1. Electronics and Telecommunications Department, Scientific Research and Advanced Studies of Ensenada (CICESE), Km. 107, Carretera Tijuana-Ensenada, Ensenada, B.C., 22860, Mexico
2. Faculty of Mathematical Sciences, C. J. Drebbel-Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
3. Faculty of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands