Veranstaltungskalender
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Veranstaltungskalender April 2012

Mai 2012 >>
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11 Einträge gefunden

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  • 02. April
    14:00 - 16:00
    Ort: 46-110
    Graduate School

    Christoph Heinrich: A Finite Volume Method on NURBS Geometries and its Application in Fluid Flow and Isogeometric Fluid-Structure Interaction

  • 03. April
    11:00 - 11:30
    Ort: 48-582
    AG Differential-Algebraische Systeme

    Prof. Dr. Gerhard Starke (Leibniz Universität Hannover): Gemischte Finite-Element-Approximation für Spannungs-Verschiebungs-Formulierungen bei hyperelastischen Materialien

    Ein gemischter Finite-Element-Ansatz für nichtlineare Elastizitätsberechnungen auf der Basis hyperelastischer Materialgesetze wird vorgestellt. Dabei werden sowohl die Verschiebungskomponenten als auch der Piola-Kirchhoffsche Spannungstensor mit geeigneten finiten Elementen approximiert. Ein wesentlicher Bestandteil der zugrundeliegenden Formulierung als System erster Ordnung ist die Invertierung der nichtlinearen Beziehung zwischen dem Spannungstensor und dem Cauchy-Greenschen Verzerrungstensor. Die Approximationseigenschaften dieses Ansatzes werden an einschlägigen Testproblemen für nichtlineare Elastizitätsberechnungen illustriert.

  • 13. April
    12:00 - 14:00
    Ort: 48-208
    Graduate School

    Christian Eder: Signature-based algorithms to compute standard bases

  • 13. April
    15:00 - 17:00
    Ort: 48-208
    Graduate School

    Uditha Prabhath Liyanage: Parameter Identification Based on Occupation Times with Application to Fleece Production

  • 17. April
    15:30 - 17:00
    Ort: 46-260
    Graduate School

    Elisa Röhrig: Quantum Energy-Transport Models for Semiconductors

  • 20. April
    14:15 - 15:45
    Ort: 48-208
    Graduate School

    Evgeniy Zharovsky: Fast Numerical Algorithms for Advection-Diffusion Equations and Applications in Particle Dynamics

  • 23. April
    13:45 - 15:15
    Ort: 36-265
    Center for Mathematical and Computational Modelling (CM)^2, AG Optimierung

    Prof. Dr. David M. Ryan (University of Auckland): The Train Driver Disruption Recovery Problem - A Decision Support Framework and Solution Method

    Kategorie: AG Optimierung

    When unforeseen disruption occurs in daily railway operations, some of the original driver duties become infeasible and this requires real-time scheduling to generate new feasible driver recovery duties. In this talk Prof. Ryan will describe his joint work with Natalia Rezanova in which they develop an optimization-based solution method for solving the Train Driver Recovery Problem (TDRP). The solution framework attempts to minimize the amount of disruption to the original duties. This is achieved by solving restricted TDRP instances in a “disruption neighbourhood” with a rolling time horizon. We formulate the TDRP as a set partitioning model where variables represent train driver recovery duties and show why the proposed model and solution method is particularly suitable for solving in real-time. Recovery duties are generated as resource constrained shortest paths in duty networks, and the set partitioning problem is solved with a linear programming based branch-and-price algorithm. Dynamic column generation and recovery neighbourhood expansion at each node of the branch-and-price tree together with a constraint branching strategy contribute to the solution method. Real-life operational data was provided by DSB S-tog A/S (the suburban rail operator in Copenhagen) in order to test the implemented solution method. Based on the computational experiments, we conclude that the proposed approach can provide a practical decision support system for train driver dispatchers.

  • 24. April
    17:15 - 18:45
    Ort: 48-210
    Felix-Klein-Zentrum

    Felix-Klein-Kolloquium: Prof. Dr. Michael Röckner, Universität Bielefeld - Regularization of Ordinary and Partial Differential Equations by Noise

    It is a well-known phenomenon that an ordinary differential equation becomes "more regular", if one adds a noise term, as e.g. a stochastic differential given by a Brownian motion. On the level of the associated Fokker-Planck-Kolmogorov equations (FPKE), whose solutions are just the transition probabilities of the resulting solution process, this becomes more or less obvious, since the FPKE becomes elliptic, if the noise is not degenerate. From a purely analytic point of view, this regularizing property of the noise is most impressively manifested by the fact that noise can "produce" (existence and, in particular) uniqueness of solutions . Indeed, e.g. a classical result of A. Yu. Veretennikov, tells us that, given an initial condition, any two corresponding solutions of an ordinary differential equation in d- dimensional Euclidean space given by a just measurable bounded vector field and perturbed by the differential of a d-dimensional Brownian path, coincide for almost every such path. In contrast to this, in the deterministic case, neither existence nor uniqueness of solutions hold in such a case.

    The purpose of this talk is to present recent results of the same type, but for partial differential equations perturbed by noise, i.e. for the infinite dimensional analogue of the situation described above.

  • 25. April
    09:30 - 11:00
    Ort: Fraunhofer ITWM, Z14.04
    Graduate School

    Galina Printsypar: Mathematical Modeling and Simulation of two-phase flow in porous media with application to the pressing section of a paper machine

  • 26. April
    16:00 - 17:00
    Ort: Felix-Klein-Zentrum
    AG Computational Stochastics

    Daniel Henkel: Pointwise Approximation of Coupled Ornstein-Uhlenbeck Processes

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