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We propose a numerical surface integral method to study complex acoustic systems, for interior and exterior problems. The method is based on a parametric representation in terms of the arc's lengths in curvilinear orthogonal coordinates. With this method, any geometry that involves quadric or higher order surfaces, irregular objects or even randomly rough surfaces can be considered. In order to validate the method, the modes in cubic, spherical and cylindrical cavities are calculated and compared to analytical results, which produced very good agreement. In addition, as examples, we calculated the scattering in the far field and the near field by an acoustic sphere and a cylindrical structure with a rough cross-section. [ABSTRACT FROM AUTHOR]

In this work, we propose a two-dimensional photonic crystal-photonic crystal heterostructure that possesses the requirements for exciting an electromagnetic interface mode and investigate its interaction with photonic crystal waveguide modes. To study the interaction and coupling of both types of modes, the proper conditions to excite them are analyzed. Photonic crystal guided modes can appear in nearly any band gap when the photonic crystal has a line of defects within its lattice. Photonic crystal-photonic crystal surface modes can be excited at the junction of two different photonic crystals that share translation symmetry along the interface direction and have overlapped frequency band gaps. When this condition is met, dispersion relations of photonic crystal-photonic crystal surface modes will lie in the common region of both band gaps. Once the proper conditions are provided to excite these two modes, an interaction between them is possible. In the resulting calculations, a symmetric supercell and a plane wave basis are defined to numerically solve the wave equation. [ABSTRACT FROM AUTHOR]

We study the transport properties of classical particles in the ballistic regime trapped in a two-dimensional channel with dephased ripple boundaries. By taking into account small ripple amplitudes, an analytical approximate expression for the classical resistivity is obtained. We show that the resistivity can be increased considerably by dephasing the walls of the channel. Our results are compared with those obtained for a channel composed of flat and sinusoidal boundaries. [ABSTRACT FROM AUTHOR]