Search results
Results from the WOW.Com Content Network
In an optical fiber, the material dispersion coefficient, M(λ), characterizes the amount of pulse broadening by material dispersion per unit length of fiber and per unit of spectral width. It is usually expressed in picoseconds per ( nanometre · kilometre ).
A dispersion is a system in which distributed particles of one material are dispersed in a continuous phase of another material. The two phases may be in the same or different states of matter . Dispersions are classified in a number of different ways, including how large the particles are in relation to the particles of the continuous phase ...
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
The diffusion coefficient is the coefficient in the Fick's first law = /, where J is the diffusion flux (amount of substance) per unit area per unit time, n (for ideal mixtures) is the concentration, x is the position [length].
The self-diffusion coefficient of neat water is: 2.299·10 −9 m 2 ·s −1 at 25 °C and 1.261·10 −9 m 2 ·s −1 at 4 °C. [2] Chemical diffusion occurs in a presence of concentration (or chemical potential) gradient and it results in net transport of mass. This is the process described by the diffusion equation.
This formula generalizes the one in the previous section for homogeneous media and includes both waveguide dispersion and material dispersion. The reason for defining the dispersion in this way is that | D | is the (asymptotic) temporal pulse spreading Δ t per unit bandwidth Δ λ per unit distance travelled, commonly reported in ps /( nm ⋅ ...
In materials science, dispersion is the fraction of atoms of a material exposed to the surface. In general, D = N S / N , where D is the dispersion, N S is the number of surface atoms and N T is the total number of atoms of the material. [ 1 ]
A polymer material is denoted by the term disperse, or non-uniform, if its chain lengths vary over a wide range of molecular masses. This is characteristic of man-made polymers. [ 7 ] Natural organic matter produced by the decomposition of plants and wood debris in soils ( humic substances ) also has a pronounced polydispersed character.