K. M. A. Saron - Al Jouf University
M. Ibrahim - Physics Department, College of Science and Arts, Jouf University, P.O. Box 756, Al-Gurayyat, Saudi Arabia
M. R. Hashim - Universiti Sains Malaysia
T. A. Taha - Al Jouf University
Nezar G. Elfadill - National Energy Research Center—Solar Energy Institute, P.O. Box 4032 Khartoum, Sudan
E. M. Mkawi - King Abdulaziz University
Nageh K. Allam - American University in Cairo