查询词典 approximate differential

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。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。