A discharge voltage detecting unit 7 detects a discharge voltage and determines an average discharge voltage in a specified period of time. Sensors are deployed at a theatrical event to detect a focusing signal andor the RF signal of an unauthorized imaging device. A known location of limited size is defined in the flash RAM, to form a scratchpad. View information is derived from the resource record. The selected encoded AV streams are communicated utilizing segment-based adaptive streaming techniques such as HTTP. And, a combustion air channel passing the compressor, the combustor and the turbine and a cooling air channel passing the radiator, the cooling fan and the electric power converter are formed as mutually independent channels from intake to exhaust.