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Table of Content

    20 June 2015 Volume 42 Issue 3
      
    Original Articles
    Depth map intra coding based on correlation between video and depth maps
    MA Xiang;HUO Junyan;REN Guangliang;YANG Xu;CHANG Yilin
    J4. 2015, 42(3):  1-7.  doi:10.3969/j.issn.1001-2400.2015.03.001
    Abstract ( 693 )   PDF (1580KB) ( 944 )   Save
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    Since the coding efficiency of the depth macro-block (MB) that contains the edge by using the existing intra coding method is low,an edge skip intra coding method based on the correlation between video and depth maps is proposed.In this method,the segmentation information of the current depth MB and its reference samples is derived from the corresponding video regions by clustering.With the segmentation information,the reference samples are mapped to the current MB as predicted samples.In order to remove the disturbance to the segmentation information caused by the noise point and burr from the clustering operation,a refinement operation is proposed by bi-direction scanning.With the proposed method,the complex edge of an edge MB,even a total edge MB,is skipped without coding.Experimental results demonstrate that compared with the original coding algorithm,the proposed method can reduce the coding bit-rate by 24.25% and increase the peak signal-to-noise ratio (PSNR) by 0.70dB on average.Besides,the subjective coding quality is also improved obviously.

    Algorithm to detect Android malicious behaviors
    WANG Zhiqiang;ZHANG Yuqing;LIU Qixu;HUANG Tingpei
    J4. 2015, 42(3):  8-14.  doi:10.3969/j.issn.1001-2400.2015.03.002
    Abstract ( 888 )   PDF (986KB) ( 1707 )   Save
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    The paper presents a novel Android malware behavioral detection algorithm. The algorithm characterizes Android applications’ behaviors by system call sequences and control flow sequences, trains a malware feature base and a threshold by analyzing known malware samples. Then, we calculate the similarities between the feature base and Android applications, and detect malware by comparing the similarities with the threshold. Finally, an Android malware detection system named SCADect is developed according to the algorithm. The detection accuracy of detecting 3000 samples is up to 96.8%, and the detection rate of classifying 8-cluster obfuscated malware including 237 samples can reach 89%, obviously better than the tool Androguard. The results show that the SCADect is able to resist obfuscated and cryptographic attacks, improves the detection accuracy and reduces the false negative rate.

    Novel method for attributed feature extraction from SAR imagery
    LI Fei;JIU Bo;WANG Yinghua;LUO Tao;LIU Hongwei
    J4. 2015, 42(3):  15-21+89.  doi:10.3969/j.issn.1001-2400.2015.03.003
    Abstract ( 763 )   PDF (937KB) ( 648 )   Save
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    Aiming to extract attributed features of overlapped attributed scattering centers, a new method for attributed feature extraction of the SAR target is proposed based on the fully polarimetric attributed scattering center model by considering the sparsity of the scattering center in the space domain and scattering mechanism domain. According to this sparsity, the row sparse constraint and matrix sparse constraint are imposed on the polarimetric decomposition coefficient matrix of the target, respectively. Since the polarimetric scattering mechanism dictionary contains an unknown parameter, the coordinate decent technique is employed to optimize the polarimetric decomposition coefficient matrix and polarimetric scattering mechanism dictionary for attributed feature extraction (attributed scattering center and polarimetric signature). Numerical results on electromagnetic computation data verify the validity of the proposed algorithm.

    TOA localization algorithm using the linear-correction technique
    ZHU Guohui;FENG Dazheng;ZHOU Yan;NIE Weike
    J4. 2015, 42(3):  22-25+32.  doi:10.3969/j.issn.1001-2400.2015.03.004
    Abstract ( 626 )   PDF (437KB) ( 1013 )   Save
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    A new time of arrival (TOA) location algorithm based on the linear correction technique is proposed to address the non-linear problem of TOA positioning. The proposed algorithm firstly rearranges the TOA measurement equations into pseudo-linear ones and we obtain the initial target position estimation using the weighted least-squares estimator. Then a linear correction technique is used to correct the initial estimation. The effectiveness of the proposed method is analyzed. Simulation study validates the good performance of the proposed algorithm.

    Three dimensional space-time open-loop clutter block canceller applied to the airborne phased array radar
    XIANG Pingye;FENG Dazheng;ZHOU Yan;ZHU Guohui
    J4. 2015, 42(3):  26-32.  doi:10.3969/j.issn.1001-2400.2015.03.005
    Abstract ( 549 )   PDF (895KB) ( 521 )   Save
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    Aiming at the excessive clutte's DOFs (degrees of freedom) and huge demand for training samples of 3D-STAP,a three  dimensional  space- time open-loop  clutter  block  canceller (3D-STCBC) is proposed. First, the vector-matrix model of the three dimensional clutter is constructed with the a priori knowledge. Then the equivalence between the spatial domain and the temporal domain is exploited to design a coefficient matrix to make a cancellation between the clutter blocks. The experiment shows that this method can effectively suppress the clutter even with small samples and dramatically lower the clutter's DOFs.

    Design of a plane-wave generator for base station antenna measurements
    FENG Xueyong;YANG Lin;GONG Shuxi;WANG Jianxiao
    J4. 2015, 42(3):  33-37.  doi:10.3969/j.issn.1001-2400.2015.03.006
    Abstract ( 560 )   PDF (939KB) ( 543 )   Save
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    Genetic Algorithm (GA)is applied to the design of an S-band plane wave generator(PWG). This PWG is a line array with 25 elements, which can generate a quiet zone with the size of 0.96m×0.18m×0.96m at the 26 to 34 wavelengths distance away from the array. The amplitude variation of this quiet zone at each section is less than 1dB, and the phase variation is less than 10 °. The work frequency range can reach 2.2~2.8GHz.This PWG can be used for time division long term evolution(TD-LTE) base station antenna measurements, with the chamber size effectively reduced and the test accuracy of AUT improved by the use of this PWG.

    Design of a novel multiple-mode tri-band bandpass filter
    LIN Lei;SUN Shoujia;WU Bian;LIANG Changhong
    J4. 2015, 42(3):  38-42+96.  doi:10.3969/j.issn.1001-2400.2015.03.007
    Abstract ( 620 )   PDF (1222KB) ( 946 )   Save
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    A compact tri-band microstrip filter based on an MMR (multiple mode resonator) is presented, which consists of an MMR and a pair of feedlines. Firstly, due to the symmetry of the structure, the even-odd-mode method is applied twice to analysis the resonant characteristics. All the six mode frequencies can be freely tuned by changing the lengths of loaded stubs, and all the four modes equivalent circuits are quarter-wavelength resonators, which largely minimize the size of the filter. Secondly, stub to stub coupling is introduced to split two modes and produce two new transmission zeros with the passband selectivity improved. Finally, a microstrip tri-band bandpass filter (BPF) operating at 1.5GHz/2.4GHz/3.5GHz is designed, fabricated and measured. Measured results are in good agreement with the simulated ones.

    Study of the parallel higher-order MoM on a domestically-made CPU platform
    LIN Zhongchao;CHEN Yan;ZHANG Yu;JIANG Shugang;ZHAO Xunwang;L Zhaofeng
    J4. 2015, 42(3):  43-47.  doi:10.3969/j.issn.1001-2400.2015.03.008
    Abstract ( 786 )   PDF (1805KB) ( 697 )   Save
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    The parallel higher-order method of moments is firstly utilized to simulate electromagnetic radiation and scattering problems on a domestically-made supercomputing platform with its parallel efficiency tested. Higher-order polynomials over wires and quadrilateral plates, which can ensure accuracy, are used as basic functions over larger subdomain patches to reduce the number of unknowns. The parallel strategies based on block matrices can improve the computational scale and simulation speed. Numerical results show that the self-developed procedures provide an effective way to solve complex electromagnetic problems on the supercomputing platform.

    Combined similarity based spectral clustering ensemble for POLSAR classification
    LIU Lu;WANG Rongfang;JIAO Licheng;SHI Junfei
    J4. 2015, 42(3):  48-53+128.  doi:10.3969/j.issn.1001-2400.2015.03.009
    Abstract ( 633 )   PDF (4319KB) ( 536 )   Save
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    In order to improve the robustness of spectral clustering to the scaling parameter and avoid the instable results caused by the Nystrm approximation, a novel spectral clustering ensemble method for Polarimetric SAR (PolSAR) land cover classification is proposed. Firstly, Wishart-derived distance measure and polarimetric similarity are combined to obtain the complementary information from the spatial and polarimetric relations between pairwise pixels. The Markov Random Field (MRF) potential function is introduced to construct the similarity matrix. Then the Nystrm approximation based spectral clustering is employed to achieve a single spectral classification of PolSAR data. Finally, multiple individual classifications are obtained and integrated by an ensemble strategy. Experimental results demonstrate that the proposed method improves the classification performance and region harmony, and leads to stable results.

    Voltage triggered ESD detection circuits in a 90nm CMOS process
    YANG Zhaonian;LIU Hongxia;ZHU Jia;FEI Chenxi
    J4. 2015, 42(3):  54-60.  doi:10.3969/j.issn.1001-2400.2015.03.010
    Abstract ( 737 )   PDF (737KB) ( 549 )   Save
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    Two voltage triggered electrostatic discharge (ESD) detection circuits are proposed in a 90nm 1V CMOS process, which can avoid the gate leakage current issue in the nanometer CMOS process. The proposed circuits include feedback loops to enhance the ESD trigger efficiency, and also add turn-off mechanisms, which can turn off the feedback when they are turned on for some unknown reasons and cannot be latched on. Under 3V ESD simulation, the circuits can inject 28mA trigger currents into the clamp device. Under the 25℃ normal operating condition the leakage current is 42nA and 45nA , respectively. Simulation result shows that the circuits can be successfully used in nanometer CMOS process ESD protection.

    Online visual tracking method based on superpixel hybrid voting
    HE Wenhua;LIU Zhijing;QU Jianming
    J4. 2015, 42(3):  61-66.  doi:10.3969/j.issn.1001-2400.2015.03.011
    Abstract ( 613 )   PDF (4455KB) ( 490 )   Save
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    It is a great challenge to track an object robustly when variations occur such as changes in illumination, appearance or partial occlusion. In this paper, we propose a target tracking algorithm combining superpixel and hybrid Hough voting. Local features are extracted from the context as supporters to construct a hybrid voting model. By this model, the target center is estimated by the Hough voting scheme. Local features are also distinguished to vote for the target and background, respectively. These voting results are combined into superpixels. Finally, the tracking task is formulated as the maximum a posterior estimate in the voting space. We demonstrate the performance of the algorithm on several public video sequences, which shows that our method is better than other online tracking approaches.

    Directed AdaBoost weighting classifier based on the scene motion pattern for object detection
    QU Jianming;LIU Zhijing;HE Wenhua
    J4. 2015, 42(3):  67-72.  doi:10.3969/j.issn.1001-2400.2015.03.012
    Abstract ( 610 )   PDF (3610KB) ( 475 )   Save
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    The regular behavior reflected by the interaction of spatial layout and interior elements of the scene with the moving object is named the scene motion pattern. In this paper, a novel approach of the object detection combining scene motion pattern with the directed AdaBoost weighting method is proposed to remedy the limitation of the existing detection algorithms that give little consideration of the object motion regularity and the priori information about the scene. For this reason, a model of the scene motion pattern described by a matrix of speed-weighting directed histogram is created, and the information about the scene motion pattern is acquired by the voting of the sparse optical flows on that basis. Meanwhile, a directed AdaBoost weighting detection algorithm is developed correspondingly. A set of directed AdaBoost classifiers which are then weighted according to the motion pattern of the region are established in the algorithm. According to the specially designed cross-validation classification experiments and video tests, the precision rates of the algorithm are about 10% higher than that of standard AdaBoost detector under the same condition of the false positive rate, which proves the effectiveness and the advancements of the proposed approach.

    Laser radar imaging model for high-fidelity simulation and its analysis
    CHAI Guobei;ZHANG Jianqi;LIU Delian;TIAN Limin;GUO Bingtao
    J4. 2015, 42(3):  73-77.  doi:10.3969/j.issn.1001-2400.2015.03.013
    Abstract ( 656 )   PDF (1101KB) ( 939 )   Save
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    In order to improve the fidelity of laser imaging simulation, the ray tracing method is used to construct a laser radar system which can get the synthetic laser radar images of 3D scenes. By using the laser scattering law, the illumination model widely used in computer graphic is modeled into a laser radar imaging model for high-fidelity simulation. The improvements of the model are follows: ①adding the direct reflection term, ②changing the multiple light source model in luminance into the multiple reflection model in power, and ③introducing the detector noise into the model. Laser radar images are calculated for a typical 3D scene. A comparison of the calculated results with the real laser radar images is made, which shows that the calculated result is similar to the one received by the laser radar system. And quantitative analysis shows that there also exists a difference, with the reasons are analyzed.

    Collision of two solitons with the same envelope  in the left-handed materials
    YANG Dongqi;ZHANG Jianqi
    J4. 2015, 42(3):  78-82.  doi:10.3969/j.issn.1001-2400.2015.03.014
    Abstract ( 512 )   PDF (868KB) ( 509 )   Save
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    For the soliton solution of coupled nonlinear Schrodinger equations, their collision behavior in the nonlinear left-handed materials is important for the propagation research on this kind of solitons. In this paper, we employ the Split-Step Fourier Method (SSFM) to simulate the collision process of two solitons with the same envelope. Simulation shows that the two solitons with the same envelope can keep their properties unchanged in the collision, such as their shape and velocity. By neglecting the loss, after the collision, the two solitons continue to propagate without loss of their own initial state and properties in the nonlinear left-handed materials. These results provide the knowledge of the propagation and collision of solitions which is the soliton solution of the coupled nonlinear Schrdinger equations in the nonlinear left-handed materials.

    Algorithm improvement of directional location management
    CHEN Jie;XI Wen;MO Wei
    J4. 2015, 42(3):  83-89.  doi:10.3969/j.issn.1001-2400.2015.03.015
    Abstract ( 504 )   PDF (759KB) ( 516 )   Save
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    In order to accurately calculate the cost of location management for the wireless cellular network, this paper puts forwards the predictive directional Markov chain as a mobility model based on the two-dimensional hexagon cellular structures. According to the location update model based on the two-steps paging strategy established between two consecutive arrival calls to get the optimal threshold of movement-based location management and the probability distribution of crossing the cell boundary K times on the condition that the incoming calls form a Poisson process and the MT's cell residence time has exponential probability distribution. Then with these given probability distribution we give the optimal two-steps paging strategy. Finally, numerical results show that this strategy outperforms some well-known basic paging schemes.

    Novel sensor node importance evaluation method based on the agglomeration contraction principle
    LIU Kui;LIU Sanyang
    J4. 2015, 42(3):  90-96.  doi:10.3969/j.issn.1001-2400.2015.03.016
    Abstract ( 587 )   PDF (704KB) ( 664 )   Save
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    Node importance evaluation based on removal of nodes and their incident links cannot accurately reflect the importance of the nodes. Because this way may change the topology of wireless sensor networks, and even splits the network into several disconnected parts. To solve this question, we propose a novel node importance evaluation method based on the agglomeration contraction principle. This method does not need to remove the assessment node from the network, and thus this method may not cause the network to be fractured. In this method, with the help of a spectral method, the vital gateway nodes can be obtained by using the nontrivial eigenvectors of the Laplace matrix of the network diagram firstly. After that, by using some super-energy nodes to provide targeted protection for vital gateway nodes in a wireless sensor network, this way can prolong the life of the network and improve the robustness of the system effectively. Above all, this method can reduce the number of evaluation nodes in a wireless sensor network, and decrease the workload of calculation accordingly. Final examples verify its efficiency and the result is consistent with our intuitive judgments.

    Efficient attribute-based encryption with hidden access structures
    XIE Li;REN Yanli
    J4. 2015, 42(3):  97-102.  doi:10.3969/j.issn.1001-2400.2015.03.017
    Abstract ( 622 )   PDF (449KB) ( 622 )   Save
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    Currently, Attribute-Based Encryption (ABE) schemes with Hidden Access Structures are proposed in groups of a composite order or only proved selectively secure without random oracles. Using asymmetric pairings, an anonymous ciphertext-policy attribute-based encryption scheme is proposed in a prime order bilinear group in this paper. The scheme is proved fully secure under the standard model based on the asymmetric decisional bilinear Diffie-Hellman (DBDH) assumption. Moreover, it has a constant size private key, a ciphertext and the number of pairing operations. The proposed scheme improves the security and efficiency of ABE schemes with hidden access structures when compared with the ones in groups of a composite order.

    Performance research on ranging codes based on  the chaotic sequence
    XUE Rui;WEI Qiang;XU Xichao
    J4. 2015, 42(3):  103-108.  doi:10.3969/j.issn.1001-2400.2015.03.018
    Abstract ( 552 )   PDF (553KB) ( 598 )   Save
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    Since the chaotic sequence has a lot of numbers, good relative performance, strong security, high security and approaching statistical properties of Gaussian white noise, a ranging code based on the weighted optimizing chaotic sequence is proposed. This code is obtained by two different initial improved Logistic chaotic sequences through weighting and summation and quantification. This paper analyses various classic chaotic sequences including the weighted optimizing chaotic sequence as the performance of the ranging code based on the peaks of autocorrelation and crosscorrelation, and the Welch bound. Theoretical analysis and simulation results show that the ranging code based on the improved Logistic chaotic sequence greatly improves the balance and that the ranging code performance is good and at the same time enhances the security and privacy of the ranging code.

    Dual loop Volterra filter predistortion in satellite communication
    TANG Chengkai;LIAN Baowang;ZHANG Lingling
    J4. 2015, 42(3):  109-114.  doi:10.3969/j.issn.1001-2400.2015.03.019
    Abstract ( 630 )   PDF (661KB) ( 513 )   Save
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    Aimed at the non-linear output signal of the satellite carryon amplifier, a simplified predistortion algorithm is proposed. The algorithm is implemented by two one-order truncated Volterra filter models to construct the forward and feedback loop, and we adjust the predistortion coefficients with this dual loop to linear the output of the satellite transmitted signal. With this simplied predistortion algorithm, the predistortion coefficients updating speed and accuracy could be increased, and the linear characteristic for the signal transmitted by the satellite is well guaranteed.

    Face recognition using collaborative representation with neighbors
    WEI Dongmei;ZHOU Weidong
    J4. 2015, 42(3):  115-121.  doi:10.3969/j.issn.1001-2400.2015.03.020
    Abstract ( 516 )   PDF (1520KB) ( 648 )   Save
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    An improved face recognition algorithm using the collaborative representation with nearer neighbors of the testing image is proposed. As a measurement to find the neighboring testing sample,the correlation coefficient between the testing sample and training samples is calculated in the Gabor-feature space. Neighbors of the testing sample compose the compact over-completed dictionary which is variable for different testing samples. The testing image is represented collaboratively by the variable "thickness" compact dictionary and the sparse representation coefficient is calculated with l<sub>2</sub> minimization. The error between the reconstructed image and the testing image categorizes the testing image. This proposed algorithm has been carried out in database of FERET, ORL and AR with variations of lighting, expression, pose, and occlusion. Extensive experiments demonstrate that the proposed approach is superior both in recognition rate and in speed.

    Algorithm for conformal array DOA estimation with an unknown number of sources
    YANG Qun;CAO Xiangyu;GAO Jun;LI Sijia
    J4. 2015, 42(3):  122-128.  doi:10.3969/j.issn.1001-2400.2015.03.021
    Abstract ( 506 )   PDF (591KB) ( 679 )   Save
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    An algorithm for conformal array DOA estimation with an unknown number of sources is developed to solve the problem that most of the DOA algorithms are based on the prior knowledge of the number of sources and the estimation error of the number of sources leads to the degradation of DOA algorithm performance. This method is realized by introducing the pseudo expected signal. Firstly, the received narrow band signal of the conformal array is modeled and the adaptive beamforming theory is introduced. The optimum weight deduced by the Maximum signal to inference and noise ratio (SINR) is applied to the received signal and the pseudo expected signal and the conformal array output signal to noise ratio (SNR) is regarded as the parameter of the DOA to accomplish the estimation. During the processing, the proposed method does not need the prior knowledge of the number of sources and the signal number estimation is avoided. Finally the validity of the algorithm is verified by simulation experiments. The simulation results show that the algorithm is effective and superior to the MUSIC (multiple signal classification) algorithm.

    FH signal extraction using the improved symmetric  co-occurrence matrix
    GU Pei;WANG Bin
    J4. 2015, 42(3):  129-134.  doi:10.3969/j.issn.1001-2400.2015.03.022
    Abstract ( 476 )   PDF (1572KB) ( 493 )   Save
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    Aiming at the problem of removing the background noise and fixed-frequency interference in the blind detection of FH signals from the HF channel, this paper proposes an FH signals extraction algorithm based on the noise-sparse symmetric co-occurrence matrix. Firstly, we define the noise-sparse symmetric co-occurrence matrix in the direction of frequency and time to improve the calculation of the co-occurrence matrix. Secondly, we estimate the noise threshold based on the frequency-sparse symmetric co-occurrence matrix and then extract the FH signals from the time-sparse co-occurrence matrix with the threshold. Simulation results show that the algorithm can realize the blind extraction of the FH signal on the condition of a low SNR. Estimation of the threshold in background noise is more accurate and stable. The performance of FH signal extraction is better and algorithm is simple with less computation and is easy to apply in engineering.

    Implementation and optimization of the wideband matched filter on the GPU
    ZHOU Hang;CAI Zhiming;WANG Ximin
    J4. 2015, 42(3):  135-140+191.  doi:10.3969/j.issn.1001-2400.2015.03.023
    Abstract ( 657 )   PDF (680KB) ( 626 )   Save
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    The fine estimation of wideband ambiguity, which has a sharp main ridge, requires large amounts of searching on the time-scale. That desperately needs the well-optimized software on high performance hardware. In terms of wideband correlation, the matched filter based on the CWT and its fast algorithm based on the FFT are studied, and furthermore its complexity is analyzed. Then a reconfigurable implementation on the GPU is proposed, and a method of optimization that combines analysis with testing is proposed. By optimizing the dimension of the thread block and utilizing texture memory, the time of the kernel is reduced; the CUDA library is introduced, so the delays of the FFT and maximum searching are reduced. In comparison with the method in the 8-core CPU, the proposed method improves the overall performance up to 3.3 times. The speed can meet the challenge of real-time processing of the wideband matched filter.

    Optimization method for multimodal functions based on chaotic ant colony algorithms
    LIU Daohua;NI Yongjun;SUN Fang;ZHANG Fei
    J4. 2015, 42(3):  141-147.  doi:10.3969/j.issn.1001-2400.2015.03.024
    Abstract ( 744 )   PDF (1978KB) ( 641 )   Save
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    In order to quickly and accurately obtain the global and local peaks of multimodal functions, this paper proposes an optimization method for multimodal functions based on the henon chaotic ant colony algorithm. In this method, the numerical characters composed by numerical solutions of complex functions are turned into the nodes of the city distribution network on the ants searching paths, the ant colonies whose number is the same as the number of function variables are constructed to solve the problem by global search, and chaos mapping technology is used to update the pheromones on the ant colony optimization path adaptively. The solving performance of this optimization method is verified by adopting low-dimensional and high-dimensional benchmark test functions and compared with those of gravitational search algorithms and other methods in literature. The comparison results indicate that, in low-dimensional multimodal function optimizations, the search efficiency of this method is two times higher than that of other methods in literature, when the number of dimensions of high-dimensional functions is greater than five, the optimization efficiency of this method is basically the same as that of other methods. However, the ability of obtaining all the global and local solutions and the solving accuracy are much higher than those of other methods.

    Fast Bayesian non-local means of polarimetric  SAR image despeckling
    CHEN Jianhong;ZHAO Yongjun;SHI Yinshui;LIU Wei
    J4. 2015, 42(3):  148-153+204.  doi:10.3969/j.issn.1001-2400.2015.03.025
    Abstract ( 536 )   PDF (5950KB) ( 481 )   Save
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    Based on the Bayesian non-local means of the single polarization SAR, block similarity measurement of the polarimetric coherence matrix is derived by combining with the polarimetric coherence matrix adhering to complex Wishart distribution. The polarimetric SAR Bayesian non-local means model is given without prior knowledge. Then its fast algorithm is realized using the integral image. Finally, we verify the proposed algorithm with a full polarimetric image from AIRSAR to San Francisco district. Experimental results from real Polarimetric SAR data show that the proposed algorithm not only despeckes effectively but also preserves polarimetric information well. Besides, computing efficiency is improved greatly.

    New method for SAR occluded targets recognition using DNN
    LI Shuai;XU Yuelei;MA Shiping;NI Jiacheng;SHI Hehuan
    J4. 2015, 42(3):  154-160.  doi:10.3969/j.issn.1001-2400.2015.03.026
    Abstract ( 830 )   PDF (2174KB) ( 847 )   Save
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    For synthetic aperture radar(SAR) partial occluded images feature extraction and target recognition, a new method based on deep neural networks(DNN) is proposed. After preprocessing original images, we extract low-frequency sub-band images of SAR images in the wavelet domain as training data, and finally make a further extraction of the occluded targets' feature with the deep sparse autoencoder model as the input vectors. Three types of target in MSTAR database are used to simulate target occlusion and recognition experiment. Experimental results prove that the correct recognition rate could be improved by taking advantage of both local and global information about occluded targets, and that the new method is effective for feature extraction and object recognition of occluded SAR targets.

    Improved quadratic-form metric for  histogram distance measurement
    YU Wangsheng;TIAN Xiaohua;HOU Zhiqiang;LIU Bin
    J4. 2015, 42(3):  161-167+172.  doi:10.3969/j.issn.1001-2400.2015.03.027
    Abstract ( 646 )   PDF (3495KB) ( 946 )   Save
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    In order to improve the discrimination of histogram distance measurement, the problem of histogram distance measurement based on the quadratic-form metric is researched. Firstly, the traditional quadratic-form metric and its disadvantage are briefly reviewed. Then, an improved quadratic-form metric for histogram distance measurement is proposed by modifying the traditional quadratic-form distance function and the correlation matrix. Finally, the fast computation of the proposed metric and the measurement of high dimension histograms are discussed. The proposed metric takes a full consideration of the correlation between histogram bins, which increases its discrimination. Experiments based on shape matching, image retrieval and visual tracking validate the effectiveness of the proposed metric and its superiority over the traditional ones.

    Improved SO-FDTD method for non-magnetized plasmas
    ZHANG Hou;XU Zhiyong;YIN Xiong;ZHAO Zhenwei;WU Rui
    J4. 2015, 42(3):  168-172.  doi:10.3969/j.issn.1001-2400.2015.03.028
    Abstract ( 508 )   PDF (536KB) ( 552 )   Save
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    To improve the calculation efficiency of the FDTD method when dealing with the complex plasma problem, an improved shift operator-finite difference time domain(SO-FDTD) method for non-magnetized plasmas is prensented, and applied to calculate the reflection and transmission coefficients of the non-magnetized plasma flat, which provides a certain theoretical guidance to analysis of the propagation characteristics of the EM waves interacting with the plasma. The memory-minimized algorithm is applied to the method to save the system memory and improve the calculation speed. It is shown that the high efficiency and accuracy of the method are validated by comparing with the analytical method and the SO-FDTD method proposed in the recent references.

    Multi-objective ant colony optimization algorithm for  virtual machine placement
    ZHAO Jun;MA Zhong;LIU Chi;LI Haishan;WANG Xinyu
    J4. 2015, 42(3):  173-178+185.  doi:10.3969/j.issn.1001-2400.2015.03.029
    Abstract ( 532 )   PDF (511KB) ( 623 )   Save
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    The virtual machine placement schemes for existing data centers are mostly concentrated on optimization of energy consumption and resource waste. However, the optimization of datacenter network traffic was rarely considered, which may affect the network scalability. Therefore, with the consideration of both resource waste and total network traffic, this paper models the virtual machine placement as a multi-objective optimization problem, which optimizes the following two objectives in one time for data centers, i.e., minimizing physical machine resources to improve the physical machine efficiency and minimizing total network traffic to improve the network scalability. To solve this problem, we have designed a virtual machine placement algorithm based on multi-objective ant colony optimization (MOACO). Experimental results show that the proposed algorithm can effectively reduce physical machine resources waste and total network traffic compared with the FFD algorithm.

    Proportional fair resource allocation in the  relay enhanced cellular system
    MA Yanping;YANG Hongyong;MA Zhangchao;WANG Zengfeng
    J4. 2015, 42(3):  179-185.  doi:10.3969/j.issn.1001-2400.2015.03.030
    Abstract ( 619 )   PDF (710KB) ( 674 )   Save
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    This paper proposes a proportional fair(PF) resource allocation algorithm for the OFDMA cellular relay system. Assuming that both the base station(BS) and relay station(RS) can independently schedule users, the proposed algorithm can achieve proportional fairness for all users served by the BS and its subordinate RSs through a two-step resource allocation, i.e.,resource partition and user scheduling. Simulation results demonstrate that the proposed algorithm can achieve a good throughput-fairness trade-off.

    Facial expression recognition based on the binary code of edges
    FENG Xiaoyi;LAI Yangming;WANG Wenxing;CUI Shaoxing;PENG Jinye;JIANG Xiaoyu
    J4. 2015, 42(3):  186-191.  doi:10.3969/j.issn.1001-2400.2015.03.031
    Abstract ( 577 )   PDF (2644KB) ( 484 )   Save
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    Facial expression recognition mainly involves face locating, feature extraction, and expression classification. However, extracting effective features of facial expressions from original face images is a vital step for improving facial expression recognition. In this paper, a binary code of edge method is proposed for extracting the expression feature, which is used for facial expression recognition. Firstly, the face image is processed by an edge detection operator. Then, the proposed binary code method is applied to describe the edge binary image as the expression feature. Finally, the SVM classifier is used for facial expression recognition. Experiments are performed on JAFFE facial expression database, and the results show that the proposed method achieves a higher recognition rate than the traditional method.

    Novel broadband and rotated-patch antenna for wireless communication
    J4. 2015, 42(3):  192-197.  doi:10.3969/j.issn.1001-2400.2015.03.032
    Abstract ( 508 )   PDF (1547KB) ( 609 )   Save
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    A novel broadband rotated-patch antenna for wireless communication applications is proposed. By rotating the rectangular patches symmetrically, the bandwidth of the antenna can be significantly enhanced. Especially, the effect of the rotating angle and other geometry parameters on the bandwidth has been studied in detail. An antenna prototype is then fabricated and measured to verify the effectiveness of this design. The measured results indicate that the proposed antenna can achieve an impedance bandwidth (10dB return loss) as wide as 6.97GHz (2.29~9.26GHz) or the relative bandwidth is about 120.7%, which is nearly two times what the corresponding conventional cross monopole antenna does. Also relatively good omnidirectional radiation performance and antenna gain over the whole frequency range have been achieved.

    Robust watermarking utilizing adaptive order  dither block truncation coding
    XIE Kun;ZENG Ping;ZHENG Haihong;GUO Tao
    J4. 2015, 42(3):  198-204.  doi:10.3969/j.issn.1001-2400.2015.03.033
    Abstract ( 633 )   PDF (8769KB) ( 433 )   Save
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    To overcome the shortcomings of bad image quality or poor robustness of the current methods, a robust watermarking method based on adaptive order dither block truncation coding is proposed. Firstly, the image is adaptively divided into smooth regions, texture regions and edge regions using a quadtree segmentation, according to the information entropy and the variance. After that, these blocks are coded separately. Secondly, we exploit the bit plane obtained from adaptive order dither block truncation coding, and embed the watermark by changing the parity sum of the pixels within a window in the bit plane. Lastly, the watermark is retrieved with the parity sum and the majority voting strategy, not referring to the original image. The experimental results indicate that compared with the similar algorithm, the proposed method can achieve good image quality with a low compression rate, a high watermark rate and watermark rate flexibility. Moreover, it is robust to common attacks, especially to Salt & Pepper noising, brightness adjustment, contrast adjustment, rotating and cropping attacks.

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