05 February 2007, Volume 33 Issue 03
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Computer Engineering. 2007, 33(03): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2007.03.001It is a key issue for ontology development to acquire domain information hidden in legacy systems by reusing the existing design knowledge. This paper, taking relational database as example, analyses how to identify the information about the structure of relational schemes in legacy systems, presents 12 transformation rules, according to which terms and relations between them can be obtained from the relational schemes in reverse way. And uses the extension entity relationship (EER) diagram to further get semantic information from relational schemes for refining ontology model.
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Computer Engineering. 2007, 33(03): 4-5. https://doi.org/10.3969/j.issn.1000-3428.2007.03.002Linear complexity and kerror linear complexity of the stream cipher are two important standards to scale the randomicity of key sequences. In this paper, for the period length 2pn(p>3), where p is an odd prime and 2 is a primitive root modulo p2, the upper bound on the minimum value k for which the kerror linear complexity is strictly less than the linear complexity is further analyzed and this upper bound can be reached mostly for the period length 2p is proved.
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Computer Engineering. 2007, 33(03): 6-8. https://doi.org/10.3969/j.issn.1000-3428.2007.03.003The SoC design methodology introduces new testing challenges, and test access becomes a key demand for IP core test reuse. Transparency based test access mechanism may impact the test coverage of original circuits. This paper analyzes the fault stimulation and propagation conditions so as to conclude the testability impact of gate-level transparency paths construction, to the stuck-at fault coverage. Fault coverage can be calculated through the introduced testability analysis without extra fault simulation. The experimental results show the effectiveness and accuracy of the fault testability analysis and fault coverage evaluation.
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Computer Engineering. 2007, 33(03): 9-11. https://doi.org/10.3969/j.issn.1000-3428.2007.03.004In the study of digital watermark channel capacity, the known probability distribution is supposed for watermark attack channel, but it is not always true, for example channel estimation errors, scaling and geometrical transformations etc. This paper proposes mathematical model for time-varying watermark channel with side information, composed of the deterministic and the random components of the time-varying attack. Minimal assumptions are made regarding the probability distributions of the watermark channel. Lower and upper bounds on the mutual information between the received signal and the cover signal allows to estimate capacity of watermark channel. Therefore, simple additive Gaussian noise channel model is not sufficient to describe the watermark channel. The theoretical results is valid by numerical simulate.
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Computer Engineering. 2007, 33(03): 12-14. https://doi.org/10.3969/j.issn.1000-3428.2007.03.005The crossed cube proposed by Efe is a variation of hypercube, but some properties of the former are superior to those of the latter. The messages are simultaneously transmitted on some internally node-disjoint paths in the high performance parallel computing system, thus the lengths of those paths directly affect the performance of parallel computing. This paper proposes a parallel routing algorithm with time complexity of o(n2) for crossed cube networks, which can output three paths P0,P1,P2 between the source node u and the destination node v, such that: (1)|P0|=the distance between u and v; (2)|Pi|≤the distance between u and v+3. Therefore, the algorithm works efficiently in communication.
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Computer Engineering. 2007, 33(03): 15-17. https://doi.org/10.3969/j.issn.1000-3428.2007.03.006An immune learning algorithm using real numeric code is proposed aiming at problems about anomaly detection. The constringency condition and astringency of the algorithm is studied. A method of calculating reasonable initial population of antibodies is proposed. A Reasonable range of some main parameters is presented. The experimental result indicates that the algorithm can realize optimization to distribution situation of the antibodies and clustering of data modes. High veracity of anomaly detection is obtained.
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Computer Engineering. 2007, 33(03): 18-20. https://doi.org/10.3969/j.issn.1000-3428.2007.03.007This paper designs and realizes the adaptive shot segmentation algorithm. The shot change types and the factors that affect the accuracy are classified. And the complicated situation is considered as a classification problem. Every level classifier may choice suitable algorithms to distinguish one class from the other. Then they are organized into a tree-like classifier and make the performance of system better. The results of experiments on four advertisements prove that this new adaptive algorithm can acclimatize itself to various situations to detect both abrupt shot changes and gradual shot changes and reduce effectively false rate on the basis of ensuring hit rate.
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Computer Engineering. 2007, 33(03): 21-23. https://doi.org/10.3969/j.issn.1000-3428.2007.03.008Applying GA in automatic test cases generation, followed is the main work: (1)Using control flow path table to analyze the relation between test cases and the executing path; (2)Implementing the GA for automatic test cases generating which is path-oriented, and proving this method can accomplish the equivalent-class subdividing in all the test cases set; (3)In the point of statistics to analyze the error-detecting capability of this method; (4)Doing experiment for validating, which shows a far better performance than a random way.
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Computer Engineering. 2007, 33(03): 24-26. https://doi.org/10.3969/j.issn.1000-3428.2007.03.009A congestion avoidance mechanism based on bandwidth estimation in MANET networks is proposed. In order to get the metric of congestion degree, the available bandwidth is estimated through the work status of wireless link that is monitored by the node continuously. The congestion control mechanism is implemented according to packet type. The bandwidth estimation needn’t exchange information with other nodes, so the overload of system is low. The results of simulation show that the mechanism has better performance.
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Computer Engineering. 2007, 33(03): 27-28. https://doi.org/10.3969/j.issn.1000-3428.2007.03.010Unified modeling language (UML) has been the facto standard for objected-oriented analysis and modeling design. The modeling result based on UML is static description for the command, control, communication, intelligence (C3I) system, but the essence of C3I system is dynamic. Colored Petri net(CPN) possesses strongly descriptive capability and rigorous mathematics foundation and many analytical method, and it is also able to be emulational. The method that is able to be used for logical, behavioral and performance evaluation of architecture from UML artifact mapping to CPN is put forward. Model of the general description based UML is established. The executable model that is established by mapping from UML to CPN is followed to set forth at length. The C3I models of photoelectric interferential system can be well and truly evaluated by simulation of the executable models of CPN.
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Computer Engineering. 2007, 33(03): 29-31. https://doi.org/10.3969/j.issn.1000-3428.2007.03.011Special purpose processors, such as DSPs, can only support limited data types in their instruction sets because they are suitable to specific applications. In programs written in high-level language, if special data types which can not be supported by target processor are used, compiler must translate such statements into instructions supported by target processor while keeping original semantic. One method is presented to deal with specail data types in a VLIW DSP compiler, including code annotation of intermediate representations containing special data types, data flow and scheduling dependency computation, and register allocation improvement. To realize the method, only little modification of compiler is needed, and the method is efficient.
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Computer Engineering. 2007, 33(03): 32-34. https://doi.org/10.3969/j.issn.1000-3428.2007.03.012To detect scanning network worm attack, failed connection flow(FCT) time series is established based on characteristics of worm attack, and a novel approach for worm detection based on energy features of FCT time series and support vector machine (SVM) is proposed. By computing the energy associated with each wavelet packet of FCT time series, this approach transforms the FCT time series into a series of energy distribution vector on frequency domain, then detects the worm using a SVM classifier. The experiment shows that the approach can detect worm attack effectively. Compared to theoretic value, the false positive rate is lower than 6%, and the false negative rate is lower than 1%.
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Computer Engineering. 2007, 33(03): 35-36. https://doi.org/10.3969/j.issn.1000-3428.2007.03.013This paper presents a fast Gaussian computation algorithm based on subspace clustering of embedded speech recognition system to reduce the computation complexity. This algorithm does not need re-training model parameters. The experiments on embedded system show that the speed can be improved by above 20% and the recognition rate does not degrade much.
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Computer Engineering. 2007, 33(03): 37-39. https://doi.org/10.3969/j.issn.1000-3428.2007.03.014A WSTB-based algorithm for similarity search is proposed which is based on the piecewise linear representation to solve the high-dimensional time series searching. The subsequence bin for time series is built and then the index of the bin is built. The distance of the given sequence and similar sequence is calculated. The weighted coefficient for every sequence is decided on the character. So the inquiry can be implemented without checking the content of the bin. The quantity of the WSTB calculation which is gotten from compare one by one is avoided. The searching efficiency can be improved obviously. The currency and efficiency of the algorithm is proved with high-dimensional flight data in this paper.
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Computer Engineering. 2007, 33(03): 40-42. https://doi.org/10.3969/j.issn.1000-3428.2007.03.015This paper describes a heterogeneous multi-processor complier Shangri-la which constitutes a uniform compiler back-end based on whirl2c. By address translation it resolves the problem of pointer sharing arose by different access memory methods. By these techniques Shangri-la integrates two kinds of processors to work on the same compiler. This uniform compile platform sets programmers free from traditional fussy network programming.
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Computer Engineering. 2007, 33(03): 43-44. https://doi.org/10.3969/j.issn.1000-3428.2007.03.016When the requested objects cannot be found in the Web cache and Web cache is full, the removed objects are determined by the efficient cache replacement policy to achieve fewer removals and higher cache utilization. This paper proposes a new and efficient cache replacement policy to improve the processing performance and enhance the quality of service (QoS) on the Web servers. The results of experimentation show that this formula can achieve both document hit rate and document byte hit rate.
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Computer Engineering. 2007, 33(03): 45-47. https://doi.org/10.3969/j.issn.1000-3428.2007.03.017This paper presents the parallel search tree based on attribute set division (PST-ASD). It divides the attribute set into two attribute subsets, and constructs a parallel search tree (PST) respectively on these two attribute subsets. When matching an event, it gets the matching subscription sets from the two search trees respectively, and then gets the finally result by intersecting these two sets. Analysis and experiments show that PST-ASD takes on much less store space and in certain conditions takes on less matching time, especially in the condition that the average number of branches following each tree node is large while the number of matching branches is small.
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Computer Engineering. 2007, 33(03): 48-49. https://doi.org/10.3969/j.issn.1000-3428.2007.03.018Aimed at the multiple model problem of data mining, the theory and technology of combination model is discussed and the application of combination theory to the nearest neighbor is studied. The paper proposes an algorithm of MNN (multiple nearest neighbor) classifiers using a random subset of attributions. With the simple voting method, the multiple nearest neighbor classifiers are combined via a random attribution set and the output of the multiple NN classifiers is combined. The method of MNN can improve on the classification precision. Comparing the MNN method to NN-ECOC, two strongpoint are obtained: (1)MNN is a more simple method; (2)MNN is not limited by multiple classes.
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Computer Engineering. 2007, 33(03): 50-52. https://doi.org/10.3969/j.issn.1000-3428.2007.03.019A preemptive rate-based batching approach is proposed based on the characters of the data stream. A query plan is a sequence of operators. Operators in a query plan are divided into different operator units, which are given different priorities in the scheduling strategy. To improve the efficiency of the continuous query, the approach is preemptive and operator units’ priorities are changed while the system factors alter. Some experiments prove that the approach can not only improve the system’s performance, but also decrease the average latency time of tuples and improve the output rate of tuples greatly.
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Computer Engineering. 2007, 33(03): 53-55. https://doi.org/10.3969/j.issn.1000-3428.2007.03.020At present, the performance of Java virtual machine in Linux NC is relatively low. An optimization is researched and developed, which applies and improves the direct threaded interpreter. In this way, considered the conditions of hardware and software, the executing efficiency of Java VM can be upgraded. Meanwhile, the cost of CPU and memory can be decreased. Thereby, the performance of Java virtual machine can be meliorated.
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Computer Engineering. 2007, 33(03): 56-58. https://doi.org/10.3969/j.issn.1000-3428.2007.03.021Schedule is the top risk of software project, hence, it is a common focus on attention of customer and supplier. The schedule management mechanism of software project is described. The main six schedule tracking methods of software project used in the history such as milestone schedule, man-made activity schedule, working unit progress, earned value, gantt chart and network chart are compared and explained. Every method and its characteristics are described by explaining its calculation formulas, application time, application performance, evolution and other aspects. The best solution of schedule tracking of software project is recommended.
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Computer Engineering. 2007, 33(03): 59-61. https://doi.org/10.3969/j.issn.1000-3428.2007.03.022The problem of incremental update of MFI is introduced, and corresponding algorithms, FAUMFI, is proposed. The algorithm makes full use of a built-up BitMatrix and MFI, thus it can maintain and update MFI efficiently. The execution of algorithms is illustrated.
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Computer Engineering. 2007, 33(03): 62-64. https://doi.org/10.3969/j.issn.1000-3428.2007.03.023As the key underpinning software for high level architecture (HLA) simulation systems, the software quality of RTI is decisive to the simulation systems. The quantity of RTI can be guaranteed basically by software test roundly. The test of KD-RTI sorftware is introduced roundly from the functional (performance) index, test methodology and analysis of test results, including function test and performance test. The performance test of KD-RTI is major. Under the same test environment configure, partial test results of the pRTI by Sweden and RTI1.3NG-V6 by DMSO are also presented to compare. The results show that the KD-RTI software not only meets software performance requirements, but also can be used in generic real time simulations. And the KD-RTI has some performance virtues, such as fast data-exchange velocity, low data loss and low latency.
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Computer Engineering. 2007, 33(03): 65-66. https://doi.org/10.3969/j.issn.1000-3428.2007.03.024The traditional k-means algorithm has sensitivity to the initial start center. To solve this problem, a new method is proposed to find the initial start center. First it computes the density of the area where the data object belongs to; then finds k data objects all of which are belong to high density area and the most far away to each other, using these k data objects as the initial start centers. Experiments on the standard database UCI show that the proposed method can produce a high purity clustering result and eliminate the sensitivity to the initial start centers.
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Computer Engineering. 2007, 33(03): 67-69. https://doi.org/10.3969/j.issn.1000-3428.2007.03.025According to the specialty of automatic transformation from model to code in MDA, this paper proposes a method to transform association in UML class diagrams to code based on MDA. It discusses the association in UML and its two implementation patterns. For every pattern, it defines a suit of rules, which are used in transformation from UML model(PIM) to Java model(PSM), respectively. It presents two transformation examples of implementation pattern by using rules.
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Computer Engineering. 2007, 33(03): 70-72. https://doi.org/10.3969/j.issn.1000-3428.2007.03.026Based on the generalization characteristic of genetic algorithm(GA) and the credit evaluation model, this paper presents a GA-based credit scoring model, and then improves the algorithm. In order to meet the demand of the model match, chromosome express method, the fitness function using right and wrong rate of discriminating two class customer and corresponding genetic operators are designed. The results show that the proposed method is effective and of great practical value.
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Computer Engineering. 2007, 33(03): 73-75. https://doi.org/10.3969/j.issn.1000-3428.2007.03.027The file system based on database has characteristics of file system and database. But the traditional file system interfaces are not compatible with it. In order to resolve this problem, this paper introduces how to port a file system based on database to linux operating system, including its design and implementation. Keeping compatible with the conventional file system interfaces, this solution enhances new file system with some file system features based on database.
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Computer Engineering. 2007, 33(03): 76-78. https://doi.org/10.3969/j.issn.1000-3428.2007.03.028To evaluate job schedule on computational grids, the model of grid workload is constructed. On different nodes, job runtimes are different. Between different nodes, the costs of job migrations are different. Thus, the pure runtime and the pure migration cost are defined, which are independent of the performances of grid resources. The distributions of parallel degree, pure runtime, and arrival interval are obtained from workload models of parallel computers. Besides, the distributions of submittal location, pure migration cost, estimate factor of pure runtime, and deadline are constructed. Application instances show various workloads can be obtained from the model of grid workload to support comprehensive evaluation of job scheduling.
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Computer Engineering. 2007, 33(03): 79-81. https://doi.org/10.3969/j.issn.1000-3428.2007.03.029Based on the problems of the implementation for Max-Min fair rate allocation algorithm in layered multicast and the problems of synchronization points optimization in layered multicast protocol strategy, a REM-assisted scheme of traffic control is devised. The synchronization points strategy of layered multicast, the rate allocation algorithm satisfying Max-Min fairness and the explicit congestion notification technique based on REM are combined together in this scheme. The results of simulation experiments show that this scheme can improve the effectiveness of layered multicast’s traffic control mechanism and the sensitivity to the changes of the network condition with the precondition of intra-session fairness and inter-session fairness guaranteed.
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Computer Engineering. 2007, 33(03): 82-84. https://doi.org/10.3969/j.issn.1000-3428.2007.03.030This paper presents a VNC based NMS integration method that provides the open GUI translation for different NMS systems through the WSRFB protocol. In order to integrate the various NMS systems into a unified network management system, the GUI window sizes and positions of the NMS in the graphic frame buffer are transmitted with the WSRFB protocol. The proposed method is applied in practical telecommunication NMS integration. The experimental result indicates that the method has an important application value in NMS integration and offers the great flexibility in NMS integration.
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Computer Engineering. 2007, 33(03): 85-87. https://doi.org/10.3969/j.issn.1000-3428.2007.03.031Real time multimedia transport protocols in wireless-wired hybrid network are facing new challenges. On the basis of extensive study of characteristics of wireless-wired hybrid network and the current TFRC mechanism, this paper proposes a new TCP-friendly rate control mechanism for real-time traffics. The new mechanism uses Jitter ratio as the signal to differentiate congestion losses and wireless link losses to adjust TFRC’s rate control algorithm. Extensive simulations on NS-2 verify that the new mechanism has better performance than TFRC as well as keeps reasonable friendliness to TCP flows.
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Computer Engineering. 2007, 33(03): 88-90. https://doi.org/10.3969/j.issn.1000-3428.2007.03.032This paper discusses the design of integrated anycast routing protocol and its implementation under Linux. The process of IARP, the format of IARP message, the dynamic updating of MAP table information and anycast data flow information are presented under Linux kernel by modifying the IP protocol stack. And anycast group management system is introduced. Furthermore, the implementation of IARP is used in an real soft router. Finally, it shows an application example where IARP communication is used to distribute load among a set of servers.
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Computer Engineering. 2007, 33(03): 91-93. https://doi.org/10.3969/j.issn.1000-3428.2007.03.033The influence of capture effect on saturation throughput of distributed wireless ad hoc network is investigated. The capture probabilit y of ad hoc networks whose nodes are uniformly distributed is obtained. With certain capture probability, the saturation throughput of 802.11 DCF is also derived.
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Computer Engineering. 2007, 33(03): 94-96. https://doi.org/10.3969/j.issn.1000-3428.2007.03.034ISP management system is implemented for ISP distributed management in next generation network. The innovative aspect of the ISP management system is the integration of centralized and distributed management model by the multilevel JMX concept and multi-functions agent. This work presents a feasible and effective solution for distributed system management with good scalability, consistency, security and heterogeneity. Furthermore, ISP management system implements multi-servers’ load balance, and for which a new algorithm is proposed. This algorithm can adjust servers’receiving weights rapidly to a good state. Experimentation results verify that the customized arithmetic allows ISP to reduce the services’ average response time.
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Computer Engineering. 2007, 33(03): 97-98. https://doi.org/10.3969/j.issn.1000-3428.2007.03.035This paper proposes a new Ad Hoc routing protocol based on AODV. Because the wireless channel is a broadcasting channel and there are many redundancy links in Ad Hoc networks, it designs the routing mechanism to make hosts to learn routing information and repair the broken route quickly.
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Computer Engineering. 2007, 33(03): 99-101. https://doi.org/10.3969/j.issn.1000-3428.2007.03.036This paper puts forward a kind of IP layer multicast congestion control algorithm according to hop to hop, and proves its usefulness based on mathematics, proves the STSR congestion control algorithm has a smaller congestion probability under the buffer area sharing than separating on the information frames transmit under the different priority policies, the STSR congestion control algorithm responding sensitively to network congestion and having larger networks throughput. It simulates the STSR model with NS-2, proving the STSR algorithm can ensure the TCP friendly and realize the distributed control theory of coarser granularity. This conclusion has great realistic significance to the multicast congestion control research.
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Computer Engineering. 2007, 33(03): 102-104. https://doi.org/10.3969/j.issn.1000-3428.2007.03.037In the context of computer networks, most conventional algorithms are designed to network under no-failure conditions, but the troubles of network are not taken into account. This paper presents a hybrid approach of genetic algorithm to form the initial network, which has hops and edge-connected constraints, and then analyses the network behavior after failure. To the change of the flow due to failure, it presents a heuristic algorithm to make local improvement for network. Using the method, it makes a new routing after a link failure to search for saturation links, then to add links to reduce the flow load of the rest links, finally to delete the leisure links or links with lower using rate to reduce the cost of network. Simulation results show the effectiveness of the method.
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Computer Engineering. 2007, 33(03): 105-107. https://doi.org/10.3969/j.issn.1000-3428.2007.03.038The characteristic of an application level multicast routing model is analyzed, which is structured based on overlay network. A new application level multicast routing algorithm with degree and average delay constrains is advanced based on clonal strategies. Simulations show that compared with those based on genetic algorithm, the application level multicast routing based on clonal strategies has faster converging speed and better ability of global searching with property of stabilization, agility and operating simply.
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Computer Engineering. 2007, 33(03): 108-110. https://doi.org/10.3969/j.issn.1000-3428.2007.03.039It becomes a critical issue to access and quantify the availability of most networks. This paper presents a novel framework to access the availability of end-to-end traffic in the optical transport network. In this framework, the end-to-end traffic is analyzed by serial structure and parallel structure. It just focuses the ring network availability based on SDH technology that has self-healing mechanism. Calculation of availability is made using the failure of optical cables and equipments that are obtained during years-long observation. At last, the applicability of this framework is also examined in actual networks.
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Computer Engineering. 2007, 33(03): 111-113. https://doi.org/10.3969/j.issn.1000-3428.2007.03.040Unstructured P2P networks are more scalable and more effective than centralized networks. How to locate resource rapidly and effectively in unstructured P2P networks becomes a key issue. Bittorrent is a simple, effective P2P file sharing system, but it only solves how to download effectively while how to locate resource is still unsolved. This paper presents a P2P distributed search method(IHS) based on bittorrent P2P network in order to improve its search ability. It implements a simulation program and tests the performance of the system. Experimental results show that IHS is an effective method with high recall rate and low resource usage.
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Computer Engineering. 2007, 33(03): 114-115. https://doi.org/10.3969/j.issn.1000-3428.2007.03.041It is currently an important research direction of network computing to build a dynamic non-dedicated cluster by using idle processors on a LAN. The most important issue of non-dedicated is the dynamic variety of network flow and communication delay. It is a major problem to induce the computing instability. This paper tries to analyze theoretically and estimate the influence of network flow to the various parallel tasks running in a non-dedicated cluster. The typical measurement results are provided.
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Computer Engineering. 2007, 33(03): 116-118. https://doi.org/10.3969/j.issn.1000-3428.2007.03.042The paper analyses QoS requirement of different services in broadband wireless system. The method of service-simulation is proposed to test QoS of a network. Based on detail discussion on the service-characteristic parameters, the VoIP traffic pattern is simulated by Ixia testing device. A real test on Wimax device is carried out using the simulated traffic. Compared to the method based on real-service, this method has such advantages: quantity measurement, generality, flexibility.
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Computer Engineering. 2007, 33(03): 119-121. https://doi.org/10.3969/j.issn.1000-3428.2007.03.043An optimization scheme to AODV protocol through path collection is examined and proposed. This scheme adopts the path collection mechanism in DSR protocol to improve the performance of AODV, meanwhile it avoids being affected by the high running overhead and weak scalability of DSR protocol. Results obtained by Network Simulation (NS) shows that the optimized AODV scheme performs effectively in terms of packet delivery ratio, routing overhead and end-to-end delay.
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Computer Engineering. 2007, 33(03): 122-124. https://doi.org/10.3969/j.issn.1000-3428.2007.03.044This paper presents a mobile IPv6(MIPv6) testbed, which is built in a LAN. Handover of mobile node(MN) is implemented by re-partitioning VLAN in switches, which is different from traditionally using “pull out and plug in” of cable or modification of wireless ESSID. The organization, handover implementation and control program of the testbed are introduced. Emulation results show that compared with traditional handover methods, the VLAN-partition based method is more convenient and faster.
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Computer Engineering. 2007, 33(03): 125-127. https://doi.org/10.3969/j.issn.1000-3428.2007.03.045This paper presents tunnel proxy mechanism that acts as a proxy for main tunnel protocols and monitors tunnels in the whole course of tunnel lifecycle. Two tunnel proxy models are proposed. The first one is the traditional tunnel proxy model and the second one expands the first one. A framework of tunnel proxy system is presented and several components in this system are defined, such as access policy database, access control server, system log, tunnel information database and tunnel proxy server. In comparison with tunnel technology and proxy technology, tunnel proxy mechanism provides more security.
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Computer Engineering. 2007, 33(03): 128-130. https://doi.org/10.3969/j.issn.1000-3428.2007.03.046Based on simulation analytical method, this paper systematically investigates the performance of series of recent AQM (active queue management) schemes designed for buffer management at routers in the Internet. According to their design principles, AQM schemes are classified into three categories: AQM based on queue length, network load, and a combination of them. Simulation investigation and analysis illustrate that existing AQM schemes are not adaptive to dynamic network traffic.
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Computer Engineering. 2007, 33(03): 131-132. https://doi.org/10.3969/j.issn.1000-3428.2007.03.047This paper introduces the model of communication between multi-task based on VxWorks RTOS. The model is based on UDP transmit mode and the concept of virtual device. It overcomes the defects of the old communication theory and can satisfy the real-time performance and system resource requisition of the RTOS. It analyses the principle, possibility and superiority of the model. Specific implementation is show in the end of the paper.
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Computer Engineering. 2007, 33(03): 133-135. https://doi.org/10.3969/j.issn.1000-3428.2007.03.048To improve reality, usability and efficiency of simulation, this paper designs a large-scale, parallel and distributed network simulation system. It can use the actual data from network measurement tools as the base of simulation; partition the network with an optimized goal; by using BGP-like router configuration, it can provide correct and quick remote router simulation; with a script-generator, related simulation scripts can be automated generated. Many security events can be simulated by this system, such as worm diffusions and DDoS attacks, etc.
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Computer Engineering. 2007, 33(03): 136-137. https://doi.org/10.3969/j.issn.1000-3428.2007.03.049For the load-balance cluster system connected by a switch, this paper proposes moving the load-balance function to the real-server nodes, so that there is no need for a load-balancer. And real-server nodes will backup each other. When one node fails, another backup node will take over its work. As a result, it realizes a high-availability and load-balance Linux cluster system without a load-balancer.
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Computer Engineering. 2007, 33(03): 138-140. https://doi.org/10.3969/j.issn.1000-3428.2007.03.050This paper presents a routing algorithm based on mobile agent to block the wormhole attacks in Ad Hoc network. Traversing over the whole network, a few mobile agents communicate with each node to collect the network connection information to build the global information matrix of nodes by which data packets are determined to be routed and transferred according to a breadth_first search algorithm. Experiment is done in simulated environment of NS-2 system. Having the global information matrix in its cache, every node is familiar with the geographical position of other nodes in the network to defend the wormhole attacks efficiently. This approach needs fewer moving agents to get more global information. Therefore it reduces the overhead by only maintaining the routing information on each node. It is very efficient and robust to transfer packets rapidly.
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Computer Engineering. 2007, 33(03): 141-143. https://doi.org/10.3969/j.issn.1000-3428.2007.03.051Login is an important process for user authentication. Some P2P systems, however, still use concentrated control model to implement login process because this process usually involves some sensitive data such as username and password. This paper describes a model for distributed login based on CHORD, and uses many methods such as split encryption, independent backup and profile take-over to improve the security and reliability. This model has great significance in reducing the running cost and solving the force-out of concentrated login server.
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Computer Engineering. 2007, 33(03): 144-146. https://doi.org/10.3969/j.issn.1000-3428.2007.03.052In order to improve the precision of Web discovery, a method named IWD(immunity-based Web discovery) for Web discovery is proposed. Mathematical formulas of self, non-self, antibody and antigen for Web discovery are established, and implementation of the method is described. The compared experimental results show that IWD has the ability of self-learning, higher precision and better time efficiency than the technique based on neural network does.
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Computer Engineering. 2007, 33(03): 147-148. https://doi.org/10.3969/j.issn.1000-3428.2007.03.053This paper presents a new adaptive digital audio watermark method based on discrete wavelet transform and discrete cosine transform. The watermark is embedded into the audio signal by modifying some of its coefficients in DWT domain. The selection of the coefficients is based on the time domain masking of human auditory system (HAS). Initial results obtained show that the watermarked signal is indistinguishable and satisfactory robustness against various common attacks.
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Computer Engineering. 2007, 33(03): 149-150. https://doi.org/10.3969/j.issn.1000-3428.2007.03.054This paper studies the security of key establishment and management protocol of IEEE 802.11i 4-way handshake, and it is found that there exists security vulnerability, which will lead to a DoS attack. Based on the study, an improved method to enhance the security of IEEE802.11i 4-way handshake is developed.
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Computer Engineering. 2007, 33(03): 151-153. https://doi.org/10.3969/j.issn.1000-3428.2007.03.055RFID brings in security and privacy hidden trouble because of its wireless communication mode and no demand for visibility, a new approach——key value renewal random lock is proposed based on the analysis of some kinds of typical methods. Through taking in the random hash lock with one-way Hash function, renewing the tag’s key value in each communication process and encrypting the data transported between tags and reader by Hash function, this approach efficiently prevents unauthorized reading, location track, wiretapping, counterfeit and spoofing, replay attack and so on. Analysis shows that this approach is low-cost, forward secure, low-load, high efficiency, good security and fits for the scenario when the tags number is large.
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Computer Engineering. 2007, 33(03): 154-156. https://doi.org/10.3969/j.issn.1000-3428.2007.03.056The realization of stateful inspection technic and the security requirements of FTP, Web and E-mail services are proposed. On the base of the above analysis, the adoption of application level protocols analysis on stateful inspection firewalls with its implementation on Linux is discussed. It turns out to make stateful inspection firewalls to have more control on application level protocols.
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Computer Engineering. 2007, 33(03): 157-159. https://doi.org/10.3969/j.issn.1000-3428.2007.03.057MIKEY is a protocol specification for group registration protocol that can be used for real-time multimedia applications. This paper analyzes the key generation, distribution mechanisms of MIKEY, designs a group registration protocol, MIKEY-PKGRP, based on the public-key mode and MIKEY specification. Finally, it analyzes the security of MIKEY-PKGRP with BAN logic deduction.
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Computer Engineering. 2007, 33(03): 160-162. https://doi.org/10.3969/j.issn.1000-3428.2007.03.058Based on neural network classifier of multilayer perceptron and Bayesian classifier of probability prediction, the classification method is given of system call short sequence of description system process behavior, to identify whether the system call is normal or not in the performance process of monitor system key programs. The running and monitor problems of many system key programs in the system are researched and IDS prototype is put forward based on process behavior classifier. Based on system configuration, the system prototype can monitor the performance of many system key programs in the system.
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Computer Engineering. 2007, 33(03): 163-166. https://doi.org/10.3969/j.issn.1000-3428.2007.03.059A probabilistic model which based on probabilistic model checking is proposed for a ε-fair non-repudiation protocol. According to entity’s various behaviors, finite state automaton models are established. Using probabilistic model checker PRISM verifies viable, ε-fair and time-bounded of probabilistic non-repudiation protocol. With malice entity’s ability and network environment various conditions, probabilistic distribution of protocol’s fairness being destroying is analyzed.
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Computer Engineering. 2007, 33(03): 167-168. https://doi.org/10.3969/j.issn.1000-3428.2007.03.060The paper presents a new kind of analysis method for computer system survivability which considers both exterior environment and interior components and their correlations. The method can describe the survivability more precisely and exactly. The priority using this method to security evaluation is also put forward.
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Computer Engineering. 2007, 33(03): 169-171. https://doi.org/10.3969/j.issn.1000-3428.2007.03.061This paper reviews and analyzes WLAN’s new generation of security standard IEEE 802.11i and the 4-way handshaking protocol. With the analysis to this practical protocol, the paper indicates the vulnerability on 4-way handshaking and the possible attack. After reviewing the proposed solution of 802.11i standard, the paper analyzes its incompletion and vulnerability, and gives out two schemes of improvement design, a TPTK random-drop queue to the supplicant, and adding authentication to the initial message. In the end, system validating and analysis are made.
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Computer Engineering. 2007, 33(03): 172-174. https://doi.org/10.3969/j.issn.1000-3428.2007.03.062This paper describes an automatic prediction model of Chinese prepositional phrase boundary location based on HMM. It consists of two stages: automatically identify the phrase boundary using statistics from treebank, then, post-tune the results with dependency grammar knowledge generated by dependency treebank. Experimental results demonstrate a high rate of success for predicting boundary location (86.5% correct rate for close testing and 77.7% for open testing).
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Computer Engineering. 2007, 33(03): 174-176. https://doi.org/10.3969/j.issn.1000-3428.2007.03.063This paper issues about the requirements of different format pictures fitting to various mobile phones in the environment WAP explorer. The structure designed and implemented in the article is a self-adaptive way of image show for WAP by the technology of JAI, and some relative performance is discussed. The model can be applied to WAP application, and the structure has some adaptabilities and general to some extend.
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Computer Engineering. 2007, 33(03): 177-179. https://doi.org/10.3969/j.issn.1000-3428.2007.03.064This paper introduces the design and implementation of an automatic processing software system for LAMOST celestial spectra. Some key algorithms in the system such as covering algorithm, wavelet transform, mean shift, etc., are also presented. The experiment results over the datasets of sloan digital sky survey (SDSS) show that this system has good characters in processing speed, classifying accuracy and redshift measuring precision. And the implemented system is workable for the large survey projects.
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Computer Engineering. 2007, 33(03): 180-182. https://doi.org/10.3969/j.issn.1000-3428.2007.03.065The sequence model of population evolution of mind evolutionary algorithm is built up by analyzing the ‘similartax’ and ‘dissimilation’ operators and the evolutionary process of multilayer populations. Based on the property of sequence limit, the algorithmic convergency is studied and the global convergency is proved. Finally, the experimental results according with the above conclusion are gained.
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Computer Engineering. 2007, 33(03): 183-185. https://doi.org/10.3969/j.issn.1000-3428.2007.03.066This paper is made on some existing problems with the realization of WebGIS. By analysis of the deficiency in the design of conventional WebGIS, the paper imports the Agent technology into WebGIS system. The purpose of the paper is to build an intelligent WebGIS system. After analyzing the function of Agent, it gets the definition of reactive Agent, presents a model of reactive Agent. Based on this reactive Agent, a multi-agent system is proposed, which provides a new method to study and develop WebGIS. The paper gives an application of agriculture WebGIS to explain the function of every reactive Agent in the multi-agent system.
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Computer Engineering. 2007, 33(03): 186-188. https://doi.org/10.3969/j.issn.1000-3428.2007.03.067The time and space consuming in the construction of the suffix array is always the bottleneck in practical uses. This paper introduces two preferable construction algorithms, analyses and evaluates them from performance aspect and points out their applicable scope, gives and compaes experiment results of two algorithms in different condition.
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Computer Engineering. 2007, 33(03): 189-191. https://doi.org/10.3969/j.issn.1000-3428.2007.03.068This paper presents a method of medical image retrieval based on regions of interest and global features. It presents a new region growing algorithm with gray level co-occurrence matrix to extract the focus region, the threshold segmentation is applied to improve the edge of segmented region. In order to avoid the image’s angle difference for the bodily position, the paper uses Zernike moment to extract the global features of the image. It combines the shape and distribution features of the regions of interest with Zernike feature for image retrieval. Experiment results show that the method is much more effective.
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Computer Engineering. 2007, 33(03): 192-193. https://doi.org/10.3969/j.issn.1000-3428.2007.03.069An algorithm of punctuating the sentences in archaic Chinese language based on context n-gram model is proposed in the paper. The algorithm can make comparatively accurate prediction of the punctuating-positions of the text under data-sparse instances by collecting and calculating context information to better analyze small-scaled corpus and meanwhile, to bring down the effects of the data-sparse plight on the global accuracy. At last, the paper selects the analects of Confucius ( Lunyu ) to test the algorithm introduced, and the results show that the recall and the precision achieve 81% and 52% respectively.
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Computer Engineering. 2007, 33(03): 194-196. https://doi.org/10.3969/j.issn.1000-3428.2007.03.070FAS is divided into several parts according to their functions. Each part is modeled with a federation-architecture agent (FAA). An FAA is built up by a mediator agent and some common agents. The system has many advantages, such as: hierarchical framework, intelligence and robustness, tasks are decomposed and carried out and system is easy to model. The involved agents are defined, and their roles in the architecture and the buildup that each agent would need are described. Cooperation mechanism based on bid/mediator or tell/do methods is offered. An experiment is introduced to show the merits and validness of the framework of the FAS.
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Computer Engineering. 2007, 33(03): 197-199. https://doi.org/10.3969/j.issn.1000-3428.2007.03.071This paper proposes a fast and effective method for moving vehicle detection under cloudy conditions. A zone distribution based background estimate model is used to update background and accelerate the background track. It introduces a color image based HSI model to suppress the noise caused by cloud movements, and to improve object detection accuracy. The experiment results show that the algorithm can be adaptive to cloudy conditions and vehicle detection correction rate is up to 80%.
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Computer Engineering. 2007, 33(03): 200-201. https://doi.org/10.3969/j.issn.1000-3428.2007.03.072Convex hull problem is one of the fundamental problems in computational geometry, and is used in many fields. Reference[4] presents an algorithm for finding the convex hull of a simple polygon using active double line test. By presenting counter-examples, it proves that the algorithm could not adapt to all cases, and analyzes its shortcoming, proposes an improved algorithm. The improved algorithm completely solves self-intersection which linear algorithms do not solve, and the realization is simple.
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Computer Engineering. 2007, 33(03): 202-204. https://doi.org/10.3969/j.issn.1000-3428.2007.03.073The mechanism that gives rise to the phenomenon of premature saturation of the output units of BP network from mathematics is described. The theorem for the occurrence of premature saturation is presented and proved. It is concluded that the momentum term plays the leading role in the occurrence of the phenomenon. In addition, the connection between some improved algorithm proposed by some researchers and the conditions of the theorem in this paper is analysed. Therefore, it can provide a good guidance in theory for improving BP algorithm.
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Computer Engineering. 2007, 33(03): 205-207. https://doi.org/10.3969/j.issn.1000-3428.2007.03.074The omitting of misleading actions in the research of previous plan recognition leads the result of recognition in low accuracy in some special domains. In order to solve this problem, new concepts are defined, such as reliability, correlativity, and correlated action sequence etc. And a novel algorithm is proposed to determine whether the action is misleading action or not. It makes use of the results worked out by correlated action sequences. The new algorithm improves the accuracy of plan recognition. Moreover, the prospect of the application of the algorithm is bright in intrusion detection, network security and other domains.
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Computer Engineering. 2007, 33(03): 208-209. https://doi.org/10.3969/j.issn.1000-3428.2007.03.075This paper proposes a novel human face detection algorithm based on real Adaboost algorithm. Policy that calculates in advance the partitioning of Haar-like feature weak classifiers in sample input space and updating training face samples’ weights dynamically is adopted. This algorithm reduces training time cost greatly compared with classical real-Adaboost algorithm. In addition, it speeds up strong classifier converging, reduces the number of weak classifiers and decreases detecting time.
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Computer Engineering. 2007, 33(03): 210-212. https://doi.org/10.3969/j.issn.1000-3428.2007.03.076This paper describes a new information retrieval model semantic information retrieval (SIR) for the semantic Web based on semantic index terms. By using semantic index terms, it can perform the information retrieval and inference based on the semantic relationship in the documents.
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Computer Engineering. 2007, 33(03): 213-214. https://doi.org/10.3969/j.issn.1000-3428.2007.03.077A simulation method of grasping objects in Jack environment and its disadvantage are introduced, and another method for grasp simulation with Jack by detecting collision is put forward, which includes grasp preparing, grasp positioning, and grasp motion executing. The implementation of grasp simulation method can not only overcome the shortcomings of current simulation method, but also can greatly improve the efficiency for user to simulate grasp motion.
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Computer Engineering. 2007, 33(03): 215-217. https://doi.org/10.3969/j.issn.1000-3428.2007.03.078Directshow is now popular StreamMedia system development framework, but the StreamMedia system developed with Directshow has shortage of transplantability, run effiency, stability, expansibility. According to the shortage of Directshow, a new modularized StreamMedia system development framework is designed and implemented. The performance of the StreamMedia system developed with the new framework can be improved.
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Computer Engineering. 2007, 33(03): 218-220. https://doi.org/10.3969/j.issn.1000-3428.2007.03.079This paper analyzes the structure of video transmission over Internet, takes into account of behaviors of encoder, transmission channel and decoder synthetically, and proposes a new approach for optimal mode selection: global R-D optimized mode selection. Be different from local optimized of traditional R-D optimized mode selection, this new algorithm provides the best trade-off between compression efficiency and error resilience in global area, and makes the performance of system to be the best. The experiment results show that integrate with error control and concealment, the approach improves the robust of video data significantly and the video quality in decoder.
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Computer Engineering. 2007, 33(03): 221-222. https://doi.org/10.3969/j.issn.1000-3428.2007.03.080This article introduces the theory, traits and developments of DNA computer, puts forward the importance of micro-flow system in the developments of DNA computer. By discussing investigations of micro-flow system in manipulation and detection of DNA and protein molecular, it proposes that the structure of micro-flow system is tend to be complication and 3- Dimension. The latest evolves of 3D detection under microscope and the disadvantages of these methods are given.
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Computer Engineering. 2007, 33(03): 223-224. https://doi.org/10.3969/j.issn.1000-3428.2007.03.081This paper divides the image into more tiles and array them the frequency and sample, which does well in the video monitor and control. The way which makes data smaller need to be transmitted under the same image quality and realizes the synchronization transmission on remote video stream better. It introduces plus matrix in order to improve response speed, and speeds tiles sampling response to some tiles is varied swiftly by data dictionary.
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Computer Engineering. 2007, 33(03): 225-227. https://doi.org/10.3969/j.issn.1000-3428.2007.03.082Based on the analysis of the difficulties to improve the equipment manufacturer’s services, this paper researches the design of a remote equipment monitoring system based on WebGIS/GPRS/GPS technologies. The server-side WebGIS program is developed in the .NET environment and a GPRS/GPS-integrated module is also developed to transfer the performance data and locate the equipment. The cross-area experiment shows that it is suitable for monitoring the equipments which are in different areas or enterprises and helpful for the manufactures to improve their services and plan the proactive maintenance.
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Computer Engineering. 2007, 33(03): 228-230. https://doi.org/10.3969/j.issn.1000-3428.2007.03.083OPC(OLE for process control) is the co-operational specification between the applications in industrial control. One OPC DA server is implemented for the LonWorks network, which enables OPC clients to locally or remotely access this LonWorks network in an easy way. On the base of the discussion of the implementation principle of the server such as real time database, GUI, OPC objects and I/O read and write and so on, the key technologies such as processing write commands and synchronizing multi-threads are probed.
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Computer Engineering. 2007, 33(03): 231-233. https://doi.org/10.3969/j.issn.1000-3428.2007.03.084FPGA greatly improves the flexibility and universality of electronic system, and is widely used in various fields. However FPGA is sensitive to SEU in aerospace which leading to the destruction of internal user logic. Updating and fault-recovery of system-level are also quite difficult. Based upon this, this paper presents an architecture that detects and corrects the fault of FPGA based upon error diagnosis with a CPLD in aerospace. Meantime, this architecture can also implement reconfiguration and fault-recovery at system-level.
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Computer Engineering. 2007, 33(03): 234-236. https://doi.org/10.3969/j.issn.1000-3428.2007.03.085This paper proposes embedded system for picture flame detection with the core of DSP, aiming at the problems on flame monitoring, temperature field measure and combustion diagnosis. On the basis of temperature field measure principle using color image method, all circuits and system soft of image acquisition and processing are analyzed and illuminated. Though optimum design, system ability of data processing and real-time is heightened heavily. Experimentation of 200MW unit shows that system can accomplish image processing, extract statistic feature within 1 frame time for one picture, and accomplish diagnosis for boiler burning conditions within 1 second. So the real-time of flame detection and burning diagnosis is assured. The maximum error of temperature distribution measure is at range of 50℃ and relative error is less than 5%. Therefore, these can meet the requirement of accuracy measurement.
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Computer Engineering. 2007, 33(03): 237-239. https://doi.org/10.3969/j.issn.1000-3428.2007.03.086Network traffic measurement and analysis are the basis of network traffic behavior research. This paper proposes the design of network traffic measurement that can analyze the flow ingredients by research on RMON2. The problem about physical network topology discovery and the layout of topology map based on Web are discussed. By means of the implementation of this system, it can monitor the network traffic efficiently.
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Computer Engineering. 2007, 33(03): 240-242. https://doi.org/10.3969/j.issn.1000-3428.2007.03.087Radio compass is one of the important airborne equipments and the sequence mensuration of navigation angle is ensured by it. Through the detailed analysis to work principle and key circuit of compass, an integrated design method based on VXI and GPIB instruments technology is presented for radio compass automatic test system. Using this way, ATS with versatility, expansibility and maneuverability is easily implemented. Design of hardware platform of radio compass automatic test system, such as system structure of hardware platform, various adapters, test project is achieved.
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Computer Engineering. 2007, 33(03): 243-244. https://doi.org/10.3969/j.issn.1000-3428.2007.03.088A new method of developing the gateway between TCP/IP network and CAN bus network is described. According to the features of TCP/IP and CAN, the hardware design scheme and software modules are discussed. The described method can be used in any TCP/IP network, not limited to one net type. Compared to the embedded gateway developing method, it is more flexible and general, more easily to develop and maintenance.
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Computer Engineering. 2007, 33(03): 245-247. https://doi.org/10.3969/j.issn.1000-3428.2007.03.089Data mining based on rough set theory in process industry is applied to prediction of product qualities. The original data mining model based on the rough set is improved to be suitable for process industry data that would be of large dimension, complexity and continuous in time. Combined with FCM, a method of data mining technique based on the rough set theory in process industry is designed. The method obtains good performance in the experiment on the real industrial data of a practical acetone refining process.
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Computer Engineering. 2007, 33(03): 248-250. https://doi.org/10.3969/j.issn.1000-3428.2007.03.090Combined design of heat exchanger with computer application technique, taking MDT as development platform, using ActiveX automation interface technique which is united within MDT and VBA development environment, the assembly simulation system of new type high efficient energy saving heat exchanger is investigated and developed, which can reduce design cost, shorten design process, improve the efficiency and quality, accelerate the popularity and application of new product and technique. Crucial techniques of the system are investigated and solved, implemented methods of it are practiced.
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Computer Engineering. 2007, 33(03): 251-252. https://doi.org/10.3969/j.issn.1000-3428.2007.03.091EPIC technology is applied not only to the designs of general-purpose CPU, but also to application specification instruction set processors (ASIPs) in application specific domain. But its high performance is at a cost of sharp expansion of EPIC program code. To solve it, this paper presents a new encoding method——dynamic variable-length encoding. Tests indicate that the method can achieves an average static code compression ratio of 62.8% in speech algorithm of low encoding code.
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Computer Engineering. 2007, 33(03): 253-255. https://doi.org/10.3969/j.issn.1000-3428.2007.03.092This paper proposes a FPGA implementation structure of a fuzzy CMAC. Compared with other neural networks implemented by FPGA, it contains the learning algorithm which can be employed to realize the on-line learning. The model and the relevant hardware modules of fuzzy CMAC are analyzed. It implements the fuzzy CMAC based on the above hardware modules with VHDL. The design is synthesized and tested. The test result shows that the method of the hardware implementation of the fuzzy CMAC is feasible. The implemented network comprises the characteristics of high speed, good precision and little chip resource. It is an effective method in implementing the module of fuzzy CMAC in SOPC.
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Computer Engineering. 2007, 33(03): 256-258. https://doi.org/10.3969/j.issn.1000-3428.2007.03.093Based on the analyses of RS232 and USB’s actuality and develop direction, a method of upgrade RS232 device to USB device is expatiated. A simple and convenient method to design USB device is introduced.
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Computer Engineering. 2007, 33(03): 259-261. https://doi.org/10.3969/j.issn.1000-3428.2007.03.094There are some very complicated problems in the 3D geologic graphing. The paper provides a design and means for solving them, and presents the codes of the 3D graph drawing based on OpenGL in Visual C++. It is proved that the information can been clearly, exactly, and fully obtained with the example of the factor loading 3D graph drawing of the correspondence analysis. The results suggest that the revolving 3D graph can not only obviously excel both 2D dimension graph which presents from only an orientation, and 3D graph which presents from finite orientations, but also the implementation of it can discern the relative space places more properly and easily among different graph elements.
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Computer Engineering. 2007, 33(03): 262-264. https://doi.org/10.3969/j.issn.1000-3428.2007.03.095This paper designs and implements the method of automatic control interfaces generation on information appliances and its corresponding central control mechanism, focusing on IPv6-based UPnP home networks and the important role that the residential gateway plays in the interaction between external networks and home networks: the IPv6-based residential gateway generates a uniform control interface for every information appliance from the template file, after receiving commands external network users submit through the control interface, the IPv6-based residential gateway controls information appliances centrally according to SOAP. The study perfects Internet gateway device(IGD) V1.0.
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Computer Engineering. 2007, 33(03): 265-267. https://doi.org/10.3969/j.issn.1000-3428.2007.03.096To solve the problem of immature application of 3D information system in virtual manufacture, a man-machine interactive 3D transformer substation information visualization system is established through the Extensible-3D(X3D) and Java. The system allows users to manage information in 3D scene and the revised information can be saved to database automatically. The 3D scene can be rebuilt according to the newly database when system resets. An instance has been validated that the system structure has the management traits of interaction and visualization. It changes the traditional mode of information management which uses character and 2D document purely and also can be used for reference to the virtual manufacture.
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Computer Engineering. 2007, 33(03): 268-270. https://doi.org/10.3969/j.issn.1000-3428.2007.03.097Network isolation technology is widely used in protecting some networks on which important information are carried. A proxy method for some popular IM software is proposed in a security isolation system, in order to make it possible that clients in the protected LANs can communicate with other clients outside the protected LANs. MSN protocol is analyzed and a proxy for MSN Messenger in such isolation environment is designed and realized.
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Computer Engineering. 2007, 33(03): 271-272. https://doi.org/10.3969/j.issn.1000-3428.2007.03.098A modified CORDIC algorithm is presented, based on computing the trigonometric function of specific angle, which can be expressed as and used in FFT, upconvert/downconvert and DDS. Simulation results show that the storage unit can be saved and computation efficiency can be increased by about 50% compared with the traditional CORDIC algorithm. Therefore the algorithm is feasible and available.
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Computer Engineering. 2007, 33(03): 273-274. https://doi.org/10.3969/j.issn.1000-3428.2007.03.099The program-aided tools using in developing electronic government system are disrelated each other. This condition often causes discontinuous development and repeated work, and it is very easy to make mistake. To resolve this problem, the design of electronic government system cooperative development platform(EGSCD) is put forward. EGSCD is composed of a work flow model tool, a business rules model tool, a business Web pages design tool and a system running platform. The tools are ideally integrated into one platform to aid programming. Using this platform, programmers can fully use the information got before in the latter development work, increase working efficiency and avoid making some mistakes.
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Computer Engineering. 2007, 33(03): 275-277. https://doi.org/10.3969/j.issn.1000-3428.2007.03.100The feedback controller is a core technique of a scanning probe microscope(SPM), but the feedback of SPM using at the present time is usually based on analog circuit, therefore a feedback based on digital signal processor(DSP) possesses high practical value. Through analyzing of an analog feedback, a digital feedback based on DSP and related hardware and software are developed while the improved algorithm is presented. Experimental tests show that the feedback controller can supply various functions correctly, at the same time, the stability and flexibility of the feedback controller are improved obviously.
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Computer Engineering. 2007, 33(03): 278-280. https://doi.org/10.3969/j.issn.1000-3428.2007.03.101SIP is playing a more and more important role in VoIP as the application-layer control protocols. This paper proposes the implementation of an IP phone server system using the functional plug-ins technology based on the SIP protocol. It introduces the SIP protocol and SIP server components, presents the structure and the thought of implementation of IP phone server which is implemented with the plug-ins technology mentioned above. At last it explains some details of implementing the function of plug-ins.
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Computer Engineering. 2007, 33(03): 281-283. https://doi.org/10.3969/j.issn.1000-3428.2007.03.102For the need in mechanical process of statistical process quality control, the paper analyses the actual applications demand of corporation, and presents a controlling strategy for the system, and has given out a real-time data’s data model, and has built a network structure and a function structure of software for the system. The online quality management information system based on the real-time data is developed, and satisfies the applications demand for the online quality management of the corporation. The function of remote monitoring and controlling based on network is realized. Nowadays this system has been applied successfully in a production lines of a corporation and obtains good application result. There is the reference value for the other corporation.
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Computer Engineering. 2007, 33(03): 284-284. https://doi.org/10.3969/j.issn.1000-3428.2007.03.103Open source database MySQL is more and more widely used by airlines information system. Based on deeply analyzing the characteristic of business data in airlines domain, this paper provides a method of managing airlines fundamental data by means of memory storage engine. This method combines memory-based table with disk-based table, it not only provides good performance, but also solves the problem of memory table’s permanent storage.
2024
Volume 50 No 3
Volume 50 No 3
(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