@misc{Groetschel2001, author = {Gr{\"o}tschel, Martin}, title = {Telota - was soll das?}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6538}, number = {01-27}, year = {2001}, abstract = {Telota ist ein Kunstwort, das f{\"u}r alle Aktivit{\"a}ten der Berlin-Brandenburgischen Akademie der Wissenschaften steht, die der F{\"o}rderung von Forschung, Kommunikation und Pr{\"a}sentation 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 f{\"u}r alle Belange der {\rm BBAW} einzusetzen. Informationstechnische Werkzeuge sollen f{\"u}r die wissenschaftliche Arbeit effizient genutzt werden; die Information nach innen und nach außen soll deutlich verbessert werden; eine bessere Kommunikationsinfrastuktur soll die Zusammenarbeit f{\"o}rdern.}, language = {de} } @misc{Groetschel2001, author = {Gr{\"o}tschel, Martin}, title = {Empfehlungen des Wissenschaftsrates zur digitalen Informationsversorgung durch Hochschulbibliotheken}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6546}, number = {01-28}, year = {2001}, abstract = {Der Wissenschaftsrat hat in seiner Juli-Sitzung 2001 \glqq Empfehlungen zur digitalen Informationsversorgung durch Hochschulbibliotheken \grqq verabschiedet. Einige der Vorschl{\"a}ge des Wissenschaftsrates k{\"o}nnen, falls sie von den angesprochenen Institutionen aufgenommen werden, zu einer nachhaltigen Ver{\"a}nderung der wissenschaftlichen Informationslandschaft f{\"u}hren. In meinem kurzen Kommentar zu diesem Papier m{\"o}chte ich auf einige dieser Anregungen hinweisen.}, language = {de} } @misc{Groetschel2001, author = {Gr{\"o}tschel, Martin}, title = {Mein digitaler Traum}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6558}, number = {01-29}, year = {2001}, abstract = {Von welcher "Informationsumwelt" tr{\"a}umt jemand, der f{\"u}r 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, "{\"u}berall" und kostenlos zur Verf{\"u}gung haben." Ich schildere, was davon heute schon (fast) realisiert ist und was noch fehlt. Ich skizziere einige zentrale Schwierigkeiten der vollst{\"a}ndigen Realisierung und skizziere m{\"o}gliche L{\"o}sungen.}, language = {de} } @misc{Helmberg2001, author = {Helmberg, Christoph}, title = {A Cutting Plane Algorithm for Large Scale Semidefinite Relaxations}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6527}, number = {01-26}, year = {2001}, abstract = {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.}, language = {en} } @misc{Steinbach2001, author = {Steinbach, Marc}, title = {General Information Constraints in Stochastic Programs}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6502}, number = {01-24}, year = {2001}, abstract = {Scenario tree models of stochastic programs arise naturally under standard nonanticipativity assumptions. We demonstrate how tree-sparse programs cover the general case, with \emph{arbitrary} information constraints. Detailed examples and intuitive interpretations illuminate the basic thoughts behind the abstract but elementary construction.}, language = {en} } @misc{KaehlerSimonHege2001, author = {K{\"a}hler, Ralf and Simon, Mark and Hege, Hans-Christian}, title = {Fast Volume Rendering of Sparse High-Resolution Datasets Using Adaptive Mesh Refinement Hierarchies}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6516}, number = {01-25}, year = {2001}, abstract = {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.}, language = {en} } @misc{HohageSchmidtZschiedrich2001, author = {Hohage, Thorsten and Schmidt, Frank and Zschiedrich, Lin}, title = {Solving time-harmonic scattering problems based on the pole condition: Convergence of the PML method}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6494}, number = {01-23}, year = {2001}, abstract = {In this paper we study the PML method for Helmholtz-type scattering problems with radially symmetric potential. The PML method consists in surrounding the computational domain by a \textbf{P}erfectly \textbf{M}atched sponge \textbf{L}ayer. We prove that the approximate solution obtained by the PML method converges exponentially fast to the true solution in the computational domain as the thickness of the sponge layer tends to infinity. This is a generalization of results by Lassas and Somersalo based on boundary integral eqaution techniques. Here we use techniques based on the pole condition instead. This makes it possible to treat problems without an explicitly known fundamental solution.}, language = {en} } @misc{KrumkeRambauTorres2001, author = {Krumke, Sven and Rambau, J{\"o}rg and Torres, Luis Miguel}, title = {Real-Time Dispatching of Guided and Unguided Automobile Service Units with Soft Time Windows}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6484}, number = {01-22}, year = {2001}, abstract = {Given a set of service requests (events), a set of guided servers (units), and a set of unguided service contractors (conts), the vehicle dispatching problem {\sl vdp} is the task to find an assignment of events to units and conts as well as tours for all units starting at their current positions and ending at their home positions (dispatch) such that the total cost of the dispatch is minimized. The cost of a dispatch is the sum of unit costs, cont costs, and event costs. Unit costs consist of driving costs, service costs and overtime costs; cont costs consist of a fixed cost per service; event costs consist of late costs linear in the late time, which occur whenever the service of the event starts later than its deadline. The program \textsf{ZIBDIP} based on dynamic column generation and set partitioning yields solutions on heavy-load real-world instances (215 events, 95 units) in less than a minute that are no worse than 1\\% from optimum on state-of-the-art personal computers.}, language = {en} } @misc{Otto2001, author = {Otto, Dagmar}, title = {Informationsportale und Digitale Bibliotheken}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6479}, number = {01-21}, year = {2001}, abstract = {Im ersten Teil des folgenden Aufsatzes werden allgemeine {\"U}berlegungen zur Entwicklung von Bibliotheken hin zu Informationsvermittlungsstellen f{\"u}r sowohl elektronische wie auch gedruckte Medien angestellt. Basierend auf den Ergebnissen der Evaluation digitaler Bibliotheken und Informationsportale in Deutschland wird ein erster Kriterienkatalog f{\"u}r ein Verbund-Informationsportal f{\"u}r den Kooperativen Bibliotheksverbund Berlin-Brandenburg entwickelt. Im Anhang befindet sich der Statusbericht {\"u}ber Informationsportale und digitale Bibliotheken in Deutschland. Dazu wurden sieben digitale Bibliotheken auf Verbundebene und 21 Bibliotheken nach Bundesl{\"a}ndern evaluiert.}, language = {de} } @misc{Koch2001, author = {Koch, Thorsten}, title = {ZIMPL User Guide}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-6466}, number = {01-20}, year = {2001}, abstract = {{\sc Zimpl} is a little language to translate the mathematical model of a problem into a linear or (mixed-)integer mathematical program expressed in {\tt lp} or {\tt mps} file format which can be read by a LP or MIP solver.}, language = {en} }