上微分

The interpolate algorithms of three-order NURBS curve and double three-orders NURBS surface are presented. The expressions of partial derivative and normal curvature of NURBS surface are derived by the theory of differential geometry. The geometric characteristics of different curvature area of the free-form surfaces are analyzed in detail. All these work lays a theoretical foundation for constructing the cutter location calculating model of free-form surfaces NC machining. 2 On the basis of analyzing the methods of cutter path generation, the standard of evaluating the various methods of cutter path generation is presented. The method of generating cutter path with constant scallop height is presented for the first time.

本文以提高复杂曲面多坐标数控加工精度和加工效率为目的，在对国内外研究现状进行深入分析的基础上，对数控编程中各环节的关键技术问题进行了深入研究，主要内容包括以下几方面： 1 分析了复杂曲面各种造型方法的优缺点，给出了根据各种边界条件所确定自由曲面的NURBS表示方法以及三次NURBS曲线曲面反算算法；用微分几何理论推导了NURBS曲面的偏导矢及法曲率计算表达式；对曲面不同曲率特性区域的几何特征进行了深入分析，为建立复杂曲面的数控加工刀位计算模型奠定了理论基础。

In recent years, the researches in mathematical biology which modeled by normal differential equations are mainly concentrated on two branches: 1 continuous biological dynamical systems; 2 impulsive semi-dynamical systems.

生物数学中以生物动力系统为基础的研究近年来得到了长足的发展，其中以微分方程为模型的研究工作主要集中在连续动力系统和脉冲动力系统上。

But the numerical differentiation process is very sensitive to even a small level of errors. In contrast it is expected that on average the numerical integration process is much less sensitive to errors.

在DQ方法的基础上，本文提出了一种新的方法——基于最高阶导函数插值的微分求积(differential quadrature method based on the highest derivative，简称DQIHD)方法。

Here mainly introduces five natures of the initial value problems, In several aspects summed up as the following : whether there are solutions to the problems, whether the only solution, the existence of solutions interval extent; Initial issues under what conditions have a solution--Cauchy - Piano existence theorem; how the district between the definition of a solution to open up a larger interval up; initial value problems for the sole condition --- Lipschitz conditions; 3、the numerical solution of the initial value problems of Ordinary Differential equations .

在这里主要介绍了初值问题的5个方面的性质，分别在这几个方面中总结了以下内容：初值问题是否有解，解是否惟1，解的存在区间有多大；初值问题在什么条件下有解----柯西-皮亚诺存在定理；怎样把在小区间上有定义的解开拓到较大的区间上去；初值问题解的惟1性条件---李普希茨条件；3：常微分方程初值问题的数值解法。

The method using microcomputer to draw the phase graph of autonomous system on plane of ordinarily differential equation is studied,first a large number of data of orbit are obtained by an appropriate method of numerical calculation from known initial condition,then computer draw the curve of orbit on screen by these data.

研究利用微机绘制常微分方程平面自治系统相图的方法，首先用一种合适的数值算法由已知的初始条件得到轨线的大量数据，再利用这些数据在计算机屏幕上画出轨线的图形。

From then on plenty of work had been done to research the periodic solution and stability of ordinary differential equation.

此后大量的工作研究常微分方程的周期解、稳定性，这在一定程度上解释了种群的共存、灭绝、持续生存。

However, the multi-time values before the initial time are required in solving the ordinary differential equation with linear multi-step method, the values at these time levels are still computed from the given initial value by one of above mentioned schemes.

在常微分方程的线性多步法中用到初始时次前若干时次的数值，但这些时次上的起动值仍然由初值运用方程计算得到的。这就是说，人们在预报问题中始终恪守只用一个初值的原则。在天气预报中，数值积分只用到一个起报场，即最后一个时次的观测场。

Kinetic equations of multibody systems with scleronomic constraint s are projected along the feasible and unfeasible directons of the constiaints respectively,and generalized accelerations of the systems are decomposed along the two directons using the bases of constraint matrix and its orthocomplement.

通过约束矩阵及其正交补的两组基，将定常约束多体系统的动力学方程沿与约束相容和不相容的两个方向上投影，并将系统的广义加速度沿这两个方向进行分解，得到描述系统运动的纯微分方程和求约束力的公式，同时提出了违约修正的一种方法。

In this paper, a general, strain-consistent, third-order displacement field of shells is proposed. On this basis, the nonlinear theory of composite laminated shells including third-order transverse shear deformation and rotary inertia is developed. Hamilton's variational principle is used to derive the nonlinear static and dynamic governing differential equations and the corresponding boundary conditions of composite laminated anisotropic general shells under the orthogonal curvilinear coordinates. And the form of spherical shells is degenerated.

本文提出了一种最普遍的应变协调、三阶壳体位移场，在此基础上建立了考虑三阶横向剪切变形和旋转惯性的复合材料层合壳体非线性理论，用Hamilton变分原理导出了复合材料层合各向异性任意壳体在正交曲线坐标系下的非线性静、动力控制微分方程和相应的边界条件，并将其蜕化为球壳形式。

The periodic oscillatory behavior is very important in the differential dynamical systems. Research on it is significant in theory and in practice.

周期振荡是微分动力系统中非常重要的现象，对于它的研究在理论和应用上都具有十分重要的意义。

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。