1. a School of Electronic and Electrical Engineering , The University of Birmingham , P.O. Box 363, Birmingham, England, B15 2TT, U.K.
2. b Department of Chemical and Process Engineering , The National University of Malaysia , Bangi, Selangor, 43600, Malaysia.
3. c Department of Electrical, Electronic and Information Engineering , Control Engineering Centre, City University , Northampton Square, London, EC1V 0HB, England, U.K.