TY - GEN A1 - Brandt, Andreas A1 - Brandt, Manfred T1 - Individual Overflow and Freed Carried Traffics for a Link with Trunk Reservation N2 - Two traffic streams $\Phi_1$, $\Phi_2$ are offered a link. The calls of $\Phi_i$ require exponential holding times with parameter $\mu$ and are accepted if less than $C_i$ trunks are occupied. Approximating the $\Phi_i$ by appropriate renewal processes meeting their first two moments, defined as the moments of the numbers of calls in virtual links of infinite capacity to which the traffic streams as freed traffics are virtually directed and where the calls get fresh exponential i.i.d.\ holding times with parameter $\mu$, stable recursive algorithms of complexity $O(\max(C_1,C_2))$ are derived for the first two defined as above moments of the individual overflow and freed carried traffics. The results offer a unified handling of both overflow and carried traffics in circuit switching networks with trunk reservation, providing a basis for new two-moment network dimensioning algorithms. T3 - ZIB-Report - 01-35 KW - trunk reservation KW - overflow traffic KW - freed carried traffic KW - factorial moments KW - peakedness KW - two-moment method KW - circuit switching network Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6615 ER - TY - GEN A1 - Kuberek, Monika T1 - Der KOBV - eine regionale Service-Einrichtung für Nutzer und Bibliothekare N2 - Dem vorliegenden Aufsatz liegt ein Vortrag zugrunde, den die Verfasserin auf der Ersten Gemeinsamen Fachtagung der DBV-Landesverbände Berlin und Brandenburg "Wir machen den Weg frei : Fusionen - Kooperationen in Berlin und Brandenburg" am 17. Oktober 2001 gehalten hat, in der Vortragsreihe "Möglichkeiten und Grenzen von Ausleih- und bibliographischen Verbünden - VÖB Berlin, VÖB Brandenburg, KOBV". Der Kooperative Bibliotheksverbund Berlin-Brandenburg (KOBV) ist angetreten, um auf der Basis neuer Technologien zeitgemäße, nutzerorientierte Dienstleistungen für den Informationsbereich zu entwickeln und die Informationsinfrastruktur in der Region Berlin-Brandenburg neu zu organisieren. Dabei setzt der KOBV insbesondere auf das Internet. Die Verfasserin beschreibt die einzelnen Stufen, in denen die Dienste des KOBV aufgebaut wurden und kontinuierlich weiter ausgebaut werden. Dabei zeigt sie Vorteile auf, die Nutzern und Bibliotheken durch den Verbund entstehen, und lotet gleichzeitig die Grenzen aus, die dem Verbund gesetzt sind. T3 - ZIB-Report - 01-36 KW - Bibliotheksverbund KW - KOBV KW - Kooperativer Bibliotheksverbund Berlin-Brandenburg KW - Service-Einrichtung KW - Service-Einrichtung KOBV KW - Verbund-Dienstleistu Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6620 ER - TY - GEN A1 - Helmberg, Christoph T1 - Numerical Evaluation of SBmethod N2 - We report numerical results for SBmethod --- a publically available implementation of the spectral bundle method --- applied to the 7$^{th}$ DIMACS challenge test sets that are semidefinite relaxations of combinatorial optimization problems. The performance of the code is heavily influenced by parameters that control bundle update and eigenvalue computation. Unfortunately, no mathematically sound guidelines for setting them are known. Based on our experience with SBmethod, we propose heuristics for dynamically updating the parameters as well as a heuristc for improving the starting point. These are now the default settings of SBmethod Version 1.1. We compare their performance on the DIMACS instances to our previous best choices for Version 1.0. SBmethod Version 1.1 is also part of the independent DIMACS benchmark by H.~Mittelmann. Based on these results we try to analyze strengths and weaknesses of our approach in comparison to other codes for large scale semidefinite programming. T3 - ZIB-Report - 01-37 KW - semidefinite programming KW - large scale methods KW - computational KW - semidefinite relaxations Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6637 ER - TY - GEN A1 - Koster, Arie M.C.A. A1 - Bodlaender, Hans L. A1 - Hoesel, Stan P.M. van T1 - Treewidth: Computational Experiments N2 - Many {\cal NP}-hard graph problems can be solved in polynomial time for graphs with bounded treewidth. Equivalent results are known for pathwidth and branchwidth. In recent years, several studies have shown that this result is not only of theoretical interest but can successfully be applied to find (almost) optimal solutions or lower bounds for diverse optimization problems. To apply a tree decomposition approach, the treewidth of the graph has to be determined, independently of the application at hand. Although for fixed $k$, linear time algorithms exist to solve the decision problem ``treewidth $\leq k$'', their practical use is very limited. The computational tractability of treewidth has been rarely studied so far. In this paper, we compare four heuristics and two lower bounds for instances from applications such as the frequency assignment problem and the vertex coloring problem. Three of the heuristics are based on well-known algorithms to recognize triangulated graphs. The fourth heuristic recursively improves a tree decomposition by the computation of minimal separating vertex sets in subgraphs. Lower bounds can be computed from maximal cliques and the minimum degree of induced subgraphs. A computational analysis shows that the treewidth of several graphs can be identified by these methods. For other graphs, however, more sophisticated techniques are necessary. T3 - ZIB-Report - 01-38 KW - treewidth KW - heuristics KW - lower bounds KW - computations Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6644 ER - TY - GEN A1 - Bodlaender, Hans L. A1 - Koster, Arie M.C.A. A1 - Eijkhof, Frank van den A1 - Gaag, Linda C. van der T1 - Pre-processing for Triangulation of Probabilistic Networks N2 - The currently most efficient algorithm for inference with a probabilistic network builds upon a triangulation of a network's graph. In this paper, we show that pre-processing can help in finding good triangulations for probabilistic networks, that is, triangulations with a minimal maximum clique size. We provide a set of rules for stepwise reducing a graph, without losing optimality. This reduction allows us to solve the triangulation problem on a smaller graph. From the smaller graph's triangulation, a triangulation of the original graph is obtained by reversing the reduction steps. Our experimental results show that the graphs of some well-known real-life probabilistic networks can be triangulated optimally just by preprocessing; for other networks, huge reductions in their graph's size are obtained. T3 - ZIB-Report - 01-39 KW - triangulation KW - treewidth KW - probabilistic networks KW - pre-processing Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6655 ER - TY - GEN A1 - Aardal, Karen I. A1 - Hoesel, Stan P.M. van A1 - Koster, Arie M.C.A. A1 - Mannino, Carlo A1 - Sassano, Antonio T1 - Models and Solution Techniques for Frequency Assignment Problems N2 - {\begin{rawhtml} Revised Version unter http://dx.doi.org/10.1007/s10479-007-0178-0 \end{rawhtml}} Wireless communication is used in many different situations such as mobile telephony, radio and TV broadcasting, satellite communication, and military operations. In each of these situations a frequency assignment problem arises with application specific characteristics. Researchers have developed different modelling ideas for each of the features of the problem, such as the handling of interference among radio signals, the availability of frequencies, and the optimization criterion. This survey gives an overview of the models and methods that the literature provides on the topic. We present a broad description of the practical settings in which frequency assignment is applied. We also present a classification of the different models and formulations described in the literature, such that the common features of the models are emphasized. The solution methods are divided in two parts. Optimization and lower bounding techniques on the one hand, and heuristic search techniques on the other hand. The literature is classified according to the used methods. Again, we emphasize the common features, used in the different papers. The quality of the solution methods is compared, whenever possible, on publicly available benchmark instances. T3 - ZIB-Report - 01-40 KW - frequency assignment Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6667 ER - TY - GEN A1 - Kuberek, Monika A1 - Lill, Monika A1 - Litsche, Stefan A1 - Lohrum, Stefan A1 - Lügger, Joachim A1 - Otto, Dagmar A1 - Rusch, Beate T1 - Entwicklungsprojekt "KOBV-Informationsportal" : Teilprojekte der 1. Stufe N2 - Die KOBV-Suchmaschine hat seit ihrer Inbetriebnahme Ende 1999 entscheidend zur Verbesserung der Informationsinfrastruktur in Berlin und Brandenburg beigetragen. Auf der Basis der offenen Plattform KOBV-Suchmaschine wird die KOBV-Zentrale gemeinsam mit den Bibliotheken in den nächsten Jahren das Dienstleistungsangebot des KOBV und seiner Bibliotheken kontinuierlich erweitern. Dabei sollen die Prinzipien des KOBV - Offenheit, Heterogenität und Dezentralität auf technischer und organisatorischer Ebene - gewahrt bleiben. Die einzelnen KOBV-Bibliotheken werden sich mit ihren Angeboten in unterschiedlicher Weise im Web positionieren. Die Integration auf regionaler Ebene kann und soll die lokalen Angebote nicht künstlich vereinheitlichen. Das kooperative Portal, das in der Region aufgebaut wird, ist als System geplant, in dem zentrales Portal und lokale Portale nicht hierarchisch einander zugeordnet, sondern miteinander vernetzt sind. Das \glqq KOBV-Informationsportal \grqq soll in der KOBV-Zentrale im Rahmen eines wissenschaftlichen Projektes von Mitte 2001 bis Ende 2003 aufgebaut werden. Das vorliegende Papier gibt einen ersten allgemeinen Einblick, welche Funktionen das \glqq KOBV-Informationsporta \grqq umfassen soll und stellt die Teilprojekte der 1. Stufe vor. T3 - ZIB-Report - 01-41 KW - Bibliotheksverbund KW - Digitale Bibliothek KW - KOBV KW - KOBV-Informationsportal KW - Kooperativer Bibliotheksverbund Berlin-Brandenburg KW - Portal Y1 - 2002 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6678 ER - TY - GEN A1 - Hohage, Thorsten A1 - Schmidt, Frank A1 - Zschiedrich, Lin T1 - A new method for the solution of scattering problems N2 - We present a new efficient algorithm for the solution of direct time-harmonic scattering problems based on the Laplace transform. This method does not rely on an explicit knowledge of a Green function or a series representation of the solution, and it can be used for the solution of problems with radially symmetric potentials and problems with waveguides. The starting point is an alternative characterization of outgoing waves called \emph{pole condition}, which is equivalent to Sommerfeld's radiation condition for problems with radially symmetric potentials. We obtain a new representation formula, which can be used for a numerical evaluation of the exterior field in a postprocessing step. Based on previous theoretical studies, we discuss the numerical realization of our algorithm and compare its performance to the PML method. T3 - ZIB-Report - 02-01 KW - transparent boundary conditions KW - inhomogeneous exterior domains KW - Laplace transform Y1 - 2002 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6683 ER - TY - GEN A1 - Pfeifle, Julian A1 - Rambau, Jörg T1 - Computing Triangulations Using Oriented Matroids N2 - Oriented matroids are combinatorial structures that encode the combinatorics of point configurations. The set of all triangulations of a point configuration depends only on its oriented matroid. We survey the most important ingredients necessary to exploit oriented matroids as a data structure for computing all triangulations of a point configuration, and report on experience with an implementation of these concepts in the software package TOPCOM. Next, we briefly overview the construction and an application of the secondary polytope of a point configuration, and calculate some examples illustrating how our tools were integrated into the {\sc polymake} framework. T3 - ZIB-Report - 02-02 KW - triangulation KW - oriented matroid KW - software KW - chirotope KW - circuit KW - cocircuit KW - symmetry KW - regular KW - secondary polytope KW - hypergeometric function Y1 - 2002 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6692 ER - TY - GEN A1 - Wagler, Annegret T1 - Relaxing Perfectness: Which Graphs are 'Almost' Perfect? N2 - For all perfect graphs, the stable set polytope STAB$(G)$ coincides with the fractional stable set polytope QSTAB$(G)$, whereas STAB$(G) \subset$ QSTAB$(G)$ holds iff $G$ is imperfect. Padberg asked in the early seventies for ``almost'' perfect graphs. He characterized those graphs for which the difference between STAB$(G)$ and QSTAB$(G)$ is smallest possible. We develop this idea further and define three polytopes between STAB$(G)$ and QSTAB$(G)$ by allowing certain sets of cutting planes only to cut off all the fractional vertices of QSTAB$(G)$. The difference between QSTAB$(G)$ and the largest of the three polytopes coinciding with STAB$(G)$ gives some information on the stage of imperfectness of the graph~$G$. We obtain a nested collection of three superclasses of perfect graphs and survey which graphs are known to belong to one of those three superclasses. This answers the question: which graphs are ``almost'' perfect? T3 - ZIB-Report - 02-03 KW - perfect graph KW - stable set polytope KW - relaxations Y1 - 2002 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6700 ER - TY - GEN A1 - Kähler, Ralf A1 - Simon, Mark A1 - Hege, Hans-Christian T1 - Fast Volume Rendering of Sparse High-Resolution Datasets Using Adaptive Mesh Refinement Hierarchies N2 - In this paper we present an algorithm that accelerates 3D texture-based volume rendering of large and sparse data sets. A hierarchical data structure (known as AMR tree) consisting of nested uniform grids is employed in order to efficiently encode regions of interest. The hierarchies resulting from this kind of space partitioning yield a good balance between the amount of volume to render and the number of texture bricks -- a prerequisite for fast rendering. Comparing our approach to an octree based algorithm we show that our algorithm increases rendering performance significantly for sparse data. A further advantage is that less parameter tuning is necessary. T3 - ZIB-Report - 01-25 KW - scalar field visualization KW - volume visualization KW - volume rendering KW - 3D texture mapping KW - hierarchical space partitioning KW - AMR tree KW - octree KW - spar Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6516 ER - TY - GEN A1 - Helmberg, Christoph T1 - A Cutting Plane Algorithm for Large Scale Semidefinite Relaxations N2 - The recent spectral bundle method allows to compute, within reasonable time, approximate dual solutions of large scale semidefinite quadratic 0-1 programming relaxations. We show that it also generates a sequence of primal approximations that converge to a primal optimal solution. Separating with respect to these approximations gives rise to a cutting plane algorithm that converges to the optimal solution under reasonable assumptions on the separation oracle and the feasible set. We have implemented a practical variant of the cutting plane algorithm for improving semidefinite relaxations of constrained quadratic 0-1 programming problems by odd-cycle inequalities. We also consider separating odd-cycle inequalities with respect to a larger support than given by the cost matrix and present a heuristic for selecting this support. Our preliminary computational results for max-cut instances on toroidal grid graphs and balanced bisection instances indicate that warm start is highly efficient and that enlarging the support may sometimes improve the quality of relaxations considerably. T3 - ZIB-Report - 01-26 KW - bisection KW - equicut KW - max-cut KW - semidefinite programming KW - spectral bundle method KW - subgradient method KW - quadratic 0-1 programming Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6527 ER - TY - GEN A1 - Grötschel, Martin T1 - Telota - was soll das? N2 - Telota ist ein Kunstwort, das für alle Aktivitäten der Berlin-Brandenburgischen Akademie der Wissenschaften steht, die der Förderung von Forschung, Kommunikation und Präsentation durch elektronische Medien dienen. In diesem Artikel werden die Entstehung des Telota-Projektes geschildert und die Ziele diskutiert, die mit diesem Projekt erreicht werden sollen. Es geht darum, moderne Informationstechnik bewusst, geplant und nachhaltig für alle Belange der {\rm BBAW} einzusetzen. Informationstechnische Werkzeuge sollen für die wissenschaftliche Arbeit effizient genutzt werden; die Information nach innen und nach außen soll deutlich verbessert werden; eine bessere Kommunikationsinfrastuktur soll die Zusammenarbeit fördern. T3 - ZIB-Report - 01-27 KW - BBAW KW - Telota-Projekt KW - elektronische Publikation Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6538 ER - TY - GEN A1 - Grötschel, Martin T1 - Empfehlungen des Wissenschaftsrates zur digitalen Informationsversorgung durch Hochschulbibliotheken N2 - Der Wissenschaftsrat hat in seiner Juli-Sitzung 2001 \glqq Empfehlungen zur digitalen Informationsversorgung durch Hochschulbibliotheken \grqq verabschiedet. Einige der Vorschläge des Wissenschaftsrates können, falls sie von den angesprochenen Institutionen aufgenommen werden, zu einer nachhaltigen Veränderung der wissenschaftlichen Informationslandschaft führen. In meinem kurzen Kommentar zu diesem Papier möchte ich auf einige dieser Anregungen hinweisen. T3 - ZIB-Report - 01-28 KW - Wissenschaftsrat KW - digitale Informationsversorgung KW - Hochschulbibliotheken Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6546 ER - TY - GEN A1 - Grötschel, Martin T1 - Mein digitaler Traum N2 - Von welcher "Informationsumwelt" träumt jemand, der für seine wissenschaftliche (und sonstige) Arbeit digitale Informationstechnologie intensiv einsetzt? In diesem Artikel beschreibe ich meinen "digitalen Traum". Er ist ganz einfach zu formulieren:"Ich will alles und zwar sofort, jederzeit, "überall" und kostenlos zur Verfügung haben." Ich schildere, was davon heute schon (fast) realisiert ist und was noch fehlt. Ich skizziere einige zentrale Schwierigkeiten der vollständigen Realisierung und skizziere mögliche Lösungen. T3 - ZIB-Report - 01-29 KW - digitale Informationstechnologie KW - digitale Information KW - BBAW Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6558 ER - TY - GEN A1 - Kähler, Ralf A1 - Hege, Hans-Christian T1 - Interactive Volume Rendering of Adaptive Mesh Refinement Data N2 - Many phenomena in nature and engineering happen simultaneously on rather diverse spatial and temporal scales, i.e.\ exhibit a multi-scale character. Therefore various hierarchical data structures and numerical schemes have been devised to represent quantitatively such phenomena. A special numerical multilevel technique, associated with a particular hierarchical data structure, is so-called Adaptive Mesh Refinement (AMR). This scheme achieves locally very high spatial and temporal resolutions. Due to its popularity, many scientists are in need of interactive visualization tools for AMR data. In this article we present a 3D texture-based volume rendering algorithm for AMR data, that directly utilizes the hierarchical structure. Thereby interactive rendering even for large data sets is achieved. In particular the problems of interpolation artifacts, opacity corrections, and texture memory limitations are addressed. The algorithm's value in practice is demonstrated with simulation and image data. T3 - ZIB-Report - 01-30 KW - Scalar field visualization KW - multiresolution volume rendering KW - AMR hierarchies KW - 3D texture mapping Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6561 ER - TY - GEN A1 - Kober, Cornelia A1 - Sader, Robert A1 - Zeilhofer, Hans-Florian A1 - Prohaska, Steffen A1 - Zachow, Stefan A1 - Deuflhard, Peter T1 - Anisotrope Materialmodellierung für den menschlichen Unterkiefer N2 - Im Rahmen der biomechanischen Simulation knöcherner Organe ist die Frage nach einer befriedigenden Materialbeschreibung nach wie vor ungelöst. Computertomographische Datensätze liefern eine räumliche Verteilung der (Röntgen-)Dichte und ermöglichen damit eine gute Darstellung der individuellen Geometrie. Weiter können die verschiedenen Materialbestandteile des Knochens, Spongiosa und Kortikalis, voneinander getrennt werden. Aber die richtungsabängige Information der Materialanisotropie ist verloren. In dieser Arbeit wird ein Ansatz für eine anisotrope Materialbeschreibung vorgestellt, die es ermöglicht, den Einfluss der individuellen knöchernen Struktur auf das makroskopische Materialverhalten abzuschätzen. T3 - ZIB-Report - 01-31 KW - menschlicher Unterkiefer KW - Simulation mit der Methode der finiten Elemente KW - innerer Aufbau des Knochens KW - anisotrope Elastizität Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6574 ER - TY - GEN A1 - Zöckler, Malte A1 - Rein, Karlheinz A1 - Brandt, Robert A1 - Stalling, Detlev A1 - Hege, Hans-Christian T1 - Creating Virtual Insect Brains with Amira N2 - By combining techniques of preparation, histology, confocal microscopy, data visualization and data processing, we have created and recently published a standard brain model for drosophila and honey bee brains. This report describes the algorithms and implementation of the corresponding software modules. At the same time it serves as a user's guide for scientist who want to reproduce the results for differerent species or mutants. T3 - ZIB-Report - 01-32 KW - visualization KW - anatomical atlas Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6589 ER - TY - GEN A1 - Ilgenfritz, Ernst-Michael A1 - Kerler, Werner A1 - Müller-Preussker, Michael A1 - Stüben, Hinnerk T1 - Parallel tempering in full QCD with Wilson fermions N2 - We study the performance of QCD simulations with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering on $10^4$ and $12^4$ lattices. In order to compare tempered with standard simulations, covariance matrices between sub-ensembles have to be formulated and evaluated using the general properties of autocorrelations of the parallel tempering algorithm. We find that rendering the hopping parameter $\kappa$ dynamical does not lead to an essential improvement. We point out possible reasons for this observation and discuss more suitable ways of applying parallel tempering to QCD. T3 - ZIB-Report - 01-33 KW - QCD KW - parallel tempering KW - correlation analysis Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6593 ER - TY - GEN A1 - Sokolov, Vladimir V. A1 - Wolf, Thomas T1 - Classification of integrable polynomial vector evolution equations N2 - Several classes of systems of evolution equations with one or two vector unknowns are considered. We investigate also systems with one vector and one scalar unknown. For these classes all equations having the simplest higher symmetry are listed. T3 - ZIB-Report - 01-34 Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6601 ER - TY - GEN A1 - Hohage, Thorsten A1 - Schmidt, Frank T1 - On the Numerical Solution of Nonlinear Schrödinger type equations in fiber optics N2 - The aim of this paper is to develop fast methods for the solution of nonlinear Schrödinger type equations in fiber optics. Using the method of lines we have to solve a stiff system of ordinary differential equations where the eigenvalues of the Jacobian are close to the imaginary axis. This is usually done by a Split Step method. Here we consider the extrapolation of Split Step methods with adaptive order and step size control. For more complicated nonlinearities, in particular stimulated Raman scattering, Split Step methods are less efficient since symmetry is either destroyed or requires much additional effort. In this case we use implicit Runge Kutta formulas of Gauß type. The key point for the efficient implementation of these methods is that the system of nonlinear algebraic equations can be solved without setting up the Jacobian. The proposed methods are compared to other methods, in particular exponential integrators, the method of Marcuse, and the method of Blow and Wood. T3 - ZIB-Report - 02-04 KW - nonlinear Schroedinger equation KW - split step methods KW - extrapolation KW - collocation methods Y1 - 2002 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6715 ER - TY - GEN A1 - Krumke, Sven A1 - Rambau, Jörg T1 - Probieren geht über Studieren? Entscheidungshilfen für kombinatorische Online-Optimierungsprobleme in der innerbetrieblichen Logistik N2 - Die Automatisierung von innerbetrieblicher Logistik erfordert -- über die physikalische Steuerung von Geräten hinaus -- auch eine effiziente Organisation der Transporte: ein Aufgabenfeld der kombinatorischen Optimierung. Dieser Artikel illustriert anhand von konkreten Aufgabenstellungen die Online-Problematik (unvollständiges Wissen) sowie die Echtzeit-Problematik (beschränkte Rechenzeit), auf die man in der innerbetrieblichen Logistik trifft. Der Text gibt einen Überblick über allgemeine Konstruktionsprinzipien für Online-Algorithmen und Bewertungsmethoden, die bei der Entscheidung helfen, welche Algorithmen für eine vorliegende Problemstellung geeignet sind. T3 - ZIB-Report - 02-05 KW - Logistik KW - Hochregallagerbediengeräte KW - Kommissioniermobile KW - Aufzüge KW - Online-Optimierung KW - Echtzeit-Optimierung KW - Simulation KW - kompetitive Analyse Y1 - 2002 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6723 ER - TY - GEN A1 - Reinefeld, Alexander A1 - Stüben, Hinnerk A1 - Schintke, Florian A1 - Din, George T1 - GuiGen: A Toolset for Creating Customized Interfaces for Grid User Communities N2 - \textsf{\itshape{GuiGen}} is a comprehensive set of tools for creating customized graphical user interfaces (GUIs). It draws from the concept of computing portals, which are here seen as interfaces to application-specific computing services for user communities. While \textsf{\itshape{GuiGen}} was originally designed for the use in computational grids, it can be used in client/server environments as well. Compared to other GUI generators, \textsf{\itshape{GuiGen}} is more versatile and more portable. It can be employed in many different application domains and on different target platforms. With \textsf{\itshape{GuiGen}}, application experts (rather than computer scientists) are able to create their own individually tailored GUIs. T3 - ZIB-Report - 02-06 KW - Grid computing KW - customized user interfaces KW - grid user communities KW - web portals KW - XML Y1 - 2002 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-6737 ER -