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Table of Content

    25 May 2009, Volume 37 Issue 5
    Electronics, Communication & Automation Technology
    Liu Gui-kai Shan Chun-li Wei Gang Wang Hong-jiang
    2009, 37(5):  1-7. 
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    In order to reduce the routing overhead and improve the routing efficiency, a new Ad hoc subarea-tree routing protocol (ASTRP)-a hierarchical routing protocol-is proposed for multi-hop wireless Ad hoc networks. It establishes subarea trees to divide the whole network into many subareas each composed of a tree, and exhibits hy- brid behavior of proactive and on-demand routing protocols due to the function of routing selection of subarea tree. This paper presents the establishment process of ASTRP, proves the correctness of ASTRP and analyzes the routing storage overhead and routing updating overhead. The results show that ASTRP limits the effect of node failure among limited root nodes in a local area, and is of a lower routing updating overhead, as compared with other hierar- chical routing protocols.

    Ma Han-qing Chu Qing-xin
    2009, 37(5):  8-11. 
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    As the existing compact muhiband antennas are usually of complicated structure and unidirectional radia- tion, this paper presents a novel antenna applied to WLAN (2.45 GHz and 5.15 - 5.85 GHz) and WiMAX (3.50 GHz). The antenna is a monopole with modified top-loaded resonant structures that consist of folded strip lines in horizontal direction. It is compact in size with a height of only 10 mm and a width of only 13 mm. Moreover, it realizes the vertically-polarized omnidirectional radiation in the three operation bands. Experimental results show that the return loss of the antenna in the operation bands is less than - 10 dB, and that the antenna is suitable for mobile applications because it provides omnidirectional radiation patterns in the H-plane.

    Ji Yan-cheng Ge Jian-hua Gao Ming
    2009, 37(5):  12-16. 
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    In order to obtain a multi-path gain of orthogonal frequency division multiplexing (OFDM) in a space- time cooperative system, a space-time cooperative scheme based on the correlation of subcarriers in OFDM is pro- posed. In this scheme, by changing the order of the same signals in different phases of cooperative transmission, the signals are transmitted in two subearrier channels with the lowest correlation. Then, corresponding two-phase signals are combined together by the base station via a maximal ratio combing (MRC). Moreover, the outage pro- bability is analyzed, and an optimal power allocation strategy is proposed. Finally, the theoretical bit error rate is analyzed. Simulated results demonstrate that the proposed scheme results in significant gains in bit error rate (BER) performance, and helps to obtain one-order multi-path gains without reducing the transmission rate.

    Cheng Yan-hong Li Zhi-shu Zhu Li
    2009, 37(5):  17-22. 
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    In order to overcome the unfairness bandwidth allocation between uplink and downlink flows in an IEEE 802.11 infrastructure Basic Service Set (BSS) network, a novel bandwidth allocation scheme based on the transi- mission probability is proposed, which adjusts the access probability of access point (AP) or wireless terminals by controlling the transmission probability for a fair bandwidth allocation. The relationship between the optimal trans- mission probability for fair bandwidth allocation and the number of downlink flows is also investigated and is then used as a reference to the bandwidth allocation at AP or wireless terminals. Simulated results show that the proposed scheme leads to a fair bandwidth allocation between uplink and downlink flows.

    Lin Xiao-ling Kong Xue-dong En Yun-fei Zhang Xiao-wen Yao Ruo-he
    2009, 37(5):  23-26,42. 
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    The hot carrier effect (HCE) of SiGe heterojunction bipolar transistor (HBT) is generally rneasured using the voltage-accelerated degradation method at high reverse emitter-base (EB) voltages with open-circuit col- lector (OCSAM). However, when OCSAM is employed, the failure mechanism of SiGe HBT at high voltages is dif- ferent from that at low voltages, and the time cost is high. In order to solve these problems, the HCE reliability evaluation of SiGe HBT is carried out using the current-accelerated stress method at low reverse EB voltages and high stress current achieved by forward-biasing the collector-base (CB) junction (FCSAM). The variation of elec- trical characteristics before and after the application of stress is investigated and the degradation mechanism of elec- trical characteristics is analyzed. The results show that, with the increase of applying time of stress, the current gain gradually degrades. As compared with the conventional voltage-accelerated method OCSAM, FCSAM signifi- cantly saves the test time and can effectively predict the long-term reliability of SiGe HBT.

    Weng Xiao-guang Wang Hui-nan
    2009, 37(5):  27-30. 
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    As the fixed-point algorithm and the infomax algorithm, two of the most popular algorithms of indepen- dent component analysis (ICA), spend too much time in processing functional magnetic resonance imaging (fMRI) data, an optimization model of ICA is presented. Based on the model, a fast Newton iteration algorithm is pro- posed, in which an improved Newton iteration method is adopted to achieve a three-order convergence speed. The proposed algorithm and the two above-mentioned algorithms are then used to process real fMRI data. The results show that the proposed algorithm well separates the independent components from fMRI data with less computation and high convergence speed, and that it has obvious advantages in processing fMRI signals with huge numbers of data

    Lei Yun-qi Liu Xiu-xia Song Xiao-bing Yuan Mei-ling Ouyang Jiang-fan
    2009, 37(5):  31-37. 
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    In order to balance the detection quality and the computing speed of the existing human face-detecting methods, an algorithm for face detection and feature location of moving men in a video is proposed. In this algo- rithm, first, the approximate face region is detected using the Adaboost method. 'Next, the specific face region is determined using the skin color model, and the face part is picked up from the frame. Then, the video frame with a high face-region definition and a region as large as possible is selected by judging the image definition from the Peak Signal-to-Noise Ratio (PSNR) based on the difference between two neighbor frames in face region. Finally, the face detection and feature location of the video frame are performed. Experimental results indicate that, as com- pared with the existing face-detecting methods, the proposed method helps to perform more accurate feature location for corners of eye and mouth with higher calculating speed, the face-detecting rate being about 94.8%.

    Guo Jie Wu Cheng-ke Li Yun-song Ma Jing
    2009, 37(5):  38-42. 
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    In order to improve the performance of integer discrete wavelet transform (DWT) and the compression quality of images, a DWT architecture with high performance and low memory is proposed for JPEG2000. This architecture extends the precision of raw image data and effectively preserves the fractional bits of transformed coeffi- cients in lifting steps. It adopts a memory scheme of wavelet coefficients based on code block strips to reuse and schedule the memories with code block strips in sub-bands, thus reducing the hardware resources in terms of sto- rage and power consumption. Experimental results show that the proposed scheme effectively improves the compres- sion quality of images, and that, by decomposing a 512 × 512 image using a code block in the size of 32 × 32, the memory of the proposed architecture is only 20% that of the scheme directly buffering all the coefficients in the transformed image. The proposed architecture has passed the FPGA verification and the synthesized clock frequency of it is up to 150 MHz

    Luo Zhong-liang Lin Tu-sheng
    2009, 37(5):  43-48. 
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    The existing iris recognition algorithms are of low executing speed and poor robustness. In order to im- prove the accuracy of iris recognition, a novel preprocessing approach is proposed according to the characteristics of iris images. In this approach, first, the least square method is used to locate the inner iris boundary and to test the eyelid. Next, the improved randomized Hough transform is adopted to locate the outer iris boundary. Then, the double-threshold method is employed to detect the eyelash. Finally, a normalizing, de-noising and enhancing process is performed for the circular iris image. The iris image after the preprocessing basically eliminates the dis- turbance of eyelid and eyelash, thus facilitating the following extraction and matching of iris features. Experimental results demonstrate that the proposed approach effectively overcomes the long runtime and the poor generality in image preprocessing, and improves the stability and accuracy of iris recognition system.

    Ma Yi-de Su Mao-jun Chen Rui
    2009, 37(5):  49-53. 
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    In order to overcome the weak adaptability and the difficulty in selecting the adaptive threshold of the traditional image binarization and to improve the reliability lacking in the traditional single evaluation of image seg- mentation, an image binarization method based on pulse-coupled neural network (PCNN) is investigated, and the corresponding parameters are selected. Afterwards, a composite segmentation evaluation method comprehensively considering various evaluation criteria is proposed. Experimental results show that the PCNN-based image binariza- tion method is of high accuracy and is suitable for the segmentation of varied images, and that, as compared with the traditional single evaluation methods, the proposed composite method can evaluates the performances of segmen- tation algorithms more objectively and accurately.

    Li You-xin Mao Zong-yuan Tian Lian-fang
    2009, 37(5):  54-58,89. 
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    In order to improve the universality of the traditional visual servoing control methods based on image fea- tures and to reduce the complexity of the marking, extracting and matching of image features, a novel plane visual servoing control method is proposed based on artificial immunity and direct image feedback. In this method, first, the translation and rotation errors between the reference and feedback images are obtained by employing an artificial immune algorithm. Then, the position and orientation increments transformed from the image errors via a visual controller are transmitted to the robot controller, which implements the closed-loop visual servoing control without marking and extracting any image features. Experimental results indicate that the proposed method makes the robot accurately track objectives with an error under one pixel, showing its effectiveness and correctness

    Jia Li Tao Peng-ye Qiu Min-sen
    2009, 37(5):  59-63. 
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    In order to overcome the nonlinearity and time-varying uncertainty of actual industrial processes, an adaptive control system based on linearization error model is proposed. In this system, first, a composite model consisting a ARX model and a linearization error model based on the neuro-fuzzy system is constructed to describe the nonlinear process. Then, by employing a single-neuron controller and by considering the error between the ARX model output and the system output, as well as the gradient information of the composite model, the controller pa- rameters are adjusted online with high control performance. Simulated results indicate that, as compared with the conventional PID controller, the proposed adaptive controller based on linearization error model is of higher response speed.

    Cen Jian Zhang Qing-hua Xu Bu-gong Gao Ting-yu
    2009, 37(5):  64-67. 
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    As slowly-varying faults are difficult to detect, a detection method based on the nondimensional immune detector is proposed. In this method, first, a generation algorithm of immune detector based on biological immune principle and evolutionary mechanism is combined with the nondimensional parameters to construct five nondimen- sional immune detectors. Next, in order to detect small variations, the negative selection algorithm is adopted and a proper code length is selected to deal with the extracted data. Then, with the cross-detection using multiple non- dimensional immune detectors and with the integration and fusion of test data, comprehensive fault information is obtained. After an offline training, the multiple nondimensional immune detectors are finally used for the online de- tection of slowly-varying faults. Simulated results and practical application both indicate that the proposed method effectively detects slowly-varying faults on line

    Zhang Yu-nong Zeng Yan Zhong Tong-ke Tang Zhi-shuang Mo Hong-qiang
    2009, 37(5):  68-72. 
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    By using numerical algorithms to solve inverse-interpolation problems, the accuracy of positive solution is influenced by the choice of initial values, and the computational speed is slow. In order to solve the problems, a power-excitation feedforward neural network is employed to solve inverse-interpolation problems. As the adopted neural network is only suitable for the inverse-interpolation problem with one-to-one mapping but not for that with multiple-to-one mapping, the timing control condition is introduced into the neural network to construct a timing power-excitation feedforward neural network model. Theoretically derived and simulated results indicate that the constructed neural network effectively solve the inverse-interpolation problems with both one-to-one and multiple-to- one mappings.

    Zhang Dong-zhi Hu Guo-qing Xia Bo-kai
    2009, 37(5):  73-78. 
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    In order to improve the on-line measuring accuracy and widen the measuring range of water content of crude oil, a simulated multi-sensor measurement system of oil/water two-phase flow is adopted to detect the para- meters influencing the measurement, and an intelligent compound model for measuring the water content is estab- lished by combining the rough set preprocessor, the support vector machine classifier and the genetic neural network predictor. Experimental results show that the proposed model effectively eliminates the cross interference of oil/wa- ter emulsion modal, temperature and salinity content, overcomes the nonlinearity of sensor itself, realizes the modal identification of oil-water mixture via fuzzy reasoning and self-learning, and adjusts the model parameters by changing working conditions adaptively. Thus, the accuracy of on-line intelligent measurement of water content of crude oil is effectively improved in a wide measuring range.

    Li Jun Chen Guo-hua Ma Tie-jun Zeng Qi-lin
    2009, 37(5):  79-83. 
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    The correlation fringes obtained by traditional methods in digital speckle pattern interferometry are se- verely contaminated by speckle noise, which results in a low signal-to-noise ratio in fringes. To overcome this di- sadvantage, a novel approach to the generation of correlation fringes based on cross-entropy is presented by taking into account the concept of cross-entropy and the basic principles of fringes representation for the state change in digital speckle pattern interferometry. The quantitative results of theoretical deduction and practical applications in- dicate that the correlation fringes obtained by the proposed method are essentially coincident with the subtraction fringes, and that, due to the integration of adaptive homomorphic filtering into the generation of cross-entropy frin- ges, the proposed approach may result in higher fringe contrast, smaller speckle index and better quality of wrapped phase map.

    Computer Science & Technology
    Wang Jian-xin Zhu Jing Liu Yao
    2009, 37(5):  84-89. 
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    As the flooding-based routing algorithms for delay-tolerant networks have a serious message copy redun- dancy and the copies of message in some social networks diffuse locally, a routing algorithm based on copy restriction and sociality (RACS) is proposed, in which the message copy redundancy is reduced by restricting the maxi- mum number of message copies, and the centralities of nodes during the diffusion are compared to provide more message copies for a node with higher centrality rank. Thus, the diffusing and delivering of message copies are both well implemented. Simulated results show that, as compared with other routing algorithms, the proposed algorithm makes the delivering ratio increase by 5% and the average delivering delay decrease by 10% when the maximum number of message copies is 6.

    Zhang Lian-ming Liu Sun-along
    2009, 37(5):  90-93,105. 
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    In order to avoid the network performance degradation due to the burst characteristics including Internet self-similar traffic, etc. , a mathematical model of loss fractal regulator controlling the self-similar traffic is pro- posed. The performances of the regulator including the queue length and the delay are analyzed, and the influences of the introduction of the regulator on the end-to-end delay, the total packets loss and the average loss rate are dis- cussed. Then, the relationship between the upper bounds of the above-mentioned performance indexes and the pa- rameter of self-similar traffic are investigated. Moreover, the buffer minimum of the loss fractal regulator at the maxi- mum average loss rate is obtained. The above-mentioned results provide a useful reference to the evaluation of con- gestion control scheme and traffic management scheme of self-similar traffic and to the design of parameters of the loss fractal regulator

    Zhao Jie Xiao Nan-feng Zhong Jun-rui
    2009, 37(5):  94-100. 
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    The existing evaluation methods of network user behaviors are of high cost and low practicability. In or- der to effectively forecast and evaluate network user behavior trust with ease, a trust forecast and control algorithm of user behaviors is proposed based on Bayesian networks, in which the clustering algorithm and the distribution density function are used to set parameters, and the corresponding relationship between quantitive evidence and trust grade is obtained. Afterwards, the configurable plug-in of trust management is implemented based on IIS and. Net framework to create user behavior logs, thus providing evidences for the forecast and control algorithm and avoiding the data cleaning of common Web logs. Experimental results indicate that the proposed algorithm is capable of predicting the trust grade in multi-trust-attribute conditions, improving the security and reliability of the server and restricting the trade behaviors of the user.

    Wang Zhen-yu Deng Jin-fu
    2009, 37(5):  101-105. 
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    In the monitoring and the statistics of domain name system (DNS) security, DNS query logs may reduce the DNS performance, and the lagging progress may result in an unusual disposal. In order to solve these problems, a DNS real-time monitoring and statistical system (DRMSS) is designed based on a multi-level framework. DRMSS uses a BSD packet filter (BPF) to filter DNS service message and employs the memory caching mechanism to store and handle the real-time monitoring and statistical information. Experimental results indicate that DRMSS is sui- table for the real-time monitoring and statistical integration of multi-domain name service software, and greatly im- proves the service performance and security of DNS.

    Chen Shu-yi Wen Ying-you Zhao Hong
    2009, 37(5):  106-110. 
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    A formalized analysis method of trusted computing is proposed based on conditional predicate logic which fomally verifies trusted computing models. In this method, different predicates and reasoning rules are defined, and the factors to influence the credibility are added in the predicate logic as constraint conditions. Thus, the trusted computing models are successfully verified. Moreover, the secure bootstrap process of the trusted computing plat- form is analyzed via an example, and a secure bootstrap process of the trusted computing platform with constrained delegation length is proposed. The results show that the proposed method can be clearly and effectively used for the formalized analysis of trusted computing models.

    Ge Li-na Tang Shao-hua
    2009, 37(5):  111-117. 
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    In order to improve the security of the authentication scheme based on geometric properties, an identity authentication and key agreement scheme based on circle properties is proposed, the basic principle of which is that an n-dimension circle can be reconstructed by any n + 1 n-dimension points on it, and a multi-variable one-way hash function is used to calculate the login message and to improve the robustness of the login message for security. Thus, the scheme ean withstand the attacks, such as the password guess, replay, eavesdropping and off-line mes- sage analysis. The proposed scheme is proved secure by a formal approach at last.

    Li Ming-xiang Han Bo-tao Zhu Jian-yong Zheng Xue-fen Yan Peng
    2009, 37(5):  118-122,129. 
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    The existing identity-based proxy signature schemes are secure in the random oracle model but not al- ways secure in the real world. In order to solve this problem, a security model of identity-based proxy signature schemes is presented, and a new identity-based proxy signature scheme is proposed. The security of the proposed scheme is then proved based on the computational Diffie-Hellman assumption without using the random oracle heu- ristic in the presented security model. The results indicate that, as compared with the efficient identity-based proxy signature scheme recently presented, the proposed scheme only needs an additional bilinear mapping.

    Yin Xun-fu Hao Zhi-feng
    2009, 37(5):  123-129. 
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    In order to accelerate the computation of kernel density estimation (KDE) and to reduce the complexity of KDE model, a fast KDE algorithm based on sparse Bayesian regression is proposed. The algorithm takes the jittered approximation of the distribution function as the input and obtains the very sparse representation of KDE. Experimental results indicate that, as compared with the conventional KDE algorithm, the proposed algorithm results in a much smoother density estimation when training with a small sample set, and it remarkably improves the space-time efficiency with a comparative computational precision and with a reduced model error in most cases. Moreover, the applications of independent component analysis and Gaussianization to the proposed algorithm allevi- ate the curse of dimensionality to some extent.

    Cai Qian-feng Hao Zhi-feng Yang Xiao-wei
    2009, 37(5):  130-134. 
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    In order to improve the generalization capability of Takagi-Sugeno-Kang (TSK) fuzzy model in high-di- mension space, a novel algorithm of TSK model is proposed based on the structural risk minimization principle. In this algorithm, first, the antecedent membership functions of fuzzy rules are obtained by means of the Gustafson- Kessel (GK) algorithm. Next, the consequent parameters of fuzzy rules are determined by using the least-square support vector regression (LSSVR) machine. Then, the kernel function of LSSVR is deduced by the antecedent membership functions of fuzzy rules and is proved to be a Mercer kernel. Experimental results show that the pro- posed algorithm has better generalization capability than the conventional techniques of TSK model and is more ro- bust than LSSVR.

    Zhang Qi Xu Zhi-jian Zhao Kun-rong
    2009, 37(5):  135-138. 
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    In order to provide valuable prediction data for the decision making of environmental protection, a model to predict the data of pollution sources is proposed based on Elman neural network. By using the proposed model and by taking SO2--the main pollutant in the atmosphere--as an object, the complex relationships between SO2 concentration and the factors, including the air temperature, the relative humidity, the wind speed, the time and the historical date, are investigated. After training, the proposed model is used to perform a simulation. The results demonstrate that the outputs calculated with the proposed model accord well with the sample outputs, and that the proposed model is more effective than the prediction model based on BP neural network.

    Li Dong Yuan Ying-hua Ye You Liu Zhen-yu
    2009, 37(5):  139-144. 
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    In order to overcome the disadvantages of the traditional strategy for semantic caching coherency mainte- nance, such as the large data communications flow, the slow update speed and the large occupation of memory space, a new algorithm of semantic caching coherency maintenance based on attribute update is proposed. In this algorithm, the relationship between the semantic caching segment and the conditional predicate as well as the pro- jection attribute of the update operation is analyzed, and a semantic trimming is performed, thus fining the update operation to the exact attribute size. The results of theoretical analyses and simulated experiments show that the new algorithm effectively increases the cache hit ratio, saves the data communication cost and the update time of cache and reduces the data access occupation.

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