1. FORAC, Department of Mechanical Engineering, Pavillon Adrien-Pouliot, Université Laval, Québec, G1K 7P4, Canada.
2. CIRRELT, Department of Mathematics and Industrial Engineering, École Polytechnique de Montréal, C.P. 6079, succ. Centre-ville, Montréal, H3C 3A7, Canada.