This study is concerned with the performance modeling of a fault tolerant system consisting of operating units supported by a combination of warm and cold spares. The on-line as well as warm standby units are subject to failures and are send for the repair to a repair facility having single repairman which is prone to failure. If the failed unit is not detected, the system enters into an unsafe...

The aim of this paper is to provide a more realistic description of priority-discipline queueing models by using Fuzzy Set Theory. It develops and optimizes two fuzzy queueing models with priority-discipline, a model with nonpreemptive priorities system and a model with preemptive priorities system, denoted by M̃i /M̃i /1 and M̃i /Fi /1. The first symbol is for a queueing system where arrivals and...

In the today’s Internet and TCP/IPnetworks, the queueing of packets is commonly implemented using the protocol FIFO (First In First Out). Unfortunately, FIFO performs poorly in the Adversarial Queueing Theory. Other queueing strategies are researched in this model and better results are performed by alternative queueing strategies, e.g. LIS (Longest In System). This article introduces a new que...

The paper is designated to the analysis of queueing systems, arising in the network theory and communications theory (called multiphase queueing systems, tandem queues or series of queueing systems). Also we note that multiphase queueing systems can be useful for modelling practical multi-stage service systems in a variety of disciplines, especially on manufacturing (assembly lines), computer n...

In the queueing theory we usually ignore the fact that utility server is often a technical device and its breakdown can occur. Common analytic models (see for example in [1] or [2]) assume that the server works reliably without failures causing its deficit. If failures of the server occur often and we would use an analytic model of reliable queueing system for modeling studied system, reached o...

Traffic patterns generated by multimedia services are different from traditional Poisson traffic. It has been shown in numerous studies that multimedia network traffic exhibits self-similarity and burstiness over a large range of time-scales. The area of wireless IP traffic modeling for the purpose of providing assured QoS to the end-user is still immature and the majority of existing work is b...

In this paper we show that the waiting and the sojourn times of a customer in a single-stage, multiple-server, G / G /c queueing system are increasing and starshaped with respect to the mean service time. Usefulness of this result in the design of the optimal service speed in the G / G /c queueing system is also demonstrated. SECOND-ORDER PROPERTIES; SINGLE-STAGE QUEUEING SYSTEMS; STOCHASTIC ST...