Catálogo de publicaciones - libros

Wave propagation over long distances is usually modeled numerically by high order finite difference schemes, compact schemes or spectral methods. The schemes need good wave propagation properties, i.e. low dispersion and low dissipation. In this paper we show that finite volume schemes may be a good alternative with a number of nice properties. The so called ADER schemes of arbitrary accuracy have been first proposed by Toro et. al. for conservation laws as high order extension of the shock-capturing schemes. In this paper we show theoretically and numerically their dispersion and dissipation properties using the method of differential approximation of Shokin. In two dimensions the stability of these ADER schemes is investigated numerically with the von Neumann method. Numerical results and convergence rates of ADER schemes up to 16th order of accuracy in space and time are shown and compared with respect to the computational effort.

Several new possibilities to enhance information capacity of data transmission by integration of several key technologies such as dispersion management, wavelength-division multiplexing and optical regeneration of signals are discussed. Mathematical modelling results may be used for upgrade of existing fiber links and design of new generation of long-haul high-bit-rate communication lines.

This paper describes a case study which deals with the analysis of scalability properties on modern parallel computer architectures in light of a CFD related problem – the scalable parallel adaption of unstructured grids. It shows how state-ofthe- art benchmarking, profiling, and tracing tools can assist authors of parallel CFD applications in making the right design and implementation decisions regarding scalable application performance. A sophisticated platform evaluation framework and a distributed parallel program analyzer are presented.

The problem on vertical electrical sounding above the embedding with two-dimensional geometry of heterogeneity is considered. The conditions of convergence of the iterative method for solving the charge density equation are obtained.

Vector processors are invaluable tools for high performance numerical simulations due to their high sustained performance. The high efficiency can be attributed to a superior balance between peak performance of the arithmetic pipelines and memory bandwidth. In the Teraflop-Workbench project HLRS and NEC investigate how to sustain this performance for HLRS applications.We report first results of this cooperation.

Image fusion or registration is central to many challenges in medical imaging today and has a vast range of applications. The purpose of this paper is to give an introduction to intensity based non-linear registration and fusion problems from a variational point of view. To do so, we review some of the most promising non-linear registration strategies currently used in medical imaging and show that all these techniques may be phrased in terms of a variational problem and allow for a unified treatment.

The parametrical analysis of stressed-deformed state of multilayered reinforced nodoid shells on a basis of geometrically linear and nonlinear variants of classical and non-classical theories is made. Influence of structure of reinforcement of a composite material, cross shift of binding and an order of arrangement of the reinforced layers on behaviour of shells is investigated. Comparison of the numerical solutions received by the methods of spline-collocation and discrete orthogonalization is conducted. High efficiency of used numerical methods is shown at the solution boundary value problem for stiff systems of the differential equations.

For a given draft tube geometry numerical flow simulations have been carried out. Equivalent to part load operation of a Turbine with fixed runner blades such as Francis- or Propellerturbines a set of different inlet boundary conditions have been specified to simulate the draft tube vortex. The intention was to find out some correlation between inlet condition and the draft tube vortex structure. The results can be essential for design purposes in turbine engineering.

The purpose of a GRID environment construction for scientific GIS problems is considered. The environment is based on parallel computing, centralized warehousing, and decentralized resource control. Some examples of parallel computing are also shown.

The feasibility of particle based simulation methods is shown for powder technological applications like compaction, sintering and filling of a dispersed powder. In contrast to continuum methods this approach automatically takes into account the rearrangements of the grains and predicts structural composition. This allows for a comparison with analytical results in the case of powder compaction and sintering giving new insights into the dynamics of granular materials.