Whitt Ward

Ward Whitt

Information about the author Ward Whitt will soon be added to the site.
Found 104 papers in total
Many-server loss models with non-poisson time-varying arrivals
Many-server loss models with non-poisson time-varying arrivals
2017
This article proposes an approximation for the blocking probability in a...
Heavy-traffic fluid limits for periodic infinite-server queues
Heavy-traffic fluid limits for periodic infinite-server queues
2016
To better understand what stochastic model might be appropriate in applications with...
Approximations for heavily loaded G/GI/n + GI queues
Approximations for heavily loaded G/GI/n + GI queues
2016
Motivated by applications to service systems, we develop simple engineering...
Using a birth-and-death process to estimate the steady-state distribution of a periodic queue
Using a birth-and-death process to estimate the steady-state distribution of a periodic queue
2015
If the number of customers in a queueing system as a function of time has a proper...
Choosing arrival process models for service systems: Tests of a nonhomogeneous Poisson process
Choosing arrival process models for service systems: Tests of a nonhomogeneous Poisson process
2014
Service systems such as call centers and hospital emergency rooms typically have...
Continuous‐time Markov chain models to estimate the premium for extended hedge fund lockups
Continuous‐time Markov chain models to estimate the premium for extended hedge fund lockups
2013
A lockup period for investment in a hedge‐fund is a time period after making...
OM ForumOffered Load Analysis for Staffing
OM ForumOffered Load Analysis for Staffing
2013
This essay, based on my 2012 MSOM Fellow Lecture, discusses an idea that has been...
A Fluid Limit for an Overloaded X Model via a Stochastic Averaging Principle
A Fluid Limit for an Overloaded X Model via a Stochastic Averaging Principle
2013
We prove a many‐server heavy‐traffic fluid limit for an overloaded...
Two‐parameter heavy‐traffic limits for infinite‐server queues with dependent service times
Two‐parameter heavy‐traffic limits for infinite‐server queues with dependent service times
2013
This paper is a sequel to our 2010 paper in this journal in which we established...
Real-Time Delay Estimation Based on Delay History in Many-Server Service Systems with Time-Varying Arrivals
Real-Time Delay Estimation Based on Delay History in Many-Server Service Systems with Time-Varying Arrivals
2011
Motivated by interest in making delay announcements in service systems, we study...
Heavy‐traffic limits for nearly deterministic queues: stationary distributions
Heavy‐traffic limits for nearly deterministic queues: stationary distributions
2011
We establish heavy‐traffic limits for stationary waiting times and other...
Large‐time asymptotics for the G t /M t /s t +GI t many‐server fluid queue with abandonment
Large‐time asymptotics for the G t /M t /s t +GI t many‐server fluid queue with abandonment
2011
We previously introduced and analyzed the G t / M t / s t + GI t...
Two-parameter heavy-traffic limits for infinite-server queues
Two-parameter heavy-traffic limits for infinite-server queues
2010
In order to obtain Markov heavy-traffic approximations for infinite-server queues with...
Service-level differentiation in many-server service systems via queue-ratio routing
Service-level differentiation in many-server service systems via queue-ratio routing
2010
Motivated by telephone call centers, we study large-scale service systems with...
Heavy-traffic extreme value limits for Erlang delay models
Heavy-traffic extreme value limits for Erlang delay models
2009
We consider the maximum queue length and the maximum number of idle servers in the...
Queue-and-idleness-ratio controls in many-server service systems
Queue-and-idleness-ratio controls in many-server service systems
2009
Motivated by call centers, we study large-scale service systems with multiple customer...
Heavy-traffic limits for many-server queues with service interruptions
Heavy-traffic limits for many-server queues with service interruptions
2009
We establish many–server heavy–traffic limits for G/M/n+M...
Power algorithms for inverting Laplace transforms
Power algorithms for inverting Laplace transforms
2007
This paper investigates ways to create algorithms to invert Laplace transforms...
A unified framework for numerically inverting Laplace transforms
A unified framework for numerically inverting Laplace transforms
2006
We introduce and investigate a framework for constructing algorithms to invert Laplace...
The impact of increased employee retention on performance in a customer contact center
The impact of increased employee retention on performance in a customer contact center
2006
A mathematical model is developed to help analyze the benefit in contact-center...
Two-moment approximations for maxima
Two-moment approximations for maxima
2007
We introduce and investigate approximations for the probability distribution of the...
What you should know about queueing models to set staffing requirements in service systems
What you should know about queueing models to set staffing requirements in service systems
2007
One traditional application of queueing models is to help set staffing requirements in...
Value-based routing and preference-based routing in customer contact centers
Value-based routing and preference-based routing in customer contact centers
2007
Telephone call centers and their generalizations – customer contact centers...
Coping with time-varying demand when setting staffing requirements for a service system
Coping with time-varying demand when setting staffing requirements for a service system
2007
We review queueing-theory methods for setting staffing requirements in service systems...
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