Tobias Gradl

Learn More
The hierarchical hybrid grid framework supports the parallel implementation of multigrid solvers for finite element problems. Specifically, it generates extremely fine meshes by using a structured refinement of an unstructured base mesh. For special problems with piecewise uniform material parameters, this leads to the possibility of stencil-based(More)
While multicore architectures are becoming usual on desktop machines, supercomputers are approaching million cores. The amount of memory and compute power on current clusters enable us e.g. to obtain a resolution of in excess (10 000)=10 degrees of freedom. However, on the downside we are forced to partition our domain into extremely many sub-problems.(More)
Making multigrid algorithms run efficiently on large parallel computers is a challenge. Without clever data structures the communication overhead will lead to an unacceptable performance drop when using thousands of processors. We show that with a good implementation it is possible to solve a linear system with 10 unknowns in about 1.5 minutes on almost(More)
In this paper a local Fourier analysis for multigrid methods on tetrahedral grids is presented. Different smoothers for the discretization of the Laplace operator by linear finite elements on such grids are analyzed. A four-color smoother is presented as an efficient choice for regular tetrahedral grids, whereas line and plane relaxations are needed for(More)
Quantum control plays a key role in quantum technology, e.g. for steering quantum hardware systems, spectrometers or superconducting solid-state devices. In terms of computation, quantum systems provide a unique potential for coherent parallelisation that may exponentially speed up algorithms as in Shor’s prime factorisation. Translating quantum software(More)
Multigrid methods are among the most efficient and widespread methods for solving large linear systems of equations that arise, for example, from the discretization of partial differential equations. In this paper we introduce a new approach for optimizing the computational cost of the full multigrid method to achieve a given accuracy by determining the(More)
Complement-dependent gliotoxic antibody activity was determined in 22 patients with multiple sclerosis (MS) and 19 normal control persons. Peripheral blood serum was collected from MS patients at about 4-week intervals for one year, and the results of cytotoxicity tests correlated with the course of disease. For 10 MS patients with stable disease,(More)
Midcycle cerevical mucus samples from 20 fertile women with negative, and from 6 infertile women with positive serum-sperm agglutinating activity were subjected to a qualitative protein analysis by the Ouchterlony-technique, to polyacrylamide (PAA) discelectrophoresis and after purification on spermatozoa they were also run against rabbit antihuman serum in(More)
The total amount of humoral sperm antibody protein is determined following its isolation by affinity-chromatography on spermatozoa. Serum proteins are eluted by Sorensen phosphate buffer. Antibodies attached to spermatozoa suspended in Sephadex G 75 columns resist elution by Sorensen buffer. They can be quantitatively washed out by 8 ml Tris HCl-buffer pH(More)
In a 1 year longitudinal study of twenty-two patients with multiple sclerosis (MS) and twenty-one normal control subjects, peripheral blood leucocytes were stimulated with lipoplysaccharide (LPS), a B cell mitogen, and phytohaemagglutinin (PHA) a T cell mitogen. EA- and EAC-rosette formation was also performed to assay null and B cells respectively, and the(More)