查询词典 initial approximation

In this article, the BINIDCT algorithm, a fast approximation of the Discrete Cosine Inverse Transform and its efficient VLSI architectures for hardware implementations with Wishbone bus are presented.

1引言离散余旋变换(Discrete Cosine Transform，DCT)和其反变换(Inverse Discrete Cosine Trans-form，IDCT)广泛地应用于图像和视频压缩、解压缩领域中，其中包括JPEG、MPEG1-2、H.26x、MPEG4等图像标准中。

Modifications to the conventional layer by layer optimization method make it possible to avoid computing Hessian Matrix and its inverse form, thus it can decrease computational complexity dramatically. Simulation results for some practical problems such as function approximation and XOR problem, have demonstrated improvements over classical back-propagation algorithm and conventional layer by layer optimization algorithm.

本文在传统逐层优化算法上的改进避免了反复计算 Hessian 矩阵及其逆矩阵，因而可以减少计算量，对一些应用问题，如函数逼近、异或等问题的仿真实验证实了新的算法比经典的 BP 算法以及现存的逐层优化算法的训练速度更快、可靠性更好。

Estimation of the attenuation law is based on the inverse transfer function of the object approximation in the frequency domain.

估算的衰减规律，是基于逆传递函数的对象近似的频域。

The main contents include: Some preliminary theory (introduction to Sobolev spaces and variational formulations for differential equations); finite element methods for one-dimensional elliptic problems; the construction methods for general finite elements; error estimates for interpolation operators and inverse inequalities for finite element spaces; a priori and a posteriori error estimates for the finite element method for high-dimensional elliptic problems; some typical spectral methods for partial differential equations; error analysis for the spectral approximation for some linear and nonlinear partial differential equations.

主要内容有：准备知识（Sobolev空间的基本概念和主要结果，微分方程的变分描述）；一维椭圆型方程有限元方法；一般有限元的构造；插值算子误差估计和逆不等式；高维椭圆型方程的先验、后验误差估计；求解偏微分方程的几类谱方法；线性与非线性问题谱逼近的误差分析等。

The harmonic field of electric dipole source on the uniform earth surface is converted into transient field by inverse Laplace transform,and the Bz/ t transient curve is calculated.The Hz transient curves on the stratified earth surface are obtained from cosine transform calculated by broken line approximation.

由逆拉普拉斯变换将均匀大地面上的电偶极子源谐变电磁场转换为瞬变电磁场，并计算出Bzt瞬态曲线；对分层大地面上的瞬变电磁场，采用折线逼近法计算余弦变换得出Hz瞬态曲线。

Methods Ionization chamber and film dosimetry methods were used to compare the angular dose distribution, point source approximation in the area close to the source,the coincidence of inverse square law of source strength and the scatter and attenuation in water medium,of a cylindrical, miniature 192 Ir source and "the ideal point source".

用电离室法与胶片法实测国产192Ir放射源空间剂量角分布、点源的近似性与源强反平方定律的符合性以及水介质散射与衰减特性，并与点源剂量分布特性比较。

The main contents include studying purpose, researching object, the introduction about this course; governing equations, boundary conditions for an inviscid irrotational flow, linearized approximation for small-amplitude waves; illuminations of wave factors and relevant physical variables; the propagating waves in deep and shallow water; discussion of physical meanings of group velocity.

包括学习目的、研究对象、主要内容简介；控制方程，描述无粘、无旋运动的边界条件，对边界条件的线性化近似；波要素和有关物理量的介绍；深水和浅水条件下的行波问题；讨论群速度的物理意义。

Using RBF neural network substitutes BP network as the approximation of implicit performance function, and the response surface is formed in the sphere of hyper-pyramid at iteration step.

采用径向基函数神经网络，代替目前常用的BP网络，迭代过程中在超锥体的范围内构造响应面，逼近隐式的非线性功能函数。

Established a series of results on the Jacobi approximation, and proposed the Jacobi spectral method for singular problems, which produces the possibility of using spectral mcthod for problems in a ball.

最近，郭本瑜教授等建立了一套相当完整的Jacobi正交逼近理论，并提出了适合于一类奇异问题的Jacobi谱方注。

Results show that radial basis function and point interpolation methods possess Kronecker Delta function property, but the robustness is poor in some cases; the MLS approximation function does not possess Kronecker Delta function property, but it has good robustness. Differences among the three discretization schemes of meshless method are as follows:the collocation method requires no numerical integration and very little computational time while its robustness is poor; Galerkin method is not a truly meshless method due to the background meshes required for integration; the Petrov-Galerkin method is a truly meshless method and need numerical integration in each sub-domain, so it needs more computational time.

分析结果显示：径向基函数和点插值法均具有d 函数属性，但计算稳定性差；移动最小二乘近似函数不具有d 函数属性，但计算比较稳定；无网格方法中的3种离散方法不同之处在于：配点法不需要积分，计算量小，计算稳定性差；Galerkin方法需要借助背景网格进行积分，它不是真正的无网格方法；Petrov-Galerkin方法，是一种真正的无网格方法，它需要对每个子域进行积分，计算工作量较大。

Pachomius manual labour was organized as an essential part of the monastic life; and since it is a principle of the monks as distinguished from the mendicants, that the body shall be self-supporting, external work of one sort or another has been an inevitable part of the life ever since.

根据圣pachomius体力劳动组织作为一个重要组成部分寺院生活；以来，这是一个原则的和尚，作为有别于乞丐，该机构应自支撑，对外工作的这种或那种已一个必然的一部分，生活至今。

In order to study the effects of parametrical rolling on the ship movement and tilts, in allusion to ship's navigating in regular following waves, the equation of ship rolling motion is transformed into normal Mathieu equation by proper variable replacement when strong parametrical excitation in restoring moment varied according to sine or cosine wave.

为研究参数横摇对船舶运动和倾覆的影响，通过对船在规则波上随浪航行时，恢复力矩中出现的1个以正余弦规律变化的强参数激励项进行适当的变量置换，将船舶的横摇运动方程转换成标准形式的Mathieu方程。