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Journal of Hydrodynamics 2011年第3期23卷 282-288页

作者： LIU Nan-sheng CHENG Bao-guo QUE Xia LU Xi-yun department of Modem Mechanics University of Science and Technology of China Hefei 230026 China department of computer {2. and technology Hefei University of Technology Hefei 230009 China

Turbulent channel flows with consideration of the buoyancy effect of the bubble phase is investigated by means of the Direct Numerical Simulation （DNS）. This two-phase system is solved by a two-way coupling Lagrangian-Eulerian approach. The Reynolds number based on the friction velocity and the half-width of the channel is 194, and the gravitational acceleration varies from -0.5 to 0.5, ranging from the upflow to the downflow cases. This study aims to reveal the influence of buoyancy on the turbulence behavior and the bubble motion. Some typical statistical quantities, including the averaged velocities and velocity fluctuations for the fluid and bubble phases, as well as the flow structures of the turbulence fluctuations, are analyzed.

关键词： Direct Numerical Simulations (DNS) turbulent bubbly flow upflow/downflow turbulence fluctuations bubble statistics turbulence structures

Tissue P systems with cell separation: attacking the partition problem

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science china(Information sciences) 2011年第2期54卷 293-304页

作者： ZHANG XingYi1, WANG Shuo2. NIU YunYun2.& PAN LinQiang2.1Key Lab of Intelligent Computing and Signal Processing of Ministry of Education, School of computer science and {2., Anhui university, Hefei 2.0039, china 2.mage Processing and Intelligent Control Key Laboratory of Education Ministry of china, department of Control science and Engineering, Huazhong university of science and {2., Wuhan 430074, china 1. Key Lab of Intelligent Computing and Signal Processing of Ministry of Education School of Computer Science and Technology Anhui University Hefei 230039 China2. Image Processing and Intelligent Control Key Laboratory of Education Ministry of China Department of Control Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

Tissue P systems are distributed parallel and non-deterministic computing models in the framework of membrane computing, which are inspired by intercellular communication and cooperation between neurons. Recently, cell separation is introduced into tissue P systems, which enables systems to generate an exponential workspace in a polynomial time. In this work, the computational power of tissue P systems with cell separation is investigated. Specifically, a uniform family of tissue P systems with cell separation is constructed for effciently solving a well-known NP-complete problem, the partition problem.

关键词： membrane computing tissue P system cell separation partition problem

Dynamic spreading behavior of homogeneous and heterogeneous networks

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Progress in Natural science:Materials International 2007年第3期17卷 358-365页

作者： XIA Chengyi, LIU Zhongxin, CHEN Zengqiang and YUAN Zhuzhi ( department of Automation, Nankai university, Tianjin 300071, {2. department of computer science and Engineering, Tian-jin university of technology, Tianjin 300191, {2.) [a]department of Automation Nankai University Tianjin China [b]department of computer {2. and Engineering Tianjin University of Technology Tianjin China

The detailed investigation of the dynamic epidemic spreading on homogeneous and heterogeneous networks was carried out. After the analysis of the basic epidemic models, the susceptible-infected-susceptible (SIS) model on homogenous and heterogeneous networks is established, and the dynamical evolution of the density of the infected individuals in these two different kinds of networks is analyzed theoretically. It indicates that heterogeneous networks are easier to propagate for the epidemics and the leading spreading behavior is dictated by the exponential increasing in the initial outbreaks. Large-scale simulations display that the infection is much faster on heterogeneous networks than that on homogeneous ones. It means that the network topology can have a significant effect on the epidemics taking place on complex networks. Some containment strategies of epidemic outbreaks are presented according to the theoretical analyses and numerical simulations.

关键词： complex networks dynamic epidemic spreading SIS model homogeneous networks heterogeneous networks containment strategies.

Partitioning series-parallel multigraphs into υ*-excluding edge covers

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science china Mathematics 2006年第8期49卷 1082-1093页

作者： LIU Guizhen, DENG Xiaotie & XU Changqing School of Mathematics and System science, Shandong university, Jinan 2.0100, {2. department of computer science, City university of Hong Kong, Kowloon, Hong Kong, {2. department of Applied Mathematics, Hebei university of technology, Tianjin 300130, {2. School of Mathematics and System science Shandong University Jinan 250100 China department of computer {2. City University of Hong Kong Kowloon Hong Kong Hong Kong department of Applied Mathematics Hebei University of Technology Tianjin 300130 China

We prove that, for any given vertexν* in a series-parallel graph G, its edge set can be partitioned into k= min{k′(G) + 1,δ(G)} subsets such that each subset covers all the vertices of G possibly except forν*, whereδ(G) is the minimum degree of G and k′(G) is the edge-connectivity of G. In addition, we show that the results in this paper are best possible and a polynomial time algorithm can be obtained for actually finding such a partition by our proof.

关键词： series-parallel graph, edge-connectivity, edge cover coloring, min-max theorem.

Superconductivity of small metal grains

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science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 431-441页

作者： ZHENG Renrong1 CHEN Zhiqian2.& ZHU Shunquan1,3 1. department of Physics, Shanghai Normal university, Shanghai 2.02.4, {2. 2. department of Physics, Southwest Normal university, Chongqing 400715, {2. 3. department of computer and Electric technology, Shanghai Business School, Shanghai 2.1400, {2. 1. department of Physics Shanghai Normal University 200234 Shanghai China 2. department of Physics Southwest Normal University 400715 Chongqing China 3. department of computer and Electric {2. Shanghai Business School 201400 Shanghai China

The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.

关键词： size effect, superconductivity enhancements, small metallic grains.

The construction of infinite families of any k-tight optimal and singular k-tight optimal directed double loop networks

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science china Mathematics 2007年第7期50卷 1055-1064页

作者： Bao-xing CHEN~(1+) Xie-bin CHEN~2.Ji-xiang MENG~3 Wen-jun XIAO~4 1 department of computer {2.,Zhangzhou Teachers College,Zhangzhou 363000,china 2.department of Mathematics and Information {2.,Zhangzhou Teachers College,Zhangzhou 363000,china 3 College of Mathematics & System {2.,Xinjiang university,Urumqi 830046,china 4 department of computer {2.,South china university of technology,Guangzhou 510641,china 1. department of computer {2. Zhangzhou Teachers College Zhangzhou 363000 China 2. department of Mathematics and Information science Zhangzhou Teachers College Zhangzhou 363000 China 3. College of Mathematics & System science Xinjiang University Urumqi 830046 China 4. department of computer {2. South China University of Technology Guangzhou 510641 China

The double loop network(DLN)is a circulant digraph with n nodes and outdegree *** is an important topological structure of computer interconnection networks and has been widely used in the designing of local area networks and distributed *** the number n of nodes,how to construct a DLN which has minimum diameter?This problem has attracted great attention.A related and longtime unsolved problem is:for any given non-negative integer k,is there an infinite family of k-tight optimal DLN?In this paper,two main results are obtained:(1)for any k≥0,the infinite families of k-tight optimal DLN can be constructed,where the number n(k,e,c)of their nodes is a polynomial of degree 2.in e with integral coefficients containing a parameter c.(2.for any k≥0, an infinite family of singular k-tight optimal DLN can be constructed.

关键词： double loop network diameter k-tight optimal singular k-tight optimal 05C12 05C2. 05C85

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Lp shape deformation

science china(Information sciences) 2012年第5期55卷 983-993页

作者： GAO Lin1,ZHANG GuoXin 1 & LAI YuKun 2.1 department of computer {2. and technology,Tsinghua university,Beijing 100084,china 2.School of computer {2. and Informatics,Cardiff university,Wales CF2. 3AA,UK 1. department of computer {2. and technology Tsinghua University Beijing 100084 China2. School of Computer Science and Informatics Cardiff University Wales CF24 3AA UK

Shape deformation is a fundamental tool in geometric *** methods consider preserving local details by minimizing some energy functional measuring local distortions in the L 2.*** strategy distributes distortions quite uniformly to all the vertices and penalizes ***,there is no unique answer for a natural deformation as it depends on the nature of the *** by recent sparse signal reconstruction work with non L 2.norm,we introduce general L p norms to shape deformation;the positive parameter p provides the user with a flexible control over the distribution of unavoidable *** with the traditional L 2.norm,using smaller p,distortions tend to be distributed to a sparse set of vertices,typically in feature regions,thus making most areas less distorted and structures better *** the other hand,using larger p tends to distribute distortions more evenly across the whole *** flexibility is often desirable as it mimics objects made up with different *** specifying varying p over the shape,more flexible control can be *** demonstrate the effectiveness of the proposed algorithm with various examples.

关键词： shape deformation Lp norm geometric modeling

ANALYSIS AND MEASUREMENT OF LARGE DYNAMIC RANGE RF SWITCH INTER-MODULATION

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Journal of Electronics(china) 2008年第3期25卷 422-427页

作者： Han Zhouan department of Electronic Engineering the University of Electronic Science and Technology Chengdu 610054 China

Radio Frequency (RF) switch circuit is the basic part of microwave devices and systems. The non-linearity distortion figure is necessary in the field of large dynamic range of signal. This letter analyzes the basic switch circuit and its inter-modulation, and studies in detail the measurement methods and systems of RF switch intercept point. It has provided cascaded simulation testing methods, which can accurately measure the PF switch, of which the second or third order intercept point value is above 75dB and 60dB, respectively. As the testing results are consistent with the theoretical analyses, it proves that the validity of the method satisfies the requirements of large scaled linearity measurement in engineering.

关键词： Large dynamic range Radio Frequency (RF) switch Intercept point Measurement

Shape Memory Effect of As-aged Fe-14Mn-5Si-8Cr-4Ni-0.2. Alloy

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Journal of Materials science & technology 2000年第4期16卷 424-426页

作者： Yuhua WEN, Ning LI and Mingjing TU (department of Materials Shaping and Controlling Engineering, Sichuan university, {2. 610065, china) department of Materials Shaping and Controlling Engineering Sichuan University Chengdu 610065 China

The effects of aging temperature on shape memory effect, mechanical properties and microstruc-ture of Fe-14Mn-5Si-8Cr-4Ni-0.2. shape memory alloy have been studied. The results showed that the second phase particles rich in chromium, manganese and silicon precipitate during aging, and thereby increase the hardness and strength of the alloy. The shape recovery ratio can be remarkably improved by aging and a maximum value can be obtained at 12.3 K, which is 68% higher than that of the specimen in solid solution state. When the aging temperature is below 12.3 K, the amount of second phase particles increases as the aging temperature increases. The size of austenite grain increases with increasing aging temperature. When the temperature is over 12.3 K, the second phase particles can not precipitate. The lack of second phase particles and the increase of grain size make the hardness and shape recovery ratio drastically decrease, when the temperature is over 12.3 K.

关键词： Mn Shape Memory Effect of As-aged Fe-14Mn-5Si-8Cr-4Ni-0.2. Alloy As Fe Cr Ni Si

Towards a Methodology for Formal Design and Analysis of Agent Interaction Protocols ——An Investigation in Electronic Commerce

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Wuhan university Journal of Natural sciences 2001年第Z1期6卷 126-139页

作者： Wei Jun 1,2., Cheung Shing Chi 1, Wang Xu 1 1. department of computer {2., Hong Kong university of {2. and technology, Clear Water Bay, Kowloon, Hong Kong, china 2. Institute of Software, Chinese Academy of {2., Beijing 100080, Ch department of computer {2. Hong Kong University of Science and Technology Kowloon Hong Kong China Institute of Software Chinese Academy of Science Beijing China

Various extensions of UML have been developed to meet the challenges of designing modern software systems, such as agent based electronic commerce applications. Recent advances in model checking technology have led it to be introduced into the development of approaches and tools to check the correctness of electronic commerce protocols. This paper focuses on the research of a method that connects an extension of AUML to model checker SPIN/Promela for the specification and verification of agent interaction protocols (AIP) in electronic commerce. The method presented here allows us to combine the benefits of visual specification with the power of some static analysis and model checking. Some algorithms and rules are developed to permit all visual modeling constructs translated mechanically into some Promela models of AIP, as supported by the model checker SPIN. Moreover, a process is illustrated to guide the specification and verification of AIP. The method is demonstrated thoroughly using the e commerce protocol NetBill as an example.

关键词： agent UML interaction protocol software agent model checking formal specification electronic commerce protocol