Journal of Sensors The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. PKDIP: Efficient Public-Key-Based Data Integrity Protection for Wireless Image Sensors Thu, 25 Jun 2015 07:00:15 +0000 Due to limited energy of “wireless image sensors (WISs),” existing data integrity protection mechanisms typically employ a hash-function-based signing algorithm to generate “message authentication codes (MACs)” for long image frames. However, hash-function-based signing algorithm requires the WIS and the “end user (EU)” sharing a secret, which leads to a new security issue: Once the EU becomes malicious due to some reasons, it will be able to forge the WIS’s data since it holds the shared secret. Therefore, public-key cryptography is desirable. Unfortunately, public-key cryptographic operations are quite time-consuming for energy-restrained WISs. Facing this dilemma, we present a novel data integrity protection protocol named PKDIP in this paper. Similar to the mechanisms of this field, PKDIP generates MACs for data integrity protection. However, different from other well-known approaches, PKDIP introduces the “Montgomery Modular Multiplication (MontMM)” technique to current public-key-based signing algorithms. Since MontMM is much more efficient than hash functions, PKDIP can reduce the signing cost significantly. Experimental results show PKDIP can even be more efficient than hash-function-based schemes. Changsheng Wan, Juan Zhang, and Jie Huang Copyright © 2015 Changsheng Wan et al. All rights reserved. General Voltage Feedback Circuit Model in the Two-Dimensional Networked Resistive Sensor Array Tue, 23 Jun 2015 11:53:40 +0000 To analyze the feature of the two-dimensional networked resistive sensor array, we firstly proposed a general model of voltage feedback circuits (VFCs) such as the voltage feedback non-scanned-electrode circuit, the voltage feedback non-scanned-sampling-electrode circuit, and the voltage feedback non-scanned-sampling-electrode circuit. By analyzing the general model, we then gave a general mathematical expression of the effective equivalent resistor of the element being tested in VFCs. Finally, we evaluated the features of VFCs with simulation and test experiment. The results show that the expression is applicable to analyze the VFCs’ performance of parameters such as the multiplexers’ switch resistors, the nonscanned elements, and array size. JianFeng Wu, Lei Wang, and JianQing Li Copyright © 2015 JianFeng Wu et al. All rights reserved. Model-Checking Driven Design of QoS-Based Routing Protocol for Wireless Sensor Networks Mon, 22 Jun 2015 08:07:17 +0000 Accurate and reliable routing protocols with Quality of Service (QoS) support determine the mission-critical application efficiency in WSNs. This paper proposes a model-checking design driven framework for designing the QoS-based routing protocols of WSNs, which involves the light-weight design process, the timed automata model, and the alternative QoS verification properties. The accurate feedback of continually model checking in the iterative design process effectively stimulates the parameter tuning of the protocols. We demonstrate the straightforward and modular characteristics of the proposed framework in designing a prototype QoS-based routing protocol. The prototype study shows that the model-checking design framework may complement other design methods and ensure the QoS implementation of the QoS-based routing protocol design for WSNs. Zhi Chen, Ya Peng, and Wenjing Yue Copyright © 2015 Zhi Chen et al. All rights reserved. Local Interaction Simulation Approach for Fault Detection in Medical Ultrasonic Transducers Sun, 21 Jun 2015 09:46:18 +0000 A new approach is proposed for modelling medical ultrasonic transducers operating in air. The method is based on finite elements and the local interaction simulation approach. The latter leads to significant reductions of computational costs. Transmission and reception properties of the transducer are analysed using in-air reverberation patterns. The proposed approach can help to provide earlier detection of transducer faults and their identification, reducing the risk of misdiagnosis due to poor image quality. Z. Hashemiyan, P. Packo, W. J. Staszewski, T. Uhl, and P. K. Verma Copyright © 2015 Z. Hashemiyan et al. All rights reserved. Optical Fiber Sensor Experimental Research Based on the Theory of Bending Loss Applied to Monitoring Differential Settlement at the Earth-Rock Junction Wed, 17 Jun 2015 11:56:14 +0000 Considering the differential settlement in the junction between the structure perpendicular to the dike and the body and foundation of dike (called the earth-rock junction in this paper) during runtime, an experimental investigation of optical fiber sensor monitoring was conducted. Based on the sensing mechanism of single-mode optical fiber bending loss, the experiment focused on the influence of the bending radius of an optical fiber on the bending loss. In view of the characteristics of the differential settlement in the earth-rock junction, we designed a butterfly-type optical fiber sensor and composite optical fiber sensor for monitoring device in monitoring the differential settlement to enlarge the monitoring range and improve the sensibility of optical fiber sensor. Based on the research on the working principle and bending properties of the composite optical fiber monitoring device, we conducted experiments on the bending of the composite optical fiber sensor monitoring device and the use of the device for monitoring the differential settlement. These experiments verified the feasibility of the composite optical fiber sensor monitoring device at monitoring the differential settlement in the earth-rock junction. Jianchun Qiu, Dongjian Zheng, Kai Zhu, Bin Fang, and Lin Cheng Copyright © 2015 Jianchun Qiu et al. All rights reserved. Quantitative Assessment of ADL: A Pilot Study of Upper Extremity Reaching Tasks Wed, 17 Jun 2015 11:54:55 +0000 Effective telerehabilitation technologies enable patients with certain physiological disabilities to engage in rehabilitative exercises for performing Activities of Daily Living (ADLs). Therefore, training and assessment scenarios for the performance of ADLs are vital for the promotion for telerehabilitation. In this paper we investigate quantitatively and automatically assessing patient’s kinematic ability to perform functional upper extremity reaching tasks. The shape of the movement trajectory and the instantaneous acceleration of kinematically crucial body parts, such as wrists, are used to compute the approximate entropy of the motions to represent stability (smoothness) in addition to the duration of the activity. Computer simulations were conducted to illustrate the consistency, sensitivity and robustness of the proposed method. A preliminary experiment with kinematic data captured from healthy subjects mimicking a reaching task with dyskinesia showed a high degree of correlation (Cohen’s kappa 0.85 with ) between a human observer and the proposed automatic classification tool in terms of assigning the datasets to various levels to represent the subjects’ kinematic abilities to perform reaching tasks. This study supported the use of Microsoft Kinect to quantitatively evaluate the ability of individuals with involuntary movements to perform an upper extremity reaching task. Saiyi Li, Pubudu N. Pathirana, Mary P. Galea, Goetz Ottmann, and Fary Khan Copyright © 2015 Saiyi Li et al. All rights reserved. Sensors Based on Thin-Film Coated Cladding Removed Multimode Optical Fiber and Single-Mode Multimode Single-Mode Fiber: A Comparative Study Sun, 14 Jun 2015 13:53:45 +0000 Two simple optical fibre structures that do not require the inscription of a grating, a cladding removed multimode optical fibre (CRMOF) and a single-mode multimode single-mode structure (SMS), are compared in terms of their adequateness for sensing once they are coated with thin-films. The thin-film deposited (TiO2/PSS) permits increasing the sensitivity to surrounding medium refractive index. The results obtained can be extrapolated to other fields such as biological or chemical sensing just by replacing the thin-film by a specific material. Ignacio Del Villar, Abian B. Socorro, Miguel Hernaez, Jesús M. Corres, Carlos R. Zamarreño, Pedro Sanchez, Francisco J. Arregui, and Ignacio R. Matias Copyright © 2015 Ignacio Del Villar et al. All rights reserved. Data Transmission Scheme Using Mobile Sink in Static Wireless Sensor Network Mon, 08 Jun 2015 12:20:51 +0000 Multihop communication in wireless sensor network (WSN) brings new challenges in reliable data transmission. Recent work shows that data collection from sensor nodes using mobile sink minimizes multihop data transmission and improves energy efficiency. However, due to continuous movements, mobile sink has limited communication time to collect data from sensor nodes, which results in rapid depletion of node’s energy. Therefore, we propose a data transmission scheme that addresses the aforementioned constraints. The proposed scheme first finds out the group based region on the basis of localization information of the sensor nodes and predefined trajectory information of a mobile sink. After determining the group region in the network, selection of master nodes is made. The master nodes directly transmit their data to the mobile sink upon its arrival at their group region through restricted flooding scheme. In addition, the agent node concept is introduced for swapping of the role of the master nodes in each group region. The master node when consuming energy up to a certain threshold, neighboring node with second highest residual energy is selected as an agent node. The mathematical analysis shows that the selection of agent node maximizes the throughput while minimizing transmission delay in the network. Awais Ahmad, M. Mazhar Rathore, Anand Paul, and Bo-Wei Chen Copyright © 2015 Awais Ahmad et al. All rights reserved. Effect of the Tip Size on AFM Cantilever Based Force Sensor Mon, 08 Jun 2015 08:45:49 +0000 Atomic force microscopy (AFM) cantilever is a widely used end effector for precise force sensing and micro-nanomanipulation at small scale. However, in current researches, the effect of the cantilever tip on the force sensing and manipulation accuracy is rarely considered. In this paper, we investigate how the tip size of the end effector affects the measurement accuracy of the cell adhesion force. First, several end effectors with different tip sizes are fabricated from the same AFM cantilever via focused ion beam (FIB) etching. Then, the single cell detachment force is measured at the same experiment condition by these end effectors, respectively. The results indicate that the sensed adhesion force is susceptible to the tip size of the end effector obviously. In addition, the precision of cell manipulation is also regulated by the contact area between the cell and end effector greatly. These findings will benefit our in-depth understanding on the force interaction at small scale and will provide valid reference for the development of high-precision force sensor and manipulation. Yajing Shen Copyright © 2015 Yajing Shen. All rights reserved. Automated Waterline Detection in the Wadden Sea Using High-Resolution TerraSAR-X Images Sun, 07 Jun 2015 07:24:16 +0000 We present an algorithm for automatic detection of the land-water-line from TerraSAR-X images acquired over the Wadden Sea. In this coastal region of the southeastern North Sea, a strip of up to 20 km of seabed falls dry during low tide, revealing mudflats and tidal creeks. The tidal currents transport sediments and can change the coastal shape with erosion rates of several meters per month. This rate can be strongly increased by storm surges which also cause flooding of usually dry areas. Due to the high number of ships traveling through the Wadden Sea to the largest ports of Germany, frequent monitoring of the bathymetry is also an important task for maritime security. For such an extended area and the required short intervals of a few months, only remote sensing methods can perform this task efficiently. Automating the waterline detection in weather-independent radar images provides a fast and reliable way to spot changes in the coastal topography. The presented algorithm first performs smoothing, brightness thresholding, and edge detection. In the second step, edge drawing and flood filling are iteratively performed to determine optimal thresholds for the edge drawing. In the last step, small misdetections are removed. Stefan Wiehle and Susanne Lehner Copyright © 2015 Stefan Wiehle and Susanne Lehner. All rights reserved. Dynamic Allan Variance Analysis Method with Time-Variant Window Length Based on Fuzzy Control Wed, 03 Jun 2015 12:35:15 +0000 To solve the problem that dynamic Allan variance (DAVAR) with fixed length of window cannot meet the identification accuracy requirement of fiber optic gyro (FOG) signal over all time domains, a dynamic Allan variance analysis method with time-variant window length based on fuzzy control is proposed. According to the characteristic of FOG signal, a fuzzy controller with the inputs of the first and second derivatives of FOG signal is designed to estimate the window length of the DAVAR. Then the Allan variances of the signals during the time-variant window are simulated to obtain the DAVAR of the FOG signal to describe the dynamic characteristic of the time-varying FOG signal. Additionally, a performance evaluation index of the algorithm based on radar chart is proposed. Experiment results show that, compared with different fixed window lengths DAVAR methods, the change of FOG signal with time can be identified effectively and the evaluation index of performance can be enhanced by 30% at least by the DAVAR method with time-variant window length based on fuzzy control. Shanshan Gu, Jianye Liu, Qinghua Zeng, Shaojun Feng, and Pin Lv Copyright © 2015 Shanshan Gu et al. All rights reserved. Energy-Efficient Data Fusion Technique and Applications in Wireless Sensor Networks Tue, 02 Jun 2015 11:52:08 +0000 Yun Liu, Qing-An Zeng, and Ying-Hong Wang Copyright © 2015 Yun Liu et al. All rights reserved. Theoretical Modeling and Implementation of Traveling Wave Sensor Based on PCB Coils Tue, 02 Jun 2015 07:49:48 +0000 Based on analyzing characteristics of Rogowski coil, a new type of PCB traveling wave sensor with simple structure, high linearity, and anti-interference ability is proposed. The sensor has fine physical structure, which can effectively resist external electromagnetic interference by anti-interference measurement. In addition, it can greatly improve mutual inductance based on simple combinations. Simulations show that the new PCB traveling wave sensor can validly extract and deliver traveling wave signal and therefore realize fault location and protection accurately. Zewen Li, Tuofu Deng, Xiangjun Zeng, Feng Deng, and Lei Shu Copyright © 2015 Zewen Li et al. All rights reserved. Triaxial Accelerometer Error Coefficients Identification with a Novel Artificial Fish Swarm Algorithm Tue, 02 Jun 2015 07:33:46 +0000 Artificial fish swarm algorithm (AFSA) is one of the state-of-the-art swarm intelligence techniques, which is widely utilized for optimization purposes. Triaxial accelerometer error coefficients are relatively unstable with the environmental disturbances and aging of the instrument. Therefore, identifying triaxial accelerometer error coefficients accurately and being with lower costs are of great importance to improve the overall performance of triaxial accelerometer-based strapdown inertial navigation system (SINS). In this study, a novel artificial fish swarm algorithm (NAFSA) that eliminated the demerits (lack of using artificial fishes’ previous experiences, lack of existing balance between exploration and exploitation, and high computational cost) of AFSA is introduced at first. In NAFSA, functional behaviors and overall procedure of AFSA have been improved with some parameters variations. Second, a hybrid accelerometer error coefficients identification algorithm has been proposed based on NAFSA and Monte Carlo simulation (MCS) approaches. This combination leads to maximum utilization of the involved approaches for triaxial accelerometer error coefficients identification. Furthermore, the NAFSA-identified coefficients are testified with 24-position verification experiment and triaxial accelerometer-based SINS navigation experiment. The priorities of MCS-NAFSA are compared with that of conventional calibration method and optimal AFSA. Finally, both experiments results demonstrate high efficiency of MCS-NAFSA on triaxial accelerometer error coefficients identification. Yanbin Gao, Lianwu Guan, and Tingjun Wang Copyright © 2015 Yanbin Gao et al. All rights reserved. Design and Implementation of Energy Efficiency in HVAC Systems Based on Robust PID Control for Industrial Applications Mon, 01 Jun 2015 13:26:13 +0000 Energy efficiency in heating, ventilating, and air-conditioning (HVAC) systems is a primary concern in process projects, since the energy consumption has the highest percentage in HVAC for all processes. Without sacrifice of thermal comfort, to reset the suitable operating parameters, such as the humidity and air temperature, would have energy saving with immediate effect. In this paper, the simulation-optimization approach described the effective energy efficiency for HVAC systems which are used in industrial process. Due to the complex relationship of the HVAC system parameters, it is necessary to suggest optimum settings for different operations in response to the dynamic cooling loads and changing weather conditions during a year. Proportional-integral-derivative (PID) programming was developed which can effectively handle the discrete, nonlinear and highly constrained optimization problems. Energy efficiency process has been made by controlling of alternative current (AC) drivers for ventilation and exhaust fans, according to supplied air flow capacity and differential air pressure between supplied and exhaust air. Supervisory controller software was developed by using programmable controllers and human machine interface (HMI) units. The new designed HVAC control system would have a saving potential of about 40% as compared to the existing operational settings, without any extra cost. Muharrem Imal Copyright © 2015 Muharrem Imal. All rights reserved. A Cluster-Based Fuzzy Fusion Algorithm for Event Detection in Heterogeneous Wireless Sensor Networks Mon, 01 Jun 2015 11:47:24 +0000 As limited energy is one of the tough challenges in wireless sensor networks (WSN), energy saving becomes important in increasing the lifecycle of the network. Data fusion enables combining information from several sources thus to provide a unified scenario, which can significantly save sensor energy and enhance sensing data accuracy. In this paper, we propose a cluster-based data fusion algorithm for event detection. We use -means algorithm to form the nodes into clusters, which can significantly reduce the energy consumption of intracluster communication. Distances between cluster heads and event and energy of clusters are fuzzified, thus to use a fuzzy logic to select the clusters that will participate in data uploading and fusion. Fuzzy logic method is also used by cluster heads for local decision, and then the local decision results are sent to the base station. Decision-level fusion for final decision of event is performed by base station according to the uploaded local decisions and fusion support degree of clusters calculated by fuzzy logic method. The effectiveness of this algorithm is demonstrated by simulation results. ZiQi Hao, ZhenJiang Zhang, and Han-Chieh Chao Copyright © 2015 ZiQi Hao et al. All rights reserved. Minimum Cost Data Aggregation for Wireless Sensor Networks Computing Functions of Sensed Data Mon, 01 Jun 2015 11:31:03 +0000 We consider a problem of minimum cost (energy) data aggregation in wireless sensor networks computing certain functions of sensed data. We use in-network aggregation such that data can be combined at the intermediate nodes en route to the sink. We consider two types of functions: firstly the summation-type which includes sum, mean, and weighted sum, and secondly the extreme-type which includes max and min. However for both types of functions the problem turns out to be NP-hard. We first show that, for sum and mean, there exist algorithms which can approximate the optimal cost by a factor logarithmic in the number of sources. For weighted sum we obtain a similar result for Gaussian sources. Next we reveal that the problem for extreme-type functions is intrinsically different from that for summation-type functions. We then propose a novel algorithm based on the crucial tradeoff in reducing costs between local aggregation of flows and finding a low cost path to the sink: the algorithm is shown to empirically find the best tradeoff point. We argue that the algorithm is applicable to many other similar types of problems. Simulation results show that significant cost savings can be achieved by the proposed algorithm. Chao Chen, Kyogu Lee, Joon-Sang Park, and Seung Jun Baek Copyright © 2015 Chao Chen et al. All rights reserved. GTDM: A DTN Routing on Noncooperative Game Theory in a City Environment Mon, 01 Jun 2015 11:26:54 +0000 The performance of delay tolerant networks (DTNs) can be influenced by movement model in different application environments. The existing routing algorithms of DTNs do not meet the current city environments due to the large differences in node densities, social characteristics, and limited energy. The key indicators of DTNs such as success delivery ratio, average delivery latency, network lifetime, and network overhead ratio can influence the performances of civil DTNs applications. Aiming to improve the key indicators of DTNs in city environments, this paper presents a fixed sink station based structure and a more proper routing algorithm named Game Theory Based Decision Making (GTDM). GTDM shows decision-making process for neighborhood selection and packet delivering strategy which is based on the noncooperative game theory method and city environment characteristics. GTDM performance is evaluated using numerical simulations under Working Day Movement (WDM) model and the results suggested that GTDM outperforms other traditional DTNs routing approaches, such as Epidemic and Prophet algorithms. Wenzao Li, Feng Lin, Jiliu Zhou, and Yan Wang Copyright © 2015 Wenzao Li et al. All rights reserved. Secure Data Fusion in Wireless Multimedia Sensor Networks via Compressed Sensing Mon, 01 Jun 2015 10:08:15 +0000 The paper proposes a novel secure data fusion strategy based on compressed image sensing and watermarking; namely, the algorithm exploits the sparsity in the image encryption. The approach relies on -norm regularization, common in compressive sensing, to enhance the detection of sparsity over wireless multimedia sensor networks. The resulting algorithms endow sensor nodes with learning abilities and allow them to learn the sparse structure from the still image data, and also utilize the watermarking approach to achieve authentication mechanism. We provide the total transmission volume and the energy consumption performance analysis of each node, and summarize the peak signal to noise ratio values of the proposed method. We also show how to adaptively select the sampling parameter. Simulation results illustrate the advantage of the proposed strategy for secure data fusion. Rui Gao, Yingyou Wen, and Hong Zhao Copyright © 2015 Rui Gao et al. All rights reserved. An Improved Ant Colony Routing Algorithm for WSNs Mon, 01 Jun 2015 08:57:03 +0000 Ant colony algorithm is a classical routing algorithm. And it are used in a variety of application because it is economic and self-organized. However, the routing algorithm will expend huge amounts of energy at the beginning. In the paper, based on the idea of Dijkstra algorithm, the improved ant colony algorithm was proposed to balance the energy consumption of networks. Through simulation and comparison with basic ant colony algorithms, it is obvious that improved algorithm can effectively balance energy consumption and extend the lifetime of WSNs. Tan Zhi and Zhang Hui Copyright © 2015 Tan Zhi and Zhang Hui. All rights reserved. Electrophoretic Deposition of SnO2 Nanoparticles and Its LPG Sensing Characteristics Wed, 27 May 2015 13:04:16 +0000 Homogenized nanoparticles (60 nm) in acetylacetone mediums, both with and without iodine, were deposited onto platinum coated alumina substrate and interdigital electrodes using the electrophoretic deposition (EPD) method for gas sensor applications. Homogeneous and porous film layers were processed and analyzed at various coating times and voltages. The structure of the deposited films was characterized by a scanning electron microscopy (SEM). The gas sensing properties of the films were investigated using liquid petroleum gas (LPG) for various lower explosive limits (LEL). The results showed that porous, crack-free, and homogeneous films were achieved for 5 and 15 sec at 100 and 150 V EPD parameters using an iodine-free acetylacetone based suspension. The optimum sintering for the deposited nanoparticles was observed at 500°C for 5 min. The results showed that the sensitivity of the films was increased with the operating temperature. The coated films with EPD demonstrated a better sensitivity for the 20 LEL LPG concentrations at a 450°C operating temperature. The maximum sensitivity of the sensors at 450°C to 20 LEL LPG was 30. Göktuğ Günkaya, Mevlüt Gürbüz, and Aydın Doğan Copyright © 2015 Göktuğ Günkaya et al. All rights reserved. A Method for Measurement of Absolute Angular Position and Application in a Novel Electromagnetic Encoder System Wed, 27 May 2015 13:00:05 +0000 For the encoders, especially the sine-cosine magnetic ones, a new method to measure absolute angular position is proposed in the paper. In the method, the code disc of the encoder has only two circle tracks and each one was divided into and () equal code cells. The cell angles, changing from 0° to 360° between any two neighboring code cells, are defined to represent any position on the code disc. The position value of the same point can be represented by different cell angle values of different tracks and the absolute angular position of the point can be obtained by the difference value between the cell angle value of the outer track and the inner one. To validate the correctness of the method theoretically, the derivation process of the method was provided. An electromagnetic encoder system was designed and the experimental platform was established to test the method. The experimental results indicate that the electromagnetic encoder can measure the absolute angular position. Besides, it shows that the method is easy to be realized in algorithm and can reduce computational complexity and decrease dimension of the encoder. Zijian Zhang, Yangyang Dong, Fenglei Ni, Minghe Jin, and Hong Liu Copyright © 2015 Zijian Zhang et al. All rights reserved. Removal of False Blood Vessels Using Shape Based Features and Image Inpainting Tue, 26 May 2015 14:23:08 +0000 Automated quantification of blood vessels in human retina is the fundamental step in designing any computer-aided diagnosis system for ophthalmic disorders. Detection and analysis of variations in blood vessels can be used to diagnose several ocular diseases like diabetic retinopathy. Diabetic Retinopathy is a progressive vascular disorder caused due to variations in blood vessels of retina. These variations bring different abnormalities like lesions, exudates, and hemorrhages in human retina which make the vessel detection problematic. Therefore, automated retinal analysis is required to cater the effect of lesions while segmenting blood vessels. The proposed framework presents two improved approaches to carry out vessel segmentation in the presence of lesions. The paper mainly aims to extract true vessels by reducing the effect of abnormal structures significantly. First method is a supervised approach which extracts true vessels by performing region based analysis of retinal image, while second method intends to remove lesions before extracting blood vessels by using an inpainting technique. Both methods are evaluated on STARE and DRIVE and on our own database AFIO. Experimental results demonstrate the excellence of the proposed system. Amna Waheed, Zahra Waheed, M. Usman Akram, and Arslan Shaukat Copyright © 2015 Amna Waheed et al. All rights reserved. Using Bayesian Inference Framework towards Identifying Gas Species and Concentration from High Temperature Resistive Sensor Array Data Mon, 25 May 2015 13:17:58 +0000 High temperature gas sensors have been highly demanded for combustion process optimization and toxic emissions control, which usually suffer from poor selectivity. In order to solve this selectivity issue and identify unknown reducing gas species (CO, CH4, and CH8) and concentrations, a high temperature resistive sensor array data set was built in this study based on 5 reported sensors. As each sensor showed specific responses towards different types of reducing gas with certain concentrations, based on which calibration curves were fitted, providing benchmark sensor array response database, then Bayesian inference framework was utilized to process the sensor array data and build a sample selection program to simultaneously identify gas species and concentration, by formulating proper likelihood between input measured sensor array response pattern of an unknown gas and each sampled sensor array response pattern in benchmark database. This algorithm shows good robustness which can accurately identify gas species and predict gas concentration with a small error of less than 10% based on limited amount of experiment data. These features indicate that Bayesian probabilistic approach is a simple and efficient way to process sensor array data, which can significantly reduce the required computational overhead and training data. Yixin Liu, Kai Zhou, and Yu Lei Copyright © 2015 Yixin Liu et al. All rights reserved. Autonomic Context-Aware Wireless Sensor Networks Mon, 25 May 2015 11:24:33 +0000 Autonomic Computing allows systems like wireless sensor networks (WSN) to self-manage computing resources in order to extend their autonomy as much as possible. In addition, contextualization tasks can fuse two or more different sensor data into a more meaningful information. Since these tasks usually run in a single centralized context server (e.g., sink node), the massive volume of data generated by the wireless sensors can lead to a huge information overload in such server. Here we propose DAIM, a distributed autonomic inference machine distributed which allows the sensor nodes to do self-management and contextualization tasks based on fuzzy logic. We have evaluated DAIM in a real sensor network taking into account other inference machines. Experimental results illustrate that DAIM is an energy-efficient contextualization method for WSN, reducing 48.8% of the number of messages sent to the context servers while saving 19.5% of the total amount of energy spent in the network. Nídia G. S. Campos, Danielo G. Gomes, Flávia C. Delicato, Augusto J. V. Neto, Luci Pirmez, and José Neuman de Souza Copyright © 2015 Nídia G. S. Campos et al. All rights reserved. Towards a Carbon Nanotube Intermodulation Product Sensor for Nonlinear Energy Harvesting Mon, 25 May 2015 06:52:35 +0000 It is critically important in designing RF receiver front ends to handle high power jammers and other strong interferers. Instead of blocking incoming energy or dissipating it as heat, we investigate the possibility of redirecting that energy for harvesting and storage. The approach is based on channelizing a high power signal into a previously unknown circuit element which serves as a passive intermodulation device. This intermodulation component must produce a hysteretic current-voltage curve to be useful as an energy harvester. Here we demonstrate a method by which carbon nanotube transistors produce the necessary hysteretic - curves. Such devices can be tailored to the desired frequency by introducing functional groups to the nanotubes. These effects controllably enhance the desired behavior, namely, hysteretic nonlinearity in the transistors’ - characteristic. Combining these components with an RF energy harvester may one day enable the reuse of inbound jamming energy for standard back end radio components. Mitchell B. Lerner, Brett Goldsmith, John Rockway, and Israel Perez Copyright © 2015 Mitchell B. Lerner et al. All rights reserved. A Low-Power and Low-Voltage Power Management Strategy for On-Chip Micro Solar Cells Sun, 24 May 2015 07:19:07 +0000 Fundamental characteristics of on-chip micro solar cell (MSC) structures were investigated in this study. Several MSC structures using different layers in three different CMOS processes were designed and fabricated. Effects of PN junction structure and process technology on solar cell performance were measured. Parameters for low-power and low-voltage implementation of power management strategy and boost converter based circuits utilizing fractional voltage maximum power point tracking (FVMPPT) algorithm were determined. The FVMPPT algorithm works based on the fraction between the maximum power point operation voltage and the open circuit voltage of the solar cell structure. This ratio is typically between 0.72 and 0.78 for commercially available poly crystalline silicon solar cells that produce several watts of power under typical daylight illumination. Measurements showed that the fractional voltage ratio is much higher and fairly constant between 0.82 and 0.85 for on-chip mono crystalline silicon micro solar cell structures that produce micro watts of power. Mono crystalline silicon solar cell structures were observed to result in better power fill factor (PFF) that is higher than 74% indicating a higher energy harvesting efficiency. Ismail Cevik and Suat U. Ay Copyright © 2015 Ismail Cevik and Suat U. Ay. All rights reserved. Parameter Modeling Analysis and Experimental Verification on Magnetic Shielding Cylinder of All-Optical Atomic Spin Magnetometer Thu, 21 May 2015 13:33:17 +0000 The ultrahigh sensitivity atomic spin magnetometer as the magnetic measurement sensor has received much concern. The performance of the magnetic shielding cylinder is one of the key factors constraining the atomic spin magnetometer’s sensitivity. In order to effectively improve the performances of the magnetic shielding, the parameter optimization models of the magnetic shielding cylinder were established in this paper. Under the condition of changing only one parameter while the others keeping constant, the effects of various parameters influencing the axial shielding coefficient were comprehensively analyzed, and the results showed that the smaller the innermost length, the innermost radius, and the radial spacing were, and the greater the axial spacing was, the better the shielding performance could be obtained. According to these results and the actual needs, the magnetic shielding cylinder was optimally designed, and then the shielding effects were simulated via the software Ansoft. The simulation results showed that the optimized magnetic shielding cylinder had the advantages of small size, high shielding performance, and lager uniformity than that of the nonoptimized one. The actual measurement results showed that the residual magnetism in the optimized magnetic shielding cylinder was below 0.1 nT, which was 2~4 times lower than the nonoptimized one. Hong Zhang, Sheng Zou, Xi-Yuan Chen, and Wei Quan Copyright © 2015 Hong Zhang et al. All rights reserved. Characterization and Optimization of a Single-Transistor Active Pixel Image Sensor with Floating Junction Connected to Floating Gate Thu, 21 May 2015 11:38:52 +0000 The application of semifloating gate transistor (SFGT) as the single-transistor active pixel image sensor (APS) is investigated in this paper. This single-transistor (1T) APS can realize the functions of the conventional 3T CMOS image sensor. The device operation mechanism, optimization methods, and transient behavior measurements will be discussed. Because the floating junction of this device is connected to the floating gate, special behaviors such as floating gate voltage pinning effects were observed. The transient time measurement emulating the exposure procedure also confirmed the light sensing function as a single-transistor image sensor. Xin-Yan Liu, Jun Wu, Xiao-Yong Liu, Shuai Zhang, Xi Lin, Chun-Min Zhang, Peng-Fei Wang, and David Wei Zhang Copyright © 2015 Xin-Yan Liu et al. All rights reserved. EEG Signal Quality of a Subcutaneous Recording System Compared to Standard Surface Electrodes Wed, 20 May 2015 06:57:24 +0000 Purpose. We provide a comprehensive verification of a new subcutaneous EEG recording device which promises robust and unobtrusive measurements over ultra-long time periods. The approach is evaluated against a state-of-the-art surface EEG electrode technology. Materials and Methods. An electrode powered by an inductive link was subcutaneously implanted on five subjects. Surface electrodes were placed at sites corresponding to the subcutaneous electrodes, and the EEG signals were evaluated with both quantitative (power spectral density and coherence analysis) and qualitative (blinded subjective scoring by neurophysiologists) analysis. Results. The power spectral density and coherence analysis were very similar during measurements of resting EEG. The scoring by neurophysiologists showed a higher EEG quality for the implanted system for different subject states (eyes open and eyes closed). This was most likely due to higher amplitude of the subcutaneous signals. During periods with artifacts, such as chewing, blinking, and eye movement, the two systems performed equally well. Conclusions. Subcutaneous measurements of EEG with the test device showed high quality as measured by both quantitative and more subjective qualitative methods. The signal might be superior to surface EEG in some aspects and provides a method of ultra-long term EEG recording in situations where this is required and where a small number of EEG electrodes are sufficient. Jonas Duun-Henriksen, Troels Wesenberg Kjaer, David Looney, Mary Doreen Atkins, Jens Ahm Sørensen, Martin Rose, Danilo P. Mandic, Rasmus Elsborg Madsen, and Claus Bogh Juhl Copyright © 2015 Jonas Duun-Henriksen et al. All rights reserved.