bottom-up structure formation
diseš-e sâxtâr az pâyin bé bâlâ
Fr.: formation des structures du bas vers le haut
1) bandidé; 2) karân
Fr.: lié; lien
Fr.: charge liée
Any electric charge which is bound to an atom or molecule, in contrast to free charge, such as metallic conduction electrons, which is not. Also known as → polarization charge.
Fr.: amas lié
A cluster of astronomical objects, such as stars or galaxies, held together by their mutual gravitational attraction. → bound system.
Fr.: occurrence liée
Fr.: orbite liée
The orbit described by an object around a central gravitational force in a system whose total energy is negative. An elliptical orbit.
Fr.: système lié
A system composed of several material bodies the total energy of which (the sum of kinetic and potential energies) is negative, e.g. a → bound cluster.
Fr.: transition liée-liée
Fr.: transition liée-libre
Fr.: limite, bord
Something that indicates a border or limit; the border or limit so indicated.
From Fr., from O.Fr. bodne, from M.L. bodina, butina "boundary, boundary marker."
Karân, karâné, kenâr from Mid.Pers. karânag, Av. karana- "boundary."
butârhâ-ye karân, ~ karâni
Fr.: conditions à la limite
1) Math: Restriction on the limits of applicability of an equation.
In a differential equation, conditions that allow to fix the constant
of integration and reach a unique solution. The number of boundary conditions
necessary to determine a solution matches the order of the equation.
Fr.: effet de bords
An effect that forbids or invalidate locally the use of an idealized model of a system in which one or several of its dimensions are supposed to be infinite.
Fr.: couche limite
A layer of fluid that is formed wherever a fluid flows past a solid surface and the effects of → viscosity are important. The boundary level forms because as the fluid moves past the object, the molecules which are in direct contact with the surface stick to the surface. The molecules just above the surface are slowed down in their collisions with the molecules sticking to the surface. These molecules in turn slow down the flow just above them, but less effectively. This creates a thin layer of fluid near the surface in which the velocity changes from zero at the surface to the free stream value away from the surface. The boundary layer may be either → laminar or → turbulent in character, depending on the value of the → Reynolds number. The concept of boundary level was first put forward by Ludwig Prandlt (1875-1953) in 1904.
karânmand (#), karândâr (#)
General: Having bounds or limits.
Adj. from → bound.
karyâ-ye karânmand, ~ karândâr
Fr.: fonction bornée
The function y = f(x) in a given range of the argument x if there exists a positive number M such that for all values of x in the range under consideration the inequality | f(x) | ≤ M will be fulfilled. → unbounded function.
Fr.: approximation de Boussinesq
A simplification in the equations of → hydrodynamics that treats the density as constant except in the → buoyancy term. This approximation is motivated by the fact that when pressure and temperature differences in a flow are small, then it follows from the thermodynamic → equation of state that a change in the density is also small.
Named after Joseph Valentin Boussinesq (1842-1929), a French physicist who made significant contributions to the theory of hydrodynamics, vibration, light, and heat; → approximation.
1) kamân; 2) farâl
1a) A bent, curved, or arched object.
1) M.E., from O.E. boga "archery bow, arch, rainbow" (cf.
O.Norse bogi, Du. boog, Ger. Bogen "bow");
PIE root *bheug- "to bend;" cf. Skt. bhujati "bends;"
O.H.G. boug, O.E. beag "a ring").
1) Kamân "bow, arc," from Mid.Pers. kamân, related to xam "curve," cf. Breton kamm "curved, bent," Gk. kampe "a corner, a joint," L. campus "a field," Lith. kampus "corner," PIE *kamb- "to bend, crook." Farâl, from farâ "forward" (farâ raftan "to go forward, proceed," farâ rândan "to drive forward"), equivalent to → pro-, + relation suffix -âl, → -al. Compare farâl with prow "bow," Fr. la proue "prow, bow," from dialectal It. proa, prua, from L. prora "bow," from Gk. proira, related to pro "before, forward."
Fr.: choc de proue
farâl-mowj, mowj-e farâl
Fr.: onde de proue
The wave which appears in front of a speeding boat and goes out behind it in a distinctive "V". It is due to the fact that waves pile up on each other before they can move away.
Bowen fluorescence mechanism
sâzokâr-e fluoresti-ye Bowen
Fr.: mécanisme de fluorescence de Bowen
A mechanism, made possible by certain chance coincidences between → spectral lines of He II, O III and N III in some → planetary nebulae , that explains the presence with a high intensity of a selected group of O III and N III lines while all other lines of these elements are missing.