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Imaging of effective medium parameters of random medium contaioning many particles

多颗粒随机介质有效介质参数成像

基本信息

批准号：
15560370
负责人：
NANBU Yukihisa
金额：
$ 1.92万
依托单位：
Sasebo National College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Materials in nature have been used to design many kinds of electromagnetic devices or functional elements, while artificial materials are studied in order to develop more sophisticated devices. One of them has been proposed by mixing many particles. In the future utilization, it will become more important to examine electromagnetic properties of them at high frequencies. This means that multiple scattering of waves between particles plays a central role in the determination of material properties. One of important parameters to know the electromagnetic properties of the composite material is the effective propagation constant of the medium. They have been obtained through several approaches. However, most researches have dealt with simple composite medium of particles having just one kind of property or symmetry shaped like a sphere or a cylinder. If materials are composed of particles with several kinds of properties and/or with complex shapes, the composite materials are expected to … More possess more interesting characteristics. The following are conclusions in our research.(1)We have analyzed the effective constitutive parameters for a random medium in which many chiral spheres are distributed by using our approach. The approach is based on an unconventional multiple scattering method by which wave scattering can be systematically treated in a medium whose dielectric particles are randomly displaced from a uniformly ordered spatial distribution. The effective constitutive parameters are estimated by changing the volume fraction, dielectric constant and chirality of the chiral spheres. The results were compared with those of the random medium with dielectric spheres to make clear the characteristics of the effective constitutive parameters of the chiral random medium.(2)We assumed a composite medium containing pairs of chiral or dielectric spheres (aggregate spheres) and numerically evaluated the effective propagation constant of the medium. For chiral materials, it was common to discuss its characteristics by decomposing into the left- and right-handed polarizations. First, we obtained a T-Matrix of the aggregate sphere by using recursive algorithm. Second, multiple scattering equations with the T-Matrix are solved by applying Effective Field Approximation (EFA) to estimate the effective propagation constants for left- and right-handed polarizations. The characteristics of the effective propagation constants was made clear by changing the electromagnetic properties of particles. Less

自然界中的材料已被用于设计各种电磁器件或功能元件，而人工材料的研究是为了开发更复杂的器件。其中之一是通过混合许多粒子提出的。在未来的应用中，研究其高频电磁特性将变得更加重要。这意味着粒子间波的多次散射在确定材料特性中起着核心作用。介质的有效传播常数是了解复合材料电磁特性的重要参数之一。它们是通过几种方法获得的。然而，大多数的研究都是处理简单的复合介质的粒子只有一种性质或对称形状像一个球体或圆柱体。如果材料由具有多种性质和/或具有复杂形状的颗粒组成，则期望复合材料 ...更多信息拥有更有趣的特性。以下是我们在研究中得出的结论。(1)We用我们的方法分析了随机介质中分布有许多手征球的有效本构参数。该方法是基于一种非常规的多次散射方法，通过该方法可以系统地处理介质中的介质，其电介质颗粒从均匀有序的空间分布随机移位的波散射。通过改变手征球的体积分数、介电常数和手征性来估计有效本构参数。将所得结果与含介质球的随机介质的结果进行了比较，明确了手征随机介质有效本构参数的特点。(2)We假设一个复合介质包含手性或介电球（聚合球）对，并数值计算了介质的有效传播常数。对于手征材料，通常将其分解为左手和右手极化来讨论其特性。首先，利用递归算法得到凝聚球的T矩阵。其次，多重散射方程的T矩阵求解应用有效场近似（EFA）估计的有效传播常数的左，右手极化。通过改变粒子的电磁特性，明确了有效传播常数的特性。少