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CN 11-2296/TP
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  • Table of Content
      15 November 2001, Volume 16 Issue 6 Previous Issue    Next Issue
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    BCL-3:A High Performance Basic Communication Protocol for Commodity Superserver DAWNING-3000
    MA Jie(马捷),HE Jin(贺劲),MENG Dan(孟丹)and LI Guojie(李国杰)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    This paper introduces the design and implementation of BCL-3, a high performance low-level communication software running on a cluster of SMPs (CLUMPS) called DAWNING-3000. BCL-3 provides flexible and sufficient functionality to fulfill the communication requirements of fundamental system software developed for DAWNING-3000 while guaranteeing security, scalability, and reliability. Important features of BCL-3 are presented in the paper, including special support for SMP and heterogeneous network environment, semi-user-level communication, reliable and ordered data transfer and scalable flow control. The performance evaluation of BCL-3 over Myrinet is also given.
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    oodOPT:A Semantics-Based Concurrency Control Framework for Fully-Replicated Architecture
    YANG Guangxin(杨光信)and SHI Meilin(史美林)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    Concurrency control has always been one of the most important issues in the design of synchronous groupware systems with fully-replicated architecture. An ideal strategy should be able to support natural and flexible human-to-computer and human-to-human interactions while maintaining the consistency of the system. This paper summarizes previous researches on this topic and points out the deficiencies of the existing results. A novel semantics-based concurrency control framework, oodOPT, is proposed. The main idea of the framework is to resolve conflicts by utilizing semantics of the operations and the accessed data objects. With this approach, complexities in concurrency control are shifted completely from application developers to the framework. Conflicts among operations on objects with different semantics and the strategies resolving these conflicts are analyzed. After describing the algorithm in full detail, the discussion ends up with a comparison with other related work and some considerations for open problems.
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    Active Network Supports for Mobile IP
    LU Yueming(陆月明),QIAN Depei(钱德沛),XU Bin(徐 斌)and WANG Lei(王磊)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    The basic mobile IP protocol is difficult to implement on the traditional IP network and not flexible and efficient under certain conditions. For example, firewalls or boundary routers may drop packets sent by mobile nodes for security reasons. Traditional networking devices such as routers cannot dynamically load and unload extended services to achieve different qualities of services. In this paper, a new scheme of using the active network to support the mobile IP is presented. The Softnet, a prototype of active networks based on mobile agents, is introduced. The active network is characterized by the programmability of its intermediate nodes and therefore presents dynamic and flexible behaviors. Special services can be dynamically deployed onto the active nodes in the Softnet. This property is definitely required in implementing the mobile IP protocols. The Softnet supports not only the basic mobile IP protocol but also other extended mobile IP protocols. Virtual networks for mobile IP services are dynamically formed by mobile agents in the Softnet to provide different qualities of services.
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    CIM Algorithm for Approximating Three-Dimensional Polygonal Curves
    YONG Junhai(雍俊海),HU Shimin(胡事民)and SUN Jiaguang(孙家广)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    The polygonal approximation problem is a primary problem in computer graphics, pattern recognition, CAD/CAM, etc. In R^2, the cone intersection method (CIM) is one of the most efficient algorithms for approximating polygonal curves. With CIM Eu and Toussaint, by imposing an additional constraint and changing the given error criteria, resolve the three-dimensional weighted minimum number polygonal approximation problem with the parallel-strip error criterion (PS-WMN) under L_2 norm. In this paper, without any additional constraint and change of the error criteria, a CIM solution to the same problem with the line segment error criterion (LS-WMN) is presented, which is more frequently encountered than the PS-WMN is. Its time complexity is O(n^3), and the space complexity is O(n^2). An approximation algorithm is also presented, which takes O(n^2) time and O(n) space. Results of some examples are given to illustrate the efficiency of these algorithms.
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    Extracting Local Schema from Semistructured Data Based on Graph-Oriented Semantic Model
    WANG Tenjiao(王腾蛟),TANG Shiwei(唐世渭),YANG Dongqing(杨冬青),LIU Yunfeng(刘云峰)and LIN Bin(林斌)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    Many modern applications (e-commerce, digital library, etc.) require integrated access to various information sources (from traditional RDBMS to semistructured Web repositories). Extracting schema from semistructured data is a prerequisite to integrate heterogeneous information sources. The traditional method that extracts global schema may require time (and space) to increase exponentially with the number of objects and edges in the source. A new method is presented in this paper, which is about extracting local schema. In this method, the algorithm controls the scale of extracting schema within the "schema diameter'' by examining the semantic distance of the target set and using the Hash class and its path distance operation. This method is very efficient for restraining schema from expanding. The prototype validates the new approach.
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    A New Color Constancy Model for Machine Vision
    TAO Linmi(陶霖密)and XU Guangyou
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    Both physiological and psychological evidences suggest that the human visual system analyze images in neural subsystems tuned to different attributes of the stimulus. Color module and lightness module are such subsystems. Under this general result, a new physical model of trichromatic system has been developed to deal with the color constancy of computer vision. A normal color image is split into two images: the gray scale image and the equal lightness color image for the two modules. Relatively, a two-dimensional descriptor is applied to describe the property of surface reflectance in the equal lightness color image. This description of surface spectral reflectance has the property of color constancy. Image segmentation experiments based on color property of object show that the presented model is effective.
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    Extracting Objects from Ada83 Programs:A Case Study
    XU Baowen(徐宝文)and ZHOU Yuming(周毓明)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    Reengineering legacy systems written in conventional procedural languages to equivalent OO systems makes software more maintainable and reliable. This paper proposes a method for extracting objects from legacy Ada83 systems using module features. First, metrics are developed to measure module cohesion. Then, effects on cohesion from changing module components are analyzed and rules about how to extract inheritance relations among objects are given. At the end of this paper, an object-extracting algorithm using module features is proposed.
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    Domains via Graphs
    ZHANG Guoqiang(张国强)and CHEN Yixiang(陈仪香)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    This paper provides a concrete and simple introduction to two pillars of domain theory: (1) solving recursive domain equations, and (2) universal and saturated domains. Our exposition combines Larsen and Winskel's idea on solving domain equations using information systems with Girard's idea of stable domain theory in the form of coherence spaces, or graphs. Detailed constructions are given for universal and even homogeneous objects in two categories of graphs: one representing binary complete, prime algebraic domains with complete primes covering the bottom; the other representing omega-algebraic, prime algebraic lattices. The back-and-forth argument in model theory helps to enlighten the constructions.
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    Comparion of Different Implementations of MFCC
    ZHENG Fang(郑方),ZHANG Guoliang(张国亮)and SONG Zhanjiang(宋战江)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    Abstract   PDF(310KB) ( 4165 )   Chinese Summary
    The performance of the Mel-Frequency Cepstrum Coefficients (MFCC) may be affected by (1) the number of filters, (2) the shape of filters, (3) the way in which filters are spaced, and (4) the way in which the power spectrum is warped. In this paper, several comparison experiments are done to find a best implementation. The traditional MFCC calculation excludes the 0th coefficient for the reason that it is regarded as somewhat unreliable. According to the analysis and experiments, the authors find that it can be regarded as the generalized frequency band energy (FBE) and is hence useful, which results in the FBE-MFCC. The authors also propose a better analysis, namely the auto-regressive analysis, on the frame energy, which outperforms its 1st and/or 2nd order differential derivatives. Experiments with the "863" Speech Database show that, compared with the traditional MFCC with its corresponding auto-regressive analysis coefficients, the FBE-MFCC and the frame energy with their corresponding auto-regressive analysis coefficients form the best combination, reducing the Chinese syllable error rate (CSER) by about 10%, while the FBE-MFCC with the corresponding auto-regressive analysis coefficients reduces CSER by 2.5%. Comparison experiments are also done with a quite casual Chinese speech database, named Chinese Annotated Spontaneous Speech (CASS) corpus. The FBE-MFCC can reduce the error rate by about 2.9% on an average.
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    Constraint-Preserving Architecture Transformations:A Graph Rewriting Appraoch
    YUAN Chun(袁春)and CHEN Yiyun(陈意云)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    Abstract   PDF(251KB) ( 943 )   Chinese Summary
    Architecture transformations are frequently performed during software design and maintenance. However this activity is not well supported at a sufficiently abstract level. In this paper, the authors characterize architecture transformations using graph rewriting rules, where architectures are represented in graph notations. Architectures are usually required to satisfy certain constraints during evolution. Therefore a way is presented to construct the sufficient and necessary condition for a transformation to preserve a constraint. The condition can be verified before the application of the transformation. Validated transformations are guaranteed not to violate corresponding constraints whenever applied.
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    A Sufficient Condition for a Wire-Frame Representing a Solid Modeling Uniquely
    WANG Jiaye(汪嘉业),CHEN Hui(陈 辉)and WANG Wenping(王文平)
    Journal of Computer Science and Technology, 2001, 16 (6): 0-0. 
    Abstract   PDF(83KB) ( 894 )   Chinese Summary
    Generally speaking, it is impossible for a wire-frame to define a 3D object uniquely. But wire-frame as a graphics medium is still applied in some industrial areas. A sufficient condition is presented in this paper. If this condition is satisfied by a wire-frame, then the wire-frame can represent a 3D object uniquely. The result is applied to manufacturing of progressive stripe.
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    Reduction Algorithms Based on Discernibility Matrix:The Ordered Attributes Method
    WANG Jue(王珏)and WANG Ju(王驹)
    Journal of Computer Science and Technology, 2001, 16 (6): 489-504. 
    Abstract   PDF(397KB) ( 3798 )   Chinese Summary
    In this paper, we present reduction algorithms based on the principle of Skowron's discernibility matrix --- the ordered attributes method. The completeness of the algorithms for Pawlak reduct and the uniqueness for a given order of the attributes are proved. Since a discernibility matrix requires the size of the memory of |U|^2, U is a universe of objects, it would be impossible to apply these algorithms directly to a massive object set. In order to solve the problem, a so-called quasi-discernibility matrix and two reduction algorithms are proposed. Although the proposed algorithms are incomplete for Pawlak reduct, their optimal paradigms ensure the completeness as long as they satisfy some conditions. Finally, we consider the problem on the reduction of distributive object sets.
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ISSN 1000-9000(Print)

CN 11-2296/TP

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