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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.,china 2.Department of Computer Science and Technology,tsinghua university,{2.,china 3 network research Center,tsinghua university,{2.,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

Electric-stimulus rate encoding algorithm of Mandarin tonal information in cochlear implant

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Progress in Natural Science:Materials International 2006年第12期16卷 1315-1321页

作者： GUAN Tian~1, GONG Qin~1 and YE Datian~2.*(1. Department of Biomedical Engineering, tsinghua university, beijing 100084, {2. 2. research Center of Biomedical Engineering, Graduate School at Shenzhen, tsinghua university, Shenzhen 518055, {2.) [a]Department of Biomedical Engineering Tsinghua University Beijing China [b]research Center of Biomedical Engineering Graduate School at Shenzhen Tsinghua University Shenzhen China

The modern multi-channel cochlear implants usually extract and encode the temporal envelope cues. This kind of algorithms can hardly satisfy the users who speak tonal languages, such as Mandarin. Many studies have tried to enhance the recognition ability of Mandarin through encoding tonal information and made suggestions to frequency-modulate the fixed pulse-rate carrier with the extracted tonal information based on the rate-pitch theory in electric hearing. However, how to encode and deliver the tonal information such as F_0by changing electric-stimulus rate has not got further study in clinical electric-stimulus mode. The present paper focuses on this matter by piecewise calculating the appreciable electric-stimulus rates. Then an electric-stimulus encoding algorithm of Mandarin tone is brought forward and testified through acoustic simulations. Such conclusion can be drawn that this algorithm of electric-stimulus rate could convey tonal information well and help to enhance the Mandarin speech recognition ability.

关键词： cochlear implant tone fundamental frequency electric-stimulus rate.

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,{2.,beijing 100084,china 2.Department of Computer Science and Technology,{2.,beijing 100084,china 3 tsinghua National Laboratory for Information Science and Technology(TNList) ,beijing 100084,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)

A preliminary study on vegetation-erosion dynamics and its applications

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Science china Earth Sciences 2005年第5期48卷 689-700页

作者： WANG Zhaoyin 1,2., WANG Guangqian 1 , LI Changzhi 1 & WANG Feixin 1 1. Department of Hydraulic Engineering, tsinghua university, beijing 100084, {2. 2. International research and Training Center on Erosion and Sedimentation, beijing 100084, {2. 1. Department of Hydraulic Engineering Tsinghua University 100084 Beijing China 2. International research and Training Center on Erosion and Sedimentation 100084 Beijing China

Vegetation-erosion dynamics is a new interdisciplinary science, studying the laws of evolution of watershed vegetation under the action of various ecological stresses. Introducing a qualitative expression of ecological stresses in this paper, the present authors establish the cou- pled differential equations for the vegetation-erosion process and derive a theoretical solution. The model is applied to the Anjiagou watershed on the Loess Pateau and the Xiaojiang water- shed and its sub-watersheds on the Yunnan Plateau. The calculated results agree well with the vegetation development processes. Abstracted from the differential equations the so-called vegetation-erosion chart is worked out, with which we can predict the development trend of vegetation under no human stresses. It is demonstrated that the erosion control is important for vegetation development and reforestation must be a long-term strategy. On the Yunnan Plateau with relatively high precipitation and temperature, vegetation can be greatly improved if erosion is controlled. On the dry and cold Loess Pateau suffering from high rate of soil erosion, however, vegetation can effectively control erosion but erosion reduction exhibits low effectiveness on vegetation development. Vegetation in the area is not stable and management is always needed to maintain the vegetation.

关键词： vegetation-erosion dynamics, human activities, coupled differential equations, erosion control, vigor ofvegetation.

Extremal eigenvalues of measure differential equations with fixed variation

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Science china Mathematics 2010年第10期53卷 2573-2588页

作者： ZHANG MeiRong 1,2.1 Department of Mathematical Sciences,tsinghua university,beijing 100084,{2. 2.Zhou Pei-Yuan Center for Applied Mathematics,tsinghua university,beijing 100084,{2. 1. Department of Mathematical Sciences Tsinghua University Beijing 100084 China2. Zhou Pei-Yuan Center for Applied Mathematics Tsinghua University Beijing 100084 China

In this paper we will study eigenvalues of measure differential equations which are motivated by physical problems when physical quantities are not absolutely *** taking Neumann eigenvalues of measure differential equations as an example,we will show how the extremal problems can be completely solved by exploiting the continuity results of eigenvalues in weak* topology of measures and the Lagrange multiplier rule for nonsmooth *** results can give another explanation for extremal eigenvalues of SturmLiouville operators with integrable potentials.

关键词： measure differential equation eigenvalue extremal value weak* topology Frechét derivative sub-differential

Density-functional formula for strongly correlated systems

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Progress in Natural Science:Materials International 2005年第5期15卷 395-401页

作者： WANG Huaiyu1*, HAN Rushan2.and CHEN Nanxian1(1. Department of Physics, tsinghua university, beijing 100084, {2. 2. Department of Physics, Peking university, beijing 100871, {2.) Department of Physics Tsinghua University Beijing 100084 China Department of Physics Peking University Beijing 100871 China

Density functional method is applied for strongly correlated systems. Based on the assumption that the systems are composed of electrons in singly-occupied orbitals and those in doubly-occupied orbitals, a set of self-consistent equations are obtained by standard variation procedure. The equations consist of two parts. One part is to solve the wave functions of the electrons in singly-occupied orbitals and the other is to solve the wave functions of the electrons in doubly-occupied orbitals. The physical meanings of the terms appearing in the equations are discussed.

关键词： density-functional theory strongly correlated systems doubly-occupied orbital two-particle wave function self-consistent equations.

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

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Science china(Information 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, tsinghua university, beijing 100084, {2. 2.tsinghua National Laboratory for Information Science and Technology, tsinghua university, beijing 100084, {2. 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

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.tsinghua National Laboratory for Information Science and Technology, 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 Laboratory 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

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,{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 and Technology Tsinghua University Beijing 100084 China 3. ]tsinghua National Laboratory 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