查询词典 finite difference approximation

Maxwell's equations are replaced by a set of finite difference equation. If we solve it in time domain, we can get Finite Difference Time domain method.

从麦克斯韦方程出发建立地质雷达的数学模型，麦克斯韦方程可以转化成有限差分方程组，若在时域中对其求解就是时域有限差分方法。

The main contents of this course include: the construction, convergence, compatibility and stability of finite difference scheme of elliptic equation, parabolic equation and hyperbolic equation, the construction method and computation format of finite difference scheme of a system of partial differential equations.

本课程主要内容有：椭圆型方程的有限差分格式的构造，有限差分格式的收敛性，相容性及稳定性、抛物型方程的有限差分格式的构造，有限差分格式的收敛性，相容性及稳定性、双曲型方程的有限差分格式的构造，有限差分格式的收敛性，相容性及稳定性、偏微分方程组的有限差分格式的构造方法及有关的计算格式。

It tries its best to avoid using the finite difference grid, so that it can eliminate the artificial dispersion which arises from the injudiciously finite difference grid.

第四章提出了一种交替方向区域对分的FCM，用于模拟二维多孔介质中的生物降解过程，它试图尽可能的避开使用有限差分网格，从而消除由于网格选取的不合适而导致的人工弥散现象。

How to calculate the synthesis operator is the key problem of controlled illumination prestack depth migration. In this paper the inverse time focusing operator is synthesized based on the traveltime calculation method of finite difference approach, and with this synthesis operator the authors calculate the focusing point controlled illumination prestack depth migration using Fourier finite difference. The test results of Marmousi model show its effectiveness and the great advantage of improving computational efficiency.

进行控制照明叠前深度偏移的关键是合成算子的选择，笔者基于有限差分的走时计算方法合成了逆时聚焦算子，基于该合成算子利用傅里叶有限差分法进行了聚焦点控制照明叠前深度偏移，针对Marmousi模型的试算结果表明了该方法的有效性及其在提高计算效率方面的巨大优势。

In this paper,the variable space finite difference method of lines is presented on the basis of equal space finite difference method of lines.

在等步长有限差分线法的理论基础上，构造出变步长的有限差分线法格式，并对其进行了误差分析。

Author, secondly, starts from the approximate expandness of square root operator, perform mathematical calculations for finite difference operator in frequency-space domain, Fourier finite difference operator in mixing domain(frequency-space and frequency-wavenumber domain) and general screen operator in mixing domain, compare and discuss their precision of their wavefield, adaptability for lateral velocity variations, computation efficiency and stability.

第二，从平方根算子的近似展开出发对频率—空间域的有限差分算子、混合域(频率—空间域；频率—波数域)的Fourier有限差分算子、混合域的广义屏算子进行了推导并对其波场描述精度、对横向变速的适应性、计算效率和稳定性进行了比较与评述。

In the numerical computation, a two-dimensional numerical method integrating finite element method and difference method was employed, where the finite element method is used to calculate the magnetic field of the permanent magnetic guideway and the difference method is used to calculate the induced current in the superconductor, then the levitation force and the lateral force were calculated by Lorentz formula.

在数值计算部分，实现了一种集有限元法与差分法为一体的数值计算方法。

But the finite difference methods require that the computational domain is regular, and usually people construct the finite difference scheme for one dimension and then extend it to two or three dimensions in a dimension by dimension fashion.

有限差分方法要求计算区域比较规则，随着工程问题的复杂化，计算区域也变得复杂，这对数值方法提出了新的挑战。

In this paper, the maximum likelihood algorithm with process and measurement noise for nonlinear continuous-discrete system given by Jategaonkar and Plaetschke is improved in two aspects: 1 to avoid the disadvantages of sensitivities computation by common finite-difference method, in which the perturbation sizes should be selected optionally, an improved finite-difference method with best perturbations, is presented. 2 to improve the numerical stability of Jategaonkar's algorithm, maximum likelihood algorithm with fast triangular square-root decomposition filter is given.

摘要对Jategaonkar等人给出的同时计及过程及观测噪声的非线性连续-离散系统的极大似然算法从两个方面进行了改进：1给出了计算灵敏度的最佳摄动有限差分算法，避免了普通有限差分法计算灵敏度矩阵时需人为选择参数摄动量大小而带来的缺点；2给出了具有快速三角化平方根滤波的极大似然算法，提高了原算法的数值稳定性。

In order to analyze vertical bearing behavior of large diameter belled pile in soft substratum, three-dimensional non-linear finite-difference numeric models are established with finite-difference program, calculated and measured results are contrasted, and it proves that the calculation models and the chosen parameters are rational.

为分析存在软弱下卧层的大直径扩底桩的竖向承载性状，本文利用有限差分程序建立三维非线性有限差分数值模型，将计算结果与实测数据进行对比，验证了计算模型与参数选取的合理性。

The studies on the developing of new media are very important to the increasing of the area density of HDD and to the implementation of hybrid recoding technology.

光磁混合记录方法，是一种可以突破超顺磁极限的限制，并进一步提高硬盘记录密度和读写速率的一种新型超高密度信息存储方式。

In io, mTOR inhibition promotes T cell anergy under conditions that would normally induce priming.

体内研究中，在正常可激发免疫反应的条件下，抑制mTOR可促使T细胞无能。