Upcoming Events

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Monday, 26.02.2018, 14:00 (WIAS-ESH)
Seminar Laserdynamik
Dr. K. Mora, Universität Paderborn:
Says Newton to Hopf and Hogkin--Huxley: Vibrating! Impacting! Exciting!
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
WIAS Berlin
Wednesday, 28.02.2018, 15:15 (WIAS-ESH)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. M. Egert, Université de Paris-Sud, Frankreich:
How half-order time derivatives help us to better understand parabolic equations
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
In the study of parabolic problems, the prototypes of which are related to the heat operator ∂ t - Δ, an old but often overlooked approach is to decompose the time-derivative into two fractional derivatives of order 1/2. Depending on ones preferences, this can either be considered 'natural' since it brings back the parabolic homogeneity, for instance when the elliptic part is interpreted in the weak sense via a sesquilinear form, or rather 'peculiar' as it introduces non-local operators in the context of local equations.

In this talk I shall touch on some recent results that used half-order time-derivatives in a crucial way, placing an emphasis on my own contributions obtained with several collaborators. This includes improvements of time-regularity for solutions to parabolic systems with measurable coefficients of second as well as fractional order, non-autonomous maximal regularity for the related initial value problem, a new approach to parabolic boundary value problems, and the solution of the parabolic Kato square root problem.

Host
Humboldt-Universität zu Berlin
WIAS Berlin

Thursday, 01.03.2018, 14:00 (WIAS-ESH)
Seminar Numerische Mathematik
Dr. F. Dassi, Politecnico di Milano, Italien:
Recent advancements of the Virtual Element Method in 3D
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
The Virtual Element Method is a novel way to discretize a partial differential equation. It avoids the explicit integration of shape functions and introduces an innovative construction of the stiffness matrix so that it acquires very interesting properties and advantages. One among them is the possibility to apply the VEM to general polygonal/polyhedral domain decomposition, also characterized by non-conforming and non-convex elements.
In this talk we focus on the definition/construction of the Virtual Element functional spaces in three dimensions and how apply this new strategy to set a standard Laplacian problem in 3D.
Finally we test the method to show its robustness with respect to element distortion and the polynomial approximation degree $k$. Then, we move to more involved cases: convection-diffusion-reaction problems with variable coefficients and magnetostatic Maxwell equations.

Host
WIAS Berlin
Thursday, 03.05.2018, 14:00 (WIAS-ESH)
Seminar Numerische Mathematik
Dr. H. Stephan, WIAS Berlin:
One million perrin pseudo primes including a few giants
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
WIAS Berlin