1. Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
2. Institute of Materials Science and Engineering, Brno University of Technology, Technicka 2, 616 69 Brno, Czech Republic
3. Institute of Rock Structure and Mechanics of the Czech Academy of Sciences, V Holešovičkách 94/41, 182 09 Praha, Czech Republic