查询词典 diffraction spectrum

X-ray diffraction is one of the most common and efficient ways to measure a superlattice structure. This dissertation displays the detail results for characterization of Ge〓Si〓/Si superlattices by x-ray diffraction (including x-ray small angle diffraction and double crystal diffraction). It was found, when the growth temperature is lower, the intensities of xray small angle diffraction peaks are modulated by a periodical function, which indicates that both sets of interfaces of the superlattice is highly flat; when the growth temperature is higher, the diffraction peak intensities are simply decay with the increase of diffraction vector, which indicates that one set of interfaces is highly flat but another is not; when the growth temperature is very high, the diffraction peaks are reduced more rapidly, which indicates that both sets of interfaces are not ideal.

本文详细介绍了用X-射线衍射（包括X-射线小角衍射和双晶衍射）方法对Ge〓Si〓/Si超晶格结构特性测试的结果，尤其是发现，当Ge〓Si〓/Si超晶格的生长温度较低时，X-射线小角衍射谱峰的强度随着衍射波矢的增加而周期性调制，表明超晶格的两套界面都十分平整；当生长温度较高时，Ge〓Si〓Si超晶格的X-射线小角衍射谱峰的强度随着衍射波矢呈简单的衰减变化，对应于超晶格内有一套界面不平整的情况；当生长温度进一步提高时，X-射线小角衍射峰明显减少，表明超晶格内两套界面都不理想。

The camera length of electron diffraction in transmisson electron microscopy is one of the main technical parameters in designing electron microscope and the electron diffraction analysis to microcrystal sample. According to Bragg law, the formula of calculating TEM electron diffraction camera length is derived from the research on the ray path of electron diffraction images in TEM and the comparison on electron diffraction with ordinary electronic diffractometer. The difference of physical significance of electron diffraction camera length between TEM and ordinary electronic diffractometer is discussed.

透射式电子显微镜(Transmisson Electron Microcopy， TEM)中的电子衍射相机长度，是电子显微镜设计和对微晶体样品进行电子衍射分析的主要技术参数之一依据布拉格定律，经对TEM中电子衍射成像光路的探讨与研究，并通过TEM与普通电子衍射仪的电子衍射的对比分析，导出了TEM电子衍射相机长度的精确计算公式，阐述了TEM和普通电子衍射仪的电子衍射相机长度所表征的物理意义的区别。

To further understand and correctly master the notion of marginal spectrum in Hibert-huang transform, the linear property of marginal spectrum is demonstrated, an mistake to the notion of marginal spectrum in some documents is pointed out, and a new viewpoint about the essential difference between marginal spectrum and Fourier frequency spectrum is put forward by which the amplitude of Fourier frequency spectrum only represents the probability that a frequency objectively exists in a signal while the amplitude of marginal spectrum decides whether a frequency objectively exists in a signal.

为了深入理解和正确掌握希尔伯特－黄变换（Hilbert-Huang Transform，简称HHT）中的边际讲概念，证明了边际谱的线性性质，指出了文献中对边际谱概念的一种误解，提出了边际普与Fourier频谱之间本质区别的一种的新观点，即Fourier频谱的幅值只能反映频率在信号中实际存在的可能性大小，而边际谱的幅值则能真实反映频率在信号中是否存在。

Aiming at this problem, the concept of the second order power spectrum was proposed based on the characteristic of the amplitude tune with periodical notch spectrum in thin layer and theoretically researched. The corresponding relationship between the thickness of thin layers and the maximum value of second order power spectrum was established. The theoretical criteria and method for the thickness estimation by second order power spectrum were given. The second order power spectrum map is made by the energy relationship between the thickness of thin layers and the second order power spectrum, and the time responding to strong energy on the map is the time of thin layer.

为此，从薄层振幅调谐具有周期性陷频谱特征出发，提出了二阶功率谱的概念，从理论上对薄层的二阶功率谱特征进行了研究，建立了薄层厚度与二阶功率谱极大值之间的对应关系，给出了利用二阶功率谱进行薄层厚度预测的理论依据和方法，即根据薄层厚度和二阶功率谱的能量关系制作二阶功率谱图，图上强能量团对应的时间即为薄层时间厚度。

In the aspect of the study of the application of HHT method, This dissertation has done three part of jobs: first, the Elcentro strong ground motion which is in common use in earhtquake engineering is analyzed by HHT method, getting its amplitude-frequency-time distribution and the comparison between the HHT marginal spectrum and Fourier spectrum is also made; second, the typical nonlinear system defined by the Duffing equation is analyzed by HHT method, getting its numerical value's amplitude-frequency-time distribution and the comparison between the HHT marginal spectrum and Fourier spectrum is also made; third, define the stationary degree of non-stationary signals making use of 3-D time-frequency spectrum and marginal spectrum, the stationary degree curve of Elcentro seismic recording is protracted according to its defining formula, the stationary degree curve of Elcentro seismic recording which change with time is protracted according to similiar definition.

在HHT方法的应用研究方面，本文做了三部分的工作：首先，利用HHT方法分析了地震工程中常用的Elcentro非平稳强震记录，得到了该记录的振幅－频率－时间分布特性，并将得到的边际谱与傅立叶谱做了比较；其次，应用HHT方法分析了典型的非线性系统－Duffing方程，得到了该方程数值解的振幅－频率－时间分布特性，并将得到的边际谱与傅立叶谱做了比较；最后，利用三维时频谱与边际谱定义了非平稳信号的平稳度，并依照其定义式绘制了Elcentro地震波记录的平稳度曲线，依照类似与依赖与频率变化的平稳度定义，初步尝试编程绘制了Elcentro地震波随时间变化的平稳度曲线。

Based on the relations of the diffraction field and the surface wave, which conclude diffraction factor and interference factor, some relations were conformed such as: the diffraction fringes spatial distribution versus surface wavelength, the fringes half angular width versus the numbers of surface wave covered by laser spots and incidence angle, diffraction intensity versus surface wave amplitude.

通过对衍射因子和干涉因子的分析，得到衍射条纹空间分布与表面波波长的关系、条纹的半角宽度与入射激光光斑覆盖表面波的个数和入射方向的关系、衍射光强度与表面波振幅的关系，并解释了条纹缺级现象。

The principle of the two dimensional acoustooptic Q switch is presented,the formulas of the diffraction efficiency and diffraction loss of the AO Q switch with normal Bragg diffraction is derived,the relationship between One dimensional and Two dimensional Bragg diffraction is analyzed.

描述了两维声光Q开关的基本原理，详细推导出正常布喇格衍射的两维声光Q开关衍射效率和衍射损耗的表达式，分析了两维布喇格衍射和一维布喇格衍射之间的关系，并给出了在驱动功率40W、光束直径5mm、光波长1。

The diffraction theory of Kirchhoff is applied to the four-pinhole aperture diffraction screens, the intensity, the zero-contour of the real and imaginary parts of complex amplitude and the phase distribution in deep Fresnel diffraction region are simulated, and it is found that the bright spots in interference field show central symmetry distribution. When the observation plane close to the diffraction screen, the zero-value points of light intensity can form line segment, on which the eccentricities of the light intensity isoline are close or equal to 1, the intensity changes very fast on both sides of the zero-line of light intensity.

利用基尔霍夫衍射理论计算了四圆孔径衍射屏在菲涅尔深区形成的的干涉光场的强度、零值线和相位的分布，发现干涉光场亮斑关于中心呈对称分布，在距离衍射屏较近的观察面上，光强值为的零点组成光强零值线段，该线段上光强等值线的离心率都接近或等于1，其两侧的光强值变化非常剧烈。

It is showed that in the X-ray diffraction patterns of the interlayer solid solution Ti3Si0.9Al0.3C1.93 and Ti3Si0.8Al0.4C1.93 bulk samples,which were in-situ reactively synthesized by hot-pressing the elemental Ti,Si,Al and C mixed powders,the diffraction peaks of [00L] crystal planes are very weak,there is only a small diffraction peak belonging to the [008],and the diffraction peaks belonging...

结果发现，用热压Ti、Si、Al和C混合粉末原位反应合成的Ti3Si0.9Al0.3C1.93和Ti3Si0.8Al0.4C1.93层间固溶体块体样品的X射线衍射谱中[00L]晶面的衍射峰极其微弱，只有[008]面有一个小的衍射峰，[002]、[004]和[006]面几乎没有衍射峰存在，而该块体样品的粉末的X射线衍射谱中所有[00L]晶面的衍射峰均存在。

As well known, modern laser diffraction has widely used in engineering measurement but it mostly limited in Fraunhofer diffraction because there is simple function between the size to be measured and space of diffraction dark spots and there are no analytic algorithm for Fresnel diffraction.

现代激光技术提供了极为良好的相干光源，该光源在工程测量，特别是衍射测量中得到广泛应用。但在实际应用中，往往局限于夫琅和费衍射，因为夫琅和费衍射法暗斑间距与被测尺寸之间具有很简单的函数关系S-n/d，而菲涅尔衍射光强分布非常复杂，缺乏解析的计算方法。

Continuously improve the production mechanism, to provide customers with better quality products and services.

不断的完善生产机制，给客户提供更优质的产品及服务。

B:Yes, he was the very prize-winner in the court tennis ten years ago?

是的，他是十年前的世界网球冠军。