阶式控制

By adopting the asymptotic expansion method, the higher order partial differential equation was transformed into the system of ordinary differential equations.

采用渐近展开法，将该控制方程——高阶偏微分方程转化为常微分方程组，求解该方程组获得应力函数，进而得到功能梯度材料中裂纹尖端应力高阶渐近场的解析式。

The topics to be covered in the course are Integration and Economics Applications, Linear, First-Order Difference Equations, Nonlinear First-Order Difference Equations, Linear Second-Order Difference Equations, Linear First-Order Differential Equations, Nonlinear First-Order Differential Equations, Linear Second-Order Differential Equations, Simultaneous Systems of Differential and Difference Equations, and Optimal Control Theory.

讲授内容包括积分与经济的应用、线性一阶差分方程式、非线性一阶差分方程式、线性二阶差分方程式、线性一阶微分方程式、非线性一阶微分方程式、线性二阶微分方程式、差分与微分的联立方程式、最适控制理论。

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。

Two above methods are generalized to tensor product Bézier surfaces and triangular Bézier surfaces, we give two approaches of degree reduction for tensor product Bézier surfaces, each of which reduces a given degree n×m tensor product Bézier surface to a n〓×m〓 one, and two methods of degree reduction for triangular Bézier surfaces, which reduce a given degree n triangular Bézier surface to a degree m one. The explicit formulas of control points for reduced tensor product and triangular Bézier surfaces are obtained respectively.

张量积Bézier曲面的两种降阶方法均可把n×m阶张量积Bézier曲面一次降阶为n〓×m〓阶张量积Bézier曲面；三角Bézier曲面的两种降阶方法均可把n阶三角Bézier曲面一次降阶为m阶三角Bézier曲面，并给出降阶张量积Bézier曲面和降阶三角Bézier曲面控制顶点的显示表示式。

Nozzle flow was assumed to be frozen, and convective and radiative heat transfer from gas to solid wall was considered. Discretization of the governing equations was performed with two order upstream scheme, and radiative heat transfer equation was solved with Discrete Ordinates method. Absorption coefficient of water vapor was calculated by Leckner formula.

计算中，假定塞式喷管中的流动为冻结流动，考虑燃气向壁面的对流换热和辐射换热；采用二阶迎风格式离散控制方程，及DO模型离散求解辐射换热方程，水蒸气的吸收系数根据Leckner公式计算。

In the process of degree reduction, two cases are considered respectively. One is the case without conditions of endpoints interpolations.

两种方法均考虑了不带端点插值条件和具有端点高阶插值条件的情形，并给出降阶Bézier曲线控制顶点的显示表示式。

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。