An ear plug system according to various embodiments can include an ear plug device and an electronic control unit. The device comprises a carrier, at least one jaw for exerting contact pressure on the workpiece, and a linear guide for guiding the jaw. An image analysis component estimates an ensquared energy value for the imaging system from respective intensity values of the associated pixels and known relative positions of the plurality of point sources. Outputs from the normal processor and positioncolor processor are multiplexed to a format converter. For example, the RF metal detector can be integrated with an EAS system that also sends RFID commands and receives RFID responses. The air conditioning device comprises a compressor connected to an output shaft of an engine via an electromagnetic clutch, a motor-generator for electrically recovering kinetic energy of the vehicle during deceleration, a battery for storing energy regenerated by the motor-generator, and a motor-driven compressor.