查询词典 approximation

Exact formulae for bit error probabilities of the considered system are derived, and a set of numerical results both for the exact formulae and Gaussian approximation are presented.

分析并得出了系统位错概率的数学模型，并给出了该模型和高斯近似模型的一系列数值仿真结果。

Set cover greedy algorithm is one of the commonly used algorithms for the test set problem. It is an open problem if the approximation ratio 2ln n+1 directly derived from the set cover problem can be improved.

集合覆盖贪心算法是测试集问题的一个常用近似算法，其由集合覆盖问题得到的近似比21nn+1能否改进是一个公开的问题。

Meshless method is a new numerical method on problem for determining solution of differential equation. It is an approximation method based on nodes, and doesn't need a mesh entirely or partly. Then the discontinuous problems and the extremely large deformations problems can be solved without the re-meshing techniques.

无网格方法是求解微分方程定解问题的一种新数值方法，它采用基于点的近似，可以彻底或部分地消除网格，因此在处理不连续和大变形问题时可以完全抛开网格重构。

Under small-scattering approximation the diffraction integral equation for determining distribution of diffracted light field is presented. Comparision is made with coupled wave theory and K.

本文首次将不均匀物体对光的散射过程引入到体全息图对再现光的衍射过程，在小信号近似下获得了衍射光场分布的积分方程，并与耦合波理论及K。

Meshless method is a new numerical method on problem for determining solution of partial differential equation. It is an approximation method based on nodes, and doesn't need a mesh entirely or partly. Then the discontinuous problems, the extremely large deformations problems, and movable boundary problems, etc, can be solved by use to meshless without the re-meshing techniques. And not only the calculated precision can be guaranteed, but also the calculated difficulty can be decreased.

无网格方法是求解微分方程定解问题的一种新的数值方法，它采用基于点的近似，可以彻底或部分地消除网格，因此在处理不连续、大变形、移动边界等问题时可以完全抛开网格重构，不仅可以保证计算的精度，而且可以减少计算难度。

Finally, the complex surfaces are developed by partition of the surfaces into small surface segment ,and approximation of the small segment with the developable surface between two Bezier curves.

最后，采用分片与近似的思想，给出了复杂曲面展开的算法，并提出由曲面面积和曲面展开面积的相对误差调节分片程度来满足精度要求。

There are two parts in this dissertation. In part one, the reaction scattering for the H3 system is studied using three-dimensional quantum mechanical coupled channel distorted wave approximation. In part two, a new form is proposed for interaction between an atom and a diatomic molecule.

本文分两部分：第一部分用三维量子力学耦合通道扭曲波方法研究了三氢系统的反应散射；第二部分提出了一种原子与双原子分子相互作用的新形式。

Aim To investigate the dispersion relation of one-dimensional diatomic chain, and compared with the results of nearest neighbor approximation.

目的 研究一维双原子链的色散关系，并与最近邻近似下的结果进行比较。

The difference schema of the initial boundary value problem was converted to the step-by-step form,which was similar to the difference schema of the initial value problem.It is concluded that the difference schema satisfying the Von Neumann condition is a stable schema,and that,under the consistency condition,such stable schema is convergent.Moreover,with error estimate expression for the difference approximation to the classical solution,the linearity condition is unnecessary.

引入反投影算子将发展方程初边值问题的差分格式转化为与初值问题差分格式类似的逐步推进的形式，从而得出：满足Von Neumann条件的差分格式是稳定的格式；在相容条件下，差分格式若稳定(或满足VonNeumann条件)则格式收敛，且对古典解的差分逼近有误差估计式，不再需要线性的条件。

In Chapter 2, starting from the basic fractional ordinary differential equations,weapply a high order approximation of fractional derivative advanced by Lubich to frac-tional differential equation, construct a high numerical difference scheme to solve thefractional differential equation, present error analysis of the algorithms theoretically,and prove the consistency ,convergency and stability.

接下来的第二章中，首先从基本的分数阶常微分方程出发，对Lubich提出的一个关于分数阶导数的高阶近似，将其应用于分数阶微分方程，构造高阶数值差分格式来进行分数阶微分方程的数值求解，并在理论上给出这一算法的误差分析，证明了它的相容性，收敛性和稳定性。

For the head-teacher of the class said that I had seriously broken the school rules,which led me to a three-day suspend class.

为什么呢？因为我的班主任说我严重的违反了校规，于是让我停课三天。

Many of them believe that the conversion of thousands of working-class folk in England spared that nation from the mass carnage and the tyranny that came with the revolution in France.

他们之中有许多人相信，在英国数以千计的劳工阶级之悔改信主使英国免於遭受如法国大革命所造成的大屠杀和专制暴政。