数值算法

Numerical algorithm and symbolic algorithm arethe fundamental approaches for this problem.

数值算法和符号算法是两类求解多项式优化问题的方法。

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。

With the application of the sampling theorem and the Fast Fourier Transform, two groups of numerical forms of the algorithm equations suitable for two kinds of FFT subroutines are derived. Finally, the measurement algorithm is fully tested by the measurement and calculation carrier out for an MMW irradiator.

在解析算法的基础上，应用采样定理和快速傅里叶变换，推导了分别适用于两种快速傅里叶变换子程序的数值算法公式，通过对一种毫米波辐射器的实际测量和计算对测量算法进行了整体检验。

The main achievements of this dissertation are as follows: Let W be a nonsingular matrix. 1. Problem I and Problem II are considered under the matrix set S is as the following: 1 the set of real W-symmetrizable matrices; 2 the set of real W-symmetrizable nonnegative definite matrices; 3 the set of real W-symmetrizable matrices on the linear manifold.

对于问题I和问题II，本文就S是W可对称化矩阵集合、W可对称非负定化矩阵集合以及线性流形上W可对称化矩阵集合等三种情况进行了研究，分别给出了这三种情况下问题I的解存在的充分必要条件，以及解集合的通式表达式，给出了这三种情况下的最佳逼近解，并提供了相应的数值算法和数值实例。

This is a kind of nonlinear programming problem with complex structure, which is difficult to solve by traditional numerical algorithm.

这是一类结构复杂的规划问题，很难采用传统的数值算法进行求解，遗传算法提供了有效的解决方法。

The effect of the elastic-plastic matrix of friction soil with nonrelevant flow rule on the numerical convergence of finite element method is analyzed in this paper; and the effect of elastic modular, poisson ratio and earth pressure coefficient on numerical results are studied in this paper. At the same time, the hybrid element with a mixture of displacement and stress variables and the conventional element with solely displacement variable are compared when used in geomaterials.

在ABAQUS有限元分析软件的基础上，本文研究了服从非关联流动法则摩擦性土体的弹塑性矩阵对有限元数值算法的影响，并研究了弹性模量、泊松比以及地基土压、力系数对数值计算结果的影响，同时探讨了数值分析过程中常规位移元与杂交元在岩土工程中的应用。

In this paper,the scheme of autonomous orbit determination of satellite is described,the extended Kalman filter algorithm based on improved numerical method is put forward.

高精度的自主定轨对探测器实现深空探测任务有着重要的意义，结合利用星光折射角的测量确定卫星轨道的自主导航方案，提出了基于数值算法改进的扩展卡尔曼滤波算法，提高了运算精度，通过仿真验证了该算法的优越性。

The Jacobi matrix rank one update problems, given either their mix-type eigenpairs or their pricinpal submatrix and defective eigenpairs(the eigenvalues of the matrix and some elements of the corresponding eigenvectors) are also discussed.

n阶对称箭形矩阵与n阶Jacobi矩阵一样只有2n-1个非零元素，类似Jacobi矩阵逆特征值问题的提法，本文提出并讨论了六类对称箭形矩阵逆特征值问题，研究了这类矩阵的结构性质，得到了问题有解的充分必要条件及求解的数值算法和数值算例。

It is proved that equilibrium solutions of this differential system are solutions to the complementarity problem and a numerical algorithm is given based on the numerical integration of the system of ordinary differential equations.

在一定条件下，证明了微分方程系统的平衡点是非线性互补问题的解并且基于一般微分方程系统的数值积分建立了一个数值算法。

The results of numerical analysis show that the elastic modular and the poisson ratio have no effect on two-dimensional bearing capacity, but can affect the ultimate bearing capacity of three-dimensional foundations and control the convergence and precision of finite element calculation; the earth pressure coefficient controls the geostatic stress of foundation, sequentially affects the ultimate bearing capacity of foundations and the convergence of numerical calculation. When calculating the ultimate bearing capacity of undrained saturated foundation, the complete formulation exists shear locking, and reduce formulation exists hourglassing, so the hybrid formulation is suitable to imitate the geomaterial. When the soil obeys nonrelevent flow rule, the yielding function is different from potential function, and the elastic-plastic matrix of soil is asymmetric, so the unsymmetry numerical solver and appropriate finite element mesh is required.

研究结果表明，土体弹性模量和泊松比对二维基础极限承载力没有影响，但是影响着三维矩形基础的极限承载力，控制着ABAQUS数值算法的计算精度与收敛速度；地基土压力系数控制着地基土体中的地应力平衡，从而影响着二维条形基础和三维矩形基础的极限承载力和地基破坏包络面；对于不排水饱和软黏土地基，常规的完全积分单元会造成剪力自锁现象，而减缩积分单元则存在过于柔化的现象，故采用杂交单元来模拟较合适；当土体服从非关联流动法则时，屈服函数与塑性势函数之间存在差异，从而导致土体弹塑性矩阵呈现非对称性，在有限元计算中必须采用非对称数值解法，并且合理地划分单元才能对极限承载力进行准确求解。

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。