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05 April 2008, Volume 34 Issue 7
    

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  • WANG Guang-xin; WANG Zheng-ming
    Computer Engineering. 2008, 34(7): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2008.07.001
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    The choice of the prior image models in image restoration is discussed in the Bayesian framework. The paper studies the properties of two classes of stochastic models for natural images, the generalized Gaussian model and the Markov random field, and constructs two corresponding cost functions of the image restoration problem. It surveys the edge-preserving abilities of the two classes of models, and proposes the conditions that the models need to satisfy to ensure the preservation of edges, and defines the edge-preserving prior. The theory of the sparse prior is considered, and it shows that the above two classes of models will be sparse under some constraints. The relationship between the edge-preserving prior and the sparse prior is analysed, and it concludes that an edge-preserving prior model is a sparse prior model. The work provides a criterion of the choice of a prior model in the process of image restoration. The numerical simulations show that a proper choice of prior image model can improve the restoration performance dramatically.
  • YANG De-zhi; XU Lu; ZHANG Jian-gang
    Computer Engineering. 2008, 34(7): 4-6,9. https://doi.org/10.3969/j.issn.1000-3428.2008.07.002
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    File system metadata requests may make up over 50% of all file system operations, which should be of critical importance in large scale distributed file system. This paper designs a metadata server cluster, named BWMMS, to provide metadata service in Blue Whale1000 network storage system. Due to its dynamic, logical and impartial rules, BWMMS can provide low latency and high scalability metadata services to system uses.
  • ZHOU Zhi-xiong; HE Hu; ZHANG Yan-jun; YANG Xu; SUN Yi-he
    Computer Engineering. 2008, 34(7): 7-9. https://doi.org/10.3969/j.issn.1000-3428.2008.07.003
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    Data transferring between clusters degrades the performance of clustered VLIW processors. This paper presents a novel two-dimension forced-directed schedule algorithm for Register-File-Connectivity Clustered Very Long Instruction Word (RFCC-VLIW) processors, in which the force expression varies as the cycle and cluster. Experimental results indicate that the schedule algorithm prevails against other ones for clustered VLIW processors when aiming to RFCC-VLIW architecture.
  • SUN Shi-bao; LIU Rui-xin; QIN Ke-yun
    Computer Engineering. 2008, 34(7): 10-13. https://doi.org/10.3969/j.issn.1000-3428.2008.07.004
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    This paper introduces covering rough sets and Ziarko’s variable precision rough model. Ziarko’s variable precision rough approximation operators are applied to covering approximation space. The concepts of β upper approximation, β lower approximation, β boundary region and β negative region of two kinds of variable precision covering rough set models are given by means of the error parameter β(0≤β<0.5). The basic properties of β upper approximation operator and β lower approximation operator in these two models are discussed. The relation of these two kinds of variable precision covering rough set model and the relation of these two models and other rough sets models are investigated.
  • LI Qian-mu; HOU Jun
    Computer Engineering. 2008, 34(7): 14-16. https://doi.org/10.3969/j.issn.1000-3428.2008.07.005
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    Dempster Rule based Network Fault Diagnosis(DRNFD) system for Ad hoc network troubleshooting is brought forward, in which “abnormal degree” is defined by the vector of probability and belief functions in a privileged process. A new formula based on Dempster rule is presented to decrease false positives. DRNFD reduces false positives effectively and can be applied to real-time fault diagnosis. Operational prototypical system demonstrates its feasibility and gets the effectiveness of real-time fault diagnosis.
  • LI Yun-feng; HE Da-ke
    Computer Engineering. 2008, 34(7): 17-18,2. https://doi.org/10.3969/j.issn.1000-3428.2008.07.006
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    Focusing on an electronic voting protocol without authority based on ElGamal encryption scheme. This paper points out that this protocol camnot guarantee the validity of the parameters sent out by voter for voting account. So the attacker has chance to change the voting result if he sends out a designed parameter at the fifth step. Three attack proposals towards Su-protocol are given, including fairness attack, accuracy attack and privacy attack.
  • GAO Mao-ting; WANG Zheng-ou
    Computer Engineering. 2008, 34(7): 19-22. https://doi.org/10.3969/j.issn.1000-3428.2008.07.007
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    Document Index Graph(DIG) is a kind of phrase-based graph structure text feature representation model, which is able to express text feature information more completely and exactly to realize incremental text clustering and information processing. Based on DIG, document similarity additive and multiplicative strategy are proposed, document similarity is adjusted by a set of transform function, distinguishability between documents is strengthened, and performance of text clustering and classification are improved. Experiments demonstrate the efficiency of the methods.
  • SUN Ting; LU Dong-xin; YANG Yong-tian
    Computer Engineering. 2008, 34(7): 23-25. https://doi.org/10.3969/j.issn.1000-3428.2008.07.008
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    After the discussion of cluster organization and its formalization, a new optimized wireless sensor networks routing algorithm is proposed, which uses convergence degree concept during the foundation of cluster head. It mainly analyses the election of the cluster head, cluster building/re-building and cluster’s self-recovery mechanism. Compared with the traditional random algorithm and least ID algorithm, the simulation shows that new algorithm has a lower overlap, balances the network nodes energy depletion and prolongs the lifetime of whole networks.
  • ZHANG Ming; BI Du-yan
    Computer Engineering. 2008, 34(7): 26-28. https://doi.org/10.3969/j.issn.1000-3428.2008.07.009
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    This paper proposes a novel and simple fast Block-Matching Algorithm (BMA), called Adaptive Variety-Pattern Search (AVPS), which efficiently utilizes the high relation of adjacently block’s motion vectors. The algorithm adopts a series of skills, which are composed of prediction of initial search point, effective half-stop criteria, adaptive search pattern and auxiliary search points. Extensive experiments conducted based on the H.264 encoding platform show that the proposed AVPS can reduce the computational complexity by 16%~33% and 30%~50% compared with the UMHexagonS and EPZS, while maintaining similar PSNR and bit rate.
  • ZHANG Xiao-miao; SHANG Yang; YU Qi-feng
    Computer Engineering. 2008, 34(7): 29-31,3. https://doi.org/10.3969/j.issn.1000-3428.2008.07.010
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    In order to measure the ego motion of the monocular zooming camera, this paper presents a method named Para-Calibration measurement. When the flying platform is landing, the downward-looking monocular camera fixed to it keeps shooting the static landing plane, on which there are several feature points with world coordinates known. On this condition, the method presented can calculate the equivalent focal lengths and the 6 DOF position relative to the landing plane by one frame. Then, the velocity of ego motion can be estimated by combining sequential frames and the landing motion will be drawn. Experimental results show that the method is practicable and efficient.
  • ZHOU Pu-cheng; HAN Yu-sheng; XUE Mo-gen; HONG Bing-rong
    Computer Engineering. 2008, 34(7): 32-34. https://doi.org/10.3969/j.issn.1000-3428.2008.07.011
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    To solve the problem that a group of robots cooperatively pursue a target robot, based on motor schema-based reactive control architecture, four basic behaviors including move-to-goal, avoid-obstacle, avoid-teammate and shrink-surround are designed for each pursuing robot. To prevent each robot from deadlock state, random-wander behavior is introduced. Through vector synthesis of these basic behaviors and local interaction among robots, multi-robot collaborative behavior is achieved. The validity of the approach is verified by simulation experiments.
  • ZHOU Zheng; LI Jian; ZHANG Jun
    Computer Engineering. 2008, 34(7): 35-37. https://doi.org/10.3969/j.issn.1000-3428.2008.07.012
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    A model to measure the trustworthiness of subject’s behaviors is presented, and a frame to realize the model function is given. The principle to measure the trustworthiness of subject’s behaviors is expatiated, which controls suspicious behavior of legal programs and codes. According to the trustworthiness measured out by the model, it can forbid the running of illegal programs and codes, and the unauthorized access of legal programs and codes. It discusses how to get a trade-off between security and practicability with certain security threshold values.
  • WEN Ming; HAN Hui; WANG Lei; ZHUO Qing; WANG Wen-yuan
    Computer Engineering. 2008, 34(7): 38-40. https://doi.org/10.3969/j.issn.1000-3428.2008.07.013
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    This paper presents a novel method for object recognition based on part vocabulary. A vocabulary of object parts is automatically constructed from sample images of the object class by AdaBoost. Images are represented by using parts from the vocabulary. Based on it, Sparse Network of Winnows (SNoW) learning architecture is employed to learn to recognize the instances of the object class. Experimental results show that the method achieves high recognition accuracy on different data sets, and it is robust to partial occlusion and background clutter.
  • LI Pei-feng; ZHU Qiao-ming; QIAN Pei-de
    Computer Engineering. 2008, 34(7): 41-43,4. https://doi.org/10.3969/j.issn.1000-3428.2008.07.014
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    Nowadays, it’s hard to build a large-scale corpus with low cost and short period. A new approach is provided to build that on Web. It mainly focuses on how to build a large-scale corpus on Web and then how to correct the mistakes in the corpus. The language materials are collected and processed based on grid and Wiki. The untrustworthy language materials in the corpus are picked out to be checked manually on Wiki according to their trustworthiness. After the check finishes, the approach calculates the trustworthiness of each checked result and selects ones with highest trustworthiness as the correct result.
  • ZHANG Yu-ping; LI Xin; CHEN Huai-li; JIANG Shou-wei
    Computer Engineering. 2008, 34(7): 44-46. https://doi.org/10.3969/j.issn.1000-3428.2008.07.015
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    A novel scheme using the Transitive Closure Graph(TCG) representation is proposed to explore the symmetry solution space in the placement problem, which usually abounds in complex constraints. General-symmetric-feasibility and special-symmetric-feasibility conditions of a TCG representation are used. The proposed TCG symmetry placement algorithm has been tested using several skins of trim. Experimental results show its superiority to both the conventional absolute coordinate representation and the symmetry sequence-pair approaches.
  • Software Technology and Database
  • ZHANG Chen-xi; LI Jiang-feng; LIU Yi; ZHAO Wei-dong
    Computer Engineering. 2008, 34(7): 47-49,5. https://doi.org/10.3969/j.issn.1000-3428.2008.07.016
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    User management system is an important part in Web application system and a large-scale software system. In the existed user management system, a role, which is a set of authorities, does not involve scope. It is a conception in a one-dimensional space. A conception of two-dimensional role is given, which is in a two-dimensional space. A role is a binary set composed of authorities and scopes. A universal user management model based on user roles is constructed. Design and implementation of a universal user management system is achieved. It can satisfy requirements of modern Web application systems and large scale software systems in multiply levels and spaces towards user privilege.
  • FENG Nan; LI Min-qiang; KOU Ji-song; FANG De-ying
    Computer Engineering. 2008, 34(7): 50-52. https://doi.org/10.3969/j.issn.1000-3428.2008.07.017
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    An improved risk evaluation model in software project investment is presented. Based on the evaluation index system, the model utilizes factor analysis way to decrease dimension of sample data for simplifying problem. In the modeling of Neural Network (NN), an optimization algorithm based on the principle of golden section to design the number of hidden layer nodes is utilized for increasing the precision of risk evaluation. The model can accomplish the work of risk evaluation in software project investment by verifying the sample data of risk evaluation.
  • ZHAO Ze-yu; YAN Hua
    Computer Engineering. 2008, 34(7): 53-55. https://doi.org/10.3969/j.issn.1000-3428.2008.07.018
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    Large growth in the number of URLs makes the indexes of Internet content filtering systems overstaffed. A pruning method of index model based on CPat-Tree is put forward. The method compares the similarity of keys of CPat-Tree and classifies them into clusters. After combination, the storage of arrays is largely reduced and query efficiency is improved. Due to the relevance between the similarity of keys and the effect of pruning method, the method is proved with good expansibility.
  • LIN Chao; ZHAO Peng-peng; CUI Zhi-ming
    Computer Engineering. 2008, 34(7): 56-58. https://doi.org/10.3969/j.issn.1000-3428.2008.07.019
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    A lot of pages on Internet are generated dynamically by the back-end databases, which can not be reached by the traditional search engines called Deep Web. This paper proposes an algorithm of Deep Web sources focused crawling. When evaluating the importance of hyperlinks, it takes into consideration relevance among page, topic, and link-related information. Experiments indicate that this method is effective.
  • LIU Lei; ZHAO Rong-cai; GONG Xue-rong
    Computer Engineering. 2008, 34(7): 59-60,6. https://doi.org/10.3969/j.issn.1000-3428.2008.07.020
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    The parallel code that the compiler generates automatically leads to code expansion and unnecessary running time increase if it includes too much redundant code. This paper presents an optimization technique to eliminate redundant communication code by using Fourier-Motzkin- elimination algorithm for linear inequalities of computation decompositions and data decomposition. The test results show that the technique is able to reduce the size of the code by 10 to 30 percent compared with the original code, and the speedup achieves 1.12 on average using the same number of processors.
  • HAN Xiao-kun; JIANG Lie-hui; YIN Qin; CHEN Liang; ZHOU Bo
    Computer Engineering. 2008, 34(7): 61-63. https://doi.org/10.3969/j.issn.1000-3428.2008.07.021
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    Instruction set simulator is a powerful tool for chip design evaluation and software converse project development. In this paper, the strategy of interpretative simulation is applied, and the design and implementation of retargetable instruction set simulator are discussed. A solution of virtual instruction set is presented, which can be used among a series of processors. To improve the performance, some optimization methods are introduced.
  • JIANG Fan; PANG Jian-min; ZHAO Rong-cai; REN Hua
    Computer Engineering. 2008, 34(7): 64-66. https://doi.org/10.3969/j.issn.1000-3428.2008.07.022
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    Precise array data-flow analysis is an important step in parallelizing compiler technique. Stanford University presents an algorithm to calculate an LWT for a single pair of read and write statements. This paper researches and implements an LWT intersect algorithm in order to analyze precise data dependence relationship with multiple writes and common read. The result of this algorithm eliminates a lot of redundant information and improves the precise array data-flow analysis technique.
  • YE Dun-fan; ZHOU Fei-fan
    Computer Engineering. 2008, 34(7): 67-69. https://doi.org/10.3969/j.issn.1000-3428.2008.07.023
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    This paper describes the design of a Wireless Sensor Network(WSN) nodes local data storage system, through the establishment of the logical structure of the storage resources for a reasonable district and it maximizes utilization. A data storage method is proposed which does rapid address positioning, and it effectively reduces the storage medium frequency of visits, and energy loss of the storage media visits. It also adds a safety detection mechanism in the process of storage to ensure consistency of data.
  • ZHU Zong-qian; JI Hao; YANG Dong-min
    Computer Engineering. 2008, 34(7): 70-72. https://doi.org/10.3969/j.issn.1000-3428.2008.07.024
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    Aiming at questions about the difficulty of data acquisition of risk estimation information of ERP implementation, the paper builds the model of Web mining in risk estimation information of ERP implementation, on the base of utilizing massive Web information, using methods of Web information mining and analyzing classification of risk estimation information of ERP implementation, discusses the key technologies of the model, and gives a typical example.
  • LIU Li-jia; SHENG Ye-hua; LU Ming-yue; CHEN Min; HUANG Yun
    Computer Engineering. 2008, 34(7): 73-75. https://doi.org/10.3969/j.issn.1000-3428.2008.07.025
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    In geographic information system, the best path searching is the basis of other network analysis. Based on the research results in the field of the best path, this paper puts forward an efficient best path searching algorithm based on bidirectional semi-order net to solve the best path searching of two assigned nodes. And this algorithm is evaluated for its practical efficiency with several computing examples. The application prospect and advance of the algorithm are discussed.
  • ZHAO Yan-juan; LI lian; SU Wei; LI Guan-yu
    Computer Engineering. 2008, 34(7): 76-78. https://doi.org/10.3969/j.issn.1000-3428.2008.07.026
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    To make up for shortage of traditional approach for resolving mathematical expressions on Web, a MathML-based mathematical expressions editor named MathEdit is presented. It is a totally Web-based environment for mathematical expressions processing and transmit, which is implemented in standard JavaScript and DOM, and makes use of browser support for MathML display. The architecture, implementation, flexibility and extensibility of MathEdit are discussed.
  • WANG Dong; SUN Bin
    Computer Engineering. 2008, 34(7): 79-80,8. https://doi.org/10.3969/j.issn.1000-3428.2008.07.027
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    This article profits from Ajax and DataWindow, the technical style, carries on the induction to MVC using the model and the J2EE correlation technology, then summarizes a typical DataWindow model. It analyzes XMLHttpRequest, the service vessel object, the abstract of service, the backstage control, the URL parameter synthesis and so on. Then it builds the B/S application model with high efficiency, strong transplantation and quick response.
  • LIU Fei; HUANG Xuan-jing; WU Li-de
    Computer Engineering. 2008, 34(7): 81-83. https://doi.org/10.3969/j.issn.1000-3428.2008.07.028
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    Thematic terms extraction is one of the hot topics in the field of information retrieval, and in tight relationship with a variety of data mining tasks. This paper presents an approach for extracting thematic terms based on association rules, which include both keyphrases and related terms. Based on keyphrase extraction, related terms could be used in extended search and related information retrieval, as well as providing users with a better understanding of the topic. Experimental results show that the method is effective in extracting both keyphrases and related terms.
  • JIANG Meng-qi; ZHANG Yun-quan; SONG Gang; LI Yu-cheng
    Computer Engineering. 2008, 34(7): 84-86,1. https://doi.org/10.3969/j.issn.1000-3428.2008.07.029
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    This paper analyses the implementation mechanism of GOTOBLAS library, especially the high performance implementation of its General Matrix-matrix Multiplication(GEMM) routines, and shows how to achieve high performance. It can be concluded that the effects of hierarchical memory on application performance are brought into the design of new computational models. Experimental results verifies the high performance of GOTOBLAS compared with public domain available BLAS, and testifies the important effect of hierarchical memory on algorithm performance.
  • Networks and Communications
  • WANG Quan-li; FU Yan
    Computer Engineering. 2008, 34(7): 87-88,9. https://doi.org/10.3969/j.issn.1000-3428.2008.07.030
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    Since homogeneous wireless network technology is no longer suitable for the development of heterogeneous networks, the future wireless communication network is going to be a heterogeneous network environment which combines different wireless technology and network architectures. This paper proposes a new mobility management scheme based on Host Identity Protocol (HIP) and Session Initiation Protocol (SIP). The hybrid model HIP-SIP scheme is for all services, and the IPsec scheme in the model TCP-HIP is used to ensure communication in security.
  • LIU Zhi; ZHANG Yun
    Computer Engineering. 2008, 34(7): 89-91. https://doi.org/10.3969/j.issn.1000-3428.2008.07.031
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    In the development of high speed communication network, the burst state and diversity of network traffic make it difficult to achieve QoS of network. This paper proposes a network adaptive congestion control method, where the fuzzy reference model mechanism is integrated to improve the adaptive performance of AQM in the burst network. The control system is integrated with the reference model to implement the fuzzy back-loop inference learning algorithm, and adjust the control behavior of the primary control channel following the network burst state. Simulation results show that the proposed method improves the performance of the congestion control system greatly, and makes a better trade-off between the adaptive performance and real-time performance.
  • XUE Xiao-ping; ZHANG Si-dong; WANG Xiao-ping; CAO Xiao-ning
    Computer Engineering. 2008, 34(7): 92-94,9. https://doi.org/10.3969/j.issn.1000-3428.2008.07.032
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    Combing with the evolution and advances in the data quality and reliability research in RFID network, this paper classifies and analyzes various technologies for improving RFID data reliability and quality, including smoothing and arbitration, pipeline, estimation-based method, integrality-based restraint method, etc. When designing RFID system with high quality for meeting with several requirements, some current data cleaning technologies are properly chosen and fitted together adaptively to improve RFID reading reliability.
  • WEI Nuo; GUO Qiang; LI Chun-jie; LIU Rui-xia; KONG Xiang-long
    Computer Engineering. 2008, 34(7): 95-97. https://doi.org/10.3969/j.issn.1000-3428.2008.07.033
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    The existing algorithms of sensor networks is analyzed and compared. In order to eliminate the effects on synchronization errors which is made by the clock skew, an event-triggered time synchronization algorithm based on skew calculation is proposed. In the algorithm, when an event occurs, each related node calculates the clock skew by linear regression, then estimates round-trip delay and synchronization difference by exchanging synchronization signals. Simulation result indicates that the algorithm can reach a desired accuracy.
  • LI Ming; ZHOU Jie; GAO Xue-song; LIU Hui; LIU Shu-ying
    Computer Engineering. 2008, 34(7): 98-100. https://doi.org/10.3969/j.issn.1000-3428.2008.07.034
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    An improved approach of DSMCast is presented. In the approach, only the replicating and forwarding status information for the core nodes are encapsulated into the packets’ extended header, and the edge nodes should maintain local multicast informations. Core routers are simplified as it is in DSMCast, and the size of the extended header of multicast packets will descend dramatically. As a result, the utility ratio of each packet will be higher than DSMCast approach. According to the simulating result, the approach behaves better than DSMCast.
  • LI Pu-cong; WEI Wen-hong;
    Computer Engineering. 2008, 34(7): 101-103. https://doi.org/10.3969/j.issn.1000-3428.2008.07.035
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    Peer-to-Peer overlay networks have various features such as robust wide area routing, efficient search, and selection of nearby peers. This paper introduces a new network model——CayNET that supports grouping, and defines a DHT protocol——CayNET DHT in the network model, puts forward its topology, describes progress of adding and exiting in CayNET DHT. Experimental results show that the protocol is effective.
  • YANG Liu; LI Zhen-yu; DU Ning; ZHANG Da-fang; XIE Gao-gang
    Computer Engineering. 2008, 34(7): 104-106. https://doi.org/10.3969/j.issn.1000-3428.2008.07.036
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    With the rapid growth of Internet scale and the development of IPv6 protocol, network management tools for next generation Internet become more and more important. This paper designs an IPv4/IPv6 compatible SNMP communication mechanism, and a topology discovery algorithm based on SNMP. On this basis, a network management system for next generation Internet is designed and implemented. The system mainly consists of three modules: topology discovery module, network performance analysis module and fault management module, respectively. This system has been applied in practical network environment successfully.
  • JIA Guan-xin; YANG Bo; PENG Li-zhi
    Computer Engineering. 2008, 34(7): 107-109. https://doi.org/10.3969/j.issn.1000-3428.2008.07.037
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    Because of the great quantity of network traffic data, the first problem for network traffic engineering is how to store traffic data and retrieve these data efficiently. This paper presents a design of how to store and retrieve NetFlow data in distributed multi-level directory. An optimization blueprint is discussed whose objective is to store and retrieve NetFlow data efficiently. This paper also brings out the frame of this system and part of data structures which are used to retrieve data. How to work with these data structures is also presented.
  • WANG Yu-jian; BAO You-wen; TONG Jian-xin; YUAN Jia-zheng
    Computer Engineering. 2008, 34(7): 110-112. https://doi.org/10.3969/j.issn.1000-3428.2008.07.038
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    On the basis of analyzing the characteristics and defects of CORBA and mobile Agent technologies, a design method of network management system based on CORBA and mobile Agent is proposed. In the system model, Java virtual machine is acted as run platform, ORB is acted as communication service of lower layer, and KQML is acted as communication language. Considering that the performance affections of the two modes to network scale are different, in the system CORBA object and mobile Agent is used respectively in different network management tasks. The performance evaluation and experimental results show that the performance of this system is better than network management system based on CORBA or mobile Agent.
  • YUE Shi-cheng; WANG Pei-kang
    Computer Engineering. 2008, 34(7): 113-114,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.039
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    The nodes have limited available power in wireless sensor networks. In view of the trait, this paper analyzes leach protocols, and an energy-efficient routing algorithm is proposed and evaluated in which the cluster formation is controlled by the residual energy and the number of cluster members. In addition, the cluster heads take hierarchical routing scheme to communicate with the base station. Simulations show that the new algorithm provides longer lifetime than leach protocols.
  • LI Shan-liang; ; HUANG Liu-sheng; WU Jun-min; XU Hong-li;
    Computer Engineering. 2008, 34(7): 115-117. https://doi.org/10.3969/j.issn.1000-3428.2008.07.040
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    Due to the fact that current localization algorithms have a very poor performance when unknown nodes are near the border of the area, this paper proposes a localization algorithm merely based on connectivity information called RMBC. Simple and redundant notes are added to improve the performance of the algorithm and adapt the range and deployment of redundant motes for further analysis. In addition, a new metric to evaluate localization algorithms called Coverage of Localization(CoL) is designed. The simulation results indicate that RMBC significantly outperforms Centroid and APIT in CoL and compared with Centroid, RMBC decreases mean locationerror by 32.7% and maximum location error by 44.8%.
  • ZHU Yu-hong; XU Chang-qing
    Computer Engineering. 2008, 34(7): 118-119,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.041
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    Accurate coverage prediction and network capacity simulation can significantly drive down operator’s overall CAPEX and OPEX, which makes the Wireless Local Area Network(WLAN) application more cost-effective. This paper focuses on the suitable radio propagation module of 2.4 GHz WLAN signal that has been tuned by a set of field measured data. Simulation of network capacity derives from both the theoretical calculation and data that is measured in real application scenario. The paper dicusses the WLAN protocol only refers to IEEE802.11b.
  • WANG Xiao-nan; QIAN Huan-yan
    Computer Engineering. 2008, 34(7): 120-122. https://doi.org/10.3969/j.issn.1000-3428.2008.07.042
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    This paper proposes a new kind of Anycast communication model in mobile IP network. This model can dynamically select the optimal Anycast member according to the current status of network congestion, achieve dynamic Anycast group, allow Anycast members to freely leave and join Anycast group, and solve the existing scalability problem. In addition, this model accomplishes the distributed maintenance and transaction of Anycast service request and Anycast tree’s information so it fulfills the load balance. Experimental data in IPv6 simulation demonstrate that the TRT of one kind of service (for example, file downloading) acquired through this communication model is smaller than the one through the current mobile IP communication model.
  • WANG Wen-zheng; ZHOU Jing-lun; LUO Peng-cheng
    Computer Engineering. 2008, 34(7): 123-125. https://doi.org/10.3969/j.issn.1000-3428.2008.07.043
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    In order to urge the standardization of the network design of tactical data link network, this paper analyzes the characteristics and the topological structure of tactical data link network and puts forward a kind of tactical data link network architecture. The network architecture has a two-dimentional structure. Through cross level design, it has the strong adaptability. The feasibility and validity of the architecture is testified by analyzing the flow of data in Link16.
  • Security Technology
  • HONG Zheng; WU Li-fa; WANG Yuan-yuan
    Computer Engineering. 2008, 34(7): 126-128. https://doi.org/10.3969/j.issn.1000-3428.2008.07.044
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    Based on negative selection mechanism of the immune system, this paper proposes a worm containment model. By monitoring abnormal program behavior, the model effectively detects worms and makes reaction. The reaction policy contains worm propagation and allows the majority of normal traffic to proceed. Negative selection is used to filter service requests which the worm host sends out, and according to worm properties, hosts cooperate to determine and contain the services which the worm attacks. Experimental results indicate the model can detect and contain classical worms as well as emerging stealthy worms such as topological worms.
  • WANG Jie; ZHANG Jian-zhong
    Computer Engineering. 2008, 34(7): 129-130,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.045
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    This paper proposes a threshold shared verification signature encryption scheme which based on elliptic curve, in which any t among n verifiers can verify the validness of signature, otherwise it cannot. The scheme integrates digital signature scheme with public key cryptography system. Compared with proposed threshold shared verification signature encryption scheme, it has higher secrecy of data transmission, requires shorter secret key distance and smaller communication cost, performs efficiently and be able to prevent verifier cheat, etc.
  • LU Feng; ZHENG Kang-feng; NIU Xin-xin; YANG Yi-xian
    Computer Engineering. 2008, 34(7): 131-133,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.046
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    The paper proposes two schemes which enhances the performance of PPM in following aspects. Because of ingenious design, the schemes can be used to tackle large-scale DDoS. And due to adopting varational probabilistic packet marking, they can recognize and eliminate spoofed marking inscribed by the attacker intentionally. By recording the state of IP address transmission in router and transmiting the packets fragments in order, the schemes can significantly reduce the number of packets required for path reconstruction.
  • PENG Jun-hao; XU Guo-ai; ZHU Zhen-rong; YANG Yi-xian
    Computer Engineering. 2008, 34(7): 134-136. https://doi.org/10.3969/j.issn.1000-3428.2008.07.047
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    SIRS worm propagation model is provided and its stability is anal sized. When R0<1, worm will disappear finally. When R0>1, “local plague” of worm will appear. The model fits well with worm data from CAIDA when testing the model with these data. At the same time, the influence on worm control of different policies is analyzed, such as host losing immunity to worm, shutting down host or cutting off network timely when host is infected, and vaccinating actively.
  • HAN Jun; HUAI Xiao-yong; ZHAO Chen
    Computer Engineering. 2008, 34(7): 137-138,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.048
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Most current Web services discovery methods rely on centralized UDDI registries. Due to the security and area, organizations usually build distributed private registries and enforce access control mechanisms. The registered and trusted people can browse the information of services they have permissions to access. A RBAC model for Web services discovery phase named RBAC4WSD is proposed. Discovery agencies are designed to perform access control on service requestors upon security policies specified by service providers. In terms of a scenario of distributed document service within a multinational company, a prototype system is described.
  • CHEN Jian; ZENG Fan-ping
    Computer Engineering. 2008, 34(7): 139-141. https://doi.org/10.3969/j.issn.1000-3428.2008.07.049
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    Wormhole attack is a severe attack in Ad hoc network. In the wormhole attack, two malicious nodes are sent and re-transmit packet received at one end of the wormhole to the other end. In this way, wormhole attack disrupts the network routing by generating shortest path. This paper proposes a novel end-to-end wormhole detection method based on trust model.
  • ZHANG Jun
    Computer Engineering. 2008, 34(7): 142-144. https://doi.org/10.3969/j.issn.1000-3428.2008.07.050
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    This paper proposes a novel image steganography based on relativity between images. The secret image and cover image are decomposed by wavelet transform, and the wavelet domain of the secret image is divided into blocks. For each block, multiresolution block watching scheme is utilized to search for its similarity block in the wavelet domain of the cover image. Then, the replacement image of the secret image is calculated according to the similarity block, and it is coded by zero tree wavelet coding method. The coded bit information and map rules of the similarity block are embedded into the least significant bits of the cover image. The experimental results demonstrate the proposed method is superior to relative methods in the literature. Especially, the quality of the extracted secret image is improved by 3 dB at least when the secret image is typical image of the F-16 plane.
  • CHEN Guo-qi; HUANG Jun
    Computer Engineering. 2008, 34(7): 145-147,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.051
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    A consistency checking-based proxy-report schemes rooted at the BS is introduced, which uses proxy reports to verify the accuracy of data reports sent by a CH to the BS. Proxy reports are periodically sent along non-primary paths, enabling the BS to detect any tampering or dropping of the data reports by malicious nodes on the primary paths.
  • ZHANG Li-li; CAO Tian-jie; TANG Li-juan
    Computer Engineering. 2008, 34(7): 148-150. https://doi.org/10.3969/j.issn.1000-3428.2008.07.052
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    It is an important network security problem that how to solve Denial of Service(DoS) attack. Several countermeasures are proposed for it in the literature, among which, the Probabilistic Packet Marking(PPM) scheme developed by Savage et al is promising. This paper improves PPM. Compared with PPM, it only needs four efficient fragments to build one edge, and is more efficient to reconstruct the attack path. Analysis and experiments show the effect of the scheme.
  • LIANG Kun; ZENG Fan-ping
    Computer Engineering. 2008, 34(7): 151-153. https://doi.org/10.3969/j.issn.1000-3428.2008.07.053
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    Mobile Ad hoc Network(MANET) is a multi-hop temporary communication network of mobile nodes equipped with wireless transmitters and receivers without the aid of any established infrastructure. Intruder identification is important in routing security of the entire network. This paper analyzes current solutions and proposes a protocol to solve false destination sequence attack in AODV by introducing an algorithm of reputation rating updating. Simulation results show that the network performance and identification precision are greatly improved.
  • TIAN Xu; LIU Ren-jin; CHEN Ming-hua
    Computer Engineering. 2008, 34(7): 154-156. https://doi.org/10.3969/j.issn.1000-3428.2008.07.054
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    A new mobile routing protocol using Hash function and iterative method is proposed in this paper for solving mobile agent routing security problems. User hosts are able to ensure routing information transporting to the others securely by the unidirectional feature of Hash function, and verify each other by the iteration of Hash function. The analysis shows that the computational complexity of the routing protocol is drastically reduced, especially in the condition of transporting large number of data. The normal and the strand space models are adopted to prove the security of the protocol.
  • WANG Juan; GUO Yong-chong; WANG Qiang
    Computer Engineering. 2008, 34(7): 157-159,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.055
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    Communication technologies of Trojan horses are studied, and a communication model using WebMail system as a broker is proposed. With the model, the controlled end of the Trojan horse accesses WebMail systems in Internet by HTTP and can easily pass through the firewall of LAN. The controller does not need public or fixed IP addresses, so it can work well in places like cybercafe. To validate the model and evaluate its hazard, a prototype Trojan horse is designed. Some advices on protection against this kind of Trogan horse.
  • LIU Wei-peng; HU Jun; LV Hui-jun; LIU Yi
    Computer Engineering. 2008, 34(7): 160-162. https://doi.org/10.3969/j.issn.1000-3428.2008.07.056
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    This paper analyses the main design idea of Linux Security Module(LSM) and the problem of the intrinsic access control mechanism of Linux executable program, and discusses the design of Mandatory Access Control(MAC) mechanism of executable program based on LSM. As the demonstration, it implements a MAC system prototype based on Linux kernel 2.6.11. The illumination that how to implement MAC of executable program in operating system is given.
  • WANG Jian-yu; ZHANG Lu-guo
    Computer Engineering. 2008, 34(7): 163-164,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.057
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    According to the traditional method, the encryption/decryption of AES are designed separately, and it consumes lots of hardware resources. In this paper, on the foundation of analyzing the encryption/decryption of AES, the implementation method of each part about the algorithm is introduced. After analysis, the commonness of encryption/decryption is given, and reconfigurable design for the algorithm is presented. Simulation and validation on FPGA shows that this design can reduce the area cost greatly compared with other traditional design.
  • WANG Xiao-ming
    Computer Engineering. 2008, 34(7): 165-167. https://doi.org/10.3969/j.issn.1000-3428.2008.07.058
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    The paper proposes a secure access control scheme for P2P(Peer-to-Peer) networks and explores the use of the two layers of access control mechanisms to provide security services such as joining the P2P network, using P2P network’s resource etc. Firstly, a new member is audited if he can enter into P2P network based on secure requirements and the members undesired for P2P network are eliminated. Secondly, the member ‘s trusted value is rated in P2P network and his access right to P2P network’s resource is assigned based on trusted access control mechanism. The scheme can revoke out the malicious members from P2P network. Therefore the scheme can realize secure access control for P2P network.
  • LI Yi; ZHANG Shao-wu; ZHUANG Yuan-yang; CAO Yong-gang
    Computer Engineering. 2008, 34(7): 168-170. https://doi.org/10.3969/j.issn.1000-3428.2008.07.059
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to resolve network communication anonymity problem, Zhangsheng et al. presented a one-off public key scheme using identity-based cryptography but the scheme can not ensure the anonymity of the receiver and the signature process can be counterfeited, its security cannot be ensured. This paper constructs a new one-off public key scheme based on the conception of signcryption, the scheme is effective and satisfies synchronously the anonymity of the two parties in the communication.
  • WANG Ji; LUO An; ZHANG Jing; XU Ming
    Computer Engineering. 2008, 34(7): 171-172,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.060
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    In order to avoid aggrieving the legality benefit of a hydraulic-brick-machine manufacturing-enterprise, a new PLC control system with authentication function based on FPGA is presented after the analysis of former control system in this paper. The new control system is introduced encryption board between the communication cable and PLC. The base program in the core which is the limited-state-machine is exploited by the use of VHDL. The stability, reliability and security of the control system is validated through the application to industry application.
  • HU Yu-xiang; LAN Ju-long; CHENG Dong-nian; WANG Hao-xue
    Computer Engineering. 2008, 34(7): 173-175. https://doi.org/10.3969/j.issn.1000-3428.2008.07.061
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    Rethinking the requirements of next generation trustworthy network, this paper uses the idea of separate policy management from data processing for reference, and puts forward a design of security mechanism based on specific chips with distributed implementation and centralized management for high-performance core router. System test proves the correctness and feasibility of this design. It provides security protection with high performance on the foundation of high reliability, and meets the basic requirements of real-time encryption/decryption in next generation backbone.
  • Artificial Intelligence and Recognition Technology
  • HUANG Hui-xian; CHEN Zi-bin
    Computer Engineering. 2008, 34(7): 176-177,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.062
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A new Particle Swarm Optimization(PSO) arithmetic based on hybrid information is presented, which covers the advantages to get available information from the best individual and the worst individual. Adaptive mutation arithmetic is also used to adjust the searching direction of nonlinear function problem, in which the speed weight ratio is mutated according to fitness of the objective function. Simulation results show that the nonlinear function problems can be solved with greater searching efficiency and better solution accuracy.
  • YE Wen; ZHU Ai-hong; FAN Hong-da
    Computer Engineering. 2008, 34(7): 178-180. https://doi.org/10.3969/j.issn.1000-3428.2008.07.063
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    For the calculation complexity and the convergence in Unmanned Combat Aerial Vehicle(UCAV) path planning, based on the study on the principles of traditional Particle Swarm Optimization(PSO), mutation operator is presented during the searching process in order to prevent from getting into the local optimum. This paper uses a group of sine waves to construct a parameter, and restricts the number and swing of sine waves. The optimal route can pass the start point and the target point precisely, and is feasible applying to UCAV. Simulation result shows that the method is effective.
  • LIN Chuan; FENG Quan-yuan
    Computer Engineering. 2008, 34(7): 181-183. https://doi.org/10.3969/j.issn.1000-3428.2008.07.064
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    Based on the idea of specialization and cooperation, an adaptive Particle Swarm Optimization(PSO) algorithm is proposed. In the new algorithm, different particles are assigned specific tasks. Better particles are given larger inertial weights, while worse ones are given smaller inertial weights. And the particle’s acceleration coefficients are adaptively adjusted according to its inertial weight. Besides, the personal best position and global best position in standard PSO algorithm are respectively replaced by the weighted mean of some relevant personal best positions. These strategies improve the PSO algorithm at the aspects of diversity and the balance of exploration and exploitation. The efficiency of the new algorithm is verified by the simulation results of five classical test functions and the comparison with other PSO algorithms.
  • WANG Wei; WANG Rong-jie; HU Qing
    Computer Engineering. 2008, 34(7): 184-185,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.065
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A new method of fault diagnosis distinguishing based on PCA-neural network is raised. It uses PCA theory to extract the main element from the fault sample data, realizes optimum compression of fault sample data, simplifies structure of neural network classifier in fault diagnosis, and enhances classification speed and precision. The results of power electronic circuit experiment show that the method can decrease the number of the network input nerve cells effectively, and enhance study efficiency and diagnosis accuracy. The way has very good fault distinguishing ability and vast prospect.
  • LIU Xiao-xiong; ZHANG Wei-guo; LI Guang-wen
    Computer Engineering. 2008, 34(7): 186-188. https://doi.org/10.3969/j.issn.1000-3428.2008.07.066
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Fault diagnosis is very important for enhancing the safety and reliability of flight control sys tem. To improve the learning efficiency and stability of neural network, an improved learning algorithm for the adaptive Radio Basis Function(RBF) neural network is proposed. Network parameter is optimized by efficient hybrid conjugate gradient optimization algorithm. The scheme is illustrated through simulations applying the flight control system of a fighter. Simulation results show that fault identification is achieved.
  • ZHANG Qian; YANG Jing; JIA Ding-ding
    Computer Engineering. 2008, 34(7): 189-190,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.067
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    Wavelet transform is introduced into registration due to its multi-resolution property. When the low-resolution images are registered, a hybrid algorithm of Particle Swarm Optimization(PSO) and simplex is used. While registering higher-resolution images, it only uses simplex. PSO excels in global searching while simplex excels in local searching. When used together, a more accurate result can be got. Meanwhile, a smaller searching space can be reached using wavelet transform which speeds up registration.
  • SHU Wan-neng
    Computer Engineering. 2008, 34(7): 191-193. https://doi.org/10.3969/j.issn.1000-3428.2008.07.068
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The heterogeneity and distribution of Internet leads to the large-scale sharing of resources very difficult, so most education resources can not be reused in traditional campus network. The grid technologies provide a chance to resolve these problems. By analyzing the current status of campus network and grid technologies, this paper presents job scheduling model and designs a job scheduling method based on Quantum Genetic Algorithm(QGA) in campus grid. By adopting the qubit chromosome as a representation, QGA can represent a linear superposition of solution due to its probabilistic representation. It is is superior to genetic algorithm simultaneously.
  • WANG Dong-dong; ZHOU Yong-quan
    Computer Engineering. 2008, 34(7): 194-196. https://doi.org/10.3969/j.issn.1000-3428.2008.07.069
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    The theorem used to judge whether all roots of a polynomial are in unit circle is put forward. To transform the polynomial by the transforming parameter, and Artificial Fish School Algorithm(AFSA) for finding the minimum value of the transforming parameter which makes all the roots of the polynomial in unit circle based on the judging theorem is given. It is Artificial Fish School Algorithm for finding the largest module of roots of polynomial. Several computer simulation results show that using this algorithm to find the largest module of roots of polynomial is more efficient and feasible, and the convergent speed and the accuracy of result is higher.
  • GE Hong-wei; PENG Zhen-yu
    Computer Engineering. 2008, 34(7): 197-199. https://doi.org/10.3969/j.issn.1000-3428.2008.07.070
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    In order to solve the problem of low output caused by the defects in VLSI manufacture, A redundant repair method is given. The problem of arrays reconfiguration is translated into the maximum independent set problem of contradiction graph. An ant colony optimization algorithm for redundancy VLSI array reconfiguration is proposed on the basis of contradiction graph of fault element. Experimental results show that compared with the standard genetic algorithm and Hopfield neural network algorithm, ant colony optimization algorithm of array reconfiguration for solving redundancy VLSI using single track switches is proved to be a simple and effective method.
  • YUAN Xiao-feng; XU Hua-long; CHEN Shu-hong
    Computer Engineering. 2008, 34(7): 200-202. https://doi.org/10.3969/j.issn.1000-3428.2008.07.071
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    To solve the problems in practical applications, a fuzzy decision system model constrained by the minimum cost is proposed. In this model, the optimal decision reduction and the minimum decision cost are defined and analyzed as well. As obtaining the optimal decision reduction and its decision cost is NP-complete, three algorithms including the basic algorithm, the greedy algorithm and the Lagrangian relaxation based subgradient optimization algorithm are presented. It is validated experimentally that these algorithms are quite effective, and capable of satisfying needs in different application backgrounds.
  • YANG Zhi-hao; LIN Hong-fei; LI Yan-peng
    Computer Engineering. 2008, 34(7): 203-204,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.072
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    A method is proposed for recognizing the bio-entities (protein, gene, etc.) in biomedical literatures. This method is CRFs-based and selects the appropriate features to recognize the bio-entities. Then the exploitation of the contextual cues is studied to further improve performance. Experimental results show the introduction of contextual cues achieves a performance improvement of nearly 3 percent in F-score, therefore achieving a fairly good overall performance.
  • SHAN Mi-yuan; YUAN Ji-jun
    Computer Engineering. 2008, 34(7): 205-208. https://doi.org/10.3969/j.issn.1000-3428.2008.07.073
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    Complying with product configurability, a logical product model based on non-binary constraint is built. Based on dynamic variable ordering, several configuration-solving methods are proposed. The solving efficiency of different methods is analyzed by the simulation results and the application conditions of the methods for solving configuration problem under different configuration constraint density are given. Based on the logical product model, a valid product configuration can be generated rapidly by applying appropriate solving method in accordance with the character of the configuration problem.
  • YU Juan; NI Zhi-wei; LUO Qin
    Computer Engineering. 2008, 34(7): 209-211. https://doi.org/10.3969/j.issn.1000-3428.2008.07.074
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    According to the normal diagnosis process for the disease, this paper researches the integrated Case-based and Rule-based Reasoning technology, and puts forward a diseases diagnosis system with integrated Case-Based Reasoning(CBR). The theory, the architecture, and the components of the system are introduced, and the critical technology and the function are designed. The designed system consists of the diseases diagnosis, so the automatization of the disease diagnosis process can be improved.
  • ZHANG Li-jun; WU Xiao-juan; SHENG Zan; QI Lei
    Computer Engineering. 2008, 34(7): 212-214,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.075
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    The understanding and recognition of human behavior is a key issue in an intelligence visual surveillance system. But most of the current research is on simple behavior with simple background, so it is not widely applicable. This article presents a method to model complex human behavior hierarchically in complex environment. Set some meaningful landmarks in the screen and model primitive behavior between two landmarks using a HMM, then use Level-Building algorithm with an appropriate threshold model and behavior grammar to recognize complex human behavior. Experimental results show that this method can achieve good results for both simple behavior and complex behavior in complex environment.
  • JIN Li-li; LI Yong-ping; WANG Yong-xu; WANG Lin
    Computer Engineering. 2008, 34(7): 215-217,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.076
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    This paper proposes a fingerprint recognition algorithm based on statistics. Region of interest of a fingerprint image is extracted according to the position and direction of the singular points. Then the two-dimensional principal component analysis approach is applied to the training images represented by ROIs to get the statistical feature space. Fingerprint recognition is performed in the feature space using Euclidean distance classifier. Experimental results obtained on the fingerprint database of FVC2002 prove that the method has the advantages of fast computation speed compared with PCA, and simple implementation compared with traditional minutiae-based approach.
  • WU Cheng-mao
    Computer Engineering. 2008, 34(7): 218-220. https://doi.org/10.3969/j.issn.1000-3428.2008.07.077
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    Considering that the image segmentation method based on mutual information can not obtain ideal segmentation quality on the image with noise or uneven illumination, the new segmentation method based on fuzzy mutual information is proposed. The mutual information is fuzzily modified into the fuzzy mutual information, then it is applied in segmenting image, and the definition method of fuzzy membership function of fuzzy mutual information is given, the method of choosing parameters of fuzzy mutual information in segmenting image is proposed. Experimental results show that the method is more feasible than that of classic mutual information.
  • DONG Shi-du; HUANG Tong-yuan; WANG Hua-qiu; WANG Sen; YANG Xiao-fan
    Computer Engineering. 2008, 34(7): 221-222,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.078
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    This paper proposes a half face recognition scheme to reduce effect of variable light on face recognition. The faces in training set are divided into the left half and the right half, and it trains the left feature extractor and the right feature extractor after illumination compensation respectively. One half of the probe face is chosen by entropy and one’s features are extracted by the corresponding feature extractor after illumination compensation. The face is classified by the features of the chosen half face. Experimental results show that, under variable light, the scheme gains better recognition ratio and speed than the whole face.
  • CEN Yong; ZHONG Ping; LUO Lin-kai
    Computer Engineering. 2008, 34(7): 223-225. https://doi.org/10.3969/j.issn.1000-3428.2008.07.079
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    This paper uses genetic algorithm and support vector machine to set up a hybrid model of financial distress prediction in Chinese listed firms. Numerical simulation shows that the proposed method can reduce the dimension of the feature space, and has higher correct classification rate. As the result, the proposed GA-SVM hybrid model has reliable financial distress prediction ability, and it has a good application prospect in this area.
  • XIAO Guang; SHI Xu-li
    Computer Engineering. 2008, 34(7): 226-228. https://doi.org/10.3969/j.issn.1000-3428.2008.07.080
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    This paper proposes a real-time video object segmentation and retrieval algorithm. The algorithm marks the moving areas, and extracts the object information by using the background detection algorithm. A pixel in object areas and moving areas is set to moving object areas in a frame. Moving object is tracked and indexed by using Hausdorff distance. The algorithm is effective and real-time.
  • LIU Qiong; ZHOU Hui-can; WANG Yao-nan
    Computer Engineering. 2008, 34(7): 229-231. https://doi.org/10.3969/j.issn.1000-3428.2008.07.081
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    This paper proposes a new method for extracting texture features by using multi-layer ideal filters. The method overcomes the bandwidth limitation of traditional Gabor filters, and avoids the complexity of parameters computing in procedure of constructing Gabor filters or Log Gabor filters. On the premise of keeping same performance, the new method predigests the problem. Experiments to extract features and segment multi kinds of textures show that, the new method has almost the same capability in capturing texture features as Gabor and Log Gabor, and improves the efficiency of segmentation.
  • Multimedia Technology and Application
  • LIN Qing-song; XIONG Yan; ZHANG Wei-chao
    Computer Engineering. 2008, 34(7): 232-234,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.082
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    In the environment of streaming Video-on-Demand(VoD) over P2P, search scheme is one of the key factors affecting the Quality of Service(QoS). This article proposes a new self-adaptive probability based search algorithm over circle networks——CircleSearch, which creates circle networks based on the contents of nodes to guarantee the scalability, robustness and distribution of the algorithm. This algorithm spontaneously constructs the “small world” overlay network based on the distances and link reliabilities, which significantly decreases the number of transmission. It uses self-adaptive probability based search algorithm to increase the accuracy of file location. Simulation results show that CircleSearch can provide real-time, stable, controllable and continuous media streaming for system and guarantee the QoS of VoD services with small average path lengths, high success rates and low servers’ loads.
  • JING Tao; WANG Qin; ZHAO Hong-zhi
    Computer Engineering. 2008, 34(7): 235-237. https://doi.org/10.3969/j.issn.1000-3428.2008.07.083
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    For the purpose of high performance and high flexibility of digital speech communication, this paper expatiates one kind of special purpose processor for speech compression based on SELP algorithm, which characterizes reconfigurable, high degree of parallelism, programmable and safety. It discusses the main function, design goal, character design and architecture of the vocoder, and expands on the design of a variable length VLIW instruction set and function units, such as four-stage reconfigurable ALUs and data-path units.
  • XU Yan-ling; LIU Bei
    Computer Engineering. 2008, 34(7): 238-239,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.084
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    This paper proposes coding performance of JPEG-LS image compression algorithm. One-rank rate control scheme and two-rank rate control scheme are proposed to perform dynamic rate control efficiently during the near lossless coding procedure. Experimental results show that these rate-control solutions have low operation requirement and good property of convergence. The fluctuation of bit-rate is effectively reduced. The compressed bit-stream is outputted stably under target bit-rate, and image compression quality is promoted.
  • Engineer Application Technology and Realization
  • GAO Cong-ying; LI Xi
    Computer Engineering. 2008, 34(7): 240-242,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.085
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The DC power distribution box, as the key part of power distribution system, demands high reliability. This paper presents the fault-tolerant design and the implementation of the DC power distribution box based on CAN/LIN bus. It also analyzes the reliability of failure-repair stochastic processes. By using the Markovian process theory and the tool of the Laplace transform, some reliability indexes of the system are obtained, such as the availability, the reliability and the mean time between failures of components and the whole system. On the basis of the mathematical analysis, the model is simulated in Matlab/Simulink environment. The simulation results indicate that the power distribution system has good dynamic performance.
  • DING Guo-liang; YUAN Liang; ZHAO Qiang; ZHU Jie
    Computer Engineering. 2008, 34(7): 243-244,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.086
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    The efficient chromosome presentation scheme is an important factor in the implementation of Evolvable Hardware(EHW). The Virtual Reconfigurable Circuits(VRC) are employed to realize an internal evolvable hardware experiment explained in this paper. VRC is an array of Configurable Functional Blocks(CFB). By using of the multiplexers, the routings of the circuits in CFB can be created effectively. Function choosing of CFB and switching statuses of multiplexers are encoded directly by chromosomes. In this way, the length of chromosome is decreased. Further more, a concrete example is given in order to prove the validity of the method.
  • SONG Wei; FANG Sui-ming; YAO Dan; ZHANG Li-chao; QIAN Cheng
    Computer Engineering. 2008, 34(7): 245-247. https://doi.org/10.3969/j.issn.1000-3428.2008.07.087
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In multi-FPGA designs, the delay of clock transfer causes a huge clock skew between FPGAs and therefore undermines the system performance. To decrease this skew, a circuit based on Delayed Locked Loop(DLL) circuits is proposed. This circuit links the clock transfer path into the feedback loop of DLLs. Thanks to the delayed locked feature, the delay of clock transfer is compensated. Therefore, this circuit reduces the skew between FPGAs and solves the synchronization in multi-FPGA designs.
  • TANG Qi; SU Guang-da
    Computer Engineering. 2008, 34(7): 248-250. https://doi.org/10.3969/j.issn.1000-3428.2008.07.088
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    This paper presents a hardware implementation of face detection system that can detect any number of faces with any size at any position in a 256×256 image, at a speed of 35 fps when the FPGA works at 70 MHz. The detection system can achieve a detection rate of 85% with a false alarm rate of 1.5×10-6. To achieve high speed face detection, three contributions are made in the hardware architecture: real-time hardware implementation of the calculations of integral image and integral squared image, deep pipeline architecture of weak classifier implementation, and parallel multi-memory organization.
  • DONG Pei-chen; SUN Zhen-guo; CHEN Qiang; ZHANG Wen-zeng
    Computer Engineering. 2008, 34(7): 251-253. https://doi.org/10.3969/j.issn.1000-3428.2008.07.089
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    The paper designs a module of data storage with U-Disk based on index file. It meets the fast storing requirement of a great deal of original data gained in the on-line profile measurement system of spiral weld steel pipe with large diameter. The module consists of DSP control system and extended USB host chip named CH375. It realizes the function of data storage in the U-Disk, using the program that embedded in DSP. A format of data storage based on index file is applied to improve the speed of file storage, and it leaves out the searching work of FAT area and root area on the U-Disk. Experiments show that the module is stable and has excellent transplantation. The module can be used in many other systems that need the function of fast data storage.
  • ZHANG Chao; MA Cun-bao; SONG Dong; XU Jia-dong
    Computer Engineering. 2008, 34(7): 254-256. https://doi.org/10.3969/j.issn.1000-3428.2008.07.090
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    Because most avionic equipments have abnormal states and its failure behaviors are always characterized in uncertainty, it is very difficult to analyze its reliability by Fault Tree Analysis(FTA) model which is based on probability theory. To solve this problem, the failure behaviors of bottom events are represented by triangle Vague sets, and the AND/OR fuzzy operators are built based on arithmetic operations of triangle Vague sets, and sequentially the Vague Fault Tree Analysis(VFTA) model is proposed. Three FTA models are adopted respectively to analyze the reliability of a DC system, and the comparisons show that the proposed VFTA model is more flexible and more effective than the other fuzzy FTA models.
  • WU Yu; YU Long-jiang; PIAO Ying
    Computer Engineering. 2008, 34(7): 257-259. https://doi.org/10.3969/j.issn.1000-3428.2008.07.091
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    In order to fulfill the semi-physical test of a digital engine controller, this paper develops aero-thermodynamic models of the engine’s components using VC++ language according to the engine’s aerodynamic arrangement, the geometry and the component’s test characteristics. Thorough consideration is given to the independency of each component and the interaction of aero-thermodynamic parameters of flow-path components in process of constructing classes, to the extent that the component model can represent the real status of the engine working in transient process calculation as well as can be easily connected. Friendly user interface is developed. The simulation results show that the platform has good efficiency and precision.
  • MA Yu-chun; LIU Jie-min; SUN Chang-sheng
    Computer Engineering. 2008, 34(7): 260-262. https://doi.org/10.3969/j.issn.1000-3428.2008.07.092
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    Computer monitor systems are widely used in many fields nowadays. Imitated digital input and output modules, analog input module concerning computer monitor system are designed, including the protocols to operate these ones. RS-232/RJ-45 and RS-232/RS-232 protocol converters are developed to extend the distance of computer monitor system covered. Furthermore, remote serial communication protocols capture and remote system maintenance can be done by these converters. An imitated development platform of computer monitor system is constructed through all the software described above.
  • LI Yu-gang; JI Zhuo-shang; LIN Yan
    Computer Engineering. 2008, 34(7): 263-265. https://doi.org/10.3969/j.issn.1000-3428.2008.07.093
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    This paper proposes a shipbuilding virtual enterprise pattern with the shipyard at center according to the characteristics of shipbuilding industry. The Service Oriented Architecture(SOA) and Web service technologies are introduced. Using the two technologies, the application integration framework is suggested to implement the shipbuilding virtual enterprise. The implementation steps are described. An example is used to illustrate the development and deployment of Web service.
  • Developmental Research
  • ZHANG Ting; CHEN Xiu-wan; ZHU Zhuang-sheng; ZHANG Li-na
    Computer Engineering. 2008, 34(7): 266-268. https://doi.org/10.3969/j.issn.1000-3428.2008.07.094
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    This paper introduces the basic structure of Global Navigation Satellite System(GNSS) software receiver, summarizes its advantages and realizes the whole system regarding GPS software receiver. Except it implements the intermediate frequent signal sampling module for the hardware part, the system is all carried out in software way, including intermediate frequency signal processing module, the signal acquiring and tracking module, ephemeris storage and conversion module, and single-point static positioning module aiming at pseudorange. The errors concerned in the system mainly contain satellite clock error, troposphere error, ionosphere error and the error caused by earth rotation. The result precision can reach 15 meters (95%), even 10 meters with good Geometric Dilution of Precision(GDoP) values. The entire system possesses friendly interface with fine flexibility and extensibility.
  • SUN Jun-man; FANG Hua-jing; SUN Hui-jun; ZHANG Mei-feng;
    Computer Engineering. 2008, 34(7): 269-271. https://doi.org/10.3969/j.issn.1000-3428.2008.07.095
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    This paper presents a general framework for network control systems, where all Lonworks smart nodes are assumed to be connected through a communication network. On the base of analyzing the monitor and control network system, it introduces the event-drivent push technology in alarming system and Java server. With the limit of network band width and network real-time required on control systems, the design with the push technology can reduce network congestion and network delay then the stability of the network control system is much better.
  • FENG Qi; YU Xin-sheng; TANG Li-ping
    Computer Engineering. 2008, 34(7): 272-274,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.096
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    Guide and measure system is a kind of effective tool to emulate the battle environment and evaluate the battle communication system’s function. This article suggests a proper structure of guide and measure system due to the application desire of the emulational environment of command control system. It interprets the design method and the technologies to implement. The control agent disposes in the emulation terminal receives script codes from control software and implement Inter Procedure Communication (IPC) with command control software in each terminal.
  • LIU Yan; LU Yu-chang; CHEN Hai-hong
    Computer Engineering. 2008, 34(7): 275-277. https://doi.org/10.3969/j.issn.1000-3428.2008.07.097
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    According to the cognition psychology theory, this paper expounds the content and the request of teaching model, establishes the model for each factor of teaching design, realizes the related survey. Through excavating the data, and based on the evaluation of student learning and teaching resources, the paper realizes the optimization and attemper of teaching model, sharpens the ability which the teaching system teaches students in accordance with their aptitude.

  • ZHAO Jing; LUO Xing-guo; ZHANG Ru-yun
    Computer Engineering. 2008, 34(7): 278-279,. https://doi.org/10.3969/j.issn.1000-3428.2008.07.098
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    The paper presents a novel collision and overlapping free labeling framework, under which all label positions are indicated by grid number so that labels of points, arcs and polygons are organically linked by grids, and so do labeled objects and unlabeled objects. The algorithm is of good simplicity, efficiency and effects to meet the demand of high quality map label placement, and is successfully applied in commercial GIS.

  • CAO Jian-dong; ZHENG Si-fa; LI Bing; XIA Heng; LIAN Xiao-min
    Computer Engineering. 2008, 34(7): 280-282. https://doi.org/10.3969/j.issn.1000-3428.2008.07.099
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    In order to solve the typical VRPB problem of urban cargo distribution and collection, static vehicle scheduling solution is worked out based on hybrid tabu search algorithm, with the distance matrix calculated using Dijstra and A* algorithm. Dynamic vehicle scheduling system based on GPS/GIS/GPRS technology is developed afterwards. The system inspects the consignment requirements of new customer, and follows up the vehicle location real-time, which is used as input to optimize the vehicle routing dynamic. The routing result is as well quickly transmitted to the vehicle by GPRS.
  • HAN Yi
    Computer Engineering. 2008, 34(7): 283-封三. https://doi.org/10.3969/j.issn.1000-3428.2008.07.100
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    Hierarchical fuzzy optimization is proposed on progress adjustment of hierarchical network plan. The theory of dual-pole fuzzy unit system optimization is utilized in establishing the hierarchical plan adjustment model. Based on the formula of relative membership degree to optimum for mixed indexes, indexes eigenvalue is used to confirm relative membership degree of input indexes. Fuzzy decision set of binary comparison and mood arithmetic operators are adopted to calculate weight of basic unit system. Simulation of the auto assembly project is analyzed, and result demonstrates the effectiveness of the model.