1. Visiting Professor, Dept. of Computer Science and Engineering, Carlos III Univ. of Madrid, Av. Universidad 30, 28911 Madrid, Spain (corresponding author).
2. Professor, School of Civil, Structural, and Environmental Engineering and Earth Institute, Univ. College Dublin, Newstead G25, Belfield, Dublin 4, Ireland; Center for Urban Science and Progress, New York Univ., 1 Metrotech Center, Brooklyn, NY 11201.
3. Associate Professor, Dept. of Computer Science and Engineering, Carlos III Univ. of Madrid, Av. Universidad 30, 28911 Madrid, Spain.