First Author:   Andreas Humpe University of Applied Sciences Munich humpe@hm.edu   Schachenmeierstrasse 35 Munich, 80636, Germany   +49 89 1265 2112(Phone) +49 89 1265 2112(Fax) www.hm.edu Second Author: David McMillan University of Stirling david.mcmillan@stir.ac.uk