In this paper, we present an accurate method of moments (MoM) solution of the combined field integral equation (CFIE) using the multilevel fast multipole algorithm (MLFMA) for scattering by large, three-dimensional (3-D), arbitrarily shaped, homogeneous objects. We first investigate several different MoM formulations of CFIE and propose a new formulation, which is both accurate and free of interior resonances. We then employ MLFMA to significantly reduce the memory requirement and computational complexity of the MoM solution. Numerical results are presented to demonstrate the accuracy and capability of the proposed method. The method can be extended in a straightforward manner to scatterers composed of different homogeneous dielectric and conducting objects.

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Based on the different characteristics of memory requirement and CPU time at different levels in the Multi-Level Fast Multipole Algorithm (MLFMA), a new highly efficient parallel approach is proposed, which employs different techniques to parallelize the plane waves and translation matrices at different levels. The formulae for efficiently implementing this proposed approach are presented by theoretical analysis and numerical experiments. Several techniques have also been employed to reduce memory requirement. The proposed parallel approach is implemented and investigated numerically, showing that the proposed approach is very accurate and efficient. The radar cross-section (RCS) of a conducting sphere with a diameter of 144λ (wavelength), simulated by over 10 millions unknowns, is successfully computed in the Center for Electromagnetic Simulation (CEMS) in the Beijing Institute of Technology (BIT), demonstrating the strong computation power of this proposed approach. The comparison of numerical performance between Center for Computation Electromagnetics (CCEM) in University of Illinois at Urbana-Champaign (UIUC) and our CEMS is also presented in this paper.

A male Morpho peleides butterfly wing is decorated by two types of scales, cover and ground scales. We have studied the optical properties of each type of scales in conjunction with the structural information provided by cross-sectional transmission electron microscopy and computer simulation. The shining blue color is mainly from the Bragg reflection of the one-dimensional photonic structure, e.g., the shelf structure packed regularly in each ridges on cover scales. A thin-film-like interference effect from the base plate of the cover scale enhances such blue color and further gives extra reflection peaks in the infrared and ultraviolet regions. The analogy in the spectra acquired from the original wing and that from the cover scales suggests that the cover scales take a dominant role in its structural color. This study provides insight of using the biotemplates for fabricating smart photonic structures.