Dr. Md. Habibur Rahman Professor Department of Mathematics Khulna University of Engineering & Technology (KUET) Khulna -9203, Bangladesh. Phone: +880-41-769471~5, Ext-581 Cell: +8801718026012, +8801302797050, Fax: +88041774403, Mail : [email protected], [email protected] Website : www.kuet.ac.bd/math/hrahman/