Submitted on: 26 December 2012.
Revised on: 21 January 2013.
Accepted on: 20 February 2013.
___________________International Journal of Engineering Research in Africa
Submitted on: 14 February 2002.
Revised on: 20 March 2002.
Accepted on: 13 April 2002.
___________________International Journal of Engineering Research in Africa
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Submitted on: 12 August 2020.
Revised on: 11 November 2020.
Accepted on: 20 December 2020.
___________________International Journal of Engineering Research in Africa
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Submitted on: 20 September 2009.
Revised on: 08 November 2009.
Accepted on: 18 December 2009.
___________________International Journal of Engineering Research in Africa
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