With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Dogstar (band) released an album.
text_B: Knudsen diffusion is a means of diffusion that occurs when the scale length of a system is comparable to or smaller than the mean free path of the particles involved .. diffusion. diffusion. mean free path. mean free path. An example of this is in a long pore with a narrow diameter -LRB- 2 -- 50 nm -RRB- because molecules frequently collide with the pore wall .. Consider the diffusion of gas molecules through very small capillary pores .. diffusion. diffusion. If the pore diameter is smaller than the mean free path of the diffusing gas molecules and the density of the gas is low , the gas molecules collide with the pore walls more frequently than with each other .. mean free path. mean free path. pore diameter. Porosity. This process is known as Knudsen flow or Knudsen diffusion .. diffusion. diffusion. The Knudsen number is a good measure of the relative importance of Knudsen diffusion .. diffusion. diffusion. Knudsen number. Knudsen number. A Knudsen number much greater than one indicates Knudsen diffusion is important .. diffusion. diffusion. Knudsen number. Knudsen number. In practice , Knudsen diffusion applies only to gases because the mean free path for molecules in the liquid state is very small , typically near the diameter of the molecule itself .. diffusion. diffusion. mean free path. mean free path. The diffusivity for Knudsen diffusion is obtained from the self-diffusion coefficient derived from the kinetic theory of gases  :. diffusion. diffusion. or for diffusivity of species j in a mixture. For Knudsen diffusion , path length λ is replaced with pore diameter , as species A is now more likely to collide with the pore wall as opposed with another molecule .. diffusion. diffusion. pore diameter. Porosity. The Knudsen diffusivity for diffusing species A , is thus. where is the gas constant -LRB- 8.3144 J  /  -LRB- mol · K -RRB- in SI units -RRB- , molecular mass is expressed in units of kg / mol , and temperature T has units of K. Knudsen diffusivity thus depends on the pore diameter , species molecular mass and temperature .. pore diameter. Porosity. kelvin. Generally , the Knudsen process is significant only at low pressure and small pore diameter .. pore diameter. Porosity. However there may be instances where both Knudsen diffusion and molecular diffusion are important .. diffusion. diffusion. The effective diffusivity of species A in a binary mixture of A and B , is determined by. where. For cases where α = 0 or where is close to zero , the equation reduces to
not_related.