| Apr 14, 2011 |
Stefan Liebscher
(Freie Universität Berlin) |
Fishing for ideas on Bianchi Models |
| Apr 28, 2011 |
SFB 910,
Opening Colloquium |
| May 5, 2011 |
Johannes Buchner
(Freie Universität Berlin) |
Towards a convergence result for Bianchi cosmologies of class B |
The BKL conjecture suggests that the approach to the initial singularity
("big bang") is vacuum dominated, local and oscillatory. After some
results have been achieved in a spatially homogeneous setting of Bianchi
class A (Mixmaster-models), the natural next step is to consider Bianchi
models of class B.
In my talk, I will deal with the Bianchi VI-1/9-model - the most
important one in class B, as it is the only Bianchi model appearing in the
simplest osciallatory PDE cosmological models.
I will show that the combined local linear passage near the 3-cycle of the
Kasner-circle yields a convergence towards the conjectured
Bianchi-attractor. I will then discuss what steps are necessary to turn
this into a rigorous convergence theorem, including a detailed study of
the global passage between the local passages near the Kasner circle.
|
| May 12, 2011 |
Sergey Tikhomirov
(Freie Universität Berlin) |
Control by hysteresis in reaction-diffusion systems |
|
Hysteresis plays a crucial role in control of artificial systems and
those created by nature. In the talk, we discuss how it may lead to
periodic regimes and pattern
formation in various reaction-diffusion equations.
|
| May 19, 2011 |
Abderrahim Azouani
(Freie Universität Berlin) |
Feedback control of nonlinear dissipative systems. Reaction-diffusion paradigm |
|
The aim of this talk is to design a feedback control that stabilizes an unstable solution of a reaction-diffusion equation, as an example of dissipative evolution equations on the finite-dimensional space, by introducing an approximate interpolant of order h.
First, our result is demonstrated for the case of local averages, which is the most straightforward approach. Later, a more general abstract result will be presented that unifies our approach, utilizing all types of approximate interpolant observables and controllers. It will be shown that this abstract approach applies to the Fourier modes and nodal value as particular examples.
If we have time, I will present briefly a different feedback control based on nodal value observables and feedback controllers. The observables are the values of the solutions u(xk) while the feedback controllers are at some points xk.
Joint work with E.S. Titi (University of California, Weizmann Institute of Science).
|
| May 26, 2011 |
Pavel Gurevich
(Freie Universität Berlin) |
Reaction-diffusion equations with spatially distributed hysteresis |
|
We consider reaction-diffusion equations involving a hysteretic discontinuity which is defined at each spatial point. We call this discontinuity spatially distributed hysteresis. In the talk, we discuss how it naturally appears and which basic properties it possesses. We give a sufficient condition under which the problem is well posed and formulate open questions for further research.
|
Tuesday
May 31, 2011 |
Juliette Hell
(Freie Universität Berlin) |
Dynamics at Infinity |
| June 9, 2011 |
Isabelle Schneider
(Free University Berlin) |
Delay stabilization of periodic orbits in coupled oscillator systems |
Anna Karnauhova
(Free University Berlin) |
On manifolds admitting Anosov diffeomorphisms |
Christopher Brandt
(Free University Berlin) |
Problems in the proof of the existence of a cascade of period doubling bifurcations |
| June 16, 2011 |
Sergey Skopinov
(Saint-Petersburg State University) |
Microwave heating |
Bernold Fiedler
(Free University Berlin) |
Flageolet on the vibrating string: theory and experiments |
Flageolet is a very common playing technique on string instruments: the finger touches the
string slightly, at integer partitions, to produce a peculiar whistling-like sound.
The standard string equation, alias the linear wave equation on the interval, does not
accommodate such an effect. I discuss several generalizations, based on
qualitative and quantitative experiments on my violin during the talk.
Thanks are due to Stefan Liebscher, for helpful hints on friction, and to Wolfgang Boettcher, for helpful demonstrations on his cello.
|
| June 23, 2011 |
Sergey Skopinov
(Saint-Petersburg State University) |
Boundedness and unboundedness of classical solutions in one-dimensional heating problems |
| June 30, 2011 |
Waldyr Muniz Oliva
(Instituto Superior Tecnico, Lisbon, Portugal) |
The story of the Lotka-Volterra systems |
1. Basic notions on conservative, dissipative and stably dissipative
L-V systems.
2. Associated graphs and the Volterra's characterization of conservative
systems. Symplectic and Poisson structures, Volterra's direct hamiltonian
formulation with the double of variables and the reduction.
3. Stably dissipative L-V systems and the hamiltonian dynamics of the
attractor. The reduction of that dynamics to another L-V system with
less dimensions.
4. Recent results.
|
Friday
July 1, 2011 |
Discussion |
Recent results on Lotka-Volterra systems |
| July 7, 2011 |
BCSCCS conference: Engineering of Chemical Complexity |
| July 14, 2011 |
Anna Karnauhova | On Manifolds Admitting Anosov Diffeomorphisms |
| Vu Xuan Tuyen | The global attractor of the sunflower equation |
| Konstantin Bubulz | Possibilities of delay stabilization in coupled oscillator systems |
| Christopher Brandt | State of my bachelor thesis on homoclinic bifurcations |
| Isabelle Schneider | Delay stabilization of periodic orbits in coupled oscillator systems |
| Matthias Bosewitz | Delay stabilization of periodic orbits in systems with two coupled oscillators |
Last change: Jul. 14, 2011
