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    Schlussbericht zum BMBF-Vorhaben: Compact optohybrids (CoOp), Teilvorhaben: Ionenätzverfahren für die Strukturierung
    (Hannover : Technische Informationsbibliothek (TIB), 2006) Schindler, Axel
    [no abstract available]
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    Forscherverbund: German Israeli cooperation in ultrafast laser technologies (GILCULT) : Projekt: Femtosecond coherent control for nonlinear spectroscopy ; Abschlußbericht
    (Hannover : Technische Informationsbibliothek (TIB), 2004) Korn, G.; Silberberg, Yaron; Zhavoronkov, Nikolay; Laarmann, Tim
    [no abstract available]
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    Resolution of symplectic cyclic orbifold singularities
    (Oberwolfach : Mathematisches Forschungsinstitut Oberwolfach, 2007) Niederkrüger, Klaus; Pasquotto, Federica
    In this paper we present a method to obtain resolutions of symplectic orbifolds arising as quotients of pre-symplectic semi-free S1–actions. This includes, in particular, all orbifolds arising from symplectic reduction of Hamiltonian S1–manifolds at regular values, as well as all isolated cyclic orbifold singularities. As an application, we show that pre-quantisations of symplectic orbifolds are symplectically fillable by a smooth manifold.
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    The McKay conjecture for exceptional groups and odd primes
    (Oberwolfach : Mathematisches Forschungsinstitut Oberwolfach, 2007) Späth, Britta
    Let G be a simply-connected simple algebraic group over an algebraically closed field of characteristic p with a Frobenius map F : G ! G and G := GF , such that the root system is of exceptional type or G is a Suzuki-group or Steinberg’s triality group. We show that all irreducible characters of CG(S), the centraliser of S in G, extend to their inertia group in NG(S), where S is any F-stable Sylow torus of (G, F). Together with the work in [17] this implies that the McKay-conjecture is true for G and odd primes ` different from the defining characteristic. Moreover it shows important properties of the associated simple groups, which are relevant for the proof that the associated simple groups are good in the sense of Isaacs, Malle and Navarro, as defined in [15].
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    New results on the stability of quasi-static paths of a single particle system with Coulomb friction and persistent contact
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2006) Schmid, Florian; Martins, J.A.C.; Rebrova, Natalia
    In this paper we announce some new mathematical results on the stability of quasi-static paths of a single particle linearly elastic system with Coulomb friction and persistent normal contact with a flat obstacle.A quasi-static path is said to be stable at some value of the load parameter if, for some finite interval of the load parameter thereafter, the dynamic solutions behave continuously with respect to the size of the initial perturbations (as in Lyapunov stability) and to the smallness of the rate of application of the external forces, $varepsilon$ (as in singular perturbation problems). In this paper we prove sufficient conditions for stability of quasi-static paths of a single particle linearly elastic system with Coulomb friction and persistent normal contact with a flat obstacle. The present system has the additional difficulty of its non-smoothness: the friction law is a multivalued operator and the dynamic evolutions of this system may have discontinuous accelerations.
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    A jump-diffusion Libor model and tits robust calibration
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2006) Belomestrny, Denis; Schoenmakers, John G.M.
    In this paper we propose a jump-diffusion Libor model with jumps in a high-dimensional space and test a stable non-parametric calibration algorithm which takes into account a given local covariance structure. The algorithm returns smooth and simply structured Lévy densities, and penalizes the deviation from the Libor market model. In practice, the procedure is FFT based, thus fast, easy to implement, and yields good results, particularly in view of the ill-posedness of the underlying inverse problem.
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    Simulationsbasierte Regelung der Laserhärtung von Stahl
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2006) Alder, Holger; Hömberg, Dietmar; Weiss, Wolf
    Bei der Oberflaechenhärtung mit Hilfe von Laserstrahlen ist eine konstante Einhärtetiefe erwünscht, wobei gleichzeitig Anschmelzungen vermieden werden sollen. Um Anschmelzungen zu verhindern, kann die Temperatur im Auftreffpunkt des Lasers gemessen werden und die Laserleistung entsprechend geregelt werden. Eine konstante Temperatur fährt bei geometrisch komplizierten Bauteilen jedoch nicht zu einer konstanten Einhärtetiefe. In dieser Arbeit wird ein Verfahren aufgezeigt, wobei durch numerische Simulationen eine nichtkonstante Oberflächentemperatur berechnet wird, die eine konstante Einhärtetiefe liefert. Die berechnete Oberflächentemperatur kann als Solltemperatur im realen Prozess benutzt werden.
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    An optimisation method in inverse acoustic scattering by an elastic obstacle
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2008) Elschner, Johannes; Hsiao, George C.; Rathsfeld, Andreas
    We consider the interaction between an elastic body and a compressible inviscid fluid, which occupies the unbounded exterior domain. The inverse problem of determining the shape of such an elastic scatterer from the measured far field pattern of the scattered fluid pressure field is of central importance in detecting and identifying submerged objects. Following a method proposed by Kirsch and Kress, we approximate the acoustic and elastodynamic wave by potentials over auxiliary surfaces, and we reformulate the inverse problem as an optimisation problem. The objective function to be minimised is the sum of three terms. The first is the deviation of the approximate far field pattern from the measured one, the second is a regularisation term, and the last a control term for the transmission condition. We prove that the optimisation problem has a solution and that, for the regularisation parameter tending to zero, the minimisers tend to a solution of the inverse problem. In contrast to a numerical method from a previous paper, the presented method does require neither a direct solution method nor an additional treatment of possible Jones modes.
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    Geometric quantization of integrable systems with hyperbolic singularities
    (Oberwolfach : Mathematisches Forschungsinstitut Oberwolfach, 2009) Hamilton, Mark D.; Miranda, Eva
    We construct the geometric quantization of a compact surface using a singular real polarization coming from an integrable system. Such a polarization always has singularities, which we assume to be of nondegenerate type. In particular, we compute the effect of hyperbolic singularities, which make an infinite-dimensional contribution to the quantization, thus showing that this quantization depends strongly on polarization.