Acknowledgement
This work is supported by the Faculty of Engineering, University of
Malaya. MOSTI (Ministry of Science, Technology and Innovation,
Malaysia) is acknowledged for funding the project under FRGS (Fundamental
Research Grant Scheme, project no.: FP066/2010B). This work
is also financially supported by the University of Malaya under UMRG
grant (University of Malaya Research Grant, grant no. RP002A-13AET).