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Reliability-aware automatic composition approach for web services

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science china(Information sciences) 2012年第4期55卷 921-937页

作者： LI Mu 1,2.LI Bo 1,2.& HUAI JinPeng 1,2.1 State Key Laboratory of Software Development Environment,beihang university,beijing 100191,{2. 2.School of computer science and engineering,beihang university,beijing 100191,{2. 1. State Key Laboratory of Software Development Environment Beihang University Beijing 100191 China2. School of Computer Science and Engineering Beihang University Beijing 100191 China

In this paper,we study the reliability-aware synthesis problem for composing available services automatically and guaranteeing that the composed result satisfies the specification,such as temporal constraints of functionality and reliability,centered on a synthesis model for mediator of web services composition (CSM).This approach focuses on handling attributes and state relations,and permitting users and services to operate over them,i.e.,read /write their data values and compare them according to a dense state *** show that the reliability-aware synthesis problem for the specification is EXPTIME-complete and we give an exponential-time algorithm (CSM-NSA) which for a given formula ψ and a synthesis model,synthesizes available services in the library satisfying ψ over the synthesis model (if they exist) or responds with "not satisfiable" (otherwise).The specification ψ is a fragment of PCTL (probabilistic computation tree logic),obtained from "ordinary" CTL (computation tree logic) by replacing the EX,AX,EU and AU operation with their quantitative counterparts X >p,X =1,U >p,and U =1,*** opposed to NSA,we provide a more effective algorithm to replace the NSA algorithm called CSM-HSA (heuristic synthesis algorithm).Though HSA is an incomplete algorithm,the answer is *** experiments show that the HSA algorithm solves the problem of reliability-aware service synthesis effectively and efficiently.

关键词： reliability web services synthesis problem synthesis model heuristic algorithm

Radiance-based color calibration for image-based modeling with multiple cameras

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science china(Information sciences) 2012年第7期55卷 1509-1519页

作者： ZHAO Xu 1,2.,ZHOU Zhong 1,2.& WU Wei 1,2.1 State Key Laboratory of Virtual Reality Technology and Systems,beihang university,beijing 100191,{2. 2.School of computer science and engineering,beihang university,beijing 100191,{2. 1. State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 China2. School of Computer Science and Engineering Beihang University Beijing 100191 China

Photo-consistency estimation is an important part for many image-based modeling *** paper presents a novel radiance-based color calibration method to reduce the uncertainty of photo-consistency estimation across multiple *** idea behind our method is to convert colors into a uniform radiometric color space in which multiple image data are *** results demonstrate that our method can achieve comparable color calibration effect without adjusting camera parameters and is more robust than other existing ***,we obtain an auto-determined threshold for photo-consistency check,which will lead to a better performance than existing photo-consistency based reconstruction algorithms.

关键词： color calibration photo-consistency estimation multi-camera system image-based modeling

A spatio-velocity model based semantic event detection algorithm for traffic surveillance video

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science china(Technological sciences) 2010年第S1期53卷 120-125页

作者： SHENG Hao 1,ZHAO HuiJie 1,HUANG Jian 2.& LI Na 1 1 School of Instrument science and Opto-Electro engineering,{2.,beijing 100191,china 2.School of Software,{2.,beijing 100191,china 1. School of Instrument science and Opto-Electro engineering Beijing University Beijing 100191 China 2. School of Software Beijing University Beijing 100191 China

Detection of vehicle events is a research hotspot in digital *** this paper,an approach is proposed to detect vehicle events with semantic analysis of traffic surveillance video using spatio-velocity statistic *** approach includes two successive phases:trajectory clustering and semantic events *** trajectory clustering,a statistic model of vehicle trajectories are presented,for which a spatio-velocity model is trained by analyzing the trajectories of moving vehicles in the *** on the trajectory,which represents both the position of the vehicle and its instantaneous velocity,a trajectory similarity measure is ***,an improved hierarchical clustering algorithm is adopted to cluster the trajectories according to different spatial and velocity *** each cluster,trajectories that are spatially close have similar velocities of motion and represent one type of activity *** the semantic events detection phase,statistic models of semantic regions in the scene are generated by estimating the probability density and velocity distributions of each type of activity ***,semantic events are detected by the proposed spatio-velocity statistic *** paper also presents experiments using real video sequence to verify the effectiveness of the proposed method.

关键词： trajectory clustering spatio-velocity statistic model event detection digital traffic

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Complexity of synthesis of composite service with correctness guarantee

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science china(Information sciences) 2012年第3期55卷 638-649页

作者： DENG Ting1,2., HUAI JinPeng1,3 & WO TianYu1,3 1State Key Laboratory of Software Development Environment, beihang university beijing 100191, {2. 2.chool of Mathematics and System science, beihang university, beijing 100191, {2. 3School of computer science and engineering, beihang university, beijing 100191, {2. 1. State Key Laboratory of Software Development Environment Beihang University Beijing 100191 China2. School of Mathematics and System Science Beihang University Beijing 100191 China3. School of Computer Science and Engineering Beihang University Beijing 100191 China

How to compose existing web services automatically and to guarantee the correctness of the design (e.g. temporal constraints specified by temporal logic LTL, CTL or CTL*) is an important and challenging problem in web services. Most existing approaches use the process in conventional software development of design, verification, analysis and correction to guarantee the correctness of composite services, which makes the composition process both complex and time-consuming. In this paper, we focus on the synthesis problem of composite service; that is, for a given set of services and correctness constraint specified by CTL or CTL* formula, a composite service is automatically constructed which guarantees that the correctness is ensured. We prove that the synthesis problem for CTL and CTL* are complete for EXPTIME and 2.XPTIME, respectively. Moreover, for the case of synthesis failure, we discuss the problem of how to disable outputs of environment (i.e. users or services) reasonably to make synthesis successful, which are also proved complete for EXPTIME and 2.XPTIME for CTL and CTL*, respectively.

关键词： business protocol composite service synthesis environment branching temporal logic

Evolution and stability of Linux kernels based on complex networks

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science china(Information sciences) 2012年第9期55卷 1972-1982页

作者： WANG Lei,WANG Zheng,YANG Chen & ZHANG Li School of computer science and {2.,beihang university,beijing 100191,china 1. School of computer science and {2. Beihang University Beijing 100191 China

This paper presents a novel method to study Linux kernel evolution using complex *** investigated the node degree distribution and average path length of the call graphs corresponding to the kernel modules of 2.3 different versions(V1.1.0 to V2.4.35),we found that the call graphs are scale-free and smallworld *** on the relationship between average path length and nodes,we propose a method to find unusual points during Linux kernel evolution using the slope of the average path *** the unusual points we identify major structural changes in kernel modules.A stability coefficient is also proposed to describe quantitatively the stability of kernel modules during ***,we verify our result through Vasa’s metrics method.

关键词： complex networks operating system scale-free networks small-world networks average path length

Logical verification of scientific discovery

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science china(Information sciences) 2010年第4期53卷 677-684页

作者： LI Wei State Key Laboratory of Software Development Environment, School of computer science and {2., beihang university, beijing 100191, china 1. State Key Laboratory of Software Development Environment School of Computer Science and Engineering Beihang University Beijing 100191 China

This paper shows that the discovery processes of Einstein’s special theory of relativity and Darwin’s theory of evolution of species can be formally verified by R-calculus which is a logical inference system. The aim of R-calculus is to delete the principles of scientific theories which contradict empirical evidence. The paper shows that the special theory of relativity is the only and correct choice for physics to meet the experimental evidence given at the time. As far as the biology of Darwin’s time is concerned, however, the R-calculus has derived three logically correct but different theories, which are all consistent with the empirical evidence provided by Darwin and his principle of natural selection. Darwin’s theory of evolution matches one of the three theories derived by R-calculus. This theory has a logical consequence that is "each species has been independently created is erroneous". But the other two theories support the negation of the above statement. The existence of the other two theories may be a reason of the controversies over Darwin’s theory.

关键词： R-calculus theory of relativity theory of evolution

Gray physical interference model based link scheduling algorithms

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science china(Information sciences) 2012年第6期55卷 1337-1350页

作者： SU JinZhao 1,2.CAO Jing 1,2.& WU Wei 1,2.1 State Key Laboratory of Virtual Reality and Systems,beijing 100191,china 2.School of {2. science and engineering,beihang university,beijing 100191,china 1. State Key Laboratory of Virtual Reality and Systems Beijing 100191 China2. School of Computer Science and Engineering Beihang University Beijing 100191 China

To improve the concurrent data transmission capability of wireless multi-hop networks,this paper proposes adopting a gray physical interference model instead of using the threshold physical interference *** model allows non-ideal links to be involved in scheduling,under the premise of not affecting the quality of existing transmission *** addition,we design two greedy algorithms to schedule more links with SINR values located in the transition *** results show that a gray physical interference model is more accurate than a threshold physical interference one,the concurrent transmission capability of a network based on the gray physical interference model is significantly increased,and network throughput is increased by 2.%.

关键词： gray physical interference model threshold physical interference model link scheduling concurrent transmission TDMA

Preconditioned pseudo-compressibility methods for incompressible Navier-Stokes equations

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中国科学：物理学、力学、天文学英文版 2010年第11期53卷 2090-2102页

作者： QIAN ZhanSen ,ZHANG JingBai & LI ChunXuan School of Aeronautics science and engineering,{2.,beijing 100191,china 1. School of Aeronautics science and engineering Beihang University Beijing 100191 China

This paper investigates the pseudo-compressibility method for the incompressible Navier-Stokes equations and the preconditioning technique for accelerating the time marching for stiff hyperbolic equations,and derives and presents the eigenvalues and eigenvectors of the Jacobian matrix of the preconditioned pseudo-compressible Navier-Stokes equations in generally cur-vilinear *** on the finite difference discretization the cored for efficiently solving incompressible flows numerically is *** reliability of the procedures is demonstrated by the application to the inviscid flow past a circular cylinder,the laminar flow over a flat plate,and steady low Reynolds number viscous incompressible flows past a circular *** is found that the solutions to the present algorithm are in good agreement with the exact solutions or experimental *** effects of the pseudo-compressibility factor and the parameter brought by preconditioning in convergence characteristics of the solution are investigated *** results show that the upwind Roe’s scheme is superior to the second order central scheme,that the convergence rate of the pseudo-compressibility method can be effectively improved by preconditioning and that the self-adaptive pseudo-compressibility factor can modify the numerical convergence rate significantly compared to the constant form,without doing artificial tuning depending on the specific flow *** validation is also performed by numerical simulations of unsteady low Reynolds number viscous incompressible flows past a circular *** results are also found in good agreement with the existing numerical results or experimental data.

关键词： pseudo-compressibility method preconditioning upwind scheme incompressible flow Navier-Stokes equations

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Displacement residual based DDM matching algorithm

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science china(Information sciences) 2012年第9期55卷 2090-2101页

作者： ZHANG Lin 1,2.ZHOU Zhong 1,2.LIU Lin 1,2.& WU Wei 1,2.1 State Key Laboratory of Virtual Reality Technology and Systems,beihang university,beijing 100191,{2. 2.School of computer science and engineering,beihang university,beijing 100191,{2. 1. State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 China2. School of Computer Science and Engineering Beihang University Beijing 100191 China

High level architecture(HLA) is the prevailing standard for modeling and *** data distribution management(DDM) service of HLA is defined for reducing the delivery of irrelevant *** key in DDM implementation is the region overlap computation,*** matching between update and subscription *** algorithms usually make a compromise between region fidelity and network *** paper takes both the matching algorithm efficiency and bandwidth cost into *** main contributions are:1) illustrating the relationship between region changes and overlap changes,as helps reduce the number of region matching and then improves the total matching efficiency;2. classifying region updates into two types of data expression,snapshot and *** network traffic will be reduced by transmitting only residual data instead of full region representations ***,a region matching algorithm called displacement residual-based DDM matching(DRBM) is proposed in the *** analysis,algorithm implementation and experiment evaluation are *** results show that DRBM provides better matching performance and significant network payload reductions especially when there is a large number of changing regions.

关键词： distributed simulation high level architecture data distribution management region snapshot region residual