A membership function solution to multiple-server fuzzy queues

Abstract

Problems of multiple-server fuzzy queues are often encountered in service industry, such as in hospital clinics. In this paper, a membership function of the performance measure of multiple-server fuzzy queues with the arrival rate and service rate are fuzzy numbers is derived, in which /spl alpha/-cut and Zadeh's extension principle are applied to transform multiple-server fuzzy queues to a family of conversional multiple-server queues, and a pair of parametric programs is formulated to calculate the upper and lower bounds of the performance measure. As /spl alpha/ varies, the membership function of the expected sojourn time per patient in the clinic with 2-server fuzzy queues is solved in the presented numerical example. Since the performance measures are expressed by membership functions rather than by crisp values, more information is provided for managerial decision-making in hospitals.