Sustainability and Operations Research: A Trek Down Memory Lane from Transportation to Supply Chains

Given the interest my blogpost on Professor Joe Sarkis' talk on greening supply chains generated I thought that I would write this piece on sustainability and operations research from the perspective of how we got interested in the subject and where it has taken us.

Professor Sarkis also mentioned in his presentation that he, like I and my research group, have been working on sustainability for a while - actually two decades and since we are hearing that "sustainability" is some fields, including operations management, is being perceived as being relatively new, I thought it deserved some commentary.

I have always been one who loves nature and I get some of my best ideas on hikes. Clean air, clean water, fresh food, and a healthy, peaceful environment we all deserve and they are essential to our well-being  and that of future generations.

As a research topic, I became interested in sustainability while working with two doctoral students at the Isenberg School of Management: Kanwalroop "Kathy" Dhanda and Padma Ramanujam in the 1990s.

Together we wrote the Environmental Networks book, which was published in 1999, and the year after, my Sustainable Transportation Networks book was published.

Vice President Al Gore wrote me a nice letter on the publication of my Sustainable Transportation Networks book, which now hangs in my office at the Isenberg School.

Prior to the publication of these books, I had co-authored several papers, which also provided the seeds for our sustainability work. These included a 1996 paper in Operations Research, written with Sten Thore and one of my first PhD students, Jie Pan, who tragically died of an autoimmune disease shortly after having receiving tenure. With Padma, that same year, we had also published a paper in Transportation Science.

Padma's dissertation,  Transportation Network Policy Modeling for Congestion and Pollution Control: A Variational Inequality Approach, was awarded a Transportation Science & Logistics dissertation prize from INFORMS in 1999, a great honor.

Some other early papers on various sustainability of ours included: "A Multimodal Traffic Network Equilibrium Model with Emission Pollution Permits: Compliance versus Noncompliance," published in Transportation Research D in 1998 and "Marketable Pollution Permits in Oligopolistic Markets with Transaction Costs," which appeared in Operations Research in 2000. I also wrote several papers on emission paradoxes, one with another doctoral student of mine, now Professor June Dong.

Hence, we were proposing tradeable pollution permits even for transportation networks in the 1990s. Padma is now working at SAS, a fabulous analytics firm, and is based in Cary, North Carolina, whereas Kathy has had several tenured professorships at different universities and continues to work on sustainability issues.

Interestingly, the Virtual Center for Supernetworks, which I founded in 2001 and continue to serve as Director of, was initiated because of three NSF grants that I had received at that time plus two AT&T Industrial Ecology Fellowship grants, which envisioned such a center. Hence, the sustainability theme has been central to our research.

In 2005, with a doctoral student from Japan, Fuminori Toyasaki, who is now a professor at York University in Toronto, I published a paper that is highly cited: "Reverse Supply Chain Management and Electronic Waste Recycling: A Multitiered Network Equilibrium Framework for E-cycling." This paper was recognized by Transportation Research E as a most cited paper.

In 2002, I had co-authored the paper, "A Supply Chain Network Equilibrium Model," with June Dong and Ding Zhang and this paper, which introduced multiple tiers of interacting decision-makers, who compete across a tier but cooperate between tiers, generated new frameworks for work on sustainability and supply chains as well. We also conducted research on energy supply chains and I have a series of papers in this area, some of which also include carbon taxes. An example is the paper, "Modeling Generator Power Plant Portfolios and Pollution Taxes in Electric Power Supply Chain Networks: A Transportation Network Equilibrium Transformation," co-authored with Kai Wu, Zugang Liu (another former PhD student of mine who is now a tenured professor), and John Stranlund, a faculty member at UMass in Resource Economics.

Another former very successful doctoral student of mine, Trisha Anderson Woolley, now a tenured professor,  also published several papers with me on sustainability, energy, and supply chains, as well as policy interventions. 

As the news about climate change resonated and its negative impacts, we continued to explore modeling of supply chains and an example of a paper reflecting this is: "Environmental Impact Assessment of Transportation Networks with Degradable Links in an Era of Climate Change, " which was published in 2010 and written with Patrick Qiang, my co-author of the Fragile Networks book (and whose dissertation received the Charles Wootan Award from the CUTC), and the "other" Professor Nagurney - Ladimer S. The paper, "Sustainable Supply Chain Network Design: A Multicriteria Perspective," written by the two Nagurneys, which was also published in 2010, remains one of the most highly cited articles in the International Journal of Sustainable Engineering.

Our more recent research on sustainability and supply chains has focused on numerous different applications, and these are quite fascinating. Much of the impetus has come from outside - such as our work on fashion and sustainability - but some of it has also been internal - as in the case of our blood supply chain sustainability research and driven by common interests and passion that I share with both students and collaborators. Examples of such papers are: Sustainable Fashion Supply Chain Management Under Oligopolistic Competition and Brand Differentiation, Anna Nagurney and Min Yu, International Journal of Production Economics, Special Section on Green Manufacturing and Distribution in the Fashion and Apparel Industries 135: (2012) pp 532-540 and Supply Chain Network Design of a Sustainable Blood Banking System, Anna Nagurney and Amir H. Masoumi, in Sustainable Supply Chains: Models, Methods and Public Policy Implications, T. Boone, V. Jayaraman, and R. Ganeshan, Editors, Springer, London, England (2012) pp 49-72.

In 2014, I was delighted to co-author a paper with two of my former PhD students, Toyasaki, already mentioned, and Professor Tina Wakolbinger, and her first PhD student, Thomas Nowak, who has since received his PhD: When and for Whom Would E-waste be a Treasure Trove? Insights from a Network Equilibrium Model of E-waste Flows, Tina Wakolbinger, Fuminori Toyasaki, Thomas Nowak, and Anna Nagurney, International Journal of Production Economics 154: (2014) pp 263–273.


Some of our other recent research has included my collaborator in Sweden, Professor Jonas Floden, since I had a fabulous Visiting Professorship at the University of Gothenburg over a 4 year period. Examples are the papers: Supply Chain Network Sustainability Under Competition and Frequencies of Activities from Production to Distribution, Anna Nagurney, Min Yu, and Jonas Floden, Computational Management Science 10(4): (2013) pp 397-422 and Fashion Supply Chain Network Competition with Ecolabelling, Anna Nagurney, Min Yu, and Jonas Floden, in Sustainable Fashion Supply Chain Management: From Sourcing to Retailing, T.-M. Choi and T.C.E. Cheng, Editors, Springer (2015) pp 61-84.

Another paper that I am quite proud of in which I move from transportation to supply chains to sustainable cities is, "Design of Sustainable Supply Chains for Sustainable Cities," invited paper for the Complex-City Workshop, December 5-6, 2011, Amsterdam, The Netherlands, Environment & Planning B 42(1): (2015) pp 40-57.

Our research on food supply chains, conducted with Professor Min Yu (yes, another former terrific Isenberg UMass PhD alumna in Management Science), and published in the European Journal of Operational Research, also has components of sustainability since we consider waste. The same holds for our work on pharmaceutical supply chains.

And, for those of you interested in perishable product supply chains, including food and medical nuclear ones, in which waste is a big issue, our Networks Against Time: Supply Chain Analytics for Perishable Products, is recommended.

And the research continues into its third decade!

Greening the Supply Chain: Insights From One of the World's Leading Scientific Minds - Professor Joe Sarkis

Today we were honored and delighted to have Professor Joe Sarkis, the head of the Department of Management within Worcester Polytechnic Institute's (WPI) Foisie School of Business, deliver the lecture, "Supplier Collaboration and Development for Greening Supply Chains," as part of our UMass Amherst INFORMS Speaker Series. The series is organized by the UMass Amherst INFORMS Student Chapter so a special thanks to the chapter President, Pritha Dutta, a doctoral student in Management Science at the Isenberg School of Management, for handling the logistics and for designing the nice poster below.

The talk was even announced on the UMass Amherst homepage today.

And, interestingly, and coincidentally, if you look closely at the above homepage snapshot you will also see on the left under "News" the article on Seven UMass Amherst Researchers Named among 'World's Leading Scientific Minds.' In this 2016 Thomson Reuters survey of highly cited scientists is also our speaker today, Professor Joe Sarkis, and he is listed in the Engineering category so do check it out. He is renowned for his work on sustainability and supply chains and today he attracted an audience from the Isenberg School of Management, the College of Engineering, the Department of Environmental Conservation, among others. Just look at his Google Scholar citations.

He motivated his presentation by noting a 2016 McKinsey report on Supply Chain Management and emphasizing the importance of greening the supply chain to industry with the "leading edge of thought" should also be the "leading edge of practice." "We should be doing good," he said, and emphasized the gold mine of research in this area and that showed throughout his presentation as did his passion and energy. He has collaborated with researchers from China, from Egypt, and other countries and, I do admit I am now also working on a paper with him and with two of my former doctoral students, Dr. Sara Saberi who just started as an Assistant Professor at the Foisie Schoo of Business, and Dr. Jose Cruz, from the School of Business at the University of Connecticut, whose work was also mentioned in Sarkis' presentation.

He emphasized levels of problems and different methodologies and theories to tackle them - from global problems, such as global warming, to regional problems of deforestation and acid rain, to more local problems of pesticides and waste.

Of course, he had to mention that there are many different definitions of environmental sustainability (and he even authored a paper on this) and recognized the importance of ISO 14000, life cycle analysis (LCA), and carbon and water footprints. When it comes to supply chains it is essential to "close the loop" and deal not only with forward and reverse supply chains separately. He remarked that energy research is also important for supply chain management and stated that teaching informs his research and vice versa. I so agree with the latter statement and continue to be inspired by questions that my students raise.

It was wonderful to have my Isenberg School colleague, Professor Marta Calas, in the audience since she is working with a doctoral student on sustainability and the fashion brand Eileen Fisher. We have published several papers on fashion and sustainability with my former doctoral student, and now Assistant Professor at the University of Portland, Dr. Min Yu.

The relevance of theory, methodologies, and applications were emphasized and he also discussed whether carrots or sticks should be using for green supply chain management.

I very much liked what he said about different boundaries, including temporal ones, and associated decision-making. He also discussed the different types of flows that are relevant and since we work on networks, optimization, game theory, as well as sustainability I liked the flows of material, service, information, and financial ones noted very much. Also, I appreciated him mentioning different industries from food to the textile industry. On the latter, he is working with a collaborator in Egypt. Afterwards, a doctoral student and UMass Amherst INFORMS Student Chapter officer, Ekin Koker,  brought up the automotive industry and sustainability.

Professor Sarkis spoke on his work on "supplier development" and the sharing of knowledge to help suppliers become greener and also about investment in greener technologies.

The theme of different "levels" also resonated, from the individual, to the organizational, the enterprise level, all the way to the circular economy. Also, how leadership in greening the supply chain affects motivation and employees.

When I asked him which paper he was most proud of, he mentioned his paper in Science, with co-authors from China and Italy, "Measuring China's Circular Economy." He also noted his paper with Zhu in the Journal of Operations Management, since it contains theory, methodology, and application and such papers tend to be highly cited. The history behind his Science paper was also fascinating, but you should ask him this.

The audience clearly had a great experience and benefited a lot from the presentation.

After the energizing and very inspiring talk, I took Professor Sarkis, two of his doctoral students from WPI that had joined us, and three doctoral students from UMass Amherst, Pritha Dutta, Deniz Besik, and Rodrgo Mercado,  to lunch at the University Club and the wonderful conversations continued. As Professor Sarkis said at lunch, there is no better life than being a Full Professor at a university!

The food was great and the conversation even better - amazing how some universities are incentivizing researchers to publish in good journals especially those outside the United States. Of course, we also exchanged notes on recent academic hires, the job market, etc. Interestingly, both the Dean of the Foisie School of Business and the Dean of the Isenberg School, Dr. Mark A. Fuller  (I admit I served on the search committee for the latter), are in the Information Systems field.

Many thanks to Professor Joe Sarkis for coming to the University of Massachusetts Amherst today. You are welcome back any time! Thanks to Pritha Dutta for capturing the "Bon Voyage"in the photo below.

The Greening of the Metropolis

On my flights back from the ALIO-INFORMS in Buenos Aires, Argentina I had the distinct pleasure of reading the latest issue of Bloomberg Businessweek. There was a special segment in it on Clean Energy and an excellent article, "The Greening of the Metropolis." With cities being home to more than half of the world's population and generating more than two thirds of the world's carbon dioxide, greening of our megacities can make a significant difference in improving the environment.

I am hopeful. With the leadership of some of the biggest cities in the world taking proactive, creative steps to reduce emissions, much can be accomplished especially since regions and nations are failing to act.

Kudos to Los Angeles and its mayor, Antonio Villaraigosa, for 1,700 miles of bike paths that are to be completed by 2015, complete with showers and bicycle storage areas.

Bravo to the mayor of Toronto, David Miller, who plans on investing over $1 billion in public transport and environmentally-friendly air-conditioning systems for buildings.

In Tokyo, where, amazingly, 68 percent of the trips are by bike, subway, or on foot, in April a cap and trade system was instituted for carbon dioxide that is city-wide. As for Houston, Texas, where an astonishing 95% of the trips are made by car, at least officials are getting electric cars to reduce emissions.

Robert Doyle, the Lord Mayor of one of my favorite cities, Melbourne, in Australia, plans to bar cars from downtown and to offer incentives for green investments.

Copenhagen, in Denmark, is spending over a billion and a half dollars on bike paths, green energy projects, and retrofitting city buildings.

Amsterdam's infrastructure is being improved to the tune of 1 billion dollars, with its 2,400 houseboats being retrofitted to use electricity instead of diesel.

New York City, one of my absolutely favorite cities, since I grew up in Yonkers, is moving forward with its PlaNYC, to make buildings more energy efficient, power plants more environmentally-friendly, and with tax breaks for the use of solar panels.

Having spent over a week recently in another megacity -- Buenos Aires, Argentina, with about 11 million people in the central and surrounding areas, I know that much needs to be done.

The architecture of this city is stunning as are the neighborhoods with unique identities, and the lively, warm people and culture.

However, the traffic is horrendous with the busses running frequently but on diesel and their evident fumes spewing and belching out. Not only do they emit toxic pollutants but the noise that they generate is substantial. As one former Argentine physics colleague of my husband's, dating back to our Brown University days, told us during a lovely 3 hour dinner in Buenos Aires: when the busses go on strike, the people notice how much cleaner the air gets and how much more peaceful the city is even with more cars! Ironically, in parts of the developing world, getting rid of public transit with aging engines may actually improve air quality.

A better approach (and our colleague told us that he expects that this may happen but it will take about 10 years), is for the city of Buenos Aires (where 1/3 of Argentina's population lives) to purchase busses with the latest green technologies and with quieter designs.

Above are photos taken from the 14th floor of the Etoile Hotel in Buenos Aires where we spent last week. In the photos one can see the famous La Recoleta Cemetery where Eva Peron is buried and the Law School with the big columns, where the operations research conference that I attended and spoke at took place.

My talk at the ALIO-INFORMS conference was on "Sustainable Supply Chain Network Design: A Multicriteria Perspective" and it certainly hit "close to home." The paper is available here and the pdf of the presentation is here.