时间：2011-03-11 23:13来源：蓝天飞行翻译 作者：admin 点击：次
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holding relay. An electrical relay whose coil is in series with its contacts. The contacts are closed by sending a pulse of current through the coil, and the contacts remain closed until the current flowing through them is interrupted. hold-short point (air traffic control). A point on the runway beyond which a landing aircraft with a land and hold short (LAHSO) clearance is not authorized to proceed. The hold-short point may be located prior to an intersecting runway, taxiway, predetermined point, or approach/departure flight path. hold-short position lights (air traffic control). Flashing in-pavement white lights located at specific hold-short points. hold-short position marking (air traffic control). The painted runway marking located at the hold-short point on all land and hold short (LAHSO) runways. hold-short position signs (air traffic control). Red and white holding position signs located alongside the hold-short point. hole (semiconductor device). A concept used to explain the action that takes place in a semiconductor material. A hole is a location in a covalent atomic bond where there should be an electron, but where there is none. Holes are the mobile charges in a piece of P-type semiconductor material, and since they are located where an electron (a negative charge) should be, they act as positive charges. See acceptor atom. hole finder (sheet metal hand tool). A hand tool used in sheet metalwork that allows a technician to locate a rivet hole in a new sheet metal skin so the hole will be directly in line with a hole already existing in the structure being repaired. hollow drill. A drill with a hole through its center. Air or liquid lubricant can be pumped through a hollow drill into the hole being drilled, to make it easier for the drill to cut, and to remove chips from the hole. |
