1. a School of Material and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Seberang Perai Selatan, Pulau Pinang, Malaysia
2. b School of Material and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Seberang Perai Selatan, Pulau Pinang, Malaysia
3. c School of Material and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Seberang Perai Selatan, Pulau Pinang, Malaysia