1. Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
2. Institute of Thermomechanics of the Czech Academy of Sciences, Dolejskova 5, CZ-182 00 Prague 8, Czech Republic
3. Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands