查询词典 calculus of finite difference

This paper establishes the model of OCS according to the cable structure and creates nonlinear equation of finite elements method and solves the problem of the counts of drop length.This paper indicates that nonlinear method of finite elements is one of powerful tools of OCS analysis.

本文算例表明，非线性有限元方法是对接触悬挂进行分析的有力工具，只要建立接触悬挂的刚度矩阵和质量矩阵，就可以对接触网的吊弦长度进行准确的计算，这是传统的计算方法难以做到的。

In consideration of these complicated factors, Duncan—Chang model is used for the soil in this paper, and the deep excavation is modeled by using the method of coupling of multiple finite elements such that calculation results approach to actual condition. In addition, based on the theory of increment method, dynamic simulation using the finite element methods is investigated for the deep excavation.

考虑到众多复杂因素的影响，本文采用邓肯—张模型做为土的本构模型，使用该模型进行计算能够较为充分地考虑到各种复杂因素的影响，而且实际工程中对于邓肯—张模型的参数变化情况已积累了较丰富的经验：采用多种形式有限元耦合的方法对深基坑问题进行建模，从而达到使计算结果接近实际的目的。

To establish the constitutive equation of material, the metric tensor for stress , strain and their transformation equations between different configurations are derived, and basic theory of finite deformation as well as elasto-plastic deformation criterion are studied. By analyzing the applicability of different element models, four-node quadrilateral degenerated Mindlin isoparametric element is adopted because of its good versatility, and the element stiffness matrix is derived. The static implicit elasto-plastic finite element equation for complex skin stretch-forming is put forward based on Updated Langrange formulation.

本文首先系统地阐述了有限变形的相关基本理论，针对板料成形建立了应力应变度量张量及其相应的转换关系；介绍了材料的屈服准则、塑性变形强化规律、塑性流动规律以及加、卸载准则，并在此基础上建立了有限变形各向异性弹塑性本构方程；对板料成形的单元模型进行了分析，针对飞机蒙皮零件特点，采用通用性强的四节点四边形退化Mindlin等参壳单元进行成形模拟，并导出其单元刚度矩阵的具体形式；基于以上研究，以逐级更新Langrange描述的持续虚功率原理为基础，建立了率形式的复杂蒙皮拉形过程静态隐式弹塑性有限元方程。

Firstly, the 3D solid model of the analyzed object is built directly in the FEM software ANSYS 8.0 without using other CAD software. The influence of the side sizes of solid elements on computing results and the influence of coupling ways between different parts on the modal parameters are researched by simply modeling. And a new connecting method about joints in ANSYS is proposed and applied to finite element modeling of the test-bed for spindle system. Furthermore, several different computing techniques for modal parameters extraction are compared in solving the finite element model of spindle system test-bed. Many modal solutions are also done to achieve the relationships between the whole or part stiffness value and computed modal parameters. The laws about joint rigid parameters" influences on modal parameters are discussed by means of altering their values for conjoint parts. And by changing local rigid parameter values, the different location selections" influence on computed modal parameters is also studied.

本文通过使用ANSYS 8.0软件直接建立研究对象的实体结构模型，而没有借助其他的CAD软件；通过构建简单的模型研究实体单元边长大小对计算结果的影响，部件之间不同的联结方式对模态参数的影响，探讨在ANSYS中实现结合部的方法，提出一种新的联结方法，并建立主轴系统试验台的有限元模型；对建立的主轴系统试验台有限元模型求解，比较几种不同模态提取方法；通过改变结合部联结单元的刚度参数进行的计算，寻找联结刚度对模态参数变化的影响规律；改变局部联结单元的刚度参数，研究刚度值位置差异对计算模态参数的影响。

Oil film forces and its Jacobian matrix at any moment of sliding bearing with finite length is determined using finite element method based on the variational inequalities principle.

根据不等式变分原理，采用有限元离散化方法，求解有限长径向滑动轴承任一时刻的油膜力及相应的Jacobi矩阵。

Three moment method,the transition matrix method and finite element method in shipping shaft system alignment are used ,the application of finite element method in shipping shaft system alignment is proved to be more reasonable through an example .

并以某实船为例，利用三弯距法、迁移矩阵法和有限元法对船舶轴系进行校中计算，说明有限元法更先进合理。

The unbalance forces due to the lumped eccentric mass are treated as general forces. Meanwhile, the potential energy expression about gravity based on finite element method is presented for convenience. Based on the variational inequalities principle, the finite element is used to determine the film forces produced by fluid film bearing and damper at any moment and its Jacobian matrix with respect to location and velocity of journal and bearing house.

在第二部分中，主要应用有限元方法及Hamilton原理对所研究系统进行了建模分析，着重对质量偏心问题进行了分析处理，并对此提出了两种处理方法：一、转化为对系统动能的影响；二、将其产生的离心惯性力视为非保守的广义力，并对其表达式进行了推导，同时为分析问题方便，基于有限元离散化方法，推导了重力的势能表达式。

The fluid film bearing-flexible rotor nonlinear system with squeeze film damper is modeled practically using the finite element method and the Hamilton principle.(3) The film forces produced by fluid film bearing and squeeze film damper are determined by finite element method at any moment, and the Jacobian matrix is also determined.(4) A method for analyzing the dynamics of a large system with local nonlinearities is presented. The stability and bifurcation of the equilibrium position and the unbalance responce of a fluid film bearing-flexible rotor system with squeeze film damper are investigated based on the assumption of an incompressible lubricant together with the long bearing approximation for fluid film bearing, short bearing approximation for squeeze film damper and the"π"film cavitation model.

主要研究内容包括下面几个方面：（1）对挤压油膜阻尼器-滑动轴承-转子非线性动力系统中的非线性现象进行了机理方面的研究；（2）应用有限元方法及Hamilton原理对复杂的挤压油膜阻尼器-滑动轴承-转子非线性动力系统进行了建模分析；（3）对滑动轴承及挤压油膜阻尼器中任一时刻的油膜力及相应的Ja-cobi矩阵的确定进行了分析；（4）对一类具有局部非线性的多自由度动力系统，提出了一种可以有效地分析其动力特性的方法；（5）采用实验与理论分析相结合的方法，对挤压油膜阻尼器-滑动轴承-转子非线性动力系统的动力特性进行了分析。

The theoretic and finite element analysis of monition explode in concrete are got.The principle of ammunition explode or shock bridge and finite thickness dynamic deform are analyzed by the blunt bullet strike the bridge.

分析了弹丸冲击桥梁的动态响应，用有限元方法对钝头弹冲击梁的过程进行了仿真，得到了梁的破坏过程，梁的应变云图，测点的速度、加速度和位移响应。

Although the quantum double of a finite Clifford monoid is indeed a generalization of the quantum double of a finite group, the quantum doubles in [L2] can not usually be regarded as

作为特殊情况，非交换的半格分次弱Hopf代数的量子偶同样可以构造出来。作为群和非交换非余交换Hopf代数的量子偶的构

You can snipe the second and third union leaders from this position.

您可以鹬第二和第三工会领袖从这一立场出发。

Aiming at the currently shortage of XML streams quality detecting, this paper proposes a new forecasting method of XML streams quality by least squares support vector machines, which is used the method of XML keys' vector matrix as windows, and vector product wavelet transform to multilevel decompose and refactor the XML streams series, that can fulfill real-time checking demand of XML quality, and ensure constraint, consist- ency and integrality. For even more adapting net load, it proposes a control strategy by weight and adaptive adjustment to ensure XML streams quality.

针对当前XML数据流质量检测存在的不足，提出构建XML键的矢量矩阵作为窗口，利用矢量积小波变换多级分解与重构XML数据流，再结合最小二乘支持向量机对XML数据流质量进行预测的一种方法，满足XML数据流质量重构时实时检测的要求，保证XML数据的约束性、一致性与完整性；为了更好的适应网络负载，采取加权与自适应窗口调整等调度策略充分保证XML数据流的质量检测。