Sir Alan Wilson, Regional Science, Operations Research, and the Future of Cities

I returned last night from Europe where I spent the last 3 weeks at 3 different conferences and transiting between them. During this period I was privy not only to major current events but also history in the making since I was in Greece during the financial crisis (and ultimate bailout)  and even in Vienna where US Secretary of State John Kerry helped in the successful Iran nuclear negotiations.

This past week, I had the pleasure of taking part in the EURO 2015 conference in Glasgow, Scotland, which I have blogged about, and, on Tuesday, I was privileged to hear Professor Alan Wilson  of the University College London deliver his keynote talk on the Future of Cities in the beautiful Barony Hall, which was packed. He is the Professor of Urban Regional Systems. His extensive, wide-ranging contributions are both in research as well as in administration.

Sir Wilson began his talk by stating that "he secretly thought that he always was an Operations Researcher," and then stated that he is an Operations Researcher.

Coincidentally,  I know of his work through Regional Science and both Sir Alan Wilson and I were elected Fellows of the RSAI (Regional Science Association International) in the same year - in 2007!

Sir Wilson's passion is cities, since he is concerned with the biggest of big problems.

I so much enjoyed his plenary talk in which in emphasized nonlinearities, complex systems, and the high level of interdependencies in cities (just think of population and infrastructure, for example). He also emphasized the importance of transportation and networks and how infrastructur ties issues of population with the economics of cities.

He stated that his view as a math modeler is "to explore different futures for cities."

In his plenary, he also mentioned the role of engineers in transportation planning in the US so I have to note again the recent book by Professors David Boyce (who is both an INFORMS Fellow and an RSAI Fellow) and Huw Williams, Forecasting Urban Travel, which I have written about on this blog.  You can view Professor Boyce's presentation on 60 years of travel demand forecasting in which he notes the work of Alan Wilson here. 

Those of you who were listening closely to Sir Alan Wilson's plenary lecture, may have heard him mention Professor Suzanne Evans. Back in 2003, at a Regional Science conference, Suzanne Evans, joined me, Professor David Boyce, and Hani S. Mahmassani (well-known in transportation science and OR ) on a panel to commemorate the 50th anniversary of the publication of the network classic, Studies in the Economics of Transportation, by Beckmann (who was on my dissertation committee at Brown University), McGuire, and Winsten. You can see photos and presentation if you scroll down on this page.

Sir Wilson, in his ketnte, emphasized 6 challenges of cities in the United Kingdom, and stated that the challenges also apply to other cities and I agree. Specifically, he noted the challenges as being: people (demography), city economcs, the environment and sustainability, urban form (land use and green belts, which I am so passionate about), infrastructure, and governance.  He noted that the UK is very centralized and cities are pushing for more decentralization and autonomy.

As a math modeller, Wilson emphasized the high dimensionality of the problems associated with cities and discussed various scenarios for the future of London with powerful graphical displays. One scenario was what would happen if  "we killed off the car." Since I have done a lot of work on projected dynamical systems, I enjoyed hearing him speak about Lotka-Volterra dynamics (and relationships even to retail and hospitals), path dependence on initial conditions, forecasting challenges, and the importance of capturing uncertainty in dynamics.

And, since I had been in London, just a few days before travelinng to Edinburgh and then Glasgow, I have to include in this post one of my favorite green spaces in a city - Hyde Park in London.

Many thanks to the organizers of the great EURO conference in Glasgow for bringing to us such outstanding plenary speakers and many other presenters. It was an honor and delight to take part in it!

Bank Stability and Regulation Conference in Sweden and Small Academic World

Today and tomorrow I am taking part in a Finance conference here at the School of Business, Economics and Law at the University of Gothenburg in Sweden on Bank Stability and Regulation.

One of my finance colleagues here in Gothenburg, Professor Ted Lindblom, invited me and I have been enjoying the talks and meeting people very much. Below he is standing with another Finance colleague of mine here in Gothenburg, Professor Stefan Sjogren.

The academic world is so small - even though Finance is not my primary discipline (but I have co-authored the Financial Networks book and quite a few papers on multitiered financial networks and even the integration of financial and social networks),  I still find it very easy to talk to people and there is only "one ddegree of separation."

For example, Professor Deborah Lucas of MIT, with me below, knows my Isenberg School colleague, Professor Mila Sherman, very well, And Professor Manju Puri of Duke, who is also here, went to grad school at NYU with my colleague at Isenberg, Professor Nikunj Kapadia.

Plus, the first speaker today, Dr. Jiao Santos of the Federal Reserve Bank of New York, who gave a fabulous talk, has as his co-author on the paper, Matthew Plosser, whose father, Charles Plosser, is the President of the Federal Reserve Bank of Philadelphia. He is stepping down and Pat Harker, the President of the University of Delaware, an INFORMS Fellow, and former Editor of the journal, Operations Research, and whom I know, is becoming the next President and CEO of this institution.

Below I have posted some photos of the speakers and discussants and some of the papers have been made available and are accessible from the conference website:
 
Papers available:
Joao A.C. Santos, Federal Reserve Bank of New York and Nova School of Business and Economics; "Banks' Incentives and the Quality of Internal Risk Models"
Giorgia Piacentino, Washington University in St Louis; "Bank Capital, Bank Credit, and Unemployment"
Piero Gottardi, European University Institute and University of Venice; "Capital Structure, Investment, and Fire Sales"
Nittai K. Bergman, MIT; "Financial Accelerator at Work: Evidence from Corn Fields"
Paolo Fulghieri, University of North Carolina; "Uncertainty Aversion and Systemic Risk"

 I have enjoyed the diversity of topics and approaches, from empirical studies to theoretical general equilibrium models.  The presentations and discussions have been excellent and it would be interesting to apply such ideas as aggregate risk and aversion to uncertainty that I heard about today to supply chain networks.

The full program for the conference can be accessed here.

And, although I see many New York Yankees caps on  residents of Gothenburg, Professor Nittal Bergman of MIT brought his Red Sox cap, so I had to photograph it below. Nice to see folks from Massachusetts here in Sweden!

 Many thanks to the organizers of this great conference.

Disaster Relief - It's About Time

I have been busy co-organizing the 2nd International Conference on Dynamics of Disasters with my great colleagues, Professor Panos M. Pardalos of the University of Florida and Professor Ilias Kotsireas of Wilfrid Laurier University.

I've also been hard at work finishing up our paper for this conference, which takes place in Kalamata, Greece, at the end of June, and  grading the fascinating project papers of the students in my Humanitarian Logistics and Healthcare class.

Nice when your research is synergistic with your teaching!

The conference website now contains the program (to-date)  with confirmed speakers from many countries.

I have been completely engrossed in writing this paper, given the events in Nepal, post the 7.8 magnitude earthquake that struck in April.   One wants to help in any way possible and we have given a financial donation and, as as academics, we can certainly help through our research.

The title of the paper that I will be presenting at the conference is: "A Mean-Variance Disaster Relief Supply Chain Network Model for Risk Reduction with Stochastic Link Costs, Time Targets, and Demand Uncertainty."

This paper builds upon our earlier work in supply chain risk reduction (but in a corporate setting): Risk Reduction and Cost Synergy in Mergers and Acquisitions via Supply Chain Network Integration, Zugang Liu and Anna Nagurney, Journal of Financial Decision Making 7(2): (2011) pp 1-18, and our paper,  An Integrated Disaster Relief Supply Chain Network Model with Time Targets and Demand Uncertainty, Anna Nagurney, Amir H. Masoumi, and Min Yu, in Regional Science Matters: Studies Dedicated to Walter Isard, P. Nijkamp, A. Rose, and K. Kourtit, Editors, Springer International Publishing Switzerland (2015), pp 287-318.

Disaster relief is truly about time and models must incorporate the critical time dimension as ours do. For example, the U.S. Federal Emergency Management Agency (FEMA) has identified key benchmarks to response and recovery, which emphasize time and  they are: to meet the survivors’ initial demands within 72 hours, to restore basic community functionality within 60 days, and to return to as normal of a situation within 5 years. Timely and efficient delivery of relief supplies to the affected population not only decreases the fatality rate but may also prevent chaos.


There can be delays on any of the links in a disaster relief supply chain network and The New York Times on Monday, in an article  by Gardiner Harris, "Nepal's Bureaucracy Blamed as Quake Relief Supplies Pile Up," notes that:  Relief supplies for earthquake victims have been piling up at the airport and in warehouses here because of bureaucratic interference by Nepalese authorities who insist that standard customs inspections and other procedures be followed, even in an emergency, officials with Western governments and aid organizations said on Sunday. 


The article  continues with: The bottleneck was the fact that the bureaucratic procedures were just so heavy,” Jamie McGoldrick, the United Nations resident coordinator, said in an interview. “So many layers of government and so many departments involved, so many different line ministries involved. We don’t need goods sitting in Kathmandu warehouses. We don’t need goods sitting at the airport. We need them up in the affected areas.

We do  the following in our paper:  We develop a mean-variance disaster relief supply chain network model with stochastic link costs and time targets for delivery of the relief supplies at the demand points, under demand uncertainty. The humanitarian organization seeks to minimize its expected total operational costs and the total risk in operations with an individual weight assigned to its valuation of the risk, as well as the minimization of expected costs of shortages and surpluses and tardiness penalties associated with the target time goals at the demand points.


The risk is captured through the variance of the total operational costs, which is relevant to the reporting of the proper use of funds to stakeholders, including donors. The time goal targets associated with the demand points enable prioritization as to the timely delivery of relief supplies. The framework handles both the pre-positioning of relief supplies, whether local or nonlocal, as well as the procurement (local or nonlocal), transport, and distribution of supplies post-disaster. The time element is captured through link time completion functions as the relief supplies progress along paths in the supply chain network. Each path consists of a series of directed links, from the origin node, which represents the humanitarian organization, to the destination nodes, which are the demand points for the relief supplies.

We propose an algorithm, which yields closed form expressions for the variables at each iteration, and demonstrate the efficacy of the framework through a series of illustrative numerical examples, in which trade-offs between local versus nonlocal procurement, post- and pre-disaster, are investigated. The numerical examples include a case study on hurricanes hitting Mexico.

UMass Amherst has a nice release on this conference  and the University of Florida had this writeup posted a while back. 

I look forward to presenting our paper at the International Conference on Dynamics of Disasters. The topic is certainly so relevant and even NSF just released a big press release on 6 projects that it has funded, jointly with Japan, on Big Data and disaster response.

Big Bang Theory in Berlin

I am attending a huge physics conference - about 6,000 participants in Berlin, Germany and am here since I was invited by Professor Scholl who organized this conference.

Professor Scholl heard me speak at a workshop on Energy and Complex Networks last summer in Erice, Sicily and extended the kind invitation.

I have enjoyed the talks very much since there are quite a few talks on network problems.

Today was the first full day of presentations and it began with an excellent presentation by Dr. Dirk Helbing from ETH Zurich. He spoke on A Planetary Nervous System to Understand and Measure Our Society. I had last seen Dirk two Septembers ago at a terrific Risk Management Workshop in Zurich, Switzerland, at which we both spoke.

Dirk recorded his presentation this morning and said that it should be posted on Youtube in about 2 weeks.

At the end of the day I immensely enjoyed Dr. Duncan Watts' presentation: Computational Social Science: Exciting Progress and Future Challenges.

The talks here are very interdsciplinary, which I like very much. For example, Watts of small world fame, is a sociologist, who received his PhD from Cornell, and was at Columbia but is now with Microsoft in NYC.

His talk had two parts: the first focused on Twitter and the kind of analyses that he has been doing of rare events - messages that go viral. It was fascinating to learn that about 93% of Twitter posts never get retweeted even once. Those who get retweeted 100 times or more are a small fraction of tweets. He analyzed the network structure of such tweets, which are rare events, and require a huge sample for statistical purposes. He found that some viral tweets have a broadcast structure with the media playing a very important role. He said that if you want your message to spread write an OpEd and get it published in The New York Times. Of course, he noted that Justin Bieber and Katy Perry have 15 million followers so, in effect, that act as broadcasters, very often of images and videos (some of themselves).

In the second part of his presentation he spoke on Crisis Mapping, a project that he has worked on with the United Nations and also using Mechanical Turk.  This really interested me since I am teaching a course on Humanitarian Logistics and Healthcare. He was conducting research to map tweets during a disaster for the United Nations to get information about the disaster. He compared the information gleaned during a disaster versus using the same data but having individuals working in groups using Mechanical Turk. He found some unexpected results in that the larger the group the answers were not necessarily better.

Many of the researchers at this conference are interested in socio-economic phenomena and associated problems. I appreciate the methodologies that are being used and the scope of issues that physicists and the like are tackling.

Tomorrow morning I have the pleasure of introducing Dr. Luis Bettencourt of the Santa Fe Institute when he gives his invited talk on cities.

I will be speaking Wednesday morning.

It has been wonderful spending my spring break at this great conference in stately Berlin!

Complex-City Workshop in Amsterdam, The Netherlands

Next week I will be taking part in the COMPLEX-CITY Workshop, in Amsterdam, The Netherlands.

Each invited speaker/participant will be presenting an original research paper. I have completed my paper,"Design of Sustainable Supply Chains for Sustainable Cities," and am very much looking forward to presenting it and taking part in this workshop in one of my favorite cities.

This workshop is being organized by Dr. Peter Nijkamp and Dr. Emmanouil Tranos and will take place at the Tinbergen Institute/VU University. According to the organizers, the aim of the workshop is to bring together scholars with an expertise at the interface of spatial-urban dynamics and complexity theory. Through a presentation of advanced research papers, the organizers hope to ensure both a stock-taking of the scientific state of affairs in this field and an exploration of new and promising research endeavours. This workshop will be sponsored by the Royal Netherlands Academy of Arts and Sciences, and further supported by the Tinbergen Institute and the Department of Spatial Economics at the VU University, Amsterdam.

A more detailed Aims and Scope forwarded by the organizers can be found below.

Aims and Scope of the COMPLEX-CITY Workshop

With half of the world’s population now living in cities and predictions that this will rise to three quarters by the end of the 21^st century, cities represent one of the key foci around which important problems in real-world complex systems are clustered. There are clear policy implications for all dynamic urban models being developed. It seems logical that urban policy making should seek to intervene in much more sophisticated ways than hitherto and that complexity theory will provide us with the means for identifying how small changes can lead to dramatic and lasting beneficial effects which are both more equitable and efficient that anything developed hitherto. Pressing problems such as aging and climate change all involve changes in human behavior, particularly travel and social interactions, and our focus here directly identifies both data and models that are pertinent to these complexity issues.

Complexity prompts many intellectual challenges, both conceptually and empirically. The intellectual domain in which the workshop on COMPLEX-CITY is situated, is focused on the development and use of theories and models that explain, simulate and predict the dynamics of cities defined across spatial/geographical scales from the global to the local, from the world city to the village. In the last twenty years, the field has embraced new developments in complexity theory based on the inescapable logic that such systems mainly develop organically, from the bottom up, illustrating fascinating, surprising and sometime chaotic patterns of emergence, which show order al all scales and are hard to understand as anything but the remorseless action of decision-making at the lowest levels. This presents also one of the grandest of challenges to urban policy analysis: current policy instruments are often pitched at the wrong scale, producing methods of intervention which are largely ineffective in that they ignore the essential logic of the way such human systems actually develop.

The workshop has a stock-taking and exploratory nature and aims to identify critical parameters for urban policy analysis with respect to problems of development in large city systems. It will address new developments in complexity theory, based on the existing body of knowledge. What makes this particularly opportune is the fact that massive new streams of data with respect to movement and location patterns in city systems are rapidly becoming available. These are providing the momentum for new developments in theory and modeling which are taking the slow but sure developments of the last twenty years to new kinds of applications relevant to policy making. What is different is that comprehensive data are being routinely collected at the individual level relating to where economic and social activities are carried out in cities and how individuals cooperate and conflict with one another in geographical terms. The prospect exists for the first time of demonstrating how aggregate patterns in cities do actually emerge from bottom-up actions and interactions, linking physical patterns of transportation to social networks, patterns of trade to the flow of information. These developments rely on unobtrusive and automatic data collection using digital technologies that are penetrating every aspect of social and economic life, providing unprecedented possibilities for the analysis of data about human spatial behaviour. This is essential in taking complexity science to the point where it becomes truly applicable in urban policy analysis.

The quest of the workshop is to demonstrate how several long-standing ideas about urban dynamics can be tested and validated using new data sources that provide information about routine decision-making concerning locations and interactions. We envisage that many well-established models of the mechanisms governing how cities change are built around models of reaction-diffusion, which generate both smooth and abrupt change reminiscent of criticality, catastrophe, and chaos, can be tested and extended using new digital data. These range from a synthesis of monetary and social transactions to mobile phone records, electronic ticketing, financial payments, routine compilations of network geometry focusing on infrastructure and locational change, and a host of other data from which value can be easily added through synthesis with other data sets. The workshop will focus on urban models that simulate processes involved in transactional flows ranging from physical movements on transportation systems to information flows associated with phone networks to the assembly of economic data associated with markets.

There are clear links to the resilience and sustainability of city systems with regard to travel and interaction as well as to methods for sensing what is happening in real time with respect to policies that are being implemented. These links have been exploited in complexity theory with respect to spatial/geographical scales but they have not been realised in terms of temporal scales. Thus the workshop will focus on linking frequent to less frequent, and routine events to strategic one-off events, and will provide new ways of examining the link between the micro and the macro.

Spatial Price Equilibrium and Food Webs -- Supply Chains in Nature

I continue to be fascinated by networks in nature and have been conducting research at the interfaces of economics, ecology, and operations research.

Specifically, I became intrigued by the underlying economics of predator-prey relationships in complex food webs, which are nature's supply chains.

This research has led to the paper, "Spatial Price Equilibrium and Food Webs: The Economics of Predator-Prey Networks," in which we establish that the governing equilibrium conditions underlying predator-prey interactions with multiple species correspond to the classical spatial price equilibrium conditions dating to the work of the Nobel Laureate in Economic Sciences, Paul Samuelson!

To be able to establish the equivalence between systems in ecology and in economics, as we have done, suggests an inherent commonality among entirely distinct network systems and demonstrates that interactions in ecology and biology can be interpreted economically with price functions and transportation / transaction cost functions. Another fascinating aspect of ecological networks and food webs is that nodes correspond to different species but the flows are common and correspond to biomass flows. So, such networks are single commodity ones!

Our research included the development of a dynamic model of predator-prey interactions using projected dynamical systems theory, a theory and methodology which we developed, and which is now being used in evolutionary game theory by, among others, Bill Sandholm. I just purchased his book and am enjoying reading it. Economists (and others) are fascinated by evolutionary game theory, which has origins in biology, notably, in the work of Maynard Smith. I am delighted that our work has relevance here, as well.

Our paper is to appear in the Proceedings of the 2011 IEEE Conference on Supernetworks and System Management. This conference takes place in Shanghai next week.

Ecological Predator-Prey Networks as Nature's Supply Chains

With the heart-breaking disasters in Japan, and the tremendous human and economic impacts, and, now, with the radiation spreading and various foods from the area surrounding the damaged Fukushima nuclear plant banned for consumption, plus even the water in Tokyo affected, I thought it time to step back and to reflect on nature.

Interestingly, we are increasingly seeing calls for "robustness" and "resiliency" in the context of supply chains since so many from automobile to airline to high tech component ones, including chips, have been adversely affected and seriously disrupted, including the biggest auto manufacturing company in the world, Toyota, because of the triple earthquake-tsunami-nuclear plant disaster that hit Japan, beginning on March 11, 2011, a date that I have sealed in my memory. In addition, journalists are making analogies of supply chains to biological organisms and even the human body and noting how resilient such systems are.

So what are the relationships between biological networks in nature and supply chains? If we can rigorously establish the connections, we should be able to learn how to design more resilient and robust systems, including supply chain networks.

In a recent study, entitled, Dynamics and Equilibria of Ecological Predator-Prey Networks as Nature’s Supply Chains, that I co-authored with the "other" Professor Nagurney, we were able to establish the equivalence between predator-prey ecological networks (think of food chains, for example, as in fisheries, to start) and multitiered supply chains consisting of "agents" who are manufacturers, retailers, or consumers, respectively. What I found fascinating is that in "product" or, shall I say, "corporate" supply chains, one explicitly considers various decision-makers' objective functions, which tend to include the maximization of profits, at least for the manufacturers and the retailers. Moreover, the various decision-makers "compete," whereas in predator-prey ecological networks, competition is clear, but, until now, no-one really quantified prices or value in that context.

In our paper, we established, using a dynamic model of predator prey interactions, that the stationary points or equilibria coincide precisely with those of the equilibria in supply chain networks! The general supply chain model that we used to show this equivalence, which was previously unexplored, was the supply chain network equilibrium model that I developed with Professors June Dong and Ding Zhang and which was published in Transportation Research E in 2002. That model has served as the foundation for numerous extensions; for just a few, click here.

Hence, amazingly, predator-prey interactions have an underlying economics, whereas supply chain networks, in a sense, are ecological predator-prey systems.

The study, Dynamics and Equilibria of Ecological Predator-Prey Networks as Nature’s Supply Chains, expanded on our earlier work that showed the equivalence between bipartite predator-prey networks and classical spatial price equilibrium problems going back to the work of the Nobel Laureate, Paul Samuelson. That paper, "Spatial Price Equilibrium and Food Webs: The Economics of Predator-Prey Networks," I will be presenting at the 2011 IEEE International Conference on Supernetworks and System Management
Shanghai, China, May 29-30, 2011, and it is in press in the Proceedings of that conference.

We became interested in this area of research due to a truly original paper, entitled "NEATS: A Network Economics Approach to Trophic Systems," published in the journal Ecological Modelling, co-authored by a group of researchers based in France: Mullon, Shin, and Cury. The paper applies some of the results in my Network Economics: A Variational Inequality Approach book to formulate and determine equilibria in predator-prey complex webs. One reads regularly about the impact of science on economics but this paper demonstrates how economics and, especially, network economics, can be used to combine both biological constraints that couple biomass balance equations with complementarity principles using Walras' law. The authors investigate the solutions to simple food chains, bilayer networks, complex food webs, and even to cannibalism (the links loop back to the specific nodes in such networks)!