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It is shown that asymmetric waveguides with gain and loss can support a stable propagation of optical beams. This means that the propagation constants of modes of the corresponding complex optical potential are real. A class of such…

Pattern Formation and Solitons · Physics 2015-06-22 Eduard N. Tsoy , Izzat M. Allayarov , Fatkhulla Kh. Abdullaev

Anatomical segmentation of organs in ultrasound images is essential to many clinical applications, particularly for diagnosis and monitoring. Existing deep neural networks require a large amount of labeled data for training in order to…

Image and Video Processing · Electrical Eng. & Systems 2023-08-01 Yordanka Velikova , Mohammad Farid Azampour , Walter Simson , Vanessa Gonzalez Duque , Nassir Navab

In the present study, the authors introduce a geometrically improved model inspired by the mammalian basilar membrane's properties and special vibratory behavior while conducting a parametric investigation. The goal of this model is to…

Dynamical Systems · Mathematics 2024-12-18 Amirhossein Omidi Soroor , Pablo A. Tarazaga

This paper describes the setup of two different solutions for laboratory X-ray microscopy working with geometric magnification. One setup uses thin-film transmission targets with an optimized tungsten-layer thickness and the electron gun…

Instrumentation and Detectors · Physics 2015-06-11 Thomas Ebensperger , Philipp Stahlhut , Frank Nachtrab , Simon Zabler , Randolf Hanke

We numerically analyse extraordinary terahertz transmission properties of an array of rectangular shaped apertures perforated periodically on a thin metal film. The apertures are tapered at different angles to achieve higher field…

Optics · Physics 2016-03-01 Koijam Monika Devi , Amarendra K. Sarma , Gagan Kumar

Stiffener layout optimization of complex surfaces is fulfilled within the framework of topology optimization. A combined parameterization method is developed in two aspects. One is to parameterize the material distribution of the stiffener…

Computational Engineering, Finance, and Science · Computer Science 2022-01-26 Weihong Zhang , Shengqi Feng

Waves in excitable media can be treated by a simple geometric theory. The propagation velocity is assumed known and evolution of wave fronts is determined by elementary physical principles (Fermat's principle, Huygens' principle). Based on…

Pattern Formation and Solitons · Physics 2007-05-23 Kristof Kaly-Kullai

We use the alternating direction method to simulate implicit dynamics. ur spatial discretization uses isogeometric analysis. Namely, we simulate a (hyperbolic) wave propagation problem in which we use tensor-product B-splines in space and…

Numerical Analysis · Mathematics 2019-11-20 Marcin Los , Pouria Behnoudfar , Maciej Paszynski , Victor Manuel Calo

We construct pulse-type approximate solutions to nonlinear hyperbolic equations near diffractive points, allowing arbitrary (even infinite) order of grazing. We show that in low regularity spaces and the high frequency limit, such solutions…

Analysis of PDEs · Mathematics 2026-05-01 Jian Wang , Mark Williams

We propose a quantum algorithm that simulates the propagation of a light field through a weakly inhomogeneous medium. The wave equation in the paraxial approximation in inhomogeneous material takes the form of the Schr\"odinger equation…

Quantum Physics · Physics 2026-04-01 Siavash Davani , Martin Gärttner , Falk Eilenberger

Reconfigurable intelligent metasurfaces have been proposed as an efficient solution for improving wireless telecommunication systems in multiple scattering or reverberating media. Concurrently, topology optimization has been successfully…

Applied Physics · Physics 2023-11-07 Theodosios D. Karamanos , Mathias Fink , Fabrice Lemoult

Linear-parametric optimization, where multiple objectives are combined into a single objective using linear combinations with parameters as coefficients, has numerous links to other fields in optimization and a wide range of application…

Optimization and Control · Mathematics 2025-01-22 Levin Nemesch , Stefan Ruzika , Clemens Thielen , Alina Wittmann

An approximation is elaborated for the paraxial propagation of diffracted beams, with both one- and two-dimensional cross sections, which are released from apertures with sharp boundaries. The approximation applies to any beam under the…

Optics · Physics 2016-06-29 Eitam Luz , Er'el Granot , Boris A. Malomed

The helicity or chirality of scattered light is strongly linked to the dual symmetry of the scatterer. The latter depends on chiral materials or on scatterers which are not superimposable with their mirror image. This inherently yields…

Acoustic wave propagation in a one-dimensional waveguide connected with Helmholtz resonators is studied numerically. Finite amplitude waves and viscous boundary layers are considered. The model consists of two coupled evolution equations: a…

Classical Physics · Physics 2015-06-16 Bruno Lombard , Jean-François Mercier

The paper derives and analyses the (semi-)discrete dispersion relation of the Parareal parallel-in-time integration method. It investigates Parareal's wave propagation characteristics with the aim to better understand what causes the well…

Numerical Analysis · Mathematics 2018-07-02 Daniel Ruprecht

We investigate reduced-order models for acoustic and electromagnetic wave problems in parametrically defined domains. The parameter-to-solution maps are approximated following the so-called Galerkin POD-NN method, which combines the…

Numerical Analysis · Mathematics 2024-06-21 Philipp Weder , Mariella Kast , Fernando Henríquez , Jan S. Hesthaven

An elastic ideal 2D propagation medium, i.e., a membrane, can be simulated by models discretizing the wave equation on the time-space grid (finite difference methods), or locally discretizing the solution of the wave equation (waveguide…

Sound · Computer Science 2024-09-21 Federico Fontana , Davide Rocchesso

The knowledge of receiver beam shapes is essential for accurate radio interferometric imaging. Traditionally, this information is obtained by holographic techniques or by numerical simulation. However, such methods are not feasible for an…

Instrumentation and Methods for Astrophysics · Physics 2013-07-19 Sarod Yatawatta

In this paper we introduce methods for electromagnetic wave propagation, based on splines and on T-splines. We define spline spaces which form a De Rham complex and, following the isogeometric paradigm, we map them on domains which are…

Numerical Analysis · Mathematics 2012-09-11 A. Buffa , G. Sangalli , R. Vazquez