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On highly oscillatory problems arising in electronic engineering

Marissa Condon, Alfredo Deaño, Arieh Iserles (2009)

ESAIM: Mathematical Modelling and Numerical Analysis

In this paper, we consider linear ordinary differential equations originating in electronic engineering, which exhibit exceedingly rapid oscillation. Moreover, the oscillation model is completely different from the familiar framework of asymptotic analysis of highly oscillatory integrals. Using a Bessel-function identity, we expand the oscillator into asymptotic series, and this allows us to extend Filon-type approach to this setting. The outcome is a time-stepping method that guarantees ...

On the analysis of Bérenger’s perfectly matched layers for Maxwell’s equations

Eliane Bécache, Patrick Joly (2002)

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

In this work, we investigate the Perfectly Matched Layers (PML) introduced by Bérenger [3] for designing efficient numerical absorbing layers in electromagnetism. We make a mathematical analysis of this model, first via a modal analysis with standard Fourier techniques, then via energy techniques. We obtain uniform in time stability results (that make precise some results known in the literature) and state some energy decay results that illustrate the absorbing properties of the model. This last...

On the analysis of Bérenger's Perfectly Matched Layers for Maxwell's equations

Eliane Bécache, Patrick Joly (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

In this work, we investigate the Perfectly Matched Layers (PML) introduced by Bérenger [3] for designing efficient numerical absorbing layers in electromagnetism. We make a mathematical analysis of this model, first via a modal analysis with standard Fourier techniques, then via energy techniques. We obtain uniform in time stability results (that make precise some results known in the literature) and state some energy decay results that illustrate the absorbing properties of the model. This...

On the approximate solution of integro-differential equations arising in oscillating magnetic fields

K. Maleknejad, M. Hadizadeh, M. Attary (2013)

Applications of Mathematics

In this work, we propose the Shannon wavelets approximation for the numerical solution of a class of integro-differential equations which describe the charged particle motion for certain configurations of oscillating magnetic fields. We show that using the Galerkin method and the connection coefficients of the Shannon wavelets, the problem is transformed to an infinite algebraic system, which can be solved by fixing a finite scale of approximation. The error analysis of the method is also investigated....

On the computation of Aden functions

Peter Maličký, Marianna Maličká (1991)

Applications of Mathematics

The paper deals with the computation of Aden functions. It gives estimates of errors for the computation of Aden functions by downward reccurence.

On the computation of Riccati-Bessel functions

Peter Maličký, Marianna Maličká (1990)

Aplikace matematiky

The paper deals with the computation of Riccati-Bessel functions. A modification of Miller method is presented together with estimates of relative errors.

On the curvature and torsion effects in one dimensional waveguides

Guy Bouchitté, M. Luísa Mascarenhas, Luís Trabucho (2007)

ESAIM: Control, Optimisation and Calculus of Variations

We consider the Laplace operator in a thin tube of ℝ 3 with a Dirichlet condition on its boundary. We study asymptotically the spectrum of such an operator as the thickness of the tube's cross section goes to zero. In particular we analyse how the energy levels depend simultaneously on the curvature of the tube's central axis and on the rotation of the cross section with respect to the Frenet frame. The main argument is a Γ-convergence theorem for a suitable sequence of quadratic energies.

On the derivation and mathematical analysis of some quantum–mechanical models accounting for Fokker–Planck type dissipation: Phase space, Schrödinger and hydrodynamic descriptions

José Luis López, Jesús Montejo–Gámez (2013)

Nanoscale Systems: Mathematical Modeling, Theory and Applications

This paper is intended to provide the reader with a review of the authors’ latest results dealing with the modeling of quantum dissipation/diffusion effects at the level of Schrödinger systems, in connection with the corresponding phase space and fluid formulations of such kind of phenomena, especially in what concerns the role of the Fokker–Planck mechanism in the description of open quantum systems and the macroscopic dynamics associated with some viscous hydrodynamic models of Euler and Navier–Stokes...

On the geometry of convex reflectors

Vladimir I. Oliker (2002)

Banach Center Publications

In this paper we consider a special class of convex hypersurfaces in Euclidean space which arise as weak solutions to some inverse problems of recovering reflectors from scattering data. For this class of hypersurfaces we study the notion of the focal function which, while sharing the important convexity property with the classical support function, has the advantage of being exactly the "right tool" for such inverse problems. We also discuss briefly the close analogy between one such inverse problem...

On the Ginzburg-Landau and related equations

Yu N. Ovchinnikov, Israel Michael Sigal (1997/1998)

Séminaire Équations aux dérivées partielles

We describe qualitative behaviour of solutions of the Gross-Pitaevskii equation in 2D in terms of motion of vortices and radiation. To this end we introduce the notion of the intervortex energy. We develop a rather general adiabatic theory of motion of well separated vortices and present the method of effective action which gives a fairly straightforward justification of this theory. Finally we mention briefly two special situations where we are able to obtain rather detailed picture of the vortex...

On the importance of solid deformations in convection-dominated liquid/solid phase change of pure materials

Daniela Mansutti, Edoardo Bucchignani (2011)

Applications of Mathematics

We analyse the effect of the mechanical response of the solid phase during liquid/solid phase change by numerical simulation of a benchmark test based on the well-known and debated experiment of melting of a pure gallium slab counducted by Gau & Viskanta in 1986. The adopted mathematical model includes the description of the melt flow and of the solid phase deformations. Surprisingly the conclusion reached is that, even in this case of pure material, the contribution of the solid phase to the...

On the linear force-free fields in bounded and unbounded three-dimensional domains

Tahar-Zamène Boulmezaoud, Yvon Maday, Tahar Amari (2010)

ESAIM: Mathematical Modelling and Numerical Analysis

Linear Force-free (or Beltrami) fields are three-components divergence-free fields solutions of the equation curlB = αB, where α is a real number. Such fields appear in many branches of physics like astrophysics, fluid mechanics, electromagnetics and plasma physics. In this paper, we deal with some related boundary value problems in multiply-connected bounded domains, in half-cylindrical domains and in exterior domains.

Currently displaying 401 – 420 of 697