| 摘要 |
A panel having selectively variable radiation and vibration transmitting properties comprising a substantially two-dimensional normally transparent or translucid hollow structure for receiving therein low density particulate material having predetermined thermal and/or optical characteristics, said hollow structure having an uppermost part and a lowermost part and said lowermost part having at least one end portion, the particulate material being fed into said hollow structure through the uppermost part thereof and withdrawn from said hollow structure through said end portion of the lowermost part thereof for varying the radiation and vibration transmitting properties of the panel, a multi-perforated plate member defining the bottom wall of said hollow structure, the multiplicity of perforations thereof communicating the interior and exterior thereof, said plate member being shaped to have alternative crests and valleys, said crests and valleys being formed by areas of said wall facing towards and away from said end portion, the perforations in said bed member extending only through said areas facing said end portion so that air injected into said space through said perforations will blow particulate material resting on said bed member towards said end portion, while said areas facing away from said end portion help to direct said blown particulate material towards said end portion thus enhancing evacuation of said space.
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