Motivated by models of queues with server vacations, we consider a Le ́vy process modified to have random jumps at arbitrary stopping times. The extra jumps can counteract a drift in the Le ́vy process so that the overall Le ́vy process with secondary jump input, can have a proper limiting distribution. For example, the workload process in an M/G/1 queue with a server vacation each time the server...

This paper considers queues with server vacations, but departs from the traditional setting in two ways: (i) the queueing model is driven by Lévy processes rather than just compound Poisson processes; (ii) the vacation lengths depend on the length of the server’s preceding busy period. Regarding the former point: the Lévy process active during the busy period is assumed to have no negative jump...

The hypothesis that the vacation-study-expectancy scholar regime produces most of the monthly rhythm of the age at menarche (AaM) was tested. Studies on monthly menarche incidence (MI) refuted climatic factors as a main factor in this rhythm, and indicated that the main factor of this rhythm is the succession of expectancies of study (Stu-months) or vacation (Vac-months) months within a year. T...

We consider in this paper the optimal open-loop control of vacations in queueing systems. The controller has to take actions without state information. We rst consider the case of a single queue, in which the question is when should vacations be taken so as to minimize, in some general sense, workloads and waiting times. We then consider the case of several queues, in which service of one queue...

We consider a batch arrival queueing system with two phases of service, feedback and K optional vacations under a classical retrial policy. At the arrival epoch, if the server is busy the whole batch joins the orbit. Whereas if the server is free, then one of the arriving customer starts its service immediately and the rest joins the orbit. For each customer, the server provides two phases of s...

This paper addresses web object size which is one of important performance measures and affects to service time in multiple access environment. Since packets arrive according to Poission distribution and web service time has arbitrary distribution, M/G/1 model can be used to describe the behavior of the web server system. In the time division multiplexing (TDM), we can use M/D/1 with vacations ...

The delayed delivery of the AIRBUS A380© demonstrates the challenges to be faced in the field of cross-company collaboration today. On the one hand, available CWE platforms are used insufficiently. On the other hand, they do not yet support collaboration in a completely adequate way. This paper illustrates the current state of CWE practice by way of a sample company, its internal and external c...

The IP Multimedia Subsystem is an architectural framework for delivering multimedia services over an Internet Protocol (IP) network. Originally, it was specified for wireless networks, but has since evolved to incorporate fixed line access as well. It forms part of a Next Generation Network (NGN) which is defined as a packet-based network where the service functionality is independent of the un...

In this paper, a bulk arrival retrial queueing model with two phases of service symbolically denoted by M/(G1,G2)/1 has been discussed under Bernoulli vacation schedule to explore main ly its steady state behaviour using maximum entropy principle (MEP). We consider that customers arrive in batches according to Poisson distribution and a single server of the system provides his services in two p...