Fr.: hélicité cinétique
In fluid mechanics, a quantity that describes helical flow. It is defined by the integrated scalar product of the velocity field and the → vorticity: KK = ∫ dVu . (∇ x u). In the absence of magnetic field, this quantity is conserved by the → Euler equation. See also → magnetic helicity.
Fr.: potentiel cinétique
Same as → Lagrangian function.
damâ-ye jonbeši (#)
Fr.: température cinétique
The temperature of a gas defined in terms of the average kinetic energy of its atoms or molecules.
kinetic theory of gases
negare-ye jonbeši-ye gâzhâ (#)
Fr.: théorie cinétique des gaz
A theory that explains macroscopic properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion.
Fr.: diagrame de Kippenhahn
A plot representing the evolution of the internal structure of a star as a function of time. The x-axis indicates the time, the y-axis the mass, and a color or shading specifies convective regions. A vertical line through the graph corresponds to a model at a particular time.
Named after Rudolf Kippenhahn (1926-), a German astrophysicist; → diagram
qânun-e Kirchhoff (#)
Fr.: loi de Kirchhoff
The radiation law which states that at thermal equilibrium the ratio of the energy emitted by a body to the energy absorbed by it depends only on the temperature of the body.
Gustav Robert Kirchhoff (1824-1887), a German physicist who made major contributions to the understanding of electric circuits, spectroscopy, and the emission of black-body radiation from heated objects; → law.
gâfhâ-ye Kirkwood (#)
Fr.: lacunes de Kirkwood
Regions in the asteroid belt within which few asteroids are found. The Kirkwood gaps are due to the perturbing effects of Jupiter through resonances with Jupiter's orbital period.
Named for the American astronomer Daniel Kirkwood (1814-1895), who Discovered them in 1866; → gap.
Fr.: nébuleuse de Kleinmann-Law
An strong, extended infrared source in the Orion Nebula, about 1 arcminute NW of the Trapezium and about 12 arcseconds south of the → Becklin-Neugebauer object. It dominates the infrared emission at wavelengths above 20 microns. It probably represents a cluster of young and forming stars embedded in a dusty molecular cloud.
Named after Douglas E. Kleinmann (1942-) and Frank J. Low (1933-), who first studied this object in 1967; → nebula.
Fr.: Klotho, Clotho
A → main belt asteroid (97) discovered by the German astronomer Ernst W. Temple in 1868 working at Marseille Observatory.
Named after Klotho (literally "spinner") the Gk. goddess of fate who spins the thread of life, from klothein "to spin."
An electron tube for converting direct-current energy into radio frequency energy by alternately speeding up and slowing down the electrons. It is used as a microwave amplifier or oscillator in radar and high-frequency radio work.
From Gk. kluzein, klus- "to wash, break over" + -tron.
1) The joint of the leg that allows for movement between the femur and tibia and is
protected by the patella; the central area of the leg between the thigh and the lower leg.
M.E. kne; O.E. cneo, cneow "knee" (cognates: O.Norse kne, O.Sax. kneo, M.Du. cnie, Dutch knie, O.H.G. kniu, Ger. Knie; cf. Pers. zânu, as below.
Zânu "knee," Mid.Pers. šnûg "knee;" Av. žnu- "knee;" cognates: Skt. jānu-, Hittite genu "knee;" Gk. gonu "knee," gonia "corner, angle;" L. genu "knee;" O.E. cneo, as above; PIE *gnéwo-.
1) An instrument for cutting, consisting essentially of a thin,
sharp-edged, metal blade fitted with a handle.
M.E. knif; O.E. cnif, probably from O.N. knifr; cf. M.L.G. knif, M.Du. cnijf, Ger. Kneif; of uncertain origin.
Kârd "knife," from Mid.Pers. kârt "knife;" Av. karət- "to cut;" cf. Skt. kart- "to cut," karəta- "knife;" Proto-Ir. *kart- "to cut."
âzmun-e kârd (#)
Fr.: contrôle par foucaultage
The same as → Foucault knife-edge test.
1) To perceive or understand as fact or truth; to apprehend clearly and with certainty.
M.E. knowen, knawen, from O.E. cnâwan, akin to O.H.G. bichnâan "to recognize," L. gnoscere, noscere "to come to know," Gk. gignoskein, Pers. šenâxtan, dânestan, as below.
Dânestan "to know;" Mid.Pers. dânistan "to know;" variant šenâxtan, šenâs- "to recognize, to know" (Mid.Pers. šnâxtan, šnâs- "to know, recognize"); O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge," cognate with L. gnoscere, noscere "to come to know" (Fr. connaître; Sp. conocer); P.Gmc. *knoeanan; O.E. cnawan, E. know, as above; Rus. znat "to know;" PIE base *gno- "to know."
1) All the information, facts, truths, and principles learned throughout time.
M.E. cnawlece, from O.E. cnawan, cf. O.H.G. bi-chnaan, ir-chnaan "to know;" cognate with Pers. šenâxt, as below.
Šenâxt, past stem of šenâxtan, šenâsidan "to know, discern, distinguish, be acquainted with;" Mid.Pers. šnâxtan, šnâs- "to know, recognize," dânestan "to know;" O.Pers./Av. xšnā- "to know, learn, come to know, recognize;" cf. Skt. jñā- "to recognize, know," jānāti "he knows;" Gk. gignoskein "to know, think, judge;" L. gnoscere, noscere "to come to know" (Fr. connaître; Sp. conocer); O.E. cnawan; E. know; Rus. znat "to know;" PIE base *gno- "to know."
Fr.: couche de Knudsen
Named after Danish physicist Martin Knudsen (1871-1949); → layer.
Kochab (β Ursae Minoris)
The second brightest star in the constellation → Ursa Minor. It is a reddish, evolved → giant of → spectral type K4 with a visual magnitude of 2.1. It is almost 500 times more luminous than the Sun and lies at a distance of 126 light years. Also called Kocab, Kochah.
Kochab, from Ar. al-Kaukab (
pâyâ-ye Kolmogorov (#)
Fr.: constante de Kolmogorov
The proportionality constant C in Kolmogorov's mathematical analysis of → turbulence which states that the spectral energy E(k) in the range of turbulent scales is E(k) =C ε2/3 k-5/3, where k represents the → wave number (inversely proportional to the wavelength or → eddy size), and ε is the average energy dissipation per unit mass in the fluid. Experimental measurements give C close to 1.5.
Andrei Nikolaevich Kolmogorov (1903-1987), a prominent Soviet mathematician, who made major advances in different scientific fields, mainly probability theory, topology, turbulence, classical mechanics, and computational complexity; → constant.
Fr.: échelle de Kolmogorov
Fr.: spectre de Kolmogorov
The distribution of energy over different scales in a → turbulent flow where → energy cascade occurs. Let E be the energy per unit → wave number (k) and ε the energy → dissipation parameter, E = E(k,ε). → Dimensional analysis yields: E = Cε2/3k-5/3, where C is the → Kolmogorov constant.
A. N. Kolmogorov, 1941, Local structure of turbulence in an incompressible fluid for very large Reynolds numbers, Doklady Acad Sci. USSR 31, 301; → spectrum.