1. Department of Mathematics , University of Cape Coast, Ghana Regional Transport Research and Education Centre Kumasi, Kwame Nkrumah University of Science and Technology , Kumasi , Ghana
2. African Institute for Mathematical Sciences , Ghana; Department of Mathematics, School of Science, College of Science and Technology , University of Rwanda , Rwanda
3. African Institute for Mathematical Sciences , Ghana; IFAM, Department of Mathematical Sciences , University of Liverpool , United Kingdom
4. Department of Mathematics , Kwame Nkrumah University of Science andTechnology , Kumasi , Ghana
5. Complex Systems Research Center , Shanxi University , Taiyuan , China