1. State Key Laboratory of Hydraulic Engineering Simulation and Safety, and School of Computer Science and Technology, Tianjin University, Tianjin 300072, China e-mail:
2. Department of Mathematics and Computer Science, Eindhoven University of Technology, Eindhoven 5600MB, The Netherlands e-mail:
3. Hydromechanics Laboratory, Department of Civil Engineering, Middle East Technical University, Ankara 06800, Turkey e-mail: