Upcoming Events

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Thursday, 25.07.2019, 10:00 (WIAS-406)
Seminar Materialmodellierung
Dr. Robert Style, ETH Zürich, Schweiz:
Arresting phase separation with polymer networks
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Abstract
Some of the most beautiful colours in nature are seen in birds that have developed materials with extremely monodisperse, colloidal microstructures (these yield vivid structural colours). Previously it has been suggested that these can be grown by a process of arrested phase separation. Here, we take inspiration from such natural materials to grow composites with a uniform microstructure via a process of phase separation in an elastic gel network. These composites consist of uniform liquid droplets embedded in an elastic gel. The size of the droplets can be easily tuned with a number of different parameters, and presents an interesting challenge for modelling. I will also discuss how this process has applications in colloidal synthesis and phase-separation processes in living cells.

Host
WIAS Berlin
Friday, 02.08.2019, 15:15 (WIAS-ESH)
MATHEON Special Guest Lecture
Prof. Ya-Xiang Yuan, Chinese Academy of Sciences, China:
Efficient optimization algorithms for large scale data analysis
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
In this talk, two classes of problems in large scale data analysis and their optimization algorithms will be discussed. The first class focuses on composite convex program problems, where I introduce algorithms including a regularized semi-smooth Newton method, a stochastic semi-smooth Newton method and a parallel subspace correction method. The second class is on optimization with orthogonality constraints, particularly on parallelizable approaches for linear eigenvalue problems and nonlinear eigenvalue problems, and quasi-Newton type methods. Numerical results of applications, e.g., electronic structure calculations, $l_1$-regularized logistic regression problems, Lasso problems and Hartree-Fock total energy minimization problems, will be highlighted.

Further Informations
Special Guest Lecture

Host
WIAS Berlin
August 3 – 8, 2019 (TU-Berlin)
Workshop/Konferenz: 6th International Conference on Continuous Optimization
more ... Location
Technische Universität, Straße des 17. Juni 135, 10623 Berlin, Main building (H)

Further Informations
https://iccopt2019.berlin/

Host
WIAS Berlin
Technische Universität Berlin
Freie Universität Berlin
Humboldt-Universität zu Berlin
Mathematical Optimization Society
Monday, 19.08.2019, 15:00 (WIAS-ESH)
Forschungsseminar Mathematische Modelle der Photonik
Emil Vosmar Denning, Technical University of Denmark:
Accurate few-mode models of highly structured photonic reservoirs
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
WIAS Berlin
Tuesday, 03.09.2019, 13:30 (WIAS-ESH)
Seminar Numerische Mathematik
Dr. Yori Fournier, Leibniz-Institut für Astrophysik Potsdam (AIP):
Non-local effects in the solar dynamo
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
Model of the solar dynamo hardly reproduce the observations of the solar magnetic field. In the presence of strong magnetic field in a turbulent fully ionized medium, such as the solar interior, temporal and spacial re-correlations can occur. In the frame of mean-field MHD, these can be treated as spacial and temporal non-localities (memory effect). We found that the magnetic buoyancy occurring in the convective solar interior implies a non-linear temporal non-locality. This additional non-linearity leads to solutions that recover the morphological evolution of the solar magnetic field.

Host
WIAS Berlin
September 9 – 13, 2019 (WIAS-ESH)
Workshop/Konferenz: PDE 2019: Partial Differential Equations in Fluids and Solids
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
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.

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

Host
WIAS Berlin
Wednesday, 23.10.2019, 14:00 (WIAS-ESH)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
Prof. Dr. Ansgar Jüngel, Technische Universität Wien, Österreich:
Cross-diffusion systems: from spin semiconductors to biological populations with stochastic forcing
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
Many real-world applications consist of multiple components, leading on the macroscopic scale to cross-diffusion systems which consist of strongly coupled parabolic equations. The applications may be very diverse and range from spin-polarized transport in semiconductors and ion transport in cell membranes to population dynamics. In this talk, some existence results for global-in-time weak solutions is proved, based on entropy methods. This technique was already used by Herbert Gajewski, and we detail some of his ideas to prove the large-time behavior and uniqueness of weak solutions, followed by some extensions like boundedness-by-entropy and martingale solutions to stochastic cross-diffusion systems.

Host
Humboldt-Universität zu Berlin
WIAS Berlin