1. Asst. Prof. of Civ. Engrg., Massachusetts Inst. of Tech., Cambridge, Mass., on leave of absence; presently 1st Lt., U. S. Army, Chf., Advanced Systems Concepts Office, Military Traffic Mgt. and Terminal Service, Washington, D. C.
2. Asst. Prof. of Civ. Engrg., Massachusetts Inst. of Tech., Cambridge, Mass.
3. Senior Research Scientist, Commonwealth Scientific and Industrial Research Org., Melbourne, Australia; formerly, Assoc. Prof. of Civ. Engrg., Massachusetts Inst. of Tech., Cambridge, Mass.