Veranstaltungen
- 11. November 2026 (WIAS-406)
- Workshop/Konferenz: Mathematical Modeling and Simulation in (Electro)Chemistry - FHI meets WIAS
mehr ... Veranstaltungsort
Weierstraß-Institut, Anton-Wilhelm-Amo-Str. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)
Abstrakt
The aim of this joint exploratory workshop is to explore possible areas of possible collaboration in mathematical modeling, simulation, optimzation in the context or research for in chemical and electrochemical systems.
Programm:
Multiscale/Overview
9:00 Begrüßung: Fuhrmann, Landstorfer, Reuter
9:05 Dirk Peschka: Numerical simulations and methods for continuum mechanics at WIAS
9:35 Karsten Reuter: Multiscale Modeling and AI in Materials, Energy and Catalysis
10:05 Hendrik Heenen: Machine-Learned Interatomic Potentials for Accelerated Sampling of Operando Catalysts
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10:25 coffee break
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Semiconductors, Light Matter, etc.
11:00 Christian Carbogno: Beyond Ion Dynamics: Efficient Charge Transport Simulations Including Electrons at Battery Scales
11:30 Markus Kantner: Modeling and Simulation of Semiconductor Devices at WIAS: Quantum and Optoelectronics
12:00 Matthias Kick: Light matter interaction from first principles
12:20 Patricio Farrell: Semiconductor Device Applications at WIAS
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12:40 Lunch break
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Electrochemistry
14:00 Manuel Landstorfer: Modeling and Simulation of Electrochemical Systems at WIAS: From Fundamentals to Batteries
14:30 Vanessa Jane Bukas: Questions of Selectivity in Electrocatalysis
15:00 Nico Hörmann: The Butler-Volmer equation and the interfacial dielectric constant: Insights from atomistic simulations at applied potential
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15:20 coffee break
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15:50 Matthias Liero: Variational Methods for Multiscale Problems
16:10 Willem van Zuijlen: Interface growth in a random obstacle field
16:30 Gianmarco Ducci: Kinetic Model Identification via Sparse Symbolic Regression
16:50 Martin Eigel: Scientific Machine Learning for PDEs and Inverse Problems
Veranstalter
Fritz Haber Institute of the Max Planck Society
WIAS Berlin
- Mittwoch, 11.11.2026, 10:00 Uhr (WIAS-ESH)
- Forschungsseminar Mathematische Statistik
Prof. Dr. Simon Weißmann, Universität Mannheim:
Stochastic optimization and regularization for inverse problems
mehr ... Veranstaltungsort
Weierstraß-Institut, Anton-Wilhelm-Amo-Str. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
In this talk, I will investigate two perspectives on the interaction between regularization and stochastic optimization. In the first part, I will present stochastic gradient methods with decaying Tikhonov regularization and show that a suitably balanced vanishing regularization schedule can stabilize the optimization dynamics while preserving convergence to a solution of the original unregularized problem. In the second part, I will turn to data-driven variational regularization, formulated as a stochastic bilevel optimization problem. In this setting, each upper-level evaluation requires a computationally expensive and typically inexact lower-level solve. This naturally motivates the use of multilevel Monte Carlo methods, whose efficiency depends critically on the coupling between successive lower-level approximations.
Weitere Informationen
Dieser Vortrag findet auch via Zoom statt: https://hu-berlin.zoom-x.de/j/65177102181?pwd=nUMtJOkzDx8xyWzPFezeHh0NEIQUv3.1, Meeting-ID 651 7710 2181, Kenncode: 536200
Veranstalter
Humboldt-Universität zu Berlin
Universität Potsdam
WIAS Berlin
- Donnerstag, 12.11.2026, 10:30 Uhr (WIAS-Library)
- Software and Data Seminar
Christian Merdon; Patrick Jaap; Jürgen Fuhrmann:
Introduction to the WIAS-PDELib Julia ecosystem
mehr ... Veranstaltungsort
Weierstraß-Institut, Hausvogteiplatz 5-7, 10117 Berlin, R411
Abstrakt
This seminar presents WIAS-PDELib, an ecosystem of open-source Julia packages developed in our institute for the solution of partial differential equations (PDEs). The ecosystem covers a range of numerical methods, including finite volume and finite element approaches, through packages such as VoronoiFVM.jl and ExtendableFEM.jl, together with supporting tools for grid generations, sparse matrix assembly, and visualization. Join us for an introduction to the main packages, their capabilities, and how they can be used to tackle a variety of PDE-based problems.
Veranstalter
WIAS Berlin
- Mittwoch, 18.11.2026, 10:00 Uhr (WIAS-ESH)
- Forschungsseminar Mathematische Statistik
Prof. Dr. Botond Szabo, Bocconi University, Italy:
Robust Gaussian process regression: Posterior contraction
mehr ... Veranstaltungsort
Weierstraß-Institut, Anton-Wilhelm-Amo-Str. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
Gaussian processes form a popular and flexible class of prior distributions with principled uncertainty quantification, but the Gaussian likelihood on which they rely makes them highly sensitive to outliers and contaminated observations. We study Gaussian process regression when among the $n$ observations, $m$ of these are possibly contaminated. A generic framework to obtain posterior contraction rates in this setting is considered, from a frequentist perspective as the sample size $n$ and the number of corrupted observations $m$ grow. We adopt a generalised Bayes approach in which the log--likelihood is replaced by a robustified version; we discuss various choices thereof, such as one recently proposed by Altamirano et al. (2024) that preserves conjugacy. We investigate the minimax rate of estimation under adversarial contamination in terms of the Sobolev smoothness $be$ of the regression function and $m$. The question of building adaptive procedures to both $be$ and $m$ is investigated, and we show that a polynomial loss for adaptation must be paid in general. We instantiate our results for Matérn Gaussian process and deep ReLU network priors. Numerical experiments for existing and new robust algorithms are provided, illustrating the practical applicability of our results.
Weitere Informationen
Dieser Vortrag findet auch via Zoom statt: https://hu-berlin.zoom-x.de/j/65177102181?pwd=nUMtJOkzDx8xyWzPFezeHh0NEIQUv3.1, Meeting-ID 651 7710 2181, Kenncode: 536200
Veranstalter
Humboldt-Universität zu Berlin
Universität Potsdam
WIAS Berlin
- Mittwoch, 18.11.2026, 14:15 Uhr (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Gianna Götzmann, Universität Augsburg:
Perturbed minimizing movements of time-dependent functionals on metric spaces
mehr ... Veranstaltungsort
Weierstraß-Institut, Anton-Wilhelm-Amo-Str. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
Minimizing movement schemes are a fundamental tool for approximating evolution equations that have a gradient-flow structure with respect to an energy. Motivated by homogenization problems involving, for instance, geometries that evolve in time, we consider Gamma-converging perturbations of time-dependent driving energies. We study the convergence of the corresponding minimizing movement scheme and provide sufficient conditions under which limits of the scheme are (time-dependent) curves of maximal slope for the limit energy. We further exhibit examples showing that, in general, such a stability property may fail, with the limit motion depending on the relation between the time-discretization parameter τ and the perturbation parameter ϵ. This is joint work with Jan-Frederik Pietschmann and Antonio Tribuzio.
Weitere Informationen
Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
- Mittwoch, 25.11.2026, 11:30 Uhr (WIAS-406)
- Seminar Interacting Random Systems
Ulrik Thinggaard Hansen, Karlsruhe Institute of Technology:
Universality of the Large-Scale Geometry for Planar Critical Random-Cluster Models
mehr ... Veranstaltungsort
Weierstraß-Institut, Anton-Wilhelm-Amo-Str. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)
Abstrakt
Conformal invariance of general critical planar lattice models was conjectured by Polyakov in the 70s. Using the (non-rigorous) renormalisation group flow, one may predict that any scaling limit of such a model must be rotationally invariant. Since any such limit must also be translation and scale invariant, the argument goes that it will also be invariant under the action of the group of transformations which are locally compositions of these three types of transformations. This is exactly the conformal group, which, in the planar case, is infinite-dimensional and therefore, particularly rich as a symmetry group. Another conjecture of theoretical physics going back to Griffiths and Kadanoff is that of universality: That the scaling limits of various models with different microscopic details, e.g. the graphs on which they are defined, turn out to be the same across so-called universality classes. During the last 25 years, the first conjecture has received immense attention from the probabilistic community after Schramm's introduction of the SLE. In this talk, however, we shall turn our attention to the second question. Building on work by Duminil-Copin, Kozlowski, Krachun, Manolescu and Oulamara, we prove that the critical random-cluster models each satisfy a universality property across a large class of planar graphs including the hexagonal and triangular lattices. A consequence thereof will be that any scaling limit in one of these universality classes is rotationally invariant and thus, this may also be thought of as a stepping stone towards proving conformal invariance for all critical random-cluster models. Based on joint work with Ioan Manolescu.
Veranstalter
Humboldt-Universität zu Berlin
Technische Universität Berlin
WIAS Berlin
International Research Training Group 2544
- Mittwoch, 02.12.2026, 11:30 Uhr (WIAS-406)
- Seminar Interacting Random Systems
Vinicio Rodrigues Moreira, UFMG Brazil:
tba
mehr ... Veranstaltungsort
Weierstraß-Institut, Anton-Wilhelm-Amo-Str. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)
Abstrakt
tba
Weitere Informationen
Seminar Interactin Random Systems
Veranstalter
WIAS Berlin
- Mittwoch, 09.12.2026, 14:15 Uhr (WIAS-ESH)
- Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Dr. Kathrin Hellmuth, California Institute of Technology, USA:
Connecting models with data: Inverse problems, their well-posedness and computational techniques
mehr ... Veranstaltungsort
Weierstraß-Institut, Anton-Wilhelm-Amo-Str. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
PDEs model real world systems and build the basis of many downstream applications in optimization, control or uncertainty quantification. To ensure alignment, non-observable model parameters are identified that reconstruct observed data from the real system. The quality of this model fitting procedure depends highly on a-priori knowledge and the quality of data. In this talk we look at how these interact, and present three results in this realm and an outlook on ongoing work. A theoretical study exhibits identifiability of the turning coefficient in a run-and-tumble model for bacterial chemotaxis. Reconstructing this microscopic quantity from experiments that only see the macroscopic bacteria density poses a challenge that we overcome by a delicate construction of an experimental data collection strategy. Second, we propose a new perspective and methodology for experimental design when no such construction is available. Relaxing the search from an optimal to a sufficient design allows us to down-sample experiments according to their sensitivity, an idea borrowed from randomized linear algebra. This keeps the parameter identifiable with high probability. Third, we reconciliate two formulations of gradient-based model fitting for the Fokker?Planck equation, arising from the PDE and particle formulation. Discretization yields gradient estimators that converge at the same rate in the number of particles. We conclude with work in progress on particle-based sampling methods and on uncertainty quantification for equations learned from data.
Weitere Informationen
Oberseminar “Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin
- 14. Dezember 2026 (WIAS-ESH)
- Workshop/Konferenz: Day on Optimal Transport
mehr ... Veranstaltungsort
Weierstraß-Institut, Anton-Wilhelm-Amo-Str. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Veranstalter
Technische Universität Berlin
WIAS Berlin
- 18. Februar 2027 (WIAS-ESH)
- Workshop/Konferenz: From Variational Journeys to Julian Flux Approximations
mehr ... Veranstaltungsort
Weierstraß-Institut, Anton-Wilhelm-Amo-Str. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal
Abstrakt
The WIAS Research Group "Scientific Computing and Numerical Analysis" has two reasons to celebrate: Volker John, head of the group, is turning 60, and Jürgen Fuhrmann, deputy head, has already turned 65. To mark the occasion, we are planning a small informal workshop.
Veranstalter
WIAS Berlin