Sensors

19 pages, 1716 KiB

Open AccessArticle

Instantaneous Real-Time Kinematic Decimeter-Level Positioning with BeiDou Triple-Frequency Signals over Medium Baselines

by Xiyang He^1,2, Xiaohong Zhang^1,2,*, Long Tang^1,2,*

and Wanke Liu^1,2

¹ School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

² Collaborative Innovation Center for Geospatial Technology, 129 Luoyu Road, Wuhan 430079, China

Sensors 2016, 16(1), 1; https://doi.org/10.3390/s16010001 - 22 Dec 2015

Cited by 47 | Viewed by 5639

Abstract

Many applications, such as marine navigation, land vehicles location, etc., require real time precise positioning under medium or long baseline conditions. In this contribution, we develop a model of real-time kinematic decimeter-level positioning with BeiDou Navigation Satellite System (BDS) triple-frequency signals over [...] Read more.

Many applications, such as marine navigation, land vehicles location, etc., require real time precise positioning under medium or long baseline conditions. In this contribution, we develop a model of real-time kinematic decimeter-level positioning with BeiDou Navigation Satellite System (BDS) triple-frequency signals over medium distances. The ambiguities of two extra-wide-lane (EWL) combinations are fixed first, and then a wide lane (WL) combination is reformed based on the two EWL combinations for positioning. Theoretical analysis and empirical analysis is given of the ambiguity fixing rate and the positioning accuracy of the presented method. The results indicate that the ambiguity fixing rate can be up to more than 98% when using BDS medium baseline observations, which is much higher than that of dual-frequency Hatch-Melbourne-Wübbena (HMW) method. As for positioning accuracy, decimeter level accuracy can be achieved with this method, which is comparable to that of carrier-smoothed code differential positioning method. Signal interruption simulation experiment indicates that the proposed method can realize fast high-precision positioning whereas the carrier-smoothed code differential positioning method needs several hundreds of seconds for obtaining high precision results. We can conclude that a relatively high accuracy and high fixing rate can be achieved for triple-frequency WL method with single-epoch observations, displaying significant advantage comparing to traditional carrier-smoothed code differential positioning method. Full article

(This article belongs to the Section Remote Sensors)

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20 pages, 4068 KiB

Open AccessArticle

Damage Detection in Flexible Plates through Reduced-Order Modeling and Hybrid Particle-Kalman Filtering

by Giovanni Capellari¹, Saeed Eftekhar Azam^2,* and Stefano Mariani¹

¹ Politecnico di Milano, Dipartimento di Ingegneria Civile e Ambientale, Piazza L. da Vinci 32, 20133 Milano, Italy

² University of Thessaly, Department of Mechanical Engineering, Leoforos Athinon, Pedion Areos, 38334 Volos, Greece

Sensors 2016, 16(1), 2; https://doi.org/10.3390/s16010002 - 22 Dec 2015

Cited by 26 | Viewed by 4975

Abstract

Health monitoring of lightweight structures, like thin flexible plates, is of interest in several engineering fields. In this paper, a recursive Bayesian procedure is proposed to monitor the health of such structures through data collected by a network of optimally placed inertial sensors. [...] Read more.

Health monitoring of lightweight structures, like thin flexible plates, is of interest in several engineering fields. In this paper, a recursive Bayesian procedure is proposed to monitor the health of such structures through data collected by a network of optimally placed inertial sensors. As a main drawback of standard monitoring procedures is linked to the computational costs, two remedies are jointly considered: first, an order-reduction of the numerical model used to track the structural dynamics, enforced with proper orthogonal decomposition; and, second, an improved particle filter, which features an extended Kalman updating of each evolving particle before the resampling stage. The former remedy can reduce the number of effective degrees-of-freedom of the structural model to a few only (depending on the excitation), whereas the latter one allows to track the evolution of damage and to locate it thanks to an intricate formulation. To assess the effectiveness of the proposed procedure, the case of a plate subject to bending is investigated; it is shown that, when the procedure is appropriately fed by measurements, damage is efficiently and accurately estimated. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 2133 KiB

Open AccessArticle

Fault-Tolerant Algorithms for Connectivity Restoration in Wireless Sensor Networks

by Yali Zeng^*, Li Xu^* and Zhide Chen

Fujian Provincial Key Laboratory of Network Security and Cryptology, School of Mathematics and Computer Science, Fujian Normal University, Fuzhou 350007, China

Sensors 2016, 16(1), 3; https://doi.org/10.3390/s16010003 - 22 Dec 2015

Cited by 26 | Viewed by 5712

Abstract

As wireless sensor network (WSN) is often deployed in a hostile environment, nodes in the networks are prone to large-scale failures, resulting in the network not working normally. In this case, an effective restoration scheme is needed to restore the faulty network timely. [...] Read more.

As wireless sensor network (WSN) is often deployed in a hostile environment, nodes in the networks are prone to large-scale failures, resulting in the network not working normally. In this case, an effective restoration scheme is needed to restore the faulty network timely. Most of existing restoration schemes consider more about the number of deployed nodes or fault tolerance alone, but fail to take into account the fact that network coverage and topology quality are also important to a network. To address this issue, we present two algorithms named Full 2-Connectivity Restoration Algorithm (F2CRA) and Partial 3-Connectivity Restoration Algorithm (P3CRA), which restore a faulty WSN in different aspects. F2CRA constructs the fan-shaped topology structure to reduce the number of deployed nodes, while P3CRA constructs the dual-ring topology structure to improve the fault tolerance of the network. F2CRA is suitable when the restoration cost is given the priority, and P3CRA is suitable when the network quality is considered first. Compared with other algorithms, these two algorithms ensure that the network has stronger fault-tolerant function, larger coverage area and better balanced load after the restoration. Full article

(This article belongs to the Section Sensor Networks)

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23 pages, 4792 KiB

Open AccessArticle

Integration of Directional Antennas in an RSS Fingerprinting-Based Indoor Localization System

by Raúl Guzmán-Quirós^*, Alejandro Martínez-Sala, José Luis Gómez-Tornero and Joan García-Haro

Department of Information and Communication Technologies, Universidad Politécnica de Cartagena, Cartagena 30202, Spain

Sensors 2016, 16(1), 4; https://doi.org/10.3390/s16010004 - 23 Dec 2015

Cited by 23 | Viewed by 8470

Abstract

In this paper, the integration of directional antennas in a room-level received signal strength (RSS) fingerprinting-based indoor localization system (ILS) is studied. The sensor reader (SR), which is in charge of capturing the RSS to infer the tag position, can be attached to [...] Read more.

In this paper, the integration of directional antennas in a room-level received signal strength (RSS) fingerprinting-based indoor localization system (ILS) is studied. The sensor reader (SR), which is in charge of capturing the RSS to infer the tag position, can be attached to an omnidirectional or directional antenna. Unlike commonly-employed omnidirectional antennas, directional antennas can receive a stronger signal from the direction in which they are pointed, resulting in a different RSS distributions in space and, hence, more distinguishable fingerprints. A simulation tool and a system management software have been also developed to control the system and assist the initial antenna deployment, reducing time-consuming costs. A prototype was mounted in a real scenario, with a number of SRs with omnidirectional and directional antennas properly positioned. Different antenna configurations have been studied, evidencing a promising capability of directional antennas to enhance the performance of RSS fingerprinting-based ILS, reducing the number of required SRs and also increasing the localization success. Full article

(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)

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19 pages, 4773 KiB

Open AccessArticle

On the Reliability of a Solitary Wave Based Transducer to Determine the Characteristics of Some Materials

by Wen Deng^1,2,†, Amir Nasrollahi^2,†

, Piervincenzo Rizzo^2,*,† and Kaiyuan Li²

¹ School of Automation, Northwestern Polytechnical University, Xi’an 710072, China

² Laboratory for Nondestructive Evaluation and Structural Health Monitoring Studies, Department of Civil and Environmental Engineering, University of Pittsburgh, 3700 O’Hara Street, 729 Benedum Hall, Pittsburgh, PA 15261, USA

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 5; https://doi.org/10.3390/s16010005 - 23 Dec 2015

Cited by 24 | Viewed by 5255

Abstract

In the study presented in this article we investigated the feasibility and the reliability of a transducer design for the nondestructive evaluation (NDE) of the stiffness of structural materials. The NDE method is based on the propagation of highly nonlinear solitary waves (HNSWs) [...] Read more.

In the study presented in this article we investigated the feasibility and the reliability of a transducer design for the nondestructive evaluation (NDE) of the stiffness of structural materials. The NDE method is based on the propagation of highly nonlinear solitary waves (HNSWs) along a one-dimensional chain of spherical particles that is in contact with the material to be assessed. The chain is part of a built-in system designed and assembled to excite and detect HNSWs, and to exploit the dynamic interaction between the particles and the material to be inspected. This interaction influences the time-of-flight and the amplitude of the solitary pulses reflected at the transducer/material interface. The results of this study show that certain features of the waves are dependent on the modulus of elasticity of the material and that the built-in system is reliable. In the future the proposed NDE method may provide a cost-effective tool for the rapid assessment of materials’ modulus. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 2677 KiB

Open AccessArticle

Application of Carbon-Microsphere-Modified Electrodes for Electrochemistry of Hemoglobin and Electrocatalytic Sensing of Trichloroacetic Acid

by Wen-Cheng Wang, Li-Jun Yan, Fan Shi, Xue-Liang Niu, Guo-Lei Huang, Cai-Juan Zheng^* and Wei Sun

Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, China

Sensors 2016, 16(1), 6; https://doi.org/10.3390/s16010006 - 23 Dec 2015

Cited by 13 | Viewed by 6552

Abstract

By using the hydrothermal method, carbon microspheres (CMS) were fabricated and used for electrode modification. The characteristics of CMS were investigated using various techniques. The biocompatible sensing platform was built by immobilizing hemoglobin (Hb) on the micrometer-sized CMS-modified electrode with a layer of [...] Read more.

By using the hydrothermal method, carbon microspheres (CMS) were fabricated and used for electrode modification. The characteristics of CMS were investigated using various techniques. The biocompatible sensing platform was built by immobilizing hemoglobin (Hb) on the micrometer-sized CMS-modified electrode with a layer of chitosan membrane. On the cyclic voltammogram, a couple of quasi-reversible cathodic and anodic peaks appeared, showing that direct electrochemistry of Hb with the working electrode was achieved. The catalytic reduction peak currents of the bioelectrode to trichloroacetic acid was established in the linear range of 2.0~70.0 mmol·L⁻¹ accompanied by a detection limit of 0.30 mmol·L⁻¹ (3σ). The modified electrode displayed favorable sensitivity, good reproducibility and stability, which suggests that CMS is promising for fabricating third-generation bioelectrochemical sensors. Full article

(This article belongs to the Special Issue Microbial and Enzymatic Biosensors)

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12 pages, 2668 KiB

Open AccessArticle

Parallax-Robust Surveillance Video Stitching

by Botao He^1,* and Shaohua Yu²

¹ School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China

² Wuhan Research Institute of Posts and Telecommunications, Wuhan 430074, China

Sensors 2016, 16(1), 7; https://doi.org/10.3390/s16010007 - 25 Dec 2015

Cited by 49 | Viewed by 10311

Abstract

This paper presents a parallax-robust video stitching technique for timely synchronized surveillance video. An efficient two-stage video stitching procedure is proposed in this paper to build wide Field-of-View (FOV) videos for surveillance applications. In the stitching model calculation stage, we develop a layered [...] Read more.

This paper presents a parallax-robust video stitching technique for timely synchronized surveillance video. An efficient two-stage video stitching procedure is proposed in this paper to build wide Field-of-View (FOV) videos for surveillance applications. In the stitching model calculation stage, we develop a layered warping algorithm to align the background scenes, which is location-dependent and turned out to be more robust to parallax than the traditional global projective warping methods. On the selective seam updating stage, we propose a change-detection based optimal seam selection approach to avert ghosting and artifacts caused by moving foregrounds. Experimental results demonstrate that our procedure can efficiently stitch multi-view videos into a wide FOV video output without ghosting and noticeable seams. Full article

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

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18 pages, 6658 KiB

Open AccessArticle

Proximal Detection of Traces of Energetic Materials with an Eye-Safe UV Raman Prototype Developed for Civil Applications

by Roberto Chirico^1,*, Salvatore Almaviva¹, Francesco Colao¹, Luca Fiorani¹

, Marcello Nuvoli¹, Wenka Schweikert², Frank Schnürer², Luigi Cassioli³, Silvana Grossi³, Daniele Murra⁴, Ivano Menicucci¹, Federico Angelini¹ and Antonio Palucci¹

¹ ENEA, FSN-TECFIS-DIM, Via E. Fermi 45, Frascati (Rome) 00044, Italy

² Fraunhofer Institute for Chemical Technology ICT, Joseph-von-Fraunhofer-Strasse 7, Pfinztal 76327, Germany

³ Italian Air Force, Comando Logistico, 1^Divisione, Centro Sperimentale Volo, Reparto Armamento, Via di Pratica di Mare 45, Pomezia (Rome) 00040, Italy

⁴ ENEA, FSN-FUSPHY-SAD, Via E. Fermi 45, Frascati (Rome) 00044, Italy

Sensors 2016, 16(1), 8; https://doi.org/10.3390/s16010008 - 22 Dec 2015

Cited by 21 | Viewed by 7872

Abstract

A new Raman-based apparatus for proximal detection of energetic materials on people, was developed and tested for the first time. All the optical and optoelectronics components of the apparatus, as well as their optical matching, were carefully chosen and designed to respect international [...] Read more.

A new Raman-based apparatus for proximal detection of energetic materials on people, was developed and tested for the first time. All the optical and optoelectronics components of the apparatus, as well as their optical matching, were carefully chosen and designed to respect international eye-safety regulations. In this way, the apparatus is suitable for civil applications on people in public areas such as airports and metro or railway stations. The acquisition software performs the data analysis in real-time to provide a fast response to the operator. Moreover, it allows for deployment of the apparatus either as a stand alone device or as part of a more sophisticated warning system architecture made up of several sensors. Using polyamide as substrate, the apparatus was able to detect surface densities of ammonium nitrate (AN), 2-methyl-1,3,5-trinitrobenzene (TNT), 3-nitrooxy-2,2-bis(nitrooxymethyl)propyl] nitrate (PETN) and urea nitrate (UN) in the range of 100–1000 μg/cm² at a distance of 6.4 m using each time a single laser pulse of 3 mJ/cm². The limit of detection calculated for AN is 289 μg/cm². AN and UN provided the highest percentages of true positives (>82% for surface densities of 100–400 μg/cm² and fingerprints) followed by TNT and PETN (17%–70% for surface densities of 400–1000 μg/cm² and fingerprints). Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 973 KiB

Open AccessArticle

Service-Aware Clustering: An Energy-Efficient Model for the Internet-of-Things

by Antoine Bagula^1,*

, Ademola Philip Abidoye¹ and Guy-Alain Lusilao Zodi²

¹ Intelligent Systems and Advanced Telecommunication Laboratory, Department of Computer Science, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa

² Department of Computer Science, Namibia University of Science and Technology (NUST), Private Bag 13888, Windhoek 9000, Namibia

Sensors 2016, 16(1), 9; https://doi.org/10.3390/s16010009 - 23 Dec 2015

Cited by 27 | Viewed by 6634

Abstract

Current generation wireless sensor routing algorithms and protocols have been designed based on a myopic routing approach, where the motes are assumed to have the same sensing and communication capabilities. Myopic routing is not a natural fit for the IoT, as it may [...] Read more.

Current generation wireless sensor routing algorithms and protocols have been designed based on a myopic routing approach, where the motes are assumed to have the same sensing and communication capabilities. Myopic routing is not a natural fit for the IoT, as it may lead to energy imbalance and subsequent short-lived sensor networks, routing the sensor readings over the most service-intensive sensor nodes, while leaving the least active nodes idle. This paper revisits the issue of energy efficiency in sensor networks to propose a clustering model where sensor devices’ service delivery is mapped into an energy awareness model, used to design a clustering algorithm that finds service-aware clustering (SAC) configurations in IoT settings. The performance evaluation reveals the relative energy efficiency of the proposed SAC algorithm compared to related routing algorithms in terms of energy consumption, the sensor nodes’ life span and its traffic engineering efficiency in terms of throughput and delay. These include the well-known low energy adaptive clustering hierarchy (LEACH) and LEACH-centralized (LEACH-C) algorithms, as well as the most recent algorithms, such as DECSA and MOCRN. Full article

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

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20 pages, 2602 KiB

Open AccessArticle

A Novel Time-Varying Spectral Filtering Algorithm for Reconstruction of Motion Artifact Corrupted Heart Rate Signals During Intense Physical Activities Using a Wearable Photoplethysmogram Sensor

by Seyed M. A. Salehizadeh^1,*, Duy Dao¹, Jeffrey Bolkhovsky¹, Chae Cho¹, Yitzhak Mendelson² and Ki H. Chon^1,*

¹ Department of Biomedical Engineering, University of Connecticut, Storrs, CT 06269, USA

² Department of Biomedical Engineering, Worcester Polytechnic Institution, Worcester, MA 01609, USA

Sensors 2016, 16(1), 10; https://doi.org/10.3390/s16010010 - 23 Dec 2015

Cited by 143 | Viewed by 11307

Abstract

Accurate estimation of heart rates from photoplethysmogram (PPG) signals during intense physical activity is a very challenging problem. This is because strenuous and high intensity exercise can result in severe motion artifacts in PPG signals, making accurate heart rate (HR) estimation difficult. In [...] Read more.

Accurate estimation of heart rates from photoplethysmogram (PPG) signals during intense physical activity is a very challenging problem. This is because strenuous and high intensity exercise can result in severe motion artifacts in PPG signals, making accurate heart rate (HR) estimation difficult. In this study we investigated a novel technique to accurately reconstruct motion-corrupted PPG signals and HR based on time-varying spectral analysis. The algorithm is called Spectral filter algorithm for Motion Artifacts and heart rate reconstruction (SpaMA). The idea is to calculate the power spectral density of both PPG and accelerometer signals for each time shift of a windowed data segment. By comparing time-varying spectra of PPG and accelerometer data, those frequency peaks resulting from motion artifacts can be distinguished from the PPG spectrum. The SpaMA approach was applied to three different datasets and four types of activities: (1) training datasets from the 2015 IEEE Signal Process. Cup Database recorded from 12 subjects while performing treadmill exercise from 1 km/h to 15 km/h; (2) test datasets from the 2015 IEEE Signal Process. Cup Database recorded from 11 subjects while performing forearm and upper arm exercise. (3) Chon Lab dataset including 10 min recordings from 10 subjects during treadmill exercise. The ECG signals from all three datasets provided the reference HRs which were used to determine the accuracy of our SpaMA algorithm. The performance of the SpaMA approach was calculated by computing the mean absolute error between the estimated HR from the PPG and the reference HR from the ECG. The average estimation errors using our method on the first, second and third datasets are 0.89, 1.93 and 1.38 beats/min respectively, while the overall error on all 33 subjects is 1.86 beats/min and the performance on only treadmill experiment datasets (22 subjects) is 1.11 beats/min. Moreover, it was found that dynamics of heart rate variability can be accurately captured using the algorithm where the mean Pearson’s correlation coefficient between the power spectral densities of the reference and the reconstructed heart rate time series was found to be 0.98. These results show that the SpaMA method has a potential for PPG-based HR monitoring in wearable devices for fitness tracking and health monitoring during intense physical activities. Full article

(This article belongs to the Special Issue Wearable Sensors)

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14 pages, 8318 KiB

Open AccessArticle

Segmentation of a Vibro-Shock Cantilever-Type Piezoelectric Energy Harvester Operating in Higher Transverse Vibration Modes

by Darius Zizys^1,*

, Rimvydas Gaidys¹, Rolanas Dauksevicius², Vytautas Ostasevicius² and Vytautas Daniulaitis³

¹ Faculty of Mechanical Engineering and Design, Kaunas University of Technology, Studentu 56, Kaunas LT-51368, Lithuania

² Institute of Mechatronics, Kaunas University of Technology, Studentu 56-123, Kaunas LT-51368, Lithuania

³ Faculty of Informatics, Kaunas University of Technology, Studentu 50, Kaunas LT-51368, Lithuania

Sensors 2016, 16(1), 11; https://doi.org/10.3390/s16010011 - 23 Dec 2015

Cited by 23 | Viewed by 6389

Abstract

The piezoelectric transduction mechanism is a common vibration-to-electric energy harvesting approach. Piezoelectric energy harvesters are typically mounted on a vibrating host structure, whereby alternating voltage output is generated by a dynamic strain field. A design target in this case is to match the [...] Read more.

The piezoelectric transduction mechanism is a common vibration-to-electric energy harvesting approach. Piezoelectric energy harvesters are typically mounted on a vibrating host structure, whereby alternating voltage output is generated by a dynamic strain field. A design target in this case is to match the natural frequency of the harvester to the ambient excitation frequency for the device to operate in resonance mode, thus significantly increasing vibration amplitudes and, as a result, energy output. Other fundamental vibration modes have strain nodes, where the dynamic strain field changes sign in the direction of the cantilever length. The paper reports on a dimensionless numerical transient analysis of a cantilever of a constant cross-section and an optimally-shaped cantilever with the objective to accurately predict the position of a strain node. Total effective strain produced by both cantilevers segmented at the strain node is calculated via transient analysis and compared to the strain output produced by the cantilevers segmented at strain nodes obtained from modal analysis, demonstrating a 7% increase in energy output. Theoretical results were experimentally verified by using open-circuit voltage values measured for the cantilevers segmented at optimal and suboptimal segmentation lines. Full article

(This article belongs to the Section Sensor Networks)

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13 pages, 1545 KiB

Open AccessArticle

Robust Foot Clearance Estimation Based on the Integration of Foot-Mounted IMU Acceleration Data

by Mourad Benoussaad^1,*,†, Benoît Sijobert¹, Katja Mombaur² and Christine Azevedo Coste¹

¹ INRIA, LIRMM, Rue Saint Priest, Montpellier 34000, France

² ORB, IWR, University of Heidelberg, Heidelberg 69117, Germany

^† Current Address: LGP Lab, Tarbes 65000, France

Sensors 2016, 16(1), 12; https://doi.org/10.3390/s16010012 - 23 Dec 2015

Cited by 53 | Viewed by 12537

Abstract

This paper introduces a method for the robust estimation of foot clearance during walking, using a single inertial measurement unit (IMU) placed on the subject’s foot. The proposed solution is based on double integration and drift cancellation of foot acceleration signals. The method [...] Read more.

This paper introduces a method for the robust estimation of foot clearance during walking, using a single inertial measurement unit (IMU) placed on the subject’s foot. The proposed solution is based on double integration and drift cancellation of foot acceleration signals. The method is insensitive to misalignment of IMU axes with respect to foot axes. Details are provided regarding calibration and signal processing procedures. Experimental validation was performed on 10 healthy subjects under three walking conditions: normal, fast and with obstacles. Foot clearance estimation results were compared to measurements from an optical motion capture system. The mean error between them is significantly less than 15 % under the various walking conditions. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 6622 KiB

Open AccessArticle

Underwater 3D Surface Measurement Using Fringe Projection Based Scanning Devices

by Christian Bräuer-Burchardt^1,*, Matthias Heinze¹, Ingo Schmidt¹, Peter Kühmstedt¹ and Gunther Notni^1,2

¹ Fraunhofer Institute Applied Optics and Precision Engineering, Albert-Einstein-Str. 7, D-07745 Jena, Germany

² Technical University Ilmenau, Ehrenbergstraße 29, D-98693 Ilmenau, Germany

Sensors 2016, 16(1), 13; https://doi.org/10.3390/s16010013 - 23 Dec 2015

Cited by 31 | Viewed by 9509

Abstract

In this work we show the principle of optical 3D surface measurements based on the fringe projection technique for underwater applications. The challenges of underwater use of this technique are shown and discussed in comparison with the classical application. We describe an extended [...] Read more.

In this work we show the principle of optical 3D surface measurements based on the fringe projection technique for underwater applications. The challenges of underwater use of this technique are shown and discussed in comparison with the classical application. We describe an extended camera model which takes refraction effects into account as well as a proposal of an effective, low-effort calibration procedure for underwater optical stereo scanners. This calibration technique combines a classical air calibration based on the pinhole model with ray-based modeling and requires only a few underwater recordings of an object of known length and a planar surface. We demonstrate a new underwater 3D scanning device based on the fringe projection technique. It has a weight of about 10 kg and the maximal water depth for application of the scanner is 40 m. It covers an underwater measurement volume of 250 mm × 200 mm × 120 mm. The surface of the measurement objects is captured with a lateral resolution of 150 μm in a third of a second. Calibration evaluation results are presented and examples of first underwater measurements are given. Full article

(This article belongs to the Special Issue Sensors and Techniques for 3D Object Modeling in Underwater Environments)

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8 pages, 2930 KiB

Open AccessArticle

Novel H⁺-Ion Sensor Based on a Gated Lateral BJT Pair

by Heng Yuan^1,*, Jixing Zhang¹, Chuangui Cao¹, Gangyuan Zhang¹ and Shaoda Zhang^2,*

¹ Science and Technology on Inertial Laboratory, Beihang University, No. 37 Xueyuan Road, Beijing 100191, China

² Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, No. 422 South Siming Road, Xiamen 361005, China

Sensors 2016, 16(1), 14; https://doi.org/10.3390/s16010014 - 23 Dec 2015

Cited by 4 | Viewed by 5424

Abstract

An H⁺-ion sensor based on a gated lateral bipolar junction transistor (BJT) pair that can operate without the classical reference electrode is proposed. The device is a special type of ion-sensitive field-effect transistor (ISFET). Classical ISFETs have the advantage of miniaturization, [...] Read more.

An H⁺-ion sensor based on a gated lateral bipolar junction transistor (BJT) pair that can operate without the classical reference electrode is proposed. The device is a special type of ion-sensitive field-effect transistor (ISFET). Classical ISFETs have the advantage of miniaturization, but they are difficult to fabricate by a single fabrication process because of the bulky and brittle reference electrode materials. Moreover, the reference electrodes need to be separated from the sensor device in some cases. The proposed device is composed of two gated lateral BJT components, one of which had a silicide layer while the other was without the layer. The two components were operated under the metal-oxide semiconductor field-effect transistor (MOSFET)-BJT hybrid mode, which can be controlled by emitter voltage and base current. Buffer solutions with different pH values were used as the sensing targets to verify the characteristics of the proposed device. Owing to their different sensitivities, both components could simultaneously detect the H⁺-ion concentration and function as a reference to each other. Per the experimental results, the sensitivity of the proposed device was found to be approximately 0.175 μA/pH. This experiment demonstrates enormous potential to lower the cost of the ISFET-based sensor technology. Full article

(This article belongs to the Section Chemical Sensors)

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18 pages, 7159 KiB

Open AccessArticle

Corrosion Assessment of Steel Bars Used in Reinforced Concrete Structures by Means of Eddy Current Testing

by Naasson P. De Alcantara, Jr.^*, Felipe M. Da Silva, Mateus T. Guimarães and Matheus D. Pereira

Department of Electrical Engineering, São Paulo State University—Unesp, Bauru 17033-360, Brazil

Sensors 2016, 16(1), 15; https://doi.org/10.3390/s16010015 - 24 Dec 2015

Cited by 43 | Viewed by 10425

Abstract

This paper presents a theoretical and experimental study on the use of Eddy Current Testing (ECT) to evaluate corrosion processes in steel bars used in reinforced concrete structures. The paper presents the mathematical basis of the ECT sensor built by the authors; followed [...] Read more.

This paper presents a theoretical and experimental study on the use of Eddy Current Testing (ECT) to evaluate corrosion processes in steel bars used in reinforced concrete structures. The paper presents the mathematical basis of the ECT sensor built by the authors; followed by a finite element analysis. The results obtained in the simulations are compared with those obtained in experimental tests performed by the authors. Effective resistances and inductances; voltage drops and phase angles of wound coil are calculated using both; simulated and experimental data; and demonstrate a strong correlation. The production of samples of corroded steel bars; by using an impressed current technique is also presented. The authors performed experimental tests in the laboratory using handmade sensors; and the corroded samples. In the tests four gauges; with five levels of loss-of-mass references for each one were used. The results are analyzed in the light of the loss-of-mass and show a strong linear behavior for the analyzed parameters. The conclusions emphasize the feasibility of the proposed technique and highlight opportunities for future works. Full article

(This article belongs to the Section Physical Sensors)

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38 pages, 5649 KiB

Open AccessArticle

Trust and Privacy Solutions Based on Holistic Service Requirements

by José Antonio Sánchez Alcón^*

, Lourdes López^†

, José-Fernán Martínez^† and Gregorio Rubio Cifuentes^†

¹ Centro de Investigación en Tecnologías Software y Sistemas Multimedia para la Sostenibilidad (CITSEM), Campus Sur Universidad Politécnica de Madrid (UPM), Ctra. de Valencia, km. 7. 28031 Madrid, Spain

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 16; https://doi.org/10.3390/s16010016 - 24 Dec 2015

Cited by 10 | Viewed by 7128

Abstract

The products and services designed for Smart Cities provide the necessary tools to improve the management of modern cities in a more efficient way. These tools need to gather citizens’ information about their activity, preferences, habits, etc. opening up the possibility of tracking [...] Read more.

The products and services designed for Smart Cities provide the necessary tools to improve the management of modern cities in a more efficient way. These tools need to gather citizens’ information about their activity, preferences, habits, etc. opening up the possibility of tracking them. Thus, privacy and security policies must be developed in order to satisfy and manage the legislative heterogeneity surrounding the services provided and comply with the laws of the country where they are provided. This paper presents one of the possible solutions to manage this heterogeneity, bearing in mind these types of networks, such as Wireless Sensor Networks, have important resource limitations. A knowledge and ontology management system is proposed to facilitate the collaboration between the business, legal and technological areas. This will ease the implementation of adequate specific security and privacy policies for a given service. All these security and privacy policies are based on the information provided by the deployed platforms and by expert system processing. Full article

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

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19 pages, 6439 KiB

Open AccessArticle

HyMoTrack: A Mobile AR Navigation System for Complex Indoor Environments

by Georg Gerstweiler^*,†, Emanuel Vonach^† and Hannes Kaufmann^†

¹ Institute of Software Technology and Interactive Systems, Vienna University of Technology, Favoritenstrasse 9-11-188/2, Vienna 1040, Austria

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 17; https://doi.org/10.3390/s16010017 - 24 Dec 2015

Cited by 58 | Viewed by 12186

Abstract

Navigating in unknown big indoor environments with static 2D maps is a challenge, especially when time is a critical factor. In order to provide a mobile assistant, capable of supporting people while navigating in indoor locations, an accurate and reliable localization system is [...] Read more.

Navigating in unknown big indoor environments with static 2D maps is a challenge, especially when time is a critical factor. In order to provide a mobile assistant, capable of supporting people while navigating in indoor locations, an accurate and reliable localization system is required in almost every corner of the building. We present a solution to this problem through a hybrid tracking system specifically designed for complex indoor spaces, which runs on mobile devices like smartphones or tablets. The developed algorithm only uses the available sensors built into standard mobile devices, especially the inertial sensors and the RGB camera. The combination of multiple optical tracking technologies, such as 2D natural features and features of more complex three-dimensional structures guarantees the robustness of the system. All processing is done locally and no network connection is needed. State-of-the-art indoor tracking approaches use mainly radio-frequency signals like Wi-Fi or Bluetooth for localizing a user. In contrast to these approaches, the main advantage of the developed system is the capability of delivering a continuous 3D position and orientation of the mobile device with centimeter accuracy. This makes it usable for localization and 3D augmentation purposes, e.g. navigation tasks or location-based information visualization. Full article

(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)

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55 pages, 10407 KiB

Open AccessReview

Inertial Sensor Technology for Elite Swimming Performance Analysis: A Systematic Review

by Robert Mooney^1,2, Gavin Corley^1,2, Alan Godfrey³, Leo R Quinlan^4,5,*

and Gearóid ÓLaighin^1,2,5

¹ Electrical & Electronic Engineering, School of Engineering & Informatics, NUI Galway, University Road, Galway, Ireland

² Bioelectronics Research Cluster, National Centre for Biomedical Engineering Science, NUI Galway, University Road, Galway, Ireland

³ Institute for Neuroscience, Newcastle University, Newcastle upon Tyne, Tyne and Wear NE1 7RU, UK

⁴ Physiology, School of Medicine, NUI Galway, University Road, Galway, Ireland

⁵ CÚRAM (SFI Centre for Research in Medical Devices), NUI Galway, University Road, Galway, Ireland

Sensors 2016, 16(1), 18; https://doi.org/10.3390/s16010018 - 25 Dec 2015

Cited by 115 | Viewed by 22071

Abstract

Technical evaluation of swimming performance is an essential factor of elite athletic preparation. Novel methods of analysis, incorporating body worn inertial sensors (i.e., Microelectromechanical systems, or MEMS, accelerometers and gyroscopes), have received much attention recently from both research and commercial communities [...] Read more.

Technical evaluation of swimming performance is an essential factor of elite athletic preparation. Novel methods of analysis, incorporating body worn inertial sensors (i.e., Microelectromechanical systems, or MEMS, accelerometers and gyroscopes), have received much attention recently from both research and commercial communities as an alternative to video-based approaches. This technology may allow for improved analysis of stroke mechanics, race performance and energy expenditure, as well as real-time feedback to the coach, potentially enabling more efficient, competitive and quantitative coaching. The aim of this paper is to provide a systematic review of the literature related to the use of inertial sensors for the technical analysis of swimming performance. This paper focuses on providing an evaluation of the accuracy of different feature detection algorithms described in the literature for the analysis of different phases of swimming, specifically starts, turns and free-swimming. The consequences associated with different sensor attachment locations are also considered for both single and multiple sensor configurations. Additional information such as this should help practitioners to select the most appropriate systems and methods for extracting the key performance related parameters that are important to them for analysing their swimmers’ performance and may serve to inform both applied and research practices. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 4121 KiB

Open AccessArticle

Optical Indoor Positioning System Based on TFT Technology

by István Gőzse

Institute for Computer Science and Control, Hungarian Academy of Science, Kende St. 13–17, 1111 Budapest, Hungary

Sensors 2016, 16(1), 19; https://doi.org/10.3390/s16010019 - 24 Dec 2015

Cited by 5 | Viewed by 5541

Abstract

A novel indoor positioning system is presented in the paper. Similarly to the camera-based solutions, it is based on visual detection, but it conceptually differs from the classical approaches. First, the objects are marked by LEDs, and second, a special sensing unit is [...] Read more.

A novel indoor positioning system is presented in the paper. Similarly to the camera-based solutions, it is based on visual detection, but it conceptually differs from the classical approaches. First, the objects are marked by LEDs, and second, a special sensing unit is applied, instead of a camera, to track the motion of the markers. This sensing unit realizes a modified pinhole camera model, where the light-sensing area is fixed and consists of a small number of sensing elements (photodiodes), and it is the hole that can be moved. The markers are tracked by controlling the motion of the hole, such that the light of the LEDs always hits the photodiodes. The proposed concept has several advantages: Apart from its low computational demands, it is insensitive to the disturbing ambient light. Moreover, as every component of the system can be realized by simple and inexpensive elements, the overall cost of the system can be kept low. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 1622 KiB

Open AccessArticle

Mutual Authentication Scheme in Secure Internet of Things Technology for Comfortable Lifestyle

by Namje Park^1,*

and Namhi Kang^2,*

¹ Department of Computer Education, Teachers College, Jeju National University, 61 Iljudong-ro, Jeju-si, Jeju Special Self-Governing Province 690-781, Korea

² Digital Media Department, Duksung Women’s University, Ssangmoon-Dong 419, Dobong-Gu, Seoul 132-714, Korea

Sensors 2016, 16(1), 20; https://doi.org/10.3390/s16010020 - 24 Dec 2015

Cited by 121 | Viewed by 9955

Abstract

The Internet of Things (IoT), which can be regarded as an enhanced version of machine-to-machine communication technology, was proposed to realize intelligent thing-to-thing communications by utilizing the Internet connectivity. In the IoT, “things” are generally heterogeneous and resource constrained. In addition, such things [...] Read more.

The Internet of Things (IoT), which can be regarded as an enhanced version of machine-to-machine communication technology, was proposed to realize intelligent thing-to-thing communications by utilizing the Internet connectivity. In the IoT, “things” are generally heterogeneous and resource constrained. In addition, such things are connected to each other over low-power and lossy networks. In this paper, we propose an inter-device authentication and session-key distribution system for devices with only encryption modules. In the proposed system, unlike existing sensor-network environments where the key distribution center distributes the key, each sensor node is involved with the generation of session keys. In addition, in the proposed scheme, the performance is improved so that the authenticated device can calculate the session key in advance. The proposed mutual authentication and session-key distribution system can withstand replay attacks, man-in-the-middle attacks, and wiretapped secret-key attacks. Full article

(This article belongs to the Section Sensor Networks)

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26 pages, 379 KiB

Open AccessArticle

Classifier Subset Selection for the Stacked Generalization Method Applied to Emotion Recognition in Speech

by Aitor Álvarez^1,*, Basilio Sierra², Andoni Arruti²

, Juan-Miguel López-Gil² and Nestor Garay-Vitoria²

¹ Vicomtech-IK4. Human Speech and Language Technologies Department, Paseo Mikeletegi 57, Parque Científico y Tecnológico de Gipuzkoa, 20009 Donostia-San Sebastián, Spain

² University of the Basque Country (UPV/EHU), Paseo de Manuel Lardizabal 1, 20018 Donostia-San Sebastián, Spain

Sensors 2016, 16(1), 21; https://doi.org/10.3390/s16010021 - 25 Dec 2015

Cited by 17 | Viewed by 7699

Abstract

In this paper, a new supervised classification paradigm, called classifier subset selection for stacked generalization (CSS stacking), is presented to deal with speech emotion recognition. The new approach consists of an improvement of a bi-level multi-classifier system known as stacking generalization by means [...] Read more.

In this paper, a new supervised classification paradigm, called classifier subset selection for stacked generalization (CSS stacking), is presented to deal with speech emotion recognition. The new approach consists of an improvement of a bi-level multi-classifier system known as stacking generalization by means of an integration of an estimation of distribution algorithm (EDA) in the first layer to select the optimal subset from the standard base classifiers. The good performance of the proposed new paradigm was demonstrated over different configurations and datasets. First, several CSS stacking classifiers were constructed on the RekEmozio dataset, using some specific standard base classifiers and a total of 123 spectral, quality and prosodic features computed using in-house feature extraction algorithms. These initial CSS stacking classifiers were compared to other multi-classifier systems and the employed standard classifiers built on the same set of speech features. Then, new CSS stacking classifiers were built on RekEmozio using a different set of both acoustic parameters (extended version of the Geneva Minimalistic Acoustic Parameter Set (eGeMAPS)) and standard classifiers and employing the best meta-classifier of the initial experiments. The performance of these two CSS stacking classifiers was evaluated and compared. Finally, the new paradigm was tested on the well-known Berlin Emotional Speech database. We compared the performance of single, standard stacking and CSS stacking systems using the same parametrization of the second phase. All of the classifications were performed at the categorical level, including the six primary emotions plus the neutral one. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 784 KiB

Open AccessArticle

Sedentary Behaviour Profiling of Office Workers: A Sensitivity Analysis of Sedentary Cut-Points

by Simone T. Boerema^1,2,*

, Gerard B. Essink^1,2, Thijs M. Tönis^1,2

, Lex Van Velsen^1,2 and Hermie J. Hermens^1,2

¹ Telemedicine Group, Roessingh Research and Development, P.O. Box 310, 7500 AH, Enschede, The Netherlands

² Telemedicine Group, Faculty of Electrical Engineering, Mathematics and Computer Science, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands

Sensors 2016, 16(1), 22; https://doi.org/10.3390/s16010022 - 25 Dec 2015

Cited by 9 | Viewed by 6074

Abstract

Measuring sedentary behaviour and physical activity with wearable sensors provides detailed information on activity patterns and can serve health interventions. At the basis of activity analysis stands the ability to distinguish sedentary from active time. As there is no consensus regarding the optimal [...] Read more.

Measuring sedentary behaviour and physical activity with wearable sensors provides detailed information on activity patterns and can serve health interventions. At the basis of activity analysis stands the ability to distinguish sedentary from active time. As there is no consensus regarding the optimal cut-point for classifying sedentary behaviour, we studied the consequences of using different cut-points for this type of analysis. We conducted a battery of sitting and walking activities with 14 office workers, wearing the Promove 3D activity sensor to determine the optimal cut-point (in counts per minute (m·s⁻²)) for classifying sedentary behaviour. Then, 27 office workers wore the sensor for five days. We evaluated the sensitivity of five sedentary pattern measures for various sedentary cut-points and found an optimal cut-point for sedentary behaviour of 1660 × 10⁻³ m·s⁻². Total sedentary time was not sensitive to cut-point changes within ±10% of this optimal cut-point; other sedentary pattern measures were not sensitive to changes within the ±20% interval. The results from studies analyzing sedentary patterns, using different cut-points, can be compared within these boundaries. Furthermore, commercial, hip-worn activity trackers can implement feedback and interventions on sedentary behaviour patterns, using these cut-points. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 14170 KiB

Open AccessArticle

Moving Object Detection on a Vehicle Mounted Back-Up Camera

by Dong-Sun Kim^*

and Jinsan Kwon

Embedded Software Convergence Research Center, Korea Electronics Technology Institute, Saenari-ro 25, Bundang-gu, Seongnam-si, Gyeonggi-do 13509, Korea

Sensors 2016, 16(1), 23; https://doi.org/10.3390/s16010023 - 25 Dec 2015

Cited by 24 | Viewed by 9744

Abstract

In the detection of moving objects from vision sources one usually assumes that the scene has been captured by stationary cameras. In case of backing up a vehicle, however, the camera mounted on the vehicle moves according to the vehicle’s movement, resulting in [...] Read more.

In the detection of moving objects from vision sources one usually assumes that the scene has been captured by stationary cameras. In case of backing up a vehicle, however, the camera mounted on the vehicle moves according to the vehicle’s movement, resulting in ego-motions on the background. This results in mixed motion in the scene, and makes it difficult to distinguish between the target objects and background motions. Without further treatments on the mixed motion, traditional fixed-viewpoint object detection methods will lead to many false-positive detection results. In this paper, we suggest a procedure to be used with the traditional moving object detection methods relaxing the stationary cameras restriction, by introducing additional steps before and after the detection. We also decribe the implementation as a FPGA platform along with the algorithm. The target application of this suggestion is use with a road vehicle’s rear-view camera systems. Full article

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

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24 pages, 6207 KiB

Open AccessArticle

Sensor Fusion Based Model for Collision Free Mobile Robot Navigation

by Marwah Almasri^*, Khaled Elleithy^*

and Abrar Alajlan^*

Computer Science and Engineering Department, University of Bridgeport, 126 Park Ave, Bridgeport, CT 06604, USA

Sensors 2016, 16(1), 24; https://doi.org/10.3390/s16010024 - 26 Dec 2015

Cited by 42 | Viewed by 11561

Abstract

Autonomous mobile robots have become a very popular and interesting topic in the last decade. Each of them are equipped with various types of sensors such as GPS, camera, infrared and ultrasonic sensors. These sensors are used to observe the surrounding environment. However, [...] Read more.

Autonomous mobile robots have become a very popular and interesting topic in the last decade. Each of them are equipped with various types of sensors such as GPS, camera, infrared and ultrasonic sensors. These sensors are used to observe the surrounding environment. However, these sensors sometimes fail and have inaccurate readings. Therefore, the integration of sensor fusion will help to solve this dilemma and enhance the overall performance. This paper presents a collision free mobile robot navigation based on the fuzzy logic fusion model. Eight distance sensors and a range finder camera are used for the collision avoidance approach where three ground sensors are used for the line or path following approach. The fuzzy system is composed of nine inputs which are the eight distance sensors and the camera, two outputs which are the left and right velocities of the mobile robot’s wheels, and 24 fuzzy rules for the robot’s movement. Webots Pro simulator is used for modeling the environment and the robot. The proposed methodology, which includes the collision avoidance based on fuzzy logic fusion model and line following robot, has been implemented and tested through simulation and real time experiments. Various scenarios have been presented with static and dynamic obstacles using one robot and two robots while avoiding obstacles in different shapes and sizes. Full article

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

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13 pages, 651 KiB

Open AccessArticle

A Novel Method of Multi-Information Acquisition for Electromagnetic Flow Meters

by Wenhua Cui^*, Bin Li^*, Jie Chen and Xinwei Li

School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200072, China

Sensors 2016, 16(1), 25; https://doi.org/10.3390/s16010025 - 26 Dec 2015

Cited by 6 | Viewed by 6036

Abstract

In this paper, a novel method is proposed for multi-information acquisition from the electromagnetic flow meter, using magnetic excitation to measure the fluid velocity and electrochemistry impedance spectroscopy (EIS) for both the fluid quality and the contamination level of the transducer. The impedance [...] Read more.

In this paper, a novel method is proposed for multi-information acquisition from the electromagnetic flow meter, using magnetic excitation to measure the fluid velocity and electrochemistry impedance spectroscopy (EIS) for both the fluid quality and the contamination level of the transducer. The impedance spectra of the transducer are measured with an additional electrical stimulus in series with the electrode measurement loop. The series connection mode instead of the parallel one improves the signal-to-noise ratio (SNR) of the fluid velocity measurement and offers a wide range of impedance measurements by using a sample capacitance. In addition, a multi-frequency synchronous excitation source is synthesized based on the method of dual-base power sequences for fast EIS measurement. The conductivity measurements in the range of 1.7 μS/cm–2 mS/cm showed a relatively high accuracy with a measurement error of 5%, and the electrode adhesion detection on both with coating and no coating showed the ability of the qualitative determination of the electrode adhesion, which validated the feasibility of the multi-information acquisition method for the electromagnetic flow meter (EMFM). Full article

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

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22 pages, 3581 KiB

Open AccessArticle

A Multi-Hop Energy Neutral Clustering Algorithm for Maximizing Network Information Gathering in Energy Harvesting Wireless Sensor Networks

by Liu Yang¹

, Yinzhi Lu², Yuanchang Zhong^1,*, Xuegang Wu¹

and Simon X. Yang³

¹ College of Communication Engineering, Chongqing University, Chongqing 400044, China

² School of Electronic Information Engineering, Yangtze Normal University, Chongqing 408100, China

³ The Advanced Robotics and Intelligent Systems Laboratory, School of Engineering, University of Guelph, Guelph, ON N1G2W1, Canada

Sensors 2016, 16(1), 26; https://doi.org/10.3390/s16010026 - 26 Dec 2015

Cited by 22 | Viewed by 7147

Abstract

Energy resource limitation is a severe problem in traditional wireless sensor networks (WSNs) because it restricts the lifetime of network. Recently, the emergence of energy harvesting techniques has brought with them the expectation to overcome this problem. In particular, it is possible for [...] Read more.

Energy resource limitation is a severe problem in traditional wireless sensor networks (WSNs) because it restricts the lifetime of network. Recently, the emergence of energy harvesting techniques has brought with them the expectation to overcome this problem. In particular, it is possible for a sensor node with energy harvesting abilities to work perpetually in an Energy Neutral state. In this paper, a Multi-hop Energy Neutral Clustering (MENC) algorithm is proposed to construct the optimal multi-hop clustering architecture in energy harvesting WSNs, with the goal of achieving perpetual network operation. All cluster heads (CHs) in the network act as routers to transmit data to base station (BS) cooperatively by a multi-hop communication method. In addition, by analyzing the energy consumption of intra- and inter-cluster data transmission, we give the energy neutrality constraints. Under these constraints, every sensor node can work in an energy neutral state, which in turn provides perpetual network operation. Furthermore, the minimum network data transmission cycle is mathematically derived using convex optimization techniques while the network information gathering is maximal. Simulation results show that our protocol can achieve perpetual network operation, so that the consistent data delivery is guaranteed. In addition, substantial improvements on the performance of network throughput are also achieved as compared to the famous traditional clustering protocol LEACH and recent energy harvesting aware clustering protocols. Full article

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

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14 pages, 8276 KiB

Open AccessArticle

A Fast Multiple Sampling Method for Low-Noise CMOS Image Sensors With Column-Parallel 12-bit SAR ADCs

by Min-Kyu Kim, Seong-Kwan Hong and Oh-Kyong Kwon^*

Department of Electronics and Computer Engineering, Hanyang University, Seoul 133-791, Korea

Sensors 2016, 16(1), 27; https://doi.org/10.3390/s16010027 - 26 Dec 2015

Cited by 10 | Viewed by 10897

Abstract

This paper presents a fast multiple sampling method for low-noise CMOS image sensor (CIS) applications with column-parallel successive approximation register analog-to-digital converters (SAR ADCs). The 12-bit SAR ADC using the proposed multiple sampling method decreases the A/D conversion time by repeatedly converting a [...] Read more.

This paper presents a fast multiple sampling method for low-noise CMOS image sensor (CIS) applications with column-parallel successive approximation register analog-to-digital converters (SAR ADCs). The 12-bit SAR ADC using the proposed multiple sampling method decreases the A/D conversion time by repeatedly converting a pixel output to 4-bit after the first 12-bit A/D conversion, reducing noise of the CIS by one over the square root of the number of samplings. The area of the 12-bit SAR ADC is reduced by using a 10-bit capacitor digital-to-analog converter (DAC) with four scaled reference voltages. In addition, a simple up/down counter-based digital processing logic is proposed to perform complex calculations for multiple sampling and digital correlated double sampling. To verify the proposed multiple sampling method, a 256 × 128 pixel array CIS with 12-bit SAR ADCs was fabricated using 0.18 μm CMOS process. The measurement results shows that the proposed multiple sampling method reduces each A/D conversion time from 1.2 μs to 0.45 μs and random noise from 848.3 μV to 270.4 μV, achieving a dynamic range of 68.1 dB and an SNR of 39.2 dB. Full article

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

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23 pages, 1361 KiB

Open AccessArticle

Mission Planning and Decision Support for Underwater Glider Networks: A Sampling on-Demand Approach

by Gabriele Ferri^1,*, Marco Cococcioni² and Alberto Alvarez¹

¹ Research Department, NATO STO Centre for Maritime Research and Experimentation (CMRE), Viale San Bartolomeo 400, 19126 La Spezia, Italy

² Dipartimento di Ingegneria dell’Informazione, University of Pisa, Largo Lucio Lazzarino 1, 56122 Pisa, Italy

Sensors 2016, 16(1), 28; https://doi.org/10.3390/s16010028 - 26 Dec 2015

Cited by 27 | Viewed by 7824

Abstract

This paper describes an optimal sampling approach to support glider fleet operators and marine scientists during the complex task of planning the missions of fleets of underwater gliders. Optimal sampling, which has gained considerable attention in the last decade, consists in planning the [...] Read more.

This paper describes an optimal sampling approach to support glider fleet operators and marine scientists during the complex task of planning the missions of fleets of underwater gliders. Optimal sampling, which has gained considerable attention in the last decade, consists in planning the paths of gliders to minimize a specific criterion pertinent to the phenomenon under investigation. Different criteria (e.g., A, G, or E optimality), used in geosciences to obtain an optimum design, lead to different sampling strategies. In particular, the A criterion produces paths for the gliders that minimize the overall level of uncertainty over the area of interest. However, there are commonly operative situations in which the marine scientists may prefer not to minimize the overall uncertainty of a certain area, but instead they may be interested in achieving an acceptable uncertainty sufficient for the scientific or operational needs of the mission. We propose and discuss here an approach named sampling on-demand that explicitly addresses this need. In our approach the user provides an objective map, setting both the amount and the geographic distribution of the uncertainty to be achieved after assimilating the information gathered by the fleet. A novel optimality criterion, called A η , is proposed and the resulting minimization problem is solved by using a Simulated Annealing based optimizer that takes into account the constraints imposed by the glider navigation features, the desired geometry of the paths and the problems of reachability caused by ocean currents. This planning strategy has been implemented in a Matlab toolbox called SoDDS (Sampling on-Demand and Decision Support). The tool is able to automatically download the ocean fields data from MyOcean repository and also provides graphical user interfaces to ease the input process of mission parameters and targets. The results obtained by running SoDDS on three different scenarios are provided and show that SoDDS, which is currently used at NATO STO Centre for Maritime Research and Experimentation (CMRE), can represent a step forward towards a systematic mission planning of glider fleets, dramatically reducing the efforts of glider operators. Full article

(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks 2016)

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11 pages, 273 KiB

Open AccessArticle

Energy Efficient Moving Target Tracking in Wireless Sensor Networks

by Yingyou Wen^1,2, Rui Gao^1,2,* and Hong Zhao^1,2

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

² Key Laboratory of Medical Image Computing of Ministry of Education, Northeastern University, Shenyang 110179, China

Sensors 2016, 16(1), 29; https://doi.org/10.3390/s16010029 - 2 Jan 2016

Cited by 17 | Viewed by 6134

Abstract

Moving target tracking in wireless sensor networks is of paramount importance. This paper considers the problem of state estimation for L-sensor linear dynamic systems. Firstly, the paper establishes the fuzzy model for measurement condition estimation. Then, Generalized Kalman Filter design is performed [...] Read more.

Moving target tracking in wireless sensor networks is of paramount importance. This paper considers the problem of state estimation for L-sensor linear dynamic systems. Firstly, the paper establishes the fuzzy model for measurement condition estimation. Then, Generalized Kalman Filter design is performed to incorporate the novel neighborhood function and the target motion information, improving with an increasing number of active sensors. The proposed measurement selection approach has some advantages in time cost. As such, if the desired accuracy has been achieved, the parameter initialization for optimization can be readily resolved, which maximizes the expected lifespan while preserving tracking accuracy. Through theoretical justifications and empirical studies, we demonstrate that the proposed scheme achieves substantially superior performances over conventional methods in terms of moving target tracking under the resource-constrained wireless sensor networks. Full article

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

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18 pages, 1304 KiB

Open AccessArticle

An Analog-Digital Mixed Measurement Method of Inductive Proximity Sensor

by Yi-Xin Guo^*,†

, Zhi-Biao Shao^†

and Ting Li^†

¹ The School of Electronic and Information Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, China

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 30; https://doi.org/10.3390/s16010030 - 30 Dec 2015

Cited by 13 | Viewed by 10722

Abstract

Inductive proximity sensors (IPSs) are widely used in position detection given their unique advantages. To address the problem of temperature drift, this paper presents an analog-digital mixed measurement method based on the two-dimensional look-up table. The inductance and resistance components can be separated [...] Read more.

Inductive proximity sensors (IPSs) are widely used in position detection given their unique advantages. To address the problem of temperature drift, this paper presents an analog-digital mixed measurement method based on the two-dimensional look-up table. The inductance and resistance components can be separated by processing the measurement data, thus reducing temperature drift and generating quantitative outputs. This study establishes and implements a two-dimensional look-up table that reduces the online computational complexity through structural modeling and by conducting an IPS operating principle analysis. This table is effectively compressed by considering the distribution characteristics of the sample data, thus simplifying the processing circuit. Moreover, power consumption is reduced. A real-time, built-in self-test (BIST) function is also designed and achieved by analyzing abnormal sample data. Experiment results show that the proposed method obtains the advantages of both analog and digital measurements, which are stable, reliable, and taken in real time, without the use of floating-point arithmetic and process-control-based components. The quantitative output of displacement measurement accelerates and stabilizes the system control and detection process. The method is particularly suitable for meeting the high-performance requirements of the aviation and aerospace fields. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 1228 KiB

Open AccessArticle

Multi-Stage Feature Selection Based Intelligent Classifier for Classification of Incipient Stage Fire in Building

by Allan Melvin Andrew^*

, Ammar Zakaria, Shaharil Mad Saad and Ali Yeon Md Shakaff

Centre of Excellence for Advanced Sensor Technology (CEASTech), Universiti Malaysia Perlis, Jejawi, Arau, Perlis 02600, Malaysia

Sensors 2016, 16(1), 31; https://doi.org/10.3390/s16010031 - 19 Jan 2016

Cited by 21 | Viewed by 8556

Abstract

In this study, an early fire detection algorithm has been proposed based on low cost array sensing system, utilising off- the shelf gas sensors, dust particles and ambient sensors such as temperature and humidity sensor. The odour or “smellprint” emanated from various fire [...] Read more.

In this study, an early fire detection algorithm has been proposed based on low cost array sensing system, utilising off- the shelf gas sensors, dust particles and ambient sensors such as temperature and humidity sensor. The odour or “smellprint” emanated from various fire sources and building construction materials at early stage are measured. For this purpose, odour profile data from five common fire sources and three common building construction materials were used to develop the classification model. Normalised feature extractions of the smell print data were performed before subjected to prediction classifier. These features represent the odour signals in the time domain. The obtained features undergo the proposed multi-stage feature selection technique and lastly, further reduced by Principal Component Analysis (PCA), a dimension reduction technique. The hybrid PCA-PNN based approach has been applied on different datasets from in-house developed system and the portable electronic nose unit. Experimental classification results show that the dimension reduction process performed by PCA has improved the classification accuracy and provided high reliability, regardless of ambient temperature and humidity variation, baseline sensor drift, the different gas concentration level and exposure towards different heating temperature range. Full article

(This article belongs to the Special Issue Sensors for Fire Detection)

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13 pages, 371 KiB

Open AccessArticle

Secure and Efficient Reactive Video Surveillance for Patient Monitoring

by An Braeken¹

, Pawani Porambage^2,*,†

, Andrei Gurtov^3,4,†

and Mika Ylianttila^2,†

¹ Department of Industrial Sciences and Technology (INDI), Vrije Universiteit Brussel, Brussels 1000, Belgium

² Centre for Wireless Communication (CWC), University of Oulu, Oulu 90014, Finland

³ Helsinki Institute of Information Technology (HIIT), Aalto University, Espoo 00076, Finland

⁴ Department of “Secure Information Technologies” (SIT), ITMO University, Kronverkskiy prospekt 49, St. Petersburg 197101, Russia

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 32; https://doi.org/10.3390/s16010032 - 2 Jan 2016

Cited by 17 | Viewed by 6264

Abstract

Video surveillance is widely deployed for many kinds of monitoring applications in healthcare and assisted living systems. Security and privacy are two promising factors that align the quality and validity of video surveillance systems with the caliber of patient monitoring applications. In this [...] Read more.

Video surveillance is widely deployed for many kinds of monitoring applications in healthcare and assisted living systems. Security and privacy are two promising factors that align the quality and validity of video surveillance systems with the caliber of patient monitoring applications. In this paper, we propose a symmetric key-based security framework for the reactive video surveillance of patients based on the inputs coming from data measured by a wireless body area network attached to the human body. Only authenticated patients are able to activate the video cameras, whereas the patient and authorized people can consult the video data. User and location privacy are at each moment guaranteed for the patient. A tradeoff between security and quality of service is defined in order to ensure that the surveillance system gets activated even in emergency situations. In addition, the solution includes resistance against tampering with the device on the patient’s side. Full article

(This article belongs to the Special Issue Security and Privacy in Sensor Networks)

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12 pages, 1749 KiB

Open AccessArticle

Wireless Sensors Grouping Proofs for Medical Care and Ambient Assisted-Living Deployment

by Denis Trček

Faculty of Computer and Information Science, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia

Sensors 2016, 16(1), 33; https://doi.org/10.3390/s16010033 - 2 Jan 2016

Cited by 6 | Viewed by 5446

Abstract

Internet of Things (IoT) devices are rapidly penetrating e-health and assisted living domains, and an increasing proportion among them goes on the account of computationally-weak devices, where security and privacy provisioning alone are demanding tasks, not to mention grouping proofs. This paper, therefore, [...] Read more.

Internet of Things (IoT) devices are rapidly penetrating e-health and assisted living domains, and an increasing proportion among them goes on the account of computationally-weak devices, where security and privacy provisioning alone are demanding tasks, not to mention grouping proofs. This paper, therefore, gives an extensive analysis of such proofs and states lessons learnt to avoid possible pitfalls in future designs. It sticks with prudent engineering techniques in this field and deploys in a novel way the so called non-deterministic principle to provide not only grouping proofs, but (among other) also privacy. The developed solution is analyzed by means of a tangible metric and it is shown to be lightweight, and formally for security. Full article

(This article belongs to the Special Issue Security and Privacy in Sensor Networks)

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21 pages, 7825 KiB

Open AccessArticle

The Performance Analysis of the Map-Aided Fuzzy Decision Tree Based on the Pedestrian Dead Reckoning Algorithm in an Indoor Environment

by Kai-Wei Chiang^†, Jhen-Kai Liao^†

, Guang-Je Tsai and Hsiu-Wen Chang^*

¹ Department of Geomatics, National Cheng-Kung University, 1 University Road, Tainan 701, Taiwan

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 34; https://doi.org/10.3390/s16010034 - 28 Dec 2015

Cited by 13 | Viewed by 6916

Abstract

Hardware sensors embedded in a smartphone allow the device to become an excellent mobile navigator. A smartphone is ideal for this task because its great international popularity has led to increased phone power and since most of the necessary infrastructure is already in [...] Read more.

Hardware sensors embedded in a smartphone allow the device to become an excellent mobile navigator. A smartphone is ideal for this task because its great international popularity has led to increased phone power and since most of the necessary infrastructure is already in place. However, using a smartphone for indoor pedestrian navigation can be problematic due to the low accuracy of sensors, imprecise predictability of pedestrian motion, and inaccessibility of the Global Navigation Satellite System (GNSS) in some indoor environments. Pedestrian Dead Reckoning (PDR) is one of the most common technologies used for pedestrian navigation, but in its present form, various errors tend to accumulate. This study introduces a fuzzy decision tree (FDT) aided by map information to improve the accuracy and stability of PDR with less dependency on infrastructure. First, the map is quickly surveyed by the Indoor Mobile Mapping System (IMMS). Next, Bluetooth beacons are implemented to enable the initializing of any position. Finally, map-aided FDT can estimate navigation solutions in real time. The experiments were conducted in different fields using a variety of smartphones and users in order to verify stability. The contrast PDR system demonstrates low stability for each case without pre-calibration and post-processing, but the proposed low-complexity FDT algorithm shows good stability and accuracy under the same conditions. Full article

(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)

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10 pages, 1365 KiB

Open AccessArticle

Effects of Operating Parameters on Measurements of Biochemical Oxygen Demand Using a Mediatorless Microbial Fuel Cell Biosensor

by Min-Chi Hsieh¹, Chiu-Yu Cheng^1,*, Man-Hai Liu² and Ying-Chien Chung^1,*

¹ Department of Biological Science and Technology, China University of Science and Technology, Taipei 11581, Taiwan

² Department of Food Science, China University of Science and Technology, Taipei 11581, Taiwan

Sensors 2016, 16(1), 35; https://doi.org/10.3390/s16010035 - 28 Dec 2015

Cited by 36 | Viewed by 7375

Abstract

The conventional Biochemical Oxygen Demand (BOD) method takes five days to analyze samples. A microbial fuel cell (MFC) may be an alternate tool for rapid BOD determination in water. However, a MFC biosensor for continuous BOD measurements of water samples is still unavailable. [...] Read more.

The conventional Biochemical Oxygen Demand (BOD) method takes five days to analyze samples. A microbial fuel cell (MFC) may be an alternate tool for rapid BOD determination in water. However, a MFC biosensor for continuous BOD measurements of water samples is still unavailable. In this study, a MFC biosensor inoculated with known mixed cultures was used to determine the BOD concentration. Effects of important parameters on establishing a calibration curve between the BOD concentration and output signal from the MFC were evaluated. The results indicate monosaccharides were good fuel, and methionine, phenylalanine, and ethanol were poor fuels for electricity generation by the MFC. Ions in the influent did not significantly affect the MFC performance. CN⁻ in the influent could alleviate the effect of antagonistic electron acceptors on the MFC performance. The regression equation for BOD concentration and current density of the biosensor was y = 0.0145x + 0.3317. It was adopted to measure accurately and continuously the BOD concentration in actual water samples at an acceptable error margin. These results clearly show the developed MFC biosensor has great potential as an alternative BOD sensing device for online measurements of wastewater BOD. Full article

(This article belongs to the Special Issue Microbial and Enzymatic Biosensors)

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19 pages, 3299 KiB

Open AccessArticle

Real-Time Hand Posture Recognition for Human-Robot Interaction Tasks

by Uriel Haile Hernandez-Belmonte

and Victor Ayala-Ramirez^*

Universidad de Guanajuato DICIS, Carr. Salamanca-Valle Km. 3.5 + 1.8, Palo Blanco, Salamanca, C.P. 36885, Mexico

Sensors 2016, 16(1), 36; https://doi.org/10.3390/s16010036 - 4 Jan 2016

Cited by 17 | Viewed by 5997

Abstract

In this work, we present a multiclass hand posture classifier useful for human-robot interaction tasks. The proposed system is based exclusively on visual sensors, and it achieves a real-time performance, whilst detecting and recognizing an alphabet of four hand postures. The proposed approach [...] Read more.

In this work, we present a multiclass hand posture classifier useful for human-robot interaction tasks. The proposed system is based exclusively on visual sensors, and it achieves a real-time performance, whilst detecting and recognizing an alphabet of four hand postures. The proposed approach is based on the real-time deformable detector, a boosting trained classifier. We describe a methodology to design the ensemble of real-time deformable detectors (one for each hand posture that can be classified). Given the lack of standard procedures for performance evaluation, we also propose the use of full image evaluation for this purpose. Such an evaluation methodology provides us with a more realistic estimation of the performance of the method. We have measured the performance of the proposed system and compared it to the one obtained by using only the sampled window approach. We present detailed results of such tests using a benchmark dataset. Our results show that the system can operate in real time at about a 10-fps frame rate. Full article

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

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23 pages, 3176 KiB

Open AccessArticle

Design and Development of Layered Security: Future Enhancements and Directions in Transmission

by Aamir Shahzad¹, Malrey Lee^1,*, Suntae Kim², Kangmin Kim^3,*, Jae-Young Choi^4,*, Younghwa Cho⁴ and Keun-Kwang Lee⁵

¹ Center for Advanced Image and Information Technology, School of Electronics & Information Engineering, Chon Buk National University, 664-14, 1Ga, Deokjin-Dong, Jeonju, Chonbuk 561-756, Korea

² Department of Software Engineering, Chon Buk National University, 664-14, 1Ga, Deokjin-Dong, Jeonju, Chonbuk 561-756, Korea

³ Division of Biotechnology, College of Environmental & Bioresource Sciences, Chonbuk National University, Iksan 570-752, Korea

⁴ College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746, Korea

⁵ Department of Beauty Arts Care, Koguryeo College, Naju 520-930, Korea

Sensors 2016, 16(1), 37; https://doi.org/10.3390/s16010037 - 6 Jan 2016

Cited by 5 | Viewed by 5887

Abstract

Today, security is a prominent issue when any type of communication is being undertaken. Like traditional networks, supervisory control and data acquisition (SCADA) systems suffer from a number of vulnerabilities. Numerous end-to-end security mechanisms have been proposed for the resolution of SCADA-system security [...] Read more.

Today, security is a prominent issue when any type of communication is being undertaken. Like traditional networks, supervisory control and data acquisition (SCADA) systems suffer from a number of vulnerabilities. Numerous end-to-end security mechanisms have been proposed for the resolution of SCADA-system security issues, but due to insecure real-time protocol use and the reliance upon open protocols during Internet-based communication, these SCADA systems can still be compromised by security challenges. This study reviews the security challenges and issues that are commonly raised during SCADA/protocol transmissions and proposes a secure distributed-network protocol version 3 (DNP3) design, and the implementation of the security solution using a cryptography mechanism. Due to the insecurities found within SCADA protocols, the new development consists of a DNP3 protocol that has been designed as a part of the SCADA system, and the cryptographically derived security is deployed within the application layer as a part of the DNP3 stack. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 3872 KiB

Open AccessArticle

Tilted Orientation of Photochromic Dyes with Guest-Host Effect of Liquid Crystalline Polymer Matrix for Electrical UV Sensing

by Amid Ranjkesh¹, Min-Kyu Park¹, Do Hyuk Park², Ji-Sub Park¹, Jun-Chan Choi¹, Sung-Hoon Kim³ and Hak-Rin Kim^1,2,*

¹ School of Electronics Engineering, Kyungpook National University, Daegu 702-701, Korea

² Department of Sensor and Display Engineering, Kyungpook National University, Daegu 702-701, Korea

³ Department of Textile System Engineering, Kyungpook National University, Daegu 702-701, Korea

Sensors 2016, 16(1), 38; https://doi.org/10.3390/s16010038 - 29 Dec 2015

Cited by 10 | Viewed by 7886

Abstract

We propose a highly oriented photochromic dye film for an ultraviolet (UV)-sensing layer, where spirooxazine (SO) derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM) using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results [...] Read more.

We propose a highly oriented photochromic dye film for an ultraviolet (UV)-sensing layer, where spirooxazine (SO) derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM) using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results show that the UV-induced switchable dipole moment amount of the SO derivatives is high; however, their tilting orientation should be controlled. Compared to the dielectric layer with the nearly planar SO dye orientation, the photochromic dielectric layer with the moderately tilted dye orientation shows more than seven times higher the UV-induced capacitance variation. Full article

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

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11 pages, 2592 KiB

Open AccessArticle

Nano-Anatase TiO₂ for High Performance Optical Humidity Sensing on Chip

by Mahdiar Ghadiry^1,*, Mehrdad Gholami², Lai Choon Kong¹, Chong Wu Yi¹, Harith Ahmad¹ and Yatima Alias²

¹ Photonics Research Center, University of Malaya, Kuala Lumpur 50603, Malaysia

² Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia

Sensors 2016, 16(1), 39; https://doi.org/10.3390/s16010039 - 29 Dec 2015

Cited by 28 | Viewed by 6657

Abstract

An on-chip optical humidity sensor using Nano-anatase TiO₂ coating is presented here. The coating material was prepared so that the result is in solution form, making the fabrication process quick and simple. Then, the solution was effortlessly spin-coated on an SU8 straight [...] Read more.

An on-chip optical humidity sensor using Nano-anatase TiO₂ coating is presented here. The coating material was prepared so that the result is in solution form, making the fabrication process quick and simple. Then, the solution was effortlessly spin-coated on an SU8 straight channel waveguide. Investigating the sensitivity and performance (response time) of the device revealed a great linearity in the wide range (35% to 98%) of relative humidity (RH). In addition, a variation of more than 14 dB in transmitted optical power was observed, with a response time of only ~0.7 s. The effect of coating concentration and UV treatment was examined on the performance and repeatability of the sensor. Interesting observations were found, and the attributed mechanisms were described. In addition, the proposed sensor was extensively compared with other state-of-the-art proposed counterparts from the literature and remarkable advantages were found. Since a high sensitivity of ~0.21 dB/%RH and high dynamic performances were demonstrated, this sensor is proposed for use in biomedical applications. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 9037 KiB

Open AccessArticle

Study and Experiment on Non-Contact Voltage Sensor Suitable for Three-Phase Transmission Line

by Qiang Zhou^1,*, Wei He¹, Dongping Xiao¹, Songnong Li² and Kongjun Zhou²

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

² State Grid Chongqing Electric Power CO. Electric Power Research Institute, Chongqing 400015, China

Sensors 2016, 16(1), 40; https://doi.org/10.3390/s16010040 - 30 Dec 2015

Cited by 25 | Viewed by 9181

Abstract

A voltage transformer, as voltage signal detection equipment, plays an important role in a power system. Presently, more and more electric power systems are adopting potential transformer and capacitance voltage transformers. Transformers are often large in volume and heavyweight, their insulation design is [...] Read more.

A voltage transformer, as voltage signal detection equipment, plays an important role in a power system. Presently, more and more electric power systems are adopting potential transformer and capacitance voltage transformers. Transformers are often large in volume and heavyweight, their insulation design is difficult, and an iron core or multi-grade capacitance voltage division structure is generally adopted. As a result, the detection accuracy of transformer is reduced, a huge phase difference exists between detection signal and voltage signal to be measured, and the detection signal cannot accurately and timely reflect the change of conductor voltage signal to be measured. By aiming at the current problems of electric transformation, based on electrostatic induction principle, this paper designed a non-contact voltage sensor and gained detection signal of the sensor through electrostatic coupling for the electric field generated by electric charges of the conductor to be measured. The insulation structure design of the sensor is simple and its volume is small; phase difference of sensor measurement is effectively reduced through optimization design of the electrode; and voltage division ratio and measurement accuracy are increased. The voltage sensor was tested on the experimental platform of simulating three-phase transmission line. According to the result, the designed non-contact voltage sensor can realize accurate and real-time measurement for the conductor voltage. It can be applied to online monitoring for the voltage of three-phase transmission line or three-phase distribution network line, which is in accordance with the development direction of the smart grid. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 12517 KiB

Open AccessArticle

Integrating Sensors into a Marine Drone for Bathymetric 3D Surveys in Shallow Waters

by Francesco Giordano, Gaia Mattei^*

, Claudio Parente, Francesco Peluso and Raffaele Santamaria

Dipartimento di Scienze e Tecnologie, Università degli Studi di Napoli "Parthenope", Centro Direzionale, Isola C4, 80143 Napoli, Italy

Sensors 2016, 16(1), 41; https://doi.org/10.3390/s16010041 - 29 Dec 2015

Cited by 87 | Viewed by 14586

Abstract

This paper demonstrates that accurate data concerning bathymetry as well as environmental conditions in shallow waters can be acquired using sensors that are integrated into the same marine vehicle. An open prototype of an unmanned surface vessel (USV) named MicroVeGA is described. The [...] Read more.

This paper demonstrates that accurate data concerning bathymetry as well as environmental conditions in shallow waters can be acquired using sensors that are integrated into the same marine vehicle. An open prototype of an unmanned surface vessel (USV) named MicroVeGA is described. The focus is on the main instruments installed on-board: a differential Global Position System (GPS) system and single beam echo sounder; inertial platform for attitude control; ultrasound obstacle-detection system with temperature control system; emerged and submerged video acquisition system. The results of two cases study are presented, both concerning areas (Sorrento Marina Grande and Marechiaro Harbour, both in the Gulf of Naples) characterized by a coastal physiography that impedes the execution of a bathymetric survey with traditional boats. In addition, those areas are critical because of the presence of submerged archaeological remains that produce rapid changes in depth values. The experiments confirm that the integration of the sensors improves the instruments’ performance and survey accuracy. Full article

(This article belongs to the Special Issue Sensors and Techniques for 3D Object Modeling in Underwater Environments)

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22 pages, 5307 KiB

Open AccessArticle

AUV Underwater Positioning Algorithm Based on Interactive Assistance of SINS and LBL

by Tao Zhang^1,2,*

, Liping Chen^1,2 and Yao Li^1,2

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

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

Sensors 2016, 16(1), 42; https://doi.org/10.3390/s16010042 - 30 Dec 2015

Cited by 46 | Viewed by 9339

Abstract

This paper studies an underwater positioning algorithm based on the interactive assistance of a strapdown inertial navigation system (SINS) and LBL, and this algorithm mainly includes an optimal correlation algorithm with aided tracking of an SINS/Doppler velocity log (DVL)/magnetic compass pilot (MCP), a [...] Read more.

This paper studies an underwater positioning algorithm based on the interactive assistance of a strapdown inertial navigation system (SINS) and LBL, and this algorithm mainly includes an optimal correlation algorithm with aided tracking of an SINS/Doppler velocity log (DVL)/magnetic compass pilot (MCP), a three-dimensional TDOA positioning algorithm of Taylor series expansion and a multi-sensor information fusion algorithm. The final simulation results show that compared to traditional underwater positioning algorithms, this scheme can not only directly correct accumulative errors caused by a dead reckoning algorithm, but also solves the problem of ambiguous correlation peaks caused by multipath transmission of underwater acoustic signals. The proposed method can calibrate the accumulative error of the AUV position more directly and effectively, which prolongs the underwater operating duration of the AUV. Full article

(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks 2016)

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21 pages, 4093 KiB

Open AccessArticle

Spatio-Temporal Constrained Human Trajectory Generation from the PIR Motion Detector Sensor Network Data: A Geometric Algebra Approach

by Zhaoyuan Yu^1,2,3

, Linwang Yuan^1,2,3, Wen Luo^1,2,*, Linyao Feng¹ and Guonian Lv^1,2,3

¹ Key Laboratory of VGE (Ministry of Education), Nanjing Normal University, No.1 Wenyuan Road, Nanjing 210023, China

² State Key Laboratory Cultivation Base of Geographical Environment Evolution (Jiangsu Province), No.1 Wenyuan Road, Nanjing 210023, China

³ Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, No.1 Wenyuan Road, Nanjing 210023, China

Sensors 2016, 16(1), 43; https://doi.org/10.3390/s16010043 - 30 Dec 2015

Cited by 17 | Viewed by 6930

Abstract

Passive infrared (PIR) motion detectors, which can support long-term continuous observation, are widely used for human motion analysis. Extracting all possible trajectories from the PIR sensor networks is important. Because the PIR sensor does not log location and individual information, none of the [...] Read more.

Passive infrared (PIR) motion detectors, which can support long-term continuous observation, are widely used for human motion analysis. Extracting all possible trajectories from the PIR sensor networks is important. Because the PIR sensor does not log location and individual information, none of the existing methods can generate all possible human motion trajectories that satisfy various spatio-temporal constraints from the sensor activation log data. In this paper, a geometric algebra (GA)-based approach is developed to generate all possible human trajectories from the PIR sensor network data. Firstly, the representation of the geographical network, sensor activation response sequences and the human motion are represented as algebraic elements using GA. The human motion status of each sensor activation are labeled using the GA-based trajectory tracking. Then, a matrix multiplication approach is developed to dynamically generate the human trajectories according to the sensor activation log and the spatio-temporal constraints. The method is tested with the MERL motion database. Experiments show that our method can flexibly extract the major statistical pattern of the human motion. Compared with direct statistical analysis and tracklet graph method, our method can effectively extract all possible trajectories of the human motion, which makes it more accurate. Our method is also likely to provides a new way to filter other passive sensor log data in sensor networks. Full article

(This article belongs to the Section Sensor Networks)

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9 pages, 4077 KiB

Open AccessArticle

Characterization of N-Acylhomoserine Lactones Produced by Bacteria Isolated from Industrial Cooling Water Systems

by Noriya Okutsu¹, Tomohiro Morohoshi^1,*

, Xiaonan Xie², Norihiro Kato¹ and Tsukasa Ikeda¹

¹ Department of Material and Environmental Chemistry, Graduate School of Engineering, Utsunomiya University, 7-1-2 Yoto, Utsunomiya, Tochigi 321-8585, Japan

² Center for Bioscience Research and Education, Utsunomiya University, 350 Mine-machi, Utsunomiya, Tochigi 321-8505, Japan

Sensors 2016, 16(1), 44; https://doi.org/10.3390/s16010044 - 30 Dec 2015

Cited by 15 | Viewed by 7095

Abstract

The cooling water systems are used to remove heat generated in the various industries. Biofouling of the cooling water systems causes blocking of condenser pipes and the heat exchanger tubes. In many Gram-negative bacteria, N-acylhomoserine lactone (AHL) are used as quorum-sensing signal [...] Read more.

The cooling water systems are used to remove heat generated in the various industries. Biofouling of the cooling water systems causes blocking of condenser pipes and the heat exchanger tubes. In many Gram-negative bacteria, N-acylhomoserine lactone (AHL) are used as quorum-sensing signal molecule and associated with biofilm formation. To investigate the relationship between quorum sensing and biofouling in the cooling water system, we isolated a total of 192 bacterial strains from the five cooling water systems, and screened for AHL production. Seven isolates stimulated AHL-mediated purple pigment production in AHL reporter strain Chromobacterium violaceum CV026 or VIR07. Based on their 16S rRNA gene sequences, AHL-producing isolates were assigned to Aeromonas hydrophila, Lysobacter sp., Methylobacterium oryzae, and Bosea massiliensis. To the best of our knowledge, B. massiliensis and Lysobacter sp. have not been reported as AHL-producing species in the previous researches. AHLs extracted from the culture supernatants of B. massiliensis and Lysobacter sp. were identified by liquid chromatography-mass spectrometry. AHLs produced by B. massiliensis were assigned as N-hexanoyl-l-homoserine lactone (C6-HSL), N-(3-oxohexanoyl)-l-homoserine lactone (3-oxo-C6-HSL), and N-(3-oxooctanoyl)-l-homoserine lactone (3-oxo-C8-HSL). AHLs produced by Lysobacter sp. were assigned as N-decanoyl-l-homoserine lactone (C10-HSL) and N-(3-oxodecanoyl)-l-homoserine lactone (3-oxo-C10-HSL). This is the first report of identification of AHLs produced by B. massiliensis and Lysobacter sp. isolated from the cooling water system. Full article

(This article belongs to the Section Biosensors)

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13 pages, 2983 KiB

Open AccessArticle

An Electrically Tunable Zoom System Using Liquid Lenses

by Heng Li^1,†

, Xuemin Cheng^2,† and Qun Hao^1,*

¹ School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China

² Graduate School at Shenzhen, Department of Precision Instrument, Tsinghua University, Shenzhen 518055, China

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 45; https://doi.org/10.3390/s16010045 - 31 Dec 2015

Cited by 23 | Viewed by 7436

Abstract

A four-group stabilized zoom system using two liquid lenses and two fixed lens groups is proposed. We describe the design principle, realization, and the testing of a 5.06:1 zoom system. The realized effective focal length (EFL) range is 6.93 mm to 35.06 mm, [...] Read more.

A four-group stabilized zoom system using two liquid lenses and two fixed lens groups is proposed. We describe the design principle, realization, and the testing of a 5.06:1 zoom system. The realized effective focal length (EFL) range is 6.93 mm to 35.06 mm, and the field of view (FOV) range is 8° to 40°. The system can zoom fast when liquid lens 1’s (L₁’s) optical power take the value from 0.0087 mm⁻¹ to 0.0192 mm⁻¹ and liquid lens 2’s (L₂’s) optical power take the value from 0.0185 mm⁻¹ to −0.01 mm⁻¹. Response time of the realized zoom system was less than 2.5 ms, and the settling time was less than 15 ms.The analysis of elements’ parameters and the measurement of lens performance not only verify the design principle further, but also show the zooming process by the use of two liquid lenses. The system is useful for motion carriers e.g., robot, ground vehicle, and unmanned aerial vehicles considering that it is fast, reliable, and miniature. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 2611 KiB

Open AccessArticle

Low-Power Photoplethysmogram Acquisition Integrated Circuit with Robust Light Interference Compensation

by Jongpal Kim¹, Jihoon Kim²

and Hyoungho Ko^2,*

¹ Samsung Electronics Inc., Suwon 16678, Korea

² Chungnam National University, Daejeon 34134, Korea

Sensors 2016, 16(1), 46; https://doi.org/10.3390/s16010046 - 31 Dec 2015

Cited by 29 | Viewed by 12129

Abstract

To overcome light interference, including a large DC offset and ambient light variation, a robust photoplethysmogram (PPG) readout chip is fabricated using a 0.13-μm complementary metal–oxide–semiconductor (CMOS) process. Against the large DC offset, a saturation detection and current feedback circuit is proposed to [...] Read more.

To overcome light interference, including a large DC offset and ambient light variation, a robust photoplethysmogram (PPG) readout chip is fabricated using a 0.13-μm complementary metal–oxide–semiconductor (CMOS) process. Against the large DC offset, a saturation detection and current feedback circuit is proposed to compensate for an offset current of up to 30 μA. For robustness against optical path variation, an automatic emitted light compensation method is adopted. To prevent ambient light interference, an alternating sampling and charge redistribution technique is also proposed. In the proposed technique, no additional power is consumed, and only three differential switches and one capacitor are required. The PPG readout channel consumes 26.4 μW and has an input referred current noise of 260 pArms. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 1565 KiB

Open AccessArticle

Automated Detection of Firearms and Knives in a CCTV Image

by Michał Grega^*, Andrzej Matiolański

, Piotr Guzik and Mikołaj Leszczuk

AGH University of Science and Technology, al. Mickiewicza 30, Krakow 30-059, Poland

Sensors 2016, 16(1), 47; https://doi.org/10.3390/s16010047 - 1 Jan 2016

Cited by 144 | Viewed by 20831

Abstract

Closed circuit television systems (CCTV) are becoming more and more popular and are being deployed in many offices, housing estates and in most public spaces. Monitoring systems have been implemented in many European and American cities. This makes for an enormous load for [...] Read more.

Closed circuit television systems (CCTV) are becoming more and more popular and are being deployed in many offices, housing estates and in most public spaces. Monitoring systems have been implemented in many European and American cities. This makes for an enormous load for the CCTV operators, as the number of camera views a single operator can monitor is limited by human factors. In this paper, we focus on the task of automated detection and recognition of dangerous situations for CCTV systems. We propose algorithms that are able to alert the human operator when a firearm or knife is visible in the image. We have focused on limiting the number of false alarms in order to allow for a real-life application of the system. The specificity and sensitivity of the knife detection are significantly better than others published recently. We have also managed to propose a version of a firearm detection algorithm that offers a near-zero rate of false alarms. We have shown that it is possible to create a system that is capable of an early warning in a dangerous situation, which may lead to faster and more effective response times and a reduction in the number of potential victims. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 6123 KiB

Open AccessArticle

Geometric and Optic Characterization of a Hemispherical Dome Port for Underwater Photogrammetry

by Fabio Menna^1,*, Erica Nocerino¹, Francesco Fassi²

and Fabio Remondino¹

¹ 3D Optical Metrology unit, Bruno Kessler Foundation (FBK), via Sommarive 18, Trento 38123, Italy

² Politecnico di Milano, ABC Dep. 3DSurvey Group, via Ponzio 31, Milano 20133, Italy

Sensors 2016, 16(1), 48; https://doi.org/10.3390/s16010048 - 2 Jan 2016

Cited by 88 | Viewed by 11992

Abstract

The popularity of automatic photogrammetric techniques has promoted many experiments in underwater scenarios leading to quite impressive visual results, even by non-experts. Despite these achievements, a deep understanding of camera and lens behaviors as well as optical phenomena involved in underwater operations is [...] Read more.

The popularity of automatic photogrammetric techniques has promoted many experiments in underwater scenarios leading to quite impressive visual results, even by non-experts. Despite these achievements, a deep understanding of camera and lens behaviors as well as optical phenomena involved in underwater operations is fundamental to better plan field campaigns and anticipate the achievable results. The paper presents a geometric investigation of a consumer grade underwater camera housing, manufactured by NiMAR and equipped with a 7′′ dome port. After a review of flat and dome ports, the work analyzes, using simulations and real experiments, the main optical phenomena involved when operating a camera underwater. Specific aspects which deal with photogrammetric acquisitions are considered with some tests in laboratory and in a swimming pool. Results and considerations are shown and commented. Full article

(This article belongs to the Special Issue Sensors and Techniques for 3D Object Modeling in Underwater Environments)

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10 pages, 927 KiB

Open AccessArticle

Position and Velocity Estimation for Two-Inertia System with Nonlinear Stiffness Based on Acceleration Sensor

by Kyung-Tae Nam^1,2, Seung-Joon Lee², Tae-Yong Kuc¹ and Hyungjong Kim^2,3,*

¹ Department of Electronic Engineering, Sungkyunkwan Univerity, Suwon 440-746, Korea

² Korea Institute of Industrial Technology, Ansan 426-171, Korea

³ ASRI, Department of Electrical and Computer Engineering, Seoul National University, Seoul 151-744, Korea

Sensors 2016, 16(1), 49; https://doi.org/10.3390/s16010049 - 31 Dec 2015

Cited by 4 | Viewed by 5319

Abstract

In this paper, we consider the state estimation problem for flexible joint manipulators that involve nonlinear characteristics in their stiffness. The two key ideas of our design are that (a) an accelerometer is used in order that the estimation error dynamics do not [...] Read more.

In this paper, we consider the state estimation problem for flexible joint manipulators that involve nonlinear characteristics in their stiffness. The two key ideas of our design are that (a) an accelerometer is used in order that the estimation error dynamics do not depend on nonlinearities at the link part of the manipulators and (b) the model of the nonlinear stiffness is indeed a Lipschitz function. Based on the measured acceleration, we propose a nonlinear observer under the Lipschitz condition of the nonlinear stiffness. In addition, in order to effectively compensate for the estimation error, the gain of the proposed observer is chosen from the ARE (algebraic Riccati equations) which depend on the Lipschitz constant. Comparative experimental results verify the effectiveness of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 2471 KiB

Open AccessArticle

A Novel Method for Speech Acquisition and Enhancement by 94 GHz Millimeter-Wave Sensor

by Fuming Chen^1,†

, Sheng Li^2,†, Chuantao Li^1,†, Miao Liu¹, Zhao Li¹, Huijun Xue¹

, Xijing Jing¹ and Jianqi Wang^1,3,*

¹ Department of Biomedical Engineering, Fourth Military Medical University, Xi’an 710032, China

² College of Control Engineering, Xijing University, Xi’an 710123, China

³ Shaanxi University of Technology, Hanzhong 723001, China

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 50; https://doi.org/10.3390/s16010050 - 31 Dec 2015

Cited by 23 | Viewed by 6569

Abstract

In order to improve the speech acquisition ability of a non-contact method, a 94 GHz millimeter wave (MMW) radar sensor was employed to detect speech signals. This novel non-contact speech acquisition method was shown to have high directional sensitivity, and to be immune [...] Read more.

In order to improve the speech acquisition ability of a non-contact method, a 94 GHz millimeter wave (MMW) radar sensor was employed to detect speech signals. This novel non-contact speech acquisition method was shown to have high directional sensitivity, and to be immune to strong acoustical disturbance. However, MMW radar speech is often degraded by combined sources of noise, which mainly include harmonic, electrical circuit and channel noise. In this paper, an algorithm combining empirical mode decomposition (EMD) and mutual information entropy (MIE) was proposed for enhancing the perceptibility and intelligibility of radar speech. Firstly, the radar speech signal was adaptively decomposed into oscillatory components called intrinsic mode functions (IMFs) by EMD. Secondly, MIE was used to determine the number of reconstructive components, and then an adaptive threshold was employed to remove the noise from the radar speech. The experimental results show that human speech can be effectively acquired by a 94 GHz MMW radar sensor when the detection distance is 20 m. Moreover, the noise of the radar speech is greatly suppressed and the speech sounds become more pleasant to human listeners after being enhanced by the proposed algorithm, suggesting that this novel speech acquisition and enhancement method will provide a promising alternative for various applications associated with speech detection. Full article

(This article belongs to the Section Remote Sensors)

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17 pages, 1575 KiB

Open AccessReview

Blood Group Typing: From Classical Strategies to the Application of Synthetic Antibodies Generated by Molecular Imprinting

by Adnan Mujahid^1,2

and Franz L. Dickert^1,*

¹ Department of Analytical Chemistry, University of Vienna, Währinger Straße 38, A-1090 Vienna, Austria

² Institute of Chemistry, University of the Punjab, Quaid-i-Azam Campus Lahore 54590, Pakistan

Sensors 2016, 16(1), 51; https://doi.org/10.3390/s16010051 - 31 Dec 2015

Cited by 68 | Viewed by 22146

Abstract

Blood transfusion requires a mandatory cross-match test to examine the compatibility between donor and recipient blood groups. Generally, in all cross-match tests, a specific chemical reaction of antibodies with erythrocyte antigens is carried out to monitor agglutination. Since the visual inspection is no [...] Read more.

Blood transfusion requires a mandatory cross-match test to examine the compatibility between donor and recipient blood groups. Generally, in all cross-match tests, a specific chemical reaction of antibodies with erythrocyte antigens is carried out to monitor agglutination. Since the visual inspection is no longer useful for obtaining precise quantitative information, therefore there is a wide variety of different technologies reported in the literature to recognize the agglutination reactions. Despite the classical methods, modern biosensors and molecular blood typing strategies have also been considered for straightforward, accurate and precise analysis. The interfacial part of a typical sensor device could range from natural antibodies to synthetic receptor materials, as designed by molecular imprinting and which is suitably integrated with the transducer surface. Herein, we present a comprehensive overview of some selected strategies extending from traditional practices to modern procedures in blood group typing, thus to highlight the most promising approach among emerging technologies. Full article

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

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13 pages, 2703 KiB

Open AccessArticle

A Microwave Ring-Resonator Sensor for Non-Invasive Assessment of Meat Aging

by Muhammad Taha Jilani¹, Wong Peng Wen^1,*, Lee Yen Cheong² and Muhammad Zaka Ur Rehman¹

¹ Department of Electrical and Electronics Engineering, University Technology PETRONAS, Bandar Seri Iskandar 32610, Malaysia

² Department of Fundamental and Applied Science, University Technology PETRONAS, Bandar Seri Iskandar 32610, Malaysia

Sensors 2016, 16(1), 52; https://doi.org/10.3390/s16010052 - 20 Jan 2016

Cited by 40 | Viewed by 9799

Abstract

The assessment of moisture loss from meat during the aging period is a critical issue for the meat industry. In this article, a non-invasive microwave ring-resonator sensor is presented to evaluate the moisture content, or more precisely water holding capacity (WHC) of broiler [...] Read more.

The assessment of moisture loss from meat during the aging period is a critical issue for the meat industry. In this article, a non-invasive microwave ring-resonator sensor is presented to evaluate the moisture content, or more precisely water holding capacity (WHC) of broiler meat over a four-week period. The developed sensor has shown significant changes in its resonance frequency and return loss due to reduction in WHC in the studied duration. The obtained results are also confirmed by physical measurements. Further, these results are evaluated using the Fricke model, which provides a good fit for electric circuit components in biological tissue. Significant changes were observed in membrane integrity, where the corresponding capacitance decreases 30% in the early aging (0D-7D) period. Similarly, the losses associated with intracellular and extracellular fluids exhibit changed up to 42% and 53%, respectively. Ultimately, empirical polynomial models are developed to predict the electrical component values for a better understanding of aging effects. The measured and calculated values are found to be in good agreement. Full article

(This article belongs to the Section Physical Sensors)

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31 pages, 1890 KiB

Open AccessArticle

Energy-Efficient Control with Harvesting Predictions for Solar-Powered Wireless Sensor Networks

by Tengyue Zou^*

, Shouying Lin, Qijie Feng and Yanlian Chen

College of Mechanical and Electronic Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China

Sensors 2016, 16(1), 53; https://doi.org/10.3390/s16010053 - 4 Jan 2016

Cited by 57 | Viewed by 7960

Abstract

Wireless sensor networks equipped with rechargeable batteries are useful for outdoor environmental monitoring. However, the severe energy constraints of the sensor nodes present major challenges for long-term applications. To achieve sustainability, solar cells can be used to acquire energy from the environment. Unfortunately, [...] Read more.

Wireless sensor networks equipped with rechargeable batteries are useful for outdoor environmental monitoring. However, the severe energy constraints of the sensor nodes present major challenges for long-term applications. To achieve sustainability, solar cells can be used to acquire energy from the environment. Unfortunately, the energy supplied by the harvesting system is generally intermittent and considerably influenced by the weather. To improve the energy efficiency and extend the lifetime of the networks, we propose algorithms for harvested energy prediction using environmental shadow detection. Thus, the sensor nodes can adjust their scheduling plans accordingly to best suit their energy production and residual battery levels. Furthermore, we introduce clustering and routing selection methods to optimize the data transmission, and a Bayesian network is used for warning notifications of bottlenecks along the path. The entire system is implemented on a real-time Texas Instruments CC2530 embedded platform, and the experimental results indicate that these mechanisms sustain the networks’ activities in an uninterrupted and efficient manner. Full article

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

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9 pages, 8888 KiB

Open AccessArticle

PIMR: Parallel and Integrated Matching for Raw Data

by Zhenghao Li^1,2,*, Junying Yang¹, Jiaduo Zhao¹, Peng Han² and Zhi Chai³

¹ Key Laboratory for Optoelectronic Technology and Systems of Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China

² Chongqing Academy of Science and Technology, Chongqing 401123, China

³ Beijing Institute of Environmental Features, Beijing 100854, China

Sensors 2016, 16(1), 54; https://doi.org/10.3390/s16010054 - 2 Jan 2016

Cited by 2 | Viewed by 5198

Abstract

With the trend of high-resolution imaging, computational costs of image matching have substantially increased. In order to find the compromise between accuracy and computation in real-time applications, we bring forward a fast and robust matching algorithm, named parallel and integrated matching for raw [...] Read more.

With the trend of high-resolution imaging, computational costs of image matching have substantially increased. In order to find the compromise between accuracy and computation in real-time applications, we bring forward a fast and robust matching algorithm, named parallel and integrated matching for raw data (PIMR). This algorithm not only effectively utilizes the color information of raw data, but also designs a parallel and integrated framework to shorten the time-cost in the demosaicing stage. Experiments show that compared to existing state-of-the-art methods, the proposed algorithm yields a comparable recognition rate, while the total time-cost of imaging and matching is significantly reduced. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 3260 KiB

Open AccessArticle

Bio-Inspired Stretchable Absolute Pressure Sensor Network

by Yue Guo^1,*, Yu-Hung Li², Zhiqiang Guo³, Kyunglok Kim¹, Fu-Kuo Chang⁴ and Shan X. Wang^1,2

¹ Department of Electrical Engineering, Stanford University, 350 Serra Mall, Stanford, CA 94305, USA

² Department of Materials Science and Engineering, Stanford University, 476 Lomita Mall, Stanford, CA 94305, USA

³ Department of Mechanical Engineering, Stanford University, 440 Escondido Mall, Stanford, CA 94305, USA

⁴ Department of Aeronautics and Astronautics, Stanford University, 496 Lomita Mall, Stanford, CA 94305, USA

Sensors 2016, 16(1), 55; https://doi.org/10.3390/s16010055 - 2 Jan 2016

Cited by 26 | Viewed by 10428

Abstract

A bio-inspired absolute pressure sensor network has been developed. Absolute pressure sensors, distributed on multiple silicon islands, are connected as a network by stretchable polyimide wires. This sensor network, made on a 4’’ wafer, has 77 nodes and can be mounted on various [...] Read more.

A bio-inspired absolute pressure sensor network has been developed. Absolute pressure sensors, distributed on multiple silicon islands, are connected as a network by stretchable polyimide wires. This sensor network, made on a 4’’ wafer, has 77 nodes and can be mounted on various curved surfaces to cover an area up to 0.64 m × 0.64 m, which is 100 times larger than its original size. Due to Micro Electro-Mechanical system (MEMS) surface micromachining technology, ultrathin sensing nodes can be realized with thicknesses of less than 100 µm. Additionally, good linearity and high sensitivity (~14 mV/V/bar) have been achieved. Since the MEMS sensor process has also been well integrated with a flexible polymer substrate process, the entire sensor network can be fabricated in a time-efficient and cost-effective manner. Moreover, an accurate pressure contour can be obtained from the sensor network. Therefore, this absolute pressure sensor network holds significant promise for smart vehicle applications, especially for unmanned aerial vehicles. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 1873 KiB

Open AccessArticle

Construction of an Electrochemical Sensor Based on Carbon Nanotubes/Gold Nanoparticles for Trace Determination of Amoxicillin in Bovine Milk

by Aliyu Muhammad¹, Nor Azah Yusof^1,2,*, Reza Hajian^2,* and Jaafar Abdullah^1,2

¹ Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Selangor, Malaysia

² Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Selangor, Malaysia

Sensors 2016, 16(1), 56; https://doi.org/10.3390/s16010056 - 20 Jan 2016

Cited by 67 | Viewed by 9773

Abstract

In this work, a novel electrochemical sensor was fabricated for determination of amoxicillin in bovine milk samples by decoration of carboxylated multi-walled carbon nanotubes (MWCNTs) with gold nanoparticles (AuNPs) using ethylenediamine (en) as a cross linker (AuNPs/en-MWCNTs). The constructed nanocomposite was homogenized in [...] Read more.

In this work, a novel electrochemical sensor was fabricated for determination of amoxicillin in bovine milk samples by decoration of carboxylated multi-walled carbon nanotubes (MWCNTs) with gold nanoparticles (AuNPs) using ethylenediamine (en) as a cross linker (AuNPs/en-MWCNTs). The constructed nanocomposite was homogenized in dimethylformamide and drop casted on screen printed electrode. Field emission scanning electron microscopy (FESEM), energy dispersive X-Ray (EDX), X-Ray diffraction (XRD) and cyclic voltammetry were used to characterize the synthesized nanocomposites. The results show that the synthesized nanocomposites induced a remarkable synergetic effect for the oxidation of amoxicillin. Effect of some parameters, including pH, buffer, scan rate, accumulation potential, accumulation time and amount of casted nanocomposites, on the sensitivity of fabricated sensor were optimized. Under the optimum conditions, there was two linear calibration ranges from 0.2–10 µM and 10–30 µM with equations of I_pa (µA) = 2.88C (µM) + 1.2017; r = 0.9939 and I_pa (µA) = 0.88C (µM) + 22.97; r = 0.9973, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were calculated as 0.015 µM and 0.149 µM, respectively. The fabricated electrochemical sensor was successfully applied for determination of Amoxicillin in bovine milk samples and all results compared with high performance liquid chromatography (HPLC) standard method. Full article

(This article belongs to the Section Chemical Sensors)

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15 pages, 18193 KiB

Open AccessArticle

Self-Powered WSN for Distributed Data Center Monitoring

by Davide Brunelli¹

, Roberto Passerone²

, Luca Rizzon^2,*, Maurizio Rossi¹

and Davide Sartori¹

¹ Department of Industrial Engineering (DII), University of Trento, via Sommarive 9, Povo (TN) I-38123, Italy

² Department of Information Engineering and Computer Science (DISI), University of Trento, via Sommarive 9, Povo (TN) I-38123, Italy

Sensors 2016, 16(1), 57; https://doi.org/10.3390/s16010057 - 2 Jan 2016

Cited by 17 | Viewed by 7959

Abstract

Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental [...] Read more.

Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental parameters in servers and racks. It is powered by an energy harvesting module based on Thermoelectric Generators, which converts the heat dissipation from the servers. Starting from the empirical characterization of the energy harvester, we present a power conditioning circuit optimized for the specific application. The whole system has been enhanced with several sensors. An ultra-low-power micro-controller stacked over the energy harvesting provides an efficient power management. Performance have been assessed and compared with the analytical model for validation. Full article

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

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12 pages, 2924 KiB

Open AccessArticle

Characterizations and Electrical Modelling of Sensory Samples Formed from Synthesized Vanadium (V) Oxide and Copper Oxide Graphene Quantum Tunneling Composites (GQTC) Applied in Electrotribology

by Tadeusz Habdank-Wojewódzki^1,†, Josef Habdank^2,*,†, Przemyslaw Cwik^3,† and Slawomir Zimowski⁴

¹ AGH University of Science and Technology, Department of Electronics, Mickiewicza 30, 30-059 Krakow, Poland

² Graphenalloy, Ordrupvej 69, 3th, 2920 Charlottenlund, Denmark

³ Delphi Automotive Systems, Powstancow Wielkopolskich 13 D-E, 30-962 Krakow, Poland

⁴ AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Mickiewicza 30, 30-059 Krakow, Poland

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 58; https://doi.org/10.3390/s16010058 - 5 Jan 2016

Viewed by 5271

Abstract

CuO and V₂O₅ graphene quantum tunneling composites (GQTC) presented in this article were produced and their sensory properties were analyzed. The composites were synthesised using two stage high-power milling process, which resulted in materials that have good temeprature and pressure [...] Read more.

CuO and V₂O₅ graphene quantum tunneling composites (GQTC) presented in this article were produced and their sensory properties were analyzed. The composites were synthesised using two stage high-power milling process, which resulted in materials that have good temeprature and pressure sensory properties. Described production process defines internal structure of materials such that when used as sensor in the desired range, it exhibits a strong percolation effect. The experiment, with controlled changing physical conditions during electrotribological measurement, enabled analyzing of the composites’ conductivity as a function of the sensory properties: applied temperature, pressure, tangential force and wear. The sensory characteristic was successfully modelled by invertible generalized equations, and used to create sensor capable of estimating temperature or pressure in the real time. The developed materials have the potential to be applied in the areas where miniaturization is essential, due to the materials exhibiting good sensory properties in mini and micro scale. Full article

(This article belongs to the Special Issue Advanced Sensors and Sensing Materials-Seleted Papers from Advanced Materials World Congress, 23-26 August Stockholm, Sweden)

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17 pages, 476 KiB

Open AccessArticle

A Deadline-Aware Scheduling and Forwarding Scheme in Wireless Sensor Networks

by Thi-Nga Dao¹, Seokhoon Yoon^1,* and Jangyoung Kim²

¹ Department of Electrical and Computer Engineering, University of Ulsan, Ulsan 680-749, Korea

² Department of Computer Science, University of Suwon, Gyeonggi 445-743, Korea

Sensors 2016, 16(1), 59; https://doi.org/10.3390/s16010059 - 5 Jan 2016

Cited by 15 | Viewed by 5208

Abstract

Many applications in wireless sensor networks (WSNs) require energy consumption to be minimized and the data delivered to the sink within a specific delay. A usual solution for reducing energy consumption is duty cycling, in which nodes periodically switch between sleep and active [...] Read more.

Many applications in wireless sensor networks (WSNs) require energy consumption to be minimized and the data delivered to the sink within a specific delay. A usual solution for reducing energy consumption is duty cycling, in which nodes periodically switch between sleep and active states. By increasing the duty cycle interval, consumed energy can be reduced more. However, a large duty cycle interval causes a long end-to-end (E2E) packet delay. As a result, the requirement of a specific delay bound for packet delivery may not be satisfied. In this paper, we aim at maximizing the duty cycle while still guaranteeing that the packets arrive at the sink with the required probability, i.e., the required delay-constrained success ratio (DCSR) is achieved. In order to meet this objective, we propose a novel scheduling and forwarding scheme, namely the deadline-aware scheduling and forwarding (DASF) algorithm. In DASF, the E2E delay distribution with the given network model and parameters is estimated in order to determine the maximum duty cycle interval, with which the required DCSR is satisfied. Each node independently selects a wake-up time using the selected interval, and packets are forwarded to a node in the potential forwarding set, which is determined based on the distance between nodes and the sink. DASF does not require time synchronization between nodes, and a node does not need to maintain neighboring node information in advance. Simulation results show that the proposed scheme can satisfy a required delay-constrained success ratio and outperforms existing algorithms in terms of E2E delay and DCSR. Full article

(This article belongs to the Section Sensor Networks)

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22 pages, 4026 KiB

Open AccessArticle

Estimation of Gaze Detection Accuracy Using the Calibration Information-Based Fuzzy System

by Su Yeong Gwon, Dongwook Jung, Weiyuan Pan and Kang Ryoung Park^*

Division of Electronics and Electrical Engineering, Dongguk University, 30, Pildong-ro 1-gil, Jung-gu, Seoul 100-715, Korea

Sensors 2016, 16(1), 60; https://doi.org/10.3390/s16010060 - 5 Jan 2016

Cited by 3 | Viewed by 6549

Abstract

Gaze tracking is a camera-vision based technology for identifying the location where a user is looking. In general, a calibration process is applied at the initial stage of most gaze tracking systems. This process is necessary to calibrate for the differences in the [...] Read more.

Gaze tracking is a camera-vision based technology for identifying the location where a user is looking. In general, a calibration process is applied at the initial stage of most gaze tracking systems. This process is necessary to calibrate for the differences in the eyeballs and cornea size of the user, as well as the angle kappa, and to find the relationship between the user’s eye and screen coordinates. It is applied on the basis of the information of the user’s pupil and corneal specular reflection obtained while the user is looking at several predetermined positions on a screen. In previous studies, user calibration was performed using various types of markers and marker display methods. However, studies on estimating the accuracy of gaze detection through the results obtained during the calibration process have yet to be carried out. Therefore, we propose the method for estimating the accuracy of a final gaze tracking system with a near-infrared (NIR) camera by using a fuzzy system based on the user calibration information. Here, the accuracy of the final gaze tracking system ensures the gaze detection accuracy during the testing stage of the gaze tracking system. Experiments were performed using a total of four types of markers and three types of marker display methods. From them, it was found that the proposed method correctly estimated the accuracy of the gaze tracking regardless of the various marker and marker display types applied. Full article

(This article belongs to the Section Physical Sensors)

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7 pages, 1969 KiB

Open AccessArticle

Detection of Organic Compounds in Water by an Optical Absorbance Method

by Chihoon Kim^1,2, Joo Beom Eom², Soyoun Jung³ and Taeksoo Ji^1,*

¹ School of Electronics and Computer Engineering, Chonnam National University, 300 Youngbong-dong, Buk-gu, Gwangju 500-757, Korea

² Korea Photonics Technology Institute, Medical Photonics Research Center, 9, Cheomdan venture-ro 108beon-gil, Buk-gu, Gwangju 500-779, Korea

³ Samsung Display Co. Ltd., Samsung st. 181, Tangjeong-Myeon, Asan 335-741, Korea

Sensors 2016, 16(1), 61; https://doi.org/10.3390/s16010061 - 4 Jan 2016

Cited by 41 | Viewed by 10050

Abstract

This paper proposes an optical method which allows determination of the organic compound concentration in water by measurement of the UV (ultraviolet) absorption at a wavelength of 250 nm~300 nm. The UV absorbance was analyzed by means of a multiple linear regression model [...] Read more.

This paper proposes an optical method which allows determination of the organic compound concentration in water by measurement of the UV (ultraviolet) absorption at a wavelength of 250 nm~300 nm. The UV absorbance was analyzed by means of a multiple linear regression model for estimation of the total organic carbon contents in water, which showed a close correlation with the UV absorbance, demonstrating a high adjusted coefficient of determination, 0.997. The comparison of the TOC (total organic carbon) concentrations for real samples (tab water, sea, and river) calculated from the UV absorbance spectra, and those measured by a conventional TOC analyzer indicates that the higher the TOC value the better the agreement. This UV absorbance method can be easily configured for real-time monitoring water pollution, and built into a compact system applicable to industry areas. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 2809 KiB

Open AccessArticle

Pedestrian Counting with Occlusion Handling Using Stereo Thermal Cameras

by Miklas S. Kristoffersen, Jacob V. Dueholm, Rikke Gade^*

and Thomas B. Moeslund

Visual Analysis of People Lab, Aalborg University, Rendsburggade 14, 9000 Aalborg, Denmark

Sensors 2016, 16(1), 62; https://doi.org/10.3390/s16010062 - 5 Jan 2016

Cited by 51 | Viewed by 11544

Abstract

The number of pedestrians walking the streets or gathered in public spaces is a valuable piece of information for shop owners, city governments, event organizers and many others. However, automatic counting that takes place day and night is challenging due to changing lighting [...] Read more.

The number of pedestrians walking the streets or gathered in public spaces is a valuable piece of information for shop owners, city governments, event organizers and many others. However, automatic counting that takes place day and night is challenging due to changing lighting conditions and the complexity of scenes with many people occluding one another. To address these challenges, this paper introduces the use of a stereo thermal camera setup for pedestrian counting. We investigate the reconstruction of 3D points in a pedestrian street with two thermal cameras and propose an algorithm for pedestrian counting based on clustering and tracking of the 3D point clouds. The method is tested on two five-minute video sequences captured at a public event with a moderate density of pedestrians and heavy occlusions. The counting performance is compared to the manually annotated ground truth and shows success rates of 95.4% and 99.1% for the two sequences. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 13253 KiB

Open AccessArticle

Contactless Inductive Bubble Detection in a Liquid Metal Flow

by Thomas Gundrum^1,*

, Philipp Büttner¹, Bachir Dekdouk², Anthony Peyton²

, Thomas Wondrak¹, Vladimir Galindo¹ and Sven Eckert¹

¹ Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, Dresden 01328, Germany

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

Sensors 2016, 16(1), 63; https://doi.org/10.3390/s16010063 - 6 Jan 2016

Cited by 16 | Viewed by 8799

Abstract

The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods [...] Read more.

The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods based on electromagnetic induction. We will present a measurement system which consists of one excitation coil and a pickup coil system on the opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe and bubbles in a column filled with a liquid Gallium alloy. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 1233 KiB

Open AccessArticle

Performance Evaluation of Target Detection with a Near-Space Vehicle-Borne Radar in Blackout Condition

by Yanpeng Li^*

, Xiang Li, Hongqiang Wang, Bin Deng and Yuliang Qin

School of Electrical Science and Engineering, National University of Defense Technology, 137 Yanwachi Street, Changsha 410073, China

Sensors 2016, 16(1), 64; https://doi.org/10.3390/s16010064 - 6 Jan 2016

Cited by 11 | Viewed by 4913

Abstract

Radar is a very important sensor in surveillance applications. Near-space vehicle-borne radar (NSVBR) is a novel installation of a radar system, which offers many benefits, like being highly suited to the remote sensing of extremely large areas, having a rapidly deployable capability and [...] Read more.

Radar is a very important sensor in surveillance applications. Near-space vehicle-borne radar (NSVBR) is a novel installation of a radar system, which offers many benefits, like being highly suited to the remote sensing of extremely large areas, having a rapidly deployable capability and having low vulnerability to electronic countermeasures. Unfortunately, a target detection challenge arises because of complicated scenarios, such as nuclear blackout, rain attenuation, etc. In these cases, extra care is needed to evaluate the detection performance in blackout situations, since this a classical problem along with the application of an NSVBR. However, the existing evaluation measures are the probability of detection and the receiver operating curve (ROC), which cannot offer detailed information in such a complicated application. This work focuses on such requirements. We first investigate the effect of blackout on an electromagnetic wave. Performance evaluation indexes are then built: three evaluation indexes on the detection capability and two evaluation indexes on the robustness of the detection process. Simulation results show that the proposed measure will offer information on the detailed performance of detection. These measures are therefore very useful in detecting the target of interest in a remote sensing system and are helpful for both the NSVBR designers and users. Full article

(This article belongs to the Section Remote Sensors)

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19 pages, 2940 KiB

Open AccessArticle

A Comparison of Alternative Distributed Dynamic Cluster Formation Techniques for Industrial Wireless Sensor Networks

by Mohammad Gholami and Robert W. Brennan^*

Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada

Sensors 2016, 16(1), 65; https://doi.org/10.3390/s16010065 - 6 Jan 2016

Cited by 18 | Viewed by 7280

Abstract

In this paper, we investigate alternative distributed clustering techniques for wireless sensor node tracking in an industrial environment. The research builds on extant work on wireless sensor node clustering by reporting on: (1) the development of a novel distributed management approach for tracking [...] Read more.

In this paper, we investigate alternative distributed clustering techniques for wireless sensor node tracking in an industrial environment. The research builds on extant work on wireless sensor node clustering by reporting on: (1) the development of a novel distributed management approach for tracking mobile nodes in an industrial wireless sensor network; and (2) an objective comparison of alternative cluster management approaches for wireless sensor networks. To perform this comparison, we focus on two main clustering approaches proposed in the literature: pre-defined clusters and ad hoc clusters. These approaches are compared in the context of their reconfigurability: more specifically, we investigate the trade-off between the cost and the effectiveness of competing strategies aimed at adapting to changes in the sensing environment. To support this work, we introduce three new metrics: a cost/efficiency measure, a performance measure, and a resource consumption measure. The results of our experiments show that ad hoc clusters adapt more readily to changes in the sensing environment, but this higher level of adaptability is at the cost of overall efficiency. Full article

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

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20 pages, 236 KiB

Open AccessReview

Gait Partitioning Methods: A Systematic Review

by Juri Taborri^1,*, Eduardo Palermo¹

, Stefano Rossi²

and Paolo Cappa^1,3

¹ Department of Mechanical and Aerospace Engineering, Sapienza University of Roma, Via Eudossiana 18, Roma I-00184, Italy

² Department of Economics and Management, Industrial Engineering (DEIM), University of Tuscia, Via del Paradiso 47, Viterbo I-01100, Italy

³ MARLab, Movement Analysis and Robotics Laboratory, Neurorehabilitation Division, IRCCS Children’s Hospital “Bambino Gesù”, Via Torre di Palidoro snc, Fiumicino (RM) I-00050, Italy

Sensors 2016, 16(1), 66; https://doi.org/10.3390/s16010066 - 6 Jan 2016

Cited by 294 | Viewed by 16273

Abstract

In the last years, gait phase partitioning has come to be a challenging research topic due to its impact on several applications related to gait technologies. A variety of sensors can be used to feed algorithms for gait phase partitioning, mainly classifiable as [...] Read more.

In the last years, gait phase partitioning has come to be a challenging research topic due to its impact on several applications related to gait technologies. A variety of sensors can be used to feed algorithms for gait phase partitioning, mainly classifiable as wearable or non-wearable. Among wearable sensors, footswitches or foot pressure insoles are generally considered as the gold standard; however, to overcome some inherent limitations of the former, inertial measurement units have become popular in recent decades. Valuable results have been achieved also though electromyography, electroneurography, and ultrasonic sensors. Non-wearable sensors, such as opto-electronic systems along with force platforms, remain the most accurate system to perform gait analysis in an indoor environment. In the present paper we identify, select, and categorize the available methodologies for gait phase detection, analyzing advantages and disadvantages of each solution. Finally, we comparatively examine the obtainable gait phase granularities, the usable computational methodologies and the optimal sensor placements on the targeted body segments. Full article

(This article belongs to the Special Issue Wearable Sensors)

8 pages, 1157 KiB

Open AccessArticle

Integrated Amorphous Silicon p-i-n Temperature Sensor for CMOS Photonics

by Sandro Rao^*

, Giovanni Pangallo and Francesco Giuseppe Della Corte

Department of Information Engineering Infrastructures and Sustainable Energy (DIIES), “Mediterranea” University, Reggio Calabria 89122, Italy

Sensors 2016, 16(1), 67; https://doi.org/10.3390/s16010067 - 6 Jan 2016

Cited by 20 | Viewed by 6883

Abstract

Hydrogenated amorphous silicon (a-Si:H) shows interesting optoelectronic and technological properties that make it suitable for the fabrication of passive and active micro-photonic devices, compatible moreover with standard microelectronic devices on a microchip. A temperature sensor based on a hydrogenated amorphous silicon p-i-n diode [...] Read more.

Hydrogenated amorphous silicon (a-Si:H) shows interesting optoelectronic and technological properties that make it suitable for the fabrication of passive and active micro-photonic devices, compatible moreover with standard microelectronic devices on a microchip. A temperature sensor based on a hydrogenated amorphous silicon p-i-n diode integrated in an optical waveguide for silicon photonics applications is presented here. The linear dependence of the voltage drop across the forward-biased diode on temperature, in a range from 30 °C up to 170 °C, has been used for thermal sensing. A high sensitivity of 11.9 mV/°C in the bias current range of 34–40 nA has been measured. The proposed device is particularly suitable for the continuous temperature monitoring of CMOS-compatible photonic integrated circuits, where the behavior of the on-chip active and passive devices are strongly dependent on their operating temperature. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 4155 KiB

Open AccessArticle

A Novel Hybrid Error Criterion-Based Active Control Method for on-Line Milling Vibration Suppression with Piezoelectric Actuators and Sensors

by Xingwu Zhang^1,2, Chenxi Wang¹, Robert X. Gao², Ruqiang Yan^2,3, Xuefeng Chen^1,* and Shibin Wang¹

¹ State Key Laboratory for Manufacturing System Engineering, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China

² Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106, USA

³ School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

Sensors 2016, 16(1), 68; https://doi.org/10.3390/s16010068 - 6 Jan 2016

Cited by 25 | Viewed by 6396

Abstract

Milling vibration is one of the most serious factors affecting machining quality and precision. In this paper a novel hybrid error criterion-based frequency-domain LMS active control method is constructed and used for vibration suppression of milling processes by piezoelectric actuators and sensors, in [...] Read more.

Milling vibration is one of the most serious factors affecting machining quality and precision. In this paper a novel hybrid error criterion-based frequency-domain LMS active control method is constructed and used for vibration suppression of milling processes by piezoelectric actuators and sensors, in which only one Fast Fourier Transform (FFT) is used and no Inverse Fast Fourier Transform (IFFT) is involved. The correction formulas are derived by a steepest descent procedure and the control parameters are analyzed and optimized. Then, a novel hybrid error criterion is constructed to improve the adaptability, reliability and anti-interference ability of the constructed control algorithm. Finally, based on piezoelectric actuators and acceleration sensors, a simulation of a spindle and a milling process experiment are presented to verify the proposed method. Besides, a protection program is added in the control flow to enhance the reliability of the control method in applications. The simulation and experiment results indicate that the proposed method is an effective and reliable way for on-line vibration suppression, and the machining quality can be obviously improved. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 4050 KiB

Open AccessArticle

Lead-Free Piezoelectric Diaphragm Biosensors Based on Micro-Machining Technology and Chemical Solution Deposition

by Xiaomeng Li¹, Xiaoqing Wu^1,*, Peng Shi¹ and Zuo-Guang Ye^1,2

¹ Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049, China

² Department of Chemistry and 4D LABS, Simon Fraser University, Burnaby, BC V5A 1S6, Canada

Sensors 2016, 16(1), 69; https://doi.org/10.3390/s16010069 - 12 Jan 2016

Cited by 6 | Viewed by 5873

Abstract

In this paper, we present a new approach to the fabrication of integrated silicon-based piezoelectric diaphragm-type biosensors by using sodium potassium niobate-silver niobate (0.82KNN-0.18AN) composite lead-free thin film as the piezoelectric layer. The piezoelectric diaphragms were designed and fabricated by micro-machining technology and [...] Read more.

In this paper, we present a new approach to the fabrication of integrated silicon-based piezoelectric diaphragm-type biosensors by using sodium potassium niobate-silver niobate (0.82KNN-0.18AN) composite lead-free thin film as the piezoelectric layer. The piezoelectric diaphragms were designed and fabricated by micro-machining technology and chemical solution deposition. The fabricated device was very sensitive to the mass changes caused by various targets attached on the surface of diaphragm. The measured mass sensitivity value was about 931 Hz/μg. Its good performance shows that the piezoelectric diaphragm biosensor can be used as a cost-effective platform for nucleic acid testing. Full article

(This article belongs to the Section Biosensors)

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17 pages, 6011 KiB

Open AccessArticle

Design and Analysis of a Sensor System for Cutting Force Measurement in Machining Processes

by Qiaokang Liang^1,2,*,†

, Dan Zhang^3,†, Gianmarc Coppola³, Jianxu Mao¹, Wei Sun^1,2,*, Yaonan Wang^1,2,* and Yunjian Ge⁴

¹ College of Electric and Information Technology, Hunan University, Changsha 410082, Hunan, China

² State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, Hunan, China

³ Lassonde School of Engineering, York University, Toronto, ON M3J 1P3, Canada

⁴ Institute of Intelligent Machines, Chinese Academy of Science, Hefei 230031, Anhui, China

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 70; https://doi.org/10.3390/s16010070 - 7 Jan 2016

Cited by 55 | Viewed by 8870

Abstract

Multi-component force sensors have infiltrated a wide variety of automation products since the 1970s. However, one seldom finds full-component sensor systems available in the market for cutting force measurement in machine processes. In this paper, a new six-component sensor system with a compact [...] Read more.

Multi-component force sensors have infiltrated a wide variety of automation products since the 1970s. However, one seldom finds full-component sensor systems available in the market for cutting force measurement in machine processes. In this paper, a new six-component sensor system with a compact monolithic elastic element (EE) is designed and developed to detect the tangential cutting forces Fx, Fy and Fz (i.e., forces along x-, y-, and z-axis) as well as the cutting moments Mx, My and Mz (i.e., moments about x-, y-, and z-axis) simultaneously. Optimal structural parameters of the EE are carefully designed via simulation-driven optimization. Moreover, a prototype sensor system is fabricated, which is applied to a 5-axis parallel kinematic machining center. Calibration experimental results demonstrate that the system is capable of measuring cutting forces and moments with good linearity while minimizing coupling error. Both the Finite Element Analysis (FEA) and calibration experimental studies validate the high performance of the proposed sensor system that is expected to be adopted into machining processes. Full article

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

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20 pages, 5967 KiB

Open AccessArticle

Optimization and Experimentation of Dual-Mass MEMS Gyroscope Quadrature Error Correction Methods

by Huiliang Cao^1,2,3, Hongsheng Li³, Zhiwei Kou^1,2, Yunbo Shi^1,2, Jun Tang^1,2, Zongmin Ma^1,2, Chong Shen^1,2,*

and Jun Liu^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

³ School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China

Sensors 2016, 16(1), 71; https://doi.org/10.3390/s16010071 - 7 Jan 2016

Cited by 59 | Viewed by 8402

Abstract

This paper focuses on an optimal quadrature error correction method for the dual-mass MEMS gyroscope, in order to reduce the long term bias drift. It is known that the coupling stiffness and demodulation error are important elements causing bias drift. The coupling stiffness [...] Read more.

This paper focuses on an optimal quadrature error correction method for the dual-mass MEMS gyroscope, in order to reduce the long term bias drift. It is known that the coupling stiffness and demodulation error are important elements causing bias drift. The coupling stiffness in dual-mass structures is analyzed. The experiment proves that the left and right masses’ quadrature errors are different, and the quadrature correction system should be arranged independently. The process leading to quadrature error is proposed, and the Charge Injecting Correction (CIC), Quadrature Force Correction (QFC) and Coupling Stiffness Correction (CSC) methods are introduced. The correction objects of these three methods are the quadrature error signal, force and the coupling stiffness, respectively. The three methods are investigated through control theory analysis, model simulation and circuit experiments, and the results support the theoretical analysis. The bias stability results based on CIC, QFC and CSC are 48 °/h, 9.9 °/h and 3.7 °/h, respectively, and this value is 38 °/h before quadrature error correction. The CSC method is proved to be the better method for quadrature correction, and it improves the Angle Random Walking (ARW) value, increasing it from 0.66 °/√h to 0.21 °/√h. The CSC system general test results show that it works well across the full temperature range, and the bias stabilities of the six groups’ output data are 3.8 °/h, 3.6 °/h, 3.4 °/h, 3.1 °/h, 3.0 °/h and 4.2 °/h, respectively, which proves the system has excellent repeatability. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 17045 KiB

Open AccessReview

Recognition of Activities of Daily Living with Egocentric Vision: A Review

by Thi-Hoa-Cuc Nguyen^*, Jean-Christophe Nebel

and Francisco Florez-Revuelta

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

Sensors 2016, 16(1), 72; https://doi.org/10.3390/s16010072 - 7 Jan 2016

Cited by 98 | Viewed by 12790

Abstract

Video-based recognition of activities of daily living (ADLs) is being used in ambient assisted living systems in order to support the independent living of older people. However, current systems based on cameras located in the environment present a number of problems, such as [...] Read more.

Video-based recognition of activities of daily living (ADLs) is being used in ambient assisted living systems in order to support the independent living of older people. However, current systems based on cameras located in the environment present a number of problems, such as occlusions and a limited field of view. Recently, wearable cameras have begun to be exploited. This paper presents a review of the state of the art of egocentric vision systems for the recognition of ADLs following a hierarchical structure: motion, action and activity levels, where each level provides higher semantic information and involves a longer time frame. The current egocentric vision literature suggests that ADLs recognition is mainly driven by the objects present in the scene, especially those associated with specific tasks. However, although object-based approaches have proven popular, object recognition remains a challenge due to the intra-class variations found in unconstrained scenarios. As a consequence, the performance of current systems is far from satisfactory. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 5544 KiB

Open AccessArticle

Development of a Room Temperature SAW Methane Gas Sensor Incorporating a Supramolecular Cryptophane A Coating

by Wen Wang^1,*, Haoliang Hu¹, Xinlu Liu¹, Shitang He¹, Yong Pan², Caihong Zhang³ and Chuan Dong³

¹ State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, No. 21, BeiSiHuan West Road, Beijing 100190, China

² State Key Laboratory of NBC Protection for Civilian, Yangfang, Changping District, Beijing 102205, China

³ School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China

Sensors 2016, 16(1), 73; https://doi.org/10.3390/s16010073 - 7 Jan 2016

Cited by 35 | Viewed by 9302

Abstract

A new room temperature supra-molecular cryptophane A (CrypA)-coated surface acoustic wave (SAW) sensor for sensing methane gas is presented. The sensor is composed of differential resonator-oscillators, a supra-molecular CrypA coated along the acoustic propagation path, and a frequency signal acquisition module (FSAM). A [...] Read more.

A new room temperature supra-molecular cryptophane A (CrypA)-coated surface acoustic wave (SAW) sensor for sensing methane gas is presented. The sensor is composed of differential resonator-oscillators, a supra-molecular CrypA coated along the acoustic propagation path, and a frequency signal acquisition module (FSAM). A two-port SAW resonator configuration with low insertion loss, single resonation mode, and high quality factor was designed on a temperature-compensated ST-X quartz substrate, and as the feedback of the differntial oscillators. Prior to development, the coupling of modes (COM) simulation was conducted to predict the device performance. The supramolecular CrypA was synthesized from vanillyl alcohol using a double trimerisation method and deposited onto the SAW propagation path of the sensing resonators via different film deposition methods. Experiential results indicate the CrypA-coated sensor made using a dropping method exhibits higher sensor response compared to the unit prepared by the spinning approach because of the obviously larger surface roughness. Fast response and excellent repeatability were observed in gas sensing experiments, and the estimated detection limit and measured sensitivity are ~0.05% and ~204 Hz/%, respectively. Full article

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

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10 pages, 1669 KiB

Open AccessArticle

Low Dark-Current, High Current-Gain of PVK/ZnO Nanoparticles Composite-Based UV Photodetector by PN-Heterojunction Control

by Sang-Won Lee^1,†, Seung-Hwan Cha^1,†, Kyung-Jae Choi², Byoung-Ho Kang³, Jae-Sung Lee¹, Sae-Wan Kim¹

, Ju-Seong Kim¹, Hyun-Min Jeong¹, Sai-Anand Gopalan¹, Dae-Hyuk Kwon⁴ and Shin-Won Kang^1,*

¹ School of Electronics Engineering, College of IT engineering, Kyungpook National University, 80 Daehakro, Bukgu, 41566 Daegu, Korea

² Department of Sensor and Display Engineering, Kyungpook National University, 80 Daehakro, Bukgu, 41566 Daegu, Korea

³ Center for Functional Devices Fusion Platform, Kyungpook National University, 80 Daehakro, Bukgu, 41566 Daegu, Korea

⁴ Department of Electronics Engineering, Kyungil University, 50 Gamasil-Gil, Hayang-Eup, Gyeongbuk, 38428 Gyeongsan-Si, Korea

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 74; https://doi.org/10.3390/s16010074 - 7 Jan 2016

Cited by 31 | Viewed by 8521

Abstract

We propose a solution-processable ultraviolet (UV) photodetector with a pn-heterojunction hybrid photoactive layer (HPL) that is composed of poly-n-vinylcarbazole (PVK) as a p-type polymer and ZnO nanoparticles (NPs) as an n-type metal oxide. To observe the effective photo-inducing ability of the UV photodetector, [...] Read more.

We propose a solution-processable ultraviolet (UV) photodetector with a pn-heterojunction hybrid photoactive layer (HPL) that is composed of poly-n-vinylcarbazole (PVK) as a p-type polymer and ZnO nanoparticles (NPs) as an n-type metal oxide. To observe the effective photo-inducing ability of the UV photodetector, we analyzed the optical and electrical properties of HPL which is controlled by the doping concentration of n-type ZnO NPs in PVK matrix. Additionally, we confirmed that the optical properties of HPL dominantly depend on the ZnO NPs from the UV-vis absorption and the photoluminescence (PL) spectral measurements. This HPL can induce efficient charge transfer in the localized narrow pn-heterojunction domain and increases the photocurrent gain. It is essential that proper doping concentration of n-type ZnO NPs in polymer matrix is obtained to improve the performance of the UV photodetector. When the ZnO NPs are doped with the optimized concentration of 3.4 wt.%, the electrical properties of the photocurrent are significantly increased. The ratio of the photocurrent was approximately 10³ higher than that of the dark current. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 1273 KiB

Open AccessArticle

Authentication Based on Non-Interactive Zero-Knowledge Proofs for the Internet of Things

by Francisco Martín-Fernández^*

, Pino Caballero-Gil

and Cándido Caballero-Gil

Departament of Computer Engineering, University of La Laguna, 38271 La Laguna, Tenerife, Spain

Sensors 2016, 16(1), 75; https://doi.org/10.3390/s16010075 - 7 Jan 2016

Cited by 32 | Viewed by 9573

Abstract

This paper describes the design and analysis of a new scheme for the authenticated exchange of confidential information in insecure environments within the Internet of Things, which allows a receiver of a message to authenticate the sender and compute a secret key shared [...] Read more.

This paper describes the design and analysis of a new scheme for the authenticated exchange of confidential information in insecure environments within the Internet of Things, which allows a receiver of a message to authenticate the sender and compute a secret key shared with it. The proposal is based on the concept of a non-interactive zero-knowledge proof, so that in a single communication, relevant data may be inferred to verify the legitimacy of the sender. Besides, the new scheme uses the idea under the Diffie–Hellman protocol for the establishment of a shared secret key. The proposal has been fully developed for platforms built on the Android Open Source Project, so it can be used in any device or sensor with this operating system. This work provides a performance study of the implementation and a comparison between its promising results and others obtained with similar schemes. Full article

(This article belongs to the Special Issue Security and Privacy in Sensor Networks)

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16 pages, 3015 KiB

Open AccessArticle

Intelligent Condition Diagnosis Method Based on Adaptive Statistic Test Filter and Diagnostic Bayesian Network

by Ke Li¹, Qiuju Zhang^1,*, Kun Wang¹, Peng Chen² and Huaqing Wang³

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

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

³ School of Mechanical & Electrical Engineering, Beijing University of Chemical Technology, Chao Yang District, Beijing 100029, China

Sensors 2016, 16(1), 76; https://doi.org/10.3390/s16010076 - 8 Jan 2016

Cited by 15 | Viewed by 5773

Abstract

A new fault diagnosis method for rotating machinery based on adaptive statistic test filter (ASTF) and Diagnostic Bayesian Network (DBN) is presented in this paper. ASTF is proposed to obtain weak fault features under background noise, ASTF is based on statistic hypothesis testing [...] Read more.

A new fault diagnosis method for rotating machinery based on adaptive statistic test filter (ASTF) and Diagnostic Bayesian Network (DBN) is presented in this paper. ASTF is proposed to obtain weak fault features under background noise, ASTF is based on statistic hypothesis testing in the frequency domain to evaluate similarity between reference signal (noise signal) and original signal, and remove the component of high similarity. The optimal level of significance α is obtained using particle swarm optimization (PSO). To evaluate the performance of the ASTF, evaluation factor I_pq is also defined. In addition, a simulation experiment is designed to verify the effectiveness and robustness of ASTF. A sensitive evaluation method using principal component analysis (PCA) is proposed to evaluate the sensitiveness of symptom parameters (SPs) for condition diagnosis. By this way, the good SPs that have high sensitiveness for condition diagnosis can be selected. A three-layer DBN is developed to identify condition of rotation machinery based on the Bayesian Belief Network (BBN) theory. Condition diagnosis experiment for rolling element bearings demonstrates the effectiveness of the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 4575 KiB

Open AccessArticle

Global Calibration of Multiple Cameras Based on Sphere Targets

by Junhua Sun^1,†, Huabin He^1,† and Debing Zeng^2,*

¹ Ministry of Education Key Laboratory of Precision Opto-mechatronics Technology, Beihang University, Beijing 100191, China

² Department of Applied Science and Technology and Center for Microplasma Science and Technology, Saint Peter’s University, Jersey City, NJ 07036, USA

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 77; https://doi.org/10.3390/s16010077 - 8 Jan 2016

Cited by 32 | Viewed by 7688

Abstract

Global calibration methods for multi-camera system are critical to the accuracy of vision measurement. Proposed in this paper is such a method based on several groups of sphere targets and a precision auxiliary camera. Each camera to be calibrated observes a group of [...] Read more.

Global calibration methods for multi-camera system are critical to the accuracy of vision measurement. Proposed in this paper is such a method based on several groups of sphere targets and a precision auxiliary camera. Each camera to be calibrated observes a group of spheres (at least three), while the auxiliary camera observes all the spheres. The global calibration can be achieved after each camera reconstructs the sphere centers in its field of view. In the process of reconstructing a sphere center, a parameter equation is used to describe the sphere projection model. Theoretical analysis and computer simulation are carried out to analyze the factors that affect the calibration accuracy. Simulation results show that the parameter equation can largely improve the reconstruction accuracy. In the experiments, a two-camera system calibrated by our method is used to measure a distance about 578 mm, and the root mean squared error is within 0.14 mm. Furthermore, the experiments indicate that the method has simple operation and good flexibility, especially for the onsite multiple cameras without common field of view. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 5200 KiB

Open AccessArticle

Dynamic Vehicle Detection via the Use of Magnetic Field Sensors

by Vytautas Markevicius^*, Dangirutis Navikas, Mindaugas Zilys, Darius Andriukaitis

, Algimantas Valinevicius and Mindaugas Cepenas

Department of Electronics Engineering, Kaunas University of Technology, Studentu St. 50–418, LT-51368 Kaunas, Lithuania

Sensors 2016, 16(1), 78; https://doi.org/10.3390/s16010078 - 19 Jan 2016

Cited by 61 | Viewed by 11309

Abstract

The vehicle detection process plays the key role in determining the success of intelligent transport management system solutions. The measurement of distortions of the Earth’s magnetic field using magnetic field sensors served as the basis for designing a solution aimed at vehicle detection. [...] Read more.

The vehicle detection process plays the key role in determining the success of intelligent transport management system solutions. The measurement of distortions of the Earth’s magnetic field using magnetic field sensors served as the basis for designing a solution aimed at vehicle detection. In accordance with the results obtained from research into process modeling and experimentally testing all the relevant hypotheses an algorithm for vehicle detection using the state criteria was proposed. Aiming to evaluate all of the possibilities, as well as pros and cons of the use of anisotropic magnetoresistance (AMR) sensors in the transport flow control process, we have performed a series of experiments with various vehicles (or different series) from several car manufacturers. A comparison of 12 selected methods, based on either the process of determining the peak signal values and their concurrence in time whilst calculating the delay, or by measuring the cross-correlation of these signals, was carried out. It was established that the relative error can be minimized via the Z component cross-correlation and K_z criterion cross-correlation methods. The average relative error of vehicle speed determination in the best case did not exceed 1.5% when the distance between sensors was set to 2 m. Full article

(This article belongs to the Special Issue Magnetic Sensor Device-Part 2)

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14 pages, 3009 KiB

Open AccessArticle

Synthesis and Application of an Aldazine-Based Fluorescence Chemosensor for the Sequential Detection of Cu²⁺ and Biological Thiols in Aqueous Solution and Living Cells

by Hongmin Jia¹, Ming Yang¹, Qingtao Meng^1,*, Guangjie He², Yue Wang¹, Zhizhi Hu¹, Run Zhang³

and Zhiqiang Zhang^1,*

¹ Key Laboratory for Functional Material, Educational Department of Liaoning Province, University of Science and Technology Liaoning, Anshan 114051, China

² Department of Forensic Medicine, Xinxiang Medical University, Xinxiang, He‘nan 453003, China

³ Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia

Sensors 2016, 16(1), 79; https://doi.org/10.3390/s16010079 - 11 Jan 2016

Cited by 35 | Viewed by 7977

Abstract

A fluorescence chemosensor, 2-hydroxy-1-naphthaldehyde azine (HNA) was designed and synthesized for sequential detection of Cu²⁺ and biothiols. It was found that HNA can specifically bind to Cu²⁺ with 1:1 stoichiometry, accompanied with a dramatic fluorescence quenching and a remarkable [...] Read more.

A fluorescence chemosensor, 2-hydroxy-1-naphthaldehyde azine (HNA) was designed and synthesized for sequential detection of Cu²⁺ and biothiols. It was found that HNA can specifically bind to Cu²⁺ with 1:1 stoichiometry, accompanied with a dramatic fluorescence quenching and a remarkable bathochromic-shift of the absorbance peak in HEPES buffer. The generated HNA-Cu²⁺ ensemble displayed a “turn-on” fluorescent response specific for biothiols (Hcy, Cys and GSH) based on the displacement approach, giving a remarkable recovery of fluorescence and UV-Vis spectra. The detection limits of HNA-Cu²⁺ to Hcy, Cys and GSH were estimated to be 1.5 μM, 1.0 μM and 0.8 μM, respectively, suggesting that HNA-Cu²⁺ is sensitive enough for the determination of thiols in biological systems. The biocompatibility of HNA towards A549 human lung carcinoma cell, was evaluated by an MTT assay. The capability of HNA-Cu²⁺ to detect biothiols in live A549 cells was then demonstrated by a microscopy fluorescence imaging assay. Full article

(This article belongs to the Section Chemical Sensors)

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1 pages, 131 KiB

Open AccessCorrection

Correction: Yuan, G., et al. A Microgripper with a Post-Assembly Self-Locking Mechanism. Sensors 2015, 15, 20140-20151

by Guangmin Yuan, Weizheng Yuan, Yongcun Hao, Xiaoying Li and Honglong Chang^*

Key Laboratory of Micro/Nano Systems for Aerospace, Ministry of Education, Northwestern Polytechnical University, Xi’an 710072, China

Sensors 2016, 16(1), 80; https://doi.org/10.3390/s16010080 - 8 Jan 2016

Cited by 1 | Viewed by 3870

Abstract

The authors wish to make the following correction to this paper [1] [...] Full article

(This article belongs to the Section Physical Sensors)

13 pages, 2554 KiB

Open AccessArticle

Steady State Response Analysis of a Tubular Piezoelectric Print Head

by Jiaqing Chang^†

, Yaxin Liu^† and Bo Huang^*

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

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 81; https://doi.org/10.3390/s16010081 - 12 Jan 2016

Cited by 10 | Viewed by 5200

Abstract

In recent years, inkjet technology has played an important role in industrial materials printing and various sensors fabrication, but the mechanisms of the inkjet print head should be researched more elaborately. The steady state deformation analysis of a tubular piezoelectric print head, which [...] Read more.

In recent years, inkjet technology has played an important role in industrial materials printing and various sensors fabrication, but the mechanisms of the inkjet print head should be researched more elaborately. The steady state deformation analysis of a tubular piezoelectric print head, which can be classified as a plane strain problem because the radii of the tubes are considerably smaller than the lengths, is discussed in this paper. The geometric structure and the boundary conditions are all axisymmetric, so a one-dimensional mathematical model is constructed. By solving the model, the deformation field and stress field, as well as the electric potential distribution of the piezoelectric tube and glass tube, are obtained. The results show that the deformations are on the nanometer scale, the hoop stress is larger than the radial stress on the whole, and the potential is not linearly distributed along the radial direction. An experiment is designed to validate these computations. A discussion of the effect of the tubes’ thicknesses on the system deformation status is provided. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 1854 KiB

Open AccessArticle

A New Node Deployment and Location Dispatch Algorithm for Underwater Sensor Networks

by Peng Jiang^1,2,*, Jun Liu^1,2, Binfeng Ruan^1,2, Lurong Jiang³ and Feng Wu^1,2

¹ Key Lab for IOT and Information Fusion Technology of Zhejiang, Hangzhou 310018, China

² College of Automation, Hangzhou Dianzi University, Hangzhou 310018, China

³ School of Information Science and Technology, Zhejiang Sci-Tech University, Hangzhou 310018, China

Sensors 2016, 16(1), 82; https://doi.org/10.3390/s16010082 - 9 Jan 2016

Cited by 21 | Viewed by 6368

Abstract

Considering that deployment strategies for underwater sensor networks should contribute to fully connecting the networks, a Guaranteed Full Connectivity Node Deployment (GFCND) algorithm is proposed in this study. The GFCND algorithm attempts to deploy the coverage nodes according to the greedy iterative strategy, [...] Read more.

Considering that deployment strategies for underwater sensor networks should contribute to fully connecting the networks, a Guaranteed Full Connectivity Node Deployment (GFCND) algorithm is proposed in this study. The GFCND algorithm attempts to deploy the coverage nodes according to the greedy iterative strategy, after which the connectivity nodes are used to improve network connectivity and fully connect the whole network. Furthermore, a Location Dispatch Based on Command Nodes (LDBCN) algorithm is proposed, which accomplishes the location adjustment of the common nodes with the help of the SINK node and the command nodes. The command nodes then dispatch the common nodes. Simulation results show that the GFCND algorithm achieves a comparatively large coverage percentage and a fully connected network; furthermore, the LDBCN algorithm helps the common nodes preserve more total energy when they reach their destination locations. Full article

(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks 2016)

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19 pages, 1926 KiB

Open AccessArticle

An Energy-Efficient Skyline Query for Massively Multidimensional Sensing Data

by Yan Wang^1,2, Wei Wei³, Qingxu Deng^1,*, Wei Liu¹ and Houbing Song⁴

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

² School of Information, Liaoning University, Shenyang 110036, China

³ School of Computer Science and Engineering, Xi’an University of Technology, Xi’an 710048, China

⁴ Department of Electrical and Computer Engineering, West Virginia University, Montgomery, WV 25136, USA

Sensors 2016, 16(1), 83; https://doi.org/10.3390/s16010083 - 9 Jan 2016

Cited by 12 | Viewed by 5832

Abstract

Cyber physical systems (CPS) sense the environment based on wireless sensor networks. The sensing data of such systems present the characteristics of massiveness and multi-dimensionality. As one of the major monitoring methods used in in safe production monitoring and disaster early-warning applications, skyline [...] Read more.

Cyber physical systems (CPS) sense the environment based on wireless sensor networks. The sensing data of such systems present the characteristics of massiveness and multi-dimensionality. As one of the major monitoring methods used in in safe production monitoring and disaster early-warning applications, skyline query algorithms are extensively adopted for multiple-objective decision analysis of these sensing data. With the expansion of network sizes, the amount of sensing data increases sharply. Then, how to improve the query efficiency of skyline query algorithms and reduce the transmission energy consumption become pressing and difficult to accomplish issues. Therefore, this paper proposes a new energy-efficient skyline query method for massively multidimensional sensing data. First, the method uses a node cut strategy to dynamically generate filtering tuples with little computational overhead when collecting query results instead of issuing queries with filters. It can judge the domination relationship among different nodes, remove the detected data sets of dominated nodes that are irrelevant to the query, modify the query path dynamically, and reduce the data comparison and computational overhead. The efficient dynamic filter generated by this strategy uses little non-skyline data transmission in the network, and the transmission distance is very short. Second, our method also employs the tuple-cutting strategy inside the node and generates the local cutting tuples by the sub-tree with the node itself as the root node, which will be used to cut the detected data within the nodes of the sub-tree. Therefore, it can further control the non-skyline data uploading. A large number of experimental results show that our method can quickly return an overview of the monitored area and reduce the communication overhead. Additionally, it can shorten the response time and improve the efficiency of the query. Full article

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

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19 pages, 4352 KiB

Open AccessArticle

Design Optimization for the Measurement Accuracy Improvement of a Large Range Nanopositioning Stage

by Marta Torralba^1,*, José Antonio Yagüe-Fabra²

, José Antonio Albajez²

and Juan José Aguilar²

¹ Centro Universitario de la Defensa Zaragoza, Academia General Militar, Carretera Huesca s/n, Zaragoza 50090, Spain

² Instituto de Investigación en Ingeniería de Aragón, Universidad de Zaragoza, María de Luna 3, Zaragoza 50018, Spain

Sensors 2016, 16(1), 84; https://doi.org/10.3390/s16010084 - 11 Jan 2016

Cited by 24 | Viewed by 7086

Abstract

Both an accurate machine design and an adequate metrology loop definition are critical factors when precision positioning represents a key issue for the final system performance. This article discusses the error budget methodology as an advantageous technique to improve the measurement accuracy of [...] Read more.

Both an accurate machine design and an adequate metrology loop definition are critical factors when precision positioning represents a key issue for the final system performance. This article discusses the error budget methodology as an advantageous technique to improve the measurement accuracy of a 2D-long range stage during its design phase. The nanopositioning platform NanoPla is here presented. Its specifications, e.g., XY-travel range of 50 mm × 50 mm and sub-micrometric accuracy; and some novel designed solutions, e.g., a three-layer and two-stage architecture are described. Once defined the prototype, an error analysis is performed to propose improvement design features. Then, the metrology loop of the system is mathematically modelled to define the propagation of the different sources. Several simplifications and design hypothesis are justified and validated, including the assumption of rigid body behavior, which is demonstrated after a finite element analysis verification. The different error sources and their estimated contributions are enumerated in order to conclude with the final error values obtained from the error budget. The measurement deviations obtained demonstrate the important influence of the working environmental conditions, the flatness error of the plane mirror reflectors and the accurate manufacture and assembly of the components forming the metrological loop. Thus, a temperature control of ±0.1 °C results in an acceptable maximum positioning error for the developed NanoPla stage, i.e., 41 nm, 36 nm and 48 nm in X-, Y- and Z-axis, respectively. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 7089 KiB

Open AccessArticle

A New Approach to Detection of Systematic Errors in Secondary Substation Monitoring Equipment Based on Short Term Load Forecasting

by Javier Moriano¹, Francisco Javier Rodríguez^1,*

, Pedro Martín¹, Jose Antonio Jiménez¹ and Branislav Vuksanovic²

¹ Department of Electronics, University of Alcalá, Alcalá de Henares, Madrid 28805, Spain

² School of Engineering, University of Portsmouth, Winston Churchill Ave, Portsmouth PO1 3HJ, UK

Sensors 2016, 16(1), 85; https://doi.org/10.3390/s16010085 - 12 Jan 2016

Cited by 5 | Viewed by 5189

Abstract

In recent years, Secondary Substations (SSs) are being provided with equipment that allows their full management. This is particularly useful not only for monitoring and planning purposes but also for detecting erroneous measurements, which could negatively affect the performance of the SS. On [...] Read more.

In recent years, Secondary Substations (SSs) are being provided with equipment that allows their full management. This is particularly useful not only for monitoring and planning purposes but also for detecting erroneous measurements, which could negatively affect the performance of the SS. On the other hand, load forecasting is extremely important since they help electricity companies to make crucial decisions regarding purchasing and generating electric power, load switching, and infrastructure development. In this regard, Short Term Load Forecasting (STLF) allows the electric power load to be predicted over an interval ranging from one hour to one week. However, important issues concerning error detection by employing STLF has not been specifically addressed until now. This paper proposes a novel STLF-based approach to the detection of gain and offset errors introduced by the measurement equipment. The implemented system has been tested against real power load data provided by electricity suppliers. Different gain and offset error levels are successfully detected. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 5733 KiB

Open AccessArticle

RAQ–A Random Forest Approach for Predicting Air Quality in Urban Sensing Systems

by Ruiyun Yu^1,*, Yu Yang², Leyou Yang¹, Guangjie Han³

and Oguti Ann Move¹

¹ Software College, Northeastern University, Shenyang 110819, China

² Department of Computer Science, Rutgers University, New Brunswick, NJ 08854, USA

³ Department of Internet of Things Engineering, Hohai University, Changzhou 213022, China

Sensors 2016, 16(1), 86; https://doi.org/10.3390/s16010086 - 9 Jan 2016

Cited by 172 | Viewed by 10197

Abstract

Air quality information such as the concentration of PM_2.5 is of great significance for human health and city management. It affects the way of traveling, urban planning, government policies and so on. However, in major cities there is typically only a limited [...] Read more.

Air quality information such as the concentration of PM_2.5 is of great significance for human health and city management. It affects the way of traveling, urban planning, government policies and so on. However, in major cities there is typically only a limited number of air quality monitoring stations. In the meantime, air quality varies in the urban areas and there can be large differences, even between closely neighboring regions. In this paper, a random forest approach for predicting air quality (RAQ) is proposed for urban sensing systems. The data generated by urban sensing includes meteorology data, road information, real-time traffic status and point of interest (POI) distribution. The random forest algorithm is exploited for data training and prediction. The performance of RAQ is evaluated with real city data. Compared with three other algorithms, this approach achieves better prediction precision. Exciting results are observed from the experiments that the air quality can be inferred with amazingly high accuracy from the data which are obtained from urban sensing. Full article

(This article belongs to the Section Sensor Networks)

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9 pages, 2368 KiB

Open AccessArticle

Silica Bottle Resonator Sensor for Refractive Index and Temperature Measurements

by Galina Nemova^1,* and Raman Kashyap^1,2

¹ Department of Engineering Physics, Polytechnique Montréal, P.O. Box 6079, Station Centre-ville, Montréal, QC H3T 1J4, Canada

² Department of Electrical Engineering, Polytechnique Montréal, P.O. Box 6079, Station Centre-ville, Montréal, QC H3T 1J4, Canada

Sensors 2016, 16(1), 87; https://doi.org/10.3390/s16010087 - 9 Jan 2016

Cited by 20 | Viewed by 5142

Abstract

We propose and theoretically demonstrate a bottle resonator sensor with a nanoscale altitude and with alength several of hundreds of microns made on the top of the fiber with a radius of tens microns for refractive index and temperature sensor applications. The whispering [...] Read more.

We propose and theoretically demonstrate a bottle resonator sensor with a nanoscale altitude and with alength several of hundreds of microns made on the top of the fiber with a radius of tens microns for refractive index and temperature sensor applications. The whispering gallery modes (WGMs) in the resonators can be excited with a taper fiber placed on the top of the resonator. These sensors can be considered as an alternative to fiber Bragg grating (FBG) sensors.The sensitivity of TM-polarized modes is higher than the sensitivity of the TE-polarized modes, but these values are comparable and both polarizations are suitable for sensor applications. The sensitivity ~150 (nm/RIU) can be reached with abottle resonator on the fiber with the radius 10 μm. It can be improved with theuse of a fiber with a smaller radius. The temperature sensitivity is found to be ~10 pm/K. The temperature sensitivity can decrease ~10% for a fiber with a radius r_co = 10 μm instead of a fiber with a radius r_co = 100 μm. These sensors have sensitivities comparable to FBG sensors. A bottle resonator sensor with a nanoscale altitude made on the top of the fiber can be easily integrated in any fiber scheme. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 3531 KiB

Open AccessArticle

Mobile Crowd Sensing for Traffic Prediction in Internet of Vehicles

by Jiafu Wan¹

, Jianqi Liu^2,*, Zehui Shao³, Athanasios V. Vasilakos⁴, Muhammad Imran⁵ and Keliang Zhou⁶

¹ School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China

² School of Information Engineering, Guangdong Mechanical & Electrical College, Guangzhou 510515, China

³ School of Information Science and Technology, Chengdu University, Chengdu 610106, China

⁴ Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology, Luleå 97187, Sweden

⁵ College of Computer and Information Sciences, King Saud University, Riyadh 11451, Saudi Arabia

⁶ School of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou 341000, China

Sensors 2016, 16(1), 88; https://doi.org/10.3390/s16010088 - 11 Jan 2016

Cited by 225 | Viewed by 18528

Abstract

The advances in wireless communication techniques, mobile cloud computing, automotive and intelligent terminal technology are driving the evolution of vehicle ad hoc networks into the Internet of Vehicles (IoV) paradigm. This leads to a change in the vehicle routing problem from a calculation [...] Read more.

The advances in wireless communication techniques, mobile cloud computing, automotive and intelligent terminal technology are driving the evolution of vehicle ad hoc networks into the Internet of Vehicles (IoV) paradigm. This leads to a change in the vehicle routing problem from a calculation based on static data towards real-time traffic prediction. In this paper, we first address the taxonomy of cloud-assisted IoV from the viewpoint of the service relationship between cloud computing and IoV. Then, we review the traditional traffic prediction approached used by both Vehicle to Infrastructure (V2I) and Vehicle to Vehicle (V2V) communications. On this basis, we propose a mobile crowd sensing technology to support the creation of dynamic route choices for drivers wishing to avoid congestion. Experiments were carried out to verify the proposed approaches. Finally, we discuss the outlook of reliable traffic prediction. Full article

(This article belongs to the Special Issue Mobile Sensor Computing: Theory and Applications)

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14 pages, 1655 KiB

Open AccessArticle

An Ensemble Successive Project Algorithm for Liquor Detection Using Near Infrared Sensor

by Fangfang Qu¹, Dong Ren^1,*, Jihua Wang^1,2, Zhong Zhang¹, Na Lu¹ and Lei Meng¹

¹ College of Computer and Information Technology, Three Gorges University, Yichang 443002, China

² Beijing Research Center for Agricultural Standards and Testing, Beijing 100097, China

Sensors 2016, 16(1), 89; https://doi.org/10.3390/s16010089 - 11 Jan 2016

Cited by 15 | Viewed by 6668

Abstract

Spectral analysis technique based on near infrared (NIR) sensor is a powerful tool for complex information processing and high precision recognition, and it has been widely applied to quality analysis and online inspection of agricultural products. This paper proposes a new method to [...] Read more.

Spectral analysis technique based on near infrared (NIR) sensor is a powerful tool for complex information processing and high precision recognition, and it has been widely applied to quality analysis and online inspection of agricultural products. This paper proposes a new method to address the instability of small sample sizes in the successive projections algorithm (SPA) as well as the lack of association between selected variables and the analyte. The proposed method is an evaluated bootstrap ensemble SPA method (EBSPA) based on a variable evaluation index (EI) for variable selection, and is applied to the quantitative prediction of alcohol concentrations in liquor using NIR sensor. In the experiment, the proposed EBSPA with three kinds of modeling methods are established to test their performance. In addition, the proposed EBSPA combined with partial least square is compared with other state-of-the-art variable selection methods. The results show that the proposed method can solve the defects of SPA and it has the best generalization performance and stability. Furthermore, the physical meaning of the selected variables from the near infrared sensor data is clear, which can effectively reduce the variables and improve their prediction accuracy. Full article

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

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21 pages, 5167 KiB

Open AccessArticle

Identification of Shearer Cutting Patterns Using Vibration Signals Based on a Least Squares Support Vector Machine with an Improved Fruit Fly Optimization Algorithm

by Lei Si^1,2

, Zhongbin Wang^1,*, Xinhua Liu¹

, Chao Tan¹, Ze Liu¹ and Jing Xu¹

¹ School of Mechatronic Engineering, China University of Mining & Technology, No. 1 Daxue Road, Xuzhou 221116, China

² School of Information and Electrical Engineering, China University of Mining & Technology, No. 1 Daxue Road, Xuzhou 221116, China

Sensors 2016, 16(1), 90; https://doi.org/10.3390/s16010090 - 12 Jan 2016

Cited by 36 | Viewed by 6339

Abstract

Shearers play an important role in fully mechanized coal mining face and accurately identifying their cutting pattern is very helpful for improving the automation level of shearers and ensuring the safety of coal mining. The least squares support vector machine (LSSVM) has been [...] Read more.

Shearers play an important role in fully mechanized coal mining face and accurately identifying their cutting pattern is very helpful for improving the automation level of shearers and ensuring the safety of coal mining. The least squares support vector machine (LSSVM) has been proven to offer strong potential in prediction and classification issues, particularly by employing an appropriate meta-heuristic algorithm to determine the values of its two parameters. However, these meta-heuristic algorithms have the drawbacks of being hard to understand and reaching the global optimal solution slowly. In this paper, an improved fly optimization algorithm (IFOA) to optimize the parameters of LSSVM was presented and the LSSVM coupled with IFOA (IFOA-LSSVM) was used to identify the shearer cutting pattern. The vibration acceleration signals of five cutting patterns were collected and the special state features were extracted based on the ensemble empirical mode decomposition (EEMD) and the kernel function. Some examples on the IFOA-LSSVM model were further presented and the results were compared with LSSVM, PSO-LSSVM, GA-LSSVM and FOA-LSSVM models in detail. The comparison results indicate that the proposed approach was feasible, efficient and outperformed the others. Finally, an industrial application example at the coal mining face was demonstrated to specify the effect of the proposed system. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 1526 KiB

Open AccessArticle

An Assessment of Three Different In Situ Oxygen Sensors for Monitoring Silage Production and Storage

by Guilin Shan^1,†, Yurui Sun^1,*,†, Menghua Li¹, Kerstin H. Jungbluth², Christian Maack², Wolfgang Buescher²

, Kai-Benjamin Schütt², Peter Boeker², Peter Schulze Lammers², Haiyang Zhou¹, Qiang Cheng¹ and Daokun Ma¹

¹ College of Information and Electrical Engineering, China Agricultural University, Key Lab of Agricultural Information Acquisition Technology, Ministry of Agriculture, 100083 Beijing, China

² Department of Agricultural Engineering, The University of Bonn, 53115 Bonn, Germany

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 91; https://doi.org/10.3390/s16010091 - 14 Jan 2016

Cited by 9 | Viewed by 8352

Abstract

Oxygen (O₂) concentration inside the substrate is an important measurement for silage-research and-practical management. In the laboratory gas chromatography is commonly employed for O₂ measurement. Among sensor-based techniques, accurate and reliable in situ measurement is rare because of high levels [...] Read more.

Oxygen (O₂) concentration inside the substrate is an important measurement for silage-research and-practical management. In the laboratory gas chromatography is commonly employed for O₂ measurement. Among sensor-based techniques, accurate and reliable in situ measurement is rare because of high levels of carbon dioxide (CO₂) generated by the introduction of O₂ in the silage. The presented study focused on assessing three types of commercial O₂ sensors, including Clark oxygen electrodes (COE), galvanic oxygen cell (GOC) sensors and the Dräger chip measurement system (DCMS). Laboratory cross calibration of O₂ versus CO₂ (each 0–15 vol.%) was made for the COE and the GOC sensors. All calibration results verified that O₂ measurements for both sensors were insensitive to CO₂. For the O₂ in situ measurement in silage, all O₂ sensors were first tested in two sealed barrels (diameter 35.7 cm; height: 60 cm) to monitor the O₂ depletion with respect to the ensiling process (Test-A). The second test (Test-B) simulated the silage unloading process by recording the O₂ penetration dynamics in three additional barrels, two covered by dry ice (0.6 kg or 1.2 kg of each) on the top surface and one without. Based on a general comparison of the experimental data, we conclude that each of these in situ sensor monitoring techniques for O₂ concentration in silage exhibit individual advantages and limitations. Full article

(This article belongs to the Special Issue The Use of New and/or Improved Materials for Sensing Applications)

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9 pages, 4545 KiB

Open AccessArticle

A Compact Fiber Inclinometer Using a Thin-Core Fiber with Incorporated an Air-Gap Microcavity Fiber Interferometer

by Jiacheng Li¹

, Xueguang Qiao^1,*, Qiangzhou Rong^1,* and An Sun²

¹ Physics Department, Northwest University, No.229, Taibai Road (North), Xi’an 710069, China

² International Institute for Urban Systems Engineering, Southeast University, PailouFour No. Two, Nanjing 210096, China

Sensors 2016, 16(1), 92; https://doi.org/10.3390/s16010092 - 12 Jan 2016

Cited by 7 | Viewed by 5597

Abstract

A compact fiber-optic inclinometer is proposed and experimentally demonstrated based on a Fabry-Perot interference (FFPI). The sensing head consists of a short segment of thin-core fiber (TCF) following with a piece of hollow-core fiber (HCF). High-order cladding modes have been excited because of [...] Read more.

A compact fiber-optic inclinometer is proposed and experimentally demonstrated based on a Fabry-Perot interference (FFPI). The sensing head consists of a short segment of thin-core fiber (TCF) following with a piece of hollow-core fiber (HCF). High-order cladding modes have been excited because of core diameter mismatch. A clear interference spectrum has been obtained as the consequence of interference among the reflected core modes and cladding modes. Fringe contrast of the interference spectrum is highly sensitive to fiber bending with direction independence, and good linearity has been observed during the bending range from 1° to 3° with a sensitivity of 2.71 dB/deg. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 2475 KiB

Open AccessArticle

A Sensitivity Enhanced MWCNT/PDMS Tactile Sensor Using Micropillars and Low Energy Ar⁺ Ion Beam Treatment

by Syed Azkar Ul Hasan^1,2, Youngdo Jung¹, Seonggi Kim¹, Cho-Long Jung¹, Sunjong Oh¹, Junhee Kim¹ and Hyuneui Lim^1,2,*

¹ Department of Nature-Inspired Nano Convergence Systems, Korea Institute of Machinery and Materials, Daejeon 34103, Korea

² Department of Nanobiotechnology, University of Science & Technology, Daejeon 34113, Korea

Sensors 2016, 16(1), 93; https://doi.org/10.3390/s16010093 - 12 Jan 2016

Cited by 26 | Viewed by 9668

Abstract

High sensitive flexible and wearable devices which can detect delicate touches have attracted considerable attentions from researchers for various promising applications. This research was aimed at enhancing the sensitivity of a MWCNT/PDMS piezoresistive tactile sensor through modification of its surface texture in the [...] Read more.

High sensitive flexible and wearable devices which can detect delicate touches have attracted considerable attentions from researchers for various promising applications. This research was aimed at enhancing the sensitivity of a MWCNT/PDMS piezoresistive tactile sensor through modification of its surface texture in the form of micropillars on MWCNT/PDMS film and subsequent low energy Ar⁺ ion beam treatment of the micropillars. The introduction of straight micropillars on the MWCNT/PDMS surface increased the sensitivity under gentle touch. Low energy ion beam treatment was performed to induce a stiff layer on the exposed surface of the micropillar structured MWCNT/PDMS film. The low energy ion bombardment stabilized the electrical properties of the MWCNT/PDMS surface and tuned the curvature of micropillars according to the treatment conditions. The straight micropillars which were treated by Ar⁺ ion with an incident angle of 0° demonstrated the enhanced sensitivity under normal pressure and the curved micropillars which were treated with Ar⁺ ion with an incident angle of 60° differentiated the direction of an applied shear pressure. The ion beam treatment on micropillar structured MWCNT/PDMS tactile sensors can thus be applied to reliable sensing under gentle touch with directional discrimination. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 508 KiB

Open AccessArticle

Wireless Relay Selection in Pocket Switched Networks Based on Spatial Regularity of Human Mobility

by Jianhui Huang^1,*

, Xiuzhen Cheng², Jingping Bi¹ and Biao Chen³

¹ Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100191, China

² Department of Computer Science, The George Washington University, Washington, DC 20052, USA

³ Department of Computer Information Science, University of Macau, Macau 999078, China

Sensors 2016, 16(1), 94; https://doi.org/10.3390/s16010094 - 18 Jan 2016

Cited by 6 | Viewed by 5512

Abstract

Pocket switched networks (PSNs) take advantage of human mobility to deliver data. Investigations on real-world trace data indicate that human mobility shows an obvious spatial regularity: a human being usually visits a few places at high frequencies. These most frequently visited places form [...] Read more.

Pocket switched networks (PSNs) take advantage of human mobility to deliver data. Investigations on real-world trace data indicate that human mobility shows an obvious spatial regularity: a human being usually visits a few places at high frequencies. These most frequently visited places form the home of a node, which is exploited in this paper to design two HomE based Relay selectiOn (HERO) algorithms. Both algorithms input single data copy into the network at any time. In the basic HERO, only the first node encountered by the source and whose home overlaps a destination’s home is selected as a relay while the enhanced HERO keeps finding more optimal relay that visits the destination’s home with higher probability. The two proposed algorithms only require the relays to exchange the information of their home and/or the visiting frequencies to their home when two nodes meet. As a result, the information update is reduced and there is no global status information that needs to be maintained. This causes light loads on relays because of the low communication cost and storage requirements. Additionally, only simple operations are needed in the two proposed algorithms, resulting in little computation overhead at relays. At last, a theoretical analysis is performed on some key metrics and then the real-world based simulations indicate that the two HERO algorithms are efficient and effective through employing only one or a few relays. Full article

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

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18 pages, 3886 KiB

Open AccessArticle

A Virtual Blind Cane Using a Line Laser-Based Vision System and an Inertial Measurement Unit

by Quoc Khanh Dang

, Youngjoon Chee, Duy Duong Pham and Young Soo Suh^*

Department of Electrical Engineering, University of Ulsan, Namgu, Ulsan 680-749, Korea

Sensors 2016, 16(1), 95; https://doi.org/10.3390/s16010095 - 13 Jan 2016

Cited by 40 | Viewed by 14525

Abstract

A virtual blind cane system for indoor application, including a camera, a line laser and an inertial measurement unit (IMU), is proposed in this paper. Working as a blind cane, the proposed system helps a blind person find the type of obstacle and [...] Read more.

A virtual blind cane system for indoor application, including a camera, a line laser and an inertial measurement unit (IMU), is proposed in this paper. Working as a blind cane, the proposed system helps a blind person find the type of obstacle and the distance to it. The distance from the user to the obstacle is estimated by extracting the laser coordinate points on the obstacle, as well as tracking the system pointing angle. The paper provides a simple method to classify the obstacle’s type by analyzing the laser intersection histogram. Real experimental results are presented to show the validity and accuracy of the proposed system. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 542 KiB

Open AccessArticle

Use of Piezoelectric Immunosensors for Detection of Interferon-Gamma Interaction with Specific Antibodies in the Presence of Released-Active Forms of Antibodies to Interferon-Gamma

by Elena Don^1,*, Olga Farafonova², Suzanna Pokhil¹, Darya Barykina¹, Marina Nikiforova¹, Darya Shulga¹, Alena Borshcheva¹, Sergey Tarasov¹, Tatyana Ermolaeva² and Oleg Epstein¹

¹ OOO “NPF “MATERIA MEDICA HOLDING”, 3rd Samotyochny per., 9, 127473 Moscow, Russia

² Lipetsk State Technical University, Moskovskaya ul, 30, 398006 Lipetsk, Russia

Sensors 2016, 16(1), 96; https://doi.org/10.3390/s16010096 - 20 Jan 2016

Cited by 25 | Viewed by 6725

Abstract

In preliminary ELISA studies where released-active forms (RAF) of antibodies (Abs) to interferon-gamma (IFNg) were added to the antigen-antibody system, a statistically significant difference in absorbance signals obtained in their presence in comparison to placebo was observed. A piezoelectric immunosensor assay was developed [...] Read more.

In preliminary ELISA studies where released-active forms (RAF) of antibodies (Abs) to interferon-gamma (IFNg) were added to the antigen-antibody system, a statistically significant difference in absorbance signals obtained in their presence in comparison to placebo was observed. A piezoelectric immunosensor assay was developed to support these data and investigate the effects of RAF Abs to IFNg on the specific interaction between Abs to IFNg and IFNg. The experimental conditions were designed and optimal electrode coating, detection circumstances and suitable chaotropic agents for electrode regeneration were selected. The developed technique was found to provide high repeatability, intermediate precision and specificity. The difference between the analytical signals of RAF Ab samples and those of the placebo was up to 50.8%, whereas the difference between non-specific controls and the placebo was within 5%–6%. Thus, the piezoelectric immunosensor as well as ELISA has the potential to be used for detecting the effects of RAF Abs to IFNg on the antigen-antibody interaction, which might be the result of RAF’s ability to modify the affinity of IFNg to specific/related Abs. Full article

(This article belongs to the Section Biosensors)

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18 pages, 3905 KiB

Open AccessArticle

Unmanned Aerial Vehicles (UAVs) and Artificial Intelligence Revolutionizing Wildlife Monitoring and Conservation

by Luis F. Gonzalez^1,*, Glen A. Montes¹, Eduard Puig¹, Sandra Johnson², Kerrie Mengersen² and Kevin J. Gaston³

¹ Australian Research Centre for Aerospace Automation (ARCAA), Queensland University of Technology (QUT), 2 George St, Brisbane QLD 4000, Australia

² ARC Centre of Excellence for Mathematical & Statistical Frontiers (ACEMS), Queensland University of Technology (QUT), 2 George St, Brisbane QLD 4000, Australia

³ Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall TR10 9EZ, UK

Sensors 2016, 16(1), 97; https://doi.org/10.3390/s16010097 - 14 Jan 2016

Cited by 389 | Viewed by 49426

Abstract

Surveying threatened and invasive species to obtain accurate population estimates is an important but challenging task that requires a considerable investment in time and resources. Estimates using existing ground-based monitoring techniques, such as camera traps and surveys performed on foot, are known to [...] Read more.

Surveying threatened and invasive species to obtain accurate population estimates is an important but challenging task that requires a considerable investment in time and resources. Estimates using existing ground-based monitoring techniques, such as camera traps and surveys performed on foot, are known to be resource intensive, potentially inaccurate and imprecise, and difficult to validate. Recent developments in unmanned aerial vehicles (UAV), artificial intelligence and miniaturized thermal imaging systems represent a new opportunity for wildlife experts to inexpensively survey relatively large areas. The system presented in this paper includes thermal image acquisition as well as a video processing pipeline to perform object detection, classification and tracking of wildlife in forest or open areas. The system is tested on thermal video data from ground based and test flight footage, and is found to be able to detect all the target wildlife located in the surveyed area. The system is flexible in that the user can readily define the types of objects to classify and the object characteristics that should be considered during classification. Full article

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

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23 pages, 4842 KiB

Open AccessArticle

Node Self-Deployment Algorithm Based on an Uneven Cluster with Radius Adjusting for Underwater Sensor Networks

by Peng Jiang^1,2,*, Yiming Xu^1,2 and Feng Wu^1,2

¹ College of Automation, Hangzhou Dianzi University, Hangzhou 310018, China

² Key Lab for IOT and Information Fusion Technology of Zhejiang, Hangzhou 310018, China

Sensors 2016, 16(1), 98; https://doi.org/10.3390/s16010098 - 14 Jan 2016

Cited by 19 | Viewed by 6344

Abstract

Existing move-restricted node self-deployment algorithms are based on a fixed node communication radius, evaluate the performance based on network coverage or the connectivity rate and do not consider the number of nodes near the sink node and the energy consumption distribution of the [...] Read more.

Existing move-restricted node self-deployment algorithms are based on a fixed node communication radius, evaluate the performance based on network coverage or the connectivity rate and do not consider the number of nodes near the sink node and the energy consumption distribution of the network topology, thereby degrading network reliability and the energy consumption balance. Therefore, we propose a distributed underwater node self-deployment algorithm. First, each node begins the uneven clustering based on the distance on the water surface. Each cluster head node selects its next-hop node to synchronously construct a connected path to the sink node. Second, the cluster head node adjusts its depth while maintaining the layout formed by the uneven clustering and then adjusts the positions of in-cluster nodes. The algorithm originally considers the network reliability and energy consumption balance during node deployment and considers the coverage redundancy rate of all positions that a node may reach during the node position adjustment. Simulation results show, compared to the connected dominating set (CDS) based depth computation algorithm, that the proposed algorithm can increase the number of the nodes near the sink node and improve network reliability while guaranteeing the network connectivity rate. Moreover, it can balance energy consumption during network operation, further improve network coverage rate and reduce energy consumption. Full article

(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks 2016)

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27 pages, 6032 KiB

Open AccessReview

Overview of Fiber Optic Sensor Technologies for Strain/Temperature Sensing Applications in Composite Materials

by Manjusha Ramakrishnan^1,*, Ginu Rajan², Yuliya Semenova¹ and Gerald Farrell¹

¹ Photonics Research Centre, School of Electrical and Electronic Engineering, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland

² School of Electrical, Computer and Telecommunications Engineering, University of Wollongong, New South Wales 2522, Australia

Sensors 2016, 16(1), 99; https://doi.org/10.3390/s16010099 - 15 Jan 2016

Cited by 337 | Viewed by 31727

Abstract

This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used [...] Read more.

This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 1883 KiB

Open AccessArticle

Random Forest-Based Recognition of Isolated Sign Language Subwords Using Data from Accelerometers and Surface Electromyographic Sensors

by Ruiliang Su, Xiang Chen^*, Shuai Cao and Xu Zhang

Department of Electronic Science and Technology, University of Science and Technology of China, Hefei 230027, China

Sensors 2016, 16(1), 100; https://doi.org/10.3390/s16010100 - 14 Jan 2016

Cited by 64 | Viewed by 9685

Abstract

Sign language recognition (SLR) has been widely used for communication amongst the hearing-impaired and non-verbal community. This paper proposes an accurate and robust SLR framework using an improved decision tree as the base classifier of random forests. This framework was used to recognize [...] Read more.

Sign language recognition (SLR) has been widely used for communication amongst the hearing-impaired and non-verbal community. This paper proposes an accurate and robust SLR framework using an improved decision tree as the base classifier of random forests. This framework was used to recognize Chinese sign language subwords using recordings from a pair of portable devices worn on both arms consisting of accelerometers (ACC) and surface electromyography (sEMG) sensors. The experimental results demonstrated the validity of the proposed random forest-based method for recognition of Chinese sign language (CSL) subwords. With the proposed method, 98.25% average accuracy was obtained for the classification of a list of 121 frequently used CSL subwords. Moreover, the random forests method demonstrated a superior performance in resisting the impact of bad training samples. When the proportion of bad samples in the training set reached 50%, the recognition error rate of the random forest-based method was only 10.67%, while that of a single decision tree adopted in our previous work was almost 27.5%. Our study offers a practical way of realizing a robust and wearable EMG-ACC-based SLR systems. Full article

(This article belongs to the Section Physical Sensors)

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8 pages, 529 KiB

Open AccessArticle

A Terrestrial Single Chamber Microbial Fuel Cell-based Biosensor for Biochemical Oxygen Demand of Synthetic Rice Washed Wastewater

by Washington Logroño^1,2,*,†, Alex Guambo¹, Mario Pérez¹, Abudukeremu Kadier³

and Celso Recalde^1,4,†

¹ Centro de Investigación de Energías Alternativas y Ambiente, Facultad de Ciencias, Escuela Superior Politécnica de Chimborazo (ESPOCH), Panamericana Sur Km 1 ½, Chimborazo EC060155, Ecuador

² Faculty of Science and Informatics, University of Szeged, Közép fasor 52, Szeged H-6726, Hungary

³ Department of Chemical and Process Engineering, Faculty of Engineering & Built Environment, National University of Malaysia (UKM), UKM Bangi, Selangor 43600, Malaysia

⁴ Escuela de Ingeniería Ambiental, Universidad Nacional de Chimborazo, Chimborazo EC060103, Ecuador

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 101; https://doi.org/10.3390/s16010101 - 15 Jan 2016

Cited by 33 | Viewed by 6647

Abstract

Microbial fuel cells represent an innovative technology which allow simultaneous waste treatment, electricity production, and environmental monitoring. This study provides a preliminary investigation of the use of terrestrial Single chamber Microbial Fuel Cells (SMFCs) as biosensors. Three cells were created using Andean soil, [...] Read more.

Microbial fuel cells represent an innovative technology which allow simultaneous waste treatment, electricity production, and environmental monitoring. This study provides a preliminary investigation of the use of terrestrial Single chamber Microbial Fuel Cells (SMFCs) as biosensors. Three cells were created using Andean soil, each one for monitoring a BOD concentration of synthetic washed rice wastewater (SRWW) of 10, 100, and 200 mg/L for SMFC1, SMFC2 and SMFC3, respectively. The results showed transient, exponential, and steady stages in the SMFCs. The maximum open circuit voltage (OCV) peaks were reached during the elapsed time of the transient stages, according to the tested BOD concentrations. A good linearity between OCV and time was observed in the increasing stage. The average OCV in this stage increased independently of the tested concentrations. SMFC1 required less time than SMFC2 to reach the steady stage, suggesting the BOD concentration is an influencing factor in SMFCs, and SMFC3 did not reach it. The OCV ratios were between 40.6–58.8 mV and 18.2–32.9 mV for SMFC1 and SMFC2. The reproducibility of the SMFCs was observed in four and three cycles for SMFC1 and SMFC2, respectively. The presented SMFCs had a good response and reproducibility as biosensor devices, and could be an alternative for environmental monitoring. Full article

(This article belongs to the Section Biosensors)

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19 pages, 6261 KiB

Open AccessArticle

Drivers’ Visual Behavior-Guided RRT Motion Planner for Autonomous On-Road Driving

by Mingbo Du^1,2, Tao Mei², Huawei Liang², Jiajia Chen², Rulin Huang^1,2 and Pan Zhao^2,*

¹ Department of Automation, University of Science and Technology of China, Hefei 230026, China

² Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230026, China

Sensors 2016, 16(1), 102; https://doi.org/10.3390/s16010102 - 15 Jan 2016

Cited by 30 | Viewed by 9975

Abstract

This paper describes a real-time motion planner based on the drivers’ visual behavior-guided rapidly exploring random tree (RRT) approach, which is applicable to on-road driving of autonomous vehicles. The primary novelty is in the use of the guidance of drivers’ visual search behavior [...] Read more.

This paper describes a real-time motion planner based on the drivers’ visual behavior-guided rapidly exploring random tree (RRT) approach, which is applicable to on-road driving of autonomous vehicles. The primary novelty is in the use of the guidance of drivers’ visual search behavior in the framework of RRT motion planner. RRT is an incremental sampling-based method that is widely used to solve the robotic motion planning problems. However, RRT is often unreliable in a number of practical applications such as autonomous vehicles used for on-road driving because of the unnatural trajectory, useless sampling, and slow exploration. To address these problems, we present an interesting RRT algorithm that introduces an effective guided sampling strategy based on the drivers’ visual search behavior on road and a continuous-curvature smooth method based on B-spline. The proposed algorithm is implemented on a real autonomous vehicle and verified against several different traffic scenarios. A large number of the experimental results demonstrate that our algorithm is feasible and efficient for on-road autonomous driving. Furthermore, the comparative test and statistical analyses illustrate that its excellent performance is superior to other previous algorithms. Full article

(This article belongs to the Special Issue Sensors for Autonomous Road Vehicles)

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16 pages, 5652 KiB

Open AccessArticle

Studies of Reduced Graphene Oxide and Graphite Oxide in the Aspect of Their Possible Application in Gas Sensors

by Sabina Drewniak^1,*, Roksana Muzyka², Agnieszka Stolarczyk³

, Tadeusz Pustelny¹, Michalina Kotyczka-Morańska² and Maciej Setkiewicz¹

¹ Department of Optoelectronics, Silesian University of Technology, 2 Akademicka Str., Gliwice 44-100, Poland

² Institute for Chemical Processing of Coal, 1 Zamkowa Str., Zabrze 41-803, Poland

³ Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, 9 Strzody Str., Gliwice 44-100, Poland

Sensors 2016, 16(1), 103; https://doi.org/10.3390/s16010103 - 15 Jan 2016

Cited by 301 | Viewed by 14750

Abstract

The paper presents the results of investigations on resistance structures based on graphite oxide (GRO) and graphene oxide (rGO). The subject matter of the investigations was thaw the sensitivity of the tested structures was affected by hydrogen, nitrogen dioxide and carbon dioxide. The [...] Read more.

The paper presents the results of investigations on resistance structures based on graphite oxide (GRO) and graphene oxide (rGO). The subject matter of the investigations was thaw the sensitivity of the tested structures was affected by hydrogen, nitrogen dioxide and carbon dioxide. The experiments were performed at a temperature range from 30 °C to 150 °C in two carrier gases: nitrogen and synthetic air. The measurements were also aimed at characterization of the graphite oxide and graphene oxide. In our measurements we used (among others) techniques such as: Atomic Force Microscopy (AFM); Scanning Electron Microscopy (SEM); Raman Spectroscopy (RS); Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Microscopy (XPS). The data resulting from the characterizations of graphite oxide and graphene oxide have made it possible to interpret the obtained results from the point of view of physicochemical changes occurring in these structures. Full article

(This article belongs to the Special Issue Graphene and 2D Material Bionanosensors: Chemistry Matters)

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21 pages, 478 KiB

Open AccessArticle

On Connected Target k-Coverage in Heterogeneous Wireless Sensor Networks

by Jiguo Yu^1,*, Ying Chen¹, Liran Ma², Baogui Huang¹ and Xiuzhen Cheng³

¹ School of Information Science and Engineering, Qufu Normal University, Rizhao 276826, Shandong, China

² Department of Computer Science, Texas Christian University, Fort Worth, TX 298850, USA

³ Department of Computer Science, The George Washington University, Washington, DC 20052, USA

Sensors 2016, 16(1), 104; https://doi.org/10.3390/s16010104 - 15 Jan 2016

Cited by 53 | Viewed by 7306

Abstract

Coverage and connectivity are two important performance evaluation indices for wireless sensor networks (WSNs). In this paper, we focus on the connected target k-coverage (CTC k ) problem in heterogeneous wireless sensor networks (HWSNs). A centralized connected target k-coverage algorithm (CCTC k ) [...] Read more.

Coverage and connectivity are two important performance evaluation indices for wireless sensor networks (WSNs). In this paper, we focus on the connected target k-coverage (CTC k ) problem in heterogeneous wireless sensor networks (HWSNs). A centralized connected target k-coverage algorithm (CCTC k ) and a distributed connected target k-coverage algorithm (DCTC k ) are proposed so as to generate connected cover sets for energy-efficient connectivity and coverage maintenance. To be specific, our proposed algorithms aim at achieving minimum connected target k-coverage, where each target in the monitored region is covered by at least k active sensor nodes. In addition, these two algorithms strive to minimize the total number of active sensor nodes and guarantee that each sensor node is connected to a sink, such that the sensed data can be forwarded to the sink. Our theoretical analysis and simulation results show that our proposed algorithms outperform a state-of-art connected k-coverage protocol for HWSNs. Full article

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

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21 pages, 1907 KiB

Open AccessArticle

Decision-Level Fusion of Spatially Scattered Multi-Modal Data for Nondestructive Inspection of Surface Defects

by René Heideklang^1,* and Parisa Shokouhi^2,*

¹ Division 8.5 Micro NDE, Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany

² Department of Civil and Environmental Engineering, The Pennsylvania State University, 215 Sackett Bldg., University Park, PA 16802, USA

Sensors 2016, 16(1), 105; https://doi.org/10.3390/s16010105 - 15 Jan 2016

Cited by 8 | Viewed by 5378

Abstract

This article focuses on the fusion of flaw indications from multi-sensor nondestructive materials testing. Because each testing method makes use of a different physical principle, a multi-method approach has the potential of effectively differentiating actual defect indications from the many false alarms, thus [...] Read more.

This article focuses on the fusion of flaw indications from multi-sensor nondestructive materials testing. Because each testing method makes use of a different physical principle, a multi-method approach has the potential of effectively differentiating actual defect indications from the many false alarms, thus enhancing detection reliability. In this study, we propose a new technique for aggregating scattered two- or three-dimensional sensory data. Using a density-based approach, the proposed method explicitly addresses localization uncertainties such as registration errors. This feature marks one of the major of advantages of this approach over pixel-based image fusion techniques. We provide guidelines on how to set all the key parameters and demonstrate the technique’s robustness. Finally, we apply our fusion approach to experimental data and demonstrate its capability to locate small defects by substantially reducing false alarms under conditions where no single-sensor method is adequate. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 2557 KiB

Open AccessArticle

Influences of an Aluminum Covering Layer on the Performance of Cross-Like Hall Devices

by Fei Lyu¹, Xinfu Liu², Yinjie Ding², Eng-Huat Toh², Zhenyan Zhang¹, Yifan Pan³, Zhen Wang¹, Chengjie Li¹, Li Li¹, Jin Sha¹ and Hongbing Pan^1,*

¹ School of Electronic Science & Engineering, Nanjing University, Nanjing 210093, China

² Globalfoundries Singapore, Singapore 738406, Singapore

³ Nanjing Foreign Language School, Nanjing 210008, China

Sensors 2016, 16(1), 106; https://doi.org/10.3390/s16010106 - 15 Jan 2016

Cited by 7 | Viewed by 5278

Abstract

This work studies the effects of an aluminum covering on the performance of cross-like Hall devices. Four different Hall sensor structures of various sizes were designed and fabricated. The sensitivity and offset of the Hall sensors, two key points impacting their performance, were [...] Read more.

This work studies the effects of an aluminum covering on the performance of cross-like Hall devices. Four different Hall sensor structures of various sizes were designed and fabricated. The sensitivity and offset of the Hall sensors, two key points impacting their performance, were characterized using a self-built measurement system. The work analyzes the influences of the aluminum covering on those two aspects of the performance. The aluminum layer covering mainly leads to an eddy-current effect in an unstable magnetic field and an additional depletion region above the active region. Those two points have influences on the sensitivity and the offset voltage, respectively. The analysis guides the designer whether to choose covering with an aluminum layer the active region of the Hall sensor as a method to reduce the flicker noise and to improve the stability of the Hall sensor. Because Hall devices, as a reference element, always suffer from a large dispersion, improving their stability is a crucial issue. Full article

(This article belongs to the Section Physical Sensors)

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29 pages, 4901 KiB

Open AccessReview

Integration of Body Sensor Networks and Vehicular Ad-hoc Networks for Traffic Safety

by Angelica Reyes-Muñoz^1,*

, Mari Carmen Domingo², Marco Antonio López-Trinidad³ and José Luis Delgado³

¹ Computer Architecture Department, UPC BarcelonaTech, Esteve Terradas, Castelldefels 7-08860, Spain

² Electrical Engineering Department, UPC BarcelonaTech, Esteve Terradas, Castelldefels 7-08860, Spain

³ Laboratorio Nacional de Informática Avanzada (LANIA), Monterrey IT Cluster, Technological Research and Innovation Park (PIIT), Km. 10 Autopista al Aeropuerto Internacional Mariano Escobedo, Monterrey-Nuevo León 66629, México

Sensors 2016, 16(1), 107; https://doi.org/10.3390/s16010107 - 15 Jan 2016

Cited by 46 | Viewed by 12769

Abstract

The emergence of Body Sensor Networks (BSNs) constitutes a new and fast growing trend for the development of daily routine applications. However, in the case of heterogeneous BSNs integration with Vehicular ad hoc Networks (VANETs) a large number of difficulties remain, that must [...] Read more.

The emergence of Body Sensor Networks (BSNs) constitutes a new and fast growing trend for the development of daily routine applications. However, in the case of heterogeneous BSNs integration with Vehicular ad hoc Networks (VANETs) a large number of difficulties remain, that must be solved, especially when talking about the detection of human state factors that impair the driving of motor vehicles. The main contributions of this investigation are principally three: (1) an exhaustive review of the current mechanisms to detect four basic physiological behavior states (drowsy, drunk, driving under emotional state disorders and distracted driving) that may cause traffic accidents is presented; (2) A middleware architecture is proposed. This architecture can communicate with the car dashboard, emergency services, vehicles belonging to the VANET and road or street facilities. This architecture seeks on the one hand to improve the car driving experience of the driver and on the other hand to extend security mechanisms for the surrounding individuals; and (3) as a proof of concept, an Android real-time attention low level detection application that runs in a next-generation smartphone is developed. The application features mechanisms that allow one to measure the degree of attention of a driver on the base of her/his EEG signals, establish wireless communication links via various standard wireless means, GPRS, Bluetooth and WiFi and issue alarms of critical low driver attention levels. Full article

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

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17 pages, 1528 KiB

Open AccessArticle

Building SDN-Based Agricultural Vehicular Sensor Networks Based on Extended Open vSwitch

by Tao Huang^1,2,*

, Siyu Yan^1,2, Fan Yang^1,2, Tian Pan¹ and Jiang Liu^1,2

¹ State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing 100876, China

² Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory, Shijiazhuang 050081, China

Sensors 2016, 16(1), 108; https://doi.org/10.3390/s16010108 - 19 Jan 2016

Cited by 16 | Viewed by 7880

Abstract

Software-defined vehicular sensor networks in agriculture, such as autonomous vehicle navigation based on wireless multi-sensor networks, can lead to more efficient precision agriculture. In SDN-based vehicle sensor networks, the data plane is simplified and becomes more efficient by introducing a centralized controller. However, [...] Read more.

Software-defined vehicular sensor networks in agriculture, such as autonomous vehicle navigation based on wireless multi-sensor networks, can lead to more efficient precision agriculture. In SDN-based vehicle sensor networks, the data plane is simplified and becomes more efficient by introducing a centralized controller. However, in a wireless environment, the main controller node may leave the sensor network due to the dynamic topology change or the unstable wireless signal, leaving the rest of network devices without control, e.g., a sensor node as a switch may forward packets according to stale rules until the controller updates the flow table entries. To solve this problem, this paper proposes a novel SDN-based vehicular sensor networks architecture which can minimize the performance penalty of controller connection loss. We achieve this by designing a connection state detection and self-learning mechanism. We build prototypes based on extended Open vSwitch and Ryu. The experimental results show that the recovery time from controller connection loss is under 100 ms and it keeps rule updating in real time with a stable throughput. This architecture enhances the survivability and stability of SDN-based vehicular sensor networks in precision agriculture. Full article

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

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10 pages, 2136 KiB

Open AccessArticle

Reduced Graphene Oxide Modified the Interdigitated Chain Electrode for an Insulin Sensor

by Ajay Kumar Yagati^1,2, Jinsoo Park² and Sungbo Cho^1,2,*

¹ Department of Biomedical Engineering, Gachon University, 191 Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Korea

² Gachon Advanced Institute for Health Science & Technology, Gachon University, 155 Get-Pearl-ro, Yeonsu-gu, Incheon 21999, Korea

Sensors 2016, 16(1), 109; https://doi.org/10.3390/s16010109 - 15 Jan 2016

Cited by 29 | Viewed by 7981

Abstract

Insulin is a key regulator in glucose homeostasis and its deficiency or alternations in the human body causes various types of diabetic disorders. In this paper, we present the development of a reduced graphene oxide (rGO) modified interdigitated chain electrode (ICE) for direct [...] Read more.

Insulin is a key regulator in glucose homeostasis and its deficiency or alternations in the human body causes various types of diabetic disorders. In this paper, we present the development of a reduced graphene oxide (rGO) modified interdigitated chain electrode (ICE) for direct capacitive detection of insulin. The impedance properties of rGO-ICE were characterized by equivalent circuit modeling. After an electrochemical deposition of rGO on ICE, the electrode was modified with self-assembled monolayers and insulin antibodies in order to achieve insulin binding reactions. The impedance spectra and capacitances were measured with respect to the concentrations of insulin and the capacitance change (ΔC) was analyzed to quantify insulin concentration. The antibody immobilized electrode showed an increment of ΔC according to the insulin concentration in human serum ranging from 1 ng/mL to 10 µg/mL. The proposed sensor is feasible for label-free and real-time measuring of the biomarker and for point-of-care diagnosis. Full article

(This article belongs to the Special Issue Graphene and 2D Material Bionanosensors: Chemistry Matters)

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20 pages, 9234 KiB

Open AccessArticle

Compensation Method of Natural Head Movement for Gaze Tracking System Using an Ultrasonic Sensor for Distance Measurement

by Dongwook Jung¹, Jong Man Lee¹, Su Yeong Gwon¹, Weiyuan Pan¹, Hyeon Chang Lee¹, Kang Ryoung Park^1,* and Hyun-Cheol Kim²

¹ Division of Electronics and Electrical Engineering, Dongguk University, 30, Pildong-ro 1-gil, Jung-gu, Seoul 100-715, Korea

² Electronics and Telecommunications Research Institute, 218 Gajeong-ro, Yuseong-gu, Daejeon 305-700, Korea

Sensors 2016, 16(1), 110; https://doi.org/10.3390/s16010110 - 16 Jan 2016

Cited by 18 | Viewed by 6939

Abstract

Most gaze tracking systems are based on the pupil center corneal reflection (PCCR) method using near infrared (NIR) illuminators. One advantage of the PCCR method is the high accuracy it achieves in gaze tracking because it compensates for the pupil center position based [...] Read more.

Most gaze tracking systems are based on the pupil center corneal reflection (PCCR) method using near infrared (NIR) illuminators. One advantage of the PCCR method is the high accuracy it achieves in gaze tracking because it compensates for the pupil center position based on the relative position of corneal specular reflection (SR). However, the PCCR method only works for user head movements within a limited range, and its performance is degraded by the natural movement of the user’s head. To overcome this problem, we propose a gaze tracking method using an ultrasonic sensor that is robust to the natural head movement of users. Experimental results demonstrate that with our compensation method the gaze tracking system is more robust to natural head movements compared to other systems without our method and commercial systems. Full article

(This article belongs to the Section Physical Sensors)

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23 pages, 3373 KiB

Open AccessArticle

Galileo: The Added Value for Integrity in Harsh Environments

by Daniele Borio^1,* and Ciro Gioia^2,*

¹ European Commission, Joint Research Centre (JRC), Institute for the Protection and Security of the Citizen (IPSC), Security Technology Assessment Unit, Via Enrico Fermi 2749, 21027 Ispra (VA), Italy

² Piksel Ltd Italian Branch, Via Ernesto Breda 176, 20126 Milano (MI), Italy

Sensors 2016, 16(1), 111; https://doi.org/10.3390/s16010111 - 16 Jan 2016

Cited by 21 | Viewed by 5919

Abstract

A global navigation satellite system (GNSS)-based navigation is a challenging task in a signal-degraded environments where GNSS signals are distorted by multipath and attenuated by fading effects: the navigation solution may be inaccurate or unavailable. A possible approach to improve accuracy and availability [...] Read more.

A global navigation satellite system (GNSS)-based navigation is a challenging task in a signal-degraded environments where GNSS signals are distorted by multipath and attenuated by fading effects: the navigation solution may be inaccurate or unavailable. A possible approach to improve accuracy and availability is the joint use of measurements from different GNSSs and quality check algorithms; this approach is investigated here using live GPS and Galileo signals. A modified receiver autonomous integrity monitoring (RAIM) algorithm, including geometry and separability checks, is proposed to detect and exclude erroneous measurements: the multi-constellation approach provides redundant measurements, and RAIM exploits them to exclude distorted observations. The synergy between combined GPS/Galileo navigation and RAIM is analyzed using live data; the performance is compared to the accuracy and availability of a GPS-only solution. The tests performed demonstrate that the methods developed are effective techniques for GNSS-based navigation in signal-degraded environments. The joint use of the multi-constellation approach and of modified RAIM algorithms improves the performance of the navigation system in terms of both accuracy and availability. Full article

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

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20 pages, 368 KiB

Open AccessArticle

A Time-Aware Routing Map for Indoor Evacuation

by Haifeng Zhao^* and Stephan Winter

Department of Infrastructure Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia

Sensors 2016, 16(1), 112; https://doi.org/10.3390/s16010112 - 18 Jan 2016

Cited by 21 | Viewed by 6474

Abstract

Knowledge of dynamic environments expires over time. Thus, using static maps of the environment for decision making is problematic, especially in emergency situations, such as evacuations. This paper suggests a fading memory model for mapping dynamic environments: a mechanism to put less trust [...] Read more.

Knowledge of dynamic environments expires over time. Thus, using static maps of the environment for decision making is problematic, especially in emergency situations, such as evacuations. This paper suggests a fading memory model for mapping dynamic environments: a mechanism to put less trust on older knowledge in decision making. The model has been assessed by simulating indoor evacuations, adopting and comparing various strategies in decision making. Results suggest that fading memory generally improves this decision making. Full article

(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)

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13 pages, 408 KiB

Open AccessArticle

Modeling Sensor Reliability in Fault Diagnosis Based on Evidence Theory

by Kaijuan Yuan¹, Fuyuan Xiao¹, Liguo Fei¹, Bingyi Kang¹ and Yong Deng^1,2,3,4,*

¹ School of Computer and Information Science, Southwest University, Chongqing 400715, China

² School of Electronic and Information, Northwestern Polytechnical University, Xi’an 710072, China

³ Big Data Decision Institute, Jinan University, Tianhe, Guangzhou 510632, China

⁴ Department of Civil & Environmental Engineering, School of Engineering, Vanderbilt University, Nashville, TN 37235, USA

Sensors 2016, 16(1), 113; https://doi.org/10.3390/s16010113 - 18 Jan 2016

Cited by 95 | Viewed by 7683

Abstract

Sensor data fusion plays an important role in fault diagnosis. Dempster–Shafer (D-R) evidence theory is widely used in fault diagnosis, since it is efficient to combine evidence from different sensors. However, under the situation where the evidence highly conflicts, it may obtain a [...] Read more.

Sensor data fusion plays an important role in fault diagnosis. Dempster–Shafer (D-R) evidence theory is widely used in fault diagnosis, since it is efficient to combine evidence from different sensors. However, under the situation where the evidence highly conflicts, it may obtain a counterintuitive result. To address the issue, a new method is proposed in this paper. Not only the statistic sensor reliability, but also the dynamic sensor reliability are taken into consideration. The evidence distance function and the belief entropy are combined to obtain the dynamic reliability of each sensor report. A weighted averaging method is adopted to modify the conflict evidence by assigning different weights to evidence according to sensor reliability. The proposed method has better performance in conflict management and fault diagnosis due to the fact that the information volume of each sensor report is taken into consideration. An application in fault diagnosis based on sensor fusion is illustrated to show the efficiency of the proposed method. The results show that the proposed method improves the accuracy of fault diagnosis from 81.19% to 89.48% compared to the existing methods. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 2864 KiB

Open AccessArticle

DC-Compensated Current Transformer

by Pavel Ripka^1,*

, Karel Draxler¹ and Renata Styblíková²

¹ Faculty of Electrical Engineering, Czech Technical University, Technicka 2, 166 27 Praha 6, Czech Republic

² Czech Metrology Institute, V Botanice 4, 150 72 Praha 5, Czech Republic

Sensors 2016, 16(1), 114; https://doi.org/10.3390/s16010114 - 20 Jan 2016

Cited by 20 | Viewed by 9432

Abstract

Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept [...] Read more.

Instrument current transformers (CTs) measure AC currents. The DC component in the measured current can saturate the transformer and cause gross error. We use fluxgate detection and digital feedback compensation of the DC flux to suppress the overall error to 0.15%. This concept can be used not only for high-end CTs with a nanocrystalline core, but it also works for low-cost CTs with FeSi cores. The method described here allows simultaneous measurements of the DC current component. Full article

(This article belongs to the Special Issue Magnetic Sensor Device-Part 2)

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25 pages, 2156 KiB

Open AccessArticle

Deep Convolutional and LSTM Recurrent Neural Networks for Multimodal Wearable Activity Recognition

by Francisco Javier Ordóñez^* and Daniel Roggen

Wearable Technologies, Sensor Technology Research Centre, University of Sussex, Brighton BN1 9RH, UK

Sensors 2016, 16(1), 115; https://doi.org/10.3390/s16010115 - 18 Jan 2016

Cited by 2168 | Viewed by 95480

Abstract

Human activity recognition (HAR) tasks have traditionally been solved using engineered features obtained by heuristic processes. Current research suggests that deep convolutional neural networks are suited to automate feature extraction from raw sensor inputs. However, human activities are made of complex sequences of [...] Read more.

Human activity recognition (HAR) tasks have traditionally been solved using engineered features obtained by heuristic processes. Current research suggests that deep convolutional neural networks are suited to automate feature extraction from raw sensor inputs. However, human activities are made of complex sequences of motor movements, and capturing this temporal dynamics is fundamental for successful HAR. Based on the recent success of recurrent neural networks for time series domains, we propose a generic deep framework for activity recognition based on convolutional and LSTM recurrent units, which: (i) is suitable for multimodal wearable sensors; (ii) can perform sensor fusion naturally; (iii) does not require expert knowledge in designing features; and (iv) explicitly models the temporal dynamics of feature activations. We evaluate our framework on two datasets, one of which has been used in a public activity recognition challenge. Our results show that our framework outperforms competing deep non-recurrent networks on the challenge dataset by 4% on average; outperforming some of the previous reported results by up to 9%. Our results show that the framework can be applied to homogeneous sensor modalities, but can also fuse multimodal sensors to improve performance. We characterise key architectural hyperparameters’ influence on performance to provide insights about their optimisation. Full article

(This article belongs to the Special Issue Advances on Data Transmission and Analysis for Wearable Sensors Systems)

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9 pages, 828 KiB

Open AccessArticle

Quantitative Evaluation System of Soft Neurological Signs for Children with Attention Deficit Hyperactivity Disorder

by Miki Kaneko^1,*, Yushiro Yamashita² and Keiji Iramina^1,3

¹ Graduate School of Systems Life Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka-Shi, Fukuoka 812-8582, Japan

² Department of Pediatrics and Child Health, Kurume University School of Medicine, 67 Asahi-Machi, Kurume-Shi, Fukuoka 830-0011, Japan

³ Faculty of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka-Shi, Fukuoka 819-0395, Japan

Sensors 2016, 16(1), 116; https://doi.org/10.3390/s16010116 - 18 Jan 2016

Cited by 8 | Viewed by 7385

Abstract

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by symptoms of inattention, hyperactivity, and impulsivity. Soft neurological signs (SNS) are minor neurological abnormalities in motor performance, and are used as one evaluation method for neurodevelopmental delays in children with ADHD. Our [...] Read more.

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by symptoms of inattention, hyperactivity, and impulsivity. Soft neurological signs (SNS) are minor neurological abnormalities in motor performance, and are used as one evaluation method for neurodevelopmental delays in children with ADHD. Our aim is to establish a quantitative evaluation system for children with ADHD. We focused on the arm movement called pronation and supination, which is one such soft neurological sign. Thirty three children with ADHD aged 7–11 years (27 males, six females) and twenty five adults participants aged 21–29 years old (19 males, six females) participated in our experiments. Our results suggested that the pronation and supination function in children with ADHD has a tendency to lag behind that of typically developing children by several years. From these results, our system has a possibility to objectively evaluate the neurodevelopmental delay of children with ADHD. Full article

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

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14 pages, 804 KiB

Open AccessArticle

The Effect of Personalization on Smartphone-Based Fall Detectors

by Carlos Medrano^1,*, Inmaculada Plaza¹, Raúl Igual¹, Ángel Sánchez¹ and Manuel Castro²

¹ EduQTech, E.U. Politécnica de Teruel, University of Zaragoza, c/Atarazana 2, 44003 Teruel, Spain

² Electrical, and Computer Engineering Department, Spanish University for Distant Education (UNED), C/ Juan del Rosal, 12, 28040 Madrid, Spain

Sensors 2016, 16(1), 117; https://doi.org/10.3390/s16010117 - 18 Jan 2016

Cited by 36 | Viewed by 7164

Abstract

The risk of falling is high among different groups of people, such as older people, individuals with Parkinson's disease or patients in neuro-rehabilitation units. Developing robust fall detectors is important for acting promptly in case of a fall. Therefore, in this study we [...] Read more.

The risk of falling is high among different groups of people, such as older people, individuals with Parkinson's disease or patients in neuro-rehabilitation units. Developing robust fall detectors is important for acting promptly in case of a fall. Therefore, in this study we propose to personalize smartphone-based detectors to boost their performance as compared to a non-personalized system. Four algorithms were investigated using a public dataset: three novelty detection algorithms—Nearest Neighbor (NN), Local Outlier Factor (LOF) and One-Class Support Vector Machine (OneClass-SVM)—and a traditional supervised algorithm, Support Vector Machine (SVM). The effect of personalization was studied for each subject by considering two different training conditions: data coming only from that subject or data coming from the remaining subjects. The area under the receiver operating characteristic curve (AUC) was selected as the primary figure of merit. The results show that there is a general trend towards the increase in performance by personalizing the detector, but the effect depends on the individual being considered. A personalized NN can reach the performance of a non-personalized SVM (average AUC of 0.9861 and 0.9795, respectively), which is remarkable since NN only uses activities of daily living for training. Full article

(This article belongs to the Special Issue Smartphone-Based Sensors for Non-Invasive Physiological Monitoring)

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25 pages, 6193 KiB

Open AccessArticle

Defence against Black Hole and Selective Forwarding Attacks for Medical WSNs in the IoT

by Avijit Mathur^*

, Thomas Newe

and Muzaffar Rao

Department of Electronic and Communication, University of Limerick, Limerick V94 T9PX, Ireland

Sensors 2016, 16(1), 118; https://doi.org/10.3390/s16010118 - 19 Jan 2016

Cited by 73 | Viewed by 10421

Abstract

Wireless sensor networks (WSNs) are being used to facilitate monitoring of patients in hospital and home environments. These systems consist of a variety of different components/sensors and many processes like clustering, routing, security, and self-organization. Routing is necessary for medical-based WSNs because it [...] Read more.

Wireless sensor networks (WSNs) are being used to facilitate monitoring of patients in hospital and home environments. These systems consist of a variety of different components/sensors and many processes like clustering, routing, security, and self-organization. Routing is necessary for medical-based WSNs because it allows remote data delivery and it facilitates network scalability in large hospitals. However, routing entails several problems, mainly due to the open nature of wireless networks, and these need to be addressed. This paper looks at two of the problems that arise due to wireless routing between the nodes and access points of a medical WSN (for IoT use): black hole and selective forwarding (SF) attacks. A solution to the former can readily be provided through the use of cryptographic hashes, while the latter makes use of a neighbourhood watch and threshold-based analysis to detect and correct SF attacks. The scheme proposed here is capable of detecting a selective forwarding attack with over 96% accuracy and successfully identifying the malicious node with 83% accuracy. Full article

(This article belongs to the Special Issue Security and Privacy in Sensor Networks)

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13 pages, 5763 KiB

Open AccessArticle

Mapping Vineyard Leaf Area Using Mobile Terrestrial Laser Scanners: Should Rows be Scanned On-the-Go or Discontinuously Sampled?

by Ignacio Del-Moral-Martínez^1,*, Joan R. Rosell-Polo^1,3,†

, Joaquim Company^1,†, Ricardo Sanz^1,3,†, Alexandre Escolà^1,3,†

, Joan Masip^1,†, José A. Martínez-Casasnovas^2,3,†

and Jaume Arnó^1,3,†

¹ Research Group on AgroICT & Precision Agriculture, Department of Agricultural and Forest Engineering, University of Lleida, Rovira Roure 191, Lleida 25198, Spain

² Research Group on AgroICT & Precision Agriculture, Department of Environmental and Soil Sciences, University of Lleida, Rovira Roure 191, Lleida 25198, Spain

³ Research Group on AgroICT & Precision Agriculture, Agrotecnio Center, Rovira Roure 191, Lleida 25198, Spain

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 119; https://doi.org/10.3390/s16010119 - 19 Jan 2016

Cited by 36 | Viewed by 8380

Abstract

The leaf area index (LAI) is defined as the one-side leaf area per unit ground area, and is probably the most widely used index to characterize grapevine vigor. However, LAI varies spatially within vineyard plots. Mapping and quantifying this variability is very important [...] Read more.

The leaf area index (LAI) is defined as the one-side leaf area per unit ground area, and is probably the most widely used index to characterize grapevine vigor. However, LAI varies spatially within vineyard plots. Mapping and quantifying this variability is very important for improving management decisions and agricultural practices. In this study, a mobile terrestrial laser scanner (MTLS) was used to map the LAI of a vineyard, and then to examine how different scanning methods (on-the-go or discontinuous systematic sampling) may affect the reliability of the resulting raster maps. The use of the MTLS allows calculating the enveloping vegetative area of the canopy, which is the sum of the leaf wall areas for both sides of the row (excluding gaps) and the projected upper area. Obtaining the enveloping areas requires scanning from both sides one meter length section along the row at each systematic sampling point. By converting the enveloping areas into LAI values, a raster map of the latter can be obtained by spatial interpolation (kriging). However, the user can opt for scanning on-the-go in a continuous way and compute 1-m LAI values along the rows, or instead, perform the scanning at discontinuous systematic sampling within the plot. An analysis of correlation between maps indicated that MTLS can be used discontinuously in specific sampling sections separated by up to 15 m along the rows. This capability significantly reduces the amount of data to be acquired at field level, the data storage capacity and the processing power of computers. Full article

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

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17 pages, 4350 KiB

Open AccessArticle

Pedestrian Navigation Using Foot-Mounted Inertial Sensor and LIDAR

by Duy Duong Pham and Young Soo Suh^*

Department of Electrical Engineering, University of Ulsan, Namgu, Ulsan 680-749, Korea

Sensors 2016, 16(1), 120; https://doi.org/10.3390/s16010120 - 19 Jan 2016

Cited by 33 | Viewed by 8123

Abstract

Foot-mounted inertial sensors can be used for indoor pedestrian navigation. In this paper, to improve the accuracy of pedestrian location, we propose a method using a distance sensor (LIDAR) in addition to an inertial measurement unit (IMU). The distance sensor is a time [...] Read more.

Foot-mounted inertial sensors can be used for indoor pedestrian navigation. In this paper, to improve the accuracy of pedestrian location, we propose a method using a distance sensor (LIDAR) in addition to an inertial measurement unit (IMU). The distance sensor is a time of flight range finder with 30 m measurement range (at 33.33 Hz). Using a distance sensor, walls on corridors are automatically detected. The detected walls are used to correct the heading of the pedestrian path. Through experiments, it is shown that the accuracy of the heading is significantly improved using the proposed algorithm. Furthermore, the system is shown to work robustly in indoor environments with many doors and passing people. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 7127 KiB

Open AccessArticle

Realtime Gas Emission Monitoring at Hazardous Sites Using a Distributed Point-Source Sensing Infrastructure

by Gianfranco Manes^1,*,†, Giovanni Collodi^1,†, Leonardo Gelpi^2,†, Rosanna Fusco², Giuseppe Ricci², Antonio Manes^3,† and Marco Passafiume¹

¹ Department of Information Engineering (DINFO), Università di Firenze, via Santa Marta 3 50139 Firenze, Italy

² Eni Spa; Piazzale Enrico Mattei, 1 00144 Roma, Italy

³ Netsens Srl, via S.Pertini 93 50019 Sesto Fiorentino (Fi), Italy

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 121; https://doi.org/10.3390/s16010121 - 20 Jan 2016

Cited by 28 | Viewed by 6894

Abstract

This paper describes a distributed point-source monitoring platform for gas level and leakage detection in hazardous environments. The platform, based on a wireless sensor network (WSN) architecture, is organised into sub-networks to be positioned in the plant’s critical areas; each sub-net includes a [...] Read more.

This paper describes a distributed point-source monitoring platform for gas level and leakage detection in hazardous environments. The platform, based on a wireless sensor network (WSN) architecture, is organised into sub-networks to be positioned in the plant’s critical areas; each sub-net includes a gateway unit wirelessly connected to the WSN nodes, hence providing an easily deployable, stand-alone infrastructure featuring a high degree of scalability and reconfigurability. Furthermore, the system provides automated calibration routines which can be accomplished by non-specialized maintenance operators without system reliability reduction issues. Internet connectivity is provided via TCP/IP over GPRS (Internet standard protocols over mobile networks) gateways at a one-minute sampling rate. Environmental and process data are forwarded to a remote server and made available to authenticated users through a user interface that provides data rendering in various formats and multi-sensor data fusion. The platform is able to provide real-time plant management with an effective; accurate tool for immediate warning in case of critical events. Full article

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

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12 pages, 4066 KiB

Open AccessArticle

Assessment of Three Tropospheric Delay Models (IGGtrop, EGNOS and UNB3m) Based on Precise Point Positioning in the Chinese Region

by Hongxing Zhang^1,2,*, Yunbin Yuan¹, Wei Li¹, Ying Li¹ and Yanju Chai¹

¹ State Key Laboratory of Geodesy and Earth’s Dynamics, Institute of Geodesy and Geophysics, No. 340 Xudong Road, Wuhan 430077, China

² University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China

Sensors 2016, 16(1), 122; https://doi.org/10.3390/s16010122 - 20 Jan 2016

Cited by 32 | Viewed by 6701

Abstract

Tropospheric delays are one of the main sources of errors in the Global Navigation Satellite System (GNSS). They are usually corrected by using tropospheric delay models, which makes the accuracy of the models rather critical for accurate positioning. To provide references for suitable [...] Read more.

Tropospheric delays are one of the main sources of errors in the Global Navigation Satellite System (GNSS). They are usually corrected by using tropospheric delay models, which makes the accuracy of the models rather critical for accurate positioning. To provide references for suitable models to be chosen for GNSS users in China, we conduct herein a comprehensive study of the performances of the IGGtrop, EGNOS and UNB3m models in China. Firstly, we assess the models using 5 years’ Global Positioning System (GPS) derived Zenith Tropospheric Delay (ZTD) series from 25 stations of the Crustal Movement Observation Network of China (CMONOC). Then we study the effects of the models on satellite positioning by using various Precise Point Positioning (PPP) cases with different tropospheric delay resolutions, the observation data processed in PPP is from 21 base stations of CMONOC for a whole year of 2012. The results show that: (1) the Root Mean Square (RMS) of the IGGtrop model is about 4.4 cm, which improves the accuracy of ZTD estimations by about 24% for EGNOS and 19% for UNB3m; (2) The positioning error in the vertical component of the PPP solution obtained by using the IGGtrop model is about 15.0 cm, which is about 30% and 21% smaller than those of the EGNOS and UNB3m models, respectively. In summary, the IGGtrop model achieves the best performance among the three models in the Chinese region. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 8221 KiB

Open AccessArticle

Analysis of BeiDou Satellite Measurements with Code Multipath and Geometry-Free Ionosphere-Free Combinations

by Qile Zhao¹, Guangxing Wang^1,*, Zhizhao Liu^2,*, Zhigang Hu¹, Zhiqiang Dai³ and Jingnan Liu¹

¹ GNSS Research Center, Wuhan University, No.129 Luoyu Road, Wuhan 430079, China

² Department of Land Surveying & Geo-Informatics (LSGI), The Hong Kong Polytechnic University (PolyU), 181 Chatham Road South, Hung Hom, Kowloon, Hong Kong, China

³ School of Geodesy and Geomatics, Wuhan University, No.129 Luoyu Road, Wuhan 430079, China

Sensors 2016, 16(1), 123; https://doi.org/10.3390/s16010123 - 20 Jan 2016

Cited by 53 | Viewed by 8338

Abstract

Using GNSS observable from some stations in the Asia-Pacific area, the carrier-to-noise ratio (CNR) and multipath combinations of BeiDou Navigation Satellite System (BDS), as well as their variations with time and/or elevation were investigated and compared with those of GPS and Galileo. Provided [...] Read more.

Using GNSS observable from some stations in the Asia-Pacific area, the carrier-to-noise ratio (CNR) and multipath combinations of BeiDou Navigation Satellite System (BDS), as well as their variations with time and/or elevation were investigated and compared with those of GPS and Galileo. Provided the same elevation, the CNR of B1 observables is the lowest among the three BDS frequencies, while B3 is the highest. The code multipath combinations of BDS inclined geosynchronous orbit (IGSO) and medium Earth orbit (MEO) satellites are remarkably correlated with elevation, and the systematic “V” shape trends could be eliminated through between-station-differencing or modeling correction. Daily periodicity was found in the geometry-free ionosphere-free (GFIF) combinations of both BDS geostationary Earth orbit (GEO) and IGSO satellites. The variation range of carrier phase GFIF combinations of GEO satellites is −2.0 to 2.0 cm. The periodicity of carrier phase GFIF combination could be significantly mitigated through between-station differencing. Carrier phase GFIF combinations of BDS GEO and IGSO satellites might also contain delays related to satellites. Cross-correlation suggests that the GFIF combinations’ time series of some GEO satellites might vary according to their relative geometries with the sun. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 9421 KiB

Open AccessArticle

A Pedestrian Detection Scheme Using a Coherent Phase Difference Method Based on 2D Range-Doppler FMCW Radar

by Eugin Hyun

, Young-Seok Jin and Jong-Hun Lee^*

Advanced Radar Technology (ART) Lab., Division of IoT and Robotics Convergence Research, DGIST, 333 Techno Jungang-daero, Hyeonpung-myeon, Dalseong-gun, Daegu 711-873, Korea

Sensors 2016, 16(1), 124; https://doi.org/10.3390/s16010124 - 20 Jan 2016

Cited by 78 | Viewed by 20776

Abstract

For an automotive pedestrian detection radar system, fast-ramp based 2D range-Doppler Frequency Modulated Continuous Wave (FMCW) radar is effective for distinguishing between moving targets and unwanted clutter. However, when a weak moving target such as a pedestrian exists together with strong clutter, the [...] Read more.

For an automotive pedestrian detection radar system, fast-ramp based 2D range-Doppler Frequency Modulated Continuous Wave (FMCW) radar is effective for distinguishing between moving targets and unwanted clutter. However, when a weak moving target such as a pedestrian exists together with strong clutter, the pedestrian may be masked by the side-lobe of the clutter even though they are notably separated in the Doppler dimension. To prevent this problem, one popular solution is the use of a windowing scheme with a weighting function. However, this method leads to a spread spectrum, so the pedestrian with weak signal power and slow Doppler may also be masked by the main-lobe of clutter. With a fast-ramp based FMCW radar, if the target is moving, the complex spectrum of the range- Fast Fourier Transform (FFT) is changed with a constant phase difference over ramps. In contrast, the clutter exhibits constant phase irrespective of the ramps. Based on this fact, in this paper we propose a pedestrian detection for highly cluttered environments using a coherent phase difference method. By detecting the coherent phase difference from the complex spectrum of the range-FFT, we first extract the range profile of the moving pedestrians. Then, through the Doppler FFT, we obtain the 2D range-Doppler map for only the pedestrian. To test the proposed detection scheme, we have developed a real-time data logging system with a 24 GHz FMCW transceiver. In laboratory tests, we verified that the signal processing results from the proposed method were much better than those expected from the conventional 2D FFT-based detection method. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 1030 KiB

Open AccessArticle

Non-Cooperative Target Imaging and Parameter Estimation with Narrowband Radar Echoes

by Chun-mao Yeh¹, Wei Zhou^2,*, Yao-bing Lu¹ and Jian Yang²

¹ Beijing Institute of Radio Measurement, Beijing 100039, China

² Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

Sensors 2016, 16(1), 125; https://doi.org/10.3390/s16010125 - 20 Jan 2016

Cited by 3 | Viewed by 5448

Abstract

This study focuses on the rotating target imaging and parameter estimation with narrowband radar echoes, which is essential for radar target recognition. First, a two-dimensional (2D) imaging model with narrowband echoes is established in this paper, and two images of the target are [...] Read more.

This study focuses on the rotating target imaging and parameter estimation with narrowband radar echoes, which is essential for radar target recognition. First, a two-dimensional (2D) imaging model with narrowband echoes is established in this paper, and two images of the target are formed on the velocity-acceleration plane at two neighboring coherent processing intervals (CPIs). Then, the rotating velocity (RV) is proposed to be estimated by utilizing the relationship between the positions of the scattering centers among two images. Finally, the target image is rescaled to the range-cross-range plane with the estimated rotational parameter. The validity of the proposed approach is confirmed using numerical simulations. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 4298 KiB

Open AccessArticle

EMD-Based Symbolic Dynamic Analysis for the Recognition of Human and Nonhuman Pyroelectric Infrared Signals

by Jiaduo Zhao^1,†, Weiguo Gong^1,*, Yuzhen Tang^2,† and Weihong Li¹

¹ Key Lab of Optoelectronic Technology and Systems, Chongqing University, 174 Shazheng Street, Chongqing 400044, China

² Technology Center of Sichuan Changhong Electric Co. Ltd, 199 Tianfu Road, Chengdu 610000, China

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 126; https://doi.org/10.3390/s16010126 - 20 Jan 2016

Cited by 11 | Viewed by 6961

Abstract

In this paper, we propose an effective human and nonhuman pyroelectric infrared (PIR) signal recognition method to reduce PIR detector false alarms. First, using the mathematical model of the PIR detector, we analyze the physical characteristics of the human and nonhuman PIR signals; [...] Read more.

In this paper, we propose an effective human and nonhuman pyroelectric infrared (PIR) signal recognition method to reduce PIR detector false alarms. First, using the mathematical model of the PIR detector, we analyze the physical characteristics of the human and nonhuman PIR signals; second, based on the analysis results, we propose an empirical mode decomposition (EMD)-based symbolic dynamic analysis method for the recognition of human and nonhuman PIR signals. In the proposed method, first, we extract the detailed features of a PIR signal into five symbol sequences using an EMD-based symbolization method, then, we generate five feature descriptors for each PIR signal through constructing five probabilistic finite state automata with the symbol sequences. Finally, we use a weighted voting classification strategy to classify the PIR signals with their feature descriptors. Comparative experiments show that the proposed method can effectively classify the human and nonhuman PIR signals and reduce PIR detector’s false alarms. Full article

(This article belongs to the Special Issue Infrared and THz Sensing and Imaging)

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11 pages, 2671 KiB

Open AccessArticle

Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System

by Xiang Cai^1,*, Martin Walgenbach², Malte Doerpmond², Peter Schulze Lammers² and Yurui Sun³

¹ School of Information Science and Technology, Beijing Forestry University, Beijing 100083, China

² Department of Agricultural Engineering, University of Bonn, 53115 Bonn, Germany

³ College of Information & Electrical Engineering, China Agricultural University, Beijing 100083, China

Sensors 2016, 16(1), 127; https://doi.org/10.3390/s16010127 - 20 Jan 2016

Cited by 8 | Viewed by 9705

Abstract

To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS) by which chemical concentration transport lag was greatly reduced. In this system, [...] Read more.

To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS) by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV) was utilized for injecting chemicals, driven by a pulse-width modulation (PWM) signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID) method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input–output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy. Full article

(This article belongs to the Section Physical Sensors)

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30 pages, 13314 KiB

Open AccessArticle

Vision-Based People Detection System for Heavy Machine Applications

by Vincent Fremont^1,*

, Manh Tuan Bui¹

, Djamal Boukerroui¹ and Pierrick Letort²

¹ Sorbonne Universités, Université de Technologie de Compiègne, CNRS, UMR 7253, Heudiasyc-CS 60 319, 60 203 Compiègne Cedex, France

² Technical Center for the Mechanical Industry (CETIM), 60300 Senlis, France

Sensors 2016, 16(1), 128; https://doi.org/10.3390/s16010128 - 20 Jan 2016

Cited by 17 | Viewed by 8711

Abstract

This paper presents a vision-based people detection system for improving safety in heavy machines. We propose a perception system composed of a monocular fisheye camera and a LiDAR. Fisheye cameras have the advantage of a wide field-of-view, but the strong distortions that they [...] Read more.

This paper presents a vision-based people detection system for improving safety in heavy machines. We propose a perception system composed of a monocular fisheye camera and a LiDAR. Fisheye cameras have the advantage of a wide field-of-view, but the strong distortions that they create must be handled at the detection stage. Since people detection in fisheye images has not been well studied, we focus on investigating and quantifying the impact that strong radial distortions have on the appearance of people, and we propose approaches for handling this specificity, adapted from state-of-the-art people detection approaches. These adaptive approaches nevertheless have the drawback of high computational cost and complexity. Consequently, we also present a framework for harnessing the LiDAR modality in order to enhance the detection algorithm for different camera positions. A sequential LiDAR-based fusion architecture is used, which addresses directly the problem of reducing false detections and computational cost in an exclusively vision-based system. A heavy machine dataset was built, and different experiments were carried out to evaluate the performance of the system. The results are promising, in terms of both processing speed and performance. Full article

(This article belongs to the Section Physical Sensors)

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7 pages, 1552 KiB

Open AccessArticle

Parallel Imaging of 3D Surface Profile with Space-Division Multiplexing

by Hyung Seok Lee¹, Soon-Woo Cho¹, Gyeong Hun Kim¹, Myung Yung Jeong¹, Young Jae Won^2,*

and Chang-Seok Kim^1,*

¹ Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 609-735, Korea

² Medical Device Development Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk 361-951, Korea

Sensors 2016, 16(1), 129; https://doi.org/10.3390/s16010129 - 21 Jan 2016

Cited by 3 | Viewed by 5326

Abstract

We have developed a modified optical frequency domain imaging (OFDI) system that performs parallel imaging of three-dimensional (3D) surface profiles by using the space division multiplexing (SDM) method with dual-area swept sourced beams. We have also demonstrated that 3D surface information for two [...] Read more.

We have developed a modified optical frequency domain imaging (OFDI) system that performs parallel imaging of three-dimensional (3D) surface profiles by using the space division multiplexing (SDM) method with dual-area swept sourced beams. We have also demonstrated that 3D surface information for two different areas could be well obtained in a same time with only one camera by our method. In this study, double field of views (FOVs) of 11.16 mm × 5.92 mm were achieved within 0.5 s. Height range for each FOV was 460 µm and axial and transverse resolutions were 3.6 and 5.52 µm, respectively. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 1988 KiB

Open AccessArticle

Interferometric Laser Scanner for Direction Determination

by Gennady Kaloshin^*,† and Igor Lukin^†

¹ V.E. Zuev Institute of Atmospheric Optics SB RAS, Academician Zuev Square 1, Tomsk 634055, Russia

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 130; https://doi.org/10.3390/s16010130 - 21 Jan 2016

Cited by 4 | Viewed by 4958

Abstract

In this paper, we explore the potential capabilities of new laser scanning-based method for direction determination. The method for fully coherent beams is extended to the case when interference pattern is produced in the turbulent atmosphere by two partially coherent sources. The performed [...] Read more.

In this paper, we explore the potential capabilities of new laser scanning-based method for direction determination. The method for fully coherent beams is extended to the case when interference pattern is produced in the turbulent atmosphere by two partially coherent sources. The performed theoretical analysis identified the conditions under which stable pattern may form on extended paths of 0.5–10 km in length. We describe a method for selecting laser scanner parameters, ensuring the necessary operability range in the atmosphere for any possible turbulence characteristics. The method is based on analysis of the mean intensity of interference pattern, formed by two partially coherent sources of optical radiation. Visibility of interference pattern is estimated as a function of propagation pathlength, structure parameter of atmospheric turbulence, and spacing of radiation sources, producing the interference pattern. It is shown that, when atmospheric turbulences are moderately strong, the contrast of interference pattern of laser scanner may ensure its applicability at ranges up to 10 km. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 2839 KiB

Open AccessArticle

Intravehicular, Short- and Long-Range Communication Information Fusion for Providing Safe Speed Warnings

by Felipe Jiménez^1,*

, Jose Eugenio Naranjo¹

, Francisco Serradilla¹, Elisa Pérez², María Jose Hernández², Trinidad Ruiz², José Javier Anaya¹ and Alberto Díaz¹

¹ University Institute for Automobile Research (INSIA), Ctra. Valencia, Km. 7, Madrid 28031, Spain

² Psychology Faculty, Universidad Complutense de Madrid, Campus de Somosaguas, Ctra. de Húmera, s/n, Pozuelo de Alarcón, Madrid 28223, Spain

Sensors 2016, 16(1), 131; https://doi.org/10.3390/s16010131 - 21 Jan 2016

Cited by 8 | Viewed by 6757

Abstract

Inappropriate speed is a relevant concurrent factor in many traffic accidents. Moreover, in recent years, traffic accidents numbers in Spain have fallen sharply, but this reduction has not been so significant on single carriageway roads. These infrastructures have less equipment than high-capacity roads, [...] Read more.

Inappropriate speed is a relevant concurrent factor in many traffic accidents. Moreover, in recent years, traffic accidents numbers in Spain have fallen sharply, but this reduction has not been so significant on single carriageway roads. These infrastructures have less equipment than high-capacity roads, therefore measures to reduce accidents on them should be implemented in vehicles. This article describes the development and analysis of the impact on the driver of a warning system for the safe speed on each road section in terms of geometry, the presence of traffic jams, weather conditions, type of vehicle and actual driving conditions. This system is based on an application for smartphones and includes knowledge of the vehicle position via Ground Positioning System (GPS), access to intravehicular information from onboard sensors through the Controller Area Network (CAN) bus, vehicle data entry by the driver, access to roadside information (short-range communications) and access to a centralized server with information about the road in the current and following sections of the route (long-range communications). Using this information, the system calculates the safe speed, recommends the appropriate speed in advance in the following sections and provides warnings to the driver. Finally, data are sent from vehicles to a server to generate new information to disseminate to other users or to supervise drivers’ behaviour. Tests in a driving simulator have been used to define the system warnings and Human Machine Interface (HMI) and final tests have been performed on real roads in order to analyze the effect of the system on driver behavior. Full article

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

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13 pages, 2301 KiB

Open AccessArticle

Vision-Based Georeferencing of GPR in Urban Areas

by Riccardo Barzaghi, Noemi Emanuela Cazzaniga^*

, Diana Pagliari and Livio Pinto

Department of Civil and Environmental Engineering (DICA)-Geodesy and Geomatics Section, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy

Sensors 2016, 16(1), 132; https://doi.org/10.3390/s16010132 - 21 Jan 2016

Cited by 13 | Viewed by 6027

Abstract

Ground Penetrating Radar (GPR) surveying is widely used to gather accurate knowledge about the geometry and position of underground utilities. The sensor arrays need to be coupled to an accurate positioning system, like a geodetic-grade Global Navigation Satellite System (GNSS) device. However, in [...] Read more.

Ground Penetrating Radar (GPR) surveying is widely used to gather accurate knowledge about the geometry and position of underground utilities. The sensor arrays need to be coupled to an accurate positioning system, like a geodetic-grade Global Navigation Satellite System (GNSS) device. However, in urban areas this approach is not always feasible because GNSS accuracy can be substantially degraded due to the presence of buildings, trees, tunnels, etc. In this work, a photogrammetric (vision-based) method for GPR georeferencing is presented. The method can be summarized in three main steps: tie point extraction from the images acquired during the survey, computation of approximate camera extrinsic parameters and finally a refinement of the parameter estimation using a rigorous implementation of the collinearity equations. A test under operational conditions is described, where accuracy of a few centimeters has been achieved. The results demonstrate that the solution was robust enough for recovering vehicle trajectories even in critical situations, such as poorly textured framed surfaces, short baselines, and low intersection angles. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 2725 KiB

Open AccessArticle

Analysis of a Segmented Annular Coplanar Capacitive Tilt Sensor with Increased Sensitivity

by Jiahao Guo, Pengcheng Hu^*

and Jiubin Tan

Department of Automation Measurement and Control Engineering, Harbin Institute of Technology, D-403 Science Park, 2 Yikuang Street, Harbin 150080, China

Sensors 2016, 16(1), 133; https://doi.org/10.3390/s16010133 - 21 Jan 2016

Cited by 18 | Viewed by 7765

Abstract

An investigation of a segmented annular coplanar capacitor is presented. We focus on its theoretical model, and a mathematical expression of the capacitance value is derived by solving a Laplace equation with Hankel transform. The finite element method is employed to verify the [...] Read more.

An investigation of a segmented annular coplanar capacitor is presented. We focus on its theoretical model, and a mathematical expression of the capacitance value is derived by solving a Laplace equation with Hankel transform. The finite element method is employed to verify the analytical result. Different control parameters are discussed, and each contribution to the capacitance value of the capacitor is obtained. On this basis, we analyze and optimize the structure parameters of a segmented coplanar capacitive tilt sensor, and three models with different positions of the electrode gap are fabricated and tested. The experimental result shows that the model (whose electrode-gap position is 10 mm from the electrode center) realizes a high sensitivity: 0.129 pF/° with a non-linearity of <0.4% FS (full scale of ±40°). This finding offers plenty of opportunities for various measurement requirements in addition to achieving an optimized structure in practical design. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 948 KiB

Open AccessArticle

A Machine Learning Framework for Gait Classification Using Inertial Sensors: Application to Elderly, Post-Stroke and Huntington’s Disease Patients

by Andrea Mannini^1,*, Diana Trojaniello², Andrea Cereatti²

and Angelo M. Sabatini¹

¹ The BioRobotics Institute, Scuola Superiore Sant’Anna, Pisa 56127, Italy

² Information Engineering Unit, POLCOMING Department, University of Sassari, Sassari 07100, Italy

Sensors 2016, 16(1), 134; https://doi.org/10.3390/s16010134 - 21 Jan 2016

Cited by 203 | Viewed by 16055

Abstract

Machine learning methods have been widely used for gait assessment through the estimation of spatio-temporal parameters. As a further step, the objective of this work is to propose and validate a general probabilistic modeling approach for the classification of different pathological gaits. Specifically, [...] Read more.

Machine learning methods have been widely used for gait assessment through the estimation of spatio-temporal parameters. As a further step, the objective of this work is to propose and validate a general probabilistic modeling approach for the classification of different pathological gaits. Specifically, the presented methodology was tested on gait data recorded on two pathological populations (Huntington’s disease and post-stroke subjects) and healthy elderly controls using data from inertial measurement units placed at shank and waist. By extracting features from group-specific Hidden Markov Models (HMMs) and signal information in time and frequency domain, a Support Vector Machines classifier (SVM) was designed and validated. The 90.5% of subjects was assigned to the right group after leave-one-subject–out cross validation and majority voting. The long-term goal we point to is the gait assessment in everyday life to early detect gait alterations. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 903 KiB

Open AccessArticle

A Novel Photoelectrochemical Biosensor for Tyrosinase and Thrombin Detection

by Jiexia Chen^1,2, Yifan Liu¹ and Guang-Chao Zhao^1,*

¹ Anhui Key Laboratory of Chem-Biosensing, School of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, China

² Departement of Chemistry, Wannan Medical College, Wuhu 241002, China

Sensors 2016, 16(1), 135; https://doi.org/10.3390/s16010135 - 21 Jan 2016

Cited by 28 | Viewed by 7659

Abstract

A novel photoelectrochemical biosensor for step-by-step assay of tyrosinase and thrombin was fabricated based on the specific interactions between the designed peptide and the target enzymes. A peptide chain with a special sequence which contains a positively charged lysine-labeled terminal, tyrosine at the [...] Read more.

A novel photoelectrochemical biosensor for step-by-step assay of tyrosinase and thrombin was fabricated based on the specific interactions between the designed peptide and the target enzymes. A peptide chain with a special sequence which contains a positively charged lysine-labeled terminal, tyrosine at the other end and a cleavage site recognized by thrombin between them was designed. The designed peptide can be fixed on surface of the CdTe quantum dots (QDs)-modified indium-tin oxide (ITO) electrode through electrostatic attraction to construct the photoelectrochemical biosensor. The tyrosinase target can catalyze the oxidization of tyrosine by oxygen into ortho-benzoquinone residues, which results in a decrease in the sensor photocurrent. Subsequently, the cleavage site could be recognized and cut off by another thrombin target, restoring the sensor photocurrent. The decrease or increase of photocurrent in the sensor enables us to assay tyrosinase and thrombin. Thus, the detection of tyrosinase and thrombin can be achieved in the linear range from 2.6 to 32 μg/mL and from 4.5 to 100 μg/mL with detection limits of 1.5 μg/mL and 1.9 μg/mL, respectively. Most importantly, this strategy shall allow us to detect different classes of enzymes simultaneously by designing various enzyme-specific peptide substrates. Full article

(This article belongs to the Special Issue Microbial and Enzymatic Biosensors)

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35 pages, 925 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Sensors in 2015

by Sensors Editorial Office

MDPI AG, Klybeckstrasse 64, CH-4057 Basel, Switzerland

Sensors 2016, 16(1), 136; https://doi.org/10.3390/s16010136 - 21 Jan 2016

Viewed by 13251

Abstract

The editors of Sensors would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...] Full article

29 pages, 2641 KiB

Open AccessReview

Graphene: The Missing Piece for Cancer Diagnosis?

by Sandra M. A. Cruz^1,†

, André F. Girão^2,†

, Gil Gonçalves^2,†

and Paula A. A. P. Marques^2,*

¹ Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal

² Nanoengineering Research Group, TEMA, Department of Mechanical Engineering, University of Aveiro, Aveiro 3810-193, Portugal

^† These authors contributed equally to this work.

Sensors 2016, 16(1), 137; https://doi.org/10.3390/s16010137 - 21 Jan 2016

Cited by 41 | Viewed by 11490

Abstract

This paper reviews recent advances in graphene-based biosensors development in order to obtain smaller and more portable devices with better performance for earlier cancer detection. In fact, the potential of Graphene for sensitive detection and chemical/biological free-label applications results from its exceptional physicochemical [...] Read more.

This paper reviews recent advances in graphene-based biosensors development in order to obtain smaller and more portable devices with better performance for earlier cancer detection. In fact, the potential of Graphene for sensitive detection and chemical/biological free-label applications results from its exceptional physicochemical properties such as high electrical and thermal conductivity, aspect-ratio, optical transparency and remarkable mechanical and chemical stability. Herein we start by providing a general overview of the types of graphene and its derivatives, briefly describing the synthesis procedure and main properties. It follows the reference to different routes to engineer the graphene surface for sensing applications with organic biomolecules and nanoparticles for the development of advanced biosensing platforms able to detect/quantify the characteristic cancer biomolecules in biological fluids or overexpressed on cancerous cells surface with elevated sensitivity, selectivity and stability. We then describe the application of graphene in optical imaging methods such as photoluminescence and Raman imaging, electrochemical sensors for enzymatic biosensing, DNA sensing, and immunosensing. The bioquantification of cancer biomarkers and cells is finally discussed, particularly electrochemical methods such as voltammetry and amperometry which are generally adopted transducing techniques for the development of graphene based sensors for biosensing due to their simplicity, high sensitivity and low-cost. To close, we discuss the major challenges that graphene based biosensors must overcome in order to reach the necessary standards for the early detection of cancer biomarkers by providing reliable information about the patient disease stage. Full article

(This article belongs to the Special Issue Graphene and 2D Material Bionanosensors: Chemistry Matters)

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8 pages, 2593 KiB

Open AccessArticle

A Two Fiber Bragg Gratings Sensing System to Monitor the Torque of Rotating Shaft

by Yongjiao Wang^1,2, Lei Liang¹, Yinquan Yuan^1,*, Gang Xu¹ and Fang Liu¹

¹ National Engineering Laboratory for Fiber Optic Sensing Technology, Wuhan University of Technology, Wuhan 430070, China

² School of Computer Science and Engineering, Henan University of Urban Construction, Pingdingshan 467000, China

Sensors 2016, 16(1), 138; https://doi.org/10.3390/s16010138 - 21 Jan 2016

Cited by 17 | Viewed by 5768

Abstract

By fixing two FBGs on the surface of a rotating shaft along the direction of ±45° and using dynamic wavelength demodulation technology, we propose an optical fiber sensing system to monitor the driving torque and torsion angle of the rotating shaft. In theory, [...] Read more.

By fixing two FBGs on the surface of a rotating shaft along the direction of ±45° and using dynamic wavelength demodulation technology, we propose an optical fiber sensing system to monitor the driving torque and torsion angle of the rotating shaft. In theory, the dependence relation of the dynamic difference of central wavelengths on the torque and torsion angle of the rotating shaft has been deduced. To verify an optical fiber sensing system, a series of sensing experiments have been completed and the measured data are approximately consistent with the theoretical analysis. The difference of two central wavelengths can be expressed as the sum of two parts: a “DC” part and a harmonic “AC” part. The driving torque or torsion angle is linear with the “DC” part of the difference of two central wavelengths, the harmonic “AC” part, meaning the torsion angle vibration, illustrates that periodic vibration torque may be caused by inhomogeneous centrifugal forces or inhomogeneous additional torques produced by the driving system and the load. Full article

(This article belongs to the Section Physical Sensors)

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