数值方法

Finally, the idea of using new numerical method such as Discontinuous Deformation Analysis and Numerical Manifold Method to simulate the joint of CFRD is proposed, which can make guidance on the design and calculation of CFRD built on thick alluvium deposits.

提出引进新的数值方法，如不连续变形分析方法和数值流形方法，来模拟和计算面板坝接缝变形的设想，对深覆盖层上面板堆石坝的设计和计算有指导意义。

This semi-analytical method is accurate and widely used. It overcomes the limitation of the analytical solution such as conformal mapping. The position of cracks can be arbitrary.

这种解析数值相结合求解应力强度因子的方法，充分利用了解析方法精度高和数值方法适用性广的特点，同时又克服了保角变换等解析解的局限，各裂纹位置可以是任意的。

By applying contour integral method and high-order displacement functionsof MM,we obtain the accurate stress intensity factors of mixed-mode crack.Then,the open crack propagation of the mixed mode I and II is simulated by means oftheories of linear elastic fracture mechanics.This provides a simple and effectivenumerical way for crack evolvement studying.

接着，文中采用围线积分法和流形方法的高阶位移函数来计算得到比较准确的混合型裂纹尖端的应力强度因子，然后基于线弹性断裂力学的裂纹扩展准则，用流形方法实现了平面I-II混合型张裂纹扩展的数值模拟，为数值方法研究裂纹的演化行为提供了一条简单而有效的途径。

In this paper, we construct the differential equation to solve the unconstrained optimization problem. Such methods solving the ill-conditioned problems are very effective. It indicates that the asymptotically stable region of explicit the Euler method to solve the differential equation equals to the descent region of the gradient method to solve the original unconstrained optimization problem.

我们发现，在用Euler方法求解二次优化问题的等价动力系统的方程时，由方法的步长确定的稳定区域对应于这些方法所得到的迭代公式的步长满足单调下降算法的条件确定的单调下降区域，因此我们可以利用这个性质构造解无约束优化问题的数值方法而不采用标准的常微分方程的数值求解公式。

In this paper,taking advantage of some properties of Gamma function,we get the explicit solution. Some simulation results are also given in this paper. In chapter three, we discuss the problem under censored data in three circumstances.

一直以来，对Weibull分布参数的矩估计都是采用数值方法求解，本文利用Gamma函数的一些性质，得到了估计的显式解，并从理论和数值模拟说明此种方法相比其它方法的优越性。

In order to reasonably depict four basic problems with friction, one Coulomb friction new form in first Kirchhoff stress is proposed to deal with finite deformation problems, other Coulomb friction form in incremental mode to elastoplastic flow theory; Hilbert function spaces concerning elastoplastical problems with friction are established, so it makes all operations and calculations in the treatise standardized within the scope of reasonably topologic structure; In view of functional extremum, the equivalence between generalized variational inequalities principles in elastoplasticity with friction and corresponding basic problems are testified by inducing Lagrangian multipliers, so it provides a rationally theoretical basis for numerical methods in elastoplasticity with friction; From the viewpoint of variational inequality, the theory of generalized variational inequalities in elasticity and elastoplasticity with frictional constraint is studied, and the uniqueness and existence of the solution of FEM is proofed under the proposed conditions of stress compatibility, and them FEM approximation and a discrete solution are discussed; Based on the principles of generalized variational inequalities in elastoplasticity with friction, direct generalized variational inequalities methods is pretended, which is a natural generalization and development of direct variational methods; Using generalized variational inequalities methods, some examples in metal forming including plane deformation, upset and extrusion are analyzed and the results prove that all the theories and methods in the paper are right, feasible, accurate and advanced.

主要内容有：为了合理地描述金属塑性成形中摩擦约束弹性、弹塑性基本问题，提出和研究了有限变形下以Kirchhoff第一应力表示的Coulomb摩擦定律形式和弹塑性流动理论下以增量形式表示的Coulomb摩擦定律表示形式；系统建立了摩擦约束弹塑性问题的Hilbert函数空间，使本文规范在一个具有合理的代数拓扑结构内进行一切操作和运算；利用Lagrange乘子，从泛函极值的角度系统地阐述和论证了一系列摩擦约束弹性、弹塑性广义变分不等原理与相应的实际问题之间的等价性，它为处理摩擦约束的弹塑性力学数值方法提供了合理的理论基础；从变分不等式的角度出发，阐述了对应于摩擦约束弹性、弹塑性问题的广义变分不等式理论，首次提出了在应力相容性条件下，它的有限元解具有存在唯一性，进而讨论了其有限元近似及离散解法；基于摩擦约束弹塑性广义变分不等式原理，首次提出了直接广义变分不等式方法，这一方法是直接变分法的合理推广和发展；利用直接广义变分不等式方法对金属压力加工中的平面变形问题、镦粗、挤压等塑性成形问题进行了分析计算，验证了该理论和数值算法的正确性、实用性、精确性和优越性。

In the computational methods of TPBVP, in order to reduce some difficulties involved in solving a TPBVP via adjoint variables, we discuss a direct method in which state and control variables are indirectly parameterized, The method employs a recently developed direct optimization technique that uses a piecewise polynomial representation for the state and control variables, thus converting the optimal control problem into a nonlinear programming problem, which can be solved numerically.

在数值解法中，为了减少解决两点边值问题共轭变量带来的困难，主要讨论了将状态变量和控制变量进行参数化的一种直接方法，这种方法采用了近段发展起来的使用分段的多项式来代替状态和控制变量的直接优化方法，然后最优控制问题就转化成可以用数值方法解决的非线性规划问题，使得迭代初值更加容易选取。

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。

However, numerical modeling for nonlinear seismic waves is faced with problems such as steep gradients, shocks and unphysical oscillations. Accordingly, some special treatments have been presented to solve these problems. However, in our knowledge, there is no effective method to overcome these problems by far.

非线性弹性波的数值模拟存在陡峭间断面、数值振荡以及误差的指数级增长等现象而破坏数值解的稳定性、收敛性，能否消减上述现象的不利影响成为制约数值方法有效与否的重要因素。

We present our Monte Carlo results of the random-bond Potts ferromagnet with the Olson-Young self-dual distribution of quenched disorders in two dimensions.By exploring the short-time scaling dynamics,we find the universal power-law critical behavior of the magnetization and Binder cumulant at the critical point,and thus obtain estimates of the dynamic expontent z and magnetic exponent η,as well as the exponent θ.Our special attention is paid to the dynamic process for the q=8 Potts model.

以蒙特卡罗模拟方法对自对耦分布二维随机链q态Potts模型的短时临界行为进行了数值研究，利用初始非平衡演化阶段存在的普适幂指数和有限体积标度行为，数值模拟了在不同形式随机分布时q=3和q=8态Potts模型磁临界指数η和动力学临界指数z，计算结果发现η不依赖于自对偶无序分布的具体形式，从而以数值方法给出了一个关于淬火掺杂自旋系统的临界普适行为的验证。

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。