Journal of Sensors http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Linear Time Approximation Algorithms for the Relay Node Placement Problem in Wireless Sensor Networks with Hexagon Tessellation Sun, 03 May 2015 12:21:47 +0000 http://www.hindawi.com/journals/js/2015/565983/ The relay node placement problem in wireless sensor network (WSN) aims at deploying the minimum number of relay nodes over the network so that each sensor can communicate with at least one relay node. When the deployed relay nodes are homogeneous and their communication ranges are circular, one way to solve the WSN relay node placement problem is to solve the minimum geometric disk cover (MGDC) problem first and place the relay nodes at the centers of the covering disks and then, if necessary, deploy additional relay nodes to meet the connection requirement of relay nodes. It is known that the MGDC problem is NP-complete. A novel linear time approximation algorithm for the MGDC problem is proposed, which identifies covering disks using the regular hexagon tessellation of the plane with bounded area. The approximation ratio of the proposed algorithm is (), where . Experimental results show that the worst case is rare, and on average the proposed algorithm uses less than 1.7 times the optimal disks of the MGDC problem. In cases where quick deployment is necessary, this study provides a fast 7-approximation algorithm which uses on average less than twice the optimal number of relay nodes in the simulation. Chi-Chang Chen, Chi-Yu Chang, and Po-Ying Chen Copyright © 2015 Chi-Chang Chen et al. All rights reserved. A Method of Vehicle Route Prediction Based on Social Network Analysis Thu, 30 Apr 2015 13:47:55 +0000 http://www.hindawi.com/journals/js/2015/210298/ A method of vehicle route prediction based on social network analysis is proposed in this paper. The difference from proposed work is that, according to our collected vehicles’ past trips, we build a relationship model between different road segments rather than find the driving regularity of vehicles to predict upcoming routes. In this paper, firstly we depend on graph theory to build an initial road network model and modify related model parameters based on the collected data set. Then we transform the model into a matrix. Secondly, two concepts from social network analysis are introduced to describe the meaning of the matrix and we process it by current software of social network analysis. Thirdly, we design the algorithm of vehicle route prediction based on the above processing results. Finally, we use the leave-one-out approach to verify the efficiency of our algorithm. Ning Ye, Zhong-qin Wang, Reza Malekian, Ying-ya Zhang, and Ru-chuan Wang Copyright © 2015 Ning Ye et al. All rights reserved. Development of In Situ Sensors for Chlorophyll Concentration Measurement Thu, 30 Apr 2015 11:40:08 +0000 http://www.hindawi.com/journals/js/2015/903509/ Chlorophyll fluorescence measurement is a sensitive and effective method to quantify and analyze freshwater and sea water phytoplankton in situ. Major improvements in optical design, electronic technology, and calibration protocol have increased the accuracy and reliability of the fluorometer. This review briefly describes the improvement of probe design, excitation light sources, detectors, and calibrations of in situ fluorometers. Firstly, various optical designs for increasing the efficiency of fluorescence measurement are discussed. Next, the development of electronic technology to meet and improve in situ measurement, including various light sources, detectors, and corresponding measurement protocols, is described. In addition, various calibration materials, procedures, and methods are recommended for different kinds of water. The conclusion discusses key trends and future perspectives for in situ fluorescence sensors. Lihua Zeng and Daoliang Li Copyright © 2015 Lihua Zeng and Daoliang Li. All rights reserved. An Efficient Bypassing Void Routing Algorithm for Wireless Sensor Network Thu, 30 Apr 2015 11:07:00 +0000 http://www.hindawi.com/journals/js/2015/686809/ Since the sensor node’s distribution in a wireless sensor network (WSN) is irregular, geographic routing protocols using the greedy algorithm can cause local minima problem. This problem may fail due to routing voids and lead to failure of data transmission. Based on the virtual coordinate mapping, this paper proposes an efficient bypassing void routing protocol to solve the control packet overhead and transmission delay in routing void of WSN, which is called EBVRPVCM. The basic idea is to transfer the random structure of void edge to a regular one through mapping the coordinates on a virtual circle. In EBVRPVCM, some strategies, executed in different regions, are selected through virtual coordinates to bypass routing void efficiently. The regular edge is established by coordinate mapping that can shorten the average routing path length and decrease the transmission delay. The virtual coordinate mapping is not affected by the real geographic node position, and the control packet overhead can be reduced accordingly. Compared with RGP and GPSR, simulation results demonstrate that EBVRPVCM can successfully find the shortest routing path with higher delivery ratio and less control packet overhead and energy consumption. Xunli Fan and Feifei Du Copyright © 2015 Xunli Fan and Feifei Du. All rights reserved. Variable Step-Size Method Based on a Reference Separation System for Source Separation Thu, 30 Apr 2015 09:35:57 +0000 http://www.hindawi.com/journals/js/2015/964098/ Traditional variable step-size methods are effective to solve the problem of choosing step-size in adaptive blind source separation process. But the initial setting of learning rate is vital, and the convergence speed is still low. This paper proposes a novel variable step-size method based on reference separation system for online blind source separation. The correlation between the estimated source signals and original source signals increases along with iteration. Therefore, we introduce a reference separation system to approximately estimate the correlation in terms of mean square error (MSE), which is utilized to update the step-size. The use of “minibatches” for the computation of MSE can reduce the complexity of the algorithm to some extent. Moreover, simulations demonstrate that the proposed method exhibits superior convergence and better steady-state performance over the fixed step-size method in the noise-free case, while converging faster than classical variable step-size methods in both stationary and nonstationary environments. Pengcheng Xu, Zhigang Yuan, Wei Jian, and Wei Zhao Copyright © 2015 Pengcheng Xu et al. All rights reserved. A Framework for Real Time Processing of Sensor Data in the Cloud Wed, 29 Apr 2015 06:49:39 +0000 http://www.hindawi.com/journals/js/2015/468047/ We describe IoTCloud, a platform to connect smart devices to cloud services for real time data processing and control. A device connected to IoTCloud can communicate with real time data analysis frameworks deployed in the cloud via messaging. The platform design is scalable in connecting devices as well as transferring and processing data. With IoTCloud, a user can develop real time data processing algorithms in an abstract framework without concern for the underlying details of how the data is distributed and transferred. For this platform, we primarily consider real time robotics applications such as autonomous robot navigation, where there are strict requirements on processing latency and demand for scalable processing. To demonstrate the effectiveness of the system, a robotic application is developed on top of the framework. The system and the robotics application characteristics are measured to show that data processing in central servers is feasible for real time sensor applications. Supun Kamburugamuve, Leif Christiansen, and Geoffrey Fox Copyright © 2015 Supun Kamburugamuve et al. All rights reserved. Cost-Effective Location Management for Mobile Agents on the Internet Tue, 28 Apr 2015 13:13:32 +0000 http://www.hindawi.com/journals/js/2015/915648/ Many mobile agent system-related services and applications require interacting with a mobile agent by passing messages. However, an agent’s mobility raises several challenges in delivering messages to a mobile agent accurately. Consisting of tracking and message delivery phases, most mobile agent location management schemes create or receive many update messages and interaction messages to ensure the effectiveness of the schemes. In addition to downgrading the overall performance of a mobile agent location management scheme, excessive transmission of messages increases the network load. The migration locality of a mobile agent and the interaction rate between mobile agents significantly affect the performance of a mobile agent location management scheme with respect to location management cost. This work presents a novel Dual Home based Scheme (DHS) that can lower the location management costs in terms of migration locality and interaction rate. While the DHS scheme uniquely adopts dual home location management architecture, a selective update strategy based on that architecture is also designed for cost-effective location management of mobile agents. Moreover, DHS is compared with available schemes based on formulations and simulation experiments from the perspective of location management costs. Simulation results demonstrate that the proposed DHS scheme performs satisfactorily in terms of migration locality and interaction rate. Chien-Sheng Chen, Jiing-Dong Hwang, Chyuan-Der Lu, and Ting-Yuan Yeh Copyright © 2015 Chien-Sheng Chen et al. All rights reserved. A Novel Method of Adaptive Traffic Image Enhancement for Complex Environments Tue, 28 Apr 2015 07:08:42 +0000 http://www.hindawi.com/journals/js/2015/516326/ There exist two main drawbacks for traffic images in classic image enhancement methods. First is the performance degradation that occurs under frontlight, backlight, and extremely dark conditions. The second drawback is complicated manual settings, such as transform functions and multiple parameter selection mechanisms. Thus, this paper proposes an effective and adaptive parameter optimization enhancement algorithm based on adaptive brightness baseline drift (ABBD) for color traffic images under different luminance conditions. This method consists of two parts: brightness baseline model acquisition and adaptive color image compensation. The brightness baseline model can be attained by analyzing changes in light along a timeline. The adaptive color image compensation involves color space remapping and adaptive compensation specific color components. Our experiments were tested on various traffic images under frontlight, backlight, and during nighttime. The experimental results show that the proposed method achieved better effects compared with other available methods under different luminance conditions, which also effectively reduced the influence of the weather. Cao Liu, Hong Zheng, Dian Yu, and Xiaohang Xu Copyright © 2015 Cao Liu et al. All rights reserved. Study of the Effect of Damage on the Electrical Impedance of Carbon Nanotube Reinforced Epoxy Nanocomposites Mon, 27 Apr 2015 09:11:10 +0000 http://www.hindawi.com/journals/js/2015/805303/ Within the scope of this work is the study of the effect of damage on the electrical hysteretic behaviour of carbon nanotube (CNT) reinforced epoxy nanocomposites. For that purpose CNT reinforced epoxy nanocomposites were subjected to different levels of damage and their response to an AC voltage excitation was monitored. The correlation between frequency dependent impedance properties and level of damage was extensively studied. The AC frequency response of the interrogated specimens from 10 Hz up to 0.5 MHz revealed a strong correlation between the level of damage and the hysteresis of the studied materials. Dimitrios G. Bekas and Alkiviadis S. Paipetis Copyright © 2015 Dimitrios G. Bekas and Alkiviadis S. Paipetis. All rights reserved. Energy Analysis of Contention Tree-Based Access Protocols in Dense Machine-to-Machine Area Networks Wed, 22 Apr 2015 14:05:16 +0000 http://www.hindawi.com/journals/js/2015/685164/ Machine-to-Machine (M2M) area networks aim at connecting an M2M gateway with a large number of energy-constrained devices that must operate autonomously for years. Therefore, attaining high energy efficiency is essential in the deployment of M2M networks. In this paper, we consider a dense M2M area network composed of hundreds or thousands of devices that periodically transmit data upon request from a gateway or coordinator. We theoretically analyse the devices’ energy consumption using two Medium Access Control (MAC) protocols which are based on a tree-splitting algorithm to resolve collisions among devices: the Contention Tree Algorithm (CTA) and the Distributed Queuing (DQ) access. We have carried out computer-based simulations to validate the accuracy of the theoretical models and to compare the energy performance using DQ, CTA, and Frame Slotted-ALOHA (FSA) in M2M area networks with devices in compliance with the IEEE 802.15.4 physical layer. Results show that the performance of DQ is totally independent of the number of contending devices, and it can reduce the energy consumed per device in more than 35% with respect to CTA and in more than 80% with respect to FSA. Francisco Vázquez-Gallego, Luis Alonso, and Jesus Alonso-Zarate Copyright © 2015 Francisco Vázquez-Gallego et al. All rights reserved. Lifetime Optimization of a Multiple Sink Wireless Sensor Network through Energy Balancing Sun, 19 Apr 2015 09:58:31 +0000 http://www.hindawi.com/journals/js/2015/921250/ The wireless sensor network consists of small limited energy sensors which are connected to one or more sinks. The maximum energy consumption takes place in communicating the data from the nodes to the sink. Multiple sink WSN has an edge over the single sink WSN where very less energy is utilized in sending the data to the sink, as the number of hops is reduced. If the energy consumed by a node is balanced between the other nodes, the lifetime of the network is considerably increased. The network lifetime optimization is achieved by restructuring the network by modifying the neighbor nodes of a sink. Only those nodes are connected to a sink which makes the total energy of the sink less than the threshold. This energy balancing through network restructuring optimizes the network lifetime. This paper depicts this fact through simulations done in MATLAB. Tapan Kumar Jain, Davinder Singh Saini, and Sunil Vidya Bhooshan Copyright © 2015 Tapan Kumar Jain et al. All rights reserved. Efficient Multiway Relaying for Data Sharing in Energy Harvesting Sensor Networks Wed, 15 Apr 2015 13:08:12 +0000 http://www.hindawi.com/journals/js/2015/285056/ In a wireless sensor network (WSN), sensors often need to share their measurements for applications like distributed estimation and detection or data aggregation. Here, we suggest using multiway relaying (MWR) for data sharing between energy harvesting sensors that cannot directly communicate with each other. We first start by studying the achievable data rate of amplify-and-forward (AF) MWR for energy harvesting sensors. Then, we show that, by backing off the transmit power at the sensors, not only better energy efficiency and longer lifetime are achieved, but also the data sharing rate increases. Based on this result, we further improve the performance of AF MWR in the assumed WSN by smartly adjusting the transmit power at the sensors. Our power allocation is devised in a way to improve the energy efficiency of MWR and increase the sum rate of data sharing between the sensors over the network lifetime. Simulation results are presented to verify the enhancement achieved by using our proposed power allocation technique. Moslem Noori and Masoud Ardakani Copyright © 2015 Moslem Noori and Masoud Ardakani. All rights reserved. Locomotion Strategy Selection for a Hybrid Mobile Robot Using Time of Flight Depth Sensor Wed, 15 Apr 2015 11:38:55 +0000 http://www.hindawi.com/journals/js/2015/425732/ The performance of a mobile robot can be improved by utilizing different locomotion modes in various terrain conditions. This creates the necessity of having a supervisory controller capable of recognizing different terrain types and changing the locomotion mode of the robot accordingly. This work focuses on the locomotion strategy selection problem for a hybrid legged wheeled mobile robot. Supervisory control of the robot is accomplished by the terrain recognizer, which classifies depth images obtained from a commercial time of flight depth sensor and selects different locomotion mode subcontrollers based on the recognized terrain type. For the terrain recognizer, a database is generated consisting of five terrain classes (Uneven, Level Ground, Stair Up, Stair Down, and Nontraversable). Depth images are enhanced using confidence map based filtering. The accuracy of the terrain classification using Support Vector Machine classifier for the testing database in five-class terrain recognition problem is 97%. Real-world experiments assess the locomotion abilities of the quadruped and the capability of the terrain recognizer in real-time settings. The results of these experiments show depth images processed in real time using machine learning algorithms can be used for the supervisory control of hybrid robots with legged and wheeled locomotion capabilities. Artur Saudabayev, Farabi Kungozhin, Damir Nurseitov, and Huseyin Atakan Varol Copyright © 2015 Artur Saudabayev et al. All rights reserved. Fabrication of Porous Silicon Based Humidity Sensing Elements on Paper Thu, 09 Apr 2015 07:34:07 +0000 http://www.hindawi.com/journals/js/2015/927396/ A roll-to-roll compatible fabrication process of porous silicon (pSi) based sensing elements for a real-time humidity monitoring is described. The sensing elements, consisting of printed interdigitated silver electrodes and a spray-coated pSi layer, were fabricated on a coated paper substrate by a two-step process. Capacitive and resistive responses of the sensing elements were examined under different concentrations of humidity. More than a three orders of magnitude reproducible decrease in resistance was measured when the relative humidity (RH) was increased from 0% to 90%. A relatively fast recovery without the need of any refreshing methods was observed with a change in RH. Humidity background signal and hysteresis arising from the paper substrate were dependent on the thickness of sensing pSi layer. Hysteresis in most optimal sensing element setup (a thick pSi layer) was still noticeable but not detrimental for the sensing. In addition to electrical characterization of sensing elements, thermal degradation and moisture adsorption properties of the paper substrate were examined in connection to the fabrication process of the silver electrodes and the moisture sensitivity of the paper. The results pave the way towards the development of low-cost humidity sensors which could be utilized, for example, in smart packaging applications or in smart cities to monitor the environment. Tero Jalkanen, Anni Määttänen, Ermei Mäkilä, Jaani Tuura, Martti Kaasalainen, Vesa-Pekka Lehto, Petri Ihalainen, Jouko Peltonen, and Jarno Salonen Copyright © 2015 Tero Jalkanen et al. All rights reserved. Optimization of an Accelerometer and Gyroscope-Based Fall Detection Algorithm Thu, 09 Apr 2015 06:40:33 +0000 http://www.hindawi.com/journals/js/2015/452078/ Falling is a common and significant cause of injury in elderly adults (>65 yrs old), often leading to disability and death. In the USA, one in three of the elderly suffers from fall injuries annually. This study’s purpose is to develop, optimize, and assess the efficacy of a falls detection algorithm based upon a wireless, wearable sensor system (WSS) comprised of a 3-axis accelerometer and gyroscope. For this study, the WSS is placed at the chest center to collect real-time motion data of various simulated daily activities (i.e., walking, running, stepping, and falling). Tests were conducted on 36 human subjects with a total of 702 different movements collected in a laboratory setting. Half of the dataset was used for development of the fall detection algorithm including investigations of critical sensor thresholds and the remaining dataset was used for assessment of algorithm sensitivity and specificity. Experimental results show that the algorithm detects falls compared to other daily movements with a sensitivity and specificity of 96.3% and 96.2%, respectively. The addition of gyroscope information enhances sensitivity dramatically from results in the literature as angular velocity changes provide further delineation of a fall event from other activities that may also experience high acceleration peaks. Quoc T. Huynh, Uyen D. Nguyen, Lucia B. Irazabal, Nazanin Ghassemian, and Binh Q. Tran Copyright © 2015 Quoc T. Huynh et al. All rights reserved. Simple Design of Wireless Sensor Networks for Traffic Jams Avoidance Wed, 08 Apr 2015 08:10:21 +0000 http://www.hindawi.com/journals/js/2015/380794/ Intelligent transportation systems (ITS) are usually approached by exhaustive measuring and complex signal processing including medium-high cost hardware deployment. In this paper, a novel design of a wireless sensor network system using magnetometers and microphones for the detection and avoidance of traffic jams is described and analyzed. The system, which can also be used for traffic monitoring and surveillance, is simple, energy efficient, and accurate which allows to be implemented with a reduced hardware cost. In order to reduce the maintenance tasks, mini solar panels would also be installed for powering up the motes in the near future. Víctor P. Gil Jiménez and M. Julia Fernández-Getino García Copyright © 2015 Víctor P. Gil Jiménez and M. Julia Fernández-Getino García. All rights reserved. Fabrication of a Needle Microsensor and Its Applications in the Detection of Dissolved Oxygen Tue, 07 Apr 2015 08:58:52 +0000 http://www.hindawi.com/journals/js/2015/408458/ A novel needle microsensor measurement system was fabricated and applied to determine the concentration of dissolved oxygen. Platinum nanoparticles were employed to modify the surface of copper-core electrode in order to improve electrochemical response signal. The homemade electrode displayed efficient electrocatalytic reduction activity towards dissolved oxygen. The sensor responded linearly to dissolved oxygen in the range of 10 μM to 0.195 mM and had a remarkable sensitivity of 9.02 μA/mM. In addition, it showed an excellent reproducibility, stability, and selectivity. These results indicated that the needle microsensor when used, could yield good performance. Moreover, it is believed to be a potential tool for studying specific substances at a cellular level or in vivo in future. Yuxin Fang, Di Zhang, Qing Xia, Shouhai Hong, Yuan Xu, and Yi Guo Copyright © 2015 Yuxin Fang et al. All rights reserved. A New MEMS Stochastic Model Order Reduction Method: Research and Application Sun, 05 Apr 2015 13:51:39 +0000 http://www.hindawi.com/journals/js/2015/125621/ Modeling and simulation of MEMS devices is a very complex tasks which involve the electrical, mechanical, fluidic, and thermal domains, and there are still some uncertainties that need to be accounted for during the robust design of MEMS actuators caused by uncertain material and/or geometric parameters. According to these problems, we put forward stochastic model order reduction method under random input conditions to facilitate fast time and frequency domain analyses; the method makes use of polynomial chaos expansions in terms of the random input variables for the matrices of a finite element model of the system and then uses its transformation matrix to reduce the model; the method is independent of the MOR algorithm, so it is seamlessly compatible with MOR method used in popular finite element solvers. The simulation results verify the method is effective in large scale MEMS design process. Bian Xiangjuan, Youping Gong, Chen Guojin, and Lv Yunpeng Copyright © 2015 Bian Xiangjuan et al. All rights reserved. Analyzing Multimode Wireless Sensor Networks Using the Network Calculus Tue, 31 Mar 2015 08:06:11 +0000 http://www.hindawi.com/journals/js/2015/851608/ The network calculus is a powerful tool to analyze the performance of wireless sensor networks. But the original network calculus can only model the single-mode wireless sensor network. In this paper, we combine the original network calculus with the multimode model to analyze the maximum delay bound of the flow of interest in the multimode wireless sensor network. There are two combined methods A-MM and N-MM. The method A-MM models the whole network as a multimode component, and the method N-MM models each node as a multimode component. We prove that the maximum delay bound computed by the method A-MM is tighter than or equal to that computed by the method N-MM. Experiments show that our proposed methods can significantly decrease the analytical delay bound comparing with the separate flow analysis method. For the large-scale wireless sensor network with 32 thousands of sensor nodes, our proposed methods can decrease about 70% of the analytical delay bound. Xi Jin, Nan Guan, Jintao Wang, and Peng Zeng Copyright © 2015 Xi Jin et al. All rights reserved. Architecture and Implementation of a Scalable Sensor Data Storage and Analysis System Using Cloud Computing and Big Data Technologies Mon, 30 Mar 2015 11:23:43 +0000 http://www.hindawi.com/journals/js/2015/834217/ Sensors are becoming ubiquitous. From almost any type of industrial applications to intelligent vehicles, smart city applications, and healthcare applications, we see a steady growth of the usage of various types of sensors. The rate of increase in the amount of data produced by these sensors is much more dramatic since sensors usually continuously produce data. It becomes crucial for these data to be stored for future reference and to be analyzed for finding valuable information, such as fault diagnosis information. In this paper we describe a scalable and distributed architecture for sensor data collection, storage, and analysis. The system uses several open source technologies and runs on a cluster of virtual servers. We use GPS sensors as data source and run machine-learning algorithms for data analysis. Galip Aydin, Ibrahim Riza Hallac, and Betul Karakus Copyright © 2015 Galip Aydin et al. All rights reserved. Gesture Recognition from Data Streams of Human Motion Sensor Using Accelerated PSO Swarm Search Feature Selection Algorithm Mon, 30 Mar 2015 09:21:07 +0000 http://www.hindawi.com/journals/js/2015/205707/ Human motion sensing technology gains tremendous popularity nowadays with practical applications such as video surveillance for security, hand signing, and smart-home and gaming. These applications capture human motions in real-time from video sensors, the data patterns are nonstationary and ever changing. While the hardware technology of such motion sensing devices as well as their data collection process become relatively mature, the computational challenge lies in the real-time analysis of these live feeds. In this paper we argue that traditional data mining methods run short of accurately analyzing the human activity patterns from the sensor data stream. The shortcoming is due to the algorithmic design which is not adaptive to the dynamic changes in the dynamic gesture motions. The successor of these algorithms which is known as data stream mining is evaluated versus traditional data mining, through a case of gesture recognition over motion data by using Microsoft Kinect sensors. Three different subjects were asked to read three comic strips and to tell the stories in front of the sensor. The data stream contains coordinates of articulation points and various positions of the parts of the human body corresponding to the actions that the user performs. In particular, a novel technique of feature selection using swarm search and accelerated PSO is proposed for enabling fast preprocessing for inducing an improved classification model in real-time. Superior result is shown in the experiment that runs on this empirical data stream. The contribution of this paper is on a comparative study between using traditional and data stream mining algorithms and incorporation of the novel improved feature selection technique with a scenario where different gesture patterns are to be recognized from streaming sensor data. Simon Fong, Justin Liang, Iztok Fister Jr., Iztok Fister, and Sabah Mohammed Copyright © 2015 Simon Fong et al. All rights reserved. Fibre Tip Sensor with Embedded FBG-LPG for Temperature and Refractive Index Determination by means of the Simple Measurement of the FBG Characteristics Thu, 26 Mar 2015 13:20:47 +0000 http://www.hindawi.com/journals/js/2015/491391/ A novel optical fibre sensing system based on a hybrid long period grating (LPG) and Bragg grating (FBG) configuration is proposed and demonstrated experimentally. The hybrid configuration, which uses the difference in temperature and refractive index (RI) different response of a Bragg grating and a long period grating, makes it possible to discriminate simultaneously the temperature and the refractive index of different aqueous solutions. RI (1.33 RIU–1.40 RIU) and temperature (21°C–28°C) working ranges have been experimentally determined. Experimental results show that the maximum accuracy in the refractive index measurement (0.004 RIU) with temperature compensation has been achieved within the working ranges. C. Berrettoni, C. Trono, V. Vignoli, and F. Baldini Copyright © 2015 C. Berrettoni et al. All rights reserved. Combination of Evidence with Different Weighting Factors: A Novel Probabilistic-Based Dissimilarity Measure Approach Thu, 26 Mar 2015 07:37:13 +0000 http://www.hindawi.com/journals/js/2015/509385/ To solve the invalidation problem of Dempster-Shafer theory of evidence (DS) with high conflict in multisensor data fusion, this paper presents a novel combination approach of conflict evidence with different weighting factors using a new probabilistic dissimilarity measure. Firstly, an improved probabilistic transformation function is proposed to map basic belief assignments (BBAs) to probabilities. Then, a new dissimilarity measure integrating fuzzy nearness and introduced correlation coefficient is proposed to characterize not only the difference between basic belief functions (BBAs) but also the divergence degree of the hypothesis that two BBAs support. Finally, the weighting factors used to reassign conflicts on BBAs are developed and Dempster’s rule is chosen to combine the discounted sources. Simple numerical examples are employed to demonstrate the merit of the proposed method. Through analysis and comparison of the results, the new combination approach can effectively solve the problem of conflict management with better convergence performance and robustness. Mengmeng Ma and Jiyao An Copyright © 2015 Mengmeng Ma and Jiyao An. All rights reserved. Modelling and Numerical Simulations of In-Air Reverberation Images for Fault Detection in Medical Ultrasonic Transducers: A Feasibility Study Wed, 25 Mar 2015 10:06:33 +0000 http://www.hindawi.com/journals/js/2015/796439/ A simplified two-dimensional finite element model which simulates the in-air reverberation image produced by medical ultrasonic transducers has been developed. The model simulates a linear array consisting of 128 PZT-5A crystals, a tungsten-epoxy backing layer, an Araldite matching layer, and a Perspex lens layer. The thickness of the crystal layer is chosen to simulate pulses centered at 4 MHz. The model is used to investigate whether changes in the electromechanical properties of the individual transducer layers (backing layer, crystal layer, matching layer, and lens layer) have an effect on the simulated in-air reverberation image generated. Changes in the electromechanical properties are designed to simulate typical medical transducer faults such as crystal drop-out, lens delamination, and deterioration in piezoelectric efficiency. The simulations demonstrate that fault-related changes in transducer behaviour can be observed in the simulated in-air reverberation image pattern. This exploratory approach may help to provide insight into deterioration in transducer performance and help with early detection of faults. W. Kochański, M. Boeff, Z. Hashemiyan, W. J. Staszewski, and P. K. Verma Copyright © 2015 W. Kochański et al. All rights reserved. A Survey on Spectrum Utilization in Wireless Sensor Networks Mon, 23 Mar 2015 11:17:10 +0000 http://www.hindawi.com/journals/js/2015/624610/ In recent years, the industrial, scientific, and medical (ISM) bands have been intensively shared with unlicensed wireless communications applications such as wireless sensor networks (WSNs). With flourishing popularity of sensor devices and increasing installation of wireless sensor nodes, the cross technology interference (CTI) has become a considerable real-world problem. Because of CTI, wireless devices suffer significant communication dilemma. Moreover, ISM band, as the main communication medium of WSN, should be reasonably utilized in an efficient and effective manner. Extensive approaches have been proposed to explore spectrum utilization in WSN. However, there is no such one, which systematically organizes these works. In this paper, we present a comprehensive survey on spectrum utilization in WSNs. To achieve this goal, We first illustrate the background of WSN and spectrum utilization. Our concern on CTI is then noted. Later we demonstrate the importance of efficient spectrum utilization. Eventually, through classification and summary of recent related works, we provide an essential structure of research in titled field and detailed intellectual merits of published works. Our survey covers more than 80 studies in the scope of spectrum utilization in WSN. Hongyao Luo, Zhichuan Huang, and Ting Zhu Copyright © 2015 Hongyao Luo et al. All rights reserved. Differentiation of Eight Commercial Mushrooms by Electronic Nose and Gas Chromatography-Mass Spectrometry Thu, 19 Mar 2015 09:13:38 +0000 http://www.hindawi.com/journals/js/2015/374013/ Volatile profiles of eight mushrooms were characterized by gas chromatography-mass spectrometry and electronic nose analysis. Volatile compounds including 11 alcohols, 11 ketones, 15 aldehydes, 3 sulfur compounds and alkenes, 8 terpenes, 7 acid and esters, 5 heterocyclic compounds, 20 aromatic compounds, and 4 other compounds were identified. The overall aroma properties of the mushrooms were analyzed by the electronic nose. Results indicated that the e-nose sensors have the ability to accurately respond to different mushrooms with similar fingerprint chromatograms. The relationship between the GC-MS data and e-nose responses of different mushrooms was modeled by principal component analysis and partial least squares regression. This combination for the volatile analysis with chemometric methods can be applied to distinguish different mushrooms successfully. Furthermore, it is concluded that the volatile composition of commercial mushrooms could benefit a finger spectrum by e-nose to identify the species of edible fungi. Jinjie Zhou, Tao Feng, and Ran Ye Copyright © 2015 Jinjie Zhou et al. All rights reserved. Internet of Vehicles for E-Health Applications in View of EMI on Medical Sensors Tue, 17 Mar 2015 07:37:16 +0000 http://www.hindawi.com/journals/js/2015/315948/ Wireless technologies are pervasive to support ubiquitous healthcare applications. However, RF transmission in wireless technologies can lead to electromagnetic interference (EMI) on medical sensors under a healthcare scenario, and a high level of EMI may lead to a critical malfunction of medical sensors. In view of EMI to medical sensors, we propose a joint power and rate control algorithm under game theoretic framework to schedule data transmission at each of wireless sensors. The objective of such a game is to maximize the utility of each wireless user subject to the EMI constraints for medical sensors. We show that the proposed game has a unique Nash equilibrium and our joint power and rate control algorithm would converge to the Nash equilibrium. Numerical results illustrate that the proposed algorithm can achieve robust performance against the variations of mobile hospital environments. Di Lin, Xuanli Wu, Fabrice Labeau, and Athanasios Vasilakos Copyright © 2015 Di Lin et al. All rights reserved. Toxicity Biosensor for Sodium Dodecyl Sulfate Using Immobilized Green Fluorescent Protein Expressing Escherichia coli Tue, 17 Mar 2015 07:21:39 +0000 http://www.hindawi.com/journals/js/2015/809065/ Green fluorescent protein (GFP) is suitable as a toxicity sensor due to its ability to work alone without cofactors or substrates. Its reaction with toxicants can be determined with fluorometric approaches. GFP mutant gene (C48S/S147C/Q204C/S65T/Q80R) is used because it has higher sensitivity compared to others GFP variants. A novel sodium dodecyl sulfate (SDS) toxicity detection biosensor was built by immobilizing GFP expressing Escherichia coli in k-Carrageenan matrix. Cytotoxicity effect took place in the toxicity biosensor which leads to the decrease in the fluorescence intensity. The fabricated E. coli GFP toxicity biosensor has a wide dynamic range of 4–100 ppm, with LOD of 1.7 ppm. Besides, it possesses short response time (<1 min), high reproducibility (0.76% RSD) and repeatability (0.72% RSD, ), and long-term stability (46 days). E. coli GFP toxicity biosensor has been applied to detect toxicity induced by SDS in tap water, river water, and drinking water. High recovery levels of SDS indicated the applicability of E. coli GFP toxicity biosensor in real water samples toxicity evaluation. Lia Ooi, Lee Yook Heng, and Asmat Ahmad Copyright © 2015 Lia Ooi et al. All rights reserved. A Bilinear Pairing-Based Dynamic Key Management and Authentication for Wireless Sensor Networks Sun, 15 Mar 2015 08:12:40 +0000 http://www.hindawi.com/journals/js/2015/534657/ In recent years, wireless sensor networks have been used in a variety of environments; a wireless network infrastructure, established to communicate and exchange information in a monitoring area, has also been applied in different environments. However, for sensitive applications, security is the paramount issue. In this paper, we propose using bilinear pairing to design dynamic key management and authentication scheme of the hierarchical sensor network. We use the dynamic key management and the pairing-based cryptography (PBC) to establish the session key and the hash message authentication code (HMAC) to support the mutual authentication between the sensors and the base station. In addition, we also embed the capability of the Global Positioning System (GPS) to cluster nodes to find the best path of the sensor network. The proposed scheme can also provide the requisite security of the dynamic key management, mutual authentication, and session key protection. Our scheme can defend against impersonation attack, replay attack, wormhole attack, and message manipulation attack. Chin-Ling Chen, Tzay-Farn Shih, Yu-Ting Tsai, and De-Kui Li Copyright © 2015 Chin-Ling Chen et al. All rights reserved. A System of Driving Fatigue Detection Based on Machine Vision and Its Application on Smart Device Sun, 15 Mar 2015 07:15:51 +0000 http://www.hindawi.com/journals/js/2015/548602/ Driving fatigue is one of the most important factors in traffic accidents. In this paper, we proposed an improved strategy and practical system to detect driving fatigue based on machine vision and Adaboost algorithm. Kinds of face and eye classifiers are well trained by Adaboost algorithm in advance. The proposed strategy firstly detects face efficiently by classifiers of front face and deflected face. Then, candidate region of eye is determined according to geometric distribution of facial organs. Finally, trained classifiers of open eyes and closed eyes are used to detect eyes in the candidate region quickly and accurately. The indexes which consist of PERCLOS and duration of closed-state are extracted in video frames real time. Moreover, the system is transplanted into smart device, that is, smartphone or tablet, due to its own camera and powerful calculation performance. Practical tests demonstrated that the proposed system can detect driver fatigue with real time and high accuracy. As the system has been planted into portable smart device, it could be widely used for driving fatigue detection in daily life. Wanzeng Kong, Lingxiao Zhou, Yizhi Wang, Jianhai Zhang, Jianhui Liu, and Shenyong Gao Copyright © 2015 Wanzeng Kong et al. All rights reserved.