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  2. Color difference - Wikipedia

    en.wikipedia.org/wiki/Color_difference

    The International Commission on Illumination (CIE) calls their distance metric ΔE* (also inaccurately called dE*, dE, or "Delta E") where delta is a Greek letter often used to denote difference, and E stands for Empfindung; German for "sensation". Use of this term can be traced back to Hermann von Helmholtz and Ewald Hering.

  3. Dirac delta function - Wikipedia

    en.wikipedia.org/wiki/Dirac_delta_function

    In mathematical analysis, the Dirac delta function (or δ distribution), also known as the unit impulse, [1] is a generalized function on the real numbers, whose value is zero everywhere except at zero, and whose integral over the entire real line is equal to one.

  4. Taft equation - Wikipedia

    en.wikipedia.org/wiki/Taft_equation

    For the definition reaction series δ was set to 1 and E s for the reference reaction was set to zero. This equation is combined with the equation for σ* to give the full Taft equation. From comparing the E s values for methyl, ethyl, isopropyl, and tert-butyl, it is seen that the value

  5. Levi-Civita symbol - Wikipedia

    en.wikipedia.org/wiki/Levi-Civita_symbol

    In two dimensions, the Levi-Civita symbol is defined by: = {+ (,) = (,) (,) = (,) = The values can be arranged into a 2 × 2 antisymmetric matrix: = (). Use of the two-dimensional symbol is common in condensed matter, and in certain specialized high-energy topics like supersymmetry [1] and twistor theory, [2] where it appears in the context of 2-spinors.

  6. Partition function (statistical mechanics) - Wikipedia

    en.wikipedia.org/wiki/Partition_function...

    It may not be obvious why the partition function, as we have defined it above, is an important quantity. First, consider what goes into it. The partition function is a function of the temperature T and the microstate energies E 1, E 2, E 3, etc. The microstate energies are determined by other thermodynamic variables, such as the number of ...

  7. Delta SkyMiles Value: How Much Are Your Miles Worth? - AOL

    www.aol.com/finance/delta-skymiles-value-much...

    As one of the leading global airlines, Delta has always provided a plethora of affordable flights and a generous frequent flyer program, too. However, significant changes to the program, set to be...

  8. Van 't Hoff equation - Wikipedia

    en.wikipedia.org/wiki/Van_'t_Hoff_equation

    where ln denotes the natural logarithm, is the thermodynamic equilibrium constant, and R is the ideal gas constant.This equation is exact at any one temperature and all pressures, derived from the requirement that the Gibbs free energy of reaction be stationary in a state of chemical equilibrium.

  9. Penetration depth - Wikipedia

    en.wikipedia.org/wiki/Penetration_depth

    Penetration depth is one term that describes the decay of electromagnetic waves inside of a material. The above definition refers to the depth at which the intensity or power of the field decays to 1/e of its surface value. In many contexts one is concentrating on the field quantities themselves: the electric and magnetic fields in the case of ...