查询词典 approximation theorem

The fine structure Hamiltonian for Hydrogen-like atoms is derived using the nonrelativistic approximation of the Dirac equation for one electron moving in the Coulomb field.

从Coulomb场中运动的电子的Dirac方程出发，取其非相对论极限导出了类氢离子的精细结构哈密顿的表达式。

A parallel algorithm for certain real symmetric block-tridiagonal linear systems on distributed-memory multicomputers is proposed. This algorithm is based on the block factorization of the coefficient matrix. This algorithm is used to solving the block-tridiagonal linear systems resulted from the finite difference approximation to Poisson's equation with Dirichlet boundary conditions. Then we get a parallel algorithm which speedup tends to linear speedup.

7研究了一类实对称块三对角线性方程组的分布式并行求解，提出了一种基于块矩阵分解的高效分布式并行算法，将其应用于求解带Dirichlet边界条件的Poisson方程导出的块三对角线性方程组，得到加速比趋于线性加速比的分布式并行算法，理论上说，这也是并行算法的理想情况。

He could travel with an approximation of ease if not enjoyment in the class that disconcerted him.

他与同他步调不一致的人外出时，即使感到不快也能做到近乎坦荡。

The kernel is adding a discontinuous function for the standard approximation to account for the crack. A feasible technique is adopted for dealing with multiple cracks and intersecting cracks.

本文研究扩展有限元方法，通过改进标准有限元的单元逼近函数，使之能够表达单元内的几何不连续，从而实现切割和断裂的模拟。

This makes more and more people pay more attention to studies and applications of numerical simulation in thermal recovery. In this research, we have developed a reliable mathematical model for thermal recovery, which takes a full consideration of the effect of viscos, gravitical and capillary forces on the three-phase flow of gas, water and oil, the effect of the temperature on the medium characteristics of liquid and solid, the phase equilibrium of gas-liquid in each component, heat transportation including connection, conduction and radiation as well as heat losses in both the overburn and underlying strata. In the space discreation of the mathematical model, we have proposed a new method based on the improvement of the conventional nine-points difference approximation, which has a higher difference accurancy.

本项研究以热力采油的主要机理为基础，充分考虑在粘性力、重力和毛管力作用下油水气三相流动，考虑温度对各种流体和固体介质物性的影响，考虑每一组分中汽液两相的相平衡，考虑热在地层中的传导、对流和辐射以及上下盖层的热损失，利用热力学第一定律、质量守恒定律和流体迁移定律，建立了正确可靠的注蒸汽数学模型；在对数学模型进行空间离散时，利用控制有限体积积分法，对以往的九点差分近似作了合理的改进，使其具有较高的差分近似精度：结果表明，该公式的近似精度要比以往文献中所给的九点差分近似精度高，可以认为，在油藏数值模拟中，如果遇到非均质情况，使用这种九点差分近似更合理。

In this paper,the authors give a strict proof of geometric Brown motion displayed by stock prices using the methods of approximation from discrete process to continuous stochastic process.

通过由一般的离散过程逼近连续随机过程的方法，给予证券价格按有漂移率的几何布朗运动变化的一个严格的证明，并指出了股票价格过程的一般模型

Periodical interference can be represented in a good approximation with a discrete Fourier series.

这类干扰信号的频率若落在有用信号的频谱范围之内，用频域处理方法则很难将其单独消除。

Among these methods, it is surprising that few if any fundamental treatments of decoherence exist that include the dynamics of disentanglement with better than the Markovian approximation or phenomenological tradition.

所以研究环境对量子系统的影响，以便减缓环境对其包围下的量子系统的耗散、退相干、退纠缠等负面作用，就成为当今非常重要的课题。

Using the adiabatic approximation, the expression of the mean dissipative force are acquired.

利用绝热近似，给出了平均辐射压力的表达式。

Utilizing the linear approximation lemma, we construct one distinguisher to distinguish the weak Key-IVs for each Grain version.

虽然弱Key-Ⅳ出现的概率很低，但可以说明这两个算法的密钥初始化过程存在安全问题，有必要进行修改。

Tom: You are right, he worked hard all the time.

你是对的。他一直都是努力工作。

Take shortcomings,failures,and mockings of others as commonplace and a drive to complete oneself,hold your own opinion over the evalution and disscution divested from others,afterwards sink into the state of eliminate mistakes if any or encourge oneself being not being influenced by the sayinngs of others or having no ideas to do.

把缺点、失败及别人的耻笑等看成是一种常事，当成完善自己的动力，对别人的评价和议论自己心中有主见，做到&有则改之，无则加勉&，不为人言所左右或无所适从。