Level

(redirected from background level)
Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Wikipedia.

level:

see spirit levelspirit level,
tool for determining whether a surface is horizontal. It consists essentially of a slightly bent transparent tube that is held in a frame. The tube contains some alcohol, ether, or similar fluid but is not entirely filled, so that it also contains a small bubble.
..... Click the link for more information.
.

Level

 

(gorizont, horizon), in mining, the totality of mining developments located at one level and designed for carrying on mining work. By their purpose in the mine the following levels are distinguished: the hauling level (for transporting loads and moving people), the airway level (for ventilating the mine), the discharge level (for discharging broken-up ore), the cutting level (for opening up a rock mass from below in order to cave it in or break it up), and the scraper level (for scraper delivery of broken-up minerals to the loading point). For open-pit extraction of minerals the primary mining equipment for working one bench is installed on a level (the so-called work level of the quarry).


Level

 

a geodetic instrument used for measurement of the elevation of points on the earth’s surface (leveling) and for establishing horizontality during erection and installation operations. The most common levels are opticomechanical levels, which have a sighting tube that is used for readings from a rod. Before taking the reading, the sight line of the sighting tube is set on the horizontal by means of the spirit level; in levels with self-leveling sight lines, this is done automatically.

Leveling instruments with spirit levels are mainly required to provide a near-parallel relative position of the sight line and the axis of the spirit level that must remain sufficiently stable over time and upon changes in temperature. Such a relationship is achieved through adjustment of the instrument, which must be done frequently. Many types of leveling instruments have been built, primarily to simplify adjustment; they differ in the type of interconnection of their three basic parts (the sighting tube, the spirit level, and the stand). For example, the spirit level may be mounted on the tube, which is laid across the stand, or it may be mounted on the stand. However, dumpy levels, in which both the spirit level and the tube are rigidly connected to the stand, have proved most stable and become most common. Dumpy levels are often made with lifting screws, or elevation screws, to

Figure 1. Diagram of a dumpy level with an elevation screw: (1) sighting tube, (2) lens, (3) crosshairs, (4) eyepiece, (5) sight line, (6) level axis, (7) spirit level, (8) horizontal axis, (9) elevation screw, (10) balance spring of elevation screw, (11) vertical axis, (12) carrier with lifting screws

make it easier to set the spirit-level bubble at the zero point and to increase the precision of the instrument (see Figure 1). In this type of arrangement, all the parts that connect the sighting tube to the horizontal axis form the stand. A distinction is made among high-precision, precision, and engineering levels, which produce errors not greater than 0.5–1.0 mm, 5–8 mm, and 15 mm, respectively, per kilometer of level line.

Hydrostatic levels, based on the principle of communicating vessels, are sometimes used. There have been many attempts to make automatic levels, which determine elevation by integrating the angles of dip along a route traveled across the terrain by bicycle, motor vehicle, or other vehicle; however, as of 1974 the results have not been acceptable.

REFERENCES

GOST 10528–69, Niveliry.
Gusev, N. A. Marksheidersko-geodezicheskie instrumenty ipribory, 2nd ed. Moscow, 1968.
Deimlikh, F. Geodezicheskoe instrumentovedenie. Moscow, 1970.

G. G. GORDON


Level

 

in linguistics, any one of the basic planes of a language system—phonemes, morphemes, words (lexemes), and phrases (tagmemes)—considered as objects of linguistic analysis and constituting the province of phonology, morphology, lexicology, and syntax. Levels of language are determined by the characteristics of units isolated in the continuous articulation of running speech. Some scholars seek to increase the number of levels by raising to the status of a separate level any of the complex units capable of isolation; others consider only two levels to be significant—the differential and the semantic.

On the differential level, language appears only as a system of contrasting signs that include, besides the natural sounds of speech, the written signs that distinguish units on the semantic level. On the semantic level, morphemes, words, and combinations of words are distinguished as two-sided units, that is, with regard to their acoustic aspect, or expression, and to their internal, semantic, aspect, or content.

REFERENCES

Urovni iazyka i ikh vzaimodeistvie: Tezisy nauchnoi konferentsii (Apr. 4–7, 1967). Moscow, 1967.
Martinet, A. “Arbitraire linguistique et double articulation.” Cahiers Ferdinand de Saussure, 1957, no. 15.
Benveniste, E. “Les Niveaux de l’analyse linguistique.” In Proceedings of the Ninth International Congress of Linguists. The Hague, 1964.
Buyssens, E. “La Sextuple Articulation du langage.” Ibid.

O. S. AKHMANOVA


Level

 

an instrument for checking the horizontal position of planes and for measuring small angles. A level consists of a bar with a vial located inside; the vial is filled with alcohol or ether, except for a small gas bubble. If the lower plane of the level is positioned horizontally, the bubble will rest in the center of the vial. Levels with two vials can be used simultaneously to check the horizontal position of two planes that are mutually perpendicular. Some levels have the shape of a cylinder, the top of which is hermetically sealed by glass. The inside of the glass is spherically ground, and the box is filled with a fluid with a gas bubble. If the base of the box is positioned on a true horizontal, the bubble will rest in the center of the glass cover.

Levels used in machine building include mechanic’s levels and frame levels. In the former, the leveling vial is equipped with a scale and mounted within the housing. The level also has a fixture that adjusts the location of the vial with respect to the base of the housing. The position of the end of the bubble on the scale defines the inclination angle of the plane on which the level is placed. A prismatic recess in the base makes it possible to mount the level on cylindrical surfaces. A frame level consists of a four-sided frame with precise right angles; the leveling vial and the adjusting fixture are located in the lower part of the frame. Frame levels can be used on horizontal or vertical surfaces.

Levels with one or two leveling vials are used in construction work to check the correct location of parts of the buildings and structures being erected.

Levels are an important tool in astronomy, geodesy, and physics. They are used in leveling, in determining the inclination angles of horizontal axes, and in measuring the change of the angle between the vertical axis and a sighting line. Levels used in astronomy have a scale for angle measurements marked on the vial; the scale divisions are usually in units between 1 minute and 1 second.

REFERENCES

Gorodetskii, Iu. G. Konstruktsii, raschet i ekspluatatsiia izmeritel’nykh instrumentov ipriborov. Moscow, 1971.
Blazhko, S. N. Kursprakticheskoi astronomii, 3rd ed. Moscow, 1951.

level

[′lev·əl]
(civil engineering)
A surveying instrument with a telescope and bubble tube used to take level sights over various distances, commonly 100 feet (30 meters).
To make the earth surface horizontal.
(communications)
A specified position on an amplitude scale (for example, magnitude) applied to a signal waveform, such as reference white level and reference black level in a standard television signal.
(computer science)
The status of a data item in COBOL language indicating whether this item includes additional items.
(design engineering)
A device consisting of a bubble tube that is used to find a horizontal line or plane. Also known as spirit level.
(electricity)
A single bank of contacts, as on a stepping relay.
(electronics)
The difference between a quantity and an arbitrarily specified reference quantity, usually expressed as the logarithm of the ratio of the quantities.
A charge value that can be stored in a given storage element of a charge storage tube and distinguished in the output from other charge values.
(mining engineering)
Mine workings that are at the same elevation.
A gutter for the water to run in.
(statistics)
In factorial experiments, the quantitative or qualitative intensity at which a particular value of a factor is held fixed during an experiment.

level

1. A surveying instrument for measuring heights with respect to an established horizontal line of sight; consists of a telescope and attached spirit level, a rotatable mounting, and a tripod. Also see wye level and dumpy level.
2. The position of a line or plane when parallel to the surface of still water.
3.See spirit level.
4. Of an acoustical quantity, 10 times the logarithm (base 10) of the ratio of the quantity to a reference quantity of the same physical kind.

level

level
i. A generic term relating to vertical position of an aircraft in flight and meaning variously, height, altitude, or a flight level (ICAO).
ii. To bring an aircraft into a horizontal line of flight, such as in to level off or level out.

level

1. Engineering a device, such as a spirit level, for determining whether a surface is horizontal
2. Geography any of the successive layers of material that have been deposited with the passage of time to build up and raise the height of the land surface
3. Physics the ratio of the magnitude of a physical quantity to an arbitrary magnitude
References in periodicals archive ?
The exposure results (Figure 3) reveal that a single 6-hr inhalation exposure to a steady-state of 1 ppm acrolein in HEPA-filtered air was sufficient to increase acrolein--dG adduct levels in aortic DNA by about 5 times over background levels.
There have been very few incidents where there has been a below background level of NORM.
runoff from landfills, compost, brush or silage piles, or chemicals such as gasoline) can add to the background level by increasing manganese release from soil or bedrock into groundwater.
The background level before loudspeakers were used was from about 59 to 61dB.
As for the rest, a certain background level of shambles is perhaps to be expectedatsuchahugeevent buttheproblemsyouname weresurelyavoidable.
But sudden change like cooking fish, for example, would change the background level and trigger the detector.
Despite increasingly stringent controls on our use of antibiotics, the background level of antibiotic resistant genes continues to rise in soils.
The samples just over the known Trilogy resource carried gold values up to 10 times the background level (highest value was 96ppb Au).
The GOES flare data shows small flares in January and April during our night-time, but otherwise there is just a very low background level of X-ray flux.
This comprehensive and practical text, suitable for reference and classroom use, covers virtually every facet of the industry, from marketing to producing to getting into the Writers Guild of America, and also provides a legal overview of intellectual property, personal rights, financing and regulations at a background level.
Scaled to the real geometry the results obtained correspond to a fast neutron background level of [approximately equal to]5 %.
Aluminum is so common that all of us have some background level in our bodies.

Full browser ?