Fr.: densité de flux
Flux of radiation that falls on a detector per unit surface area of the detector per unit bandwidth of the radiation per unit time.
Fr.: unité de flux
In radio astronomy, same as → jansky (symbol Jy), a unit of electromagnetic flux equivalent to 10-26 watts per square meter per Hertz.
In Newton's work on → calculus, the rate of change of a fluent (i.e. a flowing quantity), today commonly known as → variable. For a fluent x, the fluxion is denoted dx/dt. An obsolete mathematical term.
parvâz kardan (#), parvâzidan (#)
To move through the air using wings. Travel through the air or outer space.
M.E. flien, O.E. fleogan; cognate with O.H.G. fliogan, Ger. fliegen, O.Norse fljuga.
Infinitive from parvâz, → flight.
A trajectory that takes a → space probe close to a Solar System body (planet, satellite, asteroid, comet) but does not permit it to enter an orbit about the body.
→ fly + by, from M.E., from O.E. be or bi, from P.Gmc. *bi "around, about" (cf. Du. bij, Ger. bei "by, at, near"), from *umbi, (cf. L. ambi "around, about," Gk. amphi "around, about," Skt. abhi "on both sides," Av. aibi, aiwi, O.Pers. aiby "to, against, in addition to," Mid.Pers. aw-, ab-, Mod.Pers. af- (as in afzudan "to increase, add," afruxtan "to inflame, kindle, blaze," afqân "lamentation, groaning, cires for help").
Of or relating to a focus; placed at or measured from a focus.
Fr.: distance focale
same as → focal length.
Fr.: longueur focale
The distance between the optical center of a lens, or the surface of a mirror, and its focus.
Fr.: plan focal
A plane at right angles to the principal axis of a lens or mirror on which the best image is formed.
Fr.: point focal
Same as → focus.
Fr.: rapport focal
The ratio of the → focal length of a reflecting surface or lens to its effective diameter, i.e. to its → aperture. The smaller the focal ratio, the smaller the image scale and the more luminous the image for a given aperture.
kâhande-ye kânuni, bâzhâzande-ye ~
Fr.: réducteur focal
1) kânun; 2) kânunidan
Fr.: 1) foyer; 2) focaliser
1) (n.) A point where parallel light rays from an object are gathered together by a
lens or a concave mirror. It is the place where the clearest image of a distant object
forms. Also called focal point. See also → focal distance.
From L. focus "hearth, fireplace," of unknown origin,
Kânun "hearth, fireplace."
Of an optical system, being in focus or brought into focus; adjusted to produce a clear image.
Past participle of → focus.
The act of bringing into focus.
Noun of → focus.
A mass or layer of suspended water droplets or ice crystals near the surface of the earth, reducing visibility.
From Dan. fog "spray, shower, snowdrift," related to O.N. fok "snow flurry."
Meh "fog" (variants miq, mož, Tabari miyâ, Lori/Laki (kara) mozy, Ossetic mig/megæ), from Mid.Pers. mēq "cloud, mist," Av. mēγa- "cloud;" cf. Skt. meghá- "cloud, overcast weather;" Gk. omikhle "mist;" Lith. miglà "mist, haze;" PIE base *mighlā- "cloud."
Fr.: arc blanc
A large, faintly colored, circular arc formed by light (usually sunlight) falling on cloud or fog. Also called → cloudbow.
Fr.: équation de Fokker-Planck
A modified form of → Boltzmann's equation allowing for collision terms in an approximate way. It describes the rate of change of a particle's velocity as a result of small-angle collisional deflections.
After Dutch physicist Adriaan Fokker (1887-1972) and the German physicist Max Planck (1858-1947); → equation.
Fr.: gens, les gens
1) Usually, folks. (used with a plural verb) people in general.
M.E.; O.E. folc; cognate with O.Sax., O.Norse folk, O.H.G. folk (Ger. Volk).
Palg, from (Pashto) parrk "group of people," with variants: (Dehxodâ) parré "group of people; a circular disposition of troops for hunting or other purposes; a rank or file of soldiers;" (Lori, Torbart-Heydariye-yi, Qomi) borr "group of people, crowd;" (Qomi) borré; (Laki) berr "group of people;" (Qâyeni) bor "group, flock, herd;" (Kurd. Kurmanji) âpora "crowd;" transformation of -r- into -l- (as por = bol, → poly-) in Tabari bəlik, əllik "herd, flock;" ultimately from Proto-Ir. *paraka-, from *par- "to fill;" cf. Av. pər- "to fill, stuff with," pouru- "full, much, many;" O.Pers. paru- "much, many;" Pers. anbâr "ricks, storehouse," por, bol "full, much, many;" PIE *pel- "to fill;" → population.
The traditional beliefs, legends, customs, etc., of a people; lore of a people (Dictionary.com).
Coined by English scholar and antiquary William John Thoms (1803-1885), from → folk, + lore "traditional knowledge or belief," from M.E., O.E. lar cognate with Du. leer, Ger. Lehre "teaching," E. learn.
Palgvâr, literally "customs of people," from palg, → folk, + vâr "custom, rule, law" (Dehxodâ).