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Event calendar

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<< May 2017

Event Calendar June 2017

July 2017 >>

11 entries found

Page 1 of 2 12 >>

  • 02. June
    14:00 - 15:30
    Location: 32-349

    Dr. Özkaya, TU KL, Robust Aerodynamic Shape Optimization Using Adjoint Assisted Surrogate Modeling

    In the present work, we present an hybrid optimization framework for robust aerodynamic shape optimization. The suggested method combines a Kriging (also known as Gaussian process regression) based surrogate model with an adaptive sampling strategy assisted by the gradient information obtained from a discrete adjoint solver. In this way, it is possible to incorporate the uncertainties in design variables into the optimization algorithm. The feasibility of the suggested method is demonstrated by a comparative design optimization study using the benchmark test cases of the open source CFD software SU2.

  • 06. June
    13:45 - 16:00
    Location: 46-268

    Prof. Dr. Alfred Müller, Universität Siegen, Risikomaße

  • 08. June
    17:00 - 18:00
    Location: 48-436
    AG Algebra, Geometrie und Computer Algebra

    William Wong,TU Kaiserslautern: A phenomenon in the representation of SL(2,q) in defining

    I will talk about my PhD research, which uncovers some properties of modules of SL(2,q) in defining characteristics. It heavily depends on information from representations of its Borel subgroup, which is equivalent to the normaliser of the defect group in this case. In this talk I will present the results using combinatorial properties in the local representation.

  • 13. June
    11:30 - 13:15
    Location: 32-349

    Prof. Swanson, NASA; Transport Equations: Mathematical and Discrete Issues

    There is considerable effort to solve the problem of well-posedness, regularity, and global existence
    for the Navier-Stokes equations. While progress has been made for some particular cases, this
    Millennium problem remains unsolved in general. These issues also apply to the transport equation
    or equations for modeling the effects of turbulence. Without this mathematical foundation, one
    cannot know a priori if there exist a solution or possibly multiple solutions. Currently, scientists and
    engineers generally rely only upon numerical demonstrations to determine if there exist a realistic
    eddy viscosity from turbulence models, which primarily depends on solving transport equations.
    In this presentation, the mathematical and discrete issues concerning a representative two-equation
    turbulence model are examined. The challenges for convergence in steady state problems as well
    as unsteady problems, when considering a dual time-stepping algorithm, are discussed. Although
    the focus will be on a two-equation model, some representative convergence behaviors of a full
    Reynolds Stress Model (RSM) are also presented. Results are shown for three different airfoil cases
    at different flow conditions, which includes transonic flow conditions. Various issues in verification
    of turbulence models are also briefly considered. A perspective on requirements for an effective
    and efficient numerical algorithm to solve the transport equations is also examined. In particular,
    the following issues are considered: (1) stiffness of the governing transport equations, (2) boundary
    conditions, (3) positivity and realizability, (3) boundary conditions, (4) strong solution algorithms,
    (5) linear and nonlinear stability, (6) analysis concerning behavior of the transport equations.

  • 13. June
    17:00 - 18:00
    Location: 48-436
    AG Algebra, Geometrie und Computer Algebra

    Wolfgang Willems, Magdeburg: On quasi-projective Brauer characters

    We study p-Brauer characters of a finite group G which are restrictions of generalized characters vanishing on p-singular elements for a fixed prime p dividing the order of G. Such Brauer characters are called quasi-projective. We show that for each irreducible Brauer character there exists a minimal p-power, say pa(φ), such that pa(φ) φ is quasi-projective. The exponent a(φ) only depends on the Cartan matrix of the block to which  φ belongs. Moreover pa(φ)   is bounded by the vertex of the module afforded by φ, and equality holds in case that G is p-solvable. We give some evidence for the conjecture that  a(φ) occurs if and only if  φ belongs to a block of defect 0. Finally, we study indecomposable quasi-projective Brauer characters of a block B. This set is finite and corresponds to a minimal Hilbert basis of the rational cone defined by the Cartan matrix of B.

  • 18. June - 23. June


    Category: KOMMS

    Modellierungswoche für Schülerinnen und Schüler, Lehrkräfte und Referendarinnen und Referendare in der Pfalzakademie Lambrecht.

  • 22. June
    11:30 - 13:15
    Location: 32-349

    Prof. Pfetsch, TU Darmstadt, Compressed Sensing and Discrete Optimization

    The goal of this talk is to give an overview on compressed sensing from an discrete optimization/geometry point of view. The main problem in compressed sensing – the sparse representation problem – is to find the sparsest solutions of underdetermined linear equation systems. This problem is computationally hard, but can be efficiently solved by a linear program if certain conditions are satisfied. The talk will review some well known conditions and show that they are computationally hard to check. Moreover, the solution of this problem to global optimality will be discussed. The next step consists of presenting results on the unique recovery of integer solutions. Of course, even obtaining some feasible solution is hard in this case. Nevertheless, the potential of investing computational resources to obtain optimal solutions will be discussed.

  • 22. June
    17:00 - 18:00
    Location: 48-436
    AG Algebra, Geometrie und Computer Algebra

    Baptiste Rognerud, IRMA Strasbourg: A Morita theory for permutation modules

    It is known that the trivial source modules (or p-permutation modules) over a block of group algebra share a lot of similarities with the projective modules. For example, there are only finitely many of them, and working over a p-modular system, any trivial source module over the field of positive characteristic lifts uniquely to a trivial source module over the valuation ring. It has also been shown by Arnold that it is possible to do homological algebra with this family of modules.

    The aim of the talk is to explain what happens when you replace projective modules by trivial source modules in the classical Morita theory between blocks of group algebras. This is a joint work with Markus Linckelmann.

  • 27. June
    16:00 - 17:45
    Location: 32-349

    Prof.Ulbrich, Robust Nonconvex PDE-Constrained Optimization based on Second Order Approximation Techn. and Reduced Order Models

    We consider robust optimization techniques for nonconvex PDE-constrained problems involving uncertain parameters. The parameters are assumed to be contained in a given uncertainty set. This type of robust optimization problems are difficult to treat computationally and hence suitable approximations and solution methods are required. We propose and investigate an approximate robust formulation that employs a quadratic approximation (or only a linear approximation when appropriate) and can be solved efficiently by using a full-space formulation as mathematical program with equilibrium constraints (MPEC) or a reduced formulation. Moreover, we consider the application of reduced order models with a posteriori error estimation within the optimization method to reduce the number of required PDE-solves during the optimization.
    We show applications to the robust geometry optimization of a permanent magnet synchronous motor and to the robust geometry optimization of load-carrying structures governed by the elastodynamic equations.

    This is joint work with Oliver Lass and Philip Kolvenbach, TU Darmstadt.

  • 27. June
    17:15 - 18:15
    Location: Raum 48-210
    Fachbereich Mathematik

    Prof. Dr. Rüdiger Kiesel, Universität Duisburg-Essen, Empirics and Analytics for Intraday Power Markets

    We will give an introduction to short-term electricity markets. We will start with the relation of day-ahead and intraday prices on the EPEX for deliveries in Germany/Austria. In the sequel we will focus on analyzing the intraday market. We will discuss empirical properties of intraday power markets and point out development in recent years. Furthermore, we study the optimal liquidation and optimal market making problem for traders in intraday power markets.

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