jet

jet

¹

1. a jet-propelled aircraft

2. Astronomy a long thin feature extending from an active galaxy and usually observed at radio wavelengths

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jet

²

a. a hard black variety of coal that takes a brilliant polish and is used for jewellery, ornaments, etc.

b. (as modifier): jet earrings

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

jet

A long thin linear feature of bright emission extending from a compact object, such as a galaxy. Jets are very common at radio wavelengths, but have also been seen in optical and X-ray emission. They are sometimes broken up into a number of bright knots. In extragalactic sources a jet is usually associated with the presence of an active galactic nucleus. An example is that found in the giant elliptical galaxy M87 (see Virgo A). See also radio-source structure.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Jet

 

a variety of pit coal; it is tough and has a deep black color, a strong, dull luster, and a flinty fracture. Its hardness on the mineralogical scale is 3-3.5; its density is approximately 1,300-1,400 kg/m³.

The formation of jet is associated with the metamorphism of wood buried in marine silts of Mesozoic and Cenozoic deposits. It is found in the form of separate aggregates or pieces in sandstones and marls, as well as in layers of weakly metamorphosed bituminous coal and lignite. Jet is easily worked and takes on a handsome luster when polished; because of this quality it is widely used (especially in the countries of the East) for small articles of jewelry, beads, and rosary beads.

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Jet

 

a calibrated opening used to meter the supply of liquid fuel or air. In the technical literature the term “jet” is used to designate carburetor parts with calibrated openings (plugs or injectors). According to their operational functions and the type of carburetor in which they are installed, jets may be classified as fuel jets, air jets, main jets, compensating jets, or idling jets. Jets are rated by their transmissive capacity—that is, the quantity of a liquid (usually water) that can pass through the calibrated opening per unit time. The transmissive capacity of jets is measured in cm³/min.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

jet

[jet]

(astronomy)

A narrow, elongated feature in the radio or optical map of an active galaxy, quasar, or object in the Milky Way Galaxy, believed to represent an energetic outflow of gas from a compact astronomical object.

(fluid mechanics)

A strong, well-defined stream of compressible fluid, either gas or liquid, issuing from an orifice or nozzle or moving in a contracted duct.

(particle physics)

A group of particles issuing in approximately the same direction from a high-energy collision of elementary particles, believed to consist of decay products of a member of a quark-antiquark pair created in the collision.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

jet

i. An aircraft powered by one or more gas turbine engines.
ii. A gas turbine engine may be referred to as a jet engine.
iii. A strong, well-defined stream of fluid either issuing from an orifice or moving in a contracted duct, such as the jet of combustion gases issuing from a reaction engine or the jet in the test section of a wind tunnel. A jet is also a forceful stream of fuel discharged from a small nozzle. Normally referred to as a jet-stream.
iv. A calibrated, restricted orifice, tube, nozzle, or the like through which metered fluid passes, or from which it issues, in a jet—such as a jet in a carburetor. The size of the jet and the pressure across the nozzle determine the quantum of fuel flow.
v. A narrow band of high-velocity wind in the upper troposphere normally referred to as a jet stream.

An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

Jet

(Joint Engine Technology) The database engine used in Microsoft Access and that accompanies Visual Basic and C++. Jet is typically used for storing data in the client machine. Developers using Access and Visual Basic access Jet via the DAO/Jet interface, which is a COM object. See DAO.

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