1. Postdoctoral Associate, Dept. of Aeronautics and Astronautics, Massachusetts Institute of Technology, 77 Massachusetts Ave., Office 17-110, Cambridge, MA 02139.
2. Professor, Civil and Environmental Engineering and Engineering Systems, Massachusetts Institute of Technology, One Amherst St., Office E40-245, Cambridge, MA 02139.
3. Professor, Aeronautics and Astronautics and Engineering Systems, Massachusetts Institute of Technology; and Director, MIT International Center for Air Transportation, 77 Massachusetts Ave., Office 33-308, Cambridge, MA 02139.