There is provided a system to provide a sequence of motion samples to a plurality of motion platforms, such as the plurality of seats in a movie theatre, such that the motion is synchronized with a sequence of images, such as a movie. The arrangement includes a duct extending to above the roof of the building. Next, the process creates an infra-red thermal mapping of a cathode region of the FED. A reference to the opportunistically locked file object is cached. The tensioning means comprises: a cylinder having one end open to sea pressure, having an opposite end sealed from sea pressure, and connected to one end of the marine riser; a piston within the cylinder disposed for movement within the cylinder; and a piston rod passing through the opposite end of the cylinder and having one end connected to the other end of the marine riser. A ring list used for tuning channels in channel updown tuning operations is generated which contains only those scanned channels determined to have decodable video or audio content.