Sunday, February 28, 2021

An Update on Our Supply Chain Research with the Inclusion of Labor in the COVID-19 Pandemic

In less than two weeks,  on March 11, 2021, we will be marking the first "anniversary" of the World Health Organization declaring the COVID-19 pandemic. It has been a year like no other in our lifetimes.

It has also been a year in which many researchers and practitioners have tried to do their best in addressing many of the complex problems that have resulted, as a consequence of the pandemic. What has especially resonated with me has been the criticality of numerous supply chains from PPE and medical supply ones (and now even those associated with vaccines) to food. The shortcomings associated with such supply chains have included the fact that labor has been very seriously impacted in the pandemic with many falling ill, some succumbing to the disease, and others working in quite challenging circumstances with added stressors and anxiety, as well as new procedures, in terms of social distancing requirements, for example.

The importance of people in supply chains, including healthcare ones, has, hence, stood out. However, there was not much scientific literature that addresses disruptions on labor and impacts on supply chains. So, as a researcher and educator,  I decided to delve deeper into constructing mathematical models, both optimization and game theory ones, that would shed light on labor availability, losses in productivity, and related issues.

I am pleased to say that a series of my papers on this topic has now been accepted for publication, the first of which, was on food. The paper, "Perishable Food Supply Chain Networks with Labor in the Covid-19 Pandemic," is now in press in the refereed, edited volume: Dynamics of Disasters - Impact, Risk, Resilience, and Solutions,  I.S. Kotsireas, A. Nagurney, P.M. Pardalos, and A. Tsokas, Editors, Springer International Publishing Switzerland, 2021.

This paper explicitly captures the perishability of food from points of production to points of demand. The firm is considered to be a profit-maximizer and also encumbers costs associated with paying for labor. Each link in the supply chain network has a bound on the labor availability and also a productivity factor associated with labor. The demands for the food items are assumed to be elastic.

In the second paper in the series, "Optimization of Supply Chain Networks with Inclusion of Labor: Applications to COVID-19 Pandemic, now in press in The International Journal of Production Economics, I turn to expanding the ideas in the first paper, with a focus on healthcare products, and with consideration of 3 different sets of constraints on labor, under, first elastic demand, and then, under fixed demands. The latter is important since in the case of certain products, especially healthcare ones, demand may be inelastic when it comes to price.

And, in the third paper in this series, "Supply Chain Game Theory Network Modeling Under Labor Constraints: Applications to the Covid-19 Pandemic," I utilize game theory to consider three different sets of constraints in a supply chain network model consisting of multiple competing firms. The paper is now available online in the European Journal of Operational Research. Therein, I also capture three sets of constraints for labor but, now, in the case of two of the sets, the firms compete for labor. In this work, the first model is a Nash Equilibrium one, whereas the other two are Generalized Nash Equilibrium models.

The above work integrates economics and operations research and the underlying methodological formalism is that of the theory of variational inequalities.

This series of papers further inspired me to write an article for The Conversation, entitled: "Vaccine delays reveal unexpected weak link in supply chains: A shortage of workers."

I was honored to be, subsequently, invited to write a follow-up article, "In the End, It's All About People," by Kara Tucker, the new Editor of the INFORMS publication, ORMS Today

And, if you would like to learn more, please, feel free to listen to the INFORMS podcast: "Shining a light on the COVID-19 vaccine distribution," in which I am interviewed by Ashley Kilgore.

The three papers of mine, highlighted above, are all dedicated to essential workers! We are so grateful for their contributions in the past; in the pandemic, and wish them the very best in the future!