An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 473
linear equation
  هموگش ِ خطی   
hamugeš-e xatti

Fr.: équation linéaire   

An equation composed of first degree variables and representing a straight line.

linear; → equation.

linear function
  کریای ِ خطی   
karyâ-ye xatti

Fr.: fonction linéaire   

A function expressed by a → first degree equation that can be graphically represented in the → Cartesian coordinate plane by a → straight line.

linear; → function.

linear instability
  ناپایداری ِ خطی   
nâpâydâri-ye xatti (#)

Fr.: instabilité linéaire   

An instability that can be described (to first-order accuracy) by linear (or tangent linear) equations.

linear; → instability.

linear momentum
  جنباک ِ خطی   
jonbâak-e xatti

Fr.: quantité de mouvement linéaire   

The product of an object's → mass and → velocity. It is a → vector and points in the same direction as the velocity vector. Linear momentum is distinguished from → angular momentum. When there is no opportunity for confusion, usually the term momentum is used instead of linear momentum.

linear; → momentum.

linear perturbation theory
  نگره‌ی ِ پرتورش ِ خطی   
negare-ye partureš-e xatti

Fr.: théorie de perturbation linéaire   

Assumption that the variations in the plasma parameters, due to the presence of waves, are small (to the first order) as compared to the undisturbed parameters. This makes it possible to linearize equations by dropping out second order (and higher) nonlinear terms.

linear; → perturbation; → theory.

linear polarization
  قطبش ِ خطی   
qotbeš-e xatti (#)

Fr.: polarisation linéaire   

Of an electromagnetic radiation, a → polarization in which the electric vibrations are confined to one plane along the direction of propagation. Also called → plane polarization. See also → circular polarization.

linear; → polarization.

linear programming
  برنامه‌سازی ِ خطی   
barnâme-sâzi-ye xatti (#)

Fr.: programmation linéaire   

A procedure for finding the maximum or minimum of a → linear function where the → arguments are subject to linear → constraints. For problems involving more than two variables or problems involving a large number of constraints, solution methods used are those that are adaptable to computers. A well-known such → algorithm is the → simplex method.

linear; → programmings.

linear regression
  وایازی ِ خطی   
vâyâzi-ye xatti

Fr.: regression linéaire   

In statistics, a regression method that establishes a linear relationship between two random variables.

linear; → regression.

linear size
  اندازه‌ی ِ خطی   
andâze-ye xatti

Fr.: taille linéaire   

The real, physical size, as opposed to angular size.

linear; → size.

linear system
  راژمان ِ خطی   
râžmân-e xatti

Fr.: système linéaire   

Physics: A → dynamical system whose evolution is a linear process. If a change in any variable at some initial time produces a change in the same or some other variable at some later time, twice as large a change at the same initial time will produce twice as large a change at the same later time.

linear; → system.

linear velocity
  تندای ِ خطی   
tondâ-ye xatti

Fr.: vitesse linéaire   

The rate of change of the position of an object that is traveling along a straight path. In other words, the velocity of an object when its moving direction is not changing. For a given → angular velocity (ω), the linear velocity v of the particle is directly proportional to the distance of the particle from the center of the circular path: v = ω ×r.

linear; → velocity.

linearity
  خطیگی   
xattigi

Fr.: linéarité   

The property, condition, or state of being linear.
Math.: A relationship between two variables so that when plotted on a graph they yield a straight line.

linear; → -ity.

linearization
  خطش، خطانش   
xatteš, xattâneš

Fr.: linéarisation   

A process of reduction to linear form by appropriate change of variables or by approximation.

Verbal noun of → linearize.

linearize
  خطیدن، خطانیدن   
xattidan, xattânidan

Fr.: linéariser   

To make linear; give linear form to.

linear + → -ize.

linearized differential equation
  هموگش ِ دگرسانه‌ای ِ خطی   
hamugeš-e degarsâneyi-ye xatti

Fr.: équation différentielle linéarisée   

A differential equation that has been derived from an original nonlinear equation.

Linearized, p.p. of → linearize; → differential; → equation.

linearly
  خطانه   
xattâné

Fr.: linéairement   

In a manner characterized by first-degree algebraic terms.

Adverb of → linear.

linearly dependent
  خطانه وابسته   
xattâné vâbasté

Fr.: linéairement dépendant   

A set of objects x1, x2, ..., xn (→ vectors, → matrices, → polynomials, etc.) on a given set if there is a linear combination of them: a1x1 + a2x2 + ... + anxn, which is zero, but at least one of the coefficients is non-zero. For example the binomials (2x + y) and (6x + 3y) are linearly dependent, since 3(2x + y) - (6x + 3y) = 0.

linearly; → dependent.

linearly independent
  خطانه ناوابسته   
xattâné nâvâbasté

Fr.: linéairement indépendant   

1) A set of objects x1, x2, ..., xn (→ vectors, → matrices, → polynomials, etc.) if it si not → linearly dependent.
2) Of two particular solutions (y1, y2) of a → homogeneous linear differential equation of the second order (y'' + a1 y' + a2y = 0) on an interval [a, b], if their ratio in this interval is not a constant: y1/y2≠ constant.

linearly; → independent.

linearly polarized light
  نور ِ قطبیده‌ی ِ خطی   
nur-e qotbide-ye xatti

Fr.: lumière polarisée linéairement   

Light exhibiting → linear polarization.

linearly; → polarized; → light.

LINER
  لاینر   
lâyner (#)

Fr.: LINER   

A type of galactic nucleus that is defined by its spectral line emission. The lines are very weak, the most prominent ones being from low ionization states (such as [O II], [N II], [S II] and [OI]). There is so far no generally accepted interpretation of the spectra of liners. It is likely that galaxies of different histories may have their nuclei with liner-type spectra. → retired galaxy.

Short for → Low-Ionization Nuclear Emission-line Region. The term liner was first introduced by T. M. Heckman (1980, A&A 87, 152).

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