Search results for "Maxwellin yhtälöt"

How much is enough? : The convergence of finite sample scattering properties to those of infinite media

2021

We study the scattering properties of a cloud of particles. The particles are spherical, close to the incident wavelength in size, have a high albedo, and are randomly packed to 20% volume density. We show, using both numerically exact methods for solving the Maxwell equations and radiative-transfer-approximation methods, that the scattering properties of the cloud converge after about ten million particles in the system. After that, the backward-scattered properties of the system should estimate the properties of a macroscopic, practically infinite system. (C) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.o…

Partial data inverse problems for Maxwell equations via Carleman estimates

2015

In this article we consider an inverse boundary value problem for the time-harmonic Maxwell equations. We show that the electromagnetic material parameters are determined by boundary measurements where part of the boundary data is measured on a possibly very small set. This is an extension of earlier scalar results of Bukhgeim-Uhlmann and Kenig-Sj\"ostrand-Uhlmann to the Maxwell system. The main contribution is to show that the Carleman estimate approach to scalar partial data inverse problems introduced in those works can be carried over to the Maxwell system.

Electromagnetic wave propagation in non-homogeneous waveguides

2015

We investigate an electromagnetic waveguide, having several cylindrical ends. The waveguide is assumed to be empty and to have a perfectly conductive boundary. We study the electromagnetic field, excited in the waveguide in the presence of charges and currents. The field can be described as a solution of the stationary Maxwell system with conductive boundary conditions and “intrinsic” radiation conditions at infinity. We prove the problem to be well-posed. Electromagnetic waves propagation in the waveguide can be described by means of a scattering matrix. We introduce such a matrix for all values of the spectral parameter k in the waveguide continuous spectrum and study its properties. Moreove…

On a numerical solution of the Maxwell equations by discrete exterior calculus

2014

Sähkömagneettisen sironnan numeerinen simulointi

2004

The nonstationary Maxwell system in domains with edges and conical points

2005

Sergey Matyukevich on väitöskirjassaan tutkinut Maxwell-yhtälöä alueilla, joilla on kartiomaisia kärkiä ja teräviä särmiä. Erityisen huomion kohteena tutkimuksessa oli tutkia yhtälön ratkaisujen käyttäytymistä lähellä ns. singulaaripisteitä, joita epäsileät reunat aiheuttavat. Tutkimuksessa Matyukevich on johtanut ratkaisuille eksplisiittisiä, asymptoottisia laajennuksia alueen kartiomaisten kärkien ja terävien särmien ympäristössä.Tutkimuksen tuloksilla on merkitystä siinä, että niitä voidaan soveltaa useiden ei-stationaaristen sähkömagnetiikan yhtälöiden matemaattisessa ja numeerisessa analysoinnissa epäsileillä alueilla. We study the nonstationary Maxwell system in domains with conical p…