近似方法

Both viscous damping and air drag force must be introduced into the dynamic models. The experiment is carried out in the single-axis air-bearing test bed according to the experiment scheme in chapter 3. The results demonstrate the validity of the developed model, while the conventional zero-order approximate approach could lead to bad results for some high speed cases.

结果表明了传统零次近似方法在某些条件下已不能正确描述柔性体的刚柔耦合动力学性质，而一次近似的刚柔耦合动力学模型得到的结果与实验相符，从而证实了一次近似耦合模型的正确性和可靠性。

The WKB approximate method is one of effective approximate methods in the quantum mechanics .

WKB近似方法是量子力学中有效的近似方法之一。

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。

First of all,we have given some of the basic concepts of differential equations, described the constant coefficient linear ordinary differential equation solution, for a class of second-order variable coefficient linear ordinary differential equation initial value problem, an approximate solution, the method is first unknown function of a definition for N sub-interval, and then in between each district within a constant coefficient ordinary differential equations similar to the replacement, the solution has been the problem as similar to the original analytical solution, and then gives a detailed second-order change order coefficient of linear homogeneous ordinary differential equation solution examples, the examples of the approximate method proposed in this paper is valid.

首先给出了微分方程的一些基本概念，讲述了常系数线性常微分方程的解法，针对一类二阶变系数线性常微分方程初值问题，提出了一个近似解法，本方法是先对未知函数的一个定义区间作N等分，然后在每一个小区间内用一个常系数常微分方程近似替换，所得到的解作为原问题的近似解析解，随后详细给出了一个求二阶变系数齐次线性常微分方程的解的实例，该实例说明本文提出的近似方法是有效的。

The main work of the thesis consists of summarizing the characteristics of the approximation methods,compiling the programs of approximation methods,and getting availability of every approximation method according to examples.

本文的主要工作是总结各种近似方法的特点，编写各近似方法的程序，通过算例总结出各种近似方法的适用性。

The system is controlled by continuous review installation stock policies. This paper presents an improved approximated method that the leadtime demand of warehouse is approximated by the normal distribution, and the leadtimes demand of retailers are approximated based on negative binomial distribution.

论文给出改进的近似方法，即用正态分布近似分销中心提前期内需求的分布，用更符合实际的负二项分布近似零售商提前期内需求分布，从而建立了二级分销系统期望总成本近似模型。

The fields radiated by these currents in the presence of curved earth are then calculated using the reciprocity theorem and the known ground wave propagation formula of a vertical electric dipole S.

在数值结果验证了该公式的正确性之后，对海面上一金属半球的散射场进行了求解，并以此与工程应用中的近似方法相对比，考察了工程应用方法的近似程度。

Two different approaches, namely, the mode matching approach and the partial Fourier transformation of the Lippmann-Schwinger equation approach, have been employed to cross check our results.

我们使用了两种不同的方法、模态匹配近似法及Lippmann-Schwinger方程式的部分富立叶转换近似方法、来交互比对确定我们的结果。

In this paper we have studied the Upper bound for the time derivative of information entropy for a dynamical system driven by colored cross-correlated colored noises. The Fokker-Planck equation was obtained by using the unified colored noise approximation. The upper bound for the rate of entropy change can be calculated explicitly based on the definition of Shannon's information entropy and the Schwartz inequality principle.

" T！ z2 r" j0 S0 F5 J* T 摘要：本文研究了一种由色关联乘性和加性色噪声驱动的随机耗散动力学系统随时间演化的熵变化率上界，通过统一色噪声近似方法给出了该系统的近似Fokker-Planck方程，然后结合Shannon信息熵的定义及Schwartz不等式原理给出了该系统经近似后熵变化率上界随时间演化的精确表达式。

The direct calculation of the GaN/AlN super cell demonstrated that the GaN/AlN heterojunction was homotype and changed abruptly at the interface.

另外，通过使用常用的平均键能法、平均势法和芯态法三种近似方法对GaN/AlN带阶的计算，比较得出，超原胞法虽然计算量较大，但能够给出异质结界面附近更为详细的信息，这一点其他三种近似方法无法得到，但他们也能够得出与实验值基本一致的带阶参数。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。