查询词典 calculus of finite difference

In order to solve the problem,starting from the analysis of the simplest plane wave numerical theory,we derived the formula of relative phase velocity and group velocity under the condition of arbitrary high-order finite-difference approximation,and gave the computational method for acquiring the optimum Courant number,and then analyzed the anisotropic effects due to finite difference approximation.

针对此，从最简单的平面波数值理论分析出发，推导了任意高阶有限差分近似条件下相对相速度和相对群速度的计算公式，给出了求解最佳Courant数的计算方法，分析了差分近似造成的各向异性效应。

A new scheme for approximating the solution of 2D Maxwell's equations-the high order symplectic scheme is proposed to overcome the shortcoming of the conventional finite difference time domain. The scheme is obtained by discretizing the Maxwell's equations in time domain based on symplectic scheme with high order, and then evaluating the equation in spatial domain with second or fourth order finite difference approximation.

为克服标准时域有限差分方法的缺陷，引入一种新的数值计算方法－高阶辛算法求解Maxwell方程，即在时间上用高阶辛差分格式离散，空间分别采用二阶及四阶精度的差分格式离散。

College of Guandong Business, Guanzhou 510320, China）Abstract: Since large-scale vertical quench furnace is voluminous, whose working condition is a typically complex process with distributed parameter, nonlinear, multi-inputs/multi-outputs, close coupled variables, etc, dynamically decoupling control algorithm of temperature distributed parameter system in the furnace was presented, by which the whole system was decoupled to several subsystems and the implementation of controller was simplified. With finite difference approximation, the space and time step size was solved to ensure the convergency of finite difference approximation. After decoupling, the subsystems were controlled with self-learning PID control algorithm. The results show that the temperature control precision and homogeneity are improved; the overshoot and process in temperature rising period are reduced simultaneity.

摘 要：针对大型立式淬火炉体积庞大，工况复杂，炉内温度分布呈本征非均匀性，具有多输入/多输出、非线性、强耦合等特性，难以实现炉内温度高精度高均匀性控制目标等问题，提出一种温度分布参数系统动态解耦控制算法，其原理是：采用有限维逼近方法将对象解耦为多个独立的子系统，简化控制器的实现过程；通过分析有限维逼近方法的收敛性，获得保证收敛性的空间和时间步长应满足的条件；解耦后的子系统采用自学习PID控制算法，实现炉内温度高精度和高均匀性控制以及升温过程的快速性和小超调。

There are many ways to analysis and computation of Mikthw's two rotations equation,finite difference method is the most one while using the finite difference method,a flood of data need be collected and computed.

而在目前高性能计算机系统中，最广泛使用的并行环境是MPI(Message Pass-ing Interface)，它已成为一种并行程序的标准。

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。

I go to school at night.

我是上上学。

Clear Tip Nasal Aspirator: A soft time and gentle suction action makes removing excess mucus easy.

鼻吸明确提示：一个柔软的时间和温柔吸力行动使消除过剩的粘液容易。