Affiliation: | 1. Seagate Technology , 1 Disc Drive, Springtown, Derry , BT48 0BF , Northern Ireland Adrian.B.Johnston@Seagate.com;3. Intelligent Systems Engineering Laboratory, School of Computing and Intelligent Systems, Faculty of Engineering , University of Ulster , Magee Campus, Northland Road, Derry , BT48 7JL , Northern Ireland |