Institution: | [1]Department of Applied Mathematics, EUIT de Minas y Obras P(tblicas, Universidad del Pals Vasco UPV/EHU, Colina de Beurko s/n, 48902 Barakaldo, Spain [2]Department of Applied Mathematics, ETS de Ingenieria de Bilbao, Universidad del Pals Vasco UPV/EHU, Alameda de Urquijo s/n, 48013 Bilbao, Spain |