Grain movement

Typical scope Seed purity Grain movements, IP-systems or channeling Processed food or feed... 

Movement of particles into and out of pores in packing grains Movement of parlldes into and out of regions having low fluid velocity external to the grains... 

Bagnold (1941) determined two threshold values of p, a lower threshold value for which grain movement is first detected (P = 0.01), and an impact threshold at which saltation would be maintained (P = 0.0064). Hence the shear stress required near the surface to sustain an... 

Cataclasis the fault movement has destroyed the rock matrix close to the fault plane. Individual quartz grains have been ground up creating a seal comprising of rock flour . 

Diffusion is based mainly on the diffusion of vacancies grain boundaries may act as sinks for these vacancies. This vacancy movement and annihilation cause the porosity of the powder compact to decrease during sintering. 

In addition, a significant amount of fine catalyst dust is produced in FCCUs as a result of the constant movement of the catalyst grains against each other. Much of this dust, consisting primarily of alumina and relatively small amounts of nickel, is carried with the carbon monoxide strewn to the carbon monoxide burner. 

More distinct regularities observed in the Al-phase allow us to distinguish dislocation slips expressed by the movement of orientation peaks along the fibres from the grain boundary sliding responsible for the smoothing effects and thus for the superplasticity of the alloy... 

The physical process of melt ascent during two-phase flow models is typically based on the separation of melt and solid described by Darcy s Law modified for a buoyancy driving force. The melt velocity depends on the permeability and pressure gradients but the actual microscopic distribution of the melt (on grain boundaries or in veins) is left unspecified. The creation of disequilibria only requires movement of the fluid relative to the solid. 

Sagan, C. E. and Lengemann, F. W. (1973). The retention and movement of cerium-141 in the gastrointestinal tract of adult rats irradiated with 800 R and fed grain-based or milk diets, Radiat. Res. 53,480. 

In addition to movement of lattice members within a crystal, it is also possible for there to be motion of members along the surface. Consequently, this type of diffusion is known as surface diffusion. Because crystals often have grain boundaries, cracks, dislocations, and pores, there can be motion of lattice members along and within these extended defects. 

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