05 October 2008, Volume 34 Issue 19
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Computer Engineering. 2008, 34(19): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2008.19.001In this paper, a posterior-probability-based feature selection algorithm is proposed for imbalanced datasets. In the proposed algorithm, an imbalanced factor is introduced and computed by Parzen-window estimation. The middle point of Tomek links is chosen as the initial point. Accordingly, this algorithm is iterated to find out the boundary points which have the equality of posterior probability. Through the project computation on the normal vectors of these points, the weight of each feature can be obtained, which actually indicates the importance degree of each feature. The experimental results on three real-word datasets demonstrate that this proposed algorithm can not only reduce the computational cost but also overcome the shortcoming that the majority class may be detected well but the minority class may be ignored in the conventional feature selection algorithm.
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Computer Engineering. 2008, 34(19): 4-5,8. https://doi.org/10.3969/j.issn.1000-3428.2008.19.002The computing capability has been demanded increasingly in the industry of water resources in China. In this paper, P2P technology is introduced to collect idle CPU resources to provide high computing capability at a low cost. WAN and LAN-based two-layer XtremWeb network is created on XtremWeb computing platform according to the current situation of water information network. Its relevant model is constructed and analyzed with the theory of M/M/N queue to acquire parameters. And the experiments are taken with XtremWeb network on an example of flooded areas. The results show that the actual time of computing declines rapidly and the system’s volume is close to linear growth while the number of worker increases.
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Computer Engineering. 2008, 34(19): 6-8. https://doi.org/10.3969/j.issn.1000-3428.2008.19.003Online organization issue of the Intelligent Network Disk(IND) is one of key issues of IND storage system. This paper introduces the logical architecture of IND storage system, puts forward the data structure to describe IND and the self-organized algorithm of IND with its Turing, and proves that the algorithm is able to resolve the organization issue of IND by experiments which are finished on high speed local-area network.
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Computer Engineering. 2008, 34(19): 9-11. https://doi.org/10.3969/j.issn.1000-3428.2008.19.004Globalization causes the backup window shrunk sharply. How to backup data efficiently and effectively is one of the most urgent questions today. To solve the above problem, Blue Whale Backup System(BWBS) is designed and implemented. BWBS may backup different file systems and databases by the block-level backup method. And, because the block-level backup may provide backup with less granularity, so with the comparison of the file-level backup, the block-level backup has better improvement at two aspects of backup performance and space use. BWBS uses the policy-driven method to backup automatically in order to implement management automatization.
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Computer Engineering. 2008, 34(19): 12-14,4. https://doi.org/10.3969/j.issn.1000-3428.2008.19.005Integrating the advantages of the table driven routing and the demand routing, this paper proposes a new wireless sensor network routing algorithm. Based on spanning tree theories, the algorithm extends the original single sink node to a set of connective nodes without loop, called the virtual sink, which overlays the whole networks. Monitoring data can be fast transmitted from the sensor nodes to the virtual sink in short-range with the demand routing. And then all of these data are effectively gathered to the real sink node by the table driven routing. The paper studies the optimal method to select the virtual sink, and proposes the “two-hop distance neighbor” algorithm to implement the routing. Using the simulation, each node must reach the virtual sink in two hops. The algorithm is feasible and preferable by computer simulation.
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Computer Engineering. 2008, 34(19): 15-17. https://doi.org/10.3969/j.issn.1000-3428.2008.19.006An actual surface object consisteds of many surface patches. If surface object is directly recognized with range image, it is more difficult to represent the surface object. This paper proposes a method for automatic region segmentation algorithm of range image. The first original segmentation is made by differential invariant, and the range image is divided into many regions with region increase method. The algorithm is simple, and it is easy to understand and program. An example with range image of Mickey Mouse’s head proves the validity of the method.
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Computer Engineering. 2008, 34(19): 18-19,2. https://doi.org/10.3969/j.issn.1000-3428.2008.19.007The WiMAX base stations MAC layer is becoming the system design bottleneck issue due to its protocol complexity, incompleteness and the system large data throughput. This paper contains two key technologies of WiMAX base station and the network processor, proposes a multi-core network processors based WiMAX base stations MAC layer design, gives software and hardware architecture, analyzes the MAC layer data flow and control flow, and provides a feasible solution for the WiMAX base station MAC layer design.
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Computer Engineering. 2008, 34(19): 20-22. https://doi.org/10.3969/j.issn.1000-3428.2008.19.008Randomness test plays an important role in applied cryptography. Binary derivation is one of the randomness test algorithms. The time consuming of algorithm implementing according to the original definition increases linearly with the parameter of binary derivation test. This paper analyses the test procedure based on its theory and educes the relation between the derivation bit and the original bits. It modifies the implementation of the algorithm utilizing the relation and acquires good effect.
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Computer Engineering. 2008, 34(19): 23-25,2. https://doi.org/10.3969/j.issn.1000-3428.2008.19.009Parallelism is an effective method in improving the efficiency of model checking. C program model checking based on LTS is studied and a methodology for parallel software model checking is presented. It utilizes modularity of MAGIC, a software model checker, to decompose C program into components, distributes them over computational nodes and parallel call MAGIC to complete the verification. Close to linear speedup and good scalability can be achieved due to little synchronization and inter-nodes communication. The reduction of time expense is beneficial to formal verification of large-scale software.
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Computer Engineering. 2008, 34(19): 26-29. https://doi.org/10.3969/j.issn.1000-3428.2008.19.010Improvement for search efficiency of Grid Information System(GIS) plays a key role in improving the performance of grid system. In the GIS based on Resource Category Tree(RCT), which uses AVL tree to manager computing resource, when the height of RCT becomes high enough, the search efficiency will be poor. In order to improve the search efficiency, this paper presents an optimization solution based on heuristic search algorithm and applies it in the original system successfully. Detail steps of experiment and result analysis are given. It turns out that this solution does improve the search efficiency of the information system.
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Computer Engineering. 2008, 34(19): 30-31,3. https://doi.org/10.3969/j.issn.1000-3428.2008.19.011Most retrieval systems ignore the anchor text, which is highly relevant to the page content in Web information retrieving. This paper proposes a method to improve the retrieval accuracy. It makes two indices, one for page content and the other for anchor text. A parallel retrieval strategy is utilized for the two indices. Experimental results show that this method is efficient for the special structure document collection.
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Computer Engineering. 2008, 34(19): 32-34. https://doi.org/10.3969/j.issn.1000-3428.2008.19.012This paper presents an electronic auction protocol based on ring signature theory. This protocol is designed for companies’ exclusive auction. The bidders are allowed to submit their bid messages anywhere at any time during the bid period. After this period, they commit their bids. The protocol can protect their privacy, and verify the validity of the bidders. That is, every bidder can prove that he belongs to the group, while does not leak any information of his exact identity, which can protect the bidders’ privacy better.
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Computer Engineering. 2008, 34(19): 35-37,8. https://doi.org/10.3969/j.issn.1000-3428.2008.19.013Aiming at the separation of engineering information and management information during collaborative product development in aviation enterprise, a model of Project Management(PM) system integrated with Product Data Management(PDM) system based on Web services is put out. In this model, the technology of WBS break-down, reflection and correlating based on the BOM is proposed. The bidirectional-refreshing of engineering information and management information is realized by utilizing XML technology. Based on the electronic data bank of PDM system, the project document correlated to the BOM-node is managed by PDM document management platform and shared uniformly and safely in PDM and PM system. The system achievement in an aviation research institute is introduced.
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Computer Engineering. 2008, 34(19): 38-40. https://doi.org/10.3969/j.issn.1000-3428.2008.19.014Data filtering mechanism is the core of data distribution management, and directly affects the rate of data distribution management. This paper proposes a dynamic data filtering mechanism based on best-grid, and analyses the relationship between size of grid cell, quantity of grid in update area and unnecessary information. Experimental results show that the mechanism can improve the rate of data filter, reduce consume of the system and simulation time. It achieves the request of validity, real-time and practicability.
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Computer Engineering. 2008, 34(19): 41-43. https://doi.org/10.3969/j.issn.1000-3428.2008.19.015Acquisition of decision table rule usually needs two steps which are attribute reduction and attribute value reduction. This paper analyses attribute value reduction, and presents a method to acquire briefest rules directly by constructing decision matrix in consistent decision table. This method transforms original considering equivalent relation between condition attribute and decision attribute into considering algebra relation of elements in sameness line in decision matrix. The effectiveness of the algorithm is validated in an example.
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Computer Engineering. 2008, 34(19): 44-46. https://doi.org/10.3969/j.issn.1000-3428.2008.19.016Outlier mining, aim of which is to discover the abnormal data objects in the data set, is an important research aspect in the data mining. The traditional outlier mining algorithms are based on the characteristics of item set, and unsuitable for the application in the multi-objective decision and synthetical evaluation. This paper presents an outlier mining algorithm based on the grey relation analysis. This algorithm is able to mine outliers by the number of the synthetical evaluation and avoid choosing the user-specified threshold. Experimental results show that this algorithm can detect all outliers efficiently in data set, and the mined outliers are coincident and objective.
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Computer Engineering. 2008, 34(19): 47-48,5. https://doi.org/10.3969/j.issn.1000-3428.2008.19.017It becomes more slowly to collect the data by single Web Spider, and higher cost for developing distributed Web Spider by MPI technology or Java technology. This paper designs and realizes a distributed parallel Web Spider with the Active Object, Network parallel computing technology and automatic deployment mechanism provided by ProActive middleware. The experimental results show that the data collection rate of the P-Spider is 2.2 times faster than the data collection rate of the multi-thread Web Spider.
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Computer Engineering. 2008, 34(19): 49-52. https://doi.org/10.3969/j.issn.1000-3428.2008.19.018To improve the dependability of workflow engine in distributed workflow platform made up of workflow definition tool, Web middleware and workflow engine, this paper presents a new method of designing dependable component based on software fault tolerance, hardware and network platform reliability, and message transmission mode according to the system operation analysis. Practical application results show that this method is effective.
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Computer Engineering. 2008, 34(19): 53-55. https://doi.org/10.3969/j.issn.1000-3428.2008.19.019Establishing the index system of performance evaluation is a basic project of the performance evaluation in public administration. Before performance evaluation, it needs to establish an index system of performance evaluation which can adapt to the historical period and exterior environment of the governmental public administration. With the subject of index adaptability, this paper applies XML and MVC design pattern to the performance evaluation software in public administration, presents the design methods from the data describing to the data operating module, and illustrates some key issues in software design process. It finds the method to solve the social science problems from the view of engineering technic.
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Computer Engineering. 2008, 34(19): 56-57,6. https://doi.org/10.3969/j.issn.1000-3428.2008.19.020The account quantum of ontology mapping based on similarity computation is vast, because the amount of concepts and attribute waiting for computing is large. This paper adopts a filtering tactic which uses candidate mapping tactic and information gain tactic to reduce the amount of concepts and attribute waiting for computing. This filtering tactic makes full use of the characteristic of ontology and the idea of data digging, and gets rid of those worthless concepts and attribute to reduce the account quantum of similarity computation. Experimental results indicate that the effect of those concepts and attribute is little.
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Computer Engineering. 2008, 34(19): 58-60. https://doi.org/10.3969/j.issn.1000-3428.2008.19.021Some index technologies based on graph structure improve the query speed of XML data by reducing the searching scope, but there are problems caused by irrelevant nodes comparting. This paper improves the M*(k)-index construction algorithm, and proposes a single index structure, called M**(k)-index to take place of original sequence structure. It avoids storage of nodes and edges in components from sequence, and links between components. M**(k)-index has better storage performance and higher query efficiency. Experimental results show that the improved structure has good performance.
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Computer Engineering. 2008, 34(19): 61-63,6. https://doi.org/10.3969/j.issn.1000-3428.2008.19.022Data exchange becomes more and more frequent between different departments. But these department’s databases are varied. They have different data formats, so there exist conflicts both in semantics and content. In addition, the data need to be exchanged are not fixed, possibly changes along with the service change. This paper proposes a data exchange platform, which takes the end-to-end exchange model as the foundation, and improves it to support the concurrent data exchange ability. It also can satisfy the unfixed format data exchange.
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Computer Engineering. 2008, 34(19): 64-66. https://doi.org/10.3969/j.issn.1000-3428.2008.19.023Fuzzy clustering, two categories of medical Web pages represented by global LSI or local LSI generate two fuzzy sets with a large inclusion degree. A new latent semantic difference model is proposed. The text in medical Webpage is extracted and represented by global LSI, local LSI and difference LSI respectively. FCM algorithm is employed to cluster the feature vectors and inclusion degree between two result fuzzy sets is calculated. Experiments on five given categories of medical Webpages show that, on the average, difference LSI reduces the inclusion degree by a factor of 85% and 80% respectively when compared with global LSI and local LSI.
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Computer Engineering. 2008, 34(19): 67-69. https://doi.org/10.3969/j.issn.1000-3428.2008.19.024The data format XML is easy to create and parse, but significantly large and hard to implement search on it. This paper introduces XBW transformation to compress XML data to three arrays, transfers the search process from tree structure to the three arrays, and implements the search process by Rank&Select method. This paper also proposes navigation, subpath search and content search algorithms based on XBW transformation. Experimental results show that the performance of XBWZIP approach surpasses some queriable XML compressors and some general-purpose compressor in terms of compression ratio and compression time.
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Computer Engineering. 2008, 34(19): 70-72. https://doi.org/10.3969/j.issn.1000-3428.2008.19.025Taking the project research of CWPS as background, this paper proposes a design of XML parser based on blackboard structure pattern. Shortcomings of traditional compilers are analyzed. An architecture of XML parser is proposed to expound the architecture design theory. The key technologies of implementation are discussed, including the algorithm of building DOM tree, the object model of schema tree, the algorithm of availability validation and parsing engine. The architecture is feasible through the validation test and the results are satisfied.
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Computer Engineering. 2008, 34(19): 73-75,7. https://doi.org/10.3969/j.issn.1000-3428.2008.19.026This paper mainly researches the portability of mobile software among different protocol stacks, and it implements a valid adapter framework which is based on attention command protocol. At the condition of hardly changing the structure of mobile software, it implements the communication between the upper communication layer and other chipsets, other GSM modems or other communication protocol by AT commands, so the current mobile software development can be independent of the specific protocol stack. Meanwhile, the related functions of short message are implemented and verified on the framework.
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Computer Engineering. 2008, 34(19): 76-79. https://doi.org/10.3969/j.issn.1000-3428.2008.19.027There are many components and resources in symposium system of meta-synthetic, which need to be published, found, invoked and integrated dynamically. A meta-synthetic engineering framework combined with experts, machines and knowledge is discussed. A new SOA pattern is proposed, which extends QoS and security. Data integration method is analyzed. A symposium system of meta-synthetic engineering based on the new SOA pattern is developed.
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Computer Engineering. 2008, 34(19): 80-82. https://doi.org/10.3969/j.issn.1000-3428.2008.19.028By summarizing the rules of the code of man-machine interface, this paper proposes an idea using Excel worksheets to describe man-machine interface. It designs the “three description segments rule” used to describe parameters in the man-machine interface and automatic code generating software design of man-machine interface for switch. By this rule, the difficult problem of description of man-machine interface and parameters is solved successfully. Put the “phone transaction statistics” man-machine interface described in this article as an example, the running result of the code automatically generated by the software is briefly explained. The practical running result of the software indicates that it can greatly save development time and improve developing efficiency.
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Computer Engineering. 2008, 34(19): 83-85. https://doi.org/10.3969/j.issn.1000-3428.2008.19.029The process will improve the response speed of Web application by using Ajax technology when Web pages communicate with Web server, however, when the Web pages refreshed by Web server widget, the view state process model of the Web page records Web server widget’s state value does not record the Ajax widget’s value and leads to the loss of the Ajax widget’s value. This paper presents a new state value storage mechanism, which makes Ajax widget’s state value be stored in the Web server session object or the user data object of the client side, so that the Ajax widget of the client side can still hold the same value after the Web page refreshed, which ensures the Ajax widgets state continuance.
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Computer Engineering. 2008, 34(19): 86-88. https://doi.org/10.3969/j.issn.1000-3428.2008.19.030Due to the overload condition for the network information filtering system, this paper proposes the strategy that improves filtering speed paying a little loss of precision and recall, uses approximate methods such as text sampling and pattern generalizing. It can retain most of the filtering capability in overload condition. The experimental results show that the filtering capacity can be improved about three times while losing only less than 15% of precision or recall and has a remarkable performance promotion.
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Computer Engineering. 2008, 34(19): 89-91. https://doi.org/10.3969/j.issn.1000-3428.2008.19.031To promise QoS of the many coinstantaneous requests in the Web Service, it needs some control algorithms to control the requests. This paper analyzes structure of delay parameter of QoS and brings forward a service admission control algorithm satisfied with requirement for service delay parameter. The algorithm judges whether server can accept the new request in the condition that can promise the delay parameter of QoS for the running services in the server, otherwise server refuses the request, and then assigns the request waiting in the line or discards this request directly and let the client requests again after the time-out be elapsed.
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Computer Engineering. 2008, 34(19): 92-93,1. https://doi.org/10.3969/j.issn.1000-3428.2008.19.032The automatic search and community discovery in large and complex network has important practical applications. This paper applies the hypergraph based model and cluster algorithm in community structure discovery, introduces the concept of Edge Clustering Coefficient(ECC) to community structure discovery of simple graph and proposes an algorithm of community discovery based on ECC. Enron e-mail data sets are test data sets, through comparative analysis of algorithm, to prove that this algorithm can significantly improve the time complexity.
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Computer Engineering. 2008, 34(19): 94-97. https://doi.org/10.3969/j.issn.1000-3428.2008.19.033Service migration should include three types of state——initial state, active state and complete state. Based on these, this paper proposes the architecture of service migration and analyzes the realization of service migration. When facing security threat, service migration determines whether to migrate, either actively or passively. It is transparent to the users so that they will not feel the change of service. It just migrates the service states with the purpose of shorting migration time by reducing transmitted data. The migration of FTP service is realized.
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Computer Engineering. 2008, 34(19): 98-100. https://doi.org/10.3969/j.issn.1000-3428.2008.19.034This paper proposes a scheme of Ad hoc network architecture which combines Dynamic Source Routing (DSR) protocol and Adaptive On-demand Weighted(AOW) clustering algorithm. Using AOW algorithm, the cluster radius is strictly controlled within a hop and cluster-members do not need routing function, greatly reducing the redundancy of routing information. Each cluster-header implements the DSR Protocol, working as a router. The communication between nodes coming from different clusters relies on cluster-headers. Simulation result shows that the scheme has good performance. It has been implemented in Windows XP operating system.
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Computer Engineering. 2008, 34(19): 101-103. https://doi.org/10.3969/j.issn.1000-3428.2008.19.035This paper presents a Clustered-based Relative Localization Algorithm(CRL)for Wireless Sensor Networks(WSN). CRL has three phrases: the network is divided into clusters; each cluster builds Local Coordinate System(LCS) and each node computes its own position within corresponding LCS; every LCS incorporates into a global coordinate system. Experimental results show that compared to SDGPSN, the algorithm has less communication and time overhead and it is more suitable for energy-constrained and large-scale WSN.
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Computer Engineering. 2008, 34(19): 104-106. https://doi.org/10.3969/j.issn.1000-3428.2008.19.036Wireless sensor networks need deploy suitable numbers of nodes to assure the connectivity of networks in stochastic-deployed environments. The connectivity is the guarantee of service and function of wireless sensor networks. The paper puts forward a stochastic-deployed mathematic model based on different conditions. Simulation tests demonstrate that the model is valid and it provides the basic theory for stochastic-deployed application in wireless sensor networks.
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Computer Engineering. 2008, 34(19): 107-108,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.037Matching location based on signal strength is the primary method of Wireless LAN(WLAN) location, which includes offline training phase and online location determination phase. This paper improves the traditional algorithm of offline location determination phase. By selecting some greater probability points for location, it calculates the position with coefficients that comes from probability. Experimental results demonstrate that the algorithm can improve the accuracy of location obviously.
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Computer Engineering. 2008, 34(19): 109-111. https://doi.org/10.3969/j.issn.1000-3428.2008.19.038Data is a kind of resources in grid environment, it has many differences with other resources. Its flow, management and uniform view play an important role in grid system. This paper analyzes the characteristic of data, designs and implements a grid datatransfer subsystem based on FTP protocol, which abets multithreading download, break point transfer, exception identify and connection maintain. Also the subsystem implements two transfer models which are “not landed” transfer model and third control transfer model. It not only offers grid the ability of deploying data, gives data help of running task with super computers and clusters, but also forms uniform data view of all data, making it convenient to take deeper work.
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Computer Engineering. 2008, 34(19): 112-114,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.039More recent studies have proposed that fractal is a ubiquitous property of real-traffic, and the multi-fractal of traffic has great impact on network performances. So it is important to build the forecasting model based on multi-fractal for service quality of network, which is a good traffic model capable of capturing both Long-Range Dependence(LRD) and short-range behavior of a network traffic stream. As the AR and ARMA models have a good prediction to the short-range dependence data except for the LRD, it proposes a new prediction model which has the great accuracy for the LRD, it is based on Wavelet transformation which can release the correlation of data. So the new model overcomes the defect of the FARIMA model, and maintains the simplicity of the algorithm.
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Computer Engineering. 2008, 34(19): 115-117,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.040This paper presents a QoS architecture for tactical Ad Hoc networks. The QoS architecture can differentiate traffics with different priority and different QoS demand. When there are not enough resources in the network, traffics with high priority can access network through “preemption”. This architecture also guarantees traffics with low priority to use network resources fairly. Simulation results show that this QoS architecture can satisfy traffics with different priority’s Qos demand.
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Computer Engineering. 2008, 34(19): 118-120. https://doi.org/10.3969/j.issn.1000-3428.2008.19.041As a result of transmitting larges numbers of messages in bully algorithm of distributed algorithm, the performance of the communication is degraded. This paper analyzes the defection of Bully algorithm and proposes an optimal algorithm based on it. Comparing the two algorithms, the new algorithm can improve communications performance, avoid network delay and network congestion.
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Computer Engineering. 2008, 34(19): 121-122,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.042This paper introduces Ad Hoc networks and the routing protocols, presents the analysis and simulations of the link repair of the Ad Hoc On-demand Distance Vector(AODV) protocol and provides a new scheme to improve the performance of link repair. By overhearing the routing information, the new scheme uses broadcasting to repair broken routes. Simulations results indicate that the improvement in less delay and routing overhead while compared with the traditional method to some extent.
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Computer Engineering. 2008, 34(19): 123-126. https://doi.org/10.3969/j.issn.1000-3428.2008.19.043With the P2P application transferring from read-only static files sharing to read-write dynamical files interacting, maintaining consistency between frequently-updated files is very important. This paper presents a replication index based consistency maintenance strategy. When a node downloads files from the seed node or other replication nodes, the node sends its address to the seed node, and seed node saves the address in its replication index table. When a node’s vision of the replication is newer, the node sends update message to seed node. According to the vision of the replication, the seed node decides whether to do the consistency maintenance. Experimental results show that the replication index based strategy can largely reduce the number of the duplicated messages. It can obviously improve the coverage.
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Computer Engineering. 2008, 34(19): 127-129. https://doi.org/10.3969/j.issn.1000-3428.2008.19.044This paper presents an adaptive search mechanism for mobile P2P networks. It utilizes the feedback from previous searches to compute dynamically the popularity of the objects of the nodes, and proactively distributs file metadata according to the popularity. To decrease the number of queries, the mechanism utilizes the position information of the popular nodes or the nodes that can return the most query results to guide the queries. Experimental result shows that the strategy can remarkably improve the search efficiency with the small response time, high success rates and the eminent adaptability to the change of hot resources.
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Computer Engineering. 2008, 34(19): 130-132. https://doi.org/10.3969/j.issn.1000-3428.2008.19.045A kind of wireless Mesh network is designed and applied for the special environments of underground mine. This network mainly affords wireless VoIP service and can provide video services as well. It implements call access and roaming of IP phone in network layer. By testing in practical experiments, it selects the appropriate parameters, such as setting place of nodes, the receiver sensitivity threshold of all access points. An idiographic wireless IP network in underground mine is build and configured based on these parameters.
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Computer Engineering. 2008, 34(19): 133-136,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.046Vulnerability is the main origin of network security incident. A large number of vulnerabilities and their dangers make rating vulnerabilities become particularly important. This paper analyzes well-known security agencies and manufacturers’ characteristics of rating vulnerability, introduces the Common Vulnerability Scoring System(CVSS) and its shortcomings, proposes a more complete quantitative rating system CVRS on the basis of CVSS against CVSS’s shortcomings, and illustrates the validity and superiority of CVRS through some instances.
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Computer Engineering. 2008, 34(19): 137-140. https://doi.org/10.3969/j.issn.1000-3428.2008.19.047Aiming at the current J2EE application server’s limitation for intrusion tolerance, a method to design a J2EE application server with intrusion tolerance function is proposed. By the way of establishing a secure group communication system in the group communication layer of the J2EE application server, an intrusion tolerance interceptor and framework in the server are designed. The intrusion tolerance services can be added transparently and they are integratable, pluggable, expandable. The method applies intrusion tolerance, group communication and interceptor technology to provide a simple and available method to solve the intrusion tolerance problem of J2EE application server realm in the distributed environment.
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Computer Engineering. 2008, 34(19): 141-143. https://doi.org/10.3969/j.issn.1000-3428.2008.19.048A new packet marking scheme is proposed, in which a path identification that represents the route an IP packet has traversed is embedded in each IP packet. And a counter is set for each identification. It represents the number of different IP addresses that have the same identification. The onset of a spoofed DDoS attack can be detected by comparing the sum of the counters with a marginal value that has been set. Spoofed packet can be filtered so as to sustain the quality of protected Internet services. Experimental results show that the proposed scheme is efficient on identifying the spoofed DDoS attack packets.
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Computer Engineering. 2008, 34(19): 144-146. https://doi.org/10.3969/j.issn.1000-3428.2008.19.049Aiming at the security needs of enterprise application which is with the Service-Oriented Architecture(SOA), this paper analyzes the features of WS-BPEL business process, and then proposes an execution-oriented access control model, which can grant and withdraw permissions dynamically. Meanwhile, role and constraint mechanism are introduced. On the foundation of the former work, business activities are mapped to access control elements, so that the model can accomplish the work of access control for the process under the condition of separation between process definition and permission management.
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Computer Engineering. 2008, 34(19): 147-150. https://doi.org/10.3969/j.issn.1000-3428.2008.19.050Anciently, the implementation of security gateway only emphasizes on one side function and the authentication way is not flexible. This paper researches and analyzes deeply on latest IKEv2 protocol of dynamic key negotiation mechanism and combines the advantages of EAP, then gives a solution that introduces the EAP/SIM authentication framework into IKE authentication system and designs an enhanced extensible IKEv2 system based on EAP/SIM. IKEv2-EAP system takes RADIUS as the authentication server implementing AAA functions and employs up-to-date IKEv2-EAP/SIM interaction setting up the secure IPSec channels. This makes the function of VPN gateway more flexible, stronger and diversity.
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Computer Engineering. 2008, 34(19): 151-153,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.051Fuzzing is an automatic vulnerability discovery technique. Based on the analysis of OBEX protocol, this paper designs and implements a bluetooth OBEX protocol Fuzzing tool, OBEX-Fuzzer. Two implementations of OBEX protocol in Nokia N73 and SMH-BT555 bluetooth adaptor have been tested by the tool. In result, several vulnerabilities have been found in them, which indicates that the research route is correct and the OBEX-Fuzzer tool is effective.
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Computer Engineering. 2008, 34(19): 157-159. https://doi.org/10.3969/j.issn.1000-3428.2008.19.053In this paper, the process of reducing systems of equations is improved, and a more efficient algorithm for solving systems is developed. The improved algorithm uses the relation of all the monomials sufficiently for reducing systems of equations, and removes the high-degree monomials. Simultaneously, the systems are expanded and reduced step by step in order to remove the redundant equations, decrease the computing and saving complexity of the XL algorithm. And more, the improved algorithm can be applied to constructing the low-degree Annihilators of Boolean function.
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Computer Engineering. 2008, 34(19): 160-162,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.054It is an effective method to protect software by packing Portable Executable(PE) files. But the technology which is commonly used by most packing software is a statically packing technology, and it exists a shortage that all the PE files packed by the same packing software have partly uniform code, thus increases the possibility of the packed software being decrypted, which can not fully satisfy the requirement to protect PE files. Based on the analysis of the PE file format and loading mechanism, this paper proposes the idea of dynamically packing for PE files, designs and implements a prototype of dynamically packing for PE files. The experimental results show dynamically packing technology can be used to improve the protection capability of PE files.
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Computer Engineering. 2008, 34(19): 163-166. https://doi.org/10.3969/j.issn.1000-3428.2008.19.055The concept of Usage Control(UCON) is introduced as a unified approach. The UCON model includes authorization model, obligation model and condition model. Dynamic description logic is proposed for authorization model, by combining the features of reasoning and capturing factors of authorization. An integrated authorization instance is provided. This logical model provides a fine foundation for application of UCON.
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Computer Engineering. 2008, 34(19): 167-169,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.056This paper designs and implements a Website protection system which is based on network survivability. Based on afterward recovery, real-time monitoring and packet filtering using NDIS intermediate driver are adopted to protect the Website documents. The system protects data in the database with trigger mechanisms offered by DBMS. Moreover, through priority management, it protects data in the database with trigger mechanisms offered by DBMS. Experimental result shows that the Website protection system ensures safe operation and implements the survivability of Website system.
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Computer Engineering. 2008, 34(19): 170-173. https://doi.org/10.3969/j.issn.1000-3428.2008.19.057Radio Frequency Identification(RFID) as a new automated identification technology has become popular in many applications. But the features of the RFID systems and the constraints of RFID devices bring about various privacy problems. To address these issues, the structure and privacy problems of RFID systems are discussed and clarified in this paper, and the features and issues pertinent to several current typical RFID security protocols are analyzed. A new security protocol for RFID based on key matrix is proposed. Encrypting the data transported between tags and readers by key matrix and renewing the tag’s secret value after each authentication, the protocol efficiently prevents multiple attacks. Analysis shows that this protocol is high efficiency, low-cost and good security.
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Computer Engineering. 2008, 34(19): 174-175,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.058The most anonymity communication system only provides sender anonymity presently, such as Crowds which makes use of forward probability to conceal the identity of the sender, but the identity of responder for members in Crowds is public. According to the ideas of Crowds and multicast, a novel Bidirectional Anonymity Communication Protocol(BACP) is proposed in the paper, which forwards messages randomly in members to achieve sender anonymity. When messages are decided to submit, the messages are submitted to responder by multicast so as to realize recipient anonymity.
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Computer Engineering. 2008, 34(19): 176-178. https://doi.org/10.3969/j.issn.1000-3428.2008.19.059This paper analyzes the main menace of session security, and describes the basic principle and method of session hijacking. A secure session module based on HTTP is designed for repelling session hijacking attack. The module adds a hashed MAC to session IDs, and monitors incoming requests and outgoing responses for session ID cookies. It makes it difficult for attacker to reuse the sessions ID cookie and gives Web applications well protected. It achieves the secure session module based on the .net platform, and the module is used on an e-business Web site.
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Computer Engineering. 2008, 34(19): 179-181,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.060Statistical analysis based on complexity histogram discontinuities measure is a powerful steganalytic technique for detecting the presence of secret message embedded in the digital images using Bit-Plane Complexity Segmentation(BPCS). Therefore, to improve steganographic security, this paper proposes an improved BPCS algorithm that can effectively resist statistical analysis. Part of blocks are used that can embed hiding information as complexity adjustable blocks to remove two clearly discontinuities which are caused by customary BPCS algorithm, and make sure the discontinuities measure disappear obviously peak value. Experimental results show that the improved algorithm can effectively resist statistical analysis based on the complexity histogram, and can maintain the big capacity characteristic of the originally algorithm.
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Computer Engineering. 2008, 34(19): 182-184. https://doi.org/10.3969/j.issn.1000-3428.2008.19.061This paper presents a face detection method based on histogram statistical learning. It does wavelet transform to the face samples and non-face samples and uses groups of wavelet coefficients to represent all kinds of attributes of face. The probability distribution of visual attributes of face and non-face is represented by statistics of distribution of histograms for each training sample, and each histogram represents the joint probability distribution of a subset of wavelet coefficients and their position on the face. This method can detect multiple faces in the natural scenes accurately. It gives a good detection performance for profile-view face detection.
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Computer Engineering. 2008, 34(19): 185-186,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.062This paper establishes a detection system for circular parts based on machine vision technique, which uses calibration method and sub-pixel technique to implement the untouched exact measure of circular holes and circular parts. The diameter measure process of circular holes and circular parts includes image capture, image analysis and disposal, and measure results output. The image compensation, image preprocess, image binarization, and circle detect methods are used in the core algorithm of this system. Experimental results prove that it realizes online real-time detection with high accuracy in 0.01 mm and has broad prospects for the application.
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Computer Engineering. 2008, 34(19): 187-188,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.063To maintain a data mining model, it is necessary to repeat related computation for frequent changing data sets, and this will lead to the low efficiency problem. This paper uses Ensemble learning to study generation of weak classifiers on incremental data sets, and presents a new combination algorithm according to dissimilarity of classifiers of incremental data sets. It analyzes the error rate of the combined classifier. Experimental results show the effectiveness of the classification method.
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Computer Engineering. 2008, 34(19): 189-191. https://doi.org/10.3969/j.issn.1000-3428.2008.19.064This paper proposes an improved Genetic Algorithm(GA). The ranking selection intensity adopts an adaptive adjusting mechanism, which can adjust the selection intensity dynamically according to the change of the population state. A new crossover strategy which chooses the outstanding individuals according to competition is used to increase the individual average performance of the population. The simulation with the typical test functions indicates that this algorithm can improve the precision of solutions and convergence speed of simple genetic algorithm, and the proportion of convergence can reach more than 90%.
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Computer Engineering. 2008, 34(19): 192-194. https://doi.org/10.3969/j.issn.1000-3428.2008.19.065The artificial fish swarm algorithm is a swarm intelligence optimization algorithm based on the animal behavior. An improved artificial fish swarm algorithm is presented. This algorithm directly moves artificial fishes to the superior position while searching food so that increasing the algorithm’s searching speed. It dynamically adjusts the vision and step of artificial fish, makes the vision and step maintain maximum during the initial period of running, and then makes them smaller gradually. This algorithm can keep the balance between global and local search ability, and enhance the running efficiency and precision of the algorithm. The simulation results show that the improved artificial fish swarm algorithm’s convergence performance is more than twice of the former algorithm.
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Computer Engineering. 2008, 34(19): 195-196,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.066The traditional Coordination Mechanism(CM) evaluation and selection models are not generic and prone to fall into local optimal decision. It is hard to establish a CM library and design evaluation function when using these traditional coordination mechanisms. The traditional coordination mechanisms cannot meet the needs of modern complicated cooperation systems. Aiming at the CM dynamic selection system, a generic model of CM evaluation is proposed, and a GA of search for global joint optimal CM and its parameter is designed. The generic model and genetic method are simulated. Simulation results show that this model overcomes the traditional models’ drawbacks, and its algorithm can search out the global joint optimal CM.
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Computer Engineering. 2008, 34(19): 197-199. https://doi.org/10.3969/j.issn.1000-3428.2008.19.067This paper implements a simulation system for single camera Simultaneous Localization And Mapping(SLAM), and presents the design process. This system has good work performance, and its SLAM algorithms has high expansibility, which can approach the real single camera SLAM process. It aids to convenience the research of SLAM algorithm, provides a lot of useful functions to record, observe and analyze simulation results, which makes repeating experiments and comparing algorithm effect more easily.
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Computer Engineering. 2008, 34(19): 200-202. https://doi.org/10.3969/j.issn.1000-3428.2008.19.068To overcome the drawbacks of solving middle-scale and big-scale TSP problem such as easy to stagnation, when using ACS-3-opt(Ant Colony System plus 3-opt), an improved algorithm is proposed, whose cores are that after stagnation of ACS-3-opt increase the quantity of ants with local search ability and enhance minimum pheromone threshold to enlarge search space. When algorithm stagnates again, it reinforces the pheromone of the common path of the two best tours generated. The reinforcement for the common path provides a good initial information for later running, guiding the algorithm to the best tour. The results of solving middle-scale and big-scale TSP problem show that the algorithm can skip from local optimum effectively and the solution is better than ACS-3-opt.
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Computer Engineering. 2008, 34(19): 203-205. https://doi.org/10.3969/j.issn.1000-3428.2008.19.069This paper proposes a new method, which uses MFCC combined with complexity. Some experiments are conducted by using OGI-TS telephone speech corpus. Vector quantization method is employed to recognize three languages (English, Mandarin and Japanese), and it analyzes the effects of language identification. It is shown that the method can remarkably improve the recognition accuracy and robustness.
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Computer Engineering. 2008, 34(19): 206-208. https://doi.org/10.3969/j.issn.1000-3428.2008.19.070Support Vector Machine(SVM) presents excellent performance to solve the problems with small sample, nonlinear and the problems of high-dimension pattern recognition, but the process of selecting support vector is quite complicated. Therefore a density clustering algorithm based on search is put forward. Through a sample search strategy the algorithm can cluster the object that its density is over certain threshold to one class, and the application of it to pre-extracting support vector can reduce the number of training samples and improve the training speed of SVM. From the simulation experiments, it can be found that through pre-extracting support vector based on search density clustering algorithm, the number of training sample can reduce 2/3, and the training speed can quicken 12 times for linear separable data and quicken 5 times for nonlinear separable data.
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Computer Engineering. 2008, 34(19): 209-211. https://doi.org/10.3969/j.issn.1000-3428.2008.19.071Precision and speed are two appraisal criterions of face detection system. In order to get accurate precision and fast speed, this paper presents a novel method based on skin model and regional feature. This method extracts face pixels using skin model, then gets the face region through an extension method of mosaic, extracts the lip and eyes utilizing the built models and locates the central points based on the regional feature. Experiments show that the method performs easily and locates points accurately.
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Computer Engineering. 2008, 34(19): 212-214. https://doi.org/10.3969/j.issn.1000-3428.2008.19.072This paper designs and implements a Topic Detection and Tracking(TDT) system to process the huge number of natural language text on Web. It classifies the text into several categories, performs clustering in each category to get the topic. The system can detect the hot topics in real-time and track some topics selected by user. The accuracy of text classification is 92%, and the accuracy of clustering is 88%. Experiment shows the feasibility of the TDT system.
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Computer Engineering. 2008, 34(19): 215-217. https://doi.org/10.3969/j.issn.1000-3428.2008.19.073Image processing technology has been proved to be an efficient method of analyzing fabric structures, colors and identifying fabric weave patterns. In order to improve color pre-processing effectiveness, color pre-processing functions using the HSV color space are designed in this paper. After the main colors in the fabric image are extracted by the color quantization method, the improved color quantization method is adopted to merge similar yarn colors and realizes the aim of reducing the total number of yarn color. Experimental results show that the color detection and representation is effective.
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Computer Engineering. 2008, 34(19): 218-221. https://doi.org/10.3969/j.issn.1000-3428.2008.19.074By analyzing the basic principles of General Fuzzy Min-Max(GFMM) neural network and the accuracy and high performance of fuzzy computation for information intelligent processing, the GFMM neural network is applied to the corporation’s credit rating. With genuine inputs of fuzzy realized, the quantitative inaccuracy of standards of evaluating corporations is alleviated to a large degree. Through credit rating towards companies, it is proved that the algorithm can classify companies availably at a high speed. A new project to credit rating is proposed.
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Computer Engineering. 2008, 34(19): 222-224. https://doi.org/10.3969/j.issn.1000-3428.2008.19.075The article puts forward a new method for multi-object tracking with single camera. All of the new object area can be obtained by using the overall background subtraction in current frame, then making use of kalman filter and partial background subtractions, potential object area is obtained .According to the position and size of the new object area and the potential object area, it judges whether there is merger or cover exit, and uses different match method to carry on object tracking. Experimental result shows the algorithms can solve the problems such as merger or cover effectively with single camera, and have strong ability in multi-object tracking.
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Computer Engineering. 2008, 34(19): 225-227. https://doi.org/10.3969/j.issn.1000-3428.2008.19.076With the perspective of increasing the degree of parallelism of the on-chip peripherals and the core, this paper introduces the pipeline idea, implements a control architecture based on polling and ping-pong buffers, and develops it to an improved dual-stage control architecture. H.264-based video encoder is implemented under the architecture. Practical tests show that this system can meet the requirements of real-time capability and stability in video communications.
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Computer Engineering. 2008, 34(19): 228-229,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.077In order to reduce the complexity of H.264 encoding algorithm, this paper proposes a fast mode decision algorithm for intra prediction. The prediction type of a macroblock is decided according to the differences between the neighboring pixels of a macroblock. Pan’s fast algorithm based on edge direction histogram is improved to predict the macroblock; therefore the best prediction mode is chosen. Experimental results show that the method can save the encoding time up to 71.6% averagely when guarantee the capability of the rate distortion and the bits rate, and it improves the encoding efficiency tremendously.
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Computer Engineering. 2008, 34(19): 230-232,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.078This paper models each of the video frames as an adaptive Gaussian Mixture Model(GMM), and uses this model to extract the background image and to segment the moving regions. The color information is used to detect playfield based on the background image. In order to enhance the accuracy of the detected player regions, texture similarity measure is employed to remove the shadows, and a morphologic method is adopted to fill the gaps inside the player regions, noise is removed based on the playfield information. This paper improves the CamShift algorighm, which is used to track the players automatically.
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Computer Engineering. 2008, 34(19): 233-235. https://doi.org/10.3969/j.issn.1000-3428.2008.19.079The main feature of SP/SI frame of H.264/AVC frames is that identical frames can be reconstructed even when different reference frames are used for prediction. This paper proposes a scheme to implement Video Cassette Recording(VCR) functions of H.264/AVC video by utilizing the SP/SI frame and multi-reference frame. It can eliminate the drifting problem of dual-bitstream technique. Experimental results show that the scheme can reduce the network bandwidth by about 40% under VCR operation compared with traditional one, and PSNR improves over 1 dB.
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Computer Engineering. 2008, 34(19): 236-238,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.080This paper proposes a design scheme of hardware accelerator for CABAC decoder in H.264. It develops an efficient FSM and SRAM system so that the decoder can generate 1 bit every cycle, and it is capable of decoding High Profile(HP) video stream, achieving the requirement of real-time decoding. An ASIC implementation of the design is carried out in a 0.18 µm standard cell library of silicon technology, the estimated frequency is 196 MHz and the area includes 47 444 gates.
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Computer Engineering. 2008, 34(19): 239-241. https://doi.org/10.3969/j.issn.1000-3428.2008.19.081This paper proposes a new method to detect anchorperson shots automatically in news video based on extended face region. In a single news video, the anchor wears the same dress through out the entire program. It takes this fact as the cue, which is independent of the image background as well as the location of the anchor. The anchor extended face regions are extracted as templates on-line and the grid HSV histogram is taken as the template parameter. The well-defined extended face regions are used to match the potential extended face regions from the shots to identify the anchorperson shots. Experimental results show that the new method is efficient, and the detection accuracy is improved compared with the classic methods.
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Computer Engineering. 2008, 34(19): 242-243,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.082Bridge collaborative design is a process of data continuous generation and management. How to improve the efficiency of data storage and management influences design quality and design period. Based on the analysis of bridge design system in data storage, a model for data representation of bridge collaborative design system is presented. Two kinds of data pre-defining storage mode including interactive mode and knowledge-based mode are studied. Pre-defining model of data storage is validated through an engineer project.
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Computer Engineering. 2008, 34(19): 244-247. https://doi.org/10.3969/j.issn.1000-3428.2008.19.083This paper introduces the design and implementation of an AHB bus bridge of crossing clock domains. By adopting the state machine design method and using the merging of prevent-deadlock and break-deadlock to deal with deadlock, the bridge can support read/write burst, pre-fetch operation for reading, deprived bus arbiter etc operations and simplify the implementation. Performance test indicates that it can improve the system bandwidth and timing performance greatly.
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Computer Engineering. 2008, 34(19): 248-250. https://doi.org/10.3969/j.issn.1000-3428.2008.19.084This paper presents architecture of production line oriented Radio Frequency Identification(RFID) system. The communication course of RFID based on Electronic Product Code(EPC) protocol is analyzed, and the simulation of the RFID system and analysis of its communication characteristic are made. It utilizes S-function of Simulink to encode and decode, to achieve baseband function modules. In effect of Rician attenuation and AWGN generated from the environment of automatic production line, 16-QAM(Quadrature Amplitude Modulation) is utilized by the system. The relationship between signal-to-noise and bit-error-ratio is given. Simulation results indicate that the system architecture is feasible, the rate and reliability of data transmission are improved, which offers references to system application in scientific and reasonable design of RFID system.
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Computer Engineering. 2008, 34(19): 251-253,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.085This paper presents the design and implementation of a cycle accurate behavior model for a DSP microprocessor based on transaction level modeling in ESL methodology. This model explores several key issues of a processor design, such as the sub block partition, the pipeline organization and the instruction operations in each cycle. By ESL simulation tools, it can easily understand the detailed operations of the model, which greatly helps and accelerates the process of logical design and functional verification.
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Computer Engineering. 2008, 34(19): 254-255,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.086The transient signal is abrupt and singular after transmission line faults occur. And the signal contains abundant fault information. The transmission line damage is mostly caused by short-circuited fault. The short-circuited fault is analyzed and then the fault current is detected using lifting wavelet. According to the actual power system transmission line, short-circuited fault simulation is set up. The simulation results show that lifting wavelet not only effectively detects the signal singularity of transmission line short-circuited fault but also runs 3 ms(millisecond) faster than db5 wavelet, which provides support for next fault location.
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Computer Engineering. 2008, 34(19): 256-257,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.087This paper introduces one design method of the CAN bus interface and the RS232 bus interface interconversion, emphasizes two kind of bus level transformation relations, realizes the CAN bus and various modules connection design, formulates the design proposal of corresponding software and hardware, and gives the flow chart of software design as well as the partial schematic diagram of hardware design. It provides one method for the CAN bus and the RS232 bus interconnection, has the vital significance to widespread application realization of the CAN bus and the RS232 bus interface equipment interconnection.
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Computer Engineering. 2008, 34(19): 258-260. https://doi.org/10.3969/j.issn.1000-3428.2008.19.088Aiming at the focus problem of government horizon business integration, the Hierarchical Role Network Model(HRNM) is considered as the management and control model. The architecture and key technologies of the Government Horizon Business Integration Management System(GHBIMS) based on HRNM and multi-Agent are presented. An example of one-stop administrative permit system is given based on the above technologies. HRNM and GHBIMS stress the importance of the role, may adequately satisfy the dynamic characteristics of government horizon business integration, and have good application prospects.
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Computer Engineering. 2008, 34(19): 261-263. https://doi.org/10.3969/j.issn.1000-3428.2008.19.089This paper explores how to address the real-time control problem of real-time management system of flight simulation based on Linux. For this purpose, RTAI, a community project for real-time extension of Linux, and its hard real-time solution in user mode, LXRT are analyzed, From the view of research and development of the management system, it discusses how to use RTAI/LXRT to realize hard real-time control of critical mission and how to manage real-time and non real-time tasks. The ultimate realization of the multi-task flight simulation management system has a good performance in real-time control, the biggest single step deviations of critical tasks in 1 ms, 5 ms, 10 ms cycle simulation are all less than 30 ms.
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Computer Engineering. 2008, 34(19): 264-265,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.090This paper proposes a Web-based cluster management tool——Cluster Web Management System(CWMS), which can make administrator control and manage the clusters easier. After analyzing the system architecture of clusters, it presents a new framework of cluster management system based on Web. By using the communication protocol and broadcasting module, server can manage and control cluster agents. Experimental results show that the tool greatly improves the management efficiency, and reduces the difficulty and complexity of cluster management.
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Computer Engineering. 2008, 34(19): 266-268. https://doi.org/10.3969/j.issn.1000-3428.2008.19.091
To solve the problem that learners are unable to get personalized instruction, an improved algorithm is proposed for constructing self-organized communities. This algorithm adopts P2P architecture, and strengthens connections between learners with similar interests based on improved Hebbian learning law. In this way, community structure is adjusted automatically, organizing learners with similar interests together eventually. Experimental results show that compared with traditional Hebbian-based P2P algorithm, this algorithm achieves better construction quality and higher construction speed.
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Computer Engineering. 2008, 34(19): 269-270,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.092Based on introducing the design and management of real-time database system and history database system, this paper presents design and implementation of monitor software of wireless logging. Object-oriented technology is utilized to carriy out the monitor software of wireless logging with Visual C++. To assure its efficiency, the software adopts key technologies such as multithreading, ActiveX data object and double buffers.
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Computer Engineering. 2008, 34(19): 271-273,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.093A method for using the Itanium 2 performance counters for bottleneck analysis is very complex and inconvenient. To cover this shortage, new model based on pfmon is proposed to monitor the performance issues in programs by using the “bubble” counters for stall analysis. The Codemon derived from the model is designed and implemented. In additions, the tool is used to characterize an application named “BNLAG2D”, the results can tell user what about this program is and how to improve the performance. Performances achieved is 15 percent higher than the original program.
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Computer Engineering. 2008, 34(19): 274-276. https://doi.org/10.3969/j.issn.1000-3428.2008.19.094To improve the feeling of immersion in the virtual reality operation system of some type missile, this paper proposes the human-computer interaction environments based on data-glove and orientation tracker. It discusses the structure and the principle of this system, presents the geometry modeling of virtual hand with reference to the structure and movement property of the hand, and adopts the object-oriented technology to show the data. The collision detection problem is efficiently solved by adopting the method of placing transparent bounding volume. The vision and force feedback after the collision are also studied. This system improves the efficiency in the virtual reality operation training of some type missile.
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Computer Engineering. 2008, 34(19): 277-279,. https://doi.org/10.3969/j.issn.1000-3428.2008.19.095The deficiency of the current customization system is analyzed, and a new visual customization system based on Web is provided using product family model technology for the instance of the switch product customization. Problems such as inefficient compatible, not enough flexibility and terrible real time are solved within this system. The theory of product family for data organization and product configuration based on multi-view is presented. Design process and management tool are implemented. The efficency of this system is proved by practices.
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Computer Engineering. 2008, 34(19): 280-282. https://doi.org/10.3969/j.issn.1000-3428.2008.19.096This paper designs Broad-Storage TV(BSTV) system on the hardware platform of Cable Television(CATV) broadcasting network structured in laboratory. Uniform Content Locator(UCL) information is marked on the programs at the services. The storage processes are added to the clients and the clients utilizes the marked information to locate the program contents. The system realizes broadcasting transmission of double-way digital TV programs and incremental download at the client. Experimental results demonstrate the feasibility and validity of BSTV system structured on the platform of CATV broadcasting network.
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Computer Engineering. 2008, 34(19): 283-封三. https://doi.org/10.3969/j.issn.1000-3428.2008.19.097The large-scale weather radar data obtaining, processing and quickly display analysis is very important in nowcasting warning. This paper gives a method to study nowcasting warning system from the system requirement, design and realization. It introduces the design of communication system and workstation, and use of data compression technique. It uses the geographic information system to solve the problem of image animation and registration, and uses multi-threading method to solve real analysis requirement in large-scale process. Experimental results show that the system is very good in real time. It can satisfy the need of business.
2024
Volume 50 No 4
Volume 50 No 4
(Started in 1975, Monthly)
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428