[1] Queen Mary Univ London, Sch Phys & Astron, London E1 4NS, England
[2] Queen Mary Univ London, Sch Engn & Mat Sci, London E1 4NS, England
[3] Univ Ioannina, Dept Mat Sci & Engn, GR-45110 Ioannina, Greece
[4] Hellen Mediterranean Univ, Dept Mech Engn, Iraklion 71004, Greece