Person:
López Herrero, María Jesús

First Name

María Jesús

Last Name

López Herrero

URI

https://hdl.handle.net/20.500.14352/77420

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Estudios estadísticos

Department

Estadística y Ciencia de los Datos

Area

Estadística e Investigación Operativa

Identifiers

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Now showing 1 - 10 of 27

The SIS and SIR stochastic epidemic models: A maximum entropy approach
(Theoretical population biology, 2011) Artalejo Rodríguez, Jesús Manuel; López Herrero, María Jesús
We analyze the dynamics of infectious disease spread by formulating the maximum entropy (ME) solutions of the susceptible-infected-susceptible (SIS) and the susceptible-infected-removed (SIR) stochastic models. Several scenarios providing helpful insight into the use of the ME formalism for epidemic modeling are identified. The ME results are illustrated with respect to several descriptors, including the number of recovered individuals and the time to extinction. An application to infectious data from outbreaks of extended spectrum beta lactamase (ESBL) in a hospital is also considered.
Stochastic epidemic models: new behavioral indicators of the disease spreading
(Applied Mathematical Modelling, 2014) Artalejo Rodríguez, Jesús Manuel; López Herrero, María Jesús
The purpose of this paper is to propose new indicators of the dynamics of infectious disease spread in stochastic epidemic models, including both global system-oriented descriptors (e.g. the final size measured as the number of individuals infected on a least one occasion during an outbreak) and individual-oriented descriptors (e.g. the time to reach an individual run of infections). We focus on birth-and-death models and the basic SIR epidemic model but the methodology remains valid for other nonlinear stochastic epidemic models. The theory is illustrated by numerical experiments which demonstrate that the proposed behavioral indicators can be applied efficiently
On the single server retrial queue with balking
(INFOR. Information systems and operational research, 2000) Artalejo Rodríguez, Jesús Manuel; López Herrero, María Jesús
We are concerned with the M/G/1 retrial queue with balking. The ergodicity condition is first investigated making use Of classical mean drift criteria. The limiting distribution of the number of customers in the system is determined with the help of a recursive approach based on the theory of regenerative processes. Many closed form expressions are obtained when we reduce to the M/M/1 queue for some representative balking policies.
Algorithmic analysis of the maximum queue length in a busy period for the M/M/c retrial queue
(INFORMS Journal on Computing, 2007) Artalejo Rodríguez, Jesús Manuel; Economou, A.; López Herrero, María Jesús
This paper deals with the maximum number of customers in orbit (and in the system) during a busy period for the M/M/c retrial queue. Determining the distribution for the maximum number of customers in orbit is reduced to computation of certain absorption probabilities. By reducing to the single-server case we arrive at a closed analytic formula. For the multi-server case we develop an efficient algorithmic procedure for computation of this distribution by exploiting the special block-tridiagonal structure of the system. Numerical results illustrate the efficiency of the method and reveal interesting facts concerning the behavior of the M/M/c retrial queue.
Low retrial analysis of multiserver queues with repeated attempts due to impatience
(Simulation in Industry´2000, 2000) Artalejo Rodríguez, Jesús Manuel; López Herrero, María Jesús; Moller, DPF
We consider a multiserver queueing system where customers may become impatient and then retry for service after some random time. The study of this queueing model is motivated by the existence of exchange distributed operating systems with a time-out mechanism (Boyer et al. 1988). In this paper, we concentrate on the system performance under low retrial rate.
Numerical analysis of (s, S) inventory systems with repeated attempts
(Annals of Operations Research, 2006) Artalejo Rodríguez, Jesús Manuel; Krishnamoorthy, A.; López Herrero, María Jesús
This paper deals with a continuous review (s, S) inventory system where arriving demands finding the system out of stock, leave the service area and repeat their request after some random time. This assumption introduces a natural alternative to classical approaches based either on lost demand models or on backlogged models. The stochastic model formulation is based on a bidimensional Markov process which is numerically solved to investigate the essential operating characteristics of the system. An optimal design problem is also considered.
Cellular mobile networks with repeated calls operating in random environment
(Computers and Operations Research, 2010) Artalejo Rodríguez, Jesús Manuel; López Herrero, María Jesús
Many of the Currently used cellular networks have been constructed on the premise trial me retrial phenomenon is negligible and the operating environment is static. However. a proper modeling of the mobile cellular network cannot ignore the existence of repeated calls. Moreover, real systems often operate in varying environment conditions. In this paper, we show how the matrix-analytic formalism gives one the ability to construct and study versatile cellular mobile networks with user retrials operating in random environment. More concretely, we investigate two four-dimensional. Markovian models which allow us to represent two different options for the use of the guard channel concept. We put emphasis on the numerical evaluation of the redial behavior and the environmental factors on the system performance. This implies the performance analysis of a variety of descriptors including blocking probabilities (handover and fresh calls), mean average analysis, and waiting time in orbit.
The M/G/1 retrial queue: An information theoretic approach
(Statistics and Operations Research Transactions, 2005) Artalejo Rodríguez, Jesús Manuel; López Herrero, María Jesús; Conesa, David V.
In this paper, we give a survey of the use of information theoretic techniques for the estimation of the main performance characteristics of the M/G/1 retrial queue. We focus on the limiting distribution of the system state, the length of a busy period and the waiting time. Numerical examples are given to illustrate the accuracy of the maximum entropy estimations when they are compared versus the classical solutions.
Stochastic epidemic models with random environment: quasi-stationarity, extinction and final size
(Journal of Mathematical Biology, 2013) Artalejo Rodríguez, Jesús Manuel; Economou, A.; López Herrero, María Jesús
We investigate stochastic and epidemic models, when there is a random environment that influences the spread of the infectious disease. The inclusion of an external environment into the epidemic model is done by replacing the constant transmission rates with dynamic rates governed by an environmental Markov chain. We put emphasis on the algorithmic evaluation of the influence of the environmental factors on the performance behavior of the epidemic model.
The maximum number of infected individuals in SIS epidemic models: Computational techniques and quasi-stationary distributions
(Journal of Computational and Applied Mathematics, 2010) Artalejo Rodríguez, Jesús Manuel; Economou, A.; López Herrero, María Jesús
We study the maximumn umber of infected individuals observed during an epidemic for a Susceptible–Infected–Susceptible (SIS) model which corresponds to a birth–death process with an absorbing state. We develop computational schemes for the corresponding distributions in a transient regime and till absorption. Moreover, we study the distribution of the current number of infectedindividuals given that the maximum number during the epidemic has not exceeded a given threshold. In this sense, some quasi-stationary distributions of a related process are also discussed.