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This paper presents a matrix formulation of the scalar laws of radiative transfer. The method applies to coupled mixed boundary condition problems on general domains. Participating media can range from transparent to absorbing, emitting,…

Computational Physics · Physics 2026-05-27 Nikolaj Maack Bielefeld

We study the direct and an inverse source problem for the radiative transfer equation arising in optical molecular imaging. We show that for generic absorption and scattering coefficients, the direct problem is well-posed and the inverse…

Analysis of PDEs · Mathematics 2008-03-31 Plamen Stefanov , Gunther Uhlmann

We consider a fixed angle inverse scattering problem in the presence of a known Riemannian metric. First, assuming a no caustics condition, we study the direct problem by utilizing the progressing wave expansion. Under a symmetry assumption…

Analysis of PDEs · Mathematics 2021-07-21 Shiqi Ma , Mikko Salo

In this paper, we study the Moore-Penrose inverses of differences and products of projectors in a ring with involution. Also, some necessary and sufficient conditions for the existence of such inverses are given, and their expressions are…

Rings and Algebras · Mathematics 2016-02-23 Huihui Zhu , Jianlong Chen , Pedro Patricio

It has been proven that when connecting two infinite semi-cylinders or waveguides with a finite cylinder or resonator at a certain frequency, it is possible to transmit a signal almost completely from one semi-cylinder to another. In this…

Mathematical Physics · Physics 2024-11-26 Andrey L. Delitsyn , Irina K. Troshina

In this article we use the Desargues' theorem and its reciprocal to solve two problems.

General Mathematics · Mathematics 2011-01-13 Florentin Smarandache , Ion Patrascu

The purpose of this report is a study of the algebraic approach possibilities to reconstruct images. This approach is reduced to solution of the large system of linear algebraic equations. We also point out some possible further…

General Physics · Physics 2016-01-01 E. E. Libin , S. V. Chakhlov , D. Trinca

The semiclassical backreaction equations are solved in closed Robertson-Walker spacetimes containing a positive cosmological constant and a conformally coupled massive scalar field. Renormalization of the stress-energy tensor results in…

General Relativity and Quantum Cosmology · Physics 2023-08-23 Leda Gao , Paul R. Anderson , Robert S. Link

Suppose we are given an environment consisting of axis-parallel and diagonal line segments with integer endpoints, each of which may be reflective or non-reflective, with integer endpoints, and an initial position for a light ray passing…

Computational Geometry · Computer Science 2022-06-24 David Eppstein

The inversion in the sphere or Kelvin transformation, which exchanges the radial coordinate for its inverse, is used as a guide to relate distinct electrostatic problems with dual features. The exact solution of some nontrivial problems are…

Classical Physics · Physics 2017-02-01 R. L. P. G. Amaral , O. S. Ventura , N. A. Lemos

Reflectometry is a technique that uses the light reflected by a sample to determine properties of the sample. Interferometric reflectometry uses interference between two beams, one of which is incident on ---and reflected back by--- a…

Optics · Physics 2019-10-10 Alexander Nahmad-Rohen , Wolfgang Langbein

We study an inverse source scattering problem for the Schr\"odinger equation with a quadratic nonlinearity. In general, uniqueness of inverse source problems can not be guaranteed at a fixed energy. Therefore, additional information is…

Analysis of PDEs · Mathematics 2023-03-22 Lei Zhang , Yue Zhao

We present an elementary proof concerning reciprocal transmittances and reflectances. The proof is direct, simple, and valid for the diverse objects that can be absorptive and induce diffraction and scattering, as long as the objects…

We study the inverse problem for the fractional Laplace equation with multiple nonlinear lower order terms. We show that the direct problem is well-posed and the inverse problem is uniquely solvable. More specifically, the unknown…

Analysis of PDEs · Mathematics 2020-09-18 Ru-Yu Lai , Laurel Ohm

This paper deals with the solution of Maxwell's equations to model the electromagnetic fields in the case of a layered earth. The integrals involved in the solution are approximated by means of a novel approach based on the splitting of the…

Numerical Analysis · Mathematics 2023-01-04 Eleonora Denich , Paolo Novati , Stefano Picotti

The inverse problem of amplitude reconstruction on an inclined line based on the values of amplitude or its module as recorded on semi-infinite line orthogonal to the beam propagation direction is considered within the framework of 2D…

Numerical Analysis · Mathematics 2021-05-21 R. M. Feshchenko , I. A. Artyukov , A. V. Vinogradov

The reciprocity principle is that, when an emitted wave gets scattered on an object, the scattering transition amplitude does not change if we interchange the source and the detector - in other words, if incoming waves are interchanged with…

Quantum Physics · Physics 2015-11-19 László Deák , Tamás Fülöp

In what follows we first set the context for inverse scattering in nuclear physics with a brief account of inverse problems in general. We then turn to inverse scattering which involves the S-matrix, which connects the interaction potential…

Nuclear Theory · Physics 2012-05-03 Raymond S. Mackintosh

The increasing interest in compact astrophysical objects (neutron stars, binaries, galactic black holes) has stimulated the search for rigorous methods, which allow a systematic general relativistic description of such objects. This paper…

General Relativity and Quantum Cosmology · Physics 2008-11-26 G. Neugebauer , R. Meinel

We study the energy-critical nonlinear wave equation in the presence of an inverse-square potential in dimensions three and four. In the defocusing case, we prove that arbitrary initial data in the energy space lead to global solutions that…

Analysis of PDEs · Mathematics 2020-06-23 Changxing Miao , Jason Murphy , Jiqiang Zheng