miyângin hesâbi (#)
Fr.: moyenne arithmétique
Of n numbers a1, a2, ..., an, the quantity defined as: (a1 + a2 + ... + an)/n.
miyângin-e hendesi (#)
Fr.: moyenne géométrique
The middle term in a → geometric progression. Of two terms, the geometric mean is the square root of their product. For example, the geometric mean of 4 and 9 is ± 6. For a series of n terms, it is expressed as: (a1.a2. ... .an)1/n.
Greenwich Mean Sidereal Time (GMST)
zamân-e axtari-ye miyângin-e Greenwich
Fr.: temps sidéral moyen de Greenwich
Fr.: moyenne harmonique
A number whose reciprocal is the → arithmetic mean of the reciprocals of a set of numbers. Denoted by H, it may be written in the discrete case for n quantities x1, ..., xn, as: 1/H = (1/n) Σ(1/xi), summing from i = 1 to n. For example, the harmonic mean between 3 and 4 is 24/7 (reciprocal of 3: 1/3, reciprocal of 4: 1/4, arithmetic mean between them 7/24). The harmonic mean applies more accurately to certain situations involving rates. For example, if a car travels a certain distance at a speed speed 60 km/h and then the same distance again at a speed 40 km/h, then its average speed is the harmonic mean of 48 km/h, and its total travel time is the same as if it had traveled the whole distance at that average speed. However, if the car travels for a certain amount of time at a speed v and then the same amount of time at a speed u, then its average speed is the arithmetic mean of v and u, which in the above example is 50 km/h.
1) miyângin (#); 2) cemârdan
Fr.: 1) moyenne; 2) signifier, vouloir dire
1a) General: A quantity having a value intermediate between the values of other
quantities; an average.
Fr.: anomalie moyenne
The angle between the periapsis of an orbit and the position of a hypothetical body that orbits in the same period as the real one but at a constant mean angular velocity.
mean catalog place
jâ-ye miyângin-e kâtâlogi
Fr.: position catalogue moyenne
mean daily motion
jenbeš-e ruzâne-ye miyângin (#)
Fr.: mouvement diurne moyen
The average movement of a body along its orbit in one day, usually expressed in degrees.
Fr.: élément moyen
An element of an adopted reference orbit that approximates the actual, perturbed orbit. Mean elements may serve as the basis for calculating perturbations.
Fr.: équateur moyen
The orientation the Earth's equator would have if the nutation was subtracted.
Fr.: équinoxe moyen
A fictitious equinox whose position is that of the vernal equinox at a particular epoch with the effect of nutation removed.
mean free path
puyeš-e âzâd-e miyângin (#)
Fr.: libre parcours moyen
The mean distance which a particle moves between two successive collisions with other particles of the medium. Mean free path is inversely proportional to the number of particles per cm3 (n), and the collision → cross section (σ). In the case of a gas with molecules having a diameter of d, the cross section is equal to the area of a circle of radius d, i.e. σ = πd2, and the mean free path is given by: l = 1/(nσ). Taking into account the relative velocity distribution of the colliding molecules, l = 1/(√2 . nσ). For a gas at one atmosphere pressure and room temperature, the average distance between molecules is roughly 3.5 × 10-7 cm, that is some 35 times the diameter of a molecule. Taking the gas density n = 2.4 × 1014 molecules cm-3, and a typical diameter d = 2 × 10-8 cm for a molecule, the mean free path is 3.3 × 10-5 cm. This means that the average distance between collisions is about 95 times the average distance between molecules.
Fr.: vie moyenne
The average amount of time an unstable radioisotope exists before it decays, It is equal to 1.44 times the half-life.
mean molecular weight
vazn-e molekuli-ye miyângin (#)
Fr.: poids moléculaire moyen
The total atomic or molecular weight divided by the total number of particles. For instance, the mean molecular weight of a plasma of pure ionized 4He would be 4 (the atomic mass number) divided by 3, the total number of particles (1 nucleus plus 2 electrons), i.e. 4/3.
mâh-e miyângin (#)
Fr.: lune moyenne
A fictitious Moon that has the same average motion as the true Moon but that is not subject to any gravitational perturbations by other bodies.
jonbeš-e miyângin (#)
Fr.: mouvement moyen
The average angular velocity of a satellite in an elliptical orbit.
Fr.: parallaxe moyenne
The parallax, derived by means of statistical studies of brightness and motions, for a large group of stars whose individual parallaxes cannot be measured.
Fr.: position moyenne
An object's celestial position as determined for a given mean equator and equinox. → mean position.
Fr.: pôle moyen
The direction of the Earth's axis at a particular epoch if the nutation is ignored.
Fr.: position moyenne
Same as → mean place.