Veranstaltungen

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18. – 22. März 2019 (ZIB-SEM)
Workshop/Konferenz: New Directions in Stochastic Analysis: Rough Paths, SPDEs and Related Topics
mehr ... Veranstaltungsort
Zuse-Zentrum für Informationstechnik (ZIB), Takustr. 7, 14195 Berlin, Seminarraum

Veranstalter
Technische Universität Berlin
WIAS Berlin
Universität Potsdam
Freie Universität Berlin
DFG Research Unit 2402
European Research Council
20. – 22. März 2019 (IAP)
Workshop/Konferenz: Leibniz MMS Days 2019
mehr ... Veranstaltungsort
Leibniz-Institute of Atmospheric Physics, Schlossstr. 6, 04318 Kühlungsborn, Germany

Veranstalter
WIAS Berlin
Dienstag, 26.03.2019, 15:00 Uhr (WIAS-ESH)
Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Dr. V. Avanesov, WIAS Berlin:
Nonparametric change point detection in regression
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
WIAS Berlin
Mittwoch, 27.03.2019, 10:30 Uhr (WIAS-406)
Seminar Interacting Random Systems
Dr. G. L. Torrisi, Istituto per le Applicazioni del Calcolo “Mauro Picone” (C.N.R), Italien:
The Clark-Ocone formula for point processes
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Abstrakt
Clark-Ocone formulas are powerful results in stochastic analysis with a variety of applications. In the talk we provide the Clark-Ocone formula for square-integrable functionals of point processes with stochastic intensity. Then we present two applications of the formula: the Poincare' inequality and a deviation bound for those functionals. Our results generalize the corresponding ones on the Poisson space

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Seminar Interacting Random Systems

Veranstalter
WIAS Berlin
Dienstag, 23.04.2019, 14:00 Uhr (WIAS-406)
Seminar Materialmodellierung
M. Milicevic, Albert-Ludwigs-Universität Freiburg:
The alternating direction method of multipliers with variable step sizes for the iterative solution of nonsmooth minimization problems and application to BV-damage evolution
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Abstrakt
The alternating direction method of multipliers (ADMM) is a flexible numerical method to solve a large class of convex minimization problems. Its most significant properties are the unconditional convergence with respect to the involved step size and the direct applicability. However, the performance critically depends on the choice of the step size. We propose an automated step size adjustment that relies on the monotonicity of the residual to accelerate the ADMM. Numerical experiments show a remarkable improvement over the standard ADMM with fixed step sizes. The ADMM with variable step sizes is then applied to a model for rate-independent, total variation regularized damage processes. The total variation regularization of the damage variable leads to sharp transitions of damaged to undamaged areas in the material. The results are compared to an H1-regularization of the damage and the simulations reveal that, indeed, for the total variation regularization sharp transitions can be observed whereas for the H1-regularization the interface is smeared out.

Veranstalter
WIAS Berlin
Freitag, 17.05.2019, 14:00 Uhr (WIAS-ESH)
Seminar Numerische Mathematik
Prof. P. Berg, University of Alberta , Kanada:
Energy conversion in electrokinetic flow through charged and viscoelastic nanochannels
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
The flow of ions and water through viscoelastic, nanoscopic domains forms the basis for many processes in biological materials. Surprisingly, such systems have rarely been explored for nanofluidic transport in artificial channels of technological applications such as energy harvesting, water desalination or DNA purification.
This talk explores the nonlinear coupling between wall deformation and quasi 1-D electrokinetic transport in a nanochannel with charged walls. Within the framework of nonequilibrium thermodynamics, formulae are derived for the electrokinetic transport parameters in terms of Onsager phenomenological coefficients and, subsequently, for energy conversion efficiencies. Results confirm that Onsager's reciprocity principle holds for rigid channels but breaks down in the 1-D formulation when the channel is deformed due to the introduction of a ”fictitious” diffusion term of counter-ions. Furthermore, the model predicts a reduced efficiency of electrokinetic energy harvesting for channels with soft, deformable walls.
This research is conducted in collaboration with Michael Eikerling and Mpumelelo Matse.

Veranstalter
WIAS Berlin
Mittwoch, 22.05.2019, 15:15 Uhr (WIAS-ESH)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. P. Colli, Università di Pavia, Italien:
Well-posedness, regularity and asymptotic analyses for a fractional phase field system
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
Mittwoch, 29.05.2019, 15:00 Uhr (WIAS-ESH)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. P. Tolksdorf, Université Paris-Est - Créteil Val-de-Marne, Frankreich:
On the Lp-theory for second-order elliptic operators in divergence-form with complex coefficients (Part 1)
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
Given a complex, elliptic coefficient function we investigate for which values of p the corresponding second-order divergence form operator, complemented with Dirichlet, Neumann or mixed boundary conditions, generates a strongly continuous semigroup on Lp(Ω). Additional properties like analyticity of the semigroup, H-calculus and maximal regularity are also discussed. Finally we prove a perturbation result for real coefficients that gives the whole range of p's for small imaginary parts of the coefficients. Our results are based on the recent notion of p-ellipticity, reverse Hölder inequalities and Gaussian estimates for the real coefficients.

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Berliner Oberseminar “Nichtlineare partielle Differentialgleichungen" (Langenbach-Seminar)

Veranstalter
WIAS Berlin
Humboldt-Universität zu Berlin
Mittwoch, 05.06.2019, 15:00 Uhr (WIAS-ESH)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. P. Tolksdorf, Université Paris-Est - Créteil Val-de-Marne, Frankreich:
On the Lp-theory for second-order elliptic operators in divergence-form with complex coefficients (Part 2)
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
Given a complex, elliptic coefficient function we investigate for which values of p the corresponding second-order divergence form operator, complemented with Dirichlet, Neumann or mixed boundary conditions, generates a strongly continuous semigroup on Lp(Ω). Additional properties like analyticity of the semigroup, H-calculus and maximal regularity are also discussed. Finally we prove a perturbation result for real coefficients that gives the whole range of p's for small imaginary parts of the coefficients. Our results are based on the recent notion of p-ellipticity, reverse Hölder inequalities and Gaussian estimates for the real coefficients.

Weitere Informationen
Berliner Oberseminar “Nichtlineare partielle Differentialgleichungen" (Langenbach-Seminar)

Veranstalter
WIAS Berlin
Humboldt-Universität zu Berlin
9. – 13. September 2019 (WIAS-ESH)
Workshop/Konferenz: PDE 2019: Partial Differential Equations in Fluids and Solids
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
This workshop fuses expertise on the analysis of PDEs in solids, fluid dynamics, complex fluids, and interaction of fluids with solid structure. Its goal is to create new synergies among these fields in order to advance analytical methods for current research related to systems with bulk-interface interaction, geometrically nonlinear materials, and fluid-structure interaction. This concerns, e. g., Lagrangian and Eulerian descriptions, free boundaries and moving domains, and variational approaches via energy/entropy methods.

Veranstalter
WIAS Berlin
18. – 20. September 2019 (WIAS-ESH)
Workshop/Konferenz: Optical Solitons and Frequency Comb Generation
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
WIAS Berlin