Table of Content

25 January 2009, Volume 37 Issue 1

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Electronics, Communication & Automation Technology

A Stable Rapid Synchronization Algorithm for Direct-Spread Ultra-Wideband Systems

Wang Hong-jiang Wei Gang Liu Gui-kai Feng Yi-zhi Liu Lei-an

2009, 37(1):  1-5. 

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In order to improve the reliability and speed of the synchronization algorithms for a direct-spread ultrawideband communications system, a stable rapid synchronization algorithm is proposed to acquire the path signal with the maximum energy, with the mean acquisition time being also formulated. In this algorithm, the characteristics of indoor muhi-path propagation and multi-hypothesis rapid synchronization algorithms are considered, and the path signal with the maximum energy is rapidly acquired for the stable timing synchronization. Simulated results indicate that the proposed algorithm is more rapid and stable than the existing synchronization algorithms.

Extraction of Equivalent Circuits of Suspended Stripline T-Junctions

Chu Qing-xin Zhou Jing-ke

2009, 37(1):  6-9. 

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In order to design phase shifters with high accuracy, the equivalent circuits of the single-chip-coupling suspended stripline T-junction and the dual-chip-coupling U-shape suspended stripline T-junction are presented based on the stripline structure and the transmission line model. The circuits are then employed to calculate the S parameters （magnitude and phase） of the T-junctions, and the results are compared with the ones from Ansoft HFSS simulation and measurement. It is found that the proposed equivalent circuits are effective in designing the phase shifter with electrically-controlled antennas.

Design of Triple-Band Filter Based on Assembled Multiband Resonator

Chen Fu-chang Chu Qing-xin

2009, 37(1):  10-14. 

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In order to obtain triple-band bandpass filters with independently-controlled center frequencies and bandwidths, this paper presents a novel design method of triple-band filters based on the assembled multiband resonator. In this method, first, a stepped impedance resonator and a half-wavelength resonator are both employed to construct an assembled muhiband resonator. Then, two kinds of triple-band filter configurations with cascaded and pseudo- interdigital formats are designed, both of which possess sufficient freedom to satisfy the requirements of bandwidth and center frequency. Finally, two filters operating at 2.45, 3.50 and 5.25 GHz are designed and fabricated. The measured results of the filters accord well with the simulated ones, meaning that the proposed design method is feasible.

Numerical Simulation of Unsaturated Output Current of Amorphous-Silicon Thin-Film Transistors

Liu Yuan Yao Ruo-he Li Bin

2009, 37(1):  15-18,23. 

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In order to overcome the unsaturated output current of hydrogenated amorphous-silicon thin-film transistors （ a-Si ： H TFTs）, the output characteristics of a-Si ： H TFTs are numerically simulated by using the semiconductor device simulation software, and the generation mechanism of the unsaturated output current is discussed. Simulated results show that, in long-channel semiconductor devices, the conduction of bulk current changes into a space charge-limited mode due to the increase of drain-source voltage, which is the main reason for the unsaturated output current, and that, in short-channel semiconductor devices, the drain-induced barrier lowering effect should be meanwhile considered.

Design of Waveguide Power Divider at W Band

Mei Zhi-lin Wang Zong-xin Dou Wen-bin

2009, 37(1):  19-22. 

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As for the waveguide power divider, an important component in microwave and millimeter wave systems, its traditional matching structure is difficult to realize at W band due to the machining difficulties. In order to solve this problem, this paper proposes an arc structure via the finite element method based on the weak form of Helmhohz equation. As the radius of the arc structure is that of the milling cutter, the structure contour matches well with the outer fringe of milling cutter and can be easily manufactured with a common milling machine, thus effectively reducing the manufacture cost. Moreover, a H-plane waveguide power divider and an E-plane one are designed using two pairs of arcs and three pairs of arcs, respectively. It is proved that the proposed design method is of engineering applicability because the calculated scattering parameters accord well with the experimental ones.

Application of Support Vector Machine to Reliability Evaluation of Small-Sample IC

Zou Xin-yao Yao Ruo-he

2009, 37(1):  23-26. 

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It is difficult to obtain accurate evaluation results in dealing with small-sample electronic devices by using the traditional methods in practice, because the small samplecan not accord with the large sample-based hypothesis of the traditional methods. In order to solve this problem, this paper proposes a reliability evaluation method of small-sample electronic devices based on the support vector machine （SVM）. In this method, after the training of failure time of electronic devices, the optimal kernel function and parameters are selected to construct a SVM model, and the reliability parameters are evaluated according to the straight line fitted by the SVM model. Evaluated results of the life distribution of a gate oxide indicate that the proposed method is more accurate than the least square method based on large sample.

Fading Characteristics of HAPS Communication Channel in Dynamic Environment with Low Elevation Angle

Yang Ming-chuan Jiang Yi-cheng Guo Qing Na Zhen-yu

2009, 37(1):  27-33. 

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In this paper, first, the coverage, link loss and rain attenuation characteristics of high-altitude platform station （HAPS） communications systems are analyzed. Next, according to the channel characteristics of the dynamic environment with a low elevation angle and on the basis of the propagation seaterring theory, a statistical mixedstate fading model is proposed by introducing a shadow coefficient. Then, the higher-order statistical characteristics of the model in different states are formulated. Finally, the first-order and higher-order statistical characteristics of the model are compared using the measured data, exact accordance being revealed. It is thus concluded that the proposed model is effective in analyzing the propagation characteristics, optimizing the modulation and coding schemes and simulating the performance of HAPS communication systems.

Target Tracking Based on Nonparametric Clustering and Multi-Scale Images

Jiang Zhuo-lin Li Shao-fa Jia Xi-ping Zhu Hong-li

2009, 37(1):  34-41. 

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In order to track a target in space and scale in a complex background, a target tracking algorithm based on the nonparametric clustering and multi-scale images is presented. In this algorithm, first, a modified nonparametric color-clustering method is employed to adaptively partition the color space of a tracked object, and the Gaussian function is used to model the spatial information of each bin of the color histogram. Next, the Bhattacharyya coefficient is adopted to derive a function describing the similarity between the target model and the target candidate. Then, a coarse-to-fine approach of multi-scale images is employed to implement the spatial location of the tracked object. Finally, the derived automatic bandwidth selection method of kernel function is applied to obtain the scale of the tracked object. Experimental results show that the proposed algorithm outperforms the classical mean shift tracker.

Weighted Structural Similarity Based on Block Classification of Image

Yang Chun-ling He Liu Wei Yi Mai Zhi-yi

2009, 37(1):  42-47. 

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Although the Structural Similarity （SSIM） method, a structural information-based method for image quality assessment, performs well with low computational complexity, it is still of some disadvantages because it simply takes the average SSIM of sub-blocks as the mean SSIM （MSSIM） of the whole image without considering the difference of human visual sensitivity in different image areas. In order to solve this problem, this palper proposes a block classification-based image quality assessment method named Weighted Structural Similarity （WSSIM）. In this method, an image is separated into some blocks that are further divided into edge blocks, detail blocks and smooth blocks, and the SSIMs of different types of blocks are weighted with different values to calculate the WSSIM of the whole image. Experimental results indicate that the proposed method is superior to the MSSIM method and the variance-based weighted SSIM.

Algorithm of Noise Reduction and Contrast Enhancement for Intravascular Ultrasound Images

Li Hong Wang Hui-nan Dong Hai-yan Zhang Xiao-guo

2009, 37(1):  48-53. 

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In order to overcome the blood-speckle noise and ambiguous boundary in intravascular ultrasound （IVUS） images, this paper proposes an algorithm for noise reduction and contrast enhancement based on the dyadic wavelet transform. In this algorithm, first, the noise variance is estimated according to the characteristics of IVUS images. Next, a method to calculate the local threshold is proposed based on the decomposed structure of dyadic wavelet transform. Then, the wavelet coefficients in different scales are treated using the shrinkage techniques which combine the soft threshold filtering with the hard one. Finally, a contrast enhancement algorithm is proposed based on the stretching of wavelet coefficient extreme and on the interpolating with Hermite polynomials. Experimental results indicate that, as compared with the existing denoising methods, the proposed algorithm is more practicable because it not only reduces the blood speckle noise but also enhances the image contrast without eliminating image details.

An Improved Approach to Fast Computation of Pseudo-Zernike Moments

Huang Rong-bing Du Ming-hui Liang Guo-ying Xie De-xin

2009, 37(1):  54-58,90. 

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In order to effectively apply pseudo-Zernike moments to the image analysis and the pattern recognition, an improved approach to the fast computation of pseudo-Zernike moments, which uses Clenshaw recurrence formula to implement the fast computation of pseudo-Zernike moment polynomial summation, is proposed to reduce the computational complexity of the traditional approaches. Preliminary experimental results demonstrate that the proposed approach costs less CPU time than the traditional methods in terms of computing special-order moments, and that it is of a recognition rate 5% more than that of the traditional principal component analysis method in terms of extracting and recognizing face features, with an average extraction time of 1.2 s.

Edge Detection Method Based on Kernel Principal Component Analysis and Subspace Classification

Lin Zheng-chun Wang Zhi-yan

2009, 37(1):  59-63. 

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In order to enhance the robustness of the traditional edge detection methods to noises, an edge detection method based on the kernel principal component analysis （KPCA） and the subspace classification is proposed, and a unified model to represent image features is established. First, the proposed method combined with other edge detection methods selects samples which map in the feature space, and then builds a subspace in the feature space with the eigenvetors obtained via KPCA..Afterwards, it expands the subspace classification into the feature space for data classification. Experimental results indicate that the proposed method is robust to noises and is suitable for small-sample training, and that the detection accuracy of the method is higher than that of the classical operators, the principal component analysis （PCA） and the nonlinear PCA.

Shadow Detection Algorithm Based on Gabor Wavelet and Color Model

Bai Ke-jia Liu Wei-ming Tang Yi

2009, 37(1):  64-68. 

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In order to effectively detect the shadow areas in image sequences and to eliminate the serious effect of shadows on the object tracking and recognition, this paper proposes a new shadow detection algorithm based on the Gabor wavelet and the color model. In this algorithm, first, the Gaussian mixture distribution model and shadow color model of the background are established. Next, the foreground figures are extracted by means of the difference method. Then, the potential shadow pixels are found out by means of Gabor wavelet texture analysis, which are further analyzed with the shadow color model to search real shadow pixels. Finally, the real shadow areas are distinguished after some subsequent processing steps. Experimental results demonstrate that the proposed algorithm is of high performance of shadow detection.

Real-Time Motion Detection Model Using Block-Based Statistical Moment

Lü Chang-kui Wang Ning-sheng Xu Yan

2009, 37(1):  69-73. 

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In order to improve the robustness of real-time motion detection systems, a variation coefficient is used to calculate the block-based statistical moment, to describe the variations of frame sequences, and the colinearity test is employed to obtain the maximum likelihood estimation of the variation coefficient. Then, based on the maximum likelihood ratio of the variation coefficient of successive blocks, a novel three-frame difference motion detection model is established. Experimental results indicate that the proposed model is suitable for the detection of whole silhouette of a moving object and is robust to the gradual illumination change, the shadow and the background vacillation, etc.

A New Fusion Algorithm of Weighted Information from Knuckleprint and Vein

Mao Xian-guang Lai Xiao-zheng Lai Sheng-li

2009, 37(1):  74-78. 

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In order to solve the problems of few detail information and relatively high false-rejection and falseacceptance rates in vein recognition, a new fusion algorithm of the weighted information from knuckleprint and vein is presented. In the preprocessing stage of knuckleprint, an 8-neighborhood method is used to accurately locate the basic points of palm, and the straight-line fitting technique is adopted to fit the contour of finger and to further locate the region of interest （ROI） of knuckleprint. In the matching stage of image, the characteristics of knuckleprint are extracted using a Gabor filter and is then fused with vein information via the weighted fusion technology. Simulated results indicate that the proposed algorithm improves the recognition rate and system stability.

Quantum-Inspired Evolutionary Algorithm to Solve Multi-Objective Numerical Optimization Problems

Yang Chun Deng Fei-qi Yang Hai-dong

2009, 37(1):  79-85. 

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In order to improve the convergence rate and preserve the diversity of the solutions to multi-objective numerical optimization problems, a quantum-inspired evolutionary algorithm is presented based on the principles of quantum computation and multi-objective optimization. In this algorithm, first, a crowed comparison operator is used to sort and select individuals according to the characteristics of multi-objective optimization. Then, a non-uniform mutation operator is applied to the observation populations to preserve the convergency of the solutions and to improve the precision of local search. Finally, a diversity-preserving operator is employed to delete the observation populations for the purpose of preserving the solution diversity. Experimental results show that, as compared with the NSGA-Ⅱ algorithm, the proposed algorithm is of higher convergence rate and better population diversity

Algorithm of Heterogeneous Neural Network Ensemble Based on New Evolutionary Programming

Wang Li Zhu Xue-feng

2009, 37(1):  86-90. 

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In order to improve the generalization ability of ensemble algorithms and the objectivity of the generating process of individual networks, an algorithm of heterogeneous neural network ensemble is proposed based on a new evolutionary programming. In this algorithm, several heterogeneous optimal neural networks are generated based on an improved evolutionary programming and are further integrated to obtain a solution. Simulated results indicate that, as compared with the traditional ensemble algorithms with fixed network structure and low individual precision, the proposed algorithm is of stronger generalization ability and fewer random elements.

Computer Science & Technology

A Parallel Closed-Cubing Algorithm Based on MapReduce

Xi Jian-qing You Jin-guo Tang De-you Xiao Wei-ji

2009, 37(1):  91-95,112. 

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Although the closed cube is a high-efficiency and important technology for data cube compression, there is no research on its parallel algorithm at present. In this paper, a novel parallel approach combining the C-Cubing technology with the MapReduce framework is proposed. In this approach, the representative tuple and closed mask of each data cell for every data block are computed in the Map process, and the closed cells are obtained by the aggregation in the Reduce process. Experimental results show that the proposed approach greatly increases the computation speed of closed cubes in large-scale datasets.

Ontology-Based Fusion Method of Semantic Data

Liu Bo Qi De-yu Lin Wei-wei Pang Xiong-wen

2009, 37(1):  96-101. 

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This paper deals with the semantic data access on demand in the grid environment and proposes a novel ontology-based semantic data fusion method named OSDF. In this method, the dataset is taken as the basic element, the mapping between the domain ontology and the dataset is used to obtain the semantics of the dataset, the nested relation model is employed to represent the pattern information of the dataset, and all the datasets integrated in a grid node are regarded as the datasets of the next node to perform a fine-to-coarse data fusion. Moreover, by defining the semantic model of OSDF and proposing the query-executing process and algorithm of the virtual database, a semantic-supported and QoS-supported data access is provided for users. The correctness and feasibility of OSDF are finally verified by a prototype.

Elitism-Producing Strategy in Gene Expression Programming

Hu Jian-jun Peng Hong

2009, 37(1):  102-105. 

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In order to improve the evolutionary efficiency of gene expression programming （GEP） algorithm, an elitism-producing strategy （EPS） is proposed to obtain the GEP initial population. By gradually increasing the distance between the chromosome and the aim, the chromosome with high fitness is randomly obtained in a short time. Thus, elitisms can be rapidly produced from the initial population and the evolution can be started at a higher level. As a result, the evolution distance of GEP algorithm shortens and the evolutionary efficiency increases. Experimental results show that the proposed strategy raises the evolutionary efficiency of GEP algorithm by 17% in the process of function mining.

C-SHOIQ： a Cloud Extension to Description Logic SHOIQ

Liu Jie Fan Xiao-zhong Chen Kang Lin Pei-guang

2009, 37(1):  106-112. 

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In order to overcome the shortcoming of the classical description logic in the expression of uncertain knowledge, this paper proposes a new cloud-based description logic C-SHOIQ （Cloud-SHOIQ） by combining the description logic SHOIQ with the fuzzy logic. In the investigation, first, the syntax and semantics of C-SHOIQ are presented, and the capability of processing the randomness and fuzziness of knowledge is analyzed by some exampies. Next, the reasoning approach of C-SHOIQ and the improved rules mapping the C-SHOIQ KB （Knowledge Base） to the classical SHOIQ KB are described. Then, the consistency of the satisfiability between C-SHOIQ concepts and corresponding classical SHOIQ concepts is demonstrated. Finally, the extension of expression ability of fuzzy SHOIQ to C-SHOIQ is demonstrated.

A New Generation Method of Fractal Sequence

Chen Chu Xu Yong Zhang Ling

2009, 37(1):  113-118. 

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As the existing generation algorithms of fractal sequence can only generate monofractal or muhifractal sequences, this paper proposes a new generation method of fraetal sequence named variance-adjusting random dichotomy （VARD）. By using the proposed method, a monofractal or multifraetal sequence can be generated by adjusting the input argument σ, and the self-similarity of a monofractal sequence and the Legendre spectrum of a multifractal sequence depend on the input argument. Simulated results indicate that the proposed method helps to rapidly generate self-similar sequences with high accuracy and fractal sequences with various local bursts, and is convenient to the simulation of different network traffics.

Ant Colony Algorithm-Based Fair Routing Algorithm for Wireless Mesh Networks

Liu Yong-guang Ye Wu Feng Sui-li Zhuang Hong-cheng

2009, 37(1):  119-123,129. 

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As the centralized management architecture adopted by wireless Mesh networks often results in unbalanced bandwidth and load allocation, this paper proposes a fair bandwidth-allocation routing algorithm based on the ant colony algorithm by introducing a fair routing evaluation standard named minimum per-user average bandwidth. In the proposed algorithm, the traffic load is balanced and the bandwidth is fairly allocated for each user by maximizing the minimum per-user average bandwidth with the aid of optimization function of ants＇ travelling. Simulated resuits indicate that, as compared with the existing algorithms, the proposed algorithm may result in fairer bandwidth allocation though both the complexity and the average path length increase.

Bluetooth-Based Load-Balancing Convergecast Protocol for Wireless Sensor Networks

Xie Rong Qi De-yu Dong Min Li Yong-jun

2009, 37(1):  124-129. 

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In order to balance the load of the existing data convergecast protocols in wireless sensor networks, this paper proposes a novel load-balancing convergecast protocol （LBCP）. LBCP constructs the Bluetooth scatternet branch based on the competition algorithm, and updates the load information with the method combining the ＂ondemand notice mechanism＂ with the ＂fault detection mechanism＂, thus overcoming the incapability of the conventional algorithms in adapting traffic change and reducing load-updating frequency. Simulated results indicate that, as compared with the conventional protocols, the proposed protocol is of higher data delivery ratio and stabler data transmission rate.

Clustering Algorithm of Web Search Results Based on Conceptual Grouping

Li Hong-mei Ding Zhen-guo Zhou Shui-sheng Zhou Li-hua

2009, 37(1):  130-134. 

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In order to facilitate the browse of the search results obtained by search engines and to rapidly and effectively find valuable Web documents, this paper proposes a new clustering algorithm of Web search results based on the conceptual grouping. In this algorithm, first, the co-occurrence networks of characteristic terms are built. Next, the semantic relationships among characteristic terms are mined via the conceptual grouping to form different clusters related to the query topic. Then, the distances between the Web documents and the formed clusters are calculated for the clustering of Web search results. Finally, the cluster labels are selected according to the importance of characteristic terms in the search .results and the clusters. It is indicated by experiments that the proposed algorithm performs better than the k-means algorithm, and that the labels selected by the algorithm are apprehensible.

Design and Implementation of High-Performance FTP Search Engine

Guo Li-li Zhao Chun-jiang

2009, 37(1):  135-139. 

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In order to improve the query quality of the traditional FTP search engines possessing low optimization performance for query results, a high-performance intelligent FTP search engine is designed based on the statistical analysis of FTP user query logs. In this engine, the double-byte inverted index is employed to build an inverted index table with every double bytes of the file name, the automatic classification of query results is used to establish a tree structure of query results based on the search topic, and the automatic error correction is adopted to construct a spelling mistake dictionary with the high-frequency search keywords in user query logs. Query results in a real system indicate that the proposed scheme greatly improves the query efficiency and quality of a FTP search engine.

Safety Mechanism of Dynamic Service Flow

Cao Yong-zhong Ding Qiu-lin Li Bin

2009, 37(1):  140-144,150. 

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In order to avoid the benefit loss of certain individuals in the benefit competition set due to the sensitive information leakage resulting form the flow of service structure information in all nodes, and to ensure the parallel operation of nodes with high information security, this paper defines a dynamic Web service flow, proposes the nonsensitiveTree and sensitiveTree algorithms to separate sensitive variables from the dependence expression of simultaneous place, and designs dependence expression trees for different objects. Afterwards, a synchronous agent is constructed to manage the information publishing, thus implementing the management of dynamic service flow with security. Experimental results show that the proposed system can not only manage the dynamic operation butalso guarantee the information security of services of each benefit individual.

Grid Algorithm Based on Approximate Function for Injection Warpage Optimization

Cui Zhen-dong Gao Yue-hua Wang Xi-cheng

2009, 37(1):  145-150. 

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In order to integrate the massive idle resources to solve the large-scale numerical problems and to save the time for engineering optimization design, this paper proposes a grid algorithm based on the approximate function for injection warpage optimization. By employing the Kriging surrogate function, the massive idle resources are integrated to implement the effective coordination and share of grid resources. After the introduction of the theory and execution flow of the proposed algorithm, the optimization design of a mobile phone cover is performed, the results verifying the effectiveness and rationality of the algorithm.