@misc{Zumbusch, author = {Zumbusch, Gerhard}, title = {Adaptive h-p approximation procedures, graded meshes and anisotropic refinement for Numerical Quadrature}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-1905}, number = {SC-95-24}, abstract = {A set of adaptive algorithms for quadrature on multi-dimensional polyhedral domains is presented. Several kinds of refinement are discussed, covering local improvement of quadrature order and splitting the domain into sub-domains, resulting in isotropic, graded or anisotropic grids. The algorithms are pure local heuristics using no a priori knowledge or tuning parameters. This approach was motivated by results from finite element theory for optimal approximation results. Numerical experiments show the optimality of pure local greedy-like algorithms for singularity-type functions typically occurring in finite element computations.}, language = {en} } @misc{Zumbusch, author = {Zumbusch, Gerhard}, title = {Symmetric Hierarchical Polynomials for the h-p-Version of Finite Elements.}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-1275}, number = {SC-93-32}, abstract = {Adaptive numerical methods using the \$h\$-\$p\$-version of finite elements require special kinds of shape functions. Desirable properties of them are symmetry, hierarchy and simple coupling. In a first step it is demonstrated that for standard polynomial vector spaces not all of these features can be obtained simultaneously. However, this is possible if these spaces are extended. Thus a new class of polynomial shape functions is derived, which is well-suited for the \$p\$- and \$h\$-\$p\$-version of finite elements on unstructured simplices. The construction is completed by minimizing the condition numbers of the arising finite element matrices. The new shape functions are compared with standard functions widely used in the literature.}, language = {en} } @misc{Zuse, author = {Zuse, Konrad}, title = {Cellular Structured Space (Rechnender Raum) and Physical Phenomena.}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-5039}, number = {TR-93-12}, abstract = {The problem of nonlocal correlation and symmetry in space is of great importance in physical phenomena like the \underline{Einstein-Poloski-Rosen-Paradox} and others. It is shown that in Cellular Automata (Rechnender Raum) the structure of the space offers solutions for such problems.}, language = {en} } @misc{Zuse, author = {Zuse, Konrad}, title = {Discrete Mathematics and Rechnender Raum (Computing Space) -Part 1-. Cellular Structured Space (Rechnender Raum) and Physical Phenomena -Part 2-.}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-5156}, number = {TR-94-10}, abstract = {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{{\"a}}t Berlin in March 1994. To complete this lecture, a slightly modified version of TR 93-12 is appended.}, language = {en} } @misc{Zwingel, type = {Master Thesis}, author = {Zwingel, Oliver}, title = {Die Cross-Entropy-Methode f{\"u}r stochastische Optimierungsprobleme}, language = {de} } @phdthesis{Zymolka, author = {Zymolka, Adrian}, title = {Design of Survivable Optical Networks by Mathematical Optimization}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-10408}, abstract = {Abstract The cost-efficient design of survivable optical telecommunication networks is the topic of this thesis. In cooperation with network operators, we have developed suitable concepts and mathematical optimization methods to solve this comprehensive planning task in practice. Optical technology is more and more employed in modern telecommunication networks. Digital information is thereby transmitted as short light pulses through glass fibers. Moreover, the optical medium allows for simultaneous transmissions on a single fiber by use of different wavelengths. Recent optical switches enable a direct forwarding of optical channels in the network nodes without the previously required signal retransformation to electronics. Their integration creates ongoing optical connections,which are called lightpaths. We study the problem of finding cost-efficient configurations of optical networks which meet specified communication requirements. A configuration comprises the determination of all lightpaths to establish as well as the detailed allocation of all required devices and systems. We use a flexible modeling framework for a realistic representation of the networks and their composition. For different network architectures, we formulate integer linear programs which model the design task in detail. Moreover, network survivability is an important issue due to the immense bandwidths offered by optical technology. Operators therefore request for designs which perpetuate protected connections and guarantee for a defined minimum throughput in case of malfunctions. In order to achieve an effective realization of scalable protection, we present a novel survivability concept tailored to optical networks and integrate several variants into the models. Our solution approach is based on a suitable model decomposition into two subtasks which separates two individually hard subproblems and enables this way to compute cost-efficient designs with approved quality guarantee. The first subtask consists of routing the connections with corresponding dimensioning of capacities and constitutes a common core task in the area of network planning. Sophisticated methods for such problems have already been developed and are deployed by appropriate integration. The second subtask is characteristic for optical networks and seeks for a conflict-free assignment of available wavelengths to the lightpaths using a minimum number of involved wavelength converters. For this coloring-like task, we derive particular models and study methods to estimate the number of unavoidable conversions. As constructive approach, we develop heuristics and an exact branch-and-price algorithm. Finally, we carry out an extensive computational study on realistic data, provided by our industrial partners. As twofold purpose, we demonstrate the potential of our approach for computing good solutions with quality guarantee, and we exemplify its flexibility for application to network design and analysis.}, language = {en} } @misc{ZymolkaKosterWessaely, author = {Zymolka, Adrian and Koster, Arie M.C.A. and Wess{\"a}ly, Roland}, title = {Transparent optical network design with sparse wavelength conversion}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-7017}, number = {02-34}, abstract = {We consider the design of transparent optical networks from a practical perspective. Network operators aim at satisfying the communication demands at minimum cost. Such an optimization involves three interdependent planning issues: the dimensioning of the physical topology, the routing of lightpaths, and the wavelength assignment. Further topics include the reliability of the configuration and sparse wavelength conversion for efficient use of the capacities. In this paper, we investigate this extensive optical network design task. Using a flexible device-based model, we present an integer programming formulation that supports greenfield planning as well as expansion planning on top of an existing network. As solution method, we propose a suitable decomposition approach that separates the wavelength assignment from the dimensioning and routing. Our method in particular provides a lower bound on the total cost which allows to rate the solution quality. Computational experiments on realistic networks approve the solution approach to be appropriate.}, language = {en} } @misc{Zaenker, type = {Master Thesis}, author = {Z{\"a}nker, Martin}, title = {Estimating Human Face Reflectance from Single-Shot Multiview Data}, language = {en} } @phdthesis{Zoeckler, author = {Z{\"o}ckler, Maja}, title = {Modellgebundene Cranioplastie - Operationstechnik zur Umformung fr{\"u}hkindlicher Sch{\"a}deldeformit{\"a}ten unter Verwendung dreidimensionaler Standardformmodelle aus MRT-basierten Rekonstruktionen nicht deformierter Kinder}, language = {de} } @misc{Zoeckler1997, type = {Master Thesis}, author = {Z{\"o}ckler, Malte}, title = {Molekulardynamische Simulation des Wachstums zirkumstellarer Silikatstaubteilchen}, year = {1997}, language = {en} }