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Some preservation of stability of modules

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Chinese science Bulletin 1997年第19期42卷 1596-1599页

作者： WANG HanpinDepartment of computer science and technology. peking university, beijing 100871, china Department of computer science and technology Peking University Beijing China

IN model theory, Zil’ ber has proved that any model of nontrivial -categorical theory is verysimilar to a module or field. So some people wanted to prove the famous Vaught’s conjec-ture for superstable theories of modules. Later, Buechler proved that the Vaught’s conjectureis true for the theories of modules with Morley rank 1. In order to reduce Vaught’s conjec-ture for superstablc theories of modules, Prest suggested discussing the preservation of stabili-ty--theory properties of modules when the underlying ring of the modules changes. Zieglergave some preservation theorems of clementary properties of the theory of modules in ref.

关键词： model theory ω-stahility superstability ring of fractions fractional module.

Kinetic characteristics of continuous flow polymerase chain reaction chip: A numerical investigation

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science china(Technological sciences) 2010年第7期53卷 1967-1972页

作者： WANG ShiYing1 & WANG Wei2,3 1 School of Physics, peking university, beijing 100871, china 2 institute of Microelectronics, peking university, beijing 100871, china 3 National Key Laboratory of science and technology on Micro/Nano Fabrication, beijing 100871, china School of Physics Peking University Beijing China institute of Microelectronics Peking University Beijing China National Key Laboratory of science and technology on Micro/Nano Fabrication Beijing China

Continuous flow PCR (polymerase chain reaction) chip holds impressive advantages compared to micro chamber PCR chip. In order to have better understanding of kinetic characteristics of continuous flow PCR chip, a comprehensive mathematical model is presented in this paper, including melting, annealing and extension phases of a typical PCR process which has the essence of a convection-diffusion-reaction system. Using this model, we can simulate the PCR process in series of reaction cycles. Numerical results show that the average sample velocity plays a significant role in affecting the amplification efficiency. Also, appropriate combination of the PCR mixture is important for high-quality DNA amplification. Giving a large initial DNA concentration range, the continuous flow PCR scheme holds excellent real-time detection ability theoretically. The present numerical model bridges the temperature distribution to the real DNA amplification, and thereby is able to successfully predict continuous flow PCR properties which are important for the chip design.

关键词： continuous flow PCR chip numerical simulation convection-diffusion-reaction system

AutoProc: An automatic proactive replication scheme for P2P storage

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science china(Information sciences) 2011年第6期54卷 1151-1160页

作者： YANG Zhi & DAI YaFei computer science Department, peking university, beijing 100871, china computer science Department Peking University Beijing China

Due to the prevalence of peer departures, P2P storage systems need to constantly generate replicas for high durability. However, few existing systems are able to select the right replication rate that balances replication cost and durability, e.g., minimizing replication cost without threatening the durability target. In this paper, we propose a method called AutoProc to automate the replication process in P2P storage systems. AutoProc employs two key techniques to enable cost-effective replication: correctly adapting replication rate with a reliability model, and replicating objects at the right order with a reliability indicator. Extensive simulations based on the real system failure trace show that AutoProc achieves the near-optimal performance.

关键词： P2P storage churn durability fault tolerance proactive replication resource usage

New numerical algorithms in SUPER CE/SE and their applications in explosion mechanics

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science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 237-243页

作者： WANG Gang1,2,WANG JingTao1 & LIU KaiXin1,3 1 LTCS and College of Engineering,peking university,beijing 100871,china 2 LHD,institute of Mechanics,Chinese Academy of sciences,beijing 100190,china 3 Center for Applied Physics and technology,peking university,beijing 100871,china LTCS and College of Engineering Peking University Beijing China LHD Institute of Mechanics Chinese Academy of Sciences Beijing China Center for Applied Physics and technology Peking University Beijing China

The new numerical algorithms in SUPER/CESE and their applications in explosion mechanics are studied. The researched al-gorithms and models include an improved CE/SE (space-time Conservation Element and Solution Element) method,a local hybrid particle level set method,three chemical reaction models and a two-fluid model. Problems of shock wave reflection over wedges,explosive welding,cellular structure of gaseous detonations and two-phase detonations in the gas-droplet system are simulated by using the above-mentioned algorithms and models. The numerical results reveal that the adopted algorithms have many advantages such as high numerical accuracy,wide application field and good compatibility. The numerical algo-rithms presented in this paper may be applied to the numerical research of explosion mechanics.

关键词： new algorithm SUPER CE/SE numerical simulation explosion mechanics

Technical framework for Internetware: An architecture centric approach

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science in china(Series F) 2008年第6期51卷 610-622页

作者： YANG FuQing1,2, Lü Jian3,4 & MEI Hong1,2 1 Key Laboratory of High Confidence Software Technologies (peking university), Ministry of Education, beijing 100871, china 2 School of Electronics Engineering and computer science, peking university, beijing 100871, china 3 State Key Laboratory for Novel Software technology, Nanjing 210093, china 4 Department of computer science and technology, Nanjing university, Nanjing 210093, china Key Laboratory of High Confidence Software Technologies (peking university) Ministry of Education Beijing China School of Electronics Engineering and computer science Peking University Beijing China State Key Laboratory for Novel Software technology Nanjing China Department of computer science and technology Nanjing University Nanjing China

Being a new software paradigm evolved by the Internet, Internetware brings many challenges to the traditional software methods and techniques. Sponsored by the national basic research program （973）, researchers in china have developed an architecture centric technical framework for the definition, incarnation and engineering of Internetware. First of all, a software model for Internetware is defined for what to be, including that Internetware entities should be packaged as components, behaving as agents, interoperating as services, collaborating in a structured and on demand manner, etc. Secondly, a middleware for Internetware is designed and implemented for how to be, including that Internetware entities are incarnated by runtime containers, structured collaborations are enabled by runtime software architecture, Internetware can be managed in a reflective and autonomic manner, etc. Thirdly, an engineering methodology for Internetware is proposed for how to do, including the way to develop Internetware entities and their collaborations by transforming and refining a set of software architectures which cover all the phases of software lifecycle, the way to identify and organize the disordered software assets by domain modeling, etc.

关键词： Internetware component software architecture agent middleware

Positioning localities from spatial assertions based on Voronoi neighboring

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science china(Technological sciences) 2010年第S1期53卷 143-149页

作者： GONG YongXi 1,2,3,LI GuiCai 1,LIU Yu 2 & YANG Jian 1 1 Shenzhen Key Lab of Recycling Economy,peking university Shenzhen Graduate School,Shenzhen 518055,china 2institute of Remote Sensing and Geographical Information Systems,peking university,beijing 100871,china 3College of Urban and Environmental science,peking university,beijing 100871,china Shenzhen Key Lab of Recycling Economy Peking University Shenzhen Graduate School Shenzhen China institute of Remote Sensing and Geographical Information Systems Peking University Beijing China College of Urban and Environmental science Peking University Beijing China

With the rapid development of Internet,much spatial information contained in non-structured or semi-structured documents is available on the World Wide *** such documents,localities are always textually described using spatial relationships and named places,instead of numerical ***,extracting positional information from locality descriptions is an important *** this paper,we bridge two aspects of locality descriptions,namely generating locality descriptions and positioning localities,and provide a method to compute probability density according to the selection probability of a reference object to describe the position of the target *** operation on uncertainty field is used to deal with locality description involving multiple reference *** metrics are introduced to measure the results of positioning *** choose the mixed selection probability function based on Euclidean distance and Voronoi stolen-area to compute probability density ***,we use three cases to demonstrate the proposed methods.

关键词： geographic information science positioning locality Voronoi neighboring probability density function

The driving force for development of IC and systemin future: Reducing the power consumption andimproving the ratio of performance to powerconsumption

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science china(Information sciences) 2011年第5期54卷 915-935页

作者： WANG YangYuan institute of Microelectronics, peking university, beijing 100871, china institute of Microelectronics Peking University Beijing China

With the development of information technology, integrated circuits (IC) and system which target high performance and low power consumption have widely penetrated to all the aspects of national economy, national defense construction and people’s life. With the continuous increase in IC integration density, the power consumption is becoming the limiting factor. It turns out that the driving force of the future IC and system development is the reduction of the power consumption and improvement of the performance/power ratio. The Moore’s Law is inherently the law for the technology and economic development, and has served as the guideline of the IC development for half a century. However, with the scaling down of IC feature size and the corresponding increased integration density, it is progressively approaching the physical limitation. Moore’s Law will gradually complete its historic mission and it will be replaced by a law of reducing the power consumption while ensuring the performance requirements for IC, SoC and SiP performance, law of improving the performance/power ratio. This paper will discuss the related research topics on Green micro/nanoelectronics, including low-power design, novel low-power devices, manufacturing processes for low power applications and related micro/nano electromechanical systems.

关键词： power consumption IC technology

A multiple user sharing behaviors based approach for fake file detection in P2P environments

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science china(Information sciences) 2010年第11期53卷 2169-2184页

作者： JIANG Jing, LI YongJun, FENG QinYuan, HUANG Peng & DAI YaFei Department of computer science and technology, peking university, beijing 100871, china Department of computer science and technology Peking University Beijing China

File pollution is a problem that is threatening security and availability in peer-to-peer environments, and could eventually be fatal to the survival of these systems. Current methods of fake file detection, which are based on trust mechanisms or file characteristics, do not consider the problems such as interference of multiple user sharing behaviors, the difficulty in obtaining large amounts of raw data, and malicious fraud immediately after version publication. This is the first time that differences in the sharing habits of users and particularly long retention time for individual files have been detected, which impact fake file detection. This paper proposes a pollution prevention model based on multiple user sharing behaviors, which reduces interference in multiple user sharing behaviors and malicious fraud immediately after version publication. It designs a low-cost implementation mechanism for use in structured peer-to-peer networks, which automatically collects a large amount of user file-sharing information and alleviates difficulties in obtaining large quantities of raw data. A parameter configuration is also given in this paper. Simulation experiments use realistic system logs and prove that this approach detects fake files accurately and quickly, thus decreasing download times of fake files, effectively guaranteeing almost 100% real file downloads and resisting file pollution.

关键词： peer-to-peer file pollution user sharing behavior

SUPERCONVERGENCES OF THE ADINI'S ELEMENT FORSECOND ORDER EQUATION

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Journal of Computational Mathematics 1999年第6期17卷 569-574页

作者： Ping Luo(Department of computer science and technology, Qinghua university, beijing 100084,china)Qun Lin(institute of Systems science, Academia Sinica, beijing, 100080, china) 清华大学计算机系北京 100084 中科院系统科学所北京 100080

n this papers the asymptotic error expansions of Adini's element for the secondorder imhomogeneous Neumann problem are given and the superconvergence estimations are obtained. Moreover, a numerical example to support ... 详细信息

关键词： Adini's element Superconvergence estimation Asymptotic expansion.