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HIGH-RESOLUTION SEMI-DISCRETE CENTRAL SCHEME FOR DAM-BREAK PROBLEMS

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Journal of Hydrodynamics 2005年第5期17卷 585-589页

作者： CHEN Jian-zhong shi zhong-ke College of Automation Northwestern Polytechnical University Xi＇an 710072 China

A numerical model for simulating the dambreak problems was presented. The model was based on a high-resolution semi-discrete central-upwind difference scheme. In order to reduce spurious oscillation, the uniformly non-oscillatory limiter was employed. A third-order total variation diminishing Runge-Kutta method is used for time integration. The main feature of the presented method is its simplicity. It requires no Riemann solvers, no flux splitting and no flux limiter. It is explicit and does not require dimensional splitting for two dimensions. The Simpson quadrature rule was employed to compute the source term. To verify the effectiveness and accuracy of the proposed method, the 1D dambreak, circular dam-break and partial dam-break problems were simulated. The results are shown to be in good agreement with analytical solution and numerical results obtained by other methods.

关键词： dam-break shallow water equations central-upwind difference scheme

Weakly Compact Sets and Riesz Representation Theorem in Musielak Sequence Spaces

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Acta Mathematica Sinica,English Series 2024年第2期40卷 467-484页

作者： Wan zhong GONG Si Yu shi zhong Rui shi Department of Mathematics Anhui Normal UniversityWuhu 241000P.R.China Smeal College of Business Pennsylvania State UniversityUniversity ParkPennsylwania 16802USA Department of Mathematics Shanghai UniversityShanghai 200444P.R.China

In this work,we give some criteria of the weakly compact sets and a representation theorem of Riesz's type in Musielak sequence spaces using the ideas and techniques of sequence spaces and Musielak ***,as an immediate consequence of the criteria considered in this paper,the criteria of the weakly compact sets of Orlicz sequence spaces are deduced.

关键词： Compact set weak topology Banach space dual space Musielak sequence spaces

SOLUTION OF 2D SHALLOW WATER EQUATIONS BY GENUINELY MULTIDIMENSIONAL SEMI-DISCRETE CENTRAL SCHEME

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Journal of Hydrodynamics 2006年第4期18卷 436-442页

作者： CHEN Jian-zhong, shi zhong-ke College of Automation Northwestern Polytechnical University Xi＇an 710072 China

A numerical two-dimensional shallow water method was based on method for solving the equations was presented. This the third-order genuinely multidimensional semi-discrete central scheme for spatial discretization and the optimal third-order Strong Stability Preserving （SSP） Runge-Kutta method for time integration. The third-order compact Central Weighted Essentially Non-Oscillatory （CWENO） reconstruction was adopted to guarantee the non-oscillatory behavior of the presented scheme and improve the resolution. Two kinds of source terms were considered in this work. They were evaluated using different approaches. The resulting scheme does not require Riemann solvers or characteristic decomposition, hence it retains all the attractive features of central schemes such as simplicity and high resolution. To evaluate the performance of the presented scheme, several numerical examples were tested. The results demonstrate that our method is efficient, stable and robust.

关键词： 2D shallow water equations semi-discrete central scheme Central Weighted Essentially Non-Oscil]atory (CWENO) reconstruction

Recent progress in high temperature permanent magnetic materials

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Rare Metals 2013年第5期32卷 431-440页

作者： Cheng-Bao Jiang shi-zhong An School of Materials Science and Engineering Beihang University

Permanent magnetic materials capable of operating at high temperature up to 500℃ have wide potential applications in fields such as aeronautics, space, and electronic cars. SmCo alloys are candidates for high temperature applications, since they have large magnetocrystalline anisotropy field （6-30 T）, high Curie temperature （720-920℃）, and large energy product （〉200 kJ.m-3） at room temperature. However, the highest service temperature of commercial 2：17 type SmCo magnets is only 300℃, and many efforts have been devoted to develop novel high temperature permanent magnets. This review focuses on the development of three kinds of SmCo based magnets： 2：17 type SmCo magnets, nanocrystalline SmCo magnets, and nanocomposite SmCo magnets. The oxidation protection, including alloying and surface modification, of high temperature permanent magnets is discussed as well.

关键词： Magnetic materials Sm-Co alloys Permanent magnets High temperature

CONSTRAINED QUADRILATERAL NONCONFORMING ROTATED Q1 ELEMENT

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Journal of Computational Mathematics 2005年第6期23卷 561-586页

作者： Jun Hu zhong-ci shi LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China

In this paper, we define a new nonconforming quadrilateral finite element based on the nonconforming rotated Q1 element by enforcing a constraint on each element, which has only three degrees of freedom. We investigate the consistency, approximation, superclose property, discrete Green＇s function and superconvergence of this element. Moreover, we propose a new postprocessing technique and apply it to this element. It is proved that the postprocessed discrete solution is superconvergent under a mild assumption on the mesh.

关键词： Constrained Nonconforming Rotated Q1 element Superconvergence Postprocess

A NOTE ON THE QUADRILATERAL MESH CONDITION RDP(N,ψ)

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Journal of Computational Mathematics 2007年第1期25卷 27-30页

作者： Dongyang shi zhong-Ci shi Jingzhu Wu Department of Mathematics Zhengzhou University Zhengzhou 450052 China LSEC ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China

The main aim of this paper is to show that the quadrilateral mesh condition RDP（N, ψ） is only sufficient but not necessary for the optimal order error estimate of the Q isoparametric element in the Hi norm.

关键词： Isoparametric finite element Optimal order error estimate Quadrilateral meshcondition.

α-clustering effect on flows of direct photons in heavy-ion collisions

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Nuclear Science and Techniques 2021年第6期32卷 122-132页

作者： Chen-zhong shi Yu-Gang Ma Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China University of the Chinese Academy of Sciences Beijing 100080China

In this study,we reconstruct theγ-photon energy spectrum,which is in good agreement with the experimental data of ^(86)Kr+^(12)C at E/A=44 Me V within the framework of the modified EQMD *** directed and elliptic flows of free protons and direct photons were investigated by considering theα-clustering structure of ^(12)*** with free protons,direct photon flows provide clearer information about the early stage of a nuclear *** difference in the collective flows between different configurations of ^(12)C is observed in this *** indicates that the collective flows of direct photons are sensitive to the initial ***,theγbremsstrahlung process might be taken as an alternative probe to investigate theα-clustering structure in a light nucleus from heavy-ion collisions within the Fermienergy region.

关键词： Nuclear reaction Direct photon Collective flow α-clustering configuration

A relaxation scheme for a multi-class Lighthill-Whitham-Richards traffic flow model

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第12期10卷 1835-1844页

作者： Jian-zhong CHEN zhong-ke shi Yan-mei HU College of Automation Northwestern Polytechnical University Xi 'an 710072 China College of Science Chang 'an University Xi 'an 710064 China

We present a high-resolution relaxation scheme for a multi-class Lighthill-Whitham-Richards (MCLWR) traffic flow model. This scheme is based on high-order reconstruction for spatial discretization and an implicit-explicit Runge-Kutta method for time integration. The resulting method retains the simplicity of the relaxation schemes. There is no need to involve Riemann solvers and characteristic decomposition. Even the computation of the eigenvalues is not required. This makes the scheme particularly well suited for the MCLWR model in which the analytical expressions of the eigenvalues are difficult to obtain for more than four classes of road users. The numerical results illustrate the effectiveness of the presented method.

关键词： Relaxation scheme Multi-class LWR model Traffic flow CWENO reconstruction Implicit-explicit Runge-Kutta

P1-NONCONFORMING QUADRILATERAL FINITE VOLUME ELEMENT METHOD AND ITS CASCADIC MULTIGRID ALGORITHM FOR ELLIPTIC PROBLEMS

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Journal of Computational Mathematics 2006年第1期24卷 59-80页

作者： Hong-ying Man zhong-ci shi LSEC ICMSEC Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing 100080 China Department of Mathematics Beijing institute of Technology Beijing 100081 China

In this paper, we discuss the finite volume element method of P1-nonconforming quadrilateral element for elliptic problems and obtain optimal error estimates for general quadrilateral partition. An optimal cascadic multigrid algorithm is proposed to solve the non-symmetric large-scale system resulting from such discretization. Numerical experiments are reported to support our theoretical results.

关键词： finite volume element method cascadic multigrid Elliptic problems