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Quasi-lossless and asymmetric sound transports, which are exceedingly desirable in various modern physical systems, are almost based on nonlinear or angular-momentum biasing effects with extremely high power levels and complex modulation…

We extend earlier numerical and analytical considerations of the conformally invariant wave equation on a Schwarzschild background from the case of spherically symmetric solutions, discussed in Class. Quantum Grav. 34, 045005 (2017), to the…

General Relativity and Quantum Cosmology · Physics 2018-02-23 Jörg Frauendiener , Jörg Hennig

We study acoustic wave propagation in a uniform stationary flow. We develop a method founded on the Lorentz transform and a hypothesis of irrotationality of the acoustic perturbation. After a transformation of the space-time and of the…

Numerical Analysis · Mathematics 2011-05-10 François Dubois , Eric Duceau , Frédéric Marechal , Isabelle Terrasse

We study the local dynamics of $L^{2}\left(\mathbb{R}\right)$-perturbations to the zero solution of spatially $2\pi$-periodic coefficient reaction-diffusion systems. In this case the spectrum of the linearization about the zero solution is…

Analysis of PDEs · Mathematics 2019-03-01 Connor Smith

We propose an exactly solvable waveguide lattice incorporating inhomogeneous coupling coefficient. This structure provides a classical analogue to the squeezed number and squeezed coherent intensity distribution in quantum optics where the…

This note analytically investigates non-reciprocal wave dispersion in locally resonant acoustic metamaterials. Dispersion relations associated with space-time varying modulations of inertial and stiffness parameters of the base material and…

Applied Physics · Physics 2018-01-11 M. A. Attarzadeh , H. Al Ba'ba'a , M. Nouh

In image and audio signal classification, a major problem is to build stable representations that are invariant under rigid motions and, more generally, to small diffeomorphisms. Translation invariant representations of signals in…

Functional Analysis · Mathematics 2019-03-08 Jameson Cahill , Andres Contreras , Andres Contreras Hip

Unraveling real eigenfrequencies in non-Hermitian $\mathcal{PT}$-symmetric Hamiltonians has opened new avenues in quantum physics, photonics, and most recently, phononics. However, the existing literature squarely focuses on exploiting such…

Classical Physics · Physics 2022-10-07 M. Moghaddaszadeh , M. A. Attarzadeh , A. Aref , M. Nouh

In this paper, we study concentration phenomena of zero-noise limits of invariant measures for stochastic differential equations defined on $\mathbb{R}^d$ with locally Lipschitz continuous coefficients and more than one ergodic state. Under…

Probability · Mathematics 2022-02-16 Zhao Dong , Fan Gu , Liang Li

We consider the time-harmonic acoustic wave scattering by a bounded {\it anisotropic inhomogeneity} embedded in an unbounded {\it anisotropic} homogeneous medium. The material parameters may have discontinuities across the interface between…

Analysis of PDEs · Mathematics 2018-12-26 Otar Chkadua , Sergey E. Mikhailov , David Natroshvili

We study the scalar, conformally invariant wave equation on a four-dimensional Minkowski background in spherical symmetry, using a fully pseudospectral numerical scheme. Thereby, our main interest is in a suitable treatment of spatial…

General Relativity and Quantum Cosmology · Physics 2014-04-03 Jörg Frauendiener , Jörg Hennig

We embark on a systematic study of continuous non-invertible symmetries, focusing on 1+1d CFTs. We describe a generalized version of Noether's theorem, where continuous non-invertible symmetries are associated to $\textit{non-local}$…

High Energy Physics - Theory · Physics 2025-08-18 Diego Delmastro , Adar Sharon , Yunqin Zheng

We propose and demonstrate a novel method for generating propagation-invariant spatially-stationary fields in a controllable manner. Our method relies on producing incoherent mixtures of plane waves using planar primary sources that are…

The recent identification of a modulation of acoustic waves that is driven by spatial velocity gradients, using acoustic black and white hole analogues [Schenke et al., J. Acoust. Soc. Am. 154 (2023), 781-791], has shed new light on the…

Fluid Dynamics · Physics 2024-02-06 Fabian Denner

We study an inverse source problem for the acoustic wave equation in a random waveguide. The goal is to estimate the source of waves from measurements of the acoustic pressure at a remote array of sensors. The waveguide effect is due to…

Analysis of PDEs · Mathematics 2015-02-25 Sebastian Acosta , Ricardo Alonso , Liliana Borcea

Ever since a new symmetry was found for the imperfect fluid with vorticity the question of the effect of perturbations on the symmetry itself has been raised. This new symmetry arose when realizing that local four-velocity gauge-like…

General Relativity and Quantum Cosmology · Physics 2026-03-24 Alcides Garat

This paper is devoted to investigating the rotating Boussinesq equations of inviscid, incompressible flows with both fast Rossby waves and fast internal gravity waves. The main objective is to establish a rigorous derivation and…

Analysis of PDEs · Mathematics 2023-04-18 Claude Bardos , Xin Liu , Edriss S. Titi

The present paper concerns the well-posedness of the Cauchy problem for microlocally symmetrizable hyperbolic systems whose coefficients and symmetrizer are log-Lipschitz continuous, uniformly in time and space variables. For the global in…

Analysis of PDEs · Mathematics 2016-10-14 Ferruccio Colombini , Daniele Del Santo , Francesco Fanelli , Guy Métivier

In this work, we consider the propagation of acoustic waves in unbounded domains characterized by a constant wavenumber, except possibly in a bounded region. The geometry of this inhomogeneity is assumed to be uncertain, and we are…

Numerical Analysis · Mathematics 2024-07-17 Fernando Henríquez , Ignacio Labarca-Figueroa

We consider a time-harmonic wave problem, appearing for example in water-waves and in acoustics, in a setting such that the analysis reduces to the study of a 2D waveguide problem with a Neumann boundary condition. The geometry is symmetric…

Analysis of PDEs · Mathematics 2018-05-31 Lucas Chesnel , Sergei A. Nazarov , Vincent Pagneux