1. Dep. of Biosystems Engineering; Jordan Univ. of Science and Technology; P.O. Box 3030 Irbid Jordan
2. School of Engineering, Univ. of Guelph; Guelph ON Canada N1G 2W1
3. J.F. Sabourin and Associates, Inc.; Ottawa ON Canada
4. Dep. of Environmental Biology; Univ. of Guelph; Guelph ON Canada N1G 2W1