"April 1993."
Supported by the Office of Naval Research under contract no. NOOO14-91-J-1422, P0002.
Supported by the National Aeronautics and Space Administration under grant NAG 1-1146.
Supported by the Department of Energy, contract no. DE-FG02-90ER60970.
Supported by the National Science Foundation contract no. ATM-9113129.
Includes bibliographical references (p. 74).