假定

How to easily and reasonably determine the value of principal stress in the direction of plane strain is the key point.

基于弹塑性理论及土的试验规律，在平面应变的简单加载条件下，假定主应力之间的关系为双线性函数，并利用一维固结和破坏时的主应力状态，确定双线性函数的系数，得到平面应变方向上主应力计算公式的一个较合理形式，为应力状态和材料性质的函数。

The principal stress in the plane strain direction, which can be determined under the rigidity-plasticity assumption using static earth pressure coefficient , is the intermediate principal stress under the limit equilibrium condition. The relationship between major and minor principal stresses is obtained based on the strength criterion.

平面应变方向上的主应力在极限平衡条件下为中主应力，在刚塑性假定的基础上通过静止土压力系数确定，结合强度准则得到大主应力与小主应力之间的关系，进而求得土压力系数。

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。

The result of probability distribution in the paper is consistent with outcome of Hypothesis test, so verify the assumption of PERT technology is objective.

本文求解出的概率分布结果与数理统计中假设检验的求证结果一致，从而验证了PERT技术的概率分布假定是符合客观实际的。

We are working on the assumption that it would cost 5,000 to administer his estate and to obtain probate.

我们正在假定要花5000英镑，并获得他的遗产管理认证。

The only assumption is that each patch of input surface model can be treated as a single-valued function by properly specifying the projection plane.

该方法仅假定表面模型的每个面片在取定适当的投影平面时可看成是一个单值函数。

Get the students to know what the functions of every relative pron are in the attributive clause.

假定你是李华，从小喜爱大熊猫，一直通过有关网站关注三年前在美国圣迭哥动物园出生的大熊猫"苏琳"和她的母亲"白云"。

Some have supposed that the name is simply a title descriptive of his character as a messenger of Jehovah, and not a proper name.

有些人假定的名称，简直是标题描述他的性格作为一个信使的耶和华，而不是一个适当的名称。

The four crew of the Prowler were killed, one body was found the other three missing presumed killed.

漫游者的四乘员组被杀害了，一个身体被发现了另一三错过被假定杀害。

Jeanette Zweifel - Psychosynthesis and its Application in our Lives (21MB zipped MP3s, duration: 46.22 minutes) Psychosynthesis is a theory of psychology, developed by Roberto Assagioli, positing that we each have a higher unconscious which is our connection to the spiritual.

珍妮疑-psychosynthesis及其应用在我们的生活(传送的MSMP3机，期限：46.22分钟)psychosynthesis是一种心理学理论，研制阿萨，假定说，我们每个人都应有更高昏迷，这是我们连的精神。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐