Journal of Sensors The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Ultrasensitive NO2 Gas Sensor Based on Epitaxial Graphene Thu, 29 Jan 2015 15:29:24 +0000 We report about technology of fabrication and optimization of a gas sensor based on epitaxial graphene. Optimized graphene/metal contact configuration exhibited low contact resistance. Complementary annealing of graphene sensor after each gas exposure led to significant improvement in the sensing performance. The response of the annealed sensor to the nitrogen dioxide (NO2) was tenfold higher than that of an as-fabricated graphene sensor. NO2 concentration as low as 0.2 parts per billion (ppb) was easily detectable. Devices have high signal-to-noise ratio. The detection limit of the graphene sensor was estimated to be 0.6 ppt (parts per trillion). The present technology with additional annealing improves the performance of the graphene based sensor and makes it suitable for the environmental nitrogen dioxide gas monitoring. S. Novikov, N. Lebedeva, and A. Satrapinski Copyright © 2015 S. Novikov et al. All rights reserved. Self-Referenced Plasmon Waveguide Resonance Sensor Using Different Waveguide Modes Wed, 28 Jan 2015 07:11:55 +0000 We report a plasmon waveguide resonance (PWR) sensing structure supporting two waveguide modes for self-referenced measurement. We show theoretically the dual mode PWR sensing structure owns unique opportunities for self-referenced measurement, and the accuracy and cross sensitivity can be optimized by simply varying the gold film thickness or dielectric layer thickness or dielectric film refractive index. This structure may provide an approach owning good compatibility with the surface plasmon resonance and PWR biosensors for self-referenced biosensing. Pengfei Zhang, Le Liu, Yonghong He, Yanhong Ji, and Hui Ma Copyright © 2015 Pengfei Zhang et al. All rights reserved. Resolution Enhancement Method Used for Force Sensing Resistor Array Tue, 27 Jan 2015 12:01:16 +0000 Tactile sensors are one of the major devices that enable robotic systems to interact with the surrounding environment. This research aims to propose a mathematical model to describe the behavior of a tactile sensor based on experimental and statistical analyses and moreover to develop a versatile algorithm that can be applied to different tactile sensor arrays to enhance the limited resolution. With the proposed algorithm, the resolution can be increased up to twenty times if multiple measurements are available. To verify if the proposed algorithm can be used for tactile sensor arrays that are used in robotic system, a force sensing array (FSR) is adopted. The acquired two-dimensional measurements were processed by a resolution enhancement method (REM) to enhance the resolution, which can be used to improve the resolution for single image or multiple measurements. As a result, the resolution of the sensor is increased and it can be used as synthetic skin to identify accurate shapes of objects and applied forces. Karen Flores De Jesus, Marvin H. Cheng, Lei Jiang, and Ezzat G. Bakhoum Copyright © 2015 Karen Flores De Jesus et al. All rights reserved. Rate Allocation for Wireless Multimedia Sensor Networks Using Pricing Mechanism Thu, 22 Jan 2015 10:43:46 +0000 A bandwidth allocation algorithm for wireless multimedia sensor networks is proposed in this paper. On the premise of Initial allocation algorithm based on distortion and congestion model to provide an efficient system performance, the allocation algorithm based on pricing mechanism we proposed balances the real-time requirement of different users by adjusting the bandwidth price in each network and each slot. Simulation results show that the proposed algorithm balances the bandwidth ratio of different users according to the video complexity, and it can provide a good system performance guaranteeing the fairness among the users. Zhang Jian Ming, Wang YI, Xie Ze Ming, Tang Shi Yi, and Ou Hao Yuan Copyright © 2015 Zhang Jian Ming et al. All rights reserved. Fiber-Optic Temperature and Pressure Sensors Applied to Radiofrequency Thermal Ablation in Liver Phantom: Methodology and Experimental Measurements Tue, 20 Jan 2015 06:22:38 +0000 Radiofrequency thermal ablation (RFA) is a procedure aimed at interventional cancer care and is applied to the treatment of small- and midsize tumors in lung, kidney, liver, and other tissues. RFA generates a selective high-temperature field in the tissue; temperature values and their persistency are directly related to the mortality rate of tumor cells. Temperature measurement in up to 3–5 points, using electrical thermocouples, belongs to the present clinical practice of RFA and is the foundation of a physical model of the ablation process. Fiber-optic sensors allow extending the detection of biophysical parameters to a vast plurality of sensing points, using miniature and noninvasive technologies that do not alter the RFA pattern. This work addresses the methodology for optical measurement of temperature distribution and pressure using four different fiber-optic technologies: fiber Bragg gratings (FBGs), linearly chirped FBGs (LCFBGs), Rayleigh scattering-based distributed temperature system (DTS), and extrinsic Fabry-Perot interferometry (EFPI). For each instrument, methodology for ex vivo sensing, as well as experimental results, is reported, leading to the application of fiber-optic technologies in vivo. The possibility of using a fiber-optic sensor network, in conjunction with a suitable ablation device, can enable smart ablation procedure whereas ablation parameters are dynamically changed. Daniele Tosi, Edoardo Gino Macchi, and Alfredo Cigada Copyright © 2015 Daniele Tosi et al. All rights reserved. ETARP: An Energy Efficient Trust-Aware Routing Protocol for Wireless Sensor Networks Sun, 18 Jan 2015 09:11:36 +0000 This paper presents a new routing protocol called Secure and Energy Aware Routing Protocol (ETARP) designed for energy efficiency and security for wireless sensor networks (WSNs). ETARP attempts to deal with WSN applications operating in extreme environments such as the battlefield. The key part of the routing protocol is route selection based on utility theory. The concept of utility is a novel approach to simultaneously factor energy efficiency and trustworthiness of routes in the routing protocol. ETARP discovers and selects routes on the basis of maximum utility with incurring additional cost in overhead compared to the common AODV (Ad Hoc On Demand Distance Vector) routing protocol. Simulation results show that, in comparison to previously proposed routing protocols, namely, AODV-EHA and LTB-AODV (Light-Weight Trust-Based Routing Protocol), the proposed ETARP can keep the same security level while achieving more energy efficiency for data packet delivery. Pu Gong, Thomas M. Chen, and Quan Xu Copyright © 2015 Pu Gong et al. All rights reserved. A Feasibility Study of a Noncontact Torque Sensor with Multiple Hall Sensors Tue, 13 Jan 2015 14:17:48 +0000 The feasibility of a noncontact sensor is investigated. This type of sensor can potentially be used for torque measurement in a speed-variable power transmission system. Torque can be read by examining the phase difference between two induction signals from respective magnetic sensors that detect the magnetic field intensity of permanent magnets mounted on the surface of a shaft in rotation. A real-time measuring algorithm that includes filtering and calibration is adopted to measure the torque magnitude. It is shown that this new torque sensor can perform well under rotation speeds ranging from 300 rpm to 500 rpm. As an interim report rather than a complete development, this work demonstrates the feasibility of noncontact torque measurement by monitoring a magnetic field. The result shows an error of less than 2% within the full test range, which is a sufficient competitive performance for commercial sensors. The price is very low compared to competitors in the marketplace, and the device does not require special handling of the shaft of the surface. Kyungshik Lee and Chongdu Cho Copyright © 2015 Kyungshik Lee and Chongdu Cho. All rights reserved. Defect Automatic Identification of Eddy Current Pulsed Thermography Wed, 31 Dec 2014 06:29:59 +0000 Eddy current pulsed thermography (ECPT) is an effective nondestructive testing and evaluation (NDT&E) technique, and has been applied for a wide range of conductive materials. Manual selected frames have been used for defects detection and quantification. Defects are indicated by high/low temperature in the frames. However, the variation of surface emissivity sometimes introduces illusory temperature inhomogeneity and results in false alarm. To improve the probability of detection, this paper proposes a two-heat balance states-based method which can restrain the influence of the emissivity. In addition, the independent component analysis (ICA) is also applied to automatically identify defect patterns and quantify the defects. An experiment was carried out to validate the proposed methods. Kai Chen, Libing Bai, Yifan Chen, Yuhua Cheng, Shulin Tian, and Peipei Zhu Copyright © 2014 Kai Chen et al. All rights reserved. Autonomic Wireless Sensor Networks: A Systematic Literature Review Mon, 29 Dec 2014 08:33:02 +0000 Autonomic computing (AC) is a promising approach to meet basic requirements in the design of wireless sensor networks (WSNs), and its principles can be applied to efficiently manage nodes operation and optimize network resources. Middleware for WSNs supports the implementation and basic operation of such networks. In this systematic literature review (SLR) we aim to provide an overview of existing WSN middleware systems that address autonomic properties. The main goal is to identify which development approaches of AC are used for designing WSN middleware system, which allow the self-management of WSN. Another goal is finding out which interactions and behavior can be automated in WSN components. We drew the following main conclusions from the SLR results: (i) the selected studies address WSN concerns according to the self- properties of AC, namely, self-configuration, self-healing, self-optimization, and self-protection; (ii) the selected studies use different approaches for managing the dynamic behavior of middleware systems for WSN, such as policy-based reasoning, context-based reasoning, feedback control loops, mobile agents, model transformations, and code generation. Finally, we identified a lack of comprehensive system architecture designs that support the autonomy of sensor networking. Jesús M. T. Portocarrero, Flávia C. Delicato, Paulo F. Pires, Nadia Gámez, Lidia Fuentes, David Ludovino, and Paulo Ferreira Copyright © 2014 Jesús M. T. Portocarrero et al. All rights reserved. Resource Management Technique Based on Lightweight and Compressed Sensing for Mobile Internet of Things Tue, 23 Dec 2014 06:35:55 +0000 In mobile Internet of Tings, based on cross-layer design and resource-aware scheduling, the combination of light weight coding and compressed sensing is used to improve the real-time performance of acquisition of system resource and reliability of resource management in this paper. Compressed sensing scheme based on the adaptive frame format definition of lightweight coding is able to set up the parameters such as sample signal, signal and hops. The nonlinear relationship matrixes between resource information of sensors or system and quality of services are built to manage the global or local network resource scheduling. Experimental results show that the proposed scheme is better than the traditional scheme or resource management based on compressed sensing alone scheme, which can make the system be able to achieve optimal resource allocation. Zhou Jianming, Liu Fan, and Lu Qiuyuan Copyright © 2014 Zhou Jianming et al. All rights reserved. Trace Detection of Pentaerythritol Tetranitrate Using Electrochemical Gas Sensors Mon, 22 Dec 2014 00:10:13 +0000 Selective and sensitive detection of trace amounts of pentaerythritol tetranitrate (PETN) is demonstrated. The screening system is based on a sampling/concentrator front end and electrochemical potentiometric gas sensor as the detector. A single sensor is operated in the dominant hydrocarbon (HC) and nitrogen oxides (NOx) mode by varying the sensor operating condition. The potentiometric sensor with integrated heaters was used to capture the signature of PETN. Quantitative measurements based on hydrocarbon and nitrogen oxide sensor responses indicated that the detector sensitivity scaled proportionally with the mass of the explosives (10 μg down to 200 ng). The ratio of the HC integrated peak area to the NOx integrated peak area is identified as an indicator of selectivity. The HC/NOx ratio is unique for PETN and has a range from 1.7 to 2.7. This detection technique has the potential to become an orthogonal technique to the existing explosive screening technologies for reducing the number of false positives/false negatives in a cost-effective manner. Praveen K. Sekhar, Jie Zhou, Hui Wang, and Eric R. Hamblin Copyright © 2014 Praveen K. Sekhar et al. All rights reserved. Use of Magnetic Fluid in Accelerometers Thu, 18 Dec 2014 09:08:14 +0000 Magnetic fluid accelerometer is designed based on the special physical properties of magnetic fluid. Compared with the conventional acceleration sensors, magnetic fluid accelerometer has stronger shock resistance capability, higher sensitivity, lower energy consumption, and better performance in low frequency response. It satisfies the growing requirements of acceleration sensors. In this paper, the dynamic model and the theory of magnetic fluid accelerometers were presented. The structure characteristics of typical magnetic fluid accelerometers were investigated, and the development trend of magnetic fluid accelerometers in the future was also predicted. Besides, a novel accelerometer with linearity better than 1.5% and sensitivity better than 75 mV/g was proposed. Leping Qian and Decai Li Copyright © 2014 Leping Qian and Decai Li. All rights reserved. A Novel Subnanosecond Monocycle Pulse Generator for UWB Radar Applications Mon, 15 Dec 2014 13:57:35 +0000 A novel ultra-wideband (UWB) monocycle pulse generator with good performance is designed and demonstrated in this paper. It contains a power supply circuit, a pulse drive circuit, a unique pulse forming circuit, and a novel monopolar-to-monocycle pulse transition circuit. The drive circuit employs wideband bipolar junction transistors (BJTs) and linear power amplifier transistor to produce a high amplitude drive pulse, and the pulse forming circuit uses the transition characteristics of step recovery diode (SRD) effectively to produce a negative narrow pulse. At last, the monocycle pulse forming circuit utilizes a novel inductance L short-circuited stub to generate the monocycle pulse directly. Measurement results show that the waveform of the generated monocycle pulses is over 76 V in peak-to-peak amplitude and 3.2 ns in pulse full-width. These characteristics of the monocycle pulse are advantageous for obtaining long detection range and high resolution, when it is applied to ultra-wideband radar applications. Xinfan Xia, Lihua Liu, Shengbo Ye, Hongfei Guan, and Guangyou Fang Copyright © 2014 Xinfan Xia et al. All rights reserved. Frequency Tuning of Work Modes in Z-Axis Dual-Mass Silicon Microgyroscope Mon, 15 Dec 2014 12:54:22 +0000 Frequency tuning of work modes in the silicon vibratory gyroscope is studied by the theoretical, numerical, and experimental methods in this paper. First, the schematic structure and simplified kinematics model of the gyroscope were presented for deducing the natural frequencies. Then, the width and length of support beams were optimized to tune work frequencies at their designed value. Besides, the frequency difference was experimentally tested and manually tuned by varying the voltage applied on the tuning capacitors. The test on a prototype showed that the difference could be localized between −55.8 Hz and 160.2 Hz when the tuning voltage limit is 20 V. Finally, a frequency control loop was developed to automatically tune the sense frequency toward the drive frequency. Both the theoretical analysis and numeric simulation show that the difference is stabilized at 0.8 Hz when no Coriolis force or quadrature coupling force is applied. It is proved that the frequency difference is successfully tuned by modifying the size of support beams before fabrication as well as the voltage applied on the tuning capacitors after fabrication. The automatic tuning loop, used to match the work modes, is beneficial to enhance the performance of the gyroscope as well as its resistance to environment disturbances. Lu Xu, Hongsheng Li, Yunfang Ni, Jia Liu, and Libin Huang Copyright © 2014 Lu Xu et al. All rights reserved. BeTrust: A Dynamic Trust Model Based on Bayesian Inference and Tsallis Entropy for Medical Sensor Networks Wed, 03 Dec 2014 00:10:12 +0000 With the rapid development and application of medical sensor networks, the security has become a big challenge to be resolved. Trust mechanism as a method of “soft security” has been proposed to guarantee the network security. Trust models to compute the trustworthiness of single node and each path are constructed, respectively, in this paper. For the trust relationship between nodes, trust value in every interval is quantified based on Bayesian inference. A node estimates the parameters of prior distribution by using the collected recommendation information and obtains the posterior distribution combined with direct interactions. Further, the weights of trust values are allocated through using the ordered weighted vector twice and overall trust degree is represented. With the associated properties of Tsallis entropy, the definition of path Tsallis entropy is put forward, which can comprehensively measure the uncertainty of each path. Then a method to calculate the credibility of each path is derived. The simulation results show that the proposed models can correctly reflect the dynamic of node behavior, quickly identify the malicious attacks, and effectively avoid such path containing low-trust nodes so as to enhance the robustness. Yan Gao and Wenfen Liu Copyright © 2014 Yan Gao and Wenfen Liu. All rights reserved. Boundary Detection Method for Large-Scale Coverage Holes in Wireless Sensor Network Based on Minimum Critical Threshold Constraint Mon, 01 Dec 2014 06:50:45 +0000 The existing coverage hole boundary detection methods cannot detect large-scale coverage hole boundary in wireless sensor network quickly and efficiently. Aiming at this problem, a boundary detection method for large-scale coverage holes in wireless sensor network based on minimum critical threshold constraint is proposed. Firstly, the optimization problem of minimum critical threshold is highlighted, and its formulaic description is constructed according to probabilistic sensing model. On the basis of this, the distributed gradient information is used to approximately solve the optimization problem. After that, local-scale rough boundary detection algorithm incorporating the minimum critical threshold and its iterative thinning algorithm are proposed according to blocking flow theory. The experimental results show that the proposed method has low computational complexity and network overhead when detecting large-scale coverage hole boundary in wireless sensor network. Rong Jing, Lingfu Kong, and Liang Kong Copyright © 2014 Rong Jing et al. All rights reserved. TDAL: Thoroughly Data Aggregation of Low Energy Devices in Secure Heterogeneous Wireless Sensor Networks Thu, 27 Nov 2014 12:35:30 +0000 The heterogeneous wireless sensor networks (HWSNs), composed of multiple types of tiny devices (sensor nodes) with wireless communication capability and suffering from computational resources constrains, enable interacting with the physical world, like never before. Innovative applications are developed for security, industrial production, monitoring, and tracking, but theoretical assumptions on these distributed data may not hold in a real scenario. In this paper, the emphasis is on accurate data and sensor nodes privacy preserving while transmitting their sensory information amongst neighbors toward the sink based on parent-child relationship in the wireless sensor network (WSN) environment, while ensuring energy saving. Data aggregation is a known energy efficient technique that is investigated through in-depth analysis of sensor communication through game theory, considering various embodiments of methods like elliptic curve cryptography for secrecy between nodes. This paper endeavors to provide new perspective for secure and energy efficient data aggregation models, where the heterogeneity of a sensor network environment makes it more complex to predict the overall network outputs. Tristan Daladier Engouang, Yun Liu, and Zhenjiang Zhang Copyright © 2014 Tristan Daladier Engouang et al. All rights reserved. Long-Stroke Nanopositioning Stage Driven by Piezoelectric Motor Mon, 24 Nov 2014 08:34:02 +0000 This paper reported a biaxial nanopositioning stage single-driven by piezoelectric motor. The employed piezoelectric motor can perform two different driving modes, namely, AC drive mode to drive in long-stroke and at high-speed and DC scanning mode with the high-resolution of several nanometers, which satisfies the requirements of both long-stroke and nanoresolution. To compensate for the effects of the variable friction force and some unpredictable disturbances, a novel backward error compensation (BEC) positioning control method integrated of the two driving modes and a double closed-loop PID controller system are proposed to obtain a high-accuracy positional motion. The experiment results demonstrate that the nanopositioning stage with large travel range of 300 mm × 300 mm has a fine speed characteristic and resolution is 5 nm. In the experiments of different travels up to 15 mm, calibrated by a commercial laser vibrometer, the positioning accuracy is proved within 55 nm in x-axis and 40 nm in y-axis with standard deviation less than 40 nm in x-axis and 30 nm in y-axis and the final position locking can be limited to 10 nm, meeting the requirements of micromanipulation technology. Yong Wang, Fujun Sun, Junhui Zhu, Ming Pang, and Changhai Ru Copyright © 2014 Yong Wang et al. All rights reserved. FPGA Based Single Chip Solution with 1-Wire Protocol for the Design of Smart Sensor Nodes Sun, 23 Nov 2014 08:18:16 +0000 Applications that involve monitoring of water quality parameters require measuring devices to be placed at different geographical locations but are controlled centrally at a remote site. The measuring devices in such applications need to be small, consume low power, and must be capable of local processing tasks facilitating the mobility to span the measuring area in a vast geographic area. This paper presents the design of a generalized, low-cost, reconfigurable, reprogrammable smart sensor node using a ZigBee with a Field-Programmable Gate Array (FPGA) that embeds all processing and communication functionalities based on the IEEE 1451 family of standards. Design of the sensor nodes includes processing and transducer control functionalities in a single core increasing the speedup of processing power due to interprocess communication taking place within the chip itself. Results obtained by measuring the pH value and temperature of water samples verify the performance of the proposed sensor node. M. D. R. Perera, R. G. N. Meegama, and M. K. Jayananda Copyright © 2014 M. D. R. Perera et al. All rights reserved. A Portable Random Key Predistribution Scheme for Distributed Sensor Network Mon, 17 Nov 2014 09:53:40 +0000 A distributed sensor network (DSN) can be deployed to collect information for military or civilian applications. However, due to the characteristics of DSNs such as limited power, key distribution for a distributed sensor network is complex. In this paper, a neighbor-based path key establishing method and a seed-based algorithm are put forward to improve the original random key pre-distribution scheme. The new scheme is portable because it is independent of the routing protocol. Moreover, the connectivity of the entire network also approaches 1. In particular, the new scheme can keep high connectivity by setting a small amount of redundancy in parameter values when the number of neighbors drops because of the node dormancy or death. The resilience against node capture in our scheme is not lower than that in the -path scheme and the basic schemes when the number of hops in a path is larger than 5, and the simulation result shows that the efficiency of our scheme is also slightly higher. Shihui Zheng, Yuan Tian, Lei Jin, and Yu Yang Copyright © 2014 Shihui Zheng et al. All rights reserved. Effect of a Non-Newtonian Load on Signature for Quartz Crystal Microbalance Measurements Thu, 13 Nov 2014 07:04:59 +0000 The quartz crystal microbalance (QCM) is increasingly used for monitoring the interfacial interaction between surfaces and macromolecules such as biomaterials, polymers, and metals. Recent QCM applications deal with several types of liquids with various viscous macromolecule compounds, which behave differently from Newtonian liquids. To properly monitor such interactions, it is crucial to understand the influence of the non-Newtonian fluid on the QCM measurement response. As a quantitative indicator of non-Newtonian behavior, we used the quartz resonator signature, , of the QCM measurement response, which has a consistent value for Newtonian fluids. We then modified De Kee’s non-Newtonian three-parameter model to apply it to our prediction of values for non-Newtonian liquids. As a model, we chose polyethylene glycol (PEG400) with the titration of its volume concentration in deionized water. As the volume concentration of PEG400 increased, the value decreased, confirming that the modified De Kee’s three-parameter model can predict the change in value. Collectively, the findings presented herein enable the application of the quartz resonator signature, , to verify QCM measurement analysis in relation to a wide range of experimental subjects that may exhibit non-Newtonian behavior, including polymers and biomaterials. Jae-Hyeok Choi, Kay K. Kanazawa, and Nam-Joon Cho Copyright © 2014 Jae-Hyeok Choi et al. All rights reserved. Using Capacitance Sensor to Extract Characteristic Signals of Dozing from Skin Surface Thu, 13 Nov 2014 06:57:28 +0000 Skin is the largest organ of the human body and a physiological structure that is directly exposed to the environment. From a theoretical perspective, numerous physiological and psychological signals use the skin as a medium for input and output with the outside world. Therefore, the skin is considered an optimal signal interception point when developing noninvasive, direct, and rapid signal exploration devices. To date, skin signal interceptions are predominantly performed by measuring skin impedance. However, this method is prone to interference such as sweat secretion, salt accumulation on the skin, and muscle contractions, which may result in a substantial amount of interference and erroneous results. The present study proposes novel and effective methods for skin signal interception, such as using a nested probe as a sensor to measure capacitance to be further processed as physiological and psychological signals. The experimental results indicate that the capacitance curve for the transition between wakefulness and dozing exhibits significant changes. This change in the curve can be analyzed by computer programs to clearly and rapidly determine whether the subject has entered the initial phases of sleep. Po-Ying Chen, Chi-Chang Chen, Wen-Kuan Yeh, Yukan Chang, Der-Chen Huang, Shyr-Shen Yu, Chwei-Shyong Tsai, Yu-Jung Huang, Wei-Cheng Lin, Shao-I Chu, Chung-Long Pan, Tsung-Hung Lin, and Shyh-Chang Liu Copyright © 2014 Po-Ying Chen et al. All rights reserved. Development of Prototype Laboratory Setup for Selective Detection of Ethylene Based on Multiwalled Carbon Nanotubes Thu, 06 Nov 2014 07:15:55 +0000 We report here a prototype laboratory setup for detecting ethylene (C2H4) in ppm level employing a sensor made of multiwalled carbon nanotubes of 40 nm average tube diameter. The proposed reversible chemoresistive ethylene sensor is fabricated using Kapton as the substrate onto which carbon nanotubes are coated using thick film technology. IDT silver electrodes are printed using piezo head based ink-jet printing technology. The increases in electrical resistance of the sensor element are measured on exposure to ethylene for different ethylene concentrations using a potentiostat and data acquisition system. The increase in resistance of the calibrated sensor element on exposure to ethylene (analyte) is about 18.4% at room temperature for 50 ppm ethylene concentration. This change is reversible. Our sensor element exhibits a better performance than those reported earlier (1.8%) and it has got the rise and fall time of 10 s and 60 s, respectively. It could be used for testing the ripening of fruits. J. Kathirvelan and R. Vijayaraghavan Copyright © 2014 J. Kathirvelan and R. Vijayaraghavan. All rights reserved. A Hybrid Structural Health Monitoring System for the Detection and Localization of Damage in Composite Structures Wed, 29 Oct 2014 12:11:00 +0000 A hybrid structural health monitoring (SHM) system, consisting of a piezoelectric transducer and fiber optic sensors (FOS) for generating and monitoring Lamb waves, was investigated to determine their potential for damage detection and localization in composite aerospace structures. As part of this study, the proposed hybrid SHM system, together with an in-house developed algorithm, was evaluated to detect and localize two types of damage: a through thickness damage (hole of 2 mm in diameter) and a surface damage (2 mm diameter bore hole with a depth of 0.65 mm) located on the backside of the plate. The experiments were performed using an aircraft representative composite plate skin, manufactured from carbon fiber reinforced polymer (CFRP). Darun Barazanchy, Marcias Martinez, Bruno Rocha, and Marko Yanishevsky Copyright © 2014 Darun Barazanchy et al. All rights reserved. TerraSAR-X StripMap Data Interpretation of Complex Urban Scenarios with 3D SAR Tomography Wed, 29 Oct 2014 08:26:16 +0000 The severe layover problem of complex urban scenarios in SAR data makes SAR data interpretation very difficult, especially for nonexperts. In this paper, we use 3D SAR tomography for SAR data interpretation of dense urban areas. An efficient and robust approach named Butterworth-filter based singular value decomposition (BSVD) is used for tomographic analysis. Two typical dense urban areas of interest located in Shanghai are analyzed. The tomographic results could help users to better understand the backscattering scenario. The experimental results indicate that SAR tomography is a promising and effective way to facilitate SAR data interpretation of complex urban areas. Lianhuan Wei, Timo Balz, Mingsheng Liao, and Lu Zhang Copyright © 2014 Lianhuan Wei et al. All rights reserved. Multimedia Fusion for Public Security in Heterogeneous Sensor Networks Mon, 27 Oct 2014 00:00:00 +0000 Public security is a widespread disastrous phenomenon that constitutes a grave threat. Although information fusion of video sensor networks for public security has been studied extensively, multimedia fusion in heterogeneous sensor networks or its application in public security remains a challenge and central goal in the field of information fusion. In this study, to realize the detection, monitoring, and intelligent alarm of such hazards, we develop a graph-based real-time schema for studying the dynamic structure of heterogeneous sensors for public security. In the proposed schema, data fusion algorithms based on data-driven aspects of fusion are explored to locate the optimal sensing ranges of sensor nodes in a network with heterogeneous targets. In addition, we propose a framework incorporating useful contextual and temporal cues for public security alarm, explore its conceptualizations, benefits, and challenges, and analyze the correlations of the target motion elements in the multimedia sensor stream. The experimental results show that the new method offers a better way of intelligent alarm that cannot be achieved by existing schemes. Jiangfan Feng, Wenwen Zhou, and Kaixin Sun Copyright © 2014 Jiangfan Feng et al. All rights reserved. An Improved FastSLAM System Based on Distributed Structure for Autonomous Robot Navigation Mon, 27 Oct 2014 00:00:00 +0000 Fast simultaneous localization and mapping (FastSLAM) is an efficient algorithm for autonomous navigation of mobile vehicle. However, FastSLAM must reconfigure the entire vehicle state equation when the feature points change, which causes an exponential growth in quantities of computation and difficulties in isolating potential faults. In order to overcome these limitations, an improved FastSLAM, based on the distributed structure, is developed in this paper. There are two state estimation parts designed in this improved FastSLAM. Firstly, a distributed unscented particle filter is used to avoid reconfiguring the entire system equation in the vehicle state estimation part. Secondly, in the landmarks estimation part, the observation model is designed as a linear one to update the landmarks states by using the linear observation errors. Then, the convergence of the proposed and improved FastSLAM algorithm is given in the sense of mean square. Finally, the simulation results show that the proposed distributed algorithm could reduce the computational complexity with high accuracy and high fault-tolerance performance. Fu-jun Pei, Hao-yang Li, and Yu-hang Cheng Copyright © 2014 Fu-jun Pei et al. All rights reserved. Live-Load Testing Application Using a Wireless Sensor System and Finite-Element Model Analysis of an Integral Abutment Concrete Girder Bridge Thu, 23 Oct 2014 11:29:06 +0000 As part of an investigation on the performance of integral abutment bridges, a single-span, integral abutment, prestressed concrete girder bridge near Perry, Utah was instrumented for live-load testing. The live-load test included driving trucks at 2.24 m/s (5 mph) along predetermined load paths and measuring the corresponding strain and deflection. The measured data was used to validate a finite-element model (FEM) of the bridge. The model showed that the integral abutments were behaving as 94% of a fixed-fixed support. Live-load distribution factors were obtained using this validated model and compared to those calculated in accordance to recommended procedures provided in the AASHTO LRFD Bridge Design Specifications (2010). The results indicated that if the bridge was considered simply supported, the AASHTO LRFD Specification distribution factors were conservative (in comparison to the FEM results). These conservative distribution factors, along with the initial simply supported design assumption resulted in a very conservative bridge design. In addition, a parametric study was conducted by modifying various bridge properties of the validated bridge model, one at a time, in order to investigate the influence that individual changes in span length, deck thickness, edge distance, skew, and fixity had on live-load distribution. The results showed that the bridge properties with the largest influence on bridge live-load distribution were fixity, skew, and changes in edge distance. Robert W. Fausett, Paul J. Barr, and Marvin W. Halling Copyright © 2014 Robert W. Fausett et al. All rights reserved. An Integrated Denoising Method for Sensor Mixed Noises Based on Wavelet Packet Transform and Energy-Correlation Analysis Mon, 20 Oct 2014 08:31:51 +0000 In order to solve the problem of industrial sensor signal denoising, an integrated denoising method for sensor mixed noises based on wavelet packet transform and energy-correlation analysis is proposed. The architecture of proposed method is designed and the key technologies, such as wavelet packet transformation, energy-correlation analysis, and processing method of wavelet packet coefficients based on energy-correlation analysis, are presented. Finally, a simulation example for a specific signal and an application of shearer cutting current signal, which mainly contain white Gaussian noise and impact noise, are carried out, and the simulation and application results show that the proposed method is effective and is outperforming others. Chao Tan, Yanping Wang, Xin Zhou, Zhongbin Wang, Lin Zhang, and Xinhua Liu Copyright © 2014 Chao Tan et al. All rights reserved. Depth Measurement Based on Infrared Coded Structured Light Sun, 19 Oct 2014 11:28:08 +0000 Depth measurement is a challenging problem in computer vision research. In this study, we first design a new grid pattern and develop a sequence coding and decoding algorithm to process the pattern. Second, we propose a linear fitting algorithm to derive the linear relationship between the object depth and pixel shift. Third, we obtain depth information on an object based on this linear relationship. Moreover, 3D reconstruction is implemented based on Delaunay triangulation algorithm. Finally, we utilize the regularity of the error curves to correct the system errors and improve the measurement accuracy. The experimental results show that the accuracy of depth measurement is related to the step length of moving object. Tong Jia, ZhongXuan Zhou, and HaiHong Gao Copyright © 2014 Tong Jia et al. All rights reserved.