弹性波

In this paper an algorithm of finite element modelling is discussed for elastic wave propagating in two dimensional media. Two analytical formulas of the initial motion and wave form of P wave are derived in time domain for a point force source directing vertically down as a function of time with a bell shape.

本文讨论了二维介质中弹性波有限元模拟的一种方法；导出了二维无界空间中集中力点源的理论初动表达式和位移波形表达式，并和相似情况下的有限元结果进行了比较；对用有限元方法算得的几个中小模型的节点位移进行了分析。

Two dominate variation trends are distinguished in the data plots of compressional-wave velocity versus Possion ratio, indicating the effects of mud content and calcite cement on the elastic properties of sandstone samples. In each change trend, with the rock texture transfering gradually from grain-supporting to matrix-supporting with increasing mud and calcite cement content, the propagation of elastic wave also changed from grain-to-grain contacts to rock matrix, which resulted in the measured data illustrating extremely different tendency. It helps utilize the physics properties of reservoir sandstone to extract rock texture and diagenesis properties in the research area.

样品在纵波速度－泊松比交汇图中表现出两种主要变化趋势，分别对应泥质与钙质胶结物的影响；在每个变化趋势中随泥质含量与钙质胶结物含量的增加，岩石结构从颗粒所构成的骨架支撑逐渐表现为基质支撑，弹性波能量的传播也从通过颗粒接触边界转变为通过岩石基质传播，这是使砂岩样品测试结果表现出两种截然不同变化趋势的主要原因，为利用岩石物理特性从地震资料中提取岩石结构、沉积与成岩特征的信息提供了依据。

In this paper, the elastic wave propagation in a two-dimensional piezoelectric phononic crystal is studied by considering the mechanic–electric coupling.

本文考虑力电耦合效应，研究了弹性波在二维压电声子晶体中的传播特性。

Meanwhile, the localization factors in tuned and mistuned periodic ribstiffened plates are respectively computed and the effect of the degree of disorder of span-length and the structural parameters of the rib on the localization of elastic waves is analyzed and discussed.

同时，计算了谐和与失谐周期肋板结构中的局部化因子，并分析讨论了跨长的失谐程度以及加强肋的结构参数对弹性波局部化的影响。

Phonon crystal is a type of functional materials, which has the elastic band gap.

声子晶体是一种具有弹性波禁带的周期性结构功能材料。

The results of Glass tank test experimental showed that there is no viscosity change in stimulation of acoustic wave on test of TCE.

音波刺激玻璃槽实验结果发现，音波刺激对纯TCE的黏滞度并无显著的影响，但对孔隙介质中之纯TCE则有较显著的影响，因此推论单纯音波能量不足以改变TCE的黏滞度，而孔隙介质中TCE黏滞度的变化，应致因於音波使介质颗粒间摩擦而导致TCE黏滞度的变化，此实验结果可对弹性波增加污染物移除效果之机制，提供一项有力证明。

By using dynamics analysis software RecurDyn to establish a model for the prototype of a belt conveyor, this essay reaches through simulation research the conclusion that during the initial startup phase, it is necessary to maintain a lag between the speed of the tail pulley and that of the head pulley, mainly because it takes a certain amount of time for the elastic wave to travel through the belt to reach the tail of the conveyor.

应用动力学分析软件RecurDyn建立了带式输送机的样机模型，通过仿真研究，得出在起动初始阶段，尾部滚筒速度要滞后于头部滚筒速度一定时间，这主要是由于弹性波在输送带中进行传播到达尾部需要一定的时间；并且在起动阶段，输送带的张力比稳定运行时变化大，起动时间越长，输送带出现的最大张力越小。

In the light of the relation between rock velocities and confining pressure and pore pressure, the concept and formula of effective pressure is cleared in this thesis.

本文针对岩石的弹性波速度与围限压力和孔隙压力的关系，澄清了有效压力的概念和计算公式。

Because the underground reservoir rock is under high pressure and high temprature, it is very important to determine the relation between rock velocities and various pressures.

油气储层岩石在地下都处于高温和高压的环境，研究弹性波速度和各种压力的关系是岩石物性研究的重要内容。

The numerical results show that the simulation accuracy and efficiency are raised effectively by removing oversampling both in space and time domain.

一系列数值试验表明，该方法能够在保证模拟精度的同时，通过有效降低空间与时间维度上的过采样来显著提高弹性波模拟的效率。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。