Journal of Sensors http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Automatic Fusion of Hyperspectral Images and Laser Scans Using Feature Points Tue, 28 Jul 2015 14:29:02 +0000 http://www.hindawi.com/journals/js/2015/415361/ Automatic fusion of different kinds of image datasets is so intractable with diverse imaging principle. This paper presents a novel method for automatic fusion of two different images: 2D hyperspectral images acquired with a hyperspectral camera and 3D laser scans obtained with a laser scanner, without any other sensor. Only a few corresponding feature points are used, which are automatically extracted from a scene viewed by the two sensors. Extraction method of feature points relies on SURF algorithm and camera model, which can convert a 3D laser scan into a 2D laser image with the intensity of the pixels defined by the attributes in the laser scan. Moreover, Collinearity Equation and Direct Linear Transformation are used to create the initial corresponding relationship of the two images. Adjustment is also used to create corrected values to eliminate errors. The experimental result shows that this method is successfully validated with images collected by a hyperspectral camera and a laser scanner. Xiao Zhang, Aiwu Zhang, and Xiangang Meng Copyright © 2015 Xiao Zhang et al. All rights reserved. Hybrid Motion Planning Method for Autonomous Robots Using Kinect Based Sensor Fusion and Virtual Plane Approach in Dynamic Environments Tue, 28 Jul 2015 14:18:57 +0000 http://www.hindawi.com/journals/js/2015/471052/ A new reactive motion planning method for an autonomous vehicle in dynamic environments is proposed. The new dynamic motion planning method combines a virtual plane based reactive motion planning technique with a sensor fusion based obstacle detection approach, which results in improving robustness and autonomy of vehicle navigation within unpredictable dynamic environments. The key feature of the new reactive motion planning method is based on a local observer in the virtual plane which allows the effective transformation of complex dynamic planning problems into simple stationary in the virtual plane. In addition, a sensor fusion based obstacle detection technique provides the pose estimation of moving obstacles by using a Kinect sensor and a sonar sensor, which helps to improve the accuracy and robustness of the reactive motion planning approach in uncertain dynamic environments. The performance of the proposed method was demonstrated through not only simulation studies but also field experiments using multiple moving obstacles even in hostile environments where conventional method failed. Doopalam Tuvshinjargal, Byambaa Dorj, and Deok Jin Lee Copyright © 2015 Doopalam Tuvshinjargal et al. All rights reserved. Applications of Polarimetric SAR Tue, 28 Jul 2015 11:48:49 +0000 http://www.hindawi.com/journals/js/2015/316391/ Jian Yang, Yoshio Yamaguchi, Jong-Sen Lee, Ridha Touzi, and Wolfgang-Martin Boerner Copyright © 2015 Jian Yang et al. All rights reserved. Smart Sensing Technologies and Their Applications in Civil Infrastructures Tue, 28 Jul 2015 06:37:54 +0000 http://www.hindawi.com/journals/js/2015/265106/ Hong-Hu Zhu, Fei Dai, Zhenhua Zhu, Tuan Guo, and Xiao-Wei Ye Copyright © 2015 Hong-Hu Zhu et al. All rights reserved. A Comparative Study on Frequency Sensitivity of a Transmission Tower Mon, 27 Jul 2015 14:02:50 +0000 http://www.hindawi.com/journals/js/2015/610416/ Sensitivity analysis can take structural parameters as variable and achieve the relationship only with one time analysis, which will dramatically reduce the analytical work especially for large scale structures. The comparative study on frequency sensitivity of a transmission tower is actively carried out in this study. The three-dimensional analytical model of a transmission tower is established by using the finite element (FE) method. The sensitivity coefficients to natural frequencies are deduced based on the equation of motion of the tower. In addition, the expression of the frequency sensitivity to Young’s modulus, density of material, the cross area of members, torsional stiffness, and bending moment inertia is proposed. A real transmission tower constructed in China is taken as an example to examine the feasibility and reliability of the proposed sensitivity computation approach. An intensive parametric study is conducted in detail in order to compare the sensitivity coefficients of different physical parameters. The work on an example structure indicated that the magnitudes of the sensitivity coefficients of Young’s modulus, the density, and the cross area are much larger than those of the torsional stiffness and the bending moment inertia. Peng-yun Li, Bo Chen, Wen-ping Xie, and Xiang Xiao Copyright © 2015 Peng-yun Li et al. All rights reserved. Distributed Measurement of Temperature for PCC Energy Pile Using BOFDA Mon, 27 Jul 2015 13:22:04 +0000 http://www.hindawi.com/journals/js/2015/610473/ PCC energy pile is a new technology for sustainable development of urban areas. Learning and understanding the temperature variation of PCC energy pile are very important to its development and application. In this study, the Brillouin optical frequency domain analysis (BOFDA) technology is firstly used to measure the temperature variation of PCC energy pile from a model test. The aim is to provide an optical fiber sensing method for monitoring the temperature distribution of PCC energy pile. When the temperatures of circulating water are 70°C, 60°C, 50°C, and 40°C, the result shows that the temperatures of PCC energy pile under different conditions are measured well by the optical fiber sensor. It will help to master the temperature distribution and thermomechanical characteristic of PCC energy pile. It can also provide the important scientific and theoretical basis for the design and application of PCC energy pile. Lei Gao, Baoquan Ji, Gangqiang Kong, Xu Huang, Mingkun Li, and Ali H. Mahfouz Copyright © 2015 Lei Gao et al. All rights reserved. Toward Collinearity-Avoidable Localization for Wireless Sensor Network Mon, 27 Jul 2015 12:48:42 +0000 http://www.hindawi.com/journals/js/2015/908956/ In accordance with the collinearity problem during computation caused by the beacon nodes used for location estimation which are close to be in the same line or same plane, two solutions are proposed in this paper: the geometric analytical localization algorithm based on positioning units and the localization algorithm based on the multivariate analysis method. The geometric analytical localization algorithm based on positioning units analyzes the topology quality of positioning units used to estimate location and provides quantitative criteria based on that; the localization algorithm based on the multivariate analysis method uses the multivariate analysis method to filter and integrate the beacon nodes coordinate matrixes during the process of location estimation. Both methods can avoid low estimation accuracy and instability caused by multicollinearity. Xiaoyong Yan, Aiguo Song, Jimin Yu, and Zhong Yang Copyright © 2015 Xiaoyong Yan et al. All rights reserved. Failure Mechanism of Rock Bridge Based on Acoustic Emission Technique Mon, 27 Jul 2015 12:34:01 +0000 http://www.hindawi.com/journals/js/2015/964730/ Acoustic emission (AE) technique is widely used in various fields as a reliable nondestructive examination technology. Two experimental tests were carried out in a rock mechanics laboratory, which include (1) small scale direct shear tests of rock bridge with different lengths and (2) large scale landslide model with locked section. The relationship of AE event count and record time was analyzed during the tests. The AE source location technology and comparative analysis with its actual failure model were done. It can be found that whether it is small scale test or large scale landslide model test, AE technique accurately located the AE source point, which reflected the failure generation and expansion of internal cracks in rock samples. Large scale landslide model with locked section test showed that rock bridge in rocky slope has typical brittle failure behavior. The two tests based on AE technique well revealed the rock failure mechanism in rocky slope and clarified the cause of high speed and long distance sliding of rocky slope. Guoqing Chen, Yan Zhang, Runqiu Huang, Fan Guo, and Guofeng Zhang Copyright © 2015 Guoqing Chen et al. All rights reserved. A Study on Distribution Measurement and Mechanism of Deformation due to Water Loss of Overburden Layer in Vertical Shaft Mon, 27 Jul 2015 12:33:19 +0000 http://www.hindawi.com/journals/js/2015/531428/ Based on FBG fiber Bragg grating technology and BOTDA distributed optical fiber sensing technology, this study uses fine sand to simulate overburden layer in vertical shaft model equipment. It studies the placing technique and test method for optical fiber sensors in the overburden layer, combined with MODFLOW software to simulate the change of the water head value when the overburden layer is losing water, and obtains the deformation features of overburden layer. The results show, at the beginning of water loss, the vertical deformation increases due to larger hydraulic pressure drop, while the deformation decreases gradually and tends to be stable with the hydraulic pressure drop reducing. The circumferential deformation is closely related to such factors as the distance between each drainage outlet, the variations of water head value, and the method of drainage. The monitoring result based on optical fiber sensing technology is consistent with the characteristics of water loss in overburden layer simulated by MODFLOW software, which shows that the optical fiber sensing technology applied to monitor shaft overburden layer is feasible. Chunde Piao, Jun Yuan, Dangliang Wang, and Pengtao Li Copyright © 2015 Chunde Piao et al. All rights reserved. Deformation Monitoring of Geomechanical Model Test and Its Application in Overall Stability Analysis of a High Arch Dam Mon, 27 Jul 2015 12:22:47 +0000 http://www.hindawi.com/journals/js/2015/470905/ Geomechanical model testing is an important method for studying the overall stability of high arch dams. The main task of a geomechanical model test is deformation monitoring. Currently, many types of deformation instruments are used for deformation monitoring of dam models, which provide valuable information on the deformation characteristics of the prototype dams. However, further investigation is required for assessing the overall stability of high arch dams through analyzing deformation monitoring data. First, a relationship for assessing the stability of dams is established based on the comprehensive model test method. Second, a stability evaluation system is presented based on the deformation monitoring data, together with the relationships between the deformation and overloading coefficient. Finally, the comprehensive model test method is applied to study the overall stability of the Jinping-I high arch dam. A three-dimensional destructive test of the geomechanical model dam is conducted under reinforced foundation conditions. The deformation characteristics and failure mechanisms of the dam abutments and foundation were investigated. The test results indicate that the stability safety factors of the dam abutments and foundation range from 5.2 to 6.0. These research results provide an important scientific insight into the design, construction, and operation stages of this project. Baoquan Yang, Lin Zhang, Enlong Liu, Jianhua Dong, Honghu Zhu, and Yuan Chen Copyright © 2015 Baoquan Yang et al. All rights reserved. Structural Health Monitoring of Wind Turbine Blades: Acoustic Source Localization Using Wireless Sensor Networks Mon, 27 Jul 2015 12:17:47 +0000 http://www.hindawi.com/journals/js/2015/139695/ Structural health monitoring (SHM) is important for reducing the maintenance and operation cost of safety-critical components and systems in offshore wind turbines. This paper proposes an in situ wireless SHM system based on an acoustic emission (AE) technique. By using this technique a number of challenges are introduced due to high sampling rate requirements, limitations in the communication bandwidth, memory space, and power resources. To overcome these challenges, this paper focused on two elements: (1) the use of an in situ wireless SHM technique in conjunction with the utilization of low sampling rates; (2) localization of acoustic sources which could emulate impact damage or audible cracks caused by different objects, such as tools, bird strikes, or strong hail, all of which represent abrupt AE events and could affect the structural health of a monitored wind turbine blade. The localization process is performed using features extracted from aliased AE signals based on a developed constraint localization model. To validate the performance of these elements, the proposed system was tested by testing the localization of the emulated AE sources acquired in the field. Omar Mabrok Bouzid, Gui Yun Tian, Kanapathippillai Cumanan, and David Moore Copyright © 2015 Omar Mabrok Bouzid et al. All rights reserved. Application of Distributed Optical Fiber Sensing Technology in the Anomaly Detection of Shaft Lining in Grouting Mon, 27 Jul 2015 12:06:41 +0000 http://www.hindawi.com/journals/js/2015/678634/ The rupture of the shaft lining caused by grouting has seriously undermined the safety in coal mining. Based on BOTDR distributed optical fiber sensing technology, this paper studied the layout method of optical fiber sensors and the anomaly detection method of the deformation and obtained the evolution law of shaft deformation triggered by grouting. The research results showed that the bonding problem of optical fiber sensors in damp environment could be effectively solved, by applying the binder consisting of sodium silicate and cement. Through BOTDR-based deformation detection, the real-time deformation of the shaft lining caused by grouting was immediately spotted. By comparing the respective strain of shaft lining deformation and concrete deformation, the risk range of shaft lining grouting was identified. With the additional strain increment of the shaft lining triggered by each process of grouting, the saturated condition of grouting volume in strata was analyzed, providing an important technical insight into the field construction and the safety of the shaft lining. Chunde Piao, Jun Yuan, Bin Shi, Haijun Lu, Guangqing Wei, and Chunsheng Gu Copyright © 2015 Chunde Piao et al. All rights reserved. Development and Application of Smart Geogrid Embedded with Fiber Bragg Grating Sensors Mon, 27 Jul 2015 11:23:14 +0000 http://www.hindawi.com/journals/js/2015/108209/ Smart geogrids embedded with fiber Bragg grating (FBG) for reinforcement as well as measurement of geotechnical structures have been developed. After the fabricating process of the geogrids is detailed, finite element (FE) simulations are conducted to analyze the strain distribution of geogrids and the strain transfer characteristics from geogrids to fiber optic. Results indicate that FBG should be deployed in the middle of the geogrids rib to make sure that uniform strain distribution along the FBG. Also, PVC protective sleeves, which are used to protect fiber optic when integrated with geogrids, have smaller strain transfer loss than nylon sleeves. Tensile experiments are conducted to test strain measurement performance of proposed geogrids, and the results demonstrate that proposed smart geogrids have good linearity and consistency. Temperature experiments show that FBG embedded in geogrids has higher temperature sensitivity, and the temperature induced error can be compensated by an extra FBG strain-independent sensor. Furthermore, designed smart geogrids are used in a geotechnical model test to monitor strain during tunnel excavation. The strain tendency measured by smart geogrids and traditional strain sensor agree very well. The results indicate that smart geogrids embedded with FBGs can be an effective method to measure strains for geological engineering related applications. Zheng-fang Wang, Jing Wang, Qing-mei Sui, Xun-mei Liang, Lei Jia, Shu-cai Li, and Shi-de Lu Copyright © 2015 Zheng-fang Wang et al. All rights reserved. Axis-Exchanged Compensation and Gait Parameters Analysis for High Accuracy Indoor Pedestrian Dead Reckoning Mon, 27 Jul 2015 11:07:29 +0000 http://www.hindawi.com/journals/js/2015/915837/ Pedestrian dead reckoning (PDR) is an effective way for navigation coupled with GNSS (Global Navigation Satellite System) or weak GNSS signal environment like indoor scenario. However, indoor location with an accuracy of 1 to 2 meters determined by PDR based on MEMS-IMU is still very challenging. For one thing, heading estimation is an important problem in PDR because of the singularities. For another thing, walking distance estimation is also a critical problem for pedestrian walking with randomness. Based on the above two problems, this paper proposed axis-exchanged compensation and gait parameters analysis algorithm to improve the navigation accuracy. In detail, an axis-exchanged compensation factored quaternion algorithm is put forward first to overcome the singularities in heading estimation without increasing the amount of computation. Besides, real-time heading is updated by R-adaptive Kalman filter. Moreover, gait parameters analysis algorithm can be divided into two steps: cadence detection and step length estimation. Thus, a method of cadence classification and interval symmetry is proposed to detect the cadence accurately. Furthermore, a step length model adjusted by cadence is established for step length estimation. Compared to the traditional PDR navigation, experimental results showed that the error of navigation reduces 32.6%. Honghui Zhang, Jinyi Zhang, Duo Zhou, Wei Wang, Jianyu Li, Feng Ran, and Yuan Ji Copyright © 2015 Honghui Zhang et al. All rights reserved. Study of Three-Component FBG Vibration Sensor for Simultaneous Measurement of Vibration, Temperature, and Verticality Mon, 27 Jul 2015 11:03:34 +0000 http://www.hindawi.com/journals/js/2015/382865/ To achieve simultaneous measurement of measurand vibration, temperature, and verticality, a three-component fiber Brag grating (TVFBG) vibration sensor is proposed in this paper. Polymer and metal diaphragm sensitization methods are utilized to improve this sensor measurement sensitivity. Project matrix theory is adopted to analyze this sensor. Theoretically, nonsingular measuring coefficient matrix of this TVFBG sensor made up by three measurand coefficient matrixes is established. In order to effectively extract measurand, Hilbert-Huang transform (HHT) is accepted to process this sensor’s center wavelength signals. Calibration experiments are carried out to verify the performance of this TVFBG sensor. Experiment data confirm that this sensor has excellent frequency response and show good linearity at temperature and verticality measurement. Wrist rotation angle measurement experiment is also implemented to further identify this sensor practical value. Through analyzing by HHT, experiment results show that the angle measurement sensitivities of three fiber Brag gratings which are included in this sensor are separately 25.2 pm/°, 38.2 pm/°, and 38.3 pm/°. Jiang Shan-chao, Wang Jing, Sui Qing-mei, Ye Qing-lin, and Wang Li-jun Copyright © 2015 Jiang Shan-chao et al. All rights reserved. Application of Method for Dynamic Analysis of Additional Strain and Fracture Warning in Shaft Lining Mon, 27 Jul 2015 10:37:20 +0000 http://www.hindawi.com/journals/js/2015/376498/ In the past few decades, enormous losses have been induced by hundreds of vertical shafts collapse. This study is based on long-term in situ monitoring data of several mines with overburden soil layers in East China in the past six years. modeling based on fractal theory was used to analyze the development of additional strains in shafts by using Hurst exponent. It can be found that from the monitoring results the Hurst effect is significant ranging from 0.5 to 1.0. Its trend also is in good agreement with forward-biased random distribution. Hence, method can be used to predict the additional strain along the shaft lining. In this paper, Hurst exponent shows an irregular phenomenon before cracking. It is proved that Hurst exponent can be used to predicate the progressive failure of shaft lining from abnormal state to normal state. This paper presents the prediction of shaft lining failures using strains measured by embedded strain gauges in the thick overburden soil layers in east China. Guangsi Zhao, Guoqing Zhou, and Jianzhou Wang Copyright © 2015 Guangsi Zhao et al. All rights reserved. Microseismic Signal Characterization and Numerical Simulation of Concrete Beam Subjected to Three-Point Bending Fracture Mon, 27 Jul 2015 10:28:34 +0000 http://www.hindawi.com/journals/js/2015/987232/ To study the generation mechanism and failure mode of cracks in mass concrete, microseismic monitoring is conducted on the fracture processes of the three-point bending roller compacted concrete (RCC) beam of Guanyinyan hydropower station. The spectrum characteristics of microseismic signals in different deformation and failure stages of the concrete beam are analyzed, and the identification method of the fracture stages and crack propagation precursors of concrete beam is established. Meanwhile, the Realistic Failure Process Analysis code (RFPA) is adopted to simulate and analyze the entire failure processes of concrete beam from its cracks initiation, development, propagation, and coalescence, until macroscopic fractures formation subjected to three-point bending test. The relation curve of the load, loaded displacement, and acoustic emission (AE) of concrete beam in the three-point bending test is also obtained. It is found that the failure characteristics of concrete beam obtained from numerical experiments agree well with the field physical test results. The heterogeneity of concrete is the major cause of zigzag propagation paths of beam cracks subjected to three-point bending tests. The results lay foundation for further exploring the formation mechanism of dam concrete cracks of Guanyinyan hydropower station. Nuwen Xu, Feng Dai, Chun Sha, Yingcheng Lei, and Biao Li Copyright © 2015 Nuwen Xu et al. All rights reserved. Blind Source Separation Model of Earth-Rock Junctions in Dike Engineering Based on Distributed Optical Fiber Sensing Technology Mon, 27 Jul 2015 10:06:38 +0000 http://www.hindawi.com/journals/js/2015/281538/ Distributed temperature sensing (DTS) provides an important technology support for the earth-rock junctions of dike projects (ERJD), which are binding sites between culvert, gates, and pipes and dike body and dike foundation. In this study, a blind source separation model is used for the identification of leakages based on the temperature data of DTS in leakage monitoring of ERJD. First, a denoising method is established based on the temperature monitoring data of distributed optical fiber in ERJD by a wavelet packet signal decomposition technique. The temperature monitoring messages of fibers are combined response for leakages and other factors. Its character of unclear responding mechanism is very obvious. Thus, a blind source separation technology is finally selected. Then, the rule of temperature measurement data for optical fiber is analyzed and its temporal and spatial change process is also discussed. The realization method of the blind source separation model is explored by combining independent component analysis (ICA) with principal component analysis (PCA). The practical test result in an example shows that the method could efficiently locate and identify the leakage location of ERJD. This paper is expected to be useful for further scientific research and efficient applications of distributed optical fiber sensing technology. Huaizhi Su, Meng Yang, Kunpeng Zhao, and Zhiping Wen Copyright © 2015 Huaizhi Su et al. All rights reserved. A Practical Method for Grid Structures Damage Location Mon, 27 Jul 2015 09:59:06 +0000 http://www.hindawi.com/journals/js/2015/246480/ A damage location method based on cross correlation function, wavelet packet decomposition, and support vector machine was proposed for grid structure. The approximate damage positions in grid structures could be determined through the peak abrupt changes of the cross correlation function that was produced by two vibration responses of adjacent measuring points. The vibration response was decomposed into eight bands by wavelet packet in order to accurately locate damage rods. The energy distribution in eight bands was used as a feature vector. SVM is trained to locate damaged bar elements in grid structures. Numerical analysis results showed that this method had good accuracy. Zhefu Yu and Linsheng Huo Copyright © 2015 Zhefu Yu and Linsheng Huo. All rights reserved. Superresolution Polarimetric ISAR Imaging Based on 2D CP-GTD Model Mon, 27 Jul 2015 07:39:04 +0000 http://www.hindawi.com/journals/js/2015/293141/ This paper presented a new approach to superresolution ISAR imaging based on a scattering model called coherent polarized geometrical theory of diffraction (CP-GTD) which is better matched to the physical scattering mechanism. The algorithm is a joint processing between polarization and superresolution essentially. It can also estimate the number, position, frequency dependence, span, and normalized scattering matrix of scattering centers instantaneously for each channel rather than the one which extracts parameters from each channel separately, and its performance is better than the latter because the fully polarized information is used. The superiority of the CP-GTD is verified by experiment results based on simulated and real data. Da-hai Dai, Jing-ke Zhang, Xue-song Wang, and Shun-ping Xiao Copyright © 2015 Da-hai Dai et al. All rights reserved. Impact of Topography and Tidal Height on ALOS PALSAR Polarimetric Measurements to Estimate Aboveground Biomass of Mangrove Forest in Indonesia Mon, 27 Jul 2015 07:01:06 +0000 http://www.hindawi.com/journals/js/2015/641798/ This study is focused on investigating the impact of topography and tidal height on ALOS PALSAR polarimetric measurements on HH and HV for estimating aboveground biomass (AGB) of mangrove forest in Indonesia. We used multitemporal ALOS PALSAR polarimetric measurement that covered mangrove zone in Banyuasin, Cilacap, and Teluk Bintuni and also collected tidal height data within the same acquisition date with multitemporal ALOS PALSAR polarimetric measurement. We analyzed the distribution of flooding and nonflooding areas based on tidal height and SRTM topography data, created three profiles as region of interest (ROI), and got characteristics of backscatter value on HH and HV with different tidal height. The result of this study showed backscatter of the open mangrove zones during high tide with HH value less than −20 dB and HV value less than −25 dB whereas during low tide it showed an HH value around −20 to −10 dB and HV value around −25 to −10 dB. Backscatter of the middle mangrove zones at Cilacap, with low and flat topography, showed a deviation of backscatter on HV value of 1.6 dB. Finally, the average AGB of mangrove forest in Indonesia was estimated based on ALOS PALSAR polarimetric measurements. S. Darmawan, W. Takeuchi, Y. Vetrita, K. Wikantika, and D. K. Sari Copyright © 2015 S. Darmawan et al. All rights reserved. Block Design-Based Asynchronous Neighbor Discovery Protocol for Wireless Sensor Networks Sun, 26 Jul 2015 11:56:00 +0000 http://www.hindawi.com/journals/js/2015/951652/ Neighbor discovery is a significant research topic in wireless sensor networks. After wireless sensor devices are deployed in specific areas, they attempt to determine neighbors within their communication range. This paper proposes a new Block design-based Asynchronous Neighbor Discovery protocol for sensor networks called BAND. We borrow the concept of combinatorial block designs for neighbor discovery. First, we summarize a practical challenge and difficulty of using the original block designs. To address this challenge, we create a new block generation technique for neighbor discovery schedules and provide a mathematical proof of the proposed concept. A key aspect of the proposed protocol is that it combines two block designs in order to construct a new block for neighbor discovery. We analyze the worst-case neighbor discovery latency numerically between our protocol and some well-known protocols in the literature. Our protocol reveals that the worst-case latency is much lower than others. Finally, we evaluate the performance of BAND and existing representative protocols through the simulation study. The results of our simulation study show that the average and maximum latency of BAND is about 40% lower than that of existing protocols. Furthermore, BAND spends approximately 30% less energy than others during the neighbor discovery process. Sangil Choi, Wooksik Lee, Teukseob Song, and Jong-Hoon Youn Copyright © 2015 Sangil Choi et al. All rights reserved. Detecting the Depth of a Subsurface Brine Layer in Lop Nur Lake Basin Using Polarimetric L-Band SAR Sun, 26 Jul 2015 11:32:12 +0000 http://www.hindawi.com/journals/js/2015/245790/ Lop Nur once was a huge lake located in northwestern China. At present, there is no surface water in Lop Nur Lake basin and on SAR images it looks like an “Ear.” The objective of this paper is to retrieve the depth of subsurface brine layer in Lop Nur by copolarized phase difference of surface scattering. Based on field investigation and analysis of sample properties, a two-layer scattering structure was proposed with detailed explanations of scattering mechanisms. The relationship between copolarized phase difference and the brine layer depth in the region of Lop Nur were studied. The copolarized phase difference of surface scattering was extracted by model-based polarimetric decomposition method. A good linear correlation between measured subsurface brine layer depth and copolarized phase difference with R2 reaching 0.82 was found. Furthermore, the subsurface brine layer depth of the entire lake area was analyzed. According to the retrieved maps, some interesting phenomena were found, and several hypotheses about the past water withdrawal process and the environmental evolution had been proposed to theoretically explain these phenomena. Based on the penetration capability of SAR the reconstruction of historical evolution process of Lop Nur will be an interesting topic for future research. Chang-An Liu, Huaze Gong, Yun Shao, and Bingyan Li Copyright © 2015 Chang-An Liu et al. All rights reserved. Model-Based Pseudo-Quad-Pol Reconstruction from Compact Polarimetry and Its Application to Oil-Spill Observation Sun, 26 Jul 2015 08:29:26 +0000 http://www.hindawi.com/journals/js/2015/734848/ Compact polarimetry is an effective imaging mode for wide area observation, especially for the open ocean. In this study, we propose a new method for pseudo-quad-polarization reconstruction from compact polarimetry based on the three-component decomposition. By using the decomposed powers, the reconstruction model is established as a power-weighted model. Further, the phase of the copolarized correlation is taken into consideration. The phase of double-bounce scattering is closer to π than to 0, while the phase of surface scattering is closer to 0 than to π. By considering the negative (double-bounce reflection) and positive (surface reflection) copolarized correlation, the reconstruction model for full polarimetry has a good consistency with the real polarimetric SAR data. -band ALOS/PALSAR-1 fully polarimetric data acquired on August 27, 2006, over an oil-spill area are used for demonstration. Reconstruction performance is evaluated with a set of typical polarimetric oil-spill indicators. Quantitative comparison is given. Results show that the proposed model-based method is of great potential for oil-spill observation. Junjun Yin, Wooil Moon, and Jian Yang Copyright © 2015 Junjun Yin et al. All rights reserved. Monitoring of Damage in Sunflower and Maize Parcels Using Radar and Optical Time Series Data Sun, 26 Jul 2015 08:06:24 +0000 http://www.hindawi.com/journals/js/2015/548506/ The objective of this paper is to monitor the temporal behaviour of geometrical structural change of cropland affected by four different types of damage: weed infection, Western Corn Rootworm (WCR), storm damage, and drought by time series of different type of optical and quad-pol RADARSAT2 data. Based on our results it is established that ragweed infection in sunflower can be well identified by evaluation of radar (mid-June) and optical (mid-August) satellite images. Effect of drought in sunflower is well recognizable by spectral indices derived from optical as well as “”-component of Shannon entropy () from radar satellite images acquired during the first decade of July. Evaluation of radar and optical satellite images acquired between the last decade of July and mid-August proven to be the most efficient for detecting damages in maize fields caused by either by WCR or storm. Components of Shannon entropy are proven to have significant role in identification. Our project demonstrates the potential in integrated usage of polarimetric radar and optical satellite images for monitoring several types of agricultural damage. György Surek and Gizella Nádor Copyright © 2015 György Surek and Gizella Nádor. All rights reserved. Comparisons of Circular Transmit and Linear Receive Compact Polarimetric SAR Features for Oil Slicks Discrimination Sun, 26 Jul 2015 07:53:36 +0000 http://www.hindawi.com/journals/js/2015/631561/ Compact polarimetric (CP) synthetic aperture radar (SAR) has proven its potential in distinguishing oil slicks and look-alikes. Polarimetric information can be retrieved directly from scattering vector or from reconstructed pseudo-Quad-Pol covariance matrix of CP SAR data. In this paper, we analysed features from Circular Transmit and Linear Receive (CTLR) CP SAR data that are derived by taking both of these two methods. K-means clustering followed by accuracy assessment was also implemented for performance evaluation. Through experiments that were conducted based on L-band UAVSAR fully polarimetric data, it was found that optimum extraction methods varied for different features. The histogram analysis and segmentation results also demonstrated the comparable performance of CP SAR features in distinguishing different damping properties within oil slicks. This study proposed a framework of statistically analyzing polarimetric SAR (Pol-SAR) features and provided guidelines for determining optimum feature extraction methods from CP SAR data and for marine oil-spills detection and classification. Yu Li, Hui Lin, Yuanzhi Zhang, and Jie Chen Copyright © 2015 Yu Li et al. All rights reserved. Adaptive Sensing with Reliable Guarantee under White Gaussian Noise Channels of Sensor Networks Wed, 15 Jul 2015 10:28:10 +0000 http://www.hindawi.com/journals/js/2015/532045/ Quality of sensing is a fundamental research topic in sensor networks. In this paper, we propose an adaptive sensing technique to guarantee the end-to-end reliability while maximizing the lifetime of sensor networks under additive white Gaussian noise channels. First, we conduct theoretical analysis to obtain optimal node number , node placement , and node transmission structure under minimum total energy consumption and minimum unit data transmission energy consumption. Then, because sensor nodes closer to the sink consume more energy, nodes far from the sink have more residual energy. Based on this observation, we propose an adaptive sensing technique to achieve balanced network energy consumption. It adopts lower reliability requirement and shorter transmission distance for nodes near the sink and adopts higher reliability requirement and farther transmission distance for nodes far from the sink. Theoretical analysis and experimental results show that our design can improve the network lifetime by several times (1–5 times) and network utility by 20% and the desired reliability level is also guaranteed. Jun Long, An He, Anfeng Liu, and Xue Chen Copyright © 2015 Jun Long et al. All rights reserved. The Reduction of Modal Sensor Channels through a Pareto Chart Methodology Tue, 14 Jul 2015 12:34:48 +0000 http://www.hindawi.com/journals/js/2015/869258/ Presented herein is a new experimental sensor placement procedure developed to assist in placing sensors in key locations in an efficient method to reduce the number of channels for a full modal analysis. It is a fast, noncontact method that uses a laser vibrometer to gather a candidate set of sensor locations. These locations are then evaluated using a Pareto chart to obtain a reduced set of sensor locations that still captures the motion of the structure. The Pareto chart is employed to identify the points on a structure that have the largest reaction to an input excitation and thus reduce the number of channels while capturing the most significant data. This method enhances the correct and efficient placement of sensors which is crucial in modal testing. Previously this required the development and/or use of a complicated model or set of equations. This new technique is applied in a case study on a small unmanned aerial system. The test procedure is presented and the results are discussed. Kaci J. Lemler and William H. Semke Copyright © 2015 Kaci J. Lemler and William H. Semke. All rights reserved. Recent Advances of Amorphous Wire CMOS IC Magneto-Impedance Sensors: Innovative High-Performance Micromagnetic Sensor Chip Tue, 14 Jul 2015 09:56:41 +0000 http://www.hindawi.com/journals/js/2015/718069/ We analyzed and organized the reasons why the amorphous wire CMOS IC magneto-impedance sensor (MI sensor) has rapidly been mass-produced as the electronic compass chips for the smart phones, mobile phones, and the wrist watches. Comprehensive advantageous features regarding six terms of (1) microsizing and ultralow power consumption, (2) high linearity without any hysteresis for the magnetic field detection, (3) high sensitivity for magnetic field detection with a Pico-Tesla resolution, (4) quick response for detection of magnetic field, (5) high temperature stability, and (6) high reversibility against large disturbance magnetic field shock are based on the magneto-impedance effect in the amorphous wires. We have detected the biomagnetic field using the Pico-Tesla resolution MI sensor at the room temperature such as the magneto-cardiogram (MCG), the magneto-encephalogram (MEG), and the self-oscillatory magnetic field of guinea-pig stomach smooth muscles (in vitro) that suggest the origin of the biomagnetic field is probably pulsive flow of Ca2+ through the muscle cell membrane. Kaneo Mohri, Tsuyoshi Uchiyama, Larissa V. Panina, Michiharu Yamamoto, and Kenichi Bushida Copyright © 2015 Kaneo Mohri et al. All rights reserved. Image Quality Assessment of a CMOS/Gd2O2S:Pr,Ce,F X-Ray Sensor Mon, 13 Jul 2015 11:34:33 +0000 http://www.hindawi.com/journals/js/2015/874637/ The aim of the present study was to examine the image quality performance of a CMOS digital imaging optical sensor coupled to custom made gadolinium oxysulfide powder scintillators, doped with praseodymium, cerium, and fluorine (Gd2O2S:Pr,Ce,F). The screens, with coating thicknesses 35.7 and 71.2 mg/cm2, were prepared in our laboratory from Gd2O2S:Pr,Ce,F powder (Phosphor Technology, Ltd.) by sedimentation on silica substrates and were placed in direct contact with the optical sensor. Image quality was determined through single index (information capacity, IC) and spatial frequency dependent parameters, by assessing the Modulation Transfer Function (MTF) and the Normalized Noise Power Spectrum (NNPS). The MTF was measured using the slanted-edge method. The CMOS sensor/Gd2O2S:Pr,Ce,F screens combinations were irradiated under the RQA-5 (IEC 62220-1) beam quality. The detector response function was linear for the exposure range under investigation. Under the general radiography conditions, both Gd2O2S:Pr,Ce,F screen/CMOS combinations exhibited moderate imaging properties, in terms of IC, with previously published scintillators, such as CsI:Tl, Gd2O2S:Tb, and Gd2O2S:Eu. Christos Michail Copyright © 2015 Christos Michail. All rights reserved.