1. Department of Civil and Environmental Engineering, Politecnico di Milano, 20133 Milan, Italy.
2. Université de Lorraine, CNRS, IECL, Inria, F-54000 Nancy, France.
3. Inria - 2 rue Simone Iff, 75589, Paris, France and Université Paris-Est, CERMICS (ENPC), 6 et 8 av. Blaise Pascal, 77455, Marne-la-Vallée Cedex 2, France.