Visiting researcher, the Fields Institute, Toronto, Canada, September 2016- August 2017 (Hosts: Professors Almut Burchard and Robert MCcann).
Visiting Professor, The Royal Institute of Technology, Sweden, June 1-June 7, 2009.(Host: Professor H. Shahgholian)
Visiting professor, The University of Cagliari, Italy, July 3-24, 2005 (Host: Professor G. Porru).
Visiting Scholar, The Royal Institute of Technology, Sweden, May 1-18, 2004 (Host: Professor H. Shahgholian).
Lebanese University and the American University in Beirut, October 21-28, 2002 (Hosts: Professors M. Jazar and A. Shamsseddin).