1. Hydro- and Environmental Engineering Faculty, Technical University of Gdansk, Narutowicza 11/12, 80-952 Gdańsk, Poland, (e-mail: kola@pg.gda.pl)
2. Centrum Badawczo-Wdrożeniowe UNITEX Sp. z o.o., Lęborska 9, 80-386 Gdańsk, Poland, (e-mail:piotrczescik@poczta.wp.pl)