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We are concerned with the acoustic scattering problem by many small rigid obstacles of arbitrary shapes. We give a sufficient condition on the number $M$ and the diameter $a$ of the obstacles as well as the minimum distance $d$ between them…

偏微分方程分析 · 数学 2016-10-20 Durga Prasad Challa , Mourad Sini

In theory, active control could be used to reduce the unwanted noise reflections from surfaces such as a submarine hull or the walls of an anechoic room. In the recent years, a real-time algorithm has been developed to this effect at the…

经典物理 · 物理学 2009-11-25 Emmanuel Friot , Alexandre Gintz

We report theoretical and experimental results for a new type of homogenized acoustic metamaterials with negative effective mass density. We constructed one-dimensional metamaterial, which is a tube with an array of very thin elastic…

材料科学 · 物理学 2009-11-30 Sam Hyeon Lee , Choon Mahn Park , Yong Mun Seo , Zhi Guo Wang , Chul Koo Kim

An increasing number of young circumstellar disks show strikingly ordered (sub)millimeter polarization orientations along the minor axis, which is strong evidence for polarization due to scattering by ~0.1 mm sized grains. To test this…

地球与行星天体物理 · 物理学 2020-06-10 Zhe-Yu Daniel Lin , Zhi-Yun Li , Haifeng Yang , Leslie Looney , Ian Stephens , Charles L. H. Hull

The special symmetry properties of the discrete nonlinear Schrodinger equation allow a complete revival of the initial wavefunction. That is employed in the context of stationary propagation of light in a waveguide array. As an inverting…

光学 · 物理学 2015-06-12 Ramaz Khomeriki , Lasha Tkeshelashvili

This paper is concerned with acoustic scattering from a sound-soft trapezoidal surface in two dimensions. The trapezoidal surface is supposed to consist of two horizontal half-lines pointing oppositely, and a single finite vertical line…

数值分析 · 数学 2019-03-19 Wangtao Lu , Guanghui Hu

We simulate and discuss novel spatio-temporal propagation effects that relate specifically to pulsed, phase-mismatched second harmonic generation in a negative index material having finite length. Using a generic Drude model for the…

Metamaterials are effectively homogeneous materials that display extraordinary dispersion. Negative index metamaterials, zero index metamaterials and extremely anisotropic metamaterials are just a few examples. Instead of using locally…

The identification of the refractive index and wave vector for general (possibly active) linear, isotropic, homogeneous, and non-spatially dispersive media is discussed. Correct conditions for negative refraction necessarily include the…

光学 · 物理学 2009-11-13 Johannes Skaar

The properties of artificial isotropic microwave composites which would possess simultaneously negative permittivity and permeability are studied theoretically. Four kinds of composites are considered. Two of them concern media with…

材料科学 · 物理学 2015-06-24 C. R. Simovski , B. Sauviac

We derive an approach to define the causal direction of the wavevector of modes in optical metamaterials, which in turn, determines signs of refractive index and impedance as a function of {\it real and imaginary} parts of dielectric…

Since the introduction of the artificially designed negative-index metamaterial (NIM) introduced in 2001, its extraordinary electromagnetic properties, which cannot be attained from naturally occurring materials, have continuously attracted…

光学 · 物理学 2013-01-17 Boyi Gong , Xiaopeng Zhao , Zhenzhen Pan , Sa Li , Xiaonong Wang , Yan Zhao , Chunrong Luo

The diffraction of electromagnetic plane waves by a rectangular grating formed by discrete steps in the interface of a homogeneous, isotropic, linear, negative phase--velocity (negative index) material with free space is studied using the…

光学 · 物理学 2009-11-11 Ricardo A. Depine , Akhlesh Lakhtakia , David R. Smith

In this paper, we have presented an analytical solution to extract the effective properties of acoustic metamaterials from the measured complex transmission and reflection coefficients when the metamaterial and impedance tube have different…

声音 · 计算机科学 2024-06-19 Mohammad Javad Khodaei , Amin Mehrvarz , Reza Ghaffarivardavagh , Nader Jalili

Negative refraction provides an attractive platform to manipulate mid-infrared and terahertz radiation for molecular sensing and thermal radiation applications. However, its implementation based on available metamaterials and plasmonic…

We build an effective medium theory for two-dimensional photonic crystals comprising a rectangular lattice of dielectric cylinders with the incident electric field polarized along the axis of the cylinders. In particular, we discuss the…

光学 · 物理学 2016-03-23 Meng Xiao , Xueqin Huang , Anan Fang , C. T. Chan

A method is proposed to create materials with a desired refraction coefficient, possibly negative one. The method consists of embedding into a given material small particles. Given $n_0(x)$, the refraction coefficient of the original…

数学物理 · 物理学 2009-11-13 A. G. Ramm

In this article, it has been theoretically shown that broad angle negative refraction is possible with asymmetric anisotropic metamaterials constructed by only dielectrics or loss less semiconductors at the telecommunication and relative…

光学 · 物理学 2015-12-09 Ayed Al Sayem , Mahdy Rahman Chowdhury Mahdy , Md. Saifur Rahman

We performed high-resolution Fourier-transform infrared (FTIR) spectroscopy of a polymethyl methacrylate (PMMA) sphere of unknown size in the Mie scattering region. Apart from a slow, oscillatory structure (wiggles), which is due to an…

光学 · 物理学 2016-05-24 R. Blümel , M. Bağcıoğlu , R. Lukacs , A. Kohler

We investigate the acoustic properties of meta-materials that are inspired by sound-absorbing structures. We show that it is possible to construct meta-materials with frequency-dependent effective properties, with large and/or negative…

偏微分方程分析 · 数学 2016-03-18 Agnes Lamacz , Ben Schweizer