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Editorial

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34 pages, 819 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Sensors in 2016

by Sensors Editorial Office

MDPI AG, St. Alban-Anlage 66, 4052 Basel, Switzerland

Sensors 2017, 17(1), 128; https://doi.org/10.3390/s17010128 - 10 Jan 2017

Viewed by 15248

Abstract

The editors of Sensors would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article

Research

Jump to: Editorial, Review, Other

27 pages, 33857 KiB

Open AccessArticle

A Unified Framework for Street-View Panorama Stitching

by Li Li¹, Jian Yao^1,*, Renping Xie¹, Menghan Xia¹ and Wei Zhang²

¹ School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China

² School of Control Science and Engineering, Shandong University, Jinan 250061, China

Sensors 2017, 17(1), 1; https://doi.org/10.3390/s17010001 - 22 Dec 2016

Cited by 83 | Viewed by 8327

Abstract

In this paper, we propose a unified framework to generate a pleasant and high-quality street-view panorama by stitching multiple panoramic images captured from the cameras mounted on the mobile platform. Our proposed framework is comprised of four major steps: image warping, color correction, [...] Read more.

In this paper, we propose a unified framework to generate a pleasant and high-quality street-view panorama by stitching multiple panoramic images captured from the cameras mounted on the mobile platform. Our proposed framework is comprised of four major steps: image warping, color correction, optimal seam line detection and image blending. Since the input images are captured without a precisely common projection center from the scenes with the depth differences with respect to the cameras to different extents, such images cannot be precisely aligned in geometry. Therefore, an efficient image warping method based on the dense optical flow field is proposed to greatly suppress the influence of large geometric misalignment at first. Then, to lessen the influence of photometric inconsistencies caused by the illumination variations and different exposure settings, we propose an efficient color correction algorithm via matching extreme points of histograms to greatly decrease color differences between warped images. After that, the optimal seam lines between adjacent input images are detected via the graph cut energy minimization framework. At last, the Laplacian pyramid blending algorithm is applied to further eliminate the stitching artifacts along the optimal seam lines. Experimental results on a large set of challenging street-view panoramic images captured form the real world illustrate that the proposed system is capable of creating high-quality panoramas. Full article

(This article belongs to the Section Remote Sensors)

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10 pages, 3935 KiB

Open AccessArticle

Graphene-Based Long-Period Fiber Grating Surface Plasmon Resonance Sensor for High-Sensitivity Gas Sensing

by Wei Wei^1,2,3,*

, Jinpeng Nong^1,3, Guiwen Zhang¹, Linlong Tang^3,4, Xiao Jiang¹, Na Chen¹, Suqin Luo², Guilian Lan¹ and Yong Zhu^1,*

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

² Chongqing Research Center for Advanced Materials, Chongqing Academy of Science and Technology, Chongqing 401123, China

³ Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 401122, China

⁴ Chongqing Engineering Research Center of Graphene Film Manufacturing, Chongqing 401329, China

Sensors 2017, 17(1), 2; https://doi.org/10.3390/s17010002 - 22 Dec 2016

Cited by 90 | Viewed by 10440

Abstract

A graphene-based long-period fiber grating (LPFG) surface plasmon resonance (SPR) sensor is proposed. A monolayer of graphene is coated onto the Ag film surface of the LPFG SPR sensor, which increases the intensity of the evanescent field on the surface of the fiber [...] Read more.

A graphene-based long-period fiber grating (LPFG) surface plasmon resonance (SPR) sensor is proposed. A monolayer of graphene is coated onto the Ag film surface of the LPFG SPR sensor, which increases the intensity of the evanescent field on the surface of the fiber and thereby enhances the interaction between the SPR wave and molecules. Such features significantly improve the sensitivity of the sensor. The experimental results demonstrate that the sensitivity of the graphene-based LPFG SPR sensor can reach 0.344 nm%⁻¹ for methane, which is improved 2.96 and 1.31 times with respect to the traditional LPFG sensor and Ag-coated LPFG SPR sensor, respectively. Meanwhile, the graphene-based LPFG SPR sensor exhibits excellent response characteristics and repeatability. Such a SPR sensing scheme offers a promising platform to achieve high sensitivity for gas-sensing applications. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 14429 KiB

Open AccessArticle

Measurement and Geometric Modelling of Human Spine Posture for Medical Rehabilitation Purposes Using a Wearable Monitoring System Based on Inertial Sensors

by Gheorghe-Daniel Voinea^*, Silviu Butnariu

and Gheorghe Mogan

Department of Automotive and Transport Engineering, Transilvania University of Brasov, 29 Eroilor Blvd, RO-500036 Brasov, Romania

Sensors 2017, 17(1), 3; https://doi.org/10.3390/s17010003 - 22 Dec 2016

Cited by 53 | Viewed by 11248

Abstract

This paper presents a mathematical model that can be used to virtually reconstruct the posture of the human spine. By using orientation angles from a wearable monitoring system based on inertial sensors, the model calculates and represents the curvature of the spine. Several [...] Read more.

This paper presents a mathematical model that can be used to virtually reconstruct the posture of the human spine. By using orientation angles from a wearable monitoring system based on inertial sensors, the model calculates and represents the curvature of the spine. Several hypotheses are taken into consideration to increase the model precision. An estimation of the postures that can be calculated is also presented. A non-invasive solution to identify the human back shape can help reducing the time needed for medical rehabilitation sessions. Moreover, it prevents future problems caused by poor posture. Full article

(This article belongs to the Special Issue Body Worn Behavior Sensing)

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12 pages, 4910 KiB

Open AccessArticle

Effects of Operating Temperature on Droplet Casting of Flexible Polymer/Multi-Walled Carbon Nanotube Composite Gas Sensors

by Jin-Chern Chiou^1,2, Chin-Cheng Wu^1,*, Yu-Chieh Huang²

, Shih-Cheng Chang³ and Tse-Mei Lin¹

¹ Department of Electrical and Computer Engineering, National Chiao Tung University, 1001 University Road, Hsinchu City 30010, Taiwan

² Institute of Electrical Control Engineering, National Chiao Tung University, 1001 University Road, Hsinchu City 30010, Taiwan

³ Institute of Biomedical Engineering, National Chiao Tung University, 1001 University Road, Hsinchu City 30010, Taiwan

Sensors 2017, 17(1), 4; https://doi.org/10.3390/s17010004 - 22 Dec 2016

Cited by 15 | Viewed by 10060

Abstract

This study examined the performance of a flexible polymer/multi-walled carbon nanotube (MWCNT) composite sensor array as a function of operating temperature. The response magnitudes of a cost-effective flexible gas sensor array equipped with a heater were measured with respect to five different operating [...] Read more.

This study examined the performance of a flexible polymer/multi-walled carbon nanotube (MWCNT) composite sensor array as a function of operating temperature. The response magnitudes of a cost-effective flexible gas sensor array equipped with a heater were measured with respect to five different operating temperatures (room temperature, 40 °C, 50 °C, 60 °C, and 70 °C) via impedance spectrum measurement and sensing response experiments. The selected polymers that were droplet cast to coat a MWCNT conductive layer to form two-layer polymer/MWCNT composite sensing films included ethyl cellulose (EC), polyethylene oxide (PEO), and polyvinylpyrrolidone (PVP). Electrical characterization of impedance, sensing response magnitude, and scanning electron microscope (SEM) morphology of each type of polymer/MWCNT composite film was performed at different operating temperatures. With respect to ethanol, the response magnitude of the sensor decreased with increasing operating temperatures. The results indicated that the higher operating temperature could reduce the response and influence the sensitivity of the polymer/MWCNT gas sensor array. The morphology of polymer/MWCNT composite films revealed that there were changes in the porous film after volatile organic compound (VOC) testing. Full article

(This article belongs to the Special Issue Gas Nanosensors)

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15 pages, 11735 KiB

Open AccessArticle

Selection of Shear Horizontal Wave Transducers for Robotic Nondestructive Inspection in Harsh Environments

by Sungho Choi, Hwanjeong Cho and Cliff J. Lissenden^*

Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA

Sensors 2017, 17(1), 5; https://doi.org/10.3390/s17010005 - 22 Dec 2016

Cited by 26 | Viewed by 6394

Abstract

Harsh environments and confined spaces require that nondestructive inspections be conducted with robotic systems. Ultrasonic guided waves are well suited for robotic systems because they can provide efficient volumetric coverage when inspecting for various types of damage, including cracks and corrosion. Shear horizontal [...] Read more.

Harsh environments and confined spaces require that nondestructive inspections be conducted with robotic systems. Ultrasonic guided waves are well suited for robotic systems because they can provide efficient volumetric coverage when inspecting for various types of damage, including cracks and corrosion. Shear horizontal guided waves are especially well suited for robotic inspection because they are sensitive to cracks oriented perpendicular or parallel to the wave propagation direction and can be generated with electromagnetic acoustic transducers (EMATs) and magnetostrictive transducers (MSTs). Both types of transducers are investigated for crack detection in a stainless steel plate. The MSTs require the robot to apply a compressive normal force that creates frictional force coupling. However, the coupling is observed to be very dependent upon surface roughness and surface debris. The EMATs are coupled through the Lorentz force and are thus noncontact, although they depend on the lift off between transducer and substrate. After comparing advantages and disadvantages of each transducer for robotic inspection the EMATs are selected for application to canisters that store used nuclear fuel. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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15 pages, 3419 KiB

Open AccessArticle

Cross View Gait Recognition Using Joint-Direct Linear Discriminant Analysis

by Jose Portillo-Portillo¹, Roberto Leyva², Victor Sanchez², Gabriel Sanchez-Perez¹, Hector Perez-Meana^1,*, Jesus Olivares-Mercado¹, Karina Toscano-Medina¹ and Mariko Nakano-Miyatake¹

¹ Instituto Politécnico Nacional, ESIME Culhuacan, 04430 Coyoacán, CDMX, Mexico

² Department of Computer Science, University of Warwick, CV4 7AL Coventry, UK

Sensors 2017, 17(1), 6; https://doi.org/10.3390/s17010006 - 22 Dec 2016

Cited by 17 | Viewed by 6046

Abstract

This paper proposes a view-invariant gait recognition framework that employs a unique view invariant model that profits from the dimensionality reduction provided by Direct Linear Discriminant Analysis (DLDA). The framework, which employs gait energy images (GEIs), creates a single joint model that accurately [...] Read more.

This paper proposes a view-invariant gait recognition framework that employs a unique view invariant model that profits from the dimensionality reduction provided by Direct Linear Discriminant Analysis (DLDA). The framework, which employs gait energy images (GEIs), creates a single joint model that accurately classifies GEIs captured at different angles. Moreover, the proposed framework also helps to reduce the under-sampling problem (USP) that usually appears when the number of training samples is much smaller than the dimension of the feature space. Evaluation experiments compare the proposed framework’s computational complexity and recognition accuracy against those of other view-invariant methods. Results show improvements in both computational complexity and recognition accuracy. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 2373 KiB

Open AccessArticle

Characteristics of the Fiber Laser Sensor System Based on Etched-Bragg Grating Sensing Probe for Determination of the Low Nitrate Concentration in Water

by Thanh Binh Pham^1,*

, Huy Bui¹, Huu Thang Le² and Van Hoi Pham¹

¹ Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Rd, Cau giay District, Hanoi 100000, Vietnam

² Small and Medium Enterprise Development and Support Center 1, Directorate for Standards, Metrology and Quality, 8 Hoang Quoc Viet Rd, Cau giay District, Hanoi 100000, Vietnam

Sensors 2017, 17(1), 7; https://doi.org/10.3390/s17010007 - 22 Dec 2016

Cited by 23 | Viewed by 7251

Abstract

The necessity of environmental protection has stimulated the development of many kinds of methods allowing the determination of different pollutants in the natural environment, including methods for determining nitrate in source water. In this paper, the characteristics of an etched fiber Bragg grating [...] Read more.

The necessity of environmental protection has stimulated the development of many kinds of methods allowing the determination of different pollutants in the natural environment, including methods for determining nitrate in source water. In this paper, the characteristics of an etched fiber Bragg grating (e-FBG) sensing probe—which integrated in fiber laser structure—are studied by numerical simulation and experiment. The proposed sensor is demonstrated for determination of the low nitrate concentration in a water environment. Experimental results show that this sensor could determine nitrate in water samples at a low concentration range of 0–80 ppm with good repeatability, rapid response, and average sensitivity of 3.5 × 10⁻³ nm/ppm with the detection limit of 3 ppm. The e-FBG sensing probe integrated in fiber laser demonstrates many advantages, such as a high resolution for wavelength shift identification, high optical signal-to-noise ratio (OSNR of 40 dB), narrow bandwidth of 0.02 nm that enhanced accuracy and precision of wavelength peak measurement, and capability for optical remote sensing. The obtained results suggested that the proposed e-FBG sensor has a large potential for the determination of low nitrate concentrations in water in outdoor field work. Full article

(This article belongs to the Section Physical Sensors)

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28 pages, 1850 KiB

Open AccessArticle

Small UAS-Based Wind Feature Identification System Part 1: Integration and Validation

by Leopoldo Rodriguez Salazar^*

, Jose A. Cobano and Anibal Ollero

Robotics, Vision and Control Group, Universidad de Sevilla, 41092 Sevilla, Spain

Sensors 2017, 17(1), 8; https://doi.org/10.3390/s17010008 - 23 Dec 2016

Cited by 27 | Viewed by 8277

Abstract

This paper presents a system for identification of wind features, such as gusts and wind shear. These are of particular interest in the context of energy-efficient navigation of Small Unmanned Aerial Systems (UAS). The proposed system generates real-time wind vector estimates and a [...] Read more.

This paper presents a system for identification of wind features, such as gusts and wind shear. These are of particular interest in the context of energy-efficient navigation of Small Unmanned Aerial Systems (UAS). The proposed system generates real-time wind vector estimates and a novel algorithm to generate wind field predictions. Estimations are based on the integration of an off-the-shelf navigation system and airspeed readings in a so-called direct approach. Wind predictions use atmospheric models to characterize the wind field with different statistical analyses. During the prediction stage, the system is able to incorporate, in a big-data approach, wind measurements from previous flights in order to enhance the approximations. Wind estimates are classified and fitted into a Weibull probability density function. A Genetic Algorithm (GA) is utilized to determine the shaping and scale parameters of the distribution, which are employed to determine the most probable wind speed at a certain position. The system uses this information to characterize a wind shear or a discrete gust and also utilizes a Gaussian Process regression to characterize continuous gusts. The knowledge of the wind features is crucial for computing energy-efficient trajectories with low cost and payload. Therefore, the system provides a solution that does not require any additional sensors. The system architecture presents a modular decentralized approach, in which the main parts of the system are separated in modules and the exchange of information is managed by a communication handler to enhance upgradeability and maintainability. Validation is done providing preliminary results of both simulations and Software-In-The-Loop testing. Telemetry data collected from real flights, performed in the Seville Metropolitan Area in Andalusia (Spain), was used for testing. Results show that wind estimation and predictions can be calculated at 1

Hz

and a wind map can be updated at 0.4

Hz

. Predictions show a convergence time with a 95% confidence interval of approximately 30

s

. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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13 pages, 483 KiB

Open AccessArticle

Energy and Quality Evaluation for Compressive Sensing of Fetal Electrocardiogram Signals

by Giulia Da Poian

, Denis Brandalise

, Riccardo Bernardini

and Roberto Rinaldo^*

Polytechnic Department of Engineering and Architecture, University of Udine, Via delle Scienze 206, 33100 Udine, Italy

Sensors 2017, 17(1), 9; https://doi.org/10.3390/s17010009 - 22 Dec 2016

Cited by 8 | Viewed by 5901

Abstract

This manuscript addresses the problem of non-invasive fetal Electrocardiogram (ECG) signal acquisition with low power/low complexity sensors. A sensor architecture using the Compressive Sensing (CS) paradigm is compared to a standard compression scheme using wavelets in terms of energy consumption vs. reconstruction quality, [...] Read more.

This manuscript addresses the problem of non-invasive fetal Electrocardiogram (ECG) signal acquisition with low power/low complexity sensors. A sensor architecture using the Compressive Sensing (CS) paradigm is compared to a standard compression scheme using wavelets in terms of energy consumption vs. reconstruction quality, and, more importantly, vs. performance of fetal heart beat detection in the reconstructed signals. We show in this paper that a CS scheme based on reconstruction with an over-complete dictionary has similar reconstruction quality to one based on wavelet compression. We also consider, as a more important figure of merit, the accuracy of fetal beat detection after reconstruction as a function of the sensor power consumption. Experimental results with an actual implementation in a commercial device show that CS allows significant reduction of energy consumption in the sensor node, and that the detection performance is comparable to that obtained from original signals for compression ratios up to about 75%. Full article

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

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17 pages, 12877 KiB

Open AccessArticle

Object-Based Paddy Rice Mapping Using HJ-1A/B Data and Temporal Features Extracted from Time Series MODIS NDVI Data

by Mrinal Singha^1,2, Bingfang Wu^2,*

and Miao Zhang²

¹ University of Chinese Academy of Sciences, Beijing 100049, China

² Division of Digital Agriculture, Institute of Remote Sensing and Digital Earth, Olympic Village Science Park, Beijing 100101, China

Sensors 2017, 17(1), 10; https://doi.org/10.3390/s17010010 - 22 Dec 2016

Cited by 33 | Viewed by 7321

Abstract

Accurate and timely mapping of paddy rice is vital for food security and environmental sustainability. This study evaluates the utility of temporal features extracted from coarse resolution data for object-based paddy rice classification of fine resolution data. The coarse resolution vegetation index data [...] Read more.

Accurate and timely mapping of paddy rice is vital for food security and environmental sustainability. This study evaluates the utility of temporal features extracted from coarse resolution data for object-based paddy rice classification of fine resolution data. The coarse resolution vegetation index data is first fused with the fine resolution data to generate the time series fine resolution data. Temporal features are extracted from the fused data and added with the multi-spectral data to improve the classification accuracy. Temporal features provided the crop growth information, while multi-spectral data provided the pattern variation of paddy rice. The achieved overall classification accuracy and kappa coefficient were 84.37% and 0.68, respectively. The results indicate that the use of temporal features improved the overall classification accuracy of a single-date multi-spectral image by 18.75% from 65.62% to 84.37%. The minimum sensitivity (MS) of the paddy rice classification has also been improved. The comparison showed that the mapped paddy area was analogous to the agricultural statistics at the district level. This work also highlighted the importance of feature selection to achieve higher classification accuracies. These results demonstrate the potential of the combined use of temporal and spectral features for accurate paddy rice classification. Full article

(This article belongs to the Special Issue Sensors and Smart Sensing of Agricultural Land Systems)

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26 pages, 3300 KiB

Open AccessArticle

A Multi-Sensor Fusion MAV State Estimation from Long-Range Stereo, IMU, GPS and Barometric Sensors

by Yu Song^1,2,*, Stephen Nuske¹ and Sebastian Scherer¹

¹ Robotics Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA

² School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing 100044, China

Sensors 2017, 17(1), 11; https://doi.org/10.3390/s17010011 - 22 Dec 2016

Cited by 48 | Viewed by 13522

Abstract

State estimation is the most critical capability for MAV (Micro-Aerial Vehicle) localization, autonomous obstacle avoidance, robust flight control and 3D environmental mapping. There are three main challenges for MAV state estimation: (1) it can deal with aggressive 6 DOF (Degree Of Freedom) motion; [...] Read more.

State estimation is the most critical capability for MAV (Micro-Aerial Vehicle) localization, autonomous obstacle avoidance, robust flight control and 3D environmental mapping. There are three main challenges for MAV state estimation: (1) it can deal with aggressive 6 DOF (Degree Of Freedom) motion; (2) it should be robust to intermittent GPS (Global Positioning System) (even GPS-denied) situations; (3) it should work well both for low- and high-altitude flight. In this paper, we present a state estimation technique by fusing long-range stereo visual odometry, GPS, barometric and IMU (Inertial Measurement Unit) measurements. The new estimation system has two main parts, a stochastic cloning EKF (Extended Kalman Filter) estimator that loosely fuses both absolute state measurements (GPS, barometer) and the relative state measurements (IMU, visual odometry), and is derived and discussed in detail. A long-range stereo visual odometry is proposed for high-altitude MAV odometry calculation by using both multi-view stereo triangulation and a multi-view stereo inverse depth filter. The odometry takes the EKF information (IMU integral) for robust camera pose tracking and image feature matching, and the stereo odometry output serves as the relative measurements for the update of the state estimation. Experimental results on a benchmark dataset and our real flight dataset show the effectiveness of the proposed state estimation system, especially for the aggressive, intermittent GPS and high-altitude MAV flight. Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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22 pages, 4969 KiB

Open AccessArticle

An Efficient Wireless Recharging Mechanism for Achieving Perpetual Lifetime of Wireless Sensor Networks

by Hongli Yu¹, Guilin Chen¹, Shenghui Zhao¹, Chih-Yung Chang^2,*

and Yu-Ting Chin²

¹ School of Computer and Information Engineering, Chuzhou University, Chuzhou 239000, China

² Department of Computer Science and Information Engineering, Tamkang University, New Taipei City 25137, Taiwan

Sensors 2017, 17(1), 13; https://doi.org/10.3390/s17010013 - 23 Dec 2016

Cited by 58 | Viewed by 4876

Abstract

Energy recharging has received much attention in recent years. Several recharging mechanisms were proposed for achieving perpetual lifetime of a given Wireless Sensor Network (WSN). However, most of them require a mobile recharger to visit each sensor and then perform the recharging task, [...] Read more.

Energy recharging has received much attention in recent years. Several recharging mechanisms were proposed for achieving perpetual lifetime of a given Wireless Sensor Network (WSN). However, most of them require a mobile recharger to visit each sensor and then perform the recharging task, which increases the length of the recharging path. Another common weakness of these works is the requirement for the mobile recharger to stop at the location of each sensor. As a result, it is impossible for recharger to move with a constant speed, leading to inefficient movement. To improve the recharging efficiency, this paper takes “recharging while moving” into consideration when constructing the recharging path. We propose a Recharging Path Construction (RPC) mechanism, which enables the mobile recharger to recharge all sensors using a constant speed, aiming to minimize the length of recharging path and improve the recharging efficiency while achieving the requirement of perpetual network lifetime of a given WSN. Performance studies reveal that the proposed RPC outperforms existing proposals in terms of path length and energy utilization index, as well as visiting cycle. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 3968 KiB

Open AccessArticle

Finite Element Analysis of Single Cell Stiffness Measurements Using PZT-Integrated Buckling Nanoneedles

by Maryam Alsadat Rad, Auwal Shehu Tijjani

, Mohd Ridzuan Ahmad^* and Shehu Muhammad Auwal

Department of Control and Mechatronics Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia

Sensors 2017, 17(1), 14; https://doi.org/10.3390/s17010014 - 23 Dec 2016

Cited by 1 | Viewed by 5483

Abstract

This paper proposes a new technique for real-time single cell stiffness measurement using lead zirconate titanate (PZT)-integrated buckling nanoneedles. The PZT and the buckling part of the nanoneedle have been modelled and validated using the ABAQUS software. The two parts are integrated together [...] Read more.

This paper proposes a new technique for real-time single cell stiffness measurement using lead zirconate titanate (PZT)-integrated buckling nanoneedles. The PZT and the buckling part of the nanoneedle have been modelled and validated using the ABAQUS software. The two parts are integrated together to function as a single unit. After calibration, the stiffness, Young’s modulus, Poisson’s ratio and sensitivity of the PZT-integrated buckling nanoneedle have been determined to be 0.7100 N·m⁻¹, 123.4700 GPa, 0.3000 and 0.0693 V·m·N⁻¹, respectively. Three Saccharomyces cerevisiae cells have been modelled and validated based on compression tests. The average global stiffness and Young’s modulus of the cells are determined to be 10.8867 ± 0.0094 N·m⁻¹ and 110.7033 ± 0.0081 MPa, respectively. The nanoneedle and the cell have been assembled to measure the local stiffness of the single Saccharomyces cerevisiae cells The local stiffness, Young’s modulus and PZT output voltage of the three different size Saccharomyces cerevisiae have been determined at different environmental conditions. We investigated that, at low temperature the stiffness value is low to adapt to the change in the environmental condition. As a result, Saccharomyces cerevisiae becomes vulnerable to viral and bacterial attacks. Therefore, the proposed technique will serve as a quick and accurate process to diagnose diseases at early stage in a cell for effective treatment. Full article

(This article belongs to the Section Biosensors)

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12 pages, 6929 KiB

Open AccessArticle

High Performance CMOS Light Detector with Dark Current Suppression in Variable-Temperature Systems

by Wen-Sheng Lin, Guo-Ming Sung^* and Jyun-Long Lin

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

Sensors 2017, 17(1), 15; https://doi.org/10.3390/s17010015 - 23 Dec 2016

Cited by 6 | Viewed by 6976

Abstract

This paper presents a dark current suppression technique for a light detector in a variable-temperature system. The light detector architecture comprises a photodiode for sensing the ambient light, a dark current diode for conducting dark current suppression, and a current subtractor that is [...] Read more.

This paper presents a dark current suppression technique for a light detector in a variable-temperature system. The light detector architecture comprises a photodiode for sensing the ambient light, a dark current diode for conducting dark current suppression, and a current subtractor that is embedded in the current amplifier with enhanced dark current cancellation. The measured dark current of the proposed light detector is lower than that of the epichlorohydrin photoresistor or cadmium sulphide photoresistor. This is advantageous in variable-temperature systems, especially for those with many infrared light-emitting diodes. Experimental results indicate that the maximum dark current of the proposed current amplifier is approximately 135 nA at 125 °C, a near zero dark current is achieved at temperatures lower than 50 °C, and dark current and temperature exhibit an exponential relation at temperatures higher than 50 °C. The dark current of the proposed light detector is lower than 9.23 nA and the linearity is approximately 1.15 μA/lux at an external resistance R_SS = 10 kΩ and environmental temperatures from 25 °C to 85 °C. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 5017 KiB

Open AccessArticle

A Circuit-Based Neural Network with Hybrid Learning of Backpropagation and Random Weight Change Algorithms

by Changju Yang¹, Hyongsuk Kim^1,*

, Shyam Prasad Adhikari¹ and Leon O. Chua²

¹ Division of Electronics Engineering, Intelligent Robot Research Center, Chonbuk National University, Jeonbuk 54896, Korea

² Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720, USA

Sensors 2017, 17(1), 16; https://doi.org/10.3390/s17010016 - 23 Dec 2016

Cited by 19 | Viewed by 10136

Abstract

A hybrid learning method of a software-based backpropagation learning and a hardware-based RWC learning is proposed for the development of circuit-based neural networks. The backpropagation is known as one of the most efficient learning algorithms. A weak point is that its hardware implementation [...] Read more.

A hybrid learning method of a software-based backpropagation learning and a hardware-based RWC learning is proposed for the development of circuit-based neural networks. The backpropagation is known as one of the most efficient learning algorithms. A weak point is that its hardware implementation is extremely difficult. The RWC algorithm, which is very easy to implement with respect to its hardware circuits, takes too many iterations for learning. The proposed learning algorithm is a hybrid one of these two. The main learning is performed with a software version of the BP algorithm, firstly, and then, learned weights are transplanted on a hardware version of a neural circuit. At the time of the weight transplantation, a significant amount of output error would occur due to the characteristic difference between the software and the hardware. In the proposed method, such error is reduced via a complementary learning of the RWC algorithm, which is implemented in a simple hardware. The usefulness of the proposed hybrid learning system is verified via simulations upon several classical learning problems. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 6230 KiB

Open AccessArticle

Nanostructured Tip-Shaped Biosensors: Application of Six Sigma Approach for Enhanced Manufacturing

by Seong-Joong Kahng¹, Jong-Hoon Kim^2,*

and Jae-Hyun Chung¹

¹ Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA

² School of Engineering and Computer Science, Washington State University, Vancouver, WA 98686, USA

Sensors 2017, 17(1), 17; https://doi.org/10.3390/s17010017 - 23 Dec 2016

Cited by 18 | Viewed by 6631

Abstract

Nanostructured tip-shaped biosensors have drawn attention for biomolecule detection as they are promising for highly sensitive and specific detection of a target analyte. Using a nanostructured tip, the sensitivity is increased to identify individual molecules because of the high aspect ratio structure. Various [...] Read more.

Nanostructured tip-shaped biosensors have drawn attention for biomolecule detection as they are promising for highly sensitive and specific detection of a target analyte. Using a nanostructured tip, the sensitivity is increased to identify individual molecules because of the high aspect ratio structure. Various detection methods, such as electrochemistry, fluorescence microcopy, and Raman spectroscopy, have been attempted to enhance the sensitivity and the specificity. Due to the confined path of electrons, electrochemical measurement using a nanotip enables the detection of single molecules. When an electric field is combined with capillary action and fluid flow, target molecules can be effectively concentrated onto a nanotip surface for detection. To enhance the concentration efficacy, a dendritic nanotip rather than a single tip could be used to detect target analytes, such as nanoparticles, cells, and DNA. However, reproducible fabrication with relation to specific detection remains a challenge due to the instability of a manufacturing method, resulting in inconsistent shape. In this paper, nanostructured biosensors are reviewed with our experimental results using dendritic nanotips for sequence specific detection of DNA. By the aid of the Six Sigma approach, the fabrication yield of dendritic nanotips increases from 20.0% to 86.6%. Using the nanotips, DNA is concentrated and detected in a sequence specific way with the detection limit equivalent to 1000 CFU/mL. The pros and cons of a nanotip biosensor are evaluated in conjunction with future prospects. Full article

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

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20 pages, 12514 KiB

Open AccessArticle

A Machine Learning Approach to Pedestrian Detection for Autonomous Vehicles Using High-Definition 3D Range Data

by Pedro J. Navarro^*,†

, Carlos Fernández^†, Raúl Borraz^† and Diego Alonso^†

¹ División de Sistemas en Ingeniería Electrónica (DSIE), Universidad Politécnica de Cartagena, Campus Muralla del Mar, s/n, Cartagena 30202, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 18; https://doi.org/10.3390/s17010018 - 23 Dec 2016

Cited by 102 | Viewed by 19895

Abstract

This article describes an automated sensor-based system to detect pedestrians in an autonomous vehicle application. Although the vehicle is equipped with a broad set of sensors, the article focuses on the processing of the information generated by a Velodyne HDL-64E LIDAR sensor. The [...] Read more.

This article describes an automated sensor-based system to detect pedestrians in an autonomous vehicle application. Although the vehicle is equipped with a broad set of sensors, the article focuses on the processing of the information generated by a Velodyne HDL-64E LIDAR sensor. The cloud of points generated by the sensor (more than 1 million points per revolution) is processed to detect pedestrians, by selecting cubic shapes and applying machine vision and machine learning algorithms to the XY, XZ, and YZ projections of the points contained in the cube. The work relates an exhaustive analysis of the performance of three different machine learning algorithms: k-Nearest Neighbours (kNN), Naïve Bayes classifier (NBC), and Support Vector Machine (SVM). These algorithms have been trained with 1931 samples. The final performance of the method, measured a real traffic scenery, which contained 16 pedestrians and 469 samples of non-pedestrians, shows sensitivity (81.2%), accuracy (96.2%) and specificity (96.8%). Full article

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

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31 pages, 1047 KiB

Open AccessArticle

A Formal Methodology to Design and Deploy Dependable Wireless Sensor Networks

by Alessandro Testa¹, Marcello Cinque², Antonio Coronato^3,*

and Juan Carlos Augusto⁴

¹ Ministero dell’Economia e delle Finanze, Rome 00187, Italy

² Dipartimento di Ingegneria Elettrica e delle Tecnologie dell’Informazione, University of Naples “Federico II”, Naples 80125, Italy

³ CNR-ICAR, Naples 80131, Italy

⁴ Department of Computer Science and R.G. on Development of Intelligent Environments, Middlesex University of London, London NW4 2SH, UK

Sensors 2017, 17(1), 19; https://doi.org/10.3390/s17010019 - 23 Dec 2016

Cited by 4 | Viewed by 6097

Abstract

Wireless Sensor Networks (WSNs) are being increasingly adopted in critical applications, where verifying the correct operation of sensor nodes is a major concern. Undesired events may undermine the mission of the WSNs. Hence, their effects need to be properly assessed before deployment, to [...] Read more.

Wireless Sensor Networks (WSNs) are being increasingly adopted in critical applications, where verifying the correct operation of sensor nodes is a major concern. Undesired events may undermine the mission of the WSNs. Hence, their effects need to be properly assessed before deployment, to obtain a good level of expected performance; and during the operation, in order to avoid dangerous unexpected results. In this paper, we propose a methodology that aims at assessing and improving the dependability level of WSNs by means of an event-based formal verification technique. The methodology includes a process to guide designers towards the realization of a dependable WSN and a tool (“ADVISES”) to simplify its adoption. The tool is applicable to homogeneous WSNs with static routing topologies. It allows the automatic generation of formal specifications used to check correctness properties and evaluate dependability metrics at design time and at runtime for WSNs where an acceptable percentage of faults can be defined. During the runtime, we can check the behavior of the WSN accordingly to the results obtained at design time and we can detect sudden and unexpected failures, in order to trigger recovery procedures. The effectiveness of the methodology is shown in the context of two case studies, as proof-of-concept, aiming to illustrate how the tool is helpful to drive design choices and to check the correctness properties of the WSN at runtime. Although the method scales up to very large WSNs, the applicability of the methodology may be compromised by the state space explosion of the reasoning model, which must be faced by partitioning large topologies into sub-topologies. Full article

(This article belongs to the Section Sensor Networks)

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11 pages, 5697 KiB

Open AccessArticle

Simultaneous Moisture Content and Mass Flow Measurements in Wood Chip Flows Using Coupled Dielectric and Impact Sensors

by Pengmin Pan^1,*

, Timothy McDonald¹, John Fulton², Brian Via³ and John Hung⁴

¹ Biosystems Engineering Department, Auburn University, 200 Corley Building, Auburn University, Auburn, AL 36849, USA

² Department of Food, Agricultural and Biological Engineering, Ohio State University, 590 Woody Hayes Drive, Columbus, OH 43210-1057, USA

³ School of Forestry and Wildlife Sciences, Auburn University, 602 Duncan Drive, Auburn University, Auburn, AL 36849, USA

⁴ Electrical & Computer Engineering Department, Auburn University, 200 Broun Hall, Auburn University, Auburn, AL 36849, USA

Sensors 2017, 17(1), 20; https://doi.org/10.3390/s17010020 - 23 Dec 2016

Cited by 7 | Viewed by 6153

Abstract

An 8-electrode capacitance tomography (ECT) sensor was built and used to measure moisture content (MC) and mass flow of pine chip flows. The device was capable of directly measuring total water quantity in a sample but was sensitive to both dry matter and [...] Read more.

An 8-electrode capacitance tomography (ECT) sensor was built and used to measure moisture content (MC) and mass flow of pine chip flows. The device was capable of directly measuring total water quantity in a sample but was sensitive to both dry matter and moisture, and therefore required a second measurement of mass flow to calculate MC. Two means of calculating the mass flow were used: the first being an impact sensor to measure total mass flow, and the second a volumetric approach based on measuring total area occupied by wood in images generated using the capacitance sensor’s tomographic mode. Tests were made on 109 groups of wood chips ranging in moisture content from 14% to 120% (dry basis) and wet weight of 280 to 1100 g. Sixty groups were randomly selected as a calibration set, and the remaining were used for validation of the sensor’s performance. For the combined capacitance/force transducer system, root mean square errors of prediction (RMSEP) for wet mass flow and moisture content were 13.42% and 16.61%, respectively. RMSEP using the combined volumetric mass flow/capacitance sensor for dry mass flow and moisture content were 22.89% and 24.16%, respectively. Either of the approaches was concluded to be feasible for prediction of moisture content in pine chip flows, but combining the impact and capacitance sensors was easier to implement. In situations where flows could not be impeded, however, the tomographic approach would likely be more useful. Full article

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

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17 pages, 2584 KiB

Open AccessArticle

A Novel Controller Design for the Next Generation Space Electrostatic Accelerometer Based on Disturbance Observation and Rejection

by Hongyin Li^1,2, Yanzheng Bai¹, Ming Hu³, Yingxin Luo⁴ and Zebing Zhou^1,*

¹ MOE Key Laboratory of Fundamental Quantities Measurement, School of Physics, Huazhong University of Science and Technology (HUST), Wuhan 430074, China

² School of Automation, Huazhong University of Science and Technology (HUST), Wuhan 430074, China

³ Institute of Geodesy and Geophysics, Chinese Academy of Science, Wuhan 430077, China

⁴ Tianqin Research Center for Gravitational Physics, School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082, China

Sensors 2017, 17(1), 21; https://doi.org/10.3390/s17010021 - 23 Dec 2016

Cited by 17 | Viewed by 7516

Abstract

The state-of-the-art accelerometer technology has been widely applied in space missions. The performance of the next generation accelerometer in future geodesic satellites is pushed to

8 \times 10^{- 13} m / s^{2} / H z^{1 / 2}

, which is [...] Read more.

The state-of-the-art accelerometer technology has been widely applied in space missions. The performance of the next generation accelerometer in future geodesic satellites is pushed to

8 \times 10^{- 13} m / s^{2} / H z^{1 / 2}

, which is close to the hardware fundamental limit. According to the instrument noise budget, the geodesic test mass must be kept in the center of the accelerometer within the bounds of 56

pm / {Hz}^{1 / 2}

by the feedback controller. The unprecedented control requirements and necessity for the integration of calibration functions calls for a new type of control scheme with more flexibility and robustness. A novel digital controller design for the next generation electrostatic accelerometers based on disturbance observation and rejection with the well-studied Embedded Model Control (EMC) methodology is presented. The parameters are optimized automatically using a non-smooth optimization toolbox and setting a weighted H-infinity norm as the target. The precise frequency performance requirement of the accelerometer is well met during the batch auto-tuning, and a series of controllers for multiple working modes is generated. Simulation results show that the novel controller could obtain not only better disturbance rejection performance than the traditional Proportional Integral Derivative (PID) controllers, but also new instrument functions, including: easier tuning procedure, separation of measurement and control bandwidth and smooth control parameter switching. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 4551 KiB

Open AccessArticle

Robust Functionalization of Large Microelectrode Arrays by Using Pulsed Potentiostatic Deposition

by Joerg Rothe^1,*, Olivier Frey¹, Rajtarun Madangopal^2,3, Jenna Rickus² and Andreas Hierlemann¹

¹ ETH Zurich, Department of Biosystems Science and Engineering, Bio Engineering Laboratory, Mattenstrasse 26, CH-4058 Basel, Switzerland

² Agricultural and Biological Engineering, Biomedical Engineering, Physiological Sensing Facility at the Bindley Bioscience Center and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA

³ Intramural Research Program of the National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA

Sensors 2017, 17(1), 22; https://doi.org/10.3390/s17010022 - 23 Dec 2016

Cited by 9 | Viewed by 6894

Abstract

Surface modification of microelectrodes is a central step in the development of microsensors and microsensor arrays. Here, we present an electrodeposition scheme based on voltage pulses. Key features of this method are uniformity in the deposited electrode coatings, flexibility in the overall deposition [...] Read more.

Surface modification of microelectrodes is a central step in the development of microsensors and microsensor arrays. Here, we present an electrodeposition scheme based on voltage pulses. Key features of this method are uniformity in the deposited electrode coatings, flexibility in the overall deposition area, i.e., the sizes and number of the electrodes to be coated, and precise control of the surface texture. Deposition and characterization of four different materials are demonstrated, including layers of high-surface-area platinum, gold, conducting polymer poly(ethylenedioxythiophene), also known as PEDOT, and the non-conducting polymer poly(phenylenediamine), also known as PPD. The depositions were conducted using a fully integrated complementary metal-oxide-semiconductor (CMOS) chip with an array of 1024 microelectrodes. The pulsed potentiostatic deposition scheme is particularly suitable for functionalization of individual electrodes or electrode subsets of large integrated microelectrode arrays: the required deposition waveforms are readily available in an integrated system, the same deposition parameters can be used to functionalize the surface of either single electrodes or large arrays of thousands of electrodes, and the deposition method proved to be robust and reproducible for all materials tested. Full article

(This article belongs to the Special Issue Integrated Sensor Arrays and Array Signal Processing)

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12 pages, 7555 KiB

Open AccessArticle

Experimental Investigations of a Precision Sensor for an Automatic Weapons Stabilizer System

by Igor Korobiichuk

Industrial Research Institute for Automation and Measurements PIAP, Jerozolimskie 202, 02-486 Warsaw, Poland

Sensors 2017, 17(1), 23; https://doi.org/10.3390/s17010023 - 24 Dec 2016

Cited by 5 | Viewed by 4596

Abstract

This paper presents the results of experimental investigations of a precision sensor for an automatic weapons stabilizer system. It also describes the experimental equipment used and the structure of the developed sensor. A weapons stabilizer is designed for automatic guidance of an armament [...] Read more.

This paper presents the results of experimental investigations of a precision sensor for an automatic weapons stabilizer system. It also describes the experimental equipment used and the structure of the developed sensor. A weapons stabilizer is designed for automatic guidance of an armament unit in the horizontal and vertical planes when firing at ground and air targets that are quickly maneuvering, and at lower speeds when firing anti-tank missiles, as well as the bypass of construction elements by the armament unit, and the automatic tracking of moving targets when interacting with a fire control system. The results of experimental investigations have shown that the error of the precision sensor developed on the basis of a piezoelectric element is 6 × 10⁻¹⁰ m/s² under quasi-static conditions, and ~10⁻⁵ m/s² for mobile use. This paper defines metrological and calibration properties of the developed sensor. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 3638 KiB

Open AccessArticle

Optical Gas Sensing of Ammonia and Amines Based on Protonated Porphyrin/TiO₂ Composite Thin Films

by Pedro Castillero¹, Javier Roales²

, Tânia Lopes-Costa², Juan R. Sánchez-Valencia¹, Angel Barranco¹, Agustín R. González-Elipe¹

and José M. Pedrosa^2,*

¹ Instituto de Ciencia de Materiales de Sevilla, CSIC–Universidad de Sevilla, Américo Vespucio 49, Sevilla 41092, Spain

² Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, Ctra. Utrera Km. 1, Sevilla 41013, Spain

Sensors 2017, 17(1), 24; https://doi.org/10.3390/s17010024 - 23 Dec 2016

Cited by 46 | Viewed by 7076

Abstract

Open porous and transparent microcolumnar structures of TiO₂ prepared by physical vapour deposition in glancing angle configuration (GLAD-PVD) have been used as host matrices for two different fluorescent cationic porphyrins, 5-(N-methyl 4-pyridyl)-10,15,20-triphenyl porphine chloride (MMPyP) and meso-tetra (N-methyl [...] Read more.

Open porous and transparent microcolumnar structures of TiO₂ prepared by physical vapour deposition in glancing angle configuration (GLAD-PVD) have been used as host matrices for two different fluorescent cationic porphyrins, 5-(N-methyl 4-pyridyl)-10,15,20-triphenyl porphine chloride (MMPyP) and meso-tetra (N-methyl 4-pyridyl) porphine tetrachloride (TMPyP). The porphyrins have been anchored by electrostatic interactions to the microcolumns by self-assembly through the dip-coating method. These porphyrin/TiO₂ composites have been used as gas sensors for ammonia and amines through previous protonation of the porphyrin with HCl followed by subsequent exposure to the basic analyte. UV–vis absorption, emission, and time-resolved spectroscopies have been used to confirm the protonation–deprotonation of the two porphyrins and to follow their spectral changes in the presence of the analytes. The monocationic porphyrin has been found to be more sensible (up to 10 times) than its tetracationic counterpart. This result has been attributed to the different anchoring arrangements of the two porphyrins to the TiO₂ surface and their different states of aggregation within the film. Finally, there was an observed decrease of the emission fluorescence intensity in consecutive cycles of exposure and recovery due to the formation of ammonium chloride inside the film. Full article

(This article belongs to the Section Chemical Sensors)

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17 pages, 1277 KiB

Open AccessArticle

Compound Event Barrier Coverage in Wireless Sensor Networks under Multi-Constraint Conditions

by Yaoming Zhuang^*

, Chengdong Wu, Yunzhou Zhang and Zixi Jia

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

Sensors 2017, 17(1), 25; https://doi.org/10.3390/s17010025 - 24 Dec 2016

Cited by 9 | Viewed by 5237

Abstract

It is important to monitor compound event by barrier coverage issues in wireless sensor networks (WSNs). Compound event barrier coverage (CEBC) is a novel coverage problem. Unlike traditional ones, the data of compound event barrier coverage comes from different types of sensors. It [...] Read more.

It is important to monitor compound event by barrier coverage issues in wireless sensor networks (WSNs). Compound event barrier coverage (CEBC) is a novel coverage problem. Unlike traditional ones, the data of compound event barrier coverage comes from different types of sensors. It will be subject to multiple constraints under complex conditions in real-world applications. The main objective of this paper is to design an efficient algorithm for complex conditions that can combine the compound event confidence. Moreover, a multiplier method based on an active-set strategy (ASMP) is proposed to optimize the multiple constraints in compound event barrier coverage. The algorithm can calculate the coverage ratio efficiently and allocate the sensor resources reasonably in compound event barrier coverage. The proposed algorithm can simplify complex problems to reduce the computational load of the network and improve the network efficiency. The simulation results demonstrate that the proposed algorithm is more effective and efficient than existing methods, especially in the allocation of sensor resources. Full article

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

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25 pages, 10148 KiB

Open AccessArticle

Change Analysis in Structural Laser Scanning Point Clouds: The Baseline Method

by Yueqian Shen^1,2,*

, Roderik Lindenbergh² and Jinhu Wang^2,3

¹ School of Earth Science and Engineering, Hohai University, No. 1, Xikang Road, Nanjing 210098, China

² Department of Geoscience and Remote Sensing, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands

³ Key Laboratory of quantitative Remote Sensing Information Technology, Academy of Opto-Electronics, Chinese Academy of Sciences, No. 9, Deng Zhuang South Road, Haidian District, Beijing 100094, China

Sensors 2017, 17(1), 26; https://doi.org/10.3390/s17010026 - 24 Dec 2016

Cited by 29 | Viewed by 6536

Abstract

A method is introduced for detecting changes from point clouds that avoids registration. For many applications, changes are detected between two scans of the same scene obtained at different times. Traditionally, these scans are aligned to a common coordinate system having the disadvantage [...] Read more.

A method is introduced for detecting changes from point clouds that avoids registration. For many applications, changes are detected between two scans of the same scene obtained at different times. Traditionally, these scans are aligned to a common coordinate system having the disadvantage that this registration step introduces additional errors. In addition, registration requires stable targets or features. To avoid these issues, we propose a change detection method based on so-called baselines. Baselines connect feature points within one scan. To analyze changes, baselines connecting corresponding points in two scans are compared. As feature points either targets or virtual points corresponding to some reconstructable feature in the scene are used. The new method is implemented on two scans sampling a masonry laboratory building before and after seismic testing, that resulted in damages in the order of several centimeters. The centres of the bricks of the laboratory building are automatically extracted to serve as virtual points. Baselines connecting virtual points and/or target points are extracted and compared with respect to a suitable structural coordinate system. Changes detected from the baseline analysis are compared to a traditional cloud to cloud change analysis demonstrating the potential of the new method for structural analysis. Full article

(This article belongs to the Section Remote Sensors)

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27 pages, 2837 KiB

Open AccessArticle

Node Redeployment Algorithm Based on Stratified Connected Tree for Underwater Sensor Networks

by Jun Liu^1,2, Peng Jiang^1,*, Feng Wu¹, Shanen Yu¹ and Chunyue Song²

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

² State Key Laboratory of Industrial Control Technology, Institute of Industrial Process Control, Zhejiang University, Hangzhou 310027, China

Sensors 2017, 17(1), 27; https://doi.org/10.3390/s17010027 - 24 Dec 2016

Cited by 2 | Viewed by 5242

Abstract

During the underwater sensor networks (UWSNs) operation, node drift with water environment causes network topology changes. Periodic node location examination and adjustment are needed to maintain good network monitoring quality as long as possible. In this paper, a node redeployment algorithm based on [...] Read more.

During the underwater sensor networks (UWSNs) operation, node drift with water environment causes network topology changes. Periodic node location examination and adjustment are needed to maintain good network monitoring quality as long as possible. In this paper, a node redeployment algorithm based on stratified connected tree for UWSNs is proposed. At every network adjustment moment, self-examination and adjustment on node locations are performed firstly. If a node is outside the monitored space, it returns to the last location recorded in its memory along straight line. Later, the network topology is stratified into a connected tree that takes the sink node as the root node by broadcasting ready information level by level, which can improve the network connectivity rate. Finally, with synthetically considering network coverage and connectivity rates, and node movement distance, the sink node performs centralized optimization on locations of leaf nodes in the stratified connected tree. Simulation results show that the proposed redeployment algorithm can not only keep the number of nodes in the monitored space as much as possible and maintain good network coverage and connectivity rates during network operation, but also reduce node movement distance during node redeployment and prolong the network lifetime. Full article

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

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31 pages, 12174 KiB

Open AccessArticle

Reverse Engineering and Security Evaluation of Commercial Tags for RFID-Based IoT Applications

by Tiago M. Fernández-Caramés^*

, Paula Fraga-Lamas

, Manuel Suárez-Albela

and Luis Castedo

Department of Electronics and Systems, Faculty of Computer Science, Universidade da Coruña, 15071 A Coruña, Spain

Sensors 2017, 17(1), 28; https://doi.org/10.3390/s17010028 - 24 Dec 2016

Cited by 72 | Viewed by 16829

Abstract

The Internet of Things (IoT) is a distributed system of physical objects that requires the seamless integration of hardware (e.g., sensors, actuators, electronics) and network communications in order to collect and exchange data. IoT smart objects need to be somehow identified to determine [...] Read more.

The Internet of Things (IoT) is a distributed system of physical objects that requires the seamless integration of hardware (e.g., sensors, actuators, electronics) and network communications in order to collect and exchange data. IoT smart objects need to be somehow identified to determine the origin of the data and to automatically detect the elements around us. One of the best positioned technologies to perform identification is RFID (Radio Frequency Identification), which in the last years has gained a lot of popularity in applications like access control, payment cards or logistics. Despite its popularity, RFID security has not been properly handled in numerous applications. To foster security in such applications, this article includes three main contributions. First, in order to establish the basics, a detailed review of the most common flaws found in RFID-based IoT systems is provided, including the latest attacks described in the literature. Second, a novel methodology that eases the detection and mitigation of such flaws is presented. Third, the latest RFID security tools are analyzed and the methodology proposed is applied through one of them (Proxmark 3) to validate it. Thus, the methodology is tested in different scenarios where tags are commonly used for identification. In such systems it was possible to clone transponders, extract information, and even emulate both tags and readers. Therefore, it is shown that the methodology proposed is useful for auditing security and reverse engineering RFID communications in IoT applications. It must be noted that, although this paper is aimed at fostering RFID communications security in IoT applications, the methodology can be applied to any RFID communications protocol. Full article

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

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17 pages, 8038 KiB

Open AccessArticle

A Visual Analytics Approach for Station-Based Air Quality Data

by Yi Du¹, Cuixia Ma², Chao Wu³, Xiaowei Xu¹, Yike Guo³, Yuanchun Zhou¹

and Jianhui Li^1,*

¹ Department of Big Data Technology and Application Development, Computer Network Information Center, Chinese Academy of Sciences, Beijing 100190, China

² Intelligence Engineering Laboratory, Institute of Software, Chinese Academy of Sciences, Beijing 100190, China

³ Department of Computing, Imperial College London, London SW7 2AZ, UK

Sensors 2017, 17(1), 30; https://doi.org/10.3390/s17010030 - 24 Dec 2016

Cited by 17 | Viewed by 7578

Abstract

With the deployment of multi-modality and large-scale sensor networks for monitoring air quality, we are now able to collect large and multi-dimensional spatio-temporal datasets. For these sensed data, we present a comprehensive visual analysis approach for air quality analysis. This approach integrates several [...] Read more.

With the deployment of multi-modality and large-scale sensor networks for monitoring air quality, we are now able to collect large and multi-dimensional spatio-temporal datasets. For these sensed data, we present a comprehensive visual analysis approach for air quality analysis. This approach integrates several visual methods, such as map-based views, calendar views, and trends views, to assist the analysis. Among those visual methods, map-based visual methods are used to display the locations of interest, and the calendar and the trends views are used to discover the linear and periodical patterns. The system also provides various interaction tools to combine the map-based visualization, trends view, calendar view and multi-dimensional view. In addition, we propose a self-adaptive calendar-based controller that can flexibly adapt the changes of data size and granularity in trends view. Such a visual analytics system would facilitate big-data analysis in real applications, especially for decision making support. Full article

(This article belongs to the Special Issue Big Data and Cloud Computing for Sensor Networks)

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14 pages, 4732 KiB

Open AccessArticle

A Canopy Density Model for Planar Orchard Target Detection Based on Ultrasonic Sensors

by Hanzhe Li¹, Changyuan Zhai^1,2,*, Paul Weckler²

, Ning Wang², Shuo Yang¹ and Bo Zhang¹

¹ College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling 712100, China

² Department of Biosystems and Agricultural Engineering, Oklahoma State University, Stillwater, OK 75078, USA

Sensors 2017, 17(1), 31; https://doi.org/10.3390/s17010031 - 24 Dec 2016

Cited by 32 | Viewed by 6397

Abstract

Orchard target-oriented variable rate spraying is an effective method to reduce pesticide drift and excessive residues. To accomplish this task, the orchard targets’ characteristic information is needed to control liquid flow rate and airflow rate. One of the most important characteristics is the [...] Read more.

Orchard target-oriented variable rate spraying is an effective method to reduce pesticide drift and excessive residues. To accomplish this task, the orchard targets’ characteristic information is needed to control liquid flow rate and airflow rate. One of the most important characteristics is the canopy density. In order to establish the canopy density model for a planar orchard target which is indispensable for canopy density calculation, a target density detection testing system was developed based on an ultrasonic sensor. A time-domain energy analysis method was employed to analyze the ultrasonic signal. Orthogonal regression central composite experiments were designed and conducted using man-made canopies of known density with three or four layers of leaves. Two model equations were obtained, of which the model for the canopies with four layers was found to be the most reliable. A verification test was conducted with different layers at the same density values and detecting distances. The test results showed that the relative errors of model density values and actual values of five, four, three and two layers of leaves were acceptable, while the maximum relative errors were 17.68%, 25.64%, 21.33% and 29.92%, respectively. It also suggested the model equation with four layers had a good applicability with different layers which increased with adjacent layers. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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13 pages, 2540 KiB

Open AccessArticle

Network Allocation Vector (NAV) Optimization for Underwater Handshaking-Based Protocols

by Junho Cho

, Ethungshan Shitiri

and Ho-Shin Cho^*

School of Electronics Engineering, Kyungpook National University, Daegu 41566, Korea

Sensors 2017, 17(1), 32; https://doi.org/10.3390/s17010032 - 24 Dec 2016

Cited by 8 | Viewed by 6966

Abstract

In this paper, we obtained the optimized network allocation vector (NAV) for underwater handshaking-based protocols, as inefficient determination of the NAV leads to unnecessarily long silent periods. We propose a scheme which determines the NAV by taking into account all possible propagation delays: [...] Read more.

In this paper, we obtained the optimized network allocation vector (NAV) for underwater handshaking-based protocols, as inefficient determination of the NAV leads to unnecessarily long silent periods. We propose a scheme which determines the NAV by taking into account all possible propagation delays: propagation delay between a source and a destination; propagation delay between a source and the neighbors; and propagation delay between a destination and the neighbors. Such an approach effectively allows the NAV to be determined precisely equal to duration of a busy channel, and the silent period can be set commensurate to that duration. This allows for improvements in the performance of handshaking-based protocols, such as the carrier sense multiple access/collision avoidance (CSMA/CA) protocol, in terms of throughput and fairness. To evaluate the performance of the proposed scheme, performance comparisons were carried out through simulations with prior NAV setting methods. The simulation results show that the proposed scheme outperforms the other schemes in terms of throughput and fairness. Full article

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

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28 pages, 9934 KiB

Open AccessArticle

Real-Time Multi-Target Localization from Unmanned Aerial Vehicles

by Xuan Wang^1,2,*, Jinghong Liu¹ and Qianfei Zhou^1,2

¹ Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China

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

Sensors 2017, 17(1), 33; https://doi.org/10.3390/s17010033 - 25 Dec 2016

Cited by 59 | Viewed by 11273

Abstract

In order to improve the reconnaissance efficiency of unmanned aerial vehicle (UAV) electro-optical stabilized imaging systems, a real-time multi-target localization scheme based on an UAV electro-optical stabilized imaging system is proposed. First, a target location model is studied. Then, the geodetic coordinates of [...] Read more.

In order to improve the reconnaissance efficiency of unmanned aerial vehicle (UAV) electro-optical stabilized imaging systems, a real-time multi-target localization scheme based on an UAV electro-optical stabilized imaging system is proposed. First, a target location model is studied. Then, the geodetic coordinates of multi-targets are calculated using the homogeneous coordinate transformation. On the basis of this, two methods which can improve the accuracy of the multi-target localization are proposed: (1) the real-time zoom lens distortion correction method; (2) a recursive least squares (RLS) filtering method based on UAV dead reckoning. The multi-target localization error model is established using Monte Carlo theory. In an actual flight, the UAV flight altitude is 1140 m. The multi-target localization results are within the range of allowable error. After we use a lens distortion correction method in a single image, the circular error probability (CEP) of the multi-target localization is reduced by 7%, and 50 targets can be located at the same time. The RLS algorithm can adaptively estimate the location data based on multiple images. Compared with multi-target localization based on a single image, CEP of the multi-target localization using RLS is reduced by 25%. The proposed method can be implemented on a small circuit board to operate in real time. This research is expected to significantly benefit small UAVs which need multi-target geo-location functions. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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9 pages, 1687 KiB

Open AccessArticle

Organophosphorous Pesticide Detection in Olive Oil by Using a Miniaturized, Easy-to-Use, and Cost-Effective Biosensor Combined with QuEChERS for Sample Clean-Up

by Fabiana Arduini^1,*, Matteo Forchielli¹, Viviana Scognamiglio², Kozitsina Alisa Nikolaevna³ and Danila Moscone¹

¹ Department of Chemical Science and Technologies, University of Rome “Tor Vergata”, Via della Ricerca Scientifica, 00133 Rome, Italy

² Institute of Crystallography (IC-CNR), Via Salaria km 29.300, 00015 Monterotondo, Italy

³ Department of Analytical Chemistry, Institute of Chemical Engineering, Ural Federal University Named After the First President of Russia B. N. Yeltsin, Mira 19, 620002 Yekaterinburg, Russian Federation

Sensors 2017, 17(1), 34; https://doi.org/10.3390/s17010034 - 24 Dec 2016

Cited by 15 | Viewed by 6660

Abstract

Herein, we report a portable electrochemical biosensor based on butyrylcholinesterase (BChE) immobilized on carbon black (CB)-modified screen-printed electrodes (SPEs) for the detection of organophosphorous pesticides in olive oil. The BChE/CB-SPE biosensor was developed to detect paraoxon in standard solutions as well as in [...] Read more.

Herein, we report a portable electrochemical biosensor based on butyrylcholinesterase (BChE) immobilized on carbon black (CB)-modified screen-printed electrodes (SPEs) for the detection of organophosphorous pesticides in olive oil. The BChE/CB-SPE biosensor was developed to detect paraoxon in standard solutions as well as in olive oil samples previously treated with the QuEChERS method to extract pesticides from the whole fatty matrix. The biosensor shows a linear concentration range of between 20 and 100 ppb for paraoxon both in standard solutions (phosphate buffer 0.05 M) and in olive oil extracts, with a detection limit of 6 ppb in olive oil extract, corresponding to 10% of inhibition. The accuracy of this biosensor in olive oil samples was assessed with olive oil spiked with paraoxon, obtaining satisfactory recovery values. Full article

(This article belongs to the Special Issue Recent Advances in Biosensors Based Screen Printed Platforms)

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8 pages, 823 KiB

Open AccessArticle

A Cu²⁺-Selective Probe Based on Phenanthro-Imidazole Derivative

by Dandan Cheng^1,†, Xingliang Liu^1,†, Hongzhi Yang¹, Tian Zhang², Aixia Han^1,* and Ling Zang^3,*

¹ Chemical Engineering College, Qinghai University, Xining 810016, China

² Qinghai Heavy Industry Vocational School, Xining 810101, China

³ Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112, USA

^† These two authors contributed equally.

Sensors 2017, 17(1), 35; https://doi.org/10.3390/s17010035 - 24 Dec 2016

Cited by 28 | Viewed by 7449

Abstract

A novel fluorescent Probe 1, based on phenanthro-imidazole has been developed as an efficient chemosensor for the trace detection of copper ions (Cu²⁺). Probe 1 demonstrated sensitive fluorescence quenching upon binding with Cu²⁺ through 1:1 stoichiometric chelation. The detection [...] Read more.

A novel fluorescent Probe 1, based on phenanthro-imidazole has been developed as an efficient chemosensor for the trace detection of copper ions (Cu²⁺). Probe 1 demonstrated sensitive fluorescence quenching upon binding with Cu²⁺ through 1:1 stoichiometric chelation. The detection limit for Cu²⁺ ions was projected through linear quenching fitting to be as low as 2.77 × 10⁻⁸ M (or 1.77 ppb). The sensing response was highly selective towards Cu²⁺ with minimal influence from other common metal ions, facilitating the practical application of Probe 1 in trace detection. Full article

(This article belongs to the Special Issue Colorimetric and Fluorescent Sensor)

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22 pages, 1518 KiB

Open AccessArticle

An Indoor Positioning System Based on Wearables for Ambient-Assisted Living

by Óscar Belmonte-Fernández^1,*

, Adrian Puertas-Cabedo², Joaquín Torres-Sospedra¹

, Raúl Montoliu-Colás¹ and Sergi Trilles-Oliver¹

¹ Institute of New Imaging Technologies (INIT), Jaume I University, Av. Vicente Sos Baynat s/n, 12071 Castelló de la Plana, Spain

² Soluciones Cuatroochenta S.L., Av. Vicente Sos Baynat s/n, Espaitec2 Building, 12071 Castelló de la Plana, Spain

Sensors 2017, 17(1), 36; https://doi.org/10.3390/s17010036 - 25 Dec 2016

Cited by 65 | Viewed by 9626

Abstract

The urban population is growing at such a rate that by 2050 it is estimated that 84% of the world’s population will live in cities, with flats being the most common living place. Moreover, WiFi technology is present in most developed country urban [...] Read more.

The urban population is growing at such a rate that by 2050 it is estimated that 84% of the world’s population will live in cities, with flats being the most common living place. Moreover, WiFi technology is present in most developed country urban areas, with a quick growth in developing countries. New Ambient-Assisted Living applications will be developed in the near future having user positioning as ground technology: elderly tele-care, energy consumption, security and the like are strongly based on indoor positioning information. We present an Indoor Positioning System for wearable devices based on WiFi fingerprinting. Smart-watch wearable devices are used to acquire the WiFi strength signals of the surrounding Wireless Access Points used to build an ensemble of Machine Learning classification algorithms. Once built, the ensemble algorithm is used to locate a user based on the WiFi strength signals provided by the wearable device. Experimental results for five different urban flats are reported, showing that the system is robust and reliable enough for locating a user at room level into his/her home. Another interesting characteristic of the presented system is that it does not require deployment of any infrastructure, and it is unobtrusive, the only device required for it to work is a smart-watch. Full article

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10 pages, 2940 KiB

Open AccessArticle

Enhancement of Fluorescence-Based Sandwich Immunoassay Using Multilayered Microplates Modified with Plasma-Polymerized Films

by Kazuyoshi Yano^* and Akira Iwasaki

School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan

Sensors 2017, 17(1), 37; https://doi.org/10.3390/s17010037 - 25 Dec 2016

Cited by 7 | Viewed by 5515

Abstract

A functional modification of the surface of a 96-well microplate coupled with a thin layer deposition technique is demonstrated for enhanced fluorescence-based sandwich immunoassays. The plasma polymerization technique enabling the deposition of organic thin films was employed for the modification of the well [...] Read more.

A functional modification of the surface of a 96-well microplate coupled with a thin layer deposition technique is demonstrated for enhanced fluorescence-based sandwich immunoassays. The plasma polymerization technique enabling the deposition of organic thin films was employed for the modification of the well surface of a microplate. A silver layer and a plasma-polymerized film were consecutively deposited on the microplate as a metal mirror and the optical interference layer, respectively. When Cy3-labeled antibody was applied to the wells of the resulting multilayered microplate without any immobilization step, greatly enhanced fluorescence was observed compared with that obtained with the unmodified one. The same effect could be also exhibited for an immunoassay targeting antigen directly adsorbed on the multilayered microplate. Furthermore, a sandwich immunoassay for the detection of interleukin 2 (IL-2) was performed with the multilayered microplates, resulting in specific and 88-fold–enhanced fluorescence detection. Full article

(This article belongs to the Special Issue Colorimetric and Fluorescent Sensor)

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22 pages, 6587 KiB

Open AccessArticle

Fiber-Optic Fabry-Pérot Interferometers for Axial Force Sensing on the Tip of a Needle

by Steven Beekmans^1,*, Thomas Lembrechts², John Van den Dobbelsteen² and Dennis Van Gerwen²

¹ Department of Physics and Astronomy and LaserLab Amsterdam, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, The Netherlands

² Department of Biomechanical Engineering, Delft University of Technology, Delft 2628 CD, The Netherlands

Sensors 2017, 17(1), 38; https://doi.org/10.3390/s17010038 - 26 Dec 2016

Cited by 17 | Viewed by 6705

Abstract

A range of complex percutaneous procedures, such as biopsy or regional anesthesia, rely heavily on accurate needle insertion. Small variations in the mechanical properties of the pierced tissue can however cause deviations from the projected needle path and can thus result in inaccurate [...] Read more.

A range of complex percutaneous procedures, such as biopsy or regional anesthesia, rely heavily on accurate needle insertion. Small variations in the mechanical properties of the pierced tissue can however cause deviations from the projected needle path and can thus result in inaccurate placement of the needle. Navigation of a rigid needle towards the target tissue is traditionally based on the surgeons capacity to interpret small variations in the needle insertion force. A more accurate measurement of these small force variations enables improvement in needle targeting, can potentially aid in enhancing force feedback in robotic needle placement and can provide valuable information on tissue-tool interaction. In this study we investigated several concepts for the design of a force sensor based on a fiber-optic Fabry-Pérot interferometer to measure needle-tissue interaction forces on the tip of a 18 G needle, where special attention was given to concepts for a sensor with (1), an intrinsic low cross-sensitivity to temperature and (2), elementary design and fabrication. Three concepts, using either a quartz capillary, an Invar capillary or a thin polyimide film as the force sensitive element were prototyped and subjected to both static and dynamic testing. The force transducer based on a quartz capillary presented the lowest cross-sensitivity to temperature (

12 m N /^{\circ}

C) and good accuracy (maximum measurement error of 65

m N

/10

N

) in a measurement of static forces. However, limited strength of the sensor is expected to prevent usage of the quartz capillary in small diameter needles. The concepts for a sensor based on an Invar capillary or a thin polyimide film proved a higher cross-sensitivity to temperature (

50 m N /^{\circ}

C and

220 m N /^{\circ}

C, respectively) and higher maximum measurement error (350

m N

/10

N

, 800

m N

/10

N

), comparable to those of FBG-based sensors reported in literature, but are likely to be more suitable for integration in very small biopsy needles. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 1423 KiB

Open AccessArticle

Threshold-Based Random Charging Scheme for Decentralized PEV Charging Operation in a Smart Grid

by Ojin Kwon, Pilkee Kim and Yong-Jin Yoon^*

School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore

Sensors 2017, 17(1), 39; https://doi.org/10.3390/s17010039 - 26 Dec 2016

Cited by 1 | Viewed by 4924

Abstract

Smart grids have been introduced to replace conventional power distribution systems without real time monitoring for accommodating the future market penetration of plug-in electric vehicles (PEVs). When a large number of PEVs require simultaneous battery charging, charging coordination techniques have become one of [...] Read more.

Smart grids have been introduced to replace conventional power distribution systems without real time monitoring for accommodating the future market penetration of plug-in electric vehicles (PEVs). When a large number of PEVs require simultaneous battery charging, charging coordination techniques have become one of the most critical factors to optimize the PEV charging performance and the conventional distribution system. In this case, considerable computational complexity of a central controller and exchange of real time information among PEVs may occur. To alleviate these problems, a novel threshold-based random charging (TBRC) operation for a decentralized charging system is proposed. Using PEV charging thresholds and random access rates, the PEVs themselves can participate in the charging requests. As PEVs with a high battery state do not transmit the charging requests to the central controller, the complexity of the central controller decreases due to the reduction of the charging requests. In addition, both the charging threshold and the random access rate are statistically calculated based on the average of supply power of the PEV charging system that do not require a real time update. By using the proposed TBRC with a tolerable PEV charging degradation, a 51% reduction of the PEV charging requests is achieved. Full article

(This article belongs to the Special Issue Vehicular Sensor Networks: Technical Challenges, Supports, and Application Experiences)

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19 pages, 6427 KiB

Open AccessArticle

A Measurement Method for Large Parts Combining with Feature Compression Extraction and Directed Edge-Point Criterion

by Wei Liu^*, Yang Zhang

, Fan Yang, Peng Gao, Zhiguang Lan, Zhenyuan Jia and Hang Gao

Key Laboratory for Precision and Non-Traditional Machining Technology of the Ministry of Education, Dalian University of Technology, No. 2 LingGong Road, Dalian 116024, China

Sensors 2017, 17(1), 40; https://doi.org/10.3390/s17010040 - 26 Dec 2016

Cited by 6 | Viewed by 5170

Abstract

High-accuracy surface measurement of large aviation parts is a significant guarantee of aircraft assembly with high quality. The result of boundary measurement is a significant parameter for aviation-part measurement. This paper proposes a measurement method for accurately measuring the surface and boundary of [...] Read more.

High-accuracy surface measurement of large aviation parts is a significant guarantee of aircraft assembly with high quality. The result of boundary measurement is a significant parameter for aviation-part measurement. This paper proposes a measurement method for accurately measuring the surface and boundary of aviation part with feature compression extraction and directed edge-point criterion. To improve the measurement accuracy of both the surface and boundary of large parts, extraction method of global boundary and feature analysis of local stripe are combined. The center feature of laser stripe is obtained with high accuracy and less calculation using a sub-pixel centroid extraction method based on compress processing. This method consists of a compressing process of images and judgment criterion of laser stripe centers. An edge-point extraction method based on directed arc-length criterion is proposed to obtain accurate boundary. Finally, a high-precision reconstruction of aerospace part is achieved. Experiments are performed both in a laboratory and an industrial field. The physical measurements validate that the mean distance deviation of the proposed method is 0.47 mm. The results of the field experimentation show the validity of the proposed method. Full article

(This article belongs to the Special Issue Applications of Advanced Materials on Microelectronic and Optical Sensors)

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9 pages, 3110 KiB

Open AccessArticle

Multi-User Identification-Based Eye-Tracking Algorithm Using Position Estimation

by Suk-Ju Kang

Department of Electronic Engineering, Sogang University, Seoul 04107, Korea

Sensors 2017, 17(1), 41; https://doi.org/10.3390/s17010041 - 27 Dec 2016

Cited by 8 | Viewed by 7120

Abstract

This paper proposes a new multi-user eye-tracking algorithm using position estimation. Conventional eye-tracking algorithms are typically suitable only for a single user, and thereby cannot be used for a multi-user system. Even though they can be used to track the eyes of multiple [...] Read more.

This paper proposes a new multi-user eye-tracking algorithm using position estimation. Conventional eye-tracking algorithms are typically suitable only for a single user, and thereby cannot be used for a multi-user system. Even though they can be used to track the eyes of multiple users, their detection accuracy is low and they cannot identify multiple users individually. The proposed algorithm solves these problems and enhances the detection accuracy. Specifically, the proposed algorithm adopts a classifier to detect faces for the red, green, and blue (RGB) and depth images. Then, it calculates features based on the histogram of the oriented gradient for the detected facial region to identify multiple users, and selects the template that best matches the users from a pre-determined face database. Finally, the proposed algorithm extracts the final eye positions based on anatomical proportions. Simulation results show that the proposed algorithm improved the average F₁ score by up to 0.490, compared with benchmark algorithms. Full article

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

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14 pages, 8295 KiB

Open AccessArticle

Feasibility Test of a Liquid Film Thickness Sensor on a Flexible Printed Circuit Board Using a Three-Electrode Conductance Method

by Kyu Byung Lee^1,2, Jong Rok Kim³, Goon Cherl Park¹ and Hyoung Kyu Cho^1,*

¹ Department of Nuclear Engineering, Seoul National University, Seoul 08826, Korea

² Department of Nuclear Safety, Korea Institute of Nuclear Safety, Daejeon 34142, Korea

³ Thermal Hydraulics Safety Research Division, Korea Atomic Energy Research Institute, Daejeon 34057, Korea

Sensors 2017, 17(1), 42; https://doi.org/10.3390/s17010042 - 27 Dec 2016

Cited by 24 | Viewed by 7768

Abstract

Liquid film thickness measurements under temperature-varying conditions in a two-phase flow are of great importance to refining our understanding of two-phase flows. In order to overcome the limitations of the conventional electrical means of measuring the thickness of a liquid film, this study [...] Read more.

Liquid film thickness measurements under temperature-varying conditions in a two-phase flow are of great importance to refining our understanding of two-phase flows. In order to overcome the limitations of the conventional electrical means of measuring the thickness of a liquid film, this study proposes a three-electrode conductance method, with the device fabricated on a flexible printed circuit board (FPCB). The three-electrode conductance method offers the advantage of applicability under conditions with varying temperatures in principle, while the FPCB has the advantage of usability on curved surfaces and in relatively high-temperature conditions in comparison with sensors based on a printed circuit board (PCB). Two types of prototype sensors were fabricated on an FPCB and the feasibility of both was confirmed in a calibration test conducted at different temperatures. With the calibrated sensor, liquid film thickness measurements were conducted via a falling liquid film flow experiment, and the working performance was tested. Full article

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

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16 pages, 5617 KiB

Open AccessArticle

Statistical Modeling of Indirect Paths for UWB Sensors in an Indoor Environment

by Moona Lee¹ and Joon-Yong Lee^2,*

¹ Siemens Healthcare Ltd., Pohang-si 37668, Korea

² School of Computer Science & Electrical Engineering, Handong Global University, Pohang-si 37554, Korea

Sensors 2017, 17(1), 43; https://doi.org/10.3390/s17010043 - 27 Dec 2016

Cited by 5 | Viewed by 4471

Abstract

In this paper, we present a statistical model of an indirect path generated in an ultra-wideband (UWB) human tracking scenario. When performing moving target detection, an indirect path signal can generate ghost targets that may cause a false alarm. For this purpose, we [...] Read more.

In this paper, we present a statistical model of an indirect path generated in an ultra-wideband (UWB) human tracking scenario. When performing moving target detection, an indirect path signal can generate ghost targets that may cause a false alarm. For this purpose, we performed radar measurements in an indoor environment and established a statistical model of an indirect path based on the measurement data. The proposed model takes the form of a modified Saleh–Valenzuela model, which is used in a UWB channel model. An application example of the proposed model for mitigating false alarms is also presented. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 2426 KiB

Open AccessArticle

TPLE: A Reliable Data Delivery Scheme for On-Road WSN Traffic Monitoring

by Rui Wang^1,2,*, Fei Chang¹ and Suli Ren¹

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

² Beijing Key Laboratory of Knowledge Engineering for Materials Science, Beijing 100083, China

Sensors 2017, 17(1), 44; https://doi.org/10.3390/s17010044 - 27 Dec 2016

Cited by 2 | Viewed by 5001

Abstract

In an on-road environment, motor-engines severely disturb the wireless link of a sensor node, leading to high package loss rate, high delivery delay, and poor radio communication quality. The existing data delivery mechanisms, such as the ACK-based retransmission mechanism and window-based link quality [...] Read more.

In an on-road environment, motor-engines severely disturb the wireless link of a sensor node, leading to high package loss rate, high delivery delay, and poor radio communication quality. The existing data delivery mechanisms, such as the ACK-based retransmission mechanism and window-based link quality estimation mechanism, could not handle these challenges well. To solve this challenge, we propose a Target-Prediction-based Link quality Estimation scheme (TPLE) to realize high quality data delivery in an on-road environment. To perform on-road link quality estimation, TPLE dynamically calculates the track of a nearby vehicle target and estimates target impact on wireless link. Based on the local estimation of link quality, TPLE schedules radio communication tasks effectively. Simulations indicate that our proposed TPLE scheme produces a 94% data delivery rate, its average retransmission number is around 0.8. Our conducted on-road data delivery experiments also indicated a similar result as the computer simulation. Full article

(This article belongs to the Special Issue Vehicular Sensor Networks: Technical Challenges, Supports, and Application Experiences)

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14 pages, 2131 KiB

Open AccessArticle

DEP-On-Go for Simultaneous Sensing of Multiple Heavy Metals Pollutants in Environmental Samples

by Madhu Biyani^1,2, Radhika Biyani², Tomoko Tsuchihashi¹, Yuzuru Takamura³, Hiromi Ushijima¹, Eiichi Tamiya^1,4 and Manish Biyani^2,3,*

¹ BioDevice Technology Ltd., 2-13 Asahidai, Nomi City, Ishikawa 923-1211, Japan

² Biyani BioSolutions Pvt. Ltd., Biyani Research Group, R-4, Sector 3, Vidhyadhar Nagar, Jaipur 302023, India

³ Department of Bioscience and Biotechnology, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi City, Ishikawa 923-1292, Japan

⁴ Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

Sensors 2017, 17(1), 45; https://doi.org/10.3390/s17010045 - 27 Dec 2016

Cited by 35 | Viewed by 10878

Abstract

We describe a simple and affordable “Disposable electrode printed (DEP)-On-Go” sensing platform for the rapid on-site monitoring of trace heavy metal pollutants in environmental samples for early warning by developing a mobile electrochemical device composed of palm-sized potentiostat and disposable unmodified screen-printed electrode [...] Read more.

We describe a simple and affordable “Disposable electrode printed (DEP)-On-Go” sensing platform for the rapid on-site monitoring of trace heavy metal pollutants in environmental samples for early warning by developing a mobile electrochemical device composed of palm-sized potentiostat and disposable unmodified screen-printed electrode chips. We present the analytical performance of our device for the sensitive detection of major heavy metal ions, namely, mercury, cadmium, lead, arsenic, zinc, and copper with detection limits of 1.5, 2.6, 4.0, 5.0, 14.4, and, 15.5 μg·L⁻¹, respectively. Importantly, the utility of this device is extended to detect multiple heavy metals simultaneously with well-defined voltammograms and similar sensitivity. Finally, “DEP-On-Go” was successfully applied to detect heavy metals in real environmental samples from groundwater, tap water, house dust, soil, and industry-processed rice and noodle foods. We evaluated the efficiency of this system with a linear correlation through inductively coupled plasma mass spectrometry, and the results suggested that this system can be reliable for on-site screening purposes. On-field applications using real samples of groundwater for drinking in the northern parts of India support the easy-to-detect, low-cost (<1 USD), rapid (within 5 min), and reliable detection limit (ppb levels) performance of our device for the on-site detection and monitoring of multiple heavy metals in resource-limited settings. Full article

(This article belongs to the Special Issue Point-of-Care Biosensors)

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25 pages, 17523 KiB

Open AccessArticle

Sensing Technologies for Autism Spectrum Disorder Screening and Intervention

by John-John Cabibihan^1,*,†

, Hifza Javed², Mohammed Aldosari³, Thomas W. Frazier⁴ and Haitham Elbashir⁵

¹ Mechanical and Industrial Engineering Department, Qatar University, Doha 2713, Qatar

² Biomedical Engineering Department, George Washington University, Washington, DC 20052, USA

³ Center for Pediatric Neurology, Cleveland Clinic, and Case Western Reserve University, Cleveland, OH 44106, USA

⁴ Center for Autism Pediatric Institute, Cleveland Clinic and Cleveland Clinic Lerner College of Medicine, Cleveland, OH 44195, USA

⁵ Al Jalila Children’s Specialty Hospital, Dubai, United Arab Emirates

^† Current address: College of Engineering, Qatar University, Doha 2713, Qatar

Sensors 2017, 17(1), 46; https://doi.org/10.3390/s17010046 - 27 Dec 2016

Cited by 59 | Viewed by 12879

Abstract

This paper reviews the state-of-the-art in sensing technologies that are relevant for Autism Spectrum Disorder (ASD) screening and therapy. This disorder is characterized by difficulties in social communication, social interactions, and repetitive behaviors. It is diagnosed during the first three years of life. [...] Read more.

This paper reviews the state-of-the-art in sensing technologies that are relevant for Autism Spectrum Disorder (ASD) screening and therapy. This disorder is characterized by difficulties in social communication, social interactions, and repetitive behaviors. It is diagnosed during the first three years of life. Early and intensive interventions have been shown to improve the developmental trajectory of the affected children. The earlier the diagnosis, the sooner the intervention therapy can begin, thus, making early diagnosis an important research goal. Technological innovations have tremendous potential to assist with early diagnosis and improve intervention programs. The need for careful and methodological evaluation of such emerging technologies becomes important in order to assist not only the therapists and clinicians in their selection of suitable tools, but to also guide the developers of the technologies in improving hardware and software. In this paper, we survey the literatures on sensing technologies for ASD and we categorize them into eye trackers, movement trackers, electrodermal activity monitors, tactile sensors, vocal prosody and speech detectors, and sleep quality assessment devices. We assess their effectiveness and study their limitations. We also examine the challenges faced by this growing field that need to be addressed before these technologies can perform up to their theoretical potential. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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12 pages, 3318 KiB

Open AccessArticle

A Fiber-Optic Interferometric Tri-Component Geophone for Ocean Floor Seismic Monitoring

by Jiandong Chen¹, Tianying Chang^1,2,*

, Qunjian Fu¹, Jinpeng Lang¹, Wenzhi Gao¹, Zhongmin Wang², Miao Yu¹, Yanbo Zhang² and Hong-Liang Cui¹

¹ College of Instrumentation & Electrical Engineering, Jilin University, Changchun 130061, China

² Institute of Automation, Shandong Academy of Sciences, Jinan 250014, China

Sensors 2017, 17(1), 47; https://doi.org/10.3390/s17010047 - 28 Dec 2016

Cited by 50 | Viewed by 10756

Abstract

For the implementation of an all fiber observation network for submarine seismic monitoring, a tri-component geophone based on Michelson interferometry is proposed and tested. A compliant cylinder-based sensor head is analyzed with finite element method and tested. The operation frequency ranges from 2 [...] Read more.

For the implementation of an all fiber observation network for submarine seismic monitoring, a tri-component geophone based on Michelson interferometry is proposed and tested. A compliant cylinder-based sensor head is analyzed with finite element method and tested. The operation frequency ranges from 2 Hz to 150 Hz for acceleration detection, employing a phase generated carrier demodulation scheme, with a responsivity above 50 dB re rad/g for the whole frequency range. The transverse suppression ratio is about 30 dB. The system noise at low frequency originated mainly from the 1/f fluctuation, with an average system noise level −123.55

dB re rad / \sqrt{Hz}

ranging from 0 Hz to 500 Hz. The minimum detectable acceleration is about 2

ng / \sqrt{Hz}

, and the dynamic range is above 116 dB. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2016)

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12 pages, 2915 KiB

Open AccessArticle

Influence of Individual Differences on the Calculation Method for FBG-Type Blood Pressure Sensors

by Shouhei Koyama^1,*

, Hiroaki Ishizawa¹, Keisaku Fujimoto², Shun Chino³ and Yuka Kobayashi³

¹ Institute for Fiber Engineering, Shinshu University, 3-15-1 Tokida, Ueda City, Nagano 386-8567, Japan

² Department of Clinical Laboratory Sciences, School of Health Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto City, Nagano 390-8621, Japan

³ Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda City, Nagano 386-8567, Japan

Sensors 2017, 17(1), 48; https://doi.org/10.3390/s17010048 - 28 Dec 2016

Cited by 37 | Viewed by 6639

Abstract

In this paper, we propose a blood pressure calculation and associated measurement method that by using a fiber Bragg grating (FBG) sensor. There are several points at which the pulse can be measured on the surface of the human body, and when a [...] Read more.

In this paper, we propose a blood pressure calculation and associated measurement method that by using a fiber Bragg grating (FBG) sensor. There are several points at which the pulse can be measured on the surface of the human body, and when a FBG sensor located at any of these points, the pulse wave signal can be measured. The measured waveform is similar to the acceleration pulse wave. The pulse wave signal changes depending on several factors, including whether or not the individual is healthy and/or elderly. The measured pulse wave signal can be used to calculate the blood pressure using a calibration curve, which is constructed by a partial least squares (PLS) regression analysis using a reference blood pressure and the pulse wave signal. In this paper, we focus on the influence of individual differences from calculated blood pressure based on each calibration curve. In our study, the calculated blood pressure from both the individual and overall calibration curves were compared, and our results show that the calculated blood pressure based on the overall calibration curve had a lower measurement accuracy than that based on an individual calibration curve. We also found that the influence of the individual differences on the calculated blood pressure when using the FBG sensor method were very low. Therefore, the FBG sensor method that we developed for measuring the blood pressure was found to be suitable for use by many people. Full article

(This article belongs to the Special Issue Recent Advances in Fiber Bragg Grating Sensing)

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16 pages, 4527 KiB

Open AccessArticle

Multi-Objective Sliding Mode Control on Vehicle Cornering Stability with Variable Gear Ratio Actuator-Based Active Front Steering Systems

by Xinbo Ma¹, Pak Kin Wong¹

, Jing Zhao^1,* and Zhengchao Xie²

¹ Department of Electromechanical Engineering, University of Macau, Taipa, Macau 999078, China

² School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510641, China

Sensors 2017, 17(1), 49; https://doi.org/10.3390/s17010049 - 28 Dec 2016

Cited by 19 | Viewed by 8373

Abstract

Active front steering (AFS) is an emerging technology to improve the vehicle cornering stability by introducing an additional small steering angle to the driver’s input. This paper proposes an AFS system with a variable gear ratio steering (VGRS) actuator which is controlled by [...] Read more.

Active front steering (AFS) is an emerging technology to improve the vehicle cornering stability by introducing an additional small steering angle to the driver’s input. This paper proposes an AFS system with a variable gear ratio steering (VGRS) actuator which is controlled by using the sliding mode control (SMC) strategy to improve the cornering stability of vehicles. In the design of an AFS system, different sensors are considered to measure the vehicle state, and the mechanism of the AFS system is also modelled in detail. Moreover, in order to improve the cornering stability of vehicles, two dependent objectives, namely sideslip angle and yaw rate, are considered together in the design of SMC strategy. By evaluating the cornering performance, Sine with Dwell and accident avoidance tests are conducted, and the simulation results indicate that the proposed SMC strategy is capable of improving the cornering stability of vehicles in practice. Full article

(This article belongs to the Special Issue Vehicular Sensor Networks: Technical Challenges, Supports, and Application Experiences)

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14 pages, 4269 KiB

Open AccessArticle

A Fully Transparent Flexible Sensor for Cryogenic Temperatures Based on High Strength Metallurgical Graphene

by Ryszard Pawlak^1,*, Marcin Lebioda¹

, Jacek Rymaszewski¹, Witold Szymanski²

, Lukasz Kolodziejczyk²

and Piotr Kula²

¹ Institute of Electrical Engineering Systems, Lodz University of Technology, 90-924 Lodz, Poland

² Institute of Materials Science and Engineering, Lodz University of Technology, 90-924 Lodz, Poland

Sensors 2017, 17(1), 51; https://doi.org/10.3390/s17010051 - 28 Dec 2016

Cited by 27 | Viewed by 9700

Abstract

Low-temperature electronics operating in below zero temperatures or even below the lower limit of the common −65 to 125 °C temperature range are essential in medical diagnostics, in space exploration and aviation, in processing and storage of food and mainly in scientific research, [...] Read more.

Low-temperature electronics operating in below zero temperatures or even below the lower limit of the common −65 to 125 °C temperature range are essential in medical diagnostics, in space exploration and aviation, in processing and storage of food and mainly in scientific research, like superconducting materials engineering and their applications—superconducting magnets, superconducting energy storage, and magnetic levitation systems. Such electronic devices demand special approach to the materials used in passive elements and sensors. The main goal of this work was the implementation of a fully transparent, flexible cryogenic temperature sensor with graphene structures as sensing element. Electrodes were made of transparent ITO (Indium Tin Oxide) or ITO/Ag/ITO conductive layers by laser ablation and finally encapsulated in a polymer coating. A helium closed-cycle cryostat has been used in measurements of the electrical properties of these graphene-based temperature sensors under cryogenic conditions. The sensors were repeatedly cooled from room temperature to cryogenic temperature. Graphene structures were characterized using Raman spectroscopy. The observation of the resistance changes as a function of temperature indicates the potential use of graphene layers in the construction of temperature sensors. The temperature characteristics of the analyzed graphene sensors exhibit no clear anomalies or strong non-linearity in the entire studied temperature range (as compared to the typical carbon sensor). Full article

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

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10 pages, 2558 KiB

Open AccessArticle

Relative Estimation of Water Content for Flat-Type Inductive-Based Oil Palm Fruit Maturity Sensor

by Norhisam Misron^1,2,*, Nor Aziana Aliteh¹

, Noor Hasmiza Harun³, Kunihisa Tashiro⁴, Toshiro Sato⁴ and Hiroyuki Wakiwaka⁴

¹ Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia

² Institute of Advance Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia

³ Medical Engineering Section, Universiti Kuala Lumpur-British Malaysia Institute, Batu 8, Jalan Sg Pusu, 53100 Gombak, Selangor, Malaysia

⁴ Faculty of Engineering, Shinshu University, Wakasato 4-17-1, Nagano 380-8553, Japan

Sensors 2017, 17(1), 52; https://doi.org/10.3390/s17010052 - 28 Dec 2016

Cited by 24 | Viewed by 6874

Abstract

The paper aims to study the sensor that identifies the maturity of oil palm fruit bunches by using a flat-type inductive concept based on a resonant frequency technique. Conventionally, a human grader is used to inspect the ripeness of the oil palm fresh [...] Read more.

The paper aims to study the sensor that identifies the maturity of oil palm fruit bunches by using a flat-type inductive concept based on a resonant frequency technique. Conventionally, a human grader is used to inspect the ripeness of the oil palm fresh fruit bunch (FFB) which can be inconsistent and inaccurate. There are various new methods that are proposed with the intention to grade the ripeness of the oil palm FFB, but none has taken the inductive concept. In this study, the resonance frequency of the air coil is investigated. Samples of oil palm FFB are tested with frequencies ranging from 20 Hz to 10 MHz and the results obtained show a linear relationship between the graph of the resonance frequency (MHz) against time (Weeks). It is observed that the resonance frequencies obtained for Week 10 (pre-mature) and Week 18 (mature) are around 8.5 MHz and 9.8 MHz, respectively. These results are compared with the percentage of the moisture content. Hence, the inductive method of the oil palm fruit maturity sensor can be used to detect the change in water content for ripeness detection of the oil palm FFB. Full article

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

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18 pages, 518 KiB

Open AccessArticle

RFID Ownership Transfer with Positive Secrecy Capacity Channels

by Jorge Munilla^1,*

, Mike Burmester²

, Alberto Peinado¹, Guomin Yang³ and Willy Susilo³

¹ Escuela Técnica Superior de Ingenieros de Telecomunicación, Universidad de Málaga, Málaga 29071, Spain

² Department of Computer Science, Florida State University, Tallahassee, FL 32306, USA

³ School of Computer Science and Software Engineering, University of Wollongong, Wollongong, NSW 2522, Australia

Sensors 2017, 17(1), 53; https://doi.org/10.3390/s17010053 - 29 Dec 2016

Cited by 6 | Viewed by 4552

Abstract

RFID ownership transfer protocols (OTPs) transfer tag ownership rights. Recently, there has been considerable interest in such protocols; however, guaranteeing privacy for symmetric-key settings without trusted third parties (TTPs) is a challenge still unresolved. In this paper, we address this issue and show [...] Read more.

RFID ownership transfer protocols (OTPs) transfer tag ownership rights. Recently, there has been considerable interest in such protocols; however, guaranteeing privacy for symmetric-key settings without trusted third parties (TTPs) is a challenge still unresolved. In this paper, we address this issue and show that it can be solved by using channels with positive secrecy capacity. We implement these channels with noisy tags and provide practical values, thus proving that perfect secrecy is theoretically possible. We then define a communication model that captures spatiotemporal events and describe a first example of symmetric-key based OTP that: (i) is formally secure in the proposed communication model and (ii) achieves privacy with a noisy tag wiretap channel without TTPs. Full article

(This article belongs to the Section Sensor Networks)

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10 pages, 3238 KiB

Open AccessArticle

A Simple Interfacial Platform for Homogeneous Electrochemical Immunoassays Using a Poly(Vinylimidazole)-Modified Electrode

by Young-Bong Choi¹, Won-Yong Jeon² and Hyug-Han Kim^1,*

¹ Department of Chemistry, College of Natural Science, Dankook University, Anseo-Dong, Cheonan, Chungnam 330-714, Korea

² Department of Nanobiomedical Sciences and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Anseo-Dong, Cheonan, Chungnam 330-714, Korea

Sensors 2017, 17(1), 54; https://doi.org/10.3390/s17010054 - 29 Dec 2016

Cited by 6 | Viewed by 6466

Abstract

In this study, a homogeneous method featuring simple, one-step detection was developed to analyze hippuric acid (HA), a major metabolite of toluene. High sensitivity was achieved with the facile immobilization of poly(vinylimidazole) (PVI) on an indium tin oxide (ITO) electrode. Using a previously [...] Read more.

In this study, a homogeneous method featuring simple, one-step detection was developed to analyze hippuric acid (HA), a major metabolite of toluene. High sensitivity was achieved with the facile immobilization of poly(vinylimidazole) (PVI) on an indium tin oxide (ITO) electrode. Using a previously developed approach, pentacyanoferrate was coordinated with pyridyl-N ligands, and the redox-active Fe(II/III) centers were bound to Ni(II) ions on the electrode via electrostatic cyanide bridges. The detection was accomplished by the competitive binding of free HA and pentacyanoferrate-(4-aminomethylpyridine-hippuric acid) (Fe-HA, the electron transfer mediator) to the HA antibody on the Ni(II) ions-modified PVI-ITO (Ni-PVI-ITO) electrode. The electrical and physicochemical characterization of the electrode was carried out by cyclic voltammetry, differential pulse voltammetry, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. At low mediator concentrations, the electrical signals were proportional to the HA concentration between 0.1 µg/mL and 1.0 mg/mL. The same method may be extended to other small organic molecules. Full article

(This article belongs to the Special Issue Electrochemical Immunosensors)

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21 pages, 16437 KiB

Open AccessArticle

Honey Bee Colonies Remote Monitoring System

by Sergio Gil-Lebrero¹, Francisco Javier Quiles-Latorre²

, Manuel Ortiz-López^2,*

, Víctor Sánchez-Ruiz², Victoria Gámiz-López¹ and Juan Jesús Luna-Rodríguez²

¹ Department of Zoology, University of Córdoba, Córdoba 14071, Spain

² Department of Computer Architecture, Electronics and Electronic Technology, University of Córdoba, Córdoba 14071, Spain

Sensors 2017, 17(1), 55; https://doi.org/10.3390/s17010055 - 29 Dec 2016

Cited by 95 | Viewed by 21107

Abstract

Bees are very important for terrestrial ecosystems and, above all, for the subsistence of many crops, due to their ability to pollinate flowers. Currently, the honey bee populations are decreasing due to colony collapse disorder (CCD). The reasons for CCD are not fully [...] Read more.

Bees are very important for terrestrial ecosystems and, above all, for the subsistence of many crops, due to their ability to pollinate flowers. Currently, the honey bee populations are decreasing due to colony collapse disorder (CCD). The reasons for CCD are not fully known, and as a result, it is essential to obtain all possible information on the environmental conditions surrounding the beehives. On the other hand, it is important to carry out such information gathering as non-intrusively as possible to avoid modifying the bees’ work conditions and to obtain more reliable data. We designed a wireless-sensor networks meet these requirements. We designed a remote monitoring system (called WBee) based on a hierarchical three-level model formed by the wireless node, a local data server, and a cloud data server. WBee is a low-cost, fully scalable, easily deployable system with regard to the number and types of sensors and the number of hives and their geographical distribution. WBee saves the data in each of the levels if there are failures in communication. In addition, the nodes include a backup battery, which allows for further data acquisition and storage in the event of a power outage. Unlike other systems that monitor a single point of a hive, the system we present monitors and stores the temperature and relative humidity of the beehive in three different spots. Additionally, the hive is continuously weighed on a weighing scale. Real-time weight measurement is an innovation in wireless beehive—monitoring systems. We designed an adaptation board to facilitate the connection of the sensors to the node. Through the Internet, researchers and beekeepers can access the cloud data server to find out the condition of their hives in real time. Full article

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

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16 pages, 5273 KiB

Open AccessArticle

Target Detection over the Diurnal Cycle Using a Multispectral Infrared Sensor

by Huijie Zhao, Zheng Ji, Na Li^*, Jianrong Gu and Yansong Li

School of Instrumentation Science & Opto-Electronics Engineering, Beihang University, 37 Xueyuan Road, Haidian District, Beijing 100191, China

Sensors 2017, 17(1), 56; https://doi.org/10.3390/s17010056 - 29 Dec 2016

Cited by 9 | Viewed by 6238

Abstract

When detecting a target over the diurnal cycle, a conventional infrared thermal sensor might lose the target due to the thermal crossover, which could happen at any time throughout the day when the infrared image contrast between target and background in a scene [...] Read more.

When detecting a target over the diurnal cycle, a conventional infrared thermal sensor might lose the target due to the thermal crossover, which could happen at any time throughout the day when the infrared image contrast between target and background in a scene is indistinguishable due to the temperature variation. In this paper, the benefits of using a multispectral-based infrared sensor over the diurnal cycle have been shown. Firstly, a brief theoretical analysis on how the thermal crossover influences a conventional thermal sensor, within the conditions where the thermal crossover would happen and why the mid-infrared (3~5 μm) multispectral technology is effective, is presented. Furthermore, the effectiveness of this technology is also described and we describe how the prototype design and multispectral technology is employed to help solve the thermal crossover detection problem. Thirdly, several targets are set up outside and imaged in the field experiment over a 24-h period. The experimental results show that the multispectral infrared imaging system can enhance the contrast of the detected images and effectively solve the failure of the conventional infrared sensor during the diurnal cycle, which is of great significance for infrared surveillance applications. Full article

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

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21 pages, 886 KiB

Open AccessArticle

Design of a Mobile Low-Cost Sensor Network Using Urban Buses for Real-Time Ubiquitous Noise Monitoring

by Rosa Ma Alsina-Pagès^1,*

, Unai Hernandez-Jayo^2,3, Francesc Alías¹

and Ignacio Angulo^2,3

¹ GTM—Grup de recerca en Tecnologies Mèdia, La Salle-Universitat Ramon Llull, Quatre Camins, 30, Barcelona 08022, Spain

² DeustoTech—Fundación Deusto, Avda. Universidades, 24, Bilbao 48007, Spain

³ Facultad Ingeniería, Universidad de Deusto, Avda. Universidades, 24, Bilbao 48007, Spain

Sensors 2017, 17(1), 57; https://doi.org/10.3390/s17010057 - 29 Dec 2016

Cited by 41 | Viewed by 9999

Abstract

One of the main priorities of smart cities is improving the quality of life of their inhabitants. Traffic noise is one of the pollutant sources that causes a negative impact on the quality of life of citizens, which is gaining attention among authorities. [...] Read more.

One of the main priorities of smart cities is improving the quality of life of their inhabitants. Traffic noise is one of the pollutant sources that causes a negative impact on the quality of life of citizens, which is gaining attention among authorities. The European Commission has promoted the Environmental Noise Directive 2002/49/EC (END) to inform citizens and to prevent the harmful effects of noise exposure. The measure of acoustic levels using noise maps is a strategic issue in the END action plan. Noise maps are typically calculated by computing the average noise during one year and updated every five years. Hence, the implementation of dynamic noise mapping systems could lead to short-term plan actions, besides helping to better understand the evolution of noise levels along time. Recently, some projects have started the monitoring of noise levels in urban areas by means of acoustic sensor networks settled in strategic locations across the city, while others have taken advantage of collaborative citizen sensing mobile applications. In this paper, we describe the design of an acoustic low-cost sensor network installed on public buses to measure the traffic noise in the city in real time. Moreover, the challenges that a ubiquitous bus acoustic measurement system entails are enumerated and discussed. Specifically, the analysis takes into account the feature extraction of the audio signal, the identification and separation of the road traffic noise from urban traffic noise, the hardware platform to measure and process the acoustic signal, the connectivity between the several nodes of the acoustic sensor network to store the data and, finally, the noise maps’ generation process. The implementation and evaluation of the proposal in a real-life scenario is left for future work. Full article

(This article belongs to the Special Issue Smart City: Vision and Reality)

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16 pages, 4375 KiB

Open AccessArticle

Odor-Sensing System to Support Social Participation of People Suffering from Incontinence

by Alvaro Ortiz Pérez¹, Vera Kallfaß-de Frenes², Alexander Filbert³, Janosch Kneer¹, Benedikt Bierer¹, Pirmin Held⁴, Philipp Klein⁴, Jürgen Wöllenstein^1,5, Dirk Benyoucef⁴, Sigrid Kallfaß², Ulrich Mescheder³ and Stefan Palzer^1,*

¹ Laboratory for Gas Sensors, Department of Microsystems Engineering, University of Freiburg, Freiburg 79110, Germany

² Steinbeis Transfer Center, Social Planning, Qualification and Innovation, Meersburg 88709, Germany

³ Institute for Microsystems Technology, Mechanical and Medical Engineering, Furtwangen University, Furtwangen 78120, Germany

⁴ Signal Processing Research Group (ReSP), Mechanical and Medical Engineering, Furtwangen University, Furtwangen 78120, Germany

⁵ Fraunhofer Institute for Physical Measurement Techniques (IPM), Freiburg 79110, Germany

Sensors 2017, 17(1), 58; https://doi.org/10.3390/s17010058 - 29 Dec 2016

Cited by 12 | Viewed by 8580

Abstract

This manuscript describes the design considerations, implementation, and laboratory validation of an odor sensing module whose purpose is to support people that suffer from incontinence. Because of the requirements expressed by the affected end-users the odor sensing unit is realized as a portable [...] Read more.

This manuscript describes the design considerations, implementation, and laboratory validation of an odor sensing module whose purpose is to support people that suffer from incontinence. Because of the requirements expressed by the affected end-users the odor sensing unit is realized as a portable accessory that may be connected to any pre-existing smart device. We have opted for a low-cost, low-power consuming metal oxide based gas detection approach to highlight the viability of developing an inexpensive yet helpful odor recognition technology. The system consists of a hotplate employing, inkjet-printed p-type semiconducting layers of copper(II) oxide, and chromium titanium oxide. Both functional layers are characterized with respect to their gas-sensitive behavior towards humidity, ammonia, methylmercaptan, and dimethylsulfide and we demonstrate detection limits in the parts-per-billion range for the two latter gases. Employing a temperature variation scheme that reads out the layer’s resistivity in a steady-state, we use each sensor chip as a virtual array. With this setup, we demonstrate the feasibility of detecting odors associated with incontinence. Full article

(This article belongs to the Special Issue Olfactory and Gustatory Sensors)

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23 pages, 10748 KiB

Open AccessArticle

Concept and Development of an Electronic Framework Intended for Electrode and Surrounding Environment Characterization In Vivo

by Stefan B. Rieger^1,2,†, Jennifer Pfau^1,*, Thomas Stieglitz^1,3

, Maria Asplund^1,3 and Juan S. Ordonez^1,4,5,*,†

¹ Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Köhler-Allee 102, 79110 Freiburg, Germany

² Cortec GmbH, Georges-Köhler Allee 010, 79110 Freiburg, Germany

³ BrainLinks-BrainTools Center, University of Freiburg, Georges-Köhler-Allee 79, 79110 Freiburg, Germany

⁴ Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Albertstraße 19, 79104 Freiburg, Germany

⁵ Medtronic, Medtronic Eindhoven Design Center, Neuromodulation High Tech Campus 41, 5656 AE Eindhoven, The Netherlands

^† This work was performed at a time when the authors’ affiliations were 1 and or 4.

Sensors 2017, 17(1), 59; https://doi.org/10.3390/s17010059 - 30 Dec 2016

Cited by 3 | Viewed by 10343

Abstract

There has been substantial progress over the last decade towards miniaturizing implantable microelectrodes for use in Active Implantable Medical Devices (AIMD). Compared to the rapid development and complexity of electrode miniaturization, methods to monitor and assess functional integrity and electrical functionality of these [...] Read more.

There has been substantial progress over the last decade towards miniaturizing implantable microelectrodes for use in Active Implantable Medical Devices (AIMD). Compared to the rapid development and complexity of electrode miniaturization, methods to monitor and assess functional integrity and electrical functionality of these electrodes, particularly during long term stimulation, have not progressed to the same extent. Evaluation methods that form the gold standard, such as stimulus pulse testing, cyclic voltammetry and electrochemical impedance spectroscopy, are either still bound to laboratory infrastructure (impractical for long term in vivo experiments) or deliver no comprehensive insight into the material’s behaviour. As there is a lack of cost effective and practical predictive measures to understand long term electrode behaviour in vivo, material investigations need to be performed after explantation of the electrodes. We propose the analysis of the electrode and its environment in situ, to better understand and correlate the effects leading to electrode failure. The derived knowledge shall eventually lead to improved electrode designs, increased electrode functionality and safety in clinical applications. In this paper, the concept, design and prototyping of a sensor framework used to analyse the electrode’s behaviour and to monitor diverse electrode failure mechanisms, even during stimulation pulses, is presented. We focused on the electronic circuitry and data acquisition techniques required for a conceptual multi-sensor system. Functionality of single modules and a prototype framework have been demonstrated, but further work is needed to convert the prototype system into an implantable device. In vitro studies will be conducted first to verify sensor performance and reliability. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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21 pages, 23324 KiB

Open AccessArticle

SCRMS: An RFID and Sensor Web-Enabled Smart Cultural Relics Management System

by Changjiang Xiao^1,2

, Nengcheng Chen^1,2,*

, Dandan Li¹, You Lv¹ and Jianya Gong^1,2,3

¹ State Key Lab for Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

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

³ School of Remote Sensing and Information Engineering, 129 Luoyu Road, Wuhan 430079, China

Sensors 2017, 17(1), 60; https://doi.org/10.3390/s17010060 - 30 Dec 2016

Cited by 18 | Viewed by 9074

Abstract

Cultural relics represent national or even global resources of inestimable value. How to efficiently manage and preserve these cultural relics is a vitally important issue. To achieve this goal, this study proposed, designed, and implemented an RFID and Sensor Web–enabled smart cultural relics [...] Read more.

Cultural relics represent national or even global resources of inestimable value. How to efficiently manage and preserve these cultural relics is a vitally important issue. To achieve this goal, this study proposed, designed, and implemented an RFID and Sensor Web–enabled smart cultural relics management system (SCRMS). In this system, active photovoltaic subtle energy-powered Radio Frequency Identification (RFID) is used for long-range contactless identification and lifecycle management of cultural relics during their storage and circulation. In addition, different types of ambient sensors are integrated with the RFID tags and deployed around cultural relics to monitor their environmental parameters, helping to ensure that they remain in good condition. An Android-based smart mobile application, as middleware, is used in collaboration with RFID readers to collect information and provide convenient management for the circulation of cultural relics. Moreover, multiple sensing techniques are taken advantage of simultaneously for preservation of cultural relics. The proposed system was successfully applied to a museum in the Yongding District, Fujian Province, China, demonstrating its feasibility and advantages for smart and efficient management and preservation of cultural relics. Full article

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

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8 pages, 2077 KiB

Open AccessArticle

In Situ Real-Time Monitoring of Glutamate and Electrophysiology from Cortex to Hippocampus in Mice Based on a Microelectrode Array

by Xinyi Fan^1,2

, Yilin Song^1,2, Yuanlin Ma³, Song Zhang^1,2, Guihua Xiao^1,2, Lili Yang^1,2, Huiren Xu^1,2, Dai Zhang³ and Xinxia Cai^1,2,*

¹ State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

² University of Chinese Academy of Sciences, Beijing 100190, China

³ Institute of Mental Health, the Sixth Hospital of Peking University, Beijing 100191, China

Sensors 2017, 17(1), 61; https://doi.org/10.3390/s17010061 - 30 Dec 2016

Cited by 23 | Viewed by 7553

Abstract

Changes in the structure and function of the hippocampus contribute to epilepsy, schizophrenia and other neurological or mental disorders of the brain. Since the function of the hippocampus depends heavily on the glutamate (Glu) signaling pathways, in situ real-time detection of Glu neurotransmitter [...] Read more.

Changes in the structure and function of the hippocampus contribute to epilepsy, schizophrenia and other neurological or mental disorders of the brain. Since the function of the hippocampus depends heavily on the glutamate (Glu) signaling pathways, in situ real-time detection of Glu neurotransmitter release and electrophysiological signals in hippocampus is of great significance. To achieve the dual-mode detection in mouse hippocampus in vivo, a 16-channel implantable microelectrode array (MEA) was fabricated by micro-electromechanical system (MEMS) technology. Twelve microelectrode sites were modified with platinum black for electrophysiological recording and four sites were modified with glutamate oxidase (GluOx) and 1,3-phenylenediamine (mPD) for selective electrochemical detection of Glu. The MEA was implanted from cortex to hippocampus in mouse brain for in situ real-time monitoring of Glu and electrophysiological signals. It was found that the Glu concentration in hippocampus was roughly 50 μM higher than that in the cortex, and the firing rate of concurrently recorded spikes declined from 6.32 ± 4.35 spikes/s in cortex to 0.09 ± 0.06 spikes/s in hippocampus. The present results demonstrated that the dual-mode MEA probe was capable in neurological detections in vivo with high spatial resolution and dynamical response, which lays the foundation for further pathology studies in the hippocampus of mouse models with nervous or mental disorders. Full article

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

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18 pages, 9472 KiB

Open AccessArticle

Modeling, Fabrication and Testing of a Customizable Micromachined Hotplate for Sensor Applications

by Alessio Tommasi^1,*

, Matteo Cocuzza^1,2

, Denis Perrone³, Candido Fabrizio Pirri^1,3

, Roberto Mosca², Marco Villani²

, Nicola Delmonte⁴

, Andrea Zappettini², Davide Calestani² and Simone Luigi Marasso^1,2

¹ χlab—Materials and Microsystems Laboratory, Department of Applied Science and Technology, Politecnico di Torino—Via Lungo Piazza d’Armi 6, 10034 Chivasso, Turin, Italy

² Istituto Materiali per Elettronica e Magnetismo, Consiglio Nazionale delle Ricerche, Parco Area delle Scienze, 37a, 43124 Parma, Italy

³ Italian Institute of Technology, Center for Sustainable Futures, C.so Trento 21, 10129 Torino, Italy

⁴ Department of Information Engineering, University of Parma, Parco Area delle Scienze 181/A, 43124 Parma, Italy

Sensors 2017, 17(1), 62; https://doi.org/10.3390/s17010062 - 30 Dec 2016

Cited by 25 | Viewed by 8775

Abstract

In the sensors field the active sensing material frequently needs a controlled temperature in order to work properly. In microsystems technology, micro-machined hotplates represent a platform consisting of a thin suspended membrane where the sensing material can be deposited, usually integrating electrical stimuli [...] Read more.

In the sensors field the active sensing material frequently needs a controlled temperature in order to work properly. In microsystems technology, micro-machined hotplates represent a platform consisting of a thin suspended membrane where the sensing material can be deposited, usually integrating electrical stimuli and temperature readout. The micro-hotplate ensures a series of advantages such as miniaturized size, fast response, high sensitivity, low power consumption and selectivity for chemical sensing. This work compares the coplanar and the buried approach for the micro-hotplate heaters design with the aim to optimize the fabrication process and to propose a guideline for the choice of the suitable design with respect to the applications. In particular, robust Finite Element Method (FEM) models are set up in order to predict the electrical and thermal behavior of the micro-hotplates. The multiphysics approach used for the simulation allows to match as close as possible the actual device to the predictive model: geometries, materials, physics have been carefully linked to the fabricated devices to obtain the best possible accuracy. The materials involved in the fabrication process are accurately selected in order to improve the yield of the process and the performance of the devices. The fabricated micro-hotplates are able to warm the active region up to 400 °C (with a corresponding power consumption equal to 250 mW @ 400 °C) with a uniform temperature distribution in the buried micro-hotplate and a controlled temperature gradient in the coplanar one. A response time of about 70 ms was obtained on the virtual model, which perfectly agrees with the one measured on the fabricated device. Besides morphological, electrical and thermal characterizations, this work includes reliability tests in static and dynamic modes. Full article

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

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12 pages, 3292 KiB

Open AccessArticle

Integration of Curved D-Type Optical Fiber Sensor with Microfluidic Chip

by Yung-Shin Sun^1,*

, Chang-Jyun Li¹ and Jin-Cherng Hsu^1,2

¹ Department of Physics, Fu-Jen Catholic University, New Taipei City 24205, Taiwan

² Graduate Institute of Applied Science and Engineering, Fu-Jen Catholic University, New Taipei City 24205, Taiwan

Sensors 2017, 17(1), 63; https://doi.org/10.3390/s17010063 - 30 Dec 2016

Cited by 20 | Viewed by 6062

Abstract

A curved D-type optical fiber sensor (OFS) combined with a microfluidic chip is proposed. This OFS, based on surface plasmon resonance (SPR) of the Kretchmann’s configuration, is applied as a biosensor to measure the concentrations of different bio-liquids such as ethanol, methanol, and [...] Read more.

A curved D-type optical fiber sensor (OFS) combined with a microfluidic chip is proposed. This OFS, based on surface plasmon resonance (SPR) of the Kretchmann’s configuration, is applied as a biosensor to measure the concentrations of different bio-liquids such as ethanol, methanol, and glucose solutions. The SPR phenomenon is attained by using the optical fiber to guide the light source to reach the side-polished, gold-coated region. Integrating this OFS with a polymethylmethacrylate (PMMA)-based microfluidic chip, the SPR spectra for liquids with different refractive indices are recorded. Experimentally, the sensitivity of the current biosensor was calculated to be in the order of 10⁻⁵ RIU. This microfluidic chip-integrated OFS could be valuable for monitoring subtle changes in biological samples such as blood sugar, allergen, and biomolecular interactions. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 3189 KiB

Open AccessArticle

Novel Visual Sensor Coverage and Deployment in Time Aware PTZ Wireless Visual Sensor Networks

by Florence G. H. Yap¹ and Hong-Hsu Yen^2,*

¹ Center for General Education, Chang Gung University, Taoyuan 333, Taiwan

² Department of Information Management, Shih Hsin University, Taipei 116, Taiwan

Sensors 2017, 17(1), 64; https://doi.org/10.3390/s17010064 - 30 Dec 2016

Cited by 10 | Viewed by 5057

Abstract

In this paper, we consider the visual sensor deployment algorithm in Pan-Tilt-Zoom (PTZ) Wireless Visual Sensor Networks (WVSNs). With PTZ capability, a sensor’s visual coverage can be extended to reduce the number of visual sensors that need to be deployed. The coverage zone [...] Read more.

In this paper, we consider the visual sensor deployment algorithm in Pan-Tilt-Zoom (PTZ) Wireless Visual Sensor Networks (WVSNs). With PTZ capability, a sensor’s visual coverage can be extended to reduce the number of visual sensors that need to be deployed. The coverage zone of a visual sensor in PTZ WVSN is composed of two regions, a Direct Coverage Region (DCR) and a PTZ Coverage Region (PTZCR). In the PTZCR, a visual sensor needs a mechanical pan-tilt-zoom operation to cover an object. This mechanical operation can take seconds, so the sensor might not be able to adjust the camera in time to capture the visual data. In this paper, for the first time, we study this PTZ time-aware PTZ WVSN deployment problem. We formulate this PTZ time-aware PTZ WVSN deployment problem as an optimization problem where the objective is to minimize the total visual sensor deployment cost so that each area is either covered in the DCR or in the PTZCR while considering the PTZ time constraint. The proposed Time Aware Coverage Zone (TACZ) model successfully captures the PTZ visual sensor coverage in terms of camera focal range, angle span zone coverage and camera PTZ time. Then a novel heuristic, called Time Aware Deployment with PTZ camera (TADPTZ) algorithm, is proposed to solve the problem. From our computational experiments, we found out that TACZ model outperforms the existing M coverage model under all network scenarios. In addition, as compared to the optimal solutions, the TACZ model is scalable and adaptable to the different PTZ time requirements when deploying large PTZ WVSNs. Full article

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

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26 pages, 1240 KiB

Open AccessArticle

A Comparison Study of Classifier Algorithms for Cross-Person Physical Activity Recognition

by Yago Saez^*

, Alejandro Baldominos

and Pedro Isasi

Department of Computer Science, Universidad Carlos III de Madrid, 28911 Leganés, Spain

Sensors 2017, 17(1), 66; https://doi.org/10.3390/s17010066 - 30 Dec 2016

Cited by 51 | Viewed by 9558

Abstract

Physical activity is widely known to be one of the key elements of a healthy life. The many benefits of physical activity described in the medical literature include weight loss and reductions in the risk factors for chronic diseases. With the recent advances [...] Read more.

Physical activity is widely known to be one of the key elements of a healthy life. The many benefits of physical activity described in the medical literature include weight loss and reductions in the risk factors for chronic diseases. With the recent advances in wearable devices, such as smartwatches or physical activity wristbands, motion tracking sensors are becoming pervasive, which has led to an impressive growth in the amount of physical activity data available and an increasing interest in recognizing which specific activity a user is performing. Moreover, big data and machine learning are now cross-fertilizing each other in an approach called “deep learning”, which consists of massive artificial neural networks able to detect complicated patterns from enormous amounts of input data to learn classification models. This work compares various state-of-the-art classification techniques for automatic cross-person activity recognition under different scenarios that vary widely in how much information is available for analysis. We have incorporated deep learning by using Google’s TensorFlow framework. The data used in this study were acquired from PAMAP2 (Physical Activity Monitoring in the Ageing Population), a publicly available dataset containing physical activity data. To perform cross-person prediction, we used the leave-one-subject-out (LOSO) cross-validation technique. When working with large training sets, the best classifiers obtain very high average accuracies (e.g., 96% using extra randomized trees). However, when the data volume is drastically reduced (where available data are only 0.001% of the continuous data), deep neural networks performed the best, achieving 60% in overall prediction accuracy. We found that even when working with only approximately 22.67% of the full dataset, we can statistically obtain the same results as when working with the full dataset. This finding enables the design of more energy-efficient devices and facilitates cold starts and big data processing of physical activity records. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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10 pages, 3797 KiB

Open AccessArticle

Programmable Low-Power Low-Noise Capacitance to Voltage Converter for MEMS Accelerometers

by Guillermo Royo^1,*, Carlos Sánchez-Azqueta¹, Cecilia Gimeno², Concepción Aldea¹ and Santiago Celma¹

¹ Group of Electronic Design—Aragón Institute of Engineering Research, Universidad de Zaragoza, 50009 Zaragoza, Spain

² Institute of Information and Communication Technologies, Electronics and Applied Mathemathics, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium

Sensors 2017, 17(1), 67; https://doi.org/10.3390/s17010067 - 30 Dec 2016

Cited by 14 | Viewed by 7182

Abstract

In this work, we present a capacitance-to-voltage converter (CVC) for capacitive accelerometers based on microelectromechanical systems (MEMS). Based on a fully-differential transimpedance amplifier (TIA), it features a 34-dB transimpedance gain control and over one decade programmable bandwidth, from 75 kHz to 1.2 MHz. [...] Read more.

In this work, we present a capacitance-to-voltage converter (CVC) for capacitive accelerometers based on microelectromechanical systems (MEMS). Based on a fully-differential transimpedance amplifier (TIA), it features a 34-dB transimpedance gain control and over one decade programmable bandwidth, from 75 kHz to 1.2 MHz. The TIA is aimed for low-cost low-power capacitive sensor applications. It has been designed in a standard 0.18-μm CMOS technology and its power consumption is only 54 μW. At the maximum transimpedance configuration, the TIA shows an equivalent input noise of 42 fA/

\sqrt{Hz}

at 50 kHz, which corresponds to 100 μg/

\sqrt{Hz}

. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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22 pages, 4007 KiB

Open AccessArticle

SEALDH-II—An Autonomous, Holistically Controlled, First Principles TDLAS Hygrometer for Field and Airborne Applications: Design–Setup–Accuracy/Stability Stress Test

by Bernhard Buchholz^1,2,3, Sören Kallweit¹ and Volker Ebert^1,2,4,*

¹ Physikalisch-Technische Bundesanstalt Braunschweig, Braunschweig 38114, Germany

² Physikalisch Chemisches Institut, Universität Heidelberg, Heidelberg 69120, Germany

³ Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08540, USA

⁴ Center of Smart Interfaces, Technische Universität Darmstadt, Darmstadt 64287, Germany

Sensors 2017, 17(1), 68; https://doi.org/10.3390/s17010068 - 30 Dec 2016

Cited by 14 | Viewed by 6347

Abstract

Instrument operation in harsh environments often significantly impacts the trust level of measurement data. While commercial instrument manufacturers clearly define the deployment conditions to achieve trustworthy data in typical standard applications, it is frequently unavoidable in scientific field applications to operate instruments outside [...] Read more.

Instrument operation in harsh environments often significantly impacts the trust level of measurement data. While commercial instrument manufacturers clearly define the deployment conditions to achieve trustworthy data in typical standard applications, it is frequently unavoidable in scientific field applications to operate instruments outside these commercial standard application specifications. Scientific instrumentation, however, is employing cutting-edge technology and often highly optimized but also lacks long-term field tests to assess the field vs. laboratory performance. Recently, we developed the Selective Extractive Laser Diode Hygrometer (SEALDH-II), which addresses field and especially airborne applications as well as metrological laboratory validations. SEALDH-II targets reducing deviations between airborne hygrometers (currently up to 20% between the most advanced hygrometers) with a new holistic, internal control and validation concept, which guarantees the transfer of the laboratory performance into a field scenario by capturing more than 80 instrument internal “housekeeping” data to nearly perfectly control SEALDH-II’s health status. SEALDH-II uses a calibration-free, first principles based, direct Tuneable Diode Laser Absorption Spectroscopy (dTDLAS) approach, to cover the entire atmospheric humidity measurement range from about 3 to 40,000 ppmv with a calculated maximum uncertainty of 4.3% ± 3 ppmv. This is achieved not only by innovations in internal instrument monitoring and design, but also by active control algorithms such as a high resolution spectral stabilization. This paper describes the setup, working principles, and instrument stabilization, as well as its precision validation and long-term stress tests in an environmental chamber over an environmental temperature and humidity range of ΔT = 50 K and ΔRH = 80% RH, respectively. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 3159 KiB

Open AccessArticle

A Novel Secure IoT-Based Smart Home Automation System Using a Wireless Sensor Network

by Sandeep Pirbhulal^1,2,3,†, Heye Zhang^1,2,†, Md Eshrat E Alahi^4,5

, Hemant Ghayvat⁴, Subhas Chandra Mukhopadhyay^4,5,*, Yuan-Ting Zhang⁶ and Wanqing Wu^1,2,*

¹ Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China

² Research Center for Biomedical Information Technology, Shenzhen Institutes of Advanced Technology, 1068 Xueyuan Avenue, Shenzhen University Town, Shenzhen 518055, China

³ Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen 518055, China

⁴ School of Engineering and Advanced Technology, Massey University, Palmerston North 4442, New Zealand

⁵ Department of Engineering, Macquarie University, Sydney 2109, Australia

⁶ Joint Research Centre for Biomedical Engineering, Chinese University of Hong Kong, Shatin N.T., Hong Kong, China

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 69; https://doi.org/10.3390/s17010069 - 30 Dec 2016

Cited by 206 | Viewed by 23719

Abstract

Wireless sensor networks (WSNs) provide noteworthy benefits over traditional approaches for several applications, including smart homes, healthcare, environmental monitoring, and homeland security. WSNs are integrated with the Internet Protocol (IP) to develop the Internet of Things (IoT) for connecting everyday life objects to [...] Read more.

Wireless sensor networks (WSNs) provide noteworthy benefits over traditional approaches for several applications, including smart homes, healthcare, environmental monitoring, and homeland security. WSNs are integrated with the Internet Protocol (IP) to develop the Internet of Things (IoT) for connecting everyday life objects to the internet. Hence, major challenges of WSNs include: (i) how to efficiently utilize small size and low-power nodes to implement security during data transmission among several sensor nodes; (ii) how to resolve security issues associated with the harsh and complex environmental conditions during data transmission over a long coverage range. In this study, a secure IoT-based smart home automation system was developed. To facilitate energy-efficient data encryption, a method namely Triangle Based Security Algorithm (TBSA) based on efficient key generation mechanism was proposed. The proposed TBSA in integration of the low power Wi-Fi were included in WSNs with the Internet to develop a novel IoT-based smart home which could provide secure data transmission among several associated sensor nodes in the network over a long converge range. The developed IoT based system has outstanding performance by fulfilling all the necessary security requirements. The experimental results showed that the proposed TBSA algorithm consumed less energy in comparison with some existing methods. Full article

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

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20 pages, 9098 KiB

Open AccessArticle

Line-Based Registration of Panoramic Images and LiDAR Point Clouds for Mobile Mapping

by Tingting Cui^1,2, Shunping Ji^3,4,*, Jie Shan^5,6,*

, Jianya Gong^1,3,5 and Kejian Liu²

¹ State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China

² Research Center of Remote Sensing in Public Security, People’s Public Security University of China, Beijing 100038, China

³ School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China

⁴ RSISE, Australian National University, Canberra, ACT 2600, Australia

⁵ Collaborative Innovation Center of Geospatial Technology, Wuhan University, Wuhan 430079, China

⁶ Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA

Sensors 2017, 17(1), 70; https://doi.org/10.3390/s17010070 - 31 Dec 2016

Cited by 55 | Viewed by 9941

Abstract

For multi-sensor integrated systems, such as the mobile mapping system (MMS), data fusion at sensor-level, i.e., the 2D-3D registration between an optical camera and LiDAR, is a prerequisite for higher level fusion and further applications. This paper proposes a line-based registration method for [...] Read more.

For multi-sensor integrated systems, such as the mobile mapping system (MMS), data fusion at sensor-level, i.e., the 2D-3D registration between an optical camera and LiDAR, is a prerequisite for higher level fusion and further applications. This paper proposes a line-based registration method for panoramic images and a LiDAR point cloud collected by a MMS. We first introduce the system configuration and specification, including the coordinate systems of the MMS, the 3D LiDAR scanners, and the two panoramic camera models. We then establish the line-based transformation model for the panoramic camera. Finally, the proposed registration method is evaluated for two types of camera models by visual inspection and quantitative comparison. The results demonstrate that the line-based registration method can significantly improve the alignment of the panoramic image and the LiDAR datasets under either the ideal spherical or the rigorous panoramic camera model, with the latter being more reliable. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 2535 KiB

Open AccessArticle

Matched Field Processing Based on Least Squares with a Small Aperture Hydrophone Array

by Qi Wang^†, Yingmin Wang^† and Guolei Zhu^*,†

¹ School of Marine Science and Technology, Northwestern Polytechinal University, Xi’an 710072, China

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 71; https://doi.org/10.3390/s17010071 - 30 Dec 2016

Cited by 10 | Viewed by 4905

Abstract

The receiver hydrophone array is the signal front-end and plays an important role in matched field processing, which usually covers the whole water column from the sea surface to the bottom. Such a large aperture array is very difficult to realize. To solve [...] Read more.

The receiver hydrophone array is the signal front-end and plays an important role in matched field processing, which usually covers the whole water column from the sea surface to the bottom. Such a large aperture array is very difficult to realize. To solve this problem, an approach called matched field processing based on least squares with a small aperture hydrophone array is proposed, which decomposes the received acoustic fields into depth function matrix and amplitudes of the normal modes at the beginning. Then all the mode amplitudes are estimated using the least squares in the sense of minimum norm, and the amplitudes estimated are used to recalculate the received acoustic fields of the small aperture array, which means the recalculated ones contain more environmental information. In the end, lots of numerical experiments with three small aperture arrays are processed in the classical shallow water, and the performance of matched field passive localization is evaluated. The results show that the proposed method can make the recalculated fields contain more acoustic information of the source, and the performance of matched field passive localization with small aperture array is improved, so the proposed algorithm is proved to be effective. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 5779 KiB

Open AccessArticle

High-Precision Registration of Point Clouds Based on Sphere Feature Constraints

by Junhui Huang^1,*

, Zhao Wang^1,*, Jianmin Gao², Youping Huang¹ and David Peter Towers³

¹ Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China

² State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, China

³ School of Engineering, University of Warwick, Coventry CV4 7AL, UK

Sensors 2017, 17(1), 72; https://doi.org/10.3390/s17010072 - 30 Dec 2016

Cited by 26 | Viewed by 5725

Abstract

Point cloud registration is a key process in multi-view 3D measurements. Its precision affects the measurement precision directly. However, in the case of the point clouds with non-overlapping areas or curvature invariant surface, it is difficult to achieve a high precision. A high [...] Read more.

Point cloud registration is a key process in multi-view 3D measurements. Its precision affects the measurement precision directly. However, in the case of the point clouds with non-overlapping areas or curvature invariant surface, it is difficult to achieve a high precision. A high precision registration method based on sphere feature constraint is presented to overcome the difficulty in the paper. Some known sphere features with constraints are used to construct virtual overlapping areas. The virtual overlapping areas provide more accurate corresponding point pairs and reduce the influence of noise. Then the transformation parameters between the registered point clouds are solved by an optimization method with weight function. In that case, the impact of large noise in point clouds can be reduced and a high precision registration is achieved. Simulation and experiments validate the proposed method. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 2588 KiB

Open AccessArticle

Evaluation of Surface Cleaning Procedures in Terms of Gas Sensing Properties of Spray-Deposited CNT Film: Thermal- and O₂ Plasma Treatments

by Joon Hyub Kim¹, Min-Jung Song², Ki Beom Kim¹, Joon-Hyung Jin^3,4,* and Nam Ki Min^1,*

¹ Department of Electro-Mechanical Systems Engineering, Korea University, 2511 Sejong-ro, Sejong City 339-770, Korea

² College of Liberal Art & Interdisciplinary Studies, Kyonggi University, 154-42 Gwanggyosan-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-760, Korea

³ National Institute for Nanomaterial Technology, POSTECH 77, Cheongam-ro, Nam-gu, Phohang, Gyeongbuk 37673, Korea

⁴ Department of Chemical Engineering, Kyonggi University, 154-42 Gwanggyosan-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-760, Korea

Sensors 2017, 17(1), 73; https://doi.org/10.3390/s17010073 - 30 Dec 2016

Cited by 11 | Viewed by 5455

Abstract

The effect of cleaning the surface of single-walled carbon nanotube (SWNT) networks by thermal and the O₂ plasma treatments is presented in terms of NH₃ gas sensing characteristics. The goal of this work is to determine the relationship between the physicochemical [...] Read more.

The effect of cleaning the surface of single-walled carbon nanotube (SWNT) networks by thermal and the O₂ plasma treatments is presented in terms of NH₃ gas sensing characteristics. The goal of this work is to determine the relationship between the physicochemical properties of the cleaned surface (including the chemical composition, crystal structure, hydrophilicity, and impurity content) and the sensitivity of the SWNT network films to NH₃ gas. The SWNT networks are spray-deposited on pre-patterned Pt electrodes, and are further functionalized by heating on a programmable hot plate or by O₂ plasma treatment in a laboratory-prepared plasma chamber. Cyclic voltammetry was employed to semi-quantitatively evaluate each surface state of various plasma-treated SWNT-based electrodes. The results show that O₂ plasma treatment can more effectively modify the SWNT network surface than thermal cleaning, and can provide a better conductive network surface due to the larger number of carbonyl/carboxyl groups, enabling a faster electron transfer rate, even though both the thermal cleaning and the O₂ plasma cleaning methods can eliminate the organic solvent residues from the network surface. The NH₃ sensors based on the O₂ plasma-treated SWNT network exhibit higher sensitivity, shorter response time, and better recovery of the initial resistance than those prepared employing the thermally-cleaned SWNT networks. Full article

(This article belongs to the Special Issue Chemiresistive Sensors)

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22 pages, 6215 KiB

Open AccessArticle

Estimation of Ground Reaction Forces and Moments During Gait Using Only Inertial Motion Capture

by Angelos Karatsidis^1,4,*

, Giovanni Bellusci¹

, H. Martin Schepers¹, Mark De Zee²

, Michael S. Andersen³

and Peter H. Veltink⁴

¹ Xsens Technologies B.V., Enschede 7521 PR, The Netherlands

² Department of Health Science and Technology, Aalborg University, Aalborg 9220, Denmark

³ Department of Mechanical and Manufacturing Engineering, Aalborg University, Aalborg 9220, Denmark

⁴ Institute for Biomedical Technology and Technical Medicine (MIRA), University of Twente, Enschede 7500 AE, The Netherlands

Sensors 2017, 17(1), 75; https://doi.org/10.3390/s17010075 - 31 Dec 2016

Cited by 199 | Viewed by 26687

Abstract

Ground reaction forces and moments (GRF&M) are important measures used as input in biomechanical analysis to estimate joint kinetics, which often are used to infer information for many musculoskeletal diseases. Their assessment is conventionally achieved using laboratory-based equipment that cannot be applied in [...] Read more.

Ground reaction forces and moments (GRF&M) are important measures used as input in biomechanical analysis to estimate joint kinetics, which often are used to infer information for many musculoskeletal diseases. Their assessment is conventionally achieved using laboratory-based equipment that cannot be applied in daily life monitoring. In this study, we propose a method to predict GRF&M during walking, using exclusively kinematic information from fully-ambulatory inertial motion capture (IMC). From the equations of motion, we derive the total external forces and moments. Then, we solve the indeterminacy problem during double stance using a distribution algorithm based on a smooth transition assumption. The agreement between the IMC-predicted and reference GRF&M was categorized over normal walking speed as excellent for the vertical (ρ = 0.992, rRMSE = 5.3%), anterior (ρ = 0.965, rRMSE = 9.4%) and sagittal (ρ = 0.933, rRMSE = 12.4%) GRF&M components and as strong for the lateral (ρ = 0.862, rRMSE = 13.1%), frontal (ρ = 0.710, rRMSE = 29.6%), and transverse GRF&M (ρ = 0.826, rRMSE = 18.2%). Sensitivity analysis was performed on the effect of the cut-off frequency used in the filtering of the input kinematics, as well as the threshold velocities for the gait event detection algorithm. This study was the first to use only inertial motion capture to estimate 3D GRF&M during gait, providing comparable accuracy with optical motion capture prediction. This approach enables applications that require estimation of the kinetics during walking outside the gait laboratory. Full article

(This article belongs to the Special Issue Body Worn Behavior Sensing)

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15 pages, 3875 KiB

Open AccessArticle

Evaluating the More Suitable ISM Frequency Band for IoT-Based Smart Grids: A Quantitative Study of 915 MHz vs. 2400 MHz

by Ruben M. Sandoval

, Antonio-Javier Garcia-Sanchez^*, Felipe Garcia-Sanchez and Joan Garcia-Haro

Department of Information and Communication Technologies, Universidad Politécnica de Cartagena (UPCT), Campus Muralla del Mar, E-30202 Cartagena, Spain

Sensors 2017, 17(1), 76; https://doi.org/10.3390/s17010076 - 31 Dec 2016

Cited by 22 | Viewed by 6766

Abstract

IoT has begun to be employed pervasively in industrial environments and critical infrastructures thanks to its positive impact on performance and efficiency. Among these environments, the Smart Grid (SG) excels as the perfect host for this technology, mainly due to its potential to [...] Read more.

IoT has begun to be employed pervasively in industrial environments and critical infrastructures thanks to its positive impact on performance and efficiency. Among these environments, the Smart Grid (SG) excels as the perfect host for this technology, mainly due to its potential to become the motor of the rest of electrically-dependent infrastructures. To make this SG-oriented IoT cost-effective, most deployments employ unlicensed ISM bands, specifically the 2400 MHz one, due to its extended communication bandwidth in comparison with lower bands. This band has been extensively used for years by Wireless Sensor Networks (WSN) and Mobile Ad-hoc Networks (MANET), from which the IoT technologically inherits. However, this work questions and evaluates the suitability of such a “default” communication band in SG environments, compared with the 915 MHz ISM band. A comprehensive quantitative comparison of these bands has been accomplished in terms of: power consumption, average network delay, and packet reception rate. To allow such a study, a dual-band propagation model specifically designed for the SG has been derived, tested, and incorporated into the well-known TOSSIM simulator. Simulation results reveal that only in the absence of other 2400 MHz interfering devices (such as WiFi or Bluetooth) or in small networks, is the 2400 MHz band the best option. In any other case, SG-oriented IoT quantitatively perform better if operating in the 915 MHz band. Full article

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

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13 pages, 5858 KiB

Open AccessArticle

A 3D Faraday Shield for Interdigitated Dielectrometry Sensors and Its Effect on Capacitance

by Alex Risos^1,2,*, Nicholas Long²

, Arvid Hunze² and Gideon Gouws³

¹ School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6012, New Zealand

² Robinson Research Institute, Victoria University of Wellington, Lower Hutt 5010, New Zealand

³ School of Engineering and Computer Sciences, Victoria University of Wellington, Wellington 6012, New Zealand

Sensors 2017, 17(1), 77; https://doi.org/10.3390/s17010077 - 31 Dec 2016

Cited by 13 | Viewed by 7887

Abstract

Interdigitated dielectrometry sensors (IDS) are capacitive sensors investigated to precisely measure the relative permittivity (

ϵ_{r}

) of insulating liquids. Such liquids used in the power industry exhibit a change in

ϵ_{r}

as they degrade. The IDS ability to measure [...] Read more.

Interdigitated dielectrometry sensors (IDS) are capacitive sensors investigated to precisely measure the relative permittivity (

ϵ_{r}

) of insulating liquids. Such liquids used in the power industry exhibit a change in

ϵ_{r}

as they degrade. The IDS ability to measure

ϵ_{r}

in-situ can potentially reduce maintenance, increase grid stability and improve safety. Noise from external electric field sources is a prominent issue with IDS. This paper investigates the novelty of applying a Faraday cage onto an IDS as a 3D shield to reduce this noise. This alters the spatially distributed electric field of an IDS affecting its sensing properties. Therefore, dependency of the sensor’s signal with the distance to a shield above the IDS electrodes has been investigated experimentally and theoretically via a Green’s function calculation and FEM. A criteria of the shield’s distance s =

s_{0}

has been defined as the distance which gives a capacitance for the IDS equal to

1 - e^{- 2} = 86.5 %

of its unshielded value. Theoretical calculations using a simplified geometry gave a constant value for

s_{0}

/

λ

= 1.65, where

λ

is the IDS wavelength. In the experiment, values for

s_{0}

were found to be lower than predicted as from theory and the ratio

s_{0}

/

λ

variable. This was analyzed in detail and it was found to be resulting from the specific spatial structure of the IDS. A subsequent measurement of a common insulating liquid with a nearby noise source demonstrates a considerable reduction in the standard deviation of the relative permittivity from

σ_{unshielded} = \pm

9.5% to

σ_{shielded} = \pm

0.6%. The presented findings enhance our understanding of IDS in respect to the influence of a Faraday shield on the capacitance, parasitic capacitances of the IDS and external noise impact on the measurement of

ϵ_{r}

. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 4961 KiB

Open AccessArticle

Tag-to-Tag Interference Suppression Technique Based on Time Division for RFID

by Grishma Khadka¹

and Suk-Seung Hwang^2,*

¹ Department of Advanced Parts and Material Engineering, Chosun University, Gwangju 501-759, Korea

² Department of Electronic Engineering, Chosun University, Gwangju 501-759, Korea

Sensors 2017, 17(1), 78; https://doi.org/10.3390/s17010078 - 1 Jan 2017

Cited by 16 | Viewed by 5707

Abstract

Radio-frequency identification (RFID) is a tracking technology that enables immediate automatic object identification and rapid data sharing for a wide variety of modern applications using radio waves for data transmission from a tag to a reader. RFID is already well established in technical [...] Read more.

Radio-frequency identification (RFID) is a tracking technology that enables immediate automatic object identification and rapid data sharing for a wide variety of modern applications using radio waves for data transmission from a tag to a reader. RFID is already well established in technical areas, and many companies have developed corresponding standards and measurement techniques. In the construction industry, effective monitoring of materials and equipment is an important task, and RFID helps to improve monitoring and controlling capabilities, in addition to enabling automation for construction projects. However, on construction sites, there are many tagged objects and multiple RFID tags that may interfere with each other’s communications. This reduces the reliability and efficiency of the RFID system. In this paper, we propose an anti-collision algorithm for communication between multiple tags and a reader. In order to suppress interference signals from multiple neighboring tags, the proposed algorithm employs the time-division (TD) technique, where tags in the interrogation zone are assigned a specific time slot so that at every instance in time, a reader communicates with tags using the specific time slot. We present representative computer simulation examples to illustrate the performance of the proposed anti-collision technique for multiple RFID tags. Full article

(This article belongs to the Section Sensor Networks)

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17 pages, 898 KiB

Open AccessArticle

A Truthful Incentive Mechanism for Online Recruitment in Mobile Crowd Sensing System

by Xiao Chen^1,2

, Min Liu^1,*, Yaqin Zhou³, Zhongcheng Li¹, Shuang Chen^1,2 and Xiangnan He^4,*

¹ Institute of Computing Technology, Chinese Academy of Sciences, No. 6 Kexueyuan South Road, Haidian District, Beijing 100190, China

² School of Computer and Control Engineering, University of Chinese Academy of Sciences, No. 19 A Yuquan Road, Shijingshan District, Beijing 100049, China

³ Source Clear, 20 Ayer Rajah Crescent, Singapore 139964, Singapore

⁴ School of Computing, National University of Singapore, Computing 1, Computing Drive, Singapore 117417, Singapore

Sensors 2017, 17(1), 79; https://doi.org/10.3390/s17010079 - 1 Jan 2017

Cited by 19 | Viewed by 5901

Abstract

We investigate emerging mobile crowd sensing (MCS) systems, in which new cloud-based platforms sequentially allocate homogenous sensing jobs to dynamically-arriving users with uncertain service qualities. Given that human beings are selfish in nature, it is crucial yet challenging to design an efficient and [...] Read more.

We investigate emerging mobile crowd sensing (MCS) systems, in which new cloud-based platforms sequentially allocate homogenous sensing jobs to dynamically-arriving users with uncertain service qualities. Given that human beings are selfish in nature, it is crucial yet challenging to design an efficient and truthful incentive mechanism to encourage users to participate. To address the challenge, we propose a novel truthful online auction mechanism that can efficiently learn to make irreversible online decisions on winner selections for new MCS systems without requiring previous knowledge of users. Moreover, we theoretically prove that our incentive possesses truthfulness, individual rationality and computational efficiency. Extensive simulation results under both real and synthetic traces demonstrate that our incentive mechanism can reduce the payment of the platform, increase the utility of the platform and social welfare. Full article

(This article belongs to the Special Issue Advanced Algorithms for Mobile Sensing: from Wireless Sensor Networks to Mobile Crowd Sensing)

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8 pages, 2243 KiB

Open AccessArticle

High Sensitivity Detection of CdSe/ZnS Quantum Dot-Labeled DNA Based on N-type Porous Silicon Microcavities

by Changwu Lv¹, Zhenhong Jia^2,*, Jie Lv³, Hongyan Zhang¹ and Yanyu Li¹

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

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

³ College of Resource and Environment sciences, Xinjiang University, Urumqi 830046, China

Sensors 2017, 17(1), 80; https://doi.org/10.3390/s17010080 - 1 Jan 2017

Cited by 15 | Viewed by 5060

Abstract

N-type macroporous silicon microcavity structures were prepared using electrochemical etching in an HF solution in the absence of light and oxidants. The CdSe/ZnS water-soluble quantum dot-labeled DNA target molecules were detected by monitoring the microcavity reflectance spectrum, which was characterized by the reflectance [...] Read more.

N-type macroporous silicon microcavity structures were prepared using electrochemical etching in an HF solution in the absence of light and oxidants. The CdSe/ZnS water-soluble quantum dot-labeled DNA target molecules were detected by monitoring the microcavity reflectance spectrum, which was characterized by the reflectance spectrum defect state position shift resulting from changes to the structures’ refractive index. Quantum dots with a high refractive index and DNA coupling can improve the detection sensitivity by amplifying the optical response signals of the target DNA. The experimental results show that DNA combined with a quantum dot can improve the sensitivity of DNA detection by more than five times. Full article

(This article belongs to the Section Biosensors)

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15 pages, 22527 KiB

Open AccessArticle

Performance Evaluation of Machine Learning Methods for Leaf Area Index Retrieval from Time-Series MODIS Reflectance Data

by Tongtong Wang

, Zhiqiang Xiao^* and Zhigang Liu

State Key Laboratory of Remote Sensing Science, Beijing Normal University, Beijing 100875, China

Sensors 2017, 17(1), 81; https://doi.org/10.3390/s17010081 - 1 Jan 2017

Cited by 25 | Viewed by 5597

Abstract

Leaf area index (LAI) is an important biophysical parameter and the retrieval of LAI from remote sensing data is the only feasible method for generating LAI products at regional and global scales. However, most LAI retrieval methods use satellite observations at a specific [...] Read more.

Leaf area index (LAI) is an important biophysical parameter and the retrieval of LAI from remote sensing data is the only feasible method for generating LAI products at regional and global scales. However, most LAI retrieval methods use satellite observations at a specific time to retrieve LAI. Because of the impacts of clouds and aerosols, the LAI products generated by these methods are spatially incomplete and temporally discontinuous, and thus they cannot meet the needs of practical applications. To generate high-quality LAI products, four machine learning algorithms, including back-propagation neutral network (BPNN), radial basis function networks (RBFNs), general regression neutral networks (GRNNs), and multi-output support vector regression (MSVR) are proposed to retrieve LAI from time-series Moderate Resolution Imaging Spectroradiometer (MODIS) reflectance data in this study and performance of these machine learning algorithms is evaluated. The results demonstrated that GRNNs, RBFNs, and MSVR exhibited low sensitivity to training sample size, whereas BPNN had high sensitivity. The four algorithms performed slightly better with red, near infrared (NIR), and short wave infrared (SWIR) bands than red and NIR bands, and the results were significantly better than those obtained using single band reflectance data (red or NIR). Regardless of band composition, GRNNs performed better than the other three methods. Among the four algorithms, BPNN required the least training time, whereas MSVR needed the most for any sample size. Full article

(This article belongs to the Section Remote Sensors)

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20 pages, 4668 KiB

Open AccessArticle

Hyperspectral Imagery Super-Resolution by Adaptive POCS and Blur Metric

by Shaoxing Hu^1,*, Shuyu Zhang¹, Aiwu Zhang² and Shatuo Chai³

¹ School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China

² Ministry of Education Key Laboratory of 3D Information Acquisition and Application, Capital Normal University, Beijing 100048, China

³ Qinghai Academy of Animal Science and Veterinary Medicine, Qinghai 810016, China

Sensors 2017, 17(1), 82; https://doi.org/10.3390/s17010082 - 3 Jan 2017

Cited by 7 | Viewed by 4987

Abstract

The spatial resolution of a hyperspectral image is often coarse as the limitations on the imaging hardware. A novel super-resolution reconstruction algorithm for hyperspectral imagery (HSI) via adaptive projection onto convex sets and image blur metric (APOCS-BM) is proposed in this paper to [...] Read more.

The spatial resolution of a hyperspectral image is often coarse as the limitations on the imaging hardware. A novel super-resolution reconstruction algorithm for hyperspectral imagery (HSI) via adaptive projection onto convex sets and image blur metric (APOCS-BM) is proposed in this paper to solve these problems. Firstly, a no-reference image blur metric assessment method based on Gabor wavelet transform is utilized to obtain the blur metric of the low-resolution (LR) image. Then, the bound used in the APOCS is automatically calculated via LR image blur metric. Finally, the high-resolution (HR) image is reconstructed by the APOCS method. With the contribution of APOCS and image blur metric, the fixed bound problem in POCS is solved, and the image blur information is utilized during the reconstruction of HR image, which effectively enhances the spatial-spectral information and improves the reconstruction accuracy. The experimental results for the PaviaU, PaviaC and Jinyin Tan datasets indicate that the proposed method not only enhances the spatial resolution, but also preserves HSI spectral information well. Full article

(This article belongs to the Special Issue Multi-Sensor Integration and Fusion)

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13 pages, 2822 KiB

Open AccessArticle

Satellite Jitter Estimation and Validation Using Parallax Images

by Jun Pan^1,2

, Chengbang Che¹, Ying Zhu¹

and Mi Wang^1,2,*

¹ The State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, 129 Luoyu Road, Wuhan 430079, China

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

Sensors 2017, 17(1), 83; https://doi.org/10.3390/s17010083 - 2 Jan 2017

Cited by 37 | Viewed by 5054

Abstract

Satellite jitter (SJ) is an important error source that affects the geometric accuracy of high resolution satellite imagery. In this paper, the quantitative relationship between the jitter displacement (image displacement caused by SJ) and relative registration error obtained from parallax images is deduced [...] Read more.

Satellite jitter (SJ) is an important error source that affects the geometric accuracy of high resolution satellite imagery. In this paper, the quantitative relationship between the jitter displacement (image displacement caused by SJ) and relative registration error obtained from parallax images is deduced to be theoretical in detail, and the jitter displacement estimation model is built to estimate the jitter displacement. Then, a simulation experiment is carried out to validate the feasibility of using the built jitter displacement estimation model to estimate the jitter displacement. Finally, experiments with real images in DengFeng (China) including multispectral images of Ziyuan-3 (ZY-3) satellite and high resolution (HR) images of Ziyuan1-02C (ZY1-02C) satellite are used to validate the effectiveness of utilizing the built jitter displacement estimation model to do the jitter estimation. High accuracy ground reference data are further used to evaluate the accuracy of the estimation. Experimental results show that the average estimated error for jitter displacement of ZY-3 is 2.96% and 0.11% in amplitude and frequency respectively, and the estimated error for jitter displacement of ZY1-02C is 8.46% and 0.35% in amplitude and frequency, respectively. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 3879 KiB

Open AccessArticle

COSMO-SkyMed Image Investigation of Snow Features in Alpine Environment

by Simonetta Paloscia^1,*

, Simone Pettinato¹

, Emanuele Santi¹

and Mauro Valt²

¹ Institute of Applied Physics, National Research Council, CNR-IFAC, Firenze 50019, Italy

² Avalanche Center of Arabba, Environmental Protection Agency of Veneto, CVA-ARPAV, Arabba 32020, Italy

Sensors 2017, 17(1), 84; https://doi.org/10.3390/s17010084 - 4 Jan 2017

Cited by 13 | Viewed by 5094

Abstract

In this work, X band images acquired by COSMO-SkyMed (CSK) on alpine environment have been analyzed for investigating snow characteristics and their effect on backscattering variations. Preliminary results confirmed the capability of simultaneous optical and Synthetic Aperture Radar (SAR) images (Landsat-8 and CSK) [...] Read more.

In this work, X band images acquired by COSMO-SkyMed (CSK) on alpine environment have been analyzed for investigating snow characteristics and their effect on backscattering variations. Preliminary results confirmed the capability of simultaneous optical and Synthetic Aperture Radar (SAR) images (Landsat-8 and CSK) in separating snow/no-snow areas and in detecting wet snow. The sensitivity of backscattering to snow depth has not always been confirmed, depending on snow characteristics related to the season. A model based on Dense Media Radiative Transfer theory (DMRT-QMS) was applied for simulating the backscattering response on the X band from snow cover in different conditions of grain size, snow density and depth. By using DMRT-QMS and snow in-situ data collected on Cordevole basin in Italian Alps, the effect of grain size and snow density, beside snow depth and snow water equivalent, was pointed out, showing that the snow features affect the backscatter in different and sometimes opposite ways. Experimental values of backscattering were correctly simulated by using this model and selected intervals of ground parameters. The relationship between simulated and measured backscattering for the entire dataset shows slope >0.9, determination coefficient, R² = 0.77, and root mean square error, RMSE = 1.1 dB, with p-value <0.05. Full article

(This article belongs to the Special Issue Synthetic Aperture Radars: Models, Algorithms, Techniques and Tools for Data Exploitation)

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13 pages, 6502 KiB

Open AccessArticle

Analysis of the Light Propagation Model of the Optical Voltage Sensor for Suppressing Unreciprocal Errors

by Hui Li^1,*, Zhida Fu¹, Liying Liu¹, Zhili Lin², Wei Deng¹ and Lishuang Feng¹

¹ Key Laboratory of Precision Opto-mechatronics Technology, Ministry of Education, School of Instrumentation Science and Opto-electronics Engineering, Beihang University, Beijing 100191, China

² Fujian Key Laboratory of Light Propagation and Transformation, College of Information Science and Engineering, Huaqiao University, Xiamen 361021, China

Sensors 2017, 17(1), 85; https://doi.org/10.3390/s17010085 - 3 Jan 2017

Cited by 8 | Viewed by 4807

Abstract

An improved temperature-insensitive optical voltage sensor (OVS) with a reciprocal dual-crystal sensing method is proposed. The inducing principle of OVS reciprocity degradation is expounded by taking the different temperature fields of two crystals and the axis-errors of optical components into consideration. The key [...] Read more.

An improved temperature-insensitive optical voltage sensor (OVS) with a reciprocal dual-crystal sensing method is proposed. The inducing principle of OVS reciprocity degradation is expounded by taking the different temperature fields of two crystals and the axis-errors of optical components into consideration. The key parameters pertaining to the system reciprocity degeneration in the dual-crystal sensing unit are investigated in order to optimize the optical sensing model based on the Maxwell's electromagnetic theory. The influencing principle of axis-angle errors on the system nonlinearity in the Pockels phase transfer unit is analyzed. Moreover, a novel axis-angle compensation method is proposed to improve the OVS measurement precision according to the simulation results. The experiment results show that the measurement precision of OVS is superior to ±0.2% in the temperature range from −40 °C to +60 °C, which demonstrates the excellent temperature stability of the designed voltage sensing system. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 6301 KiB

Open AccessArticle

An Improved Approach for Estimating Daily Net Radiation over the Heihe River Basin

by Bingfang Wu^*

, Shufu Liu, Weiwei Zhu, Nana Yan, Qiang Xing and Shen Tan

Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Sciences, Beijing 100094, China

Sensors 2017, 17(1), 86; https://doi.org/10.3390/s17010086 - 4 Jan 2017

Cited by 35 | Viewed by 5102

Abstract

Net radiation plays an essential role in determining the thermal conditions of the Earth’s surface and is an important parameter for the study of land-surface processes and global climate change. In this paper, an improved satellite-based approach to estimate the daily net radiation [...] Read more.

Net radiation plays an essential role in determining the thermal conditions of the Earth’s surface and is an important parameter for the study of land-surface processes and global climate change. In this paper, an improved satellite-based approach to estimate the daily net radiation is presented, in which sunshine duration were derived from the geostationary meteorological satellite (FY-2D) cloud classification product, the monthly empirical a_s and b_s Angstrom coefficients for net shortwave radiation were calibrated by spatial fitting of the ground data from 1997 to 2006, and the daily net longwave radiation was calibrated with ground data from 2007 to 2010 over the Heihe River Basin in China. The estimated daily net radiation values were validated against ground data for 12 months in 2008 at four stations with different underlying surface types. The average coefficient of determination (R²) was 0.8489, and the averaged Nash-Sutcliffe equation (NSE) was 0.8356. The close agreement between the estimated daily net radiation and observations indicates that the proposed method is promising, especially given the comparison between the spatial distribution and the interpolation of sunshine duration. Potential applications include climate research, energy balance studies and the estimation of global evapotranspiration. Full article

(This article belongs to the Section Remote Sensors)

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13 pages, 6128 KiB

Open AccessArticle

An Integrated Microfabricated Chip with Double Functions as an Ion Source and Air Pump Based on LIGA Technology

by Hua Li^1,2,*

, Linxiu Jiang¹, Chaoqun Guo¹, Jianmin Zhu¹, Yongrong Jiang¹ and Zhencheng Chen^1,*

¹ School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541004, China

² Guangxi Experiment Center of Information Science, Guilin 541004, China

Sensors 2017, 17(1), 87; https://doi.org/10.3390/s17010087 - 4 Jan 2017

Cited by 3 | Viewed by 5017

Abstract

The injection and ionization of volatile organic compounds (VOA) by an integrated chip is experimentally analyzed in this paper. The integrated chip consists of a needle-to-cylinder electrode mounting on the Polymethyl Methacrylate (PMMA) substrate. The needle-to-cylinder electrode is designed and fabricated by Lithographie, [...] Read more.

The injection and ionization of volatile organic compounds (VOA) by an integrated chip is experimentally analyzed in this paper. The integrated chip consists of a needle-to-cylinder electrode mounting on the Polymethyl Methacrylate (PMMA) substrate. The needle-to-cylinder electrode is designed and fabricated by Lithographie, Galvanoformung and Abformung (LIGA) technology. In this paper, the needle is connected to a negative power supply of −5 kV and used as the cathode; the cylinder electrodes are composed of two arrays of cylinders and serve as the anode. The ionic wind is produced based on corona and glow discharges of needle-to-cylinder electrodes. The experimental setup is designed to observe the properties of the needle-to-cylinder discharge and prove its functions as an ion source and air pump. In summary, the main results are as follows: (1) the ionic wind velocity produced by the chip is about 0.79 m/s at an applied voltage of −3300 V; (2) acetic acid and ammonia water can be injected through the chip, which is proved by pH test paper; and (3) the current measured by a Faraday cup is about 10 pA for acetic acid and ammonia with an applied voltage of −3185 V. The integrated chip is promising for portable analytical instruments, such as ion mobility spectrometry (IMS), field asymmetric ion mobility spectrometry (FAIMS), and mass spectrometry (MS). Full article

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

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17 pages, 4479 KiB

Open AccessArticle

Enhance the Quality of Crowdsensing for Fine-Grained Urban Environment Monitoring via Data Correlation

by Xu Kang, Liang Liu^* and Huadong Ma

Beijing Key Laboratory of Intelligent Telecommunications Software and Multimedia, Beijing University of Posts and Telecommunications, Beijing 100876, China

Sensors 2017, 17(1), 88; https://doi.org/10.3390/s17010088 - 4 Jan 2017

Cited by 12 | Viewed by 5440

Abstract

Monitoring the status of urban environments, which provides fundamental information for a city, yields crucial insights into various fields of urban research. Recently, with the popularity of smartphones and vehicles equipped with onboard sensors, a people-centric scheme, namely “crowdsensing”, for city-scale environment monitoring [...] Read more.

Monitoring the status of urban environments, which provides fundamental information for a city, yields crucial insights into various fields of urban research. Recently, with the popularity of smartphones and vehicles equipped with onboard sensors, a people-centric scheme, namely “crowdsensing”, for city-scale environment monitoring is emerging. This paper proposes a data correlation based crowdsensing approach for fine-grained urban environment monitoring. To demonstrate urban status, we generate sensing images via crowdsensing network, and then enhance the quality of sensing images via data correlation. Specifically, to achieve a higher quality of sensing images, we not only utilize temporal correlation of mobile sensing nodes but also fuse the sensory data with correlated environment data by introducing a collective tensor decomposition approach. Finally, we conduct a series of numerical simulations and a real dataset based case study. The results validate that our approach outperforms the traditional spatial interpolation-based method. Full article

(This article belongs to the Special Issue New Paradigms in Cyber-Physical Social Sensing)

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30 pages, 27840 KiB

Open AccessArticle

Assessment of Pansharpening Methods Applied to WorldView-2 Imagery Fusion

by Hui Li^*

, Linhai Jing^* and Yunwei Tang

Key Laborary of Digital Earth Sciences, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China

Sensors 2017, 17(1), 89; https://doi.org/10.3390/s17010089 - 5 Jan 2017

Cited by 43 | Viewed by 6767

Abstract

Since WorldView-2 (WV-2) images are widely used in various fields, there is a high demand for the use of high-quality pansharpened WV-2 images for different application purposes. With respect to the novelty of the WV-2 multispectral (MS) and panchromatic (PAN) bands, the performances [...] Read more.

Since WorldView-2 (WV-2) images are widely used in various fields, there is a high demand for the use of high-quality pansharpened WV-2 images for different application purposes. With respect to the novelty of the WV-2 multispectral (MS) and panchromatic (PAN) bands, the performances of eight state-of-art pan-sharpening methods for WV-2 imagery including six datasets from three WV-2 scenes were assessed in this study using both quality indices and information indices, along with visual inspection. The normalized difference vegetation index, normalized difference water index, and morphological building index, which are widely used in applications related to land cover classification, the extraction of vegetation areas, buildings, and water bodies, were employed in this work to evaluate the performance of different pansharpening methods in terms of information presentation ability. The experimental results show that the Haze- and Ratio-based, adaptive Gram-Schmidt, Generalized Laplacian pyramids (GLP) methods using enhanced spectral distortion minimal model and enhanced context-based decision model methods are good choices for producing fused WV-2 images used for image interpretation and the extraction of urban buildings. The two GLP-based methods are better choices than the other methods, if the fused images will be used for applications related to vegetation and water-bodies. Full article

(This article belongs to the Section Remote Sensors)

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9 pages, 2058 KiB

Open AccessArticle

Wavelength-Scanning SPR Imaging Sensors Based on an Acousto-Optic Tunable Filter and a White Light Laser

by Youjun Zeng¹, Lei Wang¹, Shu-Yuen Wu², Jianan He³, Junle Qu¹, Xuejin Li¹, Ho-Pui Ho², Dayong Gu³, Bruce Zhi Gao⁴ and Yonghong Shao^1,*

¹ College of Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen Key Laboratory of Sensor Technology, Shenzhen University, Shenzhen 518060, China

² Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin 999077, Hong Kong, China

³ Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen 518033, China

⁴ Department of Bioengineering and COMSET, Clemson University, Clemson, SC 29634, USA

Sensors 2017, 17(1), 90; https://doi.org/10.3390/s17010090 - 5 Jan 2017

Cited by 33 | Viewed by 8506

Abstract

A fast surface plasmon resonance (SPR) imaging biosensor system based on wavelength interrogation using an acousto-optic tunable filter (AOTF) and a white light laser is presented. The system combines the merits of a wide-dynamic detection range and high sensitivity offered by the spectral [...] Read more.

A fast surface plasmon resonance (SPR) imaging biosensor system based on wavelength interrogation using an acousto-optic tunable filter (AOTF) and a white light laser is presented. The system combines the merits of a wide-dynamic detection range and high sensitivity offered by the spectral approach with multiplexed high-throughput data collection and a two-dimensional (2D) biosensor array. The key feature is the use of AOTF to realize wavelength scan from a white laser source and thus to achieve fast tracking of the SPR dip movement caused by target molecules binding to the sensor surface. Experimental results show that the system is capable of completing a SPR dip measurement within 0.35 s. To the best of our knowledge, this is the fastest time ever reported in the literature for imaging spectral interrogation. Based on a spectral window with a width of approximately 100 nm, a dynamic detection range and resolution of 4.63 × 10⁻² refractive index unit (RIU) and 1.27 × 10⁻⁶ RIU achieved in a 2D-array sensor is reported here. The spectral SPR imaging sensor scheme has the capability of performing fast high-throughput detection of biomolecular interactions from 2D sensor arrays. The design has no mechanical moving parts, thus making the scheme completely solid-state. Full article

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

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13 pages, 511 KiB

Open AccessArticle

High Resolution Temperature Measurement of Liquid Stainless Steel Using Hyperspectral Imaging

by Wim Devesse^*

, Dieter De Baere and Patrick Guillaume

Vrije Universiteit Brussel, Department of Mechanical Engineering, Pleinlaan 2, B-1050 Brussels, Belgium

Sensors 2017, 17(1), 91; https://doi.org/10.3390/s17010091 - 5 Jan 2017

Cited by 39 | Viewed by 7101

Abstract

A contactless temperature measurement system is presented based on a hyperspectral line camera that captures the spectra in the visible and near infrared (VNIR) region of a large set of closely spaced points. The measured spectra are used in a nonlinear least squares [...] Read more.

A contactless temperature measurement system is presented based on a hyperspectral line camera that captures the spectra in the visible and near infrared (VNIR) region of a large set of closely spaced points. The measured spectra are used in a nonlinear least squares optimization routine to calculate a one-dimensional temperature profile with high spatial resolution. Measurements of a liquid melt pool of AISI 316L stainless steel show that the system is able to determine the absolute temperatures with an accuracy of 10%. The measurements are made with a spatial resolution of 12 µm/pixel, justifying its use in applications where high temperature measurements with high spatial detail are desired, such as in the laser material processing and additive manufacturing fields. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 5045 KiB

Open AccessArticle

Depth Errors Analysis and Correction for Time-of-Flight (ToF) Cameras

by Ying He^1,*, Bin Liang^1,2

, Yu Zou², Jin He² and Jun Yang³

¹ Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055, China

² Department of Automation, Tsinghua University, Beijing 100084, China

³ Shenzhen Graduate School, Tsinghua University, Shenzhen 518055, China

Sensors 2017, 17(1), 92; https://doi.org/10.3390/s17010092 - 5 Jan 2017

Cited by 78 | Viewed by 11986

Abstract

Time-of-Flight (ToF) cameras, a technology which has developed rapidly in recent years, are 3D imaging sensors providing a depth image as well as an amplitude image with a high frame rate. As a ToF camera is limited by the imaging conditions and external [...] Read more.

Time-of-Flight (ToF) cameras, a technology which has developed rapidly in recent years, are 3D imaging sensors providing a depth image as well as an amplitude image with a high frame rate. As a ToF camera is limited by the imaging conditions and external environment, its captured data are always subject to certain errors. This paper analyzes the influence of typical external distractions including material, color, distance, lighting, etc. on the depth error of ToF cameras. Our experiments indicated that factors such as lighting, color, material, and distance could cause different influences on the depth error of ToF cameras. However, since the forms of errors are uncertain, it’s difficult to summarize them in a unified law. To further improve the measurement accuracy, this paper proposes an error correction method based on Particle Filter-Support Vector Machine (PF-SVM). Moreover, the experiment results showed that this method can effectively reduce the depth error of ToF cameras to 4.6 mm within its full measurement range (0.5–5 m). Full article

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

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19 pages, 1249 KiB

Open AccessArticle

A Fuzzy-Based Approach for Sensing, Coding and Transmission Configuration of Visual Sensors in Smart City Applications

by Daniel G. Costa^1,*,†

, Mario Collotta^2,†

, Giovanni Pau^2,†

and Cristian Duran-Faundez^3,†

¹ Department of Technology, State University of Feira de Santana, Feira de Santana 44036-900, Brazil

² Faculty of Engineering and Architecture, Kore University of Enna, Enna 94100, Italy

³ Department of Electrical and Electronic Engineering, University of the Bío-Bío, Bío Bío Region 4051381, Chile

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 93; https://doi.org/10.3390/s17010093 - 5 Jan 2017

Cited by 37 | Viewed by 6476

Abstract

The advance of technologies in several areas has allowed the development of smart city applications, which can improve the way of life in modern cities. When employing visual sensors in that scenario, still images and video streams may be retrieved from monitored areas, [...] Read more.

The advance of technologies in several areas has allowed the development of smart city applications, which can improve the way of life in modern cities. When employing visual sensors in that scenario, still images and video streams may be retrieved from monitored areas, potentially providing valuable data for many applications. Actually, visual sensor networks may need to be highly dynamic, reflecting the changing of parameters in smart cities. In this context, characteristics of visual sensors and conditions of the monitored environment, as well as the status of other concurrent monitoring systems, may affect how visual sensors collect, encode and transmit information. This paper proposes a fuzzy-based approach to dynamically configure the way visual sensors will operate concerning sensing, coding and transmission patterns, exploiting different types of reference parameters. This innovative approach can be considered as the basis for multi-systems smart city applications based on visual monitoring, potentially bringing significant results for this research field. Full article

(This article belongs to the Section Sensor Networks)

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23 pages, 12584 KiB

Open AccessArticle

Easy Handling of Sensors and Actuators over TCP/IP Networks by Open Source Hardware/Software

by Andrés Mejías^1,*, Reyes S. Herrera², Marco A. Márquez³, Antonio José Calderón⁴

, Isaías González⁴

and José Manuel Andújar¹

¹ Department of Electronic, Computer Science and Automation Engineering, University of Huelva, Escuela Técnica Superior de Ingeniería, Ctra. Huelva-Palos de la Fra, 21819 Huelva, Spain

² Department of Electrical Engineering, University of Huelva, Escuela Técnica Superior de Ingeniería, Ctra. Huelva-Palos de la Fra, 21819 Huelva, Spain

³ Control and Robotics Research Group, University of Huelva, Escuela Técnica Superior de Ingeniería, Ctra. Huelva-Palos de la Fra, 21819 Huelva, Spain

⁴ Department of Electrical Engineering, Electronics and Automation, University of Extremadura, Avenida de Elvas, s/n, 06006 Badajoz, Spain

Sensors 2017, 17(1), 94; https://doi.org/10.3390/s17010094 - 5 Jan 2017

Cited by 47 | Viewed by 11141

Abstract

There are several specific solutions for accessing sensors and actuators present in any process or system through a TCP/IP network, either local or a wide area type like the Internet. The usage of sensors and actuators of different nature and diverse interfaces (SPI, [...] Read more.

There are several specific solutions for accessing sensors and actuators present in any process or system through a TCP/IP network, either local or a wide area type like the Internet. The usage of sensors and actuators of different nature and diverse interfaces (SPI, I2C, analogue, etc.) makes access to them from a network in a homogeneous and secure way more complex. A framework, including both software and hardware resources, is necessary to simplify and unify networked access to these devices. In this paper, a set of open-source software tools, specifically designed to cover the different issues concerning the access to sensors and actuators, and two proposed low-cost hardware architectures to operate with the abovementioned software tools are presented. They allow integrated and easy access to local or remote sensors and actuators. The software tools, integrated in the free authoring tool Easy Java and Javascript Simulations (EJS) solve the interaction issues between the subsystem that integrates sensors and actuators into the network, called convergence subsystem in this paper, and the Human Machine Interface (HMI)—this one designed using the intuitive graphical system of EJS—located on the user’s computer. The proposed hardware architectures and software tools are described and experimental implementations with the proposed tools are presented. Full article

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

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20 pages, 7667 KiB

Open AccessArticle

Air-Coupled Low Frequency Ultrasonic Transducers and Arrays with PMN-32%PT Piezoelectric Crystals

by Rymantas J. Kazys^*, Reimondas Sliteris and Justina Sestoke

Ultrasound Institute, Kaunas University of Technology, Kaunas LT-51423, Lithuania

Sensors 2017, 17(1), 95; https://doi.org/10.3390/s17010095 - 6 Jan 2017

Cited by 20 | Viewed by 9324

Abstract

Air-coupled ultrasonic techniques are being increasingly used for material characterization, non-destructive evaluation of composite materials using guided waves as well as for distance measurements. Application of those techniques is mainly limited by the big losses of ultrasonic signals due to attenuation and mismatch [...] Read more.

Air-coupled ultrasonic techniques are being increasingly used for material characterization, non-destructive evaluation of composite materials using guided waves as well as for distance measurements. Application of those techniques is mainly limited by the big losses of ultrasonic signals due to attenuation and mismatch of the acoustic impedances of ultrasonic transducers and air. One of the ways to solve this problem is by application of novel more efficient piezoelectric materials like lead magnesium niobate-lead titanate (PMN-PT) type crystals. The objective of this research was the development and investigation of low frequency (<50 kHz) wide band air-coupled ultrasonic transducers and arrays with an improved performance using PMN-32%PT crystals. Results of finite element modelling and experimental investigations of the developed transducers and arrays are presented. For improvement of the performance strip-like matching elements made of low acoustic impedance, materials such as polystyrene foams were applied. It allowed to achieve transduction losses for one single element transducer −11.4 dB, what is better than of commercially available air-coupled ultrasonic transducers. Theoretical and experimental investigations of the acoustic fields radiated by the eight element ultrasonic array demonstrated not only a good performance of the array in a pulse mode, but also very good possibilities to electronically focus and steer the ultrasonic beam in space. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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19 pages, 11056 KiB

Open AccessArticle

Multiple Drosophila Tracking System with Heading Direction

by Pudith Sirigrivatanawong^1,*, Shogo Arai², Vladimiros Thoma³ and Koichi Hashimoto¹

¹ Graduate School of Information Sciences, Tohoku University, Aramaki Aza Aoba 6-6-01, Aoba-Ku, Sendai 980-8579, Japan

² Graduate School of Engineering, Tohoku University, Aramaki Aza Aoba 6-6-01, Aoba-Ku, Sendai 980-8579, Japan

³ Graduate School of Life Sciences, Tohoku University, Katahira 2-1-1, Miyagi, Sendai 980-8577, Japan

Sensors 2017, 17(1), 96; https://doi.org/10.3390/s17010096 - 5 Jan 2017

Cited by 6 | Viewed by 6618

Abstract

Machine vision systems have been widely used for image analysis, especially that which is beyond human ability. In biology, studies of behavior help scientists to understand the relationship between sensory stimuli and animal responses. This typically requires the analysis and quantification of animal [...] Read more.

Machine vision systems have been widely used for image analysis, especially that which is beyond human ability. In biology, studies of behavior help scientists to understand the relationship between sensory stimuli and animal responses. This typically requires the analysis and quantification of animal locomotion. In our work, we focus on the analysis of the locomotion of the fruit fly

D r o s o p h i l a

m e l a n o g a s t e r

, a widely used model organism in biological research. Our system consists of two components: fly detection and tracking. Our system provides the ability to extract a group of flies as the objects of concern and furthermore determines the heading direction of each fly. As each fly moves, the system states are refined with a Kalman filter to obtain the optimal estimation. For the tracking step, combining information such as position and heading direction with assignment algorithms gives a successful tracking result. The use of heading direction increases the system efficiency when dealing with identity loss and flies swapping situations. The system can also operate with a variety of videos with different light intensities. Full article

(This article belongs to the Section Physical Sensors)

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8 pages, 2793 KiB

Open AccessArticle

Mixed-Potential Gas Sensors Using an Electrolyte Consisting of Zinc Phosphate Glass and Benzimidazole

by Takafumi Akamatsu^*, Toshio Itoh and Woosuck Shin

National Institute of Advanced Industrial Science and Technology (AIST), Inorganic Functional Materials Research Institute, 2266-98, Anagahora, Shimo-Shidami, Moriyama-ku, Nagoya-shi 463-8560, Japan

Sensors 2017, 17(1), 97; https://doi.org/10.3390/s17010097 - 5 Jan 2017

Cited by 7 | Viewed by 5188

Abstract

Mixed-potential gas sensors with a proton conductor consisting of zinc metaphosphate glass and benzimidazole were fabricated for the detection of hydrogen produced by intestinal bacteria in dry and humid air. The gas sensor consisting of an alumina substrate with platinum and gold electrodes [...] Read more.

Mixed-potential gas sensors with a proton conductor consisting of zinc metaphosphate glass and benzimidazole were fabricated for the detection of hydrogen produced by intestinal bacteria in dry and humid air. The gas sensor consisting of an alumina substrate with platinum and gold electrodes showed good response to different hydrogen concentrations from 250 parts per million (ppm) to 25,000 ppm in dry and humid air at 100–130 °C. The sensor response varied linearly with the hydrogen and carbon monoxide concentrations due to mass transport limitations. The sensor responses to hydrogen gas (e.g., −0.613 mV to 1000 ppm H₂) was higher than those to carbon monoxide gas (e.g., −0.128 mV to 1000 ppm CO) at 120 °C under atmosphere with the same level of humidity as expired air. Full article

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

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18 pages, 5127 KiB

Open AccessArticle

Two-UAV Intersection Localization System Based on the Airborne Optoelectronic Platform

by Guanbing Bai^1,2, Jinghong Liu^1,*, Yueming Song¹ and Yujia Zuo^1,2

¹ Chinese Academy of Science, Changchun Institute of Optics Fine Mechanics and Physics, Key Laboratory of Airborne Optical Imaging and Measurement, #3888 Dongnanhu Road, Changchun 130033, China

² University of Chinese Academy of Sciences, #19 Yuquan Road, Beijing 100049, China

Sensors 2017, 17(1), 98; https://doi.org/10.3390/s17010098 - 6 Jan 2017

Cited by 39 | Viewed by 6960

Abstract

To address the limitation of the existing UAV (unmanned aerial vehicles) photoelectric localization method used for moving objects, this paper proposes an improved two-UAV intersection localization system based on airborne optoelectronic platforms by using the crossed-angle localization method of photoelectric theodolites for reference. [...] Read more.

To address the limitation of the existing UAV (unmanned aerial vehicles) photoelectric localization method used for moving objects, this paper proposes an improved two-UAV intersection localization system based on airborne optoelectronic platforms by using the crossed-angle localization method of photoelectric theodolites for reference. This paper introduces the makeup and operating principle of intersection localization system, creates auxiliary coordinate systems, transforms the LOS (line of sight, from the UAV to the target) vectors into homogeneous coordinates, and establishes a two-UAV intersection localization model. In this paper, the influence of the positional relationship between UAVs and the target on localization accuracy has been studied in detail to obtain an ideal measuring position and the optimal localization position where the optimal intersection angle is 72.6318°. The result shows that, given the optimal position, the localization root mean square error (RMS) will be 25.0235 m when the target is 5 km away from UAV baselines. Finally, the influence of modified adaptive Kalman filtering on localization results is analyzed, and an appropriate filtering model is established to reduce the localization RMS error to 15.7983 m. Finally, An outfield experiment was carried out and obtained the optimal results:

σ_{B} = 1.63 \times 10^{- 4} (°)

,

σ_{L} = 1.35 \times 10^{- 4} (°)

,

σ_{H} = 15.8 (m)

,

σ_{s u m} = 27.6 (m)

, where

σ_{B}

represents the longitude error,

σ_{L}

represents the latitude error,

σ_{H}

represents the altitude error, and

σ_{s u m}

represents the error radius. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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14 pages, 1850 KiB

Open AccessArticle

PHYLIS: A Low-Cost Portable Visible Range Spectrometer for Soil and Plants

by Matt J. Aitkenhead^1,*

, Graham J. Gaskin¹, Noemie Lafouge² and Cathy Hawes¹

¹ The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK

² Ecole d’Ingénieurs de Purpan, 75 Voie du Toec, 31076 Toulouse, France

Sensors 2017, 17(1), 99; https://doi.org/10.3390/s17010099 - 7 Jan 2017

Cited by 14 | Viewed by 7843

Abstract

Monitoring soil and crop condition is vital for the sustainable management of agricultural systems. Often, land management decision-making requires rapid assessment of conditions, which is difficult if samples need to be taken and sent elsewhere for analysis. In recent years, advances in field-based [...] Read more.

Monitoring soil and crop condition is vital for the sustainable management of agricultural systems. Often, land management decision-making requires rapid assessment of conditions, which is difficult if samples need to be taken and sent elsewhere for analysis. In recent years, advances in field-based spectroscopy have led to improvements in real-time monitoring; however, the cost of equipment and user training still makes it inaccessible for most land managers. At the James Hutton Institute, we have developed a low-cost visible wavelength hyperspectral device intended to provide rapid field-based assessment of soil and plant conditions. This device has been tested at the Institute’s research farm at Balruddery, linking field observations with existing sample analysis and crop type information. We show that it is possible to rapidly and easily acquire spectral information that enables site characteristics to be estimated. Improvements to the sensor and its potential uses are discussed. Full article

(This article belongs to the Special Issue Sensors for Environmental Monitoring 2016)

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9 pages, 6286 KiB

Open AccessArticle

Under-Coupling Whispering Gallery Mode Resonator Applied to Resonant Micro-Optic Gyroscope

by Kun Qian

, Jun Tang, Hao Guo, Wenyao Liu, Jun Liu^*, Chenyang Xue, Yongqiu Zheng and Chengfei Zhang

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

Sensors 2017, 17(1), 100; https://doi.org/10.3390/s17010100 - 6 Jan 2017

Cited by 28 | Viewed by 9111

Abstract

As an important sensing element, the whispering gallery mode resonator (WGMR) parameters seriously affect the resonant micro-optic gyroscope (RMOG) performance. This work proposes an under-coupling resonator to improve the resonator’s Q value and to optimize the coupling coefficient to maximize the RMOG’s sensitivity. [...] Read more.

As an important sensing element, the whispering gallery mode resonator (WGMR) parameters seriously affect the resonant micro-optic gyroscope (RMOG) performance. This work proposes an under-coupling resonator to improve the resonator’s Q value and to optimize the coupling coefficient to maximize the RMOG’s sensitivity. GeO₂-doped silica waveguide-type resonators with different coupling coefficients were simulated, designed, fabricated and tested. An under-coupling ring resonator with a quality factor of 10 million is reported. The RMOG system was built based on this resonator and the scale factor was tested on a uniaxial high-precision rotating platform. Experimental results show that this resonator could improve the RMOG sensitivity by five times. Full article

(This article belongs to the Section Physical Sensors)

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27 pages, 12468 KiB

Open AccessArticle

Spectrum Sharing Based on a Bertrand Game in Cognitive Radio Sensor Networks

by Biqing Zeng^1,*, Chi Zhang², Pianpian Hu¹ and Shengyu Wang¹

¹ School of Computing, South China Normal University, Guangzhou 510631, China

² IFLYTEK Co., Ltd., Hefei 230000, China

Sensors 2017, 17(1), 101; https://doi.org/10.3390/s17010101 - 7 Jan 2017

Cited by 11 | Viewed by 5623

Abstract

In the study of power control and allocation based on pricing, the utility of secondary users is usually studied from the perspective of the signal to noise ratio. The study of secondary user utility from the perspective of communication demand can not only [...] Read more.

In the study of power control and allocation based on pricing, the utility of secondary users is usually studied from the perspective of the signal to noise ratio. The study of secondary user utility from the perspective of communication demand can not only promote the secondary users to meet the maximum communication needs, but also to maximize the utilization of spectrum resources, however, research in this area is lacking, so from the viewpoint of meeting the demand of network communication, this paper designs a two stage model to solve spectrum leasing and allocation problem in cognitive radio sensor networks (CRSNs). In the first stage, the secondary base station collects the secondary network communication requirements, and rents spectrum resources from several primary base stations using the Bertrand game to model the transaction behavior of the primary base station and secondary base station. The second stage, the subcarriers and power allocation problem of secondary base stations is defined as a nonlinear programming problem to be solved based on Nash bargaining. The simulation results show that the proposed model can satisfy the communication requirements of each user in a fair and efficient way compared to other spectrum sharing schemes. Full article

(This article belongs to the Special Issue New Paradigms in Cyber-Physical Social Sensing)

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13 pages, 2740 KiB

Open AccessArticle

Iodine Absorption Cells Purity Testing

by Jan Hrabina^1,*

, Massimo Zucco²

, Charles Philippe³, Tuan Minh Pham¹

, Miroslava Holá¹

, Ouali Acef³, Josef Lazar¹ and Ondřej Číp¹

¹ Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Královopolská 147, 61264 Brno, Czech Republic

² National Institute of Metrological Research, Strada delle Cacce 91, 10135 Torino, Italy

³ Sytèmes de Référence Temps Espace, SYRTE/CNRS-UMR 8630/LNE/Observatoire de Paris/UPMC, 61, Avenue de l’Observatoire, 75014 Paris, France

Sensors 2017, 17(1), 102; https://doi.org/10.3390/s17010102 - 6 Jan 2017

Cited by 7 | Viewed by 6276

Abstract

This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods [...] Read more.

This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions’ spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches). Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 19859 KiB

Open AccessArticle

Detection, Location and Grasping Objects Using a Stereo Sensor on UAV in Outdoor Environments

by Pablo Ramon Soria^*, Begoña C. Arrue

and Anibal Ollero

Robotics, Vision and Control Group, University of Seville, Camino de los Descubrimientos, s/n, Seville 41092, Spain

Sensors 2017, 17(1), 103; https://doi.org/10.3390/s17010103 - 7 Jan 2017

Cited by 52 | Viewed by 8932

Abstract

The article presents a vision system for the autonomous grasping of objects with Unmanned Aerial Vehicles (UAVs) in real time. Giving UAVs the capability to manipulate objects vastly extends their applications, as they are capable of accessing places that are difficult to reach [...] Read more.

The article presents a vision system for the autonomous grasping of objects with Unmanned Aerial Vehicles (UAVs) in real time. Giving UAVs the capability to manipulate objects vastly extends their applications, as they are capable of accessing places that are difficult to reach or even unreachable for human beings. This work is focused on the grasping of known objects based on feature models. The system runs in an on-board computer on a UAV equipped with a stereo camera and a robotic arm. The algorithm learns a feature-based model in an offline stage, then it is used online for detection of the targeted object and estimation of its position. This feature-based model was proved to be robust to both occlusions and the presence of outliers. The use of stereo cameras improves the learning stage, providing 3D information and helping to filter features in the online stage. An experimental system was derived using a rotary-wing UAV and a small manipulator for final proof of concept. The robotic arm is designed with three degrees of freedom and is lightweight due to payload limitations of the UAV. The system has been validated with different objects, both indoors and outdoors. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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23 pages, 8873 KiB

Open AccessArticle

3D Visual Tracking of an Articulated Robot in Precision Automated Tasks

by Hamza Alzarok^*, Simon Fletcher and Andrew P. Longstaff

Centre for Precision Technologies, School of Computing and Engineering, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK

Sensors 2017, 17(1), 104; https://doi.org/10.3390/s17010104 - 7 Jan 2017

Cited by 10 | Viewed by 8045

Abstract

The most compelling requirements for visual tracking systems are a high detection accuracy and an adequate processing speed. However, the combination between the two requirements in real world applications is very challenging due to the fact that more accurate tracking tasks often require [...] Read more.

The most compelling requirements for visual tracking systems are a high detection accuracy and an adequate processing speed. However, the combination between the two requirements in real world applications is very challenging due to the fact that more accurate tracking tasks often require longer processing times, while quicker responses for the tracking system are more prone to errors, therefore a trade-off between accuracy and speed, and vice versa is required. This paper aims to achieve the two requirements together by implementing an accurate and time efficient tracking system. In this paper, an eye-to-hand visual system that has the ability to automatically track a moving target is introduced. An enhanced Circular Hough Transform (CHT) is employed for estimating the trajectory of a spherical target in three dimensions, the colour feature of the target was carefully selected by using a new colour selection process, the process relies on the use of a colour segmentation method (Delta E) with the CHT algorithm for finding the proper colour of the tracked target, the target was attached to the six degree of freedom (DOF) robot end-effector that performs a pick-and-place task. A cooperation of two Eye-to Hand cameras with their image Averaging filters are used for obtaining clear and steady images. This paper also examines a new technique for generating and controlling the observation search window in order to increase the computational speed of the tracking system, the techniques is named Controllable Region of interest based on Circular Hough Transform (CRCHT). Moreover, a new mathematical formula is introduced for updating the depth information of the vision system during the object tracking process. For more reliable and accurate tracking, a simplex optimization technique was employed for the calculation of the parameters for camera to robotic transformation matrix. The results obtained show the applicability of the proposed approach to track the moving robot with an overall tracking error of 0.25 mm. Also, the effectiveness of CRCHT technique in saving up to 60% of the overall time required for image processing. Full article

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

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25 pages, 561 KiB

Open AccessArticle

Pruning-Based Sparse Recovery for Electrocardiogram Reconstruction from Compressed Measurements

by Jaeseok Lee, Kyungsoo Kim and Ji-Woong Choi^*

Department of Information & Communication Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 771-813, Korea

Sensors 2017, 17(1), 105; https://doi.org/10.3390/s17010105 - 7 Jan 2017

Cited by 4 | Viewed by 6465

Abstract

Due to the necessity of the low-power implementation of newly-developed electrocardiogram (ECG) sensors, exact ECG data reconstruction from the compressed measurements has received much attention in recent years. Our interest lies in improving the compression ratio (CR), as well as the ECG reconstruction [...] Read more.

Due to the necessity of the low-power implementation of newly-developed electrocardiogram (ECG) sensors, exact ECG data reconstruction from the compressed measurements has received much attention in recent years. Our interest lies in improving the compression ratio (CR), as well as the ECG reconstruction performance of the sparse signal recovery. To this end, we propose a sparse signal reconstruction method by pruning-based tree search, which attempts to choose the globally-optimal solution by minimizing the cost function. In order to achieve low complexity for the real-time implementation, we employ a novel pruning strategy to avoid exhaustive tree search. Through the restricted isometry property (RIP)-based analysis, we show that the exact recovery condition of our approach is more relaxed than any of the existing methods. Through the simulations, we demonstrate that the proposed approach outperforms the existing sparse recovery methods for ECG reconstruction. Full article

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

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18 pages, 5299 KiB

Open AccessArticle

Particle Accumulation in a Microchannel and Its Reduction by a Standing Surface Acoustic Wave (SSAW)

by Yannapol Sriphutkiat and Yufeng Zhou^*

School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Ave., Singapore Centre for 3D Printing (SC3DP), Singapore 639798, Singapore

Sensors 2017, 17(1), 106; https://doi.org/10.3390/s17010106 - 7 Jan 2017

Cited by 23 | Viewed by 7961

Abstract

Accumulation of particles in a high concentration on a microchannel wall is a common phenomenon in a colloidal fluid. Gradual accumulation/deposition of particles can eventually obstruct the fluid flow and lead to clogging, which seriously affects the accuracy and reliability of nozzle-based printing [...] Read more.

Accumulation of particles in a high concentration on a microchannel wall is a common phenomenon in a colloidal fluid. Gradual accumulation/deposition of particles can eventually obstruct the fluid flow and lead to clogging, which seriously affects the accuracy and reliability of nozzle-based printing and causes damage to the nozzle. Particle accumulation in a 100 μm microchannel was investigated by light microscopy, and its area growth in an exponential format was used to quantify this phenomenon. The effects of the constriction angle and alginate concentration on particle accumulation were also studied. In order to reduce the clogging problem, an acoustic method was proposed and evaluated here. Numerical simulation was first conducted to predict the acoustic radiation force on the particles in the fluid with different viscosities. Interdigital transducers (IDTs) were fabricated on the LiNbO₃ wafer to produce standing surface acoustic waves (SSAW) in the microchannel. It was found that the actuation of SSAW can reduce the accumulation area in the microchannel by 2 to 3.7-fold. In summary, the particle accumulation becomes significant with the increase of the constriction angle and fluid viscosity. The SSAW can effectively reduce the particle accumulation and postpone clogging. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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17 pages, 6471 KiB

Open AccessArticle

Quantitative Assessment of First Annular Pulley and Adjacent Tissues Using High-Frequency Ultrasound

by Yi-Hsun Lin¹, Tai-Hua Yang², Shyh-Hau Wang^1,3,*

and Fong-Chin Su^2,3

¹ Department of Computer Science and Information Engineering & Institute of Medical Informatics, National Cheng Kung University, No. 1, University Road, Tainan City 70101, Taiwan

² Department of Biomedical Engineering, National Cheng Kung University, No. 1, University Road, Tainan City 70101, Taiwan

³ Medical Device Innovation Center, National Cheng Kung University, No. 1, University Road, Tainan City 70101, Taiwan

Sensors 2017, 17(1), 107; https://doi.org/10.3390/s17010107 - 7 Jan 2017

Cited by 7 | Viewed by 6729

Abstract

Due to a lack of appropriate image resolution, most ultrasound scanners are unable to sensitively discern the pulley tissues. To extensively investigate the properties of the A1 pulley system and the surrounding tissues for assessing trigger finger, a 30 MHz ultrasound system was [...] Read more.

Due to a lack of appropriate image resolution, most ultrasound scanners are unable to sensitively discern the pulley tissues. To extensively investigate the properties of the A1 pulley system and the surrounding tissues for assessing trigger finger, a 30 MHz ultrasound system was implemented to perform in vitro experiments using the hypodermis, A1 pulley, and superficial digital flexor tendon (SDFT) dissected from cadavers. Ultrasound signals were acquired from both the transverse and sagittal planes of each tissue sample. The quantitative ultrasonic parameters, including sound speed, attenuation coefficient, integrated backscatter (IB) and Nakagami parameter (m), were subsequently estimated to characterize the tissue properties. The results demonstrated that the acquired ultrasound images have high resolution and are able to sufficiently differentiate the variations of tissue textures. Moreover, the attenuation slope of the hypodermis is larger than those of the A1 pulley and SDFT. The IB of A1 pulley is about the same as that of the hypodermis, and is very different from SDFT. The m parameter of the A1 pulley is also very different from those of hypodermis and SDFT. This study demonstrated that high-frequency ultrasound images in conjunction with ultrasonic parameters are capable of characterizing the A1 pulley system and surrounding tissues. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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12 pages, 4606 KiB

Open AccessArticle

A Wirelessly Powered Smart Contact Lens with Reconfigurable Wide Range and Tunable Sensitivity Sensor Readout Circuitry

by Jin-Chern Chiou^1,2, Shun-Hsi Hsu^1,*

, Yu-Chieh Huang²

, Guan-Ting Yeh², Wei-Ting Liou² and Cheng-Kai Kuei²

¹ Department of Electrical and Computer Engineering, National Chiao-Tung University, Room 617, Engineering Building 5, No. 1001, Ta Hsueh Rd., Hsinchu 30010, Taiwan

² Institute of Electrical Control Engineering, National Chiao-Tung University, Room 617, Engineering Building 5, No. 1001, Ta Hsueh Rd., Hsinchu 30010, Taiwan

Sensors 2017, 17(1), 108; https://doi.org/10.3390/s17010108 - 7 Jan 2017

Cited by 59 | Viewed by 14245

Abstract

This study presented a wireless smart contact lens system that was composed of a reconfigurable capacitive sensor interface circuitry and wirelessly powered radio-frequency identification (RFID) addressable system for sensor control and data communication. In order to improve compliance and reduce user discomfort, a [...] Read more.

This study presented a wireless smart contact lens system that was composed of a reconfigurable capacitive sensor interface circuitry and wirelessly powered radio-frequency identification (RFID) addressable system for sensor control and data communication. In order to improve compliance and reduce user discomfort, a capacitive sensor was embedded on a soft contact lens of 200 μm thickness using commercially available bio-compatible lens material and a standard manufacturing process. The results indicated that the reconfigurable sensor interface achieved sensitivity and baseline tuning up to 120 pF while consuming only 110 μW power. The range and sensitivity tuning of the readout circuitry ensured a reliable operation with respect to sensor fabrication variations and independent calibration of the sensor baseline for individuals. The on-chip voltage scaling allowed the further extension of the detection range and prevented the implementation of large on-chip elements. The on-lens system enabled the detection of capacitive variation caused by pressure changes in the range of 2.25 to 30 mmHg and hydration level variation from a distance of 1 cm using incident power from an RFID reader at 26.5 dBm. Full article

(This article belongs to the Special Issue Smart Sensor Interface Circuits and Systems)

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20 pages, 6489 KiB

Open AccessArticle

SDTCP: Towards Datacenter TCP Congestion Control with SDN for IoT Applications

by Yifei Lu^1,3,*

, Zhen Ling^2,3, Shuhong Zhu¹ and Ling Tang¹

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

² School of Computer Science and Engineering, Southeast University, Nanjing 211189, China

³ Key Laboratory of Computer Network and Information Integration, Southeast University, Ministry of Education, Nanjing 211189, China

Sensors 2017, 17(1), 109; https://doi.org/10.3390/s17010109 - 8 Jan 2017

Cited by 54 | Viewed by 9163

Abstract

The Internet of Things (IoT) has gained popularity in recent years. Today’s IoT applications are now increasingly deployed in cloud platforms to perform Big Data analytics. In cloud data center networks (DCN), TCP incast usually happens when multiple senders simultaneously communicate with a [...] Read more.

The Internet of Things (IoT) has gained popularity in recent years. Today’s IoT applications are now increasingly deployed in cloud platforms to perform Big Data analytics. In cloud data center networks (DCN), TCP incast usually happens when multiple senders simultaneously communicate with a single receiver. However, when TCP incast happens, DCN may suffer from both throughput collapse for TCP burst flows and temporary starvation for TCP background flows. In this paper, we propose a software defined network (SDN)-based TCP congestion control mechanism, referred to as SDTCP, to leverage the features, e.g., centralized control methods and the global view of the network, in order to solve the TCP incast problems. When we detect network congestion on an OpenFlow switch, our controller can select the background flows and reduce their bandwidth by adjusting the advertised window of TCP ACK packets of the corresponding background flows so as to reserve more bandwidth for burst flows. SDTCP is transparent to the end systems and can accurately decelerate the rate of background flows by leveraging the global view of the network gained via SDN. The experiments demonstrate that our SDTCP can provide high tolerance for burst flows and achieve better flow completion time for short flows. Therefore, SDTCP is an effective and scalable solution for the TCP incast problem. Full article

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

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14 pages, 2764 KiB

Open AccessArticle

Automated Surveillance of Fruit Flies

by Ilyas Potamitis^1,*

, Iraklis Rigakis² and Nicolaos-Alexandros Tatlas³

¹ Department of Music Technology & Acoustics, Technological Educational Institute of Crete, Rethymno Crete 74100, Greece

² Department of Electronics, Technological Educational Institute of Crete, Chania Crete 73133, Greece

³ Department of Electronics Engineering, Piraeus University of Applied Sciences, Athens 12244, Greece

Sensors 2017, 17(1), 110; https://doi.org/10.3390/s17010110 - 8 Jan 2017

Cited by 48 | Viewed by 10902

Abstract

Insects of the Diptera order of the Tephritidae family cause costly, annual crop losses worldwide. Monitoring traps are important components of integrated pest management programs used against fruit flies. Here we report the modification of typical, low-cost plastic traps for fruit flies by [...] Read more.

Insects of the Diptera order of the Tephritidae family cause costly, annual crop losses worldwide. Monitoring traps are important components of integrated pest management programs used against fruit flies. Here we report the modification of typical, low-cost plastic traps for fruit flies by adding the necessary optoelectronic sensors to monitor the entrance of the trap in order to detect, time-stamp, GPS tag, and identify the species of incoming insects from the optoacoustic spectrum analysis of their wingbeat. We propose that the incorporation of automated streaming of insect counts, environmental parameters and GPS coordinates into informative visualization of collective behavior will finally enable better decision making across spatial and temporal scales, as well as administrative levels. The device presented is at product level of maturity as it has solved many pending issues presented in a previously reported study. Full article

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

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17 pages, 2540 KiB

Open AccessArticle

A Non-Invasive Multichannel Hybrid Fiber-Optic Sensor System for Vital Sign Monitoring

by Marcel Fajkus^1,*

, Jan Nedoma¹

, Radek Martinek²

, Vladimir Vasinek¹, Homer Nazeran³ and Petr Siska¹

¹ Department of Telecommunications, Faculty of Electrical Engineering and Computer Science, VSB–Technical University of Ostrava, 17 Listopadu 15, Ostrava 70833, Czech Republic

² Department of Cybernetics and Biomedical Engineering, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, 17 Listopadu 15, Ostrava 70833, Czech Republic

³ Department of Electrical and Computer Engineering, University of Texas El Paso, 500W University Ave, El Paso, TX 79968, USA

Sensors 2017, 17(1), 111; https://doi.org/10.3390/s17010111 - 8 Jan 2017

Cited by 158 | Viewed by 11704

Abstract

In this article, we briefly describe the design, construction, and functional verification of a hybrid multichannel fiber-optic sensor system for basic vital sign monitoring. This sensor uses a novel non-invasive measurement probe based on the fiber Bragg grating (FBG). The probe is composed [...] Read more.

In this article, we briefly describe the design, construction, and functional verification of a hybrid multichannel fiber-optic sensor system for basic vital sign monitoring. This sensor uses a novel non-invasive measurement probe based on the fiber Bragg grating (FBG). The probe is composed of two FBGs encapsulated inside a polydimethylsiloxane polymer (PDMS). The PDMS is non-reactive to human skin and resistant to electromagnetic waves, UV absorption, and radiation. We emphasize the construction of the probe to be specifically used for basic vital sign monitoring such as body temperature, respiratory rate and heart rate. The proposed sensor system can continuously process incoming signals from up to 128 individuals. We first present the overall design of this novel multichannel sensor and then elaborate on how it has the potential to simplify vital sign monitoring and consequently improve the comfort level of patients in long-term health care facilities, hospitals and clinics. The reference ECG signal was acquired with the use of standard gel electrodes fixed to the monitored person's chest using a real-time monitoring system for ECG signals with virtual instrumentation. The outcomes of these experiments have unambiguously proved the functionality of the sensor system and will be used to inform our future research in this fast developing and emerging field. Full article

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

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16 pages, 4955 KiB

Open AccessArticle

Trunk Motion System (TMS) Using Printed Body Worn Sensor (BWS) via Data Fusion Approach

by Mohammad Iman Mokhlespour Esfahani^1,2,*, Omid Zobeiri³, Behzad Moshiri⁴, Roya Narimani², Mohammad Mehravar⁵

, Ehsan Rashedi⁶ and Mohamad Parnianpour²

¹ Department of Industrial and Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA

² Laboratory of Wearable Technologies and Neuromusculoskeletal Research, School of Mechanical Engineering, Sharif University of Technology, Tehran 11155-9567, Iran

³ Department of Biomedical Engineering, McGill University, Montréal, QC H3A 2B4, Canada

⁴ Control and Intelligent Processing, Center of Excellence, School of Electrical and Computer Engineering, University of Tehran, Tehran 14395-515, Iran

⁵ Musculoskeletal Rehabilitation Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz 6135733133, Iran

⁶ Department of Industrial and Systems Engineering, Rochester Institute of Technology, Rochester, NY 14623-5603, USA

Sensors 2017, 17(1), 112; https://doi.org/10.3390/s17010112 - 8 Jan 2017

Cited by 38 | Viewed by 7613

Abstract

Human movement analysis is an important part of biomechanics and rehabilitation, for which many measurement systems are introduced. Among these, wearable devices have substantial biomedical applications, primarily since they can be implemented both in indoor and outdoor applications. In this study, a Trunk [...] Read more.

Human movement analysis is an important part of biomechanics and rehabilitation, for which many measurement systems are introduced. Among these, wearable devices have substantial biomedical applications, primarily since they can be implemented both in indoor and outdoor applications. In this study, a Trunk Motion System (TMS) using printed Body-Worn Sensors (BWS) is designed and developed. TMS can measure three-dimensional (3D) trunk motions, is lightweight, and is a portable and non-invasive system. After the recognition of sensor locations, twelve BWSs were printed on stretchable clothing with the purpose of measuring the 3D trunk movements. To integrate BWSs data, a neural network data fusion algorithm was used. The outcome of this algorithm along with the actual 3D anatomical movements (obtained by Qualisys system) were used to calibrate the TMS. Three healthy participants with different physical characteristics participated in the calibration tests. Seven different tasks (each repeated three times) were performed, involving five planar, and two multiplanar movements. Results showed that the accuracy of TMS system was less than 1.0°, 0.8°, 0.6°, 0.8°, 0.9°, and 1.3° for flexion/extension, left/right lateral bending, left/right axial rotation, and multi-planar motions, respectively. In addition, the accuracy of TMS for the identified movement was less than 2.7°. TMS, developed to monitor and measure the trunk orientations, can have diverse applications in clinical, biomechanical, and ergonomic studies to prevent musculoskeletal injuries, and to determine the impact of interventions. Full article

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

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16 pages, 648 KiB

Open AccessArticle

A Fast Synthetic Aperture Radar Raw Data Simulation Using Cloud Computing

by Zhixin Li, Dandan Su, Haijiang Zhu, Wei Li, Fan Zhang^*

and Ruirui Li^*

College of Information Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China

Sensors 2017, 17(1), 113; https://doi.org/10.3390/s17010113 - 8 Jan 2017

Cited by 15 | Viewed by 5855

Abstract

Synthetic Aperture Radar (SAR) raw data simulation is a fundamental problem in radar system design and imaging algorithm research. The growth of surveying swath and resolution results in a significant increase in data volume and simulation period, which can be considered to be [...] Read more.

Synthetic Aperture Radar (SAR) raw data simulation is a fundamental problem in radar system design and imaging algorithm research. The growth of surveying swath and resolution results in a significant increase in data volume and simulation period, which can be considered to be a comprehensive data intensive and computing intensive issue. Although several high performance computing (HPC) methods have demonstrated their potential for accelerating simulation, the input/output (I/O) bottleneck of huge raw data has not been eased. In this paper, we propose a cloud computing based SAR raw data simulation algorithm, which employs the MapReduce model to accelerate the raw data computing and the Hadoop distributed file system (HDFS) for fast I/O access. The MapReduce model is designed for the irregular parallel accumulation of raw data simulation, which greatly reduces the parallel efficiency of graphics processing unit (GPU) based simulation methods. In addition, three kinds of optimization strategies are put forward from the aspects of programming model, HDFS configuration and scheduling. The experimental results show that the cloud computing based algorithm achieves 4_ speedup over the baseline serial approach in an 8-node cloud environment, and each optimization strategy can improve about 20%. This work proves that the proposed cloud algorithm is capable of solving the computing intensive and data intensive issues in SAR raw data simulation, and is easily extended to large scale computing to achieve higher acceleration. Full article

(This article belongs to the Section Remote Sensors)

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17 pages, 7756 KiB

Open AccessArticle

Pull-In Effect of Suspended Microchannel Resonator Sensor Subjected to Electrostatic Actuation

by Han Yan¹, Wen-Ming Zhang^1,*, Hui-Ming Jiang¹ and Kai-Ming Hu^1,2

¹ State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

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

Sensors 2017, 17(1), 114; https://doi.org/10.3390/s17010114 - 8 Jan 2017

Cited by 11 | Viewed by 7433

Abstract

In this article, the pull-in instability and dynamic characteristics of electrostatically actuated suspended microchannel resonators are studied. A theoretical model is presented to describe the pull-in effect of suspended microchannel resonators by considering the electrostatic field and the internal fluid. The results indicate [...] Read more.

In this article, the pull-in instability and dynamic characteristics of electrostatically actuated suspended microchannel resonators are studied. A theoretical model is presented to describe the pull-in effect of suspended microchannel resonators by considering the electrostatic field and the internal fluid. The results indicate that the system is subjected to both the pull-in instability and the flutter. The former is induced by the applied voltage which exceeds the pull-in value while the latter occurs as the velocity of steady flow get closer to the critical velocity. The statically and dynamically stable regions are presented by thoroughly studying the two forms of instability. It is demonstrated that the steady flow can remarkably extend the dynamic stable range of pull-in while the applied voltage slightly decreases the critical velocity. It is also shown that the dc voltage and the steady flow can adjust the resonant frequency while the ac voltage can modulate the vibrational amplitude of the resonator. Full article

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

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15 pages, 12940 KiB

Open AccessArticle

Software Defined Doppler Radar as a Contactless Multipurpose Microwave Sensor for Vibrations Monitoring

by Antonio Raffo, Sandra Costanzo^*

and Giuseppe Di Massa

Department of Computer Engineering, Modelling, Electronics, and Systems Science (DIMES), University of Calabria, 87036 Rende, Italy

Sensors 2017, 17(1), 115; https://doi.org/10.3390/s17010115 - 8 Jan 2017

Cited by 16 | Viewed by 10492

Abstract

A vibration sensor based on the use of a Software-Defined Radio (SDR) platform is adopted in this work to provide a contactless and multipurpose solution for low-cost real-time vibrations monitoring. In order to test the vibration detection ability of the proposed non-contact method, [...] Read more.

A vibration sensor based on the use of a Software-Defined Radio (SDR) platform is adopted in this work to provide a contactless and multipurpose solution for low-cost real-time vibrations monitoring. In order to test the vibration detection ability of the proposed non-contact method, a 1 GHz Doppler radar sensor is simulated and successfully assessed on targets at various distances, with various oscillation frequencies and amplitudes. Furthermore, an SDR Doppler platform is practically realized, and preliminary experimental validations on a device able to produce a harmonic motion are illustrated to prove the effectiveness of the proposed approach. Full article

(This article belongs to the Special Issue Non-Contact Sensing)

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21 pages, 875 KiB

Open AccessArticle

A Novel Monopulse Technique for Adaptive Phased Array Radar

by Xinyu Zhang^1,3, Yang Li^1,4,*, Xiaopeng Yang¹, Le Zheng², Teng Long¹ and Christopher J. Baker³

¹ Department of Information and Electronics Engineering, Beijing Institute of Technology, Beijing 100081, China

² School of Electrical Engineering, Columbia University, New York, NY 10027, USA

³ ElectroScience Laboratory, Ohio State University, Columbus, OH 43212, USA

⁴ Beijing Key Laboratory of Embedded Real-time Information Processing Technology, Beijing Institute of Technology, Beijing 100081, China

Sensors 2017, 17(1), 116; https://doi.org/10.3390/s17010116 - 8 Jan 2017

Cited by 11 | Viewed by 7266

Abstract

The monopulse angle measuring technique is widely adopted in radar systems due to its simplicity and speed in accurately acquiring a target’s angle. However, in a spatial adaptive array, beam distortion, due to adaptive beamforming, can result in serious deterioration of monopulse performance. [...] Read more.

The monopulse angle measuring technique is widely adopted in radar systems due to its simplicity and speed in accurately acquiring a target’s angle. However, in a spatial adaptive array, beam distortion, due to adaptive beamforming, can result in serious deterioration of monopulse performance. In this paper, a novel constrained monopulse angle measuring algorithm is proposed for spatial adaptive arrays. This algorithm maintains the ability to suppress the unwanted signals without suffering from beam distortion. Compared with conventional adaptive monopulse methods, the proposed algorithm adopts a new form of constraint in forming the difference beam with the merit that it is more robust in most practical situations. At the same time, it also exhibits the simplicity of one-dimension monopulse, helping to make this algorithm even more appealing to use in adaptive planar arrays. The theoretical mean and variance of the proposed monopulse estimator is derived for theoretical analysis. Mathematical simulations are formulated to demonstrate the effectiveness and advantages of the proposed algorithm. Both theoretical analysis and simulation results show that the proposed algorithm can outperform the conventional adaptive monopulse methods in the presence of severe interference near the mainlobe. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 1833 KiB

Open AccessArticle

A Two-Phase Coverage-Enhancing Algorithm for Hybrid Wireless Sensor Networks

by Qingguo Zhang^1,2,* and Mable P. Fok²

¹ College of Computer, Huazhong Normal University, Wuhan 430079, China

² Lightwave and Microwave Photonics Laboratory, College of Engineering, University of Georgia, Athens, GA 30602, USA

Sensors 2017, 17(1), 117; https://doi.org/10.3390/s17010117 - 9 Jan 2017

Cited by 36 | Viewed by 5235

Abstract

Providing field coverage is a key task in many sensor network applications. In certain scenarios, the sensor field may have coverage holes due to random initial deployment of sensors; thus, the desired level of coverage cannot be achieved. A hybrid wireless sensor network [...] Read more.

Providing field coverage is a key task in many sensor network applications. In certain scenarios, the sensor field may have coverage holes due to random initial deployment of sensors; thus, the desired level of coverage cannot be achieved. A hybrid wireless sensor network is a cost-effective solution to this problem, which is achieved by repositioning a portion of the mobile sensors in the network to meet the network coverage requirement. This paper investigates how to redeploy mobile sensor nodes to improve network coverage in hybrid wireless sensor networks. We propose a two-phase coverage-enhancing algorithm for hybrid wireless sensor networks. In phase one, we use a differential evolution algorithm to compute the candidate’s target positions in the mobile sensor nodes that could potentially improve coverage. In the second phase, we use an optimization scheme on the candidate’s target positions calculated from phase one to reduce the accumulated potential moving distance of mobile sensors, such that the exact mobile sensor nodes that need to be moved as well as their final target positions can be determined. Experimental results show that the proposed algorithm provided significant improvement in terms of area coverage rate, average moving distance, area coverage–distance rate and the number of moved mobile sensors, when compare with other approaches. Full article

(This article belongs to the Section Sensor Networks)

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20 pages, 5786 KiB

Open AccessArticle

Design and Integration for High Performance Robotic Systems Based on Decomposition and Hybridization Approaches

by Dan Zhang^1,2,* and Bin Wei²

¹ School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China

² Department of Mechanical Engineering, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada

Sensors 2017, 17(1), 118; https://doi.org/10.3390/s17010118 - 9 Jan 2017

Cited by 2 | Viewed by 4928

Abstract

Currently, the uses of robotics are limited with respect to performance capabilities. Improving the performance of robotic mechanisms is and still will be the main research topic in the next decade. In this paper, design and integration for improving performance of robotic systems [...] Read more.

Currently, the uses of robotics are limited with respect to performance capabilities. Improving the performance of robotic mechanisms is and still will be the main research topic in the next decade. In this paper, design and integration for improving performance of robotic systems are achieved through three different approaches, i.e., structure synthesis design approach, dynamic balancing approach, and adaptive control approach. The purpose of robotic mechanism structure synthesis design is to propose certain mechanism that has better kinematic and dynamic performance as compared to the old ones. For the dynamic balancing design approach, it is normally accomplished based on employing counterweights or counter-rotations. The potential issue is that more weight and inertia will be included in the system. Here, reactionless based on the reconfiguration concept is put forward, which can address the mentioned problem. With the mechanism reconfiguration, the control system needs to be adapted thereafter. One way to address control system adaptation is by applying the “divide and conquer” methodology. It entails modularizing the functionalities: breaking up the control functions into small functional modules, and from those modules assembling the control system according to the changing needs of the mechanism. Full article

(This article belongs to the Special Issue Advanced Robotics and Mechatronics Devices)

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34 pages, 11586 KiB

Open AccessArticle

Fisheye-Based Method for GPS Localization Improvement in Unknown Semi-Obstructed Areas

by Julien Moreau^1,*

, Sébastien Ambellouis² and Yassine Ruichek¹

¹ UTBM IRTES-SET, Rue Ernest Thierry Mieg, 90010 Belfort CEDEX, France

² IFSTTAR-COSYS-LEOST, 20 rue Élysée Reclus, BP 70317 59666 Villeneuve d’Ascq CEDEX, France

Sensors 2017, 17(1), 119; https://doi.org/10.3390/s17010119 - 17 Jan 2017

Cited by 48 | Viewed by 10605

Abstract

A precise GNSS (Global Navigation Satellite System) localization is vital for autonomous road vehicles, especially in cluttered or urban environments where satellites are occluded, preventing accurate positioning. We propose to fuse GPS (Global Positioning System) data with fisheye stereovision to face this problem [...] Read more.

A precise GNSS (Global Navigation Satellite System) localization is vital for autonomous road vehicles, especially in cluttered or urban environments where satellites are occluded, preventing accurate positioning. We propose to fuse GPS (Global Positioning System) data with fisheye stereovision to face this problem independently to additional data, possibly outdated, unavailable, and needing correlation with reality. Our stereoscope is sky-facing with 360° × 180° fisheye cameras to observe surrounding obstacles. We propose a 3D modelling and plane extraction through following steps: stereoscope self-calibration for decalibration robustness, stereo matching considering neighbours epipolar curves to compute 3D, and robust plane fitting based on generated cartography and Hough transform. We use these 3D data with GPS raw data to estimate NLOS (Non Line Of Sight) reflected signals pseudorange delay. We exploit extracted planes to build a visibility mask for NLOS detection. A simplified 3D canyon model allows to compute reflections pseudorange delays. In the end, GPS positioning is computed considering corrected pseudoranges. With experimentations on real fixed scenes, we show generated 3D models reaching metric accuracy and improvement of horizontal GPS positioning accuracy by more than 50%. The proposed procedure is effective, and the proposed NLOS detection outperforms CN0-based methods (Carrier-to-receiver Noise density). Full article

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

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22 pages, 10841 KiB

Open AccessArticle

A Social Potential Fields Approach for Self-Deployment and Self-Healing in Hierarchical Mobile Wireless Sensor Networks

by Eva González-Parada^†

, Jose Cano-García^*,†

, Francisco Aguilera^†, Francisco Sandoval^† and Cristina Urdiales^†

¹ Departamento de Tecnologia Electronica, ETSI Telecomunicacion, Campus de Teatinos s/n, University of Malaga, Malaga 29010, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 120; https://doi.org/10.3390/s17010120 - 9 Jan 2017

Cited by 7 | Viewed by 5206

Abstract

Autonomous mobile nodes in mobile wireless sensor networks (MWSN) allow self-deployment and self-healing. In both cases, the goals are: (i) to achieve adequate coverage; and (ii) to extend network life. In dynamic environments, nodes may use reactive algorithms so that each node locally [...] Read more.

Autonomous mobile nodes in mobile wireless sensor networks (MWSN) allow self-deployment and self-healing. In both cases, the goals are: (i) to achieve adequate coverage; and (ii) to extend network life. In dynamic environments, nodes may use reactive algorithms so that each node locally decides when and where to move. This paper presents a behavior-based deployment and self-healing algorithm based on the social potential fields algorithm. In the proposed algorithm, nodes are attached to low cost robots to autonomously navigate in the coverage area. The proposed algorithm has been tested in environments with and without obstacles. Our study also analyzes the differences between non-hierarchical and hierarchical routing configurations in terms of network life and coverage. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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17 pages, 8321 KiB

Open AccessArticle

Visual Object Tracking Based on Cross-Modality Gaussian-Bernoulli Deep Boltzmann Machines with RGB-D Sensors

by Mingxin Jiang¹, Zhigeng Pan² and Zhenzhou Tang^3,*

¹ Faculty of Computer and Software Engineering, Huaiyin Institute of Technology, Huai’an 223003, China

² Digital Media &Interaction Research Center, Hangzhou Normal University, Hangzhou 310012, China

³ College of Physics and Electronic Information Engineering, Wenzhou University, Wenzhou 325035, China

Sensors 2017, 17(1), 121; https://doi.org/10.3390/s17010121 - 10 Jan 2017

Cited by 13 | Viewed by 6336

Abstract

Visual object tracking technology is one of the key issues in computer vision. In this paper, we propose a visual object tracking algorithm based on cross-modality featuredeep learning using Gaussian-Bernoulli deep Boltzmann machines (DBM) with RGB-D sensors. First, a cross-modality featurelearning network based [...] Read more.

Visual object tracking technology is one of the key issues in computer vision. In this paper, we propose a visual object tracking algorithm based on cross-modality featuredeep learning using Gaussian-Bernoulli deep Boltzmann machines (DBM) with RGB-D sensors. First, a cross-modality featurelearning network based on aGaussian-Bernoulli DBM is constructed, which can extract cross-modality features of the samples in RGB-D video data. Second, the cross-modality features of the samples are input into the logistic regression classifier, andthe observation likelihood model is established according to the confidence score of the classifier. Finally, the object tracking results over RGB-D data are obtained using aBayesian maximum a posteriori (MAP) probability estimation algorithm. The experimental results show that the proposed method has strong robustness to abnormal changes (e.g., occlusion, rotation, illumination change, etc.). The algorithm can steadily track multiple targets and has higher accuracy. Full article

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

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18 pages, 4828 KiB

Open AccessArticle

Distributed Sensor Nodes Charged by Mobile Charger with Directional Antenna and by Energy Trading for Balancing

by Celso Moraes, Sunghee Myung, Sangkeum Lee and Dongsoo Har^*

Cho Chun Shik Graduate School of Green Transportation, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea

Sensors 2017, 17(1), 122; https://doi.org/10.3390/s17010122 - 10 Jan 2017

Cited by 29 | Viewed by 5253

Abstract

Provision of energy to wireless sensor networks is crucial for their sustainable operation. Sensor nodes are typically equipped with batteries as their operating energy sources. However, when the sensor nodes are sited in almost inaccessible locations, replacing their batteries incurs high maintenance cost. [...] Read more.

Provision of energy to wireless sensor networks is crucial for their sustainable operation. Sensor nodes are typically equipped with batteries as their operating energy sources. However, when the sensor nodes are sited in almost inaccessible locations, replacing their batteries incurs high maintenance cost. Under such conditions, wireless charging of sensor nodes by a mobile charger with an antenna can be an efficient solution. When charging distributed sensor nodes, a directional antenna, rather than an omnidirectional antenna, is more energy-efficient because of smaller proportion of off-target radiation. In addition, for densely distributed sensor nodes, it can be more effective for some undercharged sensor nodes to harvest energy from neighboring overcharged sensor nodes than from the remote mobile charger, because this reduces the pathloss of charging signal due to smaller distances. In this paper, we propose a hybrid charging scheme that combines charging by a mobile charger with a directional antenna, and energy trading, e.g., transferring and harvesting, between neighboring sensor nodes. The proposed scheme is compared with other charging scheme. Simulations demonstrate that the hybrid charging scheme with a directional antenna achieves a significant reduction in the total charging time required for all sensor nodes to reach a target energy level. Full article

(This article belongs to the Section Sensor Networks)

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18 pages, 4266 KiB

Open AccessArticle

High-Performance Anti-Retransmission Deception Jamming Utilizing Range Direction Multiple Input and Multiple Output (MIMO) Synthetic Aperture Radar (SAR)

by Ruijia Wang^1,*, Jie Chen^2,3,*, Xing Wang¹ and Bing Sun^2,3

¹ Aeronautics and Astronautics Engineering College, Air Force Engineering University, Xi’an 710038, China

² School of Electronics and Information Engineering, Beihang University, Beijing 100084, China

³ Collaborative Innovation Center of Geospatial Technology, Wuhan 430079, China

Sensors 2017, 17(1), 123; https://doi.org/10.3390/s17010123 - 9 Jan 2017

Cited by 14 | Viewed by 5107

Abstract

Retransmission deception jamming seriously degrades the Synthetic Aperture Radar (SAR) detection efficiency and can mislead SAR image interpretation by forming false targets. In order to suppress retransmission deception jamming, this paper proposes a novel multiple input and multiple output (MIMO) SAR structure range [...] Read more.

Retransmission deception jamming seriously degrades the Synthetic Aperture Radar (SAR) detection efficiency and can mislead SAR image interpretation by forming false targets. In order to suppress retransmission deception jamming, this paper proposes a novel multiple input and multiple output (MIMO) SAR structure range direction MIMO SAR, whose multiple channel antennas are vertical to the azimuth. First, based on the multiple channels of range direction MIMO SAR, the orthogonal frequency division multiplexing (OFDM) linear frequency modulation (LFM) signal was adopted as the transmission signal of each channel, which is defined as a sub-band signal. This sub-band signal corresponds to the transmission channel. Then, all of the sub-band signals are modulated with random initial phases and concurrently transmitted. The signal form is more complex and difficult to intercept. Next, the echoes of the sub-band signal are utilized to synthesize a wide band signal after preprocessing. The proposed method will increase the signal to interference ratio and peak amplitude ratio of the signal to resist retransmission deception jamming. Finally, well-focused SAR imagery is obtained using a conventional imaging method where the retransmission deception jamming strength is degraded and defocused. Simulations demonstrated the effectiveness of the proposed method. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 1304 KiB

Open AccessArticle

Dynamic Oil-in-Water Concentration Acquisition on a Pilot-Scaled Offshore Water-Oil Separation Facility

by Petar Durdevic^1,*,†,‡, Chitra S. Raju^2,‡, Mads V. Bram^1,‡, Dennis S. Hansen^1,‡ and Zhenyu Yang^1,‡

¹ Department of Energy Technology, Aalborg University, Esbjerg 6700, Denmark

² Independent Consultant, Esbjerg 6700, Denmark

^† Current address: Niels Bohrs Vej 8, Esbjerg 6700, Denmark.

^‡ These authors contributed equally to this work.

Sensors 2017, 17(1), 124; https://doi.org/10.3390/s17010124 - 10 Jan 2017

Cited by 12 | Viewed by 5543

Abstract

This article is a feasibility study on using fluorescence-based oil-in-water (OiW) monitors for on-line dynamic efficiency measurement of a deoiling hydrocyclone. Dynamic measurements are crucial in the design and validation of dynamic models of the hydrocyclones, and to our knowledge, no dynamic OiW [...] Read more.

This article is a feasibility study on using fluorescence-based oil-in-water (OiW) monitors for on-line dynamic efficiency measurement of a deoiling hydrocyclone. Dynamic measurements are crucial in the design and validation of dynamic models of the hydrocyclones, and to our knowledge, no dynamic OiW analysis of hydrocyclones has been carried out. Previous studies have extensively studied the steady state efficiency perspective of hydrocyclones, and have related them to different key parameters, such as the pressure drop ratio (PDR), inlet flow rate, and the flow-spilt. Through our study, we were able to measure the dynamics of the hydrocyclone’s efficiency

(ϵ)

response to step changes in the inlet flow rate with high accuracy. This is a breakthrough in the modelling, control, and monitoring of hydrocyclones. Full article

(This article belongs to the Section Chemical Sensors)

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18 pages, 3566 KiB

Open AccessArticle

An Approach to Biometric Verification Based on Human Body Communication in Wearable Devices

by Jingzhen Li, Yuhang Liu, Zedong Nie^*

, Wenjian Qin, Zengyao Pang and Lei Wang

Shenzhen Institutes of Advanced Technology, Chinese Academy of Science, Shenzhen 518055, China

Sensors 2017, 17(1), 125; https://doi.org/10.3390/s17010125 - 10 Jan 2017

Cited by 16 | Viewed by 6365

Abstract

In this paper, an approach to biometric verification based on human body communication (HBC) is presented for wearable devices. For this purpose, the transmission gain S21 of volunteer’s forearm is measured by vector network analyzer (VNA). Specifically, in order to determine the chosen [...] Read more.

In this paper, an approach to biometric verification based on human body communication (HBC) is presented for wearable devices. For this purpose, the transmission gain S21 of volunteer’s forearm is measured by vector network analyzer (VNA). Specifically, in order to determine the chosen frequency for biometric verification, 1800 groups of data are acquired from 10 volunteers in the frequency range 0.3 MHz to 1500 MHz, and each group includes 1601 sample data. In addition, to achieve the rapid verification, 30 groups of data for each volunteer are acquired at the chosen frequency, and each group contains only 21 sample data. Furthermore, a threshold-adaptive template matching (TATM) algorithm based on weighted Euclidean distance is proposed for rapid verification in this work. The results indicate that the chosen frequency for biometric verification is from 650 MHz to 750 MHz. The false acceptance rate (FAR) and false rejection rate (FRR) based on TATM are approximately 5.79% and 6.74%, respectively. In contrast, the FAR and FRR were 4.17% and 37.5%, 3.37% and 33.33%, and 3.80% and 34.17% using K-nearest neighbor (KNN) classification, support vector machines (SVM), and naive Bayesian method (NBM) classification, respectively. In addition, the running time of TATM is 0.019 s, whereas the running times of KNN, SVM and NBM are 0.310 s, 0.0385 s, and 0.168 s, respectively. Therefore, TATM is suggested to be appropriate for rapid verification use in wearable devices. Full article

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

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15 pages, 6805 KiB

Open AccessArticle

A Distance Detector with a Strip Magnetic MOSFET and Readout Circuit

by Guo-Ming Sung^*, Wen-Sheng Lin and Hsing-Kuang Wang

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

Sensors 2017, 17(1), 126; https://doi.org/10.3390/s17010126 - 10 Jan 2017

Cited by 2 | Viewed by 5948

Abstract

This paper presents a distance detector composed of two separated metal-oxide semiconductor field-effect transistors (MOSFETs), a differential polysilicon cross-shaped Hall plate (CSHP), and a readout circuit. The distance detector was fabricated using 0.18 μm 1P6M Complementary Metal-Oxide Semiconductor (CMOS) technology to sense the [...] Read more.

This paper presents a distance detector composed of two separated metal-oxide semiconductor field-effect transistors (MOSFETs), a differential polysilicon cross-shaped Hall plate (CSHP), and a readout circuit. The distance detector was fabricated using 0.18 μm 1P6M Complementary Metal-Oxide Semiconductor (CMOS) technology to sense the magnetic induction perpendicular to the chip surface. The differential polysilicon CSHP enabled the magnetic device to not only increase the magnetosensitivity but also eliminate the offset voltage generated because of device mismatch and Lorentz force. Two MOSFETs generated two drain currents with a quadratic function of the differential Hall voltages at CSHP. A readout circuit—composed of a current-to-voltage converter, a low-pass filter, and a difference amplifier—was designed to amplify the current difference between two drains of MOSFETs. Measurements revealed that the electrostatic discharge (ESD) could be eliminated from the distance sensor by grounding it to earth; however, the sensor could be desensitized by ESD in the absence of grounding. The magnetic influence can be ignored if the magnetic body (human) stays far from the magnetic sensor, and the measuring system is grounded to earth by using the ESD wrist strap (Strap E-GND). Both ‘no grounding’ and ‘grounding to power supply’ conditions were unsuitable for measuring the induced Hall voltage. Full article

(This article belongs to the Special Issue Magnetoelectric Heterostructures and Sensors)

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22 pages, 1483 KiB

Open AccessArticle

Enriching Mental Health Mobile Assessment and Intervention with Situation Awareness

by Ariel Soares Teles^1,*

, Artur Rocha², Francisco José da Silva e Silva¹

, João Correia Lopes^2,3, Donal O’Sullivan⁴, Pepijn Van de Ven⁴ and Markus Endler⁵

¹ Graduate Program in Electrical Engineering, Federal University of Maranhão, 65080-805 São Luís, Brazil

² Centre for Information Systems and Computer Graphics, Institute for Systems Engineering and Computers, Technology and Science, 4200-465 Porto, Portugal

³ Department of Informatics Engineering, Faculdade de Engenharia da Universidade do Porto, 4200-465 Porto, Portugal

⁴ Department of Electronic and Computer Engineering, University of Limerick, V94 T9PX Limerick, Ireland

⁵ Department of Informatics, Pontifícia Universidade Católica do Rio de Janeiro, 22453-900 Rio de Janeiro, Brazil

Sensors 2017, 17(1), 127; https://doi.org/10.3390/s17010127 - 10 Jan 2017

Cited by 18 | Viewed by 7394

Abstract

Current mobile devices allow the execution of sophisticated applications with the capacity for identifying the user situation, which can be helpful in treatments of mental disorders. In this paper, we present SituMan, a solution that provides situation awareness to MoodBuster, an [...] Read more.

Current mobile devices allow the execution of sophisticated applications with the capacity for identifying the user situation, which can be helpful in treatments of mental disorders. In this paper, we present SituMan, a solution that provides situation awareness to MoodBuster, an ecological momentary assessment and intervention mobile application used to request self-assessments from patients in depression treatments. SituMan has a fuzzy inference engine to identify patient situations using context data gathered from the sensors embedded in mobile devices. Situations are specified jointly by the patient and mental health professional, and they can represent the patient’s daily routine (e.g., “studying”, “at work”, “working out”). MoodBuster requests mental status self-assessments from patients at adequate moments using situation awareness. In addition, SituMan saves and displays patient situations in a summary, delivering them for consultation by mental health professionals. A first experimental evaluation was performed to assess the user satisfaction with the approaches to define and identify situations. This experiment showed that SituMan was well evaluated in both criteria. A second experiment was performed to assess the accuracy of the fuzzy engine to infer situations. Results from the second experiment showed that the fuzzy inference engine has a good accuracy to identify situations. Full article

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

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19 pages, 3187 KiB

Open AccessArticle

Epipolar Resampling of Cross-Track Pushbroom Satellite Imagery Using the Rigorous Sensor Model

by Mojtaba Jannati^*

, Mohammad Javad Valadan Zoej

and Mehdi Mokhtarzade

Faculty of Geodesy and Geomatics, K. N. Toosi University of Technology, Tehran 19667-15433, Iran

Sensors 2017, 17(1), 129; https://doi.org/10.3390/s17010129 - 11 Jan 2017

Cited by 11 | Viewed by 5370

Abstract

Epipolar resampling aims to eliminate the vertical parallax of stereo images. Due to the dynamic nature of the exterior orientation parameters of linear pushbroom satellite imagery and the complexity of reconstructing the epipolar geometry using rigorous sensor models, so far, no epipolar resampling [...] Read more.

Epipolar resampling aims to eliminate the vertical parallax of stereo images. Due to the dynamic nature of the exterior orientation parameters of linear pushbroom satellite imagery and the complexity of reconstructing the epipolar geometry using rigorous sensor models, so far, no epipolar resampling approach has been proposed based on these models. In this paper for the first time it is shown that the orientation of the instantaneous baseline (IB) of conjugate image points (CIPs) in the linear pushbroom satellite imagery can be modeled with high precision in terms of the rows- and the columns-number of CIPs. Taking advantage of this feature, a novel approach is then presented for epipolar resampling of cross-track linear pushbroom satellite imagery. The proposed method is based on the rigorous sensor model. As the instantaneous position of sensors remains fixed, the digital elevation model of the area of interest is not required in the resampling process. Experimental results obtained from two pairs of SPOT and one pair of RapidEye stereo imagery with different terrain conditions shows that the proposed epipolar resampling approach benefits from a superior accuracy, as the remained vertical parallaxes of all CIPs in the normalized images are close to zero. Full article

(This article belongs to the Section Remote Sensors)

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12 pages, 4102 KiB

Open AccessArticle

Stylus Tip Center Position Self-Calibration Based on Invariable Distances in Light-Pen Systems

by Rui Zhang^*, Shugui Liu, Sen Wang and Xuanxiao Song

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

Sensors 2017, 17(1), 131; https://doi.org/10.3390/s17010131 - 11 Jan 2017

Cited by 10 | Viewed by 4742

Abstract

The light-pen coordinate measuring machine (LPCMM for short) is portable and flexible to measure features including invisible ones in-situ. Since different styluses are needed to measure different features and even during the process of measuring a single workpiece with complicated configurations, to improve [...] Read more.

The light-pen coordinate measuring machine (LPCMM for short) is portable and flexible to measure features including invisible ones in-situ. Since different styluses are needed to measure different features and even during the process of measuring a single workpiece with complicated configurations, to improve the system measurement accuracy it is beneficial to calibrate the stylus tip center position after it is mounted to the light-pen before measurement in an industrial field. A novel and simple method aiming at self-calibrating the position of the tip center based on invariable distances is presented. The distinguishing feature of the proposed method is that the center position of the tip can be calibrated by using a kinematic seat with an inverted cone hole without any external reference and auxiliary devices. Calibration is based on that the distance between the tip center and that of any LED is invariable when the light-pen is swung smoothly with its spherical tip firmly touching the fixed cone seat. To ensure the repeatability of the algorithm some error constraint parameters are given. Based on invariable distances, the tip center position in the light-pen coordinate system can be obtained. Experiment results show that the self-calibration method has the advantage of good repeatability, with standard deviations 0.027, 0.023 and 0.014 mm in U, V and W directions, respectively. Experimental results of measuring a circle and a gauge block indirectly demonstrate the accuracy of the proposed self-calibration method. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 2992 KiB

Open AccessArticle

Multibeam Interferometer Using a Photonic Crystal Fiber with Two Asymmetric Cores for Torsion, Strain and Temperature Sensing

by Khurram Naeem¹

, Il-Bum Kwon^1,* and Youngjoo Chung^2,*

¹ Center for Safety Measurement, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Yuseong-gu, Daejeon 34113, Korea

² School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 61005, Korea

Sensors 2017, 17(1), 132; https://doi.org/10.3390/s17010132 - 11 Jan 2017

Cited by 26 | Viewed by 5123

Abstract

We present a fiber-optic multibeam Mach-Zehnder interferometer (m-MZI) for simultaneous multi-parameter measurement. The m-MZI is comprised of a section of photonic crystal fiber integrated with two independent cores of distinct construction and birefringence properties characterized for torsion, strain and temperature sensing. Due to [...] Read more.

We present a fiber-optic multibeam Mach-Zehnder interferometer (m-MZI) for simultaneous multi-parameter measurement. The m-MZI is comprised of a section of photonic crystal fiber integrated with two independent cores of distinct construction and birefringence properties characterized for torsion, strain and temperature sensing. Due to the presence of small core geometry and use of a short fiber length, the sensing device demonstrates inter-modal interference in the small core alongside the dominant inter-core interference between the cores for each of the orthogonal polarizations. The output spectrum of the device is characterized by the three-beam interference model and is polarization-dependent. The two types of interferometers present in the fiber m-MZI exhibit distinct sensitivities to torsion, strain and temperature for different polarizations, and matrix coefficients allowing simultaneous measurement of the three sensing parameters are proposed in experiment. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 2168 KiB

Open AccessArticle

Evaluation of the Performance of the Distributed Phased-MIMO Sonar

by Xiang Pan^*

, Jingning Jiang and Nan Wang

College of Information and Electronic Engineering, Zhejiang University, Hangzhou 310027, China

Sensors 2017, 17(1), 133; https://doi.org/10.3390/s17010133 - 11 Jan 2017

Cited by 6 | Viewed by 4387

Abstract

A broadband signal model is proposed for a distributed multiple-input multiple-output (MIMO) sonar system consisting of two transmitters and a receiving linear array. Transmitters are widely separated to illuminate the different aspects of an extended target of interest. The beamforming technique is utilized [...] Read more.

A broadband signal model is proposed for a distributed multiple-input multiple-output (MIMO) sonar system consisting of two transmitters and a receiving linear array. Transmitters are widely separated to illuminate the different aspects of an extended target of interest. The beamforming technique is utilized at the reception ends for enhancement of weak target echoes. A MIMO detector is designed with the estimated target position parameters within the general likelihood rate test (GLRT) framework. For the high signal-to-noise ratio case, the detection performance of the MIMO system is better than that of the phased-array system in the numerical simulations and the tank experiments. The robustness of the distributed phased-MIMO sonar system is further demonstrated in localization of a target in at-lake experiments. Full article

(This article belongs to the Section Remote Sensors)

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22 pages, 886 KiB

Open AccessArticle

On Connectivity of Wireless Sensor Networks with Directional Antennas

by Qiu Wang¹, Hong-Ning Dai^1,*

, Zibin Zheng², Muhammad Imran³

and Athanasios V. Vasilakos⁴

¹ Faculty of Information Technology, Macau University of Science and Technology, Macau, China

² School of Data and Computer Science, Sun Yat-Sen University, Guangzhou 510006, China

³ College of Computer and Information Sciences, King Saud University, Riyadh 12372, Saudi Arabia

⁴ Department of Computer Science, Electrical and Space Engineering, Lulea University of Technology, Luleå 971 87, Sweden

Sensors 2017, 17(1), 134; https://doi.org/10.3390/s17010134 - 12 Jan 2017

Cited by 42 | Viewed by 8869

Abstract

In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their [...] Read more.

In this paper, we investigate the network connectivity of wireless sensor networks with directional antennas. In particular, we establish a general framework to analyze the network connectivity while considering various antenna models and the channel randomness. Since existing directional antenna models have their pros and cons in the accuracy of reflecting realistic antennas and the computational complexity, we propose a new analytical directional antenna model called the iris model to balance the accuracy against the complexity. We conduct extensive simulations to evaluate the analytical framework. Our results show that our proposed analytical model on the network connectivity is accurate, and our iris antenna model can provide a better approximation to realistic directional antennas than other existing antenna models. Full article

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

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17 pages, 569 KiB

Open AccessArticle

Efficient DV-HOP Localization for Wireless Cyber-Physical Social Sensing System: A Correntropy-Based Neural Network Learning Scheme

by Yang Xu^1,2, Xiong Luo^1,2,*

, Weiping Wang^1,2,* and Wenbing Zhao³

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

² Beijing Key Laboratory of Knowledge Engineering for Materials Science, Beijing 100083, China

³ Department of Electrical Engineering and Computer Science, Cleveland State University, Cleveland, OH 44115, USA

Sensors 2017, 17(1), 135; https://doi.org/10.3390/s17010135 - 12 Jan 2017

Cited by 52 | Viewed by 7114

Abstract

Integrating wireless sensor network (WSN) into the emerging computing paradigm, e.g., cyber-physical social sensing (CPSS), has witnessed a growing interest, and WSN can serve as a social network while receiving more attention from the social computing research field. Then, the localization of sensor [...] Read more.

Integrating wireless sensor network (WSN) into the emerging computing paradigm, e.g., cyber-physical social sensing (CPSS), has witnessed a growing interest, and WSN can serve as a social network while receiving more attention from the social computing research field. Then, the localization of sensor nodes has become an essential requirement for many applications over WSN. Meanwhile, the localization information of unknown nodes has strongly affected the performance of WSN. The received signal strength indication (RSSI) as a typical range-based algorithm for positioning sensor nodes in WSN could achieve accurate location with hardware saving, but is sensitive to environmental noises. Moreover, the original distance vector hop (DV-HOP) as an important range-free localization algorithm is simple, inexpensive and not related to the environment factors, but performs poorly when lacking anchor nodes. Motivated by these, various improved DV-HOP schemes with RSSI have been introduced, and we present a new neural network (NN)-based node localization scheme, named RHOP-ELM-RCC, through the use of DV-HOP, RSSI and a regularized correntropy criterion (RCC)-based extreme learning machine (ELM) algorithm (ELM-RCC). Firstly, the proposed scheme employs both RSSI and DV-HOP to evaluate the distances between nodes to enhance the accuracy of distance estimation at a reasonable cost. Then, with the help of ELM featured with a fast learning speed with a good generalization performance and minimal human intervention, a single hidden layer feedforward network (SLFN) on the basis of ELM-RCC is used to implement the optimization task for obtaining the location of unknown nodes. Since the RSSI may be influenced by the environmental noises and may bring estimation error, the RCC instead of the mean square error (MSE) estimation, which is sensitive to noises, is exploited in ELM. Hence, it may make the estimation more robust against outliers. Additionally, the least square estimation (LSE) in ELM is replaced by the half-quadratic optimization technique. Simulation results show that our proposed scheme outperforms other traditional localization schemes. Full article

(This article belongs to the Special Issue New Paradigms in Cyber-Physical Social Sensing)

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12 pages, 2556 KiB

Open AccessArticle

A Mechanism for Reliable Mobility Management for Internet of Things Using CoAP

by Seung-Man Chun¹ and Jong-Tae Park^2,*

¹ Gyeongbuk Institute of IT Convergence Industry Technology, Gyeongbuk 38463, Korea

² School of Electronics Engineering, Kyungpook National University, Daegu 41566, Korea

Sensors 2017, 17(1), 136; https://doi.org/10.3390/s17010136 - 12 Jan 2017

Cited by 7 | Viewed by 5423

Abstract

Under unreliable constrained wireless networks for Internet of Things (IoT) environments, the loss of the signaling message may frequently occur. Mobile Internet Protocol version 6 (MIPv6) and its variants do not consider this situation. Consequently, as a constrained device moves around different wireless [...] Read more.

Under unreliable constrained wireless networks for Internet of Things (IoT) environments, the loss of the signaling message may frequently occur. Mobile Internet Protocol version 6 (MIPv6) and its variants do not consider this situation. Consequently, as a constrained device moves around different wireless networks, its Internet Protocol (IP) connectivity may be frequently disrupted and power can be drained rapidly. This can result in the loss of important sensing data or a large delay for time-critical IoT services such as healthcare monitoring and disaster management. This paper presents a reliable mobility management mechanism in Internet of Things environments with lossy low-power constrained device and network characteristics. The idea is to use the Internet Engineering Task Force (IETF) Constrained Application Protocol (CoAP) retransmission mechanism to achieve both reliability and simplicity for reliable IoT mobility management. Detailed architecture, algorithms, and message extensions for reliable mobility management are presented. Finally, performance is evaluated using both mathematical analysis and simulation. Full article

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

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17 pages, 2519 KiB

Open AccessArticle

Analysis of Ionospheric Scintillation Characteristics in Sub-Antarctica Region with GNSS Data at Macquarie Island

by Kai Guo¹

, Yang Liu^1,2,*, Yan Zhao¹ and Jinling Wang³

¹ School of Instrumentation Science and Opto-electronics Engineering, Beihang University, Beijing 100191, China

² Collaborative Innovation Center of Geospatial Technology, Wuhan 430079, China

³ School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia

Sensors 2017, 17(1), 137; https://doi.org/10.3390/s17010137 - 12 Jan 2017

Cited by 12 | Viewed by 6446

Abstract

Ionospheric scintillation has a great impact on radio propagation and electronic system performance, thus is extensively studied currently. The influence of scintillation on Global Navigation Satellite System (GNSS) is particularly evident, making GNSS an effective medium to study characteristics of scintillation. Ionospheric scintillation [...] Read more.

Ionospheric scintillation has a great impact on radio propagation and electronic system performance, thus is extensively studied currently. The influence of scintillation on Global Navigation Satellite System (GNSS) is particularly evident, making GNSS an effective medium to study characteristics of scintillation. Ionospheric scintillation varies greatly in relation with temporal and spatial distribution. In this paper, both temporal and spatial characteristics of scintillation are investigated based on Macquarie Island’s GNSS scintillation data collected from 2011 to 2015. Experiments demonstrate that occurrence rates of amplitude scintillation have a close relationship with solar activity, while phase scintillation is more likely to be generated by geomagnetic activity. In addition, scintillation distribution behaviors related to elevation and azimuth angles are statistically analyzed for both amplitude and phase scintillation. The proposed work is valuable for a deeper understanding of theoretical mechanisms of ionospheric scintillation in this region, and provides a reference for GNSS applications in certain regions around sub-Antarctica. Full article

(This article belongs to the Section Remote Sensors)

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29 pages, 6220 KiB

Open AccessArticle

Adaptive Information Dissemination Control to Provide Diffdelay for the Internet of Things

by Xiao Liu¹, Anfeng Liu^1,*

and Changqin Huang^2,3

¹ School of Information Science and Engineering, Central South University, Changsha 410083, China

² School of Information Technology in Education, South China Normal University, Guangzhou 510631, China

³ Beijing Hetian Yuxiang Internet Technology Co., Ltd., Beijing 100036, China

Sensors 2017, 17(1), 138; https://doi.org/10.3390/s17010138 - 12 Jan 2017

Cited by 21 | Viewed by 5661

Abstract

Applications running on the Internet of Things, such as the Wireless Sensor and Actuator Networks (WSANs) platform, generally have different quality of service (QoS) requirements. For urgent events, it is crucial that information be reported to the actuator quickly, and the communication cost [...] Read more.

Applications running on the Internet of Things, such as the Wireless Sensor and Actuator Networks (WSANs) platform, generally have different quality of service (QoS) requirements. For urgent events, it is crucial that information be reported to the actuator quickly, and the communication cost is the second factor. However, for interesting events, communication costs, network lifetime and time all become important factors. In most situations, these different requirements cannot be satisfied simultaneously. In this paper, an adaptive communication control based on a differentiated delay (ACCDS) scheme is proposed to resolve this conflict. In an ACCDS, source nodes of events adaptively send various searching actuators routings (SARs) based on the degree of sensitivity to delay while maintaining the network lifetime. For a delay-sensitive event, the source node sends a large number of SARs to actuators to identify and inform the actuators in an extremely short time; thus, action can be taken quickly but at higher communication costs. For delay-insensitive events, the source node sends fewer SARs to reduce communication costs and improve network lifetime. Therefore, an ACCDS can meet the QoS requirements of different events using a differentiated delay framework. Theoretical analysis simulation results indicate that an ACCDS provides delay and communication costs and differentiated services; an ACCDS scheme can reduce the network delay by 11.111%–53.684% for a delay-sensitive event and reduce the communication costs by 5%–22.308% for interesting events, and reduce the network lifetime by about 28.713%. Full article

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

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17 pages, 4248 KiB

Open AccessArticle

Propagation Modeling and Defending of a Mobile Sensor Worm in Wireless Sensor and Actuator Networks

by Tian Wang^1,*,†, Qun Wu^1,†, Sheng Wen², Yiqiao Cai¹, Hui Tian¹, Yonghong Chen¹ and Baowei Wang³

¹ School of Computer Science and Technology, Huaqiao University, Xiamen 361021, China

² College of Information Technology, Deakin University, Melbourne, VIC 3125, Australia

³ School of Computer and Software, Nanjing University of Information Science & Technology, Nanjing 210044, China

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 139; https://doi.org/10.3390/s17010139 - 13 Jan 2017

Cited by 59 | Viewed by 5633

Abstract

WSANs (Wireless Sensor and Actuator Networks) are derived from traditional wireless sensor networks by introducing mobile actuator elements. Previous studies indicated that mobile actuators can improve network performance in terms of data collection, energy supplementation, etc. However, according to our experimental simulations, the [...] Read more.

WSANs (Wireless Sensor and Actuator Networks) are derived from traditional wireless sensor networks by introducing mobile actuator elements. Previous studies indicated that mobile actuators can improve network performance in terms of data collection, energy supplementation, etc. However, according to our experimental simulations, the actuator’s mobility also causes the sensor worm to spread faster if an attacker launches worm attacks on an actuator and compromises it successfully. Traditional worm propagation models and defense strategies did not consider the diffusion with a mobile worm carrier. To address this new problem, we first propose a microscopic mathematical model to describe the propagation dynamics of the sensor worm. Then, a two-step local defending strategy (LDS) with a mobile patcher (a mobile element which can distribute patches) is designed to recover the network. In LDS, all recovering operations are only taken in a restricted region to minimize the cost. Extensive experimental results demonstrate that our model estimations are rather accurate and consistent with the actual spreading scenario of the mobile sensor worm. Moreover, on average, the LDS outperforms other algorithms by approximately 50% in terms of the cost. Full article

(This article belongs to the Section Sensor Networks)

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10 pages, 2984 KiB

Open AccessArticle

A Low Power Low Phase Noise Oscillator for MICS Transceivers

by Dawei Li, Dongsheng Liu^*, Chaojian Kang and Xuecheng Zou

School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430000, China

Sensors 2017, 17(1), 140; https://doi.org/10.3390/s17010140 - 12 Jan 2017

Cited by 11 | Viewed by 7734

Abstract

A low-power, low-phase-noise quadrature oscillator for Medical Implantable Communications Service (MICS) transceivers is presented. The proposed quadrature oscillator generates 349~689 MHz I/Q (In-phase and Quadrature) signals covering the MICS band. The oscillator is based on a differential pair with positive feedback. Each delay [...] Read more.

A low-power, low-phase-noise quadrature oscillator for Medical Implantable Communications Service (MICS) transceivers is presented. The proposed quadrature oscillator generates 349~689 MHz I/Q (In-phase and Quadrature) signals covering the MICS band. The oscillator is based on a differential pair with positive feedback. Each delay cell consists of a few transistors enabling lower voltage operation. Since the oscillator is very sensitive to disturbances in the supply voltage and ground, a self-bias circuit for isolating the voltage disturbance is proposed to achieve bias voltages which can track the disturbances from the supply and ground. The oscillation frequency, which is controlled by the bias voltages, is less sensitive to the supply and ground noise, and a low phase noise is achieved. The chip is fabricated in the UMC (United Microelectronics Corporation) 0.18 μm CMOS (Complementary Metal Oxide Semiconductor) process; the core just occupies a 28.5 × 22 μm² area. The measured phase noise is −108.45 dBc/Hz at a 1 MHz offset with a center frequency of 540 MHz. The gain of the oscillator is 0.309 MHz/mV with a control voltage from 0 V to 1.1 V. The circuit can work with a supply voltage as low as 1.2 V and the power consumption is only 0.46 mW at a 1.8 V supply voltage. Full article

(This article belongs to the Special Issue Smart Sensor Interface Circuits and Systems)

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16 pages, 614 KiB

Open AccessArticle

Cluster-Based Maximum Consensus Time Synchronization for Industrial Wireless Sensor Networks

by Zhaowei Wang^1,2, Peng Zeng^1,*, Mingtuo Zhou^3,4, Dong Li¹ and Jintao Wang^1,2

¹ Key Laboratory of Networked Control System, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China

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

³ Key Laboratory of Wireless Sensor Network & Communication, Shanghai Institute of Microsystem Information and Technology, Chinese Academy of Sciences, Shanghai 200050, China

⁴ Shanghai Research Center for Wireless Communications, Shanghai 201210, China

Sensors 2017, 17(1), 141; https://doi.org/10.3390/s17010141 - 13 Jan 2017

Cited by 38 | Viewed by 6596

Abstract

Time synchronization is one of the key technologies in Industrial Wireless Sensor Networks (IWSNs), and clustering is widely used in WSNs for data fusion and information collection to reduce redundant data and communication overhead. Considering IWSNs’ demand for low energy consumption, fast convergence, [...] Read more.

Time synchronization is one of the key technologies in Industrial Wireless Sensor Networks (IWSNs), and clustering is widely used in WSNs for data fusion and information collection to reduce redundant data and communication overhead. Considering IWSNs’ demand for low energy consumption, fast convergence, and robustness, this paper presents a novel Cluster-based Maximum consensus Time Synchronization (CMTS) method. It consists of two parts: intra-cluster time synchronization and inter-cluster time synchronization. Based on the theory of distributed consensus, the proposed method utilizes the maximum consensus approach to realize the intra-cluster time synchronization, and adjacent clusters exchange the time messages via overlapping nodes to synchronize with each other. A Revised-CMTS is further proposed to counteract the impact of bounded communication delays between two connected nodes, because the traditional stochastic models of the communication delays would distort in a dynamic environment. The simulation results show that our method reduces the communication overhead and improves the convergence rate in comparison to existing works, as well as adapting to the uncertain bounded communication delays. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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15 pages, 4959 KiB

Open AccessArticle

Nonlinear Fusion of Multispectral Citrus Fruit Image Data with Information Contents

by Peilin Li¹, Sang-Heon Lee¹

, Hung-Yao Hsu¹ and Jae-Sam Park^2,*

¹ School of Engineering, University of South Australia, Mawson Lakes 5095, Australia

² Department of Electronics Engineering, Incheon National University, 119 Academy Road, Yeon Su Gu, Incheon 22012, Korea

Sensors 2017, 17(1), 142; https://doi.org/10.3390/s17010142 - 13 Jan 2017

Cited by 9 | Viewed by 6575

Abstract

The main issue of vison-based automatic harvesting manipulators is the difficulty in the correct fruit identification in the images under natural lighting conditions. Mostly, the solution has been based on a linear combination of color components in the multispectral images. However, the results [...] Read more.

The main issue of vison-based automatic harvesting manipulators is the difficulty in the correct fruit identification in the images under natural lighting conditions. Mostly, the solution has been based on a linear combination of color components in the multispectral images. However, the results have not reached a satisfactory level. To overcome this issue, this paper proposes a robust nonlinear fusion method to augment the original color image with the synchronized near infrared image. The two images are fused with Daubechies wavelet transform (DWT) in a multiscale decomposition approach. With DWT, the background noises are reduced and the necessary image features are enhanced by fusing the color contrast of the color components and the homogeneity of the near infrared (NIR) component. The resulting fused color image is classified with a C-means algorithm for reconstruction. The performance of the proposed approach is evaluated with the statistical F measure in comparison to some existing methods using linear combinations of color components. The results show that the fusion of information in different spectral components has the advantage of enhancing the image quality, therefore improving the classification accuracy in citrus fruit identification in natural lighting conditions. Full article

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

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18 pages, 3330 KiB

Open AccessArticle

A Non-Intrusive Cyber Physical Social Sensing Solution to People Behavior Tracking: Mechanism, Prototype, and Field Experiments

by Yunjian Jia^1,*, Zhenyu Zhou^2,*

, Fei Chen¹, Peng Duan¹, Zhen Guo³ and Shahid Mumtaz⁴

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

² School of Electrical and Electronic Engineering, North China Electric Power University, Beijing 102206, China

³ Guoxin Tendering Group Co., Ltd., Beijing 100044, China

⁴ Instituto de Telecomunicações, Campus Universitário de Santiago, Aveiro 3810-193, Portugal

Sensors 2017, 17(1), 143; https://doi.org/10.3390/s17010143 - 13 Jan 2017

Cited by 7 | Viewed by 5554

Abstract

Tracking people’s behaviors is a main category of cyber physical social sensing (CPSS)-related people-centric applications. Most tracking methods utilize camera networks or sensors built into mobile devices such as global positioning system (GPS) and Bluetooth. In this article, we propose a non-intrusive wireless [...] Read more.

Tracking people’s behaviors is a main category of cyber physical social sensing (CPSS)-related people-centric applications. Most tracking methods utilize camera networks or sensors built into mobile devices such as global positioning system (GPS) and Bluetooth. In this article, we propose a non-intrusive wireless fidelity (Wi-Fi)-based tracking method. To show the feasibility, we target tracking people’s access behaviors in Wi-Fi networks, which has drawn a lot of interest from the academy and industry recently. Existing methods used for acquiring access traces either provide very limited visibility into media access control (MAC)-level transmission dynamics or sometimes are inflexible and costly. In this article, we present a passive CPSS system operating in a non-intrusive, flexible, and simplified manner to overcome above limitations. We have implemented the prototype on the off-the-shelf personal computer, and performed real-world deployment experiments. The experimental results show that the method is feasible, and people’s access behaviors can be correctly tracked within a one-second delay. Full article

(This article belongs to the Special Issue New Paradigms in Cyber-Physical Social Sensing)

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11 pages, 1613 KiB

Open AccessArticle

Reagent-Less and Robust Biosensor for Direct Determination of Lactate in Food Samples

by Iria Bravo^1,2, Mónica Revenga-Parra^1,2,3, Félix Pariente^1,3 and Encarnación Lorenzo^1,2,3,*

¹ Departamento de Química Analítica y Análisis Instrumental, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain

² Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Faraday, 9, Campus UAM, Cantoblanco, 28049 Madrid, Spain

³ Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain

Sensors 2017, 17(1), 144; https://doi.org/10.3390/s17010144 - 13 Jan 2017

Cited by 39 | Viewed by 8193

Abstract

Lactic acid is a relevant analyte in the food industry, since it affects the flavor, freshness, and storage quality of several products, such as milk and dairy products, juices, or wines. It is the product of lactose or malo-lactic fermentation. In this work, [...] Read more.

Lactic acid is a relevant analyte in the food industry, since it affects the flavor, freshness, and storage quality of several products, such as milk and dairy products, juices, or wines. It is the product of lactose or malo-lactic fermentation. In this work, we developed a lactate biosensor based on the immobilization of lactate oxidase (LOx) onto N,N′-Bis(3,4-dihydroxybenzylidene) -1,2-diaminobenzene Schiff base tetradentate ligand-modified gold nanoparticles (3,4DHS–AuNPs) deposited onto screen-printed carbon electrodes, which exhibit a potent electrocatalytic effect towards hydrogen peroxide oxidation/reduction. 3,4DHS–AuNPs were synthesized within a unique reaction step, in which 3,4DHS acts as reducing/capping/modifier agent for the generation of stable colloidal suspensions of Schiff base ligand–AuNPs assemblies of controlled size. The ligand—in addition to its reduction action—provides a robust coating to gold nanoparticles and a catalytic function. Lactate oxidase (LOx) catalyzes the conversion of l-lactate to pyruvate in the presence of oxygen, producing hydrogen peroxide, which is catalytically oxidized at 3,4DHS–AuNPs modified screen-printed carbon electrodes at +0.2 V. The measured electrocatalytic current is directly proportional to the concentration of peroxide, which is related to the amount of lactate present in the sample. The developed biosensor shows a detection limit of 2.6 μM lactate and a sensitivity of 5.1 ± 0.1 μA·mM⁻¹. The utility of the device has been demonstrated by the determination of the lactate content in different matrixes (white wine, beer, and yogurt). The obtained results compare well to those obtained using a standard enzymatic-spectrophotometric assay kit. Full article

(This article belongs to the Special Issue Recent Advances in Biosensors Based Screen Printed Platforms)

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10 pages, 1950 KiB

Open AccessArticle

Detection of the Vascular Endothelial Growth Factor with a Novel Bioluminescence Resonance Energy Transfer Pair Using a Two-Component System

by Tobias Wimmer, Eva Schroeter, Birgit Lorenz and Knut Stieger^*

Department of Ophthalmology, Justus-Liebig-University Giessen, Friedrichstr. 18, 35390 Giessen, Germany

Sensors 2017, 17(1), 145; https://doi.org/10.3390/s17010145 - 13 Jan 2017

Cited by 6 | Viewed by 5471

Abstract

In this paper we describe a two-component BRET (bioluminescence resonance energy transfer)-based method to detect vascular endothelial growth factor (VEGF) molecules in unknown samples as the basis for subsequent in vivo use. A luminescent VEGF binding molecule, which binds in the receptor binding [...] Read more.

In this paper we describe a two-component BRET (bioluminescence resonance energy transfer)-based method to detect vascular endothelial growth factor (VEGF) molecules in unknown samples as the basis for subsequent in vivo use. A luminescent VEGF binding molecule, which binds in the receptor binding motif of VEGF, is used as the energy donor, transferred to a fluorophore-coupled VEGF binding molecule (acceptor), which binds to the neuropilin binding motif of VEGF, thus enabling energy transfer from the donor to the acceptor molecule. This leads to the emission of light at a longer wavelength and thus the generation of an increased BRET signal only when VEGF is bound to both the donor and acceptor molecules. We further describe a novel BRET pair that uses the Renilla reniformis mutant luciferase RLuc8 and the chemically engineered fluorophore PerCP-Cy5.5^®, which exhibits superior peak separation of approximately 300 nm. The implantation of capsules consisting of the two BRET components in solution, permeable for VEGF for its in vivo detection, would provide a new and improved method for monitoring VEGF-induced pathologies and thus an adjustment of therapy to patient needs. Full article

(This article belongs to the Special Issue Colorimetric and Fluorescent Sensor)

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23 pages, 10213 KiB

Open AccessArticle

Continuous Space Estimation: Increasing WiFi-Based Indoor Localization Resolution without Increasing the Site-Survey Effort

by Noelia Hernández^1,*

, Manuel Ocaña²

, Jose M. Alonso³

and Euntai Kim⁴

¹ Intelligent Systems Laboratory, Department of Systems Engineering and Automation, Universidad Carlos III de Madrid, 28911 Leganés, Madrid, Spain

² Robesafe Research Group, Department of Electronics, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid, Spain

³ Centro Singular de Investigacion en Tecnoloxias da Informacion (CiTIUS), Universidade de Santiago de Compostela, Campus Vida, E-15782, Santiago de Compostela, Galicia, Spain

⁴ Computational Intelligence Lab, School of Electrical and Electronic Engineering, Yonsei University, 03722 Seoul, Korea

Sensors 2017, 17(1), 147; https://doi.org/10.3390/s17010147 - 13 Jan 2017

Cited by 75 | Viewed by 9764

Abstract

Although much research has taken place in WiFi indoor localization systems, their accuracy can still be improved. When designing this kind of system, fingerprint-based methods are a common choice. The problem with fingerprint-based methods comes with the need of site surveying the environment, [...] Read more.

Although much research has taken place in WiFi indoor localization systems, their accuracy can still be improved. When designing this kind of system, fingerprint-based methods are a common choice. The problem with fingerprint-based methods comes with the need of site surveying the environment, which is effort consuming. In this work, we propose an approach, based on support vector regression, to estimate the received signal strength at non-site-surveyed positions of the environment. Experiments, performed in a real environment, show that the proposed method could be used to improve the resolution of fingerprint-based indoor WiFi localization systems without increasing the site survey effort. Full article

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

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15 pages, 9274 KiB

Open AccessArticle

Throughput Measurement of a Dual-Band MIMO Rectangular Dielectric Resonator Antenna for LTE Applications

by Jamal Nasir^1,2

, Mohd. Haizal Jamaluddin^1,*, Aftab Ahmad Khan², Muhammad Ramlee Kamarudin¹, Chee Yen Leow¹ and Owais Owais²

¹ Wireless Communication Centre, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia

² Department of Electrical Engineering, COMSATS Institute of Information Technology, 22060 Abbottabad, Pakistan

Sensors 2017, 17(1), 148; https://doi.org/10.3390/s17010148 - 13 Jan 2017

Cited by 21 | Viewed by 8066

Abstract

An L-shaped dual-band multiple-input multiple-output (MIMO) rectangular dielectric resonator antenna (RDRA) for long term evolution (LTE) applications is proposed. The presented antenna can transmit and receive information independently using fundamental TE₁₁₁ and higher order TE₁₂₁ modes of the DRA. TE₁₁₁ [...] Read more.

An L-shaped dual-band multiple-input multiple-output (MIMO) rectangular dielectric resonator antenna (RDRA) for long term evolution (LTE) applications is proposed. The presented antenna can transmit and receive information independently using fundamental TE₁₁₁ and higher order TE₁₂₁ modes of the DRA. TE₁₁₁ degenerate mode covers LTE band 2 (1.85–1.99 GHz), 3 (1.71–1.88 GHz), and 9 (1.7499–1.7849 GHz) at f_r = 1.8 GHz whereas TE₁₂₁ covers LTE band 7 (2.5–2.69 GHz) at f_r = 2.6 GHz, respectively. An efficient design method has been used to reduce mutual coupling between ports by changing the effective permittivity values of DRA by introducing a cylindrical air-gap at an optimal position in the dielectric resonator. This air-gap along with matching strips at the corners of the dielectric resonator keeps the isolation at a value more than 17 dB at both the bands. The diversity performance has also been evaluated by calculating the envelope correlation coefficient, diversity gain, and mean effective gain of the proposed design. MIMO performance has been evaluated by measuring the throughput of the proposed MIMO antenna. Experimental results successfully validate the presented design methodology in this work. Full article

(This article belongs to the Section Sensor Networks)

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11 pages, 2911 KiB

Open AccessArticle

Learning to Diagnose Cirrhosis with Liver Capsule Guided Ultrasound Image Classification

by Xiang Liu^1,2, Jia Lin Song³, Shuo Hong Wang¹, Jing Wen Zhao¹ and Yan Qiu Chen^1,*

¹ School of Computer Science, Shanghai Key Laboratory of Intelligent Information Processing, Fudan University, Shanghai 201203, China

² School of Electronic and Electrical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China

³ Department of ultrasound, Changzheng Hospital Affiliated to Second Military Medical University, Shanghai 200003, China

Sensors 2017, 17(1), 149; https://doi.org/10.3390/s17010149 - 13 Jan 2017

Cited by 102 | Viewed by 12933

Abstract

This paper proposes a computer-aided cirrhosis diagnosis system to diagnose cirrhosis based on ultrasound images. We first propose a method to extract a liver capsule on an ultrasound image, then, based on the extracted liver capsule, we fine-tune a deep convolutional neural network [...] Read more.

This paper proposes a computer-aided cirrhosis diagnosis system to diagnose cirrhosis based on ultrasound images. We first propose a method to extract a liver capsule on an ultrasound image, then, based on the extracted liver capsule, we fine-tune a deep convolutional neural network (CNN) model to extract features from the image patches cropped around the liver capsules. Finally, a trained support vector machine (SVM) classifier is applied to classify the sample into normal or abnormal cases. Experimental results show that the proposed method can effectively extract the liver capsules and accurately classify the ultrasound images. Full article

(This article belongs to the Section Physical Sensors)

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34 pages, 1764 KiB

Open AccessArticle

A Study on Coexistence Capability Evaluations of the Enhanced Channel Hopping Mechanism in WBANs

by Zhongcheng Wei, Yongmei Sun^* and Yuefeng Ji

State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications (BUPT), No. 10 Xitucheng Road, Haidian District, Beijing 100876, China

Sensors 2017, 17(1), 151; https://doi.org/10.3390/s17010151 - 14 Jan 2017

Cited by 4 | Viewed by 4260

Abstract

As an important coexistence technology, channel hopping can reduce the interference among Wireless Body Area Networks (WBANs). However, it simultaneously brings some issues, such as energy waste, long latency and communication interruptions, etc. In this paper, we propose an enhanced channel hopping mechanism [...] Read more.

As an important coexistence technology, channel hopping can reduce the interference among Wireless Body Area Networks (WBANs). However, it simultaneously brings some issues, such as energy waste, long latency and communication interruptions, etc. In this paper, we propose an enhanced channel hopping mechanism that allows multiple WBANs coexisted in the same channel. In order to evaluate the coexistence performance, some critical metrics are designed to reflect the possibility of channel conflict. Furthermore, by taking the queuing and non-queuing behaviors into consideration, we present a set of analysis approaches to evaluate the coexistence capability. On the one hand, we present both service-dependent and service-independent analysis models to estimate the number of coexisting WBANs. On the other hand, based on the uniform distribution assumption and the additive property of Possion-stream, we put forward two approximate methods to compute the number of occupied channels. Extensive simulation results demonstrate that our estimation approaches can provide an effective solution for coexistence capability estimation. Moreover, the enhanced channel hopping mechanism can significantly improve the coexistence capability and support a larger arrival rate of WBANs. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 1911 KiB

Open AccessArticle

Rapid Transfer Alignment of MEMS SINS Based on Adaptive Incremental Kalman Filter

by Hairong Chu¹, Tingting Sun^1,*, Baiqiang Zhang^1,2

, Hongwei Zhang¹ and Yang Chen¹

¹ Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China

² University of Chinese Academy of Sciences, Beijing 10049, China

Sensors 2017, 17(1), 152; https://doi.org/10.3390/s17010152 - 14 Jan 2017

Cited by 23 | Viewed by 5576

Abstract

In airborne MEMS SINS transfer alignment, the error of MEMS IMU is highly environment-dependent and the parameters of the system model are also uncertain, which may lead to large error and bad convergence of the Kalman filter. In order to solve this problem, [...] Read more.

In airborne MEMS SINS transfer alignment, the error of MEMS IMU is highly environment-dependent and the parameters of the system model are also uncertain, which may lead to large error and bad convergence of the Kalman filter. In order to solve this problem, an improved adaptive incremental Kalman filter (AIKF) algorithm is proposed. First, the model of SINS transfer alignment is defined based on the “Velocity and Attitude” matching method. Then the detailed algorithm progress of AIKF and its recurrence formulas are presented. The performance and calculation amount of AKF and AIKF are also compared. Finally, a simulation test is designed to verify the accuracy and the rapidity of the AIKF algorithm by comparing it with KF and AKF. The results show that the AIKF algorithm has better estimation accuracy and shorter convergence time, especially for the bias of the gyroscope and the accelerometer, which can meet the accuracy and rapidity requirement of transfer alignment. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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15 pages, 6776 KiB

Open AccessArticle

Application of Fault Tree Analysis and Fuzzy Neural Networks to Fault Diagnosis in the Internet of Things (IoT) for Aquaculture

by Yingyi Chen^1,2,3,*

, Zhumi Zhen^1,2,3, Huihui Yu^1,2,3 and Jing Xu^1,2,3

¹ College of Information and Electrical Engineering, China Agricultural University, Beijing 100083, China

² Key Laboratory of Agricultural Information Acquisition Technology, Ministry of Agriculture, Beijing 100083, China

³ Beijing Engineering and Technology Research Centre for Internet of Things in Agriculture, Beijing 100083, China

Sensors 2017, 17(1), 153; https://doi.org/10.3390/s17010153 - 14 Jan 2017

Cited by 65 | Viewed by 12770

Abstract

In the Internet of Things (IoT) equipment used for aquaculture is often deployed in outdoor ponds located in remote areas. Faults occur frequently in these tough environments and the staff generally lack professional knowledge and pay a low degree of attention in these [...] Read more.

In the Internet of Things (IoT) equipment used for aquaculture is often deployed in outdoor ponds located in remote areas. Faults occur frequently in these tough environments and the staff generally lack professional knowledge and pay a low degree of attention in these areas. Once faults happen, expert personnel must carry out maintenance outdoors. Therefore, this study presents an intelligent method for fault diagnosis based on fault tree analysis and a fuzzy neural network. In the proposed method, first, the fault tree presents a logic structure of fault symptoms and faults. Second, rules extracted from the fault trees avoid duplicate and redundancy. Third, the fuzzy neural network is applied to train the relationship mapping between fault symptoms and faults. In the aquaculture IoT, one fault can cause various fault symptoms, and one symptom can be caused by a variety of faults. Four fault relationships are obtained. Results show that one symptom-to-one fault, two symptoms-to-two faults, and two symptoms-to-one fault relationships can be rapidly diagnosed with high precision, while one symptom-to-two faults patterns perform not so well, but are still worth researching. This model implements diagnosis for most kinds of faults in the aquaculture IoT. Full article

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

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31 pages, 515 KiB

Open AccessArticle

Bulk Data Dissemination in Low Power Sensor Networks: Present and Future Directions

by Zhirong Xu^1,*, Tianlei Hu^1,* and Qianshu Song²

¹ Collge of Computer Science, Zhejiang University, Zhejiang 310027, China

² Zhejiang Association for Science and Technology, Zhejiang 310003, China

Sensors 2017, 17(1), 156; https://doi.org/10.3390/s17010156 - 14 Jan 2017

Cited by 3 | Viewed by 5536

Abstract

Wireless sensor network-based (WSN-based) applications need an efficient and reliable data dissemination service to facilitate maintenance, management and data distribution tasks. As WSNs nowadays are becoming pervasive and data intensive, bulk data dissemination protocols have been extensively studied recently. This paper provides a [...] Read more.

Wireless sensor network-based (WSN-based) applications need an efficient and reliable data dissemination service to facilitate maintenance, management and data distribution tasks. As WSNs nowadays are becoming pervasive and data intensive, bulk data dissemination protocols have been extensively studied recently. This paper provides a comprehensive survey of the state-of-the-art bulk data dissemination protocols. The large number of papers available in the literature propose various techniques to optimize the dissemination protocols. Different from the existing survey works which separately explores the building blocks of dissemination, our work categorizes the literature according to the optimization purposes: Reliability, Scalability and Transmission/Energy efficiency. By summarizing and reviewing the key insights and techniques, we further discuss on the future directions for each category. Our survey helps unveil three key findings for future direction: (1) The recent advances in wireless communications (e.g., study on cross-technology interference, error estimating codes, constructive interference, capture effect) can be potentially exploited to support further optimization on the reliability and energy efficiency of dissemination protocols; (2) Dissemination in multi-channel, multi-task and opportunistic networks requires more efforts to fully exploit the spatial-temporal network resources to enhance the data propagation; (3) Since many designs incur changes on MAC layer protocols, the co-existence of dissemination with other network protocols is another problem left to be addressed. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 3933 KiB

Open AccessArticle

Fabrication of a Miniature Multi-Parameter Sensor Chip for Water Quality Assessment

by Bo Zhou^1,2, Chao Bian^1,*, Jianhua Tong¹ and Shanhong Xia¹

¹ State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China

² School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100080, China

Sensors 2017, 17(1), 157; https://doi.org/10.3390/s17010157 - 14 Jan 2017

Cited by 45 | Viewed by 9697

Abstract

Water contamination is a main inducement of human diseases. It is an important step to monitor the water quality in the water distribution system. Due to the features of large size, high cost, and complicated structure of traditional water determination sensors and devices, [...] Read more.

Water contamination is a main inducement of human diseases. It is an important step to monitor the water quality in the water distribution system. Due to the features of large size, high cost, and complicated structure of traditional water determination sensors and devices, it is difficult to realize real-time water monitoring on a large scale. In this paper, we present a multi-parameter sensor chip, which is miniature, low-cost, and robust, to detect the pH, conductivity, and temperature of water simultaneously. The sensor chip was fabricated using micro-electro-mechanical system (MEMS) techniques. Iridium oxide film was electrodeposited as the pH-sensing material. The atomic ratio of Ir(III) to Ir(IV) is about 1.38 according to the X-ray photoelectron spectroscopy (XPS) analysis. The pH sensing electrode showed super-Nernstian response (−67.60 mV/pH) and good linearity (R² = 0.9997), in the range of pH 2.22 to pH 11.81. KCl-agar and epoxy were used as the electrolyte layer and liquid junction for the solid-state reference electrode, respectively, and its potential stability in deionized water was 56 h. The conductivity cell exhibited a linear determination range from 21.43

μ S / cm

to 1.99

mS / cm

, and the electrode constant was 1.566 cm⁻¹. Sensitivity of the temperature sensor was 5.46

Ω / ° C

. The results indicate that the developed sensor chip has potential application in water quality measurements. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 1970 KiB

Open AccessArticle

A Fast Multimodal Ectopic Beat Detection Method Applied for Blood Pressure Estimation Based on Pulse Wave Velocity Measurements in Wearable Sensors

by Maik Pflugradt^1,†, Kai Geissdoerfer^1,†, Matthias Goernig² and Reinhold Orglmeister^1,*

¹ Chair of Electronics and Medical Signal Processing, TU Berlin, 10623 Berlin, Germany

² Staedtisches Klinikum Dresden-Neustadt, 01159 Dresden, Germany

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 158; https://doi.org/10.3390/s17010158 - 14 Jan 2017

Cited by 17 | Viewed by 9298

Abstract

Automatic detection of ectopic beats has become a thoroughly researched topic, with literature providing manifold proposals typically incorporating morphological analysis of the electrocardiogram (ECG). Although being well understood, its utilization is often neglected, especially in practical monitoring situations like online evaluation of signals [...] Read more.

Automatic detection of ectopic beats has become a thoroughly researched topic, with literature providing manifold proposals typically incorporating morphological analysis of the electrocardiogram (ECG). Although being well understood, its utilization is often neglected, especially in practical monitoring situations like online evaluation of signals acquired in wearable sensors. Continuous blood pressure estimation based on pulse wave velocity considerations is a prominent example, which depends on careful fiducial point extraction and is therefore seriously affected during periods of increased occurring extrasystoles. In the scope of this work, a novel ectopic beat discriminator with low computational complexity has been developed, which takes advantage of multimodal features derived from ECG and pulse wave relating measurements, thereby providing additional information on the underlying cardiac activity. Moreover, the blood pressure estimations’ vulnerability towards ectopic beats is closely examined on records drawn from the Physionet database as well as signals recorded in a small field study conducted in a geriatric facility for the elderly. It turns out that a reliable extrasystole identification is essential to unsupervised blood pressure estimation, having a significant impact on the overall accuracy. The proposed method further convinces by its applicability to battery driven hardware systems with limited processing power and is a favorable choice when access to multimodal signal features is given anyway. Full article

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

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29 pages, 12592 KiB

Open AccessArticle

Opportunistic Sensor Data Collection with Bluetooth Low Energy

by Sergio Aguilar, Rafael Vidal^†

and Carles Gomez^*,†

¹ Universitat Politècnica de Catalunya/Fundació i2Cat, C/Esteve Terradas, 7, 08860 Castelldefels, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 159; https://doi.org/10.3390/s17010159 - 23 Jan 2017

Cited by 62 | Viewed by 10816

Abstract

Bluetooth Low Energy (BLE) has gained very high momentum, as witnessed by its widespread presence in smartphones, wearables and other consumer electronics devices. This fact can be leveraged to carry out opportunistic sensor data collection (OSDC) in scenarios where a sensor node cannot [...] Read more.

Bluetooth Low Energy (BLE) has gained very high momentum, as witnessed by its widespread presence in smartphones, wearables and other consumer electronics devices. This fact can be leveraged to carry out opportunistic sensor data collection (OSDC) in scenarios where a sensor node cannot communicate with infrastructure nodes. In such cases, a mobile entity (e.g., a pedestrian or a vehicle) equipped with a BLE-enabled device can collect the data obtained by the sensor node when both are within direct communication range. In this paper, we characterize, both analytically and experimentally, the performance and trade-offs of BLE as a technology for OSDC, for the two main identified approaches, and considering the impact of its most crucial configuration parameters. Results show that a BLE sensor node running on a coin cell battery can achieve a lifetime beyond one year while transferring around 10 Mbit/day, in realistic OSDC scenarios. Full article

(This article belongs to the Section Sensor Networks)

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26 pages, 5045 KiB

Open AccessArticle

Localization-Free Detection of Replica Node Attacks in Wireless Sensor Networks Using Similarity Estimation with Group Deployment Knowledge

by Chao Ding¹, Lijun Yang^2,* and Meng Wu^3,*

¹ College of Computer Science, Nanjing University of Posts and Telecommunications; Nanjing 210003, China

² College of Internet of Things, Nanjing University of Posts and Telecommunications; Nanjing 210003, China

³ Key Lab of “Broadband Wireless Communication and Sensor Network Technology” of Ministry of Education, Nanjing University of Posts and Telecommunications; Nanjing 210003, China

Sensors 2017, 17(1), 160; https://doi.org/10.3390/s17010160 - 15 Jan 2017

Cited by 12 | Viewed by 4500

Abstract

Due to the unattended nature and poor security guarantee of the wireless sensor networks (WSNs), adversaries can easily make replicas of compromised nodes, and place them throughout the network to launch various types of attacks. Such an attack is dangerous because it enables [...] Read more.

Due to the unattended nature and poor security guarantee of the wireless sensor networks (WSNs), adversaries can easily make replicas of compromised nodes, and place them throughout the network to launch various types of attacks. Such an attack is dangerous because it enables the adversaries to control large numbers of nodes and extend the damage of attacks to most of the network with quite limited cost. To stop the node replica attack, we propose a location similarity-based detection scheme using deployment knowledge. Compared with prior solutions, our scheme provides extra functionalities that prevent replicas from generating false location claims without deploying resource-consuming localization techniques on the resource-constraint sensor nodes. We evaluate the security performance of our proposal under different attack strategies through heuristic analysis, and show that our scheme achieves secure and robust replica detection by increasing the cost of node replication. Additionally, we evaluate the impact of network environment on the proposed scheme through theoretic analysis and simulation experiments, and indicate that our scheme achieves effectiveness and efficiency with substantially lower communication, computational, and storage overhead than prior works under different situations and attack strategies. Full article

(This article belongs to the Section Sensor Networks)

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11 pages, 455 KiB

Open AccessArticle

Continuous Glucose Monitoring Enables the Detection of Losses in Infusion Set Actuation (LISAs)

by Daniel P. Howsmon¹

, Faye Cameron¹, Nihat Baysal¹, Trang T. Ly^2,†, Gregory P. Forlenza³, David M. Maahs^3,‡, Bruce A. Buckingham², Juergen Hahn^1,4

and B. Wayne Bequette^1,*

¹ Department of Chemical & Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA

² Stanford University School of Medicine, Stanford, CA 94305, USA

³ Barbara Davis Center for Childhood Diabetes, University of Colorado Denver, Aurora, CO 80045, USA

⁴ Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA

^† Current address: Insulet Corporation, Billerica, MA 01821, USA

^‡ Current address: Stanford University School of Medicine, Stanford, CA 94305, USA

Sensors 2017, 17(1), 161; https://doi.org/10.3390/s17010161 - 15 Jan 2017

Cited by 21 | Viewed by 7085

Abstract

Reliable continuous glucose monitoring (CGM) enables a variety of advanced technology for the treatment of type 1 diabetes. In addition to artificial pancreas algorithms that use CGM to automate continuous subcutaneous insulin infusion (CSII), CGM can also inform fault detection algorithms that alert [...] Read more.

Reliable continuous glucose monitoring (CGM) enables a variety of advanced technology for the treatment of type 1 diabetes. In addition to artificial pancreas algorithms that use CGM to automate continuous subcutaneous insulin infusion (CSII), CGM can also inform fault detection algorithms that alert patients to problems in CGM or CSII. Losses in infusion set actuation (LISAs) can adversely affect clinical outcomes, resulting in hyperglycemia due to impaired insulin delivery. Prolonged hyperglycemia may lead to diabetic ketoacidosis—a serious metabolic complication in type 1 diabetes. Therefore, an algorithm for the detection of LISAs based on CGM and CSII signals was developed to improve patient safety. The LISA detection algorithm is trained retrospectively on data from 62 infusion set insertions from 20 patients. The algorithm collects glucose and insulin data, and computes relevant fault metrics over two different sliding windows; an alarm sounds when these fault metrics are exceeded. With the chosen algorithm parameters, the LISA detection strategy achieved a sensitivity of 71.8% and issued 0.28 false positives per day on the training data. Validation on two independent data sets confirmed that similar performance is seen on data that was not used for training. The developed algorithm is able to effectively alert patients to possible infusion set failures in open-loop scenarios, with limited evidence of its extension to closed-loop scenarios. Full article

(This article belongs to the Special Issue Glucose Sensors: Revolution in Diabetes Management 2016)

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13 pages, 4820 KiB

Open AccessArticle

Compressed Sensing Techniques Applied to Ultrasonic Imaging of Cargo Containers

by Yuri Álvarez López¹

and José Ángel Martínez Lorenzo^2,*

¹ Área de Teoría de la Señal y Comunicaciones, Universidad de Oviedo, Gijón (Asturias) 33203, Spain

² Departments of Mechanical & Industrial Engineering and Electrical & Computer Engineering, Northeastern University, Boston, MA 02115, USA

Sensors 2017, 17(1), 162; https://doi.org/10.3390/s17010162 - 15 Jan 2017

Cited by 3 | Viewed by 6298

Abstract

One of the key issues in the fight against the smuggling of goods has been the development of scanners for cargo inspection. X-ray-based radiographic system scanners are the most developed sensing modality. However, they are costly and use bulky sources that emit hazardous, [...] Read more.

One of the key issues in the fight against the smuggling of goods has been the development of scanners for cargo inspection. X-ray-based radiographic system scanners are the most developed sensing modality. However, they are costly and use bulky sources that emit hazardous, ionizing radiation. Aiming to improve the probability of threat detection, an ultrasonic-based technique, capable of detecting the footprint of metallic containers or compartments concealed within the metallic structure of the inspected cargo, has been proposed. The system consists of an array of acoustic transceivers that is attached to the metallic structure-under-inspection, creating a guided acoustic Lamb wave. Reflections due to discontinuities are detected in the images, provided by an imaging algorithm. Taking into consideration that the majority of those images are sparse, this contribution analyzes the application of Compressed Sensing (CS) techniques in order to reduce the amount of measurements needed, thus achieving faster scanning, without compromising the detection capabilities of the system. A parametric study of the image quality, as a function of the samples needed in spatial and frequency domains, is presented, as well as the dependence on the sampling pattern. For this purpose, realistic cargo inspection scenarios have been simulated. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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11 pages, 1771 KiB

Open AccessArticle

Modulation Index Adjustment for Recovery of Pure Wavelength Modulation Spectroscopy Second Harmonic Signal Waveforms

by Wei Wei

, Jun Chang^*, Qiang Wang and Zengguang Qin

School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan 250100, China

Sensors 2017, 17(1), 163; https://doi.org/10.3390/s17010163 - 15 Jan 2017

Cited by 10 | Viewed by 6866

Abstract

A new technique of modulation index adjustment for pure wavelength modulation spectroscopy second harmonic signal waveforms recovery is presented. As the modulation index is a key parameter in determining the exact form of the signals generated by the technique of wavelength modulation spectroscopy, [...] Read more.

A new technique of modulation index adjustment for pure wavelength modulation spectroscopy second harmonic signal waveforms recovery is presented. As the modulation index is a key parameter in determining the exact form of the signals generated by the technique of wavelength modulation spectroscopy, the method of modulation index adjustment is applied to recover the second harmonic signal with wavelength modulation spectroscopy. By comparing the measured profile with the theoretical profile by calculation, the relationship between the modulation index and average quantities of the scanning wavelength can be obtained. Furthermore, when the relationship is applied in the experimental setup by point-by-point modulation index modification for gas detection, the results show good agreement with the theoretical profile and signal waveform distortion (such as the amplitude modulation effect caused by diode laser) can be suppressed. Besides, the method of modulation index adjustment can be used in many other aspects which involve profile improvement. In practical applications, when the amplitude modulation effect can be neglected and the stability of the detection system is limited by the sampling rate of analog-to-digital, modulation index adjustment can be used to improve detection into softer inflection points and solve the insufficient sampling problem. As a result, measurement stability is improved by 40%. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 5383 KiB

Open AccessArticle

Modeling and Calibration of a Novel One-Mirror Galvanometric Laser Scanner

by Chengyi Yu¹, Xiaobo Chen¹ and Juntong Xi^1,2,*

¹ State Key Laboratory of Mechanical System and Vibration, Shanghai Jiaotong University, Shanghai 200240, China

² Shanghai Key Laboratory of Advanced Manufacturing Environment, Shanghai 200030, China

Sensors 2017, 17(1), 164; https://doi.org/10.3390/s17010164 - 15 Jan 2017

Cited by 51 | Viewed by 8942

Abstract

A laser stripe sensor has limited application when a point cloud of geometric samples on the surface of the object needs to be collected, so a galvanometric laser scanner is designed by using a one-mirror galvanometer element as its mechanical device to drive [...] Read more.

A laser stripe sensor has limited application when a point cloud of geometric samples on the surface of the object needs to be collected, so a galvanometric laser scanner is designed by using a one-mirror galvanometer element as its mechanical device to drive the laser stripe to sweep along the object. A novel mathematical model is derived for the proposed galvanometer laser scanner without any position assumptions and then a model-driven calibration procedure is proposed. Compared with available model-driven approaches, the influence of machining and assembly errors is considered in the proposed model. Meanwhile, a plane-constraint-based approach is proposed to extract a large number of calibration points effectively and accurately to calibrate the galvanometric laser scanner. Repeatability and accuracy of the galvanometric laser scanner are evaluated on the automobile production line to verify the efficiency and accuracy of the proposed calibration method. Experimental results show that the proposed calibration approach yields similar measurement performance compared with a look-up table calibration method. Full article

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

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20 pages, 12991 KiB

Open AccessArticle

Tracking and Classification of In-Air Hand Gesture Based on Thermal Guided Joint Filter

by Seongwan Kim

, Yuseok Ban and Sangyoun Lee^*

Department of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea

Sensors 2017, 17(1), 166; https://doi.org/10.3390/s17010166 - 17 Jan 2017

Cited by 17 | Viewed by 6568

Abstract

The research on hand gestures has attracted many image processing-related studies, as it intuitively conveys the intention of a human as it pertains to motional meaning. Various sensors have been used to exploit the advantages of different modalities for the extraction of important [...] Read more.

The research on hand gestures has attracted many image processing-related studies, as it intuitively conveys the intention of a human as it pertains to motional meaning. Various sensors have been used to exploit the advantages of different modalities for the extraction of important information conveyed by the hand gesture of a user. Although many works have focused on learning the benefits of thermal information from thermal cameras, most have focused on face recognition or human body detection, rather than hand gesture recognition. Additionally, the majority of the works that take advantage of multiple modalities (e.g., the combination of a thermal sensor and a visual sensor), usually adopting simple fusion approaches between the two modalities. As both thermal sensors and visual sensors have their own shortcomings and strengths, we propose a novel joint filter-based hand gesture recognition method to simultaneously exploit the strengths and compensate the shortcomings of each. Our study is motivated by the investigation of the mutual supplementation between thermal and visual information in low feature level for the consistent representation of a hand in the presence of varying lighting conditions. Accordingly, our proposed method leverages the thermal sensor’s stability against luminance and the visual sensors textural detail, while complementing the low resolution and halo effect of thermal sensors and the weakness against illumination of visual sensors. A conventional region tracking method and a deep convolutional neural network have been leveraged to track the trajectory of a hand gesture and to recognize the hand gesture, respectively. Our experimental results show stability in recognizing a hand gesture against varying lighting conditions based on the contribution of the joint kernels of spatial adjacency and thermal range similarity. Full article

(This article belongs to the Special Issue Human Detection, Identification, and Recognition of Gesture and Behavior based on Thermal Camera)

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13 pages, 1377 KiB

Open AccessArticle

Local Observability Analysis of Star Sensor Installation Errors in a SINS/CNS Integration System for Near-Earth Flight Vehicles

by Yanqiang Yang, Chunxi Zhang and Jiazhen Lu^*

The Science and Technology on Inertial Laboratory, School of Instrumentation Science and Opto-electronics Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191, China

Sensors 2017, 17(1), 167; https://doi.org/10.3390/s17010167 - 16 Jan 2017

Cited by 33 | Viewed by 4461

Abstract

Strapdown inertial navigation system/celestial navigation system (SINS/CNS) integrated navigation is a fully autonomous and high precision method, which has been widely used to improve the hitting accuracy and quick reaction capability of near-Earth flight vehicles. The installation errors between SINS and star sensors [...] Read more.

Strapdown inertial navigation system/celestial navigation system (SINS/CNS) integrated navigation is a fully autonomous and high precision method, which has been widely used to improve the hitting accuracy and quick reaction capability of near-Earth flight vehicles. The installation errors between SINS and star sensors have been one of the main factors that restrict the actual accuracy of SINS/CNS. In this paper, an integration algorithm based on the star vector observations is derived considering the star sensor installation error. Then, the star sensor installation error is accurately estimated based on Kalman Filtering (KF). Meanwhile, a local observability analysis is performed on the rank of observability matrix obtained via linearization observation equation, and the observable conditions are presented and validated. The number of star vectors should be greater than or equal to 2, and the times of posture adjustment also should be greater than or equal to 2. Simulations indicate that the star sensor installation error could be readily observable based on the maneuvering condition; moreover, the attitude errors of SINS are less than 7 arc-seconds. This analysis method and conclusion are useful in the ballistic trajectory design of near-Earth flight vehicles. Full article

(This article belongs to the Section Physical Sensors)

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25 pages, 1187 KiB

Open AccessArticle

A Novel IEEE 802.15.4e DSME MAC for Wireless Sensor Networks

by Prasan Kumar Sahoo^1,3

, Sudhir Ranjan Pattanaik² and Shih-Lin Wu^1,3,4,*

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

² Department of Electrical Engineering, Chang Gung University, Taoyuan 33302, Taiwan

³ Department of Cardiology, Chang Gung Memorial Hospital, Taoyuan 33305, Taiwan

⁴ Department of Electrical Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan

Sensors 2017, 17(1), 168; https://doi.org/10.3390/s17010168 - 16 Jan 2017

Cited by 31 | Viewed by 5728

Abstract

IEEE 802.15.4e standard proposes Deterministic and Synchronous Multichannel Extension (DSME) mode for wireless sensor networks (WSNs) to support industrial, commercial and health care applications. In this paper, a new channel access scheme and beacon scheduling schemes are designed for the IEEE 802.15.4e enabled [...] Read more.

IEEE 802.15.4e standard proposes Deterministic and Synchronous Multichannel Extension (DSME) mode for wireless sensor networks (WSNs) to support industrial, commercial and health care applications. In this paper, a new channel access scheme and beacon scheduling schemes are designed for the IEEE 802.15.4e enabled WSNs in star topology to reduce the network discovery time and energy consumption. In addition, a new dynamic guaranteed retransmission slot allocation scheme is designed for devices with the failure Guaranteed Time Slot (GTS) transmission to reduce the retransmission delay. To evaluate our schemes, analytical models are designed to analyze the performance of WSNs in terms of reliability, delay, throughput and energy consumption. Our schemes are validated with simulation and analytical results and are observed that simulation results well match with the analytical one. The evaluated results of our designed schemes can improve the reliability, throughput, delay, and energy consumptions significantly. Full article

(This article belongs to the Section Sensor Networks)

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15 pages, 3280 KiB

Open AccessArticle

An Improved High-Sensitivity Airborne Transient Electromagnetic Sensor for Deep Penetration

by Shudong Chen¹, Shuxu Guo¹, Haofeng Wang¹, Miao He¹, Xiaoyan Liu¹, Yu Qiu¹, Shuang Zhang^1,*, Zhiwen Yuan², Haiyang Zhang², Dong Fang² and Jun Zhu^2,*

¹ College of Electronic Science and Engineering, Jilin University, Changchun 130012, China

² Science and Technology on Near-Surface Detection Laboratory, Wuxi 214035, China

Sensors 2017, 17(1), 169; https://doi.org/10.3390/s17010169 - 17 Jan 2017

Cited by 11 | Viewed by 5284

Abstract

The investigation depth of transient electromagnetic sensors can be effectively increased by reducing the system noise, which is mainly composed of sensor internal noise, electromagnetic interference (EMI), and environmental noise, etc. A high-sensitivity airborne transient electromagnetic (AEM) sensor with low sensor internal noise [...] Read more.

The investigation depth of transient electromagnetic sensors can be effectively increased by reducing the system noise, which is mainly composed of sensor internal noise, electromagnetic interference (EMI), and environmental noise, etc. A high-sensitivity airborne transient electromagnetic (AEM) sensor with low sensor internal noise and good shielding effectiveness is of great importance for deep penetration. In this article, the design and optimization of such an AEM sensor is described in detail. To reduce sensor internal noise, a noise model with both a damping resistor and a preamplifier is established and analyzed. The results indicate that a sensor with a large diameter, low resonant frequency, and low sampling rate will have lower sensor internal noise. To improve the electromagnetic compatibility of the sensor, an electromagnetic shielding model for a central-tapped coil is established and discussed in detail. Previous studies have shown that unclosed shields with multiple layers and center grounding can effectively suppress EMI and eddy currents. According to these studies, an improved differential AEM sensor is constructed with a diameter, resultant effective area, resonant frequency, and normalized equivalent input noise of 1.1 m, 114 m², 35.6 kHz, and 13.3 nV/m², respectively. The accuracy of the noise model and the shielding effectiveness of the sensor have been verified experimentally. The results show a good agreement between calculated and measured results for the sensor internal noise. Additionally, over 20 dB shielding effectiveness is achieved in a complex electromagnetic environment. All of these results show a great improvement in sensor internal noise and shielding effectiveness. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 3373 KiB

Open AccessArticle

Design of Wearable Breathing Sound Monitoring System for Real-Time Wheeze Detection

by Shih-Hong Li^1,5, Bor-Shing Lin²

, Chen-Han Tsai³, Cheng-Ta Yang^4,5 and Bor-Shyh Lin^3,*

¹ Department of Thoracic Medicine, Chang Gung Memorial Hospital at Linkou, Taoyuan 33305, Taiwan

² Department of Computer Science and Information Engineering, National Taipei University, New Taipei City 23741, Taiwan

³ Institute of Imaging and Biomedical Photonics, National Chiao Tung University, Tainan 71150, Taiwan

⁴ Department of Thoracic Medicine, Chang Gung Memorial Hospital at Taoyuan, Taoyuan 33378, Taiwan

⁵ Department of Respiratory Therapy, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan

Sensors 2017, 17(1), 171; https://doi.org/10.3390/s17010171 - 17 Jan 2017

Cited by 106 | Viewed by 13827

Abstract

In the clinic, the wheezing sound is usually considered as an indicator symptom to reflect the degree of airway obstruction. The auscultation approach is the most common way to diagnose wheezing sounds, but it subjectively depends on the experience of the physician. Several [...] Read more.

In the clinic, the wheezing sound is usually considered as an indicator symptom to reflect the degree of airway obstruction. The auscultation approach is the most common way to diagnose wheezing sounds, but it subjectively depends on the experience of the physician. Several previous studies attempted to extract the features of breathing sounds to detect wheezing sounds automatically. However, there is still a lack of suitable monitoring systems for real-time wheeze detection in daily life. In this study, a wearable and wireless breathing sound monitoring system for real-time wheeze detection was proposed. Moreover, a breathing sounds analysis algorithm was designed to continuously extract and analyze the features of breathing sounds to provide the objectively quantitative information of breathing sounds to professional physicians. Here, normalized spectral integration (NSI) was also designed and applied in wheeze detection. The proposed algorithm required only short-term data of breathing sounds and lower computational complexity to perform real-time wheeze detection, and is suitable to be implemented in a commercial portable device, which contains relatively low computing power and memory. From the experimental results, the proposed system could provide good performance on wheeze detection exactly and might be a useful assisting tool for analysis of breathing sounds in clinical diagnosis. Full article

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

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19 pages, 3847 KiB

Open AccessArticle

Development of a GNSS Buoy for Monitoring Water Surface Elevations in Estuaries and Coastal Areas

by Yen-Pin Lin¹, Ching-Jer Huang^1,*, Sheng-Hsueh Chen², Dong-Jiing Doong¹ and Chia Chuen Kao¹

¹ Department of Hydraulic and Ocean Engineering, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan

² Coastal Ocean Monitoring Center, National Cheng Kung University, No. 1, University Road, Tainan 701, Taiwan

Sensors 2017, 17(1), 172; https://doi.org/10.3390/s17010172 - 18 Jan 2017

Cited by 24 | Viewed by 8037

Abstract

In this work, a Global Navigation Satellite System (GNSS) buoy that utilizes a Virtual Base Station (VBS) combined with the Real-Time Kinematic (RTK) positioning technology was developed to monitor water surface elevations in estuaries and coastal areas. The GNSS buoy includes a buoy [...] Read more.

In this work, a Global Navigation Satellite System (GNSS) buoy that utilizes a Virtual Base Station (VBS) combined with the Real-Time Kinematic (RTK) positioning technology was developed to monitor water surface elevations in estuaries and coastal areas. The GNSS buoy includes a buoy hull, a RTK GNSS receiver, data-transmission devices, a data logger, and General Purpose Radio Service (GPRS) modems for transmitting data to the desired land locations. Laboratory and field tests were conducted to test the capability of the buoy and verify the accuracy of the monitored water surface elevations. For the field tests, the GNSS buoy was deployed in the waters of Suao (northeastern part of Taiwan). Tide data obtained from the GNSS buoy were consistent with those obtained from the neighboring tide station. Significant wave heights, zero-crossing periods, and peak wave directions obtained from the GNSS buoy were generally consistent with those obtained from an accelerometer-tilt-compass (ATC) sensor. The field tests demonstrate that the developed GNSS buoy can be used to obtain accurate real-time tide and wave data in estuaries and coastal areas. Full article

(This article belongs to the Section Remote Sensors)

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10 pages, 3880 KiB

Open AccessArticle

Two-Dimensional Numerical Simulations of Ultrasound in Liquids with Gas Bubble Agglomerates: Examples of Bubbly-Liquid-Type Acoustic Metamaterials (BLAMMs)

by Christian Vanhille

NANLA, ESCET, Universidad Rey Juan Carlos, 28933 Móstoles, Madrid, Spain

Sensors 2017, 17(1), 173; https://doi.org/10.3390/s17010173 - 17 Jan 2017

Cited by 9 | Viewed by 5244

Abstract

This work deals with a theoretical analysis about the possibility of using linear and nonlinear acoustic properties to modify ultrasound by adding gas bubbles of determined sizes in a liquid. We use a two-dimensional numerical model to evaluate the effect that one and [...] Read more.

This work deals with a theoretical analysis about the possibility of using linear and nonlinear acoustic properties to modify ultrasound by adding gas bubbles of determined sizes in a liquid. We use a two-dimensional numerical model to evaluate the effect that one and several monodisperse bubble populations confined in restricted areas of a liquid have on ultrasound by calculating their nonlinear interaction. The filtering of an input ultrasonic pulse performed by a net of bubbly-liquid cells is analyzed. The generation of a low-frequency component from a single cell impinged by a two-frequency harmonic wave is also studied. These effects rely on the particular dispersive character of attenuation and nonlinearity of such bubbly fluids, which can be extremely high near bubble resonance. They allow us to observe how gas bubbles can change acoustic signals. Variations of the bubbly medium parameters induce alterations of the effects undergone by ultrasound. Results suggest that acoustic signals can be manipulated by bubbles. This capacity to achieve the modification and control of sound with oscillating gas bubbles introduces the concept of bubbly-liquid-based acoustic metamaterials (BLAMMs). Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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27 pages, 8441 KiB

Open AccessArticle

Effective Alternating Direction Optimization Methods for Sparsity-Constrained Blind Image Deblurring

by Naixue Xiong^1,2

, Ryan Wen Liu^1,*

, Maohan Liang¹, Di Wu³, Zhao Liu^1,* and Huisi Wu⁴

¹ Hubei Key Laboratory of Inland Shipping Technology, School of Navigation, Wuhan University of Technology, Wuhan 430063, China

² Department of Business and Computer Science, Southwestern Oklahoma State University, Oklahoma, OK 73096, USA

³ School of Computer, Wuhan University, Wuhan 430072, China

⁴ College of Computer Science and Software Engineering, Shenzhen University, Shenzhen 518060, China

Sensors 2017, 17(1), 174; https://doi.org/10.3390/s17010174 - 18 Jan 2017

Cited by 37 | Viewed by 7381

Abstract

Single-image blind deblurring for imaging sensors in the Internet of Things (IoT) is a challenging ill-conditioned inverse problem, which requires regularization techniques to stabilize the image restoration process. The purpose is to recover the underlying blur kernel and latent sharp image from only [...] Read more.

Single-image blind deblurring for imaging sensors in the Internet of Things (IoT) is a challenging ill-conditioned inverse problem, which requires regularization techniques to stabilize the image restoration process. The purpose is to recover the underlying blur kernel and latent sharp image from only one blurred image. Under many degraded imaging conditions, the blur kernel could be considered not only spatially sparse, but also piecewise smooth with the support of a continuous curve. By taking advantage of the hybrid sparse properties of the blur kernel, a hybrid regularization method is proposed in this paper to robustly and accurately estimate the blur kernel. The effectiveness of the proposed blur kernel estimation method is enhanced by incorporating both the

L_{1}

-norm of kernel intensity and the squared

L_{2}

-norm of the intensity derivative. Once the accurate estimation of the blur kernel is obtained, the original blind deblurring can be simplified to the direct deconvolution of blurred images. To guarantee robust non-blind deconvolution, a variational image restoration model is presented based on the

L_{1}

-norm data-fidelity term and the total generalized variation (TGV) regularizer of second-order. All non-smooth optimization problems related to blur kernel estimation and non-blind deconvolution are effectively handled by using the alternating direction method of multipliers (ADMM)-based numerical methods. Comprehensive experiments on both synthetic and realistic datasets have been implemented to compare the proposed method with several state-of-the-art methods. The experimental comparisons have illustrated the satisfactory imaging performance of the proposed method in terms of quantitative and qualitative evaluations. Full article

(This article belongs to the Special Issue Topology Control in Emerging Sensor Networks)

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15 pages, 1577 KiB

Open AccessArticle

Opportunistic Capacity-Based Resource Allocation for Chunk-Based Multi-Carrier Cognitive Radio Sensor Networks

by Jie Huang, Xiaoping Zeng, Xin Jian^*, Xiaoheng Tan and Qi Zhang

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

Sensors 2017, 17(1), 175; https://doi.org/10.3390/s17010175 - 18 Jan 2017

Cited by 6 | Viewed by 4016

Abstract

The spectrum allocation for cognitive radio sensor networks (CRSNs) has received considerable research attention under the assumption that the spectrum environment is static. However, in practice, the spectrum environment varies over time due to primary user/secondary user (PU/SU) activity and mobility, resulting in [...] Read more.

The spectrum allocation for cognitive radio sensor networks (CRSNs) has received considerable research attention under the assumption that the spectrum environment is static. However, in practice, the spectrum environment varies over time due to primary user/secondary user (PU/SU) activity and mobility, resulting in time-varied spectrum resources. This paper studies resource allocation for chunk-based multi-carrier CRSNs with time-varied spectrum resources. We present a novel opportunistic capacity model through a continuous time semi-Markov chain (CTSMC) to describe the time-varied spectrum resources of chunks and, based on this, a joint power and chunk allocation model by considering the opportunistically available capacity of chunks is proposed. To reduce the computational complexity, we split this model into two sub-problems and solve them via the Lagrangian dual method. Simulation results illustrate that the proposed opportunistic capacity-based resource allocation algorithm can achieve better performance compared with traditional algorithms when the spectrum environment is time-varied. Full article

(This article belongs to the Section Sensor Networks)

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24 pages, 8575 KiB

Open AccessArticle

PlaIMoS: A Remote Mobile Healthcare Platform to Monitor Cardiovascular and Respiratory Variables

by Ramses Miramontes^1,*

, Raúl Aquino²

, Arturo Flores¹, Guillermo Rodríguez¹

, Rafael Anguiano¹

, Arturo Ríos¹ and Arthur Edwards²

¹ Department of Innovation and Technological Development, Rasoft S.A. de C.V., 111 Canario Street, C.P. 28017 Colima, Col., Mexico

² College of Telematics, University of Colima, 333 University Avenue, C.P. 28045 Colima, Col., Mexico

Sensors 2017, 17(1), 176; https://doi.org/10.3390/s17010176 - 19 Jan 2017

Cited by 39 | Viewed by 11623

Abstract

The number of elderly and chronically ill patients has grown significantly over the past few decades as life expectancy has increased worldwide, leading to increased demands on the health care system and significantly taxing traditional health care practices. Consequently, there is an urgent [...] Read more.

The number of elderly and chronically ill patients has grown significantly over the past few decades as life expectancy has increased worldwide, leading to increased demands on the health care system and significantly taxing traditional health care practices. Consequently, there is an urgent need to use technology to innovate and more constantly and intensely monitor, report and analyze critical patient physiological parameters beyond conventional clinical settings in a more efficient and cost effective manner. This paper presents a technological platform called PlaIMoS which consists of wearable sensors, a fixed measurement station, a network infrastructure that employs IEEE 802.15.4 and IEEE 802.11 to transmit data with security mechanisms, a server to analyze all information collected and apps for iOS, Android and Windows 10 mobile operating systems to provide real-time measurements. The developed architecture, designed primarily to record and report electrocardiogram and heart rate data, also monitors parameters associated with chronic respiratory illnesses, including patient blood oxygen saturation and respiration rate, body temperature, fall detection and galvanic resistance. Full article

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

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15 pages, 4412 KiB

Open AccessArticle

UHF Signal Processing and Pattern Recognition of Partial Discharge in Gas-Insulated Switchgear Using Chromatic Methodology

by Xiaohua Wang¹, Xi Li^1,*, Mingzhe Rong^1,*, Dingli Xie¹, Dan Ding¹ and Zhixiang Wang^1,2

¹ State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China

² Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool L69 3GJ, UK

Sensors 2017, 17(1), 177; https://doi.org/10.3390/s17010177 - 18 Jan 2017

Cited by 29 | Viewed by 5800

Abstract

The ultra-high frequency (UHF) method is widely used in insulation condition assessment. However, UHF signal processing algorithms are complicated and the size of the result is large, which hinders extracting features and recognizing partial discharge (PD) patterns. This article investigated the chromatic methodology [...] Read more.

The ultra-high frequency (UHF) method is widely used in insulation condition assessment. However, UHF signal processing algorithms are complicated and the size of the result is large, which hinders extracting features and recognizing partial discharge (PD) patterns. This article investigated the chromatic methodology that is novel in PD detection. The principle of chromatic methodologies in color science are introduced. The chromatic processing represents UHF signals sparsely. The UHF signals obtained from PD experiments were processed using chromatic methodology and characterized by three parameters in chromatic space (H, L, and S representing dominant wavelength, signal strength, and saturation, respectively). The features of the UHF signals were studied hierarchically. The results showed that the chromatic parameters were consistent with conventional frequency domain parameters. The global chromatic parameters can be used to distinguish UHF signals acquired by different sensors, and they reveal the propagation properties of the UHF signal in the L-shaped gas-insulated switchgear (GIS). Finally, typical PD defect patterns had been recognized by using novel chromatic parameters in an actual GIS tank and good performance of recognition was achieved. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 23898 KiB

Open AccessArticle

A Differential Resonant Accelerometer with Low Cross-Interference and Temperature Drift

by Bo Li¹, Yulong Zhao^1,*, Cun Li¹, Rongjun Cheng¹, Dengqiang Sun¹ and Songli Wang²

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

² Aviation Key Laboratory of Science and Technology on Inertia, Flight Automatic Control Research Institute, Xi’an 710065, China

Sensors 2017, 17(1), 178; https://doi.org/10.3390/s17010178 - 18 Jan 2017

Cited by 26 | Viewed by 9502

Abstract

Presented in this paper is a high-performance resonant accelerometer with low cross-interference, low temperature drift and digital output. The sensor consists of two quartz double-ended tuning forks (DETFs) and a silicon substrate. A new differential silicon substrate is proposed to reduce the temperature [...] Read more.

Presented in this paper is a high-performance resonant accelerometer with low cross-interference, low temperature drift and digital output. The sensor consists of two quartz double-ended tuning forks (DETFs) and a silicon substrate. A new differential silicon substrate is proposed to reduce the temperature drift and cross-interference from the undesirable direction significantly. The natural frequency of the quartz DETF is theoretically calculated, and then the axial stress on the vibration beams is verified through finite element method (FEM) under a 100 g acceleration which is loaded on x-axis, y-axis and z-axis, respectively. Moreover, sensor chip is wire-bonded to a printed circuit board (PCB) which contains two identical oscillating circuits. In addition, a steel shell is selected to package the sensor for experiments. Benefiting from the distinctive configuration of the differential structure, the accelerometer characteristics such as temperature drift and cross-interface are improved. The experimental results demonstrate that the cross-interference is lower than 0.03% and the temperature drift is about 18.16 ppm/°C. Full article

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

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17 pages, 10617 KiB

Open AccessArticle

Hybrid Intelligent System to Perform Fault Detection on BIS Sensor During Surgeries

by José-Luis Casteleiro-Roca^1,*,†, José Luis Calvo-Rolle^1,*,†,‡

, Juan Albino Méndez Pérez^2,†

, Nieves Roqueñí Gutiérrez^3,† and Francisco Javier De Cos Juez^4,†

¹ Department of Industrial Engineering, Universidade da Coruña, 15405 Coruña, Spain

² Departamento de Ingeniería Informática y de Sistemas, Universidad de La Laguna, Apdo. 456; 38200 La Laguna, Spain

³ Project Engineering Area, Department of Exploitation and Exploration of Mines, University of Oviedo, 33004 Oviedo, Spain

⁴ Prospecting and Exploitation of Mines Department, University of Oviedo, 33004 Oviedo, Spain

^† These authors contributed equally to this work.

^‡ Current address: Department of Industrial Engineering, University of Coruña, 15405 Coruña, Spain.

Sensors 2017, 17(1), 179; https://doi.org/10.3390/s17010179 - 18 Jan 2017

Cited by 35 | Viewed by 11373

Abstract

This paper presents a new fault detection system in hypnotic sensors used for general anesthesia during surgery. Drug infusion during surgery is based on information received from patient monitoring devices; accordingly, faults in sensor devices can put patient safety at risk. Our research [...] Read more.

This paper presents a new fault detection system in hypnotic sensors used for general anesthesia during surgery. Drug infusion during surgery is based on information received from patient monitoring devices; accordingly, faults in sensor devices can put patient safety at risk. Our research offers a solution to cope with these undesirable scenarios. We focus on the anesthesia process using intravenous propofol as the hypnotic drug and employing a Bispectral Index (BIS^TM) monitor to estimate the patient’s unconsciousness level. The method developed identifies BIS episodes affected by disturbances during surgery with null clinical value. Thus, the clinician—or the automatic controller—will not take those measures into account to calculate the drug dose. Our method compares the measured BIS signal with expected behavior predicted by the propofol dose provider and the electromyogram (EMG) signal. For the prediction of the BIS signal, a model based on a hybrid intelligent system architecture has been created. The model uses clustering combined with regression techniques. To validate its accuracy, a dataset taken during surgeries with general anesthesia was used. The proposed fault detection method for BIS sensor measures has also been verified using data from real cases. The obtained results prove the method’s effectiveness. Full article

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

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19 pages, 5556 KiB

Open AccessArticle

Modeling Aboveground Biomass in Hulunber Grassland Ecosystem by Using Unmanned Aerial Vehicle Discrete Lidar

by Dongliang Wang^1,2, Xiaoping Xin^1,*, Quanqin Shao², Matthew Brolly³

, Zhiliang Zhu⁴ and Jin Chen⁵

¹ National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China

² Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Science, Beijing 100101, China

³ School of Environment and Technology, University of Brighton, Brighton BN2 4GJ, UK

⁴ U.S. Geological Survey, Reston, VA 20192, USA

⁵ State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China

Sensors 2017, 17(1), 180; https://doi.org/10.3390/s17010180 - 19 Jan 2017

Cited by 86 | Viewed by 9144

Abstract

Accurate canopy structure datasets, including canopy height and fractional cover, are required to monitor aboveground biomass as well as to provide validation data for satellite remote sensing products. In this study, the ability of an unmanned aerial vehicle (UAV) discrete light detection and [...] Read more.

Accurate canopy structure datasets, including canopy height and fractional cover, are required to monitor aboveground biomass as well as to provide validation data for satellite remote sensing products. In this study, the ability of an unmanned aerial vehicle (UAV) discrete light detection and ranging (lidar) was investigated for modeling both the canopy height and fractional cover in Hulunber grassland ecosystem. The extracted mean canopy height, maximum canopy height, and fractional cover were used to estimate the aboveground biomass. The influences of flight height on lidar estimates were also analyzed. The main findings are: (1) the lidar-derived mean canopy height is the most reasonable predictor of aboveground biomass (R² = 0.340, root-mean-square error (RMSE) = 81.89 g·m⁻², and relative error of 14.1%). The improvement of multiple regressions to the R² and RMSE values is unobvious when adding fractional cover in the regression since the correlation between mean canopy height and fractional cover is high; (2) Flight height has a pronounced effect on the derived fractional cover and details of the lidar data, but the effect is insignificant on the derived canopy height when the flight height is within the range (<100 m). These findings are helpful for modeling stable regressions to estimate grassland biomass using lidar returns. Full article

(This article belongs to the Special Issue Sensors and Smart Sensing of Agricultural Land Systems)

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19 pages, 3121 KiB

Open AccessArticle

Value-Based Caching in Information-Centric Wireless Body Area Networks

by Fadi M. Al-Turjman¹, Muhammad Imran^2,*

and Athanasios V. Vasilakos³

¹ Department of Computer Engineering, Middle East Technical University, Northern Cyprus Campus, 99738 Kalkanli, Güzelyurt, Mersin 10, Turkey

² College of Computer and Information Sciences, King Saud University, Riyadh 11543, Saudi Arabia

³ Department of Computer Science, Electrical and Space Engineering, Lulea University of Technology, Luleå 97187, Sweden

Sensors 2017, 17(1), 181; https://doi.org/10.3390/s17010181 - 19 Jan 2017

Cited by 22 | Viewed by 5657

Abstract

We propose a resilient cache replacement approach based on a Value of sensed Information (VoI) policy. To resolve and fetch content when the origin is not available due to isolated in-network nodes (fragmentation) and harsh operational conditions, we exploit a content caching approach. [...] Read more.

We propose a resilient cache replacement approach based on a Value of sensed Information (VoI) policy. To resolve and fetch content when the origin is not available due to isolated in-network nodes (fragmentation) and harsh operational conditions, we exploit a content caching approach. Our approach depends on four functional parameters in sensory Wireless Body Area Networks (WBANs). These four parameters are: age of data based on periodic request, popularity of on-demand requests, communication interference cost, and the duration for which the sensor node is required to operate in active mode to capture the sensed readings. These parameters are considered together to assign a value to the cached data to retain the most valuable information in the cache for prolonged time periods. The higher the value, the longer the duration for which the data will be retained in the cache. This caching strategy provides significant availability for most valuable and difficult to retrieve data in the WBANs. Extensive simulations are performed to compare the proposed scheme against other significant caching schemes in the literature while varying critical aspects in WBANs (e.g., data popularity, cache size, publisher load, connectivity-degree, and severe probabilities of node failures). These simulation results indicate that the proposed VoI-based approach is a valid tool for the retrieval of cached content in disruptive and challenging scenarios, such as the one experienced in WBANs, since it allows the retrieval of content for a long period even while experiencing severe in-network node failures. Full article

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

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30 pages, 1725 KiB

Open AccessArticle

SNR and Standard Deviation of cGNSS-R and iGNSS-R Scatterometric Measurements

by Alberto Alonso-Arroyo^1,2,*, Jorge Querol¹

, Carlos Lopez-Martinez¹, Valery U. Zavorotny², Hyuk Park¹

, Daniel Pascual¹

, Raul Onrubia¹

and Adriano Camps^1,*

¹ Department of Signal Theory and Communications, Universitat Politécnica de Catalunya—BarcelonaTech (UPC), 08034 Barcelona, Spain

² Earth System Research Laboratory (ERSL), National Oceanic and Atmospheric Administration (NOAA), Boulder, CO 80305-3337, USA

Sensors 2017, 17(1), 183; https://doi.org/10.3390/s17010183 - 19 Jan 2017

Cited by 9 | Viewed by 8177

Abstract

This work addresses the accuracy of the Global Navigation Satellite Systems (GNSS)-Reflectometry (GNSS-R) scatterometric measurements considering the presence of both coherent and incoherent scattered components, for both conventional GNSS-R (cGNSS-R) and interferometric GNSS-R (iGNSS-R) techniques. The coherent component is present for some type [...] Read more.

This work addresses the accuracy of the Global Navigation Satellite Systems (GNSS)-Reflectometry (GNSS-R) scatterometric measurements considering the presence of both coherent and incoherent scattered components, for both conventional GNSS-R (cGNSS-R) and interferometric GNSS-R (iGNSS-R) techniques. The coherent component is present for some type of surfaces, and it has been neglected until now because it vanishes for the sea surface scattering case. Taking into account the presence of both scattering components, the estimated Signal-to-Noise Ratio (SNR) for both techniques is computed based on the detectability criterion, as it is done in conventional GNSS applications. The non-coherent averaging operation is considered from a general point of view, taking into account that thermal noise contributions can be reduced by an extra factor of 0.88 dB when using partially overlapped or partially correlated samples. After the SNRs are derived, the received waveform’s peak variability is computed, which determines the system’s capability to measure geophysical parameters. This theoretical derivations are applied to the United Kingdom (UK) TechDemoSat-1 (UK TDS-1) and to the future GNSS REflectometry, Radio Occultation and Scatterometry on board the International Space Station (ISS) (GEROS-ISS) scenarios, in order to estimate the expected scatterometric performance of both missions. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 9259 KiB

Open AccessArticle

Euro Banknote Recognition System for Blind People

by Larisa Dunai Dunai^1,*

, Mónica Chillarón Pérez², Guillermo Peris-Fajarnés¹ and Ismael Lengua Lengua¹

¹ Research Center in Graphic Technology, Universitat Politècnica de València, Camino de Vera s/n, 5L, Valencia 46022, Spain

² Department DSIC, Universitat Politecnica de Valencia, Valencia 46022, Spain

Sensors 2017, 17(1), 184; https://doi.org/10.3390/s17010184 - 20 Jan 2017

Cited by 33 | Viewed by 12777

Abstract

This paper presents the development of a portable system with the aim of allowing blind people to detect and recognize Euro banknotes. The developed device is based on a Raspberry Pi electronic instrument and a Raspberry Pi camera, Pi NoIR (No Infrared filter) [...] Read more.

This paper presents the development of a portable system with the aim of allowing blind people to detect and recognize Euro banknotes. The developed device is based on a Raspberry Pi electronic instrument and a Raspberry Pi camera, Pi NoIR (No Infrared filter) dotted with additional infrared light, which is embedded into a pair of sunglasses that permit blind and visually impaired people to independently handle Euro banknotes, especially when receiving their cash back when shopping. The banknote detection is based on the modified Viola and Jones algorithms, while the banknote value recognition relies on the Speed Up Robust Features (SURF) technique. The accuracies of banknote detection and banknote value recognition are 84% and 97.5%, respectively. Full article

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

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13 pages, 3106 KiB

Open AccessArticle

A Liquid Level Measurement Technique Outside a Sealed Metal Container Based on Ultrasonic Impedance and Echo Energy

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

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

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

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

Sensors 2017, 17(1), 185; https://doi.org/10.3390/s17010185 - 19 Jan 2017

Cited by 26 | Viewed by 9459

Abstract

The proposed method for measuring the liquid level focuses on the ultrasonic impedance and echo energy inside a metal wall, to which the sensor is attached directly, not on ultrasonic waves that penetrate the gas–liquid medium of a container. Firstly, by analyzing the [...] Read more.

The proposed method for measuring the liquid level focuses on the ultrasonic impedance and echo energy inside a metal wall, to which the sensor is attached directly, not on ultrasonic waves that penetrate the gas–liquid medium of a container. Firstly, by analyzing the sound field distribution characteristics of the sensor in a metal wall, this paper proposes the concept of an "energy circle" and discusses how to calculate echo energy under three different states in detail. Meanwhile, an ultrasonic transmitting and receiving circuit is designed to convert the echo energy inside the energy circle into its equivalent electric power. Secondly, in order to find the two critical states of the energy circle in the process of liquid level detection, a program is designed to help with calculating two critical positions automatically. Finally, the proposed method is evaluated through a series of experiments, and the experimental results indicate that the proposed method is effective and accurate in calibration of the liquid level outside a sealed metal container. Full article

(This article belongs to the Special Issue Ultrasonic Sensors)

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26 pages, 3940 KiB

Open AccessArticle

A Distributed and Energy-Efficient Algorithm for Event K-Coverage in Underwater Sensor Networks

by Peng Jiang^*, Yiming Xu and Jun Liu

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

Sensors 2017, 17(1), 186; https://doi.org/10.3390/s17010186 - 19 Jan 2017

Cited by 11 | Viewed by 6655

Abstract

For event dynamic K-coverage algorithms, each management node selects its assistant node by using a greedy algorithm without considering the residual energy and situations in which a node is selected by several events. This approach affects network energy consumption and balance. Therefore, this [...] Read more.

For event dynamic K-coverage algorithms, each management node selects its assistant node by using a greedy algorithm without considering the residual energy and situations in which a node is selected by several events. This approach affects network energy consumption and balance. Therefore, this study proposes a distributed and energy-efficient event K-coverage algorithm (DEEKA). After the network achieves 1-coverage, the nodes that detect the same event compete for the event management node with the number of candidate nodes and the average residual energy, as well as the distance to the event. Second, each management node estimates the probability of its neighbor nodes’ being selected by the event it manages with the distance level, the residual energy level, and the number of dynamic coverage event of these nodes. Third, each management node establishes an optimization model that uses expectation energy consumption and the residual energy variance of its neighbor nodes and detects the performance of the events it manages as targets. Finally, each management node uses a constrained non-dominated sorting genetic algorithm (NSGA-II) to obtain the Pareto set of the model and the best strategy via technique for order preference by similarity to an ideal solution (TOPSIS). The algorithm first considers the effect of harsh underwater environments on information collection and transmission. It also considers the residual energy of a node and a situation in which the node is selected by several other events. Simulation results show that, unlike the on-demand variable sensing K-coverage algorithm, DEEKA balances and reduces network energy consumption, thereby prolonging the network’s best service quality and lifetime. Full article

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

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19 pages, 3976 KiB

Open AccessArticle

Significant Change Spotting for Periodic Human Motion Segmentation of Cleaning Tasks Using Wearable Sensors

by Kai-Chun Liu

and Chia-Tai Chan^*

Department of Biomedical Engineering, National Yang-Ming University, 155, Li-Nong Street, Section 2, Peitou, Taipei 11221, Taiwan

Sensors 2017, 17(1), 187; https://doi.org/10.3390/s17010187 - 19 Jan 2017

Cited by 10 | Viewed by 5293

Abstract

The proportion of the aging population is rapidly increasing around the world, which will cause stress on society and healthcare systems. In recent years, advances in technology have created new opportunities for automatic activities of daily living (ADL) monitoring to improve the quality [...] Read more.

The proportion of the aging population is rapidly increasing around the world, which will cause stress on society and healthcare systems. In recent years, advances in technology have created new opportunities for automatic activities of daily living (ADL) monitoring to improve the quality of life and provide adequate medical service for the elderly. Such automatic ADL monitoring requires reliable ADL information on a fine-grained level, especially for the status of interaction between body gestures and the environment in the real-world. In this work, we propose a significant change spotting mechanism for periodic human motion segmentation during cleaning task performance. A novel approach is proposed based on the search for a significant change of gestures, which can manage critical technical issues in activity recognition, such as continuous data segmentation, individual variance, and category ambiguity. Three typical machine learning classification algorithms are utilized for the identification of the significant change candidate, including a Support Vector Machine (SVM), k-Nearest Neighbors (kNN), and Naive Bayesian (NB) algorithm. Overall, the proposed approach achieves 96.41% in the F1-score by using the SVM classifier. The results show that the proposed approach can fulfill the requirement of fine-grained human motion segmentation for automatic ADL monitoring. Full article

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

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27 pages, 7129 KiB

Open AccessArticle

A Reinforcement Learning Model Equipped with Sensors for Generating Perception Patterns: Implementation of a Simulated Air Navigation System Using ADS-B (Automatic Dependent Surveillance-Broadcast) Technology

by Santiago Álvarez de Toledo¹, Aurea Anguera², José M. Barreiro¹

, Juan A. Lara^3,* and David Lizcano³

¹ Escuela Técnica Superior de Ingenieros Informáticos, Campus de Montegancedo, Technical University of Madrid (UPM), Boadilla del Monte, 28660 Madrid, Spain

² Escuela Técnica Superior de Ingeniería de Sistemas Informáticos, Technical University of Madrid (UPM), C/Alan Turing s/n (Ctra. de Valencia km. 7), 28031 Madrid, Spain

³ Escuela de Ciencias Técnicas e Ingeniería, Madrid Open University (MOU), Crta. de la Coruña km. 38.500, Vía de Servicio, 15, Collado Villalba, 28400 Madrid, Spain

Sensors 2017, 17(1), 188; https://doi.org/10.3390/s17010188 - 19 Jan 2017

Cited by 7 | Viewed by 7465

Abstract

Over the last few decades, a number of reinforcement learning techniques have emerged, and different reinforcement learning-based applications have proliferated. However, such techniques tend to specialize in a particular field. This is an obstacle to their generalization and extrapolation to other areas. Besides, [...] Read more.

Over the last few decades, a number of reinforcement learning techniques have emerged, and different reinforcement learning-based applications have proliferated. However, such techniques tend to specialize in a particular field. This is an obstacle to their generalization and extrapolation to other areas. Besides, neither the reward-punishment (r-p) learning process nor the convergence of results is fast and efficient enough. To address these obstacles, this research proposes a general reinforcement learning model. This model is independent of input and output types and based on general bioinspired principles that help to speed up the learning process. The model is composed of a perception module based on sensors whose specific perceptions are mapped as perception patterns. In this manner, similar perceptions (even if perceived at different positions in the environment) are accounted for by the same perception pattern. Additionally, the model includes a procedure that statistically associates perception-action pattern pairs depending on the positive or negative results output by executing the respective action in response to a particular perception during the learning process. To do this, the model is fitted with a mechanism that reacts positively or negatively to particular sensory stimuli in order to rate results. The model is supplemented by an action module that can be configured depending on the maneuverability of each specific agent. The model has been applied in the air navigation domain, a field with strong safety restrictions, which led us to implement a simulated system equipped with the proposed model. Accordingly, the perception sensors were based on Automatic Dependent Surveillance-Broadcast (ADS-B) technology, which is described in this paper. The results were quite satisfactory, and it outperformed traditional methods existing in the literature with respect to learning reliability and efficiency. Full article

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16 pages, 4502 KiB

Open AccessArticle

Underwater Electromagnetic Sensor Networks—Part I: Link Characterization

by Gara Quintana-Díaz^1,*, Pablo Mena-Rodríguez^1,2, Iván Pérez-Álvarez¹

, Eugenio Jiménez¹

, Blas-Pablo Dorta-Naranjo¹, Santiago Zazo², Marina Pérez², Eduardo Quevedo³

, Laura Cardona³ and J. Joaquín Hernández³

¹ Instituto para el Desarrollo Tecnológico y la Innovación en Comunicaciones (IDeTIC), Universidad de Las Palmas de Gran Canaria (ULPGC), 35017 Las Palmas, Spain

² Escuela Técnica Superior de Ingenieros de Telecomunicación (ETSIT) – C-303, Universidad Politécnica de Madrid (UPM), Av. Complutense 30, 28040 Madrid, Spain

³ Plataforma Oceánica de Canarias (PLOCAN), 35214 Telde, Spain

Sensors 2017, 17(1), 189; https://doi.org/10.3390/s17010189 - 19 Jan 2017

Cited by 18 | Viewed by 8539

Abstract

Underwater Wireless Sensor Networks (UWSNs) using electromagnetic (EM) technology in marine shallow waters are examined, not just for environmental monitoring but for further interesting applications. Particularly, the use of EM waves is reconsidered in shallow waters due to the benefits offered in this [...] Read more.

Underwater Wireless Sensor Networks (UWSNs) using electromagnetic (EM) technology in marine shallow waters are examined, not just for environmental monitoring but for further interesting applications. Particularly, the use of EM waves is reconsidered in shallow waters due to the benefits offered in this context, where acoustic and optical technologies have serious disadvantages. Sea water scenario is a harsh environment for radiocommunications, and there is no standard model for the underwater EM channel. The high conductivity of sea water, the effect of seabed and the surface make the behaviour of the channel hard to predict. This justifies the need of link characterization as the first step to approach the development of EM underwater sensor networks. To obtain a reliable link model, measurements and simulations are required. The measuring setup for this purpose is explained and described, as well as the procedures used. Several antennas have been designed and tested in low frequency bands. Agreement between attenuation measurements and simulations at different distances was analysed and made possible the validation of simulation setups and the design of different communications layers of the system. This leads to the second step of this work, where data and routing protocols for the sensor network are examined. Full article

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

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14 pages, 855 KiB

Open AccessArticle

A Low-Complexity Method for Two-Dimensional Direction-of-Arrival Estimation Using an L-Shaped Array

by Qing Wang¹, Hang Yang¹, Hua Chen^1,*, Yangyang Dong²

and Laihua Wang³

¹ School of Electrical and Information Engineering, Tianjin University, 92 Weijin Road, Tianjin 300072, China

² Key Laboratory of Electronic Information Countermeasure and Simulation Technology, Ministry of Education, Xidian University, Xi’an 710071, China

³ School of Software, Qufu Normal University, Qufu 273165, China

Sensors 2017, 17(1), 190; https://doi.org/10.3390/s17010190 - 19 Jan 2017

Cited by 24 | Viewed by 5734

Abstract

In this paper, a new low-complexity method for two-dimensional (2D) direction-of-arrival (DOA) estimation is proposed. Based on a cross-correlation matrix formed from the L-shaped array, the proposed algorithm obtains the automatic pairing elevation and azimuth angles without eigendecomposition, which can avoid high computational [...] Read more.

In this paper, a new low-complexity method for two-dimensional (2D) direction-of-arrival (DOA) estimation is proposed. Based on a cross-correlation matrix formed from the L-shaped array, the proposed algorithm obtains the automatic pairing elevation and azimuth angles without eigendecomposition, which can avoid high computational cost. In addition, the cross-correlation matrix eliminates the effect of noise, which can achieve better DOA performance. Then, the theoretical error of the algorithm is analyzed and the Cramer–Rao bound (CRB) for the direction of arrival estimation is derived . Simulation results demonstrate that, at low signal-to-noise ratios (SNRs) and with a small number of snapshots, in contrast to Tayem’s algorithm and Kikuchi’s algorithm, the proposed algorithm achieves better DOA performance with lower complexity, while, for Gu’s algorithm, the proposed algorithm has slightly inferior DOA performance but with significantly lower complexity. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 3201 KiB

Open AccessArticle

Au-Graphene Hybrid Plasmonic Nanostructure Sensor Based on Intensity Shift

by Raed Alharbi

, Mehrdad Irannejad^* and Mustafa Yavuz

Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada

Sensors 2017, 17(1), 191; https://doi.org/10.3390/s17010191 - 19 Jan 2017

Cited by 11 | Viewed by 7267

Abstract

Integrating plasmonic materials, like gold with a two-dimensional material (e.g., graphene) enhances the light-material interaction and, hence, plasmonic properties of the metallic nanostructure. A localized surface plasmon resonance sensor is an effective platform for biomarker detection. They offer a better bulk surface (local) [...] Read more.

Integrating plasmonic materials, like gold with a two-dimensional material (e.g., graphene) enhances the light-material interaction and, hence, plasmonic properties of the metallic nanostructure. A localized surface plasmon resonance sensor is an effective platform for biomarker detection. They offer a better bulk surface (local) sensitivity than a regular surface plasmon resonance (SPR) sensor; however, they suffer from a lower figure of merit compared to that one in a propagating surface plasmon resonance sensors. In this work, a decorated multilayer graphene film with an Au nanostructures was proposed as a liquid sensor. The results showed a significant improvement in the figure of merit compared with other reported localized surface plasmon resonance sensors. The maximum figure of merit and intensity sensitivity of 240 and 55 RIU⁻¹ (refractive index unit) at refractive index change of 0.001 were achieved which indicate the capability of the proposed sensor to detect a small change in concentration of liquids in the ng/mL level which is essential in early-stage cancer disease detection. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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16 pages, 2942 KiB

Open AccessArticle

Synthetic Aperture Radar Target Recognition with Feature Fusion Based on a Stacked Autoencoder

by Miao Kang¹, Kefeng Ji^1,*, Xiangguang Leng¹

, Xiangwei Xing² and Huanxin Zou¹

¹ School of Electronic Science and Engineering, National University of Defense Technology, Sanyi Avenue, Changsha 410073, China

² Beijing Institute of Remote Sensing Information, Beijing 100192, China

Sensors 2017, 17(1), 192; https://doi.org/10.3390/s17010192 - 20 Jan 2017

Cited by 112 | Viewed by 8708

Abstract

Feature extraction is a crucial step for any automatic target recognition process, especially in the interpretation of synthetic aperture radar (SAR) imagery. In order to obtain distinctive features, this paper proposes a feature fusion algorithm for SAR target recognition based on a stacked [...] Read more.

Feature extraction is a crucial step for any automatic target recognition process, especially in the interpretation of synthetic aperture radar (SAR) imagery. In order to obtain distinctive features, this paper proposes a feature fusion algorithm for SAR target recognition based on a stacked autoencoder (SAE). The detailed procedure presented in this paper can be summarized as follows: firstly, 23 baseline features and Three-Patch Local Binary Pattern (TPLBP) features are extracted. These features can describe the global and local aspects of the image with less redundancy and more complementarity, providing richer information for feature fusion. Secondly, an effective feature fusion network is designed. Baseline and TPLBP features are cascaded and fed into a SAE. Then, with an unsupervised learning algorithm, the SAE is pre-trained by greedy layer-wise training method. Capable of feature expression, SAE makes the fused features more distinguishable. Finally, the model is fine-tuned by a softmax classifier and applied to the classification of targets. 10-class SAR targets based on Moving and Stationary Target Acquisition and Recognition (MSTAR) dataset got a classification accuracy up to 95.43%, which verifies the effectiveness of the presented algorithm. Full article

(This article belongs to the Section Remote Sensors)

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24 pages, 11346 KiB

Open AccessArticle

Efficient Wideband Spectrum Sensing with Maximal Spectral Efficiency for LEO Mobile Satellite Systems

by Feilong Li

, Zhiqiang Li, Guangxia Li^*, Feihong Dong

and Wei Zhang

College of Communication Engineering, PLA University of Science and Technology, 88 Houbiaoying Rd., Nanjing 210007, China

Sensors 2017, 17(1), 193; https://doi.org/10.3390/s17010193 - 21 Jan 2017

Cited by 6 | Viewed by 5858

Abstract

The usable satellite spectrum is becoming scarce due to static spectrum allocation policies. Cognitive radio approaches have already demonstrated their potential towards spectral efficiency for providing more spectrum access opportunities to secondary user (SU) with sufficient protection to licensed primary user (PU). Hence, [...] Read more.

The usable satellite spectrum is becoming scarce due to static spectrum allocation policies. Cognitive radio approaches have already demonstrated their potential towards spectral efficiency for providing more spectrum access opportunities to secondary user (SU) with sufficient protection to licensed primary user (PU). Hence, recent scientific literature has been focused on the tradeoff between spectrum reuse and PU protection within narrowband spectrum sensing (SS) in terrestrial wireless sensing networks. However, those narrowband SS techniques investigated in the context of terrestrial CR may not be applicable for detecting wideband satellite signals. In this paper, we mainly investigate the problem of joint designing sensing time and hard fusion scheme to maximize SU spectral efficiency in the scenario of low earth orbit (LEO) mobile satellite services based on wideband spectrum sensing. Compressed detection model is established to prove that there indeed exists one optimal sensing time achieving maximal spectral efficiency. Moreover, we propose novel wideband cooperative spectrum sensing (CSS) framework where each SU reporting duration can be utilized for its following SU sensing. The sensing performance benefits from the novel CSS framework because the equivalent sensing time is extended by making full use of reporting slot. Furthermore, in respect of time-varying channel, the spatiotemporal CSS (ST-CSS) is presented to attain space and time diversity gain simultaneously under hard decision fusion rule. Computer simulations show that the optimal sensing settings algorithm of joint optimization of sensing time, hard fusion rule and scheduling strategy achieves significant improvement in spectral efficiency. Additionally, the novel ST-CSS scheme performs much higher spectral efficiency than that of general CSS framework. Full article

(This article belongs to the Section Sensor Networks)

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12 pages, 1776 KiB

Open AccessArticle

1-Butyl-3-Methylimidazolium Tetrafluoroborate Film as a Highly Selective Sensing Material for Non-Invasive Detection of Acetone Using a Quartz Crystal Microbalance

by Wenyan Tao^1,2, Peng Lin^1,*, Sili Liu³, Qingji Xie⁴, Shanming Ke¹ and Xierong Zeng^1,2,*

¹ Shenzhen Key Laboratory of Special Functional Materials & Shenzhen Engineering Laboratory for Advance Technology of Ceramics, College of Materials Science and Engineering, Shenzhen University, Shenzhen 510081, China

² Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China

³ Department of Biomedical Engineering, the Chinese University of Hong Kong, Shatin, Hong Kong 999077, China

⁴ College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410082, China

Sensors 2017, 17(1), 194; https://doi.org/10.3390/s17010194 - 20 Jan 2017

Cited by 19 | Viewed by 6072

Abstract

Breath acetone serves as a biomarker for diabetes. This article reports 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), a type of room temperature ionic liquid (RTIL), as a selective sensing material for acetone. The RTIL sensing layer was coated on a quartz crystal microbalance (QCM) [...] Read more.

Breath acetone serves as a biomarker for diabetes. This article reports 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), a type of room temperature ionic liquid (RTIL), as a selective sensing material for acetone. The RTIL sensing layer was coated on a quartz crystal microbalance (QCM) for detection. The sensing mechanism is based on a decrease in viscosity and density of the [bmim][BF₄] film due to the solubilization of acetone leading to a positive frequency shift in the QCM. Acetone was detected with a linear range from 7.05 to 750 ppmv. Sensitivity and limit of detection were found to be 3.49 Hz/ppmv and 5.0 ppmv, respectively. The [bmim][BF₄]-modified QCM sensor demonstrated anti-interference ability to commonly found volatile organic compounds in breath, e.g., isoprene, 1,2-pentadiene, d-limonene, and dl-limonene. This technology is useful for applications in non-invasive early diabetic diagnosis. Full article

(This article belongs to the Section Chemical Sensors)

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8 pages, 5432 KiB

Open AccessArticle

A Wide-Range Displacement Sensor Based on Plastic Fiber Macro-Bend Coupling

by Jia Liu^1,2

, Yulong Hou^1,*, Huixin Zhang¹, Pinggang Jia¹

, Shan Su¹, Guocheng Fang², Wenyi Liu^1,2 and Jijun Xiong^1,2

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

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

Sensors 2017, 17(1), 196; https://doi.org/10.3390/s17010196 - 20 Jan 2017

Cited by 19 | Viewed by 5708

Abstract

This paper proposes the strategy of fabricating an all fiber wide-range displacement sensor based on the macro-bend coupling effect which causes power transmission between two twisted bending plastic optical fibers (POF), where the coupling power changes with the bending radius of the fibers. [...] Read more.

This paper proposes the strategy of fabricating an all fiber wide-range displacement sensor based on the macro-bend coupling effect which causes power transmission between two twisted bending plastic optical fibers (POF), where the coupling power changes with the bending radius of the fibers. For the sensor, a structure of two twisted plastic fibers is designed with the experimental platform that we constructed. The influence of external temperature and displacement speed shifts are reported. The displacement sensor performance is the sensor test at different temperatures and speeds. The sensor was found to be satisfactory at both room temperature and 70 °C when the displacement is up to 140 mm. The output power is approximately linear to a displacement of 110 mm–140 mm under room temperature and 2 mm/s speed at 19.805 nW/mm sensitivity and 0.12 mm resolution. The simple structure of the sensor makes it reliable for other applications and further utilizations, promising a bright future. Full article

(This article belongs to the Section Physical Sensors)

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26 pages, 9399 KiB

Open AccessArticle

Entropy-Based Registration of Point Clouds Using Terrestrial Laser Scanning and Smartphone GPS

by Maolin Chen^1,*

, Siying Wang², Mingwei Wang¹, Youchuan Wan¹ and Peipei He³

¹ School of Remote Sensing and Information Engineering, Wuhan University, Wuhan 430079, China

² Jiangsu Hi-Target Marine Technology Co., Ltd., Nanjin 210032, China

³ School of Resources and Environment, North China University of Water Resources and Electric Power, Zhengzhou 450046, China

Sensors 2017, 17(1), 197; https://doi.org/10.3390/s17010197 - 20 Jan 2017

Cited by 11 | Viewed by 6390

Abstract

Automatic registration of terrestrial laser scanning point clouds is a crucial but unresolved topic that is of great interest in many domains. This study combines terrestrial laser scanner with a smartphone for the coarse registration of leveled point clouds with small roll and [...] Read more.

Automatic registration of terrestrial laser scanning point clouds is a crucial but unresolved topic that is of great interest in many domains. This study combines terrestrial laser scanner with a smartphone for the coarse registration of leveled point clouds with small roll and pitch angles and height differences, which is a novel sensor combination mode for terrestrial laser scanning. The approximate distance between two neighboring scan positions is firstly calculated with smartphone GPS coordinates. Then, 2D distribution entropy is used to measure the distribution coherence between the two scans and search for the optimal initial transformation parameters. To this end, we propose a method called Iterative Minimum Entropy (IME) to correct initial transformation parameters based on two criteria: the difference between the average and minimum entropy and the deviation from the minimum entropy to the expected entropy. Finally, the presented method is evaluated using two data sets that contain tens of millions of points from panoramic and non-panoramic, vegetation-dominated and building-dominated cases and can achieve high accuracy and efficiency. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 694 KiB

Open AccessArticle

SisFall: A Fall and Movement Dataset

by Angela Sucerquia, José David López^*

and Jesús Francisco Vargas-Bonilla

SISTEMIC, Facultad de Ingeniería, Universidad de Antiquia UDEA, Calle 70 No. 52-21, 1226 Medellín, Colombia

Sensors 2017, 17(1), 198; https://doi.org/10.3390/s17010198 - 20 Jan 2017

Cited by 397 | Viewed by 22911

Abstract

Research on fall and movement detection with wearable devices has witnessed promising growth. However, there are few publicly available datasets, all recorded with smartphones, which are insufficient for testing new proposals due to their absence of objective population, lack of performed activities, and [...] Read more.

Research on fall and movement detection with wearable devices has witnessed promising growth. However, there are few publicly available datasets, all recorded with smartphones, which are insufficient for testing new proposals due to their absence of objective population, lack of performed activities, and limited information. Here, we present a dataset of falls and activities of daily living (ADLs) acquired with a self-developed device composed of two types of accelerometer and one gyroscope. It consists of 19 ADLs and 15 fall types performed by 23 young adults, 15 ADL types performed by 14 healthy and independent participants over 62 years old, and data from one participant of 60 years old that performed all ADLs and falls. These activities were selected based on a survey and a literature analysis. We test the dataset with widely used feature extraction and a simple to implement threshold based classification, achieving up to 96% of accuracy in fall detection. An individual activity analysis demonstrates that most errors coincide in a few number of activities where new approaches could be focused. Finally, validation tests with elderly people significantly reduced the fall detection performance of the tested features. This validates findings of other authors and encourages developing new strategies with this new dataset as the benchmark. Full article

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

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7 pages, 9881 KiB

Open AccessArticle

Novel Isoprene Sensor for a Flu Virus Breath Monitor

by Pelagia-Irene Gouma^1,2,*, Lisheng Wang², Sanford R. Simon² and Milutin Stanacevic²

¹ Department of Materials Science & Engineering & IPPM-UTARI, University of Texas at Arlington, Arlington, TX 76019, USA

² Center for Nanomaterials and Sensor Development, State University of New York, Stony Brook, NY 11794, USA

Sensors 2017, 17(1), 199; https://doi.org/10.3390/s17010199 - 20 Jan 2017

Cited by 36 | Viewed by 22551

Abstract

A common feature of the inflammatory response in patients who have actually contracted influenza is the generation of a number of volatile products of the alveolar and airway epithelium. These products include a number of volatile organic compounds (VOCs) and nitric oxide (NO). [...] Read more.

A common feature of the inflammatory response in patients who have actually contracted influenza is the generation of a number of volatile products of the alveolar and airway epithelium. These products include a number of volatile organic compounds (VOCs) and nitric oxide (NO). These may be used as biomarkers to detect the disease. A portable 3-sensor array microsystem-based tool that can potentially detect flu infection biomarkers is described here. Whether used in connection with in-vitro cell culture studies or as a single exhale breathalyzer, this device may be used to provide a rapid and non-invasive screening method for flu and other virus-based epidemics. Full article

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

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11 pages, 7109 KiB

Open AccessArticle

A Lift-Off-Tolerant Magnetic Flux Leakage Testing Method for Drill Pipes at Wellhead

by Jianbo Wu¹, Hui Fang^1,*, Long Li², Jie Wang¹, Xiaoming Huang¹, Yihua Kang², Yanhua Sun² and Chaoqing Tang³

¹ School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065, China

² School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China

³ School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK

Sensors 2017, 17(1), 201; https://doi.org/10.3390/s17010201 - 21 Jan 2017

Cited by 34 | Viewed by 10140

Abstract

To meet the great needs for MFL (magnetic flux leakage) inspection of drill pipes at wellheads, a lift-off-tolerant MFL testing method is proposed and investigated in this paper. Firstly, a Helmholtz coil magnetization method and the whole MFL testing scheme are proposed. Then, [...] Read more.

To meet the great needs for MFL (magnetic flux leakage) inspection of drill pipes at wellheads, a lift-off-tolerant MFL testing method is proposed and investigated in this paper. Firstly, a Helmholtz coil magnetization method and the whole MFL testing scheme are proposed. Then, based on the magnetic field focusing effect of ferrite cores, a lift-off-tolerant MFL sensor is developed and tested. It shows high sensitivity at a lift-off distance of 5.0 mm. Further, the follow-up high repeatability MFL probing system is designed and manufactured, which was embedded with the developed sensors. It can track the swing movement of drill pipes and allow the pipe ends to pass smoothly. Finally, the developed system is employed in a drilling field for drill pipe inspection. Test results show that the proposed method can fulfill the requirements for drill pipe inspection at wellheads, which is of great importance in drill pipe safety. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 7094 KiB

Open AccessArticle

Ubiquitous Emergency Medical Service System Based on Wireless Biosensors, Traffic Information, and Wireless Communication Technologies: Development and Evaluation

by Tan-Hsu Tan¹, Munkhjargal Gochoo^1,*, Yung-Fu Chen^2,8

, Jin-Jia Hu¹, John Y. Chiang³, Ching-Su Chang⁴, Ming-Huei Lee⁵, Yung-Nian Hsu⁶ and Jiin-Chyr Hsu⁷

¹ Department of Electrical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

² Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taichung City 40601, Taiwan

³ Department of Computer Science and Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan

⁴ Department of Data & Broadband Maintenance Center, Chunghwa Telecom Hsinchu Business Group, Hsinchu City 300, Taiwan

⁵ Department of Urology, Feng Yuan Hospital, Ministry of Health and Welfare, Taichung 42055, Taiwan

⁶ Department of Family Medicine, Taichung Hospital, Ministry of Health and Welfare, Taichung 403, Taiwan

⁷ Department of Internal Medicine, Taipei Hospital, Ministry of Health and Welfare, New Taipei City 242-13, Taiwan

⁸ Department of Health Services Administration, China Medical University, Taichung 40402, Taiwan

Sensors 2017, 17(1), 202; https://doi.org/10.3390/s17010202 - 21 Jan 2017

Cited by 29 | Viewed by 9137

Abstract

This study presents a new ubiquitous emergency medical service system (UEMS) that consists of a ubiquitous tele-diagnosis interface and a traffic guiding subsystem. The UEMS addresses unresolved issues of emergency medical services by managing the sensor wires for eliminating inconvenience for both patients [...] Read more.

This study presents a new ubiquitous emergency medical service system (UEMS) that consists of a ubiquitous tele-diagnosis interface and a traffic guiding subsystem. The UEMS addresses unresolved issues of emergency medical services by managing the sensor wires for eliminating inconvenience for both patients and paramedics in an ambulance, providing ubiquitous accessibility of patients’ biosignals in remote areas where the ambulance cannot arrive directly, and offering availability of real-time traffic information which can make the ambulance reach the destination within the shortest time. In the proposed system, patient’s biosignals and real-time video, acquired by wireless biosensors and a webcam, can be simultaneously transmitted to an emergency room for pre-hospital treatment via WiMax/3.5 G networks. Performances of WiMax and 3.5 G, in terms of initialization time, data rate, and average end-to-end delay are evaluated and compared. A driver can choose the route of the shortest time among the suggested routes by Google Maps after inspecting the current traffic conditions based on real-time CCTV camera streams and traffic information. The destination address can be inputted vocally for easiness and safety in driving. A series of field test results validates the feasibility of the proposed system for application in real-life scenarios. Full article

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

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20 pages, 6983 KiB

Open AccessArticle

Evaluation on Radiometric Capability of Chinese Optical Satellite Sensors

by Aixia Yang^1,2, Bo Zhong^1,*

, Shanlong Wu¹ and Qinhuo Liu^1,2,*

¹ State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100101, China

² College of Resource and Environment, University of Chinese Academy of Sciences, Beijing 100049, China

Sensors 2017, 17(1), 204; https://doi.org/10.3390/s17010204 - 22 Jan 2017

Cited by 13 | Viewed by 5339

Abstract

The radiometric capability of on-orbit sensors should be updated on time due to changes induced by space environmental factors and instrument aging. Some sensors, such as Moderate Resolution Imaging Spectroradiometer (MODIS), have onboard calibrators, which enable real-time calibration. However, most Chinese remote sensing [...] Read more.

The radiometric capability of on-orbit sensors should be updated on time due to changes induced by space environmental factors and instrument aging. Some sensors, such as Moderate Resolution Imaging Spectroradiometer (MODIS), have onboard calibrators, which enable real-time calibration. However, most Chinese remote sensing satellite sensors lack onboard calibrators. Their radiometric calibrations have been updated once a year based on a vicarious calibration procedure, which has affected the applications of the data. Therefore, a full evaluation of the sensors’ radiometric capabilities is essential before quantitative applications can be made. In this study, a comprehensive procedure for evaluating the radiometric capability of several Chinese optical satellite sensors is proposed. In this procedure, long-term radiometric stability and radiometric accuracy are the two major indicators for radiometric evaluation. The radiometric temporal stability is analyzed by the tendency of long-term top-of-atmosphere (TOA) reflectance variation; the radiometric accuracy is determined by comparison with the TOA reflectance from MODIS after spectrally matching. Three Chinese sensors including the Charge-Coupled Device (CCD) camera onboard Huan Jing 1 satellite (HJ-1), as well as the Visible and Infrared Radiometer (VIRR) and Medium-Resolution Spectral Imager (MERSI) onboard the Feng Yun 3 satellite (FY-3) are evaluated in reflective bands based on this procedure. The results are reasonable, and thus can provide reliable reference for the sensors’ application, and as such will promote the development of Chinese satellite data. Full article

(This article belongs to the Special Issue Sensors and Smart Sensing of Agricultural Land Systems)

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11 pages, 3526 KiB

Open AccessArticle

A Low Frequency FBG Accelerometer with Symmetrical Bended Spring Plates

by Fufei Liu¹, Yutang Dai^1,*, Joseph Muna Karanja² and Minghong Yang^1,*

¹ National Engineering Laboratory for Fiber Optic Sensing Technology, Wuhan University of Technology, Luoshi Road 122, 430070 Wuhan, China

² Physics Department, Pwani University, P.O. Box 195-80108 Kilifi, Kenya

Sensors 2017, 17(1), 206; https://doi.org/10.3390/s17010206 - 22 Jan 2017

Cited by 50 | Viewed by 7454

Abstract

To meet the requirements for low-frequency vibration monitoring, a new type of FBG (fiber Bragg grating) accelerometer with a bended spring plate is proposed. Two symmetrical bended spring plates are used as elastic elements, which drive the FBG to produce axial strains equal [...] Read more.

To meet the requirements for low-frequency vibration monitoring, a new type of FBG (fiber Bragg grating) accelerometer with a bended spring plate is proposed. Two symmetrical bended spring plates are used as elastic elements, which drive the FBG to produce axial strains equal in magnitude but opposite in direction when exciting vibrations exist, leading to doubling the wavelength shift of the FBG. The mechanics model and a numerical method are presented in this paper, with which the influence of the structural parameters on the sensitivity and the eigenfrequency are discussed. The test results show that the sensitivity of the accelerometer is more than 1000 pm/g when the frequency is within the 0.7–20 Hz range. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 917 KiB

Open AccessArticle

Object Detection and Classification by Decision-Level Fusion for Intelligent Vehicle Systems

by Sang-Il Oh

and Hang-Bong Kang^*

Department of Media Engineering, Catholic University of Korea, 43-1, Yeoggok 2-dong, Wonmmi-gu, Bucheon-si, Gyeonggi-do 14662, Korea

Sensors 2017, 17(1), 207; https://doi.org/10.3390/s17010207 - 22 Jan 2017

Cited by 105 | Viewed by 12484

Abstract

To understand driving environments effectively, it is important to achieve accurate detection and classification of objects detected by sensor-based intelligent vehicle systems, which are significantly important tasks. Object detection is performed for the localization of objects, whereas object classification recognizes object classes from [...] Read more.

To understand driving environments effectively, it is important to achieve accurate detection and classification of objects detected by sensor-based intelligent vehicle systems, which are significantly important tasks. Object detection is performed for the localization of objects, whereas object classification recognizes object classes from detected object regions. For accurate object detection and classification, fusing multiple sensor information into a key component of the representation and perception processes is necessary. In this paper, we propose a new object-detection and classification method using decision-level fusion. We fuse the classification outputs from independent unary classifiers, such as 3D point clouds and image data using a convolutional neural network (CNN). The unary classifiers for the two sensors are the CNN with five layers, which use more than two pre-trained convolutional layers to consider local to global features as data representation. To represent data using convolutional layers, we apply region of interest (ROI) pooling to the outputs of each layer on the object candidate regions generated using object proposal generation to realize color flattening and semantic grouping for charge-coupled device and Light Detection And Ranging (LiDAR) sensors. We evaluate our proposed method on a KITTI benchmark dataset to detect and classify three object classes: cars, pedestrians and cyclists. The evaluation results show that the proposed method achieves better performance than the previous methods. Our proposed method extracted approximately 500 proposals on a

1226 \times 370

image, whereas the original selective search method extracted approximately

10^{6} \times n

proposals. We obtained classification performance with 77.72% mean average precision over the entirety of the classes in the moderate detection level of the KITTI benchmark dataset. Full article

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

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12 pages, 2359 KiB

Open AccessArticle

Effective Calibration of Low-Cost Soil Water Content Sensors

by Heye Reemt Bogena^*

, Johan Alexander Huisman

, Bernd Schilling, Ansgar Weuthen and Harry Vereecken

Institute of Bio- and Geosciences, Agrosphere Institute (IBG-3), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

Sensors 2017, 17(1), 208; https://doi.org/10.3390/s17010208 - 21 Jan 2017

Cited by 102 | Viewed by 15664

Abstract

Soil water content is a key variable for understanding and modelling ecohydrological processes. Low-cost electromagnetic sensors are increasingly being used to characterize the spatio-temporal dynamics of soil water content, despite the reduced accuracy of such sensors as compared to reference electromagnetic soil water [...] Read more.

Soil water content is a key variable for understanding and modelling ecohydrological processes. Low-cost electromagnetic sensors are increasingly being used to characterize the spatio-temporal dynamics of soil water content, despite the reduced accuracy of such sensors as compared to reference electromagnetic soil water content sensing methods such as time domain reflectometry. Here, we present an effective calibration method to improve the measurement accuracy of low-cost soil water content sensors taking the recently developed SMT100 sensor (Truebner GmbH, Neustadt, Germany) as an example. We calibrated the sensor output of more than 700 SMT100 sensors to permittivity using a standard procedure based on five reference media with a known apparent dielectric permittivity (1 < K_a < 34.8). Our results showed that a sensor-specific calibration improved the accuracy of the calibration compared to single “universal” calibration. The associated additional effort in calibrating each sensor individually is relaxed by a dedicated calibration setup that enables the calibration of large numbers of sensors in limited time while minimizing errors in the calibration process. Full article

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

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13 pages, 590 KiB

Open AccessArticle

Competitive Swarm Optimizer Based Gateway Deployment Algorithm in Cyber-Physical Systems

by Shuqiang Huang^1,* and Ming Tao²

¹ Department of Optoelectronic Engineering, Jinan University, Guangzhou 510632, China

² College of Computer and Network Security, Dongguan University of Technology, Dongguan 523808, China

Sensors 2017, 17(1), 209; https://doi.org/10.3390/s17010209 - 22 Jan 2017

Cited by 7 | Viewed by 6003

Abstract

Wireless sensor network topology optimization is a highly important issue, and topology control through node selection can improve the efficiency of data forwarding, while saving energy and prolonging lifetime of the network. To address the problem of connecting a wireless sensor network to [...] Read more.

Wireless sensor network topology optimization is a highly important issue, and topology control through node selection can improve the efficiency of data forwarding, while saving energy and prolonging lifetime of the network. To address the problem of connecting a wireless sensor network to the Internet in cyber-physical systems, here we propose a geometric gateway deployment based on a competitive swarm optimizer algorithm. The particle swarm optimization (PSO) algorithm has a continuous search feature in the solution space, which makes it suitable for finding the geometric center of gateway deployment; however, its search mechanism is limited to the individual optimum (pbest) and the population optimum (gbest); thus, it easily falls into local optima. In order to improve the particle search mechanism and enhance the search efficiency of the algorithm, we introduce a new competitive swarm optimizer (CSO) algorithm. The CSO search algorithm is based on an inter-particle competition mechanism and can effectively avoid trapping of the population falling into a local optimum. With the improvement of an adaptive opposition-based search and its ability to dynamically parameter adjustments, this algorithm can maintain the diversity of the entire swarm to solve geometric K-center gateway deployment problems. The simulation results show that this CSO algorithm has a good global explorative ability as well as convergence speed and can improve the network quality of service (QoS) level of cyber-physical systems by obtaining a minimum network coverage radius. We also find that the CSO algorithm is more stable, robust and effective in solving the problem of geometric gateway deployment as compared to the PSO or Kmedoids algorithms. Full article

(This article belongs to the Special Issue New Paradigms in Cyber-Physical Social Sensing)

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9 pages, 1123 KiB

Open AccessArticle

Photoacoustic Spectroscopy for the Determination of Lung Cancer Biomarkers—A Preliminary Investigation

by Yannick Saalberg^1,2,*, Henry Bruhns¹ and Marcus Wolff¹

¹ Hamburg University of Applied Sciences, Heinrich Blasius Institute for Physical Technologies, Berliner Tor 21, 20099 Hamburg, Germany

² University of the West of Scotland, High Street, PA1 2BE Paisley, UK

Sensors 2017, 17(1), 210; https://doi.org/10.3390/s17010210 - 21 Jan 2017

Cited by 25 | Viewed by 9407

Abstract

With 1.6 million deaths per year, lung cancer is one of the leading causes of death worldwide. One reason for this high number is the absence of a preventive medical examination method. Many diagnoses occur in a late cancer stage with a low [...] Read more.

With 1.6 million deaths per year, lung cancer is one of the leading causes of death worldwide. One reason for this high number is the absence of a preventive medical examination method. Many diagnoses occur in a late cancer stage with a low survival rate. An early detection could significantly decrease the mortality. In recent decades, certain substances in human breath have been linked to certain diseases. Different studies show that it is possible to distinguish between lung cancer patients and a healthy control group by analyzing the volatile organic compounds (VOCs) in their breath. We developed a sensor based on photoacoustic spectroscopy for six of the most relevant VOCs linked to lung cancer. As a radiation source, the sensor uses an optical-parametric oscillator (OPO) in a wavelength region from 3.2 µm to 3.5 µm. The limits of detection for a single substance range between 5 ppb and 142 ppb. We also measured high resolution absorption spectra of the biomarkers compared to the data currently available from the National Institute of Standards and Technology (NIST) database, which is the basis of any selective spectroscopic detection. Future lung cancer screening devices could be based on the further development of this sensor. Full article

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

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11 pages, 1944 KiB

Open AccessArticle

Evaluation of Commercial Self-Monitoring Devices for Clinical Purposes: Results from the Future Patient Trial, Phase I

by Soren Leth^1,*, John Hansen^1,2

, Olav W. Nielsen³ and Birthe Dinesen¹

¹ Laboratory of Welfare Technologies—Telehealth & Telerehabilitation, SMI, Department of Health Science and Technology, Aalborg University, Aalborg 9100, Denmark

² Medical Informatics Group, Department of Health Science and Technology, Aalborg University, Aalborg 9100, Denmark

³ Department of Cardiology, Copenhagen University Hospital Bispebjerg, Copenhagen NV 2400, Denmark

Sensors 2017, 17(1), 211; https://doi.org/10.3390/s17010211 - 22 Jan 2017

Cited by 55 | Viewed by 11102

Abstract

Commercial self-monitoring devices are becoming increasingly popular, and over the last decade, the use of self-monitoring technology has spread widely in both consumer and medical markets. The purpose of this study was to evaluate five commercially available self-monitoring devices for further testing in [...] Read more.

Commercial self-monitoring devices are becoming increasingly popular, and over the last decade, the use of self-monitoring technology has spread widely in both consumer and medical markets. The purpose of this study was to evaluate five commercially available self-monitoring devices for further testing in clinical applications. Four activity trackers and one sleep tracker were evaluated based on step count validity and heart rate validity. Methods: The study enrolled 22 healthy volunteers in a walking test. Volunteers walked a 100 m track at 2 km/h and 3.5 km/h. Steps were measured by four activity trackers and compared to gyroscope readings. Two trackers were also tested on nine subjects by comparing pulse readings to Holter monitoring. Results: The lowest average systematic error in the walking tests was −0.2%, recorded on the Garmin Vivofit 2 at 3.5 km/h; the highest error was the Fitbit Charge HR at 2 km/h with an error margin of 26.8%. Comparisons of pulse measurements from the Fitbit Charge HR revealed a margin error of −3.42% ± 7.99% compared to the electrocardiogram. The Beddit sleep tracker measured a systematic error of −3.27% ± 4.60%. Conclusion: The measured results revealed the current functionality and limitations of the five self-tracking devices, and point towards a need for future research in this area. Full article

(This article belongs to the Special Issue Sensing Technology for Healthcare System)

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10 pages, 954 KiB

Open AccessArticle

Fabrication Technology and Characteristics of a Magnetic Sensitive Transistor with nc-Si:H/c-Si Heterojunction

by Xiaofeng Zhao^*, Baozeng Li and Dianzhong Wen

School of Electronic Engineering, Heilongjiang University, Harbin 150080, China

Sensors 2017, 17(1), 212; https://doi.org/10.3390/s17010212 - 22 Jan 2017

Cited by 7 | Viewed by 5920

Abstract

This paper presents a magnetically sensitive transistor using a nc-Si:H/c-Si heterojunction as an emitter junction. By adopting micro electro-mechanical systems (MEMS) technology and chemical vapor deposition (CVD) method, the nc-Si:H/c-Si heterojunction silicon magnetically sensitive transistor (HSMST) chips were designed and fabricated on a [...] Read more.

This paper presents a magnetically sensitive transistor using a nc-Si:H/c-Si heterojunction as an emitter junction. By adopting micro electro-mechanical systems (MEMS) technology and chemical vapor deposition (CVD) method, the nc-Si:H/c-Si heterojunction silicon magnetically sensitive transistor (HSMST) chips were designed and fabricated on a p-type <100> orientation double-side polished silicon wafer with high resistivity. In addition, a collector load resistor (

R_{L}

) was integrated on the chip, and the resistor converted the collector current (

I_{C}

) to a collector output voltage (

V_{out}

). When

I_{B}

= 8.0 mA,

V_{DD}

= 10.0 V, and

R_{L}

= 4.1 kΩ, the magnetic sensitivity (

S_{V}

) at room temperature and temperature coefficient (

α_{C}

) of the collector current for HSMST were 181 mV/T and −0.11%/°C, respectively. The experimental results show that the magnetic sensitivity and temperature characteristics of the proposed transistor can be obviously improved by the use of a nc-Si:H/c-Si heterojunction as an emitter junction. Full article

(This article belongs to the Special Issue MEMS and Nano-Sensors)

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23 pages, 14910 KiB

Open AccessArticle

Vinobot and Vinoculer: Two Robotic Platforms for High-Throughput Field Phenotyping

by Ali Shafiekhani¹, Suhas Kadam², Felix B. Fritschi² and Guilherme N. DeSouza^1,*

¹ ViGIR Lab, Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO 65211, USA

² Division of Plant Sciences, University of Missouri, Columbia, MO 65211, USA

Sensors 2017, 17(1), 214; https://doi.org/10.3390/s17010214 - 23 Jan 2017

Cited by 137 | Viewed by 18366

Abstract

In this paper, a new robotic architecture for plant phenotyping is being introduced. The architecture consists of two robotic platforms: an autonomous ground vehicle (Vinobot) and a mobile observation tower (Vinoculer). The ground vehicle collects data from individual plants, while the observation tower [...] Read more.

In this paper, a new robotic architecture for plant phenotyping is being introduced. The architecture consists of two robotic platforms: an autonomous ground vehicle (Vinobot) and a mobile observation tower (Vinoculer). The ground vehicle collects data from individual plants, while the observation tower oversees an entire field, identifying specific plants for further inspection by the Vinobot. The advantage of this architecture is threefold: first, it allows the system to inspect large areas of a field at any time, during the day and night, while identifying specific regions affected by biotic and/or abiotic stresses; second, it provides high-throughput plant phenotyping in the field by either comprehensive or selective acquisition of accurate and detailed data from groups or individual plants; and third, it eliminates the need for expensive and cumbersome aerial vehicles or similarly expensive and confined field platforms. As the preliminary results from our algorithms for data collection and 3D image processing, as well as the data analysis and comparison with phenotype data collected by hand demonstrate, the proposed architecture is cost effective, reliable, versatile, and extendable. Full article

(This article belongs to the Special Issue Vision-Based Sensors in Field Robotics)

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16 pages, 23328 KiB

Open AccessArticle

Three-Dimensional Measurement for Specular Reflection Surface Based on Reflection Component Separation and Priority Region Filling Theory

by Xiaoming Sun^*, Ye Liu, Xiaoyang Yu^*, Haibin Wu and Ning Zhang

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

Sensors 2017, 17(1), 215; https://doi.org/10.3390/s17010215 - 23 Jan 2017

Cited by 31 | Viewed by 8024

Abstract

Due to the strong reflection property of materials with smooth surfaces like ceramic and metal, it will cause saturation and the highlight phenomenon in the image when taking pictures of those materials. In order to solve this problem, a new algorithm which is [...] Read more.

Due to the strong reflection property of materials with smooth surfaces like ceramic and metal, it will cause saturation and the highlight phenomenon in the image when taking pictures of those materials. In order to solve this problem, a new algorithm which is based on reflection component separation (RCS) and priority region filling theory is designed. Firstly, the specular pixels in the image are found by comparing the pixel parameters. Then, the reflection components are separated and processed. However, for ceramic, metal and other objects with strong specular highlight, RCS theory will change color information of highlight pixels due to larger specular reflection component. In this situation, priority region filling theory was used to restore the color information. Finally, we implement 3D experiments on objects with strong reflecting surfaces like ceramic plate, ceramic bottle, marble pot and yellow plate. Experimental results show that, with the proposed method, the highlight caused by the strong reflecting surface can be well suppressed. The highlight pixel number of ceramic plate, ceramic bottle, marble pot and yellow plate, is decreased by 43.8 times, 41.4 times, 33.0 times, and 10.1 times. Three-dimensional reconstruction results show that highlight areas were significantly reduced. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 18729 KiB

Open AccessArticle

An Adaptive Moving Target Imaging Method for Bistatic Forward-Looking SAR Using Keystone Transform and Optimization NLCS

by Zhongyu Li^1,2,*,†, Junjie Wu^1,†, Yulin Huang¹, Haiguang Yang¹ and Jianyu Yang¹

¹ School of Electronic Engineering, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave, West Hi-Tech Zone, Chengdu 611731, China

² Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome “La Sapienza”, Via Eudossianan, n.18, cap 00184 Roma, Italy

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 216; https://doi.org/10.3390/s17010216 - 23 Jan 2017

Cited by 6 | Viewed by 5364

Abstract

Bistatic forward-looking SAR (BFSAR) is a kind of bistatic synthetic aperture radar (SAR) system that can image forward-looking terrain in the flight direction of an aircraft. Until now, BFSAR imaging theories and methods for a stationary scene have been researched thoroughly. However, for [...] Read more.

Bistatic forward-looking SAR (BFSAR) is a kind of bistatic synthetic aperture radar (SAR) system that can image forward-looking terrain in the flight direction of an aircraft. Until now, BFSAR imaging theories and methods for a stationary scene have been researched thoroughly. However, for moving-target imaging with BFSAR, the non-cooperative movement of the moving target induces some new issues: (I) large and unknown range cell migration (RCM) (including range walk and high-order RCM); (II) the spatial-variances of the Doppler parameters (including the Doppler centroid and high-order Doppler) are not only unknown, but also nonlinear for different point-scatterers. In this paper, we put forward an adaptive moving-target imaging method for BFSAR. First, the large and unknown range walk is corrected by applying keystone transform over the whole received echo, and then, the relationships among the unknown high-order RCM, the nonlinear spatial-variances of the Doppler parameters, and the speed of the mover, are established. After that, using an optimization nonlinear chirp scaling (NLCS) technique, not only can the unknown high-order RCM be accurately corrected, but also the nonlinear spatial-variances of the Doppler parameters can be balanced. At last, a high-order polynomial filter is applied to compress the whole azimuth data of the moving target. Numerical simulations verify the effectiveness of the proposed method. Full article

(This article belongs to the Section Remote Sensors)

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12 pages, 7034 KiB

Open AccessArticle

Hierarchical NiCo₂O₄ Hollow Sphere as a Peroxidase Mimetic for Colorimetric Detection of H₂O₂ and Glucose

by Wei Huang¹, Tianye Lin¹, Yang Cao¹, Xiaoyong Lai², Juan Peng² and Jinchun Tu^1,*

¹ State Key Laboratory of Marine Resource Utilization in South China Sea, Key Laboratory of Tropical Biological Resources of Ministry of Education Hainan University, College of Material and Chemical Engineering, Haikou 570228, China

² Laboratory Cultivation Base of Natural Gas Conversion, School of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China

Sensors 2017, 17(1), 217; https://doi.org/10.3390/s17010217 - 23 Jan 2017

Cited by 43 | Viewed by 10056

Abstract

In this work, the hierarchical NiCo₂O₄ hollow sphere synthesized via a “coordinating etching and precipitating” process was demonstrated to exhibit intrinsic peroxidase-like activity. The peroxidase-like activity of NiCo₂O₄, NiO, and Co₃O₄ hollow spheres [...] Read more.

In this work, the hierarchical NiCo₂O₄ hollow sphere synthesized via a “coordinating etching and precipitating” process was demonstrated to exhibit intrinsic peroxidase-like activity. The peroxidase-like activity of NiCo₂O₄, NiO, and Co₃O₄ hollow spheres were comparatively studied by the catalytic oxidation reaction of 3,3,5,5-tetramethylbenzidine (TMB) in presence of H₂O₂, and a superior peroxidase-like activity of NiCo₂O₄ was confirmed by stronger absorbance at 652 nm. Furthermore, the proposed sensing platform showed commendable response to H₂O₂ with a linear range from 10 μM to 400 μM, and a detection limit of 0.21 μM. Cooperated with GOx, the developed novel colorimetric and visual glucose-sensing platform exhibited high selectivity, favorable reproducibility, satisfactory applicability, wide linear range (from 0.1 mM to 4.5 mM), and a low detection limit of 5.31 μM. In addition, the concentration-dependent color change would offer a better and handier way for detection of H₂O₂ and glucose by naked eye. Full article

(This article belongs to the Special Issue Colorimetric and Fluorescent Sensor)

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12 pages, 5603 KiB

Open AccessArticle

Diaphragm Based Fiber Bragg Grating Acceleration Sensor with Temperature Compensation

by Tianliang Li^*

, Yuegang Tan, Xue Han, Kai Zheng

and Zude Zhou

School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070, China

Sensors 2017, 17(1), 218; https://doi.org/10.3390/s17010218 - 23 Jan 2017

Cited by 96 | Viewed by 8632

Abstract

A novel fiber Bragg grating (FBG) sensing-based acceleration sensor has been proposed to simultaneously decouple and measure temperature and acceleration in real-time. This design applied a diaphragm structure and utilized the axial property of a tightly suspended optical fiber, enabling improvement in its [...] Read more.

A novel fiber Bragg grating (FBG) sensing-based acceleration sensor has been proposed to simultaneously decouple and measure temperature and acceleration in real-time. This design applied a diaphragm structure and utilized the axial property of a tightly suspended optical fiber, enabling improvement in its sensitivity and resonant frequency and achieve a low cross-sensitivity. The theoretical vibrational model of the sensor has been built, and its design parameters and sensing properties have been analyzed through the numerical analysis. A decoupling method has been presented with consideration of the thermal expansion of the sensor structure to realize temperature compensation. Experimental results show that the temperature sensitivity is 8.66 pm/°C within the range of 30–90 °C. The acceleration sensitivity is 20.189 pm/g with a linearity of 0.764% within the range of 5~65 m/s². The corresponding working bandwidth is 10~200 Hz and its resonant frequency is 600 Hz. This sensor possesses an excellent impact resistance for the cross direction, and the cross-axis sensitivity is below 3.31%. This implementation can avoid the FBG-pasting procedure and overcome its associated shortcomings. The performance of the proposed acceleration sensor can be easily adjusted by modifying their corresponding physical parameters to satisfy requirements from different vibration measurements. Full article

(This article belongs to the Section Physical Sensors)

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Jump to: Editorial, Research, Other

23 pages, 3175 KiB

Open AccessReview

Plasmonic Fiber Optic Refractometric Sensors: From Conventional Architectures to Recent Design Trends

by Elizaveta Klantsataya^1,*, Peipei Jia^1,2, Heike Ebendorff-Heidepriem^1,2, Tanya M. Monro^1,3 and Alexandre François^1,3

¹ Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA 5005, Australia

² ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), The University of Adelaide, Adelaide, SA 5005, Australia

³ The University of South Australia, Adelaide, SA 5001, Australia

Sensors 2017, 17(1), 12; https://doi.org/10.3390/s17010012 - 23 Dec 2016

Cited by 184 | Viewed by 16522

Abstract

Surface Plasmon Resonance (SPR) fiber sensor research has grown since the first demonstration over 20 year ago into a rich and diverse field with a wide range of optical fiber architectures, plasmonic coatings, and excitation and interrogation methods. Yet, the large diversity of [...] Read more.

Surface Plasmon Resonance (SPR) fiber sensor research has grown since the first demonstration over 20 year ago into a rich and diverse field with a wide range of optical fiber architectures, plasmonic coatings, and excitation and interrogation methods. Yet, the large diversity of SPR fiber sensor designs has made it difficult to understand the advantages of each approach. Here, we review SPR fiber sensor architectures, covering the latest developments from optical fiber geometries to plasmonic coatings. By developing a systematic approach to fiber-based SPR designs, we identify and discuss future research opportunities based on a performance comparison of the different approaches for sensing applications. Full article

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

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24 pages, 9436 KiB

Open AccessReview

Literature Review: Theory and Application of In-Line Inspection Technologies for Oil and Gas Pipeline Girth Weld Defection

by Qingshan Feng^1,2,*, Rui Li^2,3,*

, Baohua Nie⁴, Shucong Liu⁵, Lianyu Zhao² and Hong Zhang¹

¹ School of Mechanical and Transportation Engineering, China University of Petroleum, Beijing 102249, China

² PetroChina Pipeline Company, Langfang 065000, China

³ School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China

⁴ School of Materials Science and Energy Engineering, FoShan University, Foshan 528000, China

⁵ Institute of Disaster Prevention, Sanhe 065201, China

Sensors 2017, 17(1), 50; https://doi.org/10.3390/s17010050 - 28 Dec 2016

Cited by 104 | Viewed by 16651

Abstract

Girth weld cracking is one of the main failure modes in oil and gas pipelines; girth weld cracking inspection has great economic and social significance for the intrinsic safety of pipelines. This paper introduces the typical girth weld defects of oil and gas [...] Read more.

Girth weld cracking is one of the main failure modes in oil and gas pipelines; girth weld cracking inspection has great economic and social significance for the intrinsic safety of pipelines. This paper introduces the typical girth weld defects of oil and gas pipelines and the common nondestructive testing methods, and systematically generalizes the progress in the studies on technical principles, signal analysis, defect sizing method and inspection reliability, etc., of magnetic flux leakage (MFL) inspection, liquid ultrasonic inspection, electromagnetic acoustic transducer (EMAT) inspection and remote field eddy current (RFDC) inspection for oil and gas pipeline girth weld defects. Additionally, it introduces the new technologies for composite ultrasonic, laser ultrasonic, and magnetostriction inspection, and provides reference for development and application of oil and gas pipeline girth weld defect in-line inspection technology. Full article

(This article belongs to the Section Physical Sensors)

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26 pages, 5806 KiB

Open AccessReview

Nanobiosensing with Arrays and Ensembles of Nanoelectrodes

by Najmeh Karimian

, Ligia M. Moretto and Paolo Ugo^*

Department of Molecular Sciences and Nanosystems, University Ca’ Foscari of Venice, Via Torino 155–Mestre, 30172 Venice, Italy

Sensors 2017, 17(1), 65; https://doi.org/10.3390/s17010065 - 30 Dec 2016

Cited by 29 | Viewed by 8300

Abstract

Since the first reports dating back to the mid-1990s, ensembles and arrays of nanoelectrodes (NEEs and NEAs, respectively) have gained an important role as advanced electroanalytical tools thank to their unique characteristics which include, among others, dramatically improved signal/noise ratios, enhanced mass transport [...] Read more.

Since the first reports dating back to the mid-1990s, ensembles and arrays of nanoelectrodes (NEEs and NEAs, respectively) have gained an important role as advanced electroanalytical tools thank to their unique characteristics which include, among others, dramatically improved signal/noise ratios, enhanced mass transport and suitability for extreme miniaturization. From the year 2000 onward, these properties have been exploited to develop electrochemical biosensors in which the surfaces of NEEs/NEAs have been functionalized with biorecognition layers using immobilization modes able to take the maximum advantage from the special morphology and composite nature of their surface. This paper presents an updated overview of this field. It consists of two parts. In the first, we discuss nanofabrication methods and the principles of functioning of NEEs/NEAs, focusing, in particular, on those features which are important for the development of highly sensitive and miniaturized biosensors. In the second part, we review literature references dealing the bioanalytical and biosensing applications of sensors based on biofunctionalized arrays/ensembles of nanoelectrodes, focusing our attention on the most recent advances, published in the last five years. The goal of this review is both to furnish fundamental knowledge to researchers starting their activity in this field and provide critical information on recent achievements which can stimulate new ideas for future developments to experienced scientists. Full article

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

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26 pages, 7010 KiB

Open AccessReview

CMOS Electrochemical Instrumentation for Biosensor Microsystems: A Review

by Haitao Li^1,*,†, Xiaowen Liu^2,†, Lin Li³, Xiaoyi Mu⁴, Roman Genov⁵ and Andrew J. Mason³

¹ Maxim Integrated Products Inc., 160 Rio Robles, San Jose, CA 95134, USA

² Xcellcure LLC., 1 City Place Drive Suite 285, St. Louis, MO 63131, USA

³ Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, USA

⁴ Apple Inc., 1 Infinite Loop, Cupertino, CA 95014, USA

⁵ Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3G4, Canada

^† The authors have equal contributions to this paper.

Sensors 2017, 17(1), 74; https://doi.org/10.3390/s17010074 - 31 Dec 2016

Cited by 151 | Viewed by 18289

Abstract

Modern biosensors play a critical role in healthcare and have a quickly growing commercial market. Compared to traditional optical-based sensing, electrochemical biosensors are attractive due to superior performance in response time, cost, complexity and potential for miniaturization. To address the shortcomings of traditional [...] Read more.

Modern biosensors play a critical role in healthcare and have a quickly growing commercial market. Compared to traditional optical-based sensing, electrochemical biosensors are attractive due to superior performance in response time, cost, complexity and potential for miniaturization. To address the shortcomings of traditional benchtop electrochemical instruments, in recent years, many complementary metal oxide semiconductor (CMOS) instrumentation circuits have been reported for electrochemical biosensors. This paper provides a review and analysis of CMOS electrochemical instrumentation circuits. First, important concepts in electrochemical sensing are presented from an instrumentation point of view. Then, electrochemical instrumentation circuits are organized into functional classes, and reported CMOS circuits are reviewed and analyzed to illuminate design options and performance tradeoffs. Finally, recent trends and challenges toward on-CMOS sensor integration that could enable highly miniaturized electrochemical biosensor microsystems are discussed. The information in the paper can guide next generation electrochemical sensor design. Full article

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

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45 pages, 4307 KiB

Open AccessFeature PaperReview

Wearable Sensors for Remote Health Monitoring

by Sumit Majumder¹, Tapas Mondal² and M. Jamal Deen^1,*

¹ Department of Electrical and Computer Engineering, McMaster University, Hamilton, ON L8S 4L8, Canada

² Department of Pediatrics, McMaster University, Hamilton, ON L8S 4L8, Canada

Sensors 2017, 17(1), 130; https://doi.org/10.3390/s17010130 - 12 Jan 2017

Cited by 994 | Viewed by 69826

Abstract

Life expectancy in most countries has been increasing continually over the several few decades thanks to significant improvements in medicine, public health, as well as personal and environmental hygiene. However, increased life expectancy combined with falling birth rates are expected to engender a [...] Read more.

Life expectancy in most countries has been increasing continually over the several few decades thanks to significant improvements in medicine, public health, as well as personal and environmental hygiene. However, increased life expectancy combined with falling birth rates are expected to engender a large aging demographic in the near future that would impose significant burdens on the socio-economic structure of these countries. Therefore, it is essential to develop cost-effective, easy-to-use systems for the sake of elderly healthcare and well-being. Remote health monitoring, based on non-invasive and wearable sensors, actuators and modern communication and information technologies offers an efficient and cost-effective solution that allows the elderly to continue to live in their comfortable home environment instead of expensive healthcare facilities. These systems will also allow healthcare personnel to monitor important physiological signs of their patients in real time, assess health conditions and provide feedback from distant facilities. In this paper, we have presented and compared several low-cost and non-invasive health and activity monitoring systems that were reported in recent years. A survey on textile-based sensors that can potentially be used in wearable systems is also presented. Finally, compatibility of several communication technologies as well as future perspectives and research challenges in remote monitoring systems will be discussed. Full article

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

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23 pages, 411 KiB

Open AccessReview

The Clinical Benefits and Accuracy of Continuous Glucose Monitoring Systems in Critically Ill Patients—A Systematic Scoping Review

by Sigrid C. J. Van Steen^1,*, Saskia Rijkenberg², Jacqueline Limpens³, Peter H. J. Van der Voort², Jeroen Hermanides⁴ and J. Hans DeVries¹

¹ Clinical Diabetology, Academic Medical Center, P.O. Box 22660, 1100 DD Amsterdam, The Netherlands

² Department of Intensive Care Medicine, Onze Lieve Vrouwe Gasthuis, P.O. Box 95500, 1090 HM Amsterdam, The Netherlands

³ Medical Library, Academic Medical Center, P.O. Box 22660, 1100 DD Amsterdam, The Netherlands

⁴ Department of Anesthesiology, Academic Medical Center, P.O. Box 22660, 1100 DD Amsterdam, The Netherlands

Sensors 2017, 17(1), 146; https://doi.org/10.3390/s17010146 - 14 Jan 2017

Cited by 45 | Viewed by 9316

Abstract

Continuous Glucose Monitoring (CGM) systems could improve glycemic control in critically ill patients. We aimed to identify the evidence on the clinical benefits and accuracy of CGM systems in these patients. For this, we performed a systematic search in Ovid MEDLINE, from inception [...] Read more.

Continuous Glucose Monitoring (CGM) systems could improve glycemic control in critically ill patients. We aimed to identify the evidence on the clinical benefits and accuracy of CGM systems in these patients. For this, we performed a systematic search in Ovid MEDLINE, from inception to 26 July 2016. Outcomes were efficacy, accuracy, safety, workload and costs. Our search retrieved 356 articles, of which 37 were included. Randomized controlled trials on efficacy were scarce (n = 5) and show methodological limitations. CGM with automated insulin infusion improved time in target and mean glucose in one trial and two trials showed a decrease in hypoglycemic episodes and time in hypoglycemia. Thirty-two articles assessed accuracy, which was overall moderate to good, the latter mainly with intravascular devices. Accuracy in critically ill children seemed lower than in adults. Adverse events were rare. One study investigated the effect on workload and cost, and showed a significant reduction in both. In conclusion, studies on the efficacy and accuracy were heterogeneous and difficult to compare. There was no consistent clinical benefit in the small number of studies available. Overall accuracy was moderate to good with some intravascular devices. CGM systems seemed however safe, and might positively affect workload and costs. Full article

(This article belongs to the Special Issue Glucose Sensors: Revolution in Diabetes Management 2016)

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24 pages, 3362 KiB

Open AccessReview

State-of-the-Art: DTM Generation Using Airborne LIDAR Data

by Ziyue Chen^1,*

, Bingbo Gao² and Bernard Devereux³

¹ College of Global Change and Earth System Science, Beijing Normal University, 19 Xinjiekouwai Street, Beijing 100875, China

² Beijing Research Center for Information Technology in Agriculture, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China

³ Department of Geography, University of Cambridge UK, CB2 3EN Cambridge, UK

Sensors 2017, 17(1), 150; https://doi.org/10.3390/s17010150 - 14 Jan 2017

Cited by 186 | Viewed by 13108

Abstract

Digital terrain model (DTM) generation is the fundamental application of airborne Lidar data. In past decades, a large body of studies has been conducted to present and experiment a variety of DTM generation methods. Although great progress has been made, DTM generation, especially [...] Read more.

Digital terrain model (DTM) generation is the fundamental application of airborne Lidar data. In past decades, a large body of studies has been conducted to present and experiment a variety of DTM generation methods. Although great progress has been made, DTM generation, especially DTM generation in specific terrain situations, remains challenging. This research introduces the general principles of DTM generation and reviews diverse mainstream DTM generation methods. In accordance with the filtering strategy, these methods are classified into six categories: surface-based adjustment; morphology-based filtering, triangulated irregular network (TIN)-based refinement, segmentation and classification, statistical analysis and multi-scale comparison. Typical methods for each category are briefly introduced and the merits and limitations of each category are discussed accordingly. Despite different categories of filtering strategies, these DTM generation methods present similar difficulties when implemented in sharply changing terrain, areas with dense non-ground features and complicated landscapes. This paper suggests that the fusion of multi-sources and integration of different methods can be effective ways for improving the performance of DTM generation. Full article

(This article belongs to the Section Remote Sensors)

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24 pages, 6524 KiB

Open AccessReview

Optical Fibre Sensors Using Graphene-Based Materials: A Review

by Miguel Hernaez^1,*

, Carlos R. Zamarreño^2,3,*, Sonia Melendi-Espina⁴

, Liam R. Bird⁴, Andrew G. Mayes¹

and Francisco J. Arregui^2,3

¹ School of Chemistry, Faculty of Science, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK

² Department of Electrical and Electronic Engineering, Universidad Publica de Navarra, Pamplona 31006, Spain

³ Institute of Smart Cities, Universidad Publica de Navarra, Pamplona 31006, Spain

⁴ School of Mathematics, Faculty of Science, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK

Sensors 2017, 17(1), 155; https://doi.org/10.3390/s17010155 - 14 Jan 2017

Cited by 113 | Viewed by 12230

Abstract

Graphene and its derivatives have become the most explored materials since Novoselov and Geim (Nobel Prize winners for Physics in 2010) achieved its isolation in 2004. The exceptional properties of graphene have attracted the attention of the scientific community from different research fields, [...] Read more.

Graphene and its derivatives have become the most explored materials since Novoselov and Geim (Nobel Prize winners for Physics in 2010) achieved its isolation in 2004. The exceptional properties of graphene have attracted the attention of the scientific community from different research fields, generating high impact not only in scientific journals, but also in general-interest newspapers. Optical fibre sensing is one of the many fields that can benefit from the use of these new materials, combining the amazing morphological, chemical, optical and electrical features of graphene with the advantages that optical fibre offers over other sensing strategies. In this document, a review of the current state of the art for optical fibre sensors based on graphene materials is presented. Full article

(This article belongs to the Section Chemical Sensors)

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19 pages, 2605 KiB

Open AccessReview

Current and Emerging Technology for Continuous Glucose Monitoring

by Cheng Chen^1,†

, Xue-Ling Zhao^1,†, Zhan-Hong Li¹

, Zhi-Gang Zhu^1,*, Shao-Hong Qian² and Andrew J. Flewitt³

¹ School of Environmental and Materials Engineering, College of Engineering, Shanghai Polytechnic University, Shanghai 201209, China

² Department of Ophthalmology, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai 200231, China

³ Electrical Engineering Division, Department of Engineering, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0FA, UK

^† These authors contributed equally to this work.

Sensors 2017, 17(1), 182; https://doi.org/10.3390/s17010182 - 19 Jan 2017

Cited by 237 | Viewed by 54942

Abstract

Diabetes has become a leading cause of death worldwide. Although there is no cure for diabetes, blood glucose monitoring combined with appropriate medication can enhance treatment efficiency, alleviate the symptoms, as well as diminish the complications. For point-of-care purposes, continuous glucose monitoring (CGM) [...] Read more.

Diabetes has become a leading cause of death worldwide. Although there is no cure for diabetes, blood glucose monitoring combined with appropriate medication can enhance treatment efficiency, alleviate the symptoms, as well as diminish the complications. For point-of-care purposes, continuous glucose monitoring (CGM) devices are considered to be the best candidates for diabetes therapy. This review focuses on current growth areas of CGM technologies, specifically focusing on subcutaneous implantable electrochemical glucose sensors. The superiority of CGM systems is introduced firstly, and then the strategies for fabrication of minimally-invasive and non-invasive CGM biosensors are discussed, respectively. Finally, we briefly outline the current status and future perspective for CGM systems. Full article

(This article belongs to the Special Issue Glucose Sensors: Revolution in Diabetes Management 2016)

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20 pages, 3559 KiB

Open AccessReview

Imaging and Force Recognition of Single Molecular Behaviors Using Atomic Force Microscopy

by Mi Li¹, Dan Dang², Lianqing Liu^1,*, Ning Xi^1,3,* and Yuechao Wang¹

¹ State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China

² School of Medical Device, Shenyang Pharmaceutical University, Shenyang 110016, China

³ Department of Industrial and Manufacturing Systems Engineering, The University of Hong Kong, Hong Kong, China

Sensors 2017, 17(1), 200; https://doi.org/10.3390/s17010200 - 22 Jan 2017

Cited by 33 | Viewed by 11076

Abstract

The advent of atomic force microscopy (AFM) has provided a powerful tool for investigating the behaviors of single native biological molecules under physiological conditions. AFM can not only image the conformational changes of single biological molecules at work with sub-nanometer resolution, but also [...] Read more.

The advent of atomic force microscopy (AFM) has provided a powerful tool for investigating the behaviors of single native biological molecules under physiological conditions. AFM can not only image the conformational changes of single biological molecules at work with sub-nanometer resolution, but also sense the specific interactions of individual molecular pair with piconewton force sensitivity. In the past decade, the performance of AFM has been greatly improved, which makes it widely used in biology to address diverse biomedical issues. Characterizing the behaviors of single molecules by AFM provides considerable novel insights into the underlying mechanisms guiding life activities, contributing much to cell and molecular biology. In this article, we review the recent developments of AFM studies in single-molecule assay. The related techniques involved in AFM single-molecule assay were firstly presented, and then the progress in several aspects (including molecular imaging, molecular mechanics, molecular recognition, and molecular activities on cell surface) was summarized. The challenges and future directions were also discussed. Full article

(This article belongs to the Special Issue Single-Molecule Sensing)

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16 pages, 2601 KiB

Open AccessReview

Gas Sensors Based on Polymer Field-Effect Transistors

by Aifeng Lv¹, Yong Pan¹ and Lifeng Chi^1,2,*

¹ Physikalisches Institut and Center for Nanotechnology (CeNTech), Universität Münster, Wilhelm-Klemm-Str. 10, Münster 48149, Germany

² Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Functional Nano and Soft Materials Laboratory (FUNSOM), Soochow University, Renai Rd. 199, Suzhou 215123, China

Sensors 2017, 17(1), 213; https://doi.org/10.3390/s17010213 - 22 Jan 2017

Cited by 84 | Viewed by 12497

Abstract

This review focuses on polymer field-effect transistor (PFET) based gas sensor with polymer as the sensing layer, which interacts with gas analyte and thus induces the change of source-drain current (ΔI_SD). Dependent on the sensing layer which can be semiconducting [...] Read more.

This review focuses on polymer field-effect transistor (PFET) based gas sensor with polymer as the sensing layer, which interacts with gas analyte and thus induces the change of source-drain current (ΔI_SD). Dependent on the sensing layer which can be semiconducting polymer, dielectric layer or conducting polymer gate, the PFET sensors can be subdivided into three types. For each type of sensor, we present the molecular structure of sensing polymer, the gas analyte and the sensing performance. Most importantly, we summarize various analyte–polymer interactions, which help to understand the sensing mechanism in the PFET sensors and can provide possible approaches for the sensor fabrication in the future. Full article

(This article belongs to the Special Issue Gas Nanosensors)

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1 pages, 137 KiB

Open AccessCorrection

Correction: Lim, S., et al. Millimeter-Wave Chemical Sensor Using Substrate-Integrated-Waveguide Cavity. Sensors 2016, 16, 1829

by Muhammad Usman Memon

and Sungjoon Lim^*

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

Sensors 2017, 17(1), 29; https://doi.org/10.3390/s17010029 - 24 Dec 2016

Cited by 4 | Viewed by 3253

Abstract

n/a Full article

(This article belongs to the Special Issue Non-Contact Sensing)

13 pages, 13966 KiB

Open AccessTechnical Note

Low Cost and Flexible UAV Deployment of Sensors

by Lars Yndal Sørensen¹

, Lars Toft Jacobsen² and John Paulin Hansen^1,*

¹ Management Engineering, Technical University of Denmark, Diplomvej, Building 372, 2800 Kgs. Lyngby, Denmark

² IT University of Copenhagen, Rued Langgaards Vej 7 2300 Copenhagen S, Denmark

Sensors 2017, 17(1), 154; https://doi.org/10.3390/s17010154 - 14 Jan 2017

Cited by 50 | Viewed by 11464

Abstract

This paper presents a platform for airborne sensor applications using low-cost, open-source components carried by an easy-to-fly unmanned aircraft vehicle (UAV). The system, available in open-source , is designed for researchers, students and makers for a broad range of exploration and data-collection needs. [...] Read more.

This paper presents a platform for airborne sensor applications using low-cost, open-source components carried by an easy-to-fly unmanned aircraft vehicle (UAV). The system, available in open-source , is designed for researchers, students and makers for a broad range of exploration and data-collection needs. The main contribution is the extensible architecture for modularized airborne sensor deployment and real-time data visualisation. Our open-source Android application provides data collection, flight path definition and map tools. Total cost of the system is below 800 dollars. The flexibility of the system is illustrated by mapping the location of Bluetooth beacons (iBeacons) on a ground field and by measuring water temperature in a lake. Full article

(This article belongs to the Special Issue UAV-Based Remote Sensing)

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12 pages, 3839 KiB

Open AccessTechnical Note

Optical Tip Clearance Measurements as a Tool for Rotating Disk Characterization

by Iker García^1,*, Joseba Zubia¹

, Josu Beloki^2,3, Jon Arrue¹

, Gaizka Durana¹ and Gotzon Aldabaldetreku¹

¹ Department of Communications Engineering, E.T.S.I. of Bilbao, University of the Basque Country UPV/EHU, Alda. Urquijo s/n Bilbao 48013, Spain

² CTA, Aeronautical Technologies Center, Bizkaia Technological Park, Zamudio 48170, Spain

³ Department of Nuclear Engineering and Fluid Mechanics, E.T.S.I. of Bilbao, University of the Basque Country (UPV/EHU), Bilbao 48013, Spain

Sensors 2017, 17(1), 165; https://doi.org/10.3390/s17010165 - 15 Jan 2017

Cited by 11 | Viewed by 5093

Abstract

An experimental investigation on the vibrational behavior of a rotating disk by means of three optical fiber sensors is presented. The disk, which is a scale model of the real disk of an aircraft engine, was assembled in a wind tunnel in order [...] Read more.

An experimental investigation on the vibrational behavior of a rotating disk by means of three optical fiber sensors is presented. The disk, which is a scale model of the real disk of an aircraft engine, was assembled in a wind tunnel in order to simulate real operation conditions. The pressure difference between the upstream and downstream sides of the disk causes an airflow that might force the disk to vibrate. To characterize this vibration, a set of parameters was determined by measuring the tip clearance of the disk: the amplitude, the frequency and the number of nodal diameters in the disk. All this information allowed the design of an upgraded prototype of the disk, whose performance was also characterized by the same method. An optical system was employed for the measurements, in combination with a strain gauge mounted on the disk surface, which served to confirm the results obtained. The data of the strain gauge coincided closely with those provided by the optical fiber sensors, thus demonstrating the suitability of this innovative technique to evaluate the vibrational behavior of rotating disks. Full article

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

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14 pages, 1952 KiB

Open AccessTechnical Note

Comparison of Orbit-Based and Time-Offset-Based Geometric Correction Models for SAR Satellite Imagery Based on Error Simulation

by Seunghwan Hong

, Yoonjo Choi, Ilsuk Park and Hong-Gyoo Sohn^*

School of Civil and Environmental Engineering, Yonsei University, Seodaemun-gu, Seoul 03722, Korea

Sensors 2017, 17(1), 170; https://doi.org/10.3390/s17010170 - 17 Jan 2017

Cited by 10 | Viewed by 5520

Abstract

Geometric correction of SAR satellite imagery is the process to adjust the model parameters that define the relationship between ground and image coordinates. To achieve sub-pixel geolocation accuracy, the adoption of the appropriate geometric correction model and parameters is important. Until now, various [...] Read more.

Geometric correction of SAR satellite imagery is the process to adjust the model parameters that define the relationship between ground and image coordinates. To achieve sub-pixel geolocation accuracy, the adoption of the appropriate geometric correction model and parameters is important. Until now, various geometric correction models have been developed and applied. However, it is still difficult for general users to adopt a suitable geometric correction models having sufficient precision. In this regard, this paper evaluated the orbit-based and time-offset-based models with an error simulation. To evaluate the geometric correction models, Radarsat-1 images that have large errors in satellite orbit information and TerraSAR-X images that have a reportedly high accuracy in satellite orbit and sensor information were utilized. For Radarsat-1 imagery, the geometric correction model based on the satellite position parameters has a better performance than the model based on time-offset parameters. In the case of the TerraSAR-X imagery, two geometric correction models had similar performance and could ensure sub-pixel geolocation accuracy. Full article

(This article belongs to the Special Issue Synthetic Aperture Radars: Models, Algorithms, Techniques and Tools for Data Exploitation)

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3 pages, 533 KiB

Open AccessCorrection

Correction: Liu, B., et al. Quantitative Evaluation of Pulsed Thermography, Lock-In Thermography and Vibrothermography on Foreign Object Defect (FOD) in CFRP. Sensors 2016, 16, doi:10.3390/s16050743

by Bin Liu^1,†, Hai Zhang^2,*,†

, Henrique Fernandes^2,3

and Xavier Maldague²

¹ School of Information Science and Engineering, Shenyang University of Technology, 111 Shenliao West Road, Shenyang 110870, China

² Department of Electrical and Computer Engineering, Computer Vision and Systems Laboratory, Laval University, 1065 av. de la Médecine, QC G1V 0A6, Canada

³ Department of Mechanical Engineering, Federal University of Uberlandia, 2121 Av. Joao Naves de Avila, Uberlandia 38400-902, Brazil

^† These authors contributed equally to this work and should be considered as co-first authors.

Sensors 2017, 17(1), 195; https://doi.org/10.3390/s17010195 - 20 Jan 2017

Viewed by 5631

Abstract

n/a Full article

(This article belongs to the Special Issue Infrared and THz Sensing and Imaging)

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