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MPI-basierte Koppelrandkommunikation und Einfluß der Partitionierung im 3D-FallGrabowsky, L. 30 October 1998 (has links)
In der vorliegenden Arbeit wird die Anwendung eines bereits im 2D-Fall benutzten Mechanismus zur MPI-basierten Koppelrandkommunikation auf das 3D-FEM-System SPC PMPo-3D beschrieben. Insbesondere soll der Einfluss der Partitionierung auf die Laufzeit im Vergleich mit den Resultaten für das Originalsystem, fuer das entsprechende Untersuchungen bereits in durchgefuehrt wurden, betrachtet werden. Weiterhin wird ein Ausblick auf weitere Optimierungsmöglichkeiten des Verfahrens gegeben.
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Dynamic Analysis of a Window connected via the Click-In SystemBhatia, Abhikaran January 2022 (has links)
It is often needed to predict the behavior of structures. With the helpof an FE model, it is possible to see the motion of the structure. Inthis, Master thesis work time domain analyses were carried out on afinite element model representing a window attached by click-ins. Theaim was to establish an FE model which gives a good correlation withtest data. The finite element modelling was carried out in MSC Apex.MSC Nastran was utilised to analyze the FEA model and the resultwas post-processed in Simxpert. Different vibrational tests were made. A crane was used to exciteand support the wall together with the window and the responseswere recorded with tri-axial accelerometers. During the thesis, it wasfound that the FE model requires more work and accurate boundaryconditions to provide better resemblance with the test data.The results deviate from the measured. This opens future possibilities tocarry on the project.
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Elastogenic characterization of rat BM-MSC-derived SMCS towards use in soft Tissue EngineeringWintrich, Sahithya 07 November 2012 (has links)
No description available.
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A parallel version of the preconditioned conjugate gradient method for boundary element equationsPester, M., Rjasanow, S. 30 October 1998 (has links)
The parallel version of precondition techniques is developed for
matrices arising from the Galerkin boundary element method for
two-dimensional domains with Dirichlet boundary conditions.
Results were obtained for implementations on a transputer network
as well as on an nCUBE-2 parallel computer showing that iterative
solution methods are very well suited for a MIMD computer. A
comparison of numerical results for iterative and direct solution
methods is presented and underlines the superiority of iterative
methods for large systems.
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Automatic Sampling with the Ratio-of-uniforms MethodLeydold, Josef January 1999 (has links) (PDF)
Applying the ratio-of-uniforms method for generating random variates results in very efficient, fast and easy to implement algorithms. However parameters for every particular type of density must be precalculated analytically. In this paper we show, that the ratio-of-uniforms method is also useful for the design of a black-box algorithm suitable for a large class of distributions, including all with log-concave densities. Using polygonal envelopes and squeezes results in an algorithm that is extremely fast. In opposition to any other ratio-of-uniforms algorithm the expected number of uniform random numbers is less than two. Furthermore we show that this method is in some sense equivalent to transformed density rejection. (author's abstract) / Series: Preprint Series / Department of Applied Statistics and Data Processing
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Realization and comparison of various mesh refinement strategies near edgesApel, T., Milde, F. 30 October 1998 (has links) (PDF)
This paper is concerned with mesh refinement techniques for
treating elliptic boundary value problems in domains with re-
entrant edges and corners, and focuses on numerical experiments.
After a section about the model problem and discretization
strategies, their realization in the experimental code FEMPS3D is
described. For two representative examples the numerically
determined error norms are recorded, and various mesh refinement
strategies are compared.
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Tauextrapolation - theoretische Grundlagen, numerische Experimente und Anwendungen auf die Navier-Stokes-GleichungenBernert, K. 30 October 1998 (has links)
The paper deals with tau-extrapolation - a modification of the
multigrid method, which leads to solutions with an improved con-
vergence order. The number of numerical operations depends
linearly on the problem size and is not much higher than for a
multigrid method without this modification. The paper starts
with a short mathematical foundation of the tau-extrapolation.
Then follows a careful tuning of some multigrid components
necessary for a successful application of tau-extrapolation. The
next part of the paper presents numerical illustrations to the
theoretical investigations for one- dimensional test problems.
Finally some experience with the use of tau-extrapolation for the
Navier-Stokes equations is given.
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Anisotropic mesh refinement in stabilized Galerkin methodsApel, Thomas, Lube, Gert 30 October 1998 (has links)
The numerical solution of the convection-diffusion-reaction problem is considered in two and three dimensions. A stabilized finite element method of Galerkin/Least squares type accomodates diffusion-dominated as well as convection- and/or reaction- dominated situations. The resolution of boundary layers occuring in the singularly perturbed case is accomplished using anisotropic mesh refinement in boundary layer regions. In this paper, the standard analysis of the stabilized Galerkin method on isotropic meshes is extended to more general meshes with boundary layer refinement. Simplicial Lagrangian elements of arbitrary order are used.
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Parallelization of multi-grid methods based on domain decomposition ideasJung, M. 30 October 1998 (has links)
In the paper, the parallelization of multi-grid methods for solving second-order elliptic boundary value problems in two-dimensional domains is discussed. The parallelization strategy is based on a non-overlapping domain decomposition data structure such that the algorithm is well-suited for an implementation on a parallel machine with MIMD architecture. For getting an algorithm with a good paral- lel performance it is necessary to have as few communication as possible between the processors. In our implementation, communication is only needed within the smoothing procedures and the coarse-grid solver. The interpolation and restriction procedures can be performed without any communication. New variants of smoothers of Gauss-Seidel type having the same communication cost as Jacobi smoothers are presented. For solving the coarse-grid systems iterative methods are proposed that are applied to the corresponding Schur complement system. Three numerical examples, namely a Poisson equation, a magnetic field problem, and a plane linear elasticity problem, demonstrate the efficiency of the parallel multi- grid algorithm.
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Anisotropic mesh refinement for singularly perturbed reaction diffusion problemsApel, Th., Lube, G. 30 October 1998 (has links)
The paper is concerned with the finite element resolution of layers appearing
in singularly perturbed problems. A special anisotropic grid of Shishkin type
is constructed for reaction diffusion problems. Estimates of the finite element
error in the energy norm are derived for two methods, namely the standard
Galerkin method and a stabilized Galerkin method. The estimates are uniformly
valid with respect to the (small) diffusion parameter. One ingredient is a
pointwise description of derivatives of the continuous solution. A numerical
example supports the result.
Another key ingredient for the error analysis is a refined estimate for
(higher) derivatives of the interpolation error. The assumptions on admissible
anisotropic finite elements are formulated in terms of geometrical conditions
for triangles and tetrahedra. The application of these estimates is not
restricted to the special problem considered in this paper.
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