Fr.: mécanisme de Eley-Rideal
A → chemical reaction on solid surfaces in which one atom or molecule is → adsorbed on the catalyst surface, and another reacts directly from the gas phase. This type of mechanism may occur preferentially on very small → dust grains, where transient heating events prevent weakly bound species from remaining and in larger grains at high temperatures. Compare with the → Langmuir-Hinshelwood mechanism.
Proposed in 1938 by D. D. Eley (1914-2015), a British chemist and Professor of Physical Chemistry and E. K. Rideal (1890-1974), an English physical chemist.
1) (n.) ârmân (#), minevâr; 2) (adj.) ârmâni (#), mineyi, minevâr
1) (n.) A standard of perfection, beauty, or excellence.
M.E. ydeall, from L.L. idealis "existing in idea," from L. → idea.
Ârmân "ideal" in Mod.Pers., traditionally "desire; hope; grief," variants
armân, urmân, prefixed from mân, "thought, mind," → idea.
The first element may be related to Av. armaē- "in peace, still; quietly;"
PIE base *er[ə]- "to be still" (cf. Skt. īrmā (adv.) "quiet,
still, being in the same place;" Gk. erôé "calm, peace;" O.H.G. rouwa
"rest"), as in Av. armaē.šad- "sitting quietly,"
armaē.štā- "standing still, stagnant." Therefore, Pers. ârmân
may be related to Av. *armaē.manah- (PIE *ermen-)
"thought in peace, quiet mind."
šâre-ye ârmâni, ~ minevâr
Fr.: fluide idéal
gâz-e ârmâni, ~-e minevâr
Fr.: gaz idéal
Theoretical gas assumed to consist of perfectly elastic molecules of negligible volume and mutual attraction force. Also called → perfect gas.
ideal gas law
qânun-e gâz-e ârmâni, ~ ~ minevâr
Fr.: loi des gaz parfaits
An → equation of state that relates pressure (P), temperature (T), and volume (V) of an ideal or → perfect gas: PV = nRT, where n is the number of → moles of gas present and R is the → universal gas constant. Equivalently: PV = NkT, where N is the number of atoms of gas present and k is → Boltzmann's constant.
ideal magnetohydrodynamics (MHD)
meqnâtohidrotavânik-e ârmâni, ~ minevâr
Fr.: magnétohydrodynamique idéale
Magnetohydrodynamics of a → plasma with very large (infinite) → conductivity. In this condition, → Ohm's law reduces to E = -v × B, where E represents → electric field, B → magnetic field, and v the → fluid velocity. Ideal MHD is the simplest model to describe the dynamics of plasmas immersed in a magnetic field. It is concerned with → one-fluid magnetohydrodynamics and neglects → resistivity. This theory treats the plasma composed of many charged particles with locally neutral charge as a continuous single → fluid. Ideal MHD does not provide information on the velocity distribution and neglects the physics relating to wave-particle interactions, as does the two-fluid theory as well. It does have the advantage that the macroscopic dynamics of the → magnetized plasma can be analyzed in realistic three-dimensional geometries (K. Nishikawa & M. Wakatani, 2000, Plasma Physics, Springer). See also → non-ideal magnetohydrodynamics.
Any one of a variety of systems of philosophical thought, which would make the ultimate reality of the Universe expressible or intangible only in terms of idea in mind, rather than in terms of matter in space.
non-ideal magnetohydrodynamics (MHD)
meqnâtohidrotavânik-e nâ-ârmâni, ~ nâ-minevâr
Fr.: magnétohydrodynamique non idéale
A → magnetohydrodynamics approach dealing with → plasmas which is an improvement with respect to → ideal magnetohydrodynamics. Non-ideal magnetohydrodynamics allows for a drift between particles, redistributing the → magnetic flux and acting on both the → angular momentum and magnetic flux conservation issues.