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A note on the tree decompositions of graphs

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chinese Science Bulletin 1997年第23期42卷 1948-1952页

作者： SHI MinyongInstitute of software, chinese academy of sciences, beijing 100080,{3. Institute of software Chinese Academy of Sciences Beijing China

IN this note all graphs are undirected, finite and simple. For a subgraph H of G,ε（H） andμ（H） denote the number of edges in H and the number of cycles in H respectively. H[X]denotes the subgraph of H induced by X. Given two disjoint subsets X and Y of V（G）, wewrite EG（X, Y）={xy∈E（G）|x∈X, y∈Y}. Sometimes EG（H, Y）=EG（V（H）,Y） is used for a subgraph H of G-Y. If T is a tree of G and e=uv∈G-E（T）with{u,v}V（T）, then T + e contains a unique cycle, denoted by C（T, e）.A tree-decomposition {T1, T2, …, Tk} of a graph G is a partition of E （G）, say,E（G）=E1 U E2 U…U Ek, such that for each i with 1≤i≤k, Ti=G[Ei] is a tree.

关键词： tree decomposition singular vertex maximal planar bipartite graph.

Integrated precise orbit determination of Shenzhou IV unmanned spacecraft

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Science china(Technological sciences) 2004年第5期47卷 518-525页

作者： L Congmin1,2, GU Yidong3. LIN Baojun3.& GUO Jiong3.1. Center for Space Science and Applied Research, chinese academy of sciences, beijing 100080, china 2. Graduate School of the chinese academy of sciences, beijing 10003., china 3. General Establishment of Space Science and Application, chinese academy of sciences, beijing 100080, china Correspondence should be addressed to L Congmin 1. Center for Space Science and Applied Research Chinese Academy of Sciences 100080 Beijing China 2. Graduate School of the chinese academy of sciences 100039 Beijing China 3. General Establishment of Space Science and Application Chinese Academy of Sciences 100080 Beijing China

Considering the characteristic orbit of Shenzhou IV spacecraft and the advantages and disadvantages of several types of domestic orbit measurements, a scheme of IPOD is determined, which uses GPS, SLR and USB observation data jointly plus precise ionosphere corrections to GPS observation data. IPOD system and mathematic models of OD are introduced. The results of different joint OD are analyzed using true observation data, and show that radial accuracy is better than 2 m.

关键词： Shenzhou IV unmanned spacecraft integrated precise orbit determination GPS SLR USB.

Formal analysis and design of multi-party fair exchange protocols

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Science in china(Series F) 2006年第2期49卷 155-174页

作者： QING Sihan1,2,3.& LI Gaicheng1,3.1. Engineering Research Center for Information Security Technology, Institute of software, chinese academy of sciences, beijing 100080,{3. 2. beijing Zhongke Ansheng Corporation of Information Technology, beijing 100080,{3. 3. Graduate School of the chinese academy of sciences, beijing 10003.,{3. 1. Engineering Research Center for Information Security Technology Institute of Software Chinese Academy of Sciences Beijing 100080 China 2. beijing Zhongke Ansheng Corporation of Information Technology Beijing 100080 China 3. Graduate School of the chinese academy of sciences Beijing 100039 China

Based on the origin of message items and channel combination between transacting parties, and events and relations among events, this paper presents a concise, precise, and hierarchical model for general fair exchange protocols, formally specifies various security requirements which are able to reflect inherent requirements for fair exchange protocols more rigorously, and partition these security requirements with fine granularity. This work helps analyze, debug, and design multi-party fair exchange protocols more effectively and elaborately,

关键词： fair exchange logical protocol formal model security requirement.

A mixed method for measuring low-frequency acoustic properties of macromolecular materials

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Science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 729-739页

作者： LIU Hongwei1,YAO Lei1,3.ZHAO Hong1,3.ZHANG Jichuan2,3.& XUE Zhaohong2 1. National Key Laboratory of Acoustics,Institute of Acoustics,chinese academy of sciences,{3. 100080,china 2. Institute of Chemistry,chinese academy of sciences,{3. 100080,china 3. Graduate University of chinese academy of sciences,{3. 100049,china National Key Laboratory of Acoustics Institute of Acoustics Chinese Academy of Sciences Beijing 100080 China Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China Graduate University of chinese academy of sciences Beijing 100049 China

A mixed method for measuring low-frequency acoustic properties of macro-molecular materials is presented. The dynamic mechanical parameters of materials are first measured by using Dynamic Mechanical Thermal Apparatus(DMTA) at low frequen-cies,usually less than 100 Hz; then based on the Principles of Time-Temperature Super-position (TTS),these parameters are extended to the frequency range that acousticians are concerned about,usually from hundreds to thousands of hertz; finally the extended dynamic mechanical parameters are transformed into acoustic parameters with the help of acoustic measurement and inverse analysis. To test the feasibility and accuracy,we measure a kind of rubber sample in DMTA and acquire the basic acoustic parameters of the sample by using this method. While applying the basic parameters to calculating characteristics of the sample in acoustic pipe,a reasonable agreement of sound absorp-tion coefficients is obtained between the calculations and measurements in the acoustic pipe.

关键词： low-frequency acoustic properties,dynamic mechanical properties,Principles of Time-Temperature Superposition,acoustic pipe,sound absorption coefficient.

MULTIVARIATE FOURIER SERIES OVER A CLASS OF NON TENSOR-PRODUCT PARTITION DOMAINS

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Journal of Computational Mathematics 2003年第1期21卷 53-62页

作者： Jiachang Sun(Parallel Computing Division, Institute of software, chinese academy of sciences, beijing 100080,{3.) Parallel Computing Division Institute of Software Chinese Academy of Sciences 北京 100080

This paper finds a way to extend the well-known Fourier methods, to so-called n+1 directions partition domains in n-dimension. In particular, in 2-D and 3.D cases, we study Fourier methods over 3.direction parallel hexagon partitions and 4-direction parallel parallelogram dodecahedron partitions, respectively. It has pointed that, the most concepts and results of Fourier methods on tensor-product case, such as periodicity,orthogonality of Fourier basis system, partial sum of Fourier series and its approximation behavior, can be moved on the new non tensor-product partition case.

关键词： Multivariate Fourier methods Non tensor-product partitions Multivariate Fourier series

A formal model of fair exchange protocols

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Science in china(Series F) 2005年第4期48卷 499-512页

作者： QING Sihan1,2,3.& LI Gaicheng1,2,3.1. Engineering Research Center for Information Security Technology, Institute of software, chinese Aca- demy of sciences,{3., china 2. beijing Zhongke Ansheng Corporation of Information Technology,{3., china 3. Graduate School of the chinese academy of sciences, beijing 10003., china 1. Engineering Research Center for Information Security Technology Institute of Software Chinese Academy of Sciences 100080 Beijing China 2. beijing Zhongke Ansheng Corporation of Information Technology 100080 Beijing China 3. Graduate School of the chinese academy of sciences 100039 Beijing China

Based on the study of existing fair exchange protocols, this paper sets up an accurate formal model by stepwise refinement. In the process of refinement an unreliable channel is employed to simulate an attack behavior. The model provides a novel formal definition of exchanged items, and presents the formal goals for fairness, accountability, etc., reflecting the inherent requirements for fair exchange protocols across-the-board. In order to check, prove, and design fair exchange protocols effectively and efficiently, the model puts forward a novel property of abuse-freeness which applies to all fair exchange protocols, gives a formal definition for trust strand of the third party, and presents general criteria of designing a secure and effective fair exchange protocol. Taking a typical fair exchange protocol as an example, this paper presents the analysis steps of fair exchange protocols appealing to our model. An unknown attack is uncovered. The analysis reveals the process of a complete attack, discovering deeper reasons for causing an attack. Finally, we modify the flawed protocol and the revised protocol ensures the desirable properties.

关键词： events local causal relation local temporal relation global relation exchanged item security goals.

software Engineering Technology for the 21^(st) Century

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Wuhan University Journal of Natural sciences 2001年第Z1期6卷 152-158页

作者： Cheng Hu Institute of software, chinese academy of sciences beijing 100080,{3. Institute of software Chinese Academy of Sciences Beijing 100080 China

In this paper we will discuss the software engineering technology for the 21 st century. First we review development over the last half century, overview application requirement and environment, accept a challenge. Then we outline following software engineering techniques: 1) Process;2) Analysis;3. Design;4) UML;5) Component;6) Java +XML;7) Integrated;8) Quality(ISO9000&CMM).

关键词： software engineering object oriented component Java UML CMM ISO9000

Mechanism and Defense on Malicious Code

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Wuhan University Journal of Natural sciences 2005年第1期10卷 83-88页

作者： WEN Wei-ping 1,2,3. QING Si-han 1,2,3.1. Institute of software, the chinese academy of sciences, beijing 100080,{3. 2.Engineering Research Center for Information Security Technology, the chinese academy of sciences, beijing 100080,{3. 3.Graduate School of the chinese academy of sciences, beijing 100080,{3. Institute of software the Chinese Academy of Sciences Beijing 100080 China

With the explosive growth of network applications, the threat of the malicious code against network security becomes increasingly serious. In this paper we explore the mechanism of the malicious code by giving an attack model of the malicious code, and discuss the critical techniques of implementation and prevention against the malicious code. The remaining problems and emerging trends in this area are also addressed in the paper.

关键词： malicious code attacking model mechanism defense system security network security

Modeling of elastic wave propagation on a curved free surface using an improved finite-difference algorithm

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Science china(Physics,Mechanics & Astronomy) 2004年第5期47卷 633-648页

作者： WANG Xiuming1,3.& ZHANG Hailan2 1. CSIRO Petroleum, ARRC, PO BOX 113., Technology Park, Bentley, WA 6102, Australia 2. Institute of Acoustics, chinese academy of sciences, beijing 100080, china 3. Present address: Institute of Acoustics, chinese academy of sciences, beijing 100080, china 1. CSIRO Petroleum ARRC Technology Park PO BOX 1130 6102 Bentley WA Australia 2. Institute of Acoustics Chinese Academy of Sciences 100080 Beijing China

Based on existing direct and imaging methods of a staggered finite-difference scheme, an improved algorithm for staggered finite-difference is proposed to implement rugged topographic free boundary conditions. This method assumes that the free surface can be implemented with horizontal and vertical free surface segments and their corners; the free surface passes through the grid points of shear stress components, instead of the normal stress components. Imaging is carried out for stress components in both horizontal and vertical directions, thus increasing the accuracy. To update particle- velocities, imaging and updating are first performed in the horizontal direction, and then in the vertical direction. The numerical results for elastic flat horizontal free surface with the imaging method and those for flat free surfaces of various slope angles with the proposed method are compared, and are shown to be in good agreement. The advantage of the proposed method is that only the stresses are dealt with in implementing the free surface into the staggered algorithm, which improves computation efficiency.

关键词： elastic wave simulation, curved free surface, staggered finite-difference, algorithm stability.