A duct for conveying influent to a head cell having multiple, vertically aligned trays has an inlet end and an outlet end. In the method, a content description is received which comprises a content identifier, a publisher identifier, publisher authorization information and content checking information. By this means, the corrected envelope signal level becomes equal to or higher than the delayed envelope signal level, so that it is possible to prevent the power supply voltage from being lower than the optimal power supply voltage, making it possible to prevent the linearity of an output signal from deteriorating in power amplifier. The alignment motion necessary for alignment of the sheet material in the conveyor direction and perpendicular thereto takes placed by separate alignment elements which can be triggered independently of one another during conveyance of the sheet material with the process speed. The at least one controller sends signals to the microprocessor that the microprocessor uses to control the operation of the at least two wheels. The servicing spacecraft also has a universal docking adaptor for different client spacecraft, and can convert a client spacecraft from non-cooperative to cooperative.