查询词典 approximate differential

Using the method we calculate the 〓 elasticdifferential scattering cross section, excitation differential scattering crosssection, and excitation cross section of electron collision with 〓 We transform the electron and molecule problem into electron problemby Born-Oppenheimer approximate. Mr Rossi, Dr. the Flinders University ofSouth Australia, calculated electron collision with molecule, but theexchange term he used become bigger and bigger as incident energyincreases, it is unreasonable, besides, the potential of electron and nucleus heused is somewhat rough. At present we correct these two terms. The potentialconsists of static potential, exchange potential, polarization potential.

电子与分子的碰撞过程的相互作用势主要是由静态势、交换势和极化势三部分决定的，这里对这三部分在动量空间中进行分波展开，推导出易于计算的表达形式，根据这些公式，并参考Rossi的弹性碰撞程序编写了计算电子与分子碰撞激发截面的程序，利用程序计算出势能矩阵元，通过求解Lippmann-Schwinger方程求得T矩阵元，便可求得散射截面。

On the basis of introducing the fixed point of Banach theorem, this paper firstly elaborates the important application of the existence of the solution of the linear algebraic equation and the ordinary differential equation, then it narrates the important application of obtaining the leading Newton repetitive process and the natural number the inferior square root and the equation root in the approximate calculation.

本文在介绍Banach不动点定理的基础上，首先阐述了其在线形代数方程、常微分方程解的存在性中的重要应用；然后讲述了其在求导Newton迭代法、求自然数的次平方根、求方程根的近似计算中的重要应用；最后，介绍了其在求一类递推数列极限中的应用。

For first-order linear DPS with spatial-varying coefficient matrices a method is presented to approximate the system piecewisely by N partial differential equations with constant coefficient matrices.

它包括两大部分，一是关于分布参数系统的频率域数学描述即传递函数这一基本问题的应用研究，二是关于一类用多滞后型传递函数表示的分布系统的控制设计问题。

In the point reactor model, the probability function(n, t0, t) of a source neutron at time t0 leading to n neutrons at time t is dealt with. The non-linear partial differential equation for the probability generating function G(z; t0, t) is derived. By solving the equation, we have obtained an approximate analytic solution for a slightly prompt supercritical sys tem.

在点堆模型基础上，考虑了在t0时刻系统引入一个源中子，在t时刻产生n个中子的概率(n， t0， t)推导了概率生成函数G(z； t0， t)所满足的偏微分方程，并得到了近似解。

The value solution adopts "the step-type" format to solve separate lights for the approximate value. The Euler method and the Runge—Kutta method are the most typical commonly value method to solve the differential equation.

数值解法采取"步进式"的方式求解离散点上的近似值，欧拉方法和龙格——库塔方法是求解微分方程最典型常用的数值方法。

The major implementations of the developed model include: Pseudo-spectral and finite-difference schemes are employed to approximate the spatial-differential operators in the horizontal and vertical directions, respectively. A second-order Runge-Kutta method is adopted to integrate in time for the velocity field and the free-surface elevation. The solenoidal condition of the velocity field is satisfied by solving the transformed pressure Poisson equation. A modified secant method is used to accelerate the iterative solution of the non-separable Poisson equation.

模式的主要数值方法包括：分别以拟频谱法以及二阶有限差分法近似控制方程与边界条件中的水平与垂直导数；以二阶Runge-Kutta法进行非稳态的自由液面位移与流场速度的时间积分；利用改良式割线叠代法求解计算区间中不可分离的压力Poisson方程式，以满足不可压缩流条件。

A variational method with differential forms gives better precision for numerical solution of transport critical problem based on spherical geometry, and its computation seems simple than other approximate methods.

对于球几何问题，讨论了一种基于微分方程的变分形式求解方法，数值计算显示达到了较满意的精度，而且计算过程比起其他近似方法要简单

Nonlinear partial differential dynamic equations of bending vibration of a tilting stepped drive shaft with two supports were built under non-inertia movement coordinate system by theorem of the motion of mass center and Heaviside function. According to the condition of equal displacement in an adjoining plane of the shaft, an equivalent shaft and its equation were obtained. A motion equation of the equivalent shaft was obtained by method of Galerkin. An approximate steady-state solution of the main resonance was obtained by method of multiple scales. The influence factors, motion stability, amplitude jump of main resonance of a stepped drive shaft and so on were analyzed.

用质心运动定理、Heaviside函数建立了非惯性系下倾料两端支承阶梯传动轴的非线性弯曲振动偏微分动力学方程，并根据相邻轴段的衔接面处位移相等的条件，得到阶梯轴的当量轴及其动力学方程；用Galerkin法得到当量轴的弯曲运动方程，用多尺度法求得稳态下当量轴的主共振的一次近似定常解，分析了影响阶梯传动轴主共振的因素、运动稳定性、振幅突变性等。

This dissertation is changed into two parts. The first part, the theory and application about Wu-Ritt differential characteristic sequence method are discussed, which involves the theories of differential equations, abstract algebra and computer algebra etc.

本文共分两部分，第一部分讨论微分特征列法的理论和应用问题，涉及到微分方程，抽象代数，计算机代数等重要学科。

In this paper, the adjointness of the product of two differential operators generated by a third order normal and singular symmetric differential expression in the limit-circle case is discussed. The necessary and sufficient conditions which make the product operators being the adjoint operators obtained by the matrix analysis and calculation. At the same time, the adjointness of the product of the power and adjointness operator obtained.

本文首先讨论了正则和奇异两种情况下两个极限圆型三阶对称微分算式生成的微分算子的乘积的自共轭性，运用矩阵分析和计算，得到了乘积算子为自共轭算子时边界应满足的充分必要条件，同时得到了幂算子的自共轭性、自共轭算子乘积的自共轭性等乘积算子的其它若干性质。

A historical region of southwest France between the Pyrenees and the Garonne River. The duchy of Aquitaine was joined with France after the marriage of Eleanor of Aquitaine to King Louis VII in1137, but its possession was disputed after her subsequent marriage to Henry II of England.

阿基坦法国西南部一个历史地区，位于比利牛斯山和加隆河之间，在1137年阿基坦的埃莉诺与国王路易斯七世结婚之后阿基坦公国加入法国，但当她再嫁英国亨利二世后，其归属权便受到争议

There are moments when I look at the smiling , happy faces of my expectant staff and wonder how they will cope when confronted by an outraged housemaster along with an unrepentant and recalcitrant bleached blond teenager in 18 years ' time .

有时候，我看着那些满怀期待的员工微笑，幸福的脸，想着当他们遇到一位愤怒的宿舍管理员和一位不知悔改，叛逆，而且将头发染成白色的18岁少年时，他们会如何处理。