| 释义 |
Heaviside Physics.|ˈhɛvɪsaɪd|
The name of O. Heaviside (1850–1925), English physicist, used attrib. to designate concepts proposed by him; esp. Heaviside layer, an ionized layer in the upper atmosphere able to reflect long radio waves (now usu. called E layer of the ionosphere); Heaviside–Lorentz 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 Electr. Communication.
1911Encycl. Brit. XXVII. 744/2 It will be seen..that the Heaviside rational units are all incommeasurable with the practical units. 1912Proc. R. Soc. A. LXXXVII. 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. 1913Year-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. 1926R. W. Hutchinson 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. 1937Discovery Mar. 65/2 The well known Heaviside and Appleton layers which play such an important part in carrying broadcasting to long distances. 1940Chambers's Techn. Dict. 407/2 Heaviside unit function, a step in which the change in amplitude is unity. 1955O. Klein in W. Pauli N. Bohr 99 The units are the usual ones, ℏ = c = 1 and Heaviside–Lorentz units for the electromagnetic quantities. 1963Jerrard & 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. |