数值微分法

Based on the equilibrium equation of an arch element the cubic nonlinear dynamic model with second order is established and the nonlinear differential dynamic system without constant term is obtained through a transfer process of T=U+b. Hence three fixed points and the homoclinic orbits are found. The critical condition of the chaotic vibration of the elastic arch is given by using the method of Melnikov function. The numerical results of the stationary and chaotic motion are given and discussed.

首先利用拱的单元平衡方程建立了拱的二阶三次非线性动力学模型；然后通过变换使方程转化为不含常数项的非线性微分动力系统，并由此得到无扰动系统的3个不动点与同宿轨道；再用Melnikov函数法给出了发生混沌的临界条件；最后给出了该系统出现定常运动和混沌运动的数值结果。

In this part, the characteristics of transient responses of flexible rotor systems with arbitrarily distributed mass on isotropic or anisotropic supports passing through several critical speeds seguencially are examined. Here, the current knowledge of rotor dynamics on the eigenproblem of damped free whirling vibration, the generaliged damped mode theary, the transient forced vibration and so on combined with KBM asymptotic method in the nonlinear vibration theory is employed and extended.

作者综合运用并引伸推广转子动力学关于阻尼自由回旋振动的特征问题、广义阻尼模态理论、瞬态强廹振动等現代理论和方法，结合非线性振动理论中的KBM渐近法，提出自己独創見解和覌点，成功地建立起正回旋和逆回旋两种情况下转子通过临界点的瞬态振动一阶微分方程组，可以在临界点的邻域内从事方程的数值积分计算。

It is used to solve the discretized equation which is derived by EFGM.

精细积分法是求解常微分方程的一种成熟的数值算法。

Meshless method is a new numerical method on problem for determining solution of differential equation.

无网格法是求解微分方程定解问题的一种新数值方法。

Then the basic fundamental and method of the computation of thermal load of the heated parts of internal-combustion engine are elaborated, the deflective differential equation of heat conduction, basic equation and boundary condition of the theory of thermo elasticity and numerical computation by FEA are introduced.

接着阐述了求解内燃机受热零部件热负荷的基本原理和方法，介绍了热传导的偏微分方程、热弹性理论的基本方程和边界条件确定的原则以及用有限元法进行的数值求解。

The functional by variational calculus leads to a set of elliptic partial differential equations,in particular,Poisson equations,which is possibly solved by numerical methods.

利用变分法可以从这个二次误差指标函数导出一组椭圆形偏微分方程泊松方程，这类方程有相当成熟的数值解法。

The spectral element method, which combines the high-order precision of spectral methods and the geometrical flexibility of finite element methods, has achieved great success and is becoming a useful tool for investigation of such equations.

谱元法作为一种高阶的数值方法，结合了谱方法的高精度和有限元法灵活的网格剖分技术，在不可压流体的计算中已取得了很大的成功，并正成为计算随机微分方程的一个有力工具。

Inverse M-matrices often occur in relation to systems of linear or non-linear equations or eigenvalues problems in a wide variety of areas including finite difference methods for partial differential equations, input-output production and growth model in economics, iterative methods in numerical analysis, and Markov processes in probability and statistics.

其中包括偏微分方程的有限差分法、经济中的投入产出和增长模型、数值分析中的迭代法以及概率论和数理统计中的马尔可夫过程。

The author successfully applies the Gauss-type integral formula to the numerical solution to the constant differential equation and creates the Gauss-type implicit Runge-Kutta Method of which the accuracy of order 4 and degree 7 is already equivalent to that of the RK method with order 10 and degree 8 that is in common use.

成功地将高斯型求积公式用于常微分方程的数值解中，得到了高斯型隐式龙格库塔方法，4级7阶 GRK 法的精度已与目前较为常用的10级8阶 RK 法的精度相当。

The author systematically studies the construction principle of high order accuracy difference scheme and uses third-order accuracy Godunov scheme with TVD property to solve three-dimensional viscous flow field in cascade.

为了减少网格畸变对数值解的影响，发展了一种微分方程法与代数法相结合的网格生成方法。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。