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  2. Grating - Wikipedia

    en.wikipedia.org/wiki/Grating

    The grating profile is the function of the reflectance or transmittance perpendicular to the lines. This function is generally a square wave, in that every transition between lines is abrupt. A grating can be defined by six parameters: Spatial frequency is the number of cycles occupying a particular distance (e.g. 10 line pairs per millimeter ...

  3. Echelle grating - Wikipedia

    en.wikipedia.org/wiki/Echelle_grating

    An echelle grating (from French échelle, meaning "ladder") is a type of diffraction grating characterised by a relatively low groove density, but a groove shape which is optimized for use at high incidence angles and therefore in high diffraction orders. Higher diffraction orders allow for increased dispersion (spacing) of spectral features at ...

  4. Heating system - Wikipedia

    en.wikipedia.org/wiki/Heating_system

    Distributed heating systems: These systems generate heat in the space they are to heat, without extensive duct systems. Examples include electric space heaters, fireplaces, and solar heating. [3] Heat pumps: They can be used for heating and cooling, transferring heat using refrigerant and electricity, making them more efficient than other ...

  5. Blazed grating - Wikipedia

    en.wikipedia.org/wiki/Blazed_grating

    A special form of a blazed grating is the echelle grating. It is characterized by particularly large blaze angle (>45°). Therefore, the light hits the short legs of the triangular grating lines instead of the long legs. Echelle gratings are mostly manufactured with larger line spacing but are optimized for higher diffraction orders.

  6. Diffraction grating - Wikipedia

    en.wikipedia.org/wiki/Diffraction_grating

    A blazed diffraction grating reflecting only the green portion of the spectrum from a room's fluorescent lighting. For a diffraction grating, the relationship between the grating spacing (i.e., the distance between adjacent grating grooves or slits), the angle of the wave (light) incidence to the grating, and the diffracted wave from the grating is known as the grating equation.

  7. Central heating - Wikipedia

    en.wikipedia.org/wiki/Central_heating

    A central heating system provides warmth to a number of spaces within a building from one main source of heat. It is a component of heating, ventilation, and air conditioning (short: HVAC) systems, which can both cool and warm interior spaces. A central heating system has a furnace that converts fuel or electricity to heat.

  8. Radiant heating and cooling - Wikipedia

    en.wikipedia.org/wiki/Radiant_heating_and_cooling

    Underfloor heating systems—electric or hydronic; Wall heating systems; Radiant ceiling panels; Underfloor and wall heating systems often are called low-temperature systems. Since their heating surface is much larger than other systems, a much lower temperature is required to achieve the same level of heat transfer. This provides an improved ...

  9. Thermochemistry - Wikipedia

    en.wikipedia.org/wiki/Thermochemistry

    Endothermic reactions absorb heat, while exothermic reactions release heat. Thermochemistry coalesces the concepts of thermodynamics with the concept of energy in the form of chemical bonds. The subject commonly includes calculations of such quantities as heat capacity, heat of combustion, heat of formation, enthalpy, entropy, and free energy.