The present invention is a door opener operable to open doors of various weights, heights and widths, comprising cables attached to the door and further attached to an operation unit. The operation unit incorporates a telescoping section driven to extend and compress by the function of a fluid pump. The telescoping section comprises two or more telescoping portions. The extension of at least one telescoping portion creates tension in the cables and causes the door to be moved from a closed or semi-closed position to an open or semi-open position. The compression of at least one telescoping portion reduces tension in a constant or near-constant manner so that the door is caused to move from an open or semi-open position to a closed position or semi-closed position. The pump only requires power while at least one telescoping portion is extending and therefore power is only required while the door is being moved towards an open position.

The present disclosure provides a vibration power generation device capable of generating large electric power relative to an amount of displacement of a portion of a specimen. Vibration power generation device according to the present invention includes piezoelectric part and displacement enhancer. In response to displacement of a portion of specimen, displacement enhancer displaces a portion of piezoelectric part by a displacement amount greater than an amount of the displacement of the portion of specimen. When the portion of piezoelectric part is displaced, piezoelectric part generates electric power in accordance with an amount of the displacement of the portion of piezoelectric part.

The present invention is a door opener operable to open doors of various weights, heights and widths, comprising cables attached to the door and further attached to an operation unit. The operation unit incorporates a telescoping section driven to extend and compress by the function of a fluid pump. The telescoping section comprises two or more telescoping portions. The extension of at least one telescoping portion creates tension in the cables and causes the door to be moved from a closed or semi-closed position to an open or semi-open position. The compression of at least one telescoping portion reduces tension in a constant or near-constant manner so that the door is caused to move from an open or semi-open position to a closed position or semi-closed position. The pump only requires power while at least one telescoping portion is extending and therefore power is only required while the door is being moved towards an open position.