1. Lappeenranta University of Technology , Lappeenranta , Finland
2. LUT Savo Sustainable Technologies, Lappeenranta University of Technology, Varkaus unit, Osmajoentie 75 , Varkaus , Finland
3. UPM Research Centre , Lappeenranta , Finland
4. University of Jyväskylä , Jyväskylä , Finland