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单词 heaviside
释义

Heavisiden.

Brit. /ˈhɛvɪsʌɪd/, U.S. /ˈhɛviˌsaɪd/
Etymology: < the name of O. Heaviside (1850–1925), English physicist.
Physics.
Used attributively to designate concepts proposed by Heaviside; esp. Heaviside layer, an ionized layer in the upper atmosphere able to reflect long radio waves (now usually called E layer of the ionosphere); HeavisideLorentz units (H. A. Lorentz, 1853–1928, Dutch physicist), or Heaviside rational units, units of electric charge or magnetic pole defined in a certain manner which simplifies many formulæ; Heaviside unit function, a function which is zero when its argument is negative, and unity when its argument is positive; used esp. in Telecommunications.
ΘΚΠ
the world > the earth > weather and the atmosphere > [noun] > specific regions of > specific regions of ionosphere
Heaviside layer1911
F-region1928
D-region1930
E-region1930
sporadic E-layer1937
ledge1949
protonosphere1960
topside1962
the world > matter > physics > electromagnetic radiation > radio wave > [noun] > layer reflecting long or waves
Heaviside layer1911
E-layer1930
sporadic E1937
sporadic E-layer1937
the world > matter > physics > electromagnetic radiation > electricity > electric charge, electricity > [noun] > unit of measurement > rationalized
Heaviside rational units1911
Heaviside–Lorentz units1955
1911 Encycl. Brit. XXVII. 744/2 It will be seen..that the Heaviside rational units are all incommeasurable with the practical units.
1912 Proc. Royal Soc. A. 87 95 Both long and short waves are propagated through the lower and middle atmosphere in straight lines to great heights and reflected at the Heaviside layer.
1913 Year-bk. Wireless Telegr. 395 The conductivity, and consequently the reflecting power, of the Heaviside layer depends greatly on the presence of local electro~motive forces.
1926 R. W. Hutchinson First Course Wireless vii. 131 It is clear that if the earth were surrounded by a spherical conductor some distance away from it the waves would travel between this conducting surface and the conducting surface of the earth, and they would follow the curvature of the earth... Such a conductor does exist and it is known as the Heaviside layer.
1937 Discovery Mar. 65/2 The well known Heaviside and Appleton layers which play such an important part in carrying broadcasting to long distances.
1940 Chambers's Techn. Dict. 407/2 Heaviside unit function, a step in which the change in amplitude is unity.
1955 O. Klein in W. Pauli Niels Bohr & Devel. Physics 99 The units are the usual ones, ℏ = c = 1 and Heaviside–Lorentz units for the electromagnetic quantities.
1963 H. G. Jerrard & D. B. McNeill Dict. Sci. Units 14 The Heaviside–Lorentz units were the earliest rationalized units, they were proposed by Heaviside in 1883 and used by him in a classical paper on electrical theory published nine years later.
This entry has not yet been fully updated (first published 1933; most recently modified version published online March 2022).
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