When discharge power calculated based on a current value detected by a current detector is smaller than expected maximum power, which is the maximum power expected in an actual operation, a discharge efficiency at the expected maximum power is set as a discharge efficiency used for remaining capacity calculation. Initially, system communications domains in which system hardware resources are located are identified. The primary use is with dogs, but all kinds of domestic animals may be trained using this device. When mail is inserted, the door is pushed upwardly and inwardly after which the door swings back to the closed position automatically under the force of gravity. The lower part is pivotable in the winding direction such that unwinding of the rope from the pulley is prevented, but can be wound onto the pulley in the functional position. Microorganisms capable of degrading or transforming POPs are actively associated with the substrata as a biofilm.