Structure and stylized facts of a deregulated power market

Computer Methods in Applied Mechanics and Engineering, 2003

Acta Mathematica Hungarica, 2000

Journal of Computer Science and Technology, 2007

Workshop on the …, 2002

Theoretical Computer Science, 2003

Acta Informatica, 2004

We propose an extension to the formalism of timed automata by allowing urgent transitions. An urgent transition is a transition which must be taken within a fixed time interval from its enabling time and it has higher priority than other non-urgent transitions enabled in the same state. We give a set of rules formally describing the behavior of urgent transitions and we show that, from a language theoretic point of view, the addition of urgency does not improve the expressive power of timed automata. From a specification point of view, the use of urgent transitions allows shorter and clear specifications of behaviors involving urgency and priority. We use timed automata with urgent transitions for specifying a multicast protocol for mobile computing.

Journal of Business & Economic Statistics, 2004

IEEE Signal Processing Magazine, 2002

2004

Clusters of correlated activity in fMRI data can identify regions of interest and indicate interacting brain areas. Because the extraction of clusters is computationally complex, we apply an approximative method which is based on Hopfield networks. It allows to find clusters of various degrees of connectivity ranging between the two extreme cases of cliques and connectivity components. Further we propose a criterion which allows to evaluate the relevance of such structures based on the robustness with respect to parameter variations.