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  2. Darcy (unit) - Wikipedia

    en.wikipedia.org/wiki/Darcy_(unit)

    The darcy is referenced to a mixture of unit systems. A medium with a permeability of 1 darcy permits a flow of 1 cm 3 /s of a fluid with viscosity 1 cP (1 mPa·s) under a pressure gradient of 1 atm/cm acting across an area of 1 cm 2. Typical values of permeability range as high as 100,000 darcys for gravel, to less than 0.01 microdarcy for ...

  3. Orders of magnitude (pressure) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(pressure)

    +1.9 psi High air pressure for human lung, measured for trumpet player making staccato high notes [48] < +16 kPa +2.3 psi Systolic blood pressure in a healthy adult while at rest (< 120 mmHg) (gauge pressure) [44] +19.3 kPa +2.8 psi High end of lung pressure, exertable without injury by a healthy person for brief times [citation needed] +34 kPa ...

  4. System equivalence - Wikipedia

    en.wikipedia.org/wiki/System_equivalence

    Equivalent systems can be used to change large and expensive mechanical, thermal, and fluid systems into a simple, cheaper electrical system. Then the electrical system can be analyzed to validate that the system dynamics will work as designed. This is a preliminary inexpensive way for engineers to test that their complex system performs the ...

  5. Vacuum - Wikipedia

    en.wikipedia.org/wiki/Vacuum

    Ultra-high vacuum systems are usually baked, preferably under vacuum, to temporarily raise the vapour pressure of all outgassing materials and boil them off. Once the bulk of the outgassing materials are boiled off and evacuated, the system may be cooled to lower vapour pressures and minimize residual outgassing during actual operation.

  6. Pressure measurement - Wikipedia

    en.wikipedia.org/wiki/Pressure_measurement

    In the cgs system the unit of pressure was the barye (ba), equal to 1 dyn·cm −2. In the mts system, the unit of pressure was the pieze, equal to 1 sthene per square metre. Many other hybrid units are used such as mmHg/cm 2 or grams-force/cm 2 (sometimes as kg/cm 2 without properly identifying the force units). Using the names kilogram, gram ...

  7. Gaussian units - Wikipedia

    en.wikipedia.org/wiki/Gaussian_units

    One difference between the Gaussian and SI systems is in the factor 4π in various formulas that relate the quantities that they define. With SI electromagnetic units, called rationalized, [3] [4] Maxwell's equations have no explicit factors of 4π in the formulae, whereas the inverse-square force laws – Coulomb's law and the Biot–Savart law – do have a factor of 4π attached to the r 2.

  8. Raoult's law - Wikipedia

    en.wikipedia.org/wiki/Raoult's_law

    Raoult's law (/ ˈ r ɑː uː l z / law) is a relation of physical chemistry, with implications in thermodynamics.Proposed by French chemist François-Marie Raoult in 1887, [1] [2] it states that the partial pressure of each component of an ideal mixture of liquids is equal to the vapor pressure of the pure component (liquid or solid) multiplied by its mole fraction in the mixture.

  9. Gell-Mann and Low theorem - Wikipedia

    en.wikipedia.org/wiki/Gell-Mann_and_Low_theorem

    The theorem is useful because, among other things, by relating the ground state of the interacting theory to its non-interacting ground state, it allows one to express Green's functions (which are defined as expectation values of Heisenberg-picture fields in the interacting vacuum) as expectation values of interaction picture fields in the non ...