• Publications
  • Influence
Designing a Call Center with Impatient Customers
TLDR
This paper analyzes the simplest abandonment model, in which customers' patience is exponentially distributed and the system's waiting capacity is unlimited ( M/ M/ N +M), and derives approximations for performance measures and proposes "rules of thumb" for the design of large call centers.
Dimensioning Large Call Centers
TLDR
A framework for asymptotic optimization of a queueing system based on the staffing problem of call centers with 100's of agents is developed, and the square-root safety staffing principle is revisited, which is a long-existing rule-of-thumb for staffing the M/M/N queue.
Echelon Reorder Points, Installation Reorder Points, and the Value of Centralized Demand Information
We consider a serial inventory system with N stages. The material flows from an outside supplier to stage N, then to stage N - 1, etc., and finally to stage 1 where random customer demand arises.
Reflected Brownian Motion on an Orthant
We consider a K-dimensional diffusion process Z whose state space is the nonnegative orthant. On the interior of the orthant, Z behaves like a Kdimensional Brownian motion with arbitrary covariance
Open Queueing Networks in Heavy Traffic
  • M. Reiman
  • Mathematics, Computer Science
    Math. Oper. Res.
  • 1 August 1984
TLDR
These limit theorems state that properly normalized sequences of queue length and sojourn time processes converge weakly to a certain diffusion as the network traffic intensity converges to unity.
Economics of Product Development by Users: the Impact of Sticky Local Information
TLDR
It is argued that agency-related costs and information transfer costs will tend drive the locus of problem-solving in the opposite direction-away from problem-Solving by specialist suppliers, and towards those who directly benefit from a solution and who have difficult-to-transfer local information about a particular application being solved, such as the direct users of a product or service.
Strong approximations for Markovian service networks
TLDR
This work develops limit theorems for a large class of stochastic service network models where parameters like arrival and service rates, routing topologies for the network, and the number of servers at a given node are all functions of time as well as the current state of the system.
The multiclass GI/PH/N queue in the Halfin-Whitt regime
We consider a multiserver queue in the heavy-traffic regime introduced and studied by Halfin and Whitt who investigated the case of a single customer class with exponentially distributed service
A boundary property of semimartingale reflecting Brownian motions
SummaryWe consider a class of reflecting Brownian motions on the non-negative orthant inRK. In the interior of the orthant, such a process behaves like Brownian motion with a constant covariance
Some diffusion approximations with state space collapse
TLDR
The study of diffusions, which are essentially continuous path Markov processes, reduces most questions of interest to the study of certain differential equations, and can obtain both insights into and approximations for systems with more general characteristics.
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