1. Information and Computer Science Department, King Fahd University of Petroleum & Minerals, Academic Belt Road, Dhahran 31261, Saudi Arabia
2. WMG, University of Warwick, 6 Lord Bhattacharyya Way, Coventry CV4 7AL, UK
3. Instituto Politécnico de Viana do Castelo, 4900-347 Viana do Castelo, Portugal
4. INESC TEC, 4200-465 Porto, Portugal