1. Fellow ASME Department of Ocean and Mechanical Engineering, Florida Atlantic University, Boca Raton, FL 33431-0991 e-mail:
2. School of Computing and Mathematics, Keele University, Keele, Staffordshire ST5 5BG, UK e-mail:
3. Department of Mathematics, Brunel University, Uxbridge, Middlesex UB8 3PH, UK e-mail: