航空術(shù)語(yǔ)詞典Dictionary of Aeronautical Terms 中

時(shí)間：2011-03-11 23:13來(lái)源：藍(lán)天飛行翻譯 作者：admin 點(diǎn)擊：次

The compressor forces the hot gas through the condenser, located outside the aircraft. Here, the gas transfers some of its heat to the outside air and condenses back into a liquid. Heat in this way is pumped from inside the aircraft cabin to the air outside the aircraft.
heat-shrinkable fabric. Certain inorganic fabrics used to cover aircraft structure. The fabric used for this purpose is sold in its unshrunk state and is put on the structure so that it is taut, but not tight. After it is secured to the structure with a special adhesive, it is shrunk to the correct tautness by ironing it with an electric iron or blowing it with a special heater/blower.
After the fabric has the correct tautness, it is coated with a non-tautening dope. Organic fabrics, such as cotton and linen, are not heat-shrinkable and are shrunk on the structure with a shrinking-type dope.
heat sink. A piece of heavy metal on which such electrical components as power transistors are mounted. Heat from the component is transferred into the heat sink by conduction, and from there it is dissipated into the surrounding air. A silicone grease may be spread between the component and the heat sink to help transfer the heat.
Many heat sinks on which high-power components are mounted have fins to increase their cooling area.
heat treatment (metal). A process by which certain types of metal are hardened or softened by heat. Most metals containing iron can be hardened by heating them to a high temperature and quenching them in water, brine (a solution of salt and water), or oil. These same metals can be softened by heating them to a high temperature and allowing them to cool slowly in an oven.
Copper cannot be hardened with heat. When copper is heated red-hot and quenched in water, it becomes soft. Metals that cannot be hardened with heat can be work hardened by bending, hammering, rolling, or stretching. However, most of these metals can be softened by heating them and cooling them slowly.
heat treatment (plastic resins). A process used to strengthen cemented joints in thermoplastic resins. After the cemented joint is completed, the material is held at an elevated temperature (not high enough to distort the material) for a specified period of time.
The heat causes solvents concentrated in the joint to diffuse (to spread evenly) throughout the material. This diffusion decreases the concentration of the solvents in the joint and increases its strength.
Heaviside layer (atmosphere). A layer of ionized particles that surrounds the earth at a height of about 55 to 85 miles above the surface. The Heaviside layer is also called the Kennelly Heaviside layer and the E-region of the atmosphere. The Heaviside layer reflects relatively long, low-frequency radio waves.
heavy ends (petroleum refining). The components of crude petroleum that have the highest boiling points.
In the process of fractional distillation, the lighter products boil off first and are condensed. The heavy ends are the parts of the petroleum that boil off last.

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