结构方程

In the end, the main content of this dissertation is addressed.In chapter 2, based on the analysis of present vibrators principle and structure, two kinds of transfer functions and frequency response curves of the vibrator, driven by voltage feedback power amplifier and current feedback amplifier, are given separately. And turnover frequencies between different frequency rangs are also given.

第二章分析了标准振动台的工作原理和结构，在此基础上，建立了标准振动台的机械和电气方程，给出了恒压源和恒流源功放激励下的振动台传递函数及幅频、相频特性曲线，列出了不同频段间的转折频率。

The finite element motion equation of the damped blades is obtained.

接着建立了叶片型线部分有限元模型，阻尼结构的有限元模型，阻尼连接单元的有限元模型，在此基础上建立了阻尼叶片的有限元运动方程。

Differential equations of tile first order in the finite discrete function are established, the solutions of which have very simpler structure.

引入了有限离散函数的微分与积分新概念，它具有与连续函数微分和积分相类似的性质，由它建立的一阶微分方程的解有较简单的代数结构。

For the reliability analysis of implicit limit state function, finite element analysis is a time-consuming process, and it impedes the application of normal importance sampling approach.

对于含有隐式极限状态方程的问题，重要抽样方法将大部分的计算时间用于结构有限元分析，这使得重要抽样的计算效率被大大降低了。

In this paper, we consider hyperbolic conservation laws, and the following work has been done to the finite volume method on unstructured meshes :In preface , we introduce the backupground of the oringe of the finite volume method, and point out the limitation of the finite difference methods and the finite element methods, and import the finite volume method.

本文主要考虑双曲型守恒律方程，对二维非结构三角形网格有限体积方法作了如下工作：介绍了有限体积方法的产生背景，指出了有限差分方法和有限元方法中的特点，对有限体积方法的产生和发展给出了比较详细的分析。

Studied present measuring methods" advantages and disadvantages, and presented the necessity and importance of researching propellant transient heat transfer.2.according to 130 and aeronautic 90 rocket projectiles" structure, analysed and acquired physical and mathematical models for propellant transient heat transfer, also designed propellant temperature field simulation units for test.3.acquired discrete transient heat balance equation and temperature calculation program, and gave contrasting curves between experimental temperature values and program calculating temperature values as well as maximum errors and average square root errors between them.4.by programs based on the first class boundary condition, worked out temperature distribution in propellant temperature field simulation units at different time, analysed temperature field distribution law and main elements affecting heat transfer, acquired propellant mass weighted average temperature and one at the half position of propellant maximum thickness as well as maximum errors and average square root errors between them.5.established transient heat transfer mathematical model and temperature calculation program for the third class boundary condition, drew contrasting curves between temperature experimental values and calculation values and gave maximum errors and average square root errors between them, got temperature distribution in the simulation unit at different time and main elements affecting heat conduction, figured out propellant mass weighted average temperature and one at the half position of propellant maximum thickness as well as maximum errors and average square root errors between them.

分析了现有测试方法的优缺点，提出了研究推进剂瞬态导热的必要性和重要性。 2。根据130和航90两种火箭弹的结构，分析得到了推进剂传热的物理模型和数学模型，设计了推进剂温度场模拟实验装置。 3。得到了离散形式的瞬态热平衡方程和温度场计算程序，给出了实验温度与程序计算温度值的对比曲线及其最大偏差与均方差。 4。利用程序求出了第一类边界条件下、不同时刻推进剂温度场模拟装置中的温度分布，分析了温度场的分布规律和影响传热的主要因素，求出了推进剂质量加权平均温度和最大肉厚1／2处的温度时间曲线并给出了两者之间的最大偏差与均方差。 5。建立了第三类边界条件下的瞬态导热数学模型和温度计算程序，求出了温度实测值与计算值的对比曲线并给出了两者之间的最大偏差与均方差，得到了不同时刻温度场模拟装置的温度分布与影响导热的主要因素，求出了推进剂质量加权平均温度和最大肉厚1／2处温度及两者之间的最大偏差与均方差，讨论并确定了能代表130和航90推进剂温度的特征点的位置。

At first, basing on the boundary value problem concerned with fluid-composite structure interaction and characteristic of acoustic wave radiation, a generalized Hamilton variational principle is derived, and the equations of motion based on the finite element method is also derived.

首先，从复合结构与流体相互作用问题的有关混合边值问题出发，针对声波辐射特点，推导了一种广义形式的Hamilton原理及有限元形式的运动方程。

In this article two functional modes of the Fly-back Converter (Continuous Conduct Mode and Discontinuous Conduct Mode) are particularly analyzed, which include their characteristics, applications, the critical pattern of two functional modes is argued, both the exact boundary from the angle of circuit parameters is crystallized, at the same time, basic principle of PFC under the DCM mode is introduced, which settle theoretical basis for the subsequent design; by establishing the mathematic model of the converter, a further investigation of the configuration is made, qualitatively and quantitatively, analyzed to settle exactly theoretical basis for the subsequent emulation and the experimental parameter; from the angle of steady-state analysis, the transfer function of the system is deduced to establish dynamic small-signal state equation, emulating the system with the help of matlab, then according to the simulation result and the theory of PFC revise the system, lastly, we adopt the project which add a zero-pole compensator to the voltage loop, by this way, a satisfied system performance is gained and the PFC scheme is ensured successfully; finally, based on the previously-done work, we combining with the situation of specific design requirement, acquired the numerical value of each unit devices in this converter

详细分析了反激式变换器的两种工作状态，连续模式(Continuous Conduct Mode ，简称CCM)和断续模式(Discontinuous Conduct Mode，简称DCM)以及各自的特点、应用场合，论证了两种工作状态的临界模式，从电路参数的角度明确了二者的界限，同时还介绍了DCM模式下PFC的基本原理，为后面的设计奠定理论基础；通过对整个变换器系统建立准确的数学模型，对此变换器的电路结构做了进一步的研究，定性、定量地分析了变换器各部分的工作状态，为仿真和实验参数的确定以及电路参数的优化提供理论依据；从稳态分析的角度，为系统建立了动态小信号状态方程并推导出系统的传递函数，利用matlab对系统进行仿真，进而根据仿真结果以及PFC的相关理论对系统进行校正，采用在电压环加入零点—极点补偿器的设计方案，得到了满意的系统特性并且保证了PFC的顺利实现；最后，在前面所做工作的基础上，结合设计要求计算出此变换器系统中每个元器件的数值，利用Pspice对其进行了仿真、优化，然后根据仿真结果搭建了硬件电路。

Using the theory of radiation modes and the piezoelectric equation, a Fourier series expansion method is presented to design the PVDF sensors.

该文在声辐射模态理论及一维分布式压电传感器方程基础上，以Fourier级数展开的方法，给出了梁结构PVDF传感器形状与边界条件无关的设计方法。

In this paper,the three-dimensional structure of the large-scale interstellar gas under the action of the resultant gravitional field of stars and gas is discussed on the basis of the fundamental equations of gas dynamics.

本文从气体动力学的基本方程出发，讨论了在银河系的恒星和气体的总合引力场作用下，星际气体的大尺度三维结构。

In the negative and interrogative forms, of course, this is identical to the non-emphatic forms.

。但是，在否定句或疑问句里，这种带有"do"的方法表达的效果却没有什么强调的意思。

Go down on one's knees;kneel down

屈膝跪下。。。下跪祈祷