波导

In this dissertation, the propagation of axial symmetric longitudinal wave mode under the complicated stress environment is investigated.

由于轴对称纵向模式的导波的激发和接收比较容易，且它的各种特性与板中Lamb波很类似，因此轴对称纵向模式成为了工程中利用导波进行无损检测时采用最多的一种模式，所以本文对该种模式在复杂应力环境下管壁中传播特性进行了深入的研究。

And by applying the linear dispersion relation of wave, all the properties of wave refraction including wave rays, constant phase lines, phase function and crest lines etc., can be expressed in explicit functions. By introducing an orthogonal curvilinear coordinate along the wave ray and the constant phase line, and with an estimated scale factor, the refraction coefficients along any wave ray can then be determined. The present results are verified by ordinary wave ray theory and some previous numerical results.

就此特例情况在波浪的线性分散关係的应用下，前进波浪折射现象的整体特性，包括波向线、等位相线、位相函数与波峰线皆被导述出明確显然的函数表示；同时引入由沿著波向线与等位相线所构成的完全符合波浪折射几何通性的正交曲线座標，求出其尺度因子后，由能通量守衡原则定出沿著任一条波向线上的折射係数；並由之对往昔纯依两相邻的波向线间的几何类比所给定的折射係数给予导証之。

Using the finitedifference timedomain electromagnetic method and c language program in the matlab software,the spatial electromagnetic field distribution radiation of photoconductive dipole antenna is calculated and displayed on the computer in a pseudocolor graph.

研究了光电导天线产生太赫兹波的辐射特性，利用麦克斯韦方程及其边界条件，计算了近远场的电场强度；采用电磁波时域有限差分方法，在Matlab系统软件中，用C语言编写程序计算光电导偶极天线的辐射太赫兹波的空间电磁场分布，并在计算机上以伪彩色图形显示，这种电磁场的可视化结果为天线的设计和改进提供了直观的物理依据。

Making use of field matching method,combining with the variational method,the dispersion equation of the ridge loaded ring plane slow wave structure and small signal gain of this type of TWT are presented in this paper.

脊加载环板行波管是一种频带相对较宽的大功率行波管，本文用场匹配和变分原理相结合的方法，研究了脊加载环板慢波结构的导波特性及这种行波管的小信号、大信号特性，讨论了结构的几何尺寸及电子注参量对慢波的传播特性、小信号增益及注波互作用非线性效应的影响。

The multipath effect is an avoidless problem which the tracking radar and the searching radar among CIWS has to face. This paper analyses the form of the multipath effect on geometry, emphasizes the distance difference between the direct wave and the reflected wave, according to this inherent characteristic, the paper introduces the theory of HRR to the design of radars among CIWS, discusses the spike pulse technology and ultra wide hand technology which often be used, finally proposes the method of time-frequency code to obtain the high range resolution and avoid the multipath effect.

多路径效应是近程反导武器系统中的搜索雷达和跟踪雷达均无法避免的问题，文中分析了多路径效应形成的几何原理，并根据多路径效应中的直射波与反射波具有路程差的固有特性，将高距离分辨率雷达信号理论引入到近程反导武器系统的雷达中，讨论了实现高距离分辨率的窄脉冲和超宽带技术，最后提出了目前较易实现的时间－频率码合成高距离分辨率的办法。

Following, a experiment has been carried out, the incident waves with a frequency band of 200kHz-3 50kHz are used to the experiment, and a series of peak value-time curves are drawn each 10kHz, corresponding time are found through fitting peak value, thus the position of the defect is calculated accurately. The application of awl-shaped sensor head in the heat change water pipe experiment indicates that the ultrasonic guided waves may transmit nearly 50 meters in the pipe, which is not influenced by the elbows and makes it possible to test defects in long distance and large-scale. The water-load pipe experiment indicates that the displace and energy maybe leakage at the near-surface, which is significant for the further research.

而后，采用200kHz至350kHz频段的入射波进行了实验验证，并每隔10kHz绘出一条峰值一时间的曲线，通过拟合峰值点，找到对应的时间，从而准确的计算出了缺陷的所在；应用锥形探头的热交换水管的实验表明，超声导波可以在管道中传播了近50米的距离，且不受弯头的影响，从而使得长范围、大规模检测成为可能，水载管实验说明了离面位移和能量可能会发生泄漏的特性，为导波的深入研究和应用作了铺垫。

The three-dimensional finite element model of guided wave in the pipe was built by the finite element method.

利用有限元方法建立管道导波3-D模型，通过在管道中激励纵向超声波，模拟导波在管道中的传播形态。

According to the guided wave technique, the displacement of guided wave propagation at an arbitrary time and point on the surface of a pipe is described.

在导波传播理论和频散波形预测理论的基础上，研究了超声导波在检测管道时，如何利用时域波形重构缺陷图像的问题。

Emphasis is given to the ultrasonic guided wave technology and modal acoustic emission technology, including the propagation characteristic of guided waves, the method of experiment and numerical simulation etc.

着重对超声导波技术和模态声发射技术在管道检测中的最新应用进行了评述，内容涉及超声导波的传播特性、实验检测方法及其数值模拟等。

The mode simulated the propagation of guided wave in a pipe by applying the longitudinal ultrasonic to the pipe end.

利用有限元方法建立管道导波3-D模型，通过在管道中激励纵向超声波，模拟导波在管道中的传播形态。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。