| 释义 |
neper
neper (ˈneɪpə; ˈniː-) n (Units) a unit expressing the ratio of two quantities, esp amplitudes in telecommunications, equal to the natural logarithm of the ratio of the two quantities. Symbol: Np or N [C20: named after John Napier; the name was approved in 1928]neper
neper[′nē·pər] (physics) Abbreviated Np. Also known as napier. A unit used for expressing the ratio of two currents, voltages, or analogous quantities; the number of nepers is the natural logarithm of this ratio. A unit used for expressing the ratio of two powers (even when this ratio is not the square of the corresponding current or voltage ratio); the number of nepers is the natural logarithm of the square root of this ratio; to avoid confusion, this usage should be accompanied by a specific statement. Neper a unit used for expressing the ratio of two physical quantities of the same kind, the number of nepers being the natural logarithm of such a ratio. The neper is named after John Napier and abbreviated Np. The neper is defined as follows: 1 Np = In (F2 / F1) if F2 / F1 = e, where F2 and F1 are physical “force” quantities, for example, voltages, current strengths, and pressures, and e is the base of the natural system of logarithms. Nepers are used mainly for measuring attenuation (damping) of electric signals in communication lines. A neper is related to other logarithmic ratios by the following formulas: 1 Np = 2 log e bel ≈ 0.8686 bel = 8.686 decibels. neperThe unit of measurement based on Napierian logarithms that represents the ratio between two values, such as current or voltage.neper
ne·per (Np), (ne'pĕr), A unit for comparing the magnitude of two powers, usually in electricity or acoustics; it is one half of the natural logarithm of the ratio of the two powers. Synonym(s): napier [fr. neperus, latinized form of (John) Napier] ne·per (nē'pĕr) A unit for comparing the magnitude of two powers, usually in electricity or acoustics; it is one half of the natural logarithm of the ratio of the two powers. [fr. neperus, latinized form of (John) Napier]neper (nē′pĕr, nā′) [John Napier, Scot. mathematician, 1550–1617] , NpA unit of measure denoting the ratio of two amplitudes. It is similar to the decibel but is expressed as a natural logarithm instead of a logarithm of the base 10. 1 Np = 8.687 dB. AcronymsSeeNPThesaurusSeeNapier |