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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, china 2 tsinghua National Laboratory for information Science and technology, tsinghua university, beijing 100084, china 3.research institute of information technology (RIIT), tsinghua university, beijing 100084, china 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 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 Science and technology,tsinghua university,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)

GHG emission reductions and costs to achieve Kyoto target

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Journal of Environmental Sciences 2003年第4期15卷 541-547页

作者： CHEN Wen\|ying (Energy, Environment and Economy research institute, tsinghua university, beijing 100084, china.) Energy Environment and Economy Research Institute Tsinghua University 北京 100084

Emission projection and marginal abatement cost curves(MACs) are the central components of any assessment of future carbon market, such as CDM (clean development mechanism) potentials, carbon quota price etc. However, they are products of very complex, dynamic systems driven by forces like population growth, economic development, resource endowments, technology progress and so on. The modeling approaches for emission projection and MACs evaluation were summarized, and some major models and their results were compared. Accordingly, reduction and cost requirements to achieve the Kyoto target were estimated. It is concluded that Annex I Parties' total reduction requirements range from 503—1304 MtC with USA participation and decrease significantly to 140—612 MtC after USA's withdrawal. Total costs vary from 21—77 BUSD with USA and from 5—36 BUSD without USA if only domestic reduction actions are taken. The costs would sharply reduce while considering the three flexible mechanisms defined in the Kyoto Protocol with domestic actions' share in the all mitigation strategies drops to only 0—16%.

关键词： Kyoto Protocol emission reduction abatement cost flexible mechanisms

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,china 2 Network research Center,tsinghua university,beijing 100084,china 3 tsinghua National Laboratory for information Science and technology(TNList) ,beijing 100084,china 1. Department of Computer Science Tsinghua University Beijing 100084 China 2. Network research Center Tsinghua University Beijing 100084 China 3. tsinghua National Laboratory 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 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,china 2 Network research Center,tsinghua university,beijing 100084,china 3 tsinghua 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 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

Building a next generation Internet with source address validation architecture

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Science in china(Series F) 2008年第11期51卷 1681-1691页

作者： WU JianPing1,3,REN Gang1,3 & LI Xing2,3 1 Department of Computer Science,tsinghua university,beijing 100084,china 2 Department of Electronic Engineering,tsinghua university,beijing 100084,china 3 tsinghua National Laboratory for information Science and technology(TNList) ,beijing 100084,china Department of Computer Science Tsinghua University Beijing 100084 China Department of Electronic Engineering Tsinghua University Beijing 100084 China tsinghua National Laboratory for information Science and technology (TNList) Beijing 100084 China

The IP packet forwarding of current Internet is mainly destination based. In the forwarding process, the source IP address is not checked in most *** causes serious security, management and accounting problems. Based on the drastically increased IPv6 address space, a ＂source address validation architecture＂（SAVA） is proposed in this paper, which can guarantee that every packet received and forwarded holds an authenticated source IP address. The design goals of the architecture are lightweight, loose coupling, ＂multi-fence support＂ and incremental deployment. This paper discusses the design and implementation for the architecture, including inter-AS, intra-AS and local subnet. The performance and scalability of SAVA are described. This architecture is deployed into the CNGI-CERNET2 infrastructure a large-scale native IPv6 backbone network of the china Next Generation Internet project. We believe that the SAVA will help the transition to a new, more secure and dependable Internet.

关键词： IP source address validation network architecture network security

Fusion tracking in color and infrared images using joint sparse representation

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Science china(information 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, tsinghua university, beijing 100084, china 2State Key Laboratory of Intelligent technology and Systems, beijing 100084, china 3tsinghua National Laboratory for information 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

Performance Modeling and Approximate Analysis of Multiserver Multiqueue Systems with Poisson and Self-similar Arrivals

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Journal of university of Science and technology beijing 2001年第2期8卷 145-151页

作者： Zhiguang Shan, Chuang Lin, Yang Yang, Yan Wang (information Engineering School, university of Science and technology beijing, beijing 100083, china) (Department of Computer Science and technology, tsinghua university, beijing 100084, china) Univ Sci & Technol beijing Informat Engn Sch Beijing 100083 Peoples R China tsinghua Univ Dept Comp Sci & Technol Beijing 100084 Peoples R China

The problem of state space explosion is still ran outstanding challenge in Markovian performance analysis for multiserver multiqueue (MSMQ) systems. The system behavior of a MSMQ system is described using stochastic high-level Petri net (SHLPN) models, and an approximate performance analysis technique is proposed based on decomposition and refinement methods as well as iteration technique. A real MSMQ system, Web-server cluster, is investigated. The performance of an integrated scheme of request dispatching and scheduling is analyzed with both Poisson and self-similar request arrivals. The study shows that the approximate analysis technique significantly reduces the complexity of the model solution and is also efficient for accuracy of numerical results.

关键词： multiserver multiqueue (MSMQ) system Web-server cluster performance analysis stochastic high-level Petri net (SHLPN) request dispatching request scheduling

Parameter identification theory of a complex model based on global optimization method

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Science china(Physics,Mechanics & Astronomy) 2008年第11期51卷 1722-1732页

作者： QU Jie1, JIN QuanLin2 & XU BingYe3 1 College of Automotive Engineering, South china university of technology, Guangzhou 510640, china 2 beijing research institute of Mechanical and Electrical technology, beijing 100083, china 3 Department of Engineering Mechanics, tsinghua university, beijing 100084, china 1. College of Automotive Engineering South China University of Technology Guangzhou 510640 China 2. beijing research institute of Mechanical and Electrical technology Beijing 100083 China 3. Department of Engineering Mechanics Tsinghua University Beijing 100084 China

With the development of computer technology and numerical simulation technology, computer aided engineering (CAE) technology has been widely applied to many fields. One of the main obstacles, which hinder the further application of CAE technology, is how to successfully identify the parameters of the selected model. An elementary framework for parameter identification of a complex model is provided in this paper. The framework includes the construction of objective function, the design of the optimization method and the evaluation of the identified results, etc. The parameter identification process is described in this framework, taking the parameter identification of the superplastic constitutive model considering grain growth for Ti-6Al-4V at 927°C as an example. The objective function is the weighted quadratic sums of the difference between the experimental and computational data for the stress-strain relationship and the grain growth relationship; the designed optimization method is a hybrid global optimization method, which is based on the feature of the objective function and incorporates the strengths of genetic algorithm (GA), the Levenberg-Marquardt algorithm and the augmented Gauss-Newton algorithm. The reliability evaluation of parameter identification result is made through the comparison between the calculated and experimental results and between the theoretical values of the parameters and the identified ones.

关键词： constitutive model parameter identification theory inverse analysis global optimization