1. Department of Computer Science, Royal Holloway, University of London, Egham, TW20 0EX, UK. E-mail: {ozgur.kafali,ulrich.schaechtle,kostas.stathis}@cs.rhul.ac.uk
2. Department of Business Information Systems, University of Applied Sciences Western Switzerland, 3 Technopole, 3960, Sierre, Switzerland. E-mail: {stefano.bromuri,bruno.alves,damien.zufferey,michael.schumacher}@hevs.ch
3. Portavita B.V., Oostenburgervoorstraat 100, PO Box 1287, 1000 BG, Amsterdam, The Netherlands. E-mail: {m.sindlar,t.van.der.weide}@portavita.eu
4. Electrical and Electronic Engineering Department, Imperial College London, South Kensington Campus, London, SW7 2BT, UK. E-mail: {eduardo.aguilar-pelaez02,e.rodriguez}@imperial.ac.uk