TRANSPORT AND CONDUCTION IN RANDOM-SYSTEMS

The authors discuss the use of the effective medium approximation (EMA) for the calculation of the macroscopic properties of a microscopically disordered system. The discussion is restricted to the case of a periodic lattice with disorder in transport properties at the level of individual bonds. The authors review recent applications of the EMA to disordered rate equations (master equations) and show how the basic formalism extends to a class of disordered integrodifference equations (generalized master equations) and to transport processes in which loss of the mobile species from the system is possible. In each case the macroscopic system properties, obtained by smoothing out spatial disorder, exhibit time-correlation or memory effects.