数值函数

3Numerical tests shows that indicator function method is a simple and fast method, by which better reconstruction can be gained for no superior knowledge of the physical properties about media.

数值实验表明，指示函数方法简单快速而准确，能在不对介质的物理性质有先验的假设基础上，给出较好的重构效果。

Two numerical methods using the integral function to do!

采用了两种数值方法做的积分函数！

The numerical results demonstrate that the MEI coefficients obtained using the technique,which takes dipole layer excitation as the "Metron" and the Green function in free space as the integral Kernel,are of higher precision over other techniques.

数值结果表明，利用电偶极子层激励作为测试子和自由空间格林函数作为积分核确定MEI系数的方法，比之其它方法具有更高的精度和明显的优点。

The research achievement are acquired as follows: 1From mathematical models for inverse scattering in two dimensional homogenous media including Dirichlet, Neumann, Robin,all kinds of probable mixed boundaries and cracks, direct and inverse scattering are discussed, and ill-posed integral equation and indicator function method are formulated for the diverse of boundary identification. It is shown that the kernel of the integral equation characters the boundary of scatterer, which is determined by solving it by virtual of regularity method, meanwhile, some numerical tests are given.

本研究取得了如下研究成果： 1）在二维均匀介质逆散射各种边界识别的数学模型（包括Dirichlet，Neumann，Robin，各种可能的混合边界问题，裂纹问题）下，分别考虑了正散射问题和逆散射问题，推导了上述各种边界识别的不适定积分方程以及指示函数方法，由于积分方程的核充分表征了散射物的边界，由此说明只要利用正则化方法求解该积分方程，就可以确定散射物的边界，并给出了一些数值实验。

Because the workpiece is in dynamic balance, the resultant moment acting on it should be zero. Introducing the moment from lapping tool and press head a moving differential equation is built. In this equation only workpiece rotating speed is unknown. It means that workpiece rotating speed can be got by this equation. Since there is a transcendental function in integral function of the equation an analytic result can not be got, only digital result can be got by a computer. Thus a change rule of workpiece rotating speed with lapping parameters is known, e.g. the radius of press disc ball socket, radius of press head ball, the distance between the workpiece rotating axis and lapping tool rotating axis, workpiece radius, modulus of elasticity of the press head and press disc, friction coefficients between the lapping tool and workpiece, and between the head and disc, pressure between the lapping tool and workpiece and pressure between the press head and press disc.

因工件处于动态平衡状态，其上所受到的来自于磨具和压头的力矩应相等，将二力矩表达式联立，建立工件运动微分方程，该方程中只有工件的旋转角速度是未知量，因此可以求出工件旋转角速度，但该方程积分式中含有超越函数，得不出解析解，只能通过计算机求出数值解，得出工件旋转角速度随各研磨参数的变化规律，如压盖球座半径、压头的球头半径、工件回转中心相对磨具回转中心的偏心距、工件半径、压头和压盖材料的弹性模量、磨具与工件间的摩擦系数、压头压盖间的摩擦系数、磨具与工件间的压强、压头压盖间的压力等。

In this paper,the singularity in the integrand of electrical field integral equation for 3-dimensional vector fields scattering is first analyzed.

本文研究了电场积分方程中被积函数奇异性的处理方法，特别是三维矢量散射分析中出现的高阶奇异性，给出了两种解决积分方程奇异性的数值方法。

The vector surface integral equation can't be applied to numerical computation directly because its integrands possess the high order singularity.

矢量的面积分方程因其被积函数具有高阶奇异性，不能直接应用於数值计算。

Dept.of Microwave Eng.,UEST of China,Chengdu 610054,ChinaAbstract:In this paper,the singularity in the integrand of electrical field integral equation for 3-dimensional vector fields scattering is first analyzed.

本文研究了电场积分方程中被积函数奇异性的处理方法，特别是三维矢量散射分析中出现的高阶奇异性，给出了两种解决积分方程奇异性的数值方法。

In the method,thematrix exponential is calculated precisely by using 2N algorithm and the integration offunctional matrix by parts is applied.

首先依据常微分方程的经典理论，运用指数矩阵的2N类精细算法及函数矩阵的分部积分法建立数值求解常微分方程的一般方法。

Analysis and simulation results show that tail distribution is very different from Gaussian; the effects of passive intermodulation interference on communication systems are mainly in the region of low bit error rates.

分析和数值结果表明：互调产物的幅度一般来说随阶数的增加而下降；高阶互调产物的下降行为本质上与传递函数的类型有关。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。