20 October 2006, Volume 32 Issue 20
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Computer Engineering. 2006, 32(20): 1-3,61. https://doi.org/10.3969/j.issn.1000-3428.2006.20.001Image compressing by wavelet method is usually the embedded compression. Every wavelet coefficient is scanned many times in the compressing. It can spend more time than no embedded algorithm. The variable depth embedded compression of natural images is proposed in this paper. By the decay of the magnitude of the wavelet coefficients across subbands, the embedded algorithm can only scan parts of wavelet subbands, that is variable depth embedding. The experimental results show that the speed is faster than the previous schemes.
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Computer Engineering. 2006, 32(20): 4-6. https://doi.org/10.3969/j.issn.1000-3428.2006.20.002This paper proposes a novel Naïve-Bayes document classification method based on the set of concept feature vectors. It produces some initial classes from the set of unlabeled Web documents by SOM clustering and distributes a label for each, and builds the corresponding concept feature vector for each initial class using the maximum entropy method. It builds the last CFV-NB document classifier based on the space of concept feature vectors.
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Computer Engineering. 2006, 32(20): 7-9,12. https://doi.org/10.3969/j.issn.1000-3428.2006.20.003After reviewing the current early warning researches, this paper presents that most of current early warning methods are unsuitable because of lacking a historical “ill-represented” dataset. And then the support vector data description early warning technique based on kernel method is proposed to solve the problem. A one-class classifier is fitted to detect the “ill-represented” data objects by enclosing all “good” data objects in a hypersphere. If an object is outside the boundary of the hypersphere, an early warning expert would be prompted to decide whether the object is enough “ill-represented” for issuing a warning. An early warning experiment based on the macro-economic dataset of Jiangmen, Guangdong is conducted to verify the proposed technique.
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Computer Engineering. 2006, 32(20): 10-12. https://doi.org/10.3969/j.issn.1000-3428.2006.20.004In order to describe the user’s interest more exactly and provide for him what he needs, a new method to weight and optimize the user’s characterized interest in information filtering is presented. The paper defines the weights of the terms according to the order of the proposed sequence, optimizes the interest with synonyms in rough set theory, calculates the semantic similarity between interest and documents to be filtered, sorts them in descending order of their similarity, and submits them to the user. Experiments show that it has the higher precision.
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Computer Engineering. 2006, 32(20): 13-15,2. https://doi.org/10.3969/j.issn.1000-3428.2006.20.005The paradigm of proxy signature is a method for an entity to delegate signing capabilities to other participants so that they can sign on behalf of the entity. Proxy signature is an important cryptographic protocol, however, there are only few provable secure proxy signature schemes. In this paper, a new provably secure proxy signature scheme based on Gap Diffie-Hellman (GDH) group is proposed.
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Computer Engineering. 2006, 32(20): 16-17,4. https://doi.org/10.3969/j.issn.1000-3428.2006.20.006The manual production of vector topographic maps can be a time consuming and costly process. In this article, based on the river characteristics on topographic maps, an improved Snake model is employed to extract river. Through statistical analysis of river structural feature on topographic map, river primitives are searched. Utilizing automated tracking function of an improved snake model extracts river finally. Validity of this algorithm is verified by experimental results.
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Computer Engineering. 2006, 32(20): 18-21. https://doi.org/10.3969/j.issn.1000-3428.2006.20.007Particle swarm optimization is an evolutionary search technique motivated by the behavior of social organisms. Quantum oscillator model of PSO algorithm is established and a method of parameter control is provided in this paper, and a new swarm intelligence algorithm (QOPSO)is designed. The vast number of experiment results show that the new swarm intelligence algorithm has much stronger global searching ability compared to the classical PSO algorithm.
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Computer Engineering. 2006, 32(20): 22-24,4. https://doi.org/10.3969/j.issn.1000-3428.2006.20.008This paper proposes a new model of dynamic fuzzy kohonen neural network(DFKCN) which is applied to the text clustering. The model DFKCN is used in Chinese text clustering. The text eigenvector is represented by using the latent semantic analysis (LSA), which embodies the semantic relation of the eigen words, and realizes the dimension reduction of the eigenvector. The experiment shows both the precision and the efficiency of clustering DFKCN are higher than those of TGSOM.
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Computer Engineering. 2006, 32(20): 25-27,3. https://doi.org/10.3969/j.issn.1000-3428.2006.20.009This problem is relieved in some measure, but not solved fundamentally. An improved back-projection is proposed in this paper that can suppress background interference of object model fundamentally. A normalized histogram is produced in object model. An indexed list is built, the index variable is the gray value and the index content is the histogram value. A back-projection gray image is created by searching the indexed list by the input image color value. Mean-shift finds the local maxima to locate the object near the neighborhood of object center in the previous frame. Experimental results show the algorithm can track the moving object precisely in real-time.
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Computer Engineering. 2006, 32(20): 28-29,1. https://doi.org/10.3969/j.issn.1000-3428.2006.20.010A directly solving posterior probability method is presented for probability output of SVM in the multi-class case. The differences and different weights among these two-class SVM classifiers, based on the posterior probability, are considered and given for the combination of the probability outputs. The simulation experiment results show that the directly solving posterior probability method achieves the better classification ability and the better probability distribution of the posterior probability than the voting method and the Pairwise Coupling method.
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Computer Engineering. 2006, 32(20): 30-32. https://doi.org/10.3969/j.issn.1000-3428.2006.20.011A two-stage robust algorithm of singular points detection based on orientation features of fingerprint images is proposed. Candidate small blocks which may contain singular points are located with the integrated method of improved Poincaré index calculation with the orientation distribution analysis of the block orientation images; Local orientation variance in the candidate blocks is computed and used to locate the position of singular points accurately. The algorithm is evaluated with images from FVC2004 DB1_A database and the experimental results prove the method accurate and efficient.
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Computer Engineering. 2006, 32(20): 33-34,8. https://doi.org/10.3969/j.issn.1000-3428.2006.20.012While building service oriented Web application, it is necessary to search domain related Web services. Current search in UDDI servers is based on taxonomy of tModel and keyword-matching, which is not convenient to find domain related Web services. By crawling WSDL files directly from the Internet, and utilizing support vector machine to build WSDL file classifier, a method is proposed to realize domain based Web services search. Experiment shows that the method has a good accuracy.
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Computer Engineering. 2006, 32(20): 35-37. https://doi.org/10.3969/j.issn.1000-3428.2006.20.013In grid environment, the quality of service assurance by SLA is becoming more and more important. Service level guarantee relies on the amount of resource allocated. And the large traffic variations of grid service complex the relationship. This paper formally defines and analyzes these relationships and presents a constrained mathematical model for resource allocation. It also presents the on-demand resource allocation framework which can guarantee the service level and adapts to environmental changes. The simulation results show that the model and framework are practical and efficient.
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Computer Engineering. 2006, 32(20): 38-39,7. https://doi.org/10.3969/j.issn.1000-3428.2006.20.014A user access pattern clustering algorithm is researched according to search engine query log. It is explained that Jaccard coefficient and weighted similarity computation are not suitable for user access pattern clustering. A kind of improved Hamming distance computation formula is put forward; the clustering algorithm that uses Hamming distance to measure the similarity is given. After analyzing the algorithm, the result is concluded that this algorithm based on bipartite graph and improved Hamming distance computation formula is exact and efficient.
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Computer Engineering. 2006, 32(20): 40-42. https://doi.org/10.3969/j.issn.1000-3428.2006.20.015PowerPC-based NC systems are gradually put into action, but the corresponding tools of runtime performance monitoring for these NCs are not yet developed. Two problems must be resolved for the collection of PowerPC-NC system runtime performance parameters: one is the collecting kernel data and the other is communication between user space and kernel space. Performance parameter collecting methods in Linux are researched and the virtual-device-driver method based on LKM is proposed. Based on this collecting method a data collection module of PowerPC-NC system is designed and implemented, which can collect the performance parameters of NC server. Experiment results indicate that this tool has a high effectiveness and is easy to be used.
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Computer Engineering. 2006, 32(20): 43-44,7. https://doi.org/10.3969/j.issn.1000-3428.2006.20.016With the huge amount of information available online, the World Wide Web is a fertile area for data mining research. This paper addresses the issues related to data extraction from Web pages, and strongly suggests an XML-based approach for solving it. This paper describes the motivations behind converting semi-structured HTML documents into well-formed XML and presents a portion of conversion source codes that is developed based on HTML Tidy library, illustrates how to extract desired information from Web pages with XML technologies, including XHTML, XSLT and XQuery. It also discusses other aspects in the Web mining project such as data check and data integration.
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Computer Engineering. 2006, 32(20): 45-47. https://doi.org/10.3969/j.issn.1000-3428.2006.20.017In distributed peer-to-peer environment, the replica of data object can be used to improve availability and performance. To guarantee consistency, update conflicts that arise in such a system must be detected and resolved. Optimistic replication is a way to preserve consistency and relax the constraints on ordering. This paper proposes a formal model. And applying this model, it proposes the basic condition that guarantee consistency, proposes an algorithm that should be optimization in order to guarantee consistency, and extends the model to make it more suitable for real environment.
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Computer Engineering. 2006, 32(20): 48-50. https://doi.org/10.3969/j.issn.1000-3428.2006.20.018Most of the algorithms of approximate string match are designed for small or middle size of character set. Until now, people can’t find any efficient algorithms for searching of multiple patterns of large size of character set. This paper presents an algorithm——MBPM-BM, which can be used for searching of multiple patterns. Experimental results show that MBPM-BM works well in practice especially in chinese characters match.
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Computer Engineering. 2006, 32(20): 51-52. https://doi.org/10.3969/j.issn.1000-3428.2006.20.019With the increase of Web services on the Internet, how to compose the existing services to satisfy the individual requirements becomes a hot research focus. A new solution for composing Web services through theorem proving is put forward by importing linear logic tools. The automatic composing flow of Web services is obtained according to the proof process. In the end, the validity of the new method is also proved by an example.
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Computer Engineering. 2006, 32(20): 53-55. https://doi.org/10.3969/j.issn.1000-3428.2006.20.020Aiming at the disadvantage of traditional, this paper presents close coupling Web application system model based on a J2EE and loose coupling multi-storey distributed system, which separates business logic layer from database layer. It implements system configuration, data transmission, inter-layer interface with XML technology. A data transfer strategies between XML documents and heterogeneous data source is discussed and implemented. The architecture is applied to the Web application system——MEDLOG.
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Computer Engineering. 2006, 32(20): 56-58. https://doi.org/10.3969/j.issn.1000-3428.2006.20.021The multiversion-validation information(MV-VI)data broadcast mechanism with invalidation report is proposed that combines multiversion optimistic concurrency control protocol(MVOCC). Various multiversion broadcast disk organizations are introduced. The MI-VI data broadcast mechanism supports disconnection. During broadcast cycle, the global validation information(VI)of transactions is broadcasted. The fast invalidation reports(FIRs)are inserted after the IR to broadcast frequently updated data. Detailed simulation experiments are carried out to evaluate the proposed multiversion data broadcast mechanism. The results reveal that the performance of the MV-IV data broadcast mechanism is significantly better than other methods.
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Computer Engineering. 2006, 32(20): 59-61. https://doi.org/10.3969/j.issn.1000-3428.2006.20.022This paper puts forward the method of XML document based on linked-structure. It uses stream tokenizer to design an algorithm of HTML document parse. The element and text contents are inserted into the correct position to create DOM-parsing-tree as parsing. Lastly. After visiting the tree and storing the information into a binary-linked-list, it uses a modified preorder algorithm visiting the linked-list, then extracts corresponding information to build DTD and finish the whole generation process.
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Computer Engineering. 2006, 32(20): 62-64. https://doi.org/10.3969/j.issn.1000-3428.2006.20.023This paper puts forward an improvement on an enumeration algorithm of generation all heaps. Recursion judgement on left subtree and right subtree and judegment of hierarchy are combined to raise the efficiency of the algorithm. The test results indicate the validity and reliability of the algorithm.
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Computer Engineering. 2006, 32(20): 65-66. https://doi.org/10.3969/j.issn.1000-3428.2006.20.024According to the research of IoC pattern, this paper applies this pattern to the design of lightweight container. It describes the design of a lightweight container and the key steps in the process of implementing a lightweight container. It draws the picture of the use of lightweight container in the development of J2EE application. It gives the application, which show that the design is practical and efficient.
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Computer Engineering. 2006, 32(20): 67-68. https://doi.org/10.3969/j.issn.1000-3428.2006.20.025This paper proposes a new multi-granularities bi-temporal data model PMB, based on the classical HMAP model, by introducing the definition of transaction period parameter delay, to process the periodic data. The proposed model can efficiently deal with the problems of enormous record items and intersectant time points existing in the HMAP model, which will save the store space and improve the speed of searching for data. Theoretical analysis and experimental results show that the PMB model can make n items of the list cut short to a few items. When the value of n is very enormous, the advantage of this model is very prominent.
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Computer Engineering. 2006, 32(20): 69-71. https://doi.org/10.3969/j.issn.1000-3428.2006.20.026In order to optimize storage of objects in OSD, this paper proposes a smart object file system for OSD:SOFS, it is a file systems container, it can contain several file systems for different applications. At present, it contains two file systems: general object file system and media object file system, one is for small objects such as general document, Web and so on, the other is for large media objects. The experiment results show that when read or write small objects such as common documents, SOFS that is implemented in Linux kernel outperforms ext2 about 10%, and when read or write large media object, it outperforms ext2 about 30%.
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Computer Engineering. 2006, 32(20): 72-74. https://doi.org/10.3969/j.issn.1000-3428.2006.20.027Transaction process is the necessary basis for constructing enterprise application. While the development of technique and the broad application in enterprise information integration, Web service has become the mature technique for building successful enterprise application. But all those implementing Web service projects only support transaction process by explicitly coding using traditional Web technique or by making the background information system read only to forbid transaction. This paper details how to extend JTA transaction to enable the propagation of JTA transaction and preserve its ACID properties among Web services.
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Computer Engineering. 2006, 32(20): 75-77. https://doi.org/10.3969/j.issn.1000-3428.2006.20.028Object-oriented coupling is one of the important internal attributes of software quality. This paper firstly analyses the limitations of the existing static coupling measurement because of using inheritance and polymorphism, then defines the coupling metrics describing system run-time coupling, which based on UML sequence diagram which used to dynamic modeling, and validates the operability and practicability of this definition by a simple example.
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Computer Engineering. 2006, 32(20): 78-80. https://doi.org/10.3969/j.issn.1000-3428.2006.20.029The main idea of component-based software development (CBSD) is to use existing components for building up software systems. However the features of components result in a great number of difficulties in testing such systems. B. Meyer defines the relationship of component and client code as a formal contract, which firmly restricts the rule of interaction among component objects. Monitoring and checking a contract can easily find the interaction errors among a pair of components. This paper proposes a component integration test framework based on contract checking, contract-checking test framework(CCTF). And discuss the principle of contract checking, five function modules, testing process, and some relevant crucial techniques in applying CCTF to implement components-based software test platform.
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Computer Engineering. 2006, 32(20): 81-83. https://doi.org/10.3969/j.issn.1000-3428.2006.20.030TPC Benchmark™ C (TPC-C) is an OLTP workload, which is considered as performance evaluating standard. Kylin is a server OS in Chinese with owned authority based on the POSIX standard. To evaluate Kylin’s performance, a TPC-C testing system is needed. At present, most open source-test softwares, which attempt to implement OLTP are load test tools, and few of them accords with TPC-C benchmark. Hence, can’t gain the performance metric for TPC-C. The singularity of the test results and the opacity of the test course make it difficult to improve the operatiing system. This article implements TPC-C benchmark with Tuxedo, Apache and Oracle on Kylin OS.This system strictly keeps to TPC-C benchmark, reduces the impact because of the shortage of the testing software, and gives suggestion for Kylin.
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Computer Engineering. 2006, 32(20): 84-85. https://doi.org/10.3969/j.issn.1000-3428.2006.20.031Presently, acquisition of user browsing is one of the major topics on Web Log mining. According to the important character of user browsing, a way of applying rough set acquisition rule is presented. Important character is selected as condition properties, then through arithmetic ultimate rule was acquired, instance analysis effect turns to be well. In this way, just in virtue of simple data pretreatment, simple and effective access pattern can be obtained.
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Computer Engineering. 2006, 32(20): 86-88. https://doi.org/10.3969/j.issn.1000-3428.2006.20.032Data integration is an important problem in building computer applications. This paper introduces and implements a plug-in based solution of heterologous data integration on application systems. In this solution, “data access plug-ins”, which are known as data interfaces, are used to gain heterologous data from different systems and reform these them into unified format according to the business requirements. After that, a framework is applied to manage and control these plug-ins dynamically and consistently. Thanks to the technology of plug-ins, this extendable solution of system integration gains more flexible and dynamic features.
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Computer Engineering. 2006, 32(20): 89-91. https://doi.org/10.3969/j.issn.1000-3428.2006.20.033This paper introduces the designing method of the distributed database based on Oracle, besides the long-distance accessing technology of Oracle database and the mechanism of distributed transaction are discussed deeply, expatiates the realizing process of distributed database technique in large appliance enterprise’s employee wage-system construction design and businesses handle with search. By introducing the distributed technology, it puts the databases on different points as a logical whole, data consistency, integrity and safety all can be realized, which will increase the governing efficiency of the information, and designs a safe, reliable, efficient distributed database application system according to its actual requirement.
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Computer Engineering. 2006, 32(20): 92-94. https://doi.org/10.3969/j.issn.1000-3428.2006.20.034This paper applies a method of DNA sequence analysis in computational biology to text classification, and puts forward a text classifying method called SSAM by analyzing the signature sequences generated by a document collection. The experimental result on Reuters21578 and the comparison with several other text classifying methods prove SSAM has a better performance than Naive Bayes, and has a rapid classifying speed.
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Computer Engineering. 2006, 32(20): 95-96. https://doi.org/10.3969/j.issn.1000-3428.2006.20.035With the development of computer technology, lately some malicious code use the leak of Windows(2000/XP) kernel design to hide their processes. In order to detect the hidden processes created by malicious code, a new technology has been described with the example of program. The technology involved includes: the kernel process environment block(KPEB), the kernel thread environment block(KTEB), the mechanism of traditional processes detection and dispatcher.
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Computer Engineering. 2006, 32(20): 97-99. https://doi.org/10.3969/j.issn.1000-3428.2006.20.036This paper gets into the research on how to crawl information effectively in some sections of Web, which is also called parallel Web crawling technology, and brings forward a structure design model of the parallel incremental Web crawler. In order to download Web pages in parallel, the means of multiple thread and the latest character of Java language are adopted, meanwhile the paper adopts the right means for URL dispatching to make sure that threads would work in parallel with page analysis. In order to reduce redundancy, the method chooses footprint algorithm and extracts URL for threads to download. The test result proves the expect. It can effectively improve information gathering performance.
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Computer Engineering. 2006, 32(20): 100-102. https://doi.org/10.3969/j.issn.1000-3428.2006.20.037Service-oriented architecture(SOA) is a coarse-grained, loosely coupled system architecture which supports dynamic enterprise application integration. A SOA reference model (SOA-RM) cored with service enactment engine (SEE) is presented. By analyzing the genetics medical resource net project and specializing this reference model, one integration support system is designed based on SOA that is used to implement effectively dynamic enterprise application integration.
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Computer Engineering. 2006, 32(20): 103-105. https://doi.org/10.3969/j.issn.1000-3428.2006.20.038On the base of maintaining the consistence of global snapshot, the flow control needs to satisfy the low thought-out, short waiting time and low cost in WAN. The fault tolerant system provides the low cost of ov or editing document on the foundation of editing distance and editing similarity during the process of editing, optimizing the real time editing system in WAN. The algorithms are put forward about flow control. Then its performance in the system is analyzed by tool of OPNET.
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Computer Engineering. 2006, 32(20): 106-107. https://doi.org/10.3969/j.issn.1000-3428.2006.20.039According to the characters of grid computing and Master-Worker parallel computing, it is convenient to solve these problems in grid. Bifang computing platform of scavenging grid which can mask resource heterogeneity and distribution is a system using scavenging grid to do Master-Worker parallel computing. This paper introduces the framework of this computing platform and makes some research on resource descriptions and assignment algorithms in grid.
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Computer Engineering. 2006, 32(20): 108-110. https://doi.org/10.3969/j.issn.1000-3428.2006.20.040Based on the research of international standard and the network condition for China Unicom, the basic need for the integrated location-based service platform(ILBSP) is analyzed. Key technologies to realize ILBSP are presented, including the select policy for different location technique and cache function for location process. ILBSP can provide location services to code division multiple access(CDMA) user and global system mobile(GSM) user. This paper proposes a scheme to design and implement the platform including software architecture, hardware architecture and process topology. The scheduling method used by the main module is also presented. And the performance of platform is explained.
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Computer Engineering. 2006, 32(20): 111-113. https://doi.org/10.3969/j.issn.1000-3428.2006.20.041A analysis method of finite open queuing network based on the maximum entropy method (MEM) is presented. This algorithm is used to evaluate the performance of an asynchronous 32-bits pipeline multiplier. The result of the algorithm is compared with the result of Modelsim simulation of the multiplier. The percentage error is small. So the algorithm is proved to be effective for the performance evaluation of asynchronous pipelines.
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Computer Engineering. 2006, 32(20): 114-116. https://doi.org/10.3969/j.issn.1000-3428.2006.20.042Current anonymous systems are mainly based on the specific applications. Due to the different needs and methods of different specific applications, there are some disadvantages in current anonymous systems, such as redundant functions, poor interoperability and poor reusability. This paper presents the architecture of a general forward-based anonymity system using the mechanisms of layering. Seven reusable components are designed in the architecture. Also the paper describes algorithms of realizing some primary components.
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Computer Engineering. 2006, 32(20): 117-119. https://doi.org/10.3969/j.issn.1000-3428.2006.20.043Protocol conformance test is an important means to ensure correct functioning and high efficiency of the protocol implementation. After introduction of RIPng protocol, this paper proposes the multi-port test structure which is suitable for the RIPng conformance test. It adopts the traverse test method to test the RIPng implementation and designs its test suite as well as the corresponding RI. Further more, it practises RIPng conformance test on seven routers for CNGI.
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Computer Engineering. 2006, 32(20): 120-122. https://doi.org/10.3969/j.issn.1000-3428.2006.20.044
In these years, storage virtualization, intelligent storage, zero-copy technology NAS and SAN integration, and information life-cycle management are rapidly developed new techniques in network storage field. This paper analyses their backgrounds and main characteristics, points out their present application states and future developing trends.
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Computer Engineering. 2006, 32(20): 123-125. https://doi.org/10.3969/j.issn.1000-3428.2006.20.045The routing protocol is one of the key researching techniques for wireless sensor network, and the data-centric routing protocol is the hotspot of study at present. Based on locality updating mechanism, the data-centric Directed Diffusion protocol is improved. In different simulation scenes of different parameters, the improved protocol depicted by C++ is simulated on the NS2 platform. Compared with the performance of Directed Diffusion protocol, the improved protocol has less delay and overhead.
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Computer Engineering. 2006, 32(20): 126-128. https://doi.org/10.3969/j.issn.1000-3428.2006.20.046With the explosion of the IP network service, such as NGN, 3G, transiting to the IPv6 network is on the agenda. Using tunnels is the most easily method to choose. However, NAT devices in the path will be a big tough thing in the transition to IPv6 network. This paper focuses on how to across the NAT device using IPv4 UDP tunnel after analyzing the normal tunnel mechanism and Teredo tunnel, then produces the application method of fixed network and GPRS network.
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Computer Engineering. 2006, 32(20): 129-131. https://doi.org/10.3969/j.issn.1000-3428.2006.20.047To provide solution to the congestion problems, a single nerve cell adaptive PID control mechanism, which is based on the probability drop scheme of the network node, is proposed and analyzed. Simulation that runs on the OPNET software is carried out on single node traffic model. The simulation results show that the mechanism proposed works well in terms of stability of the average queue size and system robustness.
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Computer Engineering. 2006, 32(20): 132-134. https://doi.org/10.3969/j.issn.1000-3428.2006.20.048Grid is composed of several thousands of users from different organizations sharing their resources. Controlling access to these resources is a difficult problem and traditional access authorization is not applicable to a large scale environment. This paper describes a lightweight authorization service developed to solve this problem in the project requirements: data access control service (DACS). DACS divide VO users into different levels and resources only maintain access control policies to all users in same level as a whole.
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Computer Engineering. 2006, 32(20): 135-137. https://doi.org/10.3969/j.issn.1000-3428.2006.20.049Junk code transformation is one of effective approach of the code obfuscation technology. Based on the analysis of current junk code strategies, this paper presents a new method named stochastic junk code encryption algorithm, and depicts the algorithm with formal language. The paper studies how to prove the logic invariability of junk code transformation with formalization method. After studying the formal definition of junk code transformation, some lemmas are educed. With these lemmas, and from three aspects such as “JMP Expand”, “JMC Switch” and “Junk Code”, the paper proves that the program which transforms with stochastic junk code algorithm has the same logicality with the original program.
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Computer Engineering. 2006, 32(20): 138-139. https://doi.org/10.3969/j.issn.1000-3428.2006.20.050Distributed object based intrusion tolerant system (ITDOS) has become one of the attractive issues on intrusion tolerance. There have been many significant researches on the model of a heterogeneous intrusion tolerant distributed object system, but few of them focus on distributed object recovery strategy. This paper presents a model of ITDOS based on middleware, CORBA, which is based on the researches of the SITAR model, and presents a recovery strategy for ITDOS in this model. The objects, recovered by the recovery strategy, can resist the attack of the last to some extent. It is validated by experiment that the strategy correctly performs forward recovery.
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Computer Engineering. 2006, 32(20): 140-142. https://doi.org/10.3969/j.issn.1000-3428.2006.20.051With the fast development of network, network information security systems (NISS) make a long progress. But performance evaluation for NISS is found to be challenging. The paper illustrates a new method based on the architecture of ServerScope to test NISS. To generate the interactive network traffic especially needed by NISS, some blades can play the role of the servers and some do the clients. This method makes up the disadvantage of replaying the same traffic and simplifies the testing environment so that it ensures that the implementation of test is easy and efficient.
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Computer Engineering. 2006, 32(20): 143-146. https://doi.org/10.3969/j.issn.1000-3428.2006.20.052A novel simple technique to build a table of variable-length patterns from training system call sequences is presented, aiming to find out a set of basic and relatively independent variable-length patterns. Also, the method finds out all possible relationship between variable-length patterns, and thereby generates an exact DFA representation of the program. Using the data sets from the university of New Mexico, the schema is evaluated by several targets—sizes of variable-length patterns, false positives and false negatives. The experimental results indicate that the algorithms generate a relative small set of patterns, and get very low false positives and false negatives.
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Computer Engineering. 2006, 32(20): 147-149. https://doi.org/10.3969/j.issn.1000-3428.2006.20.053One of the best covert channels providers in TCP/IP communication hiding is hypertext transfer protocol, which is the most widely used in Internet currently. The common method of HTTP information hiding is embedding data into HTTP packets’ payload directly, which leaves some obvious signatures. On the other hand, communication hiding algorithm based on HTTP protocol parameters sorting can encode the hidden information by sorting some special key words’ parameters emergence sequence. The algorithm will not insert additional information into the packets. To detect the re-sorting attack, some information integrity scheme is necessary.
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Computer Engineering. 2006, 32(20): 150-152. https://doi.org/10.3969/j.issn.1000-3428.2006.20.054This paper gives a NIDS model using basics of relational database. This model is established on distributed self-organized characteristics of natural immune systems. It stresses on intrusion selection, recombination, reproduction of artificial immune system. A k-mating algorithm is given. The result of the experiment proves that the model is effective.
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Computer Engineering. 2006, 32(20): 153-154. https://doi.org/10.3969/j.issn.1000-3428.2006.20.055The paper presents the general encryption approach. To address the synchronization problem of the voice communication, it uses the filter banks that can analysze and synthesize the voice. And it improves the algorithm proposed by Lee Shanlin. The approach not only reduces the computation cost but also deducts the redundancy data. Moreover, its effect is better than the algorithm proposed by Lee Shanlin as the result of software simulation.
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Computer Engineering. 2006, 32(20): 155-156. https://doi.org/10.3969/j.issn.1000-3428.2006.20.056Privilege management infrastructure is the research hotspot in the field of network security at present. How to improve the PMI system’s efficiency and how to standardize the access control policies are the main questions now. A condition based on access control policy and its implementation mechanism is improved by using XACML technology. Combined with J2EE technology, a PMI system based on the policy model is designed and implemented. The improved system resolves the questions above, provides convenient privilege management and fine-grained access control.
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Computer Engineering. 2006, 32(20): 157-159. https://doi.org/10.3969/j.issn.1000-3428.2006.20.057This paper proposes a model using CA plus symmetrical L2TP routers, the digital certificate fulfills identity-authentication and key distribution, the L2TP router fulfills encryption and data-intergrity. Compared with the present method using LAC plus LNS, the scheme distinguishes and simplifies the work, and it solves the problem that multiple calls in a L2TP tunnel are independently secure. After considering the feature of the Linux kenel, it designs the architecture of the L2TP router to deal with VPN data. The experiments show that the scheme gives attention to security and performance, it provides a speedy and authentic VPN solution.
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Computer Engineering. 2006, 32(20): 160-162. https://doi.org/10.3969/j.issn.1000-3428.2006.20.058A novel approach of dynamic graph software watermark protection with multiple constant encoding is proposed, and an algorithm to protect the watermark based on improved PPCT structure is designed and implemented. Through creating multiple dependencies of fake watermarks with the protected program, the algorithm presents many significant features, such as, tamper proofing, anti-attack, and effectiveness in watermark protection.
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Computer Engineering. 2006, 32(20): 163-165. https://doi.org/10.3969/j.issn.1000-3428.2006.20.059The vulnerabilities of software are the root of most security incident. When these vulnerabilities can be exploited, this has a serious impact. Analysis of vulnerability alerts as distributed by organizations like CERT or SANS shows that many vulnerabilities can be attributed to the same mistakes made by developers. This paper proposes a structured taxonomy of the origins of software vulnerabilities. Such a taxonomy can be used as an aid for developers to avoid common pitfall, as didactical material for students in software engineering or as a “checklist” for software testers or auditors.
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Computer Engineering. 2006, 32(20): 166-167. https://doi.org/10.3969/j.issn.1000-3428.2006.20.060Today, both IPSec technology and network address translator(NAT) technology are widely used in the internet, but these also take some problems and conflicts. In reference, Pan puts forward the traversal solution of IPSec-NAT to solve such conflict, however, the performance proposed in his paper is not quite ideal. This paper gives some efficient improvements which are based on Pan[1], and the method works well with multiple clients behind NAT trying to establish IPSec communications with a certain server simultaneously, at the same time, it improves performance to a great extent.
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Computer Engineering. 2006, 32(20): 168-169. https://doi.org/10.3969/j.issn.1000-3428.2006.20.061The secure distribution of the key is an important process of keeping the security of communication by using cryptographic technology. This paper introduces a protocol integrating Diffie-Hellman protocol into the digital signature standard, points out its weakness in perfect forward secrecy, proposes a new key exchange protocol and analyses its security and efficiency briefly.
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Computer Engineering. 2006, 32(20): 170-172. https://doi.org/10.3969/j.issn.1000-3428.2006.20.062To avoid HTTP attacks using automatic form-committing, the identifying code technique is widely used. A brief introduction of the types of identifying code techniques and its application is given. The principles of recognizing and attacking are discussed. Primary experiments suggest that quite a lot of identifying codes are not secure enough. Finally, some methods and schedules with OCR techniques for prevention are proposed.
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Computer Engineering. 2006, 32(20): 173-174. https://doi.org/10.3969/j.issn.1000-3428.2006.20.063The chaos is very sensitive to initial conditions and high-blooded randomicity, so it can be used in encrypt information. This paper introduces a new undeniable signature scheme based on chaos. The experiment results show that it has the characteristic of high security, being prone to implement.
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Computer Engineering. 2006, 32(20): 175-176. https://doi.org/10.3969/j.issn.1000-3428.2006.20.064To solve many problems in the current security products, such as low integration of these products, the complexity of management, incapable share of safe events and safe information, low utilization of many safe information resource and the difficulty of self-driven, this paper designs a self-driven model of security management policy. According to the model, it introduces its definition, criterion and implementation technologies.
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Computer Engineering. 2006, 32(20): 177-179. https://doi.org/10.3969/j.issn.1000-3428.2006.20.065A perfect security vulnerability collection model based on the notion of vulnerability auto-collection is proposed. This model updates the vulnerability database timely and collects vulnerabilities efficiently. The architecture and function module of the vulnerability auto-collection system are presented, and the specific implementation is given.
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Computer Engineering. 2006, 32(20): 180-182. https://doi.org/10.3969/j.issn.1000-3428.2006.20.066This paper researches the multiscale geometry analysis tool——Contourlet, and proposes a new Contourlet multi-threshold shrink method for image denoising. The algorithm combines hard-threshold with correlation among the subband layers of Contourlet transform. Thresholding is derived by both the numbers of coefficients in each transformed layer and the intensity of noises added to the original image, hard-threshold function is also adopted for image denoising. Comparing with traditional wavelet denoising methods, the algorithm achieves obvious improvement in both subjective visual effect and objective quality.
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Computer Engineering. 2006, 32(20): 183-184. https://doi.org/10.3969/j.issn.1000-3428.2006.20.067This paper proposes a sentence space model(SSM)and a classification algorithm based on SSM. It compares the vector space model and the sentence space model in classifying the same document with the recall and the precision from different granularity, word granularity and sentence granularity. Experiments show SSM has a better classification performance than vector space model in many circumstances.
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Computer Engineering. 2006, 32(20): 185-187. https://doi.org/10.3969/j.issn.1000-3428.2006.20.068This paper proposes PKDA, an effective method for finding personalized knowledge. By way of deleting the superabundant condition attributes ring upon ring, the interested information is discovered. It gives analyses and comparison of experiment results to illustrate the efficiency and feasibility of the algorithm.
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Computer Engineering. 2006, 32(20): 188-190. https://doi.org/10.3969/j.issn.1000-3428.2006.20.069Inspired by the biological immune mechanism, this paper designs an intrusion detection model based on immune agents, which uses the level construction of sensor and response scheme. The immunity-based agents are independent and collaborate each other and roames among network nodes to detect the distributed intrusions. It introduces the artificial immunization algorithm to seek the superior mechanism, the antibodies promotion and suppression technology, the update of memory, the affinity and the density. The experiment shows that this system guarantes the antibodies multiplicity, improves premature convergence.
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Computer Engineering. 2006, 32(20): 191-192. https://doi.org/10.3969/j.issn.1000-3428.2006.20.070The continuous value is discretized before using the rough set method to mine the classification rules. But more information concealed in the original data is lost after the discretization, the quality of the extracted classification rules is very poor. A new method based on self-organizing artificial neural networks and rough set theory is designed to extract classification rules of continuous value. Because self-organizing artificial neural networks can train themselves and make an auto-classification on the input mode, it is used twice to classify the data before and after discretization. It extracts the rules by rough sets reduction until the results of two classifications are consistent. Through the analysis of case studies, the rationality of the extraction rule is testified.
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Computer Engineering. 2006, 32(20): 193-194. https://doi.org/10.3969/j.issn.1000-3428.2006.20.071This paper proposes a new optimal algorithm of fork points in off-line handwritten Chinese character. The algorithm is processed after getting feature points by using Retoviz’ definition of crossing number. This algorithm improves maximum circle criterion, reduces further error rate of grouping fork point. Hence, improve the correct rate of off-line handwritten Chinese character recognition.
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Computer Engineering. 2006, 32(20): 195-197. https://doi.org/10.3969/j.issn.1000-3428.2006.20.072Affective and natural human-computer interaction is a challenging lesson in the field of computer application. According to the theory of need levels of Maslom, this paper develops emotional interaction system for virtual human, discusses physical need, safety need and their influence upon emotion and proposes an affective model combined with the theory of mood information of Siminov. It describes the realization of speech interaction system of virtual human. The results of experiment indicate that virtual human can interact with human in an affective and nature way.
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Computer Engineering. 2006, 32(20): 198-200. https://doi.org/10.3969/j.issn.1000-3428.2006.20.073A method that can gray images selectively is proposed and realized with Matlab. According to this method, any selected colour of an image can be converted to black, and the rest colours will be converted to higher gray values as their colour-distance to the selected colour increases. With this method, different information referring to different colours can be obtained from colourful images more easily. It’s helpful to colour-based image information processing.
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Computer Engineering. 2006, 32(20): 201-202. https://doi.org/10.3969/j.issn.1000-3428.2006.20.074A functional linked neural network is simple in its structure, and easy in its computation. In this paper, a multi-extended linked neural network is introduced to identify the fluctuant parameters of a nonlinear system. Its simulation result is remarkable.
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Computer Engineering. 2006, 32(20): 203-204. https://doi.org/10.3969/j.issn.1000-3428.2006.20.075Recently there has been a growing interest in speaker adaptive training(SAT). However, errors can often arise when estimating covariance matrices in the original SAT framework due to the lack of observations in some Gauss components. This paper presents a novel approach which applies maximum a posteriori (MAP) covariance-estimating into original SAT. Experimental results in Switchboard corpus demonstrate that the proposed method can deliver significant reductions in word error rate (WER) and raise the robustness of SAT process.
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Computer Engineering. 2006, 32(20): 205-206. https://doi.org/10.3969/j.issn.1000-3428.2006.20.076Question answering is an important field in artificial intelligence researches. But there are some limitations in traditional QA systems based on pattern matching. This paper analyzes and applies natural language process algorithms based on HMM, chart parsing, word dictionary and syntactic rules to extend dialogue management module, perform semantic analysis on users’ sentences to implement semantic blocks recognition, theme recognition and information distillation. Those algorithms can improve system’s process ability towards sentence analysis and overcome the disadvantages of traditional methods. The QA system is implemented on Java platform.
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Computer Engineering. 2006, 32(20): 207-209. https://doi.org/10.3969/j.issn.1000-3428.2006.20.077This paper summarizes the known hierarchical spatial reasoning procedure, for traffic network, adopts the strategy narrowing search region and the strategy of comparison, puts forward a new hierarchical spatial reasoning recursive procedure, improves the reliability of optimum path algorithm, and gives a necessary analysis about the efficiency of the optimum path algorithm.
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Computer Engineering. 2006, 32(20): 210-212. https://doi.org/10.3969/j.issn.1000-3428.2006.20.078Through analyzing the work of book weeding, it is known that to use the intelligent method in book weeding is very important. The neural network ensembles technology is a good idea for dealing with these problems. This paper presents a constructive method for training neural network ensembles. In training individual networks in ensembles, the proposed method not only adjusts the connection weights, but also makes the network architecture of the individual networks. So it improves the accuracy of the individual networks while increasing the diversity among the individual networks and decreasing the generalization error of network ensembles. Experiments prove that this ensemble is very effect in weeding books.
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Computer Engineering. 2006, 32(20): 213-215. https://doi.org/10.3969/j.issn.1000-3428.2006.20.079Some analysis is focused on each code block passing number of EBCOT (embedded block coding with optimized truncation) in JPEG2000. Through experiments on lots of images, a conclusion can be made that each code block truncates at similar code block passing numbers. Hence this paper addresses a truncation algorithm in the equal-coding pass. Furthermore based on the above algorithm, a progressive passing-number truncation coding algorithm (PPNTC) is proposed which discards complicated rate-distortion calculation and makes it easy for the design of T2 coder. This algorithm speeds up the processing of JPEG2000 and saves the memory cost. It can be realized more easily on hardware system. The system shows the developed scheme meets the high-speed requirement of the real-time coding 250fps.
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Computer Engineering. 2006, 32(20): 216-217. https://doi.org/10.3969/j.issn.1000-3428.2006.20.080It is a novel idea of video coding algorithm that represents color video in the mathematic model of four-dimensional matrix and encodes multiple frames of color video using four-dimensional matrix discrete cosine transform(4D-MDCT). A new color video coding method which combines 4D-MDCT and four dimensional intra prediction is proposed. The experimental results show that the proposed algorithm can improve the performance of color video compression based on 4D-MDCT further.
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Computer Engineering. 2006, 32(20): 218-220. https://doi.org/10.3969/j.issn.1000-3428.2006.20.081This paper analyses the research of application layer multicast in media streaming distribution, and designs scalable application layer multicast system for live media streaming. The system based on unstructured Overlay adopts the algorithm for node’s joining and message distribution mechanism which are both based on Gossip; It describes the strategy of data buffer and data acquisition. With the function of failure detection and recovery, the robustness of the system can be enhanced. The system can be implemented in ease and has good expansibility.
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Computer Engineering. 2006, 32(20): 221-223. https://doi.org/10.3969/j.issn.1000-3428.2006.20.082Stereo vision system is a vital part of the anthropomorphic robot. To satisfy the special requirement of the stereo vision system, a multi-thread video capture system based on DirectShow is proposed. The system is good development platform, which is simple and can be used to synchronically capture video streams of two same type of USB cameras.
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Computer Engineering. 2006, 32(20): 224-226. https://doi.org/10.3969/j.issn.1000-3428.2006.20.083An adaptive playout algorithm for MPEG1/MPEG2 video streaming is proposed. It scales the duration that each video frame is shown according to the occupied playout buffer level. On the types of arriving video frames basis the algorithm determines to temporary memory or discard the frames as the playout buffer is overflow. So the receiver could not lose intra-coded frames and predictive-coded frames. Experimental results show that the proposed algorithm has advantages over Yuang algorithm in discontinuity and distortion of playout and could make video streaming smoothly play out.
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Computer Engineering. 2006, 32(20): 227-229. https://doi.org/10.3969/j.issn.1000-3428.2006.20.084This paper presents 3D engine based on OpenGL which could be applied in shoot simulation system by using object-oriented technology to improve the developing efficiency of the system. The function model of 3D engine is analyzed according to the requirements of the shoot simulation system to define the main function of each module. It analyzes the structure model as well as introduces two important parts that consist the main body of the engine, namely scene management module and main control module. A brief introduction of the main concepts of the main structure of the engine is taken. This engine has been used in the development of shoot simulation system of infantry battalion weapon.
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Computer Engineering. 2006, 32(20): 230-232. https://doi.org/10.3969/j.issn.1000-3428.2006.20.085The paper focuses on object-oriented multimedia synchronization based on MPEG-4. By analyzing existing multimedia synchronization technology, the paper designs the layered structure synchronization model to synchronize all MPEG-4 multimedia objects, based on MPEG-4 system synchronized mechanism and the advanced synchronization model (FlexTime).
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Computer Engineering. 2006, 32(20): 233-234. https://doi.org/10.3969/j.issn.1000-3428.2006.20.086H.264 is the most advanced algorithm for video transmission and rate control technology is necessary and important to it. In this paper, a new algorithm based on JVT-G012 is proposed. The good of it is its ease and effectiveness to allocate bits for the macroblocks and the less relation to the setting of the coefficients because it can adjust the coefficients automatically according to the pictures being encoded.
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Computer Engineering. 2006, 32(20): 235-237. https://doi.org/10.3969/j.issn.1000-3428.2006.20.087The process and characteristic of machine tool’s collaborative design are studied. The process of machine tool’s collaborative design is described by UML. Layered structure of collaborative design support environment for machine tool is proposed. Support for collaborative design activity, support for organization and management of collaborative design group, and support for cooperation of collaborative design group are the three main factors of the collaborative design support environment. The framework of the support environment is set up where distributed structure is mainly used and centralized structure is secondarily used. The key technologies of the system are investigated, including task scheduling, collaborative constraint model, conflict resolution, etc. With these technologies a corresponding prototype system is partially developed.
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Computer Engineering. 2006, 32(20): 238-241. https://doi.org/10.3969/j.issn.1000-3428.2006.20.088Task schedule and management of machine tool’s collaborative design are studied and carried out. Task is decomposed by the means which combine function decomposition and structure decomposition. Unaided manipulation and coupling manipulation are used recursively in DSM to schedule task. Influencing factor of task assignment and the concrete arithmetic are studied. The layered and recursive task decomposition model of machine tool is proposed. In the end, implementation flow based on network of task schedule system is proposed and a corresponding prototype system is partially developed.
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Computer Engineering. 2006, 32(20): 242-243. https://doi.org/10.3969/j.issn.1000-3428.2006.20.089In this motional video surveillance system, MSTFP model is adopted to predict the next-time available bandwidth of CDMA. Based on it, referring to the design of the regulator in H.263 and the XVID codes, the scheme designs an auto-adapted rate-control strategy based on buffer capacity and feedback control. The experiment shows that the video speed and the channel rate obtain a good match, and provides a better transmission and display of the video.
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Computer Engineering. 2006, 32(20): 244-246. https://doi.org/10.3969/j.issn.1000-3428.2006.20.090The tracking terminal plays an important role in the navigation and positioning system. How to improve the performance and precision of the tracking terminal is a key problem to the designer and user. This paper presents a method which integrates GPS with GSM positioning technology in one terminal, and specifies the software and hardware design and implementation of the terminal.
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Computer Engineering. 2006, 32(20): 247-249. https://doi.org/10.3969/j.issn.1000-3428.2006.20.091
In mine or surveillance field of open country, or bad condition, it is fairly dangerous and unreliable for using computer and data collection card to implement surveillance tasks. This paper analyzes platform selection in special surveillance environment, and discusses communication method and compressing coding standard of surveillance data based on such problems as the high possibility of flammability and explosion, high humidity and lots of dust in surveillance environment, and the inconvenience of separate, long distance surveillance fields. It also puts forward the idea of establishing the embedded intelligent surveillance platform in rugged environment. Finally the design and implementation of this platform are introduced.
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Computer Engineering. 2006, 32(20): 250-252. https://doi.org/10.3969/j.issn.1000-3428.2006.20.092With the development of network technology, thin-client computation has become an important application model. This paper analyzes the print model of thin-client computation. According to the characteristic of the thin-client computing model and the personalized demand of end-users, a new model of terminal print for thin-client computation is put forward. A design and implementation of the model under Linux environment is presented.
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Computer Engineering. 2006, 32(20): 253-254. https://doi.org/10.3969/j.issn.1000-3428.2006.20.093
Real time data acquisition is very important on computer intelligent control. Based on data acquisition of the electric power system, this paper introduces the way of computer serial port data acquisition on Windows environment and the use of the multimedia timer on Delphi. Thus, the speed and the precision will be greatly improved.
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Computer Engineering. 2006, 32(20): 255-257. https://doi.org/10.3969/j.issn.1000-3428.2006.20.094The security situation of the coal mine is very severe, the accident rescue and command has met a challenges. Based on the description of component GIS and SMS technology, design thought of orthogonal software architecture modularization is proposed, and system design project based on GIS and SMS technology of the main function with accident monitoring and accident rescue management is provided, and the technology route of SMS component design is analyzed. This system has already been succeeded in developing and putting into the test run.
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Computer Engineering. 2006, 32(20): 258-260. https://doi.org/10.3969/j.issn.1000-3428.2006.20.095The paper introduces a hi-efficient coding/decoding method to apply AVR MCU to code/decode Manchester at 10kbps successfully, principle and communication protocol in wireless communicating systems of low power. It provides in detail a technique about how to identify initial flag, synchronization code and data.
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Computer Engineering. 2006, 32(20): 261-263. https://doi.org/10.3969/j.issn.1000-3428.2006.20.096The framework of the simulation system for fin-and-tube heat exchanger is established, with the help of the technology of database and visualization, and the distributed simulation model of the heat exchanger, the simulation system is realized. This simulation system includes three parts, such as input module, simulation module and output module. The parameters for the simulation system can be input conveniently through the input module, the heat exchanger simulation can be executed by the simulation module, and the simulation results can be output visually by the output module.
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Computer Engineering. 2006, 32(20): 264-266. https://doi.org/10.3969/j.issn.1000-3428.2006.20.097This paper discusses the design objective and function structure of project human resource management information system, and brings forward a practical solution for the implementation of system function based on modularization. It discusses influence of system function realization based on module partition, and demonstrates validity of the system.
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Computer Engineering. 2006, 32(20): 267-269. https://doi.org/10.3969/j.issn.1000-3428.2006.20.098
The actuality, problems, concept and application of urban emergency response system(UERS) are introduced. A new system framework and different functions of UERS based on service platform are discussed. By an actual example, the workflow, system structure, implement plan and key technologies are analyzed.
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Computer Engineering. 2006, 32(20): 270-272. https://doi.org/10.3969/j.issn.1000-3428.2006.20.099This article analyzes the often-used data synchronization technologies and according to specific features of digital campus, puts forward a new method of data synchronization. The method’s affectivity and the system’s extensibility are proved in practice. Then, the improvement measure of the system under the real time requirement is put forward.
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Computer Engineering. 2006, 32(20): 273-275. https://doi.org/10.3969/j.issn.1000-3428.2006.20.100Government information resource management (GIRM) is defined as technology, economy and culture environment management varied with time. From the view of technology, the government information resource planning (GIRP), which is based on OAGIS and Web service, is architected to safely and efficiently integrate and share government information resource (GIR), which implements integration by use of SOAP and OGAIS and reconfiguration by use of WSDL, OAGIS and Web service, and workflow and safety management by use of Web service transaction processing and safety criterion.
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Computer Engineering. 2006, 32(20): 276-278. https://doi.org/10.3969/j.issn.1000-3428.2006.20.101As the voice services become more and more diversified, the traditional DSP techs cannot satisfy the complex service requirements because they can only deal with the voice data simply. This paper presents a solution based on the communication processor MPC860 and the DSP chip TMS320VC5509 to realize a multi-channel real time voice communication design, and mainly analyzes the QMC driver as the key module. This solution has now been used in practice, and can satisfy the requirements of multi-channel communication and multiple voices mix well.
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Computer Engineering. 2006, 32(20): 279-281. https://doi.org/10.3969/j.issn.1000-3428.2006.20.102With lots of medium and small companies adopting Web application technology for their enterprise information system(EIS), there is need for a good performance/price ratio Web server load balancer. On the one hand, the limited function of DNS round robin can’t meet with the requirements; on the other hand, the companies can’t afford the high cost of the hardware balancer. Aiming to this dilemma, an effective Web server load balancer based on Servlet technology of J2EE platform has been presented.
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Computer Engineering. 2006, 32(20): 282-283. https://doi.org/10.3969/j.issn.1000-3428.2006.20.103ASICs are widely used in electronic products because of their programmability and convenience of design. Some ASICs have nonstandard serial communication interface that can’t communicate with PC directly. The realization of serial communication between PC and ASIC is introduced, in which a micro-controller is used as the communication bridge. That is, its P1.0~P1.3 ports are simulated as synchronous a clock wire, two serial in and out wires and a control wire of ASIC.
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Computer Engineering. 2006, 32(20): 284-285. https://doi.org/10.3969/j.issn.1000-3428.2006.20.104Virtual digital machine is system software of simulation real computer function. This paper introduces the design idea framework structure and key technnologies of virtual digital machine system(VDM), gives application and instance based on VDM, the test results show validity of the design.
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