1. School of Computer Science, Engineering and Mathematics, Flinders Univ., G.P.O. Box 2100, SA 5001, AT, e-mail: hongyu.qin@Flinders.edu.au
2. School of Civil, Mining and Environmental Engineering, Univ. of Wollongong, NSW 2522, AT (Corresponding author), e-mail: wdguo@uow.edu.au