1.      Graduate teaching and research assistantship in City University of New York, USA from 1990 to1995

2.      Research assistantship at Center of materials science and technology (MARTECH) in Florida State 
      University (FSU), USA in 1995/1996 
3.      Postdoctoral fellowship at department of mechanical, industrial and manufacturing engineering in The  
      University of Toledo, Ohio, USA from 2007 June to 2007 December.