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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Integral Equation Methods for Rough Surface Scattering Problems in three Dimensions / Integralgleichungsmethoden für Streuprobleme an rauhen Oberflächen in drei Dimensionen

Heinemeyer, Eric 10 January 2008 (has links)
No description available.
12

Pattern Formation in Cellular Automaton Models - Characterisation, Examples and Analysis / Musterbildung in Zellulären Automaten Modellen - Charakterisierung, Beispiele und Analyse

Dormann, Sabine 26 October 2000 (has links)
Cellular automata (CA) are fully discrete dynamical systems. Space is represented by a regular lattice while time proceeds in finite steps. Each cell of the lattice is assigned a state, chosen from a finite set of "values". The states of the cells are updated synchronously according to a local interaction rule, whereby each cell obeys the same rule. Formal definitions of deterministic, probabilistic and lattice-gas CA are presented. With the so-called mean-field approximation any CA model can be transformed into a deterministic model with continuous state space. CA rules, which characterise movement, single-component growth and many-component interactions are designed and explored. It is demonstrated that lattice-gas CA offer a suitable tool for modelling such processes and for analysing them by means of the corresponding mean-field approximation. In particular two types of many-component interactions in lattice-gas CA models are introduced and studied. The first CA captures in abstract form the essential ideas of activator-inhibitor interactions of biological systems. Despite of the automaton´s simplicity, self-organised formation of stationary spatial patterns emerging from a randomly perturbed uniform state is observed (Turing pattern). In the second CA, rules are designed to mimick the dynamics of excitable systems. Spatial patterns produced by this automaton are the self-organised formation of spiral waves and target patterns. Properties of both pattern formation processes can be well captured by a linear stability analysis of the corresponding nonlinear mean-field (Boltzmann) equations.
13

Time Series Analysis informed by Dynamical Systems Theory

Schumacher, Johannes 11 June 2015 (has links)
This thesis investigates time series analysis tools for prediction, as well as detection and characterization of dependencies, informed by dynamical systems theory. Emphasis is placed on the role of delays with respect to information processing in dynamical systems, as well as with respect to their effect in causal interactions between systems. The three main features that characterize this work are, first, the assumption that time series are measurements of complex deterministic systems. As a result, functional mappings for statistical models in all methods are justified by concepts from dynamical systems theory. To bridge the gap between dynamical systems theory and data, differential topology is employed in the analysis. Second, the Bayesian paradigm of statistical inference is used to formalize uncertainty by means of a consistent theoretical apparatus with axiomatic foundation. Third, the statistical models are strongly informed by modern nonlinear concepts from machine learning and nonparametric modeling approaches, such as Gaussian process theory. Consequently, unbiased approximations of the functional mappings implied by the prior system level analysis can be achieved. Applications are considered foremost with respect to computational neuroscience but extend to generic time series measurements.
14

Preconditioned Newton methods for ill-posed problems / Vorkonditionierte Newton-Verfahren für schlecht gestellte Probleme

Langer, Stefan 21 June 2007 (has links)
No description available.
15

A Biased Urn Model for Taxonomic Identification / Ein gewichtetes Urnenmodell zur taxonomischen Identifikation

Surovcik, Katharina 26 June 2008 (has links)
No description available.
16

A Hybrid Method for Inverse Obstacle Scattering Problems / Ein hybride Verfahren für inverse Streuprobleme

Picado de Carvalho Serranho, Pedro Miguel 02 March 2007 (has links)
No description available.
17

Theory and Numerics for Shape Optimization in Superconductivity / Theorie und Numerik für ein Formoptimierungsproblem aus der Supraleitung

Heese, Harald 21 July 2006 (has links)
No description available.
18

Ein semiparametrisches Verfahren zur Planung und Auswertung von Nichtunterlegenheitsstudien im Cox-Modell / A semiparametric method for planning and evaluating non-inferiority trials in the Cox model framework

Kombrink, Karola 10 November 2011 (has links)
No description available.
19

Point Source Approximation Methods in Inverse Obstacle Reconstruction Problems / Point Source Approximation Methods in Inverse Obstacle Reconstruction Problems

Erhard, Klaus 07 November 2005 (has links)
No description available.
20

The condition number of Vandermonde matrices and its application to the stability analysis of a subspace method / Die Konditionzahl von Vandermondematrizen und ihre Anwendung für die Stabilitätsanalyse einer Unterraummethode

Nagel, Dominik 19 March 2021 (has links)
This thesis consists of two main parts. First of all, the condition number of rectangular Vandermonde matrices with nodes on the complex unit circle is studied. The first time quantitative bounds for the extreme singular values are proven in the multivariate setting and when nodes of the Vandermonde matrix form clusters. In the second part, an optimized presentation of the deterministic stability analysis of the subspace method ESPRIT is given and results from the first part are applied.

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