20 August 2007, Volume 33 Issue 16
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Computer Engineering. 2007, 33(16): 1-3. https://doi.org/10.3969/j.issn.1000-3428.2007.16.001This paper develops a structure for schema merging that consists of schema mapping, key-foreignkey merging and user-defined integrity merging. Schema mapping transforms relational schema or other schema into deputy schema class. The paper suggests a new algorithm for key-foreignkey merging that makes use of deputy mechanism, proposes a new operator merge for user-defined integrity in which object deputy model makes schema transformation easier. And it implements the schema merging system based on object deputy model in Smalltalk environment, with some application examples.
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Computer Engineering. 2007, 33(16): 4-6. https://doi.org/10.3969/j.issn.1000-3428.2007.16.002This paper presents a new object verification framework to choose the correct building hypothesis in natural images. Compared to conventional approaches that extract the single feature, and assume little knowledge, the proposed approach extracts edge features and line-segment features, and turned object verification into a conditional probability when conditioned upon an object hypothesis. Based on the Bayesian theory, the prior knowledge can be converted into a series of prior probabilities to compute the maximum a posteriori estimate, so a new approach to object verification is presented. Experiments on the natural image sets demonstrate that the proposed approach can yield substantial improvements over the traditional approach on the performance of recognition.
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Computer Engineering. 2007, 33(16): 7-10. https://doi.org/10.3969/j.issn.1000-3428.2007.16.003A new real-time shot cut detection algorithm using edge feature is presented. To avoid high computation complexity in traditional feature-based detection algorithms, a fast edge pattern classification scheme working with only partially decoded video information is exploited to extract edge features. Instead of trying to find real edges in a frame, all intensity variations are considered and the ambiguity between them is reduced through separating the edges into eight sets according to their directions and normal directions, so the computation is very fast compared to existing feature-based algorithms. The frame similarity is measured by evaluating the similarity of edge distributions aming consecutive frames. The edge-based measure is combined with color histogram based similarity measure to improve the robustness. An algorithm for detecting shot cuts using an improved sliding window thresholding technique is designed and evaluated. Experimental results show that the algorithm is of high performance and applicable to real-time applications.
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Computer Engineering. 2007, 33(16): 11-13，1. https://doi.org/10.3969/j.issn.1000-3428.2007.16.004In some civilian applications of wireless sensor networks, the sensing nodes is so far away from base station that relaying nodes must be employed to forward data. Some relaying nodes use up their power early because they have heavier traffic load, which affects the network lifetime. This paper proposes the multi-phase placement strategy of relaying nodes, which implements an even energy consumption distribution among different nodes. Sensing nodes and relaying nodes consume the same power in every round of data transmission by adjusting location and data volume. Based on the strategy, this paper finds numerical relationship between the number of relaying nodes and network lifetime, offers a reference for the trade-off between increasing network lifetime and decreasing the number of relaying nodes.
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Computer Engineering. 2007, 33(16): 14-16. https://doi.org/10.3969/j.issn.1000-3428.2007.16.005In respect of the ellipse-like outline of the left ventricle, a new model for segmenting cardiac MRI image is presented, which is based on ellipse shape restriction level set model. Ellipse shape restriction is adopted based on Chan and Vese model to control evolvement of curve. The evolvement curve of level set is regarded as the new forecast of contour location, ellipse restriction is introduced to modify the forecast result. Accordingly, the results of the forecast and modification are taken respectively as new curve of the level set and shape information, till curve ceases evolvement. The results of the experiments prove its effectiveness for segmenting tagged cardiac MRI images.
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Computer Engineering. 2007, 33(16): 17-19，2. https://doi.org/10.3969/j.issn.1000-3428.2007.16.006On the basis of reviewing current researches on software architecture supporting for software development and analyzing their inadequacies, this paper advances a new refinement-based software architecture design method(ARSADM). The method combining architectural hiberarchy with views applies the software refinement technica in the process of software architecture design in order to guide the correct software architecture design.
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Computer Engineering. 2007, 33(16): 20-22. https://doi.org/10.3969/j.issn.1000-3428.2007.16.007The paper introduces a new fault-tolerant Clos network. By adding extra switches in each stage of it, the Clos network can maintain its performance and provide reliable services under few faults. The paper also presents a fault-tolerant routing algorithm for fault-tolerant Clos network. This algorithm uses a minimum distribution priority scheme handling Clos specification matrix column by column and completely achieves rearrangeable non-blocking routing. The fault-tolerant routing algorithm can reach a low time complexity O(N3/2) even in the worst case. The design of fault-tolerant Clos network and its algorithm is readily applicable to more reliable Clos network.
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Computer Engineering. 2007, 33(16): 23-25. https://doi.org/10.3969/j.issn.1000-3428.2007.16.008This paper proposes a feature extraction and recognition method of human face based on wavelet-moment descriptors and 2-dimensional principal component analysis(2DPCA). With this method, the matrix of wavelet-moment descriptors which describes the human face image’s essential feature is extracted, the matrix is projected and compressed with 2DPCA and the ultimate discriminant features is obtained. The features are classified with the nearest neighbor classifier. Experimental results on NUST603 face database confirm the efficiency of this method.
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Computer Engineering. 2007, 33(16): 26-28. https://doi.org/10.3969/j.issn.1000-3428.2007.16.009
Business component design is one of the hottest research issues in the development of enterprise information system. A business model description method is given, which uses business function view, business entity view, business organization view, business control view. Based on the semantic analysis of business model, relationship formulas between sampling points and relationship formulas between clusters are given. And the cluster algorithm is introduced to make the business component partitioning process more effectively. Cluster process diagram is brought out to identify the best component design result. The key steps of business component interface design are given as well. All of these provide feasible reference standards for component partitioning and interface design, and greatly enhance the quality of component design.
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Computer Engineering. 2007, 33(16): 29-31，3. https://doi.org/10.3969/j.issn.1000-3428.2007.16.010This paper presents the design of a highly re-configurable 64-bit adder, which is well suitable for VLIW digital signal processor. The adder can add two 64-bit operands, four 32-bit operands, eight 16-bit operands, or sixteen 8-bit operands. It is the hybrid of binary carry look-ahead adder of Brent-Kung, and the carry select adder. By using this approach, the area and wiring of the adder is reduced by 50%, keeping the delay proportional to Olog n. Simulation results indicate that, typical conditions in standard cell using 0.18μm technology, the proposed adder can complete 64-bit addition in 0.83 ns and dissipates only 0.315mW with the area of 0.149mm2.
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Computer Engineering. 2007, 33(16): 32-34. https://doi.org/10.3969/j.issn.1000-3428.2007.16.011In order to advance development efficiency, team members need to share their knowledge about the project on which they work. Aiming at the characteristics of the development of team project under Internet, this paper puts forward a team knowledge-sharing model and organizes the knowledge by using ontology. Based on the model, it defines the formalized method and rule as to subscribing and publishing knowledge. Through the experimental result, the method in the model enables team member to conveniently share knowledge with each other.
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Computer Engineering. 2007, 33(16): 35-37. https://doi.org/10.3969/j.issn.1000-3428.2007.16.012Aiming at problems of image transform in image enhancement and image restoration, this paper presents the design and implementation of a software tool for modifying huge remote sensing image frequency information. With the tool, frequency information as well as visualize frequency information are edited. Such standard filters as Barlett low-pass filter and Gaussian high-pass filter are supplied. The tool’s usefulness by designing a filter for periodic noise removal is demonstrated. The experiment with TM images shows the tool is efficient.
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Computer Engineering. 2007, 33(16): 38-40. https://doi.org/10.3969/j.issn.1000-3428.2007.16.013A perfect safety monitoring is helpful to maintaining stability of community. This paper focuses on the active fuzzy image database system for safety monitoring. An active fuzzy data model is put forward, which is suitable for safety monitor image database. A system structure of active fuzzy image database for safety monitoring is constructed, and the retrieval methods available for the system are discussed, the development direction of a new database system is pointed out.
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Computer Engineering. 2007, 33(16): 41-43. https://doi.org/10.3969/j.issn.1000-3428.2007.16.014In order to translate XML queries to SQL queries, this paper proposes a translation framework and algorithm from XSLT queries to SQL queries. It studies how to map DTD to relation schema and its reverse. The key is the process and algorithm of translating XSLT queries to SQL queries which is based on XML DTD and without any intermediate language. The algorithm extracts statement set from XSLT program, and then merges and simplifies XPath in statement. After splitting XPath, each part of SQL statement is extracted. And the algorithm has high generality.
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Computer Engineering. 2007, 33(16): 44-46,4. https://doi.org/10.3969/j.issn.1000-3428.2007.16.015This paper presents a fuzzy theory based risk calculation approach for information system security assessment. The approach assigns weights to risk factors through AHP and the fuzzy synthetic assessment model based on the risk calculation function factor analysis. It describes the method, the process and a typical instance of the risk calculation.
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Computer Engineering. 2007, 33(16): 47-49. https://doi.org/10.3969/j.issn.1000-3428.2007.16.016Combined with the mobile database system SwiftDB developed in the Laboratory of Database and Information System of Southeast University, the implementation method of embedded GIS is brought forward. Because the computing and storage capacity of embedded equipment are both less than PC, a data structure of vector and grid combination are presented. Based on this structure, an idea of dynamic block division is designed. The data structure has been applied in the example of shortest path query. Due to low bandwidth, high delay and easy to interrupt in the mobile environment, this system designs different methods for updating the map data based on the data volume. These methods benefit the consistency of data and the performance of the whole system.
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Computer Engineering. 2007, 33(16): 50-52,5. https://doi.org/10.3969/j.issn.1000-3428.2007.16.017Because microarray dataset contains a large number of columns and a small number of rows, mining the complete set of frequent closed patterns in microarray poses a great challenge for traditional frequent closed patterns mining algorithms which are based on column-enumerate. CARPENTER, based on row-enumerate, has addressed this problem. However, CARPENTER is inefficient by using the transposed table (TT) to mine the complete set of frequent closed patterns in microarray. A new algorithm, MFCPLG, is proposed inspired by CARPENTER, and a LG-tree structure is suggested. Several experiments are performed on real-life microarray data to show that the MFCPLG algorithm is faster than the CARPENTER algorithm.
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Computer Engineering. 2007, 33(16): 53-55. https://doi.org/10.3969/j.issn.1000-3428.2007.16.018OSEK/VDX is a software standard with an open-ended architecture for distributed control units in vehicles. The structure of AutoOSEK which is an realization of embedded real-time operating system(RTOS) based on OSEK/VDX standard is introduced. The method of separated codes related with processor is adopted by AutoOSEK for satisfying reliability, both of the idea of realization of part irrelated with processor and part related with processor are discussed, and the performance of AutoOSEK is analyzed. AutoOSEK is realized on the chip of Motorola HCS12 and multi-hardware platform based on ARM kernel, and applied well to the automotive electronic control system.
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Computer Engineering. 2007, 33(16): 56-58. https://doi.org/10.3969/j.issn.1000-3428.2007.16.019This paper focuses on the problem of inserting constrained edge into D-triangulation. It is a very effective method of changing D-triangulation into CD-triangulation that constrained edge is inserted into D-triangulation, and only CD-triangulation can present real terrain and relief. It introduces some basic conceptions about the algorithm of inserting constrained edge, analyses present algorithms’ characteristics and presents a better algorithm of inserting constrained edge——“inserting-swapping” algorithm. The algorithm can effectively deal with all kinds of instances, and can be implemented by programs easily, and can accord with requirements of the project.
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Computer Engineering. 2007, 33(16): 59-61,6. https://doi.org/10.3969/j.issn.1000-3428.2007.16.020This paper presents a new dynamic service queue management model for the multi-level data exchange platform of civil aviation. It introduces multithread modes when implementing the model, and discusses the update time of the request priorities and the load related parameters setting. In this model, service requests with dynamic priorities are sorted through three-class multi-heap multithreads, consequently the model conducted the orderly service functions according to the priority of request. Experimental results show that the model is adequate to the sophisticated multi-user data exchange and sharing platform of civil aviation.
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Computer Engineering. 2007, 33(16): 62-64. https://doi.org/10.3969/j.issn.1000-3428.2007.16.021A new method of triangulation for large scale scattered 3D points is proposed. This method is based on the available CAD model, with the thought of DC (divide and conquer). Alignment between the data and the CAD model, registration which establishes correspondence between the data points and those on the CAD trimmed NURBS surface entities; 2D Delaunay triangulation, performed on the corresponding points in the parametric domains(u,v) of each entity, application of the connectivity structure to the 3D data points for each mesh patch; Elimination of redundant triangles of each 3D mesh patch and stitching of patches together. Unlike many other methods, it is not constrained by certain types of measurement distribution or object shape. The experimental results testify that the approach is feasible and efficient.
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Computer Engineering. 2007, 33(16): 65-67，7. https://doi.org/10.3969/j.issn.1000-3428.2007.16.022oftware process technology provides developers a standard software development norm. which greatly enhances the productivity of software development. Among most process technologies, CMMI, released by SEI, is widely accepted. This paper expatiates the shortages of CMMI. Against these shortages, a measurement model PSM4CMMI is proposed on the base of the definition of CMMI and PSM. It analyzes the effects of all the modules, introduces how to implement the SPMAS system using the model.
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Computer Engineering. 2007, 33(16): 68-70. https://doi.org/10.3969/j.issn.1000-3428.2007.16.023The powerful data management function of data grid allows us to integrate distributed and complex remote sensing data, and provides a consistent grid environment for storing and retrieving remote sensing data. The research on grid middleware of remote sensing data access and integration attempts to provide standard interfaces to access distributed and heterogeneous remote sensing data, and to make the isolated remote sensing data be shared between each other. This paper designes and implementes grid services of remote sensing data access and integration via OGSA-DAI, builds a high performance grid system to share remote sensing data. It analyzes key technologies in the system and describes a practical application of the system.
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Computer Engineering. 2007, 33(16): 71-73，7. https://doi.org/10.3969/j.issn.1000-3428.2007.16.024VoiceXML is designed for voice browsers, so it has no multi-party communication control functions. By analyzing the main functions needed by the multi-party communication service, the object extended mechanism of VoiceXML is used to implement the multi-party communication control function. It proposes two multi-party communication control function extended schemes, one is block mode and the other is non-block mode to join conference operator. The two schema are compared which shows the two schema can be provided for VoiceXML programmer at the same time.
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Computer Engineering. 2007, 33(16): 74-76. https://doi.org/10.3969/j.issn.1000-3428.2007.16.025
This paper discusses the information service grid and presents a framework model of the consolidate network computing and assistant aptitude information flat provided by user and makes use of existing basic network establishment, protocol criterion, Web and database technology. The object is that it is produced by the new great information flat and basic software establishment for grid compute trussed on the OS and Web by the basis of Internet. The systematic model is described, which makes the information service work most efficiently and takes full use of the hardware resources.
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Computer Engineering. 2007, 33(16): 77-79,8. https://doi.org/10.3969/j.issn.1000-3428.2007.16.026This paper explores a load-balance algorithm for a cluster file system which contains two levels of metadata-server. The primary-level-server quickly distributes tasks to second-level-server depending on the closest load-balance information. A method which accurately reflects I/O traffic and storage of storage-node: computes the heat-value of file, on which a more logical storage allocation is realized. Experimental results show that the algorithm shortens the executing time of tasks and improves the system performance compared with other load algorithms.
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Computer Engineering. 2007, 33(16): 80-82. https://doi.org/10.3969/j.issn.1000-3428.2007.16.027This paper presents a new Clos network routing algorithm named MDP(minimum distribution priority) algorithm in order to reduce the high time complexity of original algorithm for Clos network. It illustrates that it is an independent problem whether a column in specification matrix is complete. As a result, it introduces a minimum distribution priority scheme handling Clos specification matrix column by column and eliminates backtracking among columns and backtracking among elements in the same column. The MDP algorithm ensures that non-blocking routing can be completely achieved and a low time complexity O(N3/2) can still be reached in the worst case. So the algorithm is readily applicable to the control of Clos network.
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Computer Engineering. 2007, 33(16): 83-85. https://doi.org/10.3969/j.issn.1000-3428.2007.16.028The multicast is one of key technologies for MANET applications and multicast routing protocols have been the focus of this research area. However, related researches have proved that traditional layered methods are inefficient in improving the performance in MANET. This paper presents a joint routing metric which is based on traffic prediction in a flow and the related essential information of physical layer, MAC layer, link layer, and network layer. Based on ODMRP and cross-layer design approach, a joint multicast routing protocol scheme introduced, which not only guarantees the independence of each layer of networks but also facilitates the exchange of information among network layers while avoiding the design complexity of cross-layer design approach. The simulation results show that the integrated performance of joint multicast routing protocol is better than that of ODMRP.
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Computer Engineering. 2007, 33(16): 86-87,9. https://doi.org/10.3969/j.issn.1000-3428.2007.16.029P2P technology presents a suitable solution to the scalability problem of massively multiplayer online games. But for the heterogeneous of computational capacity and bandwidth among nodes, the system should have load-balancing ability to transfer the load from heavy-loaded nodes to light-loaded nodes dynamically with little ratio of load-transfer. This paper proposes a coordinator-based dynamic load-balancing algorithm during the game. According to the experiments’ results, the algorithms can efficiently balance load distribution and decrease the ratio of load-transfer.
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Computer Engineering. 2007, 33(16): 88-91. https://doi.org/10.3969/j.issn.1000-3428.2007.16.030The grid is a highly heterogeneous environment that can potentially provide seamless, fast and efficient access to range of resources that are distributed over a wide area. The major characteristics are stochastic and dynamic. It is a difficulty for the development of grid application. This paper analyses the stochastic feature of grid and catalog grid resources. Trust is integrated into the resource schedule, and the multi-agent-based high- available schedule model for providing the steady credible QoS is presented.
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Computer Engineering. 2007, 33(16): 92-94. https://doi.org/10.3969/j.issn.1000-3428.2007.16.031A mobile IPv6 testbed based on Linux is set up and a series of experimental studies on the MAC and IP layer handoff are performed. According to the experimental result with statistic analysis, the distribution of mobile IPv6 latency is presented. Factors which affect the handoff efficiency are investigated such as the ESSID and channel of wireless network. Approaches to improving the handoff efficiency are proposed.
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Computer Engineering. 2007, 33(16): 95-97. https://doi.org/10.3969/j.issn.1000-3428.2007.16.032A remote mobile terminal management system is presented on the basis of OMA device management enabler. The system leverages a distributed architecture to organize functional modules. The system specifies a uniform message frame for module communications and processes XML/WBXML tags of the management package by a finite state machine. It designs the work flow for firmware upgrade package management covering generation and putting in storage, which undertakes life-cycle management concept, and defines layered Web Services interfaces and appropriate Web Services publishing mechanisms based on the specific scenarios.
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Computer Engineering. 2007, 33(16): 98-100,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.033The difference of the bandwidth between the lines up and down can’t satisfy an P2P network according to the request for data distribution in the realistic network environment in which the ADSL is the main connecting manner. This results in the service supplier’s increasing the document servers so that they can make up the translation delay of the documents that produced by the shortage of the down-line bandwidth. Through improvement of the distribute algorithm of the existing documents, the speed of the document distribution in the P2P network can be accelerated without the increase of the document server. Improving the algorithm of the document distribution in the eMule protocol, it can speed up the document distribution by raising the quantity of copy in the unit time.
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Computer Engineering. 2007, 33(16): 101-103. https://doi.org/10.3969/j.issn.1000-3428.2007.16.034The article describes the realization of a simple networks media content service archetype based on mobile agent active networks, and discusses the key technique to realize this archetype according to the specific application in application layer active networks environment and analysis on running procedure of static proxy and active proxy. Aiming at the characteristic of the proxy, it tests and appraises services customization and efficiency of the active messages, illuminates that proxy outperforms traditional server model in service customization and the usability of proxy mobile.
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Computer Engineering. 2007, 33(16): 104-105，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.035This paper proposes a new structure and generation method of worm active countering code. It analyses structure and drawback of existing ones, proposes a new structure and generation method of worm countering code, and does experiment with Blaster, Nachi and Sasser worms. It shows that this structure can reduce distribution time and can be used by anti-worm and worm vaccination.
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Computer Engineering. 2007, 33(16): 106-108. https://doi.org/10.3969/j.issn.1000-3428.2007.16.036This paper presents a new self-embedding watermark scheme for image authentication, which extracts image features from the U component of the SVD domain to generate watermark and embeds watermark in the D component of the SVD domain. In the new scheme, the watermark generating and watermark embedding are disposed in the image itself, and the received image authentication needs no information about the original image or watermark. The scheme increases watermark security and prevents forged watermark. Experimental results show that the algorithm can identify intentional content modification and common image processing, and also indicate the location where a modification takes place.
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Computer Engineering. 2007, 33(16): 109-110，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.037This paper develops a technique by introducing probabilistic polynomial-time processes for analyzing security protocols, because of the limitations of the Spi calculus. The technique is an improvement of the Spi calculus. Protocol adversaries may be any probabilistic polynomial-time processes in the technique, and security may be expressed in terms of observational equivalence. By analyzing a protocol based on ElGamal encryption and Diffie-Hellman key exchange, it demonstrates the analysis capability of the technique for protocol security.
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Computer Engineering. 2007, 33(16): 111-113. https://doi.org/10.3969/j.issn.1000-3428.2007.16.038In computer communication networks, traffic series contain statistical patterns that are useful for eavesdropper to collect information for launching traffic analysis attacks. This paper presents a system scheme and a prototype to prevent traffic analysis in IP-based Ethernet based on link padding methodology. The prototype is built on a Linux machine by using three C language libraries, namely, Libnet, Libpcap and OpenSSL.
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Computer Engineering. 2007, 33(16): 114-116. https://doi.org/10.3969/j.issn.1000-3428.2007.16.039This article introduces the progress and characteristics of BIOS security threat, summarizes the BIOS security risk classification, advances a model of BIOS security threat and a model of BIOS security detection which based on scanning of BIOS vulnerabilities and measuring of BIOS code integrity. A BIOS security detection system, based on the libraries of BIOS vulnerabilities and BIOS standard code samples, is implemented. Further study directions about enhancing and extending BIOS security role in information security fundamental solution are also presented.
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Computer Engineering. 2007, 33(16): 117-119，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.040A novel computer forensics system based on remote control technology is present. By using three different ways of evidence-obtaining and evidence-controlling for different subjects, the system can realize objective of dynamic obtaining electronic evidence of the monitored subjects, including the research on the key technologies of process hiding and file hiding, register modifying and hiding, ports back-bouncing, and data encrypting about the system as well. Experimental result shows that the system realizes the active obtaining evidence to the monitored subjects on the network by different applications, and it demonstrates that this is a new technical thinking in the current computer forensics technology.
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Computer Engineering. 2007, 33(16): 120-122. https://doi.org/10.3969/j.issn.1000-3428.2007.16.041Based on common criteria, a three-phased requirement engineering method is presented. It focuses the early-phased security requirements engineering, and proposes an extended i* framework by defining new nodes and links. The extended model can model the relationships of security environments and security objectives precisely and visually, thus help to define the required security objectives. Taking the requirement development of an industrial data acquisition system as an example, the modeling processes based on the proposed model is discussed.
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Computer Engineering. 2007, 33(16): 123-125. https://doi.org/10.3969/j.issn.1000-3428.2007.16.042An improved dynamic group key management scheme for multicast based on LKH tree is proposed. The node coordinates are used to mark key tree in this scheme, which facilitates rekeying. Group manager computes the keys on path of the user node location according to the user ID and it just needs to maintain its private key. This scheme is suitable for the large-scale group. The security, group manager computation amount, key distribution amount and others performances of the scheme are analyzed. Compared with the traditional LKH scheme and other improved schemes, it reduces the number of keys for key management and the computation and communication amount when re-keying, which is suitable for large-scale group.
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Computer Engineering. 2007, 33(16): 126-127. https://doi.org/10.3969/j.issn.1000-3428.2007.16.043With the help of a secure and efficient group blind signature, a new E-cash system with multi-bank is designed. The electronic cash satisfies divisibility and anonymity-revocability in this system; on the other hand, it makes use of partially blind signature, which mitigates the complexity of key management for bank and promote depositing efficiency.
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Computer Engineering. 2007, 33(16): 128-129，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.044This paper analyses the technologies of event management system based on log and gives out the realization frame. It focuses on analyzing association rules of log disposition. And according to the characteristics of log, it optimizes log data mining algorithm——Apriori algorithm with the technology of data mining, which improves the interaction, security and real-time responsibility of the system. It also probes into the event interaction based on the result of handling log.
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Computer Engineering. 2007, 33(16): 130-132. https://doi.org/10.3969/j.issn.1000-3428.2007.16.045The paper discusses the application requirements and basic design principles for the existing IP multicast source authentication schemes. Several typical authentication schemes are briefly analyzed. Qualitative analyses of these schemes show the overall performance characteristics and quantitative analyses present the overhead of these schemes. When designing practical IP multicast source authentication schemes, qualitative and quantitative analyses can help to choose the scheme which best meets the application requirements.
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Computer Engineering. 2007, 33(16): 133-135，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.046Network security evaluation technologies and methods are important to the network security protection system. Combined with the actual experience and research results and based on the analysis of the present status about security evaluation technologies, this paper puts forward and describes an efficient model and algorithm with qualitative analysis and the quantify calculate, and gives a risk evaluation flow based on the algorithm. The model is applied in security evaluation work and the practice result proves that the model and algorithm do a good directive function in network security protection and management.
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Computer Engineering. 2007, 33(16): 136-138. https://doi.org/10.3969/j.issn.1000-3428.2007.16.047It is difficult to perform unified description policy on different secure devices in policy management research. This paper adds extensible accidence database and syntax database in the PDP, and policy transformation is performed through universal agent program in the PEP, which supports the extension of different devices and types in the system. A new method of policy transformation for different types of secure devices is put forward, which improves the expandability and universality of the policy management.
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Computer Engineering. 2007, 33(16): 139-141. https://doi.org/10.3969/j.issn.1000-3428.2007.16.048On the basis of analyzing the features of distributed denial of service (DDoS) attacks, flow connection entropy time series analysis is proposed. It uses non-parametric CUSUM algorithm to complete the detection task of DDoS attacks. It minimizes the average delay of detection for a given false alarm rate. It has better detection effect on the fixed source IP and random destination ports’s DDoS. Experimental result demonstrates this model can detect DDoS attack as early as possible with high detection accuracy.
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Computer Engineering. 2007, 33(16): 142-143，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.049Buffer overflow attack is one of the most threatening attack types and it jeopardizes information security a lot. According to the principle of the attack, this paper generalizes three necessary steps of a buffer overflow attack. It divides the most popular technologies of buffer overflow attack detection into three types in light of detecting the three attack steps, and also analyzes and studies those technologies.
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Computer Engineering. 2007, 33(16): 144-146，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.050According to the idea of canonical correlation analysis (CCA) and degree of membership, a new method of image feature extraction and recognition is proposed based on fuzzy canonical correlation analysis. An appropriate membership function is defined to express the distribution of image samples. CCA is applied to extract features from multiple information sources, which combine the information about gray level and the distribution of samples together. In addition, Fisher linear discriminant analysis is an extreme situation of the new method. The results of experiments on ORL face databases show that the features have the powerful ability of recognition, and that the presented method is efficient.
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Computer Engineering. 2007, 33(16): 147-149. https://doi.org/10.3969/j.issn.1000-3428.2007.16.051Systems based on correlation-tracking can track objects based on 2-dimensional shape, however traditional correlation-tracking methods have difficulty in detecting an object when the object is transformed or partially obscured by clutter. This paper describes one of the main problems of image-based correlation tracking systems, and proposes a new solution of using modified MCD correlation matching and adaptive modal modification based on multiple frame cumulation. The system is tested on both real and simulated imagery which is found to be robust in the presence of obscuring clutter and transforming and be practical.
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Computer Engineering. 2007, 33(16): 150-152. https://doi.org/10.3969/j.issn.1000-3428.2007.16.052Feature selection is frequently used as a preprocessing step to text classification, which is effective in reducing dimensionality and increasing classification accuracy. However, most feature selection algorithms fail to take advantage of the co-occurrence of words. This paper explores the use of association features to enhance the performance of primitive features and proposes a new fast algorithm for identifying relevant features as well as redundancy among high dimensional features. The experiment are conducted with Naïve Bayes, it compares the method with other feature selection algorithms with respect to the feature numbers, accuracy and effectiveness.
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Computer Engineering. 2007, 33(16): 153-155，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.053A new Bayesian optimization algorithm is presented by incorporating mutation operator into Bayesian optimization algorithm. A diversity function of population is proposed and the mutation operator is incorporated in BOA through this function. The original objective is to maintain the diversity of population using the neighborhood search of mutation operator. It is expected that the proposed algorithm can get genuine global information by combining the global information in current population extracted by Bayesian probability model and local information explored by mutation operator. Experimental results show that the proposed algorithm outperforms BOA.
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Computer Engineering. 2007, 33(16): 156-158. https://doi.org/10.3969/j.issn.1000-3428.2007.16.054The study and implementation of biased summarization system is the basis of intelligent information service. The biased summarization can process the single document summarization and multi-document summarizations, so it is considered as a useful tool to meet users’ demands. The summarization approach is presented which is based on the density distribution of keywords. The conceptual expansion is applied to get more synonymies. The strategy of extracting sentences is discussed based on the density distribution of keywords. The summarization approach shows its high efficiency and high precision under the two evaluations, one is based on information retrieval(IR) and another is based on question & answering(QA).
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Computer Engineering. 2007, 33(16): 159-161. https://doi.org/10.3969/j.issn.1000-3428.2007.16.055This paper presents the concept of semantic pattern, and constructs semantic pattern base of English preposition phrases and sentences, major parameter base and knowledge base of English set phrases. Based on the characteristics of the semantic patterns of English prepositions, a new semantic analysis and Chinese translation algorithm based on semantic pattern decomposition is presented, which combines with sentence semantic pattern base and set phrases knowledge base to resolve the problem. Test results show that this method has a good effect on resolving Chinese translation of English prepositions.
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Computer Engineering. 2007, 33(16): 162-163. https://doi.org/10.3969/j.issn.1000-3428.2007.16.056The laser stripe image gathered in the structured light measurement system is needed to be processed effectively. A threshold segmentation method based on the difference image is put forward, which is used to segment the laser stripe image and a two-value image is obtained, then neural network is applied to process the two-value laser stripe image to get the thinning stripe. The processed thinning stripe satisfies the requirement that the precision is 0.05%, the two-value processing time is no more than one second and that of the thinning is less than two seconds. The time increased compared to traditional methods and the result has already been applied to the pre-processing of feature parameter matching in the object 3D reconstruction successfully.
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Computer Engineering. 2007, 33(16): 164-165. https://doi.org/10.3969/j.issn.1000-3428.2007.16.057News special topic in Web site has plentiful pages. People can get main information rapidly by automatic multidocument summarization. A method which uses time stamp to improve sentence extraction quality is presented. The method of news sentence extraction, sentence importance calculation, and redundancy reducing is introduced. Experimental results show that summarization is good enough for practical application.
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Computer Engineering. 2007, 33(16): 166-167，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.058Hough transform is an effective approach for curve detection. Due to the large computational complexity of ellipse detection using traditional Hough transform, the article presents a method based on Hough transform to decide whether the input figure is an ellipse. The method utilizes a geometric attribute of ellipse, and reduces the statistical dimension of Hough parameter space. As a result, computational complexity decreases and ellipse contour is detected quickly.
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Computer Engineering. 2007, 33(16): 168-171. https://doi.org/10.3969/j.issn.1000-3428.2007.16.059
By analyzing the basic principles of artificial immune network, accuracy and high performance of fuzzy computation for information intelligent processing, an intelligent algorithm of fuzzy dynamic clustering based on immune network is proposed. By importing the principles of auto-justifying threshold and auto-evolution, the effect of man-made outer parameters is avoided, and while the results are automatically asserted on charge of the required clustering number, the reasons are recorded, by which the practicability and replant ion of the algorithm are both enhanced. Application results of cooperation credit rating show the searching of clustering is rational and feasible, while the developing trend and the reference of decision-making are also intelligently provided through the procedures of evolution.
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Computer Engineering. 2007, 33(16): 172-174. https://doi.org/10.3969/j.issn.1000-3428.2007.16.060In order to overcome the shortage of global motion compensation algorithm in video object segmentation, a new algorithm, which is based on local motion similarity is proposed. The motion vectors are processed by accumulation and median filter; the first segmentation of moving video object is executed according to local motion similarity and the spacial relativity is used for second segmentation; the edge of video moving object is made more exactly. Experimental results of different video sequence show the proposed algorithm has a better veracity of segmentation compared with other algorithms.
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Computer Engineering. 2007, 33(16): 175-177，. https://doi.org/10.3969/j.issn.1000-3428.2007.16.061Quantification obtained by quantifying the degree of similarity among synonyms by term similarity accurately, is used to improve the simple Bayesian network for information retrieval and for carrying out an effective probability inference. Experimental results show not only a good retrieval effectiveness of the new model, but a more reasonable ranking of relevant documents.
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Computer Engineering. 2007, 33(16): 178-180. https://doi.org/10.3969/j.issn.1000-3428.2007.16.062An algorithm based on color gradient for image features points match is proposed. Color gradient information and geometric characteristic of the features of both images are mixed into Laplacian matrixes. The matrixes are decomposed by the singular value decomposion(SVD), a relation matrix that denotes the match degree among feature points is constructed by the result of the decomposition. The match feature points of the two images are obtained according to the relation matrix. Experimental results indicate that the algorithm has the higher matching precision.
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Computer Engineering. 2007, 33(16): 181-182,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.063Based on GA frame and biological thery of DNA technology, DNA-GA utilizes double helix structure of DNA and utilizes molecular satisfying the waston-crick complementary condition to code and operate. DNA-GA inherits global search capability, enhances validity and speed of convergence, avoids prematurely and lower convergent speed of classic genetic algorithm. It is fit for solving the problem of shortest path planning on curved surface. Numerical simulation example shows its effectiveness and validity.
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Computer Engineering. 2007, 33(16): 183-185. https://doi.org/10.3969/j.issn.1000-3428.2007.16.064Gene expression data measured with microarray technology is useful in the classification of cancer. A rough sets based method for gene expression data classification is proposed and its validity is verified on acute leukemia classification. The result with high success rate indicates the rough sets approach is very promising and can hold a high potential to become a useful tool in bioinformatics.
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Computer Engineering. 2007, 33(16): 186-188. https://doi.org/10.3969/j.issn.1000-3428.2007.16.065Confines of declining angles and definition in the emendation as well as the affection of plate frame, rivet, and space mark to the extraction are the key problems to license plate recognition (LPR). An improved Harris corner detection algorithm utilizing maximums and template-match (HMT) is proposed. With the algorithm, the inner-corners can be extracted simply and exactly, not affected by the declining angles. On the basis of the inner-corers, the plate is emendated without frame and the characters are located at the center of the image. Thus the characters can be extracted accurately by considering them as a whole. The experimentol results show efficiency and good performance of the algorithm in emendation and extraction.
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Computer Engineering. 2007, 33(16): 189-190. https://doi.org/10.3969/j.issn.1000-3428.2007.16.066Traditionally, the algorithm of ID3 is a “greedy” algorithm which searches and compares the attribute of each level in the decision tree. Based on the unrelativity among different levels, this article brings out an improved algorithm called E-ID3. It use a method of “compute two steps and exectue one step”, which can give a good suggestion. Experimental results show it has better efficiency than ID3 when building up decision tree.
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Computer Engineering. 2007, 33(16): 191-192,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.067Based on the idea of sequential heuristic search, this paper proposes a new ant colony optimization algorithm for the classical graph coloring problem to effectively avoid the weakness of easily running into local minimum of heuristic research. Series of numerical simulations and experiments show the effectiveness and generality of the method.
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Computer Engineering. 2007, 33(16): 193-195. https://doi.org/10.3969/j.issn.1000-3428.2007.16.068The article proposes a Rough set concept of impartibility pattern of the properties and their relationships, which is based on the theory of properties reduction by use of the method of matrixs. The article presents a method of condition property and values of the property reduction. Experimental results show that the method is easier and quicker than the traditional one of rough set.
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Computer Engineering. 2007, 33(16): 196-198. https://doi.org/10.3969/j.issn.1000-3428.2007.16.069This paper introduces the research status of knowledge base and the meaning of using it in the design of expert referring system. It analyzes the design of knowledge map and knowledge engine when no expert is on duty and the implementation of the experts’ collaboration in real-time consultancy.
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Computer Engineering. 2007, 33(16): 199-201. https://doi.org/10.3969/j.issn.1000-3428.2007.16.070This paper puts forward a new kind of general packet radio service(GPRS) remote system for wireless autonomous rainfall monitoring. With advanced and reliable GPRS wireless communication and Internet technology, data service center(DSC) of the system is set up based on B/S framework. The functions, which are the remote management of rainfall stations and data query, are realized through database programming. And dynamic distributed maps of rainfall can be displayed in Web pages using one Website for rainfall information querying. The system is also a general ideal model for other data acquisition and processing systems.
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Computer Engineering. 2007, 33(16): 202-204. https://doi.org/10.3969/j.issn.1000-3428.2007.16.071Material decay monitoring, using techniques of video, computer image processing and pattern identification, detects, processes and manages the external material decay image. The color characteristic and space structure information of the external material decay image are analyzed. The statistics character of the material decay image is extracted by color histogram, color coherence vector, color correlogram and fractal dimension. The similarity of the material decay image is presented by Euclidean distance of the color character, on which the match and query system of material decay based on image retrieval technology is implemented.
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Computer Engineering. 2007, 33(16): 205-207. https://doi.org/10.3969/j.issn.1000-3428.2007.16.072
To solve problems of “offline-work” and “dispersed-deploy” in the self-help service system, the structure and strategies of smart client are investigated, and two universal application models of “occasional connect” and “intelligent update” are proposed for secondary development. The complete process of self-help service system is illustrated, including requirement analysis, project design and technical realization. Through the actual results of operations, smart client is manifested with outstanding advantage and favorable feasibility in improving work quality, integrating Web Services and reducing maintenance cost.
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Computer Engineering. 2007, 33(16): 208-210. https://doi.org/10.3969/j.issn.1000-3428.2007.16.073On the issue how to design the architecture of multi-core processor as to improve its performance, this paper researches on the multi-core processor architecture design referring to the theory of traditional multiprocessor, discloses the development trends of commercial multi-core processors by making a study of current commercial multi-core processors, and reflects on the future of multi-core processor design.
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Computer Engineering. 2007, 33(16): 211-213. https://doi.org/10.3969/j.issn.1000-3428.2007.16.074Modular multiplication of large integers is the kernel operation in many public-key crypto-systems. It is also the bottleneck of the computing efficiency. Based on Montgomery multiplication algorithm, this paper presents an improved multiplication algorithm and its exponentiation algorithm, which is twice faster than the conventional version, with about 50% reduction in iterations by using modified booth encoding. A novel architecture using carry save adders (CSA) tree is applied to the modular exponentiator, without computing full addition of the output of each modular multiplication. The result shows that the modular exponentiator is about 184Kb/s for 1 024-bit operands at a clock of 97MHz and well suitable for designing the high-speed public-key coprocessor.
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Computer Engineering. 2007, 33(16): 214-216. https://doi.org/10.3969/j.issn.1000-3428.2007.16.075This paper proposes a new class of variable-to-variable-length compression codes called as state’s reversal run length codes(SRRL). Lengths of runs of 0s and 1s are directly encoded to compress a precomputed test set without limitation on runs of 0s as proposed. At the same time, it rejects an additional bit necessary for both adjacent run sequences in alternation and run length codes(ARL). Its decompression architecture is a simple finite state machine(FSM)and doesn’t require a cyclical scan register (CSR), whose length is equal to the length of the scan chain. Experimental results show that SRRL codes can efficiently compress test data.
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Computer Engineering. 2007, 33(16): 217-219. https://doi.org/10.3969/j.issn.1000-3428.2007.16.076A self-adaptive signal timing optimization model is conducted for a single intersection. In the model, the traffic flux of the next cycle is forecast with one of the current cycle. The vehicle queue length of every phase when green ending is adopted as one of the multiple control objectives. All the objectives are integrated into a target in the way of ideal point. The genetic algorithm is adopted in the paper. The simulation computing data shows the algorithm is effective and speedy.
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Computer Engineering. 2007, 33(16): 220-222,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.077This paper proposes a simplified AES algorithm of resistant to zero value DPA (differential power analysis) attack and its VLSI implementation. In order to minimize the influence of the modification to the hardware, it makes some improvements to the additive masking AES algorithm and employs such methods as module reuse and altering calculation order to reduce chip area and maintain its speed. Using the HHNEC 0.25µm CMOS process, the scale of the design is about 43k equivalent gates and its system frequency will be up to 40MHz. The throughputs of the 128-bit dada encryption and decryption are as high as 470Mb/s.
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Computer Engineering. 2007, 33(16): 223-225,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.078To keep the relative operation precision and enhance real-time ability in control operations of assembler program, while the inputs were greatly changed in extent, a high precision real-time control iterated algorithm is introduced. The results of tests used for two-order filter and differential control unit based on dsPIC30F controller prove the algorithm’s effectiveness.
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Computer Engineering. 2007, 33(16): 226-227,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.079This paper analyses the problem of the quadratic phase for multiple frequency ranging based on chirp signal, and the method of the phase elimination is proposed. Ambiguity in ranging is resolved by the Chinese remainder theory. It is simple in algorithm, convenient to be realized and accurate. Simulation results indicate that this algorithm is accurate for ranging.
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Computer Engineering. 2007, 33(16): 228-230. https://doi.org/10.3969/j.issn.1000-3428.2007.16.080This paper discusses the application on compuation measurement of asymmetry with CT images in ear cholesteatoma diagnosis. A computer-aided diagnosis software system based on the asymmetry theory is developed in purpose of computing the measurement of asymmetry with CT images. It gains the asymmetry value of inputted image by searching its optimum symmetry with stepwise refinement, compares it with experiential thresholds and puts forward its judgement.
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Computer Engineering. 2007, 33(16): 231-233. https://doi.org/10.3969/j.issn.1000-3428.2007.16.081In order to provide a set of simple interfaces using the mobile location service capability to IT developers, this paper presents a Web Services-based mobile location access gateway by using for reference the design idea of Parlay X API, and designs the inner structure and the external interfaces of the access gateway, and implements a MLP-based mobile location access gateway. Test results show the gateway can work well and have good performance.
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Computer Engineering. 2007, 33(16): 234-236. https://doi.org/10.3969/j.issn.1000-3428.2007.16.082This paper discusses how to develop an Ethernet interface for a smart entry controller based on S3C44B0X CPU with ARM7TDMI core. The hardware interface circuit is designed with an Ethernet controller chip RTL8019AS as the circuit’s central component. The development and compiling process of the embedded application software are described. The server software running on uCLinux operating system and the client software running on Windows operating system are developed, and the two parties’ communication based on TCP/IP protocol are realized. The communication’s good performance has been proved by test, and the remote data transmission can be realized through the Ethernet.
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Computer Engineering. 2007, 33(16): 237-239. https://doi.org/10.3969/j.issn.1000-3428.2007.16.083The research on combat effectiveness of missile weapon system is foundational for evaluation of equipment ability, military tactics study of missile, and establishment of fire rule. A simulation-based missile weapon system efficiency evaluation software is introduced. Function of each module of the software is described. Practice shows that cumbersome and repetitive work of computation can be avoided by application of the software, and thus time and manpower are saved. The accuracy and the feasibility of the calculation result is guaranteed nicely.
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Computer Engineering. 2007, 33(16): 240-242,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.084To manually deploy and maintain an application system on many nodes in a cluster is a tedious job. Remote application deployment system, using a single console in management center, can automatically install operating system and install, upgrade or uninstall application software on any cluster node via wide area network. The system can install Linux operating system on lots of nodes quickly at the same time, supports installation of various Linux versions and has good scalability. It helps to reduce the management cost and improve the system availability significantly.
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Computer Engineering. 2007, 33(16): 243-245. https://doi.org/10.3969/j.issn.1000-3428.2007.16.085Based on research on the components and working process of embedded MMS client, this paper presents a method to generate a PDU rapidly by MMS datagram template, and provides a kind of useful model for building embedded MMS client. Equipped with different sensor, the MMS client can work in different fields, such as safety-guard, nursing, guard against theft on vehicle and logistics. With the protocol software, the MMS client can be supported by different servers.
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Computer Engineering. 2007, 33(16): 246-247,.Based on the analysis of a real-time embedded operating system μC/OS-II which is open source, some improvements about schedule mechanism are put forward to support more than 64 scheduling tasks. Divided into different groups, different schedule algorithms can be adopted according to the requirements of practical application. Implementation of the round-robin scheduling and priority schedule in local are put forward. Meanwhile, priority-based schedule algorithm is kept in the whole.
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Computer Engineering. 2007, 33(16): 248-250. https://doi.org/10.3969/j.issn.1000-3428.2007.16.087The touchscreen device and embedded desktop system based on graphic library have been widely used on embedded developing platform based on 32-bit CPU as the interface between people and machine. The process of designing and developing the embedded Linux desktop system on the Total5200 developing platform based on PowerPC architecture is introduced, including developing the Linux touchscreen device driver program and porting the Qtopia desktop system. The common problems in the process are analyzed. Means of realizing the embedded desktop system on JFFS2 file system are given.
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Computer Engineering. 2007, 33(16): 251-252,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.088This paper introduces a new LUT based on multiplication to realize the color space transform, which performances better while uses less resource. The paper demonstrates the advantages of the new algorithm by comparing with another two LUTs both in memory and speed.
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Computer Engineering. 2007, 33(16): 253-255. https://doi.org/10.3969/j.issn.1000-3428.2007.16.089A portable network performance measurement device is designed and implemented, in which Intel XScale PXA255 microprocessor and embedded Linux operating system are used. The FPGA device is applied to miniaturize the measurement device and to enhance its performance. The key techniques to solve the problems such as synchronization among devices, data exchange between network interface and CPU, data analysis and visualization are discussed.
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Computer Engineering. 2007, 33(16): 256-258,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.090This article explains the necessity of business rules management in telecom corporation from practice application, analyses the problems existed in many business systems, gives a design and implementation method of business rules management, and applies rule engine in telecom settle and apportion system. This system has been put into practical use and works well.
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Computer Engineering. 2007, 33(16): 259-260. https://doi.org/10.3969/j.issn.1000-3428.2007.16.091With the development of distributed interactive simulation, the security of simulation-data transmitting is becoming more and more important. Therefore, an embedded-PKI-simulate-platform is designed and implemented, which includes three parts: management software on windows, embedded software for security and network hardware. It also chooses the hybrid reliable multicast infrastructure to insure the efficiency of data transfer. The system is tested at several places, and experimental results show that the system has greatly improved the security.
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Computer Engineering. 2007, 33(16): 261-263. https://doi.org/10.3969/j.issn.1000-3428.2007.16.092This paper presents a design of real-time remote replication system based on LVM after discussing the characteristics of all kinds of approaches of the remote replication, which is an asynchronous and on-line remote replication system purely implemented by software in the existed IP network. And the system provides an easy and economic approach for the remote disaster tolerance technology without any expensive hardware.
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Computer Engineering. 2007, 33(16): 264-266. https://doi.org/10.3969/j.issn.1000-3428.2007.16.093In the field of the human-computer dialog more tasks to be furnished and humanistic requests about computer result that the size of software about the human-computer dialog is more greatness and that the structure is more complex, so the software engineers are called for working hard. In that condition, the human-computer dialog system frame based on agent is studied. It is effective for decomposing many tasks and sharing information of the system. The human-computer dialog of English study based on this frame is designed.
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Computer Engineering. 2007, 33(16): 267-268,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.094Application of WebGIS technology based on B/S mode is limited in a few using functions because it is still not mature, but real fuction requirements are increasing. To reconcile this conflict, the paper analyses the architecture of WebGIS technology based on B/S mode and brings forward the method of enhancing its functions based on temporary layers. The paper describes how to use temporary layers to help WebGIS realize key points development and how to apply this method in schedule management system of a oil plant production to realize complicate requirements. The application shows this method extends the range of WebGIS and fit for users’ requirements to a certain degree .
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Computer Engineering. 2007, 33(16): 269-271. https://doi.org/10.3969/j.issn.1000-3428.2007.16.095This paper designs and implements on-line expansion function in RAID system base on Linux, which allows RAID system to keep receiving requests from user while expanding. This function promotes the usability of the system. It also describes the implementation of on-line characteristic while using the simple method for RAID structure expansion and the solution to deal with the conflict between data migration and user’s requests. Experiments show that on-line expansion is stable in a long time running and the performance is acceptable.
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Computer Engineering. 2007, 33(16): 272-273,. https://doi.org/10.3969/j.issn.1000-3428.2007.16.096This paper designs and implements a medical assist expert system based on object-oriented method. While designing the inference engine, some new concepts are defined according to the characteristic of medicine assist field, such as description edge, arbitration edge and arbitration path. And these concepts are used as heuristic information to reason, in order to gain more credible solution. The knowledge database and inference engine of the system are separate, so it is universal for medicine assist field.
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Computer Engineering. 2007, 33(16): 274-276. https://doi.org/10.3969/j.issn.1000-3428.2007.16.097Since most estimation methods are based on the number of software codes, the function of software and the difficulty of software can not be computed exactly because of many uncertain factors, whice can not be accepted by customers easily. This paper analyses the software cost estimation method and puts forward a new software cost estimation method of Web system development——man/day estimation method, which computes the software cost by estimating the man/day of different level technicians and market level of wages without estimating complex codes, function and technical difficulty.
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Computer Engineering. 2007, 33(16): 277-279. https://doi.org/10.3969/j.issn.1000-3428.2007.16.098An embedded network project based on TMS320DM642 is proposed, which realizes a 100Mb/s network interface in massive signal processing, including hardware connecting means of plot of pane and software flowchart. Some related problems in developing the DM642 network interface are discussed, such as hardware-software compatibility, initialization, interruption and synchronization, out of memory, etc. The ways to solve these problems are put forward too.
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Computer Engineering. 2007, 33(16): 280-282. https://doi.org/10.3969/j.issn.1000-3428.2007.16.099The assignment description language provides an XML-based approach to partitioning, representing and processing the semi-structured assignment data in the Web-based assignment management systems of distance education, and it can provide a technology specification for heterogeneous assignment management systems to exchange assignment documents with each other. This paper introduces the designing process and using method of the assignment description language based on XML schema, and it also discusses the processing methods of the validation, display and storage of assignment’s XML document.
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Computer Engineering. 2007, 33(16): 283-285. https://doi.org/10.3969/j.issn.1000-3428.2007.16.100Based on a lot of research experiments, this paper proposes the algorithm of orthogonal double axle solution for granulated objects, which has been put into practice and proved in the application of auto-separation system for watermelon seeds. This algorithm has the advantage of low time complexity and high precision compared with others. It can also be used in the solution of other similar granulated objects with orthogonal double axle, and has a widespread application value.
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