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Per-unit system. In the power systems analysis field of electrical engineering, a per-unit system is the expression of system quantities as fractions of a defined base unit quantity. Calculations are simplified because quantities expressed as per-unit do not change when they are referred from one side of a transformer to the other.
In the study of heat transfer, Schwarzschild's equation[ 1][ 2][ 3] is used to calculate radiative transfer ( energy transfer via electromagnetic radiation) through a medium in local thermodynamic equilibrium that both absorbs and emits radiation. The incremental change in spectral intensity, [ 4] ( dIλ, [W/sr/m 2 /μm]) at a given wavelength ...
The simplest case refers to the formation of a strictly linear polymer by the reaction (usually by condensation) of two monomers in equimolar quantities. An example is the synthesis of nylon-6,6 whose formula is [−NH−(CH 2) 6 −NH−CO−(CH 2) 4 −CO−] n from one mole of hexamethylenediamine, H 2 N(CH 2) 6 NH 2, and one mole of adipic acid, HOOC−(CH 2) 4 −COOH.
The Mach number is named after the physicist and philosopher Ernst Mach [3] according to a proposal by the aeronautical engineer Jakob Ackeret in 1929. [4] The word Mach is always capitalized since it derives from a proper name, and since the Mach number is a dimensionless quantity rather than a unit of measure, the number comes after the word Mach; the second Mach number is Mach 2 instead of ...
The equation is named after Henry Darcy and Julius Weisbach. Currently, there is no formula more accurate or universally applicable than the Darcy-Weisbach supplemented by the Moody diagram or Colebrook equation. [1] The Darcy–Weisbach equation contains a dimensionless friction factor, known as the Darcy friction factor. This is also ...
Churchill equation [24] (1977) is the only equation that can be evaluated for very slow flow (Reynolds number < 1), but the Cheng (2008), [25] and Bellos et al. (2018) [8] equations also return an approximately correct value for friction factor in the laminar flow region (Reynolds number < 2300). All of the others are for transitional and ...
In scientific notation, nonzero numbers are written in the form. m × 10 n. or m times ten raised to the power of n, where n is an integer, and the coefficient m is a nonzero real number (usually between 1 and 10 in absolute value, and nearly always written as a terminating decimal ). The integer n is called the exponent and the real number m ...
[19] [6] [16] [27] Texts and programs "simplifying" model specification via diagrams or by using equations permitting user-selected variable names, re-convert the user's model into some standard matrix-algebra form in the background. The "simplifications" are achieved by implicitly introducing default program "assumptions" about model features ...