| 释义 |
compression|kəmˈprɛʃən|
Also 5–6 comprysion, -prission.
[a. F. compression, ad. L. compressiōn-em, n. of action, f. comprimĕre (ppl. stem compress-): see compress v.]
1. a. The action of compressing; pressing together, squeezing; forcing into a smaller compass; condensation by pressure.
c1400Lanfranc's Cirurg. (MS. A) 23 A gristil..haþ sixe helpingis [uses]..þo .ij. þat þe harde schulde not hirte þe neische, nameli in þe tyme of compressioun [v.r. comprission], & in þe tyme of smytinge. 1597Lowe Chirurg. (1634) 58 Cast forth by the great dilation of the heart or else by the great comprysion thereof. 1599Soliman & P. i. in Hazl. Dodsley V. 289 Why, what is jewels, or what is gold, but earth; An humour knit together by compression. 1659J. Leak Water-wks. Pref. 3 Water cannot be forced by compression to be contained in less space then its Natural extension. 1774Goldsm. Nat. Hist. (1776) II. 59 The infant itself has milk in its own breasts, which may be squeezed out by compression. 1863Tyndall Heat i. §7 (1870) 6 To consider the development of heat by compression.
b. Constraint, coercion.
1880Ch. Times 10 Nov. 779 Dwelling chiefly upon the causes of modern infidelity in France, [he] does not hesitate to ascribe it in a great measure to the compression exercised by Louis XIV.
c. fig. The condensation of thought or language.
1820Miss Mitford in L'Estrange Life (1870) II. v. 92 Great as our merits might be in some points, we none of us excelled in compression. 1850A. Jameson Leg. Monast. Ord. Pref. (1863) 15 The difficulty of compression has been the greatest of all my difficulties.
d. In a steam-engine, the reduction in volume of the steam left in the cylinder after the exhaust is closed towards the end of the exhaust stroke.
1859W. J. M. Rankine Man. Steam Eng. iii. iii. 420 Compression, or cushioning, is effected by closing the eduction valve before the end of the return stroke. 1913W. R. King Steam Engin. v. 105 This compression provides an elastic cushion of steam which absorbs the momentum of the reciprocating parts of the engine and brings them to rest without shock. 1936E. A. Phillipson Steam Locom. Design x. 317 The compression point should advance when the engine is running..at high piston speeds, in order that sufficient cushioning may be available to counteract the greatly augmented inertia forces then set up by the reciprocating masses.
e. In an internal-combustion engine, the reduction in volume of the mixture of fuel and air drawn into the cylinder; also, the value or effectiveness of this as a factor affecting the running of the engine.
1887D. Clerk Gas Engine vii. 197 When compression is completed the igniting valve acts and the explosion impels the piston. 1907R. B. Whitman Motor-Car Princ. xi. 193 Other losses of compression may be due to a cracked piston. 1912Motor Manual 227 No engine ever pulled well with feeble compression. 1963D. V. W. Francis Morris Engines i. 7 It should be possible to feel a good and even compression for all the cylinders.
2. a. A state or condition of being compressed.
1603Florio Montaigne i. xx. (1632) 43 Those instruments..have their proper compressions and dilatations, etc. 1771Mackenzie Man of Feel. (1886) 37 His fingers lost their compression. 1849Murchison Siluria ix. 204 Every variety of distortion and compression. 1871Tyndall Fragm. Sc. (ed. 6) I. ix. 300 The moraine is in a state of longitudinal compression.
b. of thought, language, or writing.
1759Johnson Idler No. 70 ⁋4 Best pleased with involution of argument, and compression of thought. 1823J. Badcock Dom. Amusem. p. vi, The state of compression in which it [the treatise] now appears.
c. fig. Straitened or repressed condition, under the operation of trouble, tyranny, or the like.
1762Miller tr. Duhamel's Husb. ii. ii. (ed. 2) 190 The state of compression which those in the common way were in after harvest. 1816T. Jefferson Writ. (1830) IV. 280 That nation is too high-minded..to remain quiet under its present compression. 1879Farrar St. Paul (1883) 523 That previous letter..had been written in much tribulation and compression of heart.
3. compression of the poles: the flattening of a planet at the poles, making it an oblate spheroid.
1816Playfair Nat. Phil. II. 179 The compression of Jupiter amounts to a fourteenth part of his longer diameter. 1849M. Somerville Connect. Phys. Sc. iv. 34 Of ascertaining the compression of Jupiter's spheroid.
†4. Surg.
a. A compress. Obs. rare.
1599A. M. tr. Gabelhouer's Bk. Physicke 110/1 We must also have for the same intente, Compressions, or little pillowes of inveterate linnen.
b. Short for ‘compression of the brain’.
1847South tr. Chelius' Surg. I. 410 It is often very difficult to distinguish between drunkenness and either concussion or compression. 1870T. Holmes Surg. (ed 2) II. 257 In well-marked compression, however, the patient is generally perfectly insensible.
5. attrib. and Comb., as compression bellows, compression chamber, compression gauge, compression machine, compression spring, compression treatment; compression-casting, a method of casting bronzes, etc., in which the metal is forced by compression into the finer tracery of the mould; compression-cock, a tap having a collapsible india-rubber tube; compression-ignition engine, an internal-combustion engine in which the compression of air in the cylinder provides heat to ignite the fuel, as in a Diesel engine; hence compression-ignition, this principle or process; compression mould, a mould which encompasses the material to be shaped (see quot. 1951); compression moulding, a method of moulding plastics by applying pressure; also, the equipment for carrying out this process; a product of this process; compression ratio, the ratio of the maximum to the minimum volume in the cylinder of an internal-combustion engine, measured before and after compression (one piston stroke); compression rib (see quot.); compression stroke, the stroke of the piston effecting the compression of the gas and air in the cylinder of an engine; compression wood, a type of wood that develops on the undersides of branches and at the bases of leaning trunks of softwood trees.
1852Seidel Organ 26 Kaufmann, of Dresden..invented the so-called compression-bellows.
1874Knight Dict. Mech. I. 603/1 The compression-chamber receives its successive charges of air from the atmosphere by valves opening inward.
1912Motor Man. 234 Each cylinder fails to show a high reading on a compression gauge. 1926Engineering 27 Aug. 277/2 A compression-ignition engine with its high expansion ratio may be expected to consume a smaller weight of fuel per horse-power than a petrol engine. 1933Jrnl. R. Aeronaut. Soc. XXXVII. 455 Knock under certain conditions of operation of compression ignition engines may be due to vaporisation of fuel oil during the delay period. 1936Economist 2 May 234/1 The diesel, or compression-ignition, engine requires no preliminary heating. Ibid., ‘Compression-ignition’, with a smaller space in front of the engine piston, produced an increase in ‘thermal efficiency’.
1874Knight Dict. Mech. I. 603/1 The power of such a compression machine.
1951Gloss. Terms Plastics (B.S.I.) 35 Compression mould, a mould which requires to be opened to receive the charge and which forms the material to shape on closing.
1940Chambers's Techn. Dict. 186/1 Compression moulding. The material is placed in a hardened, ground, polished steel container and forced down by means of a plunger at a pressure of 3000–5000 lb. per sq. in. 1958Spectator 25 July 150/3 It also manufactures signalling equipment, compression moulding, electrical components.
1907F. Strickland Man. Petol Motors i. iii. 20 The actual compression ratio to be used in an engine is one of the most important points in its design. 1934Jrnl. R. Aeronaut. Soc. XXXVIII. 44 About 13½:1 is more usual with the open combustion chamber, but with the ‘swirl’ type which he had descibed,..the higher compression ratio was possible. 1958Times 1 July 6/6 It differs from the saloon engine, however, in having a compression ratio of seven to one.
1918Farrow Dict. Mil. Terms, Compression Rib, in an aëroplane, a rib that acts as an ordinary rib, besides bearing the stress of compression produced by the tension of the internal bracing wires.
1904A. B. F. Young Compl. Motorist iv. 82 The steering on the car is of an exceedingly strong character... Very strong and stiff compression springs effectually prevent any possibility of ‘backlash’.
1894B. Donkin Gas, Oil, & Air Engines i. vii. 90 The compression stroke forces this residuum and part of the fresh charge up the narrow passage leading to the hot tube, and causes ignition. 1908Westm. Gaz. 22 Oct. 4/3 The compression-stroke, in which the piston, by its upward motion compresses the charge of gas into the head of the cylinder. 1912Motor Man. 237 The power is developed during a complete cycle of four strokes..one occurring at each half revolution or every stroke of the piston; thus (1) suction stroke, (2) compression stroke [etc.].
1925Spiral Tracheids & Fiber-Tracheids: Tropical Woods (Yale Univ. Sch. of Forestry) 12 In so-called compression wood or ‘red’ wood (rotholz), found in both the Angiospermae and Gymnospermae, the cells have a thick laminated secondary wall, slit into a large number of closely compressed spiral lamellae. 1940Chambers's Techn. Dict. 186/1 Compression wood.
Add: [c indigo][1.] f.[/c] Electronics and Telecommunications. The reduction of the variability of a signal; spec. the introduction of a variable gain factor in such a way as to reduce the range over which the signal amplitude varies.
1938G. E. Sterling Radio Manual (ed. 3) iv. 124 Even weak speech-sounds can be made to over-ride noise..without overloading the transmitter on the sounds which are (before compression) strong. 1943F. E. Terman Radio Engineers' Handbk. v. 412 Expanders are used to counteract the compression of volume range that is necessary in sound recording. 1986W. Sinnema Digital, Analog, & Data Communication (ed. 2) iii. 139 Compression is applied to the signal to slightly reduce the maximum signal amplitudes and significantly raise the minimum signal amplitudes.
g. Computing. [tr. Russ. svertȳvanie; first used in Russ. in this sense by L. N. Korolev 1957, in Dokladȳ Akad. Nauk SSSR CXIII. 746.] The process of reducing the amount of space occupied by data that is being stored or transmitted, by minimizing redundant information.
1957tr. L. N. Korolev in Doklady Acad. Sci. U.S.S.R. CXIII. 724 (title) Coding and compression of codes. 1966Datamation Apr. 39/1 Data compression eliminates redundant data and retains useful data. 1987S. Brand Media Lab i. v. 81 Analogy is a wonderful way to think of semantic data compression: this signal is like that signal, and you got that signal already. 1991Personal Computer World Feb. 20/2 The MNP level-5 error correction and compression offers up to 80{pcnt} additional throughput. |