Browsing Preprints aus dem Institut für Mathematik by Title
Now showing items 322 of 327

20110920BuchA combined BDFsemismooth Newton approach for timedependent Bingham flow This paper is devoted to the numerical simulation of timedependent convective Bingham flow in cavities. Motivated by a primaldual regularization of the stationary model, a family of regularized timedependent problems ...

20060101BuchA convergent adaptive finite element method for an optimal design problem Abstract. The optimal design problem for maximal torsion stiffness of an infinite bar of given geometry and unknown distribution of two materials of prescribed amounts is one model example in topology optimisation. It ...

20050805BuchA Convergent Adaptive Finite Element Method For The Primal Problem Of Elastoplasticity The boundary value problem representing one time step of the primal formulation of elastoplasticity with positive hardening leads to a variational inequality of the second kind with some nondifferentiable functional. This ...

20060101BuchA Domain Decomposition method based on iterative Operator Splitting method. In this article a new approach is proposed for constructing domain decomposition methods based on iterative operator splitting methods. We study the convergence properties of such a method. The main feature of the method ...

19950426BuchA Dual Method for the Unit Commitment Problem In this paper a method for solving a midterm unit commitment problem in a large scale thermal power system is presented. This method is based on Lagrangian relaxation and uses a bundle method for solving the nonsmooth ...

20030624BuchA first approach to generalized polar varieties Let W be a closed algebraic subvariety of the ndimensional projective space over the complex or real numbers and suppose that W is nonempty and equidimensional. In this paper we generalize the classic notion of polar ...

20070417BuchA fourth order split scheme for elastic wavepropagation Motivated by seismological problems we have studied a 4th order split scheme for the elastic wave equation. We split in the spatial directions and obtain locally onedimensional systems to be solved. We have analyzed the ...

20051117BuchA Generalization of the Fundamental Estimates for Wm,p Solutions of Linear Systems with Constant Coefficients (the case 1 < p < 2) The aim of the present paper is to extent the well known fundamental estimates (w.r.t. the $L^2$norm) for weak solutions of a linear elliptic system with constant coefficients: \[ \sum_{ j= 1}^ N \sum_{\mid \alpha\mid,\mid ...

20060101BuchA Geometric Interpretation of Reduction in the Jacobians of C ab Curves In this paper, we show that the reduction of divisors in the Jacobian of a curve $C$ can be performed by considering the intersections of a suitable projective model of $C$ with quadrics in projective space. We apply this ...

20051021BuchA global L kgradient estimate on weak solutions to nonlinear stationary NavierStokes equations under mixed boundary conditions

20051020BuchA Global LpGradient Estimate on Weak Solutions of Nonlinear Parabolic Systems under Mixed Boundary Conditions In this paper, we prove the integrability of the spatial gradient Du to an exponent p>2 near the boundary, u being a weak solution of a nonlinear parabolic system under mixed boundary conditions. Our method of proof relies ...

20051115BuchA Global Optimality Criterion for Nonconvex Quadratic Programming over a Simplex In this paper we propose a global optimality criterion for globally minimizing a quadratic form over the standard simplex, which in addition provides a sharp lower bound for the optimal value. The approach is based on the ...

20110811BuchA Meyers' type estimate for weak solutions to a generalized stationary NavierStokes system In this paper, we prove a Meyers' type estimate for weak solutions to a Stokes system with bounded measurable coefficients in place of the usual constant viscosity. Besides the perturbation argument due to Meyers, we make ...

20051103BuchA modified standard embedding for linear complementarity problems We propose a modified standard embedding for solving the linear complementarity problem (LCP). This embedding is a special oneparametric optimization problem $P(t), t\in [0,1]$. Under the conditions (A3) (the Mangasaria ...

20051103BuchA modified standard embedding with jumps in nonlinear optimization The paper deals with a combination of pathfollowing methods (embedding approach) and feasible descent direction methods (socalled jumps) for solving a nonlinear optimization problem with equality and inequality constraints. ...

20051103BuchA necessary optimality condition for the linearquadratic DAE control problem We consider the linearquadratic optimal control problem for a controlled differential algebraic equation (DAE). Under minimal assumptions on the DAE concerning index and regularity it will be possible to prove that the ...

20110927BuchA new algorithm for the index determination in DAEs by Taylor series using Algorithmic Differentiation We present an approach for determining the tractability index using truncated polynomial arithmetic. In particular, computing the index this way generates a sequence of matrices that contains itself derivatives. We realize ...

20051115BuchA new approach to Lipschitz spaces of periodic integrable functions

19990802BuchA Nonlinear Parabolic System Modeling Chemotaxis with Sensitivity Functions We study a model for chemotaxis on a general Lipschitz domain where the chemotactic response is specified by sensitivity functions. After finding a Lyapunov function for the system, we demonstrate existence of global ...

19961001BuchA nonstandard finite difference method for the solution of linear second order boundary value problems with nonsmooth coefficients A new three point highly accurate finite difference method for solving linear second order differential equations is proposed. The coefficients of the scheme are constructed via differentiations of the differential equation. ...