Journal of Sensors http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . 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 http://www.hindawi.com/journals/js/2014/109403/ 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 http://www.hindawi.com/journals/js/2014/386753/ 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. An Improved FastSLAM System Based on Distributed Structure for Autonomous Robot Navigation Mon, 27 Oct 2014 00:00:00 +0000 http://www.hindawi.com/journals/js/2014/456289/ 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. Multimedia Fusion for Public Security in Heterogeneous Sensor Networks Mon, 27 Oct 2014 00:00:00 +0000 http://www.hindawi.com/journals/js/2014/273210/ 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. 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 http://www.hindawi.com/journals/js/2014/859486/ 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 http://www.hindawi.com/journals/js/2014/650891/ 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 http://www.hindawi.com/journals/js/2014/852621/ 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. An Efficient Data Collection Protocol Based on Multihop Routing and Single-Node Cooperation in Wireless Sensor Networks Wed, 15 Oct 2014 11:25:30 +0000 http://www.hindawi.com/journals/js/2014/186806/ Considering the constrained resource and energy in wireless sensor networks, an efficient data collection protocol named ESCDD which adopts the multihop routing technology and the single-node selection cooperative communication is proposed to make the communication protocol more simple and easy to realize for the large-scale multihop wireless sensor networks. ESCDD uses the greedy strategy and the control information based on RTS/CTS to select forwarding nodes. Then, the hops in the multihop data transmission are reduced. Based on the power control in physical layer and the control frame called CoTS in MAC layer, ESCDD chooses a single cooperative node to perform cooperative transmission. The receiving node adopts maximal ratio combining (MRC) to recover original data. The energy consumption per hop is reduced. Furthermore, the total energy consumption in data collection process is shared by more nodes and the network lifetime is extended. Compared with GeRaF, EERNFS, and REEFG protocol, the simulation results show that ESCDD can effectively reduce the average delay of multihop data transmission, improve the successful delivery rate of data packets, significantly save the energy consumption of network nodes, and make the energy consumption more balanced. Guoqiang Zheng, Bing Li, Jishun Li, Huahong Ma, and Baofeng Ji Copyright © 2014 Guoqiang Zheng et al. All rights reserved. Design of a UHF Antenna for Partial Discharge Detection of Power Equipment Wed, 15 Oct 2014 08:48:46 +0000 http://www.hindawi.com/journals/js/2014/839386/ A single-arm Archimedean spiral antenna that can be directly fed by a 50  coaxial cable is investigated in this study. Every antenna parameter is optimized under simulation to make the antenna work in the ultra-high frequency band. The influence of dielectric materials, feed cone angle, and antenna duty ratio is also examined. Partial discharge (PD) experiments on several typical artificial insulation defects are conducted, and a single-arm Archimedean spiral antenna and a typical microstrip antenna are utilized for PD measurement. The PD characteristics of different insulation defects are also analyzed. Results show that the designed antenna is suitable for ultra-high frequency monitoring. The detection sensitivity of the single-arm spiral antenna is superior to that of the ordinary microstrip antenna. The former can be utilized in wide-band measurement fields. Youyuan Wang, Junfeng Wu, Weigen Chen, and Yajun Wang Copyright © 2014 Youyuan Wang et al. All rights reserved. A Survey on Energy Efficient Wireless Sensor Networks for Bicycle Performance Monitoring Application Mon, 13 Oct 2014 11:41:01 +0000 http://www.hindawi.com/journals/js/2014/153604/ Wireless sensor networks (WSNs) have greatly advanced in the past few decades and are now widely used, especially for remote monitoring; the list of potential uses seems endless. Three types of wireless sensor technologies (Bluetooth, ZigBee, and ANT) have been used to monitor the biomechanical and physiological activities of bicycles and cyclists, respectively. However, the wireless monitoring of these activities has faced some challenges. The aim of this paper is to highlight various methodologies for monitoring cycling to provide an effective and efficient way to overcome the various challenges and limitations of sports cycling using wireless sensor interfaces. Several design criteria were reviewed and compared with different solutions for the implementation of current WSN research, such as low power consumption, long distance communications, small size, and light weight. Conclusions were drawn after observing the example of an advanced and adaptive network technology (ANT) network highlighting reduced power consumption and prolonged battery life. The power saving achieved in the slave node was 88–95% compared to the similar ANT protocol used in the medical rehabilitation. Sadik Kamel Gharghan, Rosdiadee Nordin, and Mahamod Ismail Copyright © 2014 Sadik Kamel Gharghan et al. All rights reserved. Surface Crack Detection for Carbon Fiber Reinforced Plastic Materials Using Pulsed Eddy Current Based on Rectangular Differential Probe Sun, 12 Oct 2014 11:45:13 +0000 http://www.hindawi.com/journals/js/2014/727269/ Aiming at the surface defect inspection of carbon fiber reinforced composite, the differential and the direct measurement finite element simulation models of pulsed eddy current flaw detection were built. The principle of differential pulsed eddy current detection was analyzed and the sensitivity of defect detection was compared through two kinds of measurements. The validity of simulation results was demonstrated by experiments. The simulation and experimental results show that the pulsed eddy current detection method based on rectangular differential probe can effectively improve the sensitivity of surface defect detection of carbon fiber reinforced composite material. Jialong Wu, Deqiang Zhou, and Jun Wang Copyright © 2014 Jialong Wu et al. All rights reserved. Estimation of Displacement and Rotation by Magnetic Tactile Sensor Using Stepwise Regression Analysis Sun, 12 Oct 2014 08:50:01 +0000 http://www.hindawi.com/journals/js/2014/459059/ The human is covered with soft skin and has tactile receptors inside. The skin deforms along a contact surface. The tactile receptors detect the mechanical deformation. The detection of the mechanical deformation is essential for the tactile sensation. We propose a magnetic type tactile sensor which has a soft surface and eight magnetoresistive elements. The soft surface has a permanent magnet inside and the magnetoresistive elements under the soft surface measure the magnetic flux density of the magnet. The tactile sensor estimates the displacement and the rotation on the surface based on the change of the magnetic flux density. Determination of an estimate equation is difficult because the displacement and the rotation are not geometrically decided based on the magnetic flux density. In this paper, a stepwise regression analysis determines the estimate equation. The outputs of the magnetoresistive elements are used as explanatory variables, and the three-axis displacement and the two-axis rotation are response variables in the regression analysis. We confirm the regression analysis is effective for determining the estimate equations through simulation and experiment. The results show the tactile sensor measures both the displacement and the rotation generated on the surface by using the determined equation. Hiroyuki Nakamoto, Taketo Wakabayashi, Futoshi Kobayashi, and Fumio Kojima Copyright © 2014 Hiroyuki Nakamoto et al. All rights reserved. Contactless Inductive Flow Tomography: Brief History and Recent Developments in Its Application to Continuous Casting Wed, 17 Sep 2014 10:46:16 +0000 http://www.hindawi.com/journals/js/2014/739161/ The contactless inductive flow tomography (CIFT) aims at reconstructing the velocity field of electrically conducting fluids, with special focus on applications in metallurgy and crystal growth technologies. The method relies on the induction of secondary magnetic fields if the moving fluid is exposed to a primary magnetic field. The theoretical foundation of the method is delineated, and some early experiments on the reconstruction of the three-dimensional flow in a cylinder are sketched. Then, the recent efforts to apply CIFT to various model problems in connection with the continuous casting of steel are summarized. Matthias Ratajczak, Thomas Gundrum, Frank Stefani, and Thomas Wondrak Copyright © 2014 Matthias Ratajczak et al. All rights reserved. Method of Combining Spectrophotometer and Optical Imaging Equipment to Extract Optical Parameters for Material Rendering Wed, 10 Sep 2014 16:55:48 +0000 http://www.hindawi.com/journals/js/2014/803710/ Optical parameters of materials are used for implementing cinematic rendering in the field of graphics. Critical elements for extracting these optical characteristics are the accuracy of the extracted parameters and the required time for extraction. In this paper, a novel method for improving these elements as well as a comparison to the existing methodology is presented. By using a spectrophotometer and custom designed optical imaging equipment (OIE), our method made it possible to enhance accuracy and accelerate computing speed by reducing the number of unknowns in the fitting equations. Further, we validated the superiority of the extracted optical characteristic parameters with a rendering simulation. Taeyoung Choi, Seonghee Lee, and Seongah Chin Copyright © 2014 Taeyoung Choi et al. All rights reserved. Hybrid Electronic Tongues Applied to the Quality Control of Wines Wed, 10 Sep 2014 07:45:40 +0000 http://www.hindawi.com/journals/js/2014/598317/ The legislation of food industry is becoming increasingly strict with regard to the quality of food products. Therefore, the market is demanding for automatic systems of analysis that allow fast and accurate monitoring of the evolution of quality parameters in agrofood products or permit obtaining information to optimize production processes. In this context, sensors and more specifically microsensors play an important role since they allow fast and reproducible measurement of a large number of quality parameters with good reliability and can be implemented in portable systems. This paper presents a review of the results obtained with an electronic tongue based on different kinds of microsensors applied to wine analysis by the team of IMB-CNM. This multisensor system allows on one hand classifying the wine according to its features like grape variety, geographic origin, year, and organoleptic characteristics and on the other hand quantifying some parameters of interest in quality control, such as alcoholic degree, pH, ions, total acidity, glycerol, and color. Manuel Gutiérrez-Capitán, Fina Capdevila, Jordi Vila-Planas, Carme Domingo, Stephanus Büttgenbach, Andreu Llobera, Anna Puig-Pujol, and Cecilia Jiménez-Jorquera Copyright © 2014 Manuel Gutiérrez-Capitán et al. All rights reserved. Implementation of Mobile Target Positioning Technology Integrating SINS with WSN Measurements Mon, 01 Sep 2014 07:43:21 +0000 http://www.hindawi.com/journals/js/2014/673179/ Accurate and robust positioning technology is expected to promote management level and service efficiency in various industrial applications. The strap-down inertial navigation system (SINS) approach has short-term accurate positioning performance, but the SINS is known for its accumulative error over time. Meanwhile, wireless sensor networks (WSN) approach can keep the mobile target on effective tracking after a long time monitoring, but the WSN may have large positioning error in certain areas. In order to make the positioning method allow profit from their advantages, this paper proposes a positioning technology using SINS approach in conjunction with WSN approach. The measurement parameters by SINS and WSN approaches are used. Then the SINS, anchor nodes, mobile tags, XBee, and computer are applied to design the positioning system. The estimation results indicate that the proposed method can make up for the shortcomings by pure SINS or WSN method and can be available for some accurate and robust applications. Chengming Luo, Wei Li, Hai Yang, Baohua Ying, and Gaifang Xin Copyright © 2014 Chengming Luo et al. All rights reserved. Research on an Improved Method for Permanent Magnet Synchronous Motor Mon, 01 Sep 2014 05:55:28 +0000 http://www.hindawi.com/journals/js/2014/816421/ In permanent magnet synchronous motor (PMSM) traditional vector control system, PI regulator is used in the speed loop, but it has some defects. An improved method of PMSM vector control is proposed in the paper. The active-disturbance rejection control (ADRC) speed regulator is designed with the input signals of given speed and real speed and the output of given stator current q coordinate component. Then, in order to optimize ADRC controller, the least squares support vector machines (LSSVM) optimal regression model is derived and successfully embedded in the ADRC controller. ADRC observation precision and dynamic response of the system are improved. The load disturbance effect on the system is reduced to a large extent. The system anti-interference ability is further improved. Finally, the current sensor CSNE151-100 is selected to sample PMSM stator currents. The voltage sensor JLBV1 is used to sample the stator voltage. The rotor speed of PMSM is measured by mechanical speed sensor, the type of which is BENTLY 330500. Experimental platform is constructed to verify the effectiveness of the proposed method. Yingpei Liu, Tao Gao, and Guo Li Copyright © 2014 Yingpei Liu et al. All rights reserved. Analysis on Structural Stress of 64 × 64 InSb IRFPAs with Temperature Dependent Elastic Underfill Tue, 26 Aug 2014 07:22:35 +0000 http://www.hindawi.com/journals/js/2014/952323/ To improve the reliability of InSb IRFPAs, underfill has usually been filled between InSb chip and Si ROIC. Around the glass transition temperature, underfill shows viscoelasticity, yet, far below it, which shows apparently temperature dependent mechanical properties. Basing on the temperature dependent elastic model of underfill, firstly a small format array of elements InSb IRFPAs is investigated by changing indium bump diameters and heights; simulated results show that the maximum stress in InSb chip has nothing to do with underfill height and is dependent on indium bump diameter; the varying tendency is just like the horizontally extended letter U. When indium bump diameter is set to 24 m with height 21  m, the maximal stress in InSb chip reaches minimum. To learn the stress in elements in short time, with the above optimal structure, InSb IRFPAs array scale is doubled once again from to elements. Simulation results show that the stress maximum in InSb chip is strongly determined by arrays format and increases with array scale; yet, the stress maximum in Si ROIC almost keeps constant and is independent on array sizes; besides, the largest stress locates in InSb chip, and the stress distribution in InSb chip is uniform. Liwen Zhang, Wei Tian, Qingduan Meng, Mengfang Sun, Na Li, and Zhen Lei Copyright © 2014 Liwen Zhang et al. All rights reserved. Two Measures for Enhancing Data Association Performance in SLAM Thu, 21 Aug 2014 09:04:03 +0000 http://www.hindawi.com/journals/js/2014/326820/ Data association is one of the key problems in the SLAM community. Several data association failures may cause the SLAM results to be divergent. Data association performance in SLAM is affected by both data association methods and sensor information. Two measures of handling sensor information are introduced herein to enhance data association performance in SLAM. For the first measure, truncating strategy of limited features, instead of all matched features, is used for observation update. These features are selected according to an information variable. This truncating strategy is used to lower the effect of false matched features. For the other measure, a special rejecting mechanism is designed to reject suspected observations. When the predicted robot pose is obviously different from the updated robot pose, all observed sensor information at this moment is discarded. The rejecting mechanism aims at eliminating accidental sensor information. Experimental results indicate that the introduced measures perform well in improving the stability of data association in SLAM. These measures are of extraordinary value for real SLAM applications. Wu Zhou, Xiaohong Yin, Zhenxin Cao, and Jinjun Shao Copyright © 2014 Wu Zhou et al. All rights reserved. Optimal Joint Allocation of MultiSlot Spectrum Sensing and Transfer Power in MultiChannel Cognitive Radio Thu, 21 Aug 2014 00:00:00 +0000 http://www.hindawi.com/journals/js/2014/494361/ In multichannel, cognitive radio (CR), the secondary user (SU) is allowed to utilize multiple subaltern frequency bands of the primary user (PU), when these bands, namely, subchannels are not currently being used. To support this spectrum reuse functionality, the SU is required to sense each subchannel, and only the subchannels wherein the PU is inactive are available for the spectrum access of the SU. In this paper, a multislot spectrum sensing and transfer scheme for multichannel CR is proposed, whose sensing stage is divided into several time slots allocated to the subchannels for spectrum sensing. While guaranteeing the spectrum sensing performance on each subchannel and limiting the interference to the PU, we formulate an optimization problem that maximizes the SU’s aggregate throughput by jointly allocating the optimal number of sensing time slots and the optimal transfer power to each subchannel. Theoretical analysis is given to prove the feasibility of the proposed optimization problem and simulation results are presented to show the notable improvement on the SU’s throughput when the sensing time slots and the transfer power are both optimized by the proposed scheme. Xin Liu, Min Jia, Xuemai Gu, Fanqiang Kong, and Qingfeng Jing Copyright © 2014 Xin Liu et al. All rights reserved. Detection of Adulteration in Argan Oil by Using an Electronic Nose and a Voltammetric Electronic Tongue Tue, 19 Aug 2014 09:53:37 +0000 http://www.hindawi.com/journals/js/2014/245831/ Adulteration detection of argan oil is one of the main aspects of its quality control. Following recent fraud scandals, it is mandatory to ensure product quality and customer protection. The aim of this study is to detect the percentages of adulteration of argan oil with sunflower oil by using the combination of a voltammetric e-tongue and an e-nose based on metal oxide semiconductor sensors and pattern recognition techniques. Data analysis is performed by three pattern recognition methods: principal component analysis (PCA), discriminant factor analysis (DFA), and support vector machines (SVMs). Excellent results were obtained in the differentiation between unadulterated and adulterated argan oil with sunflower one. To the best of our knowledge, this is the first attempt to demonstrate whether the combined e-nose and e-tongue technologies could be successfully applied to the detection of adulteration of argan oil. Madiha Bougrini, Khalid Tahri, Zouhair Haddi, Tarik Saidi, Nezha El Bari, and Benachir Bouchikhi Copyright © 2014 Madiha Bougrini et al. All rights reserved. A Gas Monitoring and Control System in a Coal and Gas Outburst Laboratory Tue, 19 Aug 2014 07:14:39 +0000 http://www.hindawi.com/journals/js/2014/172016/ Coal and gas outburst is a phenomenon characterized by the ejection of gas and coal from the solid face of a mine. Physical minioutburst experiments are a very important tool for analyzing outbursts of coal and gas. However, few reports have focused on the safety problem produced by gas concentration or the role of gas spread during the physical experiments. In this study, we designed a simple monitoring and control system for the safety of staff during the minioutburst experiments. The results showed that, in the simulation of four dangerous situations, the system based on a sensors feedback loop can monitor the development of gas content in the temporal and spatial domains for the enhancement of accurate warnings. The system also automatically chooses the appropriate ventilation measures to lower the gas content considering different degrees of danger. W. Nie, Y. Liu, C. J. Li, and J. Xu Copyright © 2014 W. Nie et al. All rights reserved. Adaptive Opportunistic Cooperative Control Mechanism Based on Combination Forecasting and Multilevel Sensing Technology of Sensors for Mobile Internet of Things Sun, 17 Aug 2014 08:33:46 +0000 http://www.hindawi.com/journals/js/2014/297368/ In mobile Internet of Things, there are many challenges, including sensing technology of sensors, how and when to join cooperative transmission, and how to select the cooperative sensors. To address these problems, we studied the combination forecasting based on the multilevel sensing technology of sensors, building upon which we proposed the adaptive opportunistic cooperative control mechanism based on the threshold values such as activity probability, distance, transmitting power, and number of relay sensors, in consideration of signal to noise ratio and outage probability. More importantly, the relay sensors would do self-test real time in order to judge whether to join the cooperative transmission, for maintaining the optimal cooperative transmission state with high performance. The mathematical analyses results show that the proposed adaptive opportunistic cooperative control approach could perform better in terms of throughput ratio, packet error rate and delay, and energy efficiency, compared with the direct transmission and opportunistic cooperative approaches. Yong Jin, Kaijian Xia, Xiaogang Ren, Jian Cai, and Hongchun Fan Copyright © 2014 Yong Jin et al. All rights reserved. Cluster Head Selection in a Homogeneous Wireless Sensor Network Ensuring Full Connectivity with Minimum Isolated Nodes Tue, 12 Aug 2014 11:47:25 +0000 http://www.hindawi.com/journals/js/2014/724219/ The research work proposes a cluster head selection algorithm for a wireless sensor network. A node can be a cluster head if it is connected to at least one unique neighbor node where the unique neighbor is the one that is not connected to any other node. If there is no connected unique node then the CH is selected on the basis of residual energy and the number of neighbor nodes. With the increase in number of clusters, the processing energy of the network increases; hence, this algorithm proposes minimum number of clusters which further leads to increased network lifetime. The major novel contribution of the proposed work is an algorithm that ensures a completely connected network with minimum number of isolated nodes. An isolated node will remain only if it is not within the transmission range of any other node. With the maximum connectivity, the coverage of the network is automatically maximized. The superiority of the proposed design is verified by simulation results done in MATLAB, where it clearly depicts that the total numbers of rounds before the network dies out are maximum compared to other existing protocols. Tapan Kumar Jain, Davinder Singh Saini, and Sunil Vidya Bhooshan Copyright © 2014 Tapan Kumar Jain et al. All rights reserved. Distributed Binary Quantization of a Noisy Source in Wireless Sensor Networks Tue, 12 Aug 2014 10:58:48 +0000 http://www.hindawi.com/journals/js/2014/368643/ In distributed (decentralized) estimation in wireless sensor networks, an unknown parameter must be estimated from some noisy measurements collected at different sensors. Due to limited communication resources, these measurements are typically quantized before being sent to a fusion center, where an estimation of the unknown parameter is calculated. In the most stringent condition, each measurement is converted to a single bit. In this study, we propose a distributed quantization scheme which is based on single-bit quantized data from each sensor and achieves high estimation accuracy at the fusion centre. We do this by designing some local binary quantizers which define a multithreshold quantization rule for each sensor. These local binary quantizers are initially designed so that together they mimic the functionality of a multilevel quantizer. Later, their design is improved to include some error-correcting capability, which further improves the estimation accuracy from the sensors’ binary data. The distributed quantization formed by such local binary quantizers along with the proper estimator proposed in this work achieves better performance, compared to the existing distributed binary quantization methods, specially when fewer sensors with low measurement noise are available. Sahar Movaghati and Masoud Ardakani Copyright © 2014 Sahar Movaghati and Masoud Ardakani. All rights reserved. Research on Nonlinear Dynamics of Drive Mode in Z-Axis Silicon Microgyroscope Mon, 11 Aug 2014 08:17:24 +0000 http://www.hindawi.com/journals/js/2014/801618/ A novel drive method is proposed to increase the vibration amplitude of drive mode of silicon vibratory gyroscopes based on the nonlinear dynamics research made in this paper. A nonlinear dynamic equation, considering the nonlinear mechanical-elastic and electrostatic force, was firstly deduced according to the simplified structure schematic of drive mode. Then, experiments were made to characterize the nonlinear amplitude-frequency response characteristic as well as its dependence on drive voltage. Besides, by solving the nondimensional nonlinear dynamics using Matlab and Simulink, the influence of initial status of drive mode, that is, the displacement and the velocity, on the stable vibration amplitude was presented. The amplitude-frequency characteristic was also analyzed by simulation. The result of simulation shows good agreement with that of experiments. When nonlinearity is present in the amplitude-frequency characteristic, there is a wide flat region with larger amplitude than the peak amplitude obtained in the linear characteristic. Finally, a novel drive method was presented to excite the nonlinear vibration of large amplitude in the downwards-sweeping characteristic curve. It is numerically proved that this merit can be utilized to enlarge the drive mode’s vibration amplitude so as to enhance silicon gyroscopes’ performance. Lu Xu, Hongsheng Li, Jia Liu, Yunfang Ni, and Libin Huang Copyright © 2014 Lu Xu et al. All rights reserved. SOFM Neural Network Based Hierarchical Topology Control for Wireless Sensor Networks Mon, 11 Aug 2014 08:00:23 +0000 http://www.hindawi.com/journals/js/2014/121278/ Well-designed network topology provides vital support for routing, data fusion, and target tracking in wireless sensor networks (WSNs). Self-organization feature map (SOFM) neural network is a major branch of artificial neural networks, which has self-organizing and self-learning features. In this paper, we propose a cluster-based topology control algorithm for WSNs, named SOFMHTC, which uses SOFM neural network to form a hierarchical network structure, completes cluster head selection by the competitive learning among nodes, and takes the node residual energy and the distance to the neighbor nodes into account in the clustering process. In addition, the approach of dynamically adjusting the transmitting power of the cluster head nodes is adopted to optimize the network topology. Simulation results show that SOFMHTC may get a better energy-efficient performance and make more balanced energy consumption compared with some existing algorithms in WSNs. Zhi Chen, Shuai Li, and Wenjing Yue Copyright © 2014 Zhi Chen et al. All rights reserved. Mutton Traceability Method Based on Internet of Things Sun, 10 Aug 2014 06:54:19 +0000 http://www.hindawi.com/journals/js/2014/506580/ In order to improve the mutton traceability efficiency for Internet of Things and solve the problem of data transmission, analyzed existing tracking algorithm, proposed the food traceability application model, Petri network model of food traceability and food traceability of time series data of improved K-means algorithm based on the Internet of things. The food traceability application model to convert, integrate and mine the heterogeneous information, implementation of the food safety traceability information management, Petri network model for food traceability in the process of the state transition were analyzed and simulated and provides a theoretical basis to study the behavior described in the food traceability system and structural design. The experiments on simulation data show that the proposed traceability method based on Internet of Things is more effective for mutton traceability data than the traditional K-means methods. Wu Min-Ning, Zhang-Xing Li, Zhang Yong-Heng, and Zhang Feng Copyright © 2014 Wu Min-Ning et al. All rights reserved. Modeling FOG Drift Using Back-Propagation Neural Network Optimized by Artificial Fish Swarm Algorithm Mon, 04 Aug 2014 09:29:09 +0000 http://www.hindawi.com/journals/js/2014/273043/ Based on the temperature drift characteristic of fiber optic gyroscope (FOG), a novel modeling and compensation method which integrated the artificial fish swarm algorithm (AFSA) and back-propagation (BP) neural network is proposed to improve the output accuracy of FOG and the precision of inertial navigation system. In this paper, AFSA is used to optimize the weights and threshold of BP neural network which determine precision of the model directly. In order to verify the effectiveness of the proposed algorithm, the predicted results of BP optimized by genetic algorithm (GA) and AFSA are compared and a quantitative evaluation of compensation results is analyzed by Allan variance. The comparison result illustrated the main error sources and the sinusoidal noises in the FOG output signal are reduced by about 50%. Therefore, the proposed modeling method can be used to improve the FOG precision. Rui Song, Xiyuan Chen, Chong Shen, and Hong Zhang Copyright © 2014 Rui Song et al. All rights reserved. Intercomparison of Methods for Determination of Resonant Frequency Shift of a Microstrip Patch Antenna Loaded with Hevea Rubber Latex Sun, 03 Aug 2014 06:40:35 +0000 http://www.hindawi.com/journals/js/2014/656972/ This paper presents an intercomparison between the finite element method, method of moment, and the variational method to determine the effect of moisture content on the resonant frequency shift of a microstrip patch loaded with wet material. The samples selected for this study were Hevea rubber latex with different percentages of moisture content from 35% to 85%. The results were compared with the measurement data in the frequency range between 1 GHz and 4 GHz. It was found that the finite element method is the most accurate among all the three computational techniques with 0.1 mean error when compared to the measured resonant frequency shift. A calibration equation was obtained to predict moisture content from the measured frequency shift with an accuracy of 2%. Nor Zakiah Yahaya, Zulkifly Abbas, Borhanuddin Mohd Ali, Alif Ismail, and Farizah Ansarudin Copyright © 2014 Nor Zakiah Yahaya et al. All rights reserved.