Hello, Goodbye.

* Army Gen. David G. Perkins retired in March after 37 years of service, most recently as commanding general of Training and Doctrine Command. Gen. Stephen J. Townsend assumed his duties at TRADOC earlier in the month.

The U.S. Army Research Laboratory selected Jaret C. Riddick as the new director of its vehicle technology directorate, a 120-person operation that pursues mobility-related science and technology for both air and ground platforms.

Rear Adm. Shane G. Gahagan was named program executive officer for tactical aircraft programs. Gahagan is currently serving as commander of the Naval Air Warfare Center, aircraft division; and assistant commander for research and engineering, Naval Air Systems Command at Patuxent...