Universiteit Antwerpen

Op 3 februari ontvangt Sem Peelman, student van ons departement, de BIR&D award voor zijn bijdrage in het multidisciplinaire SmartCare project (zie smartcare.be). In het door de UA gelanceerde project verkenden de teams de toepasbaarheid van ijle technieken bij het modelleren van bio-electrische signalen. Een van die ijle technieken werd aan de UA ontwikkeld in de onderzoeksgroep CANT (prof. dr. Annie Cuyt) en inmiddels gepatenteerd.

De award ceremonie wordt voorafgegaan door een perslunch waarop student en promotor het project en de behaalde resultaten toelichten (zie www.birdbelgium.com).

Public defense of the PhD-thesis: “Iterative and multigrid methods for wave problems with complex-valued boundaries”, by Bram Reps.

The defense is public and takes place in aula Jan Fabre (G0.10) of building G, Middelheimlaan 1, 2020 Antwerpen.

Abstract: The ultimate goal of many a research is to develop an efficient solver for wave and scattering problems that are described by the Helmholtz equation defined on infinite domains. With this thesis we contribute our ideas and insights to this rich but still incomplete branch of applied mathematics. Exterior complex scaling is used to enforce outgoing boundary conditions on the truncated numerical domain. In this light, we have developed an innovative multigrid inverted preconditioner for the numerical solution of indefinite Helmholtz problems with Krylov subspace methods, that is based on complex stretched grids. The multigrid method is further stabilized with non-standard smoothing components for the inversion of competitive preconditioners of which the wave number dependency is examined. The ideas are founded on new theoretical results on the spectrum of the Helmholtz operator with a constant wave number that is discretized with complex-valued mesh widths. Numerical results, on the one hand, confirm the analysis and, on the other hand, verify its usefulness for more general heterogeneous two- and three-dimensional Helmholtz models that originate from both acoustics and quantum mechanical break-up problems.

 Meeting on Multi Paradigm Modeling

• Date: Tuesday, December 20th, 2011 - 13:00 - 16:00
• Location: Univeristy of Antwerp - Campus Middelheim - Room G005
• Contact Person: Hans Vangheluwe

Agenda

• Talk by Juan de Lara (UaM, Spain) "Flexible Model-Driven Engineering through Deep Meta-modelling and Genericity"
• Talk by Dennis Wagelaar (VUB) "Towards a general composition semantics for rule-based model transformations"
• Talk by Tom Mens and Romuald Deshayes (UMons) "Modeling the interactive behaviour of 3D objects"

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You are invited to a seminar organized by the Applied Math and Numerical Analysis group.
Friday 28 October: CMI G.017 13h00

Seminar on Oscillatory Integrals and its applications.
The are two speakers.
Title: Numerical Methods for oscillatory Integrals
Speaker: Daan Huybrechs, K.U.Leuven.
Abstract: Oscillatory integrals appear in a wide variety of scientific disciplines. Their numerical evaluation is often a time-consuming part of numerical simulations, due to the perceived need for sampling the integrand at a sufficiently high rate. On the other hand, oscillatory integrals are a classical topic in asymptotic analysis. Results in this field surprisingly indicate that there is no mathematical reason for the need to sample at a rate proportional to the frequency of the integrand. Recent numerical methods exploit the asymptotic behavior of oscillatory integrals and can evaluate highly oscillatory integrals at a fixed cost, independent of the frequency. We review a selection of techniques and discuss their applicability and limitations.
Title: Scattering Calculations in the Oscillator Representation. Speaker: Wim Vanroose, U. Antwerpen.
Abstract: Many physical problems are solved in the oscillator representation, a L^2 basis formed by the eigenstates of the harmonic oscillator. These are based the Hermite and Laguerre orthogonal polynomials for, respectively, 1D and 3D problems. However, often very large basis sets are required and this requires polynomials of very high order which leads to the evaluation of many oscillatory integrals. In the talk we discuss the asymptotic properties of oscillatory integrals that allow us to replaces a large part of the problem with a sparse approximation. Various examples from physics are being discussed.