查询词典 numerical system

The angular distribution of the bistaticscattering coefficient of HH polarization were obtained by numerical implementation. Influences of the permittivity and the mean layer thickness of intermediate medium, friction velocity and the frequency of the incident wave on the bistatic scattering coefficient were discussed. The basic characteristics, the zonal characteristics and the characteristics with varying of frequency of the scattering coefficient from stratified sea surface were obtained. The numerical results show that the scattering coefficient has approximate "quantization" characteristics.

通过数值计算得到了HH 极化双站散射系数随散射角的变化曲线，讨论了中间介质介电常数和厚度、摩擦风速和入射波频率对双站散射系数的影响，得到改进的一维分形分层海面散射系数的基本特征、分区特征和随频率变化的特征，结果表明散射系数近似具有"量子化"特征。

In this dissertation, the following critical theoretical problems on local La-grangian numerical differentiation are studied: explicit formulas, local estimate for the remainder, and the highest order of approximation in the case that the values of the function at these interpolation nodes have perturbationsLagrangian numerical differentiation is a method that the Lagrange interpolation polynomialis differentiated to approximate the derivative, where Tn ={t_0,t_1,......

本文主要研究有关局部Lagrange数值微分法的一些关键性的理论问题：公式的显式表示，余项的渐近估计，以及在插值数据有扰动的情况下，局部Lagrange数值微分法的最大逼近阶。

Firstly, the isotropic difference templates were introduced to approximate the differential in the ADI-FDTD method, and the weighting coefficients of difference terms were determined for implementing isotropic numerical dispersion; Then the permittivity and permeability were adjusted manually to reduce the numerical dispersion error in any directions. Therefore the simulation accuracy and efficiency can be improved effectively for time domain problems with some finite bandwidths.

该方法在ADI-FDTD方法的差分近似微分中引入各向同性差分模板，并通过确定各向同性差分的加权系数来近似实现各向同性，然后人为修正空间的介质参数来减少各个方向上的数值色散误差，因此在模拟一定带宽的时域问题时可有效提高计算精度和计算效率。

Some numerical examples are given to show that the numerical method presented is an approximation method with high efficiency and convergence.

数值计算表明本文数值方法是一种高效和收敛的近似方法。

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。

The results of numerical simulation reveal that the resistance to liquefaction of sands increases as the angularity of particles increased, and the micro_mechanism is related to the average coordination number of sample. It also found that the numerical sand sample made from randomly mixing multiple shapes of sand can quantitatively reflect the regularity of fabric evolution of sands during liquefaction.

结果表明，颗粒棱角度越大，试样抗液化能力越强，其在细观机理上与初始平均接触数大小有关；随机混合仿真试样可以从定性角度反映实际砂土振动液化过程中的细观组构演化规律，为今后进一步的定量研究奠定了基础。

In this paper the numerical solution of Green's function of potential in 2-D arbitrary inhomogeneous media with axial symmetry has been given by using the numerical mode matching theory.

利用数值模式匹配理论，对具有轴对称的任意二维非均匀介质中位场的格林函数给出数值解。

By analyzing the reason of the numerical oscillation phenomenon and computing the temperature field in plate rolling process,it is found that numerical oscillation can be restrained effectively when the heat capacity matrix is lumped by using backward difference scheme.

近年来，许多研究人员采用有限元法分析热轧和淬火等过程中的瞬态温度场。

The control volume integration was applied to deduce the discrete expressions of the convection-diffusion equations. The staggered grid and SIMPLE algorithm were introduced to deal with coupling between pressure and velocity, and then the numerical computation expressions of such variables as fluid flow velocity and pressure were deduced. Using the backward difference method and incremental theory to discretize the governing equations for fields of chemical reaction, material structure and chemorheology, the numerical computation expressions of variables such as the monomer conversion, average molecular weight and fluid viscosity were constructed.

应用控制容积积分法导出了对流—扩散方程的离散表达式，引入交错网格技术与SIMPLE算法，实现了耦合的压力场与速度场的分离式求解，推导得到了流体的流动速度、压力等物理量的数值计算式；采用向后差分方法和增量方法，实现了化学反应场、材料结构场、化学流变场控制方程的离散，获得了反应转化率、聚合物平均相对分子质量、流体黏度等物理量的数值计算式。

Whereas analytical method and the before-mentioned numerical method have some places to improve and the determination characteristics of satellite of middle-low orbit, this paper presents a new numerical project of determination of obvious characteristics on condition that range of determination is not very long and the precision of determiantion is the meter grade, and is realized by a software.

鉴于分析法定轨和上述通常采用的数值法定轨都有各自可改进之处，本文针对一般中低轨卫星定轨的特点，在弧段不太长和定轨精度为米级的情况下，给出一种具有明显特点的数值定轨方案，且以软件具体实现了这种方案，并经受了实测资料的考验。

In the days of sailing vessels the crew were afraid they would be becalmed on the ocean.

在使用帆船的时代，船员们担心他们会因为无风而无法在海洋上航行。

As long as foreign donors pay the PA's salary bill, few expect a new intifada.

只要外国继续为巴权力机构的薪水买单，希望发动新暴动的人便寥寥无几。