TY - GEN A1 - Melenk, Herbert T1 - The Complexity Barrier in REDUCE - a Case Study. N2 - The power of the symbolic math system {\small REDUCE} for solving large and difficult problems in science and engineering is demonstrated by a set of model problems. These include algebraic equation solving, formal variable elimination, formal power series, symbolic treatment of differential equations and applications from theoretical physics. T3 - ZIB-Report - TR-94-06 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5119 ER - TY - GEN A1 - Dalitz, Wolfgang A1 - Grötschel, Martin A1 - Lügger, Joachim A1 - Sperber, Wolfram T1 - Neue Perspektiven eines verteilten Informationssystems für die Mathematik. N2 - Die Kombination von elektronischer Fachinformation mit den neuen Mitteln der Kommunikation eröffnet neue Perspektiven für die Mathematik in Deutschland. Aufbauend auf das laufende, BMFT-geförderte Projekt ``Fachinformation'' der Deutschen Mathematiker-Vereinigung (DMV) plant die DMV eine Querschnittsaktivität für die Mathematik. Diese soll nicht nur die mathematischen Fachbereiche und Forschungsinstitute einbeziehen, sondern auch mathematische Forschungslabors aus der Industrie und die Informationsversorger der Mathematik, insbesondere die wissenschaftlichen Verlage, die TIB Hannover, die Bibliotheken der Universitäten und \mbox{-- nicht zuletzt --} das FIZ Karlsruhe mit dem Zentralblatt für Mathematik. \noindent Auf der technischen Grundlage des Internet und seiner weltweit verbreiteten Informationsdienste (Gopher, WAIS, WorldWideWeb, Hyper-G, ftp und E-mail) soll ein verteiltes, mathematisches Informationssystem geschaffen werden, bei dem die Partner des gemeinsamen Vorhabens ihre örtlichen Ressourcen untereinander und zugleich weltweit verfügbar machen. Diese Ziele sind durch konsequenten Einsatz von Software erreichbar, die nach dem Client-Server-Modell strukturiert und die im Internet verbreitet bzw.~anerkannt ist. \noindent Die Bereitstellung von Technik reicht keineswegs aus. Ohne die Schaffung einer personellen, organisatorischen und technischen Infrastruktur ist die Durchführung eines solchen Projekts nicht möglich. Als Massnahmen sind - für alle Partner - geplant: \hspace*{2mm} * Schaffung der Funktion des Informationsbeauftragten \hspace*{2mm} * Einrichtung eines gemeinsamen ``Forums für mathematische Information'' \hspace*{2mm} * Errichtung und Betreuung von mathematischen Informationsstationen \hspace*{2mm} * Teilnahme an nationalen und internationalen Standardisierungsmassnahmen \hspace*{2mm} * Workshops und regelmässige Schulungen, Öffentlichkeitsarbeit \noindent Als Aktivitäten - mit Focus auf mathematische Fachinformation - sind folgende Teilaufgaben und Pilotvorhaben bei allen Partnern geplant: \hspace*{2mm} * Einrichtung von elektronischen Informationssystemen \hspace*{2mm} * Verteiltes elektronisches Angebot von Preprints und Skripten (Volltexte) \hspace*{2mm} * Verteiltes elektronisches Angebot von Software- und Datensammlungen \hspace*{2mm} * Zugriff auf globale Informationssysteme in der Mathematik \hspace*{2mm} * Organisation eines Lebenden Mathematischen Museums \hspace*{2mm} * Zugriff auf elektronische Kataloge von Bibliotheken, insbesondere Fachbereichsbibliotheken \hspace*{2mm} * Schaffung eines organisatorischen Rahmens für elektronische mathematische Journale \hspace*{2mm} * Elektronisches Angebot von eingescannten historischen Dokumenten und Büchern \hspace*{2mm} * Schaffung einer Organisationsform für elektronisches Reviewing \hspace*{2mm} * Erprobung von Verfahren zur elektronischen Lieferung von Dokumenten \hspace*{2mm} * Elektronische Projektorganisation \noindent Das Vorhaben zielt ab auf die Schaffung einer informationstechnischen Infrastruktur für Datenbank-Retrieval, E-mail, ``Electronic Conferencing'' und fachspezifische Informationsnetze in exemplarischer Form für Wissenschaft und Industrie - auch für andere Fachgebiete. T3 - ZIB-Report - TR-94-07 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5122 ER - TY - GEN A1 - Dalitz, Wolfgang A1 - Grötschel, Martin A1 - Lügger, Joachim A1 - Sperber, Wolfram T1 - New Perspectives of a Distributed Information System for Mathematics. N2 - \begin{footnotesize} \noindent Combining electronic specialized information, such as electronic information retrieval from central databases, with the new means of communication opens up new perspectives for mathematics in Germany. Based on the current Fachinformationsprojekt (Specialized Information Project) run by the Deutsche Mathematiker-Vereinigung (DMV) and supported by the Federal Minister for Research and Technology (BMFT), the DMV is planning a new infrastructure activity for mathematics. This activity will not only include mathematical university departments and research institutes, but also partners from mathematical research laboratories in industry as well as suppliers of mathematical information, in particular, scientific publishing houses, the Technical Information Library (TIB) Hannover, university libraries and -- last but not least -- the Fachinformationszentrum (FIZ) Karlsruhe with the Zentralblatt für Mathematik. \noindent On the technical basis of the Internet and its worldwide information services (Gopher, WAIS, World Wide Web, Hyper-G, ftp and e-mail), a distributed mathematical information system is to be created, whose partners make their local resources available both to other partners and to the worldwide Internet community. These aims can be achieved by means of the consequent use of software that is structured according to the client-server model and distributed and accepted within the Internet. \noindent Providing the technical equipment, however, is by far not enough. Without the creation of a personal, technical and organizational infrastructure, realization of such a project will not be possible. For every partner the realization of the following measures is envisaged:\\[-7mm] \noindent \end{footnotesize} \begin{small} \begin{itemize} \item[*] Establishing an Information Coordinator\/ at every participating institution\\[-8mm] \item[*] Creation of a Forum for Mathematical Information\/\\[-8mm] \item[*] Installation and maintenance of Mathematical Information Stations\/\\[-8mm] \item[*] Participation in national and international Standardization Activities\/\\[-8mm] \item[*] Regular workshops and training courses, public relations\\[-7mm] \end{itemize} \noindent The following activities (carried out by all partners or within pilot projects by special groups) focusing on mathematical and mathematics-related information are planned:\\[-7mm] \noindent \begin{itemize} \item[*] Set up of Electronic Information Systems\/ by all partners \\[-8mm] \item[*] Distributed\/ electronic offer of Preprints\/ and scripts (full texts) by all partners\\[-8mm] \item[*] Distributed\/ electronic offer of Software and Data Collections\/ by all partners\\[-8mm] \item[*] Access to Global Information Systems in Mathematics\/\\[-8mm] \item[*] Organization of a Living Museum of Mathematics\/\\[-8mm] \item[*] Access to {\it Electronic Library Catalogs,}\/ esp.~to libraries of university departments\\[-8mm] \item[*] Electronic offer of Scanned Historical Books and Documents\/\\[-8mm] \item[*] Creation and management of Electronic Mathematical Journals\/\\[-8mm] \item[*] Creation of a framework for various kinds of Electronic Reviewing\/\\[-8mm] \item[*] Testing of new methods for Electronic Document Delivery\/\\[-8mm] \item[*] Electronic Project Organization\/\\[-7mm] \end{itemize} \noindent \end{small} \begin{footnotesize} The project aims, at its beginning, at the creation of an information infrastructure for database retrieval, e-mail, electronic conferencing and subject-specific information networks. Its focus is on mathematics in Germany. The general scope, however, is broader. The project is open for discussion, coordination, and cooperation with partners in other areas of science, industry or in other countries. It is also hoped that this project may form an example along which other models of electronic information and communication can be developed. Moreover, the project is also meant to enhance the offer from German mathematics to the worldwide "give and take" within the Internet community. \end{footnotesize} T3 - ZIB-Report - TR-94-08 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5139 ER - TY - GEN A1 - Koepf, Wolfram T1 - REDUCE Package for the Indefinite and Definite Summation N2 - This article describes the REDUCE package ZEILBERG implemented by Gregor Stölting and the author. The REDUCE package ZEILBERG is a careful implementation of the Gosper (The sum package contains also a partial implementation of the Gosper algorithm.) and Zeilberger algorithms for indefinite, and definite summation of hypergeometric terms, respectively. An expression $a_k$ is called a {\sl hypergeometric term} (or {\sl closed form}), if $a_{k}/a_{k-1}$ is a rational function with respect to $k$. Typical hypergeometric terms are ratios of products of powers, factorials, $\Gamma$ function terms, binomial coefficients, and shifted factorials (Pochhammer symbols) that are integer-linear in their arguments. T3 - ZIB-Report - TR-94-09 Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5147 ER - TY - GEN A1 - Zuse, Konrad T1 - Discrete Mathematics and Rechnender Raum (Computing Space) -Part 1-. Cellular Structured Space (Rechnender Raum) and Physical Phenomena -Part 2-. N2 - The first part of the report contains a lecture presented at ``Scientific Computing in der Theoretischen Physik'', a workshop organized by the DMV-Fachgruppe Scientific Computing in cooperation with the GAMM-Fachauschuß Scientific Computing at Freie Universit{ä}t Berlin in March 1994. To complete this lecture, a slightly modified version of TR 93-12 is appended. T3 - ZIB-Report - TR-94-10 Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5156 ER - TY - GEN A1 - Grötschel, Martin A1 - Lügger, Joachim T1 - Wissenschaftliche Kommunikation am Wendepunkt - Bibliotheken im Zeitalter globaler elektronischer Netze - N2 - Durch extrem steigende Preise für traditionelle wissenschaftliche Zeitschriften bei gleichzeitiger Stagnation der Bibliotheksetats an den Hochschulen und bei weltweit weiterhin anwachsenden Forschungsleistungen ist die adäquate Versorgung der Wissenschaften mit relevanter Literatur gefährdet. Dokumentenliefersysteme werden vielerorts als Lösung dieser ``Bibliothekskrise'' propagiert. Dieser Weg ist für den derzeitigen Literaturversorgungsmarkt sinnvoll, aber er bietet keine langfristig stabile Lösung. Wenn die Grundversorgung der Bibliotheken weiter schrumpft, wird Dokumentenlieferung in der zur Zeit üblichen bzw. geplanten Form die Kosten nur noch zusätzlich in die Höhe treiben. Wir plädieren in diesem Aufsatz für einen grundsätzlich neuen Ansatz. Wir sind der Meinung, da\ss{} einzig der Übergang auf elektronische Medien eine bezahlbare, umfassende und benutzerfreundliche Versorgung der Wissenschaftler mit Literatur sichern kann. Wir zeigen -- unter anderem anhand elektronischer Zeitschriften -- wie zum Beispiel durch Kooperation von Bibliotheken mit Fachbereichen und wissenschaftlichen Gesellschaften neue Wege der Informationsversorgung beschritten werden können. Dieser Vorschlag einer neuen Organisation des wissenschaftlichen Publikationswesen erfordert Umdenken in vielen Bereichen. Neue Organisationsformen sind erforderlich, Rechte müssen anders verteilt, Aufgaben auf andere Schultern geladen werden. Die Bibliotheken werden besonders betroffen sein. Aber für sie ist die konsequente Nutzung der sich rasch ausbreitenden Informationstechnik (darunter verstehen wir u. a. globale elektronische Netze, leistungsfähige Rechner, kostengünstige Speichermedien, benutzerfreundliche Such- und Retrieval-Systeme, Entwicklung weltweit akzeptierter Datenformate) eine wirkliche und möglicherweise die einzige Chance, ihrem Auftrag zur umfassenden Versorgung der Wissenschaften mit Literatur zu gesamtwirtschaftlich niedrigen Kosten weiterhin nachzukommen. Au\ss{}erdem bietet die Bereitstellung und Archivierung wissenschaftlicher Literatur auf elektronischem Wege bedeutende Vorteile gegenüber der traditionellen Dokumentation auf Papier, die im übrigen, falls erwünscht, weiterhin betrieben werden kann. T3 - ZIB-Report - TR-95-01 Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5164 ER - TY - GEN A1 - Hege, Hans-Christian A1 - Polthier, Konrad T1 - Visualization and Mathematics. International Workshop N2 - International Workshop with support of the Deutsche Forschungsgemeinschaft (DFG) and Max-Planck-Gesellschaft (MPG) Berlin (Dahlem), Germany, May 30 - June 2, 1995 T3 - ZIB-Report - TR-95-02 Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5179 ER - TY - GEN A1 - Koepf, Wolfram T1 - REDUCE Packages on Power Series, Z-Transformation, Residues and Trigonometric Simplification N2 - In this report, we present a collection of new REDUCE packages that recently have been developed. These are the packages {\tt FPS}, {\tt ZTRANS}, {\tt RESIDUE} and {\tt TRIGSIMP} on the following topics: \begin{itemize} \item[] FPS Calculation of differential equations and formal power series representations, in particular for orthogonal polynomials and special functions of the hypergeometric type. \item[] ZTRANS Calculation of the Z-Transformation and its inverse. % to be used for the solution of linear recurrence equations. \item[] RESIDUE Calculation of residues of meromorphic functions. \item[] TRIGSIMP Simplification of expressions involving trigonometric and hyperbolic functions. \end{itemize} % These packages can be obtained via anonymous {\tt ftp} from % {\tt } in the directories {\tt ..}, ) For each of these packages, a description in form of a \LaTeX\ file is distributed together with the package. These documentations are collected here. In a final chapter, we show how to solve some difficult problems with these packages, and how they usefully can be combined. T3 - ZIB-Report - TR-95-03 Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5187 ER - TY - GEN A1 - Beck, Rudolf A1 - Erdmann, Bodo A1 - Roitzsch, Rainer T1 - KASKADE 3.0 - An Object Oriented Adaptive Finite Element Code N2 - KASKADE 3.0 was developed for the solution of partial differential equations in one, two, or three space dimensions. Its object-oriented implementation concept is based on the programming language C++$\,$.~Adaptive finite element techniques are employed to provide solution procedures of optimal computational complexity. This implies a posteriori error estimation, local mesh refinement and multilevel preconditioning. The program was designed both as a platform for further developments of adaptive multilevel codes and as a tool to tackle practical problems. Up to now we have implemented scalar problem types like stationary or transient heat conduction. The latter one is solved with the Rothe method, enabling adaptivity both in space and time. Some nonlinear phenomena like obstacle problems or two-phase Stefan problems are incorporated as well. Extensions to vector-valued functions and complex arithmetic are provided. %Such free boundary problems ... We have implemented several iterative solvers for both symmetric and unsymmetric systems together with multiplicative and additive multilevel preconditioners. Systems arising from the nonlinear problems can be solved with lately developed monotone multigrid methods. %An object-oriented concept was chosen for KASKADE~3.0, based on the programming %language C++$\,$. This should provide the desired extensibilty and clearly %reflect the structure of the code. %A direct sparse matrix solver (Harwell MA28) is included. T3 - ZIB-Report - TR-95-04 Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5199 ER - TY - GEN A1 - Busch, Hubert A1 - Schulz, Sandra A1 - Kroß, Günther T1 - Aufbau des Berliner Breitbandnetzes für die Wissenschaft N2 - Seit 1991 verfolgt die Berliner Wissenschaft verstärkt das Ziel, ihre Einrichtungen untereinander breitbandig mit Transferraten oberhalb von 34 Mb/s in Glasfasertechnik zu vernetzen. Im ersten Halbjahr 1995 ist es gelungen, die erste Stufe des Berliner Breitbandnetzes für die Wissenschaft ({\it Berlin Research Area Information Network - BRAIN}) aufzubauen. Dieser Bericht beschreibt die verschiedenen Phasen der Vernetzung der Wissenschaftseinrichtungen Berlins von den Anfängen im Jahre 1975 über die Planungen zum Breitbandnetz ab 1991 und die Realisierungsschritte durch die erfolgreiche Zusammenarbeit mit dem Landesamt für Informationstechnik Berlin (LIT) insbesondere bei der Verwendung von Glasfaserleitungen des Landes. Weiterhin werden der Aufbau des Berlin Regional Testbed in seiner Realisierung einschliesslich seiner Anwendungsprojekte mit Stand Juni 1995 und sodann die Pläne der Berliner Wissenschaftseinrichtungen für die zukünftige breitbandige Vernetzung einer Vielzahl von Standorten als allumfassendes Berlin Research Area Information Network dargestellt. T3 - ZIB-Report - TR-95-05 Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5207 ER - TY - GEN A1 - Weber, Marcus A1 - Meyer, Holger T1 - ZIBgridfree - Adaptive Conformation Analysis with qualified Support of Transition States and Thermodynamic Weights N2 - This paper introduces a new algorithm of conformational analysis based on mesh-free methods as described in [M. Weber. Mehless methods in Conformation Dynamics.(2005)]. The adaptive decomposition of the conformational space by softly limiting functions avoids trapping effects and allows adaptive refinement strategies. These properties of the algorithm makes ZIBgridfree particularly suitable for the complete exploration of high-dimensional conformational space. The adaptive control of the algorithm benefits from the tight integration of molecular simulation and conformational analysis. An emphasized part of the analysis is the Robust Perron Cluster Analysis (PCCA+) based on the work of Peter Deuflhard and Marcus Weber. PCCA+ supports an almost-characteristic cluster definition with an outstanding mapping of transition states. The outcome is expressed by the metastable sets of conformations, their thermodynamic weights and flexibility. T3 - ZIB-Report - 05-17 KW - Molecular Dynamics KW - Meshfree Methods KW - Conformation Analysis KW - Quality Functions Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-8514 ER - TY - GEN A1 - Lügger, Joachim T1 - Über Suchmaschinen, Verbünde und die Integration von Informationsangeboten N2 - Die Entwicklung einer bibliothekarischen Suchmaschine ist das technisch-organisatorische Herztück des Kooperativen Bibliotheksverbundes Berlin-Brandenburg (KOBV). Auf dem Wege über diese Innovation verfolgen die Länder Berlin und Brandenburg und ihre Bibliotheken das Ziel, ihr Bibliothekswesen zu erneuern und zu reorganisieren. Die Entwicklung der Suchmaschine ist für die Partner im KOBV-Projekt kein Selbstzweck, sondern nur Mittel zum Zweck - insbesondere, um die heterogene Welt der in Berlin und in Brandenburg eingesetzten integrierten Bibliotheksinformationssysteme harmonisch miteinender zu verbinden. Mit der KOBV-Suchmaschine sind informationstechnische Sichtweisen und Methoden entstanden, die sich potentiell auch auf die überregionale Arbeit des KOBV auswirken können und in Kooperation mit den Bibliotheksverbänden auf die Zusammenarbeit der Verbünde insgesamt. Der Artikel konzentriert sich am Beispiel der KOBV-Such¡ma¡schine auch auf diesen Aspekt. Auf die Bibliotheken kommen mit dem Internet und dem World Wide Web für sie neuartige Medien, Mittel und Aufgaben zu, in erster Linie aus dem Bereich der Wissenschaften und der wissenschaftlichen Fachgesellschaften. Die Herausforderung besteht darin, die neuen elektronischen Informationen und Angebote zu integrieren. Das Stichwort hierzu lautet digitale Bibliothek bzw. virtuelle Fachbibliothek. Auch zu der Diskussion um diese aktuelle Entwicklung will der Artikel einen Beitrag leisten. T3 - ZIB-Report - 00-23 KW - Suchmaschinen KW - Integration Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-5919 ER - TY - GEN A1 - Roitzsch, Rainer T1 - KASKADE Programmer's Manual. N2 - The Programmers Manual contains the documentation of the C-KASKADE implementation. KASKADE is an adaptive finite element code (see SC ). The interfaces of all modules are described. T3 - ZIB-Report - TR-89-05 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4617 ER - TY - GEN A1 - Melenk, Herbert A1 - Neun, Winfried T1 - Implementation of Portable Standard LISP for the SPARC Processor. N2 - The SPARC processor is a RISC (Reduced Instruction Set Computer) microcomputer, built into the SUN4 workstations. Since RISC processors are very well-suited for LISP processing, the implementation of a dialect of LISP (Portable Standard LISP, PSL) boded well for a great speed-up in comparison with other types of microcomputers. A first approach was done at The RAND Corporation in Santa Monica, which was derived from classical processor types like MC68000 or VAX. At the Konrad- Zuse-Zentrum für Informationstechnik Berlin (ZIB) that initial implementation was redesigned in order to adapt PSL to the specific features of the SPARC processor. The present implementation, in some parts, is very close to Cray PSL version also done in ZIB. Some timing informations are given in the appendix. T3 - ZIB-Report - TR-89-06 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4625 ER - TY - GEN A1 - Bornemann, Folkmar A. T1 - Adaptive multilevel discretization in time and space for parabolic partial differential equations. N2 - The present paper developes an adaptive multilevel approach for parabolic PDE's - as a first step, for one linear scalar equation. Full adaptivity of the algorithm is conceptually realized by simultaneous multilevel discretization in both time and space. Thus the approach combines multilevel time discretization, better known as extrapolation methods, and multilevel finite element space discretization such as the hierarchical basis method. The algorithmic approach is theoretically backed by careful application of fundamental results from semigroup theory. These results help to establish the existence of asymptotic expansions (in terms of time-steps) in Hilbert space. Finite element approximation then leads to perturbed expansions, whose perturbations, however, can be pushed below a necessary level by means of an adaptive grid control. The arising space grids are not required to satisfy any quasi- uniformity assumption. Even though the theoretical presentation is independent of space dimension details of the algorithm and numerical examples are given for the 1-D case only. For the 1-D elliptic solver, which is used, an error estimator is established, which works uniformly well for a family of elliptic problems. The numerical results clearly show the significant perspectives opened by the new algorithmic approach. T3 - ZIB-Report - TR-89-07 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4638 ER - TY - GEN A1 - Maierhöfer, Gerhard A1 - Skorobohatyj, Georg T1 - Implementierung des parallelen TRAPEX auf Transputern. N2 - Der folgende Bericht ist eine Ergänzung des ZIB Technical Report TR 88-05. Entsprechend wird hier nicht auf die grundsätzlichen Fragen der Parallelisierbarkeit des sequentiellen TRAPEX eingegangen. Diese sind im TR 88-5 erörtert, die dort beschriebenen Algorithmen (vertikale und horizontale Parallelisierung) werden auch für die Transputerarchitektur verwendet. Meßergebnisse sind im letzten Teil angefügt. T3 - ZIB-Report - TR-89-08 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4649 ER - TY - GEN A1 - Gatermann, Karin T1 - Gruppentheoretische Konstruktion von symmetrischen Kubaturformeln. N2 - $G$-invariant cubature formulas for numerical integration over n-dimensional, $G$- invariant integration regions are computed symbolically. The nodes are the common zeros of some $d$-orthogonal polynomials which build an $H$-basis of an ideal. Approaches for these polynomials depending on parameters are made with the help of the theory of linear representations of a group $G$. This theory is also used for the effective computation of necessary conditions which determines the parameters. Another approach uses invariant theory and gröbner bases. T3 - ZIB-Report - TR-90-01 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4652 ER - TY - GEN A1 - Maierhöfer, Gerhard A1 - Skorobohatyj, Georg T1 - Implementierung von parallelen Versionen der Gleichungslöser EULEX und EULSIM auf Transputern. N2 - Im vorliegenden Bericht wird die Parallelisierung zweier numerischer Algorithmen zur Lösung gewöhnlicher Differentialgleichungssysteme 1.Ordnung (explizite und semi-implizite Euler- Diskretisierung und $h$-Extrapolation) beschrieben. Implementiert wurden die Algorithmen mit OCCAM2 unter TDS (Transputer Development System) mit bis zu 4 Transputern T800. Meßwerte für die erreichten Beschleunigungen werden anhand mehrer Beispiele von Differentialgleichungs-systemen angegeben. {\bf Schlüsselwörter:} Adaptive, parallele Systeme; OCCAM2; Transputer; numerische Gleichungslöser; Euler-Diskretisierung; $h$-Extrapolation. T3 - ZIB-Report - TR-90-02 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4666 ER - TY - GEN T1 - CRAY-Handbuch. Einführung in die Benutzung der CRAY X-MP unter UNICOS 5.1 N2 - Das CRAY-Handbuch des ZIB beschreibt nach einer grundlegenden bersicht detailliert die Handhabung von UNICOS-Dateien, die Verwendung von UNICOS-Kommandos und schließlich die (für Benutzer allein zugelassene) Ausführung von Batchjobs auf der CRAY. Neben der Erreichbarkeit der CRAY über das TCP/IP-Netz werden die Compiler FORTRAN, PASCAL und C beschrieben und schließlich auf die Optimierung der Rechenzeit ebenso wie auf die Fehlersuche eingegangen. Ein umfangreicher Anhang führt bereitgestellte Programmpakete, weiterführende Literatur, Zahlenbereiche und Zeichendarstellung an der CRAY auf. T3 - ZIB-Report - TR-90-03 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4679 ER - TY - GEN A1 - Hege, Hans-Christian T1 - Datenabhängigkeitsanalyse und Programmtransformationen auf CRAY-Rechnern mit dem Fortran-Präprozessor fpp N2 - The FORTRAN preprocessor fpp in the newly introduced Autotasking System of CRAY Research allows automatic vectorization and parallelization on basis of a data dependence analysis. An introduction into data dependence analysis is given, showing how data dependence graphs unveil opportunities for program transformations like vectorization and concurrentization. The report contains a complete description of the preprocessors functionality, its options and directives for increasing the effectiveness of the dependence analyzer and steering the code transformations. Finally, some advice is given for the practical use of fpp on CRAY computers. T3 - ZIB-Report - TR-90-04 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4685 ER - TY - GEN A1 - Grammel, Martin A1 - Maierhöfer, Gerhard A1 - Skorobohatyj, Georg T1 - Trapex in POOL-Implementierung eines numerischen Algorithmus in einer parallelen objektorientierten Sprache. N2 - Die Parallelisierung eines vorhandenen sequentiellen Programmes erfolgt im allgemeinen in der Weise, daß es auf Grund einer Analyse der Datenabhängigkeiten in mehrere parallel ausführbare Teile zerlegt wird, die ihrerseits sequentiell ablaufen und untereinander Daten austauschen. Eine parallele Programmiersprache sollte diese Vorgehensweise unterstützen, indem sie Sprachmittel zur Verfügung stellt, mittels derer sich die Modularisierung und Kommunikation bequem formulieren läßt. Nun läßt sich prinzipiell jede vorhandene sequentielle Programmiersprache um solche Konstrukte erweitern; günstiger in Hinblick auf die Strukturierung eines parallelen Programmes erscheint es aber möglicherweise, eine solche Programmiersprache zu verwenden, die die genannten Konzepte als elementare zur Verfügung stellt. Dies ist offensichtlich bei objektorientierten Programmiersprachen der Fall. Im vorliegenden Bericht wird an Hand eines Beispiels - TRAPEX -, das in POOL-T implementiert wurde, untersucht, inwieweit eine objektorientierte Sprache zur effektiven Programmierung eines numerischen Algorithmus geeignet ist. {\bf Key Words:} parallele objektorientierte Programmiersprache, Message Passing, Abstract Data Typing, Klassenhierarchi, Modul-Import-Mechanismus, Client/Server-Prinzip, Load Balancing, adaptive numerische Algorithmen, Ordnungs- und Schrittweitensteuerung, Romberg-Quadratur. T3 - ZIB-Report - TR-90-05 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4696 ER - TY - GEN A1 - Deuflhard, Peter A1 - Hohmann, Andreas T1 - Einführung in die Numerische Mathematik. N2 - Diese Vorlesung ist eine Einführung in die Numerische Mathematik als einem der drei Bereiche (neben den Naturwissenschaften und der Informatik) des am besten mit dem Begriff Scientific Computing charakterisierten Forschungsgebietes. Aufgabe dieser relativ jungen Wissenschaft ist die Entwicklung von Rechenverfahren für Probleme aus den Naturwissenschaften mit Hilfe mathematischer Methoden. T3 - ZIB-Report - TR-90-06 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4704 ER - TY - GEN A1 - Meyer, Michael T1 - Ab Initio Study of Flavonoids N2 - Flavone and the flavylium ion have been studied at Hartree-Fock, M{\o}ller-Plesset and B3LYP hybrid density functional level to determine the structures and barriers to internal rotation. Both molecules have a high perpendicular barrier about the single bond connecting the phenyl ring with the benzopyrone and benzopyrylium ring, respectively. In contrast to biphenyl both molecules have low coplanar barriers. B3LYP overestimates the perpendicular barrier heights compared to other methods. The dependence of the population and orbital energies on the torsion has been investigated and the structures of both flavonoids have been estimated by means of a reaction field model. T3 - ZIB-Report - SC-99-23 KW - flavonol KW - conformation KW - reaction field KW - structure Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4110 ER - TY - GEN A1 - Grötschel, Martin A1 - Dalitz, Wolfgang T1 - Math-Net Abschlussbericht N2 - Das Math-Net ist ein verteiltes Informationssystem f"ur die Mathematik. Es basiert auf den lokalen Informationsangeboten der Fachbereiche, die im Math-Net integriert, nutzerfreundlich aufbereitet und zug"anglich gemacht werden sollen. Das Math-Net ist durch die freiwillige Mitarbeit weiterer Institutionen in Deutschland zu einem flächendeckenden Dienst ausgebaut worden. Die am Projekt beteiligten Institutionen haben die mathematischen Institutionen in ihrer Region beim Aufbau eines qualitativ hochwertigen lokalen Informationsangebotes unterstützt und die Integration der lokalen Informationsangebote in das Math-Net koordiniert. T3 - ZIB-Report - SC-99-24 KW - Information System KW - Math-Net KW - Math-Net-Links KW - Dublin Core KW - Harvest Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4120 ER - TY - GEN A1 - Schütte, Christof A1 - Huisinga, Wilhelm T1 - On Conformational Dynamics induced by Langevin Processes N2 - The function of many important biomolecules is related to their dynamic properties and their ability to switch between different {\em conformations}, which are understood as {\em almost invariant} or {\em metastable} subsets of the positional state space of the system. Recently, the present authors and their coworkers presented a novel algorithmic scheme for the direct numerical determination of such metastable subsets and the transition probability between them. Although being different in most aspects, this method exploits the same basic idea as {\sc Dellnitz} and {\sc Junge} in their approach to almost invariance in discrete dynamical systems: the almost invariant sets are computed via certain eigenvectors of the Markov operators associated with the dynamical behavior. In the present article we analyze the application of this approach to (high--friction) Langevin models describing the dynamical behavior of molecular systems coupled to a heat bath. We will see that this can be related to theoretical results for (symmetric) semigroups of Markov operators going back to {\sc Davies}. We concentrate on a comparison of our approach in respect to random perturbations of dynamical systems. T3 - ZIB-Report - SC-99-25 KW - Smoluchowski equation KW - Fokker--Planck equation KW - semigroup of Markov operators KW - canonical ensemble KW - small noise KW - first exit time KW - half time perio Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4130 ER - TY - THES A1 - Gatermann, Karin T1 - Computer Algebra Methods for Equivariant Dynamical Systems N2 - An introductory chapter on Groebner bases is given which also includes new results on the detection of Groebner bases for sparse polynomial systems. Algorithms for the computation of invariants and equivariants for finite groups, compact Lie groups and algebraic groups are presented and efficient implementation and time comparision are discussed. This chapter also inlcudes improvements of the computation of Noether normalisation and Stanley decomposition. These results are applied in symmetric bifurcation theory and equivariant dynamics. As preparation of the investigation of the orbit space reduction three methods are compared for solving symmetric polynomial systems exactly. The method of orbit space reduction is improved by using the Cohen-Macaulayness of the invariant ring and nested Noether normalization. Finally this is applied for a case of mode interaction in the Taylor-Couette problem. T3 - ZIB-Report - SC-99-26 KW - Groebner bases KW - algorithmic invariant theory KW - equivariant dynamics KW - orbit space reduction Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4140 ER - TY - GEN A1 - Gatermann, Karin A1 - Huber, Birkett T1 - A family of sparse polynomial systems arising in chemical reaction systems N2 - A class of sparse polynomial systems is investigated which is defined by a weighted directed graph and a weighted bipartite graph. They arise in the model of mass action kinetics for chemical reaction systems. In this application the number of real positive solutions within a certain affine subspace is of particular interest. We show that the simplest cases are equivalent to binomial systems while in general the solution structure is highly determined by the properties of the two graphs. First we recall results by Feinberg and give rigorous proofs. Secondly, we explain how the graphs determine the Newton polytopes of the system of sparse polynomials and thus determine the solution structure. The results on positive solutions from real algebraic geometry are applied to this particular situation. Examples illustrate the theoretical results. T3 - ZIB-Report - SC-99-27 KW - mass action kinetics KW - sparse polynomial systems KW - positive solutions Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4150 ER - TY - GEN A1 - Ilgenfritz, Ernst-Michael A1 - Kerler, Werner A1 - Stüben, Hinnerk T1 - Decorrelation of the topological charge in tempered Hybrid Monte Carlo simulations of QCD N2 - We study the improvement of simulations of QCD with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering. As an indicator for decorrelation we use the topological charge. T3 - ZIB-Report - SC-99-28 KW - QCD KW - parallel tempering KW - topological charge Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4168 ER - TY - GEN A1 - Grötschel, Martin A1 - Krumke, Sven A1 - Rambau, Jörg T1 - Wo bleibt der Aufzug? N2 - Dieser Artikel gibt eine allgemeinverständliche Einführung in die spezielle Problematik kombinatorischer Online-Problem am Beispiel der Fahrstuhlsteuerung. T3 - ZIB-Report - SC-99-29 KW - Aufzugsteuerung KW - Online-Optimierung KW - Echtzeit-Optimierung KW - kompetitive Analyse Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4175 ER - TY - GEN A1 - Steinbach, Marc T1 - Markowitz Revisited: Single-Period and Multi-Period Mean-Variance Models N2 - Mean-variance portfolio analysis provided the first quantitative treatment of the tradeoff between profit and risk. We investigate in detail the interplay between objective and constraints in a number of single-period variants, including semi-variance models. Particular emphasis is laid on avoiding the penalization of overperformance. The results are then used as building blocks in the development and theoretical analysis of multi-period models based on scenario trees. A key property is the possibility to remove surplus money in future decisions, yielding approximate downside risk minimization. T3 - ZIB-Report - SC-99-30 KW - mean-variance analysis KW - downside risk KW - multi-period model Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4183 ER - TY - GEN A1 - Ascheuer, Norbert A1 - Fischetti, Matteo A1 - Grötschel, Martin T1 - Solving the Asymmetric Travelling Salesman Problem with Time Windows by Branch-and-Cut N2 - Many optimization problems have several equivalent mathematical models. It is often not apparent which of these models is most suitable for practical computation, in particular, when a certain application with a specific range of instance sizes is in focus. Our paper addresses the Asymmetric Travelling Salesman Problem with time windows (ATSP-TW) from such a point of view. The real--world application we aim at is the control of a stacker crane in a warehouse. We have implemented codes based on three alternative integer programming formulations of the ATSP-TW and more than ten heuristics. Computational results for real-world instances with up to 233 nodes are reported, showing that a new model presented in a companion paper outperforms the other two models we considered --- at least for our special application --- and that the heuristics provide acceptable solutions. T3 - ZIB-Report - SC-99-31 KW - Asymmetric Travelling Salesman Problem KW - Time Windows KW - Integer Programs KW - Branch&Cut-Algorithm KW - Heuristics KW - Control of Stacker Cranes Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4191 ER - TY - GEN A1 - Langendorf, Jens A1 - Paetsch, Olaf T1 - GRAZIL (Graphical ZIB Language). N2 - GRAZIL ist ein interaktives Programmpaket zur graphischen Darstellung von zwei-dimensionalen Kurvenverläufen. Dem Benutzer stehen zahlreiche Kommandos zum Gestalten des Layouts der Zeichnung zur Verfügung. Die Eingabedaten müssen dem ZUGRIFF- Konzept genügen, wodurch die genaue Struktur der Daten erst zur Laufzeit bekannt sein muß und somit eine hohe Flexibilität und eine große Bandbreite der Einsatzmöglichkeiten erreicht wird. GRAZIL wurde mit der graphischen Grundsoftware BIZEPS2 und GKS entwickelt. Dadurch kann ein breites Rechner- und Ausgabegerätespektrum genutzt werden. T3 - ZIB-Report - TR-87-07 Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4518 ER - TY - GEN A1 - Buhtz, Rainer A1 - Buhtz, Danuta Anna T1 - TDLG 3.1 - Ein interaktives Programm zur Darstellung dreidimensionaler Modelle auf Rastergraphikgeräten. N2 - TDLG 3.1 dient zur Darstellung von dreidimensionalen Objekten, die sich aus offenen Linienzügen, Dreieck- und Viereckelementen zusammensetzen. Dabei können verschiedene Visualisierungstechniken benutzt werden: Drahtmodell, Schattierung mit und ohne Lichtquelle, Hidden Surface Removal. Durch Verwendung von Konvertierungsprogrammen können auch IGES- und VDAFS- Dateien dargestellt werden. T3 - ZIB-Report - TR-88-01 Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4522 ER - TY - GEN A1 - Melenk, Herbert A1 - Neun, Winfried T1 - REDUCE User s Guide for the CRAY 1 / CRAY X-MP Series Running UNICOS. Version 3.3. N2 - This document describes operating procedures for running REDUCE specific to the CRAY 1 and CRAY X-MP computers running the Operating System UNICOS. The document was derived from the corresponding document for Vax/UNIX prepared by A. C. Hearn and L. R. Seward, The Rand Corporation, Santa Monica, (CP85). T3 - ZIB-Report - TR-88-02 Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4539 ER - TY - GEN A1 - Melenk, Herbert A1 - Neun, Winfried T1 - REDUCE Installation Guide for CRAY 1 / X-MP Systems Running UNICOS. Version 3.3. N2 - This guide describes the CRAY/UNICOS REDUCE distribution tape and the procedures for installing, testing and maintaining REDUCE on a CRAY 1 or CRAY X-MP running UNICOS. This document was derived from the corresponding document for Vax/UNIX prepared by A. C. Hearn and L.R. Seward, The Rand Corporation, Santa Monica, publication CP84. T3 - ZIB-Report - TR-88-03 Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4541 ER - TY - GEN A1 - Buhtz, Danuta Anna A1 - Langendorf, Jens A1 - Paetsch, Olaf T1 - GRAZIL - 3D. Ein graphisches Anwendungsprogramm zur Darstellung von Kurven- und Funktionsverläufen im räumlichen Koordinatensystem. N2 - GRAZIL - 3D ist ein interaktives Programmpaket zur graphischen Darstellung von dreidimensionalen Kurvenverläufen. Das Aussehen der räumlichen Ausgabe des Bildes wird durch Angabe des Blickwinkels und der Perspektive festgelegt. T3 - ZIB-Report - TR-88-04 Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4556 ER - TY - GEN A1 - Maierhöfer, Gerhard A1 - Skorobohatyj, Georg T1 - Parallel-TRAPEX (Ein paralleler adaptiver Algorithmus zur numerischen Integration; seine Implementierung für SUPRENUM-artige Architekturen mit SUSI). N2 - This paper describes some ways of transforming a sequential adaptive algorithm for numerical evaluation of an integral (Romberg- Quadrature with polynomial Extrapolation method) to a parallel one, such as have been implementad by the authors. We developed an algorithm which preserves the sequential adaptivity and is capable of running on various architectures, dynamically controlling the number of avtive processors depending on the problem. To study the time behaviour, we used the simulator SUSI(SUprenum SImulatur) which is able to simulate SUPRENUM-like architectures. Results are given in part 3. {\bf Keywords:} Romberg quadrature; numerical integration; parallel adaptive algorithm; SUSI; simulation; SUPRENUM; MIMD-Fortran; computer architecture; granularity; load balacing; master-slave-principle. T3 - ZIB-Report - TR-88-05 Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4560 ER - TY - GEN T1 - CRAY-HANDBUCH. Einführung in die Benutzung der CRAY X-MP unter UNICOS. (veraltet) T3 - ZIB-Report - TR-89-01 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4574 ER - TY - GEN A1 - Deuflhard, Peter T1 - Numerik von Anfangswertmethoden für gewöhnliche Differentialgleichungen. N2 - Das voliegende Skriptum entstand aus einer Vorlesung, die ich im WS 87/88 an der Freien Universität Berlin im Fachbereich Mathematik gehalten habe. Mein ursprüngliches Vorlesungsmanuskript wurde von Herrn F. Bornemann in weiten Teilen überarbeitet, reorganisiert und substantiell ergänzt. Der Inhalt stammt größtenteils aus Originalarbeiten jüngeren Datums. Darüberhinaus finden sich zahlreiche Teile, die aus meiner jahrelangen Beschäftigung mit dem Thema entstanden aber unpubliziert geblieben sind. Das Skriptum erhebt nicht den Anspruch, ein Lehrbuch zu sein. Es war zunächst als Ausarbeitung für meinen studentischen Hörerkreis sowie als internes Arbeitspapier für das ZIB bestimmt. Die Kunde von der bloßen Existenz eines solchen Skriptums hat jedoch zu einer derart regen Nachfrage geführt, daß es hiermit als Technischer Report des ZIB einer breiteren ffentlichkeit zugänglich gemacht werden soll. In der vorliegenden Form richtet es sich in erster Linie an Mathematiker; es soll sich jedoch auch für Naturwissenschaftler und Ingenieure eignen, die sich einen Einblick in den theoretischen und algorithmischen Hintergrund der von ihnen verwendeten wissenschaftlichen Software verschaffen wollen. T3 - ZIB-Report - TR-89-02 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4580 ER - TY - GEN A1 - Walter, Artur T1 - Ein Finite-Element-Verfahren zur numerischen Lösung von Erhaltungsgleichungen. N2 - A new approach for the discretisation of hyperbolic conservation laws via a finite element method is developed and analysed. Appropriate forms of the Eulers equation of gas dynamic are considered to employ the algorithm in a reasonable way for this system of nonlinear equations. Both mathematical and physical stability results are obtained. A main part of the paper is devoted to the convergence proof with energy methods under strong regularity of the solution of a scalar nonlinear conservation law. Some hints on the implementation and numerical results for the calculation of transonic gasflow through a Laval nozzle are given. The necessary amount of numerical work is compared to an established finite difference method and the efficiency of the algorithm is shown. A survey on recent literature about finite element methods for hyperbolic problem is included. T3 - ZIB-Report - TR-89-03 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4597 ER - TY - GEN A1 - Roitzsch, Rainer T1 - KASKADE User's Manual. N2 - The Users Manual contains an introduction to the usage of the C-KASKADE implementation. KASKADE is an adaptive finite element code (see SC ). The manual includes a description of all commands, a simple recipe to define a new problem by changing the KASKADE source and a complete example. T3 - ZIB-Report - TR-89-04 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4605 ER - TY - GEN A1 - Grötschel, Martin A1 - Kuberek, Monika A1 - Lohrum, Stefan A1 - Lügger, Joachim A1 - Rusch, Beate T1 - Der Kooperative Bibliotheksverbund Berlin-Brandenburg N2 - Im Herbst 1999 ging der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) in Routinebetrieb. In technischer Hinsicht setzt der KOBV auf ein neuartiges, zukunftsweisendes Verbundkonzept, in dem die zentrale Datenbank mit dem Verbundkatalog ersetzt wird durch verteilte Datenbanken und lokale Kataloge, die durch das Netz (Internet) miteinander verbunden sind. Die zentrale Recherchefunktion wird ersetzt durch die KOBV-Suchmaschine. Beschrieben werden die Hintergründe, die zu diesem Konzept geführt haben, die Kriterien, die die Architekturentscheidungen der Software bestimmt haben, sowie die einzelnen realisierten Komponenten. T3 - ZIB-Report - SC-99-52 KW - Kooperativer Bibliotheksverbund Berlin-Brandenburg KW - KOBV-Suchmaschine KW - Architektur der Suchmaschine KW - Verteilte Suche KW - Gemeinsamer Index Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4418 ER - TY - GEN A1 - Benger, Werner A1 - Hege, Hans-Christian A1 - Heusler, Stefan T1 - Visions of Numerical Relativity 1999 N2 - We present visualizations of recent supercomputer simulations from numerical relativity, exploiting the progress in visualization techniques and numerical methods also from an artistic point of view. The sequences have been compiled into a video tape, showing colliding black holes, orbiting and merging neutron stars as well as collapsing gravitational waves. In this paper we give some background information and provide a glance at the presented sequences. T3 - ZIB-Report - SC-99-53 KW - General Relativity KW - Data Visualization KW - Numerical Simulations Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4429 ER - TY - GEN A1 - Grötschel, Martin T1 - Verkehrsplanung: Bessere Lösungen mit Mathematik N2 - Anwendungen der Mathematik in der Verkehrs- und Transporttechnologie haben eine große und bedeutende Tradition. Natürlich wurden die ersten Fahrzeuge mit der ingenieurmäßigen Methode von Versuch, Irrtum und Verbesserung entworfen. Aber schon sehr bald kamen mathematische Berechnungen hinzu, mit denen mechanische Eigenschaften von Fahrzeugteilen ermittelt und zum Teil optimiert wurden. Die hierzu erforderliche Mathematik wurde in diesem Jahrhundert zu einem mächtigen Werkzeugkasten ausgebaut. Mit diesem kann man heute z.B. hocheffiziente Motoren mit geringem Schadstoffausstoß entwerfen, aerodynamisch günstige Fahrzeugprofile ermitteln und Flugzeugflügel berechnen, die die gewünschte Last sicher und mit geringem Treibstoffaufwand tragen. Die Mathematik unterstützt die Technologie des Verkehrs beginnend bei globalen Designfragen bis hin zur Spezifizierung von Materialeigenschaften kleinster Bauteile; sie berechnet mit hoher Präzision energieoptimale Bahnen von Raumflugkörpern oder zeitoptimale Trajektorien für Flugzeuge, steuert automatische Roboteranlagen oder innerbetriebliche Transportsysteme. T3 - ZIB-Report - SC-99-54 KW - transportation planning KW - applications of integer programming KW - public transportation Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4439 ER - TY - GEN A1 - Schuster, H. J. T1 - Tätigkeitsbericht-1985. T3 - ZIB-Report - TR-86-01 Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4443 ER - TY - GEN A1 - Busch, Hubert A1 - Pöhle, Uwe A1 - Stech, Wolfgang T1 - CRAY-Handbuch. - Einführung in die Benutzung der CRAY. N2 - Das vorliegende Handbuch wendet sich an alle Benutzer des für den Norddeutschen Vektorrechnerverbund im ZIB installierten Rechners CRAY X-MP/24. Ein großer Teil der Darstellung ist der Optimierung von Programmen gewidmet, die in FORTRAN geschrieben sind. Gerade weil die CRAY einer der schnellsten Rechner der Welt ist, wird jeder Benutzer früher oder später selbst auf dieses Thema stoßen, denn die Maschine ist vornehmlich für Probleme bestimmt, die für die meisten anderen Rechner zu komplex sind. Maschinen der CRAY-Leistungsklasse beziehen einen erheblichen Teil ihrer Geschwindigkeit aus der parallelen Arbeit vieler Komponenten. Programme, die die jeweilige Architektur der Maschine berücksichtigen, können um Größenordnungen schneller (also wirtschaftlicher) sein als Programme, deren Autor beim Schreiben einen sogenannten "klassischen" Rechner vor seinem geistigen Auge hatte. Daher wird auch der technische Aufbau der CRAY X-MP im Handbuch erläutert. Weitere Teile des Handbuches beschäftigen sich mit den Vorrechnern und dem Rechnernetz. T3 - ZIB-Report - TR-87-01 Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4459 ER - TY - GEN A1 - Melenk, Herbert A1 - Neun, Winfried T1 - Portable Standard LISP Implementation for CRAY X+MP Computers. Release of PSL 3.4 for COS. N2 - Portable Standard LISP (PSL) is a portable implementation of the programming language LISP constructed at the University of Utah. The version 3.4 of PSL was implemented for CRAY X-MP computers by Konrad Zuse-Zentrum Berlin; this implementation is based to an important part on the earlier implementation of PSL 3.2 at Salt Lake City, Los Alamos and Mendota Heights. T3 - ZIB-Report - TR-87-02 Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4465 ER - TY - GEN A1 - Melenk, Herbert A1 - Neun, Winfried T1 - Portable Common LISP Subset Implementation for CRAY X+MP Computers. N2 - This document describes the installation procedure and maintenance for the Portable Common LISP Subset (PCLS) developed at the University of Utah. T3 - ZIB-Report - TR-87-03 Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4479 ER - TY - GEN A1 - Melenk, Herbert A1 - Neun, Winfried T1 - REDUCE Installation Guide for CRAY 1 / X-MP Systems Running COS. Version 3.3. N2 - This guide describes the CRAY/COS REDUCE distribution tape and the procedures for installing, testing and maintaining REDUCE on a CRAY 1 or CRAY X-MP running COS. This document was derived from the corresponding document for Vax/Unix prepared by A. C. Hearn and L. R. Seward, The Rand Corporation, Santa Monica, publication CP84. T3 - ZIB-Report - TR-87-04 Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4486 ER - TY - GEN A1 - Melenk, Herbert A1 - Neun, Winfried T1 - REDUCE Users Guide for the CRAY 1 / X-MP Series Running COS. Version 3.3. N2 - This document describes operating procedures for running REDUCE specific to the CRAY 1 and CRAY X-MP computers running the CRAY Operating System (COS). The document was derived from the corresponding document for Vax/UNIX prepared by A.C. Hearn and L.R. Seward, The Rand Corporation, Santa Monica, (CP85). T3 - ZIB-Report - TR-87-05 Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4498 ER - TY - GEN A1 - Buhtz, Rainer A1 - Langendorf, Jens A1 - Paetsch, Olaf A1 - Buhtz, Danuta Anna T1 - ZUGRIFF - Eine vereinheitlichte Datenspezifikation für graphische Darstellungen und ihre graphische Aufbereitung. N2 - ZUGRIFF ist eine Dateischnittstelle für Graphikausgabe speziell numerischer Anwenderprogramme. Dieser Report beschreibt den Leistungsumfang der Spezifikation sowie die interaktive graphische Verarbeitung von ZUGRIFF- Dateien. T3 - ZIB-Report - TR-87-06 Y1 - 1987 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4506 ER - TY - GEN A1 - Seewald, Frank A1 - Pollei, Anja A1 - Kraume, Matthias A1 - Mittelbach, Walter A1 - Lang., Jens T1 - Numerical Calculation of the Heat Transfer in an Adsorption Energy Storage with KARDOS N2 - A new seasonal energy storage for thermal solar systems has been developed on the basis of an adsorption-desorption process. Design and optimization of this storage will be supported by numerical simulations of heat and mass transfer with KARDOS. This paper focuses on the unsteady heat transfer during the major operating step of energetic discharge of the storage, which is characterized by conductive heat transfer in the fixed bed and a strong heat source caused by the adsorption enthalpy. Results are interpreted concerning the influence of variations in the parameter set. The method of implementation of the differential equation will be shown as well as the post-processing and gridwriting programs. T3 - ZIB-Report - SC-99-04 Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3927 ER - TY - GEN A1 - Lohrum, Stefan A1 - Schneider, Wolfram A1 - Willenborg, Josef T1 - De-duplication in KOBV N2 - In KOBV we offer the user an efficient tool for searching regional and worldwide accessible library catalogues (KOBV search engine). Search is performed by a distributed Z39.50 retrieval and an index based quicksearch. Due to the number of catalogues, result sets may contain a significant amount of duplicate records. Therefore we integrate a de-duplication procedure into KOBV search engine. It is part of the distributed search and the KOBV quicksearch as well. Main goals are the presentation of uniform retrieval results, the preservation of retrieval quality and cutting off redundant information. At least we keep an eye on efficiency. De-duplication is fully parametrizable, so that settings can be changed easily on line. T3 - ZIB-Report - SC-99-05 KW - de-duplication method KW - distributed library system KW - clustering Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3931 ER - TY - GEN A1 - Hauptmeier, Dietrich A1 - Krumke, Sven A1 - Rambau, Jörg A1 - Wirth., Hans-Christoph T1 - Euler is Standing in Line N2 - In this paper we study algorithms for ``Dial-a-Ride'' transportation problems. In the basic version of the problem we are given transportation jobs between the vertices of a graph and the goal is to find a shortest transportation that serves all the jobs. This problem is known to be NP-hard even on trees. We consider the extension when precedence relations between the jobs with the same source are given. Our results include a polynomial time algorithm on paths and an approximation algorithm on general graphs with a performance of~$9/4$. For trees we improve the performance to~$5/3$. T3 - ZIB-Report - SC-99-06 KW - NP-completeness KW - polynomial-time approximation algorithms KW - stacker-crane problem KW - vehicle routing KW - elevator system KW - Eulerian Cycle Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3947 ER - TY - GEN A1 - Braess, Dietrich A1 - Deuflhard, Peter A1 - Lipnikov, Konstantin T1 - A Subspace Cascadic Multigrid Method for Mortar Elements N2 - A cascadic multigrid (CMG) method for elliptic problems with strong material jumps is proposed and analyzed. Non--matching grids at interfaces between subdomains are allowed and treated by mortar elements. The arising saddle point problems are solved by a subspace confined conjugate gradient method as smoother for the CMG. Details of algorithmic realization including adaptivity are elaborated. Numerical results illustrate the efficiency of this CMG algorithm. T3 - ZIB-Report - SC-99-07 KW - Finite Elements KW - Rayleigh-Ritz and Galerkin Methods KW - Multigrid Methods KW - Domain Decomposition Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3954 ER - TY - GEN A1 - Hauptmeier, Dietrich A1 - Krumke, Sven A1 - Rambau, Jörg T1 - The Online Dial-a-Ride Problem under Reasonable Load N2 - In this paper, we analyze algorithms for the online dial-a-ride problem with request sets that fulfill a certain worst-case restriction: roughly speaking, a set of requests for the online dial-a-ride problem is reasonable if the requests that come up in a sufficiently large time period can be served in a time period of at most the same length. This new notion is a stability criterion implying that the system is not overloaded. The new concept is used to analyze the online dial-a-ride problem for the minimization of the maximal resp.\ average flow time. Under reasonable load it is possible to distinguish the performance of two particular algorithms for this problem, which seems to be impossible by means of classical competitive analysis. T3 - ZIB-Report - SC-99-08 KW - online optimization KW - competitive analysis KW - elevator Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3961 ER - TY - GEN A1 - Grötschel, Martin A1 - Hauptmeier, Dietrich A1 - Krumke, Sven A1 - Rambau, Jörg T1 - Simulation Studies for the Online-Dial-a-Ride Problem N2 - In a large distribution center of Herlitz AG, Berlin, we invesigated the elevator subsystem of the fully automated pallet transportation system. Each elevator may carry one pallet and has to serve eight levels. The goal is to minimize the average resp.\ the maximum flow time. The variants of this elevator control problem have been subject of recent theoretical research and are known as online-dial-a-ride problems. In this paper we investigate several online algorithms for several versions of online-dial-a-ride problems by means of a simulation program, developed on the basis of the simulation library AMSEL. We draw statistics from samples of randomly generated data providing for different load situations. Moreover, we provide preliminary studies with real production data for a system of five elevators connected by a conveyor circuit, as can be found at the Herlitz plant. We show which algorithms are best under certain load situations and which lead to break downs under particular circumstances. T3 - ZIB-Report - SC-99-09 KW - online optimization KW - competitive analysis KW - elevator KW - simulation studies Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3976 ER - TY - GEN A1 - Schütte, Christof T1 - Partial Wigner Transforms and the Quantum--Classical Liouville Equation N2 - In molecular dynamics applications there is a growing interest in mixed quantum-classical models. The {\em quantum-classical Liouville equation} (QCL) describes most atoms of the molecular system under consideration by means of classical phase space density but an important, small portion of the system by means of quantum mechanics. The QCL is derived from the full quantum dynamical (QD) description by applying the Wigner transform to the classical part'' of the system only. We discuss the conditions under which the QCL model approximates the full QD evolution of the system. First, analysis of the asymptotic properties of the Wigner transform shows that solving the QCL yields a first order approximation of full quantum dynamics. Second, we discuss the adiabatic limit of the QCL. This discussion shows that the QCL solutions may be interpretated as classical phase space densities, at least near the adiabatic limit. Third, it is demonstrated that the QCL yields good approximations of {\em non-adiabatic quantum effects,} especially near so-called {\em avoided crossings} where most quantum-classical models fail. T3 - ZIB-Report - SC-99-10 KW - QCMD KW - quantum-classical Liouville equation KW - surface hopping KW - Wigner transform KW - asymptotic expansion KW - nonadiabatic effects Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3983 ER - TY - GEN A1 - Schmidt, Burkhard A1 - Zdanska, Petra T1 - Solution of the Time-Dependent Schroedinger Equation for Highly Symmetric Potentials N2 - The method of symmetry adapted wavepackets (SAWP) to solve the time-dependent Schrödinger equation for a highly symmetric potential energy surface is introduced. The angular dependence of a quantum-mechanical wavepackets is expanded in spherical harmonics where the number of close-coupled equations for the corresponding radial functions can be efficiently reduced by symmetry adaption of the rotational basis using the SWAP approach. Various techniques to generate symmetry adapted spherical harmonics (SASHs) for the point groups of highest symmetry (octahedral, icosahedral) are discussed. The standard projection operator technique involves the use of Wigner rotation matrices. Two methods to circumvent numerical instabilities occuring for large azimuthal quantum numbers are suggested. The first is based on a numerical scheme which employs Gaussian integrations yielding exact and stable results. The second is a recursive algorithm to generate higher order SASHs accurately and efficiently from lower order ones. The paper gives a complete set of ``seed functions'' generated by projection techniques which can be used obtain SASHs for all irreducible representations of the octahedral and icosahedral point groups recursively. T3 - ZIB-Report - SC-99-11 KW - Schroedinger Equation KW - quantum mechanics KW - symmetry KW - group theory Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3996 ER - TY - GEN A1 - Backhaus, Peter A1 - Schmidt, Burkhard A1 - Dantus, Marcos T1 - Control of photoassociation yield: A quantum-dynamical study of the mercury system to explore the role of pulse duration from nanoseconds to femtoseconds N2 - The photoassociation process shows strong dependence on the temporal duration of the electromagnetic field pulses and their frequencies. This dependence is investigated using quantum mechanical simulations that include all ranges of impact parameters and contributions from bound-to-bound transitions. The photoassociation yield of mercury atoms to produce excimer dimers is enhanced for short (ps) and for ultrashort (fs) pulse durations. Ultrashort laser pulses effectively overlap the entire range of free-to-bound transition, therefore achieving a maximum probability. Short pulses show a maximum in the photoassociation yield when their carrier frequency overlaps a particular free-to-bound spectroscopic resonance. Implications of these calculations on efforts to control bimolecular reactions are discussed. T3 - ZIB-Report - SC-99-12 KW - photoassociation KW - laser pulse control Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4001 ER - TY - GEN A1 - Zöckler, Malte A1 - Stalling, Detlev A1 - Hege, Hans-Christian T1 - Fast and Intuitive Generation of Geometric Shape Transitions N2 - We describe a novel method for continuously transforming two triangulated models of arbitrary topology into each other. Equal global topology for both objects is assumed, extensions for genus changes during metamorphosis are provided. The proposed method addresses the major challenge in 3D metamorphosis, namely specifying the morphing process intuitively, with minimal user interaction and sufficient detail. Corresponding regions and point features are interactively identified. These regions are parametrized automatically and consistently, providing a basis for smooth interpolation. Utilizing suitable 3D interaction techniques a simple and intuitive control over the whole morphing process is offered. T3 - ZIB-Report - SC-99-33 KW - morphing KW - surface parametrization KW - shape transition Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4219 ER - TY - GEN A1 - Deuflhard, Peter T1 - Differential Equations in Technology and Medicine. Computational Concepts, Adaptive Algorithms, and Virtual Labs N2 - This series of lectures has been given to a class of mathematics postdocs at a European summer school on Computational Mathematics Driven by Industrial Applications in Martina Franca, Italy (organized by CIME). It deals with a variety of challenging real life problems selected from clinical cancer therapy, communication technology, polymer production, and pharmaceutical drug design. All of these problems from rather diverse application areas share two common features: (a) they have been modelled by various differential equations -- elliptic, parabolic, or Schrödinger--type partial differential equations, countable ordinary diffential equations, or Hamiltonian systems, (b) their numerical solution has turned out to be real challenge to computational mathematics. T3 - ZIB-Report - SC-99-34 KW - differential equations: KW - ordinary KW - partial KW - countable KW - hamiltonian KW - finite element methods: KW - adaptive KW - multilevel KW - grid generation KW - medical t Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4223 ER - TY - GEN A1 - Linke, Matthias A1 - Krebs, Carsten A1 - Schünemann, Marion T1 - Metacomputing zwischen Berlin und Rostock N2 - Das Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB) und das Rechenzentrum der Universität Rostock, beide Einrichtungen betreiben massiv-parallele Rechner vom Typ CRAY T3E, haben sich an Hand einer Anwendung aus dem Bereich der Botanik mit den Möglichkeiten der Verteilung auf zwei Parallelrechner, gekoppelt nur über das Breitband-Wissenschaftsnetz des Deutschen Forschungsnetzes, vertraut gemacht. Das Projekt besteht aus zwei Teilen. Im ersten Teil wird ausführlich das zwischen den Rechnern liegende Netz und die Ergebnisse einer Performanceanalyse dieses Netzes dokumentiert. Der zweite Teil beschreibt die Anwendung "Simulation des Wachstums von Pflanzen"' sowie die Ergebnisse der Verteilung dieser Anwendung auf beide Rechner. \begin{center} \bf{Abstract} \end{center} The "'Konrad-Zuse-Zentrum für Informationstechnik Berlin"' (ZIB) and the Computing Centre of the University of Rostock operate high-performance computers of type CRAY T3E. In this project an application from the area of the botany is distributed on two parallel computers, only coupled through the Broadband Science Network of the German Research Network (DFN). This project consists of two parts. In the first part the network which is situated between the computers and the results of a performance analysis is documented in detail. The second part describes the application "'Simulation of the growth of plants"' as well as the results of the distribution of this application to both computers. T3 - ZIB-Report - SC-99-35 KW - Metacomputing KW - Performanceanalyse KW - verteilte Anwendung KW - Latenzzeiten KW - Bandbreite Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4239 ER - TY - GEN A1 - Schütte, Christof A1 - Huisinga, Wilhelm A1 - Deuflhard, Peter T1 - Transfer Operator Approach to Conformational Dynamics in Biomolecular Systems N2 - The article surveys the development of novel mathematical concepts and algorithmic approaches based thereon in view of their possible applicability to biomolecular design. Both a first deterministic approach, based on the Frobenius-Perron operator corresponding to the flow of the Hamiltonian dynamics, and later stochastic approaches, based on a spatial Markov operator or on Langevin dynamics, can be subsumed under the unified mathematical roof of the transfer operator approach to effective dynamics of molecular systems. The key idea of constructing specific transfer operators especially taylored for the purpose of conformational dynamics appears as the red line throughout the paper. Different steps of the algorithm are exemplified by a trinucleotide molecular system as a small representative of possible RNA drug molecules. T3 - ZIB-Report - SC-99-36 KW - Transfer operator KW - Markov process KW - Markov chain KW - molecular dynamics KW - biomolecular conformations KW - canonical ensemble KW - transition prohability KW - Ha Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4247 ER - TY - GEN A1 - Helmberg, Christoph A1 - Kiwiel, K.C. T1 - A Spectral Bundle Method with Bounds N2 - Semidefinite relaxations of quadratic 0-1 programming or graph partitioning problems are well known to be of high quality. However, solving them by primal-dual interior point methods can take much time even for problems of moderate size. The recent spectral bundle method of Helmberg and Rendl can solve quite efficiently large structured equality-constrained semidefinite programs if the trace of the primal matrix variable is fixed, as happens in many applications. We extend the method so that it can handle inequality constraints without seriously increasing computation time. Encouraging preliminary computational results are reported. T3 - ZIB-Report - SC-99-37 KW - Eigenvalue optimization KW - convex optimization Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4256 ER - TY - GEN A1 - Galliat, Tobias A1 - Huisinga, Wilhelm A1 - Deuflhard, Peter T1 - Self-Organizing Maps Combined with Eigenmode Analysis for Automated Cluster Identification N2 - One of the important tasks in Data Mining is automated cluster analysis. Self-Organizing Maps (SOMs) introduced by {\sc Kohonen} are, in principle, a powerful tool for this task. Up to now, however, its cluster identification part is still open to personal bias. The present paper suggests a new approach towards automated cluster identification based on a combination of SOMs with an eigenmode analysis that has recently been developed by {\sc Deuflhard et al.} in the context of molecular conformational dynamics. Details of the algorithm are worked out. Numerical examples from Data Mining and Molecular Dynamics are included. T3 - ZIB-Report - SC-99-38 KW - Self-Organizing Maps KW - cluster analysis Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4279 ER - TY - GEN A1 - Schmidt-Ehrenberg, Johannes A1 - Hege, Hans-Christian T1 - Visualizing Quantum Mechanical Phenomena N2 - In this paper we discuss several ways to visualize stationary and non-stationary quantum mechanical systems. We demonstrate an approach for the quantitative interpretation of probability density isovalues which yields a reasonable correlation between isosurfaces for different timesteps. As an intuitive quantity for visualizing the momentum of a quantum system we propose the probability flow density which can be treated by vector field visualization techniques. Finally, we discuss the visualization of non-stationary systems by a sequence of single timestep images. T3 - ZIB-Report - SC-99-39 KW - quantum dynamics KW - isosurfaces KW - probability flow KW - animation Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4287 ER - TY - GEN A1 - Beck, Rudolf T1 - Algebraic Multigrid by Component Splitting for Edge Elements on Simplicial Triangulations N2 - Our focus is on Maxwell's equations in the low frequency range; two specific applications we aim at are time-stepping schemes for eddy current computations and the stationary double-curl equation for time-harmonic fields. We assume that the computational domain is discretized by triangles or tetrahedrons; for the finite element approximation we choose N\'{e}d\'{e}lec's $H(curl)$-conforming edge elements of the lowest order. For the solution of the arising linear equation systems we devise an algebraic multigrid preconditioner based on a spatial component splitting of the field. Mesh coarsening takes place in an auxiliary subspace, which is constructed with the aid of a nodal vector basis. Within this subspace coarse grids are created by exploiting the matrix graphs. Additionally, we have to cope with the kernel of the $curl$-operator, which comprises a considerable part of the spectral modes on the grid. Fortunately, the kernel modes are accessible via a discrete Helmholtz decomposition of the fields; they are smoothed by additional algebraic multigrid cycles. Numerical experiments are included in order to assess the efficacy of the proposed algorithms. T3 - ZIB-Report - SC-99-40 KW - Algebraic multigrid KW - mesh coarsening KW - edge elements KW - N\'{e}d\'{e}lec spaces KW - Maxwell's equations Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4290 ER - TY - GEN A1 - Deuflhard, Peter T1 - Zuses Werk weiterdenken. (Vortrag) T3 - ZIB-Report - TR-90-07 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4717 ER - TY - GEN A1 - Wulkow, Michael T1 - Numerical Treatment of Countable Systems of Ordinary Differential Equations. N2 - Countable systems of ordinary differential equations appear frequently in chemistry, physics, biology and medicine. They can be considered as ordinary differential equations in sequence spaces. In this work, a full adaptive algorithm for the computational treatment of such systems is developed. The method combines time discretization with extrapolation in Hilbert spaces with a discrete Galerkin approach as discretization of the stationary subproblems. The Galerkin method is based on orthogonal functions of a discrete variable , which are generated by certain weight functions. A theory of countable systems in the associated weighted sequence spaces is developed as well as a theory of the Galerkin method. The Galerkin equations can be assembled either by use of analytical properties of the orthogonal functions or numerically by a multilevel summation algorithm. The resulting algorithm CODEX is applied to many examples of technological interest, in particular from polymer chemistry. T3 - ZIB-Report - TR-90-08 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4728 ER - TY - GEN A1 - Roitzsch, Rainer A1 - Kornhuber, Ralf T1 - BOXES - a Program to Generate Triangulations from a Rectangular Domain Description. N2 - BOXES computes a triangulation from a 2D domain description which consists of an arbitrary set of rectangles. Each rectangle may have attributes to control the triangulating process, define subdomain classes, or specify boundary conditions. The output of the program can be used as a coarse grid for KASKADE or one of its variants. Additional features are extensive checking of the user input, graphical display, and simple editing. T3 - ZIB-Report - TR-90-09 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4738 ER - TY - GEN A1 - Nowak, Ulrich A1 - Weimann, Lutz T1 - GIANT - A Software Package for the Numerical Solution of Very Large Systems of Highly Nonlinear Equations. N2 - This report presents the final realization and implementation of a global inexact Newton method proposed by Deuflhard. In order to create a complete piece of software, a recently developed iterative solver (program GBIT) due to Deuflhard, Freund, Walter is adapted and serves as the standard iterative linear solver. Alternative linear iterative solvers may be adapted as well, e.g. the widely distributed code GMRES. The new software package GIANT (Global Inexact Affine Invariant Newton Techniques) allows an efficient and robust numerical solution of very large scale highly nonlinear systems. Due to the user friendly interface and its modular design, the software package is open for an easy adaptation to specific problems. Numerical experiments for some selected problems illustrate performance and usage of the package. T3 - ZIB-Report - TR-90-11 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4746 ER - TY - GEN A1 - Giloi, Wolfgang K. T1 - Konrad Zuses Plankalkül als Vorläufer moderner Programmier-modelle. (Vortrag) T3 - ZIB-Report - TR-90-13 Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4759 ER - TY - GEN A1 - Bornemann, Folkmar A. A1 - Erdmann, Bodo A1 - Roitzsch, Rainer T1 - KASKADE - Numerical Experiments. N2 - The C-implementation of KASKADE, an adaptive solver for linear elliptic differential equations in 2D, is object of a set of numerical experiments to analyze the use of resources (time and memory) with respect to numerical accuracy. We study the dependency of the reliability, robustness, and efficiency of the program from the parameters controlling the algorithm. T3 - ZIB-Report - TR-91-01 Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4762 ER - TY - GEN A1 - Lügger, Joachim A1 - Dalitz, Wolfgang T1 - Verteilung mathematischer Software mittels elektronischer Netze: Die elektronische Softwarebibliothek eLib. N2 - Mit zunehmender Dezentralisierung im Bereich des Wissenschaftlichen Rechnens steigt auch der Bedarf an Softwarequellen qualitativ hochwertiger mathematischer Algorithmen. Für den Software- und Informationsaustausch wird die Einrichtung öffentlicher, elektronischer Softwarebibliotheken vorgeschlagen. Am Beispiel der eLib des ZIB werden die notwendigen technischen Konzepte, die u.a. auch in den heutigen Gegebenheiten der technischen Kommunikation begründet sind, diskutiert. Die eLib ist fenster- und menüorientiert aufgebaut und folglich im Dialog sehr einfach zu benutzen. Sie kann aber auch mit ihrer Kommandosprache allein auf dem Wege über elektronische Post abgefragt werden. Über die eLib sind, nach dem Verbund mit den Netzbibliotheken NetLib und Reduce-NetLib jetzt etwa 6000 mathematische Programme und allgemeine Dokumente verfügbar. Das Dienstleistungsangebot der eLib setzt Beiträge aus einer aktiven Benutzergemeinschaft voraus. Es besteht die Hoffnung, daß durch den öffentlichen Softwareaustausch sich Entwickler und Anwender wechselseitig in ihrer Arbeit befruchten. T3 - ZIB-Report - TR-91-02 Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4774 ER - TY - GEN A1 - Noelle, Sebastian W. C. T1 - On the Limits of Operator Splitting: Numerical Experiments for the Complex Burgers Equation. N2 - A high resolution Godunov-type method is developed and applied to a two-dimensional version of the Burgers equation. On one-dimensional testproblems the scheme is second order accurate for smooth flow and resolves discontinuities sharply. On two-dimensional problems, however, large numerical oscillations are introduced when discontinuities traveling obliquely to the grid directions are present. These oscillations are caused by a Strang- type operator splitting, and cannot be eliminated using flux limiters or small timesteps. {\bf Keywords:} High resolution methods, Godunovs method, operator splitting, complex Burgers equation. {\bf AMS:} 35: A40, L45, L60, L65, L, 67. 65: M05, M10. T3 - ZIB-Report - TR-91-03 Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4789 ER - TY - GEN A1 - Lang, Jens T1 - An Adaptive Finite Element Method for Convection-Diffusion Problems by Interpolation Techniques. N2 - For adaptive solution of convection- difussion problems with the streamline-diffusion finite element method, an error estimator based on interpolation techniques is developed. It can be shown that for correctness of this error estimator a restriction of the maximum angle is to be sufficient. Compared to usual methods, the adaptive process leads to more accurate solutions at much less computational cost. Numerical tests are enclosed. {\bf Keywords: } Adaptive finite elements, convection- diffusion equation, internal and boundary layers, streamline-diffusion. {\bf Subject Classifications:} AMS(MOS): 65N15, 65N30 T3 - ZIB-Report - TR-91-04 Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4795 ER - TY - GEN A1 - Gottschewski, Jürgen T1 - Supercomputing During the German Reunification. N2 - The success of the German Reunification requires a unique migration from the traditional Eastern Block system to a modern free society. The successful migration must include a shift from a low state of the art in technology to the high level of science and technology present in the Western Community. The role of supercomputing in this transition will include leading the process of organizational change in research and development. The paper contains a short overview on the current state of this evolution, on the currently used political and administrative tools to keep this evolution on track, and on the influence on the Konrad-Zuse-Zentrum, which is, as a Berlin institution, in the geographical and cultural center of this transformation. T3 - ZIB-Report - TR-91-05 Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4803 ER - TY - GEN A1 - Galliat, Tobias T1 - Clustering Data of Different Information Levels N2 - For using Data Mining, especially cluster analysis, one needs measures to determine the similarity or distance between data objects. In many application fields the data objects can have different information levels. In this case the widely used euclidean distance is an inappropriate measure. The present paper describes a concept how to use data of different information levels in cluster analysis and suggests an appropriate similarity measure. An example from practice is included, that shows the usefulness of the concept and the measure in combination with {\sc Kohonens} Self-Organizing Map algorithm, a well-known and powerful tool for cluster analysis. T3 - ZIB-Report - SC-99-42 KW - cluster analysis KW - Data Mining KW - data preprocessing KW - information theory KW - missing values KW - Self-Organizing Maps KW - similarity measures Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4319 ER - TY - GEN A1 - Benger, Werner A1 - Hege, Hans-Christian A1 - Merzky, Andre A1 - Radke, Thomas A1 - Seidel, Edward T1 - Efficient Distributed File I/O for Visualization in Grid Environments N2 - Large scale simulations running in metacomputing environments face the problem of efficient file I/O. For efficiency it is desirable to write data locally, distributed across the computing environment, and then to minimize data transfer, i.e.\ reduce remote file access. Both aspects require I/O approaches which differ from existing paradigms. For the data output of distributed simulations, one wants to use fast local parallel I/O for all participating nodes, producing a single distributed logical file, while keeping changes to the simulation code as small as possible. For reading the data file as in postprocessing and file based visualization, one wants to have efficient partial access to remote and distributed files, using a global naming scheme and efficient data caching, and again keeping the changes to the postprocessing code small. However, all available software solutions require the entire data to be staged locally (involving possible data recombination and conversion), or suffer from the performance problems of remote or distributed file systems. In this paper we show how to interface the HDF5 I/O library via its flexible Virtual File Driver layer to the Globus Data Grid. We show, that combining these two toolkits in a suitable way provides us with a new I/O framework, which allows efficient, secure, distributed and parallel file I/O in a metacomputing environment. T3 - ZIB-Report - SC-99-43 KW - Grid KW - Data Grid KW - Globus KW - HDF5 KW - Cactus KW - CCTK KW - Amira KW - VFD KW - Storage Systems Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4326 ER - TY - GEN A1 - Marchand, Hugues A1 - Martin, Alexander A1 - Weismantel, Robert A1 - Wolsey, Laurence T1 - Cutting Planes in Integer and Mixed Integer Programming N2 - This survey presents cutting planes that are useful or potentially useful in solving mixed integer programs. Valid inequalities for i) general integer programs, ii) problems with local structure such as knapsack constraints, and iii) problems with 0-1 coefficient matrices, such as set packing, are examined in turn. Finally the use of valid inequalities for classes of problems with structure, such as network design, is explored. T3 - ZIB-Report - SC-99-44 KW - Mixed Integer Programming KW - Cutting Planes Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4339 ER - TY - GEN A1 - Friese, Tilman A1 - Schmidt, Frank A1 - Yevick, David T1 - Transparent Boundary Conditions for a Wide-Angle Approximation of the One-Way Helmholtz Equation N2 - We present nonlocal discrete transparent boundary conditions for a fourth-order wide-angle approximation of the two-dimensional Helmholtz equation. The boundary conditions are exact in the sense that they supply the same discrete solution on a bounded interior domain as would be obtained by considering the problem on the entire unbounded domain with zero boundary conditions at infinity. The proposed algorithm results in an unconditionally stable propagation method. Numerical examples from optics illustrate the efficiency of our approach. T3 - ZIB-Report - SC-99-45 KW - Helmholtz equation KW - Wide-angle approximation KW - Transparent boundary conditions KW - Finite-element method Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4345 ER - TY - GEN A1 - Schmidt, Frank A1 - Friese, Tilmann A1 - Yevick, David T1 - Transparent Boundary Conditions for Split-Step Pade Approximations of the One-Way Helmholtz Equation N2 - In this paper, we generalize the nonlocal discrete transparent boundary condition introduced by Schmidt and Deuflhard {[}Comp. Math. Appl. 29 (1995) 53-76{]} and Schmidt and Yevick {[}J. Comput. Phys. 134 (1997) 96-107{]} to propagation methods based on arbitrary Pad\'e approximations to the two-dimensional one-way Helmholtz equation. Our approach leads to a recursive formula for the coefficients appearing in the nonlocal condition which then yields an unconditionally stable propagation method. T3 - ZIB-Report - SC-99-46 KW - Helmholtz equation KW - Wide-angle approximation KW - Pad/'e split step approximation KW - Transparent boundary conditions KW - Finite-element method Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4353 ER - TY - GEN A1 - Stüben, Hinnerk T1 - Decorrelation of the Topological Charge in Tempered Simulations of Full QCD N2 - The improvement of simulations of QCD with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering is studied. As an indicator for decorrelation the topological charge is used. T3 - ZIB-Report - SC-99-47 KW - QCD KW - parallel tempering KW - topological charge Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4369 ER - TY - GEN A1 - Helmberg, Christoph T1 - The m-Cost ATSP N2 - Although the m-ATSP (or multi traveling salesman problem) is well known for its importance in scheduling and vehicle routing, it has, to the best of our knowledge, never been studied polyhedraly, i.e., it has always been transformed to the standard ATSP. This transformation is valid only if the cost of an arc from node $i$ to node $j$ is the same for all machines. In many practical applications this is not the case, machines produce with different speeds and require different (usually sequence dependent) setup times. We present first results of a polyhedral analysis of the m-ATSP in full generality. For this we exploit the tight relation between the subproblem for one machine and the prize collecting traveling salesman problem. We show that, for $m\ge 3$ machines, all facets of the one machine subproblem also define facets of the m-ATSP polytope. In particular the inequalities corresponding to the subtour elimination constraints in the one machine subproblems are facet defining for m-ATSP for $m\ge 2$ and can be separated in polynomial time. Furthermore, they imply the subtour elimination constraints for the ATSP-problem obtained via the standard transformation for identical machines. In addition, we identify a new class of facet defining inequalities of the one machine subproblem, that are also facet defining for m-ATSP for $m\ge 2$. To illustrate the efficacy of the approach we present numerical results for a scheduling problem with non-identical machines, arising in the production of gift wrap at Herlitz PBS AG. T3 - ZIB-Report - SC-99-48 KW - ATSP KW - polyhedral relaxations KW - scheduling KW - nonidentical machines Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4374 ER - TY - GEN A1 - Helmberg, Christoph T1 - Semidefinite Programming N2 - Due to its many applications in control theory, robust optimization, combinatorial optimization and eigenvalue optimization, semidefinite programming had been in wide spread use even before the development of efficient algorithms brought it into the realm of tractability. Today it is one of the basic modeling and optimization tools along with linear and quadratic programming. Our survey is an introduction to semidefinite programming, its duality and complexity theory, its applications and algorithms. T3 - ZIB-Report - SC-99-49 KW - semidefinite programming Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4382 ER - TY - GEN A1 - Kuberek, Monika T1 - Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) - Ein innovatives Verbundkonzept für die Region N2 - Auf dem 89. Deutschen Bibliothekartag, der vom 25. bis 29. Mai 1999 in Freiburg (Breisgau) stattgefunden hat, wurde der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) zum ersten Mal der großen bibliothekarischen Öffentlichkeit vorgestellt. Am KOBV-Stand, der im Rahmen des gemeinsamen Standes der Arbeitsgemeinschaft der Verbundsysteme organisiert wurde, führte die KOBV-Projektgruppe Funktionalitäten der KOBV-Suchmaschine vor. In der Vortragsreihe zum Themenkreis XI "Neue Entwicklungen in den Verbund- und Lokalsystemen", die unter Mitwirkung der Arbeitsgemeinschaft der Verbundsysteme veranstaltet wurde, war der KOBV mit einem eigenen Vortrag vertreten: "Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) - Ein innovatives Verbundkonzept für die Region". In dem Vortrag hat die Verfasserin einen umfassenden Überblick über das KOBV-Projekt und den bisherigen Projektverlauf gegeben, die Projektziele und den politischen Rahmen erörtert sowie die KOBV-Suchmaschine, das technische Kernstück des neuen Verbundes, vorgestellt. Der hier vorliegende Text ist die schriftlich ausgearbeitete Fassung dieses Vortrages. T3 - ZIB-Report - SC-99-50 KW - Bibliotheksverbund KW - KOBV KW - KOBV-Projekt KW - Kooperativer Bibliotheksverbund Berlin-Brandenburg Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4399 ER - TY - GEN A1 - Grötschel, Martin A1 - Kuberek, Monika A1 - Lohrum, Stefan A1 - Lügger, Joachim A1 - Rusch, Beate T1 - Die KOBV-Suchmaschine geht in Routinebetrieb N2 - Im Herbst 1999 nimmt die KOBV-Suchmaschine, das technische "Herzstück" des KOBV, den Routinebetrieb auf. Nach einer kurzen Einführung in die politischen und rechtlichen Grundlagen des KOBV-Projektes werden in diesem Aufsatz die Funktionalitäten der KOBV-Suchmaschine, ihre Leistungen für Bibliotheksbenutzer und Bibliothekare, vorgestellt. Der Aufsatz schließt mit einem Überblick über den bisherigen Projektverlauf und der Erläuterung der wichtigsten Prinzipien des KOBV - Offenheit, Dezentralität und Heterogenität. T3 - ZIB-Report - SC-99-51 KW - Bibliotheksverbund KW - KOBV KW - KOBV-Projekt KW - KOBV-Suchmaschine KW - Kooperativer Bibliotheksverbund Berlin-Brandenburg KW - Suchmaschine Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4407 ER - TY - GEN A1 - Foupouagnigni, Mama A1 - Koepf, Wolfram A1 - Ronveaux, Andre T1 - Fourth Order Difference Equation for the Associated Classical Discrete Orthogonal Polynomials N2 - We derive the fourth order difference equation satisfied by the associated of order $\;r\;$ of the classical orthogonal polynomials of a discrete variable.\\The coefficients of this equation are given in terms of the polynomials $\; \sigma\;$ and $\;\tau\;$ which appear in the discrete Pearson equation $\;\;\Delta(\sigma\;\rho)=\tau\;\rho\;\;$ defining the weight $\;\rho(x)\;$ of the classical discrete orthogonal polynomials. T3 - ZIB-Report - SC-97-72 Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3419 ER - TY - GEN A1 - Lang, Jens A1 - Erdmann, Bodo A1 - Seebass, Martin T1 - Impact of Nonlinear Heat Transfer on Temperature Control in Regional Hyperthermia N2 - We describe an optimization process specially designed for regional hyperthermia of deep seated tumors in order to achieve desired steady--state temperature distributions. A nonlinear three--dimensional heat transfer model based on temperature--dependent blood perfusion is applied to predict the temperature. Using linearly implicit methods in time and adaptive multilevel finite elements in space, we are able to integrate efficiently the instationary nonlinear heat equation with high accuracy. Optimal heating is obtained by minimizing an integral object function which measures the distance between desired and model predicted temperatures. A sequence of minima is calculated from successively improved constant--rate perfusion models employing a damped Newton method in an inner iteration. We compare temperature distributions for two individual patients calculated on coarse and fine spatial grids and present numerical results of optimizations for a Sigma 60 Applicator of the BSD 2000 Hyperthermia System. T3 - ZIB-Report - SC-97-73 Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3426 ER - TY - GEN A1 - Hege, Hans-Christian A1 - Stalling, Detlev T1 - Fast LIC with Higher Order Filter Kernels N2 - Line integral convolution (LIC) has become a well-known and popular method for visualizing vector fields. The method works by convolving a random input texture along the integral curves of the vector field. In order to accelerate image synthesis significantly, an efficient algorithm has been proposed that utilizes pixel coherence in field line direction. This algorithm, called ``fast LIC'', originally was restricted to simple box-type filter kernels. Here we describe a generalization of fast LIC for piecewise polynomial filter kernels. Expanding the filter kernels in terms of truncated power functions allows us to exploit a certain convolution theorem. The convolution integral is expressed as a linear combination of repeated integrals (or repeated sums in the discrete case). Compared to the original algorithm the additional expense for using higher order filter kernels, e.g.\ of B-spline type, is very low. Such filter kernels produce smoother, less noisier results than a box filter. This is evident from visual investigation, as well as from analysis of pixel correlations. Thus, our method represents a useful extension of the fast LIC algorithm for the creation of high-quality LIC images. T3 - ZIB-Report - SC-97-74 Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3439 ER - TY - GEN A1 - Wolf, Thomas T1 - A Study of Genetic Algorithms solving a combinatorial Puzzle N2 - The suitability of Genetic Algorithms (GAs) to solve a combinatorial problem with only one solution is investigated. The dependence of the performance is studied for GA-hard and GA-soft fitness functions, both with a range of different parameter values and different encodings. T3 - ZIB-Report - SC-98-01 Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3445 ER - TY - GEN A1 - Böing, Harald A1 - Koepf, Wolfram T1 - Algorithms for q-hypergeometric Summation in Computer Algebra N2 - In this paper we present a short description of $q$-analogues of Gosper's, Zeilberger's, Petkov\v{s}ek's and related algorithms. Furthermore we introduce our corresponding MAPLE implementations and show how they can be applied to prove or even derive identities associated with $q$-series. T3 - ZIB-Report - SC-98-02 Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3453 ER - TY - GEN A1 - Deuflhard, Peter A1 - Huisinga, Wilhelm A1 - Fischer, Alexander A1 - Schütte, Christof T1 - Identification of Almost Invariant Aggregates in Reversible Nearly Uncoupled Markov Chains N2 - The topic of the present paper bas been motivated by a recent computational approach to identify chemical conformations and conformational changes within molecular systems. After proper discretization, the conformations show up as almost invariant aggregates in reversible nearly uncoupled Markov chains. Most of the former work on this subject treated the direct problem: given the aggregates, analyze the loose coupling in connection with the computation of the stationary distribution (aggregation/disaggregation techniques). In contrast to that the present paper focuses on the inverse problem: given the system as a whole, identify the almost invariant aggregates together with the associated transition probabilites. A rather simple and robust algorithm is suggested and illustrated by its application to the n-pentane molecule. T3 - ZIB-Report - SC-98-03 KW - essential molecular dynamics KW - nearly reducible KW - nearly completely decomposable KW - nearly uncoupled Markov chain KW - almost invariant aggregates KW - trans Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3469 ER - TY - GEN A1 - Schütte, Christof A1 - Fischer, Alexander A1 - Huisinga, Wilhelm A1 - Deuflhard, Peter T1 - A Hybrid Monte Carlo Method for Essential Molecular Dynamics N2 - Recently, a novel concept for the computation of essential features of Hamiltonian systems (such as those arising in molecular dynamics) has been proposed. The realization of that concept was based on subdivision techniques applied to the Frobenius--Perron operator for the dynamical system. The present paper suggests an alternative but related concept based on statistical mechanics, which allows to attack realistic molecular systems. In a first step, the frequency of conformational changes is characterized in statistical terms leading to the definition of some Markov operator $T$ that describes the corresponding transition probabilities within the canonical ensemble. In a second step, a discretization of $T$ via hybrid Monte Carlo techniques (based on short term subtrajectories only) is shown to lead to a stochastic matrix $P$. With these theoretical preparations, an identification algorithm for conformations is applicable (to be presented elsewhere). Numerical results for the n-pentane molecule are given and interpreted. T3 - ZIB-Report - SC-98-04 Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3474 ER - TY - GEN A1 - Wolf, Thomas A1 - Brandt, Andreas A1 - Mohammadzadeh, Majid T1 - Computer algebra algorithms and routines for the computation of conservation laws and fixing of gauge in differential expressions N2 - Three different approaches for the determination of conservation laws of differential equations are presented. For three corresponding REDUCE computer algebra programs CONLAW1/2/3 the necessary subroutines are discribed. One of them simplifies general solutions of overdetermined PDE systems so that all remaining free functions and constants correspond to independent conservation laws. It determines redundant functions and constants in differential expressions and is equally useful for the determination of symmetries or the fixing of gauge freedom in differential expressions. T3 - ZIB-Report - SC-98-05 Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3482 ER - TY - GEN A1 - Foupouagnigni, Mama A1 - Ronveaux, Andre A1 - Koepf, Wolfram T1 - Fourth-Order q-Difference Equation for the First Associated of the q-Classical Orthogonal Polynomials N2 - We derive the fourth order $q$-difference equation satisfied by the first associated of the $q$-classical orthogonal polynomials. The coefficients of this equation are given in terms of the polynomials $\; \sigma\;$ and $\;\tau\;$ which appear in the $q$-Pearson difference equation $\;\; D_q(\sigma\,\rho)=\tau\,\rho\;$ defining the weight $\rho$ of the $q$-classical orthogonal polynomials inside the $q$-Hahn tableau. T3 - ZIB-Report - SC-98-06 KW - q-Orthogonal polynomials KW - Fourth order q-difference equation Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3490 ER - TY - GEN A1 - Ascheuer, Norbert A1 - Grötschel, Martin A1 - Kamin, Nicola A1 - Rambau, Jörg T1 - Combinatorial Online Optimization in Practice N2 - This paper gives a short introduction into combinatorial online optimization. It explains a few evaluation concepts of online algorithms, such as competitiveness, and discusses limitations in their application to real--world problems. The main focus, however, is a survey of combinatorial online problems coming up in practice, in particular, in large scale material flow and flexible manufacturing systems. T3 - ZIB-Report - SC-98-07 KW - Online optimization KW - combinatorial optimization KW - real-world problems Y1 - 1998 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3508 ER - TY - GEN A1 - Reich, Sebastian T1 - Preservation of Adiabatic Invariants under Symplectic Discretization N2 - Symplectic methods, like the Verlet method, are a standard tool for the long term integration of Hamiltonian systems as they arise, for example, in molecular dynamics. One of the reasons for the popularity of symplectic methods is the conservation of energy over very long periods of time up to small fluctuations that scale with the order of the method. In this paper, we discuss a qualitative feature of Hamiltonian systems with separated time scales that is also preserved under symplectic discretization. Specifically, highly oscillatory degrees of freedom often lead to almost preserved quantities (adiabatic invariants). Using recent results from backward error analysis and normal form theory, we show that a symplectic method, like the Verlet method, preserves those adiabatic invariants. We also discuss step-size restrictions necessary to maintain adiabatic invariants in practical computations. T3 - ZIB-Report - SC-97-52 Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3210 ER - TY - GEN A1 - Barth, Eric A1 - Leimkuhler, Benedict A1 - Reich, Sebastian T1 - A Time-Reversible Variable-Stepsize Integrator for Constrained Dynamics N2 - This article considers the design and implementation of variable-timestep methods for simulating holonomically constrained mechanical systems. Symplectic variable stepsizes are briefly discussed, we then consider time-reparameterization techniques employing a time-reversible (symmetric) integration method to solve the equations of motion. We give several numerical examples, including a simulation of an elastic (inextensible, unshearable) rod undergoing large deformations and collisions with the sides of a bounding box. Numerical experiments indicate that adaptive stepping can significantly smooth the numerical energy and improve the overall efficiency of the simulation. T3 - ZIB-Report - SC-97-53 Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3220 ER -