| 释义 |
directional, a.|dɪˈrɛkʃənəl|
[f. prec. + -al1.]
†1. Serving for direction or guidance: see quot. Obs.
1612Sturtevant Metallica (1854) 67 Directional is that moddle which is made only to guide the Artificer in the dimensions of all the parts, as also for to direct them for the kinds of the matter and the stuffe..to make the engin intended.
2. Of or relating to direction in space.
1881Maxwell Electr. & Magn. II. 168 These directional relations. 1881Spottiswoode in Nature No. 623. 546 There is a dissymmetry at the two ends or ‘terminals’ of a battery..or other source of electricity, implying a directional character either in that which is transmitted, or in the mode of its transmission.
3. Alg. directional coefficient (of an imaginary quantity), the quotient obtained by dividing the quantity by its modulus.
4. a. Of or pertaining to the direction or guidance of affairs.
1921Glasgow Herald 5 Mar. 6 The responsibility of so improving his directional control of the conditions of working. 1922Ibid. 21 Mar. 7 Their doctrine of one directional authority. 1928Daily Express 26 Sept. 1 All directional and organisation expenses.
b. Of or pertaining to the direction of films, etc.
1949Here & Now (N.Z.) Oct. 29/3 Camera, lighting, directional ‘touches’ are in their subordinate and proper place. 1962Movie Sept. 25/1 The emotional effect of Exodus is the stronger for being free from directional nudges and promptings.
5. Telecommunications. Concerned with the record of directions indicated by radio signals received from a vessel, etc. Also, pertaining or relating to apparatus that transmits or receives radio signals, etc., more strongly in or from certain directions than others.
1914R. Stanley Wireless Telegr. 179 To illustrate the effect of directional aerials at the sender and at the receiver. 1929Bell Syst. Techn. Jrnl. VIII. 313 The use of directional receiving antennas is essential to satisfactory and economic results over such distances as the transatlantic radio path. 1930Aberdeen Press & Jrnl. 26 June 7/1 An occasional directional message from the Cape Race wireless station was the only guidance they could pick up. 1935Economist 30 Nov. 1062/2 Aerial navigation without wireless is to-day almost unthinkable. Night flying has only been made feasible by directional wireless. 1957BBC Handbk. 60 To provide an effective signal in the area served by each programme, highly directional short-wave transmitting aerials are used. Ibid. 219 An efficient type of directional aerial. 1962A. Nisbett Technique Sound Studio 255 The microphone is thus intensely directional.
Hence diˈrectionally adv., with respect to direction.
1879Thomson & Tait Nat. Phil. I. i. §107 A fixed ring in space (directionally fixed, that is to say, but having the same translational motion as the earth's centre). |