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151.
给出计算轴对称高速碰撞问题的拉格朗日无结构三角形网格有限体积法的并行格式,并给出以小巨型机AliantFX/40为目标计算机的算例数值模拟结果和效率分析 相似文献
152.
用有限元自适网格控制结构应力分析的精度 总被引:1,自引:0,他引:1
本文涉及有限元结构应务分析精度控制的三个基本方面:1)自适应的有限元网格自动生成技术;2)有限元应力分析的误差估计:3)用单元尺寸场将误差分布用于形成新网格。 相似文献
153.
The structural and magnetic properties of Ta-doped Ca4Mn3−xTaxO10 (0≤x≤0.3) compounds have been investigated. Structural refinement indicates that the Ta doping maintains the orthorhombic layered perovskite structure with space group Pbca as Ca4Mn3O10 but induces an increase in both unit cell volume and octahedral distortion. The magnetization measurements reveal that the magnetization first increases and reaches to maximum for the x=0.1 sample and then gradually decreases with the increase of Ta content. There appear short-range ferromagnetic (FM) clusters in all the doped samples, which are caused by the double-exchange interaction between Mn4+ and Mn3+ that is induced by the charge compensation effect. As x is higher than 0.1, the overall results show evidence for the gradual appearance of a cluster glass behavior. When x increases to 0.3, the long-range antiferromagnetic (AFM) ground state is melted into the short-range magnetically ordered regions due to the increase of Ta5+ and Mn3+ at the expense of Mn4+. The competition between AFM regions and FM clusters makes the short-range magnetic components frustrate when the temperature falls to a frustrating point, and thus cluster glass transition occurs. 相似文献
154.
Abdullah S. Al-Dughaither Ahmed A. Ibrahim Waheed A. Al-Masry 《Journal of Saudi Chemical Society》2010,14(4):331-339
Effects of design parameters on performance of wire-mesh mist eliminators were experimentally investigated in 15 cm bubble column. The demisters performances were evaluated by droplet collection efficiency as a function of wide ranges of operating and design parameters. These parameters include: droplet size exiting the demister (250–380 μm), specific surface area (236–868 m2/m3), void fraction (97–98.3%), wire diameter (0.14–0.28 mm), packing density (130–240 kg/m3), and superficial gas velocity (0.109–0.118 m/s. All demisters were 15 cm in diameter with 10 cm pad thickness, made from 316L stainless steel layered type demister pad wires. Experiments were carried out using air–water system at ambient temperature and atmospheric pressure. The experimental data on the droplet removal efficiency were obtained using Malvern Laser Droplet Sizer. The removal efficiency was found to increase with the increasing the demister specific surface area, packing density, and superficial gas velocity. In contrast, the removal efficiency was found to increase with decreasing the demister void fraction and wire diameter. The separation efficiency is correlated empirically as a function of the design parameters. A good agreement was obtained between the measured values and the correlation predictions with ±5% accuracy. 相似文献
155.
Stephen D. Bond Jehanzeb Hameed Chaudhry Eric C. Cyr Luke N. Olson 《Journal of computational chemistry》2010,31(8):1625-1635
The Poisson‐Boltzmann equation is an important tool in modeling solvent in biomolecular systems. In this article, we focus on numerical approximations to the electrostatic potential expressed in the regularized linear Poisson‐Boltzmann equation. We expose the flux directly through a first‐order system form of the equation. Using this formulation, we propose a system that yields a tractable least‐squares finite element formulation and establish theory to support this approach. The least‐squares finite element approximation naturally provides an a posteriori error estimator and we present numerical evidence in support of the method. The computational results highlight optimality in the case of adaptive mesh refinement for a variety of molecular configurations. In particular, we show promising performance for the Born ion, Fasciculin 1, methanol, and a dipole, which highlights robustness of our approach. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
156.
157.
In this paper, we propose a nonlinear PDE model for reconstructing a regular surface from sampled data. At first, we show the existence and the uniqueness of a viscosity solution to this problem. Then we propose a numerical scheme for solving the nonlinear level set equation on unstructured triangulations adapted to the data sample. We show the consistency of this scheme. In addition, we show how to compute nodewise first and second order derivatives. Some application examples of curve or surface construction are provided to illustrate the potential and to demonstrate the accuracy of this method. 相似文献
158.
聚焦评价函数和极点搜索策略是自动聚焦的重要模块,直接影响聚焦的效果.为同时满足自动聚焦速度和精度上的要求,提出了一种新的自动聚焦算法.该算法综合了快速改进的灰度差分法和高精度小波变换法的优点,根据各阶段聚焦评价函数的梯度选择合适的评价函数和镜头移动步长,并且实现了从大步长快速粗扫到小步长精确细调的过渡.实验表明,与传统... 相似文献
159.
Yagawa G 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2011,87(4):135-151
The free mesh method (FMM) is a kind of the meshless methods intended for particle-like finite element analysis of problems that are difficult to handle using global mesh generation, or a node-based finite element method that employs a local mesh generation technique and a node-by-node algorithm. The aim of the present paper is to review some unique numerical solutions of fluid and solid mechanics by employing FMM as well as the Enriched Free Mesh Method (EFMM), which is a new version of FMM, including compressible flow and sounding mechanism in air-reed instruments as applications to fluid mechanics, and automatic remeshing for slow crack growth, dynamic behavior of solid as well as large-scale Eigen-frequency of engine block as applications to solid mechanics. 相似文献
160.