This paper deals with the optimal operation of a single removable and unreliable server in an Npolicy two-phase M/M/1 queueing system with gating, server startups and unpredictable breakdowns. Arrivals occur in batches according to a compound Poisson process and waiting customers receive batch service all at a time in the first phase and proceed to the second phase to receive individual service...

A server subject to random breakdowns and repairs offers services incoming jobs whose lengths are highly variable. checkpointing policy aiming protect against possibly lengthy recovery periods is in operation. The problem of how choose a interval order optimize performance addressed by analysing general queueing model which includes breakdowns, repairs, back-ups recoveries. Exact solutions obta...

We consider in this paper the stability of retrial queues with a versatile retrial policy. We obtain sufficient conditions for the stability by the strong coupling convergence to a stationary ergodic regime for various models of retrial queues including a model with two types of customers, a model with breakdowns of the server, a model with negative customers, and a model with batch arrivals. F...

The object of this paper is to study joint and marginal distributions of the system states at any arbitrary time moment for a single server, finite source retrial queue, in which the server can sustain breakdowns during service times. The server life times as well as the intervals between repetitions are exponentially distributed, while the repair and the service times are generally distributed...

In this paper we study the blocking time of an unreliable single-server queueing system Geo/GD/1. The service can be interrupted upon explicit or implicit breakdowns. For the successful finish of the service we use a special service discipline dividing the pure service time X (assumed to be a random variable with known distribution) in subintervals with deterministically selected time-points 0 ...