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An introduction to tsinghua Cloud

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science china(Information sciences) 2010年第7期53卷 1481-1486页

作者： ZHENG WeiMin1,2.1department of {2. {2. and technology, tsinghua university, beijing 100084, china 2.8} National Laboratory for Information {2. and technology, beijing 100084, china department of computer {{2. and technology Tsinghua University Beijing China tsinghua National Laboratory for Information science and {{2. Beijing 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

Experimental realization of quantum cryptography communication in free space

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science china(Physics,Mechanics & Astronomy) 2005年第2期48卷 237-246页

作者： WANG Chuan1, zhang Jingfu1, WANG Pingxiao1, DENG Fuguo1, AI Qing1 & LONG Guilu1,2.1. {{2. of Physics, Key Laboratory for Quantum Information and Measurements, {2. Univer- sity, beijing 100084, china {2. Center for Atomic and Molecular Nanosciences, tsinghua university, beijing 100084, china department of Physics Key Laboratory for Quantum Information and Measurements Tsinghua University Beijing China Atomic and Molecular Nanosciences Tsinghua University Beijing China

Utilizing linear optical devices, the principle of B92.quantum key distribution (QKD) protocol is demonstrated in free space with a distance of transmission of 2.2.meters. The faint laser pulses with 650 nm wavelength are used as the single photon sources. The experimental results show that the eavesdropping behavior in the signal transmission can be detected. We also discuss the problems and solutions in using the quantum cryptography communication practically. It is pointed out that one of the approaches to increasing the distance of the quantum communication is to overcome the attenuation of the single photon in transmission. This could not be solved by the use of single photon source, and new quantum communication protocols are needed to solve these problems.

关键词： quantum key distribution, free space, linear optics, faint pulses.

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 {2. National Laboratory for Information {2. and technology,{2. university,beijing 100084,china 2.department of {12. {2. and technology,{2. university,beijing 100084,china 3 Network Research Center,{2. university,beijing 100084,china tsinghua National Laboratory for Information science and {{2. Tsinghua University Beijing China department of computer {{2. and technology Tsinghua University Beijing China Network Research Center Tsinghua University Beijing 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

Self-healing routing: failure,modeling and analysis

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science china(Information sciences) 2011年第3期54卷 609-622页

作者： XU MingWei 1,2., LI Qi 1,2., YANG Yuan 1,2., HOU MeiJia 1,2.& PAN LingTao 1,2.1 department of {2. {2., tsinghua university, beijing 100084, china 2.{12. National Laboratory for Information {2. and technology (TNList), beijing 100084, china department of computer {{2. Tsinghua University Beijing China tsinghua National Laboratory for Information science and {{2. (TNList) Beijing China

Network failures occur frequently, and self-healing ability of existing routing protocols cannot guarantee fast route convergence under these failures without impacting packet forwarding. During routing convergence, network routes may be incorrect and even routing black holes and loops occur, which will result in extensive packet loss and thus influence network performance. To solve this problem, several improved routing solutions have been proposed. In this paper, we propose the concept and model of self-healing routing and analyze the key problems in current intra-domain and inter-domain self-healing routing protocols after briefly reviewing the characteristics of network failures. We classify the different self-healing solutions into two categories based on their design principles: routing restoration and routing protection, and systematically analyze these different typical solutions. Finally, we discuss several key issues in self-healing routing and propose a hybrid protection and restoration based routing scheme.

关键词： failure intra-domain routing inter-domain routing self-healing routing

Corslet: A shared storage system keeping your data private

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science china(Information sciences) 2011年第6期54卷 1119-1128页

作者： XUE Wei 1,2., SHU JiWu 1,2., LIU Yang 1 & XUE Mao 1 1 {2. of computer {2. and technology, tsinghua university, beijing 100084, china 2.tsinghua National Laboratory for Information {2. and technology, tsinghua university, department of computer {{2. and technology Tsinghua University Beijing China tsinghua National Laboratory for Information science and {{2. Tsinghua University Beijing China

With the exponential growth of digital data, it is becoming more and more popular to store data in shared distributed storage systems inside the same organization. In such shared distributed storage systems, an ordinary user usually does not have the control permission over the whole system, and thus cannot secure data storage or data sharing of his own files. To solve this issue, this paper proposes a new system architecture to secure file storing and sharing efficiently over untrusted shared storage and network environments. Based on this architecture, this paper designs and implements a stackable secure storage system called Corslet. Corslet can run directly on deployed underlying storage systems without modification, while bringing end-to-end confidentiality and integrity as well as efficient access control for user data. For individual users, Corslet is easy to use, and does not require users to maintain or manage any keys on their client machines locally. The Bonnie++ and IOzone benchmark results show that the throughput of Corslet over NFS can achieve more than 90% of native NFS throughput in most tests, proving that Corslet can provide enhanced security for user data while maintaining acceptable performance.

关键词： storage security access control key management shared file system

Compactness in fuzzy logic

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Chinese science Bulletin 1998年第14期43卷 1166-1171页

作者： YING Mingsheng department of computer {{2. and technology, tsinghua university, beijing 100084, china department of computer {{2. and technology Tsinghua University Beijing China

Compactness in Pavelka’s fuzzy logic for some compact lattices of truth values is shown, and the concept of gradual compactness is introduced to establish some corresponding results in a more general setting.

关键词： fuzzy logic compactness gradual compactness.

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.. Key Laboratory for Atomic and Molecular Nano{2.s, and {2. of Physics, tsinghua university, beijing 100084, china 2. Center of Quantum Information {2. and technology, tsinghua National Laboratory for information {2. and technology, beijing 100084, china 3. Institute of Physics, School of {2.s, beijing university of Posts and Telecommunications, beijing 100876, china) Key Laboratory for Atomic and Molecular Nanosciences Department of Physics Tsinghua University Beijing 100084 China Center of Quantum Information science and technology 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.

Study on the two and three-parameter working stability regions of 3Y-TZP suspension

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science china(Technological sciences) 2006年第5期49卷 547-568页

作者： CHEN Youqiang1, 2. zhang Xinni3, CHEN Sha’ou3 & QI Ping3 1. {2. of Chemistry, Qingdao {2., Qingdao 2.6071, china 2. {2. of Chemistry, tsinghua university, beijing 100084, china 3. {2. of Physics, Qingdao {2., Qingdao 2.6071, china department of Chemistry Qingdao University Qingdao China department of Chemistry Tsinghua University Beijing China department of Physics Qingdao University Qingdao China

We determined the variation tendency of viscosity (η) at various solids load- ing (α) for 3Y-TZP suspension as a function of dispersant concentration (Cw) using vis- cosity measurement, measured the diameter of particles as a function of Cw in very dilute suspension using light scattering method, and obtained the surface features of the sedi- ment of suspension with different Cw using SEM. We also discussed the influence of the microstructure of adsorbed polymer layers on particles and their interactions in the dis- persing medium on the stability of suspension. Then two different stable states and two different unstable states for 3Y-TZP suspension were given. Accordingly, the (Cw, η), (Cw, α), and (α, η) two-parameter, and (Cw, α, η) three-parameter stability maps were con- structed. Based on the DLVO theory calculations, the dispersant concentration, particle distance (r), and interparticle potential energy (VT) maps with various solids loading for 3Y-TZP aqueous suspension were also constructed. In (Cw, r) two-parameter coordinate system, the stable motion region map for particles was established. The Cw, α, and VT,max (the highest potential energy) surface of the potential barrier map was obtained through calculation and simulation on the basis of the surfaces of Cw, r, VT maps introduced above. The (Cw, α) two-parameter stability map was then obtained from the Cw, α, VT,max map. The results showed that this theoretical map can qualitatively prove the experimentally obtained results—the existence of different dispersed states of particles in suspension system and the variation tendency of suspension stability with changing each parame- ter—were reasonable.

关键词： 3Y-TZP, suspension, stability, DLVO theory, interparticle potential energy.

A stochastic policy search model for matching behavior

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science china(Information sciences) 2011年第7期54卷 1430-1443页

作者： CHENG ZhenBo 1,2.zhang Yu 1 & DENG ZhiDong 1 1 State Key Laboratory on Intelligent {2. and Systems,{2. National Laboratory for Information science and {2.,department of computer science,{2. university,beijing {12.,{12. 2.department of computer science and {2.,Zhejiang university of {2.,Hangzhou 310014,{12. State Key Laboratory on Intelligent technology and Systems Tsinghua National Laboratory for Information Science and Technology Department of Computer Science Tsinghua University Beijing China department of computer {{2. and technology Zhejiang University of Technology Hangzhou China

The matching law is one of the basic empirical laws in decision theory,and it states that a subject’s preference to optional targets depends on which choices are *** this paper,we study the possible mechanisms that explain why subjects’ decisions often obey this *** the basis of reinforcement learning theory,we put forward a decision-making model in which the policy is updated by a policy parameter,and the model might be implemented in the brain through the prefrontal cortex and the basal ganglia neural *** on this model,an algorithm that satisfies the matching law is derived under some simple *** analysis and simulation results show that the decision behavior achieved by the algorithm obeys the matching *** addition,the matching behaviors in two classical experiments are reproduced using the *** results provide a reasonable strategy for the matching law and a useful computational tool for rewarded decision-making tasks.

关键词： policy model matching law reinforcement learning decision-making model