1. Department of Architecture and Civil Engineering, Chalmers University of Technology, 412 96 Göteborg, Sweden
2. Department of Mathematical Sciences, Chalmers University of Technology, 412 96 Göteborg, Sweden
3. Department of Electrical and Computer Engineering, Aristotle University, 541 24 Thessaloniki, Greece
4. School of Business, Economics and IT, Division of Informatics, University West, 461 32 Trollhättan, Sweden