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: 11 Search : periodic
aperiodic damping
  میرایی ِ نادوره‌ای   
mirâyi-ye nâdowreyi

Fr.: amortissement apériodique   

A system in which the → damping is great enough to prevent oscillation.

Aperiodic, from → a- + periodic; + → damping.

periodic
  دوره‌ای   
dowreyi (#)

Fr.: périodique   

Recurring at regular intervals of time.

Adjective of → period.

periodic comet
  دنباله‌دار ِ دوره‌ای   
dombâledâr-e dowreyi

Fr.: comète périodique   

A comet with a period of less than 200 years. Also called short-period comet.

periodic; → comet.

periodic function
  کریای ِ دوره‌ای   
karyâ-ye dowreyi

Fr.: fonction périodique   

A function f(x) if for all x, f(x + P) = f(x), where P is a positive constant. The least value of P > 0 is called the period of f(x).

periodic; → function.

periodic motion
  جنبش ِ دوره‌ای   
jonbeš-e dowreyi

Fr.: mouvement périodique   

Any motion that recurs in identical forms at equal intervals of time.

periodic; → motion.

periodic system
  راژمان ِ دوره‌ای   
râžmân-e dowreyi

Fr.: système périodique   

Arrangement of the → chemical elements in the → periodic table.

periodic; → system.

periodic table
  جدول ِ دوره‌ای   
jadval-e dowreyi (#)

Fr.: tableau périodique   

An arrangement of the → chemical elements in order of their → atomic numbers in such a way as to demonstrate periodic similarities and trends in physical and chemical properties. Elements with similar properties are arranged in the same column (called a group), and elements with the same number of → valence electrons, or number of electrons in the outer shell, are arranged in the same row (called a period). Under the latest recommendations from IUPAC (the International Union of Pure and Applied Chemistry), the groups are labelled 1 to 18 from left to right (1988, Pure and Applied Chemistry 60, 431). Also called Mendeleev's table.
The periodic table was introduced by Dmitri Ivanovich Mendeleev (1834-1907) in 1869, who originally arranged them in order of their → atomic weights. Using the table, it was possible for Mendeleev to correct some of the atomic weights (e.g. that of beryllium) and to predict the properties of a number of elements yet to be discovered (e.g. gallium, scandium, and germanium). The British physicist Frederick Soddy (1877-1956) showed that the loss of an → alpha particle reduces the nuclear charge by two and hence lowers the atomic number by two and the position of the element in the periodic table by two groups.

periodic; → table.

periodic term
  ترم ِ دوره‌ای   
tarm-e dowre-yi

Fr.: terme périodique   

In perturbation theory used in celestial mechanics, a term that indicates a bounded disturbance which recurs regularly. → secular term.

periodic; → term.

periodic wave
  موج ِ دوره‌ای   
mowj-e dowre-yi

Fr.: onde périodique   

An oscillatory motion in which each point is repeatedly displaced at equal time intervals.

periodic + → wave.

periodicity
  دوره‌ایگی   
dowreigi

Fr.: périodicité   

A state or condition characterized by regular repetition in time or space.

periodic + → -ity.

quasiperiodic motion
  جنبش ِ چونان-دوره‌ای   
jonbeš-e cunân-dowreyi

Fr.: mouvement quasipériodique   

In a dynamical system, a form of motion that is regular but never exactly repeating. Quasiperiodic motion appears when the system contains two or more incommensurate frequencies.

quasi-; → periodic; → motion.