1. Department of Mechanics, Mechatronics Laboratory, Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino, Italy
2. Mechatronics Laboratory, Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino, Italy
3. Whole Engine Modeling Department, Rolls-Royce Plc., P.O. Box 31, Derby DE24 8BJ, England