Página 1 dos resultados de 163 itens digitais encontrados em 0.121 segundos

- Slovak University of Technology
- Hikari, Ltd.
- Hikari, Ltd
- Laboratory for Information and Decision Systems, Massachusetts Institute of Technology
- Sloan School of Management, Massachusetts Institute of Technology
- Massachusetts Institute of Technology, Laboratory for Information and Decision Systems]
- Massachusetts Institute of Technology, Operations Research Center
- Massachusetts Institute of Technology
- Universidade de Adelaide
- Universidade Cornell
- University of Cambridge; Department of Pure Mathematics and Mathematical Statistics; Emmanuel College; Statistics Laboratory
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## Queueing networks with infinite servers in each node (an application in logistics)

Fonte: Slovak University of Technology
Publicador: Slovak University of Technology

Tipo: Conferência ou Objeto de Conferência

Publicado em //2004
ENG

Relevância na Pesquisa

75.92%

After a report of results about queueing systems with infinite servers, namely
considering its busy period, we intend to build a model, using networks of queues with
infinite servers in each node, to study a two echelons repair system of a fleet of aircraft,of shipping or of trucking. The customers are the failures. And its service time is the time that goes from the instant at which they occur till the one at which they are
completely repaired. The failures repairs occur in a base or in a remote station. The
whole failures detected in the base are repaired there. Some of the failures detected in
the station are repaired in the base, and the others in the station. The results referred
above, about the infinite servers queues busy period, allow the determination of the two
echelons repair system performance measures. In this application we work over models
of Carrillo (1991) and Ferreira (1996) that we improve and complete. We will illustrate
the theory with a very simple and short numerical example.

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## Modelling and differential costs evaluation of a two echelons repair system through infinite servers nodes queuing networks

Fonte: Hikari, Ltd.
Publicador: Hikari, Ltd.

Tipo: Artigo de Revista Científica

Publicado em //2013
ENG

Relevância na Pesquisa

65.92%

After a short report of results on infinite servers queues systems, focusing on its busy period, using networks of queues with infinite servers nodes a model is constructed to study a two echelons repair system. These repair systems may be useful, for instance, in the
operation of a fleet of aircraft, of shipping or of trucks. Additionally it is shown how this model may be used in the evaluation of differential costs.

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## Stochastic processes in networks of queues with exponential service times and only one class of customers

Fonte: Hikari, Ltd
Publicador: Hikari, Ltd

Tipo: Artigo de Revista Científica

Publicado em //2014
ENG

Relevância na Pesquisa

95.96%

Two networks of queues models, presented initially by Jackson, in the open case, and
Gordon and Newell, in the closed case, stochastic processes are presented and studied in some of their details and problems. The service times are exponentially distributed and there is only one class of customers.

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## Networks of queues models with several classes of customers and exponential service times

Fonte: Hikari, Ltd
Publicador: Hikari, Ltd

Tipo: Artigo de Revista Científica

Publicado em //2015
ENG

Relevância na Pesquisa

95.99%

The main target of this paper is to present the Markov chain C that, not giving explicitly the queue lengths stationary probabilities, has the necessary information to its determination for open networks of queues with several classes of customers and exponential service times, allowing to overcome ingeniously this problem. The situation for closed networks, in the same conditions, much easier is also presented.

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## Two interfering queues in packet-radio networks

Fonte: Laboratory for Information and Decision Systems, Massachusetts Institute of Technology
Publicador: Laboratory for Information and Decision Systems, Massachusetts Institute of Technology

Formato: 33 p.; application/pdf

ENG

Relevância na Pesquisa

45.6%

M. Sidi and A. Segall.; Bibliography: p. 14.; "June, 1981."; U.S. Department of Defense contract No. N00014-75-C-1183

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## Approximations for manufacturing networks of queues with overtime

Fonte: Sloan School of Management, Massachusetts Institute of Technology
Publicador: Sloan School of Management, Massachusetts Institute of Technology

Formato: 21, [20] leaves; 1927072 bytes; application/pdf

ENG

Relevância na Pesquisa

55.6%

Gabriel R. Britan, Devanath Tirupati.; Includes bibliographical references.

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## On the large deviations behaviour of acyclic networks of G/G/1 queues

Fonte: Massachusetts Institute of Technology, Laboratory for Information and Decision Systems]
Publicador: Massachusetts Institute of Technology, Laboratory for Information and Decision Systems]

Formato: 43 p.; 2556523 bytes; application/pdf

ENG

Relevância na Pesquisa

45.6%

Dimitris Bertsimas, Ioannis Ch. Paschalidis, John N. Tsitsiklis.; Includes bibliographical references (p. 39-41).; Supported by a Presidential Young Investigator award. DDM-9158118 Supported by the ARO. DAAL03-92-G-0115 Supported by funds from the Draper Laboratory.

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## Monotone Control of Queueing and Production/Inventory Systems

Fonte: Massachusetts Institute of Technology, Operations Research Center
Publicador: Massachusetts Institute of Technology, Operations Research Center

Tipo: Trabalho em Andamento
Formato: 1214972 bytes; application/pdf

EN_US

Relevância na Pesquisa

55.59%

Weber and Stidham (1987) used submodularity to establish transition monotonicity (a service completion at one station cannot reduce the service rate at another station) for Markovian queueing networks that meet certain regularity conditions and are controlled to minimize service and queueing costs. We give an extension of monotonicity to other directions in the state space, such as arrival transitions, and to arrival routing problems. The conditions used to establish monotonicity, which deal with the boundary of the state space, are easily verified for many queueing systems. We also show that, without service costs, transition-monotone controls can be described by simple control regions and switching functions, extending earlier results. The theory is applied to production/inventory systems with holding costs at each stage and finished goods backorder costs.

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## Scheduling Networks of Queues: Heavy Traffic Analysis of a Multistation Closed Network

Fonte: Massachusetts Institute of Technology, Operations Research Center
Publicador: Massachusetts Institute of Technology, Operations Research Center

Tipo: Trabalho em Andamento
Formato: 2007841 bytes; application/pdf

EN_US

Relevância na Pesquisa

55.59%

We consider the problem of finding an optimal dynamic priority sequencing policy to maximize the mean throughput rate in a multistation, multiclass closed queueing network with general service time distributions and a general routing structure. Under balanced heavy loading conditions, this scheduling problem can be approximated by a control problem involving Brownian motion. Although a unique, closed form solution to the Brownian control problem is not derived, an analysis of the problem leads to an effective static sequencing policy, and to an approximate means of comparing the relative performance of arbitrary static policies. Three examples are given that illustrate the effectiveness of our procedure.

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## Monotone Control of Queueing and Production/Inventory Systems

Fonte: Massachusetts Institute of Technology, Operations Research Center
Publicador: Massachusetts Institute of Technology, Operations Research Center

Tipo: Trabalho em Andamento
Formato: 1214972 bytes; application/pdf

EN_US

Relevância na Pesquisa

55.59%

Weber and Stidham (1987) used submodularity to establish transition monotonicity (a service completion at one station cannot reduce the service rate at another station) for Markovian queueing networks that meet certain regularity conditions and are controlled to minimize service and queueing costs. We give an extension of monotonicity to other directions in the state space, such as arrival transitions, and to arrival routing problems. The conditions used to establish monotonicity, which deal with the boundary of the state space, are easily verified for many queueing systems. We also show that, without service costs, transition-monotone controls can be described by simple control regions and switching functions, extending earlier results. The theory is applied to production/inventory systems with holding costs at each stage and finished goods backorder costs.

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## Running in circles : packet routing on ring networks

Fonte: Massachusetts Institute of Technology
Publicador: Massachusetts Institute of Technology

Tipo: Tese de Doutorado
Formato: 156 p.; 11749248 bytes; 11749004 bytes; application/pdf; application/pdf

ENG

Relevância na Pesquisa

45.67%

I analyze packet routing on unidirectional ring networks, with an eye towards establishing bounds on the expected length of the queues. Suppose we route packets by a greedy "hot potato" protocol. If packets are inserted by a Bernoulli process and have uniform destinations around the ring, and if the nominal load is kept fixed, then I can construct an upper bound on the expected queue length per node that is independent of the size of the ring. If the packets only travel one or two steps, I can calculate the exact expected queue length for rings of any size. I also show some stability results under more general circumstances. If the packets are inserted by any ergodic hidden Markov process with nominal loads less than one, and routed by any greedy protocol, I prove that the ring is ergodic.; by William F. Bradley.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2002.; Includes bibliographical references (p. 151-154) and index.

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## Departure processes from MAP/PH/1 queues

Fonte: Universidade de Adelaide
Publicador: Universidade de Adelaide

Tipo: Tese de Doutorado
Formato: 883455 bytes; 221144 bytes; application/pdf; application/pdf

Publicado em //1999
EN

Relevância na Pesquisa

46.1%

A MAP/PH/1 queue is a queue having a Markov arrival process (MAP), and a single server with phase-type (PH -type) distributed service time. This thesis considers the departure process from these type of queues. We use matrix analytic methods, the Jordan canonical form of matrices, non-linear filtering and approximation techniques. The departure process of a queue is important in the analysis of networks of queues, as it may be the arrival process to another queue in the network. If a simple description were to exist for a departure process, the analysis of at least feed-forward networks of these queues would then be analytically tractable.
Chapter 1 is an introduction to some of the literature and ideas surrounding the departure process from MAP/PH/1 queues.
Chapter 2 sets up the basic notation and establishes some results which are used throughout the thesis. It contains a preliminary consideration of PH -type distributions, PH -renewal processes, MAP s, MAP/PH/1 queues, non-linear filtering and the Jordan canonical form.
Chapter 3 is an expansion of "The Output process of an MMPP/M/1 queue", where the question of whether a MAP description can exist for the departure process of a non-trivial MAP/M/1 queue is considered. In a 1994 paper...

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## Optimization of Multiclass Queueing Networks: Polyhedral and Nonlinear Characterizations of Achievable Performance

Tipo: Trabalho em Andamento
Formato: 2800138 bytes; application/pdf

EN_US

Relevância na Pesquisa

45.78%

We consider open and closed multiclass queueing networks with Poisson arrivals (in open networks), exponentially distributed class dependent service times, and with class dependent deterministic or probabilistic routing. For open networks, the performance objective is to minimize, over all sequencing and routing policies, a weighted sum of the expected response times of different classes. Using a powerful technique involving quadratic or higher order potential functions, we propose variants of a method to derive polyhedral and nonlinear spaces which contain the entire set of achievable response times under stable and preemptive scheduling policies. By optimizing over these spaces, we obtain lower bounds on achievable performance. In particular, we obtain a sequence of progressively more complicated nonlinear approximations (relaxations) which are progressively closer to the exact achievable space. In the special case of single station networks (multiclass queues and Klimov's model) and homogenous multiclass networks, our characterization gives exactly the achievable region. Consequently, the proposed method can be viewed as the natural extension of conservation laws to multiclass queueing networks. For closed networks, the performance objective is to maximize throughput. We similarly find polyhedral and nonlinear spaces that include the performance space and by maximizing over these spaces we obtain an upper bound on the optimal throughput. We check the tightness of our bounds by simulating heuristic scheduling policies for simple open networks and we find that the first order approximation of our method is at least as good as simulation-based existing methods. In terms of computational complexity and in contrast to simulation-based existing methods...

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## Modeling Travel Times in Dynamic Transportation Networks; A Fluid Dynamics Approach

Tipo: Trabalho em Andamento
Formato: 2043933 bytes; application/pdf

EN_US

Relevância na Pesquisa

45.67%

In this paper, we take a fluid dynamics approach to determine the travel time in traversing a network's link. We propose a general model for travel time functions that utilizes fluid dynamics laws for compressible flow to capture a variety of flow patterns such as the formation and dissipation of queues, drivers' response to upstream congestion or decongestion and drivers' reaction time. We examine two variants of the model, in the case of separable velocity functions, which gives rise to two families of travel time functions for the problem; a polynomial and an exponential family. We analyze these travel time functions and examine several special cases. Our investigation also extends to the case of non-separable velocity functions starting with an analysis of the interaction between two links, and then extending it to the general case of acyclic networks.

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## Strong Stationary Duality for M\"obius Monotone Markov Chains: Unreliable Networks

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 01/01/2011

Relevância na Pesquisa

45.67%

For Markov chains with a partially ordered finite state space we show strong
stationary duality under the condition of M\"obius monotonicity of the chain.
We show relations of M\"obius monotonicity to other definitions of monotone
chains. We give examples of dual chains in this context which have transitions
only upwards. We illustrate general theory by an analysis of nonsymmetric
random walks on the cube with an application to networks of queues.

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## Dynamics of Jackson networks: perturbation theory

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 13/08/2007

Relevância na Pesquisa

45.68%

We introduce a new formalism for dealing with networks of queues. The
formalism is based on the Doi-Peliti second quantization method for reaction
diffusion systems. As a demonstration of the method's utility we compute
perturbatively the different time busy-busy correlations between two servers in
a Jackson network.; Comment: 15 pages, 1 figure

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## Throughput Optimal Scheduling Policies in Networks of Interacting Queues

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

45.84%

This report considers a fairly general model of constrained queuing networks
that allows us to represent both MMBP (Markov Modulated Bernoulli Processes)
arrivals and time-varying service constraints. We derive a set of sufficient
conditions for throughput optimality of scheduling policies that encompass and
generalize all the previously obtained results in the field. This leads to the
definition of new classes of (non diagonal) throughput optimal scheduling
policies. We prove the stability of queues by extending the traditional
Lyapunov drift criteria methodology.

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## Bayesian inference for queueing networks and modeling of internet services

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

45.87%

#Statistics - Machine Learning#Computer Science - Networking and Internet Architecture#Computer Science - Performance#Statistics - Applications#Statistics - Computation

Modern Internet services, such as those at Google, Yahoo!, and Amazon, handle
billions of requests per day on clusters of thousands of computers. Because
these services operate under strict performance requirements, a statistical
understanding of their performance is of great practical interest. Such
services are modeled by networks of queues, where each queue models one of the
computers in the system. A key challenge is that the data are incomplete,
because recording detailed information about every request to a heavily used
system can require unacceptable overhead. In this paper we develop a Bayesian
perspective on queueing models in which the arrival and departure times that
are not observed are treated as latent variables. Underlying this viewpoint is
the observation that a queueing model defines a deterministic transformation
between the data and a set of independent variables called the service times.
With this viewpoint in hand, we sample from the posterior distribution over
missing data and model parameters using Markov chain Monte Carlo. We evaluate
our framework on data from a benchmark Web application. We also present a
simple technique for selection among nested queueing models. We are unaware of
any previous work that considers inference in networks of queues in the
presence of missing data.; Comment: Published in at http://dx.doi.org/10.1214/10-AOAS392 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org)

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## Stability and Capacity Regions or Discrete Time Queueing Networks

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 17/03/2010

Relevância na Pesquisa

45.84%

We consider stability and network capacity in discrete time queueing systems.
Relationships between four common notions of stability are described.
Specifically, we consider rate stability, mean rate stability, steady state
stability, and strong stability. We then consider networks of queues with
random events and control actions that can be implemented over time to affect
arrivals and service at the queues. The control actions also generate a vector
of additional network attributes. We characterize the network capacity region,
being the closure of the set of all rate vectors that can be supported subject
to network stability and to additional time average attribute constraints. We
show that (under mild technical assumptions) the capacity region is the same
under all four stability definitions. Our capacity achievability proof uses the
drift-plus-penalty method of Lyapunov optimization, and provides full details
for the case when network states obey a decaying memory property, which holds
for finite state ergodic systems and more general systems.; Comment: 19 pages

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## Collaborating queues: large service network and a limit order book

Fonte: University of Cambridge; Department of Pure Mathematics and Mathematical Statistics; Emmanuel College; Statistics Laboratory
Publicador: University of Cambridge; Department of Pure Mathematics and Mathematical Statistics; Emmanuel College; Statistics Laboratory

Tipo: Thesis; doctoral; PhD

EN

Relevância na Pesquisa

45.84%

E-thesis pagination differs from hardbound copy kept in the Manuscripts Department, Cambridge University Library.; We analyse the steady-state behaviour of two different models with collaborating queues: that is, models in which "customers" can be served by many types of "servers", and "servers" can process many types of "customers".
The first example is a large-scale service system, such as a call centre. Collaboration
is the result of cross-trained staff attending to several different types of incoming calls. We first examine a load-balancing policy, which aims to keep servers in different pools equally busy. Although the policy behaves order-optimally over fixed time horizons, we show that the steady-state distribution may fail to be tight on the diffusion scale. That is, in a family of ever-larger networks whose arrival rates grow as O(r) (where r is a scaling parameter growing to infinity), the sequence of steady-state deviations from equilibrium scaled down by sqrt(r) is not tight. We then propose a different policy, for which we show that the sequence of invariant distributions is tight on the r^(1/2+epsilon) scale, for any epsilon > 0. For this policy we conjecture that tightness holds on the diffusion scale as well.
The second example models a limit order book...

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