First Author:   Bala Dahiru Abdullahi Department of Economic Engineering, Kyushu University, Fukuoka, Japan. audubm@yahoo.co.uk   301 River Crest 21, 11-57, Matsushima-2 Chome,, Higashi-ku Fukuoka, 812-0062, JAPAN   08049387772(Phone) 08049387772(Fax)