1. School of Physics; Universiti Sains Malaysia; 11800 USM Penang Malaysia
2. Faculty of Electronic and Computer Engineering; Universiti Teknikal Malaysia Melaka; Hang Tuah Jaya 76100 Durian Tunggal Melaka Malaysia
3. School of Engineering; Newcastle University; Newcastle Upon Tyne NE1 7RU United Kingdom
4. School of Natural Environmental Sciences; Newcastle University; Newcastle Upon Tyne NE1 7RU United Kingdom
5. Department of Engineering; University of Durham; Durham DH1 3LE United Kingdom