Crossword clues for compression
The Collaborative International Dictionary
Compression \Com*pres"sion\, n. [L. compressio: cf. F. compression.]
The act of compressing, or state of being compressed. ``Compression of thought.''
--Johnson.-
(Computers) reduction of the space required for storage (of binary data) by an algorithm which converts the data to a smaller number of bits while preserving the information content. The act of compressing [3].
Note: Compression may be lossless compression, in which all of the information in the original data is preserved, and the original data may be recovered in form identical to its original form; or lossy compression, in which some of the information in the original data is lost, and decompression results in a data form slightly different from the original. Lossy compression is used, for example, to compress audio or video recordings, and sometimes images, where the slight differences in the original data and the data recovered after lossy compression may be imperceptable to the human eye or ear. The JPEG format is produced by a lossy compression algorithm.
Douglas Harper's Etymology Dictionary
c.1400, from Middle French compression (14c.), from Latin compressionem (nominative compressio) "a pressing together," noun of action from past participle stem of comprimere "to squeeze" (see compress (v.)). Related: Compressional. Compressional wave is attested from 1887.
Wiktionary
n. 1 An increase in density; the act of compressing, or the state of being compressed; compaction. 2 The cycle of an internal combustion engine during which the fuel and air mixture is compressed. 3 (context computing English) The process by which data is compressed.
WordNet
n. an increase in the density of something [syn: compaction, concretion, densification]
the process or result of becoming smaller or pressed together; "the contraction of a gas on cooling" [syn: condensation, contraction]
encoding information while reducing the bandwidth or bits required [ant: decompression]
applying pressure [syn: compressing] [ant: decompression]
Wikipedia
Compression may refer to:
In mechanics, compression is the application of balanced inward ("pushing") forces to different points on a material or structure, that is, forces with no net sum or torque directed so as to reduce its size in one or more directions. It is contrasted with tension or traction, the application of balanced outward ("pulling") forces; and with shearing forces, directed so as to displace layers of the material parallel to each other. The compressive strength of materials and structures is an important engineering consideration.
In uniaxial compression the forces are directed along one direction only, so that they act towards decreasing the object's length along that direction. The compressive forces may also be applied in multiple directions; for example inwards along the edges of a plate or all over the side surface of a cylinder, so as to reduce its area (biaxial compression), or inwards over the entire surface of a body, so as to reduce its volume.
Technically, a material is under a state of compression, at some specific point and along a specific direction x, if the normal component of the stress vector across a surface with normal direction x is directed opposite to x. If the stress vector itself is opposite to x, the material is said to be under normal compression or pure compressive stress along x. In a solid, the amount of compression generally depends on the direction x, and the material may be under compression along some directions but under traction along others. If the stress vector is purely compressive and has the same magnitude for all directions, the material is said to be under isotropic or hydrostatic compression at that point. This is the only type of static compression that liquids and gases can bear.
In a mechanical longitudinal wave, or compression wave, the medium is displaced in the wave's direction, resulting in areas of compression and rarefaction.
Compression, in astronomy is the deviation of a heavenly body from the spherical form, called also the ellipticity. It is numerically expressed by the ratio of the differences of the axes to the major axis of the spheroid. The compression or "flattening" of the earth is about 1/298, which means that the ratio of the equatorial to the polar axis is 298:297
In functional analysis, the compression of a linear operator T on a Hilbert space to a subspace K is the operator
PT| : K → K
,
where P : H → K is the orthogonal projection onto K. This is a natural way to obtain an operator on K from an operator on the whole Hilbert space. If K is an invariant subspace for T, then the compression of T to K is the restricted operator K→K sending k to Tk.
More generally, for a linear operator T on a Hilbert space H and an isometry V on a subspace W of H, define the compression of T to W by
T = VTV : W → W
,
where V is the adjoint of V. If T is a self-adjoint operator, then the compression T is also self-adjoint. When V is replaced by the inclusion map I : W → H, V = I = P : H → W, and we acquire the special definition above.
In geology the term compression refers to a set of stresses directed toward the center of a rock mass. Compressive strength refers to the maximum compressive stress that can be applied to a material before failure occurs. When the maximum compressive stress is in a horizontal orientation, thrust faulting can occur, resulting in the shortening and thickening of that portion of the crust. When the maximum compressive stress is vertical, a section of rock will often fail in normal faults, horizontally extending and vertically thinning a given layer of rock. Compressive stresses can also result in folding of rocks. Because of the large magnitudes of lithostatic stress in tectonic plates, tectonic-scale deformation is always subjected to net compressive stress.
Usage examples of "compression".
Investigations into the relative efficiency of gasoline and denatured alcohol as power producers, undertaken in connection with work for the Navy Department, have demonstrated that with proper manipulation of the carburetters, igniters, degree of compression, etc.
Through the agency of compression one of the testes was forced along the corpus cavernosum under the skin as far as the glans penis.
The boiler feedwater, as had become standard practice, was preheated by being used as the cooling-water for the compression cylinders.
Her buttocks and legs supported him now by their resistance to compression, no longer by an act of will.
The curve, or distortion, of the spine increases more rapidly as the body becomes heavier, the spine often assuming the shape of the letter S, and, from compression by torsion of the vertebrae and distortion of the ribs, the vital organs are encroached upon, causing serious functional derangement of the heart, lungs, liver, and stomach, producing, as its inevitable consequence a list of maladies fearful to contemplate.
Investigation of the internal stresses, which balance the external forces, shows that most of the material should be arranged in a top flange, boom or chord, subjected to compression, and a bottom flange or chord, subjected to tension.
The sudden compression of air as the rammer thrust with the fleece could explode the residues of unburnt powder that was caked to the breech walls, so a gunner, wearing a leather thumbstall, pressed his thumb over the vent to stop the airflow.
The art of healing also has achieved some of its most glorious triumphs in the compressions, extensions, trepannings, colligations, and other surgical or diaetetic operations by which Irregularity has been partly or wholly cured.
Space Force code-talk, and lots of transmissions in the particular squeak of scrambled, enciphered, and high-speed compression signals were suddenly coming from the scanners.
PPP commands such as authentication, multilink, compression, callback etc.
If the brain is to interpret images arriving at the retina of the eye, these pathways, with their compressions and expansions, have to be organized in an orderly manner - and indeed it can be shown that there is a precise topographic mapping of the retina onto the neurons of the lateral geniculate and a further mapping of these cells onto those of the visual cortex.
Cold water was pumped down each umbilical by peristaltic compression waves, heated by being circulated in the superheated thermal environment of the underwater volcanoes, and then pumped back to the surface.
Fearing the possible consequences of such compression to the intellectual organs, he even went so far as to say to her, "Do you want to make Caribs or Botocudos of them?
She was swimming out through layers of life, and she sensed the subtle sounds of living things washing through the sphere: the smooth rush of the fish as they swam in their tight schools, the bubbling murmur of the krill on which they browsed, the hiss of the diatoms and algae that fed them, and the deep infrasonic rumble of the water itself, compression waves pulsing through its bulk.
As the portage of our canoes over this high rock would be impossible with our strength, and the only danger in passing through those narrows was the whorls and swells arising from the compression of the water.