One path to acoustic cloaking
Steven A. Cummer,David Schurig +1 more
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TLDR
In this paper, it was shown that the acoustic equations in a fluid are identical in form to the single polarization Maxwell equations via a variable exchange that also preserves boundary conditions, and the existence of transformation-type solutions for the 2D acoustic equations with anisotropic mass via time harmonic simulations of acoustic cloaking.Abstract:
A complete analysis of coordinate transformations in elastic media by Milton et al has shown that, in general, the equations of motion are not form invariant and thus do not admit transformation-type solutions of the type discovered by Pendry et al for electromagnetics. However, in a two-dimensional (2D) geometry, the acoustic equations in a fluid are identical in form to the single polarization Maxwell equations via a variable exchange that also preserves boundary conditions. We confirm the existence of transformation-type solutions for the 2D acoustic equations with anisotropic mass via time harmonic simulations of acoustic cloaking. We discuss the possibilities of experimentally demonstrating acoustic cloaking and analyse why this special equivalence of acoustics and electromagnetics occurs only in 2D.read more
Citations
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Experimental study on negative effective mass in a 1D mass–spring system
TL;DR: In this paper, a mass-spring system with negative effective mass is experimentally realized, and its transmission property is examined in the low-frequency range, where the local resonance of the basic unit is observed and explained by Newton's theory.
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Broadband cylindrical acoustic cloak for linear surface waves in a fluid.
TL;DR: This work describes the first practical realization of a cylindrical cloak for linear surface liquid waves and demonstrates theoretically its unique mechanism using homogenization theory: the cloak behaves as an effective anisotropic fluid characterized by a diagonal stress tensor in acylindrical basis.
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Achieving control of in-plane elastic waves
TL;DR: In this article, the authors derived the elastic properties of a cylindrical cloak for in-plane coupled shear and pressure waves, which is characterized by a rank 4 tensor with spatially varying entries, which are deduced from a geometric transform.
Journal ArticleDOI
Wave attenuation mechanism in an acoustic metamaterial with negative effective mass density
Hsin-Haou Huang,C.T. Sun +1 more
TL;DR: In this article, the wave attenuation and energy transfer mechanisms of a metamaterial having a negative effective mass density were studied from an energy transfer point of view, and it was found that most of the work done by the external force on the lattice system is stored by the internal mass if the forcing frequency is close to the local resonance frequency.
Journal ArticleDOI
Acoustic metamaterial with negative density
TL;DR: In this paper, a one-dimensional acoustic metamaterial with negative effective density using an array of very thin elastic membranes was fabricated, and the authors reported direct observation of negative acceleration in this acoustic medium below 735 Hz.
References
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Magnetism from conductors and enhanced nonlinear phenomena
TL;DR: In this paper, it was shown that microstructures built from nonmagnetic conducting sheets exhibit an effective magnetic permeability /spl mu/sub eff/, which can be tuned to values not accessible in naturally occurring materials.
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Controlling Electromagnetic Fields
TL;DR: This work shows how electromagnetic fields can be redirected at will and proposes a design strategy that has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.
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Metamaterial Electromagnetic Cloak at Microwave Frequencies
David Schurig,Jack J. Mock,B.J. Justice,Steven A. Cummer,John B. Pendry,Anthony F. Starr,David R. Smith +6 more
TL;DR: This work describes here the first practical realization of a cloak of invisibility, constructed with the use of artificially structured metamaterials, designed for operation over a band of microwave frequencies.
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Optical Conformal Mapping
TL;DR: A general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics is developed, which can be applied to escape detection by other electromagnetic waves or sound.
Journal ArticleDOI
Ultrasonic metamaterials with negative modulus
Nicholas X. Fang,Dongjuan Xi,Jianyi Xu,Muralidhar Ambati,Werayut Srituravanich,Cheng Sun,Xiang Zhang +6 more
TL;DR: A new class of ultrasonic metamaterials consisting of an array of subwavelength Helmholtz resonators with designed acoustic inductance and capacitance with an effective dynamic modulus with negative values near the resonance frequency is reported.