| 释义 |
synchronous, a. Chiefly scientific and technical.|ˈsɪŋkrənəs|
[f. late L. synchronus, a. Gr. σύγχρονος, f. σύν syn-1 + χρόνος time: see -ous.]
1. a. Existing or happening at the same time; coincident in time; belonging to the same period, or occurring at the same moment, of time; contemporary; simultaneous. Const. with.
1669Gale Crt. Gentiles i. ii. v. 56 Hercules, the Tyrian Commander; whom some make synchronous with Moses. 1772Nugent Hist. Fr. Gerund I. 217 It is affirmed by a coetaneous, syncronous, and faith-worthy author. 1833Lyell Princ. Geol. III. 42 Formations, which, although dissimilar both in organic and mineral characters, were of synchronous origin. 1872Nicholson Palæont. 19 Synchronous deposits necessarily contain wholly different fossils, if one has been deposited by fresh water, and the other has been laid down in the sea. 1878Bates Centr. Amer. vi. 78 The rainy season on the coasts is not synchronous with that of the uplands.
b. transf. Relating to or treating of different events or things belonging to the same time or period; involving or indicating contemporaneous or simultaneous occurrence.
1823Thomasina Ross Bouterwek's Hist. Sp. Lit. I. 499 A synchronous account of all the remarkable productions of the polite literature of Spain. 1843Civil Eng. & Arch. Jrnl. VI. 159/2 Where is the line to be drawn by which different styles ought to have been set apart as worthy to afford a new starting point for synchronous treatment? 1882–3Schaff's Encycl. Relig. Knowl. 1249 The synchronous history of the divided kingdoms of Israel and Judah.
c. synchronous curve (Geom.), a curve which is the locus of the points reached at any instant by a number of particles descending from the same point down a family of curves under the action of gravity.
1867Brande & Cox Dict. Sci., etc.
2. a. Recurring at the same successive instants of time; keeping time with; going on at the same rate and exactly together; having coincident periods, as two sets of vibrations or the like. Cf. sense 2 d below.
1677F. North Philos. Ess. Mus. 20 The synchronous motion of the pulses at the mouth of the Pipe with the vibrations of the included Air promote the Sound of the Pipe. 1733Arbuthnot Ess. Air (J.), The variations of the gravity of the air keep both the solids and fluids in an oscillatory motion, synchronous and proportional to their changes. 1786J. Pearson in Med. Commun. II. 98 Pulsation.., synchronous with that of the radial artery. 1866Duke of Argyll Reign of Law iii. (1867) 173 The beats of a bird's two wings are always exactly synchronous. 1871Tyndall Fragm. Sci. (1879) I. xiv. 391 Affected by those undulations which are synchronous with their own periods of vibration. 1899Allbutt's Syst. Med. VIII. 42 The spasms of the face and those of the palate were not synchronous. 1972Sci. Amer. Apr. 45/1 In all cases where this effect is significant these same tides will have ‘despun’ the satellite to synchronous rotation, that is, the satellite's period of rotation around its own axis equals its period of revolution around the planet and it always presents one face to the planet.
b. Electr. Applied to alternating currents having coincident periods; also to a machine or motor working in time with the alternations of current.
1897A. Hay Princ. Alternate-Current Working vi. 88 By a synchronous motor is meant one whose speed bears a definite ratio to the periodicity of the alternating current. 1901A. Russell in Electr. Rev. 19 July 88/1 The Power Factor of a Synchronous Motor. 1920Whittaker's Electr. Engineer's Pocket-bk. (ed. 4) 219 If..the converter is in parallel with other synchronous machinery. 1930Engineering 25 Apr. 534/3 (heading) Hydrogen-cooled synchronous condenser. 1962J. Bell in G. A. T. Burdett Automatic Control Handbk. iv. 7 Torque synchros or synchronous links (Magslips).
¶ erron. Of uniform velocity.
1785Reid Intell. Powers ii. iv. 253 That relation of synchronous vibrations which produces harmony.
c. Computers and Telecommunications. Of apparatus or methods of working: making use of equally spaced pulses that govern the timing of operations.
[1947A. W. Burks et al. in J. Von Neumann Coll. Wks. (1963) V. 68 Since the timing of the entire computer is governed by a single pulse source, the computer circuits will be said to operate as a synchronized system.] 1954Trans. IRE Prof. Group Electronic Computers June 14/2 Because the system being designed was centrally synchronous, over-all timing considerations now came to the fore. 1962Y. Chu Digital Computer Design Fundamentals v. 161 The binary state of the signals in logic circuits can be represented by either of two voltage levels or by pulses... A synchronous computer also requires clock pulses. 1971I. H. Gould IFIP Guide Concepts & Terms Data Processing 76 Synchronous working and asynchronous working often coexist in different parts of a computer system. For example, in many computers the central processor is synchronous, but the operation of peripheral equipment is only initiated by signals from the central processor and thereafter proceeds asynchronously. 1982Heap & Martin Introd. Digital Electronics iii. 73 In the worst case the problem of interfacing two independent synchronous systems which are operating at different clock rates may occur.
d. Of a satellite: rotating round the parent planet at the same rate as the planet rotates. Of an orbit: such that a satellite in it is synchronous.
1961N.Y. Times 30 July iv. 9/8 Synchronous satellites will require bigger boosters to reach their higher altitudes. 1964Daily Tel. 4 Mar. 14/6 Three satellites in this synchronous orbit would give a complete global system of communications except for small regions round the North and South Pole. 1967Technology Week 20 Feb. 4/2 There is substantial agreement that a synchronous satellite is desirable for air traffic control. 1970Nature 9 May 503/1 Only one orbit exists which is at the same time equatorial, circular and synchronous. 1978Daily Tel. 11 July 2/5 ‘Charon’, which brings to 33 the number of known moons in the solar system, appears to have a synchronous orbit around Pluto of 12,000 miles, which means that it always stays over a fixed spot over Pluto.
3. Linguistics. = synchronic a. 3.
1936[see diachronous a. 2]. |