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Fuzzy tolerance quotient spaces and fuzzy subsets

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science china({2. sciences) 2010年第4期53卷 704-714页

作者： ZHANG Ling1 & ZHANG Bo2.3,4* 1Computer science & technology College, Anhui University, Anhui 2.0039,{2. 2.tate Key laboratory of Intelligent technology and Systems, Beijing 100084,{2. 3tsinghua national laboratory of information science & technology, Beijing 100084,{2. 4information science & technology College, Computer science & technology Department, tsinghua University, Beijing 100084,{2. 1. Computer science & technology College Anhui University Anhui 230039 China2. State Key Laboratory of Intelligent Technology and Systems Beijing 100084 China3. Tsinghua National Laboratory of Information Science & Technology Beijing 100084 China4. Information Science & Technology College Computer Science & Technology Department Tsinghua University Beijing 100084 China

The structure and characteristic of fuzzy subsets are discussed by using the concepts of granulation and hierarchy in quotient space theory. First, the equivalence relation based quotient space theory is extended to the fuzzy tolerance relation. Second, the isomorphism and its discriminant of fuzzy tolerance relations are discussed. Finally, by using the fuzzy tolerance relation to define the fuzzy subset, its properties are addressed. The main results are given below: (1) several equivalent statements of fuzzy tolerance relations; (2. the definition of isomorphism of fuzzy tolerance relations; (3) the isomorphic discriminant of fuzzy tolerance relations; (4) the definition and properties of fuzzy subsets based on the fuzzy tolerance relations; and (5) the necessary and sufficient condition of the isomorphism of fuzzy subsets. These results will help us further comprehend the concepts of fuzzy tolerance relations and fuzzy subsets.

关键词： Fuzzy tolerance relation quotient space isomorphism fuzzy subset

An introduction to tsinghua Cloud

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science china({2. sciences) 2010年第7期53卷 1481-1486页

作者： ZHENG WeiMin1,2.1Department of Computer science and technology, {2. University, Beijing 100084, china 2.2. national laboratory for information science and technology, Beijing 100084, china 1. Department of Computer science and technology Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

Cloud computing has become a trend that draws attention from both academia and industry all over the world. This paper unveils details of tsinghua Cloud, a comprehensive solution for cloud computing developed by Tsing... 详细信息

关键词： cloud computing distributed file system virtual computing environment data sharing

Influence of magnetic current on the ground state entanglement in an isotropic transverse XY chain

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Progress in Natural science:Materials International 2007年第10期17卷 1147-1151页

作者： Liu Dan1,2., Zhang Yong3 and Long Guilu1,2.1. Key laboratory for Atomic and Molecular Nanosciences, and Department of Physics, {2. University, Beijing 100084, china 2. Center of Quantum information science and technology, {2. national laboratory for information science and technology, Beijing 100084, china 3. Institute of Physics, School of sciences, Beijing University of Posts and Telecommunications, Beijing 100876, china) Key laboratory for Atomic and Molecular Nanosciences and Department of Physics Tsinghua University Beijing 100084 China Center of Quantum information science and {2. Tsinghua National Laboratory for information Science and Technology Beijing 100084 China Institute of Physics School of Sciences Beijing University of Posts and Telecommunications Beijing 100876 China

We study the ground state entanglement in a three-qubit XY chain under the influence of a magnetization current. It is found that the ground state changes from a W state to a disentangled state as the magnetic field varies. When the Lagrange multiplier λ>3, namely under a strong magnetic current, the ground state holds onto a W state for a large range of the magnetic field strength. A phase transition to the magnetization-current phase occurs under a certain condition.

关键词： Heisenberg-XY chain magnetic-current phase transition.

RRM:An incentive reputation model for promoting good behaviors in distributed systems

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science in china(Series F) 2008年第11期51卷 1871-1882页

作者： ZHANG Hong1,2.DUAN HaiXin1,3 & LIU Wu1,3 1 tsinghua national {2. for information science and technology,tsinghua University,Beijing 100084,china 2.Department of Computer science and technology,tsinghua University,Beijing 100084,china 3 Network Research Center,tsinghua University,Beijing 100084,china 1. tsinghua national {2. for information science and technology Tsinghua University Beijing 100084 China 2. Department of Computer science and technology Tsinghua University Beijing 100084 China 3. Network Research Center Tsinghua University Beijing 100084 China

Reputation systems represent soft security mechanisms that complement traditional information security mechanisms. They are now widely used in online e-commerce markets and communities in order to stimulate good behaviors as well as to restrain adverse behaviors. This paper analyzes the limitations of the conversational reputation models and proposes an incentive reputation model called the resilient reputation model （RRM） for the distributed reputation systems. The objective of this reputation model is not only to encourage the users to provide good services and, therefore, to maximize the probability of good transaction outcomes, but also to punish those adverse users who are trying to manipulate the application systems. The simulation results indicate that the proposed reputation model （RRM） could effectively resist against the common adverse behaviors, while protecting the profits of sincere users from being blemished by those adversaries.

关键词： reputation model distributed system trust soft security

A formal method to real-time protocol interoperability testing

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science in china(Series F) 2008年第11期51卷 1723-1744页

作者： WANG ZhiLiang1,3,YIN Xia2.3 & JING ChuanMing2.3 1 Network Research Center,tsinghua University,Beijing 100084,china 2.Department of Computer {2. and technology,tsinghua University,Beijing 100084,china 3 tsinghua national laboratory for information {2. and technology(TNList) ,Beijing 100084,china 1. Network Research Center Tsinghua University Beijing 100084 China 3. tsinghua national {2. for information science and technology (TNList) Beijing 100084 China 2. Department of Computer science and technology Tsinghua University Beijing 100084 China

Interoperability testing is an important technique to ensure the quality of implementations of network communication protocol. In the next generation Internet protocol, real-time applications should be supported effectively. However, time constraints were not considered in the related studies of protocol interoperability testing, so existing interoperability testing methods are difficult to be applied in real-time protocol interoperability testing. In this paper, a formal method to real-time protocol interoperability testing is proposed. Firstly, a formal model CMpTIOA （communicating multi-port timed input output automata） is defined to specify the system under test （SUT） in real-time protocol interoperability testing; based on this model, timed interoperability relation is then defined. In order to check this relation, a test generation method is presented to generate a parameterized test behavior tree from SUT model; a mechanism of executability pre-determination is also integrated in the test generation method to alleviate state space explosion problem to some extent. The proposed theory and method are then applied in interoperability testing of IPv6 neighbor discovery protocol to show the feasibility of this method.

关键词： protocol testing interoperability testing real-time testing test generation timed input output automata(TIOA)

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,{2. 2.Network Research Center,tsinghua University,Beijing 100084,{2. 3 tsinghua national laboratory for information science and technology(TNList) ,Beijing 100084,{2. 1. Department of Computer science Tsinghua University Beijing 100084 China 2. Network Research Center Tsinghua University Beijing 100084 China 3. tsinghua national {2. for information science and technology (TNList) Beijing 100084 China

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

A user-space file system for on-demand legacy desktop software

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science china({2. sciences) 2011年第6期54卷 1142-1150页

作者： ZHANG YouHui 1,2., SU GeLin 1,2.& ZHENG WeiMin 1,2.1 Department of Computer science and technology, {2. University, Beijing 100084, china 2.{2. national laboratory for information science and technology, {2. University, Beijing 100084, china 1. Department of Computer science and technology Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China

Some user-level virtualization technologies have been used to convert legacy software (like the existing Windows desktop applications) into the on-demand software without any modification. To give the client a friendly and compatible method to access on-demand legacy software across the Internet, this paper presents a clientend file system for this usage case. It is a Windows user-space file system based on the cloud storage (where the on-demand software is stored), which converts the local file system accesses into remote visits. Quite a few optimizations are adopted and adjusted to suit the file-access-pattern of on-demand software, including the local cache, metadata/data/software prefetch and content-addressable storage (CAS), to decrease the number of remote visits and/or to overlap IO (input/output) operations with software execution. Detailed access-pattern analyses are also presented. This file system has been implemented and tests show that it is practical for much daily-used software-a local cache of limited size can provide up to 80% hit ratio and the corresponding overhead of running-time is about 37%. Owing to this method, on any compatible and networked computer, a user can use his/her personalized software conveniently although it does not exist on the local host.

关键词： on-demand software software as a service user-space file system cloud storage

An N/4 fixed-point duality quantum search algorithm

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中国科学：物理学、力学、天文学英文版 2010年第9期53卷 1765-1768页

作者： HAO Liang1,LIU Dan2.& LONG GuiLu1,3 1Key laboratory for Atomic and Molecular Nanosciences and Department of Physics,{2. University,Beijing 100084,china 2.chool of sciences,Dalian nationalities University,Dalian 116600,china 3tsinghua national laboratory for information science and technology,Beijing 100084,china 1. Key laboratory for Atomic and Molecular Nanosciences and Department of Physics Tsinghua University Beijing 100084 China2. School of Sciences Dalian Nationalities University Dalian 116600 China3. Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

Here a fixed-point duality quantum search algorithm is *** algorithm uses iteratively non-unitary operations and measurements to search an unsorted *** the marked item is found,the algorithm stops *** algorithm uses a constant non-unitary operator,and requires N/4 steps on average(N is the number of data from the database) to locate the marked *** implementation of this algorithm in a usual quantum computer is also demonstrated.

关键词： fixed-point search algorithm duality quantum computing the N4 duality search algorithm

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,{2. University,Beijing 100084,china 2.Network Research Center,{2. University,Beijing 100084,china 3 {2. national laboratory for information science and technology(TNList) ,Beijing 100084,china 1. Department of Computer science and technology Tsinghua University Beijing 100084 China 3. ]tsinghua national {2. for information science and technology (TNList) Beijing 100084 China 2. Network Research Center Tsinghua University Beijing 100084 China

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