数值方程

In most situations, the polysome system dynamic equation is the non-linearity the ordinary differential equation or the differential - algebra system of equations, it is generally obtains the equation through the computer value simulation then get the numerical solution, then through to numerical solution analysis, understanding polysome system dynamics characteristic.

多数情况下，多体系统的动力学方程是非线性常微分方程或微分-代数方程组，一般是通过计算机数值仿真得到方程的数值解，然后通过对数值解的分析，了解多体系统的动力学特性。

In the numericalstudy, three-dimensional elastodynamics equations and Morison equation are applied tosimulate the time histories of dynamic response of submarine pipelines suspended over flatbeds sucessfully. The three-dimensional interaction of pipeline and internal flow isnumerically simulated by applying the iterative computation to the fluid-structure interfacesand using the elastodynamic equation and the incompressible fluid N-S equation andcontinuity equation.

在数值研究方面，本文利用三维弹性动力学方程，结合莫里森方程，较好地模拟了规则波浪作用下近壁悬跨弹性海底管线动力响应过程，结合不可压缩流体N-S方程和连续方程，进行管线及其内部流体的三维流固耦合数值计算，基于数值计算结果探讨内流管线系统的动力特性和管内流体特征。

Using Biot's 2D elastodynamic theory solves the saturated soil equation. The Fredholm integral equation of the second kind can be built by using the fundamental solution of circular load, the compatibility condition and superposition method. The Fredholm integral equation of the second kind of pile groups can be solved by using numerical method. The numerical solutions of pile groups axial forces, pore pressures under vertical harmonic loading and shear forces, moments and pore pressures under horizontal harmonic loading can be obtained.

采用Biot提出的三维波动原理，利用圆形简谐载荷作用下的Biot固结方程的基本解和桩土之间的变形协调条件，并采用叠加原理得到饱和土中群桩的第二类Fredholm积分方程，应用数值法求解群桩的第二类Fredholm积分方程，得到在垂直简谐载荷作用下群桩的轴力、孔压随桩身变化的数值结果以及在水平简谐载荷作用下群桩的剪力、弯矩和孔压随桩身变化的数值结果。

Random measured data is regressed using SPSS software,and the mathematical model among internal returns ratio and the daily production of single well and the well depth was obtained.

利用SPSS软件对随机测得的数据进行回归，得到内部收益率与单井日产量和井深的具体数值方程。

Establish the steady-state and transient model using the three hydrodynamics equations (Continuity equation, Momentum equation and Energy equation). By comparing different state equation, it selects the BWRS state equation which is considered the most accurate state equation in current natural gas measurement. It calculates compression factor, density and other Thermal parameters based on BWRS state equation. In Numerical solution of the steady-state and transient model, compression factor, friction coefficient and all the other Thermal parameters are recalculated in each small time step to reduce the numerical calculation error.

在稳态模型的建立上，利用流体力学三大方程(连续性方程、运动方程和能量方程)，通过比较不同的状态方程选用了目前被认为最精确的用于天然气计量的BWRS状态方程，并以此方程为基础进行压缩因子、密度等热物性参数的计算；在稳态模型的求解上，选用容易计算，精度较高的标准型龙格—库塔(Runge-Kutta)法进行数值求解，并且在迭代过程的每一小步都重新计算燃气的压缩因子，摩阻系数等所有的计算参数，以减少数值计算的误差。

It separates the network into symmetrical parts and unsymmetrical parts,synthetically uses sequence compo nents an d phase components.In the sequence domain,it equals the symmetrical parts to its boundary nod es;in the phase domain,with the po lym orphic calculationtechnique,it deals wi th all kinds of faults directly without huge calculating work as it is in the conventional phase compo nents methood.The example shows the advantages of this improved method.

该方法以相分量故障处理方法为依据，在序坐标下化简对称部分，等效到其边界节点，在相坐标下对化简后的网络处理各种简单和复杂故障，采用多态计算技术，以矩阵变换代替传统的数值方程的计算，避免了相分量法计算量大的缺点。

Based on modern optimization theory and optimal control theory, this dissertation studies some questions as follows:1. The optimization model of parameter identification of three-dimensional geologic history numerical simulation, algorithm and its applicationGeologic history numerical simulation is a basic content of basin numerical simulation, and the porosity is the major parameter in the evolution and development process of oil-bearing basin. According to the sedimentation and burial mechanism, the physical and chemical principles of oil geology, the mudstone porositys non-linear parabolic partial differential equation has been established.

本文应用现代最优化及最优控制理论，对如下一些问题进行了研究： 1、三维地史数值模拟的参数辨识优化模型、算法及应用地史模拟是盆地数值模拟的一个基础性的研究内容，地层孔隙度是含油气盆地地史演化发育过程中的重要参数，根据地层沉积埋藏机理和石油地质的物理化学原理，通过引入数学物理方程概念，建立了泥岩三维孔隙度场方程，根据问题的特点，给出了方程的定解条件，对方程的动边界也给出了处理方法，并且证明了解的存在性与惟一性，在此基础上建立了以当今实测数据为拟合准则的三维地史数值模拟的参数辨识优化模型，这是一个含有二阶偏微分方程约束的泛函极值问题。

In this topic, the dynamic analysis methods for piezoelectric vibrator are studied systematically based on the theoretical model, FEM numerical experimentation and FEM governing equation for given compound-mode vibrator, and some valuable conclusions are obtained. The main work accomplished is summarized as follows: 1.Elaborate the main modeling methods for piezoelectric vibrator and the significance and necessity to study the dynamic characteristics of piezoelectric vibrator which emphasize the urgency of this paper. 2.Take the bending deformation induced by piezoelectric ceramic as example, the energy transfer mechanism of electric energy to mechanical energy are analyzed; the motion and force transfer mechanism are analyzed for the longitudinal-bending vibrator. 3.Based on mode assumption and Hamilton principle, the coupling model of piezoelectric vibrator of linear USM is built; moreover, the equivalent circuit model is obtained and a coupling equation represents the relation between electric parameters and mechanical parameters is derived which provides foundation to match the vibrator and driving circuit. 4.Combine the constitutive equation of piezoelectric ceramic with elastic-dynamical equation, geometric equation in force field and the Maxwell equation in electric field and the corresponding boundary condition equation, the FEM control equation for piezoelectric vibrator of USM to solve dynamic electro-mechanical coupling field is established by employing the principle of virtual displacement. The equation lays the foundation to study the non-linear constitutive equation of piezoelectric ceramic driven by high-power. 5.Define the dynamic indexes of characteristic of vibrator and carry out variable parameters simulation by calculating the model parameters and the electric characteristics of vibrator are simulated according to the equivalent circuit model. By numerical experimentation, the working mode of vibration of vibrator and the shock excitation results of the working frequency band which provides the mode frequency to realize bimodal are analyzed. Detailed calculation of the electro-mechanical coupling field parameters is made by programming the FEM control equation.

本课题从理论模型、有限元数值试验、有限元控制模型等方面以复合振动模式振子为例对超声电机压电振子的动力学特性及其分析方法进行了全面系统地研究，得出了许多有价值的结论，主要概括如下： 1、阐述了目前针对超声电机压电振子的主要建模方法，对压电振子动态特性的研究意义和必要性进行了论述，突出了本文研究内容的迫切性； 2、以压电陶瓷诱发弹性体发生弯曲变形为例，分析了压电陶瓷通过诱发应变来实现机电能量转换的机理；对基于纵弯模式的压电振子的运动及动力传递机理进行了分析； 3、基于模态假定，利用分析动力学的Hamilton原理，建立了面向直线超声电机压电振子的机电耦合动力学模型，并据此建立了压电振子的等效电路模型，导出了电参量与动力学特性参量的耦合方程，为压电振子与驱动电路的匹配提供了依据； 4、从压电陶瓷的本构方程出发，综合力场的弹性动力学方程、几何方程、电场的麦克斯韦方程以及相应的边界条件方程，采用虚位移原理，建立了压电振子动态问题机电耦合场求解的有限元控制方程，为研究其大功率驱动下的非线性本构模型奠定了基础； 5、界定压电振子的动力学特性指标，对压电振子的机电耦合动力学模型参数进行计算及变参数仿真；依据等效电路模型，对压电振子的电学特性进行了仿真分析；通过有限元数值实验，对压电振子工作模态附近的模态振型及工作频率附近的频段进行了激振效果分析，找出了实现模态简并的激振频率；利用有限元控制方程，通过编程计算，对压电振子的力电耦合场参数进行了详细计算，得出了一些有价值的结论。

In the couping solution, based on the characteristics of the models in this dissertation, each of loading step is finished in unit time. Thus the volumetric strains on the current increment step as analysis parameters are inserted into the equation of continuity and a physical equation for pore water pressure is presented. The fundamental solutions of two kinds of classic problems (axial symmetry and plane strain) are derived. By use of the fundamental solutions of pore water pressure combined with finite element method of soil mechanics, a semi-analytical and semi-numerical method for nonlinear consolidation equations is presented.

在耦合分析中，根据本文模型的特点，将每一荷载增量步看作单位时间完成，对应当前增量步的体变分量作为分析参数代入连续方程，建立了基于数值模型的孔压变化方程，根据工程中最常见的两类问题推导出基本解，结合土骨架的控制方程建立了此类液-固耦合问题的半解析半数值解答体系，编制了有限元程序，从而实现了从建立本构关系到模拟固结问题的全数值方法。

A three dimensional Navier Stokes equation is solved with a standard k ε turbulent model. Two experiments were carried out and the total pressure of jet flow was tested. Based on the tests, the differences between the calculated and test results were found to be 3% and 7% respectively. It proved that the results of calculation can well be used in engin...

研究采用数值计算和试验测量相结合的方法，控制方程为三维、雷诺平均 Navier- Stokes方程及 k-ε二方程的紊流模型，并且对该发动机进行了燃气流场的测试，对流场中的总压强进行了直接测量，进行了两次试验；在两次测点位置，试验结果与数值计算值相差分别为 3%和 7%；证明了对双喷管火箭燃气射流流场的数值计算具有了较好的精度，计算模拟结果可以用于工程设计中

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。