The degree of variation in the propagation directions of sound waves over the volume of a sound field.

A method of producing a junction by difusing an impurity metal into a semiconductor at a high temperature.

The conversion of air velocity into static pressure in the diffuser casing of a centrifugal fan, resulting from increases in the radius of the air spin and in area.

The exchange of fluid parcels (and hence the transport of conservative properties) between regions in space, in the apparently random motions of the parcels on a scale too small to be treated by the equations of motion; the diffusion of momentum (viscosity), vorticity, water vapor, heat (conduction), and gaseous components of the atmospheric mixture have been studied extensively.

1. The distribution of incident light by reflection.

2. Transmission of light through a translucent material.

1. The spontaneous movement and scattering of particles (atoms and molecules), of liquids, gases, and solids.

2. In particular, the macroscopic motion of the components of a system of fluids that is driven by differences in concentration.

1. The actual transport of mass, in the form of discrete atoms, through the lattice of a crystalline solid.

2. The movement of carriers in a semiconductor.