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

1) Of a curve, free from bumps or abrupt irregularities.
2) To modify a sequential set of numerical data by reducing the differences in magnitude between adjacent values.

O.E. smoð "free from roughness, not harsh," of unknown origin.

Hamvâr "level, equal, an even place or thing," from ham- "same, equally, even; together, with" (Mid.Pers. ham-, like L. com- and Gk. syn- with neither of which it is cognate. O.Pers./Av. ham-, Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-, Gk. homos-; originally identical with PIE numeral *sam- "one," from *som-. The Av. ham- appears in various forms: han- (before gutturals, palatals, dentals) and also hem-, hen-) + -vâr similarity suffix.

1) A curve which is free from abrupt fluctuations.
2) A curve if it has tangents at all points and the angle of inclination of the tangent is a continuous function of the arc length.

→ smooth; → curve.

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.

An average of 13 monthly → sunspot numbers, centered on the month of concern. The 1st and 13th months are given a weight of 0.5.

→ smooth; → sunspot; → number.

The mathematical process that makes a curve smooth.

Verbal noun of → smooth.

A low-pass filter designed to reduce the amplitude of a ripple while freely passing the direct current obtained from a rectifier or direct-current generator. Also known as smoothing filter.

→ smoothing; → circuit.