Sustainable Cities Via Sustainable Supply Chains

Did you know that over one half of the world's population now resides in cities?

Which is your favorite city?

Might it be Boston?

or New York City?

perhaps Miami:

 

or Buenos Aires:

or Paris:

Stockholm:

Vienna:

or Shanghai?

I took all the above photos during speaking engagement trips over the past several years, except for the Shanghai one, which was taken by a former doctoral student of mine at the World Expo there.

When cities work well those who live in them can flourish in terms of mobility, health and welfare, accessibility, and innovation.


In the paper, "Design of Sustainable Supply Chains for Sustainable Cities," which is now accepted for publication in the journal, Environment & Planning B,  I emphasized  that cities, as dynamic complex networks, are the systems and the economic engines for commerce, research and development, education, healthcare, and even culture. They have evolved over space and time on built infrastructure from transportation networks to telecommunication and electric power networks.

At the same time, cities are the centers of resource usage from electricity and other forms of energy and fuel, to food, water, and a plethora of other products. Hence, they also are the repositories and generators of waste output and other environmental pollutants, such as carbon and other emissions, sewage, noise, etc. The term Sustainable Cities has come into increasing use in the past two decades, with a focus of making cities more livable, with an eye not only on the present generation but towards future ones, as well.

Our world is becoming a network of interconnected cities or a supernetwork of cities with  urbanization is one of the most pressing and complex challenges of the 21st century, with the citizenry characterized by a growing awareness of a threat to the sustainability of the earth’s natural environment, coupled with the increase in the number of people moving into and living in cities.

Cities are supplied by a complex array of supply chains servicing an immense spectrum of economic activities from food stores and restaurants, office supplies and high tech equipment, apparel, construction materials, as well as raw materials, to name just a few. The sustainability of supply chains is, hence, a precursor to the sustainability of our cities.

According to a Business for Social Responsibility (2009) paper, it is now widely acknowledged that making significant progress on mitigating the impact of climate change depends on reducing the negative environmental impacts of supply chains through their redesign and enhanced management (see also McKinsey Quarterly, 2008). Furthermore, as noted by Capgemini in its 2008 report: 2016: Future Supply Chain, “Preserving energy and raw materials and other resources like water will become a crucial aspect in future supply chains, as costs will likely remain volatile and supplies will continue to dwindle.”

These conditions may well create substantial pressure on current supply chain models.

In this paper, I constructed a new computable mathematical model,  that is network-based, for the design of sustainable supply chains with a focus on cities that captures the frequency of network link operations, which is especially relevant to cities due to frequent freight deliveries. An algorithm was then proposed, along with convergence results, and implemented for the computation of several numerical examples.

One of the goals in the paper was to demonstrate how, through the proper design (and operation) of these complex networks, waste can be reduced, along with the environmental impacts, while minimizing operational and frequency costs, and meeting demand.

For a presentation, with the same name, which also includes intellectual foundations inspired by Professor Martin Beckmann, the co-author of the classic book, Studies in the Economics of Transportation,  click here.

The Supply Chain Network Design for Critical Needs with Outsourcing Paper is Now Published Online

Our paper, "Supply Chain Network Design for Critical Needs with Outsourcing," has now been made available online by the publisher, John Wiley & Sons, in the journal Papers in Regional Science.

With the number of disasters growing over the past decade as well as the number of people affected by disasters, the design of supply chain networks for critical needs products, such as water, food, and medicines, is of paramount importance. Such problems are uniquely challenging since the needs of the affected population should be met as closely as possible with the undersupply of food, water, and medicines, leading to loss of life. At the same time, the oversupply of products may also carry costs, due to unnecessary waste and even, possibly, environmental damage.

In fact, the United Nations is reporting in today's New York Times that the horrific floods in Pakistan are resulting in severe shortages of such critical needs supplies as food and water.

In our paper, we developed a mathematical model that allows for the optimal design of such supply chain networks at minimal total cost and with the satisfaction of the product demands at the demand points, as closely as possible.

Research on which this paper was based, which was conducted also by Professor Patrick Qiang and my doctoral student, Min Yu, was inspired by the Humanitarian Logistics: Networks for Africa Conference that I organized at the Rockefeller Foundation's Bellagio Center on Lake Como. The Rockefeller Foundation and this workshop are acknowledged in the paper. We also thank Professor Manfred Fischer of the Vienna University of Business and Economics for his support. Professor Fischer was my host in Vienna in March 2009 when I delivered the lecture, "Synergies and Vulnerabilities of Supply Chain Networks in a Global Economy."

Fashion Supply Chain Management and Sustainability

Yesterday, one of my doctoral students and I finished a paper on fashion supply chain management that we were invited to write. Today, I see that The New York Times has an article on the fashion and apparel industry with a call for minimizing waste.

I enjoyed the article a lot since it highlighted the supply chain aspects of emission reduction, including the emissions generated in the transportation of fashion products, as well as the design of fashion products, such as jeans,which can be notoriously, and, ironically, I might add, environmentally-unfriendly due to the dyes used. What is particularly challenging about fashion and apparel design, as the article emphasizes, is that fashion should also look good. Hence, perhaps we now should also be concerned, as operations researchers and supply chain network designers, not only about the sustainability issues but also about the aesthetics, or shall we leave it to the Parsons School of Design folks who were quoted in the article. As for minimizing waste in this application sector, our discipline can contribute immensely since we have a long history and excellent track record in a variety of "cutting" problems, whether for paper products or fabric.

Our recent paper, "Sustainable Supply Chain Network Design: A Multicriteria Perspective," just published in the International Journal of Sustainable Engineering is definitely relevant to this topic as is the paper, "Fashion Supply Chain Management Through Cost and Time Minimization from a Network Perspective," which we have just completed.

If someone had told me a while back that I would be doing research on fashion supply chain management, I would have said that there are other problems of greater interest to me. I do recall, however, being at a terrific workshop at Stanford years back with both Professor Kenneth Arrow, the Nobel Laureate, in the audience, and Professor George Dantzig, the father of operations research, along with my former dissertation advisor at Brown University, Stella Dafermos. After my talk at the workshop, someone remarked that they thought I was talking about "Wardrobe" equilibrium, rather than "Wardrop" equilibrium (well-known to those who work and study transportation and logistics). I had a good laugh after this.

Clothes are rather basic and important, don't you think, and if one can assist this industry in sustainability, one can make a big impact.

Minimizing the Carbon Footprint Through the Design of Sustainable Supply Chains

It's official -- our paper, "Sustainable Supply Chain Network Design: A Multicriteria Perspective," has now been published in the International Journal of Sustainable Engineering. It appears in the September issue, volume 3 (2010), pp. 189-197 and can be accessed here.

The paper already has been receiving a lot of attention based on queries that I have gotten from publishers to expand the paper into a book.

With all the disasters in the world from floods to heat waves and fires, rigorous methodological tools that determine how to minimize the carbon footprint through sustainable supply chain network design can make a big difference in terms of emissions and costs.

Supply chains, as complex networks, consisting of manufacturing plants, different modes of transportation and distribution, as well as possible storage technologies, can span the globe and, hence, identifying the optimal design of such networks in terms of both costs and emissions, notably, in terms of the carbon generated, can impact not only a firm's profits but also its reputation through an enhanced environmental reputation.

We are delighted that our research and paper can contribute in this direction.

Supply Chain Network Design for Critical Needs at NetSci2010

I will be at MIT for the NetSci2010 Conference over the next couple of days and will be presenting the paper, "Supply Chain Network Design for Critical Needs with Outsourcing." The paper has been accepted for publication in the journal, Papers in Regional Science. The presentation may be downloaded here. I will be going with one of my doctoral students, Min Yu, who is a co-author with me of the paper, along with Dr. Qiang "Patrick" Qiang.

The conference should be very interesting and the venue of the Media Lab should be perfect. I am looking forward to seeing many colleagues there.

Will be Speaking on Supply Chain Network Design for Critical Needs at NetSci2010

The NetSci2010 Conference will be taking place next week at the Media Lab at MIT, which is a gorgeous venue. I will be delivering the paper: Supply Chain Network Design for Critical Needs with Outsourcing, which is joint work with Dr. Patrick Qiang and my doctoral student, Min Yu.

The abstract of the paper is below:

Abstract: In this paper we consider the design of supply chain networks in the case of critical needs as may occur, for example, in disasters, emergencies, pending epidemics, and attacks affecting national security. By "critical needs" we mean products that are essential to the survival of the population, which can include, for example, vaccines, medicine, food, water, etc., depending upon the particular application. "Critical" implies that the demand for the product should be met as nearly as possible since otherwise there may be additional loss of life.

The model that we develop captures a single organization, such as the government or a major health organization or corporation that seeks to "produce" the product at several possible manufacturing plants, have it stored, if need be, and distributed to the demand points. We assume that the organization is aware of the total costs associated with the various operational supply chain network activities, knows the existing capacities of the links, and is interested in identifying the additional capacity outlays, the production amounts, and shipment values so that the demand is satisfied with associated penalties if the demand is not met (as well as penalties with oversupply, which are expected to be lower). In addition, the organization has the option of outsourcing the production/storage/delivery of the critical product at a fixed/negotiated price and with the capacities of those entities being fixed and known. The solution of the model provides the optimal capacity enhancements and volumes of product flows so as to minimize the total cost, which we assume to be a generalized cost, and can include time, subject to the demands being satisfied, as nearly as possible, under demand uncertainty.