Sensors

30 pages, 1472 KiB

Open AccessArticle

An Effective Method for Substance Detection Using the Broad Spectrum THz Signal: A "Terahertz Nose"

by Vyacheslav A. Trofimov^* and Svetlana A. Varentsova

Faculty of Computational Mathematics and Cybernetics, Lomonosov Moscow State University, Leninskiye Gory, Moscow 119992, Russia;

Sensors 2015, 15(6), 12103-12132; https://doi.org/10.3390/s150612103 - 25 May 2015

Cited by 37 | Viewed by 6472

Abstract

We propose an effective method for the detection and identification of dangerous substances by using the broadband THz pulse. This pulse excites, for example, many vibrational or rotational energy levels of molecules simultaneously. By analyzing the time-dependent spectrum of the THz pulse transmitted [...] Read more.

We propose an effective method for the detection and identification of dangerous substances by using the broadband THz pulse. This pulse excites, for example, many vibrational or rotational energy levels of molecules simultaneously. By analyzing the time-dependent spectrum of the THz pulse transmitted through or reflected from a substance, we follow the average response spectrum dynamics. Comparing the absorption and emission spectrum dynamics of a substance under analysis with the corresponding data for a standard substance, one can detect and identify the substance under real conditions taking into account the influence of packing material, water vapor and substance surface. For quality assessment of the standard substance detection in the signal under analysis, we propose time-dependent integral correlation criteria. Restrictions of usually used detection and identification methods, based on a comparison between the absorption frequencies of a substance under analysis and a standard substance, are demonstrated using a physical experiment with paper napkins. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Graphical abstract

23 pages, 1548 KiB

Open AccessArticle

Assessing and Correcting Topographic Effects on Forest Canopy Height Retrieval Using Airborne LiDAR Data

by Zhugeng Duan^1,2,3, Dan Zhao¹, Yuan Zeng^1,*, Yujin Zhao¹, Bingfang Wu¹

and Jianjun Zhu²

¹ Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Science, Haidian District, Beijing 100094, China

² School of GeoSciences and Info-Physics, Central South University, Changsha 410083, China

³ School of Sciences, Central South University of Forestry and Technology, Changsha 410004, China

Sensors 2015, 15(6), 12133-12155; https://doi.org/10.3390/s150612133 - 26 May 2015

Cited by 30 | Viewed by 6808

Abstract

Topography affects forest canopy height retrieval based on airborne Light Detection and Ranging (LiDAR) data a lot. This paper proposes a method for correcting deviations caused by topography based on individual tree crown segmentation. The point cloud of an individual tree was extracted [...] Read more.

Topography affects forest canopy height retrieval based on airborne Light Detection and Ranging (LiDAR) data a lot. This paper proposes a method for correcting deviations caused by topography based on individual tree crown segmentation. The point cloud of an individual tree was extracted according to crown boundaries of isolated individual trees from digital orthophoto maps (DOMs). Normalized canopy height was calculated by subtracting the elevation of centres of gravity from the elevation of point cloud. First, individual tree crown boundaries are obtained by carrying out segmentation on the DOM. Second, point clouds of the individual trees are extracted based on the boundaries. Third, precise DEM is derived from the point cloud which is classified by a multi-scale curvature classification algorithm. Finally, a height weighted correction method is applied to correct the topological effects. The method is applied to LiDAR data acquired in South China, and its effectiveness is tested using 41 field survey plots. The results show that the terrain impacts the canopy height of individual trees in that the downslope side of the tree trunk is elevated and the upslope side is depressed. This further affects the extraction of the location and crown of individual trees. A strong correlation was detected between the slope gradient and the proportions of returns with height differences more than 0.3, 0.5 and 0.8 m in the total returns, with coefficient of determination R² of 0.83, 0.76, and 0.60 (n = 41), respectively. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

24 pages, 5649 KiB

Open AccessArticle

Self-Organizing Distributed Architecture Supporting Dynamic Space Expanding and Reducing in Indoor LBS Environment

by Seol Young Jeong, Hyeong Gon Jo and Soon Ju Kang^*

School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 702-701, Korea

Sensors 2015, 15(6), 12156-12179; https://doi.org/10.3390/s150612156 - 26 May 2015

Cited by 5 | Viewed by 6573

Abstract

Indoor location-based services (iLBS) are extremely dynamic and changeable, and include numerous resources and mobile devices. In particular, the network infrastructure requires support for high scalability in the indoor environment, and various resource lookups are requested concurrently and frequently from several locations based [...] Read more.

Indoor location-based services (iLBS) are extremely dynamic and changeable, and include numerous resources and mobile devices. In particular, the network infrastructure requires support for high scalability in the indoor environment, and various resource lookups are requested concurrently and frequently from several locations based on the dynamic network environment. A traditional map-based centralized approach for iLBSs has several disadvantages: it requires global knowledge to maintain a complete geographic indoor map; the central server is a single point of failure; it can also cause low scalability and traffic congestion; and it is hard to adapt to a change of service area in real time. This paper proposes a self-organizing and fully distributed platform for iLBSs. The proposed self-organizing distributed platform provides a dynamic reconfiguration of locality accuracy and service coverage by expanding and contracting dynamically. In order to verify the suggested platform, scalability performance according to the number of inserted or deleted nodes composing the dynamic infrastructure was evaluated through a simulation similar to the real environment. Full article

(This article belongs to the Special Issue Integrated Intelligent Sensory Systems with Self-x Capabilities)

▼ Show Figures

Graphical abstract

25 pages, 4970 KiB

Open AccessArticle

GNSS Space-Time Interference Mitigation and Attitude Determination in the Presence of Interference Signals

by Saeed Daneshmand^*, Ali Jafarnia Jahromi, Ali Broumandan and Gérard Lachapelle

PLAN Group, Department of Geomatics Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive, N.W., Calgary, AB T2N 1N4, Canada

Sensors 2015, 15(6), 12180-12204; https://doi.org/10.3390/s150612180 - 26 May 2015

Cited by 56 | Viewed by 6916

Abstract

The use of Space-Time Processing (STP) in Global Navigation Satellite System (GNSS) applications is gaining significant attention due to its effectiveness for both narrowband and wideband interference suppression. However, the resulting distortion and bias on the cross correlation functions due to space-time filtering [...] Read more.

The use of Space-Time Processing (STP) in Global Navigation Satellite System (GNSS) applications is gaining significant attention due to its effectiveness for both narrowband and wideband interference suppression. However, the resulting distortion and bias on the cross correlation functions due to space-time filtering is a major limitation of this technique. Employing the steering vector of the GNSS signals in the filter structure can significantly reduce the distortion on cross correlation functions and lead to more accurate pseudorange measurements. This paper proposes a two-stage interference mitigation approach in which the first stage estimates an interference-free subspace before the acquisition and tracking phases and projects all received signals into this subspace. The next stage estimates array attitude parameters based on detecting and employing GNSS signals that are less distorted due to the projection process. Attitude parameters enable the receiver to estimate the steering vector of each satellite signal and use it in the novel distortionless STP filter to significantly reduce distortion and maximize Signal-to-Noise Ratio (SNR). GPS signals were collected using a six-element antenna array under open sky conditions to first calibrate the antenna array. Simulated interfering signals were then added to the digitized samples in software to verify the applicability of the proposed receiver structure and assess its performance for several interference scenarios. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

13 pages, 1231 KiB

Open AccessArticle

Optimization and Application of Reflective LSPR Optical Fiber Biosensors Based on Silver Nanoparticles

by Jiangping Chen¹, Se Shi¹, Rongxin Su^1,2,*, Wei Qi^1,2,*, Renliang Huang³, Mengfan Wang¹, Libing Wang¹ and Zhimin He¹

¹ State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China

² Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China

³ School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China

Sensors 2015, 15(6), 12205-12217; https://doi.org/10.3390/s150612205 - 26 May 2015

Cited by 93 | Viewed by 11398

Abstract

In this study, we developed a reflective localized surface plasmon resonance (LSPR) optical fiber sensor, based on silver nanoparticles (Ag NPs). To enhance the sensitivity of the LSPR optical sensor, two key parameters were optimized, the length of the sensing area and the [...] Read more.

In this study, we developed a reflective localized surface plasmon resonance (LSPR) optical fiber sensor, based on silver nanoparticles (Ag NPs). To enhance the sensitivity of the LSPR optical sensor, two key parameters were optimized, the length of the sensing area and the coating time of the Ag NPs. A sensing length of 1.5 cm and a 1-h coating time proved to be suitable conditions to produce highly sensitive sensors for biosensing. The optimized sensor has a high refractive index sensitivity of 387 nm/RIU, which is much higher than that of other reported individual silver nanoparticles in solutions. Moreover, the sensor was further modified with antigen to act as a biosensor. Distinctive wavelength shifts were found after each surface modification step. In addition, the reflective LSPR optical fiber sensor has high reproducibility and stability. Full article

(This article belongs to the Special Issue Micro-Optical Sensors)

▼ Show Figures

Graphical abstract

24 pages, 4110 KiB

Open AccessArticle

Microfabrication and Integration of a Sol-Gel PZT Folded Spring Energy Harvester

by Jonathan Lueke¹, Ahmed Badr², Edmond Lou² and Walied A. Moussa^1,*

¹ Department of Mechanical Engineering, University of Alberta, University of Alberta, Edmonton, AB T6G 2G8, Canada

² Department of Electrical and Computer, University of Alberta, University of Alberta, Edmonton, AB T6G 2V4, Canada

Sensors 2015, 15(6), 12218-12241; https://doi.org/10.3390/s150612218 - 26 May 2015

Cited by 6 | Viewed by 10339

Abstract

This paper presents the methodology and challenges experienced in the microfabrication, packaging, and integration of a fixed-fixed folded spring piezoelectric energy harvester. A variety of challenges were overcome in the fabrication of the energy harvesters, such as the diagnosis and rectification of sol-gel [...] Read more.

This paper presents the methodology and challenges experienced in the microfabrication, packaging, and integration of a fixed-fixed folded spring piezoelectric energy harvester. A variety of challenges were overcome in the fabrication of the energy harvesters, such as the diagnosis and rectification of sol-gel PZT film quality and adhesion issues. A packaging and integration methodology was developed to allow for the characterizing the harvesters under a base vibration. The conditioning circuitry developed allowed for a complete energy harvesting system, consisting a harvester, a voltage doubler, a voltage regulator and a NiMH battery. A feasibility study was undertaken with the designed conditioning circuitry to determine the effect of the input parameters on the overall performance of the circuit. It was found that the maximum efficiency does not correlate to the maximum charging current supplied to the battery. The efficiency and charging current must be balanced to achieve a high output and a reasonable output current. The development of the complete energy harvesting system allows for the direct integration of the energy harvesting technology into existing power management schemes for wireless sensing. Full article

(This article belongs to the Special Issue Sol-Gel Based Sensors and Devices)

▼ Show Figures

Figure 1

18 pages, 1282 KiB

Open AccessArticle

A Low-Cost Sensing System for Cooperative Air Quality Monitoring in Urban Areas

by Simone Brienza^1,*, Andrea Galli¹, Giuseppe Anastasi¹ and Paolo Bruschi²

¹ Department of Information Engineering, University of Pisa, Largo Lucio Lazzarino 1, 56122 Pisa, Italy

² Department of Information Engineering, University of Pisa, Via G. Caruso 16, 56122 Pisa, Italy

Sensors 2015, 15(6), 12242-12259; https://doi.org/10.3390/s150612242 - 26 May 2015

Cited by 78 | Viewed by 11050

Abstract

Air quality in urban areas is a very important topic as it closely affects the health of citizens. Recent studies highlight that the exposure to polluted air can increase the incidence of diseases and deteriorate the quality of life. Hence, it is necessary [...] Read more.

Air quality in urban areas is a very important topic as it closely affects the health of citizens. Recent studies highlight that the exposure to polluted air can increase the incidence of diseases and deteriorate the quality of life. Hence, it is necessary to develop tools for real-time air quality monitoring, so as to allow appropriate and timely decisions. In this paper, we present uSense, a low-cost cooperative monitoring tool that allows knowing, in real-time, the concentrations of polluting gases in various areas of the city. Specifically, users monitor the areas of their interest by deploying low-cost and low-power sensor nodes. In addition, they can share the collected data following a social networking approach. uSense has been tested through an in-field experimentation performed in different areas of a city. The obtained results are in line with those provided by the local environmental control authority and show that uSense can be profitably used for air quality monitoring. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

▼ Show Figures

Figure 1

13 pages, 593 KiB

Open AccessArticle

Amorphous Silicon p-i-n Structure Acting as Light and Temperature Sensor

by Giampiero De Cesare^1,*,†, Augusto Nascetti^2,†

and Domenico Caputo^1,†

^† These authors contributed equally to this work.

¹ Department of Information Engineering, Electronics and Telecommunications, "La Sapienza" University of Rome, via Eudossiana 18, 00184 Rome, Italy

² Department of Astronautics, Electrical and Energetic Engineering, "La Sapienza" University of Rome, via Eudossiana 18, 00184 Rome, Italy

Sensors 2015, 15(6), 12260-12272; https://doi.org/10.3390/s150612260 - 26 May 2015

Cited by 36 | Viewed by 7039

Abstract

In this work, we propose a multi-parametric sensor able to measure both temperature and radiation intensity, suitable to increase the level of integration and miniaturization in Lab-on-Chip applications. The device is based on amorphous silicon p-doped/intrinsic/n-doped thin film junction. The device is first [...] Read more.

In this work, we propose a multi-parametric sensor able to measure both temperature and radiation intensity, suitable to increase the level of integration and miniaturization in Lab-on-Chip applications. The device is based on amorphous silicon p-doped/intrinsic/n-doped thin film junction. The device is first characterized as radiation and temperature sensor independently. We found a maximum value of responsivity equal to 350 mA/W at 510 nm and temperature sensitivity equal to 3.2 mV/K. We then investigated the effects of the temperature variation on light intensity measurement and of the light intensity variation on the accuracy of the temperature measurement. We found that the temperature variation induces an error lower than 0.55 pW/K in the light intensity measurement at 550 nm when the diode is biased in short circuit condition, while an error below 1 K/µW results in the temperature measurement when a forward bias current higher than 25 µA/cm² is applied. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

26 pages, 1085 KiB

Open AccessArticle

Random and Directed Walk-Based Top- Queries in Wireless Sensor Networks

by Jun-Song Fu and Yun Liu^*

School of Electronic and Information Engineering, Key Laboratory of Communication and Information Systems, Beijing Municipal Commission of Education, Beijing Jiaotong University, Beijing 100044, China

Sensors 2015, 15(6), 12273-12298; https://doi.org/10.3390/s150612273 - 26 May 2015

Cited by 3 | Viewed by 4075

Abstract

In wireless sensor networks, filter-based top- query approaches are the state-of-the-art solutions and have been extensively researched in the literature, however, they are very sensitive to the network parameters, including the size of the network, dynamics of the sensors’ readings and declines in [...] Read more.

In wireless sensor networks, filter-based top- query approaches are the state-of-the-art solutions and have been extensively researched in the literature, however, they are very sensitive to the network parameters, including the size of the network, dynamics of the sensors’ readings and declines in the overall range of all the readings. In this work, a random walk-based top- query approach called RWTQ and a directed walk-based top- query approach called DWTQ are proposed. At the beginning of a top- query, one or several tokens are sent to the specific node(s) in the network by the base station. Then, each token walks in the network independently to record and process the readings in a random or directed way. A strategy of choosing the “right” way in DWTQ is carefully designed for the token(s) to arrive at the high-value regions as soon as possible. When designing the walking strategy for DWTQ, the spatial correlations of the readings are also considered. Theoretical analysis and simulation results indicate that RWTQ and DWTQ both are very robust against these parameters discussed previously. In addition, DWTQ outperforms TAG, FILA and EXTOK in transmission cost, energy consumption and network lifetime. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

24 pages, 2203 KiB

Open AccessArticle

A Novel Software Architecture for the Provision of Context-Aware Semantic Transport Information

by Asier Moreno¹, Asier Perallos^1,*, Diego López-de-Ipiña¹

, Enrique Onieva¹

, Itziar Salaberria¹ and Antonio D. Masegosa^1,2

¹ Deusto Institute of Technology (DeustoTech), University of Deusto, Bilbao 48007, Spain

² IKERBASQUE, Basque Foundation for Science, Bilbao 48011, Spain

Sensors 2015, 15(6), 12299-12322; https://doi.org/10.3390/s150612299 - 26 May 2015

Cited by 5 | Viewed by 8199

Abstract

The effectiveness of Intelligent Transportation Systems depends largely on the ability to integrate information from diverse sources and the suitability of this information for the specific user. This paper describes a new approach for the management and exchange of this information, related to [...] Read more.

The effectiveness of Intelligent Transportation Systems depends largely on the ability to integrate information from diverse sources and the suitability of this information for the specific user. This paper describes a new approach for the management and exchange of this information, related to multimodal transportation. A novel software architecture is presented, with particular emphasis on the design of the data model and the enablement of services for information retrieval, thereby obtaining a semantic model for the representation of transport information. The publication of transport data as semantic information is established through the development of a Multimodal Transport Ontology (MTO) and the design of a distributed architecture allowing dynamic integration of transport data. The advantages afforded by the proposed system due to the use of Linked Open Data and a distributed architecture are stated, comparing it with other existing solutions. The adequacy of the information generated in regard to the specific user’s context is also addressed. Finally, a working solution of a semantic trip planner using actual transport data and running on the proposed architecture is presented, as a demonstration and validation of the system. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

▼ Show Figures

Figure 1

19 pages, 370 KiB

Open AccessArticle

Modeling Battery Behavior on Sensory Operations for Context-Aware Smartphone Sensing

by Ozgur Yurur¹, Chi Harold Liu^2,* and Wilfrido Moreno¹

¹ Department of Electrical Engineering, University of South Florida, Tampa, FL 33620, USA

² School of Software, Beijing Institute of Technology, Beijing 100081, China

Sensors 2015, 15(6), 12323-12341; https://doi.org/10.3390/s150612323 - 26 May 2015

Cited by 11 | Viewed by 4935

Abstract

Energy consumption is a major concern in context-aware smartphone sensing. This paper first studies mobile device-based battery modeling, which adopts the kinetic battery model (KiBaM), under the scope of battery non-linearities with respect to variant loads. Second, this paper models the energy consumption [...] Read more.

Energy consumption is a major concern in context-aware smartphone sensing. This paper first studies mobile device-based battery modeling, which adopts the kinetic battery model (KiBaM), under the scope of battery non-linearities with respect to variant loads. Second, this paper models the energy consumption behavior of accelerometers analytically and then provides extensive simulation results and a smartphone application to examine the proposed sensor model. Third, a Markov reward process is integrated to create energy consumption profiles, linking with sensory operations and their effects on battery non-linearity. Energy consumption profiles consist of different pairs of duty cycles and sampling frequencies during sensory operations. Furthermore, the total energy cost by each profile is represented by an accumulated reward in this process. Finally, three different methods are proposed on the evolution of the reward process, to present the linkage between different usage patterns on the accelerometer sensor through a smartphone application and the battery behavior. By doing this, this paper aims at achieving a fine efficiency in power consumption caused by sensory operations, while maintaining the accuracy of smartphone applications based on sensor usages. More importantly, this study intends that modeling the battery non-linearities together with investigating the effects of different usage patterns in sensory operations in terms of the power consumption and the battery discharge may lead to discovering optimal energy reduction strategies to extend the battery lifetime and help a continual improvement in context-aware mobile services. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

16 pages, 1361 KiB

Open AccessArticle

A New, Effective and Low-Cost Three-Dimensional Approach for the Estimation of Upper-Limb Volume

by Roberto Buffa¹, Elena Mereu¹, Paolo Lussu¹, Valeria Succa¹, Tonino Pisanu², Franco Buffa² and Elisabetta Marini^1,*

¹ Department of Life and Environmental Sciences, University of Cagliari, Cagliari 09126, Italy

² Metrology Group of Sardinia Radio Telescope, INAF, Selargius 09047, Italy

Sensors 2015, 15(6), 12342-12357; https://doi.org/10.3390/s150612342 - 26 May 2015

Cited by 29 | Viewed by 6090

Abstract

The aim of this research was to validate a new procedure (SkanLab) for the three-dimensional estimation of total arm volume. SkanLab is based on a single structured-light Kinect sensor (Microsoft, Redmond, WA, USA) and on Skanect (Occipital, San Francisco, CA, USA) and [...] Read more.

The aim of this research was to validate a new procedure (SkanLab) for the three-dimensional estimation of total arm volume. SkanLab is based on a single structured-light Kinect sensor (Microsoft, Redmond, WA, USA) and on Skanect (Occipital, San Francisco, CA, USA) and MeshLab (Visual Computing Lab, Pisa, Italy) software. The volume of twelve plastic cylinders was measured using geometry, as the reference, water displacement and SkanLab techniques (two raters and repetitions). The right total arm volume of thirty adults was measured by water displacement (reference) and SkanLab (two raters and repetitions). The bias and limits of agreement (LOA) between techniques were determined using the Bland–Altman method. Intra- and inter-rater reliability was assessed using the intraclass correlation coefficient (ICC) and the standard error of measurement. The bias of SkanLab in measuring the cylinders volume was −21.9 mL (−5.7%) (LOA: −62.0 to 18.2 mL; −18.1% to 6.7%) and in measuring the volume of arms’ was −9.9 mL (−0.6%) (LOA: −49.6 to 29.8 mL; −2.6% to 1.4%). SkanLab’s intra- and inter-rater reliabilities were very high (ICC >0.99). In conclusion, SkanLab is a fast, safe and low-cost method for assessing total arm volume, with high levels of accuracy and reliability. SkanLab represents a promising tool in clinical applications. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

19 pages, 1676 KiB

Open AccessArticle

An Energy-Efficient Underground Localization System Based on Heterogeneous Wireless Networks

by Yazhou Yuan¹, Cailian Chen^1,*, Xinping Guan^1,2 and Qiuling Yang²

¹ School of Electronic, Information and Electrical Engineering, Shanghai Jiaotong University, 800 Dongchuan RD. Minhang District, Shanghai 201100, China

² Institute of Electrical Engineering, Yanshan University, 438 Hebei Street Haigang District, Qinhuangdao 066000, China

Sensors 2015, 15(6), 12358-12376; https://doi.org/10.3390/s150612358 - 26 May 2015

Cited by 10 | Viewed by 5825

Abstract

A precision positioning system with energy efficiency is of great necessity for guaranteeing personnel safety in underground mines. The location information of the miners’ should be transmitted to the control center timely and reliably; therefore, a heterogeneous network with the backbone based on [...] Read more.

A precision positioning system with energy efficiency is of great necessity for guaranteeing personnel safety in underground mines. The location information of the miners’ should be transmitted to the control center timely and reliably; therefore, a heterogeneous network with the backbone based on high speed Industrial Ethernet is deployed. Since the mobile wireless nodes are working in an irregular tunnel, a specific wireless propagation model cannot fit all situations. In this paper, an underground localization system is designed to enable the adaptation to kinds of harsh tunnel environments, but also to reduce the energy consumption and thus prolong the lifetime of the network. Three key techniques are developed and implemented to improve the system performance, including a step counting algorithm with accelerometers, a power control algorithm and an adaptive packets scheduling scheme. The simulation study and experimental results show the effectiveness of the proposed algorithms and the implementation. Full article

(This article belongs to the Special Issue Towards Energy-Neutral WSN Architectures: Energy Harvesting and Other Enabling Technologies)

▼ Show Figures

12 pages, 5935 KiB

Open AccessArticle

Investigation of Two Novel Approaches for Detection of Sulfate Ion and Methane Dissolved in Sediment Pore Water Using Raman Spectroscopy

by Zengfeng Du¹, Jing Chen¹

, Wangquan Ye¹

, Jinjia Guo¹, Xin Zhang² and Ronger Zheng^1,*

¹ Optics and Optoelectronics Laboratory, Ocean University of China, Qingdao 266100, China

² Key Lab of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China

Sensors 2015, 15(6), 12377-12388; https://doi.org/10.3390/s150612377 - 26 May 2015

Cited by 17 | Viewed by 8932

Abstract

The levels of dissolved sulfate and methane are crucial indicators in the geochemical analysis of pore water. Compositional analysis of pore water samples obtained from sea trials was conducted using Raman spectroscopy. It was found that the concentration of SO₄²⁻ in [...] Read more.

The levels of dissolved sulfate and methane are crucial indicators in the geochemical analysis of pore water. Compositional analysis of pore water samples obtained from sea trials was conducted using Raman spectroscopy. It was found that the concentration of SO₄²⁻ in pore water samples decreases as the depth increases, while the expected Raman signal of methane has not been observed. A possible reason for this is that the methane escaped after sampling and the remaining concentration of methane is too low to be detected. To find more effective ways to analyze the composition of pore water, two novel approaches are proposed. One is based on Liquid Core Optical Fiber (LCOF) for detection of SO₄²⁻. The other one is an enrichment process for the detection of CH₄. With the aid of LCOF, the Raman signal of SO₄²⁻ is found to be enhanced over 10 times compared to that obtained by a conventional Raman setup. The enrichment process is also found to be effective in the investigation to the prepared sample of methane dissolved in water. By CCl₄ extraction, methane at a concentration below 1.14 mmol/L has been detected by conventional Raman spectroscopy. All the obtained results suggest that the approach proposed in this paper has great potential to be developed as a sensor for SO₄²⁻ and CH₄ detection in pore water. Full article

(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)

▼ Show Figures

Figure 1

21 pages, 1961 KiB

Open AccessArticle

Reducing Systematic Centroid Errors Induced by Fiber Optic Faceplates in Intensified High-Accuracy Star Trackers

by Kun Xiong^† and Jie Jiang^*,†

¹ Key Laboratory of Precision Opto-Mechatronics Technology, Ministry of Education, School of Instrumentation Science and Opto-Electronics Engineering, Beijing University of Aeronautics and Astronautics (BUAA), Beijing 100191, China

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 12389-12409; https://doi.org/10.3390/s150612389 - 26 May 2015

Cited by 6 | Viewed by 6246

Abstract

Compared with traditional star trackers, intensified high-accuracy star trackers equipped with an image intensifier exhibit overwhelmingly superior dynamic performance. However, the multiple-fiber-optic faceplate structure in the image intensifier complicates the optoelectronic detecting system of star trackers and may cause considerable systematic centroid errors [...] Read more.

Compared with traditional star trackers, intensified high-accuracy star trackers equipped with an image intensifier exhibit overwhelmingly superior dynamic performance. However, the multiple-fiber-optic faceplate structure in the image intensifier complicates the optoelectronic detecting system of star trackers and may cause considerable systematic centroid errors and poor attitude accuracy. All the sources of systematic centroid errors related to fiber optic faceplates (FOFPs) throughout the detection process of the optoelectronic system were analyzed. Based on the general expression of the systematic centroid error deduced in the frequency domain and the FOFP modulation transfer function, an accurate expression that described the systematic centroid error of FOFPs was obtained. Furthermore, reduction of the systematic error between the optical lens and the input FOFP of the intensifier, the one among multiple FOFPs and the one between the output FOFP of the intensifier and the imaging chip of the detecting system were discussed. Two important parametric constraints were acquired from the analysis. The correctness of the analysis on the optoelectronic detecting system was demonstrated through simulation and experiment. Full article

(This article belongs to the Special Issue Sensor Innovations for Spacecraft Guidance, Navigation, and Control)

▼ Show Figures

Figure 1

18 pages, 3083 KiB

Open AccessArticle

Real-Time Human Pose Estimation and Gesture Recognition from Depth Images Using Superpixels and SVM Classifier

by Hanguen Kim¹, Sangwon Lee¹, Dongsung Lee², Soonmin Choi², Jinsun Ju² and Hyun Myung^1,*

¹ Urban Robotics Laboratory (URL), Dept. Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-338, Korea

² Image & Video Research Group, Samsung S1 Cooperation, 168 S1 Building, Soonhwa-dong,Joong-gu, Seoul 100-773, Korea

Sensors 2015, 15(6), 12410-12427; https://doi.org/10.3390/s150612410 - 26 May 2015

Cited by 35 | Viewed by 9215

Abstract

In this paper, we present human pose estimation and gesture recognition algorithms that use only depth information. The proposed methods are designed to be operated with only a CPU (central processing unit), so that the algorithm can be operated on a low-cost platform, [...] Read more.

In this paper, we present human pose estimation and gesture recognition algorithms that use only depth information. The proposed methods are designed to be operated with only a CPU (central processing unit), so that the algorithm can be operated on a low-cost platform, such as an embedded board. The human pose estimation method is based on an SVM (support vector machine) and superpixels without prior knowledge of a human body model. In the gesture recognition method, gestures are recognized from the pose information of a human body. To recognize gestures regardless of motion speed, the proposed method utilizes the keyframe extraction method. Gesture recognition is performed by comparing input keyframes with keyframes in registered gestures. The gesture yielding the smallest comparison error is chosen as a recognized gesture. To prevent recognition of gestures when a person performs a gesture that is not registered, we derive the maximum allowable comparison errors by comparing each registered gesture with the other gestures. We evaluated our method using a dataset that we generated. The experiment results show that our method performs fairly well and is applicable in real environments. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

26 pages, 4462 KiB

Open AccessArticle

Development of a Portable Non-Invasive Swallowing and Respiration Assessment Device

by Wann-Yun Shieh^1,*,‡, Chin-Man Wang^2,3,‡ and Chia-Shuo Chang¹

¹ Department of Computer Science and Information Engineering, Chang Gung University, No. 259, Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan

² Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Taoyuan 333, Taiwan

³ Department of Medicine, Chang Gung University, No. 5, Fu-Hsing Street, Kwei Shan, Tao-Yuan 333, Taiwan

Sensors 2015, 15(6), 12428-12453; https://doi.org/10.3390/s150612428 - 27 May 2015

Cited by 35 | Viewed by 8770

Abstract

Dysphagia is a condition that happens when a person cannot smoothly swallow food from the mouth to the stomach. It causes malnourishment in patients, or can even cause death due to aspiration pneumonia. Recently, more and more researchers have focused their attention on [...] Read more.

Dysphagia is a condition that happens when a person cannot smoothly swallow food from the mouth to the stomach. It causes malnourishment in patients, or can even cause death due to aspiration pneumonia. Recently, more and more researchers have focused their attention on the importance of swallowing and respiration coordination, and the use of non-invasive assessment systems has become a hot research trend. In this study, we aimed to integrate the timing and pattern monitoring of respiration and swallowing by using a portable and non-invasive approach which can be applied at the bedside in hospitals or institutions, or in a home environment. In this approach, we use a force sensing resistor (FSR) to detect the motions of the thyroid cartilage in the pharyngeal phase. We also use the surface electromyography (sEMG) to detect the contraction of the submental muscle in the oral phase, and a nasal cannula to detect nasal airflow for respiration monitoring during the swallowing process. All signals are received and processed for swallowing event recognition. A total of 19 volunteers participated in the testing and over 57 measurements were made. The results show that the proposed approach can effectively distinguish the swallowing function in people of different ages and genders. Full article

(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering)

▼ Show Figures

Figure 1

20 pages, 9679 KiB

Open AccessArticle

Aperiodic Linear Networked Control Considering Variable Channel Delays: Application to Robots Coordination

by Carlos Santos^1,*, Felipe Espinosa¹, Enrique Santiso¹ and Manuel Mazo, Jr.²

¹ Electronics Department, Polytechnics School, University of Alcala, Campus Universitario, Ctra. Madrid-Barcelona, Km. 33,600, 28871. Alcalá de Henares, Madrid, Spain

² Delft Center of Systems and Control, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands

Sensors 2015, 15(6), 12454-12473; https://doi.org/10.3390/s150612454 - 27 May 2015

Cited by 11 | Viewed by 5537

Abstract

One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance. In this way, communication resources are liberated for other applications sharing the channel bandwidth. The main contribution of this work [...] Read more.

One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance. In this way, communication resources are liberated for other applications sharing the channel bandwidth. The main contribution of this work is the design of a remote control solution based on an aperiodic and adaptive triggering mechanism considering the current network delay of multiple robotics units. Working with the actual network delay instead of the maximum one leads to abandoning this conservative assumption, since the triggering condition is fixed depending on the current state of the network. This way, the controller manages the usage of the wireless channel in order to reduce the channel delay and to improve the availability of the communication resources. The communication standard under study is the widespread IEEE 802.11g, whose channel delay is clearly uncertain. First, the adaptive self-triggered control is validated through the TrueTime simulation tool configured for the mentioned WiFi standard. Implementation results applying the aperiodic linear control laws on four P3-DX robots are also included. Both of them demonstrate the advantage of this solution in terms of network accessing and control performance with respect to periodic and non-adaptive self-triggered alternatives. Full article

(This article belongs to the Special Issue Cyber-Physical Systems)

▼ Show Figures

24 pages, 617 KiB

Open AccessArticle

Ultrasonic Sensor Signals and Optimum Path Forest Classifier for the Microstructural Characterization of Thermally-Aged Inconel 625 Alloy

by Victor Hugo C. De Albuquerque^1,*

, Cleisson V. Barbosa¹, Cleiton C. Silva², Elineudo P. Moura², Pedro P. Rebouças Filho³

, João P. Papa⁴ and João Manuel R. S. Tavares⁵

¹ Programa de Pós-Graduação em Informática Aplicada, Universidade de Fortaleza, Fortaleza, Ceará 60811-905, Brazil

² Departamento de Engenharia Metalúrgica e de Materiais, Universidade Federal do Ceará, Fortaleza, Ceará 60455-900, Brazil

³ Programa de Pós-Graduação em Ciências da Computação, Instituto Federal de Educação, Ciência e Tecnologia do Ceará, Fortaleza, Ceará 61939-140, Brazil

⁴ Departamento de Ciência da Computação, Universidade Estadual Paulista, Bauru, São Paulo 17033-360, Brazil

⁵ Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial, Departamento de Engenharia Mecânica, Faculdade de Engenharia, Universidade do Porto, Porto 4200-465, Portugal

Sensors 2015, 15(6), 12474-12497; https://doi.org/10.3390/s150612474 - 27 May 2015

Cited by 20 | Viewed by 5649

Abstract

Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the [...] Read more.

Secondary phases, such as laves and carbides, are formed during the final solidification stages of nickel-based superalloy coatings deposited during the gas tungsten arc welding cold wire process. However, when aged at high temperatures, other phases can precipitate in the microstructure, like the γ'' and δ phases. This work presents an evaluation of the powerful optimum path forest (OPF) classifier configured with six distance functions to classify background echo and backscattered ultrasonic signals from samples of the inconel 625 superalloy thermally aged at 650 and 950 (^circ)C for 10, 100 and 200 h. The background echo and backscattered ultrasonic signals were acquired using transducers with frequencies of 4 and 5 MHz. The potentiality of ultrasonic sensor signals combined with the OPF to characterize the microstructures of an inconel 625 thermally aged and in the as-welded condition were confirmed by the results. The experimental results revealed that the OPF classifier is sufficiently fast (classification total time of 0.316 ms) and accurate (accuracy of 88.75% and harmonic mean of 89.52) for the application proposed. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

15 pages, 2666 KiB

Open AccessArticle

Impedance of the Grape Berry Cuticle as a Novel Phenotypic Trait to Estimate Resistance to Botrytis Cinerea

by Katja Herzog^*, Rolf Wind and Reinhard Töpfer

Julius Kühn-Institut-Federal Research Centre of Cultivated Plants, Institute for Grapevine Breeding Geilweilerhof, Siebeldingen 76833, Germany

Sensors 2015, 15(6), 12498-12512; https://doi.org/10.3390/s150612498 - 27 May 2015

Cited by 48 | Viewed by 11077

Abstract

Warm and moist weather conditions during berry ripening provoke Botrytis cinerea (B. cinerea) causing notable bunch rot on susceptible grapevines with the effect of reduced yield and wine quality. Resistance donors of genetic loci to increase B. cinerea resistance are widely [...] Read more.

Warm and moist weather conditions during berry ripening provoke Botrytis cinerea (B. cinerea) causing notable bunch rot on susceptible grapevines with the effect of reduced yield and wine quality. Resistance donors of genetic loci to increase B. cinerea resistance are widely unknown. Promising traits of resistance are represented by physical features like the thickness and permeability of the grape berry cuticle. Sensor-based phenotyping methods or genetic markers are rare for such traits. In the present study, the simple-to-handle I-sensor was developed. The sensor enables the fast and reliable measurement of electrical impedance of the grape berry cuticles and its epicuticular waxes (CW). Statistical experiments revealed highly significant correlations between relative impedance of CW and the resistance of grapevines to B. cinerea. Thus, the relative impedance Z_rel of CW was identified as the most important phenotypic factor with regard to the prediction of grapevine resistance to B. cinerea. An ordinal logistic regression analysis revealed a R²_McFadden of 0.37 and confirmed the application of Z_rel of CW for the prediction of bunch infection and in this way as novel phenotyping trait. Applying the I-sensor, a preliminary QTL region was identified indicating that the novel phenotypic trait is as well a valuable tool for genetic analyses. Full article

(This article belongs to the Collection Sensors in Agriculture and Forestry)

▼ Show Figures

Figure 1

13 pages, 1678 KiB

Open AccessArticle

Optical Detection of Paraoxon Using Single-Walled Carbon Nanotube Films with Attached Organophosphorus Hydrolase-Expressed Escherichia coli

by Intae Kim¹, Geon Hwee Kim¹, Chang Sup Kim², Hyung Joon Cha³ and Geunbae Lim^1,*

¹ Department of Mechanical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 790-784, Korea

² School of Biotechnology and Graduate School of Biochemistry, Yeungnam Univerisity, 280 Daehak-Ro, Gyeongsan, Gyeongbuk 712-749, Korea

³ Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 790-784, Korea

Sensors 2015, 15(6), 12513-12525; https://doi.org/10.3390/s150612513 - 27 May 2015

Cited by 17 | Viewed by 7561

Abstract

In whole-cell based biosensors, spectrophotometry is one of the most commonly used methods for detecting organophosphates due to its simplicity and reliability. The sensor performance is directly affected by the cell immobilization method because it determines the amount of cells, the mass transfer [...] Read more.

In whole-cell based biosensors, spectrophotometry is one of the most commonly used methods for detecting organophosphates due to its simplicity and reliability. The sensor performance is directly affected by the cell immobilization method because it determines the amount of cells, the mass transfer rate, and the stability. In this study, we demonstrated that our previously-reported microbe immobilization method, a microbe-attached single-walled carbon nanotube film, can be applied to whole-cell-based organophosphate sensors. This method has many advantages over other whole-cell organophosphate sensors, including high specific activity, quick cell immobilization, and excellent stability. A device with circular electrodes was fabricated for an enlarged cell-immobilization area. Escherichia coli expressing organophosphorus hydrolase in the periplasmic space and single-walled carbon nanotubes were attached to the device by our method. Paraoxon was hydrolyzed using this device, and detected by measuring the concentration of the enzymatic reaction product, p-nitrophenol. The specific activity of our device was calculated, and was shown to be over 2.5 times that reported previously for other whole-cell organophosphate sensors. Thus, this method for generation of whole-cell-based OP biosensors might be optimal, as it overcomes many of the caveats that prevent the widespread use of other such devices. Full article

(This article belongs to the Special Issue Optical Sensors for Chemical, Biological and Industrial Applications)

▼ Show Figures

Graphical abstract

13 pages, 654 KiB

Open AccessArticle

Strong Ferromagnetically-Coupled Spin Valve Sensor Devices for Droplet Magnetofluidics

by Gungun Lin^1,2,*, Denys Makarov¹ and Oliver G. Schmidt^1,2

¹ Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany

² Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainerstr. 70, 09107 Chemnitz, Germany

Sensors 2015, 15(6), 12526-12538; https://doi.org/10.3390/s150612526 - 27 May 2015

Cited by 9 | Viewed by 8526

Abstract

We report a magnetofluidic device with integrated strong ferromagnetically-coupled and hysteresis-free spin valve sensors for dynamic monitoring of ferrofluid droplets in microfluidics. The strong ferromagnetic coupling between the free layer and the pinned layer of spin valve sensors is achieved by reducing the [...] Read more.

We report a magnetofluidic device with integrated strong ferromagnetically-coupled and hysteresis-free spin valve sensors for dynamic monitoring of ferrofluid droplets in microfluidics. The strong ferromagnetic coupling between the free layer and the pinned layer of spin valve sensors is achieved by reducing the spacer thickness, while the hysteresis of the free layer is eliminated by the interplay between shape anisotropy and the strength of coupling. The increased ferromagnetic coupling field up to the remarkable 70 Oe, which is five-times larger than conventional solutions, brings key advantages for dynamic sensing, e.g., a larger biasing field giving rise to larger detection signals, facilitating the operation of devices without saturation of the sensors. Studies on the fundamental effects of an external magnetic field on the evolution of the shape of droplets, as enabled by the non-visual monitoring capability of the device, provides crucial information for future development of a magnetofluidic device for multiplexed assays. Full article

(This article belongs to the Special Issue Magnetic Sensor Device-Part 1)

▼ Show Figures

Graphical abstract

21 pages, 1964 KiB

Open AccessArticle

Target Localization in Wireless Sensor Networks Using Online Semi-Supervised Support Vector Regression

by Jaehyun Yoo and H. Jin Kim^*

Department of Mechanical and Aerospace Engineering, Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul KS013, Korea

Sensors 2015, 15(6), 12539-12559; https://doi.org/10.3390/s150612539 - 27 May 2015

Cited by 46 | Viewed by 5948

Abstract

Machine learning has been successfully used for target localization in wireless sensor networks (WSNs) due to its accurate and robust estimation against highly nonlinear and noisy sensor measurement. For efficient and adaptive learning, this paper introduces online semi-supervised support vector regression (OSS-SVR). The [...] Read more.

Machine learning has been successfully used for target localization in wireless sensor networks (WSNs) due to its accurate and robust estimation against highly nonlinear and noisy sensor measurement. For efficient and adaptive learning, this paper introduces online semi-supervised support vector regression (OSS-SVR). The first advantage of the proposed algorithm is that, based on semi-supervised learning framework, it can reduce the requirement on the amount of the labeled training data, maintaining accurate estimation. Second, with an extension to online learning, the proposed OSS-SVR automatically tracks changes of the system to be learned, such as varied noise characteristics. We compare the proposed algorithm with semi-supervised manifold learning, an online Gaussian process and online semi-supervised colocalization. The algorithms are evaluated for estimating the unknown location of a mobile robot in a WSN. The experimental results show that the proposed algorithm is more accurate under the smaller amount of labeled training data and is robust to varying noise. Moreover, the suggested algorithm performs fast computation, maintaining the best localization performance in comparison with the other methods. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

13 pages, 2045 KiB

Open AccessArticle

Characterization of Wheat Varieties Using Terahertz Time-Domain Spectroscopy

by Hongyi Ge^1,2,*, Yuying Jiang^1,2, Feiyu Lian³, Yuan Zhang³ and Shanhong Xia^1,2

¹ State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100080, China

² University of the Chinese Academy of Sciences, Beijing 100080, China

³ Key Laboratory of Grain Information Processing & Control, Ministry of Education, Zhengzhou 450001, China

Sensors 2015, 15(6), 12560-12572; https://doi.org/10.3390/s150612560 - 27 May 2015

Cited by 38 | Viewed by 7581

Abstract

Terahertz (THz) spectroscopy and multivariate data analysis were explored to discriminate eight wheat varieties. The absorption spectra were measured using THz time-domain spectroscopy from 0.2 to 2.0 THz. Using partial least squares (PLS), a regression model for discriminating wheat varieties was developed. The [...] Read more.

Terahertz (THz) spectroscopy and multivariate data analysis were explored to discriminate eight wheat varieties. The absorption spectra were measured using THz time-domain spectroscopy from 0.2 to 2.0 THz. Using partial least squares (PLS), a regression model for discriminating wheat varieties was developed. The coefficient of correlation in cross validation (R) and root-mean-square error of cross validation (RMSECV) were 0.985 and 1.162, respectively. In addition, interval PLS was applied to optimize the models by selecting the most appropriate regions in the spectra, improving the prediction accuracy (R = 0.992 and RMSECV = 0.967). Results demonstrate that THz spectroscopy combined with multivariate analysis can provide rapid, nondestructive discrimination of wheat varieties. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

Graphical abstract

21 pages, 2136 KiB

Open AccessReview

Diamond Nanowires: A Novel Platform for Electrochemistry and Matrix-Free Mass Spectrometry

by Sabine Szunerits^*, Yannick Coffinier and Rabah Boukherroub

Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR-CNRS 8520, Université Lille 1, Avenue Poincaré—BP 60069, 59655 Villeneuve d'Ascq, France

Sensors 2015, 15(6), 12573-12593; https://doi.org/10.3390/s150612573 - 27 May 2015

Cited by 42 | Viewed by 9120

Abstract

Over the last decades, carbon-based nanostructures have generated a huge interest from both fundamental and technological viewpoints owing to their physicochemical characteristics, markedly different from their corresponding bulk states. Among these nanostructured materials, carbon nanotubes (CNTs), and more recently graphene and its derivatives, [...] Read more.

Over the last decades, carbon-based nanostructures have generated a huge interest from both fundamental and technological viewpoints owing to their physicochemical characteristics, markedly different from their corresponding bulk states. Among these nanostructured materials, carbon nanotubes (CNTs), and more recently graphene and its derivatives, hold a central position. The large amount of work devoted to these materials is driven not only by their unique mechanical and electrical properties, but also by the advances made in synthetic methods to produce these materials in large quantities with reasonably controllable morphologies. While much less studied than CNTs and graphene, diamond nanowires, the diamond analogue of CNTs, hold promise for several important applications. Diamond nanowires display several advantages such as chemical inertness, high mechanical strength, high thermal and electrical conductivity, together with proven biocompatibility and existence of various strategies to functionalize their surface. The unique physicochemical properties of diamond nanowires have generated wide interest for their use as fillers in nanocomposites, as light detectors and emitters, as substrates for nanoelectronic devices, as tips for scanning probe microscopy as well as for sensing applications. In the past few years, studies on boron-doped diamond nanowires (BDD NWs) focused on increasing their electrochemical active surface area to achieve higher sensitivity and selectivity compared to planar diamond interfaces. The first part of the present review article will cover the promising applications of BDD NWS for label-free sensing. Then, the potential use of diamond nanowires as inorganic substrates for matrix-free laser desorption/ionization mass spectrometry, a powerful label-free approach for quantification and identification of small compounds, will be discussed. Full article

(This article belongs to the Special Issue Label-Free Sensing)

▼ Show Figures

Figure 1

19 pages, 3508 KiB

Open AccessArticle

Peculiarities of the Third Natural Frequency Vibrations of a Cantilever for the Improvement of Energy Harvesting

by Vytautas Ostasevicius¹, Giedrius Janusas^2,*

, Ieva Milasauskaite¹, Mindaugas Zilys³ and Laura Kizauskiene⁴

¹ Institute of Mechatronics, Kaunas University of Technology, Studentu 56-123, Kaunas LT-51368, Lithuania

² Faculty of Mechanical Engineering and Design, Kaunas University of Technology, Studentu 56-338, Kaunas LT-51368, Lithuania

³ Faculty of Electrical and Electronics Engineering, Kaunas University of Technology, Studentu 48-211, Kaunas LT-51368, Lithuania

⁴ Faculty of Informatics, Kaunas University of Technology, Studentu 48-213, Kaunas LT-51368, Lithuania

Sensors 2015, 15(6), 12594-12612; https://doi.org/10.3390/s150612594 - 28 May 2015

Cited by 13 | Viewed by 6394

Abstract

This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. [...] Read more.

This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH) prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4–4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Graphical abstract

22 pages, 6005 KiB

Open AccessArticle

Design and Implementation of an Intrinsically Safe Liquid-Level Sensor Using Coaxial Cable

by Baoquan Jin^*, Xin Liu, Qing Bai, Dong Wang and Yu Wang

Key Laboratory of Advanced Transducers and Intelligent Control Systems, Ministry of Education, Taiyuan University of Technology, No.79 Yingzexi Street, Taiyuan 030024, China

Sensors 2015, 15(6), 12613-12634; https://doi.org/10.3390/s150612613 - 28 May 2015

Cited by 33 | Viewed by 14071

Abstract

Real-time detection of liquid level in complex environments has always been a knotty issue. In this paper, an intrinsically safe liquid-level sensor system for flammable and explosive environments is designed and implemented. The poly vinyl chloride (PVC) coaxial cable is chosen as the [...] Read more.

Real-time detection of liquid level in complex environments has always been a knotty issue. In this paper, an intrinsically safe liquid-level sensor system for flammable and explosive environments is designed and implemented. The poly vinyl chloride (PVC) coaxial cable is chosen as the sensing element and the measuring mechanism is analyzed. Then, the capacitance-to-voltage conversion circuit is designed and the expected output signal is achieved by adopting parameter optimization. Furthermore, the experimental platform of the liquid-level sensor system is constructed, which involves the entire process of measuring, converting, filtering, processing, visualizing and communicating. Additionally, the system is designed with characteristics of intrinsic safety by limiting the energy of the circuit to avoid or restrain the thermal effects and sparks. Finally, the approach of the piecewise linearization is adopted in order to improve the measuring accuracy by matching the appropriate calibration points. The test results demonstrate that over the measurement range of 1.0 m, the maximum nonlinearity error is 0.8% full-scale span (FSS), the maximum repeatability error is 0.5% FSS, and the maximum hysteresis error is reduced from 0.7% FSS to 0.5% FSS by applying software compensation algorithms. Full article

(This article belongs to the Special Issue Sensors for Harsh Environments)

▼ Show Figures

Figure 1

16 pages, 541 KiB

Open AccessArticle

Cooperative Energy Harvesting-Adaptive MAC Protocol for WBANs

by Volker Esteves¹, Angelos Antonopoulos², Elli Kartsakli^2,*, Manel Puig-Vidal¹

, Pere Miribel-Català¹ and Christos Verikoukis¹

¹ Department of Electronics, University of Barcelona (UB), Barcelona 08028, Spain

² Department of Signal Theory and Communications (TSC), Technical University of Catalonia (UPC—BarcelonaTECH), C./ Esteve Terradas 7, C4-202P, Castelldefels 08860, Spain

Sensors 2015, 15(6), 12635-12650; https://doi.org/10.3390/s150612635 - 28 May 2015

Cited by 61 | Viewed by 7171

Abstract

In this paper, we introduce a cooperative medium access control (MAC) protocol, named cooperative energy harvesting (CEH)-MAC, that adapts its operation to the energy harvesting (EH) conditions in wireless body area networks (WBANs). In particular, the proposed protocol exploits the EH information in [...] Read more.

In this paper, we introduce a cooperative medium access control (MAC) protocol, named cooperative energy harvesting (CEH)-MAC, that adapts its operation to the energy harvesting (EH) conditions in wireless body area networks (WBANs). In particular, the proposed protocol exploits the EH information in order to set an idle time that allows the relay nodes to charge their batteries and complete the cooperation phase successfully. Extensive simulations have shown that CEH-MAC significantly improves the network performance in terms of throughput, delay and energy efficiency compared to the cooperative operation of the baseline IEEE 802.15.6 standard. Full article

(This article belongs to the Special Issue Towards Energy-Neutral WSN Architectures: Energy Harvesting and Other Enabling Technologies)

▼ Show Figures

17 pages, 862 KiB

Open AccessArticle

Low-Cost Impact Detection and Location for Automated Inspections of 3D Metallic Based Structures

by Carlos Morón¹

, Marina P. Portilla², José A. Somolinos² and Rafael Morales^3,*

¹ Sensors and Actuators Group, Universidad Politécnica de Madrid, Juan de Herrera 6, Madrid 28040, Spain

² GITERM. ETS I. Navales, Universidad Politécnica de Madrid, Arco de la Victoria 4, Madrid 28040, Spain

³ E.T.S.I. Industriales, Universidad de Castilla-La Mancha, Albacete 02071, Spain

Sensors 2015, 15(6), 12651-12667; https://doi.org/10.3390/s150612651 - 28 May 2015

Cited by 6 | Viewed by 5659

Abstract

This paper describes a new low-cost means to detect and locate mechanical impacts (collisions) on a 3D metal-based structure. We employ the simple and reasonably hypothesis that the use of a homogeneous material will allow certain details of the impact to be automatically [...] Read more.

This paper describes a new low-cost means to detect and locate mechanical impacts (collisions) on a 3D metal-based structure. We employ the simple and reasonably hypothesis that the use of a homogeneous material will allow certain details of the impact to be automatically determined by measuring the time delays of acoustic wave propagation throughout the 3D structure. The location of strategic piezoelectric sensors on the structure and an electronic-computerized system has allowed us to determine the instant and position at which the impact is produced. The proposed automatic system allows us to fully integrate impact point detection and the task of inspecting the point or zone at which this impact occurs. What is more, the proposed method can be easily integrated into a robot-based inspection system capable of moving over 3D metallic structures, thus avoiding (or minimizing) the need for direct human intervention. Experimental results are provided to show the effectiveness of the proposed approach. Full article

(This article belongs to the Special Issue Acoustic Waveguide Sensors)

▼ Show Figures

Figure 1

14 pages, 906 KiB

Open AccessArticle

An Optical Biosensor from Green Fluorescent Escherichia coli for the Evaluation of Single and Combined Heavy Metal Toxicities

by Dedi Futra¹, Lee Yook Heng^1,2,*, Asmat Ahmad¹, Salmijah Surif¹ and Tan Ling Ling²

¹ School of Chemical Science and Food Technolgoy, Faculty of Science, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E., Malaysia

² Southeast Asia Disaster Prevention Research Initiative (SEADPRI-UKM), LESTARI, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E., Malaysia

Sensors 2015, 15(6), 12668-12681; https://doi.org/10.3390/s150612668 - 28 May 2015

Cited by 19 | Viewed by 7124

Abstract

A fluorescence-based fiber optic toxicity biosensor based on genetically modified Escherichia coli (E. coli) with green fluorescent protein (GFP) was developed for the evaluation of the toxicity of several hazardous heavy metal ions. The toxic metals include Cu(II), Cd(II), Pb(II), Zn(II), [...] Read more.

A fluorescence-based fiber optic toxicity biosensor based on genetically modified Escherichia coli (E. coli) with green fluorescent protein (GFP) was developed for the evaluation of the toxicity of several hazardous heavy metal ions. The toxic metals include Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(III). The optimum fluorescence excitation and emission wavelengths of the optical biosensor were 400 ± 2 nm and 485 ± 2 nm, respectively. Based on the toxicity observed under optimal conditions, the detection limits of Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(III) that can be detected using the toxicity biosensor were at 0.04, 0.32, 0.46, 2.80, 100, 250, 400, 720 and 2600 μg/L, respectively. The repeatability and reproducibility of the proposed biosensor were 3.5%–4.8% RSD (relative standard deviation) and 3.6%–5.1% RSD (n = 8), respectively. The biosensor response was stable for at least five weeks, and demonstrated higher sensitivity towards metal toxicity evaluation when compared to a conventional Microtox assay. Full article

(This article belongs to the Special Issue Advances in Optical Biosensors)

▼ Show Figures

Figure 1

18 pages, 16546 KiB

Open AccessArticle

Airborne Relay-Based Regional Positioning System

by Kyuman Lee¹

, Hongjun Noh² and Jaesung Lim^1,*

¹ Department of Computer Engineering, Ajou University, 206 World cup-ro, Yeongtong-gu, Suwon 443-749, Korea

² Communication Research Center, LIG Nex1, 333 Pangyo-ro, Bundang-gu, Seongnam 463-400, Korea

Sensors 2015, 15(6), 12682-12699; https://doi.org/10.3390/s150612682 - 28 May 2015

Cited by 17 | Viewed by 6129

Abstract

Ground-based pseudolite systems have some limitations, such as low vertical accuracy, multipath effects and near-far problems. These problems are not significant in airborne-based pseudolite systems. However, the monitoring of pseudolite positions is required because of the mobility of the platforms on which the [...] Read more.

Ground-based pseudolite systems have some limitations, such as low vertical accuracy, multipath effects and near-far problems. These problems are not significant in airborne-based pseudolite systems. However, the monitoring of pseudolite positions is required because of the mobility of the platforms on which the pseudolites are mounted, and this causes performance degradation. To address these pseudolite system limitations, we propose an airborne relay-based regional positioning system that consists of a master station, reference stations, airborne relays and a user. In the proposed system, navigation signals are generated from the reference stations located on the ground and are relayed via the airborne relays. Unlike in conventional airborne-based systems, the user in the proposed system sequentially estimates both the locations of airborne relays and his/her own position. Therefore, a delay due to monitoring does not occur, and the accuracy is not affected by the movement of airborne relays. We conducted several simulations to evaluate the performance of the proposed system. Based on the simulation results, we demonstrated that the proposed system guarantees a higher accuracy than airborne-based pseudolite systems, and it is feasible despite the existence of clock offsets among reference stations. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

20 pages, 3143 KiB

Open AccessArticle

A Programmable High-Voltage Compliance Neural Stimulator for Deep Brain Stimulation in Vivo

by Cihun-Siyong Alex Gong^1,2

, Hsin-Yi Lai^3,4,*,†, Sy-Han Huang⁵, Yu-Chun Lo⁶, Nicole Lee⁷, Pin-Yuan Chen⁸, Po-Hsun Tu⁸, Chia-Yen Yang⁹, James Chang-Chieh Lin¹ and You-Yin Chen^5,*,†

¹ Department of Electrical Engineering, Chang Gung University, No. 259 Wen-Hwa 1st Rd., Guishan Township, Taoyuan County 333, Taiwan

² Portable Energy System Group, Green Technology Research Center, College of Engineering, Chang Gung University, No. 259 Wen-Hwa 1st Rd., Guishan Township, Taoyuan County 333, Taiwan

³ Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University, Zhouyiqing Building, Yuquan Campus, Zhejiang University, Hangzhou 310027, China

⁴ School of Medicine, Chang Gung University, No. 259 Wen-Hwa 1st Rd., Guishan Township, Taoyuan County 333, Taiwan

⁵ Department of Biomedical Engineering, National Yang Ming University, No.155, Sec.2, Linong St., Taipei 112, Taiwan

⁶ Center for Optoelectronic Medicine, National Taiwan University College of Medicine, No.1 Jen Ai Rd. Sec. 1. Taipei 100, Taiwan

⁷ Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive #0412, La Jolla, CA 92093, USA

⁸ Department of Neurosurgery, Chang Gung University and Memorial Hospital at Linkou, No.5, Fuxing St., Guishan Township, Taoyuan County 333, Taiwan

⁹ Department of Biomedical Engineering, Ming-Chuan University, 5 De Ming Rd., Guishan Township, Taoyuan County 333, Taiwan

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 12700-12719; https://doi.org/10.3390/s150612700 - 28 May 2015

Cited by 10 | Viewed by 10103

Abstract

Deep brain stimulation (DBS) is one of the most effective therapies for movement and other disorders. The DBS neurosurgical procedure involves the implantation of a DBS device and a battery-operated neurotransmitter, which delivers electrical impulses to treatment targets through implanted electrodes. The DBS [...] Read more.

Deep brain stimulation (DBS) is one of the most effective therapies for movement and other disorders. The DBS neurosurgical procedure involves the implantation of a DBS device and a battery-operated neurotransmitter, which delivers electrical impulses to treatment targets through implanted electrodes. The DBS modulates the neuronal activities in the brain nucleus for improving physiological responses as long as an electric discharge above the stimulation threshold can be achieved. In an effort to improve the performance of an implanted DBS device, the device size, implementation cost, and power efficiency are among the most important DBS device design aspects. This study aims to present preliminary research results of an efficient stimulator, with emphasis on conversion efficiency. The prototype stimulator features high-voltage compliance, implemented with only a standard semiconductor process, without the use of extra masks in the foundry through our proposed circuit structure. The results of animal experiments, including evaluation of evoked responses induced by thalamic electrical stimuli with our fabricated chip, were shown to demonstrate the proof of concept of our design. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

16 pages, 815 KiB

Open AccessArticle

An Efficient and Reliable Geographic Routing Protocol Based on Partial Network Coding for Underwater Sensor Networks

by Kun Hao^1,*, Zhigang Jin^2,*

, Haifeng Shen³ and Ying Wang²

¹ School of Computer and Information Engineering, Tianjin ChengJian University, 300384 Tianjin, China

² School of Electronic Information Engineering, Tianjin University, 300072 Tianjin, China

³ School of Computer Science, Engineering and Mathematics, Flinders University, 5001 Adelaide, Australia

Sensors 2015, 15(6), 12720-12735; https://doi.org/10.3390/s150612720 - 28 May 2015

Cited by 39 | Viewed by 5909

Abstract

Efficient routing protocols for data packet delivery are crucial to underwater sensor networks (UWSNs). However, communication in UWSNs is a challenging task because of the characteristics of the acoustic channel. Network coding is a promising technique for efficient data packet delivery thanks to [...] Read more.

Efficient routing protocols for data packet delivery are crucial to underwater sensor networks (UWSNs). However, communication in UWSNs is a challenging task because of the characteristics of the acoustic channel. Network coding is a promising technique for efficient data packet delivery thanks to the broadcast nature of acoustic channels and the relatively high computation capabilities of the sensor nodes. In this work, we present GPNC, a novel geographic routing protocol for UWSNs that incorporates partial network coding to encode data packets and uses sensor nodes’ location information to greedily forward data packets to sink nodes. GPNC can effectively reduce network delays and retransmissions of redundant packets causing additional network energy consumption. Simulation results show that GPNC can significantly improve network throughput and packet delivery ratio, while reducing energy consumption and network latency when compared with other routing protocols. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

29 pages, 2272 KiB

Open AccessArticle

Reaction Diffusion Voronoi Diagrams: From Sensors Data to Computing

by Alejandro Vázquez-Otero^1,2,*, Jan Faigl³

, Raquel Dormido¹

and Natividad Duro¹

¹ Department of Computer Sciences and Automatic Control, UNED, C/ Juan del Rosal, 16, Madrid 28040, Spain

² Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic

³ Department of Computer Science, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, 16627 Prague 6, Czech Republic

Sensors 2015, 15(6), 12736-12764; https://doi.org/10.3390/s150612736 - 29 May 2015

Cited by 5 | Viewed by 8537

Abstract

In this paper, a new method to solve computational problems using reaction diffusion (RD) systems is presented. The novelty relies on the use of a model configuration that tailors its spatiotemporal dynamics to develop Voronoi diagrams (VD) as a part of the system’s [...] Read more.

In this paper, a new method to solve computational problems using reaction diffusion (RD) systems is presented. The novelty relies on the use of a model configuration that tailors its spatiotemporal dynamics to develop Voronoi diagrams (VD) as a part of the system’s natural evolution. The proposed framework is deployed in a solution of related robotic problems, where the generalized VD are used to identify topological places in a grid map of the environment that is created from sensor measurements. The ability of the RD-based computation to integrate external information, like a grid map representing the environment in the model computational grid, permits a direct integration of sensor data into the model dynamics. The experimental results indicate that this method exhibits significantly less sensitivity to noisy data than the standard algorithms for determining VD in a grid. In addition, previous drawbacks of the computational algorithms based on RD models, like the generation of volatile solutions by means of excitable waves, are now overcome by final stable states. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

17 pages, 3392 KiB

Open AccessArticle

Provisioning Vehicular Services and Communications Based on a Bluetooth Sensor Network Deployment

by David Perez-Diaz De Cerio^*

and José Luis Valenzuela

Universitat Politècnica de Catalunya, C/Esteve Terrades 7, Castelldefels 08860, Spain

Sensors 2015, 15(6), 12765-12781; https://doi.org/10.3390/s150612765 - 29 May 2015

Cited by 10 | Viewed by 7774

Abstract

It is very common to rule out Bluetooth as a suitable technology for vehicular communications. The reasons behind this decision usually result from misconceptions such as accepting that Bluetooth has a short application range, or assuming its connection setup is not fast enough [...] Read more.

It is very common to rule out Bluetooth as a suitable technology for vehicular communications. The reasons behind this decision usually result from misconceptions such as accepting that Bluetooth has a short application range, or assuming its connection setup is not fast enough to allow communication which involves high speed moving nodes. This paper refutes those assertions and proposes the use of Bluetooth not only for Infrastructure-to-Vehicle (I2V) or Road-to-Vehicle (R2V) communications, but also for Vehicle-to-Vehicle (V2V) or Vehicle-to-Infrastructure (V2I) communications. This novel proposal is based on using the remote name request procedure of the standard, combined with an adjustment and optimization of the parameters present in the inquiry and page procedures. The proposed modifications reduce the information exchange delay, thus making Bluetooth a suitable technology for high-speed vehicle communications. The feasibility of the proposed scheme has been validated through experimental tests conducted in different scenarios: laboratory, a real highway and a racing test circuit. There, the communication system was installed in a vehicle circulating at speeds of up to 250 km/h, whereas autonomous devices were disseminated throughout the road path to communicate with the on board devices obtaining satisfying results. Full article

(This article belongs to the Special Issue Sensors in New Road Vehicles)

▼ Show Figures

Graphical abstract

20 pages, 3392 KiB

Open AccessArticle

A Rapid Method to Achieve Aero-Engine Blade Form Detection

by Bin Sun and Bing Li^*

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

Sensors 2015, 15(6), 12782-12801; https://doi.org/10.3390/s150612782 - 1 Jun 2015

Cited by 42 | Viewed by 7893

Abstract

This paper proposes a rapid method to detect aero-engine blade form, according to the characteristics of an aero-engine blade surface. This method first deduces an inclination error model in free-form surface measurements based on the non-contact laser triangulation principle. Then a four-coordinate measuring [...] Read more.

This paper proposes a rapid method to detect aero-engine blade form, according to the characteristics of an aero-engine blade surface. This method first deduces an inclination error model in free-form surface measurements based on the non-contact laser triangulation principle. Then a four-coordinate measuring system was independently developed, a special fixture was designed according to the blade shape features, and a fast measurement of the blade features path was planned. Finally, by using the inclination error model for correction of acquired data, the measurement error that was caused by tilt form is compensated. As a result the measurement accuracy of the Laser Displacement Sensor was less than 10 μm. After the experimental verification, this method makes full use of optical non-contact measurement fast speed, high precision and wide measuring range of features. Using a standard gauge block as a measurement reference, the coordinate system conversion data is simple and practical. It not only improves the measurement accuracy of the blade surface, but also its measurement efficiency. Therefore, this method increases the value of the measurement of complex surfaces. Full article

(This article belongs to the Special Issue Optical Sensors for Chemical, Biological and Industrial Applications)

▼ Show Figures

Figure 1

14 pages, 3496 KiB

Open AccessArticle

Design and Evaluation of Potentiometric Principles for Bladder Volume Monitoring: A Preliminary Study

by Shih-Ching Chen^1,2, Tsung-Hsun Hsieh^3,4, Wen-Jia Fan¹, Chien-Hung Lai^1,2, Chun-Lung Chen^1,2, Wei-Feng Wei⁵ and Chih-Wei Peng^1,2,*

¹ Department of Physical Medicine and Rehabilitation, School of Medicine, College of Medicine, Taipei Medical University, No. 250, Wuxing Street, Taipei 11031, Taiwan

² Department of Physical Medicine and Rehabilitation, Taipei Medical University Hospital, No. 252, Wuxing Street, Taipei 11031, Taiwan

³ Graduate Institute of Neural Regenerative Medicine, Taipei Medical University, No. 250, Wuxing Street, Taipei 11031, Taiwan

⁴ Department of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine and Healthy Aging Research Center, Chang Gung University, No. 259, Wenhua 1st Rd, Taoyuan 33302, Taiwan

Sensors 2015, 15(6), 12802-12815; https://doi.org/10.3390/s150612802 - 1 Jun 2015

Cited by 12 | Viewed by 7541

Abstract

Recent advances in microelectronics and wireless transmission technology have led to the development of various implantable sensors for real-time monitoring of bladder conditions. Although various sensing approaches for monitoring bladder conditions were reported, most such sensors have remained at the laboratory stage due [...] Read more.

Recent advances in microelectronics and wireless transmission technology have led to the development of various implantable sensors for real-time monitoring of bladder conditions. Although various sensing approaches for monitoring bladder conditions were reported, most such sensors have remained at the laboratory stage due to the existence of vital drawbacks. In the present study, we explored a new concept for monitoring the bladder capacity on the basis of potentiometric principles. A prototype of a potentiometer module was designed and fabricated and integrated with a commercial wireless transmission module and power unit. A series of in vitro pig bladder experiments was conducted to determine the best design parameters for implementing the prototype potentiometric device and to prove its feasibility. We successfully implemented the potentiometric module in a pig bladder model in vitro, and the error of the accuracy of bladder volume detection was <±3%. Although the proposed potentiometric device was built using a commercial wireless module, the design principles and animal experience gathered from this research can serve as a basis for developing new implantable bladder sensors in the future. Full article

(This article belongs to the Special Issue Novel Biomaterials and Sensors for Tissue Engineering)

▼ Show Figures

Figure 1

18 pages, 1801 KiB

Open AccessArticle

Tightly-Coupled Stereo Visual-Inertial Navigation Using Point and Line Features

by Xianglong Kong, Wenqi Wu^*, Lilian Zhang and Yujie Wang

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

Sensors 2015, 15(6), 12816-12833; https://doi.org/10.3390/s150612816 - 1 Jun 2015

Cited by 35 | Viewed by 8499

Abstract

This paper presents a novel approach for estimating the ego-motion of a vehicle in dynamic and unknown environments using tightly-coupled inertial and visual sensors. To improve the accuracy and robustness, we exploit the combination of point and line features to aid navigation. The [...] Read more.

This paper presents a novel approach for estimating the ego-motion of a vehicle in dynamic and unknown environments using tightly-coupled inertial and visual sensors. To improve the accuracy and robustness, we exploit the combination of point and line features to aid navigation. The mathematical framework is based on trifocal geometry among image triplets, which is simple and unified for point and line features. For the fusion algorithm design, we employ the Extended Kalman Filter (EKF) for error state prediction and covariance propagation, and the Sigma Point Kalman Filter (SPKF) for robust measurement updating in the presence of high nonlinearities. The outdoor and indoor experiments show that the combination of point and line features improves the estimation accuracy and robustness compared to the algorithm using point features alone. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

7 pages, 1925 KiB

Open AccessShort Note

Supplemental Blue LED Lighting Array to Improve the Signal Quality in Hyperspectral Imaging of Plants

by Anne-Katrin Mahlein^1,*,†, Simon Hammersley^2,†, Erich-Christian Oerke¹, Heinz-Wilhelm Dehne¹, Heiner Goldbach³ and Bruce Grieve²

¹ Institute of Crop Science and Resource Conservation (INRES)-Phytomedicine, University of Bonn, Meckenheimer Allee 166a, 53115 Bonn, Germany

² School of Electrical and Electronic Engineering, University of Manchester, Oxford Road, Manchester M13 9PL, UK

³ Institute of Crop Science and Resource Conservation (INRES)-Plant Nutrition, University of Bonn, Karlrobert-Kreiten-Strasse 13, 53115 Bonn, Germany

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 12834-12840; https://doi.org/10.3390/s150612834 - 1 Jun 2015

Cited by 28 | Viewed by 7561

Abstract

Hyperspectral imaging systems used in plant science or agriculture often have suboptimal signal-to-noise ratio in the blue region (400–500 nm) of the electromagnetic spectrum. Typically there are two principal reasons for this effect, the low sensitivity of the imaging sensor and the low [...] Read more.

Hyperspectral imaging systems used in plant science or agriculture often have suboptimal signal-to-noise ratio in the blue region (400–500 nm) of the electromagnetic spectrum. Typically there are two principal reasons for this effect, the low sensitivity of the imaging sensor and the low amount of light available from the illuminating source. In plant science, the blue region contains relevant information about the physiology and the health status of a plant. We report on the improvement in sensitivity of a hyperspectral imaging system in the blue region of the spectrum by using supplemental illumination provided by an array of high brightness light emitting diodes (LEDs) with an emission peak at 470 nm. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

16 pages, 2784 KiB

Open AccessArticle

Longitudinal Modes along Thin Piezoelectric Waveguides for Liquid Sensing Applications

by Cinzia Caliendo

Istituto di Acustica e Sensori O. M. Corbino, IDASC-CNR, Via del Fosso del Cavaliere 100, 00133 Roma, Italy

Sensors 2015, 15(6), 12841-12856; https://doi.org/10.3390/s150612841 - 2 Jun 2015

Cited by 13 | Viewed by 6065

Abstract

The propagation of longitudinally polarized acoustic modes along thin piezoelectric plates (BN, ZnO, InN, AlN and GaN) is theoretically studied, aiming at the design of high frequency electroacoustic devices suitable for work in liquid environments. The investigation of the acoustic field profile across [...] Read more.

The propagation of longitudinally polarized acoustic modes along thin piezoelectric plates (BN, ZnO, InN, AlN and GaN) is theoretically studied, aiming at the design of high frequency electroacoustic devices suitable for work in liquid environments. The investigation of the acoustic field profile across the plate revealed the presence of longitudinally polarized Lamb modes, travelling at velocities close to that of the longitudinal bulk acoustic wave propagating in the same direction. Such waves are suitable for the implementation of high-frequency, low-loss electroacoustic devices operating in liquid environments. The time-averaged power flow density, the phase velocity and the electroacoustic coupling coefficient K² dispersion curves were studied, for the first (S₀) and four higher order (S₁, S₂, S₃, S₄) symmetrical modes for different electrical boundary conditions. Two electroacoustic coupling configurations were investigated, based on interdigitated transducers, with or without a metal floating electrode at the opposite plate surface. Enhanced performances, such as a K² as high as 8.5% and a phase velocity as high as 16,700 m/s, were demostrated for the ZnO- and BN-based waveguides, as an example. The relative velocity changes, and the inertial and viscous sensitivities of the first symmetric and anti-symmetric mode, S₀ and A₀, propagating along thin plates bordered by a viscous liquid were derived using the perturbation approach. The present study highlights the feasibility of the piezoelectric waveguides to the development of high-frequency, integrated-circuits compatible electroacoustic devices suitable for working in liquid environment. Full article

(This article belongs to the Special Issue Acoustic Waveguide Sensors)

▼ Show Figures

Figure 1

15 pages, 1327 KiB

Open AccessArticle

Novel Method of Detecting Movement of the Interference Fringes Using One-Dimensional PSD

by Qi Wang^1,2,*,†

, Ji Xia^3,†, Xu Liu¹ and Yong Zhao^1,2

¹ College of Information Science and Engineering, Northeastern University, Shenyang 110819, China

² State Key Laboratory of Synthetical Automation for Process Industries, Northeastern University, Shenyang 110819, China

³ Academy of Ocean Science and Engineering, National University of Defense Technology, College of Optoelectronic Science and Engineering, Changsha 410073, China

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 12857-12871; https://doi.org/10.3390/s150612857 - 2 Jun 2015

Cited by 3 | Viewed by 5827

Abstract

In this paper, a method of using a one-dimensional position-sensitive detector (PSD) by replacing charge-coupled device (CCD) to measure the movement of the interference fringes is presented first, and its feasibility is demonstrated through an experimental setup based on the principle of centroid [...] Read more.

In this paper, a method of using a one-dimensional position-sensitive detector (PSD) by replacing charge-coupled device (CCD) to measure the movement of the interference fringes is presented first, and its feasibility is demonstrated through an experimental setup based on the principle of centroid detection. Firstly, the centroid position of the interference fringes in a fiber Mach-Zehnder (M-Z) interferometer is solved in theory, showing it has a higher resolution and sensitivity. According to the physical characteristics and principles of PSD, a simulation of the interference fringe’s phase difference in fiber M-Z interferometers and PSD output is carried out. Comparing the simulation results with the relationship between phase differences and centroid positions in fiber M-Z interferometers, the conclusion that the output of interference fringes by PSD is still the centroid position is obtained. Based on massive measurements, the best resolution of the system is achieved with 5.15, 625 μm. Finally, the detection system is evaluated through setup error analysis and an ultra-narrow-band filter structure. The filter structure is configured with a one-dimensional photonic crystal containing positive and negative refraction material, which can eliminate background light in the PSD detection experiment. This detection system has a simple structure, good stability, high precision and easily performs remote measurements, which makes it potentially useful in material small deformation tests, refractivity measurements of optical media and optical wave front detection. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

12 pages, 2070 KiB

Open AccessArticle

Quantum Dot-Based Molecular Beacon to Monitor Intracellular MicroRNAs

by Jonghwan Lee^1,2,†, Sung Ung Moon^1,2,†, Yong Seung Lee^1,2, Bahy A. Ali^3,4, Abdulaziz A. Al-Khedhairy⁵, Daoud Ali⁵, Javed Ahmed³, Abdullah M. Al Salem³ and Soonhag Kim^1,2,*

¹ Institute for Bio-Medical Convergence, College of Medicine, Kwandong Catholic University, Gangneung-si, Gangwon-do 270-701, Korea

² Catholic Kwandong University International St. Mary's Hospital, Incheon Metropolitan City 404-834, Korea

³ Aljeraisy DNA Research Chair, Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia

⁴ Department of Nucleic Acids Research, Genetic Engineering and Biotechnology Research Institute, City for Scientific Research and Technological Applications, Alexandria 21934, Egypt

⁵ Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 12872-12883; https://doi.org/10.3390/s150612872 - 2 Jun 2015

Cited by 23 | Viewed by 7767

Abstract

Fluorescence monitoring of endogenous microRNA (miRNA or miR) activity related to neuronal development using nano-sized materials provides crucial information on miRNA expression patterns in a noninvasive manner. In this study, we report a new method to monitor intracellular miRNA124a using quantum dot-based molecular [...] Read more.

Fluorescence monitoring of endogenous microRNA (miRNA or miR) activity related to neuronal development using nano-sized materials provides crucial information on miRNA expression patterns in a noninvasive manner. In this study, we report a new method to monitor intracellular miRNA124a using quantum dot-based molecular beacon (R9-QD-miR124a beacon). The R9-QD-miR124a beacon was constructed using QDs and two probes, miR124a-targeting oligomer and arginine rich cell-penetrating peptide (R9 peptide). The miR124a-targeting oligomer contains a miR124a binging sequence and a black hole quencher 1 (BHQ1). In the absence of target miR124a, the R9-QD-miR124a beacon forms a partial duplex beacon and remained in quenched state because the BHQ1 quenches the fluorescence signal of the R9-QD-miR124a beacon. The binding of miR124a to the miR124a binding sequence of the miR124a-targeting oligomer triggered the separation of the BHQ1 quencher and subsequent signal-on of a red fluorescence signal. Moreover, enhanced cellular uptake was achieved by conjugation with the R9 peptide, which resulted in increased fluorescent signal of the R9-QD-miR124a beacons in P19 cells during neurogenesis due to the endogenous expression of miR124a. Full article

(This article belongs to the Special Issue Intracellular Sensing)

▼ Show Figures

Figure 1

7 pages, 799 KiB

Open AccessArticle

Research on the Interaction of Hydrogen-Bond Acidic Polymer Sensitive Sensor Materials with Chemical Warfare Agents Simulants by Inverse Gas Chromatography

by Liu Yang^1,*,†, Qiang Han^2,†, Shuya Cao¹, Feng Huang¹, Molin Qin¹, Chenghai Guo¹ and Mingyu Ding²

¹ State Key Laboratory of NBC Protection for Civilians, Beijing 102205, China

² Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University, Beijing 100084, China

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 12884-12890; https://doi.org/10.3390/s150612884 - 2 Jun 2015

Cited by 4 | Viewed by 5184

Abstract

Hydrogen-bond acidic polymers are important high affinity materials sensitive to organophosphates in the chemical warfare agent sensor detection process. Interactions between the sensor sensitive materials and chemical warfare agent simulants were studied by inverse gas chromatography. Hydrogen bonded acidic polymers, i.e., BSP3, [...] Read more.

Hydrogen-bond acidic polymers are important high affinity materials sensitive to organophosphates in the chemical warfare agent sensor detection process. Interactions between the sensor sensitive materials and chemical warfare agent simulants were studied by inverse gas chromatography. Hydrogen bonded acidic polymers, i.e., BSP3, were prepared for micro-packed columns to examine the interaction. DMMP (a nerve gas simulant) and 2-CEES (a blister agent simulant) were used as probes. Chemical and physical parameters such as heats of absorption and Henry constants of the polymers to DMMP and 2-CEES were determined by inverse gas chromatography. Details concerning absorption performance are also discussed in this paper. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

Figure 1

15 pages, 1649 KiB

Open AccessArticle

Colorimetric-Based Detection of TNT Explosives Using Functionalized Silica Nanoparticles

by Noorhayati Idros^1,2, Man Yi Ho^1,3, Mike Pivnenko¹, Malik M. Qasim¹, Hua Xu⁴, Zhongze Gu⁴ and Daping Chu^1,*

¹ Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK

² Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Lot 106, 108 & 110, Tingkat 1, Block A, Taman Pertiwi Indah, Jalan Kangar-Alor Setar, Seriab 01000 Kangar, Perlis, Malaysia

³ Schlumberger Cambridge Research, High Cross, Madingley Road, Cambridge CB3 0EL, UK

⁴ State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Sipailou 2, Nanjing 210096, China

Sensors 2015, 15(6), 12891-12905; https://doi.org/10.3390/s150612891 - 3 Jun 2015

Cited by 32 | Viewed by 10605

Abstract

This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO₂ [...] Read more.

This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO₂-NH₂) acts as a capturing probe for TNT target binding to form Meisenheimer amine–TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO₂-NH₂ nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10⁻¹² to 10⁻⁴ molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range. Full article

(This article belongs to the Special Issue Chemo- and Biosensors for Security and Defense)

▼ Show Figures

Figure 1

26 pages, 723 KiB

Open AccessArticle

A MAC Protocol for Medical Monitoring Applications of Wireless Body Area Networks

by Minglei Shu^1,2, Dongfeng Yuan¹, Chongqing Zhang^2,3,*, Yinglong Wang² and Changfang Chen²

¹ School of Information Science and Engineering, Shandong University, Jinan 250100, China

² Shandong Provincial Key Laboratory of Computer Networks, Shandong Computer Science Center (National Supercomputer Center in Jinan), Jinan 250101, China

³ College of Information Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China

Sensors 2015, 15(6), 12906-12931; https://doi.org/10.3390/s150612906 - 3 Jun 2015

Cited by 56 | Viewed by 6190

Abstract

Targeting the medical monitoring applications of wireless body area networks (WBANs), a hybrid medium access control protocol using an interrupt mechanism (I-MAC) is proposed to improve the energy and time slot utilization efficiency and to meet the data delivery delay requirement at the [...] Read more.

Targeting the medical monitoring applications of wireless body area networks (WBANs), a hybrid medium access control protocol using an interrupt mechanism (I-MAC) is proposed to improve the energy and time slot utilization efficiency and to meet the data delivery delay requirement at the same time. Unlike existing hybrid MAC protocols, a superframe structure with a longer length is adopted to avoid unnecessary beacons. The time slots are mostly allocated to nodes with periodic data sources. Short interruption slots are inserted into the superframe to convey the urgent data and to guarantee the real-time requirements of these data. During these interruption slots, the coordinator can break the running superframe and start a new superframe. A contention access period (CAP) is only activated when there are more data that need to be delivered. Experimental results show the effectiveness of the proposed MAC protocol in WBANs with low urgent traffic. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

27 pages, 976 KiB

Open AccessArticle

GTRF: A Game Theory Approach for Regulating Node Behavior in Real-Time Wireless Sensor Networks

by Chi Lin^*, Guowei Wu and Poria Pirozmand

School of Software, Dalian University of Technology, Road No. 8, Development Zone, Dalian 116620, China

Sensors 2015, 15(6), 12932-12958; https://doi.org/10.3390/s150612932 - 4 Jun 2015

Cited by 6 | Viewed by 5374

Abstract

The selfish behaviors of nodes (or selfish nodes) cause packet loss, network congestion or even void regions in real-time wireless sensor networks, which greatly decrease the network performance. Previous methods have focused on detecting selfish nodes or avoiding selfish behavior, but little attention [...] Read more.

The selfish behaviors of nodes (or selfish nodes) cause packet loss, network congestion or even void regions in real-time wireless sensor networks, which greatly decrease the network performance. Previous methods have focused on detecting selfish nodes or avoiding selfish behavior, but little attention has been paid to regulating selfish behavior. In this paper, a Game Theory-based Real-time & Fault-tolerant (GTRF) routing protocol is proposed. GTRF is composed of two stages. In the first stage, a game theory model named VA is developed to regulate nodes’ behaviors and meanwhile balance energy cost. In the second stage, a jumping transmission method is adopted, which ensures that real-time packets can be successfully delivered to the sink before a specific deadline. We prove that GTRF theoretically meets real-time requirements with low energy cost. Finally, extensive simulations are conducted to demonstrate the performance of our scheme. Simulation results show that GTRF not only balances the energy cost of the network, but also prolongs network lifetime. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

24 pages, 5178 KiB

Open AccessArticle

Visual Privacy by Context: Proposal and Evaluation of a Level-Based Visualisation Scheme

by José Ramón Padilla-López¹, Alexandros Andre Chaaraoui¹, Feng Gu² and Francisco Flórez-Revuelta^1,2,*

¹ Department of Computer Technology, University of Alicante, P.O. Box 99, E-03080 Alicante, Spain

² Faculty of Science, Engineering and Computing, Kingston University, Penrhyn Road, KT1 2EE Kingston upon Thames, UK

Sensors 2015, 15(6), 12959-12982; https://doi.org/10.3390/s150612959 - 4 Jun 2015

Cited by 45 | Viewed by 7805

Abstract

Privacy in image and video data has become an important subject since cameras are being installed in an increasing number of public and private spaces. Specifically, in assisted living, intelligent monitoring based on computer vision can allow one to provide risk detection and [...] Read more.

Privacy in image and video data has become an important subject since cameras are being installed in an increasing number of public and private spaces. Specifically, in assisted living, intelligent monitoring based on computer vision can allow one to provide risk detection and support services that increase people’s autonomy at home. In the present work, a level-based visualisation scheme is proposed to provide visual privacy when human intervention is necessary, such as at telerehabilitation and safety assessment applications. Visualisation levels are dynamically selected based on the previously modelled context. In this way, different levels of protection can be provided, maintaining the necessary intelligibility required for the applications. Furthermore, a case study of a living room, where a top-view camera is installed, is presented. Finally, the performed survey-based evaluation indicates the degree of protection provided by the different visualisation models, as well as the personal privacy preferences and valuations of the users. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

▼ Show Figures

16 pages, 3684 KiB

Open AccessReview

Magnetic-Particle-Sensing Based Diagnostic Protocols and Applications

by Tsukasa Takamura^1,*, Pil Ju Ko², Jaiyam Sharma³, Ryoji Yukino³, Shunji Ishizawa³ and Adarsh Sandhu^1,2,4

¹ Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580, Japan

² Research Promotion Center, The University of Electro-Communications, 1-5-1 Chofugaoka Chofu, Tokyo 182-8585, Japan

³ Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580, Japan

⁴ Department of Engineering Science, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan

Sensors 2015, 15(6), 12983-12998; https://doi.org/10.3390/s150612983 - 4 Jun 2015

Cited by 15 | Viewed by 8229

Abstract

Magnetic particle-labeled biomaterial detection has attracted much attention in recent years for a number of reasons; easy manipulation by external magnetic fields, easy functionalization of the surface, and large surface-to-volume ratio, to name but a few. In this review, we report on our [...] Read more.

Magnetic particle-labeled biomaterial detection has attracted much attention in recent years for a number of reasons; easy manipulation by external magnetic fields, easy functionalization of the surface, and large surface-to-volume ratio, to name but a few. In this review, we report on our recent investigations into the detection of nano-sized magnetic particles. First, the detection by Hall magnetic sensor with lock-in amplifier and alternative magnetic field is summarized. Then, our approach to detect sub-200 nm diameter target magnetic particles via relatively large micoro-sized “columnar particles” by optical microscopy is described. Subsequently, we summarize magnetic particle detection based on optical techniques; one method is based on the scattering of the magnetically-assembled nano-sized magnetic bead chain in rotating magnetic fields and the other one is based on the reflection of magnetic target particles and porous silicon. Finally, we report recent works with reference to more familiar industrial products (such as smartphone-based medical diagnosis systems and magnetic removal of unspecific-binded nano-sized particles, or “magnetic washing”). Full article

(This article belongs to the Special Issue Inorganic Nanoparticles as Biomedical Probes)

▼ Show Figures

Figure 1

13 pages, 3004 KiB

Open AccessArticle

Matching the Best Viewing Angle in Depth Cameras for Biomass Estimation Based on Poplar Seedling Geometry

by Dionisio Andújar^*, César Fernández-Quintanilla and José Dorado

Institute of Agricultural Sciences, CSIC, Madrid 28006, Spain

Sensors 2015, 15(6), 12999-13011; https://doi.org/10.3390/s150612999 - 4 Jun 2015

Cited by 26 | Viewed by 7672

Abstract

In energy crops for biomass production a proper plant structure is important to optimize wood yields. A precise crop characterization in early stages may contribute to the choice of proper cropping techniques. This study assesses the potential of the Microsoft Kinect for Windows [...] Read more.

In energy crops for biomass production a proper plant structure is important to optimize wood yields. A precise crop characterization in early stages may contribute to the choice of proper cropping techniques. This study assesses the potential of the Microsoft Kinect for Windows v.1 sensor to determine the best viewing angle of the sensor to estimate the plant biomass based on poplar seedling geometry. Kinect Fusion algorithms were used to generate a 3D point cloud from the depth video stream. The sensor was mounted in different positions facing the tree in order to obtain depth (RGB-D) images from different angles. Individuals of two different ages, e.g., one month and one year old, were scanned. Four different viewing angles were compared: top view (0°), 45° downwards view, front view (90°) and ground upwards view (−45°). The ground-truth used to validate the sensor readings consisted of a destructive sampling in which the height, leaf area and biomass (dry weight basis) were measured in each individual plant. The depth image models agreed well with 45°, 90° and −45° measurements in one-year poplar trees. Good correlations (0.88 to 0.92) between dry biomass and the area measured with the Kinect were found. In addition, plant height was accurately estimated with a few centimeters error. The comparison between different viewing angles revealed that top views showed poorer results due to the fact the top leaves occluded the rest of the tree. However, the other views led to good results. Conversely, small poplars showed better correlations with actual parameters from the top view (0°). Therefore, although the Microsoft Kinect for Windows v.1 sensor provides good opportunities for biomass estimation, the viewing angle must be chosen taking into account the developmental stage of the crop and the desired parameters. The results of this study indicate that Kinect is a promising tool for a rapid canopy characterization, i.e., for estimating crop biomass production, with several important advantages: low cost, low power needs and a high frame rate (frames per second) when dynamic measurements are required. Full article

(This article belongs to the Special Issue Agriculture and Forestry: Sensors, Technologies and Procedures)

▼ Show Figures

Graphical abstract

16 pages, 1561 KiB

Open AccessArticle

Design and Development of nEMoS, an All-in-One, Low-Cost, Web-Connected and 3D-Printed Device for Environmental Analysis

by Francesco Salamone^*

, Lorenzo Belussi^†

, Ludovico Danza^†

, Matteo Ghellere^† and Italo Meroni^†

¹ Construction Technologies Institute, National Research Council of Italy (ITC-CNR), Via Lombardia, 49, 20098 San Giuliano Milanese (MI), Italy

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 13012-13027; https://doi.org/10.3390/s150613012 - 4 Jun 2015

Cited by 63 | Viewed by 9672

Abstract

The Indoor Environmental Quality (IEQ) refers to the quality of the environment in relation to the health and well-being of the occupants. It is a holistic concept, which considers several categories, each related to a specific environmental parameter. This article describes a low-cost [...] Read more.

The Indoor Environmental Quality (IEQ) refers to the quality of the environment in relation to the health and well-being of the occupants. It is a holistic concept, which considers several categories, each related to a specific environmental parameter. This article describes a low-cost and open-source hardware architecture able to detect the indoor variables necessary for the IEQ calculation as an alternative to the traditional hardware used for this purpose. The system consists of some sensors and an Arduino board. One of the key strengths of Arduino is the possibility it affords of loading the script into the board’s memory and letting it run without interfacing with computers, thus granting complete independence, portability and accuracy. Recent works have demonstrated that the cost of scientific equipment can be reduced by applying open-source principles to their design using a combination of the Arduino platform and a 3D printer. The evolution of the 3D printer has provided a new means of open design capable of accelerating self-directed development. The proposed nano Environmental Monitoring System (nEMoS) instrument is shown to have good reliability and it provides the foundation for a more critical approach to the use of professional sensors as well as for conceiving new scenarios and potential applications. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

▼ Show Figures

Figure 1

24 pages, 3238 KiB

Open AccessReview

QD-Based FRET Probes at a Glance

by Armen Shamirian, Aashima Ghai and Preston T. Snee^*

Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor St., Chicago, IL 60607-7061, USA

Sensors 2015, 15(6), 13028-13051; https://doi.org/10.3390/s150613028 - 4 Jun 2015

Cited by 57 | Viewed by 13364

Abstract

The unique optoelectronic properties of quantum dots (QDs) give them significant advantages over traditional organic dyes, not only as fluorescent labels for bioimaging, but also as emissive sensing probes. QD sensors that function via manipulation of fluorescent resonance energy transfer (FRET) are of [...] Read more.

The unique optoelectronic properties of quantum dots (QDs) give them significant advantages over traditional organic dyes, not only as fluorescent labels for bioimaging, but also as emissive sensing probes. QD sensors that function via manipulation of fluorescent resonance energy transfer (FRET) are of special interest due to the multiple response mechanisms that may be utilized, which in turn imparts enhanced flexibility in their design. They may also function as ratiometric, or “color-changing” probes. In this review, we describe the fundamentals of FRET and provide examples of QD-FRET sensors as grouped by their response mechanisms such as link cleavage and structural rearrangement. An overview of early works, recent advances, and various models of QD-FRET sensors for the measurement of pH and oxygen, as well as the presence of metal ions and proteins such as enzymes, are also provided. Full article

(This article belongs to the Special Issue FRET Biosensors)

▼ Show Figures

Figure 1

17 pages, 7022 KiB

Open AccessArticle

Generation of Red-Shifted Cameleons for Imaging Ca²⁺ Dynamics of the Endoplasmic Reticulum

by Markus Waldeck-Weiermair^*, Helmut Bischof, Sandra Blass, Andras T. Deak, Christiane Klec

, Thomas Graier, Clara Roller, Rene Rost, Emrah Eroglu, Benjamin Gottschalk, Nicole A. Hofmann, Wolfgang F. Graier

and Roland Malli

Institute of Molecular Biology and Biochemistry, Centre of Molecular Medicine, Medical University of Graz, Harrachgasse 21, 8010 Graz, Austria

Sensors 2015, 15(6), 13052-13068; https://doi.org/10.3390/s150613052 - 4 Jun 2015

Cited by 31 | Viewed by 10122

Abstract

Cameleons are sophisticated genetically encoded fluorescent probes that allow quantifying cellular Ca²⁺ signals. The probes are based on Förster resonance energy transfer (FRET) between terminally located fluorescent proteins (FPs), which move together upon binding of Ca²⁺ to the central calmodulin myosin [...] Read more.

Cameleons are sophisticated genetically encoded fluorescent probes that allow quantifying cellular Ca²⁺ signals. The probes are based on Förster resonance energy transfer (FRET) between terminally located fluorescent proteins (FPs), which move together upon binding of Ca²⁺ to the central calmodulin myosin light chain kinase M13 domain. Most of the available cameleons consist of cyan and yellow FPs (CFP and YFP) as the FRET pair. However, red-shifted versions with green and orange or red FPs (GFP, OFP, RFP) have some advantages such as less phototoxicity and minimal spectral overlay with autofluorescence of cells and fura-2, a prominent chemical Ca²⁺ indicator. While GFP/OFP- or GFP/RFP-based cameleons have been successfully used to study cytosolic and mitochondrial Ca²⁺ signals, red-shifted cameleons to visualize Ca²⁺ dynamics of the endoplasmic reticulum (ER) have not been developed so far. In this study, we generated and tested several ER targeted red-shifted cameleons. Our results show that GFP/OFP-based cameleons due to miss-targeting and their high Ca²⁺ binding affinity are inappropriate to record ER Ca²⁺ signals. However, ER targeted GFP/RFP-based probes were suitable to sense ER Ca²⁺ in a reliable manner. With this study we increased the palette of cameleons for visualizing Ca²⁺ dynamics within the main intracellular Ca²⁺ store. Full article

(This article belongs to the Special Issue FRET Biosensors)

▼ Show Figures

28 pages, 933 KiB

Open AccessReview

Using a Smart City IoT to Incentivise and Target Shifts in Mobility Behaviour—Is It a Piece of Pie?

by Stefan Poslad^*, Athen Ma, Zhenchen Wang and Haibo Mei

School of Electronic Engineering and Computer Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK

Sensors 2015, 15(6), 13069-13096; https://doi.org/10.3390/s150613069 - 4 Jun 2015

Cited by 88 | Viewed by 12980

Abstract

Whilst there is an increasing capability to instrument smart cities using fixed and mobile sensors to produce the big data to better understand and manage transportation use, there still exists a wide gap between the sustainability goals of smart cities, e.g., to promote [...] Read more.

Whilst there is an increasing capability to instrument smart cities using fixed and mobile sensors to produce the big data to better understand and manage transportation use, there still exists a wide gap between the sustainability goals of smart cities, e.g., to promote less private car use at peak times, with respect to their ability to more dynamically support individualised shifts in multi-modal transportation use to help achieve such goals. We describe the development of the tripzoom system developed as part of the SUNSET—SUstainable social Network SErvices for Transport—project to research and develop a mobile and fixed traffic sensor system to help facilitate individual mobility shifts. Its main novelty was its ability to use mobile sensors to classify common multiple urban transportation modes, to generate information-rich individual and group mobility profiles and to couple this with the use of a targeted incentivised marketplace to gamify travel. This helps to promote mobility shifts towards achieving sustainability goals. This system was trialled in three European country cities operated as Living Labs over six months. Our main findings were that we were able to accomplish a level of behavioural shifts in travel behaviour. Hence, we have provided a proof-of-concept system that uses positive incentives to change individual travel behaviour. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

▼ Show Figures

Figure 1

13 pages, 7152 KiB

Open AccessReview

Review of Research Status and Development Trends of Wireless Passive LC Resonant Sensors for Harsh Environments

by Chen Li^1,2, Qiulin Tan^1,2,*, Pinggang Jia²

, Wendong Zhang¹

, Jun Liu¹, Chenyang Xue² and Jijun Xiong^1,2,*

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

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

Sensors 2015, 15(6), 13097-13109; https://doi.org/10.3390/s150613097 - 4 Jun 2015

Cited by 54 | Viewed by 10405

Abstract

Measurement technology for various key parameters in harsh environments (e.g., high-temperature and biomedical applications) continues to be limited. Wireless passive LC resonant sensors offer long service life and can be suitable for harsh environments because they can transmit signals without battery power or [...] Read more.

Measurement technology for various key parameters in harsh environments (e.g., high-temperature and biomedical applications) continues to be limited. Wireless passive LC resonant sensors offer long service life and can be suitable for harsh environments because they can transmit signals without battery power or wired connections. Consequently, these devices have become the focus of many current research studies. This paper addresses recent research, key technologies, and practical applications relative to passive LC sensors used to monitor temperature, pressure, humidity, and harmful gases in harsh environments. The advantages and disadvantages of various sensor types are discussed, and prospects and challenges for future development of these sensors are presented. Full article

(This article belongs to the Special Issue Sensors for Harsh Environments)

▼ Show Figures

Figure 1

11 pages, 1840 KiB

Open AccessArticle

Signal-to-Noise Enhancement of a Nanospring Redox-Based Sensor by Lock-in Amplification

by Pavel V. Bakharev and David N. McIlroy^*

Department of Physics, University of Idaho, Moscow, ID 83844, USA

Sensors 2015, 15(6), 13110-13120; https://doi.org/10.3390/s150613110 - 4 Jun 2015

Cited by 11 | Viewed by 6185

Abstract

A significant improvement of the response characteristics of a redox chemical gas sensor (chemiresistor) constructed with a single ZnO coated silica nanospring has been achieved with the technique of lock-in signal amplification. The comparison of DC and analog lock-in amplifier (LIA) AC measurements [...] Read more.

A significant improvement of the response characteristics of a redox chemical gas sensor (chemiresistor) constructed with a single ZnO coated silica nanospring has been achieved with the technique of lock-in signal amplification. The comparison of DC and analog lock-in amplifier (LIA) AC measurements of the electrical sensor response to toluene vapor, at the ppm level, has been conducted. When operated in the DC detection mode, the sensor exhibits a relatively high sensitivity to the analyte vapor, as well as a low detection limit at the 10 ppm level. However, at 10 ppm the signal-to-noise ratio is 5 dB, which is less than desirable. When operated in the analog LIA mode, the signal-to-noise ratio at 10 ppm increases by 30 dB and extends the detection limit to the ppb range. Full article

(This article belongs to the Special Issue Gas Sensors—Designs and Applications)

▼ Show Figures

Figure 1

11 pages, 482 KiB

Open AccessArticle

An Efficient Adaptive Angle-Doppler Compensation Approach for Non-Sidelooking Airborne Radar STAP

by Mingwei Shen^1,*, Jia Yu¹, Di Wu² and Daiyin Zhu²

¹ College of Computer & Information Engineering, Hohai University, Nanjing 211100, China

² Key Laboratory of Radar Imagine and Microwave Photonics (Nanjing University of Aeronautics and Astronautics), Ministry of Education, Nanjing 210016, China

Sensors 2015, 15(6), 13121-13131; https://doi.org/10.3390/s150613121 - 4 Jun 2015

Cited by 8 | Viewed by 5215

Abstract

In this study, the effects of non-sidelooking airborne radar clutter dispersion on space-time adaptive processing (STAP) is considered, and an efficient adaptive angle-Doppler compensation (EAADC) approach is proposed to improve the clutter suppression performance. In order to reduce the computational complexity, the reduced-dimension [...] Read more.

In this study, the effects of non-sidelooking airborne radar clutter dispersion on space-time adaptive processing (STAP) is considered, and an efficient adaptive angle-Doppler compensation (EAADC) approach is proposed to improve the clutter suppression performance. In order to reduce the computational complexity, the reduced-dimension sparse reconstruction (RDSR) technique is introduced into the angle-Doppler spectrum estimation to extract the required parameters for compensating the clutter spectral center misalignment. Simulation results to demonstrate the effectiveness of the proposed algorithm are presented. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Graphical abstract

27 pages, 1695 KiB

Open AccessArticle

Using K-Nearest Neighbor Classification to Diagnose Abnormal Lung Sounds

by Chin-Hsing Chen¹, Wen-Tzeng Huang², Tan-Hsu Tan³, Cheng-Chun Chang³ and Yuan-Jen Chang^1,4,*

¹ Department of Management Information Systems, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan, China

² Department of Computer Science and Information Engineering, Minghsin University of Science and Technology, Hsinchu 30401, Taiwan, China

³ Department of Electrical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan, China

⁴ Institute of Biomedical Engineering and Material Science, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan, China

Sensors 2015, 15(6), 13132-13158; https://doi.org/10.3390/s150613132 - 4 Jun 2015

Cited by 90 | Viewed by 18835

Abstract

A reported 30% of people worldwide have abnormal lung sounds, including crackles, rhonchi, and wheezes. To date, the traditional stethoscope remains the most popular tool used by physicians to diagnose such abnormal lung sounds, however, many problems arise with the use of a [...] Read more.

A reported 30% of people worldwide have abnormal lung sounds, including crackles, rhonchi, and wheezes. To date, the traditional stethoscope remains the most popular tool used by physicians to diagnose such abnormal lung sounds, however, many problems arise with the use of a stethoscope, including the effects of environmental noise, the inability to record and store lung sounds for follow-up or tracking, and the physician’s subjective diagnostic experience. This study has developed a digital stethoscope to help physicians overcome these problems when diagnosing abnormal lung sounds. In this digital system, mel-frequency cepstral coefficients (MFCCs) were used to extract the features of lung sounds, and then the K-means algorithm was used for feature clustering, to reduce the amount of data for computation. Finally, the K-nearest neighbor method was used to classify the lung sounds. The proposed system can also be used for home care: if the percentage of abnormal lung sound frames is > 30% of the whole test signal, the system can automatically warn the user to visit a physician for diagnosis. We also used bend sensors together with an amplification circuit, Bluetooth, and a microcontroller to implement a respiration detector. The respiratory signal extracted by the bend sensors can be transmitted to the computer via Bluetooth to calculate the respiratory cycle, for real-time assessment. If an abnormal status is detected, the device will warn the user automatically. Experimental results indicated that the error in respiratory cycles between measured and actual values was only 6.8%, illustrating the potential of our detector for home care applications. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

25 pages, 2768 KiB

Open AccessArticle

mDurance: A Novel Mobile Health System to Support Trunk Endurance Assessment

by Oresti Banos^1,*, Jose Antonio Moral-Munoz², Ignacio Diaz-Reyes³, Manuel Arroyo-Morales⁴, Miguel Damas³

, Enrique Herrera-Viedma⁵, Choong Seon Hong¹, Sungyong Lee^1,*, Hector Pomares³, Ignacio Rojas^3,* and Claudia Villalonga³

¹ Department of Computer Engineering, Kyung Hee University, Yongin-si 446-701, Korea

² Department of Library Science, University of Granada, Granada E18071, Spain

³ Department of Computer Architecture and Computer Technology, CITIC-UGR (Research Center on Information and Communications Technology), University of Granada, Granada E18071, Spain

⁴ Department of Physical Therapy, University of Granada, Granada E18071, Spain

⁵ Department of Computer Science and Artificial Intelligence, CITIC-UGR (Research Center on Information and Communications Technology), University of Granada, Granada E18071, Spain

Sensors 2015, 15(6), 13159-13183; https://doi.org/10.3390/s150613159 - 5 Jun 2015

Cited by 37 | Viewed by 11186

Abstract

Low back pain is the most prevalent musculoskeletal condition. This disorder constitutes one of the most common causes of disability worldwide, and as a result, it has a severe socioeconomic impact. Endurance tests are normally considered in low back pain rehabilitation practice to [...] Read more.

Low back pain is the most prevalent musculoskeletal condition. This disorder constitutes one of the most common causes of disability worldwide, and as a result, it has a severe socioeconomic impact. Endurance tests are normally considered in low back pain rehabilitation practice to assess the muscle status. However, traditional procedures to evaluate these tests suffer from practical limitations, which potentially lead to inaccurate diagnoses. The use of digital technologies is considered here to facilitate the task of the expert and to increase the reliability and interpretability of the endurance tests. This work presents mDurance, a novel mobile health system aimed at supporting specialists in the functional assessment of trunk endurance by using wearable and mobile devices. The system employs a wearable inertial sensor to track the patient trunk posture, while portable electromyography sensors are used to seamlessly measure the electrical activity produced by the trunk muscles. The information registered by the sensors is processed and managed by a mobile application that facilitates the expert’s normal routine, while reducing the impact of human errors and expediting the analysis of the test results. In order to show the potential of the mDurance system, a case study has been conducted. The results of this study prove the reliability of mDurance and further demonstrate that practitioners are certainly interested in the regular use of a system of this nature. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

▼ Show Figures

17 pages, 5253 KiB

Open AccessArticle

CPM Signals for Satellite Navigation in the S and C Bands

by Rui Xue, Yanbo Sun^* and Danfeng Zhao

College of Information & Communication Engineering, Harbin Engineering University, Harbin 150001, China

Sensors 2015, 15(6), 13184-13200; https://doi.org/10.3390/s150613184 - 5 Jun 2015

Cited by 39 | Viewed by 7176

Abstract

Frequency allocations in the L band suitable for global navigation satellite system (GNSS) services are getting crowded and system providers face an ever tougher job when they try to bring in new signals and services while maintaining radio frequency compatibility. With the successive [...] Read more.

Frequency allocations in the L band suitable for global navigation satellite system (GNSS) services are getting crowded and system providers face an ever tougher job when they try to bring in new signals and services while maintaining radio frequency compatibility. With the successive opening of the S and C bands to GNSS service, the multi-band combined navigation is predicted to become a key technology for future high-precision positioning navigation systems, and a single modulation scheme satisfying the requirements in each band is a promising solution for reducing user terminal complexity. A universal modulation scheme based on the continuous phase modulation (CPM) family suitable for the above bands’ demands is proposed. Moreover, this paper has put forward two specific CPM signals for the S and C bands, respectively. Then the proposed modulation schemes, together with existing candidates, are comprehensively evaluated. Simulation results show that the proposed CPM signals can not only satisfy the constraint condition of compatibility in different bands well and reduce user terminal complexity, but also provide superior performance in terms of tracking accuracy, multi-path mitigation and anti-jamming compared to other candidate modulation schemes. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

21 pages, 4317 KiB

Open AccessArticle

Highly Sensitive Multi-Channel IDC Sensor Array for Low Concentration Taste Detection

by Md. Rajibur Rahaman Khan

and Shin-Won Kang^*

School of Electronics Engineering, Kyungpook National University, 1370 Sankyuk-Dong, Bukgu, Daegu 702-701, Korea

Sensors 2015, 15(6), 13201-13221; https://doi.org/10.3390/s150613201 - 5 Jun 2015

Cited by 34 | Viewed by 11595

Abstract

In this study, we designed and developed an interdigitated capacitor (IDC)-based taste sensor array to detect different taste substances. The designed taste sensing array has four IDC sensing elements. The four IDC taste sensing elements of the array are fabricated by incorporating four [...] Read more.

In this study, we designed and developed an interdigitated capacitor (IDC)-based taste sensor array to detect different taste substances. The designed taste sensing array has four IDC sensing elements. The four IDC taste sensing elements of the array are fabricated by incorporating four different types of lipids into the polymer, dioctyl phenylphosphonate (DOPP) and tetrahydrofuran (THF) to make the respective dielectric materials that are individually placed onto an interdigitated electrode (IDE) via spin coating. When the dielectric material of an IDC sensing element comes into contact with a taste substance, its dielectric properties change with the capacitance of the IDC sensing element; this, in turn, changes the voltage across the IDC, as well as the output voltage of each channel of the system. In order to assess the effectiveness of the sensing system, four taste substances, namely sourness (HCl), saltiness (NaCl), sweetness (glucose) and bitterness (quinine-HCl), were tested. The IDC taste sensor array had rapid response and recovery times of about 12.9 s and 13.39 s, respectively, with highly stable response properties. The response property of the proposed IDC taste sensor array was linear, and its correlation coefficient R² was about 0.9958 over the dynamic range of the taste sensor array as the taste substance concentration was varied from 1 μM to 1 M. The proposed IDC taste sensor array has several other advantages, such as real-time monitoring capabilities, high sensitivity 45.78 mV/decade, good reproducibility with a standard deviation of about 0.029 and compactness, and the circuitry is based on readily available and inexpensive electronic components. The proposed IDC taste sensor array was compared with the potentiometric taste sensor with respect to sensitivity, dynamic range width, linearity and response time. We found that the proposed IDC sensor array has better performance. Finally, principal component analysis (PCA) was applied to discriminate different types of taste of the mixed taste substances. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

Figure 1

20 pages, 1980 KiB

Open AccessArticle

Region-Based Collision Avoidance Beaconless Geographic Routing Protocol in Wireless Sensor Networks

by JeongCheol Lee¹, HoSung Park², SeokYoon Kang² and Ki-Il Kim^2,*

¹ Department of Computer Science, University of California, Los Angeles, CA 90095, USA

² Department of Informatics, Research Center for Aerospace Parts Technology, Gyeongsang National University, Jinju 660-701, Korea

Sensors 2015, 15(6), 13222-13241; https://doi.org/10.3390/s150613222 - 5 Jun 2015

Cited by 14 | Viewed by 5222

Abstract

Due to the lack of dependency on beacon messages for location exchange, the beaconless geographic routing protocol has attracted considerable attention from the research community. However, existing beaconless geographic routing protocols are likely to generate duplicated data packets when multiple winners in the [...] Read more.

Due to the lack of dependency on beacon messages for location exchange, the beaconless geographic routing protocol has attracted considerable attention from the research community. However, existing beaconless geographic routing protocols are likely to generate duplicated data packets when multiple winners in the greedy area are selected. Furthermore, these protocols are designed for a uniform sensor field, so they cannot be directly applied to practical irregular sensor fields with partial voids. To prevent the failure of finding a forwarding node and to remove unnecessary duplication, in this paper, we propose a region-based collision avoidance beaconless geographic routing protocol to increase forwarding opportunities for randomly-deployed sensor networks. By employing different contention priorities into the mutually-communicable nodes and the rest of the nodes in the greedy area, every neighbor node in the greedy area can be used for data forwarding without any packet duplication. Moreover, simulation results are given to demonstrate the increased packet delivery ratio and shorten end-to-end delay, rather than well-referred comparative protocols. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

16 pages, 2904 KiB

Open AccessArticle

Sensor Prototype to Evaluate the Contact Force in Measuring with Coordinate Measuring Arms

by Eduardo Cuesta^1,*, Alejandro Telenti¹, Hector Patiño¹, Daniel González-Madruga² and Susana Martínez-Pellitero²

¹ Department of Manufacturing Engineering, University of Oviedo, Campus de Gijón, Asturias 33203, Spain

² Department of Mechanical, Informatics and Aeroespatiale Engineering, University of León, Campus de Vegazana, León 24071, Spain

Sensors 2015, 15(6), 13242-13257; https://doi.org/10.3390/s150613242 - 5 Jun 2015

Cited by 14 | Viewed by 6631

Abstract

This paper describes the design, development and evaluation tests of an integrated force sensor prototype for portable Coordinate Measuring Arms (CMAs or AACMMs). The development is based on the use of strain gauges located on the surface of the CMAs’ hard probe. The [...] Read more.

This paper describes the design, development and evaluation tests of an integrated force sensor prototype for portable Coordinate Measuring Arms (CMAs or AACMMs). The development is based on the use of strain gauges located on the surface of the CMAs’ hard probe. The strain gauges as well as their cables and connectors have been protected with a custom case, made by Additive Manufacturing techniques (Polyjet 3D). The same method has been selected to manufacture an ergonomic handle that includes trigger mechanics and the electronic components required for synchronizing the trigger signal when probing occurs. The paper also describes the monitoring software that reads the signals in real time, the calibration procedure of the prototype and the validation tests oriented towards increasing knowledge of the forces employed in manual probing. Several experiments read and record the force in real time comparing different ways of probing (discontinuous and continuous contact) and measuring different types of geometric features, from single planes to exterior cylinders, cones, or spheres, through interior features. The probing force is separated into two components allowing the influence of these strategies in probe deformation to be known. The final goal of this research is to improve the probing technique, for example by using an operator training programme, allowing extra-force peaks and bad contacts to be minimized or just to avoid bad measurements. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

12 pages, 1434 KiB

Open AccessArticle

A Flight Test of the Strapdown Airborne Gravimeter SGA-WZ in Greenland

by Lei Zhao^1,2, René Forsberg², Meiping Wu^1,*, Arne Vestergaard Olesen², Kaidong Zhang¹ and Juliang Cao¹

¹ College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha 410073, China

² National Space Institute, Technical University of Denmark, Copenhagen Ø 2800, Denmark

Sensors 2015, 15(6), 13258-13269; https://doi.org/10.3390/s150613258 - 5 Jun 2015

Cited by 15 | Viewed by 6274

Abstract

An airborne gravimeter is one of the most important tools for gravity data collection over large areas with mGal accuracy and a spatial resolution of several kilometers. In August 2012, a flight test was carried out to determine the feasibility and to assess [...] Read more.

An airborne gravimeter is one of the most important tools for gravity data collection over large areas with mGal accuracy and a spatial resolution of several kilometers. In August 2012, a flight test was carried out to determine the feasibility and to assess the accuracy of the new Chinese SGA-WZ strapdown airborne gravimeter in Greenland, in an area with good gravity coverage from earlier marine and airborne surveys. An overview of this new system SGA-WZ is given, including system design, sensor performance and data processing. The processing of the SGA-WZ includes a 160 s length finite impulse response filter, corresponding to a spatial resolution of 6 km. For the primary repeated line, a mean r.m.s. deviation of the differences was less than 1.5 mGal, with the error estimate confirmed from ground truth data. This implies that the SGA-WZ could meet standard geophysical survey requirements at the 1 mGal level. Full article

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

▼ Show Figures

Figure 1

18 pages, 2827 KiB

Open AccessArticle

Monocular-Vision-Based Autonomous Hovering for a Miniature Flying Ball

by Junqin Lin, Baoling Han^* and Qingsheng Luo

School of Mechanical Engineering, Beijing Institute of Technology, 5 Zhongguancun South Street, Haidian District, Beijing 100081, China

Sensors 2015, 15(6), 13270-13287; https://doi.org/10.3390/s150613270 - 5 Jun 2015

Cited by 1 | Viewed by 6322

Abstract

This paper presents a method for detecting and controlling the autonomous hovering of a miniature flying ball (MFB) based on monocular vision. A camera is employed to estimate the three-dimensional position of the vehicle relative to the ground without auxiliary sensors, such as [...] Read more.

This paper presents a method for detecting and controlling the autonomous hovering of a miniature flying ball (MFB) based on monocular vision. A camera is employed to estimate the three-dimensional position of the vehicle relative to the ground without auxiliary sensors, such as inertial measurement units (IMUs). An image of the ground captured by the camera mounted directly under the miniature flying ball is set as a reference. The position variations between the subsequent frames and the reference image are calculated by comparing their correspondence points. The Kalman filter is used to predict the position of the miniature flying ball to handle situations, such as a lost or wrong frame. Finally, a PID controller is designed, and the performance of the entire system is tested experimentally. The results show that the proposed method can keep the aircraft in a stable hover. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

▼ Show Figures

Graphical abstract

38 pages, 8289 KiB

Open AccessReview

Förster Resonance Energy Transfer between Quantum Dot Donors and Quantum Dot Acceptors

by Kenny F. Chou¹ and Allison M. Dennis^2,*

¹ Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA

² Department of Biomedical Engineering and Division of Materials Science and Engineering, Boston University, Boston, MA 02215, USA

Sensors 2015, 15(6), 13288-13325; https://doi.org/10.3390/s150613288 - 5 Jun 2015

Cited by 244 | Viewed by 24877

Abstract

Förster (or fluorescence) resonance energy transfer amongst semiconductor quantum dots (QDs) is reviewed, with particular interest in biosensing applications. The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems. The [...] Read more.

Förster (or fluorescence) resonance energy transfer amongst semiconductor quantum dots (QDs) is reviewed, with particular interest in biosensing applications. The unique optical properties of QDs provide certain advantages and also specific challenges with regards to sensor design, compared to other FRET systems. The brightness and photostability of QDs make them attractive for highly sensitive sensing and long-term, repetitive imaging applications, respectively, but the overlapping donor and acceptor excitation signals that arise when QDs serve as both the donor and acceptor lead to high background signals from direct excitation of the acceptor. The fundamentals of FRET within a nominally homogeneous QD population as well as energy transfer between two distinct colors of QDs are discussed. Examples of successful sensors are highlighted, as is cascading FRET, which can be used for solar harvesting. Full article

(This article belongs to the Special Issue FRET Biosensors)

▼ Show Figures

Graphical abstract

22 pages, 1066 KiB

Open AccessArticle

Passive Acoustic Source Localization at a Low Sampling Rate Based on a Five-Element Cross Microphone Array

by Yue Kan¹, Pengfei Wang¹, Fusheng Zha^1,*, Mantian Li¹, Wa Gao¹ and Baoyu Song²

¹ State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China

² Department of Mechanical Design, Harbin Institute of Technology, Harbin 150001, China

Sensors 2015, 15(6), 13326-13347; https://doi.org/10.3390/s150613326 - 5 Jun 2015

Cited by 15 | Viewed by 8012

Abstract

Accurate acoustic source localization at a low sampling rate (less than 10 kHz) is still a challenging problem for small portable systems, especially for a multitasking micro-embedded system. A modification of the generalized cross-correlation (GCC) method with the up-sampling (US) theory is proposed [...] Read more.

Accurate acoustic source localization at a low sampling rate (less than 10 kHz) is still a challenging problem for small portable systems, especially for a multitasking micro-embedded system. A modification of the generalized cross-correlation (GCC) method with the up-sampling (US) theory is proposed and defined as the US-GCC method, which can improve the accuracy of the time delay of arrival (TDOA) and source location at a low sampling rate. In this work, through the US operation, an input signal with a certain sampling rate can be converted into another signal with a higher frequency. Furthermore, the optimal interpolation factor for the US operation is derived according to localization computation time and the standard deviation (SD) of target location estimations. On the one hand, simulation results show that absolute errors of the source locations based on the US-GCC method with an interpolation factor of 15 are approximately from 1/15- to 1/12-times those based on the GCC method, when the initial same sampling rates of both methods are 8 kHz. On the other hand, a simple and small portable passive acoustic source localization platform composed of a five-element cross microphone array has been designed and set up in this paper. The experiments on the established platform, which accurately locates a three-dimensional (3D) near-field target at a low sampling rate demonstrate that the proposed method is workable. Full article

(This article belongs to the Special Issue Acoustic Waveguide Sensors)

▼ Show Figures

58 pages, 1947 KiB

Open AccessReview

The Survey on Near Field Communication

by Vedat Coskun^*, Busra Ozdenizci and Kerem Ok

NFC Lab-Istanbul, Department of Information Technologies, ISIK University, Istanbul 34980, Turkey

Sensors 2015, 15(6), 13348-13405; https://doi.org/10.3390/s150613348 - 5 Jun 2015

Cited by 96 | Viewed by 27225

Abstract

Near Field Communication (NFC) is an emerging short-range wireless communication technology that offers great and varied promise in services such as payment, ticketing, gaming, crowd sourcing, voting, navigation, and many others. NFC technology enables the integration of services from a wide range of [...] Read more.

Near Field Communication (NFC) is an emerging short-range wireless communication technology that offers great and varied promise in services such as payment, ticketing, gaming, crowd sourcing, voting, navigation, and many others. NFC technology enables the integration of services from a wide range of applications into one single smartphone. NFC technology has emerged recently, and consequently not much academic data are available yet, although the number of academic research studies carried out in the past two years has already surpassed the total number of the prior works combined. This paper presents the concept of NFC technology in a holistic approach from different perspectives, including hardware improvement and optimization, communication essentials and standards, applications, secure elements, privacy and security, usability analysis, and ecosystem and business issues. Further research opportunities in terms of the academic and business points of view are also explored and discussed at the end of each section. This comprehensive survey will be a valuable guide for researchers and academicians, as well as for business in the NFC technology and ecosystem. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Graphical abstract

18 pages, 5883 KiB

Open AccessArticle

A Multi-Channel Method for Retrieving Surface Temperature for High-Emissivity Surfaces from Hyperspectral Thermal Infrared Images

by Xinke Zhong¹, Jelila Labed¹, Guoqing Zhou², Kun Shao³ and Zhao-Liang Li^4,*

¹ ICube, UdS, CNRS, 300 Bld Sebastien Brant, CS10413, 67412 Illkirch, France

² Guangxi Key Laboratory of Spatial Information and Geomatics, Guilin University of Technology, Guilin 541004, China

³ School of Computer and Information, Hefei University of Technology, Hefei 230009, China

⁴ Key Laboratory of Agri-informatics, Ministry of Agriculture/Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China

Sensors 2015, 15(6), 13406-13423; https://doi.org/10.3390/s150613406 - 8 Jun 2015

Cited by 8 | Viewed by 5380

Abstract

The surface temperature (ST) of high-emissivity surfaces is an important parameter in climate systems. The empirical methods for retrieving ST for high-emissivity surfaces from hyperspectral thermal infrared (HypTIR) images require spectrally continuous channel data. This paper aims to develop a multi-channel method for [...] Read more.

The surface temperature (ST) of high-emissivity surfaces is an important parameter in climate systems. The empirical methods for retrieving ST for high-emissivity surfaces from hyperspectral thermal infrared (HypTIR) images require spectrally continuous channel data. This paper aims to develop a multi-channel method for retrieving ST for high-emissivity surfaces from space-borne HypTIR data. With an assumption of land surface emissivity (LSE) of 1, ST is proposed as a function of 10 brightness temperatures measured at the top of atmosphere by a radiometer having a spectral interval of 800–1200 cm⁻¹ and a spectral sampling frequency of 0.25 cm⁻¹. We have analyzed the sensitivity of the proposed method to spectral sampling frequency and instrumental noise, and evaluated the proposed method using satellite data. The results indicated that the parameters in the developed function are dependent on the spectral sampling frequency and that ST of high-emissivity surfaces can be accurately retrieved by the proposed method if appropriate values are used for each spectral sampling frequency. The results also showed that the accuracy of the retrieved ST is of the order of magnitude of the instrumental noise and that the root mean square error (RMSE) of the ST retrieved from satellite data is 0.43 K in comparison with the AVHRR SST product. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

35 pages, 6920 KiB

Open AccessArticle

Profiling of Current Transients in Capacitor Type Diamond Sensors

by Eugenijus Gaubas^1,*, Tomas Ceponis¹, Dovile Meskauskaite¹ and Nikolai Kazuchits²

¹ Institute of Applied Research, Vilnius University, Sauletekio av. 9-III, LT-10222 Vilnius, Lithuania

² Belarusian State University, Nezavisimosti av. 4, 220030 Minsk, Belarus

Sensors 2015, 15(6), 13424-13458; https://doi.org/10.3390/s150613424 - 8 Jun 2015

Cited by 8 | Viewed by 6689

Abstract

The operational characteristics of capacitor-type detectors based on HPHT and CVD diamond have been investigated using perpendicular and parallel injection of carrier domain regimes. Simulations of the drift-diffusion current transients have been implemented by using dynamic models based on Shockley-Ramo’s theorem, under injection [...] Read more.

The operational characteristics of capacitor-type detectors based on HPHT and CVD diamond have been investigated using perpendicular and parallel injection of carrier domain regimes. Simulations of the drift-diffusion current transients have been implemented by using dynamic models based on Shockley-Ramo’s theorem, under injection of localized surface domains and of bulk charge carriers. The bipolar drift-diffusion regimes have been analyzed for the photo-induced bulk domain (packet) of excess carriers. The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed. The screening effects ascribed to surface charge and to dynamics of extraction of the injected bulk excess carrier domain have been separated and explained. The parameters of drift mobility of the electrons μ_e = 4000 cm²/Vs and holes μ_h = 3800 cm²/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents. The coefficient of carrier ambipolar diffusion D_a = 97 cm²/s and the carrier recombination lifetime τ_R,CVD ≌ 110 ns in CVD diamond were extracted by combining analysis of the transients of the sensor current and the microwave probed photoconductivity. The carrier trapping with inherent lifetime τ_R,HPHT ≌ 2 ns prevails in HPHT diamond. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

18 pages, 1002 KiB

Open AccessArticle

Multiple Human Tracking Using Binary Infrared Sensors

by Toshiaki Miyazaki^* and Yuki Kasama

The University of Aizu, Aizuwakamatsu, Fukushima 965-8580, Japan

Sensors 2015, 15(6), 13459-13476; https://doi.org/10.3390/s150613459 - 8 Jun 2015

Cited by 22 | Viewed by 6476

Abstract

To create a context-aware environment, human locations and movement paths must be considered. In this paper, we propose an algorithm that tracks human movement paths using only binary sensed data obtained by infrared (IR) sensors attached to the ceiling of a room. Our [...] Read more.

To create a context-aware environment, human locations and movement paths must be considered. In this paper, we propose an algorithm that tracks human movement paths using only binary sensed data obtained by infrared (IR) sensors attached to the ceiling of a room. Our algorithm can estimate multiple human movement paths without a priori knowledge of the number of humans in the room. By repeating predictions and estimations of human positions and links from the previous human positions to the estimated ones at each time period, human movement paths can be estimated. Simulation-based evaluation results show that our algorithm can dynamically trace human movement paths. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2015)

▼ Show Figures

Figure 1

26 pages, 858 KiB

Open AccessArticle

Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays

by Andrea Trucco^1,2,*

, Federico Traverso¹ and Marco Crocco²

¹ Department of Electrical, Electronic, Telecommunications Engineering, and Naval Architecture (DITEN), University of Genoa, 5-16126 Genova, Italy

² Pattern Analysis & Computer Vision (PAVIS), Istituto Italiano di Tecnologia (IIT), 30.16163 Genova, Italy

Sensors 2015, 15(6), 13477-13502; https://doi.org/10.3390/s150613477 - 9 Jun 2015

Cited by 7 | Viewed by 5921

Abstract

For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary [...] Read more.

For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed). In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

19 pages, 1695 KiB

Open AccessArticle

Ratiometric Molecular Probes Based on Dual Emission of a Blue Fluorescent Coumarin and a Red Phosphorescent Cationic Iridium(III) Complex for Intracellular Oxygen Sensing

by Toshitada Yoshihara, Saori Murayama and Seiji Tobita^*

Department of Chemistry and Chemical Biology, Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan

Sensors 2015, 15(6), 13503-13521; https://doi.org/10.3390/s150613503 - 9 Jun 2015

Cited by 49 | Viewed by 8853

Abstract

Ratiometric molecular probes RP1 and RP2 consisting of a blue fluorescent coumarin and a red phosphorescent cationic iridium complex connected by a tetra- or octaproline linker, respectively, were designed and synthesized for sensing oxygen levels in living cells. These probes exhibited dual emission [...] Read more.

Ratiometric molecular probes RP1 and RP2 consisting of a blue fluorescent coumarin and a red phosphorescent cationic iridium complex connected by a tetra- or octaproline linker, respectively, were designed and synthesized for sensing oxygen levels in living cells. These probes exhibited dual emission with good spectral separation in acetonitrile. The photorelaxation processes, including intramolecular energy transfer, were revealed by emission quantum yield and lifetime measurements. The ratios (R_I = (I_p /I_f) ) between the phosphorescence (I_p) and fluorescence (I_f) intensities showed excellent oxygen responses; the ratio of R_I under degassed and aerated conditions (

R_{I}^{0}

/ R_I) was 20.3 and 19.6 for RP1 and RP2. The introduction of the cationic Ir (III) complex improved the cellular uptake efficiency compared to that of a neutral analogue with a tetraproline linker. The emission spectra of the ratiometric probes internalized into living HeLa or MCF-7 cells could be obtained using a conventional microplate reader. The complex RP2 with an octaproline linker provided ratios comparable to the ratiometric measurements obtained using a microplate reader: the ratio of the value of RP2 under hypoxia (2.5% O₂) to that under normoxia (21% O₂) was 1.5 and 1.7 for HeLa and MCF-7 cells, respectively. Thus, the intracellular oxygen levels of MCF-7 cells could be imaged by ratiometric emission measurements using the complex RP2. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2015)

▼ Show Figures

Graphical abstract

11 pages, 1178 KiB

Open AccessArticle

A Ni-Doped Carbon Nanotube Sensor for Detecting Oil-Dissolved Gases in Transformers

by Jia Lu¹, Xiaoxing Zhang^1,*

, Xiaoqing Wu¹, Ziqiang Dai² and Jinbin Zhang³

¹ State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Shapingba District, Chongqing 400044, China

² State Grid Guizhou Liupanshui Power Supply Company, Liupanshui 553000, China

³ Chongqing Power Company, Beibei 400700, China

Sensors 2015, 15(6), 13522-13532; https://doi.org/10.3390/s150613522 - 9 Jun 2015

Cited by 47 | Viewed by 7563

Abstract

C₂H₂, C₂H₄, and C₂H₆ are important oil-dissolved gases in power transformers. Detection of the composition and content of oil-dissolved gases in transformers is very significant in the diagnosis and assessment of the [...] Read more.

C₂H₂, C₂H₄, and C₂H₆ are important oil-dissolved gases in power transformers. Detection of the composition and content of oil-dissolved gases in transformers is very significant in the diagnosis and assessment of the state of transformer operations. The commonly used oil-gas analysis methods have many disadvantages, so this paper proposes a Ni-doped carbon nanotube (Ni-CNT) gas sensor to effectively detect oil-dissolved gases in a transformer. The gas-sensing properties of the sensor to C₂H₂, C₂H₄, and C₂H₆ were studied using the test device. Based on the density functional theory (DFT) the adsorption behaviors of the three gases on intrinsic carbon nanotubes (CNTs) and Ni-CNTs were calculated. The adsorption energy, charge transfer, and molecular frontier orbital of the adsorption system were also analyzed. Results showed that the sensitivity of the CNT sensor to the three kinds of gases was in the following order: C₂H₂ > C₂H₄ > C₂H₆. Moreover, the doped Ni improved the sensor response, and the sensor response and gas concentration have a good linear relationship. Full article

(This article belongs to the Special Issue Gas Sensors—Designs and Applications)

▼ Show Figures

Figure 1

15 pages, 2060 KiB

Open AccessArticle

3D Laser Triangulation for Plant Phenotyping in Challenging Environments

by Katrine Heinsvig Kjaer^* and Carl-Otto Ottosen

Department of Food Science, Aarhus University, Kirstinebjergvej 10, 5792 Aarslev, Denmark

Sensors 2015, 15(6), 13533-13547; https://doi.org/10.3390/s150613533 - 9 Jun 2015

Cited by 75 | Viewed by 12195

Abstract

To increase the understanding of how the plant phenotype is formed by genotype and environmental interactions, simple and robust high-throughput plant phenotyping methods should be developed and considered. This would not only broaden the application range of phenotyping in the plant research community, [...] Read more.

To increase the understanding of how the plant phenotype is formed by genotype and environmental interactions, simple and robust high-throughput plant phenotyping methods should be developed and considered. This would not only broaden the application range of phenotyping in the plant research community, but also increase the ability for researchers to study plants in their natural environments. By studying plants in their natural environment in high temporal resolution, more knowledge on how multiple stresses interact in defining the plant phenotype could lead to a better understanding of the interaction between plant responses and epigenetic regulation. In the present paper, we evaluate a commercial 3D NIR-laser scanner (PlantEye, Phenospex B.V., Herleen, The Netherlands) to track daily changes in plant growth with high precision in challenging environments. Firstly, we demonstrate that the NIR laser beam of the scanner does not affect plant photosynthetic performance. Secondly, we demonstrate that it is possible to estimate phenotypic variation amongst the growth pattern of ten genotypes of Brassica napus L. (rapeseed), using a simple linear correlation between scanned parameters and destructive growth measurements. Our results demonstrate the high potential of 3D laser triangulation for simple measurements of phenotypic variation in challenging environments and in a high temporal resolution. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Graphical abstract

20 pages, 2090 KiB

Open AccessArticle

Design Procedure and Fabrication of Reproducible Silicon Vernier Devices for High-Performance Refractive Index Sensing

by Benedetto Troia¹, Ali Z. Khokhar², Milos Nedeljkovic², Scott A. Reynolds², Youfang Hu², Goran Z. Mashanovich² and Vittorio M. N. Passaro^1,*

¹ Department of Electrical and Information Engineering, Politecnico di Bari, Via E. Orabona 4, 70125 Bari, Italy

² Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK

Sensors 2015, 15(6), 13548-13567; https://doi.org/10.3390/s150613548 - 10 Jun 2015

Cited by 16 | Viewed by 6871

Abstract

In this paper, we propose a generalized procedure for the design of integrated Vernier devices for high performance chemical and biochemical sensing. In particular, we demonstrate the accurate control of the most critical design and fabrication parameters of silicon-on-insulator cascade-coupled racetrack resonators operating [...] Read more.

In this paper, we propose a generalized procedure for the design of integrated Vernier devices for high performance chemical and biochemical sensing. In particular, we demonstrate the accurate control of the most critical design and fabrication parameters of silicon-on-insulator cascade-coupled racetrack resonators operating in the second regime of the Vernier effect, around 1.55 μm. The experimental implementation of our design strategies has allowed a rigorous and reliable investigation of the influence of racetrack resonator and directional coupler dimensions as well as of waveguide process variability on the operation of Vernier devices. Figures of merit of our Vernier architectures have been measured experimentally, evidencing a high reproducibility and a very good agreement with the theoretical predictions, as also confirmed by relative errors even lower than 1%. Finally, a Vernier gain as high as 30.3, average insertion loss of 2.1 dB and extinction ratio up to 30 dB have been achieved. Full article

(This article belongs to the Special Issue Silicon Based Optical Sensors)

▼ Show Figures

Figure 1

23 pages, 2071 KiB

Open AccessArticle

Discomfort Evaluation of Truck Ingress/Egress Motions Based on Biomechanical Analysis

by Nam-Chul Choi and Sang Hun Lee^*

Intelligent HMI/CAD Lab, Graduate School of Automotive Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Korea

Sensors 2015, 15(6), 13568-13590; https://doi.org/10.3390/s150613568 - 10 Jun 2015

Cited by 6 | Viewed by 8180

Abstract

This paper presents a quantitative discomfort evaluation method based on biomechanical analysis results for human body movement, as well as its application to an assessment of the discomfort for truck ingress and egress. In this study, the motions of a human subject entering [...] Read more.

This paper presents a quantitative discomfort evaluation method based on biomechanical analysis results for human body movement, as well as its application to an assessment of the discomfort for truck ingress and egress. In this study, the motions of a human subject entering and exiting truck cabins with different types, numbers, and heights of footsteps were first measured using an optical motion capture system and load sensors. Next, the maximum voluntary contraction (MVC) ratios of the muscles were calculated through a biomechanical analysis of the musculoskeletal human model for the captured motion. Finally, the objective discomfort was evaluated using the proposed discomfort model based on the MVC ratios. To validate this new discomfort assessment method, human subject experiments were performed to investigate the subjective discomfort levels through a questionnaire for comparison with the objective discomfort levels. The validation results showed that the correlation between the objective and subjective discomforts was significant and could be described by a linear regression model. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Graphical abstract

36 pages, 4627 KiB

Open AccessArticle

A Computational Architecture Based on RFID Sensors for Traceability in Smart Cities

by Higinio Mora-Mora^*

, Virgilio Gilart-Iglesias

, David Gil and Alejandro Sirvent-Llamas

Specialized Processors Architecture Laboratory, Department of Computer Science Technology and Computation, University of Alicante, 03690 Alicante, Spain

Sensors 2015, 15(6), 13591-13626; https://doi.org/10.3390/s150613591 - 10 Jun 2015

Cited by 49 | Viewed by 11380

Abstract

Information Technology and Communications (ICT) is presented as the main element in order to achieve more efficient and sustainable city resource management, while making sure that the needs of the citizens to improve their quality of life are satisfied. A key element will [...] Read more.

Information Technology and Communications (ICT) is presented as the main element in order to achieve more efficient and sustainable city resource management, while making sure that the needs of the citizens to improve their quality of life are satisfied. A key element will be the creation of new systems that allow the acquisition of context information, automatically and transparently, in order to provide it to decision support systems. In this paper, we present a novel distributed system for obtaining, representing and providing the flow and movement of people in densely populated geographical areas. In order to accomplish these tasks, we propose the design of a smart sensor network based on RFID communication technologies, reliability patterns and integration techniques. Contrary to other proposals, this system represents a comprehensive solution that permits the acquisition of user information in a transparent and reliable way in a non-controlled and heterogeneous environment. This knowledge will be useful in moving towards the design of smart cities in which decision support on transport strategies, business evaluation or initiatives in the tourism sector will be supported by real relevant information. As a final result, a case study will be presented which will allow the validation of the proposal. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

▼ Show Figures

Figure 1

17 pages, 1136 KiB

Open AccessArticle

Precise Point Positioning with Partial Ambiguity Fixing

by Pan Li and Xiaohong Zhang^*

School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

Sensors 2015, 15(6), 13627-13643; https://doi.org/10.3390/s150613627 - 10 Jun 2015

Cited by 80 | Viewed by 7409

Abstract

Reliable and rapid ambiguity resolution (AR) is the key to fast precise point positioning (PPP). We propose a modified partial ambiguity resolution (PAR) method, in which an elevation and standard deviation criterion are first used to remove the low-precision ambiguity estimates for AR. [...] Read more.

Reliable and rapid ambiguity resolution (AR) is the key to fast precise point positioning (PPP). We propose a modified partial ambiguity resolution (PAR) method, in which an elevation and standard deviation criterion are first used to remove the low-precision ambiguity estimates for AR. Subsequently the success rate and ratio-test are simultaneously used in an iterative process to increase the possibility of finding a subset of decorrelated ambiguities which can be fixed with high confidence. One can apply the proposed PAR method to try to achieve an ambiguity-fixed solution when full ambiguity resolution (FAR) fails. We validate this method using data from 450 stations during DOY 021 to 027, 2012. Results demonstrate the proposed PAR method can significantly shorten the time to first fix (TTFF) and increase the fixing rate. Compared with FAR, the average TTFF for PAR is reduced by 14.9% for static PPP and 15.1% for kinematic PPP. Besides, using the PAR method, the average fixing rate can be increased from 83.5% to 98.2% for static PPP, from 80.1% to 95.2% for kinematic PPP respectively. Kinematic PPP accuracy with PAR can also be significantly improved, compared to that with FAR, due to a higher fixing rate. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

16 pages, 1476 KiB

Open AccessArticle

Time-Domain Simulation of Along-Track Interferometric SAR for Moving Ocean Surfaces

by Takero Yoshida^1,* and Chang-Kyu Rheem²

¹ Department of Ocean Technology, Policy and Environment, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 153-8505, Japan

² Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

Sensors 2015, 15(6), 13644-13659; https://doi.org/10.3390/s150613644 - 10 Jun 2015

Cited by 11 | Viewed by 5092

Abstract

A time-domain simulation of along-track interferometric synthetic aperture radar (AT-InSAR) has been developed to support ocean observations. The simulation is in the time domain and based on Bragg scattering to be applicable for moving ocean surfaces. The time-domain simulation is suitable for examining [...] Read more.

A time-domain simulation of along-track interferometric synthetic aperture radar (AT-InSAR) has been developed to support ocean observations. The simulation is in the time domain and based on Bragg scattering to be applicable for moving ocean surfaces. The time-domain simulation is suitable for examining velocities of moving objects. The simulation obtains the time series of microwave backscattering as raw signals for movements of ocean surfaces. In terms of realizing Bragg scattering, the computational grid elements for generating the numerical ocean surface are set to be smaller than the wavelength of the Bragg resonant wave. In this paper, the simulation was conducted for a Bragg resonant wave and irregular waves with currents. As a result, the phases of the received signals from two antennas differ due to the movement of the numerical ocean surfaces. The phase differences shifted by currents were in good agreement with the theoretical values. Therefore, the adaptability of the simulation to observe velocities of ocean surfaces with AT-InSAR was confirmed. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

10 pages, 1408 KiB

Open AccessArticle

Detection Wavelength Control of Uncooled Infrared Sensors Using Two-Dimensional Lattice Plasmonic Absorbers

by Yousuke Takagawa¹, Shinpei Ogawa^2,*

and Masafumi Kimata^1,*

¹ College of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan

² Advanced Technology R&D Center, Mitsubishi Electric Corporation, 8-1-1 Tsukaguchi-Honmachi, Amagasaki, Hyogo 661-8661, Japan

Sensors 2015, 15(6), 13660-13669; https://doi.org/10.3390/s150613660 - 10 Jun 2015

Cited by 31 | Viewed by 7152

Abstract

Wavelength-selective uncooled infrared (IR) sensors are highly promising for a wide range of applications, such as fire detection, gas analysis and biomedical analysis. We have recently developed wavelength-selective uncooled IR sensors using square lattice two-dimensional plasmonic absorbers (2-D PLAs). The PLAs consist of [...] Read more.

Wavelength-selective uncooled infrared (IR) sensors are highly promising for a wide range of applications, such as fire detection, gas analysis and biomedical analysis. We have recently developed wavelength-selective uncooled IR sensors using square lattice two-dimensional plasmonic absorbers (2-D PLAs). The PLAs consist of a periodic 2-D lattice of Au-based dimples, which allow photons to be manipulated using surface plasmon modes. In the present study, a detailed investigation into control of the detection wavelength was conducted by varying the PLA lattice structure. A comparison was made between wavelength-selective uncooled IR sensors with triangular and square PLA lattices that were fabricated using complementary metal oxide semiconductor and micromachining techniques. Selective enhancement of the responsivity could be achieved, and the detection wavelength for the triangular lattice was shorter than that for the square lattice. The results indicate that the detection wavelength is determined by the reciprocal-lattice vector for the PLAs. The ability to control the detection wavelength in this manner enables the application of such PLAs to many types of thermal IR sensors. The results obtained here represent an important step towards multi-color imaging in the IR region. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2015)

▼ Show Figures

Figure 1

10 pages, 2809 KiB

Open AccessArticle

Piezoelectric Sensor to Measure Soft and Hard Stiffness with High Sensitivity for Ultrasonic Transducers

by Yan-Rui Li¹, Chih-Chung Su¹, Wen-Jin Lin¹ and Shuo-Hung Chang^1,2,*

¹ Department of Mechanical Engineering, National Taiwan University, Taipei 106, Taiwan

² Mechanical and Systems Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan

Sensors 2015, 15(6), 13670-13679; https://doi.org/10.3390/s150613670 - 11 Jun 2015

Cited by 9 | Viewed by 9800

Abstract

During dental sinus lift surgery, it is important to monitor the thickness of the remaining maxilla to avoid perforating the sinus membrane. Therefore, a sensor should be integrated into ultrasonic dental tools to prevent undesirable damage. This paper presents a piezoelectric (PZT) sensor [...] Read more.

During dental sinus lift surgery, it is important to monitor the thickness of the remaining maxilla to avoid perforating the sinus membrane. Therefore, a sensor should be integrated into ultrasonic dental tools to prevent undesirable damage. This paper presents a piezoelectric (PZT) sensor installed in an ultrasonic transducer to measure the stiffness of high and low materials. Four design types using three PZT ring materials and a split PZT for actuator and sensor ring materials were studied. Three sensor locations were also examined. The voltage signals of the sensor and the displacement of the actuator were analyzed to distinguish the low and high stiffness. Using sensor type T₁ made of the PZT-1 material and the front location A₁ provided a high sensitivity of 2.47 Vm/kN. The experimental results demonstrated that our design can measure soft and hard stiffness. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

25 pages, 14079 KiB

Open AccessReview

Modulated Raman Spectroscopy for Enhanced Cancer Diagnosis at the Cellular Level

by Anna Chiara De Luca^1,*

, Kishan Dholakia² and Michael Mazilu²

¹ Institute of Protein Biochemistry, National Research Council, Via P. Castellino, 111, 80131 Naples, Italy

² SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh KY16 9SS, St Andrews, UK

Sensors 2015, 15(6), 13680-13704; https://doi.org/10.3390/s150613680 - 11 Jun 2015

Cited by 49 | Viewed by 14052

Abstract

Raman spectroscopy is emerging as a promising and novel biophotonics tool for non-invasive, real-time diagnosis of tissue and cell abnormalities. However, the presence of a strong fluorescence background is a key issue that can detract from the use of Raman spectroscopy in routine [...] Read more.

Raman spectroscopy is emerging as a promising and novel biophotonics tool for non-invasive, real-time diagnosis of tissue and cell abnormalities. However, the presence of a strong fluorescence background is a key issue that can detract from the use of Raman spectroscopy in routine clinical care. The review summarizes the state-of-the-art methods to remove the fluorescence background and explores recent achievements to address this issue obtained with modulated Raman spectroscopy. This innovative approach can be used to extract the Raman spectral component from the fluorescence background and improve the quality of the Raman signal. We describe the potential of modulated Raman spectroscopy as a rapid, inexpensive and accurate clinical tool to detect the presence of bladder cancer cells. Finally, in a broader context, we show how this approach can greatly enhance the sensitivity of integrated Raman spectroscopy and microfluidic systems, opening new prospects for portable higher throughput Raman cell sorting. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

▼ Show Figures

20 pages, 8058 KiB

Open AccessArticle

Socially Aware Heterogeneous Wireless Networks

by Pavlos Kosmides^1,*, Evgenia Adamopoulou¹

, Konstantinos Demestichas¹, Michael Theologou¹, Miltiades Anagnostou¹ and Angelos Rouskas²

¹ School of Electrical and Computer Engineering, National Technical University of Athens, Athens 15773, Greece

² Department of Digital Systems, University of Piraeus, Piraeus 18534, Greece

Sensors 2015, 15(6), 13705-13724; https://doi.org/10.3390/s150613705 - 11 Jun 2015

Cited by 9 | Viewed by 6410

Abstract

The development of smart cities has been the epicentre of many researchers’ efforts during the past decade. One of the key requirements for smart city networks is mobility and this is the reason stable, reliable and high-quality wireless communications are needed in order [...] Read more.

The development of smart cities has been the epicentre of many researchers’ efforts during the past decade. One of the key requirements for smart city networks is mobility and this is the reason stable, reliable and high-quality wireless communications are needed in order to connect people and devices. Most research efforts so far, have used different kinds of wireless and sensor networks, making interoperability rather difficult to accomplish in smart cities. One common solution proposed in the recent literature is the use of software defined networks (SDNs), in order to enhance interoperability among the various heterogeneous wireless networks. In addition, SDNs can take advantage of the data retrieved from available sensors and use them as part of the intelligent decision making process contacted during the resource allocation procedure. In this paper, we propose an architecture combining heterogeneous wireless networks with social networks using SDNs. Specifically, we exploit the information retrieved from location based social networks regarding users’ locations and we attempt to predict areas that will be crowded by using specially-designed machine learning techniques. By recognizing possible crowded areas, we can provide mobile operators with recommendations about areas requiring datacell activation or deactivation. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

▼ Show Figures

Figure 1

27 pages, 4078 KiB

Open AccessArticle

A Cross Structured Light Sensor and Stripe Segmentation Method for Visual Tracking of a Wall Climbing Robot

by Liguo Zhang, Jianguo Sun^*, Guisheng Yin, Jing Zhao and Qilong Han

College of Computer Science and Technology, Harbin Engineering University, Harbin 150001, China

Sensors 2015, 15(6), 13725-13751; https://doi.org/10.3390/s150613725 - 11 Jun 2015

Cited by 29 | Viewed by 9582

Abstract

In non-destructive testing (NDT) of metal welds, weld line tracking is usually performed outdoors, where the structured light sources are always disturbed by various noises, such as sunlight, shadows, and reflections from the weld line surface. In this paper, we design a cross [...] Read more.

In non-destructive testing (NDT) of metal welds, weld line tracking is usually performed outdoors, where the structured light sources are always disturbed by various noises, such as sunlight, shadows, and reflections from the weld line surface. In this paper, we design a cross structured light (CSL) to detect the weld line and propose a robust laser stripe segmentation algorithm to overcome the noises in structured light images. An adaptive monochromatic space is applied to preprocess the image with ambient noises. In the monochromatic image, the laser stripe obtained is recovered as a multichannel signal by minimum entropy deconvolution. Lastly, the stripe centre points are extracted from the image. In experiments, the CSL sensor and the proposed algorithm are applied to guide a wall climbing robot inspecting the weld line of a wind power tower. The experimental results show that the CSL sensor can capture the 3D information of the welds with high accuracy, and the proposed algorithm contributes to the weld line inspection and the robot navigation. Full article

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

▼ Show Figures

Figure 1

11 pages, 983 KiB

Open AccessArticle

Photography by Cameras Integrated in Smartphones as a Tool for Analytical Chemistry Represented by an Butyrylcholinesterase Activity Assay

by Miroslav Pohanka

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

Sensors 2015, 15(6), 13752-13762; https://doi.org/10.3390/s150613752 - 11 Jun 2015

Cited by 35 | Viewed by 6215

Abstract

Smartphones are popular devices frequently equipped with sensitive sensors and great computational ability. Despite the widespread availability of smartphones, practical uses in analytical chemistry are limited, though some papers have proposed promising applications. In the present paper, a smartphone is used as a [...] Read more.

Smartphones are popular devices frequently equipped with sensitive sensors and great computational ability. Despite the widespread availability of smartphones, practical uses in analytical chemistry are limited, though some papers have proposed promising applications. In the present paper, a smartphone is used as a tool for the determination of cholinesterasemia i.e., the determination of a biochemical marker butyrylcholinesterase (BChE). The work should demonstrate suitability of a smartphone-integrated camera for analytical purposes. Paper strips soaked with indoxylacetate were used for the determination of BChE activity, while the standard Ellman’s assay was used as a reference measurement. In the smartphone-based assay, BChE converted indoxylacetate to indigo blue and coloration was photographed using the phone’s integrated camera. A RGB color model was analyzed and color values for the individual color channels were determined. The assay was verified using plasma samples and samples containing pure BChE, and validated using Ellmans’s assay. The smartphone assay was proved to be reliable and applicable for routine diagnoses where BChE serves as a marker (liver function tests; some poisonings, etc.). It can be concluded that the assay is expected to be of practical applicability because of the results’ relevance. Full article

(This article belongs to the Section Biosensors)

▼ Show Figures

Figure 1

15 pages, 2436 KiB

Open AccessArticle

Classification of Potential Water Bodies Using Landsat 8 OLI and a Combination of Two Boosted Random Forest Classifiers

by Byoung Chul Ko^*

, Hyeong Hun Kim^† and Jae Yeal Nam^†

¹ Department of Computer Engineering, Keimyung University, Sindang-dong, Dalseo-gu, Daegu 704-701, Korea

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 13763-13777; https://doi.org/10.3390/s150613763 - 11 Jun 2015

Cited by 136 | Viewed by 9134

Abstract

This study proposes a new water body classification method using top-of-atmosphere (TOA) reflectance and water indices (WIs) of the Landsat 8 Operational Land Imager (OLI) sensor and its corresponding random forest classifiers. In this study, multispectral images from the OLI sensor are represented [...] Read more.

This study proposes a new water body classification method using top-of-atmosphere (TOA) reflectance and water indices (WIs) of the Landsat 8 Operational Land Imager (OLI) sensor and its corresponding random forest classifiers. In this study, multispectral images from the OLI sensor are represented as TOA reflectance and WI values because a classification result using two measures is better than raw spectral images. Two types of boosted random forest (BRF) classifiers are learned using TOA reflectance and WI values, respectively, instead of the heuristic threshold or unsupervised methods. The final probability is summed linearly using the probabilities of two different BRFs to classify image pixels to water class. This study first demonstrates that the Landsat 8 OLI sensor has higher classification rate because it provides improved signal-to-ratio radiometric by using 12-bit quantization of the data instead of 8-bit as available from other sensors. In addition, we prove that the performance of the proposed combination of two BRF classifiers shows robust water body classification results, regardless of topology, river properties, and background environment. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

Figure 1

27 pages, 1181 KiB

Open AccessArticle

Solving Energy-Aware Real-Time Tasks Scheduling Problem with Shuffled Frog Leaping Algorithm on Heterogeneous Platforms

by Weizhe Zhang^1,*, Enci Bai¹, Hui He¹ and Albert M.K. Cheng²

¹ School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001, China

² Department of Computer Science, University of Houston, Houston, TX 77004, USA

Sensors 2015, 15(6), 13778-13804; https://doi.org/10.3390/s150613778 - 11 Jun 2015

Cited by 29 | Viewed by 6964

Abstract

Reducing energy consumption is becoming very important in order to keep battery life and lower overall operational costs for heterogeneous real-time multiprocessor systems. In this paper, we first formulate this as a combinatorial optimization problem. Then, a successful meta-heuristic, called Shuffled Frog Leaping [...] Read more.

Reducing energy consumption is becoming very important in order to keep battery life and lower overall operational costs for heterogeneous real-time multiprocessor systems. In this paper, we first formulate this as a combinatorial optimization problem. Then, a successful meta-heuristic, called Shuffled Frog Leaping Algorithm (SFLA) is proposed to reduce the energy consumption. Precocity remission and local optimal avoidance techniques are proposed to avoid the precocity and improve the solution quality. Convergence acceleration significantly reduces the search time. Experimental results show that the SFLA-based energy-aware meta-heuristic uses 30% less energy than the Ant Colony Optimization (ACO) algorithm, and 60% less energy than the Genetic Algorithm (GA) algorithm. Remarkably, the running time of the SFLA-based meta-heuristic is 20 and 200 times less than ACO and GA, respectively, for finding the optimal solution. Full article

(This article belongs to the Special Issue Cyber-Physical Systems)

▼ Show Figures

Figure 1

34 pages, 1057 KiB

Open AccessReview

Interference Mitigation Schemes for Wireless Body Area Sensor Networks: A Comparative Survey

by Thien T.T. Le and Sangman Moh^*

Department of Computer Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 501-759, Korea

Sensors 2015, 15(6), 13805-13838; https://doi.org/10.3390/s150613805 - 11 Jun 2015

Cited by 43 | Viewed by 6830

Abstract

A wireless body area sensor network (WBASN) consists of a coordinator and multiple sensors to monitor the biological signals and functions of the human body. This exciting area has motivated new research and standardization processes, especially in the area of WBASN performance and [...] Read more.

A wireless body area sensor network (WBASN) consists of a coordinator and multiple sensors to monitor the biological signals and functions of the human body. This exciting area has motivated new research and standardization processes, especially in the area of WBASN performance and reliability. In scenarios of mobility or overlapped WBASNs, system performance will be significantly degraded because of unstable signal integrity. Hence, it is necessary to consider interference mitigation in the design. This survey presents a comparative review of interference mitigation schemes in WBASNs. Further, we show that current solutions are limited in reaching satisfactory performance, and thus, more advanced solutions should be developed in the future. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

12 pages, 546 KiB

Open AccessArticle

A Microfluidic Love-Wave Biosensing Device for PSA Detection Based on an Aptamer Beacon Probe

by Feng Zhang¹, Shuangming Li¹, Kang Cao¹, Pengjuan Wang², Yan Su¹, Xinhua Zhu^1,* and Ying Wan^1,*

¹ School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

² School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

Sensors 2015, 15(6), 13839-13850; https://doi.org/10.3390/s150613839 - 11 Jun 2015

Cited by 52 | Viewed by 9097

Abstract

A label-free and selective aptamer beacon-based Love-wave biosensing device was developed for prostate specific antigen (PSA) detection. The device consists of the following parts: LiTaO₃ substrate with SiO₂ film as wave guide layer, two set of inter-digital transducers (IDT), gold film [...] Read more.

A label-free and selective aptamer beacon-based Love-wave biosensing device was developed for prostate specific antigen (PSA) detection. The device consists of the following parts: LiTaO₃ substrate with SiO₂ film as wave guide layer, two set of inter-digital transducers (IDT), gold film for immobilization of the biorecongniton layer and a polydimethylsiloxane (PDMS) microfluidic channels. DNA aptamer, or “artificial antibody”, was used as the specific biorecognition probe for PSA capture. Some nucleotides were added to the 3'-end of the aptamer to form a duplex with the 3'-end, turning the aptamer into an aptamer-beacon. Taking advantage of the selective target-induced assembly changes arising from the “aptamer beacon”, highly selective and specific detection of PSA was achieved. Furthermore, PDMS microfluidic channels were designed and fabricated to realize automated quantitative sample injection. After optimization of the experimental conditions, the established device showed good performance for PSA detection between 10 ng/mL to 1 μg/mL, with a detection limit of 10 ng/mL. The proposed sensor might be a promising alternative for point of care diagnostics. Full article

(This article belongs to the Special Issue On-Chip Sensors)

▼ Show Figures

Graphical abstract

23 pages, 2126 KiB

Open AccessArticle

An Evaluation of the Pedestrian Classification in a Multi-Domain Multi-Modality Setup

by Alina Miron^1,*, Alexandrina Rogozan², Samia Ainouz², Abdelaziz Bensrhair² and Alberto Broggi³

¹ ISR Laboratory, University of Reading, Reading RG6 6AY, UK

² INSA Rouen/LITIS laboratory - EA4108, Saint-Etienne du Rouvray 76801, France

³ VisLab, University of Parma, Parco Area delle Scienze 181A, 43100 Parma, Italy

Sensors 2015, 15(6), 13851-13873; https://doi.org/10.3390/s150613851 - 12 Jun 2015

Cited by 18 | Viewed by 6748

Abstract

The objective of this article is to study the problem of pedestrian classification across different light spectrum domains (visible and far-infrared (FIR)) and modalities (intensity, depth and motion). In recent years, there has been a number of approaches for classifying and detecting pedestrians [...] Read more.

The objective of this article is to study the problem of pedestrian classification across different light spectrum domains (visible and far-infrared (FIR)) and modalities (intensity, depth and motion). In recent years, there has been a number of approaches for classifying and detecting pedestrians in both FIR and visible images, but the methods are difficult to compare, because either the datasets are not publicly available or they do not offer a comparison between the two domains. Our two primary contributions are the following: (1) we propose a public dataset, named RIFIR , containing both FIR and visible images collected in an urban environment from a moving vehicle during daytime; and (2) we compare the state-of-the-art features in a multi-modality setup: intensity, depth and flow, in far-infrared over visible domains. The experiments show that features families, intensity self-similarity (ISS), local binary patterns (LBP), local gradient patterns (LGP) and histogram of oriented gradients (HOG), computed from FIR and visible domains are highly complementary, but their relative performance varies across different modalities. In our experiments, the FIR domain has proven superior to the visible one for the task of pedestrian classification, but the overall best results are obtained by a multi-domain multi-modality multi-feature fusion. Full article

(This article belongs to the Special Issue Frontiers in Infrared Photodetection)

▼ Show Figures

25 pages, 1349 KiB

Open AccessArticle

A Space-Time Network-Based Modeling Framework for Dynamic Unmanned Aerial Vehicle Routing in Traffic Incident Monitoring Applications

by Jisheng Zhang^1,2, Limin Jia³, Shuyun Niu², Fan Zhang², Lu Tong⁴ and Xuesong Zhou^5,*

¹ School of Traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China

² Research Institute of Highway Ministry of Transport, No. 8 Xitucheng Rd., Haidian District, Beijing 100088, China

³ State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, No. 3 Shangyuancun, Haidian District, Beijing 100044, China

⁴ School of Traffic and Transportation, Beijing Jiaotong University, No. 3 Shangyuancun, Haidian District, Beijing 100044, China

⁵ School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ 85287, USA

Sensors 2015, 15(6), 13874-13898; https://doi.org/10.3390/s150613874 - 12 Jun 2015

Cited by 33 | Viewed by 8714

Abstract

It is essential for transportation management centers to equip and manage a network of fixed and mobile sensors in order to quickly detect traffic incidents and further monitor the related impact areas, especially for high-impact accidents with dramatic traffic congestion propagation. As emerging [...] Read more.

It is essential for transportation management centers to equip and manage a network of fixed and mobile sensors in order to quickly detect traffic incidents and further monitor the related impact areas, especially for high-impact accidents with dramatic traffic congestion propagation. As emerging small Unmanned Aerial Vehicles (UAVs) start to have a more flexible regulation environment, it is critically important to fully explore the potential for of using UAVs for monitoring recurring and non-recurring traffic conditions and special events on transportation networks. This paper presents a space-time network- based modeling framework for integrated fixed and mobile sensor networks, in order to provide a rapid and systematic road traffic monitoring mechanism. By constructing a discretized space-time network to characterize not only the speed for UAVs but also the time-sensitive impact areas of traffic congestion, we formulate the problem as a linear integer programming model to minimize the detection delay cost and operational cost, subject to feasible flying route constraints. A Lagrangian relaxation solution framework is developed to decompose the original complex problem into a series of computationally efficient time-dependent and least cost path finding sub-problems. Several examples are used to demonstrate the results of proposed models in UAVs’ route planning for small and medium-scale networks. Full article

(This article belongs to the Special Issue UAV Sensors for Environmental Monitoring)

▼ Show Figures

Figure 1

18 pages, 310 KiB

Open AccessArticle

Spatial Signature Estimation with an Uncalibrated Uniform Linear Array

by Xiang Cao¹, Jingmin Xin¹, Yoshifumi Nishio^2,* and Nanning Zheng¹

¹ Institute of Artificial Intelligence and Robotics, Xi'an Jiaotong University, Xi'an 710049, China

² Department of Electrical and Electronic Engineering, Tokushima University, Tokushima 770-8506, Japan

Sensors 2015, 15(6), 13899-13915; https://doi.org/10.3390/s150613899 - 12 Jun 2015

Cited by 4 | Viewed by 5085

Abstract

In this paper, the problem of spatial signature estimation using a uniform linear array (ULA) with unknown sensor gain and phase errors is considered. As is well known, the directions-of-arrival (DOAs) can only be determined within an unknown rotational angle in this array [...] Read more.

In this paper, the problem of spatial signature estimation using a uniform linear array (ULA) with unknown sensor gain and phase errors is considered. As is well known, the directions-of-arrival (DOAs) can only be determined within an unknown rotational angle in this array model. However, the phase ambiguity has no impact on the identification of the spatial signature. Two auto-calibration methods are presented for spatial signature estimation. In our methods, the rotational DOAs and model error parameters are firstly obtained, and the spatial signature is subsequently calculated. The first method extracts two subarrays from the ULA to construct an estimator, and the elements of the array can be used several times in one subarray. The other fully exploits multiple invariances in the interior of the sensor array, and a multidimensional nonlinear problem is formulated. A Gauss–Newton iterative algorithm is applied for solving it. The first method can provide excellent initial inputs for the second one. The effectiveness of the proposed algorithms is demonstrated by several simulation results. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

29 pages, 3992 KiB

Open AccessArticle

Human-Automation Interaction Design for Adaptive Cruise Control Systems of Ground Vehicles

by Hwisoo Eom and Sang Hun Lee^*

Intelligent HMI/CAD Lab, Graduate School of Automotive Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Korea

Sensors 2015, 15(6), 13916-13944; https://doi.org/10.3390/s150613916 - 12 Jun 2015

Cited by 23 | Viewed by 13540

Abstract

A majority of recently developed advanced vehicles have been equipped with various automated driver assistance systems, such as adaptive cruise control (ACC) and lane keeping assistance systems. ACC systems have several operational modes, and drivers can be unaware of the mode in which [...] Read more.

A majority of recently developed advanced vehicles have been equipped with various automated driver assistance systems, such as adaptive cruise control (ACC) and lane keeping assistance systems. ACC systems have several operational modes, and drivers can be unaware of the mode in which they are operating. Because mode confusion is a significant human error factor that contributes to traffic accidents, it is necessary to develop user interfaces for ACC systems that can reduce mode confusion. To meet this requirement, this paper presents a new human-automation interaction design methodology in which the compatibility of the machine and interface models is determined using the proposed criteria, and if the models are incompatible, one or both of the models is/are modified to make them compatible. To investigate the effectiveness of our methodology, we designed two new interfaces by separately modifying the machine model and the interface model and then performed driver-in-the-loop experiments. The results showed that modifying the machine model provides a more compact, acceptable, effective, and safe interface than modifying the interface model. Full article

(This article belongs to the Special Issue Sensors in New Road Vehicles)

▼ Show Figures

Graphical abstract

21 pages, 5834 KiB

Open AccessArticle

Guaranteeing Isochronous Control of Networked Motion Control Systems Using Phase Offset Adjustment

by Ikhwan Kim and Taehyoun Kim^*

Department of Mechanical and Information Engineering, University of Seoul, 163 Seoulsiripdae-ro, Dongdaemun-gu, Seoul 130-743, Korea

Sensors 2015, 15(6), 13945-13965; https://doi.org/10.3390/s150613945 - 12 Jun 2015

Cited by 13 | Viewed by 6411

Abstract

Guaranteeing isochronous transfer of control commands is an essential function for networked motion control systems. The adoption of real-time Ethernet (RTE) technologies may be profitable in guaranteeing deterministic transfer of control messages. However, unpredictable behavior of software in the motion controller often results [...] Read more.

Guaranteeing isochronous transfer of control commands is an essential function for networked motion control systems. The adoption of real-time Ethernet (RTE) technologies may be profitable in guaranteeing deterministic transfer of control messages. However, unpredictable behavior of software in the motion controller often results in unexpectedly large deviation in control message transmission intervals, and thus leads to imprecise motion. This paper presents a simple and efficient heuristic to guarantee the end-to-end isochronous control with very small jitter. The key idea of our approach is to adjust the phase offset of control message transmission time in the motion controller by investigating the behavior of motion control task. In realizing the idea, we performed a pre-runtime analysis to determine a safe and reliable phase offset and applied the phase offset to the runtime code of motion controller by customizing an open-source based integrated development environment (IDE). We also constructed an EtherCAT-based motion control system testbed and performed extensive experiments on the testbed to verify the effectiveness of our approach. The experimental results show that our heuristic is highly effective even for low-end embedded controller implemented in open-source software components under various configurations of control period and the number of motor drives. Full article

(This article belongs to the Special Issue Cyber-Physical Systems)

▼ Show Figures

28 pages, 498 KiB

Open AccessArticle

Novel Spectrum Sensing Algorithms for OFDM Cognitive Radio Networks

by Zhenguo Shi¹, Zhilu Wu^1,*, Zhendong Yin¹ and Qingqing Cheng^1,2

¹ School of Electronics and Information Engineering, Harbin Institute of Technology, 92 Xidazhi Street, Harbin150001, China

² Department of engineering, Faculty of Science and Engineering, Macquarie University, North Ryde, Sydeny, NSW 2109, Australia

Sensors 2015, 15(6), 13966-13993; https://doi.org/10.3390/s150613966 - 15 Jun 2015

Cited by 8 | Viewed by 5577

Abstract

Spectrum sensing technology plays an increasingly important role in cognitive radio networks. Consequently, several spectrum sensing algorithms have been proposed in the literature. In this paper, we present a new spectrum sensing algorithm “Differential Characteristics-Based OFDM (DC-OFDM)” for detecting OFDM signal on account [...] Read more.

Spectrum sensing technology plays an increasingly important role in cognitive radio networks. Consequently, several spectrum sensing algorithms have been proposed in the literature. In this paper, we present a new spectrum sensing algorithm “Differential Characteristics-Based OFDM (DC-OFDM)” for detecting OFDM signal on account of differential characteristics. We put the primary value on channel gain Ɵ around zero to detect the presence of primary user. Furthermore, utilizing the same method of differential operation, we improve two traditional OFDM sensing algorithms (cyclic prefix and pilot tones detecting algorithms), and propose a “Differential Characteristics-Based Cyclic Prefix (DC-CP)” detector and a “Differential Characteristics-Based Pilot Tones (DC-PT)” detector, respectively. DC-CP detector is based on auto-correlation vector to sense the spectrum, while the DC-PT detector takes the frequency-domain cross-correlation of PT as the test statistic to detect the primary user. Moreover, the distributions of the test statistics of the three proposed methods have been derived. Simulation results illustrate that all of the three proposed methods can achieve good performance under low signal to noise ratio (SNR) with the presence of timing delay. Specifically, the DC-OFDM detector gets the best performance among the presented detectors. Moreover, both of the DC-CP and DC-PT detector achieve significant improvements compared with their corresponding original detectors. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

22 pages, 14298 KiB

Open AccessArticle

VIS-NIR, SWIR and LWIR Imagery for Estimation of Ground Bearing Capacity

by Roemi Fernández^1,*

, Héctor Montes^1,2 and Carlota Salinas¹

¹ Centre for Automation and Robotics (CAR) CSIC-UPM, Ctra. Campo Real, Km. 0.2, La Poveda, Arganda del Rey, Madrid 28500, Spain

² Faculty of Electrical Engineering, Technological University of Panama, Panama City 0819, Panama

Sensors 2015, 15(6), 13994-14015; https://doi.org/10.3390/s150613994 - 15 Jun 2015

Cited by 17 | Viewed by 12952

Abstract

Ground bearing capacity has become a relevant concept for site-specific management that aims to protect soil from the compaction and the rutting produced by the indiscriminate use of agricultural and forestry machines. Nevertheless, commonly known techniques for its estimation are cumbersome and time-consuming. [...] Read more.

Ground bearing capacity has become a relevant concept for site-specific management that aims to protect soil from the compaction and the rutting produced by the indiscriminate use of agricultural and forestry machines. Nevertheless, commonly known techniques for its estimation are cumbersome and time-consuming. In order to alleviate these difficulties, this paper introduces an innovative sensory system based on Visible-Near InfraRed (VIS-NIR), Short-Wave InfraRed (SWIR) and Long-Wave InfraRed (LWIR) imagery and a sequential algorithm that combines a registration procedure, a multi-class SVM classifier, a K-means clustering and a linear regression for estimating the ground bearing capacity. To evaluate the feasibility and capabilities of the presented approach, several experimental tests were carried out in a sandy-loam terrain. The proposed solution offers notable benefits such as its non-invasiveness to the soil, its spatial coverage without the need for exhaustive manual measurements and its real time operation. Therefore, it can be very useful in decision making processes that tend to reduce ground damage during agricultural and forestry operations. Full article

(This article belongs to the Special Issue Agriculture and Forestry: Sensors, Technologies and Procedures)

▼ Show Figures

Figure 1

29 pages, 940 KiB

Open AccessArticle

On Designing Thermal-Aware Localized QoS Routing Protocol for in-vivo Sensor Nodes in Wireless Body Area Networks

by Muhammad Mostafa Monowar^*

and Fuad Bajaber

Department of Information Technology, Faculty of Computing and Information Technology, King Abdul Aziz University, Jeddah-21589, Saudi Arabia

Sensors 2015, 15(6), 14016-14044; https://doi.org/10.3390/s150614016 - 15 Jun 2015

Cited by 43 | Viewed by 5748

Abstract

In this paper, we address the thermal rise and Quality-of-Service (QoS) provisioning issue for an intra-body Wireless Body Area Network (WBAN) having in-vivo sensor nodes. We propose a thermal-aware QoS routing protocol, called TLQoS, that facilitates the system in achieving desired QoS in [...] Read more.

In this paper, we address the thermal rise and Quality-of-Service (QoS) provisioning issue for an intra-body Wireless Body Area Network (WBAN) having in-vivo sensor nodes. We propose a thermal-aware QoS routing protocol, called TLQoS, that facilitates the system in achieving desired QoS in terms of delay and reliability for diverse traffic types, as well as avoids the formation of highly heated nodes known as hotspot(s), and keeps the temperature rise along the network to an acceptable level. TLQoS exploits modular architecture wherein different modules perform integrated operations in providing multiple QoS service with lower temperature rise. To address the challenges of highly dynamic wireless environment inside the human body. TLQoS implements potential-based localized routing that requires only local neighborhood information. TLQoS avoids routing loop formation as well as reduces the number of hop traversal exploiting hybrid potential, and tuning a configurable parameter. We perform extensive simulations of TLQoS, and the results show that TLQoS has significant performance improvements over state-of-the-art approaches. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

34 pages, 1916 KiB

Open AccessReview

A Review of Membrane-Based Biosensors for Pathogen Detection

by Remko Van den Hurk and Stephane Evoy^*

Department of Electrical and Computer Engineering, University of Alberta Edmonton, Alberta, AB T6G 2V4, Canada

Sensors 2015, 15(6), 14045-14078; https://doi.org/10.3390/s150614045 - 15 Jun 2015

Cited by 61 | Viewed by 17063

Abstract

Biosensors are of increasing interest for the detection of bacterial pathogens in many applications such as human, animal and plant health, as well as food and water safety. Membranes and membrane-like structures have been integral part of several pathogen detection platforms. Such structures [...] Read more.

Biosensors are of increasing interest for the detection of bacterial pathogens in many applications such as human, animal and plant health, as well as food and water safety. Membranes and membrane-like structures have been integral part of several pathogen detection platforms. Such structures may serve as simple mechanical support, function as a part of the transduction mechanism, may be used to filter out or concentrate pathogens, and may be engineered to specifically house active proteins. This review focuses on membrane materials, their associated biosensing applications, chemical linking procedures, and transduction mechanisms. The sensitivity of membrane biosensors is discussed, and the state of the field is evaluated and summarized. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

▼ Show Figures

Figure 1

14 pages, 2670 KiB

Open AccessArticle

Estimation of Prestress Force Distribution in the Multi-Strand System of Prestressed Concrete Structures

by Keunhee Cho^†

, Sung Yong Park^†, Jeong-Rae Cho^†, Sung Tae Kim^† and Young-Hwan Park^*

¹ Structural Engineering Research Institute, Korea Institute of Civil Engineering and Building Technology, 283 Goyangdae-Ro, Ilsanseo-Gu, Goyang-Si, Gyeonggi-Do 411-712, Korea

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 14079-14092; https://doi.org/10.3390/s150614079 - 15 Jun 2015

Cited by 19 | Viewed by 6748

Abstract

Prestressed concrete (PSC) is one of the most reliable, durable and widely used construction materials, which overcomes the weakness of concrete in tension by the introduction of a prestress force. Smart strands enabling measurement of the prestress force have recently been developed to [...] Read more.

Prestressed concrete (PSC) is one of the most reliable, durable and widely used construction materials, which overcomes the weakness of concrete in tension by the introduction of a prestress force. Smart strands enabling measurement of the prestress force have recently been developed to maintain PSC structures throughout their lifetime. However, the smart strand cannot give a representative indication of the whole prestress force when used in multi-strand systems since each strand sustains a different prestress force. In this paper, the actual distribution of the prestress force in a multi-strand system is examined using elastomagnetic (EM) sensors to develop a method for tracking representative indicators of the prestress force using smart strands. Full article

(This article belongs to the Special Issue Optical Sensors for Chemical, Biological and Industrial Applications)

▼ Show Figures

Figure 1

23 pages, 10031 KiB

Open AccessArticle

A High Performance Banknote Recognition System Based on a One-Dimensional Visible Light Line Sensor

by Young Ho Park¹, Seung Yong Kwon¹, Tuyen Danh Pham¹, Kang Ryoung Park^1,*, Dae Sik Jeong¹ and Sungsoo Yoon²

¹ Division of Electronics and Electrical Engineering, Dongguk University, 26 Pil-dong 3-ga, Jung-gu, Seoul 100-715, Korea

² Kisan Electronics, Sungsoo 2-ga 3-dong, Sungdong-gu, Seoul 133-831, Korea

Sensors 2015, 15(6), 14093-14115; https://doi.org/10.3390/s150614093 - 15 Jun 2015

Cited by 17 | Viewed by 6212

Abstract

An algorithm for recognizing banknotes is required in many fields, such as banknote-counting machines and automatic teller machines (ATM). Due to the size and cost limitations of banknote-counting machines and ATMs, the banknote image is usually captured by a one-dimensional (line) sensor instead [...] Read more.

An algorithm for recognizing banknotes is required in many fields, such as banknote-counting machines and automatic teller machines (ATM). Due to the size and cost limitations of banknote-counting machines and ATMs, the banknote image is usually captured by a one-dimensional (line) sensor instead of a conventional two-dimensional (area) sensor. Because the banknote image is captured by the line sensor while it is moved at fast speed through the rollers inside the banknote-counting machine or ATM, misalignment, geometric distortion, and non-uniform illumination of the captured images frequently occur, which degrades the banknote recognition accuracy. To overcome these problems, we propose a new method for recognizing banknotes. The experimental results using two-fold cross-validation for 61,240 United States dollar (USD) images show that the pre-classification error rate is 0%, and the average error rate for the final recognition of the USD banknotes is 0.114%. Full article

(This article belongs to the Special Issue Imaging: Sensors and Technologies)

▼ Show Figures

Figure 1

26 pages, 1200 KiB

Open AccessArticle

Analysis of Intelligent Transportation Systems Using Model-Driven Simulations

by Alberto Fernández-Isabel and Rubén Fuentes-Fernández^*

Departamento de Ingeniería del Software e Inteligencia Artificial, Facultad de Informática, Universidad Complutense de Madrid, 28040 Madrid, Spain

Sensors 2015, 15(6), 14116-14141; https://doi.org/10.3390/s150614116 - 15 Jun 2015

Cited by 32 | Viewed by 9388

Abstract

Intelligent Transportation Systems (ITSs) integrate information, sensor, control, and communication technologies to provide transport related services. Their users range from everyday commuters to policy makers and urban planners. Given the complexity of these systems and their environment, their study in real settings is [...] Read more.

Intelligent Transportation Systems (ITSs) integrate information, sensor, control, and communication technologies to provide transport related services. Their users range from everyday commuters to policy makers and urban planners. Given the complexity of these systems and their environment, their study in real settings is frequently unfeasible. Simulations help to address this problem, but present their own issues: there can be unintended mistakes in the transition from models to code; their platforms frequently bias modeling; and it is difficult to compare works that use different models and tools. In order to overcome these problems, this paper proposes a framework for a model-driven development of these simulations. It is based on a specific modeling language that supports the integrated specification of the multiple facets of an ITS: people, their vehicles, and the external environment; and a network of sensors and actuators conveniently arranged and distributed that operates over them. The framework works with a model editor to generate specifications compliant with that language, and a code generator to produce code from them using platform specifications. There are also guidelines to help researchers in the application of this infrastructure. A case study on advanced management of traffic lights with cameras illustrates its use. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

▼ Show Figures

Graphical abstract

20 pages, 985 KiB

Open AccessArticle

Improved Measurement of Blood Pressure by Extraction of Characteristic Features from the Cuff Oscillometric Waveform

by Pooi Khoon Lim¹, Siew-Cheok Ng¹, Wissam A. Jassim¹, Stephen J. Redmond², Mohammad Zilany¹, Alberto Avolio³, Einly Lim^1,*, Maw Pin Tan⁴

and Nigel H. Lovell²

¹ Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia

² Graduate School of Biomedical Engineering, UNSW Australia, Sydney, NSW 2052, Australia

³ Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia

⁴ Department of Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia

Sensors 2015, 15(6), 14142-14161; https://doi.org/10.3390/s150614142 - 16 Jun 2015

Cited by 23 | Viewed by 10974

Abstract

We present a novel approach to improve the estimation of systolic (SBP) and diastolic blood pressure (DBP) from oscillometric waveform data using variable characteristic ratios between SBP and DBP with mean arterial pressure (MAP). This was verified in 25 healthy subjects, aged 28 [...] Read more.

We present a novel approach to improve the estimation of systolic (SBP) and diastolic blood pressure (DBP) from oscillometric waveform data using variable characteristic ratios between SBP and DBP with mean arterial pressure (MAP). This was verified in 25 healthy subjects, aged 28 ± 5 years. The multiple linear regression (MLR) and support vector regression (SVR) models were used to examine the relationship between the SBP and the DBP ratio with ten features extracted from the oscillometric waveform envelope (OWE). An automatic algorithm based on relative changes in the cuff pressure and neighbouring oscillometric pulses was proposed to remove outlier points caused by movement artifacts. Substantial reduction in the mean and standard deviation of the blood pressure estimation errors were obtained upon artifact removal. Using the sequential forward floating selection (SFFS) approach, we were able to achieve a significant reduction in the mean and standard deviation of differences between the estimated SBP values and the reference scoring (MLR: mean ± SD = −0.3 ± 5.8 mmHg; SVR and −0.6 ± 5.4 mmHg) with only two features, i.e., Ratio₂ and Area₃, as compared to the conventional maximum amplitude algorithm (MAA) method (mean ± SD = −1.6 ± 8.6 mmHg). Comparing the performance of both MLR and SVR models, our results showed that the MLR model was able to achieve comparable performance to that of the SVR model despite its simplicity. Full article

(This article belongs to the Collection Sensors for Globalized Healthy Living and Wellbeing)

▼ Show Figures

Figure 1

18 pages, 196 KiB

Open AccessArticle

Simulation of Smart Home Activity Datasets

by Jonathan Synnott^1,*

, Chris Nugent¹

and Paul Jeffers²

¹ School of Computing and Mathematics, University of Ulster, Jordanstown, County Antrim BT37 0QB, UK

² There4you, 46 Ballynanny Road, Banbridge, County Down BT32 4LQ, UK

Sensors 2015, 15(6), 14162-14179; https://doi.org/10.3390/s150614162 - 16 Jun 2015

Cited by 54 | Viewed by 9426

Abstract

A globally ageing population is resulting in an increased prevalence of chronic conditions which affect older adults. Such conditions require long-term care and management to maximize quality of life, placing an increasing strain on healthcare resources. Intelligent environments such as smart homes facilitate [...] Read more.

A globally ageing population is resulting in an increased prevalence of chronic conditions which affect older adults. Such conditions require long-term care and management to maximize quality of life, placing an increasing strain on healthcare resources. Intelligent environments such as smart homes facilitate long-term monitoring of activities in the home through the use of sensor technology. Access to sensor datasets is necessary for the development of novel activity monitoring and recognition approaches. Access to such datasets is limited due to issues such as sensor cost, availability and deployment time. The use of simulated environments and sensors may address these issues and facilitate the generation of comprehensive datasets. This paper provides a review of existing approaches for the generation of simulated smart home activity datasets, including model-based approaches and interactive approaches which implement virtual sensors, environments and avatars. The paper also provides recommendation for future work in intelligent environment simulation. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

27 pages, 4827 KiB

Open AccessArticle

From Ambient Sensing to IoT-based Context Computing: An Open Framework for End to End QoC Management

by Pierrick Marie^1,*, Thierry Desprats¹, Sophie Chabridon², Michelle Sibilla¹ and Chantal Taconet²

¹ IRIT UMR 5505 Université Paul SABATIER, 31062 Toulouse, France

² Institut Mines-Télécom, CNRS UMR 5157 SAMOVAR, Télécom SudParis, 91011 Évry, France

Sensors 2015, 15(6), 14180-14206; https://doi.org/10.3390/s150614180 - 16 Jun 2015

Cited by 12 | Viewed by 6301

Abstract

Quality of Context (QoC) awareness is recognized as a key point for the success of context-aware computing. At the time where the combination of the Internet of Things, Cloud Computing, and Ambient Intelligence paradigms offer together new opportunities for managing richer context data, [...] Read more.

Quality of Context (QoC) awareness is recognized as a key point for the success of context-aware computing. At the time where the combination of the Internet of Things, Cloud Computing, and Ambient Intelligence paradigms offer together new opportunities for managing richer context data, the next generation of Distributed Context Managers (DCM) is facing new challenges concerning QoC management. This paper presents our model-driven QoCIM framework. QoCIM is the acronym for Quality of Context Information Model. We show how it can help application developers to manage the whole QoC life-cycle by providing genericity, openness and uniformity. Its usages are illustrated, both at design time and at runtime, in the case of an urban pollution context- and QoC-aware scenario. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

▼ Show Figures

23 pages, 4875 KiB

Open AccessArticle

Fair Trade Metaphor as a Control Privacy Method for Pervasive Environments: Concepts and Evaluation

by Abraham Esquivel¹, Pablo Haya² and Xavier Alamán^3,*

¹ Instituto Tecnológico Superior Zacatecas Norte, Río Grande (Zac) 98400, Mexico

² Instituto de Ingeniería del Conocimiento, Universidad Autónoma de Madrid, Madrid 28049, Spain

³ Escuela Politécnica Superior, Universidad Autónoma de Madrid, C. Francisco Tomás y Valiente. 11, Madrid 28049, Spain

Sensors 2015, 15(6), 14207-14229; https://doi.org/10.3390/s150614207 - 16 Jun 2015

Viewed by 5296

Abstract

This paper presents a proof of concept from which the metaphor of “fair trade” is validated as an alternative to manage the private information of users. Our privacy solution deals with user’s privacy as a tradable good for obtaining environmental services. Thus, users [...] Read more.

This paper presents a proof of concept from which the metaphor of “fair trade” is validated as an alternative to manage the private information of users. Our privacy solution deals with user’s privacy as a tradable good for obtaining environmental services. Thus, users gain access to more valuable services as they share more personal information. This strategy, combined with optimistic access control and transaction registry mechanisms, enhances users’ confidence in the system while encouraging them to share their information, with the consequent benefit for the community. The study results are promising considering the user responses regarding the usefulness, ease of use, information classification and perception of control with the mechanisms proposed by the metaphor. Full article

(This article belongs to the Special Issue Select Papers from UCAmI & IWAAL 2014 – The 8th International Conference on Ubiquitous Computing and Ambient Intelligence & the 6th International Workshop on Ambient Assisted Living (UCAmI & IWAAL 2014: Pervasive Sensing Solutions))

▼ Show Figures

11 pages, 2581 KiB

Open AccessArticle

Synthesis and Gas Sensing Properties of Single La-Doped SnO₂ Nanobelts

by Yuemei Wu, Heng Zhang, Yingkai Liu^*, Weiwu Chen, Jiang Ma, Shuanghui Li and Zhaojun Qin

Institute of Physics and Electronic Information Technology, Yunnan Normal University, Kunming 650500, China

Sensors 2015, 15(6), 14230-14240; https://doi.org/10.3390/s150614230 - 16 Jun 2015

Cited by 28 | Viewed by 6727

Abstract

Single crystal SnO₂ nanobelts (SnO₂ NBs) and La-SnO₂ nanobelts (La-SnO₂ NBs) were synthesized by thermal evaporation. Both a single SnO₂ NB sensor and a single La-SnO₂ NB sensor were developed and their sensing properties were investigated. It [...] Read more.

Single crystal SnO₂ nanobelts (SnO₂ NBs) and La-SnO₂ nanobelts (La-SnO₂ NBs) were synthesized by thermal evaporation. Both a single SnO₂ NB sensor and a single La-SnO₂ NB sensor were developed and their sensing properties were investigated. It is found that the single La-SnO₂ NB sensor had a high sensitivity of 8.76 to ethanediol at a concentration of 100 ppm at 230 °C, which is the highest sensitivity of a single SnO₂ NB to ethanediol among three kinds of volatile organic (VOC) liquids studied, including ethanediol, ethanol, and acetone. The La-SnO₂ NBs sensor also exhibits a high sensitivity, good selectivity and long-term stability with prompt response time to ethanediol. The mechanism behind the enhanced sensing performance of La-doped SnO₂ nanobelts is discussed. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

Graphical abstract

20 pages, 1122 KiB

Open AccessArticle

Acoustic Biometric System Based on Preprocessing Techniques and Linear Support Vector Machines

by Lara Del Val^1,*

, Alberto Izquierdo-Fuente^2,†, Juan J. Villacorta^2,†

and Mariano Raboso^3,†

¹ Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica, Expresión Gráfica de la Ingeniería, Ingeniería Cartográfica, Geodesia y Fotogrametría, Ingeniería Mecánica e Ingeniería de los Procesos de Fabricación, Área de Ingeniería Mecánica, Universidad de Valladolid, Paseo del Cauce 59, 47011 Valladolid, Spain

² Departamento de Teoría de la Señal y Comunicaciones e Ingeniería Telemática, Universidad de Valladolid, Paseo Belén 15, 47011 Valladolid, Spain

³ Informática, Universidad Pontificia de Salamanca, Calle Compañía 5, 37002 Salamanca, Spain

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 14241-14260; https://doi.org/10.3390/s150614241 - 17 Jun 2015

Cited by 12 | Viewed by 5783

Abstract

Drawing on the results of an acoustic biometric system based on a MSE classifier, a new biometric system has been implemented. This new system preprocesses acoustic images, extracts several parameters and finally classifies them, based on Support Vector Machine (SVM). The preprocessing techniques [...] Read more.

Drawing on the results of an acoustic biometric system based on a MSE classifier, a new biometric system has been implemented. This new system preprocesses acoustic images, extracts several parameters and finally classifies them, based on Support Vector Machine (SVM). The preprocessing techniques used are spatial filtering, segmentation—based on a Gaussian Mixture Model (GMM) to separate the person from the background, masking—to reduce the dimensions of images—and binarization—to reduce the size of each image. An analysis of classification error and a study of the sensitivity of the error versus the computational burden of each implemented algorithm are presented. This allows the selection of the most relevant algorithms, according to the benefits required by the system. A significant improvement of the biometric system has been achieved by reducing the classification error, the computational burden and the storage requirements. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

25 pages, 3361 KiB

Open AccessArticle

Novel Gyroscopic Mounting for Crystal Oscillators to Increase Short and Medium Term Stability under Highly Dynamic Conditions

by Maryam Abedi^1,*, Tian Jin¹

and Kewen Sun²

¹ School of Electronics and Information Engineering, Beihang University, 37 Xueyuan Road, Haidian District, Beijing 100191, China

² School of Computer and Information, Hefei University of Technology, Tunxi Road 193, Hefei 230009, China

Sensors 2015, 15(6), 14261-14285; https://doi.org/10.3390/s150614261 - 17 Jun 2015

Cited by 1 | Viewed by 6357

Abstract

In this paper, a gyroscopic mounting method for crystal oscillators to reduce the impact of dynamic loads on their output stability has been proposed. In order to prove the efficiency of this mounting approach, each dynamic load-induced instability has been analyzed in detail. [...] Read more.

In this paper, a gyroscopic mounting method for crystal oscillators to reduce the impact of dynamic loads on their output stability has been proposed. In order to prove the efficiency of this mounting approach, each dynamic load-induced instability has been analyzed in detail. A statistical study has been performed on the elevation angle of the g-sensitivity vector of Stress Compensated-cut (SC-cut) crystals. The analysis results show that the proposed gyroscopic mounting method gives good performance for host vehicle attitude changes. A phase noise improvement of 27 dB maximum and 5.7 dB on average can be achieved in the case of steady state loads, while under sinusoidal vibration conditions, the maximum and average phase noise improvement are as high as 24 dB and 7.5 dB respectively. With this gyroscopic mounting method, random vibration-induced phase noise instability is reduced 30 dB maximum and 8.7 dB on average. Good effects are apparent for crystal g-sensitivity vectors with low elevation angle φ and azimuthal angle β. under highly dynamic conditions, indicating the probability that crystal oscillator instability will be significantly reduced by using the proposed mounting approach. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Graphical abstract

12 pages, 2760 KiB

Open AccessArticle

A Room Temperature H₂ Sensor Fabricated Using High Performance Pt-Loaded SnO₂ Nanoparticles

by Sheng-Chang Wang^* and Muhammad Omar Shaikh

Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, Tainan 710, Taiwan

Sensors 2015, 15(6), 14286-14297; https://doi.org/10.3390/s150614286 - 17 Jun 2015

Cited by 45 | Viewed by 8648

Abstract

Highly sensitive H₂ gas sensors were prepared using pure and Pt-loaded SnO₂ nanoparticles. Thick film sensors (~35 μm) were fabricated that showed a highly porous interconnected structure made of high density small grained nanoparticles. Using Pt as catalyst improved sensor response [...] Read more.

Highly sensitive H₂ gas sensors were prepared using pure and Pt-loaded SnO₂ nanoparticles. Thick film sensors (~35 μm) were fabricated that showed a highly porous interconnected structure made of high density small grained nanoparticles. Using Pt as catalyst improved sensor response and reduced the operating temperature for achieving high sensitivity because of the negative temperature coefficient observed in Pt-loaded SnO₂. The highest sensor response to 1000 ppm H₂ was 10,500 at room temperature with a response time of 20 s. The morphology of the SnO₂ nanoparticles, the surface loading concentration and dispersion of the Pt catalyst and the microstructure of the sensing layer all play a key role in the development of an effective gas sensing device. Full article

(This article belongs to the Special Issue Gas Sensors—Designs and Applications)

▼ Show Figures

Figure 1

30 pages, 4790 KiB

Open AccessArticle

An Indoor Mobile Location Estimator in Mixed Line of Sight/Non-Line of Sight Environments Using Replacement Modified Hidden Markov Models and an Interacting Multiple Model

by Jingyu Ru^*

, Chengdong Wu^*, Zixi Jia, Yufang Yang, Yunzhou Zhang and Nan Hu

School of Information, Northeastern University, Shenyang 110819, China

Sensors 2015, 15(6), 14298-14327; https://doi.org/10.3390/s150614298 - 17 Jun 2015

Cited by 6 | Viewed by 6157

Abstract

Localization as a technique to solve the complex and challenging problems besetting line-of-sight (LOS) and non-line-of-sight (NLOS) transmissions has recently attracted considerable attention in the wireless sensor network field. This paper proposes a strategy for eliminating NLOS localization errors during calculation of the [...] Read more.

Localization as a technique to solve the complex and challenging problems besetting line-of-sight (LOS) and non-line-of-sight (NLOS) transmissions has recently attracted considerable attention in the wireless sensor network field. This paper proposes a strategy for eliminating NLOS localization errors during calculation of the location of mobile terminals (MTs) in unfamiliar indoor environments. In order to improve the hidden Markov model (HMM), we propose two modified algorithms, namely, modified HMM (M-HMM) and replacement modified HMM (RM-HMM). Further, a hybrid localization algorithm that combines HMM with an interacting multiple model (IMM) is proposed to represent the velocity of mobile nodes. This velocity model is divided into a high-speed and a low-speed model, which means the nodes move at different speeds following the same mobility pattern. Each moving node continually switches its state based on its probability. Consequently, to improve precision, each moving node uses the IMM model to integrate the results from the HMM and its modified forms. Simulation experiments conducted show that our proposed algorithms perform well in both distance estimation and coordinate calculation, with increasing accuracy of localization of the proposed algorithms in the order M-HMM, RM-HMM, and HMM + IMM. The simulations also show that the three algorithms are accurate, stable, and robust. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

Figure 1

17 pages, 2708 KiB

Open AccessArticle

Fast Measurement and Reconstruction of Large Workpieces with Freeform Surfaces by Combining Local Scanning and Global Position Data

by Zhe Chen, Fumin Zhang^*, Xinghua Qu and Baoqiu Liang

State Key Lab of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China

Sensors 2015, 15(6), 14328-14344; https://doi.org/10.3390/s150614328 - 17 Jun 2015

Cited by 26 | Viewed by 6208

Abstract

In this paper, we propose a new approach for the measurement and reconstruction of large workpieces with freeform surfaces. The system consists of a handheld laser scanning sensor and a position sensor. The laser scanning sensor is used to acquire the surface and [...] Read more.

In this paper, we propose a new approach for the measurement and reconstruction of large workpieces with freeform surfaces. The system consists of a handheld laser scanning sensor and a position sensor. The laser scanning sensor is used to acquire the surface and geometry information, and the position sensor is utilized to unify the scanning sensors into a global coordinate system. The measurement process includes data collection, multi-sensor data fusion and surface reconstruction. With the multi-sensor data fusion, errors accumulated during the image alignment and registration process are minimized, and the measuring precision is significantly improved. After the dense accurate acquisition of the three-dimensional (3-D) coordinates, the surface is reconstructed using a commercial software piece, based on the Non-Uniform Rational B-Splines (NURBS) surface. The system has been evaluated, both qualitatively and quantitatively, using reference measurements provided by a commercial laser scanning sensor. The method has been applied for the reconstruction of a large gear rim and the accuracy is up to 0.0963 mm. The results prove that this new combined method is promising for measuring and reconstructing the large-scale objects with complex surface geometry. Compared with reported methods of large-scale shape measurement, it owns high freedom in motion, high precision and high measurement speed in a wide measurement range. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

11 pages, 4091 KiB

Open AccessArticle

Electrical Characterization of 3D Au Microelectrodes for Use in Retinal Prostheses

by Sangmin Lee¹, Jae Hyun Ahn¹, Jong-Mo Seo^1,2, Hum Chung² and Dong-Il Cho^1,*

¹ Department of Electrical and Computer Engineering, ISRC/ASRI, Seoul National University, Seoul 151-742, Korea

² Department of Ophthalmology, College of Medicine, Seoul National University, Seoul 110-744, Korea

Sensors 2015, 15(6), 14345-14355; https://doi.org/10.3390/s150614345 - 17 Jun 2015

Cited by 16 | Viewed by 6354

Abstract

In order to provide high-quality visual information to patients who have implanted retinal prosthetic devices, the number of microelectrodes should be large. As the number of microelectrodes is increased, the dimensions of each microelectrode must be decreased, which in turn results in an [...] Read more.

In order to provide high-quality visual information to patients who have implanted retinal prosthetic devices, the number of microelectrodes should be large. As the number of microelectrodes is increased, the dimensions of each microelectrode must be decreased, which in turn results in an increased microelectrode interface impedance and decreased injection current dynamic range. In order to improve the trade-off envelope between the number of microelectrodes and the current injection characteristics, a 3D microelectrode structure can be used as an alternative. In this paper, the electrical characteristics of 2D and 3D Au microelectrodes were investigated. In order to examine the effects of the structural difference, 2D and 3D Au microelectrodes with different base areas but similar effective surface areas were fabricated and evaluated. Interface impedances were measured and similar dynamic ranges were obtained for both 2D and 3D Au microelectrodes. These results indicate that more electrodes can be implemented in the same area if 3D designs are used. Furthermore, the 3D Au microelectrodes showed substantially enhanced electrical durability characteristics against over-injected stimulation currents, withstanding electrical currents that are much larger than the limit measured for 2D microelectrodes of similar area. This enhanced electrical durability property of 3D Au microelectrodes is a new finding in microelectrode research, and makes 3D microelectrodes very desirable devices. Full article

(This article belongs to the Section Biosensors)

▼ Show Figures

Figure 1

14 pages, 2522 KiB

Open AccessArticle

Application of Cavity Enhanced Absorption Spectroscopy to the Detection of Nitric Oxide, Carbonyl Sulphide, and Ethane—Breath Biomarkers of Serious Diseases

by Jacek Wojtas

Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Str., Warsaw 00-908, Poland

Sensors 2015, 15(6), 14356-14369; https://doi.org/10.3390/s150614356 - 17 Jun 2015

Cited by 39 | Viewed by 7974

Abstract

The paper presents one of the laser absorption spectroscopy techniques as an effective tool for sensitive analysis of trace gas species in human breath. Characterization of nitric oxide, carbonyl sulphide and ethane, and the selection of their absorption lines are described. Experiments with [...] Read more.

The paper presents one of the laser absorption spectroscopy techniques as an effective tool for sensitive analysis of trace gas species in human breath. Characterization of nitric oxide, carbonyl sulphide and ethane, and the selection of their absorption lines are described. Experiments with some biomarkers showed that detection of pathogenic changes at the molecular level is possible using this technique. Thanks to cavity enhanced spectroscopy application, detection limits at the ppb-level and short measurements time (<3 s) were achieved. Absorption lines of reference samples of the selected volatile biomarkers were probed using a distributed feedback quantum cascade laser and a tunable laser system consisting of an optical parametric oscillator and difference frequency generator. Setup using the first source provided a detection limit of 30 ppb for nitric oxide and 250 ppb for carbonyl sulphide. During experiments employing a second laser, detection limits of 0.9 ppb and 0.3 ppb were obtained for carbonyl sulphide and ethane, respectively. The conducted experiments show that this type of diagnosis would significantly increase chances for effective therapy of some diseases. Additionally, it offers non-invasive and real time measurements, high sensitivity and selectivity as well as minimizing discomfort for patients. For that reason, such sensors can be used in screening for early detection of serious diseases. Full article

(This article belongs to the Special Issue Chemical Sensors based on In Situ Spectroscopy)

▼ Show Figures

Figure 1

27 pages, 1983 KiB

Open AccessArticle

Managing Emergency Situations in the Smart City: The Smart Signal

by Ángel Asensio^*, Teresa Blanco, Rubén Blasco, Álvaro Marco

and Roberto Casas

Aragón Institute of Engineering Research (I3A), Universidad Zaragoza, Edificio IDi, Mariano Esquillor s/n, Zaragoza 50018, Spain

Sensors 2015, 15(6), 14370-14396; https://doi.org/10.3390/s150614370 - 18 Jun 2015

Cited by 25 | Viewed by 8836

Abstract

In a city there are numerous items, many of them unnoticed but essential; this is the case of the signals. Signals are considered objects with reduced technological interest, but in this paper we prove that making them smart and integrating in the IoT [...] Read more.

In a city there are numerous items, many of them unnoticed but essential; this is the case of the signals. Signals are considered objects with reduced technological interest, but in this paper we prove that making them smart and integrating in the IoT (Internet of Things) could be a relevant contribution to the Smart City. This paper presents the concept of Smart Signal, as a device conscious of its context, with communication skills, able to offer the best message to the user, and as a ubiquitous element that contributes with information to the city. We present the design considerations and a real implementation and validation of the system in one of the most challenging environments that may exist in a city: a tunnel. The main advantages of the Smart Signal are the improvement of the actual functionality of the signal providing new interaction capabilities with users and a new sensory mechanism of the Smart City. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

▼ Show Figures

Figure 1

18 pages, 20188 KiB

Open AccessArticle

Forward Looking Radar Imaging by Truncated Singular Value Decomposition and Its Application for Adverse Weather Aircraft Landing

by Yulin Huang^†, Yuebo Zha^*,†, Yue Wang and Jianyu Yang

¹ School of Electronic Engineering, University of Electronic Science and Technology of China, 2006 Xiyuan Road, Gaoxin Western District, Chengdu 611731, China

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 14397-14414; https://doi.org/10.3390/s150614397 - 18 Jun 2015

Cited by 39 | Viewed by 7141

Abstract

The forward looking radar imaging task is a practical and challenging problem for adverse weather aircraft landing industry. Deconvolution method can realize the forward looking imaging but it often leads to the noise amplification in the radar image. In this paper, a forward [...] Read more.

The forward looking radar imaging task is a practical and challenging problem for adverse weather aircraft landing industry. Deconvolution method can realize the forward looking imaging but it often leads to the noise amplification in the radar image. In this paper, a forward looking radar imaging based on deconvolution method is presented for adverse weather aircraft landing. We first present the theoretical background of forward looking radar imaging task and its application for aircraft landing. Then, we convert the forward looking radar imaging task into a corresponding deconvolution problem, which is solved in the framework of algebraic theory using truncated singular decomposition method. The key issue regarding the selecting of the truncated parameter is addressed using generalized cross validation approach. Simulation and experimental results demonstrate that the proposed method is effective in achieving angular resolution enhancement with suppressing the noise amplification in forward looking radar imaging. Full article

(This article belongs to the Section Remote Sensors)

▼ Show Figures

20 pages, 4189 KiB

Open AccessArticle

Submersible Spectrofluorometer for Real-Time Sensing of Water Quality

by Adriana Puiu^*, Luca Fiorani

, Ivano Menicucci, Marco Pistilli and Antonia Lai

Diagnostics and Metrology Laboratory, ENEA, Via Enrico Fermi 45, 00044 Frascati, Italy

Sensors 2015, 15(6), 14415-14434; https://doi.org/10.3390/s150614415 - 18 Jun 2015

Cited by 17 | Viewed by 9344

Abstract

In this work, we present a newly developed submersible spectrofluorometer (patent pending) applied to real-time sensing of water quality, suitable for monitoring some important indicators of the ecological status of natural waters such as chlorophyll-a, oil and protein-like material. For the optomechanical realization [...] Read more.

In this work, we present a newly developed submersible spectrofluorometer (patent pending) applied to real-time sensing of water quality, suitable for monitoring some important indicators of the ecological status of natural waters such as chlorophyll-a, oil and protein-like material. For the optomechanical realization of the apparatus, a novel conceptual design has been adopted in order to avoid filters and pumps while maintaining a high signal-to-noise ratio. The elimination of filters and pumps has the advantage of greater system simplicity and especially of avoiding the risk of sample degradation. The use of light-emitting diodes as an excitation source instead of Xe lamps or laser diodes helped save on size, weight, power consumption and costs. For sensor calibration we performed measurements on water samples with added chlorophyll prepared in the laboratory. The sensor functionality was tested during field campaigns conducted at Albano Lake in Latium Region of Italy as well as in the Herzliya Harbor, a few kilometers North East of Tel Aviv in Israel. The obtained results are reported in the paper. The sensitivity achieved for chlorophyll-a detection was found to be at least 0.2 µg/L. Full article

(This article belongs to the Special Issue Modern Technologies for Sensing Pollution in Air, Water, and Soil)

▼ Show Figures

Graphical abstract

23 pages, 3560 KiB

Open AccessArticle

Inertial Sensor-Based Touch and Shake Metaphor for Expressive Control of 3D Virtual Avatars

by Shashidhar Patil, Harinadha Reddy Chintalapalli, Dubeom Kim and Youngho Chai^*

Graduate School of Advanced Imaging Science, Multimedia and Film Chung-Ang University, Seoul 156-756, Korea

Sensors 2015, 15(6), 14435-14457; https://doi.org/10.3390/s150614435 - 18 Jun 2015

Cited by 7 | Viewed by 8815

Abstract

In this paper, we present an inertial sensor-based touch and shake metaphor for expressive control of a 3D virtual avatar in a virtual environment. An intuitive six degrees-of-freedom wireless inertial motion sensor is used as a gesture and motion control input device with [...] Read more.

In this paper, we present an inertial sensor-based touch and shake metaphor for expressive control of a 3D virtual avatar in a virtual environment. An intuitive six degrees-of-freedom wireless inertial motion sensor is used as a gesture and motion control input device with a sensor fusion algorithm. The algorithm enables user hand motions to be tracked in 3D space via magnetic, angular rate, and gravity sensors. A quaternion-based complementary filter is implemented to reduce noise and drift. An algorithm based on dynamic time-warping is developed for efficient recognition of dynamic hand gestures with real-time automatic hand gesture segmentation. Our approach enables the recognition of gestures and estimates gesture variations for continuous interaction. We demonstrate the gesture expressivity using an interactive flexible gesture mapping interface for authoring and controlling a 3D virtual avatar and its motion by tracking user dynamic hand gestures. This synthesizes stylistic variations in a 3D virtual avatar, producing motions that are not present in the motion database using hand gesture sequences from a single inertial motion sensor. Full article

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

▼ Show Figures

Figure 1

29 pages, 1072 KiB

Open AccessArticle

DEADS: Depth and Energy Aware Dominating Set Based Algorithm for Cooperative Routing along with Sink Mobility in Underwater WSNs

by Amara Umar¹, Nadeem Javaid^1,*

, Ashfaq Ahmad¹

, Zahoor Ali Khan²

, Umar Qasim³

, Nabil Alrajeh⁴ and Amir Hayat¹

¹ COMSATS Institute of Information Technology, Park Road, Islamabad 44000, Pakistan

² Internetworking Program, FE, Dalhousie University, Halifax, NS B3J 4R2, Canada

³ University of Alberta, AB T6G 2J8, Canada

⁴ College of Applied Medical Sciences, Department of Biomedical Technology, King Saud University, Riyadh 11633, Saudi Arabia

Sensors 2015, 15(6), 14458-14486; https://doi.org/10.3390/s150614458 - 18 Jun 2015

Cited by 54 | Viewed by 6927

Abstract

Performance enhancement of Underwater Wireless Sensor Networks (UWSNs) in terms of throughput maximization, energy conservation and Bit Error Rate (BER) minimization is a potential research area. However, limited available bandwidth, high propagation delay, highly dynamic network topology, and high error probability leads to [...] Read more.

Performance enhancement of Underwater Wireless Sensor Networks (UWSNs) in terms of throughput maximization, energy conservation and Bit Error Rate (BER) minimization is a potential research area. However, limited available bandwidth, high propagation delay, highly dynamic network topology, and high error probability leads to performance degradation in these networks. In this regard, many cooperative communication protocols have been developed that either investigate the physical layer or the Medium Access Control (MAC) layer, however, the network layer is still unexplored. More specifically, cooperative routing has not yet been jointly considered with sink mobility. Therefore, this paper aims to enhance the network reliability and efficiency via dominating set based cooperative routing and sink mobility. The proposed work is validated via simulations which show relatively improved performance of our proposed work in terms the selected performance metrics. Full article

(This article belongs to the Section Sensor Networks)

▼ Show Figures

26 pages, 972 KiB

Open AccessArticle

Hands-On Experiences in Deploying Cost-Effective Ambient-Assisted Living Systems

by Athanasios Dasios^1,*, Damianos Gavalas^1,2, Grammati Pantziou³ and Charalampos Konstantopoulos⁴

¹ School of Science and Technology, Hellenic Open University, Patras GR-26335, Greece

² Department of Cultural Technology and Communication, University of the Aegean, Mytilene GR-81100, Greece

³ Department of Informatics, Technological Educational Institution of Athens, Athens GR-12243, Greece

⁴ Department of Informatics, University of Piraeus, Piraeus GR-18534, Greece

Sensors 2015, 15(6), 14487-14512; https://doi.org/10.3390/s150614487 - 18 Jun 2015

Cited by 50 | Viewed by 12301

Abstract

Older adults’ preferences to remain independent in their own homes along with the high costs of nursing home care have motivated the development of Ambient Assisted Living (AAL) technologies which aim at improving the safety, health conditions and wellness of the elderly. This [...] Read more.

Older adults’ preferences to remain independent in their own homes along with the high costs of nursing home care have motivated the development of Ambient Assisted Living (AAL) technologies which aim at improving the safety, health conditions and wellness of the elderly. This paper reports hands-on experiences in designing, implementing and operating UbiCare, an AAL based prototype system for elderly home care monitoring. The monitoring is based on the recording of environmental parameters like temperature and light intensity as well as micro-level incidents which allows one to infer daily activities like moving, sitting, sleeping, usage of electrical appliances and plumbing components. The prototype is built upon inexpensive, off-the-shelf hardware (e.g., various sensors, Arduino microcontrollers, ZigBee-compatible wireless communication modules) and license-free software, thereby ensuring low system deployment costs. The network comprises nodes placed in a house’s main rooms or mounted on furniture, one wearable node, one actuator node and a centralized processing element (coordinator). Upon detecting significant deviations from the ordinary activity patterns of individuals and/or sudden falls, the system issues automated alarms which may be forwarded to authorized caregivers via a variety of communication channels. Furthermore, measured environmental parameters and activity incidents may be monitored through standard web interfaces. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

▼ Show Figures

Graphical abstract

13 pages, 801 KiB

Open AccessReview

The Role of Infrared Thermography as a Non-Invasive Tool for the Detection of Lameness in Cattle

by Maher Alsaaod^1,*, Allan L. Schaefer², Wolfgang Büscher³

and Adrian Steiner¹

¹ Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bern 3001, Switzerland

² Agriculture Forestry Centre, Department of AFNS, University of Alberta, Edmonton, AB T6G 2P5, Canada

³ Livestock Technology Section, Institute for Agricultural Engineering, University of Bonn, Nussallee 5, Bonn D-53115, Germany

Sensors 2015, 15(6), 14513-14525; https://doi.org/10.3390/s150614513 - 18 Jun 2015

Cited by 65 | Viewed by 10103

Abstract

The use of infrared thermography for the identification of lameness in cattle has increased in recent years largely because of its non-invasive properties, ease of automation and continued cost reductions. Thermography can be used to identify and determine thermal abnormalities in animals by [...] Read more.

The use of infrared thermography for the identification of lameness in cattle has increased in recent years largely because of its non-invasive properties, ease of automation and continued cost reductions. Thermography can be used to identify and determine thermal abnormalities in animals by characterizing an increase or decrease in the surface temperature of their skin. The variation in superficial thermal patterns resulting from changes in blood flow in particular can be used to detect inflammation or injury associated with conditions such as foot lesions. Thermography has been used not only as a diagnostic tool, but also to evaluate routine farm management. Since 2000, 14 peer reviewed papers which discuss the assessment of thermography to identify and manage lameness in cattle have been published. There was a large difference in thermography performance in these reported studies. However, thermography was demonstrated to have utility for the detection of contralateral temperature difference and maximum foot temperature on areas of interest. Also apparent in these publications was that a controlled environment is an important issue that should be considered before image scanning. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

13 pages, 860 KiB

Open AccessArticle

Simultaneous Voltammetric/Amperometric Determination of Sulfide and Nitrite in Water at BDD Electrode

by Anamaria Baciu, Magdalena Ardelean, Aniela Pop, Rodica Pode and Florica Manea^*

Department of Applied Chemistry and Engineering of Inorganic Compounds and Environment, Politehnica University of Timisoara, V. Parvan no. 6, Timișoara 300223, Romania

Sensors 2015, 15(6), 14526-14538; https://doi.org/10.3390/s150614526 - 19 Jun 2015

Cited by 35 | Viewed by 7862

Abstract

This work reported new voltammetric/amperometric-based protocols using a commercial boron-doped diamond (BDD) electrode for simple and fast simultaneous detection of sulfide and nitrite from water. Square-wave voltammetry operated under the optimized working conditions of 0.01 V step potential, 0.5 V modulation amplitude and [...] Read more.

This work reported new voltammetric/amperometric-based protocols using a commercial boron-doped diamond (BDD) electrode for simple and fast simultaneous detection of sulfide and nitrite from water. Square-wave voltammetry operated under the optimized working conditions of 0.01 V step potential, 0.5 V modulation amplitude and 10 Hz frequency allowed achieving the best electroanalytical parameters for the simultaneous detection of nitrite and sulfide. For practical in-field detection applications, the multiple-pulsed amperometry technique was operated under optimized conditions, i.e., −0.5 V/SCE for a duration of 0.3 s as conditioning step, +0.85 V/SCE for a duration of 3 s that assure the sulfide oxidation and +1.25 V/SCE for a duration of 0.3 s, where the nitrite oxidation occurred, which allowed the simultaneously detection of sulfide and nitrite without interference between them. Good accuracy was found for this protocol in comparison with standardized methods for each anion. Also, no interference effect was found for the cation and anion species, which are common in the water matrix. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

Figure 1

30 pages, 1484 KiB

Open AccessReview

DNA-Based Nanobiosensors as an Emerging Platform for Detection of Disease

by Khalid M. Abu-Salah^1,2,3,*, Mohammed M. Zourob⁴, Fouzi Mouffouk⁵, Salman A. Alrokayan^1,2, Manal A. Alaamery³ and Anees A. Ansari²

¹ Research Chair for Medical Applications of Nanomaterials, King Saud University, PO Box 2454, Riyadh 11451, Saudi Arabia

² King Abdullah Institute for Nanotechnology, King Saud University, PO Box 2454, Riyadh 11451, Saudi Arabia

³ King Abdulla International Medical Research Center, King Abdulaziz Medical City, PO Box 22490, Riyadh 11426, Saudi Arabia

⁴ Department of Chemistry, Alfaisal University, Al Zahrawi Street, Al Maather, Al Takhassusi Rd, Riyadh 11533, Saudi Arabia

⁵ Chemistry Department, Faculty of Science, Kuwait University, PO Box 2969, Kuwait

Sensors 2015, 15(6), 14539-14568; https://doi.org/10.3390/s150614539 - 19 Jun 2015

Cited by 131 | Viewed by 18497

Abstract

Detection of disease at an early stage is one of the biggest challenges in medicine. Different disciplines of science are working together in this regard. The goal of nanodiagnostics is to provide more accurate tools for earlier diagnosis, to reduce cost and to [...] Read more.

Detection of disease at an early stage is one of the biggest challenges in medicine. Different disciplines of science are working together in this regard. The goal of nanodiagnostics is to provide more accurate tools for earlier diagnosis, to reduce cost and to simplify healthcare delivery of effective and personalized medicine, especially with regard to chronic diseases (e.g., diabetes and cardiovascular diseases) that have high healthcare costs. Up-to-date results suggest that DNA-based nanobiosensors could be used effectively to provide simple, fast, cost-effective, sensitive and specific detection of some genetic, cancer, and infectious diseases. In addition, they could potentially be used as a platform to detect immunodeficiency, and neurological and other diseases. This review examines different types of DNA-based nanobiosensors, the basic principles upon which they are based and their advantages and potential in diagnosis of acute and chronic diseases. We discuss recent trends and applications of new strategies for DNA-based nanobiosensors, and emphasize the challenges in translating basic research to the clinical laboratory. Full article

(This article belongs to the Section Biosensors)

▼ Show Figures

Figure 1

22 pages, 648 KiB

Open AccessArticle

On-Board Event-Based State Estimation for Trajectory Approaching and Tracking of a Vehicle

by Miguel Martínez-Rey^*, Felipe Espinosa

, Alfredo Gardel

and Carlos Santos

Department of Electronics, University of Alcalá. Polytechnic School, Campus Universitario, Alcalá de Henares 28871, Spain

Sensors 2015, 15(6), 14569-14590; https://doi.org/10.3390/s150614569 - 19 Jun 2015

Cited by 18 | Viewed by 7081

Abstract

For the problem of pose estimation of an autonomous vehicle using networked external sensors, the processing capacity and battery consumption of these sensors, as well as the communication channel load should be optimized. Here, we report an event-based state estimator (EBSE) consisting of [...] Read more.

For the problem of pose estimation of an autonomous vehicle using networked external sensors, the processing capacity and battery consumption of these sensors, as well as the communication channel load should be optimized. Here, we report an event-based state estimator (EBSE) consisting of an unscented Kalman filter that uses a triggering mechanism based on the estimation error covariance matrix to request measurements from the external sensors. This EBSE generates the events of the estimator module on-board the vehicle and, thus, allows the sensors to remain in stand-by mode until an event is generated. The proposed algorithm requests a measurement every time the estimation distance root mean squared error (DRMS) value, obtained from the estimator’s covariance matrix, exceeds a threshold value. This triggering threshold can be adapted to the vehicle’s working conditions rendering the estimator even more efficient. An example of the use of the proposed EBSE is given, where the autonomous vehicle must approach and follow a reference trajectory. By making the threshold a function of the distance to the reference location, the estimator can halve the use of the sensors with a negligible deterioration in the performance of the approaching maneuver. Full article

(This article belongs to the Special Issue Cyber-Physical Systems)

▼ Show Figures

24 pages, 6919 KiB

Open AccessArticle

Citizen Sensors for SHM: Towards a Crowdsourcing Platform

by Ekin Ozer^*

, Maria Q. Feng and Dongming Feng

Department of Civil Engineering and Engineering Mechanics, Columbia University, 500 W 120th St, New York, NY 10027, USA

Sensors 2015, 15(6), 14591-14614; https://doi.org/10.3390/s150614591 - 19 Jun 2015

Cited by 85 | Viewed by 9476

Abstract

This paper presents an innovative structural health monitoring (SHM) platform in terms of how it integrates smartphone sensors, the web, and crowdsourcing. The ubiquity of smartphones has provided an opportunity to create low-cost sensor networks for SHM. Crowdsourcing has given rise to citizen [...] Read more.

This paper presents an innovative structural health monitoring (SHM) platform in terms of how it integrates smartphone sensors, the web, and crowdsourcing. The ubiquity of smartphones has provided an opportunity to create low-cost sensor networks for SHM. Crowdsourcing has given rise to citizen initiatives becoming a vast source of inexpensive, valuable but heterogeneous data. Previously, the authors have investigated the reliability of smartphone accelerometers for vibration-based SHM. This paper takes a step further to integrate mobile sensing and web-based computing for a prospective crowdsourcing-based SHM platform. An iOS application was developed to enable citizens to measure structural vibration and upload the data to a server with smartphones. A web-based platform was developed to collect and process the data automatically and store the processed data, such as modal properties of the structure, for long-term SHM purposes. Finally, the integrated mobile and web-based platforms were tested to collect the low-amplitude ambient vibration data of a bridge structure. Possible sources of uncertainties related to citizens were investigated, including the phone location, coupling conditions, and sampling duration. The field test results showed that the vibration data acquired by smartphones operated by citizens without expertise are useful for identifying structural modal properties with high accuracy. This platform can be further developed into an automated, smart, sustainable, cost-free system for long-term monitoring of structural integrity of spatially distributed urban infrastructure. Citizen Sensors for SHM will be a novel participatory sensing platform in the way that it offers hybrid solutions to transitional crowdsourcing parameters. Full article

(This article belongs to the Special Issue Sensors and Smart Cities)

▼ Show Figures

Figure 1

24 pages, 2458 KiB

Open AccessArticle

Fingerprint Liveness Detection in the Presence of Capable Intruders

by Ana F. Sequeira^1,2,* and Jaime S. Cardoso^1,2

¹ INESC TEC—INESC Technology and Science, Campus da FEUP, Rua Dr. Roberto Frias, Porto 4200-465, Portugal

² Departamento de Engenharia Eletrotécnica e de Computadores, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, Porto 4200-465, Portugal

Sensors 2015, 15(6), 14615-14638; https://doi.org/10.3390/s150614615 - 19 Jun 2015

Cited by 27 | Viewed by 7291

Abstract

Fingerprint liveness detection methods have been developed as an attempt to overcome the vulnerability of fingerprint biometric systems to spoofing attacks. Traditional approaches have been quite optimistic about the behavior of the intruder assuming the use of a previously known material. This assumption [...] Read more.

Fingerprint liveness detection methods have been developed as an attempt to overcome the vulnerability of fingerprint biometric systems to spoofing attacks. Traditional approaches have been quite optimistic about the behavior of the intruder assuming the use of a previously known material. This assumption has led to the use of supervised techniques to estimate the performance of the methods, using both live and spoof samples to train the predictive models and evaluate each type of fake samples individually. Additionally, the background was often included in the sample representation, completely distorting the decision process. Therefore, we propose that an automatic segmentation step should be performed to isolate the fingerprint from the background and truly decide on the liveness of the fingerprint and not on the characteristics of the background. Also, we argue that one cannot aim to model the fake samples completely since the material used by the intruder is unknown beforehand. We approach the design by modeling the distribution of the live samples and predicting as fake the samples very unlikely according to that model. Our experiments compare the performance of the supervised approaches with the semi-supervised ones that rely solely on the live samples. The results obtained differ from the ones obtained by the more standard approaches which reinforces our conviction that the results in the literature are misleadingly estimating the true vulnerability of the biometric system. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

22 pages, 19277 KiB

Open AccessArticle

Loop Closing Detection in RGB-D SLAM Combining Appearance and Geometric Constraints

by Heng Zhang^1,2

, Yanli Liu^1,2,* and Jindong Tan²

¹ School of Information Engineering, East China Jiaotong University, Nanchang 330013, China

² Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996, USA

Sensors 2015, 15(6), 14639-14660; https://doi.org/10.3390/s150614639 - 19 Jun 2015

Cited by 18 | Viewed by 8792

Abstract

A kind of multi feature points matching algorithm fusing local geometric constraints is proposed for the purpose of quickly loop closing detection in RGB-D Simultaneous Localization and Mapping (SLAM). The visual feature is encoded with BRAND (binary robust appearance and normals descriptor), which [...] Read more.

A kind of multi feature points matching algorithm fusing local geometric constraints is proposed for the purpose of quickly loop closing detection in RGB-D Simultaneous Localization and Mapping (SLAM). The visual feature is encoded with BRAND (binary robust appearance and normals descriptor), which efficiently combines appearance and geometric shape information from RGB-D images. Furthermore, the feature descriptors are stored using the Locality-Sensitive-Hashing (LSH) technique and hierarchical clustering trees are used to search for these binary features. Finally, the algorithm for matching of multi feature points using local geometric constraints is provided, which can effectively reject the possible false closure hypotheses. We demonstrate the efficiency of our algorithms by real-time RGB-D SLAM with loop closing detection in indoor image sequences taken with a handheld Kinect camera and comparative experiments using other algorithms in RTAB-Map dealing with a benchmark dataset. Full article

(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)

▼ Show Figures

18 pages, 9536 KiB

Open AccessArticle

Radar Sensing for Intelligent Vehicles in Urban Environments

by Giulio Reina^1,*, David Johnson² and James Underwood²

¹ Department of Engineering for Innovation, University of Salento, via Arnesano, 73100 Lecce, Italy

² Australian Centre for Field Robotics, University of Sydney, Rose Street Building (J04), 2006 Sydney, Australia

Sensors 2015, 15(6), 14661-14678; https://doi.org/10.3390/s150614661 - 19 Jun 2015

Cited by 76 | Viewed by 10913

Abstract

Radar overcomes the shortcomings of laser, stereovision, and sonar because it can operate successfully in dusty, foggy, blizzard-blinding, and poorly lit scenarios. This paper presents a novel method for ground and obstacle segmentation based on radar sensing. The algorithm operates directly in the [...] Read more.

Radar overcomes the shortcomings of laser, stereovision, and sonar because it can operate successfully in dusty, foggy, blizzard-blinding, and poorly lit scenarios. This paper presents a novel method for ground and obstacle segmentation based on radar sensing. The algorithm operates directly in the sensor frame, without the need for a separate synchronised navigation source, calibration parameters describing the location of the radar in the vehicle frame, or the geometric restrictions made in the previous main method in the field. Experimental results are presented in various urban scenarios to validate this approach, showing its potential applicability for advanced driving assistance systems and autonomous vehicle operations. Full article

(This article belongs to the Special Issue Sensors in New Road Vehicles)

▼ Show Figures

22 pages, 4195 KiB

Open AccessArticle

Gaze-Assisted User Intention Prediction for Initial Delay Reduction in Web Video Access

by Seungyup Lee^1,2, Juwan Yoo^1,2 and Gunhee Han^1,2,*

¹ School of Integrated Technology, Yonsei University, Incheon 406-840, Korea

² Yonsei Institute of Convergence Technology, Yonsei University, Incheon 406-840, Korea

Sensors 2015, 15(6), 14679-14700; https://doi.org/10.3390/s150614679 - 19 Jun 2015

Cited by 13 | Viewed by 7363

Abstract

Despite the remarkable improvement of hardware and network technology, the inevitable delay from a user’s command action to a system response is still one of the most crucial influence factors in user experiences (UXs). Especially for a web video service, an initial delay [...] Read more.

Despite the remarkable improvement of hardware and network technology, the inevitable delay from a user’s command action to a system response is still one of the most crucial influence factors in user experiences (UXs). Especially for a web video service, an initial delay from click action to video start has significant influences on the quality of experience (QoE). The initial delay of a system can be minimized by preparing execution based on predicted user’s intention prior to actual command action. The introduction of the sequential and concurrent flow of resources in human cognition and behavior can significantly improve the accuracy and preparation time for intention prediction. This paper introduces a threaded interaction model and applies it to user intention prediction for initial delay reduction in web video access. The proposed technique consists of a candidate selection module, a decision module and a preparation module that prefetches and preloads the web video data before a user’s click action. The candidate selection module selects candidates in the web page using proximity calculation around a cursor. Meanwhile, the decision module computes the possibility of actual click action based on the cursor-gaze relationship. The preparation activates the prefetching for the selected candidates when the click possibility exceeds a certain limit in the decision module. Experimental results show a 92% hit-ratio, 0.5-s initial delay on average and 1.5-s worst initial delay, which is much less than a user’s tolerable limit in web video access, demonstrating significant improvement of accuracy and advance time in intention prediction by introducing the proposed threaded interaction model. Full article

(This article belongs to the Special Issue HCI In Smart Environments)

▼ Show Figures

26 pages, 4549 KiB

Open AccessArticle

Performance Analysis of Several GPS/Galileo Precise Point Positioning Models

by Akram Afifi^* and Ahmed El-Rabbany

Department of Civil Engineering, Ryerson University, Toronto, ON M5B 2K3, Canada

Sensors 2015, 15(6), 14701-14726; https://doi.org/10.3390/s150614701 - 19 Jun 2015

Cited by 18 | Viewed by 6346

Abstract

This paper examines the performance of several precise point positioning (PPP) models, which combine dual-frequency GPS/Galileo observations in the un-differenced and between-satellite single-difference (BSSD) modes. These include the traditional un-differenced model, the decoupled clock model, the semi-decoupled clock model, and the between-satellite single-difference [...] Read more.

This paper examines the performance of several precise point positioning (PPP) models, which combine dual-frequency GPS/Galileo observations in the un-differenced and between-satellite single-difference (BSSD) modes. These include the traditional un-differenced model, the decoupled clock model, the semi-decoupled clock model, and the between-satellite single-difference model. We take advantage of the IGS-MGEX network products to correct for the satellite differential code biases and the orbital and satellite clock errors. Natural Resources Canada’s GPSPace PPP software is modified to handle the various GPS/Galileo PPP models. A total of six data sets of GPS and Galileo observations at six IGS stations are processed to examine the performance of the various PPP models. It is shown that the traditional un-differenced GPS/Galileo PPP model, the GPS decoupled clock model, and the semi-decoupled clock GPS/Galileo PPP model improve the convergence time by about 25% in comparison with the un-differenced GPS-only model. In addition, the semi-decoupled GPS/Galileo PPP model improves the solution precision by about 25% compared to the traditional un-differenced GPS/Galileo PPP model. Moreover, the BSSD GPS/Galileo PPP model improves the solution convergence time by about 50%, in comparison with the un-differenced GPS PPP model, regardless of the type of BSSD combination used. As well, the BSSD model improves the precision of the estimated parameters by about 50% and 25% when the loose and the tight combinations are used, respectively, in comparison with the un-differenced GPS-only model. Comparable results are obtained through the tight combination when either a GPS or a Galileo satellite is selected as a reference. Full article

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

▼ Show Figures

Figure 1

18 pages, 3486 KiB

Open AccessArticle

A 3-Axis Miniature Magnetic Sensor Based on a Planar Fluxgate Magnetometer with an Orthogonal Fluxguide

by Chih-Cheng Lu^1,2,* and Jeff Huang¹

¹ Institute of Mechatronic Engineering, National Taipei University of Technology, Taipei 106, Taiwan

² Department of Mechanical Engineering, National Taipei University of Technology, Taipei 106, Taiwan

Sensors 2015, 15(6), 14727-14744; https://doi.org/10.3390/s150614727 - 19 Jun 2015

Cited by 42 | Viewed by 15937

Abstract

A new class of tri-axial miniature magnetometer consisting of a planar fluxgate structure with an orthogonal ferromagnetic fluxguide centrally situated over the magnetic cores is presented. The magnetic sensor possesses a cruciform ferromagnetic core placed diagonally upon the square excitation coil under which [...] Read more.

A new class of tri-axial miniature magnetometer consisting of a planar fluxgate structure with an orthogonal ferromagnetic fluxguide centrally situated over the magnetic cores is presented. The magnetic sensor possesses a cruciform ferromagnetic core placed diagonally upon the square excitation coil under which two pairs of pick-up coils for in-plane field detection are allocated. Effective principles and analysis of the magnetometer for 3-D field vectors are described and verified by numerically electromagnetic simulation for the excitation and magnetization of the ferromagnetic cores. The sensor is operated by applying the second-harmonic detection technique that can verify V-B relationship and device responsivity. Experimental characterization of the miniature fluxgate device demonstrates satisfactory spatial magnetic field detection results in terms of responsivity and noise spectrum. As a result, at an excitation frequency of 50 kHz, a maximum in-plane responsivity of 122.4 V/T appears and a maximum out-of-plane responsivity of 11.6 V/T is obtained as well. The minimum field noise spectra are found to be 0.11 nT/√Hz and 6.29 nT/√Hz, respectively, in X- and Z-axis at 1 Hz under the same excitation frequency. Compared with the previous tri-axis fluxgate devices, this planar magnetic sensor with an orthogonal fluxguide provides beneficial enhancement in both sensory functionality and manufacturing simplicity. More importantly, this novel device concept is considered highly suitable for the extension to a silicon sensor made by the current CMOS-MEMS technologies, thus emphasizing its emerging applications of field detection in portable industrial electronics. Full article

(This article belongs to the Special Issue Magnetic Sensor Device-Part 1)

▼ Show Figures

Figure 1

12 pages, 3413 KiB

Open AccessArticle

Electrothermally-Actuated Micromirrors with Bimorph Actuators—Bending-Type and Torsion-Type

by Cheng-Hua Tsai^†, Chun-Wei Tsai^†, Hsu-Tang Chang, Shih-Hsiang Liu and Jui-Che Tsai^*

¹ Graduate Institute of Photonics and Optoelectronics and the Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan

^† These authors contributed equally to this work.

Sensors 2015, 15(6), 14745-14756; https://doi.org/10.3390/s150614745 - 22 Jun 2015

Cited by 17 | Viewed by 6916

Abstract

Three different electrothermally-actuated MEMS micromirrors with Cr/Au-Si bimorph actuators are proposed. The devices are fabricated with the SOIMUMPs process developed by MEMSCAP, Inc. (Durham, NC, USA). A silicon-on-insulator MEMS process has been employed for the fabrication of these micromirrors. Electrothermal actuation has achieved [...] Read more.

Three different electrothermally-actuated MEMS micromirrors with Cr/Au-Si bimorph actuators are proposed. The devices are fabricated with the SOIMUMPs process developed by MEMSCAP, Inc. (Durham, NC, USA). A silicon-on-insulator MEMS process has been employed for the fabrication of these micromirrors. Electrothermal actuation has achieved a large angular movement in the micromirrors. Application of an external electric current 0.04 A to the bending-type, restricted-torsion-type, and free-torsion-type mirrors achieved rotation angles of 1.69°, 3.28°, and 3.64°, respectively. Full article

(This article belongs to the Section Physical Sensors)

▼ Show Figures

Figure 1

9 pages, 882 KiB

Open AccessArticle

First-Principles Studies of Hydrogen Adsorption at Pd-SiO₂ Interfaces

by Yoshihiro Irokawa^1,* and Mamoru Usami²

¹ National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan

² ASMS Co., Ltd., 1-10-7 Higashi-Gotanda, Shinagawa, Tokyo 141-0022, Japan

Sensors 2015, 15(6), 14757-14765; https://doi.org/10.3390/s150614757 - 22 Jun 2015

Cited by 9 | Viewed by 6643

Abstract

The interaction of hydrogen with Pd-SiO₂ interfaces has been investigated for the first time using first-principles calculations based on density functional theory. The hydrogen-induced polarization at the Pd-SiO₂ interfaces was evaluated using Pd-SiO₂ interface supercells. As a result, the potential [...] Read more.

The interaction of hydrogen with Pd-SiO₂ interfaces has been investigated for the first time using first-principles calculations based on density functional theory. The hydrogen-induced polarization at the Pd-SiO₂ interfaces was evaluated using Pd-SiO₂ interface supercells. As a result, the potential change induced by interfacial hydrogen atoms was not observed even for hydrogen concentration of ~1.3 × 10¹⁵ cm⁻² at the Pd-SiO₂ interface. This result implies that hydrogen does not create an electric double layer at the Pd-SiO₂ interface but change the property of the SiO₂ region, resulting in the hydrogen sensitivity of the devices. Full article

(This article belongs to the Section Chemical Sensors)

▼ Show Figures

Figure 1

22 pages, 2728 KiB

Open AccessReview

Biosensing with Förster Resonance Energy Transfer Coupling between Fluorophores and Nanocarbon Allotropes

by Shaowei Ding¹, Allison A. Cargill¹, Suprem R. Das¹, Igor L. Medintz² and Jonathan C. Claussen^1,*

¹ Department of Mechanical Engineering, Iowa State University, 2104 Black Engineering, Ames, IA 50011, USA

² Center for Bio/Molecular Science & Engineering Code 6900, US Naval Research Laboratory, Washington, DC 20375, USA

Sensors 2015, 15(6), 14766-14787; https://doi.org/10.3390/s150614766 - 23 Jun 2015

Cited by 33 | Viewed by 10004

Abstract

Nanocarbon allotropes (NCAs), including zero-dimensional carbon dots (CDs), one-dimensional carbon nanotubes (CNTs) and two-dimensional graphene, exhibit exceptional material properties, such as unique electrical/thermal conductivity, biocompatibility and high quenching efficiency, that make them well suited for both electrical/electrochemical and optical sensors/biosensors alike. In particular, [...] Read more.

Nanocarbon allotropes (NCAs), including zero-dimensional carbon dots (CDs), one-dimensional carbon nanotubes (CNTs) and two-dimensional graphene, exhibit exceptional material properties, such as unique electrical/thermal conductivity, biocompatibility and high quenching efficiency, that make them well suited for both electrical/electrochemical and optical sensors/biosensors alike. In particular, these material properties have been exploited to significantly enhance the transduction of biorecognition events in fluorescence-based biosensing involving Förster resonant energy transfer (FRET). This review analyzes current advances in sensors and biosensors that utilize graphene, CNTs or CDs as the platform in optical sensors and biosensors. Widely utilized synthesis/fabrication techniques, intrinsic material properties and current research examples of such nanocarbon, FRET-based sensors/biosensors are illustrated. The future outlook and challenges for the research field are also detailed. Full article

(This article belongs to the Special Issue FRET Biosensors)

▼ Show Figures

Graphical abstract

21 pages, 1232 KiB

Open AccessArticle

Design of a Thermoacoustic Sensor for Low Intensity Ultrasound Measurements Based on an Artificial Neural Network

by Jida Xing¹ and Jie Chen^1,2,*

¹ Faculty of Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada

² Canadian National Research Council National Institute for Nanotechnology, Edmonton, AB T6G 2M9, Canada

Sensors 2015, 15(6), 14788-14808; https://doi.org/10.3390/s150614788 - 23 Jun 2015

Cited by 8 | Viewed by 7489

Abstract

In therapeutic ultrasound applications, accurate ultrasound output intensities are crucial because the physiological effects of therapeutic ultrasound are very sensitive to the intensity and duration of these applications. Although radiation force balance is a benchmark technique for measuring ultrasound intensity and power, it [...] Read more.

In therapeutic ultrasound applications, accurate ultrasound output intensities are crucial because the physiological effects of therapeutic ultrasound are very sensitive to the intensity and duration of these applications. Although radiation force balance is a benchmark technique for measuring ultrasound intensity and power, it is costly, difficult to operate, and compromised by noise vibration. To overcome these limitations, the development of a low-cost, easy to operate, and vibration-resistant alternative device is necessary for rapid ultrasound intensity measurement. Therefore, we proposed and validated a novel two-layer thermoacoustic sensor using an artificial neural network technique to accurately measure low ultrasound intensities between 30 and 120 mW/cm². The first layer of the sensor design is a cylindrical absorber made of plexiglass, followed by a second layer composed of polyurethane rubber with a high attenuation coefficient to absorb extra ultrasound energy. The sensor determined ultrasound intensities according to a temperature elevation induced by heat converted from incident acoustic energy. Compared with our previous one-layer sensor design, the new two-layer sensor enhanced the ultrasound absorption efficiency to provide more rapid and reliable measurements. Using a three-dimensional model in the K-wave toolbox, our simulation of the ultrasound propagation process demonstrated that the two-layer design is more efficient than the single layer design. We also integrated an artificial neural network algorithm to compensate for the large measurement offset. After obtaining multiple parameters of the sensor characteristics through calibration, the artificial neural network is built to correct temperature drifts and increase the reliability of our thermoacoustic measurements through iterative training about ten seconds. The performance of the artificial neural network method was validated through a series of experiments. Compared to our previous design, the new design reduced sensing time from 20 s to 12 s, and the sensor’s average error from 3.97 mW/cm² to 1.31 mW/cm² respectively. Full article

(This article belongs to the Special Issue Acoustic Waveguide Sensors)

▼ Show Figures

Figure 1

Journal Menu

Journal Browser

Sensors, Volume 15, Issue 6 (June 2015) – 135 articles , Pages 12103-14829

Further Information

Guidelines

MDPI Initiatives

Follow MDPI