TY - BOOK A1 - Braun, Robert A1 - Feudel, Fred A1 - Guzdar, P. T1 - The route to chaos for a two-dimensional externally driven flow : [to appear in Physical Review E] T3 - Preprint NLD Y1 - 1998 SN - 1432-2935 VL - 46 PB - Univ. Potsdam CY - Potsdam ER - TY - BOOK A1 - Braun, Robert A1 - Feudel, Fred A1 - Seehafer, Norbert T1 - Bifurcations and chaos in an array of forced vortices T3 - Preprint NLD Y1 - 1997 SN - 1432-2935 VL - 37 PB - Univ. Potsdam CY - Potsdam ER - TY - BOOK A1 - Böckmann, Christine T1 - Retrieval of multimodal aerosol size distribution by inversion of multiwavelength data T3 - Preprint NLD Y1 - 1997 SN - 1432-2935 VL - 38 PB - Univ. Potsdam CY - Potsdam ER - TY - BOOK A1 - Cramer, Marcus A1 - Eisert, Jens A1 - Illuminati, Fabrizio T1 - Inhomogeneous atomic Bose-Fermi mixtures in cubic lattices N2 - We determine the ground state properties of inhomogeneous mixtures of bosons and fermions in cubic lattices and parabolic confining potentials. For finite hopping we determine the domain boundaries between Mott-insulator plateaux and hopping-dominated regions for lattices of arbitrary dimension within mean-field and perturbation theory. The results are compared with a new numerical method that is based on a Gutzwiller variational approach for the bosons and an exact treatment for the fermions. The findings can be applied as a guideline for future experiments with trapped atomic Bose- Fermi mixtures in optical lattices Y1 - 2004 SN - 0031-9007 ER - TY - BOOK A1 - Donner, Reik Volker A1 - Cser, Adrienn A1 - Schwarz, Udo A1 - Otto, Andreas H. A1 - Feudel, Ulrike T1 - An approach to a process model of laser beam melt ablation using methods of linear and non-linear data analysis N2 - As a non-contact process laser beam melt ablation offers several advantages compared to conventional processing mechanisms. During ablation the surface of the workpiece is molten by the energy of a CO2-laser beam, this melt is then driven out by the impulse of an additional process gas. Although the idea behind laser beam melt ablation is rather simple, the process itself has a major limitation in practical applications: with increasing ablation rate surface quality of the workpiece processed declines rapidly. With different ablation rates different surface structures can be distinguished, which can be characterised by suitable surface parameters. The corresponding regimes of pattern formation are found in linear and non-linear statistical properties of the recorded process emissions as well. While the ablation rate can be represented in terms of the line-energy, this parameter does not provide sufficient information about the full behaviour of the system. The dynamics of the system is dominated by oscillations due to the laser cycle but includes some periodically driven non-linear processes as well. Upon the basis of the measured time series, a corresponding model is developed. The deeper understanding of the process can be used to develop strategies for a process control. Y1 - 2004 SN - 3-527-40430-9 ER - TY - BOOK A1 - Donner, Reik Volker A1 - Cser, Adrienn A1 - Schwarz, Udo A1 - Otto, Andreas H. A1 - Feudel, Ulrike T1 - An approach to a process model of laser beam melt ablation using methods of linear and non-linear data analysis N2 - As a non-contact process laser beam melt ablation offers several advantages compared to conventional processing mechanisms. During ablation the surface of the workpiece is molten by the energy of a CO2-laser beam, this melt is then driven out by the impulse of an additional process gas. Although the idea behind laser beam melt ablation is rather simple, the process itself has a major limitation in practical applications: with increasing ablation rate surface quality of the workpiece processed declines rapidly. With different ablation rates different surface structures can be distinguished, which can be characterised by suitable surface parameters. The corresponding regimes of pattern formation are found in linear and non-linear statistical properties of the recorded process emissions as well. While the ablation rate can be represented in terms of the line-energy, this parameter does not provide sufficient information about the full behaviour of the system. The dynamics of the system is dominated by oscillations due to the laser cycle but includes some periodically driven non-linear processes as well. Upon the basis of the measured time series, a corresponding model is developed. The deeper understanding of the process can be used to develop strategies for a process control. Y1 - 2003 SN - 3-928921-88-6 ER - TY - BOOK A1 - Engbert, Ralf T1 - Tempo-induced transitions in polyrhythmic hand movements T3 - Preprint NLD Y1 - 1997 SN - 1432-2935 VL - 41 PB - Univ. Potsdam CY - Potsdam ER - TY - BOOK A1 - Feldmeier, Achim T1 - Theoretical Fluid Dynamics T3 - Theoretical and Mathematical Physics Y1 - 2019 SN - 978-3-030-31021-9 (online) SN - 978-3-030-31023-3 (print) U6 - https://doi.org/10.1007/978-3-030-31022-6 PB - Springer CY - Cham ER - TY - BOOK A1 - Freude, Ulrike A1 - Kuznetsov, Sergey P. A1 - Pikovskij, Arkadij T1 - Strange nonchaotic attractors : dynamics between order and chaos in Quasiperiodically Forced Systems Y1 - 2006 SN - 981-256633-3 PB - World Scientific CY - Singapore ER - TY - BOOK A1 - Gutlederer, Erwin Johann T1 - On the morphology of vesicles. - [überarb. Diss.] N2 - This dissertation contains theoretical investigations on the morphology and statistical mechanics of vesicles. The shapes of homogeneous fluid vesicles and inhomogeneous vesicles with fluid and solid membrane domains are calculated. The influence of thermal fluctuations is investigated. The obtained results are valid on mesoscopic length scales and are based on a geometrical membrane model, where the vesicle membrane is described as either a static or a thermal fluctuating surface. The thesis consists of three parts. In the first part, homogeneous vesicles are considered. The focus in this part is on the thermally induced morphological transition between vesicles with prolate and oblate shape. With the help of Monte Carlo simulations, the free energy profile of these vesicles is determined. It can be shown that the shape transformation between prolate and oblate vesicles proceeds continuously and is not hampered by a free energy barrier. The second and third part deal with inhomogeneous vesicles which contain intramembrane domains. These investigations are motivated by experimental results on domain formation in single or multicomponent vesicles, where phase separation occurs and different membrane phases coexist. The resulting domains differ with regard to their membrane structure (solid, fluid). The membrane structure has a distinct effect on the form of the domain and the morphology of the vesicle. In the second part, vesicles with coexisting solid and fluid membrane domains are studied, while the third part addresses vesicles with coexisting fluid domains. The equilibrium morphology of vesicles with simple and complex domain forms, derived through minimisation of the membrane energy, is determined as a function of material parameters. The results are summarised in morphology diagrams. These diagrams show previously unknown morphological transitions between vesicles with different domain shapes. The impact of thermal fluctuations on the vesicle and the form of the domains is investigated by means of Monte Carlo simulations. N2 - Die vorliegende Arbeit enthält theoretische Untersuchungen zur Morphologie und statistischen Mechanik von Vesikeln. Es wird die Gestalt homogener fluider Vesikel und inhomogener Vesikel mit fluiden und festen Membrandomänen berechnet. Der Einfluss thermischer Fluktuationen wird untersucht. Die erzielten Ergebnisse beziehen sich auf mesoskopische Längenskalen und basieren auf einem geometrischen Membranmodell, in welchem die Vesikelmembran als statische, beziehungsweise thermisch fluktuierende Fläche beschrieben wird. Die Arbeit besteht aus drei Teilen. Im ersten Teil werden homogene fluide Vesikel betrachtet. Das Interesse gilt dem thermisch induzierten Morphologieübergang zwischen prolaten und oblaten Vesikelformen. Mit Hilfe von Monte-Carlo-Simulationen wird ein freies Energieprofil für diese Vesikel ermittelt. Es kann gezeigt werden, dass die Formumwandlung zwischen prolaten und oblaten Formen kontinuierlich verläuft und mit keiner freien Energiebarriere verbunden ist. Der zweite und dritte Teil beschäftigt sich mit inhomogenen Vesikeln, die intramembrane Domänen enthalten. Ausgangspunkt und Motivation der Berechnungen sind experimentelle Studien über Domänbildung in ein- oder mehrkomponentigen Vesikelmembranen, bei denen Phasentrennung stattfindet und unterschiedliche Membranphasen koexistieren. Die dabei auftretenden Domänen unterscheiden sich hinsichtlich ihrer Membranstruktur (fest, fluid). Diese beeinflusst die Form der Domäne und des gesamten Vesikels auf entscheidende Weise. Im zweiten Teil werden Vesikel untersucht, bei denen feste und fluide Membrandomänen koexistieren, Teil drei widmet sich Vesikeln mit zwei koexistierenden fluiden Membranphasen. In Abhängigkeit von Materialparametern werden durch Minimierung der Membranenergie die Grundzustandsformen von Vesikeln mit einfachen und komplexen Domänenformen bestimmt. Die Ergebnisse werden in Morphologiediagrammen zusammengefasst. Dabei werden bisher unbekannte Morphologieübergänge zwischen Vesikeln mit unterschiedlichen Domänformen beobachtet. Die Auswirkungen thermischer Fluktuationen auf die Vesikel und die Form ihrer Domänen werden mittels Monte-Carlo-Simulationen untersucht. KW - Vesikel KW - Membran KW - Domänen KW - vesicle KW - membrane KW - domains Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15065 ER -