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

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Number of Results: 9 Search : section
collisional cross section
  سکنج ِ اسکرمند ِ همکوبشی   
sekanj-e oskarmand-e hamkubeši

Fr.: section efficace de collision   

Same as → cross section.

collisional; → cross; → section.

conic section
  سکنج ِ مخروطی   
sekanj-e maxruti

Fr.: section conique   

A curve which may be represented as the intersection of a plane with a cone; hence a → parabola, → hyperbola, or → ellipse.

cone; → section.

cross section
  سکنج‌گاه   
sekanjgâh

Fr.: 1) section plane; 2) section efficace   

1) Math: The intersection of a plane with a geometric figure, usually at right angles to an axis of symmetry.
2) Physics: A quantity that expresses the effective area that a given particle presents as a target to another incident particle, giving a measure of the probability that the incident particle will induce a particular atomic or nuclear reaction. Also called collision cross section. The cross section has the dimensions of a surface. In nuclear and particle physics, the commonly used units for the cross section are the barn and cm2.

In classical mechanics, the cross section for the collision of a point particle with a hard sphere is just be the surface of a section through the middle of the sphere. This explains the name "cross section." → cross; → section.

dissection
  واسکنجش   
vâsekanješ

Fr.: dissection   

The act of dissecting.

dissect; → -tion.

intersection
  اندربرش، اندرسکنج   
andarboreš, andarsekanj

Fr.: intersection   

The act, process, or result of intersecting.
Math.: A set of elements common to sets A and B, denoted by A ∩ B. → section.

Verbal noun of → intersect.

minimum orbit intersection distance (MOID)
  دورای کمینه‌ی ِ اندرسکنج ِ مدار   
durâ-ye kamine-ye andarsekanj-e madâr

Fr.: distance minimale d'intersection d'une orbite   

The minimum distance between the paths of two orbiting objects around a → primary. Such distance between an object and Earth is called Earth MOID.

minimum; → orbit; → intersection; → distance.

nuclear cross-section
  سکنج‌گاه ِ هسته‌ای   
sekanjgâh-e hasteyi

Fr.: section efficace nucléaire   

Apparent cross-section possessed by an atomic nucleus when it undergoes a particular type of collision process.

nuclear; → cross section.

section
  سکنج   
sekanj (#)

Fr.: section   

A part that is cut off or separated.
A distinct part or subdivision of anything. → cross section; → intersection

From M.Fr. section, from L. sectionem "a cutting, division," from secare "to cut;" PIE base *sek- "cut" (cf. O.C.S. seko, sesti "to cut," Lith. isekti "to engrave, carve;" O.S. segasna, O.E. sigðe "scythe;" O.E. secg "sword," seax "knife, short sword").

Sekanj "a scraping, shaving, cutting," cognate with Pers. šekast-, šekastan "to break;" Av. skand- "to break," Skt. khand- "to break," khanda- "piece;" Pers. dialect Tabari šag "a special razor used to make incisions in the walls of unripe opium poppies in order to extract the milky sap," may be related to PIE *sek- "cut," as above.

Thomson cross section
  سکنج‌گاه ِ تامسون   
sekanjgâh-e Thomson

Fr.: section efficace de Thomson   

The → cross section involved the → Thomson scattering of electromagnetic waves by a free electron. It is defined by: σT = 8πre2/3, where re is the classical → electron radius. Its value is 0.665 245 x 10-28 m2.

Thomson; → cross; → section.