- Dr Mohsin Hasan Abd ALLAH Hashim, Dean of Faculty of Mathematical Sciences, Univer- sity of Khartoum, Khartoum, Sudan. Tel: +249183774443. Fax: +249183780295. Email: mhashim@uofk.edu , mhashim@yahoo.com.
- Dr Altayeb Abdel Rahman, Head of Applied Mathematics Department, Faculty of Mathe- matical Sciences, University of Khartoum, Khartoum, Sudan. Tel: +249183774443. Fax: +249183780295. Email: a.abdelrahman@uofk.com.
- Mr Suliman Mohammed Abdel Kareem, Manager of Gard Solution Company. Email: sma kareem@yahoo.com .