05 February 2009, Volume 35 Issue 3
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Computer Engineering. 2009, 35(3): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2009.03.001Considering the peculiarity of the control system of 6-DOF(Degree of Freedom) space robot and the influence of space environment, a distributed visual servo control system based on the dual-redundancy technology is presented in this paper. This system mainly consists of main control computer, joint controllers and hand-eye controller. Hot & cold redundancy CAN bus is adopted as the communication bus in the system. The design of every function node is based on the dual-redundancy idea. All function nodes are harmonized by the main control computer. The issues of the space robot include the limited capability of control system, the adaptability in space and the real-time of the communication systems. The feasibility of the design has been validated by the integration and test of the function and capability of the control system.
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Computer Engineering. 2009, 35(3): 4-6,44. https://doi.org/10.3969/j.issn.1000-3428.2009.03.002An asymmetric public-key traitor tracing scheme is proposed based on the bilinear map on elliptic curves. By using the Lagrange interpolation, one-key based one-encryption and multi-key decryption come true. Combining the bilinear property of Weil pairing, given a specially designed input, the pirate decoder outputs the register record of the traitor, via which the new scheme realizes black-box tracing. In addition, this novel work contains other desirable features, such as asymmetry, non-repudiation, revocation property and full frame-proof. The security of the scheme depends on the difficulty of Bilinear Decision Diffie-Hellman(BDDH) problem on elliptic curves.
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Computer Engineering. 2009, 35(3): 7-9,50. https://doi.org/10.3969/j.issn.1000-3428.2009.03.003Referenced presented models of optical flow computing, three models of color image sequence optical flow computation with local and global methods combined for color optical flow computing are presented in this paper. The combined models have the advantages of high precision of local model and density of global model. And the models presented are compared with each other. The number experiments results are presented.
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Computer Engineering. 2009, 35(3): 10-12,1. https://doi.org/10.3969/j.issn.1000-3428.2009.03.004Ray-casting algorithm is a widely recognized method for high quality direct volume rendering, but the speed of rendering is too slow. Therefore, the design of specific hardware architecture based on Ray-casting is a hot research point. But memory system becomes the bottle-neck of the whole architecture and its performance directly affects the running speed of the whole system. This paper designs a conflict-free eight-bank low-order interleaving parallel memory system VOXMEM to increase the throughput, and voxel distribution function and address computation method are also proposed. The parallel memory system is achieved based on page mode SDRAM. Satisfied results are got through the emulation experiment.
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Computer Engineering. 2009, 35(3): 13-14,5. https://doi.org/10.3969/j.issn.1000-3428.2009.03.005To select routing line is very important to save energy in wireless sensor networks. This paper investigates the energy consumption of single-hop and multi-hop routing in wireless sensor networks, and a critical distance is found, under the condition of specified compression ratio or fusion ratio. Multi-hop routing consumes less energy than single-hop routing when the distance transmitting data from node to clustering-heads or base station is no less than the critical distance. The simulation results show analysis done is right and it has application significance to select routing line in wireless sensor networks.
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Computer Engineering. 2009, 35(3): 15-17. https://doi.org/10.3969/j.issn.1000-3428.2009.03.006The blindness is an important property of a proxy blind signature scheme. For their shortcomings of having no blindness about Cai et al’s ID-based proxy blind signature and Hu et al’s ID-based proxy blind signature, two corresponding improved schemes are proposed. It shows that the two improved schemes overcome the disadvantages of the original signature schemes and also retain the merits of them.
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Computer Engineering. 2009, 35(3): 18-20. https://doi.org/10.3969/j.issn.1000-3428.2009.03.007Volunteer computing is a form of distributed computing in which the availability of general public volunteers is regular and periodic. This paper proposes a novel approach based on Hurst’s rescaled range analysis and fractal theory for time series are applied to study the deformation fractal characteristics of the volunteer computing for HPC Project. It is found that the volunteer may be regarded as a non linear dynamic system and the fractal dimension can be used to describe the dynamic variation characteristics of the whole platform and applied to diagnose the probable problem of the availability of node. The approach is implemented and validated on a platform XtremWeb.
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Computer Engineering. 2009, 35(3): 21-22,7. https://doi.org/10.3969/j.issn.1000-3428.2009.03.008One of the Trusted Computing Group(TCG) infrastructure is credential system, which participates in trusted chain of transmission process. Attestation identity credential’s type, the full definition and the relationship to other credential are discussed. Its application on remote attestation is studied. Based on the study, the way to improve the security of Secure Socket Layer(SSL) protocol using trusted computing and AIK credential is put forward for solving the application’s attestation on SSL server.
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Computer Engineering. 2009, 35(3): 23-25,2. https://doi.org/10.3969/j.issn.1000-3428.2009.03.009This paper proposes a learning-based duplication deletion method for structural information on Web. It prepares a training set for producing classifier, classifies different attribute fields of structured information in pages, and computes the distances according to the classifier. The distance between the whole information object and classified sample information is computed, and whether the record is duplicate by comparing with threshold is judged.
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Computer Engineering. 2009, 35(3): 26-28. https://doi.org/10.3969/j.issn.1000-3428.2009.03.010In the process of 3-D inversion of gravity and magnetic anomalies for physical properties with large scale data, the BP inversion algorithm produces huge storage and computation requirement. This paper offers an efficient solution based on the principle of storage equivalent and multi-core paralleled design. It mainly includes applying the principle of storage equivalent to the position function of physical property units to reduce its storage cost, and using multi-core paralleled design to the process of the algorithm to improve its computing efficiency. It reduces the storage cost from O(kn4) to O(kn2) and gets a speedup value of 3.897 on a quad-core server, which is very close to the theoretical speedup value of 4.
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Computer Engineering. 2009, 35(3): 29-31. https://doi.org/10.3969/j.issn.1000-3428.2009.03.011The method to design the Database Management System(DBMS) for marine geological survey is introduced. The characteristic of the general structure, functional modules and database is analyzed, on the basis of which, the main functions of this system are implemented. The method to implement the key functions such as distance and area measures, contours generation, spatial distribution analysis is also discussed. It has certain reference value to similar GIS designs and practice.
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Computer Engineering. 2009, 35(3): 32-35,3. https://doi.org/10.3969/j.issn.1000-3428.2009.03.012The objective of information-sharing mechanism is to joint the database servers and offer service for the external with a unified view. This paper presents a distributed database nodes autonomy sharing model based on data integration theory and blackboard model. Overall pattern, information pattern management and data replication type concept is proposed. It analyzes and realizes the model of the structure and operation mechanism. Its main ideas are useful to the realization of database server groups.
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Computer Engineering. 2009, 35(3): 36-38. https://doi.org/10.3969/j.issn.1000-3428.2009.03.013OWL ontology is widely used in knowledge engineering, which is adopted to solve the problems in software development. This paper analyzes the differences between OWL ontology and Java object-oriented model, points out some problems existed in mapping directly to Java object-oriented model, and expounds the merits of mapping to aspect-oriented model. The method to map OWL ontology to AspectJ aspect-oriented model is also proposed, which implements the mapping to software code model well.
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Computer Engineering. 2009, 35(3): 39-41. https://doi.org/10.3969/j.issn.1000-3428.2009.03.014Influenced by the upgrading of information systems and the booming of Web 2.0 applications, the information inside a modern enterprise is growing explosively. In order to promote the accuracy of searching results in massive information, this paper designs a personalized search system, which uses the traditional information filtering technology such as classification and gathering. The role-based collaborative model is also proposed. Experimental results show this new collaborative model can find out the personalized requirement of enterprise users more efficiently and make the sarech results more accurate.
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Computer Engineering. 2009, 35(3): 42-44. https://doi.org/10.3969/j.issn.1000-3428.2009.03.015Aiming at the problem of synchronization and structure mismatch between data persistence and full text index in the development of Management Information Systems(MIS) based on J2EE, a realizable model based on Hibernate Search is proposed, which includes extension and optimization to modules. This new model is applied in the case of knowledge base, which implements the flexible full text search with high performance. Experimental results show this model can integrate the data information in database and full text index effectively, and promote the efficiency of full text index.
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Computer Engineering. 2009, 35(3): 45-47,4. https://doi.org/10.3969/j.issn.1000-3428.2009.03.016Aiming at the problem that the event flank is restricted by the frame structure in the news information extraction based on event frame, a method of event new flank detection is proposed, which defines two types of event new flank. The LSA clustering detection is implemented by filtering the existed flank content. The word pair feature model is used to take full use of semantic information in content-limited paragraph. This method is tested in prototype system, and experimental results show it is effective.
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Computer Engineering. 2009, 35(3): 48-50. https://doi.org/10.3969/j.issn.1000-3428.2009.03.017In the current SOA implementation, Web services can not collaborate with each other. In order to work collaboratively, the component in the SOA must have the awareness about the activities in the system. This paper adopts an event infrastructure, which introduces the Event Driven Architecture(EDA) into the SOA. This event infrastructure collects execution information of the Web service, uses the complex event processing technology to process this information, and sends it to the SOA component to realize collaborative awareness.
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Computer Engineering. 2009, 35(3): 51-53. https://doi.org/10.3969/j.issn.1000-3428.2009.03.018Frequent patterns mining involves mining transactions, sequences, trees and graphs. This paper presents an efficient pattern growth algorithm for mining frequent embedded subtrees in a forest composed of unordered trees. It uses a canonical method to represent unordered trees in a unique way. It creates a projection database for every growing point of the pattern to grow. The problem is transformed from mining frequent trees to find frequent nodes in the projection database.
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Computer Engineering. 2009, 35(3): 54-56. https://doi.org/10.3969/j.issn.1000-3428.2009.03.019This paper provides a complete overview on survivability index from the aspects of index content, attack phases and evaluating standard. It proposes an index system which can present the survivability, formalizes the index system, and gives the mathematical model of index system. Analysis and validation results show that this index system has the features of standardization and completeness. It is significant to quantitative evaluation for information systems survivability.
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Computer Engineering. 2009, 35(3): 57-59. https://doi.org/10.3969/j.issn.1000-3428.2009.03.020This paper analyzes the relationship between the rate of software fault exposure and software testing times. On the premise of objective and accurate results of reliability testing, several methods of how to reduce the total number of testing times are proposed. Based on the theory of software reliability and software architecture, a quantitative computation method of component-based software failure rate is presented. The efficiency of software reliability testing and the accuracy of reliability estimation are improved by the research of software reliability measurement.
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Computer Engineering. 2009, 35(3): 60-62. https://doi.org/10.3969/j.issn.1000-3428.2009.03.021This paper analyzes and compares several typical P2P streaming media models in expansibility, start delay and system stability. It points out the differences between media service models based on gossip protocol and P2P streaming media service models based on multicast tree protocol, and summarizes the key techniques of P2P streaming media service system, such as data scheme algorithm and peer selection algorithm. It analyzes some existent problems and some remained issues for further research.
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Computer Engineering. 2009, 35(3): 63-65. https://doi.org/10.3969/j.issn.1000-3428.2009.03.022In accordance with the shortcomings in efficiency and security of PayWord, which is a mobile micro-payment protocol based on conventional Hash chains that has a length limit, this paper brings up a new protocol suitable for mobile commerce certification and micro-payment, involving the idea of “multiple denominations” Hash chains, a self-renewal Hash chains scheme and a token-based authentication method. Analysis results show that the protocol has better security, efficiency and fairness, and it is fit for frequent micro-payment between a mobile user and a fixed information service provider.
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Computer Engineering. 2009, 35(3): 66-67,7. https://doi.org/10.3969/j.issn.1000-3428.2009.03.023This paper points out the defect of old algorithm for reduction based on discernibility matrix. Through improving discernibility matrix and the method of measuring attribute significance, a complete heuristic algorithm for optimal reduction based on the absorption law in discernibility matrix is introduced, effectively reducing the space complexity of the algorithms for reduction based on discernibility matrix. Experimental result indicates the reduction got by new algorithm is the same to the approach of discernibility matrix and functions. This conclusion illuminates the new algorithm is valid and complete.
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Computer Engineering. 2009, 35(3): 68-70. https://doi.org/10.3969/j.issn.1000-3428.2009.03.024Aiming at the disadvantages of storing data, checking and transferring in the flow of packet, the technique of storing data with XML data dictionary is brought forward. According to the given datasheets, the data dictionary of XML format is designed. The analysis of data dictionary which is based on XML is implemented, the operations such as storing data, checking or transferring can be done on the visual interface, and the process of storing and transferring is described with class diagram. Results show the convenience of storing of system structure and checking.
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Computer Engineering. 2009, 35(3): 71-73. https://doi.org/10.3969/j.issn.1000-3428.2009.03.025This paper proposes a novel e-learning service discovery algorithm——eLSDAUS. A factor of user satisfaction which is the user’s feelings to the result of service discovery is led-in. This algorithm allows users to take part in the process of e-learning service discovery, and allows them to evaluate the result of service discovery. User’s evaluation is fed back to the system. With the help of penalty function, the system modifies the weight of each property of the advertise service, and then total match degree of service discovery up to best. Experiment indicates that the precision of the service discovery improves 4%~5% as the number of advertisement services up to 10 000. After learning for one week, over 93% students are satisfied with the e-learning service discovery result.
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Computer Engineering. 2009, 35(3): 74-76,7. https://doi.org/10.3969/j.issn.1000-3428.2009.03.026
To ensure Web applications’ reliability, and meet the requirement of the test Web application functionality, this paper presents two improved approaches for using user session data to support those applications from a functional view. These approaches effectively solve the data conflicts which happen during combination of user sessions. Experiment elaborates these approaches and proves their effectiveness in functions and blocks coverage.
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Computer Engineering. 2009, 35(3): 77-79. https://doi.org/10.3969/j.issn.1000-3428.2009.03.027This paper describes how to construct the algorithm for inline data-structure such as function call graph, and presents the inline algorithm based on the function call graph. According to the requirements of KAP system, an inline algorithm for leaf-node is proposed. Testing results indicate that the algorithm can inline efficiently and effectively the functions of NPB testing set. After inlining, the ratio of acceleration can reach 15.78% at most.
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Computer Engineering. 2009, 35(3): 80-82. https://doi.org/10.3969/j.issn.1000-3428.2009.03.028Similar topic detection and topic excursion are two important factors which affect the performance of topic detection. For these two problems, this paper proposes a topic detection approach based on adaptive center vector. By using information of name-entity in feature representation, it combines name-entity vector and keyword vector to construct topic center vector, which can detect similar topic efficiently. Based on the idea of single-pass clustering, the algorithm modifies topic center dynamically. Experimental results show that the algorithm can improve the performance of topic detection effectively.
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Computer Engineering. 2009, 35(3): 83-85. https://doi.org/10.3969/j.issn.1000-3428.2009.03.029The traditional admission control algorithms use the effective bandwidth to calculate the maximal number of the concurrent multimedia applications, but they either do not provide Quality of Service(QoS) guarantee perfectly or do not utility the resource efficiently. This paper establishes a queuing model that describes the concurrent multimedia workloads accessing storage systems, and a statistical admission control algorithm is derived form it. Simulation experiments prove the novel algorithm is accurate.
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Computer Engineering. 2009, 35(3): 86-88. https://doi.org/10.3969/j.issn.1000-3428.2009.03.030Instruction set, as the interface between software and hardware, plays an important role in computer architecture. Random Test Program Generation(RTPG) is one of the efficient ways to verify an instruction set. After comparing some existing RTPG technologies and verification strategies, this paper proposes a library-based RTPG tool for instruction set verification. By developing both library and test template using a general purpose script language, it is capable of generating high quality test in different test stage. Results of test show that it is easy implemented, and on the meantime, it can get a satisfying verification result.
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Computer Engineering. 2009, 35(3): 89-90,9. https://doi.org/10.3969/j.issn.1000-3428.2009.03.031This paper proposes a new method which can extract the useful information from the different document sites automatically based on the breadth of a sub-tree. Experimental evaluation on a large of Web pages from different document Web sites has done and this method has been applied to the platform of gansu science & technology document sharing successfully. Experimental result shows this method automatically extracts the information ignoring where Web sites the pages come from and has high accuracy in terms of recall and precision．
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Computer Engineering. 2009, 35(3): 91-93. https://doi.org/10.3969/j.issn.1000-3428.2009.03.032Based on the parallel optimization of gene computer clone software(SiClone) and alternative splicing analysis software(AltSplice), this paper puts forward a parallel optimization method. It divides needed large-scale sequence database into many segments according to some strategy, therefore each node is responsible for a smaller portion of the database, which eliminates disk I/O and heavy communication demands and much more fits for low-cost and efficent Linux clusters architecture.
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Computer Engineering. 2009, 35(3): 94-95,1. https://doi.org/10.3969/j.issn.1000-3428.2009.03.033This paper focuses on Graphical User Interface(GUI)’s automatic test. The most difficult thing is test case generation. This paper adopts a new technique to test GUIs automatically. It describes GUIs with Hierarchical Finite State Machine(HFSM), and then the work is converted into the consistency testing of the expected HFSM and the actual HFSM. It searches GUIs’ controls initiatively and automatically, and generates the tesing data with ‘uniform design’ method. Testing data drive the test to be executed. According to the characteristics of GUIs, this paper adopts incremental mode to construct the model and to do test, to avoid error accumulation.
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Computer Engineering. 2009, 35(3): 96-98,1. https://doi.org/10.3969/j.issn.1000-3428.2009.03.034A method of estimating Direction Of Arrival(DOA) based on Multistage Weiner Filtering(MSWF) is proposed. Rough estimation of DOA is provided by testing orthogonality between estimated signal subspace and noise subspace and gets more precise results through testing cross-correlation function of MSWF. Simulation shows that the proposed method offers improvements in estimation performance under low SNR condition compared with the previous algorithm.
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Computer Engineering. 2009, 35(3): 99-102. https://doi.org/10.3969/j.issn.1000-3428.2009.03.035Along with rapid development of IPTV, the IPTV user will increase continually, IPTV managers advise new demand about the existing devices, based on the solutiont of Access Convergence Router (ACR) of National 863 Plan, this paper presents a scheme of the channel zapping supporting the increasing IPTV subscriber, designs the FPGA program. Performance simulation results indicate that this scheme can fulfill the requirement of the increasing IPTV subscriber .
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Computer Engineering. 2009, 35(3): 103-105,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.036On the base of underlying encapsulation for I/O Completion Port(IOCP), this paper presents a design solution with high performance and scalable module of generic network communication, which emploies a variety of optimization techniques of system performance, such as thread pool, object pool and ring buffer. The module is developed in C++ programming language on Win32 platform. Experimental results show that the module can support massive concurrent connections, and has higher data throughput based on severe pressure and performance tests. The proposed solution has also got a good performance in the actual project application.
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Computer Engineering. 2009, 35(3): 106-108,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.037This paper proposes LBFS mechanism based on BFS to solve the scalability and detouring problem in existing P2P search approach. A P2P search model named light-weight hybrid model is designed. The algorithm validity in LBFS is proved and its efficiency is analyzed. Experimental results on LBFS and model showt that the model has better performance and scalability by avoiding detouring problem and reducing message redundancy.
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Computer Engineering. 2009, 35(3): 109-111. https://doi.org/10.3969/j.issn.1000-3428.2009.03.038While largely developed independently of each other, P2P overlay networks in Internet and Mobile Ad Hoc Networks(MANET) share many key characteristics such as self organization and decentralization. This paper provides an overview of existing service discovery approaches in MANET. In order to overcome their drawbacks, it presents a structured P2P system R-CAN to reduce routing hops in MANET, and the entire system consists of a set of regions where peers are in proximity. Experimental results show that R-CAN can greatly enhance the system performance and effectively reduce the routing hops.
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Computer Engineering. 2009, 35(3): 112-114. https://doi.org/10.3969/j.issn.1000-3428.2009.03.039With the spread and applications of wireless sensor network in the coal mine, the request is pointed out to connect wireless sensor network with Ethernet which is the trunk network under the mine. The gateway is one of the most important parts. By analyzing communication reality methods of wireless sensor network to Ethernet, the blue print of gateway based on high performance network controller and embedded real-time operating system is pointed out. The key techniques and methods on how to realize the gateway with embedded microprocessor S3C4510B and embedded real-time operating system VxWorks are expounded.
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Computer Engineering. 2009, 35(3): 115-117. https://doi.org/10.3969/j.issn.1000-3428.2009.03.040The paper introduces the SyncML protocol, focuses on the implementation of a data synchronization system which is based on SyncML protocol, combines the features of the client and server, and gives the idea of the implementation. The client(mobile phone) uses the development language of J2ME. The server uses the tomcat which is based on the J2EE architecture and the free open-source project of the Funambol data synchronization architecture, and analyses the function and characteristics of the implementation and the virtue of ideas.
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Computer Engineering. 2009, 35(3): 118-120. https://doi.org/10.3969/j.issn.1000-3428.2009.03.041Aiming at the question of MANET’s real and fake congestion, this paper puts forward three types of non-congestion control and four types of bringing the package error. Adopting universal arithmetic and recognition sequence, gives the particular value to map NET_ERR0, and starts interrelated error recovery arithmetic. This paper resolves the influence of real and fake congestion. The simulation approves that the recognition sequence greatly reduces the times of congestion.
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Computer Engineering. 2009, 35(3): 121-122,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.042A highly clustered scale-free network model is studied in this paper. Based on HK model, local behaviors of HK model have been improved by adding dynamic link that the new vertex should have. By analyzing and imitating it makes clear that not only the improved model can inherit the characteristic of highly clustering coefficient and scale-free from HK model, but also the degree exponent of the model can change between 2 and 3. Competition among all network vertexes is close to real-life society.
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Computer Engineering. 2009, 35(3): 123-125. https://doi.org/10.3969/j.issn.1000-3428.2009.03.043Based on linear distribution, multi destination nod and bidirectional information transfer of freeway weather monitor wireless sensor network, this paper proposes a bidirectional routing protocol based on directed diffusion. The simulation proves that this bidirectional routing protocol is easy to be implemented and stable in working, and it can satisfy the demand of bidirectional information transfer of freeway weather monitor wireless sensor network.
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Computer Engineering. 2009, 35(3): 126-129. https://doi.org/10.3969/j.issn.1000-3428.2009.03.044An efficient implementation of inter-AS Border Gateway Protocol(BGP)/Multi-Protocol Label Switching(MPLS) in high-performance router is presented. It decomposes forwarding functions in specification and distributes them in main controller and forwarding engine. The main controller takes charge of label distribution and management. The forwarding engine encapsulates and forwards MPLS packets. A recursive lookup during the procedure of forwarding Visual Private Network(VPN) packets is avoided by pre-processing label information in control panel and the forwarding hardware only needs to lookup table once. The forwarding speed can get line rate.
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Computer Engineering. 2009, 35(3): 130-132,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.045The existing network topology discovery methods require intact routing information, but a lot of routing information lack instances in network make them fail. Based on R&D of a network management system called SeeLink NMS, this paper detailedly expounds detecting, analyzing and resolving of the problem. And it presents routing device detecting idea, researches and implements a network topology discovery method aiming at routing information lack. Testing and applying prove that the method can resolve routing information lack problem, and it can accurately and entirely discover the whole network topology structure even if the network is not able to provide intact routing information. The method is valuable to be applied and popularized.
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Computer Engineering. 2009, 35(3): 133-135,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.046This paper analyzes the most popular Peer-to-Peer(P2P) software currently, BitTorent(BT) working methods, and finds that the content distribution algorithm makes document fragments distribute uneven among the network nodes, which impacts on the efficiency of the system. It proposes an algorithm to control the content distribution of the seeds. This algorithm can effectively avoid the document fragments to be distributed uneven in the network, so that all nodes have the similar number of fragments. This paper compares the new system with the old system from the aspects of distributed time, content diversity of the nodes and average download time of all the nodes. Simulation results show that the new system reduces the average download time and improves the robustness and efficiency of the whole system.
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Computer Engineering. 2009, 35(3): 136-138. https://doi.org/10.3969/j.issn.1000-3428.2009.03.047With the development and interconnection of satellite networks, wireless networks and other heterogeneous network, the TCP performance of current widespread use is greatly affected in the network environment of a long delay and high bit error rate. This paper studies the congestion control and congestion restoration strategy of PEP with TCP Selective Acknowledge(SACK) protocol and proposes a PEP SACK congestion control algorithm that does well on improving performance of TCP in a long delay and high bit error rate of the network environment, based on the theoretical model that installing a Performance Enhancing Proxies(PEP) of transmission control functions at the border of heterogeneous network.
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Computer Engineering. 2009, 35(3): 139-141. https://doi.org/10.3969/j.issn.1000-3428.2009.03.048Network bandwidth is affected severely because IPSec VPN gateway needs complex cryptographic transformation. This paper puts forward a parallel processing model for IPSec based on multi-core processor. In this model, IPSec packets are assigned to different processor units, so the network bandwidth can be improved. In addition, this model is implemented on Linux operating system. After performance testing, the IPSec VPN gateway which has a dual-core processor gains near double improvement.
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Computer Engineering. 2009, 35(3): 142-144. https://doi.org/10.3969/j.issn.1000-3428.2009.03.049Bluetooth specification can not supply users with the solution to construct bluetooth scatter net. This paper adopts the idea that scatter net should be formed based on the capabilities of devices, and presents a new scatter net construction algorithm. The algorithm chooses devices with great capabilities to act as master and bridge, and takes measures to control the number of Pico nets, roles acted by devices, M/S bridges. It is proved by performance analysis that the algorithm can distribute appropriate roles according to the capabilities of devices, and has good performance in a few parameters.
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Computer Engineering. 2009, 35(3): 145-147,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.050Accumulation of node localization error and distance measurement(or calculation) error between nodes restrict the benefit of iterative refinement of node localization in Wireless Sensor Networks(WSN). In order to improve the precision of node localization effectively, this paper proposes a hop-refinement and relative confidence based on Weight Least Square(WLS) algorithm. Hop-refinement increases redundancy for node location. Relative confidence declines accumulation of error. Application of hop-refinement in robust positioning algorithm brings forward RP-Hop algorithm. Simulation results show that localization precision increases by 10% compared with Robust Positioning algorithm.
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Computer Engineering. 2009, 35(3): 148-151. https://doi.org/10.3969/j.issn.1000-3428.2009.03.051This paper proposes a distributed fault tolerance unicast routing algorithm based on the concept of k-E-2DMesh subnet and local information. It applies probabilistic analysis on the fault tolerance of this algorithm. Supposing each node has an independent failure probability, it is able to derive the probability that the routing algorithm successfully returns a fault-free routing path. Discursion result show that when the value of k is 3, the routing algorithm succeed in finding a fault-free routing path with probability at least 99% as long as the node failure probability is bounded by 0.03%. This algorithm runs in liner time, and its length constructed by the algorithm is close to the optimal length between 2 nodes.
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Computer Engineering. 2009, 35(3): 152-154. https://doi.org/10.3969/j.issn.1000-3428.2009.03.052This paper analyzes USB protocol and wireless communication protocol, and introduces a protocol model on application layer aiming at the application of wireless 2.4 GHz USB device. This model realizes the communication between one slave and multi master. It improves the DSSS mechanism and independent communication channel mechanism to reduce noise and conflict during communication. An application example using Cypress CYRF6936 and Freescale MC68HC908JW32 MCU is realized.
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Computer Engineering. 2009, 35(3): 155-157. https://doi.org/10.3969/j.issn.1000-3428.2009.03.053The algorithm of LEACH is an important technology to reduce energy consumption. It can enhance the network scalability and extend survival time of the network. LEACH-C is a special edition of LEACH. It is a centralized algorithm to produce cluster heads which are chosen by base station. But every node sends its datum to the cluster heads by just one hop, these cluster heads send their gathered datum to base station by one hop too. That leads to overload of cluster heads. In order to solve problem, a new protocol adopt cluster heads multi-hop algorithm based on LEACH-C is proposed. In this protocol, an optimal path is formed among cluster heads which lead to path. Experimental result indicates that the new algorithm is very energy-efficient, and it can prolong the lifetime of the sensor network.
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Computer Engineering. 2009, 35(3): 158-160,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.054This paper proposes a novel amendatory DRR scheduling algorithm for the satellite onboard switch due to the limitation of the satellite load procession speed and memory capacity, and builds the model of Low Earth Orbit(LEO) satellite constellation switch. In addition, it simulates the performance of the amendatory DRR algorithm in the modeled switch using OPNET. Simulation results demonstrate that the proposed algorithm is suitable for the LEO satellite onboard switch. Even the traffic is heavy, the scheduling algorithm can ensure that the traffic is intact, and the switch delay is lower than 10 ms and the complexity is O(1) when the satellite onboard switch resource is limited.
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Computer Engineering. 2009, 35(3): 161-163,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.055ZigBee focuses on short-haul, low data rate. The mesh routing protocol for ZigBee is built on the AODV, adopting an effective routing protocol and reducing overhead for route discovery may interfere with network traffic. Based on the ZigBee mesh network, this paper improves AODV route protocol, and proposes a new AODV_Cluster rouote protocol. AODV_Cluster divides the ZigBee network topology into one or more logical clusters. A cluster label uses the ZigBee address allocation, and the one cluster can share a new routing. Simulation shows this protocol not only keeps the AODV merit, but also advances the scalability. Especially in dense network, its performance excells AODV.
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Computer Engineering. 2009, 35(3): 164-165,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.056This paper proposes a halfway filter method to filter IP source address spoofing based on scale free property of Internet. Compared with the existing StackPi method, the great advantage of the method is that it only needs to deploy less than a tenth part in 100 of the nodes to efficiently suppress IP source address spoofing. The premise of the method is to accurately locate the hub by acquiring the topological property of Internet or by some algorithm that can locate the hub.
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Computer Engineering. 2009, 35(3): 166-168. https://doi.org/10.3969/j.issn.1000-3428.2009.03.057Cryptanalysis of a group signature scheme based on Chinese remainder theorem shows that it exists security flaws. Aiming at these flaws, this paper puts forward an improved group signature scheme. It realizes effective participation and revocation of group members under the condition that keep the group member secret key unaltered. Analysis results show that this scheme is secure and practicable.
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Computer Engineering. 2009, 35(3): 169-172. https://doi.org/10.3969/j.issn.1000-3428.2009.03.058This paper presents a buffer overflow detection model based on intermedia assembly which can be used to perform static analysis and detection on executable files. The algorithm is transparent to hardware platforms, the code is better readable, and buffer overflow is easy to detect. For the 2 string copying operations, i.e. insecure function invokes and copying memory loops, it researches buffer overflow caused by the later and present a flow sensitive and context-insensitive algorithm to detect it.
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Computer Engineering. 2009, 35(3): 173-175. https://doi.org/10.3969/j.issn.1000-3428.2009.03.059It is difficult to detect Internet worm in LAN, because of the similarity of probing mechanism between the P2P and internet worm. This paper proposes a detection algorithm names D-ID3 that is based on danger theory and ID3 classification algorithm. The entropy theory is used to analyz P2P application, worm, natural mainframe, and extract axis attributes. ID3 and danger theory are applied to get classification rules that can differentiate worm, P2P and natural traffic. Experimental results show that this algorithm can detect worm and P2P successfully with a low false alarm rate.
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Computer Engineering. 2009, 35(3): 176-178. https://doi.org/10.3969/j.issn.1000-3428.2009.03.060Focused on the mobile Web Services’ security issues, this paper proposes the application layer’s security assurance by using XML encryption and signature. This method affectes the system’s efficiency. It achieves an optimized implementation by using WAP’s optimized encoding and proprietary transmission protocol. Experiments considering the aspects of dealing time and spending show that, the efficiency is greatly improved and the security is not affected.
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Computer Engineering. 2009, 35(3): 179-181. https://doi.org/10.3969/j.issn.1000-3428.2009.03.061This paper dicusses the issues of authentication mechanism and framework of the digital signature system. Based on the analysis of the security gap in the authentication mechanism using digital signature, a novel authentication system combining asymmetric key cryptography and multiple watermarks technique is proposed. A robust watermark and a semi-fragile watermark are embedded in the information to carry out the functions of ID authentication and data integrity authentication. Illegal access to system, edition, and forgery of information is proven to be impossible. According to the analysis, the system’s structure is simple and the security, creditability, and authenticity are achieved.
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Computer Engineering. 2009, 35(3): 182-185. https://doi.org/10.3969/j.issn.1000-3428.2009.03.062Aiming at the shortage of Role Based Access Control(RBAC) model on efficiently assigning a role for the user and assigning permission for the role and permission allotment want for context constrain, this paper puts forward Organization Based Access Control(OBAC) model. It increases organization concept on the RBAC foundation and lowers many complexities that assigning role for user in the classes organization. According the organization to definite entity and relation, the efficiency leads to raise role permission an assign into the abstract concept of the object and action, and defines the context entity to carries out the permission constrain.
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Computer Engineering. 2009, 35(3): 186-188. https://doi.org/10.3969/j.issn.1000-3428.2009.03.063Risk evaluation for mobile commerce reputation system is a complicated system issue. After analyzing indexes of information system risk evaluation and characteristics of mobile commerce reputation system, this paper presents three core indexes and puts forward a mobile commerce reputation system model which is simple, flexible, and utility. A mobile commerce reputation system is given to illustrate the availability and the reliability of the model.
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Computer Engineering. 2009, 35(3): 189-191,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.064The advanced encryption standard is the mainstream encryption algorithm in the security network protocol used in Linux system. Through analysis of AES encryption algorithm, with the architecture characteristics of the Loongson platform, the method for performance optimization of AES based on the expansion of multimedia instructions (SIMD technology) is proposed. Before and after optimization, the results of data transmission using security file transfer protocol Sftp (AES encryption) shows that the Loongson SIMD optimization has reduced the time of encryption and decryption and has effectively improved the Sftp network transmission rate.
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Computer Engineering. 2009, 35(3): 192-194. https://doi.org/10.3969/j.issn.1000-3428.2009.03.065Aiming at the security of agent-based distributed cooperative intrusion detection framework that suits hierarchical Mobile Ad Hoc Networks(MANET), this paper extends the distribute cooperation IDS, puts forward an agent-based intrusion detection system for classified MANET. The system adopts cooperation detection method of clusters, and provides further intrusion detection scenario for protecting hierarchical MANET. Detailed analysis and simulations are carried to validate the effectiveness of our detection model for attacks.
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Computer Engineering. 2009, 35(3): 195-198. https://doi.org/10.3969/j.issn.1000-3428.2009.03.066This paper presents a new efficiency evaluation methodology of Distributed Denial of Service(DDoS) attack and defense mechanisms based on strategic game. Aiming at rate-limiting defense mechanisms in current DDoS defense strategies, it proposes a game theory method to model DDoS attack and defense systems, and evaluates LACC and Pushback mechanisms’ efficient quantitatively, which results in an efficient analysis for defense performances of different strategies in different attack scenarios. This paper uses network simulation tools to implement simulating experiments under typical DDoS attack scenarios, and validates the applicability of the method through computing both players’ mixed strategy Nash equilibriums.
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Computer Engineering. 2009, 35(3): 199-201,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.067This paper proposes an anaphora resolution of noun phrases based on Support Vector Machine(SVM). Evaluation on the MUC-6 corpus using several widely used features shows that the system achieves the F-measure of 68.6% and outperforms other similar systems. Further analysis shows that appositive, name alias and full string matching contributes most for anaphora resolution. It also shows that the distance between the antecedent candidate and the anaphor is very useful in constraining the instance generation, although including it as a feature does not help for anaphora resolution.
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Computer Engineering. 2009, 35(3): 202-204. https://doi.org/10.3969/j.issn.1000-3428.2009.03.068Moving object tracking is a key problem in computer vision and has many applications in various fields. This paper proposes a collaborative tracking method based on Co-Training frame work. The method fuses information from two types of features space to describe the object. The model is updated with Co-Training, which avoids the error accumulation problem. The experiment demonstrates the performance of the method under complex scenarios.
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Computer Engineering. 2009, 35(3): 205-207,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.069This paper proposes a debris flow hazard assessment system of Tianshan road based on ArcEngine component tools and .Net platform. The system integrats the theoretics of neural network and GIS in the process of debris flow regional hazard evolution, plays powerful management of spatial information visualization and analysis functions, and makes it available of the depicting the nonlinear phenomena by BP neural network to the assessment processing of debris flow regional hazard, actualizes the visualization management of debris flow regional hazard evolution and provids stronger decision support scheme to both the policymakers and managers.
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Computer Engineering. 2009, 35(3): 208-210. https://doi.org/10.3969/j.issn.1000-3428.2009.03.070This paper proposes a human face shape matching based on shape context useing shape context algorithm. In the shape matching of the two targets similarity comparison, the focus of this approach is to use the shape context algorithm to calculate log-polar coordinate histogram Cost value, the calculation of similarity to the pre-set thresholds to determine whether his face matcheds. Experimental results show that the algorithm in two-dimensional targets in the invariance has accurate matching results
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Computer Engineering. 2009, 35(3): 211-213. https://doi.org/10.3969/j.issn.1000-3428.2009.03.071This paper discusses the problems in current matching methods of similar records, and proposes an improved method of machine learning. Similar records are clustered to generate a committee of decision tree learners. The committee actively chooses the most informative similar records for users to distinguish between duplicate and non-duplicate records. Those pairs of records are used to train the committee. The matching rules of multiple data source are automatically learned. Experiments on real data show that this method effectively reduces the number of training instances, and achieves high matching accuracy.
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Computer Engineering. 2009, 35(3): 214-216. https://doi.org/10.3969/j.issn.1000-3428.2009.03.072The face recognition algorithms based on SVD have low recognition accuracy due to the common essential defect which singular value vector of arbitrary two face images have the different basis spaces in general. According to this, two improved class estimated basis space singular value de-composition methods are analyzed. A superior CSVD method is selected after comparing with each other. And in the feature extraction process, a new face recognition method based on CSVD and non Negative Matrix Factorization(NMF) is presented. By combining both methods, for ORL database, the better recognition performance is obtained.
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Computer Engineering. 2009, 35(3): 217-218,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.073In order to solve the disadvantages of inaccuracy and subjective error in tradition manual core location, a novel automatic core location method is proposed. The automatic core location of sonic logging is realized by Particle Swarm Optimization(PSO). There are relativities between the sound wave and physical data at the same deepth. According to this theory, the core location can be considered as optimization problems that the global displacement is the smallest while the trend of numerical value is the best fitted. Simulation results show that the automatic core location can be achieved prompt effectively through the particle swarm optimization algorithm.
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Computer Engineering. 2009, 35(3): 219-221. https://doi.org/10.3969/j.issn.1000-3428.2009.03.074Optimizing the order picking is an important strategy to improve the working efficiency of automated warehouse. According to the requirements of order picking tasks of the fixed shelve, a mathematic model is constructed. An improved ant colony algorithm for the order picking problem is designed. Three improvements are adopted: awaiting nodes set, selection operator and dynamic change on algorithm parameters. Simulation results demonstrate the approach has better overall search ability and quickly astringency, satisfying the demands of medium or large scale work.
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Computer Engineering. 2009, 35(3): 222-224. https://doi.org/10.3969/j.issn.1000-3428.2009.03.075Image is analysed under multi-scale filtering in Canny algorithm frame. Scale multiplication is defined by filter responses multiplication of two different scales. The modulus and orientation is determined by the similarity of adjacent scales. A threshold value is chosen to eliminate false edge. The edge is obtained after non-maximum supression. Experimental results show the superior performance of the proposed algorithm in noise restrain and edge localization than the traditional Canny algorithm.
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Computer Engineering. 2009, 35(3): 225-226,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.076The zoom of the images is implemented by using B-spline with the character of the image outline angular point. The mosaic position is found through template matching. The computation of template matching algorithm is simplified by using wavelet transform, which enhances its noise-immune ability. Experimental results show the calculation speed and the mosaic effect of this algorithm are both well.
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Computer Engineering. 2009, 35(3): 227-229,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.077Based on Sugeno fuzzy integral and soft-multi-structural elements, new filter and edge detection are presented. Color image pixels are sorted by the value of Sugeno fuzzy integral. Comparing with other structural elements, soft-multi-structural elements are better on the noise restrained. Morphological transform based on the ranking of Sugeno fuzzy integral can get better results than based on the ranking of HSV. Experimental results demonstrate that the ability of color processing based on the new morphology is superior to the classical one, and that the algorithm possesses excellent performance on the noise restrained.
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Computer Engineering. 2009, 35(3): 230-232. https://doi.org/10.3969/j.issn.1000-3428.2009.03.078Aiming at the problems such as complex calculation, long executive time, and worse practicability when using image segmentation method to seek threshold, a novel 2D maximum entropy image segmentation method is proposed, which uses Quantum-behaved Particle Swam Optimization(QPSO) algorithm to conduct global search of 2D image threshold space, and takes the gray scale value of pixel and the gray scale mean value of region corresponding to 2D maximum entropy value as the threshold for image segmentation. Experimental results show this method has some advantages in aspects of executive time and astringency.
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Computer Engineering. 2009, 35(3): 233-234,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.079Considering the distribution of impulse noises of color images, a two steps algorithm is proposed. The algorithm uses spike statistical detection to detect noise pixels, and rebuilds image using adaptive median filter. Experimental results show that the proposed algorithm works effectively in denosing high level impulse noises although the noise density is higher than 80%, compared with other existing algorithms. It is suitable for online processing tasks, as its lower time-cost.
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Computer Engineering. 2009, 35(3): 235-236,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.080This paper proposes an improved method based on robust M-estimator for global motion. The algorithm adopts statistically robust M-estimator target function on image pixel residual, weighted-function is simplified as binary function. It improves the method of elimination noise points. Experimental results show that the improved algorithm can get high precision and robust with various image sequence, and attain computationally saving.
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Computer Engineering. 2009, 35(3): 237-239. https://doi.org/10.3969/j.issn.1000-3428.2009.03.081One of the main problems related to global motion estimation is that the algorithm only considers the change information in the difference image, but the import information of segmentation and correlation has been ignored. To overcome such drawbacks, a technique of global motion estimation based on MAP is proposed. The system energy is defined through MAP and the potential energy is defined by segmentation mask and the prior information. Using the system energy as object function, the global motion is estimated. Experimental results confirm the effectiveness of the proposed technique.
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Computer Engineering. 2009, 35(3): 240-241,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.082Audio-video synchronization is the key technology in applications such as digital TV broadcasting and multimedia communication. This paper proposes an audio-video synchronization method based on AVS and embedding technique. It embeds compressed audio data into AVS video coding system to keep synchronization all the time between audio and video during transmission or storage, decoding at the receiver and playback. Experimental results show that this method can achieve synchronization between audio and video, and reduce overhead for synchronization.
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Computer Engineering. 2009, 35(3): 242-244. https://doi.org/10.3969/j.issn.1000-3428.2009.03.083This paper researches the shot detection of the video indexing problem, analyzes the cause of the error detections of shots, presents a new robust method based on normalized frame difference of gray distribution for shot detection with adaptive threshold. Experiment results demonstrate that it achieves high accuracy for shot detection with adaptive threshold.
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Computer Engineering. 2009, 35(3): 245-247. https://doi.org/10.3969/j.issn.1000-3428.2009.03.084Video transcoding is emerging as a key technology to provide video streaming service for mobile devices on wireless networks when using video sources from broadband IPTV. This paper designs and develops a software implemented real-time video transcoding system which can convert high bit-rate, high resolution MPEG-4 video sources to low bit-rate, low resolution video in real-time to support video streaming over mobile networks. An adaptive transcoding scheme with delay guarantee is proposed in the paper based on the well-known drift compensation transcoding architecture. This scheme not only leverages the computation complexity and video quality but also ensures the extra delay caused by transcoding process. Experimental results illustrates that the system can achieve real-time transcoding with little quality degradation.
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Computer Engineering. 2009, 35(3): 248-250,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.085The temperature of water tank is measured on real-time by using the new kind of Single-Chip Computer(SCM) STC12C5412AD and thermo-esistances of high sensitivity. The real-time monitoring, controlling, displaying and over-limit alarming are implemented by employing A/D device of 10 digits integrated in the computer for the transformation of analog and digit. The hardware of the system consists of the main computer, power source, button and display, temperature-controlling process, and serial interface communication. The software of the system consists of the modules such as main program, temperature measurement and transformation, temperature-controlling, and etc. The real temperature is transformed and the set temperature in the nixie tube is displayed and altered arbitrarily with the button. Experimental results show this system is of high accuracy in measurement and rapidity in response, which has the value of applications.
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Computer Engineering. 2009, 35(3): 251-253. https://doi.org/10.3969/j.issn.1000-3428.2009.03.086In order to reduce the cost and promote the application of Structural Health Monitor(SHM), a scheme for Remote SHM of Application Service Provider(ASP) mode(ASP-RSHM) is presented. By integrating the relevant resources, the remote professional services are provided to SHM. Combined with the requirements of this system, the method for its implementation based on grid technology is discussed, and the flow of the system is also analyzed. A practical case for application is proposed, which takes Dongting Lake Bridge as the example. Experimental results show this scheme is feasible.
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Computer Engineering. 2009, 35(3): 254-256. https://doi.org/10.3969/j.issn.1000-3428.2009.03.087This paper proposes a random access scan and test approach, which deals with the compatible issue of scan unit to produce new test group. Combined with the structure character of Random Access Scan(RAS), this new test group is optimized, which solves the problems such as test data volume, test power dissipation, and test time. This approach is tested in ISCAS’89 benchmark circuits. Experimental results show this approach is effective and feasible.
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Computer Engineering. 2009, 35(3): 257-259,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.088This paper presents a method of Online Classifying Based On Directed Graph(OCBDG), and designs a framework based on Web search engines in order to know about the content composition and evolvement of Web topics. It gets information about some topics from Web search engines, classifies the results into subtopics, and analyzes the relations between the subtopics and the evolvements of the subtopics. Experimental results prove that the framework can extract the subtopics in an about 70% precision and can show the evolvements of topics on Web in any time span truly and timely.
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Computer Engineering. 2009, 35(3): 260-262. https://doi.org/10.3969/j.issn.1000-3428.2009.03.089New generation of avionics system is highly integrated and modularized, highly safety operation system must be supported, and health monitor technology plays great part in the security and reliability of the system. This paper studies the health monitoring mechanism in an embedded Real Time Operation System(RTOS), and describes the critical part of the health monitor: error diagnosis, error injection, error response, error recovery.
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Computer Engineering. 2009, 35(3): 263-265,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.090For large and complex flow data such as ocean flow field, it is nearly impossible to visualize the whole information it contains. This paper introduces a topological simplification of 3D scalar fields for extracting water mass, and realizes the feature-based visualization. Based on the morse theory, this method constructs Morse-Smale complex over the important subregions to depart the water mass automatically, and repeatedly removes a pair of critical points from the complex to realize the combination of the initial water massm. The experiment verifies the feasibility and efficiency of the method.
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Computer Engineering. 2009, 35(3): 266-267,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.091Air quality information-sampling system is an important part in the whole air cleaner system. This paper introduces an air quality information-sampling system which has been designed and made out. As the complexity and randomicity of the air, this paper raises another new system on the base of the former system. This new system includes the LMS adapter filter subsystem which can make good performers in stochastic environment. It makes the new system more steady, predictable and intelligent.
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Computer Engineering. 2009, 35(3): 268-270. https://doi.org/10.3969/j.issn.1000-3428.2009.03.092According to the integrated technology of NetSolve and Web services, this paper gives services-oriented computing grid middleware architecture, and embeds the 3-layers function architecture of computing grid middleware in it. WebSolve system based on Web services is implemented with Java. performance evaluation with parallel Precondition Conjugate Gradients(PCG) is made to solve equations set several times, whose stepped-up is O(n).
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Computer Engineering. 2009, 35(3): 271-273. https://doi.org/10.3969/j.issn.1000-3428.2009.03.093This paper proposes a hybrid MPI+OpenMP parallel programming model suited for SMP cluster, which is close to the architecture of SMP cluster and combines two advantages of message passing and shared memory. It has better performance, on basis of which, the implementation mechanism of this hybrid model and the character of MPI message passing model are discussed. Experimental results show this hybrid parallel programming model is the best choice for SMP cluster under some conditions.
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Computer Engineering. 2009, 35(3): 274-276. https://doi.org/10.3969/j.issn.1000-3428.2009.03.094To solve the problems of Virtual Maintenance Training System(VMTS) of missile equipment such as simple function, equipment specified, lower developing efficiency and weak compatibility, etc. The research on general platform for VMTS of missile equipment is developed, which is based on the reuse of the resource and the compatibility of the system. Four key technologies about the general platform are studied. Four kinds of module which are scene simulation, modeling and manage of fault mechanism, Human-Computer Interaction(HCI) and control of maintenance task and two modes of virtual maintenance training are expounded. The structure of the general platform and the model system of the VMTS are introduced.
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Computer Engineering. 2009, 35(3): 277-278,. https://doi.org/10.3969/j.issn.1000-3428.2009.03.095In tourism information site, using virtual reality technology to display attractions is more lively and interesting than using words and pictures. There paper three major ways when using virtual reality technology to display scenes: simulation software in single computer, Web3D and panorama. This article brings a method that using Google Earth to display the scene online. It combines the advantages, abandon shortcomings which are in the three aforementioned ways. It can load large scene while connecting Internet, and cooperate with panorama. The method use Servlet to return dynamic KML, which let Google Earth start and display scenes. KML can be use to control the display of place mark, graphic notes and loading of 3D models. Place mark can be linked to panorama Web page or Servlet which will return 3D model via hyperlinks in the place mark notes.
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Computer Engineering. 2009, 35(3): 279-281. https://doi.org/10.3969/j.issn.1000-3428.2009.03.096Tag anti-collision is a significant issue in Radio Frequency Identification(RFID) system design, which determines the identification speed. Thus a novel anti-collision algorithm based on binary tree searching algorithms and BIBD(4,2,1) is proposed to solve this problem. Tag is divided into several sections, which only contain special sequences. Reader can efficiently get every UID by identifying sections one by one. Mathematics analysis and simulation results show that the algorithm presented improves the identification speed and outperforms the existing ones. It especially fits the identification conditions which contain more tags or tags with long UID.
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Computer Engineering. 2009, 35(3): 282-封三. https://doi.org/10.3969/j.issn.1000-3428.2009.03.097Applications of virtual reality requires graphic system to have the capacity of rendering more and more complex scenes in real time. It is natural to apply parallel rendering system based on PC cluster to virtual reality because of its high performance-cost ratio and good scalability. A sort-first parallel rendering system based on retained-mode is presented to study the key factors of parallel rendering efficiency. Implementation steps and experimental data are provided. The system is proved effective in parallel computing and load-balance problem, and capacity of rendering complex scene in real time can be achieved eventually.
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