In this paper, we survey results for the GI/GI/N+ GI queueing model. Our focus is on finding
situations in which simple performance measure approximations can be developed. To do …

Service systems abound with queues, but the most natural direct models are often time-
varying queues, which may require nonstandard analysis methods beyond stochastic …

The performance of a call center is sensitive to customer abandonment. In this survey paper,
we focus on G/GI/n+ GI parallel-server queues that serve as a building block to model call …

We study a capacity sizing problem in a service system that is modeled as a single-class
queue with multiple servers and where customers may renege while waiting for service. A …

There are different workforce models in the “gig” economy. Although some on-demand
service providers rely strictly on either traditional employees or independent contractors …

This paper introduces a deterministic fluid model that approximates the many-server G
t/GI/st+ GI queueing model, and determines the time-dependent performance functions. The …

One prevalent assumption in queueing theory is that the number of servers in a queueing
model is deterministic. However, randomness in the number of available servers often arises …

In hospitals, Step Down Units (SDUs) provide an intermediate level of care between the
Intensive Care Units (ICUs) and the general medical‐surgical wards. Because SDUs are …

The service sector is an indisputable and fundamental pillar of today's business world,
encompassing nearly 80 percent of the workforce in the USA. Service operations …

We study the fluid model of a many-server queue with multiple customer classes and obtain
optimality results for this model. For the purpose of minimizing the long-run average queue …