1. Department of Mechanics, Faculty of Civil Engineering; Czech Technical University in Prague; Thákurova 7, 166 29 Prague 6 Czech Republic
2. Department of Mechanical Engineering; Eindhoven University of Technology; P.O. Box 513, 5600 MB Eindhoven The Netherlands
3. Faculté des Sciences, de la Technologie et de la Communication, Campus Kirchberg; Université du Luxembourg; 6 rue Richard Coudenhove-Kalergi, L-1359 Luxembourg