1. AC2T research GmbH, Viktor-Kaplan-Straße 2/C, 2700 Wiener Neustadt, Austria
2. Institute of Engineering Design and Product Development, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria
3. Department of Mechanical Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, U.K.