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simplex method raveš-e taktâfti Fr.: méthode du simplexe An → algorithm for solving the classical → linear programming problem; developed by George B. Dantzig in 1947. The simplex method is an → iterative method, solving a system of → linear equations in each of its steps, and stopping when either the → optimum is reached, or the solution proves infeasible. The basic method remained pretty much the same over the years, though there were many refinements targeted at improving performance (e.g. using sparse matrix techniques), numerical accuracy and stability, as well as solving special classes of problems, such as mixed-integer programming (Free On-Line Dictionary of Computing, FOLDOC). |
simplification sâde-kard, sâde-šod Fr.: simplification The act of simplifying, or the fact of being simplified. Verbal noun of → simplify. |
simplify sâdé kardan (#) Fr.: simplifier 1) To make less complex or complicated. |
simulacra simulâkrâ Fr.: simulacres Minute images or replicas of objects supposed by ancient atomist philosophers to be shed from any object and used in the explanation of vision. According to Democritus (c. 460-c. 370 BC) and Epicurus (341-270 BC), these replicas or effigies, called eidola, were perpetually peeled off the surfaces of things and caused vision by entering in the eye. L. translation of eidola by Lucretius (1st Century BC), from L. simulacrum "likeness, image," from simulare "to → simulate." |
simulate mânandidan, hamânand sâxtan Fr.: simuler To create a likeness or model of something (a situation, system, or the like). M.E., from L. simulatus, p.p. of simulare "to imitate," from stem of similis "like;" cognate with Pers. ham "together, with; same, equally, even" (Mid.Pers. ham-, like L. com- and Gk. syn- with neither of which it is cognate. O.Pers./Av. ham-, Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-, Gk. homos-; originally identical with PIE numeral *sam- "one," from *som-. The Av. ham- appears in various forms: han- (before gutturals, palatals, dentals) and also hem-, hen-). Mânadidan verb from mânand "resembling, like," variant mânestan "to resemble;" Mid.Pers. mânag "like, resembling;" Av. man- "to resemble;" hamânad sâxtan, from hamânand, from ham-, as above, + mânad + sâxtan "to make, build." |
simulation mânandeš, hamânand sâzi Fr.: simulation The construction of a mathematical model to reproduce the characteristics of a phenomenon, system, or process, often using a computer, in order to infer information or solve problems. Verbal noun of → simulate. |
simultaneity hamzamâni (#) Fr.: simultanéité The property of events occurring → simultaneously. Noun from → simultaneous; → -ity. |
simultaneous hamzamân (#) Fr.: simultané 1) General: Happening, existing, or operating at the same time. From L.L. simultaneus, from L. simul "at the same time" + -taneous, abstracted from → spontaneous. |
sine sinus (#) Fr.: sinus In trigonometry, the function of an acute angle of a right triangle represented by the ratio of the opposite side to the hypotenuse. Greek mathematicians were not aware of the advantages of sine and instead used chord.
The invention of this function is a great Indian contribution. It seems that Aryabhata (c. AD 500)
was the first who coined a term in Skt. for this concept: árdha-jiyā-
"half chord," which was later shortened to
jiyā- "chord." This Skt. word was subsequently loaned in Ar. and corrupted to
jayb ( Sinus loanword from Fr., as above. |
sine wave mowj-e sinusi (#) Fr.: onde sinusoïdale A periodic oscillation that is defined by the function y = sin x. |
single tak, taktâ Fr.: seul, isolé Only one in number; one only; unique; sole. M.E., from O.Fr. sengle "being one, separate," from L. singulus "one, individual, separate," from sim- (stem of simplus) + diminutive suffix, → -ule. Tak"single, alone," related to tâq "odd, single," tâ, tâh "piece, part; fold, plait, ply;" Mid.Pers. tak "single," tâg, tâk, tâi "unit, piece." |
single scattering parâkaneš-e tak Fr.: diffusion unique, ~ simple A type of scattering where photons are scattered only once. Single scattering dominates in → optically thin media, since photons have a high probability of exiting the medium (e.g., a thin cloud) before being scattered again. → single; → scattering. |
single-dish observation nepâhešè-e tak-jâm Fr.: observation avec antenne uinique A radio astronomical observation which uses only one antenna, in contrast to interferometric observations. → single; → dish; → observation. |
single-lined binary dorin-e tak-xatté Fr.: binaire à une seule raie A → spectroscopic binary in which only one set of → spectral lines is detectable. The binary nature of the system is deduced from the fact that the spectral lines exhibit periodic → Doppler shifts due to orbital motions in the system. Same as → SB1 binary. See also: → double-lined binary. |
singlet taktâyé Fr.: singulet A single unit; an unpaired or separate item. → doublet; → octet; → quadruplet. From → single + -et diminutive suffix, M.E. from O.F. -et (masc.), -ette (fem.). Taktâyé, literally "single-folded," from tak, → single, + -tâyé, from tâ- "fold, plait, ply; piece, part;" Mid.Pers. tâg "piece, part" + -yé nuance suffix. |
singlet state hâlat-e taktâyé Fr.: état singulet In atomic physics, the electronic state of an atom or molecule for which the total → spin angular momentum is zero. |
singly ionized atom atom-e yekbâr yonidé Fr.: atome une fois ionisé An atom that has lost one electron and has become a positive ion. |
singly ionized carbon Fr.: carbone une fois ionié A carbon atom → singly ionized by a photon of energy 11.3 eV. The ion C^{+} emits a → fine-structure line (^{2}P_{3/2}→ ^{2}P_{1/2}) at 157.7 μm when excitation conditions are satisfied (critical density ~ 3 x 10^{3} cm^{-3}). In → photodissociation regions, [C II] 157.7 μm is a major cooling line for regions exposed to significant → far ultraviolet (FUV) photon fluxes. In Galactic → H II regions, as well as in the central regions of external galaxies, the luminosity of the [C II] line is typically ~ 0.05-0.5% of the FUV luminosity and correlates well with → carbon monoxide (CO) line intensities. |
singular takin (#) Fr.: singulier Math.: 1) Of or pertaining to a linear transformation from a vector space
to itself that is not one-to-one. M.E., from O.Fr. singuler "single, separate," from L. singularis "single, solitary," from singulus "one, individual, separate," from sim- (stem of simplus) + diminutive suffix. Takin, from tak "single, alone," related to tâq "odd, single," tâ, tâh "piece, part; fold, plait, ply;" Mid.Pers. tak "single," tâg, tâk, tâi "unit, piece, after numerals" + -in adj. suffix. |
singular isothermal sphere kore-ye izodamâ-ye takin Fr.: sphère isotherme singulère In models of star formation, an isothermal sphere in which the density distribution in the static or nearly static outer envelope obeys an r^{-2} power law. In the limit of infinite central concentration, the unstable equilibrium approaches the singular isothermal sphere which has the density and mass distributions ρ(r) = (a^{2}/2πG)r^{-2} and M(r) = (2a^{2}/G)r, where a is the isothermal → sound speed inside the cloud, G is the → gravitational constant, and r the distance from the center (F. H. Shu, 1977, ApJ 214, 488). → singular; → isothermal; → sphere. |
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