[1] Univ Plymouth, Sch Engn Comp & Math, Plymouth PL4 8AA, England
[2] Univ Roma Tor Vergata, Dept Civil Engn & Comp Sci, Via Politecn 1, I-00133 Rome, Italy
[3] Zhejiang Univ, Ocean Coll, Zhoushan 316021, Zhejiang, Peoples R China
[4] Northumbria Univ, Dept Math Phys & Elect Engn, Math Complex & Nonlinear Phenomena MCNP, Newcastle Upon Tyne NE1 8ST, England