查询词典 approximation theory

By using slowly-varying envelope approximation, a family of solutions of the paraxial wave equation are found in theory, which represents a new family of ultrashort pulsed beams called ultrashort pulsed complex argument Sinc-Gaussian beams.

杨振峰 河北科技大学经济管理学院，石家庄 050018杨振军河北师范大学物理学院，石家庄 050016胡巍华南师范大学传输光学实验室，广州 510631利用理论解析推导的方法，在傍轴近似条件下，给出了一组新的超短脉冲光束的解析解，称为超短脉冲复宗量辛格高斯光束。

Papers analyzed the management flexibility and value of mining engineering, and set up the model of value of a developed mine,value of an undeveloped mine and value of an exploration project under the conditions of uncertainty with the theory of real option,and worked out the solution of model above-mentioned through three numerical methods,i.e.the Fig Tree,finite difference approximation and Monte Carlo simulation.

论文最后研究了矿业工程中的管理灵活性及其价值，运用实物期权方法分别建立了不确定条件下矿业生产阶段、开发阶段和详查、普查、预查阶段的矿业投资评价模型，并运用二叉树图、有限差分逼近和Monte Carlo模拟三种数值方法对所建模型进行了求解，同时通过实例对论文的研究结果进行了佐证。

The thermodynamic free energy on mixing and the Spinodal equation in ternary homopolymer blends were obtained by making plausible approximation based on Flory's equation of state theory.

本文运用Flory状态方程理论，对多元共混体系的热力学函数吉布斯共混自由能进行合理简化，并求得其Spinodal相图方程。

Variations of attenuation coefficients with rain rate for MP and LP model are compared under Mie theory and Rayleigh approximation. The approach to the solution of the Fourier integral in closed form is adopted for pulse propagation through rain medium .

在此基础上应用傅立叶时域积分近似解的方法研究了毫米波段脉冲波通过雨介质时，脉冲畸变随频率、降雨率、传播距离及脉冲宽度变化的关系。

Applying atomic many-body theory to analyse the Goldston diagrams of effective Hamiltonian and wave operator about electron-electron correlation for open shell atoms, we use a simple method to evaluate the effective Hamiltonian and calculate the correlation effectes of Corbon with HFS model as a zeroth order approximation. Making contrasts with the experiment and the calculation based on HF model we get pleased results.

应用原子多体理论对开壳层原子中电子关联效应的有效哈密顿量及波算符的Goldston图进行了分析，在此基础上得到了计算有效哈密顿量的简单方法；以HFS模型为零级近似对中性碳原子基态的关联效应进行了计算并通过与实验结果及其他文献基于HF模型进行的计算相比较，得到了令人满意的结论。

The infinite dimensional inverse problem was approximated by a problem in the finite dimensional space by using approximation theory.

将该算法应用于复杂函数的自动演化建模，也取得了理想的效果，因此该算法具有良好的通用性。

In this method,without depending upon small parameter,a trial function with possible unknowns is used as initial approximation,then a correction functional is constructed by means of a general Lagrange multiplier ,which can be identified via variational theory.

本文提出了一种求解非线性方程的迭代算法，它不依赖于小参数，是先给方程一个带待定函数的试函数作为初始近似解，然后用拉氏乘子法构造一个迭代公式。

Based on polynomial interpolation and approximation theory,a Chebyshev orthogonal basis neural network is constructed in this paper.

根据多项式插值和逼近理论构造一个切比雪夫正交基神经网络，其模型采用三层结构并以一组切比雪夫正交多项式函数作为隐层神经元的激励函数。

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。

According to the orthonormality of Legendre polynomials in the function approximation theory, the exact boundary of the ball Bézier surface was optimally squarely approximated in polynomial form.

依据函数逼近论中Legendre多项式的正交性，得到了采用多项式形式表示的球域Bézier曲面的精确边界的最佳平方逼近。

The changes of the HAF after liver injury may be related to the volume of blood loss, the intraabdominal pressure and the pneumoperitoneum duration.

肝撞击伤伴失血后肝动脉血流量的变化与失血量、气腹压力以及气腹持续时间等有密切联系。

Reneging on our commitments to the world's poor cannot be an austerity measure, she said.

放弃我们给世界上的穷国的承诺不能成为一种紧缩措施。