查询词典 calculus of finite differences

The basic idea is to set a continuous solution of the region with a finite number of discrete points instead of a grid consisting of, these discrete points called grid nodes the solution of a continuous area on a given function of continuous variables used in the definition of discrete grid variable function approximation the original equation and boundary conditions in the micro-business operators to approximate differential, integral with the points and to approximate, so the original differential equations and boundary conditions are replaced by algebraic equations near Side, that is, finite difference equations , solve this equation group can get the original problem in discrete points on the approximate solution.

基本思想是把连续的定解区域用有限个离散点构成的网格来代替，这些离散点称作网格的节点；把连续定解区域上的连续变量的函数用在网格上定义的离散变量函数来近似；把原方程和定解条件中的微商用差商来近似，积分用积分和来近似，于是原微分方程和定解条件就近似地代之以代数方程组，即有限差分方程组，解此方程组就可以得到原问题在离散点上的近似解。

In this paper we introduce a finite element program design method for solving 3 D thoracic electrical field distribution,based on Borland C++ for DOS and using isoparametric element of arbitrary hexahedron.In the process of solving final finite element equation,this paper uses the method of blocking and 'getting big number' to deal with total coefficient matrix and boundary conditions.

本文介绍了一种采用等参数8节点任意六面体单元来求解人体胸腔三维恒定电场分布的有限元程序设计方法，程序的编制基于BorlandC＋＋ForDOS的编程环境，在对最终形成的有限元代数方程的求解过程中采用了分块处理总系数矩阵及"取大数"处理边界条件的方法。

Finite Element Method is an important means of engineering subject and has been proved to be a common method in many subjects. However, disadvantages still remained. During the structural analysis, large amount of high-order units were used in order to ensure the precision of arithmetic solution when using Finite Element Method to do discrete processing. This will cause high order of coefficient matrix of corresponding equation group.

有限元方法是工程学科的重要工具，被证明为在许多科学和工程领域中连续物理系统模拟的一种普遍方法，但缺点是随着工程结构分析问题越来越复杂，在结构分析中，为保证数值解的精度，在使用有限元方法离散处理时，往往要用大量的高阶单元将结构剖分得很密，这时相应的代数方程组的系数矩阵的阶数很高，即使用目前速度最快的串行机来进行求解，费时仍然太多且问题的规模受到内存容量的限制。

Firstly, we establish a topological space associated to the derived category of a finite dimensional algebra with finite global dimension, which is a generalization of module variety and complex variety.

首先，我们在有限整体维数的代数的复形范畴上建立了复形拓扑空间。

In order to obtain the variation law of temperature during casting solidification to improve casting quality,a finite element method combining with a finite difference method was used to discretize time and space variables in the governing equations of astable heat-conduction in the process of casting solidification so as to obtain the algebraic equations for casting and mold temperature.

为了掌握铸件凝固过程中温度场的变化规律以提高铸件质量，采用有限元和有限差分相结合的方法离散铸件凝固过程非稳态热传导方程的空间和时间变量，得到了关于金属铸件和铸型温度的代数方程。

The results of numerical modeling indicate that the thin film microstrip lines with finite ground width have good broad band characteristics and the characteristic impedance, attenuation constant and effective dielectric constant have small change with the finite ground width changing.

作者用该程序对有限接地面薄膜微带线进行了时域仿真，结果显示在保证传输模不受干扰的情况下，在较宽频带范围内有限接地面对微带特性有微弱影响。

This paper is concerned with the classification of fuzzy finite automata and the minimization algorithm of fuzzy finite automata.

本文研究了模糊有限自动机的分类和模糊有限自动机的状态最小化算法。

Without the Axiom of Choice, however, one cannot prove that every D-finite set is finite.

你可以找一个看得懂英语的人，让他告诉你，我有没有骗你，有没有正面回答。

For program (2), we can classify finite dimensional basic Hopf algebras of finite representation type completely now.

对于(2)，目前，我们已经给出了有限型的完整分类。

Simulations based on finite integration method are carried out in a wide frequency range for a balanced feeding finite wide-angle biconical antenna and many results including input impedance and far fields are obtained.

利用基于有限积分法的电磁场仿真技术对平衡馈电的有限长宽角双锥天线作了计算，得到了天线在很宽频带内输入阻抗、远区辐射场与频率的关系曲线。

You can snipe the second and third union leaders from this position.

您可以鹬第二和第三工会领袖从这一立场出发。

Aiming at the currently shortage of XML streams quality detecting, this paper proposes a new forecasting method of XML streams quality by least squares support vector machines, which is used the method of XML keys' vector matrix as windows, and vector product wavelet transform to multilevel decompose and refactor the XML streams series, that can fulfill real-time checking demand of XML quality, and ensure constraint, consist- ency and integrality. For even more adapting net load, it proposes a control strategy by weight and adaptive adjustment to ensure XML streams quality.

针对当前XML数据流质量检测存在的不足，提出构建XML键的矢量矩阵作为窗口，利用矢量积小波变换多级分解与重构XML数据流，再结合最小二乘支持向量机对XML数据流质量进行预测的一种方法，满足XML数据流质量重构时实时检测的要求，保证XML数据的约束性、一致性与完整性；为了更好的适应网络负载，采取加权与自适应窗口调整等调度策略充分保证XML数据流的质量检测。