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The name honors the French Engineer Henry Darcy who first described the flow of water through sand filters for potable water supply. Permeability values for most materials commonly range typically from a fraction to several thousand millidarcys. The unit of square centimetre (cm 2) is also sometimes used (1 cm 2 = 10 −4 m 2 ≈ 10 8 d).
The first model to use this approach was the Bernal–Fowler model published in 1933, [21] which may also be the earliest water model. However, the BF model doesn't reproduce well the bulk properties of water, such as density and heat of vaporization , and is thus of historical interest only.
Thermally processed material is usually totally amorphous, [7] and as a result is highly transparent to visible light, with better light transmission than many kinds of glass. Polycarbonate has a glass transition temperature of about 147 °C (297 °F), [8] so it softens gradually above this point and flows above about 155 °C (311 °F). [9]
A density meter (densimeter) is a device which measures the density of an object or material. Density is usually abbreviated as either ρ {\displaystyle \rho } or D {\displaystyle D} . Typically, density either has the units of k g / m 3 {\displaystyle kg/m^{3}} or l b / f t 3 {\displaystyle lb/ft^{3}} .
ASTM F1249 - Standard Test Method for Water Vapor Transmission Rate Through Plastic Film and Sheeting Using a Modulated Infrared Sensor ASTM F2298- Standard Test Methods for Water Vapor Diffusion Resistance and Air Flow Resistance of Clothing Materials Using the Dynamic Moisture Permeation Cell
Scale models offer a useful approximation of physical or chemical processes at a size that allows for greater ease of visualization. [1] The model may be created in one (core, column), two (plan, profile), or three dimensions, and can be designed to represent a variety of specific initial and boundary conditions as needed to answer a question.
The calculation of glass properties allows "fine-tuning" of desired material characteristics, e.g., the refractive index. [1]The calculation of glass properties (glass modeling) is used to predict glass properties of interest or glass behavior under certain conditions (e.g., during production) without experimental investigation, based on past data and experience, with the intention to save ...
This approximation could be made more and more accurate at even vanishingly small shear rates by means of a material parameter that controls the exponential growth of stress. Thus, a new impetus was given in 1987 with the publication by Papanastasiou [4] of such a modification of the Bingham model with an exponential stress-growth term. The new ...