On the use of random graphs in analysing resource utilization in urban systems

Abstract

Urban resource models increasingly rely on implicit network formulations. Resource consumption behaviours documented in the existing empirical studies are ultimately by-products of the network abstractions underlying these models. Here, we present an analytical formulation and examination of a generic demand-driven network model that accounts for the effectiveness of resource utilization and its implications for policy levers in addressing resource management in cities. We establish simple limiting boundaries to systems' resource effectiveness. These limits are found not to be a function of system size and to be simply determined by the system's average ability to maintain resource quality through its transformation processes. We also show that resource utilization in itself does not enjoy considerable size efficiencies with larger and more diverse systems only offering increased chances of finding matching demand and supply between existing sectors in the system. Thermodynamically speaking, the rate of utilization of resources in cities is then subject to the quality of the imported resources, i.e. their exergetic content, as well as the efficiency of such systems in extracting the exergetic content in their processes [2].As cities grow in size and complexity, self-organizational behaviours that are typical of open thermodynamic systems emerge. These include diversifying intra-system interactions and increasing their intensity in order to more effectively process the increased energy intake [3]. Such behaviours provide the capacity for growth and expansion prompting cities to seek and destroy more exergetic content. Given the limited nature of resource supplies, this is typically better achieved by prolonging the chain of transformation processes within systems, i.e. keeping materials in systems for longer, which in turn increases their capacity in retaining and circulating quality resources through these longer chains [4,5]. For complex dissipative thermodynamic systems like cities, measuring this gradient of exergy destruction in the overall system serves as a performance indicator of the systems' capability to use resources they import and re-circulate [6]. This very quality is echoed in and underpins the working principles of circular economy where reduce, maintain, re-use, refurbish and recycle are incorporated to address the overextraction of resources through maximizing transformation efficiencies (reduce), keeping resource in use (maintain) and prolonging next-use chains (re-use, refurbish and recycle) through various strategies. Applying circular-economic principles not only relieves the demand on resource use, but also promotes system adaptations and product design for cutting waste and carbon emissions [7]. The essence of the circular economy is to retain the usefulness of resources through a hierarchy of strategies where higher levels of resource management such as maintenance to extend the current life are preferred, with reuse for a second life, and then repair and remanufacturing further down the ...

Does New Urbanization Promote Urban Metabolic Efficiency?

“…This paper finds that NU not only promotes local UME but also promotes the UME of neighboring areas through the spatial spillover effect, which enriches the academic knowledge on the environmental protection effect of NU, and echoes the research viewpoints of Lin and Zhu (2021) [109]. The reason for this is that NU is urbanization with urban-rural integration, industrial interaction, conservation and intensification, ecological livability, and harmonious development as its basic features and therefore is conducive to enhancing the capacity of urban environmental regulation [110,111], promoting the green transformation of industries [112], improving the capacity of urban resource utilization [113,114], and optimizing the spatial structure of the city [115], which in turn reduces the input resources for urban operation, enhances the performance outputs of urban operation, and ultimately improves the UME [116]. At the same time, the findings of this study provide China's answer to the real-life dilemma of "how to urbanize with the goal of sustainable urban development in mind", which is faced by many countries [117][118][119], and will help countries and alliances such as the Caribbean region [120], UNESCO biosphere reserves [121], Singapore [16], India [122], and Australia [123] to better address sustainable development in the process of urbanization.…”

Resource Effectiveness in and Across Urban Systems

“…In the majority of model formulations, these processes and their efficiencies are characteristics of the node inside which they take place. 52,53 Figure 1 shows a schematic representation of such network arrangements. Figure 1.…”

“…Figure 1. Schematic showing a node pair and the resource flow between them broken down in exergetic terms to its utilized, wasted, and exported componentsadapted from Arbabi et al 52 Expanding this formulation across all nodes and edges would give the system-wise overall resources balance as…”

A scalable data collection, characterization, and accounting framework for urban material stocks

“…The implementation of a circular economy faces a number of challenges industry wide, including a limited awareness across the supply chain (Adams et al., 2017), concerns about the consistency of flows of returned goods, and an unclear market demand for secondary resources (Guldmann & Huulgaard, 2020). Overcoming such barriers requires highly detailed modeling of building stocks so that stakeholders throughout the supply chain can obtain the exact quantity and quality of secondary resources, for example, construction bricks or panes of glass, that would be recoverable from a specific building nearing demolition (Arbabi et al., 2020). To enable this, estimates of material quantity and quality need to be spatially explicit and be measured at a building level.…”