Modeling smart cities with hetero-functional graph theory

In the 21st century, urbanization as a mega-trend will create many megacities. These highly dense, large population centers will have to efficiently deliver essential services including, energy, water, mobility, manufactured goods, and healthcare. While these services may be treated independently, they are in reality interdependent, especially as the need for efficient resource utilization, and consequently integration. This presents a formidable engineering challenge as the modeling foundations for these services have traditionally been discipline specific. Furthermore, efforts to integrate these modeling foundations have often adopted simplifying constraints which have limited applicability to the emerging challenge of smart cities. This paper collates an emerging "hetero-functional graph theory" for potential application to integrated smart city infrastructure models. It has been recently demonstrated in several application domains. The paper concludes with the construction of a hetero-functional graph for a smart city model consisting of an integrated electricity, water, and transportation system. Such a graph has the potential for dynamic modeling, resilience analysis, and integrated decision-making.