On an optimal strategy for activating a second or a stand-by channel in a single line bulk service system

The paper is concerned with an optimal switching of a second or a stand-by instrument into a single line bulk service system. Two cases of a stand-by instrument are taken up, a symmetrical one and a nonsymmetrical one. It is proved that the optimal strategy of serviceing by the stand-by instrument belongs to the class of strategies where the stand-by instrument is connected and disconnected with the same length of the queue. The optimal queue length is found with which the global minimum of the optimality criterion is obtained.