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Dissertations of Doctoral Center Associates

One of the hallmarks of a research university is the production of the next generation of scholars. As Director of the Virtual Center for Supernetworks, I am proud of the students who have worked as Center Associates and whose dissertations I have had the privilege to supervise. The abstracts of their dissertations are below. - Anna Nagurney, John F. Smith Memorial Professor 

Funding for these dissertations has been provided by the National Science Foundation, the AT&T Foundation, the John F. Smith Memorial Fund at the University of Massachusetts, and the Isenberg School of Management at the University of Massachusetts at Amherst. The students gratefully acknowledge this support and thank all those both within and outside the University of Massachusetts, who assisted them in the completion of their dissertations, both professionally and personally.
 

Game Theory for Security Investments in Cyber and Supply Chain Networks

Shivani Shukla, Ph.D., 2017

Anna Nagurney, Chair

Abstract: In a constantly and intricately connected world that is going digital, cybersecurity is imperative to not just the success but also the survival of a business. The ubiquitous digital transformation is fueled by a convulsive growth of devices and data that are leading important innovations in the domain of cyber-physical systems. However, this growth has also enabled internal and external threats to skyrocket, depicting the inherent dichotomy. With an evolving threat landscape, a perpetrator has to be successful once, while the defenders have to continually succeed in fending-off attacks to protect critical infrastructure and digital assets.

The retail and financial sectors are prime targets owing to the large amounts of personal and financial information they process in disperse and distributed environments. One of the biggest retail breaches was that of Target when 30 million credit card numbers and personal information of 70 million customers were stolen and sold on the dark net (Riley and Pagliery (2015)). In the financial sector, JP Morgan Chase lost data of 83 million customers. The accused laudered the $100 million obtained, used 75 shell companies that employed hundreds of people, and 30 fake passports from 17 countries to keep the money hidden (Pagliery (2015)).

Monetization of this sensitive data validates that the motivation of such criminals is principally financial. According to NTT 2016 Global Threat Intelligence Report, retailers are experiencing nearly three times as many cyberattacks as those by financial service providers that were top targets until 2014. Thus, in this dissertation, the focus is, mainly, on the retail and financial sectors, the top two sufferers in the recent past.

Increased sophistication in cyber threats can be attributed to the fact that criminals are now highly skilled, well-funded, coordinated, and organized. As a result, worldwide security breaches are increasing at just about 40% per annum and attackers stay undetected for an average of 200 days. One of the prominent examples of slow detection is the negligence suit led by Yahoo users over a 2014 breach that compromised personal data of 500 million users but was discovered recently in 2016 (Vishwanath (2016)). While large organizations are cautious (JPMorgan doubled its cybersecurity spending to $500 million in 2015; Global information security spending will increase by 36% to $101 billion by 2018 (Purnell (2015))), the small and medium level enterprises are not known for ensuring basic precautionary measures (Forrester (2016)), which stems from their belief that attacks on larger organizations are more consequential. Unfortunately, cyber criminals do not discriminate.

Businesses are facing a barrage of attacks, majority of which have a financial or an espionage motive. In a highly interconnected and mutually dependent world, organizations are constantly interacting and transacting with each other. If one organization in this complex network is breached, there could be ramfications for the others since they might also be vulnerable. Often, attackers circumvent sophistical organizational rewalls and go after soft targets (CNN (2016)). Against the hackers, businesses put forth an asymmetric and myopic struggle.

Organizing funds for proactive and targeted responses requires careful security investment decision-making. In view of the above, a network approach to security investments while evaluating vulnerabilities of the individual organizations and the entire network is essential. Cyber threat cannot be eliminated, rather the culminating risks need to be managed. Investments in stronger defense mechanisms, preventive protocols, cyber intelligence, and agile systems that provide required redundancies or backups could aid in effective risk management.

If threats are rampant in the cyber space, physical supply chain networks are also not exempt from thefts, losses, and damages. In 2015, 1500 incidents of cargo theft, heavy commercial vehicle theft, and identity theft of trucking companies in the United States and Canada was reported. Out of these, in about 470 thefts, cargo and assets worth $98 million were stolen. The average theft loss value per incident was $187,490 (CargoNet(2015)). Some of the principal choke points that attackers manipulate are poor infrastructure and transportation networks, lax port security, and inadequate telecommunications to support tracking devices. Threats can vary by product type, mode of transportation, freight carriers, region, and even day of the week.

In view of the above, this work attempts to answer the following principal questions: (i) For competing firms in a network, what should their security levels be considering their investment costs or budget constraints to ensure a reduction in the entire network's vulnerability? (ii) If firms in a network cooperate, what are the implications on the network vulnerability? Does cooperation yield more economic/financial benefits? (iii) In a supply chain network for high value cargo with competing freight service providers, what should the shipment sizes and security levels be to ensure reduction in vulnerability?

Through this dissertation, I contribute to the modeling and analysis of security investments in cyber and sup- ply chain networks considering network vulnerability also nonlinear budget constraints. The latter contributes significantly to the literature on variational inequality, game theory, and cybersecurity by being methodologically relevant to the application and solution of such problems. I also explore cooperation in terms of cybersecurity among firms in a network, providing a quantitative basis to information sharing to explore its financial and policy related bene ts. This work extends the current literature in the cooperative game theory and cybersecurity domains. In addition, I explore the high value cargo supply chains that are faced with security investment decisions at the freight service providers' level. All the models presented in this dissertation are neither limited to a fixed number of firms or customers, nor to functions of any specific form. Moreover, very few cybersecurity or supply chain security investment models using game theory with competition, network perspective, network vulnerability, nonlinear budget constraints, and cooperation have been solved to-date.

The first part of this dissertation discusses the introduction of and motivation behind this research endeavor, along with a detailed literature review. Next, I discuss the contributions of the work I have undertaken. An overview of relevant methodologies, including variational inequality theory, competitive game theory, cooperative game theory and Nash bargaining theory, and two algorithms used in the chapters to follow is also provided.

Subsequently, I present a supply chain network model in which firms compete on security levels and product flows. The study takes a network approach to cybersecurity investment decision-making to obtain Nash equilibrium and ascertain vulnerabilities of the individual rms and the network on the whole. The model is probabilistic and includes demand side of the network along with its dynamics.

In the next part, a crucial and unique extension to the cybersecurity investment and risk determination model as discussed in the previous part is considered. Nonlinear budget constraints are added to the model that increase its complexity and call for theoretical and methodological contributions.

Thereafter, the cybersecurity investment model is modified to include a cooperative game approach to address the pressing need of collaboration and information sharing among firms in a network through which they can present a more coordinated front against the emerging cyber threat landscape. This inclusion is pivotal to the cybersecurity investment decisions.

Finally, I include my work that advanced modeling of physical security in supply chain networks. My current work in cybersecurity competition and cooperation was leveraged to cater to security investments regarding cargo, infrastructure, and other assets. The model contains features that are innate to physical ows and networks, thereby, marking a distinction from my work in cybersecurity. It deals, primarily, with security investment decisions in the presence of competing freight service providers shipping high value cargo from shipping origins to demand market destination points.

The dissertation is based on the following papers: Nagurney, Nagurney, and Shukla (2015), Nagurney, Daniele, and Shukla (2017), Nagurney and Shukla (2017), and Nagurney, Shukla, Nagurney, Saberi (2017).

Multifirm Models of Cybersecurity Investment Competition vs. Cooperation and Network Vulnerability
Anna Nagurney and Shivani Shukla, European Journal of Operational Research 260(2): (2017), pp 588-600.

A Supply Chain Network Game Theory Model of Cybersecurity Investments with Nonlinear Budget Constraints
Anna Nagurney, Patrizia Daniele, and Shivani Shukla, Annals of Operations Research 248(1): (2017), pp 405-427.

A Supply Chain Game Theory Framework for Cybersecurity Investments Under Network Vulnerability
Anna Nagurney, Ladimer S. Nagurney, and Shivani Shukla, in Computation, Cryptography, and Network Security, N.J. Daras and M.T. Rassias, Editors, Springer International Publishing Switzerland (2015) pp 381-398.

Supply Chain Network Competition in Price and Quality with Multiple Manufacturers and Freight Service Providers
Anna Nagurney, Sara Saberi, Shivani Shukla, and Jonas Floden, Transportation Research E 77: (2015) pp 248-267.

Network Game Theory Models of Services and Quality Competition
with Applications to Future Internet Architectures and Supply Chains

Sara Saberi, Ph.D., 2016

Anna Nagurney, Chair

Abstract: The Internet has transformed the way in which we conduct business and perform economic and financial transactions, communicate and obtain information, and even experience music and entertainment. Customers’ demands, however, are driving the Internet and telecommunication networks towards providing quality-based services. One key challenge in the Internet is the inefficiency of the mechanisms by which technology is deployed and the business and economic models surrounding these processes (Wolf et al. (2014)). Equilibrium models for the Internet generally assume basic economic relationships. However, in new paradigms for the Internet and even in the case of supply chain networks, price is not the only factor but quality of service (QoS) is of increasing importance (Nagurney, Li, Wolf, and Saberi (2013)). The economic complexity associated with designing the future Internet with differentiated services is further advancing the role of pricing models (Jain, Durresi, and Paul (2011)).

Supply chains networks, which give us the means to manufacture the products and deliver them to points of demand across the globe, are also under many pressures to offer differentiated products and services (Nagurney (2014)). It is well-known today that success is determined by how well the entire supply chain performs, rather than the performance of its individual entities. Quality has become one of the most essential factors in the success of supply chain networks (Floden, Barthel, and Sorkina (2010)). However, in todays’ multimodal distribution networks with intense competition among freight service providers, the integration of price and quality competitive behavior has not been examined in a rigorous theoretical and computationally tractable framework.

In this dissertation, I contribute to the analysis, design, and management of the future Internet and supply chain networks with a focus on price and quality competition in serviceoriented networks. This dissertation begins with an introduction, the research motivation for, and a review of the relevant literature, followed by the theoretical foundations of the mathematical framework employed including optimization theory, variational inequality (VI) theory, and projected dynamical systems theory.

In the second part of this dissertation, I focus on economic models for the future Internet. Generally, providers in the Internet face many challenges in determining technical and economic solutions in offering services with different QoS (Wolf et al. (2012)). Key challenges are how to find the equilibrium prices and quality levels in an oligopoly market of service providers in a service-oriented Internet which provides quality-based services. In order to answer this question, I develop both a basic and a general network economic game theory model of a quality-based service-oriented Internet to study the competition among the service providers (both content and network ones) in Chapter 3. I also analyze the effects of the prices that the network providers charge the content providers for data transmission in the basic model.

Moreover, it is imperative to study and analyze the underlying dynamics of the various economic decision-makers involved from content providers to transport network service providers in terms of both pricing as well as quality. In this case, novel insights into the networks’ structures can be obtained by taking into account the associated economic models and equilibrium conditions among providers (Nagurney, Li, Wolf, and Saberi (2013)). In Chapter 4, I, then, develop a dynamic network economic model of a service-oriented Internet with price and quality competition using projected dynamical systems theory. For this model, consumers respond at the demand markets through the demand functions which reflect the attractiveness of the composition of content and network services as reflected by the prices charged and the quality levels.

The pricing of Internet services merely based on quality and data usage, as is now typical, with contracts of one to two years duration can lead to network congestion since network resource utilization may change over time. Furthermore, consumers may desire greater flexibility and more choices. Hence, it is expected that contract duration will become an important feature in the pricing of network services (Hwang and Weiss (2000)). To assess the prices for various contract durations at the demand markets as well as the levels of quality, an economic analysis through a rigorous game theory framework is essential. My approach in Chapter 5 to resolve this void is a game theory model of a service-oriented Internet in which the network providers compete in usage service rates, quality levels, and duration-based contracts, to find the effect of quality and the duration of Internet network contracts on the Internet service pricing.

Furthermore, the growth of intercontinental multi-channel distribution networks has led to fierce competition among freight service providers who are subjected to pricing pressures and increased expectations to handle more complex services (Hakim (2014) and DHL (2014)). In the third part of this dissertation (Chapter 6), I construct a model that captures the competition among manufacturers and freight service providers in a supply chain network. This model is the first one in the literature that handles both price and quality competition with multiple modes of shipment from both equilibrium and dynamic perspectives. The manufacturers compete with one another in terms of price and quality of the product manufactured, whereas the freight service providers compete on price and quality of the transportation service they provide for multiple modes. Both manufacturers and freight service providers maximize their utilities (profits) while considering the consequences of the competitors’ prices and quality levels. Limits on prices and quality levels are included that have relevant policy-related implications.

For each model, I derive the governing equilibrium conditions and provide the equivalent variational inequality formulations. The models presented here are accompanied by a detailed qualitative analysis that provides conditions for existence and uniqueness of equilibrium patterns. In order to illustrate the modeling framework and the algorithm, I present computed solutions to several numerical examples for each model as well as sensitivity analysis results.

This dissertation is heavily based on the following papers: Saberi, Nagurney, and Wolf (2014), Nagurney, Li, Saberi, and Wolf (2014), Nagurney, Saberi, Wolf, and Nagurney (2015), and Nagurney, Saberi, Shukla, and Floden (2015) as well as additional results and conclusions.

This research was supported, in part, by the National Science Foundation (NSF) grant CISE #1111276, for the NeTS: Large: Collaborative Research: Network Innovation Through ChoiceNet project awarded to the University of Massachusetts Amherst. This support is gratefully acknowledged.

A Network Economic Game Theory Model of a Service-Oriented Internet with Price and Quality Competition in Both Content and Network Provision
Sara Saberi, Anna Nagurney, and Tilman Wolf, Service Science 6(4): December (2014) pp 229-250.

A Dynamic Network Economic Model of a Service-Oriented Internet with Price and Quality Competition
Anna Nagurney, Dong Li, Sara Saberi, and Tilman Wolf, in Network Models in Economics and Finance, V.A. Kalyagin, P.M. Pardalos, and T. M. Rassias, Editors, Springer International Publishing Switzerland (2014) pp 239-264.

A Game Theory Model for a Differentiated Service-Oriented Internet with Duration-Based Contracts
Anna Nagurney, Sara Saberi, Tilman Wolf, and Ladimer S. Nagurney, Proceedings of ICS 2015: Operations Research and Computing: Algorithms and Software for Analytics, Brian Borchers, J. Paul Brooks, and Laura McLay, Editors, INFORMS (2015) pp 15-29.

Supply Chain Network Competition in Price and Quality with Multiple Manufacturers and Freight Service Providers
Anna Nagurney, Sara Saberi, Shivani Shukla, and Jonas Floden, Transportation Research E 77: (2015) pp 248-267.

Quality Competition in Supply Chain Networks with Applications to Information Asymmetry, Product Differentiation, Outsourcing, and Supplier Selection

Dong "Michelle" Li, Ph.D., 2015

Anna Nagurney, Chair

Abstract: The quality of the products produced and delivered in supply chain networks is essential for consumers' safety, well-being, and benefits, and for firms' profitability and reputation. However, because of the complexity of today's large-scale highly globalized supply chain networks, along with issues such as the growth in outsourcing and in global procurement, as well as the information asymmetry associated with quality, supply chain networks are more exposed to both domestic and international quality failures.

In this dissertation, I contribute to the equilibrium and dynamic modeling and analysis of quality competition in supply chain networks under scenarios of information asymmetry, product differentiation, outsourcing, and under supplier selection.

The first part of the dissertation consists of a review of the relevant literature, the research motivation, and an overview of methodologies.

The second part of the dissertation formulates quality competition with minimum quality standards under the scenario of information asymmetry, specifically, when there is no product differentiation by brands or labels.

In the third part, in contrast, quality competition is modeled under product differentiation, when firms engage in distinguishing their products from their competitors'.

The fourth part concentrates on quality competition in supply chain networks with outsourcing. The models yield the optimal make-or-buy and contractor selection decisions for the firm(s) and the optimal pricing and quality decisions for the contractors. The impacts of firms' attitudes towards disrepute are also studied numerically.

In the fifth part, a multitiered supply chain network model of quality competition with suppliers is developed. It consists of competing suppliers and competing firms who purchase components for the assembly of their products and, if capacity permits, produce their own components. The optimal supplierselection decisions, optimal component production and quality, and the optimal quality preservation levels of the assembly processes are provided. Such issues as the values of the suppliers to the firms, the impacts of capacity disruptions, and the potential investments in capacity enhancements are explored numerically.

The models and analysis in this dissertation can be applied to numerous industries, ranging from the food industry to the pharmaceutical industry, automobile industry, and to the high technology industry.


A Supply Chain Network Game Theory Model with Product Differentiation, Outsourcing of Production and Distribution, and Quality and Price Competition
Anna Nagurney and Dong Li, Annals of Operations Research 228(1), (2015) pp 479-503.

Equilibria and Dynamics of Supply Chain Network Competition with Information Asymmetry in Quality and Minimum Quality Standards
Anna Nagurney and Dong Li, Computational Management Science 11(3): (2014) pp 285-315.

A Dynamic Network Oligopoly Model with Transportation Costs, Product Differentiation, and Quality Competition
Anna Nagurney and Dong Li, Computational Economics 44(2): (2014) pp 201-229.

Pharmaceutical Supply Chain Networks with Outsourcing Under Price and Quality Competition
Anna Nagurney, Dong Li, and Ladimer S. Nagurney, International Transactions in Operational Research 20(6): (2013) pp 859-888.

Supply Chain Management of Perishable Products with Applications to Healthcare

Amir H. Masoumi, Ph.D., May 2013

Anna Nagurney, Chair

Abstract: Supply chains for time-sensitive products, and, in particular, for perishable products, pose specific and unique challenges. By de nition, a perishable product has a limited lifetime during which it can be used, after which it should be discarded (Federgruen, Prastacos, and Zipkin (1986)).

In this dissertation, I contribute to the analysis, design, and management of supply chain networks for perishable products with applications to healthcare. Specifically, I construct generalized network frameworks to capture perishable product supply chains in healthcare operating under either centralized or decentralized decision-making behavior. The dissertation is motivated by applications ranging from blood supply chains to pharmaceuticals, such as vaccines and medicines. The novelty of the modeling and computational framework includes the use of arc mul tipliers to capture the perishability of the healthcare product(s), along with waste
management costs, and risk.

The first part of the dissertation consists of a literature review of perishable product supply chains with a focus on healthcare along with an overview of the relevant methodologies.

The second part of the dissertation formulates supply chains in healthcare operating under centralized decision-making behavior. In this part, I focus on both the operations management of and the sustainable design of blood supply chains and construct models for regionalized blood banking systems as belonging to the Red Cross.

The third part of the dissertation considers competitive behavior, with a focus on the pharmaceutical industry. I construct an oligopoly supply chain network model, with differentiated brands to capture the competition among producers of substitutable drugs using game theory and variational inequality theory. Furthermore, using a case study based on real-world scenarios of a highly popular cholesterol-reducing branded drug, the impact of patent rights expiration of that brand is explored which coincides the time when its equivalent generic emerges into the markets. The calculated results are then compared to the observations from the real-word problem.

Finally, the projected dynamical system formulation of the pharmaceutical network oligopoly model is derived.

This dissertation is based on the following papers: Nagurney, Masoumi, and Yu (2012), Nagurney and Masoumi (2012), and Masoumi, Yu, and Nagurney (2012) as well as additional results and conclusions.

Supply Chain Network Operations Management of a Blood Banking System with Cost and Risk Minimization
Anna Nagurney, Amir H. Masoumi, and Min Yu, Computational Management Science 9(2): (2012) pp 205-231.

A Supply Chain Generalized Network Oligopoly Model for Pharmaceuticals Under Brand Differentiation and Perishability
Amir H. Masoumi, Min Yu, and Anna Nagurney, Transportation Research E 48: (2012), pp 762-780.

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 (2012), T. Boone, V. Jayaraman, and R. Ganeshan, Editors, Springer, London, England, pp 49-72.

 

Analysis, Design, and Management of Supply Chain Networks
with Applications to Time-Sensitive Products

Min Yu, Ph.D., May 2012

Anna Nagurney, Chair

Abstract: With supply chains spanning the globe, and with increasing time-sensitivity for various products in many markets, timely deliveries are becoming a strategy, as important as productivity, quality, and even innovation (see, e.g., Gunasekaran, Patel, and McGaughey (2004), Christopher (2005), and Nagurney (2006)).

A product is considered to be time-sensitive, if there is a strict time requirement regarding that product, either as a characteristic of the product itself or on the demand side. In particular, a time-sensitive product must have at least one of the following two properties:

  • the product loses its value rapidly, due to either obsolescence or perishability, which can lead to extra waste and cost, if unused;
  • the demand for it is sensitive to the elapsed time for the order ful llment; the failure to satisfy the demand on-time may result in the loss of potential market share, or, even worse, additional injuries or death as in times of crises.

This dissertation formulates, analyzes, and solves a spectrum of supply chain network problems for time-sensitive products, ranging from fast fashion to food to pharmaceuticals. Specifically, I first develop a model that captures the trade-offs between the operational costs and time issues in the apparel industry. I then construct a sustainable fashion supply chain network model under oligopolistic competition and brand differentiation. I, subsequently, capture the deterioration of fresh produce along the entire supply chain through arc mul- tipliers with time decay. Finally, I consider the supply chain network design problem for critical needs products, as in times of crises and humanitarian relief operations. I also develop a supply chain network design/redesign model with multiple products, with particular relevance to healthcare.

This dissertation consists of advances in the modeling, analysis, and design of supply chain networks for time-sensitive products, all uni ed through the methodology of varia- tional inequality theory (see Nagurney (1999)), coupled with network theory and multicri- teria decision-making. The framework captures the underlying behavior associated with the operation and management of the associated supply chains, whether that of central optimization or competition, allows for the graphical depiction of the supply chain network structures, and efficient and effective solution.

Competitive Food Supply Chain Networks with Application to Fresh Produce
Min Yu and Anna Nagurney

Multiproduct Humanitarian Healthcare Supply Chains: A Network Modeling and Computational Framework
Anna Nagurney, Min Yu, and Qiang Qiang, in the Proceedings of the 23rd Annual POMS Conference, Chicago, Illinois, April 20-23, 2012.

A Supply Chain Generalized Network Oligopoly Model for Pharmaceuticals Under Brand Differentiation and Perishability
Amir H. Masoumi, Min Yu, and Anna Nagurney, Transportation Research E 48: (2012), pp 762-780.

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.

Supply Chain Network Operations Management of a Blood Banking System with Cost and Risk Minimization
Anna Nagurney, Amir H. Masoumi, and Min Yu, to appear in Computational Management Science.

Fashion Supply Chain Management Through Cost and Time Minimization from a Network Perspective
Anna Nagurney and Min Yu, in Fashion Supply Chain Management: Industry and Business Analysis (2011), T.M. Choi, Editor, IGI Global, Hershey, PA, pp 1-20.

Supply Chain Network Design for Critical Needs with Outsourcing
Anna Nagurney, Min Yu, and Qiang Qiang, Papers in Regional Science 90: (2011) pp 123-142.


Sustainable Supply Chains:
Multicriteria Decision-Making and Policy Analysis for the Environment

Trisha Woolley, Ph.D., February 2010

Anna Nagurney, Chair

Abstract: It is believed that the critical next step from examinations of operations and the environment is the study of sustainability nd supply chains (Linton, Klassen, and Jayaraman (2007)). Environmental quality and preservation as well as meeting the stress of emission reductions is rapidly becoming an important isue for public policy (Wilkinson, Hill, and Gollan (2001)). However, Lambertini and Mantovani (2007) note the disregard, unrelated to regulatory requirements, of research practitioners to the potential benefits of appropriate competition policy measures and consumer pressures (Srivastara (2007)). In addition, a firm's success, notably, in terms of financial and/or environmental practices, has been tied, in part, to the strength of its ability to coordinate and integrate activities along the entire supply chain (Spekman, Kamauff Jr., and Myhr (1998)), and to effectively implement multicriteria decision-making tools to aid in their strategic decisions.

I present five essays in this dissertation. For each model I utilize the theory of variational inequalities, derive the formulation, present qualitative properties, and provide numerical examples. The first essay develops the multitiered sustainable supply chain network model with multicriteria decision-making. In the second essay I construct a modeling and computational framework that allows for the determination of optimal carbon taes applied to electric power plants in the context of electric power supply chain generation / distribution/ consumption) networks. The third essay considers electric power supply chain networks and develops a model of tradable pollution permits in the case of multiple pollutants and spatially distinct receptor points. In the fourth essay, I quantify and assess, from a system-optimized sustainable supply chain network perspective, the environmental effects resulting when a horizontal supply chain integration occurs. In the fifth and final essay, I extend the work of Nagurney (2009) to the multiproduct supply chain network domain to quantify the impacts.

This dissertation is heavily based on the following papers: Nagurney, Liu, and Woolley (2006), Nagurney, Liu, and Woolley (2007), Woolley, Nagurney, and Stranlund (2009), Nagurney and Woolley (2009) and Nagurney, Woolley, and Qiang (2009).

Multiproduct Supply Chain Horizontal Network Integration: Models, Theory, and Computational Results
Anna Nagurney, Trisha Woolley, and Qiang Qiang, International Transactions in Operational Research 17: (2010) pp 333-349.

Spatially Differentiated Trade of Permits for Multipollutant Electric Power Supply Chains
Trisha Woolley, Anna Nagurney, and John Stranlund, in Optimization in the Energy Industry (2009), J. Kallrath, P. Pardalos, S. Rebennack, and M. Scheidt, Editors, Springer, Berlin, Germany, pp. 277-296.

Sustainable Supply Chain and Transportation Networks
Anna Nagurney, Zugang Liu, and Trisha Woolley,  International Journal of Sustainable Transportation
1: (2007) pp 29-51.

Optimal Endogenous Carbon Taxes for Electric Power Supply Chains with Power Plants
Anna Nagurney, Zugang Liu, and Trisha Woolley, Mathematical and Computer Modelling 44: (2006) pp 899-916.

Internet Voting: Beyond Technology
Trisha Woolley and Craig Fisher, Information Security & Ethics: Social & Organizational Issues, Marian Quigley, Editor, IRM Press, Pennsylvania (2005).

I-voting:  To Have or Not to Have?
Trisha Woolley and Craig Fisher, Information Technology & Organizations: Trends, Issues, Challenges & Solutions 1: (2003) 144-146.
Network Efficiency/Performance Measurement with Vulnerability and Robustness Analysis with Application to Critical Infrastructure

Qiang "Patrick" Qiang, Ph.D., May 2009

Anna Nagurney, Chair

Abstract: The recent theories of scale-free and small-world networks have significantly enhanced our understanding of the behavior as well as the vulnerability of many real-world networks. However, the majority of network vulnerability studies focus solely on the topological characteristics. Although the topological structure of a network provides crucial information regarding network vulnerability, the flow on a network is also an important indicator, as are the flow-induced costs and the behavior of the users.

Latora and Marchiori (2001, 2002, 2004) proposed a network efficiency measure that is shown to have advantages over several existing network measures. Nevertheless, their measure only considers geodesic information and, therefore, ignores important factors such as flows, costs, and behaviors.

The first objective of this dissertation is to construct a network efficiency/performance measure that extends the Latora-Marchiori measure to incorporate such important network factors as flows, costs, and behaviors in order to assess the importance of network components. It is shown that the new network measure has advantages over several existing network measures. Furthermore, the measure is able to handle both fixed and elastic demands as well as static and dynamic networks, with the latter of particular relevance to the Internet. Moreover, it enables a ranking of the importance of network components.

In addition, instead of looking at the situation where a network component is completely disrupted, network robustness, another important aspect of the network vulnerability, investigates cases in which network resources are reduced in stressful environments. The second goal of this dissertation is to study transportation network robustness based on the new network efficiency/performance measure in order to investigate the network functionality when the links are partially degraded. I also evaluate transportation network robustness under different user behaviors and with environmental concerns.

Furthermore, based on the recent results regarding the supernetwork equivalence between transportation networks and supply chain networks as well as financial networks (Nagurney (2006a) and Liu and Nagurney (2007)), I apply the new network measure to study multitiered financial networks with intermediation. I also propose a novel supply chain model with disruption risks and uncertain demands and define a weighted supply chain network performance measure.

Fragile Networks: Identifying Vunerabilities and Synergies in an Uncertain World
Anna Nagurney and Qiang Qiang, John W. Wiley & Sons, 2009.

A Relative Total Cost Index for the Evaluation of Transportation Network Robustness in the Presence of Degradable Links and Alternative Travel Behavior
Anna Nagurney and Qiang Qiang, International Transactions in Operational Research 16: (2009) pp 49-67.

An Efficiency Measure for Dynamic Networks Modeled as Evolutionary Variational Inequalities with Application to the Internet and Vulnerability Analysis
Anna Nagurney and Qiang Qiang, Netnomics 9: (2008) pp 1-20.

Identification of Critical Nodes and Links in Financial Networks with Intermediation and Electronic Transactions
Anna Nagurney and Qiang Qiang in Computational Methods in Financial Engineering, E. J. Kontoghiorghes, B. Rustem, and P. Winker, Editors, Springer, Germany (2008).


A Unified Network Performance Measure with Importance Identification and the Ranking of Network Components
Qiang Qiang and Anna Nagurney, Optimization Letters
2: (2008) pp 127-142.

A Network Efficiency Measure with Application to Critical Infrastructure Networks
Anna Nagurney and Qiang Qiang, Journal of Global Optimization
40: (2008) pp 261-275.

A Network Efficiency Measure for Congested Networks
Anna Nagurney and Qiang Qiang, Europhysics Letters
79: (2007) 38005, pp 1-5.

Robustness of Transportation Networks Subject to Degradable Links
Anna Nagurney and Qiang Qiang, Europhysics Letters 80: (2007) 68001, pp 1-6.


A Transportation Network Efficiency Measure that Captures Flows, Behavior, and Costs with Applications to Network Component Importance Identification and Vulnerability
Anna Nagurney and Qiang Qiang, Proceedings of the POMS 18th Annual Conference, May 4 to May 7, 2007.

Transportation and Dynamic Networks: Models, Theory, and Applications to Supply Chains, Electric Power, and Financial Networks

Zugang Liu, Ph.D., May 2008

Anna Nagurney, Chair

Abstract: Network systems, including transportation and logistic systems, the Internet, electric power generation and distribution networks as well as financial networks, provide the critical infrastructure for the functioning of our societies and economies. The understanding of the dynamic behavior of such systems is also crucial to national security and prosperity. The identification of new connections between distinct network systems is the inspiration for the research in this dissertation. In particular, I answer two questions raised by Beckmann, McGuire, and Winsten (1956) and Copeland (1952) over half a century ago, which are, respectively, how are electric power flows related to transportation flows and does money flow like water or electricity? In addition, in this dissertation, I achieve the following:
1. I establish the relationships between transportation networks and three other classes of complex network systems: supply chain networks, electric power generation and distribution networks, and financial networks with intermediation. The establishment of such connections provides novel theoretical insights as well as new pricing mechanisms, and efficient computational methods.
2. I develop new modeling frameworks based on evolutionary variational inequality theory that capture the dynamics of such network systems in terms of the time-varying flows and incurred costs, prices, and, where applicable, profits. This dissertation studies the dynamics of such network systems by addressing both internal competition and/or cooperation, and external changes, such as varying costs and demands.
3. I focus, in-depth, on electric power supply chains. Electric power supply chains are some of the most dynamic network systems due to the fluctuations in demand for electricity and the associated
generation/transmission costs (http://www.eia.doe.gov/). Furthermore electricity transmission systems, similar to urban transportation networks, have been increasingly characterized by congestion problems due to heavy loads (cf. Singh et al. (1998) and Chao et al. (2000)). Hence, the understanding of dynamic electric power supply chains with fluctuating costs and demands is of great interest to a variety of decision-makers as well as to consumers (see, e.g., Ruff (2002), Borenstein (2005)). Moreover, the undergoing deregulation process has caused profound changes in the electric power industry, which requires a thorough identification of the structure of the emerging electric power supply chains (cf. Nagurney (2006), Matsypura, Nagurney, and Liu (2007), and Nagurney, Liu, Cojocaru, and Daniele (2007)).
An Integrated Electric Power Supply Chain and Fuel Market Network Framework: Theoretical Modeling with Empirical Analysis for New England Zugang Liu and Anna Nagurney

Dynamic Electric Power Supply Chains and Transportation Networks: An Evolutionary Variational Inequality Formulation Anna Nagurney, Zugang Liu, Monica-Gabriela Cojocaru, and Patrizia Daniele, Transportation Research E 43: (2007) pp 624-646.

Financial Networks with Intermediation and Transportation Network Equilibria: A Supernetwork Equivalence and Reinterpretation of the Equilibrium Conditions with Computations Zugang Liu and Anna Nagurney, Computational Management Science 4: (2007) pp 243-281.

Sustainable Supply Chain and Transportation Networks Anna Nagurney, Zugang Liu, and Trisha Woolley, International Journal of Sustainable Transportation 1: (2007) pp 29-51.

Modeling of Electric Power Supply Chain Networks with Fuel Suppliers via Variational Inequalities Dmytro Matsypura, Anna Nagurney, and Zugang Liu,  International Journal of Emerging Electric Power Systems Vol. 8: Iss. 1: (2007) Article 5. Link to online article.

An Evolutionary Variational Inequality Formulation of Supply Chain Networks with Time-Varying Demands Anna Nagurney and Zugang Liu, in Network Science, Nonlinear Science and Dynamic Game Theory Applied to the Study of Infrastructure Systems, T.  L. Friesz, Editor, Springer, Berlin, Germany  (2007) pp 267-302.

A Dynamic Theory for the Integration of Social and Economic Networks
with Applications to Supply Chain and Financial Networks

Tina Wakolbinger, Ph.D., May 2007

Anna Nagurney, Chair

Abstract: Uzzi (1996, p. 674) highlighted that there is a "growing need to understand how social structure assists or impedes economic performance." In this dissertation, I contribute to this understanding by constructing dynamic supernetwork models that  explicitly integrate social networks with economic network models and that rigorously capture the role that relationship levels play.

The research in this dissertation is motivated by the growing literature that empirically and theoretically highlights the importance of relationships in supply chains (cf. Cannon and Perreault (1999), Bernardes and Fensterseifer (2004), and Baker and Faulkner (2004)) and financial transactions (cf. Berger and Udell (1995), Anthony (1997), and Uzzi (1999)). As this literature shows, the existence of appropriate social networks can affect not only the risk associated with the  transactions but also transaction costs.

By explicitly including the role that relationships play in economic transactions, I extend the previous research on supply chain network models (see, for example, Nagurney, Dong, and Zhang (2002), Nagurney, Cruz, and Matsypura (2003), and Nagurney and Matsypura (2005)). Furthermore, I extend the literature on financial network  models (see, for example, Nagurney and Ke (2001, 2003) and Nagurney and Cruz (2003a,b, 2004)).

Specifically, I first develop a model consisting of an integrated supply chain and social network. I then construct a model consisting of an integrated financial and social network. Finally, I extend both these models to an international setting. The social networks consist of relationships of different strength as they have been described in the papers by Granovetter (1973), Freeman, Borgatti, and White (1991), and Golicic, Foggin, and Mentzer (2003).

The supernetwork models describe how the behavior of the  multicriteria decision-makers and induced flows influence the co-evolution of social and economic networks. Numerical examples highlight the unique ability of this framework to analyze the interaction between the social network and the economic network. The models are based on variational inequality theory for the study of the equilibrium states  (cf. Nagurney (1999)) and projected dynamical systems theory for the study of the associated dynamics (cf. Nagurney and Zhang (1996a))
Dynamic Supernetworks for the Integration of Social Networks and Supply Chains with Electronic Commerce: Modeling and Analysis of Buyer-Seller Relationships with Computations Tina Wakolbinger and Anna Nagurney,  Netnomics 6: (2004) pp 153-185.

Supernetworks: An Introduction to the Concept and its Applications with a Specific Focus on Knowledge Supernetworks Anna Nagurney and Tina Wakolbinger,  International Journal of Knowledge, Culture and Change Management 4: (2004) pp 1523-1530.

On a Paradox of Traffic Planning, translated from the (1968) original D. Braess paper from German to English by D. Braess, A. Nagurney, and T. Wakolbinger , Transportation Science 39: (2005) pp 446-450.

Financial Engineering of the Integration of Global Supply Chain Networks and Social Networks with Risk Management Jose M. Cruz, Anna Nagurney, and Tina Wakolbinger,  Naval Research Logistics 53: (2006), pp 674-696.

The Co-Evolution and Emergence of Integrated International Financial Networks and Social Networks: Theory, Analysis, and Computations Anna Nagurney, Jose M. Cruz, and Tina Wakolbinger  (
Invited chapter for Globalization and Regional Economic Modeling, edited by R. Cooper, K. P. Donaghy,  G. J. D. Hewings, Springer.)

The Evolution and Emergence of Integrated Social and Financial Networks with Electronic Transactions: A Dynamic Supernetwork Theory for the Modeling, Analysis, and Computation of Financial Flows and Relationship Levels Anna Nagurney, Tina Wakolbinger, and Li Zhao ,  Computational Economics 27
: (2006) pp 353-393.

Dynamics of Global Supply Chain and Electric Power Networks:
Models, Pricing Analysis, and Computations

Dmytro Matsypura, Ph.D., September 2006

Anna Nagurney, Chair

Abstract: The electric power industry in the United States and in other countries is undergoing profound regulatory and operational changes. The underlying rationale behind these transformations is to move once highly monopolized vertically-integrated industry from a centralized operation approach to a competitive one. The deregulation process in the US has had a dramatic effect on the US power market. It has led, in particular, to a significant increase in the number of market participants and changes to electricity trading patterns, making system reliability more difficult to maintain. The vulnerability of the system was clearly illustrated on August 14, 2003 with the occurrence of the largest blackout in the history of the US. As an indicator of the US electric power system's fragility and unreliability, the event made imperative a dialogue on how the electric power industry could be improved. This dissertation joins this current dialogue.

In this dissertation, I develop a new theoretical framework for the modeling, pricing analysis, and computation of solutions to electric power supply chains with power generators, suppliers, transmission service providers, and the inclusion of consumer demands. In particular, I advocate the application of finite-dimensional variational inequality theory, projected dynamical systems theory, game theory, network theory, and other tools that are have been recently proposed for the modeling and analysis of supply chain networks (cf. Nagurney (2006)) to electric power markets.

This dissertation contributes to the extant literature on the modeling, analysis, and solution of  supply chain networks, including global supply chains, in general, and electric power supply chains, in particular, in the following ways. It develops a theoretical framework for modeling, pricing analysis, and computation of electric power flows/transactions in electric power systems using the rationale for supply chain analysis. The models developed include both static and dynamic ones. The dissertation also adds a new  dimension to the methodology of the theory of projected dynamical systems by proving that, irrespective of the speeds of adjustment, the equilibrium of the system remains the same. Finally, I include alternative fuel (renewable and nonrenewable) suppliers, along with their behavior into the supply chain modeling and analysis framework.

This dissertation has strong practical implications. In an era in which technology and globalization, coupled with increasing risk and uncertainty, complicate electricity demand and supply within and between nations, the successful management of electric power systems and pricing become increasingly pressing topics with relevance not only for economic prosperity but also national security. This dissertation addresses such related topics by providing models, pricing tools, and algorithms for decentralized electric power supply chains. This dissertation is based heavily on the following co-authored papers: Nagurney, Cruz, and Matsypura (2003), Nagurney and Matsypura (2004, 2005, 2006), Matsypura and Nagurney (2005), Matsypura, Nagurney, and Liu (2006).
A Supply Chain Network Perspective for Electric Power Generation, Supply, Transmission, and Consumption  Anna Nagurney and Dmytro Matsypura (To appear in Advances in Computational Economics, Finance and Management Science, E. Kontogiorghes and C. Gatu, Editors, Springer (2006); appears in condensed form in the Proceedings of the International Conference on Computing, Communications and Control Technologies, Austin, Texas, Volume VI: (2004) pp 127-134.)

Global Supply Chain Network Dynamics with Multicriteria Decision-Making Under Risk and Uncertainty
Anna Nagurney and Dmytro Matsypura,  Transportation Research E 41: (2005) pp 585-612.

Dynamics of Global Supply Chain Supernetworks  Anna Nagurney, Jose Cruz, and Dmytro Matsypura ,  Mathematical and Computer Modelling 37: (2003) pp 963-983.
UNIFIED COMPLEX NETWORK FRAMEWORK
FOR ENVIRONMENTAL DECISION-MAKING WITH APPLICATIONS TO
GREEN LOGISTICS AND ELECTRONIC WASTE RECYCLING 

Fuminori Toyasaki, Ph.D., September 2005

Anna Nagurney, Chair

Abstract: In this dissertation, I developed a unified complex network framework for environmental decision-making. I focused on complex network systems arising in the context of green logistics, including global supply chains, and electronic waste recycling. The framework that I developed is able to handle many decision-makers at the tiers of the networks, and enables the prediction of the flows of the materials between tiers as well as the prices at the tiers, along with the emissions generated, and the incurred costs and profits.

I first developed a theoretical framework for supply chain networks with environmental concerns in the context of decision-making in the Information Age today. I allowed different decision-makers to weight the criteria (including the environmental ones) in distinct fashion. Subsequently, I generalized the original model to a global supply chain network model which included environmental criteria, electronic commerce, and risk management.

I then developed an integrated reverse supply chain management framework that allows for the modeling, analysis, and computation of the material flows as well as the prices associated with the different tiers in the multitiered electronic recycling network. I also extended this model in order to deal with the environmental risk caused by hazardous material generated from the recycling processes. I assumed that the environmental risk due to hazardous material depends on the amount of residual hazardous material that is not extracted from electronic wastes by the processor as well as on the storage amount of hazardous waste that is not disposed yet by the hazardous material disposer.

The models and computational methods were based on the methodologies of variational inequality theory for the study of the statics (cf. Nagurney (1999)) and projected dynamical systems for the dynamics (cf. Nagurney and Zhang (1996)). 

Electronic Waste Management and Recycling: A Multitiered Network Equilibrium Framework for E-Cycling Anna Nagurney and Fuminori Toyasaki  (Appears in revised form and under new title, "Reverse Supply Chain  Management and Electronic Waste  Recycling: A Multitiered Network  Equilibrium Framework for E-Cycling," in  Transportation Research E: Transportation and Logistics (2005).) 

Supply Chain Supernetworks and Environmental Criteria  Anna Nagurney and Fuminori Toyasaki, Transportation Research D 8: (2003) pp 185 - 213.

STATICS AND DYNAMICS OF COMPLEX NETWORK SYSTEMS: SUPPLY CHAIN ANALYSIS AND FINANCIAL NETWORKS WITH INTERMEDIATION

Ke Ke, Ph.D., September 2004

Anna Nagurney, Chair

Abstract: In this dissertation, I considered various novel extensions of network equilibrium problems both in static and in dynamic settings from modeling, qualitative analysis, and computational perspectives. For each problem, I identified the network structure, described the behavior of the network agents involved, presented the formulations, derived the equilibrium conditions, established the qualitative properties, and proposed the appropriate algorithm for computations. A variety of numerical examples were provided for illustration of the models presented. First, I proposed a multilevel network perspective for the conceptualization of the dynamics underlying supply chains in the presence of competition. Rather than being formulated over a single network, as was done by Nagurney, Dong, and Zhang (2002) and Nagurney et al (2002), who proposed static models of supply chain networks under competition, the multilevel network consisted of: the logistical network, the informational network, and the financial network. The network agents, in turn, consisted of the manufacturers, the retailers, and the consumers located at the demand markets. Next, I studied financial network equilibrium problems with intermediation in a static setting and described the disequilibrium dynamics as well.  I considered an economy consisting of three types of agents: those with sources of funds, intermediaries, and the consumers located at demand markets corresponding to the uses of funds. Subsequently, I generalized the modeling framework to incorporate the impact of electronic transactions on the financial networks with intermediation. The modeling framework captured both competition and cooperation, and included transaction costs which brought a greater degree of realism to the study of financial intermediation. In order to capture the influence of the decision-makers' risk attitudes upon the financial network equilibrium, I further developed a value function approach in which the risk for each decision-maker was penalized by a variable weight. The models and computational methods were based on the methodologies of variational inequality theory for the study of the statics (cf. Nagurney (1999)) and projected dynamical systems for the dynamics (cf. Nagurney and Zhang (1996)). I concluded this dissertation with a summary of the modeling framework developed and provided suggestions for possible future extensions.
 
Financial Networks with Intermediation: Risk Management with Variable Weights  Anna Nagurney and Ke Ke,  European Journal of Operational Research.

Financial Networks with Electronic Transactions: Modeling, Analysis, and Computations
Anna Nagurney and Ke Ke , Quantitative Finance 3: (2003) pp 71-87.

Dynamics of Supply Chains: A Multilevel (Logistical/Informational/Financial) Network Perspective
Anna Nagurney, Ke Ke, Jose Cruz, Kitty Hancock, and Frank Southworth,  Environment and Planning B 29: (2002) pp 795-818.

Dynamics of Financial Networks with Intermediation  Anna Nagurney and Ke Ke
INTERNATIONAL FINANCIAL NETWORKS AND GLOBAL SUPPLY CHAINS:
A UNIFIED FRAMEWORK FOR DECISION-MAKING, OPTIMIZATION, AND
RISK MANAGEMENT

Jose M. Cruz, Ph.D., May 2004

Anna Nagurney, Chair

Abstract: In this dissertation, I developed a unified framework for the modeling, analysis, and computation of solutions to both international financial problems with intermediation as well as to global supply chains through the medium of networks. The framework that I developed can handle as many decision-makers within each country as needed (be they sources of funds, financial intermediaries, or, as in the case of global supply chains: manufacturers, retailers, and/or distributors, as well as consumers), and enables the prediction of the flows (financial and product) between tiers of the networks as well as the prices at the tiers. In addition, I considered not only physical transactions between decision-makers but also virtual ones in the form of electronic transactions. I utilized tools from both management science and finance to identify the commonality in the structures of international financial networks and global supply chains. I modeled the behavior of the various decision-makers, which allows for multiple criteria such as profit maximization as well as risk minimization, and study the dynamics of the various interactions. The analysis was both qualitative in nature as well as computational. The effectiveness of the proposed methodologies was demonstrated through numerous examples. The research in this dissertation was motivated not only by the practical importance of the topic but also by the need to develop rigorous theoretical frameworks for complex decision-making on networks with an international focus. To-date, there have been many innovative models developed for multi-tiered networks.  For example, Nagurney and Ke (2001, 2003) focused on financial multitiered networks with intermediation (with and without electronic transactions). Moreover, Nagurney, Dong, and Zhang (2002), Nagurney, Loo, Dong, and Zhang (2002), and Nagurney, Ke, Cruz, Hancock, and Southworth (2002) developed models for multitiered supply chains. All the above research has been centered on a single country.  In this thesis, I captured such decision-making but in a multiple country, multiple currency context with enhanced risk management.
 
Supply Chain Networks, Electronic Commerce, and Supply Side and Demand Side Risk Anna Nagurney, Jose Cruz, June Dong, and Ding Zhang , European Journal of Operational Research.

Statics and Dynamics of Global Supply Chain Networks with Environmental Decision-Making
Anna Nagurney, Jose Cruz, and Fuminori Toyasaki (Prepared for the 9th Workshop on Economics and Heterogeneous Interacting Agents, Kyoto University, Kyoto, Japan, May 27-29, 2004.)
 
Global Supply Chain Networks and Risk Management  Anna Nagurney, Jose Cruz, and June Dong

Dynamics of International Financial Networks with Risk Management  Anna Nagurney and Jose Cruz , Quantitative Finance 4: (2004) pp 276-291.

International Financial Networks with Electronic Transactions  Anna Nagurney and Jose Cruz,  Innovations in Financial and Economic Networks, Anna Nagurney, editor, Edward Elgar Publishing, 2003, pp 136-168.

International Financial Networks with Intermediation: Modeling, Analysis, and Computations Anna Nagurney and Jose Cruz, Computational Management Science 1: (2003) pp 31-58.

Dynamics of Global Supply Chain Supernetworks  Anna Nagurney, Jose Cruz, and Dmytro Matsypura,  Mathematical and Computer Modelling 37: (2003) pp 963-983.

Dynamics of Supply Chains: A Multilevel (Logistical/Informational/Financial) Network Perspective
Anna Nagurney, Ke Ke, Jose Cruz, Kitty Hancock, and Frank Southworth,  Environment and Planning B 29: (2002) pp 795-818.

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