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  2. Near-infrared spectroscopy - Wikipedia

    en.wikipedia.org/wiki/Near-infrared_spectroscopy

    NIR absorption bands are typically 10–100 times weaker than the corresponding fundamental mid-IR absorption band.) [4] The lower absorption allows NIR radiation to penetrate much further into a sample than mid infrared radiation. Near-infrared spectroscopy is, therefore, not a particularly sensitive technique, but it can be very useful in ...

  3. Atwater system - Wikipedia

    en.wikipedia.org/wiki/Atwater_system

    The Atwater system, [1] named after Wilbur Olin Atwater, or derivatives of this system are used for the calculation of the available energy of foods.The system was developed largely from the experimental studies of Atwater and his colleagues in the later part of the 19th century and the early years of the 20th at Wesleyan University in Middletown, Connecticut.

  4. Near-infrared window in biological tissue - Wikipedia

    en.wikipedia.org/wiki/Near-infrared_window_in...

    The near-infrared (NIR) window (also known as optical window or therapeutic window) defines the range of wavelengths from 650 to 1350 nanometre (nm) where light has its maximum depth of penetration in tissue. [1] Within the NIR window, scattering is the most dominant light-tissue interaction, and therefore the propagating light becomes diffused ...

  5. Normalized difference water index - Wikipedia

    en.wikipedia.org/wiki/Normalized_Difference...

    McFeeters index: If looking for water bodies or change in water level (e.g. flooding), then it is advisable to use the green and NIR spectral bands [18] or green and SWIR spectral bands. Modification of normalised difference water index (MNDWI) has been suggested for improved detection of open water by replacing NIR spectral band with SWIR. [19]

  6. Water activity - Wikipedia

    en.wikipedia.org/wiki/Water_activity

    The definition of a w is where p is the partial water vapor pressure in equilibrium with the solution, and p* is the (partial) vapor pressure of pure water at the same temperature. An alternate definition can be a w ≡ l w x w {\displaystyle a_{w}\equiv l_{w}x_{w}} where l w is the activity coefficient of water and x w is the mole fraction of ...

  7. Reduced properties - Wikipedia

    en.wikipedia.org/wiki/Reduced_properties

    The reduced temperature of a fluid is its actual temperature, divided by its critical temperature: [1] = where the actual temperature and critical temperature are expressed in absolute temperature scales (either Kelvin or Rankine). Both the reduced temperature and the reduced pressure are often used in thermodynamical formulas like the Peng ...

  8. Phase rule - Wikipedia

    en.wikipedia.org/wiki/Phase_rule

    In thermodynamics, the phase rule is a general principle governing multi-component, multi-phase systems in thermodynamic equilibrium.For a system without chemical reactions, it relates the number of freely varying intensive properties (F) to the number of components (C), the number of phases (P), and number of ways of performing work on the system (N): [1] [2] [3]: 123–125

  9. Antoine equation - Wikipedia

    en.wikipedia.org/wiki/Antoine_equation

    The Antoine equation is a class of semi-empirical correlations describing the relation between vapor pressure and temperature for pure ... Water 8.07131: 1730.63: 233 ...