用于全电磁粒子模拟的复杂建模及网格生成技术

 基于Open CASCADE开源的计算机辅助几何设计类库,给出了全电磁粒子模拟中复杂模型构建技术及网格生成技术。介绍了Open CASCADE软件的基本特点;给出了基于Open CASCADE进行自主研发的用于全电磁粒子模拟的复杂模型构建软件EasyEMModeling的设计思想、程序框架及已具备的功能;基于Open CASCADE中的射线与几何体的求交算法,给出了Yee网格中共形描述3维复杂模型的共形网格生成技术;最后,给出了验证实例,证实了共形网格生成方法的正确性及有效性。     

网格环境下基于本体的知识库模型研究

针对知识技术仪用于描述网格服务的可用性以及如何被发现、调度和进化的现状，在开放网格服务体系结构（OGSA）的基础上，给出了知识库本体的形式化定义，分析了构建知识库所需的本体，在此基础上提出了网格环境下知识库通用体系结构及基于语义适配器的存储模型，克服了Sesame仔储模刑在存储不同格式文件和本体方面所存在的小足，讨论了网格知识库的访问机制。     

二维三温热传导方程的并行自适应多重网格算法求解

3-T heat conduct equation including electron, ion and photon (radiation) temperatures can be used to approximately describe the energy broadcast across multimedia for radial flow dynamics and discover the energy swapping among photon,electron and ion. Owing to the strong nonlinear diffusion coefficients and energy swapping coefficients and strong discontinuous coefficients across media interfaces,this equation is difficult to be solved with high numerical resolution. Based on the parallel adaptive multigrid software framework UG on 2-D unstructured grid, this paper successfully solved such equation with high resolution by combining the finite volume implicit discretization scheme and parallel adaptive multigrid algorithm, and gained much significant results.     

HLLE++格式在高马赫数空腔流动模拟中的应用

空腔流动存在剪切层运动、涡脱落与破裂,以及激波与激波、激波与剪切层、激波与膨胀波和激波/涡/剪切层相互干扰等现象,流动非常复杂,特别是高马赫数(M>2)时,剪切层和激波更强,激波与激波干扰更严重,对数值格式的要求更高,既需要格式耗散小,对分离涡等有很高的模拟精度,又需要格式在激波附近具有较大的耗散,可以很好地捕捉激波,防止非物理解的出现。Roe和HLLC等近似Riemann解格式在高马赫数强激波处可能会出现红玉现象,而HLLE++格式大大改善了这种缺陷,在捕捉高超声速激波时避免了红玉现象的发生,同时还保持在光滑区域的低数值耗散特性。本文在结构网格下HLLE++格式的基础上,通过改进激波探测的求解,建立了基于非结构混合网格的HLLE++计算方法,通过无粘斜坡算例,验证了HLLE++格式模拟高马赫数流动的能力,并应用于高马赫数空腔流动的数值模拟,开展了网格和湍流模型影响研究,验证了方法模拟高马赫数空腔流动的可靠性和有效性。     

A sparse grid method for the Navier–Stokes equations based on hyperbolic cross

A sparse grid method for the time‐dependent Navier–Stokes equations based on hyperbolic cross approximation is considered in this article. Subsequent truncation of the associated series expansion results in a sparse grid discretization. Stability and convergence of the fully discrete sparse grid method are established. Finally, the numerical experiment is presented to show the effectiveness of this sparse grid method. Copyright © 2013 John Wiley & Sons, Ltd.     

Nanoparticle Size and Concentration Dependence of the Electroactive Phase Content and Electrical and Optical Properties of Ag/Poly(vinylidene fluoride) Composites

This paper describes the processing of silver‐nanoparticle‐doped poly(vinylidene fluoride). The effects of the concentration and size of the filler on the electroactive phase of the polymer and the optical and electrical properties are discussed. Spherical silver nanoparticles incorporated into the poly(vinylidene fluoride) polymeric matrix induce nucleation of the electroactive γ phase. The electroactive phase content strongly depends on the content and size of the nanoparticles. In particular, there is a critical nanoparticle size, below which the filler losses its nucleation efficiency due to its small size relative to that of the polymer macromolecules. Furthermore, the presence of surface plasmon resonance absorption in the composites is observed, which once again shows a strong dependence on the concentration and size of the particles. The absorption is larger for higher concentrations, and for a given concentration increases with particle size. This behavior is correlated to the electrical response and is related to the extra bands and electrons provided by the nanoparticles in the large energy band gap of the polymer.     

热智能材料及其在空间热控中的应用

空间技术等高新领域对智能高效的热控制技术的需求日益提高,而实现智能热控制技术的关键是要实现材料的热物性智能调控,于是热导率可响应外场变化的热智能材料成为了研究的焦点.本文梳理了热智能材料的最新研究进展,从调控机理、调控幅度、应用价值等角度出发,介绍了纳米颗粒悬浮液、相变材料、软物质材料、受电化学调控的层状材料和受特定外场调控的材料等不同种类热智能材料的研究现状,以及以热智能材料为基础的智能热控部件在空间技术等领域的应用.最后,本文对热智能材料未来的研究方向进行了探讨.     

Third-Order Nonlinear Integrated Device Based on an Effective Graded-Index Waveguide for All-Optical Multistability

We present a theoretical study of all-optical multistability in an integrated device composed by a step-index nonlinear Kerr waveguide with a variable width film, providing an effective graded-index profile. The self- and cross-action of nonlinear Gaussian counterpropagating beams in this structure and a feedback controlling mechanism based on transverse modal coupling generate a multistable behavior. The results have been obtained and explained on the basis of the exact solutions of the variational problem for the counterpropagating Gaussian beams. Finally, in order to make clear the possibilities of this device, novel applications of the all-optical multistable integrated device are proposed for smart sensing.     

Solution of the shallow‐water equations using an adaptive moving mesh method

This paper extends an adaptive moving mesh method to multi‐dimensional shallow water equations (SWE) with source terms. The algorithm is composed of two independent parts: the SWEs evolution and the mesh redistribution. The first part is a high‐resolution kinetic flux‐vector splitting (KFVS) method combined with the surface gradient method for initial data reconstruction, and the second part is based on an iteration procedure. In each iteration, meshes are first redistributed by a variational principle and then the underlying numerical solutions are updated by a conservative‐interpolation formula on the resulting new mesh. Several test problems in one‐ and two‐dimensions with a general geometry are computed using the proposed moving mesh algorithm. The computations demonstrate that the algorithm is efficient for solving problems with bore waves and their interactions. The solutions with higher resolution can be obtained by using a KFVS scheme for the SWEs with a much smaller number of grid points than the uniform mesh approach, although we do not treat technically the bed slope source terms in order to balance the source terms and flux gradients. Copyright © 2004 John Wiley & Sons, Ltd.     

非结构四边形二次Lagrangian有限元方程的代数多重网格法及收敛性分析

1 引言代数多重网格(AMG)法是求解有结构、非结构冈格下的PDEs离散化系统,以及其它大型稀疏矩阵方程的最为有效的方法之一,是当前多重网格法研究领域的热点．它主要侧重于粗化技术的研究,目前这方面已有大量的工作(见文[1～4]),其中基于部分几何信息和分析信息的AMG法,是当前AMG法发展的一个新趋势(见文[5～7])．