[1] Slovak Univ Technol Bratislava, Fac Civil Engn, Radlinskeho 2766-11, Bratislava 81005, Slovakia
[2] ICA, Slovak Acad Sci, Dubravska Cesta 9, Bratislava, Slovakia
[3] Katholieke Univ Leuven, Dept Phys & Astron, KU Leuven, B-3000 Leuven, Belgium
[4] Politecn Torino, Dept Energy, Corso Duca Abruzzi 24, I-10129 Turin, Italy
[5] Mendel Univ Brno, Fac Forestry & Wood Technol, Zemedelska 3, Brno 61300, Czech Republic