1. Department of Computer Science, University of Freiburg, Freiburg im Breisgau, Germany
2. Department of Microsystems Engineering, University of Freiburg, Freiburg im Breisgau, Germany
3. Fraunhofer Institute for High-Speed Dynamics, Efringen-Kirchen, Germany
4. Department of Electrical Engineering, City University of Hong Kong, Hong Kong, China