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15 pages, 2949 KiB

Open AccessArticle

A Novel Medical E-Nose Signal Analysis System

by Lu Kou¹, David Zhang^1,2,* and Dongxu Liu²

¹ Biometrics Research Center, Department of Computing, The Hong Kong Polytechnic University, Kowloon 999077, Hong Kong, China

² Department of Computer Science, Harbin Institute of Technology Shenzhen graduate school, Shenzhen 518055, China

Sensors 2017, 17(4), 402; https://doi.org/10.3390/s17040402 - 5 Apr 2017

Cited by 86 | Viewed by 8152

Abstract

It has been proven that certain biomarkers in people’s breath have a relationship with diseases and blood glucose levels (BGLs). As a result, it is possible to detect diseases and predict BGLs by analysis of breath samples captured by e-noses. In this paper, [...] Read more.

It has been proven that certain biomarkers in people’s breath have a relationship with diseases and blood glucose levels (BGLs). As a result, it is possible to detect diseases and predict BGLs by analysis of breath samples captured by e-noses. In this paper, a novel optimized medical e-nose system specified for disease diagnosis and BGL prediction is proposed. A large-scale breath dataset has been collected using the proposed system. Experiments have been organized on the collected dataset and the experimental results have shown that the proposed system can well solve the problems of existing systems. The methods have effectively improved the classification accuracy. Full article

(This article belongs to the Special Issue Gas Sensors for Health Care and Medical Applications)

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18 pages, 2801 KiB

Open AccessArticle

Wideband Spectrum Sensing Based on Riemannian Distance for Cognitive Radio Networks

by Qiuyuan Lu^*, Shengzhi Yang and Fan Liu

School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China

Sensors 2017, 17(4), 661; https://doi.org/10.3390/s17040661 - 23 Mar 2017

Cited by 27 | Viewed by 5095

Abstract

Detecting the signals of the primary users in the wideband spectrum is a key issue for cognitive radio networks. In this paper, we consider the multi-antenna based signal detection in a wideband spectrum scenario where the noise statistical characteristics are assumed to be [...] Read more.

Detecting the signals of the primary users in the wideband spectrum is a key issue for cognitive radio networks. In this paper, we consider the multi-antenna based signal detection in a wideband spectrum scenario where the noise statistical characteristics are assumed to be unknown. We reason that the covariance matrices of the spectrum subbands have structural constraints and that they describe a manifold in the signal space. Thus, we propose a novel signal detection algorithm based on Riemannian distance and Riemannian mean which is different from the traditional eigenvalue-based detector (EBD) derived with the generalized likelihood ratio criterion. Using the moment matching method, we obtain the closed expression of the decision threshold. From the considered simulation settings, it is shown that the proposed Riemannian distance detector (RDD) has a better performance than the traditional EBD in wideband spectrum sensing. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 9582 KiB

Open AccessArticle

Hyperspectral Monitoring of Green Roof Vegetation Health State in Sub-Mediterranean Climate: Preliminary Results

by Patrizia Piro¹, Michele Porti², Simone Veltri¹

, Emanuela Lupo^2,3 and Monica Moroni^3,*

¹ DINCI (Dipartimento di Ingegneria Civile), University of Calabria, via P. Bucci 42B, 87036 Rende (CS), Italy

² DIMEG (Dipartimento di Ingegneria Meccanica, Energetica e Gestionale), University of Calabria, via P. Bucci 42B, 87036 Rende (CS), Italy

³ DICEA (Dipartimento di Ingegneria Civile Edile e Ambientale), Sapienza University of Rome, via Eudossiana 18, 00184 Rome, Italy

Sensors 2017, 17(4), 662; https://doi.org/10.3390/s17040662 - 23 Mar 2017

Cited by 19 | Viewed by 5774

Abstract

In urban and industrial environments, the constant increase of impermeable surfaces has produced drastic changes in the natural hydrological cycle. Decreasing green areas not only produce negative effects from a hydrological-hydraulic perspective, but also from an energy point of view, modifying the urban [...] Read more.

In urban and industrial environments, the constant increase of impermeable surfaces has produced drastic changes in the natural hydrological cycle. Decreasing green areas not only produce negative effects from a hydrological-hydraulic perspective, but also from an energy point of view, modifying the urban microclimate and generating, as shown in the literature, heat islands in our cities. In this context, green infrastructures may represent an environmental compensation action that can be used to re-equilibrate the hydrological and energy balance and reduce the impact of pollutant load on receiving water bodies. To ensure that a green infrastructure will work properly, vegetated areas have to be continuously monitored to verify their health state. This paper presents a ground spectroscopy monitoring survey of a green roof installed at the University of Calabria fulfilled via the acquisition and analysis of hyperspectral data. This study is part of a larger research project financed by European Structural funds aimed at understanding the influence of green roofs on rainwater management and energy consumption for air conditioning in the Mediterranean area. Reflectance values were acquired with a field-portable spectroradiometer that operates in the range of wavelengths 350–2500 nm. The survey was carried out during the time period November 2014–June 2015 and data were acquired weekly. Climatic, thermo-physical, hydrological and hydraulic quantities were acquired as well and related to spectral data. Broadband and narrowband spectral indices, related to chlorophyll content and to chlorophyll–carotenoid ratio, were computed. The two narrowband indices NDVI₇₀₅ and SIPI turned out to be the most representative indices to detect the plant health status. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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22 pages, 4248 KiB

Open AccessArticle

An Analytical Model for BDS B1 Spreading Code Self-Interference Evaluation Considering NH Code Effects

by Xin Zhang^1,*

, Xingqun Zhan^1,†, Shaojun Feng^2,† and Washington Ochieng^2,†

¹ School of Aeronautics and Astronautics, Shanghai Jiao Tong University, Shanghai 200240, China

² Centre for Transport Studies, Imperial College London, London SW7 2BU, UK

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 663; https://doi.org/10.3390/s17040663 - 23 Mar 2017

Cited by 2 | Viewed by 3701

Abstract

The short spreading code used by the BeiDou Navigation Satellite System (BDS) B1-I or GPS Coarse/Acquistiion (C/A) can cause aggregately undesirable cross-correlation between signals within each single constellation. This GPS-to-GPS or BDS-to-BDS correlation is referred to as self-interference. A GPS C/A code self-interference [...] Read more.

The short spreading code used by the BeiDou Navigation Satellite System (BDS) B1-I or GPS Coarse/Acquistiion (C/A) can cause aggregately undesirable cross-correlation between signals within each single constellation. This GPS-to-GPS or BDS-to-BDS correlation is referred to as self-interference. A GPS C/A code self-interference model is extended to propose a self-interference model for BDS B1, taking into account the unique feature of the B1-I signal transmitted by BDS medium Earth orbit (MEO) and inclined geosynchronous orbit (IGSO) satellites—an extra Neumann-Hoffmann (NH) code. Currently there is no analytical model for BDS self-interference and a simple three parameter analytical model is proposed. The model is developed by calculating the spectral separation coefficient (SSC), converting SSC to equivalent white noise power level, and then using this to calculate effective carrier-to-noise density ratio. Cyclostationarity embedded in the signal offers the proposed model additional accuracy in predicting B1-I self-interference. Hardware simulator data are used to validate the model. Software simulator data are used to show the impact of self-interference on a typical BDS receiver including the finding that self-interference effect is most significant when the differential Doppler between desired and undesired signal is zero. Simulation results show the aggregate noise caused by just two undesirable spreading codes on a single desirable signal could lift the receiver noise floor by 3.83 dB under extreme C/N₀ (carrier to noise density ratio) conditions (around 20 dB-Hz). This aggregate noise has the potential to increase code tracking standard deviation by 11.65 m under low C/N₀ (15–19 dB-Hz) conditions and should therefore, be avoided for high-sensitivity applications. Although the findings refer to Beidou system, the principle weakness of the short codes illuminated here are valid for other satellite navigation systems. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 7224 KiB

Open AccessArticle

Objective Video Quality Assessment Based on Machine Learning for Underwater Scientific Applications

by José-Miguel Moreno-Roldán^*

, Miguel-Ángel Luque-Nieto

, Javier Poncela

and Pablo Otero

Department of Communication Engineering, University of Málaga, 29071 Málaga, Spain

Sensors 2017, 17(4), 664; https://doi.org/10.3390/s17040664 - 23 Mar 2017

Cited by 7 | Viewed by 4711

Abstract

Video services are meant to be a fundamental tool in the development of oceanic research. The current technology for underwater networks (UWNs) imposes strong constraints in the transmission capacity since only a severely limited bitrate is available. However, previous studies have shown that [...] Read more.

Video services are meant to be a fundamental tool in the development of oceanic research. The current technology for underwater networks (UWNs) imposes strong constraints in the transmission capacity since only a severely limited bitrate is available. However, previous studies have shown that the quality of experience (QoE) is enough for ocean scientists to consider the service useful, although the perceived quality can change significantly for small ranges of variation of video parameters. In this context, objective video quality assessment (VQA) methods become essential in network planning and real time quality adaptation fields. This paper presents two specialized models for objective VQA, designed to match the special requirements of UWNs. The models are built upon machine learning techniques and trained with actual user data gathered from subjective tests. Our performance analysis shows how both of them can successfully estimate quality as a mean opinion score (MOS) value and, for the second model, even compute a distribution function for user scores. Full article

(This article belongs to the Special Issue Sensing Technologies for Autonomy and Cooperation in Underwater Networked Robot Systems)

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12 pages, 3615 KiB

Open AccessArticle

A Passive Temperature-Sensing Antenna Based on a Bimetal Strip Coil

by Xianwei Shi, Fan Yang^*, Shenheng Xu and Maokun Li

State Key Laboratory on Microwave and Digital Communications, Tsinghua National Laboratory for Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(4), 665; https://doi.org/10.3390/s17040665 - 23 Mar 2017

Cited by 10 | Viewed by 6022

Abstract

A passive temperature-sensing antenna is presented in this paper, which consists of a meandering dipole, a bimetal strip and a back cavity. The meandering dipole is divided into two parts: the lower feeding part and the upper radiating part, which maintain electric contact [...] Read more.

A passive temperature-sensing antenna is presented in this paper, which consists of a meandering dipole, a bimetal strip and a back cavity. The meandering dipole is divided into two parts: the lower feeding part and the upper radiating part, which maintain electric contact during operation. As a sensing component, a bimetal strip coil offers a twisting force to rotate the lower feeding part of the antenna when the temperature varies. As a result, the effective length of the dipole antenna changes, leading to a shift of the resonant frequency. Furthermore, a metal back cavity is added to increase the antenna’s quality factor Q, which results in a high-sensitivity design. An antenna prototype is designed, fabricated, and measured, which achieves a sensitivity larger than 4.00 MHz/°C in a temperature range from 30 °C to 50 °C and a read range longer than 4 m. Good agreement between the simulation and measurement results is obtained. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 1906 KiB

Open AccessArticle

Multi-View Structural Local Subspace Tracking

by Jie Guo¹

, Tingfa Xu^1,2,*, Guokai Shi¹, Zhitao Rao¹ and Xiangmin Li¹

¹ Image Engineering&Video Technology Lab, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China

² Key Laboratory of Photoelectronic Imaging Technology and System, Ministry of Education of China, Beijing 100081, China

Sensors 2017, 17(4), 666; https://doi.org/10.3390/s17040666 - 23 Mar 2017

Cited by 5 | Viewed by 4124

Abstract

In this paper, we propose a multi-view structural local subspace tracking algorithm based on sparse representation. We approximate the optimal state from three views: (1) the template view; (2) the PCA (principal component analysis) basis view; and (3) the target candidate view. Then [...] Read more.

In this paper, we propose a multi-view structural local subspace tracking algorithm based on sparse representation. We approximate the optimal state from three views: (1) the template view; (2) the PCA (principal component analysis) basis view; and (3) the target candidate view. Then we propose a unified objective function to integrate these three view problems together. The proposed model not only exploits the intrinsic relationship among target candidates and their local patches, but also takes advantages of both sparse representation and incremental subspace learning. The optimization problem can be well solved by the customized APG (accelerated proximal gradient) methods together with an iteration manner. Then, we propose an alignment-weighting average method to obtain the optimal state of the target. Furthermore, an occlusion detection strategy is proposed to accurately update the model. Both qualitative and quantitative evaluations demonstrate that our tracker outperforms the state-of-the-art trackers in a wide range of tracking scenarios. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 4814 KiB

Open AccessArticle

Fiber Optic Sensor Embedment Study for Multi-Parameter Strain Sensing

by Monssef Drissi-Habti^1,*, Venkadesh Raman², Aghiad Khadour³ and Safiullah Timorian¹

¹ PRES LUNAM IFSTTAR CS4 Route de Bouaye, 44344 Bouguenais, France

² Institut de Recherche Technologique (IRT) Jules VERNE, Chemin du Chaffault, 44340 Bouguenais, France

³ Components and Systems Department, Université Paris-Est, IFSTTAR, 77420 Champs-sur-Marne, France

Sensors 2017, 17(4), 667; https://doi.org/10.3390/s17040667 - 23 Mar 2017

Cited by 36 | Viewed by 6463

Abstract

The fiber optic sensors (FOSs) are commonly used for large-scale structure monitoring systems for their small size, noise free and low electrical risk characteristics. Embedded fiber optic sensors (FOSs) lead to micro-damage in composite structures. This damage generation threshold is based on the [...] Read more.

The fiber optic sensors (FOSs) are commonly used for large-scale structure monitoring systems for their small size, noise free and low electrical risk characteristics. Embedded fiber optic sensors (FOSs) lead to micro-damage in composite structures. This damage generation threshold is based on the coating material of the FOSs and their diameter. In addition, embedded FOSs are aligned parallel to reinforcement fibers to avoid micro-damage creation. This linear positioning of distributed FOS fails to provide all strain parameters. We suggest novel sinusoidal sensor positioning to overcome this issue. This method tends to provide multi-parameter strains in a large surface area. The effectiveness of sinusoidal FOS positioning over linear FOS positioning is studied under both numerical and experimental methods. This study proves the advantages of the sinusoidal positioning method for FOS in composite material’s bonding. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 456 KiB

Open AccessArticle

A Secure and Privacy-Preserving Navigation Scheme Using Spatial Crowdsourcing in Fog-Based VANETs

by Lingling Wang^*, Guozhu Liu and Lijun Sun

School of Information Science and Technology, Qingdao University of Science and Technology, Qingdao 266061, China

Sensors 2017, 17(4), 668; https://doi.org/10.3390/s17040668 - 24 Mar 2017

Cited by 54 | Viewed by 6064

Abstract

Fog-based VANETs (Vehicular ad hoc networks) is a new paradigm of vehicular ad hoc networks with the advantages of both vehicular cloud and fog computing. Real-time navigation schemes based on fog-based VANETs can promote the scheme performance efficiently. In this paper, we propose [...] Read more.

Fog-based VANETs (Vehicular ad hoc networks) is a new paradigm of vehicular ad hoc networks with the advantages of both vehicular cloud and fog computing. Real-time navigation schemes based on fog-based VANETs can promote the scheme performance efficiently. In this paper, we propose a secure and privacy-preserving navigation scheme by using vehicular spatial crowdsourcing based on fog-based VANETs. Fog nodes are used to generate and release the crowdsourcing tasks, and cooperatively find the optimal route according to the real-time traffic information collected by vehicles in their coverage areas. Meanwhile, the vehicle performing the crowdsourcing task can get a reasonable reward. The querying vehicle can retrieve the navigation results from each fog node successively when entering its coverage area, and follow the optimal route to the next fog node until it reaches the desired destination. Our scheme fulfills the security and privacy requirements of authentication, confidentiality and conditional privacy preservation. Some cryptographic primitives, including the Elgamal encryption algorithm, AES, randomized anonymous credentials and group signatures, are adopted to achieve this goal. Finally, we analyze the security and the efficiency of the proposed scheme. Full article

(This article belongs to the Special Issue Security and Privacy Challenges in Emerging Fog Computing)

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16 pages, 8820 KiB

Open AccessArticle

Radar Interferometry for Monitoring the Vibration Characteristics of Buildings and Civil Structures: Recent Case Studies in Spain

by Guido Luzi^*, Michele Crosetto and Enric Fernández

Centre Tecnòlogic de Telecomunicaciòns de Catalunya (CTTC/CERCA), Geomatics Division, Avinguda Gauss, 7, E-08860 Castelldefels (Barcelona), Spain

Sensors 2017, 17(4), 669; https://doi.org/10.3390/s17040669 - 24 Mar 2017

Cited by 53 | Viewed by 8086

Abstract

The potential of a coherent microwave sensor to monitor the vibration characteristics of civil structures has been investigated in the past decade, and successful case studies have been published by different research teams. This remote sensing technique is based on the interferometric processing [...] Read more.

The potential of a coherent microwave sensor to monitor the vibration characteristics of civil structures has been investigated in the past decade, and successful case studies have been published by different research teams. This remote sensing technique is based on the interferometric processing of real aperture radar acquisitions. Its capability to estimate, simultaneously and remotely, the displacement of different parts of the investigated structures, with high accuracy and repeatability, is its main advantage with respect to conventional sensors. A considerable amount of literature on this technique is available, including various case studies aimed at testing the ambient vibration of bridges, buildings, and towers. In the last years, this technique has been used in Spain for civil structures monitoring. In this paper, three examples of such case studies are described: the monitoring of the suspended bridge crossing the Ebro River at Amposta, the communications tower of Collserola in Barcelona, and an urban building located in Vilafranca del Penedès, a small town close to Barcelona. This paper summarizes the main outcomes of these case studies, underlining the advantages and limitations of the sensors currently available, and concluding with the possible improvements expected from the next generation of sensors. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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20 pages, 6181 KiB

Open AccessArticle

A Polynomial Subset-Based Efficient Multi-Party Key Management System for Lightweight Device Networks

by Zahid Mahmood¹, Huansheng Ning^1,*

and AtaUllah Ghafoor²

¹ School of Computer and Communication Engineering, University of Science and Technology Beijing, Beijing 100083, China

² Department of Computer Science, National University of Modern Languages, Islamabad 44000, Pakistan

Sensors 2017, 17(4), 670; https://doi.org/10.3390/s17040670 - 24 Mar 2017

Cited by 35 | Viewed by 5500

Abstract

Wireless Sensor Networks (WSNs) consist of lightweight devices to measure sensitive data that are highly vulnerable to security attacks due to their constrained resources. In a similar manner, the internet-based lightweight devices used in the Internet of Things (IoT) are facing severe security [...] Read more.

Wireless Sensor Networks (WSNs) consist of lightweight devices to measure sensitive data that are highly vulnerable to security attacks due to their constrained resources. In a similar manner, the internet-based lightweight devices used in the Internet of Things (IoT) are facing severe security and privacy issues because of the direct accessibility of devices due to their connection to the internet. Complex and resource-intensive security schemes are infeasible and reduce the network lifetime. In this regard, we have explored the polynomial distribution-based key establishment schemes and identified an issue that the resultant polynomial value is either storage intensive or infeasible when large values are multiplied. It becomes more costly when these polynomials are regenerated dynamically after each node join or leave operation and whenever key is refreshed. To reduce the computation, we have proposed an Efficient Key Management (EKM) scheme for multiparty communication-based scenarios. The proposed session key management protocol is established by applying a symmetric polynomial for group members, and the group head acts as a responsible node. The polynomial generation method uses security credentials and secure hash function. Symmetric cryptographic parameters are efficient in computation, communication, and the storage required. The security justification of the proposed scheme has been completed by using Rubin logic, which guarantees that the protocol attains mutual validation and session key agreement property strongly among the participating entities. Simulation scenarios are performed using NS 2.35 to validate the results for storage, communication, latency, energy, and polynomial calculation costs during authentication, session key generation, node migration, secure joining, and leaving phases. EKM is efficient regarding storage, computation, and communication overhead and can protect WSN-based IoT infrastructure. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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13 pages, 6633 KiB

Open AccessArticle

Real-Time Gait Event Detection Based on Kinematic Data Coupled to a Biomechanical Model †

by Stefan Lambrecht^1,2, Anna Harutyunyan³, Kevin Tanghe¹, Maarten Afschrift², Joris De Schutter¹ and Ilse Jonkers^2,*

¹ Division PMA, Department of Mechanical Engineering, Katholieke Universiteit Leuven, 3000 Leuven, Belgium

² Department of Biomedical Kinesiology, Katholieke Universiteit Leuven, 3000 Leuven, Belgium

³ AI Laboratory, Vrije Universiteit Brussel, 1050 Ixelles, Belgium

Sensors 2017, 17(4), 671; https://doi.org/10.3390/s17040671 - 24 Mar 2017

Cited by 34 | Viewed by 7991

Abstract

Real-time detection of multiple stance events, more specifically initial contact (IC), foot flat (FF), heel off (HO), and toe off (TO), could greatly benefit neurorobotic (NR) and neuroprosthetic (NP) control. Three real-time threshold-based algorithms have been developed, detecting the aforementioned events based on [...] Read more.

Real-time detection of multiple stance events, more specifically initial contact (IC), foot flat (FF), heel off (HO), and toe off (TO), could greatly benefit neurorobotic (NR) and neuroprosthetic (NP) control. Three real-time threshold-based algorithms have been developed, detecting the aforementioned events based on kinematic data in combination with a biomechanical model. Data from seven subjects walking at three speeds on an instrumented treadmill were used to validate the presented algorithms, accumulating to a total of 558 steps. The reference for the gait events was obtained using marker and force plate data. All algorithms had excellent precision and no false positives were observed. Timing delays of the presented algorithms were similar to current state-of-the-art algorithms for the detection of IC and TO, whereas smaller delays were achieved for the detection of FF. Our results indicate that, based on their high precision and low delays, these algorithms can be used for the control of an NR/NP, with the exception of the HO event. Kinematic data is used in most NR/NP control schemes and is thus available at no additional cost, resulting in a minimal computational burden. The presented methods can also be applied for screening pathological gait or gait analysis in general in/outside of the laboratory. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 1959 KiB

Open AccessArticle

Using an Active-Optical Sensor to Develop an Optimal NDVI Dynamic Model for High-Yield Rice Production (Yangtze, China)

by Xiaojun Liu¹, Richard B. Ferguson², Hengbiao Zheng¹, Qiang Cao¹, Yongchao Tian¹, Weixing Cao¹ and Yan Zhu^1,*

¹ National Engineering and Technology Center for Information Agriculture, Key Laboratory for Crop System Analysis and Decision Making, Ministry of Agriculture, Jiangsu Key Laboratory for Information Agriculture, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing 210095, China

² Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68583, USA

Sensors 2017, 17(4), 672; https://doi.org/10.3390/s17040672 - 24 Mar 2017

Cited by 39 | Viewed by 5803

Abstract

The successful development of an optimal canopy vegetation index dynamic model for obtaining higher yield can offer a technical approach for real-time and nondestructive diagnosis of rice (Oryza sativa L) growth and nitrogen (N) nutrition status. In this study, multiple rice cultivars and [...] Read more.

The successful development of an optimal canopy vegetation index dynamic model for obtaining higher yield can offer a technical approach for real-time and nondestructive diagnosis of rice (Oryza sativa L) growth and nitrogen (N) nutrition status. In this study, multiple rice cultivars and N treatments of experimental plots were carried out to obtain: normalized difference vegetation index (NDVI), leaf area index (LAI), above-ground dry matter (DM), and grain yield (GY) data. The quantitative relationships between NDVI and these growth indices (e.g., LAI, DM and GY) were analyzed, showing positive correlations. Using the normalized modeling method, an appropriate NDVI simulation model of rice was established based on the normalized NDVI (RNDVI) and relative accumulative growing degree days (RAGDD). The NDVI dynamic model for high-yield production in rice can be expressed by a double logistic model:

RNDVI = {(1 + e^{- 15.2829 \times (R A G D D_{i} - 0.1944)})}^{- 1} - {(1 + e^{- 11.6517 \times (R A G D D_{i} - 1.0267)})}^{- 1}

(R2 = 0.8577**), which can be used to accurately predict canopy NDVI dynamic changes during the entire growth period. Considering variation among rice cultivars, we constructed two relative NDVI (RNDVI) dynamic models for Japonica and Indica rice types, with R2 reaching 0.8764** and 0.8874**, respectively. Furthermore, independent experimental data were used to validate the RNDVI dynamic models. The results showed that during the entire growth period, the accuracy (k), precision (R2), and standard deviation of RNDVI dynamic models for the Japonica and Indica cultivars were 0.9991, 1.0170; 0.9084**, 0.8030**; and 0.0232, 0.0170, respectively. These results indicated that RNDVI dynamic models could accurately reflect crop growth and predict dynamic changes in high-yield crop populations, providing a rapid approach for monitoring rice growth status. Full article

(This article belongs to the Section State-of-the-Art Sensors Technologies)

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16 pages, 18300 KiB

Open AccessArticle

How to Make Reliable, Washable, and Wearable Textronic Devices

by Xuyuan Tao^1,*, Vladan Koncar¹, Tzu-Hao Huang²

, Chien-Lung Shen², Ya-Chi Ko² and Gwo-Tsuen Jou²

¹ Ecole Nationale Supérieure des Arts et Industries Textiles, 2 allée Louise et Victor Champier, 59056 Roubaix CEDEX 1, France

² Taiwan Textile Research Institute, No. 6, Chengtian Rd., Tucheng Dist., New Taipei City 23674, Taiwan

Sensors 2017, 17(4), 673; https://doi.org/10.3390/s17040673 - 24 Mar 2017

Cited by 99 | Viewed by 8307

Abstract

In this paper, the washability of wearable textronic (textile-electronic) devices has been studied. Two different approaches aiming at designing, producing, and testing robust washable and reliable smart textile systems are presented. The common point of the two approaches is the use of flexible [...] Read more.

In this paper, the washability of wearable textronic (textile-electronic) devices has been studied. Two different approaches aiming at designing, producing, and testing robust washable and reliable smart textile systems are presented. The common point of the two approaches is the use of flexible conductive PCB in order to interface the miniaturized rigid (traditional) electronic devices to conductive threads and tracks within the textile flexible fabric and to connect them to antenna, textile electrodes, sensors, actuators, etc. The first approach consists in the use of TPU films (thermoplastic polyurethane) that are deposited by the press under controlled temperature and pressure parameters in order to protect the conductive thread and electrical contacts. The washability of conductive threads and contact resistances between flexible PCB and conductive threads are tested. The second approach is focused on the protection of the whole system—composed of a rigid electronic device, flexible PCB, and textile substrate—by a barrier made of latex. Three types of prototypes were realized and washed. Their reliabilities are studied. Full article

(This article belongs to the Special Issue Flexible Electronics and Sensors)

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19 pages, 1942 KiB

Open AccessArticle

Node Self-Deployment Algorithm Based on Pigeon Swarm Optimization for Underwater Wireless Sensor Networks

by Shanen Yu, Yiming Xu, Peng Jiang^*, Feng Wu and Huan Xu

College of Automation, Hangzhou Dianzi University, Hangzhou 310018, China

Sensors 2017, 17(4), 674; https://doi.org/10.3390/s17040674 - 24 Mar 2017

Cited by 10 | Viewed by 4912

Abstract

At present, free-to-move node self-deployment algorithms aim at event coverage and cannot improve network coverage under the premise of considering network connectivity, network reliability and network deployment energy consumption. Thus, this study proposes pigeon-based self-deployment algorithm (PSA) for underwater wireless sensor networks to [...] Read more.

At present, free-to-move node self-deployment algorithms aim at event coverage and cannot improve network coverage under the premise of considering network connectivity, network reliability and network deployment energy consumption. Thus, this study proposes pigeon-based self-deployment algorithm (PSA) for underwater wireless sensor networks to overcome the limitations of these existing algorithms. In PSA, the sink node first finds its one-hop nodes and maximizes the network coverage in its one-hop region. The one-hop nodes subsequently divide the network into layers and cluster in each layer. Each cluster head node constructs a connected path to the sink node to guarantee network connectivity. Finally, the cluster head node regards the ratio of the movement distance of the node to the change in the coverage redundancy ratio as the target function and employs pigeon swarm optimization to determine the positions of the nodes. Simulation results show that PSA improves both network connectivity and network reliability, decreases network deployment energy consumption, and increases network coverage. Full article

(This article belongs to the Special Issue Advances and Challenges in Underwater Sensor Networks)

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15 pages, 9320 KiB

Open AccessArticle

A Formaldehyde Sensor Based on Molecularly-Imprinted Polymer on a TiO₂ Nanotube Array

by Xiaohui Tang^1,*, Jean-Pierre Raskin¹, Driss Lahem², Arnaud Krumpmann³, André Decroly³ and Marc Debliquy³

¹ ICTEAM, Université catholique de Louvain (UCL), Place du Levant, 3, 1348 Louvain-la-Neuve, Belgium

² Department of Materials Science, Materia Nova ASBL, 7000 Mons, Belgium

³ Materials Science Department, University of Mons, 7000 Mons, Belgium

Sensors 2017, 17(4), 675; https://doi.org/10.3390/s17040675 - 24 Mar 2017

Cited by 65 | Viewed by 8950

Abstract

Today, significant attention has been brought to the development of sensitive, specific, cheap, and reliable sensors for real-time monitoring. Molecular imprinting technology is a versatile and promising technology for practical applications in many areas, particularly chemical sensors. Here, we present a chemical sensor [...] Read more.

Today, significant attention has been brought to the development of sensitive, specific, cheap, and reliable sensors for real-time monitoring. Molecular imprinting technology is a versatile and promising technology for practical applications in many areas, particularly chemical sensors. Here, we present a chemical sensor for detecting formaldehyde, a toxic common indoor pollutant gas. Polypyrrole-based molecularly-imprinted polymer (PPy-based MIP) is employed as the sensing recognition layer and synthesized on a titanium dioxide nanotube array (TiO₂-NTA) for increasing its surface-to-volume ratio, thereby improving the sensor performance. Our sensor selectively detects formaldehyde in the parts per million (ppm) range at room temperature. It also shows a long-term stability and small fluctuation to humidity variations. These are attributed to the thin fishnet-like structure of the PPy-based MIP on the highly-ordered and vertically-aligned TiO₂-NTA. Full article

(This article belongs to the Special Issue Molecular Imprinting and Functional Polymers for all Transducers and Applications)

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12 pages, 5670 KiB

Open AccessArticle

Construction of an Acetylcholinesterase Sensor Based on Synthesized Paramagnetic Nanoparticles, a Simple Tool for Neurotoxic Compounds Assay

by Adam Kostelnik^1,2, Pavel Kopel^3,4

, Alexander Cegan¹ and Miroslav Pohanka^2,5,*

¹ Faculty of Chemical Technology, University of Pardubice, Studentska 95, Pardubice CZ-53210, Czech Republic

² Faculty of Military Health Sciences, University of Defense, Trebesska 1575, Hradec Kralove CZ-50001, Czech Republic

³ Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, Brno CZ-61300, Czech Republic

⁴ Central European Institute of Technology, Brno University of Technology, Purkynova 123, Brno CZ-61200, Czech Republic

⁵ Department of Geology and Pedology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Brno CZ-61300, Czech Republic

Sensors 2017, 17(4), 676; https://doi.org/10.3390/s17040676 - 24 Mar 2017

Cited by 14 | Viewed by 4996

Abstract

Magnetic particles (MPs) have been widely used in biological applications in recent years as a carrier for various molecules. Their big advantage is in repeated use of immobilized molecules including enzymes. Acetylcholinesterase (AChE) is an enzyme playing crucial role in neurotransmission and the [...] Read more.

Magnetic particles (MPs) have been widely used in biological applications in recent years as a carrier for various molecules. Their big advantage is in repeated use of immobilized molecules including enzymes. Acetylcholinesterase (AChE) is an enzyme playing crucial role in neurotransmission and the enzyme is targeted by various molecules like Alzheimer’s drugs, pesticides and warfare agents. In this work, an electrochemical biosensor having AChE immobilized onto MPs and stabilized through glutaraldehyde (GA) molecule was proposed for assay of the neurotoxic compounds. The prepared nanoparticles were modified by pure AChE and they were used for the measurement anti-Alzheimer’s drug galantamine and carbamate pesticide carbofuran with limit of detection 1.5 µM and 20 nM, respectively. All measurements were carried out using screen-printed sensor with carbon working, silver reference, and carbon auxiliary electrode. Standard Ellman’s assay was used for validation measurement of both inhibitors. Part of this work was the elimination of reversible inhibitors represented by galantamine from the active site of AChE. For this purpose, we used a lower pH to get the original activity of AChE after inhibition by galantamine. We also observed decarbamylation of the AChE-carbofuran adduct. Influence of organic solvents to AChE as well as repeatability of measurement with MPs with AChE was also established. Full article

(This article belongs to the Section Biosensors)

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17 pages, 5847 KiB

Open AccessArticle

A Smart Sensor for Defending against Clock Glitching Attacks on the I2C Protocol in Robotic Applications

by Raúl Jiménez-Naharro, Fernando Gómez-Bravo^*, Jonathan Medina-García, Manuel Sánchez-Raya and Juan Antonio Gómez-Galán

Department of Electronic Engineering, Computers, and Automation, University of Huelva, Ctra Huelva-La Rábida, s/n, 21819 Huelva, Spain

Sensors 2017, 17(4), 677; https://doi.org/10.3390/s17040677 - 25 Mar 2017

Cited by 11 | Viewed by 8201

Abstract

This paper presents a study about hardware attacking and clock signal vulnerability. It considers a particular type of attack on the clock signal in the I2C protocol, and proposes the design of a new sensor for detecting and defending against this type of [...] Read more.

This paper presents a study about hardware attacking and clock signal vulnerability. It considers a particular type of attack on the clock signal in the I2C protocol, and proposes the design of a new sensor for detecting and defending against this type of perturbation. The analysis of the attack and the defense is validated by means of a configurable experimental platform that emulates a differential drive robot. A set of experimental results confirm the interest of the studied vulnerabilities and the efficiency of the proposed sensor in defending against this type of situation. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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14 pages, 2343 KiB

Open AccessArticle

SmartFluo: A Method and Affordable Adapter to Measure Chlorophyll a Fluorescence with Smartphones

by Anna Friedrichs^1,*, Julia Anke Busch^1,2, Hendrik Jan Van der Woerd³

and Oliver Zielinski¹

¹ Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University Oldenburg, Schleusenstrasse 1, 26382 Wilhelmshaven, Germany

² Life Sciences and Chemistry, Jacobs University, Campus Ring 1, 28759 Bremen, Germany

³ Institute for Environmental Studies, VU University Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands

Sensors 2017, 17(4), 678; https://doi.org/10.3390/s17040678 - 25 Mar 2017

Cited by 49 | Viewed by 7794

Abstract

In order to increase the monitoring capabilities of inland and coastal waters, there is a need for new, affordable, sensitive and mobile instruments that could be operated semi-automatically in the field. This paper presents a prototype device to measure chlorophyll a fluorescence: the [...] Read more.

In order to increase the monitoring capabilities of inland and coastal waters, there is a need for new, affordable, sensitive and mobile instruments that could be operated semi-automatically in the field. This paper presents a prototype device to measure chlorophyll a fluorescence: the SmartFluo. The device is a combination of a smartphone offering an intuitive operation interface and an adapter implying a cuvette holder, as well as a suitable illumination source. SmartFluo is based on stimulated fluorescence of water constituents such as chlorophyll a. The red band of the digital smartphone camera is sensitive enough to detect quantitatively the characteristic red fluorescence emission. The adapter contains a light source, a strong light emitting diode and additional filters to enhance the signal-to-noise ratio and to suppress the impact of scattering. A novel algorithm utilizing the red band of the camera is provided. Laboratory experiments of the SmartFluo show a linear correlation (R

^{2}

= 0.98) to the chlorophyll a concentrations measured by reference instruments, such as a high-performance benchtop laboratory fluorometer (LS 55, PerkinElmer). Full article

(This article belongs to the Section Chemical Sensors)

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17 pages, 1067 KiB

Open AccessArticle

A Power Planning Algorithm Based on RPL for AMI Wireless Sensor Networks

by Marcio L. F. Miguel, Edgard Jamhour, Marcelo E. Pellenz

and Manoel C. Penna^*

PPGIa, Pontifical Catholic University of Parana—Parana, Curitiba 80215-901, Brazil

Sensors 2017, 17(4), 679; https://doi.org/10.3390/s17040679 - 25 Mar 2017

Cited by 14 | Viewed by 3907

Abstract

The advanced metering infrastructure (AMI) is an architecture for two-way communication between electric, gas and water meters and city utilities. The AMI network is a wireless sensor network that provides communication for metering devices in the neighborhood area of the smart grid. Recently, [...] Read more.

The advanced metering infrastructure (AMI) is an architecture for two-way communication between electric, gas and water meters and city utilities. The AMI network is a wireless sensor network that provides communication for metering devices in the neighborhood area of the smart grid. Recently, the applicability of a routing protocol for low-power and lossy networks (RPL) has been considered in AMI networks. Some studies in the literature have pointed out problems with RPL, including sub-optimal path selection and instability. In this paper, we defend the viewpoint that careful planning of the transmission power in wireless RPL networks can significantly reduce the pointed problems. This paper presents a method for planning the transmission power in order to assure that, after convergence, the size of the parent set of the RPL nodes is as close as possible to a predefined size. Another important feature is that all nodes in the parent set offer connectivity through links of similar quality. Full article

(This article belongs to the Section Sensor Networks)

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19 pages, 6901 KiB

Open AccessArticle

An Effective Terrain Aided Navigation for Low-Cost Autonomous Underwater Vehicles

by Ling Zhou^1,2,3, Xianghong Cheng^1,3,*

, Yixian Zhu^1,3, Chenxi Dai^1,3 and Jinbo Fu¹

¹ School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

² Department of Physics and Electronic Engineering, Yuncheng University, Yuncheng 044000, China

³ Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology, Ministry of Education, Southeast University, Nanjing 210096, China

Sensors 2017, 17(4), 680; https://doi.org/10.3390/s17040680 - 25 Mar 2017

Cited by 24 | Viewed by 6657

Abstract

Terrain-aided navigation is a potentially powerful solution for obtaining submerged position fixes for autonomous underwater vehicles. The application of terrain-aided navigation with high-accuracy inertial navigation systems has demonstrated meter-level navigation accuracy in sea trials. However, available sensors may be limited depending on the [...] Read more.

Terrain-aided navigation is a potentially powerful solution for obtaining submerged position fixes for autonomous underwater vehicles. The application of terrain-aided navigation with high-accuracy inertial navigation systems has demonstrated meter-level navigation accuracy in sea trials. However, available sensors may be limited depending on the type of the mission. Such limitations, especially for low-grade navigation sensors, not only degrade the accuracy of traditional navigation systems, but further impact the ability to successfully employ terrain-aided navigation. To address this problem, a tightly-coupled navigation is presented to successfully estimate the critical sensor errors by incorporating raw sensor data directly into an augmented navigation system. Furthermore, three-dimensional distance errors are calculated, providing measurement updates through the particle filter for absolute and bounded position error. The development of the terrain aided navigation system is elaborated for a vehicle equipped with a non-inertial-grade strapdown inertial navigation system, a 4-beam Doppler Velocity Log range sensor and a sonar altimeter. Using experimental data for navigation performance evaluation in areas with different terrain characteristics, the experiment results further show that the proposed method can be successfully applied to the low-cost AUVs and significantly improves navigation performance. Full article

(This article belongs to the Special Issue Sensing Technologies for Autonomy and Cooperation in Underwater Networked Robot Systems)

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8 pages, 2534 KiB

Open AccessArticle

Fast and Selective Plasmonic Serotonin Detection with Aptamer-Gold Nanoparticle Conjugates

by Jorge L. Chávez, Joshua A. Hagen and Nancy Kelley-Loughnane^*

711th Human Performance Wing, Airman Systems Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH 45433, USA

Sensors 2017, 17(4), 681; https://doi.org/10.3390/s17040681 - 25 Mar 2017

Cited by 57 | Viewed by 9238

Abstract

Neurotransmitters detection is critical to understanding communication between the brain and peripheral tissue. Serotonin is a key neurotransmitter linked to a number of conditions, but a full understanding of its role in disease is still lacking. The development of fast and selective serotonin [...] Read more.

Neurotransmitters detection is critical to understanding communication between the brain and peripheral tissue. Serotonin is a key neurotransmitter linked to a number of conditions, but a full understanding of its role in disease is still lacking. The development of fast and selective serotonin detection platforms will provide researchers with tools to monitor serotonin in individuals before and after treatment for the condition of interest. Aptamer-gold nanoparticles conjugates that responded colorimetrically to serotonin with minimal response to its metabolite and other neurotransmitters were designed by simply adsorbing the DNA on the surface of AuNPs. A plasmonic assay for serotonin detection was designed with a response to biologically relevant serotonin levels. Importantly, the assay performance was not compromised when tested in filtered spiked fetal bovine serum as a mimic of biofluids. This work shows that these simple and stable Apt-AuNP conjugates are promising tools to develop fast assays for point-of-care and personalized diagnostics applications. Full article

(This article belongs to the Section Biosensors)

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19 pages, 534 KiB

Open AccessArticle

DOA Estimation of Coherent Signals on Coprime Arrays Exploiting Fourth-Order Cumulants

by Yang Hu, Yimin Liu^* and Xiqin Wang

Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(4), 682; https://doi.org/10.3390/s17040682 - 25 Mar 2017

Cited by 19 | Viewed by 5471

Abstract

This paper considers the problem of direction-of-arrival (DOA) estimation of coherent signals on passive coprime arrays, where we resort to the fourth-order cumulants of the received signal to explore more information. A fourth-order cumulant matrix (FCM) is introduced for the coprime array. The [...] Read more.

This paper considers the problem of direction-of-arrival (DOA) estimation of coherent signals on passive coprime arrays, where we resort to the fourth-order cumulants of the received signal to explore more information. A fourth-order cumulant matrix (FCM) is introduced for the coprime array. The special structure of the FCM is combined with the array configuration to resolve the coherent signals. Since each sparse array of a coprime array is uniform, a series of overlapping identical subarrays can be extracted. Using this property, we propose a generalized spatial smoothing scheme applied to the FCM. From the smoothed FCM, the DOAs of both the coherent and independent signals can be successfully estimated on the pseudo-spectrum generated by the fourth-order MUSIC algorithm. To overcome the problem of occasional false peaks appearing on the pseudo-spectrum, we use a supplementary sparse array whose inter-sensor spacing is coprime to that of either existing sparse array. From the combined spectrum aided by the supplementary sensors, the false peaks are removed while the true peaks remain. The effectiveness of the proposed methods is demonstrated by simulation examples. Full article

(This article belongs to the Special Issue Recent Advances in Array Signal Processing and Its Applications in IoT Security)

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13 pages, 3584 KiB

Open AccessArticle

Rapid and Low-Cost CRP Measurement by Integrating a Paper-Based Microfluidic Immunoassay with Smartphone (CRP-Chip)

by Meili Dong^1,2, Jiandong Wu², Zimin Ma², Hagit Peretz-Soroka², Michael Zhang³, Paul Komenda³, Navdeep Tangri³, Yong Liu^1,*, Claudio Rigatto^3,* and Francis Lin^2,4,5,6,*

¹ Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China

² Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

³ Seven Oaks General Hospital, Winnipeg, MB R2V 3M3, Canada

⁴ Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

⁵ Department of Immunology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

⁶ Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada

Sensors 2017, 17(4), 684; https://doi.org/10.3390/s17040684 - 26 Mar 2017

Cited by 49 | Viewed by 10999

Abstract

Traditional diagnostic tests for chronic diseases are expensive and require a specialized laboratory, therefore limiting their use for point-of-care (PoC) testing. To address this gap, we developed a method for rapid and low-cost C-reactive protein (CRP) detection from blood by integrating a paper-based [...] Read more.

Traditional diagnostic tests for chronic diseases are expensive and require a specialized laboratory, therefore limiting their use for point-of-care (PoC) testing. To address this gap, we developed a method for rapid and low-cost C-reactive protein (CRP) detection from blood by integrating a paper-based microfluidic immunoassay with a smartphone (CRP-Chip). We chose CRP for this initial development because it is a strong biomarker of prognosis in chronic heart and kidney disease. The microfluidic immunoassay is realized by lateral flow and gold nanoparticle-based colorimetric detection of the target protein. The test image signal is acquired and analyzed using a commercial smartphone with an attached microlens and a 3D-printed chip–phone interface. The CRP-Chip was validated for detecting CRP in blood samples from chronic kidney disease patients and healthy subjects. The linear detection range of the CRP-Chip is up to 2 μg/mL and the detection limit is 54 ng/mL. The CRP-Chip test result yields high reproducibility and is consistent with the standard ELISA kit. A single CRP-Chip can perform the test in triplicate on a single chip within 15 min for less than 50 US cents of material cost. This CRP-Chip with attractive features of low-cost, fast test speed, and integrated easy operation with smartphones has the potential to enable future clinical PoC chronic disease diagnosis and risk stratification by parallel measurements of a panel of protein biomarkers. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Canada 2017)

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13 pages, 1519 KiB

Open AccessArticle

Automatic Camera Calibration Using Active Displays of a Virtual Pattern

by Lei Tan^1,*, Yaonan Wang^1,2, Hongshan Yu^2,* and Jiang Zhu³

¹ College of Electrical and Information Engineering, Hunan University, Changsha 410082, China

² National Engineering Laboratory for Robot Visual Perception and Control Technology, Hunan University, Changsha 410082, China

³ College of Information Engineering, Xiangtan University, Yuhu District, Xiangtan 411105, China

Sensors 2017, 17(4), 685; https://doi.org/10.3390/s17040685 - 27 Mar 2017

Cited by 29 | Viewed by 8503

Abstract

Camera calibration plays a critical role in 3D computer vision tasks. The most commonly used calibration method utilizes a planar checkerboard and can be done nearly fully automatically. However, it requires the user to move either the camera or the checkerboard during the [...] Read more.

Camera calibration plays a critical role in 3D computer vision tasks. The most commonly used calibration method utilizes a planar checkerboard and can be done nearly fully automatically. However, it requires the user to move either the camera or the checkerboard during the capture step. This manual operation is time consuming and makes the calibration results unstable. In order to solve the above problems caused by manual operation, this paper presents a full-automatic camera calibration method using a virtual pattern instead of a physical one. The virtual pattern is actively transformed and displayed on a screen so that the control points of the pattern can be uniformly observed in the camera view. The proposed method estimates the camera parameters from point correspondences between 2D image points and the virtual pattern. The camera and the screen are fixed during the whole process; therefore, the proposed method does not require any manual operations. Performance of the proposed method is evaluated through experiments on both synthetic and real data. Experimental results show that the proposed method can achieve stable results and its accuracy is comparable to the standard method by Zhang. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 7747 KiB

Open AccessArticle

A Correlation-Based Joint CFAR Detector Using Adaptively-Truncated Statistics in SAR Imagery

by Jiaqiu Ai^1,*, Xuezhi Yang¹, Fang Zhou¹

, Zhangyu Dong¹, Lu Jia¹ and He Yan²

¹ School of Computer and Information, Hefei University of Technology, Tunxi Road, Hefei 230009, China

² College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Avenue, Nanjing 210016, China

Sensors 2017, 17(4), 686; https://doi.org/10.3390/s17040686 - 27 Mar 2017

Cited by 17 | Viewed by 5459

Abstract

Traditional constant false alarm rate (CFAR) detectors only use the contrast information between ship targets and clutter, and they suffer probability of detection (PD) degradation in multiple target situations. This paper proposes a correlation-based joint CFAR detector using adaptively-truncated statistics (hereafter called TS-2DLNCFAR) [...] Read more.

Traditional constant false alarm rate (CFAR) detectors only use the contrast information between ship targets and clutter, and they suffer probability of detection (PD) degradation in multiple target situations. This paper proposes a correlation-based joint CFAR detector using adaptively-truncated statistics (hereafter called TS-2DLNCFAR) in SAR images. The proposed joint CFAR detector exploits the gray intensity correlation characteristics by building a two-dimensional (2D) joint log-normal model as the joint distribution (JPDF) of the clutter, so joint CFAR detection is realized. Inspired by the CFAR detection methodology, we design an adaptive threshold-based clutter truncation method to eliminate the high-intensity outliers, such as interfering ship targets, side-lobes, and ghosts in the background window, whereas the real clutter samples are preserved to the largest degree. A 2D joint log-normal model is accurately built using the adaptively-truncated clutter through simple parameter estimation, so the joint CFAR detection performance is greatly improved. Compared with traditional CFAR detectors, the proposed TS-2DLNCFAR detector achieves a high PD and a low false alarm rate (FAR) in multiple target situations. The superiority of the proposed TS-2DLNCFAR detector is validated on the multi-look Envisat-ASAR and TerraSAR-X data. Full article

(This article belongs to the Section Remote Sensors)

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10 pages, 3753 KiB

Open AccessArticle

Minimized Bolus-Type Wireless Sensor Node with a Built-In Three-Axis Acceleration Meter for Monitoring a Cow’s Rumen Conditions

by Hirofumi Nogami^1,2,*, Shozo Arai³, Hironao Okada², Lan Zhan² and Toshihiro Itoh^2,4

¹ Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan

² Research Center for Ubiquitous MEMS and Micro Engineering (UMEMSME), Advanced Industrial Science and Technology (AIST), Tukuba 305-8564, Japan

³ National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tukuba 305-0856, Japan

⁴ Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8563, Japan

Sensors 2017, 17(4), 687; https://doi.org/10.3390/s17040687 - 27 Mar 2017

Cited by 30 | Viewed by 8243

Abstract

Monitoring rumen conditions in cows is important because a dysfunctional rumen system may cause death. Sub-acute ruminal acidosis (SARA) is a typical disease in cows, and is characterized by repeated periods of low ruminal pH. SARA is regarded as a trigger for rumen [...] Read more.

Monitoring rumen conditions in cows is important because a dysfunctional rumen system may cause death. Sub-acute ruminal acidosis (SARA) is a typical disease in cows, and is characterized by repeated periods of low ruminal pH. SARA is regarded as a trigger for rumen atony, rumenitis, and abomasal displacement, which may cause death. In previous studies, rumen conditions were evaluated by wireless sensor nodes with pH measurement capability. The primary advantage of the pH sensor is its ability to continuously measure ruminal pH. However, these sensor nodes have short lifetimes since they are limited by the finite volume of the internal liquid of the reference electrode. Mimicking rumen atony, we attempt to evaluate the rumen condition using wireless sensor nodes with three-axis accelerometers. The theoretical life span of such sensor nodes depends mainly on the transmission frequency of acceleration data and the size of the battery, and the proposed sensor nodes are 30.0 mm in diameter and 70.0 mm in length and have a life span of over 600 days. Using the sensor nodes, we compare the rumen motility of the force transducer measurement with the three-axis accelerometer data. As a result, we can detect discriminative movement of rumen atony. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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9 pages, 568 KiB

Open AccessArticle

Recognition of the Duration and Prediction of Insect Prevalence of Stored Rough Rice Infested by the Red Flour Beetle (Tribolium castaneum Herbst) Using an Electronic Nose

by Sai Xu¹, Zhiyan Zhou^1,2,*

, Keliang Li¹, Sierra Mari Jamir³ and Xiwen Luo¹

¹ South China Agricultural University/Engineering Research Center for Agricultural Aviation Application (ERCAAA), Guangzhou 510642, China

² Collaborative Innovation Center for Grain and Oil Crops in South China, Changsha 410128, China

³ Department of Food Science, Cornell University, Stocking Hall, Ithaca, NY 14853, USA

Sensors 2017, 17(4), 688; https://doi.org/10.3390/s17040688 - 14 Apr 2017

Cited by 21 | Viewed by 5831

Abstract

The purpose of this research is to explore the feasibility of applying an electronic nose for the intelligent monitoring of injurious insects in a stored grain environment. In this study, we employed an electronic nose to sample rough rice that contained three degrees [...] Read more.

The purpose of this research is to explore the feasibility of applying an electronic nose for the intelligent monitoring of injurious insects in a stored grain environment. In this study, we employed an electronic nose to sample rough rice that contained three degrees of red flour beetle (Tribolium castaneum Herbst) infestation for different durations—light degree (LD), middle degree (MD), and heavy degree (HD)—and manually investigated the insect situation at the same time. Manual insect situation investigation shows that, in all three rice treatments, the insect amounts gradually decreased after infestation. When the insect population of stored rough rice was under 13 insects per 60 g of rough rice, the natural speed of decrease of the insect population became very slow and reached the best artificial insect killing period. Linear discriminant analysis (LDA) provided good performance for MD and HD insect harm duration identification, but performed poorly for LD insect harm duration identification. Both k-means clustering analysis (K-means) and fuzzy c-means analysis (FCM) effectively identified the insect harm duration for stored rough rice. The results from the back-propagation artificial neural network (BPNN) insect prevalence prediction for the three degrees of rough rice infestation demonstrated that the electronic nose could effectively predict insect prevalence in stored grain (fitting coefficients were larger than 0.89). The predictive ability was best for LD, second best for MD, and least accurate for HD. This experiment demonstrates the feasibility of electronic noses for detecting both the duration and prevalence of an insect infestation in stored grain and provides a reference for the intelligent monitoring of an insect infestation in stored grains. Full article

(This article belongs to the Section Chemical Sensors)

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18 pages, 5520 KiB

Open AccessArticle

Intelligent Diagnosis Method for Rotating Machinery Using Dictionary Learning and Singular Value Decomposition

by Te Han¹

, Dongxiang Jiang^1,*, Xiaochen Zhang¹ and Yankui Sun²

¹ State Key Lab of Control and Simulation of Power Systems and Generation Equipment, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China

² Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(4), 689; https://doi.org/10.3390/s17040689 - 27 Mar 2017

Cited by 32 | Viewed by 6844

Abstract

Rotating machinery is widely used in industrial applications. With the trend towards more precise and more critical operating conditions, mechanical failures may easily occur. Condition monitoring and fault diagnosis (CMFD) technology is an effective tool to enhance the reliability and security of rotating [...] Read more.

Rotating machinery is widely used in industrial applications. With the trend towards more precise and more critical operating conditions, mechanical failures may easily occur. Condition monitoring and fault diagnosis (CMFD) technology is an effective tool to enhance the reliability and security of rotating machinery. In this paper, an intelligent fault diagnosis method based on dictionary learning and singular value decomposition (SVD) is proposed. First, the dictionary learning scheme is capable of generating an adaptive dictionary whose atoms reveal the underlying structure of raw signals. Essentially, dictionary learning is employed as an adaptive feature extraction method regardless of any prior knowledge. Second, the singular value sequence of learned dictionary matrix is served to extract feature vector. Generally, since the vector is of high dimensionality, a simple and practical principal component analysis (PCA) is applied to reduce dimensionality. Finally, the K-nearest neighbor (KNN) algorithm is adopted for identification and classification of fault patterns automatically. Two experimental case studies are investigated to corroborate the effectiveness of the proposed method in intelligent diagnosis of rotating machinery faults. The comparison analysis validates that the dictionary learning-based matrix construction approach outperforms the mode decomposition-based methods in terms of capacity and adaptability for feature extraction. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 523 KiB

Open AccessArticle

Impact of Beamforming on the Path Connectivity in Cognitive Radio Ad Hoc Networks

by Le The Dung¹

, Tran Dinh Hieu²

, Seong-Gon Choi^1,*, Byung-Seo Kim³

and Beongku An³

¹ Department of Radio and Communication Engineering, Chungbuk National University, Cheongju City, Chungbuk 28644, Korea

² Department of Electronics and Computer Engineering in Graduate School, Hongik University, Sejong City 30016, Korea

³ Department of Computer and Information Communication Engineering, Hongik University, Sejong City 30016, Korea

Sensors 2017, 17(4), 690; https://doi.org/10.3390/s17040690 - 27 Mar 2017

Cited by 9 | Viewed by 4450

Abstract

This paper investigates the impact of using directional antennas and beamforming schemes on the connectivity of cognitive radio ad hoc networks (CRAHNs). Specifically, considering that secondary users use two kinds of directional antennas, i.e., uniform linear array (ULA) and uniform circular array (UCA) [...] Read more.

This paper investigates the impact of using directional antennas and beamforming schemes on the connectivity of cognitive radio ad hoc networks (CRAHNs). Specifically, considering that secondary users use two kinds of directional antennas, i.e., uniform linear array (ULA) and uniform circular array (UCA) antennas, and two different beamforming schemes, i.e., randomized beamforming and center-directed to communicate with each other, we study the connectivity of all combination pairs of directional antennas and beamforming schemes and compare their performances to those of omnidirectional antennas. The results obtained in this paper show that, compared with omnidirectional transmission, beamforming transmission only benefits the connectivity when the density of secondary user is moderate. Moreover, the combination of UCA and randomized beamforming scheme gives the highest path connectivity in all evaluating scenarios. Finally, the number of antenna elements and degree of path loss greatly affect path connectivity in CRAHNs. Full article

(This article belongs to the Special Issue Selected Papers from 2016 International Symposium on Computer, Consumer and Control (IS3C 2016))

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15 pages, 2062 KiB

Open AccessArticle

Investigation on Inter-Limb Coordination and Motion Stability, Intensity and Complexity of Trunk and Limbs during Hands-Knees Crawling in Human Adults

by Shenglan Ma, Xiang Chen^*, Shuai Cao

, Yi Yu and Xu Zhang

Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230026, China

Sensors 2017, 17(4), 692; https://doi.org/10.3390/s17040692 - 28 Mar 2017

Cited by 13 | Viewed by 5987

Abstract

This study aimed to investigate the inter-limb coordination pattern and the stability, intensity, and complexity of the trunk and limbs motions in human crawling under different speeds. Thirty healthy human adults finished hands-knees crawling trials on a treadmill at six different speeds (from [...] Read more.

This study aimed to investigate the inter-limb coordination pattern and the stability, intensity, and complexity of the trunk and limbs motions in human crawling under different speeds. Thirty healthy human adults finished hands-knees crawling trials on a treadmill at six different speeds (from 1 km/h to 2.5 km/h). A home-made multi-channel acquisition system consisting of five 3-axis accelerometers (ACC) and four force sensors was used for the data collection. Ipsilateral phase lag was used to represent inter-limb coordination pattern during crawling and power, harmonic ratio, and sample entropy of acceleration signals were adopted to depict the motion intensity, stability, and complexity of trunk and limbs respectively. Our results revealed some relationships between inter-limb coordination patterns and the stability and complexity of trunk movement. Trot-like crawling pattern was found to be the most stable and regular one at low speed in the view of trunk movement, and no-limb-pairing pattern showed the lowest stability and the greatest complexity at high speed. These relationships could be used to explain why subjects tended to avoid no-limb-pairing pattern when speed was over 2 km/h no matter which coordination type they used at low speeds. This also provided the evidence that the central nervous system (CNS) chose a stable inter-limb coordination pattern to keep the body safe and avoid tumbling. Although considerable progress has been made in the study of four-limb locomotion, much less is known about the reasons for the variety of inter-limb coordination. The research results of the exploration on the inter-limb coordination pattern choice during crawling from the standpoint of the motion stability, intensity, and complexity of trunk and limbs sheds light on the underlying motor control strategy of the human CNS and has important significance in the fields of clinical diagnosis, rehabilitation engineering, and kinematics research. Full article

(This article belongs to the Special Issue Sensors for Ambient Assisted Living, Ubiquitous and Mobile Health)

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19 pages, 9654 KiB

Open AccessArticle

An IoT Reader for Wireless Passive Electromagnetic Sensors

by Gabriel Galindo-Romera^*

, Javier Carnerero-Cano, José Juan Martínez-Martínez and Francisco Javier Herraiz-Martínez

Department of Signal Theory and Communications, Universidad Carlos III de Madrid, Av. de la Universidad 30, 28911 Leganés, Madrid, Spain

Sensors 2017, 17(4), 693; https://doi.org/10.3390/s17040693 - 28 Mar 2017

Cited by 11 | Viewed by 11528

Abstract

In the last years, many passive electromagnetic sensors have been reported. Some of these sensors are used for measuring harmful substances. Moreover, the response of these sensors is usually obtained with laboratory equipment. This approach highly increases the total cost and complexity of [...] Read more.

In the last years, many passive electromagnetic sensors have been reported. Some of these sensors are used for measuring harmful substances. Moreover, the response of these sensors is usually obtained with laboratory equipment. This approach highly increases the total cost and complexity of the sensing system. In this work, a novel low-cost and portable Internet-of-Things (IoT) reader for passive wireless electromagnetic sensors is proposed. The reader is used to interrogate the sensors within a short-range wireless link avoiding the direct contact with the substances under test. The IoT functionalities of the reader allows remote sensing from computers and handheld devices. For that purpose, the proposed design is based on four functional layers: the radiating layer, the RF interface, the IoT mini-computer and the power unit. In this paper a demonstrator of the proposed reader is designed and manufactured. The demonstrator shows, through the remote measurement of different substances, that the proposed system can estimate the dielectric permittivity. It has been demonstrated that a linear approximation with a small error can be extracted from the reader measurements. It is remarkable that the proposed reader can be used with other type of electromagnetic sensors, which transduce the magnitude variations in the frequency domain. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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14 pages, 1748 KiB

Open AccessArticle

Automated Software Acceleration in Programmable Logic for an Efficient NFFT Algorithm Implementation: A Case Study

by Manuel Rodríguez^1,*, Eduardo Magdaleno¹, Fernando Pérez² and Cristhian García¹

¹ Department of Industrial Engineering, Universidad de La Laguna, 38203 San Cristóbal de La Laguna, Spain

² Department of Computer Engineering and Systems, Universidad de La Laguna, 38203 San Cristóbal de La Laguna, Spain

Sensors 2017, 17(4), 694; https://doi.org/10.3390/s17040694 - 28 Mar 2017

Cited by 6 | Viewed by 5139

Abstract

Non-equispaced Fast Fourier transform (NFFT) is a very important algorithm in several technological and scientific areas such as synthetic aperture radar, computational photography, medical imaging, telecommunications, seismic analysis and so on. However, its computation complexity is high. In this paper, we describe an [...] Read more.

Non-equispaced Fast Fourier transform (NFFT) is a very important algorithm in several technological and scientific areas such as synthetic aperture radar, computational photography, medical imaging, telecommunications, seismic analysis and so on. However, its computation complexity is high. In this paper, we describe an efficient NFFT implementation with a hardware coprocessor using an All-Programmable System-on-Chip (APSoC). This is a hybrid device that employs an Advanced RISC Machine (ARM) as Processing System with Programmable Logic for high-performance digital signal processing through parallelism and pipeline techniques. The algorithm has been coded in C language with pragma directives to optimize the architecture of the system. We have used the very novel Software Develop System-on-Chip (SDSoC) evelopment tool that simplifies the interface and partitioning between hardware and software. This provides shorter development cycles and iterative improvements by exploring several architectures of the global system. The computational results shows that hardware acceleration significantly outperformed the software based implementation. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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21 pages, 1283 KiB

Open AccessArticle

On Multi-Hop Decode-and-Forward Cooperative Relaying for Industrial Wireless Sensor Networks

by Yun Ai^* and Michael Cheffena

Faculty of Engineering, Norwegian University of Science and Technology (NTNU), N-2815 Gjøvik, Norway

Sensors 2017, 17(4), 695; https://doi.org/10.3390/s17040695 - 28 Mar 2017

Cited by 19 | Viewed by 4344

Abstract

Wireless sensor networks (WSNs) will play a fundamental role in the realization of Internet of Things and Industry 4.0. Arising from the presence of spatially distributed sensor nodes in a sensor network, cooperative diversity can be achieved by using the sensor nodes between [...] Read more.

Wireless sensor networks (WSNs) will play a fundamental role in the realization of Internet of Things and Industry 4.0. Arising from the presence of spatially distributed sensor nodes in a sensor network, cooperative diversity can be achieved by using the sensor nodes between a given source-destination pair as intermediate relay stations. In this paper, we investigate the end-to-end average bit error rate (BER) and the channel capacity of a multi-hop relay network in the presence of impulsive noise modeled by the well-known Middleton’s class-A model. Specifically, we consider a multi-hop decode-and-forward (DF) relay network over Nakagami-m fading channel due to its generality, but also due to the absence of reported works in this area. Closed-form analytical expressions for the end-to-end average BER and the statistical properties of the end-to-end channel capacity are obtained. The impacts of the channel parameters on these performance quantities are evaluated and discussed. Full article

(This article belongs to the Section Sensor Networks)

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15 pages, 3716 KiB

Open AccessArticle

New Particle Filter Based on GA for Equipment Remaining Useful Life Prediction

by Ke Li¹, Jingjing Wu^1,*, Qiuju Zhang¹, Lei Su¹ and Peng Chen²

¹ Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, Jiangnan University, 1800 Li Hu Avenue, Wuxi 214122, China

² Graduate School of Bioresources, Mie University/1577 Kurimamachiya-cho, Tsu, Mie 514-8507, Japan

Sensors 2017, 17(4), 696; https://doi.org/10.3390/s17040696 - 28 Mar 2017

Cited by 26 | Viewed by 5623

Abstract

Remaining useful life (RUL) prediction of equipment has important significance for guaranteeing production efficiency, reducing maintenance cost, and improving plant safety. This paper proposes a novel method based on an new particle filter (PF) for predicting equipment RUL. Genetic algorithm (GA) is employed [...] Read more.

Remaining useful life (RUL) prediction of equipment has important significance for guaranteeing production efficiency, reducing maintenance cost, and improving plant safety. This paper proposes a novel method based on an new particle filter (PF) for predicting equipment RUL. Genetic algorithm (GA) is employed to improve the particle leanness problem that arises in traditional PF algorithms, and a time-varying auto regressive (TVAR) model and Akaike Information Criterion (AIC) are integrated to establish the dynamic model for PF. Moreover, starting prediction time (SPT) detection method based on hypothesis testing theory is presented, by which SPT of equipment RUL can be adaptively detected. In order to verify the effectiveness of the methods proposed in this study, a simulation test and the accelerating fatigue test of a rolling element bearing are designed for RUL prediction. The test results show the methods proposed in this study can accurately predict the RUL of the rolling element bearing, and it performs better than the traditional PF algorithm and support vector machine (SVM) in the RUL prediction. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 1350 KiB

Open AccessArticle

Energy Efficiency of D2D Multi-User Cooperation

by Zufan Zhang^1,2

, Lu Wang¹ and Jie Zhang^1,*

¹ School of Communication and Information Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China

² Chongqing Key Laboratory of Mobile Communication, Chongqing 400065, China

Sensors 2017, 17(4), 697; https://doi.org/10.3390/s17040697 - 28 Mar 2017

Cited by 7 | Viewed by 4476

Abstract

The Device-to-Device (D2D) communication system is an important part of heterogeneous networks. It has great potential to improve spectrum efficiency, throughput and energy efficiency cooperation of multiple D2D users with the advantage of direct communication. When cooperating, D2D users expend extraordinary energy to [...] Read more.

The Device-to-Device (D2D) communication system is an important part of heterogeneous networks. It has great potential to improve spectrum efficiency, throughput and energy efficiency cooperation of multiple D2D users with the advantage of direct communication. When cooperating, D2D users expend extraordinary energy to relay data to other D2D users. Hence, the remaining energy of D2D users determines the life of the system. This paper proposes a cooperation scheme for multiple D2D users who reuse the orthogonal spectrum and are interested in the same data by aiming to solve the energy problem of D2D users. Considering both energy availability and the Signal to Noise Ratio (SNR) of each D2D user, the Kuhn-Munkres algorithm is introduced in the cooperation scheme to solve relay selection problems. Thus, the cooperation issue is transformed into a maximum weighted matching (MWM) problem. In order to enhance energy efficiency without the deterioration of Quality of Service (QoS), the link outage probability is derived according to the Shannon Equation by considering the data rate and delay. The simulation studies the relationships among the number of cooperative users, the length of shared data, the number of data packets and energy efficiency. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 2333 KiB

Open AccessArticle

Improving Observability of an Inertial System by Rotary Motions of an IMU

by Shuang Du^1,*, Wei Sun² and Yang Gao³

¹ School of Aeronautics and Astronautics, University of Electronic Science and Technology of China, Chengdu 610051, China

² School of Geomatics, Liaoning Technical University, Fuxin 123000, China

³ Department of Geomatics Engineering, the University of Calgary, Calgary, AB T2N 1N4, Canada

Sensors 2017, 17(4), 698; https://doi.org/10.3390/s17040698 - 28 Mar 2017

Cited by 28 | Viewed by 5839

Abstract

It has been identified that the inertial system is not a completely observable system in the absence of maneuvers. Although the velocity errors and the accelerometer bias in the vertical direction can be solely observable, other error states, including the attitude errors, the [...] Read more.

It has been identified that the inertial system is not a completely observable system in the absence of maneuvers. Although the velocity errors and the accelerometer bias in the vertical direction can be solely observable, other error states, including the attitude errors, the accelerometer biases in the east and north directions, and the gyro biases, are just jointly observable states with velocity measurements, which degrades the estimation accuracy of these error states. This paper proposes an innovative method to improve the system observability for a Micro-Electro-Mechanical-System (MEMS)-based Inertial Navigation System (INS) in the absence of maneuvers by rotary motions of the Inertial Measurement Unit (IMU). Three IMU rotation schemes, namely IMU continuous rotation about the X, Y and Z axes are employed. The observability is analyzed for the rotating system with a control-theoretic approach, and tests are also conducted based on a turntable to verify the improvements on the system observability by IMU rotations. Both theoretical analysis and the results indicate that the system observability is improved by proposed IMU rotations, the roll and pitch errors, the accelerometer biases in the east and north directions, the gyro biases become observable states in the absence of vehicle maneuvers. Although the azimuth error is still unobservable, the enhanced estimability of the gyro bias in the vertical direction can effectively mitigate the azimuth error accumulation. Full article

(This article belongs to the Special Issue Inertial Sensors and Systems 2016)

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10 pages, 4702 KiB

Open AccessArticle

Frequency-Switchable Microfluidic CSRR-Loaded QMSIW Band-Pass Filter Using a Liquid Metal Alloy

by Seunghyun Eom, Muhammad Usman Memon

and Sungjoon Lim^*

School of Electrical and Electronics Engineering, College of Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756, Korea

Sensors 2017, 17(4), 699; https://doi.org/10.3390/s17040699 - 28 Mar 2017

Cited by 20 | Viewed by 6964

Abstract

In this paper, we have proposed a frequency-switchable complementary split-ring resonator (CSRR)-loaded quarter-mode substrate-integrated-waveguide (QMSIW) band-pass filter. For frequency switching, a microfluidic channel and liquid metal are used. The liquid metal used is eutectic gallium-indium (EGaIn), consisting of 24.5% indium and 75.5% gallium. [...] Read more.

In this paper, we have proposed a frequency-switchable complementary split-ring resonator (CSRR)-loaded quarter-mode substrate-integrated-waveguide (QMSIW) band-pass filter. For frequency switching, a microfluidic channel and liquid metal are used. The liquid metal used is eutectic gallium-indium (EGaIn), consisting of 24.5% indium and 75.5% gallium. The microfluidic channels are built using the elastomer polydimethylsiloxane (PDMS) and three-dimensional-printed microfluidic channel frames. The CSRR-loaded QMSIW band-pass filter is designed to have two states. Before the injection of the liquid metal, the measured center frequency and fractional bandwidths are 2.205 GHz and 6.80%, respectively. After injection, the center frequency shifts from 2.205 GHz to 2.56 GHz. Although the coupling coefficient is practically unchanged, the fractional bandwidth changes from 6.8% to 9.38%, as the CSRR shape changes and the external quality factor decreases. After the removal of the liquid metal, the measured values are similar to the values recorded before the liquid metal was injected. The repeatability of the frequency-switchable mechanism is, therefore, verified. Full article

(This article belongs to the Special Issue Microfluidics-Based Microsystem Integration Research)

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14 pages, 796 KiB

Open AccessArticle

Sensor Fault and Delay Tolerant Control for Networked Control Systems Subject to External Disturbances

by Shi-Yuan Han^1,*

, Yue-Hui Chen¹ and Gong-You Tang²

¹ Shandong Provincial Key Laboratory of Network Based Intelligent Computing, University of Jinan, Jinan 250022 , China

² College of Information Science and Engineering, Ocean University of China, Qingdao 266100, China

Sensors 2017, 17(4), 700; https://doi.org/10.3390/s17040700 - 28 Mar 2017

Cited by 15 | Viewed by 4534

Abstract

In this paper, the problem of sensor fault and delay tolerant control problem for a class of networked control systems under external disturbances is investigated. More precisely, the dynamic characteristics of the external disturbance and sensor fault are described as the output of [...] Read more.

In this paper, the problem of sensor fault and delay tolerant control problem for a class of networked control systems under external disturbances is investigated. More precisely, the dynamic characteristics of the external disturbance and sensor fault are described as the output of exogenous systems first. The original sensor fault and delay tolerant control problem is reformulated as an equivalence problem with designed available system output and reformed performance index. The feedforward and feedback sensor fault tolerant controller (FFSFTC) can be obtained by utilizing the solutions of Riccati matrix equation and Stein matrix equation. Based on the designed fault diagnoser, the proposed FFSFTC is further reconstructed to compensate for the sensor fault and delayed measurement effects. Finally, numerical examples are provided to illustrate the effectiveness of our proposed FFSFTC with different cases with various types of sensor faults, measurement delays and external disturbances. Full article

(This article belongs to the Section Physical Sensors)

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23 pages, 24477 KiB

Open AccessArticle

Prioritizing Seafloor Mapping for Washington’s Pacific Coast

by Timothy Battista^1,*, Ken Buja¹, John Christensen¹, Jennifer Hennessey² and Katrina Lassiter³

¹ National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science, Silver Spring, MD 20910, USA

² Washington State Department of Ecology, Lacey, WA 98503, USA

³ Washington State Department of Natural Resources, Olympia, WA 98504, USA

Sensors 2017, 17(4), 701; https://doi.org/10.3390/s17040701 - 28 Mar 2017

Cited by 3 | Viewed by 5565

Abstract

Remote sensing systems are critical tools used for characterizing the geological and ecological composition of the seafloor. However, creating comprehensive and detailed maps of ocean and coastal environments has been hindered by the high cost of operating ship- and aircraft-based sensors. While a [...] Read more.

Remote sensing systems are critical tools used for characterizing the geological and ecological composition of the seafloor. However, creating comprehensive and detailed maps of ocean and coastal environments has been hindered by the high cost of operating ship- and aircraft-based sensors. While a number of groups (e.g., academic research, government resource management, and private sector) are engaged in or would benefit from the collection of additional seafloor mapping data, disparate priorities, dauntingly large data gaps, and insufficient funding have confounded strategic planning efforts. In this study, we addressed these challenges by implementing a quantitative, spatial process to facilitate prioritizing seafloor mapping needs in Washington State. The Washington State Prioritization Tool (WASP), a custom web-based mapping tool, was developed to solicit and analyze mapping priorities from each participating group. The process resulted in the identification of several discrete, high priority mapping hotspots. As a result, several of the areas have been or will be subsequently mapped. Furthermore, information captured during the process about the intended application of the mapping data was paramount for identifying the optimum remote sensing sensors and acquisition parameters to use during subsequent mapping surveys. Full article

(This article belongs to the Special Issue Advances in Applied Remote Sensing and Decision Making: Transforming Hazard Assessment and Environmental Management)

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14 pages, 383 KiB

Open AccessArticle

Underdetermined DOA Estimation of Quasi-Stationary Signals Using a Partly-Calibrated Array

by Ben Wang^1,2, Wei Wang^1,*, Yujie Gu² and Shujie Lei¹

¹ College of Automation, Harbin Engineering University, No. 145 Nantong Street, Harbin 150001, China

² Depaprtment of Electrical and Computer Engineering, Temple University, Philadelphia, PA 19122, USA

Sensors 2017, 17(4), 702; https://doi.org/10.3390/s17040702 - 28 Mar 2017

Cited by 23 | Viewed by 5105

Abstract

Quasi-stationary signals have been widely found in practical applications, which have time-varying second-order statistics while staying static within local time frames. In this paper, we develop a robust direction-of-arrival (DOA) estimation algorithm for quasi-stationary signals based on the Khatri–Rao (KR) subspace approach. A [...] Read more.

Quasi-stationary signals have been widely found in practical applications, which have time-varying second-order statistics while staying static within local time frames. In this paper, we develop a robust direction-of-arrival (DOA) estimation algorithm for quasi-stationary signals based on the Khatri–Rao (KR) subspace approach. A partly-calibrated array is considered, in which some of the sensors have an inaccurate knowledge of the gain and phase. In detail, we first develop a closed-form solution to estimate the unknown sensor gains and phases. The array is then calibrated using the estimated sensor gains and phases which enables the improved DOA estimation. To reduce the computational complexity, we also proposed a reduced-dimensional method for DOA estimation. The exploitation of the KR subspace approach enables the proposed method to achieve a larger number of degrees-of-freedom, i.e., more sources than sensors can be estimated. The unique identification condition for the proposed method is also derived. Simulation results demonstrate the effectiveness of the proposed underdetermined DOA estimation algorithm for quasi-stationary signals. Full article

(This article belongs to the Special Issue Recent Advances in Array Signal Processing and Its Applications in IoT Security)

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16 pages, 2970 KiB

Open AccessArticle

Trust Model of Wireless Sensor Networks and Its Application in Data Fusion

by Zhenguo Chen^1,2,*, Liqin Tian¹ and Chuang Lin³

¹ Hebei Engineering Technology Research Center for IOT Data acquisition & Processing, North China Institute of Science and Technology, East Yanjiao, Beijing 101601, China

² School of Computer Science and Engineering, Northeastern University, Shenyang 110819, China

³ Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(4), 703; https://doi.org/10.3390/s17040703 - 28 Mar 2017

Cited by 64 | Viewed by 7736

Abstract

In order to ensure the reliability and credibility of the data in wireless sensor networks (WSNs), this paper proposes a trust evaluation model and data fusion mechanism based on trust. First of all, it gives the model structure. Then, the calculation rules of [...] Read more.

In order to ensure the reliability and credibility of the data in wireless sensor networks (WSNs), this paper proposes a trust evaluation model and data fusion mechanism based on trust. First of all, it gives the model structure. Then, the calculation rules of trust are given. In the trust evaluation model, comprehensive trust consists of three parts: behavior trust, data trust, and historical trust. Data trust can be calculated by processing the sensor data. Based on the behavior of nodes in sensing and forwarding, the behavior trust is obtained. The initial value of historical trust is set to the maximum and updated with comprehensive trust. Comprehensive trust can be obtained by weighted calculation, and then the model is used to construct the trust list and guide the process of data fusion. Using the trust model, simulation results indicate that energy consumption can be reduced by an average of 15%. The detection rate of abnormal nodes is at least 10% higher than that of the lightweight and dependable trust system (LDTS) model. Therefore, this model has good performance in ensuring the reliability and credibility of the data. Moreover, the energy consumption of transmitting was greatly reduced. Full article

(This article belongs to the Special Issue Enabling the Move from Wireless Sensor Networks to Internet of Things and Cyber-Physical Systems)

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20 pages, 10679 KiB

Open AccessArticle

A Smartphone Camera-Based Indoor Positioning Algorithm of Crowded Scenarios with the Assistance of Deep CNN

by Jichao Jiao^1,*

, Fei Li¹, Zhongliang Deng¹ and Wenjing Ma²

¹ Beijing University of Posts and Telecommunications, Beijing 100088, China

² China Academy of Information and Communication Technology (CAICT), Beijing 100191, China

Sensors 2017, 17(4), 704; https://doi.org/10.3390/s17040704 - 28 Mar 2017

Cited by 50 | Viewed by 6535

Abstract

Considering the installation cost and coverage, the received signal strength indicator (RSSI)-based indoor positioning system is widely used across the world. However, the indoor positioning performance, due to the interference of wireless signals that are caused by the complex indoor environment that includes [...] Read more.

Considering the installation cost and coverage, the received signal strength indicator (RSSI)-based indoor positioning system is widely used across the world. However, the indoor positioning performance, due to the interference of wireless signals that are caused by the complex indoor environment that includes a crowded population, cannot achieve the demands of indoor location-based services. In this paper, we focus on increasing the signal strength estimation accuracy considering the population density, which is different to the other RSSI-based indoor positioning methods. Therefore, we propose a new wireless signal compensation model considering the population density, distance, and frequency. First of all, the number of individuals in an indoor crowded scenario can be calculated by our convolutional neural network (CNN)-based human detection approach. Then, the relationship between the population density and the signal attenuation is described in our model. Finally, we use the trilateral positioning principle to realize the pedestrian location. According to the simulation and tests in the crowded scenarios, the proposed model increases the accuracy of the signal strength estimation by 1.53 times compared to that without considering the human body. Therefore, the localization accuracy is less than 1.37 m, which indicates that our algorithm can improve the indoor positioning performance and is superior to other RSSI models. Full article

(This article belongs to the Special Issue Smartphone-based Pedestrian Localization and Navigation)

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15 pages, 11795 KiB

Open AccessArticle

Feasibility Study of Extended-Gate-Type Silicon Nanowire Field-Effect Transistors for Neural Recording

by Hongki Kang¹

, Jee-Yeon Kim², Yang-Kyu Choi^2,3,* and Yoonkey Nam^1,3,*

¹ Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea

² Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea

³ KAIST Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea

Sensors 2017, 17(4), 705; https://doi.org/10.3390/s17040705 - 28 Mar 2017

Cited by 8 | Viewed by 7490

Abstract

In this research, a high performance silicon nanowire field-effect transistor (transconductance as high as 34 µS and sensitivity as 84 nS/mV) is extensively studied and directly compared with planar passive microelectrode arrays for neural recording application. Electrical and electrochemical characteristics are carefully characterized [...] Read more.

In this research, a high performance silicon nanowire field-effect transistor (transconductance as high as 34 µS and sensitivity as 84 nS/mV) is extensively studied and directly compared with planar passive microelectrode arrays for neural recording application. Electrical and electrochemical characteristics are carefully characterized in a very well-controlled manner. We especially focused on the signal amplification capability and intrinsic noise of the transistors. A neural recording system using both silicon nanowire field-effect transistor-based active-type microelectrode array and platinum black microelectrode-based passive-type microelectrode array are implemented and compared. An artificial neural spike signal is supplied as input to both arrays through a buffer solution and recorded simultaneously. Recorded signal intensity by the silicon nanowire transistor was precisely determined by an electrical characteristic of the transistor, transconductance. Signal-to-noise ratio was found to be strongly dependent upon the intrinsic 1/f noise of the silicon nanowire transistor. We found how signal strength is determined and how intrinsic noise of the transistor determines signal-to-noise ratio of the recorded neural signals. This study provides in-depth understanding of the overall neural recording mechanism using silicon nanowire transistors and solid design guideline for further improvement and development. Full article

(This article belongs to the Section Biosensors)

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12 pages, 3723 KiB

Open AccessArticle

A Novel Ultrasonic Method for Liquid Level Measurement Based on the Balance of Echo Energy

by Bin Zhang^1,2, Yue-Juan Wei³, Wen-Yi Liu^1,2,*, Yan-Jun Zhang^1,2,*, Zong Yao^1,2, Liang Zhang^1,2 and Ji-Jun Xiong^1,2

¹ Key Laboratory of Instrumentation Science & Dynamic Measurement, Ministry of Education, North University of China, Taiyuan 030051, China

² Science and Technology on Electronic Test & Measurement Laboratory, North University of China, Taiyuan 030051, China

³ Software School of North University of China, Taiyuan 030051, China

Sensors 2017, 17(4), 706; https://doi.org/10.3390/s17040706 - 28 Mar 2017

Cited by 18 | Viewed by 5771

Abstract

This study presents a novel method for determining the liquid level from the outside of a sealed container, which is based on the balance of echo energy received by two receiving sensors. The proposed method uses one transmitting transducer and two receiving sensors [...] Read more.

This study presents a novel method for determining the liquid level from the outside of a sealed container, which is based on the balance of echo energy received by two receiving sensors. The proposed method uses one transmitting transducer and two receiving sensors that are encapsulated in a coupling plane and arranged by certain rules. The calculation and comparison of echo energy are grounded on the difference ultrasonic impedance between gas and liquid media. First, by analyzing the propagation and attenuation characteristics of ultrasonic waves in a solid, an acoustic model for calculating the echo energy is established and simulated in MATLAB. Second, the proposed method is evaluated through a series of experiments. The difference and ratio of echo energy received by two receiving sensors are calculated and compared under two different coupling conditions. Two kinds of the sensors that are arranged by different rules are selected for measuring the liquid level, and the measurement are analyzed and discussed in detail. Finally, the experimental results indicate that the proposed method can meet the proposed accuracy requirements and can effectively solve the problems caused by some poor coupling conditions. Full article

(This article belongs to the Section Physical Sensors)

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26 pages, 31727 KiB

Open AccessArticle

Optimization of an Optical Test Bench for Tire Properties Measurement and Tread Defects Characterization

by Juan Jesús Castillo Aguilar^*

, Juan Antonio Cabrera Carrillo

, Antonio Jesús Guerra Fernández and Sergio Postigo Pozo

Department of Mechanical Engineering, Doctor Ortiz Ramos s/n, 29071 Malaga, Spain

Sensors 2017, 17(4), 707; https://doi.org/10.3390/s17040707 - 29 Mar 2017

Cited by 17 | Viewed by 7196

Abstract

Tire characteristics and behavior are of great importance in vehicle dynamics since the forces transmitted in the tire-road contact are the main contributors to global vehicle performance. Several research groups have focused on the study and modeling of tires. Some of the most [...] Read more.

Tire characteristics and behavior are of great importance in vehicle dynamics since the forces transmitted in the tire-road contact are the main contributors to global vehicle performance. Several research groups have focused on the study and modeling of tires. Some of the most important factors that need to be known are tread characteristics and pressure distribution in the tire-ground contact patch. In this work, a test bench has been used to adequately determine the aforementioned factors. The measurement principle of the test bench is the frustration of total internal reflection (FTIR) of light. It makes use of a laterally illuminated glass on which the tire leans. An interposed plastic interface between them causes the reflection of light. Finally, a video camera captures the bright image formed through the glass. The brightness level in each pixel of the image is related to existing normal pressure. A study of the parameters that affect the test bench calibration such as type of interface material used, diffuse light, hysteresis, creep and transverse light absorption is performed. Experimental tests are conducted to relate tire inflation pressure and camber angle to the pressure distribution. Furthermore, the test bench is used to detect and evaluate the influence of defects in the tire on the contact pressures. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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25 pages, 10384 KiB

Open AccessArticle

A Coarse Alignment Method Based on Digital Filters and Reconstructed Observation Vectors

by Xiang Xu^1,2, Xiaosu Xu^1,2,*

, Tao Zhang^1,2, Yao Li^1,2 and Zhicheng Wang³

¹ Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology, Ministry of Education, Nanjing 210096, China

² School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

³ School of Information and Control, Nanjing University of Information Science and Technology, Nanjing 210044, China

Sensors 2017, 17(4), 709; https://doi.org/10.3390/s17040709 - 29 Mar 2017

Cited by 19 | Viewed by 4741

Abstract

In this paper, a coarse alignment method based on apparent gravitational motion is proposed. Due to the interference of the complex situations, the true observation vectors, which are calculated by the apparent gravity, are contaminated. The sources of the interference are analyzed in [...] Read more.

In this paper, a coarse alignment method based on apparent gravitational motion is proposed. Due to the interference of the complex situations, the true observation vectors, which are calculated by the apparent gravity, are contaminated. The sources of the interference are analyzed in detail, and then a low-pass digital filter is designed in this paper for eliminating the high-frequency noise of the measurement observation vectors. To extract the effective observation vectors from the inertial sensors’ outputs, a parameter recognition and vector reconstruction method are designed, where an adaptive Kalman filter is employed to estimate the unknown parameters. Furthermore, a robust filter, which is based on Huber’s M-estimation theory, is developed for addressing the outliers of the measurement observation vectors due to the maneuver of the vehicle. A comprehensive experiment, which contains a simulation test and physical test, is designed to verify the performance of the proposed method, and the results show that the proposed method is equivalent to the popular apparent velocity method in swaying mode, but it is superior to the current methods while in moving mode when the strapdown inertial navigation system (SINS) is under entirely self-contained conditions. Full article

(This article belongs to the Special Issue Inertial Sensors and Systems 2016)

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11 pages, 3047 KiB

Open AccessArticle

Gas Sensor Based on 3-D WO₃ Inverse Opal: Design and Applications

by Ruiqing Xing^1,2,*, Yang Du^1,2, Xiaonan Zhao^1,2 and Xiu Zhang^1,2

¹ Tianjin Key laboratory of Wireless Mobile Communications and Power Transmission, Tianjin Normal University, Tianjin 300387, China

² College of Electronic and Communication Engineering, Tianjin Normal University, Tianjin 300387, China

Sensors 2017, 17(4), 710; https://doi.org/10.3390/s17040710 - 29 Mar 2017

Cited by 21 | Viewed by 8299

Abstract

A three-dimensional inverse opal (3DIO) WO₃ architecture has been synthesized via a simple sacrificial template method. Morphology features of the 3DIO were characterized by scanning electron microscope (SEM) and its structure was characterized by X-ray diffraction (XRD). The shrinking ratio of the [...] Read more.

A three-dimensional inverse opal (3DIO) WO₃ architecture has been synthesized via a simple sacrificial template method. Morphology features of the 3DIO were characterized by scanning electron microscope (SEM) and its structure was characterized by X-ray diffraction (XRD). The shrinking ratio of the PMMA spheres was ~28.2% through measuring the distribution of the PMMA spheres and 3DIO WO₃ center-to-center distance between the spheres and macropores, respectively. Beyond that, the 3DIO gas sensing properties were investigated systematically and the sensing mechanism of 3DIO WO₃ was proposed. The results indicated that the response of the 3DIO sensor possessed excellent sensitivity to acetone gas, especially at trace levels. The 3DIO gas sensor response was ~7 to 5 ppm of acetone and could detect acetone low to 0.2 ppm effectively, which was in close proximity to the theoretical low detection limit of 0.14 ppm when R_a/R_g ≥ 1.2 was used as the criterion for reliable gas sensing. All in all, the obvious satisfaction of the gas-sensing properties was ascribed to the structure of the 3DIO, and the sensor could be a promising novel device in the future. Full article

(This article belongs to the Collection Gas Sensors)

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28 pages, 6453 KiB

Open AccessArticle

A Cardiac Early Warning System with Multi Channel SCG and ECG Monitoring for Mobile Health

by Prasan Kumar Sahoo^1,2

, Hiren Kumar Thakkar¹

and Ming-Yih Lee^2,3,*

¹ Department of Computer Science and Information Engineering, Chang Gung University, Taoyuan City 33302, Taiwan

² Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Taoyuan City 33305, Taiwan

³ Graduate Institute of Medical Mechatronics, Center for Biomedical Engineering, Chang Gung University, Taoyuan City 33302, Taiwan

Sensors 2017, 17(4), 711; https://doi.org/10.3390/s17040711 - 29 Mar 2017

Cited by 71 | Viewed by 13295

Abstract

Use of information and communication technology such as smart phone, smart watch, smart glass and portable health monitoring devices for healthcare services has made Mobile Health (mHealth) an emerging research area. Coronary Heart Disease (CHD) is considered as a leading cause of death [...] Read more.

Use of information and communication technology such as smart phone, smart watch, smart glass and portable health monitoring devices for healthcare services has made Mobile Health (mHealth) an emerging research area. Coronary Heart Disease (CHD) is considered as a leading cause of death world wide and an increasing number of people die prematurely due to CHD. Under such circumstances, there is a growing demand for a reliable cardiac monitoring system to catch the intermittent abnormalities and detect critical cardiac behaviors which lead to sudden death. Use of mobile devices to collect Electrocardiography (ECG), Seismocardiography (SCG) data and efficient analysis of those data can monitor a patient’s cardiac activities for early warning. This paper presents a novel cardiac data acquisition method and combined analysis of Electrocardiography (ECG) and multi channel Seismocardiography (SCG) data. An early warning system is implemented to monitor the cardiac activities of a person and accuracy assessment of the early warning system is conducted for the ECG data only. The assessment shows 88% accuracy and effectiveness of our proposed analysis, which implies the viability and applicability of the proposed early warning system. Full article

(This article belongs to the Special Issue Sensors for Ambient Assisted Living, Ubiquitous and Mobile Health)

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18 pages, 1677 KiB

Open AccessArticle

Facial Expression Recognition with Fusion Features Extracted from Salient Facial Areas

by Yanpeng Liu, Yibin Li, Xin Ma and Rui Song^*

School of Control Science and Engineering, Shandong University, Jinan 250061, China

Sensors 2017, 17(4), 712; https://doi.org/10.3390/s17040712 - 29 Mar 2017

Cited by 91 | Viewed by 9212

Abstract

In the pattern recognition domain, deep architectures are currently widely used and they have achieved fine results. However, these deep architectures make particular demands, especially in terms of their requirement for big datasets and GPU. Aiming to gain better results without deep networks, [...] Read more.

In the pattern recognition domain, deep architectures are currently widely used and they have achieved fine results. However, these deep architectures make particular demands, especially in terms of their requirement for big datasets and GPU. Aiming to gain better results without deep networks, we propose a simplified algorithm framework using fusion features extracted from the salient areas of faces. Furthermore, the proposed algorithm has achieved a better result than some deep architectures. For extracting more effective features, this paper firstly defines the salient areas on the faces. This paper normalizes the salient areas of the same location in the faces to the same size; therefore, it can extracts more similar features from different subjects. LBP and HOG features are extracted from the salient areas, fusion features’ dimensions are reduced by Principal Component Analysis (PCA) and we apply several classifiers to classify the six basic expressions at once. This paper proposes a salient areas definitude method which uses peak expressions frames compared with neutral faces. This paper also proposes and applies the idea of normalizing the salient areas to align the specific areas which express the different expressions. As a result, the salient areas found from different subjects are the same size. In addition, the gamma correction method is firstly applied on LBP features in our algorithm framework which improves our recognition rates significantly. By applying this algorithm framework, our research has gained state-of-the-art performances on CK+ database and JAFFE database. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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26 pages, 13244 KiB

Open AccessFeature PaperArticle

Model-Based Estimation of Ankle Joint Stiffness

by Berno J. E. Misgeld^*, Tony Zhang, Markus J. Lüken and Steffen Leonhardt

Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany

Sensors 2017, 17(4), 713; https://doi.org/10.3390/s17040713 - 29 Mar 2017

Cited by 17 | Viewed by 8238

Abstract

We address the estimation of biomechanical parameters with wearable measurement technologies. In particular, we focus on the estimation of sagittal plane ankle joint stiffness in dorsiflexion/plantar flexion. For this estimation, a novel nonlinear biomechanical model of the lower leg was formulated that is [...] Read more.

We address the estimation of biomechanical parameters with wearable measurement technologies. In particular, we focus on the estimation of sagittal plane ankle joint stiffness in dorsiflexion/plantar flexion. For this estimation, a novel nonlinear biomechanical model of the lower leg was formulated that is driven by electromyographic signals. The model incorporates a two-dimensional kinematic description in the sagittal plane for the calculation of muscle lever arms and torques. To reduce estimation errors due to model uncertainties, a filtering algorithm is necessary that employs segmental orientation sensor measurements. Because of the model’s inherent nonlinearities and nonsmooth dynamics, a square-root cubature Kalman filter was developed. The performance of the novel estimation approach was evaluated in silico and in an experimental procedure. The experimental study was conducted with body-worn sensors and a test-bench that was specifically designed to obtain reference angle and torque measurements for a single joint. Results show that the filter is able to reconstruct joint angle positions, velocities and torque, as well as, joint stiffness during experimental test bench movements. Full article

(This article belongs to the Special Issue Wearable Biomedical Sensors)

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10 pages, 3642 KiB

Open AccessArticle

A Self-Sustained Wireless Multi-Sensor Platform Integrated with Printable Organic Sensors for Indoor Environmental Monitoring

by Chun-Chang Wu¹

, Wen-Yu Chuang¹, Ching-Da Wu¹, Yu-Cheng Su¹, Yung-Yang Huang¹, Yang-Jing Huang², Sheng-Yu Peng², Shih-An Yu¹, Chih-Ting Lin¹ and Shey-Shi Lu^1,*

¹ Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan

² Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei 10617, Taiwan

Sensors 2017, 17(4), 715; https://doi.org/10.3390/s17040715 - 29 Mar 2017

Cited by 9 | Viewed by 9126

Abstract

A self-sustained multi-sensor platform for indoor environmental monitoring is proposed in this paper. To reduce the cost and power consumption of the sensing platform, in the developed platform, organic materials of PEDOT:PSS and PEDOT:PSS/EB-PANI are used as the sensing films for humidity and [...] Read more.

A self-sustained multi-sensor platform for indoor environmental monitoring is proposed in this paper. To reduce the cost and power consumption of the sensing platform, in the developed platform, organic materials of PEDOT:PSS and PEDOT:PSS/EB-PANI are used as the sensing films for humidity and CO₂ detection, respectively. Different from traditional gas sensors, these organic sensing films can operate at room temperature without heating processes or infrared transceivers so that the power consumption of the developed humidity and the CO₂ sensors can be as low as 10 μW and 5 μW, respectively. To cooperate with these low-power sensors, a Complementary Metal-Oxide-Semiconductor (CMOS) system-on-chip (SoC) is designed to amplify and to read out multiple sensor signals with low power consumption. The developed SoC includes an analog-front-end interface circuit (AFE), an analog-to-digital convertor (ADC), a digital controller and a power management unit (PMU). Scheduled by the digital controller, the sensing circuits are power gated with a small duty-cycle to reduce the average power consumption to 3.2 μW. The designed PMU converts the power scavenged from a dye sensitized solar cell (DSSC) module into required supply voltages for SoC circuits operation under typical indoor illuminance conditions. To our knowledge, this is the first multiple environmental parameters (Temperature/CO₂/Humidity) sensing platform that demonstrates a true self-powering functionality for long-term operations. Full article

(This article belongs to the Special Issue Self-Powered Sensors)

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24 pages, 1401 KiB

Open AccessArticle

Modeling and Density Estimation of an Urban Freeway Network Based on Dynamic Graph Hybrid Automata

by Yangzhou Chen^*, Yuqi Guo

and Ying Wang

College of Metropolitan Transportation, Beijing University of Technology, Beijing 100124, China

Sensors 2017, 17(4), 716; https://doi.org/10.3390/s17040716 - 29 Mar 2017

Cited by 18 | Viewed by 6033

Abstract

In this paper, in order to describe complex network systems, we firstly propose a general modeling framework by combining a dynamic graph with hybrid automata and thus name it Dynamic Graph Hybrid Automata (DGHA). Then we apply this framework to model traffic flow [...] Read more.

In this paper, in order to describe complex network systems, we firstly propose a general modeling framework by combining a dynamic graph with hybrid automata and thus name it Dynamic Graph Hybrid Automata (DGHA). Then we apply this framework to model traffic flow over an urban freeway network by embedding the Cell Transmission Model (CTM) into the DGHA. With a modeling procedure, we adopt a dual digraph of road network structure to describe the road topology, use linear hybrid automata to describe multi-modes of dynamic densities in road segments and transform the nonlinear expressions of the transmitted traffic flow between two road segments into piecewise linear functions in terms of multi-mode switchings. This modeling procedure is modularized and rule-based, and thus is easily-extensible with the help of a combination algorithm for the dynamics of traffic flow. It can describe the dynamics of traffic flow over an urban freeway network with arbitrary topology structures and sizes. Next we analyze mode types and number in the model of the whole freeway network, and deduce a Piecewise Affine Linear System (PWALS) model. Furthermore, based on the PWALS model, a multi-mode switched state observer is designed to estimate the traffic densities of the freeway network, where a set of observer gain matrices are computed by using the Lyapunov function approach. As an example, we utilize the PWALS model and the corresponding switched state observer to traffic flow over Beijing third ring road. In order to clearly interpret the principle of the proposed method and avoid computational complexity, we adopt a simplified version of Beijing third ring road. Practical application for a large-scale road network will be implemented by decentralized modeling approach and distributed observer designing in the future research. Full article

(This article belongs to the Special Issue Sensors for Transportation)

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39 pages, 8788 KiB

Open AccessArticle

An Improved Approach for RSSI-Based only Calibration-Free Real-Time Indoor Localization on IEEE 802.11 and 802.15.4 Wireless Networks

by Marco Passafiume^*

, Stefano Maddio

and Alessandro Cidronali

Department of Information Engineering, University of Florence, Florence 50139, Italy

Sensors 2017, 17(4), 717; https://doi.org/10.3390/s17040717 - 29 Mar 2017

Cited by 43 | Viewed by 9298

Abstract

Assuming a reliable and responsive spatial contextualization service is a must-have in IEEE 802.11 and 802.15.4 wireless networks, a suitable approach consists of the implementation of localization capabilities, as an additional application layer to the communication protocol stack. Considering the applicative scenario where [...] Read more.

Assuming a reliable and responsive spatial contextualization service is a must-have in IEEE 802.11 and 802.15.4 wireless networks, a suitable approach consists of the implementation of localization capabilities, as an additional application layer to the communication protocol stack. Considering the applicative scenario where satellite-based positioning applications are denied, such as indoor environments, and excluding data packet arrivals time measurements due to lack of time resolution, received signal strength indicator (RSSI) measurements, obtained according to IEEE 802.11 and 802.15.4 data access technologies, are the unique data sources suitable for indoor geo-referencing using COTS devices. In the existing literature, many RSSI based localization systems are introduced and experimentally validated, nevertheless they require periodic calibrations and significant information fusion from different sensors that dramatically decrease overall systems reliability and their effective availability. This motivates the work presented in this paper, which introduces an approach for an RSSI-based calibration-free and real-time indoor localization. While switched-beam array-based hardware (compliant with IEEE 802.15.4 router functionality) has already been presented by the author, the focus of this paper is the creation of an algorithmic layer for use with the pre-existing hardware capable to enable full localization and data contextualization over a standard 802.15.4 wireless sensor network using only RSSI information without the need of lengthy offline calibration phase. System validation reports the localization results in a typical indoor site, where the system has shown high accuracy, leading to a sub-metrical overall mean error and an almost 100% site coverage within 1 m localization error. Full article

(This article belongs to the Special Issue Sensors and Sensing in Indoor Localization, Tracking, Navigation and Activity Monitoring)

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18 pages, 1468 KiB

Open AccessArticle

Posture Detection Based on Smart Cushion for Wheelchair Users

by Congcong Ma¹

, Wenfeng Li^1,*, Raffaele Gravina² and Giancarlo Fortino²

¹ School of Logistics Engineering, Wuhan University of Technology, Wuhan, 430070, China

² Department of Informatics, Modeling, Electronics and Systems, University of Calabria, Rende, 87036, Italy

Sensors 2017, 17(4), 719; https://doi.org/10.3390/s17040719 - 29 Mar 2017

Cited by 107 | Viewed by 15286

Abstract

The postures of wheelchair users can reveal their sitting habit, mood, and even predict health risks such as pressure ulcers or lower back pain. Mining the hidden information of the postures can reveal their wellness and general health conditions. In this paper, a [...] Read more.

The postures of wheelchair users can reveal their sitting habit, mood, and even predict health risks such as pressure ulcers or lower back pain. Mining the hidden information of the postures can reveal their wellness and general health conditions. In this paper, a cushion-based posture recognition system is used to process pressure sensor signals for the detection of user’s posture in the wheelchair. The proposed posture detection method is composed of three main steps: data level classification for posture detection, backward selection of sensor configuration, and recognition results compared with previous literature. Five supervised classification techniques—Decision Tree (J48), Support Vector Machines (SVM), Multilayer Perceptron (MLP), Naive Bayes, and k-Nearest Neighbor (k-NN)—are compared in terms of classification accuracy, precision, recall, and F-measure. Results indicate that the J48 classifier provides the highest accuracy compared to other techniques. The backward selection method was used to determine the best sensor deployment configuration of the wheelchair. Several kinds of pressure sensor deployments are compared and our new method of deployment is shown to better detect postures of the wheelchair users. Performance analysis also took into account the Body Mass Index (BMI), useful for evaluating the robustness of the method across individual physical differences. Results show that our proposed sensor deployment is effective, achieving 99.47% posture recognition accuracy. Our proposed method is very competitive for posture recognition and robust in comparison with other former research. Accurate posture detection represents a fundamental basic block to develop several applications, including fatigue estimation and activity level assessment. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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28 pages, 16304 KiB

Open AccessArticle

A Data-Driven Diagnostic Framework for Wind Turbine Structures: A Holistic Approach

by Simona Bogoevska¹, Minas Spiridonakos², Eleni Chatzi^2,*

, Elena Dumova-Jovanoska¹ and Rudiger Höffer³

¹ Faculty of Civil Engineering, University Ss. Cyril and Methodius, Skopje 1000, Macedonia

² Department of Civil, Environmental and Geomatic Engineering, ETH, Zürich CH-8093, Switzerland

³ Department of Civil and Environmental Engineering, Ruhr-University Bochum, Bochum 44801, Germany

Sensors 2017, 17(4), 720; https://doi.org/10.3390/s17040720 - 30 Mar 2017

Cited by 53 | Viewed by 7694

Abstract

The complex dynamics of operational wind turbine (WT) structures challenges the applicability of existing structural health monitoring (SHM) strategies for condition assessment. At the center of Europe’s renewable energy strategic planning, WT systems call for implementation of strategies that may describe the WT [...] Read more.

The complex dynamics of operational wind turbine (WT) structures challenges the applicability of existing structural health monitoring (SHM) strategies for condition assessment. At the center of Europe’s renewable energy strategic planning, WT systems call for implementation of strategies that may describe the WT behavior in its complete operational spectrum. The framework proposed in this paper relies on the symbiotic treatment of acting environmental/operational variables and the monitored vibration response of the structure. The approach aims at accurate simulation of the temporal variability characterizing the WT dynamics, and subsequently at the tracking of the evolution of this variability in a longer-term horizon. The bi-component analysis tool is applied on long-term data, collected as part of continuous monitoring campaigns on two actual operating WT structures located in different sites in Germany. The obtained data-driven structural models verify the potential of the proposed strategy for development of an automated SHM diagnostic tool. Full article

(This article belongs to the Special Issue System-Integrated Intelligence and Intelligent Systems)

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20 pages, 575 KiB

Open AccessArticle

Sensing Attribute Weights: A Novel Basic Belief Assignment Method

by Wen Jiang^*

, Miaoyan Zhuang, Chunhe Xie and Jun Wu

School of Electronics and Information, Northwestern Polytechnical University, Xi’an 710072, China

Sensors 2017, 17(4), 721; https://doi.org/10.3390/s17040721 - 30 Mar 2017

Cited by 23 | Viewed by 5247

Abstract

Dempster–Shafer evidence theory is widely used in many soft sensors data fusion systems on account of its good performance for handling the uncertainty information of soft sensors. However, how to determine basic belief assignment (BBA) is still an open issue. The existing methods [...] Read more.

Dempster–Shafer evidence theory is widely used in many soft sensors data fusion systems on account of its good performance for handling the uncertainty information of soft sensors. However, how to determine basic belief assignment (BBA) is still an open issue. The existing methods to determine BBA do not consider the reliability of each attribute; at the same time, they cannot effectively determine BBA in the open world. In this paper, based on attribute weights, a novel method to determine BBA is proposed not only in the closed world, but also in the open world. The Gaussian model of each attribute is built using the training samples firstly. Second, the similarity between the test sample and the attribute model is measured based on the Gaussian membership functions. Then, the attribute weights are generated using the overlap degree among the classes. Finally, BBA is determined according to the sensed attribute weights. Several examples with small datasets show the validity of the proposed method. Full article

(This article belongs to the Special Issue Soft Sensors and Intelligent Algorithms for Data Fusion)

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11 pages, 3225 KiB

Open AccessArticle

RAGE Plays a Role in LPS-Induced NF-κB Activation and Endothelial Hyperpermeability

by Liqun Wang¹, Jie Wu², Xiaohua Guo³, Xuliang Huang³ and Qiaobing Huang^3,*

¹ Drug Discovery Research Center, Southwest Medical University, 319 Zhongshan Road, Luzhou 646000, China

² First Clinical College of Medicine, Southern Medical University, Guangzhou 510515, China

³ Department of Pathophysiology, Key Lab for Shock and Microcirculation Research, Southern Medical University, Guangzhou 510515, China

Sensors 2017, 17(4), 722; https://doi.org/10.3390/s17040722 - 30 Mar 2017

Cited by 55 | Viewed by 8191

Abstract

Endothelial functional dysregulation and barrier disruption contribute to the initiation and development of sepsis. The receptor for advanced glycation end products (RAGE) has been demonstrated to be involved in the pathogenesis of sepsis. The present study aimed to investigate the role of RAGE [...] Read more.

Endothelial functional dysregulation and barrier disruption contribute to the initiation and development of sepsis. The receptor for advanced glycation end products (RAGE) has been demonstrated to be involved in the pathogenesis of sepsis. The present study aimed to investigate the role of RAGE in lipopolysaccharide (LPS)-induced nuclear factor-κB (NF-κB) activation in endothelial cells and the consequent endothelial hyperpermeability. LPS-induced upregulation of RAGE protein expression in human umbilical vein endothelial cells (HUVECs) was detected by western blotting. Activation of NF-κB was revealed using western blotting and immunofluorescent staining. LPS-elicited endothelial hyperpermeability was explored by transendothelial electrical resistance (TER) assay and endothelial monolayer permeability assay. The blocking antibody specific to RAGE was used to confirm the role of RAGE in LPS-mediated NF-κB activation and endothelial barrier disruption. We found that LPS upregulated the protein expression of RAGE in a dose- and time-dependent manner in HUVECs. Moreover, LPS triggered a significant phosphorylation and degradation of IκBα, as well as NF-κB p65 nuclear translocation. Moreover, we observed a significant increase in endothelial permeability after LPS treatment. However, the RAGE blocking antibody attenuated LPS-evoked NF-κB activation and endothelial hyperpermeability. Our results suggest that RAGE plays an important role in LPS-induced NF-κB activation and endothelial barrier dysfunction. Full article

(This article belongs to the Special Issue Sensors for Glycoproteins and Glycated Proteins)

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12 pages, 518 KiB

Open AccessArticle

An Exact Model-Based Method for Near-Field Sources Localization with Bistatic MIMO System

by Parth Raj Singh

, Yide Wang^*

and Pascal Chargé

Institute of Electronics and Telecommunications of Rennes (IETR), UMR CNRS 6164, Polytech Nantes, Rue Christian Pauc, BP 50609, 44306 Nantes CEDEX 3, France

Sensors 2017, 17(4), 723; https://doi.org/10.3390/s17040723 - 30 Mar 2017

Cited by 9 | Viewed by 4482

Abstract

In this paper, we propose an exact model-based method for near-field sources localization with a bistatic multiple input, multiple output (MIMO) radar system, and compare it with an approximated model-based method. The aim of this paper is to propose an efficient way to [...] Read more.

In this paper, we propose an exact model-based method for near-field sources localization with a bistatic multiple input, multiple output (MIMO) radar system, and compare it with an approximated model-based method. The aim of this paper is to propose an efficient way to use the exact model of the received signals of near-field sources in order to eliminate the systematic error introduced by the use of approximated model in most existing near-field sources localization techniques. The proposed method uses parallel factor (PARAFAC) decomposition to deal with the exact model. Thanks to the exact model, the proposed method has better precision and resolution than the compared approximated model-based method. The simulation results show the performance of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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32 pages, 10055 KiB

Open AccessArticle

Preserving Source Location Privacy for Energy Harvesting WSNs

by Changqin Huang¹, Ming Ma^2,3, Yuxin Liu^2,*

and Anfeng Liu²

¹ School of Information Technology in Education, South China Normal University, Guangzhou 510631, China

² School of Information Science and Engineering, Central South University, Changsha 410083, China

³ Department of Computer Science, Stony Brook University, New York, NY 11794, USA

Sensors 2017, 17(4), 724; https://doi.org/10.3390/s17040724 - 30 Mar 2017

Cited by 39 | Viewed by 5781

Abstract

Fog (From cOre to edGe) computing employs a huge number of wireless embedded devices to enable end users with anywhere-anytime-to-anything connectivity. Due to their operating nature, wireless sensor nodes often work unattended, and hence are exposed to a variety of attacks. Preserving source-location [...] Read more.

Fog (From cOre to edGe) computing employs a huge number of wireless embedded devices to enable end users with anywhere-anytime-to-anything connectivity. Due to their operating nature, wireless sensor nodes often work unattended, and hence are exposed to a variety of attacks. Preserving source-location privacy plays a key role in some wireless sensor network (WSN) applications. In this paper, a redundancy branch convergence-based preserved source location privacy scheme (RBCPSLP) is proposed for energy harvesting sensor networks, with the following advantages: numerous routing branches are created in non-hotspot areas with abundant energy, and those routing branches can merge into a few routing paths before they reach the hotspot areas. The generation time, the duration of routing, and the number of routing branches are then decided independently based on the amount of energy obtained, so as to maximize network energy utilization, greatly enhance privacy protection, and provide long network lifetimes. Theoretical analysis and experimental results show that the RBCPSLP scheme allows a several-fold improvement of the network energy utilization as well as the source location privacy preservation, while maximizing network lifetimes. Full article

(This article belongs to the Special Issue Security and Privacy Challenges in Emerging Fog Computing)

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13 pages, 16512 KiB

Open AccessArticle

The Electrochemical Behavior of Carbon Fiber Microelectrodes Modified with Carbon Nanotubes Using a Two-Step Electroless Plating/Chemical Vapor Deposition Process

by Longsheng Lu^1,2,*

, Linsheng Liang¹, Kwok Siong Teh^2,3, Yingxi Xie^1,2, Zhenping Wan¹ and Yong Tang¹

¹ School of Mechanical & Automotive Engineering, South China University of Technology, 381# Wushan Road, Guangzhou 510641, China

² Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA

³ School of Engineering, San Francisco State University, San Francisco, CA 94132, USA

Sensors 2017, 17(4), 725; https://doi.org/10.3390/s17040725 - 30 Mar 2017

Cited by 24 | Viewed by 8355

Abstract

Carbon fiber microelectrode (CFME) has been extensively applied in the biosensor and chemical sensor domains. In order to improve the electrochemical activity and sensitivity of the CFME, a new CFME modified with carbon nanotubes (CNTs), denoted as CNTs/CFME, was fabricated and investigated. First, [...] Read more.

Carbon fiber microelectrode (CFME) has been extensively applied in the biosensor and chemical sensor domains. In order to improve the electrochemical activity and sensitivity of the CFME, a new CFME modified with carbon nanotubes (CNTs), denoted as CNTs/CFME, was fabricated and investigated. First, carbon fiber (CF) monofilaments grafted with CNTs (simplified as CNTs/CFs) were fabricated in two key steps: (i) nickel electroless plating, followed by (ii) chemical vapor deposition (CVD). Second, a single CNTs/CF monofilament was selected and encapsulated into a CNTs/CFME with a simple packaging method. The morphologies of as-prepared CNTs/CFs were characterized by scanning electron microscopy. The electrochemical properties of CNTs/CFMEs were measured in potassium ferrocyanide solution (K₄Fe(CN)₆), by using a cyclic voltammetry (CV) and a chronoamperometry method. Compared with a bare CFME, a CNTs/CFME showed better CV curves with a higher distinguishable redox peak and response current; the higher the CNT content was, the better the CV curves were. Because the as-grown CNTs significantly enhanced the effective electrode area of CNTs/CFME, the contact area between the electrode and reactant was enlarged, further increasing the electrocatalytic active site density. Furthermore, the modified microelectrode displayed almost the same electrochemical behavior after 104 days, exhibiting remarkable stability and outstanding reproducibility. Full article

(This article belongs to the Special Issue Advanced Sensors Based on Carbon Electrodes)

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24 pages, 3095 KiB

Open AccessArticle

A Two-Phase Time Synchronization-Free Localization Algorithm for Underwater Sensor Networks

by Junhai Luo^*

and Liying Fan

School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China

Sensors 2017, 17(4), 726; https://doi.org/10.3390/s17040726 - 30 Mar 2017

Cited by 39 | Viewed by 5548

Abstract

Underwater Sensor Networks (UWSNs) can enable a broad range of applications such as resource monitoring, disaster prevention, and navigation-assistance. Sensor nodes location in UWSNs is an especially relevant topic. Global Positioning System (GPS) information is not suitable for use in UWSNs because of [...] Read more.

Underwater Sensor Networks (UWSNs) can enable a broad range of applications such as resource monitoring, disaster prevention, and navigation-assistance. Sensor nodes location in UWSNs is an especially relevant topic. Global Positioning System (GPS) information is not suitable for use in UWSNs because of the underwater propagation problems. Hence, some localization algorithms based on the precise time synchronization between sensor nodes that have been proposed for UWSNs are not feasible. In this paper, we propose a localization algorithm called Two-Phase Time Synchronization-Free Localization Algorithm (TP-TSFLA). TP-TSFLA contains two phases, namely, range-based estimation phase and range-free evaluation phase. In the first phase, we address a time synchronization-free localization scheme based on the Particle Swarm Optimization (PSO) algorithm to obtain the coordinates of the unknown sensor nodes. In the second phase, we propose a Circle-based Range-Free Localization Algorithm (CRFLA) to locate the unlocalized sensor nodes which cannot obtain the location information through the first phase. In the second phase, sensor nodes which are localized in the first phase act as the new anchor nodes to help realize localization. Hence, in this algorithm, we use a small number of mobile beacons to help obtain the location information without any other anchor nodes. Besides, to improve the precision of the range-free method, an extension of CRFLA achieved by designing a coordinate adjustment scheme is updated. The simulation results show that TP-TSFLA can achieve a relative high localization ratio without time synchronization. Full article

(This article belongs to the Special Issue Advances and Challenges in Underwater Sensor Networks)

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22 pages, 1479 KiB

Open AccessArticle

Acoustic NLOS Identification Using Acoustic Channel Characteristics for Smartphone Indoor Localization

by Lei Zhang¹, Danjie Huang¹, Xinheng Wang²

, Christian Schindelhauer³

and Zhi Wang^1,*

¹ State Key Laboratory of Industrial Control Technology, Zhejiang University, Hangzhou 310027, China

² School of Engineering and Computing, University of the West of Scotland, Paisley PA1 2BE, UK

³ Department of Computer Science, University of Freiburg, 79110 Freiburg, Germany

Sensors 2017, 17(4), 727; https://doi.org/10.3390/s17040727 - 30 Mar 2017

Cited by 36 | Viewed by 6259

Abstract

As the demand for indoor localization is increasing to support our daily life in large and complex indoor environments, sound-based localization technologies have attracted researchers’ attention because they have the advantages of being fully compatible with commercial off-the-shelf (COTS) smartphones, they have high [...] Read more.

As the demand for indoor localization is increasing to support our daily life in large and complex indoor environments, sound-based localization technologies have attracted researchers’ attention because they have the advantages of being fully compatible with commercial off-the-shelf (COTS) smartphones, they have high positioning accuracy and low-cost infrastructure. However, the non-line-of-sight (NLOS) phenomenon poses a great challenge and has become the technology bottleneck for practical applications of acoustic smartphone indoor localization. Through identifying and discarding the NLOS measurements, the positioning performance can be improved by incorporating only the LOS measurements. In this paper, we focus on identifying NLOS components by characterizing the acoustic channels. Firstly, by analyzing indoor acoustic propagations, the changes of acoustic channel from the line-of-sight (LOS) condition to the NLOS condition are characterized as the difference of channel gain and channel delay between the two propagation scenarios. Then, an efficient approach to estimate relative channel gain and delay based on the cross-correlation method is proposed, which considers the mitigation of the Doppler Effect and reduction of the computational complexity. Nine novel features have been extracted, and a support vector machine (SVM) classifier with a radial-based function (RBF) kernel is used to realize NLOS identification. The experimental result with an overall 98.9% classification accuracy based on a data set with more than 10 thousand measurements shows that the proposed identification approach and features are effective in acoustic NLOS identification for acoustic indoor localization via a smartphone. In order to further evaluate the performance of the proposed SVM classifier, the performance of an SVM classifier is compared with that of traditional classifiers based on logistic regression (LR) and linear discriminant analysis (LDA). The results also show that a SVM with the RBF kernel function method outperforms others in acoustic NLOS identification. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 603 KiB

Open AccessArticle

Energy-Efficient Channel Coding Strategy for Underwater Acoustic Networks

by Grasielli Barreto¹, Daniel H. Simão², Marcelo E. Pellenz^1,*

, Richard D. Souza³

, Edgard Jamhour¹, Manoel C. Penna¹, Glauber Brante² and Bruno S. Chang²

¹ Postgraduate Program in Computer Science (PPGIa), Pontifical Catholic University of Parana, Paraná 80215-901, Curitiba, Brazil

² Graduate Program in Electrical and Computer Engineering (CPGEI), Federal University of Technology, Paraná 80230-901, Curitiba, Brazil

³ Department of Electrical Engineering, Federal University of Santa Catarina, Santa Catarina 88040-900, Florianópolis, Brazil

Sensors 2017, 17(4), 728; https://doi.org/10.3390/s17040728 - 31 Mar 2017

Cited by 7 | Viewed by 5187

Abstract

Underwater acoustic networks (UAN) allow for efficiently exploiting and monitoring the sub-aquatic environment. These networks are characterized by long propagation delays, error-prone channels and half-duplex communication. In this paper, we address the problem of energy-efficient communication through the use of optimized channel coding [...] Read more.

Underwater acoustic networks (UAN) allow for efficiently exploiting and monitoring the sub-aquatic environment. These networks are characterized by long propagation delays, error-prone channels and half-duplex communication. In this paper, we address the problem of energy-efficient communication through the use of optimized channel coding parameters. We consider a two-layer encoding scheme employing forward error correction (FEC) codes and fountain codes (FC) for UAN scenarios without feedback channels. We model and evaluate the energy consumption of different channel coding schemes for a K-distributed multipath channel. The parameters of the FEC encoding layer are optimized by selecting the optimal error correction capability and the code block size. The results show the best parameter choice as a function of the link distance and received signal-to-noise ratio. Full article

(This article belongs to the Special Issue Advances and Challenges in Underwater Sensor Networks)

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15 pages, 8321 KiB

Open AccessArticle

The Use of Phononic Crystals to Design Piezoelectric Power Transducers

by Silvia Ronda¹, José Luis Aragón², Elvira Iglesias¹ and Francisco Montero de Espinosa^1,*

¹ ITEFI-CSIC, Serrano 144, 28006 Madrid, Spain

² Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Apartado Postal 1-1010, Querétaro 76230, Mexico

Sensors 2017, 17(4), 729; https://doi.org/10.3390/s17040729 - 31 Mar 2017

Cited by 13 | Viewed by 5881

Abstract

It was recently proposed that the lateral resonances around the working resonance band of ultrasonic piezoelectric sandwich transducers can be stopped by a periodic array of circular holes drilled along the main propagation direction (a phononic crystal). In this work, the performance of [...] Read more.

It was recently proposed that the lateral resonances around the working resonance band of ultrasonic piezoelectric sandwich transducers can be stopped by a periodic array of circular holes drilled along the main propagation direction (a phononic crystal). In this work, the performance of different transducer designs made with this procedure is tested using laser vibrometry, electric impedance tests and finite element models (FEM). It is shown that in terms of mechanical vibration amplitude and acoustic efficiency, the best design for physiotherapy applications is when both, the piezoceramic and an aluminum capsule are phononic structures. The procedure described here can be applied to the design of power ultrasonic devices, physiotherapy transducers and other external medical power ultrasound applications where piston-like vibration in a narrow band is required. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2017)

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23 pages, 12155 KiB

Open AccessArticle

Investigation of a Combined Surveying and Scanning Device: The Trimble SX10 Scanning Total Station

by Elise Lachat^*, Tania Landes and Pierre Grussenmeyer

ICube Laboratory, Photogrammetry and Geomatics Group, National Institute of Applied Sciences (INSA), 24 Boulevard de la Victoire, 67084 Strasbourg CEDEX, France

Sensors 2017, 17(4), 730; https://doi.org/10.3390/s17040730 - 31 Mar 2017

Cited by 34 | Viewed by 9629

Abstract

Surveying fields from geosciences to infrastructure monitoring make use of a wide range of instruments for accurate 3D geometry acquisition. In many cases, the Terrestrial Laser Scanner (TLS) tends to become an optimal alternative to total station measurements thanks to the high point [...] Read more.

Surveying fields from geosciences to infrastructure monitoring make use of a wide range of instruments for accurate 3D geometry acquisition. In many cases, the Terrestrial Laser Scanner (TLS) tends to become an optimal alternative to total station measurements thanks to the high point acquisition rate it offers, but also to ever deeper data processing software functionalities. Nevertheless, traditional surveying techniques are valuable in some kinds of projects. Nowadays, a few modern total stations combine their conventional capabilities with those of a laser scanner in a unique device. The recent Trimble SX10 scanning total station is a survey instrument merging high-speed 3D scanning and the capabilities of an image-assisted total station. In this paper this new instrument is introduced and first compared to state-of-the-art image-assisted total stations. The paper also addresses the topic of various laser scanning projects and the delivered point clouds are compared with those of other TLS. Directly and indirectly georeferenced projects have been carried out and are investigated in this paper, and a polygonal traverse is performed through a building. Comparisons with the results delivered by well-established survey instruments show the reliability of the Trimble SX10 for geodetic work as well as for scanning projects. Full article

(This article belongs to the Section Remote Sensors)

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31 pages, 9132 KiB

Open AccessArticle

Monitoring and Discovery for Self-Organized Network Management in Virtualized and Software Defined Networks

by Ángel Leonardo Valdivieso Caraguay

and Luis Javier García Villalba^*

Group of Analysis, Security and Systems (GASS), Department of Software Engineering and Artificial Intelligence (DISIA), Faculty of Information Technology and Computer Science, Oﬃce 431, Universidad Complutense de Madrid (UCM), Calle Profesor José García Santesmases, 9, Ciudad Universitaria, 28040 Madrid, Spain

Sensors 2017, 17(4), 731; https://doi.org/10.3390/s17040731 - 31 Mar 2017

Cited by 15 | Viewed by 8712

Abstract

This paper presents the Monitoring and Discovery Framework of the Self-Organized Network Management in Virtualized and Software Defined Networks SELFNET project. This design takes into account the scalability and flexibility requirements needed by 5G infrastructures. In this context, the present framework focuses on [...] Read more.

This paper presents the Monitoring and Discovery Framework of the Self-Organized Network Management in Virtualized and Software Defined Networks SELFNET project. This design takes into account the scalability and flexibility requirements needed by 5G infrastructures. In this context, the present framework focuses on gathering and storing the information (low-level metrics) related to physical and virtual devices, cloud environments, flow metrics, SDN traffic and sensors. Similarly, it provides the monitoring data as a generic information source in order to allow the correlation and aggregation tasks. Our design enables the collection and storing of information provided by all the underlying SELFNET sublayers, including the dynamically onboarded and instantiated SDN/NFV Apps, also known as SELFNET sensors. Full article

(This article belongs to the Special Issue Advances on Resources Management for Multi-Platform Infrastructures)

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13 pages, 3014 KiB

Open AccessArticle

Bench-Top Fabrication of an All-PDMS Microfluidic Electrochemical Cell Sensor Integrating Micro/Nanostructured Electrodes

by Sokunthearath Saem, Yujie Zhu, Helen Luu and Jose Moran-Mirabal^*

Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4M1, Canada

Sensors 2017, 17(4), 732; https://doi.org/10.3390/s17040732 - 31 Mar 2017

Cited by 30 | Viewed by 9003

Abstract

In recent years, efforts in the development of lab-on-a-chip (LoC) devices for point-of-care (PoC) applications have increased to bring affordable, portable, and sensitive diagnostics to the patients’ bedside. To reach this goal, research has shifted from using traditional microfabrication methods to more versatile, [...] Read more.

In recent years, efforts in the development of lab-on-a-chip (LoC) devices for point-of-care (PoC) applications have increased to bring affordable, portable, and sensitive diagnostics to the patients’ bedside. To reach this goal, research has shifted from using traditional microfabrication methods to more versatile, rapid, and low-cost options. This work focuses on the benchtop fabrication of a highly sensitive, fully transparent, and flexible poly (dimethylsiloxane) (PDMS) microfluidic (μF) electrochemical cell sensor. The μF device encapsulates 3D structured gold and platinum electrodes, fabricated using a shape-memory polymer shrinking method, which are used to set up an on-chip electrochemical cell. The PDMS to PDMS-structured electrode bonding protocol to fabricate the μF chip was optimized and found to have sufficient bond strength to withstand up to 100 mL/min flow rates. The sensing capabilities of the on-chip electrochemical cell were demonstrated by using cyclic voltammetry to monitor the adhesion of murine 3T3 fibroblasts in the presence of a redox reporter. The charge transfer across the working electrode was reduced upon cell adhesion, which was used as the detection mechanism, and allowed the detection of as few as 24 cells. The effective utilization of simple and low cost bench-top fabrication methods could accelerate the prototyping and development of LoC technologies and bring PoC diagnostics and personalized medicine to the patients’ bedside. Full article

(This article belongs to the Special Issue Microfluidics-Based Microsystem Integration Research)

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16 pages, 1380 KiB

Open AccessArticle

Patients’ Data Management System Protected by Identity-Based Authentication and Key Exchange

by Alexandra Rivero-García¹

, Iván Santos-González¹, Candelaria Hernández-Goya¹, Pino Caballero-Gil^1,*

and Moti Yung²

¹ Department of Computer Engineering and Systems, University of La Laguna, 38206 Tenerife, Spain

² Computer Science Department, Snapchat and Columbia University, New York, NY 10027, USA

Sensors 2017, 17(4), 733; https://doi.org/10.3390/s17040733 - 31 Mar 2017

Cited by 6 | Viewed by 5853

Abstract

A secure and distributed framework for the management of patients’ information in emergency and hospitalization services is proposed here in order to seek improvements in efficiency and security in this important area. In particular, confidentiality protection, mutual authentication, and automatic identification of patients [...] Read more.

A secure and distributed framework for the management of patients’ information in emergency and hospitalization services is proposed here in order to seek improvements in efficiency and security in this important area. In particular, confidentiality protection, mutual authentication, and automatic identification of patients are provided. The proposed system is based on two types of devices: Near Field Communication (NFC) wristbands assigned to patients, and mobile devices assigned to medical staff. Two other main elements of the system are an intermediate server to manage the involved data, and a second server with a private key generator to define the information required to protect communications. An identity-based authentication and key exchange scheme is essential to provide confidential communication and mutual authentication between the medical staff and the private key generator through an intermediate server. The identification of patients is carried out through a keyed-hash message authentication code. Thanks to the combination of the aforementioned tools, a secure alternative mobile health (mHealth) scheme for managing patients’ data is defined for emergency and hospitalization services. Different parts of the proposed system have been implemented, including mobile application, intermediate server, private key generator and communication channels. Apart from that, several simulations have been performed, and, compared with the current system, significant improvements in efficiency have been observed. Full article

(This article belongs to the Special Issue Selected Papers from UCAmI 2016)

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13 pages, 10350 KiB

Open AccessArticle

Real-Time and High-Resolution 3D Face Measurement via a Smart Active Optical Sensor

by Yong You, Yang Shen^*, Guocai Zhang and Xiuwen Xing

School of Applied Science and Civil Engineering, Beijing Institute of Technology, Zhuhai 519088, China

Sensors 2017, 17(4), 734; https://doi.org/10.3390/s17040734 - 31 Mar 2017

Cited by 14 | Viewed by 4950

Abstract

The 3D measuring range and accuracy in traditional active optical sensing, such as Fourier transform profilometry, are influenced by the zero frequency of the captured patterns. The phase-shifting technique is commonly applied to remove the zero component. However, this phase-shifting method must capture [...] Read more.

The 3D measuring range and accuracy in traditional active optical sensing, such as Fourier transform profilometry, are influenced by the zero frequency of the captured patterns. The phase-shifting technique is commonly applied to remove the zero component. However, this phase-shifting method must capture several fringe patterns with phase difference, thereby influencing the real-time performance. This study introduces a smart active optical sensor, in which a composite pattern is utilized. The composite pattern efficiently combines several phase-shifting fringes and carrier frequencies. The method can remove zero frequency by using only one pattern. Model face reconstruction and human face measurement were employed to study the validity and feasibility of this method. Results show no distinct decrease in the precision of the novel method unlike the traditional phase-shifting method. The texture mapping technique was utilized to reconstruct a nature-appearance 3D digital face. Full article

(This article belongs to the Section Physical Sensors)

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29 pages, 2615 KiB

Open AccessArticle

Tracking a Non-Cooperative Target Using Real-Time Stereovision-Based Control: An Experimental Study

by Tomer Shtark and Pini Gurfil^*

Department of Aerospace Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel

Sensors 2017, 17(4), 735; https://doi.org/10.3390/s17040735 - 31 Mar 2017

Cited by 19 | Viewed by 6439

Abstract

Tracking a non-cooperative target is a challenge, because in unfamiliar environments most targets are unknown and unspecified. Stereovision is suited to deal with this issue, because it allows to passively scan large areas and estimate the relative position, velocity and shape of objects. [...] Read more.

Tracking a non-cooperative target is a challenge, because in unfamiliar environments most targets are unknown and unspecified. Stereovision is suited to deal with this issue, because it allows to passively scan large areas and estimate the relative position, velocity and shape of objects. This research is an experimental effort aimed at developing, implementing and evaluating a real-time non-cooperative target tracking methods using stereovision measurements only. A computer-vision feature detection and matching algorithm was developed in order to identify and locate the target in the captured images. Three different filters were designed for estimating the relative position and velocity, and their performance was compared. A line-of-sight control algorithm was used for the purpose of keeping the target within the field-of-view. Extensive analytical and numerical investigations were conducted on the multi-view stereo projection equations and their solutions, which were used to initialize the different filters. This research shows, using an experimental and numerical evaluation, the benefits of using the unscented Kalman filter and the total least squares technique in the stereovision-based tracking problem. These findings offer a general and more accurate method for solving the static and dynamic stereovision triangulation problems and the concomitant line-of-sight control. Full article

(This article belongs to the Special Issue Video Analysis and Tracking Using State-of-the-Art Sensors)

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22 pages, 4675 KiB

Open AccessArticle

The Additional Secondary Phase Correction System for AIS Signals

by Xiaoye Wang^*

, Shufang Zhang and Xiaowen Sun

Information Science and Technology College, Dalian Maritime University, Dalian 116026, China

Sensors 2017, 17(4), 736; https://doi.org/10.3390/s17040736 - 31 Mar 2017

Cited by 17 | Viewed by 4099

Abstract

This paper looks at the development and implementation of the additional secondary phase factor (ASF) real-time correction system for the Automatic Identification System (AIS) signal. A large number of test data were collected using the developed ASF correction system and the propagation characteristics [...] Read more.

This paper looks at the development and implementation of the additional secondary phase factor (ASF) real-time correction system for the Automatic Identification System (AIS) signal. A large number of test data were collected using the developed ASF correction system and the propagation characteristics of the AIS signal that transmits at sea and the ASF real-time correction algorithm of the AIS signal were analyzed and verified. Accounting for the different hardware of the receivers in the land-based positioning system and the variation of the actual environmental factors, the ASF correction system corrects original measurements of positioning receivers in real time and provides corrected positioning accuracy within 10 m. Full article

(This article belongs to the Section Remote Sensors)

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17 pages, 11597 KiB

Open AccessArticle

Activity Learning as a Foundation for Security Monitoring in Smart Homes

by Jessamyn Dahmen¹, Brian L. Thomas¹, Diane J. Cook^1,*

and Xiaobo Wang²

¹ School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA 99164, USA

² FutureWei Technologies, Inc., Santa Clara, CA 95050, USA

Sensors 2017, 17(4), 737; https://doi.org/10.3390/s17040737 - 31 Mar 2017

Cited by 41 | Viewed by 7932

Abstract

Smart environment technology has matured to the point where it is regularly used in everyday homes as well as research labs. With this maturation of the technology, we can consider using smart homes as a practical mechanism for improving home security. In this [...] Read more.

Smart environment technology has matured to the point where it is regularly used in everyday homes as well as research labs. With this maturation of the technology, we can consider using smart homes as a practical mechanism for improving home security. In this paper, we introduce an activity-aware approach to security monitoring and threat detection in smart homes. We describe our approach using the CASAS smart home framework and activity learning algorithms. By monitoring for activity-based anomalies we can detect possible threats and take appropriate action. We evaluate our proposed method using data collected in CASAS smart homes and demonstrate the partnership between activity-aware smart homes and biometric devices in the context of the CASAS on-campus smart apartment testbed. Full article

(This article belongs to the Special Issue Sensors for Home Automation and Security)

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12 pages, 3691 KiB

Open AccessArticle

Distributed Humidity Sensing in PMMA Optical Fibers at 500 nm and 650 nm Wavelengths

by Sascha Liehr^*

, Mathias Breithaupt and Katerina Krebber

Bundesanstalt für Materialforschung und–prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany

Sensors 2017, 17(4), 738; https://doi.org/10.3390/s17040738 - 31 Mar 2017

Cited by 32 | Viewed by 6394

Abstract

Distributed measurement of humidity is a sought-after capability for various fields of application, especially in the civil engineering and structural health monitoring sectors. This article presents a method for distributed humidity sensing along polymethyl methacrylate (PMMA) polymer optical fibers (POFs) by analyzing wavelength-dependent [...] Read more.

Distributed measurement of humidity is a sought-after capability for various fields of application, especially in the civil engineering and structural health monitoring sectors. This article presents a method for distributed humidity sensing along polymethyl methacrylate (PMMA) polymer optical fibers (POFs) by analyzing wavelength-dependent Rayleigh backscattering and attenuation characteristics at 500 nm and 650 nm wavelengths. Spatially resolved humidity sensing is obtained from backscatter traces of a dual-wavelength optical time domain reflectometer (OTDR). Backscatter dependence, attenuation dependence as well as the fiber length change are characterized as functions of relative humidity. Cross-sensitivity effects are discussed and quantified. The evaluation of the humidity-dependent backscatter effects at the two wavelength measurements allows for distributed and unambiguous measurement of relative humidity. The technique can be readily employed with low-cost standard polymer optical fibers and commercial OTDR devices. Full article

(This article belongs to the Special Issue Humidity Sensors)

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17 pages, 3130 KiB

Open AccessArticle

Object Tracking Using Local Multiple Features and a Posterior Probability Measure

by Wenhua Guo^*, Zuren Feng and Xiaodong Ren

Systems Engineering Institute, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(4), 739; https://doi.org/10.3390/s17040739 - 31 Mar 2017

Cited by 8 | Viewed by 5048

Abstract

Object tracking has remained a challenging problem in recent years. Most of the trackers can not work well, especially when dealing with problems such as similarly colored backgrounds, object occlusions, low illumination, or sudden illumination changes in real scenes. A centroid iteration algorithm [...] Read more.

Object tracking has remained a challenging problem in recent years. Most of the trackers can not work well, especially when dealing with problems such as similarly colored backgrounds, object occlusions, low illumination, or sudden illumination changes in real scenes. A centroid iteration algorithm using multiple features and a posterior probability criterion is presented to solve these problems. The model representation of the object and the similarity measure are two key factors that greatly influence the performance of the tracker. Firstly, this paper propose using a local texture feature which is a generalization of the local binary pattern (LBP) descriptor, which we call the double center-symmetric local binary pattern (DCS-LBP). This feature shows great discrimination between similar regions and high robustness to noise. By analyzing DCS-LBP patterns, a simplified DCS-LBP is used to improve the object texture model called the SDCS-LBP. The SDCS-LBP is able to describe the primitive structural information of the local image such as edges and corners. Then, the SDCS-LBP and the color are combined to generate the multiple features as the target model. Secondly, a posterior probability measure is introduced to reduce the rate of matching mistakes. Three strategies of target model update are employed. Experimental results show that our proposed algorithm is effective in improving tracking performance in complicated real scenarios compared with some state-of-the-art methods. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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10 pages, 1961 KiB

Open AccessArticle

Acousto-Optic–Based Wavelength-Comb-Swept Laser for Extended Displacement Measurements

by Nam Su Park^1,3, Soo Kyung Chun², Ga-Hee Han² and Chang-Seok Kim^1,2,*

¹ Department of Advanced Circuit Interconnection, Pusan National University, Busan 46241, Korea

² Department of Cogno-Mechanics Engineering, Pusan National University, Busan 46241, Korea

³ Advanced Circuit Interconnection Division, Samsung Electro-Mechanics, Busan 46754, Korea

Sensors 2017, 17(4), 740; https://doi.org/10.3390/s17040740 - 31 Mar 2017

Cited by 12 | Viewed by 5963

Abstract

We demonstrate a novel wavelength-comb-swept laser based on two intra-cavity filters: an acousto-optic tunable filter (AOTF) and a Fabry-Pérot etalon filter. The AOTF is used for the tunable selection of the output wavelength with time and the etalon filter for the narrowing of [...] Read more.

We demonstrate a novel wavelength-comb-swept laser based on two intra-cavity filters: an acousto-optic tunable filter (AOTF) and a Fabry-Pérot etalon filter. The AOTF is used for the tunable selection of the output wavelength with time and the etalon filter for the narrowing of the spectral linewidth to extend the coherence length. Compared to the conventional wavelength-swept laser, the acousto-optic–based wavelength-comb-swept laser (WCSL) can extend the measureable range of displacement measurements by decreasing the sensitivity roll-off of the point spread function. Because the AOTF contains no mechanical moving parts to select the output wavelength acousto-optically, the WCSL source has a high wavenumber (k) linearity of R² = 0.9999 to ensure equally spaced wavelength combs in the wavenumber domain. Full article

(This article belongs to the Special Issue Laser Sensors for Displacement, Distance, Flow, Velocity and Vibrations Measurements)

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13 pages, 804 KiB

Open AccessArticle

Strong Tracking Spherical Simplex-Radial Cubature Kalman Filter for Maneuvering Target Tracking

by Hua Liu

and Wen Wu^*

Ministerial Key Laboratory of JGMT, Nanjing University of Science and Technology, Nanjing 210094, China

Sensors 2017, 17(4), 741; https://doi.org/10.3390/s17040741 - 31 Mar 2017

Cited by 38 | Viewed by 5231

Abstract

Conventional spherical simplex-radial cubature Kalman filter (SSRCKF) for maneuvering target tracking may decline in accuracy and even diverge when a target makes abrupt state changes. To overcome this problem, a novel algorithm named strong tracking spherical simplex-radial cubature Kalman filter (STSSRCKF) is proposed [...] Read more.

Conventional spherical simplex-radial cubature Kalman filter (SSRCKF) for maneuvering target tracking may decline in accuracy and even diverge when a target makes abrupt state changes. To overcome this problem, a novel algorithm named strong tracking spherical simplex-radial cubature Kalman filter (STSSRCKF) is proposed in this paper. The proposed algorithm uses the spherical simplex-radial (SSR) rule to obtain a higher accuracy than cubature Kalman filter (CKF) algorithm. Meanwhile, by introducing strong tracking filter (STF) into SSRCKF and modifying the predicted states’ error covariance with a time-varying fading factor, the gain matrix is adjusted on line so that the robustness of the filter and the capability of dealing with uncertainty factors is improved. In this way, the proposed algorithm has the advantages of both STF’s strong robustness and SSRCKF’s high accuracy. Finally, a maneuvering target tracking problem with abrupt state changes is used to test the performance of the proposed filter. Simulation results show that the STSSRCKF algorithm can get better estimation accuracy and greater robustness for maneuvering target tracking. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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23 pages, 689 KiB

Open AccessArticle

Energy-Efficient Deadline-Aware Data-Gathering Scheme Using Multiple Mobile Data Collectors

by Rumpa Dasgupta and Seokhoon Yoon^*

Department of Electrical and Computer Engineering, University of Ulsan, Ulsan 680-749, Korea

Sensors 2017, 17(4), 742; https://doi.org/10.3390/s17040742 - 1 Apr 2017

Cited by 23 | Viewed by 4207

Abstract

In wireless sensor networks, the data collected by sensors are usually forwarded to the sink through multi-hop forwarding. However, multi-hop forwarding can be inefficient due to the energy hole problem and high communications overhead. Moreover, when the monitored area is large and the [...] Read more.

In wireless sensor networks, the data collected by sensors are usually forwarded to the sink through multi-hop forwarding. However, multi-hop forwarding can be inefficient due to the energy hole problem and high communications overhead. Moreover, when the monitored area is large and the number of sensors is small, sensors cannot send the data via multi-hop forwarding due to the lack of network connectivity. In order to address those problems of multi-hop forwarding, in this paper, we consider a data collection scheme that uses mobile data collectors (MDCs), which visit sensors and collect data from them. Due to the recent breakthroughs in wireless power transfer technology, MDCs can also be used to recharge the sensors to keep them from draining their energy. In MDC-based data-gathering schemes, a big challenge is how to find the MDCs’ traveling paths in a balanced way, such that their energy consumption is minimized and the packet-delay constraint is satisfied. Therefore, in this paper, we aim at finding the MDCs’ paths, taking energy efficiency and delay constraints into account. We first define an optimization problem, named the delay-constrained energy minimization (DCEM) problem, to find the paths for MDCs. An integer linear programming problem is formulated to find the optimal solution. We also propose a two-phase path-selection algorithm to efficiently solve the DCEM problem. Simulations are performed to compare the performance of the proposed algorithms with two heuristics algorithms for the vehicle routing problem under various scenarios. The simulation results show that the proposed algorithms can outperform existing algorithms in terms of energy efficiency and packet delay. Full article

(This article belongs to the Section Sensor Networks)

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13 pages, 2831 KiB

Open AccessArticle

Detection, Localization and Quantification of Impact Events on a Stiffened Composite Panel with Embedded Fiber Bragg Grating Sensor Networks

by Alfredo Lamberti^1,*, Geert Luyckx¹, Wim Van Paepegem¹, Ali Rezayat² and Steve Vanlanduit³

¹ Department of Materials, Textiles and Chemical Engineering (MaTCh), Ghent University, Technologiepark 903, 9052 Zwijnaarde, Belgium

² Department of Mechanical Engineering, Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Elsene, Belgium

³ Faculty of Applied Engineering, University of Antwerp, Campus Hoboken Salesianenlaan 90, 2660 Antwerp, Belgium

Sensors 2017, 17(4), 743; https://doi.org/10.3390/s17040743 - 1 Apr 2017

Cited by 23 | Viewed by 6118

Abstract

Nowadays, it is possible to manufacture smart composite materials with embedded fiber optic sensors. These sensors can be exploited during the composites’ operating life to identify occurring damages such as delaminations. For composite materials adopted in the aviation and wind energy sector, delaminations [...] Read more.

Nowadays, it is possible to manufacture smart composite materials with embedded fiber optic sensors. These sensors can be exploited during the composites’ operating life to identify occurring damages such as delaminations. For composite materials adopted in the aviation and wind energy sector, delaminations are most often caused by impacts with external objects. The detection, localization and quantification of such impacts are therefore crucial for the prevention of catastrophic events. In this paper, we demonstrate the feasibility to perform impact identification in smart composite structures with embedded fiber optic sensors. For our analyses, we manufactured a carbon fiber reinforced plate in which we embedded a distributed network of fiber Bragg grating (FBG) sensors. We impacted the plate with a modal hammer and we identified the impacts by processing the FBG data with an improved fast phase correlation (FPC) algorithm in combination with a variable selective least squares (VS-LS) inverse solver approach. A total of 164 impacts distributed on 41 possible impact locations were analyzed. We compared our methodology with the traditional P-Inv based approach. In terms of impact localization, our methodology performed better in 70.7% of the cases. An improvement on the impact time domain reconstruction was achieved in

95.1 %

of the cases. Full article

(This article belongs to the Section Physical Sensors)

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22 pages, 6080 KiB

Open AccessArticle

Downscaling Land Surface Temperature in Complex Regions by Using Multiple Scale Factors with Adaptive Thresholds

by Yingbao Yang¹, Xiaolong Li¹, Xin Pan^1,*, Yong Zhang² and Chen Cao¹

¹ School of Earth Science and Engineering, Hohai University, 8 Buddha City West Road, Nanjing 210098, China

² College of Natural Resources and Environment, Chizhou University, No.199 Muzhi Road, Chizhou 247000, China

Sensors 2017, 17(4), 744; https://doi.org/10.3390/s17040744 - 1 Apr 2017

Cited by 39 | Viewed by 5571

Abstract

Many downscaling algorithms have been proposed to address the issue of coarse-resolution land surface temperature (LST) derived from available satellite-borne sensors. However, few studies have focused on improving LST downscaling in urban areas with several mixed surface types. In this study, LST was [...] Read more.

Many downscaling algorithms have been proposed to address the issue of coarse-resolution land surface temperature (LST) derived from available satellite-borne sensors. However, few studies have focused on improving LST downscaling in urban areas with several mixed surface types. In this study, LST was downscaled by a multiple linear regression model between LST and multiple scale factors in mixed areas with three or four surface types. The correlation coefficients (CCs) between LST and the scale factors were used to assess the importance of the scale factors within a moving window. CC thresholds determined which factors participated in the fitting of the regression equation. The proposed downscaling approach, which involves an adaptive selection of the scale factors, was evaluated using the LST derived from four Landsat 8 thermal imageries of Nanjing City in different seasons. Results of the visual and quantitative analyses show that the proposed approach achieves relatively satisfactory downscaling results on 11 August, with coefficient of determination and root-mean-square error of 0.87 and 1.13 °C, respectively. Relative to other approaches, our approach shows the similar accuracy and the availability in all seasons. The best (worst) availability occurred in the region of vegetation (water). Thus, the approach is an efficient and reliable LST downscaling method. Future tasks include reliable LST downscaling in challenging regions and the application of our model in middle and low spatial resolutions. Full article

(This article belongs to the Special Issue Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment)

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18 pages, 2792 KiB

Open AccessArticle

Automotive System for Remote Surface Classification

by Aleksandr Bystrov^1,*

, Edward Hoare¹, Thuy-Yung Tran², Nigel Clarke², Marina Gashinova¹ and Mikhail Cherniakov¹

¹ School of Engineering, University of Birmingham, Birmingham B15 2TT, UK

² Jaguar Land Rover Research Department, Coventry CV3 4LF, UK

Sensors 2017, 17(4), 745; https://doi.org/10.3390/s17040745 - 1 Apr 2017

Cited by 29 | Viewed by 5401

Abstract

In this paper we shall discuss a novel approach to road surface recognition, based on the analysis of backscattered microwave and ultrasonic signals. The novelty of our method is sonar and polarimetric radar data fusion, extraction of features for separate swathes of illuminated [...] Read more.

In this paper we shall discuss a novel approach to road surface recognition, based on the analysis of backscattered microwave and ultrasonic signals. The novelty of our method is sonar and polarimetric radar data fusion, extraction of features for separate swathes of illuminated surface (segmentation), and using of multi-stage artificial neural network for surface classification. The developed system consists of 24 GHz radar and 40 kHz ultrasonic sensor. The features are extracted from backscattered signals and then the procedures of principal component analysis and supervised classification are applied to feature data. The special attention is paid to multi-stage artificial neural network which allows an overall increase in classification accuracy. The proposed technique was tested for recognition of a large number of real surfaces in different weather conditions with the average accuracy of correct classification of 95%. The obtained results thereby demonstrate that the use of proposed system architecture and statistical methods allow for reliable discrimination of various road surfaces in real conditions. Full article

(This article belongs to the Section Remote Sensors)

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12 pages, 5468 KiB

Open AccessArticle

Quantification of Lycopene, β-Carotene, and Total Soluble Solids in Intact Red-Flesh Watermelon (Citrullus lanatus) Using On-Line Near-Infrared Spectroscopy

by Elena Tamburini^*

, Stefania Costa

, Irene Rugiero, Paola Pedrini and Maria Gabriella Marchetti

Department of Life Science and Biotechnology, University of Ferrara, Via L. Borsari 46, Ferrara 44121, Italy

Sensors 2017, 17(4), 746; https://doi.org/10.3390/s17040746 - 11 Apr 2017

Cited by 48 | Viewed by 8463

Abstract

A great interest has recently been focused on lycopene and β-carotene, because of their antioxidant action in the organism. Red-flesh watermelon is one of the main sources of lycopene as the most abundant carotenoid. The use of near-infrared spectroscopy (NIRS) in post-harvesting has [...] Read more.

A great interest has recently been focused on lycopene and β-carotene, because of their antioxidant action in the organism. Red-flesh watermelon is one of the main sources of lycopene as the most abundant carotenoid. The use of near-infrared spectroscopy (NIRS) in post-harvesting has permitted us to rapidly quantify lycopene, β-carotene, and total soluble solids (TSS) on single intact fruits. Watermelons, harvested in 2013–2015, were submitted to near-infrared (NIR) radiation while being transported along a conveyor belt system, stationary and in movement, and at different positions on the belt. Eight hundred spectra from 100 samples were collected as calibration set in the 900–1700 nm interval. Calibration models were performed using partial least squares (PLS) regression on pre-treated spectra (derivatives and SNV) in the ranges 2.65–151.75 mg/kg (lycopene), 0.19–9.39 mg/kg (β-carotene), and 5.3%–13.7% (TSS). External validation was carried out with 35 new samples and on 35 spectra. The PLS models for intact watermelon could predict lycopene with R² = 0.877 and SECV = 15.68 mg/kg, β-carotene with R² = 0.822 and SECV = 0.81 mg/kg, and TSS with R² = 0.836 and SECV = 0.8%. External validation has confirmed predictive ability with R² = 0.805 and RMSEP = 16.19 mg/kg for lycopene, R2 = 0.737 and RMSEP = 0.96 mg/kg for β-carotene, and R² = 0.707 and RMSEP = 1.4% for TSS. The results allow for the market valorization of fruits. Full article

(This article belongs to the Section Chemical Sensors)

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9 pages, 3827 KiB

Open AccessArticle

Conductive Photo-Activated Porphyrin-ZnO Nanostructured Gas Sensor Array

by Gabriele Magna¹

, Alexandro Catini¹

, Raj Kumar¹, Massimo Palmacci¹, Eugenio Martinelli¹, Roberto Paolesse² and Corrado Di Natale^1,*

¹ Department of Electronic Engineering, University of Rome Tor Vergata, Via Politecnico 1, 00133 Roma, Italy

² Department of Chemical Science and Technology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Roma, Italy

Sensors 2017, 17(4), 747; https://doi.org/10.3390/s17040747 - 1 Apr 2017

Cited by 19 | Viewed by 5684

Abstract

Chemoresistors working at room temperature are attractive for low-consumption integrated sensors. Previous studies show that this feature can be obtained with photoconductive porphyrins-coated ZnO nanostructures. Furthermore, variations of the porphyrin molecular structure alter both the chemical sensitivity and the photoconductivity, and can be [...] Read more.

Chemoresistors working at room temperature are attractive for low-consumption integrated sensors. Previous studies show that this feature can be obtained with photoconductive porphyrins-coated ZnO nanostructures. Furthermore, variations of the porphyrin molecular structure alter both the chemical sensitivity and the photoconductivity, and can be used to define the sensor characteristics. Based on these assumptions, we investigated the properties of an array of four sensors made of a layer of ZnO nanoparticles coated with porphyrins with the same molecular framework but different metal atoms. The array was tested with five volatile organic compounds (VOCs), each measured at different concentrations. Results confirm that the features of individual porphyrins influence the sensor behavior, and the differences among sensors are enough to enable the discrimination of volatile compounds disregarding their concentration. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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12 pages, 2086 KiB

Open AccessArticle

Fiber Bragg Grating Measuring System for Simultaneous Monitoring of Temperature and Humidity in Mechanical Ventilation

by Carlo Massaroni¹, Michele A. Caponero²

, Rosaria D’Amato²

, Daniela Lo Presti¹ and Emiliano Schena^1,*

¹ Unit of Measurements and Biomedical Instrumentation, Center for Integrated Research, Università Campus Bio-Medico di Roma, Via Álvaro del Portillo, 21, 00128 Rome, Italy

² Photonics Micro- and Nanostructures Laboratory Research Centre of Frascati, ENEA, Via Enrico Fermi, 45, Frascati, 00044 Rome, Italy

Sensors 2017, 17(4), 749; https://doi.org/10.3390/s17040749 - 2 Apr 2017

Cited by 65 | Viewed by 8091

Abstract

During mechanical ventilation, the humidification of the dry air delivered by the mechanical ventilator is recommended. Among several solutions, heated wire humidifiers (HWHs) have gained large acceptance to be used in this field. The aim of this work is to fabricate a measuring [...] Read more.

During mechanical ventilation, the humidification of the dry air delivered by the mechanical ventilator is recommended. Among several solutions, heated wire humidifiers (HWHs) have gained large acceptance to be used in this field. The aim of this work is to fabricate a measuring system based on fiber Bragg grating (FBG) for the simultaneous monitoring of gas relative humidity (RH) and temperature, intended to be used for providing feedback to the HWHs’ control. This solution can be implemented using an array of two FBGs having a different center wavelength. Regarding RH monitoring, three sensors have been fabricated by coating an FBG with two different moisture-sensitive and biocompatible materials: the first two sensors were fabricated by coating the grating with a 3 mm × 3 mm layer of agar and agarose; to investigate the influence of the coating thickness to the sensor response, a third sensor was developed with a 5 mm × 5 mm layer of agar. The sensors have been assessed in a wide range of RH (up to 95%) during both an ascending and a subsequent descending phase. Only the response of the 3 mm × 3 mm-coated sensors were fast enough to follow the RH changes, showing a mean sensitivity of about 0.14 nm/% (agar-coated) and 0.12 nm/% (agarose-coated). The hysteresis error was about <10% in the two sensors. The contribution of temperature changes on these RH sensors was negligible. The temperature measurement was performed by a commercial FBG insensitive to RH changes. The small size of these FBG-based sensors, the use of biocompatible polymers, and the possibility to measure both temperature and RH by using the same fiber optic embedding an array of two FBGs make intriguing the use of this solution for application in the control of HWHs. Full article

(This article belongs to the Special Issue Humidity Sensors)

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12 pages, 7219 KiB

Open AccessArticle

Parallel Detection of Refractive Index Changes in a Porous Silicon Microarray Based on Digital Images

by Chuanxi Li¹, Zhenhong Jia^2,*, Peng Li¹, Hao Wen³, Guodong Lv³ and Xiaohui Huang²

¹ School of Physical Science and Technology, Xinjiang University, Urumqi 830046, China

² College of Information Science and Engineering, Xinjiang University, Urumqi 830046, China

³ The First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, China

Sensors 2017, 17(4), 750; https://doi.org/10.3390/s17040750 - 2 Apr 2017

Cited by 12 | Viewed by 4679

Abstract

A new technique for the refractive index change with high-sensitivity measurements was proposed by the digital image of porous silicon (PSi) microarray utilization in this paper. Under the irradiation of a He-Ne laser, the surface images of the PSi array cells with the [...] Read more.

A new technique for the refractive index change with high-sensitivity measurements was proposed by the digital image of porous silicon (PSi) microarray utilization in this paper. Under the irradiation of a He-Ne laser, the surface images of the PSi array cells with the microcavity structure were obtained by the digital imaging equipment, whereas the refractive index change of each array cells was detected by calculating the average gray value of the image and the refractive index change measurement sensitivity was 10⁻⁴. This technique could be utilized in the label-free and parallel detection of refraction index changes induced by a biological reaction in the microarray or the chip. Full article

(This article belongs to the Special Issue Silicon Technologies for Photonic Sensors)

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17 pages, 4686 KiB

Open AccessArticle

Comparison of Adaptive Spectral Estimation for Vehicle Speed Measurement with Radar Sensors

by Khairul Khaizi Mohd Shariff, Edward Hoare, Liam Daniel, Michail Antoniou and Mikhail Cherniakov^*

Microwave Integrated Systems Laboratory, University of Birmingham, Birmingham B15 2TT, UK

Sensors 2017, 17(4), 751; https://doi.org/10.3390/s17040751 - 2 Apr 2017

Cited by 17 | Viewed by 7716

Abstract

Vehicle speed-over-ground (SoG) radar offers significant advantages over conventional speed measurement systems. Radar sensors enable contactless speed measurement, which is free from wheel slip. One of the key issues in SoG radar is the development of the Doppler shift estimation algorithm. In this [...] Read more.

Vehicle speed-over-ground (SoG) radar offers significant advantages over conventional speed measurement systems. Radar sensors enable contactless speed measurement, which is free from wheel slip. One of the key issues in SoG radar is the development of the Doppler shift estimation algorithm. In this paper, we compared two algorithms to estimate a mean Doppler frequency accurately. The first is the center-of-mass algorithm, which based on spectrum center-of-mass estimation with a bandwidth-limiting technique. The second is the cross-correlation algorithm, which is based on a cross-correlation technique by cross-correlating Doppler spectrum with a theoretical Gaussian curve. Analysis shows that both algorithms are computationally efficient and suitable for real-time SoG systems. Our extensive simulated and experimental results show both methods achieved low estimation error between 0.5% and 1.5% for flat road conditions. In terms of reliability, the cross-correlation method shows good performance under low Signal-to-Noise Ratio (SNR) while the center-of-mass method failed in this condition. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in UK)

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17 pages, 3072 KiB

Open AccessArticle

Security Enhancement of Wireless Sensor Networks Using Signal Intervals

by Jaegeun Moon¹, Im Y. Jung^1,* and Jaesoo Yoo²

¹ School of Electronics Engineering, Kyungpook National University, 80 Daehakro Buk-gu, Daegu 702701, Korea

² School of Information and Communication Engineering, Chungbuk National University, 1 Chungdaero Seowon-gu, Cheongju 28644, Korea

Sensors 2017, 17(4), 752; https://doi.org/10.3390/s17040752 - 2 Apr 2017

Cited by 2 | Viewed by 4873

Abstract

Various wireless technologies, such as RF, Bluetooth, and Zigbee, have been applied to sensor communications. However, the applications of Bluetooth-based wireless sensor networks (WSN) have a security issue. In one pairing process during Bluetooth communication, which is known as simple secure pairing (SSP), [...] Read more.

Various wireless technologies, such as RF, Bluetooth, and Zigbee, have been applied to sensor communications. However, the applications of Bluetooth-based wireless sensor networks (WSN) have a security issue. In one pairing process during Bluetooth communication, which is known as simple secure pairing (SSP), the devices are required to specify I/O capability or user interference to prevent man-in-the-middle (MITM) attacks. This study proposes an enhanced SSP in which a nonce to be transferred is converted to a corresponding signal interval. The quantization level, which is used to interpret physical signal intervals, is renewed at every connection by the transferred nonce and applied to the next nonce exchange so that the same signal intervals can represent different numbers. Even if attackers eavesdrop on the signals, they cannot understand what is being transferred because they cannot determine the quantization level. Furthermore, the proposed model does not require exchanging passkeys as data, and the devices are secure in the case of using a fixed PIN. Subsequently, the new quantization level is calculated automatically whenever the same devices attempt to connect with each other. Therefore, the pairing process can be protected from MITM attacks and be convenient for users. Full article

(This article belongs to the Special Issue New Generation Sensors Enabling and Fostering IoT)

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8 pages, 898 KiB

Open AccessArticle

Strategy for Accurate Detection of Escherichia coli O157:H7 in Ground Pork Using a Lateral Flow Immunoassay

by Song Cheng¹, Ming-hui Chen¹, Gang-gang Zhang¹, Zhi-biao Yu², Dao-feng Liu¹, Yong-hua Xiong¹, Hua Wei¹ and Wei-hua Lai^1,*

¹ State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China

² Department of Science and Technology, Nanchang University, Nanchang 330047, China

Sensors 2017, 17(4), 753; https://doi.org/10.3390/s17040753 - 2 Apr 2017

Cited by 11 | Viewed by 5448

Abstract

Escherichia coli O157:H7 is known to cause serious diseases including hemorrhagic colitis and hemolytic uremic syndrome. A gold nanoparticle lateral flow immunoassay (Au-LFIA) was used to detect Escherichia coli O157:H7 in ground pork samples. False-positive results were detected using Au-LFIA; a Citrobacter freundii [...] Read more.

Escherichia coli O157:H7 is known to cause serious diseases including hemorrhagic colitis and hemolytic uremic syndrome. A gold nanoparticle lateral flow immunoassay (Au-LFIA) was used to detect Escherichia coli O157:H7 in ground pork samples. False-positive results were detected using Au-LFIA; a Citrobacter freundii strain was isolated from the ground pork samples and identified by using CHROmagar^TM plates, API 20E, and 16S RNA sequencing. Since C. freundii showed cross-reactivity with E. coli O157:H7 when Au-LFIA test strips were used, a novel method combining modified enrichment with a lateral flow immunoassay for accurate and convenient detection of E. coli O157:H7 in ground pork was developed in this study to minimize these false positives. MacConkey broth was optimized for E. coli O157:H7 enrichment and C. freundii inhibition by the addition of 5 mg/L potassium tellurite and 0.10 mg/L cefixime. Using the proposed modified enrichment procedure, the false-positive rate of ground pork samples spiked with 100 CFU/g C. freundii decreased to 5%. Full article

(This article belongs to the Special Issue Sensors for Toxic and Pathogen Detection)

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22 pages, 8703 KiB

Open AccessArticle

Electronic Noses for Composites Surface Contamination Detection in Aerospace Industry

by Saverio De Vito^*

, Maria Lucia Miglietta, Ettore Massera

, Grazia Fattoruso, Fabrizio Formisano, Tiziana Polichetti, Maria Salvato, Brigida Alfano, Elena Esposito and Girolamo Di Francia^*

ENEA—Italian National Agency for New Technologies, Energy and Sustainable Economic Development, PV and Smart Network Division, C.R. ENEA Portici, P.le E. Fermi, 1, 80055 Portici, Italy

Sensors 2017, 17(4), 754; https://doi.org/10.3390/s17040754 - 2 Apr 2017

Cited by 12 | Viewed by 5206

Abstract

The full exploitation of Composite Fiber Reinforced Polymers (CFRP) in so-called green aircrafts design is still limited by the lack of adequate quality assurance procedures for checking the adhesive bonding assembly, especially in load-critical primary structures. In this respect, contamination of the CFRP [...] Read more.

The full exploitation of Composite Fiber Reinforced Polymers (CFRP) in so-called green aircrafts design is still limited by the lack of adequate quality assurance procedures for checking the adhesive bonding assembly, especially in load-critical primary structures. In this respect, contamination of the CFRP panel surface is of significant concern since it may severely affect the bonding and the mechanical properties of the joint. During the last years, the authors have developed and tested an electronic nose as a non-destructive tool for pre-bonding surface inspection for contaminants detection, identification and quantification. Several sensors and sampling architectures have been screened in view of the high Technology Readiness Level (TRL) scenarios requirements. Ad-hoc pattern recognition systems have also been devised to ensure a fast and reliable assessment of the contamination status, by combining real time classifiers and the implementation of a suitable rejection option. Results show that e-noses could be used as first line low cost Non Destructive Test (NDT) tool in aerospace CFRP assembly and maintenance scenarios. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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19 pages, 6343 KiB

Open AccessFeature PaperArticle

The Combination of Micro Diaphragm Pumps and Flow Sensors for Single Stroke Based Liquid Flow Control

by Christoph Jenke^*, Jaume Pallejà Rubio, Sebastian Kibler, Johannes Häfner, Martin Richter and Christoph Kutter

Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT, 80686 Munich, Germany

Sensors 2017, 17(4), 755; https://doi.org/10.3390/s17040755 - 3 Apr 2017

Cited by 29 | Viewed by 8765

Abstract

With the combination of micropumps and flow sensors, highly accurate and secure closed-loop controlled micro dosing systems for liquids are possible. Implementing a single stroke based control mode with piezoelectrically driven micro diaphragm pumps can provide a solution for dosing of volumes down [...] Read more.

With the combination of micropumps and flow sensors, highly accurate and secure closed-loop controlled micro dosing systems for liquids are possible. Implementing a single stroke based control mode with piezoelectrically driven micro diaphragm pumps can provide a solution for dosing of volumes down to nanoliters or variable average flow rates in the range of nL/min to μL/min. However, sensor technologies feature a yet undetermined accuracy for measuring highly pulsatile micropump flow. Two miniaturizable in-line sensor types providing electrical readout—differential pressure based flow sensors and thermal calorimetric flow sensors—are evaluated for their suitability of combining them with mircopumps. Single stroke based calibration of the sensors was carried out with a new method, comparing displacement volumes and sensor flow volumes. Limitations of accuracy and performance for single stroke based flow control are described. Results showed that besides particle robustness of sensors, controlling resistive and capacitive damping are key aspects for setting up reproducible and reliable liquid dosing systems. Depending on the required average flow or defined volume, dosing systems with an accuracy of better than 5% for the differential pressure based sensor and better than 6.5% for the thermal calorimeter were achieved. Full article

(This article belongs to the Special Issue Microfluidic Sensors and Control Devices)

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13 pages, 2242 KiB

Open AccessArticle

The Impact of Estimating High-Resolution Tropospheric Gradients on Multi-GNSS Precise Positioning

by Feng Zhou^1,2,3, Xingxing Li³, Weiwei Li^4,*

, Wen Chen^1,2

, Danan Dong^1,2, Jens Wickert^3,5

and Harald Schuh^3,5

¹ Engineering Center of SHMEC for Space Information and GNSS, East China Normal University, No. 500 Dongchuan Road, Shanghai 200241, China

² Shanghai Key Laboratory of Multidimensional Information Processing, East China Normal University, No. 500 Dongchuan Road, Shanghai 200241, China

³ German Research Centre for Geosciences GFZ, Telegrafenberg, Potsdam 14473, Germany

⁴ College of Surveying and Geo-informatics, Tongji University, Shanghai 200092, China

⁵ Faculty VI Planning Building Environment, Technical University of Berlin, Berlin 10623, Germany

Sensors 2017, 17(4), 756; https://doi.org/10.3390/s17040756 - 3 Apr 2017

Cited by 19 | Viewed by 5309

Abstract

Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only [...] Read more.

Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only in positioning, navigation, and timing (PNT), but also in remote sensing of the atmosphere and ionosphere. Both precise positioning and the derivation of atmospheric parameters can benefit from multi-GNSS observations. In this contribution, extensive evaluations are conducted with multi-GNSS datasets collected from 134 globally-distributed ground stations of the International GNSS Service (IGS) Multi-GNSS Experiment (MGEX) network in July 2016. The datasets are processed in six different constellation combinations, i.e., GPS-, GLONASS-, BDS-only, GPS + GLONASS, GPS + BDS, and GPS + GLONASS + BDS + Galileo precise point positioning (PPP). Tropospheric gradients are estimated with eight different temporal resolutions, from 1 h to 24 h, to investigate the impact of estimating high-resolution gradients on position estimates. The standard deviation (STD) is used as an indicator of positioning repeatability. The results show that estimating tropospheric gradients with high temporal resolution can achieve better positioning performance than the traditional strategy in which tropospheric gradients are estimated on a daily basis. Moreover, the impact of estimating tropospheric gradients with different temporal resolutions at various elevation cutoff angles (from 3° to 20°) is investigated. It can be observed that with increasing elevation cutoff angles, the improvement in positioning repeatability is decreased. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 1825 KiB

Open AccessFeature PaperArticle

Non-Gaussian Resistance Fluctuations in Gold-Nanoparticle-Based Gas Sensors: An Appraisal of Different Evaluation Techniques

by Łukasz Lentka^1,*

, Janusz Smulko^1,*

, Mateusz Kotarski¹, Claes-Göran Granqvist² and Radu Ionescu³

¹ Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland

² Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, P.O. Box 534, SE-75121 Uppsala, Sweden

³ Rovira i Virgili University, ETSE-DEEEA, Department of Electronics, Carrer de l’Escorxador, 43003 Tarragona, Spain

Sensors 2017, 17(4), 757; https://doi.org/10.3390/s17040757 - 3 Apr 2017

Cited by 2 | Viewed by 4987

Abstract

Volatile organic compounds, such as formaldehyde, can be used as biomarkers in human exhaled breath in order to non-invasively detect various diseases, and the same compounds are of much interest also in the context of environmental monitoring and protection. Here, we report on [...] Read more.

Volatile organic compounds, such as formaldehyde, can be used as biomarkers in human exhaled breath in order to non-invasively detect various diseases, and the same compounds are of much interest also in the context of environmental monitoring and protection. Here, we report on a recently-developed gas sensor, based on surface-functionalized gold nanoparticles, which is able to generate voltage noise with a distinctly non-Gaussian component upon exposure to formaldehyde with concentrations on the ppm level, whereas this component is absent, or at least much weaker, when the sensor is exposed to ethanol or to pure air. We survey four different statistical methods to elucidate a non-Gaussian component and assess their pros and cons with regard to efficient gas detection. Specifically, the non-Gaussian component was clearly exposed in analysis using level-crossing parameters, which require nothing but a modest computational effort and simple electronic circuitry, and analogous results could be reached through the bispectrum function, albeit with more intense computation. Useful information could be obtained also via the Lévy-stable distribution and, possibly, the second spectrum. Full article

(This article belongs to the Collection Gas Sensors)

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12 pages, 6316 KiB

Open AccessArticle

Depth Edge Filtering Using Parameterized Structured Light Imaging

by Ziqi Zheng, Seho Bae and Juneho Yi^*

College of Information and Communication Engineering, Sungkyunkwan University, Suwon 16419, Korea

Sensors 2017, 17(4), 758; https://doi.org/10.3390/s17040758 - 3 Apr 2017

Cited by 2 | Viewed by 4288

Abstract

This research features parameterized depth edge detection using structured light imaging that exploits a single color stripes pattern and an associated binary stripes pattern. By parameterized depth edge detection, we refer to the detection of all depth edges in a given range of [...] Read more.

This research features parameterized depth edge detection using structured light imaging that exploits a single color stripes pattern and an associated binary stripes pattern. By parameterized depth edge detection, we refer to the detection of all depth edges in a given range of distances with depth difference greater or equal to a specific value. While previous research has not properly dealt with shadow regions, which result in double edges, we effectively remove shadow regions using statistical learning through effective identification of color stripes in the structured light images. We also provide a much simpler control of involved parameters. We have compared the depth edge filtering performance of our method with that of the state-of-the-art method and depth edge detection from the Kinect depth map. Experimental results clearly show that our method finds the desired depth edges most correctly while the other methods cannot. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 7306 KiB

Open AccessArticle

A Reconfigurable Readout Integrated Circuit for Heterogeneous Display-Based Multi-Sensor Systems

by Kyeonghwan Park

, Seung Mok Kim, Won-Jin Eom and Jae Joon Kim^*

School of Electrical and Computer Engineering, Ulsan National Institute of Science and Technology, 44919 Ulsan, Korea

Sensors 2017, 17(4), 759; https://doi.org/10.3390/s17040759 - 3 Apr 2017

Cited by 8 | Viewed by 8295

Abstract

This paper presents a reconfigurable multi-sensor interface and its readout integrated circuit (ROIC) for display-based multi-sensor systems, which builds up multi-sensor functions by utilizing touch screen panels. In addition to inherent touch detection, physiological and environmental sensor interfaces are incorporated. The reconfigurable feature [...] Read more.

This paper presents a reconfigurable multi-sensor interface and its readout integrated circuit (ROIC) for display-based multi-sensor systems, which builds up multi-sensor functions by utilizing touch screen panels. In addition to inherent touch detection, physiological and environmental sensor interfaces are incorporated. The reconfigurable feature is effectively implemented by proposing two basis readout topologies of amplifier-based and oscillator-based circuits. For noise-immune design against various noises from inherent human-touch operations, an alternate-sampling error-correction scheme is proposed and integrated inside the ROIC, achieving a 12-bit resolution of successive approximation register (SAR) of analog-to-digital conversion without additional calibrations. A ROIC prototype that includes the whole proposed functions and data converters was fabricated in a 0.18 μm complementary metal oxide semiconductor (CMOS) process, and its feasibility was experimentally verified to support multiple heterogeneous sensing functions of touch, electrocardiogram, body impedance, and environmental sensors. Full article

(This article belongs to the Section Physical Sensors)

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8 pages, 2003 KiB

Open AccessArticle

An Exonuclease I-Based Quencher-Free Fluorescent Method Using DNA Hairpin Probes for Rapid Detection of MicroRNA

by Changbei Ma^*, Haisheng Liu, Kefeng Wu, Mingjian Chen, Liyang Zheng and Jun Wang^*

State Key Laboratory of Medical Genetics & School of Life Sciences, Central South University, Changsha 410013, China

Sensors 2017, 17(4), 760; https://doi.org/10.3390/s17040760 - 3 Apr 2017

Cited by 17 | Viewed by 5614

Abstract

MicroRNAs (miRNAs) act as biomarkers for the diagnosis of a variety of cancers. Since the currently used methods for miRNA detection have limitations, simple, sensitive, and cost-effective methods for the detection of miRNA are required. This work demonstrates a facile, quencher-free, fluorescence-based analytical [...] Read more.

MicroRNAs (miRNAs) act as biomarkers for the diagnosis of a variety of cancers. Since the currently used methods for miRNA detection have limitations, simple, sensitive, and cost-effective methods for the detection of miRNA are required. This work demonstrates a facile, quencher-free, fluorescence-based analytical method for cost-effective and sensitive detection of miRNA using a super 2-aminopurine (2-AP)-labeled hairpin probe (HP) and exonuclease I activity. Specifically, the fluorescence of 2-AP is strongly quenched when it is incorporated within DNA. In the presence of a target miRNA, HP attains an open conformation by hybridizing with the target miRNA to form a double-stranded structure with a protruding 3′-terminus. Next, the digestion of the protruding 3′-terminus is triggered by exonuclease I, during which 2-AP is released free in solution from the DNA, thereby increasing fluorescence. This method is highly sensitive, with a detection limit of 0.5 nM—10 times lower than a previously reported quencher-free fluorescence method. Furthermore, this method has potential applications in clinical diagnosis and biomedical research. Full article

(This article belongs to the Special Issue Genosensing)

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12 pages, 3011 KiB

Open AccessArticle

Implications for a Wireless, External Device System to Study Electrocorticography

by David Rotermund^1,*

, Jonas Pistor², Janpeter Hoeffmann², Tim Schellenberg³, Dmitriy Boll⁴, Elena Tolstosheeva⁴, Dieter Gauck⁵, Heiko Stemmann⁵, Dagmar Peters-Drolshagen², Andreas Kurt Kreiter⁵, Martin Schneider³, Steffen Paul², Walter Lang⁴ and Klaus Richard Pawelzik¹

¹ Institute for Theoretical Physics, University of Bremen, 28359 Bremen, Germany

² Institute of Electrodynamics and Microelectronics, University of Bremen, 28359 Bremen, Germany

³ RF and Microwave Engineering Laboratory, University of Bremen, 28359 Bremen, Germany

⁴ Institute for Microsensors, -Actuators and -Systems, University of Bremen, 28359 Bremen, Germany

⁵ Institute for Brain Research, University of Bremen, 28359 Bremen, Germany

Sensors 2017, 17(4), 761; https://doi.org/10.3390/s17040761 - 4 Apr 2017

Cited by 3 | Viewed by 7134

Abstract

Implantable neuronal interfaces to the brain are an important keystone for future medical applications. However, entering this field of research is difficult since such an implant requires components from many different areas of technology. Since the complete avoidance of wires is important due [...] Read more.

Implantable neuronal interfaces to the brain are an important keystone for future medical applications. However, entering this field of research is difficult since such an implant requires components from many different areas of technology. Since the complete avoidance of wires is important due to the risk of infections and other long-term problems, means for wirelessly transmitting data and energy are a necessity which adds to the requirements. In recent literature, many high-tech components for such implants are presented with remarkable properties. However, these components are typically not freely available for such a system. Every group needs to re-develop their own solution. This raises the question if it is possible to create a reusable design for an implant and its external base-station, such that it allows other groups to use it as a starting point. In this article, we try to answer this question by presenting a design based exclusively on commercial off-the-shelf components and studying the properties of the resulting system. Following this idea, we present a fully wireless neuronal implant for simultaneously measuring electrocorticography signals at 128 locations from the surface of the brain. All design files are available as open source. Full article

(This article belongs to the Section Biosensors)

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15 pages, 882 KiB

Open AccessArticle

Underwater Robot Task Planning Using Multi-Objective Meta-Heuristics

by Itziar Landa-Torres¹, Diana Manjarres¹

, Sonia Bilbao¹ and Javier Del Ser^1,2,3,*

¹ TECNALIA, 48160 Derio, Bizkaia, Spain

² Department of Communications Engineering, University of the Basque Country (UPV/EHU), 48013 Bilbao, Bizkaia, Spain

³ Basque Center for Applied Mathematics, 48009 Bilbao, Bizkaia, Spain

Sensors 2017, 17(4), 762; https://doi.org/10.3390/s17040762 - 4 Apr 2017

Cited by 23 | Viewed by 5468

Abstract

Robotics deployed in the underwater medium are subject to stringent operational conditions that impose a high degree of criticality on the allocation of resources and the schedule of operations in mission planning. In this context the so-called cost of a mission must be [...] Read more.

Robotics deployed in the underwater medium are subject to stringent operational conditions that impose a high degree of criticality on the allocation of resources and the schedule of operations in mission planning. In this context the so-called cost of a mission must be considered as an additional criterion when designing optimal task schedules within the mission at hand. Such a cost can be conceived as the impact of the mission on the robotic resources themselves, which range from the consumption of battery to other negative effects such as mechanic erosion. This manuscript focuses on this issue by devising three heuristic solvers aimed at efficiently scheduling tasks in robotic swarms, which collaborate together to accomplish a mission, and by presenting experimental results obtained over realistic scenarios in the underwater environment. The heuristic techniques resort to a Random-Keys encoding strategy to represent the allocation of robots to tasks and the relative execution order of such tasks within the schedule of certain robots. The obtained results reveal interesting differences in terms of Pareto optimality and spread between the algorithms considered in the benchmark, which are insightful for the selection of a proper task scheduler in real underwater campaigns. Full article

(This article belongs to the Special Issue Sensing Technologies for Autonomy and Cooperation in Underwater Networked Robot Systems)

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15 pages, 3283 KiB

Open AccessArticle

Elimination of Harmonic Force and Torque in Active Magnetic Bearing Systems with Repetitive Control and Notch Filters

by Xiangbo Xu, Shao Chen^*

and Jinhao Liu

School of Technology, Beijing Forestry University, No. 35 Tsinghua East Road, Haidian District, Beijing 100083, China

Sensors 2017, 17(4), 763; https://doi.org/10.3390/s17040763 - 4 Apr 2017

Cited by 13 | Viewed by 5466

Abstract

Harmonic force and torque, which are caused by rotor imbalance and sensor runout, are the dominant disturbances in active magnetic bearing (AMB) systems. To eliminate the harmonic force and torque, a novel control method based on repetitive control and notch filters is proposed. [...] Read more.

Harmonic force and torque, which are caused by rotor imbalance and sensor runout, are the dominant disturbances in active magnetic bearing (AMB) systems. To eliminate the harmonic force and torque, a novel control method based on repetitive control and notch filters is proposed. Firstly, the dynamics of a four radial degrees of freedom AMB system is described, and the AMB model can be described in terms of the translational and rotational motions, respectively. Next, a closed-loop generalized notch filter is utilized to identify the synchronous displacement resulting from the rotor imbalance, and a feed-forward compensation of the synchronous force and torque related to the AMB displacement stiffness is formulated by using the identified synchronous displacement. Then, a plug-in repetitive controller is designed to track the synchronous feed-forward compensation adaptively and to suppress the harmonic vibrations due to the sensor runout. Finally, the proposed control method is verified by simulations and experiments. The control algorithm is insensitive to the parameter variations of the power amplifiers and can precisely suppress the harmonic force and torque. Its practicality stems from its low computational load. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 4091 KiB

Open AccessArticle

Power MOSFET Linearizer of a High-Voltage Power Amplifier for High-Frequency Pulse-Echo Instrumentation

by Hojong Choi¹, Park Chul Woo¹, Jung-Yeol Yeom^2,* and Changhan Yoon^3,*

¹ Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39253, Korea

² School of Biomedical Engineering, Korea University, Seoul 02841, Korea

³ Department of Biomedical Engineering, Inje University, Gimhae 50834, Korea

Sensors 2017, 17(4), 764; https://doi.org/10.3390/s17040764 - 4 Apr 2017

Cited by 33 | Viewed by 6477

Abstract

A power MOSFET linearizer is proposed for a high-voltage power amplifier (HVPA) used in high-frequency pulse-echo instrumentation. The power MOSFET linearizer is composed of a DC bias-controlled series power MOSFET shunt with parallel inductors and capacitors. The proposed scheme is designed to improve [...] Read more.

A power MOSFET linearizer is proposed for a high-voltage power amplifier (HVPA) used in high-frequency pulse-echo instrumentation. The power MOSFET linearizer is composed of a DC bias-controlled series power MOSFET shunt with parallel inductors and capacitors. The proposed scheme is designed to improve the gain deviation characteristics of the HVPA at higher input powers. By controlling the MOSFET bias voltage in the linearizer, the gain reduction into the HVPA was compensated, thereby reducing the echo harmonic distortion components generated by the ultrasonic transducers. In order to verify the performance improvement of the HVPA implementing the power MOSFET linearizer, we measured and found that the gain deviation of the power MOSFET linearizer integrated with HVPA under 10 V DC bias voltage was reduced (−1.8 and −0.96 dB, respectively) compared to that of the HVPA without the power MOSFET linearizer (−2.95 and −3.0 dB, respectively) when 70 and 80 MHz, three-cycle, and 26 dB_m input pulse waveforms are applied, respectively. The input 1-dB compression point (an index of linearity) of the HVPA with power MOSFET linearizer (24.17 and 26.19 dB_m at 70 and 80 MHz, respectively) at 10 V DC bias voltage was increased compared to that of HVPA without the power MOSFET linearizer (22.03 and 22.13 dB_m at 70 and 80 MHz, respectively). To further verify the reduction of the echo harmonic distortion components generated by the ultrasonic transducers, the pulse-echo responses in the pulse-echo instrumentation were compared when using HVPA with and without the power MOSFET linearizer. When three-cycle 26 dB_m input power was applied, the second, third, fourth, and fifth harmonic distortion components of a 75 MHz transducer driven by the HVPA with power MOSFET linearizer (−48.34, −44.21, −48.34, and −46.56 dB, respectively) were lower than that of the HVPA without the power MOSFET linearizer (−45.61, −41.57, −45.01, and −45.51 dB, respectively). When five-cycle 20 dB_m input power was applied, the second, third, fourth, and fifth harmonic distortions of the HVPA with the power MOSFET linearizer (−41.54, −41.80, −48.86, and −46.27 dB, respectively) were also lower than that of the HVPA without the power MOSFET linearizer (−25.85, −43.56, −49.04, and −49.24 dB, respectively). Therefore, we conclude that the power MOSFET linearizer could reduce gain deviation of the HVPA, thus reducing the echo signal harmonic distortions generated by the high-frequency ultrasonic transducers in pulse-echo instrumentation. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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13 pages, 3116 KiB

Open AccessArticle

Optimum Design Rules for CMOS Hall Sensors

by Marco Crescentini^1,2,*

, Michele Biondi², Aldo Romani^1,2

, Marco Tartagni^1,2 and Enrico Sangiorgi^1,2

¹ Department of Electrical, Electronic and Information Engineering “G. Marconi”—DEI, University of Bologna, Cesena Campus, Via Venezia 52, 47521 Cesena, Italy

² Advanced Research Center on Electronic Systems (ARCES), University of Bologna, Cesena Campus, Via Venezia 52, 47521 Cesena, Italy

Sensors 2017, 17(4), 765; https://doi.org/10.3390/s17040765 - 4 Apr 2017

Cited by 36 | Viewed by 7012

Abstract

This manuscript analyzes the effects of design parameters, such as aspect ratio, doping concentration and bias, on the performance of a general CMOS Hall sensor, with insight on current-related sensitivity, power consumption, and bandwidth. The article focuses on rectangular-shaped Hall probes since this [...] Read more.

This manuscript analyzes the effects of design parameters, such as aspect ratio, doping concentration and bias, on the performance of a general CMOS Hall sensor, with insight on current-related sensitivity, power consumption, and bandwidth. The article focuses on rectangular-shaped Hall probes since this is the most general geometry leading to shape-independent results. The devices are analyzed by means of 3D-TCAD simulations embedding galvanomagnetic transport model, which takes into account the Lorentz force acting on carriers due to a magnetic field. Simulation results define a set of trade-offs and design rules that can be used by electronic designers to conceive their own Hall probes. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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12 pages, 3901 KiB

Open AccessArticle

A New Method for Land Vehicle Gravimetry Using SINS/VEL

by Ruihang Yu, Meiping Wu^*, Kaidong Zhang, Shaokun Cai, Juliang Cao, Minghao Wang and Lin Wang

College of Mechatronics and Automation, National University of Defense Technology, Changsha 410073, China

Sensors 2017, 17(4), 766; https://doi.org/10.3390/s17040766 - 4 Apr 2017

Cited by 15 | Viewed by 4454

Abstract

The use of Global Navigation Satellite System (GNSS) data for land vehicle gravimetry tests is challenged by complicated environments. A new approach for land vehicle gravimetry using a Strapdown Inertial Navigation System and velometer-integrated navigation computation (SINS/VEL) without using GNSS information has been [...] Read more.

The use of Global Navigation Satellite System (GNSS) data for land vehicle gravimetry tests is challenged by complicated environments. A new approach for land vehicle gravimetry using a Strapdown Inertial Navigation System and velometer-integrated navigation computation (SINS/VEL) without using GNSS information has been put forward. Aided by the velometer with continuous longitudinal velocity output instead of GNSS signals, a SGA-WZ02 strapdown gravimeter that used the SINS/VEL method was tested in 2015. Four repeated lines were measured along a south-north direction highway in Eastern Changsha to verify the new method’s feasibility and performance. The gravity disturbance results showed an internal accuracy in scalar gravimetry about 1.17 mGal and 1.91 mGal for external accuracy assessment, with a spatial resolution of 1.7 km. Comparing this new method with the traditional SINS/GNSS gravimetry approach, it appeared that the results using SINS/VEL showed comparable internal and external accuracy. Theoretical analysis and practical test results showed that the new method was feasible for gravity determination by land dynamic vehicle. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 7034 KiB

Open AccessArticle

Enhancement of MCF Rubber Utilizing Electric and Magnetic Fields, and Clarification of Electrolytic Polymerization

by Kunio Shimada

Faculty of Symbiotic Systems Sciences, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan

Sensors 2017, 17(4), 767; https://doi.org/10.3390/s17040767 - 4 Apr 2017

Cited by 17 | Viewed by 4742

Abstract

Many sensors require mechanical durability to resist immense or impulsive pressure and large elasticity, so that they can be installed in or assimilated into the outer layer of artificial skin on robots. Given these demanding requirements, we adopted natural rubber (NR-latex) and developed [...] Read more.

Many sensors require mechanical durability to resist immense or impulsive pressure and large elasticity, so that they can be installed in or assimilated into the outer layer of artificial skin on robots. Given these demanding requirements, we adopted natural rubber (NR-latex) and developed a new method (NM) for curing NR-latex by the application of a magnetic field under electrolytic polymerization. The aim of the present work is to clarify the new manufacturing process for NR-latex embedded with magnetic compound fluid (MCF) as a conductive filler, and the contribution of the optimization of the new process for sensor. We first clarify the effect of the magnetic field on the enhancement of the NR-latex MCF rubber created by the alignment of magnetic clusters of MCF. Next, SEM, XRD, Raman spectroscopy, and XPS are used for morphological and microscopic observation of the electrolytically polymerized MCF rubber, and a chemical approach measuring pH and ORP of the MCF rubber liquid was used to investigate the process of electrolytic polymerization with a physical mode. We elucidate why the MCF rubber produced by the NM is enhanced with high sensitivity and long-term stability. This process of producing MCF rubber by the NM is closely related to the development of a highly sensitive sensor. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 2560 KiB

Open AccessArticle

Performance Evaluation and Analysis for Gravity Matching Aided Navigation

by Lin Wu¹

, Hubiao Wang¹, Hua Chai¹, Lu Zhang^1,2, Houtse Hsu¹ and Yong Wang^1,*

¹ State Key Laboratory of Geodesy and Earth’s Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China

² University of Chinese Academy of Sciences, Beijing 100049, China

Sensors 2017, 17(4), 769; https://doi.org/10.3390/s17040769 - 5 Apr 2017

Cited by 31 | Viewed by 5730

Abstract

Simulation tests were accomplished in this paper to evaluate the performance of gravity matching aided navigation (GMAN). Four essential factors were focused in this study to quantitatively evaluate the performance: gravity database (DB) resolution, fitting degree of gravity measurements, number of samples in [...] Read more.

Simulation tests were accomplished in this paper to evaluate the performance of gravity matching aided navigation (GMAN). Four essential factors were focused in this study to quantitatively evaluate the performance: gravity database (DB) resolution, fitting degree of gravity measurements, number of samples in matching, and gravity changes in the matching area. Marine gravity anomaly DB derived from satellite altimetry was employed. Actual dynamic gravimetry accuracy and operating conditions were referenced to design the simulation parameters. The results verified that the improvement of DB resolution, gravimetry accuracy, number of measurement samples, or gravity changes in the matching area generally led to higher positioning accuracies, while the effects of them were different and interrelated. Moreover, three typical positioning accuracy targets of GMAN were proposed, and the conditions to achieve these targets were concluded based on the analysis of several different system requirements. Finally, various approaches were provided to improve the positioning accuracy of GMAN. Full article

(This article belongs to the Special Issue Marine Sensing)

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14 pages, 2433 KiB

Open AccessArticle

A Two-Axis Goniometric Sensor for Tracking Finger Motion

by Lefan Wang, Turgut Meydan^*

and Paul Ieuan Williams

Wolfson Centre for Magnetics, School of Engineering, Cardiff University, Cardiff CF24 3AA, Wales, UK

Sensors 2017, 17(4), 770; https://doi.org/10.3390/s17040770 - 5 Apr 2017

Cited by 26 | Viewed by 14639

Abstract

The study of finger kinematics has developed into an important research area. Various hand tracking systems are currently available; however, they all have limited functionality. Generally, the most commonly adopted sensors are limited to measurements with one degree of freedom, i.e., flexion/extension of [...] Read more.

The study of finger kinematics has developed into an important research area. Various hand tracking systems are currently available; however, they all have limited functionality. Generally, the most commonly adopted sensors are limited to measurements with one degree of freedom, i.e., flexion/extension of fingers. More advanced measurements including finger abduction, adduction, and circumduction are much more difficult to achieve. To overcome these limitations, we propose a two-axis 3D printed optical sensor with a compact configuration for tracking finger motion. Based on Malus’ law, this sensor detects the angular changes by analyzing the attenuation of light transmitted through polarizing film. The sensor consists of two orthogonal axes each containing two pathways. The two readings from each axis are fused using a weighted average approach, enabling a measurement range up to 180

^{\circ}

and an improvement in sensitivity. The sensor demonstrates high accuracy (±0.3

^{\circ}

), high repeatability, and low hysteresis error. Attaching the sensor to the index finger’s metacarpophalangeal joint, real-time movements consisting of flexion/extension, abduction/adduction and circumduction have been successfully recorded. The proposed two-axis sensor has demonstrated its capability for measuring finger movements with two degrees of freedom and can be potentially used to monitor other types of body motion. Full article

(This article belongs to the Special Issue 3D Printed Sensors)

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24 pages, 1163 KiB

Open AccessArticle

Attack Classification Schema for Smart City WSNs

by Victor Garcia-Font^*

, Carles Garrigues

and Helena Rifà-Pous

Internet Interdisciplinary Institute (IN3), IT, Multimedia and Telecommunications Department, Universitat Oberta de Catalunya, Rambla del Poblenou 156, 08018 Barcelona, Spain

Sensors 2017, 17(4), 771; https://doi.org/10.3390/s17040771 - 5 Apr 2017

Cited by 41 | Viewed by 7805

Abstract

Urban areas around the world are populating their streets with wireless sensor networks (WSNs) in order to feed incipient smart city IT systems with metropolitan data. In the future smart cities, WSN technology will have a massive presence in the streets, and the [...] Read more.

Urban areas around the world are populating their streets with wireless sensor networks (WSNs) in order to feed incipient smart city IT systems with metropolitan data. In the future smart cities, WSN technology will have a massive presence in the streets, and the operation of municipal services will be based to a great extent on data gathered with this technology. However, from an information security point of view, WSNs can have failures and can be the target of many different types of attacks. Therefore, this raises concerns about the reliability of this technology in a smart city context. Traditionally, security measures in WSNs have been proposed to protect specific protocols in an environment with total control of a single network. This approach is not valid for smart cities, as multiple external providers deploy a plethora of WSNs with different security requirements. Hence, a new security perspective needs to be adopted to protect WSNs in smart cities. Considering security issues related to the deployment of WSNs as a main data source in smart cities, in this article, we propose an intrusion detection framework and an attack classification schema to assist smart city administrators to delimit the most plausible attacks and to point out the components and providers affected by incidents. We demonstrate the use of the classification schema providing a proof of concept based on a simulated selective forwarding attack affecting a parking and a sound WSN. Full article

(This article belongs to the Special Issue The Architectures, Systems, and Applications of Internet of Things for Smart Cities)

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11 pages, 10752 KiB

Open AccessArticle

Characteristics of N-Acylhomoserine Lactones Produced by Hafnia alvei H4 Isolated from Spoiled Instant Sea Cucumber

by Hong-Man Hou^1,2,*, Yao-Lei Zhu^1,2

, Jia-Ying Wang^1,2, Feng Jiang^1,2, Wen-Yan Qu^1,2

, Gong-Liang Zhang^1,2 and Hong-Shun Hao²

¹ School of Food Science and Technology, Dalian Polytechnic University, No. 1, Qinggongyuan, Ganjingzi District, Dalian 116034, China

² Liaoning Key Lab for Aquatic Processing Quality and Safety, No. 1, Qinggongyuan, Ganjingzi District, Dalian 116034, China

Sensors 2017, 17(4), 772; https://doi.org/10.3390/s17040772 - 5 Apr 2017

Cited by 38 | Viewed by 6345

Abstract

This study aimed to identify N-acylhomoserine lactone (AHL) produced by Hafnia alvei H4, which was isolated from spoiled instant sea cucumber, and to investigate the effect of AHLs on biofilm formation. Two biosensor strains, Chromobacterium violaceum CV026 and Agrobacterium tumefaciens KYC55, were [...] Read more.

This study aimed to identify N-acylhomoserine lactone (AHL) produced by Hafnia alvei H4, which was isolated from spoiled instant sea cucumber, and to investigate the effect of AHLs on biofilm formation. Two biosensor strains, Chromobacterium violaceum CV026 and Agrobacterium tumefaciens KYC55, were used to detect the quorum sensing (QS) activity of H. alvei H4 and to confirm the existence of AHL-mediated QS system. Thin layer chromatography (TLC) and high resolution triple quadrupole liquid chromatography/mass spectrometry (LC/MS) analysis of the AHLs extracted from the culture supernatant of H. alvei H4 revealed the existence of at least three AHLs: N-hexanoyl-l-homoserine lactone (C6-HSL), N-(3-oxo-octanoyl)-l-homoserine lactone (3-oxo-C8-HSL), and N-butyryl-l-homoserine lactone (C4-HSL). This is the first report of the production of C4-HSL by H. alvei. In order to determine the relationship between the production of AHL by H. alvei H4 and bacterial growth, the β-galactosidase assay was employed to monitor AHL activity during a 48-h growth phase. AHLs production reached a maximum level of 134.6 Miller unites at late log phase (after 18 h) and then decreased to a stable level of about 100 Miller unites. AHL production and bacterial growth displayed a similar trend, suggesting that growth of H. alvei H4 might be regulated by QS. The effect of AHLs on biofilm formation of H. alvei H4 was investigated by adding exogenous AHLs (C4-HSL, C6-HSL and 3-oxo-C8-HSL) to H. alvei H4 culture. Biofilm formation was significantly promoted (p < 0.05) by 5 and 10 µM C6-HSL, inhibited (p < 0.05) by C4-HSL (5 and 10 µM) and 5 µM 3-oxo-C8-HSL, suggesting that QS may have a regulatory role in the biofilm formation of H. alvei H4. Full article

(This article belongs to the Section Biosensors)

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18 pages, 7176 KiB

Open AccessArticle

A Force-Visualized Silicone Retractor Attachable to Surgical Suction Pipes

by Tetsuyou Watanabe^1,*

, Toshio Koyama¹, Takeshi Yoneyama¹ and Mitsutoshi Nakada²

¹ Institute of Science and Engineering, Kanazawa University, Kanazawa 9201192, Japan

² Department of Neurosurgery, Kanazawa University, Kanazawa 9208641, Japan

Sensors 2017, 17(4), 773; https://doi.org/10.3390/s17040773 - 5 Apr 2017

Cited by 7 | Viewed by 5773

Abstract

This paper presents a force-visually-observable silicone retractor, which is an extension of a previously developed system that had the same functions of retracting, suction, and force sensing. These features provide not only high usability by reducing the number of tool changes, but also [...] Read more.

This paper presents a force-visually-observable silicone retractor, which is an extension of a previously developed system that had the same functions of retracting, suction, and force sensing. These features provide not only high usability by reducing the number of tool changes, but also a safe choice of retracting by visualized force information. Suction is achieved by attaching the retractor to a suction pipe. The retractor has a deformable sensing component including a hole filled with a liquid. The hole is connected to an outer tube, and the liquid level displaced in proportion to the extent of deformation resulting from the retracting load. The liquid level is capable to be observed around the surgeon’s fingertips, which enhances the usability. The new hybrid structure of soft sensing and hard retracting allows the miniaturization of the retractor as well as a resolution of less than 0.05 N and a range of 0.1–0.7 N. The overall structure is made of silicone, which has the advantages of disposability, low cost, and easy sterilization/disinfection. This system was validated by conducting experiments. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 4436 KiB

Open AccessArticle

Analysis of Optimal Sensor Positions for Activity Classification and Application on a Different Data Collection Scenario

by Natthapon Pannurat¹, Surapa Thiemjarus^2,*, Ekawit Nantajeewarawat¹ and Isara Anantavrasilp³

¹ School of Information, Computer, and Communication Technology, Sirindhorn International Institute of Technology, Thammasat University, Pathumthani 12000, Thailand

² National Electronics and Computer Technology Center, Pathumthani 12120, Thailand

³ International College, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand

Sensors 2017, 17(4), 774; https://doi.org/10.3390/s17040774 - 5 Apr 2017

Cited by 34 | Viewed by 8871

Abstract

This paper focuses on optimal sensor positioning for monitoring activities of daily living and investigates different combinations of features and models on different sensor positions, i.e., the side of the waist, front of the waist, chest, thigh, head, upper arm, wrist, and ankle. [...] Read more.

This paper focuses on optimal sensor positioning for monitoring activities of daily living and investigates different combinations of features and models on different sensor positions, i.e., the side of the waist, front of the waist, chest, thigh, head, upper arm, wrist, and ankle. Nineteen features are extracted, and the feature importance is measured by using the Relief-F feature selection algorithm. Eight classification algorithms are evaluated on a dataset collected from young subjects and a dataset collected from elderly subjects, with two different experimental settings. To deal with different sampling rates, signals with a high data rate are down-sampled and a transformation matrix is used for aligning signals to the same coordinate system. The thigh, chest, side of the waist, and front of the waist are the best four sensor positions for the first dataset (young subjects), with average accuracy values greater than 96%. The best model obtained from the first dataset for the side of the waist is validated on the second dataset (elderly subjects). The most appropriate number of features for each sensor position is reported. The results provide a reference for building activity recognition models for different sensor positions, as well as for data acquired from different hardware platforms and subject groups. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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11 pages, 1239 KiB

Open AccessArticle

Performance Assessment of a Humidity Measurement System and Its Use to Evaluate Moisture Characteristics of Wheelchair Cushions at the User–Seat Interface

by Zhuofu Liu^1,*, Haifeng Cheng¹, Zhongming Luo¹, Vincenzo Cascioli², Andrew I. Heusch³, Nadia R. Nair³ and Peter W. McCarthy⁴

¹ The Higher Educational Key Laboratory for Measuring & Control Technology and Instrumentations of Heilongjiang Province, Harbin University of Science and Technology, Harbin 150080, China

² Murdoch University Chiropractic Clinic, Murdoch University, Murdoch 6150, Australia

³ Welsh Institute of Chiropractic, University of South Wales, Treforest, Pontypridd CF37 1DL, UK

⁴ Faculty of Life Science and Education, University of South Wales, Treforest, Pontypridd CF37 1DL, UK

Sensors 2017, 17(4), 775; https://doi.org/10.3390/s17040775 - 5 Apr 2017

Cited by 7 | Viewed by 4258

Abstract

Little is known about the changes in moisture that occur at the body–seat interface during sitting. However, as increased moisture can add to the risk of skin damage, we have developed an array of MEMS (Micro-Electro-Mechanical System) humidity sensors to measure at this [...] Read more.

Little is known about the changes in moisture that occur at the body–seat interface during sitting. However, as increased moisture can add to the risk of skin damage, we have developed an array of MEMS (Micro-Electro-Mechanical System) humidity sensors to measure at this interface. Sensors were first evaluated against traceable standards, followed by use in a cross-over field test (n = 11; 20 min duration) using different wheelchair cushions (foam and gel). Relative humidity (RH) was measured at the left mid-thigh, right mid-thigh and coccyx. Sensors were shown to be unaffected by loading and showed highly reliable responses to measured changes in humidity, varying little from the traceable standard (<5%). Field-test data, smoothed through a moving average filter, revealed significant differences between the three chosen locations and between the gel and foam cushions. Maximum RH was attained in less than five minutes regardless of cushion material (foam or gel). Importantly, RH does not appear to distribute uniformly over the body–seat interface; suggesting multiple sensor positions would appear essential for effectively monitoring moisture in this interface. Material properties of the cushions appear to have a significant effect on RH characteristics (profile) at the body–seat interface, but not necessarily the time to peak moisture. Full article

(This article belongs to the Special Issue Humidity Sensors)

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17 pages, 2966 KiB

Open AccessArticle

Assessment of the Indoor Odour Impact in a Naturally Ventilated Room

by Lidia Eusebio

, Marco Derudi

, Laura Capelli

, Giuseppe Nano and Selena Sironi^*

Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica “G. Natta”, P.za Leonardo da Vinci 32, 20133 Milano, Italy

Sensors 2017, 17(4), 778; https://doi.org/10.3390/s17040778 - 5 Apr 2017

Cited by 17 | Viewed by 5104

Abstract

Indoor air quality influences people’s lives, potentially affecting their health and comfort. Nowadays, ventilation is the only technique commonly used for regulating indoor air quality. CO₂ is the reference species considered in order to calculate the air exchange rates of indoor environments. [...] Read more.

Indoor air quality influences people’s lives, potentially affecting their health and comfort. Nowadays, ventilation is the only technique commonly used for regulating indoor air quality. CO₂ is the reference species considered in order to calculate the air exchange rates of indoor environments. Indeed, regarding air quality, the presence of pleasant or unpleasant odours can strongly influence the environmental comfort. In this paper, a case study of indoor air quality monitoring is reported. The indoor field tests were conducted measuring both CO₂ concentration, using a photoacoustic multi-gas analyzer, and odour trends, using an electronic nose, in order to analyze and compare the information acquired. The indoor air monitoring campaign was run for a period of 20 working days into a university room. The work was focused on the determination of both CO₂ and odour emission factors (OEF) emitted by the human activity and on the evaluation of the odour impact in a naturally ventilated room. The results highlighted that an air monitoring and recycling system based only on CO₂ concentration and temperature measurements might be insufficient to ensure a good indoor air quality, whereas its performances could be improved by integrating the existing systems with an electronic nose for odour detection. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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11 pages, 1450 KiB

Open AccessArticle

Accurate Simulation of Parametrically Excited Micromirrors via Direct Computation of the Electrostatic Stiffness

by Attilio Frangi^1,*

, Andrea Guerrieri¹ and Nicoló Boni²

¹ Department of Civil and Environmental Engng., Politecnico di Milano, 20133 Milano, Italy

² MSH Division, ST Microelectronics, 20010 Cornaredo (MI), Italy

Sensors 2017, 17(4), 779; https://doi.org/10.3390/s17040779 - 6 Apr 2017

Cited by 12 | Viewed by 4705

Abstract

Electrostatically actuated torsional micromirrors are key elements in Micro-Opto-Electro- Mechanical-Systems. When forced by means of in-plane comb-fingers, the dynamics of the main torsional response is known to be strongly non-linear and governed by parametric resonance. Here, in order to also trace unstable branches [...] Read more.

Electrostatically actuated torsional micromirrors are key elements in Micro-Opto-Electro- Mechanical-Systems. When forced by means of in-plane comb-fingers, the dynamics of the main torsional response is known to be strongly non-linear and governed by parametric resonance. Here, in order to also trace unstable branches of the mirror response, we implement a simplified continuation method with arc-length control and propose an innovative technique based on Finite Elements and the concepts of material derivative in order to compute the electrostatic stiffness; i.e., the derivative of the torque with respect to the torsional angle, as required by the continuation approach. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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23 pages, 3821 KiB

Open AccessArticle

A QoS Optimization Approach in Cognitive Body Area Networks for Healthcare Applications

by Tauseef Ahmed^* and Yannick Le Moullec

Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia

Sensors 2017, 17(4), 780; https://doi.org/10.3390/s17040780 - 6 Apr 2017

Cited by 22 | Viewed by 5480

Abstract

Wireless body area networks are increasingly featuring cognitive capabilities. This work deals with the emerging concept of cognitive body area networks. In particular, the paper addresses two important issues, namely spectrum sharing and interferences. We propose methods for channel and power allocation. The [...] Read more.

Wireless body area networks are increasingly featuring cognitive capabilities. This work deals with the emerging concept of cognitive body area networks. In particular, the paper addresses two important issues, namely spectrum sharing and interferences. We propose methods for channel and power allocation. The former builds upon a reinforcement learning mechanism, whereas the latter is based on convex optimization. Furthermore, we also propose a mathematical channel model for off-body communication links in line with the IEEE 802.15.6 standard. Simulation results for a nursing home scenario show that the proposed approach yields the best performance in terms of throughput and QoS for dynamic environments. For example, in a highly demanding scenario our approach can provide throughput up to 7 Mbps, while giving an average of 97.2% of time QoS satisfaction in terms of throughput. Simulation results also show that the power optimization algorithm enables reducing transmission power by approximately 4.5 dBm, thereby sensibly and significantly reducing interference. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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12 pages, 1955 KiB

Open AccessArticle

The Physical Layer Security Experiments of Cooperative Communication System with Different Relay Behaviors

by Yishan Su^1,2, Guangyao Han², Xiaomei Fu^1,2,*

, Naishen Xu² and Zhigang Jin²

¹ School of Marine Science and Technology, Tianjin University, 300072 Tianjin, China

² School of Electrical Automation and Information Engineering, Tianjin University, 300072 Tianjin, China

Sensors 2017, 17(4), 781; https://doi.org/10.3390/s17040781 - 6 Apr 2017

Cited by 5 | Viewed by 4033

Abstract

Physical layer security is an attractive security mechanism, which exploits the randomness characteristics of wireless transmission channel to achieve security. However, it is hampered by the limitation of the channel condition that the main channel must be better than the eavesdropper channel. To [...] Read more.

Physical layer security is an attractive security mechanism, which exploits the randomness characteristics of wireless transmission channel to achieve security. However, it is hampered by the limitation of the channel condition that the main channel must be better than the eavesdropper channel. To alleviate the limitation, cooperative communication is introduced. Few studies have investigated the physical layer security of the relay transmission model. In this paper, we performed some experiments to evaluate the physical layer security of a cooperative communication system, with a relay operating in decode-and-forward (DF) cooperative mode, selfish and malicious behavior in real non-ideal transmission environment. Security performance is evaluated in terms of the probability of non-zero secrecy capacity. Experiments showed some different results compared to theoretical simulation: (1) to achieve the maximum secrecy capacity, the optimal relay power according to the experiments result is larger than that of ideal theoretical results under both cooperative and selfish behavior relay; (2) the relay in malicious behavior who forwards noise to deteriorate the main channel may deteriorate the eavesdropper channel more seriously than the main channel; (3) the optimal relay positions under cooperative and selfish behavior relay cases are both located near the destination because of non-ideal transmission. Full article

(This article belongs to the Section Sensor Networks)

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12 pages, 2958 KiB

Open AccessArticle

Mover Position Detection for PMTLM Based on Linear Hall Sensors through EKF Processing

by Leyang Yan¹, Hui Zhang¹ and Peiqing Ye^1,2,*

¹ Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China

² State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(4), 782; https://doi.org/10.3390/s17040782 - 6 Apr 2017

Cited by 9 | Viewed by 4775

Abstract

Accurate mover position is vital for a permanent magnet tubular linear motor (PMTLM) control system. In this paper, two linear Hall sensors are utilized to detect the mover position. However, Hall sensor signals contain third-order harmonics, creating errors in mover position detection. To [...] Read more.

Accurate mover position is vital for a permanent magnet tubular linear motor (PMTLM) control system. In this paper, two linear Hall sensors are utilized to detect the mover position. However, Hall sensor signals contain third-order harmonics, creating errors in mover position detection. To filter out the third-order harmonics, a signal processing method based on the extended Kalman filter (EKF) is presented. The limitation of conventional processing method is first analyzed, and then EKF is adopted to detect the mover position. In the EKF model, the amplitude of the fundamental component and the percentage of the harmonic component are taken as state variables, and they can be estimated based solely on the measured sensor signals. Then, the harmonic component can be calculated and eliminated. The proposed method has the advantages of faster convergence, better stability and higher accuracy. Finally, experimental results validate the effectiveness and superiority of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 1455 KiB

Open AccessArticle

Identification of Mobile Phones Using the Built-In Magnetometers Stimulated by Motion Patterns

by Gianmarco Baldini^1,2,*

, Franc Dimc³

, Roman Kamnik⁴, Gary Steri¹

, Raimondo Giuliani¹

and Claudio Gentile²

¹ European Commission, Joint Research Centre, Ispra 21027, Italy

² DiSTA, University of Insubria, Varese 21100, Italy

³ Faculty of Maritime Studies and Transport, University of Ljubljana, Portorož 6320, Slovenia

⁴ Faculty of Electrical Engineering, University of Ljubljana, Ljubljana SI 1000, Slovenia

Sensors 2017, 17(4), 783; https://doi.org/10.3390/s17040783 - 6 Apr 2017

Cited by 20 | Viewed by 6153

Abstract

We investigate the identification of mobile phones through their built-in magnetometers. These electronic components have started to be widely deployed in mass market phones in recent years, and they can be exploited to uniquely identify mobile phones due their physical differences, which appear [...] Read more.

We investigate the identification of mobile phones through their built-in magnetometers. These electronic components have started to be widely deployed in mass market phones in recent years, and they can be exploited to uniquely identify mobile phones due their physical differences, which appear in the digital output generated by them. This is similar to approaches reported in the literature for other components of the mobile phone, including the digital camera, the microphones or their RF transmission components. In this paper, the identification is performed through an inexpensive device made up of a platform that rotates the mobile phone under test and a fixed magnet positioned on the edge of the rotating platform. When the mobile phone passes in front of the fixed magnet, the built-in magnetometer is stimulated, and its digital output is recorded and analyzed. For each mobile phone, the experiment is repeated over six different days to ensure consistency in the results. A total of 10 phones of different brands and models or of the same model were used in our experiment. The digital output from the magnetometers is synchronized and correlated, and statistical features are extracted to generate a fingerprint of the built-in magnetometer and, consequently, of the mobile phone. A SVM machine learning algorithm is used to classify the mobile phones on the basis of the extracted statistical features. Our results show that inter-model classification (i.e., different models and brands classification) is possible with great accuracy, but intra-model (i.e., phones with different serial numbers and same model) classification is more challenging, the resulting accuracy being just slightly above random choice. Full article

(This article belongs to the Special Issue Magnetoelectric Heterostructures and Sensors)

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8 pages, 2885 KiB

Open AccessArticle

Refractive Index Sensor Based on Fano Resonances in Metal-Insulator-Metal Waveguides Coupled with Resonators

by Yue Tang^1,†, Zhidong Zhang^1,†

, Ruibing Wang¹, Zhenyin Hai², Chenyang Xue¹, Wendong Zhang¹

and Shubin Yan^1,*

¹ Science and Technology on Electronic Test and Measurement Laboratory, North University of China, No. 3 Xueyuan Road, Taiyuan 030051, China

² Ghent University Global Campus, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, 119 Songdo Munhwa-ro, Yeonsu-Gu, Incheon 406-840, Korea

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 784; https://doi.org/10.3390/s17040784 - 6 Apr 2017

Cited by 113 | Viewed by 8811

Abstract

A surface plasmon polariton refractive index sensor based on Fano resonances in metal–insulator–metal (MIM) waveguides coupled with rectangular and ring resonators is proposed and numerically investigated using a finite element method. Fano resonances are observed in the transmission spectra, which result from the [...] Read more.

A surface plasmon polariton refractive index sensor based on Fano resonances in metal–insulator–metal (MIM) waveguides coupled with rectangular and ring resonators is proposed and numerically investigated using a finite element method. Fano resonances are observed in the transmission spectra, which result from the coupling between the narrow-band spectral response in the ring resonator and the broadband spectral response in the rectangular resonator. Results are analyzed using coupled-mode theory based on transmission line theory. The coupled mode theory is employed to explain the Fano resonance effect, and the analytical result is in good agreement with the simulation result. The results show that with an increase in the refractive index of the fill dielectric material in the slot of the system, the Fano resonance peak exhibits a remarkable red shift, and the highest value of sensitivity (S) is 1125 nm/RIU, RIU means refractive index unit. Furthermore, the coupled MIM waveguide structure can be integrated with other photonic devices at the chip scale. The results can provide a guide for future applications of this structure. Full article

(This article belongs to the Special Issue Acoustic Wave Resonator-Based Sensors)

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19 pages, 2149 KiB

Open AccessArticle

Robust Multi-Frame Adaptive Optics Image Restoration Algorithm Using Maximum Likelihood Estimation with Poisson Statistics

by Dongming Li^1,2,3

, Changming Sun³

, Jinhua Yang², Huan Liu¹, Jiaqi Peng¹ and Lijuan Zhang^3,4,*

¹ School of Information Technology, Jilin Agricultural University, Changchun 130118, China

² School of Opto-Electronic Engineering, Changchun University of Science and Technology, Changchun 130022, China

³ CSIRO Data61, PO Box 76, Epping, NSW 1710, Australia

⁴ College of Computer Science and Engineering, Changchun University of Technology, Changchun 130012, China

Sensors 2017, 17(4), 785; https://doi.org/10.3390/s17040785 - 6 Apr 2017

Cited by 12 | Viewed by 5315

Abstract

An adaptive optics (AO) system provides real-time compensation for atmospheric turbulence. However, an AO image is usually of poor contrast because of the nature of the imaging process, meaning that the image contains information coming from both out-of-focus and in-focus planes of the [...] Read more.

An adaptive optics (AO) system provides real-time compensation for atmospheric turbulence. However, an AO image is usually of poor contrast because of the nature of the imaging process, meaning that the image contains information coming from both out-of-focus and in-focus planes of the object, which also brings about a loss in quality. In this paper, we present a robust multi-frame adaptive optics image restoration algorithm via maximum likelihood estimation. Our proposed algorithm uses a maximum likelihood method with image regularization as the basic principle, and constructs the joint log likelihood function for multi-frame AO images based on a Poisson distribution model. To begin with, a frame selection method based on image variance is applied to the observed multi-frame AO images to select images with better quality to improve the convergence of a blind deconvolution algorithm. Then, by combining the imaging conditions and the AO system properties, a point spread function estimation model is built. Finally, we develop our iterative solutions for AO image restoration addressing the joint deconvolution issue. We conduct a number of experiments to evaluate the performances of our proposed algorithm. Experimental results show that our algorithm produces accurate AO image restoration results and outperforms the current state-of-the-art blind deconvolution methods. Full article

(This article belongs to the Section Physical Sensors)

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23 pages, 6885 KiB

Open AccessArticle

Sensor Fusion of a Mobile Device to Control and Acquire Videos or Images of Coffee Branches and for Georeferencing Trees

by Paula Jimena Ramos Giraldo^1,2,*

, Álvaro Guerrero Aguirre¹

, Carlos Mario Muñoz², Flavio Augusto Prieto²

and Carlos Eugenio Oliveros¹

¹ Centro Nacional de Investigaciones de Café, Manizales 170009, Colombia

² Universidad Nacional de Colombia, Bogotá 11001, Colombia

Sensors 2017, 17(4), 786; https://doi.org/10.3390/s17040786 - 6 Apr 2017

Cited by 6 | Viewed by 6530

Abstract

Smartphones show potential for controlling and monitoring variables in agriculture. Their processing capacity, instrumentation, connectivity, low cost, and accessibility allow farmers (among other users in rural areas) to operate them easily with applications adjusted to their specific needs. In this investigation, the integration [...] Read more.

Smartphones show potential for controlling and monitoring variables in agriculture. Their processing capacity, instrumentation, connectivity, low cost, and accessibility allow farmers (among other users in rural areas) to operate them easily with applications adjusted to their specific needs. In this investigation, the integration of inertial sensors, a GPS, and a camera are presented for the monitoring of a coffee crop. An Android-based application was developed with two operating modes: (i) Navigation: for georeferencing trees, which can be as close as 0.5 m from each other; and (ii) Acquisition: control of video acquisition, based on the movement of the mobile device over a branch, and measurement of image quality, using clarity indexes to select the most appropriate frames for application in future processes. The integration of inertial sensors in navigation mode, shows a mean relative error of ±0.15 m, and total error ±5.15 m. In acquisition mode, the system correctly identifies the beginning and end of mobile phone movement in 99% of cases, and image quality is determined by means of a sharpness factor which measures blurriness. With the developed system, it will be possible to obtain georeferenced information about coffee trees, such as their production, nutritional state, and presence of plagues or diseases. Full article

(This article belongs to the Special Issue Precision Agriculture and Remote Sensing Data Fusion)

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19 pages, 2680 KiB

Open AccessArticle

Measuring Complexity and Predictability of Time Series with Flexible Multiscale Entropy for Sensor Networks

by Renjie Zhou^1,2, Chen Yang^1,2, Jian Wan^1,2,*, Wei Zhang^1,2, Bo Guan^3,* and Naixue Xiong^4,*

¹ School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou 310018, China

² Key Laboratory of Complex Systems Modeling and Simulation of Ministry of Education, Hangzhou Dianzi University, Hangzhou 310018, China

³ School of Electronic and Information Engineer, Ningbo University of Technology, Ningbo 315211, China

⁴ Department of Mathematics and Computer Science, Northeastern State University, Tahlequah, OK 74464, USA

Sensors 2017, 17(4), 787; https://doi.org/10.3390/s17040787 - 6 Apr 2017

Cited by 14 | Viewed by 4920

Abstract

Measurement of time series complexity and predictability is sometimes the cornerstone for proposing solutions to topology and congestion control problems in sensor networks. As a method of measuring time series complexity and predictability, multiscale entropy (MSE) has been widely applied in many fields. [...] Read more.

Measurement of time series complexity and predictability is sometimes the cornerstone for proposing solutions to topology and congestion control problems in sensor networks. As a method of measuring time series complexity and predictability, multiscale entropy (MSE) has been widely applied in many fields. However, sample entropy, which is the fundamental component of MSE, measures the similarity of two subsequences of a time series with either zero or one, but without in-between values, which causes sudden changes of entropy values even if the time series embraces small changes. This problem becomes especially severe when the length of time series is getting short. For solving such the problem, we propose flexible multiscale entropy (FMSE), which introduces a novel similarity function measuring the similarity of two subsequences with full-range values from zero to one, and thus increases the reliability and stability of measuring time series complexity. The proposed method is evaluated on both synthetic and real time series, including white noise, 1/f noise and real vibration signals. The evaluation results demonstrate that FMSE has a significant improvement in reliability and stability of measuring complexity of time series, especially when the length of time series is short, compared to MSE and composite multiscale entropy (CMSE). The proposed method FMSE is capable of improving the performance of time series analysis based topology and traffic congestion control techniques. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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8 pages, 2407 KiB

Open AccessArticle

Quantitative Detection of NADH Using a Novel Enzyme-Assisted Method Based on Surface-Enhanced Raman Scattering

by Haiyan Teng¹, Mingyang Lv¹, Luo Liu¹, Xin Zhang^1,*

, Yongmei Zhao², Zhenglong Wu³ and Haijun Xu^1,*

¹ Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029, China

² Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China

³ Analytical and Testing Center, Beijing Normal University, Beijing 100875, China

Sensors 2017, 17(4), 788; https://doi.org/10.3390/s17040788 - 7 Apr 2017

Cited by 9 | Viewed by 5609

Abstract

An enzymatic method for quantitative detection of the reduced form of nicotinamide-adenine dinucleotide (NADH) using surface-enhanced Raman scattering was developed. Under the action of NADH oxidase and horseradish peroxidase, NADH can generate hydrogen peroxide (H₂O₂) in a 1:1 molar [...] Read more.

An enzymatic method for quantitative detection of the reduced form of nicotinamide-adenine dinucleotide (NADH) using surface-enhanced Raman scattering was developed. Under the action of NADH oxidase and horseradish peroxidase, NADH can generate hydrogen peroxide (H₂O₂) in a 1:1 molar ratio, and the H₂O₂ can oxidize a chromogen into pigment with a 1:1 molar ratio. Therefore, the concentration of NADH can be determined by detecting the generated pigment. In our experiments, eight chromogens were studied, and o-tolidine (OT) was selected because of the unique Raman peaks displayed by its corresponding pigment. The optimal OT concentration was 2 × 10⁻³ M, and this gave the best linear relationship and the widest linear range between the logarithmic H₂O₂ concentration and the logarithmic integrated SERS intensity of the peak centered at 1448 cm⁻¹. Under this condition, the limit of detection for NADH was as low as 4 × 10⁻⁷ M. Two NADH samples with concentrations of 2 × 10⁻⁴ and 2 × 10⁻⁵ M were used to validate the linear relationship, and the logarithmic deviations were less than 3%. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 8719 KiB

Open AccessArticle

The Identification of the Deformation Stage of a Metal Specimen Based on Acoustic Emission Data Analysis

by Shenao Zou¹, Fengying Yan², Guoan Yang^1,* and Wei Sun^2,*

¹ College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing 100029, China

² Beijing Key Lab of Membrane Science and Technology, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China

Sensors 2017, 17(4), 789; https://doi.org/10.3390/s17040789 - 7 Apr 2017

Cited by 18 | Viewed by 4443

Abstract

The acoustic emission (AE) signals of metal materials have been widely used to identify the deformation stage of a pressure vessel. In this work, Q235 steel samples with different propagation distances and geometrical structures are stretched to get the corresponding acoustic emission signals. [...] Read more.

The acoustic emission (AE) signals of metal materials have been widely used to identify the deformation stage of a pressure vessel. In this work, Q235 steel samples with different propagation distances and geometrical structures are stretched to get the corresponding acoustic emission signals. Then the obtained acoustic emission signals are de-noised by empirical mode decomposition (EMD), and then decomposed into two different frequency ranges, i.e., one mainly corresponding to metal deformation and the other mainly corresponding to friction signals. The ratio of signal energy between two frequency ranges is defined as a new acoustic emission characteristic parameter. Differences can be observed at different deformation stages in both magnitude and data distribution range. Compared with other acoustic emission parameters, the proposed parameter is valid in different setups of the propagation medium and the coupled stiffness. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 4587 KiB

Open AccessArticle

In Vivo Bioimpedance Spectroscopy Characterization of Healthy, Hemorrhagic and Ischemic Rabbit Brain within 10 Hz–1 MHz

by Lin Yang¹, Wenbo Liu², Rongqing Chen¹, Ge Zhang¹, Weichen Li¹, Feng Fu^1,* and Xiuzhen Dong^1,*

¹ Department of Biomedical Engineering, Fourth Military Medical University, Xi’an 710032, China

² Department of Neurosurgery, Xijing hospital, Fourth Military Medical University, Xi’an 710032, China

Sensors 2017, 17(4), 791; https://doi.org/10.3390/s17040791 - 7 Apr 2017

Cited by 28 | Viewed by 6376

Abstract

Acute stroke is a serious cerebrovascular disease and has been the second leading cause of death worldwide. Conventional diagnostic modalities for stroke, such as CT and MRI, may not be available in emergency settings. Hence, it is imperative to develop a portable tool [...] Read more.

Acute stroke is a serious cerebrovascular disease and has been the second leading cause of death worldwide. Conventional diagnostic modalities for stroke, such as CT and MRI, may not be available in emergency settings. Hence, it is imperative to develop a portable tool to diagnose stroke in a timely manner. Since there are differences in impedance spectra between normal, hemorrhagic and ischemic brain tissues, multi-frequency electrical impedance tomography (MFEIT) shows great promise in detecting stroke. Measuring the impedance spectra of healthy, hemorrhagic and ischemic brain in vivo is crucial to the success of MFEIT. To our knowledge, no research has established hemorrhagic and ischemic brain models in the same animal and comprehensively measured the in vivo impedance spectra of healthy, hemorrhagic and ischemic brain within 10 Hz–1 MHz. In this study, the intracerebral hemorrhage and ischemic models were established in rabbits, and then the impedance spectra of healthy, hemorrhagic and ischemic brain were measured in vivo and compared. The results demonstrated that the impedance spectra differed significantly between healthy and stroke-affected brain (i.e., hemorrhagic or ischemic brain). Moreover, the rate of change in brain impedance following hemorrhagic and ischemic stroke with regard to frequency was distinct. These findings further validate the feasibility of using MFEIT to detect stroke and differentiate stroke types, and provide data supporting for future research. Full article

(This article belongs to the Section Biosensors)

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17 pages, 645 KiB

Open AccessArticle

Analysis and Tools for Improved Management of Connectionless and Connection-Oriented BLE Devices Coexistence

by Antonio Del Campo^*

, Lorenzo Cintioni, Susanna Spinsante

and Ennio Gambi

Dipartimento di Ingegneria dell’Informazione, Università Politecnica delle Marche, Via Brecce Bianche 12, Ancona 60131, Italy

Sensors 2017, 17(4), 792; https://doi.org/10.3390/s17040792 - 7 Apr 2017

Cited by 9 | Viewed by 4677

Abstract

With the introduction of low-power wireless technologies, like Bluetooth Low Energy (BLE), new applications are approaching the home automation, healthcare, fitness, automotive and consumer electronics markets. BLE devices are designed to maximize the battery life, i.e., to run for long time on a [...] Read more.

With the introduction of low-power wireless technologies, like Bluetooth Low Energy (BLE), new applications are approaching the home automation, healthcare, fitness, automotive and consumer electronics markets. BLE devices are designed to maximize the battery life, i.e., to run for long time on a single coin-cell battery. In typical application scenarios of home automation and Ambient Assisted Living (AAL), the sensors that monitor relatively unpredictable and rare events should coexist with other sensors that continuously communicate health or environmental parameter measurements. The former usually work in connectionless mode, acting as advertisers, while the latter need a persistent connection, acting as slave nodes. The coexistence of connectionless and connection-oriented networks, that share the same central node, can be required to reduce the number of handling devices, thus keeping the network complexity low and limiting the packet’s traffic congestion. In this paper, the medium access management, operated by the central node, has been modeled, focusing on the scheduling procedure in both connectionless and connection-oriented communication. The models have been merged to provide a tool supporting the configuration design of BLE devices, during the network design phase that precedes the real implementation. The results highlight the suitability of the proposed tool: the ability to set the device parameters to allow us to keep a practical discovery latency for event-driven sensors and avoid undesired overlaps between scheduled scanning and connection phases due to bad management performed by the central node. Full article

(This article belongs to the Special Issue Sensors for Home Automation and Security)

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14 pages, 1286 KiB

Open AccessArticle

A Novel Robust Trilateration Method Applied to Ultra-Wide Bandwidth Location Systems

by Jiahong Li

, Xianghu Yue, Jie Chen^* and Fang Deng^*

Key Laboratory of Intelligent Control and Decision of Complex Systems, School of Automation, Beijing Institute of Technology, Beijing 100081, China

Sensors 2017, 17(4), 795; https://doi.org/10.3390/s17040795 - 7 Apr 2017

Cited by 43 | Viewed by 5921

Abstract

Due to the non-line-of-sight (NLOS) and multipath fading channel (MPF) of the wireless networks, the non-existence of the intersection point often occurs in the range-based localization methods, e.g., the centroid-based trilateration method. To alleviate the problem, a confidence-based intersection method which expands the [...] Read more.

Due to the non-line-of-sight (NLOS) and multipath fading channel (MPF) of the wireless networks, the non-existence of the intersection point often occurs in the range-based localization methods, e.g., the centroid-based trilateration method. To alleviate the problem, a confidence-based intersection method which expands the range of the circle within a certain confidence interval is proposed. In the method, the confidence interval is estimated based on the Cramér–Rao lower bound of the time of flight (TOF) measurement. Furthermore, an intersection determination method is proposed to select the intersection point with higher confidence level. The simulation and experimental results show the superiority of the proposed method in localization accuracy and robustness to noise compared to the conventional trilateration method, e.g., the centroid-based and least squares based trilateration methods. Full article

(This article belongs to the Special Issue Sensors and Sensing in Indoor Localization, Tracking, Navigation and Activity Monitoring)

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15 pages, 1674 KiB

Open AccessArticle

Characteristics of the BDS Carrier Phase Multipath and Its Mitigation Methods in Relative Positioning

by Wujiao Dai^*, Qiang Shi

and Changsheng Cai

Department of Surveying and Geo-informatics, Central South University, Changsha 410083, China

Sensors 2017, 17(4), 796; https://doi.org/10.3390/s17040796 - 7 Apr 2017

Cited by 25 | Viewed by 4912

Abstract

The carrier phase multipath effect is one of the most significant error sources in the precise positioning of BeiDou Navigation Satellite System (BDS). We analyzed the characteristics of BDS multipath, and found the multipath errors of geostationary earth orbit (GEO) satellite signals are [...] Read more.

The carrier phase multipath effect is one of the most significant error sources in the precise positioning of BeiDou Navigation Satellite System (BDS). We analyzed the characteristics of BDS multipath, and found the multipath errors of geostationary earth orbit (GEO) satellite signals are systematic, whereas those of inclined geosynchronous orbit (IGSO) or medium earth orbit (MEO) satellites are both systematic and random. The modified multipath mitigation methods, including sidereal filtering algorithm and multipath hemispherical map (MHM) model, were used to improve BDS dynamic deformation monitoring. The results indicate that the sidereal filtering methods can reduce the root mean square (RMS) of positioning errors in the east, north and vertical coordinate directions by 15%, 37%, 25% and 18%, 51%, 27% in the coordinate and observation domains, respectively. By contrast, the MHM method can reduce the RMS by 22%, 52% and 27% on average. In addition, the BDS multipath errors in static baseline solutions are a few centimeters in multipath-rich environments, which is different from that of Global Positioning System (GPS) multipath. Therefore, we add a parameter representing the GEO multipath error in observation equation to the adjustment model to improve the precision of BDS static baseline solutions. And the results show that the modified model can achieve an average precision improvement of 82%, 54% and 68% in the east, north and up coordinate directions, respectively. Full article

(This article belongs to the Section Remote Sensors)

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18 pages, 639 KiB

Open AccessArticle

A Survey on Mobility Support in Wireless Body Area Networks

by Beom-Su Kim¹, Kyong Hoon Kim¹

and Ki-Il Kim^2,*

¹ Department of Informatics, Gyeongsang National University, Jinju 52828, Korea

² Department of Computer Science and Engineering, Chungnam National University, Daejeon 34134, Korea

Sensors 2017, 17(4), 797; https://doi.org/10.3390/s17040797 - 7 Apr 2017

Cited by 47 | Viewed by 6561

Abstract

Wireless Body Area Networks (WBANs) have attracted research interests from the community, as more promising healthcare applications have a tendency to employ them as underlying network technology. While taking design issues, such as small size hardware as well as low power computing, into [...] Read more.

Wireless Body Area Networks (WBANs) have attracted research interests from the community, as more promising healthcare applications have a tendency to employ them as underlying network technology. While taking design issues, such as small size hardware as well as low power computing, into account, a lot of research has been proposed to accomplish the given tasks in WBAN. However, since most of the existing works are basically developed by assuming all nodes in the static state, these schemes therefore cannot be applied in real scenarios where network topology between sensor nodes changes frequently and unexpectedly according to human moving behavior. However, as far as the authors know, there is no survey paper to focus on research challenges for mobility support in WBAN yet. To address this deficiency, in this paper, we present the state-of-the-art approaches and discuss the important features of related to mobility in WBAN. We give an overview of mobility model and categorize the models as individual and group. Furthermore, an overview of networking techniques in the recent literature and summary are compiled for comparison in several aspects. The article also suggests potential directions for future research in the field. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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13 pages, 10982 KiB

Open AccessArticle

EasyPCC: Benchmark Datasets and Tools for High-Throughput Measurement of the Plant Canopy Coverage Ratio under Field Conditions

by Wei Guo¹

, Bangyou Zheng², Tao Duan^2,3, Tokihiro Fukatsu⁴, Scott Chapman^2,5 and Seishi Ninomiya^1,*

¹ International Field Phenomics Laboratory, Institute for Sustainable Agro-ecosystem Services, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Midori-cho, Nishitokyo, Tokyo 188-0002, Japan

² CSIRO Agriculture & Food, Queensland Biosciences Precinct, 306 Carmody Rd., St. Lucia, QLD 4067, Australia

³ Institute College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China

⁴ Institute of Agricultural Machinery, National Agriculture and Food Research Organization, Kannondai 1-31-1, Tsukuba-shi, Ibaraki 305-0856, Japan

⁵ School of Agriculture and Food Sciences, Building 8117A NRSM, The University of Queensland, Gatton, QLD 4343, Australia

Sensors 2017, 17(4), 798; https://doi.org/10.3390/s17040798 - 7 Apr 2017

Cited by 59 | Viewed by 10079

Abstract

Understanding interactions of genotype, environment, and management under field conditions is vital for selecting new cultivars and farming systems. Image analysis is considered a robust technique in high-throughput phenotyping with non-destructive sampling. However, analysis of digital field-derived images remains challenging because of the [...] Read more.

Understanding interactions of genotype, environment, and management under field conditions is vital for selecting new cultivars and farming systems. Image analysis is considered a robust technique in high-throughput phenotyping with non-destructive sampling. However, analysis of digital field-derived images remains challenging because of the variety of light intensities, growth environments, and developmental stages. The plant canopy coverage (PCC) ratio is an important index of crop growth and development. Here, we present a tool, EasyPCC, for effective and accurate evaluation of the ground coverage ratio from a large number of images under variable field conditions. The core algorithm of EasyPCC is based on a pixel-based segmentation method using a decision-tree-based segmentation model (DTSM). EasyPCC was developed under the MATLAB^® and R languages; thus, it could be implemented in high-performance computing to handle large numbers of images following just a single model training process. This study used an experimental set of images from a paddy field to demonstrate EasyPCC, and to show the accuracy improvement possible by adjusting key points (e.g., outlier deletion and model retraining). The accuracy (R² = 0.99) of the calculated coverage ratio was validated against a corresponding benchmark dataset. The EasyPCC source code is released under GPL license with benchmark datasets of several different crop types for algorithm development and for evaluating ground coverage ratios. Full article

(This article belongs to the Section State-of-the-Art Sensors Technologies)

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16 pages, 15297 KiB

Open AccessArticle

Stroboscope Based Synchronization of Full Frame CCD Sensors

by Liang Shen^1,2,*, Xiaobing Feng^1,2, Yuan Zhang^1,2, Min Shi³, Dengming Zhu¹ and Zhaoqi Wang¹

¹ Virtual Reality Laboratory, Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190, China

² School of Computer and Control Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

³ School of Control and Computer Engineering, North China Electric Power University, Beijing 102206, China

Sensors 2017, 17(4), 799; https://doi.org/10.3390/s17040799 - 7 Apr 2017

Cited by 3 | Viewed by 5984

Abstract

The key obstacle to the use of consumer cameras in computer vision and computer graphics applications is the lack of synchronization hardware. We present a stroboscope based synchronization approach for the charge-coupled device (CCD) consumer cameras. The synchronization is realized by first aligning [...] Read more.

The key obstacle to the use of consumer cameras in computer vision and computer graphics applications is the lack of synchronization hardware. We present a stroboscope based synchronization approach for the charge-coupled device (CCD) consumer cameras. The synchronization is realized by first aligning the frames from different video sequences based on the smear dots of the stroboscope, and then matching the sequences using a hidden Markov model. Compared with current synchronized capture equipment, the proposed approach greatly reduces the cost by using inexpensive CCD cameras and one stroboscope. The results show that our method could reach a high accuracy much better than the frame-level synchronization of traditional software methods. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 303 KiB

Open AccessArticle

Square-Root Sigma-Point Information Consensus Filters for Distributed Nonlinear Estimation

by Guoliang Liu^* and Guohui Tian

School of Control Science and Engineering, Shandong University, Jinan 250061, China

Sensors 2017, 17(4), 800; https://doi.org/10.3390/s17040800 - 8 Apr 2017

Cited by 18 | Viewed by 4127

Abstract

This paper focuses on the convergence rate and numerical characteristics of the nonlinear information consensus filter for object tracking using a distributed sensor network. To avoid the Jacobian calculation, improve the numerical characteristic and achieve more accurate estimation results for nonlinear distributed estimation, [...] Read more.

This paper focuses on the convergence rate and numerical characteristics of the nonlinear information consensus filter for object tracking using a distributed sensor network. To avoid the Jacobian calculation, improve the numerical characteristic and achieve more accurate estimation results for nonlinear distributed estimation, we introduce square-root extensions of derivative-free information weighted consensus filters (IWCFs), which employ square-root versions of unscented transform, Stirling’s interpolation and cubature rules to linearize nonlinear models, respectively. In addition, to improve the convergence rate, we introduce the square-root dynamic hybrid consensus filters (DHCFs), which use an estimated factor to weight the information contributions and shows a faster convergence rate when the number of consensus iterations is limited. Finally, compared to the state of the art, the simulation shows that the proposed methods can improve the estimation results in the scenario of distributed camera networks. Full article

(This article belongs to the Section Sensor Networks)

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27 pages, 7111 KiB

Open AccessArticle

A Multi-Sensorial Simultaneous Localization and Mapping (SLAM) System for Low-Cost Micro Aerial Vehicles in GPS-Denied Environments

by Elena López^*, Sergio García, Rafael Barea

, Luis M. Bergasa

, Eduardo J. Molinos, Roberto Arroyo, Eduardo Romera and Samuel Pardo

Electronics Department, University of Alcalá, Campus Universitario, 28805 Alcalá de Henares, Spain

Sensors 2017, 17(4), 802; https://doi.org/10.3390/s17040802 - 8 Apr 2017

Cited by 76 | Viewed by 14959

Abstract

One of the main challenges of aerial robots navigation in indoor or GPS-denied environments is position estimation using only the available onboard sensors. This paper presents a Simultaneous Localization and Mapping (SLAM) system that remotely calculates the pose and environment map of different [...] Read more.

One of the main challenges of aerial robots navigation in indoor or GPS-denied environments is position estimation using only the available onboard sensors. This paper presents a Simultaneous Localization and Mapping (SLAM) system that remotely calculates the pose and environment map of different low-cost commercial aerial platforms, whose onboard computing capacity is usually limited. The proposed system adapts to the sensory configuration of the aerial robot, by integrating different state-of-the art SLAM methods based on vision, laser and/or inertial measurements using an Extended Kalman Filter (EKF). To do this, a minimum onboard sensory configuration is supposed, consisting of a monocular camera, an Inertial Measurement Unit (IMU) and an altimeter. It allows to improve the results of well-known monocular visual SLAM methods (LSD-SLAM and ORB-SLAM are tested and compared in this work) by solving scale ambiguity and providing additional information to the EKF. When payload and computational capabilities permit, a 2D laser sensor can be easily incorporated to the SLAM system, obtaining a local 2.5D map and a footprint estimation of the robot position that improves the 6D pose estimation through the EKF. We present some experimental results with two different commercial platforms, and validate the system by applying it to their position control. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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12 pages, 2416 KiB

Open AccessArticle

In Vitro Studies on a Microfluidic Sensor with Embedded Obstacles Using New Antibacterial Synthetic Compounds (1-TDPPO) Mixed Prop-2-en-1-one with Difluoro Phenyl

by Changhyun Roh^1,†, Jaewoong Lee^2,†, Mayank Kinger³ and Chankyu Kang^4,*

¹ Biotechnology Research Division, Advanced Radiation Technology Institute (ARTI), Korea Atomic Energy Research Institute (KAERI), 1266, Sinjeong-Dong, Jeongeup, Jeonbuk 580-185, Korea

² Department of Textile Engineering and Technology, Yeungnam University, 280 Daehak-ro, Gyeongsan, Gyeongbuk 38541, Korea

³ Department of Chemistry, Maharishi Markandeshwar University, Mullana, (Ambala) Haryana 133207, India

⁴ Ministry of Employment and Labor, Major Industrial Accident Prevention Center, 34 Yeosusandallo, Yeosu-Si, Jeonnam 59631, Korea

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 803; https://doi.org/10.3390/s17040803 - 8 Apr 2017

Cited by 3 | Viewed by 4401

Abstract

This paper describes the use of an analytical microfluidic sensor for accelerating chemo-repellent response and strong anti-bacterial 1-(Thien-2-yl)-3-(2, 6-difluoro phenyl) prop-2-en-1-one (1-TDPPO). The chemically-synthesized antimicrobial agent, which included prop-2-en-1-one and difluoro phenyl groups, was moving through an optically transparent polydimethylsiloxane (PDMS) microfluidic sensor [...] Read more.

This paper describes the use of an analytical microfluidic sensor for accelerating chemo-repellent response and strong anti-bacterial 1-(Thien-2-yl)-3-(2, 6-difluoro phenyl) prop-2-en-1-one (1-TDPPO). The chemically-synthesized antimicrobial agent, which included prop-2-en-1-one and difluoro phenyl groups, was moving through an optically transparent polydimethylsiloxane (PDMS) microfluidic sensor with circular obstacles arranged evenly. The response, growth and distribution of fluorescent labeling Pseudomonas aeruginosa PAO1 against the antimicrobial agent were monitored by confocal laser scanning microscope (CLSM). The microfluidic sensor along with 1-TDPPOin this study exhibits the following advantages: (i) Real-time chemo-repellent responses of cell dynamics; (ii) Rapid eradication of biofilm by embedded obstacles and powerful antibacterial agents, which significantly reduce the response time compared to classical methods; (iii) Minimal consumption of cells and antimicrobial agents; and (iv) Simplifying the process of the normalization of the fluorescence intensity and monitoring of biofilm by captured images and datasets. Full article

(This article belongs to the Section Biosensors)

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10 pages, 2384 KiB

Open AccessArticle

Synergetic Resonance Matching of a Microphone and a Photoacoustic Cell

by Joo Yong Sim

, Chang-Geun Ahn, Chul Huh, Kwang Hyo Chung, Eun-Ju Jeong and Bong Kyu Kim^*

Bio-Medical IT Convergence Research Department, Electronics and Telecommunications Research Institute, Daejeon 34129, Korea

Sensors 2017, 17(4), 804; https://doi.org/10.3390/s17040804 - 8 Apr 2017

Cited by 20 | Viewed by 5398

Abstract

We propose an approach to match the resonant characteristics of a photoacoustic cell with that of a microphone in order to enhance the signal-to-noise ratio in the photoacoustic sensor system. The synergetic resonance matching of a photoacoustic cell and a microphone was achieved [...] Read more.

We propose an approach to match the resonant characteristics of a photoacoustic cell with that of a microphone in order to enhance the signal-to-noise ratio in the photoacoustic sensor system. The synergetic resonance matching of a photoacoustic cell and a microphone was achieved by observing that photoacoustic cell resonance is merged with microphone resonance, in addition to conducting numerical and analytical simulations. Using this approach, we show that the signal-to-noise ratio was increased 3.5-fold from the optimized to non-optimized cell in the photoacoustic spectroscopy system. The present work is expected to have a broad impact on a number of applications, from improving weak photoacoustic signals in photoacoustic spectroscopy to ameliorating various sensors that use acoustic resonant filters. Full article

(This article belongs to the Section Chemical Sensors)

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18 pages, 7696 KiB

Open AccessArticle

A High Spatial Resolution Depth Sensing Method Based on Binocular Structured Light

by Huimin Yao¹, Chenyang Ge^1,2,*, Jianru Xue^1,3 and Nanning Zheng^1,2

¹ The Institute of Artificial Intelligence and Robotics, Xi’an Jiaotong University, Xi’an 710049, China

² The National Engineering Laboratory for Visual Information Processing and Applications, Xi’an Jiaotong University, Xi’an 710049, China

³ Shaanxi Provincial Key Laboratory of Digital Technology and Intelligent Systems, Xi’an 710049, China

Sensors 2017, 17(4), 805; https://doi.org/10.3390/s17040805 - 8 Apr 2017

Cited by 20 | Viewed by 6287

Abstract

Depth information has been used in many fields because of its low cost and easy availability, since the Microsoft Kinect was released. However, the Kinect and Kinect-like RGB-D sensors show limited performance in certain applications and place high demands on accuracy and robustness [...] Read more.

Depth information has been used in many fields because of its low cost and easy availability, since the Microsoft Kinect was released. However, the Kinect and Kinect-like RGB-D sensors show limited performance in certain applications and place high demands on accuracy and robustness of depth information. In this paper, we propose a depth sensing system that contains a laser projector similar to that used in the Kinect, and two infrared cameras located on both sides of the laser projector, to obtain higher spatial resolution depth information. We apply the block-matching algorithm to estimate the disparity. To improve the spatial resolution, we reduce the size of matching blocks, but smaller matching blocks generate lower matching precision. To address this problem, we combine two matching modes (binocular mode and monocular mode) in the disparity estimation process. Experimental results show that our method can obtain higher spatial resolution depth without loss of the quality of the range image, compared with the Kinect. Furthermore, our algorithm is implemented on a low-cost hardware platform, and the system can support the resolution of 1280 × 960, and up to a speed of 60 frames per second, for depth image sequences. Full article

(This article belongs to the Section Physical Sensors)

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28 pages, 9142 KiB

Open AccessArticle

Estimation of Antenna Pose in the Earth Frame Using Camera and IMU Data from Mobile Phones

by Zhen Wang

, Bingwen Jin and Weidong Geng^*

College of Computer Science and Technology, Zhejiang University, Zhejiang 310000, China

Sensors 2017, 17(4), 806; https://doi.org/10.3390/s17040806 - 8 Apr 2017

Cited by 4 | Viewed by 6030

Abstract

The poses of base station antennas play an important role in cellular network optimization. Existing methods of pose estimation are based on physical measurements performed either by tower climbers or using additional sensors attached to antennas. In this paper, we present a novel [...] Read more.

The poses of base station antennas play an important role in cellular network optimization. Existing methods of pose estimation are based on physical measurements performed either by tower climbers or using additional sensors attached to antennas. In this paper, we present a novel non-contact method of antenna pose measurement based on multi-view images of the antenna and inertial measurement unit (IMU) data captured by a mobile phone. Given a known 3D model of the antenna, we first estimate the antenna pose relative to the phone camera from the multi-view images and then employ the corresponding IMU data to transform the pose from the camera coordinate frame into the Earth coordinate frame. To enhance the resulting accuracy, we improve existing camera-IMU calibration models by introducing additional degrees of freedom between the IMU sensors and defining a new error metric based on both the downtilt and azimuth angles, instead of a unified rotational error metric, to refine the calibration. In comparison with existing camera-IMU calibration methods, our method achieves an improvement in azimuth accuracy of approximately 1.0 degree on average while maintaining the same level of downtilt accuracy. For the pose estimation in the camera coordinate frame, we propose an automatic method of initializing the optimization solver and generating bounding constraints on the resulting pose to achieve better accuracy. With this initialization, state-of-the-art visual pose estimation methods yield satisfactory results in more than 75% of cases when plugged into our pipeline, and our solution, which takes advantage of the constraints, achieves even lower estimation errors on the downtilt and azimuth angles, both on average (0.13 and 0.3 degrees lower, respectively) and in the worst case (0.15 and 7.3 degrees lower, respectively), according to an evaluation conducted on a dataset consisting of 65 groups of data. We show that both of our enhancements contribute to the performance improvement offered by the proposed estimation pipeline, which achieves downtilt and azimuth accuracies of respectively 0.47 and 5.6 degrees on average and 1.38 and 12.0 degrees in the worst case, thereby satisfying the accuracy requirements for network optimization in the telecommunication industry. Full article

(This article belongs to the Section Sensor Networks)

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23 pages, 3956 KiB

Open AccessArticle

Integrating Statistical Machine Learning in a Semantic Sensor Web for Proactive Monitoring and Control

by Jude Adekunle Adeleke^1,2,4,*

, Deshendran Moodley^2,3, Gavin Rens^1,2

and Aderemi Oluyinka Adewumi¹

¹ School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Westville Campus, University Road, Durban 3629, South Africa

² CSIR Meraka Centre for Artificial Intelligence Research (CAIR), Meiring Naude Road, Brummeria, Pretoria 0001, South Africa

³ Department of Computer Science, University of Cape Town, 18 University Avenue, Rondebosch 7701, South Africa

⁴ National Space Research and Development Agency, Obasanjo Space Centre, Airport Road, Abuja 900107, Nigeria

Sensors 2017, 17(4), 807; https://doi.org/10.3390/s17040807 - 9 Apr 2017

Cited by 26 | Viewed by 7312

Abstract

Proactive monitoring and control of our natural and built environments is important in various application scenarios. Semantic Sensor Web technologies have been well researched and used for environmental monitoring applications to expose sensor data for analysis in order to provide responsive actions in [...] Read more.

Proactive monitoring and control of our natural and built environments is important in various application scenarios. Semantic Sensor Web technologies have been well researched and used for environmental monitoring applications to expose sensor data for analysis in order to provide responsive actions in situations of interest. While these applications provide quick response to situations, to minimize their unwanted effects, research efforts are still necessary to provide techniques that can anticipate the future to support proactive control, such that unwanted situations can be averted altogether. This study integrates a statistical machine learning based predictive model in a Semantic Sensor Web using stream reasoning. The approach is evaluated in an indoor air quality monitoring case study. A sliding window approach that employs the Multilayer Perceptron model to predict short term PM

_{2.5}

pollution situations is integrated into the proactive monitoring and control framework. Results show that the proposed approach can effectively predict short term PM

_{2.5}

pollution situations: precision of up to 0.86 and sensitivity of up to 0.85 is achieved over half hour prediction horizons, making it possible for the system to warn occupants or even to autonomously avert the predicted pollution situations within the context of Semantic Sensor Web. Full article

(This article belongs to the Special Issue Sensors for Environmental Monitoring 2016)

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25 pages, 5240 KiB

Open AccessArticle

Coastal Areas Division and Coverage with Multiple UAVs for Remote Sensing

by Fotios Balampanis^*

, Iván Maza

and Aníbal Ollero

Robotics, Vision and Control Group, Universidad de Sevilla, Avda. de los Descubrimientos s/n, 41092 Seville, Spain

Sensors 2017, 17(4), 808; https://doi.org/10.3390/s17040808 - 9 Apr 2017

Cited by 60 | Viewed by 6904

Abstract

This paper tackles the problems of exact cell decomposition and partitioning of a coastal region for a team of heterogeneous Unmanned Aerial Vehicles (UAVs) with an approach that takes into account the field of view or sensing radius of the sensors on-board. An [...] Read more.

This paper tackles the problems of exact cell decomposition and partitioning of a coastal region for a team of heterogeneous Unmanned Aerial Vehicles (UAVs) with an approach that takes into account the field of view or sensing radius of the sensors on-board. An initial sensor-based exact cell decomposition of the area aids in the partitioning process, which is performed in two steps. In the first step, a growing regions algorithm performs an isotropic partitioning of the area based on the initial locations of the UAVs and their relative capabilities. Then, two novel algorithms are applied to compute an adjustment of this partitioning process, in order to solve deadlock situations that generate non-allocated regions and sub-areas above or below the relative capabilities of the UAVs. Finally, realistic simulations have been conducted for the evaluation of the proposed solution, and the obtained results show that these algorithms can compute valid and sound solutions in complex coastal region scenarios under different setups for the UAVs. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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8 pages, 5420 KiB

Open AccessArticle

A Novel Method of Identifying Paddy Seed Varieties

by Kuo-Yi Huang^* and Mao-Chien Chien

Department of Bio-Industrial Mechatronics Engineering, National Chung Hsing University, Tai-Chung 402, Taiwan

Sensors 2017, 17(4), 809; https://doi.org/10.3390/s17040809 - 9 Apr 2017

Cited by 31 | Viewed by 5871

Abstract

This paper presents a novel method for identifying three varieties (Taikong 9, Tainan 11, and Taikong 14) of foundation paddy seeds. Taikong 9, Tainan 11, and Taikong 14 paddy seeds are indistinguishable by inspectors during seed purity inspections. The proposed method uses image [...] Read more.

This paper presents a novel method for identifying three varieties (Taikong 9, Tainan 11, and Taikong 14) of foundation paddy seeds. Taikong 9, Tainan 11, and Taikong 14 paddy seeds are indistinguishable by inspectors during seed purity inspections. The proposed method uses image segmentation and a key point identification algorithm that can segment paddy seed images and extract seed features. A back propagation neural network was used to establish a classifier based on seven features that could classify the three paddy seed varieties. The classification accuracies of the resultant classifier for varieties Taikong 9, Tainan 11, and Taikong 14 were 92.68%, 97.35% and 96.57%, respectively. The experimental results indicated that the three paddy seeds can be differentiated efficiently using the developed system. Full article

(This article belongs to the Special Issue Innovative Sensing Control Scheme for Advanced Materials)

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17 pages, 2247 KiB

Open AccessArticle

Miniaturized FDDA and CMOS Based Potentiostat for Bio-Applications

by Elnaz Ghodsevali¹, Samuel Morneau-Gamache^1,2, Jessy Mathault¹

, Hamza Landari¹, Élodie Boisselier², Mounir Boukadoum³

, Benoit Gosselin⁴ and Amine Miled^1,*

¹ LABioTRON Bioeng. Research Laboratory, ECE Dept. Université Laval, Québec City, QC G1V 0A6, Canada

² Ophthalmology Department, Faculty of Medicine, Université Laval, Québec City, QC G1V 0A6, Canada

³ CoFaMic, Université du Québec à Montréal, Montreal, QC H2L 2C4, Canada

⁴ Biomedical Microsystems Laboratory, ECE Dept. Université Laval, Québec City, QC G1V 0A6, Canada

Sensors 2017, 17(4), 810; https://doi.org/10.3390/s17040810 - 10 Apr 2017

Cited by 11 | Viewed by 7614

Abstract

A novel fully differential difference CMOS potentiostat suitable for neurotransmitter sensing is presented. The described architecture relies on a fully differential difference amplifier (FDDA) circuit to detect a wide range of reduction-oxidation currents, while exhibiting low-power consumption and low-noise operation. This is made [...] Read more.

A novel fully differential difference CMOS potentiostat suitable for neurotransmitter sensing is presented. The described architecture relies on a fully differential difference amplifier (FDDA) circuit to detect a wide range of reduction-oxidation currents, while exhibiting low-power consumption and low-noise operation. This is made possible thanks to the fully differential feature of the FDDA, which allows to increase the source voltage swing without the need for additional dedicated circuitry. The FDDA also reduces the number of amplifiers and passive elements in the potentiostat design, which lowers the overall power consumption and noise. The proposed potentiostat was fabricated in 0.18 µm CMOS, with 1.8 V supply voltage. The device achieved 5 µA sensitivity and 0.99 linearity. The input-referred noise was 6.9 µV

_{rms}

and the flicker noise was negligible. The total power consumption was under 55 µW. The complete system was assembled on a 20 mm × 20 mm platform that includes the potentiostat chip, the electrode terminals and an instrumentation amplifier for redox current buffering, once converted to a voltage by a series resistor. the chip dimensions were 1 mm × 0.5 mm and the other PCB components were off-chip resistors, capacitors and amplifiers for data acquisition. The system was successfully tested with ferricyanide, a stable electroactive compound, and validated with dopamine, a popular neurotransmitter. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Canada 2017)

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8 pages, 1437 KiB

Open AccessArticle

Detecting Electron Transport of Amino Acids by Using Conductance Measurement

by Wei-Qiong Li¹, Bing Huang¹, Miao-Ling Huang¹, Lin-Lu Peng¹, Ze-Wen Hong¹, Ju-Fang Zheng¹, Wen-Bo Chen², Jian-Feng Li³ and Xiao-Shun Zhou^1,*

¹ Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China

² Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, China

³ State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China

Sensors 2017, 17(4), 811; https://doi.org/10.3390/s17040811 - 10 Apr 2017

Cited by 15 | Viewed by 6540

Abstract

The single molecular conductance of amino acids was measured by a scanning tunneling microscope (STM) break junction. Conductance measurement of alanine gives out two conductance values at 10^−1.85 G₀ (1095 nS) and 10^−3.7 G₀ (15.5 nS), while similar conductance [...] Read more.

The single molecular conductance of amino acids was measured by a scanning tunneling microscope (STM) break junction. Conductance measurement of alanine gives out two conductance values at 10^−1.85 G₀ (1095 nS) and 10^−3.7 G₀ (15.5 nS), while similar conductance values are also observed for aspartic acid and glutamic acid, which have one more carboxylic acid group compared with alanine. This may show that the backbone of NH₂–C–COOH is the primary means of electron transport in the molecular junction of aspartic acid and glutamic acid. However, NH₂–C–COOH is not the primary means of electron transport in the methionine junction, which may be caused by the strong interaction of the Au–SMe (methyl sulfide) bond for the methionine junction. The current work reveals the important role of the anchoring group in the electron transport in different amino acids junctions. Full article

(This article belongs to the Section Chemical Sensors)

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15 pages, 1600 KiB

Open AccessArticle

Fusing Bluetooth Beacon Data with Wi-Fi Radiomaps for Improved Indoor Localization

by Loizos Kanaris^1,*,†, Akis Kokkinis^1,†

, Antonio Liotta^1,†

and Stavros Stavrou^2,†

¹ Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands

² Faculty of Pure and Applied Sciences, Open University of Cyprus, Nicosia 2252, Cyprus

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 812; https://doi.org/10.3390/s17040812 - 10 Apr 2017

Cited by 74 | Viewed by 10322

Abstract

Indoor user localization and tracking are instrumental to a broad range of services and applications in the Internet of Things (IoT) and particularly in Body Sensor Networks (BSN) and Ambient Assisted Living (AAL) scenarios. Due to the widespread availability of IEEE 802.11, many [...] Read more.

Indoor user localization and tracking are instrumental to a broad range of services and applications in the Internet of Things (IoT) and particularly in Body Sensor Networks (BSN) and Ambient Assisted Living (AAL) scenarios. Due to the widespread availability of IEEE 802.11, many localization platforms have been proposed, based on the Wi-Fi Received Signal Strength (RSS) indicator, using algorithms such as K-Nearest Neighbour (KNN), Maximum A Posteriori (MAP) and Minimum Mean Square Error (MMSE). In this paper, we introduce a hybrid method that combines the simplicity (and low cost) of Bluetooth Low Energy (BLE) and the popular 802.11 infrastructure, to improve the accuracy of indoor localization platforms. Building on KNN, we propose a new positioning algorithm (dubbed i-KNN) which is able to filter the initial fingerprint dataset (i.e., the radiomap), after considering the proximity of RSS fingerprints with respect to the BLE devices. In this way, i-KNN provides an optimised small subset of possible user locations, based on which it finally estimates the user position. The proposed methodology achieves fast positioning estimation due to the utilization of a fragment of the initial fingerprint dataset, while at the same time improves positioning accuracy by minimizing any calculation errors. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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25 pages, 1853 KiB

Open AccessArticle

Combining DCQGMP-Based Sparse Decomposition and MPDR Beamformer for Multi-Type Interferences Mitigation for GNSS Receivers

by Qiang Guo and Liangang Qi^*

College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China

Sensors 2017, 17(4), 813; https://doi.org/10.3390/s17040813 - 10 Apr 2017

Cited by 3 | Viewed by 4066

Abstract

In the coexistence of multiple types of interfering signals, the performance of interference suppression methods based on time and frequency domains is degraded seriously, and the technique using an antenna array requires a large enough size and huge hardware costs. To combat multi-type [...] Read more.

In the coexistence of multiple types of interfering signals, the performance of interference suppression methods based on time and frequency domains is degraded seriously, and the technique using an antenna array requires a large enough size and huge hardware costs. To combat multi-type interferences better for GNSS receivers, this paper proposes a cascaded multi-type interferences mitigation method combining improved double chain quantum genetic matching pursuit (DCQGMP)-based sparse decomposition and an MPDR beamformer. The key idea behind the proposed method is that the multiple types of interfering signals can be excised by taking advantage of their sparse features in different domains. In the first stage, the single-tone (multi-tone) and linear chirp interfering signals are canceled by sparse decomposition according to their sparsity in the over-complete dictionary. In order to improve the timeliness of matching pursuit (MP)-based sparse decomposition, a DCQGMP is introduced by combining an improved double chain quantum genetic algorithm (DCQGA) and the MP algorithm, and the DCQGMP algorithm is extended to handle the multi-channel signals according to the correlation among the signals in different channels. In the second stage, the minimum power distortionless response (MPDR) beamformer is utilized to nullify the residuary interferences (e.g., wideband Gaussian noise interferences). Several simulation results show that the proposed method can not only improve the interference mitigation degree of freedom (DoF) of the array antenna, but also effectively deal with the interference arriving from the same direction with the GNSS signal, which can be sparse represented in the over-complete dictionary. Moreover, it does not bring serious distortions into the navigation signal. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 6501 KiB

Open AccessArticle

Sub-Pixel Extraction of Laser Stripe Center Using an Improved Gray-Gravity Method ^†

by Yuehua Li^†, Jingbo Zhou^*,†, Fengshan Huang^† and Lijian Liu^†

¹ School of Mechanical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China

^† This paper is an extended version of our paper published in the 10th International Conference on Sensing Technology (ICST), Nanjing, China, 11–13 November 2016.

Sensors 2017, 17(4), 814; https://doi.org/10.3390/s17040814 - 10 Apr 2017

Cited by 118 | Viewed by 10846

Abstract

Laser stripe center extraction is a key step for the profile measurement of line structured light sensors (LSLS). To accurately obtain the center coordinates at sub-pixel level, an improved gray-gravity method (IGGM) was proposed. Firstly, the center points of the stripe were computed [...] Read more.

Laser stripe center extraction is a key step for the profile measurement of line structured light sensors (LSLS). To accurately obtain the center coordinates at sub-pixel level, an improved gray-gravity method (IGGM) was proposed. Firstly, the center points of the stripe were computed using the gray-gravity method (GGM) for all columns of the image. By fitting these points using the moving least squares algorithm, the tangential vector, the normal vector and the radius of curvature can be robustly obtained. One rectangular region could be defined around each of the center points. Its two sides that are parallel to the tangential vector could alter their lengths according to the radius of the curvature. After that, the coordinate for each center point was recalculated within the rectangular region and in the direction of the normal vector. The center uncertainty was also analyzed based on the Monte Carlo method. The obtained experimental results indicate that the IGGM is suitable for both the smooth stripes and the ones with sharp corners. The high accuracy center points can be obtained at a relatively low computation cost. The measured results of the stairs and the screw surface further demonstrate the effectiveness of the method. Full article

(This article belongs to the Special Issue Intelligent Sensing and Information Mining—Selected Papers from the 10th International Conference on Sensing Technology)

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14 pages, 7487 KiB

Open AccessArticle

Efficient Streaming Mass Spatio-Temporal Vehicle Data Access in Urban Sensor Networks Based on Apache Storm

by Lianjie Zhou¹

, Nengcheng Chen^1,2,*

and Zeqiang Chen²

¹ State Key Laboratory of Information Engineering in Surveying, Mapping, and Remote Sensing, Wuhan University, Luoyu Road 129, Wuhan 430079, China

² Collaborative Innovation Center of Geospatial Technology, 129 Luoyu Road, Wuhan 430079, China

Sensors 2017, 17(4), 815; https://doi.org/10.3390/s17040815 - 10 Apr 2017

Cited by 13 | Viewed by 5894

Abstract

The efficient data access of streaming vehicle data is the foundation of analyzing, using and mining vehicle data in smart cities, which is an approach to understand traffic environments. However, the number of vehicles in urban cities has grown rapidly, reaching hundreds of [...] Read more.

The efficient data access of streaming vehicle data is the foundation of analyzing, using and mining vehicle data in smart cities, which is an approach to understand traffic environments. However, the number of vehicles in urban cities has grown rapidly, reaching hundreds of thousands in number. Accessing the mass streaming data of vehicles is hard and takes a long time due to limited computation capability and backward modes. We propose an efficient streaming spatio-temporal data access based on Apache Storm (ESDAS) to achieve real-time streaming data access and data cleaning. As a popular streaming data processing tool, Apache Storm can be applied to streaming mass data access and real time data cleaning. By designing the Spout/bolt workflow of topology in ESDAS and by developing the speeding bolt and other bolts, Apache Storm can achieve the prospective aim. In our experiments, Taiyuan BeiDou bus location data is selected as the mass spatio-temporal data source. In the experiments, the data access results with different bolts are shown in map form, and the filtered buses’ aggregation forms are different. In terms of performance evaluation, the consumption time in ESDAS for ten thousand records per second for a speeding bolt is approximately 300 milliseconds, and that for MongoDB is approximately 1300 milliseconds. The efficiency of ESDAS is approximately three times higher than that of MongoDB. Full article

(This article belongs to the Section Sensor Networks)

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10 pages, 3394 KiB

Open AccessArticle

Implementation of a Cross-Layer Sensing Medium-Access Control Scheme

by Yishan Su^1,2, Xiaomei Fu^1,2,*

, Guangyao Han², Naishen Xu² and Zhigang Jin²

¹ School of Marine Science and Technology, Tianjin University, Tianjin 300072, China

² School of Electrical Automation and Information Engineering, Tianjin University, Tianjin 300072, China

Sensors 2017, 17(4), 816; https://doi.org/10.3390/s17040816 - 10 Apr 2017

Cited by 7 | Viewed by 3504

Abstract

In this paper, compressed sensing (CS) theory is utilized in a medium-access control (MAC) scheme for wireless sensor networks (WSNs). We propose a new, cross-layer compressed sensing medium-access control (CL CS-MAC) scheme, combining the physical layer and data link layer, where the wireless [...] Read more.

In this paper, compressed sensing (CS) theory is utilized in a medium-access control (MAC) scheme for wireless sensor networks (WSNs). We propose a new, cross-layer compressed sensing medium-access control (CL CS-MAC) scheme, combining the physical layer and data link layer, where the wireless transmission in physical layer is considered as a compress process of requested packets in a data link layer according to compressed sensing (CS) theory. We first introduced using compressive complex requests to identify the exact active sensor nodes, which makes the scheme more efficient. Moreover, because the reconstruction process is executed in a complex field of a physical layer, where no bit and frame synchronizations are needed, the asynchronous and random requests scheme can be implemented without synchronization payload. We set up a testbed based on software-defined radio (SDR) to implement the proposed CL CS-MAC scheme practically and to demonstrate the validation. For large-scale WSNs, the simulation results show that the proposed CL CS-MAC scheme provides higher throughput and robustness than the carrier sense multiple access (CSMA) and compressed sensing medium-access control (CS-MAC) schemes. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 1908 KiB

Open AccessArticle

A Quadrilateral Geometry Classification Method and Device for Femtocell Positioning Networks

by Jeich Mar^1,2,*, Tsung Yu Chang¹ and Yu Jie Wang¹

¹ Department of Communications Engineering, Yuan-Ze University, Taoyuan 320, Taiwan

² Communication Research Center, Yuan-Ze University, Taoyuan 320, Taiwan

Sensors 2017, 17(4), 817; https://doi.org/10.3390/s17040817 - 10 Apr 2017

Cited by 2 | Viewed by 3885

Abstract

This article proposes a normalization multi-layer perception (NMLP) geometry classifier to autonomously determine the optimal four femtocell evolved Node Bs (FeNBs), which can use time difference of arrival (TDOA) to measure the location of the macrocell user equipment (MUE) with the lowest GDOP [...] Read more.

This article proposes a normalization multi-layer perception (NMLP) geometry classifier to autonomously determine the optimal four femtocell evolved Node Bs (FeNBs), which can use time difference of arrival (TDOA) to measure the location of the macrocell user equipment (MUE) with the lowest GDOP value. The iterative geometry training (IGT) algorithm is designed to obtain the training data for the NMLP geometry classifier. The architecture of the proposed NMLP geometry classifier is realized in the server of the cloud computing platform, to identify the optimal geometry disposition of four FeNBs for positioning the MUE located between two buildings. Six by six neurons are chosen for two hidden layers, in order to shorten the convergent time. The feasibility of the proposed method is demonstrated by means of numerical simulations. In addition, the simulation results also show that the proposed method is particularly suitable for the application of the MUE positioning with a huge number of FeNBs. Finally, three quadrilateral optimum geometry disposition decision criteria are analyzed for the validation of the simulation results. Full article

(This article belongs to the Special Issue Innovative Sensing Control Scheme for Advanced Materials)

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16 pages, 2637 KiB

Open AccessArticle

Learning Traffic as Images: A Deep Convolutional Neural Network for Large-Scale Transportation Network Speed Prediction

by Xiaolei Ma¹, Zhuang Dai¹, Zhengbing He², Jihui Ma^2,*, Yong Wang³ and Yunpeng Wang¹

¹ School of Transportation Science and Engineering, Beijing Key Laboratory for Cooperative Vehicle Infrastructure System and Safety Control, Beihang University, Beijing 100191, China

² School of Traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China

³ School of Economics and Management, Chongqing Jiaotong University, Chongqing 400074, China

Sensors 2017, 17(4), 818; https://doi.org/10.3390/s17040818 - 10 Apr 2017

Cited by 1216 | Viewed by 33142

Abstract

This paper proposes a convolutional neural network (CNN)-based method that learns traffic as images and predicts large-scale, network-wide traffic speed with a high accuracy. Spatiotemporal traffic dynamics are converted to images describing the time and space relations of traffic flow via a two-dimensional [...] Read more.

This paper proposes a convolutional neural network (CNN)-based method that learns traffic as images and predicts large-scale, network-wide traffic speed with a high accuracy. Spatiotemporal traffic dynamics are converted to images describing the time and space relations of traffic flow via a two-dimensional time-space matrix. A CNN is applied to the image following two consecutive steps: abstract traffic feature extraction and network-wide traffic speed prediction. The effectiveness of the proposed method is evaluated by taking two real-world transportation networks, the second ring road and north-east transportation network in Beijing, as examples, and comparing the method with four prevailing algorithms, namely, ordinary least squares, k-nearest neighbors, artificial neural network, and random forest, and three deep learning architectures, namely, stacked autoencoder, recurrent neural network, and long-short-term memory network. The results show that the proposed method outperforms other algorithms by an average accuracy improvement of 42.91% within an acceptable execution time. The CNN can train the model in a reasonable time and, thus, is suitable for large-scale transportation networks. Full article

(This article belongs to the Special Issue Sensors for Transportation)

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14 pages, 3614 KiB

Open AccessArticle

Comparison between a Direct-Flow SPR Immunosensor for Ampicillin and a Competitive Conventional Amperometric Device: Analytical Features and Possible Applications to Real Samples

by Mauro Tomassetti^1,*

, Giovanni Merola¹, Elisabetta Martini¹, Luigi Campanella¹, Gabriella Sanzò², Gabriele Favero²

and Franco Mazzei²

¹ Department of Chemistry, “Sapienza” University of Rome, P.le A. Moro, 5, 00185 Rome, Italy

² Department of Chemistry and Pharmacy Technology, “Sapienza” University of Rome, P.le A. Moro, 5, 00185 Rome, Italy

Sensors 2017, 17(4), 819; https://doi.org/10.3390/s17040819 - 10 Apr 2017

Cited by 12 | Viewed by 5758

Abstract

In this research, we developed a direct-flow surface plasmon resonance (SPR) immunosensor for ampicillin to perform direct, simple, and fast measurements of this important antibiotic. In order to better evaluate the performance, it was compared with a conventional amperometric immunosensor, working with a [...] Read more.

In this research, we developed a direct-flow surface plasmon resonance (SPR) immunosensor for ampicillin to perform direct, simple, and fast measurements of this important antibiotic. In order to better evaluate the performance, it was compared with a conventional amperometric immunosensor, working with a competitive format with the aim of finding out experimental real advantages and disadvantages of two respective methods. Results showed that certain analytical features of the new SPR immunodevice, such as the lower limit of detection (LOD) value and the width of the linear range, are poorer than those of a conventional amperometric immunosensor, which adversely affects the application to samples such as natural waters. On the other hand, the SPR immunosensor was more selective to ampicillin, and measurements were more easily and quickly attained compared to those performed with the conventional competitive immunosensor. Full article

(This article belongs to the Special Issue Electrochemical Immunosensors)

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17 pages, 8842 KiB

Open AccessArticle

Design and Experimental Study of a Current Transformer with a Stacked PCB Based on B-Dot

by Jingang Wang¹, Diancheng Si^1,*, Tian Tian² and Ran Ren²

¹ State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044, China

² Chongying Electric Power Design Institute, Chongying 401121, China

Sensors 2017, 17(4), 820; https://doi.org/10.3390/s17040820 - 10 Apr 2017

Cited by 14 | Viewed by 6861

Abstract

An electronic current transformer with a B-dot sensor is proposed in this study. The B-dot sensor can realize the current measurement of the transmission line in a non-contact way in accordance with the principle of magnetic field coupling. The multiple electrodes series-opposing structure [...] Read more.

An electronic current transformer with a B-dot sensor is proposed in this study. The B-dot sensor can realize the current measurement of the transmission line in a non-contact way in accordance with the principle of magnetic field coupling. The multiple electrodes series-opposing structure is applied together with differential input structures and active integrating circuits, which can allow the sensor to operate in differential mode. Maxwell software is adopted to model and simulate the sensor. Optimization of the sensor structural parameters is conducted through finite-element simulation. A test platform is built to conduct the steady-state characteristic, on-off operation, and linearity tests for the designed current transformer under the power-frequency current. As shown by the test results, in contrast with traditional electromagnetic CT, the designed current transformer can achieve high accuracy and good phase-frequency; its linearity is also very good at different distances from the wire. The proposed current transformer provides a new method for electricity larceny prevention and on-line monitoring of the power grid in an electric system, thereby satisfying the development demands of the smart power grid. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 4920 KiB

Open AccessArticle

Dynamic Synchronous Capture Algorithm for an Electromagnetic Flowmeter

by Yong-Yi Fanjiang^*

and Shih-Wei Lu

Department of Computer Science and Information Engineering, Fu Jen Catholic University, New Taipei 24205, Taiwan

Sensors 2017, 17(4), 821; https://doi.org/10.3390/s17040821 - 10 Apr 2017

Cited by 12 | Viewed by 4699

Abstract

This paper proposes a dynamic synchronous capture (DSC) algorithm to calculate the flow rate for an electromagnetic flowmeter. The characteristics of the DSC algorithm can accurately calculate the flow rate signal and efficiently convert an analog signal to upgrade the execution performance of [...] Read more.

This paper proposes a dynamic synchronous capture (DSC) algorithm to calculate the flow rate for an electromagnetic flowmeter. The characteristics of the DSC algorithm can accurately calculate the flow rate signal and efficiently convert an analog signal to upgrade the execution performance of a microcontroller unit (MCU). Furthermore, it can reduce interference from abnormal noise. It is extremely steady and independent of fluctuations in the flow measurement. Moreover, it can calculate the current flow rate signal immediately (m/s). The DSC algorithm can be applied to the current general MCU firmware platform without using DSP (Digital Signal Processing) or a high-speed and high-end MCU platform, and signal amplification by hardware reduces the demand for ADC accuracy, which reduces the cost. Full article

(This article belongs to the Special Issue Magnetic Sensors and Their Applications)

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15 pages, 12058 KiB

Open AccessArticle

Hazards in Motion: Development of Mobile Geofences for Use in Logging Safety

by Eloise G. Zimbelman^*

, Robert F. Keefe

, Eva K. Strand, Crystal A. Kolden

and Ann M. Wempe

Department of Forest, Rangeland and Fire Sciences, University of Idaho, 875 Perimeter Drive, Moscow, ID 83844-1133, USA

Sensors 2017, 17(4), 822; https://doi.org/10.3390/s17040822 - 10 Apr 2017

Cited by 33 | Viewed by 8590

Abstract

Logging is one of the most hazardous occupations in the United States. Real-time positioning that uses global navigation satellite system (GNSS) technology paired with radio frequency transmission (GNSS-RF) has the potential to reduce fatal and non-fatal accidents on logging operations through the use [...] Read more.

Logging is one of the most hazardous occupations in the United States. Real-time positioning that uses global navigation satellite system (GNSS) technology paired with radio frequency transmission (GNSS-RF) has the potential to reduce fatal and non-fatal accidents on logging operations through the use of geofences that define safe work areas. Until recently, most geofences have been static boundaries. The aim of this study was to evaluate factors affecting mobile geofence accuracy in order to determine whether virtual safety zones around moving ground workers or equipment are a viable option for improving situational awareness on active timber sales. We evaluated the effects of walking pace, transmission interval, geofence radius, and intersection angle on geofence alert delay using a replicated field experiment. Simulation was then used to validate field results and calculate the proportion of GNSS error bearings resulting in early alerts. The interaction of geofence radius and intersection angle affected safety geofence alert delay in the field experiment. The most inaccurate alerts were negative, representing early warning. The magnitude of this effect was largest at the greatest intersection angles. Simulation analysis supported these field results and also showed that larger GNSS error corresponded to greater variability in alert delay. Increasing intersection angle resulted in a larger proportion of directional GNSS error that triggered incorrect, early warnings. Because the accuracy of geofence alerts varied greatly depending on GNSS error and angle of approach, geofencing for occupational safety is most appropriate for general situational awareness unless real-time correction methods to improve accuracy or higher quality GNSS-RF transponders are used. Full article

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9 pages, 4166 KiB

Open AccessArticle

Novel Compensation Scheme for the Modulation Gain to Suppress the Quantization-Induced Bias in a Fiber Optic Gyroscope

by Xiong Pan

, Pengcheng Liu^*

, Shaobo Zhang, Jing Jin and Ningfang Song

Institute of Opto-electronics Technology, School of Instrument Science and Opto-electronics Engineering, Beihang University, Beijing 100191, China

Sensors 2017, 17(4), 823; https://doi.org/10.3390/s17040823 - 10 Apr 2017

Cited by 7 | Viewed by 4604

Abstract

A novel digital compensation scheme is demonstrated to control the gain of the modulation chain and suppress the influence of quantization error on bias. The error produced by the quantization multiplied by the scaling factor is theoretically analyzed. Simulations indicate that the quantization [...] Read more.

A novel digital compensation scheme is demonstrated to control the gain of the modulation chain and suppress the influence of quantization error on bias. The error produced by the quantization multiplied by the scaling factor is theoretically analyzed. Simulations indicate that the quantization error varies with the input angular velocity and temperature, which is verified by experiments. By switching the integration and compression operations in the modulation chain, this quantization error is reduced, while automatic reset of the digital phase ramp register is achieved. We test the scheme in a fiber optic gyroscope. The test results reveal that the quantization-induced bias is suppressed and the residual bias is two times less than the desired accuracy with data accumulated over one-second sample interval. The scheme is a feasible method to miniaturize fiber optic gyroscope using a totally digital circuit for compensation of the modulation gain. Full article

(This article belongs to the Special Issue Laser Sensors for Displacement, Distance, Flow, Velocity and Vibrations Measurements)

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15 pages, 792 KiB

Open AccessArticle

A Robust Diffusion Estimation Algorithm with Self-Adjusting Step-Size in WSNs

by Xiaodan Shao^1,2, Feng Chen^1,*,†, Qing Ye² and Shukai Duan²

¹ College of Electronic and Information Engineering, School of Mathematics and Statistics, Southwest University, and Key Laboratory of Nonlinear Circuits and Intelligent Information Processing, Chongqing 400715, China

² College of Electronic and Information Engineering, Southwest University, Chongqing 400715, China

^† Current address: Key Laboratory of Nonlinear Circuits and Intelligent Information Processing, No.2, Tiansheng Road, Beibei District, Chongqing 400715, China

Sensors 2017, 17(4), 824; https://doi.org/10.3390/s17040824 - 10 Apr 2017

Cited by 11 | Viewed by 3939

Abstract

In wireless sensor networks (WSNs), each sensor node can estimate the global parameter from the local data in a distributed manner. This paper proposed a robust diffusion estimation algorithm based on a minimum error entropy criterion with a self-adjusting step-size, which are referred [...] Read more.

In wireless sensor networks (WSNs), each sensor node can estimate the global parameter from the local data in a distributed manner. This paper proposed a robust diffusion estimation algorithm based on a minimum error entropy criterion with a self-adjusting step-size, which are referred to as the diffusion MEE-SAS (DMEE-SAS) algorithm. The DMEE-SAS algorithm has a fast speed of convergence and is robust against non-Gaussian noise in the measurements. The detailed performance analysis of the DMEE-SAS algorithm is performed. By combining the DMEE-SAS algorithm with the diffusion minimum error entropy (DMEE) algorithm, an Improving DMEE-SAS algorithm is proposed for a non-stationary environment where tracking is very important. The Improving DMEE-SAS algorithm can avoid insensitivity of the DMEE-SAS algorithm due to the small effective step-size near the optimal estimator and obtain a fast convergence speed. Numerical simulations are given to verify the effectiveness and advantages of these proposed algorithms. Full article

(This article belongs to the Section Sensor Networks)

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29 pages, 5644 KiB

Open AccessArticle

Inertial Sensor-Based Robust Gait Analysis in Non-Hospital Settings for Neurological Disorders

by Can Tunca^1,*

, Nezihe Pehlivan¹, Nağme Ak², Bert Arnrich¹, Gülüstü Salur^2,† and Cem Ersoy¹

¹ Department of Computer Engineering, Computer Networks Research Laboratory (NETLAB), Bogazici University, 34342 Istanbul, Turkey

² 65+ Elder Rights Association, 34337 Istanbul, Turkey

^† Current Address: Movement Disorders & Dementia Clinic, 34337 Istanbul, Turkey.

Sensors 2017, 17(4), 825; https://doi.org/10.3390/s17040825 - 11 Apr 2017

Cited by 122 | Viewed by 22511

Abstract

The gold standards for gait analysis are instrumented walkways and marker-based motion capture systems, which require costly infrastructure and are only available in hospitals and specialized gait clinics. Even though the completeness and the accuracy of these systems are unquestionable, a mobile and [...] Read more.

The gold standards for gait analysis are instrumented walkways and marker-based motion capture systems, which require costly infrastructure and are only available in hospitals and specialized gait clinics. Even though the completeness and the accuracy of these systems are unquestionable, a mobile and pervasive gait analysis alternative suitable for non-hospital settings is a clinical necessity. Using inertial sensors for gait analysis has been well explored in the literature with promising results. However, the majority of the existing work does not consider realistic conditions where data collection and sensor placement imperfections are imminent. Moreover, some of the underlying assumptions of the existing work are not compatible with pathological gait, decreasing the accuracy. To overcome these challenges, we propose a foot-mounted inertial sensor-based gait analysis system that extends the well-established zero-velocity update and Kalman filtering methodology. Our system copes with various cases of data collection difficulties and relaxes some of the assumptions invalid for pathological gait (e.g., the assumption of observing a heel strike during a gait cycle). The system is able to extract a rich set of standard gait metrics, including stride length, cadence, cycle time, stance time, swing time, stance ratio, speed, maximum/minimum clearance and turning rate. We validated the spatio-temporal accuracy of the proposed system by comparing the stride length and swing time output with an IR depth-camera-based reference system on a dataset comprised of 22 subjects. Furthermore, to highlight the clinical applicability of the system, we present a clinical discussion of the extracted metrics on a disjoint dataset of 17 subjects with various neurological conditions. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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22 pages, 2415 KiB

Open AccessArticle

Energy Efficiency in Public Buildings through Context-Aware Social Computing

by Óscar García^*, Ricardo S. Alonso

, Javier Prieto

and Juan M. Corchado

BISITE Research Group, Edificio I+D+I, University of Salamanca, 37007 Salamanca, Spain

Sensors 2017, 17(4), 826; https://doi.org/10.3390/s17040826 - 11 Apr 2017

Cited by 57 | Viewed by 9051

Abstract

The challenge of promoting behavioral changes in users that leads to energy savings in public buildings has become a complex task requiring the involvement of multiple technologies. Wireless sensor networks have a great potential for the development of tools, such as serious games, [...] Read more.

The challenge of promoting behavioral changes in users that leads to energy savings in public buildings has become a complex task requiring the involvement of multiple technologies. Wireless sensor networks have a great potential for the development of tools, such as serious games, that encourage acquiring good energy and healthy habits among users in the workplace. This paper presents the development of a serious game using CAFCLA, a framework that allows for integrating multiple technologies, which provide both context-awareness and social computing. Game development has shown that the data provided by sensor networks encourage users to reduce energy consumption in their workplace and that social interactions and competitiveness allow for accelerating the achievement of good results and behavioral changes that favor energy savings. Full article

(This article belongs to the Special Issue Context Aware Environments and Applications)

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28 pages, 4193 KiB

Open AccessArticle

A Waist-Worn Inertial Measurement Unit for Long-Term Monitoring of Parkinson’s Disease Patients

by Daniel Rodríguez-Martín^1,*,†, Carlos Pérez-López^1,†, Albert Samà¹, Andreu Català¹, Joan Manuel Moreno Arostegui¹, Joan Cabestany¹, Berta Mestre², Sheila Alcaine², Anna Prats², María De la Cruz Crespo² and Àngels Bayés²

¹ Technical Research Centre for Dependency Care and Autonomous Living—CETPD, Universitat Politècnica de Catalunya—BarcelonaTech, Rambla de l’Exposició 59-69, Vilanova i la Geltrú, 08800 Barcelona, Spain

² Unidad de Parkinson y Trastornos del Movimiento (UParkinson), Passeig Bonanova 26, 08022 Barcelona, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 827; https://doi.org/10.3390/s17040827 - 11 Apr 2017

Cited by 41 | Viewed by 9045

Abstract

Inertial measurement units (IMUs) are devices used, among other fields, in health applications, since they are light, small and effective. More concretely, IMUs have been demonstrated to be useful in the monitoring of motor symptoms of Parkinson’s disease (PD). In this sense, most [...] Read more.

Inertial measurement units (IMUs) are devices used, among other fields, in health applications, since they are light, small and effective. More concretely, IMUs have been demonstrated to be useful in the monitoring of motor symptoms of Parkinson’s disease (PD). In this sense, most of previous works have attempted to assess PD symptoms in controlled environments or short tests. This paper presents the design of an IMU, called 9 × 3, that aims to assess PD symptoms, enabling the possibility to perform a map of patients’ symptoms at their homes during long periods. The device is able to acquire and store raw inertial data for artificial intelligence algorithmic training purposes. Furthermore, the presented IMU enables the real-time execution of the developed and embedded learning models. Results show the great flexibility of the 9 × 3, storing inertial information and algorithm outputs, sending messages to external devices and being able to detect freezing of gait and bradykinetic gait. Results obtained in 12 patients exhibit a sensitivity and specificity over 80%. Additionally, the system enables working 23 days (at waking hours) with a 1200 mAh battery and a sampling rate of 50 Hz, opening up the possibility to be used for other applications like wellbeing and sports. Full article

(This article belongs to the Special Issue Sensors for Ambient Assisted Living, Ubiquitous and Mobile Health)

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14 pages, 5106 KiB

Open AccessArticle

A Low-Cost Environmental Monitoring System: How to Prevent Systematic Errors in the Design Phase through the Combined Use of Additive Manufacturing and Thermographic Techniques

by Francesco Salamone^*

, Ludovico Danza

, Italo Meroni and Maria Cristina Pollastro

ITC-CNR, Construction Technologies Institute, National Research Council of Italy, Via Lombardia, 49, 20098 San Giuliano Milanese (MI), Italy

Sensors 2017, 17(4), 828; https://doi.org/10.3390/s17040828 - 11 Apr 2017

Cited by 45 | Viewed by 10300

Abstract

nEMoS (nano Environmental Monitoring System) is a 3D-printed device built following the Do-It-Yourself (DIY) approach. It can be connected to the web and it can be used to assess indoor environmental quality (IEQ). It is built using some low-cost sensors connected to an [...] Read more.

nEMoS (nano Environmental Monitoring System) is a 3D-printed device built following the Do-It-Yourself (DIY) approach. It can be connected to the web and it can be used to assess indoor environmental quality (IEQ). It is built using some low-cost sensors connected to an Arduino microcontroller board. The device is assembled in a small-sized case and both thermohygrometric sensors used to measure the air temperature and relative humidity, and the globe thermometer used to measure the radiant temperature, can be subject to thermal effects due to overheating of some nearby components. A thermographic analysis was made to rule out this possibility. The paper shows how the pervasive technique of additive manufacturing can be combined with the more traditional thermographic techniques to redesign the case and to verify the accuracy of the optimized system in order to prevent instrumental systematic errors in terms of the difference between experimental and actual values of the above-mentioned environmental parameters. Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Electronic Conference on Sensors and Applications)

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15 pages, 12205 KiB

Open AccessArticle

Integrating Spherical Panoramas and Maps for Visualization of Cultural Heritage Objects Using Virtual Reality Technology

by Mila Koeva^1,*

, Mila Luleva² and Plamen Maldjanski³

¹ Faculty of Geo-information Science and Earth Observation, University of Twente, Hengelosestraat 99, 7514 AE Enschede, The Netherlands

² SoilCares Research BV, 6709 PA Wageningen, The Netherlands

³ University of Architecture Civil Engineering and Geodesy, Sofia 1164, Bulgaria

Sensors 2017, 17(4), 829; https://doi.org/10.3390/s17040829 - 11 Apr 2017

Cited by 76 | Viewed by 7856

Abstract

Development and virtual representation of 3D models of Cultural Heritage (CH) objects has triggered great interest over the past decade. The main reason for this is the rapid development in the fields of photogrammetry and remote sensing, laser scanning, and computer vision. The [...] Read more.

Development and virtual representation of 3D models of Cultural Heritage (CH) objects has triggered great interest over the past decade. The main reason for this is the rapid development in the fields of photogrammetry and remote sensing, laser scanning, and computer vision. The advantages of using 3D models for restoration, preservation, and documentation of valuable historical and architectural objects have been numerously demonstrated by scientists in the field. Moreover, 3D model visualization in virtual reality has been recognized as an efficient, fast, and easy way of representing a variety of objects worldwide for present-day users, who have stringent requirements and high expectations. However, the main focus of recent research is the visual, geometric, and textural characteristics of a single concrete object, while integration of large numbers of models with additional information—such as historical overview, detailed description, and location—are missing. Such integrated information can be beneficial, not only for tourism but also for accurate documentation. For that reason, we demonstrate in this paper an integration of high-resolution spherical panoramas, a variety of maps, GNSS, sound, video, and text information for representation of numerous cultural heritage objects. These are then displayed in a web-based portal with an intuitive interface. The users have the opportunity to choose freely from the provided information, and decide for themselves what is interesting to visit. Based on the created web application, we provide suggestions and guidelines for similar studies. We selected objects, which are located in Bulgaria—a country with thousands of years of history and cultural heritage dating back to ancient civilizations. The methods used in this research are applicable for any type of spherical or cylindrical images and can be easily followed and applied in various domains. After a visual and metric assessment of the panoramas and the evaluation of the web-portal, we conclude that this novel approach is a very effective, fast, informative, and accurate way to present, disseminate, and document cultural heritage objects. Full article

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14 pages, 4445 KiB

Open AccessArticle

Design and Implementation of an Intelligent Windowsill System Using Smart Handheld Device and Fuzzy Microcontroller

by Jing-Min Wang^*

, Ming-Ta Yang and Po-Lin Chen

Department of Electrical Engineering, St. John’s University, No. 499, Sec. 4, Tam King Rd., Tamsui Dist., New Taipei City 25135, Taiwan

Sensors 2017, 17(4), 830; https://doi.org/10.3390/s17040830 - 11 Apr 2017

Cited by 19 | Viewed by 8666

Abstract

With the advance of science and technology, people have a desire for convenient and comfortable living. Creating comfortable and healthy indoor environments is a major consideration for designing smart homes. As handheld devices become increasingly powerful and ubiquitous, this paper proposes an innovative [...] Read more.

With the advance of science and technology, people have a desire for convenient and comfortable living. Creating comfortable and healthy indoor environments is a major consideration for designing smart homes. As handheld devices become increasingly powerful and ubiquitous, this paper proposes an innovative use of smart handheld devices (SHD), using MIT App Inventor and fuzzy control, to perform the real-time monitoring and smart control of the designed intelligent windowsill system (IWS) in a smart home. A compact weather station that consists of environment sensors was constructed in the IWS for measuring of indoor illuminance, temperature-humidity, carbon dioxide (CO₂) concentration and outdoor rain and wind direction. According to the measured environment information, the proposed system can automatically send a command to a fuzzy microcontroller performed by Arduino UNO to fully or partly open the electric curtain and electric window for adapting to climate changes in the indoor and outdoor environment. Moreover, the IWS can automatically close windows for rain splashing on the window. The presented novel control method for the windowsill not only expands the SHD applications, but greatly enhances convenience to users. To validate the feasibility and effectiveness of the IWS, a laboratory prototype was built and confirmed experimentally. Full article

(This article belongs to the Special Issue Sensors for Home Automation and Security)

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9 pages, 2097 KiB

Open AccessArticle

Miniaturized Real-Time PCR on a Q3 System for Rapid KRAS Genotyping

by Maria Guarnaccia¹, Rosario Iemmolo¹

, Salvatore Petralia², Sabrina Conoci^2,*

and Sebastiano Cavallaro^1,*

¹ Institute of Neurological Sciences, Italian National Research Council, Via Paolo Gaifami, 18-95125 Catania, Italy

² STMicroelectronics, Stradale Primosole, 50-95121 Catania, Italy

Sensors 2017, 17(4), 831; https://doi.org/10.3390/s17040831 - 11 Apr 2017

Cited by 15 | Viewed by 4722

Abstract

Colorectal cancer (CRC) is an aggressive human malignancy with a complex genomic landscape harboring KRAS mutations. In 40%–60% of patients with CRC, constantly active KRAS proteins affect the prognosis, surgical strategy, and clinical benefit from therapy with anti-epidermal growth factor receptor (EGFR) agents. [...] Read more.

Colorectal cancer (CRC) is an aggressive human malignancy with a complex genomic landscape harboring KRAS mutations. In 40%–60% of patients with CRC, constantly active KRAS proteins affect the prognosis, surgical strategy, and clinical benefit from therapy with anti-epidermal growth factor receptor (EGFR) agents. For this reason, there is a greater demand for minimally-invasive diagnostic devices to characterize the genetic pattern and prevent the acquired mechanism to drug resistance. The rapid developments in cutting-edge diagnostic techniques are expected to play a growing role in medicine and represent an attractive promise to identify potential responders to personalized medicine. Here we propose a new method to simultaneously detect the main KRAS mutations on the portable real-time PCR Q3 platform. This platform is based on hybrid silicon-plastic technology implemented in a miniaturized chip able to achieve a sample-in answer-out rapid analysis, allowing a new approach to genetic counseling and testing. Full article

(This article belongs to the Section Biosensors)

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21 pages, 14272 KiB

Open AccessArticle

Use of the Magnetic Field for Improving Gyroscopes’ Biases Estimation

by Estefania Munoz Diaz^1,*, Fabian De Ponte Müller¹ and Juan Jesús García Domínguez²

¹ German Aerospace Center (DLR), Institute of Communications and Navigation, Oberpfaffenhofen, 82234 Wessling, Germany

² Electronic Department from the University of Alcalá, E.P.S. Campus Universitario, s/n, 28806 Alcalá de Henares, Spain

Sensors 2017, 17(4), 832; https://doi.org/10.3390/s17040832 - 11 Apr 2017

Cited by 7 | Viewed by 5278

Abstract

An accurate orientation is crucial to a satisfactory position in pedestrian navigation. The orientation estimation, however, is greatly affected by errors like the biases of gyroscopes. In order to minimize the error in the orientation, the biases of gyroscopes must be estimated and [...] Read more.

An accurate orientation is crucial to a satisfactory position in pedestrian navigation. The orientation estimation, however, is greatly affected by errors like the biases of gyroscopes. In order to minimize the error in the orientation, the biases of gyroscopes must be estimated and subtracted. In the state of the art it has been proposed, but not proved, that the estimation of the biases can be accomplished using magnetic field measurements. The objective of this work is to evaluate the effectiveness of using magnetic field measurements to estimate the biases of medium-cost micro-electromechanical sensors (MEMS) gyroscopes. We carry out the evaluation with experiments that cover both, quasi-error-free turn rate and magnetic measurements and medium-cost MEMS turn rate and magnetic measurements. The impact of different homogeneous magnetic field distributions and magnetically perturbed environments is analyzed. Additionally, the effect of the successful biases subtraction on the orientation and the estimated trajectory is detailed. Our results show that the use of magnetic field measurements is beneficial to the correct biases estimation. Further, we show that different magnetic field distributions affect differently the biases estimation process. Moreover, the biases are likewise correctly estimated under perturbed magnetic fields. However, for indoor and urban scenarios the biases estimation process is very slow. Full article

(This article belongs to the Special Issue Inertial Sensors and Systems 2016)

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18 pages, 7129 KiB

Open AccessArticle

Hand-Based Gesture Recognition for Vehicular Applications Using IR-UWB Radar

by Faheem Khan^†

, Seong Kyu Leem^†

and Sung Ho Cho^*

¹ Department of Electronics and Computer Engineering, Hanyang University, 222 Wangsimini-ro, Seongdong-gu, Seoul 133-791, Korea

^† Co-first authors, these authors contributed equally to this work.

Sensors 2017, 17(4), 833; https://doi.org/10.3390/s17040833 - 11 Apr 2017

Cited by 79 | Viewed by 13863

Abstract

Modern cars continue to offer more and more functionalities due to which they need a growing number of commands. As the driver tries to monitor the road and the graphic user interface simultaneously, his/her overall efficiency is reduced. In order to reduce the [...] Read more.

Modern cars continue to offer more and more functionalities due to which they need a growing number of commands. As the driver tries to monitor the road and the graphic user interface simultaneously, his/her overall efficiency is reduced. In order to reduce the visual attention necessary for monitoring, a gesture-based user interface is very important. In this paper, gesture recognition for a vehicle through impulse radio ultra-wideband (IR-UWB) radar is discussed. The gestures can be used to control different electronic devices inside a vehicle. The gestures are based on human hand and finger motion. We have implemented a real-time version using only one radar sensor. Studies on gesture recognition using IR-UWB radar have rarely been carried out, and some studies are merely simple methods using the magnitude of the reflected signal or those whose performance deteriorates largely due to changes in distance or direction. In this study, we propose a new hand-based gesture recognition algorithm that works robustly against changes in distance or direction while responding only to defined gestures by ignoring meaningless motions. We used three independent features, i.e., variance of the probability density function (pdf) of the magnitude histogram, time of arrival (TOA) variation and the frequency of the reflected signal, to classify the gestures. A data fitting method is included to differentiate between gesture signals and unintended hand or body motions. We have used the clustering technique for the classification of the gestures. Moreover, the distance information is used as an additional input parameter to the clustering algorithm, such that the recognition technique will not be vulnerable to distance change. The hand-based gesture recognition proposed in this paper would be a key technology of future automobile user interfaces. Full article

(This article belongs to the Special Issue Sensors and Sensing in Indoor Localization, Tracking, Navigation and Activity Monitoring)

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12 pages, 27362 KiB

Open AccessArticle

Modeling DGNSS Pseudo-Range Correction Messages by Utilizing Satellite Repeat Time

by Dong-Hyo Sohn^1,2, Kwan-Dong Park^1,*

and Hyunu Tae¹

¹ Department of Geoinformatic Engineering, Inha University, Incheon 22212, Korea

² Earthquake and Volcano Research Division, Earthquake and Volcano Center, Korea Meteorological Administration, Seoul 07062, Korea

Sensors 2017, 17(4), 834; https://doi.org/10.3390/s17040834 - 11 Apr 2017

Cited by 4 | Viewed by 4179

Abstract

We developed and validated a pseudo-range correction (PRC) modeling system that can prevent degradation of positioning accuracy even in situations where one cannot obtain PRC messages for Differential Global Navigation Satellite System (DGNSS). A PRC modeling scheme was devised based on the repeat [...] Read more.

We developed and validated a pseudo-range correction (PRC) modeling system that can prevent degradation of positioning accuracy even in situations where one cannot obtain PRC messages for Differential Global Navigation Satellite System (DGNSS). A PRC modeling scheme was devised based on the repeat time of GNSS satellites and previously-collected PRC data. The difference between the modeled and real PRC values observed at the reference station showed a bias error of about ±1.0 m and a root mean square error (RMSE) less than 1.5 m. When we applied the predicted PRC to Differential Global Positioning System (DGPS) and Differential BeiDou (DBDS) positioning, horizontal RMSE values were at a level of 1.0 m, while vertical RMSE was in the range of 1.8–3.0 m. We found that modelled PRCs can provide positioning results similar to those based on real PRCs and can provide significant improvement over standalone positioning without PRCs. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 2452 KiB

Open AccessArticle

Robust In-Flight Sensor Fault Diagnostics for Aircraft Engine Based on Sliding Mode Observers

by Xiaodong Chang

, Jinquan Huang^* and Feng Lu

Jiangsu Province Key Laboratory of Aerospace Power System, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

Sensors 2017, 17(4), 835; https://doi.org/10.3390/s17040835 - 11 Apr 2017

Cited by 24 | Viewed by 4460

Abstract

For a sensor fault diagnostic system of aircraft engines, the health performance degradation is an inevitable interference that cannot be neglected. To address this issue, this paper investigates an integrated on-line sensor fault diagnostic scheme for a commercial aircraft engine based on a [...] Read more.

For a sensor fault diagnostic system of aircraft engines, the health performance degradation is an inevitable interference that cannot be neglected. To address this issue, this paper investigates an integrated on-line sensor fault diagnostic scheme for a commercial aircraft engine based on a sliding mode observer (SMO). In this approach, one sliding mode observer is designed for engine health performance tracking, and another for sensor fault reconstruction. Both observers are employed in in-flight applications. The results of the former SMO are analyzed for post-flight updating the baseline model of the latter. This idea is practical and feasible since the updating process does not require the algorithm to be regulated or redesigned, so that ground-based intervention is avoided, and the update process is implemented in an economical and efficient way. With this setup, the robustness of the proposed scheme to the health degradation is much enhanced and the latter SMO is able to fulfill sensor fault reconstruction over the course of the engine life. The proposed sensor fault diagnostic system is applied to a nonlinear simulation of a commercial aircraft engine, and its effectiveness is evaluated in several fault scenarios. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 1937 KiB

Open AccessArticle

Direct Electrochemical Detection of Bisphenol A Using a Highly Conductive Graphite Nanoparticle Film Electrode

by Xinwei Dong¹, Xiaoli Qi¹, Na Liu¹, Yuesuo Yang^1,2

and Yunxian Piao^1,*

¹ Key Laboratory of Ground Water Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, 2519 Jiefang Road, Changchun 130021, China

² Key Laboratory of Eco-restoration of Regional Contaminated Environment, Shenyang University, Shenyang 110044, China

Sensors 2017, 17(4), 836; https://doi.org/10.3390/s17040836 - 11 Apr 2017

Cited by 40 | Viewed by 5610

Abstract

We developed an accurate and sensitive sensor for electrochemical detection of bisphenol A (BPA) with a high-conductivity graphite nanoparticle (GN) film electrode. The GNs consisted of several stacked graphene sheets and showed a homogenous spherical shape, high conductivity, large surface area and good [...] Read more.

We developed an accurate and sensitive sensor for electrochemical detection of bisphenol A (BPA) with a high-conductivity graphite nanoparticle (GN) film electrode. The GNs consisted of several stacked graphene sheets and showed a homogenous spherical shape, high conductivity, large surface area and good adsorption properties to BPA. The constructed GN film electrode exhibited improved amperometric current responses such as decreased impedance and lowered BPA oxidation potential compared with those of a pristine electrode, and also possessed a large surface area to allow fast electron transfer and BPA accumulation. A pre-accumulation process with BPA adsorption resulted in considerable current signal enhancement during BPA detection. The loading amount of GNs on the film electrode and the time for target BPA enrichment were optimized. The GN film electrode-based sensor showed high reproducibility and high selectivity for BPA over other reagents. Differential pulse voltammetry experiments revealed that the concentrations of BPA were linearly correlated with the current changes, and the lowest limit of detection of the sensor was 35 nM. Furthermore, the sensor showed great accuracy and reliability, as confirmed by high-performance liquid chromatography measurements. The sensor was also successfully used for BPA determination in groundwater samples, demonstrating its potential for real environmental analysis. Full article

(This article belongs to the Special Issue Sensors for Biomedical, Environmental and Food Monitoring Applications)

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20 pages, 4520 KiB

Open AccessArticle

Registration of Vehicle-Borne Point Clouds and Panoramic Images Based on Sensor Constellations

by Lianbi Yao¹, Hangbin Wu^1,*, Yayun Li¹, Bin Meng¹, Jinfei Qian¹, Chun Liu¹

and Hongchao Fan²

¹ College of Surveying and Geoinformatics, Tongji University, Shanghai 200092, China

² Institute of Geography, Heidelberg University, Heidelberg D-69120, Germany

Sensors 2017, 17(4), 837; https://doi.org/10.3390/s17040837 - 11 Apr 2017

Cited by 12 | Viewed by 4231

Abstract

A mobile mapping system (MMS) is usually utilized to collect environmental data on and around urban roads. Laser scanners and panoramic cameras are the main sensors of an MMS. This paper presents a new method for the registration of the point clouds and [...] Read more.

A mobile mapping system (MMS) is usually utilized to collect environmental data on and around urban roads. Laser scanners and panoramic cameras are the main sensors of an MMS. This paper presents a new method for the registration of the point clouds and panoramic images based on sensor constellation. After the sensor constellation was analyzed, a feature point, the intersection of the connecting line between the global positioning system (GPS) antenna and the panoramic camera with a horizontal plane, was utilized to separate the point clouds into blocks. The blocks for the central and sideward laser scanners were extracted with the segmentation feature points. Then, the point clouds located in the blocks were separated from the original point clouds. Each point in the blocks was used to find the accurate corresponding pixel in the relative panoramic images via a collinear function, and the position and orientation relationship amongst different sensors. A search strategy is proposed for the correspondence of laser scanners and lenses of panoramic cameras to reduce calculation complexity and improve efficiency. Four cases of different urban road types were selected to verify the efficiency and accuracy of the proposed method. Results indicate that most of the point clouds (with an average of 99.7%) were successfully registered with the panoramic images with great efficiency. Geometric evaluation results indicate that horizontal accuracy was approximately 0.10–0.20 m, and vertical accuracy was approximately 0.01–0.02 m for all cases. Finally, the main factors that affect registration accuracy, including time synchronization amongst different sensors, system positioning and vehicle speed, are discussed. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 4268 KiB

Open AccessArticle

Piezoelectric Actuated Phase Shifter Based on External Laser Interferometer: Design, Control and Experimental Validation

by Peng-Zhi Li^1,2,*, Xiao-Dong Wang^1,*, Yong-Xin Sui¹, De-Fu Zhang¹, Dong-Fang Wang^1,2, Li-Jian Dong¹ and Ming-Yang Ni¹

¹ Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China

² University of Chinese Academy of Sciences, Beijing 100049, China

Sensors 2017, 17(4), 838; https://doi.org/10.3390/s17040838 - 11 Apr 2017

Cited by 14 | Viewed by 5791

Abstract

To improve the phase-shifting accuracy, this paper presents a novel integrated framework for design, control and experimental validation of the piezoelectric actuated phase shifter with a trade-off between accuracy and cost. The piezoelectric actuators with built-in sensors are adopted to drive the double [...] Read more.

To improve the phase-shifting accuracy, this paper presents a novel integrated framework for design, control and experimental validation of the piezoelectric actuated phase shifter with a trade-off between accuracy and cost. The piezoelectric actuators with built-in sensors are adopted to drive the double parallel four-bar linkage flexure hinge-based mechanisms. Three mechanisms form the tripod structure of the assembled phase shifter. Then, a semi-closed loop controller with inner feedback and outer feedforward loops via the external laser interferometer is developed for accurate positioning of the phase shifter. Finally, experiments related with travel range, step response, linearity and repeatability are carried out. The linearity error is 0.21% and the repeatability error of 10

μ

m displacement is 3 nm. The results clearly demonstrate the good performance of the developed phase shifter and the feasibility of the proposed integrated framework. Full article

(This article belongs to the Special Issue Piezoelectric Micro- and Nano-Devices)

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12 pages, 3124 KiB

Open AccessArticle

Fructose and Pectin Detection in Fruit-Based Food Products by Surface-Enhanced Raman Spectroscopy

by Carlo Camerlingo¹, Marianna Portaccio²

, Rosarita Tatè³, Maria Lepore^2,*

and Ines Delfino^4,*

¹ CNR-SPIN, Istituto Superconduttori, Materiali Innovativi e Dispositivi, 80078 Pozzuoli (Na), Italy

² Dipartimento di Medicina Sperimentale, Università della Campania “Luigi Vanvitelli”, 80138 Naples, Italy

³ Institute of Genetics and Biophysics—ABT, CNR, 80131 Naples, Italy

⁴ Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia, 01100 Viterbo, Italy

Sensors 2017, 17(4), 839; https://doi.org/10.3390/s17040839 - 11 Apr 2017

Cited by 27 | Viewed by 7701

Abstract

Surface-Enhanced Raman Spectroscopy (SERS) enables the investigation of samples with weak specific Raman signals, such as opaque samples, including fruit juices and pulp. In this paper, biological apple juices and apple/pear pulp have been studied in order to evidence the presence of fructose [...] Read more.

Surface-Enhanced Raman Spectroscopy (SERS) enables the investigation of samples with weak specific Raman signals, such as opaque samples, including fruit juices and pulp. In this paper, biological apple juices and apple/pear pulp have been studied in order to evidence the presence of fructose and pectin, which are components of great relevance for quality assessment of these kinds of products. In order to perform SERS measurements a low-cost home-made substrate consisting of a glass slide decorated with 30-nm-sized gold nanoparticles has been designed and used. By employing a conventional micro-Raman spectroscopy set-up and a suitable data treatment based on “wavelet” denoising algorithms and background subtraction, spectra of pectin and fructose with clear Raman features have been obtained. The results have confirmed the potential of SERS in the food industry for product characterization, also considering the low-cost and the relative ease of the fabrication process of the employed SERS substrate. Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Electronic Conference on Sensors and Applications)

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15 pages, 2343 KiB

Open AccessCommunication

Fast Noncircular 2D-DOA Estimation for Rectangular Planar Array

by Lingyun Xu^1,2,* and Fangqing Wen³

¹ College of Science, Nanjing University of Aeronautics & Astronautics, Nanjing 210016, China

² Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, USA

³ Electronic and Information School of Yangtze University, Jingzhou 434023, China

Sensors 2017, 17(4), 840; https://doi.org/10.3390/s17040840 - 12 Apr 2017

Cited by 5 | Viewed by 5504

Abstract

A novel scheme is proposed for direction finding with uniform rectangular planar array. First, the characteristics of noncircular signals and Euler’s formula are exploited to construct a new real-valued rectangular array data. Then, the rotational invariance relations for real-valued signal space are depicted [...] Read more.

A novel scheme is proposed for direction finding with uniform rectangular planar array. First, the characteristics of noncircular signals and Euler’s formula are exploited to construct a new real-valued rectangular array data. Then, the rotational invariance relations for real-valued signal space are depicted in a new way. Finally the real-valued propagator method is utilized to estimate the pairing two-dimensional direction of arrival (2D-DOA). The proposed algorithm provides better angle estimation performance and can discern more sources than the 2D propagator method. At the same time, it has very close angle estimation performance to the noncircular propagator method (NC-PM) with reduced computational complexity. Full article

(This article belongs to the Special Issue Recent Advances in Array Signal Processing and Its Applications in IoT Security)

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7 pages, 873 KiB

Open AccessFeature PaperArticle

Wireless Fractal Ultra-Dense Cellular Networks

by Yixue Hao¹, Min Chen^1,*, Long Hu¹, Jeungeun Song¹, Mojca Volk² and Iztok Humar²

¹ School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China

² Laboratory for Telecommunications, Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, SI-1000 Ljubljan, Slovenia

Sensors 2017, 17(4), 841; https://doi.org/10.3390/s17040841 - 12 Apr 2017

Cited by 27 | Viewed by 7747

Abstract

With the ever-growing number of mobile devices, there is an explosive expansion in mobile data services. This represents a challenge for the traditional cellular network architecture to cope with the massive wireless traffic generated by mobile media applications. To meet this challenge, research [...] Read more.

With the ever-growing number of mobile devices, there is an explosive expansion in mobile data services. This represents a challenge for the traditional cellular network architecture to cope with the massive wireless traffic generated by mobile media applications. To meet this challenge, research is currently focused on the introduction of a small cell base station (BS) due to its low transmit power consumption and flexibility of deployment. However, due to a complex deployment environment and low transmit power of small cell BSs, the coverage boundary of small cell BSs will not have a traditional regular shape. Therefore, in this paper, we discuss the coverage boundary of an ultra-dense small cell network and give its main features: aeolotropy of path loss fading and fractal coverage boundary. Simple performance analysis is given, including coverage probability and transmission rate, etc., based on stochastic geometry theory and fractal theory. Finally, we present an application scene and discuss challenges in the ultra-dense small cell network. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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11 pages, 3893 KiB

Open AccessArticle

A Cost-Effective Geodetic Strainmeter Based on Dual Coaxial Cable Bragg Gratings

by Jihua Fu^1,*, Xu Wang¹, Tao Wei², Meng Wei³ and Yang Shen³

¹ Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration; Beijing 100085, China

² Engineering Department, University of Rhode Island, Kingston, RI 02881, USA

³ Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA

Sensors 2017, 17(4), 842; https://doi.org/10.3390/s17040842 - 12 Apr 2017

Cited by 13 | Viewed by 5187

Abstract

Observations of surface deformation are essential for understanding a wide range of geophysical problems, including earthquakes, volcanoes, landslides, and glaciers. Current geodetic technologies, such as global positioning system (GPS), interferometric synthetic aperture radar (InSAR), borehole and laser strainmeters, are costly and limited in [...] Read more.

Observations of surface deformation are essential for understanding a wide range of geophysical problems, including earthquakes, volcanoes, landslides, and glaciers. Current geodetic technologies, such as global positioning system (GPS), interferometric synthetic aperture radar (InSAR), borehole and laser strainmeters, are costly and limited in their temporal or spatial resolutions. Here we present a new type of strainmeters based on the coaxial cable Bragg grating (CCBG) sensing technology that provides cost-effective strain measurements. Two CCBGs are introduced into the geodetic strainmeter: one serves as a sensor to measure the strain applied on it, and the other acts as a reference to detect environmental noises. By integrating the sensor and reference signals in a mixer, the environmental noises are minimized and a lower mixed frequency is obtained. The lower mixed frequency allows for measurements to be taken with a portable spectrum analyzer, rather than an expensive spectrum analyzer or a vector network analyzer (VNA). Analysis of laboratory experiments shows that the strain can be measured by the CCBG sensor, and the portable spectrum analyzer can make measurements with the accuracy similar to the expensive spectrum analyzer, whose relative error to the spectrum analyzer R3272 is less than ±0.4%. The outputs of the geodetic strainmeter show a linear relationship with the strains that the CCBG sensor experienced. The measured sensitivity of the geodetic strainmeter is about −0.082 kHz/με; it can cover a large dynamic measuring range up to 2%, and its nonlinear errors can be less than 5.3%. Full article

(This article belongs to the Special Issue Recent Advances in Fiber Bragg Grating Sensing)

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19 pages, 402 KiB

Open AccessArticle

Random Finite Set Based Bayesian Filtering with OpenCL in a Heterogeneous Platform

by Biao Hu^1,†, Uzair Sharif^1,†, Rajat Koner¹, Guang Chen¹, Kai Huang^2,*, Feihu Zhang³

, Walter Stechele⁴ and Alois Knoll¹

¹ Robotics and Embedded Systems, Technische Universität München, 80333 München, Germany

² School of Data and Computer Science, Sun Yat-sen University, Xiaoguwei Island, Panyu District, Guangzhou 510006, China

³ School of Marine Science and Technology, Northwestern Polytechnical University, 127, Youyi West Road, Xi’an 710072, China

⁴ Integrated Systems, Technische Universität München, 80333 München, Germany

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 843; https://doi.org/10.3390/s17040843 - 12 Apr 2017

Cited by 1 | Viewed by 4970

Abstract

While most filtering approaches based on random finite sets have focused on improving performance, in this paper, we argue that computation times are very important in order to enable real-time applications such as pedestrian detection. Towards this goal, this paper investigates the use [...] Read more.

While most filtering approaches based on random finite sets have focused on improving performance, in this paper, we argue that computation times are very important in order to enable real-time applications such as pedestrian detection. Towards this goal, this paper investigates the use of OpenCL to accelerate the computation of random finite set-based Bayesian filtering in a heterogeneous system. In detail, we developed an efficient and fully-functional pedestrian-tracking system implementation, which can run under real-time constraints, meanwhile offering decent tracking accuracy. An extensive evaluation analysis was carried out to ensure the fulfillment of sufficient accuracy requirements. This was followed by extensive profiling analysis to spot the potential bottlenecks in terms of execution performance, which were then targeted to come up with an OpenCL accelerated application. Video-throughput improvements from roughly 15 fps to 100 fps (6×) were observed on average while processing typical MOT benchmark videos. Moreover, the worst-case frame processing yielded an 18× advantage from nearly 2 fps to 36 fps, thereby comfortably meeting the real-time constraints. Our implementation is released as open-source code. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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15 pages, 3432 KiB

Open AccessArticle

Variable Admittance Control Based on Fuzzy Reinforcement Learning for Minimally Invasive Surgery Manipulator

by Zhijiang Du, Wei Wang, Zhiyuan Yan, Wei Dong and Weidong Wang^*

State Key Laboratory of Robotics and System, Harbin Institute of Technology, 2 Yikuang Street, Harbin 150080, China

Sensors 2017, 17(4), 844; https://doi.org/10.3390/s17040844 - 12 Apr 2017

Cited by 52 | Viewed by 6308

Abstract

In order to get natural and intuitive physical interaction in the pose adjustment of the minimally invasive surgery manipulator, a hybrid variable admittance model based on Fuzzy Sarsa(λ)-learning is proposed in this paper. The proposed model provides continuous variable virtual damping to the [...] Read more.

In order to get natural and intuitive physical interaction in the pose adjustment of the minimally invasive surgery manipulator, a hybrid variable admittance model based on Fuzzy Sarsa(λ)-learning is proposed in this paper. The proposed model provides continuous variable virtual damping to the admittance controller to respond to human intentions, and it effectively enhances the comfort level during the task execution by modifying the generated virtual damping dynamically. A fuzzy partition defined over the state space is used to capture the characteristics of the operator in physical human-robot interaction. For the purpose of maximizing the performance index in the long run, according to the identification of the current state input, the virtual damping compensations are determined by a trained strategy which can be learned through the experience generated from interaction with humans, and the influence caused by humans and the changing dynamics in the robot are also considered in the learning process. To evaluate the performance of the proposed model, some comparative experiments in joint space are conducted on our experimental minimally invasive surgical manipulator. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 2423 KiB

Open AccessArticle

A Classification Method for Seed Viability Assessment with Infrared Thermography

by Sen Men, Lei Yan^*, Jiaxin Liu, Hua Qian and Qinjuan Luo

School of Technology, Beijing Forestry University, Beijing 100083, China

Sensors 2017, 17(4), 845; https://doi.org/10.3390/s17040845 - 12 Apr 2017

Cited by 34 | Viewed by 5694

Abstract

This paper presents a viability assessment method for Pisum sativum L. seeds based on the infrared thermography technique. In this work, different artificial treatments were conducted to prepare seeds samples with different viability. Thermal images and visible images were recorded every five minutes [...] Read more.

This paper presents a viability assessment method for Pisum sativum L. seeds based on the infrared thermography technique. In this work, different artificial treatments were conducted to prepare seeds samples with different viability. Thermal images and visible images were recorded every five minutes during the standard five day germination test. After the test, the root length of each sample was measured, which can be used as the viability index of that seed. Each individual seed area in the visible images was segmented with an edge detection method, and the average temperature of the corresponding area in the infrared images was calculated as the representative temperature for this seed at that time. The temperature curve of each seed during germination was plotted. Thirteen characteristic parameters extracted from the temperature curve were analyzed to show the difference of the temperature fluctuations between the seeds samples with different viability. With above parameters, support vector machine (SVM) was used to classify the seed samples into three categories: viable, aged and dead according to the root length, the classification accuracy rate was 95%. On this basis, with the temperature data of only the first three hours during the germination, another SVM model was proposed to classify the seed samples, and the accuracy rate was about 91.67%. From these experimental results, it can be seen that infrared thermography can be applied for the prediction of seed viability, based on the SVM algorithm. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 1194 KiB

Open AccessArticle

Implementation and Analysis of Real-Time Streaming Protocols

by Iván Santos-González^*, Alexandra Rivero-García^*

, Jezabel Molina-Gil^* and Pino Caballero-Gil^*

Department of Computer Engineering and Systems, University of La Laguna, 38206 Tenerife, Spain

Sensors 2017, 17(4), 846; https://doi.org/10.3390/s17040846 - 12 Apr 2017

Cited by 32 | Viewed by 10266

Abstract

Communication media have become the primary way of interaction thanks to the discovery and innovation of many new technologies. One of the most widely used communication systems today is video streaming, which is constantly evolving. Such communications are a good alternative to face-to-face [...] Read more.

Communication media have become the primary way of interaction thanks to the discovery and innovation of many new technologies. One of the most widely used communication systems today is video streaming, which is constantly evolving. Such communications are a good alternative to face-to-face meetings, and are therefore very useful for coping with many problems caused by distance. However, they suffer from different issues such as bandwidth limitation, network congestion, energy efficiency, cost, reliability and connectivity. Hence, the quality of service and the quality of experience are considered the two most important issues for this type of communication. This work presents a complete comparative study of two of the most used protocols of video streaming, Real Time Streaming Protocol (RTSP) and the Web Real-Time Communication (WebRTC). In addition, this paper proposes two new mobile applications that implement those protocols in Android whose objective is to know how they are influenced by the aspects that most affect the streaming quality of service, which are the connection establishment time and the stream reception time. The new video streaming applications are also compared with the most popular video streaming applications for Android, and the experimental results of the analysis show that the developed WebRTC implementation improves the performance of the most popular video streaming applications with respect to the stream packet delay. Full article

(This article belongs to the Special Issue Selected Papers from UCAmI 2016)

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24 pages, 4456 KiB

Open AccessArticle

Modeling Infrared Signal Reflections to Characterize Indoor Multipath Propagation

by Álvaro De-La-Llana-Calvo¹, José Luis Lázaro-Galilea^1,*

, Alfredo Gardel-Vicente¹

, David Rodríguez-Navarro¹, Ignacio Bravo-Muñoz¹

, Georgios Tsirigotis² and Juan Iglesias-Miguel¹

¹ Department of electronics, University of Alcalá, Alcalá de Henares, 28801 Madrid, Spain

² Informatics Engineering Department, Eastern Macedonia and Thrace Institute of Technology, 65404 Kavala, Greece

Sensors 2017, 17(4), 847; https://doi.org/10.3390/s17040847 - 13 Apr 2017

Cited by 16 | Viewed by 5576

Abstract

In this paper, we propose a model to characterize Infrared (IR) signal reflections on any kind of surface material, together with a simplified procedure to compute the model parameters. The model works within the framework of Local Positioning Systems (LPS) based on IR [...] Read more.

In this paper, we propose a model to characterize Infrared (IR) signal reflections on any kind of surface material, together with a simplified procedure to compute the model parameters. The model works within the framework of Local Positioning Systems (LPS) based on IR signals (IR-LPS) to evaluate the behavior of transmitted signal Multipaths (MP), which are the main cause of error in IR-LPS, and makes several contributions to mitigation methods. Current methods are based on physics, optics, geometry and empirical methods, but these do not meet our requirements because of the need to apply several different restrictions and employ complex tools. We propose a simplified model based on only two reflection components, together with a method for determining the model parameters based on 12 empirical measurements that are easily performed in the real environment where the IR-LPS is being applied. Our experimental results show that the model provides a comprehensive solution to the real behavior of IR MP, yielding small errors when comparing real and modeled data (the mean error ranges from 1% to 4% depending on the environment surface materials). Other state-of-the-art methods yielded mean errors ranging from 15% to 40% in test measurements. Full article

(This article belongs to the Special Issue Sensors and Sensing in Indoor Localization, Tracking, Navigation and Activity Monitoring)

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18 pages, 726 KiB

Open AccessArticle

Autonomous Car Parking System through a Cooperative Vehicular Positioning Network

by Alejandro Correa^*

, Guillem Boquet, Antoni Morell

and Jose Lopez Vicario

Telecommunications and Systems Engineering Department, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain

Sensors 2017, 17(4), 848; https://doi.org/10.3390/s17040848 - 13 Apr 2017

Cited by 22 | Viewed by 7422

Abstract

The increasing development of the automotive industry towards a fully autonomous car has motivated the design of new value-added services in Vehicular Sensor Networks (VSNs). Within the context of VSNs, the autonomous car, with an increasing number of on-board sensors, is a mobile [...] Read more.

The increasing development of the automotive industry towards a fully autonomous car has motivated the design of new value-added services in Vehicular Sensor Networks (VSNs). Within the context of VSNs, the autonomous car, with an increasing number of on-board sensors, is a mobile node that exchanges sensed and state information within the VSN. Among all the value added services for VSNs, the design of new intelligent parking management architectures where the autonomous car will coexist with traditional cars is mandatory in order to profit from all the opportunities associated with the increasing intelligence of the new generation of cars. In this work, we design a new smart parking system on top of a VSN that takes into account the heterogeneity of cars and provides guidance to the best parking place for the autonomous car based on a collaborative approach that searches for the common good of all of them measured by the accessibility rate, which is the ratio of the free parking places accessible for an autonomous car. Then, we simulate a real parking lot and the results show that the performance of our system is close to the optimum considering different communication ranges and penetration rates for the autonomous car. Full article

(This article belongs to the Section State-of-the-Art Sensors Technologies)

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9 pages, 2248 KiB

Open AccessCommunication

A New Strategy for Silver Deposition on Au Nanoparticles with the Use of Peroxidase-Mimicking DNAzyme Monitored via a Localized Surface Plasmon Resonance Technique

by Joanna Kosman^1,*,†, Jacqueline Jatschka^2,†, Andrea Csaki², Wolfgang Fritzsche², Bernard Juskowiak¹

and Ondrej Stranik²

¹ Laboratory of Bioanalytical Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznan, Poland

² Department of Nano Biophotonics, Leibniz Institute of Photonic Technology (IPHT), 07745 Jena, Germany

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 849; https://doi.org/10.3390/s17040849 - 13 Apr 2017

Cited by 5 | Viewed by 4387

Abstract

Peroxidase-mimicking DNAzyme was applied as a catalyst of silver deposition on gold nanoparticles. This DNAzyme is formed when hemin binds to the G-quadruplex-forming DNA sequence. Such a system is able to catalyze a redox reaction with a one- or two-electron transfer. The process [...] Read more.

Peroxidase-mimicking DNAzyme was applied as a catalyst of silver deposition on gold nanoparticles. This DNAzyme is formed when hemin binds to the G-quadruplex-forming DNA sequence. Such a system is able to catalyze a redox reaction with a one- or two-electron transfer. The process of silver deposition was monitored via a localized surface plasmon resonance technique (LSPR), which allows one to record scattering spectrum of a single nanoparticle. Our study showed that DNAzyme is able to catalyze silver deposition. The AFM experiments proved that DNAzyme induced the deposition of silver shells of approximately 20 nm thickness on Au nanoparticles (AuNPs). Such an effect is not observed when hemin is absent in the system. However, we noticed non-specific binding of hemin to the capture oligonucleotides on a gold NP probe that also induced some silver deposition, even though the capture probe was unable to form G-quadruplex. Analysis of SEM images indicated that the surface morphology of the silver layer deposited by DNAzyme is different from that obtained for hemin alone. The proposed strategy of silver layer synthesis on gold nanoparticles catalyzed by DNAzyme is an innovative approach and can be applied in bioanalysis (LSPR, electrochemistry) as well as in material sciences. Full article

(This article belongs to the Section State-of-the-Art Sensors Technologies)

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13 pages, 2608 KiB

Open AccessArticle

PVDF Sensor Stimulated by Infrared Radiation for Temperature Monitoring in Microfluidic Devices

by Salvatore A. Pullano^1,2,*, Ifana Mahbub²

, Syed K. Islam² and Antonino S. Fiorillo¹

¹ Department of Health Sciences, University Magna Græcia of Catanzaro, Viale Europa, 88100 Catanzaro, Italy

² Department of Electrical Engineering and Computer Science, University of Tennessee, 1520 Middle Drive, Knoxville, TN 37996, USA

Sensors 2017, 17(4), 850; https://doi.org/10.3390/s17040850 - 13 Apr 2017

Cited by 33 | Viewed by 8946

Abstract

This paper presents a ferroelectric polymer-based temperature sensor designed for microfluidic devices. The integration of the sensor into a system-on-a-chip platform facilitates quick monitoring of localized temperature of a biological fluid, avoiding errors in the evaluation of thermal evolution of the fluid during [...] Read more.

This paper presents a ferroelectric polymer-based temperature sensor designed for microfluidic devices. The integration of the sensor into a system-on-a-chip platform facilitates quick monitoring of localized temperature of a biological fluid, avoiding errors in the evaluation of thermal evolution of the fluid during analysis. The contact temperature sensor is fabricated by combining a thin pyroelectric film together with an infrared source, which stimulates the active element located on the top of the microfluidic channel. An experimental setup was assembled to validate the analytical model and to characterize the response rate of the device. The evaluation procedure and the operating range of the temperature also make this device suitable for applications where the localized temperature monitoring of biological samples is necessary. Additionally, ease of integration with standard microfluidic devices makes the proposed sensor an attractive option for in situ analysis of biological fluids. Full article

(This article belongs to the Special Issue Piezoelectric Micro- and Nano-Devices)

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28 pages, 10692 KiB

Open AccessArticle

Improved Object Detection Using a Robotic Sensing Antenna with Vibration Damping Control

by Vicente Feliu-Batlle^1,*, Daniel Feliu-Talegon² and Claudia Fernanda Castillo-Berrio³

¹ Escuela Técnica Superior de Ingenieros Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain

² Instituto de Investigaciones Energéticas y Aplicaciones Industriales (INEI), Campus Universitario de Ciudad Real, 13071 Ciudad Real, Spain

³ Engineering and Architecture Faculty, Mechatronic Engineering, Istanbul Gelisim University, Cihangir mah. Sehit Jandarma Komando Er Hakan Oner Sk. No. 1 Avcilar, 34351 Istanbul, Turkey

Sensors 2017, 17(4), 852; https://doi.org/10.3390/s17040852 - 13 Apr 2017

Cited by 19 | Viewed by 5558

Abstract

Some insects or mammals use antennae or whiskers to detect by the sense of touch obstacles or recognize objects in environments in which other senses like vision cannot work. Artificial flexible antennae can be used in robotics to mimic this sense of touch [...] Read more.

Some insects or mammals use antennae or whiskers to detect by the sense of touch obstacles or recognize objects in environments in which other senses like vision cannot work. Artificial flexible antennae can be used in robotics to mimic this sense of touch in these recognition tasks. We have designed and built a two-degree of freedom (2DOF) flexible antenna sensor device to perform robot navigation tasks. This device is composed of a flexible beam, two servomotors that drive the beam and a load cell sensor that detects the contact of the beam with an object. It is found that the efficiency of such a device strongly depends on the speed and accuracy achieved by the antenna positioning system. These issues are severely impaired by the vibrations that appear in the antenna during its movement. However, these antennae are usually moved without taking care of these undesired vibrations. This article proposes a new closed-loop control schema that cancels vibrations and improves the free movements of the antenna. Moreover, algorithms to estimate the 3D beam position and the instant and point of contact with an object are proposed. Experiments are reported that illustrate the efficiency of these proposed algorithms and the improvements achieved in object detection tasks using a control system that cancels beam vibrations. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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32 pages, 27589 KiB

Open AccessArticle

Real-Time (Vision-Based) Road Sign Recognition Using an Artificial Neural Network

by Kh Tohidul Islam

and Ram Gopal Raj^*

Department of Artificial Intelligence, Faculty of Computer Science & Information Technology, University of Malaya, Kuala Lumpur 50603, Malaysia

Sensors 2017, 17(4), 853; https://doi.org/10.3390/s17040853 - 13 Apr 2017

Cited by 56 | Viewed by 22849

Abstract

Road sign recognition is a driver support function that can be used to notify and warn the driver by showing the restrictions that may be effective on the current stretch of road. Examples for such regulations are ‘traffic light ahead’ or ‘pedestrian crossing’ [...] Read more.

Road sign recognition is a driver support function that can be used to notify and warn the driver by showing the restrictions that may be effective on the current stretch of road. Examples for such regulations are ‘traffic light ahead’ or ‘pedestrian crossing’ indications. The present investigation targets the recognition of Malaysian road and traffic signs in real-time. Real-time video is taken by a digital camera from a moving vehicle and real world road signs are then extracted using vision-only information. The system is based on two stages, one performs the detection and another one is for recognition. In the first stage, a hybrid color segmentation algorithm has been developed and tested. In the second stage, an introduced robust custom feature extraction method is used for the first time in a road sign recognition approach. Finally, a multilayer artificial neural network (ANN) has been created to recognize and interpret various road signs. It is robust because it has been tested on both standard and non-standard road signs with significant recognition accuracy. This proposed system achieved an average of 99.90% accuracy with 99.90% of sensitivity, 99.90% of specificity, 99.90% of f-measure, and 0.001 of false positive rate (FPR) with 0.3 s computational time. This low FPR can increase the system stability and dependability in real-time applications. Full article

(This article belongs to the Special Issue Sensors for Transportation)

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22 pages, 5086 KiB

Open AccessArticle

homeSound: Real-Time Audio Event Detection Based on High Performance Computing for Behaviour and Surveillance Remote Monitoring

by Rosa Ma Alsina-Pagès^1,*

, Joan Navarro²

, Francesc Alías¹

and Marcos Hervás¹

¹ GTM—Grup de recerca en Tecnologies Mèdia, La Salle—Universitat Ramon Llull, C/Quatre Camins, 30, 08022 Barcelona, Catalonia, Spain

² GRITS—Grup de Recerca en Internet Technologies & Storage, La Salle—Universitat Ramon Llull, C/Quatre Camins, 30, 08022 Barcelona, Catalonia, Spain

Sensors 2017, 17(4), 854; https://doi.org/10.3390/s17040854 - 13 Apr 2017

Cited by 72 | Viewed by 10929

Abstract

The consistent growth in human life expectancy during the recent years has driven governments and private organizations to increase the efforts in caring for the eldest segment of the population. These institutions have built hospitals and retirement homes that have been rapidly overfilled, [...] Read more.

The consistent growth in human life expectancy during the recent years has driven governments and private organizations to increase the efforts in caring for the eldest segment of the population. These institutions have built hospitals and retirement homes that have been rapidly overfilled, making their associated maintenance and operating costs prohibitive. The latest advances in technology and communications envisage new ways to monitor those people with special needs at their own home, increasing their quality of life in a cost-affordable way. The purpose of this paper is to present an Ambient Assisted Living (AAL) platform able to analyze, identify, and detect specific acoustic events happening in daily life environments, which enables the medic staff to remotely track the status of every patient in real-time. Additionally, this tele-care proposal is validated through a proof-of-concept experiment that takes benefit of the capabilities of the NVIDIA Graphical Processing Unit running on a Jetson TK1 board to locally detect acoustic events. Conducted experiments demonstrate the feasibility of this approach by reaching an overall accuracy of 82% when identifying a set of 14 indoor environment events related to the domestic surveillance and patients’ behaviour monitoring field. Obtained results encourage practitioners to keep working in this direction, and enable health care providers to remotely track the status of their patients in real-time with non-invasive methods. Full article

(This article belongs to the Special Issue Sensors for Ambient Assisted Living, Ubiquitous and Mobile Health)

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11 pages, 2870 KiB

Open AccessArticle

The Use of a Pressure-Indicating Film to Determine the Effect of Liner Type on the Measured Teat Load Caused by a Collapsing Liner

by Susanne Demba^1,*, Viktoria Paul¹, Christian Ammon¹

and Sandra Rose-Meierhöfer²

¹ Leibniz-Institute for Agricultural Engineering and Bioeconomy e.V. (ATB), Department of Engineering for Livestock Management, Max-Eyth-Allee 100, Potsdam 14469, Germany

² Hochschule Neubrandenburg, University of Applied Sciences, Department of Agricultural Machinery, Brodaer Straße 2, Neubrandenburg 17033, Germany

Sensors 2017, 17(4), 855; https://doi.org/10.3390/s17040855 - 13 Apr 2017

Viewed by 4556

Abstract

During milking the teat cup liner is the interface between the teat of a dairy cow and the milking system, so it should be very well adapted to the teat. Therefore, the aim of the present study was to determine the effect of [...] Read more.

During milking the teat cup liner is the interface between the teat of a dairy cow and the milking system, so it should be very well adapted to the teat. Therefore, the aim of the present study was to determine the effect of liner type on the directly measuring teat load caused by a collapsing liner with a pressure-indicating film. The Extreme Low pressure-indicating film was used to detect the effect of six different liners on teat load. For each liner, six positions in the teat cup were specified, and six repetitions were performed for each position with a new piece of film each time. Analysis of variance was performed to detect differences between the six liners, the positions within a liner, and the measuring areas. The pressure applied to the teat by a liner depends on the technical characteristics of the liner, especially the shape of the barrel, and for all tested liners, a higher teat load was found at the teat end. In conclusion, with the help of pressure-indicating film, it is possible to determine the different effects of liner type by directly measuring teat load due to liner collapse. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 2615 KiB

Open AccessArticle

Easy-to-Fabricate and High-Sensitivity LSPR Type Specific Protein Detection Sensor Using AAO Nano-Pore Size Control

by Sae-Wan Kim¹, Jae-Sung Lee¹, Sang-Won Lee¹, Byoung-Ho Kang², Jin-Beom Kwon¹, Ok-Sik Kim¹, Ju-Seong Kim¹, Eung-Soo Kim³, Dae-Hyuk Kwon⁴ and Shin-Won Kang^1,*

¹ School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 1370 Sankyuk-dong, Bukgu, 702-701 Daegu, Korea

² Division of Advanced Research and Development, SINOKOR, 12 Seongseogongdanbuk-ro 43-gil, Dalseo-gu, Daegu 704-920, Korea

³ Division of Computer and Electronic Engineering, Pusan University of Foreign studies, 65 Namsan-dong, Geumjeong-gu, 608-738 Busan, Korea

⁴ Department of Electronics Engineering, Kyungil University, Hayang-up, Gyeongsang buk-do 712-702, Korea

Sensors 2017, 17(4), 856; https://doi.org/10.3390/s17040856 - 13 Apr 2017

Cited by 20 | Viewed by 7727

Abstract

In this study, we developed a pore size/pore area-controlled optical biosensor-based anodic aluminum oxide (AAO) nanostructure. As the pore size of AAO increases, the unit cell of AAO increases, which also increases the non-pore area to which the antibody binds. The increase in [...] Read more.

In this study, we developed a pore size/pore area-controlled optical biosensor-based anodic aluminum oxide (AAO) nanostructure. As the pore size of AAO increases, the unit cell of AAO increases, which also increases the non-pore area to which the antibody binds. The increase in the number of antibodies immobilized on the surface of the AAO enables effective detection of trace amounts of antigen, because increased antigen-antibody bonding results in a larger surface refractive index change. High sensitivity was thus achieved through amplification of the interference wave of two vertically-incident reflected waves through the localized surface plasmon resonance phenomenon. The sensitivity of the fabricated sensor was evaluated by measuring the change in wavelength with the change in the refractive index of the device surface, and sensitivity was increased with increasing pore-size and non-pore area. The sensitivity of the fabricated sensor was improved and up to 11.8 ag/mL serum amyloid A1 antigen was detected. In addition, the selectivity of the fabricated sensor was confirmed through a reaction with a heterogeneous substance, C-reactive protein antigen. By using hard anodization during fabrication of the AAO, the fabrication time of the device was reduced and the AAO chip was fabricated quickly and easily. Full article

(This article belongs to the Section Biosensors)

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13 pages, 8961 KiB

Open AccessArticle

Range Analysis of Thermal Stress and Optimal Design for Tungsten-Rhenium Thin Film Thermocouples Based on Ceramic Substrates

by Zhongkai Zhang, Bian Tian^*, Qiuyue Yu, Peng Shi, Qijing Lin, Na Zhao, Weixuan Jing and Zhuangde Jiang

State Key Laboratory for Mechanical Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(4), 857; https://doi.org/10.3390/s17040857 - 14 Apr 2017

Cited by 30 | Viewed by 6022

Abstract

A thermal stress range analysis of tungsten-rhenium thin film thermocouples based on ceramic substrates is presented to analyze the falling off and breakage problems caused by the mismatch of the thermal stresses in thin film thermocouples (TFTCs) and substrate, and nano-indentation experiments are [...] Read more.

A thermal stress range analysis of tungsten-rhenium thin film thermocouples based on ceramic substrates is presented to analyze the falling off and breakage problems caused by the mismatch of the thermal stresses in thin film thermocouples (TFTCs) and substrate, and nano-indentation experiments are done to measure and calculate the film stress to compare with the simulation results. Optimal design and fabrication of tungsten-rhenium TFTCs based on ceramic substrates is reported. Static high temperature tests are carried out, which show the optimization design can effectively reduce the damage caused by the thermal stress mismatch. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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30 pages, 5044 KiB

Open AccessArticle

Efficient Actor Recovery Paradigm for Wireless Sensor and Actor Networks

by Reem K. Mahjoub and Khaled Elleithy^*

Department of Computer Science, University of Bridgeport, 126 Park Avenue, Bridgeport, CT 06604, USA

Sensors 2017, 17(4), 858; https://doi.org/10.3390/s17040858 - 14 Apr 2017

Cited by 6 | Viewed by 5637

Abstract

The actor nodes are the spine of wireless sensor and actor networks (WSANs) that collaborate to perform a specific task in an unverified and uneven environment. Thus, there is a possibility of high failure rate in such unfriendly scenarios due to several factors [...] Read more.

The actor nodes are the spine of wireless sensor and actor networks (WSANs) that collaborate to perform a specific task in an unverified and uneven environment. Thus, there is a possibility of high failure rate in such unfriendly scenarios due to several factors such as power consumption of devices, electronic circuit failure, software errors in nodes or physical impairment of the actor nodes and inter-actor connectivity problem. Therefore, it is extremely important to discover the failure of a cut-vertex actor and network-disjoint in order to improve the Quality-of-Service (QoS). In this paper, we propose an Efficient Actor Recovery (EAR) paradigm to guarantee the contention-free traffic-forwarding capacity. The EAR paradigm consists of a Node Monitoring and Critical Node Detection (NMCND) algorithm that monitors the activities of the nodes to determine the critical node. In addition, it replaces the critical node with backup node prior to complete node-failure which helps balancing the network performance. The packets are handled using Network Integration and Message Forwarding (NIMF) algorithm that determines the source of forwarding the packets; either from actor or sensor. This decision-making capability of the algorithm controls the packet forwarding rate to maintain the network for a longer time. Furthermore, for handling the proper routing strategy, Priority-Based Routing for Node Failure Avoidance (PRNFA) algorithm is deployed to decide the priority of the packets to be forwarded based on the significance of information available in the packet. To validate the effectiveness of the proposed EAR paradigm, the proposed algorithms were tested using OMNET++ simulation. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 1665 KiB

Open AccessArticle

A Theoretical Study and Numerical Simulation of a Quasi-Distributed Sensor Based on the Low-Finesse Fabry-Perot Interferometer: Frequency-Division Multiplexing

by José Trinidad Guillen Bonilla^1,2,*, Alex Guillen Bonilla³, Verónica M. Rodríguez Betancourtt⁴, Héctor Guillen Bonilla⁴ and Antonio Casillas Zamora¹

¹ Computing and Electronic Departments, Centro Universitario de Ciencias Exactas e Ingenierías (CUCEI), University of Guadalajara, Blvd. M. García Barragán 1421, Guadalajara 44410, Jalisco, Mexico

² Mathematic Department, Centro Universitario de Ciencias Exactas e Ingenierías (CUCEI), University of Guadalajara, Blvd. M. García Barragán 1421, Guadalajara 44410, Jalisco, Mexico

³ Departamento de Ciencias Computacionales, Centro Universitario de los Valles, Universidad de Guadalajara, Ameca Km 45.5, Ameca C.P. 46600, Jalisco, Mexico

⁴ Materials Science Graduate School, Centro Universitario de Ciencias Exactas e Ingenierías (CUCEI), University of Guadalajara, Blvd. M. GarcíaBarragán 1421, Guadalajara 44410, Jalisco, Mexico

Sensors 2017, 17(4), 859; https://doi.org/10.3390/s17040859 - 14 Apr 2017

Cited by 9 | Viewed by 4994

Abstract

The application of the sensor optical fibers in the areas of scientific instrumentation and industrial instrumentation is very attractive due to its numerous advantages. In the industry of civil engineering for example, quasi-distributed sensors made with optical fiber are used for reliable strain [...] Read more.

The application of the sensor optical fibers in the areas of scientific instrumentation and industrial instrumentation is very attractive due to its numerous advantages. In the industry of civil engineering for example, quasi-distributed sensors made with optical fiber are used for reliable strain and temperature measurements. Here, a quasi-distributed sensor in the frequency domain is discussed. The sensor consists of a series of low-finesse Fabry-Perot interferometers where each Fabry-Perot interferometer acts as a local sensor. Fabry-Perot interferometers are formed by pairs of identical low reflective Bragg gratings imprinted in a single mode fiber. All interferometer sensors have different cavity length, provoking frequency-domain multiplexing. The optical signal represents the superposition of all interference patterns which can be decomposed using the Fourier transform. The frequency spectrum was analyzed and sensor’s properties were defined. Following that, a quasi-distributed sensor was numerically simulated. Our sensor simulation considers sensor properties, signal processing, noise system, and instrumentation. The numerical results show the behavior of resolution vs. signal-to-noise ratio. From our results, the Fabry-Perot sensor has high resolution and low resolution. Both resolutions are conceivable because the Fourier Domain Phase Analysis (FDPA) algorithm elaborates two evaluations of Bragg wavelength shift. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 4257 KiB

Open AccessArticle

Blockwise PPG Enhancement Based on Time-Variant Zero-Phase Harmonic Notch Filtering

by Chanki Park¹, Hyunsoon Shin² and Boreom Lee^3,*

¹ School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea

² Emotion Recognition IoT Research Section, Hyper-connected Communication Research Laboratory, Electronic and Telecommunications Research Institute (ETRI), Daejeon 34129, Korea

³ Department of Biomedical Science and Engineering (BMSE), Institute of Integrated Technology (IIT), Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea

Sensors 2017, 17(4), 860; https://doi.org/10.3390/s17040860 - 14 Apr 2017

Cited by 22 | Viewed by 6567

Abstract

So far, many approaches have been developed for motion artifact (MA) reduction from photoplethysmogram (PPG). Specifically, single-input MA reduction methods are useful to apply wearable and mobile healthcare systems because of their low hardware costs and simplicity. However, most of them are insufficiently [...] Read more.

So far, many approaches have been developed for motion artifact (MA) reduction from photoplethysmogram (PPG). Specifically, single-input MA reduction methods are useful to apply wearable and mobile healthcare systems because of their low hardware costs and simplicity. However, most of them are insufficiently developed to be used in real-world situations, and they suffer from a phase distortion problem. In this study, we propose a novel single-input MA reduction algorithm based on time-variant forward-backward harmonic notch filtering. To verify the proposed method, we collected real PPG data corrupted by MA and compared it with existing single-input MA reduction methods. In conclusion, the proposed zero-phase line enhancer (ZLE) was found to be superior for MA reduction and exhibited zero phase response. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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11 pages, 2380 KiB

Open AccessArticle

Electrochemical Detection of Dopamine Using 3D Porous Graphene Oxide/Gold Nanoparticle Composites

by Sung-Sik Choo^1,†, Ee-Seul Kang^1,†, Inbeom Song¹, Donghyun Lee¹, Jeong-Woo Choi² and Tae-Hyung Kim^1,*

¹ School of Integrative Engineering, Chung-Ang University, Seoul 06974, Korea

² Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 04109, Korea

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 861; https://doi.org/10.3390/s17040861 - 14 Apr 2017

Cited by 88 | Viewed by 11594

Abstract

The detection of dopamine in a highly sensitive and selective manner is crucial for the early diagnosis of a number of neurological diseases/disorders. Here, a report on a new platform for the electrochemical detection of dopamine with a considerable accuracy that comprises a [...] Read more.

The detection of dopamine in a highly sensitive and selective manner is crucial for the early diagnosis of a number of neurological diseases/disorders. Here, a report on a new platform for the electrochemical detection of dopamine with a considerable accuracy that comprises a 3D porous graphene oxide (pGO)/gold nanoparticle (GNP)/pGO composite-modified indium tin oxide (ITO) is presented. The pGO was first synthesized and purified by ultrasonication and centrifugation, and it was then further functionalized on the surface of a GNP-immobilized ITO electrode. Remarkably, owing to the synergistic effects of the pGO and GNPs, the 3D pGO-GNP-pGO-modified ITO electrode showed a superior dopamine-detection performance compared with the other pGO- or GNP-modified ITO electrodes. The linear range of the newly developed sensing platform is from 0.1 μM to 30 μM with a limit of detection (LOD) of 1.28 μM, which is more precise than the other previously reported GO-functionalized electrodes. Moreover, the 3D pGO-GNP-pGO-modified ITO electrodes maintained their detection capability even in the presence of several interfering molecules (e.g., ascorbic acid, glucose). The proposed platform of the 3D pGO-GNP-pGO-modified ITO electrode could therefore serve as a competent candidate for the development of a dopamine-sensing platform that is potentially applicable for the early diagnosis of various neurological diseases/disorders. Full article

(This article belongs to the Special Issue Micro and Nanofabrication Technologies for Biosensors)

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35 pages, 13990 KiB

Open AccessArticle

Fuzzy System-Based Target Selection for a NIR Camera-Based Gaze Tracker

by Rizwan Ali Naqvi, Muhammad Arsalan

and Kang Ryoung Park^*

Division of Electronics and Electrical Engineering, Dongguk University, 30 Pildong-ro 1-gil, Jung-gu, Seoul 100-715, Korea

Sensors 2017, 17(4), 862; https://doi.org/10.3390/s17040862 - 14 Apr 2017

Cited by 11 | Viewed by 6169

Abstract

Gaze-based interaction (GBI) techniques have been a popular subject of research in the last few decades. Among other applications, GBI can be used by persons with disabilities to perform everyday tasks, as a game interface, and can play a pivotal role in the [...] Read more.

Gaze-based interaction (GBI) techniques have been a popular subject of research in the last few decades. Among other applications, GBI can be used by persons with disabilities to perform everyday tasks, as a game interface, and can play a pivotal role in the human computer interface (HCI) field. While gaze tracking systems have shown high accuracy in GBI, detecting a user’s gaze for target selection is a challenging problem that needs to be considered while using a gaze detection system. Past research has used the blinking of the eyes for this purpose as well as dwell time-based methods, but these techniques are either inconvenient for the user or requires a long time for target selection. Therefore, in this paper, we propose a method for fuzzy system-based target selection for near-infrared (NIR) camera-based gaze trackers. The results of experiments performed in addition to tests of the usability and on-screen keyboard use of the proposed method show that it is better than previous methods. Full article

(This article belongs to the Special Issue Video Analysis and Tracking Using State-of-the-Art Sensors)

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16 pages, 4554 KiB

Open AccessArticle

The Modeling and Simulation of the Galvanic Coupling Intra-Body Communication via Handshake Channel

by Maoyuan Li, Yong Song^*, Wansong Li, Guangfa Wang, Tianpeng Bu, Yufei Zhao and Qun Hao

School of Optoelectronics, Beijing Institute of Technology, Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology, Beijing 100081, China

Sensors 2017, 17(4), 863; https://doi.org/10.3390/s17040863 - 14 Apr 2017

Cited by 11 | Viewed by 6954

Abstract

Intra-body communication (IBC) is a technology using the conductive properties of the body to transmit signal, and information interaction by handshake is regarded as one of the important applications of IBC. In this paper, a method for modeling the galvanic coupling intra-body communication [...] Read more.

Intra-body communication (IBC) is a technology using the conductive properties of the body to transmit signal, and information interaction by handshake is regarded as one of the important applications of IBC. In this paper, a method for modeling the galvanic coupling intra-body communication via handshake channel is proposed, while the corresponding parameters are discussed. Meanwhile, the mathematical model of this kind of IBC is developed. Finally, the validity of the developed model has been verified by measurements. Moreover, its characteristics are discussed and compared with that of the IBC via single body channel. Our results indicate that the proposed method will lay a foundation for the theoretical analysis and application of the IBC via handshake channel. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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16 pages, 564 KiB

Open AccessArticle

A Robust Crowdsourcing-Based Indoor Localization System

by Baoding Zhou^1,2

, Qingquan Li^1,2,*, Qingzhou Mao³ and Wei Tu^1,2,*

¹ Shenzhen Key Laboratory of Spatial Smart Sensing and Services, Shenzhen University, Shenzhen 518060, China

² Key Laboratory for Geo-Environment Monitoring of Coastal Zone of the National Administration of Surveying, Mapping and Geoinformation, Shenzhen University, Shenzhen 518060, China

³ State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China

Sensors 2017, 17(4), 864; https://doi.org/10.3390/s17040864 - 14 Apr 2017

Cited by 64 | Viewed by 6979

Abstract

WiFi fingerprinting-based indoor localization has been widely used due to its simplicity and can be implemented on the smartphones. The major drawback of WiFi fingerprinting is that the radio map construction is very labor-intensive and time-consuming. Another drawback of WiFi fingerprinting is the [...] Read more.

WiFi fingerprinting-based indoor localization has been widely used due to its simplicity and can be implemented on the smartphones. The major drawback of WiFi fingerprinting is that the radio map construction is very labor-intensive and time-consuming. Another drawback of WiFi fingerprinting is the Received Signal Strength (RSS) variance problem, caused by environmental changes and device diversity. RSS variance severely degrades the localization accuracy. In this paper, we propose a robust crowdsourcing-based indoor localization system (RCILS). RCILS can automatically construct the radio map using crowdsourcing data collected by smartphones. RCILS abstracts the indoor map as the semantics graph in which the edges are the possible user paths and the vertexes are the location where users may take special activities. RCILS extracts the activity sequence contained in the trajectories by activity detection and pedestrian dead-reckoning. Based on the semantics graph and activity sequence, crowdsourcing trajectories can be located and a radio map is constructed based on the localization results. For the RSS variance problem, RCILS uses the trajectory fingerprint model for indoor localization. During online localization, RCILS obtains an RSS sequence and realizes localization by matching the RSS sequence with the radio map. To evaluate RCILS, we apply RCILS in an office building. Experiment results demonstrate the efficiency and robustness of RCILS. Full article

(This article belongs to the Special Issue Smartphone-based Pedestrian Localization and Navigation)

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18 pages, 7985 KiB

Open AccessArticle

A 7.4 ps FPGA-Based TDC with a 1024-Unit Measurement Matrix

by Min Zhang¹

, Hai Wang^2,* and Yan Liu¹

¹ School of Electro-Mechanical Engineering, Xidian University, Xi’an 710071, China

² School of Aerospace Science and Technology, Xidian University, Xi’an 710071, China

Sensors 2017, 17(4), 865; https://doi.org/10.3390/s17040865 - 14 Apr 2017

Cited by 43 | Viewed by 9842

Abstract

In this paper, a high-resolution time-to-digital converter (TDC) based on a field programmable gate array (FPGA) device is proposed and tested. During the implementation, a new architecture of TDC is proposed which consists of a measurement matrix with 1024 units. The utilization of [...] Read more.

In this paper, a high-resolution time-to-digital converter (TDC) based on a field programmable gate array (FPGA) device is proposed and tested. During the implementation, a new architecture of TDC is proposed which consists of a measurement matrix with 1024 units. The utilization of routing resources as the delay elements distinguishes the proposed design from other existing designs, which contributes most to the device insensitivity to variations of temperature and voltage. Experimental results suggest that the measurement resolution is 7.4 ps, and the INL (integral nonlinearity) and DNL (differential nonlinearity) are 11.6 ps and 5.5 ps, which indicates that the proposed TDC offers high performance among the available TDCs. Benefitting from the FPGA platform, the proposed TDC has superiorities in easy implementation, low cost, and short development time. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 3653 KiB

Open AccessArticle

Low Power Near Field Communication Methods for RFID Applications of SIM Cards

by Yicheng Chen¹

, Zhaoxia Zheng², Mingyang Gong² and Fengqi Yu^1,*

¹ Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China

² School of Optical and Electronic Information, Huazhong University of Science & Technology, Wuhan 430074, China

Sensors 2017, 17(4), 867; https://doi.org/10.3390/s17040867 - 14 Apr 2017

Cited by 3 | Viewed by 6567

Abstract

Power consumption and communication distance have become crucial challenges for SIM card RFID (radio frequency identification) applications. The combination of long distance 2.45 GHz radio frequency (RF) technology and low power 2 kHz near distance communication is a workable scheme. In this paper, [...] Read more.

Power consumption and communication distance have become crucial challenges for SIM card RFID (radio frequency identification) applications. The combination of long distance 2.45 GHz radio frequency (RF) technology and low power 2 kHz near distance communication is a workable scheme. In this paper, an ultra-low frequency 2 kHz near field communication (NFC) method suitable for SIM cards is proposed and verified in silicon. The low frequency transmission model based on electromagnetic induction is discussed. Different transmission modes are introduced and compared, which show that the baseband transmit mode has a better performance. The low-pass filter circuit and programmable gain amplifiers are applied for noise reduction and signal amplitude amplification. Digital-to-analog converters and comparators are used to judge the card approach and departure. A novel differential Manchester decoder is proposed to deal with the internal clock drift in range-controlled communication applications. The chip has been fully implemented in 0.18 µm complementary metal-oxide-semiconductor (CMOS) technology, with a 330 µA work current and a 45 µA idle current. The low frequency chip can be integrated into a radio frequency SIM card for near field RFID applications. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 3771 KiB

Open AccessArticle

A Prosthetic Hand Body Area Controller Based on Efficient Pattern Recognition Control Strategies

by Simone Benatti^1,*

, Bojan Milosevic^2,*

, Elisabetta Farella²

, Emanuele Gruppioni³ and Luca Benini^1,4

¹ Micrel Lab, Unversity of Bologna, 40126 Bologna, Italy

² E3DA, Fondazione Bruno Kessler, 38123 Trento, Italy

³ Centro protesi INAIL, Vigorso di Budrio, 40054 Bologna, Italy

⁴ Integrated Systems Laboratory, ETHZ, 8092 Zurich, Switzerland

Sensors 2017, 17(4), 869; https://doi.org/10.3390/s17040869 - 15 Apr 2017

Cited by 56 | Viewed by 15905

Abstract

Poliarticulated prosthetic hands represent a powerful tool to restore functionality and improve quality of life for upper limb amputees. Such devices offer, on the same wearable node, sensing and actuation capabilities, which are not equally supported by natural interaction and control strategies. The [...] Read more.

Poliarticulated prosthetic hands represent a powerful tool to restore functionality and improve quality of life for upper limb amputees. Such devices offer, on the same wearable node, sensing and actuation capabilities, which are not equally supported by natural interaction and control strategies. The control in state-of-the-art solutions is still performed mainly through complex encoding of gestures in bursts of contractions of the residual forearm muscles, resulting in a non-intuitive Human-Machine Interface (HMI). Recent research efforts explore the use of myoelectric gesture recognition for innovative interaction solutions, however there persists a considerable gap between research evaluation and implementation into successful complete systems. In this paper, we present the design of a wearable prosthetic hand controller, based on intuitive gesture recognition and a custom control strategy. The wearable node directly actuates a poliarticulated hand and wirelessly interacts with a personal gateway (i.e., a smartphone) for the training and personalization of the recognition algorithm. Through the whole system development, we address the challenge of integrating an efficient embedded gesture classifier with a control strategy tailored for an intuitive interaction between the user and the prosthesis. We demonstrate that this combined approach outperforms systems based on mere pattern recognition, since they target the accuracy of a classification algorithm rather than the control of a gesture. The system was fully implemented, tested on healthy and amputee subjects and compared against benchmark repositories. The proposed approach achieves an error rate of 1.6% in the end-to-end real time control of commonly used hand gestures, while complying with the power and performance budget of a low-cost microcontroller. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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21 pages, 7446 KiB

Open AccessArticle

Visual Detection and Tracking System for a Spherical Amphibious Robot

by Shuxiang Guo^1,2, Shaowu Pan¹, Liwei Shi^1,*

, Ping Guo¹, Yanlin He¹ and Kun Tang¹

¹ Key Laboratory of Convergence Medical Engineering System and Healthcare Technology, the Ministry of Industry and Information Technology, School of Life Science, Beijing Institute of Technology, Beijing 100081, China

² Faculty of Engineering, Kagawa University, 2217-20 Hayashicho, Takamatsu, Kagawa 761-0396, Japan

Sensors 2017, 17(4), 870; https://doi.org/10.3390/s17040870 - 15 Apr 2017

Cited by 42 | Viewed by 7540

Abstract

With the goal of supporting close-range observation tasks of a spherical amphibious robot, such as ecological observations and intelligent surveillance, a moving target detection and tracking system was designed and implemented in this study. Given the restrictions presented by the amphibious environment and [...] Read more.

With the goal of supporting close-range observation tasks of a spherical amphibious robot, such as ecological observations and intelligent surveillance, a moving target detection and tracking system was designed and implemented in this study. Given the restrictions presented by the amphibious environment and the small-sized spherical amphibious robot, an industrial camera and vision algorithms using adaptive appearance models were adopted to construct the proposed system. To handle the problem of light scattering and absorption in the underwater environment, the multi-scale retinex with color restoration algorithm was used for image enhancement. Given the environmental disturbances in practical amphibious scenarios, the Gaussian mixture model was used to detect moving targets entering the field of view of the robot. A fast compressive tracker with a Kalman prediction mechanism was used to track the specified target. Considering the limited load space and the unique mechanical structure of the robot, the proposed vision system was fabricated with a low power system-on-chip using an asymmetric and heterogeneous computing architecture. Experimental results confirmed the validity and high efficiency of the proposed system. The design presented in this paper is able to meet future demands of spherical amphibious robots in biological monitoring and multi-robot cooperation. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 3218 KiB

Open AccessArticle

Using Dimensionality Reduction Techniques for Refining Passive Indoor Positioning Systems Based on Radio Fingerprinting

by Pedro E. Lopez-de-Teruel^†

, Oscar Canovas^*,†

and Felix J. Garcia^†

¹ Department of Computer Engineering, University of Murcia, 30100 Murcia, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 871; https://doi.org/10.3390/s17040871 - 15 Apr 2017

Cited by 15 | Viewed by 5281

Abstract

Indoor positioning methods based on fingerprinting and radio signals rely on the quality of the radio map. For example, for room-level classification purposes, it is required that the signal observations related to each room exhibit significant differences in their RSSI values. However, it [...] Read more.

Indoor positioning methods based on fingerprinting and radio signals rely on the quality of the radio map. For example, for room-level classification purposes, it is required that the signal observations related to each room exhibit significant differences in their RSSI values. However, it is difficult to verify and visualize that separability since radio maps are constituted by multi-dimensional observations whose dimension is directly related to the number of access points or monitors being employed for localization purposes. In this paper, we propose a refinement cycle for passive indoor positioning systems, which is based on dimensionality reduction techniques, to evaluate the quality of a radio map. By means of these techniques and our own data representation, we have defined two different visualization methods to obtain graphical information about the quality of a particular radio map in terms of overlapping areas and outliers. That information will be useful to determine whether new monitors are required or some existing ones should be moved. We have performed an exhaustive experimental analysis based on a variety of different scenarios, some deployed by our own research group and others corresponding to a well-known existing dataset widely analyzed by the community, in order to validate our proposal. As we will show, among the different combinations of data representation methods and dimensionality reduction techniques that we discuss, we have found that there are some specific configurations that are more useful in order to perform the refinement process. Full article

(This article belongs to the Special Issue Sensors and Sensing in Indoor Localization, Tracking, Navigation and Activity Monitoring)

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16 pages, 7012 KiB

Open AccessArticle

A Smart Voltage and Current Monitoring System for Three Phase Inverters Using an Android Smartphone Application

by Mohannad Jabbar Mnati^1,2,*, Alex Van den Bossche^1,3

and Raad Farhood Chisab⁴

¹ Department of Electrical Energy, Metals, Mechanical Constructions and Systems, Ghent University, Technologiepark Zwijnaarde 913, B-9052 Zwijnaarde, Gent, Belgium

² Department of Electronic Technology, Institute of Technology Baghdad, Middle Technical University, Al-Za’franiya, 10074 Baghdad, Iraq

³ Flanders Make, the Strategic Research Centre for the Manufacturing Industry, B-8500 Kortrijk, Belgium

⁴ Department of Electrical Technology, Technical Institute Kut, Middle Technical University, Al-Za’franiya, 10074 Baghdad, Iraq

Sensors 2017, 17(4), 872; https://doi.org/10.3390/s17040872 - 15 Apr 2017

Cited by 86 | Viewed by 27454

Abstract

In this paper, a new smart voltage and current monitoring system (SVCMS) technique is proposed. It monitors a three phase electrical system using an Arduino platform as a microcontroller to read the voltage and current from sensors and then wirelessly send the measured [...] Read more.

In this paper, a new smart voltage and current monitoring system (SVCMS) technique is proposed. It monitors a three phase electrical system using an Arduino platform as a microcontroller to read the voltage and current from sensors and then wirelessly send the measured data to monitor the results using a new Android application. The integrated SVCMS design uses an Arduino Nano V3.0 as the microcontroller to measure the results from three voltage and three current sensors and then send this data, after calculation, to the Android smartphone device of an end user using Bluetooth HC-05. The Arduino Nano V3.0 controller and Bluetooth HC-05 are a cheap microcontroller and wireless device, respectively. The new Android smartphone application that monitors the voltage and current measurements uses the open source MIT App Inventor 2 software. It allows for monitoring some elementary fundamental voltage power quality properties. An effort has been made to investigate what is possible using available off-the-shelf components and open source software. Full article

(This article belongs to the Special Issue Systems and Software for Low Power Embedded Sensing)

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14 pages, 1057 KiB

Open AccessArticle

Cross-Spectral Local Descriptors via Quadruplet Network

by Cristhian A. Aguilera^1,2,*, Angel D. Sappa^1,3, Cristhian Aguilera⁴ and Ricardo Toledo^1,2

¹ Computer Vision Center, Edifici O, Campus UAB, Bellaterra 08193, Barcelona, Spain

² Computer Science Department, Universitat Autònoma de Barcelona, Campus UAB, Bellaterra 08193,Barcelona, Spain

³ Facultad de Ingeniería en Electricidad y Computación, CIDIS, Escuela Superior Politécnica del Litoral,ESPOL, Campus Gustavo Galindo, Km 30.5 vía Perimetral, Guayaquil 09-01-5863, Ecuador

⁴ DIEE, University of Bío-Bío, Concepción 4051381, Concepción, Chile

Sensors 2017, 17(4), 873; https://doi.org/10.3390/s17040873 - 15 Apr 2017

Cited by 36 | Viewed by 5927

Abstract

This paper presents a novel CNN-based architecture, referred to as Q-Net, to learn local feature descriptors that are useful for matching image patches from two different spectral bands. Given correctly matched and non-matching cross-spectral image pairs, a quadruplet network is trained to map [...] Read more.

This paper presents a novel CNN-based architecture, referred to as Q-Net, to learn local feature descriptors that are useful for matching image patches from two different spectral bands. Given correctly matched and non-matching cross-spectral image pairs, a quadruplet network is trained to map input image patches to a common Euclidean space, regardless of the input spectral band. Our approach is inspired by the recent success of triplet networks in the visible spectrum, but adapted for cross-spectral scenarios, where, for each matching pair, there are always two possible non-matching patches: one for each spectrum. Experimental evaluations on a public cross-spectral VIS-NIR dataset shows that the proposed approach improves the state-of-the-art. Moreover, the proposed technique can also be used in mono-spectral settings, obtaining a similar performance to triplet network descriptors, but requiring less training data. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 8586 KiB

Open AccessArticle

A Strain-Based Method to Estimate Slip Angle and Tire Working Conditions for Intelligent Tires Using Fuzzy Logic

by Daniel Garcia-Pozuelo¹, Jorge Yunta^1,*, Oluremi Olatunbosun²

, Xiaoguang Yang³ and Vicente Diaz¹

¹ Mechanical Engineering Department, Universidad Carlos III de Madrid, Avd. De la Universidad, Madrid 28911, Spain

² School of Mechanical Engineering, University of Birmingham, Edgbaston B15 2TT, UK

³ Vanlead Rubber & Tire Research Institute, Wanli Tire Corporation Limited, Guangzhou 510425, China

Sensors 2017, 17(4), 874; https://doi.org/10.3390/s17040874 - 16 Apr 2017

Cited by 49 | Viewed by 8124

Abstract

Tires equipped with sensors, the so-called “intelligent tires”, can provide vital information for control systems, drivers and external users. In this research, tire dynamic strain characteristics in cornering conditions are collected and analysed in relation to the variation of tire working conditions, such [...] Read more.

Tires equipped with sensors, the so-called “intelligent tires”, can provide vital information for control systems, drivers and external users. In this research, tire dynamic strain characteristics in cornering conditions are collected and analysed in relation to the variation of tire working conditions, such as inflation pressure, rolling speed, vertical load and slip angle. An experimental tire strain-based prototype and an indoor tire test rig are used to demonstrate the suitability of strain sensors to establish relations between strain data and lateral force. The results of experiments show that strain values drop sharply when lateral force is decreasing, which can be used to predict tire slip conditions. As a first approach to estimate some tire working conditions, such as the slip angle and vertical load, a fuzzy logic method has been developed. The simulation and test results confirm the feasibility of strain sensors and the proposed computational model to solve the non-linearity characteristics of the tires’ parameters and turn tires into a source of useful information. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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12 pages, 5493 KiB

Open AccessArticle

Intelligent Medical Garments with Graphene-Functionalized Smart-Cloth ECG Sensors

by Murat Kaya Yapici^1,2,3,*

and Tamador Elboshra Alkhidir⁴

¹ Faculty of Engineering and Natural Sciences, Sabancı University, Istanbul 34956, Turkey

² Sabancı University Nanotechnology Research and Application Center, Istanbul 34956, Turkey

³ Department of Electrical Engineering, University of Washington, Seattle, WA 98195, USA

⁴ Department of Electrical and Computer Engineering, Khalifa University, Abu Dhabi 127788, UAE

Sensors 2017, 17(4), 875; https://doi.org/10.3390/s17040875 - 16 Apr 2017

Cited by 139 | Viewed by 15066

Abstract

Biopotential signals are recorded mostly by using sticky, pre-gelled electrodes, which are not ideal for wearable, point-of-care monitoring where the usability of the personalized medical device depends critically on the level of comfort and wearability of the electrodes. We report a fully-wearable medical [...] Read more.

Biopotential signals are recorded mostly by using sticky, pre-gelled electrodes, which are not ideal for wearable, point-of-care monitoring where the usability of the personalized medical device depends critically on the level of comfort and wearability of the electrodes. We report a fully-wearable medical garment for mobile monitoring of cardiac biopotentials from the wrists or the neck with minimum restriction to regular clothing habits. The wearable prototype is based on elastic bands with graphene functionalized, textile electrodes and battery-powered, low-cost electronics for signal acquisition and wireless transmission. Comparison of the electrocardiogram (ECG) recordings obtained from the wearable prototype against conventional wet electrodes indicate excellent conformity and spectral coherence among the two signals. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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21 pages, 3460 KiB

Open AccessArticle

New Compact 3-Dimensional Shape Descriptor for a Depth Camera in Indoor Environments

by Hyukdoo Choi^1,2 and Euntai Kim^1,*

¹ School of Electrical & Electronic Engineering, Yonsei University, Seoul 03722, Korea

² LG Electronics, Seoul 08592, Korea

Sensors 2017, 17(4), 876; https://doi.org/10.3390/s17040876 - 16 Apr 2017

Viewed by 3961

Abstract

This study questions why existing local shape descriptors have high dimensionalities (up to hundreds) despite simplicity of local shapes. We derived an answer from a historical context and provided an alternative solution by proposing a new compact descriptor. Although existing descriptors can express [...] Read more.

This study questions why existing local shape descriptors have high dimensionalities (up to hundreds) despite simplicity of local shapes. We derived an answer from a historical context and provided an alternative solution by proposing a new compact descriptor. Although existing descriptors can express complicated shapes and depth sensors have been improved, complex shapes are rarely observed in an ordinary environment and a depth sensor only captures a single side of a surface with noise. Therefore, we designed a new descriptor based on principal curvatures, which is compact but practically useful. For verification, the CoRBS dataset, the RGB-D Scenes dataset and the RGB-D Object dataset were used to compare the proposed descriptor with existing descriptors in terms of shape, instance, and category recognition rate. The proposed descriptor showed a comparable performance with existing descriptors despite its low dimensionality of 4. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 4410 KiB

Open AccessFeature PaperArticle

Out-of-Plane Continuous Electrostatic Micro-Power Generators

by M. A. E. Mahmoud^1,*, E. M. Abdel-Rahman²

, R. R. Mansour³ and E. F. El-Saadany³

¹ Department of Electrical and Computer Engineering, Ain Shams University, 1156 Cairo, Egypt

² Department of Systems Design Engineering, University of Waterloo, Waterloo, N2L 3G1 ON, Canada

³ Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, N2L 3G1 ON, Canada

Sensors 2017, 17(4), 877; https://doi.org/10.3390/s17040877 - 16 Apr 2017

Cited by 11 | Viewed by 5076

Abstract

This paper presents an out-of-plane electrostatic micro-power generator (MPG). Electret-based continuous MPGs with different gaps and masses are fabricated to demonstrate the merits of this topology. Experimental results of the MPG demonstrate output power of 1 mW for a base acceleration amplitude and [...] Read more.

This paper presents an out-of-plane electrostatic micro-power generator (MPG). Electret-based continuous MPGs with different gaps and masses are fabricated to demonstrate the merits of this topology. Experimental results of the MPG demonstrate output power of 1 mW for a base acceleration amplitude and frequency of 0.08 g and 86 Hz. The MPGs also demonstrate a wideband harvesting bandwidth reaching up to 9 Hz. A free-flight and an impact mode model of electrostatic MPGs are also derived and validated by comparison to experimental results. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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12 pages, 8167 KiB

Open AccessFeature PaperArticle

Measurement of Pressure Fluctuations inside a Model Thrust Bearing Using PVDF Sensors

by Andrew Youssef^†, David Matthews^†, Andrew Guzzomi^† and Jie Pan^*,†

¹ School of Mechanical and Chemical Engineering, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 878; https://doi.org/10.3390/s17040878 - 16 Apr 2017

Cited by 12 | Viewed by 6055

Abstract

Thrust bearings play a vital role in propulsion systems. They rely on a thin layer of oil being trapped between rotating surfaces to produce a low friction interface. The “quality” of this bearing affects many things from noise transmission to the ultimate catastrophic [...] Read more.

Thrust bearings play a vital role in propulsion systems. They rely on a thin layer of oil being trapped between rotating surfaces to produce a low friction interface. The “quality” of this bearing affects many things from noise transmission to the ultimate catastrophic failure of the bearing itself. As a result, the direct measure of the forces and vibrations within the oil filled interface would be very desirable and would give an indication of the condition of the bearing in situ. The thickness of the oil film is, however, very small and conventional vibration sensors are too cumbersome to use in this confined space. This paper solves this problem by using a piezoelectric polymer film made from Polyvinylidine Fluoride (PVDF). These films are very thin (50 m) and flexible and easy to install in awkward spaces such as the inside of a thrust bearing. A model thrust bearing was constructed using a 3D printer and PVDF films inserted into the base of the bearing. In doing so, it was possible to directly measure the force fluctuations due to the rotating pads and investigate various properties of the thrust bearing itself. Full article

(This article belongs to the Special Issue 3D Printed Sensors)

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21 pages, 13789 KiB

Open AccessArticle

Device-Free Localization via an Extreme Learning Machine with Parameterized Geometrical Feature Extraction

by Jie Zhang¹, Wendong Xiao¹, Sen Zhang^1,*

and Shoudong Huang²

¹ School of Automation & Electrical Engineering, University of Science and Technology Beijing, Beijing 100083, China

² Centre for Autonomous Systems, Faculty of Engineering and Information Technology, University of Technology Sydney, Ultimo, NSW 2007, Australia

Sensors 2017, 17(4), 879; https://doi.org/10.3390/s17040879 - 17 Apr 2017

Cited by 48 | Viewed by 6659

Abstract

Device-free localization (DFL) is becoming one of the new technologies in wireless localization field, due to its advantage that the target to be localized does not need to be attached to any electronic device. In the radio-frequency (RF) DFL system, radio transmitters (RTs) [...] Read more.

Device-free localization (DFL) is becoming one of the new technologies in wireless localization field, due to its advantage that the target to be localized does not need to be attached to any electronic device. In the radio-frequency (RF) DFL system, radio transmitters (RTs) and radio receivers (RXs) are used to sense the target collaboratively, and the location of the target can be estimated by fusing the changes of the received signal strength (RSS) measurements associated with the wireless links. In this paper, we will propose an extreme learning machine (ELM) approach for DFL, to improve the efficiency and the accuracy of the localization algorithm. Different from the conventional machine learning approaches for wireless localization, in which the above differential RSS measurements are trivially used as the only input features, we introduce the parameterized geometrical representation for an affected link, which consists of its geometrical intercepts and differential RSS measurement. Parameterized geometrical feature extraction (PGFE) is performed for the affected links and the features are used as the inputs of ELM. The proposed PGFE-ELM for DFL is trained in the offline phase and performed for real-time localization in the online phase, where the estimated location of the target is obtained through the created ELM. PGFE-ELM has the advantages that the affected links used by ELM in the online phase can be different from those used for training in the offline phase, and can be more robust to deal with the uncertain combination of the detectable wireless links. Experimental results show that the proposed PGFE-ELM can improve the localization accuracy and learning speed significantly compared with a number of the existing machine learning and DFL approaches, including the weighted K-nearest neighbor (WKNN), support vector machine (SVM), back propagation neural network (BPNN), as well as the well-known radio tomographic imaging (RTI) DFL approach. Full article

(This article belongs to the Special Issue Sensors and Analytics for Precision Medicine)

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14 pages, 5332 KiB

Open AccessArticle

A New Input Device for Spastics Based on Strain Gauge

by Niels Buchhold^* and Christian Baumgartner^*

Institute of Health Care Engineering with European Testing and Certification Body of Medical Devices, Graz University of Technology, Stremayrgasse 16/II, 8010 Graz, Austria

Sensors 2017, 17(4), 880; https://doi.org/10.3390/s17040880 - 17 Apr 2017

Cited by 1 | Viewed by 4680

Abstract

This article presents a new sensor for use by people with spastic disorders and similar conditions and enables them to steer and control medical devices such as electric powered wheelchairs. As spastic patients often suffer from cramping of their extremities, which can then [...] Read more.

This article presents a new sensor for use by people with spastic disorders and similar conditions and enables them to steer and control medical devices such as electric powered wheelchairs. As spastic patients often suffer from cramping of their extremities, which can then no longer be controlled, using a standard joystick while operating a powered wheelchair can lead to dangerous situations. To prevent this, we designed a sensor based on strain gauges, which is shaped like a flat disc that can be operated using any body part. By shifting weight along the x- and y-axis, the disc tilts in all directions thereby generating proportionate output signals. The disc can also be pressed downward (z-axis), for example, to open a wheelchair’s menu. Thanks to the sensor’s flat disc-like construction and the option of mounting it into a control panel, users are not in danger of becoming stuck on the disc during spastic episodes. In the event of a spasm, body parts simply slide over the disc reducing risk of unintended actions. The sensor is adaptive and adjustable enabling it to fit a user’s range of strength and motion at any time. It was developed to ensure users can operate sensitive systems safely. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 2150 KiB

Open AccessArticle

A Quantitative PCR-Electrochemical Genosensor Test for the Screening of Biotech Crops

by Suely Moura-Melo^1,2, Rebeca Miranda-Castro¹

, Noemí De-los-Santos-Álvarez¹

, Arturo J. Miranda-Ordieres¹, José Ribeiro Dos Santos Junior², Rosana A. Da Silva Fonseca³ and María Jesús Lobo-Castañón^1,*

¹ Departamento de Química Física y Analítica, Universidad de Oviedo, 33006 Oviedo, Spain

² Departamento de Química, Centro de Ciências da Natureza, Universidade Federal do Piauí, Teresina 64049-550PI, Brazil

³ Instituto de Ciencias Biológicas, Universidade de Pernambuco, Recife 50670-901PE, Brazil

Sensors 2017, 17(4), 881; https://doi.org/10.3390/s17040881 - 18 Apr 2017

Cited by 9 | Viewed by 6747

Abstract

The design of screening methods for the detection of genetically modified organisms (GMOs) in food would improve the efficiency in their control. We report here a PCR amplification method combined with a sequence-specific electrochemical genosensor for the quantification of a DNA sequence characteristic [...] Read more.

The design of screening methods for the detection of genetically modified organisms (GMOs) in food would improve the efficiency in their control. We report here a PCR amplification method combined with a sequence-specific electrochemical genosensor for the quantification of a DNA sequence characteristic of the 35S promoter derived from the cauliflower mosaic virus (CaMV). Specifically, we employ a genosensor constructed by chemisorption of a thiolated capture probe and p-aminothiophenol gold surfaces to entrap on the sensing layer the unpurified PCR amplicons, together with a signaling probe labeled with fluorescein. The proposed test allows for the determination of a transgene copy number in both hemizygous (maize MON810 trait) and homozygous (soybean GTS40-3-2) transformed plants, and exhibits a limit of quantification of at least 0.25% for both kinds of GMO lines. Full article

(This article belongs to the Special Issue Genosensing)

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16 pages, 4019 KiB

Open AccessArticle

Carbon Nanotube-Based Chemiresistive Sensors

by Ruixian Tang^†, Yongji Shi^†, Zhongyu Hou and Liangming Wei^*

¹ Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 882; https://doi.org/10.3390/s17040882 - 18 Apr 2017

Cited by 160 | Viewed by 14553

Abstract

The development of simple and low-cost chemical sensors is critically important for improving human life. Many types of chemical sensors have been developed. Among them, the chemiresistive sensors receive particular attention because of their simple structure, the ease of high precise measurement and [...] Read more.

The development of simple and low-cost chemical sensors is critically important for improving human life. Many types of chemical sensors have been developed. Among them, the chemiresistive sensors receive particular attention because of their simple structure, the ease of high precise measurement and the low cost. This review mainly focuses on carbon nanotube (CNT)-based chemiresistive sensors. We first describe the properties of CNTs and the structure of CNT chemiresistive sensors. Next, the sensing mechanism and the performance parameters of the sensors are discussed. Then, we detail the status of the CNT chemiresistive sensors for detection of different analytes. Lastly, we put forward the remaining challenges for CNT chemiresistive sensors and outlook the possible opportunity for CNT chemiresistive sensors in the future. Full article

(This article belongs to the Special Issue Chemiresistive Sensors: Status and the Future)

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19 pages, 1608 KiB

Open AccessArticle

Multiple Objects Fusion Tracker Using a Matching Network for Adaptively Represented Instance Pairs

by Sang-Il Oh

and Hang-Bong Kang^*

Department of Media Engineering, Catholic University of Korea, 43-1, Yeoggok 2-dong, Wonmmi-gu, Bucheon-si, Gyeonggi-do 14662, Korea

Sensors 2017, 17(4), 883; https://doi.org/10.3390/s17040883 - 18 Apr 2017

Cited by 4 | Viewed by 5867

Abstract

Multiple-object tracking is affected by various sources of distortion, such as occlusion, illumination variations and motion changes. Overcoming these distortions by tracking on RGB frames, such as shifting, has limitations because of material distortions caused by RGB frames. To overcome these distortions, we [...] Read more.

Multiple-object tracking is affected by various sources of distortion, such as occlusion, illumination variations and motion changes. Overcoming these distortions by tracking on RGB frames, such as shifting, has limitations because of material distortions caused by RGB frames. To overcome these distortions, we propose a multiple-object fusion tracker (MOFT), which uses a combination of 3D point clouds and corresponding RGB frames. The MOFT uses a matching function initialized on large-scale external sequences to determine which candidates in the current frame match with the target object in the previous frame. After conducting tracking on a few frames, the initialized matching function is fine-tuned according to the appearance models of target objects. The fine-tuning process of the matching function is constructed as a structured form with diverse matching function branches. In general multiple object tracking situations, scale variations for a scene occur depending on the distance between the target objects and the sensors. If the target objects in various scales are equally represented with the same strategy, information losses will occur for any representation of the target objects. In this paper, the output map of the convolutional layer obtained from a pre-trained convolutional neural network is used to adaptively represent instances without information loss. In addition, MOFT fuses the tracking results obtained from each modality at the decision level to compensate the tracking failures of each modality using basic belief assignment, rather than fusing modalities by selectively using the features of each modality. Experimental results indicate that the proposed tracker provides state-of-the-art performance considering multiple objects tracking (MOT) and KITTIbenchmarks. Full article

(This article belongs to the Special Issue Sensors for Transportation)

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9 pages, 3901 KiB

Open AccessArticle

Probe Sensor Using Nanostructured Multi-Walled Carbon Nanotube Yarn for Selective and Sensitive Detection of Dopamine

by Wed Al-Graiti^1,2, Zhilian Yue¹, Javad Foroughi^1,*

, Xu-Feng Huang³, Gordon Wallace¹, Ray Baughman⁴ and Jun Chen^1,*

¹ ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM, University of Wollongong, Wollongong, NSW 2522, Australia

² Department of Chemistry, Faculty of Science, Thi-Qar University, Thi-Qar, 64001, Iraq

³ Centre for Translational Neuroscience, IHMRI, School of Health Sciences, University of Wollongong, Wollongong, NSW 2522, Australia

⁴ The Alan G.MacDiarmid NanoTech Institute and Department of Chemistry, University of Texas at Dallas, Richardson, TX 75083, USA

Sensors 2017, 17(4), 884; https://doi.org/10.3390/s17040884 - 18 Apr 2017

Cited by 37 | Viewed by 7095

Abstract

The demands for electrochemical sensor materials with high strength and durability in physiological conditions continue to grow and novel approaches are being enabled by the advent of new electromaterials and novel fabrication technologies. Herein, we demonstrate a probe-style electrochemical sensor using highly flexible [...] Read more.

The demands for electrochemical sensor materials with high strength and durability in physiological conditions continue to grow and novel approaches are being enabled by the advent of new electromaterials and novel fabrication technologies. Herein, we demonstrate a probe-style electrochemical sensor using highly flexible and conductive multi-walled carbon nanotubes (MWNT) yarns. The MWNT yarn-based sensors can be fabricated onto micro Pt-wire with a controlled diameter varying from 100 to 300 µm, and then further modified with Nafion via a dip-coating approach. The fabricated micro-sized sensors were characterized by electron microscopy, Raman, FTIR, electrical, and electrochemical measurements. For the first time, the MWNT/Nafion yarn-based probe sensors have been assembled and assessed for high-performance dopamine sensing, showing a significant improvement in both sensitivity and selectivity in dopamine detection in presence of ascorbic acid and uric acid. It offers the potential to be further developed as implantable probe sensors. Full article

(This article belongs to the Special Issue Whole Cell-Based Biosensors and Application)

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9 pages, 4290 KiB

Open AccessArticle

Detecting Single-Nucleotides by Tunneling Current Measurements at Sub-MHz Temporal Resolution

by Takanori Morikawa, Kazumichi Yokota, Sachie Tanimoto, Makusu Tsutsui^* and Masateru Taniguchi

The Institute of Scientific and Industrial Research, Osaka University, 8‐1 Mihogaoka, Ibaraki 567-0047, Japan

Sensors 2017, 17(4), 885; https://doi.org/10.3390/s17040885 - 18 Apr 2017

Cited by 7 | Viewed by 5170

Abstract

Label-free detection of single-nucleotides was performed by fast tunneling current measurements in a polar solvent at 1 MHz sampling rate using SiO₂-protected Au nanoprobes. Short current spikes were observed, suggestive of trapping/detrapping of individual nucleotides between the nanoelectrodes. The fall and [...] Read more.

Label-free detection of single-nucleotides was performed by fast tunneling current measurements in a polar solvent at 1 MHz sampling rate using SiO₂-protected Au nanoprobes. Short current spikes were observed, suggestive of trapping/detrapping of individual nucleotides between the nanoelectrodes. The fall and rise features of the electrical signatures indicated signal retardation by capacitance effects with a time constant of about 10 microseconds. The high temporal resolution revealed current fluctuations, reflecting the molecular conformation degrees of freedom in the electrode gap. The method presented in this work may enable direct characterizations of dynamic changes in single-molecule conformations in an electrode gap in liquid. Full article

(This article belongs to the Special Issue Single-Molecule Sensing)

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11 pages, 7113 KiB

Open AccessArticle

A Novel Auto-Sorting System for Chinese Cabbage Seeds

by Kuo-Yi Huang^* and Jian-Feng Cheng

Department of Bio-Industrial Mechatronics Engineering, National Chung Hsing University, Tai-Chung 402, Taiwan

Sensors 2017, 17(4), 886; https://doi.org/10.3390/s17040886 - 18 Apr 2017

Cited by 23 | Viewed by 5968

Abstract

This paper presents a novel machine vision-based auto-sorting system for Chinese cabbage seeds. The system comprises an inlet-outlet mechanism, machine vision hardware and software, and control system for sorting seed quality. The proposed method can estimate the shape, color, and textural features of [...] Read more.

This paper presents a novel machine vision-based auto-sorting system for Chinese cabbage seeds. The system comprises an inlet-outlet mechanism, machine vision hardware and software, and control system for sorting seed quality. The proposed method can estimate the shape, color, and textural features of seeds that are provided as input neurons of neural networks in order to classify seeds as “good” and “not good” (NG). The results show the accuracies of classification to be 91.53% and 88.95% for good and NG seeds, respectively. The experimental results indicate that Chinese cabbage seeds can be sorted efficiently using the developed system. Full article

(This article belongs to the Special Issue Innovative Sensing Control Scheme for Advanced Materials)

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19 pages, 3447 KiB

Open AccessArticle

Multi-Mode Estimation for Small Fixed Wing Unmanned Aerial Vehicle Localization Based on a Linear Matrix Inequality Approach

by Mostafa Elzoghby^1,*

, Fu Li¹, Ibrahim. I. Arafa² and Usman Arif¹

¹ School of Automation Science and Electrical Engineering, Beihang University, 37 Xueyuan Road, Haidian District, Beijing 100191, China

² School of Control and Automation, MTC, Al-Khalifa Al-Maamoon Street Kobry Elkobbah, Cairo 11331, Egypt

Sensors 2017, 17(4), 887; https://doi.org/10.3390/s17040887 - 18 Apr 2017

Cited by 4 | Viewed by 3843

Abstract

Information fusion from multiple sensors ensures the accuracy and robustness of a navigation system, especially in the absence of global positioning system (GPS) data which gets degraded in many cases. A way to deal with multi-mode estimation for a small fixed wing unmanned [...] Read more.

Information fusion from multiple sensors ensures the accuracy and robustness of a navigation system, especially in the absence of global positioning system (GPS) data which gets degraded in many cases. A way to deal with multi-mode estimation for a small fixed wing unmanned aerial vehicle (UAV) localization framework is proposed, which depends on utilizing a Luenberger observer-based linear matrix inequality (LMI) approach. The proposed estimation technique relies on the interaction between multiple measurement modes and a continuous observer. The state estimation is performed in a switching environment between multiple active sensors to exploit the available information as much as possible, especially in GPS-denied environments. Luenberger observer-based projection is implemented as a continuous observer to optimize the estimation performance. The observer gain might be chosen by solving a Lyapunov equation by means of a LMI algorithm. Convergence is achieved by utilizing the linear matrix inequality (LMI), based on Lyapunov stability which keeps the dynamic estimation error bounded by selecting the observer gain matrix (L). Simulation results are presented for a small UAV fixed wing localization problem. The results obtained using the proposed approach are compared with a single mode Extended Kalman Filter (EKF). Simulation results are presented to demonstrate the viability of the proposed strategy. Full article

(This article belongs to the Section Remote Sensors)

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27 pages, 15871 KiB

Open AccessArticle

A Latency and Coverage Optimized Data Collection Scheme for Smart Cities Based on Vehicular Ad-hoc Networks

by Yixuan Xu¹, Xi Chen¹, Anfeng Liu¹

and Chunhua Hu^2,3,*

¹ School of Information Science and Engineering, Central South University, Changsha 410083, China

² Key Laboratory of Hunan Province for Mobile Business Intelligence, Hunan University of Commerce, Changsha 410205, China

³ Mobile E-business Collaborative Innovation Center of Hunan Province, Hunan University of Commerce, Changsha 410205, China

Sensors 2017, 17(4), 888; https://doi.org/10.3390/s17040888 - 18 Apr 2017

Cited by 35 | Viewed by 6734

Abstract

Using mobile vehicles as “data mules” to collect data generated by a huge number of sensing devices that are widely spread across smart city is considered to be an economical and effective way of obtaining data about smart cities. However, currently most research [...] Read more.

Using mobile vehicles as “data mules” to collect data generated by a huge number of sensing devices that are widely spread across smart city is considered to be an economical and effective way of obtaining data about smart cities. However, currently most research focuses on the feasibility of the proposed methods instead of their final performance. In this paper, a latency and coverage optimized data collection (LCODC) scheme is proposed to collect data on smart cities through opportunistic routing. Compared with other schemes, the efficiency of data collection is improved since the data flow in LCODC scheme consists of not only vehicle to device transmission (V2D), but also vehicle to vehicle transmission (V2V). Besides, through data mining on patterns hidden in the smart city, waste and redundancy in the utilization of public resources are mitigated, leading to the easy implementation of our scheme. In detail, no extra supporting device is needed in the LCODC scheme to facilitate data transmission. A large-scale and real-world dataset on Beijing is used to evaluate the LCODC scheme. Results indicate that with very limited costs, the LCODC scheme enables the average latency to decrease from several hours to around 12 min with respect to schemes where V2V transmission is disabled while the coverage rate is able to reach over 30%. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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8 pages, 12766 KiB

Open AccessArticle

Integrated Flexible Electronic Devices Based on Passive Alignment for Physiological Measurement

by Jin Hwa Ryu^1,†

, Sangwon Byun^2,†, In-Bok Baek^1,†, Bong Kuk Lee¹, Won Ick Jang¹, Eun-Hye Jang¹, Ah-Yung Kim¹ and Han Yung Yu^1,*

¹ Bio-Medical IT Convergence Research Division, Electronics and Telecommunications Research Institute (ETRI), Daejeon 34129, Korea

² Department of Electronics Engineering, Incheon National University, Incheon 22012, Korea

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 889; https://doi.org/10.3390/s17040889 - 18 Apr 2017

Cited by 1 | Viewed by 6746

Abstract

This study proposes a simple method of fabricating flexible electronic devices using a metal template for passive alignment between chip components and an interconnect layer, which enabled efficient alignment with high accuracy. An electrocardiogram (ECG) sensor was fabricated using 20 µm thick polyimide [...] Read more.

This study proposes a simple method of fabricating flexible electronic devices using a metal template for passive alignment between chip components and an interconnect layer, which enabled efficient alignment with high accuracy. An electrocardiogram (ECG) sensor was fabricated using 20 µm thick polyimide (PI) film as a flexible substrate to demonstrate the feasibility of the proposed method. The interconnect layer was fabricated by a two-step photolithography process and evaporation. After applying solder paste, the metal template was placed on top of the interconnect layer. The metal template had rectangular holes at the same position as the chip components on the interconnect layer. Rectangular hole sizes were designed to account for alignment tolerance of the chips. Passive alignment was performed by simply inserting the components in the holes of the template, which resulted in accurate alignment with positional tolerance of less than 10 µm based on the structural design, suggesting that our method can efficiently perform chip mounting with precision. Furthermore, a fabricated flexible ECG sensor was easily attachable to the curved skin surface and able to measure ECG signals from a human subject. These results suggest that the proposed method can be used to fabricate epidermal sensors, which are mounted on the skin to measure various physiological signals. Full article

(This article belongs to the Special Issue Flexible Electronics and Sensors)

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26 pages, 4134 KiB

Open AccessArticle

A Phonocardiographic-Based Fiber-Optic Sensor and Adaptive Filtering System for Noninvasive Continuous Fetal Heart Rate Monitoring

by Radek Martinek^1,*

, Jan Nedoma²

, Marcel Fajkus²

, Radana Kahankova¹

, Jaromir Konecny¹, Petr Janku³, Stanislav Kepak²

, Petr Bilik¹ and Homer Nazeran⁴

¹ Department of Cybernetics and Biomedical Engineering, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, 17 Listopadu 15, Ostrava 70833, Czech Republic

² Department of Telecommunications, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, 17 Listopadu 15, Ostrava 70833, Czech Republic

³ Department of Obstetrics and Gynecology, Masaryk University and University Hospital Brno, Jihlavska 20, 625 00 Brno, Czech Republic

⁴ Department of Electrical and Computer Engineering, University of Texas El Paso, 500 W University Ave, El Paso, TX 79968, USA

Sensors 2017, 17(4), 890; https://doi.org/10.3390/s17040890 - 18 Apr 2017

Cited by 91 | Viewed by 12540

Abstract

This paper focuses on the design, realization, and verification of a novel phonocardiographic- based fiber-optic sensor and adaptive signal processing system for noninvasive continuous fetal heart rate (fHR) monitoring. Our proposed system utilizes two Mach-Zehnder interferometeric sensors. Based on the analysis of real [...] Read more.

This paper focuses on the design, realization, and verification of a novel phonocardiographic- based fiber-optic sensor and adaptive signal processing system for noninvasive continuous fetal heart rate (fHR) monitoring. Our proposed system utilizes two Mach-Zehnder interferometeric sensors. Based on the analysis of real measurement data, we developed a simplified dynamic model for the generation and distribution of heart sounds throughout the human body. Building on this signal model, we then designed, implemented, and verified our adaptive signal processing system by implementing two stochastic gradient-based algorithms: the Least Mean Square Algorithm (LMS), and the Normalized Least Mean Square (NLMS) Algorithm. With this system we were able to extract the fHR information from high quality fetal phonocardiograms (fPCGs), filtered from abdominal maternal phonocardiograms (mPCGs) by performing fPCG signal peak detection. Common signal processing methods such as linear filtering, signal subtraction, and others could not be used for this purpose as fPCG and mPCG signals share overlapping frequency spectra. The performance of the adaptive system was evaluated by using both qualitative (gynecological studies) and quantitative measures such as: Signal-to-Noise Ratio—SNR, Root Mean Square Error—RMSE, Sensitivity—S+, and Positive Predictive Value—PPV. Full article

(This article belongs to the Section Biosensors)

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8 pages, 1198 KiB

Open AccessArticle

Fast Bragg Grating Inscription in PMMA Polymer Optical Fibres: Impact of Thermal Pre-Treatment of Preforms

by Carlos A. F. Marques^1,2,*, Andreas Pospori²

, Gökhan Demirci³, Onur Çetinkaya⁴

, Barbara Gawdzik³

, Paulo Antunes¹, Ole Bang⁴, Pawel Mergo⁵, Paulo André⁶ and David J. Webb²

¹ Instituto de Telecomunicações and Physics Department & I3N, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

² Aston Institute of Photonic Technologies, Aston University, Aston Triangle, B4 7ET Birmingham, UK

³ Department of Polymer Chemistry, Maria Curie-Sklodowska University, 20-031 Lublin, Poland

⁴ Laboratory of Optical Fibre Technology, Maria Curie-Sklodowska University, 20-031 Lublin, Poland

⁵ Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark

⁶ Instituto de Telecomunicações and Department of Electrical and Computer Engineering, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal

Sensors 2017, 17(4), 891; https://doi.org/10.3390/s17040891 - 18 Apr 2017

Cited by 71 | Viewed by 6230

Abstract

In this work, fibre Bragg gratings (FBGs) were inscribed in two different undoped poly- (methyl methacrylate) (PMMA) polymer optical fibres (POFs) using different types of UV lasers and their inscription times, temperature and strain sensitivities are investigated. The POF Bragg gratings (POFBGs) were [...] Read more.

In this work, fibre Bragg gratings (FBGs) were inscribed in two different undoped poly- (methyl methacrylate) (PMMA) polymer optical fibres (POFs) using different types of UV lasers and their inscription times, temperature and strain sensitivities are investigated. The POF Bragg gratings (POFBGs) were inscribed using two UV lasers: a continuous UV HeCd @325 nm laser and a pulsed UV KrF @248 nm laser. Two PMMA POFs are used in which the primary and secondary preforms (during the two-step drawing process) have a different thermal treatment. The PMMA POFs drawn in which the primary or secondary preform is not specifically pre-treated need longer inscription time than the fibres drawn where both preforms have been pre-annealed at 80 °C for 2 weeks. Using both UV lasers, for the latter fibre much less inscription time is needed compared to another homemade POF. The properties of a POF fabricated with both preforms thermally well annealed are different from those in which just one preform step process is thermally treated, with the first POFs being much less sensitive to thermal treatment. The influence of annealing on the strain and temperature sensitivities of the fibres prior to FBG inscription is also discussed, where it is observed that the fibre produced from a two-step drawing process with well-defined pre-annealing of both preforms did not produce any significant difference in sensitivity. The results indicate the impact of preform thermal pre-treatment before the PMMA POFs drawing, which can be an essential characteristic in the view of developing POF sensors technology. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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14 pages, 11769 KiB

Open AccessArticle

Microfluidic EBG Sensor Based on Phase-Shift Method Realized Using 3D Printing Technology

by Vasa Radonić^*

, Slobodan Birgermajer and Goran Kitić

BioSense Institute—Research Institute for Information Technologies in Biosystems, Dr Zorana Đinđića 1a, 21000 Novi Sad, Serbia

Sensors 2017, 17(4), 892; https://doi.org/10.3390/s17040892 - 18 Apr 2017

Cited by 23 | Viewed by 6638

Abstract

In this article, we propose a novel microfluidic microstrip electromagnetic band gap (EBG) sensor realized using cost-effective 3D printing technology. Microstrip sensor allows monitoring of the fluid properties flowing in the microchannel embedded between the microstrip line and ground plane. The sensor’s operating [...] Read more.

In this article, we propose a novel microfluidic microstrip electromagnetic band gap (EBG) sensor realized using cost-effective 3D printing technology. Microstrip sensor allows monitoring of the fluid properties flowing in the microchannel embedded between the microstrip line and ground plane. The sensor’s operating principle is based on the phase-shift method, which allows the characterization at a single operating frequency of 6 GHz. The defected electromagnetic band gap (EBG) structure is realized as a pattern in the microstrip ground plane to improve sensor sensitivity. The designed microfluidic channel is fabricated using a fused deposition modelling (FDM) 3D printing process without additional supporting layers, while the conductive layers are realized using sticky aluminium tape. The measurement results show that the change of permittivity of the fluid in the microfluidic channel from 1 to 80 results in the phase-shift difference of almost 90°. The potential application is demonstrated through the implementation of a proposed sensor for the detection of toluene concentration in toluene–methanol mixture where various concentrations of toluene were analysed. Full article

(This article belongs to the Special Issue 3D Printed Sensors)

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17 pages, 6113 KiB

Open AccessArticle

Study on Temperature and Synthetic Compensation of Piezo-Resistive Differential Pressure Sensors by Coupled Simulated Annealing and Simplex Optimized Kernel Extreme Learning Machine

by Ji Li¹, Guoqing Hu^1,2,*, Yonghong Zhou³, Chong Zou³, Wei Peng² and Jahangir Alam SM²

¹ Department of Mechanical and Electrical Engineering, School of Aerospace Engineering, Xiamen University, Xiamen 361005, China

² Department of Mechatronics Engineering, School of Mechanical & Automotive Engineering, South China University of Technology, Guangzhou 510640, China

³ Fujian Wide Plus Precision Instruments Co. Ltd., Fuzhou 350015, China

Sensors 2017, 17(4), 894; https://doi.org/10.3390/s17040894 - 19 Apr 2017

Cited by 16 | Viewed by 4908

Abstract

As a high performance-cost ratio solution for differential pressure measurement, piezo-resistive differential pressure sensors are widely used in engineering processes. However, their performance is severely affected by the environmental temperature and the static pressure applied to them. In order to modify the non-linear [...] Read more.

As a high performance-cost ratio solution for differential pressure measurement, piezo-resistive differential pressure sensors are widely used in engineering processes. However, their performance is severely affected by the environmental temperature and the static pressure applied to them. In order to modify the non-linear measuring characteristics of the piezo-resistive differential pressure sensor, compensation actions should synthetically consider these two aspects. Advantages such as nonlinear approximation capability, highly desirable generalization ability and computational efficiency make the kernel extreme learning machine (KELM) a practical approach for this critical task. Since the KELM model is intrinsically sensitive to the regularization parameter and the kernel parameter, a searching scheme combining the coupled simulated annealing (CSA) algorithm and the Nelder-Mead simplex algorithm is adopted to find an optimal KLEM parameter set. A calibration experiment at different working pressure levels was conducted within the temperature range to assess the proposed method. In comparison with other compensation models such as the back-propagation neural network (BP), radius basis neural network (RBF), particle swarm optimization optimized support vector machine (PSO-SVM), particle swarm optimization optimized least squares support vector machine (PSO-LSSVM) and extreme learning machine (ELM), the compensation results show that the presented compensation algorithm exhibits a more satisfactory performance with respect to temperature compensation and synthetic compensation problems. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 13080 KiB

Open AccessArticle

A Low Cost BLE Transceiver with RX Matching Network Reusing PA Load Inductor for WSNs Applications

by Zhen Liang^1,2, Bin Li¹, Mo Huang^1,*, Yanqi Zheng¹, Hui Ye^1,2, Ken Xu^1,2 and Fangming Deng³

¹ School of Electronics and Information Engineering, South China University of Technology, Guangzhou 510641, China

² Rising Micro Electronics Co., Ltd., Guangzhou 510006, China

³ School of Electrical and Automation Engineering, East China JiaoTong University, Nanchang 330013, China

Sensors 2017, 17(4), 895; https://doi.org/10.3390/s17040895 - 19 Apr 2017

Cited by 6 | Viewed by 6743

Abstract

In this work, a low cost Bluetooth Low Energy (BLE) transceiver for wireless sensor network (WSN) applications, with a receiver (RX) matching network reusing power amplifier (PA) load inductor, is presented. In order to decrease the die area, only two inductors were used [...] Read more.

In this work, a low cost Bluetooth Low Energy (BLE) transceiver for wireless sensor network (WSN) applications, with a receiver (RX) matching network reusing power amplifier (PA) load inductor, is presented. In order to decrease the die area, only two inductors were used in this work. Besides the one used in the voltage control oscillator (VCO), the PA load inductor was reused as the RX impedance matching component in the front-end. Proper controls have been applied to achieve high transmitter (TX) input impedance when the transceiver is in the receiving mode, and vice versa. This allows the TRX-switch/matching network integration without significant performance degradation. The RX adopted a low-IF structure and integrated a single-ended low noise amplifier (LNA), a current bleeding mixer, a 4th complex filter and a delta-sigma continuous time (CT) analog-to-digital converter (ADC). The TX employed a two-point PLL-based architecture with a non-linear PA. The RX achieved a sensitivity of −93 dBm and consumes 9.7 mW, while the TX achieved a 2.97% error vector magnitude (EVM) with 9.4 mW at 0 dBm output power. This design was fabricated in a 0.11 μm complementary metal oxide semiconductor (CMOS) technology and the front-end circuit only occupies 0.24 mm². The measurement results verify the effectiveness and applicability of the proposed BLE transceiver for WSN applications. Full article

(This article belongs to the Section Sensor Networks)

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13 pages, 24494 KiB

Open AccessArticle

The Effect of Particles on Electrolytically Polymerized Thin Natural MCF Rubber for Soft Sensors Installed in Artificial Skin

by Kunio Shimada^1,*

, Osamu Mochizuki² and Yoshihiro Kubota²

¹ Faculty of Symbiotic Systems Sciences, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan

² Department of Biomedical Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585, Japan

Sensors 2017, 17(4), 896; https://doi.org/10.3390/s17040896 - 19 Apr 2017

Cited by 11 | Viewed by 4324

Abstract

The aim of this study is to investigate the effect of particles as filler in soft rubber sensors installed in artificial skin. We examine sensors made of natural rubber (NR-latex) that include magnetic particles of Ni and Fe₃O₄ using magnetic [...] Read more.

The aim of this study is to investigate the effect of particles as filler in soft rubber sensors installed in artificial skin. We examine sensors made of natural rubber (NR-latex) that include magnetic particles of Ni and Fe₃O₄ using magnetic compound fluid (MCF). The 1-mm thickness of the electrolytically polymerized MCF rubber makes production of comparatively thin rubber sensors feasible. We first investigate the effect of magnetic particles Ni and Fe₃O₄ on the curing of MCF rubber. Next, in order to adjust the electric properties of the MCF rubber, we adopt Al₂O₃ dielectric particles. We investigate the effect of Al₂O₃ particles on changes in electric current, voltage and temperature of electrolytically polymerized MCF rubber liquid, and on the electric properties under the application of normal and shear forces. By adjusting the ratio of Ni, Fe₃O₄, Al₂O₃ and water in MCF rubber with Al₂O₃, it is possible to change the electric properties. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 8591 KiB

Open AccessArticle

Multisensory System for the Detection and Localization of Peripheral Subcutaneous Veins

by Roemi Fernández^*

and Manuel Armada

Centre for Automation and Robotics (CAR) CSIC-UPM, Carretera de Campo Real, Km. 0,200. La Poveda, Arganda del Rey, 28500 Madrid, Spain

Sensors 2017, 17(4), 897; https://doi.org/10.3390/s17040897 - 19 Apr 2017

Cited by 14 | Viewed by 6427

Abstract

This paper proposes a multisensory system for the detection and localization of peripheral subcutaneous veins, as a first step for achieving automatic robotic insertion of catheters in the near future. The multisensory system is based on the combination of a SWIR (Short-Wave Infrared) [...] Read more.

This paper proposes a multisensory system for the detection and localization of peripheral subcutaneous veins, as a first step for achieving automatic robotic insertion of catheters in the near future. The multisensory system is based on the combination of a SWIR (Short-Wave Infrared) camera, a TOF (Time-Of-Flight) camera and a NIR (Near Infrared) lighting source. The associated algorithm consists of two main parts: one devoted to the features extraction from the SWIR image, and another envisaged for the registration of the range data provided by the TOF camera, with the SWIR image and the results of the peripheral veins detection. In this way, the detected subcutaneous veins are mapped onto the 3D reconstructed surface, providing a full representation of the region of interest for the automatic catheter insertion. Several experimental tests were carried out in order to evaluate the capabilities of the presented approach. Preliminary results demonstrate the feasibility of the proposed design and highlight the potential benefits of the solution. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2017)

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21 pages, 686 KiB

Open AccessArticle

An Algorithm for Timely Transmission of Solicitation Messages in RPL for Energy-Efficient Node Mobility

by Jihong Park¹, Ki-Hyung Kim² and Kangseok Kim^2,*

¹ Department of Computer Engineering, Graduate School of Ajou University, Suwon 16499, Korea

² Department of Cyber Security, Ajou University, Suwon 16499, Korea

Sensors 2017, 17(4), 899; https://doi.org/10.3390/s17040899 - 19 Apr 2017

Cited by 20 | Viewed by 4599

Abstract

The IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) was proposed for various applications of IPv6 low power wireless networks. While RPL supports various routing metrics and is designed to be suitable for wireless sensor network environments, it does not consider [...] Read more.

The IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) was proposed for various applications of IPv6 low power wireless networks. While RPL supports various routing metrics and is designed to be suitable for wireless sensor network environments, it does not consider the mobility of nodes. Therefore, there is a need for a method that is energy efficient and that provides stable and reliable data transmission by considering the mobility of nodes in RPL networks. This paper proposes an algorithm to support node mobility in RPL in an energy-efficient manner and describes its operating principle based on different scenarios. The proposed algorithm supports the mobility of nodes by dynamically adjusting the transmission interval of the messages that request the route based on the speed and direction of the motion of mobile nodes, as well as the costs between neighboring nodes. The performance of the proposed algorithm and previous algorithms for supporting node mobility were examined experimentally. From the experiment, it was observed that the proposed algorithm requires fewer messages per unit time for selecting a new parent node following the movement of a mobile node. Since fewer messages are used to select a parent node, the energy consumption is also less than that of previous algorithms. Full article

(This article belongs to the Section Sensor Networks)

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32 pages, 4170 KiB

Open AccessArticle

Cross Layer Design for Optimizing Transmission Reliability, Energy Efficiency, and Lifetime in Body Sensor Networks

by Xi Chen, Yixuan Xu and Anfeng Liu^*

School of Information Science and Engineering, Central South University, Changsha 410083, China

Sensors 2017, 17(4), 900; https://doi.org/10.3390/s17040900 - 19 Apr 2017

Cited by 65 | Viewed by 7642

Abstract

High transmission reliability, energy efficiency, and long lifetime are pivotal issues for wireless body area networks (WBANs. However, these performance metrics are not independent of each other, making it hard to obtain overall improvements through optimizing one single aspect. Therefore, a Cross Layer [...] Read more.

High transmission reliability, energy efficiency, and long lifetime are pivotal issues for wireless body area networks (WBANs. However, these performance metrics are not independent of each other, making it hard to obtain overall improvements through optimizing one single aspect. Therefore, a Cross Layer Design Optimal (CLDO) scheme is proposed to simultaneously optimize transmission reliability, energy efficiency, and lifetime of WBANs from several layers. Firstly, due to the fact that the transmission power of nodes directly influences the reliability of links, the optimized transmission power of different nodes is deduced, which is able to maximize energy efficiency in theory under the premise that requirements on delay and jitter are fulfilled. Secondly, a relay decision algorithm is proposed to choose optimized relay nodes. Using this algorithm, nodes will choose relay nodes that ensure a balance of network energy consumption, provided that all nodes transmit with optimized transmission power and the same packet size. Thirdly, the energy consumption of nodes is still unbalanced even with optimized transmission power because of their different locations in the topology of the network. In addition, packet size also has an impact on final performance metrics. Therefore, a synthesized cross layer method for optimization is proposed. With this method, the transmission power of nodes with more residual energy will be enhanced while suitable packet size is determined for different links in the network, leading to further improvements in the WBAN system. Both our comprehensive theoretical analysis and experimental results indicate that the performance of our proposed scheme is better than reported in previous studies. Relative to the relay selection and power control game (RSPCG) scheme, the CLDO scheme can enhance transmission reliability by more than 44.6% and prolong the lifetime by as much as 33.2%. Full article

(This article belongs to the Special Issue Advances in Body Sensor Networks: Sensors, Systems, and Applications)

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15 pages, 5891 KiB

Open AccessArticle

Resonant Rectifier ICs for Piezoelectric Energy Harvesting Using Low-Voltage Drop Diode Equivalents

by Amad Ud Din, Seneke Chamith Chandrathna and Jong-Wook Lee^*

Department of Electronics Engineering, Information and Communication System-on-Chip (SoC) Research Center, Kyung Hee University, Yongin 17104, Korea

Sensors 2017, 17(4), 901; https://doi.org/10.3390/s17040901 - 19 Apr 2017

Cited by 6 | Viewed by 6539

Abstract

Herein, we present the design technique of a resonant rectifier for piezoelectric (PE) energy harvesting. We propose two diode equivalents to reduce the voltage drop in the rectifier operation, a minuscule-drop-diode equivalent (MDDE) and a low-drop-diode equivalent (LDDE). The diode equivalents are embedded [...] Read more.

Herein, we present the design technique of a resonant rectifier for piezoelectric (PE) energy harvesting. We propose two diode equivalents to reduce the voltage drop in the rectifier operation, a minuscule-drop-diode equivalent (MDDE) and a low-drop-diode equivalent (LDDE). The diode equivalents are embedded in resonant rectifier integrated circuits (ICs), which use symmetric bias-flip to reduce the power used for charging and discharging the internal capacitance of a PE transducer. The self-startup function is supported by synchronously generating control pulses for the bias-flip from the PE transducer. Two resonant rectifier ICs, using both MDDE and LDDE, are fabricated in a 0.18 μm CMOS process and their performances are characterized under external and self-power conditions. Under the external-power condition, the rectifier using LDDE delivers an output power P_OUT of 564 μW and a rectifier output voltage V_RECT of 3.36 V with a power transfer efficiency of 68.1%. Under self-power conditions, the rectifier using MDDE delivers a P_OUT of 288 μW and a V_RECT of 2.4 V with a corresponding efficiency of 78.4%. Using the proposed bias-flip technique, the power extraction capability of the proposed rectifier is 5.9 and 3.0 times higher than that of a conventional full-bridge rectifier. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 1766 KiB

Open AccessArticle

Connectivity Restoration in Wireless Sensor Networks via Space Network Coding

by Alfred Uwitonze¹, Jiaqing Huang^1,*, Yuanqing Ye² and Wenqing Cheng¹

¹ School of Electronic Information & Communications, Huazhong University of Science & Technology, 1037 Luoyu Road, Hongshan District, Wuhan 430074, China

² Department of Electrical & Computer Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA

Sensors 2017, 17(4), 902; https://doi.org/10.3390/s17040902 - 20 Apr 2017

Cited by 13 | Viewed by 4314

Abstract

The problem of finding the number and optimal positions of relay nodes for restoring the network connectivity in partitioned Wireless Sensor Networks (WSNs) is Non-deterministic Polynomial-time hard (NP-hard) and thus heuristic methods are preferred to solve it. This paper proposes a novel polynomial [...] Read more.

The problem of finding the number and optimal positions of relay nodes for restoring the network connectivity in partitioned Wireless Sensor Networks (WSNs) is Non-deterministic Polynomial-time hard (NP-hard) and thus heuristic methods are preferred to solve it. This paper proposes a novel polynomial time heuristic algorithm, namely, Relay Placement using Space Network Coding (RPSNC), to solve this problem, where Space Network Coding, also called Space Information Flow (SIF), is a new research paradigm that studies network coding in Euclidean space, in which extra relay nodes can be introduced to reduce the cost of communication. Unlike contemporary schemes that are often based on Minimum Spanning Tree (MST), Euclidean Steiner Minimal Tree (ESMT) or a combination of MST with ESMT, RPSNC is a new min-cost multicast space network coding approach that combines Delaunay triangulation and non-uniform partitioning techniques for generating a number of candidate relay nodes, and then linear programming is applied for choosing the optimal relay nodes and computing their connection links with terminals. Subsequently, an equilibrium method is used to refine the locations of the optimal relay nodes, by moving them to balanced positions. RPSNC can adapt to any density distribution of relay nodes and terminals, as well as any density distribution of terminals. The performance and complexity of RPSNC are analyzed and its performance is validated through simulation experiments. Full article

(This article belongs to the Section Sensor Networks)

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19 pages, 6808 KiB

Open AccessArticle

Robot-Beacon Distributed Range-Only SLAM for Resource-Constrained Operation

by Arturo Torres-González

, Jose Ramiro Martínez-de Dios^* and Anibal Ollero

Robotics Vision and Control Group, University of Sevilla, Escuela Superior de Ingenieros, c/Camino de los Descubrimientos s/n, 41092 Seville, Spain

Sensors 2017, 17(4), 903; https://doi.org/10.3390/s17040903 - 20 Apr 2017

Cited by 12 | Viewed by 6168

Abstract

This work deals with robot-sensor network cooperation where sensor nodes (beacons) are used as landmarks for Range-Only (RO) Simultaneous Localization and Mapping (SLAM). Most existing RO-SLAM techniques consider beacons as passive devices disregarding the sensing, computational and communication capabilities with which they are [...] Read more.

This work deals with robot-sensor network cooperation where sensor nodes (beacons) are used as landmarks for Range-Only (RO) Simultaneous Localization and Mapping (SLAM). Most existing RO-SLAM techniques consider beacons as passive devices disregarding the sensing, computational and communication capabilities with which they are actually endowed. SLAM is a resource-demanding task. Besides the technological constraints of the robot and beacons, many applications impose further resource consumption limitations. This paper presents a scalable distributed RO-SLAM scheme for resource-constrained operation. It is capable of exploiting robot-beacon cooperation in order to improve SLAM accuracy while meeting a given resource consumption bound expressed as the maximum number of measurements that are integrated in SLAM per iteration. The proposed scheme combines a Sparse Extended Information Filter (SEIF) SLAM method, in which each beacon gathers and integrates robot-beacon and inter-beacon measurements, and a distributed information-driven measurement allocation tool that dynamically selects the measurements that are integrated in SLAM, balancing uncertainty improvement and resource consumption. The scheme adopts a robot-beacon distributed approach in which each beacon participates in the selection, gathering and integration in SLAM of robot-beacon and inter-beacon measurements, resulting in significant estimation accuracies, resource-consumption efficiency and scalability. It has been integrated in an octorotor Unmanned Aerial System (UAS) and evaluated in 3D SLAM outdoor experiments. The experimental results obtained show its performance and robustness and evidence its advantages over existing methods. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2017)

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23 pages, 3200 KiB

Open AccessArticle

Chemical Source Localization Fusing Concentration Information in the Presence of Chemical Background Noise

by Víctor Pomareda^1,2, Rudys Magrans¹, Juan M. Jiménez-Soto¹, Dani Martínez³, Marcel Tresánchez³

, Javier Burgués^1,2

, Jordi Palacín³

and Santiago Marco^1,2,*,†

¹ Signal and Information Processing for Sensing Systems, Institute for Bioengineering of Catalonia, Baldiri Reixac 4-8, Barcelona 08028, Spain

² Department of Engineering: Electronics, Universitat de Barcelona, Martí i Franqués 1, Barcelona 08028, Spain

³ Department of Computer Science and Industrial Engineering, Universitat de Lleida, Jaume II 69, Lleida 25001, Spain

^† This paper is an extended version of our paper: Pomareda, V.; Marco, S. Chemical Plume Source Localization with Multiple Mobile Sensors using Bayesian Inference under Background Signals. In Proceedings of the International Symposium on Olfaction and Electronic Nose, New York, NY, USA, 2–5 May 2011.

Sensors 2017, 17(4), 904; https://doi.org/10.3390/s17040904 - 20 Apr 2017

Cited by 9 | Viewed by 8704

Abstract

We present the estimation of a likelihood map for the location of the source of a chemical plume dispersed under atmospheric turbulence under uniform wind conditions. The main contribution of this work is to extend previous proposals based on Bayesian inference with binary [...] Read more.

We present the estimation of a likelihood map for the location of the source of a chemical plume dispersed under atmospheric turbulence under uniform wind conditions. The main contribution of this work is to extend previous proposals based on Bayesian inference with binary detections to the use of concentration information while at the same time being robust against the presence of background chemical noise. For that, the algorithm builds a background model with robust statistics measurements to assess the posterior probability that a given chemical concentration reading comes from the background or from a source emitting at a distance with a specific release rate. In addition, our algorithm allows multiple mobile gas sensors to be used. Ten realistic simulations and ten real data experiments are used for evaluation purposes. For the simulations, we have supposed that sensors are mounted on cars which do not have among its main tasks navigating toward the source. To collect the real dataset, a special arena with induced wind is built, and an autonomous vehicle equipped with several sensors, including a photo ionization detector (PID) for sensing chemical concentration, is used. Simulation results show that our algorithm, provides a better estimation of the source location even for a low background level that benefits the performance of binary version. The improvement is clear for the synthetic data while for real data the estimation is only slightly better, probably because our exploration arena is not able to provide uniform wind conditions. Finally, an estimation of the computational cost of the algorithmic proposal is presented. Full article

(This article belongs to the Section Chemical Sensors)

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12 pages, 19363 KiB

Open AccessArticle

Deep Count: Fruit Counting Based on Deep Simulated Learning

by Maryam Rahnemoonfar^* and Clay Sheppard

Department of Computer Science, Texas A&M University-Corpus Christi, Corpus Christi, TX 78412, USA

Sensors 2017, 17(4), 905; https://doi.org/10.3390/s17040905 - 20 Apr 2017

Cited by 457 | Viewed by 24090

Abstract

Recent years have witnessed significant advancement in computer vision research based on deep learning. Success of these tasks largely depends on the availability of a large amount of training samples. Labeling the training samples is an expensive process. In this paper, we present [...] Read more.

Recent years have witnessed significant advancement in computer vision research based on deep learning. Success of these tasks largely depends on the availability of a large amount of training samples. Labeling the training samples is an expensive process. In this paper, we present a simulated deep convolutional neural network for yield estimation. Knowing the exact number of fruits, flowers, and trees helps farmers to make better decisions on cultivation practices, plant disease prevention, and the size of harvest labor force. The current practice of yield estimation based on the manual counting of fruits or flowers by workers is a very time consuming and expensive process and it is not practical for big fields. Automatic yield estimation based on robotic agriculture provides a viable solution in this regard. Our network is trained entirely on synthetic data and tested on real data. To capture features on multiple scales, we used a modified version of the Inception-ResNet architecture. Our algorithm counts efficiently even if fruits are under shadow, occluded by foliage, branches, or if there is some degree of overlap amongst fruits. Experimental results show a 91% average test accuracy on real images and 93% on synthetic images. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 282 KiB

Open AccessArticle

Characterization of N-Acyl Homoserine Lactones in Vibrio tasmaniensis LGP32 by a Biosensor-Based UHPLC-HRMS/MS Method

by Léa Girard¹, Élodie Blanchet¹, Laurent Intertaglia², Julia Baudart¹, Didier Stien¹, Marcelino Suzuki¹

, Philippe Lebaron¹ and Raphaël Lami^1,*

¹ Sorbonne Universités, UPMC Univ Paris 6, CNRS, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, F-66650 Banyuls/Mer, France

² Sorbonne Universités, UPMC Univ Paris 06, CNRS, Observatoire Océanologique de Banyuls (OOB), F-66650 Banyuls/Mer, France

Sensors 2017, 17(4), 906; https://doi.org/10.3390/s17040906 - 20 Apr 2017

Cited by 21 | Viewed by 5617

Abstract

Since the discovery of quorum sensing (QS) in the 1970s, many studies have demonstrated that Vibrio species coordinate activities such as biofilm formation, virulence, pathogenesis, and bioluminescence, through a large group of molecules called N-acyl homoserine lactones (AHLs). However, despite the extensive [...] Read more.

Since the discovery of quorum sensing (QS) in the 1970s, many studies have demonstrated that Vibrio species coordinate activities such as biofilm formation, virulence, pathogenesis, and bioluminescence, through a large group of molecules called N-acyl homoserine lactones (AHLs). However, despite the extensive knowledge on the involved molecules and the biological processes controlled by QS in a few selected Vibrio strains, less is known about the overall diversity of AHLs produced by a broader range of environmental strains. To investigate the prevalence of QS capability of Vibrio environmental strains we analyzed 87 Vibrio spp. strains from the Banyuls Bacterial Culture Collection (WDCM911) for their ability to produce AHLs. This screening was based on three biosensors, which cover a large spectrum of AHLs, and revealed that only 9% of the screened isolates produced AHLs in the defined experimental conditions. Among these AHL-producing strains, Vibrio tasmaniensis LGP32 is a well-known pathogen of bivalves. We further analyzed the diversity of AHLs produced by this strain using a sensitive bioguided UHPLC-HRMS/MS approach (Ultra-High-Performance Liquid Chromatography followed by High-Resolution tandem Mass Spectrometry) and we identified C10-HSL, OH-C12-HSL, oxo-C12-HSL and C14:1-HSL as QS molecules. This is the first report that documents the production of AHL by Vibrio tasmaniensis LGP32. Full article

(This article belongs to the Special Issue Sensors for Toxic and Pathogen Detection)

21 pages, 2594 KiB

Open AccessArticle

An Efficient Distributed Compressed Sensing Algorithm for Decentralized Sensor Network

by Jing Liu^*, Kaiyu Huang

and Guoxian Zhang

School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(4), 907; https://doi.org/10.3390/s17040907 - 20 Apr 2017

Cited by 9 | Viewed by 4528

Abstract

We consider the joint sparsity Model 1 (JSM-1) in a decentralized scenario, where a number of sensors are connected through a network and there is no fusion center. A novel algorithm, named distributed compact sensing matrix pursuit (DCSMP), is proposed to exploit the [...] Read more.

We consider the joint sparsity Model 1 (JSM-1) in a decentralized scenario, where a number of sensors are connected through a network and there is no fusion center. A novel algorithm, named distributed compact sensing matrix pursuit (DCSMP), is proposed to exploit the computational and communication capabilities of the sensor nodes. In contrast to the conventional distributed compressed sensing algorithms adopting a random sensing matrix, the proposed algorithm focuses on the deterministic sensing matrices built directly on the real acquisition systems. The proposed DCSMP algorithm can be divided into two independent parts, the common and innovation support set estimation processes. The goal of the common support set estimation process is to obtain an estimated common support set by fusing the candidate support set information from an individual node and its neighboring nodes. In the following innovation support set estimation process, the measurement vector is projected into a subspace that is perpendicular to the subspace spanned by the columns indexed by the estimated common support set, to remove the impact of the estimated common support set. We can then search the innovation support set using an orthogonal matching pursuit (OMP) algorithm based on the projected measurement vector and projected sensing matrix. In the proposed DCSMP algorithm, the process of estimating the common component/support set is decoupled with that of estimating the innovation component/support set. Thus, the inaccurately estimated common support set will have no impact on estimating the innovation support set. It is proven that under the condition the estimated common support set contains the true common support set, the proposed algorithm can find the true innovation set correctly. Moreover, since the innovation support set estimation process is independent of the common support set estimation process, there is no requirement for the cardinality of both sets; thus, the proposed DCSMP algorithm is capable of tackling the unknown sparsity problem successfully. Full article

(This article belongs to the Section Sensor Networks)

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11 pages, 3106 KiB

Open AccessArticle

Enhancing the Responsivity of Uncooled Infrared Detectors Using Plasmonics for High-Performance Infrared Spectroscopy

by Amr Shebl Ahmed¹, Hye Jin Kim², Jinsik Kim³, Kyo Seon Hwang^4,* and Seonghwan Kim^1,*

¹ Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada

² Center for BioMicrosystems, Korea Institute of Science and Technology, Seoul 02792, Korea

³ Department of Medical Biotechnology, Dongguk University, Seoul 10326, Korea

⁴ Department of Clinical Pharmacology and Therapeutics, Kyung Hee University, Seoul 02447, Korea

Sensors 2017, 17(4), 908; https://doi.org/10.3390/s17040908 - 20 Apr 2017

Cited by 14 | Viewed by 7655

Abstract

A lead zirconate titanate (PZT;Pb(Zr_0.52Ti_0.48)O₃) layer embedded infrared (IR) detector decorated with wavelength-selective plasmonic crystals has been investigated for high-performance non-dispersive infrared (NDIR) spectroscopy. A plasmonic IR detector with an enhanced IR absorption band has been designed [...] Read more.

A lead zirconate titanate (PZT;Pb(Zr_0.52Ti_0.48)O₃) layer embedded infrared (IR) detector decorated with wavelength-selective plasmonic crystals has been investigated for high-performance non-dispersive infrared (NDIR) spectroscopy. A plasmonic IR detector with an enhanced IR absorption band has been designed based on numerical simulations, fabricated by conventional microfabrication techniques, and characterized with a broadly tunable quantum cascade laser. The enhanced responsivity of the plasmonic IR detector at specific wavelength band has improved the performance of NDIR spectroscopy and pushed the limit of detection (LOD) by an order of magnitude. In this paper, a 13-fold enhancement in the LOD of a methane gas sensing using NDIR spectroscopy is demonstrated with the plasmonic IR detector. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Canada 2017)

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24 pages, 696 KiB

Open AccessArticle

Homomorphic Filtering for Improving Time Synchronization in Wireless Networks

by José María Castillo-Secilla^1,*, José Manuel Palomares²

, Fernando León³

and Joaquín Olivares²

¹ Department of Computer Technology, University of Alicante, Carretera San Vicente del Raspeig, S/N, 03690 Alicante, Spain

² Department of Computer Architecture, Electronics and Electronic Technology, Universidad de Córdoba, Campus de Rabanales, 14001 Córdoba, Spain

³ PRINIA Research Group, Universidad de Córdoba, Campus de Rabanales, 14001 Córdoba, Spain

Sensors 2017, 17(4), 909; https://doi.org/10.3390/s17040909 - 20 Apr 2017

Cited by 5 | Viewed by 4092

Abstract

Wireless sensor networks are used to sample the environment in a distributed way. Therefore, it is mandatory for all of the measurements to be tightly synchronized in order to guarantee that every sensor is sampling the environment at the exact same instant of [...] Read more.

Wireless sensor networks are used to sample the environment in a distributed way. Therefore, it is mandatory for all of the measurements to be tightly synchronized in order to guarantee that every sensor is sampling the environment at the exact same instant of time. The synchronization drift gets bigger in environments suffering from temperature variations. Thus, this work is focused on improving time synchronization under deployments with temperature variations. The working hypothesis demonstrated in this work is that the clock skew of two nodes (the ratio of the real frequencies of the oscillators) is composed of a multiplicative combination of two main components: the clock skew due to the variations between the cut of the crystal of each oscillator and the clock skew due to the different temperatures affecting the nodes. By applying a nonlinear filtering, the homomorphic filtering, both components are separated in an effective way. A correction factor based on temperature, which can be applied to any synchronization protocol, is proposed. For testing it, an improvement of the FTSP synchronization protocol has been developed and physically tested under temperature variation scenarios using TelosB motes flashed with the IEEE 802.15.4 implementation supplied by TinyOS. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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19 pages, 4835 KiB

Open AccessArticle

Investigating Surface and Near-Surface Bushfire Fuel Attributes: A Comparison between Visual Assessments and Image-Based Point Clouds

by Christine Spits^1,*, Luke Wallace^1,2

and Karin Reinke^1,2

¹ School of Science, RMIT University, Melbourne 3001, Australia

² Bushfire and Natural Hazards Cooperative Research Centre, East Melbourne 3002, Australia

Sensors 2017, 17(4), 910; https://doi.org/10.3390/s17040910 - 20 Apr 2017

Cited by 15 | Viewed by 5935

Abstract

Visual assessment, following guides such as the Overall Fuel Hazard Assessment Guide (OFHAG), is a common approach for assessing the structure and hazard of varying bushfire fuel layers. Visual assessments can be vulnerable to imprecision due to subjectivity between assessors, while emerging techniques [...] Read more.

Visual assessment, following guides such as the Overall Fuel Hazard Assessment Guide (OFHAG), is a common approach for assessing the structure and hazard of varying bushfire fuel layers. Visual assessments can be vulnerable to imprecision due to subjectivity between assessors, while emerging techniques such as image-based point clouds can offer land managers potentially more repeatable descriptions of fuel structure. This study compared the variability of estimates of surface and near-surface fuel attributes generated by eight assessment teams using the OFHAG and Fuels3D, a smartphone method utilising image-based point clouds, within three assessment plots in an Australian lowland forest. Surface fuel hazard scores derived from underpinning attributes were also assessed. Overall, this study found considerable variability between teams on most visually assessed variables, resulting in inconsistent hazard scores. Variability was observed within point cloud estimates but was, however, on average two to eight times less than that seen in visual estimates, indicating greater consistency and repeatability of this method. It is proposed that while variability within the Fuels3D method may be overcome through improved methods and equipment, inconsistencies in the OFHAG are likely due to the inherent subjectivity between assessors, which may be more difficult to overcome. This study demonstrates the capability of the Fuels3D method to efficiently and consistently collect data on fuel hazard and structure, and, as such, this method shows potential for use in fire management practices where accurate and reliable data is essential. Full article

(This article belongs to the Special Issue Advances in Applied Remote Sensing and Decision Making: Transforming Hazard Assessment and Environmental Management)

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15 pages, 8377 KiB

Open AccessArticle

Rapid Texture Optimization of Three-Dimensional Urban Model Based on Oblique Images

by Weilong Zhang¹, Ming Li^1,2,*

, Bingxuan Guo^1,*, Deren Li^1,2 and Ge Guo¹

¹ State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China

² Collaborative Innovation Center for Geospatial Technology, Wuhan University, Wuhan 430079, China

Sensors 2017, 17(4), 911; https://doi.org/10.3390/s17040911 - 20 Apr 2017

Cited by 12 | Viewed by 5281

Abstract

Seamless texture mapping is one of the key technologies for photorealistic 3D texture reconstruction. In this paper, a method of rapid texture optimization of 3D urban reconstruction based on oblique images is proposed aiming at the existence of texture fragments, seams, and inconsistency [...] Read more.

Seamless texture mapping is one of the key technologies for photorealistic 3D texture reconstruction. In this paper, a method of rapid texture optimization of 3D urban reconstruction based on oblique images is proposed aiming at the existence of texture fragments, seams, and inconsistency of color in urban 3D texture mapping based on low-altitude oblique images. First, we explore implementing radiation correction on the experimental images with a radiation procession algorithm. Then, an efficient occlusion detection algorithm based on OpenGL is proposed according to the mapping relation between the terrain triangular mesh surface and the images to implement the occlusion detection of the visible texture on the triangular facets as well as create a list of visible images. Finally, a texture clustering algorithm is put forward based on Markov Random Field utilizing the inherent attributes of the images and solve the energy function minimization by Graph-Cuts. The experimental results display that the method is capable of decreasing the existence of texture fragments, seams, and inconsistency of color in the 3D texture model reconstruction. Full article

(This article belongs to the Special Issue Urban Remote Sensing: Monitoring, Synthesis and Modeling in the Urban Environment)

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14 pages, 7690 KiB

Open AccessArticle

A Multi-Platform Optical Sensor for In Vivo and In Vitro Algae Classification

by Chee-Loon Ng^1,*, Qing-Qing Chen¹, Jia-Jing Chua¹ and Harold F. Hemond²

¹ Singapore-MIT Alliance for Research and Technology (SMART) Centre, 1 CREATE Way, CREATE Tower, #10-01, Singapore 138602, Singapore

² Massachusetts Institute of Technology, Parsons Laboratory, Room 48-425, 15 Vassar Street, Cambridge, MA 02139, USA

Sensors 2017, 17(4), 912; https://doi.org/10.3390/s17040912 - 20 Apr 2017

Cited by 7 | Viewed by 7577

Abstract

Differentiation among major algal groups is important for the ecological and biogeochemical characterization of water bodies, and for practical management of water resources. It helps to discern the taxonomic groups that are beneficial to aquatic life from the organisms causing harmful algal blooms. [...] Read more.

Differentiation among major algal groups is important for the ecological and biogeochemical characterization of water bodies, and for practical management of water resources. It helps to discern the taxonomic groups that are beneficial to aquatic life from the organisms causing harmful algal blooms. An LED-induced fluorescence (LEDIF) instrument capable of fluorescence, absorbance, and scattering measurements; is used for in vivo and in vitro identification and quantification of four algal groups found in freshwater and marine environments. Aqueous solutions of individual and mixed dissolved biological pigments relevant to different algal groups were measured to demonstrate the LEDIF’s capabilities in measuring extracted pigments. Different genera of algae were cultivated and the cell counts of the samples were quantified with a hemacytometer and/or cellometer. Dry weight of different algae cells was also measured to determine the cell counts-to-dry weight correlations. Finally, in vivo measurements of different genus of algae at different cell concentrations and mixed algal group in the presence of humic acid were performed with the LEDIF. A field sample from a local reservoir was measured with the LEDIF and the results were verified using hemacytometer, cellometer, and microscope. The results demonstrated the LEDIF’s capabilities in classifying and quantifying different groups of live algae. Full article

(This article belongs to the Special Issue Specialty Optical Fibers for Chemical and Biochemical Sensing: From Evanescent Waves to Plasmonic Interaction)

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14 pages, 3462 KiB

Open AccessArticle

Synthesis, Characterization and Enhanced Sensing Properties of a NiO/ZnO p–n Junctions Sensor for the SF₆ Decomposition Byproducts SO₂, SO₂F₂, and SOF₂

by Hongcheng Liu¹

, Qu Zhou^1,2,*

, Qingyan Zhang¹, Changxiang Hong¹, Lingna Xu^1,2, Lingfeng Jin²

and Weigen Chen²

¹ College of Engineering and Technology, Southwest University, Chongqing 400715, China

² State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400030, China

Sensors 2017, 17(4), 913; https://doi.org/10.3390/s17040913 - 21 Apr 2017

Cited by 88 | Viewed by 7778

Abstract

The detection of partial discharge and analysis of the composition and content of sulfur hexafluoride SF₆ gas components are important to evaluate the operating state and insulation level of gas-insulated switchgear (GIS) equipment. This paper reported a novel sensing material made of [...] Read more.

The detection of partial discharge and analysis of the composition and content of sulfur hexafluoride SF₆ gas components are important to evaluate the operating state and insulation level of gas-insulated switchgear (GIS) equipment. This paper reported a novel sensing material made of pure ZnO and NiO-decorated ZnO nanoflowers which were synthesized by a facile and environment friendly hydrothermal process for the detection of SF₆ decomposition byproducts. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structural and morphological properties of the prepared gas-sensitive materials. Planar-type chemical gas sensors were fabricated and their gas sensing performances toward the SF₆ decomposition byproducts SO₂, SO₂F₂, and SOF₂ were systemically investigated. Interestingly, the sensing behaviors of the fabricated ZnO nanoflowers-based sensor to SO₂, SO₂F₂, and SOF₂ gases can be obviously enhanced in terms of lower optimal operating temperature, higher gas response and shorter response-recovery time by introducing NiO. Finally, a possible gas sensing mechanism for the formation of the p–n junctions between NiO and ZnO is proposed to explain the enhanced gas response. All results demonstrate a promising approach to fabricate high-performance gas sensors to detect SF₆ decomposition byproducts. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 1778 KiB

Open AccessArticle

Influence of Wind Speed on RGB-D Images in Tree Plantations

by Dionisio Andújar^1,*, José Dorado²

, José María Bengochea-Guevara¹, Jesús Conesa-Muñoz¹

, César Fernández-Quintanilla² and Ángela Ribeiro¹

¹ Centre for Automation and Robotics, Spanish National Research Council, CSIC-UPM, Argandadel Rey, 28500 Madrid, Spain

² Institute of Agricultural Sciences, Spanish National Research Council, CSIC, 28006 Madrid, Spain

Sensors 2017, 17(4), 914; https://doi.org/10.3390/s17040914 - 21 Apr 2017

Cited by 18 | Viewed by 6002

Abstract

Weather conditions can affect sensors’ readings when sampling outdoors. Although sensors are usually set up covering a wide range of conditions, their operational range must be established. In recent years, depth cameras have been shown as a promising tool for plant phenotyping and [...] Read more.

Weather conditions can affect sensors’ readings when sampling outdoors. Although sensors are usually set up covering a wide range of conditions, their operational range must be established. In recent years, depth cameras have been shown as a promising tool for plant phenotyping and other related uses. However, the use of these devices is still challenged by prevailing field conditions. Although the influence of lighting conditions on the performance of these cameras has already been established, the effect of wind is still unknown. This study establishes the associated errors when modeling some tree characteristics at different wind speeds. A system using a Kinect v2 sensor and a custom software was tested from null wind speed up to 10 m·s⁻¹. Two tree species with contrasting architecture, poplars and plums, were used as model plants. The results showed different responses depending on tree species and wind speed. Estimations of Leaf Area (LA) and tree volume were generally more consistent at high wind speeds in plum trees. Poplars were particularly affected by wind speeds higher than 5 m·s⁻¹. On the contrary, height measurements were more consistent for poplars than for plum trees. These results show that the use of depth cameras for tree characterization must take into consideration wind conditions in the field. In general, 5 m·s⁻¹ (18 km·h⁻¹) could be established as a conservative limit for good estimations. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2017)

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23 pages, 8256 KiB

Open AccessArticle

Celestial Object Imaging Model and Parameter Optimization for an Optical Navigation Sensor Based on the Well Capacity Adjusting Scheme

by Hao Wang, Jie Jiang^* and Guangjun Zhang

Key Laboratory of Precision Opto-mechatronics Technology, Ministry of Education, School of Instrumentation Science and Opto-electronics Engineering, Beihang University, No. 37 Xueyuan Road, Haidian District, Beijing 100191, China

Sensors 2017, 17(4), 915; https://doi.org/10.3390/s17040915 - 21 Apr 2017

Cited by 6 | Viewed by 5175

Abstract

The simultaneous extraction of optical navigation measurements from a target celestial body and star images is essential for autonomous optical navigation. Generally, a single optical navigation sensor cannot simultaneously image the target celestial body and stars well-exposed because their irradiance difference is generally [...] Read more.

The simultaneous extraction of optical navigation measurements from a target celestial body and star images is essential for autonomous optical navigation. Generally, a single optical navigation sensor cannot simultaneously image the target celestial body and stars well-exposed because their irradiance difference is generally large. Multi-sensor integration or complex image processing algorithms are commonly utilized to solve the said problem. This study analyzes and demonstrates the feasibility of simultaneously imaging the target celestial body and stars well-exposed within a single exposure through a single field of view (FOV) optical navigation sensor using the well capacity adjusting (WCA) scheme. First, the irradiance characteristics of the celestial body are analyzed. Then, the celestial body edge model and star spot imaging model are established when the WCA scheme is applied. Furthermore, the effect of exposure parameters on the accuracy of star centroiding and edge extraction is analyzed using the proposed model. Optimal exposure parameters are also derived by conducting Monte Carlo simulation to obtain the best performance of the navigation sensor. Finally, laboratorial and night sky experiments are performed to validate the correctness of the proposed model and optimal exposure parameters. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 5590 KiB

Open AccessArticle

Suitability of Strain Gage Sensors for Integration into Smart Sport Equipment: A Golf Club Example

by Anton Umek^1,2

, Yuan Zhang^1,*

, Sašo Tomažič² and Anton Kos²

¹ Shandong Provincial Key Laboratory of Network Based Intelligent Computing, University of Jinan, Jinan 250022, China

² Faculty of Electrical Engineering, University of Ljubljana, 1000 Ljubljana, Slovenia

Sensors 2017, 17(4), 916; https://doi.org/10.3390/s17040916 - 21 Apr 2017

Cited by 30 | Viewed by 9819

Abstract

Wearable devices and smart sport equipment are being increasingly used in amateur and professional sports. Smart sport equipment employs various sensors for detecting its state and actions. The correct choice of the most appropriate sensor(s) is of paramount importance for efficient and successful [...] Read more.

Wearable devices and smart sport equipment are being increasingly used in amateur and professional sports. Smart sport equipment employs various sensors for detecting its state and actions. The correct choice of the most appropriate sensor(s) is of paramount importance for efficient and successful operation of sport equipment. When integrated into the sport equipment, ideal sensors are unobstructive, and do not change the functionality of the equipment. The article focuses on experiments for identification and selection of sensors that are suitable for the integration into a golf club with the final goal of their use in real time biofeedback applications. We tested two orthogonally affixed strain gage (SG) sensors, a 3-axis accelerometer, and a 3-axis gyroscope. The strain gage sensors are calibrated and validated in the laboratory environment by a highly accurate Qualisys Track Manager (QTM) optical tracking system. Field test results show that different types of golf swing and improper movement in early phases of golf swing can be detected with strain gage sensors attached to the shaft of the golf club. Thus they are suitable for biofeedback applications to help golfers to learn repetitive golf swings. It is suggested that the use of strain gage sensors can improve the golf swing technical error detection accuracy and that strain gage sensors alone are enough for basic golf swing analysis. Our final goal is to be able to acquire and analyze as many parameters of a smart golf club in real time during the entire duration of the swing. This would give us the ability to design mobile and cloud biofeedback applications with terminal or concurrent feedback that will enable us to speed-up motor skill learning in golf. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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18 pages, 9406 KiB

Open AccessArticle

Accurate Ambient Noise Assessment Using Smartphones

by Willian Zamora^1,2,*

, Carlos T. Calafate^1,†

, Juan-Carlos Cano^1,†

and Pietro Manzoni^1,†

¹ Department of Computing Engineering, Universitat Politècnica de València, 46022 València, Spain

² School of Computer Science, Universidad Laica Eloy Alfaro de Manabí, 130802 Manta, Ecuador

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 917; https://doi.org/10.3390/s17040917 - 21 Apr 2017

Cited by 46 | Viewed by 7754

Abstract

Nowadays, smartphones have become ubiquitous and one of the main communication resources for human beings. Their widespread adoption was due to the huge technological progress and to the development of multiple useful applications. Their characteristics have also experienced a substantial improvement as they [...] Read more.

Nowadays, smartphones have become ubiquitous and one of the main communication resources for human beings. Their widespread adoption was due to the huge technological progress and to the development of multiple useful applications. Their characteristics have also experienced a substantial improvement as they now integrate multiple sensors able to convert the smartphone into a flexible and multi-purpose sensing unit. The combined use of multiple smartphones endowed with several types of sensors gives the possibility to monitor a certain area with fine spatial and temporal granularity, a procedure typically known as crowdsensing. In this paper, we propose using smartphones as environmental noise-sensing units. For this purpose, we focus our study on the sound capture and processing procedure, analyzing the impact of different noise calculation algorithms, as well as in determining their accuracy when compared to a professional noise measurement unit. We analyze different candidate algorithms using different types of smartphones, and we study the most adequate time period and sampling strategy to optimize the data-gathering process. In addition, we perform an experimental study comparing our approach with the results obtained using a professional device. Experimental results show that, if the smartphone application is well tuned, it is possible to measure noise levels with a accuracy degree comparable to professional devices for the entire dynamic range typically supported by microphones embedded in smartphones, i.e., 35–95 dB. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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17 pages, 1598 KiB

Open AccessArticle

Autonomous Multi-Robot Search for a Hazardous Source in a Turbulent Environment

by Branko Ristic^1,*

, Daniel Angley¹

, Bill Moran¹ and Jennifer L. Palmer²

¹ School of Engineering, RMIT University, Melbourne, VIC 3000, Australia

² Aerospace Division, Defence Science and Technology, Fishermans Bend, VIC 3207, Australia

Sensors 2017, 17(4), 918; https://doi.org/10.3390/s17040918 - 21 Apr 2017

Cited by 37 | Viewed by 5223

Abstract

Finding the source of an accidental or deliberate release of a toxic substance into the atmosphere is of great importance for national security. The paper presents a search algorithm for turbulent environments which falls into the class of cognitive (infotaxi) algorithms. [...] Read more.

Finding the source of an accidental or deliberate release of a toxic substance into the atmosphere is of great importance for national security. The paper presents a search algorithm for turbulent environments which falls into the class of cognitive (infotaxi) algorithms. Bayesian estimation of the source parameter vector is carried out using the Rao–Blackwell dimension-reduction method, while the robots are controlled autonomously to move in a scalable formation. Estimation and control are carried out in a centralised replicated fusion architecture assuming all-to-all communication. The paper presents a comprehensive numerical analysis of the proposed algorithm, including the search-time and displacement statistics. Full article

(This article belongs to the Special Issue Sensor Intelligence Assisted by Data Analytics and Cognitive Computing)

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8 pages, 4160 KiB

Open AccessArticle

Image-Guided Laparoscopic Surgical Tool (IGLaST) Based on the Optical Frequency Domain Imaging (OFDI) to Prevent Bleeding

by Byung Jun Park^1,†, Seung Rag Lee^1,†, Hyun Jin Bang¹, Byung Yeon Kim¹, Jeong Hun Park¹, Dong Guk Kim¹, Sung Soo Park^2,* and Young Jae Won^1,*

¹ Medical Device Development Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk 361-951, Korea

² Department of Surgery, Korea University College of Medicine, Seoul 02841, Korea

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 919; https://doi.org/10.3390/s17040919 - 21 Apr 2017

Cited by 6 | Viewed by 6451

Abstract

We present an image-guided laparoscopic surgical tool (IGLaST) to prevent bleeding. By applying optical frequency domain imaging (OFDI) to a specially designed laparoscopic surgical tool, the inside of fatty tissue can be observed before a resection, and the presence and size of blood [...] Read more.

We present an image-guided laparoscopic surgical tool (IGLaST) to prevent bleeding. By applying optical frequency domain imaging (OFDI) to a specially designed laparoscopic surgical tool, the inside of fatty tissue can be observed before a resection, and the presence and size of blood vessels can be recognized. The optical sensing module on the IGLaST head has a diameter of less than 390 µm and is moved back and forth by a linear servo actuator in the IGLaST body. We proved the feasibility of IGLaST by in vivo imaging inside the fatty tissue of a porcine model. A blood vessel with a diameter of about 2.2 mm was clearly observed. Our proposed scheme can contribute to safe surgery without bleeding by monitoring vessels inside the tissue and can be further expanded to detect invisible nerves of the laparoscopic thyroid during prostate gland surgery. Full article

(This article belongs to the Special Issue Optical Methods in Sensing and Imaging for Medical and Biological Applications)

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18 pages, 1178 KiB

Open AccessArticle

Dynamic Construction Scheme for Virtualization Security Service in Software-Defined Networks

by Zhaowen Lin^1,2,3,†, Dan Tao^4,5,*,† and Zhenji Wang⁴

¹ Network and Information Center, Institute of Network Technology, Beijing University of Posts and Telecommunications, Beijing 100876, China

² Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory, Beijing University of Posts and Telecommunications, Beijing 100876, China

³ National Engineering Laboratory for Mobile Network Security, Beijing University of Posts and Telecommunications, Beijing 100876, China

⁴ School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing 100044, China

⁵ Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks, Nanjing 210003, China

^† These authors contributed equally to this work.

Sensors 2017, 17(4), 920; https://doi.org/10.3390/s17040920 - 21 Apr 2017

Cited by 13 | Viewed by 5386

Abstract

For a Software Defined Network (SDN), security is an important factor affecting its large-scale deployment. The existing security solutions for SDN mainly focus on the controller itself, which has to handle all the security protection tasks by using the programmability of the network. [...] Read more.

For a Software Defined Network (SDN), security is an important factor affecting its large-scale deployment. The existing security solutions for SDN mainly focus on the controller itself, which has to handle all the security protection tasks by using the programmability of the network. This will undoubtedly involve a heavy burden for the controller. More devastatingly, once the controller itself is attacked, the entire network will be paralyzed. Motivated by this, this paper proposes a novel security protection architecture for SDN. We design a security service orchestration center in the control plane of SDN, and this center physically decouples from the SDN controller and constructs SDN security services. We adopt virtualization technology to construct a security meta-function library, and propose a dynamic security service composition construction algorithm based on web service composition technology. The rule-combining method is used to combine security meta-functions to construct security services which meet the requirements of users. Moreover, the RETE algorithm is introduced to improve the efficiency of the rule-combining method. We evaluate our solutions in a realistic scenario based on OpenStack. Substantial experimental results demonstrate the effectiveness of our solutions that contribute to achieve the effective security protection with a small burden of the SDN controller. Full article

(This article belongs to the Special Issue New Advances in Identification, Information & Knowledge in the Internet of Things)

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17 pages, 2865 KiB

Open AccessArticle

A New Method for Single-Epoch Ambiguity Resolution with Indoor Pseudolite Positioning

by Xin Li^1,2, Peng Zhang^1,2,*, Jiming Guo^1,2

, Jinling Wang³ and Weining Qiu¹

¹ School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China

² Key Laboratory of Precise Engineering and Industry Surveying of National Administration of Surveying, Mapping and Geoinformation, Wuhan University, Wuhan 430079, China

³ School of Surveying and Spatial Information Systems, The University of New South Wales, 2052 Sydney, Australia

Sensors 2017, 17(4), 921; https://doi.org/10.3390/s17040921 - 21 Apr 2017

Cited by 32 | Viewed by 4886

Abstract

Ambiguity resolution (AR) is crucial for high-precision indoor pseudolite positioning. Due to the existing characteristics of the pseudolite positioning system, such as the geometry structure of the stationary pseudolite which is consistently invariant, the indoor signal is easy to interrupt and the first [...] Read more.

Ambiguity resolution (AR) is crucial for high-precision indoor pseudolite positioning. Due to the existing characteristics of the pseudolite positioning system, such as the geometry structure of the stationary pseudolite which is consistently invariant, the indoor signal is easy to interrupt and the first order linear truncation error cannot be ignored, and a new AR method based on the idea of the ambiguity function method (AFM) is proposed in this paper. The proposed method is a single-epoch and nonlinear method that is especially well-suited for indoor pseudolite positioning. Considering the very low computational efficiency of conventional AFM, we adopt an improved particle swarm optimization (IPSO) algorithm to search for the best solution in the coordinate domain, and variances of a least squares adjustment is conducted to ensure the reliability of the solving ambiguity. Several experiments, including static and kinematic tests, are conducted to verify the validity of the proposed AR method. Numerical results show that the IPSO significantly improved the computational efficiency of AFM and has a more elaborate search ability compared to the conventional grid searching method. For the indoor pseudolite system, which had an initial approximate coordinate precision better than 0.2 m, the AFM exhibited good performances in both static and kinematic tests. With the corrected ambiguity gained from our proposed method, indoor pseudolite positioning can achieve centimeter-level precision using a low-cost single-frequency software receiver. Full article

(This article belongs to the Section Physical Sensors)

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22 pages, 1389 KiB

Open AccessArticle

Zero-Sum Matrix Game with Payoffs of Dempster-Shafer Belief Structures and Its Applications on Sensors

by Xinyang Deng^*, Wen Jiang^*

and Jiandong Zhang

School of Electronics and Information, Northwestern Polytechnical University, Xi’an 710072, China

Sensors 2017, 17(4), 922; https://doi.org/10.3390/s17040922 - 21 Apr 2017

Cited by 43 | Viewed by 6761

Abstract

The zero-sum matrix game is one of the most classic game models, and it is widely used in many scientific and engineering fields. In the real world, due to the complexity of the decision-making environment, sometimes the payoffs received by players may be [...] Read more.

The zero-sum matrix game is one of the most classic game models, and it is widely used in many scientific and engineering fields. In the real world, due to the complexity of the decision-making environment, sometimes the payoffs received by players may be inexact or uncertain, which requires that the model of matrix games has the ability to represent and deal with imprecise payoffs. To meet such a requirement, this paper develops a zero-sum matrix game model with Dempster–Shafer belief structure payoffs, which effectively represents the ambiguity involved in payoffs of a game. Then, a decomposition method is proposed to calculate the value of such a game, which is also expressed with belief structures. Moreover, for the possible computation-intensive issue in the proposed decomposition method, as an alternative solution, a Monte Carlo simulation approach is presented, as well. Finally, the proposed zero-sum matrix games with payoffs of Dempster–Shafer belief structures is illustratively applied to the sensor selection and intrusion detection of sensor networks, which shows its effectiveness and application process. Full article

(This article belongs to the Special Issue Soft Sensors and Intelligent Algorithms for Data Fusion)

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12 pages, 2516 KiB

Open AccessArticle

A Novel Method of Localization for Moving Objects with an Alternating Magnetic Field

by Xiang Gao^1,*, Shenggang Yan¹ and Bin Li^1,2

¹ School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China

² Key Laboratory of Ocean Acoustics and Sensing, Ministry of Industry and Information Technology, Xi’an 710072, China

Sensors 2017, 17(4), 923; https://doi.org/10.3390/s17040923 - 21 Apr 2017

Cited by 22 | Viewed by 4671

Abstract

Magnetic detection technology has wide applications in the fields of geological exploration, biomedical treatment, wreck removal and localization of unexploded ordinance. A large number of methods have been developed to locate targets with static magnetic fields, however, the relation between the problem of [...] Read more.

Magnetic detection technology has wide applications in the fields of geological exploration, biomedical treatment, wreck removal and localization of unexploded ordinance. A large number of methods have been developed to locate targets with static magnetic fields, however, the relation between the problem of localization of moving objectives with alternating magnetic fields and the localization with a static magnetic field is rarely studied. A novel method of target localization based on coherent demodulation was proposed in this paper. The problem of localization of moving objects with an alternating magnetic field was transformed into the localization with a static magnetic field. The Levenberg-Marquardt (L-M) algorithm was applied to calculate the position of the target with magnetic field data measured by a single three-component magnetic sensor. Theoretical simulation and experimental results demonstrate the effectiveness of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 3015 KiB

Open AccessArticle

State Estimation Using Dependent Evidence Fusion: Application to Acoustic Resonance-Based Liquid Level Measurement

by Xiaobin Xu^1,*, Zhenghui Li¹, Guo Li¹ and Zhe Zhou²

¹ School of Automation, Hangzhou Dianzi University, Hangzhou 310018, China

² School of Engineering, Huzhou University, Huzhou 310027, China

Sensors 2017, 17(4), 924; https://doi.org/10.3390/s17040924 - 21 Apr 2017

Cited by 5 | Viewed by 4349

Abstract

Estimating the state of a dynamic system via noisy sensor measurement is a common problem in sensor methods and applications. Most state estimation methods assume that measurement noise and state perturbations can be modeled as random variables with known statistical properties. However in [...] Read more.

Estimating the state of a dynamic system via noisy sensor measurement is a common problem in sensor methods and applications. Most state estimation methods assume that measurement noise and state perturbations can be modeled as random variables with known statistical properties. However in some practical applications, engineers can only get the range of noises, instead of the precise statistical distributions. Hence, in the framework of Dempster-Shafer (DS) evidence theory, a novel state estimatation method by fusing dependent evidence generated from state equation, observation equation and the actual observations of the system states considering bounded noises is presented. It can be iteratively implemented to provide state estimation values calculated from fusion results at every time step. Finally, the proposed method is applied to a low-frequency acoustic resonance level gauge to obtain high-accuracy measurement results. Full article

(This article belongs to the Special Issue Advances in Multi-Sensor Information Fusion: Theory and Applications 2017)

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9 pages, 2584 KiB

Open AccessArticle

Imaging of the Finger Vein and Blood Flow for Anti-Spoofing Authentication Using a Laser and a MEMS Scanner

by Jaekwon Lee¹, Seunghwan Moon¹, Juhun Lim², Min-Joo Gwak³, Jae Gwan Kim²

, Euiheon Chung² and Jong-Hyun Lee^1,2,*

¹ School of Mechanical Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea

² Department of Biomedical Science & Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea

³ Fiber Optic Electronic R&D Center, Korea Optron Corporation (KOC), Gwangju 61007, Korea

Sensors 2017, 17(4), 925; https://doi.org/10.3390/s17040925 - 22 Apr 2017

Cited by 19 | Viewed by 8725

Abstract

A new authentication method employing a laser and a scanner is proposed to improve image contrast of the finger vein and to extract blood flow pattern for liveness detection. A micromirror reflects a laser beam and performs a uniform raster scan. Transmissive vein [...] Read more.

A new authentication method employing a laser and a scanner is proposed to improve image contrast of the finger vein and to extract blood flow pattern for liveness detection. A micromirror reflects a laser beam and performs a uniform raster scan. Transmissive vein images were obtained, and compared with those of an LED. Blood flow patterns were also obtained based on speckle images in perfusion and occlusion. Curvature ratios of the finger vein and blood flow intensities were found to be nearly constant, regardless of the vein size, which validated the high repeatability of this scheme for identity authentication with anti-spoofing. Full article

(This article belongs to the Section Biosensors)

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15 pages, 2615 KiB

Open AccessArticle

Experimental Demonstration and Circuitry for a Very Compact Coil-Only Pulse Echo EMAT

by Dirk Rueter

Institute of Measuring and Sensor Technology, University of Applied Sciences Ruhr-West, 45479 Muelheim, Germany

Sensors 2017, 17(4), 926; https://doi.org/10.3390/s17040926 - 22 Apr 2017

Cited by 11 | Viewed by 8160

Abstract

This experimental study demonstrates for the first time a solid-state circuitry and design for a simple compact copper coil (without an additional bulky permanent magnet or bulky electromagnet) as a contactless electromagnetic acoustic transducer (EMAT) for pulse echo operation at MHz frequencies. A [...] Read more.

This experimental study demonstrates for the first time a solid-state circuitry and design for a simple compact copper coil (without an additional bulky permanent magnet or bulky electromagnet) as a contactless electromagnetic acoustic transducer (EMAT) for pulse echo operation at MHz frequencies. A pulsed ultrasound emission into a metallic test object is electromagnetically excited by an intense MHz burst at up to 500 A through the 0.15 mm filaments of the transducer. Immediately thereafter, a smoother and quasi “DC-like” current of 100 A is applied for about 1 ms and allows an echo detection. The ultrasonic pulse echo operation for a simple, compact, non-contacting copper coil is new. Application scenarios for compact transducer techniques include very narrow and hostile environments, in which, e.g., quickly moving metal parts must be tested with only one, non-contacting ultrasound shot. The small transducer coil can be operated remotely with a cable connection, separate from the much bulkier supply circuitry. Several options for more technical and fundamental progress are discussed. Full article

(This article belongs to the Special Issue Acoustic Sensing and Ultrasonic Drug Delivery)

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21 pages, 3928 KiB

Open AccessArticle

The Use of IMMUs in a Water Environment: Instrument Validation and Application of 3D Multi-Body Kinematic Analysis in Medicine and Sport

by Anna Lisa Mangia¹

, Matteo Cortesi²

, Silvia Fantozzi^1,3,*

, Andrea Giovanardi⁴, Davide Borra³

and Giorgio Gatta²

¹ Health Sciences and Technologies—Interdepartmental Centre for Industrial Research, University of Bologna, Via Tolara di Sopra, 50, 40064 Ozzano dell’Emilia, Italy

² Department for Life Quality Studies, University of Bologna, C.so D’Augusto, 237, 47921 Rimini, Italy

³ Department of Electrical, Electronic and Information Engineering, University of Bologna, Viale del Risorgimento, 2, 40136 Bologna, Italy

⁴ School of Pharmacy, Biotechnology and Sport Science, University of Bologna, Viale Berti Pichat 10, 40127 Bologna, Italy

Sensors 2017, 17(4), 927; https://doi.org/10.3390/s17040927 - 22 Apr 2017

Cited by 22 | Viewed by 6923

Abstract

The aims of the present study were the instrumental validation of inertial-magnetic measurements units (IMMUs) in water, and the description of their use in clinical and sports aquatic applications applying customized 3D multi-body models. Firstly, several tests were performed to map the magnetic [...] Read more.

The aims of the present study were the instrumental validation of inertial-magnetic measurements units (IMMUs) in water, and the description of their use in clinical and sports aquatic applications applying customized 3D multi-body models. Firstly, several tests were performed to map the magnetic field in the swimming pool and to identify the best volume for experimental test acquisition with a mean dynamic orientation error lower than 5°. Successively, the gait and the swimming analyses were explored in terms of spatiotemporal and joint kinematics variables. The extraction of only spatiotemporal parameters highlighted several critical issues and the joint kinematic information has shown to be an added value for both rehabilitative and sport training purposes. Furthermore, 3D joint kinematics applied using the IMMUs provided similar quantitative information than that of more expensive and bulky systems but with a simpler and faster setup preparation, a lower time consuming processing phase, as well as the possibility to record and analyze a higher number of strides/strokes without limitations imposed by the cameras. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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15 pages, 337 KiB

Open AccessArticle

A Weighted Belief Entropy-Based Uncertainty Measure for Multi-Sensor Data Fusion

by Yongchuan Tang^*

, Deyun Zhou, Shuai Xu and Zichang He

School of Electronics and Information, Northwestern Polytechnical University, Xi’an 710072, China

Sensors 2017, 17(4), 928; https://doi.org/10.3390/s17040928 - 22 Apr 2017

Cited by 87 | Viewed by 7272

Abstract

In real applications, how to measure the uncertain degree of sensor reports before applying sensor data fusion is a big challenge. In this paper, in the frame of Dempster–Shafer evidence theory, a weighted belief entropy based on Deng entropy is proposed to quantify [...] Read more.

In real applications, how to measure the uncertain degree of sensor reports before applying sensor data fusion is a big challenge. In this paper, in the frame of Dempster–Shafer evidence theory, a weighted belief entropy based on Deng entropy is proposed to quantify the uncertainty of uncertain information. The weight of the proposed belief entropy is based on the relative scale of a proposition with regard to the frame of discernment (FOD). Compared with some other uncertainty measures in Dempster–Shafer framework, the new measure focuses on the uncertain information represented by not only the mass function, but also the scale of the FOD, which means less information loss in information processing. After that, a new multi-sensor data fusion approach based on the weighted belief entropy is proposed. The rationality and superiority of the new multi-sensor data fusion method is verified according to an experiment on artificial data and an application on fault diagnosis of a motor rotor. Full article

(This article belongs to the Special Issue Soft Sensors and Intelligent Algorithms for Data Fusion)

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11 pages, 4162 KiB

Open AccessArticle

A Miniature Aerosol Sensor for Detecting Polydisperse Airborne Ultrafine Particles

by Chao Zhang¹, Dingqu Wang², Rong Zhu^1,*, Wenming Yang³ and Peng Jiang¹

¹ State Key Laboratory of Precision Measurement Technology and Instrument, Department of Precision Instrument, Tsinghua University, Beijing 100084, China

² Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China

³ School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China

Sensors 2017, 17(4), 929; https://doi.org/10.3390/s17040929 - 22 Apr 2017

Cited by 16 | Viewed by 6528

Abstract

Counting and sizing of polydisperse airborne nanoparticles have attracted most attentions owing to increasing widespread presence of airborne engineered nanoparticles or ultrafine particles. Here we report a miniature aerosol sensor to detect particle size distribution of polydisperse ultrafine particles based on ion diffusion [...] Read more.

Counting and sizing of polydisperse airborne nanoparticles have attracted most attentions owing to increasing widespread presence of airborne engineered nanoparticles or ultrafine particles. Here we report a miniature aerosol sensor to detect particle size distribution of polydisperse ultrafine particles based on ion diffusion charging and electrical detection. The aerosol sensor comprises a couple of planar electrodes printed on two circuit boards assembled in parallel, where charging, precipitation and measurement sections are integrated into one chip, which can detect aerosol particle size in of 30–500 nm, number concentration in range of 5 × 10² – 5 × 10⁷ /cm³. The average relative errors of the measured aerosol number concentration and the particle size are estimated to be 12.2% and 13.5% respectively. A novel measurement scheme is proposed to actualize a real-time detection of polydisperse particles by successively modulating the measurement voltage and deducing the particle size distribution through a smart data fusion algorithm. The effectiveness of the aerosol sensor is experimentally demonstrated via measurements of polystyrene latex (PSL) aerosol and nucleic acid aerosol, as well as sodium chloride aerosol particles. Full article

(This article belongs to the Section Chemical Sensors)

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21 pages, 1230 KiB

Open AccessArticle

Simulation Study of the Localization of a Near-Surface Crack Using an Air-Coupled Ultrasonic Sensor Array

by Steven Delrue^1,*

, Vladislav Aleshin², Mikael Sørensen^3,4 and Lieven De Lathauwer^3,4

¹ Wave Propagation and Signal Processing Research Group, KU Leuven Kulak, 8500 Kortrijk, Belgium

² Joint International Laboratory LICS/LEMAC, Institute of Electronics, Microelectronics and Nanotechnologies, UMR CNRS 8520, 59 652 Villeneuve d’Ascq CEDEX, France

³ Group Science, Engineering and Technology, KU Leuven Kulak, 8500 Kortrijk, Belgium

⁴ Department of Electrical Engineering (ESAT), STADIUS, KU Leuven, 3001 Leuven-Heverlee, Belgium;

Sensors 2017, 17(4), 930; https://doi.org/10.3390/s17040930 - 22 Apr 2017

Cited by 8 | Viewed by 5781

Abstract

The importance of Non-Destructive Testing (NDT) to check the integrity of materials in different fields of industry has increased significantly in recent years. Actually, industry demands NDT methods that allow fast (preferably non-contact) detection and localization of early-stage defects with easy-to-interpret results, so [...] Read more.

The importance of Non-Destructive Testing (NDT) to check the integrity of materials in different fields of industry has increased significantly in recent years. Actually, industry demands NDT methods that allow fast (preferably non-contact) detection and localization of early-stage defects with easy-to-interpret results, so that even a non-expert field worker can carry out the testing. The main challenge is to combine as many of these requirements into one single technique. The concept of acoustic cameras, developed for low frequency NDT, meets most of the above-mentioned requirements. These cameras make use of an array of microphones to visualize noise sources by estimating the Direction Of Arrival (DOA) of the impinging sound waves. Until now, however, because of limitations in the frequency range and the lack of integrated nonlinear post-processing, acoustic camera systems have never been used for the localization of incipient damage. The goal of the current paper is to numerically investigate the capabilities of locating incipient damage by measuring the nonlinear airborne emission of the defect using a non-contact ultrasonic sensor array. We will consider a simple case of a sample with a single near-surface crack and prove that after efficient excitation of the defect sample, the nonlinear defect responses can be detected by a uniform linear sensor array. These responses are then used to determine the location of the defect by means of three different DOA algorithms. The results obtained in this study can be considered as a first step towards the development of a nonlinear ultrasonic camera system, comprising the ultrasonic sensor array as the hardware and nonlinear post-processing and source localization software. Full article

(This article belongs to the Special Issue Sensor Technologies for Health Monitoring of Composite Structures)

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21 pages, 1153 KiB

Open AccessArticle

Smartphone Location-Independent Physical Activity Recognition Based on Transportation Natural Vibration Analysis

by Taeho Hur¹

, Jaehun Bang¹

, Dohyeong Kim¹, Oresti Banos²

and Sungyoung Lee^1,*

¹ Department of Computer Science and Engineering, Kyung Hee University, (Global Campus), 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, Korea

² Telemedicine Cluster of the Biomedical Signals and Systems Group, University of Twente, Enschede 7500AE, The Netherlands

Sensors 2017, 17(4), 931; https://doi.org/10.3390/s17040931 - 23 Apr 2017

Cited by 18 | Viewed by 6701

Abstract

Activity recognition through smartphones has been proposed for a variety of applications. The orientation of the smartphone has a significant effect on the recognition accuracy; thus, researchers generally propose using features invariant to orientation or displacement to achieve this goal. However, those features [...] Read more.

Activity recognition through smartphones has been proposed for a variety of applications. The orientation of the smartphone has a significant effect on the recognition accuracy; thus, researchers generally propose using features invariant to orientation or displacement to achieve this goal. However, those features reduce the capability of the recognition system to differentiate among some specific commuting activities (e.g., bus and subway) that normally involve similar postures. In this work, we recognize those activities by analyzing the vibrations of the vehicle in which the user is traveling. We extract natural vibration features of buses and subways to distinguish between them and address the confusion that can arise because the activities are both static in terms of user movement. We use the gyroscope to fix the accelerometer to the direction of gravity to achieve an orientation-free use of the sensor. We also propose a correction algorithm to increase the accuracy when used in free living conditions and a battery saving algorithm to consume less power without reducing performance. Our experimental results show that the proposed system can adequately recognize each activity, yielding better accuracy in the detection of bus and subway activities than existing methods. Full article

(This article belongs to the Special Issue Smartphone-based Pedestrian Localization and Navigation)

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17 pages, 1527 KiB

Open AccessArticle

Implementation Issues of Adaptive Energy Detection in Heterogeneous Wireless Networks

by Iker Sobron^1,*

, Iñaki Eizmendi¹, Wallace A. Martins², Paulo S. R. Diniz²

, Juan Luis Ordiales¹ and Manuel Velez¹

¹ University of the Basque Country UPV/EHU, 48013 Bilbao, Spain

² Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro 21941-972, Brazil

Sensors 2017, 17(4), 932; https://doi.org/10.3390/s17040932 - 23 Apr 2017

Cited by 1 | Viewed by 4847

Abstract

Spectrum sensing (SS) enables the coexistence of non-coordinated heterogeneous wireless systems operating in the same band. Due to its computational simplicity, energy detection (ED) technique has been widespread employed in SS applications; nonetheless, the conventional ED may be unreliable under environmental impairments, justifying [...] Read more.

Spectrum sensing (SS) enables the coexistence of non-coordinated heterogeneous wireless systems operating in the same band. Due to its computational simplicity, energy detection (ED) technique has been widespread employed in SS applications; nonetheless, the conventional ED may be unreliable under environmental impairments, justifying the use of ED-based variants. Assessing ED algorithms from theoretical and simulation viewpoints relies on several assumptions and simplifications which, eventually, lead to conclusions that do not necessarily meet the requirements imposed by real propagation environments. This work addresses those problems by dealing with practical implementation issues of adaptive least mean square (LMS)-based ED algorithms. The paper proposes a new adaptive ED algorithm that uses a variable step-size guaranteeing the LMS convergence in time-varying environments. Several implementation guidelines are provided and, additionally, an empirical assessment and validation with a software defined radio-based hardware is carried out. Experimental results show good performance in terms of probabilities of detection (

P_{d} > 0.9

) and false alarm (

P_{f} \sim 0.05

) in a range of low signal-to-noise ratios around

[- 4, 1]

dB, in both single-node and cooperative modes. The proposed sensing methodology enables a seamless monitoring of the radio electromagnetic spectrum in order to provide band occupancy information for an efficient usage among several wireless communications systems. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2016)

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12 pages, 2730 KiB

Open AccessArticle

Using Wavelet Packet Transform for Surface Roughness Evaluation and Texture Extraction

by Xiao Wang

, Tielin Shi, Guanglan Liao^*, Yichun Zhang

, Yuan Hong and Kepeng Chen

State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430000, China

Sensors 2017, 17(4), 933; https://doi.org/10.3390/s17040933 - 23 Apr 2017

Cited by 48 | Viewed by 6862

Abstract

Surface characterization plays a significant role in evaluating surface functional performance. In this paper, we introduce wavelet packet transform for surface roughness characterization and surface texture extraction. Surface topography is acquired by a confocal laser scanning microscope. Smooth border padding and de-noise process [...] Read more.

Surface characterization plays a significant role in evaluating surface functional performance. In this paper, we introduce wavelet packet transform for surface roughness characterization and surface texture extraction. Surface topography is acquired by a confocal laser scanning microscope. Smooth border padding and de-noise process are implemented to generate a roughness surface precisely. By analyzing the high frequency components of a simulated profile, surface textures are separated by using wavelet packet transform, and the reconstructed roughness and waviness coincide well with the original ones. Wavelet packet transform is then used as a smooth filter for texture extraction. A roughness specimen and three real engineering surfaces are also analyzed in detail. Profile and areal roughness parameters are calculated to quantify the characterization results and compared with those measured by a profile meter. Most obtained roughness parameters agree well with the measurement results, and the largest deviation occurs in the skewness. The relations between the roughness parameters and noise are analyzed by simulation for explaining the relatively large deviations. The extracted textures reflect the surface structure and indicate the manufacturing conditions well, which is helpful for further feature recognition and matching. By using wavelet packet transform, engineering surfaces are comprehensively characterized including evaluating surface roughness and extracting surface texture. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 3749 KiB

Open AccessArticle

Convergent Validity of a Wearable Sensor System for Measuring Sub-Task Performance during the Timed Up-and-Go Test

by James Beyea¹, Chris A. McGibbon^1,2,*, Andrew Sexton², Jeremy Noble¹ and Colleen O’Connell^1,3

¹ Faculty of Kinesiology, University of New Brunswick, Fredericton, NB E3B5A3, Canada

² Institute of Biomedical Engineering, University of New Brunswick, Fredericton, NB E3B5A3, Canada

³ Stan Cassidy Centre for Rehabilitation, Fredericton, NB E3BOC7, Canada

Sensors 2017, 17(4), 934; https://doi.org/10.3390/s17040934 - 23 Apr 2017

Cited by 62 | Viewed by 7503

Abstract

Background: The timed-up-and-go test (TUG) is one of the most commonly used tests of physical function in clinical practice and for research outcomes. Inertial sensors have been used to parse the TUG test into its composite phases (rising, walking, turning, etc.), but have [...] Read more.

Background: The timed-up-and-go test (TUG) is one of the most commonly used tests of physical function in clinical practice and for research outcomes. Inertial sensors have been used to parse the TUG test into its composite phases (rising, walking, turning, etc.), but have not validated this approach against an optoelectronic gold-standard, and to our knowledge no studies have published the minimal detectable change of these measurements. Methods: Eleven adults performed the TUG three times each under normal and slow walking conditions, and 3 m and 5 m walking distances, in a 12-camera motion analysis laboratory. An inertial measurement unit (IMU) with tri-axial accelerometers and gyroscopes was worn on the upper-torso. Motion analysis marker data and IMU signals were analyzed separately to identify the six main TUG phases: sit-to-stand, 1st walk, 1st turn, 2nd walk, 2nd turn, and stand-to-sit, and the absolute agreement between two systems analyzed using intra-class correlation (ICC, model 2) analysis. The minimal detectable change (MDC) within subjects was also calculated for each TUG phase. Results: The overall difference between TUG sub-tasks determined using 3D motion capture data and the IMU sensor data was <0.5 s. For all TUG distances and speeds, the absolute agreement was high for total TUG time and walk times (ICC > 0.90), but less for chair activity (ICC range 0.5–0.9) and typically poor for the turn time (ICC < 0.4). MDC values for total TUG time ranged between 2–4 s or 12–22% of the TUG time measurement. MDC of the sub-task times were higher proportionally, being 20–60% of the sub-task duration. Conclusions: We conclude that a commercial IMU can be used for quantifying the TUG phases with accuracy sufficient for clinical applications; however, the MDC when using inertial sensors is not necessarily improved over less sophisticated measurement tools. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications)

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10 pages, 2701 KiB

Open AccessArticle

Improved Line Tracing Methods for Removal of Bad Streaks Noise in CCD Line Array Image—A Case Study with GF-1 Images

by Bo Wang^1,*, Jianwei Bao¹, Shikui Wang², Houjun Wang³ and Qinghong Sheng¹

¹ College of Astronautics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China

² Tianjin Key Laboratory of Intelligent Information Processing in Remote Sensing, Tianjin 300301, China

³ National Ocean Technology Center, Tianjin 300112, China

Sensors 2017, 17(4), 935; https://doi.org/10.3390/s17040935 - 24 Apr 2017

Cited by 5 | Viewed by 4561

Abstract

Remote sensing images could provide us with tremendous quantities of large-scale information. Noise artifacts (stripes), however, made the images inappropriate for vitalization and batch process. An effective restoration method would make images ready for further analysis. In this paper, a new method is [...] Read more.

Remote sensing images could provide us with tremendous quantities of large-scale information. Noise artifacts (stripes), however, made the images inappropriate for vitalization and batch process. An effective restoration method would make images ready for further analysis. In this paper, a new method is proposed to correct the stripes and bad abnormal pixels in charge-coupled device (CCD) linear array images. The method involved a line tracing method, limiting the location of noise to a rectangular region, and corrected abnormal pixels with the Lagrange polynomial algorithm. The proposed detection and restoration method were applied to Gaofen-1 satellite (GF-1) images, and the performance of this method was evaluated by omission ratio and false detection ratio, which reached 0.6% and 0%, respectively. This method saved 55.9% of the time, compared with traditional method. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 3372 KiB

Open AccessArticle

Probabilistic Fatigue Life Updating for Railway Bridges Based on Local Inspection and Repair

by Young-Joo Lee¹, Robin E. Kim², Wonho Suh^3,* and Kiwon Park⁴

¹ School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Korea

² Fire Research Institute, Korea Institute of Civil Engineering and Building Technology, Hwaseong 18544, Korea

³ Department of Transportation and Logistics Engineering, Hanyang University ERICA Campus, Ansan 15588, Korea

⁴ Department of Mechanical and Aerospace Engineering, Trine University, Angola, IN 46703, USA

Sensors 2017, 17(4), 936; https://doi.org/10.3390/s17040936 - 24 Apr 2017

Cited by 19 | Viewed by 5494

Abstract

Railway bridges are exposed to repeated train loads, which may cause fatigue failure. As critical links in a transportation network, railway bridges are expected to survive for a target period of time, but sometimes they fail earlier than expected. To guarantee the target [...] Read more.

Railway bridges are exposed to repeated train loads, which may cause fatigue failure. As critical links in a transportation network, railway bridges are expected to survive for a target period of time, but sometimes they fail earlier than expected. To guarantee the target bridge life, bridge maintenance activities such as local inspection and repair should be undertaken properly. However, this is a challenging task because there are various sources of uncertainty associated with aging bridges, train loads, environmental conditions, and maintenance work. Therefore, to perform optimal risk-based maintenance of railway bridges, it is essential to estimate the probabilistic fatigue life of a railway bridge and update the life information based on the results of local inspections and repair. Recently, a system reliability approach was proposed to evaluate the fatigue failure risk of structural systems and update the prior risk information in various inspection scenarios. However, this approach can handle only a constant-amplitude load and has limitations in considering a cyclic load with varying amplitude levels, which is the major loading pattern generated by train traffic. In addition, it is not feasible to update the prior risk information after bridges are repaired. In this research, the system reliability approach is further developed so that it can handle a varying-amplitude load and update the system-level risk of fatigue failure for railway bridges after inspection and repair. The proposed method is applied to a numerical example of an in-service railway bridge, and the effects of inspection and repair on the probabilistic fatigue life are discussed. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 8812 KiB

Open AccessArticle

Improving Passive Time Reversal Underwater Acoustic Communications Using Subarray Processing

by Chengbing He^*, Lianyou Jing, Rui Xi, Qinyuan Li and Qunfei Zhang

School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China

Sensors 2017, 17(4), 937; https://doi.org/10.3390/s17040937 - 24 Apr 2017

Cited by 12 | Viewed by 5228

Abstract

Multichannel receivers are usually employed in high-rate underwater acoustic communication to achieve spatial diversity. In the context of multichannel underwater acoustic communications, passive time reversal (TR) combined with a single-channel adaptive decision feedback equalizer (TR-DFE) is a low-complexity solution to achieve both spatial [...] Read more.

Multichannel receivers are usually employed in high-rate underwater acoustic communication to achieve spatial diversity. In the context of multichannel underwater acoustic communications, passive time reversal (TR) combined with a single-channel adaptive decision feedback equalizer (TR-DFE) is a low-complexity solution to achieve both spatial and temporal focusing. In this paper, we present a novel receiver structure to combine passive time reversal with a low-order multichannel adaptive decision feedback equalizer (TR-MC-DFE) to improve the performance of the conventional TR-DFE. First, the proposed method divides the whole received array into several subarrays. Second, we conduct passive time reversal processing in each subarray. Third, the multiple subarray outputs are equalized with a low-order multichannel DFE. We also investigated different channel estimation methods, including least squares (LS), orthogonal matching pursuit (OMP), and improved proportionate normalized least mean squares (IPNLMS). The bit error rate (BER) and output signal-to-noise ratio (SNR) performances of the receiver algorithms are evaluated using simulation and real data collected in a lake experiment. The source-receiver range is 7.4 km, and the data rate with quadrature phase shift keying (QPSK) signal is 8 kbits/s. The uncoded BER of the single input multiple output (SIMO) systems varies between

1 \times 10^{- 1}

and

2 \times 10^{- 2}

for the conventional TR-DFE, and between

1 \times 10^{- 2}

and

1 \times 10^{- 3}

for the proposed TR-MC-DFE when eight hydrophones are utilized. Compared to conventional TR-DFE, the average output SNR of the experimental data is enhanced by 3 dB. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 810 KiB

Open AccessArticle

Direction of Arrival Estimation for MIMO Radar via Unitary Nuclear Norm Minimization

by Xianpeng Wang^1,2, Mengxing Huang^1,2,*, Xiaoqin Wu^1,2 and Guoan Bi³

¹ State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou 570228, China

² College of Information Science and Technology, Hainan University, Haikou 570228, China

³ School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore

Sensors 2017, 17(4), 939; https://doi.org/10.3390/s17040939 - 24 Apr 2017

Cited by 14 | Viewed by 6276

Abstract

In this paper, we consider the direction of arrival (DOA) estimation issue of noncircular (NC) source in multiple-input multiple-output (MIMO) radar and propose a novel unitary nuclear norm minimization (UNNM) algorithm. In the proposed method, the noncircular properties of signals are used to [...] Read more.

In this paper, we consider the direction of arrival (DOA) estimation issue of noncircular (NC) source in multiple-input multiple-output (MIMO) radar and propose a novel unitary nuclear norm minimization (UNNM) algorithm. In the proposed method, the noncircular properties of signals are used to double the virtual array aperture, and the real-valued data are obtained by utilizing unitary transformation. Then a real-valued block sparse model is established based on a novel over-complete dictionary, and a UNNM algorithm is formulated for recovering the block-sparse matrix. In addition, the real-valued NC-MUSIC spectrum is used to design a weight matrix for reweighting the nuclear norm minimization to achieve the enhanced sparsity of solutions. Finally, the DOA is estimated by searching the non-zero blocks of the recovered matrix. Because of using the noncircular properties of signals to extend the virtual array aperture and an additional real structure to suppress the noise, the proposed method provides better performance compared with the conventional sparse recovery based algorithms. Furthermore, the proposed method can handle the case of underdetermined DOA estimation. Simulation results show the effectiveness and advantages of the proposed method. Full article

(This article belongs to the Special Issue Recent Advances in Array Signal Processing and Its Applications in IoT Security)

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Review

Jump to: Research, Other

19 pages, 2663 KiB

Open AccessReview

Electrodes for Semiconductor Gas Sensors

by Sung Pil Lee

Department of Electronic Engineering, Kyungnam University, 7 Kyungnamdaehak-ro, Masanhappo-gu, Changwon 51767, Korea

Sensors 2017, 17(4), 683; https://doi.org/10.3390/s17040683 - 25 Mar 2017

Cited by 78 | Viewed by 19370

Abstract

The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and [...] Read more.

The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode–semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode–semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect. Full article

(This article belongs to the Collection Gas Sensors)

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24 pages, 9209 KiB

Open AccessReview

Molecular Imprinting Applications in Forensic Science

by Erkut Yılmaz¹, Bora Garipcan², Hirak K. Patra³ and Lokman Uzun^4,*

¹ Department of Biotechnology and Molecular Biology, Aksaray University, 68100 Aksaray, Turkey

² Institute of Biomedical Engineering, Bogazici University, 34684 Istanbul, Turkey

³ Department of Clinical and Experimental Medicine, Linkoping University, 58225 Linköping, Sweden

⁴ Department of Chemistry, Hacettepe University, 06381 Ankara, Turkey

Sensors 2017, 17(4), 691; https://doi.org/10.3390/s17040691 - 28 Mar 2017

Cited by 34 | Viewed by 9628

Abstract

Producing molecular imprinting-based materials has received increasing attention due to recognition selectivity, stability, cast effectiveness, and ease of production in various forms for a wide range of applications. The molecular imprinting technique has a variety of applications in the areas of the food [...] Read more.

Producing molecular imprinting-based materials has received increasing attention due to recognition selectivity, stability, cast effectiveness, and ease of production in various forms for a wide range of applications. The molecular imprinting technique has a variety of applications in the areas of the food industry, environmental monitoring, and medicine for diverse purposes like sample pretreatment, sensing, and separation/purification. A versatile usage, stability and recognition capabilities also make them perfect candidates for use in forensic sciences. Forensic science is a demanding area and there is a growing interest in molecularly imprinted polymers (MIPs) in this field. In this review, recent molecular imprinting applications in the related areas of forensic sciences are discussed while considering the literature of last two decades. Not only direct forensic applications but also studies of possible forensic value were taken into account like illicit drugs, banned sport drugs, effective toxins and chemical warfare agents in a review of over 100 articles. The literature was classified according to targets, material shapes, production strategies, detection method, and instrumentation. We aimed to summarize the current applications of MIPs in forensic science and put forth a projection of their potential uses as promising alternatives for benchmark competitors. Full article

(This article belongs to the Special Issue Biosensors and Molecular Imprinting)

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15 pages, 3088 KiB

Open AccessReview

Imprinting of Microorganisms for Biosensor Applications

by Neslihan Idil^1,* and Bo Mattiasson^2,3

¹ Department of Biology, Faculty of Sciences, Hacettepe University, 06800 Ankara, Turkey

² Department of Biotechnology, Lund University, 22362 Lund, Sweden

³ CapSenze Biosystems AB, 22363 Lund, Sweden

Sensors 2017, 17(4), 708; https://doi.org/10.3390/s17040708 - 29 Mar 2017

Cited by 51 | Viewed by 8086

Abstract

There is a growing need for selective recognition of microorganisms in complex samples due to the rapidly emerging importance of detecting them in various matrices. Most of the conventional methods used to identify microorganisms are time-consuming, laborious and expensive. In recent years, many [...] Read more.

There is a growing need for selective recognition of microorganisms in complex samples due to the rapidly emerging importance of detecting them in various matrices. Most of the conventional methods used to identify microorganisms are time-consuming, laborious and expensive. In recent years, many efforts have been put forth to develop alternative methods for the detection of microorganisms. These methods include use of various components such as silica nanoparticles, microfluidics, liquid crystals, carbon nanotubes which could be integrated with sensor technology in order to detect microorganisms. In many of these publications antibodies were used as recognition elements by means of specific interactions between the target cell and the binding site of the antibody for the purpose of cell recognition and detection. Even though natural antibodies have high selectivity and sensitivity, they have limited stability and tend to denature in conditions outside the physiological range. Among different approaches, biomimetic materials having superior properties have been used in creating artificial systems. Molecular imprinting is a well suited technique serving the purpose to develop highly selective sensing devices. Molecularly imprinted polymers defined as artificial recognition elements are of growing interest for applications in several sectors of life science involving the investigations on detecting molecules of specific interest. These polymers have attractive properties such as high bio-recognition capability, mechanical and chemical stability, easy preparation and low cost which make them superior over natural recognition reagents. This review summarizes the recent advances in the detection and quantification of microorganisms by emphasizing the molecular imprinting technology and its applications in the development of sensor strategies. Full article

(This article belongs to the Special Issue Biosensors and Molecular Imprinting)

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27 pages, 6239 KiB

Open AccessFeature PaperReview

Metal Oxide Gas Sensors, a Survey of Selectivity Issues Addressed at the SENSOR Lab, Brescia (Italy)

by Andrea Ponzoni^1,2,*, Camilla Baratto^1,2, Nicola Cattabiani^1,2, Matteo Falasconi^1,2, Vardan Galstyan^1,2

, Estefania Nunez-Carmona^1,2

, Federica Rigoni^1,2, Veronica Sberveglieri³

, Giulia Zambotti^1,2 and Dario Zappa^1,2

¹ Consiglio Nazionale delle Ricerche (CNR), Istituto Nazionale di Ottica (INO), Unità di Brescia SENSOR Lab, Via Branze 45, 25123 Brescia, Italy

² Dipartimento di Ingegneria dell’Informazione, Università degli Studi di Brescia, SENSOR Lab, Via Valotti 9, 25133 Brescia, Italy

³ Consiglio Nazionale delle Ricerche (CNR), Istituto di Bioscienze e Biorisorse (IBBR), Via Madonna del Piano, 10, 50019 Sesto Fiorentino (FI), Italy

Sensors 2017, 17(4), 714; https://doi.org/10.3390/s17040714 - 29 Mar 2017

Cited by 142 | Viewed by 18864

Abstract

This work reports the recent results achieved at the SENSOR Lab, Brescia (Italy) to address the selectivity of metal oxide based gas sensors. In particular, two main strategies are being developed for this purpose: (i) investigating different sensing mechanisms featuring different response spectra [...] Read more.

This work reports the recent results achieved at the SENSOR Lab, Brescia (Italy) to address the selectivity of metal oxide based gas sensors. In particular, two main strategies are being developed for this purpose: (i) investigating different sensing mechanisms featuring different response spectra that may be potentially integrated in a single device; (ii) exploiting the electronic nose (EN) approach. The former has been addressed only recently and activities are mainly focused on determining the most suitable configuration and measurements to exploit the novel mechanism. Devices suitable to exploit optical (photoluminescence), magnetic (magneto-optical Kerr effect) and surface ionization in addition to the traditional chemiresistor device are here discussed together with the sensing performance measured so far. The electronic nose is a much more consolidated technology, and results are shown concerning its suitability to respond to industrial and societal needs in the fields of food quality control and detection of microbial activity in human sweat. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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19 pages, 1648 KiB

Open AccessFeature PaperReview

MIP-Based Sensors: Promising New Tools for Cancer Biomarker Determination

by Giulia Selvolini

and Giovanna Marrazza^*

Department of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 3, Sesto Fiorentino 50019, Italy

Sensors 2017, 17(4), 718; https://doi.org/10.3390/s17040718 - 29 Mar 2017

Cited by 162 | Viewed by 11704

Abstract

Detecting cancer disease at an early stage is one of the most important issues for increasing the survival rate of patients. Cancer biomarker detection helps to provide a diagnosis before the disease becomes incurable in later stages. Biomarkers can also be used to [...] Read more.

Detecting cancer disease at an early stage is one of the most important issues for increasing the survival rate of patients. Cancer biomarker detection helps to provide a diagnosis before the disease becomes incurable in later stages. Biomarkers can also be used to evaluate the progression of therapies and surgery treatments. In recent years, molecularly imprinted polymer (MIP) based sensors have been intensely investigated as promising analytical devices in several fields, including clinical analysis, offering desired portability, fast response, specificity, and low cost. The aim of this review is to provide readers with an overview on recent important achievements in MIP-based sensors coupled to various transducers (e.g., electrochemical, optical, and piezoelectric) for the determination of cancer biomarkers by selected publications from 2012 to 2016. Full article

(This article belongs to the Special Issue Biosensors for Cancer Biomarkers)

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11 pages, 3177 KiB

Open AccessReview

Low-Cost Inkjet Printing Technology for the Rapid Prototyping of Transducers

by Bruno Andò^1,*, Salvatore Baglio¹, Adi R. Bulsara², Teresa Emery², Vincenzo Marletta¹

and Antonio Pistorio¹

¹ DIEEI-University of Catania, v.le A. Doria, 6–95125 Catania, Italy

² Space and Naval Warfare Systems Center Pacific, Code 71000, San Diego, CA 92152-5000, USA

Sensors 2017, 17(4), 748; https://doi.org/10.3390/s17040748 - 1 Apr 2017

Cited by 73 | Viewed by 7925

Abstract

Recently, there has been an upsurge in efforts dedicated to developing low-cost flexible electronics by exploiting innovative materials and direct printing technologies. This interest is motivated by the need for low-cost mass-production, shapeable, and disposable devices, and the rapid prototyping of electronics and [...] Read more.

Recently, there has been an upsurge in efforts dedicated to developing low-cost flexible electronics by exploiting innovative materials and direct printing technologies. This interest is motivated by the need for low-cost mass-production, shapeable, and disposable devices, and the rapid prototyping of electronics and sensors. This review, following a short overview of main printing processes, reports examples of the development of flexible transducers through low-cost inkjet printing technology. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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24 pages, 11780 KiB

Open AccessReview

A Review of Rock Bolt Monitoring Using Smart Sensors

by Gangbing Song¹

, Weijie Li¹, Bo Wang^2,* and Siu Chun Michael Ho¹

¹ Department of Mechanical Engineering, University of Houston, Houston, TX 77004, USA

² Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China

Sensors 2017, 17(4), 776; https://doi.org/10.3390/s17040776 - 5 Apr 2017

Cited by 123 | Viewed by 22137

Abstract

Rock bolts have been widely used as rock reinforcing members in underground coal mine roadways and tunnels. Failures of rock bolts occur as a result of overloading, corrosion, seismic burst and bad grouting, leading to catastrophic economic and personnel losses. Monitoring the health [...] Read more.

Rock bolts have been widely used as rock reinforcing members in underground coal mine roadways and tunnels. Failures of rock bolts occur as a result of overloading, corrosion, seismic burst and bad grouting, leading to catastrophic economic and personnel losses. Monitoring the health condition of the rock bolts plays an important role in ensuring the safe operation of underground mines. This work presents a brief introduction on the types of rock bolts followed by a comprehensive review of rock bolt monitoring using smart sensors. Smart sensors that are used to assess rock bolt integrity are reviewed to provide a firm perception of the application of smart sensors for enhanced performance and reliability of rock bolts. The most widely used smart sensors for rock bolt monitoring are the piezoelectric sensors and the fiber optic sensors. The methodologies and principles of these smart sensors are reviewed from the point of view of rock bolt integrity monitoring. The applications of smart sensors in monitoring the critical status of rock bolts, such as the axial force, corrosion occurrence, grout quality and resin delamination, are highlighted. In addition, several prototypes or commercially available smart rock bolt devices are also introduced. Full article

(This article belongs to the Section Physical Sensors)

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36 pages, 7414 KiB

Open AccessReview

A Review of Wetland Remote Sensing

by Meng Guo^1,*

, Jing Li², Chunlei Sheng², Jiawei Xu¹ and Li Wu³

¹ School of Geographical Science, Northeast Normal University, Changchun 130024, China

² Northeast Institute of Geography and Agricultural Ecology, Chinese Academy of Science, Changchun 130102, China

³ Remote Sensing Technique Centre, Heilongjiang Academy of Agricultural Science, Harbin 150086, China

Sensors 2017, 17(4), 777; https://doi.org/10.3390/s17040777 - 5 Apr 2017

Cited by 385 | Viewed by 27896

Abstract

Wetlands are some of the most important ecosystems on Earth. They play a key role in alleviating floods and filtering polluted water and also provide habitats for many plants and animals. Wetlands also interact with climate change. Over the past 50 years, wetlands [...] Read more.

Wetlands are some of the most important ecosystems on Earth. They play a key role in alleviating floods and filtering polluted water and also provide habitats for many plants and animals. Wetlands also interact with climate change. Over the past 50 years, wetlands have been polluted and declined dramatically as land cover has changed in some regions. Remote sensing has been the most useful tool to acquire spatial and temporal information about wetlands. In this paper, seven types of sensors were reviewed: aerial photos coarse-resolution, medium-resolution, high-resolution, hyperspectral imagery, radar, and Light Detection and Ranging (LiDAR) data. This study also discusses the advantage of each sensor for wetland research. Wetland research themes reviewed in this paper include wetland classification, habitat or biodiversity, biomass estimation, plant leaf chemistry, water quality, mangrove forest, and sea level rise. This study also gives an overview of the methods used in wetland research such as supervised and unsupervised classification and decision tree and object-based classification. Finally, this paper provides some advice on future wetland remote sensing. To our knowledge, this paper is the most comprehensive and detailed review of wetland remote sensing and it will be a good reference for wetland researchers. Full article

(This article belongs to the Special Issue Understanding Land Surface Processes and Ecosystem Changes with Optical and Laser Remote Sensing)

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21 pages, 10748 KiB

Open AccessReview

Ground Penetrating Radar as a Contextual Sensor for Multi-Sensor Radiological Characterisation

by Ikechukwu K. Ukaegbu^*

and Kelum A. A. Gamage

Engineering Department, Lancaster University, Lancaster LA1 4YW, UK

Sensors 2017, 17(4), 790; https://doi.org/10.3390/s17040790 - 7 Apr 2017

Cited by 9 | Viewed by 7374

Abstract

Radioactive sources exist in environments or contexts that influence how they are detected and localised. For instance, the context of a moving source is different from a stationary source because of the effects of motion. The need to incorporate this contextual information in [...] Read more.

Radioactive sources exist in environments or contexts that influence how they are detected and localised. For instance, the context of a moving source is different from a stationary source because of the effects of motion. The need to incorporate this contextual information in the radiation detection and localisation process has necessitated the integration of radiological and contextual sensors. The benefits of the successful integration of both types of sensors is well known and widely reported in fields such as medical imaging. However, the integration of both types of sensors has also led to innovative solutions to challenges in characterising radioactive sources in non-medical applications. This paper presents a review of such recent applications. It also identifies that these applications mostly use visual sensors as contextual sensors for characterising radiation sources. However, visual sensors cannot retrieve contextual information about radioactive wastes located in opaque environments encountered at nuclear sites, e.g., underground contamination. Consequently, this paper also examines ground-penetrating radar (GPR) as a contextual sensor for characterising this category of wastes and proposes several ways of integrating data from GPR and radiological sensors. Finally, it demonstrates combined GPR and radiation imaging for three-dimensional localisation of contamination in underground pipes using radiation transport and GPR simulations. Full article

(This article belongs to the Section Remote Sensors)

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12 pages, 1850 KiB

Open AccessReview

The Development of Sensor Applications in the Sectors of Energy and Environment in Italy, 1976–2015

by Girolamo Di Francia

Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), P.le E. Fermi 1, Napoli 80055, Italy

Sensors 2017, 17(4), 793; https://doi.org/10.3390/s17040793 - 7 Apr 2017

Cited by 8 | Viewed by 5734

Abstract

Although sensor technologies have been developing quite similarly all over the world, the investigation of their applications has been more affected by the specific industrial and economic characteristics of each country. This paper aims to investigate the development of applications based on sensor [...] Read more.

Although sensor technologies have been developing quite similarly all over the world, the investigation of their applications has been more affected by the specific industrial and economic characteristics of each country. This paper aims to investigate the development of applications based on sensor devices in the sectors of energy and the environment, in Italy, throughout the last forty years (1976–2015), examining the most relevant papers published by Italian R & D groups working in this field. Italy depends on foreign imports for more than 80% of its primary energy needs, and this has directed the research effort on the development of sensor applications both to improve load shaping and consumers’ awareness and to develop specific equipment to maximize renewable energy production. Similarly, for the environment sector, there are increasing efforts to develop solutions to support a more and more capillary control of the environment itself using a cooperative approach. In both the sectors it seems that the solutions proposed can help to relieve the structural problems that Italy suffers and that the scientific and technical results obtained so far also have significant international relevance. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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63 pages, 21730 KiB

Open AccessReview

Recent Advances in Electrochemical Immunosensors

by Benoît Piro^* and Steeve Reisberg

University Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086 CNRS, 15 rue J-A de Baïf, 75205 Paris CEDEX 13, France

Sensors 2017, 17(4), 794; https://doi.org/10.3390/s17040794 - 7 Apr 2017

Cited by 80 | Viewed by 12704

Abstract

Immunosensors have experienced a very significant growth in recent years, driven by the need for fast, sensitive, portable and easy-to-use devices to detect biomarkers for clinical diagnosis or to monitor organic pollutants in natural or industrial environments. Advances in the field of signal [...] Read more.

Immunosensors have experienced a very significant growth in recent years, driven by the need for fast, sensitive, portable and easy-to-use devices to detect biomarkers for clinical diagnosis or to monitor organic pollutants in natural or industrial environments. Advances in the field of signal amplification using enzymatic reactions, nanomaterials such as carbon nanotubes, graphene and graphene derivatives, metallic nanoparticles (gold, silver, various oxides or metal complexes), or magnetic beads show how it is possible to improve collection, binding or transduction performances and reach the requirements for realistic clinical diagnostic or environmental control. This review presents these most recent advances; it focuses first on classical electrode substrates, then moves to carbon-based nanostructured ones including carbon nanotubes, graphene and other carbon materials, metal or metal-oxide nanoparticles, magnetic nanoparticles, dendrimers and, to finish, explore the use of ionic liquids. Analytical performances are systematically covered and compared, depending on the detection principle, but also from a chronological perspective, from 2012 to 2016 and early 2017. Full article

(This article belongs to the Special Issue Electrochemical Immunosensors)

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28 pages, 3072 KiB

Open AccessReview

SAW Sensors for Chemical Vapors and Gases

by Jagannath Devkota^1,2,*, Paul R. Ohodnicki^1,2,* and David W. Greve^1,3

¹ National Energy Technology Laboratory, Pittsburgh, PA 15236, USA

² Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA

³ Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA

Sensors 2017, 17(4), 801; https://doi.org/10.3390/s17040801 - 8 Apr 2017

Cited by 231 | Viewed by 21671

Abstract

Surface acoustic wave (SAW) technology provides a sensitive platform for sensing chemicals in gaseous and fluidic states with the inherent advantages of passive and wireless operation. In this review, we provide a general overview on the fundamental aspects and some major advances of [...] Read more.

Surface acoustic wave (SAW) technology provides a sensitive platform for sensing chemicals in gaseous and fluidic states with the inherent advantages of passive and wireless operation. In this review, we provide a general overview on the fundamental aspects and some major advances of Rayleigh wave-based SAW sensors in sensing chemicals in a gaseous phase. In particular, we review the progress in general understanding of the SAW chemical sensing mechanism, optimization of the sensor characteristics, and the development of the sensors operational at different conditions. Based on previous publications, we suggest some appropriate sensing approaches for particular applications and identify new opportunities and needs for additional research in this area moving into the future. Full article

(This article belongs to the Special Issue Acoustic Wave Resonator-Based Sensors)

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20 pages, 2427 KiB

Open AccessReview

Electrochemical Genosensing of Circulating Biomarkers

by Susana Campuzano^*

, Paloma Yáñez-Sedeño and José Manuel Pingarrón^*

Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain

Sensors 2017, 17(4), 866; https://doi.org/10.3390/s17040866 - 14 Apr 2017

Cited by 41 | Viewed by 8240

Abstract

Management and prognosis of diseases requires the measurement in non- or minimally invasively collected samples of specific circulating biomarkers, consisting of any measurable or observable factors in patients that indicate normal or disease-related biological processes or responses to therapy. Therefore, on-site, fast and [...] Read more.

Management and prognosis of diseases requires the measurement in non- or minimally invasively collected samples of specific circulating biomarkers, consisting of any measurable or observable factors in patients that indicate normal or disease-related biological processes or responses to therapy. Therefore, on-site, fast and accurate determination of these low abundance circulating biomarkers in scarcely treated body fluids is of great interest for health monitoring and biological applications. In this field, electrochemical DNA sensors (or genosensors) have demonstrated to be interesting alternatives to more complex conventional strategies. Currently, electrochemical genosensors are considered very promising analytical tools for this purpose due to their fast response, low cost, high sensitivity, compatibility with microfabrication technology and simple operation mode which makes them compatible with point-of-care (POC) testing. In this review, the relevance and current challenges of the determination of circulating biomarkers related to relevant diseases (cancer, bacterial and viral infections and neurodegenerative diseases) are briefly discussed. An overview of the electrochemical nucleic acid–based strategies developed in the last five years for this purpose is given to show to both familiar and non-expert readers the great potential of these methodologies for circulating biomarker determination. After highlighting the main features of the reported electrochemical genosensing strategies through the critical discussion of selected examples, a conclusions section points out the still existing challenges and future directions in this field. Full article

(This article belongs to the Special Issue Genosensing)

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22 pages, 833 KiB

Open AccessReview

Chemical Sensors and Biosensors in Italy: A Review of the 2015 Literature

by Dario Compagnone¹

, Girolamo Di Francia²

, Corrado Di Natale^3,*

, Giovanni Neri⁴

, Renato Seeber⁵ and Antonella Tajani⁶

¹ Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, 64100 Teramo, Italy

² ENEA Italian National Agency for New Technologies, Energy and Sustainable Economic Development, P.le E. Fermi 1, Napoli 80055, Italy

³ Department of Electronic Engineering, University of Rome Tor Vergata, 00133 Roma, Italy

⁴ Department of Engineering, University of Messina, 98166 Messina, Italy

⁵ Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy

⁶ Department of Physical Science and Technologies of Matter, National Research Council, 00133 Roma, Italy

Sensors 2017, 17(4), 868; https://doi.org/10.3390/s17040868 - 14 Apr 2017

Cited by 24 | Viewed by 6674

Abstract

The contributions of Italian researchers to sensor research in 2015 is reviewed. The analysis of the activities in one year allows one to obtain a snapshot of the Italian scenario capturing the main directions of the research activities. Furthermore, the distance of more [...] Read more.

The contributions of Italian researchers to sensor research in 2015 is reviewed. The analysis of the activities in one year allows one to obtain a snapshot of the Italian scenario capturing the main directions of the research activities. Furthermore, the distance of more than one year makes meaningful the bibliometric analysis of the reviewed papers. The review shows a research community distributed among different scientific disciplines, from chemistry, physics, engineering, and material science, with a strong interest in collaborative works. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technologies in Italy 2016)

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23 pages, 11114 KiB

Open AccessReview

Recent Developments in Fiber Optics Humidity Sensors

by Joaquin Ascorbe^1,*, Jesus M. Corres^1,2

, Francisco J. Arregui^1,2

and Ignacio R. Matias^1,2

¹ Department of Electrical and Electronic Engineering, Public University of Navarra, Pamplona 31006, Spain

² Institute of Smart Cities, Public University of Navarra, Pamplona 31006, Spain

Sensors 2017, 17(4), 893; https://doi.org/10.3390/s17040893 - 19 Apr 2017

Cited by 206 | Viewed by 13597

Abstract

A wide range of applications such as health, human comfort, agriculture, food processing and storage, and electronic manufacturing, among others, require fast and accurate measurement of humidity. Sensors based on optical fibers present several advantages over electronic sensors and great research efforts have [...] Read more.

A wide range of applications such as health, human comfort, agriculture, food processing and storage, and electronic manufacturing, among others, require fast and accurate measurement of humidity. Sensors based on optical fibers present several advantages over electronic sensors and great research efforts have been made in recent years in this field. The present paper reports the current trends of optical fiber humidity sensors. The evolution of optical structures developed towards humidity sensing, as well as the novel materials used for this purpose, will be analyzed. Well-known optical structures, such as long-period fiber gratings or fiber Bragg gratings, are still being studied towards an enhancement of their sensitivity. Sensors based on lossy mode resonances constitute a platform that combines high sensitivity with low complexity, both in terms of their fabrication process and the equipment required. Novel structures, such as resonators, are being studied in order to improve the resolution of humidity sensors. Moreover, recent research on polymer optical fibers suggests that the sensitivity of this kind of sensor has not yet reached its limit. Therefore, there is still room for improvement in terms of sensitivity and resolution. Full article

(This article belongs to the Special Issue Humidity Sensors)

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30 pages, 12848 KiB

Open AccessFeature PaperReview

Molecular Imprinting of Macromolecules for Sensor Applications

by Yeşeren Saylan¹

, Fatma Yilmaz², Erdoğan Özgür¹, Ali Derazshamshir¹, Handan Yavuz¹ and Adil Denizli^1,*

¹ Department of Chemistry, Division of Biochemistry, Hacettepe University, 06800 Ankara, Turkey

² Department of Chemistry Technology, Abant Izzet Baysal University, 14900 Bolu, Turkey

Sensors 2017, 17(4), 898; https://doi.org/10.3390/s17040898 - 19 Apr 2017

Cited by 156 | Viewed by 13252

Abstract

Molecular recognition has an important role in numerous living systems. One of the most important molecular recognition methods is molecular imprinting, which allows host compounds to recognize and detect several molecules rapidly, sensitively and selectively. Compared to natural systems, molecular imprinting methods have [...] Read more.

Molecular recognition has an important role in numerous living systems. One of the most important molecular recognition methods is molecular imprinting, which allows host compounds to recognize and detect several molecules rapidly, sensitively and selectively. Compared to natural systems, molecular imprinting methods have some important features such as low cost, robustness, high recognition ability and long term durability which allows molecularly imprinted polymers to be used in various biotechnological applications, such as chromatography, drug delivery, nanotechnology, and sensor technology. Sensors are important tools because of their ability to figure out a potentially large number of analytical difficulties in various areas with different macromolecular targets. Proteins, enzymes, nucleic acids, antibodies, viruses and cells are defined as macromolecules that have wide range of functions are very important. Thus, macromolecules detection has gained great attention in concerning the improvement in most of the studies. The applications of macromolecule imprinted sensors will have a spacious exploration according to the low cost, high specificity and stability. In this review, macromolecules for molecularly imprinted sensor applications are structured according to the definition of molecular imprinting methods, developments in macromolecular imprinting methods, macromolecular imprinted sensors, and conclusions and future perspectives. This chapter follows the latter strategies and focuses on the applications of macromolecular imprinted sensors. This allows discussion on how sensor strategy is brought to solve the macromolecules imprinting. Full article

(This article belongs to the Special Issue Biosensors and Molecular Imprinting)

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15 pages, 5466 KiB

Open AccessReview

Progress in the Correlative Atomic Force Microscopy and Optical Microscopy

by Lulu Zhou^1,2

, Mingjun Cai¹, Ti Tong^3,* and Hongda Wang^1,*

¹ State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China

² University of Chinese Academy of Sciences, Beijing 100049, China

³ The Second Hospital of Jilin University, Changchun 130041, China

Sensors 2017, 17(4), 938; https://doi.org/10.3390/s17040938 - 24 Apr 2017

Cited by 47 | Viewed by 11570

Abstract

Atomic force microscopy (AFM) has evolved from the originally morphological imaging technique to a powerful and multifunctional technique for manipulating and detecting the interactions between molecules at nanometer resolution. However, AFM cannot provide the precise information of synchronized molecular groups and has many [...] Read more.

Atomic force microscopy (AFM) has evolved from the originally morphological imaging technique to a powerful and multifunctional technique for manipulating and detecting the interactions between molecules at nanometer resolution. However, AFM cannot provide the precise information of synchronized molecular groups and has many shortcomings in the aspects of determining the mechanism of the interactions and the elaborate structure due to the limitations of the technology, itself, such as non-specificity and low imaging speed. To overcome the technical limitations, it is necessary to combine AFM with other complementary techniques, such as fluorescence microscopy. The combination of several complementary techniques in one instrument has increasingly become a vital approach to investigate the details of the interactions among molecules and molecular dynamics. In this review, we reported the principles of AFM and optical microscopy, such as confocal microscopy and single-molecule localization microscopy, and focused on the development and use of correlative AFM and optical microscopy. Full article

(This article belongs to the Special Issue Single-Molecule Sensing)

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1 pages, 127 KiB

Open AccessAddendum

Addendum: Larin, A.; Womble, P.C.; Dobrokhotov, V. Hybrid SnO₂/TiO₂ Nanocomposites for Selective Detection of Ultra-Low Hydrogen Sulfide Concentrations in Complex Backgrounds. Sensors 2016, 16, 1373.

by Alexander Larin^1,2, Phillip C. Womble¹ and Vladimir Dobrokhotov^3,*

¹ VAON LLC, KY, USA, 2200 Lapsley Lane, Bowling Green, KY 42103, USA

² Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292, USA

³ Applied Physics Institute, Western Kentucky University, Bowling Green, KY 42101, USA

Sensors 2017, 17(4), 768; https://doi.org/10.3390/s17040768 - 5 Apr 2017

Viewed by 2775

Abstract

The authors wish to make the following correction to their paper [1]:[...] Full article

(This article belongs to the Section Chemical Sensors)

12 pages, 2766 KiB

Open AccessTechnical Note

Development of a New, High Sensitivity 2000 kg Mechanical Balance

by Jian Wang

Division of Mechanics and Acoustics, National Institute of Metrology, Beijing 100029, China

Sensors 2017, 17(4), 851; https://doi.org/10.3390/s17040851 - 13 Apr 2017

Viewed by 3566

Abstract

Mass measurement of more than 500 kg on an electronic mass comparator has no better repeatability and linearity of measurement for meeting the calibration requirement of over class F1 weights from pharmacy and power generation plants. For this purpose, a new 2000 kg [...] Read more.

Mass measurement of more than 500 kg on an electronic mass comparator has no better repeatability and linearity of measurement for meeting the calibration requirement of over class F1 weights from pharmacy and power generation plants. For this purpose, a new 2000 kg mechanical balance was developed by the National Institute of Metrology (NIM). The advantages of measurement of more than 500 kg on a new 2000 kg mechanical balance are introduced in the paper. In order to obtain high measurement uncertainty, four vertical forces of two sides of beam are measured and used as reference for adjustment of the beam position. Laser displacement sensors in the indication system are more effective for decreasing reading errors caused by human vision. To improve the repeatability and sensitivity of the equipment, a synchronous lifting control is designed for synchronously lifting the beam ends along the vertical direction. A counterweight selection system is developed to get any combination of weights in a limited space. The sensitivity of the new mechanical balance for 2000 kg is more than 1.7 parts in 10⁻⁴ rad/g. The extended uncertainties for the mechanical balance of 500 kg, 1000 kg and 2000 kg are 0.47 g, 1.8 g and 3.5 g respectively. Full article

(This article belongs to the Special Issue Laser Sensors for Displacement, Distance, Flow, Velocity and Vibrations Measurements)

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