Upcoming Events

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Thursday, 20.06.2024, 10:00 (WIAS-ESH)
MATh.en.JEANS
Julia Hörrmann, WIAS Berlin:
Punktprozesse und Voronoi-Mosaike oder die beste Lage für eine neue Eisdiele
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
WIAS Berlin
Thursday, 20.06.2024, 14:00 (WIAS-ESH)
MATh.en.JEANS
Helia Shafigh, WIAS Berlin:
Überlebenswahrscheinlichkeit eines Hasen unter Wölfen
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
WIAS Berlin
Thursday, 20.06.2024, 14:00 (WIAS-ESH)
MATh.en.JEANS
Helia Shafigh, WIAS Berlin:
Überlebenswahrscheinlichkeit eines Hasen unter Wölfen
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
WIAS Berlin
Wednesday, 26.06.2024, 09:00 (TUB HE101)
MATh.en.JEANS
Schüler:innen-Konferenz: MATh.en.JEANS
more ... Location
Technische Universität, Straße des 17. Juni 136, 10623 Berlin, HE101

Abstract
https://wias-berlin.de/people/kern/mejkonferenz24/researchers.jsp

Host
WIAS Berlin
Wednesday, 26.06.2024, 14:00 (WIAS-Library)
Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations / Mathematical Optimization
Antonia Topalovic, Humboldt-Universität zu Berlin:
Model Predictive Control for Generalized Nash Equilibrium Problems
more ... Location
Weierstraß-Institut, Hausvogteiplatz 5-7, 10117 Berlin, R411

Abstract
We study model predictive control (MPC) schemes for non-cooperative dynamic games. The dynamic games are modelled as jointly convex generalized Nash equilibrium problems (GNEP) governed by a jointly controlled linear time-discrete dynamics. We are particularly interested in the asymptotic stability of the resulting closed-loop dynamics. To this end, we introduce a family of auxiliary problems, $alpha$-Quasi-GNEPs, which approximate the original GNEPs. For MPC schemes based on $alpha$-Quasi-GNEPs, stability guarantees can be derived if stabilizing end-constraints are enforced. This analysis is based on showing that the underlying optimal-value function is a Lyapunov function for the closed-loop. Passing to a limit, we identify a suitable Lyapunov function for MPC schemes based on the original GNEPs.

Further Informations
Joint Research Seminar on Nonsmooth Variational Problems and Operator Equations

Host
WIAS Berlin
Wednesday, 26.06.2024, 16:15 (WIAS-ESH)
Berliner Kolloquium Wahrscheinlichkeitstheorie
Benjamin Jourdain, École des Ponts ParisTech:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
Humboldt-Universität zu Berlin
Technische Universität Berlin
WIAS Berlin
Wednesday, 26.06.2024, 17:15 (WIAS-ESH)
Berliner Kolloquium Wahrscheinlichkeitstheorie
Noemi Kurt, Goethe University Frankfurt:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
Humboldt-Universität zu Berlin
Technische Universität Berlin
WIAS Berlin
July 1, 2024 (WIAS-ESH)
Workshop/Konferenz: Developments in Computational Finance - Honoring John Schoenmakers on the occasion of his retirement
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
WIAS Berlin
Tuesday, 02.07.2024, 10:15 (WIAS-406)
Seminar Nichtlineare Optimierung und Inverse Probleme
Prof. Dr. Stefan Metzger, Friedrich-Alexander-Universität Erlangen-Nürnberg:
An augmented SAV scheme for the stochastic Allen-Cahn equation
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Abstract
The scalar auxiliary variable (SAV) method was originally introduced in [Shen, Xu, Yang, J. Comput. Phys., 2018] for the discretization of deterministic gradient flows. By introducing an additional scalar variable, they were able to formulate linear numerical schemes that are still unconditionally stable with respect to a modified energy. This talk addresses the application of the SAV method to nonlinear stochastic partial differential equations with multiplicative noise. Using the stochastic Allen-Cahn equation as a prototype, we motivate why a straightforward application of the SAV method will not provide satisfactory results and present an augmented SAV method that remedies the shortcomings and allows for a rigorous convergence proof. Using a discrete version of the energy estimate as a starting point, we are able to show convergence towards pathwise unique martingale solutions by applying Jakubowski's generalization of Skorokhod's theorem. Convergence towards (stochastically) strong solutions can then be shown using a generalization of the Gyöngy-Krylov characterization of convergence in probability. We conclude by presenting numerical simulations which underline the practicality of the scheme and the importance of the introduced augmentation.

Host
WIAS Berlin
Wednesday, 03.07.2024, 14:14 (WIAS-ESH)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Andreas Vikelis, Universität Wien, Österreich:
Measure-valued solutions for non-associative finite plasticity
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
The variational treatment of evolutionary nonassociative elasto-plasticity at finite strains remains unexplored. In this direction, following the concept of energetic solutions, we present an existence result for measure-valued solutions of the quasistatic evolution problem which are stable and balance the energy. In particular, we apply a modification of the standard timediscretization scheme, considering Young measures generated by piecewise constant interpolants of time-discrete solutions of a properly defined minimization problem. A key point in our analysis is the limit passage in the dissipation. The later calls for time-continuity properties of the stresses which are not expected in the quasistatic framework. To overcome this obstacle we introduce a regularization of the generalized stress in the definitionof our energetic solutions. Joint work with Ulisse Stefanelli.

Further Informations
Oberseminar “Nichtlineare Partielle Differentialgleichungen” (Langenbach Seminar)

Host
Humboldt-Universität zu Berlin
WIAS Berlin
Thursday, 04.07.2024, 15:00 (WIAS-406)
Seminar Materialmodellierung
Dr. Jörg Weber, Universität Wien, Österreich:
Axisymmetric capillary water waves with vorticity and swirl
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Abstract
While the research on axisymmetric capillary water waves has a long history, surprisingly little has been done when one wants to allow for vorticity (local spinning) and swirl (angular momentum). After introducing the problem and presenting a well-known formulation in terms of the Stokes stream function, we will explain the main analytical ingredients in order to rigorously construct travelling wave solutions with a free boundary. Then, two solution curves are constructed: First, we start at perfectly cylindrical jets, where we derive the dispersion relation and investigate it in detail in certain cases. Also, we will point out inherent connections to the famous Rayleigh instability observed in everyday life, e.g. when a tap drips. Second, we start at static configurations with constant mean curvature surfaces, so-called unduloids. There, as an interesting interplay between water waves, geometry, and elliptic integrals, we show rigorously that to any such configuration there connects a curve of non-static configurations, which confirms previous numerical observations. The talk is based on joint work with André Erhardt (WIAS), Anna-Mariya Otsetova (Aalto), and Erik Wahlén (Lund).

Further Informations
Seminar “Materialmodellierung”

Host
WIAS Berlin
Wednesday, 10.07.2024, 14:15 (WIAS-ESH)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Caroline Lasser, Technische Universität München:
Variational Gaussian approximation for quantum dynamics
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
The talk considers the time-dependent Schrödinger equation with smooth magnetic and electric potentials in semiclassical scaling. We analyse nonlinearly parametrized approximations by single Gaussian wave packets via the Dirac--Frenkel variational principle. We derive ordinary differential equations of motion for the parameters of the variational solution. We present L2-error bounds and unexpectedly accurate observable error bounds. This is joint work with S. Burkhard, B. Dörich, and M. Hochbruck.

Host
Humboldt-Universität zu Berlin
WIAS Berlin
Wednesday, 10.07.2024, 16:15 (WIAS-ESH)
Berliner Kolloquium Wahrscheinlichkeitstheorie
Dan Crisan, Imperial College London:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
Humboldt-Universität zu Berlin
Technische Universität Berlin
WIAS Berlin
Wednesday, 10.07.2024, 17:15 (WIAS-ESH)
Berliner Kolloquium Wahrscheinlichkeitstheorie
Jiniao Qiu, U of Calgary:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
Humboldt-Universität zu Berlin
Technische Universität Berlin
WIAS Berlin
July 11, 2024 (WIAS-ESH)
Workshop/Konferenz: Second NFDI Berlin-Brandenburg network meeting: Ontologies and Knowledge Graphs
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract

The NFDI_BB meetings aim at setting up a network of all the NFDI consortia located in the Berlin-Brandenburg area. At the successful kickoff meeting last October, the topic Ontologies and Knowledge Graphs was identified as a central task overarching the consortia, so that we will now dedicate ourselves to this topic. Particular focus will be on potential cooperation between the projects from consortia in different disciplines.
During the morning session, the topic Ontologies and Knowledge Graphs will be presented in connection with the activities of the NFDI in several talks. In the afternoon session, we will continue with short presentations on ontology concepts of the individual NFDI consortia. These will then be further explored in interactive discussion formats.
 
Confirmed speakers for the morning session:
 
Lozana Rossanova, TIB (German National Library of Science and Technology), KGI4NFDI, NFDI4Culture
Daniel Mietchen, FIZ Karlsruhe (Leibniz Institute for Information Infrastructure), MaRDI
Olaf Simons, Martin Luther University Halle-Wittenberg, FactGrid, NFDI4Memory
 
Confirmed presenters for the afternoon session:
 
Rolf Krahl, HZB (Helmholtz Centre for Materials and Energy), DAPHNE4NFDI
Frank von Hagel, Berlin State Museums, NFDI4Objects
Sabine von Mering, Natural History Museum, NFDI4Biodiversity
Sonja Schimmler, FOKUS (Fraunhofer Institute for Open Communication Systems), Technical University of Berlin, NFDI4DataScience, Base4NFDI, NFDI4Cat


Host
WIAS Berlin
Monday, 15.07.2024, 10:00 (Berlin Mitte)
MATH+ Thematic Einstein Semester on “Mathematics for Quantum Technologies”
Prof. Ulf Leonhardt, Weizmann Institute of Science, Israel:
First advanced lecture of the series “Forces of the quantum vacuum” .
more ... Location
Berlin Mitte

Abstract
Topic: Setting the scene
Quantization of the electromagnetic field in media and in space-time
Normal modes and harmomic oscillators
Zero-point energy
Casimir's cavity: 1D case, zeta-function renormalization
Casimir's cavity: 3D case, Casimir's renormalization

Host
WIAS Berlin
Einstein Foundation Berlin
Tuesday, 16.07.2024, 10:00 (Berlin Mitte)
MATH+ Thematic Einstein Semester on “Mathematics for Quantum Technologies”
Prof. Ulf Leonhardt, Weizmann Institute of Science, Israel:
Second advanced lecture of the series “Forces of the quantum vacuum” .
more ... Location
Berlin Mitte

Abstract
Topic: Lifshitz theory
The need for a theory in dispersive and dissipative media
Point-splitting method
Fluctuation-dissipation theorem
Kubo-Martin-Schwinger relation
Lifshitz formula in planar, piece-wise homogenous media

Host
WIAS Berlin
Einstein Foundation Berlin
Thursday, 18.07.2024, 10:00 (Berlin Mitte)
MATH+ Thematic Einstein Semester on “Mathematics for Quantum Technologies”
Prof. Ulf Leonhardt, Weizmann Institute of Science, Israel:
Third advanced lecture of the series “Forces of the quantum vacuum” .
more ... Location
Berlin Mitte

Abstract
Topic: Applications
Imaginary frequencies for capturing the broad band of quantum forces
Thermal Casimir effect
Perfectly conducting cavity
Magnetic mirror and Casimir repulsion
Permittivity hierarchy and repulsive Casimir forces
Negative refraction and quantum levitation
Engineering in the imaginary part of the spectrum


Host
WIAS Berlin
Einstein Foundation Berlin
Thursday, 18.07.2024, 15:00 (WIAS-406)
Seminar Materialmodellierung
Prof. Dr. Jan Giesselmann, Technische Universität Darmstadt:
A posteriori error estimates for systems of hyperbolic conservation laws modeling compressible flows
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Abstract
Hyperbolic conservation laws are a class of PDEs that have many applications, most notably in compressible fluid flows when viscosity is neglected. While these equations are successfully used by engineers in simulations, there are many open questions regarding their mathematical study. These are mostly driven by to the non-uniqueness of entropy solutions in multiple space dimensions but even in one space dimensions stability of solutions is challenging if one is to go beyond initial data that are small in BV.
The challenges in the mathematical analysis have lead to a situation where a variety of sophisticated numerical schemes exists and is successfully used in practice but the mathematical foundations of these methods are not as substantial as one would hope. This issue has been addressed by several authors in recent years and we plan plan to present what has been achieved in the field of a posteriori error estimates, i.e. explicit bounds for the error of the numerical solution that can be computed from the numerical solution.
A fundamental building block of a posteriori error estimates are stability theories that allow to relate certain norms of residuals, i.e. quantities measuring by how much an approximate solution fails to satisfy the PDE, to certain norms of the error, i.e. the difference between numerical and exact solution. Examples of such stability theories include the classical relative entropy framework, the theory of shifts developed by Vasseur and coworkers and recent results by Bressan and coworkers.
We will describe these stability results and discuss how they have been used to derive a posteriori error estimates for hyperbolic conservation laws.

Further Informations
Seminar Materialmodellierung

Host
WIAS Berlin
Friday, 19.07.2024, 10:00 (Berlin Mitte)
MATH+ Thematic Einstein Semester on “Mathematics for Quantum Technologies”
Prof. Ulf Leonhardt, Weizmann Institute of Science, Israel:
Fourth advanced lecture of the series “Forces of the quantum vacuum” .
more ... Location
Berlin Mitte

Abstract
Topic: Outlook
The quantum vacuum seen by accelerated observers (relativistic acceleration, Rindler coordinates, Unruh effect)
Entanglement in the quantum vacuum
Classical analogue of the Unruh effect
The case for a Casimir cosmology

Host
WIAS Berlin
Einstein Foundation Berlin
Wednesday, 04.09.2024, 11:30 (WIAS-405-406)
Seminar Interacting Random Systems
Martijn Gösgens, TU Eindhoven:
tba
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406

Abstract
tba

Further Informations
Seminar Interacting Random Systems (Hybrid Event)

Host
WIAS Berlin