北京大学湍流与复杂系统国家重点实验室-学术成果

研究成果

陈璞

学术论文：

1.Yuan A New Quasi-Unsymmetric Sparse Linear Systems Solver for Meshless Local Petrov-GalerkinMethod (MLPG)

摘要：In this paper we propose a direct solution method for the quasi-unsymmetric sparse matrix(QUSM)arising in the Meshless Local Petrov-Galerkin method(MLPG).QUSM,which is conventionally treated as a general unsym metric matrix,is unsymmetric inits numerical values,but nearly symmetric inits nonzero distribution of upper and lower triangular portions...

2.两种高层建筑施工模拟快速计算方案

摘要：施工模拟方法能在结构分析中合理反映建筑结构逐层施工、逐层施加荷载的性质.经过对结构建造过程的分析研究,利用施工过程中的物理特征,在有限元变列高解法的基础上,通过改进传统的活动列解法和预处理共轭梯度(PCG)法,提出并实现了两种施工模拟快速计算方案.研究表明,与现有的许多计算方案相比,它们大大提高了计算效率,能够较好地满足实际工程分析的要求...

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学术报告：

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陈永强

学术论文：

1. Numerical modelling of fracture of particulate composites using SPH method.

摘要：Simplicity of mesh generation and robustness against mesh entanglement during large deformations are key attractive features of particle based methods. These features can be exploited in number of engineering problems where traditional techniques suffer due to aforementioned limitations. Numerical modelling of particulate composites is one of such ideal engineering applications where particle based methods can be effectively used due to their simplicity and robustness...

2. Small Polyhedron Reconnection for Mesh Improvement and its implementation based on advancing front technique.

摘要：Local transformation, or topological reconnection, is one of the effective procedures for mesh improvement method, especially for three-dimensional tetrahedral mesh. The most frequently used local transformations for tetrahedral mesh are so-called elementary flips, such as 2-3 flip, 3-2 flip, 2-2 flip, and 4-4 flip. Owing to the reason that these basic transformations simply make a selection from several possible configurations within a relatively small region, the improvement of mesh quality is confined. In order to further improve the quality of mesh, the authors recently suggested a new local transformation operation...

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学术报告：

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孙树立

学术论文：

1. A new high performance sparse static solver in finite element analysis with loop -unrolling. Acta Mechanica Solida Sinica, Vol. 18, No. 3, 2005

摘要：In the previous papers, a high performance sparse static solver with two-level unrolling based on a cell-sparse storage scheme was reported. Although the solver reaches quite a high efficiency for a big percentage of finite element analysis benchmark tests, the MFLOPS (million floating operations per second) of LDLT factorization of benchmark tests vary on a Dell Pentium Ⅳ 850 MHz machine from 100 to 456 depending on the average size of the super-equations, i.e...

2. High performance sparse static solver in finite element analysis with loop-unrolling. Advances in Engineering Software 34(4), 2003

摘要：Symmetric positive deﬁnite equation solvers play a very important role in promoting the efﬁciency of the ﬁnite element analyses(FEA).The focus of this paper is to describe a new storage scheme—cell-sparse storage scheme—and the corresponding algorithm of the direct symmetric positive deﬁnite equation solver in FEA. Loop-unrolling(or simply unrolling)techniques are incorporated into sparse solvers to enhance the vector speed...

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李水乡

学术论文

1，李水乡, 赵健, 陆鹏, 谢玉. 基本三维几何体的最高填充率. 科学通报, 2009, 54(6): 729-733

摘要：数值模拟结果表明, 基本三维几何体随机填充的填充率上限从高到底依次为: 立方体(0.78)、椭球(0.74)、圆柱(0.72)、球柱体(spherocylinder, 0.69)、四面体(0.68)、圆锥(0.67)、球体(0.64), 而规则填充的填充率上限依次为: 立方体(1.0)、圆柱和球柱体(0.9069)、圆锥(0.7854)、椭球(0.7707)、球体(0.7405)、正四面体(0.7175), 这两种填充率排序的顺序并不相同. 椭球、圆柱、球柱体、四面体和圆锥的随机填充率均与其形状有关...

2，李水乡, 赵健. 非球体填充的组合球模型及松弛算法. 计算物理, 2009, 26(3): 454-460

摘要：现有的松弛算法由于仅用于球填充而只考虑颗粒的平动,故提出考虑非球体转动的改进松弛算法并采用组合球模型,使其能够模拟任意形状非球体的随机填充以及多种非球体的混合填充.用多个球体的外包络面近似一个非球体外形的组合球模型,将非球体之间的接触转化为球体之间的接触,从而简化并统一非球体接触判断算法...

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