- Head, University of Illinois, Urbana-Champaign, Illinois, Department of Industrial and Enterprise Systems Engineering, August 2013- .
- Visiting Researcher, INRIA-Lorraine, Institut National de Recherché en Informatique et en Automatique,Nancy and Metz, France, summer 1988, 1989, 1990, 1991, 2002.
- Donald Biggar Willett Professor, University of Illinois, Urbana-Champaign, Illinois, Department of Industrial and Enterprise Systems Engineering, August 2013- .
- Chair, University at Buffalo, The State University of New York at Buffalo, Buffalo, New York, Department of Industrial and Systems Engineering, June 2006 – August 2012.
- Professor, University at Buffalo, The State University of New York at Buffalo, Buffalo, New York, Department of Industrial and Systems Engineering, August 2005 – August 2013.
- Associate Professor, University at Buffalo, The State University of New York at Buffalo, Buffalo, New York, Department of Industrial and Systems Engineering, September 1998 – August 2005.
- University at Buffalo Faculty Senate Committee, University at Buffalo, The State University of New York at Buffalo, Buffalo, New York, Department of Industrial and Systems Engineering, July 2002 – June 2004.
- Director of Graduate Studies, University at Buffalo, The State University of New York at Buffalo, Buffalo, New York, Department of Industrial and Systems Engineering, August 1999 – August 2001.
- Assistant Professor, University at Buffalo, The State University of New York at Buffalo, Buffalo, New York, Department of Industrial and Systems Engineering, September 1993 – August 1998.
- Research Associate, University of Maryland, College Park, Maryland, Institute for Systems Research, December 1991 – August 1993.