1. Max Planck Institute for Intelligent Systems Heisenbergstr. 3 Stuttgart 70569 Germany
2. State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing Jiangsu 210016 China
3. Institute of Dynamics and Vibration Research Leibniz Universität Hannover An der Universität 1 Garbsen 30823 Germany
4. Institute of Physical Chemistry University of Stuttgart Pfaffenwaldring 55 Stuttgart 70569 Germany