An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 27 Search : dynamics
 second law of thermodynamics   قانون ِ دوم ِ گرماتوانیک   qânun-e dovom-e garmâtavânikFr.: deuxième loi de la thermodynamique   1) Heat cannot be transferred from a colder to a hotter body without some other effect, i.e. without → work being done. Expressed in terms of → entropy: the entropy of an → isolated system tends toward a maximum and its available energy tends toward a minimum. 2) In language of → statistical physics, an isolated physical system will tend toward an equilibrium → macrostate with as large a total → entropy as possible, because then the number of → microstates is the largest. See also → Kelvin's postulate, → Clausius's postulate.→ second; → law; → thermodynamics. Smoothed Particle Hydrodynamics (SPH)   هیدروتوانیک ِ ذره‌های ِ همواریده   hidrotavânik-e zarrehâ-ye hamvâridéFr.: hydrodynamique des particules lissées   A numerical method for modeling → compressible hydrodynamic flows, which uses particles to simulate a continuous fluid flow. Because the system of hydrodynamical basic equations can be analytically solved only for few exceptional cases, the SPH method provides a numerical algorithm to solve systems of coupled → partial differential equations for continuous field quantities. The main advantage of the method is that it does not require a computational grid to calculate spatial → derivatives and that it is a Lagrangian method, which automatically focuses attention on fluid elements. The equations of motion and continuity are expressed in terms of ordinary differential equations where the body forces become classical forces between particles. This method was first independently developed by Lucy (1977, AJ 82, 1013) and Gingold & Monaghan (1977, MNRAS 181, 375).Smoothed Particle Hydrodynamics, first used by Gingold & Monaghan (1977); → smooth; → particle; → hydrodynamics. statistical thermodynamics   گرماتوانیک ِ آماری   garmâtavânik-e âmâriFr.: thermodynamique statistique   Same as → statistical mechanics. stellar dynamics   توانیک ِ ستاره‌ای   tavânik-e setâre-yiFr.: dynamique stellaire   The field of astrophysics that describes systems of many → point mass particles whose mutual gravitational interactions determine their orbits. Theses systems include → star clusters, → globular clusters, and galaxies (→ galaxy) consisting of about 102-103, 104-106, and up to about 1012 members respectively. Stellar dynamics deals with systems in which each member contributes importantly to the overall gravitational field and is usually concerned with the statistical properties of many orbits. It can be compared to the → kinetic theory of gases developed in the late 19th century. In contrast, → celestial mechanics deals with systems where the gravitational force of a massive planet or star determines the orbits of its satellites.→ stellar; → dynamics. thermodynamics   گرماتوانیک   garmâtavânikFr.: thermodynamique   A branch of physics concerned with the relations between heat and other forms of energy and how these affect temperature, pressure, volume, mechanical action, and work.→ thermo-; → dynamics, coined by the Scottish physicist William Thomson (Lord Kelvin, 1824-1907), in 1849. third law of thermodynamics   قانون ِ سوم ِ گرماتوانیک   qânun-e sevom-e garmâtavânikFr.: troisième loi de la thermodynamique   The → entropy of an idealized state of maximum order is zero at the temperature of → absolute zero. Another version of this law: As a system approaches absolute zero, all processes cease and the entropy of the system approaches a minimum value.→ third; → law; → thermodynamics. zeroth law of thermodynamics   قانون ِ صفرُم ِ گرماتوانیک   qânun-e sefrom-e garmâtavânikFr.: loi zéro de la thermodynamique   Two objects that are in → thermal equilibrium with a third object will be in thermal equilibrium with each other.→ zero; → law; → thermodynamics.

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