Refine
Year of publication
- 1997 (453) (remove)
Document Type
- Article (348)
- Monograph/Edited Volume (63)
- Preprint (25)
- Doctoral Thesis (11)
- Review (5)
- Other (1)
Language
- English (453) (remove)
Keywords
- manifolds with singularities (3)
- pseudodifferential operators (3)
- Fredholm property (2)
- Mellin transform (2)
- conical singularities (2)
- elliptic operators (2)
- index (2)
- 'eta' invariant (1)
- APS problem (1)
- Atiyah-Bott condition (1)
Institute
- Institut für Physik und Astronomie (125)
- Institut für Mathematik (93)
- Institut für Biochemie und Biologie (55)
- Institut für Chemie (39)
- Wirtschaftswissenschaften (27)
- Institut für Geowissenschaften (25)
- Institut für Informatik und Computational Science (23)
- Department Psychologie (12)
- Institut für Anglistik und Amerikanistik (11)
- Interdisziplinäres Zentrum für Dünne Organische und Biochemische Schichten (10)
- Interdisziplinäres Zentrum für Dynamik komplexer Systeme (8)
- Historisches Institut (6)
- Institut für Ernährungswissenschaft (5)
- Sozialwissenschaften (5)
- Department Linguistik (4)
- Philosophische Fakultät (4)
- Institut für Germanistik (2)
- Institut für Romanistik (2)
- Institut für Umweltwissenschaften und Geographie (2)
- Department Erziehungswissenschaft (1)
- Department Sport- und Gesundheitswissenschaften (1)
- Institut für Jüdische Studien und Religionswissenschaft (1)
- Interdisziplinäres Zentrum für Biopolymere (1)
- Lehreinheit für Wirtschafts-Arbeit-Technik (1)
- Strafrecht (1)
- Zentrum für Gerechtigkeitsforschung (1)
- Öffentliches Recht (1)
We develop a method of finding analytical sotutions of the Bogolyubov-de Gennes equations for the excitations of a Bose condensate in the Thomas-Fermi regime in harmonic traps of any asymmetry and introduce a classification of eigenstates. In the case of cylindrical symmetry we emphasize the presence of an accidental degeneracy in the excitation spectrum at certain values of the projection of orbital angular momentum on the symmetry axis and discuss possible consequences of the degeneracy in the context of new signatures of Bose- Einstein condensation
Two-dimensional bouyancy-driven convection in a horizontal fluid layer with stress-free boundary conditions at top and bottom and periodic boundary conditions in the horizontal direction is investigated by means of numerical simulation and bifurcation-analysis techniques. As the bouyancy forces increase, the primary stationary and symmetric convection rolls undergo successive Hopf bifurcations, bifurcations to traveling waves, and phase lockings. We pay attention to symmetry breaking and its connection with the generation of large-scale horizontal flows. Calculations of Lyapunov exponents indicate that at a Rayleigh number of 2.3×105 no temporal chaos is reached yet, but the system moves nonchaotically on a 4-torus in phase space.
Control of noise-induced oscillations of a pendulum with a rondomly vibrating suspension axis
(1997)
The pendant drop technique was used to determine p/A isotherms of docosanic acid spread on the drop surface of an aqueous polymer solution. Two water soluble polymers were used, poly(dimethyl-diallyl-ammoniumchloride) and sodium poly(styrene sulfonate-b-ethylethylene). By fast changes of the drop volume, the monolayers were compressed and dilated. The stress relaxation was monitored and surface rheological dilation parameters were obtained. It is shown that the fatty acid monolayer can be mechanically stabilized by both interacting anionic and cationic polymers. In the case of the anionic polymer, the interaction becomes more pronounced in the presence of salts in the subphase (counterions). Brewster angle microscopy shows that the typical tilt-orientation of crystalline domains of the fatty acid monolayers transforms into a more uniform and fluid-like structure caused by the polymer/monolayer interaction. The surface rheological behavior is dramatically influenced by the polymer binding. The interaction results in surface dilational viscoelastic properties and show that there is a strong resistance against expansion of the complex fatty acid/polymer layer.
The dynamics of noisy bistable systems is analyzed by means of Lyapunov exponents and measures of complexity. We consider both the classical Kramers problem with additive white noise and the case when the barrier fluctuates due to additional external colored noise. In case of additive noise we calculate the Lyapunov exponents and all measures of complexity analytically as functions of the noise intensity resp. the mean escape time. For the problem of fluctuating barrier the usual description of the dynamics with the mean escape time is not sufficient. The application of the concept of measures of complexity allows to describe the structures of motion in more detail. Most complexity measures sign the value of correlation time at which the phenomenon of resonant activation occurs with an extremum.