forceair空军magazine杂志usaf AIR FORCE Magazine / May 2013 36 How the Air Force Is Organized This overview describes the Air Force’s primary organizational struc- tures and its Air and Space Expedi- tionary Force. The Department of Defense is a Cabinet agency headed by the Secre- tary o De...
Circumferential Excitation According to the excitation principle, two force loads are added sequentially to two adjacent zones with equal axial length of /4, where is the wavelength. The two loads have the same time duration, but with a time shift of T0/4 one after the other, where T0 is ...