散射

The angular distribution of the bistaticscattering coefficient of HH polarization were obtained by numerical implementation. Influences of the permittivity and the mean layer thickness of intermediate medium, friction velocity and the frequency of the incident wave on the bistatic scattering coefficient were discussed. The basic characteristics, the zonal characteristics and the characteristics with varying of frequency of the scattering coefficient from stratified sea surface were obtained. The numerical results show that the scattering coefficient has approximate "quantization" characteristics.

通过数值计算得到了HH 极化双站散射系数随散射角的变化曲线，讨论了中间介质介电常数和厚度、摩擦风速和入射波频率对双站散射系数的影响，得到改进的一维分形分层海面散射系数的基本特征、分区特征和随频率变化的特征，结果表明散射系数近似具有"量子化"特征。

Based on AIEM and MIMICS models, the co-relation among radar backscatter, vegetation backscatter and surface backscatter were analyzed, and the linear relation between cross polarization data and vegetation backscatter component was found. Then a simplified vegetation model was constructed after solving the problem of the vegetation backscatter component.

在裸露地表理论模型AIEM和植被散射模型MIMICS模拟分析雷达后向散射与植被散射、地表散射之间相互关系的基础上，分析发现了交叉极化数据与植被体散射量存在的线性关系，从而解决了雷达总后向散射中植被体散射量的问题，进而建立了简化的植被模型。

Since the multiple scattering should be considered, the scattering problem of many-cylinders is more complicated than single cylinder. By using scattering matrix method to solve the scattering problem of many-cylinders, first we have to express the incident fieldand scattered field by special function（for example, Bessel function and Hankel function）under cylindrical coordinate, then use the addition theorem of special function to get a linear system of equations to relate the incident field coefficients and scattered field coefficients. The incident and scattered field coefficients for every cylinder can be solved from the linear equations by matching electromagnetic boundary condition pointwisely.

单颗圆柱散射体的散射场解析解很早就被解出，而多个圆柱阵列的散射场问题因为涉及到入射光在圆柱与圆柱间的多重散射，故散射行为较单颗圆柱的散射复杂，因此圆柱阵列的多重散射问题需要利用加法定理来处理；散射矩阵法的主要精神即是先用圆柱座标下的特殊函数对平面波和圆柱散射体的内外域电磁场做无穷级数展开，再藉由特殊函数的加法定理将所有圆柱散射体的展开中心移到同一个展开中心，最后可以得到一组连结整个散射系统的入射电磁场系数及散射电磁场系数的线性方程组，将该组线性方程配合电磁场在散射体边界的连续条件，便可分别求出圆柱阵列中各个圆柱体的内部电磁场与外部散射场，再利用线性叠加原理即可求得整个圆柱系统的全域电磁场分布。

Drift electron mobility, the Hall factor and Hall mobility in GaN are calculated according to Mattiessen's rule as a function of temperature for carrier concentrations with the compensation ration as a parameter on the basis of taking into account the individual average scattering momentum relaxation time of four scattering mechanisms, namely, ionized impurity scattering, polar mode optical scattering, acoustic piezoelectric scattering and acoustic phonon deformation potential scattering which have an effect on electron mobility of GaN.

考虑了对纤锌矿型氮化镓低场电子输运影响最为显著的4种散射机制－电离杂质散射，极化光学波散射，声学波压电散射和声学声子形变势散射的单个平均动量驰豫时间，采用Mattiessen's rule计算了不同补偿率以及不同载流子浓度条件下，氮化镓电子漂移迁移率，霍耳因子以及霍耳迁移率随温度的变化。

The research achievement are acquired as follows: 1From mathematical models for inverse scattering in two dimensional homogenous media including Dirichlet, Neumann, Robin,all kinds of probable mixed boundaries and cracks, direct and inverse scattering are discussed, and ill-posed integral equation and indicator function method are formulated for the diverse of boundary identification. It is shown that the kernel of the integral equation characters the boundary of scatterer, which is determined by solving it by virtual of regularity method, meanwhile, some numerical tests are given.

本研究取得了如下研究成果： 1）在二维均匀介质逆散射各种边界识别的数学模型（包括Dirichlet，Neumann，Robin，各种可能的混合边界问题，裂纹问题）下，分别考虑了正散射问题和逆散射问题，推导了上述各种边界识别的不适定积分方程以及指示函数方法，由于积分方程的核充分表征了散射物的边界，由此说明只要利用正则化方法求解该积分方程，就可以确定散射物的边界，并给出了一些数值实验。

The results show that the scattered radiant intensity is always symmetric with respect to the polarization plane, and that the scattered intensity is sensitive to the scattering particle size regardless of the incident radiation polarization, and finally, that the vertical components in the scattered light are totally different distribution for two kinds of polarized radiation.

散射粒子直径分别为：1.24μm、0.494μm、0.36μm、0.123μm、0.065μm。以粒子与水技不同比例混合液，作为散射粒子场。所得结果表明，散射光强度总是相对入射光束的偏振面呈对称分布；散射光强度对散射粒子大小敏感而与入射光偏振态无关；散射光中垂直偏振分量在两种光入射下存在完全不同的状态分布。

From the simulation,the distribution of single and bulk scattering was obtained and it was found that the scattering distribution was focused in forward scattering at a small angle,and that the scattered laser might be absolute polarized light.

通过模拟得到单分系和多分系的散射分布特征，得出散射强度主要集中在前向小角度散射的结论，并讨论了散射光的偏振特性，得出散射光存在完全偏振光的结论。

Especially the deficiencies of the research work in scattered wave numerical simulation and its applications were summed up:①geometry is unseemliness;②lack of study systematically in the scattered wave field characteristic;③lack of study systematically in the scattered wave field recognize and its interpretation;④lack of the program for scattering image.

对散射理论及应用研究成果进行了系统评述，特别对前人关于散射波数值模拟和应用研究的不足进行了总结：(1)观测系统设计不合理；(2)对散射波的特征研究缺乏系统性；(3)对复杂散射波场的识别方法没有进行系统研究；(4)适合散射成像的处理软件还有待开发。

Based on the Lorentz-Mie theory, the single scattering characteristics of multi-dispersed spherical and multi-layered spherical particles are studied. The extinction coefficients, scattering coefficients, single albedos, single scattering phase functions and asymmetry factors of different clouds are presented. Numerical results for single scattering of spherical and non-spherical particles are obtained in the approximation of geometrical optics. The single scattering phase matrixes of non-spherical aerosols are calculated by using the T matrix method.

基于洛伦茨-米理论研究了服从一定尺寸分布的球形和多层球形粒子的单次散射特性，计算了各种不同类型云层的消光系数、散射系数、单次散射反照率、单次散射相函数以及不对称因子；利用几何光学方法计算了球形、非球形粒子的单次散射特性；利用T矩阵方法计算了非球形气溶胶的单次散射相矩阵。

This paper introduces the studies of the ultra-short Thomson scattering X-ray source at the accelerator laboratory of Tsinghua University in recent years. Properties such as the photon yield,the pulse length and time jitter of the produced photon pulse were predicted theoretically from the parameters of the electron bunch and the laser pulse,and the scattering angle. Preliminary experiments were successfully carried out with a 16 MeV backward-traveling-wave accelerator and the ns-Q switched laser provided by China Academy of Engineering Physics. This paper also introduces the 1.6-cell electron gun that was fabricated on site and the experiment with high RF power including the measurement of the electron bunche parameters. Based on these,we have designed an X-ray source,which is now under construction.

介绍了清华大学加速器实验室近年来关于汤姆逊散射超短X射线源的研究工作；研究了在任意散射角度下电子束参数和激光束参数对散射光子参数的影响，给出了散射光子的参数如光子产额、脉冲长度、时间抖动等与电子束参数、激光束参数和散射角度的关系；利用实验室已有的16 MeV反波行波加速器与中国工程物理研究院激光聚变研究中心提供的ns调Q激光搭建了汤姆逊散射初步实验平台并开展了实验研究；加工了1.6-cell光阴极微波电子枪，搭建了高功率实验平台，对产生的电子束参数进行了初步测量；对汤姆逊散射超短X射线源进行了设计并开展了相关的平台建设工作，对产生的X射线脉冲参数进行了模拟。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。