dahbar (#), dahguš (#)
A ten-sided → polygon. A decagon that is equilateral and equiangular is called a regular decagon. Each angle of a regular decagon is 144°. The central angle subtending any side is 36°. The ratio of the radius to the side of a regular decagon forms the → golden ratio.
1) tabâhidan (#); 2) tabâhi (#), forupâši (#)
Fr.: 1) se désintegrer, se désexciter; 2) désintegration, désexcitation
1a) To become decomposed.
From O.Fr. decair, from V.L. *decadere "to fall off," from L. cadere "to fall," PIE base *kad- "to fall" (cf. Pers. Gilaki katan "to fall," ba.ka.tam "I fell," dakatan "to fall (in a marsh, in a pit)," vakatan "to fall from tiredness, be exhausted," fakatan "to fall from (lose) reputation," Pers. Laki: katen "to fall," kat "he fell," beko "fall!," Pers. Tabari: dakətə "fallen," dakətən "to crash down," dakət.gu "stray cow," Arm. chacnum "to fall").
Tabâhidan, verbal form of tabâhi, noun form of tabâh "spoiled, ruined, destroyed," Mid.Pers. tapâh "spoiled, destroyed." Maybe related to Mod.Pers. tâb "affliction, pain, torment; heat, burning," tab "fever," tâbidan, tâftan "to shine," tafsidan "to become hot," Av. tāp-, taf- "to warm up, heat," tafsat "became hot," tāpaiieiti "to create warmth," cf. Skt. tap- "to spoil, injure, damage; to suffer; to heat, be/become hot," tapati "burns," L. tepere "to be warm," tepidus "warm," PIE base *tep- "warm."
Fr.: chaîne de désintégration
A series of nuclear decays produced by successive → daughter products, when the daughters are themselves → radioactive. For example, the decay chain N1→ N2→ N3→ ... in which the parent nuclide N1 decays to the daughter N2, which in turn decays to N3. Each → radionuclide in the decay chain can → branch to more than one daughter.
Fr.: constante de désintégration
A constant of proportionality occurring in the formula expressing spontaneous → decay of → radionuclides. The number of atoms decaying is given by N = N0e-kt, where N0 is the number of nuclei in the given volume of the substance at instant t = 0, N is the number of nuclei at t, and k is decay constant. Decay constant is related to → half-life by τ = ln2/k, roughly 0.693/k.
tarz-e tabâhi, mod-e ~
Fr.: mode de désintégration
A possible type of decay of a → radionuclide or → elementary particle. In general, a given particle may decay by more than one decay mode. Usually the number of decay modes is one or two. There are, however, → nuclides which have many decay modes; for example the nuclide 11Li has seven decay modes.
Fr.: produit de désintégration
A → stable nuclide or → radioactive nuclide formed by the → disintegration of a → radioactive isotope, either directly or as a result of a → decay chain. Also called → daughter product. For example, the decay product of 238U is 206Pb, after passing through the following chain: 238U → 234Th (4.5 billion yr) → 234Pa (24 days) → 234U (1 min) → 230Th (245,000 yr) → 226Ra (76,000 yr) → 222Rn (1,600 yr) → 218Po (3.8 d) → 214Pb (3 m) → 214Bi (27 m) → 214Po (160 microseconds) → 210Pb (22 yr) → 210Bi (5 d) → 210Po (138 d) → 206Pb.
zamân-e tabâhi (#)
Fr.: temps d'amortissement
The time required for the amplitude of a vibrating system to decrease
to 1/e of its initial value.
vâšetâbidan (#); vâšetâbândan (#)
(v.intr.) To slow down. (v.tr.) To decrease the velocity of.
The act or process of moving, or of causing to move, with decreasing speed. Sometimes called negative acceleration.
Verbal noun of decelerate.
Fr.: paramètre de décéleration
A parameter designating the rate at which the expansion of the Universe would slow down owing to the braking gravitational effect of the matter content of the Universe. It is expressed by: q(t) = -R(t)R ..(t)/R .2(t), where R(t) represents the size of the Universe at time t. See also → expansion parameter; compare with → acceleration parameter.
Prefix used in the metric system to mean on-tenth.
From Fr. déci-, from L. decimus "tenth," from decem "ten," cf. Av. dasa "ten," Mod.Pers. dah "ten," Gk. deka, Skt. dasa, PIE *dekm (Dan. ti, Du. tien, Ger. zehn, E. ten, Fr. dix).
Desi-, from Fr. déci-, as above.
A dimensionless unit used to express relative difference in power or intensity, usually between two acoustic or electric signals. It is defined as n [dB] = 10 log (P1/P0), with → natural logarithm. One decibel equals one-tenth of a → bel (B).
M.E. deciden, from O.Fr. decider, from L. decidere "to decide, determine," literally "to cut off," from → de-"off" + caedere "to cut, chop, beat, hew."
Vâsunidan, from vâ- "off, away," → de-, + sun "to cut;" cf. Kurd. Soriani su, sun "to sharpen, whet;" Kurd. Kurmanji (prefixed ha-, contraction of *ham-) hasun "to sharpen, whet;" Mod.Pers. sân "whetstone," variants fasân, afsân, awsân; Av. si-, sā- "to cut;" cf. Skt. śā- "to sharpen, whet;" + -idan infinitive suffix.
Someone who decides, or something that allows to determine.
Referring to or based in the number 10; relating to tens or tenths.
M.L. decimalis "of tithes or tenths," from L. decimus "tenth," from decem, → ten.
Dahi , of or relating to dah, → ten; dahdahi literally "ten by ten."
Fr.: fraction décimale
A fraction expressed by using → decimal representation, as opposed to a vulgar fraction. For example, 2/5 is a vulgar fraction; 0.40 is a decimal fraction.
Fr.: logarithme décimal
decimal number system
râžmân-e adadhâ-ye dahdahi
Fr.: système des nombres décimaux
A system of numerals for representing real numbers that uses the → base 10. It includes the digits from 0 through 9.
raqam pas az jodâgar, ~ ~ ~ momayez
Fr.: décimale, chiffre après la virgule
The position of a digit to the right of a → decimal point written in decimal notation. In 0.032, for example, 0 is the first decimal place, 3 is the second decimal place, and 2 is the third decimal place.
jodâgar, momayez (#)
Fr.: séparateur décimal, signe décimal
A symbol (usually a point or dot) used to separate the integer part from the fractional part of a → decimal number.
Jodâgar, → separator.