Of or pertaining to → aberration.
→ aberration; → -al.
aberrational day number
šomâre-ye ruz-e birâheši
Fr.: nombre de jours d'aberration
A → Besselian day number denoted by C or D.
→ aberration; → -al; → day; → number.
Fr.: ellipse d'aberration
The → locus of points on the → celestial sphere occupied by a star during the annual → revolution of the → Earth about the → Sun due to → annual aberration. annual aberration.
→ aberrational; → ellipse.
Fr.: nombre irrationnel
A → real number which cannot be exactly expressed as a ratio a/b of two integers. Irrational numbers have decimal expansions that neither terminate nor become periodic. Every → transcendental number is irrational. The most famous irrational number is √ 2.
From ir- a prefix meaning "not," a variant of → in-, + → rational; → number.
Pertaining to a process or series of actions for achieving a result.
Adj. of → operation.
Fr.: calcul opérationnel
A method of mathematical analysis which in many cases makes it possible to reduce the study of differential operators, pseudo-differential operators and certain types of integral operators, and the solution of equations containing them, to an examination of simpler algebraic problems. It is also known as operational analysis.
→ operational; → calculus.
In the philosophy of science, the view that → concepts are defined in terms of measuring operations which determine their applicability. Same as operationism.
1) râyani, râyanvâr; 2) xeradâné, xeradmandâné; 3) vâbari
1) Having or exercising the ability to → reason.
M.E. racional, from O.Fr. racionel, from L. rationalis "of or belonging to reason, reasonable," from ratio (genitive rationis) "reckoning, calculation, reason," from rat-, pp. stem of reri "to reckon, calculate; consider, think."
1) Râyani, of or pertaining to râyan, → reason.
Fr.: nombre rationnel
Any number that can be expressed as a ratio of two integers, providing the second number is not zero.
Fr.: raisonnement, exposé raisonné
1) The fundamental reason or reasons serving to account for something.
L. neuter of rationalis.
A philosophical doctrine that holds that → reason alone, unaided by experience, can arrive at basic truth regarding the world.
From → rational + -ism a Gk. suffix used in the formation of nouns denoting action or practice, state or condition, principles, doctrines, and so forth.
Râyan, → reason; xerad, → rational; bâvari, from bâvar "belief" (Mid.Pers. wâbar "beleif;" Proto-Iranian *uar- "to choose; to convince; to believe;" cf. Av. var- "to choose; to convince" varəna-, varana- "conviction, faith;" O.Pers. v(a)r- "to choose; to convince;" Skt. vr- "to choose," vara- "choosing").
Of or pertaining to → vibration. → vibrational mode.
Fr.: énergie de vibration, ~ vibratoire
The energy due to the vibration of the molecules making up atoms (→ molecular vibration). A molecule in space can have energies in various forms: → rotational energy, vibrational energy, or electronic energy. These energies of molecules are → quantized and a particular molecule can exist in different rotational and vibrational → energy levels. The molecules can move from one level to another level only by a jump involving a finite amount of energy. → Quantum mechanics predicts that any molecule can never have zero vibrational energy, that is atoms can never be completely at rest relative to each other. The harmonically oscillating molecules can undergo vibrational changes determined by simple selection rules obtained from → Schrödinger equation.
→ vibrational; → energy.
basâmad-e šiveši (#)
Fr.: fréquence de vibration, ~ vibrationnelle
The frequency at which the atoms in a molecule vibrate. The frequencies of → molecular vibrations in diatomic molecules are in the order of 10-12 to 10-14 Hz. In such molecules, the only → vibrational mode available is along the bond. More complicated molecules have many types of vibration and stretching modes.
→ vibrational; → frequency.
Fr.: mode de vibration, ~ vibratoire
Any of the ways in which a → molecule vibrates. Each vibrational mode has a different → frequency frequency. The number of vibrational modes of a molecule is determined by the number of atoms in it. The number of vibrational modes for a non-linear molecule is 3N - 6, where N is the number of atoms making up the molecule. For a linear molecule it is 3N - 5.
→ vibrational; → mode.
Fr.: transition vibrationnelle
A transition between two → quantized → levels of a → molecule that have different vibrational energies.
→ vibrational; → transition.
Fr.: transition vibrationnelle-rotationnelle
A slight change in the → energy level of a → molecule due to → vibrational transition and/or → rotational transition.
→ vibrational; → rotational; → transition.