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Boltsman's distribution.
The Boltzmann distribution for the fractional number of particles Ni / N occupying a set of states i possessing energy Ei is:
where 
is the Boltzmann constant, T is temperature (assumed to be a well-defined quantity), 
is the degeneracy (meaning, the number of levels having energy 
; sometimes, the more general 'states' are used instead of levels, to avoid using degeneracy in the equation), N is the total number of particles and Z(T) is the partition function.
Diffusion.
Diffusion is one of several transport phenomena that occur in nature. A distinguishing feature of diffusion is that it results in mixing or mass transport without requiring bulk motion. Thus, diffusion should not be confused with convection or advection, which are other transport mechanisms that use bulk motion to move particles from one place to another.
Internal friction.
Internal friction is the force resisting motion between the elements making up a solid material while it undergoes plastic deformation.
Plastic deformation in solids is an irreversible change in the internal molecular structure of an object. This change may be due to either (or both) an applied force or a change in temperature. The change of an object's shape is called strain. The force causing it is called stress. Stress does not necessarily cause permanent change. As deformation occurs, internal forces oppose the applied force. If the applied stress is not too large these opposing forces may completely resist the applied force, allowing the object to assume a new equilibrium state and to return to its original shape when the force is removed. This is what is known in the literature as elastic deformation (or elasticity). Larger forces in excess of the elastic limit may cause a permanent (irreversible) deformation of the object. This is what is known as plastic deformation.
Heat conduction.
In heat transfer, conduction (or heat conduction) is the transfer of heat energy by microscopic diffusion and collisions of particles or quasi-particles within a body due to atemperature gradient
. The microscopically diffusing and colliding objects include molecules, electrons, atoms, and phonons. They transfer microscopically disorganized kinetic and potential energy, which are jointly known as internal energy. Conduction takes place in all forms of ponderable matter, such as solids, liquids, gases and plasmas.By conduction, as well as by thermal radiation, heat spontaneously flows from a body at a higher temperature to a body at a lower temperature. In the absence of external driving fluxes, temperature differences, over time, approach thermal equilibrium.