DIFFUSION EQUATION FOR GIX G/R MACHINE INTERFERENCE PROBLEM WITH SPARE MACHINES/

A diffusion approximation technique is developed for an (m, M) machine repair system containing M identical machines under the care of r rep airmen provided N spare machines. The machines may fail in groups of r andom size. As soon as machines fail, they are replaced by spare machi nes, provided spare machines are available. By approximating the discr ete flow of failed machines by a continuous one, the analysis is carri ed out by using the diffusion approximation technique. We have obtaine d expressions for various measures of performance in terms of means an d variances of inter-failure, repair and group size distributions. We have also discussed the modified boundary conditions required to impro ve the approximation.