查询词典 finite difference approximation

Suppose G is a finite group, then QG is a semisimple Q-algera, obviously ZG is a Z-order of QG,we denote the maximal Z-order by ?.If G is not abelian, it is not an easy thing to determine г; if G is an abelian group, then QG is isomorphic to the direct sum of a finite number of number fields, and r is the direct sum of these rings of algebraic integers of those number fields, but which elements of QG belong to r is not clear.

设G是一个有限群，那么QG是一个半单代数，ZG是QG的一个Z-序，设Γ是QG的一个极大Z-序，当G是一个非交换群时，Γ的求解是困难的问题；当G是一个交换群时，QG同构于有限多个数域的直和，Γ相应的就是各数域代数整数环的直和，但Γ具体是QG中那些元素不清楚。

Several special finite element techniques, such as the chip separation criteria, friction model, heat conduction and adiabatic shear during cutting process have been implemented to improve the accuracy and efficiency of the finite element simulation.

利用该有限元模型分析了钛合金铣削加工中切削力和切削温度的周期变化规律，建立了切削力和切削温度曲线。

It obtains that the transport operator A has no complex eigenvalue s, and the spectrum of the transport operator A consists of finite real isolated eigenvalues which have a finite algebraic multiplicity in trip Pas.

本文研究了板几何中一类具各向异性、单能、均匀介质迁移算子A的谱，得出了该算子A在带域Pas中无复本征值和由有限个具有限代数重数的实离散本征值组成等结果。

It obtains that the transport operator A has no complex eigenvalue s,and the spectrum of the transport operator A consists of finite real isolated eigenvalues which have a finite algebraic multiplicity in trip Pas.

本文研究了板几何中一类具各向异性、连续能量、均匀介质的迁移算子的谱，得出了该算子A在带域Pas中无复本征值和由有限个具有限代数重数的实离散本征值组成等结果。

From the famous Gabriel's theorem ,a basic connected finite dimensional associative algebra A over an algebraically closed field can be looked as a quotient of a path algebra decided by a connected finite quiver Q.

由Gabriel 定理，代数闭域上基的，连通的有限维结合代数A 同构于一个由连通有限箭图Q 确定的路代数的商代数。

Shadow effect can not be neglected for thermal analysis of spacecraft,Accroding to the angle between solar light and antenna orbit plane and its orbit location,analytical geometry method was used for accurately calculating solar radiation heat flux distribution of reflector surfaces.To analyze the temperature field under heat flux,the formulations of net radiation flux density between two gray elements and the net flux density of gray surface under external thermal flux were deduced.Based on the characteristic of space environment,the nonlinear temperature distribution in transverse direction of reflector shell self radiation were considered,the finite element formulations were given for orthogonal material layered shell by Galerkin method.A layered element including a inner heat source layer was proposed,and the finite element formulation expressed by DOF of the inner heat source layer were put forward with temperature and heat flux boundarys between adjacent layer.

单馈反射面赋形天线是未来星载天线发展的一个重要形式，分析了基于物理光学、几何光学和几何绕射理论的理想反射面辐射场；介绍了基于几何光学的反射面天线赋形方法；针对赋形过程中辐射场的快速分析要求，比较分析了基于物理光学的Fourier-Bessel和Jacobi-Bessel级数展开方法以及GB展开分析方法；利用GB展开快速分析方法在20GHz频率下对0.6m口径的天线进行赋形分析，实现中国大陆的30dB增益覆盖，通过数值计算研究了固定增益期望下的口径尺寸随频率的变化，以及频率为20GHz的不同尺寸天线赋形后的覆盖目标区域最大增益的变化情况。

This technique is an improved and generalized version of the finite array Green's function method[1], and fit for analyzing all kinds of arrays including finite periodic and aperiodic arrays.

该法不受阵列单元排布形式、单元电流分布情况和单元数量的限制，对有限周期和非周期阵列的分析都有着较高的计算效率和稳定的收敛性。

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。

We were cousins—his grandfather was King of Scots,and his great-grandfather was Henry VII of England.

我们是堂姐弟——他的祖父曾是苏格兰国王，他的曾祖父是英格兰的亨利二世。

I do want to help you, but I am in a quandary now!

我是想帮你，但是我现在左右为难啊！