Inter-individual differences in the phase of the endogenous circadian rhythms have been established. Individuals with early circadian phase are called morning types; those with late circadian phase are evening types. The Horne and Ostberg Morningness-Eveningness Questionnaire (MEQ) is the most frequently used to assess individual chronotype. The distribution of MEQ scores is likely to be biased...

The author presents performance analysis of a single buffer multiple-queue system. Four different types of service disciplines (i.e., non-preemptive, pre-emptive repeat different, state dependent random polling and globally gated) are analyzed. His model includes correlated input process and three different types of nonproductive time (i.e., switchover, vacation and idle time). Special cases of...

We consider a stationary multi-class FIFO M/G/1 queue with exponential working vacations, where a server works at two different processing rates. There are K classes of customers, and the arrival rates and the distributions of the amount of service requirements of arriving customers depend on both their customer classes and the server state. When the system becomes empty, the server takes a wor...

This paper considers a single-server retrial queue with constant retrial rate and batch arrivals, where an unreliable server may take an additional optional vacation after the first essential vacation. Customers arrive at the system according to a compound Poisson process, and they are served immediately if the server is available; otherwise, they will enter a retrial orbit and form a single wa...

We derive performance measures for burst arrival (e.g. messages of variable length packets) M / G / 1 queues with server vacations, controlled by the, so called, Randomly Timed Gated (RTG) protocol, operating as follows : Whenever the server returns from a ( general-type ) vacation and initiates a busy period, a Timer with random duration T is activated. If the server empties the queue before t...

this paper analyzes a renewal input  working vacations queue with change over times and bernoulli schedulevacation interruption under (a,c,b) policy.the service and vacation times are exponentially distributed.the server begins service if there are at least c units in the queue and the service takes place in batches with a minimum of size a and a maximum of size b (a

We study an M/M/2 queueing system with two heterogeneous servers under a variant vacation policy, where the two servers may take together at most J vacations when the system is empty. A quasi-birth-and-death process is formulated to analyze the system. We obtain the explicit expressions of the stationary distribution of the system size and the mean system size. We also show that the number of v...

In this paper we propose the general bulk service queueing model for FM/M(a,b)/1/MWV/Br. The batches are served according to FCFS discipline. In which arrival rate, vacation parameter, service rate for busy period, and for vacation period are all considered as trapezoidal fuzzy numbers. The basic idea is to convert all these fuzzy numbers into crisp values by applying Robust ranking Technique. ...