查询词典 best approximation

Several strong results on neural network approximation capability obtained in this dissertation are important in the approximation theory and applications of neural networks.

本文系统地研究了多层神经网络的非线性逼近能力，给出了多层网络可一致逼近有限维空间R〓紧集上的连续函数、无穷维函数空间紧集上的连续泛函和连续算子以及布尔函数的理论证明。

In theory of approximations, the classic methods of polynomial approximation for rational expression are various interpolations and operator approximations, such as Lagrange interpolation, Hermite interpolation and Bernstein polynomial approximation.

在逼近论中，用多项式逼近有理式的经典的方法是各种插值与算子逼近方法，如Lagrange插值、Hermite插值和Bernstein多项式逼近等。

A series of Gaussian digital approximation filters used in roundness measurement were designed on the basis of approximation method and bilinear transformation.

文中用逼近法和双线性变换法，设计了用于圆度测量的高斯数字逼近滤波器，并给出了零相移的递归滤波算法，计算量小，计算效率高，易于实现。

The primitive notion in rough set theory is a pair of upper and lower approximation operators induced by the basic structure, an approximation space, consisting of a universe of discourse and a binary relation on it.

粗糙集理论的核心算子是从近似空间导出的一对非数值型算子-上近似算子与下近似算子，这一对近似算子是整个粗糙集理论与应用的基础。

It is proved that the upper approximation of such fuzzy rough set in a fuzzy approximation space is just its image derived according to generalized extension principle and binary fuzzy similar relation.

通过对偶方式定义了模糊集的上、下近似算子，给出了模糊粗糙集在相应的模糊关系及模糊集的截集下的表示定理，证明了这种模糊粗糙集关于模糊近似空间的上近似恰为其在二元模糊相似关系下导出的广义扩张原理之下的像。

The general form of solution for the non symmetric matrix A is given, the expression of optimal approximation solution is presented, and an algorithm for solving the problem is described. The total least squares problem with symmetric and bisymmetry constraints is discussed respectively. A sufficient condition for existence of solution is derived by use of the theory of matrix Ricaati equation. The general form of solution is given if the problem has a solution, and the expression of optimal approximation solution is presented. Some numerical examples are given.

对矩阵A是非对称情形，给出了解的一般表达式，证明了最佳逼近问题解的存在唯一性，并给出了其解的表达式，描述了求解问题的算法；讨论了带对称和双对称约束的总体最小二乘问题，利用Ricaati矩阵方程的理论得到了解存在的一个充分条件，分别对对称矩阵和双对称矩阵两种情形，给出了解的一般表达式，证明了最佳逼近问题解的存在唯一性，给出了其解的表达式，提出了求解这些问题的算法，并给出了数值例子。

It solves the imaging problem in great contrast. In chapter 2, the author deeply studies and analyzes the arithmetic of the method of Born approximation inversion and points out the limitations and disadvantage of the method. The good inverse results can be obtained in little disturbance by Born approximation.

本文提出的反演理论，考虑到散射序列中高阶项对成像结果的影响，在反演时利用逆散射序列中的高阶项以弥补散射场数据的丢失，使得在大扰动量的情况下同样能够实现界面位置和形态的精确成像，解决了大对比度情况下的成像问题。

It enlarges the range of quasi-linear Born approximation, and makes the prestack depth migration method based on quasi-linear Born approximation to be able to adapt strong lateral velocity variation.

在散射波场计算中，使用了一个更稳定的散射波场计算公式，扩大了拟线性Born近似的应用范围，使基于拟线性Born近似的叠前深度偏移方法能够适应更强的横向速度变化。

The calculations have shown that the second Born approximation can give better results,as compared with experiments.The prediction of K-W formula is only equivalent to the first Born approximation.

结果表明第二玻恩近似结果与实验结果符合得比较好，K-W公式的预言只相当于第一玻恩近似。

A one-sided difference approximation is used for convection terms and a second-order central difference approximation for diffusion term.

二阶一边差分逼近用于对流项的离散，二阶中心差分逼近用于扩散项的离散。

In the days of sailing vessels the crew were afraid they would be becalmed on the ocean.

在使用帆船的时代，船员们担心他们会因为无风而无法在海洋上航行。

As long as foreign donors pay the PA's salary bill, few expect a new intifada.

只要外国继续为巴权力机构的薪水买单，希望发动新暴动的人便寥寥无几。