Abstract: An addressable speaker system in which a plurality of selectively activated speakers are distributed throughout a predefined area and are connected to a central processing unit. The system contains multiple RF antennas that are capable of broadcasting and receiving radio frequency signals to individuals wearing radio frequency identification (RFID) badges. The system users the RF transmission to locate an intended radio frequency identification badge and selectively broadcasts an audio message to a speaker located closest to the intended recipient.

Abstract: The grid member is formed of sheet metal and has an inverted T-shape with a bulb at the top, a double thickness central web and oppositely disposed flanges at the bottom. To achieve controlled expansion, two parallel lances are cut along opposite sides of the bulb near the top of the bulb. No metal is removed at this area of maximum bending stress. Further, staggered cutouts are placed in the two thicknesses which make up the web. By staggering the cutout areas of adjacent web layers, the overall web strength is maintained. These web cutouts and the lance at the top of the bulb cooperate upon thermal expansion, causing the bottom flanges to buckle down, and the web and sides of the bulb to separate laterally and fold, and the top of the bulb to buckle up. The folded web configuration directed by the staggered cutout pattern will maintain longitudinal rigidity.

Abstract: The grid member is formed of sheet metal and has an inverted T-shape with a bulb at the top, a double thickness central web and oppositely disposed flanges at the bottom. To achieve controlled expansion, an extended angular lance is cut at the top of the bulb. No metal is removed at this area of maximum bending stress. Further, staggered cutouts are placed in the two thicknesses which make up the web. By staggering the cutout areas of adjacent web layers, the overall web strength is maintained. These web cutouts and the lance at the top of the bulb cooperate upon thermal expansion, causing the bottom flanges to buckle down, and the web and bulb to separate laterally and fold. The folded web configuration directed by the staggered cutout pattern will maintain longitudinal rigidity.