散射

ABSTRACT The dissertation consists of the polarization theory and the scattering theory of polarization including the exact solution for the scattering of plane wave by a chiral elliptic cylinder and the polarization of scattered wave.

本文主要研究了极化理论及目标的极化散射特性，包括研究旋波媒质的电磁极化散射特性，首次给出了旋波媒质椭圆柱散射问题的精确解析解，同时对其散射的极化特性进行了分析。

The analysis indicates that the mean intensity distribution on the receiver plane is closely related to the ratio of the lateral correlation length to the surface root mean square height.

研究了粗糙目标对相干光场的散射，导出了在接收平面上光场的自相关函数、光强度的分布和光强度的二阶矩，在分析粗糙目标对激光脉冲后向散射的基础上，提出了后向散射光强度与目标均方根高度和相关长度的关系，阐明了粗糙目标的后向散射机理。

The main results are as following: A A new demonstration to optical theorem is constructed B The scattering amplitude function for small particles, which is more accurate than that in classical RGB, is gained using electrostatics approximation, C Through a δ transform to the high frequent oscillation function, a concise deduction of the EG-type scattering amplitude function has been achieved.

主要结果如下： A给出了光学定理的一个新证法； B利用静场近似，得到了比经典RGB更精确的小粒子散射振幅函数； C通过一个高频振荡函数的δ变换，给出了一种EG散射振幅表达式的简明推导，并做了小角度散射简化，参照ADT，对EG近似又做了相位修正； D定义了一个新的函数—消光函数，并得到了组合散射体消光函数的平均定理。

This dissertation involves the study of the growth dynamics of colloidal particles under unequilibrium and irreversibility condition. Firstly, it is of interest to investigate whether the ideal diffusion or reaction-limited aggregation universal behavior can be observed for the initially polydisperse practical system of basic yttrium carbonate as well. The fractal structure of basic yttrium carbonate aggregate cluster was observed using transmission eletron microscopy. The aggregation kinetics of basic yttrium carbonate colloids was studed using dynamic 1ight-scattering techniques. At 1.00mol/l NaCl solution the fast diffusion-limited aggregation behavior was observed with an increase in the aggregate size over time described by a power law. The aggregates are characterized by a fractal dimension D=1.82. The disordered and ramified cluster is consisted of primary colloidal particles and tenuous and more open. These are in good agreement with those observed for other colloidal system such as colloidal gold (1.86), silica (1.85) and polystyrene latex (1.82) in diffusion-limited aggregation from the static and dynamic light scattering by Lin. Therefore ideal diffusion-limited aggregation behavior can be observed in practical polydisperse system as well. Smoluchwski and fractal theories were used to obtain the aggregation rate constant for initially polydisperse system for the first time.

本论文研究胶粒的非平衡不可逆聚集动态学，分为两个部分，第一部分是通过实验研究一个新的初始多分散的碱式碳酸钇胶粒实际体系中，聚集标度性质的普适性，即使用透射电子显微技术观测聚集粒子簇的分形结构，使用动态激光光散射研究碱式碳酸钇胶粒的聚集动力学，胶粒带电而产生静电排斥作用使得碱式碳酸钇胶粒处于稳定状态，当加入电解质NaCl溶液时，碱式碳酸钇胶粒间的Debye-Hückel屏蔽距离缩短，从而降低静电排斥能垒，引起胶粒发生不可逆聚集，加入电解质NaCl的浓度为1.00mol/l时，碱式碳酸钇胶粒进行快速聚集，经历扩散控制聚集机理，形成结构疏松、更为开放的分形聚集粒子簇，其分形维数为1.82，碱式碳酸钇胶粒聚集增长动力学遵循幂函数增长规律，与Lin等使用静态激光光散射和动态激光光散射测量硅胶(1.85)、金胶(1.86)和聚苯乙烯胶乳(1.82)在扩散控制聚集状态形成聚集粒子簇的分形维数值以及粒子簇聚集增长的动力学规律相一致，表明胶粒聚集标度性质的普适性质在初始多分散的实际体系中也是存在的，首次由动态激光光散射的实验数据得到初始多分散胶粒分形粒子簇的聚集速率常数，并且其值与Smoluchowski聚集速率理论预期相符。

In order to overcome this problem, in this paper, the surface electric current of the conducting sea surface and the first-order scattering from the conducting plate are obtained by employing Physic Optics method. The backscattering field of the time-dependant sea surface is calculated by using Kirchhoff Approximation. Meanwhile, taking the advantage of a newly developed technique that utilizes the reciprocity theorem, the difficulty in formulating the secondary scattered fields from the composite target is reduced. The dependences of the backscattered field on the parameters, such as the wind speed and the sizes of the plate are discussed.

为了克服这一问题，本文应用物理光学近似求解了导体海面表面电流及导体平板的一阶散射场，应用基尔霍夫近似给出了海面的后向散射场，同时借助互易性定理降低了求解平板和海面之间二次耦合散射场的难度，讨论了平板尺寸、风速等对后向复合散射场的影响。

Based on the above results, the problems of the electromagnetic interaction between a perfect conducting plate and 1-D/2-D conducting slightly random rough surface and the problems of the electromagnetic interaction between a dielectric spherical particle and dielectric slightly random rough surface are investigated. By using the reciprocity theorem, Small Perturbation Method and Physical Optics approximation, the solution for the composite scattering field from the composite target is derived and evaluated, and the numerical results are discussed and analyzed.

在此基础上，用互易性原理分别研究了一维、二维导体微粗糙面与其上方金属导体平板目标的复合电磁散射及介质粗糙面与其上方球形粒子的复合电磁散射，结合互易性原理和粗糙面散射微扰法及物理光学近似导出了复合散射场的计算公式并进行了数值计算，对计算结果进行了讨论和分析。

For computer simulation of our new reconstruction algorithm, which is only valid for some special scatterers, the corresponding direct scattering data are indispensable and some are given for several scatterer models out of such consideration.

进行重建计算机模拟计算，需要正散射数据，又因本文给出的重建算法目前只对满足特定条件的散射体才有效，出于这样的考虑，这里给出了若干形状不太复杂的散射体对平面波的散射。

In chapter Five, A simulation method for ultrasound backscattered signal is proposed, which take involves ultrasound propagation in soft tissues and its interaction with tissues and different kinds of scattering patterns in tissues. A new scatterer spacing imaging method based on wavelet transform theory has been developed.

第五章提出了基于散射元空间分布的生物软组织的超声背向散射信号建模与仿真的新方法，这种方法的特点是综合考虑了散射元空间概率分布与组织中的超声衰减现象这两种不同类型的效应，同时还考虑了肝脏组织不同类型的散射模式。

With the help of the model,the relationship between the target position deviation angle and the scattering intensity was obtained and the effect of scattered light on the signal was analyzed from the view of scattering.

基于Mie理论，考虑粒子尺度分布函数，得到了群体粒子散射模型，在该基础上，建立了目标方位偏差角与散射光强的关系式，从粒子散射的角度分析了粒子散射光强对回波信号的影响。

Based on the research on the scattering of the Gaussian beam from single sphere, the intensity distributions of LGB beam in different propagation distance is analyzed. Without considering the relationship of scattering and phase shift, the beam coefficients is gained by the solution of scattering cross section, and the LGB is expanded in terms of the vector spherical harmonics as fundamental Gaussian beam. The scattering of the beam with orbital angular momentum from single sphere located on the propagation axis is studied.

在单体球粒子对高斯光束散射研究的基础上，分析了在自由空间不同传输距离LGB光束的光强分布情况，在不考虑散射和波束相移关系的情况下，将LGB作为入射高斯光束，通过对波束入射时的散射衰减截面求解得到波束因子，利用矢量球谐函数对入射高斯波束进行展开，从而研究了单球粒子在在轴条件下对具轨道角动量高斯波束入射的散射问题。

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。