时间：2011-03-11 23:11来源：蓝天飞行翻译 作者：admin 点击：次
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An aperiodically damped pendulum will not swing back and forth, but will stop just as it reaches its at-rest position. Aperiodic damping is also called dead-beat damping. aperture antenna. An antenna whose beam width is controlled by the size of the reflector, horn, or lens used. API scale. A scale developed by the American Petroleum Institute to measure the specific gravity of a liquid. apogee. The point at which an orbiting vehicle is the greatest distance from the center of the object it is circling. apparent power (electrical power). The power in an alternating-current circuit which is the product of the total current and the source voltage. Apparent power, measured in volt-amps, must be multiplied by the power factor to get true power in watts. apparent weight. The weight of an object when it is immersed in a liquid. It is the weight of the object, less the weight of the liquid it displaces, and is the difference between the force of gravity acting downward on the object and the buoyant force produced by the liquid acting upward. appliance. Any device used in the operation of an aircraft that is not a part of the airframe, engine, or propeller. Pumps, actuators, generators, instruments, and radio receivers and transmitters are all examples of appliances. 14 CFR Part 1: “Any instrument, mechanism, equipment, part, apparatus, appurtenance, or accessory, including communications equipment that is used or intended to be used in operating or controlling an aircraft in flight, is installed in or attached to the aircraft, and is not part of an airframe, engine, or propeller.” approach. The part of an aircraft flight in which the aircraft is positioned in such a way that it can touch down at the correct part of the runway on landing. approach clearance. Authorization by Air Traffic Control for a pilot to conduct an instrument approach. approach control facility. A terminal Air Traffic Control facility that provides approach control service in a terminal area. approach control service (air traffic control). Air traffic control provided by an approach control facility for arriving and departing VFR/IFR aircraft and, on occasion, en route aircraft. At some airports not served by an approach control facility, the ARTCC provides limited approach control service. approach gate. A point on the final approach course which is one mile from the final approach fix on the side away from the airport or five miles from the landing threshold, whichever is farther from the landing threshold. approach lights. High-intensity lights located along the approach path at the end of an instrument runway. Approach lights aid the pilot in transitioning from instrument flight conditions to visual conditions at the end of an instrument approach. approach sequence (air traffic control). The order in which aircraft are positioned while on approach or awaiting approach clearance. approach speed. The recommended airspeed listed in the aircraft manual to be used by pilots when making an approach for landing. |
