Sensors

Research

12 pages, 4953 KiB

Open AccessArticle

Single-Shot Detection of Neurotransmitters in Whole-Blood Samples by Means of the Heat-Transfer Method in Combination with Synthetic Receptors

by Thijs Vandenryt^1,†, Bart Van Grinsven^1,2,†

, Kasper Eersels^1,2

, Peter Cornelis^1,3

, Safira Kholwadia⁴, Thomas J. Cleij²

, Ronald Thoelen^1,*

, Ward De Ceuninck^1,5, Marloes Peeters^1,4

and Patrick Wagner^1,3

¹ Institute for Materials Research, Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek, Belgium

² Maastricht Science Programme, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands

³ Department of Physics and Astronomy, Soft-Matter Physics and Biophysics Section, KULeuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium

⁴ Division of Chemistry and Environmental Science, School of Science and the Environment, Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK

⁵ IMOMEC Division, IMEC vzw, Wetenschapspark 1, B3590 Diepenbeek, Belgium

^† Authors share first authorship.

Sensors 2017, 17(12), 2701; https://doi.org/10.3390/s17122701 - 23 Nov 2017

Cited by 19 | Viewed by 5859

Abstract

Serotonin is an important neurotransmitter that plays a major role in the pathogenesis of a variety of conditions, including psychiatric disorders. The detection of serotonin typically relies on high-performance liquid chromatography (HPLC), an expensive technique that requires sophisticated equipment and trained personnel, and [...] Read more.

Serotonin is an important neurotransmitter that plays a major role in the pathogenesis of a variety of conditions, including psychiatric disorders. The detection of serotonin typically relies on high-performance liquid chromatography (HPLC), an expensive technique that requires sophisticated equipment and trained personnel, and is not suitable for point-of-care applications. In this contribution, we introduce a novel sensor platform that can measure spiked neurotransmitter concentrations in whole blood samples in a fast and low-cost manner by combining synthetic receptors with a thermal readout technique—the heat-transfer method. In addition, the design of a miniaturized version of the sensing platform is presented that aims to bridge the gap between measurements in a laboratory setting and point-of-care measurements. This fully automated and integrated, user-friendly design features a capillary pumping unit that is compatible with point-of-care sampling techniques such as a blood lancet device (sample volume—between 50 µL and 300 µL). Sample pre-treatment is limited to the addition of an anti-coagulant. With this fully integrated setup, it is possible to successfully discriminate serotonin from a competitor neurotransmitter (histamine) in whole blood samples. This is the first demonstration of a point-of-care ready device based on synthetic receptors for the screening of neurotransmitters in complex matrices, illustrating the sensor’s potential application in clinical research and diagnosis of e.g., early stage depression. Full article

(This article belongs to the Special Issue Polymer-Based Sensors for Bioanalytes)

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13 pages, 3786 KiB

Open AccessArticle

Verification of Non-Invasive Blood Glucose Measurement Method Based on Pulse Wave Signal Detected by FBG Sensor System

by Shintaro Kurasawa¹, Shouhei Koyama^2,*

, Hiroaki Ishizawa³, Keisaku Fujimoto⁴ and Shun Chino¹

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

² Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan

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

⁴ Department of Clinical Laboratory Sciences, School of Health Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan

Sensors 2017, 17(12), 2702; https://doi.org/10.3390/s17122702 - 23 Nov 2017

Cited by 31 | Viewed by 9155

Abstract

This paper describes and verifies a non-invasive blood glucose measurement method using a fiber Bragg grating (FBG) sensor system. The FBG sensor is installed on the radial artery, and the strain (pulse wave) that is propagated from the heartbeat is measured. The measured [...] Read more.

This paper describes and verifies a non-invasive blood glucose measurement method using a fiber Bragg grating (FBG) sensor system. The FBG sensor is installed on the radial artery, and the strain (pulse wave) that is propagated from the heartbeat is measured. The measured pulse wave signal was used as a collection of feature vectors for multivariate analysis aiming to determine the blood glucose level. The time axis of the pulse wave signal was normalized by two signal processing methods: the shortest-time-cut process and 1-s-normalization process. The measurement accuracy of the calculated blood glucose level was compared with the accuracy of these signal processing methods. It was impossible to calculate a blood glucose level exceeding 200 mg/dL in the calibration curve that was constructed by the shortest-time-cut process. In the 1-s-normalization process, the measurement accuracy of the blood glucose level was improved, and a blood glucose level exceeding 200 mg/dL could be calculated. By verifying the loading vector of each calibration curve to calculate the blood glucose level with a high measurement accuracy, we found the gradient of the peak of the pulse wave at the acceleration plethysmogram greatly affected. Full article

(This article belongs to the Special Issue Fiber Bragg Grating Based Sensors)

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19 pages, 13071 KiB

Open AccessArticle

Designing and Testing a UAV Mapping System for Agricultural Field Surveying

by Martin Peter Christiansen^1,*

, Morten Stigaard Laursen¹

, Rasmus Nyholm Jørgensen¹

, Søren Skovsen¹ and René Gislum²

¹ Department of Engineering, Aarhus University, Finlandsgade 22, 8200 Aarhus N, Denmark

² Department of Agroecology, Aarhus University, Forsøgsvej 1, 4200 Slagelse, Denmark

Sensors 2017, 17(12), 2703; https://doi.org/10.3390/s17122703 - 23 Nov 2017

Cited by 150 | Viewed by 19047

Abstract

A Light Detection and Ranging (LiDAR) sensor mounted on an Unmanned Aerial Vehicle (UAV) can map the overflown environment in point clouds. Mapped canopy heights allow for the estimation of crop biomass in agriculture. The work presented in this paper contributes to sensory [...] Read more.

A Light Detection and Ranging (LiDAR) sensor mounted on an Unmanned Aerial Vehicle (UAV) can map the overflown environment in point clouds. Mapped canopy heights allow for the estimation of crop biomass in agriculture. The work presented in this paper contributes to sensory UAV setup design for mapping and textual analysis of agricultural fields. LiDAR data are combined with data from Global Navigation Satellite System (GNSS) and Inertial Measurement Unit (IMU) sensors to conduct environment mapping for point clouds. The proposed method facilitates LiDAR recordings in an experimental winter wheat field. Crop height estimates ranging from 0.35–0.58 m are correlated to the applied nitrogen treatments of 0–300

kg \frac{N}{ha}

. The LiDAR point clouds are recorded, mapped, and analysed using the functionalities of the Robot Operating System (ROS) and the Point Cloud Library (PCL). Crop volume estimation is based on a voxel grid with a spatial resolution of 0.04 × 0.04 × 0.001 m. Two different flight patterns are evaluated at an altitude of 6 m to determine the impacts of the mapped LiDAR measurements on crop volume estimations. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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21 pages, 13577 KiB

Open AccessArticle

Statistical Analysis of the Random Telegraph Noise in a 1.1 μm Pixel, 8.3 MP CMOS Image Sensor Using On-Chip Time Constant Extraction Method

by Calvin Yi-Ping Chao^*

, Honyih Tu, Thomas Meng-Hsiu Wu, Kuo-Yu Chou, Shang-Fu Yeh, Chin Yin and Chih-Lin Lee

Taiwan Semiconductor Manufacturing Company, Hsinchu Science Park, Hsinchu 300, Taiwan

Sensors 2017, 17(12), 2704; https://doi.org/10.3390/s17122704 - 23 Nov 2017

Cited by 16 | Viewed by 9804

Abstract

A study of the random telegraph noise (RTN) of a 1.1 μm pitch, 8.3 Mpixel CMOS image sensor (CIS) fabricated in a 45 nm backside-illumination (BSI) technology is presented in this paper. A noise decomposition scheme is used to pinpoint the noise source. [...] Read more.

A study of the random telegraph noise (RTN) of a 1.1 μm pitch, 8.3 Mpixel CMOS image sensor (CIS) fabricated in a 45 nm backside-illumination (BSI) technology is presented in this paper. A noise decomposition scheme is used to pinpoint the noise source. The long tail of the random noise (RN) distribution is directly linked to the RTN from the pixel source follower (SF). The full 8.3 Mpixels are classified into four categories according to the observed RTN histogram peaks. A theoretical formula describing the RTN as a function of the time difference between the two phases of the correlated double sampling (CDS) is derived and validated by measured data. An on-chip time constant extraction method is developed and applied to the RTN analysis. The effects of readout circuit bandwidth on the settling ratios of the RTN histograms are investigated and successfully accounted for in a simulation using a RTN behavior model. Full article

(This article belongs to the Special Issue Special Issue on the 2017 International Image Sensor Workshop (IISW))

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13 pages, 2504 KiB

Open AccessArticle

Experimental Investigation on the Detection of Multiple Surface Cracks Using Vibrothermography with a Low-Power Piezoceramic Actuator

by Changhang Xu^1,*, Jing Xie¹, Wuyang Zhang¹, Qingzhao Kong^2,*

, Guoming Chen¹ and Gangbing Song²

¹ College of Mechanical and Electronic Engineering, China University of Petroleum, Qingdao 266580, China

² Department of Mechanical Engineering, University of Houston, Houston, TX 77004, USA

Sensors 2017, 17(12), 2705; https://doi.org/10.3390/s17122705 - 23 Nov 2017

Cited by 29 | Viewed by 5010

Abstract

Vibrothermography often employs a high-power actuator to generate heat on a specimen to reveal damage, however, the high-power actuator brings inconvenience to the application and possibly introduces additional damage to the inspected objects. This study uses a low-power piezoceramic transducer as the actuator [...] Read more.

Vibrothermography often employs a high-power actuator to generate heat on a specimen to reveal damage, however, the high-power actuator brings inconvenience to the application and possibly introduces additional damage to the inspected objects. This study uses a low-power piezoceramic transducer as the actuator of vibrothermography and explores its ability to detect multiple surface cracks in a metal part. Experiments were conducted on a thin aluminum beam with three cracks in different orientations. Detailed analyses of both thermograms and temperature data are presented to validate the proposed vibrothermography method. To further investigate the performance of the proposed vibrothermography method, we experimentally studied the effects of several critical factors, including the amplitude of excitation signal, specimen constraints, relative position between the transducer and cracks (the transducer is mounted on the same or the opposite side with the cracks). The results demonstrate that all cracks can be detected conveniently and simultaneously by using the proposed low-power vibrothermography. We also found that the magnitude of excitation signal and the specimen constraints have a great influence on detection results. Combined with effective data processing methods, such as Fourier transformation employed in this study, the proposed method provides a promising potential to detect multiple cracks on a metal surface in a safe and effective manner. Full article

(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)

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19 pages, 8690 KiB

Open AccessArticle

FTUC: A Flooding Tree Uneven Clustering Protocol for a Wireless Sensor Network

by Wei He^1,2,*

, Sebastien Pillement²

and Du Xu¹

¹ School of Information Engineering, Guang Dong University of Technology, Guangzhou 510000, China

² Polytech-IETR, University of Nantes, rue Christian Pauc, 44300 Nantes, France

Sensors 2017, 17(12), 2706; https://doi.org/10.3390/s17122706 - 23 Nov 2017

Cited by 2 | Viewed by 4263

Abstract

Clustering is an efficient approach in a wireless sensor network (WSN) to reduce the energy consumption of nodes and to extend the lifetime of the network. Unfortunately, this approach requires that all cluster heads (CHs) transmit their data to the base station (BS), [...] Read more.

Clustering is an efficient approach in a wireless sensor network (WSN) to reduce the energy consumption of nodes and to extend the lifetime of the network. Unfortunately, this approach requires that all cluster heads (CHs) transmit their data to the base station (BS), which gives rise to the long distance communications problem, and in multi-hop routing, the CHs near the BS have to forward data from other nodes that lead those CHs to die prematurely, creating the hot zones problem. Unequal clustering has been proposed to solve these problems. Most of the current algorithms elect CH only by considering their competition radius, leading to unevenly distributed cluster heads. Furthermore, global distances values are needed when calculating the competition radius, which is a tedious task in large networks. To face these problems, we propose a flooding tree uneven clustering protocol (FTUC) suited for large networks. Based on the construction of a tree type sub-network to calculate the minimum and maximum distances values of the network, we then apply the unequal cluster theory. We also introduce referenced position circles to evenly elect cluster heads. Therefore, cluster heads are elected depending on the node’s residual energy and their distance to a referenced circle. FTUC builds the best inter-cluster communications route by evaluating a cluster head cost function to find the best next hop to the BS. The simulation results show that the FTUC algorithm decreases the energy consumption of the nodes and balances the global energy consumption effectively, thus extending the lifetime of the network. Full article

(This article belongs to the Section Sensor Networks)

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12 pages, 5574 KiB

Open AccessArticle

Wearable Stretch Sensors for Motion Measurement of the Wrist Joint Based on Dielectric Elastomers

by Bo Huang^1,†, Mingyu Li^1,†, Tao Mei¹, David McCoul², Shihao Qin¹, Zhanfeng Zhao³ and Jianwen Zhao^1,*

¹ Department of Mechanical Engineering, Harbin Institute of Technology, Weihai 264209, China

² Department of Materials Science and Engineering, UCLA, Los Angeles, CA 90095, USA

³ Department of Electrical Engineering, Harbin Institute of Technology, Weihai 264209, China

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2708; https://doi.org/10.3390/s17122708 - 23 Nov 2017

Cited by 87 | Viewed by 15216

Abstract

Motion capture of the human body potentially holds great significance for exoskeleton robots, human-computer interaction, sports analysis, rehabilitation research, and many other areas. Dielectric elastomer sensors (DESs) are excellent candidates for wearable human motion capture systems because of their intrinsic characteristics of softness, [...] Read more.

Motion capture of the human body potentially holds great significance for exoskeleton robots, human-computer interaction, sports analysis, rehabilitation research, and many other areas. Dielectric elastomer sensors (DESs) are excellent candidates for wearable human motion capture systems because of their intrinsic characteristics of softness, light weight, and compliance. In this paper, DESs were applied to measure all component motions of the wrist joints. Five sensors were mounted to different positions on the wrist, and each one is for one component motion. To find the best position to mount the sensors, the distribution of the muscles is analyzed. Even so, the component motions and the deformation of the sensors are coupled; therefore, a decoupling method was developed. By the decoupling algorithm, all component motions can be measured with a precision of 5°, which meets the requirements of general motion capture systems. Full article

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

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21 pages, 3005 KiB

Open AccessArticle

A Polar Initial Alignment Algorithm for Unmanned Underwater Vehicles

by Zheping Yan, Lu Wang^*, Tongda Wang, Honghan Zhang, Xun Zhang and Xiangling Liu

College of Automation, Harbin Engineering University, Harbin 150001, China

Sensors 2017, 17(12), 2709; https://doi.org/10.3390/s17122709 - 23 Nov 2017

Cited by 10 | Viewed by 4122

Abstract

Due to its highly autonomy, the strapdown inertial navigation system (SINS) is widely used in unmanned underwater vehicles (UUV) navigation. Initial alignment is crucial because the initial alignment results will be used as the initial SINS value, which might affect the subsequent SINS [...] Read more.

Due to its highly autonomy, the strapdown inertial navigation system (SINS) is widely used in unmanned underwater vehicles (UUV) navigation. Initial alignment is crucial because the initial alignment results will be used as the initial SINS value, which might affect the subsequent SINS results. Due to the rapid convergence of Earth meridians, there is a calculation overflow in conventional initial alignment algorithms, making conventional initial algorithms are invalid for polar UUV navigation. To overcome these problems, a polar initial alignment algorithm for UUV is proposed in this paper, which consists of coarse and fine alignment algorithms. Based on the principle of the conical slow drift of gravity, the coarse alignment algorithm is derived under the grid frame. By choosing the velocity and attitude as the measurement, the fine alignment with the Kalman filter (KF) is derived under the grid frame. Simulation and experiment are realized among polar, conventional and transversal initial alignment algorithms for polar UUV navigation. Results demonstrate that the proposed polar initial alignment algorithm can complete the initial alignment of UUV in the polar region rapidly and accurately. Full article

(This article belongs to the Special Issue Sensors, Wireless Connectivity and Systems for Autonomous Vehicles and Smart Mobility)

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24 pages, 7102 KiB

Open AccessArticle

Turning and Radius Deviation Correction for a Hexapod Walking Robot Based on an Ant-Inspired Sensory Strategy

by Yaguang Zhu^1,2,*

, Tong Guo¹, Qiong Liu¹, Qianwei Zhu¹, Bo Jin² and Xiangmo Zhao³

¹ Key Laboratory of Road Construction Technology and Equipment of MOE, Chang’an University, Xi’an 710064, China

² State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310028, China

³ School of information Engineering, Chang’an University, Xi’an 710064, China

Sensors 2017, 17(12), 2710; https://doi.org/10.3390/s17122710 - 23 Nov 2017

Cited by 10 | Viewed by 6376

Abstract

In order to find a common approach to plan the turning of a bio-inspired hexapod robot, a locomotion strategy for turning and deviation correction of a hexapod walking robot based on the biological behavior and sensory strategy of ants. A series of experiments [...] Read more.

In order to find a common approach to plan the turning of a bio-inspired hexapod robot, a locomotion strategy for turning and deviation correction of a hexapod walking robot based on the biological behavior and sensory strategy of ants. A series of experiments using ants were carried out where the gait and the movement form of ants was studied. Taking the results of the ant experiments as inspiration by imitating the behavior of ants during turning, an extended turning algorithm based on arbitrary gait was proposed. Furthermore, after the observation of the radius adjustment of ants during turning, a radius correction algorithm based on the arbitrary gait of the hexapod robot was raised. The radius correction surface function was generated by fitting the correction data, which made it possible for the robot to move in an outdoor environment without the positioning system and environment model. The proposed algorithm was verified on the hexapod robot experimental platform. The turning and radius correction experiment of the robot with several gaits were carried out. The results indicated that the robot could follow the ideal radius and maintain stability, and the proposed ant-inspired turning strategy could easily make free turns with an arbitrary gait. Full article

(This article belongs to the Special Issue Smart Sensors for Mechatronic and Robotic Systems)

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20 pages, 5413 KiB

Open AccessArticle

Off-Nadir Hyperspectral Sensing for Estimation of Vertical Profile of Leaf Chlorophyll Content within Wheat Canopies

by Weiping Kong^1,2

, Wenjiang Huang^1,3,*

, Xianfeng Zhou¹, Huichun Ye¹, Yingying Dong¹ and Raffaele Casa⁴

¹ Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China

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

³ State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China

⁴ Department of Agricultural and Forestry scieNcEs (DAFNE), Università degli Studi della Tuscia, Via San Camillo de Lellis, 01100 Viterbo, Italy

Sensors 2017, 17(12), 2711; https://doi.org/10.3390/s17122711 - 23 Nov 2017

Cited by 27 | Viewed by 5347

Abstract

Monitoring the vertical profile of leaf chlorophyll (Chl) content within winter wheat canopies is of significant importance for revealing the real nutritional status of the crop. Information on the vertical profile of Chl content is not accessible to nadir-viewing remote or proximal sensing. [...] Read more.

Monitoring the vertical profile of leaf chlorophyll (Chl) content within winter wheat canopies is of significant importance for revealing the real nutritional status of the crop. Information on the vertical profile of Chl content is not accessible to nadir-viewing remote or proximal sensing. Off-nadir or multi-angle sensing would provide effective means to detect leaf Chl content in different vertical layers. However, adequate information on the selection of sensitive spectral bands and spectral index formulas for vertical leaf Chl content estimation is not yet available. In this study, all possible two-band and three-band combinations over spectral bands in normalized difference vegetation index (NDVI)-, simple ratio (SR)- and chlorophyll index (CI)-like types of indices at different viewing angles were calculated and assessed for their capability of estimating leaf Chl for three vertical layers of wheat canopies. The vertical profiles of Chl showed top-down declining trends and the patterns of band combinations sensitive to leaf Chl content varied among different vertical layers. Results indicated that the combinations of green band (520 nm) with NIR bands were efficient in estimating upper leaf Chl content, whereas the red edge (695 nm) paired with NIR bands were dominant in quantifying leaf Chl in the lower layers. Correlations between published spectral indices and all NDVI-, SR- and CI-like types of indices and vertical distribution of Chl content showed that reflectance measured from 50°, 30° and 20° backscattering viewing angles were the most promising to obtain information on leaf Chl in the upper-, middle-, and bottom-layer, respectively. Three types of optimized spectral indices improved the accuracy for vertical leaf Chl content estimation. The optimized three-band CI-like index performed the best in the estimation of vertical distribution of leaf Chl content, with R² of 0.84–0.69, and RMSE of 5.37–5.56 µg/cm² from the top to the bottom layers, while the optimized SR-like index was recommended for the bottom Chl estimation due to its simple and universal form. We suggest that it is necessary to take into account the penetration characteristic of the light inside the canopy for different Chl absorption regions of the spectrum and the formula used to derive spectral index when estimating the vertical profile of leaf Chl content using off-nadir hyperspectral data. Full article

(This article belongs to the Section Remote Sensors)

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15 pages, 1765 KiB

Open AccessArticle

Early Detection of the Initiation of Sit-to-Stand Posture Transitions Using Orthosis-Mounted Sensors

by Abul Doulah¹

, Xiangrong Shen² and Edward Sazonov^1,*

¹ Department of Electrical and Computer Engineering, The University of Alabama, Tuscaloosa, AL 35487, USA

² Department of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487, USA

Sensors 2017, 17(12), 2712; https://doi.org/10.3390/s17122712 - 23 Nov 2017

Cited by 10 | Viewed by 4678

Abstract

Assistance during sit-to-stand (SiSt) transitions for frail elderly may be provided by powered orthotic devices. The control of the powered orthosis may be performed by the means of electromyography (EMG), which requires direct contact of measurement electrodes to the skin. The purpose of [...] Read more.

Assistance during sit-to-stand (SiSt) transitions for frail elderly may be provided by powered orthotic devices. The control of the powered orthosis may be performed by the means of electromyography (EMG), which requires direct contact of measurement electrodes to the skin. The purpose of this study was to determine if a non-EMG-based method that uses inertial sensors placed at different positions on the orthosis, and a lightweight pattern recognition algorithm may accurately identify SiSt transitions without false positives. A novel method is proposed to eliminate false positives based on a two-stage design: stage one detects the sitting posture; stage two recognizes the initiation of a SiSt transition from a sitting position. The method was validated using data from 10 participants who performed 34 different activities and posture transitions. Features were obtained from the sensor signals and then combined into lagged epochs. A reduced number of features was selected using a minimum-redundancy-maximum-relevance (mRMR) algorithm and forward feature selection. To obtain a recognition model with low computational complexity, we compared the use of an extreme learning machine (ELM) and multilayer perceptron (MLP) for both stages of the recognition algorithm. Both classifiers were able to accurately identify all posture transitions with no false positives. The average detection time was 0.19 ± 0.33 s for ELM and 0.13 ± 0.32 s for MLP. The MLP classifier exhibited less time complexity in the recognition phase compared to ELM. However, the ELM classifier presented lower computational demands in the training phase. Results demonstrated that the proposed algorithm could potentially be adopted to control a powered orthosis. Full article

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

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16 pages, 10491 KiB

Open AccessArticle

A Microwave Microfluidic Sensor Based on a Dual-Mode Resonator for Dual-Sensing Applications

by Nikolina Jankovic and Vasa Radonic^*

BioSense Institute—Research Institute for Information Technologies in Biosystems, Novi Sad 21000, Serbia

Sensors 2017, 17(12), 2713; https://doi.org/10.3390/s17122713 - 24 Nov 2017

Cited by 52 | Viewed by 6875

Abstract

In this paper, we propose a novel microwave microfluidic sensor with dual-sensing capability. The sensor is based on a dual-mode resonator that consists of a folded microstrip line loaded with interdigital lines and a stub at the plane of symmetry. Due to the [...] Read more.

In this paper, we propose a novel microwave microfluidic sensor with dual-sensing capability. The sensor is based on a dual-mode resonator that consists of a folded microstrip line loaded with interdigital lines and a stub at the plane of symmetry. Due to the specific configuration, the resonator exhibits two entirely independent resonant modes, which allows simultaneous sensing of two fluids using a resonance shift method. The sensor is designed in a multilayer configuration with the proposed resonator and two separated microfluidic channels—one intertwined with the interdigital lines and the other positioned below the stub. The circuit has been fabricated using low-temperature co-fired ceramics technology and its performance was verified through the measurement of its responses for different fluids in the microfluidic channels. The results confirm the dual-sensing capability with zero mutual influence as well as good overall performance. Besides an excellent potential for dual-sensing applications, the proposed sensor is a good candidate for application in mixing fluids and cell counting. Full article

(This article belongs to the Special Issue Microfluidic Sensors)

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17 pages, 5387 KiB

Open AccessArticle

Monitoring the Wobbe Index of Natural Gas Using Fiber-Enhanced Raman Spectroscopy

by Vincenz Sandfort¹, Barbara M. Trabold², Amir Abdolvand^2,3, Carsten Bolwien⁴, Philip St. J. Russell², Jürgen Wöllenstein^1,4 and Stefan Palzer^5,*

¹ Laboratory for Gas Sensors, Department of Microsystems Engineering–IMTEK, University of Freiburg, Georges-Köhler-Allee 102, 79110 Freiburg, Germany

² Max Planck Institute for the Science of Light, Staudtstraße 2, 91058 Erlangen, Germany

³ School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Ave, Singapore 639798, Singapore

⁴ Fraunhofer Institute for Physical Measurement Techniques IPM, Heidenhofstraße 8, 79110 Freiburg, Germany

⁵ Department of Computer Science, Universidad Autónoma de Madrid, Francisco Tomás y Valiente 11, 28049 Madrid, Spain

Sensors 2017, 17(12), 2714; https://doi.org/10.3390/s17122714 - 24 Nov 2017

Cited by 37 | Viewed by 12611

Abstract

The fast and reliable analysis of the natural gas composition requires the simultaneous quantification of numerous gaseous components. To this end, fiber-enhanced Raman spectroscopy is a powerful tool to detect most components in a single measurement using a single laser source. However, practical [...] Read more.

The fast and reliable analysis of the natural gas composition requires the simultaneous quantification of numerous gaseous components. To this end, fiber-enhanced Raman spectroscopy is a powerful tool to detect most components in a single measurement using a single laser source. However, practical issues such as detection limit, gas exchange time and background Raman signals from the fiber material still pose obstacles to utilizing the scheme in real-world settings. This paper compares the performance of two types of hollow-core photonic crystal fiber (PCF), namely photonic bandgap PCF and kagomé-style PCF, and assesses their potential for online determination of the Wobbe index. In contrast to bandgap PCF, kagomé-PCF allows for reliable detection of Raman-scattered photons even below 1200 cm⁻¹, which in turn enables fast and comprehensive assessment of the natural gas quality of arbitrary mixtures. Full article

(This article belongs to the Special Issue Spectroscopy Based Sensors)

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14 pages, 4728 KiB

Open AccessArticle

Portable Electronic Nose Based on Electrochemical Sensors for Food Quality Assessment

by Wojciech Wojnowski^1,*

, Tomasz Majchrzak¹

, Tomasz Dymerski¹, Jacek Gębicki² and Jacek Namieśnik¹

¹ Department of Analytical Chemistry, Faculty of Chemistry, Gdańsk University of Technology, 80-233 Gdańsk, Poland

² Department of Chemical and Process Engineering, Faculty of Chemistry, Gdańsk University of Technology, 80-233 Gdańsk, Poland

Sensors 2017, 17(12), 2715; https://doi.org/10.3390/s17122715 - 24 Nov 2017

Cited by 129 | Viewed by 10996

Abstract

The steady increase in global consumption puts a strain on agriculture and might lead to a decrease in food quality. Currently used techniques of food analysis are often labour-intensive and time-consuming and require extensive sample preparation. For that reason, there is a demand [...] Read more.

The steady increase in global consumption puts a strain on agriculture and might lead to a decrease in food quality. Currently used techniques of food analysis are often labour-intensive and time-consuming and require extensive sample preparation. For that reason, there is a demand for novel methods that could be used for rapid food quality assessment. A technique based on the use of an array of chemical sensors for holistic analysis of the sample’s headspace is called electronic olfaction. In this article, a prototype of a portable, modular electronic nose intended for food analysis is described. Using the SVM method, it was possible to classify samples of poultry meat based on shelf-life with 100% accuracy, and also samples of rapeseed oil based on the degree of thermal degradation with 100% accuracy. The prototype was also used to detect adulterations of extra virgin olive oil with rapeseed oil with 82% overall accuracy. Due to the modular design, the prototype offers the advantages of solutions targeted for analysis of specific food products, at the same time retaining the flexibility of application. Furthermore, its portability allows the device to be used at different stages of the production and distribution process. Full article

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

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15 pages, 3997 KiB

Open AccessArticle

A Functionalized Tetrakis(4-Nitrophenyl)Porphyrin Film Optical Waveguide Sensor for Detection of H₂S and Ethanediamine Gases

by Gulimire Tuerdi, Nuerguli Kari

, Yin Yan, Patima Nizamidin and Abliz Yimit^*

College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046, China

Sensors 2017, 17(12), 2717; https://doi.org/10.3390/s17122717 - 24 Nov 2017

Cited by 23 | Viewed by 6253 | Correction

Abstract

The detection of hydrogen sulfide (H₂S) and ethanediamine, toxic gases that are emitted from industrial processes, is important for health and safety. An optical sensor, based on the absorption spectrum of tetrakis(4-nitrophenyl)porphyrin (TNPP) immobilized in a Nafion membrane (Nf) and deposited [...] Read more.

The detection of hydrogen sulfide (H₂S) and ethanediamine, toxic gases that are emitted from industrial processes, is important for health and safety. An optical sensor, based on the absorption spectrum of tetrakis(4-nitrophenyl)porphyrin (TNPP) immobilized in a Nafion membrane (Nf) and deposited onto an optical waveguide glass slide, has been developed for the detection of these gases. Responses to analytes were compared for sensors modified with TNPP and Nf-TNPP composites. Among them, Nf-TNPP exhibited significant responses to H₂S and ethanediamine. The analytical performance characteristics of the Nf-TNPP-modified sensor were investigated and the response mechanism is discussed in detail. The sensor exhibited excellent reproducibilities, reversibilities, and selectivities, with detection limits for H₂S and ethanediamine of 1 and 10 ppb, respectively, and it is a promising candidate for use in industrial sensing applications. Full article

(This article belongs to the Special Issue Nanostructured Hybrid Materials Based Opto-Electronics Sensors)

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12 pages, 819 KiB

Open AccessArticle

Direction-Of-Arrival Estimation and Tracking Based on a Sequential Implementation of C-SPICE with an Off-Grid Model

by Shu Cai^1,*

, Xiaoye Shi² and Hongbo Zhu¹

¹ Jiangsu Key Laboratory of Wireless Communication, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

² School of Internet of things, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

Sensors 2017, 17(12), 2718; https://doi.org/10.3390/s17122718 - 24 Nov 2017

Cited by 7 | Viewed by 4261

Abstract

This paper focuses on the problem of estimating and tracking time-varying direction-of-arrivals (DoAs) with an antenna array. A sequential DoA estimation method is proposed by extending the capon and sparse iterative covariance-based estimation (C-SPICE) method, which is an iterative off-grid method for estimating [...] Read more.

This paper focuses on the problem of estimating and tracking time-varying direction-of-arrivals (DoAs) with an antenna array. A sequential DoA estimation method is proposed by extending the capon and sparse iterative covariance-based estimation (C-SPICE) method, which is an iterative off-grid method for estimating constant DoAs. Then, a moving average initialization technique is introduced such that the spatial spectrum information estimated in this snapshot can be utilized in the next one. In uniform linear arrays (ULAs), we replace the uniform grid in direction domain with that in a “frequency” domain, to improve estimation accuracy without additional complexity in practical applications. The validity and efficiency of the proposed methods are demonstrated through numerical experiments. Full article

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

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18 pages, 7315 KiB

Open AccessArticle

Robust Vehicle Detection in Aerial Images Based on Cascaded Convolutional Neural Networks

by Jiandan Zhong^1,2,3,*

, Tao Lei¹

and Guangle Yao^1,2,3

¹ Institute of Optics and Electronics, Chinese Academy of Sciences, No. 1, Guangdian Avenue, Chengdu 610209, China

² School of Optoelectronic Information, University of Electronic Science and Technology of China, No. 4, Section 2, North Jianshe Road, Chengdu 610054, China

³ University of Chinese Academy of Sciences, 19 A Yuquan Rd, Shijingshan District, Beijing 100039, China

Sensors 2017, 17(12), 2720; https://doi.org/10.3390/s17122720 - 24 Nov 2017

Cited by 77 | Viewed by 8219

Abstract

Vehicle detection in aerial images is an important and challenging task. Traditionally, many target detection models based on sliding-window fashion were developed and achieved acceptable performance, but these models are time-consuming in the detection phase. Recently, with the great success of convolutional neural [...] Read more.

Vehicle detection in aerial images is an important and challenging task. Traditionally, many target detection models based on sliding-window fashion were developed and achieved acceptable performance, but these models are time-consuming in the detection phase. Recently, with the great success of convolutional neural networks (CNNs) in computer vision, many state-of-the-art detectors have been designed based on deep CNNs. However, these CNN-based detectors are inefficient when applied in aerial image data due to the fact that the existing CNN-based models struggle with small-size object detection and precise localization. To improve the detection accuracy without decreasing speed, we propose a CNN-based detection model combining two independent convolutional neural networks, where the first network is applied to generate a set of vehicle-like regions from multi-feature maps of different hierarchies and scales. Because the multi-feature maps combine the advantage of the deep and shallow convolutional layer, the first network performs well on locating the small targets in aerial image data. Then, the generated candidate regions are fed into the second network for feature extraction and decision making. Comprehensive experiments are conducted on the Vehicle Detection in Aerial Imagery (VEDAI) dataset and Munich vehicle dataset. The proposed cascaded detection model yields high performance, not only in detection accuracy but also in detection speed. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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9 pages, 2841 KiB

Open AccessArticle

A Method for Measurement of Nonlinearity of Laser Interferometer Based on Optical Frequency Tuning

by Zhenyu Zhu^1,2,*, Xing Fu¹, Dongmei Ren², Yu Wan² and Ji Wang¹

¹ College of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China

² Changcheng Institute of Metrology & Measurement, Beijing, 100095, China

Sensors 2017, 17(12), 2721; https://doi.org/10.3390/s17122721 - 24 Nov 2017

Cited by 5 | Viewed by 5483

Abstract

A method for measuring the nonlinearity of laser interferometer using optical frequency tuning technique is presented in this paper. The basic principle of this method is to make the fractional part of an interference fringe change by tuning the laser frequency and determining [...] Read more.

A method for measuring the nonlinearity of laser interferometer using optical frequency tuning technique is presented in this paper. The basic principle of this method is to make the fractional part of an interference fringe change by tuning the laser frequency and determining the nonlinearity of interferometer by comparing the fractional fringe change measured by the interferometer to that calculated from the laser frequency change. An experimental interferometric system with a wavelength tunable laser source is set up and the nonlinearity of the interferometer is measured. Since it does not require the precise displacement mechanism to produce the optical path difference change, this method is more convenient to use and may achieve a higher accuracy than the conventional measurement methods. The nonlinearity of the arbitrary interferometric phase can be measured by changing the laser frequency with this method. Experiments results have shown that the repeatability of nonlinearity measurement is less than 0.2 nm. This method can be applied to interferometry-based high precision dimensional measurements, such as coordinate measurement and displacement sensor calibration. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 2379 KiB

Open AccessArticle

Optimization of a Focusable and Rotatable Shear-Wave Periodic Permanent Magnet Electromagnetic Acoustic Transducers for Plates Inspection

by Xiaochun Song^*

and Gongzhe Qiu

School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China

Sensors 2017, 17(12), 2722; https://doi.org/10.3390/s17122722 - 24 Nov 2017

Cited by 34 | Viewed by 4355

Abstract

Due to the symmetry of conventional periodic-permanent-magnet electromagnetic acoustic transducers (PPM EMATs), two shear (SH) waves can be generated and propagated simultaneously in opposite directions, which makes the signal recognition and interpretation complicatedly. Thus, this work presents a new SH wave PPM EMAT [...] Read more.

Due to the symmetry of conventional periodic-permanent-magnet electromagnetic acoustic transducers (PPM EMATs), two shear (SH) waves can be generated and propagated simultaneously in opposite directions, which makes the signal recognition and interpretation complicatedly. Thus, this work presents a new SH wave PPM EMAT design, rotating the parallel line sources to realize the wave beam focusing in a single-direction. The theoretical model of distributed line sources was deduced firstly, and the effects of some parameters, such as the inner coil width, adjacent line sources spacing and the angle between parallel line sources, on SH wave focusing and directivity were studied mainly with the help of 3D FEM. Employing the proposed PPM EMATs, some experiments are carried out to verify the reliability of FEM simulation. The results indicate that rotating the parallel line sources can strength the wave on the closing side of line sources, decreasing the inner coil width and the adjacent line sources spacing can improve the amplitude and directivity of signals excited by transducers. Compared with traditional PPM EMATs, both the capacity of unidirectional excitation and directivity of the proposed PPM EMATs are improved significantly. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 1316 KiB

Open AccessArticle

LSPR Coupling and Distribution of Interparticle Distances between Nanoparticles in Hydrogel on Optical Fiber End Face

by Harald Ian Muri^*

and Dag Roar Hjelme

Department of Electronic Systems, Norwegian University of Science and Technology, Gunnerus gate 1, 7012 Trondheim, Norway

Sensors 2017, 17(12), 2723; https://doi.org/10.3390/s17122723 - 25 Nov 2017

Cited by 30 | Viewed by 6671

Abstract

We report on a new localized surface plasmon resonance (LSPR)-based optical fiber (OF) architecture with a potential in sensor applications. The LSPR-OF system is fabricated by immobilizing gold nanoparticles (GNPs) in a hydrogel droplet polymerized on the fiber end face. This design has [...] Read more.

We report on a new localized surface plasmon resonance (LSPR)-based optical fiber (OF) architecture with a potential in sensor applications. The LSPR-OF system is fabricated by immobilizing gold nanoparticles (GNPs) in a hydrogel droplet polymerized on the fiber end face. This design has several advantages over earlier designs. It dramatically increase the number nanoparticles (NP) available for sensing, it offers precise control over the NP density, and the NPs are positioned in a true 3D aqueous environment. The OF-hydrogel design is also compatible with low-cost manufacturing. The LSPR-OF platform can measure volumetric changes in a stimuli-responsive hydrogel or measure binding to receptors on the NP surface. It can also be used as a two-parameter sensor by utilizing both effects. We present results from proof-of-concept experiments exploring the properties of LSPR and interparticle distances of the GNP-hydrogel OF design by characterizing the distribution of distances between NPs in the hydrogel, the refractive index of the hydrogel and the LSPR attributes of peak position, amplitude and linewidth for hydrogel deswelling controlled with pH solutions. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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18 pages, 6160 KiB

Open AccessArticle

GNSS/Electronic Compass/Road Segment Information Fusion for Vehicle-to-Vehicle Collision Avoidance Application

by Rui Sun^1,2,*

, Qi Cheng¹, Dabin Xue¹, Guanyu Wang¹ and Washington Yotto Ochieng^1,3

¹ College of Civil Aviation, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China

² State Key Laboratory of Geo-Information Engineering, Xi’an 710054, China

³ Centre for Transport Studies, Imperial College London, London SW7 2AZ, UK

Sensors 2017, 17(12), 2724; https://doi.org/10.3390/s17122724 - 25 Nov 2017

Cited by 6 | Viewed by 5645

Abstract

The increasing number of vehicles in modern cities brings the problem of increasing crashes. One of the applications or services of Intelligent Transportation Systems (ITS) conceived to improve safety and reduce congestion is collision avoidance. This safety critical application requires sub-meter level vehicle [...] Read more.

The increasing number of vehicles in modern cities brings the problem of increasing crashes. One of the applications or services of Intelligent Transportation Systems (ITS) conceived to improve safety and reduce congestion is collision avoidance. This safety critical application requires sub-meter level vehicle state estimation accuracy with very high integrity, continuity and availability, to detect an impending collision and issue a warning or intervene in the case that the warning is not heeded. Because of the challenging city environment, to date there is no approved method capable of delivering this high level of performance in vehicle state estimation. In particular, the current Global Navigation Satellite System (GNSS) based collision avoidance systems have the major limitation that the real-time accuracy of dynamic state estimation deteriorates during abrupt acceleration and deceleration situations, compromising the integrity of collision avoidance. Therefore, to provide the Required Navigation Performance (RNP) for collision avoidance, this paper proposes a novel Particle Filter (PF) based model for the integration or fusion of real-time kinematic (RTK) GNSS position solutions with electronic compass and road segment data used in conjunction with an Autoregressive (AR) motion model. The real-time vehicle state estimates are used together with distance based collision avoidance algorithms to predict potential collisions. The algorithms are tested by simulation and in the field representing a low density urban environment. The results show that the proposed algorithm meets the horizontal positioning accuracy requirement for collision avoidance and is superior to positioning accuracy of GNSS only, traditional Constant Velocity (CV) and Constant Acceleration (CA) based motion models, with a significant improvement in the prediction accuracy of potential collision. Full article

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

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24 pages, 5885 KiB

Open AccessArticle

Adaptive Spatial Filter Based on Similarity Indices to Preserve the Neural Information on EEG Signals during On-Line Processing

by Denis Delisle-Rodriguez^1,2,*,‡

, Ana Cecilia Villa-Parra^1,3,†

, Teodiano Bastos-Filho^1,*,‡

, Alberto López-Delis², Anselmo Frizera-Neto^1,‡

, Sridhar Krishnan⁴ and Eduardo Rocon⁵

¹ Postgraduate Program in Electrical Engineering, Federal University of Espirito Santo, 29075-910 Vitoria, Brazil

² Center of Medical Biophysics, University of Oriente, 90500 Santiago de Cuba, Cuba

³ Biomedical Engineering Research Group GIIB, Universidad Politécnica Salesiana, 010105 Cuenca, Ecuador

⁴ Department of Electrical and Computer Engineering, Ryerson University, Toronto, ON M5B 2K3, Canada

⁵ Centre for Automation and Robotics, CSIC-UPM, 28500 Madrid, Spain

^† Current address: Federal University of Espirito Santo, Av. Fernando Ferrari, 514, 29075-910 Vitoria, Brazil.

^‡ These authors contributed equally to this work.

Sensors 2017, 17(12), 2725; https://doi.org/10.3390/s17122725 - 25 Nov 2017

Cited by 24 | Viewed by 8592

Abstract

This work presents a new on-line adaptive filter, which is based on a similarity analysis between standard electrode locations, in order to reduce artifacts and common interferences throughout electroencephalography (EEG) signals, but preserving the useful information. Standard deviation and Concordance Correlation Coefficient (CCC) [...] Read more.

This work presents a new on-line adaptive filter, which is based on a similarity analysis between standard electrode locations, in order to reduce artifacts and common interferences throughout electroencephalography (EEG) signals, but preserving the useful information. Standard deviation and Concordance Correlation Coefficient (CCC) between target electrodes and its correspondent neighbor electrodes are analyzed on sliding windows to select those neighbors that are highly correlated. Afterwards, a model based on CCC is applied to provide higher values of weight to those correlated electrodes with lower similarity to the target electrode. The approach was applied to brain computer-interfaces (BCIs) based on Canonical Correlation Analysis (CCA) to recognize 40 targets of steady-state visual evoked potential (SSVEP), providing an accuracy (ACC) of 86.44 ± 2.81%. In addition, also using this approach, features of low frequency were selected in the pre-processing stage of another BCI to recognize gait planning. In this case, the recognition was significantly

(p < 0.01)

improved for most of the subjects

(A C C \geq 74.79 %)

, when compared with other BCIs based on Common Spatial Pattern, Filter Bank-Common Spatial Pattern, and Riemannian Geometry. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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20 pages, 2543 KiB

Open AccessArticle

Dimension Reduction Aided Hyperspectral Image Classification with a Small-sized Training Dataset: Experimental Comparisons

by Jinya Su^1,*,†

, Dewei Yi^1,†

, Cunjia Liu¹

, Lei Guo² and Wen-Hua Chen¹

¹ Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough LE11 3TU, UK

² School of Electrical Engineering and Automation, Beihang University, Beijing 100191, China

^† These two authors contribute equally to this paper.

Sensors 2017, 17(12), 2726; https://doi.org/10.3390/s17122726 - 25 Nov 2017

Cited by 47 | Viewed by 6072

Abstract

Hyperspectral images (HSI) provide rich information which may not be captured by other sensing technologies and therefore gradually find a wide range of applications. However, they also generate a large amount of irrelevant or redundant data for a specific task. This causes a [...] Read more.

Hyperspectral images (HSI) provide rich information which may not be captured by other sensing technologies and therefore gradually find a wide range of applications. However, they also generate a large amount of irrelevant or redundant data for a specific task. This causes a number of issues including significantly increased computation time, complexity and scale of prediction models mapping the data to semantics (e.g., classification), and the need of a large amount of labelled data for training. Particularly, it is generally difficult and expensive for experts to acquire sufficient training samples in many applications. This paper addresses these issues by exploring a number of classical dimension reduction algorithms in machine learning communities for HSI classification. To reduce the size of training dataset, feature selection (e.g., mutual information, minimal redundancy maximal relevance) and feature extraction (e.g., Principal Component Analysis (PCA), Kernel PCA) are adopted to augment a baseline classification method, Support Vector Machine (SVM). The proposed algorithms are evaluated using a real HSI dataset. It is shown that PCA yields the most promising performance in reducing the number of features or spectral bands. It is observed that while significantly reducing the computational complexity, the proposed method can achieve better classification results over the classic SVM on a small training dataset, which makes it suitable for real-time applications or when only limited training data are available. Furthermore, it can also achieve performances similar to the classic SVM on large datasets but with much less computing time. Full article

(This article belongs to the Special Issue Analysis of Multispectral and Hyperspectral Data)

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22 pages, 1259 KiB

Open AccessArticle

Economic Feasibility of Wireless Sensor Network-Based Service Provision in a Duopoly Setting with a Monopolist Operator

by Angel Sanchis-Cano^1,*

, Julián Romero¹, Erwin J. Sacoto-Cabrera^1,2 and Luis Guijarro¹

¹ ITACA, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain

² GIHP4C, Universidad Politécnica Salesiana-Sede Cuenca, Calle Vieja 12-30 y Elia Liut, 010102 Cuenca, Ecuador

Sensors 2017, 17(12), 2727; https://doi.org/10.3390/s17122727 - 25 Nov 2017

Cited by 8 | Viewed by 5960

Abstract

We analyze the feasibility of providing Wireless Sensor Network-data-based services in an Internet of Things scenario from an economical point of view. The scenario has two competing service providers with their own private sensor networks, a network operator and final users. The scenario [...] Read more.

We analyze the feasibility of providing Wireless Sensor Network-data-based services in an Internet of Things scenario from an economical point of view. The scenario has two competing service providers with their own private sensor networks, a network operator and final users. The scenario is analyzed as two games using game theory. In the first game, sensors decide to subscribe or not to the network operator to upload the collected sensing-data, based on a utility function related to the mean service time and the price charged by the operator. In the second game, users decide to subscribe or not to the sensor-data-based service of the service providers based on a Logit discrete choice model related to the quality of the data collected and the subscription price. The sinks and users subscription stages are analyzed using population games and discrete choice models, while network operator and service providers pricing stages are analyzed using optimization and Nash equilibrium concepts respectively. The model is shown feasible from an economic point of view for all the actors if there are enough interested final users and opens the possibility of developing more efficient models with different types of services. Full article

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

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24 pages, 7290 KiB

Open AccessArticle

New Possibilities of Substance Identification Based on THz Time Domain Spectroscopy Using a Cascade Mechanism of High Energy Level Excitation

by Vyacheslav A. Trofimov^1,*, Svetlana A. Varentsova¹, Irina G. Zakharova^1,2 and Dmitry Yu. Zagursky^1,2

¹ Faculty of Computational Mathematics and Cybernetics, Lomonosov Moscow State University, Leninskiye Gory, Moscow 119992, Russia

² Faculty of Physics, Lomonosov Moscow State University, Leninskiye Gory, Moscow 119992, Russia

Sensors 2017, 17(12), 2728; https://doi.org/10.3390/s17122728 - 25 Nov 2017

Cited by 4 | Viewed by 3642

Abstract

Using an experiment with thin paper layers and computer simulation, we demonstrate the principal limitations of standard Time Domain Spectroscopy (TDS) based on using a broadband THz pulse for the detection and identification of a substance placed inside a disordered structure. We demonstrate [...] Read more.

Using an experiment with thin paper layers and computer simulation, we demonstrate the principal limitations of standard Time Domain Spectroscopy (TDS) based on using a broadband THz pulse for the detection and identification of a substance placed inside a disordered structure. We demonstrate the spectrum broadening of both transmitted and reflected pulses due to the cascade mechanism of the high energy level excitation considering, for example, a three-energy level medium. The pulse spectrum in the range of high frequencies remains undisturbed in the presence of a disordered structure. To avoid false absorption frequencies detection, we apply the spectral dynamics analysis method (SDA-method) together with certain integral correlation criteria (ICC). Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 710 KiB

Open AccessArticle

Autonomous Shepherding Behaviors of Multiple Target Steering Robots

by Wonki Lee and DaeEun Kim^*

Biological Cybernetics Lab, School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea

Sensors 2017, 17(12), 2729; https://doi.org/10.3390/s17122729 - 25 Nov 2017

Cited by 60 | Viewed by 6281

Abstract

This paper presents a distributed coordination methodology for multi-robot systems, based on nearest-neighbor interactions. Among many interesting tasks that may be performed using swarm robots, we propose a biologically-inspired control law for a shepherding task, whereby a group of external agents drives another [...] Read more.

This paper presents a distributed coordination methodology for multi-robot systems, based on nearest-neighbor interactions. Among many interesting tasks that may be performed using swarm robots, we propose a biologically-inspired control law for a shepherding task, whereby a group of external agents drives another group of agents to a desired location. First, we generated sheep-like robots that act like a flock. We assume that each agent is capable of measuring the relative location and velocity to each of its neighbors within a limited sensing area. Then, we designed a control strategy for shepherd-like robots that have information regarding where to go and a steering ability to control the flock, according to the robots’ position relative to the flock. We define several independent behavior rules; each agent calculates to what extent it will move by summarizing each rule. The flocking sheep agents detect the steering agents and try to avoid them; this tendency leads to movement of the flock. Each steering agent only needs to focus on guiding the nearest flocking agent to the desired location. Without centralized coordination, multiple steering agents produce an arc formation to control the flock effectively. In addition, we propose a new rule for collecting behavior, whereby a scattered flock or multiple flocks are consolidated. From simulation results with multiple robots, we show that each robot performs actions for the shepherding behavior, and only a few steering agents are needed to control the whole flock. The results are displayed in maps that trace the paths of the flock and steering robots. Performance is evaluated via time cost and path accuracy to demonstrate the effectiveness of this approach. Full article

(This article belongs to the Special Issue Sensors, Wireless Connectivity and Systems for Autonomous Vehicles and Smart Mobility)

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24 pages, 7001 KiB

Open AccessArticle

A 2.5D Map-Based Mobile Robot Localization via Cooperation of Aerial and Ground Robots

by Tae Hyeon Nam¹, Jae Hong Shim^2,* and Young Im Cho^3,*

¹ Department of Mechatronics Engineering, Graduate School, Korea Polytechnic University, Si-Heung City 15073, Korea

² Department of Mechatronics Engineering, Korea Polytechnic University, Si-Heung City 15073, Korea

³ Department of Computer Engineering, Gachon University, Sung-Nam 13120, Korea

Sensors 2017, 17(12), 2730; https://doi.org/10.3390/s17122730 - 25 Nov 2017

Cited by 28 | Viewed by 10850

Abstract

Recently, there has been increasing interest in studying the task coordination of aerial and ground robots. When a robot begins navigation in an unknown area, it has no information about the surrounding environment. Accordingly, for robots to perform tasks based on location information, [...] Read more.

Recently, there has been increasing interest in studying the task coordination of aerial and ground robots. When a robot begins navigation in an unknown area, it has no information about the surrounding environment. Accordingly, for robots to perform tasks based on location information, they need a simultaneous localization and mapping (SLAM) process that uses sensor information to draw a map of the environment, while simultaneously estimating the current location of the robot on the map. This paper aims to present a localization method based in cooperation between aerial and ground robots in an indoor environment. The proposed method allows a ground robot to reach accurate destination by using a 2.5D elevation map built by a low-cost RGB-D (Red Green and Blue-Depth) sensor and 2D Laser sensor attached onto an aerial robot. A 2.5D elevation map is formed by projecting height information of an obstacle using depth information obtained by the RGB-D sensor onto a grid map, which is generated by using the 2D Laser sensor and scan matching. Experimental results demonstrate the effectiveness of the proposed method for its accuracy in location recognition and computing speed. Full article

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

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18 pages, 1717 KiB

Open AccessArticle

Optimal Power Allocation Strategy in a Joint Bistatic Radar and Communication System Based on Low Probability of Intercept

by Chenguang Shi^1,†

, Fei Wang^1,*,†, Sana Salous^2,† and Jianjiang Zhou^1,†

¹ Key Laboratory of Radar Imaging and Microwave Photonics, Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China

² School of Engineering and Computing Sciences, Durham University, Durham DH1 3DE, UK

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2731; https://doi.org/10.3390/s17122731 - 25 Nov 2017

Cited by 15 | Viewed by 6385

Abstract

In this paper, we investigate a low probability of intercept (LPI)-based optimal power allocation strategy for a joint bistatic radar and communication system, which is composed of a dedicated transmitter, a radar receiver, and a communication receiver. The joint system is capable of [...] Read more.

In this paper, we investigate a low probability of intercept (LPI)-based optimal power allocation strategy for a joint bistatic radar and communication system, which is composed of a dedicated transmitter, a radar receiver, and a communication receiver. The joint system is capable of fulfilling the requirements of both radar and communications simultaneously. First, assuming that the signal-to-noise ratio (SNR) corresponding to the target surveillance path is much weaker than that corresponding to the line of sight path at radar receiver, the analytically closed-form expression for the probability of false alarm is calculated, whereas the closed-form expression for the probability of detection is not analytically tractable and is approximated due to the fact that the received signals are not zero-mean Gaussian under target presence hypothesis. Then, an LPI-based optimal power allocation strategy is presented to minimize the total transmission power for information signal and radar waveform, which is constrained by a specified information rate for the communication receiver and the desired probabilities of detection and false alarm for the radar receiver. The well-known bisection search method is employed to solve the resulting constrained optimization problem. Finally, numerical simulations are provided to reveal the effects of several system parameters on the power allocation results. It is also demonstrated that the LPI performance of the joint bistatic radar and communication system can be markedly improved by utilizing the proposed scheme. Full article

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

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11 pages, 2491 KiB

Open AccessArticle

Pre-Clinical Tests of an Integrated CMOS Biomolecular Sensor for Cardiac Diseases Diagnosis

by Jen-Kuang Lee^1,2,3,4,†, I-Shun Wang^5,†

, Chi-Hsien Huang⁶

, Yih-Fan Chen⁷

, Nien-Tsu Huang¹

and Chih-Ting Lin^1,5,*

¹ Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei 10617, Taiwan

² Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei 10048, Taiwan

³ Telehealth Center, National Taiwan University Hospital, Taipei 10048, Taiwan

⁴ Department of Laboratory Medicine, National Taiwan University Hospital, Taipei 10048, Taiwan

⁵ Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan

⁶ Department of Materials Engineering, Ming Chi University of Technology, New Taipei 24301, Taiwan

⁷ Insisute of Biophotonics, National Yang-Ming University, Taipei 11221, Taiwan

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2733; https://doi.org/10.3390/s17122733 - 26 Nov 2017

Cited by 10 | Viewed by 5722

Abstract

Coronary artery disease and its related complications pose great threats to human health. In this work, we aim to clinically evaluate a CMOS field-effect biomolecular sensor for cardiac biomarkers, cardiac-specific troponin-I (cTnI), N-terminal prohormone brain natriuretic peptide (NT-proBNP), and interleukin-6 (IL-6). The [...] Read more.

Coronary artery disease and its related complications pose great threats to human health. In this work, we aim to clinically evaluate a CMOS field-effect biomolecular sensor for cardiac biomarkers, cardiac-specific troponin-I (cTnI), N-terminal prohormone brain natriuretic peptide (NT-proBNP), and interleukin-6 (IL-6). The CMOS biosensor is implemented via a standard commercialized 0.35 μm CMOS process. To validate the sensing characteristics, in buffer conditions, the developed CMOS biosensor has identified the detection limits of IL-6, cTnI, and NT-proBNP as being 45 pM, 32 pM, and 32 pM, respectively. In clinical serum conditions, furthermore, the developed CMOS biosensor performs a good correlation with an enzyme-linked immuno-sorbent assay (ELISA) obtained from a hospital central laboratory. Based on this work, the CMOS field-effect biosensor poses good potential for accomplishing the needs of a point-of-care testing (POCT) system for heart disease diagnosis. Full article

(This article belongs to the Special Issue Sensors for Health Monitoring and Disease Diagnosis)

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13 pages, 2710 KiB

Open AccessFeature PaperArticle

Screen-Printed Graphite Electrodes as Low-Cost Devices for Oxygen Gas Detection in Room-Temperature Ionic Liquids

by Junqiao Lee¹, Ghulam Hussain¹

, Craig E. Banks²

and Debbie S. Silvester^1,*

¹ Curtin Institute for Functional Molecules and Interfaces & Department of Chemistry, Curtin University, GPO Box U1987, Perth, WA 6845, Australia

² Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK

Sensors 2017, 17(12), 2734; https://doi.org/10.3390/s17122734 - 26 Nov 2017

Cited by 19 | Viewed by 8325

Abstract

Screen-printed graphite electrodes (SPGEs) have been used for the first time as platforms to detect oxygen gas in room-temperature ionic liquids (RTILs). Up until now, carbon-based SPEs have shown inferior behaviour compared to platinum and gold SPEs for gas sensing with RTIL solvents. [...] Read more.

Screen-printed graphite electrodes (SPGEs) have been used for the first time as platforms to detect oxygen gas in room-temperature ionic liquids (RTILs). Up until now, carbon-based SPEs have shown inferior behaviour compared to platinum and gold SPEs for gas sensing with RTIL solvents. The electrochemical reduction of oxygen (O₂) in a range of RTILs has therefore been explored on home-made SPGEs, and is compared to the behaviour on commercially-available carbon SPEs (C-SPEs). Six common RTILs are initially employed for O₂ detection using cyclic voltammetry (CV), and two RTILs ([C₂mim][NTf₂] and [C₄mim][PF₆]) chosen for further detailed analytical studies. Long-term chronoamperometry (LTCA) was also performed to test the ability of the sensor surface for real-time gas monitoring. Both CV and LTCA gave linear calibration graphs—for CV in the 10–100% vol. range, and for LTCA in the 0.1–20% vol. range—on the SPGE. The responses on the SPGE were far superior to the commercial C-SPEs; more instability in the electrochemical responses were observed on the C-SPEs, together with some breaking-up or dissolution of the electrode surface materials. This study highlights that not all screen-printed ink formulations are compatible with RTIL solvents for longer-term electrochemical experiments, and that the choice of RTIL is also important. Overall, the low-cost SPGEs appear to be promising platforms for the detection of O₂, particularly in [C₄mim][PF₆]. Full article

(This article belongs to the Collection Gas Sensors)

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22 pages, 2158 KiB

Open AccessArticle

IMU-Based Gait Recognition Using Convolutional Neural Networks and Multi-Sensor Fusion

by Omid Dehzangi, Mojtaba Taherisadr^*

and Raghvendar ChangalVala

Computer and Information Science Department, University of Michigan-Dearborn, Dearborn, MI 48128, USA

Sensors 2017, 17(12), 2735; https://doi.org/10.3390/s17122735 - 27 Nov 2017

Cited by 169 | Viewed by 15842

Abstract

The wide spread usage of wearable sensors such as in smart watches has provided continuous access to valuable user generated data such as human motion that could be used to identify an individual based on his/her motion patterns such as, gait. Several methods [...] Read more.

The wide spread usage of wearable sensors such as in smart watches has provided continuous access to valuable user generated data such as human motion that could be used to identify an individual based on his/her motion patterns such as, gait. Several methods have been suggested to extract various heuristic and high-level features from gait motion data to identify discriminative gait signatures and distinguish the target individual from others. However, the manual and hand crafted feature extraction is error prone and subjective. Furthermore, the motion data collected from inertial sensors have complex structure and the detachment between manual feature extraction module and the predictive learning models might limit the generalization capabilities. In this paper, we propose a novel approach for human gait identification using time-frequency (TF) expansion of human gait cycles in order to capture joint 2 dimensional (2D) spectral and temporal patterns of gait cycles. Then, we design a deep convolutional neural network (DCNN) learning to extract discriminative features from the 2D expanded gait cycles and jointly optimize the identification model and the spectro-temporal features in a discriminative fashion. We collect raw motion data from five inertial sensors placed at the chest, lower-back, right hand wrist, right knee, and right ankle of each human subject synchronously in order to investigate the impact of sensor location on the gait identification performance. We then present two methods for early (input level) and late (decision score level) multi-sensor fusion to improve the gait identification generalization performance. We specifically propose the minimum error score fusion (MESF) method that discriminatively learns the linear fusion weights of individual DCNN scores at the decision level by minimizing the error rate on the training data in an iterative manner. 10 subjects participated in this study and hence, the problem is a 10-class identification task. Based on our experimental results, 91% subject identification accuracy was achieved using the best individual IMU and 2DTF-DCNN. We then investigated our proposed early and late sensor fusion approaches, which improved the gait identification accuracy of the system to 93.36% and 97.06%, respectively. Full article

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

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48 pages, 7765 KiB

Open AccessArticle

Analysis of Sources of Large Positioning Errors in Deterministic Fingerprinting

by Joaquín Torres-Sospedra^1,*,†

and Adriano Moreira^2,*,†

¹ Institute of New Imaging Technologies, Universitat Jaume I, 12071 Castellón de la Plana, Spain

² Algoritmi Research Centre, University of Minho, 4800-058 Guimarães, Portugal

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2736; https://doi.org/10.3390/s17122736 - 27 Nov 2017

Cited by 43 | Viewed by 7709

Abstract

Wi-Fi fingerprinting is widely used for indoor positioning and indoor navigation due to the ubiquity of wireless networks, high proliferation of Wi-Fi-enabled mobile devices, and its reasonable positioning accuracy. The assumption is that the position can be estimated based on the received signal [...] Read more.

Wi-Fi fingerprinting is widely used for indoor positioning and indoor navigation due to the ubiquity of wireless networks, high proliferation of Wi-Fi-enabled mobile devices, and its reasonable positioning accuracy. The assumption is that the position can be estimated based on the received signal strength intensity from multiple wireless access points at a given point. The positioning accuracy, within a few meters, enables the use of Wi-Fi fingerprinting in many different applications. However, it has been detected that the positioning error might be very large in a few cases, which might prevent its use in applications with high accuracy positioning requirements. Hybrid methods are the new trend in indoor positioning since they benefit from multiple diverse technologies (Wi-Fi, Bluetooth, and Inertial Sensors, among many others) and, therefore, they can provide a more robust positioning accuracy. In order to have an optimal combination of technologies, it is crucial to identify when large errors occur and prevent the use of extremely bad positioning estimations in hybrid algorithms. This paper investigates why large positioning errors occur in Wi-Fi fingerprinting and how to detect them by using the received signal strength intensities. Full article

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

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18 pages, 3013 KiB

Open AccessArticle

A Strategic Bargaining Game for a Spectrum Sharing Scheme in Cognitive Radio-Based Heterogeneous Wireless Sensor Networks

by Yuxing Mao¹

, Tao Cheng^1,*

, Huiyuan Zhao¹

and Na Shen²

¹ School of Electrical Engineering, Chongqing University, Chongqing 400044, China

² School of Nursing, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China

Sensors 2017, 17(12), 2737; https://doi.org/10.3390/s17122737 - 27 Nov 2017

Cited by 9 | Viewed by 4535

Abstract

In Wireless Sensor Networks (WSNs), unlicensed users, that is, sensor nodes, have excessively exploited the unlicensed radio spectrum. Through Cognitive Radio (CR), licensed radio spectra, which are owned by licensed users, can be partly or entirely shared with unlicensed users. This paper proposes [...] Read more.

In Wireless Sensor Networks (WSNs), unlicensed users, that is, sensor nodes, have excessively exploited the unlicensed radio spectrum. Through Cognitive Radio (CR), licensed radio spectra, which are owned by licensed users, can be partly or entirely shared with unlicensed users. This paper proposes a strategic bargaining spectrum-sharing scheme, considering a CR-based heterogeneous WSN (HWSN). The sensors of HWSNs are discrepant and exist in different wireless environments, which leads to various signal-to-noise ratios (SNRs) for the same or different licensed users. Unlicensed users bargain with licensed users regarding the spectrum price. In each round of bargaining, licensed users are allowed to adaptively adjust their spectrum price to the best for maximizing their profits. . Then, each unlicensed user makes their best response and informs licensed users of “bargaining” and “warning”. Through finite rounds of bargaining, this scheme can obtain a Nash bargaining solution (NBS), which makes all licensed and unlicensed users reach an agreement. The simulation results demonstrate that the proposed scheme can quickly find a NBS and all players in the game prefer to be honest. The proposed scheme outperforms existing schemes, within a certain range, in terms of fairness and trade success probability. Full article

(This article belongs to the Special Issue Cognitive Radio Sensing and Sensor Networks)

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15 pages, 2165 KiB

Open AccessArticle

On-Tree Mango Fruit Size Estimation Using RGB-D Images

by Zhenglin Wang¹, Kerry B. Walsh^2,*

and Brijesh Verma¹

¹ Centre for Intelligent Systems, Central Queensland University, Rockhampton, Queensland 4701, Australia

² Institute for Future Farming Systems, Central Queensland University, Rockhampton, Queensland 4701, Australia

Sensors 2017, 17(12), 2738; https://doi.org/10.3390/s17122738 - 28 Nov 2017

Cited by 162 | Viewed by 14622

Abstract

In-field mango fruit sizing is useful for estimation of fruit maturation and size distribution, informing the decision to harvest, harvest resourcing (e.g., tray insert sizes), and marketing. In-field machine vision imaging has been used for fruit count, but assessment of fruit size from [...] Read more.

In-field mango fruit sizing is useful for estimation of fruit maturation and size distribution, informing the decision to harvest, harvest resourcing (e.g., tray insert sizes), and marketing. In-field machine vision imaging has been used for fruit count, but assessment of fruit size from images also requires estimation of camera-to-fruit distance. Low cost examples of three technologies for assessment of camera to fruit distance were assessed: a RGB-D (depth) camera, a stereo vision camera and a Time of Flight (ToF) laser rangefinder. The RGB-D camera was recommended on cost and performance, although it functioned poorly in direct sunlight. The RGB-D camera was calibrated, and depth information matched to the RGB image. To detect fruit, a cascade detection with histogram of oriented gradients (HOG) feature was used, then Otsu’s method, followed by color thresholding was applied in the CIE L*a*b* color space to remove background objects (leaves, branches etc.). A one-dimensional (1D) filter was developed to remove the fruit pedicles, and an ellipse fitting method employed to identify well-separated fruit. Finally, fruit lineal dimensions were calculated using the RGB-D depth information, fruit image size and the thin lens formula. A Root Mean Square Error (RMSE) = 4.9 and 4.3 mm was achieved for estimated fruit length and width, respectively, relative to manual measurement, for which repeated human measures were characterized by a standard deviation of 1.2 mm. In conclusion, the RGB-D method for rapid in-field mango fruit size estimation is practical in terms of cost and ease of use, but cannot be used in direct intense sunshine. We believe this work represents the first practical implementation of machine vision fruit sizing in field, with practicality gauged in terms of cost and simplicity of operation. Full article

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

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9 pages, 1654 KiB

Open AccessArticle

Colorectal Cancer and Colitis Diagnosis Using Fourier Transform Infrared Spectroscopy and an Improved K-Nearest-Neighbour Classifier

by Qingbo Li^1,*, Can Hao¹, Xue Kang¹, Jialin Zhang¹, Xuejun Sun², Wenbo Wang³ and Haishan Zeng³

¹ School of Instrumentation Science and Opto-Electronics Engineering, Precision Opto-Mechatronics Technology Key Laboratory of Education Ministry, Beihang University, Xueyuan Road No. 37, Haidian District, Beijing 100191, China

² Department of General Surgery, First Hospital of Xi’an Jiaotong University, Xi’an 710061, China

³ Cancer Imaging Unit—Integrative Oncology Department, BC Cancer Agency Research Centre, Vancouver, BC V5Z 1L3, Canada

Sensors 2017, 17(12), 2739; https://doi.org/10.3390/s17122739 - 27 Nov 2017

Cited by 25 | Viewed by 4556

Abstract

Combining Fourier transform infrared spectroscopy (FTIR) with endoscopy, it is expected that noninvasive, rapid detection of colorectal cancer can be performed in vivo in the future. In this study, Fourier transform infrared spectra were collected from 88 endoscopic biopsy colorectal tissue samples (41 [...] Read more.

Combining Fourier transform infrared spectroscopy (FTIR) with endoscopy, it is expected that noninvasive, rapid detection of colorectal cancer can be performed in vivo in the future. In this study, Fourier transform infrared spectra were collected from 88 endoscopic biopsy colorectal tissue samples (41 colitis and 47 cancers). A new method, viz., entropy weight local-hyperplane k-nearest-neighbor (EWHK), which is an improved version of K-local hyperplane distance nearest-neighbor (HKNN), is proposed for tissue classification. In order to avoid limiting high dimensions and small values of the nearest neighbor, the new EWHK method calculates feature weights based on information entropy. The average results of the random classification showed that the EWHK classifier for differentiating cancer from colitis samples produced a sensitivity of 81.38% and a specificity of 92.69%. Full article

(This article belongs to the Section Biosensors)

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8 pages, 2418 KiB

Open AccessArticle

Mn-Doped CaBi₄Ti₄O₁₅/Pb(Zr,Ti)O₃ Ultrasonic Transducers for Continuous Monitoring at Elevated Temperatures

by Makiko Kobayashi^1,*

, Taiga Kibe¹ and Hajime Nagata²

¹ Faculty of Advanced Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan

² Department of Electrical Engineering, Tokyo University of Science, Tokyo 162-0825, Japan

Sensors 2017, 17(12), 2740; https://doi.org/10.3390/s17122740 - 27 Nov 2017

Cited by 2 | Viewed by 3913

Abstract

Continuous ultrasonic in-situ monitoring for industrial applications is difficult owing to the high operating temperatures in industrial fields. It is expected that ultrasonic transducers consisting of a CaBi₄Ti₄O₁₅(CBT)/Pb(Zr,Ti)O₃(PZT) sol-gel composite could be one solution for [...] Read more.

Continuous ultrasonic in-situ monitoring for industrial applications is difficult owing to the high operating temperatures in industrial fields. It is expected that ultrasonic transducers consisting of a CaBi₄Ti₄O₁₅(CBT)/Pb(Zr,Ti)O₃(PZT) sol-gel composite could be one solution for ultrasonic nondestructive testing (NDT) above 500 °C because no couplant is required and CBT has a high Curie temperature. To verify the high temperature durability, CBT/PZT sol-gel composite films were fabricated on titanium substrates by spray coating, and the CBT/PZT samples were tested in a furnace at various temperatures. Reflected echoes with a high signal-to-noise ratio were observed up to 600 °C. A thermal cycle test was conducted from room temperature to 600 °C, and no significant deterioration was found after the second thermal cycle. To investigate the long-term high-temperature durability, a CBT/PZT ultrasonic transducer was tested in the furnace at 600 °C for 36 h. Ultrasonic responses were recorded every 3 h, and the sensitivity and signal-to-noise ratio were stable throughout the experiment. Full article

(This article belongs to the Special Issue Materials and Applications for Sensors and Transducers)

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31 pages, 11928 KiB

Open AccessArticle

Adapting Local Features for Face Detection in Thermal Image

by Chao Ma^1,*, Ngo Thanh Trung², Hideaki Uchiyama¹, Hajime Nagahara³, Atsushi Shimada¹ and Rin-ichiro Taniguchi¹

¹ Graduate School of Information Science and Electrical Engineering, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan

² The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

³ Institute for Datability Science, Osaka University, 2-8, Yamadaoka, Suita, Osaka 565-0871, Japan

Sensors 2017, 17(12), 2741; https://doi.org/10.3390/s17122741 - 27 Nov 2017

Cited by 30 | Viewed by 7694

Abstract

A thermal camera captures the temperature distribution of a scene as a thermal image. In thermal images, facial appearances of different people under different lighting conditions are similar. This is because facial temperature distribution is generally constant and not affected by lighting condition. [...] Read more.

A thermal camera captures the temperature distribution of a scene as a thermal image. In thermal images, facial appearances of different people under different lighting conditions are similar. This is because facial temperature distribution is generally constant and not affected by lighting condition. This similarity in face appearances is advantageous for face detection. To detect faces in thermal images, cascade classifiers with Haar-like features are generally used. However, there are few studies exploring the local features for face detection in thermal images. In this paper, we introduce two approaches relying on local features for face detection in thermal images. First, we create new feature types by extending Multi-Block LBP. We consider a margin around the reference and the generally constant distribution of facial temperature. In this way, we make the features more robust to image noise and more effective for face detection in thermal images. Second, we propose an AdaBoost-based training method to get cascade classifiers with multiple types of local features. These feature types have different advantages. In this way we enhance the description power of local features. We did a hold-out validation experiment and a field experiment. In the hold-out validation experiment, we captured a dataset from 20 participants, comprising 14 males and 6 females. For each participant, we captured 420 images with 10 variations in camera distance, 21 poses, and 2 appearances (participant with/without glasses). We compared the performance of cascade classifiers trained by different sets of the features. The experiment results showed that the proposed approaches effectively improve the performance of face detection in thermal images. In the field experiment, we compared the face detection performance in realistic scenes using thermal and RGB images, and gave discussion based on the results. 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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17 pages, 4139 KiB

Open AccessArticle

Dynamic Obstacle Avoidance for Unmanned Underwater Vehicles Based on an Improved Velocity Obstacle Method

by Wei Zhang, Shilin Wei^*, Yanbin Teng, Jianku Zhang, Xiufang Wang and Zheping Yan

Marine Assembly and Automatic Technology Institute, College of Automation, Harbin Engineering University; Harbin 150001, China

Sensors 2017, 17(12), 2742; https://doi.org/10.3390/s17122742 - 27 Nov 2017

Cited by 57 | Viewed by 8799

Abstract

In view of a dynamic obstacle environment with motion uncertainty, we present a dynamic collision avoidance method based on the collision risk assessment and improved velocity obstacle method. First, through the fusion optimization of forward-looking sonar data, the redundancy of the data is [...] Read more.

In view of a dynamic obstacle environment with motion uncertainty, we present a dynamic collision avoidance method based on the collision risk assessment and improved velocity obstacle method. First, through the fusion optimization of forward-looking sonar data, the redundancy of the data is reduced and the position, size and velocity information of the obstacles are obtained, which can provide an accurate decision-making basis for next-step collision avoidance. Second, according to minimum meeting time and the minimum distance between the obstacle and unmanned underwater vehicle (UUV), this paper establishes the collision risk assessment model, and screens key obstacles to avoid collision. Finally, the optimization objective function is established based on the improved velocity obstacle method, and a UUV motion characteristic is used to calculate the reachable velocity sets. The optimal collision speed of UUV is searched in velocity space. The corresponding heading and speed commands are calculated, and outputted to the motion control module. The above is the complete dynamic obstacle avoidance process. The simulation results show that the proposed method can obtain a better collision avoidance effect in the dynamic environment, and has good adaptability to the unknown dynamic environment. Full article

(This article belongs to the Special Issue Smart Sensors for Mechatronic and Robotic Systems)

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12 pages, 5081 KiB

Open AccessArticle

Effect of Composition and Thickness on the Perpendicular Magnetic Anisotropy of (Co/Pd) Multilayers

by Bharati Tudu^1,2, Kun Tian¹ and Ashutosh Tiwari^1,*

¹ Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84112, USA

² Department of Physics, Jadavpur University, Kolkata-700032, India

Sensors 2017, 17(12), 2743; https://doi.org/10.3390/s17122743 - 28 Nov 2017

Cited by 22 | Viewed by 7857

Abstract

Magnetic materials with perpendicular magnetic anisotropy (PMA) have wide-ranging applications in magnetic recording and sensing devices. Multilayers comprised of ferromagnetic and non-magnetic metals (FM–NM) are interesting materials, as their magnetic anisotropy depends strongly on composition and growth parameters. In this context, (Co/Pd) multilayers [...] Read more.

Magnetic materials with perpendicular magnetic anisotropy (PMA) have wide-ranging applications in magnetic recording and sensing devices. Multilayers comprised of ferromagnetic and non-magnetic metals (FM–NM) are interesting materials, as their magnetic anisotropy depends strongly on composition and growth parameters. In this context, (Co/Pd) multilayers have gained huge interest recently due to their robustness and tunable PMA. Here, we report a systematic study of the effect of composition on the magnetic anisotropy of (Co/Pd) multilayers grown by Direct Current (DC) magnetron sputtering. Four different series of (Co/Pd)_×10 multilayers with different thicknesses of Co and Pd were examined. Vibrating sample magnetometery was used to determine the magnetic anisotropy of these films. X-ray diffraction and transmission electron microscopy experiments were performed to understand the structural morphology of the films. Our results showed that (Co/Pd)_×10 multilayers exhibit PMA when the Co to Pd ratio is less than or equal to 1 and the thickness of Co layers is not more than 5 Å. Maximum effective anisotropy energy is shown by the films with a Co to Pd ratio of 1/3. Full article

(This article belongs to the Special Issue Magnetic Sensors and Their Applications)

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11 pages, 6346 KiB

Open AccessArticle

All-Fiber Laser Curvature Sensor Using an In-Fiber Modal Interferometer Based on a Double Clad Fiber and a Multimode Fiber Structure

by Ricardo I. Álvarez-Tamayo¹

, Manuel Durán-Sánchez^2,*, Patricia Prieto-Cortés³, Guillermo Salceda-Delgado³, Arturo A. Castillo-Guzmán³, Romeo Selvas-Aguilar³, Baldemar Ibarra-Escamilla⁴ and Evgeny A. Kuzin⁴

¹ CONACYT—FCFM, Universidad Autónoma de Nuevo León, Av. Universidad S/N, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León 66455, Mexico

² CONACYT—Optics department, Instituto Nacional de Astrofísica, Óptica y Electrónica, L. E. Erro 1, Sta. Ma. Tonantzintla, Puebla 72824, Mexico

³ FCFM, Universidad Autónoma de Nuevo León, Av. Universidad S/N, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León 66455, Mexico

⁴ Optics Department, Instituto Nacional de Astrofísica, Óptica y Electrónica, L. E. Erro 1, Sta. Ma. Tonantzintla, Puebla 72824, Mexico

Sensors 2017, 17(12), 2744; https://doi.org/10.3390/s17122744 - 28 Nov 2017

Cited by 21 | Viewed by 5461

Abstract

An all-fiber curvature laser sensor by using a novel modal interference in-fiber structure is proposed and experimentally demonstrated. The in-fiber device, fabricated by fusion splicing of multimode fiber and double-clad fiber segments, is used as wavelength filter as well as the sensing element. [...] Read more.

An all-fiber curvature laser sensor by using a novel modal interference in-fiber structure is proposed and experimentally demonstrated. The in-fiber device, fabricated by fusion splicing of multimode fiber and double-clad fiber segments, is used as wavelength filter as well as the sensing element. By including a multimode fiber in an ordinary modal interference structure based on a double-clad fiber, the fringe visibility of the filter transmission spectrum is significantly increased. By using the modal interferometer as a curvature sensitive wavelength filter within a ring cavity erbium-doped fiber laser, the spectral quality factor Q is considerably increased. The results demonstrate the reliability of the proposed curvature laser sensor with advantages of robustness, ease of fabrication, low cost, repeatability on the fabrication process and simple operation. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2017)

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20 pages, 6751 KiB

Open AccessArticle

Development of a High Precision Displacement Measurement System by Fusing a Low Cost RTK-GPS Sensor and a Force Feedback Accelerometer for Infrastructure Monitoring

by Gunhee Koo¹

, Kiyoung Kim¹

, Jun Yeon Chung¹

, Jaemook Choi¹

, Nam-Yeol Kwon², Doo-Young Kang² and Hoon Sohn^1,*

¹ Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea

² Poongsan FNS Corporation, Nonsan 33003, Korea

Sensors 2017, 17(12), 2745; https://doi.org/10.3390/s17122745 - 28 Nov 2017

Cited by 28 | Viewed by 7901

Abstract

A displacement measurement system fusing a low cost real-time kinematic global positioning system (RTK-GPS) receiver and a force feedback accelerometer is proposed for infrastructure monitoring. The proposed system is composed of a sensor module, a base module and a computation module. The sensor [...] Read more.

A displacement measurement system fusing a low cost real-time kinematic global positioning system (RTK-GPS) receiver and a force feedback accelerometer is proposed for infrastructure monitoring. The proposed system is composed of a sensor module, a base module and a computation module. The sensor module consists of a RTK-GPS rover and a force feedback accelerometer, and is installed on a target structure like conventional RTK-GPS sensors. The base module is placed on a rigid ground away from the target structure similar to conventional RTK-GPS bases, and transmits observation messages to the sensor module. Then, the initial acceleration, velocity and displacement responses measured by the sensor module are transmitted to the computation module located at a central monitoring facility. Finally, high precision and high sampling rate displacement, velocity, and acceleration are estimated by fusing the acceleration from the accelerometer, the velocity from the GPS rover, and the displacement from RTK-GPS. Note that the proposed displacement measurement system can measure 3-axis acceleration, velocity as well as displacement in real time. In terms of displacement, the proposed measurement system can estimate dynamic and pseudo-static displacement with a root-mean-square error of 2 mm and a sampling rate of up to 100 Hz. The performance of the proposed system is validated under sinusoidal, random and steady-state vibrations. Field tests were performed on the Yeongjong Grand Bridge and Yi Sun-sin Bridge in Korea, and the Xihoumen Bridge in China to compare the performance of the proposed system with a commercial RTK-GPS sensor and other data fusion techniques. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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17 pages, 3563 KiB

Open AccessArticle

Radio-Frequency-Controlled Urea Dosing for NH₃-SCR Catalysts: NH₃ Storage Influence to Catalyst Performance under Transient Conditions

by Markus Dietrich^1,2, Gunter Hagen¹, Willibald Reitmeier², Katharina Burger², Markus Hien², Philippe Grass², David Kubinski³, Jaco Visser³ and Ralf Moos^1,*

¹ Bayreuth Engine Research Center (BERC), Department of Functional Materials, University of Bayreuth, 95447 Bayreuth, Germany

² Continental Automotive GmbH, Division Powertrain, 93055 Regensburg, Germany

³ Ford Research and Innovation Center, Dearborn, MI 48124, USA

Sensors 2017, 17(12), 2746; https://doi.org/10.3390/s17122746 - 28 Nov 2017

Cited by 7 | Viewed by 7477

Abstract

Current developments in exhaust gas aftertreatment led to a huge mistrust in diesel driven passenger cars due to their NO_x emissions being too high. The selective catalytic reduction (SCR) with ammonia (NH₃) as reducing agent is the only approach today [...] Read more.

Current developments in exhaust gas aftertreatment led to a huge mistrust in diesel driven passenger cars due to their NO_x emissions being too high. The selective catalytic reduction (SCR) with ammonia (NH₃) as reducing agent is the only approach today with the capability to meet upcoming emission limits. Therefore, the radio-frequency-based (RF) catalyst state determination to monitor the NH₃ loading on SCR catalysts has a huge potential in emission reduction. Recent work on this topic proved the basic capability of this technique under realistic conditions on an engine test bench. In these studies, an RF system calibration for the serial type SCR catalyst Cu-SSZ-13 was developed and different approaches for a temperature dependent NH₃ storage were determined. This paper continues this work and uses a fully calibrated RF-SCR system under transient conditions to compare different directly measured and controlled NH₃ storage levels, and NH₃ target curves. It could be clearly demonstrated that the right NH₃ target curve, together with a direct control on the desired level by the RF system, is able to operate the SCR system with the maximum possible NO_x conversion efficiency and without NH₃ slip. Full article

(This article belongs to the Section Chemical Sensors)

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14 pages, 6395 KiB

Open AccessArticle

A Quartz Crystal Microbalance Immunosensor for Stem Cell Selection and Extraction

by Ornella Maglio^1,2

, Salvatore Costanzo^1,†, Rosaria Cercola^1,‡

, Gerardo Zambrano¹, Marco Mauro³, Raffaele Battaglia³, Gianluca Ferrini³, Flavia Nastri¹, Vincenzo Pavone¹ and Angela Lombardi^1,*

¹ Department of Chemical Sciences, University of Napoli “Federico II” Via Cintia, 80126 Napoli, Italy

² Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, 80134 Napoli, Italy

³ Novaetech S.r.l., Centro Direzionale, Isola G7, 80143 Napoli, Italy

^† Current address: Faculty of Chemistry, University Pierre et Marie Curie, 4 Place Jussieu, 75005 Paris, France.

^‡ Current address: Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.

Sensors 2017, 17(12), 2747; https://doi.org/10.3390/s17122747 - 28 Nov 2017

Cited by 24 | Viewed by 14879

Abstract

A cost-effective immunosensor for the detection and isolation of dental pulp stem cells (DPSCs) based on a quartz crystal microbalance (QCM) has been developed. The recognition mechanism relies on anti-CD34 antibodies, DPSC-specific monoclonal antibodies that are anchored on the surface of the quartz [...] Read more.

A cost-effective immunosensor for the detection and isolation of dental pulp stem cells (DPSCs) based on a quartz crystal microbalance (QCM) has been developed. The recognition mechanism relies on anti-CD34 antibodies, DPSC-specific monoclonal antibodies that are anchored on the surface of the quartz crystals. Due to its high specificity, real time detection, and low cost, the proposed technology has a promising potential in the field of cell biology, for the simultaneous detection and sorting of stem cells from heterogeneous cell samples. The QCM surface was properly tailored through a biotinylated self-assembled monolayer (SAM). The biotin–avidin interaction was used to immobilize the biotinylated anti-CD34 antibody on the gold-coated quartz crystal. After antibody immobilization, a cellular pellet, with a mixed cell population, was analyzed; the results indicated that the developed QCM immunosensor is highly specific, being able to detect and sort only CD34+ cells. Our study suggests that the proposed technology can detect and efficiently sort any kind of cell from samples with high complexity, being simple, selective, and providing for more convenient and time-saving operations. Full article

(This article belongs to the Special Issue Dedication to Professor Eiichi Tamiya: Over 30 Years of Outstanding Contributions to the Field of Sensors and Biosensors)

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14 pages, 2687 KiB

Open AccessArticle

Tactile Perception of Roughness and Hardness to Discriminate Materials by Friction-Induced Vibration

by Shuyang Ding

, Yunlu Pan^*

, Mingsi Tong

and Xuezeng Zhao^*

Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education and School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China

Sensors 2017, 17(12), 2748; https://doi.org/10.3390/s17122748 - 28 Nov 2017

Cited by 44 | Viewed by 8730

Abstract

The human fingertip is an exquisitely powerful bio-tactile sensor in perceiving different materials based on various highly-sensitive mechanoreceptors distributed all over the skin. The tactile perception of surface roughness and material hardness can be estimated by skin vibrations generated during a fingertip stroking [...] Read more.

The human fingertip is an exquisitely powerful bio-tactile sensor in perceiving different materials based on various highly-sensitive mechanoreceptors distributed all over the skin. The tactile perception of surface roughness and material hardness can be estimated by skin vibrations generated during a fingertip stroking of a surface instead of being maintained in a static position. Moreover, reciprocating sliding with increasing velocities and pressures are two common behaviors in humans to discriminate different materials, but the question remains as to what the correlation of the sliding velocity and normal load on the tactile perceptions of surface roughness and hardness is for material discrimination. In order to investigate this correlation, a finger-inspired crossed-I beam structure tactile tester has been designed to mimic the anthropic tactile discrimination behaviors. A novel method of characterizing the fast Fourier transform integral (FFT) slope of the vibration acceleration signal generated from fingertip rubbing on surfaces at increasing sliding velocity and normal load, respectively, are defined as k_v and k_w, and is proposed to discriminate the surface roughness and hardness of different materials. Over eight types of materials were tested, and they proved the capability and advantages of this high tactile-discriminating method. Our study may find applications in investigating humanoid robot perceptual abilities. Full article

(This article belongs to the Special Issue Tactile Sensors and Sensing)

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14 pages, 6581 KiB

Open AccessArticle

Mathematical Model for Localised and Surface Heat Flux of the Human Body Obtained from Measurements Performed with a Calorimetry Minisensor

by Fabiola Socorro, Pedro Jesús Rodríguez de Rivera, Miriam Rodríguez de Rivera and Manuel Rodríguez de Rivera^*

Departamento de Física, Universidad de Las Palmas de Gran Canaria, E-35017 Las Palmas de Gran Canaria, Spain

Sensors 2017, 17(12), 2749; https://doi.org/10.3390/s17122749 - 28 Nov 2017

Cited by 8 | Viewed by 5794

Abstract

The accuracy of the direct and local measurements of the heat power dissipated by the surface of the human body, using a calorimetry minisensor, is directly related to the calibration rigor of the sensor and the correct interpretation of the experimental results. For [...] Read more.

The accuracy of the direct and local measurements of the heat power dissipated by the surface of the human body, using a calorimetry minisensor, is directly related to the calibration rigor of the sensor and the correct interpretation of the experimental results. For this, it is necessary to know the characteristics of the body’s local heat dissipation. When the sensor is placed on the surface of the human body, the body reacts until a steady state is reached. We propose a mathematical model that represents the rate of heat flow at a given location on the surface of a human body by the sum of a series of exponentials: W(t) = A₀ + ∑A_iexp(−t/τ_i). In this way, transient and steady states of heat dissipation can be interpreted. This hypothesis has been tested by simulating the operation of the sensor. At the steady state, the power detected in the measurement area (4 cm²) varies depending on the sensor’s thermostat temperature, as well as the physical state of the subject. For instance, for a thermostat temperature of 24 °C, this power can vary between 100–250 mW in a healthy adult. In the transient state, two exponentials are sufficient to represent this dissipation, with 3 and 70 s being the mean values of its time constants. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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7 pages, 6575 KiB

Open AccessCommunication

Room-Temperature H₂ Gas Sensing Characterization of Graphene-Doped Porous Silicon via a Facile Solution Dropping Method

by Nu Si A. Eom^1,†

, Hong-Baek Cho^1,†, Yoseb Song¹, Woojin Lee², Tohru Sekino³

and Yong-Ho Choa^1,*

¹ Department of Fusion Chemical Engineering, Hanyang University, Ansan 15588, Korea

² Process Development Team, Semiconductor R&D Center, Samsung Electronics Co., Ltd., Samsungjeonja-ro 1, Hwaseong, Gyeonggi-do 445-330, Korea

³ The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2750; https://doi.org/10.3390/s17122750 - 28 Nov 2017

Cited by 27 | Viewed by 6654

Abstract

In this study, a graphene-doped porous silicon (G-doped/p-Si) substrate for low ppm H₂ gas detection by an inexpensive synthesis route was proposed as a potential noble graphene-based gas sensor material, and to understand the sensing mechanism. The G-doped/p-Si gas sensor was synthesized [...] Read more.

In this study, a graphene-doped porous silicon (G-doped/p-Si) substrate for low ppm H₂ gas detection by an inexpensive synthesis route was proposed as a potential noble graphene-based gas sensor material, and to understand the sensing mechanism. The G-doped/p-Si gas sensor was synthesized by a simple capillary force-assisted solution dropping method on p-Si substrates, whose porosity was generated through an electrochemical etching process. G-doped/p-Si was fabricated with various graphene concentrations and exploited as a H₂ sensor that was operated at room temperature. The sensing mechanism of the sensor with/without graphene decoration on p-Si was proposed to elucidate the synergetic gas sensing effect that is generated from the interface between the graphene and p-type silicon. Full article

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

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18 pages, 2198 KiB

Open AccessArticle

Knee Impedance Modulation to Control an Active Orthosis Using Insole Sensors

by Ana Cecilia Villa-Parra^1,2,*,†

, Denis Delisle-Rodriguez^1,3

, Jessica Souza Lima⁴, Anselmo Frizera-Neto¹

and Teodiano Bastos^1,*

¹ Postgraduate Program in Electrical Engineering, Federal University of Espirito Santo, Vitoria 29075-910, Brazil

² Biomedical Engineering Research Group GIIB, Universidad Politécnica Salesiana, Cuenca 010105, Ecuador

³ Center of Medical Biophysics, University of Oriente, Santiago de Cuba 90500, Cuba

⁴ Postgraduate Program in Biotechnology, Universidade Federal do Espirito Santo, Vitoria 29043-900, Brazil

^† Current address: Av. Fernando Ferrari, 514, Goiabeiras, Vitória CEP 29075-910, Brazil.

Sensors 2017, 17(12), 2751; https://doi.org/10.3390/s17122751 - 28 Nov 2017

Cited by 40 | Viewed by 6918

Abstract

Robotic devices for rehabilitation and gait assistance have greatly advanced with the objective of improving both the mobility and quality of life of people with motion impairments. To encourage active participation of the user, the use of admittance control strategy is one of [...] Read more.

Robotic devices for rehabilitation and gait assistance have greatly advanced with the objective of improving both the mobility and quality of life of people with motion impairments. To encourage active participation of the user, the use of admittance control strategy is one of the most appropriate approaches, which requires methods for online adjustment of impedance components. Such approach is cited by the literature as a challenge to guaranteeing a suitable dynamic performance. This work proposes a method for online knee impedance modulation, which generates variable gains through the gait cycle according to the users’ anthropometric data and gait sub-phases recognized with footswitch signals. This approach was evaluated in an active knee orthosis with three variable gain patterns to obtain a suitable condition to implement a stance controller: two different gain patterns to support the knee in stance phase, and a third pattern for gait without knee support. The knee angle and torque were measured during the experimental protocol to compare both temporospatial parameters and kinematics data with other studies of gait with knee exoskeletons. The users rated scores related to their satisfaction with both the device and controller through QUEST questionnaires. Experimental results showed that the admittance controller proposed here offered knee support in 50% of the gait cycle, and the walking speed was not significantly different between the three gain patterns (p = 0.067). A positive effect of the controller on users regarding safety during gait was found with a score of 4 in a scale of 5. Therefore, the approach demonstrates good performance to adjust impedance components providing knee support in stance phase. Full article

(This article belongs to the Special Issue Assistance Robotics and Biosensors)

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10 pages, 3002 KiB

Open AccessArticle

Effect of Shot Noise on Simultaneous Sensing in Frequency Division Multiplexed Diffuse Optical Tomographic Imaging Process

by Hansol Jang^1,†, Gukbin Lim^1,†, Keum-Shik Hong¹, Jaedu Cho², Gultekin Gulsen² and Chang-Seok Kim^1,*

¹ Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 46241, Korea

² Tu & Yuen Center for Functional Onco-Imaging, Department of Radiological Sciences, University of California, Irvine, CA 92697, USA

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2752; https://doi.org/10.3390/s17122752 - 28 Nov 2017

Cited by 3 | Viewed by 4811

Abstract

Diffuse optical tomography (DOT) has been studied for use in the detection of breast cancer, cerebral oxygenation, and cognitive brain signals. As optical imaging studies have increased significantly, acquiring imaging data in real time has become increasingly important. We have developed frequency-division multiplexing [...] Read more.

Diffuse optical tomography (DOT) has been studied for use in the detection of breast cancer, cerebral oxygenation, and cognitive brain signals. As optical imaging studies have increased significantly, acquiring imaging data in real time has become increasingly important. We have developed frequency-division multiplexing (FDM) DOT systems to analyze their performance with respect to acquisition time and imaging quality, in comparison with the conventional time-division multiplexing (TDM) DOT. A large tomographic area of a cylindrical phantom 60 mm in diameter could be successfully reconstructed using both TDM DOT and FDM DOT systems. In our experiment with 6 source-detector (S-D) pairs, the TDM DOT and FDM DOT systems required 6.18 and 1 s, respectively, to obtain a single tomographic data set. While the absorption coefficient of the reconstruction image was underestimated in the case of the FDM DOT, we experimentally confirmed that the abnormal region can be clearly distinguished from the background phantom using both methods. Full article

(This article belongs to the Special Issue Novel Sensors for Bioimaging)

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20 pages, 5606 KiB

Open AccessArticle

A Novel Adaptive H∞ Filtering Method with Delay Compensation for the Transfer Alignment of Strapdown Inertial Navigation Systems

by Weiwei Lyu^1,2 and Xianghong Cheng^1,2,*

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

² Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology, Ministry of Education, Southeast University, Nanjing 210096, China

Sensors 2017, 17(12), 2753; https://doi.org/10.3390/s17122753 - 28 Nov 2017

Cited by 11 | Viewed by 4204

Abstract

Transfer alignment is always a key technology in a strapdown inertial navigation system (SINS) because of its rapidity and accuracy. In this paper a transfer alignment model is established, which contains the SINS error model and the measurement model. The time delay in [...] Read more.

Transfer alignment is always a key technology in a strapdown inertial navigation system (SINS) because of its rapidity and accuracy. In this paper a transfer alignment model is established, which contains the SINS error model and the measurement model. The time delay in the process of transfer alignment is analyzed, and an H∞ filtering method with delay compensation is presented. Then the H∞ filtering theory and the robust mechanism of H∞ filter are deduced and analyzed in detail. In order to improve the transfer alignment accuracy in SINS with time delay, an adaptive H∞ filtering method with delay compensation is proposed. Since the robustness factor plays an important role in the filtering process and has effect on the filtering accuracy, the adaptive H∞ filter with delay compensation can adjust the value of robustness factor adaptively according to the dynamic external environment. The vehicle transfer alignment experiment indicates that by using the adaptive H∞ filtering method with delay compensation, the transfer alignment accuracy and the pure inertial navigation accuracy can be dramatically improved, which demonstrates the superiority of the proposed filtering method. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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16 pages, 5974 KiB

Open AccessArticle

ECG Signal De-noising and Baseline Wander Correction Based on CEEMDAN and Wavelet Threshold

by Yang Xu^1,2

, Mingzhang Luo^1,2,*, Tao Li^1,2 and Gangbing Song^1,3,*

¹ Electronics & Information School, Yangtze University, Jingzhou 434023, China

² National Demonstration Center for Experimental Electrotechnics and Electronics Education, Yangtze University, Jingzhou 434023, China

³ Department of Mechanical Engineering, University of Houston, Houston, TX 77004, USA

Sensors 2017, 17(12), 2754; https://doi.org/10.3390/s17122754 - 28 Nov 2017

Cited by 105 | Viewed by 10684

Abstract

A novel electrocardiogram (ECG) signal de-noising and baseline wander correction method based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and wavelet threshold is proposed. Although CEEMDAN is based on empirical mode decomposition (EMD), it represents a significant improvement of the [...] Read more.

A novel electrocardiogram (ECG) signal de-noising and baseline wander correction method based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and wavelet threshold is proposed. Although CEEMDAN is based on empirical mode decomposition (EMD), it represents a significant improvement of the original EMD by overcoming the mode-mixing problem. However, there has been no previous study on using CEEMDAN to de-noise ECG signals, to the authors’ best knowledge. In the proposed method, the original noisy ECG signal is decomposed into a series of intrinsic mode functions (IMFs) sorted from high to low frequency by CEEMDAN. Each IMF is then analyzed by the autocorrelation method to find out the first few high frequency IMFs containing random noise, and these IMFs should be de-noised by the wavelet threshold. The zero-crossing rate (ZCR) of all IMFs, including final residue, are computed, and the IMFs with ZCR less than a certain value are removed. Finally, the remaining IMFs are reconstructed to obtain the clean ECG signal. The proposed algorithm is validated through experiments using the MIT–BIH ECG databases, and the results show that the random noise in the ECG signal can be effectively suppressed, and at the same time the baseline wander can be corrected efficiently. Full article

(This article belongs to the Special Issue Sensor Signal and Information Processing)

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17 pages, 6212 KiB

Open AccessArticle

Comprehensive Detection of Gas Plumes from Multibeam Water Column Images with Minimisation of Noise Interferences

by Jianhu Zhao^1,2, Junxia Meng^1,2,*, Hongmei Zhang³ and Shiqi Wang^1,2

¹ Institute of Marine Science and Technology, Wuhan University, Wuhan 430079, China

² School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China

³ School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China

Sensors 2017, 17(12), 2755; https://doi.org/10.3390/s17122755 - 29 Nov 2017

Cited by 25 | Viewed by 5437

Abstract

Multibeam echosounder systems (MBES) can record backscatter strengths of gas plumes in the water column (WC) images that may be an indicator of possible occurrence of gas at certain depths. Manual or automatic detection is generally adopted in finding gas plumes, but frequently [...] Read more.

Multibeam echosounder systems (MBES) can record backscatter strengths of gas plumes in the water column (WC) images that may be an indicator of possible occurrence of gas at certain depths. Manual or automatic detection is generally adopted in finding gas plumes, but frequently results in low efficiency and high false detection rates because of WC images that are polluted by noise. To improve the efficiency and reliability of the detection, a comprehensive detection method is proposed in this paper. In the proposed method, the characteristics of WC background noise are first analyzed and given. Then, the mean standard deviation threshold segmentations are respectively used for the denoising of time-angle and depth-angle images, an intersection operation is performed for the two segmented images to further weaken noise in the WC data, and the gas plumes in the WC data are detected from the intersection image by the morphological constraint. The proposed method was tested by conducting shallow-water and deepwater experiments. In these experiments, the detections were conducted automatically and higher correct detection rates than the traditional methods were achieved. The performance of the proposed method is analyzed and discussed. Full article

(This article belongs to the Section Remote Sensors)

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11 pages, 5805 KiB

Open AccessArticle

First Results of Using a UVTron Flame Sensor to Detect Alpha-Induced Air Fluorescence in the UVC Wavelength Range

by Anita J. Crompton^1,*

, Kelum A. A. Gamage²

, Steven Bell³

, Andrew P. Wilson⁴, Alex Jenkins⁵ and Divyesh Trivedi⁶

¹ Engineering Department, Lancaster University, Lancaster LA1 4YW, UK

² School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK

³ Nuclear Metrology Group, National Physical Laboratory, London TW11 0LW, UK

⁴ Independent researcher, Warrington WA5 9YX, UK

⁵ Characterisation, Inspection & Decontamination Group, Sellafield Ltd., Cumbria CA20 1PG, UK

⁶ The National Nuclear Laboratory, Warrington WA3 6AE, UK

Sensors 2017, 17(12), 2756; https://doi.org/10.3390/s17122756 - 29 Nov 2017

Cited by 16 | Viewed by 6566

Abstract

In this work, a robust stand-off alpha detection method using the secondary effects of alpha radiation has been sought. Alpha particles ionise the surrounding atmosphere as they travel. Fluorescence photons produced as a consequence of this can be used to detect the source [...] Read more.

In this work, a robust stand-off alpha detection method using the secondary effects of alpha radiation has been sought. Alpha particles ionise the surrounding atmosphere as they travel. Fluorescence photons produced as a consequence of this can be used to detect the source of the alpha emissions. This paper details experiments carried out to detect this fluorescence, with the focus on photons in the ultraviolet C (UVC) wavelength range (180–280 nm). A detector, UVTron R9533 (Hamamatsu, 325-6, Sunayama-cho, Naka-ku, Hamamatsu City, Shizuoka Pref., 430-8587, Japan), designed to detect the UVC emissions from flames for fire alarm purposes, was tested in various gas atmospheres with a ²¹⁰Po alpha source to determine if this could provide an avenue for stand-off alpha detection. The results of the experiments show that this detector is capable of detecting alpha-induced air fluorescence in normal indoor lighting conditions, as the interference from daylight and artificial lighting is less influential on this detection system which operates below the UVA and UVB wavelength ranges (280–315 nm and 315–380 nm respectively). Assuming a standard

\frac{1}{r^{2}}

drop off in signal, the limit of detection in this configuration can be calculated to be approximately 240 mm, well beyond the range of alpha-particles in air, which indicates that this approach could have potential for stand-off alpha detection. The gas atmospheres tested produced an increase in the detector count, with xenon having the greatest effect with a measured 52% increase in the detector response in comparison to the detector response in an air atmosphere. This type of alpha detection system could be operated at a distance, where it would potentially provide a more cost effective, safer, and faster solution in comparison with traditional alpha detection methods to detect and characterise alpha contamination in nuclear decommissioning and security applications. Full article

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

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19 pages, 9671 KiB

Open AccessArticle

Depth-Based Detection of Standing-Pigs in Moving Noise Environments

by Jinseong Kim¹, Yeonwoo Chung², Younchang Choi¹, Jaewon Sa¹

, Heegon Kim¹, Yongwha Chung^1,*, Daihee Park¹ and Hakjae Kim³

¹ Department of Computer and Information Science, Korea University, Sejong City 30019, Korea

² Department of Applied Statistics, Korea University, Sejong City 30019, Korea

³ Class Act Co., Ltd., Digital-ro, Geumcheon-gu, Seoul 08589, Korea

Sensors 2017, 17(12), 2757; https://doi.org/10.3390/s17122757 - 29 Nov 2017

Cited by 63 | Viewed by 6853

Abstract

In a surveillance camera environment, the detection of standing-pigs in real-time is an important issue towards the final goal of 24-h tracking of individual pigs. In this study, we focus on depth-based detection of standing-pigs with “moving noises”, which appear every night in [...] Read more.

In a surveillance camera environment, the detection of standing-pigs in real-time is an important issue towards the final goal of 24-h tracking of individual pigs. In this study, we focus on depth-based detection of standing-pigs with “moving noises”, which appear every night in a commercial pig farm, but have not been reported yet. We first apply a spatiotemporal interpolation technique to remove the moving noises occurring in the depth images. Then, we detect the standing-pigs by utilizing the undefined depth values around them. Our experimental results show that this method is effective for detecting standing-pigs at night, in terms of both cost-effectiveness (using a low-cost Kinect depth sensor) and accuracy (i.e., 94.47%), even with severe moving noises occluding up to half of an input depth image. Furthermore, without any time-consuming technique, the proposed method can be executed in real-time. Full article

(This article belongs to the Special Issue Imaging Depth Sensors—Sensors, Algorithms and Applications)

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19 pages, 1922 KiB

Open AccessArticle

An Efficient Audio Coding Scheme for Quantitative and Qualitative Large Scale Acoustic Monitoring Using the Sensor Grid Approach

by Félix Gontier¹, Mathieu Lagrange^1,*, Pierre Aumond^2,3

, Arnaud Can² and Catherine Lavandier³

¹ LS2N, UMR 6004, École Centrale de Nantes, 44300 Nantes, France

² LAE, AME, IFSTTAR, 44340 Bouguenais, France

³ ETIS, UMR 8051, Université Paris Seine, Université de Cergy-Pontoise, ENSEA, CNRS, 95000 Cergy-Pontoise, France

Sensors 2017, 17(12), 2758; https://doi.org/10.3390/s17122758 - 29 Nov 2017

Cited by 12 | Viewed by 5297

Abstract

The spreading of urban areas and the growth of human population worldwide raise societal and environmental concerns. To better address these concerns, the monitoring of the acoustic environment in urban as well as rural or wilderness areas is an important matter. Building on [...] Read more.

The spreading of urban areas and the growth of human population worldwide raise societal and environmental concerns. To better address these concerns, the monitoring of the acoustic environment in urban as well as rural or wilderness areas is an important matter. Building on the recent development of low cost hardware acoustic sensors, we propose in this paper to consider a sensor grid approach to tackle this issue. In this kind of approach, the crucial question is the nature of the data that are transmitted from the sensors to the processing and archival servers. To this end, we propose an efficient audio coding scheme based on third octave band spectral representation that allows: (1) the estimation of standard acoustic indicators; and (2) the recognition of acoustic events at state-of-the-art performance rate. The former is useful to provide quantitative information about the acoustic environment, while the latter is useful to gather qualitative information and build perceptually motivated indicators using for example the emergence of a given sound source. The coding scheme is also demonstrated to transmit spectrally encoded data that, reverted to the time domain using state-of-the-art techniques, are not intelligible, thus protecting the privacy of citizens. Full article

(This article belongs to the Collection Smart Communication Protocols and Algorithms for Sensor Networks)

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10 pages, 2031 KiB

Open AccessArticle

A New Low-Temperature Electrochemical Hydrocarbon and NO_x Sensor

by Praveen Kumar Sekhar^1,*, Zachary Moore¹, Shyam Aravamudhan² and Ajit Khosla³

¹ Nanomaterials and Sensors Laboratory, School of Engineering and Computer Science, Washington State University Vancouver, Vancouver, WA 98686, USA

² Joint School of Nanoscience and Nanoengineering, North Carolina A & T State University, Greensboro, NC 27401, USA

³ Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan

Sensors 2017, 17(12), 2759; https://doi.org/10.3390/s17122759 - 29 Nov 2017

Cited by 25 | Viewed by 6143

Abstract

In this article, a new investigation on a low-temperature electrochemical hydrocarbon and NO_x sensor is presented. Based on the mixed-potential-based sensing scheme, the sensor is constructed using platinum and metal oxide electrodes, along with an Yttria-Stabilized Zirconia (YSZ)/Strontium Titanate (SrTiO₃) [...] Read more.

In this article, a new investigation on a low-temperature electrochemical hydrocarbon and NO_x sensor is presented. Based on the mixed-potential-based sensing scheme, the sensor is constructed using platinum and metal oxide electrodes, along with an Yttria-Stabilized Zirconia (YSZ)/Strontium Titanate (SrTiO₃) thin-film electrolyte. Unlike traditional mixed-potential sensors which operate at higher temperatures (>400 °C), this potentiometric sensor operates at 200 °C with dominant hydrocarbon (HC) and NO_x response in the open-circuit and biased modes, respectively. The possible low-temperature operation of the sensor is speculated to be primarily due to the enhanced oxygen ion conductivity of the electrolyte, which may be attributed to the space charge effect, epitaxial strain, and atomic reconstruction at the interface of the YSZ/STO thin film. The response and recovery time for the NO_x sensor are found to be 7 s and 8 s, respectively. The sensor exhibited stable response even after 120 days of testing, with an 11.4% decrease in HC response and a 3.3% decrease in NO_x response. Full article

(This article belongs to the Special Issue Air Pollution Sensors: A New Class of Tools to Measure Air Quality)

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12 pages, 3928 KiB

Open AccessArticle

Highly Sensitive FPW-Based Microsystem for Rapid Detection of Tetrahydrocannabinol in Human Urine

by Je-Wei Lan¹, Chia-Hsu Hsieh¹, I-Yu Huang¹, Yu-Cheng Lin², Tsung-Yi Tsai¹ and Chua-Chin Wang^1,*

¹ Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung 80424, Taiwan

² Department of Engineering Science, National Cheng Kung University, Tainan 70101, Taiwan

Sensors 2017, 17(12), 2760; https://doi.org/10.3390/s17122760 - 29 Nov 2017

Cited by 6 | Viewed by 4780

Abstract

This paper presents a highly sensitive flexural plate-wave (FPW)-based microsystem for rapid detection of tetrahydrocannabinol (THC) in human urine. First, a circular-type interdigital transducer (IDT) was integrated with a circular-type silicon-grooved reflective grating structure (RGS) to reduce insertion loss. Then, with lower insertion [...] Read more.

This paper presents a highly sensitive flexural plate-wave (FPW)-based microsystem for rapid detection of tetrahydrocannabinol (THC) in human urine. First, a circular-type interdigital transducer (IDT) was integrated with a circular-type silicon-grooved reflective grating structure (RGS) to reduce insertion loss. Then, with lower insertion loss (−38.758 dB), the FPW device was used to develop a novel THC biosensor, and the results reveal that this FPW-THC biosensor has low detection limit (1.5625 ng/mL) and high mass-sensitivity (126.67 cm²/g). Finally, this biosensor was integrated with field-programmable gate array (FPGA) board and discrete components for prototyping a FPW readout system, whose maximum error was 12.378 kHz to ensure that the linearity of detection up to R-square is equal to 0.9992. Full article

(This article belongs to the Special Issue Bio-MEMS for Precision Medicine)

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17 pages, 4142 KiB

Open AccessArticle

A Real-Time Robust Method to Detect BeiDou GEO/IGSO Orbital Maneuvers

by Guanwen Huang, Zhiwei Qin^*, Qin Zhang^*, Le Wang, Xingyuan Yan, Lihong Fan and Xiaolei Wang

College of Geology Engineering and Geomantic, Chang’an University, 126 Yanta Road, Xi’an 710054, China

Sensors 2017, 17(12), 2761; https://doi.org/10.3390/s17122761 - 29 Nov 2017

Cited by 23 | Viewed by 4634

Abstract

The frequent maneuvering of BeiDou Geostationary Orbit (GEO) and Inclined Geosynchronous Orbit (IGSO) satellites affects the availability of real-time orbit, and decreases the accuracy and performance of positioning, navigation and time (PNT) services. BeiDou satellite maneuver information cannot be obtained by common users. [...] Read more.

The frequent maneuvering of BeiDou Geostationary Orbit (GEO) and Inclined Geosynchronous Orbit (IGSO) satellites affects the availability of real-time orbit, and decreases the accuracy and performance of positioning, navigation and time (PNT) services. BeiDou satellite maneuver information cannot be obtained by common users. BeiDou broadcast ephemeris is the only indicator of the health status of satellites, which are broadcast on an hourly basis, easily leading to ineffective observations. Sometimes, identification errors of satellite abnormity also appear in the broadcast ephemeris. This study presents a real-time robust detection method for a satellite orbital maneuver with high frequency and high reliability. By using the broadcast ephemeris and pseudo-range observations, the time discrimination factor and the satellite identification factor were defined and used for the real-time detection of start time and the pseudo-random noise code (PRN) of satellites was used for orbital maneuvers. Data from a Multi-GNSS Experiment (MGEX) was collected and analyzed. The results show that the start time and the PRN of the satellite orbital maneuver could be detected accurately in real time. In addition, abnormal start times and satellite abnormities caused by non-maneuver factors also could be detected using the proposed method. The new method not only improves the utilization of observations for users with the data effective for about 92 min, but also promotes the reliability of real-time PNT services. Full article

(This article belongs to the Section Remote Sensors)

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21 pages, 26800 KiB

Open AccessArticle

GelSight: High-Resolution Robot Tactile Sensors for Estimating Geometry and Force

by Wenzhen Yuan, Siyuan Dong and Edward H. Adelson^*

Computer Science and Artificial Intelligence Laboratory (CSAIL), Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Sensors 2017, 17(12), 2762; https://doi.org/10.3390/s17122762 - 29 Nov 2017

Cited by 792 | Viewed by 50899

Abstract

Tactile sensing is an important perception mode for robots, but the existing tactile technologies have multiple limitations. What kind of tactile information robots need, and how to use the information, remain open questions. We believe a soft sensor surface and high-resolution sensing of [...] Read more.

Tactile sensing is an important perception mode for robots, but the existing tactile technologies have multiple limitations. What kind of tactile information robots need, and how to use the information, remain open questions. We believe a soft sensor surface and high-resolution sensing of geometry should be important components of a competent tactile sensor. In this paper, we discuss the development of a vision-based optical tactile sensor, GelSight. Unlike the traditional tactile sensors which measure contact force, GelSight basically measures geometry, with very high spatial resolution. The sensor has a contact surface of soft elastomer, and it directly measures its deformation, both vertical and lateral, which corresponds to the exact object shape and the tension on the contact surface. The contact force, and slip can be inferred from the sensor’s deformation as well. Particularly, we focus on the hardware and software that support GelSight’s application on robot hands. This paper reviews the development of GelSight, with the emphasis in the sensing principle and sensor design. We introduce the design of the sensor’s optical system, the algorithm for shape, force and slip measurement, and the hardware designs and fabrication of different sensor versions. We also show the experimental evaluation on the GelSight’s performance on geometry and force measurement. With the high-resolution measurement of shape and contact force, the sensor has successfully assisted multiple robotic tasks, including material perception or recognition and in-hand localization for robot manipulation. Full article

(This article belongs to the Special Issue Tactile Sensors and Sensing)

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26 pages, 3257 KiB

Open AccessArticle

Symbiotic Sensing for Energy-Intensive Tasks in Large-Scale Mobile Sensing Applications

by Duc V. Le^1,*,†

, Thuong Nguyen²

, Hans Scholten¹ and Paul J. M. Havinga¹

¹ Pervasive Systems Group, Department of Computer Science, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands

² The Australian e-Health Research Centre, CSIRO, Herston, Queensland 4029, Australia

^† Current address: Zilverling 5007, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands.

Sensors 2017, 17(12), 2763; https://doi.org/10.3390/s17122763 - 29 Nov 2017

Cited by 2 | Viewed by 4621

Abstract

Energy consumption is a critical performance and user experience metric when developing mobile sensing applications, especially with the significantly growing number of sensing applications in recent years. As proposed a decade ago when mobile applications were still not popular and most mobile operating [...] Read more.

Energy consumption is a critical performance and user experience metric when developing mobile sensing applications, especially with the significantly growing number of sensing applications in recent years. As proposed a decade ago when mobile applications were still not popular and most mobile operating systems were single-tasking, conventional sensing paradigms such as opportunistic sensing and participatory sensing do not explore the relationship among concurrent applications for energy-intensive tasks. In this paper, inspired by social relationships among living creatures in nature, we propose a symbiotic sensing paradigm that can conserve energy, while maintaining equivalent performance to existing paradigms. The key idea is that sensing applications should cooperatively perform common tasks to avoid acquiring the same resources multiple times. By doing so, this sensing paradigm executes sensing tasks with very little extra resource consumption and, consequently, extends battery life. To evaluate and compare the symbiotic sensing paradigm with the existing ones, we develop mathematical models in terms of the completion probability and estimated energy consumption. The quantitative evaluation results using various parameters obtained from real datasets indicate that symbiotic sensing performs better than opportunistic sensing and participatory sensing in large-scale sensing applications, such as road condition monitoring, air pollution monitoring, and city noise monitoring. Full article

(This article belongs to the Special Issue Ubiquitous Massive Sensing Using Smartphones)

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19 pages, 1854 KiB

Open AccessArticle

An Advanced Hybrid Technique of DCS and JSRC for Telemonitoring of Multi-Sensor Gait Pattern

by Jianning Wu^*

, Jiajing Wang, Yun Ling and Haidong Xu

College of Mathematics and Informatics, Fujian Normal University, Fuzhou 350117, China

Sensors 2017, 17(12), 2764; https://doi.org/10.3390/s17122764 - 29 Nov 2017

Cited by 4 | Viewed by 4434

Abstract

The jointly quantitative analysis of multi-sensor gait data for the best gait-classification performance has been a challenging endeavor in wireless body area networks (WBANs)-based gait telemonitoring applications. In this study, based on the joint sparsity of data, we proposed an advanced hybrid technique [...] Read more.

The jointly quantitative analysis of multi-sensor gait data for the best gait-classification performance has been a challenging endeavor in wireless body area networks (WBANs)-based gait telemonitoring applications. In this study, based on the joint sparsity of data, we proposed an advanced hybrid technique of distributed compressed sensing (DCS) and joint sparse representation classification (JSRC) for multi-sensor gait classification. Firstly, the DCS technique is utilized to simultaneously compress multi-sensor gait data for capturing spatio-temporal correlation information about gait while the energy efficiency of the sensors is available. Then, the jointly compressed gait data are directly used to develop a novel neighboring sample-based JSRC model by defining the sparse representation coefficients-inducing criterion (SRCC), in order to yield the best classification performance as well as a lower computational time cost. The multi-sensor gait data were selected from an open wearable action recognition database (WARD) to validate the feasibility of our proposed method. The results showed that when the comparison ratio and the number of neighboring samples are selected as 70% and 40%, respectively, the best accuracy (95%) can be reached while the lowest computational time spends only 60 ms. Moreover, the best accuracy and the computational time can increase by 5% and decrease by 40 ms, respectively, when compared with the traditional JSRC techniques. Our proposed hybrid technique can take advantage of the joint sparsity of data for jointly processing multi-sensor gait data, which greatly contributes to the best gait-classification performance. This has great potential for energy-efficient telemonitoring of multi-sensor gait. Full article

(This article belongs to the Special Issue Sensors for Gait, Posture, and Health Monitoring)

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14 pages, 428 KiB

Open AccessArticle

Gold Nanoparticles Used as Protein Scavengers Enhance Surface Plasmon Resonance Signal

by Erenildo Ferreira de Macedo, Daniela Maria Ducatti Formaggio, Nivia Salles Santos and Dayane Batista Tada^*

Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo, Rua Talim 330, Vila Nair, São José dos Campos, SP 12231-280, Brazil

Sensors 2017, 17(12), 2765; https://doi.org/10.3390/s17122765 - 29 Nov 2017

Cited by 16 | Viewed by 5519

Abstract

Although several researchers had reported on methodologies for surface plasmon resonance (SPR) signal amplification based on the use of nanoparticles (NPs), the majority addressed the sandwich technique and low protein concentration. In this work, a different approach for SPR signal enhancement based on [...] Read more.

Although several researchers had reported on methodologies for surface plasmon resonance (SPR) signal amplification based on the use of nanoparticles (NPs), the majority addressed the sandwich technique and low protein concentration. In this work, a different approach for SPR signal enhancement based on the use of gold NPs was evaluated. The method was used in the detection of two lectins, peanut agglutinin (PNA) and concanavalin A (ConA). Gold NPs were functionalized with antibodies anti-PNA and anti-ConA, and these NPs were used as protein scavengers in a solution. After being incubated with solutions of PNA or ConA, the gold NPs coupled with the collected lectins were injected on the sensor containing the immobilized antibodies. The signal amplification provided by this method was compared to the signal amplification provided by the direct coupling of PNA and ConA to gold NPs. Furthermore, both methods, direct coupling and gold NPs as protein scavengers, were compared to the direct detection of PNA and ConA in solution. Compared to the analysis of free protein, the direct coupling of PNA and ConA to gold NPs resulted in a signal amplification of 10–40-fold and a 13-fold decrease of the limit of detection (LOD), whereas the use of gold NPs as protein scavengers resulted in an SPR signal 40–50-times higher and an LOD 64-times lower. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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18 pages, 2423 KiB

Open AccessFeature PaperArticle

A Dependable Localization Algorithm for Survivable Belt-Type Sensor Networks

by Mingqiang Zhu¹, Fei Song¹, Lei Xu², Jung Taek Seo³ and Ilsun You^3,*

¹ School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing 100044, China

² Graduate School, University of International Business and Economics, Beijing 100029, China

³ Department of Information Security Engineering, Soonchunhyang University, Asan-si 31538, Korea

Sensors 2017, 17(12), 2767; https://doi.org/10.3390/s17122767 - 29 Nov 2017

Cited by 2 | Viewed by 4033

Abstract

As the key element, sensor networks are widely investigated by the Internet of Things (IoT) community. When massive numbers of devices are well connected, malicious attackers may deliberately propagate fake position information to confuse the ordinary users and lower the network survivability in [...] Read more.

As the key element, sensor networks are widely investigated by the Internet of Things (IoT) community. When massive numbers of devices are well connected, malicious attackers may deliberately propagate fake position information to confuse the ordinary users and lower the network survivability in belt-type situation. However, most existing positioning solutions only focus on the algorithm accuracy and do not consider any security aspects. In this paper, we propose a comprehensive scheme for node localization protection, which aims to improve the energy-efficient, reliability and accuracy. To handle the unbalanced resource consumption, a node deployment mechanism is presented to satisfy the energy balancing strategy in resource-constrained scenarios. According to cooperation localization theory and network connection property, the parameter estimation model is established. To achieve reliable estimations and eliminate large errors, an improved localization algorithm is created based on modified average hop distances. In order to further improve the algorithms, the node positioning accuracy is enhanced by using the steepest descent method. The experimental simulations illustrate the performance of new scheme can meet the previous targets. The results also demonstrate that it improves the belt-type sensor networks’ survivability, in terms of anti-interference, network energy saving, etc. Full article

(This article belongs to the Special Issue Next Generation Wireless Technologies for Internet of Things)

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15 pages, 5403 KiB

Open AccessArticle

Assessment of Embedded Conjugated Polymer Sensor Arrays for Potential Load Transmission Measurement in Orthopaedic Implants

by Carolina Micolini¹, Frederick Benjamin Holness¹, James A. Johnson² and Aaron David Price^1,*

¹ Organic Mechatronics and Smart Materials Laboratory Mechanical and Materials Engineering, University of Western Ontario, London, ON N6A 5B9, Canada

² Lawson Health Research Institute, University of Western Ontario, London, ON N6C 2R5, Canada

Sensors 2017, 17(12), 2768; https://doi.org/10.3390/s17122768 - 29 Nov 2017

Cited by 8 | Viewed by 5426

Abstract

Load transfer through orthopaedic joint implants is poorly understood. The longer-term outcomes of these implants are just starting to be studied, making it imperative to monitor contact loads across the entire joint implant interface to elucidate the force transmission and distribution mechanisms exhibited [...] Read more.

Load transfer through orthopaedic joint implants is poorly understood. The longer-term outcomes of these implants are just starting to be studied, making it imperative to monitor contact loads across the entire joint implant interface to elucidate the force transmission and distribution mechanisms exhibited by these implants in service. This study proposes and demonstrates the design, implementation, and characterization of a 3D-printed smart polymer sensor array using conductive polyaniline (PANI) structures embedded within a polymeric parent phase. The piezoresistive characteristics of PANI were investigated to characterize the sensing behaviour inherent to these embedded pressure sensor arrays, including the experimental determination of the stable response of PANI to continuous loading, stability throughout the course of loading and unloading cycles, and finally sensor repeatability and linearity in response to incremental loading cycles. This specially developed multi-material additive manufacturing process for PANI is shown be an attractive approach for the fabrication of implant components having embedded smart-polymer sensors, which could ultimately be employed for the measurement and analysis of joint loads in orthopaedic implants for in vitro testing. Full article

(This article belongs to the Special Issue Force and Pressure Based Sensing Medical Application)

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18 pages, 1722 KiB

Open AccessArticle

An Adaptive S-Method to Analyze Micro-Doppler Signals for Human Activity Classification

by Fangmin Li^1,2, Chao Yang^1,*, Yuqing Xia²

, Xiaolin Ma², Tao Zhang¹ and Zhou Zhou¹

¹ Department of Mathematics and Computer Science, Changsha University, Changsha 410022, China

² School of Information Engineering, Wuhan University of Technology, Wuhan 430070, China

Sensors 2017, 17(12), 2769; https://doi.org/10.3390/s17122769 - 29 Nov 2017

Cited by 14 | Viewed by 4461

Abstract

In this paper, we propose the multiwindow Adaptive S-method (AS-method) distribution approach used in the time-frequency analysis for radar signals. Based on the results of orthogonal Hermite functions that have good time-frequency resolution, we vary the length of window to suppress the oscillating [...] Read more.

In this paper, we propose the multiwindow Adaptive S-method (AS-method) distribution approach used in the time-frequency analysis for radar signals. Based on the results of orthogonal Hermite functions that have good time-frequency resolution, we vary the length of window to suppress the oscillating component caused by cross-terms. This method can bring a better compromise in the auto-terms concentration and cross-terms suppressing, which contributes to the multi-component signal separation. Finally, the effective micro signal is extracted by threshold segmentation and envelope extraction. To verify the proposed method, six states of motion are separated by a classifier of a support vector machine (SVM) trained to the extracted features. The trained SVM can detect a human subject with an accuracy of 95.4% for two cases without interference. Full article

(This article belongs to the Section Physical Sensors)

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25 pages, 16072 KiB

Open AccessArticle

Health Diagnosis of Major Transportation Infrastructures in Shanghai Metropolis Using High-Resolution Persistent Scatterer Interferometry

by Xiaoqiong Qin^1,2,3, Mengshi Yang^1,5, Lu Zhang¹

, Tianliang Yang^3,4 and Mingsheng Liao^1,2,3,*

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

² Collaborative Innovation Center for Geospatial Technology, Wuhan University, Wuhan 430079, China

³ Key Laboratory of Land Subsidence Monitoring and Prevention, Ministry of Lanf and Resources, Shanghai 200072, China

⁴ Shanghai Institute of Geological Survey, Shanghai 200072, China

⁵ Department of Geoscience and Remote Sensing, Delft University of Technology, 2628 CN Delft, The Netherlands

Sensors 2017, 17(12), 2770; https://doi.org/10.3390/s17122770 - 29 Nov 2017

Cited by 23 | Viewed by 5062

Abstract

Since the Persistent Scatterer Synthetic Aperture Radar (SAR) Interferometry (PSI) technology allows the detection of ground subsidence with millimeter accuracy, it is becoming one of the most powerful and economical means for health diagnosis of major transportation infrastructures. However, structures of different types [...] Read more.

Since the Persistent Scatterer Synthetic Aperture Radar (SAR) Interferometry (PSI) technology allows the detection of ground subsidence with millimeter accuracy, it is becoming one of the most powerful and economical means for health diagnosis of major transportation infrastructures. However, structures of different types may suffer from various levels of localized subsidence due to the different structural characteristics and subsidence mechanisms. Moreover, in the complex urban scenery, some segments of these infrastructures may be sheltered by surrounding buildings in SAR images, obscuring the desirable signals. Therefore, the subsidence characteristics on different types of structures should be discussed separately and the accuracy of persistent scatterers (PSs) should be optimized. In this study, the PSI-based subsidence mapping over the entire transportation network of Shanghai (more than 10,000 km) is illustrated, achieving the city-wide monitoring specifically along the elevated roads, ground highways and underground subways. The precise geolocation and structural characteristics of infrastructures were combined to effectively guide more accurate identification and separation of PSs along the structures. The experimental results from two neighboring TerraSAR-X stacks from 2013 to 2016 were integrated by joint estimating the measurements in the overlapping area, performing large-scale subsidence mapping and were validated by leveling data, showing highly consistent in terms of subsidence velocities and time-series displacements. Spatial-temporal subsidence patterns on each type of infrastructures are strongly dependent on the operational durations and structural characteristics, as well as the variation of the foundation soil layers. Full article

(This article belongs to the Special Issue Sensors for Deformation Monitoring of Large Civil Infrastructures)

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10 pages, 2459 KiB

Open AccessArticle

Silver Nanoparticle Modified Electrode Covered by Graphene Oxide for the Enhanced Electrochemical Detection of Dopamine

by Jae-Wook Shin¹, Kyeong-Jun Kim¹, Jinho Yoon¹, Jinhee Jo¹, Waleed Ahmed El-Said^1,2 and Jeong-Woo Choi^1,3,*

¹ Department of Chemical and Biomolecular Engineering, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Korea

² Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt

³ Department of Biomedical Engineering, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Korea

Sensors 2017, 17(12), 2771; https://doi.org/10.3390/s17122771 - 29 Nov 2017

Cited by 75 | Viewed by 9239

Abstract

Several neurological disorders such as Alzheimer’s disease and Parkinson’s disease have become a serious impediment to aging people nowadays. One of the efficient methods used to monitor these neurological disorders is the detection of neurotransmitters such as dopamine. Metal materials, such as gold [...] Read more.

Several neurological disorders such as Alzheimer’s disease and Parkinson’s disease have become a serious impediment to aging people nowadays. One of the efficient methods used to monitor these neurological disorders is the detection of neurotransmitters such as dopamine. Metal materials, such as gold and platinum, are widely used in this electrochemical detection method; however, low sensitivity and linearity at low dopamine concentrations limit the use of these materials. To overcome these limitations, a silver nanoparticle (SNP) modified electrode covered by graphene oxide for the detection of dopamine was newly developed in this study. For the first time, the surface of an indium tin oxide (ITO) electrode was modified using SNPs and graphene oxide sequentially through the electrochemical deposition method. The developed biosensor provided electrochemical signal enhancement at low dopamine concentrations in comparison with previous biosensors. Therefore, our newly developed SNP modified electrode covered by graphene oxide can be used to monitor neurological diseases through electrochemical signal enhancement at low dopamine concentrations. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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25 pages, 3091 KiB

Open AccessArticle

Development of Spectral Disease Indices for ‘Flavescence Dorée’ Grapevine Disease Identification

by Hania AL-Saddik^*

, Jean-Claude Simon and Frederic Cointault

INRA, UMR 1347 Agroecology, 21000 Dijon, France

Sensors 2017, 17(12), 2772; https://doi.org/10.3390/s17122772 - 29 Nov 2017

Cited by 61 | Viewed by 7781

Abstract

Spectral measurements are employed in many precision agriculture applications, due to their ability to monitor the vegetation’s health state. Spectral vegetation indices are one of the main techniques currently used in remote sensing activities, since they are related to biophysical and biochemical crop [...] Read more.

Spectral measurements are employed in many precision agriculture applications, due to their ability to monitor the vegetation’s health state. Spectral vegetation indices are one of the main techniques currently used in remote sensing activities, since they are related to biophysical and biochemical crop variables. Moreover, they have been evaluated in some studies as potentially beneficial for detecting or differentiating crop diseases. Flavescence Dorée (FD) is an infectious, incurable disease of the grapevine that can produce severe yield losses and, hence, compromise the stability of the vineyards. The aim of this study was to develop specific spectral disease indices (SDIs) for the detection of FD disease in grapevines. Spectral signatures of healthy and diseased grapevine leaves were measured with a non-imaging spectro-radiometer at two infection severity levels. The most discriminating wavelengths were selected by a genetic algorithm (GA) feature selection tool, the Spectral Disease Indices (SDIs) are designed by exhaustively testing all possible combinations of wavelengths chosen. The best weighted combination of a single wavelength and a normalized difference is chosen to create the index. The SDIs are tested for their ability to differentiate healthy from diseased vine leaves and they are compared to some common set of Spectral Vegetation Indices (SVIs). It was demonstrated that using vegetation indices was, in general, better than using complete spectral data and that SDIs specifically designed for FD performed better than traditional SVIs in most of cases. The precision of the classification is higher than 90%. This study demonstrates that SDIs have the potential to improve disease detection, identification and monitoring in precision agriculture applications. Full article

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

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12 pages, 5008 KiB

Open AccessArticle

Study of Optical Fiber Sensors for Cryogenic Temperature Measurements

by Veronica De Miguel-Soto^1,*, Daniel Leandro¹, Aitor Lopez-Aldaba¹, Juan Jesus Beato-López², José Ignacio Pérez-Landazábal^2,3, Jean-Louis Auguste⁴, Raphael Jamier⁴, Philippe Roy⁴ and Manuel Lopez-Amo¹

¹ Institute of Smart Cities and Department of Electrical and Electronic Engineering, Campus de Arrosadia S/N, Universidad Pública de Navarra, Pamplona E-31006, Spain

² Department of Physics, Universidad Pública de Navarra, Pamplona 31006, Spain

³ Institute for Advanced Materials (INAMAT), Universidad Pública de Navarra, Pamplona 31006, Spain

⁴ Xlim, Fibre Photonics Department, UMR CNRS/University of Limoges 7252, 87060 Limoges Cedex, France

Sensors 2017, 17(12), 2773; https://doi.org/10.3390/s17122773 - 30 Nov 2017

Cited by 26 | Viewed by 6295

Abstract

In this work, the performance of five different fiber optic sensors at cryogenic temperatures has been analyzed. A photonic crystal fiber Fabry-Pérot interferometer, two Sagnac interferometers, a commercial fiber Bragg grating (FBG), and a π-phase shifted fiber Bragg grating interrogated in a random [...] Read more.

In this work, the performance of five different fiber optic sensors at cryogenic temperatures has been analyzed. A photonic crystal fiber Fabry-Pérot interferometer, two Sagnac interferometers, a commercial fiber Bragg grating (FBG), and a π-phase shifted fiber Bragg grating interrogated in a random distributed feedback fiber laser have been studied. Their sensitivities and resolutions as sensors for cryogenic temperatures have been compared regarding their advantages and disadvantages. Additionally, the results have been compared with the given by a commercial optical backscatter reflectometer that allowed for distributed temperature measurements of a single mode fiber. Full article

(This article belongs to the Section Physical Sensors)

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11 pages, 4328 KiB

Open AccessArticle

Laser Scanning Confocal Thermoreflectance Microscope for the Backside Thermal Imaging of Microelectronic Devices

by Dong Uk Kim, Chan Bae Jeong, Jung Dae Kim, Kye-Sung Lee, Hwan Hur, Ki-Hwan Nam, Geon Hee Kim and Ki Soo Chang^*

Division of Scientific Instrumentation, Korea Basic Science Institute, 169-148 Gwahak-ro, Yuseong-gu, Daejeon 34133, Korea

Sensors 2017, 17(12), 2774; https://doi.org/10.3390/s17122774 - 30 Nov 2017

Cited by 8 | Viewed by 8415

Abstract

In this paper, we report on a confocal thermoreflectance imaging system that can examine the thermal characteristics of microelectronic devices by penetrating the backside of a device through the substrate. In this system, the local reflectivity variations due to heat generation in the [...] Read more.

In this paper, we report on a confocal thermoreflectance imaging system that can examine the thermal characteristics of microelectronic devices by penetrating the backside of a device through the substrate. In this system, the local reflectivity variations due to heat generation in the device are measured point by point by a laser scanning confocal microscope capable of eliminating out-of-focus reflections and the thermoreflectance is extracted via Fourier-domain signal processing. In comparison to the conventional widefield thermoreflectance microscope, the proposed laser scanning confocal thermoreflectance microscope improves the thermoreflectance sensitivity by ~23 times and the spatial resolution by ~25% in backside thermoreflectance measurements. Full article

(This article belongs to the Section Physical Sensors)

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20 pages, 8981 KiB

Open AccessArticle

Modeling of Sensor Placement Strategy for Shape Sensing and Structural Health Monitoring of a Wing-Shaped Sandwich Panel Using Inverse Finite Element Method

by Adnan Kefal^1,2,*

and Mehmet Yildiz^1,2,3

¹ Composite Technologies Center of Excellence, Istanbul Technology Development Zone, Sabanci University-Kordsa Global, Pendik, Istanbul 34906, Turkey

² Integrated Manufacturing Technologies Research and Application Center, Sabanci University, Tuzla, Istanbul 34956, Turkey

³ Faculty of Engineering and Natural Sciences, Sabanci University, Tuzla, Istanbul 34956, Turkey

Sensors 2017, 17(12), 2775; https://doi.org/10.3390/s17122775 - 30 Nov 2017

Cited by 73 | Viewed by 8732

Abstract

This paper investigated the effect of sensor density and alignment for three-dimensional shape sensing of an airplane-wing-shaped thick panel subjected to three different loading conditions, i.e., bending, torsion, and membrane loads. For shape sensing analysis of the panel, the Inverse Finite Element Method [...] Read more.

This paper investigated the effect of sensor density and alignment for three-dimensional shape sensing of an airplane-wing-shaped thick panel subjected to three different loading conditions, i.e., bending, torsion, and membrane loads. For shape sensing analysis of the panel, the Inverse Finite Element Method (iFEM) was used together with the Refined Zigzag Theory (RZT), in order to enable accurate predictions for transverse deflection and through-the-thickness variation of interfacial displacements. In this study, the iFEM-RZT algorithm is implemented by utilizing a novel three-node C°-continuous inverse-shell element, known as i3-RZT. The discrete strain data is generated numerically through performing a high-fidelity finite element analysis on the wing-shaped panel. This numerical strain data represents experimental strain readings obtained from surface patched strain gauges or embedded fiber Bragg grating (FBG) sensors. Three different sensor placement configurations with varying density and alignment of strain data were examined and their corresponding displacement contours were compared with those of reference solutions. The results indicate that a sparse distribution of FBG sensors (uniaxial strain measurements), aligned in only the longitudinal direction, is sufficient for predicting accurate full-field membrane and bending responses (deformed shapes) of the panel, including a true zigzag representation of interfacial displacements. On the other hand, a sparse deployment of strain rosettes (triaxial strain measurements) is essentially enough to produce torsion shapes that are as accurate as those of predicted by a dense sensor placement configuration. Hence, the potential applicability and practical aspects of i3-RZT/iFEM methodology is proven for three-dimensional shape-sensing of future aerospace structures. Full article

(This article belongs to the Special Issue Sensor Technologies for Health Monitoring of Composite Structures)

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11 pages, 1501 KiB

Open AccessArticle

Electrochemical Immunosensor for the Detection of Aflatoxin B₁ in Palm Kernel Cake and Feed Samples

by Farah Asilah Azri¹, Jinap Selamat^1,2,*

and Rashidah Sukor^1,2

¹ Food Safety and Food Integrity (FOSFI), Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia

² Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia

Sensors 2017, 17(12), 2776; https://doi.org/10.3390/s17122776 - 30 Nov 2017

Cited by 31 | Viewed by 5855

Abstract

Palm kernel cake (PKC) is the solid residue following oil extraction of palm kernels and useful to fatten animals either as a single feed with only minerals and vitamins supplementation, or mixed with other feedstuffs such as corn kernels or soy beans. The [...] Read more.

Palm kernel cake (PKC) is the solid residue following oil extraction of palm kernels and useful to fatten animals either as a single feed with only minerals and vitamins supplementation, or mixed with other feedstuffs such as corn kernels or soy beans. The occurrence of mycotoxins (aflatoxins, ochratoxins, zearalenone, and fumonisins) in feed samples affects the animal’s health and also serves as a secondary contamination to humans via consumption of eggs, milk and meats. Of these, aflatoxin B₁ (AFB₁) is the most toxically potent and a confirmed carcinogen to both humans and animals. Methods such as High Performance Liquid Chromatography (HPLC) and Liquid Chromatography–Mass Spectrometry (LC-MS/MS) are common in the determination of mycotoxins. However, these methods usually require sample pre-treatment, extensive cleanup and skilled operator. Therefore, in the present work, a rapid method of electrochemical immunosensor for the detection of AFB₁ was developed based on an indirect competitive enzyme-linked immunosorbent assay (ELISA). Multi-walled carbon nanotubes (MWCNT) and chitosan (CS) were used as the electrode modifier for signal enhancement. N-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) activated the carboxyl groups at the surface of nanocomposite for the attachment of AFB₁-BSA antigen by covalent bonding. An indirect competitive reaction occurred between AFB₁-BSA and free AFB₁ for the binding site of a fixed amount of anti-AFB₁ antibody. A catalytic signal based on horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H₂O₂) and 3,3′,5,5′-tetramethylbenzidine (TMB) mediator was observed as a result of attachment of the secondary antibody to the immunoassay system. As a result, the reduction peak of TMB_(Ox) was measured by using differential pulse voltammetry (DPV) analysis. Based on the results, the electrochemical surface area was increased from 0.396 cm² to 1.298 cm² due to the electrode modification with MWCNT/CS. At the optimal conditions, the working range of the electrochemical immunosensor was from 0.0001 to 10 ng/mL with limit of detection of 0.1 pg/mL. Good recoveries were obtained for the detection of spiked feed samples (PKC, corn kernels, soy beans). The developed method could be used for the screening of AFB₁ in real samples. Full article

(This article belongs to the Section Biosensors)

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14 pages, 5250 KiB

Open AccessArticle

A Sensitive and Stable Surface Plasmon Resonance Sensor Based on Monolayer Protected Silver Film

by Guiqiang Wang^1,2, Chunnan Wang^1,2, Rui Yang¹, Wenlan Liu³ and Shuqing Sun^1,2,*

¹ Shenzhen Key Laboratory for Minimal Invasive Medical Technologies, Institute of Optical Imaging and Sensing, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China

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

³ The Central Laboratory, The First Affiliated Hospital of Shenzhen University, Shenzhen Second People’s Hospital, Shenzhen 518035, China

Sensors 2017, 17(12), 2777; https://doi.org/10.3390/s17122777 - 30 Nov 2017

Cited by 77 | Viewed by 6682

Abstract

In this paper, we present a stable silver-based surface plasmon resonance (SPR) sensor using a self-assembled monolayer (SAM) as a protection layer and investigated its efficiency in water and 0.01 M phosphate buffered saline (PBS). By simulation, silver-based SPR sensor has a better [...] Read more.

In this paper, we present a stable silver-based surface plasmon resonance (SPR) sensor using a self-assembled monolayer (SAM) as a protection layer and investigated its efficiency in water and 0.01 M phosphate buffered saline (PBS). By simulation, silver-based SPR sensor has a better performance in field enhancement and penetration depth than that of a gold-based SPR sensor, which are 5 and 1.4 times, respectively. To overcome the instability of the bare silver film and investigate the efficiency of the protected layer, the SAM of 11-mercapto-1-undecanol (MUD) was used as a protection layer. Stability experiment results show that the protected silver film exhibited excellent stability either in pure water or 0.01 M PBS buffer. The sensitivity of the silver-based SPR sensor was calculated to be 127.26 deg/RIU (refractive index unit), measured with different concentrations of NaCl solutions. Further, a very high refractive resolution for the silver-based SPR sensor was found to be 2.207 × 10⁻⁷ RIU, which reaches the theoretical limit in the wavelength of 632.8 nm for a SPR sensor reported in the literature. Using a mixed SAM of 16-mercaptohexadecanoic acid (MHDA) and a MUD layer with a ratio of 1:10, this immunosensor for the rabbit immunoglobulin G (IgG) molecule with a limit of detection as low as 22.516 ng/mL was achieved. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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19 pages, 5992 KiB

Open AccessArticle

A Denoising Method for Randomly Clustered Noise in ICCD Sensing Images Based on Hypergraph Cut and Down Sampling

by Meng Yang, Fei Wang^*, Yibin Wang and Nanning Zheng

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

Sensors 2017, 17(12), 2778; https://doi.org/10.3390/s17122778 - 30 Nov 2017

Cited by 8 | Viewed by 4622

Abstract

Intensified charge-coupled device (ICCD) images are captured by ICCD sensors in extremely low-light conditions. They often contains spatially clustered noises and general filtering methods do not work well. We find that the scale of the clustered noise in ICCD sensing images is often [...] Read more.

Intensified charge-coupled device (ICCD) images are captured by ICCD sensors in extremely low-light conditions. They often contains spatially clustered noises and general filtering methods do not work well. We find that the scale of the clustered noise in ICCD sensing images is often much smaller than that of the true structural information. Then the clustered noise can be identified by properly down-sampling and then up-sampling the ICCD sensing image and comparing it to the noisy image. Based on this finding, we present a denoising algorithm to remove the randomly clustered noise in ICCD images. First, we over-segment the ICCD image into a set of flat patches, and each patch contains very little structural information. Second, we classify the patches into noisy patches and noise-free patches based on the hypergraph cut method. Then the noise-free patches are easily recovered by the general block-matching and 3D filtering (BM3D) algorithm, since they often do not contain the clustered noise. The noisy patches are recovered by subtracting the identified clustered noise from the noisy patches. After that, we could get the whole recovered ICCD image. Finally, the quality of the recovered ICCD image is further improved by diminishing the remaining sparse noise with robust principal component analysis. Experiments are conducted on a set of ICCD images and compared with four existing denoising algorithms, which shows that the proposed algorithm removes well the randomly clustered noise and preserves the true textural information in the ICCD sensing images. Full article

(This article belongs to the Special Issue Charge-Coupled Device (CCD) Sensors)

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15 pages, 2538 KiB

Open AccessArticle

Using Spherical-Harmonics Expansions for Optics Surface Reconstruction from Gradients

by Juan Manuel Solano-Altamirano^1,*, Alejandro Vázquez-Otero^2,*, Danila Khikhlukha^3,*, Raquel Dormido⁴

and Natividad Duro⁴

¹ Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, 14 Sur y Av. San Claudio, Col. San Manuel, Puebla 72520, Mexico

² MSD IT Global Innovation Center s.r.o., Svornosti 3321/2, 150 00 Prague 5, Czech Republic

³ ELI Beamlines, Institute of Physics ASCR, Za Radnicí 835, 252 41 Dolní Břežany, Czech Republic

⁴ Department of Computer Sciences and Automatic Control, UNED, C/Juan del Rosal, 16, 28040 Madrid, Spain

Sensors 2017, 17(12), 2780; https://doi.org/10.3390/s17122780 - 30 Nov 2017

Cited by 3 | Viewed by 5470

Abstract

In this paper, we propose a new algorithm to reconstruct optics surfaces (aka wavefronts) from gradients, defined on a circular domain, by means of the Spherical Harmonics. The experimental results indicate that this algorithm renders the same accuracy, compared to the reconstruction based [...] Read more.

In this paper, we propose a new algorithm to reconstruct optics surfaces (aka wavefronts) from gradients, defined on a circular domain, by means of the Spherical Harmonics. The experimental results indicate that this algorithm renders the same accuracy, compared to the reconstruction based on classical Zernike polynomials, using a smaller number of polynomial terms, which potentially speeds up the wavefront reconstruction. Additionally, we provide an open-source C++ library, released under the terms of the GNU General Public License version 2 (GPLv2), wherein several polynomial sets are coded. Therefore, this library constitutes a robust software alternative for wavefront reconstruction in a high energy laser field, optical surface reconstruction, and, more generally, in surface reconstruction from gradients. The library is a candidate for being integrated in control systems for optical devices, or similarly to be used in ad hoc simulations. Moreover, it has been developed with flexibility in mind, and, as such, the implementation includes the following features: (i) a mock-up generator of various incident wavefronts, intended to simulate the wavefronts commonly encountered in the field of high-energy lasers production; (ii) runtime selection of the library in charge of performing the algebraic computations; (iii) a profiling mechanism to measure and compare the performance of different steps of the algorithms and/or third-party linear algebra libraries. Finally, the library can be easily extended to include additional dependencies, such as porting the algebraic operations to specific architectures, in order to exploit hardware acceleration features. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 4260 KiB

Open AccessArticle

Proton Radiation Effects on Dark Signal Distribution of PPD CMOS Image Sensors: Both TID and DDD Effects

by Yuanyuan Xue, Zujun Wang^*, Wei Chen^*, Minbo Liu, Baoping He, Zhibin Yao, Jiangkun Sheng, Wuying Ma, Guantao Dong and Junshan Jin

State Key Laboratory of Intense Pulsed Irradiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi’an 710024, China

Sensors 2017, 17(12), 2781; https://doi.org/10.3390/s17122781 - 30 Nov 2017

Cited by 7 | Viewed by 5466

Abstract

Four-transistor (T) pinned photodiode (PPD) CMOS image sensors (CISs) with four-megapixel resolution using 11µm pitch high dynamic range pixel were radiated with 3 MeV and 10MeV protons. The dark signal was measured pre- and post-radiation, with the dark signal post irradiation showing a [...] Read more.

Four-transistor (T) pinned photodiode (PPD) CMOS image sensors (CISs) with four-megapixel resolution using 11µm pitch high dynamic range pixel were radiated with 3 MeV and 10MeV protons. The dark signal was measured pre- and post-radiation, with the dark signal post irradiation showing a remarkable increase. A theoretical method of dark signal distribution pre- and post-radiation is used to analyze the degradation mechanisms of the dark signal distribution. The theoretical results are in good agreement with experimental results. This research would provide a good understanding of the proton radiation effects on the CIS and make it possible to predict the dark signal distribution of the CIS under the complex proton radiation environments. Full article

(This article belongs to the Special Issue Image Sensors)

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14 pages, 19108 KiB

Open AccessArticle

Efficient Background Segmentation and Seed Point Generation for a Single-Shot Stereo System

by Xiao Yang^1,2

, Xiaobo Chen^1,2 and Juntong Xi^1,2,3,*

¹ School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

² Shanghai Key Laboratory of Advanced Manufacturing Environment, Shanghai 200030, China

³ State Key Laboratory of Mechanical System and Vibration, Shanghai 200240, China

Sensors 2017, 17(12), 2782; https://doi.org/10.3390/s17122782 - 1 Dec 2017

Cited by 8 | Viewed by 4302

Abstract

Single-shot stereo 3D shape measurement is becoming more popular due to its advantages of noise robustness and short acquisition period. One of the key problems is stereo matching, which is related to the efficiency of background segmentation and seed point generation, etc. In [...] Read more.

Single-shot stereo 3D shape measurement is becoming more popular due to its advantages of noise robustness and short acquisition period. One of the key problems is stereo matching, which is related to the efficiency of background segmentation and seed point generation, etc. In this paper, a more efficient and automated matching algorithm based on digital image correlation (DIC) is proposed. The standard deviation of image gradients and an adaptive threshold are employed to segment the background. Scale-invariant feature transform (SIFT)-based feature matching and two-dimensional triangulation are combined to estimate accurate initial parameters for seed point generation. The efficiency of background segmentation and seed point generation, as well as the measuring precision, are evaluated by experimental simulation and real tests. Experimental results show that the average segmentation time for an image with a resolution of 1280 × 960 pixels is 240 milliseconds. The efficiency of seed point generation is verified to be high with different convergence criteria. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 7838 KiB

Open AccessArticle

A Pseudorange Measurement Scheme Based on Snapshot for Base Station Positioning Receivers

by Jun Mo^*

, Zhongliang Deng, Buyun Jia and Xinmei Bian

School of Electronic Engineering, Beijing University of Posts and Telecommunications, No. 10 Xitucheng Road, Haidian District, Beijing 100876, China

Sensors 2017, 17(12), 2783; https://doi.org/10.3390/s17122783 - 1 Dec 2017

Cited by 8 | Viewed by 4622

Abstract

Digital multimedia broadcasting signal is promised to be a wireless positioning signal. This paper mainly studies a multimedia broadcasting technology, named China mobile multimedia broadcasting (CMMB), in the context of positioning. Theoretical and practical analysis on the CMMB signal suggests that the existing [...] Read more.

Digital multimedia broadcasting signal is promised to be a wireless positioning signal. This paper mainly studies a multimedia broadcasting technology, named China mobile multimedia broadcasting (CMMB), in the context of positioning. Theoretical and practical analysis on the CMMB signal suggests that the existing CMMB signal does not have the meter positioning capability. So, the CMMB system has been modified to achieve meter positioning capability by multiplexing the CMMB signal and pseudo codes in the same frequency band. The time difference of arrival (TDOA) estimation method is used in base station positioning receivers. Due to the influence of a complex fading channel and the limited bandwidth of receivers, the regular tracking method based on pseudo code ranging is difficult to provide continuous and accurate TDOA estimations. A pseudorange measurement scheme based on snapshot is proposed to solve the problem. This algorithm extracts the TDOA estimation from the stored signal fragments, and utilizes the Taylor expansion of the autocorrelation function to improve the TDOA estimation accuracy. Monte Carlo simulations and real data tests show that the proposed algorithm can significantly reduce the TDOA estimation error for base station positioning receivers, and then the modified CMMB system achieves meter positioning accuracy. Full article

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

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6 pages, 1031 KiB

Open AccessArticle

A Direct Bicarbonate Detection Method Based on a Near-Concentric Cavity-Enhanced Raman Spectroscopy System

by Dewang Yang, Jinjia Guo^*, Chunhao Liu, Qingsheng Liu and Ronger Zheng

College of Information Science & Engineering, Ocean University of China, Qingdao 266000, China

Sensors 2017, 17(12), 2784; https://doi.org/10.3390/s17122784 - 1 Dec 2017

Cited by 7 | Viewed by 5720

Abstract

Raman spectroscopy has great potential as a tool in a variety of hydrothermal science applications. However, its low sensitivity has limited its use in common sea areas. In this paper, we develop a near-concentric cavity-enhanced Raman spectroscopy system to directly detect bicarbonate in [...] Read more.

Raman spectroscopy has great potential as a tool in a variety of hydrothermal science applications. However, its low sensitivity has limited its use in common sea areas. In this paper, we develop a near-concentric cavity-enhanced Raman spectroscopy system to directly detect bicarbonate in seawater for the first time. With the aid of this near-concentric cavity-enhanced Raman spectroscopy system, a significant enhancement in HCO₃⁻ detection has been achieved. The obtained limit of detection (LOD) is determined to be 0.37 mmol/L—much lower than the typical concentration of HCO₃⁻ in seawater. By introducing a specially developed data processing scheme, the weak HCO₃⁻ signal is extracted from the strong sulfate signal background, hence a quantitative analysis with R² of 0.951 is made possible. Based on the spectra taken from deep sea seawater sampling, the concentration of HCO₃⁻ has been determined to be 1.91 mmol/L, with a relative error of 2.1% from the reported value (1.95 mmol/L) of seawater in the ocean. It is expected that the near-concentric cavity-enhanced Raman spectroscopy system could be developed and used for in-situ ocean observation in the near future. Full article

(This article belongs to the Special Issue Smart Sensing System for Real-Time Monitoring)

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11 pages, 7788 KiB

Open AccessArticle

Assessment of GF-3 Polarimetric SAR Data for Physical Scattering Mechanism Analysis and Terrain Classification

by Junjun Yin¹

, Jian Yang² and Qingjun Zhang^3,*

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

² Department of Electronic Engineering, Tsinghua University, Beijing 100084, China

³ Beijing Institute of Space System Engineering, China Academy of Space Technology, Beijing 100086, China

Sensors 2017, 17(12), 2785; https://doi.org/10.3390/s17122785 - 1 Dec 2017

Cited by 18 | Viewed by 5261

Abstract

On 10 August 2016 China launched the GF-3, its first C-band polarimetric synthetic aperture radar (SAR) satellite, which was put into operation at the end of January, 2017. GF-3 polarimetric SAR has many advantages such as high resolution and multi-polarization imaging capabilities. Polarimetric [...] Read more.

On 10 August 2016 China launched the GF-3, its first C-band polarimetric synthetic aperture radar (SAR) satellite, which was put into operation at the end of January, 2017. GF-3 polarimetric SAR has many advantages such as high resolution and multi-polarization imaging capabilities. Polarimetric SAR can fully characterize the backscatter property of targets, and thus it is of great interest to explore the physical scattering mechanisms of terrain types, which is very important in interpreting polarimetric SAR imagery and for its further usages in Earth observations. In this paper, focusing on target scattering characterization and feature extraction, we generalize the

Δ α_{B} / α_{B}

method, which was proposed under the reflection symmetric assumption, for the general backscatter process to account for both the reflection symmetry and asymmetry cases. Then, we evaluate the performances of physical scattering mechanism analysis methods for GF-3 polarimetric SAR imagery. Radarsat-2 data acquired over the same area is used for cross validation. Results show that GF-3 polarimetric SAR data has great potential for target characterization, especially for ocean area observation. Full article

(This article belongs to the Special Issue First Experiences with Chinese Gaofen-3 SAR Sensor)

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9 pages, 2745 KiB

Open AccessArticle

Marked Object Recognition Multitouch Screen Printed Touchpad for Interactive Applications

by Jivago Serrado Nunes^1,2,†, Nelson Castro^3,†, Sergio Gonçalves^1,2,4

, Nélson Pereira^1,2

, Vitor Correia^1,2 and Senentxu Lanceros-Mendez^1,3,5,*

¹ Center of Physics, University of Minho, 4710-057 Braga, Portugal

² Centro ALGORITMI, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal

³ Basque Center for Materials, Applications and Nanostructures (BCMaterials), 48160 Derio, Spain

⁴ engageLab, University of Minho, 4810-453 Guimarães, Portugal

⁵ Ikerbasque, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2786; https://doi.org/10.3390/s17122786 - 1 Dec 2017

Cited by 9 | Viewed by 5696

Abstract

The market for interactive platforms is rapidly growing, and touchscreens have been incorporated in an increasing number of devices. Thus, the area of smart objects and devices is strongly increasing by adding interactive touch and multimedia content, leading to new uses and capabilities. [...] Read more.

The market for interactive platforms is rapidly growing, and touchscreens have been incorporated in an increasing number of devices. Thus, the area of smart objects and devices is strongly increasing by adding interactive touch and multimedia content, leading to new uses and capabilities. In this work, a flexible screen printed sensor matrix is fabricated based on silver ink in a polyethylene terephthalate (PET) substrate. Diamond shaped capacitive electrodes coupled with conventional capacitive reading electronics enables fabrication of a highly functional capacitive touchpad, and also allows for the identification of marked objects. For the latter, the capacitive signatures are identified by intersecting points and distances between them. Thus, this work demonstrates the applicability of a low cost method using royalty-free geometries and technologies for the development of flexible multitouch touchpads for the implementation of interactive and object recognition applications. Full article

(This article belongs to the Special Issue Tactile Sensors and Sensing)

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21 pages, 1214 KiB

Open AccessArticle

Adaptive Residual Interpolation for Color and Multispectral Image Demosaicking

by Yusuke Monno^1,*

, Daisuke Kiku^1,‡, Masayuki Tanaka^1,2 and Masatoshi Okutomi¹

¹ Department of Systems and Control Engineering, School of Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8550, Japan

² Artificial Intelligence Research Center, National Institute of Advanced Industrial Science and Technology, Koto-ku, Tokyo 135-0064, Japan

^‡ Current affiliation is Olympus Corporation, Hachioji, Tokyo 192-8512, Japan. This work was performed in part when the author was a graduate student at Tokyo Institute of Technology.

Sensors 2017, 17(12), 2787; https://doi.org/10.3390/s17122787 - 1 Dec 2017

Cited by 80 | Viewed by 11933

Abstract

Color image demosaicking for the Bayer color filter array is an essential image processing operation for acquiring high-quality color images. Recently, residual interpolation (RI)-based algorithms have demonstrated superior demosaicking performance over conventional color difference interpolation-based algorithms. In this paper, we propose adaptive residual [...] Read more.

Color image demosaicking for the Bayer color filter array is an essential image processing operation for acquiring high-quality color images. Recently, residual interpolation (RI)-based algorithms have demonstrated superior demosaicking performance over conventional color difference interpolation-based algorithms. In this paper, we propose adaptive residual interpolation (ARI) that improves existing RI-based algorithms by adaptively combining two RI-based algorithms and selecting a suitable iteration number at each pixel. These are performed based on a unified criterion that evaluates the validity of an RI-based algorithm. Experimental comparisons using standard color image datasets demonstrate that ARI can improve existing RI-based algorithms by more than 0.6 dB in the color peak signal-to-noise ratio and can outperform state-of-the-art algorithms based on training images. We further extend ARI for a multispectral filter array, in which more than three spectral bands are arrayed, and demonstrate that ARI can achieve state-of-the-art performance also for the task of multispectral image demosaicking. Full article

(This article belongs to the Special Issue Snapshot Multi-Band Spectral and Polarization Imaging Systems)

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16 pages, 896 KiB

Open AccessArticle

PCA Based Stress Monitoring of Cylindrical Specimens Using PZTs and Guided Waves

by Jabid Quiroga^1,*

, Luis Mujica², Rodolfo Villamizar¹

, Magda Ruiz² and Jhonatan Camacho²

¹ Schools of Mechanical and Electric, Electronics and Telecommunications Engineering, Universidad Industrial de Santander (UIS), Cra 27 Calle 9, 680002 Bucaramanga, Colombia

² Departament de Matemàtiques, CoDAlab, Escola d’Enginyeria de Barcelona Est (EEBE), Universitat Politècnica de Catalunya, Campus Diagonal-Besòs. C, Eduard Maristany, 6-12, St. Adrià de Besòs, 08930 Barcelona, Spain

Sensors 2017, 17(12), 2788; https://doi.org/10.3390/s17122788 - 1 Dec 2017

Cited by 18 | Viewed by 4744

Abstract

Since mechanical stress in structures affects issues such as strength, expected operational life and dimensional stability, a continuous stress monitoring scheme is necessary for a complete integrity assessment. Consequently, this paper proposes a stress monitoring scheme for cylindrical specimens, which are widely used [...] Read more.

Since mechanical stress in structures affects issues such as strength, expected operational life and dimensional stability, a continuous stress monitoring scheme is necessary for a complete integrity assessment. Consequently, this paper proposes a stress monitoring scheme for cylindrical specimens, which are widely used in structures such as pipelines, wind turbines or bridges. The approach consists of tracking guided wave variations due to load changes, by comparing wave statistical patterns via Principal Component Analysis (PCA). Each load scenario is projected to the PCA space by means of a baseline model and represented using the Q-statistical indices. Experimental validation of the proposed methodology is conducted on two specimens: (i) a 12.7 mm (

1 / 2 ″

) diameter, 0.4 m length, AISI 1020 steel rod, and (ii) a 25.4 mm (

1 ″

) diameter, 6m length, schedule 40, A-106, hollow cylinder. Specimen 1 was subjected to axial loads, meanwhile specimen 2 to flexion. In both cases, simultaneous longitudinal and flexural guided waves were generated via piezoelectric devices (PZTs) in a pitch-catch configuration. Experimental results show the feasibility of the approach and its potential use as in-situ continuous stress monitoring application. Full article

(This article belongs to the Special Issue Piezoelectric Micro- and Nano-Devices)

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17 pages, 5957 KiB

Open AccessArticle

Synthesis and Characterization of Polyaniline/Graphene Composite Nanofiber and Its Application as an Electrochemical DNA Biosensor for the Detection of Mycobacterium tuberculosis

by Fatimah Syahidah Mohamad, Mohd Hazani Mat Zaid

, Jaafar Abdullah

, Ruzniza Mohd Zawawi, Hong Ngee Lim

, Yusran Sulaiman

and Norizah Abdul Rahman^*

Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Malaysia

Sensors 2017, 17(12), 2789; https://doi.org/10.3390/s17122789 - 2 Dec 2017

Cited by 51 | Viewed by 6689

Abstract

This article describes chemically modified polyaniline and graphene (PANI/GP) composite nanofibers prepared by self-assembly process using oxidative polymerization of aniline monomer and graphene in the presence of a solution containing poly(methyl vinyl ether-alt-maleic acid) (PMVEA). Characterization of the composite nanofibers was [...] Read more.

This article describes chemically modified polyaniline and graphene (PANI/GP) composite nanofibers prepared by self-assembly process using oxidative polymerization of aniline monomer and graphene in the presence of a solution containing poly(methyl vinyl ether-alt-maleic acid) (PMVEA). Characterization of the composite nanofibers was carried out by Fourier transform infrared (FTIR) and Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). SEM images revealed the size of the PANI nanofibers ranged from 90 to 360 nm in diameter and was greatly influenced by the proportion of PMVEA and graphene. The composite nanofibers with an immobilized DNA probe were used for the detection of Mycobacterium tuberculosis by using an electrochemical technique. A photochemical indicator, methylene blue (MB) was used to monitor the hybridization of target DNA by using differential pulse voltammetry (DPV) method. The detection range of DNA biosensor was obtained from of 10⁻⁶–10⁻⁹ M with the detection limit of 7.853 × 10⁻⁷ M under optimum conditions. The results show that the composite nanofibers have a great potential in a range of applications for DNA sensors. Full article

(This article belongs to the Section Biosensors)

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29 pages, 10338 KiB

Open AccessArticle

A Wideband Magnetoresistive Sensor for Monitoring Dynamic Fault Slip in Laboratory Fault Friction Experiments

by Brian D. Kilgore

U.S. Geological Survey, 345 Middlefield Rd. MS-977, Menlo Park, CA 94025, USA

Sensors 2017, 17(12), 2790; https://doi.org/10.3390/s17122790 - 2 Dec 2017

Viewed by 6627

Abstract

A non-contact, wideband method of sensing dynamic fault slip in laboratory geophysical experiments employs an inexpensive magnetoresistive sensor, a small neodymium rare earth magnet, and user built application-specific wideband signal conditioning. The magnetoresistive sensor generates a voltage proportional to the changing angles of [...] Read more.

A non-contact, wideband method of sensing dynamic fault slip in laboratory geophysical experiments employs an inexpensive magnetoresistive sensor, a small neodymium rare earth magnet, and user built application-specific wideband signal conditioning. The magnetoresistive sensor generates a voltage proportional to the changing angles of magnetic flux lines, generated by differential motion or rotation of the near-by magnet, through the sensor. The performance of an array of these sensors compares favorably to other conventional position sensing methods employed at multiple locations along a 2 m long × 0.4 m deep laboratory strike-slip fault. For these magnetoresistive sensors, the lack of resonance signals commonly encountered with cantilever-type position sensor mounting, the wide band response (DC to ≈ 100 kHz) that exceeds the capabilities of many traditional position sensors, and the small space required on the sample, make them attractive options for capturing high speed fault slip measurements in these laboratory experiments. An unanticipated observation of this study is the apparent sensitivity of this sensor to high frequency electomagnetic signals associated with fault rupture and (or) rupture propagation, which may offer new insights into the physics of earthquake faulting. Full article

(This article belongs to the Special Issue GMR and TMR Sensors)

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13 pages, 2993 KiB

Open AccessArticle

Vertical Optical Scanning with Panoramic Vision for Tree Trunk Reconstruction

by Adilson Berveglieri^1,*, Antonio M. G. Tommaselli¹

, Xinlian Liang^2,3 and Eija Honkavaara²

¹ Department of Cartography, São Paulo State University UNESP, 305, Presidente Prudente 19060-900, Brazil

² Department of Remote Sensing and Photogrammetry, Finnish Geodetic Institute FGI, National Land Survey of Finland, 00521 Helsinki, Finland

³ Centre of Excellence in Laser Scanning Research, Academy of Finland, 02430 Helsinki, Finland

Sensors 2017, 17(12), 2791; https://doi.org/10.3390/s17122791 - 2 Dec 2017

Cited by 10 | Viewed by 6299

Abstract

This paper presents a practical application of a technique that uses a vertical optical flow with a fisheye camera to generate dense point clouds from a single planimetric station. Accurate data can be extracted to enable the measurement of tree trunks or branches. [...] Read more.

This paper presents a practical application of a technique that uses a vertical optical flow with a fisheye camera to generate dense point clouds from a single planimetric station. Accurate data can be extracted to enable the measurement of tree trunks or branches. The images that are collected with this technique can be oriented in photogrammetric software (using fisheye models) and used to generate dense point clouds, provided that some constraints on the camera positions are adopted. A set of images was captured in a forest plot in the experiments. Weighted geometric constraints were imposed in the photogrammetric software to calculate the image orientation, perform dense image matching, and accurately generate a 3D point cloud. The tree trunks in the scenes were reconstructed and mapped in a local reference system. The accuracy assessment was based on differences between measured and estimated trunk diameters at different heights. Trunk sections from an image-based point cloud were also compared to the corresponding sections that were extracted from a dense terrestrial laser scanning (TLS) point cloud. Cylindrical fitting of the trunk sections allowed the assessment of the accuracies of the trunk geometric shapes in both clouds. The average difference between the cylinders that were fitted to the photogrammetric cloud and those to the TLS cloud was less than 1 cm, which indicates the potential of the proposed technique. The point densities that were obtained with vertical optical scanning were 1/3 less than those that were obtained with TLS. However, the point density can be improved by using higher resolution cameras. Full article

(This article belongs to the Special Issue Terrestrial Laser Scanning)

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12 pages, 4596 KiB

Open AccessArticle

Repetitively Mode-Locked Cavity-Enhanced Absorption Spectroscopy (RML-CEAS) for Near-Infrared Gas Sensing

by Qixin He^1,2

, Minhan Lou¹

, Chuantao Zheng^1,2,*, Weilin Ye^1,3

, Yiding Wang² and Frank K. Tittel¹

¹ Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA

² State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China

³ College of Engineering, Shantou University, 243 Daxue Road, Shantou 515063, China

Sensors 2017, 17(12), 2792; https://doi.org/10.3390/s17122792 - 2 Dec 2017

Cited by 10 | Viewed by 6087

Abstract

A Pound-Drever-Hall (PDH)-based mode-locked cavity-enhanced sensor system was developed using a distributed feedback diode laser centered at 1.53 µm as the laser source. Laser temperature scanning, bias control of the piezoelectric ceramic transducer (PZT) and proportional-integral-derivative (PID) feedback control of diode laser current [...] Read more.

A Pound-Drever-Hall (PDH)-based mode-locked cavity-enhanced sensor system was developed using a distributed feedback diode laser centered at 1.53 µm as the laser source. Laser temperature scanning, bias control of the piezoelectric ceramic transducer (PZT) and proportional-integral-derivative (PID) feedback control of diode laser current were used to repetitively lock the laser modes to the cavity modes. A gas absorption spectrum was obtained by using a series of absorption data from the discrete mode-locked points. The 15 cm-long Fabry-Perot cavity was sealed using an enclosure with an inlet and outlet for gas pumping and a PZT for cavity length tuning. The performance of the sensor system was evaluated by conducting water vapor measurements. A linear relationship was observed between the measured absorption signal amplitude and the H₂O concentration. A minimum detectable absorption coefficient of 1.5 × 10^–8 cm^–1 was achieved with an averaging time of 700 s. This technique can also be used for the detection of other trace gas species by targeting the corresponding gas absorption line. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 505 KiB

Open AccessArticle

A Round-Efficient Authenticated Key Agreement Scheme Based on Extended Chaotic Maps for Group Cloud Meeting

by Tsung-Hung Lin¹

, Chen-Kun Tsung^1,*

, Tian-Fu Lee² and Zeng-Bo Wang¹

¹ Department of Computer Science and Information Engineering, National Chin-Yi University of Technology, No.57, Sec. 2, Zhongshan Rd., Taiping District, Taichung 41170, Taiwan

² Department of Medical Informatics, Tzu Chi University, No.701, Sec. 3, Zhongyang Rd., Hualien 97004, Taiwan

Sensors 2017, 17(12), 2793; https://doi.org/10.3390/s17122793 - 3 Dec 2017

Cited by 3 | Viewed by 4275

Abstract

The security is a critical issue for business purposes. For example, the cloud meeting must consider strong security to maintain the communication privacy. Considering the scenario with cloud meeting, we apply extended chaotic map to present passwordless group authentication key agreement, termed as [...] Read more.

The security is a critical issue for business purposes. For example, the cloud meeting must consider strong security to maintain the communication privacy. Considering the scenario with cloud meeting, we apply extended chaotic map to present passwordless group authentication key agreement, termed as Passwordless Group Authentication Key Agreement (PL-GAKA). PL-GAKA improves the computation efficiency for the simple group password-based authenticated key agreement (SGPAKE) proposed by Lee et al. in terms of computing the session key. Since the extended chaotic map has equivalent security level to the Diffie–Hellman key exchange scheme applied by SGPAKE, the security of PL-GAKA is not sacrificed when improving the computation efficiency. Moreover, PL-GAKA is a passwordless scheme, so the password maintenance is not necessary. Short-term authentication is considered, hence the communication security is stronger than other protocols by dynamically generating session key in each cloud meeting. In our analysis, we first prove that each meeting member can get the correct information during the meeting. We analyze common security issues for the proposed PL-GAKA in terms of session key security, mutual authentication, perfect forward security, and data integrity. Moreover, we also demonstrate that communicating in PL-GAKA is secure when suffering replay attacks, impersonation attacks, privileged insider attacks, and stolen-verifier attacks. Eventually, an overall comparison is given to show the performance between PL-GAKA, SGPAKE and related solutions. Full article

(This article belongs to the Special Issue Selected Papers from IEEE ICICE 2017)

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20 pages, 5223 KiB

Open AccessArticle

A Combined Approach of Sensor Data Fusion and Multivariate Geostatistics for Delineation of Homogeneous Zones in an Agricultural Field

by Annamaria Castrignanò^1,2, Gabriele Buttafuoco^2,*

, Ruggiero Quarto³, Carolina Vitti¹, Giuliano Langella⁴

, Fabio Terribile⁴ and Accursio Venezia⁵

¹ CREA Research Centre for Agriculture and Environment, 70125 Bari, Italy

² National Research Council of Italy, Institute for Agricultural and Forest Systems in the Mediterranean, 87036 Rende (CS), Italy

³ Earth and Geoenvironmental Sciences Department, University of Bari Aldo Moro, 700125 Bari, Italy

⁴ Department of Agriculture, University of Naples Federico II, 8055 Portici (NA), Italy

⁵ CREA Research Center for Vegetable and Ornamental Crops, 84098 Pontecagnano (SA), Italy

Sensors 2017, 17(12), 2794; https://doi.org/10.3390/s17122794 - 3 Dec 2017

Cited by 59 | Viewed by 6418

Abstract

To assess spatial variability at the very fine scale required by Precision Agriculture, different proximal and remote sensors have been used. They provide large amounts and different types of data which need to be combined. An integrated approach, using multivariate geostatistical data-fusion techniques [...] Read more.

To assess spatial variability at the very fine scale required by Precision Agriculture, different proximal and remote sensors have been used. They provide large amounts and different types of data which need to be combined. An integrated approach, using multivariate geostatistical data-fusion techniques and multi-source geophysical sensor data to determine simple summary scale-dependent indices, is described here. These indices can be used to delineate management zones to be submitted to differential management. Such a data fusion approach with geophysical sensors was applied in a soil of an agronomic field cropped with tomato. The synthetic regionalized factors determined, contributed to split the 3D edaphic environment into two main horizontal structures with different hydraulic properties and to disclose two main horizons in the 0–1.0-m depth with a discontinuity probably occurring between 0.40 m and 0.70 m. Comparing this partition with the soil properties measured with a shallow sampling, it was possible to verify the coherence in the topsoil between the dielectric properties and other properties more directly related to agronomic management. These results confirm the advantages of using proximal sensing as a preliminary step in the application of site-specific management. Combining disparate spatial data (data fusion) is not at all a naive problem and novel and powerful methods need to be developed. Full article

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

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24 pages, 14406 KiB

Open AccessArticle

A Robust Indoor/Outdoor Navigation Filter Fusing Data from Vision and Magneto-Inertial Measurement Unit

by David Caruso^1,*, Alexandre Eudes², Martial Sanfourche², David Vissière¹ and Guy Le Besnerais²

¹ Computer Vision R and D department, Sysnav, 57 rue de Montigny, 27200 Vernon, France

² Department of Information Processing and Systems, ONERA, the French Aerospace Lab, Chemin de la Hunière, 91120 Palaiseau, France

Sensors 2017, 17(12), 2795; https://doi.org/10.3390/s17122795 - 4 Dec 2017

Cited by 19 | Viewed by 5511

Abstract

Visual-inertial Navigation Systems (VINS) are nowadays used for robotic or augmented reality applications. They aim to compute the motion of the robot or the pedestrian in an environment that is unknown and does not have specific localization infrastructure. Because of the low quality [...] Read more.

Visual-inertial Navigation Systems (VINS) are nowadays used for robotic or augmented reality applications. They aim to compute the motion of the robot or the pedestrian in an environment that is unknown and does not have specific localization infrastructure. Because of the low quality of inertial sensors that can be used reasonably for these two applications, state of the art VINS rely heavily on the visual information to correct at high frequency the drift of inertial sensors integration. These methods struggle when environment does not provide usable visual features, such than in low-light of texture-less areas. In the last few years, some work have been focused on using an array of magnetometers to exploit opportunistic stationary magnetic disturbances available indoor in order to deduce a velocity. This led to Magneto-inertial Dead-reckoning (MI-DR) systems that show interesting performance in their nominal conditions, even if they can be defeated when the local magnetic gradient is too low, for example outdoor. We propose in this work to fuse the information from a monocular camera with the MI-DR technique to increase the robustness of both traditional VINS and MI-DR itself. We use an inverse square root filter inspired by the MSCKF algorithm and describe its structure thoroughly in this paper. We show navigation results on a real dataset captured by a sensor fusing a commercial-grade camera with our custom MIMU (Magneto-inertial Measurment Unit) sensor. The fused estimate demonstrates higher robustness compared to pure VINS estimate, specially in areas where vision is non informative. These results could ultimately increase the working domain of mobile augmented reality systems. Full article

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

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17 pages, 2811 KiB

Open AccessArticle

Characterization of Ultrasound Energy Diffusion Due to Small-Size Damage on an Aluminum Plate Using Piezoceramic Transducers

by Guangtao Lu¹, Qian Feng², Yourong Li³, Hao Wang² and Gangbing Song^4,*

¹ Key Laboratory for Metallurgical Equipment and Control of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, China

² Key Laboratory of Earthquake Geodesy, Institute of Seismology, China Earthquake Administration, Wuhan 430071, China

³ Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering, Wuhan University of Science and Technology, Wuhan 430081, China

⁴ Smart Materials and Structures Laboratory, Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA

Sensors 2017, 17(12), 2796; https://doi.org/10.3390/s17122796 - 4 Dec 2017

Cited by 33 | Viewed by 4190

Abstract

During the propagation of ultrasonic waves in structures, there is usually energy loss due to ultrasound energy diffusion and dissipation. The aim of this research is to characterize the ultrasound energy diffusion that occurs due to small-size damage on an aluminum plate using [...] Read more.

During the propagation of ultrasonic waves in structures, there is usually energy loss due to ultrasound energy diffusion and dissipation. The aim of this research is to characterize the ultrasound energy diffusion that occurs due to small-size damage on an aluminum plate using piezoceramic transducers, for the future purpose of developing a damage detection algorithm. The ultrasonic energy diffusion coefficient is related to the damage distributed in the medium. Meanwhile, the ultrasonic energy dissipation coefficient is related to the inhomogeneity of the medium. Both are usually employed to describe the characteristics of ultrasound energy diffusion. The existence of multimodes of Lamb waves in metallic plate structures results in the asynchronous energy transport of different modes. The mode of Lamb waves has a great influence on ultrasound energy diffusion as a result, and thus has to be chosen appropriately. In order to study the characteristics of ultrasound energy diffusion in metallic plate structures, an experimental setup of an aluminum plate with a through-hole, whose diameter varies from 0.6 mm to 1.2 mm, is used as the test specimen with the help of piezoceramic transducers. The experimental results of two categories of damages at different locations reveal that the existence of damage changes the energy transport between the actuator and the sensor. Also, when there is only one dominate mode of Lamb wave excited in the structure, the ultrasound energy diffusion coefficient decreases approximately linearly with the diameter of the simulated damage. Meanwhile, the ultrasonic energy dissipation coefficient increases approximately linearly with the diameter of the simulated damage. However, when two or more modes of Lamb waves are excited, due to the existence of different group velocities between the different modes, the energy transport of the different modes is asynchronous, and the ultrasonic energy diffusion is not strictly linear with the size of the damage. Therefore, it is recommended that only one dominant mode of Lamb wave should be excited during the characterization process, in order to ensure that the linear relationship between the damage size and the characteristic parameters is maintained. In addition, the findings from this paper demonstrate the potential of developing future damage detection algorithms using the linear relationships between damage size and the ultrasound energy diffusion coefficient or ultrasonic energy dissipation coefficient when a single dominant mode is excited. Full article

(This article belongs to the Section Physical Sensors)

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8 pages, 3235 KiB

Open AccessArticle

A Low-Cost and Portable Dual-Channel Fiber Optic Surface Plasmon Resonance System

by Qiang Liu, Yun Liu, Shimeng Chen, Fang Wang and Wei Peng^*

School of Physics and Optoelectronic Technology, Dalian University of Technology, 2 Linggong Road, Ganjingzi District, Dalian 116024, China

Sensors 2017, 17(12), 2797; https://doi.org/10.3390/s17122797 - 4 Dec 2017

Cited by 21 | Viewed by 7088

Abstract

A miniaturization and integration dual-channel fiber optic surface plasmon resonance (SPR) system was proposed and demonstrated in this paper. We used a yellow light-emitting diode (LED, peak wavelength 595 nm) and built-in web camera as a light source and detector, respectively. Except for [...] Read more.

A miniaturization and integration dual-channel fiber optic surface plasmon resonance (SPR) system was proposed and demonstrated in this paper. We used a yellow light-emitting diode (LED, peak wavelength 595 nm) and built-in web camera as a light source and detector, respectively. Except for the detection channel, one of the sensors was used as a reference channel to compensate nonspecific binding and physical absorption. We packaged the LED and surface plasmon resonance (SPR) sensors together, which are flexible enough to be applied to mobile devices as a compact and portable system. Experimental results show that the normalized intensity shift and refractive index (RI) of the sample have a good linear relationship in the RI range from 1.328 to 1.348. We used this sensor to monitor the reversible, specific interaction between lectin concanavalin A (Con A) and glycoprotein ribonuclease B (RNase B), which demonstrate its capabilities of specific identification and biochemical samples concentration detection. This sensor system has potential applications in various fields, such as medical diagnosis, public health, food safety, and environment monitoring. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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21 pages, 6302 KiB

Open AccessArticle

Dynamic Modelling of Embeddable Piezoceramic Transducers

by Linsheng Huo¹

, Xu Li¹, Hongnan Li^1,2, Zhijie Wang^3,* and Gangbing Song^4,*

¹ Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China

² School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China

³ School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China

⁴ Smart Materials and Structures Laboratory, Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA

Sensors 2017, 17(12), 2801; https://doi.org/10.3390/s17122801 - 5 Dec 2017

Cited by 16 | Viewed by 3969

Abstract

Embedded Lead Zirconate Titanate (PZT) transducers have been widely used in research related to monitoring the health status of concrete structures. This paper presents a dynamic model of an embeddable PZT transducer with a waterproof layer and a protecting layer. The proposed model [...] Read more.

Embedded Lead Zirconate Titanate (PZT) transducers have been widely used in research related to monitoring the health status of concrete structures. This paper presents a dynamic model of an embeddable PZT transducer with a waterproof layer and a protecting layer. The proposed model is verified by finite-element method (FEM). Based on the proposed model, the factors influencing the dynamic property of the embeddable PZT transducers, which include the material and thickness of the protecting layer, the material and thickness of the waterproof layer, and the thickness of the PZT, are analyzed. These analyses are further validated by a series of dynamic stress transfer experiments on embeddable PZT transducers. The results show that the excitation frequency can significantly affect the stress transfer of the PZT transducer in terms of both amplitude and signal phase. The natural frequency in the poling direction for the PZT transducer is affected by the material properties and the thickness of the waterproof and protecting layers. The studies in this paper will provide a scientific basis to design embeddable PZT transducers with special functions. Full article

(This article belongs to the Section Physical Sensors)

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9 pages, 11186 KiB

Open AccessCommunication

Mapping Sensory Spots for Moderate Temperatures on the Back of Hand

by Fan Yang, Guixu Chen, Sikai Zhou, Danhong Han, Jingjing Xu and Shengyong Xu^*

Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University, Beijing 100871, China

Sensors 2017, 17(12), 2802; https://doi.org/10.3390/s17122802 - 4 Dec 2017

Cited by 5 | Viewed by 6186

Abstract

Thermosensation with thermoreceptors plays an important role in maintaining body temperature at an optimal state and avoiding potential damage caused by harmful hot or cold environmental temperatures. In this work, the locations of sensory spots for sensing moderate temperatures of 40–50 °C on [...] Read more.

Thermosensation with thermoreceptors plays an important role in maintaining body temperature at an optimal state and avoiding potential damage caused by harmful hot or cold environmental temperatures. In this work, the locations of sensory spots for sensing moderate temperatures of 40–50 °C on the back of the hands of young Chinese people were mapped in a blind-test manner with a thermal probe of 1.0 mm spatial resolution. The number of sensory spots increased along with the testing temperature; however, the surface density of sensory spots was remarkably lower than those reported previously. The locations of the spots were irregularly distributed and subject-dependent. Even for the same subject, the number and location of sensory spots were unbalanced and asymmetric between the left and right hands. The results may offer valuable information for designing artificial electronic skin and wearable devices, as well as for clinical applications. Full article

(This article belongs to the Special Issue Bio-Inspiring Sensing)

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16 pages, 1793 KiB

Open AccessArticle

Obstacle Detection as a Safety Alert in Augmented Reality Models by the Use of Deep Learning Techniques

by Dawid Połap

, Karolina Kęsik, Kamil Książek and Marcin Woźniak^*

Institute of Mathematics, Silesian University of Technology, Kaszubska 23, 44-100 Gliwice, Poland

Sensors 2017, 17(12), 2803; https://doi.org/10.3390/s17122803 - 4 Dec 2017

Cited by 26 | Viewed by 6274

Abstract

Augmented reality (AR) is becoming increasingly popular due to its numerous applications. This is especially evident in games, medicine, education, and other areas that support our everyday activities. Moreover, this kind of computer system not only improves our vision and our perception of [...] Read more.

Augmented reality (AR) is becoming increasingly popular due to its numerous applications. This is especially evident in games, medicine, education, and other areas that support our everyday activities. Moreover, this kind of computer system not only improves our vision and our perception of the world that surrounds us, but also adds additional elements, modifies existing ones, and gives additional guidance. In this article, we focus on interpreting a reality-based real-time environment evaluation for informing the user about impending obstacles. The proposed solution is based on a hybrid architecture that is capable of estimating as much incoming information as possible. The proposed solution has been tested and discussed with respect to the advantages and disadvantages of different possibilities using this type of vision. Full article

(This article belongs to the Special Issue Mobile Sensing Applications)

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14 pages, 6613 KiB

Open AccessArticle

Gas Leak Detection by Dilution of Atmospheric Oxygen

by Armin Lambrecht^*, Eric Maier, Hans-Fridtjof Pernau

, Thomas Strahl and Johannes Herbst

Fraunhofer Institute for Physical Measurement Techniques IPM, Heidenhofstr. 8, D-79110 Freiburg, Germany

Sensors 2017, 17(12), 2804; https://doi.org/10.3390/s17122804 - 5 Dec 2017

Cited by 11 | Viewed by 9145

Abstract

Gas leak detection is an important issue in infrastructure monitoring and industrial production. In this context, infrared (IR) absorption spectroscopy is a major measurement method. It can be applied in an extractive or remote detection scheme. Tunable laser spectroscopy (TLS) instruments are able [...] Read more.

Gas leak detection is an important issue in infrastructure monitoring and industrial production. In this context, infrared (IR) absorption spectroscopy is a major measurement method. It can be applied in an extractive or remote detection scheme. Tunable laser spectroscopy (TLS) instruments are able to detect CH₄ leaks with column densities below 10 ppm·m from a distance of 30 m in less than a second. However, leak detection of non-IR absorbing gases such as N₂ is not possible in this manner. Due to the fact that any leaking gas displaces or dilutes the surrounding background gas, an indirect detection is still possible. It is shown by sensitive TLS measurements of the ambient background concentration of O₂ that N₂ leaks can be localized with extractive and standoff methods for distances below 1 m. Minimum leak rates of 0.1 mbar·L/s were determined. Flow simulations confirm that the leakage gas typically effuses in a narrow jet. The sensitivity is mainly determined by ambient flow conditions. Compared to TLS detection of CH₄ at 1651 nm, the indirect method using O₂ at 761 nm is experimentally found to be less sensitive by a factor of 100. However, the well-established TLS of O₂ may become a universal tool for rapid leakage screening of vessels that contain unknown or inexpensive gases, such as N₂. Full article

(This article belongs to the Collection Gas Sensors)

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19 pages, 5294 KiB

Open AccessArticle

Contamination Event Detection with Multivariate Time-Series Data in Agricultural Water Monitoring

by Yingchi Mao^1,*, Hai Qi¹, Ping Ping¹ and Xiaofang Li²

¹ College of Computer and Information, Hohai University, Nanjing 211100, China

² School of Computer Information & Engineering, Changzhou Institute of Technology, Changzhou 213032, China

Sensors 2017, 17(12), 2806; https://doi.org/10.3390/s17122806 - 4 Dec 2017

Cited by 7 | Viewed by 4964

Abstract

Time series data of multiple water quality parameters are obtained from the water sensor networks deployed in the agricultural water supply network. The accurate and efficient detection and warning of contamination events to prevent pollution from spreading is one of the most important [...] Read more.

Time series data of multiple water quality parameters are obtained from the water sensor networks deployed in the agricultural water supply network. The accurate and efficient detection and warning of contamination events to prevent pollution from spreading is one of the most important issues when pollution occurs. In order to comprehensively reduce the event detection deviation, a spatial–temporal-based event detection approach with multivariate time-series data for water quality monitoring (M-STED) was proposed. The M-STED approach includes three parts. The first part is that M-STED adopts a Rule K algorithm to select backbone nodes as the nodes in the CDS, and forward the sensed data of multiple water parameters. The second part is to determine the state of each backbone node with back propagation neural network models and the sequential Bayesian analysis in the current timestamp. The third part is to establish a spatial model with Bayesian networks to estimate the state of the backbones in the next timestamp and trace the “outlier” node to its neighborhoods to detect a contamination event. The experimental results indicate that the average detection rate is more than 80% with M-STED and the false detection rate is lower than 9%, respectively. The M-STED approach can improve the rate of detection by about 40% and reduce the false alarm rate by about 45%, compared with the event detection with a single water parameter algorithm, S-STED. Moreover, the proposed M-STED can exhibit better performance in terms of detection delay and scalability. Full article

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

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16 pages, 429 KiB

Open AccessArticle

Node Depth Adjustment Based Target Tracking in UWSNs Using Improved Harmony Search

by Meiqin Liu^1,2,*

, Duo Zhang²

, Senlin Zhang² and Qunfei Zhang³

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

² College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China

³ School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China

Sensors 2017, 17(12), 2807; https://doi.org/10.3390/s17122807 - 4 Dec 2017

Cited by 13 | Viewed by 3791

Abstract

Underwater wireless sensor networks (UWSNs) can provide a promising solution to underwater target tracking. Due to the limited computation and bandwidth resources, only a small part of nodes are selected to track the target at each interval. How to improve tracking accuracy with [...] Read more.

Underwater wireless sensor networks (UWSNs) can provide a promising solution to underwater target tracking. Due to the limited computation and bandwidth resources, only a small part of nodes are selected to track the target at each interval. How to improve tracking accuracy with a small number of nodes is a key problem. In recent years, a node depth adjustment system has been developed and applied to issues of network deployment and routing protocol. As far as we know, all existing tracking schemes keep underwater nodes static or moving with water flow, and node depth adjustment has not been utilized for underwater target tracking yet. This paper studies node depth adjustment method for target tracking in UWSNs. Firstly, since a Fisher Information Matrix (FIM) can quantify the estimation accuracy, its relation to node depth is derived as a metric. Secondly, we formulate the node depth adjustment as an optimization problem to determine moving depth of activated node, under the constraint of moving range, the value of FIM is used as objective function, which is aimed to be minimized over moving distance of nodes. Thirdly, to efficiently solve the optimization problem, an improved Harmony Search (HS) algorithm is proposed, in which the generating probability is modified to improve searching speed and accuracy. Finally, simulation results are presented to verify performance of our scheme. Full article

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

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14 pages, 3030 KiB

Open AccessArticle

Frequency-Locked Detector Threshold Setting Criteria Based on Mean-Time-To-Lose-Lock (MTLL) for GPS Receivers

by Tian Jin¹

, Heliang Yuan¹

, Na Zhao¹, Honglei Qin^1,*, Kewen Sun² and Yuanfa Ji³

¹ School of Electronic and Information Engineering, Beihang University, Beijing 100191, China

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

³ Guangxi Key Laboratory of Precision Navigation Technology and Application, Guilin 541004, China

Sensors 2017, 17(12), 2808; https://doi.org/10.3390/s17122808 - 4 Dec 2017

Cited by 4 | Viewed by 4354

Abstract

Frequency-locked detector (FLD) has been widely utilized in tracking loops of Global Positioning System (GPS) receivers to indicate their locking status. The relation between FLD and lock status has been seldom discussed. The traditional PLL experience is not suitable for FLL. In this [...] Read more.

Frequency-locked detector (FLD) has been widely utilized in tracking loops of Global Positioning System (GPS) receivers to indicate their locking status. The relation between FLD and lock status has been seldom discussed. The traditional PLL experience is not suitable for FLL. In this paper, the threshold setting criteria for frequency-locked detector in the GPS receiver has been proposed by analyzing statistical characteristic of FLD output. The approximate probability distribution of frequency-locked detector is theoretically derived by using a statistical approach, which reveals the relationship between probabilities of frequency-locked detector and the carrier-to-noise ratio (C/N₀) of the received GPS signal. The relationship among mean-time-to-lose-lock (MTLL), detection threshold and lock probability related to C/N₀ can be further discovered by utilizing this probability. Therefore, a theoretical basis for threshold setting criteria in frequency locked loops for GPS receivers is provided based on mean-time-to-lose-lock analysis. Full article

(This article belongs to the Special Issue Sensor Signal and Information Processing)

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10 pages, 12003 KiB

Open AccessArticle

Analysis of Fresnel Zone Plates Focusing Dependence on Operating Frequency

by José Miguel Fuster^1,2, Pilar Candelas^3,4, Sergio Castiñeira-Ibáñez^3,5, Sergio Pérez-López^2,3 and Constanza Rubio^3,4,*

¹ ETSI Telecomunicación, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain

² Departamento de Comunicaciones, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain

³ Centro de Tecnologías Físicas, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain

⁴ Departamento de Física Aplicada, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain

⁵ Departamento de Ingeniería Electrónica, Universitat de València, Avd. de la Universitat s/n, Burjassot, 46100 Valencia, Spain

Sensors 2017, 17(12), 2809; https://doi.org/10.3390/s17122809 - 5 Dec 2017

Cited by 25 | Viewed by 8647

Abstract

The focusing properties of Fresnel Zone Plates (FZPs) against frequency are analyzed in this work. It is shown that the FZP focal length depends almost linearly on the operating frequency. Focal depth and focal distortion are also considered, establishing a limit on the [...] Read more.

The focusing properties of Fresnel Zone Plates (FZPs) against frequency are analyzed in this work. It is shown that the FZP focal length depends almost linearly on the operating frequency. Focal depth and focal distortion are also considered, establishing a limit on the frequency span at which the operating frequency can be shifted. An underwater FZP ultrasound focusing system is demonstrated, and experimental results agree with the theoretical analysis and simulations. Full article

(This article belongs to the Section Physical Sensors)

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18 pages, 936 KiB

Open AccessArticle

A Study about Kalman Filters Applied to Embedded Sensors

by Aurélien Valade^1,2,*, Pascal Acco¹

, Pierre Grabolosa² and Jean-Yves Fourniols¹

¹ LAAS-CNRS, Université de Toulouse, CNRS, INSA, 31031 Toulouse, France

² Institut Méditerranéen d’Enseignement et de Recherche en Informatique et Robotique, 66004 Perpignan, France

Sensors 2017, 17(12), 2810; https://doi.org/10.3390/s17122810 - 5 Dec 2017

Cited by 65 | Viewed by 8474

Abstract

Over the last decade, smart sensors have grown in complexity and can now handle multiple measurement sources. This work establishes a methodology to achieve better estimates of physical values by processing raw measurements within a sensor using multi-physical models and Kalman filters for [...] Read more.

Over the last decade, smart sensors have grown in complexity and can now handle multiple measurement sources. This work establishes a methodology to achieve better estimates of physical values by processing raw measurements within a sensor using multi-physical models and Kalman filters for data fusion. A driving constraint being production cost and power consumption, this methodology focuses on algorithmic complexity while meeting real-time constraints and improving both precision and reliability despite low power processors limitations. Consequently, processing time available for other tasks is maximized. The known problem of estimating a 2D orientation using an inertial measurement unit with automatic gyroscope bias compensation will be used to illustrate the proposed methodology applied to a low power STM32L053 microcontroller. This application shows promising results with a processing time of 1.18 ms at 32 MHz with a 3.8% CPU usage due to the computation at a 26 Hz measurement and estimation rate. Full article

(This article belongs to the Special Issue Internet of Wearable and Implantable Medical Things: Theory and Applications)

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11 pages, 5559 KiB

Open AccessArticle

Dual-Wavelength Laser Speckle Contrast Imaging (dwLSCI) Improves Chronic Measurement of Superficial Blood Flow in Hands

by Lingke Zhang¹, Li Ding², Miao Li¹, Xiaoli Zhang², Diansan Su^3,*, Jie Jia² and Peng Miao¹

¹ Biomedical Engineering Institute, School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China

² Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai 200040, China

³ Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China

Sensors 2017, 17(12), 2811; https://doi.org/10.3390/s17122811 - 5 Dec 2017

Cited by 13 | Viewed by 6982

Abstract

Laser speckle contrast imaging (LSCI) has been widely used to determine blood flow and perfusion in biological tissues. The physical model of traditional LSCI ignores the effects of scattering property distribution in relation to speckle correlation time τ_c and blood flow v [...] Read more.

Laser speckle contrast imaging (LSCI) has been widely used to determine blood flow and perfusion in biological tissues. The physical model of traditional LSCI ignores the effects of scattering property distribution in relation to speckle correlation time τ_c and blood flow v, which further results in biased estimation. In this study, we developed a dual-wavelength laser speckle contrast imaging (dwLSCI) method and a portable device for imaging the blood flow and tissue perfusion in human hands. Experimental data showed that dwLSCI could retrieve the vein vasculatures under the surface skin, and it further provided accurate measurements of vein blood flow signals, tissue perfusion signals, and fingertip perfusion signals, which assist with assessments of rehabilitation therapy for stroke patients. Fingertip perfusion signals demonstrated better performance in early assessments, while vein blood flow signals assisted the Fugl–Meyer Assessment Scale (FMA) and the Wolf Motor Function Test (WMFT) behavior assessments. As a general noninvasive imaging method, dwLSCI can be applied in clinical studies related to hand functions combined with behavior assessments. Full article

(This article belongs to the Special Issue Novel Sensors for Bioimaging)

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21 pages, 1470 KiB

Open AccessFeature PaperArticle

Energy Management in Smart Cities Based on Internet of Things: Peak Demand Reduction and Energy Savings

by Chinmaya Mahapatra^1,*

, Akshaya Kumar Moharana² and Victor C. M. Leung¹

¹ Department of Electrical and Computer Engineering, The University of British Columbia (UBC), 2332 Main Mall, Vancouver, BC V6T 1Z4, Canada

² Power Systems Studies, Powertech Labs Inc., Surrey, BC V3W 7R7, Canada

Sensors 2017, 17(12), 2812; https://doi.org/10.3390/s17122812 - 5 Dec 2017

Cited by 113 | Viewed by 9729

Abstract

Around the globe, innovation with integrating information and communication technologies (ICT) with physical infrastructure is a top priority for governments in pursuing smart, green living to improve energy efficiency, protect the environment, improve the quality of life, and bolster economy competitiveness. Cities today [...] Read more.

Around the globe, innovation with integrating information and communication technologies (ICT) with physical infrastructure is a top priority for governments in pursuing smart, green living to improve energy efficiency, protect the environment, improve the quality of life, and bolster economy competitiveness. Cities today faces multifarious challenges, among which energy efficiency of homes and residential dwellings is a key requirement. Achieving it successfully with the help of intelligent sensors and contextual systems would help build smart cities of the future. In a Smart home environment Home Energy Management plays a critical role in finding a suitable and reliable solution to curtail the peak demand and achieve energy conservation. In this paper, a new method named as Home Energy Management as a Service (HEMaaS) is proposed which is based on neural network based Q-learning algorithm. Although several attempts have been made in the past to address similar problems, the models developed do not cater to maximize the user convenience and robustness of the system. In this paper, authors have proposed an advanced Neural Fitted Q-learning method which is self-learning and adaptive. The proposed method provides an agile, flexible and energy efficient decision making system for home energy management. A typical Canadian residential dwelling model has been used in this paper to test the proposed method. Based on analysis, it was found that the proposed method offers a fast and viable solution to reduce the demand and conserve energy during peak period. It also helps reducing the carbon footprint of residential dwellings. Once adopted, city blocks with significant residential dwellings can significantly reduce the total energy consumption by reducing or shifting their energy demand during peak period. This would definitely help local power distribution companies to optimize their resources and keep the tariff low due to curtailment of peak demand. Full article

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

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12 pages, 4982 KiB

Open AccessArticle

Real-Time and In-Flow Sensing Using a High Sensitivity Porous Silicon Microcavity-Based Sensor

by Raffaele Caroselli

, David Martín Sánchez

, Salvador Ponce Alcántara, Francisco Prats Quilez, Luis Torrijos Morán and Jaime García-Rupérez^*

Nanophotonics Technology Center (NTC), Universitat Politècnica de València, 46022 Valencia, Spain

Sensors 2017, 17(12), 2813; https://doi.org/10.3390/s17122813 - 5 Dec 2017

Cited by 28 | Viewed by 5939

Abstract

Porous silicon seems to be an appropriate material platform for the development of high-sensitivity and low-cost optical sensors, as their porous nature increases the interaction with the target substances, and their fabrication process is very simple and inexpensive. In this paper, we present [...] Read more.

Porous silicon seems to be an appropriate material platform for the development of high-sensitivity and low-cost optical sensors, as their porous nature increases the interaction with the target substances, and their fabrication process is very simple and inexpensive. In this paper, we present the experimental development of a porous silicon microcavity sensor and its use for real-time in-flow sensing application. A high-sensitivity configuration was designed and then fabricated, by electrochemically etching a silicon wafer. Refractive index sensing experiments were realized by flowing several dilutions with decreasing refractive indices, and measuring the spectral shift in real-time. The porous silicon microcavity sensor showed a very linear response over a wide refractive index range, with a sensitivity around 1000 nm/refractive index unit (RIU), which allowed us to directly detect refractive index variations in the 10⁻⁷ RIU range. Full article

(This article belongs to the Special Issue Sensors for Health Monitoring and Disease Diagnosis)

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11 pages, 4071 KiB

Open AccessArticle

Application of a Saddle-Type Eddy Current Sensor in Steel Ball Surface-Defect Inspection

by Huayu Zhang¹

, Mingming Zhong¹, Fengqin Xie^2,* and Maoyong Cao^3,*

¹ College of Mechanical and electronic Engineering, Shandong University of Science and Technology, Qingdao 266590, China

² College of Transportation, Shandong University of Science and Technology, Qingdao 266590, China

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

Sensors 2017, 17(12), 2814; https://doi.org/10.3390/s17122814 - 5 Dec 2017

Cited by 14 | Viewed by 6118

Abstract

Steel ball surface-defect inspection was performed by using a new saddle-type eddy current sensor (SECS), which included a saddle coil and a signal conditioning circuit. The saddle coil was directly wound on the steel ball’s outer bracket in a semi-circumferential direction. Driven by [...] Read more.

Steel ball surface-defect inspection was performed by using a new saddle-type eddy current sensor (SECS), which included a saddle coil and a signal conditioning circuit. The saddle coil was directly wound on the steel ball’s outer bracket in a semi-circumferential direction. Driven by a friction wheel, the test steel ball rotated in a one-dimensional direction, such that the steel ball surface was fully scanned by the SECS. There were two purposes for using the SECS in the steel ball inspection system: one was to reduce the complexity of the unfolding wheel of the surface deployment mechanism, and the other was to reduce the difficulty of sensor processing and installation. Experiments were carried out on bearing steel balls in diameter of 8 mm with three types of representative and typical defects by using the SECS, and the results showed that the inspection system can detect surface defects as small as 0.05 mm in width and 0.1 mm in depth with high-repetition detection accuracy, and the detection efficiency of 5 pcs/s, which meet the requirement for inspecting ISO grade 10 bearing steel balls. The feasibility of detecting steel ball surface defects by SECS was verified. Full article

(This article belongs to the Special Issue Magnetic Sensors and Their Applications)

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16 pages, 1460 KiB

Open AccessArticle

Lightweight Biometric Sensing for Walker Classification Using Narrowband RF Links

by Tong Liu^1,*

and Zhuo-qian Liang²

¹ Department of Electronics Engineering, Huizhou University, Huizhou 516001, China

² College of Information Science and Technology, Jinan University, Guangzhou 510632, China

Sensors 2017, 17(12), 2815; https://doi.org/10.3390/s17122815 - 5 Dec 2017

Cited by 6 | Viewed by 4361

Abstract

This article proposes a lightweight biometric sensing system using ubiquitous narrowband radio frequency (RF) links for path-dependent walker classification. The fluctuated received signal strength (RSS) sequence generated by human motion is used for feature representation. To capture the most discriminative characteristics of individuals, [...] Read more.

This article proposes a lightweight biometric sensing system using ubiquitous narrowband radio frequency (RF) links for path-dependent walker classification. The fluctuated received signal strength (RSS) sequence generated by human motion is used for feature representation. To capture the most discriminative characteristics of individuals, a three-layer RF sensing network is organized for building multiple sampling links at the most common heights of upper limbs, thighs, and lower legs. The optimal parameters of sensing configuration, such as the height of link location and number of fused links, are investigated to improve sensory data distinctions among subjects, and the experimental results suggest that the synergistic sensing by using multiple links can contribute a better performance. This is the new consideration of using RF links in building a biometric sensing system. In addition, two types of classification methods involving vector quantization (VQ) and hidden Markov models (HMMs) are developed and compared for closed-set walker recognition and verification. Experimental studies in indoor line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios are conducted to validate the proposed method. Full article

(This article belongs to the Special Issue Sensor Signal and Information Processing)

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13 pages, 8714 KiB

Open AccessArticle

A 45 nm Stacked CMOS Image Sensor Process Technology for Submicron Pixel

by Seiji Takahashi^*, Yi-Min Huang, Jhy-Jyi Sze, Tung-Ting Wu, Fu-Sheng Guo, Wei-Cheng Hsu, Tung-Hsiung Tseng, King Liao, Chin-Chia Kuo, Tzu-Hsiang Chen, Wei-Chieh Chiang, Chun-Hao Chuang, Keng-Yu Chou, Chi-Hsien Chung, Kuo-Yu Chou, Chien-Hsien Tseng, Chuan-Joung Wang and Dun-Nien Yaung

Taiwan Semiconductor Manufacturing Company, No. 8, Li-Hsin Rd. 6, Hsinchu Science Park, Hsinchu 300, Taiwan

Sensors 2017, 17(12), 2816; https://doi.org/10.3390/s17122816 - 5 Dec 2017

Cited by 33 | Viewed by 14804

Abstract

A submicron pixel’s light and dark performance were studied by experiment and simulation. An advanced node technology incorporated with a stacked CMOS image sensor (CIS) is promising in that it may enhance performance. In this work, we demonstrated a low dark current of [...] Read more.

A submicron pixel’s light and dark performance were studied by experiment and simulation. An advanced node technology incorporated with a stacked CMOS image sensor (CIS) is promising in that it may enhance performance. In this work, we demonstrated a low dark current of 3.2 e⁻/s at 60 °C, an ultra-low read noise of 0.90 e⁻·rms, a high full well capacity (FWC) of 4100 e⁻, and blooming of 0.5% in 0.9 μm pixels with a pixel supply voltage of 2.8 V. In addition, the simulation study result of 0.8 μm pixels is discussed. Full article

(This article belongs to the Special Issue Special Issue on the 2017 International Image Sensor Workshop (IISW))

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16 pages, 5533 KiB

Open AccessArticle

Monitoring Traffic Information with a Developed Acceleration Sensing Node

by Zhoujing Ye¹, Linbing Wang^1,2,*, Wen Xu¹, Zhifei Gao¹ and Guannan Yan¹

¹ National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing 100083, China

² Joint USTB-Virginia Tech Lab on Multifunctional Materials, USTB, Beijing 100083, China & Virginia Tech, Blacksburg, VA 24061, USA

Sensors 2017, 17(12), 2817; https://doi.org/10.3390/s17122817 - 5 Dec 2017

Cited by 26 | Viewed by 6382

Abstract

In this paper, an acceleration sensing node for pavement vibration was developed to monitor traffic information, including vehicle speed, vehicle types, and traffic flow, where a hardware design with low energy consumption and node encapsulation could be accomplished. The service performance of the [...] Read more.

In this paper, an acceleration sensing node for pavement vibration was developed to monitor traffic information, including vehicle speed, vehicle types, and traffic flow, where a hardware design with low energy consumption and node encapsulation could be accomplished. The service performance of the sensing node was evaluated, by methods including waterproof test, compression test, sensing performance analysis, and comparison test. The results demonstrate that the sensing node is low in energy consumption, high in strength, IPX8 waterproof, and high in sensitivity and resolution. These characteristics can be applied to practical road environments. Two sensing nodes were spaced apart in the direction of travelling. In the experiment, three types of vehicles passed by the monitoring points at several different speeds and values of d (the distance between the sensor and the nearest tire center line). Based on cross-correlation with kernel pre-smoothing, a calculation method was applied to process the raw data. New algorithms for traffic flow, speed, and axle length were proposed. Finally, the effects of vehicle speed, vehicle weight, and d value on acceleration amplitude were statistically evaluated. It was found that the acceleration sensing node can be used for traffic flow, vehicle speed, and other types of monitoring. Full article

(This article belongs to the Special Issue Sensor Networks for Smart Roads)

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21 pages, 2955 KiB

Open AccessArticle

Dynamic Spectrum Access for Internet of Things Service in Cognitive Radio-Enabled LPWANs

by Bongkyo Moon

Department of Computer Science and Engineering, Dongguk University-Seoul, 30 Pildong-ro 1 gil, Jung-gu, Seoul 04620, Korea

Sensors 2017, 17(12), 2818; https://doi.org/10.3390/s17122818 - 5 Dec 2017

Cited by 48 | Viewed by 7958

Abstract

In this paper, we focus on a dynamic spectrum access strategy for Internet of Things (IoT) applications in two types of radio systems: cellular networks and cognitive radio-enabled low power wide area networks (CR-LPWANs). The spectrum channel contention between the licensed cellular networks [...] Read more.

In this paper, we focus on a dynamic spectrum access strategy for Internet of Things (IoT) applications in two types of radio systems: cellular networks and cognitive radio-enabled low power wide area networks (CR-LPWANs). The spectrum channel contention between the licensed cellular networks and the unlicensed CR-LPWANs, which work with them, only takes place within the cellular radio spectrum range. Our aim is to maximize the spectrum capacity for the unlicensed users while ensuring that it never interferes with the licensed network. Therefore, in this paper we propose a dynamic spectrum access strategy for CR-LPWANs operating in both licensed and unlicensed bands. The simulation and the numerical analysis by using a matrix geometric approach for the strategy are presented. Finally, we obtain the blocking probability of the licensed users, the mean dwell time of the unlicensed user, and the total carried traffic and combined service quality for the licensed and unlicensed users. The results show that the proposed strategy can maximize the spectrum capacity for the unlicensed users using IoT applications as well as keep the service quality of the licensed users independent of them. Full article

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

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21 pages, 21845 KiB

Open AccessArticle

Vision System for Coarsely Estimating Motion Parameters for Unknown Fast Moving Objects in Space

by Min Chen^* and Koichi Hashimoto

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

Sensors 2017, 17(12), 2820; https://doi.org/10.3390/s17122820 - 5 Dec 2017

Cited by 3 | Viewed by 4274

Abstract

Motivated by biological interests in analyzing navigation behaviors of flying animals, we attempt to build a system measuring their motion states. To do this, in this paper, we build a vision system to detect unknown fast moving objects within a given space, calculating [...] Read more.

Motivated by biological interests in analyzing navigation behaviors of flying animals, we attempt to build a system measuring their motion states. To do this, in this paper, we build a vision system to detect unknown fast moving objects within a given space, calculating their motion parameters represented by positions and poses. We proposed a novel method to detect reliable interest points from images of moving objects, which can be hardly detected by general purpose interest point detectors. 3D points reconstructed using these interest points are then grouped and maintained for detected objects, according to a careful schedule, considering appearance and perspective changes. In the estimation step, a method is introduced to adapt the robust estimation procedure used for dense point set to the case for sparse set, reducing the potential risk of greatly biased estimation. Experiments are conducted against real scenes, showing the capability of the system of detecting multiple unknown moving objects and estimating their positions and poses. Full article

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

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21 pages, 6665 KiB

Open AccessArticle

Heterogeneous Data Fusion Method to Estimate Travel Time Distributions in Congested Road Networks

by Chaoyang Shi^1,2,3, Bi Yu Chen^1,2,3,*

, William H. K. Lam³ and Qingquan Li^1,2,4,*

¹ State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430072, China

² Collaborative Innovation Center of Geospatial Technology, Wuhan 430079, China

³ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China

⁴ Shenzhen Key Laboratory of Spatial Smart Sensing and Services, Shenzhen University, Shenzhen 518060, China

Sensors 2017, 17(12), 2822; https://doi.org/10.3390/s17122822 - 6 Dec 2017

Cited by 15 | Viewed by 5721

Abstract

Travel times in congested urban road networks are highly stochastic. Provision of travel time distribution information, including both mean and variance, can be very useful for travelers to make reliable path choice decisions to ensure higher probability of on-time arrival. To this end, [...] Read more.

Travel times in congested urban road networks are highly stochastic. Provision of travel time distribution information, including both mean and variance, can be very useful for travelers to make reliable path choice decisions to ensure higher probability of on-time arrival. To this end, a heterogeneous data fusion method is proposed to estimate travel time distributions by fusing heterogeneous data from point and interval detectors. In the proposed method, link travel time distributions are first estimated from point detector observations. The travel time distributions of links without point detectors are imputed based on their spatial correlations with links that have point detectors. The estimated link travel time distributions are then fused with path travel time distributions obtained from the interval detectors using Dempster-Shafer evidence theory. Based on fused path travel time distribution, an optimization technique is further introduced to update link travel time distributions and their spatial correlations. A case study was performed using real-world data from Hong Kong and showed that the proposed method obtained accurate and robust estimations of link and path travel time distributions in congested road networks. Full article

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

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20 pages, 3054 KiB

Open AccessArticle

Parameter Search Algorithms for Microwave Radar-Based Breast Imaging: Focal Quality Metrics as Fitness Functions

by Declan O’Loughlin^1,*

, Bárbara L. Oliveira¹

, Muhammad Adnan Elahi¹

, Martin Glavin¹

, Edward Jones¹, Milica Popović² and Martin O’Halloran¹

¹ Electrical and Electronic Engineering, National University of Ireland Galway, H91 TK33 Galway, Ireland

² McGill University, Montréal, QC, Canada H3A 0G4

Sensors 2017, 17(12), 2823; https://doi.org/10.3390/s17122823 - 6 Dec 2017

Cited by 31 | Viewed by 6079

Abstract

Inaccurate estimation of average dielectric properties can have a tangible impact on microwave radar-based breast images. Despite this, recent patient imaging studies have used a fixed estimate although this is known to vary from patient to patient. Parameter search algorithms are a promising [...] Read more.

Inaccurate estimation of average dielectric properties can have a tangible impact on microwave radar-based breast images. Despite this, recent patient imaging studies have used a fixed estimate although this is known to vary from patient to patient. Parameter search algorithms are a promising technique for estimating the average dielectric properties from the reconstructed microwave images themselves without additional hardware. In this work, qualities of accurately reconstructed images are identified from point spread functions. As the qualities of accurately reconstructed microwave images are similar to the qualities of focused microscopic and photographic images, this work proposes the use of focal quality metrics for average dielectric property estimation. The robustness of the parameter search is evaluated using experimental dielectrically heterogeneous phantoms on the three-dimensional volumetric image. Based on a very broad initial estimate of the average dielectric properties, this paper shows how these metrics can be used as suitable fitness functions in parameter search algorithms to reconstruct clear and focused microwave radar images. Full article

(This article belongs to the Special Issue Sensors for Microwave Imaging and Detection)

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9 pages, 4740 KiB

Open AccessArticle

Fatigue Damage Evaluation of Short Carbon Fiber Reinforced Plastics Based on Phase Information of Thermoelastic Temperature Change

by Daiki Shiozawa^1,*, Takahide Sakagami¹, Yu Nakamura¹, Shinichi Nonaka² and Kenichi Hamada²

¹ Department of Mechanical Engineering, Kobe University, Kobe 657-8501, Japan

² DIC Corporation, Tokyo 103-8233, Japan

Sensors 2017, 17(12), 2824; https://doi.org/10.3390/s17122824 - 6 Dec 2017

Cited by 12 | Viewed by 5788

Abstract

Carbon fiber-reinforced plastic (CFRP) is widely used for structural members of transportation vehicles such as automobile, aircraft, or spacecraft, utilizing its excellent specific strength and specific rigidity in contrast with the metal. Short carbon fiber composite materials are receiving a lot of attentions [...] Read more.

Carbon fiber-reinforced plastic (CFRP) is widely used for structural members of transportation vehicles such as automobile, aircraft, or spacecraft, utilizing its excellent specific strength and specific rigidity in contrast with the metal. Short carbon fiber composite materials are receiving a lot of attentions because of their excellent moldability and productivity, however they show complicated behaviors in fatigue fracture due to the random fibers orientation. In this study, thermoelastic stress analysis (TSA) using an infrared thermography was applied to evaluate fatigue damage in short carbon fiber composites. The distribution of the thermoelastic temperature change was measured during the fatigue test, as well as the phase difference between the thermoelastic temperature change and applied loading signal. Evolution of fatigue damage was detected from the distribution of thermoelastic temperature change according to the thermoelastic damage analysis (TDA) procedure. It was also found that fatigue damage evolution was more clearly detected than before by the newly developed thermoelastic phase damage analysis (TPDA) in which damaged area was emphasized in the differential phase delay images utilizing the property that carbon fiber shows opposite phase thermoelastic temperature change. Full article

(This article belongs to the Special Issue Non Destructive Testing and Evaluation of Aerospace Composite Structures)

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8 pages, 1327 KiB

Open AccessArticle

Invisible Security Printing on Photoresist Polymer Readable by Terahertz Spectroscopy

by Hee Jun Shin¹, Min-Cheol Lim¹, Kisang Park^1,2, Sae-Hyung Kim², Sung-Wook Choi¹ and Gyeongsik Ok^1,*

¹ Research Group of Food Safety, Korea Food Research Institute, 245, Nongsaengmyeong-ro, Iseo-myeon, Wanju-gun, Jeollabuk-do 55365, Korea

² Department of Molecular Science and Technology, Ajou University, Suwon 16499, Korea

Sensors 2017, 17(12), 2825; https://doi.org/10.3390/s17122825 - 6 Dec 2017

Cited by 13 | Viewed by 5889

Abstract

We experimentally modulate the refractive index and the absorption coefficient of an SU-8 dry film in the terahertz region by UV light (362 nm) exposure with time dependency. Consequently, the refractive index of SU-8 film is increased by approximately 6% after UV light [...] Read more.

We experimentally modulate the refractive index and the absorption coefficient of an SU-8 dry film in the terahertz region by UV light (362 nm) exposure with time dependency. Consequently, the refractive index of SU-8 film is increased by approximately 6% after UV light exposure. Moreover, the absorption coefficient also changes significantly. Using the reflective terahertz imaging technique, in addition, we can read security information printed by UV treatment on an SU-8 film that is transparent in the visible spectrum. From these results, we successfully demonstrate security printing and reading by using photoresist materials and the terahertz technique. This investigation would provide a new insight into anti-counterfeiting applications in fields that need security. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 2985 KiB

Open AccessArticle

Co-Cultured Continuously Bioluminescent Human Cells as Bioreporters for the Detection of Prodrug Therapeutic Impact Pre- and Post-Metabolism

by Tingting Xu¹, Michael Conway², Ashley Frank³, Steven Ripp^1,2, Gary Sayler² and Dan Close^2,*

¹ Center for Environmental Biotechnology, The University of Tennessee, Knoxville, TN 37996, USA

² 490 BioTech, Inc., Knoxville, TN 37996, USA

³ Entomology Department, Cornell University, Ithaca, NY 14850, USA

Sensors 2017, 17(12), 2827; https://doi.org/10.3390/s17122827 - 6 Dec 2017

Cited by 2 | Viewed by 3743

Abstract

Modern drug discovery workflows require assay systems capable of replicating the complex interactions of multiple tissue types, but that can still function under high throughput conditions. In this work, we evaluate the use of substrate-free autobioluminescence in human cell lines to support the [...] Read more.

Modern drug discovery workflows require assay systems capable of replicating the complex interactions of multiple tissue types, but that can still function under high throughput conditions. In this work, we evaluate the use of substrate-free autobioluminescence in human cell lines to support the performance of these assays with reduced economical and logistical restrictions relative to substrate-requiring bioluminescent reporter systems. The use of autobioluminescence was found to support assay functionality similar to existing luciferase reporter targets. The autobioluminescent assay format was observed to correlate strongly with general metabolic activity markers such as ATP content and the presence of reactive oxygen species, but not with secondary markers such as glutathione depletion. At the transcriptional level, autobioluminescent dynamics were most closely associated with expression of the CYP1A1 phase I detoxification pathway. These results suggest constitutively autobioluminescent cells can function as general metabolic activity bioreporters, while pairing expression of the autobioluminescent phenotype to detoxification pathway specific promoters could create more specific sensor systems. Full article

(This article belongs to the Special Issue Novel Sensors for Bioimaging)

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17 pages, 3894 KiB

Open AccessArticle

Indoors Locality Positioning Using Cognitive Distances and Directions

by Yankun Wang^1,2, Hong Fan^1,2,* and Ruizhi Chen^1,2

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, Wuhan University, Wuhan 430079, China

Sensors 2017, 17(12), 2828; https://doi.org/10.3390/s17122828 - 7 Dec 2017

Cited by 7 | Viewed by 3933

Abstract

Spatial relationships are crucial to spatial knowledge representation, such as positioning localities. However, minimal attention has been devoted to positioning localities indoors with locality description. Distance and direction relations are generally used when positioning localities, namely, translating descriptive localities into spatially explicit ones. [...] Read more.

Spatial relationships are crucial to spatial knowledge representation, such as positioning localities. However, minimal attention has been devoted to positioning localities indoors with locality description. Distance and direction relations are generally used when positioning localities, namely, translating descriptive localities into spatially explicit ones. We propose a joint probability function to model locality distribution to address the uncertainty of positioning localities. The joint probability function consists of distance and relative direction membership functions. We propose definitions and restrictions for the use of the joint probability function to make the locality distribution highly practical. We also evaluate the performance of our approach through indoor experiments. Test results demonstrate that a positioning accuracy of 3.5 m can be achieved with the semantically derived spatial relationships. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 5452 KiB

Open AccessArticle

A “Skylight” Simulator for HWIL Simulation of Hyperspectral Remote Sensing

by Huijie Zhao, Bolun Cui, Guorui Jia^*

, Xudong Li, Chao Zhang and Xinyang Zhang

School of Instrumentation Science & Opto-electronics Engineering, Key Laboratory of Precision Opto-Mechatronics Technology, Beihang University, Ministry of Education, 37# Xueyuan Road, Haidian District, Beijing 100191, China

Sensors 2017, 17(12), 2829; https://doi.org/10.3390/s17122829 - 6 Dec 2017

Cited by 7 | Viewed by 4930

Abstract

Even though digital simulation technology has been widely used in the last two decades, hardware-in-the-loop (HWIL) simulation is still an indispensable method for spectral uncertainty research of ground targets. However, previous facilities mainly focus on the simulation of panchromatic imaging. Therefore, neither the [...] Read more.

Even though digital simulation technology has been widely used in the last two decades, hardware-in-the-loop (HWIL) simulation is still an indispensable method for spectral uncertainty research of ground targets. However, previous facilities mainly focus on the simulation of panchromatic imaging. Therefore, neither the spectral nor the spatial performance is enough for hyperspectral simulation. To improve the accuracy of illumination simulation, a new dome-like skylight simulator is designed and developed to fit the spatial distribution and spectral characteristics of a real skylight for the wavelength from 350 nm to 2500 nm. The simulator’s performance was tested using a spectroradiometer with different accessories. The spatial uniformity is greater than 0.91. The spectral mismatch decreases to 1/243 of the spectral mismatch of the Imagery Simulation Facility (ISF). The spatial distribution of radiance can be adjusted, and the accuracy of the adjustment is greater than 0.895. The ability of the skylight simulator is also demonstrated by comparing radiometric quantities measured in the skylight simulator with those in a real skylight in Beijing. Full article

(This article belongs to the Special Issue Multispectral and Hyperspectral Instrumentation)

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13 pages, 1510 KiB

Open AccessArticle

Detection of Water Content in Rapeseed Leaves Using Terahertz Spectroscopy

by Pengcheng Nie^1,2, Fangfang Qu¹, Lei Lin¹, Tao Dong¹, Yong He^1,*

, Yongni Shao³ and Yi Zhang⁴

¹ College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China

² State Key Laboratory of Modern Optical Instruments, Zhejiang University, Hangzhou 310027, China

³ Shanghai Key Lab of Modern Optical System, University of Shanghai for Science and Technology No. 516, Jungong Road, Shanghai 200093, China

⁴ Daheng Scitech Mansion, No. 3 Suzhou Street, Haidian District, Beijing 100080, China

Sensors 2017, 17(12), 2830; https://doi.org/10.3390/s17122830 - 6 Dec 2017

Cited by 52 | Viewed by 6232

Abstract

The terahertz (THz) spectra of rapeseed leaves with different water content (WC) were investigated. The transmission and absorption spectra in the range of 0.3–2 THz were measured by using THz time-domain spectroscopy. The mean transmittance and absorption coefficients were applied to analyze the [...] Read more.

The terahertz (THz) spectra of rapeseed leaves with different water content (WC) were investigated. The transmission and absorption spectra in the range of 0.3–2 THz were measured by using THz time-domain spectroscopy. The mean transmittance and absorption coefficients were applied to analyze the change regulation of WC. In addition, the Savitzky-Golay method was performed to preprocess the spectra. Then, the partial least squares (PLS), kernel PLS (KPLS), and Boosting-PLS were conducted to establish models for predicting WC based on the processed transmission and absorption spectra. Reliable results were obtained by these three methods. KPLS generated the best prediction accuracy of WC. The prediction coefficient correlation (Rval) and root mean square error (RMSEP) of KPLS based on transmission were Rval = 0.8508, RMSEP = 0.1015, and that based on absorption were Rval = 0.8574, RMSEP = 0.1009. Results demonstrated that THz spectroscopy combined with modeling methods provided an efficient and feasible technique for detecting plant physiological information. Full article

(This article belongs to the Special Issue Spectroscopy Based Sensors)

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16 pages, 13671 KiB

Open AccessArticle

Microwave Non-Destructive Inspection and Prediction of Modulus of Rupture and Modulus of Elasticity of Engineered Cementitious Composites (ECCs) Using Dual-Frequency Correlation

by Kwok L. Chung¹

, Chunwei Zhang^1,*, Yuanyuan Li¹

, Li Sun² and Mohamed Ghannam³

¹ School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China

² School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China

³ Structural Engineering Department, Faculty of Engineering, Mansoura University, Mansoura, Dakahlia 35516, Egypt

Sensors 2017, 17(12), 2831; https://doi.org/10.3390/s17122831 - 6 Dec 2017

Cited by 12 | Viewed by 4853

Abstract

This research article presents dual-frequency correlation models for predicting the growth of elasticity and flexural strength of engineered cementitious composites (ECCs) using microwave nondestructive inspection technique. Parallel measurements of microwave properties and mechanical properties of ECC specimens were firstly undertaken in the sense [...] Read more.

This research article presents dual-frequency correlation models for predicting the growth of elasticity and flexural strength of engineered cementitious composites (ECCs) using microwave nondestructive inspection technique. Parallel measurements of microwave properties and mechanical properties of ECC specimens were firstly undertaken in the sense of cross-disciplinary experiments. Regression models were developed via means of nonlinear regression to the measured data. The purpose of the study is: (i) to monitor the flexural strength and elasticity growth; and (ii) to predict their mature values under the influence of different initial water contents, via microwave effective conductance at early ages. It has been demonstrated that both the modulus of rupture (MOR) and modulus of elasticity (MOE) can be accurately modeled and correlated by microwave conductance using exponential functions. The moduli developed as a function of conductance whereas the regression coefficient exhibited a linear relation with water-to-binder ratio. These findings have highlighted the effectiveness of the microwave non-destructive technique in inspecting the variation of liquid phase morphology of ECCs. The dual-frequency correlation can be used for structural health monitoring, which is not only for prediction but also provides a means of verification. Full article

(This article belongs to the Special Issue Sensor Technologies for Health Monitoring of Composite Structures)

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17 pages, 6559 KiB

Open AccessArticle

The Effect of Electrical Impedance Matching on the Electromechanical Characteristics of Sandwiched Piezoelectric Ultrasonic Transducers

by Yuan Yang, Xiaoyuan Wei^*, Lei Zhang

and Wenqing Yao

Department of Electronic Engineering, Xi’an University of Technology, Xi’an 710048, Shaanxi, China

Sensors 2017, 17(12), 2832; https://doi.org/10.3390/s17122832 - 6 Dec 2017

Cited by 36 | Viewed by 8890

Abstract

For achieving the power maximum transmission, the electrical impedance matching (EIM) for piezoelectric ultrasonic transducers is highly required. In this paper, the effect of EIM networks on the electromechanical characteristics of sandwiched piezoelectric ultrasonic transducers is investigated in time and frequency domains, based [...] Read more.

For achieving the power maximum transmission, the electrical impedance matching (EIM) for piezoelectric ultrasonic transducers is highly required. In this paper, the effect of EIM networks on the electromechanical characteristics of sandwiched piezoelectric ultrasonic transducers is investigated in time and frequency domains, based on the PSpice model of single sandwiched piezoelectric ultrasonic transducer. The above-mentioned EIM networks include, series capacitance and parallel inductance (I type) and series inductance and parallel capacitance (II type). It is shown that when I and II type EIM networks are used, the resonance and anti-resonance frequencies and the received signal tailing are decreased; II type makes the electro-acoustic power ratio and the signal tailing smaller whereas it makes the electro-acoustic gain ratio larger at resonance frequency. In addition, I type makes the effective electromechanical coupling coefficient increase and II type makes it decrease; II type make the power spectral density at resonance frequency more dramatically increased. Specially, the electro-acoustic power ratio has maximum value near anti-resonance frequency, while the electro-acoustic gain ratio has maximum value near resonance frequency. It can be found that the theoretically analyzed results have good consistency with the measured ones. Full article

(This article belongs to the Section Physical Sensors)

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26 pages, 5967 KiB

Open AccessArticle

Sliding Mode Observer-Based Current Sensor Fault Reconstruction and Unknown Load Disturbance Estimation for PMSM Driven System

by Kaihui Zhao¹

, Peng Li¹

, Changfan Zhang¹

, Xiangfei Li¹, Jing He^1,2,* and Yuliang Lin³

¹ College of Electrical and Information Engineering, Hunan University of Technology, Zhuzhou 412007, China

² College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha 410000, China

³ Department of Electrical Engineering, Shandong Polytechnic, Jinan 250104, China

Sensors 2017, 17(12), 2833; https://doi.org/10.3390/s17122833 - 6 Dec 2017

Cited by 38 | Viewed by 5897

Abstract

This paper proposes a new scheme of reconstructing current sensor faults and estimating unknown load disturbance for a permanent magnet synchronous motor (PMSM)-driven system. First, the original PMSM system is transformed into two subsystems; the first subsystem has unknown system load disturbances, which [...] Read more.

This paper proposes a new scheme of reconstructing current sensor faults and estimating unknown load disturbance for a permanent magnet synchronous motor (PMSM)-driven system. First, the original PMSM system is transformed into two subsystems; the first subsystem has unknown system load disturbances, which are unrelated to sensor faults, and the second subsystem has sensor faults, but is free from unknown load disturbances. Introducing a new state variable, the augmented subsystem that has sensor faults can be transformed into having actuator faults. Second, two sliding mode observers (SMOs) are designed: the unknown load disturbance is estimated by the first SMO in the subsystem, which has unknown load disturbance, and the sensor faults can be reconstructed using the second SMO in the augmented subsystem, which has sensor faults. The gains of the proposed SMOs and their stability analysis are developed via the solution of linear matrix inequality (LMI). Finally, the effectiveness of the proposed scheme was verified by simulations and experiments. The results demonstrate that the proposed scheme can reconstruct current sensor faults and estimate unknown load disturbance for the PMSM-driven system. Full article

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

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16 pages, 3789 KiB

Open AccessArticle

Bearing Fault Diagnosis under Variable Speed Using Convolutional Neural Networks and the Stochastic Diagonal Levenberg-Marquardt Algorithm

by Viet Tra, Jaeyoung Kim

, Sheraz Ali Khan

and Jong-Myon Kim^*

School of Electrical, Electronics and Computer Engineering, University of Ulsan, 44610 Ulsan, Korea

Sensors 2017, 17(12), 2834; https://doi.org/10.3390/s17122834 - 6 Dec 2017

Cited by 70 | Viewed by 9274

Abstract

This paper presents a novel method for diagnosing incipient bearing defects under variable operating speeds using convolutional neural networks (CNNs) trained via the stochastic diagonal Levenberg-Marquardt (S-DLM) algorithm. The CNNs utilize the spectral energy maps (SEMs) of the acoustic emission (AE) signals as [...] Read more.

This paper presents a novel method for diagnosing incipient bearing defects under variable operating speeds using convolutional neural networks (CNNs) trained via the stochastic diagonal Levenberg-Marquardt (S-DLM) algorithm. The CNNs utilize the spectral energy maps (SEMs) of the acoustic emission (AE) signals as inputs and automatically learn the optimal features, which yield the best discriminative models for diagnosing incipient bearing defects under variable operating speeds. The SEMs are two-dimensional maps that show the distribution of energy across different bands of the AE spectrum. It is hypothesized that the variation of a bearing’s speed would not alter the overall shape of the AE spectrum rather, it may only scale and translate it. Thus, at different speeds, the same defect would yield SEMs that are scaled and shifted versions of each other. This hypothesis is confirmed by the experimental results, where CNNs trained using the S-DLM algorithm yield significantly better diagnostic performance under variable operating speeds compared to existing methods. In this work, the performance of different training algorithms is also evaluated to select the best training algorithm for the CNNs. The proposed method is used to diagnose both single and compound defects at six different operating speeds. Full article

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

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8 pages, 1932 KiB

Open AccessArticle

A Miniaturized Impedimetric Immunosensor for the Competitive Detection of Adrenocorticotropic Hormone

by Nan Li, Egor M. Larin and Kagan Kerman^*

Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada

Sensors 2017, 17(12), 2836; https://doi.org/10.3390/s17122836 - 7 Dec 2017

Cited by 11 | Viewed by 5009

Abstract

Adrenocorticotropic hormone (ACTH) plays an essential role in regulating corticosteroid hormone production, which has important functions in a myriad of critical physiological functions. In this proof-of-concept study, a miniaturized immunosensor was developed for the highly sensitive detection of ACTH using electrochemical impedance spectroscopy [...] Read more.

Adrenocorticotropic hormone (ACTH) plays an essential role in regulating corticosteroid hormone production, which has important functions in a myriad of critical physiological functions. In this proof-of-concept study, a miniaturized immunosensor was developed for the highly sensitive detection of ACTH using electrochemical impedance spectroscopy (EIS) in connection with disposable screen-printed gold electrodes (SPGEs). A film of 3,3′-dithiobis[sulfosuccinimidylpropionate] (DTSSP) was prepared to immobilize anti-ACTH antibodies covalently on the nanostructured SPGE surface. The surface-immobilized anti-ACTH antibodies captured the biotinylated ACTH (biotin-ACTH) and non-labelled ACTH for the competitive immunoassay. After coupling of a streptavidin-alkaline phosphatase conjugate (Streptavidin-ALP), the bio-catalysed precipitation of an insoluble and insulating product onto the sensing interface changed the charge transfer resistance (R_ct) characteristics significantly. The detection limit of 100 fg/mL was determined for ACTH in a 5 μL sample volume, which indicated that this versatile platform can be easily adapted for miniaturized electrochemical immunosensing of cancer marker biomolecules. High selectivity and sensitivity of our immunoassay to detect ACTH in real samples demonstrated its promising potential for future development and applications using clinical samples. Full article

(This article belongs to the Special Issue Biosensors for Cancer Biomarkers)

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7 pages, 1196 KiB

Open AccessArticle

Two Interrogated FBG Spectral Linewidth for Strain Sensing through Correlation

by Shih-Hsiang Hsu^1,*, Kuo-Wei Chuang¹, Ci-Syu Chen¹, Ching-Yu Lin²

and Che-Chang Chang^3,*

¹ Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan

² School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, 250 Wu-Hsing Street, Taipei 11031, Taiwan

³ Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, 250 Wu-Hsing Street, Taipei 11031, Taiwan

Sensors 2017, 17(12), 2837; https://doi.org/10.3390/s17122837 - 7 Dec 2017

Viewed by 4278

Abstract

The spectral linewidth from two cross-correlated fiber Bragg gratings (FBGs) are interrogated and characterized using a delayed self-homodyne method for fiber strain sensing. This approach employs a common higher frequency resolution instead of wavelength. A sensitivity and resolution of 166 MHz/με and 50 [...] Read more.

The spectral linewidth from two cross-correlated fiber Bragg gratings (FBGs) are interrogated and characterized using a delayed self-homodyne method for fiber strain sensing. This approach employs a common higher frequency resolution instead of wavelength. A sensitivity and resolution of 166 MHz/με and 50 nε were demonstrated from 4 GHz spectral linewidth characterization on the electric spectrum analyzer. A 10 nε higher resolution can be expected through random noise analyses when the spectral linewidth from two FBG correlations is reduced to 1 GHz. Moreover, the FBG spectrum is broadened during strain and experimentally shows a 0.44 pm/με sensitivity, which is mainly caused by the photo elastic effect from the fiber grating period stretch. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2017)

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26 pages, 1412 KiB

Open AccessArticle

Self-Coexistence among IEEE 802.22 Networks: Distributed Allocation of Power and Channel

by Sayef Azad Sakin¹, Md. Abdur Razzaque¹

, Mohammad Mehedi Hassan^2,*

, Atif Alamri²

, Nguyen H. Tran³ and Giancarlo Fortino⁴

¹ Department of Computer Science and Engineering, University of Dhaka, Dhaka 1000, Bangladesh

² College of Computer and Information Sciences, King Saud University, Riyadh 11543, Saudi Arabia

³ Department of Computer Science and Engineering, Kyung Hee University, Gyeonggi-do 17104, Korea

⁴ Department of Informatics, Modeling, Electronics, and Systems, University of Calabria, 87036 Arcavacata, Italy

Sensors 2017, 17(12), 2838; https://doi.org/10.3390/s17122838 - 7 Dec 2017

Cited by 4 | Viewed by 4799

Abstract

Ensuring self-coexistence among IEEE 802.22 networks is a challenging problem owing to opportunistic access of incumbent-free radio resources by users in co-located networks. In this study, we propose a fully-distributed non-cooperative approach to ensure self-coexistence in downlink channels of IEEE 802.22 networks. We [...] Read more.

Ensuring self-coexistence among IEEE 802.22 networks is a challenging problem owing to opportunistic access of incumbent-free radio resources by users in co-located networks. In this study, we propose a fully-distributed non-cooperative approach to ensure self-coexistence in downlink channels of IEEE 802.22 networks. We formulate the self-coexistence problem as a mixed-integer non-linear optimization problem for maximizing the network data rate, which is an NP-hard one. This work explores a sub-optimal solution by dividing the optimization problem into downlink channel allocation and power assignment sub-problems. Considering fairness, quality of service and minimum interference for customer-premises-equipment, we also develop a greedy algorithm for channel allocation and a non-cooperative game-theoretic framework for near-optimal power allocation. The base stations of networks are treated as players in a game, where they try to increase spectrum utilization by controlling power and reaching a Nash equilibrium point. We further develop a utility function for the game to increase the data rate by minimizing the transmission power and, subsequently, the interference from neighboring networks. A theoretical proof of the uniqueness and existence of the Nash equilibrium has been presented. Performance improvements in terms of data-rate with a degree of fairness compared to a cooperative branch-and-bound-based algorithm and a non-cooperative greedy approach have been shown through simulation studies. Full article

(This article belongs to the Collection Smart Communication Protocols and Algorithms for Sensor Networks)

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15 pages, 452 KiB

Open AccessArticle

Link Connectivity and Coverage of Underwater Cognitive Acoustic Networks under Spectrum Constraint

by Qiu Wang¹, Hong-Ning Dai^1,*

, Chak Fong Cheang¹ and Hao Wang²

¹ Faculty of Information Technology, Macau University of Science and Technology, Macau, China

² Norwegian University of Science and Technology, 6009 Aalesund, Norway

Sensors 2017, 17(12), 2839; https://doi.org/10.3390/s17122839 - 7 Dec 2017

Cited by 14 | Viewed by 4111

Abstract

Extensive attention has been given to the use of cognitive radio technology in underwater acoustic networks since the acoustic spectrum became scarce due to the proliferation of human aquatic activities. Most of the recent studies on underwater cognitive acoustic networks (UCANs) mainly focus [...] Read more.

Extensive attention has been given to the use of cognitive radio technology in underwater acoustic networks since the acoustic spectrum became scarce due to the proliferation of human aquatic activities. Most of the recent studies on underwater cognitive acoustic networks (UCANs) mainly focus on spectrum management or protocol design. Few efforts have addressed the quality-of-service (QoS) of UCANs. In UCANs, secondary users (SUs) have lower priority to use acoustic spectrum than primary users (PUs) with higher priority to access spectrum. As a result, the QoS of SUs is difficult to ensure in UCANs. This paper proposes an analytical model to investigate the link connectivity and the probability of coverage of SUs in UCANs. In particular, this model takes both topological connectivity and spectrum availability into account, though spectrum availability has been ignored in most recent studies. We conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Simulation results show that our proposed model is quite accurate. Besides, our results also imply that the link connectivity and the probability of coverage of SUs heavily depend on both the underwater acoustic channel conditions and the activities of PUs. Full article

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

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10 pages, 1903 KiB

Open AccessArticle

Facile Determination of Sodium Ion and Osmolarity in Artificial Tears by Sequential DNAzymes

by Eun Hye Kim^1,2, Eun-Song Lee^1,2, Dong Yun Lee^3,4,*

and Young-Pil Kim^1,2,4,5,*

¹ Department of Life Science, Hanyang University, Seoul 04763, Korea

² Research Institute for Natural Sciences, Hanyang University, Seoul 04763, Korea

³ Department of Bioengineering, Hanyang University, Seoul 04763, Korea

⁴ Institute of Nano Science and Technology, Hanyang University, Seoul 04763, Korea

⁵ Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, Korea

Sensors 2017, 17(12), 2840; https://doi.org/10.3390/s17122840 - 7 Dec 2017

Cited by 8 | Viewed by 5493

Abstract

Despite high relevance of tear osmolarity and eye abnormality, numerous methods for detecting tear osmolarity rely upon expensive osmometers. We report a reliable method for simply determining sodium ion-based osmolarity in artificial tears using sequential DNAzymes. When sodium ion-specific DNAzyme and peroxidase-like DNAzyme [...] Read more.

Despite high relevance of tear osmolarity and eye abnormality, numerous methods for detecting tear osmolarity rely upon expensive osmometers. We report a reliable method for simply determining sodium ion-based osmolarity in artificial tears using sequential DNAzymes. When sodium ion-specific DNAzyme and peroxidase-like DNAzyme were used as a sensing and detecting probe, respectively, the concentration of Na⁺ in artificial tears could be measured by absorbance or fluorescence intensity, which was highly correlated with osmolarity over the diagnostic range (R² > 0.98). Our approach is useful for studying eye diseases in relation to osmolarity. Full article

(This article belongs to the Special Issue Recent Advances in Nucleic Acid Sensors)

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10 pages, 5907 KiB

Open AccessArticle

Recent Enhancements to Interline and Electron Multiplying CCD Image Sensors

by Eric G. Stevens^1,*, Jeffrey A. Clayhold¹, Hung Doan¹, Robert P. Fabinski¹, Jaroslav Hynecek², Stephen L. Kosman¹ and Christopher Parks¹

¹ ON Semiconductor, 1964 Lake Avenue, Rochester, NY 14615, USA

² ON Semiconductor, 2660 Zanker Road, San Jose, CA 95134, USA

Sensors 2017, 17(12), 2841; https://doi.org/10.3390/s17122841 - 7 Dec 2017

Cited by 9 | Viewed by 6035

Abstract

This paper describes recent process modifications made to enhance the performance of interline and electron-multiplying charge-coupled-device (EMCCD) image sensors. By use of MeV ion implantation, quantum efficiency in the NIR region of the spectrum was increased by 2×, and image smear was reduced [...] Read more.

This paper describes recent process modifications made to enhance the performance of interline and electron-multiplying charge-coupled-device (EMCCD) image sensors. By use of MeV ion implantation, quantum efficiency in the NIR region of the spectrum was increased by 2×, and image smear was reduced by 6 dB. By reducing the depth of the shallow photodiode (PD) implants, the photodiode-to-vertical-charge-coupled-device (VCCD) transfer gate voltage required for no-lag operation was reduced by 3 V, and the electronic shutter voltage was reduced by 9 V. The thinner, surface pinning layer also resulted in a reduction of smear by 4 dB in the blue portion of the visible spectrum. For EMCCDs, gain aging was eliminated by providing an oxide-only dielectric under its multiplication phase, while retaining the oxide-nitride-oxide (ONO) gate dielectrics elsewhere in the device. Full article

(This article belongs to the Special Issue Special Issue on the 2017 International Image Sensor Workshop (IISW))

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11 pages, 2324 KiB

Open AccessArticle

High-Speed Focus Inspection System Using a Position-Sensitive Detector

by Binh Xuan Cao^1,2

, Phuong Le Hoang³, Sanghoon Ahn¹, Heeshin Kang¹, Jengo Kim¹ and Jiwhan Noh^1,2,*

¹ Department of Laser and Electron Beam Application, Korea Institute of Machinery & Materials (KIMM), Daejeon 34103, Korea

² Department of Nano-Mechatronics, Korea University of Science and Technology (UST), Daejeon 34113, Korea

³ Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea

Sensors 2017, 17(12), 2842; https://doi.org/10.3390/s17122842 - 8 Dec 2017

Cited by 13 | Viewed by 6293

Abstract

Precise and rapid focus detection is an essential operation in several manufacturing processes employing high-intensity lasers. However, the detection resolution of existing methods is notably low. This paper proposes a technique that provides a rapid-response, high-precision, and high-resolution focus inspection system on the [...] Read more.

Precise and rapid focus detection is an essential operation in several manufacturing processes employing high-intensity lasers. However, the detection resolution of existing methods is notably low. This paper proposes a technique that provides a rapid-response, high-precision, and high-resolution focus inspection system on the basis of geometrical optics and advanced optical instruments. An ultrafast interface position detector and a single-slit mask are used in the system to precisely signal the focus position with high resolution. The reflected images on the image sensor are of a high quality, and this quality is maintained persistently when the target surface is shifted along the optical axis. The proposed system developed for focus inspection is simple and inexpensive, and is appropriate for practical use in the industrial production of sophisticated structures such as microcircuits and microchips. Full article

(This article belongs to the Special Issue Charge-Coupled Device (CCD) Sensors)

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16 pages, 3294 KiB

Open AccessArticle

Novel Noninvasive Brain Disease Detection System Using a Facial Image Sensor

by Ting Shu^†, Bob Zhang^*,† and Yuan Yan Tang

¹ Department of Computer and Information Science, Avenida da Universidade, University of Macau, Taipa, Macau 999078, China

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2843; https://doi.org/10.3390/s17122843 - 8 Dec 2017

Cited by 14 | Viewed by 4825

Abstract

Brain disease including any conditions or disabilities that affect the brain is fast becoming a leading cause of death. The traditional diagnostic methods of brain disease are time-consuming, inconvenient and non-patient friendly. As more and more individuals undergo examinations to determine if they [...] Read more.

Brain disease including any conditions or disabilities that affect the brain is fast becoming a leading cause of death. The traditional diagnostic methods of brain disease are time-consuming, inconvenient and non-patient friendly. As more and more individuals undergo examinations to determine if they suffer from any form of brain disease, developing noninvasive, efficient, and patient friendly detection systems will be beneficial. Therefore, in this paper, we propose a novel noninvasive brain disease detection system based on the analysis of facial colors. The system consists of four components. A facial image is first captured through a specialized sensor, where four facial key blocks are next located automatically from the various facial regions. Color features are extracted from each block to form a feature vector for classification via the Probabilistic Collaborative based Classifier. To thoroughly test the system and its performance, seven facial key block combinations were experimented. The best result was achieved using the second facial key block, where it showed that the Probabilistic Collaborative based Classifier is the most suitable. The overall performance of the proposed system achieves an accuracy −95%, a sensitivity −94.33%, a specificity −95.67%, and an average processing time (for one sample) of <1 min at brain disease detection. Full article

(This article belongs to the Special Issue Sensors for Health Monitoring and Disease Diagnosis)

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9 pages, 2540 KiB

Open AccessArticle

A Wavefront Division Polarimeter for the Measurements of Solute Concentrations in Solutions

by Sergio Calixto^1,*

, Geminiano Martinez-Ponce¹

, Guillermo Garnica¹ and Susana Figueroa-Gerstenmaier²

¹ Centro de Investigaciones en Optica, Loma del Bosque 115, Leon 37150, Mexico

² Departamento de Ingenierias Quimica, Electrónica y Biomedica, Division de Ciencias e Ingenierias, Universidad de Guanajuato Campus Leon, Loma del bosque 103, Leon 37150, Mexico

Sensors 2017, 17(12), 2844; https://doi.org/10.3390/s17122844 - 8 Dec 2017

Cited by 6 | Viewed by 5635

Abstract

Polarimeters are useful instruments that measure concentrations of optically active substances in a given solution. The conventional polarimetric principle consists of measuring the rotation angle of linearly polarized light. Here, we present a novel polarimeter based on the study of interference patterns. A [...] Read more.

Polarimeters are useful instruments that measure concentrations of optically active substances in a given solution. The conventional polarimetric principle consists of measuring the rotation angle of linearly polarized light. Here, we present a novel polarimeter based on the study of interference patterns. A Mach–Zehnder interferometer with linearly polarized light at the input is used. One beam passes through the liquid sample and the other is a reference beam. As the linearly polarized sample beam propagates through the optically active solution the vibration plane of the electric field will rotate. As a result, the visibility of the interference pattern at the interferometer output will decrease. Fringe contrast will be maximum when both beams present a polarization perpendicular to the plane of incidence. However, minimum visibility is obtained when, after propagation through the sample the polarization of the sample beam is oriented parallel to the plane of incidence. By using different solute concentrations, a calibration plot is obtained showing the behavior of visibility. Full article

(This article belongs to the Section Physical Sensors)

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24 pages, 16396 KiB

Open AccessArticle

Chemical Selectivity and Sensitivity of a 16-Channel Electronic Nose for Trace Vapour Detection

by Drago Strle^1,*, Bogdan Štefane²

, Mario Trifkovič¹, Marion Van Miden³, Ivan Kvasić³, Erik Zupanič³ and Igor Muševič^3,4

¹ Faculty of Electrical Engineering, University of Ljubljana, EE dep., Tržaška 25, 1000 Ljubljana, Slovenia

² Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia

³ J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia

⁴ Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia

Sensors 2017, 17(12), 2845; https://doi.org/10.3390/s17122845 - 8 Dec 2017

Cited by 17 | Viewed by 7416

Abstract

Good chemical selectivity of sensors for detecting vapour traces of targeted molecules is vital to reliable detection systems for explosives and other harmful materials. We present the design, construction and measurements of the electronic response of a 16 channel electronic nose based on [...] Read more.

Good chemical selectivity of sensors for detecting vapour traces of targeted molecules is vital to reliable detection systems for explosives and other harmful materials. We present the design, construction and measurements of the electronic response of a 16 channel electronic nose based on 16 differential microcapacitors, which were surface-functionalized by different silanes. The e-nose detects less than 1 molecule of TNT out of 10⁺¹² N₂ molecules in a carrier gas in 1 s. Differently silanized sensors give different responses to different molecules. Electronic responses are presented for TNT, RDX, DNT, H₂S, HCN, FeS, NH₃, propane, methanol, acetone, ethanol, methane, toluene and water. We consider the number density of these molecules and find that silane surfaces show extreme affinity for attracting molecules of TNT, DNT and RDX. The probability to bind these molecules and form a surface-adsorbate is typically 10⁺⁷ times larger than the probability to bind water molecules, for example. We present a matrix of responses of differently functionalized microcapacitors and we propose that chemical selectivity of multichannel e-nose could be enhanced by using artificial intelligence deep learning methods. Full article

(This article belongs to the Special Issue Electronic Tongues and Electronic Noses)

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14 pages, 4282 KiB

Open AccessArticle

Evaluation of Pressure Capacitive Sensors for Application in Grasping and Manipulation Analysis

by Paola Pessia^1,†, Francesca Cordella^1,*,†, Emiliano Schena²

, Angelo Davalli³, Rinaldo Sacchetti³ and Loredana Zollo¹

¹ Unit of Biomedical Robotics and Biomicrosystems, University Campus Bio-Medico of Rome, via Alvaro del Portillo 21, 00128 Rome, Italy

² Unit of Measurements and Biomedical Instrumentation, University Campus Bio-Medico of Rome, via Alvaro del Portillo 21, 00128 Rome, Italy

³ Centro Protesi INAIL, Via Rabuina 14, 40054 Budrio (BO), Italy

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2846; https://doi.org/10.3390/s17122846 - 8 Dec 2017

Cited by 6 | Viewed by 4589

Abstract

The analysis of the human grasping and manipulation capabilities is paramount for investigating human sensory-motor control and developing prosthetic and robotic hands resembling the human ones. A viable solution to perform this analysis is to develop instrumented objects measuring the interaction forces with [...] Read more.

The analysis of the human grasping and manipulation capabilities is paramount for investigating human sensory-motor control and developing prosthetic and robotic hands resembling the human ones. A viable solution to perform this analysis is to develop instrumented objects measuring the interaction forces with the hand. In this context, the performance of the sensors embedded in the objects is crucial. This paper focuses on the experimental characterization of a class of capacitive pressure sensors suitable for biomechanical analysis. The analysis was performed in three loading conditions (Distributed load, 9 Tips load, and Wave-shaped load, thanks to three different inter-elements) via a traction/compression testing machine. Sensor assessment was also carried out under human- like grasping condition by placing a silicon material with the same properties of prosthetic cosmetic gloves in between the sensor and the inter-element in order to simulate the human skin. Data show that the input–output relationship of the analyzed, sensor is strongly influenced by both the loading condition (i.e., type of inter-element) and the grasping condition (with or without the silicon material). This needs to be taken into account to avoid significant measurement error. To go over this hurdle, the sensors have to be calibrated under each specific condition in order to apply suitable corrections to the sensor output and significantly improve the measurement accuracy. Full article

(This article belongs to the Special Issue Force and Pressure Based Sensing Medical Application)

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20 pages, 9330 KiB

Open AccessArticle

Scene Recognition for Indoor Localization Using a Multi-Sensor Fusion Approach

by Mengyun Liu¹

, Ruizhi Chen^1,2,*

, Deren Li^1,2,*, Yujin Chen³

, Guangyi Guo¹, Zhipeng Cao¹ and Yuanjin Pan¹

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

² Collaborative Innovation Center of Geospatial Technology, Wuhan University, Wuhan 430079, China

³ School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China

Sensors 2017, 17(12), 2847; https://doi.org/10.3390/s17122847 - 8 Dec 2017

Cited by 66 | Viewed by 8986

Abstract

After decades of research, there is still no solution for indoor localization like the GNSS (Global Navigation Satellite System) solution for outdoor environments. The major reasons for this phenomenon are the complex spatial topology and RF transmission environment. To deal with these problems, [...] Read more.

After decades of research, there is still no solution for indoor localization like the GNSS (Global Navigation Satellite System) solution for outdoor environments. The major reasons for this phenomenon are the complex spatial topology and RF transmission environment. To deal with these problems, an indoor scene constrained method for localization is proposed in this paper, which is inspired by the visual cognition ability of the human brain and the progress in the computer vision field regarding high-level image understanding. Furthermore, a multi-sensor fusion method is implemented on a commercial smartphone including cameras, WiFi and inertial sensors. Compared to former research, the camera on a smartphone is used to “see” which scene the user is in. With this information, a particle filter algorithm constrained by scene information is adopted to determine the final location. For indoor scene recognition, we take advantage of deep learning that has been proven to be highly effective in the computer vision community. For particle filter, both WiFi and magnetic field signals are used to update the weights of particles. Similar to other fingerprinting localization methods, there are two stages in the proposed system, offline training and online localization. In the offline stage, an indoor scene model is trained by Caffe (one of the most popular open source frameworks for deep learning) and a fingerprint database is constructed by user trajectories in different scenes. To reduce the volume requirement of training data for deep learning, a fine-tuned method is adopted for model training. In the online stage, a camera in a smartphone is used to recognize the initial scene. Then a particle filter algorithm is used to fuse the sensor data and determine the final location. To prove the effectiveness of the proposed method, an Android client and a web server are implemented. The Android client is used to collect data and locate a user. The web server is developed for indoor scene model training and communication with an Android client. To evaluate the performance, comparison experiments are conducted and the results demonstrate that a positioning accuracy of 1.32 m at 95% is achievable with the proposed solution. Both positioning accuracy and robustness are enhanced compared to approaches without scene constraint including commercial products such as IndoorAtlas. Full article

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

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24 pages, 24999 KiB

Open AccessArticle

Thermal Transmission through Existing Building Enclosures: Destructive Monitoring in Intermediate Layers versus Non-Destructive Monitoring with Sensors on Surfaces

by Víctor Echarri^1,*, Almudena Espinosa² and Carlos Rizo¹

¹ Department of Architectural Constructions, University of Alicante, Carretera San Vicente del Raspeig, s/n, 03690 San Vicente del Raspeig, Spain

² Department of Achitecture, University of Zaragoza, Calle María de Luna, 3, 50018 Zaragoza, Spain

Sensors 2017, 17(12), 2848; https://doi.org/10.3390/s17122848 - 8 Dec 2017

Cited by 30 | Viewed by 8062

Abstract

Opaque enclosures of buildings play an essential role in the level of comfort experienced indoors and annual energy demand. The impact of solar radiation and thermal inertia of the materials that make up the multi-layer enclosures substantially modify thermal transmittance behaviour of the [...] Read more.

Opaque enclosures of buildings play an essential role in the level of comfort experienced indoors and annual energy demand. The impact of solar radiation and thermal inertia of the materials that make up the multi-layer enclosures substantially modify thermal transmittance behaviour of the enclosures. This dynamic form of heat transfer, additionally affected by indoor HVAC systems, has a substantial effect on the parameters that define comfort. It also has an impact on energy demand within a daily cycle as well as throughout a one-year use cycle. This study describes the destructive monitoring of an existing block of flats located in Alicante. Once the enclosure was opened, sensors of temperature (PT100), air velocity, and relative humidity were located in the different layers of the enclosure, as well as in the interior and exterior surfaces. A pyranometer was also installed to measure solar radiation levels. A temperature data correction algorithm was drawn up to address irregularities produced in the enclosure. The algorithm was applied using a Raspberry Pi processor in the data collection system. The comparative results of temperature gradients versus non-destructive monitoring systems are presented, providing measures of the transmittance value, surface temperatures and indoor and outdoor air temperatures. This remote sensing system can be used in future studies to quantify and compare the energy savings of different enclosure construction solutions. Full article

(This article belongs to the Special Issue Advances in Sensors for Sustainable Smart Cities and Smart Buildings)

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21 pages, 5539 KiB

Open AccessArticle

Open IoT Ecosystem for Enhanced Interoperability in Smart Cities—Example of Métropole De Lyon

by Jérémy Robert^1,*, Sylvain Kubler^2,3

, Niklas Kolbe¹, Alessandro Cerioni⁴, Emmanuel Gastaud⁴ and Kary Främling⁵

¹ Interdisciplinary Center for Security, Reliability and Trust, University of Luxembourg, 29 Avenue J.F. Kennedy, Luxembourg L-1855, Luxembourg

² Université de Lorraine, CRAN, UMR 7039, 2 Avenue de la forêt de Haye, Vandoeuvre-lès-Nancy CEDEX 54516, France

³ CNRS, CRAN, UMR 7039, France

⁴ Direction de l’Innovation Numérique et Systèmes d’Information, Métropole de Lyon, 20 rue du Lac, CS 33569, 69505 Lyon CEDEX 3, France

⁵ School of Science and Technology, Aalto University, P.O. Box 15500, Aalto 00076, Finland

Sensors 2017, 17(12), 2849; https://doi.org/10.3390/s17122849 - 8 Dec 2017

Cited by 50 | Viewed by 12786

Abstract

The Internet of Things (IoT) has promised a future where everything gets connected. Unfortunately, building a single global ecosystem of Things that communicate with each other seamlessly is virtually impossible today. The reason is that the IoT is essentially a collection of isolated [...] Read more.

The Internet of Things (IoT) has promised a future where everything gets connected. Unfortunately, building a single global ecosystem of Things that communicate with each other seamlessly is virtually impossible today. The reason is that the IoT is essentially a collection of isolated “Intranets of Things”, also referred to as “vertical silos”, which cannot easily and efficiently interact with each other. Smart cities are perhaps the most striking examples of this problem since they comprise a wide range of stakeholders and service providers who must work together, including urban planners, financial organisations, public and private service providers, telecommunication providers, industries, citizens, and so forth. Within this context, the contribution of this paper is threefold: (i) discuss business and technological implications as well as challenges of creating successful open innovation ecosystems, (ii) present the technological building blocks underlying an IoT ecosystem developed in the framework of the EU Horizon 2020 programme, (iii) present a smart city pilot (Heat Wave Mitigation in Métropole de Lyon) for which the proposed ecosystem significantly contributes to improving interoperability between a number of system components, and reducing regulatory barriers for joint service co-creation practices. Full article

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

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14 pages, 4891 KiB

Open AccessArticle

Analysis on Coupled Vibration of a Radially Polarized Piezoelectric Cylindrical Transducer

by Jie Xu, Shuyu Lin^*, Yan Ma and Yifan Tang

Shaanxi Key Laboratory of Ultrasonics, Institute of Applied Acoustics, Shaanxi Normal University, Xi’an 710119, China

Sensors 2017, 17(12), 2850; https://doi.org/10.3390/s17122850 - 8 Dec 2017

Cited by 20 | Viewed by 6617

Abstract

Coupled vibration of a radially polarized piezoelectric cylindrical transducer is analyzed with the mechanical coupling coefficient method. The method has been utilized to analyze the metal cylindrical transducer and the axially polarized piezoelectric cylindrical transducer. In this method, the mechanical coupling coefficient is [...] Read more.

Coupled vibration of a radially polarized piezoelectric cylindrical transducer is analyzed with the mechanical coupling coefficient method. The method has been utilized to analyze the metal cylindrical transducer and the axially polarized piezoelectric cylindrical transducer. In this method, the mechanical coupling coefficient is introduced and defined as the stress ratio in different directions. Coupled vibration of the cylindrical transducer is regarded as the interaction of the plane radial vibration of a ring and the longitudinal vibration of a tube. For the radially polarized piezoelectric cylindrical transducer, the radial and longitudinal electric admittances as functions of mechanical coupling coefficients and angular frequencies are derived, respectively. The resonance frequency equations are obtained. The dependence of resonance frequency and mechanical coupling coefficient on aspect ratio is studied. Vibrational distributions on the surfaces of the cylindrical transducer are presented with experimental measurement. On the support of experiments, this work is verified and provides a theoretical foundation for the analysis and design of the radially polarized piezoelectric cylindrical transducer. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 1967 KiB

Open AccessArticle

Characteristics Study of In-Situ Capacitive Sensor for Monitoring Lubrication Oil Debris

by Zhibin Han, Yishou Wang^* and Xinlin Qing

School of Aerospace Engineering, Xiamen University, Xiamen 361005, China

Sensors 2017, 17(12), 2851; https://doi.org/10.3390/s17122851 - 8 Dec 2017

Cited by 51 | Viewed by 6457

Abstract

As an essential part of engine health monitoring (EHM), online lubrication oil debris monitoring has recently received great attention for the assessment of rotating and reciprocating parts in aero-engines, due to its high integration, low cost and safe characteristics. However, it is be [...] Read more.

As an essential part of engine health monitoring (EHM), online lubrication oil debris monitoring has recently received great attention for the assessment of rotating and reciprocating parts in aero-engines, due to its high integration, low cost and safe characteristics. However, it is be a challenge to find a suitable sensor operating in such a complex environment. We present an unconventional novel approach, in which a cylinder capacitive sensor is designed and integrated with the pipeline of an engine lubrication system, so that the capacitive sensor can effectively detect changes in the lubrication oil condition. In this paper, an attempt to illustrate the performance characteristics of the developed cylinder capacitive sensor is made, through an experiment system that simulates a real scenario of a lubrication oil system. The main aim of the research was to qualitatively describe the relationship between the sensor parameter and the lubrication oil debris. In addition, the effect of the temperature and flow rate of the lubrication oil on capacitance change was performed by several experiments and we figured out a compensation method. The experimental results demonstrated that the cylinder capacitive sensor can potentially be used for lubrication oil debris monitoring of the health condition of an aero-engine. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 1956 KiB

Open AccessArticle

Observing Spring and Fall Phenology in a Deciduous Forest with Aerial Drone Imagery

by Stephen Klosterman^1,* and Andrew D. Richardson^1,2,3

¹ Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA

² School of Informatics, Computing and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA

³ Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA

Sensors 2017, 17(12), 2852; https://doi.org/10.3390/s17122852 - 8 Dec 2017

Cited by 62 | Viewed by 7995

Abstract

Plant phenology is a sensitive indicator of the effects of global change on terrestrial ecosystems and controls the timing of key ecosystem functions including photosynthesis and transpiration. Aerial drone imagery and photogrammetric techniques promise to advance the study of phenology by enabling the [...] Read more.

Plant phenology is a sensitive indicator of the effects of global change on terrestrial ecosystems and controls the timing of key ecosystem functions including photosynthesis and transpiration. Aerial drone imagery and photogrammetric techniques promise to advance the study of phenology by enabling the creation of distortion-free orthomosaics of plant canopies at the landscape scale, but with branch-level image resolution. The main goal of this study is to determine the leaf life cycle events corresponding to phenological metrics derived from automated analyses based on color indices calculated from drone imagery. For an oak-dominated, temperate deciduous forest in the northeastern USA, we find that plant area index (PAI) correlates with a canopy greenness index during spring green-up, and a canopy redness index during autumn senescence. Additionally, greenness and redness metrics are significantly correlated with the timing of budburst and leaf expansion on individual trees in spring. However, we note that the specific color index for individual trees must be carefully chosen if new foliage in spring appears red, rather than green—which we observed for some oak trees. In autumn, both decreasing greenness and increasing redness correlate with leaf senescence. Maximum redness indicates the beginning of leaf fall, and the progression of leaf fall correlates with decreasing redness. We also find that cooler air temperature microclimates near a forest edge bordering a wetland advance the onset of senescence. These results demonstrate the use of drones for characterizing the organismic-level variability of phenology in a forested landscape and advance our understanding of which phenophase transitions correspond to color-based metrics derived from digital image analysis. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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45 pages, 1357 KiB

Open AccessArticle

A Middleware with Comprehensive Quality of Context Support for the Internet of Things Applications

by Berto De Tácio Pereira Gomes^1,2,*,†, Luiz Carlos Melo Muniz^1,†, Francisco José Da Silva e Silva^1,†

, Davi Viana Dos Santos^1,†, Rafael Fernandes Lopes^1,†, Luciano Reis Coutinho^1,†, Felipe Oliveira Carvalho^3,† and Markus Endler^3,†

¹ Programa de Pós-Graduação em Engenharia de Eletricidade (PPGEE), Centro de Ciências Exatas e Tecnologia (CCET), Universidade Federal do Maranhão, 65085-580 São Luís, Brazil

² Instituto Federal do Maranhão (IFMA), Av. dos Curiós, S/N, Vila Esperança, 65095-460 São Luís, Brazil

³ Department of Informatics, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), 22453-900 Rio de Janeiro, Brazil

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2853; https://doi.org/10.3390/s17122853 - 8 Dec 2017

Cited by 21 | Viewed by 6801

Abstract

Context aware systems are able to adapt their behavior according to the environment in which the user is. They can be integrated into an Internet of Things (IoT) infrastructure, allowing a better perception of the user’s physical environment by collecting context data from [...] Read more.

Context aware systems are able to adapt their behavior according to the environment in which the user is. They can be integrated into an Internet of Things (IoT) infrastructure, allowing a better perception of the user’s physical environment by collecting context data from sensors embedded in devices known as smart objects. An IoT extension called the Internet of Mobile Things (IoMT) suggests new scenarios in which smart objects and IoT gateways can move autonomously or be moved easily. In a comprehensive view, Quality of Context (QoC) is a term that can express quality requirements of context aware applications. These requirements can be those related to the quality of information provided by the sensors (e.g., accuracy, resolution, age, validity time) or those referring to the quality of the data distribution service (e.g, reliability, delay, delivery time). Some functionalities of context aware applications and/or decision-making processes of these applications and their users depend on the level of quality of context available, which tend to vary over time for various reasons. Reviewing the literature, it is possible to verify that the quality of context support provided by IoT-oriented middleware systems still has limitations in relation to at least four relevant aspects: (i) quality of context provisioning; (ii) quality of context monitoring; (iii) support for heterogeneous device and technology management; (iv) support for reliable data delivery in mobility scenarios. This paper presents two main contributions: (i) a state-of-the-art survey specifically aimed at analyzing the middleware with quality of context support and; (ii) a new middleware with comprehensive quality of context support for Internet of Things Applications. The proposed middleware was evaluated and the results are presented and discussed in this article, which also shows a case study involving the development of a mobile remote patient monitoring application that was developed using the proposed middleware. This case study highlights how middleware components were used to meet the quality of context requirements of the application. In addition, the proposed middleware was compared to other solutions in the literature. Full article

(This article belongs to the Special Issue Next Generation Wireless Technologies for Internet of Things)

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24 pages, 751 KiB

Open AccessArticle

An Enhanced Privacy-Preserving Authentication Scheme for Vehicle Sensor Networks

by Yousheng Zhou^1,2,3, Xiaofeng Zhao^1,*, Yi Jiang¹, Fengjun Shang¹, Shaojiang Deng^2,* and Xiaojun Wang⁴

¹ College of Computer Science and Technology, Chongqing University of Posts and Telecommunications, Chongqing 400065, China

² College of Computer Science, Chongqing University, Chongqing 400044, China

³ School of Cyber Security and Information Law, Chongqing University of Posts and Telecommunications, Chongqing 400065, China

⁴ School of Electronic Engineering, Dublin City University, Dublin, Ireland

Sensors 2017, 17(12), 2854; https://doi.org/10.3390/s17122854 - 8 Dec 2017

Cited by 28 | Viewed by 5708

Abstract

Vehicle sensor networks (VSNs) are ushering in a promising future by enabling more intelligent transportation systems and providing a more efficient driving experience. However, because of their inherent openness, VSNs are subject to a large number of potential security threats. Although various authentication [...] Read more.

Vehicle sensor networks (VSNs) are ushering in a promising future by enabling more intelligent transportation systems and providing a more efficient driving experience. However, because of their inherent openness, VSNs are subject to a large number of potential security threats. Although various authentication schemes have been proposed for addressing security problems, they are not suitable for VSN applications because of their high computation and communication costs. Chuang and Lee have developed a trust-extended authentication mechanism (TEAM) for vehicle-to-vehicle communication using a transitive trust relationship, which they claim can resist various attacks. However, it fails to counter internal attacks because of the utilization of a shared secret key. In this paper, to eliminate the vulnerability of TEAM, an enhanced privacy-preserving authentication scheme for VSNs is constructed. The security of our proposed scheme is proven under the random oracle model based on the assumption of the computational Diffie–Hellman problem. Full article

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

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14 pages, 6990 KiB

Open AccessArticle

Stacked Sparse Auto-Encoders (SSAE) Based Electronic Nose for Chinese Liquors Classification

by Wei Zhao, Qing-Hao Meng, Ming Zeng^*

and Pei-Feng Qi^*

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

Sensors 2017, 17(12), 2855; https://doi.org/10.3390/s17122855 - 8 Dec 2017

Cited by 34 | Viewed by 5689

Abstract

This paper presents a stacked sparse auto-encoder (SSAE) based deep learning method for an electronic nose (e-nose) system to classify different brands of Chinese liquors. It is well known that preprocessing; feature extraction (generation and reduction) are necessary steps in traditional data-processing methods [...] Read more.

This paper presents a stacked sparse auto-encoder (SSAE) based deep learning method for an electronic nose (e-nose) system to classify different brands of Chinese liquors. It is well known that preprocessing; feature extraction (generation and reduction) are necessary steps in traditional data-processing methods for e-noses. However, these steps are complicated and empirical because there is no uniform rule for choosing appropriate methods from many different options. The main advantage of SSAE is that it can automatically learn features from the original sensor data without the steps of preprocessing and feature extraction; which can greatly simplify data processing procedures for e-noses. To identify different brands of Chinese liquors; an SSAE based multi-layer back propagation neural network (BPNN) is constructed. Seven kinds of strong-flavor Chinese liquors were selected for a self-designed e-nose to test the performance of the proposed method. Experimental results show that the proposed method outperforms the traditional methods. Full article

(This article belongs to the Special Issue Electronic Tongues and Electronic Noses)

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24 pages, 11141 KiB

Open AccessArticle

Smart CEI Moncloa: An IoT-based Platform for People Flow and Environmental Monitoring on a Smart University Campus

by Manuel Alvarez-Campana^*

, Gregorio López

, Enrique Vázquez

, Víctor A. Villagrá

and Julio Berrocal

Departamento de Ingeniería de Sistemas Telemáticos, Universidad Politécnica de Madrid, Avenida Complutense 30, 28040 Madrid, Spain

Sensors 2017, 17(12), 2856; https://doi.org/10.3390/s17122856 - 8 Dec 2017

Cited by 85 | Viewed by 13522

Abstract

Internet of Things platforms for Smart Cities are technologically complex and deploying them at large scale involves high costs and risks. Therefore, pilot schemes that allow validating proof of concepts, experimenting with different technologies and services, and fine-tuning them before migrating them to [...] Read more.

Internet of Things platforms for Smart Cities are technologically complex and deploying them at large scale involves high costs and risks. Therefore, pilot schemes that allow validating proof of concepts, experimenting with different technologies and services, and fine-tuning them before migrating them to actual scenarios, are especially important in this context. The IoT platform deployed across the engineering schools of the Universidad Politécnica de Madrid in the Moncloa Campus of International Excellence represents a good example of a test bench for experimentation with Smart City services. This paper presents the main features of this platform, putting special emphasis on the technological challenges faced and on the solutions adopted, as well as on the functionality, services and potential that the platform offers. Full article

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

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22 pages, 1781 KiB

Open AccessArticle

Hybrid Orientation Based Human Limbs Motion Tracking Method

by Grzegorz Glonek^*,† and Adam Wojciechowski^†

¹ Institute of Information Technology, Faculty of Technical Physics, Information Technology and Applied Mathematics, Lodz University of Technology, 215 Wolczanska street, 90-924 Lodz, Poland

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2857; https://doi.org/10.3390/s17122857 - 9 Dec 2017

Cited by 25 | Viewed by 4359

Abstract

One of the key technologies that lays behind the human–machine interaction and human motion diagnosis is the limbs motion tracking. To make the limbs tracking efficient, it must be able to estimate a precise and unambiguous position of each tracked human joint and [...] Read more.

One of the key technologies that lays behind the human–machine interaction and human motion diagnosis is the limbs motion tracking. To make the limbs tracking efficient, it must be able to estimate a precise and unambiguous position of each tracked human joint and resulting body part pose. In recent years, body pose estimation became very popular and broadly available for home users because of easy access to cheap tracking devices. Their robustness can be improved by different tracking modes data fusion. The paper defines the novel approach—orientation based data fusion—instead of dominating in literature position based approach, for two classes of tracking devices: depth sensors (i.e., Microsoft Kinect) and inertial measurement units (IMU). The detailed analysis of their working characteristics allowed to elaborate a new method that let fuse more precisely limbs orientation data from both devices and compensates their imprecisions. The paper presents the series of performed experiments that verified the method’s accuracy. This novel approach allowed to outperform the precision of position-based joints tracking, the methods dominating in the literature, of up to 18%. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 4642 KiB

Open AccessArticle

Hybrid Signal Processing Technique to Improve the Defect Estimation in Ultrasonic Non-Destructive Testing of Composite Structures

by Kumar Anubhav Tiwari^*

, Renaldas Raisutis and Vykintas Samaitis

Prof. K.Baršauskas Ultrasound Research Institute, Kaunas University of Technology, K. Baršausko St. 59, LT-51423 Kaunas, Lithuania

Sensors 2017, 17(12), 2858; https://doi.org/10.3390/s17122858 - 9 Dec 2017

Cited by 63 | Viewed by 10157

Abstract

This work proposes a novel hybrid signal processing technique to extract information on disbond-type defects from a single B-scan in the process of non-destructive testing (NDT) of glass fiber reinforced plastic (GFRP) material using ultrasonic guided waves (GW). The selected GFRP sample has [...] Read more.

This work proposes a novel hybrid signal processing technique to extract information on disbond-type defects from a single B-scan in the process of non-destructive testing (NDT) of glass fiber reinforced plastic (GFRP) material using ultrasonic guided waves (GW). The selected GFRP sample has been a segment of wind turbine blade, which possessed an aerodynamic shape. Two disbond type defects having diameters of 15 mm and 25 mm were artificially constructed on its trailing edge. The experiment has been performed using the low-frequency ultrasonic system developed at the Ultrasound Institute of Kaunas University of Technology and only one side of the sample was accessed. A special configuration of the transmitting and receiving transducers fixed on a movable panel with a separation distance of 50 mm was proposed for recording the ultrasonic guided wave signals at each one-millimeter step along the scanning distance up to 500 mm. Finally, the hybrid signal processing technique comprising the valuable features of the three most promising signal processing techniques: cross-correlation, wavelet transform, and Hilbert–Huang transform has been applied to the received signals for the extraction of defects information from a single B-scan image. The wavelet transform and cross-correlation techniques have been combined in order to extract the approximated size and location of the defects and measurements of time delays. Thereafter, Hilbert–Huang transform has been applied to the wavelet transformed signal to compare the variation of instantaneous frequencies and instantaneous amplitudes of the defect-free and defective signals. Full article

(This article belongs to the Special Issue Non Destructive Testing and Evaluation of Aerospace Composite Structures)

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12 pages, 1692 KiB

Open AccessArticle

A New Laccase Based Biosensor for Tartrazine

by Siti Zulaikha Mazlan¹, Yook Heng Lee¹ and Sharina Abu Hanifah^1,2,*

¹ School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor 43600, Malaysia

² Polymer Research Center, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor 43600, Malaysia

Sensors 2017, 17(12), 2859; https://doi.org/10.3390/s17122859 - 9 Dec 2017

Cited by 32 | Viewed by 6291

Abstract

Laccase enzyme, a commonly used enzyme for the construction of biosensors for phenolic compounds was used for the first time to develop a new biosensor for the determination of the azo-dye tartrazine. The electrochemical biosensor was based on the immobilization of laccase on [...] Read more.

Laccase enzyme, a commonly used enzyme for the construction of biosensors for phenolic compounds was used for the first time to develop a new biosensor for the determination of the azo-dye tartrazine. The electrochemical biosensor was based on the immobilization of laccase on functionalized methacrylate-acrylate microspheres. The biosensor membrane is a composite of the laccase conjugated microspheres and gold nanoparticles (AuNPs) coated on a carbon-paste screen-printed electrode. The reaction involving tartrazine can be catalyzed by laccase enzyme, where the current change was measured by differential pulse voltammetry (DPV) at 1.1 V. The anodic peak current was linear within the tartrazine concentration range of 0.2 to 14 μM (R² = 0.979) and the detection limit was 0.04 μM. Common food ingredients or additives such as glucose, sucrose, ascorbic acid, phenol and sunset yellow did not interfere with the biosensor response. Furthermore, the biosensor response was stable up to 30 days of storage period at 4 °C. Foods and beverage were used as real samples for the biosensor validation. The biosensor response to tartrazine showed no significant difference with a standard HPLC method for tartrazine analysis. Full article

(This article belongs to the Special Issue Development of Enzymatic Electrochemical Biosensors and Applications)

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11 pages, 7381 KiB

Open AccessArticle

Development of Gentle Slope Light Guide Structure in a 3.4 μm Pixel Pitch Global Shutter CMOS Image Sensor with Multiple Accumulation Shutter Technology

by Hiroshi Sekine^*

, Masahiro Kobayashi

, Yusuke Onuki, Kazunari Kawabata, Toshiki Tsuboi, Yasushi Matsuno, Hidekazu Takahashi, Shunsuke Inoue and Takeshi Ichikawa

Canon Inc., 70-1, Yanagi-cho, Saiwai-ku, Kawasaki-shi, Kanagawa 212-8602, Japan

Sensors 2017, 17(12), 2860; https://doi.org/10.3390/s17122860 - 9 Dec 2017

Cited by 5 | Viewed by 9977

Abstract

CMOS image sensors (CISs) with global shutter (GS) function are strongly required in order to avoid image degradation. However, CISs with GS function have generally been inferior to the rolling shutter (RS) CIS in performance, because they have more components. This problem is [...] Read more.

CMOS image sensors (CISs) with global shutter (GS) function are strongly required in order to avoid image degradation. However, CISs with GS function have generally been inferior to the rolling shutter (RS) CIS in performance, because they have more components. This problem is remarkable in small pixel pitch. The newly developed 3.4 µm pitch GS CIS solves this problem by using multiple accumulation shutter technology and the gentle slope light guide structure. As a result, the developed GS pixel achieves 1.8 e⁻ temporal noise and 16,200 e⁻ full well capacity with charge domain memory in 120 fps operation. The sensitivity and parasitic light sensitivity are 28,000 e⁻/lx·s and −89 dB, respectively. Moreover, the incident light angle dependence of sensitivity and parasitic light sensitivity are improved by the gentle slope light guide structure. Full article

(This article belongs to the Special Issue Special Issue on the 2017 International Image Sensor Workshop (IISW))

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12 pages, 1190 KiB

Open AccessArticle

Iterative Refinement of Transmission Map for Stereo Image Defogging Using a Dual Camera Sensor

by Heegwang Kim

, Jinho Park

, Hasil Park and Joonki Paik^*

Department of Image, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Korea

Sensors 2017, 17(12), 2861; https://doi.org/10.3390/s17122861 - 9 Dec 2017

Cited by 5 | Viewed by 5204

Abstract

Recently, the stereo imaging-based image enhancement approach has attracted increasing attention in the field of video analysis. This paper presents a dual camera-based stereo image defogging algorithm. Optical flow is first estimated from the stereo foggy image pair, and the initial disparity map [...] Read more.

Recently, the stereo imaging-based image enhancement approach has attracted increasing attention in the field of video analysis. This paper presents a dual camera-based stereo image defogging algorithm. Optical flow is first estimated from the stereo foggy image pair, and the initial disparity map is generated from the estimated optical flow. Next, an initial transmission map is generated using the initial disparity map. Atmospheric light is then estimated using the color line theory. The defogged result is finally reconstructed using the estimated transmission map and atmospheric light. The proposed method can refine the transmission map iteratively. Experimental results show that the proposed method can successfully remove fog without color distortion. The proposed method can be used as a pre-processing step for an outdoor video analysis system and a high-end smartphone with a dual camera system. Full article

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

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11 pages, 3699 KiB

Open AccessArticle

Two-Channel SPR Sensor Combined Application of Polymer- and Vitreous-Clad Optic Fibers

by Yong Wei^1,2, Yudong Su², Chunlan Liu³, Xiangfei Nie², Zhihai Liu⁴, Yu Zhang⁴ and Yonghui Zhang^5,*

¹ Key Laboratory of Intelligent Information Processing and Control, Chongqing Three Gorges University, Wanzhou, Chongqing 404100, China

² College of Electronic ＆ Information Engineering, Chongqing Three Gorges University, Chongqing 404100, China

³ Chongqing Engineering Research Center of Internet of Things and Intelligent Control Technology, Chongqing Three Gorges University, Chongqing 404100, China

⁴ Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China

⁵ Basic Medicine Department, Chongqing Three Gorges Medical College, Chongqing 404100, China

Sensors 2017, 17(12), 2862; https://doi.org/10.3390/s17122862 - 9 Dec 2017

Cited by 15 | Viewed by 5088

Abstract

By combining a polymer-clad optic fiber and a vitreous-clad optic fiber, we proposed and fabricated a novel optic fiber surface plasmon resonance (SPR) sensor to conduct two-channel sensing at the same detection area. The traditional optic fiber SPR sensor has many disadvantages; for [...] Read more.

By combining a polymer-clad optic fiber and a vitreous-clad optic fiber, we proposed and fabricated a novel optic fiber surface plasmon resonance (SPR) sensor to conduct two-channel sensing at the same detection area. The traditional optic fiber SPR sensor has many disadvantages; for example, removing the cladding requires corrosion, operating it is dangerous, adjusting the dynamic response range is hard, and producing different resonance wavelengths in the sensing area to realize a multi-channel measurement is difficult. Therefore, in this paper, we skillfully used bare fiber grinding technology and reverse symmetry welding technology to remove the cladding in a multi-mode fiber and expose the evanescent field. On the basis of investigating the effect of the grinding angle on the dynamic range change of the SPR resonance valley wavelength and sensitivity, we combined polymer-clad fiber and vitreous-clad fiber by a smart design structure to realize at a single point a two-channel measurement fiber SPR sensor. In this paper, we obtained a beautiful spectral curve from a multi-mode fiber two-channel SPR sensor. In the detection range of the refractive rate between 1.333 RIU and 1.385 RIU, the resonance valley wavelength of channel Ⅰ shifted from 622 nm to 724 nm with a mean average sensitivity of 1961 nm/RIU and the resonance valley wavelength of channel Ⅱ shifted from 741 nm to 976 nm with a mean average sensitivity of 4519 nm/RIU. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 4438 KiB

Open AccessArticle

An AST-ELM Method for Eliminating the Influence of Charging Phenomenon on ECT

by Xiaoxin Wang^1,*, Hongli Hu², Huiqin Jia¹ and Kaihao Tang²

¹ Key Laboratory of Education Ministry for Photoelectric Logging and Detecting of Oil and Gas, Xi’an Shiyou University, Xi’an 710065, China

² State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(12), 2863; https://doi.org/10.3390/s17122863 - 9 Dec 2017

Cited by 5 | Viewed by 3866

Abstract

Electrical capacitance tomography (ECT) is a promising imaging technology of permittivity distributions in multiphase flow. To reduce the effect of charging phenomenon on ECT measurement, an improved extreme learning machine method combined with adaptive soft-thresholding (AST-ELM) is presented and studied for image reconstruction. [...] Read more.

Electrical capacitance tomography (ECT) is a promising imaging technology of permittivity distributions in multiphase flow. To reduce the effect of charging phenomenon on ECT measurement, an improved extreme learning machine method combined with adaptive soft-thresholding (AST-ELM) is presented and studied for image reconstruction. This method can provide a nonlinear mapping model between the capacitance values and medium distributions by using machine learning but not an electromagnetic-sensitive mechanism. Both simulation and experimental tests are carried out to validate the performance of the presented method, and reconstructed images are evaluated by relative error and correlation coefficient. The results have illustrated that the image reconstruction accuracy by the proposed AST-ELM method has greatly improved than that by the conventional methods under the condition with charging object. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 5930 KiB

Open AccessArticle

Home Camera-Based Fall Detection System for the Elderly

by Koldo De Miguel^†, Alberto Brunete^*,†

, Miguel Hernando^†

and Ernesto Gambao^†

¹ Centre for Automation and Robotics (CAR UPM-CSIC), Universidad Politécnica de Madrid, Madrid, Spain

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2864; https://doi.org/10.3390/s17122864 - 9 Dec 2017

Cited by 223 | Viewed by 18831

Abstract

Falls are the leading cause of injury and death in elderly individuals. Unfortunately, fall detectors are typically based on wearable devices, and the elderly often forget to wear them. In addition, fall detectors based on artificial vision are not yet available on the [...] Read more.

Falls are the leading cause of injury and death in elderly individuals. Unfortunately, fall detectors are typically based on wearable devices, and the elderly often forget to wear them. In addition, fall detectors based on artificial vision are not yet available on the market. In this paper, we present a new low-cost fall detector for smart homes based on artificial vision algorithms. Our detector combines several algorithms (background subtraction, Kalman filtering and optical flow) as input to a machine learning algorithm with high detection accuracy. Tests conducted on over 50 different fall videos have shown a detection ratio of greater than 96%. Full article

(This article belongs to the Special Issue Context Aware Environments and Applications)

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17 pages, 3106 KiB

Open AccessArticle

Markov Chain Realization of Joint Integrated Probabilistic Data Association

by Eui Hyuk Lee¹, Qian Zhang² and Taek Lyul Song^2,*

¹ 5th Development Division, Agency for Defense Development, P.O.Box 35, Daejeon, Korea

² Department of Electronic Systems Engineering, Hanyang University, Ansan, 15588, Korea

Sensors 2017, 17(12), 2865; https://doi.org/10.3390/s17122865 - 10 Dec 2017

Cited by 13 | Viewed by 3713

Abstract

A practical probabilistic data association filter is proposed for tracking multiple targets in clutter. The number of joint data association events increases combinatorially with the number of measurements and the number of targets, which may become computationally impractical for even small numbers of [...] Read more.

A practical probabilistic data association filter is proposed for tracking multiple targets in clutter. The number of joint data association events increases combinatorially with the number of measurements and the number of targets, which may become computationally impractical for even small numbers of closely located targets in real target-tracking applications in heavily cluttered environments. In this paper, a Markov chain model is proposed to generate a set of feasible joint events (FJEs) for multiple target tracking that is used to approximate the multi-target data association probabilities and the probabilities of target existence of joint integrated probabilistic data association (JIPDA). A Markov chain with the transition probabilities obtained from the integrated probabilistic data association (IPDA) for single-target tracking is designed to generate a random sequence composed of the predetermined number of FJEs without incurring additional computational cost. The FJEs generated are adjusted for the multi-target tracking environment. A computationally tractable set of these random sequences is utilized to evaluate the track-to-measurement association probabilities such that the computational burden is substantially reduced compared to the JIPDA algorithm. By a series of simulations, the track confirmation rates and target retention statistics of the proposed algorithm are compared with the other existing algorithms including JIPDA to show the effectiveness of the proposed algorithm. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 3844 KiB

Open AccessArticle

Position Tracking During Human Walking Using an Integrated Wearable Sensing System

by Giulio Zizzo^† and Lei Ren^*

¹ School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester M13 9PL, UK

^† Current address: Imperial College London, London SW7 2AZ, UK.

Sensors 2017, 17(12), 2866; https://doi.org/10.3390/s17122866 - 10 Dec 2017

Cited by 31 | Viewed by 6913

Abstract

Progress has been made enabling expensive, high-end inertial measurement units (IMUs) to be used as tracking sensors. However, the cost of these IMUs is prohibitive to their widespread use, and hence the potential of low-cost IMUs is investigated in this study. A wearable [...] Read more.

Progress has been made enabling expensive, high-end inertial measurement units (IMUs) to be used as tracking sensors. However, the cost of these IMUs is prohibitive to their widespread use, and hence the potential of low-cost IMUs is investigated in this study. A wearable low-cost sensing system consisting of IMUs and ultrasound sensors was developed. Core to this system is an extended Kalman filter (EKF), which provides both zero-velocity updates (ZUPTs) and Heuristic Drift Reduction (HDR). The IMU data was combined with ultrasound range measurements to improve accuracy. When a map of the environment was available, a particle filter was used to impose constraints on the possible user motions. The system was therefore composed of three subsystems: IMUs, ultrasound sensors, and a particle filter. A Vicon motion capture system was used to provide ground truth information, enabling validation of the sensing system. Using only the IMU, the system showed loop misclosure errors of 1% with a maximum error of 4–5% during walking. The addition of the ultrasound sensors resulted in a 15% reduction in the total accumulated error. Lastly, the particle filter was capable of providing noticeable corrections, which could keep the tracking error below 2% after the first few steps. Full article

(This article belongs to the Special Issue Wearable and Ambient Sensors for Healthcare and Wellness Applications 2018)

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10 pages, 5441 KiB

Open AccessArticle

Thin-Film Quantum Dot Photodiode for Monolithic Infrared Image Sensors

by Pawel E. Malinowski^1,*

, Epimitheas Georgitzikis^1,2, Jorick Maes^3,4

, Ioanna Vamvaka^1,2, Fortunato Frazzica^1,5, Jan Van Olmen¹, Piet De Moor¹, Paul Heremans^1,2, Zeger Hens^3,4 and David Cheyns¹

¹ IMEC, Kapeldreef 75, B-3001 Leuven, Belgium

² KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium

³ Physics and Chemistry of Nanostructures, Ghent University, Krijgslaan 281-S3, B-9000 Ghent, Belgium

⁴ Center for Nano- and Biophotonics (NB-Photonics), Ghent University, B-9000 Ghent, Belgium

⁵ Vrije Universiteit Brussel (VUB–ETRO), Pleinlaan 2, B-1050 Brussel, Belgium

Sensors 2017, 17(12), 2867; https://doi.org/10.3390/s17122867 - 10 Dec 2017

Cited by 48 | Viewed by 16323

Abstract

Imaging in the infrared wavelength range has been fundamental in scientific, military and surveillance applications. Currently, it is a crucial enabler of new industries such as autonomous mobility (for obstacle detection), augmented reality (for eye tracking) and biometrics. Ubiquitous deployment of infrared cameras [...] Read more.

Imaging in the infrared wavelength range has been fundamental in scientific, military and surveillance applications. Currently, it is a crucial enabler of new industries such as autonomous mobility (for obstacle detection), augmented reality (for eye tracking) and biometrics. Ubiquitous deployment of infrared cameras (on a scale similar to visible cameras) is however prevented by high manufacturing cost and low resolution related to the need of using image sensors based on flip-chip hybridization. One way to enable monolithic integration is by replacing expensive, small-scale III–V-based detector chips with narrow bandgap thin-films compatible with 8- and 12-inch full-wafer processing. This work describes a CMOS-compatible pixel stack based on lead sulfide quantum dots (PbS QD) with tunable absorption peak. Photodiode with a 150-nm thick absorber in an inverted architecture shows dark current of 10⁻⁶ A/cm² at −2 V reverse bias and EQE above 20% at 1440 nm wavelength. Optical modeling for top illumination architecture can improve the contact transparency to 70%. Additional cooling (193 K) can improve the sensitivity to 60 dB. This stack can be integrated on a CMOS ROIC, enabling order-of-magnitude cost reduction for infrared sensors. Full article

(This article belongs to the Special Issue Special Issue on the 2017 International Image Sensor Workshop (IISW))

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12 pages, 1333 KiB

Open AccessArticle

Signal Subspace Smoothing Technique for Time Delay Estimation Using MUSIC Algorithm

by Meng Sun¹, Yide Wang²

, Cédric Le Bastard^2,3, Jingjing Pan² and Yuehua Ding^4,*

¹ Information Engineering College, Shanghai Maritime University, Shanghai 201306, China

² Institut d’Electronique et Télécommunications de Rennes, UMR CNRS 6164, Université de Nantes, 44306 Nantes CEDEX 3, France

³ Cerema, Project-Team ENSUM, 49136 Les Ponts de Cé, France

⁴ School of Electronic and Information Engineering, South China University of Technology, Wushan Road, Tianhe District, Guangzhou 510641, China

Sensors 2017, 17(12), 2868; https://doi.org/10.3390/s17122868 - 10 Dec 2017

Cited by 7 | Viewed by 4665

Abstract

In civil engineering, Time Delay Estimation (TDE) is one of the most important tasks for the media structure and quality evaluation. In this paper, the MUSIC algorithm is applied to estimate the time delay. In practice, the backscattered echoes are highly correlated (even [...] Read more.

In civil engineering, Time Delay Estimation (TDE) is one of the most important tasks for the media structure and quality evaluation. In this paper, the MUSIC algorithm is applied to estimate the time delay. In practice, the backscattered echoes are highly correlated (even coherent). In order to apply the MUSIC algorithm, an adaptation of signal subspace smoothing is proposed to decorrelate the correlation between echoes. Unlike the conventional sub-band averaging techniques, we propose to directly use the signal subspace, which can take full advantage of the signal subspace and reduce the influence of noise. Moreover, the proposed method is adapted to deal with any radar pulse shape. The proposed method is tested on both numerical and experimental data. Both results show the effectiveness of the proposed method. Full article

(This article belongs to the Section Remote Sensors)

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17 pages, 2262 KiB

Open AccessArticle

A Practical, Robust and Fast Method for Location Localization in Range-Based Systems

by Shiping Huang^1,2, Zhifeng Wu³ and Anil Misra^4,*

¹ State Key Lab of Subtropical Building Science, South China University of Technology, Guangzhou 510640, China

² State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Xuzhou 221116, China

³ School of Information, Guangdong Communication Polytechnic, Guangzhou 510650, China

⁴ Civil, Environmental and Architectural Engineering, The University of Kansas, Lawrence, KS 66045, USA

Sensors 2017, 17(12), 2869; https://doi.org/10.3390/s17122869 - 11 Dec 2017

Cited by 12 | Viewed by 3305

Abstract

Location localization technology is used in a number of industrial and civil applications. Real time location localization accuracy is highly dependent on the quality of the distance measurements and efficiency of solving the localization equations. In this paper, we provide a novel approach [...] Read more.

Location localization technology is used in a number of industrial and civil applications. Real time location localization accuracy is highly dependent on the quality of the distance measurements and efficiency of solving the localization equations. In this paper, we provide a novel approach to solve the nonlinear localization equations efficiently and simultaneously eliminate the bad measurement data in range-based systems. A geometric intersection model was developed to narrow the target search area, where Newton’s Method and the Direct Search Method are used to search for the unknown position. Not only does the geometric intersection model offer a small bounded search domain for Newton’s Method and the Direct Search Method, but also it can self-correct bad measurement data. The Direct Search Method is useful for the coarse localization or small target search domain, while the Newton’s Method can be used for accurate localization. For accurate localization, by utilizing the proposed Modified Newton’s Method (MNM), challenges of avoiding the local extrema, singularities, and initial value choice are addressed. The applicability and robustness of the developed method has been demonstrated by experiments with an indoor system. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 5787 KiB

Open AccessArticle

A Dual-Butterfly Structure Gyroscope

by Xiangming Xu, Dingbang Xiao^*, Wenyin Li, Qiang Xu, Zhanqiang Hou and Xuezhong Wu

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

Sensors 2017, 17(12), 2870; https://doi.org/10.3390/s17122870 - 11 Dec 2017

Cited by 6 | Viewed by 4784

Abstract

This paper reports a dual-butterfly structure gyroscope based on the traditional butterfly structure. This novel structure is composed of two butterfly structures, each of which contains a main vibrational beam, four proof masses, and a coupling mechanism. The coupling mechanism in this proposed [...] Read more.

This paper reports a dual-butterfly structure gyroscope based on the traditional butterfly structure. This novel structure is composed of two butterfly structures, each of which contains a main vibrational beam, four proof masses, and a coupling mechanism. The coupling mechanism in this proposed structure couples the two single butterfly structures and keeps the driving mode phases of the two single butterfly gyroscopes exactly opposite, increasing the double difference of traditional butterfly gyroscopes to a quad difference, which has the potential advantage of improving bias instability and g-sensitivity. The gyroscope was fabricated using a standard microfabrication method and tested in laboratory conditions. The experimental results show a Q-factor of 10,967 in driving mode and there were two peaks in the frequency responses curve of sensing direction due to unavoidable fabrication errors. Scale factor and bias instability were also measured, reaching a scale factor of 10.9 mV/°/s and a bias instability of 10.7°/h, according to the Allan Variance curve. Full article

(This article belongs to the Section Physical Sensors)

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13 pages, 4845 KiB

Open AccessArticle

A Novel Passive Wireless Sensing Method for Concrete Chloride Ion Concentration Monitoring

by Shuangxi Zhou¹, Wei Sheng¹, Fangming Deng^2,*, Xiang Wu² and Zhihui Fu²

¹ School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China

² School of Electrical and Automation Engineering, East China Jiaotong University, Nanchang 330013, China

Sensors 2017, 17(12), 2871; https://doi.org/10.3390/s17122871 - 11 Dec 2017

Cited by 20 | Viewed by 5559

Abstract

In this paper, a novel approach for concrete chloride ion concentration measuring based on passive and wireless sensor tag is proposed. The chloride ion sensor based on RFID communication protocol is consisting of an energy harvesting and management circuit, a low dropout voltage [...] Read more.

In this paper, a novel approach for concrete chloride ion concentration measuring based on passive and wireless sensor tag is proposed. The chloride ion sensor based on RFID communication protocol is consisting of an energy harvesting and management circuit, a low dropout voltage regulator, a MCU, a RFID tag chip and a pair of electrodes. The proposed sensor harvests energy radiated by the RFID reader to power its circuitry. To improve the stability of power supply, a three-stage boost rectifier is customized to rectify the harvested power into dc power and step-up the voltage. Since the measured data is wirelessly transmitted, it contains miscellaneous noises which would decrease the accuracy of measuring. Thus, in this paper, the wavelet denoising method is adopted to denoise the raw data. Besides, a monitoring software is developed to display the measurement results in real-time. The measurement results indicate that the proposed passive sensor tag can achieve a reliable communication distance of 16.3 m and can reliably measure the chloride ion concentration in concrete. Full article

(This article belongs to the Special Issue RFID-Based Sensors for IoT Applications)

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18 pages, 10466 KiB

Open AccessArticle

An Approach for the Dynamic Measurement of Ring Gear Strains of Planetary Gearboxes Using Fiber Bragg Gratings

by Hang Niu¹

, Xiaodong Zhang^1,2 and Chenggang Hou^1,*

¹ School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China

² Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Xi’an Jiaotong University, Xi’an 710049, China

Sensors 2017, 17(12), 2872; https://doi.org/10.3390/s17122872 - 16 Dec 2017

Cited by 15 | Viewed by 4807

Abstract

The strain of the ring gear can reflect the dynamic characteristics of planetary gearboxes directly, which makes it an ideal signal to monitor the health condition of the gearbox. To overcome the disadvantages of traditional methods, a new approach for the dynamic measurement [...] Read more.

The strain of the ring gear can reflect the dynamic characteristics of planetary gearboxes directly, which makes it an ideal signal to monitor the health condition of the gearbox. To overcome the disadvantages of traditional methods, a new approach for the dynamic measurement of ring gear strains using fiber Bragg gratings (FBGs) is proposed in this paper. Firstly, the installation of FBGs is determined according to the analysis for the strain distribution of the ring gear. Secondly, the parameters of the FBG are determined in consideration of the accuracy and sensitivity of the measurement as well as the size of the ring gear. The strain measured by the FBG is then simulated under non-uniform strain field conditions. Thirdly, a dynamic measurement system is built and tested. Finally, the strains of the ring gear are measured in a planetary gearbox under normal and faulty conditions. The experimental results showed good agreement with the theoretical results in values, trends, and the fault features can be seen from the time domain of the measured strain signal, which proves that the proposed method is feasible for the measurement of the ring gear strains of planetary gearboxes. Full article

(This article belongs to the Special Issue Fiber Bragg Grating Based Sensors)

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17 pages, 4844 KiB

Open AccessArticle

Calibration of Binocular Vision Sensors Based on Unknown-Sized Elliptical Stripe Images

by Zhen Liu¹, Suining Wu¹, Yang Yin¹ and Jinbo Wu^2,3,*

¹ Key Laboratory of Precision Opto-mechatronics Technology, Ministry of Education, Beihang University, No. 37 Xueyuan Road, Haidian District, Beijing 100191, China

² School of Naval Architecture & Ocean Engineering, Huazhong University of Science & Technology, 1037 Luoyu Road, Wuhan 430074, China

³ Hubei Key Laboratory of Naval Architecture & Ocean Engineering Hydrodynamics (HUST), Huazhong University of Science & Technology, Wuhan 430074, China

Sensors 2017, 17(12), 2873; https://doi.org/10.3390/s17122873 - 13 Dec 2017

Cited by 9 | Viewed by 4194

Abstract

Most of the existing calibration methods for binocular stereo vision sensor (BSVS) depend on a high-accuracy target with feature points that are difficult and costly to manufacture and. In complex light conditions, optical filters are used for BSVS, but they affect imaging quality. [...] Read more.

Most of the existing calibration methods for binocular stereo vision sensor (BSVS) depend on a high-accuracy target with feature points that are difficult and costly to manufacture and. In complex light conditions, optical filters are used for BSVS, but they affect imaging quality. Hence, the use of a high-accuracy target with certain-sized feature points for calibration is not feasible under such complex conditions. To solve these problems, a calibration method based on unknown-sized elliptical stripe images is proposed. With known intrinsic parameters, the proposed method adopts the elliptical stripes located on the parallel planes as a medium to calibrate BSVS online. In comparison with the common calibration methods, the proposed method avoids utilizing high-accuracy target with certain-sized feature points. Therefore, the proposed method is not only easy to implement but is a realistic method for the calibration of BSVS with optical filter. Changing the size of elliptical curves projected on the target solves the difficulty of applying the proposed method in different fields of view and distances. Simulative and physical experiments are conducted to validate the efficiency of the proposed method. When the field of view is approximately 400 mm × 300 mm, the proposed method can reach a calibration accuracy of 0.03 mm, which is comparable with that of Zhang’s method. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 546 KiB

Open AccessArticle

A Game-Theory Based Incentive Framework for an Intelligent Traffic System as Part of a Smart City Initiative

by Haibo Mei^1,*,†,‡, Stefan Poslad^2,‡ and Shuang Du¹

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

² School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, UK

^† Current address: No.2006, Xiyuan Ave, West Hi-Tech Zone, Chengdu 611731, China.

^‡ These authors contributed equally to this work.

Sensors 2017, 17(12), 2874; https://doi.org/10.3390/s17122874 - 11 Dec 2017

Cited by 24 | Viewed by 7156

Abstract

Intelligent Transportation Systems (ITSs) can be applied to inform and incentivize travellers to help them make cognizant choices concerning their trip routes and transport modality use for their daily travel whilst achieving more sustainable societal and transport authority goals. However, in practice, it [...] Read more.

Intelligent Transportation Systems (ITSs) can be applied to inform and incentivize travellers to help them make cognizant choices concerning their trip routes and transport modality use for their daily travel whilst achieving more sustainable societal and transport authority goals. However, in practice, it is challenging for an ITS to enable incentive generation that is context-driven and personalized, whilst supporting multi-dimensional travel goals. This is because an ITS has to address the situation where different travellers have different travel preferences and constraints for route and modality, in the face of dynamically-varying traffic conditions. Furthermore, personalized incentive generation also needs to dynamically achieve different travel goals from multiple travellers, in the face of their conducts being a mix of both competitive and cooperative behaviours. To address this challenge, a Rule-based Incentive Framework (RIF) is proposed in this paper that utilizes both decision tree and evolutionary game theory to process travel information and intelligently generate personalized incentives for travellers. The travel information processed includes travellers’ mobile patterns, travellers’ modality preferences and route traffic volume information. A series of MATLAB simulations of RIF was undertaken to validate RIF to show that it is potentially an effective way to incentivize travellers to change travel routes and modalities as an essential smart city service. Full article

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

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25 pages, 2871 KiB

Open AccessArticle

Performance Analysis of a Novel Hybrid S-ALOHA/TDMA Protocol for Beta Distributed Massive MTC Access

by Nannan Sui¹, Youyun Xu², Cong Wang^1,*

and Wei Xie¹

¹ College of Communications Engineering, Army Engineering University of PLA, Nanjing 210007, China

² National Engineering Research Center of Communication and Network Technologies, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

Sensors 2017, 17(12), 2875; https://doi.org/10.3390/s17122875 - 15 Dec 2017

Cited by 3 | Viewed by 4819

Abstract

Simultaneous random access of massive machine type communications (MTC) devices are expected to cause congestion in the radio access network. Not only the performance of MTC, but the coexisting human to human (H2H) communications would also degrade dramatically without an appropriate medium access [...] Read more.

Simultaneous random access of massive machine type communications (MTC) devices are expected to cause congestion in the radio access network. Not only the performance of MTC, but the coexisting human to human (H2H) communications would also degrade dramatically without an appropriate medium access control (MAC) protocol. However, most existing solutions focus on the random access procedure without dealing with the sunsequent data transmission procedure. In this paper, we firstly derive a packet size threshold based on the capacity analysis of slotted ALOHA (S-ALOHA) and time division multiple access (TDMA) protocols. Then a novel hybrid S-ALOHA/TDMA MAC protocol (HSTMAC) is presented for massive MTC access, in which the resources are separated for beta distributed machine to machine (M2M) traffic with small size packets and high priority H2H traffic with large size packets. Considering access class barring (ACB) scheme as an overload control method, the system equilibrium under arbitrary retransmission limit is analyzed rigorously, which can provide insights on quality of service (QoS) guarantee. Finally, a dynamic pre-backoff (DPBO) algorithm is designed for load balance by adaptively scattering the highly synchronized M2M traffic over the transmission interval. Numerical and simulation results validate our analysis and show that the HSTMAC protocol is superior to pure S-ALOHA protocol and pure TDMA protocol. The proposed DPBO algorithm can achieve a higher success probability and resource utilization ratio with a much reduced average delay than that of uniform pre-backoff (UPBO) scheme. Full article

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

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16 pages, 2474 KiB

Open AccessArticle

A Hybrid Feature Model and Deep-Learning-Based Bearing Fault Diagnosis

by Muhammad Sohaib¹, Cheol-Hong Kim² and Jong-Myon Kim^1,*

¹ Department of Electrical, Electronics and Computer Engineering, University of Ulsan, Ulsan 44610, Korea

² School of Electronics and Computer Engineering, Chonnam National University, Gwangju 61186, Korea

Sensors 2017, 17(12), 2876; https://doi.org/10.3390/s17122876 - 11 Dec 2017

Cited by 184 | Viewed by 11739

Abstract

Bearing fault diagnosis is imperative for the maintenance, reliability, and durability of rotary machines. It can reduce economical losses by eliminating unexpected downtime in industry due to failure of rotary machines. Though widely investigated in the past couple of decades, continued advancement is [...] Read more.

Bearing fault diagnosis is imperative for the maintenance, reliability, and durability of rotary machines. It can reduce economical losses by eliminating unexpected downtime in industry due to failure of rotary machines. Though widely investigated in the past couple of decades, continued advancement is still desirable to improve upon existing fault diagnosis techniques. Vibration acceleration signals collected from machine bearings exhibit nonstationary behavior due to variable working conditions and multiple fault severities. In the current work, a two-layered bearing fault diagnosis scheme is proposed for the identification of fault pattern and crack size for a given fault type. A hybrid feature pool is used in combination with sparse stacked autoencoder (SAE)-based deep neural networks (DNNs) to perform effective diagnosis of bearing faults of multiple severities. The hybrid feature pool can extract more discriminating information from the raw vibration signals, to overcome the nonstationary behavior of the signals caused by multiple crack sizes. More discriminating information helps the subsequent classifier to effectively classify data into the respective classes. The results indicate that the proposed scheme provides satisfactory performance in diagnosing bearing defects of multiple severities. Moreover, the results also demonstrate that the proposed model outperforms other state-of-the-art algorithms, i.e., support vector machines (SVMs) and backpropagation neural networks (BPNNs). Full article

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

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16 pages, 18652 KiB

Open AccessArticle

Modular Bayesian Networks with Low-Power Wearable Sensors for Recognizing Eating Activities

by Kee-Hoon Kim and Sung-Bae Cho^*

Department of Computer Science, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea

Sensors 2017, 17(12), 2877; https://doi.org/10.3390/s17122877 - 11 Dec 2017

Cited by 15 | Viewed by 4911

Abstract

Recently, recognizing a user’s daily activity using a smartphone and wearable sensors has become a popular issue. However, in contrast with the ideal definition of an experiment, there could be numerous complex activities in real life with respect to its various background and [...] Read more.

Recently, recognizing a user’s daily activity using a smartphone and wearable sensors has become a popular issue. However, in contrast with the ideal definition of an experiment, there could be numerous complex activities in real life with respect to its various background and contexts: time, space, age, culture, and so on. Recognizing these complex activities with limited low-power sensors, considering the power and memory constraints of the wearable environment and the user’s obtrusiveness at once is not an easy problem, although it is very crucial for the activity recognizer to be practically useful. In this paper, we recognize activity of eating, which is one of the most typical examples of a complex activity, using only daily low-power mobile and wearable sensors. To organize the related contexts systemically, we have constructed the context model based on activity theory and the “Five W’s”, and propose a Bayesian network with 88 nodes to predict uncertain contexts probabilistically. The structure of the proposed Bayesian network is designed by a modular and tree-structured approach to reduce the time complexity and increase the scalability. To evaluate the proposed method, we collected the data with 10 different activities from 25 volunteers of various ages, occupations, and jobs, and have obtained 79.71% accuracy, which outperforms other conventional classifiers by 7.54–14.4%. Analyses of the results showed that our probabilistic approach could also give approximate results even when one of contexts or sensor values has a very heterogeneous pattern or is missing. Full article

(This article belongs to the Special Issue Smart Sensing Technologies for Personalised Coaching)

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15 pages, 4935 KiB

Open AccessArticle

Evaluation of Propagation Characteristics Using the Human Body as an Antenna

by Jingzhen Li¹, Zedong Nie^1,*

, Yuhang Liu¹, Lei Wang¹

and Yang Hao²

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

² School of Electronic Engineering and Computer Science, Queen Mary College, University of London, London E1 4NS, UK

Sensors 2017, 17(12), 2878; https://doi.org/10.3390/s17122878 - 11 Dec 2017

Cited by 22 | Viewed by 6721

Abstract

In this paper, an inhomogeneous human body model was presented to investigate the propagation characteristics when the human body was used as an antenna to achieve signal transmission. Specifically, the channel gain of four scenarios, namely, (1) both TX electrode and RX electrode [...] Read more.

In this paper, an inhomogeneous human body model was presented to investigate the propagation characteristics when the human body was used as an antenna to achieve signal transmission. Specifically, the channel gain of four scenarios, namely, (1) both TX electrode and RX electrode were placed in the air, (2) TX electrode was attached on the human body, and RX electrode was placed in the air, (3) TX electrode was placed in the air, and RX electrode was attached on the human body, (4) both the TX electrode and RX electrode were attached on the human body, were studied through numerical simulation in the frequency range 1 MHz to 90 MHz. Furthermore, the comparisons of input efficiency, accepted efficiency, total efficiency, absorption power of human body, and electric field distribution of different distances of four aforementioned scenarios were explored when the frequency was at 44 MHz. In addition, the influences of different human tissues, electrode position, and the distance between electrode and human body on the propagation characteristics were investigated respectively at 44 MHz. The results showed that the channel gain of Scenario 4 was the maximum when the frequency was from 1 MHz to 90 MHz. The propagation characteristics were almost independent of electrode position when the human body was using as an antenna. However, as the distance between TX electrode and human body increased, the channel gain decreased rapidly. The simulations were verified by experimental measurements. The results showed that the simulations were in agreement with the measurements. Full article

(This article belongs to the Special Issue Internet of Wearable and Implantable Medical Things: Theory and Applications)

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8 pages, 3911 KiB

Open AccessArticle

Refractive Index Sensor Based on a Metal–Insulator–Metal Waveguide Coupled with a Symmetric Structure

by Shubin Yan^1,*,†, Meng Zhang^1,†, Xuefeng Zhao¹, Yanjun Zhang¹, Jicheng Wang² and Wen Jin³

¹ Science and Technology on Electronic Test and Measurement Laboratory, North University of China, No. 3 Xueyuan Road, Taiyuan 030051, China

² School of Science, Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, Jiangnan University, Wuxi 214122, China

³ Aerospace Science and Technology Corporation, Beijing Institute of Space Long March Vehicle, Beijing 100036, China

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2879; https://doi.org/10.3390/s17122879 - 11 Dec 2017

Cited by 60 | Viewed by 4950

Abstract

In this study, a new refractive index sensor based on a metal–insulator–metal waveguide coupled with a notched ring resonator and stub is designed. The finite element method is used to study the propagation characteristics of the sensor. According to the calculation results, the [...] Read more.

In this study, a new refractive index sensor based on a metal–insulator–metal waveguide coupled with a notched ring resonator and stub is designed. The finite element method is used to study the propagation characteristics of the sensor. According to the calculation results, the transmission spectrum exhibits a typical Fano resonance shape. The phenomenon of Fano resonance is caused by the coupling between the broadband spectrum and narrowband spectrum. In the design, the broadband spectrum signal is generated by the stub, while the narrowband spectrum signal is generated by the notched ring resonator. In addition, the structural parameters of the resonators and the structure filled with media of different refractive indices are varied to study the sensing properties. The maximum achieved sensitivity of the sensor reached 1071.4 nm/RIU. The results reveal potential applications of the coupled system in the field of sensors. Full article

(This article belongs to the Section Physical Sensors)

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16 pages, 29299 KiB

Open AccessArticle

Active Wireless System for Structural Health Monitoring Applications

by Ricardo Perera^1,*, Alberto Pérez¹

, Marta García-Diéguez² and José Luis Zapico-Valle²

¹ Department of Mechanical Engineering, Technical University of Madrid, 28006 Madrid, Spain

² Department of Construction and Manufacturing Engineering, University of Oviedo, Campus de Gijón, 33203 Gijón, Spain

Sensors 2017, 17(12), 2880; https://doi.org/10.3390/s17122880 - 11 Dec 2017

Cited by 62 | Viewed by 7117

Abstract

The use of wireless sensors in Structural Health Monitoring (SHM) has increased significantly in the last years. Piezoelectric-based lead zirconium titanate (PZT) sensors have been on the rise in SHM due to their superior sensing abilities. They are applicable in different technologies such [...] Read more.

The use of wireless sensors in Structural Health Monitoring (SHM) has increased significantly in the last years. Piezoelectric-based lead zirconium titanate (PZT) sensors have been on the rise in SHM due to their superior sensing abilities. They are applicable in different technologies such as electromechanical impedance (EMI)-based SHM. This work develops a flexible wireless smart sensor (WSS) framework based on the EMI method using active sensors for full-scale and autonomous SHM. In contrast to passive sensors, the self-sensing properties of the PZTs allow interrogating with or exciting a structure when desired. The system integrates the necessary software and hardware within a service-oriented architecture approach able to provide in a modular way the services suitable to satisfy the key requirements of a WSS. The framework developed in this work has been validated on different experimental applications. Initially, the reliability of the EMI method when carried out with the proposed wireless sensor system is evaluated by comparison with the wireless counterpart. Afterwards, the performance of the system is evaluated in terms of software stability and reliability of functioning. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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14 pages, 6582 KiB

Open AccessArticle

On-Line Corrosion Monitoring of Plate Structures Based on Guided Wave Tomography Using Piezoelectric Sensors

by Jing Rao¹, Madis Ratassepp^1,2, Danylo Lisevych¹, Mahadhir Hamzah Caffoor¹ and Zheng Fan^1,*

¹ School of Mechanical & Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore

² Department of Civil Engineering and Architecture, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia

Sensors 2017, 17(12), 2882; https://doi.org/10.3390/s17122882 - 12 Dec 2017

Cited by 52 | Viewed by 6595

Abstract

Corrosion is a major safety and economic concern to various industries. In this paper, a novel ultrasonic guided wave tomography (GWT) system based on self-designed piezoelectric sensors is presented for on-line corrosion monitoring of large plate-like structures. Accurate thickness reconstruction of corrosion damages [...] Read more.

Corrosion is a major safety and economic concern to various industries. In this paper, a novel ultrasonic guided wave tomography (GWT) system based on self-designed piezoelectric sensors is presented for on-line corrosion monitoring of large plate-like structures. Accurate thickness reconstruction of corrosion damages is achieved by using the dispersive regimes of selected guided waves and a reconstruction algorithm based on full waveform inversion (FWI). The system makes use of an array of miniaturised piezoelectric transducers that are capable of exciting and receiving highly dispersive A0 Lamb wave mode at low frequencies. The scattering from transducer array has been found to have a small effect on the thickness reconstruction. The efficiency and the accuracy of the new system have been demonstrated through continuous forced corrosion experiments. The FWI reconstructed thicknesses show good agreement with analytical predictions obtained by Faraday’s law and laser measurements, and more importantly, the thickness images closely resemble the actual corrosion sites. Full article

(This article belongs to the Section Sensor Networks)

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27 pages, 5614 KiB

Open AccessArticle

The Anomalous Influence of Spectral Resolution on Pulsed THz Time Domain Spectroscopy under Real Conditions

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

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

Sensors 2017, 17(12), 2883; https://doi.org/10.3390/s17122883 - 12 Dec 2017

Cited by 1 | Viewed by 3011

Abstract

We have studied the spectral resolution influence on the accuracy of the substance detection and identification at using a broadband THz pulse measured under real conditions (at a distance of more than 3 m from a THz emitter in ambient air with a [...] Read more.

We have studied the spectral resolution influence on the accuracy of the substance detection and identification at using a broadband THz pulse measured under real conditions (at a distance of more than 3 m from a THz emitter in ambient air with a relative humidity of about 50%). We show that increasing spectral resolution leads to manifestation of small-scale perturbations (random fluctuations) in the signal spectrum caused by the influence of the environment or the sample structure. Decreasing the spectral resolution allows us to exclude from consideration this small-scale modulation of the signal as well as to detect the water vapor absorption frequencies. This fact is important in practice because it allows us to increase the signal processing rate. In order to increase the detection reliability, it is advisable to decrease the spectral resolution up to values of not more than 40% of the corresponding spectral line bandwidth. The method of spectral dynamics analysis together with the integral correlation criteria is used for the substance detection and identification. Neutral substances such as chocolate and cookies are used as the samples in the physical experiment. Full article

(This article belongs to the Section Physical Sensors)

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15 pages, 6634 KiB

Open AccessArticle

Rational Design Approach for Enhancing Higher-Mode Response of a Microcantilever in Vibro-Impacting Mode

by Ieva Migliniene¹, Vytautas Ostasevicius¹, Rimvydas Gaidys¹, Rolanas Dauksevicius¹, Giedrius Janusas^2,*

, Vytautas Jurenas¹ and Povilas Krasauskas¹

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

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

Sensors 2017, 17(12), 2884; https://doi.org/10.3390/s17122884 - 12 Dec 2017

Cited by 5 | Viewed by 3565

Abstract

This paper proposes an approach for designing an efficient vibration energy harvester based on a vibro-impacting piezoelectric microcantilever with a geometric shape that has been rationally modified in accordance with results of dynamic optimization. The design goal is to increase the amplitudes of [...] Read more.

This paper proposes an approach for designing an efficient vibration energy harvester based on a vibro-impacting piezoelectric microcantilever with a geometric shape that has been rationally modified in accordance with results of dynamic optimization. The design goal is to increase the amplitudes of higher-order vibration modes induced during the vibro-impact response of the piezoelectric transducer, thereby providing a means to improve the energy conversion efficiency and power output. A rational configuration of the energy harvester is proposed and it is demonstrated that the new design retains essential modal characteristics of the optimal microcantilever structures, further providing the added benefit of less costly fabrication. The effects of structural dynamics associated with advantageous exploitation of higher vibration modes are analyzed experimentally by means of laser vibrometry as well as numerically via transient simulations of microcantilever response to random excitation. Electrical characterization results indicate that the proposed harvester outperforms its conventional counterpart (based on the microcantilever of the constant cross-section) in terms of generated electrical output. Reported results may serve for the development of impact-type micropower generators with harvesting performance that is enhanced by virtue of self-excitation of large intensity higher-order mode responses when the piezoelectric transducer is subjected to relatively low-frequency excitation with strongly variable vibration magnitudes. Full article

(This article belongs to the Section Physical Sensors)

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14 pages, 5637 KiB

Open AccessArticle

Vibration Sensor Monitoring of Nickel-Titanium Alloy Turning for Machinability Evaluation

by Tiziana Segreto^1,2,*, Alessandra Caggiano^1,3

, Sara Karam⁴ and Roberto Teti^1,2

¹ Fraunhofer Joint Laboratory of Excellence on Advanced Production Technology (Fh-J_LEAPT Naples), P.le Tecchio 80, 80125 Naples, Italy

² Department of Chemical, Materials and Industrial Production Engineering, University of Naples Federico II, P.le Tecchio 80, 80125 Naples, Italy

³ Department of Industrial Engineering, University of Naples Federico II, P.le Tecchio 80, 80125 Naples, Italy

⁴ South Eastern Applied Material Research Centre, WIT, Applied Technology Building, Paddy Browns Road, X91 TX03 Waterford, Ireland

Sensors 2017, 17(12), 2885; https://doi.org/10.3390/s17122885 - 12 Dec 2017

Cited by 16 | Viewed by 5643

Abstract

Nickel-Titanium (Ni-Ti) alloys are very difficult-to-machine materials causing notable manufacturing problems due to their unique mechanical properties, including superelasticity, high ductility, and severe strain-hardening. In this framework, the aim of this paper is to assess the machinability of Ni-Ti alloys with reference to [...] Read more.

Nickel-Titanium (Ni-Ti) alloys are very difficult-to-machine materials causing notable manufacturing problems due to their unique mechanical properties, including superelasticity, high ductility, and severe strain-hardening. In this framework, the aim of this paper is to assess the machinability of Ni-Ti alloys with reference to turning processes in order to realize a reliable and robust in-process identification of machinability conditions. An on-line sensor monitoring procedure based on the acquisition of vibration signals was implemented during the experimental turning tests. The detected vibration sensorial data were processed through an advanced signal processing method in time-frequency domain based on wavelet packet transform (WPT). The extracted sensorial features were used to construct WPT pattern feature vectors to send as input to suitably configured neural networks (NNs) for cognitive pattern recognition in order to evaluate the correlation between input sensorial information and output machinability conditions. Full article

(This article belongs to the Special Issue Mechatronic Systems for Automatic Vehicles)

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13 pages, 5733 KiB

Open AccessArticle

Development and Verification of a Novel Robot-Integrated Fringe Projection 3D Scanning System for Large-Scale Metrology

by Hui Du^1,2, Xiaobo Chen^1,2, Juntong Xi^1,2,3,*, Chengyi Yu^1,2 and Bao Zhao^1,2

¹ School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

² Shanghai Key Laboratory of Advanced Manufacturing Environment, Shanghai 200030, China

³ State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, China

Sensors 2017, 17(12), 2886; https://doi.org/10.3390/s17122886 - 12 Dec 2017

Cited by 39 | Viewed by 7249

Abstract

Large-scale surfaces are prevalent in advanced manufacturing industries, and 3D profilometry of these surfaces plays a pivotal role for quality control. This paper proposes a novel and flexible large-scale 3D scanning system assembled by combining a robot, a binocular structured light scanner and [...] Read more.

Large-scale surfaces are prevalent in advanced manufacturing industries, and 3D profilometry of these surfaces plays a pivotal role for quality control. This paper proposes a novel and flexible large-scale 3D scanning system assembled by combining a robot, a binocular structured light scanner and a laser tracker. The measurement principle and system construction of the integrated system are introduced. A mathematical model is established for the global data fusion. Subsequently, a robust method is introduced for the establishment of the end coordinate system. As for hand-eye calibration, the calibration ball is observed by the scanner and the laser tracker simultaneously. With this data, the hand-eye relationship is solved, and then an algorithm is built to get the transformation matrix between the end coordinate system and the world coordinate system. A validation experiment is designed to verify the proposed algorithms. Firstly, a hand-eye calibration experiment is implemented and the computation of the transformation matrix is done. Then a car body rear is measured 22 times in order to verify the global data fusion algorithm. The 3D shape of the rear is reconstructed successfully. To evaluate the precision of the proposed method, a metric tool is built and the results are presented. Full article

(This article belongs to the Special Issue Smart Sensors for Mechatronic and Robotic Systems)

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12 pages, 2500 KiB

Open AccessArticle

In Vivo Non-Destructive Monitoring of Capsicum Annuum Seed Growth with Diverse NaCl Concentrations Using Optical Detection Technique

by Naresh Kumar Ravichandran¹

, Ruchire Eranga Wijesinghe¹, Muhammad Faizan Shirazi¹

, Jeehyun Kim¹, Hee-Young Jung^2,*, Mansik Jeon^1,* and Seung-Yeol Lee²

¹ School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Korea

² School of Applied Biosciences, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Korea

Sensors 2017, 17(12), 2887; https://doi.org/10.3390/s17122887 - 12 Dec 2017

Cited by 12 | Viewed by 4655

Abstract

We demonstrate that optical coherence tomography (OCT) is a plausible optical tool for in vivo detection of plant seeds and its morphological changes during growth. To investigate the direct impact of salt stress on seed germination, the experiment was conducted using Capsicum annuum [...] Read more.

We demonstrate that optical coherence tomography (OCT) is a plausible optical tool for in vivo detection of plant seeds and its morphological changes during growth. To investigate the direct impact of salt stress on seed germination, the experiment was conducted using Capsicum annuum seeds that were treated with different molar concentrations of NaCl. To determine the optimal concentration for the seed growth, the seeds were monitored for nine consecutive days. In vivo two-dimensional OCT images of the treated seeds were obtained and compared with the images of seeds that were grown using sterile distilled water. The obtained results confirm the feasibility of using OCT for the proposed application. Normalized depth profile analysis was utilized to support the conclusions. Full article

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

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22 pages, 13606 KiB

Open AccessArticle

A Data-Driven Response Virtual Sensor Technique with Partial Vibration Measurements Using Convolutional Neural Network

by Shan-Bin Sun¹, Yuan-Yuan He^1,2,3, Si-Da Zhou^1,2,3,* and Zhen-Jiang Yue¹

¹ School of Aerospace Engineering, Beijing Institute of Technology, Zhongguancun South Street 5, Beijing 100081, China

² Key Laboratory of Dynamics and Control of Flight Vehicle, Ministry of Education, Beijing 100081, China

³ Key Laboratory of Autonomous Navigation and Control for Deep Space Exploration, Ministry of Industry and Information Technology, Beijing 100081, China

Sensors 2017, 17(12), 2888; https://doi.org/10.3390/s17122888 - 12 Dec 2017

Cited by 45 | Viewed by 5236

Abstract

Measurement of dynamic responses plays an important role in structural health monitoring, damage detection and other fields of research. However, in aerospace engineering, the physical sensors are limited in the operational conditions of spacecraft, due to the severe environment in outer space. This [...] Read more.

Measurement of dynamic responses plays an important role in structural health monitoring, damage detection and other fields of research. However, in aerospace engineering, the physical sensors are limited in the operational conditions of spacecraft, due to the severe environment in outer space. This paper proposes a virtual sensor model with partial vibration measurements using a convolutional neural network. The transmissibility function is employed as prior knowledge. A four-layer neural network with two convolutional layers, one fully connected layer, and an output layer is proposed as the predicting model. Numerical examples of two different structural dynamic systems demonstrate the performance of the proposed approach. The excellence of the novel technique is further indicated using a simply supported beam experiment comparing to a modal-model-based virtual sensor, which uses modal parameters, such as mode shapes, for estimating the responses of the faulty sensors. The results show that the presented data-driven response virtual sensor technique can predict structural response with high accuracy. Full article

(This article belongs to the Section Intelligent Sensors)

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16 pages, 5309 KiB

Open AccessArticle

Consistently Sampled Correlation Filters with Space Anisotropic Regularization for Visual Tracking

by Guokai Shi¹, Tingfa Xu^1,2,*, Jie Guo¹

, Jiqiang Luo¹ and Yuankun Li¹

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

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

Sensors 2017, 17(12), 2889; https://doi.org/10.3390/s17122889 - 12 Dec 2017

Cited by 3 | Viewed by 3321

Abstract

Most existing correlation filter-based tracking algorithms, which use fixed patches and cyclic shifts as training and detection measures, assume that the training samples are reliable and ignore the inconsistencies between training samples and detection samples. We propose to construct and study a consistently [...] Read more.

Most existing correlation filter-based tracking algorithms, which use fixed patches and cyclic shifts as training and detection measures, assume that the training samples are reliable and ignore the inconsistencies between training samples and detection samples. We propose to construct and study a consistently sampled correlation filter with space anisotropic regularization (CSSAR) to solve these two problems simultaneously. Our approach constructs a spatiotemporally consistent sample strategy to alleviate the redundancies in training samples caused by the cyclical shifts, eliminate the inconsistencies between training samples and detection samples, and introduce space anisotropic regularization to constrain the correlation filter for alleviating drift caused by occlusion. Moreover, an optimization strategy based on the Gauss-Seidel method was developed for obtaining robust and efficient online learning. Both qualitative and quantitative evaluations demonstrate that our tracker outperforms state-of-the-art trackers in object tracking benchmarks (OTBs). Full article

(This article belongs to the Section Physical Sensors)

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36 pages, 1215 KiB

Open AccessArticle

Performance Analysis of the IEEE 802.11p Multichannel MAC Protocol in Vehicular Ad Hoc Networks

by Caixia Song

College of Science and Information, Qingdao Agricultural University, Qingdao 266109, China

Sensors 2017, 17(12), 2890; https://doi.org/10.3390/s17122890 - 12 Dec 2017

Cited by 43 | Viewed by 7233

Abstract

Vehicular Ad Hoc Networks (VANETs) employ multichannel to provide a variety of safety and non-safety applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. The safety applications require timely and reliable transmissions, while the non-safety applications require efficient and high throughput. In [...] Read more.

Vehicular Ad Hoc Networks (VANETs) employ multichannel to provide a variety of safety and non-safety applications, based on the IEEE 802.11p and IEEE 1609.4 protocols. The safety applications require timely and reliable transmissions, while the non-safety applications require efficient and high throughput. In the IEEE 1609.4 protocol, operating interval is divided into alternating Control Channel (CCH) interval and Service Channel (SCH) interval with an identical length. During the CCH interval, nodes transmit safety-related messages and control messages, and Enhanced Distributed Channel Access (EDCA) mechanism is employed to allow four Access Categories (ACs) within a station with different priorities according to their criticality for the vehicle’s safety. During the SCH interval, the non-safety massages are transmitted. An analytical model is proposed in this paper to evaluate performance, reliability and efficiency of the IEEE 802.11p and IEEE 1609.4 protocols. The proposed model improves the existing work by taking serval aspects and the character of multichannel switching into design consideration. Extensive performance evaluations based on analysis and simulation help to validate the accuracy of the proposed model and analyze the capabilities and limitations of the IEEE 802.11p and IEEE 1609.4 protocols, and enhancement suggestions are given. Full article

(This article belongs to the Section Sensor Networks)

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10 pages, 2348 KiB

Open AccessArticle

Development of a Sequential Injection Analysis System for the Determination of Saccharin

by Budi Wibowotomo^1,2, Jong-Bang Eun¹ and Jong Il Rhee^3,*

¹ Department of Food Science and Technology and Functional Food Research Center, Chonnam National University, YongBong-Ro 77, Gwangju 61186, Korea

² Department of Industrial Technology, The State University of Malang, Jl Semarang 5, Malang 65145, Indonesia

³ School of Chemical Engineering and Research Center for Biophotonics, Chonnam National University, YongBong-Ro 77, Gwangju 61186, Korea

Sensors 2017, 17(12), 2891; https://doi.org/10.3390/s17122891 - 12 Dec 2017

Cited by 3 | Viewed by 5304

Abstract

Saccharin is a powerfully sweet nonnutritive sweetener that has been approved for food-processing applications within the range of 100–1200 mg/kg. A simple, rapid, and cost-effective sequential injection analysis (SIA) technique was developed to determine the saccharin level. This method is based on the [...] Read more.

Saccharin is a powerfully sweet nonnutritive sweetener that has been approved for food-processing applications within the range of 100–1200 mg/kg. A simple, rapid, and cost-effective sequential injection analysis (SIA) technique was developed to determine the saccharin level. This method is based on the reaction of saccharin with p-chloranil in an ethanol medium with a hydrogen peroxide (H₂O₂) acceleration, and the resultant violet-red compound was detected using a UV-Vis spectrophotometer at λ_max = 420 nm. To ascertain the optimal conditions for the SIA system, several parameters were investigated, including buffer flow rate and volume, p-chloranil concentration, and reactant volumes (saccharin, p-chloranil, and H₂O₂). The optimum setup of the SIA system was achieved with a buffer flow rate, buffer volume, and draw-up time of 1.2 mL/min, 2900 µL, and ~145 s, respectively. The optimal p-chloranil concentration is 30 mM, and the best reactant volumes, presented in an ordered sequence, are as follows: 30 µL of H₂O₂, 450 µL of saccharin, and 150 µL of p-chloranil. The optimized SIA configuration produced a good linear calibration curve with a correlation coefficient (R² = 0.9812) in the concentration range of 20–140 mg/L and with a detection limit of 19.69 mg/L. Analytical applications in different food categories also showed acceptable recovery values in the range of 93.1–111.5%. This simple and rapid SIA system offers great feasibility for the saccharin quality control in food-product processing. Full article

(This article belongs to the Special Issue Sensing in Flow Analysis 2017)

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16 pages, 6432 KiB

Open AccessArticle

Real-Time Monitoring in Home-Based Cardiac Rehabilitation Using Wrist-Worn Heart Rate Devices

by Javier Medina Quero^1,*

, María Rosa Fernández Olmo², María Dolores Peláez Aguilera³ and Macarena Espinilla Estévez¹

¹ Department of Computer Science, University of Jaen, Campus Las Lagunillas, 23071 Jaén, Spain

² Heart Rehabilitation Unit of the Hospital Complex of Jaén, Av. del Ejército Español 10, 23007 Jaén, Spain

³ Council of Health for the Andalucian Health Service, Av. de la Constitucion 18, 41071 Sevilla, Spain

Sensors 2017, 17(12), 2892; https://doi.org/10.3390/s17122892 - 12 Dec 2017

Cited by 26 | Viewed by 6706

Abstract

Cardiac rehabilitation is a key program which significantly reduces the mortality in at-risk patients with ischemic heart disease; however, there is a lack of accessibility to these programs in health centers. To resolve this issue, home-based programs for cardiac rehabilitation have arisen as [...] Read more.

Cardiac rehabilitation is a key program which significantly reduces the mortality in at-risk patients with ischemic heart disease; however, there is a lack of accessibility to these programs in health centers. To resolve this issue, home-based programs for cardiac rehabilitation have arisen as a potential solution. In this work, we present an approach based on a new generation of wrist-worn devices which have improved the quality of heart rate sensors and applications. Real-time monitoring of rehabilitation sessions based on high-quality clinical guidelines is embedded in a wearable application. For this, a fuzzy temporal linguistic approach models the clinical protocol. An evaluation based on cases is developed by a cardiac rehabilitation team. Full article

(This article belongs to the Special Issue Smart Sensing Technologies for Personalised Coaching)

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26 pages, 2140 KiB

Open AccessArticle

SACFIR: SDN-Based Application-Aware Centralized Adaptive Flow Iterative Reconfiguring Routing Protocol for WSNs

by Muhammad Aslam

, Xiaopeng Hu^* and Fan Wang

School of Computer Science and Technology, Dalian University of Technology, Dalian 116000, China

Sensors 2017, 17(12), 2893; https://doi.org/10.3390/s17122893 - 13 Dec 2017

Cited by 9 | Viewed by 6238

Abstract

Smart reconfiguration of a dynamic networking environment is offered by the central control of Software-Defined Networking (SDN). Centralized SDN-based management architectures are capable of retrieving global topology intelligence and decoupling the forwarding plane from the control plane. Routing protocols developed for conventional Wireless [...] Read more.

Smart reconfiguration of a dynamic networking environment is offered by the central control of Software-Defined Networking (SDN). Centralized SDN-based management architectures are capable of retrieving global topology intelligence and decoupling the forwarding plane from the control plane. Routing protocols developed for conventional Wireless Sensor Networks (WSNs) utilize limited iterative reconfiguration methods to optimize environmental reporting. However, the challenging networking scenarios of WSNs involve a performance overhead due to constant periodic iterative reconfigurations. In this paper, we propose the SDN-based Application-aware Centralized adaptive Flow Iterative Reconfiguring (SACFIR) routing protocol with the centralized SDN iterative solver controller to maintain the load-balancing between flow reconfigurations and flow allocation cost. The proposed SACFIR’s routing protocol offers a unique iterative path-selection algorithm, which initially computes suitable clustering based on residual resources at the control layer and then implements application-aware threshold-based multi-hop report transmissions on the forwarding plane. The operation of the SACFIR algorithm is centrally supervised by the SDN controller residing at the Base Station (BS). This paper extends SACFIR to SDN-based Application-aware Main-value Centralized adaptive Flow Iterative Reconfiguring (SAMCFIR) to establish both proactive and reactive reporting. The SAMCFIR transmission phase enables sensor nodes to trigger direct transmissions for main-value reports, while in the case of SACFIR, all reports follow computed routes. Our SDN-enabled proposed models adjust the reconfiguration period according to the traffic burden on sensor nodes, which results in heterogeneity awareness, load-balancing and application-specific reconfigurations of WSNs. Extensive experimental simulation-based results show that SACFIR and SAMCFIR yield the maximum scalability, network lifetime and stability period when compared to existing routing protocols. Full article

(This article belongs to the Special Issue Software-Defined Networking Based Mobile Networks)

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15 pages, 1662 KiB

Open AccessArticle

Accurate Sample Time Reconstruction of Inertial FIFO Data

by Sebastian Stieber^1,*, Rainer Dorsch² and Christian Haubelt¹

¹ Department of Applied Microelectronics and Computer Engineering, University of Rostock, 18109 Rostock, Germany

² BOSCH Sensortec GmbH, 72770 Reutlingen, Germany

Sensors 2017, 17(12), 2894; https://doi.org/10.3390/s17122894 - 13 Dec 2017

Viewed by 5338

Abstract

In the context of modern cyber-physical systems, the accuracy of underlying sensor data plays an increasingly important role in sensor data fusion and feature extraction. The raw events of multiple sensors have to be aligned in time to enable high quality sensor fusion [...] Read more.

In the context of modern cyber-physical systems, the accuracy of underlying sensor data plays an increasingly important role in sensor data fusion and feature extraction. The raw events of multiple sensors have to be aligned in time to enable high quality sensor fusion results. However, the growing number of simultaneously connected sensor devices make the energy saving data acquisition and processing more and more difficult. Hence, most of the modern sensors offer a first-in-first-out (FIFO) interface to store multiple data samples and to relax timing constraints, when handling multiple sensor devices. However, using the FIFO interface increases the negative influence of individual clock drifts—introduced by fabrication inaccuracies, temperature changes and wear-out effects—onto the sampling data reconstruction. Furthermore, additional timing offset errors due to communication and software latencies increases with a growing number of sensor devices. In this article, we present an approach for an accurate sample time reconstruction independent of the actual clock drift with the help of an internal sensor timer. Such timers are already available in modern sensors, manufactured in micro-electromechanical systems (MEMS) technology. The presented approach focuses on calculating accurate time stamps using the sensor FIFO interface in a forward-only processing manner as a robust and energy saving solution. The proposed algorithm is able to lower the overall standard deviation of reconstructed sampling periods below 40

μ

s, while run-time savings of up to 42% are achieved, compared to single sample acquisition. Full article

(This article belongs to the Section Physical Sensors)

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21 pages, 1246 KiB

Open AccessArticle

Single Channel EEG Artifact Identification Using Two-Dimensional Multi-Resolution Analysis

by Mojtaba Taherisadr¹

, Omid Dehzangi^1,* and Hossein Parsaei²

¹ Computer and Information Science Department, University of Michigan-Dearborn, Dearborn, MI 48128, USA

² Department of Biomedical Physic and Engineering, Shiraz University of Medical Sciences, Fars Province, Shiraz, Zand, Iran

Sensors 2017, 17(12), 2895; https://doi.org/10.3390/s17122895 - 13 Dec 2017

Cited by 18 | Viewed by 5520

Abstract

As a diagnostic monitoring approach, electroencephalogram (EEG) signals can be decoded by signal processing methodologies for various health monitoring purposes. However, EEG recordings are contaminated by other interferences, particularly facial and ocular artifacts generated by the user. This is specifically an issue during [...] Read more.

As a diagnostic monitoring approach, electroencephalogram (EEG) signals can be decoded by signal processing methodologies for various health monitoring purposes. However, EEG recordings are contaminated by other interferences, particularly facial and ocular artifacts generated by the user. This is specifically an issue during continuous EEG recording sessions, and is therefore a key step in using EEG signals for either physiological monitoring and diagnosis or brain–computer interface to identify such artifacts from useful EEG components. In this study, we aim to design a new generic framework in order to process and characterize EEG recording as a multi-component and non-stationary signal with the aim of localizing and identifying its component (e.g., artifact). In the proposed method, we gather three complementary algorithms together to enhance the efficiency of the system. Algorithms include time–frequency (TF) analysis and representation, two-dimensional multi-resolution analysis (2D MRA), and feature extraction and classification. Then, a combination of spectro-temporal and geometric features are extracted by combining key instantaneous TF space descriptors, which enables the system to characterize the non-stationarities in the EEG dynamics. We fit a curvelet transform (as a MRA method) to 2D TF representation of EEG segments to decompose the given space to various levels of resolution. Such a decomposition efficiently improves the analysis of the TF spaces with different characteristics (e.g., resolution). Our experimental results demonstrate that the combination of expansion to TF space, analysis using MRA, and extracting a set of suitable features and applying a proper predictive model is effective in enhancing the EEG artifact identification performance. We also compare the performance of the designed system with another common EEG signal processing technique—namely, 1D wavelet transform. Our experimental results reveal that the proposed method outperforms 1D wavelet. Full article

(This article belongs to the Section Physical Sensors)

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12 pages, 6847 KiB

Open AccessArticle

The Facile Synthesis of Branch-Trunk Ag Hierarchical Nanostructures and Their Applications for High-Performance H₂O₂ Electrochemical Sensors

by Yan Zhang¹, Meiqiong Chen¹, Zhiquan Cai¹, Min Zhang², Peng Liu² and Faliang Cheng^2,*

¹ Department of City and Environmental Sciences, College of Science and Technology of Dongguan of City College, Dongguan 523419, China

² Guangdong Engineering and Technology Research Center for Advanced Nanomaterials, School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, China

Sensors 2017, 17(12), 2896; https://doi.org/10.3390/s17122896 - 13 Dec 2017

Cited by 2 | Viewed by 4820

Abstract

A novel branch-trunk Ag hierarchical nanostructure was synthesized via a galvanic replacement reaction combined with microwave-assisted synthesis using Te nanowire as a sacrificial template. The Te nanowire was synthesized via a hydrothermal process. We further investigated the potential application of the obtained hierarchical [...] Read more.

A novel branch-trunk Ag hierarchical nanostructure was synthesized via a galvanic replacement reaction combined with microwave-assisted synthesis using Te nanowire as a sacrificial template. The Te nanowire was synthesized via a hydrothermal process. We further investigated the potential application of the obtained hierarchical nanostructures in electrochemical sensor analysis. The results showed that the as-prepared sensor exhibited a wide linear range with 0.05 µM to 1.925 mM (R = 0.998) and the detection limit was estimated to be 0.013 µM (S/N = 3). These results indicate the branch-truck Ag hierarchical nanostructures are an excellent candidate material for sensing applications. Full article

(This article belongs to the Special Issue Novel Approaches to Biosensing with Nanoparticles)

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19 pages, 4383 KiB

Open AccessArticle

An Artificial Neural Network for Movement Pattern Analysis to Estimate Blood Alcohol Content Level

by Pedram Gharani^1,*

, Brian Suffoletto², Tammy Chung³

and Hassan A. Karimi¹

¹ Department of Informatics and Networked Systems, University of Pittsburgh School of Computing and Information, Pittsburgh, PA 15260, USA

² Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA

³ Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA

Sensors 2017, 17(12), 2897; https://doi.org/10.3390/s17122897 - 13 Dec 2017

Cited by 27 | Viewed by 5807

Abstract

Impairments in gait occur after alcohol consumption, and, if detected in real-time, could guide the delivery of “just-in-time” injury prevention interventions. We aimed to identify the salient features of gait that could be used for estimating blood alcohol content (BAC) level in a [...] Read more.

Impairments in gait occur after alcohol consumption, and, if detected in real-time, could guide the delivery of “just-in-time” injury prevention interventions. We aimed to identify the salient features of gait that could be used for estimating blood alcohol content (BAC) level in a typical drinking environment. We recruited 10 young adults with a history of heavy drinking to test our research app. During four consecutive Fridays and Saturdays, every hour from 8 p.m. to 12 a.m., they were prompted to use the app to report alcohol consumption and complete a 5-step straight-line walking task, during which 3-axis acceleration and angular velocity data was sampled at a frequency of 100 Hz. BAC for each subject was calculated. From sensor signals, 24 features were calculated using a sliding window technique, including energy, mean, and standard deviation. Using an artificial neural network (ANN), we performed regression analysis to define a model determining association between gait features and BACs. Part (70%) of the data was then used as a training dataset, and the results tested and validated using the rest of the samples. We evaluated different training algorithms for the neural network and the result showed that a Bayesian regularization neural network (BRNN) was the most efficient and accurate. Analyses support the use of the tandem gait task paired with our approach to reliably estimate BAC based on gait features. Results from this work could be useful in designing effective prevention interventions to reduce risky behaviors during periods of alcohol consumption. Full article

(This article belongs to the Section Intelligent Sensors)

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11 pages, 5147 KiB

Open AccessArticle

Fiber Fabry-Perot Force Sensor with Small Volume and High Performance for Assessing Fretting Damage of Steam Generator Tubes

by Peijian Huang, Ning Wang^*, Junying Li, Yong Zhu and Jie Zhang

The Key Laboratory of Optoelectronic Technology & System (Ministry of Education), Chongqing University, Chongqing 400044, China

Sensors 2017, 17(12), 2899; https://doi.org/10.3390/s17122899 - 13 Dec 2017

Cited by 5 | Viewed by 4755

Abstract

Measuring the radial collision force between the steam generator tube (SGT) and the tube support plate (TSP) is essential to assess the fretting damage of the SGT. In order to measure the radial collision force, a novel miniaturized force sensor based on fiber [...] Read more.

Measuring the radial collision force between the steam generator tube (SGT) and the tube support plate (TSP) is essential to assess the fretting damage of the SGT. In order to measure the radial collision force, a novel miniaturized force sensor based on fiber Fabry-Perot (F-P) was designed, and the principle and characteristics of the sensor were analyzed in detail. Then, the F-P force sensor was successfully fabricated and calibrated, and the overall dimensions of the encapsulated fiber F-P sensor were 17 mm × 5 mm × 3 mm (L × W × H). The sensor works well in humid, high pressure (10 MPa), high temperature (350 °C), and vibration (40 kHz) environments. Finally, the F-P force sensors were installed in a 1:1 steam generator test loop, and the radial collision force signals between the SGT and the TSP were obtained. The experiments indicated that the F-P sensor with small volume and high performance could help in assessing the fretting damage of the steam generator tubes. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2017)

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11 pages, 3726 KiB

Open AccessArticle

Low Cost Plastic Optical Fiber Pressure Sensor Embedded in Mattress for Vital Signal Monitoring

by Demetrio Sartiano^* and Salvador Sales

Institute of Telecommunications and Multimedia Applications (iTEAM), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain

Sensors 2017, 17(12), 2900; https://doi.org/10.3390/s17122900 - 13 Dec 2017

Cited by 48 | Viewed by 9446

Abstract

The aim of this paper is to report the design of a low-cost plastic optical fiber (POF) pressure sensor, embedded in a mattress. We report the design of a multipoint sensor, a cheap alternative to the most common fiber sensors. The sensor is [...] Read more.

The aim of this paper is to report the design of a low-cost plastic optical fiber (POF) pressure sensor, embedded in a mattress. We report the design of a multipoint sensor, a cheap alternative to the most common fiber sensors. The sensor is implemented using Arduino board, standard LEDs for optical communication in POF (λ = 645 nm) and a silicon light sensor. The Super ESKA^® plastic fibers were used to implement the fiber intensity sensor, arranged in a 4 × 4 matrix. During the breathing cycles, the force transmitted from the lungs to the thorax is in the order of tens of Newtons, and the respiration rate is of one breath every 2–5 s (0.2–0.5 Hz). The sensor has a resolution of force applied on a single point of 2.2–4.5%/N on the normalized voltage output, and a bandwidth of 10 Hz, it is then suitable to monitor the respiration movements. Another issue to be addressed is the presence of hysteresis over load cycles. The sensor was loaded cyclically to estimate the drift of the system, and the hysteresis was found to be negligible. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2017)

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14 pages, 8412 KiB

Open AccessArticle

Adaptive Wavelet Coding Applied in a Wireless Control System

by Felipe O. S. Gama^*, Luiz F. Q. Silveira and Andrés O. Salazar

Department of Computer Engineering and Automation, Universidade Federal do Rio Grande do Norte, Lagoa Nova, Natal 1524, Brazil

Sensors 2017, 17(12), 2901; https://doi.org/10.3390/s17122901 - 13 Dec 2017

Cited by 3 | Viewed by 3505

Abstract

Wireless control systems can sense, control and act on the information exchanged between the wireless sensor nodes in a control loop. However, the exchanged information becomes susceptible to the degenerative effects produced by the multipath propagation. In order to minimize the destructive effects [...] Read more.

Wireless control systems can sense, control and act on the information exchanged between the wireless sensor nodes in a control loop. However, the exchanged information becomes susceptible to the degenerative effects produced by the multipath propagation. In order to minimize the destructive effects characteristic of wireless channels, several techniques have been investigated recently. Among them, wavelet coding is a good alternative for wireless communications for its robustness to the effects of multipath and its low computational complexity. This work proposes an adaptive wavelet coding whose parameters of code rate and signal constellation can vary according to the fading level and evaluates the use of this transmission system in a control loop implemented by wireless sensor nodes. The performance of the adaptive system was evaluated in terms of bit error rate (BER) versus

E_{b} / N_{0}

and spectral efficiency, considering a time-varying channel with flat Rayleigh fading, and in terms of processing overhead on a control system with wireless communication. The results obtained through computational simulations and experimental tests show performance gains obtained by insertion of the adaptive wavelet coding in a control loop with nodes interconnected by wireless link. These results enable the use of this technique in a wireless link control loop. Full article

(This article belongs to the Section Sensor Networks)

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33 pages, 1497 KiB

Open AccessArticle

Performance Analysis of Cluster Formation in Wireless Sensor Networks

by Edgar Romo Montiel^1,†, Mario E. Rivero-Angeles^1,*,†, Gerardo Rubino^2,†, Heron Molina-Lozano^1,†, Rolando Menchaca-Mendez^1,† and Ricardo Menchaca-Mendez^1,†

¹ Instituto Politécnico Nacional—(CIC-IPN), Mexico City 07738, Mexico

² INRIA Rennes—Bretagne Atlantique, Campus Universitaire de Beaulieu, 35042 Rennes CEDEX, France

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2902; https://doi.org/10.3390/s17122902 - 13 Dec 2017

Cited by 13 | Viewed by 4674

Abstract

Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in [...] Read more.

Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN) use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes. Full article

(This article belongs to the Collection Smart Communication Protocols and Algorithms for Sensor Networks)

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14 pages, 3324 KiB

Open AccessArticle

Improvement of Gaofen-3 Absolute Positioning Accuracy Based on Cross-Calibration

by Mingjun Deng¹, Guo Zhang^2,*

, Ruishan Zhao³

, Shaoning Li²

and Jiansong Li¹

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

² State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China

³ School of Geomatics, Liaoning Technical University, Fuxin 123000, China

Sensors 2017, 17(12), 2903; https://doi.org/10.3390/s17122903 - 14 Dec 2017

Cited by 39 | Viewed by 5093

Abstract

The Chinese Gaofen-3 (GF-3) mission was launched in August 2016, equipped with a full polarimetric synthetic aperture radar (SAR) sensor in the C-band, with a resolution of up to 1 m. The absolute positioning accuracy of GF-3 is of great importance, and in-orbit [...] Read more.

The Chinese Gaofen-3 (GF-3) mission was launched in August 2016, equipped with a full polarimetric synthetic aperture radar (SAR) sensor in the C-band, with a resolution of up to 1 m. The absolute positioning accuracy of GF-3 is of great importance, and in-orbit geometric calibration is a key technology for improving absolute positioning accuracy. Conventional geometric calibration is used to accurately calibrate the geometric calibration parameters of the image (internal delay and azimuth shifts) using high-precision ground control data, which are highly dependent on the control data of the calibration field, but it remains costly and labor-intensive to monitor changes in GF-3’s geometric calibration parameters. Based on the positioning consistency constraint of the conjugate points, this study presents a geometric cross-calibration method for the rapid and accurate calibration of GF-3. The proposed method can accurately calibrate geometric calibration parameters without using corner reflectors and high-precision digital elevation models, thus improving absolute positioning accuracy of the GF-3 image. GF-3 images from multiple regions were collected to verify the absolute positioning accuracy after cross-calibration. The results show that this method can achieve a calibration accuracy as high as that achieved by the conventional field calibration method. Full article

(This article belongs to the Special Issue First Experiences with Chinese Gaofen-3 SAR Sensor)

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23 pages, 4643 KiB

Open AccessArticle

Optimal Multi-Type Sensor Placement for Structural Identification by Static-Load Testing

by Numa Joy Bertola^1,2,*, Maria Papadopoulou¹, Didier Vernay¹ and Ian F. C. Smith²

¹ ETH Zurich, Future Cities Laboratory, Singapore-ETH Centre, 1 CREATE Way, CREATE Tower, Singapore 138602, Singapore

² Applied Computing and Mechanics Laboratory (IMAC), School of Architecture, Civil and Environmental Engineering (ENAC), Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland

Sensors 2017, 17(12), 2904; https://doi.org/10.3390/s17122904 - 14 Dec 2017

Cited by 49 | Viewed by 5415

Abstract

Assessing ageing infrastructure is a critical challenge for civil engineers due to the difficulty in the estimation and integration of uncertainties in structural models. Field measurements are increasingly used to improve knowledge of the real behavior of a structure; this activity is called [...] Read more.

Assessing ageing infrastructure is a critical challenge for civil engineers due to the difficulty in the estimation and integration of uncertainties in structural models. Field measurements are increasingly used to improve knowledge of the real behavior of a structure; this activity is called structural identification. Error-domain model falsification (EDMF) is an easy-to-use model-based structural-identification methodology which robustly accommodates systematic uncertainties originating from sources such as boundary conditions, numerical modelling and model fidelity, as well as aleatory uncertainties from sources such as measurement error and material parameter-value estimations. In most practical applications of structural identification, sensors are placed using engineering judgment and experience. However, since sensor placement is fundamental to the success of structural identification, a more rational and systematic method is justified. This study presents a measurement system design methodology to identify the best sensor locations and sensor types using information from static-load tests. More specifically, three static-load tests were studied for the sensor system design using three types of sensors for a performance evaluation of a full-scale bridge in Singapore. Several sensor placement strategies are compared using joint entropy as an information-gain metric. A modified version of the hierarchical algorithm for sensor placement is proposed to take into account mutual information between load tests. It is shown that a carefully-configured measurement strategy that includes multiple sensor types and several load tests maximizes information gain. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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12 pages, 3378 KiB

Open AccessArticle

Induction of Inflammation In Vivo by Electrocardiogram Sensor Operation Using Wireless Power Transmission

by Jin-Chul Heo¹, Beomjoon Kim², Yoon-Nyun Kim³, Dae-Kwang Kim⁴

and Jong-Ha Lee^1,*

¹ Department of Biomedical Engineering, School of Medicine, Keimyung University, Daegu 42601, Korea

² Department of Electronic and Electrical Engineering, School of Engineering, Keimyung University, Daegu 42601, Korea

³ Department of Internal Medicine, Dongsan Medical Center, Keimyung University, Daegu 41931, Korea

⁴ Department of Medical Genetics, Hanvit Institution for Medical Genetics, Keimyung University, Daegu 42601, Korea

Sensors 2017, 17(12), 2905; https://doi.org/10.3390/s17122905 - 14 Dec 2017

Cited by 7 | Viewed by 4658

Abstract

Prolonged monitoring by cardiac electrocardiogram (ECG) sensors is useful for patients with emergency heart conditions. However, implant monitoring systems are limited by lack of tissue biocompatibility. Here, we developed an implantable ECG sensor for real-time monitoring of ventricular fibrillation and evaluated its biocompatibility [...] Read more.

Prolonged monitoring by cardiac electrocardiogram (ECG) sensors is useful for patients with emergency heart conditions. However, implant monitoring systems are limited by lack of tissue biocompatibility. Here, we developed an implantable ECG sensor for real-time monitoring of ventricular fibrillation and evaluated its biocompatibility using an animal model. The implantable sensor comprised transplant sensors with two electrodes, a wireless power transmission system, and a monitoring system. The sensor was inserted into the subcutaneous tissue of the abdominal area and operated for 1 h/day for 5 days using a wireless power system. Importantly, the sensor was encapsulated by subcutaneous tissue and induced angiogenesis, inflammation, and phagocytosis. In addition, we observed that the levels of inflammation-related markers increased with wireless-powered transmission via the ECG sensor; in particular, levels of the Th-1 cytokine interleukin-12 were significantly increased. The results showed that induced tissue damage was associated with the use of wireless-powered sensors. We also investigated research strategies for the prevention of adverse effects caused by lack of tissue biocompatibility of a wireless-powered ECG monitoring system and provided information on the clinical applications of inflammatory reactions in implant treatment using the wireless-powered transmission system. Full article

(This article belongs to the Special Issue Implantable Sensors 2018)

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22 pages, 1696 KiB

Open AccessArticle

Energy Efficient Real-Time Scheduling Using DPM on Mobile Sensors with a Uniform Multi-Cores

by Youngmin Kim¹, Ki-Seong Lee¹

and Chan-Gun Lee^2,*

¹ Da Vind College of Genneral Education, Chung-Ang University, Heuksuk-ro 84, Dongjak-gu, Seoul 06974, Korea

² Department of Computer Science and Engineering, Chung-Ang University, Heuksuk-ro 84, Dongjak-gu, Seoul 06974, Korea

Sensors 2017, 17(12), 2906; https://doi.org/10.3390/s17122906 - 14 Dec 2017

Cited by 2 | Viewed by 3969

Abstract

In wireless sensor networks (WSNs), sensor nodes are deployed for collecting and analyzing data. These nodes use limited energy batteries for easy deployment and low cost. The use of limited energy batteries is closely related to the lifetime of the sensor nodes when [...] Read more.

In wireless sensor networks (WSNs), sensor nodes are deployed for collecting and analyzing data. These nodes use limited energy batteries for easy deployment and low cost. The use of limited energy batteries is closely related to the lifetime of the sensor nodes when using wireless sensor networks. Efficient-energy management is important to extending the lifetime of the sensor nodes. Most effort for improving power efficiency in tiny sensor nodes has focused mainly on reducing the power consumed during data transmission. However, recent emergence of sensor nodes equipped with multi-cores strongly requires attention to be given to the problem of reducing power consumption in multi-cores. In this paper, we propose an energy efficient scheduling method for sensor nodes supporting a uniform multi-cores. We extend the proposed T-Ler plane based scheduling for global optimal scheduling of a uniform multi-cores and multi-processors to enable power management using dynamic power management. In the proposed approach, processor selection for a scheduling and mapping method between the tasks and processors is proposed to efficiently utilize dynamic power management. Experiments show the effectiveness of the proposed approach compared to other existing methods. Full article

(This article belongs to the Special Issue Mobile Sensing Applications)

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22 pages, 4753 KiB

Open AccessArticle

Centralized Networks to Generate Human Body Motions

by Sergei Vakulenko^1,2, Ovidiu Radulescu³

, Ivan Morozov⁴ and Andres Weber^4,*

¹ Institute for Mechanical Engineering Problems, 195251 Saint Petersburg, Russia

² Mechanics and Optics, Saint Petersburg National Research University of Information Technologies, 191119 Saint Petersburg, Russia

³ DIMNP-UMR 5235 CNRS/UM, University of Montpellier, 34095 Montpellier, France

⁴ Computer Science Department, University of Bonn, 53113 Bonn, Germany

Sensors 2017, 17(12), 2907; https://doi.org/10.3390/s17122907 - 14 Dec 2017

Cited by 5 | Viewed by 4262

Abstract

We consider continuous-time recurrent neural networks as dynamical models for the simulation of human body motions. These networks consist of a few centers and many satellites connected to them. The centers evolve in time as periodical oscillators with different frequencies. The center states [...] Read more.

We consider continuous-time recurrent neural networks as dynamical models for the simulation of human body motions. These networks consist of a few centers and many satellites connected to them. The centers evolve in time as periodical oscillators with different frequencies. The center states define the satellite neurons’ states by a radial basis function (RBF) network. To simulate different motions, we adjust the parameters of the RBF networks. Our network includes a switching module that allows for turning from one motion to another. Simulations show that this model allows us to simulate complicated motions consisting of many different dynamical primitives. We also use the model for learning human body motion from markers’ trajectories. We find that center frequencies can be learned from a small number of markers and can be transferred to other markers, such that our technique seems to be capable of correcting for missing information resulting from sparse control marker settings. Full article

(This article belongs to the Section Sensor Networks)

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14 pages, 5606 KiB

Open AccessArticle

Fiber-Optic Sensor-Based Remote Acoustic Emission Measurement in a 1000 °C Environment

by Fengming Yu^*

and Yoji Okabe

Institute of Industrial Science, University of Tokyo, Tokyo 153-8505, Japan

Sensors 2017, 17(12), 2908; https://doi.org/10.3390/s17122908 - 14 Dec 2017

Cited by 41 | Viewed by 7925

Abstract

Recently, the authors have proposed a remote acoustic emission (AE) measurement configuration using a sensitive fiber-optic Bragg grating (FBG) sensor. In the configuration, the FBG sensor was remotely bonded on a plate, and an optical fiber was used as the waveguide to propagate [...] Read more.

Recently, the authors have proposed a remote acoustic emission (AE) measurement configuration using a sensitive fiber-optic Bragg grating (FBG) sensor. In the configuration, the FBG sensor was remotely bonded on a plate, and an optical fiber was used as the waveguide to propagate AE waves from the adhesive point to the sensor. The previous work (Yu et al., Smart Materials and Structures 25 (10), 105,033 (2016)) has clarified the sensing principle behind the special remote measurement system that enables accurate remote sensing of AE signals. Since the silica-glass optical fibers have a high heat-resistance exceeding 1000 °C, this work presents a preliminary high-temperature AE detection method by using the optical fiber-based ultrasonic waveguide to propagate the AE from a high-temperature environment to a room-temperature environment, in which the FBG sensor could function as the receiver of the guided wave. As a result, the novel measurement configuration successfully achieved highly sensitive and stable AE detection in an alumina plate at elevated temperatures in the 100 °C to 1000 °C range. Due to its good performance, this detection method will be potentially useful for the non-destructive testing that can be performed in high-temperature environments to evaluate the microscopic damage in heat-resistant materials. Full article

(This article belongs to the Special Issue Optical Fiber Sensors 2017)

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13 pages, 2750 KiB

Open AccessArticle

An Online MFL Sensing Method for Steel Pipe Based on the Magnetic Guiding Effect

by Jianbo Wu¹, Hui Fang^1,*, Xiaoming Huang¹, Hui Xia¹, Yihua Kang² 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(12), 2911; https://doi.org/10.3390/s17122911 - 15 Dec 2017

Cited by 23 | Viewed by 7287

Abstract

In order to improve the sensitivity of online magnetic flux leakage (MFL) testing for steel pipe, a sensing method based on the magnetic guiding effect is proposed and investigated in this paper. Compared to the conventional contact sensing method using a non-ferromagnetic support, [...] Read more.

In order to improve the sensitivity of online magnetic flux leakage (MFL) testing for steel pipe, a sensing method based on the magnetic guiding effect is proposed and investigated in this paper. Compared to the conventional contact sensing method using a non-ferromagnetic support, the proposed method creatively utilizes a ferromagnetic one to guide more magnetic flux to leak out. Based on Hopkinson’s law, the principle of the magnetic guiding effect of the ferromagnetic support is theoretically illustrated. Then, numerical simulations are conducted to investigate the MFL changes influenced by the ferromagnetic support. Finally, the probe based on the proposed method is designed and developed, and online MFL experiments are performed to validate the feasibility of the proposed method. Online tests show that the proposed sensing method can greatly improve the MFL sensitivity. Full article

(This article belongs to the Section Physical Sensors)

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23 pages, 4398 KiB

Open AccessArticle

A Novel Concrete-Based Sensor for Detection of Ice and Water on Roads and Bridges

by Habib Tabatabai^*

and Mohammed Aljuboori

Department of Civil and Environmental Engineering, University of Wisconsin, Milwaukee, 3200 N Cramer St, Milwaukee, WI 53211, USA

Sensors 2017, 17(12), 2912; https://doi.org/10.3390/s17122912 - 14 Dec 2017

Cited by 47 | Viewed by 6524

Abstract

Hundreds of people are killed or injured annually in the United States in accidents related to ice formation on roadways and bridge decks. In this paper, a novel embedded sensor system is proposed for the detection of black ice as well as wet, [...] Read more.

Hundreds of people are killed or injured annually in the United States in accidents related to ice formation on roadways and bridge decks. In this paper, a novel embedded sensor system is proposed for the detection of black ice as well as wet, dry, and frozen pavement conditions on roads, runways, and bridges. The proposed sensor works by detecting changes in electrical resistance between two sets of stainless steel poles embedded in the concrete sensor to assess surface and near-surface conditions. A preliminary decision algorithm is developed that utilizes sensor outputs indicating resistance changes and surface temperature. The sensor consists of a 102-mm-diameter, 38-mm-high, concrete cylinder. Laboratory results indicate that the proposed sensor can effectively detect surface ice and wet conditions even in the presence of deicing chlorides and rubber residue. This sensor can further distinguish black ice from ice that may exist within concrete pores. Full article

(This article belongs to the Section Physical Sensors)

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19 pages, 5247 KiB

Open AccessArticle

High-Speed Video System for Micro-Expression Detection and Recognition

by Diana Borza^1,*, Radu Danescu¹

, Razvan Itu¹

and Adrian Darabant²

¹ Computer Science Department, Technical University of Cluj-Napoca, 28 Memorandumului Street, 400114 Cluj Napoca, Romania

² Computer Science Department, Babes Bolyai University, 58-60 Teodor Mihali Street, C333, 400591 Cluj Napoca, Romania

Sensors 2017, 17(12), 2913; https://doi.org/10.3390/s17122913 - 14 Dec 2017

Cited by 26 | Viewed by 7531

Abstract

Micro-expressions play an essential part in understanding non-verbal communication and deceit detection. They are involuntary, brief facial movements that are shown when a person is trying to conceal something. Automatic analysis of micro-expression is challenging due to their low amplitude and to their [...] Read more.

Micro-expressions play an essential part in understanding non-verbal communication and deceit detection. They are involuntary, brief facial movements that are shown when a person is trying to conceal something. Automatic analysis of micro-expression is challenging due to their low amplitude and to their short duration (they occur as fast as 1/15 to 1/25 of a second). We propose a fully micro-expression analysis system consisting of a high-speed image acquisition setup and a software framework which can detect the frames when the micro-expressions occurred as well as determine the type of the emerged expression. The detection and classification methods use fast and simple motion descriptors based on absolute image differences. The recognition module it only involves the computation of several 2D Gaussian probabilities. The software framework was tested on two publicly available high speed micro-expression databases and the whole system was used to acquire new data. The experiments we performed show that our solution outperforms state of the art works which use more complex and computationally intensive descriptors. Full article

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

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15 pages, 2045 KiB

Open AccessArticle

An Efficient Estimator for Moving Target Localization Using Multi-Station Dual-Frequency Radars

by Jiyan Huang^*

, Ying Zhang and Shan Luo

School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China

Sensors 2017, 17(12), 2914; https://doi.org/10.3390/s17122914 - 15 Dec 2017

Cited by 2 | Viewed by 3154

Abstract

Localization of a moving target in a dual-frequency radars system has now gained considerable attention. The noncoherent localization approach based on a least squares (LS) estimator has been addressed in the literature. Compared with the LS method, a novel localization method based on [...] Read more.

Localization of a moving target in a dual-frequency radars system has now gained considerable attention. The noncoherent localization approach based on a least squares (LS) estimator has been addressed in the literature. Compared with the LS method, a novel localization method based on a two-step weighted least squares estimator is proposed to increase positioning accuracy for a multi-station dual-frequency radars system in this paper. The effects of signal noise ratio and the number of samples on the performance of range estimation are also analyzed in the paper. Furthermore, both the theoretical variance and Cramer–Rao lower bound (CRLB) are derived. The simulation results verified the proposed method. Full article

(This article belongs to the Section Remote Sensors)

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14 pages, 3980 KiB

Open AccessArticle

Response Characterization of an Inexpensive Aerosol Sensor

by Joel Kuula^*

, Timo Mäkelä, Risto Hillamo and Hilkka Timonen

Finnish Meteorological Institue, Erik Palmenin aukio 1, FIN-00560 Helsinki, Finland

Sensors 2017, 17(12), 2915; https://doi.org/10.3390/s17122915 - 15 Dec 2017

Cited by 19 | Viewed by 6022

Abstract

Inexpensive aerosol sensors have been considered as a complementary option to address the issue of expensive but low spatial coverage air quality monitoring networks. However, the accuracy and response characteristics of these sensors is poorly documented. In this study, inexpensive Shinyei PPD42NS and [...] Read more.

Inexpensive aerosol sensors have been considered as a complementary option to address the issue of expensive but low spatial coverage air quality monitoring networks. However, the accuracy and response characteristics of these sensors is poorly documented. In this study, inexpensive Shinyei PPD42NS and PPD60PV sensors were evaluated using a novel laboratory evaluation method. A continuously changing monodisperse size distribution of particles was generated using a Vibrating Orifice Aerosol Generator. Furthermore, the laboratory results were validated in a field experiment. The laboratory tests showed that both of the sensors responded to particulate mass (PM) concentration stimulus, rather than number concentration. The highest detection efficiency for the PPD42NS was within particle size range of 2.5–4 µm, and the respective optimal size range for the PPD60PV was 0.7–1 µm. The field test yielded high PM correlations (R² = 0.962 and R² = 0.986) for viable detection ranges of 1.6–5 and 0.3–1.6 µm, when compared to a medium cost optical dust monitor. As the size distribution of atmospheric particles tends to be bimodal, it is likely that indicatively valid results could be obtained for the PM_10–2.5 size fraction (particulate mass in size range 2.5–10 µm) with the PPD42NS sensor. Respectively, the PPD60PV could possibly be used to measure the PM_2.5 size fraction (particulate mass in size below 2.5 µm). Full article

(This article belongs to the Section Chemical Sensors)

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19 pages, 8076 KiB

Open AccessArticle

Fault Diagnosis of Internal Combustion Engine Valve Clearance Using the Impact Commencement Detection Method

by Zhinong Jiang, Zhiwei Mao

, Zijia Wang and Jinjie Zhang^*

Diagnosis and Self-Recovering Engineering Research Center, Beijing University of Chemical Technology, Beijing 100029, China

Sensors 2017, 17(12), 2916; https://doi.org/10.3390/s17122916 - 15 Dec 2017

Cited by 30 | Viewed by 8433

Abstract

Internal combustion engines (ICEs) are widely used in many important fields. The valve train clearance of an ICE usually exceeds the normal value due to wear or faulty adjustment. This work aims at diagnosing the valve clearance fault based on the vibration signals [...] Read more.

Internal combustion engines (ICEs) are widely used in many important fields. The valve train clearance of an ICE usually exceeds the normal value due to wear or faulty adjustment. This work aims at diagnosing the valve clearance fault based on the vibration signals measured on the engine cylinder heads. The non-stationarity of the ICE operating condition makes it difficult to obtain the nominal baseline, which is always an awkward problem for fault diagnosis. This paper overcomes the problem by inspecting the timing of valve closing impacts, of which the referenced baseline can be obtained by referencing design parameters rather than extraction during healthy conditions. To accurately detect the timing of valve closing impact from vibration signals, we carry out a new method to detect and extract the commencement of the impacts. The results of experiments conducted on a twelve-cylinder ICE test rig show that the approach is capable of extracting the commencement of valve closing impact accurately and using only one feature can give a superior monitoring of valve clearance. With the help of this technique, the valve clearance fault becomes detectable even without the comparison to the baseline, and the changing trend of the clearance could be trackable. Full article

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

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22 pages, 5374 KiB

Open AccessArticle

An Indoor Location-Based Control System Using Bluetooth Beacons for IoT Systems

by Jun-Ho Huh¹

and Kyungryong Seo^2,*

¹ Department of Software, Catholic University of Pusan, Geumjeong-gu, 57 Oryundae-ro, Busan 46252, Korea

² Department of Computer Engineering, Pukyong National University, Busan 48513, Korea

Sensors 2017, 17(12), 2917; https://doi.org/10.3390/s17122917 - 19 Dec 2017

Cited by 119 | Viewed by 11961

Abstract

The indoor location-based control system estimates the indoor position of a user to provide the service he/she requires. The major elements involved in the system are the localization server, service-provision client, user application positioning technology. The localization server controls access of terminal devices [...] Read more.

The indoor location-based control system estimates the indoor position of a user to provide the service he/she requires. The major elements involved in the system are the localization server, service-provision client, user application positioning technology. The localization server controls access of terminal devices (e.g., Smart Phones and other wireless devices) to determine their locations within a specified space first and then the service-provision client initiates required services such as indoor navigation and monitoring/surveillance. The user application provides necessary data to let the server to localize the devices or allow the user to receive various services from the client. The major technological elements involved in this system are indoor space partition method, Bluetooth 4.0, RSSI (Received Signal Strength Indication) and trilateration. The system also employs the BLE communication technology when determining the position of the user in an indoor space. The position information obtained is then used to control a specific device(s). These technologies are fundamental in achieving a “Smart Living”. An indoor location-based control system that provides services by estimating user’s indoor locations has been implemented in this study (First scenario). The algorithm introduced in this study (Second scenario) is effective in extracting valid samples from the RSSI dataset but has it has some drawbacks as well. Although we used a range-average algorithm that measures the shortest distance, there are some limitations because the measurement results depend on the sample size and the sample efficiency depends on sampling speeds and environmental changes. However, the Bluetooth system can be implemented at a relatively low cost so that once the problem of precision is solved, it can be applied to various fields. Full article

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

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18 pages, 2121 KiB

Open AccessArticle

Internet of Things (IoT) Based Design of a Secure and Lightweight Body Area Network (BAN) Healthcare System

by Yong-Yuan Deng¹, Chin-Ling Chen^1,2,*, Woei-Jiunn Tsaur³

, Yung-Wen Tang⁴ and Jung-Hsuan Chen⁵

¹ Department of Computer Science and Information Engineering, Chaoyang University of Technology, Taichung 413, Taiwan

² School of Information Engineering, Changchun Sci-Tech University, Changchun 130600, China

³ Computer Center, National Taipei University, Taipei 237, Taiwan

⁴ School of Physical Therapy, Chun Shan Medical University, Taichung 402, Taiwan

⁵ Department of Industrial Education, National Taiwan Normal University, Taipei 10610, Taiwan

Sensors 2017, 17(12), 2919; https://doi.org/10.3390/s17122919 - 15 Dec 2017

Cited by 34 | Viewed by 5949

Abstract

As sensor networks and cloud computation technologies have rapidly developed over recent years, many services and applications integrating these technologies into daily life have come together as an Internet of Things (IoT). At the same time, aging populations have increased the need for [...] Read more.

As sensor networks and cloud computation technologies have rapidly developed over recent years, many services and applications integrating these technologies into daily life have come together as an Internet of Things (IoT). At the same time, aging populations have increased the need for expanded and more efficient elderly care services. Fortunately, elderly people can now wear sensing devices which relay data to a personal wireless device, forming a body area network (BAN). These personal wireless devices collect and integrate patients’ personal physiological data, and then transmit the data to the backend of the network for related diagnostics. However, a great deal of the information transmitted by such systems is sensitive data, and must therefore be subject to stringent security protocols. Protecting this data from unauthorized access is thus an important issue in IoT-related research. In regard to a cloud healthcare environment, scholars have proposed a secure mechanism to protect sensitive patient information. Their schemes provide a general architecture; however, these previous schemes still have some vulnerability, and thus cannot guarantee complete security. This paper proposes a secure and lightweight body-sensor network based on the Internet of Things for cloud healthcare environments, in order to address the vulnerabilities discovered in previous schemes. The proposed authentication mechanism is applied to a medical reader to provide a more comprehensive architecture while also providing mutual authentication, and guaranteeing data integrity, user untraceability, and forward and backward secrecy, in addition to being resistant to replay attack. Full article

(This article belongs to the Special Issue Selected Papers from IEEE ICICE 2017)

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17 pages, 3067 KiB

Open AccessArticle

Sparse Adaptive Iteratively-Weighted Thresholding Algorithm (SAITA) for L p -Regularization Using the Multiple Sub-Dictionary Representation

by Yunyi Li¹

, Jie Zhang², Shangang Fan², Jie Yang²

, Jian Xiong², Xiefeng Cheng¹, Hikmet Sari², Fumiyuki Adachi³ and Guan Gui^2,*

¹ College of Electronic and Optical Engineering & College of Microelectronics, Nanjing University of Posts and Telecommunications, Nanjing 210023, China

² College of Telecommunication and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China

³ Research Organization of Electrical Communication, Tohoku University, Sendai 980-8577, Japan

Sensors 2017, 17(12), 2920; https://doi.org/10.3390/s17122920 - 15 Dec 2017

Cited by 14 | Viewed by 4543

Abstract

Both

L_{1 / 2}

and

L_{2 / 3}

are two typical non-convex regularizations of

L_{p}

(

0 < p < 1

), which can be employed to obtain a sparser solution than the

L_{1}

regularization. Recently, the multiple-state sparse [...] Read more.

Both

L_{1 / 2}

and

L_{2 / 3}

are two typical non-convex regularizations of

L_{p}

(

0 < p < 1

), which can be employed to obtain a sparser solution than the

L_{1}

regularization. Recently, the multiple-state sparse transformation strategy has been developed to exploit the sparsity in

L_{1}

regularization for sparse signal recovery, which combines the iterative reweighted algorithms. To further exploit the sparse structure of signal and image, this paper adopts multiple dictionary sparse transform strategies for the two typical cases

p \in {1 / 2, 2 / 3}

based on an iterative

L_{p}

thresholding algorithm and then proposes a sparse adaptive iterative-weighted

L_{p}

thresholding algorithm (SAITA). Moreover, a simple yet effective regularization parameter is proposed to weight each sub-dictionary-based

L_{p}

regularizer. Simulation results have shown that the proposed SAITA not only performs better than the corresponding

L_{1}

algorithms but can also obtain a better recovery performance and achieve faster convergence than the conventional single-dictionary sparse transform-based

L_{p}

case. Moreover, we conduct some applications about sparse image recovery and obtain good results by comparison with relative work. Full article

(This article belongs to the Special Issue New Paradigms in Data Sensing and Processing for Edge Computing)

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29 pages, 6372 KiB

Open AccessArticle

Towards Realistic Urban Traffic Experiments Using DFROUTER: Heuristic, Validation and Extensions

by Jorge Luis Zambrano-Martinez^1,*

, Carlos T. Calafate¹

, David Soler²

and Juan-Carlos Cano¹

¹ Department of Computer Engineering (DISCA), Universitat Politècnica de València, 46022 Valencia, Spain

² Institute of Multidisciplinary Mathematics (IMM), Universitat Politècnica de València, 46022 Valencia, Spain

Sensors 2017, 17(12), 2921; https://doi.org/10.3390/s17122921 - 15 Dec 2017

Cited by 29 | Viewed by 6063

Abstract

Traffic congestion is an important problem faced by Intelligent Transportation Systems (ITS), requiring models that allow predicting the impact of different solutions on urban traffic flow. Such an approach typically requires the use of simulations, which should be as realistic as possible. However, [...] Read more.

Traffic congestion is an important problem faced by Intelligent Transportation Systems (ITS), requiring models that allow predicting the impact of different solutions on urban traffic flow. Such an approach typically requires the use of simulations, which should be as realistic as possible. However, achieving high degrees of realism can be complex when the actual traffic patterns, defined through an Origin/Destination (O-D) matrix for the vehicles in a city, remain unknown. Thus, the main contribution of this paper is a heuristic for improving traffic congestion modeling. In particular, we propose a procedure that, starting from real induction loop measurements made available by traffic authorities, iteratively refines the output of DFROUTER, which is a module provided by the SUMO (Simulation of Urban MObility) tool. This way, it is able to generate an O-D matrix for traffic that resembles the real traffic distribution and that can be directly imported by SUMO. We apply our technique to the city of Valencia, and we then compare the obtained results against other existing traffic mobility data for the cities of Cologne (Germany) and Bologna (Italy), thereby validating our approach. We also use our technique to determine what degree of congestion is expectable if certain conditions cause additional traffic to circulate in the city, adopting both a uniform pattern and a hotspot-based pattern for traffic injection to demonstrate how to regulate the overall number of vehicles in the city. This study allows evaluating the impact of vehicle flow changes on the overall traffic congestion levels. Full article

(This article belongs to the Special Issue Smart Vehicular Mobile Sensing)

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9 pages, 1279 KiB

Open AccessArticle

A Highly Sensitive Two-Dimensional Inclinometer Based on Two Etched Chirped-Fiber-Grating Arrays

by Hung-Ying Chang¹, Yu-Chung Chang^2,* and Wen-Fung Liu³

¹ Program of Electrical and Communications Engineering, Feng-Chia University, 100 Wenhwa Rd., Seatwen, Taichung 40724, Taiwan

² Department of Electrical Engineering, National Changhua University of Education, 2 Shida Rd., Changhua 50074, Taiwan

³ Department of Electrical Engineering, Feng-Chia University, 100 Wenhwa Rd., Seatwen, Taichung 40724, Taiwan

Sensors 2017, 17(12), 2922; https://doi.org/10.3390/s17122922 - 15 Dec 2017

Cited by 19 | Viewed by 4626

Abstract

We present a novel two-dimensional fiber-optic inclinometer with high sensitivity by crisscrossing two etched chirped fiber Bragg gratings (CFBG) arrays. Each array is composed of two symmetrically-arranged CFBGs. By etching away most of the claddings of the CFBGs to expose the evanescent wave, [...] Read more.

We present a novel two-dimensional fiber-optic inclinometer with high sensitivity by crisscrossing two etched chirped fiber Bragg gratings (CFBG) arrays. Each array is composed of two symmetrically-arranged CFBGs. By etching away most of the claddings of the CFBGs to expose the evanescent wave, the reflection spectra are highly sensitive to the surrounding index change. When we immerse only part of the CFBG in liquid, the effective index difference induces a superposition peak in the refection spectrum. By interrogating the peak wavelengths of the CFBGs, we can deduce the tilt angle and direction simultaneously. The inclinometer has a resolution of 0.003° in tilt angle measurement and 0.00187 rad in tilt direction measurement. Due to the unique sensing mechanism, the sensor is temperature insensitive. This sensor can be useful in long term continuous monitoring of inclination or in real-time feedback control of tilt angles, especially in harsh environments with violent temperature variation. Full article

(This article belongs to the Section Physical Sensors)

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Graphical abstract

28 pages, 15844 KiB

Open AccessArticle

Middleware for Plug and Play Integration of Heterogeneous Sensor Resources into the Sensor Web

by Enoc Martínez^1,*, Daniel M. Toma¹, Simon Jirka² and Joaquín Del Río¹

¹ SARTI research group, Electronics Department, Universitat Politècnica de Catalunya, 08800 Vilanova i la Geltrú, Spain

² 52∘ North Initiative for Geospatial Open Source Software, 48151 Münster, Germany

Sensors 2017, 17(12), 2923; https://doi.org/10.3390/s17122923 - 15 Dec 2017

Cited by 23 | Viewed by 8183

Abstract

The study of global phenomena requires the combination of a considerable amount of data coming from different sources, acquired by different observation platforms and managed by institutions working in different scientific fields. Merging this data to provide extensive and complete data sets to [...] Read more.

The study of global phenomena requires the combination of a considerable amount of data coming from different sources, acquired by different observation platforms and managed by institutions working in different scientific fields. Merging this data to provide extensive and complete data sets to monitor the long-term, global changes of our oceans is a major challenge. The data acquisition and data archival procedures usually vary significantly depending on the acquisition platform. This lack of standardization ultimately leads to information silos, preventing the data to be effectively shared across different scientific communities. In the past years, important steps have been taken in order to improve both standardization and interoperability, such as the Open Geospatial Consortium’s Sensor Web Enablement (SWE) framework. Within this framework, standardized models and interfaces to archive, access and visualize the data from heterogeneous sensor resources have been proposed. However, due to the wide variety of software and hardware architectures presented by marine sensors and marine observation platforms, there is still a lack of uniform procedures to integrate sensors into existing SWE-based data infrastructures. In this work, a framework aimed to enable sensor plug and play integration into existing SWE-based data infrastructures is presented. First, an analysis of the operations required to automatically identify, configure and operate a sensor are analysed. Then, the metadata required for these operations is structured in a standard way. Afterwards, a modular, plug and play, SWE-based acquisition chain is proposed. Finally different use cases for this framework are presented. Full article

(This article belongs to the Section Intelligent Sensors)

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15 pages, 2902 KiB

Open AccessArticle

POFBG-Embedded Cork Insole for Plantar Pressure Monitoring

by Débora Vilarinho¹, Antreas Theodosiou²

, Cátia Leitão^1,3

, Arnaldo G. Leal-Junior⁴

, Maria De Fátima Domingues^1,3,5

, Kyriacos Kalli²

, Paulo André⁶, Paulo Antunes^1,3

and Carlos Marques^1,3,*

¹ Department of Physics & I3N, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

² Nanophotonics Research Laboratory, Cyprus University of Technology, Limassol 3036, Cyprus

³ Instituto de Telecomunicações, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal

⁴ Telecommunications Laboratory, Electrical Engineering Department, Federal University of Espírito Santo, Fernando Ferrari Avenue, Vitoria 29075-910, ES, Brazil

⁵ Centro de Automática y Robótica, CSIC-UPM, Ctra. Campo Real, Arganda del Rey, 28500 Madrid, Spain

⁶ Instituto de Telecomunicações and Department of Electrical and Computer Engineering, Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal

Sensors 2017, 17(12), 2924; https://doi.org/10.3390/s17122924 - 16 Dec 2017

Cited by 73 | Viewed by 6999

Abstract

We propose a novel polymer optical fiber (POF) sensing system based on fiber Bragg gratings (FBGs) to measure foot plantar pressure. The plantar pressure signals are detected by five FBGs, in the same piece of cyclic transparent optical polymer (CYTOP) fiber, which are [...] Read more.

We propose a novel polymer optical fiber (POF) sensing system based on fiber Bragg gratings (FBGs) to measure foot plantar pressure. The plantar pressure signals are detected by five FBGs, in the same piece of cyclic transparent optical polymer (CYTOP) fiber, which are embedded in a cork insole for the dynamic monitoring of gait. The calibration and measurements performed with the suggested system are presented, and the results obtained demonstrate the accuracy and reliability of the sensing platform to monitor the foot plantar pressure distribution during gait motion and the application of pressure. This architecture does not compromise the patient’s mobility nor interfere in their daily activities. The results using the CYTOP fiber showed a very good response when compared with solutions using silica optical fibers, resulting in a sensitivity almost twice as high, with excellent repeatability and ease of handling. The advantages of POF (e.g., high flexibility and robustness) proved that this is a viable solution for this type of application, since POF’s high fracture toughness enables its application in monitoring patients with higher body mass compared with similar systems based on silica fiber. This study has demonstrated the viability of the proposed system based on POF technology as a useful alternative for plantar pressure detection systems. Full article

(This article belongs to the Special Issue Fiber Bragg Grating Based Sensors)

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22 pages, 4504 KiB

Open AccessArticle

Early Steps in Automated Behavior Mapping via Indoor Sensors

by Taner Arsan^1,* and Orcun Kepez²

¹ Department of Computer Engineering, Kadir Has University, 34083 Istanbul, Turkey

² Department of Interior Architecture and Environmental Design, Kadir Has University, 34083 Istanbul, Turkey

Sensors 2017, 17(12), 2925; https://doi.org/10.3390/s17122925 - 16 Dec 2017

Cited by 11 | Viewed by 8773

Abstract

Behavior mapping (BM) is a spatial data collection technique in which the locational and behavioral information of a user is noted on a plan layout of the studied environment. Among many indoor positioning technologies, we chose Wi-Fi, BLE beacon and ultra-wide band (UWB) [...] Read more.

Behavior mapping (BM) is a spatial data collection technique in which the locational and behavioral information of a user is noted on a plan layout of the studied environment. Among many indoor positioning technologies, we chose Wi-Fi, BLE beacon and ultra-wide band (UWB) sensor technologies for their popularity and investigated their applicability in BM. We tested three technologies for error ranges and found an average error of 1.39 m for Wi-Fi in a 36 m² test area (6 m × 6 m), 0.86 m for the BLE beacon in a 37.44 m² test area (9.6 m × 3.9 m) and 0.24 m for ultra-wide band sensors in a 36 m² test area (6 m × 6 m). We simulated the applicability of these error ranges for real-time locations by using a behavioral dataset collected from an active learning classroom. We used two UWB tags simultaneously by incorporating a custom-designed ceiling system in a new 39.76 m² test area (7.35 m × 5.41 m). We considered 26 observation points and collected data for 180 s for each point (total 4680) with an average error of 0.2072 m for 23 points inside the test area. Finally, we demonstrated the use of ultra-wide band sensor technology for BM. Full article

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

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13 pages, 2427 KiB

Open AccessArticle

Choice of Magnetometers and Gradiometers after Signal Space Separation

by Pilar Garcés^1,2,*

, David López-Sanz^1,2,3

, Fernando Maestú^1,2,3 and Ernesto Pereda^1,4

¹ Laboratory of Cognitive and Computational Neuroscience (UCM-UPM), Centre for Biomedical Technology, 28223 Madrid, Spain

² Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine (CIBER-BBN), Av. Monforte de Lemos 3-5, 28029 Madrid, Spain

³ Department of Basic Psychology II, Faculty of Psychology, Universidad Complutense de Madrid, 28223 Madrid, Spain

⁴ Department of Industrial Engineering, Instituto Universitario de Neurociencia, Universidad de La Laguna, 38205 Tenerife, Spain

Sensors 2017, 17(12), 2926; https://doi.org/10.3390/s17122926 - 16 Dec 2017

Cited by 73 | Viewed by 7592

Abstract

Background: Modern Elekta Neuromag MEG devices include 102 sensor triplets containing one magnetometer and two planar gradiometers. The first processing step is often a signal space separation (SSS), which provides a powerful noise reduction. A question commonly raised by researchers and reviewers relates [...] Read more.

Background: Modern Elekta Neuromag MEG devices include 102 sensor triplets containing one magnetometer and two planar gradiometers. The first processing step is often a signal space separation (SSS), which provides a powerful noise reduction. A question commonly raised by researchers and reviewers relates to which data should be employed in analyses: (1) magnetometers only, (2) gradiometers only, (3) magnetometers and gradiometers together. The MEG community is currently divided with regard to the proper answer. Methods: First, we provide theoretical evidence that both gradiometers and magnetometers result from the backprojection of the same SSS components. Then, we compare resting state and task-related sensor and source estimations from magnetometers and gradiometers in real MEG recordings before and after SSS. Results: SSS introduced a strong increase in the similarity between source time series derived from magnetometers and gradiometers (r² = 0.3–0.8 before SSS and r² > 0.80 after SSS). After SSS, resting state power spectrum and functional connectivity, as well as visual evoked responses, derived from both magnetometers and gradiometers were highly similar (Intraclass Correlation Coefficient > 0.8, r² > 0.8). Conclusions: After SSS, magnetometer and gradiometer data are estimated from a single set of SSS components (usually ≤ 80). Equivalent results can be obtained with both sensor types in typical MEG experiments. Full article

(This article belongs to the Special Issue Advanced Electronic Devices, Circuits, and Signal Processing for Biomedical Sensors Application)

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32 pages, 8245 KiB

Open AccessArticle

A Bluetooth Low Energy Indoor Positioning System with Channel Diversity, Weighted Trilateration and Kalman Filtering

by Vicente Cantón Paterna¹, Anna Calveras Augé^1,*

, Josep Paradells Aspas^1,2 and María Alejandra Pérez Bullones¹

¹ Department of Telematics Engineering, Universitat Politècnica de Catalunya, 08034 Barcelona, Spain

² Fundació i2CAT, 08034 Barcelona, Spain

Sensors 2017, 17(12), 2927; https://doi.org/10.3390/s17122927 - 16 Dec 2017

Cited by 186 | Viewed by 15913

Abstract

Indoor Positioning Systems (IPS) using Bluetooth Low Energy (BLE) technology are currently becoming real and available, which has made them grow in popularity and use. However, there are still plenty of challenges related to this technology, especially in terms of Received Signal Strength [...] Read more.

Indoor Positioning Systems (IPS) using Bluetooth Low Energy (BLE) technology are currently becoming real and available, which has made them grow in popularity and use. However, there are still plenty of challenges related to this technology, especially in terms of Received Signal Strength Indicator (RSSI) fluctuations due to the behaviour of the channels and the multipath effect, that lead to poor precision. In order to mitigate these effects, in this paper we propose and implement a real Indoor Positioning System based on Bluetooth Low Energy, that improves accuracy while reducing power consumption and costs. The three main proposals are: frequency diversity, Kalman filtering and a trilateration method what we have denominated “weighted trilateration”. The analysis of the results proves that all the proposals improve the precision of the system, which goes up to 1.82 m 90% of the time for a device moving in a middle-size room and 0.7 m for static devices. Furthermore, we have proved that the system is scalable and efficient in terms of cost and power consumption. The implemented approach allows using a very simple device (like a SensorTag) on the items to locate. The system enables a very low density of anchor points or references and with a precision better than existing solutions. Full article

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

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22 pages, 2581 KiB

Open AccessArticle

Wireless Concrete Strength Monitoring of Wind Turbine Foundations

by Marcus Perry^1,*

, Grzegorz Fusiek²

, Pawel Niewczas², Tim Rubert² and Jack McAlorum²

¹ Department of Civil & Environmental Engineering, University of Strathclyde, Glasgow G1 1XJ, UK

² Department of Electronic & Electrical Engineering, University of Strathclyde, Glasgow G1 1XQ, UK

Sensors 2017, 17(12), 2928; https://doi.org/10.3390/s17122928 - 16 Dec 2017

Cited by 16 | Viewed by 7557

Abstract

Wind turbine foundations are typically cast in place, leaving the concrete to mature under environmental conditions that vary in time and space. As a result, there is uncertainty around the concrete’s initial performance, and this can encourage both costly over-design and inaccurate prognoses [...] Read more.

Wind turbine foundations are typically cast in place, leaving the concrete to mature under environmental conditions that vary in time and space. As a result, there is uncertainty around the concrete’s initial performance, and this can encourage both costly over-design and inaccurate prognoses of structural health. Here, we demonstrate the field application of a dense, wireless thermocouple network to monitor the strength development of an onshore, reinforced-concrete wind turbine foundation. Up-to-date methods in fly ash concrete strength and maturity modelling are used to estimate the distribution and evolution of foundation strength over 29 days of curing. Strength estimates are verified by core samples, extracted from the foundation base. In addition, an artificial neural network, trained using temperature data, is exploited to demonstrate that distributed concrete strengths can be estimated for foundations using only sparse thermocouple data. Our techniques provide a practical alternative to computational models, and could assist site operators in making more informed decisions about foundation design, construction, operation and maintenance. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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17 pages, 6944 KiB

Open AccessArticle

Vision-Based Target Finding and Inspection of a Ground Target Using a Multirotor UAV System

by Ajmal Hinas^*, Jonathan M. Roberts and Felipe Gonzalez

Robotics and autonomous systems, Queensland University of Technology (QUT), Brisbane City QLD 4000, Australia

Sensors 2017, 17(12), 2929; https://doi.org/10.3390/s17122929 - 17 Dec 2017

Cited by 43 | Viewed by 8668

Abstract

In this paper, a system that uses an algorithm for target detection and navigation and a multirotor Unmanned Aerial Vehicle (UAV) for finding a ground target and inspecting it closely is presented. The system can also be used for accurate and safe delivery [...] Read more.

In this paper, a system that uses an algorithm for target detection and navigation and a multirotor Unmanned Aerial Vehicle (UAV) for finding a ground target and inspecting it closely is presented. The system can also be used for accurate and safe delivery of payloads or spot spraying applications in site-specific crop management. A downward-looking camera attached to a multirotor is used to find the target on the ground. The UAV descends to the target and hovers above the target for a few seconds to inspect the target. A high-level decision algorithm based on an OODA (observe, orient, decide, and act) loop was developed as a solution to address the problem. Navigation of the UAV was achieved by continuously sending local position messages to the autopilot via Mavros. The proposed system performed hovering above the target in three different stages: locate, descend, and hover. The system was tested in multiple trials, in simulations and outdoor tests, from heights of 10 m to 40 m. Results show that the system is highly reliable and robust to sensor errors, drift, and external disturbance. Full article

(This article belongs to the Special Issue UAV or Drones for Remote Sensing Applications)

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18 pages, 19384 KiB

Open AccessArticle

Estimation of the Botanical Composition of Clover-Grass Leys from RGB Images Using Data Simulation and Fully Convolutional Neural Networks

by Søren Skovsen^1,*, Mads Dyrmann¹, Anders Krogh Mortensen², Kim Arild Steen³, Ole Green³, Jørgen Eriksen⁴, René Gislum², Rasmus Nyholm Jørgensen¹ and Henrik Karstoft¹

¹ Department of Engineering, Aarhus University, Finlandsgade 22, 8200 Aarhus N, Denmark

² Department of Agroecology, Aarhus University, Forsøgsvej 1, 4200 Slagelse, Denmark

³ Agro Intelligence ApS, Agro Food Park 13, 8200 Aarhus N, Denmark

⁴ Department of Agroecology, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark

Sensors 2017, 17(12), 2930; https://doi.org/10.3390/s17122930 - 17 Dec 2017

Cited by 39 | Viewed by 9235

Abstract

Optimal fertilization of clover-grass fields relies on knowledge of the clover and grass fractions. This study shows how knowledge can be obtained by analyzing images collected in fields automatically. A fully convolutional neural network was trained to create a pixel-wise classification of clover, [...] Read more.

Optimal fertilization of clover-grass fields relies on knowledge of the clover and grass fractions. This study shows how knowledge can be obtained by analyzing images collected in fields automatically. A fully convolutional neural network was trained to create a pixel-wise classification of clover, grass, and weeds in red, green, and blue (RGB) images of clover-grass mixtures. The estimated clover fractions of the dry matter from the images were found to be highly correlated with the real clover fractions of the dry matter, making this a cheap and non-destructive way of monitoring clover-grass fields. The network was trained solely on simulated top-down images of clover-grass fields. This enables the network to distinguish clover, grass, and weed pixels in real images. The use of simulated images for training reduces the manual labor to a few hours, as compared to more than 3000 h when all the real images are annotated for training. The network was tested on images with varied clover/grass ratios and achieved an overall pixel classification accuracy of 83.4%, while estimating the dry matter clover fraction with a standard deviation of 7.8%. Full article

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

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13 pages, 3615 KiB

Open AccessArticle

Single Interdigital Transducer Approach for Gravimetrical SAW Sensor Applications in Liquid Environments

by Vu Hoa Nguyen¹, Corinna Kaulen²

, Ulrich Simon² and Uwe Schnakenberg^1,*

¹ Institute of Materials in Electrical Engineering 1, RWTH Aachen University, 52074 Aachen, Germany

² Institute of Inorganic Chemistry and JARA-Fundamentals of Future Information Technologies, RWTH Aachen University, 52074 Aachen, Germany

Sensors 2017, 17(12), 2931; https://doi.org/10.3390/s17122931 - 17 Dec 2017

Cited by 11 | Viewed by 7043

Abstract

Surface acoustic wave (SAW) devices are well known for mass-sensitive sensor applications. In biosensing applications, chemical and biochemically evoked binding processes on surfaces are detected in liquid environments using delay line or resonator sensor configurations, preferably in combination with the appropriate microfluidic devices. [...] Read more.

Surface acoustic wave (SAW) devices are well known for mass-sensitive sensor applications. In biosensing applications, chemical and biochemically evoked binding processes on surfaces are detected in liquid environments using delay line or resonator sensor configurations, preferably in combination with the appropriate microfluidic devices. All configurations share the common feature of analyzing the transmission characteristic of the propagating SAW. In this paper, a novel SAW-based impedance sensor type is introduced which uses only one interdigital transducer (IDT), simultaneously as the SAW generator and the sensor element. Here, the input port reflection coefficient S₁₁ is measured at the IDT instead of the commonly used S₂₁ transmission forward gain parameter. Thus, a sharp and distinct peak of the S₁₁ spectrum is obtained, enabling a comfortable direct readout of the sensor signal. Proof of the concept was gained by analyzing the specific binding of the 4-mercaptophenylacetic acid gold nanoparticles (MPA–AuNP) directly to the IDT surface. The corresponding binding kinetic of the MPA–AuNP on the functionalized gold surface has been analyzed and a sensitivity of 7.4 mΩ nM⁻¹ has been determined. Full article

(This article belongs to the Special Issue Surface Acoustic Wave and Bulk Acoustic Wave Sensors)

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11 pages, 3431 KiB

Open AccessArticle

Extraction and Analysis of Respiratory Motion Using Wearable Inertial Sensor System during Trunk Motion

by Apoorva Gaidhani¹, Kee S. Moon^1,*, Yusuf Ozturk², Sung Q. Lee³ and Woosub Youm³

¹ Department of Mechanical Engineering, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA

² Department of Electrical and Computer Engineering, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA

³ Electronics and Telecommunications Research Institute, ICT, 218 Gajeong-ro, Yuseong-gu, Daejeon 34129, Korea

Sensors 2017, 17(12), 2932; https://doi.org/10.3390/s17122932 - 17 Dec 2017

Cited by 37 | Viewed by 6002

Abstract

Respiratory activity is an essential vital sign of life that can indicate changes in typical breathing patterns and irregular body functions such as asthma and panic attacks. Many times, there is a need to monitor breathing activity while performing day-to-day functions such as [...] Read more.

Respiratory activity is an essential vital sign of life that can indicate changes in typical breathing patterns and irregular body functions such as asthma and panic attacks. Many times, there is a need to monitor breathing activity while performing day-to-day functions such as standing, bending, trunk stretching or during yoga exercises. A single IMU (inertial measurement unit) can be used in measuring respiratory motion; however, breathing motion data may be influenced by a body trunk movement that occurs while recording respiratory activity. This research employs a pair of wireless, wearable IMU sensors custom-made by the Department of Electrical Engineering at San Diego State University. After appropriate sensor placement for data collection, this research applies principles of robotics, using the Denavit-Hartenberg convention, to extract relative angular motion between the two sensors. One of the obtained relative joint angles in the “Sagittal” plane predominantly yields respiratory activity. An improvised version of the proposed method and wearable, wireless sensors can be suitable to extract respiratory information while performing sports or exercises, as they do not restrict body motion or the choice of location to gather data. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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26 pages, 6680 KiB

Open AccessArticle

Noisy Ocular Recognition Based on Three Convolutional Neural Networks

by Min Beom Lee, Hyung Gil Hong and Kang Ryoung Park^*

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

Sensors 2017, 17(12), 2933; https://doi.org/10.3390/s17122933 - 17 Dec 2017

Cited by 19 | Viewed by 4558

Abstract

In recent years, the iris recognition system has been gaining increasing acceptance for applications such as access control and smartphone security. When the images of the iris are obtained under unconstrained conditions, an issue of undermined quality is caused by optical and motion [...] Read more.

In recent years, the iris recognition system has been gaining increasing acceptance for applications such as access control and smartphone security. When the images of the iris are obtained under unconstrained conditions, an issue of undermined quality is caused by optical and motion blur, off-angle view (the user’s eyes looking somewhere else, not into the front of the camera), specular reflection (SR) and other factors. Such noisy iris images increase intra-individual variations and, as a result, reduce the accuracy of iris recognition. A typical iris recognition system requires a near-infrared (NIR) illuminator along with an NIR camera, which are larger and more expensive than fingerprint recognition equipment. Hence, many studies have proposed methods of using iris images captured by a visible light camera without the need for an additional illuminator. In this research, we propose a new recognition method for noisy iris and ocular images by using one iris and two periocular regions, based on three convolutional neural networks (CNNs). Experiments were conducted by using the noisy iris challenge evaluation-part II (NICE.II) training dataset (selected from the university of Beira iris (UBIRIS).v2 database), mobile iris challenge evaluation (MICHE) database, and institute of automation of Chinese academy of sciences (CASIA)-Iris-Distance database. As a result, the method proposed by this study outperformed previous methods. Full article

(This article belongs to the Section Physical Sensors)

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17 pages, 2275 KiB

Open AccessArticle

A Quantum Hybrid PSO Combined with Fuzzy k-NN Approach to Feature Selection and Cell Classification in Cervical Cancer Detection

by Abdullah M. Iliyasu^1,2,3,*

and Chastine Fatichah⁴

¹ Electrical Engineering Department, College of Engineering, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia

² School of Computing, Tokyo Institute of Technology, Yokohama 226-8502, Japan

³ School of Computer Science and Technology, Changchun University of Science and Technology, Changchun 130022, China

⁴ Informatics Department, Institut Nepuluh Nopember, ITS Campus, Surabaya 60111, Indonesia

Sensors 2017, 17(12), 2935; https://doi.org/10.3390/s17122935 - 19 Dec 2017

Cited by 43 | Viewed by 5735

Abstract

A quantum hybrid (QH) intelligent approach that blends the adaptive search capability of the quantum-behaved particle swarm optimisation (QPSO) method with the intuitionistic rationality of traditional fuzzy k-nearest neighbours (Fuzzy k-NN) algorithm (known simply as the Q-Fuzzy approach) is proposed for [...] Read more.

A quantum hybrid (QH) intelligent approach that blends the adaptive search capability of the quantum-behaved particle swarm optimisation (QPSO) method with the intuitionistic rationality of traditional fuzzy k-nearest neighbours (Fuzzy k-NN) algorithm (known simply as the Q-Fuzzy approach) is proposed for efficient feature selection and classification of cells in cervical smeared (CS) images. From an initial multitude of 17 features describing the geometry, colour, and texture of the CS images, the QPSO stage of our proposed technique is used to select the best subset features (i.e., global best particles) that represent a pruned down collection of seven features. Using a dataset of almost 1000 images, performance evaluation of our proposed Q-Fuzzy approach assesses the impact of our feature selection on classification accuracy by way of three experimental scenarios that are compared alongside two other approaches: the All-features (i.e., classification without prior feature selection) and another hybrid technique combining the standard PSO algorithm with the Fuzzy k-NN technique (P-Fuzzy approach). In the first and second scenarios, we further divided the assessment criteria in terms of classification accuracy based on the choice of best features and those in terms of the different categories of the cervical cells. In the third scenario, we introduced new QH hybrid techniques, i.e., QPSO combined with other supervised learning methods, and compared the classification accuracy alongside our proposed Q-Fuzzy approach. Furthermore, we employed statistical approaches to establish qualitative agreement with regards to the feature selection in the experimental scenarios 1 and 3. The synergy between the QPSO and Fuzzy k-NN in the proposed Q-Fuzzy approach improves classification accuracy as manifest in the reduction in number cell features, which is crucial for effective cervical cancer detection and diagnosis. Full article

(This article belongs to the Special Issue Sensor Signal and Information Processing)

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18 pages, 10076 KiB

Open AccessArticle

Hazardous Object Detection by Using Kinect Sensor in a Handle-Type Electric Wheelchair

by Jeyeon Kim^1,*, Takaaki Hasegawa²

and Yuta Sakamoto³

¹ Department of Creative Engineering at National Institute of Technology, Tsuruoka College, Tsuruoka, Yamagata 997-8511, Japan

² Division of Mathematics, Electronics and Informatics, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan

³ Takaoka Toko Co., Ltd., Tokyo 110-0005, Japan

Sensors 2017, 17(12), 2936; https://doi.org/10.3390/s17122936 - 18 Dec 2017

Cited by 5 | Viewed by 5744

Abstract

To ensure the safety of a handle-type electric wheelchair (hereinafter, electric wheelchair), this paper describes the applicability of using a Kinect sensor. Ensuring the mobility of elderly people is a particularly important issue to be resolved. An electric wheelchair is useful as a [...] Read more.

To ensure the safety of a handle-type electric wheelchair (hereinafter, electric wheelchair), this paper describes the applicability of using a Kinect sensor. Ensuring the mobility of elderly people is a particularly important issue to be resolved. An electric wheelchair is useful as a means of transportation for elderly people. Considering that the users of electric wheelchairs are elderly people, it is important to ensure the safety of electric wheelchairs at night. To ensure the safety of an electric wheelchair at night, we constructed a hazardous object detection system using commercially available and inexpensive Kinect sensors and examined the applicability of the system. We examined warning timing with consideration to the cognition, judgment, and operation time of elderly people. Based on this, a hazardous object detection area was determined. Furthermore, the detection of static and dynamic hazardous objects was carried out at night and the results showed that the system was able to detect with high accuracy. We also conducted experiments related to dynamic hazardous object detection during daytime. From the above, it showed that the system could be applicable to ensuring the safety of the handle-type electric wheelchair. Full article

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

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17 pages, 8793 KiB

Open AccessArticle

Strain Gauges Based on CVD Graphene Layers and Exfoliated Graphene Nanoplatelets with Enhanced Reproducibility and Scalability for Large Quantities

by Volkan Yokaribas¹, Stefan Wagner²

, Daniel S. Schneider³, Philipp Friebertshäuser¹, Max C. Lemme^2,3 and Claus-Peter Fritzen^1,4,*

¹ Department of Mechanical Engineering, University of Siegen, 57076 Siegen, Germany

² Chair for Electronic Devices, RWTH Aachen University, 52074 Aachen, Germany

³ Advanced Microelectronic Center Aachen (AMICA), AMO GmbH, 52074 Aachen, Germany

⁴ ZESS (Center of Sensor Systems), University of Siegen, 57076 Siegen, Germany

Sensors 2017, 17(12), 2937; https://doi.org/10.3390/s17122937 - 18 Dec 2017

Cited by 27 | Viewed by 9501

Abstract

The two-dimensional material graphene promises a broad variety of sensing activities. Based on its low weight and high versatility, the sensor density can significantly be increased on a structure, which can improve reliability and reduce fluctuation in damage detection strategies such as structural [...] Read more.

The two-dimensional material graphene promises a broad variety of sensing activities. Based on its low weight and high versatility, the sensor density can significantly be increased on a structure, which can improve reliability and reduce fluctuation in damage detection strategies such as structural health monitoring (SHM). Moreover; it initializes the basis of structure–sensor fusion towards self-sensing structures. Strain gauges are extensively used sensors in scientific and industrial applications. In this work, sensing in small strain fields (from −0.1% up to 0.1%) with regard to structural dynamics of a mechanical structure is presented with sensitivities comparable to bulk materials by measuring the inherent piezoresistive effect of graphene grown by chemical vapor deposition (CVD) with a very high aspect ratio of approximately 4.86 × 10⁸. It is demonstrated that the increasing number of graphene layers with CVD graphene plays a key role in reproducible strain gauge application since defects of individual layers may become less important in the current path. This may lead to a more stable response and, thus, resulting in a lower scattering.. Further results demonstrate the piezoresistive effect in a network consisting of liquid exfoliated graphene nanoplatelets (GNP), which result in even higher strain sensitivity and reproducibility. A model-assisted approach provides the main parameters to find an optimum of sensitivity and reproducibility of GNP films. The fabricated GNP strain gauges show a minimal deviation in PRE effect with a GF of approximately 5.6 and predict a linear electromechanical behaviour up to 1% strain. Spray deposition is used to develop a low-cost and scalable manufacturing process for GNP strain gauges. In this context, the challenge of reproducible and reliable manufacturing and operating must be overcome. The developed sensors exhibit strain gauges by considering the significant importance of reproducible sensor performances and open the path for graphene strain gauges for potential usages in science and industry. Full article

(This article belongs to the Special Issue Sensor Technologies for Health Monitoring of Composite Structures)

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16 pages, 5064 KiB

Open AccessArticle

Condition Assessment of Foundation Piles and Utility Poles Based on Guided Wave Propagation Using a Network of Tactile Transducers and Support Vector Machines

by Ulrike Dackermann¹

, Yang Yu^2,*

, Ernst Niederleithinger³

, Jianchun Li² and Herbert Wiggenhauser³

¹ Centre for Infrastructure Engineering and Safety, School of Civil and Environmental Engineering, Faculty of Engineering, University of New South Wales (UNSW), Sydney, NSW 2052, Australia

² Centre for Built Infrastructure Research, School of Civil and Environmental Engineering, Faculty of Engineering and Information Technology, University of Technology, Sydney, NSW 2007, Australia

³ Division 8.2, German Federal Institute for Material Research and Testing (BAM), 12205 Berlin, Germany

Sensors 2017, 17(12), 2938; https://doi.org/10.3390/s17122938 - 18 Dec 2017

Cited by 28 | Viewed by 7540

Abstract

This paper presents a novel non-destructive testing and health monitoring system using a network of tactile transducers and accelerometers for the condition assessment and damage classification of foundation piles and utility poles. While in traditional pile integrity testing an impact hammer with broadband [...] Read more.

This paper presents a novel non-destructive testing and health monitoring system using a network of tactile transducers and accelerometers for the condition assessment and damage classification of foundation piles and utility poles. While in traditional pile integrity testing an impact hammer with broadband frequency excitation is typically used, the proposed testing system utilizes an innovative excitation system based on a network of tactile transducers to induce controlled narrow-band frequency stress waves. Thereby, the simultaneous excitation of multiple stress wave types and modes is avoided (or at least reduced), and targeted wave forms can be generated. The new testing system enables the testing and monitoring of foundation piles and utility poles where the top is inaccessible, making the new testing system suitable, for example, for the condition assessment of pile structures with obstructed heads and of poles with live wires. For system validation, the new system was experimentally tested on nine timber and concrete poles that were inflicted with several types of damage. The tactile transducers were excited with continuous sine wave signals of 1 kHz frequency. Support vector machines were employed together with advanced signal processing algorithms to distinguish recorded stress wave signals from pole structures with different types of damage. The results show that using fast Fourier transform signals, combined with principal component analysis as the input feature vector for support vector machine (SVM) classifiers with different kernel functions, can achieve damage classification with accuracies of 92.5% ± 7.5%. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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20 pages, 7610 KiB

Open AccessArticle

Using the Kalman Algorithm to Correct Data Errors of a 24-Bit Visible Spectrometer

by Son Pham^* and Anh Dinh

Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada

Sensors 2017, 17(12), 2939; https://doi.org/10.3390/s17122939 - 18 Dec 2017

Cited by 3 | Viewed by 3996

Abstract

To reduce cost, increase resolution, and reduce errors due to changing light intensity of the VIS SPEC, a new technique is proposed which applies the Kalman algorithm along with a simple hardware setup and implementation. In real time, the SPEC automatically corrects spectral [...] Read more.

To reduce cost, increase resolution, and reduce errors due to changing light intensity of the VIS SPEC, a new technique is proposed which applies the Kalman algorithm along with a simple hardware setup and implementation. In real time, the SPEC automatically corrects spectral data errors resulting from an unstable light source by adding a photodiode sensor to monitor the changes in light source intensity. The Kalman algorithm is applied on the data to correct the errors. The light intensity instability is one of the sources of error considered in this work. The change in light intensity is due to the remaining lifetime, working time and physical mechanism of the halogen lamp, and/or battery and regulator stability. Coefficients and parameters for the processing are determined from MATLAB simulations based on two real types of datasets, which are mono-changing and multi-changing datasets, collected from the prototype SPEC. From the saved datasets, and based on the Kalman algorithm and other computer algorithms such as divide-and-conquer algorithm and greedy technique, the simulation program implements the search for process noise covariance, the correction function and its correction coefficients. These components, which will be implemented in the processor of the SPEC, Kalman algorithm and the light-source-monitoring sensor are essential to build the Kalman corrector. Through experimental results, the corrector can reduce the total error in the spectra on the order of 10 times; for certain typical local spectral data, it can reduce the error by up to 60 times. The experimental results prove that accuracy of the SPEC increases considerably by using the proposed Kalman corrector in the case of changes in light source intensity. The proposed Kalman technique can be applied to other applications to correct the errors due to slow changes in certain system components. Full article

(This article belongs to the Section Intelligent Sensors)

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14 pages, 5142 KiB

Open AccessArticle

Design and Performance Evaluation of an Electro-Hydraulic Camless Engine Valve Actuator for Future Vehicle Applications

by Kanghyun Nam^1,†, Kwanghyun Cho^2,†, Sang-Shin Park¹ and Seibum B. Choi^3,*

¹ School of Mechanical Engineering, Yeungnam University, 280 Daehak-ro, Gyeongsan 712-749, Korea

² Samsung Electronics Co., Ltd., Gyeonggi-do 443-742, Korea

³ Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea

^† These authors contributed equally to this work.

Sensors 2017, 17(12), 2940; https://doi.org/10.3390/s17122940 - 18 Dec 2017

Cited by 9 | Viewed by 9974

Abstract

This paper details the new design and dynamic simulation of an electro-hydraulic camless engine valve actuator (EH-CEVA) and experimental verification with lift position sensors. In general, camless engine technologies have been known for improving fuel efficiency, enhancing power output, and reducing emissions of [...] Read more.

This paper details the new design and dynamic simulation of an electro-hydraulic camless engine valve actuator (EH-CEVA) and experimental verification with lift position sensors. In general, camless engine technologies have been known for improving fuel efficiency, enhancing power output, and reducing emissions of internal combustion engines. Electro-hydraulic valve actuators are used to eliminate the camshaft of an existing internal combustion engines and used to control the valve timing and valve duration independently. This paper presents novel electro-hydraulic actuator design, dynamic simulations, and analysis based on design specifications required to satisfy the operation performances. An EH-CEVA has initially been designed and modeled by means of a powerful hydraulic simulation software, AMESim, which is useful for the dynamic simulations and analysis of hydraulic systems. Fundamental functions and performances of the EH-CEVA have been validated through comparisons with experimental results obtained in a prototype test bench. Full article

(This article belongs to the Special Issue Mechatronic Systems for Automatic Vehicles)

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9 pages, 5145 KiB

Open AccessArticle

Microstrip Patch Sensor for Salinity Determination

by Kibae Lee¹

, Arshad Hassan^2,3, Chong Hyun Lee^2,* and Jinho Bae²

¹ Research Institute, Kyungwon Co. Ltd., Siheung 15084, Korea

² Department of Ocean System Engineering, Jeju National University, Jeju 690-756, Korea

³ Department of Electrical Engineering, National University of Computer and Emerging Sciences, Foundation for Advancement of Science and Technology (NUCES-FAST), H 11/4, Islamabad 44000, Pakistan

Sensors 2017, 17(12), 2941; https://doi.org/10.3390/s17122941 - 18 Dec 2017

Cited by 34 | Viewed by 5583

Abstract

In this paper, a compact microstrip feed inset patch sensor is proposed for measuring the salinities in seawater. The working principle of the proposed sensor depends on the fact that different salinities in liquid have different relative permittivities and cause different resonance frequencies. [...] Read more.

In this paper, a compact microstrip feed inset patch sensor is proposed for measuring the salinities in seawater. The working principle of the proposed sensor depends on the fact that different salinities in liquid have different relative permittivities and cause different resonance frequencies. The proposed sensor can obtain better sensitivity to salinity changes than common sensors using conductivity change, since the relative permittivity change to salinity is 2.5 times more sensitive than the conductivity change. The patch and ground plane of the proposed sensor are fabricated by conductive copper spray coating on the masks made by 3D printer. The fabricated patch and the ground plane are bonded to a commercial silicon substrate and then attached to 5 mm-high chamber made by 3D printer so that it contains only 1 mL seawater. For easy fabrication and testing, the maximum resonance frequency was selected under 3 GHz and to cover salinities in real seawater, it was assumed that the salinity changes from 20 to 35 ppt. The sensor was designed by the finite element method-based ANSYS high-frequency structure simulator (HFSS), and it can detect the salinity with 0.01 ppt resolution. The designed sensor has a resonance frequency separation of 37.9 kHz and reflection coefficients under −20 dB at the resonant frequencies. The fabricated sensor showed better performance with average frequency separation of 48 kHz and maximum reflection coefficient of −35 dB. By comparing with the existing sensors, the proposed compact and low-cost sensor showed a better detection capability. Therefore, the proposed patch sensor can be utilized in radio frequency (RF) tunable sensors for salinity determination. Full article

(This article belongs to the Section Physical Sensors)

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10 pages, 3137 KiB

Open AccessArticle

Dual-Color Fluorescence Imaging of EpCAM and EGFR in Breast Cancer Cells with a Bull’s Eye-Type Plasmonic Chip

by Shota Izumi¹, Shohei Yamamura², Naoko Hayashi², Mana Toma¹

and Keiko Tawa^1,*

¹ School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyōgo 669-1337, Japan

² Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14, Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan

Sensors 2017, 17(12), 2942; https://doi.org/10.3390/s17122942 - 19 Dec 2017

Cited by 12 | Viewed by 5993

Abstract

Surface plasmon field-enhanced fluorescence microscopic observation of a live breast cancer cell was performed with a plasmonic chip. Two cell lines, MDA-MB-231 and Michigan Cancer Foundation-7 (MCF-7), were selected as breast cancer cells, with two kinds of membrane protein, epithelial cell adhesion molecule [...] Read more.

Surface plasmon field-enhanced fluorescence microscopic observation of a live breast cancer cell was performed with a plasmonic chip. Two cell lines, MDA-MB-231 and Michigan Cancer Foundation-7 (MCF-7), were selected as breast cancer cells, with two kinds of membrane protein, epithelial cell adhesion molecule (EpCAM) and epidermal growth factor receptor (EGFR), observed in both cells. The membrane proteins are surface markers used to differentiate and classify breast cancer cells. EGFR and EpCAM were detected with Alexa Fluor^® 488-labeled anti-EGFR antibody (488-EGFR) and allophycocyanin (APC)-labeled anti-EpCAM antibody (APC-EpCAM), respectively. In MDA-MB231 cells, three-fold plus or minus one and seven-fold plus or minus two brighter fluorescence of 488-EGFR were observed on the 480-nm pitch and the 400-nm pitch compared with that on a glass slide. Results show the 400-nm pitch is useful. Dual-color fluorescence of 488-EGFR and APC-EpCAM in MDA-MB231 was clearly observed with seven-fold plus or minus two and nine-fold plus or minus three, respectively, on the 400-nm pitch pattern of a plasmonic chip. Therefore, the 400-nm pitch contributed to the dual-color fluorescence enhancement for these wavelengths. An optimal grating pitch of a plasmonic chip improved a fluorescence image of membrane proteins with the help of the surface plasmon-enhanced field. Full article

(This article belongs to the Special Issue Dedication to Professor Eiichi Tamiya: Over 30 Years of Outstanding Contributions to the Field of Sensors and Biosensors)

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14 pages, 3411 KiB

Open AccessArticle

Identification of Tequila with an Array of ZnO Thin Films: A Simple and Cost-Effective Method

by Pedro Estanislao Acuña-Avila¹, Raúl Calavia², Enrique Vigueras-Santiago³ and Eduard Llobet^2,*

¹ Universidad Tecnológica de Zinacantepec, Av. Libramiento Universidad 106, San Bartolo el Llano, 51361 Zinacantepec, Estado de México, Mexico

² MINOS-EMaS, Universitat Rovira i Virgili, Avda. Països Catalans, 26, 43007 Tarragona, Spain

³ Laboratorio de Investigación y Desarrollo de Materiales Avanzados (LIDMA), Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón Esquina Paseo Tollocan, Toluca 50200, Estado de México, Mexico

Sensors 2017, 17(12), 2943; https://doi.org/10.3390/s17122943 - 19 Dec 2017

Cited by 12 | Viewed by 5113

Abstract

An array of ZnO thin film sensors was obtained by thermal oxidation of physical vapor deposited thin Zn films. Different conditions of the thermal treatment (duration and temperature) were applied in view of obtaining ZnO sensors with different gas sensing properties. Films having [...] Read more.

An array of ZnO thin film sensors was obtained by thermal oxidation of physical vapor deposited thin Zn films. Different conditions of the thermal treatment (duration and temperature) were applied in view of obtaining ZnO sensors with different gas sensing properties. Films having undergone a long thermal treatment exhibited high responses to low ethanol concentrations, while short thermal treatments generally led to sensors with high ethanol sensitivity. The sensor array was used to distinguish among Tequilas and Agave liquor. Linear discriminant analysis and the multilayer perceptron neural network reached 100% and 86.3% success rates in the discrimination between real Tequila and Agave liquor and in the identification of Tequila brands, respectively. These results are promising for the development of an inexpensive tool offering low complexity and cost of analysis for detecting fraud in spirits. Full article

(This article belongs to the Section Chemical Sensors)

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16 pages, 5020 KiB

Open AccessArticle

Sensitivity Analysis of Different Shapes of a Plastic Optical Fiber-Based Immunosensor for Escherichia coli: Simulation and Experimental Results

by Domingos M. C. Rodrigues¹, Rafaela N. Lopes¹, Marcos A. R. Franco², Marcelo M. Werneck^1,*,†

and Regina C. S. B. Allil¹

¹ Federal University of Rio de Janeiro (UFRJ), Electrical Engineering Program, Photonics and Instrumentation Laboratory, Rio de Janeiro 21.941-901, Brazil

² Institute of Advanced Studies (IEAv), S. José dos Campos 12.228-001, Brazil

^† Also with Nanotechnology Engineering Program (UFRJ).

Sensors 2017, 17(12), 2944; https://doi.org/10.3390/s17122944 - 19 Dec 2017

Cited by 21 | Viewed by 5607

Abstract

Conventional pathogen detection methods require trained personnel, specialized laboratories and can take days to provide a result. Thus, portable biosensors with rapid detection response are vital for the current needs for in-loco quality assays. In this work the authors analyze the characteristics of [...] Read more.

Conventional pathogen detection methods require trained personnel, specialized laboratories and can take days to provide a result. Thus, portable biosensors with rapid detection response are vital for the current needs for in-loco quality assays. In this work the authors analyze the characteristics of an immunosensor based on the evanescent field in plastic optical fibers with macro curvature by comparing experimental with simulated results. The work studies different shapes of evanescent-wave based fiber optic sensors, adopting a computational modeling to evaluate the probes with the best sensitivity. The simulation showed that for a U-Shaped sensor, the best results can be achieved with a sensor of 980 µm diameter by 5.0 mm in curvature for refractive index sensing, whereas the meander-shaped sensor with 250 μm in diameter with radius of curvature of 1.5 mm, showed better sensitivity for either bacteria and refractive index (RI) sensing. Then, an immunosensor was developed, firstly to measure refractive index and after that, functionalized to detect Escherichia coli. Based on the results with the simulation, we conducted studies with a real sensor for RI measurements and for Escherichia coli detection aiming to establish the best diameter and curvature radius in order to obtain an optimized sensor. On comparing the experimental results with predictions made from the modelling, good agreements were obtained. The simulations performed allowed the evaluation of new geometric configurations of biosensors that can be easily constructed and that promise improved sensitivity. Full article

(This article belongs to the Special Issue Nanostructured Hybrid Materials Based Opto-Electronics Sensors)

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25 pages, 2275 KiB

Open AccessArticle

Pre-Scheduled and Self Organized Sleep-Scheduling Algorithms for Efficient K-Coverage in Wireless Sensor Networks

by Prasan Kumar Sahoo^1,2

, Hiren Kumar Thakkar¹

and I-Shyan Hwang^3,*

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

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

³ Department of Computer Science and Engineering, Yuan Ze University, Chung-Li District, Taoyuan 32003, Taiwan

Sensors 2017, 17(12), 2945; https://doi.org/10.3390/s17122945 - 19 Dec 2017

Cited by 11 | Viewed by 3944

Abstract

The K-coverage configuration that guarantees coverage of each location by at least K sensors is highly popular and is extensively used to monitor diversified applications in wireless sensor networks. Long network lifetime and high detection quality are the essentials of such K [...] Read more.

The K-coverage configuration that guarantees coverage of each location by at least K sensors is highly popular and is extensively used to monitor diversified applications in wireless sensor networks. Long network lifetime and high detection quality are the essentials of such K-covered sleep-scheduling algorithms. However, the existing sleep-scheduling algorithms either cause high cost or cannot preserve the detection quality effectively. In this paper, the Pre-Scheduling-based K-coverage Group Scheduling (PSKGS) and Self-Organized K-coverage Scheduling (SKS) algorithms are proposed to settle the problems in the existing sleep-scheduling algorithms. Simulation results show that our pre-scheduled-based KGS approach enhances the detection quality and network lifetime, whereas the self-organized-based SKS algorithm minimizes the computation and communication cost of the nodes and thereby is energy efficient. Besides, SKS outperforms PSKGS in terms of network lifetime and detection quality as it is self-organized. Full article

(This article belongs to the Section Sensor Networks)

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20 pages, 980 KiB

Open AccessArticle

An Enhanced Three-Factor User Authentication Scheme Using Elliptic Curve Cryptosystem for Wireless Sensor Networks

by Chenyu Wang

, Guoai Xu^* and Jing Sun

New Research Activities Darparment, Beijing University of Posts and Telecommunications, Haidian District, Beijing 100876, China

Sensors 2017, 17(12), 2946; https://doi.org/10.3390/s17122946 - 19 Dec 2017

Cited by 71 | Viewed by 6797

Abstract

As an essential part of Internet of Things (IoT), wireless sensor networks (WSNs) have touched every aspect of our lives, such as health monitoring, environmental monitoring and traffic monitoring. However, due to its openness, wireless sensor networks are vulnerable to various security threats. [...] Read more.

As an essential part of Internet of Things (IoT), wireless sensor networks (WSNs) have touched every aspect of our lives, such as health monitoring, environmental monitoring and traffic monitoring. However, due to its openness, wireless sensor networks are vulnerable to various security threats. User authentication, as the first fundamental step to protect systems from various attacks, has attracted much attention. Numerous user authentication protocols armed with formal proof are springing up. Recently, two biometric-based schemes were proposed with confidence to be resistant to the known attacks including offline dictionary attack, impersonation attack and so on. However, after a scrutinization of these two schemes, we found them not secure enough as claimed, and then demonstrated that these schemes suffer from various attacks, such as offline dictionary attack, impersonation attack, no user anonymity, no forward secrecy, etc. Furthermore, we proposed an enhanced scheme to overcome the identified weaknesses, and proved its security via Burrows–Abadi–Needham (BAN) logic and the heuristic analysis. Finally, we compared our scheme with other related schemes, and the results showed the superiority of our scheme. Full article

(This article belongs to the Special Issue Security, Trust and Privacy for Sensor Networks)

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21 pages, 4401 KiB

Open AccessArticle

Blind Compensation of I/Q Impairments in Wireless Transceivers

by Mohsin Aziz^*, Fadhel M. Ghannouchi and Mohamed Helaoui

iRadio Lab, Department of Electrical and Computer Engineering, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada

Sensors 2017, 17(12), 2948; https://doi.org/10.3390/s17122948 - 19 Dec 2017

Cited by 13 | Viewed by 5556

Abstract

The majority of techniques that deal with the mitigation of in-phase and quadrature-phase (I/Q) imbalance at the transmitter (pre-compensation) require long training sequences, reducing the throughput of the system. These techniques also require a feedback path, which adds more [...] Read more.

The majority of techniques that deal with the mitigation of in-phase and quadrature-phase (I/Q) imbalance at the transmitter (pre-compensation) require long training sequences, reducing the throughput of the system. These techniques also require a feedback path, which adds more complexity and cost to the transmitter architecture. Blind estimation techniques are attractive for avoiding the use of long training sequences. In this paper, we propose a blind frequency-independent I/Q imbalance compensation method based on the maximum likelihood (ML) estimation of the imbalance parameters of a transceiver. A closed-form joint probability density function (PDF) for the imbalanced I and Q signals is derived and validated. ML estimation is then used to estimate the imbalance parameters using the derived joint PDF of the output I and Q signals. Various figures of merit have been used to evaluate the efficacy of the proposed approach using extensive computer simulations and measurements. Additionally, the bit error rate curves show the effectiveness of the proposed method in the presence of the wireless channel and Additive White Gaussian Noise. Real-world experimental results show an image rejection of greater than 30 dB as compared to the uncompensated system. This method has also been found to be robust in the presence of practical system impairments, such as time and phase delay mismatches. Full article

(This article belongs to the Special Issue Recent Advances in Front-End Designs for Sensors and Wireless Networks)

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21 pages, 6832 KiB

Open AccessFeature PaperArticle

Integrity Testing of Pile Cover Using Distributed Fibre Optic Sensing

by Yi Rui¹, Cedric Kechavarzi¹, Frank O’Leary², Chris Barker², Duncan Nicholson² and Kenichi Soga^3,*

¹ Centre for Smart Infrastructure & Construction, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK

² Arup Group Limited, London W1T 4BQ, UK

³ Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1234, USA

Sensors 2017, 17(12), 2949; https://doi.org/10.3390/s17122949 - 19 Dec 2017

Cited by 44 | Viewed by 10276

Abstract

The integrity of cast-in-place foundation piles is a major concern in geotechnical engineering. In this study, distributed fibre optic sensing (DFOS) cables, embedded in a pile during concreting, are used to measure the changes in concrete curing temperature profile to infer concrete cover [...] Read more.

The integrity of cast-in-place foundation piles is a major concern in geotechnical engineering. In this study, distributed fibre optic sensing (DFOS) cables, embedded in a pile during concreting, are used to measure the changes in concrete curing temperature profile to infer concrete cover thickness through modelling of heat transfer processes within the concrete and adjacent ground. A field trial was conducted at a high-rise building construction site in London during the construction of a 51 m long test pile. DFOS cables were attached to the reinforcement cage of the pile at four different axial directions to obtain distributed temperature change data along the pile. The monitoring data shows a clear development of concrete hydration temperature with time and the pattern of the change varies due to small changes in concrete cover. A one-dimensional axisymmetric heat transfer finite element (FE) model is used to estimate the pile geometry with depth by back analysing the DFOS data. The results show that the estimated pile diameter varies with depth in the range between 1.40 and 1.56 m for this instrumented pile. This average pile diameter profile compares well to that obtained with the standard Thermal Integrity Profiling (TIP) method. A parametric study is conducted to examine the sensitivity of concrete and soil thermal properties on estimating the pile geometry. Full article

(This article belongs to the Special Issue Sensors and Sensor Networks for Structural Health Monitoring)

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15 pages, 3650 KiB

Open AccessArticle

Investigation of Wavenumber Domain Imaging Algorithm for Ground-Based Arc Array SAR

by Zengshu Huang¹, Jinping Sun^1,*

, Weixian Tan², Pingping Huang²

and Kuoye Han³

¹ Electronics & Information Engineering, Beihang University, Beijing 100191, China

² College of Information Engineering, Inner Mongolia University of Technology, Hohhot 010051, China

³ Information Science Academy, China Electronics Technology Group Corporation, Beijing 100098, China

Sensors 2017, 17(12), 2950; https://doi.org/10.3390/s17122950 - 19 Dec 2017

Cited by 19 | Viewed by 5352

Abstract

Ground-based synthetic aperture radar (GB-SAR) has become an important technique for remote sensing deformation monitoring. However, most of the existing GB-SAR systems realize synthetic aperture by exploiting two closely spaced horn antennas to move along a linear rail. In order to obtain higher [...] Read more.

Ground-based synthetic aperture radar (GB-SAR) has become an important technique for remote sensing deformation monitoring. However, most of the existing GB-SAR systems realize synthetic aperture by exploiting two closely spaced horn antennas to move along a linear rail. In order to obtain higher data acquisition efficiency and a wider view angle, we introduce arc antenna array technology into the GB-SAR system, which realizes a novel kind of system: ground-based arc array SAR (GB-AA-SAR). In this paper, we analyze arc observation geometry and derive analytic expressions of sampling criteria. Then, we propose a novel wavenumber domain imaging algorithm for GB-AA-SAR, which can achieve high image reconstruction precision through numerical solutions in the wavenumber domain. The proposed algorithm can be applied in wide azimuth view angle scenarios, and the problem of azimuth mismatch caused by distance approximation in arc geometric efficient omega-k imaging can be solved successfully. Finally, we analyze the two-dimensional (2D) spatial resolution of GB-AA-SAR, and verify the effectiveness of the proposed algorithm through numerical simulation experiments. Full article

(This article belongs to the Special Issue Synthetic Aperture Radar (SAR) Technology: New Perspectives Offered by New-Generation and Forthcoming SAR Sensors)

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7 pages, 3981 KiB

Open AccessArticle

3D-Printed Detector Band for Magnetic Off-Plane Flux Measurements in Laminated Machine Cores

by Georgi Shilyashki^*

, Helmut Pfützner, Martin Palkovits, Andreas Windischhofer and Markus Giefing

Institute of Electrodynamics, Microwave and Circuit Engineering, TU Wien, Gußhausstraße 25/354, 1040 Vienna, Austria

Sensors 2017, 17(12), 2953; https://doi.org/10.3390/s17122953 - 19 Dec 2017

Cited by 7 | Viewed by 4595

Abstract

Laminated soft magnetic cores of transformers, rotating machines etc. may exhibit complex 3D flux distributions with pronounced normal fluxes (off-plane fluxes), perpendicular to the plane of magnetization. As recent research activities have shown, detections of off-plane fluxes tend to be essential for the [...] Read more.

Laminated soft magnetic cores of transformers, rotating machines etc. may exhibit complex 3D flux distributions with pronounced normal fluxes (off-plane fluxes), perpendicular to the plane of magnetization. As recent research activities have shown, detections of off-plane fluxes tend to be essential for the optimization of core performances aiming at a reduction of core losses and of audible noise. Conventional sensors for off-plane flux measurements tend to be either of high thickness, influencing the measured fluxes significantly, or require laborious preparations. In the current work, thin novel detector bands for effective and simple off-plane flux detections in laminated machine cores were manufactured. They are printed in an automatic way by an in-house developed 3D/2D assembler. The latter enables a unique combination of conductive and non-conductive materials. The detector bands were effectively tested in the interior of a two-package, three-phase model transformer core. They proved to be mechanically resilient, even for strong clamping of the core. Full article

(This article belongs to the Special Issue Magnetic Sensors and Their Applications)

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10 pages, 1824 KiB

Open AccessArticle

Sulfophenyl-Functionalized Reduced Graphene Oxide Networks on Electrospun 3D Scaffold for Ultrasensitive NO₂ Gas Sensor

by Bin Zou¹, Yunlong Guo^1,2, Nannan Shen², Anshan Xiao¹, Mingjun Li¹, Liang Zhu^1,*, Pengbo Wan² and Xiaoming Sun^2,*

¹ State Key Laboratory of Safety and Control for Chemicals, SINOPEC Research Institute of Safety Engineering, Qingdao 266101, China

² State Key Laboratory of Chemical Resource Engineering, P.O. Box 98, Beijing University of Chemical Technology, Beijing 100029, China

Sensors 2017, 17(12), 2954; https://doi.org/10.3390/s17122954 - 19 Dec 2017

Cited by 19 | Viewed by 6811

Abstract

Ultrasensitive room temperature real-time NO₂ sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO₂ gas sensors with highly operated temperatures (200–600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or [...] Read more.

Ultrasensitive room temperature real-time NO₂ sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO₂ gas sensors with highly operated temperatures (200–600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or inter-finger probes. Herein, we report the functionalized graphene network film sensors assembled on an electrospun three-dimensional (3D) nanonetwork skeleton for ultrasensitive NO₂ sensing. The functional 3D scaffold was prepared by electrospinning interconnected polyacrylonitrile (PAN) nanofibers onto a nylon window screen to provide a 3D nanonetwork skeleton. Then, the sulfophenyl-functionalized reduced graphene oxide (SFRGO) was assembled on the electrospun 3D nanonetwork skeleton to form SFRGO network films. The assembled functionalized graphene network film sensors exhibit excellent NO₂ sensing performance (10 ppb to 20 ppm) at room temperature, reliable reversibility, good selectivity, and better sensing cycle stability. These improvements can be ascribed to the functionalization of graphene with electron-withdrawing sulfophenyl groups, the high surface-to-volume ratio, and the effective sensing channels from SFRGO wrapping onto the interconnected 3D scaffold. The SFRGO network-sensing film has the advantages of simple preparation, low cost, good processability, and ultrasensitive NO₂ sensing, all advantages that can be utilized for potential integration into smart windows and wearable electronic devices for real-time household gas sensors. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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12 pages, 3300 KiB

Open AccessArticle

Anti-Runaway Prevention System with Wireless Sensors for Intelligent Track Skates at Railway Stations

by Chaozhe Jiang^1,2, Yibo Xu³, Chao Wen^1,2,*

and Dilin Chen⁴

¹ National United Engineering Laboratory of Integrated and Intelligent Transportation, Chengdu 610031, China

² Railway Research Center, University of Waterloo, Waterloo, ON N2L 3G1, Canada

³ Cloud-Guizhou Big Data Science Application Research Center, Guiyang 550081, Guizhou, China

⁴ Department of Industrial and Enterprise System Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

Sensors 2017, 17(12), 2955; https://doi.org/10.3390/s17122955 - 19 Dec 2017

Cited by 4 | Viewed by 5197

Abstract

Anti-runaway prevention of rolling stocks at a railway station is essential in railway safety management. The traditional track skates for anti-runaway prevention of rolling stocks have some disadvantages since they are operated and monitored completely manually. This paper describes an anti-runaway prevention system [...] Read more.

Anti-runaway prevention of rolling stocks at a railway station is essential in railway safety management. The traditional track skates for anti-runaway prevention of rolling stocks have some disadvantages since they are operated and monitored completely manually. This paper describes an anti-runaway prevention system (ARPS) based on intelligent track skates equipped with sensors and real-time monitoring and management system. This system, which has been updated from the traditional track skates, comprises four parts: intelligent track skates, a signal reader, a database station, and a monitoring system. This system can monitor the real-time situation of track skates without changing their workflow for anti-runaway prevention, and thus realize the integration of anti-runaway prevention information management. This system was successfully tested and practiced at Sunjia station in Harbin Railway Bureau in 2014, and the results confirmed that the system showed 100% accuracy in reflecting the usage status of the track skates. The system could meet practical demands, as it is highly reliable and supports long-distance communication. Full article

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

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18 pages, 7375 KiB

Open AccessArticle

Enhancing Time Synchronization Support in Wireless Sensor Networks

by Leandro Tavares Bruscato¹, Tales Heimfarth² and Edison Pignaton de Freitas^1,*

¹ Electrical Engineering Graduate Program, Federal University of Rio Grande do Sul, Porto Alegre 90035-190, Brazil

² Computer Science Department, Federal University of Lavras, Lavras 37200-000, Brazil

Sensors 2017, 17(12), 2956; https://doi.org/10.3390/s17122956 - 20 Dec 2017

Cited by 32 | Viewed by 6521

Abstract

With the emerging Internet of Things (IoT) technology becoming reality, a number of applications are being proposed. Several of these applications are highly dependent on wireless sensor networks (WSN) to acquire data from the surrounding environment. In order to be really useful for [...] Read more.

With the emerging Internet of Things (IoT) technology becoming reality, a number of applications are being proposed. Several of these applications are highly dependent on wireless sensor networks (WSN) to acquire data from the surrounding environment. In order to be really useful for most of applications, the acquired data must be coherent in terms of the time in which they are acquired, which implies that the entire sensor network presents a certain level of time synchronization. Moreover, to efficiently exchange and forward data, many communication protocols used in WSN rely also on time synchronization among the sensor nodes. Observing the importance in complying with this need for time synchronization, this work focuses on the second synchronization problem, proposing, implementing and testing a time synchronization service for low-power WSN using low frequency real-time clocks in each node. To implement this service, three algorithms based on different strategies are proposed: one based on an auto-correction approach, the second based on a prediction mechanism, while the third uses an analytical correction mechanism. Their goal is the same, i.e., to make the clocks of the sensor nodes converge as quickly as possible and then to keep them most similar as possible. This goal comes along with the requirement to keep low energy consumption. Differently from other works in the literature, the proposal here is independent of any specific protocol, i.e., it may be adapted to be used in different protocols. Moreover, it explores the minimum number of synchronization messages by means of a smart clock update strategy, allowing the trade-off between the desired level of synchronization and the associated energy consumption. Experimental results, which includes data acquired from simulations and testbed deployments, provide evidence of the success in meeting this goal, as well as providing means to compare these three approaches considering the best synchronization results and their costs in terms of energy consumption. Full article

(This article belongs to the Special Issue Internet of Things and Ubiquitous Sensing)

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16 pages, 3695 KiB

Open AccessArticle

An Architecture Providing Depolarization Ratio Capability for a Multi-Wavelength Raman Lidar: Implementation and First Measurements

by Alejandro Rodríguez-Gómez^1,*

, Michaël Sicard^1,2

, María-José Granados-Muñoz¹, Enis Ben Chahed^1,3, Constantino Muñoz-Porcar¹, Rubén Barragán^1,2, Adolfo Comerón¹

, Francesc Rocadenbosch^1,2 and Eric Vidal⁴

¹ CommSensLab, Department of Signal Theory and Communications, Universitat Politècnica de Catalunya (BarcelonaTech-UPC), 08034 Barcelona, Spain

² Space Sciences and Technologies-Research Center for Aeronautics and Space/Catalan Institute for Space Studies (CTE-CRAE/IEEC), BarcelonaTech University (UPC), 08034 Barcelona, Spain

³ Politecnico di Torino, 10129 Torino, Italy

⁴ UTC Fire & Security España SL, 08950 Esplugues de Llobregat, Spain

Sensors 2017, 17(12), 2957; https://doi.org/10.3390/s17122957 - 20 Dec 2017

Cited by 9 | Viewed by 5161

Abstract

A new architecture for the measurement of depolarization produced by atmospheric aerosols with a Raman lidar is presented. The system uses two different telescopes: one for depolarization measurements and another for total-power measurements. The system architecture and principle of operation are described. The [...] Read more.

A new architecture for the measurement of depolarization produced by atmospheric aerosols with a Raman lidar is presented. The system uses two different telescopes: one for depolarization measurements and another for total-power measurements. The system architecture and principle of operation are described. The first experimental results are also presented, corresponding to a collection of atmospheric conditions over the city of Barcelona. Full article

(This article belongs to the Section Remote Sensors)

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19 pages, 1170 KiB

Open AccessArticle

Optimal Rate Schedules with Data Sharing in Energy Harvesting Communication Systems

by Weiwei Wu¹, Huafan Li¹, Feng Shan^1,* and Yingchao Zhao²

¹ School of Computer Science and Engineering, Southeast University, Nanjing 210018, China

² School of Computing and Information Sciences, Caritas Institute of Higher Education, Hong Kong 999077, China

Sensors 2017, 17(12), 2958; https://doi.org/10.3390/s17122958 - 20 Dec 2017

Cited by 1 | Viewed by 3943

Abstract

Despite the abundant research on energy-efficient rate scheduling polices in energy harvesting communication systems, few works have exploited data sharing among multiple applications to further enhance the energy utilization efficiency, considering that the harvested energy from environments is limited and unstable. In this [...] Read more.

Despite the abundant research on energy-efficient rate scheduling polices in energy harvesting communication systems, few works have exploited data sharing among multiple applications to further enhance the energy utilization efficiency, considering that the harvested energy from environments is limited and unstable. In this paper, to overcome the energy shortage of wireless devices at transmitting data to a platform running multiple applications/requesters, we design rate scheduling policies to respond to data requests as soon as possible by encouraging data sharing among data requests and reducing the redundancy. We formulate the problem as a transmission completion time minimization problem under constraints of dynamical data requests and energy arrivals. We develop offline and online algorithms to solve this problem. For the offline setting, we discover the relationship between two problems: the completion time minimization problem and the energy consumption minimization problem with a given completion time. We first derive the optimal algorithm for the min-energy problem and then adopt it as a building block to compute the optimal solution for the min-completion-time problem. For the online setting without future information, we develop an event-driven online algorithm to complete the transmission as soon as possible. Simulation results validate the efficiency of the proposed algorithm. Full article

(This article belongs to the Section Sensor Networks)

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18 pages, 5217 KiB

Open AccessArticle

A Large-Scale Multi-Hop Localization Algorithm Based on Regularized Extreme Learning for Wireless Networks

by Wei Zheng¹, Xiaoyong Yan^2,*, Wei Zhao¹ and Chengshan Qian³

¹ School of Computer Engineering, Jinling Institute of Technology, Nanjing, 211169, China

² School of Modern Post & Institute of Modern Posts, Nanjing University of Posts and Telecommunications, Nanjing 210003, China

³ School of Computer & Software, Nanjing University of Information Science and Technology, Nanjing 210044, China

Sensors 2017, 17(12), 2959; https://doi.org/10.3390/s17122959 - 20 Dec 2017

Cited by 9 | Viewed by 4849

Abstract

A novel large-scale multi-hop localization algorithm based on regularized extreme learning is proposed in this paper. The large-scale multi-hop localization problem is formulated as a learning problem. Unlike other similar localization algorithms, the proposed algorithm overcomes the shortcoming of the traditional algorithms which [...] Read more.

A novel large-scale multi-hop localization algorithm based on regularized extreme learning is proposed in this paper. The large-scale multi-hop localization problem is formulated as a learning problem. Unlike other similar localization algorithms, the proposed algorithm overcomes the shortcoming of the traditional algorithms which are only applicable to an isotropic network, therefore has a strong adaptability to the complex deployment environment. The proposed algorithm is composed of three stages: data acquisition, modeling and location estimation. In data acquisition stage, the training information between nodes of the given network is collected. In modeling stage, the model among the hop-counts and the physical distances between nodes is constructed using regularized extreme learning. In location estimation stage, each node finds its specific location in a distributed manner. Theoretical analysis and several experiments show that the proposed algorithm can adapt to the different topological environments with low computational cost. Furthermore, high accuracy can be achieved by this method without setting complex parameters. Full article

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

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13 pages, 4388 KiB

Open AccessArticle

Remotely Exploring Deeper-Into-Matter by Non-Contact Detection of Audible Transients Excited by Laser Radiation

by Javier Moros^*

, Inmaculada Gaona and J. Javier Laserna

UMALaserlab, Departamento de Química Analítica, Facultad de Ciencias, Universidad de Málaga, Jiménez Fraud 4th, 29010 Málaga, Spain

Sensors 2017, 17(12), 2960; https://doi.org/10.3390/s17122960 - 20 Dec 2017

Cited by 2 | Viewed by 4473

Abstract

An acoustic spectroscopic approach to detect contents within different packaging, with substantially wider applicability than other currently available subsurface spectroscopies, is presented. A frequency-doubled Nd:YAG (neodymium-doped yttrium aluminum garnet) pulsed laser (13 ns pulse length) operated at 1 Hz was used to generate [...] Read more.

An acoustic spectroscopic approach to detect contents within different packaging, with substantially wider applicability than other currently available subsurface spectroscopies, is presented. A frequency-doubled Nd:YAG (neodymium-doped yttrium aluminum garnet) pulsed laser (13 ns pulse length) operated at 1 Hz was used to generate the sound field of a two-component system at a distance of 50 cm. The acoustic emission was captured using a unidirectional microphone and analyzed in the frequency domain. The focused laser pulse hitting the system, with intensity above that necessary to ablate the irradiated surface, transferred an impulsive force which led the structure to vibrate. Acoustic airborne transients were directly radiated by the vibrating elastic structure of the outer component that excited the surrounding air in contact with. However, under boundary conditions, sound field is modulated by the inner component that modified the dynamical integrity of the system. Thus, the resulting frequency spectra are useful indicators of the concealed content that influences the contributions originating from the wall of the container. High-quality acoustic spectra could be recorded from a gas (air), liquid (water), and solid (sand) placed inside opaque chemical-resistant polypropylene and stainless steel sample containers. Discussion about effects of laser excitation energy and sampling position on the acoustic emission events is reported. Acoustic spectroscopy may complement the other subsurface alternative spectroscopies, severely limited by their inherent optical requirements for numerous detection scenarios. Full article

(This article belongs to the Special Issue Spectroscopy Based Sensors)

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13 pages, 2112 KiB

Open AccessArticle

Location Accuracy of INS/Gravity-Integrated Navigation System on the Basis of Ocean Experiment and Simulation

by Hubiao Wang¹, Lin Wu¹

, Hua Chai¹, Lifeng Bao¹ and Yong Wang^1,2,*

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

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

Sensors 2017, 17(12), 2961; https://doi.org/10.3390/s17122961 - 20 Dec 2017

Cited by 23 | Viewed by 5496

Abstract

An experiment comparing the location accuracy of gravity matching-aided navigation in the ocean and simulation is very important to evaluate the feasibility and the performance of an INS/gravity-integrated navigation system (IGNS) in underwater navigation. Based on a 1′ × 1′ marine gravity anomaly [...] Read more.

An experiment comparing the location accuracy of gravity matching-aided navigation in the ocean and simulation is very important to evaluate the feasibility and the performance of an INS/gravity-integrated navigation system (IGNS) in underwater navigation. Based on a 1′ × 1′ marine gravity anomaly reference map and multi-model adaptive Kalman filtering algorithm, a matching location experiment of IGNS was conducted using data obtained using marine gravimeter. The location accuracy under actual ocean conditions was 2.83 nautical miles (n miles). Several groups of simulated data of marine gravity anomalies were obtained by establishing normally distributed random error

N (u, σ^{2})

with varying mean

u

and noise variance

σ^{2}

. Thereafter, the matching location of IGNS was simulated. The results show that the changes in

u

had little effect on the location accuracy. However, an increase in

σ^{2}

resulted in a significant decrease in the location accuracy. A comparison between the actual ocean experiment and the simulation along the same route demonstrated the effectiveness of the proposed simulation method and quantitative analysis results. In addition, given the gravimeter (1–2 mGal accuracy) and the reference map (resolution 1′ × 1′; accuracy 3–8 mGal), location accuracy of IGNS was up to reach ~1.0–3.0 n miles in the South China Sea. Full article

(This article belongs to the Special Issue Inertial Sensors for Positioning and Navigation)

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7 pages, 1568 KiB

Open AccessArticle

Quantitative and Sensitive Detection of Chloramphenicol by Surface-Enhanced Raman Scattering

by Yufeng Ding^1,2, Xin Zhang^1,2,*

, Hongjun Yin^1,2, Qingyun Meng^1,2, Yongmei Zhao³, Luo Liu¹, Zhenglong Wu⁴ and Haijun Xu^1,2,*

¹ Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Beijing 100029, China

² College of Science, Beijing University of Chemical Technology, Beijing 100029, China

³ Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China

⁴ Analytical and Testing Center, Beijing Normal University, Beijing 100875, China

Sensors 2017, 17(12), 2962; https://doi.org/10.3390/s17122962 - 20 Dec 2017

Cited by 37 | Viewed by 6155

Abstract

We used surface-enhanced Raman scattering (SERS) for the quantitative and sensitive detection of chloramphenicol (CAP). Using 30 nm colloidal Au nanoparticles (NPs), a low detection limit for CAP of 10⁻⁸ M was obtained. The characteristic Raman peak of CAP centered at 1344 [...] Read more.

We used surface-enhanced Raman scattering (SERS) for the quantitative and sensitive detection of chloramphenicol (CAP). Using 30 nm colloidal Au nanoparticles (NPs), a low detection limit for CAP of 10⁻⁸ M was obtained. The characteristic Raman peak of CAP centered at 1344 cm⁻¹ was used for the rapid quantitative detection of CAP in three different types of CAP eye drops, and the accuracy of the measurement result was verified by high-performance liquid chromatography (HPLC). The experimental results reveal that the SERS technique based on colloidal Au NPs is accurate and sensitive, and can be used for the rapid detection of various antibiotics. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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23 pages, 14869 KiB

Open AccessArticle

Out-of-Focus Projector Calibration Method with Distortion Correction on the Projection Plane in the Structured Light Three-Dimensional Measurement System

by Jiarui Zhang^*, Yingjie Zhang and Bo Chen

School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China

Sensors 2017, 17(12), 2963; https://doi.org/10.3390/s17122963 - 20 Dec 2017

Cited by 6 | Viewed by 9625

Abstract

The three-dimensional measurement system with a binary defocusing technique is widely applied in diverse fields. The measurement accuracy is mainly determined by out-of-focus projector calibration accuracy. In this paper, a high-precision out-of-focus projector calibration method that is based on distortion correction on the [...] Read more.

The three-dimensional measurement system with a binary defocusing technique is widely applied in diverse fields. The measurement accuracy is mainly determined by out-of-focus projector calibration accuracy. In this paper, a high-precision out-of-focus projector calibration method that is based on distortion correction on the projection plane and nonlinear optimization algorithm is proposed. To this end, the paper experimentally presents the principle that the projector has noticeable distortions outside its focus plane. In terms of this principle, the proposed method uses a high-order radial and tangential lens distortion representation on the projection plane to correct the calibration residuals caused by projection distortion. The final accuracy parameters of out-of-focus projector were obtained using a nonlinear optimization algorithm with good initial values, which were provided by coarsely calibrating the parameters of the out-of-focus projector on the focal and projection planes. Finally, the experimental results demonstrated that the proposed method can accuracy calibrate an out-of-focus projector, regardless of the amount of defocusing. Full article

(This article belongs to the Section Physical Sensors)

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Review

Jump to: Research, Other

21 pages, 325 KiB

Open AccessReview

A Survey of Recent Advances in Particle Filters and Remaining Challenges for Multitarget Tracking

by Xuedong Wang¹, Tiancheng Li^2,*

, Shudong Sun¹ and Juan M. Corchado²

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

² BISITE Research Group, School of Science, University of Salamanca, 37008 Salamanca, Spain

Sensors 2017, 17(12), 2707; https://doi.org/10.3390/s17122707 - 23 Nov 2017

Cited by 133 | Viewed by 10547

Abstract

We review some advances of the particle filtering (PF) algorithm that have been achieved in the last decade in the context of target tracking, with regard to either a single target or multiple targets in the presence of false or missing data. The [...] Read more.

We review some advances of the particle filtering (PF) algorithm that have been achieved in the last decade in the context of target tracking, with regard to either a single target or multiple targets in the presence of false or missing data. The first part of our review is on remarkable achievements that have been made for the single-target PF from several aspects including importance proposal, computing efficiency, particle degeneracy/impoverishment and constrained/multi-modal systems. The second part of our review is on analyzing the intractable challenges raised within the general multitarget (multi-sensor) tracking due to random target birth and termination, false alarm, misdetection, measurement-to-track (M2T) uncertainty and track uncertainty. The mainstream multitarget PF approaches consist of two main classes, one based on M2T association approaches and the other not such as the finite set statistics-based PF. In either case, significant challenges remain due to unknown tracking scenarios and integrated tracking management. Full article

(This article belongs to the Section Intelligent Sensors)

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26 pages, 6845 KiB

Open AccessReview

Surface Acoustic Wave (SAW) for Chemical Sensing Applications of Recognition Layers

by Adnan Mujahid^1,2

and Franz L. Dickert^1,*

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

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

Sensors 2017, 17(12), 2716; https://doi.org/10.3390/s17122716 - 24 Nov 2017

Cited by 152 | Viewed by 19016

Abstract

Surface acoustic wave (SAW) resonators represent some of the most prominent acoustic devices for chemical sensing applications. As their frequency ranges from several hundred MHz to GHz, therefore they can record remarkably diminutive frequency shifts resulting from exceptionally small mass loadings. Their miniaturized [...] Read more.

Surface acoustic wave (SAW) resonators represent some of the most prominent acoustic devices for chemical sensing applications. As their frequency ranges from several hundred MHz to GHz, therefore they can record remarkably diminutive frequency shifts resulting from exceptionally small mass loadings. Their miniaturized design, high thermal stability and possibility of wireless integration make these devices highly competitive. Owing to these special characteristics, they are widely accepted as smart transducers that can be combined with a variety of recognition layers based on host-guest interactions, metal oxide coatings, carbon nanotubes, graphene sheets, functional polymers and biological receptors. As a result of this, there is a broad spectrum of SAW sensors, i.e., having sensing applications ranging from small gas molecules to large bio-analytes or even whole cell structures. This review shall cover from the fundamentals to modern design developments in SAW devices with respect to interfacial receptor coatings for exemplary sensor applications. The related problems and their possible solutions shall also be covered, with a focus on emerging trends and future opportunities for making SAW as established sensing technology. Full article

(This article belongs to the Special Issue Surface Acoustic Wave and Bulk Acoustic Wave Sensors)

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19 pages, 5962 KiB

Open AccessReview

Surface Plasmon Resonance Sensors on Raman and Fluorescence Spectroscopy

by Jiangcai Wang^1,2,†, Weihua Lin^1,2,†, En Cao^1,2,†, Xuefeng Xu^1,†, Wenjie Liang² and Xiaofang Zhang^1,*

¹ Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China

² Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing 100190, China

^† These authors contributed equally.

Sensors 2017, 17(12), 2719; https://doi.org/10.3390/s17122719 - 24 Nov 2017

Cited by 76 | Viewed by 11074

Abstract

The performance of chemical reactions has been enhanced immensely with surface plasmon resonance (SPR)-based sensors. In this review, the principle and application of SPR sensors are introduced and summarized thoroughly. We introduce the mechanism of the SPR sensors and present a thorough summary [...] Read more.

The performance of chemical reactions has been enhanced immensely with surface plasmon resonance (SPR)-based sensors. In this review, the principle and application of SPR sensors are introduced and summarized thoroughly. We introduce the mechanism of the SPR sensors and present a thorough summary about the optical design, including the substrate and excitation modes of the surface plasmons. Additionally, the applications based on SPR sensors are described by the Raman and fluorescence spectroscopy in plasmon-driven surface catalytic reactions and the measurement of refractive index sensing, especially. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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20 pages, 4849 KiB

Open AccessReview

Plasmonic Optical Fiber-Grating Immunosensing: A Review

by Tuan Guo¹

, Álvaro González-Vila²

, Médéric Loyez² and Christophe Caucheteur^2,*

¹ Institute of Photonics Technology, Jinan University, Guangzhou 510632, China

² Electromagnetism and Telecommunication Department, University of Mons, Boulevard Dolez 31, 7000 Mons, Belgium

Sensors 2017, 17(12), 2732; https://doi.org/10.3390/s17122732 - 26 Nov 2017

Cited by 112 | Viewed by 11077

Abstract

Plasmonic immunosensors are usually made of a noble metal (in the form of a film or nanoparticles) on which bioreceptors are grafted to sense analytes based on the antibody/antigen or other affinity mechanism. Optical fiber configurations are a miniaturized counterpart to the bulky [...] Read more.

Plasmonic immunosensors are usually made of a noble metal (in the form of a film or nanoparticles) on which bioreceptors are grafted to sense analytes based on the antibody/antigen or other affinity mechanism. Optical fiber configurations are a miniaturized counterpart to the bulky Kretschmann prism and allow easy light injection and remote operation. To excite a surface plasmon (SP), the core-guided light is locally outcoupled. Unclad optical fibers were the first configurations reported to this end. Among the different architectures able to bring light in contact with the surrounding medium, a great quantity of research is today being conducted on metal-coated fiber gratings photo-imprinted in the fiber core, as they provide modal features that enable SP generation at any wavelength, especially in the telecommunication window. They are perfectly suited for use with cost-effective high-resolution interrogators, allowing both a high sensitivity and a low limit of detection to be reached in immunosensing. This paper will review recent progress made in this field with different kinds of gratings: uniform, tilted and eccentric short-period gratings as well as long-period fiber gratings. Practical cases will be reported, showing that such sensors can be used in very small volumes of analytes and even possibly applied to in vivo diagnosis. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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30 pages, 44522 KiB

Open AccessReview

The Morphologies of the Semiconductor Oxides and Their Gas-Sensing Properties

by Tingting Lin^1,2

, Xin Lv^1,2

, Shuang Li^1,2 and Qingji Wang^1,2,*

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

² Key Laboratory of Geophysics Exploration Equipment, Ministry of Education of China, Changchun 130061, China

Sensors 2017, 17(12), 2779; https://doi.org/10.3390/s17122779 - 30 Nov 2017

Cited by 87 | Viewed by 10021

Abstract

Semiconductor oxide chemoresistive gas sensors are widely used for detecting deleterious gases due to low cost, simple preparation, rapid response and high sensitivity. The performance of gas sensor is greatly affected by the morphology of the semiconductor oxide. There are many semiconductor oxide [...] Read more.

Semiconductor oxide chemoresistive gas sensors are widely used for detecting deleterious gases due to low cost, simple preparation, rapid response and high sensitivity. The performance of gas sensor is greatly affected by the morphology of the semiconductor oxide. There are many semiconductor oxide morphologies, including zero-dimensional, one-dimensional, two-dimensional and three-dimensional ones. The semiconductor oxides with different morphologies significantly enhance the gas-sensing performance. Among the various morphologies, hollow nanostructures and core-shell nanostructures are always the focus of research in the field of gas sensors due to their distinctive structural characteristics and superior performance. Herein the morphologies of semiconductor oxides and their gas-sensing properties are reviewed. This review also proposes a potential strategy for the enhancement of gas-sensing performance in the future. Full article

(This article belongs to the Special Issue Gas Sensors based on Semiconducting Metal Oxides)

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16 pages, 5566 KiB

Open AccessReview

Superconducting Quantum Interferometers for Nondestructive Evaluation

by M. I. Faley^1,*

, E. A. Kostyurina^2,3, K. V. Kalashnikov^2,3, Yu. V. Maslennikov³, V. P. Koshelets³ and R. E. Dunin-Borkowski¹

¹ Peter Grünberg Institute, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany

² Moscow Institute of Physics and Technology, Moscow 141700, Russia

³ Kotel’nikov Institute of Radio Engineering & Electronics RAS, Moscow 125009, Russia

Sensors 2017, 17(12), 2798; https://doi.org/10.3390/s17122798 - 6 Dec 2017

Cited by 20 | Viewed by 8776

Abstract

We review stationary and mobile systems that are used for the nondestructive evaluation of room temperature objects and are based on superconducting quantum interference devices (SQUIDs). The systems are optimized for samples whose dimensions are between 10 micrometers and several meters. Stray magnetic [...] Read more.

We review stationary and mobile systems that are used for the nondestructive evaluation of room temperature objects and are based on superconducting quantum interference devices (SQUIDs). The systems are optimized for samples whose dimensions are between 10 micrometers and several meters. Stray magnetic fields from small samples (10 µm–10 cm) are studied using a SQUID microscope equipped with a magnetic flux antenna, which is fed through the walls of liquid nitrogen cryostat and a hole in the SQUID’s pick-up loop and returned sidewards from the SQUID back to the sample. The SQUID microscope does not disturb the magnetization of the sample during image recording due to the decoupling of the magnetic flux antenna from the modulation and feedback coil. For larger samples, we use a hand-held mobile liquid nitrogen minicryostat with a first order planar gradiometric SQUID sensor. Low-T_c DC SQUID systems that are designed for NDE measurements of bio-objects are able to operate with sufficient resolution in a magnetically unshielded environment. High-T_c DC SQUID magnetometers that are operated in a magnetic shield demonstrate a magnetic field resolution of ~4 fT/√Hz at 77 K. This sensitivity is improved to ~2 fT/√Hz at 77 K by using a soft magnetic flux antenna. Full article

(This article belongs to the Special Issue Intelligent Sensing Technologies for Nondestructive Evaluation)

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41 pages, 8778 KiB

Open AccessReview

Quartz Crystal Microbalance Electronic Interfacing Systems: A Review

by Abdulrahman Alassi^1,*

, Mohieddine Benammar^1,*

and Dan Brett²

¹ Department of Electrical Engineering, Qatar University, Doha 2713, Qatar

² Department of Chemical Engineering, University College London, London WC1E 6BT, UK

Sensors 2017, 17(12), 2799; https://doi.org/10.3390/s17122799 - 5 Dec 2017

Cited by 162 | Viewed by 22528

Abstract

Quartz Crystal Microbalance (QCM) sensors are actively being implemented in various fields due to their compatibility with different operating conditions in gaseous/liquid mediums for a wide range of measurements. This trend has been matched by the parallel advancement in tailored electronic interfacing systems [...] Read more.

Quartz Crystal Microbalance (QCM) sensors are actively being implemented in various fields due to their compatibility with different operating conditions in gaseous/liquid mediums for a wide range of measurements. This trend has been matched by the parallel advancement in tailored electronic interfacing systems for QCM sensors. That is, selecting the appropriate electronic circuit is vital for accurate sensor measurements. Many techniques were developed over time to cover the expanding measurement requirements (e.g., accommodating highly-damping environments). This paper presents a comprehensive review of the various existing QCM electronic interfacing systems. Namely, impedance-based analysis, oscillators (conventional and lock-in based techniques), exponential decay methods and the emerging phase-mass based characterization. The aforementioned methods are discussed in detail and qualitatively compared in terms of their performance for various applications. In addition, some theoretical improvements and recommendations are introduced for adequate systems implementation. Finally, specific design considerations of high-temperature microbalance systems (e.g., GaPO₄ crystals (GCM) and Langasite crystals (LCM)) are introduced, while assessing their overall system performance, stability and quality compared to conventional low-temperature applications. Full article

(This article belongs to the Section Chemical Sensors)

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15 pages, 2087 KiB

Open AccessReview

Recent Advances in Fluorescence Lifetime Analytical Microsystems: Contact Optics and CMOS Time-Resolved Electronics

by Liping Wei

, Wenrong Yan and Derek Ho^*

Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong 999077, China

Sensors 2017, 17(12), 2800; https://doi.org/10.3390/s17122800 - 4 Dec 2017

Cited by 28 | Viewed by 8800

Abstract

Fluorescence spectroscopy has become a prominent research tool with wide applications in medical diagnostics and bio-imaging. However, the realization of combined high-performance, portable, and low-cost spectroscopic sensors still remains a challenge, which has limited the technique to the laboratories. A fluorescence lifetime measurement [...] Read more.

Fluorescence spectroscopy has become a prominent research tool with wide applications in medical diagnostics and bio-imaging. However, the realization of combined high-performance, portable, and low-cost spectroscopic sensors still remains a challenge, which has limited the technique to the laboratories. A fluorescence lifetime measurement seeks to obtain the characteristic lifetime from the fluorescence decay profile. Time-correlated single photon counting (TCSPC) and time-gated techniques are two key variations of time-resolved measurements. However, commercial time-resolved analysis systems typically contain complex optics and discrete electronic components, which lead to bulkiness and a high cost. These two limitations can be significantly mitigated using contact sensing and complementary metal-oxide-semiconductor (CMOS) implementation. Contact sensing simplifies the optics, whereas CMOS technology enables on-chip, arrayed detection and signal processing, significantly reducing size and power consumption. This paper examines recent advances in contact sensing and CMOS time-resolved circuits for the realization of fully integrated fluorescence lifetime measurement microsystems. The high level of performance from recently reported prototypes suggests that the CMOS-based contact sensing microsystems are emerging as sound technologies for application-specific, low-cost, and portable time-resolved diagnostic devices. Full article

(This article belongs to the Special Issue Novel Sensors for Bioimaging)

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23 pages, 3599 KiB

Open AccessReview

Construction and Potential Applications of Biosensors for Proteins in Clinical Laboratory Diagnosis

by Xuan Liu¹ and Hui Jiang^2,*

¹ Department of Clinical Laboratory, The Second Affiliated Hospital of Southeast University, Nanjing 210003, China

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

Sensors 2017, 17(12), 2805; https://doi.org/10.3390/s17122805 - 4 Dec 2017

Cited by 18 | Viewed by 5784

Abstract

Biosensors for proteins have shown attractive advantages compared to traditional techniques in clinical laboratory diagnosis. In virtue of modern fabrication modes and detection techniques, various immunosensing platforms have been reported on basis of the specific recognition between antigen-antibody pairs. In addition to profit [...] Read more.

Biosensors for proteins have shown attractive advantages compared to traditional techniques in clinical laboratory diagnosis. In virtue of modern fabrication modes and detection techniques, various immunosensing platforms have been reported on basis of the specific recognition between antigen-antibody pairs. In addition to profit from the development of nanotechnology and molecular biology, diverse fabrication and signal amplification strategies have been designed for detection of protein antigens, which has led to great achievements in fast quantitative and simultaneous testing with extremely high sensitivity and specificity. Besides antigens, determination of antibodies also possesses great significance for clinical laboratory diagnosis. In this review, we will categorize recent immunosensors for proteins by different detection techniques. The basic conception of detection techniques, sensing mechanisms, and the relevant signal amplification strategies are introduced. Since antibodies and antigens have an equal position to each other in immunosensing, all biosensing strategies for antigens can be extended to antibodies under appropriate optimizations. Biosensors for antibodies are summarized, focusing on potential applications in clinical laboratory diagnosis, such as a series of biomarkers for infectious diseases and autoimmune diseases, and an evaluation of vaccine immunity. The excellent performances of these biosensors provide a prospective space for future antibody-detection-based disease serodiagnosis. Full article

(This article belongs to the Section Biosensors)

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14 pages, 1425 KiB

Open AccessReview

Phase-Sensitive Surface Plasmon Resonance Sensors: Recent Progress and Future Prospects

by Shijie Deng, Peng Wang^* and Xinglong Yu

State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084, China

Sensors 2017, 17(12), 2819; https://doi.org/10.3390/s17122819 - 5 Dec 2017

Cited by 82 | Viewed by 8982

Abstract

Surface plasmon resonance (SPR) is an optical sensing technique that is capable of performing real-time, label-free and high-sensitivity monitoring of molecular interactions. SPR biosensors can be divided according to their operating principles into angle-, wavelength-, intensity- and phase-interrogated devices. With their complex optical [...] Read more.

Surface plasmon resonance (SPR) is an optical sensing technique that is capable of performing real-time, label-free and high-sensitivity monitoring of molecular interactions. SPR biosensors can be divided according to their operating principles into angle-, wavelength-, intensity- and phase-interrogated devices. With their complex optical configurations, phase-interrogated SPR sensors generally provide higher sensitivity and throughput, and have thus recently emerged as prominent biosensing devices. To date, several methods have been developed for SPR phase interrogation, including heterodyne detection, polarimetry, shear interferometry, spatial phase modulation interferometry and temporal phase modulation interferometry. This paper summarizes the fundamentals of phase-sensitive SPR sensing, reviews the available methods for phase interrogation of these sensors, and discusses the future prospects for and trends in the development of this technology. Full article

(This article belongs to the Special Issue Surface Plasmon Resonance Sensing)

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24 pages, 9882 KiB

Open AccessReview

Luminescence-Based Optical Sensors Fabricated by Means of the Layer-by-Layer Nano-Assembly Technique

by Nerea De Acha^1,*, Cesar Elosua^1,2

, Ignacio Matias^1,2 and Francisco Javier Arregui^1,2

¹ Department of Electric and Electronic Engineering, Public University of Navarra, E-31006 Pamplona, Spain

² Institute of Smart Cities (ISC), Public University of Navarra, E-31006 Pamplona, Spain

Sensors 2017, 17(12), 2826; https://doi.org/10.3390/s17122826 - 6 Dec 2017

Cited by 23 | Viewed by 7505

Abstract

Luminescence-based sensing applications range from agriculture to biology, including medicine and environmental care, which indicates the importance of this technique as a detection tool. Luminescent optical sensors are required to be highly stable, sensitive, and selective, three crucial features that can be achieved [...] Read more.

Luminescence-based sensing applications range from agriculture to biology, including medicine and environmental care, which indicates the importance of this technique as a detection tool. Luminescent optical sensors are required to be highly stable, sensitive, and selective, three crucial features that can be achieved by fabricating them by means of the layer-by-layer nano-assembly technique. This method permits us to tailor the sensors′ properties at the nanometer scale, avoiding luminophore aggregation and, hence, self-quenching, promoting the diffusion of the target analytes, and building a barrier against the undesired molecules. These characteristics give rise to the fabrication of custom-made sensors for each particular application. Full article

(This article belongs to the Special Issue Fluorescent Probes and Sensors)

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26 pages, 2032 KiB

Open AccessReview

Three-Dimensional Shape Measurements of Specular Objects Using Phase-Measuring Deflectometry

by Zonghua Zhang^1,2,*

, Yuemin Wang¹, Shujun Huang¹, Yue Liu², Caixia Chang¹, Feng Gao²

and Xiangqian Jiang²

¹ School of Mechanical Engineering, Hebei University of Technology, Tianjin 300130, China

² Centre for Precision Technologies, University of Huddersfield, Huddersfield, HD1 3DH, UK

Sensors 2017, 17(12), 2835; https://doi.org/10.3390/s17122835 - 7 Dec 2017

Cited by 88 | Viewed by 11108

Abstract

The fast development in the fields of integrated circuits, photovoltaics, the automobile industry, advanced manufacturing, and astronomy have led to the importance and necessity of quickly and accurately obtaining three-dimensional (3D) shape data of specular surfaces for quality control and function evaluation. Owing [...] Read more.

The fast development in the fields of integrated circuits, photovoltaics, the automobile industry, advanced manufacturing, and astronomy have led to the importance and necessity of quickly and accurately obtaining three-dimensional (3D) shape data of specular surfaces for quality control and function evaluation. Owing to the advantages of a large dynamic range, non-contact operation, full-field and fast acquisition, high accuracy, and automatic data processing, phase-measuring deflectometry (PMD, also called fringe reflection profilometry) has been widely studied and applied in many fields. Phase information coded in the reflected fringe patterns relates to the local slope and height of the measured specular objects. The 3D shape is obtained by integrating the local gradient data or directly calculating the depth data from the phase information. We present a review of the relevant techniques regarding classical PMD. The improved PMD technique is then used to measure specular objects having discontinuous and/or isolated surfaces. Some influential factors on the measured results are presented. The challenges and future research directions are discussed to further advance PMD techniques. Finally, the application fields of PMD are briefly introduced. Full article

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

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20 pages, 3525 KiB

Open AccessReview

Biomimetic Sensors for the Senses: Towards Better Understanding of Taste and Odor Sensation

by Chunsheng Wu^1,5, Ya-Wen Du², Liquan Huang^2,3, Yaron Ben-Shoshan Galeczki⁴, Ayana Dagan-Wiener⁴, Michael Naim⁴, Masha Y. Niv^4,* and Ping Wang^5,*

¹ Institute of Medical Engineering, School of Basic Medical Science, Health Science Center, Xi’an Jiaotong University, Xi’an 710061, China

² College of Life Sciences, Zhejiang University, Hangzhou 310013, China

³ Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA

⁴ The Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel

⁵ Biosensor National Special Laboratory, Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China

Sensors 2017, 17(12), 2881; https://doi.org/10.3390/s17122881 - 11 Dec 2017

Cited by 19 | Viewed by 8319

Abstract

Taste and smell are very important chemical senses that provide indispensable information on food quality, potential mates and potential danger. In recent decades, much progress has been achieved regarding the underlying molecular and cellular mechanisms of taste and odor senses. Recently, biosensors have [...] Read more.

Taste and smell are very important chemical senses that provide indispensable information on food quality, potential mates and potential danger. In recent decades, much progress has been achieved regarding the underlying molecular and cellular mechanisms of taste and odor senses. Recently, biosensors have been developed for detecting odorants and tastants as well as for studying ligand-receptor interactions. This review summarizes the currently available biosensing approaches, which can be classified into two main categories: in vitro and in vivo approaches. The former is based on utilizing biological components such as taste and olfactory tissues, cells and receptors, as sensitive elements. The latter is dependent on signals recorded from animals’ signaling pathways using implanted microelectrodes into living animals. Advantages and disadvantages of these two approaches, as well as differences in terms of sensing principles and applications are highlighted. The main current challenges, future trends and prospects of research in biomimetic taste and odor sensors are discussed. Full article

(This article belongs to the Special Issue Electronic Tongues and Electronic Noses)

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34 pages, 26186 KiB

Open AccessReview

Performance Evaluation of Bluetooth Low Energy: A Systematic Review

by Jacopo Tosi^1,2,*

, Fabrizio Taffoni^1,2, Marco Santacatterina³, Roberto Sannino³ and Domenico Formica¹

¹ NeXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, School of Medicine, Università Campus Bio-Medico di Roma, 00128 Rome, Italy

² Unit of Biomedical Robotics and Biomicrosystems, School of Engineering, Università Campus Bio-Medico di Roma, 00128 Rome, Italy

³ STMicroelectronics, 20864 Agrate Brianza (MB), Italy

Sensors 2017, 17(12), 2898; https://doi.org/10.3390/s17122898 - 13 Dec 2017

Cited by 165 | Viewed by 25104

Abstract

Small, compact and embedded sensors are a pervasive technology in everyday life for a wide number of applications (e.g., wearable devices, domotics, e-health systems, etc.). In this context, wireless transmission plays a key role, and among available solutions, Bluetooth Low Energy (BLE) is [...] Read more.

Small, compact and embedded sensors are a pervasive technology in everyday life for a wide number of applications (e.g., wearable devices, domotics, e-health systems, etc.). In this context, wireless transmission plays a key role, and among available solutions, Bluetooth Low Energy (BLE) is gaining more and more popularity. BLE merges together good performance, low-energy consumption and widespread diffusion. The aim of this work is to review the main methodologies adopted to investigate BLE performance. The first part of this review is an in-depth description of the protocol, highlighting the main characteristics and implementation details. The second part reviews the state of the art on BLE characteristics and performance. In particular, we analyze throughput, maximum number of connectable sensors, power consumption, latency and maximum reachable range, with the aim to identify what are the current limits of BLE technology. The main results can be resumed as follows: throughput may theoretically reach the limit of ~230 kbps, but actual applications analyzed in this review show throughputs limited to ~100 kbps; the maximum reachable range is strictly dependent on the radio power, and it goes up to a few tens of meters; the maximum number of nodes in the network depends on connection parameters, on the network architecture and specific device characteristics, but it is usually lower than 10; power consumption and latency are largely modeled and analyzed and are strictly dependent on a huge number of parameters. Most of these characteristics are based on analytical models, but there is a need for rigorous experimental evaluations to understand the actual limits. Full article

(This article belongs to the Section Sensor Networks)

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33 pages, 15343 KiB

Open AccessReview

Extreme Environment Sensing Using Femtosecond Laser-Inscribed Fiber Bragg Gratings

by Stephen J. Mihailov^*

, Dan Grobnic, Cyril Hnatovsky, Robert B. Walker, Ping Lu

, David Coulas and Huimin Ding

National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada

Sensors 2017, 17(12), 2909; https://doi.org/10.3390/s17122909 - 14 Dec 2017

Cited by 127 | Viewed by 9730

Abstract

The femtosecond laser-induced fiber Bragg grating is an effective sensor technology that can be deployed in harsh environments. Depending on the optical fiber chosen and the inscription parameters that are used, devices suitable for high temperature, pressure, ionizing radiation and strain sensor applications [...] Read more.

The femtosecond laser-induced fiber Bragg grating is an effective sensor technology that can be deployed in harsh environments. Depending on the optical fiber chosen and the inscription parameters that are used, devices suitable for high temperature, pressure, ionizing radiation and strain sensor applications are possible. Such devices are appropriate for aerospace or energy production applications where there is a need for components, instrumentation and controls that can function in harsh environments. This paper will present a review of some of the more recent developments in this field. Full article

(This article belongs to the Special Issue Fiber Bragg Grating Based Sensors)

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25 pages, 2822 KiB

Open AccessReview

Recent Progress in Biosensors for Environmental Monitoring: A Review

by Celine I. L. Justino^1,2,*

, Armando C. Duarte¹

and Teresa A. P. Rocha-Santos¹

¹ Department of Chemistry & CESAM, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal

² ISEIT/Viseu, Instituto Piaget, Estrada do Alto do Gaio, Galifonge, Lordosa, 3515-776 Viseu, Portugal

Sensors 2017, 17(12), 2918; https://doi.org/10.3390/s17122918 - 15 Dec 2017

Cited by 320 | Viewed by 18260

Abstract

The environmental monitoring has been one of the priorities at the European and global scale due to the close relationship between the environmental pollution and the human health/socioeconomic development. In this field, the biosensors have been widely employed as cost-effective, fast, in situ, [...] Read more.

The environmental monitoring has been one of the priorities at the European and global scale due to the close relationship between the environmental pollution and the human health/socioeconomic development. In this field, the biosensors have been widely employed as cost-effective, fast, in situ, and real-time analytical techniques. The need of portable, rapid, and smart biosensing devices explains the recent development of biosensors with new transduction materials, obtained from nanotechnology, and for multiplexed pollutant detection, involving multidisciplinary experts. This review article provides an update on recent progress in biosensors for the monitoring of air, water, and soil pollutants in real conditions such as pesticides, potentially toxic elements, and small organic molecules including toxins and endocrine disrupting chemicals. Full article

(This article belongs to the Special Issue Environmental Monitoring Biosensors)

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15 pages, 1323 KiB

Open AccessReview

Lab-on-a-Chip Platforms for Detection of Cardiovascular Disease and Cancer Biomarkers

by Jiandong Wu^1,†, Meili Dong^1,2,†, Susy Santos³, Claudio Rigatto⁴, Yong Liu^2,* and Francis Lin^1,*

¹ Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada

² Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230088, China

³ Victoria General Hospital and River Heights/Fort Garry Community Areas, Winnipeg, MB, R3T 2E8, Canada

⁴ Seven Oaks General Hospital, Winnipeg, MB, R2V 3M3, Canada

^† These authors contributed equally.

Sensors 2017, 17(12), 2934; https://doi.org/10.3390/s17122934 - 17 Dec 2017

Cited by 65 | Viewed by 14402

Abstract

Cardiovascular disease (CVD) and cancer are two leading causes of death worldwide. CVD and cancer share risk factors such as obesity and diabetes mellitus and have common diagnostic biomarkers such as interleukin-6 and C-reactive protein. Thus, timely and accurate diagnosis of these two [...] Read more.

Cardiovascular disease (CVD) and cancer are two leading causes of death worldwide. CVD and cancer share risk factors such as obesity and diabetes mellitus and have common diagnostic biomarkers such as interleukin-6 and C-reactive protein. Thus, timely and accurate diagnosis of these two correlated diseases is of high interest to both the research and healthcare communities. Most conventional methods for CVD and cancer biomarker detection such as microwell plate-based immunoassay and polymerase chain reaction often suffer from high costs, low test speeds, and complicated procedures. Recently, lab-on-a-chip (LoC)-based platforms have been increasingly developed for CVD and cancer biomarker sensing and analysis using various molecular and cell-based diagnostic biomarkers. These new platforms not only enable better sample preparation, chemical manipulation and reaction, high-throughput and portability, but also provide attractive features such as label-free detection and improved sensitivity due to the integration of various novel detection techniques. These features effectively improve the diagnostic test speed and simplify the detection procedure. In addition, microfluidic cell assays and organ-on-chip models offer new potential approaches for CVD and cancer diagnosis. Here we provide a mini-review focusing on recent development of LoC-based methods for CVD and cancer diagnostic biomarker measurements, and our perspectives of the challenges, opportunities and future directions. Full article

(This article belongs to the Special Issue Sensors for Health Monitoring and Disease Diagnosis)

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25 pages, 5647 KiB

Open AccessReview

Porous TiO₂-Based Gas Sensors for Cyber Chemical Systems to Provide Security and Medical Diagnosis

by Vardan Galstyan

Sensor Lab, Department of Information Engineering, University of Brescia, Via Valotti 9, 25133 Brescia, Italy

Sensors 2017, 17(12), 2947; https://doi.org/10.3390/s17122947 - 19 Dec 2017

Cited by 67 | Viewed by 10662

Abstract

Gas sensors play an important role in our life, providing control and security of technical processes, environment, transportation and healthcare. Consequently, the development of high performance gas sensor devices is the subject of intense research. TiO₂, with its excellent physical and [...] Read more.

Gas sensors play an important role in our life, providing control and security of technical processes, environment, transportation and healthcare. Consequently, the development of high performance gas sensor devices is the subject of intense research. TiO₂, with its excellent physical and chemical properties, is a very attractive material for the fabrication of chemical sensors. Meanwhile, the emerging technologies are focused on the fabrication of more flexible and smart systems for precise monitoring and diagnosis in real-time. The proposed cyber chemical systems in this paper are based on the integration of cyber elements with the chemical sensor devices. These systems may have a crucial effect on the environmental and industrial safety, control of carriage of dangerous goods and medicine. This review highlights the recent developments on fabrication of porous TiO₂-based chemical gas sensors for their application in cyber chemical system showing the convenience and feasibility of such a model to provide the security and to perform the diagnostics. The most of reports have demonstrated that the fabrication of doped, mixed and composite structures based on porous TiO₂ may drastically improve its sensing performance. In addition, each component has its unique effect on the sensing properties of material. Full article

(This article belongs to the Collection Gas Sensors)

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21 pages, 1536 KiB

Open AccessReview

Achievements and Prospects in Electrochemical-Based Biosensing Platforms for Aflatoxin M₁ Detection in Milk and Dairy Products

by Ana-Maria Gurban^1,*

, Petru Epure², Florin Oancea¹

and Mihaela Doni^1,*

¹ Biotechnology Department, National Institute for Research & Development in Chemistry and Petrochemistry—ICECHIM, 202 Spl. Independentei, Sector 6, 060021 Bucharest, Romania

² EPI-SISTEM SRL, Bvd Brasovului 145, Sacele, 505600 Brasov, Romania

Sensors 2017, 17(12), 2951; https://doi.org/10.3390/s17122951 - 19 Dec 2017

Cited by 29 | Viewed by 8183

Abstract

Aflatoxins, which are mainly produced by Aspergillus flavus and parasiticus growing on plants and products stored under inappropriate conditions, represent the most studied group of mycotoxins. Contamination of human and animal milk with aflatoxin M₁, the hydroxylated metabolite of aflatoxin B [...] Read more.

Aflatoxins, which are mainly produced by Aspergillus flavus and parasiticus growing on plants and products stored under inappropriate conditions, represent the most studied group of mycotoxins. Contamination of human and animal milk with aflatoxin M₁, the hydroxylated metabolite of aflatoxin B₁, is an important health risk factor due to its carcinogenicity and mutagenicity. Due to the low concentration of this aflatoxin in milk and milk products, the analytical methods used for its quantification have to be highly sensitive, specific and simple. This paper presents an overview of the analytical methods, especially of the electrochemical immunosensors and aptasensors, used for determination of aflatoxin M₁. Full article

(This article belongs to the Special Issue Protein-Based Biosensors)

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27 pages, 2456 KiB

Open AccessReview

Sensors and Biosensors for C-Reactive Protein, Temperature and pH, and Their Applications for Monitoring Wound Healing: A Review

by Pietro Salvo^1,2,*

, Valentina Dini³, Arno Kirchhain², Agata Janowska³, Teresa Oranges³, Andrea Chiricozzi³

, Tommaso Lomonaco²

, Fabio Di Francesco² and Marco Romanelli³

¹ Institute of Clinical Physiology, National Council of Research (IFC-CNR), Via Moruzzi 1, 56124 Pisa, Italy

² Department of Chemistry and Industrial Chemistry, University of Pisa, Via Moruzzi 13, 56124 Pisa, Italy

³ Department of Dermatology, University of Pisa, Via Roma 67, 56126 Pisa, Italy

Sensors 2017, 17(12), 2952; https://doi.org/10.3390/s17122952 - 19 Dec 2017

Cited by 106 | Viewed by 15218

Abstract

Wound assessment is usually performed in hospitals or specialized labs. However, since patients spend most of their time at home, a remote real time wound monitoring would help providing a better care and improving the healing rate. This review describes the advances in [...] Read more.

Wound assessment is usually performed in hospitals or specialized labs. However, since patients spend most of their time at home, a remote real time wound monitoring would help providing a better care and improving the healing rate. This review describes the advances in sensors and biosensors for monitoring the concentration of C-reactive protein (CRP), temperature and pH in wounds. These three parameters can be used as qualitative biomarkers to assess the wound status and the effectiveness of therapy. CRP biosensors can be classified in: (a) field effect transistors, (b) optical immunosensors based on surface plasmon resonance, total internal reflection, fluorescence and chemiluminescence, (c) electrochemical sensors based on potentiometry, amperometry, and electrochemical impedance, and (d) piezoresistive sensors, such as quartz crystal microbalances and microcantilevers. The last section reports the most recent developments for wearable non-invasive temperature and pH sensors suitable for wound monitoring. Full article

(This article belongs to the Special Issue Biomedical Sensors and Systems 2017)

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32 pages, 7074 KiB

Open AccessConcept Paper

E2mC: Improving Emergency Management Service Practice through Social Media and Crowdsourcing Analysis in Near Real Time

by Clemens Havas^1,*

, Bernd Resch^1,2

, Chiara Francalanci³, Barbara Pernici³, Gabriele Scalia³

, Jose Luis Fernandez-Marquez⁴, Tim Van Achte⁵

, Gunter Zeug⁶, Maria Rosa (Rosy) Mondardini⁴, Domenico Grandoni⁷, Birgit Kirsch⁸, Milan Kalas⁹, Valerio Lorini⁹ and Stefan Rüping⁸

¹ Department of Geoinformatics–Z_GIS, University of Salzburg, Schillerstrasse 30, 5020 Salzburg, Austria

² Center for Geographic Analysis, Harvard University, Cambridge, MA 02138, USA

³ Department of Electronics, Information and Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20131 Milano, Italy

⁴ Citizen Cyberlab, Centre Universitaire d’Informatique (CUI), University of Geneva, route de Drize CH-1227 Carouge, Switzerland

⁵ PM Risk Crisis Change, K. M. Hendrikaplein 57, 9000 Ghent, Belgium

⁶ Terranea, Bahnhofstr. 120, 82269 Geltendorf, Germany

⁷ e-GEOS S.p.A, Via Tiburtina 965, 00156, Rome, Italy

⁸ Fraunhofer Institute for Intelligent Analysis and Information Systems IAIS, Schloss Birlinghoven, 53757 Sankt Augustin, Germany

⁹ KAJO s. r. o., Sladkovicova 228/8, 01401 Bytca, Slovakia

Sensors 2017, 17(12), 2766; https://doi.org/10.3390/s17122766 - 29 Nov 2017

Cited by 62 | Viewed by 11141

Abstract

In the first hours of a disaster, up-to-date information about the area of interest is crucial for effective disaster management. However, due to the delay induced by collecting and analysing satellite imagery, disaster management systems like the Copernicus Emergency Management Service (EMS) are [...] Read more.

In the first hours of a disaster, up-to-date information about the area of interest is crucial for effective disaster management. However, due to the delay induced by collecting and analysing satellite imagery, disaster management systems like the Copernicus Emergency Management Service (EMS) are currently not able to provide information products until up to 48–72 h after a disaster event has occurred. While satellite imagery is still a valuable source for disaster management, information products can be improved through complementing them with user-generated data like social media posts or crowdsourced data. The advantage of these new kinds of data is that they are continuously produced in a timely fashion because users actively participate throughout an event and share related information. The research project Evolution of Emergency Copernicus services (E2mC) aims to integrate these novel data into a new EMS service component called Witness, which is presented in this paper. Like this, the timeliness and accuracy of geospatial information products provided to civil protection authorities can be improved through leveraging user-generated data. This paper sketches the developed system architecture, describes applicable scenarios and presents several preliminary case studies, providing evidence that the scientific and operational goals have been achieved. Full article

(This article belongs to the Special Issue Earth Observation and In-Situ Sensing for Risk Assessment from Natural Threats)

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