1. PhD, Faculty of Agricultural Engineering, Technion–Israel Institute of Technology, Haifa 32000.
2. PhD, Dept. of Civil Engineering, Univ. of Cape Town, Rondebosch 7701, South Africa (corresponding author).
3. PhD, School of Physics, Univ. of the Witwaterstand, Private Bag 3, WITS 2050, Johannesburg-Gauteng, South Africa.
4. Associate Professor, RE Loewenthal, Dept. of Civil Engineering, Univ. of Cape Town, Rondebosch 7701, South Africa.