時間：2011-03-11 23:18來源：藍(lán)天飛行翻譯 作者：航空 點擊：次
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radial ply tire. A tire in which the body chords run straight across the tire. A belt of metal or synthetic cords is placed between the radial cords and the tread. radian. A measure of angular displacement. One radian is the angle formed by the arc of a circle whose length is equal to the radius of the circle. A complete circle (360°) contains two π (6.28318) radians, and one radian is equal to 360° divided by 6.28318, or 57.2958°. radiant energy. Energy transmitted in the form of waves of electromagnetic radiation. Light, heat, and radio-frequency electrical energy are forms of radiant energy. radiant heat. Heat transmitted in the form of waves of electromagnetic radiation, rather than by conduction or convection. The heat we receive from the sun is a form of radiant heat. radiation (electromagnetic). The transfer of energy in the form of electromagnetic waves through either air or the vacuum of space. See electromagnetic radiation. radiation (heat transfer). The method of heat transfer by electromagnetic wave action. radiation fog (meteorology). Fog that forms on a clear, calm night when the surface of the earth is cooled by radiation until the temperature of the air near the surface is below its initial dew point. radiation shield (gas turbine engine component). A layer of aluminum built into the insulation blanket used around the hot section and exhaust of a gas turbine engine. The radiation shield prevents heat being radiated from the engine into the aircraft structure. radical sign (mathematics). The mark in the shape of the letter V with a tail on it. A radical sign placed in front of and extending over a number shows that a root should be extracted from the number. If there is no number in the V-part of the radical sign, the square root of the number is indicated. Any number written in the V of the radical sign shows which root of the number is to be taken. radioactivity. A property or characteristic of certain unstable chemical elements in which they lose some of their neutrons. As they lose neutrons, they change into stable isotopes of the element or into atoms of other elements having different chemical properties. radio altimeter. A type of absolute altimeter that measures the height of an aircraft above the terrain. A pulse of radio-frequency energy is transmitted downward from the aircraft. This pulse strikes the ground and is reflected back up to the aircraft where it is received. The time used by the pulse in traveling from the aircraft to the ground and back is changed into feet or meters and is displayed before the pilot. Radio altimeters are sometimes called radar altimeters. radio control. Control of some type of mechanical device by electrical signals transmitted from a remote location. radio-frequency alternating current. Alternating current whose frequency is between about 10 kilohertz (10 x 103 hertz) and 100 gigahertz (100 x 109 hertz). Radio-frequency alternating current is used for various types of communications and navigation. |
