Persson, Lars-Erik
Oinarov, Ryskul
Shaimardan, Serikbol
Funding for this research was provided by:
LuleƄ Tekniska Universitet
Article History
Received: 13 December 2017
Accepted: 17 March 2018
First Online: 4 April 2018
Competing interests
: The authors declare that they have no competing interests.