# Searching for solutions to make queues more efficient

(30-08-2022) Arnaud Devos, in his PhD, is investigating how queues can be made more efficient.

Who hasn't been irritated by being put on hold too long when calling a supplier? In queueing theory, one studies and explains the phenomena that occur in queueing systems where customers wait to be served.

Queuing systems are analyzed mathematically using techniques from probability theory with the goal of finding the most effective measures against excessive waiting time. After all, queues often lead to a lot of irritation and, in the worst case, even to loss of customers.

"In my PhD, I study a queueing model where 2 types of customers wait for some form of service by the same server," Arnaud explains.

"The order in which the two types of customers are served can be done in different ways. For example, one could choose to give absolute priority to one type of customer. In the emergency department of a hospital, for example, one should distinguish between patients who need immediate help and those who need less urgent treatment," Arnaud explains.

"However, in some queuing systems, a fair distribution of limited resources is desirable. For example, in queues at your municipality's service center or at your post office where you have different types of customers but only 1 counter," Arnaud continues.

"Such queues where a single server alternately distributes its time randomly, I study in my research. In doing so, I limited myself to 2 types of customers and mainly focused on the solution method to analyze this queueing model"

"This thesis aims to better understand the queueing model. In particular, I pay much attention to the mathematical difficulty of 'solving' this model by providing different solution methods and considering special cases", concludes Arnaud.

Read a more detailed summary or the entire PhD

PhD Title: Analysis of a Two-Class Queueing Model with Randomly Alternating Service

### Arnaud Devos

Arnaud Devos was born in Oudenaarde, Belgium, on January 18, 1994. He obtained a degree in Economics-Mathematics in secondary education in 2012. He then enrolled at Ghent University for the Mathematics program, which he successfully completed in 2017. In that same year, he got the opportunity to perform research within the SMACS research group under the supervision of Prof. Herwig Bruneel, Prof. Joris Walraevens and Prof. Dieter Fiems.

His research focused on the analysis of two-dimensional queueing models. Arnaud has made several contributions to improve the analysis of such models. Arnaud is first author of four A1 publications. He has presented his work at three different international conferences. At one of these conferences, his work was awarded as best student paper. Finally, Arnaud was involved in several teaching assignments during his doctoral research.

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Editor: Jeroen Ongenae - Illustrator: Roger Van Hecke