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An algorithm to compute maximal contractions for Horn clauses

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Science china.information Sciences) 2011年第2期54卷 244-257页

作者： LUO Jie & LI Wei State Key Laboratory of Software Development Environment, School of computer Science and technology, Beihang university, beijing 100191, china State Key Laboratory of Software Development Environment School of Computer Science and Technology Beihang University

In the theory of belief revision, the computation of all maximal subsets (maximal contractions) of a formula set with respect to a set of facts is one of the key problems. In this paper, we try to solve this problem by studying the algorithm to compute all maximal contractions for Horn clauses. First, we point out and prove the conversion relationship between minimal inconsistent subsets of union of the formula set and the set of facts and maximal contractions of the formula set with respect to the set of facts. Second, we prove a necessary condition of a set of Horn clauses to be minimal inconsistent. Then, based on these two conclusions, we propose an interactive algorithm to enumerate all minimal inconsistent subsets of a given set of Horn clauses and a second algorithm to compute maximal contractions from these minimal inconsistent subsets. Finally, we proposed an interactive algorithm to compute maximal contractions for Horn clauses by composing the above two algorithms.

关键词： maximal contraction minimal inconsistent set minimal subtraction Horn clause

Theoretical research progress in new-generation Internet architecture

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Science in china.Series F) 2008年第11期51卷 1634-1660页

作者： WU JianPing1,2,3,LIU Ying2,3 & WU Qian2,3 1 Department of computer Science,Tsinghua university,beijing 100084,china.2 Network Research Center,Tsinghua university,beijing 100084,china.3 Tsinghua National Laboratory for information Science and technology(TNList) ,beijing 100084,china Department of computer Science Tsinghua University Network Research Center Tsinghua University Tsinghua National Laboratory for information Science and technology (TNList)

Internet has become the most important information infrastructure supporting modern socio-economic development, social progress and technological Innovation. Invented 30 years ago, today Internet is facing increasingly severe technical challenges. This paper introduces the progress of the major international newgeneration Internet research plans; analyzes its basic characteristics and the principal contradictions during the development; detsiledly introduces the research carried out by 973 Project ＂Research of Future Internet Architecture＂ on the key scientific issues of new-generation Internet architecture and its latest research results; and looks to the future of the research-focus faced with the new situations of the basic research of new-generation Internet architecture as well as the new demands of innovative applications on Internet architecture.

关键词： new-generation Internet network architecture multi-dimension scalability

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A TTCN-3-based protocol testing system and its extension

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Science in china.Series F) 2008年第11期51卷 1703-1722页

作者： YIN Xia1,3,WANG ZhiLiang2,3,JING ChuanMing1,3 & SHI XinGang2,3 1 Department of computer Science and technology,Tsinghua university,beijing 100084,china.2 Network Research Center,Tsinghua university,beijing 100084,china.3 Tsinghua National Laboratory for information Science and technology(TNList) ,beijing 100084,china Department of computer Science and technology Tsinghua University Network Research Center Tsinghua University Tsinghua National Laboratory for information Science and technology (TNList)

The protocol testing technology used in the next generation Internet should satisfy some new challenges and requirements. This paper focuses on the test suite description and test implementation techniques. TTCN-3 is chosen as the test suite description language and extended in both syntax and semantics to satisfy the requirements of protocol robustness testing. PITSv3, a protocol integrated testing system based on TTCN-3, is developed, and the extensions for robustness testing are implemented. Finally, two practical test applications are presented.

关键词： protocol testing TTCN-3 PITSv3 robustness testing

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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 engineering,Beihang university,beijing 100191,china School of computer Science and engineering Beihang University Beijing 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 223 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

Fuzzy dynamic characteristic modeling and adaptive control of nonlinear systems and its application to hypersonic vehicles

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Science china.information Sciences) 2011年第3期54卷 460-468页

作者： LI HongBo , SUN ZengQi, MIN HaiBo & DENG JianQiu Department of computer Science and technology, Tsinghua university, beijing 100084, china Department of computer Science and technology Tsinghua University

In this paper, a fuzzy dynamic characteristic modeling and adaptive control method is proposed for a class of nonlinear systems. By employing fuzzy dynamic characteristic model, the controlled plant is described as a slowly time-varying fuzzy system, wherein the parameters are estimated online by using recursive Least-Squares algorithm. Under this framework, a fuzzy adaptive controller is constructed, and the stability condition of the closed-loop system is also derived. The main advantage of the proposed method lies in no requirement for the prior knowledge of system model and less parameters to tune, which allows engineers to operate it in a simple, straightforward manner. The proposed method is applied to the control of hypersonic vehicle, and simulation results are given to demonstrate the effectiveness of the obtained results.

关键词： fuzzy control dynamic characteristic model adaptive control hypersonic vehicle

(G′/G)展开法在高维非线性物理方程中的新应用

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物理学报 2009年第11期58卷 7402-7409页

作者：马玉兰李帮庆孙践知北京工商大学计算机与信息工程学院北京100048

将(G′/G)展开首次法扩展到构造高维非线性物理方程的精确非行波通解、研究解的特殊孤子结构和混沌行为.作为(G′/G)展开法的新应用,获到了(3+1)维非线性Burgers系统的新非行波通解,对通解中的任意函数进行适当的设置,探讨了特殊孤子结... 详细信息

将(G′/G)展开首次法扩展到构造高维非线性物理方程的精确非行波通解、研究解的特殊孤子结构和混沌行为.作为(G′/G)展开法的新应用,获到了(3+1)维非线性Burgers系统的新非行波通解,对通解中的任意函数进行适当的设置,探讨了特殊孤子结构的激发和演化、解的混沌行为和演化.

关键词： (G′/G)展开法 Burgers系统孤子结构混沌行为

维普期刊数据库

More efficient automatic repair of large-scale programs using weak recompilation

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Science china.information Sciences) 2012年第12期55卷 2785-2799页

作者： QI YuHua 1,MAO XiaoGuang 1,WEN YanJun 1,DAI ZiYing 1 & GU Bin 2 1 School of computer,National university of Defense technology,Changsha 410073,china.2 beijing Institute of Control engineering,beijing 100190,china School of computer National University of Defense Technology Changsha China beijing Institute of Control engineering Beijing China

Automatically repairing a bug can be a time-consuming process especially for large-scale programs owing to the significant amount of time spent recompiling and reinstalling the patched *** reduce this time overhead and speed up the repair process,in this paper we present a recompilation technique called weak *** weak recompilation,we assume that a program consists of a set of components,and for each candidate patch only the altered components are recompiled to a shared *** original program is then dynamically updated by a function indirection *** advantage of weak recompilation is that redundant recompilation cost can be avoided,and while the reinstallation cost is completely eliminated as the original executable program is not modified at *** maximum applicability of weak recompilation we created WAutoRepair,a scalable system for fixing bugs with high efficiency in large-scale C *** experiments on real bugs in widely used programs show that our repair system significantly outperforms Genprog,a wellknown approach to automatic program *** the wireshark program containing over 2 million lines of code,WAutoRepair is over 128 times faster in terms of recompilation cost than Genprog.

关键词： weak recompilation efficiency automated program repair automated debugging experiment

Adaptive neural control based on HGO for hypersonic flight vehicles

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Science china.information Sciences) 2011年第3期54卷 511-520页

作者： XU Bin 1,2 , GAO DaoXiang 3 & WANG ShiXing 1 1 Department of computer Science and technology, Tsinghua university, beijing 100084, china.2 Autonomous System Lab, ETH Zurich Zurich 8092, Switzerland 3 School of technology, beijing Forestry university, beijing 100083, china Department of computer Science and technology Tsinghua University Autonomous System Lab ETH Zurich School of technology Beijing Forestry University

This paper describes the design of adaptive neural controller for the longitudinal dynamics of a generic hypersonic flight vehicle (HFV) which are decomposed into two functional systems, namely the altitude subsystem and the velocity subsystem. For each subsystem, one adaptive neural controller is investigated based on the normal output-feedback formulation. For the altitude subsystem, the high gain observer (HGO) is taken to estimate the unknown newly defined states. Only one neural network (NN) is employed to approximate the lumped uncertain system nonlinearity during the controller design which is considerably simpler than the ones based on back-stepping scheme with the strict-feedback form. The Lyapunov stability of the NN weights and filtered tracking error are guaranteed in the semiglobal sense. Numerical simulation study of step response demonstrates the effectiveness of the proposed strategy in spite of system uncertainty.

关键词： adaptive neural control hypersonic flight vehicle high gain observer output-feedback

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,china.2 School of computer Science and engineering,Beihang university,beijing 100191,china State Key Laboratory of Virtual Reality technology and Systems Beihang University Beijing China School of computer Science and engineering Beihang University Beijing 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