1. University of Bremen; Dept. Math. & Comp. Science; Robert-Hooke-Str. 5 Bremen 28359 Germany
2. University of Bremen; ISIS Scientific Centre; Wiener Straße 12 Bremen 28359 Germany
3. University of Bremen; Inst Microsensors, -actuators & -systems; Otto-Hahn-Allee 1 Bremen 28359 Germany
4. University of Bremen; Director of Fraunhofer IFAM; Wiener Straße 12 Bremen 28359 Germany