Performance analysis of time-dependent queueing systems: survey and classification

Many queueing systems are subject to time-dependent changes in system parameters, such as the arrival rate or number of servers. Examples include time-dependent call volumes and agents at inbound call centers, time-varying air traffic at airports, time-dependent truck arrival rates at seaports, and cyclic message volumes in computer systems.There are several approaches for the performance analysis of queueing systems with deterministic parameter changes over time. In this survey, we develop a classification scheme that groups these approaches according to their underlying key ideas into (i) numerical and analytical solutions,(ii)approaches based on models with piecewise constant parameters, and (iii) approaches based on mod-ified system characteristics. Additionally, we identify links between the different approaches and provide a survey of applications that are categorized into service, road and air traffic, and IT systems

Conditional dynamics of non-Markovian, infinite-server queues

Thesis (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2005.Includes bibliographical references (p. 75-79).We study the transient dynamics of a partially observed, infinite server queue fed with a Poisson arrival process whose controlled rate is changed at discrete points in time. More specifically, we define a state that incorporates partial information from the history of the process and write analytical formula for the dynamics of the system (state transition probabilities). Moreover, we develop an approximation method that makes the state finite-dimensional, and introduce techniques to further reduce the dimension of the state. This method could thus enable the formulation of tractable DPs in the future.by Theophane Weber.S.M

Analysis of buffer allocations in time-dependent and stochastic flow lines

This thesis reviews and classifies the literature on the Buffer Allocation Problem under steady-state conditions and on performance evaluation approaches for queueing systems with time-dependent parameters. Subsequently, new performance evaluation approaches are developed. Finally, a local search algorithm for the derivation of time-dependent buffer allocations is proposed. The algorithm is based on numerically observed monotonicity properties of the system performance in the time-dependent buffer allocations. Numerical examples illustrate that time-dependent buffer allocations represent an adequate way of minimizing the average WIP in the flow line while achieving a desired service level

Model for estimating and comparing the risk of occurrence accidents and incidents on the level crossings

U radu je određen matematički model sa ciljem proračuna maksimalnog rizika i utvrđivanja pouzdanosti putno-pružnih prelaza. U definisanom inženjerskom okviru, od determinističke do stohastičke granice apstraktnog broja nesreća i nezgoda, nalazi se  proporcija za estimaciju i komparaciju rizika od nastanka nezgoda i nesreća na putno-pružnim prelazima zasnovana na realnim događajima. Moguće je utvrđivanje nivoa bezbednosti za svaki putni prelaz pojedinačno, što predstavlja originalni doprinos u istraživanjima bezbednosti na mestima ukrštaja železničkog i drumskog saobraćaja.This paper is determined a mathematical model to calculate the maximum risk and determine the reliability of level crossings. In the strongly defined engineering framework, from the deterministic to the stochastic limit of the number of theoretical accidents and incidents, there is a proportion for estimating and comparing the risk of accidents and incidents at level crossings based on real occurrences. It is possible to determine the level of safety for each railroad crossing individually, which is an original contribution to safety research at the intersections of railway and road traffi