[1] Portuguese Naval Acad, Escola Naval, Portuguese Navy Res Ctr, CINAV, P-2810001 Almada, Portugal
[2] NOVA Sch Sci & Technol, Ctr Math & Applicat CMA, P-2829516 Caparica, Portugal
[3] Portuguese Navy Res Ctr, CINAV, P-2810001 Almada, Portugal
[4] Univ Nova Lisboa, NOVA Informat Management Sch Nova IMS, Lisbon, Portugal