1. Ph.D. Scholar, School of Engineering, Faculty of Science, Agriculture and Engineering, Newcastle Univ., Newcastle upon Tyne NE1 7RU, UK.
2. Senior Lecturer, School of Engineering, Faculty of Science, Agriculture and Engineering, Newcastle Univ., Newcastle upon Tyne NE1 7RU, UK.
3. Lecturer, School of Engineering, Faculty of Science, Agriculture and Engineering, Newcastle Univ., Newcastle upon Tyne NE1 7RU, UK (corresponding author).