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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 2.5}, {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

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, tsinghua 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 {2. 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.

Fusion tracking in color and infrared images using joint sparse representation

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science china({2. sciences) 2012年第3期55卷 590-599页

作者： LIU HuaPing1,2.3 & SUN FuChun1,2.3 1Department of Computer science and technology, {2. University, beijing 100084, china 2.tate Key laboratory of Intelligent technology and Systems, beijing 100084, china 3{2. national laboratory for {12. science and technology, beijing 100084, china 1. Department of Computer science and technology Tsinghua University Beijing 100084 China2. State Key Laboratory of Intelligent Technology and Systems Beijing 100084 China3. Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

Currently sparse signal reconstruction gains considerable interest and is applied in many fields. In this paper, a similarity induced by joint sparse representation is designed to construct the likelihood function of particle filter tracker so that the color visual spectrum and thermal spectrum images can be fused for object tracking. The proposed fusion scheme performs joint sparse representation calculation on both modalities and the resultant tracking results are fused using min operation on the sparse representation coefficients. In addition, a co-learning approach is proposed to update the reference templates of both modality and enhance the tracking robustness. The proposed fusion scheme outperforms state-of-the-art approaches, and its effectiveness is verified using OTCBVS database.

关键词： joint sparse representation fusion tracking color image infrared image

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

Corslet: A shared storage system keeping your data private

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science china({2. 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 Department of Computer science and technology, {2. University, beijing 100084, china 2.5}, {2. University, 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

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

Buffer planning for application-specific networks-on-chip design

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science in china(Series F) 2009年第4期52卷 547-558页

作者： YIN ShouYi1,2.LIU LeiBo1,2.& WEI ShaoJun1,2.1 Institute of Microelectronics,tsinghua University,beijing {2.,china 2.national laboratory for information science and technology,tsinghua University,beijing {2.,china Institute of Microelectronics Tsinghua University Beijing 100084 China national laboratory for {2. science and technology Tsinghua University Beijing 100084 China

Networks-on-chip （NoC） is a promising communication architecture for next generation SoC. The size of buffer used in on-chip routers impacts the silicon area and power consumption of NoC dominantly. It is important to plan the total buffer-size and each router buffer-allocation carefully for an efficient NoC design. In this paper, we propose two buffer planning algorithms for application-specific NoC design. More precisely, given the traffic parameters and performance constraints of target application, the proposed algorithms automatically determine minimal buffer budget and assign the buffer depth for each input channel in different routers. The experimental results show that the proposed algorithms can significantly reduce total buffer usage and guarantee the performance requirements.

关键词： buffer planning networks-on-chip (NoC) design automation optimization

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

Real-time reliability prediction for dynamic systems with both deteriorating and unreliable components

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science in china(Series F) 2009年第11期52卷 2234-2246页

作者： XU ZhengGuo1,2. JI YinDong2.3 & ZHOU DongHua1,2. 1 Department of Automation, tsinghua University, beijing 100084,{2. 2.3}, tsinghua University, beijing 100084,{2. 3 Research Institute of information technology (RIIT), tsinghua University, beijing 100084,{2. Department of Automation Tsinghua University Beijing 100084 China tsinghua national {2. for information science and technology Tsinghua University Beijing 100084 China Research Institute of information technology (RIIT) Tsinghua University Beijing 100084 China

As an important technology for predictive maintenance, failure prognosis has attracted more and more attentions in recent years. Real-time reliability prediction is one effective solution to failure prognosis. Considering a dynamic system that is composed of normal, deteriorating and unreliable components, this paper proposes an integrated approach to perform real-time reliability prediction for such a class of systems. For a deteriorating component, the degradation is modeled by a time-varying fault process which is a linear or approximately linear function of time. The behavior of an unreliable component is described by a random variable which has two possible values corresponding to the operating and malfunction conditions of this component. The whole proposed approach contains three algorithms. A modified interacting multiple model particle filter is adopted to estimate the dynamic system＇s state variables and the unmeasurable time-varying fault. An exponential smoothing algorithm named the Holt＇s method is used to predict the fault process. In the end, the system＇s reliability is predicted in real time by use of the Monte Carlo strategy. The proposed approach can effectively predict the impending failure of a dynamic system, which is verified by computer simulations based on a three-vessel water tank system.

关键词： reliability failure prognostics dynamic systems fault prediction particle filtering interacting multiple model exponential smoothing,predictive maintenance