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  2. R-factor (crystallography) - Wikipedia

    en.wikipedia.org/wiki/R-factor_(crystallography)

    In the Cambridge Structural Database of small-molecule structures, more than 95% of the 500,000+ crystals have an R-factor lower than 0.15, and 9.5% have an R-factor lower than 0.03. Crystallographers also use the Free R-Factor ( R F r e e {\displaystyle R_{Free}} ) [ 3 ] to assess possible overmodeling of the data.

  3. Robinson–Foulds metric - Wikipedia

    en.wikipedia.org/wiki/Robinson–Foulds_metric

    The Robinson–Foulds or symmetric difference metric, often abbreviated as the RF distance, is a simple way to calculate the distance between phylogenetic trees. [1]It is defined as (A + B) where A is the number of partitions of data implied by the first tree but not the second tree and B is the number of partitions of data implied by the second tree but not the first tree (although some ...

  4. Reflectance - Wikipedia

    en.wikipedia.org/wiki/Reflectance

    The directional reflectance of a surface, denoted R Ω, is defined as [1] =,,, where . L e,Ω r is the radiance reflected by that surface;; L e,Ω i is the radiance received by that surface.

  5. CIE 1931 color space - Wikipedia

    en.wikipedia.org/wiki/CIE_1931_color_space

    When two or more colors are additively mixed, the x and y chromaticity coordinates of the resulting color (x mix,y mix) may be calculated from the chromaticities of the mixture components (x 1,y 1; x 2,y 2; …; x n,y n) and their corresponding luminances (L 1, L 2, …, L n) with the following formulas: [16]

  6. Permeability (electromagnetism) - Wikipedia

    en.wikipedia.org/wiki/Permeability...

    For example, 4% electrical steel has an initial relative permeability (at or near 0 T) of 2,000 and a maximum of 38,000 at T = 1 [5] [6] and different range of values at different percent of Si and manufacturing process, and, indeed, the relative permeability of any material at a sufficiently high field strength trends toward 1 (at magnetic ...

  7. X-ray fluorescence - Wikipedia

    en.wikipedia.org/wiki/X-ray_fluorescence

    In scientific methods that use X-ray/neutron or electron diffraction the before mentioned planes of a diffraction can be doubled to display higher order reflections. The given planes, resulting from Miller indices, can be calculated for a single crystal. The resulting values for h, k and l are then called Laue indices. So a single crystal can ...

  8. Extremely low frequency - Wikipedia

    en.wikipedia.org/wiki/Extremely_low_frequency

    For example, a 3 Hz signal has a wavelength equal to the distance electromagnetic waves travel through a given medium in one third of a second. When the refractive index of the medium is greater than one, ELF waves propagate slower than the speed of light in vacuum. As used in military applications, the wavelength is 299,792 km (186,282 mi) per ...

  9. Chromaticity - Wikipedia

    en.wikipedia.org/wiki/Chromaticity

    For example, the white point of an sRGB display is an x, y chromaticity of (0.3127, 0.3290), where x and y coordinates are used in the xyY space. ( u′ , v′ ) , the chromaticity in CIELUV , is a fairly perceptually uniform presentation of the chromaticity as (another than in CIE 1931) planar Euclidean shape.