Preprint Sfb

Technische Universitat Chemnitz (2003)

In this paper, a uniformly elliptic second order boundary value problem in 2D is discretized by the p-version of the finite element method. An inexact Dirichlet-Dirichlet domain decomposition...

Fast Solvers for Degenerated Problems (2003)

Contents 1 Introduction 1 2.1.1 Invoking Graphics Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.1.2 Specify Menu Names for the Degrees of Freedom . . . . . . . . . . . . . . . 2...

Fast Solvers for Degenerated Problems (2003)

In this paper, finite element discretizations of the degenerated operator -# (y)u xx (x)u yy = g in the unit square are investigated, where the weight function satisfies #(#) = 0. We propose two...

A posteriori error estimation for the Stokes problem: Anisotropic . . . (2003)

In this paper, nite element discretizations of the degenerated operator -# (y)u xx (x)u yy = g in the unit square are investigated, where the weight function satises #(#) = 0. We propose two...

Emmanuel Creuse, Gerd Kunert, Serge Nicaise, Preprint Sfb

The paper presents a posteriori error estimators for the stationary Stokes problem. We consider anisotropic finite element discretizations (i.e. elements with very large aspect ratio) where...

A posteriori error estimation for the Stokes (2003)

Gerd Kunert, Serge Nicaise, Preprint Sfb

The paper presents a posteriori error estimators for the stationary Stokes problem.

Numerische Simulation auf massiv parallelen Rechnern (2003)

Preprint Sfb, Gudula R Unger, Tu Chemnitz

The characteristics of irregular algorithms make a parallel implementation difficult, especially for PC clusters or clusters of SMPs. These characteristics may include an unpredictable access...

Technische Universitat Chemnitz (2002)

Technische Universitat Chemnitz (2002)

In this paper we consider the fully discrete wavelet Galerkin scheme for the fast solution of boundary integral equations in three dimensions. It produces approximate solutions within discretization...

Adaptive Wavelet Galerkin BEM (2002)

In this paper we consider the fully discrete wavelet Galerkin scheme for the fast solution of boundary integral equations in three dimensions. It produces approximate solutions within discretization...

Adaptive Wavelet Galerkin BEM (2002)

The wavelet Galerkin scheme for the fast solution of boundary integral equations produces approximate solutions within discretization error accuracy offered by the underlying Galerkin method at a...

Visualization Tools for 2D and 3D Finite Element Programs - User's Manual (2002)

The wavelet Galerkin scheme for the fast solution of boundary integral equations produces approximate solutions within discretization error accuracy o#ered by the underlying Galerkin method at a...

Compression Techniques for Boundary Integral Equations - Optimal . . . (2002)

Contents 1 Introduction 1 2.1.1 Invoking Graphics Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.1.2 Specify Menu Names for the Degrees of Freedom . . . . . . . . . . . . . . . 2...

Preprint Sfb, W. Dahmen, H. Harbrecht, R. Schneider, Tu Chemnitz

In this paper matrix compression techniques in the context of wavelet Galerkin schemes for boundary integral equations are developed and analyzed that exhibit optimal complexity in the following...

Wavelet Galerkin Schemes for 3D-BEM (2002)

H. Harbrecht, R. Schneider, Preprint Sfb

This paper is intended to present wavelet Galerkin schemes for the boundary element method. Wavelet Galerkin schemes employ appropriate wavelet bases for the discretization of boundary integral...

Fully Discrete Wavelet Galerkin Schemes (2002)

H. Harbrecht, M. Konik, R. Schneider, Preprint Sfb

The present paper is intended to give a survey of the developments of the wavelet Galerkin boundary element method. Using appropriate wavelet bases for the discretization of boundary integral...

Computation of 3D vertex singularities for linear elasticity: Error . . . (2001)

Ig S. I. Solov'ev, Th. Apel A. -m. S, Preprint Sfb

This paper is concerned with the computation of 3D vertex singularities of anisotropic elastic fields with Dirichlet boundary conditions, focusing on the derivation of error estimates for a finite...

Computation of 3D vertex singularities for linear elasticity: Error estimates for (2001)

Technische Universitat Chemnitz, Preprint Sfb

This paper is concerned with the computation of 3D vertex singularities of anisotropic elastic elds with Dirichlet boundary conditions, focusing on the derivation of error estimates for a nite...

The Adaptive Finite Element Method - Can We Solve Arbitrarily Accurate? (2001)

Programmer's Manual for Adaptive Finite Element Code SPC - PM 2Ad (2001)

In the adaptive finite element method, the solution of a p.d.e. is approximated by finer and finer meshes, which are controlled from error estimators. So, starting from a given coarse mesh, some...

Technische Universitat Chemnitz (2001)

Contents 1 Overview 1 1.1 The Partial Differential Equations to be Approximated . . . . . . . . . . . . . . 1 1.2 Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3...

Technische Universit at Chemnitz (2001)

In the adaptive finite element method, the solution of a p.d.e. is approximated by finer and finer meshes, which are controlled from error estimators. So, starting from a given coarse mesh, some...

Least squares methods for the coupling of FEM and BEM (2001)

Contents 1 Overview 1 1.1 The Partial Differential Equations to be Approximated . . . . . . . . . . . . . . 1 1.2 Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3...

G. Gattica, H. Harbrecht, R. Schneider, Preprint Sfb

In the present paper we propose least squares formulations for the numerical solution of exterior boundary value problems. The partial differential equation is a first order system in a bounded...

An Adaptive Regularization By Projection for Noisy . . . (2001)

H. Harbrecht, S. Pereverzev, R. Schneider, Preprint Sfb

It is well known, that pseudodifferential equations of negative order considered in the Sobolev space with a small smoothness index are ill--posed. On the other hand, it is known that efficient...

Numerical Studies of Shape Optimization Problems in Elasticity using . . . (2001)

Helmut Harbrecht, Preprint Sfb

this paper, the knowledge of its normal derivative suffices to evaluate the data appearing from the torsional rigidity. Invoking a Newton potential, the normal derivative can be represented by a...

Structured Eigenvalue Methods for the Computation of Corner Singularities in . . . (2001)

Th. Apel, V. Mehrmann, D. Watkins, Preprint Sfb

This paper is concerned with the computation of 3D vertex singularities of anisotropic elastic fields. The singularities are described by eigenpairs of a corresponding operator pencil on a subdomain...

Structured Eigenvalue Methods for the Computation of Corner Singularities in . . . (2001)

Technische Universitat Chemnitz, Th. Apel, V. Mehrmann, D. Watkins, Preprint Sfb

This paper is concerned with the computation of 3D vertex singularities of anisotropic elastic elds. The singularities are described by eigenpairs of a corresponding operator pencil on a subdomain of...

Stability of discretizations of the Stokes problem on anisotropic . . . (2001)

Thomas Apel, H. Maharavo Randrianarivony, Preprint Sfb

Anisotropic features of the solution of flow problems are usually approximated on anisotropic (large aspect ratio) meshes. This paper reviews stability results of several velocity-pressure pairs with...

Stability of discretizations of the Stokes problem on anisotropic . . . (2001)

Thomas Apel, H. Maharavo Randrianarivony, Preprint Sfb

Anisotropic features of the solution of flow problems are usually approximated on anisotropic (large aspect ratio) meshes. This paper reviews stability results of several velocity-pressure pairs with...

Strengthened Cauchy inequality in anisotropic meshes and application to an . . . (2001)

Maharavo Randrianarivony, Stokes Problem, Preprint Sfb

In this document, we show an a-posteriori error estimator which is efficient and reliable even on highly stretched meshes for the Crouzeix-Raviart/P 0 pair. It relies on hierarchical space splitting...

Improvements and Experiments on the Bramble-Pasciak Type CG for Mixed Problems (2001)

Arnd Meyer, Torsten Steidten, Preprint Sfb

The authors present a generalization of the preconditioning technique introduced by Bramble and Pasciak. It is shown that this generalized variant in connection with the conjugate gradient method...

Improvements and Experiments on the Bramble-Pasciak Type CG for Mixed Problems in . . . (2001)

Technische Universitat Chemnitz, Arnd Meyer, Torsten Steidten, Preprint Sfb

The authors present a generalization of the preconditioning technique introduced by Bramble and Pasciak. It is shown that this generalized variant in connection with the conjugate gradient method...

Preconditioning for the p-version of the FEM by bilinear elements (2001)

SPC-PM3AdH v1.0 - Programmer's Manual (2001)

Finding a fast solver for the inner problem in a DD preconditioner for the p-version of the FEM is a di#cult question. We discovered, that the system matrix for the inner problem in any dimension has...

Preprint Sfb, G. Kunert, D. Lohse, F. Milde, M. Pester, U. Reichel, ...

this documentation we use slanted style for real existing paths and filenames, emphasis style for program parameters, sans serif style to characterize buttons and menu items of programs with a...

SPC-PM3AdH v1.0 - Programmer's Manual (2001)

Technische Universitat Chemnitz, Preprint Sfb, G. Kunert, D. Lohse, F. Milde, M. Pester, ...

this documentation we use slanted style for real existing paths and lenames, emphasis style for program parameters, sans serif style to characterize buttons and menu items of programs with a...

The MTS-BPX-preconditioner for the p-Version of the fem (2001)

Nitsche Mortar Finite Element Method for Transmission Problems With Singularities (2001)

Finding a fast solver for the inner problem in a DD preconditioner for the p-version of the FEM is a difficult question. We discovered, that the system matrix for the inner problem in any dimension...

Bernd Heinrich, Preprint Sfb

The paper deals with Nitsche type finite element method (FEM) for treating nonmatching meshes at the interface of some domain decomposition. This method is applied to some transmission (or interface)...

Nitsche Mortar Finite Element Method for Transmission Problems With . . . (2001)

Bernd Heinrich, Serge Nicaise, Preprint Sfb

The paper deals with Nitsche type finite element method (FEM) for treating nonmatching meshes at the interface of some domain decomposition. This method is applied to some transmission (or interface)...

CHEMPI: Efficient MPI for VIA/SCI (2001)

Khaled Ragab, Wolfgang Rehm, Preprint Sfb

Although many ideas about protected user-level network access have been around for a while there still hasn't been a satisfying solution to combine extreme low-latency and highbandwidth over a wide...

Technische Universit at Chemnitz (2001)

Daniel Balkanski, Friedrich Seifert, Wolfgang Rehm, Preprint Sfb

In this document we present the architectural design we develop for the system software, which integrates our new architecture PCI--SCI Bridge with VIA support into the LINUX operating system. The...

Technische Universitat Chemnitz (2001)

Technische Universitat Chemnitz, Thomas Apel, Sergei Grosman, Peter K. Jimack, Arnd Meyer, Preprint Sfb

We introduce a new strategy for controlling the use of anisotropic mesh renement based upon the gradients of an a posteriori approximation of the error in a computed nite element solution. The...

A preconditioner for solving the inner problem of the p-version of the FEM, Part II- algebraic . . . (2001)

Technische Universitat Chemnitz, Sven Beuchler, Preprint Sfb

Finding a fast solver for the inner problem in a DD preconditioner for the p-version of the FEM is a dicult question. We discovered, that the system matrix for the inner problem in 2D has a similar...

A Note on the Energy Norm for a Singularly Perturbed Model Problem (2001)

Technische Universitat Chemnitz, Gerd Kunert, Preprint Sfb

A singularly perturbed reaction{diusion model problem is considered, and the choice of an appropriate norm is discussed. Particular emphasis is given to the energy norm. Certain prejudices against...

Generalized Lyapunov Equations for Descriptor Systems: Stability and Inertia Theorems (2000)

Tatjana Stykel, Preprint Sfb

We study generalized Lyapunov equations and present generalizations of Lyapunov stability theorems and some matrix inertia theorems for matrix pencils. We discuss applications of generalized Lyapunov...

Cholesky-like Factorizations of Skew-Symmetric Matrices (2000)

Peter Benner, Ralph Byers, Volker Mehrmann, David Watkins, Preprint Sfb

Every real skew-symmetric matrix B admits Cholesky-like factorizations B = R T JR where J = h 0 I I 0 i . This paper presents a backward-stable O(n 3 ) process for computing such a decomposition, in...

Algorithms for Model Reduction of Large Dynamical Systems (2000)

Technische Universitat Chemnitz, Thilo Penzl, Preprint Sfb

Three algorithms for the model reduction of large-scale, continuous-time, timeinvariant, linear, dynamical systems with a sparse or structured transition matrix and a small number of inputs and...

A Robust ILU Based on Monitoring the Growth of the Inverse Factors (2000)

On an Augmented Lagrangian SQP Method for a Class of Optimal Control Problems in Banach Spaces (2000)

An incomplete LU decomposition with pivoting is presented that progressively monitors the growth of the inverse factors of L; U . The information on the growth of the inverse factors is used as...

N. Arada, J. -p. Raymond, Preprint Sfb

An augmented Lagrangian SQP method is discussed for a class of nonlinear optimal control problems in Banach spaces with constraints on the control. The convergence of the method is investigated by...

Two Boundary Element Methods for the clamped plate (2000)

Christian Bourgeois, Preprint Sfb

In this paper we retail the approximation of the clamped plate problem by means of two boundary element methods. In both cases, the variational formulation is given on product of Sobolev spaces and...

On a Quadrature Algorithm for the Piecewise Linear Wavelet Collocation Applied to Boundary Integral Equations (2000)

Preprint Sfb, Andreas Rathsfeld, Reinhold Schneider, Tu Chemnitz

In this paper we consider a piecewise linear collocation method for the solution of a pseudo-differential equation of order r = 0, -1 over a closed and smooth boundary manifold. The trial space is...

On Fractional Exponents in Perturbed Matrix Spectra of . . . (2000)

Mihail Konstantinov, Volker Mehrmann, Petko Petkov, Preprint Sfb

In this paper we discuss the perturbation theory for defective matrices. We consider the asymptotic expansions of the perturbed spectrum, when the matrix A is perturbed to A + tE and in particular we...

SPC-PM Po 3D v4.0 - Programmer's Manual (Part II) (2000)

Preprint Sfb, Thomas Apel, Technische Universitat Chemnitz, Frank Milde, Uwe Reichel

this documentation we use slanted style for real existing paths and lenames, italic style for program parameters, sans serif style to characterize buttons and menu items of programs with a graphical...

Multiscale Preconditioning for the Coupling of FEM-BEM (2000)

Helmut Harbrecht, Freddy Paiva, Reinhold Schneider, Multiscale Preconditioning For The, Preprint Sfb

. We apply multiscale methods to the coupling of nite and boundary element methods to solve an exterior two dimensional Laplacian. The matrices belonging to the boundary terms of the coupled FEM-BEM...

Some Multilevel Methods on Graded Meshes (2000)

M. Jung, S. Nicaise, J. Tabka, Preprint Sfb

We consider Yserentant's hierarchical basis method and multilevel diagonal scaling method on a class of refined meshes used in the numerical approximation of boundary value problems on polygonal...

A Unified Deflating Subspace Approach for Classes of Polynomial and Rational Matrix Equations (2000)

Peter Benner, Ralph Byers, Volker Mehrmann, Hongguo Xu, Preprint Sfb

A unified deflating subspace approach is presented for the solution of a large class of matrix equations, including Lyapunov, Sylvester, Riccati and also some higher order polynomial matrix equations...

Some Remarks on the Constant in the Strengthened C.B.S. Inequality: Application to h- and p-Hierarchical Finite Element Discretizations of Elasticity Problems (2000)

M. Jung, J. F. Maitre, Preprint Sfb

For a class of two-dimensional boundary value problems including diffusion and elasticity problems it is proved that the constants in the corresponding strengthened Cauchy-Buniakowski-Schwarz...

Decay Bounds for Solutions of Lyapunov Equations: The Symmetric Case (2000)

Technische Universitat Chemnitz, Thilo Penzl, Preprint Sfb

We present two new bounds for the eigenvalues of the solutions to a class of continuous-time and discrete-time Lyapunov equations. These bounds hold for Lyapunov equations with symmetric coecient...

Numerical Computation of Deflating Subspaces of Embedded Hamiltonian Pencils (2000)

Peter Benner, Ralph Byers, Volker Mehrmann, Hongguo Xu, Preprint Sfb

We discuss the numerical solution of structured generalized eigenvalue problems that arise from linear-quadratic optimal control problems, H1 optimization, multibody systems and many other areas of...

Convergence of the Modified Subspace Iteration Method for Nonlinear Eigenvalue Problems (1999)

Sergey I. Solov'ev, Technische Universitat Chemnitz, Preprint Sfb

The existence of eigenvalues of a finite-dimensional eigenvalue problem with nonlinear entrance of a spectral parameter is studied. The modified subspace iteration method is suggested for solving the...

On a Criterion for Asymptotic Stability of Differential-Algebraic Equations (1999)

Tatjana Stykel, Preprint Sfb

This paper discusses Lyapunov stability of the trivial solution of linear differentialalgebraic equations. As a criterion for the asymptotic stability we propose a numerical parameter ae(A; B)...

Domain Decomposition for Isotropic and Anisotropic Elliptic Problems (1999)

Preprint Sfb, Sergei V. Nepomnyaschikh

this paper we design preconditioning operators for the system of grid equations approximating the following boundary value problem. 8 ? ? ? ! ? ? ? : Gamma 2 X i;j=1 @ @x i ` a ij (x) @u @x j ' + a 0...

Projected PCGM for Handling Hanging Nodes in Adaptive Finite Element Procedures (1999)

Infinite Eigenvalues and the QZ Algorithm (1999)

We consider an adaptive finite element method using so called 'hanging nodes' from subdividing an edge of the actual f.e. mesh and subdividing only one of the adjacent triangles (or quadrilaterals)...

David S. Watkins, Preprint Sfb

The implicitly shifted (bulge chasing ) QZ algorithm is the most popular method for solving the generalized eigenvalue problem Av = Bv. This paper explains why the QZ algorithm functions well even in...

Two-Stage Testing of Advanced Dynamic Subgrid-Scale Models for Large-Eddy. . . (1999)

Klaus Bernert, Preprint Sfb

The investigations of the present work are intended to contribute to improvements in dynamic subgrid-scale (SGS) modelling for large-eddy simulation (LES) on high-performance parallel computers....

Technische Universitat Chemnitz (1999)

Klaus Bernert, Preprint Sfb

The investigations of the present work are intended to contribute to improvements in dynamic subgrid-scale (SGS) modelling for large-eddy simulation (LES) on high-performance parallel computers....

Treating Curved Surfaces in a 3D Finite Element Program for Parallel Computers (1999)

Technische Universitat Chemnitz (1999)

This paper provides both a simple and for many purposes sufficient method of defining and dealing with curved surfaces in a 3D Finite Element program ([1], [10], [12], [13]). Automatic mesh...

Thomas Apel, Uwe Reichel, Preprint Sfb

this documentation were written together with F. Milde and G. Globisch, respectively, Section 3.6 was written by D. Lohse. The tests in Section 4 were partially carried out by A. Meyer and U....

Technische Universitt Chemnitz (1999)

Technische Universitt Chemnitz, Preprint Sfb, Thomas Apel, Tu Chemnitz

the mesh size or some (small perturbation) parameter tends to zero. Contrary, elements are called isotropic if the aspect ratio is bounded by a moderate constant. Triangular elements are isotropic if...

SPC-PM Po 3D V3.3 - User's Manual (1999)

Thomas Apel, Uwe Reichel, Preprint Sfb

this documentation were written together with F. Milde and G. Globisch, respectively, Section 3.6 was written by D. Lohse. The tests in Section 4 were partially carried out by A. Meyer and U....

Anisotropic Finite Elements: Local Estimates and Applications (1999)

Technische Universitt Chemnitz, Preprint Sfb, Thomas Apel, Tu Chemnitz

The solution of elliptic boundary value problems my have...

Anisotropic Finite Elements: Local Estimates and Applications (1999)

Technische Universitt Chemnitz, Preprint Sfb, Thomas Apel, Tu Chemnitz

this report. To develop the main ideas we introduce some basic notation. Assume that the boundary value problem is given in weak form: Find u 2 V 0 : a(u; v) = hf; vi 8v 2 V 0 : (1.1) Here we denote...

Hierarchical Preconditioners for Higher Order Elements and Applications in Computational Mechanics (1999)