On the Floquet Theory of Delay Differential Equations

We present an analytical approach to deal with nonlinear delay differential equations close to instabilities of time periodic reference states. To this end we start with approximately determining such reference states by extending the Poincar'e Lindstedt and the Shohat expansions which were originally developed for ordinary differential equations. Then we systematically elaborate a linear stability analysis around a time periodic reference state. This allows to approximately calculate the Floquet eigenvalues and their corresponding eigensolutions by using matrix valued continued fractions

On the Mechanism of Time--Delayed Feedback Control

The Pyragas method for controlling chaos is investigated in detail from the experimental as well as theoretical point of view. We show by an analytical stability analysis that the revolution around an unstable periodic orbit governs the success of the control scheme. Our predictions concerning the transient behaviour of the control signal are confirmed by numerical simulations and an electronic circuit experiment.Comment: 4 pages, REVTeX, 4 eps-figures included Phys. Rev. Lett., in press also available at http://athene.fkp.physik.th-darmstadt.de/public/wolfram.htm

Time--delay autosynchronization of the spatio-temporal dynamics in resonant tunneling diodes

The double barrier resonant tunneling diode exhibits complex spatio-temporal patterns including low-dimensional chaos when operated in an active external circuit. We demonstrate how autosynchronization by time--delayed feedback control can be used to select and stabilize specific current density patterns in a noninvasive way. We compare the efficiency of different control schemes involving feedback in either local spatial or global degrees of freedom. The numerically obtained Floquet exponents are explained by analytical results from linear stability analysis.Comment: 10 pages, 16 figure

Microsystem Technology for Ambient Assisted Living (AAL)

AbstractAAL is certainly an application area with sensor as well as actuator needs. Some of the requirements can be fulfilled by state of the art technology; some areas however still need a lot of R&D efforts for potential applications in homes. The contribution describes two areas of interest and actual development: One is the topic of robust fire detection; the other domain is fall detection. For both application areas one has to understand both the state of the art and the drawbacks of the current solutions. One can state clearly that there is a huge potential for the development of new microsystems. Still one has to keep in mind that usage in elderly homes also requires consent and cooperation of the users which is the focus of the user centered design principle

License management in grid and cloud computing

The lack of license management schemes in distributed environments is becoming a major obstacle for the commercial adoption of Grid or Cloud infrastructures. In this paper, we present a complete license management architecture that enables a pay-per-use license management which can be deployed together with an on-demand computing scenario. Our architecture enables authenticated access to a remote license server. The license management architecture can be deployed in any distributed environment. It supports existing client/server based software license management tools (for example FlexNet Publisher). This allows an easy transition from current software license business models which support only a local license management towards business models which support license management in distributed environments

On-demand software licence provisioning in grid and cloud computing

The lack of licence management schemes in distributed environments is becoming a major obstacle for the commercial adoption of grid or cloud infrastructures. In this paper, we present a complete licence management architecture that enables a pay-per-use licence management, which can be deployed together with an on-demand computing scenario. Our architecture enables authenticated access to a remote licence server. The licence management architecture can be deployed in any distributed environment. It supports existing client/serverbased software licence management tools (e.g. FlexNet Publisher). This allows an easy transition from current software licence business models, which support only a local licence management towards business models that support licence management in distributed environments