1. Ph.D. Student, Fibre and Particle Engineering, Faculty of Technology, Univ. of Oulu, P.O. Box 4300, Oulu 90014, Finland.
2. Senior Research Fellow, Fibre and Particle Engineering, Faculty of Technology, Univ. of Oulu, P.O. Box 4300, Oulu 90014, Finland (corresponding author).
3. Senior Research Fellow, Fibre and Particle Engineering, Faculty of Technology, Univ. of Oulu, P.O. Box 4300, Oulu 90014, Finland.
4. Professor, Fibre and Particle Engineering, Faculty of Technology, Univ. of Oulu, P.O. Box 4300, Oulu 90014, Finland.