Journal of Sensors http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. A Trusted Real-Time Scheduling Model for Wireless Sensor Networks Wed, 03 Feb 2016 11:43:12 +0000 http://www.hindawi.com/journals/js/2016/8958170/ Heterogeneous multicore and multiprocessor systems have been widely used for wireless sensor information processing, but system energy consumption has become an increasingly important issue. To ensure the reliable and safe operation of sensor systems, the task scheduling success rate of heterogeneous platforms should be improved, and energy consumption should be reduced. This work establishes a trusted task scheduling model for wireless sensor networks, proposes an energy consumption model, and adopts the ant colony algorithm and bee colony algorithm for the task scheduling of a real-time sensor node. Experimental result shows that the genetic algorithm and ant colony algorithm can efficiently solve the energy consumption problem in the trusted task scheduling of a wireless sensor and that the performance of the bee colony algorithm is slightly inferior to that of the first two methods. Weizhe Zhang, Boyu Song, and Enci Bai Copyright © 2016 Weizhe Zhang et al. All rights reserved. Biosensors Used for Quantification of Nitrates in Plants Wed, 03 Feb 2016 11:38:04 +0000 http://www.hindawi.com/journals/js/2016/1630695/ Nitrogen is essential for the plant because it is used for the production of chlorophyll, proteins, nucleic acids, amino acids, and other cellular compounds; nitrogen is available in two forms: ammonium and nitrate. Several tools have been used to quantify nitrates in plants such as the Kjeldahl method and Dumas combustion digestion; however, they are destructive and long time-consuming methods. To solve these disadvantages, methods such as selective electrodes, optical sensors, reflectometers, and images based sensors have been developed; nonetheless, all these techniques show interference when carrying out measurements. Currently, biosensors based on genetic constructions, based on the response of promoter gene fused to Gene Fluorescent Protein (GFP), are gaining popularity, because they improve the accuracy of measurements of nitrate by avoiding the interference of carriers ion, high salt conditions, and other factors. The present review shows the different methods to quantify the nitrogen in plants; later, a biosensors perspective is presented, mainly focused on biosensors based on organism genetically modified. The review presents a list of promoter and reporter genes that could be used to develop different kind of sensors, and a perspective of sensors to measure quantitatively the nitrogen is presented. Romero-Galindo Raul, Torres-Pacheco Irineo, Guevara-Gonzalez Ramon Gerardo, and Contreras-Medina Luis Miguel Copyright © 2016 Romero-Galindo Raul et al. All rights reserved. Human Breathing Rate Estimation from Radar Returns Using Harmonically Related Filters Wed, 03 Feb 2016 06:17:50 +0000 http://www.hindawi.com/journals/js/2016/9891852/ Radar-based noncontact sensing of life sign signals is often used in safety and rescue missions during disasters such as earthquakes and avalanches and for home care applications. The radar returns obtained from a human target contain the breathing frequency along with its strong higher harmonics depending on the target’s posture. As a consequence, well understood, computationally efficient, and the most popular traditional FFT-based estimators that rely only on the strongest peak for estimates of breathing rates may be inaccurate. The paper proposes a solution for correcting the estimation errors of such single peak-based algorithms. The proposed method is based on using harmonically related comb filters over a set of all possible breathing frequencies. The method is tested on three subjects for different postures, for different distances between the radar and the subject, and for two different radar platforms: PN-UWB and phase modulated-CW (PM-CW) radars. Simplified algorithms more suitable for real-time implementation have also been proposed and compared using accuracy and computational complexity. The proposed breathing rate estimation algorithms provide a reduction of about 81% and 80% in the mean absolute error of breathing rates in comparison to the traditional FFT-based methods using strongest peak detection, for PN-UWB and PM-CW radars, respectively. Mohamed Mabrouk, Sreeraman Rajan, Miodrag Bolic, Mohamad Forouzanfar, Hilmi R. Dajani, and Izmail Batkin Copyright © 2016 Mohamed Mabrouk et al. All rights reserved. Spectrum-Aware Geographic Routing in Cognitive Vehicular Ad Hoc Network Using a Kalman Filter Tue, 02 Feb 2016 12:05:15 +0000 http://www.hindawi.com/journals/js/2016/8572601/ We propose a position-based routing protocol for cognitive radio vehicular ad hoc networks (CR-VANETs) using a Kalman filter algorithm. The protocol first selects an idle channel from among all the channels available to a vehicle while moving on a straight road and then finds the best relay node to deliver the packet to the destination. The selection of a relay node is done by dividing the vehicular transmission range into five regions, and then the source/relay node selects the one that is in the region having a higher preference than other regions. Communication between two vehicles occurs only when both the vehicles are on the same channel. Delay may increase while sensing the channel and selecting the relay node. To reduce the delay, we use a Kalman filter to predict the future positions of all moving vehicles in the network. We consider vehicle-to-vehicle communication and compare our protocol for different probabilities of primary user being idle. Our proposed protocol shows improvement in both packet delivery ratio and end-to-end delay. Huma Ghafoor and Insoo Koo Copyright © 2016 Huma Ghafoor and Insoo Koo. All rights reserved. Autonomous WiFi Sensor for Heating Systems in the Internet of Things Tue, 02 Feb 2016 06:20:01 +0000 http://www.hindawi.com/journals/js/2016/7235984/ In smart cities and home applications, the use of Wireless Sensor Networks to extract environmental data becomes more common with the passing of time. These sensors are used for a wide array of applications, but mainly to manage energy consumption in domestic buildings. One of the key energy consumers in households is heating systems. To monitor them, sensors are used with wireless communication protocols, like ZigBee, to transmit data to a central processing unit (CPU). WiFi communications, on the contrary, are rarely seen in these implementations due to its high energy consumption, although almost in every home one can find such networks. Yet, with the Internet of Things (IoT), new revisions of the standard have arisen which enable this technology for wireless sensing. To validate this theory and fill a technological necessity, this proposal is presented. In this work, the design and implementation of an autonomous WiFi sensor, paired with thermoelectric energy harvesting, are presented as an IoT solution for monitoring heating devices. For this, a thorough analysis of the proposed architecture is presented. Tests regarding energy consumption and generation, efficiency, and real world scenario trials are done. Finalizing, a comparison between the obtained results and current implementations is shown. C. A. Trasviña-Moreno, R. Blasco, R. Casas, and A. Marco Copyright © 2016 C. A. Trasviña-Moreno et al. All rights reserved. Determining the Optimal Placement of Sensors on a Concrete Arch Dam Using a Quantum Genetic Algorithm Mon, 01 Feb 2016 07:22:43 +0000 http://www.hindawi.com/journals/js/2016/2567305/ Structural modal identification has become increasingly important in health monitoring, fault diagnosis, vibration control, and dynamic analysis of engineering structures in recent years. Based on an analysis of traditional optimization algorithms, this paper proposes a novel sensor optimization criterion that combines the effective independence (EFI) method with the modal strain energy (MSE) method. Considering the complex structure and enormous degrees of freedom (DOFs) of modern concrete arch dam, a quantum genetic algorithm (QGA) is used to optimize the corresponding sensor network on the upstream surface of a dam. Finally, this study uses a specific concrete arch dam as an example and determines the optimal sensor placement using the proposed method. By comparing the results with the traditional optimization methods, the proposed method is shown to maximize the spatial intersection angle among the modal vectors of sensor network and can effectively resist ambient perturbations, which will make the identified modal parameters more precise. Kai Zhu, Chongshi Gu, Jianchun Qiu, Wanxin Liu, Chunhui Fang, and Bo Li Copyright © 2016 Kai Zhu et al. All rights reserved. Adaptive Window Size-Based Medium Access Control Protocol for Cognitive Radio Wireless Sensor Networks Wed, 27 Jan 2016 13:32:49 +0000 http://www.hindawi.com/journals/js/2016/2049859/ Many existing medium access control protocols for cognitive radio wireless sensor networks waste bandwidth and suffer from delay because of the fixed channel negotiation period in the common control channel. In this paper, we propose a medium access control protocol for cognitive radio wireless sensor networks that adjusts the channel negotiation period based on network density. We simulate the proposed approach and compare it to the performance of the fixed channel negotiation period based approaches. The results show that the proposed approach efficiently utilizes white spaces and increases the aggregated goodput. Gyanendra Prasad Joshi, Seung Yeob Nam, Sung Won Kim, and Byung-Seo Kim Copyright © 2016 Gyanendra Prasad Joshi et al. All rights reserved. Wide Range Fiber Displacement Sensor Based on Bending Loss Wed, 27 Jan 2016 12:04:13 +0000 http://www.hindawi.com/journals/js/2016/4201870/ A wide range fiber optic sensor system for displacement and crack monitoring is developed. In the proposed fiber optic sensor system, a number of fiber loops are formed from a single fiber and each fiber loop is used as a crack or displacement sensor. The feasibility and the dynamic range of the fiber sensor developed in this manner are investigated experimentally. Both glass fibers and plastic fibers are used in the experiments. Experimental results show that the new fiber optic sensor has a wide range (maximum range is 88 mm) and this sensor also has a high sensitivity for displacement and crack monitoring when an appropriate diameter of the fiber loop is selected as the sensor. Moreover, the proposed method is very simple and has low cost, so in situ application potential of the proposed sensor is high. Jinlei Zhao, Tengfei Bao, and Tribikram Kundu Copyright © 2016 Jinlei Zhao et al. All rights reserved. Arc-Induced Long Period Fiber Gratings Wed, 27 Jan 2016 07:26:56 +0000 http://www.hindawi.com/journals/js/2016/3598634/ Long period fiber gratings produced by the electric arc technique have found an increasing interest by the scientific community due to their ease to fabricate, virtually enabling the inscription in any kind of fiber, low cost, and flexibility. In 2005 we have presented the first review on this subject. Since then, important achievements have been reached such as the identification of the mechanisms responsible for gratings formation, the type of symmetry, the conditions to increase fabrication reproducibility, and their inscription in the turning points with grating periods below 200 μm. Several interesting applications in the sensing area, including those sensors working in reflection, have been demonstrated and others are expected, namely, related to the monitoring of extreme temperatures, cryogenic and high temperatures, and high sensitivity refractometric sensors resulting from combining arc-induced gratings in the turning points and the deposition of thin films in the transition region. Therefore, due to its pertinence, in this paper we review the main achievements obtained concerning arc-induced long period fiber gratings, with special focus on the past ten years. Gaspar Rego Copyright © 2016 Gaspar Rego. All rights reserved. Time and Frequency Localized Pulse Shape for Resolution Enhancement in STFT-BOTDR Wed, 27 Jan 2016 07:01:57 +0000 http://www.hindawi.com/journals/js/2016/3204130/ Short-Time Fourier Transform-Brillouin Optical Time-Domain Reflectometry (STFT-BOTDR) implements STFT over the full frequency spectrum to measure the distributed temperature and strain along the optic fiber, providing new research advances in dynamic distributed sensing. The spatial and frequency resolution of the dynamic sensing are limited by the Signal to Noise Ratio (SNR) and the Time-Frequency (T-F) localization of the input pulse shape. T-F localization is fundamentally important for the communication system, which suppresses interchannel interference (ICI) and intersymbol interference (ISI) to improve the transmission quality in multicarrier modulation (MCM). This paper demonstrates that the T-F localized input pulse shape can enhance the SNR and the spatial and frequency resolution in STFT-BOTDR. Simulation and experiments of T-F localized different pulses shapes are conducted to compare the limitation of the system resolution. The result indicates that rectangular pulse should be selected to optimize the spatial resolution and Lorentzian pulse could be chosen to optimize the frequency resolution, while Gaussian shape pulse can be used in general applications for its balanced performance in both spatial and frequency resolution. Meanwhile, T-F localization is proved to be useful in the pulse shape selection for system resolution optimization. Linqing Luo, Bo Li, Yifei Yu, Xiaomin Xu, Kenichi Soga, and Jize Yan Copyright © 2016 Linqing Luo et al. All rights reserved. Review of the Strain Modulation Methods Used in Fiber Bragg Grating Sensors Tue, 26 Jan 2016 13:44:29 +0000 http://www.hindawi.com/journals/js/2016/1284520/ Fiber Bragg grating (FBG) is inherently sensitive to temperature and strain. By modulating FBG’s strain, various FBG sensors have been developed, such as sensors with enhanced or reduced temperature sensitivity, strain/displacement sensors, inclinometers, accelerometers, pressure meters, and magnetic field meters. This paper reviews the strain modulation methods used in these FBG sensors and categorizes them according to whether the strain of an FBG is changed evenly. Then, those even-strain-change methods are subcategorized into (1) attaching/embedding an FBG throughout to a base and (2) fixing the two ends of an FBG and (2.1) changing the distance between the two ends or (2.2) bending the FBG by applying a transverse force at the middle of the FBG. This review shows that the methods of “fixing the two ends” are prominent because of the advantages of large tunability and frequency modulation. Kuo Li Copyright © 2016 Kuo Li. All rights reserved. Novel Aerial 3D Mapping System Based on UAV Platforms and 2D Laser Scanners Tue, 26 Jan 2016 13:01:58 +0000 http://www.hindawi.com/journals/js/2016/4158370/ The acquisition of 3D geometric data from an aerial view implies a high number of advantages with respect to terrestrial acquisition, the greatest being that aerial view allows the acquisition of information from areas with no or difficult accessibility, such as roofs and tops of trees. If the aerial platform is copter-type, other advantages are present, such as the capability of displacement at very low-speed, allowing for a more detailed acquisition. This paper presents a novel Aerial 3D Mapping System based on a copter-type platform, where a 2D laser scanner is integrated with a GNSS sensor and an IMU for the generation of georeferenced 3D point clouds. The accuracy and precision of the system are evaluated through the measurement of geometries in the point clouds generated by the system, as well as through the geolocation of target points for which the real global coordinates are known. David Roca, Joaquín Martínez-Sánchez, Susana Lagüela, and Pedro Arias Copyright © 2016 David Roca et al. All rights reserved. Measuring Gas Concentration and Wind Intensity in a Turbulent Wind Tunnel with a Mobile Robot Sun, 24 Jan 2016 09:22:36 +0000 http://www.hindawi.com/journals/js/2016/7184980/ This paper presents the measurement of gas concentration and wind intensity performed with a mobile robot in a custom turbulent wind tunnel designed for experimentation with customizable wind and gas leak sources. This paper presents the representation in different information layers of the measurements obtained in the turbulent wind tunnel under different controlled environmental conditions in order to describe the plume of the gas and wind intensities inside the experimentation chamber. The information layers have been generated from the measurements gathered by individual onboard gas and wind sensors carried out by an autonomous mobile robot. On the one hand, the assumption was that the size and cost of these specialized sensors do not allow the creation of a net of sensors or other measurement alternatives based on the simultaneous use of several sensors, and on the other hand, the assumption is that the information layers created will have application on the development and test of automatic gas source location procedures based on reactive or nonreactive algorithms. Dani Martínez, Javier Moreno, Marcel Tresanchez, Eduard Clotet, Juan Manuel Jiménez-Soto, Rudys Magrans, Antonio Pardo, Santiago Marco, and Jordi Palacín Copyright © 2016 Dani Martínez et al. All rights reserved. A Comparison of Tactile Sensors for In-Hand Object Location Thu, 21 Jan 2016 14:24:49 +0000 http://www.hindawi.com/journals/js/2016/2943610/ This work presents an extensive analysis of the usefulness of tactile sensors for in-hand object localization. Our analysis is based on a previous work where we proposed a method for the evaluation of tactile data using two algorithms: a Particle Filter algorithm and an Iterative Closest Point algorithm. In particular, we present a comparison of six different sensors, including two pairs of sensors based on similar technology, showing how the design and distribution of tactile sensors can affect the performance. Also, together with previous results where we demonstrated the importance of the synergy between tactile data and hand geometry, we corroborate that it is possible to obtain more similar performance with a simple fingertip sensor, than with more complex and expensive tactile sensors. Raul Fernandez, Andres S. Vazquez, Ismael Payo, and Antonio Adan Copyright © 2016 Raul Fernandez et al. All rights reserved. An Improved GPSR Algorithm Based on Energy Gradient and APIT Grid Mon, 18 Jan 2016 16:32:56 +0000 http://www.hindawi.com/journals/js/2016/2519714/ We investigate GPSR algorithms of WSN and propose an improved routing algorithm based on energy gradient and APIT grid to solve the problem of high and unbalanced energy consumption of GPSR. In GPSR, network uses greedy algorithm and right-hand rule to establish routing paths, and the path keeps running till some nodes within the path are invalid because energy is exhausted, which would lead to the high energy consumption of some nodes in the path and the low energy consumption of others nearby the nodes not in the path as well as bringing high and unbalanced energy consumption of the network. Regarding these problems, we use APIT localization algorithm and APIT grid to query and establish routing paths and establish the corresponding energy gradient when messages are transmitted along the routing paths. When some nodes are approaching the threshold status, we use right-hand rule and recursion greedy algorithm in advance to plan a new routing path towards the target area. When query messages arrive at the event area, the network uses a different method to transmit data according to the density of sensor nodes. Simulation experiments show that the improved routing algorithm is capable of reducing the energy consumption of network and extending the lifecycle of network. Zhuang Liu, Xin Feng, Jingjing Zhang, Teng Li, and Yanlong Wang Copyright © 2016 Zhuang Liu et al. All rights reserved. A Simple and Facile Glucose Biosensor Based on Prussian Blue Modified Graphite String Mon, 18 Jan 2016 16:28:52 +0000 http://www.hindawi.com/journals/js/2016/1859292/ This work describes the string sensor for the simple and sensitive detection of glucose which is based on Prussian blue (PB) modified graphite utilizing dipping. First, PB modified graphite (PB-G) strings are characterized by physical and electrochemical techniques to optimize the PB-G layer thickness. Then, glucose oxidase (GOx) is immobilized on PB-G string electrode with biocompatible chitosan overlayer (Chi/GOx/PB-G). The Chi/GOx/PB-G string electrode exhibits a sensitivity of 641.3 μA·mM−1·cm−2 to glucose with a linear range of 0.03 to 1.0 mM () and a rapid response time (<3 s). Moreover, the Chi/GOx/PB-G string electrodes are less sensitive to common interference materials such as ascorbic acid, uric acid, galactose, and acetaminophen than to glucose. The Chi/GOx/PB-G string electrodes also show excellent reproducibility (<5% RSD). Therefore, our Chi/GOx/PB-G string electrodes can be simple, robust, and reliable tools for glucose sensing which can avoid complicated and difficult multistep fabrication processes. In addition, we expect that they have many potential applications in fields ranging from health care to food analysis, in particular where single use is favorable. Seung Ho Lee, Joo-Ho Chung, Hun-Kuk Park, and Gi-Ja Lee Copyright © 2016 Seung Ho Lee et al. All rights reserved. A New Small Drifter for Shallow Water Basins: Application to the Study of Surface Currents in the Muggia Bay (Italy) Thu, 14 Jan 2016 11:56:33 +0000 http://www.hindawi.com/journals/js/2016/6589636/ A new small drifter prototype for measuring current immediately below the free surface in a water basin is proposed in this paper. The drifter dimensions make it useful for shallow water applications. The drifter transmits its GPS location via GSM phone network. The drifter was used to study the trajectory of the surface current in the Muggia bay, the latter containing the industrial harbor of the city of Trieste (Italy). The analysis has been carried out under a wide variety of wind conditions. As regards the behavior of the drifter, the analysis has shown that it is well suited to detect the water current since its motion is marginally affected by the wind. The study has allowed detecting the main features of the surface circulation within the Muggia bay under different meteorological conditions. Also, the study has shown that the trajectory of the surface current within the bay is weakly affected by the Coriolis force. Carmelo Nasello and Vincenzo Armenio Copyright © 2016 Carmelo Nasello and Vincenzo Armenio. All rights reserved. A Dual-Band Antenna for RF Energy Harvesting Systems in Wireless Sensor Networks Thu, 14 Jan 2016 08:22:32 +0000 http://www.hindawi.com/journals/js/2016/5725836/ In this paper, we focus on ambient radio frequency energy available from commercial broadcasting stations in order to provide a system based on RF energy harvesting using a new design of receiving antenna. Several antenna designs have been proposed for use in RF energy harvesting systems, as a pertinent receiving antenna design is highly required since the antenna features can affect the amount of energy harvested. The proposed antenna is aimed at greatly increasing the energy harvesting efficiency over Wi-Fi bands: 2.45 GHz and 5 GHz. This provides a promising alternative energy source in order to power sensors located in harsh environments or remote places, where other energy sources are impracticable. The dual-band antenna can be easily integrated with RF energy harvesting system on the same circuit board. Simulations and measurements were carried out to evaluate the antenna performances and investigate the effects of different design parameters on the antenna performance. The receiving antenna meets the required bandwidth specification and provides peak gain of more than 4 dBi across the operating band. A. Bakkali, J. Pelegri-Sebastia, T. Sogorb, V. Llario, and A. Bou-Escriva Copyright © 2016 A. Bakkali et al. All rights reserved. Temperature Dependence of Sensors Based on Silver-Decorated Nitrogen-Doped Multiwalled Carbon Nanotubes Wed, 13 Jan 2016 10:01:03 +0000 http://www.hindawi.com/journals/js/2016/4319498/ Vapor sensors are easily fabricated onto alumina substrates using foils of silver-decorated nitrogen-doped multiwalled carbon nanotubes (CNX-MWNTs-Ag) as active sensing material. The vapor sensors are tested using carbon disulfide, acetone, ethanol, and chloroform vapors. The CNX-MWNTs are produced by chemical vapor deposition process and then decorated with 14 nm Ag nanoparticles (Ag-NPs). The samples are characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Our results demonstrate that Ag-decorated CNX-MWNTs exhibit a better response and sensitivity when compared with pristine CNX-MWNTs based sensors, making them promising candidates for air-pollutants environmental monitoring. The temperature effect on the sensor performance is also studied; we found that the detection mechanism could be tuned from physisorption, at room temperature, to chemisorption at higher working temperature. Finally, first-principles density functional calculations are carried out to understand the interactions between the systems involved in the sensors, finding good agreement between experimental results and the theoretical approach. Eduardo Gracia-Espino, Bernabé Rebollo-Plata, Hugo Martínez-Gutiérrez, Emilio Muñoz-Sandoval, Florentino López-Urías, Morinobu Endo, Humberto Terrones, and Mauricio Terrones Copyright © 2016 Eduardo Gracia-Espino et al. All rights reserved. Brillouin Optical Time Domain Analysis Sensor for Active Vibration Control of a Cantilever Beam Tue, 12 Jan 2016 11:36:25 +0000 http://www.hindawi.com/journals/js/2016/1351378/ The paper reports the use of a distributed optical fiber sensor based on stimulated Brillouin scattering, for structural vibration control. A cantilevered flexible aluminum beam was used as test-bed for vibration control. The proposed approach allows acquiring simultaneously the dynamic strain at several locations. The dynamic strain measured at one (or more) fiber location can be used to implement any vibration control algorithm. Experimental results are reported in which a voice coil, positioned near the fixed end of the cantilever beam, was employed as actuator for the reduction of the vibrations related to the first bending mode of the beam. Aldo Minardo, Agnese Coscetta, Salvatore Pirozzi, and Luigi Zeni Copyright © 2016 Aldo Minardo et al. All rights reserved. An Open and Modular Hardware Node for Wireless Sensor and Body Area Networks Sun, 10 Jan 2016 11:21:03 +0000 http://www.hindawi.com/journals/js/2016/2978073/ Health monitoring is nowadays one of the hottest markets due to the increasing interest in prevention and treatment of physical problems. In this context the development of wearable, wireless, open-source, and nonintrusive sensing solutions is still an open problem. Indeed, most of the existing commercial architectures are closed and provide little flexibility. In this paper, an open hardware architecture for designing a modular wireless sensor node for health monitoring is proposed. By separating the connection and sensing functions in two separate boards, compliant with the IEEE1451 standard, we add plug and play capabilities to analog transducers, while granting at the same time a high level of customization. As an additional contribution of the work, we developed a cosimulation tool which simplifies the physical connection with the hardware devices and provides support for complex systems. Finally, a wireless body area network for fall detection and health monitoring, based on wireless node prototypes realized according to the proposed architecture, is presented as an application scenario. L. Ciabattoni, A. Freddi, S. Longhi, A. Monteriù, L. Pepa, and M. Prist Copyright © 2016 L. Ciabattoni et al. All rights reserved. GSR-TDMA: A Geometric Spatial Reuse-Time Division Multiple Access MAC Protocol for Multihop Underwater Acoustic Sensor Networks Sun, 10 Jan 2016 10:01:30 +0000 http://www.hindawi.com/journals/js/2016/6024610/ The nonnegligible propagation delay of acoustic signals causes spatiotemporal uncertainty that occasionally enables simultaneous, collision-free packet transmission among underwater nodes (UNs). These transmissions can be handled by efficiently managing the channel access of the UNs in the data-link layer. To this end, Geometric Spatial Reuse-TDMA (GSR-TDMA), a new TDMA-based MAC protocol, is designed for use in centralized, multihop underwater acoustic sensor networks (UASNs), and in this case all UNs are periodically scheduled after determining a geometric map according to the information on their location. The scheduling strategy increases the number of UNs that send packets coincidentally via two subscheduling configurations (i.e., interhop and intrahop scheduling). Extensive simulations are used to investigate the reception success rate (RSR) and the multihop delay (MHD) of GSR-TDMA, and the results are compared to those of previous approaches, including C-MAC and HSR-TDMA. GSR-TDMA outperforms C-MAC; the RSR of GSR-TDMA is 15% higher than that of C-MAC, and the MHD of GSR-TDMA is 30% lower than that of C-MAC at the most. In addition, GSR-TDMA provides even better performance improvements over HSR-TDMA; the RSR of GSR-TDMA is 50% higher than that of HSR-TDMA, and the MHD of GSR-TDMA is an order of lower than that of HSR-TDMA at the most. Changho Yun and Yong-Kon Lim Copyright © 2016 Changho Yun and Yong-Kon Lim. All rights reserved. Delay, Reliability, and Throughput Based QoS Profile: A MAC Layer Performance Optimization Mechanism for Biomedical Applications in Wireless Body Area Sensor Networks Wed, 06 Jan 2016 13:32:59 +0000 http://www.hindawi.com/journals/js/2016/7170943/ Recently, increasing demand for remote healthcare monitoring systems poses a specific set of Quality of Services (QoS) requirements to the MAC layer protocols and standards (IEEE 802.15.6, IEEE 802.15.4, etc.) of Wireless Body Area Sensor Networks (WBASNs). They mainly include time bounded services (latency), reliable data transmission, fair channel distribution, and specified data rates. The existing MAC protocols of WBASNs are lack of a specific set of QoS. To address this, the paper proposes a QoS profile named delay, reliability, and throughput (DRT). The QoS values computed through DRT profile provide maximum reliability of data transmission within an acceptable latency and data rates. The DRT is based on the carrier sense multiple access with collision avoidance (CSMA/CA) channel access mechanism and considers IEEE 802.15.4 (low-rate WPAN) and IEEE 802.15.6 (WBASN). Further, a detailed performance analysis of different frequency bands is done which are standardized for WBASNs, that is, 420 MHz, 868 MHz, 2.4 GHz, and so forth. Finally, a series of experiments are conducted to produce statistical results for DRT profile with respect to delay, reliability, and packet delivery ratio (PDR). The calculated results are verified through extensive simulations in the CASTALIA 3.2 framework using the OMNET++ network simulator. Muhammad Sajjad Akbar, Hongnian Yu, and Shuang Cang Copyright © 2016 Muhammad Sajjad Akbar et al. All rights reserved. A Flexible Online Camera Calibration Using Line Segments Wed, 06 Jan 2016 12:51:16 +0000 http://www.hindawi.com/journals/js/2016/2802343/ In order to make the general user take vision tasks more flexibly and easily, this paper proposes a new solution for the problem of camera calibration from correspondences between model lines and their noisy image lines in multiple images. In the proposed method the common planar items in hand with the standard size and structure are utilized as the calibration objects. The proposed method consists of a closed-form solution based on homography optimization, followed by a nonlinear refinement based on the maximum likelihood approach. To automatically recover the camera parameters linearly, we present a robust homography optimization method based on the edge model by redesigning the classic 3D tracking approach. In the nonlinear refinement procedure, the uncertainty of the image line segment is encoded in the error model, taking the finite nature of the observations into account. By developing the new error model between the model line and image line segment, the problem of the camera calibration is expressed in the probabilistic formulation. Simulation data is used to compare this method with the widely used planar pattern based method. Actual image sequences are also utilized to demonstrate the effectiveness and flexibility of the proposed method. Yueqiang Zhang, Langming Zhou, Haibo Liu, and Yang Shang Copyright © 2016 Yueqiang Zhang et al. All rights reserved. Intraframe Scene Capturing and Speed Measurement Based on Superimposed Image: New Sensor Concept for Vehicle Speed Measurement Wed, 06 Jan 2016 12:42:10 +0000 http://www.hindawi.com/journals/js/2016/8696702/ A vision based vehicle speed measurement method is presented in this paper. The proposed intraframe method calculates speed estimates based on a single frame of a single camera. With a special double exposure, a superimposed image can be obtained, where motion blur appears significantly only in the bright regions of the otherwise sharp image. This motion blur contains information of the movement of bright objects during the exposure. Most papers in the field of motion blur are aiming at the removal of this image degradation effect. In this work, we utilize it for a novel speed measurement approach. An applicable sensor structure and exposure-control system are also shown, as well as the applied image processing methods and experimental results. Mate Nemeth and Akos Zarandy Copyright © 2016 Mate Nemeth and Akos Zarandy. All rights reserved. Simulation of an Electromagnetic Acoustic Transducer Array by Using Analytical Method and FDTD Wed, 06 Jan 2016 09:23:26 +0000 http://www.hindawi.com/journals/js/2016/5451821/ Previously, we developed a method based on FEM and FDTD for the study of an Electromagnetic Acoustic Transducer Array (EMAT). This paper presents a new analytical solution to the eddy current problem for the meander coil used in an EMAT, which is adapted from the classic Deeds and Dodd solution originally intended for circular coils. The analytical solution resulting from this novel adaptation exploits the large radius extrapolation and shows several advantages over the finite element method (FEM), especially in the higher frequency regime. The calculated Lorentz force density from the analytical EM solver is then coupled to the ultrasonic simulations, which exploit the finite-difference time-domain (FDTD) method to describe the propagation of ultrasound waves, in particular for Rayleigh waves. Radiation pattern obtained with Hilbert transform on time-domain waveforms is proposed to characterise the sensor in terms of its beam directivity and field distribution along the steering angle, which can produce performance parameters for an EMAT array, facilitating the optimum design of such sensors. Yuedong Xie, Sergio Rodriguez, Wenbo Zhang, Zenghua Liu, and Wuliang Yin Copyright © 2016 Yuedong Xie et al. All rights reserved. An Object-Based Change Detection Approach Using Uncertainty Analysis for VHR Images Wed, 06 Jan 2016 09:21:39 +0000 http://www.hindawi.com/journals/js/2016/9078364/ This paper proposes an object-based approach to supervised change detection using uncertainty analysis for very high resolution (VHR) images. First, two temporal images are combined into one image by band stacking. Then, on the one hand, the stacked image is segmented by the statistical region merging (SRM) to generate segmentation maps; on the other hand, the stacked image is classified by the support vector machine (SVM) to produce a pixel-wise change detection map. Finally, the uncertainty analysis for segmented objects is implemented to integrate the segmentation map and pixel-wise change map at the appropriate scale and generate the final change map. Experiments were carried out with SPOT 5 and QuickBird data sets to evaluate the effectiveness of proposed approach. The results indicate that the proposed approach often generates more accurate change detection maps compared with some methods and reduces the effects of classification and segment scale on the change detection accuracy. The proposed method supplies an effective approach for the supervised change detection for VHR images. Ming Hao, Wenzhong Shi, Kazhong Deng, Hua Zhang, and Pengfei He Copyright © 2016 Ming Hao et al. All rights reserved. Decoupled Multicamera Sensing for Flexible View Generation Wed, 06 Jan 2016 09:15:53 +0000 http://www.hindawi.com/journals/js/2016/8137859/ Any sensing paradigm has three important components, namely, the actor, the sensor, and the environment. Traditionally, the sensors have been attached to either the actor or the environment. This restricts the kind of sensing that can be undertaken. We study a newer decoupled sensing paradigm, which separates the sensors from both the actor and the environment and tremendously increases the flexibility with which the scenes can be viewed. For example, instead of showing just one view, “how the environment sees the actor” or “how the actor sees the environment,” a viewer can choose to see either one or both of these views and even choose to see the scene from any desired position in any desired direction. We describe a methodology using mobile autonomous sensors to undertake such decoupled sensing and study the feasible number as well as the placement of such sensors. Also, we describe how the sensors can coordinate their movements around a moving actor so as to continue capturing the required views with minimum overall cost. The practical results obtained demonstrate the viability of the proposed approach. Vivek K. Singh, Danny Fernandes, Mohan Kankanhalli, and Thomas Haenselmann Copyright © 2016 Vivek K. Singh et al. All rights reserved. Organic Membranes for Selectivity Enhancement of Metal Oxide Gas Sensors Wed, 06 Jan 2016 09:03:01 +0000 http://www.hindawi.com/journals/js/2016/2435945/ We present the characterization of organic polyolefin and thermoplastic membranes for the enhancement of the selectivity of metal oxide (MOX) gas sensors. The experimental study is done based on theoretical considerations of the membrane characteristics. Through a broad screening of dense symmetric homo- and copolymers with different functional groups, the intrinsic properties such as the mobility or the transport of gases through the matrix were examined in detail. A subset of application-relevant gases was chosen for the experimental part of the study: H2, CH4, CO, CO2, NO2, ethanol, acetone, acetaldehyde, and water vapor. The gases have similar kinetic diameters and are therefore difficult to separate but have different functional groups and polarity. The concentration of the gases was based on the international indicative limit values (TWA, STEL). From the results, a simple relationship was to be found to estimate the permeability of various polar and nonpolar gases through gas permeation (GP) membranes. We used a broadband metal oxide gas sensor with a sensitive layer made of tin oxide with palladium catalyst (SnO2:Pd). Our aim was to develop a low-cost symmetrical dense polymer membrane to selectively detect gases with a MOX sensor. Thorsten Graunke, Katrin Schmitt, and Jürgen Wöllenstein Copyright © 2016 Thorsten Graunke et al. All rights reserved. Evaluation of Different Soil Salinity Mapping Using Remote Sensing Techniques in Arid Ecosystems, Saudi Arabia Wed, 06 Jan 2016 09:00:38 +0000 http://www.hindawi.com/journals/js/2016/7596175/ Land covers in Saudi Arabia are generally described as salty soils with sand dunes and sand sheets. Waterlogging and higher soil salinity are major challenges to sustaining agricultural practices in Saudi Arabia principally within closed drainage basins. Agricultural practices in Saudi Arabia were flourishing in the last two decades. The newly reclaimed lands were added annually and distributed all over the country. Irrigation techniques are mostly modernized to fulfill water saving strategies. Nevertheless, water resources in Saudi Arabia are under stress and groundwater levels are depleted rapidly due to heavy abstraction that may exceed crop water requirements in most of the cases due to high evaporation rates. The excess use of irrigational water leads to severe soil salinity problems. Applications of remote sensing technique in agricultural practices became widely distinctive and cover multidisciplinary principal interests on both local and regional levels. The most important remote sensing applications in agricultural practices are vegetation indices which are related to vegetation and water especially in an arid environment. Soil salinity mapping in an arid ecosystem using remote sensing data is a demanding task. Several soil salinity indices were implemented and evaluated to detect soil salinity effectively and quantitatively. Thematic maps of soil salinity were satisfactorily produced and assessed. Mohamed Elhag Copyright © 2016 Mohamed Elhag. All rights reserved.