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orbital resonance bâzâvâyi-ye madâri Fr.: résonance orbitale The situation in which two orbiting objects exert a regular, periodic gravitational influence on each other and therefore their orbital frequencies are related by a ratio of two small → integers. Orbital resonance often results in an unstable interaction in which bodies exchange momentum and shift orbits until the resonance disappears. The resonance increases the eccentricity until a body approaches a planet too closely and the body is slung away. |
orbital shrinkage darhamkešidegi-ye madâri Fr.: rétrécissement de l'orbite The lessening in size of the orbit of a binary system composed of two compact objects (pulsars/black holes) due to loss of energy by the system, in particular through gravitational wave radiation. This loss will cause the two objects to approach closer to each other, the orbital period decreases and the binary companions will eventually merge. → orbital; shrinkage, from shrink, from M.E. schrinken, O.E. scrincan, from P.Gmc. *skrenkanan (cf. M.Du. schrinken, Swed. skrynka "to shrink." Darhamkešidegi "shrinking, shriveling," from state noun of < i>darhamkešidé, from darham- "together, in eachother, toward eachother" (For etymology of dar-, → in-; for etymology of ham-, → com-) + kešidé "drawn, shrivelled, wrinkled," from Mod./Mid.Pers. kešidan, kašidan "to draw, protract, trail, drag, carry," dialectal Yaqnavi xaš "to draw," Qomi xaš "streak, stria, mark," Lori kerr "line;" Av. karš- "to draw; to plow," karša- "furrow;" Proto-Iranian *kerš-/*xrah- "to draw, plow;" cf. Skt. kars-, kársati "to pull, drag, plow;" Gk. pelo, pelomai "to move, to bustle;" PIE base k^{w}els- "to plow;" madâri, → orbital. |
orbital speed tondâ-ye madâri Fr.: vitesse orbitale Same as → orbital velocity. |
orbital velocity tondâ-ye madâri Fr.: vitesse orbitale The velocity of an object in a given orbit around a gravitating mass. For a perfect circular orbit, the velocity is described by the formula V =√[G(M + m)/r], where G is the gravitational constant, M the mass of the primary gravitating body, m the mass of the orbiting object, and r the radius of the orbit. |
orbitography madârnegâri Fr.: orbitographie In astronautics, the study of satellite orbits and precise determination of orbital elements which gives the exact position of the satellite. |
order 1) râyé; 2) râyândan Fr.: 1) ordre; 2) ordonner 1a) General: The way in which several items are arranged, as an indication
of their relative importance or size or when each will be dealt with. From O.Fr. ordre, from earlier ordene, from L. ordinem (nominative ordo) "row, rank, arrangement." Râyé, noun related to râyânidan "to regulate, set in order," from Mid.Pers. râyânīdan "to arrange, organize," from rây- (Mod.Pers. ârây-, ârâyeš, ârâyidan "to arrange, adorn"), ârây-, ârâstan "to arrange, adorn;" O.Pers. rād- "to prepare," rās- "to be right, straight, true," rāsta- "straight, true" (Mod.Pers. râst "straight, true"); Av. rāz- "to direct, put in line, set," razan- "order;" Gk. oregein "to stretch out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" Skt. rji- "to make straight or right, arrange, decorate;" PIE base *reg- "move in a straight line;" see also → direct. |
order of a graph râye-ye negâré Fr.: ordre de graphe |
order of a tensor râye-ye tânsor Fr.: ordre de tenseur The maximum number of the indices (→ index) of a tensor. |
order of interference râye-ye andarzaneš Fr.: ordre d'interfrérence A whole number which characterizes a particular position of an interference fringe according to whether there is interference arising from one, two, three, etc. wavelength difference of path. Same as → interference order → order; → interference. |
order of magnitude râye-ye borz Fr.: ordre de grandeur Value of a number or of a physical quantity given roughly, usually expressed as a power of 10. Thus, 2.5 x 10^{5} and 6.4 x 10^{5} are of the same order of magnitude, and 2 x 10^{7} is 2 orders of magnitude greater than either. |
ordered bârâyé, râyedâr Fr.: ordonné Characterized by → order; arranged according to a rule. → ordered tree. → order + -ed. |
ordered tree deraxt-e bârâyé Fr.: arbre ordonné In → graph theory, a → tree in which the → children of each → vertex are ordered. |
ordinal râye-yi Fr.: ordinal 1) Of or relating to an order, as of animals or plants. M.E., from O.Fr., from L.L. ordinalis "denoting order or place in a series," from L. ordo (genitive ordinis) "row, series," → order; → -al. |
ordinal number adad-e râye-yi Fr.: nombre ordinal 1) A number which defines the position or rank of something in a series, in contrast to
→ cardinal number. For example, first,
second, tenth, etc. |
ordinary šunik Fr.: ordinaire Usual; normal. → ordinary ray; → ordinary year. M.E. ordinarie, from O.Fr. ordinarie, from L. ordinarius "regular, usual, orderly," from ordo (genitive ordinis) "order" + -arius-ary. Šunik "ordinary," from Mid.Pers. šônik, šônig "ordinary, customary," from šôn "kind, manner, sort, way" + -ik, → -ic. |
ordinary differential equation hamugeš-e degarsâneyi-ye šunik Fr.: équation différentielle ordinaire A → differential equation in which the unknown function depends on only one → independent variable, as contrasted with a → partial differential equation. → ordinary; → differential; → equation. |
ordinary point noqte-ye šunik Fr.: point ordinaire The point M_{0}(x_{0},y_{0}) of the curve F(x,y) = 0, where at least one of the partial derivatives ∂F/∂x and ∂F/∂y does not vanish. → singular point |
ordinary ray partov-e šunik Fr.: rayon ordinaire The ray that has an → isotropic speed in a → doubly refracting crystal. It obeys → Snell's law upon refraction at the crystal surface. See also → extraordinary ray |
ordinary year sâl-e šunik Fr.: année ordinaire A → calendar year that contains 365 days and therefore is not a → leap year. |
ordinate ârâ (#) Fr.: ordonnée Math.: In plane Cartesian coordinates, the distance of a point from the x-axis measured parallel to the y-axis. → abscissa. Ordinate, from N.L. (linea) ordinate (applicata) "(line applied) in order;" from ordinatus "arranged." Ârâ, from ârâstan "to arrange, to set in order, adorn," Mid.Pers. ârây-, ârâstan "to arrange, adorn;" O.Pers. rās- "to be right, straight, true," rāsta- "straight, true" (Mod.Pers. râst "straight, true"), rād- "to prepare;" Av. rāz- "to direct, put in line, set," razan- "order;" Gk. oregein "to stretch out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" Skt. rji- "to make straight or right, arrange, decorate;" PIE base *reg- "move in a straight line." |
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