Gabriel Wittum – författare

The GAMM Committee for "Efficient Numerical Methods for Partial Differential Equations" organizes seminars and workshops on subjects concerning the algorithmic treatment of partial differential equations. The topics are discretisation methods like the finite element and the boundary element method for various type of applications in structural and fluid mechanics. Particular attention is devoted to the advanced solution methods. The series of such seminars was continued in 1995, January 20-22, with the 11th Kiel-Seminar on the special topic Numerical Treatment of Coupled Systems at the Christian-Albrechts-University of Kiel. The seminar was attended by 100 scientist from 9 countries. 23 lectures were given, including two survey lectures. Different kinds of couplings are considered in this volume. The coupling of different components may occur in the physical model. On the other hand, a coupling of subsystems can be generated by the numerical solution technique. General examples of the latter kind are the domain decomposition (see p. 128) or subspace decomposition (p. 117). The local defect correction method couples different discretizations of the same problem in order to improve the results, although the basic linear system to be solved remains unchanged (p. 47). In general, the aim of the numerical coupling is to make use of (efficient) subsystem solvers (p. 1). The combination of different discretization techniques is mentioned on page 59.

This volume contains 20 contributions to the 1st GAMM-Seminar at ICA Stuttgart, which was held in Stuttgart, October 12 - 13, 1995. In the field of environmental sciences, numerical procedures for the simulation of ecological problems are growing increasingly topical. The solution of typical problems in environmental research is closely connected with numerical supercomputing. The main subject of the seminar was the modeling and numerical simulation of ground water and soil water. Further topics were multi-scale modeling, special discretization schemes, adaptivity, multi-grid methods, heterogenity, parameter identification, homogenization, density driven groundwater flow, and coupling of transport and chemistry.

The GAMM Committee for "Efficient Numerical Methods for Partial Differential Equations" organizes seminars and workshops on subjects concerning the algorithmic treatment of partial differential equations. The topics are discretisation methods like the finite element and the boundary element method for various type of applications in struc­ tural and fluid mechanics. Particular attention is devoted to advanced solution method". The latest seminar in this series was the 12th Kiel-Seminar which took place on January 19-21, 1996 at Christian-Albrechts-University of Kiel and focussed on the topic Boundary Elements: Implementation and Analysis of Advanced Algorithms. The seminar was attended by 65 scientists from 10 countries. 23 lectures were given, including two survey lectures. In the last years, a remarkable progress in the numerical treatment of boundary de­ ment methods (BEM) has been obtained in Germany. This is, in particular, a res~I1t of a Schwerpunktverfahren supported by the DFG. Many aspects of the BEM are not ouly analysed but also implemented. Therefore, these proceedings present a number of papers on implementational aspects besides the analysis of advanced techniques.

Dieser Sammelband enthält die ausgearbeiteten Fassungen einiger Beiträge zu einem Workshop über "Numerische Algorithmen auf Transputer-Systemen", welcher im Rahmen der Aktivitäten zweier GAMM-Fachausschüsse am 31. 5. - 1. 6. 1991 in Heidelberg stattfand. Die etwa 120 Teilnehmer aus Mathematik, Physik, Informatik und den Ingenieurwissenschaften diskutierten theoretische und praktische Aspekte des Entwurfs und der Realisierung von numerischen Al­ gorithmen vornehmlich auf Transputer-basierten Parallelrechnern. Die starke Rolle der Transputer-Systeme spiegelte deren große Verbreitung an Hochschul­ instituten wieder. Seit Anfang 1990 wurden in der Bundesrepublik mehrere größere Parallelrechner dieser Art mit bis zu 320 Prozessoren installiert. Dazu kommen noch eine Vielzahl kleiner Entwicklungssysteme bis hinunter zu ein­ zelnen Transputer-Boards in Tischrechnern. Dies hat zu einem weitverbreite­ ten Interesse an den mit der Transputer-Technologie verbundenen Hard- und Software-Fragen geführt. Die Präsenz der anderen Parallelrechnertypen vor­ nehmlich US-amerikanischer Herkunft blieb dagegen auf relativ wenige Instal­ lationen in größeren Instituten und Rechenzentren beschränkt. Im Zuge der breiteren Verfügbarkeit von Parallelrechnern aller Größenordnun­ gen befaßt sich eine zunehmende Zahl von Arbeitsgruppen an Universitäten und in außeruniversitären Forschungseinrichtungen mit der Entwicklung von parallelen Algorithmen und deren Anwendung für wissenschaftliche und tech­ nische Problemstellungen. Diese Entwicklung folgt dem internationalen Trend im wissenschaftlichen Rechnen hin zur Nutzung von Mehrprozessorsystemen zur Steigerung der numerischen Rechenleistung. Da abzusehen ist, daß die kommenden Hochleistungsrechner wohl durchgehendparallele Architekturen haben werden, ist es wichtig, bereits frühzeitig möglichst viele Erfahrungen mit der Parallelisierung von Algorithmen und ihrer Implementierung zu sammeln.

This volume contains 22 papers presented at the Kiel Seminar in 1992. The Kiel Seminars are well known, and cover special areas in numerical methods for partial differential equations, numerical linear algebra, numerical methods for integral equations and related areas. The papers cover a broad range of topics from mathematical theory to practical applications of incomplete decompositions as smoothers in multi-grid methods, as preconditioners for conjugate gradient-type methods and the use of ILU for systems of partial differential equations.

This volume contains 23 contributions to the 10th GAMM-Seminar, which was held in Kiel on the 14-16 of January 1994. The central topics are advanced numerical techniques for solving flow problems. The Navier-Stokes equations are discussed with respect to anisotropically refined meshes, in combination with non-equilibrium chemistry and with respect to implicit time-discretizations and parallel solvers. Furthermore, robust multi-grid methods are described for this problem. Five papers are devoted to parallel algorithms, and a further one to domain decomposition techniques. The very important aspect of adaptive strategies is considered in several contributions, including a discussion of appropriate error estimators. Other subjects are the FEM-BEM coupling, convection-dominated systems, unstructured grid techniques and complex geometries in 3-D.

This is the first book that deals systematically with the numerical solution of elliptic partial differential equations by their reduction to the interface via the Schur complement. Inheriting the beneficial features of finite element, boundary element and domain decomposition methods, our approach permits solving iteratively the Schur complement equation with linear-logarithmic cost in the number of the interface degrees of freedom. The book presents the detailed analysis of the efficient data-sparse approximation techniques to the nonlocal Poincare-Steklov interface operators associated with the Laplace, biharmonic, Stokes and Lame equations. Another attractive topic are the robust preconditioning methods for elliptic equations with highly jumping, anisotropic coefficients. A special feature of the book is a unified presentation of the traditional iterative substructuring and multilevel methods combined with modern matrix compression techniques applied to the Schur complement on the interface.

This volume contains a selection from the papers presented at the Fifth European Multigrid Conference, held in Stuttgart, October 1-4, 1996. There were 88 registered participants from 14 different countries worldwide, and 65 lectures were given. Earlier European Multigrid Conferences were held in Cologne in 1981 and 1985, in Bonn in 1990, and in Amsterdam in 1993. The next European Conference is planned in 1999 in Gent. The European Multigrid Conference '96 was organized by the Institut fUr Computer- anwendungen (ICA) of Stuttgart University, in cooperation with the GAMM Com- mittee for "Scientific Computing", SFB 359 and 404 and the research network WiR Ba- Wii. The list of topics contained lectures on Multigrid Methods: robustness, adaptivity, wavelets, parallelization, application in computational fluid dynamics, porous media flow, optimisation and computational mechanics. A considerable part of the talks fo- cused on algebraic multigrid methods. The remaining contributions will be published by the Institut fUr Computeranwen- dungen (ICA) in Stuttgart in a special ICA report. Special thanks are due to Oktavia Klassen, who carefully compiled the contributions to this volume.

This book presents the state-of-the-art in simulation on supercomputers. Leading researchers present results achieved on systems of the Gauss-Allianz, the association of High-Performance Computing centers in Germany. The reports cover all fields of computational science and engineering, ranging from CFD to Computational Physics and Biology to Computer Science, with a special emphasis on industrially relevant applications. Presenting results for large-scale parallel microprocessor-based systems and GPU and FPGA-supported systems, the book makes it possible to compare the performance levels and usability of various architectures. Its outstanding results in achieving the highest performance for production codes are of particular interest for both scientists and engineers. The book includes a wealth of color illustrations and tables.

This book presents the state-of-the-art in simulation on supercomputers. Leading researchers present results achieved on systems of the Gauss-Allianz, the association of High-Performance Computing centers in Germany. The reports cover all fields of computational science and engineering, ranging from CFD to Computational Physics and Biology to Computer Science, with a special emphasis on industrially relevant applications. Presenting results for large-scale parallel microprocessor-based systems and GPU and FPGA-supported systems, the book makes it possible to compare the performance levels and usability of various architectures. Its outstanding results in achieving the highest performance for production codes are of particular interest for both scientists and engineers. The book includes a wealth of color illustrations and tables.

While information and communication technology has a vast influence on our lives, little is understood about its effects on the way we learn. In the Age of Information, students – consciously or not – are learning in diverse formal and informal environments from a broad variety of sources, with scientific knowledge competing against unfounded assertions, and misinformation and biased data spreading through social and mass media. The Positive Learning in the Age of Information (PLATO) program illustrated by the contributions in this book unites outstanding and highly innovative expertise on the fundamentals of information processing and human learning to investigate a new paradigm of positive learning as a vital, morally and ethically oriented approach, which is of existential importance to maintaining the civilization standards of a modern society in the digital age.