Thesis Supervisor Certified by

2012

I, the undersigned, hereby declare that the content of this dissertation is my own original work and that I have not previously submitted it to any other university for a degree, either in part or in its entirety.

This work has not been presented elsewhere for the award of a degree, or any other purpose. Candidate's Name: Falade, Adesegun Ibrahim (MAT. NO: PMT/09/9099) Signature………………………………………………………. Date………………………. (b) (By the Supervisor) I certify that this work was carried out by Mr. Falade, Adesegun Ibrahim (MAT. NO: PMT/09/9099) in the department

2000

This is to certify that I have examined this copy of master's thesis by

2013

i TABLE OF CONTENTS Abstract..................................................................................................................................v

2005

I hereby declare that this dissertation, prepared for the degree Philosophiae Doctor, which was submitted by me to the University of the Free State, is my original work and has not previously in its entirety or in part been submitted to any other University. All sources of materials and financial assistance used for study have been duly acknowledged. I also agree that the University of the Free State has the sole right to the publication of this dissertation. Signed on ___________________ _ November 2005 at the University of Free State,

2018

2015

ii DECLARATION This Research project is my original work and has not been presented for a degree in any other University

Advisor signature ____________________ ___________________________ Examiner Signature ____________________ ___________________________ Examiner Signature ACKNOWLEDGEMENT First of all, I am greatly indebted to my almighty God for helping me complete this research work and for all his help throughout my life. I am grateful to my advisor, Mebratu Mulatu (Dr.), who critically read through the draft copies and gave me valuable suggestions and constructive comments. Without his sincere and dedicated guidance, this thesis would not have taken its present form. My heartfelt thanks and indebtedness go to my Co-advisor, Kebede Micaheal (Dr.), for his continued support during this study. He is more than what I say. Had He not helped me from the very start of my research, I could not have reached this level.

Declare that: 1. This thesis has never been submitted to any other tertiary education institution for any other academic degree. 2. This thesis is the sole work of the author and has not been written in collaboration with any other person, nor does it include, without due acknowledgement, the work of any other person. 3. Should it later be found that this thesis is product of plagiarism, I am willing to accept any legal consequences that may be imposed to me. Malang,