1. Department of Mechanical Engineering and Industrial Systems; Tampere University of Technology; P.O. Box 589, FIN-33101 Tampere Finland
2. Laboratoire Roberval; Université de Compiègne; BP 20529-60205, Compiègne France
3. Faculty of Engineering; Tel Aviv University; 69978 Ramat Aviv Israel
4. Ecole Normale Supérieure de Cachan; LMT-Cachan; 61, avenue du président Wilson, 94235 Cachan France