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We consider the inverse problem of the reconstruction of the spatially distributed dielectric constant $\varepsilon_{r}\left(\mathbf{x}\right), \ \mathbf{x}\in \mathbb{R}^{3}$, which is an unknown coefficient in the Maxwell's equations,…

Numerical Analysis · Mathematics 2015-06-19 Larisa Beilina , Nguyen Trung Thành , Michael V. Klibanov , John Bondestam Malmberg

We investigate estimating scalar oscillatory integrals by integrating by parts in directions based on $(x_1 \partial_{x_1} f(x) ,..., x_n \partial_{x_n}f(x))$, where $f(x)$ is the phase function. We prove a theorem which provides estimates…

Classical Analysis and ODEs · Mathematics 2024-10-08 Michael Greenblatt

We investigate the fractional diffusion approximation of a kinetic equation in the upper-half plane with diffusive reflection conditions at the boundary. In an appropriate singular limit corresponding to small Knudsen number and long time…

Analysis of PDEs · Mathematics 2019-09-04 Ludovic Cesbron , Antoine Mellet , Marjolaine Puel

Wave scattering from two-dimensional self-affine Dirichlet and Neumann surfaces is studied for the purpose of using the intensity scattered from them to obtain the Hurst exponent and topothesy that characterize the self-affine roughness. By…

Classical Physics · Physics 2018-06-20 Daniel Strand , Torstein Nesse , Jacob B. Kryvi , Torstein Storflor Hegge , Ingve Simonsen

A major issue in harmonic analysis is to capture the phase dependence of frequency representations, which carries important signal properties. It seems that convolutional neural networks have found a way. Over time-series and images,…

Signal Processing · Electrical Eng. & Systems 2019-07-02 Stéphane Mallat , Sixin Zhang , Gaspar Rochette

This is a theoretical study of the interplay of optical phase-conjugation and multiple scattering. We calculate the intensity of light reflected by a phase-conjugating mirror when it is placed behind a disordered medium. We compare the…

A system of linear differential equations with oscillatory decreasing coefficients is considered. The coefficients has the form $t^{-\alpha}a(t)$,~$\alpha>0$, where $a(t)$ is trigonometric polynomial with an arbitrary set of frequencies.…

Classical Analysis and ODEs · Mathematics 2015-11-03 V. Sh. Burd , V. A. Karakulin

We consider the possibility that most of the reflection component, observed in the hard X-ray spectra of Seyfert galaxies, could be formed on an extended medium, at large distance from the central source of primary radiation (e.g. on a…

Astrophysics · Physics 2007-05-23 Julien Malzac , Pierre-Olivier Petrucci

Particle accelerations by a 1D, EM, dispersive pulse in an external magnetic field are investigated. It is found that the well-known cyclotron resonance may be classified into three regimes as the length and/or the amplitude of the pulse…

Plasma Physics · Physics 2007-05-23 Kazuhiro Akimoto , Hitoshi Hojo

The electromagnetic scattering resonances of a non-magnetic object much smaller than the incident wavelength in vacuum can be either described by the electroquasistatic approximation of the Maxwell's equations if its permittivity is…

Mesoscale and Nanoscale Physics · Physics 2020-11-11 Carlo Forestiere , Giovanni Miano , Guglielmo Rubinacci

In this paper, first we present a review of experimental data corresponding to phase retardation per reflection of interferential mirrors. Then, we report our new measurements on both commercial and tailor-made mirrors. To be able to…

Optics · Physics 2023-10-12 J. Agil , B. Letourneur , S. George , R. Battesti , C. Rizzo

The flow phenomena around a rotating elliptic cylinder in a channel is studied numerically. The value of the confinement parameter \beta is varied as \frac{1}{k}, where k = 2, 4, 6, and 8 respectively, to demonstrate the vortex-shedding…

Fluid Dynamics · Physics 2022-12-13 Prateek Gupta , Sibasish Panda , Akhilesh Kumar Sahu , Deepak Kumar

The average power spectrum of a pulse reflected by a disordered medium embedded in an N-mode waveguide decays in time with a power law t^(-p). We show that the exponent p increases from 3/2 to 2 after N^2 scattering times, due to the onset…

Disordered Systems and Neural Networks · Physics 2007-05-23 M. Titov , C. W. J. Beenakker

We are concerned with the inverse scattering problem of recovering an inhomogeneous medium by the associated acoustic wave measurement. We prove that under certain assumptions, a single far-field pattern determines the values of a…

Analysis of PDEs · Mathematics 2020-05-05 Emilia Blåsten , Hongyu Liu

Reflection of a normal incident matter wave by a perfectly reflecting wall moving with a constant velocity is investigated. A surprising phenomenon is found-that if the the wall moves faster than the phase velocity of the incident wave,…

Quantum Physics · Physics 2007-05-23 Pi-Gang Luan , Yee-Mou Kao

Fractional Brownian motion, a stochastic process with long-time correlations between its increments, is a prototypical model for anomalous diffusion. We analyze fractional Brownian motion in the presence of a reflecting wall by means of…

Statistical Mechanics · Physics 2018-02-21 Alexander H. O. Wada , Thomas Vojta

A modification of the Drude dispersive model based on fractional time derivative is presented. The dielectric susceptibility is calculated analytically and simulated numerically, showing a good agreement between theoretical description and…

Computational Physics · Physics 2021-03-23 Karol Karpiński , Sylwia Zielińska - Raczyńska , David Ziemkiewicz

We study theoretically mode conversion and resonant overreflection of magnetohydrodynamic waves in an inhomogeneous plane-stratified plasma in the presence of a nonuniform shear flow, using precise numerical calculations of the reflection…

Plasma Physics · Physics 2022-12-21 Seulong Kim , Kihong Kim

This work is concerned with the propagation of electromagnetic waves in isotropic chiral media and with the effects produced by a plane boundary between two such media. In analogy with the phenomena of reflection and refraction of plane…

Optics · Physics 2007-05-23 Jose F. Nieves , Palash B. Pal

We study a wave equation with a nonlocal time fractional damping term that models the effects of acoustic attenuation characterized by a frequency dependence power law. First we prove existence of a unique solution to this equation with…

Numerical Analysis · Mathematics 2021-03-26 Katherine Baker , Lehel Banjai