An active cache, for use by On-Line Anaytic Processing systems, that can not only answer queries that match data stored in the cache, but can also answer queries that require aggregation or other computation of the data stored in the cache. The system includes a data communication server, having a plurality of interface units, for facilitating data communication between a moving object and one or more ground terminals via a radio communication path. This receiving pocket may be arranged so that the drive element is inserted coaxially with respect to the pivot axis of the flap or transversely thereto, or if the receiving pocket extends into the interior of the duct, the pivot flap is provided with a corresponding cut-out. The system allows a user to select desired execution icons from an icon select palette that provides lists of execution icons which are registered in advance. The cushion includes a blanket for covering the infant adapted to be placed on the top surface. A frequency bin echo path characteristic estimator uses the far-end signal amplitude spectrum in the frequency bins determined to have a frequency component by the frequency bin component detector and the near-end input signal amplitude spectrum of corresponding frequency bins to estimate the echo path characteristics of the frequency bins.