1. Faculty of Agriculture and Environment, University of Sydney, NSW 2006, Australia.
2. Kulliyyah of Science, International Islamic University of Malaysia, Kuantan, Pahang, Malaysia.
3. Department of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006, Australia.
4. Corresponding author. Phone: +61 2 8627 1017. Fax: +61 2 8627 1099. E-mail: les.copeland@sydney.edu.au