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Improvement on Spherical Symmetry in Two-Dimensional Cylindrical Coordinates for a Class of Control Volume Lagrangian Schemes

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Communications in Computational Physics 2012年第4期11卷 1144-1168页

作者： Juan Cheng chi-Wang shu Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China Division of Applied Mathematics Brown UniversityProvidenceRI 02912USA

In[14],Maire developed a class of cell-centered Lagrangian schemes for solving Euler equations of compressible gas dynamics in cylindrical *** schemes use a node-based discretization of the numerical *** control volume version has several distinguished properties,including the conservation of mass,momentum and total energy and compatibility with the geometric conservation law(GCL).However it also has a limitation in that it cannot preserve spherical symmetry for one-dimensional spherical *** alternative is also given to use the first order area-weighted approach which can ensure spherical symmetry,at the price of sacrificing conservation of *** this paper,we apply the methodology proposed in our recent work[8]to the first order control volume scheme of Maire in[14]to obtain the spherical symmetry *** modified scheme can preserve one-dimensional spherical symmetry in a two-dimensional cylindrical geometry when computed on an equal-angle-zoned initial grid,andmeanwhile itmaintains its original good properties such as conservation and *** two-dimensional numerical examples in cylindrical coordinates are presented to demonstrate the good performance of the scheme in terms of symmetry,non-oscillation and robustness properties.

关键词： Control volume Lagrangian scheme spherical symmetry preservation conservative cell-centered compressible flow cylindrical coordinates

A HIGH ORDER ADAPTIVE FINITE ELEMENT METHOD FOR SOLVING NONLINEAR HYPERBOLIC CONSERVATION LAWS

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Journal of Computational Mathematics 2011年第5期29卷 491-500页

作者： Zhengfu Xu Jinchao Xu chi-Wang shu Department of Mathematics Michigan State University East Lansing MI ~882~ USA Department of Mathematics Pennsylvania State University University Park PA 16802 USA Division of Applied Mathematics Brown University Providence RI 02912 USA

In this note, we apply the h-adaptive streamline diffusion finite element method with a small mesh-dependent artificial viscosity to solve nonlinear hyperbolic partial differential equations, with the objective of achieving high order accuracy and mesh efficiency. We compute the numerical solution to a steady state Burgers equation and the solution to a converging-diverging nozzle problem. The computational results verify that, by suitably choosing the artificial viscosity coefficient and applying the adaptive strategy based on a posterior error estimate by Johnson et al., an order of N^-3/2 accuracy can be obtained when continuous piecewise linear elements are used, where N is the number of elements.

关键词： Adaptive finite element Nonlinear hyperbolic conservation law.

Design of 10 MeV electron linear accelerator for space environment simulation

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Nuclear Science and Techniques 2024年第10期35卷 96-109页

作者： shu Zhang Cai meng Zu-Sheng Zhou Xiang He Jing-Ru Zhang Munawar Iqbal Zhan-Dong Zhang Bo-Wen Bai Yun-Long chi Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China University of chinese Academy of Sciences Beijing 100049China Institute of Special Environments Physical Sciences Harbin Institute of TechnologyShenzhen 518055China

A compact 10 MeV S-band irradiation electron linear accelerator(linac)was developed to simulate electronic radiation in outer space and perform electron irradiation effect tests on spacecraft materials and *** to the requirements of space environment simulation,the electron beam energy can be adjusted in the range from 3.5 to 10 MeV,and the average current can be adjusted in the range from 0.1 to 1 *** linac should be capable of providing beam irradiation over a large area of 1 m^(2) with a uniformity greater than 90% and a scanning rate of 100 Hz.A novel method was applied to achieve such a high beam scanning rate by combining a kicker and a scanning *** on this requirement,a design for the10 MeV linac is proposed with an RF power pulse repetition rate of 500 Hz;it includes a thermal cathode electron gun,a bunching-accelerating section,and a scanning transport *** detailed physical design and dynamic simulation results of the proposed 10 MeV electron linac are presented in this paper.

关键词： Electron linac Accelerating structure Beam scanning Beam homogenization Irradiation linac

Conservative Semi-Lagrangian Finite Difference WENO Formulations with Applications to the Vlasov Equation

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Communications in Computational Physics 2011年第9期10卷 979-1000页

作者： Jing-Mei Qiu chi-Wang shu Department of Mathematical and Computer Science Colorado School of MinesGoldenCO 80401USA Division of Applied Mathematics Brown UniversityProvidenceRI 02912USA

In this paper,we propose a new conservative semi-Lagrangian(SL)finite difference(FD)WENO scheme for linear advection equations,which can serve as a base scheme for the Vlasov equation by Strang splitting[4].The reconstruction procedure in the proposed SL FD scheme is the same as the one used in the SL finite volume(FV)WENO scheme[3].However,instead of inputting cell averages and approximate the integral form of the equation in a FV scheme,we input point values and approximate the differential form of equation in a FD spirit,yet retaining very high order(fifth order in our experiment)spatial *** advantage of using point values,rather than cell averages,is to avoid the second order spatial error,due to the shearing in velocity(v)and electrical field(E)over a cell when performing the Strang splitting to the Vlasov *** a result,the proposed scheme has very high spatial accuracy,compared with second order spatial accuracy for Strang split SL FV scheme for solving the Vlasov-Poisson(VP)*** perform numerical experiments on linear advection,rigid body rotation problem;and on the Landau damping and two-stream instabilities by solving the VP *** comparison,we also apply(1)the conservative SL FD WENO scheme,proposed in[22]for incompressible advection problem,(2)the conservative SL FD WENO scheme proposed in[21]and(3)the non-conservative version of the SL FD WENO scheme in[3]to the same test *** performances of different schemes are compared by the error table,solution resolution of sharp interface,and by tracking the conservation of physical norms,energies and entropies,which should be physically preserved.

关键词： Semi-Lagrangian methods finite difference/finite volume scheme conservative scheme WENO reconstruction Vlasov equation Landau damping two-stream instability

An altered CD8^(+) T cell epitope of insulin prevents type 1 diabetes in humanized NOD mice

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Cellular & Molecular Immunology 2019年第6期16卷 590-601页

作者： mengjun Zhang shufeng Wang Binbin Guo Gang meng chi shu Wenli Mai Qian Zheng Xiaoling Chen Yuzhang Wu Li Wang Department of Pharmaceutical Analysis College of PharmacyArmy Medical University(Third Military Medical University)400038 ChongqingChina Institute of Immunology PLA&Department of Immunology Army Medical University(Third Military Medical University)400038 ChongqingChina Department of Pathology Southwest HospitalArmy Medical University(Third Military Medical University)400038 ChongqingChina Function Center North Sichuan Medical College637100 NanchongSichuanChina

Autoreactive CD8^(+)T cells,which play an indispensable role inβcell destruction,represent an emerging target for the prevention of type 1 diabetes(T1D).Altered peptide ligands(APLs)can efficiently induce antigen-specific T cells anergy,apoptosis or shifts in the immune ***,we found that HLA-A*0201-restricted CD8^(+)T cell responses against a primaryβ-cell autoantigen insulin epitope InsB15–14 were present in both NOD.β2m *** NOD mice and T1D *** generated several APL candidates for InsB15–14 by residue substitution at the p6 *** H6F exhibited an inhibitory effect on mInsB1_(5–14)-specific CD8^(+)T cell responses in vitro.H6F treatment significantly reduced the T1D incidence,which was accompanied by diminished autoreactive CD8^(+)T cell responses to mInsB15-14,inhibited infiltration of CD8^(+)and CD4^(+)T cells in the pancreas and reduced pro-inflammatory cytokine production in pancreatic and splenic T cells in NOD.β2m^(null).HHD ***,H6F treatment significantly augmented a tiny portion of CD8^(+)CD25^(+)Foxp3^(+)T cells in the spleen and especially in the *** subset exhibited typical Treg phenotypes and required peptide-specific restimulation to exert immunosuppressive ***,this APL H6F may be a promising candidate with potential clinical application value for antigen-specific prevention of T1D.

关键词： Type 1 diabetes Altered peptide ligand CD8^(+)CD25^(+)Foxp3^(+)regulatory T cells InsB1_(5–14) NOD.β2m^(null).HHD mice

Improvement of Convergence to Steady State Solutions of Euler Equations with Weighted Compact Nonlinear Schemes

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Acta Mathematicae Applicatae Sinica 2013年第3期29卷 449-464页

作者： shu-hai ZHANG Xiao-gang DENG Mei-liang MAO chi-Wang shu State Key Laboratory of Aerodynamics China Aerodynamics Research and Development Center china Aerodynamics Research and Development Center Division of Applied Mathematics Brown UniversityProvidence

The convergence to steady state solutions of the Euler equations for weighted compact nonlinear schemes （WCNS） [Deng X. and Zhang H. （2000）, J. Comput. Phys. 165, 22–44 and Zhang S., Jiang S. and shu C.-W. （2008）, J. Comput. Phys. 227, 7294-7321] is studied through numerical tests. Like most other shock capturing schemes, WCNS also suffers from the problem that the residue can not settle down to machine zero for the computation of the steady state solution which contains shock waves but hangs at the truncation error level. In this paper, the techniques studied in [Zhang S. and shu. C.-W. （2007）, J. Sci. Comput. 31, 273–305 and Zhang S., Jiang S and shu. C.-W. （2011）, J. Sci. Comput. 47, 216–238], to improve the convergence to steady state solutions for WENO schemes, are generalized to the WCNS. Detailed numerical studies in one and two dimensional cases are performed. Numerical tests demonstrate the effectiveness of these techniques when applied to WCNS. The residue of various order WCNS can settle down to machine zero for typical cases while the small post-shock oscillations can be removed.

关键词： weighted compact schemes convergence to steady state solution nonlinear weights

Preparation of true solutions of monomeric amyloidogenic protein/peptide:A critical prerequisite for aggregation kinetic study

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Science china Chemistry 2012年第1期55卷 118-124页

作者： DIAO shu ZHAO Hong WANG WeiMao WU chi Department of Chemistry The Chinese University of Hong Kong Hong Kong China The Hefei National Laboratory of Physical Science at Microscale Department of Chemical physics The University of Science and Technology of China Hefei 230022 China

Our dynamic laser light scattering(LLS) study shows that the current widely used protocols of dissolving amyloidogenic protein/peptide do not really result in a true solution;namely,there always exist a trace amount of interchain aggregates,which greatly affect the association kinetics,partially explaining why different kinetics were reported even for a solution with identical protein and ***,using a combination of the conventional dissolution procedure and our newly developed ultra-filtration method,we have developed a novel protocol to prepare a true solution of amyloidogenic protein/peptide without any interchain *** resultant solutions remain in their monomeric state for at least one week,which is vitally important for further study of the very initial stage of the interchain association under the physiological conditions because more and more evidence suggests that it is those small oligomers rather than large fabric aggregates that are *** addition,this study shows that combining static and dynamic LLS can lead to more physical and microscopic information about the protein association instead of only the size distribution.

关键词： amyloidogenic protein/peptide laser light scattering monomer ultra-filtration

Managing International News-Agency Relations under the Guomindang： china＇s Central News Agency, Zhao Minheng, and Reuters, 1931-1945

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Frontiers of History in china 2015年第4期10卷 594-644页

作者： Sheng-chi shu Faculty of Asian and Middle Eastern Studies University of Cambridge Cambridge CB3 9DA UK

During the Nationalist Era, china dealt with its relatively weaker position in the global geopolitics of news communication by forging and managing strategic collaborations with the world＇s leading news agencies. This study analyzes the case of the bilateral contractual relationship between Reuters and the Guomindang （GMD） government＇s official news agency, the Central News Agency （CNA）. By doing so, the article reveals that in the course of developing useful cooperation with the leading international news agencies to open up inter-institutional and interpersonal channels and networks for disseminating the GMD government＇s official news and viewpoints abroad, the GMD government and CNA were also confronted with a growing necessity to manage and control protracted contentious, disputes, and even conflicts arising from the party-state＇s persistent attempts to assert news communication sovereignty. The study also highlights the vital role of Zhao Minheng （1904-61）--a US-educated chinese journalist in the employment of Reuters--as middleman in the CNA-Reuters relationship. Zhao＇s career provides us with an important means to analyze CNA＇s international news-agency relations from transnational and transcultural perspectives.

关键词： international news-agency relations international propaganda institution global geopolitics of news communication news gathering and dissemination news censorship and control middleman

RKDG Methods with Multi-resolution WENO Limiters for Solving Steady-State Problems on Triangular Meshes

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Communications on Applied Mathematics and Computation 2024年第3期6卷 1575-1599页

作者： Jun Zhu chi-Wang shu Jianxian Qiu State Key Laboratory of Mechanics and Control of Mechanical Structures and Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles(NUAA) MIITNanjing University of Aeronautics and AstronauticsNanjing 210016JiangsuChina Division of Applied Mathematics Brown UniversityProvidenceRI 02912USA School of Mathematical Sciences and Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific ComputingXiamen UniversityXiamen 361005FujianChina

In this paper, we design high-order Runge-Kutta discontinuous Galerkin (RKDG) methods with multi-resolution weighted essentially non-oscillatory (multi-resolution WENO) limiters to compute compressible steady-state problems on triangular meshes. A troubled cell indicator extended from structured meshes to unstructured meshes is constructed to identify triangular cells in which the application of the limiting procedures is required. In such troubled cells, the multi-resolution WENO limiting methods are used to the hierarchical L^(2) projection polynomial sequence of the DG solution. Through using the RKDG methods with multi-resolution WENO limiters, the optimal high-order accuracy can be gradually reduced to first-order in the triangular troubled cells, so that the shock wave oscillations can be well suppressed. In steady-state simulations on triangular meshes, the numerical residual converges to near machine zero. The proposed spatial reconstruction methods enhance the robustness of classical DG methods on triangular meshes. The good results of these RKDG methods with multi-resolution WENO limiters are verified by a series of two-dimensional steady-state problems.

关键词： RKDG method Steady-state problem Multi-resolution WENO limiter Triangular mesh Machine zero