1. Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455
2. GRESPI, University of Reims, Campus du Moulin de la Housse - BP 1039, 51687 Reims Cedex 2, Reims, France
3. Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455 e-mail :