查询词典 wave propagation

This problem is also important and valuable in Nonlinear Optics. It will be very helpful to understand how the aberrations affect the course of three- wave mixing, such as the change of conversion efficiency, the distribution of intensity and phase.Small signal solution of aberrated second harmonic generation is deduced from three-dimension three wave coupling functions. The numerical work gives out lot of results of different aberrations. The effects of the fundamental waves aberrations, which will change the conversion efficiency, distribution of intensity and phase in the frequency conversion, is analyzed. It shows that when walk-off and diffraction effects could be ignored approximately estimation of the phase distribution of second-harmonic wave could be done. The far field divergent angle and second moment radius of harmonic wave will vary with the aberration of fundamental wave, but the far field divergent angle will be obviously smaller than that of fundamental wave. The phase distribution of both fundamental and harmonic wave is measured using Hartmann-Shack wave front sensor in the experiment with 1064nm and 790nm lasers, respectively. Results are given.

首次从三维三波相互作用方程组推导得到了位相畸变光束倍频的小信号解；通过建立国防科学技术人学研究生院学位论文三维数值模型，编写相应仿真程序，首次得到了位相畸变光束倍频过程的大量计算结果，深入细致地研究了位相畸变光束经非线性光学频率变换后谐波的转换效率、光强分布、位相分布以及影响它们的各种因素；得出谐波的远场发散角和光斑二阶矩的变化规律会因为基波像差的不同而不同，但谐波的远场发散角明显地比相应基波的小的结论；得到了在走离效应和衍射效应等影响许多因素可以忽略的情况下，位相畸变传递到二次谐波的估算式；举例分析了KDP三倍频方案中，基波位相畸变对二次谐波和三次谐波的影响；实验工作中，用哈特曼一夏克传感器分别对IO64nm倍频过程和790飞秒超短脉冲倍频过程中的基波和谐波的位相分布进行了测量，给出了相应结果。

Small signal solution of aberrated second harmonic generation is deduced from three-dimension three wave coupling functions. The numerical work gives out lot of results of different aberrations. The effects of the fundamental wave's aberrations, which will change the conversion efficiency, distribution of intensity and phase in the frequency conversion, is analyzed. It shows that when walk-off and diffraction effects could be ignored approximately estimation of the phase distribution of second-harmonic wave could be done. The far field divergent angle and second moment radius of harmonic wave will vary with the aberration of fundamental wave, but the far field divergent angle will be obviously smaller than that of fundamental wave. The phase distribution of both fundamental and harmonic wave is measured using Hartmann-Shack wave front sensor in the experiment with 1064nm and 790nm lasers, respectively. Results are given.

首次从三维三波相互作用方程组推导得到了位相畸变光束倍频的小信号解；通过建立三维数值模型，编写相应仿真程序，首次得到了位相畸变光束倍频过程的大量计算结果，深入细致地研究了位相畸变光束经非线性光学频率变换后谐波的转换效率、光强分布、位相分布以及影响它们的各种因素；得出谐波的远场发散角和光斑二阶矩的变化规律会因为基波像差的不同而不同，但谐波的远场发散角明显地比相应基波的小的结论；得到了在走离效应和衍射效应等影响许多因素可以忽略的情况下，位相畸变传递到二次谐波的估算式；举例分析了KDP三倍频方案中，基波位相畸变对二次谐波和三次谐波的影响；实验工作中，用哈特曼-夏克传感器分别对1064nm倍频过程和790飞秒超短脉冲倍频过程中的基波和谐波的位相分布进行了测量，给出了相应结果。

In section one, by using FICE scheme and TIME-GCM, a model of trace gases and OH airglow affected by gravity wave is set up, then the propagation of nonlinear gravity wave and the effect on trace gases and OH airglow are analyzed. The result shows gravity wave excited by tropospause forcing can propagate stably to the mesosphere through the stratosphere so that energy and momentum can be transferred from one region to another. In this process, gravity wave undergoes growth, overturning, convection and breaking. And the no-isothermal structure can accelerate the breaking of gravity wave in mesospause, and the breaking of gravity wave is an important source of convection and small-scale waves.

在第一部分的工作中，利用全隐欧拉格式和全球热层-电离层-中间层-电动力学环流耦合模式，对重力波的非线性传播及其在传播过程中对中高层大气中氧族和氢族成分和与之密切相关的OH气辉辐射的影响进行了数值模拟，结果表明，从对流层向上传播的重力波经历了产生、发展、饱和、对流产生直至破碎的非线性演化，大气的非等温结构加速了重力波在中层顶区的破碎，重力波的非线性传播是小尺度对流和湍流产生的一个重要的源。

Based on basic theory of elastic wave propagation, wave equation forpropagation of elastic wave in 2 dimension vertical inhomogeneous mediumof similar concrete cutoff wall model is developed. 2 dimension elastic sheetof concrete cutoff wall is established to research law and energy distributionrelations between propagation, attenuation, reflection and transmission ofelastic wave in concrete cutoff wall; Based on the concept of resolution, thecontent of vertical reflection method used to inspect concrete cutoff wallresolution is raised and factors will have influences on resolution are analyzed,expression of defective layer composite reflection factor and detectabledefective layer maximum thickness are developed; Relations between allsteps of sampling system of vertical reflection are build, the influence ofcentrum characteristics and receiving sensor on testing results are analyzed,therefore parameter requirements for testing instrument and parameter selection principle of collected parameters are raised.

2从弹性波传播的基本理论研究出发，推导了弹性波在类似混凝土防渗墙模型的二维垂向不均匀介质中传播的波动方程式；建立了混凝土防渗墙二维弹性薄板模型，研究弹性波在混凝土防渗墙中的传播、衰减、反射、透射规律及能量分配关系；从分辨率的概念出发，提出了垂直反射法检测混凝土防渗墙分辨率的内涵，对影响分辨率的因素进行了分析，推导出了缺陷层复合反射系数、可检测缺陷层极限厚度的表达式；建立了垂直反射法采样系统各环节之间的关系，研究分析了震源特性、接收传感器对测试结果的影响，提出了对测试仪器参数的要求及采集参数的选择原则。

The breaking of gravity wave accelerates the downward transport of atomic oxygen, some smaller-scale structures appear on the horizontal distribution of atomic oxygen number density , and other chemical species are also affected due to the chemical reaction with atomic oxygen and the propagation of gravity wave. The OH airglow volume emission rate has an obvious response to the breaking gravity wave and atomic oxygen. The nonlinear propagation of smaller vertical wavelength gravity waves can induce the double-peaked structure in the OH airglow. The results can explanation some sporadic measurements of OH airglow and can provide a good indication for studying the characteristic of nonlinear gravity wave by using OH airglow measurement.

在重力波的传播过程中，氢氧大气成分的水平和垂直分布均受到了不同程度的影响，以氧原子的响应最为明显，而其中重力波破碎在氧原子水平分布上的反应则是非线性重力波过程的一个重要表现；另外，分析显示，重力波的非线性传播对OH气辉的峰值分布由明显影响，小尺度重力波的传播有时会引起OH气辉出现奇异的双峰分布，重力波的破碎现象也可以从对气辉的观测中反映应出来，这对利用气辉观测研究重力波传播特性有非常重要的指示意义。

The propagation matrix method used widely in stratified media is extended to laterally inho-mogeneous media,and a numerical method known as generalized propagation matrix method for simulating elastic seismic wave propagation in inhomogeneous media is presented by using mixed variable elastic wave equation and matrix exponent solution of system of linear ordinary differential equations.

应用混合变量弹性动力学方程和线性常微分方程组的矩阵指数解法，将层状介质中广泛应用的弹性波传播矩阵解法推广至横向非均匀介质，给出了一种可计算复杂地质体中弹性波传播的广义传播矩阵数值解法。

The first is termed aero-optic and involved optical transmission through aberrating fluid layer whose thickness, L, is smaller than or comparable with the viewing aperture dimension, A, and the turbulence scales, A , are smaller than or the order as the layers thickness:The second category, atmospheric propagation, involved optical transmission through the aberrating medium over very long propagation distance compare with the viewing aperture size, and the turbulent scales of note are generally less than or the same order as the propagation distance:Depending on the atmospheric conditions, for ground-based observatories, wave-front sensor operating at 300HZ can adequately resolved both the important spatial scales and the temporal evolution of the atmospheric-turbulence-induced aberrating wave front over viewing aperture associated with relatively large telescope.

第一类问题光学畸变发生在&近场&较短的光路上，即流层厚度L，光束直径A，以及湍流尺度Λ三者之间存在关系式：ΛA≤L≤A第二类大气传输问题光学畸变则发生在较长的一段光路上，L，A，以及Λ满足： A＜＜Λ≤L对于地基情况下的大气光学传输，300Hz的波前传感器就能实时地测得光波前畸变包括时间、空间频率的相关信息，为我们的自适应光学系统的设计、制造以及进行相关的自适应校正都有着相当重要的指导意义。

Experimental investigation indicates that shock wave velocity and shock wave pressure of beginning which were produced with aluminize RHTL were smaller than that of insensitive RDX in steel plate, however, attenuating velocity of shock wave velocity and shock wave pressure which were produced under contact explosion with aluminize RHTL were quciker than that of insensitive RDX in steel plate, when steel- plate had been separately operated under contact explosion with insensitive RDX and aluminize RHTL, and shock wave press had changed suddenly in the interface between steel and aluminum, In the circumstances, the shock wave velocity had ascended suddenly and shock wave pressure had descended suddenly.

实验研究表明：RHTL炸药爆炸加载钢板下，介质中的冲击波初始速度和初始压力相对RDX较小，衰减相对较快；钝化RDX和含铝炸药RHTL分别作用于钢铝复合板时，在分界面处冲击波速度和压力都发生突越，冲击波速度突跃，冲击波压力突降。

The main results can beexpressed as follows:(1)Based on πtheory, some affected factors about wave forces are given, and therelation between affected factors and wave forces is analysised by experimentalresults.(2) The distribution of wave press at representative time and reflection nature aregiven and their variety charactes are discussed by experimental results.(3)By comparing the wave forces of quarter-circular breakwater and semi-circularbreakwater under the same wave conditions,some approximately wave forcesexpressions of quarter-circular breakwater are given.(4)Based on VOF method to trace water free surface,solve numerical value ofRANS equation,and get the distributions of flow field and wave press ofquarter-circular breakwater at the same time during one period,the mechanism ofwave force is also discussed elementarily.(5) Based on the result that RANS equation of numerical simulation agree wellwith experimental results,a new approach to study hydraulic natures of quarter-circular breakwater is provided.

其主要结论如下：一、通过π定理，确定影响波浪力的无因次参变量，根据试验结果对其影响因素进行分析；二、基于模型试验，给出典型时刻圆弧面防波堤的同步波压分布和反射特性，讨论它们的变化特点；三、通过相同条件下圆弧面防波堤与半圆型防波堤两种堤型试验波浪力的比较，给出了圆弧面防波堤波浪力的近似方法；四、利用VOF法追踪自由水面，数值求解RANS方程，得到圆弧堤堤体周围的流场和压力场，初步分析了速度涡流与压力场的相互影响；五、对比数值分析与试验结果，探讨数值方法研究圆弧面防波堤水力特性的可行性，提供新的研究途径

The wave is the core problem of low Fr. current .In order to make diffluent piers with low ridge to be popularized and applied, the surface wave of low Fr. current is chosen as the research object .We measure the surface wave elements and the velocity distribution of various diffluent piers scheme by the experiment of physical model. We also analyze the average wave height, the the average value of the square of wave , unit width of the waves energy , the probability density distribution of wave height ,and the power chart character, so as to reveal the weakening wave mechanism of the diffluent piers .

低Fr水流的核心是波浪问题，为了低坎分流墩的推广应用，本研究以低Fr水流的表面波浪作为研究对象，通过物理模型试验，对各种分流墩方案消能工的下游水面波浪要素、流速分布进行测试，分析低坎分流墩下游波浪的平均波高、均方根、单宽波能、波高概率密度分布及功率谱特性变化规律，从而揭示了低坎分流墩的削波机理。

In the days of sailing vessels the crew were afraid they would be becalmed on the ocean.

在使用帆船的时代，船员们担心他们会因为无风而无法在海洋上航行。

As long as foreign donors pay the PA's salary bill, few expect a new intifada.

只要外国继续为巴权力机构的薪水买单，希望发动新暴动的人便寥寥无几。