查询词典 discretization error

This section presents two kinds of characteristic schemes, one is the natural use of the usual backward Euler characteristic difference scheme ( [60] ) onto the triangular mesh, the other replaces the backward Euler's method by modified Euler formula to approximate the characteristic differential equation, so that the discretization for characteristic curve can get up to second order accuracy.

本节给出了两种三角形网格上的特征差分格式，第一种是通常的向后Euler型特征差分格式（[60]）在三角形网格上的自然运用，第二种采用§3.3、§3.4的离散思想，使用改进的Euler公式代替向后Euler公式来近似特征微分方程，使其对特征线的离散达到了二阶精度。

The approximate method of discretization may be used to calculate the persistent spin current in mesoscopic ring.

用离散化的近似方法也可以计算介观环中的持续自旋流。

Chapter 9: We report a large quantity of numerical experiments of 13 different algebraic multigrid algorithms for solving the Poisson equation, anisotropic equation, equation with cross-derivative terms, general matrix problems with large off-diagonal positive entries, biharmonic equation, Toeplity matrix, elasticity systems, finite element discretization of the Laplacian and even 3D problems. Particular attention is focused on asymptotic convergence factors and CPU-time consumed. Numerical results for many different types of practical problems demonstrate the efficiency and robustness of the proposed algebraic multigrid methods.

第九章：在各种代数多重网格算法的基础上，进行了大量的数值试验，具体给出了十三种不同的代数多重网格方法求解泊松方程，各向异性方程，带混合导数项的方程，带有大的非对角正元素的一般矩阵问题，重调和方程，托普利兹矩阵，弹性力学方程组，拉普拉斯算子的有限元离散，甚至三维问题的较为丰富的数值结果，重点关注它们的渐近收敛因子和所需的CPU时间，来源于不同类型问题的计算结果既为代数多重网格理论分析和算法的改进提供了很实用的资料，同时也证实了本文给出的代数多重网格算法的效绩和稳健性。

In the process of discretization of the auxiliary function, the traditional central difference formula is replaced by the backward difference formula, and numerical results show the method is of good stability.

在辅助函数的离散过程中用后向差分公式代替传统的中心差分公式，数值结果显示出良好的稳定性。

In Section 3, the BEM and the corresponding constant-element discretization is presented.

在第3条中，边界元法和相应的常数元离散。

Major research work and conclusions are summarized as follows:1 The development of molecular distillation are reviewed in respect of the principle, model research and application; The technical and structure parameters are analyzed with respect to the evaporation rate and separation factor.2 Based on analysis of heat transfer and mass transfer process in WFMD, the discretization forms of bow wave ordinary differential equations and film partial differential equations are obtained with Runge-Kutta method and finite difference method respectively.

主要工作与研究结果如下： 1 综述分子蒸馏技术的应用及其发展现状，从分子蒸馏技术的原理、模型研究及其应用的发展等进行了系统评述；并结合蒸发速率和分离效率这两个评价分子蒸馏效果的重要指标，对刮膜分子蒸馏器工艺参数与结构参数进行了分析与讨论。

It is shown that in Jameson's algorithm is not an orthogonal stream-lines coordinate system, but a local stream-lines coordinate system instead. Nevetheless, because of the finite-difference discretization in Jameson's scheme is not carried out along the direction of s and n, but along the Cartesian coordinates, the analysis on all terms of the full potential equation in Cartesian coordinates reveals that his scheme does take a back-ward difference along the streamwise exactly at all points in the supersonic flow region.

表明其所采用的坐标系不是真正的正交流线坐标系，而是局部流线坐标系；同时由于Jameson方法并不对s，n进行差分离散，而是在原笛卡尔坐标系下作差分离散，对笛卡尔坐标系下的全位势方程中的各项的分析表明，Jameson方法恰好能做到在超音速点沿真正的流线方向作后差分。

Withthe discretization of a few elements,CEM can lead to a high accuracy.

使用同样数目的自由度，复合单元法的精度远远高于常规有限元。

Spectral element methods for partial differencial equation is introduced in this study from viewpoint of the collocation approximation of Chebyshev polynomial. Wave Equation and its space discretization are deduced. Two time integral methods, central difference method and implicit Newmark method, are introduced, and their stability and applicability are also discussed in some details. The significance of absorbing boundary conditions in spectral element methods for Aeroacoustics is explained, and Clayton-Engquist-Majda absorbing boundary conditions is emphasized and introduced, then the discrete scheme of this boundary conditions is deduced and applied to spectral element methods for wave equation.

本文从Chebyshev多项式逼近理论出发，详细介绍了谱元方法求解偏微分方程的过程；推导了流体中的声波动方程并在空间上对其进行了谱元离散；详细讨论了两种时间积分方法──中心差分法和Newmark方法，分析了它们的稳定性条件，并从理论上对比了两种方法的优缺点和适用范围；将吸收边界条件推广应用于谱元方法求解气动声学问题中，重点介绍了Clayton-Engquist-Majda吸收边界条件的原理和公式，推导了该吸收边界条件的变分形式，并将其引入波动方程的离散形式中。

Two methods of discretization, collocation method and Galerkin method, have been dominant in existing meshless methods.

在最小二乘法和移动最小二乘近似的基础上提出了加权最小二乘无网格法。

The two-acre Dunbar Community Garden in Little Rock has served as a model for several years.

几年来，坐落于小石城，占地两英亩的邓巴社区菜园树立了一个标杆。

Jerry points to the jacket hanging in the bathroom. It's ruined, and unwearable What?

杰瑞指着洗手间里挂着的夹克，毁了，不能穿了）什么？