C. Alemanya, C. Trassyb,*, B. Pateyronc, K.-I. Lib, Y. Delannoyb
a LPCI, bat 401, INSA, F-69621 Villeurbanne, France
b EPM-Madylam, ENSHMG, BP 95, F-38402 Saint Martin d’H" eres, France
c SPCTS, Facult!e des sciences, 123 av. A. Thomas, F-87060 Limoges, France