时间：2011-03-11 23:18来源：蓝天飞行翻译 作者：航空 点击：次
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parabolic microphone. An extremely sensitive microphone mounted at the focus of a parabolic sound reflector. The reflector is aimed at the source of sound to be picked up, and the parabolic surface reflects the sound waves, concentrating them at the microphone. parabolic reflector (light reflector). A light reflector whose surface is made in the form of a parabola. The filament producing the light is located at the focus of the parabola, and the light is reflected from the parabolic surface as a beam of parallel rays. parachute. A large umbrella-shaped device, made of lightweight cloth, used to slow an object falling through the air. Parachutes are folded into a pack and worn by a person who jumps from an aircraft. When the pack is opened, the parachute canopy is pulled out by the air and opens. The parachute creates so much drag that the wearer descends at a rate slow enough to prevent injury when contact is made with the ground. Cargo parachutes are used to lower equipment at locations where it is impractical for airplanes or helicopters to land. 14 CFR Part 1: “A device used or intended to be used to retard the fall of a body or object through the air.” par-al-ketone. A heavy wax-like grease, used to protect cables, bolts, and other types of fittings from rust and corrosion when they are exposed to water. Par-al-ketone is also used to protect metal objects that are to be stored for long periods of time. parallax. An optical (viewing) error caused by an object appearing to be in different locations when it is viewed from different angles. Parallax causes a pointer-type instrument to give an inaccurate indication unless it is viewed from directly above the pointer. Moving your head as you read the dial can give different indications. Precision instruments have a mirror built into the dial to prevent parallax error. When reading such an instrument, move your eye until the pointer is directly over its reflection. When viewed from this position there is no parallax. parallel access (digital computers). A method of accessing data from a computer in which all bits of the data are transferred at the same time. Parallel access is different from serial access, in which the data is transferred one bit at a time. parallel bus system (electrical power system). An electrical power system in which all of the operating generators are connected to a single power bus. parallel electrical circuit. A circuit in which the components are connected in such a way that there is more than one complete path for electrons to pass from the negative terminal of the power source back to its positive terminal. parallel ILS approaches (air traffic control). Approaches to parallel runways by IFR aircraft which, when established inbound toward the airport on the adjacent final approach courses, are radar-separated by at least two miles. |
