2,175 research outputs found
Waiting times in queueing networks with a single shared server
We study a queueing network with a single shared server that serves the
queues in a cyclic order. External customers arrive at the queues according to
independent Poisson processes. After completing service, a customer either
leaves the system or is routed to another queue. This model is very generic and
finds many applications in computer systems, communication networks,
manufacturing systems, and robotics. Special cases of the introduced network
include well-known polling models, tandem queues, systems with a waiting room,
multi-stage models with parallel queues, and many others. A complicating factor
of this model is that the internally rerouted customers do not arrive at the
various queues according to a Poisson process, causing standard techniques to
find waiting-time distributions to fail. In this paper we develop a new method
to obtain exact expressions for the Laplace-Stieltjes transforms of the
steady-state waiting-time distributions. This method can be applied to a wide
variety of models which lacked an analysis of the waiting-time distribution
until now
Configuration of Distributed Message Converter Systems using Performance Modeling
To find a configuration of a distributed system satisfying performance goals is a complex search problem that involves many design parameters, like hardware selection, job distribution and process configuration. Performance models are a powerful tools to analyse potential system configurations, however, their evaluation is expensive, such that only a limited number of possible configurations can be evaluated. In this paper we present a systematic method to find a satisfactory configuration with feasible effort, based on a two-step approach. First, using performance estimates a hardware configuration is determined and then the software configuration is incrementally optimized evaluating Layered Queueing Network models. We applied this method to the design of performant EDI converter systems in the financial domain, where increasing message volumes need to be handled due to the increasing importance of B2B interaction
Random Fluid Limit of an Overloaded Polling Model
In the present paper, we study the evolution of an overloaded cyclic polling
model that starts empty. Exploiting a connection with multitype branching
processes, we derive fluid asymptotics for the joint queue length process.
Under passage to the fluid dynamics, the server switches between the queues
infinitely many times in any finite time interval causing frequent oscillatory
behavior of the fluid limit in the neighborhood of zero. Moreover, the fluid
limit is random. Additionally, we suggest a method that establishes finiteness
of moments of the busy period in an M/G/1 queue.Comment: 36 pages, 2 picture
Optimizing flow rates in a queueing network with side constraints
Network Analysis;operations research
A survey of health care models that encompass multiple departments
In this survey we review quantitative health care models to illustrate the extent to which they encompass multiple hospital departments. The paper provides general overviews of the relationships that exists between major hospital departments and describes how these relationships are accounted for by researchers. We find the atomistic view of hospitals often taken by researchers is partially due to the ambiguity of patient care trajectories. To this end clinical pathways literature is reviewed to illustrate its potential for clarifying patient flows and for providing a holistic hospital perspective
The power-series algorithm applied to the shortest-queue model
Queueing Theory;operations research
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