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CN 11-2296/TP
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Edited by: Editorial Board of Journal Of Computer Science and Technology
P.O. Box 2704, Beijing 100190, P.R. China
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  • Table of Content
      15 September 2001, Volume 16 Issue 5 Previous Issue    Next Issue
    For Selected: View Abstracts Toggle Thumbnails
    Comparative Study of Two Flow Control Mechanisms in High Speed Networks
    ZHANG Xiaolin(张孝林),DU Haining(杜海宁),WU Jieyi(吴介一),ZHANG Sabing(张飒兵)and FEI Xiang(费翔)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(264KB) ( 1665 )   Chinese Summary
    Considerable protocol development efforts in recent ATM (Asynchronous Transfer Mode) Forum activities have been focused on the traffic management of available bit rate (ABR) service. It has been shown that ABR service enables persistent, greedy data sources to efficiently utilize ATM network resources with the help of a rate-based flow control mechanism. ATM Forum Traffic Management Specification Version 4.0 document gives a complete description of the end system behavior of the flow control mechanism, but it leaves the details of the switch behavior to be vendor-implementation dependent. For the sake of compatibility and interoperation among flow control mechanisms implemented by vendors, two rate-based mechanisms EPRCA (Enhanced Proportional Rate Control Algorithm) and ERICA (Explicit Rate Indication for Congestion Avoidance) have been recommended in the specification. In this paper, the mechanisms are studied and their performance is analyzed and compared with a material network. Simulation shows that ERICA is significantly better than EPRCA in the performance of steady state and instantaneous state of source end system ACR (Allowed Cell Rate) and buffer queue of bottleneck switch.
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    Improved Relevance Ranking in WebGather
    LEI Ming(雷鸣),WANG Jianyong(王建勇),CHEN Baojue(陈葆珏)and LI Xiaoming(李晓明)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(297KB) ( 1377 )   Chinese Summary
    The amount of information on the web is growing rapidly, and search engines that rely on keyword matching usually return too many low quality matches. To improve search results, a challenging task for search engines is how to effectively calculate a relevance ranking for each web page. This paper discusses in what order a search engine should return the URLs it has produced in response to a user's query, so as to show more relevant pages first. Emphasis is given on the ranking functions adopted by WebGather that take link structure and user popularity factors into account. Experimental results are also presented to evaluate the proposed strategy.
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    A Pragmatic Behavior Subtyping Relation Based on Both States and Actions
    WANG Shengyuan(王生原),YU Jian(喻坚)and YUAN Chongyi(袁崇义)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(333KB) ( 1512 )   Chinese Summary
    A behavior preserving relation between Petri-net systems is introduced in this paper, based on the observability of both places and transitions, which is important in modeling the dynamic behavior of concurrent object-oriented systems with Petri nets. Each group of closely related attributes of a concurrent object is modeled by the state of a collection of observable places, and each of its methods by a group of observable transitions. The grouping distinguishes the definition in this paper from others, which makes it easy to work together with the static object models, to reuse the models and to dispel the interference among groups, thus relieving the problem of inheritance anomaly by the possibility of dividing the synchronization code into independent parts. For a formal definition of this behavior subtyping relation, Elementary Net systems, with both S-elements and T-elements labeled, are used. Then it is extended informally to the state based coloured Petri net systems. Finally, the background of the definitions and the future work are presented.
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    Notes on Liveness and Boundedness of Extended Strong Asymmetric Choice Nets Ⅱ
    JIAO Li(焦莉)and LU Weiming(陆维明)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(302KB) ( 1259 )   Chinese Summary
    In this paper, the Extended Strong Asymmetric Choice Nets II (ESACN II), a subclass of Asymmetric Choice Nets (CAN) including Extended Free Choice Nets (EFCN) and Strong Asymmetric Choice Nets II (SACN II), is presented. A necessary and sufficient condition for liveness of ESACN II is proposed. Moreover, a criterion is introduced, which is necessary and sufficient for judgement of liveness and boundedness of ESACN II. Meanwhile a polynomial time algorithm is given to decide liveness and boundedness for ESACN II.
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    Hyper-Distributed Hyper-Parallel Self-Organizing Dynamic Scheduling Based on Solitary Wave
    SHUAI Dianxun(帅典勋),GU Jing(顾静),GU Huiping(顾慧平)and DENG Zhidong(邓志东)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(362KB) ( 1246 )   Chinese Summary
    This paper presents a new soliton approach to hyper-distributed hyper-parallel self-organizing dynamic scheduling for task allocations among rational autonomous agents in a multi-agent system (MAS). This approach can overcome many drawbacks of other mechanisms currently used for coalition formation and cooperation in MAS. The thorny problems, such as overabundant bid, social behaviors, colony intelligence, variable neighbors, and interdependency, can easily be treated by using the proposed approach, whereas they are very difficult for other conventional approaches. The simulation on a distributed transport scheduling system shows the soliton approach featured by hyper-parallelism, effectiveness, openness, dynamic alignment and adaption.
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    Geometric Deformations Based on 3D Volume Morphing
    JIN Xiaogang(金小刚),WAN Huagen(万华根)and PENG Qunsheng(彭群生)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(399KB) ( 2243 )   Chinese Summary
    This paper presents a new geometric deformation method based on 3D volume morphing by using a new concept called directional polar coordinate. The user specifies the source control object and the destination control object which act as the embedded spaces. The source and the destination control objects determine a 3D volume morphing which maps the space enclosed in the source control object to that of the destination control object. By embedding the object to be deformed into the source control object, the 3D volume morphing determines the deformed object automatically without the tiring moving of control points. Experiments show that this deformation model is efficient and intuitive, and it can achieve some deformation effects which are difficult to achieve for traditional methods.
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    An Algorithm for LOD by Merging Near Coplanar Faces Based on Gauss Sphere
    CAO Weiqun(曹卫群),BAO Hujun(鲍虎军)and PENG Qunsheng(彭群生)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(334KB) ( 1668 )   Chinese Summary
    LOD (Level of Detail) models are widely used recently to accelerate the rendering of 3D scenes. An algorithm that creates multiple levels of detail for 3D scene by merging near-coplanar faces is presented in this paper. First a Gauss sphere is defined for the model of scene and it is divided into meshes near-uniformly. Then, the faces of objects are attached to the respective spherical meshes according to their normal direction. If faces attached to the same mesh are connected with each other, they are merged to form a near coplanar patch (Superface). Isolated vertices inside the patch are removed and the patch is retriangulated. To further improve the simplification, vicinity vertices on the boundary of the surface patch are merged. In the algorithm, a planar separate rule planar-enneatree is adopted to set up a hierarchical structure of the Gauss sphere, which is used to support the hierarchical model of the scene (LOD). The experimental result shows that the algorithm can achieve desired simplification effects.
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    Robust Speech Recognition Method Based on Discriminative Evironment Feature Extraction
    HAN Jiqing(韩纪庆)and GAO Wen(高文)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(271KB) ( 1484 )   Chinese Summary
    It is an effective approach to learn the influence of environmental parameters, such as additive noise and channel distortions, from training data for robust speech recognition. Most of the previous methods are based on {maximum likelihood estimation} criterion. However, these methods do not lead to a minimum error rate result. In this paper, a novel discriminative learning method of environmental parameters, which is based on Minimum Classification Error (MCE) criterion, is proposed. In the method, a simple classifier and the Generalized Probabilistic Descent (GPD) algorithm are adopted to iteratively learn the environmental parameters. Consequently, the clean speech features are estimated from the noisy speech features with the estimated environmental parameters, and then the estimations of clean speech features are utilized in the back-end HMM classifier. Experiments show that the best error rate reduction of 32.1% is obtained, tested on a task of 18 isolated confusion Korean words, relative to a conventional HMM system.
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    Study on Distributed Knowledge Information System for Product Design
    ZHOU Shouqin(周受钦),CHIN Kwai Sang(钱桂生),LING Weiqing(凌卫青)and XIE Youbai(谢友柏)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(338KB) ( 1563 )   Chinese Summary
    To overcome the limitations of commercial CAD and handbook form of knowledge expression, the Distributed Knowledge Information System (DKIS) for product design is proposed. The structure of DKIS and the key issues in its implementation are introduced; the method of knowledge store and transfer of DKIS is discussed. The mechanism of knowledge representation, acquisition and utilization, based on Internet network, is achieved. Based on the concept of function driven, integrated Artificial Neural Networks and Active Server Pages techniques, transplanting the trained ANN into DKIS system, a new method for retrieving knowledge in DKIS over Internet is achieved. Finally, a prototype of DKIS is developed to demonstrate the feasibility of the structure and constructional method of DKIS. The work provides a scheme for speed knowledge acquisition and shortens the cycle of product development.
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    Fault-Tlerant Tree-Based Multicasting in Mesh Multicomputers
    WU Jie(吴杰)and CHEN Xiao
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(458KB) ( 1265 )   Chinese Summary
    We propose a fault-tolerant tree-based multicast algorithm for 2-dimensional (2-D) meshes based on the concept of the extended safety level which is a vector associated with each node to capture fault information in the neighborhood. In this approach each destination is reached through a minimum number of hops. In order to minimize the total number of traffic steps, three heuristic strategies are proposed. This approach can be easily implemented by pipelined circuit switching (PCS). A simulation study is conducted to measure the total number of traffic steps under different strategies. Our approach is the first attempt to address the fault-tolerant tree-based multicast problem in 2-D meshes based on limited global information with a simple model and succinct information.
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    Node Grouping in System-Level Fault Diagnosis
    ZHANG Dafang(张大方),XIE Gaogang(谢高岗)and MIN Yinhua(闵应骅)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(280KB) ( 1617 )   Chinese Summary
    With the popularization of network applications and multiprocessor systems, dependability of systems has drawn considerable attention. This paper presents a new technique of node grouping for system-level fault diagnosis to simplify the complexity of large system diagnosis. The technique transforms a complicated system to a group network, where each group may consist of many nodes that are either fault-free or faulty. It is proven that the transformation leads to a unique group network to ease system diagnosis. Then it studies systematically one-step t-faults diagnosis problem based on node grouping by means of the concept of independent point sets and gives a simple sufficient and necessary condition. The paper presents a diagnosis procedure for t-diagnosable systems. Furthermore, an efficient probabilistic diagnosis algorithm for practical applications is proposed based on the belief that most of the nodes in a system are fault-free. The result of software simulation shows that the probabilistic diagnosis provides high probability of correct diagnosis and low diagnosis cost, and is suitable for systems of any kind of topology.
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    Efficient Indirect All-to-All Personalized Communication on Rings and 2-D Tori
    GU Naijie(顾乃杰)
    Journal of Computer Science and Technology, 2001, 16 (5): 0-0. 
    Abstract   PDF(225KB) ( 1307 )   Chinese Summary
    All-to-All personalized communication is a basic communication operation in a parallel computing environment. There are a lot of results appearing in literature. All these communication algorithms can be divided into two kinds: direct communication algorithm and indirect communication algorithm. The optimal direct all-to-all communication algorithm on rings and 2-D tori does exist. But, for indirect all-to-all communication algorithms, there is a gap between the time complexity of the already existing algorithm and the lower bound. In this paper an efficient indirect algorithm for all-to-all communication on rings and 2-D square tori with bidirection channels is presented. The algorithms is faster than any previous indirect algorithms. The main items of the time complexity of the algorithm is p^2/8 and p^3/2/8 on rings and 2-D tori respectively, both reaching the theoretical lower bound, where p is the number of processors.
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ISSN 1000-9000(Print)

CN 11-2296/TP

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Journal of Computer Science and Technology
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