Abstract: A modular sign assembly includes a perimeter frame including an upper support, a lower support, a first lateral support and second lateral support. Each of the upper and lower supports is removably engaged with each of the first and second lateral supports. The first and second lateral supports each include a housing having a top end, a bottom end and a perimeter wall. A light emitter is mounted in the housing and emits light outwardly from the perimeter wall when the light emitter is turned on. A rechargeable battery is mounted within the housing and is electrically coupled to the light emitter. Each of the first and second lateral supports has a receivers attached thereto and each receiver receives two legs. A flexible panel is positioned within the perimeter frame. A plurality of couplers releasably couples the flexible panel to the perimeter frame.

Abstract: An acoustic source is provided where a high pressure fluid is used to positively control the period an exhaust valve is open. High pressure fluid is introduced to the control chamber at a predetermined instant after the exhaust valve or shuttle has been opened. This results in conservation of air used to fire the acoustic source and also to achieve a desired signature.