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AN EFFICIENT MOVING MESH METHOD FOR A MODEL OF TURBULENT FLOW IN CIRCULAR TUBES

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Journal of computational mathematics 2009年第Z1期 388-399页

作者： Yin Yang hunan key laboratory for computation and simulation in science and engineering,School of mathematics and computational science,xiangtan university,xiangtan 411105,china Yanping Chen School of Mathematical sciences,South china Normal university,Guangzhou,china Yunqing Huang hunan key laboratory for computation and simulation in science and engineering,School of mathematics and computational science,xiangtan university,xiangtan 411105,china

This paper presents an efficient moving mesh method to solve a nonlinear singularproblem with an optimal control constrained *** physical problem is governedby a new model of turbulent flow in circular tubes proposed by Luo et *** Prandtl’smixing-length *** algorithm is formed by an outer iterative algorithm for handlingthe optimal control condition and an inner adaptive mesh redistribution algorithm forsolving the singular governing *** discretize the nonlinear problem by using aupwinding approach,and the resulting nonlinear equations are solved by using the Newton-Raphson *** mesh is generated and the grid points are moved by using thearc-length equidistribution *** numerical results demonstrate that proposedalgorithm is effective in capturing the boundary layers associated with the turbulent model.

关键词： Eddy viscosity Turbulent pipe flow Boundary layer Optimal control Moving mesh

Preconditioners for higher order edge finite element discretizations of Maxwell's equations

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science china mathematics 2008年第8期51卷 1537-1548页

作者： ZHONG LiuQiang1,2,SHU Shi1,2,SUN DuDu3&TAN Lin4 1School of Mathematical and computational sciences,xiangtan university,xiangtan 411105,china 2hunan key laboratory for computation and simulation in science and engineering,xiangtan 411105,china 3institute of computational mathematics and Scientific/engineering Computing,Academy of mathematicsand Systems science,Graduate university of Chinese Academy of sciences,Chinese Academy sciences,P.O.Box 2719,Beijing 100190,china 4Department of Math-Physics,Nanhua university,Hengyang 421001,china School of Mathematical and computational sciences Xiangtan University Xiangtan China hunan key laboratory for computation and simulation in science and engineering Xiangtan China institute of computational mathematics and Scientific/engineering Computing Academy of Mathematics and Systems Science Graduate University of Chinese Academy of Sciences Chinese Academy Sciences Beijing China Department of Math-Physics Nanhua University Hengyang China

In this paper,we are concerned with the fast solvers for higher order edge finite element discretizations of Maxwell's *** present the preconditioners for the first family and second family of higher order N′ed′elec element equations,*** combining the stable decompositions of two kinds of edge finite element spaces with the abstract theory of auxiliary space preconditioning,we prove that the corresponding condition numbers of our preconditioners are uniformly bounded on quasi-uniform *** also present some numerical experiments to demonstrate the theoretical results.

关键词： preconditioner higher order edge finite element stable decomposition

Analysis theory of random energy of train derailment in wind

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science china(Physics,Mechanics & Astronomy) 2010年第4期53卷 751-757页

作者： CHEN RuiLin 1,2,3 , ZENG QingYuan 3 , HUANG YunQing 1 , XIANG Jun 3 , WEN Ying 3 , GUO XiaoGang 2 , YIN ChangJun 2 , DONG Hui 2 & ZHAO Gang 4 1 hunan key laboratory for computation and simulation in science and engineering, xiangtan university, xiangtan 411105, china 2 School of Civil engineering & Mechanics, xiangtan university, xiangtan 411105, china 3 School of Civil Architecture, Central South university, Changsha 410075, china 4 AMEC, Toronto M5A5G7, Canada hunan key laboratory for computation and simulation in science and engineering Xiangtan University Xiangtan China School of Civil engineering & Mechanics Xiangtan University Xiangtan China School of Civil Architecture Central South University Changsha China AMEC Toronto Canada

Based on the analysis theory of random energy of train derailment, an analysis theory of random energy of train derailment in wind is suggested. Two methods are proposed -the time domain method and the frequency domain method of analysis theory of random energy of train derailment in wind. The curves of σ pw -v under various wind speeds are obtained through the computation. The original curve of σ p -v is expanded, which turns the analysis theory of random energy of train derailment into the all-weather theory. Train derailment condition has been established under wind action. The first and second criterions of train derailment have been proposed in light of wind action. The analysis of train derailment cases at home or abroad is made, in- cluding the first analysis of Xinjiang train derailment case encountered 13-level of gale, which explained the inevitability of train derailment. The analysis theory of random energy of train derailment in wind shows its validity and accuracy. The input energy σ pw of the transverse vibration of train-track(bridge)-wind system is linked to train speed. With the establishment of the analysis theory of random energy of train derailment in wind, It is likely to initiate an all-weather speed limit map for a train or any high-speed train.

关键词： train derailment analysis theory of random energy of train derailment analysis theory of random energy of train de- railment in wind train derailment condition in wind the criterion of train derailment in wind train derailment case

Total control-based unified allocation model for allowable basin water withdrawal and sewage discharge

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science china(Technological sciences) 2010年第5期53卷 1387-1397页

作者： HU SiYi1,2,WANG ZongZhi1,WANG YinTang1 & ZHANG LingLing3 1 State key laboratory of Hydrology-Water Resources and Hydraulic engineering,Nanjing Hydraulic Research institute,Nanjing 210029,china 2 Ministry of Water Resources,the People’s Republic of china,Beijing 100053,china 3 School of Public Administration,HoHai university,Nanjing 210098,china State key laboratory of Hydrology-Water Resources and Hydraulic engineering Nanjing Hydraulic Research Institute Nanjing China Ministry of Water Resources the People’s Republic of China Beijing China School of Public Administration HoHai University Nanjing China

In this paper,a new model with a total amount control target of allowable water withdrawal based on initial water right is built for the implementation of initial water right allocation scheme as well as unified allocation for allowable water withdrawal and sewage *** model couples the water allocation simulation model and the computational model of permissible pol-lution bearing *** view of the model complexity,a new technology which synthesizes system simulation,iterative reservoir turns and intelligent computation is proposed to improve the operability of allocation scheme and computational *** the Beijiang River Basin in the Pearl River Basin as an example,the study explains the model establishment,solution and application,and draws an optimized operation graph of large-scale *** study also obtains a long-term operation strategy of river basin water resources system,the allocation schemes of allowable water withdrawal and sewage discharge in a typical year and the flow hydrographs of trans-boundary *** validity of the model and the allocation rationality are analyzed as well.

关键词： water resources management total control unified control of water withdrawal and sewage discharge optimized regulation integration technology

Study on optimization of agent initial positions in land combat simulation

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Progress in Natural science:Materials International 2004年第3期 65-69页

作者： WU Chunguo 1,2 , LIANG Yanchun* 1, 2 , LEE Heow Pueh 2, LU Chun 2 and YANG Xiaowei 3,4 (1. College of Computer science and Technology, key laboratory of Symbol computation and Knowledge engineering of the Ministry of Education, Jilin university, Changchun 130012, china 2. institute of High Performance Computing, Singapore 117528, Singapore 3. Department of applied mathematics, South china university of Technology, Guangzhou 510640, china 4. Centre for ACES, Department of Mechanical engineering, National university of Singapore, 119260, Singapore) CollegeofComputerscienceandTechnology KeyLaboratoryofSymbolComputationandKnowledgeEngineeringoftheMinistryofEducationJilinUniversityChangchun130012China InstitiuteofHighPerformanceComputing Singapore117528Singapore Departmentofappliedmathematics SouthChinaUniversityofTechnologyGuangzhou510640China

The use of computational intelligence based techniques in the optimization of agent initial positions in land combat simulations is studied. A novel method for the reduction of support vectors in the support vector machine (SVM) is presented. The optimization on the width of the Gaussian kernel function and the combination of the SVM with the radial basis function neural network are performed in the proposed method. simulation results show that the proposed method can improve the running efficiency drastically compared with that using the traditional SVM with the same precision. We also summarize and present some experiences and trends in the study on the optimization problem in land combat simulation.

关键词： multi agent support vector machine radial basis function genetic algorithm regression.

computation of the Viscous Hydrodynamic Forces on a KVLCC2 Model Moving Obliquely in Shallow Water

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Journal of Shanghai Jiaotong university(science) 2009年第2期14卷 241-244页

作者：王化明邹早建田喜民 School of Naval Architecture Ocean and Civil EngineeringShanghai Jiaotong University State key laboratory of Ocean engineering Shanghai Jiaotong University

The viscous hydrodynamic force and moment on ships moving obliquely in shallow water are important for ship navigation *** the paper,the viscous flow field around a KVLCC2 model moving obliquely in shallow water is simulated and the hydrodynamic drag,lateral force and yaw moment acting on the hull are obtained by a general purpose computational fluid dynamics(CFD) package FLUENT with shear-stress transport(SST) k—ωturbulence *** numerical computation is performed at different drift angels and water *** numerical results are compared with experimental results,and a good agreement is demonstrated.

关键词： oblique motion shallow water viscous flow hydrodynamic forces numerical simulation

MEG inversion using spherical head model combined with brain-shaped head model

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Chinese Journal of Biomedical engineering(English Edition) 2001年第1期10卷 20-26页

作者： LI Jun State key laboratory of Modern Optical Instrumentation, Center for Optical and Electromagnetic Research, College of Information science and engineering, Zhejiang university, Hangzhou 310027, china State key laboratory of Modern Optical Instrumentation Center for Optical and Electromagnetic Research College of Information Science and EngineeringZhejiang University Hangzhou 310027 China

The spherical head model has been widely used in magnetoencephalography (MEG) as a simple forward model for calculating the external magnetic field producing by neural currents in a human brain. But this model may lead to an inaccurate result, even if the computation speed is fast. For more precise computation, realistic brain-shaped head model is used with the boundary element method (BME), but at greatly increased computational cost. When solving MEG inverse problem by using optimization methods, the forward problem must often be solved for thousands of possible source configurations. So if the brain-shaped head model is used in all iterative steps of optimization, it may be computationally infeasible for practical application. In this paper, we present a method about using compound head model in MEG inverse solution. In this method, first spherical head model is used for a rough estimation, then brain-shaped head model is adopted for more precise solution. Numerical simulation indicates that under the condition of same accuracy, the computation speed for the present method is about three times faster than a method using the brain-shaped head model at all iterations.

关键词： Magnetoencephalography (MEG), Boundary element method, In verse problem, Optimization

Memetic computation based on regulation between neural and immune systems: the framework and a case study

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science china(Information sciences) 2010年第8期53卷 1519-1527页

作者： GONG MaoGuo , JIAO LiCheng, LIU Fang & YANG Jie key Lab of Intelligent Perception and Image Understanding of Ministry of Education of china, institute of Intelligent Information Processing, Xidian university, Xi’an 710071, china key Lab of Intelligent Perception and Image Understanding of Ministry of Education of china Institute of Intelligent Information Processing Xidian University Xi’an China

Lamarckian learning has been introduced into evolutionary computation to enhance the ability of local search. The relevant research topic, memetic computation, has received significant amount of interest. In this study, a novel memetic computational framework is proposed by simulating the integrated regulation between neural and immune systems. The Lamarckian learning strategy of simulating the unidirectional regulation of neural system on immune system is designed. Consequently, an immune memetic algorithm based on the Lamarckian learning is proposed for numerical optimization. The proposed algorithm combines the advantages of immune algorithms and mathematical programming, and performs well in both global and local search. The simulation results based on ten low-dimensional and ten high-dimensional benchmark problems show that the immune memetic algorithm outperforms the basic genetic algorithm-based memetic algorithm in solving most of the test problems.

关键词： memetic computation artificial immune system Lamarckian learning genetic algorithm numerical optimization

Modeling and Generating Realistic Background Traffic by Hybrid Approach

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china Communications 2015年第10期12卷 147-157页

作者： QIAN Yaguan GUAN Xiaohui JIANG Ming CEN Gang School of science Zhejiang University of Science and Technology Zhejiang university of Water Resources and Electric Power College of Computer science Hang Zhou Dianzi University School of Information and Electronic engineering Zhejiang University of Science and Technology

One of the key challenges in largescale network simulation is the huge computation demand in fine-grained traffic *** from using high-performance computing facilities and parallelism techniques,an alternative is to replace the background traffic by simplified abstract models such as fluid *** paper suggests a hybrid modeling approach for background traffic,which combines ON/OFF model with TCP *** ON/OFF model is to characterize the application activities,and the ordinary differential equations(ODEs) based on fluid flows is to describe the TCP congestion avoidance *** apparent merits of this approach are(1) to accurately capture the traffic self-similarity at source level,(2) properly reflect the network dynamics,and(3) efficiently decrease the computational *** experimental results show that the approach perfectly makes a proper trade-off between accuracy and complexity in background traffic simulation.

关键词： network simulation background traffic ON/OFF models fluid flows self-similarity