查询词典 approximation theorem

Two-dimensional Bernstein type operators on simplex are constructed, and a necessary and sufficient condition of uniform approximation by mem is obtained, at the same time, the degree of approximation is characterized by two-order moduli of smoothness.

并且构造出单纯形上推广的二元Bernstein型算子，给出其一致收敛的一个充要条件，同时用二阶连续模刻划了它们的逼近度性质。

In this chapter we discussed the existence,uniqueness and approximation degree of binary cubic splines with C~2 connectivity for type-Ⅱtriangulations on rectangular domain,and we also gave a analysis of approximation of the interpolation splines.

本文还研究了二元三次样条函数在曲面重建中的应用问题，在TYPE-Ⅱ型剖分下，对于三次样条插值曲面的C~1-拼接问题，许多学者在这方面展开了大量的研究

In order to validate the correctness, the absolute differential cross sections of e-Ar scattering with multi-photon exchange in some special scattering geometries are calculated with Yukawa potential by applying the Second-order Born approximation and low-frequency approximation theory, respectively.

为了验证该计算方法的有效性，在入射电子的动量平行于激光场的极化方向这种特殊的散射模式下，利用Yukawa势，分别应用二阶玻恩近似方法和低频近似理论方法对激光场中电子—氩原子交换不同光子数的散射截面都进行了计算。

Bonikowskis model, the covering upper approximation operation and covering lower approximation operation are not dual to each other. William Zhu proved them determining each other, but he cannot give the quantity relation of them.

Bonikowski定义的广义覆盖粗糙集模型中，上近似算子与下近似算子不满足对偶的性质，虽然William Zhu等证明了上、下近似算子是相互确定的，但是没有给出它们之间具体的数量关系。

In chapter 2, basic knowledge of the rough set theory, such as indiscernibilityrelation, elementary set, approximate space, upper approximation, lower approximation, negative region, boundary region, rough set, etc., and algebraic properties of rough set are introduced. At the same time, the feature of the rough, set theory is also introduced.

第二章介绍了粗糙集理论基本知识，如不可分辨关系、基本集、近似空间、上近似、下近似、负域、边界域、粗糙集等概念，以及粗糙集的代数性质，同时还介绍了粗糙集理论的特点。

In rough-set theoretic sense,the histogram correlates with the lower approximation and encrustation of histogram correlates with upper approximation.

从粗糙集理论意义上来说，直方图的外层与上近似有关，而直方图取值与下近似有关。

By virtue of a two-mode approximation and a rotating-wave approximation, an exact solution of the system is given.

利用双模近似和旋转波近似，得到了系统的精确解。

The finite difference approximation for this equation is presented.The stability and convergence of the finite difference approximation are analyzed.

并证明了显式格式条件稳定和条件收敛，而隐式格式则是无条件稳定和无条件收敛。

In order to solve the problem,starting from the analysis of the simplest plane wave numerical theory,we derived the formula of relative phase velocity and group velocity under the condition of arbitrary high-order finite-difference approximation,and gave the computational method for acquiring the optimum Courant number,and then analyzed the anisotropic effects due to finite difference approximation.

针对此，从最简单的平面波数值理论分析出发，推导了任意高阶有限差分近似条件下相对相速度和相对群速度的计算公式，给出了求解最佳Courant数的计算方法，分析了差分近似造成的各向异性效应。

College of Guandong Business, Guanzhou 510320, China）Abstract: Since large-scale vertical quench furnace is voluminous, whose working condition is a typically complex process with distributed parameter, nonlinear, multi-inputs/multi-outputs, close coupled variables, etc, dynamically decoupling control algorithm of temperature distributed parameter system in the furnace was presented, by which the whole system was decoupled to several subsystems and the implementation of controller was simplified. With finite difference approximation, the space and time step size was solved to ensure the convergency of finite difference approximation. After decoupling, the subsystems were controlled with self-learning PID control algorithm. The results show that the temperature control precision and homogeneity are improved; the overshoot and process in temperature rising period are reduced simultaneity.

摘 要：针对大型立式淬火炉体积庞大，工况复杂，炉内温度分布呈本征非均匀性，具有多输入/多输出、非线性、强耦合等特性，难以实现炉内温度高精度高均匀性控制目标等问题，提出一种温度分布参数系统动态解耦控制算法，其原理是：采用有限维逼近方法将对象解耦为多个独立的子系统，简化控制器的实现过程；通过分析有限维逼近方法的收敛性，获得保证收敛性的空间和时间步长应满足的条件；解耦后的子系统采用自学习PID控制算法，实现炉内温度高精度和高均匀性控制以及升温过程的快速性和小超调。

"The operators will suffer a temporary decrease in the number of consumers and short message services as people may not like having to provide their ID cards for a phone number," Xu Junqi, vice-dean with the Policy-Making Institute of the Telecommunications Research Centre under MII, said yesterday.

信息产业部下属的通信决策研究院副主任徐俊其昨天说：&实行手机实名制后，人们可能不太情愿用身份证注册手机号，所以通信运营商会暂时面临用户减少和短信用户减少的问题。&

I don't believe in make-believe!

我不相信这些虚构的故事。