1. Department of Industrial and Information Engineering and Economics, University of L’Aquila and UdR INSTM of L’Aquila, Via G. Gronchi 18, I-67100 L’Aquila, Italy
2. Department of Physical and Chemical Sciences, University of L’Aquila, via Vetoio, 67100 L’Aquila (AQ), Italy
3. Department of Civil & Environmental Engineering (DICA), Università degli Studi di Perugia, Via G. Duranti 93, 06125 Perugia, Italy
4. CNR-SCITEC, 06123 Perugia, Italy