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In this paper we apply the boundary elements method (BEM) and the dual reciprocity boundary elements method (DRBEM) for the numerical solution of two-dimensional time-fractional partial differential equations (TFPDEs). The fractional…

Numerical Analysis · Mathematics 2023-05-23 Peyman Alipour

This paper concerns the quantitative step of the medical imaging modality Thermo-acoustic Tomography (TAT). We model the radiation propagation by a system of Maxwell's equations. We show that the index of refraction of light and the…

Analysis of PDEs · Mathematics 2015-06-17 Guillaume Bal , Ting Zhou

We investigate the Helmholtz equation in a two dimensional open waveguide with a thin and high contrast core layer. We develop an asymptotic analysis of the Green function of the problem, and through it we identify and characterize the…

Analysis of PDEs · Mathematics 2025-10-01 Eric Bonnetier , Matias Courdurier , Axel Osses , Faouzi Triki

This work addresses an inverse problem for a semi-discrete parabolic equation, consisting of identifying the right-hand side of the equation from solution measurements at an intermediate time and within a spatial subdomain. We apply this…

Analysis of PDEs · Mathematics 2025-10-10 Rodrigo Lecaros , Juan López-Ríos , Ariel A. Pérez

We show that the properties of the lower part of the spectrum of the Helmholtz equation for an heterogeneous system in a finite region in $d$ dimensions, where the solutions to the homogeneous problems are known, can be systematically…

Mathematical Physics · Physics 2015-12-23 Paolo Amore

A rigorous reduction of the many-body wave scattering problem to solving a linear algebraic system is given bypassing solving the usual system of integral equation. The limiting case of infinitely many small particles embedded into a medium…

Mathematical Physics · Physics 2009-11-13 A. G. Ramm

Exterior inverse problem for the circular means transform (CMT) arises in the intravascular photoacoustic imaging (IVPA), in the intravascular ultrasound imaging (IVUS), as well as in radar and sonar. The reduction of the IPVA to the CMT is…

Analysis of PDEs · Mathematics 2013-08-29 Gaik Ambartsoumian , Leonid Kunyansky

In this work we develop a new numerical approach for recovering a spatially dependent source component in a standard parabolic equation from partial interior measurements. We establish novel conditional Lipschitz stability and H\"{o}lder…

Numerical Analysis · Mathematics 2025-08-22 Tianhao Hu , Xinchi Huang , Bangti Jin , Qimeng Quan , Zhi Zhou

The purpose of this paper is to solve a kind of Riemann-Hilbert boundary value problem for $(\varphi,\psi)$-harmonic functions, which are linked with the use of two orthogonal basis of the Euclidean space $\mathbb{R}^m$. We approach this…

Analysis of PDEs · Mathematics 2020-05-19 José Luis Serrano Ricardo , Ricardo Abreu Blaya , Juan Bory Reyes , Jorge Sánchez Ortiz

In the present paper we describe a method for solving inverse problems for the Helmholtz equation in radially-symmetric domains given multi-frequency data. Our approach is based on the construction of suitable trace formulas which relate…

Numerical Analysis · Mathematics 2023-10-16 Abinand Gopal , Jeremy Hoskins , Vladimir Rokhlin

This paper considers to the problems of diffraction of electromagnetic waves on a half-plane, which has a finite inclusion in the form of a Lipschitz curve. The diffraction problem formulated as boundary value problem for Helmholtz…

Mathematical Physics · Physics 2018-03-06 E. Lipachev

The notion of inertial reference frame is abandoned and I replaced it by a local reference frame on which the fundamental law of mechanics is expressed. The distant interactions of cause and effect are modeled by the propagation of waves…

Fluid Dynamics · Physics 2020-08-10 Jean-Paul Caltagirone

We analyse the internal dynamics of star-forming HII regions and their efficiency in interacting with the ISM. We use GHaFaS (Fabry-Perot) data of the nearby spiral galaxy M83 to perform multiple-Gaussian fitting to the integrated Halpha…

Cosmology and Nongalactic Astrophysics · Physics 2009-09-23 Javier Blasco-Herrera , Kambiz Fathi , John Beckman , Leonel Gutiérrez , Andreas Lundgren , Joan Font , Olivier Hernandez , Claude Carignan

In this paper we discuss the numerical solution on a simple 2D domain of the Helmoltz equation with mixed boundary conditions. The so called radiation problem depends on the wavenumber constant parameter k and it is inspired here by medical…

The 21-cm emission from atomic hydrogen (HI) is one of the most important tracers of the structure and dynamics of the interstellar medium. Thanks to Galactic rotation, the line is Doppler shifted and, assuming a model for the velocity…

Astrophysics of Galaxies · Physics 2023-05-26 Philipp Mertsch , Vo Hong Minh Phan

We study singular 1/2 BPS solutions in M-theory using 11-dimensional superstar solutions. The superstar solutions and their corresponding plane wave limits could give an insight how one may deform the boundary conditions to get singular,…

High Energy Physics - Theory · Physics 2007-05-23 Mohsen Alishahiha , Hossein Yavartanoo

We get a local existence result in $H^s$ with $s>3/2$ for second order quasilinear wave equation with radial initial data in 2+1 dimensions, based on an improvement of Strichartz estimate in the radial case. Moreover, we get the…

Analysis of PDEs · Mathematics 2007-05-23 Chengbo Wang , Daoyuan Fang

We consider the convected Helmholtz equation with a generalized Myers boundary condition (a boundary condition of the second-order) and characterize the set of physical parameters for which the problem is weakly well-posed. The model comes…

Analysis of PDEs · Mathematics 2025-06-26 Nabil Alami , Edward Lucyszyn , Raphaél Pain Dit Hermier , Anna Rozanova-Pierrat

In this paper, we consider the Hessian equations in some exterior domain with prescribed asymptotic behavior at infinity and Dirichlet-Neumann conditions on its interior boundary. We obtain that there exists a unique bounded domain such…

Analysis of PDEs · Mathematics 2024-12-17 Bo Wang , Zhizhang Wang

In this paper, we deal with the problem of determining perfectly insulating regions (cavities) from one boundary measurement in a nonlinear elliptic equation arising from cardiac electrophysiology. Based on the results obtained in [9] we…

Analysis of PDEs · Mathematics 2022-08-09 Elena Beretta , M. Cristina Cerutti , Dario Pierotti , Luca Ratti