Model Of Urban System Research Articles

The simple urban radiation model for estimating mean radiant temperature in idealised street canyons

Thermal comfort is an important component of health-related urban well-being (UrbWellth) of the urban population. Outdoors in sunny conditions the human thermal environment is strongly influenced by radiation fluxes, which are often expressed as a mean radiant temperature (Tmrt). In an urban environment Tmrt is, especially in sunny conditions, strongly influenced by the building morphology due to shading and reflection of radiation. To model these morphological effects within an urban system model for UrbWellth, a simple model for Tmrt is required that simplifies the actual urban environment to reduce computational costs but still considers the most important aspects of Tmrt variability within a city. To do so, within this paper the open-source and modular Simple Urban Radiation Model (SURM) is presented. SURM is validated with respect to different calculation methods of both view factors and radiative fluxes as well as to radiation modification by buildings. The results indicate that SURM models radiative fluxes and radiative influences of buildings sufficiently accurate to be applicable as one component of an urban system model for sunny conditions.

A review of the use of geosocial media data in agent-based models for studying urban systems

ABSTRACT Since the rapid growth of urban populations, the study of urban systems has gained considerable attention from researchers, decision makers, governments, and organizations. Urban systems are complex and dynamic such that they produce emergent patterns such as self-organization and nonlinearity. Agent-based modelling presents an approach to simulating and abstracting urban systems to reveal and study emergent patterns from urban-related entities. However, agent-based models are difficult to effectively optimize and validate without high quality real-world data. Geosocial media data provides agent-based models with location-enabled data at high volumes and frequencies. Integrating agent-based models with geosocial media data presents opportunities in advancing and developing studies in urban systems. This paper provides a general overview of concepts, review of recent applications, and discussion of challenges and opportunities in the context of using geosocial media data in agent-based models for urban systems. We argue that ABMs focused on studying urban systems can benefit greatly from geosocial media data, given that research moves towards standard guidelines that enable the comparison and effective use of ABMs, and geosocial media data under appropriate circumstances and applications.

A multi-source virtual water metabolism model for urban systems

Increasing industrialization and urbanization stress on water resources in the world. It is crucial to analyze urban virtual water metabolism systems comprehensively to uncover economic water flow reduction pathways to support maintainable development. In this study, a multi-source virtual water metabolism (MVWM) model is developed for Chongqing City to facilitate distributive analysis of the interactive effects from multiple water sources on urban systems. In addition, three disaggregated types of water sources (surface water, groundwater, and other water) are examined with their distributive features in relation to virtual and physical water shortages being highlighted among multiple sectorial users. The system’s health condition is monitored by integrating ecological network analysis (ENA) and input-output analysis (IOA). Results illustrate that the groundwater system in Chongqing is relatively healthy and can be exploited appropriately, while the surface water system has higher water stress. Direct water consumptions are mostly happened in primary industries, while indirect water consumptions are most likely to occur in secondary and tertiary industries. Based on ecological hierarchy analysis, Advanced Manufacturing (AM) has large pulling and driving force simultaneously, which denotes that AM is very important for the whole economic system of Chongqing. Besides, some typical industries with damaging relationships are identified based on ecological network utility analysis to alleviate water scarcity, such as construction, mining and washing of coal, as well as manufacture of foods and processing of tobacco.

КОНЦЕПТУАЛЬНА ФІНАНСОВО-ЕКОНОМІЧНА МОДЕЛЬ УРБАНІЗОВАНИХ СИСТЕМ

The dynamic processes of urbanization and administrative reform in Ukraine are challenged by a range of problems and tasks to improve the public urban policy, including the reforming and development of public transport systems, greening and humanization of environment, and improvement of conditions and living standards of residents. The problem of forming the cities’ financial foundation and efficient links between the cities and surroundings, as well as achievement of financial and economic effects from their consolidation into joint socio-economic and spatial structures is one of the most urgent to be solved. The paper aims to substantiate the conceptual financial model of urban systems that takes into account the new conditions and trends in the development of the cities in Ukraine that are related to the intensification of agglomeration processes. It will contribute to efficient cooperation between communities to solve complex tasks of spatial and socio-economic development and to disclose the cities’ opportunities to form budget policy in conditions of agglomerations. The paper contemplates the possibilities to form the financial-economic model at various territorial levels. The author develops the structural model of an urban system with a city as the core of the urban system, which is the administrative-territorial unit with defined boundaries, specific territorial development with prevailing spots of non-agricultural functions, capital concentration, economic activity types, economic and social benefits, and residents employed in non-agricultural production, institutions, and organizations. The legal framework is analyzed, contributing to the substantiation of financial-economic models at the level of cities, urban agglomerations, and urban systems. The financial-economic model of a city and consolidated territorial communities is built. The perspectives of urban systems’ development are outlined, and opportunities to search for efficient mechanisms of local budget forming through cooperation between territorial communities to solve the problems of the socio-economic and spatial development of territories are substantiated. REFERENCES1. Derzhavne upravlinnia statystyky. URL: http://ukrstat.gov.ua [in Ukrainian].2. Demin N.M., Timchuk N.F. Metod opredelenija zon vlijanija gorodov. Rajonnaja planirovka i rasselenie (v pomoshh’ proektirovshhiku-gradostroitelju). Kiev: Budivel’nik, 1972. Iss. I. P. 23-28 [in Russian].3. Habrel M.M. Prostorova orhanizatsiia mistobudivnykh system. Kyiv: Vydavnychyi dim A.С.С., 2004. 400 p. [in Ukrainian].4. Vozniak H.V. Biudzhetna polityka rozvytku rehioniv Ukrainy: suchasna paradyhma ta oriientyry podalshykh reform. DU Instytut rehionalnykh doslidzhen imeni M.I. Dolishnoho NAN Ukrainy. Lviv, 2016. 520 p. [in Ukrainian].5. Palekha Yu.M. Ekonomiko-heohrafichni aspekty formuvannia vartosti terytorii naselenykh punktiv. Kyiv: Profi, 2006. 324 p. [in Ukrainian].

Modified Maintenance Network Model for Urban Rail Transit Systems Based on the Variable Coverage Radius: Evidence from Changchun City in China

Network-wide maintenance lacks strong theoretical support and practical cases. However, research on this topic has entered an extensive exploratory stage; for example, new network design methods are being sought, and successful practices from traditional maintenance by line and by profession are being incorporated. This paper proposes a novel set-covering model with the variable coverage radius for the maintenance network of urban rail transit systems in the context of network-wide maintenance. The concepts of network-wide maintenance follow principles that are similar to those of bio-geography-based optimization (BBO), i.e., patterns of migration, variation, and extinction of different populations in different habitats. Therefore, a BBO algorithm is implemented with combinatorial optimization programming. Experiments from Changchun city in China show that the proposed model and algorithm are effective in fulfilling network-wide requirements through a direct tradeoff between the coverage radius and maintenance response time. In addition, the maintenance capacity and variable coverage radius of each maintenance point influence both the maintenance timeliness and resource utilization of maintenance units.

Empowering Urban Governance through Urban Science: Multi-Scale Dynamics of Urban Systems Worldwide

Cities are facing many sustainability issues in the context of the current global interdependency characterized by an economic uncertainty coupled to climate changes, which challenge their local policies aiming to better conciliate reasonable growth with livable urban environment. The urban dynamic models developed by the so-called “urban science” can provide a useful foundation for more sustainable urban policies. It implies that their proposals have been validated by correct observations of the diversity of situations in the world. However, international comparisons of the evolution of cities often produce unclear results because national territorial frameworks are not always in strict correspondence with the dynamics of urban systems. We propose to provide various compositions of systems of cities in order to better take into account the dynamic networking of cities that go beyond regional and national territorial boundaries. Different models conceived for explaining city size and urban growth distributions enable the establishing of a correspondence between urban trajectories when observed at the level of cities and systems of cities. We test the validity and representativeness of several dynamic models of complex urban systems and their variations across regions of the world, at the macroscopic scale of systems of cities. The originality of the approach resides in the way it considers spatial interaction and evolutionary path dependence as major features in the general behavior of urban entities. The models studied include diverse and complementary processes, such as economic exchanges, diffusion of innovations, and physical network flows. Complex systems dynamics is in principle unpredictable, but contextualizing it regarding demographic, income, and resource components may help in minimizing the forecasting errors. We use, among others, a new unique source correlating population and built-up footprint at world scale: the Global Human Settlement built-up areas (GHS-BU). Following the methodology and results already obtained in the European GeoDiverCity project, including USA, Europe, and BRICS countries, we complete them with this new dataset at world scale and different models. This research helps in further empirical testing of the hypotheses of the evolutionary theory of urban systems and partially revising them. We also suggest research directions towards the coupling of these models into a multi-scale model of urban growth.

Modeling Soil Moisture Redistribution and Infiltration Dynamics in Urban Drainage Systems

Hydrological modeling has become a common approach for the design of stormwater management strategies which, at the same time, increasingly rely on permeable and decentralized systems to mitigate the impacts of urbanization. In most applications, little attention is however paid to the temporal variability of infiltration fluxes resulting from soil moisture redistribution between rain events. In this study, a conceptual infiltration-redistribution model is introduced to investigate the importance of the description of infiltration fluxes for the modeling of sustainable urban drainage systems (SUDS). Model verification against numerical solution of Richards equation is first conducted. Performance indicators simulated with the model for a large range of infiltration scenarios are later compared to those obtained with simpler approaches, commonly used in urban hydrology. The model is shown to replicate at a low computational cost numerical solutions of Richards equation. Regarding SUDS modeling, results indicate that a correct description of the temporal variability of infiltration fluxes (1) may be needed for some configurations to assess long-term volume-reduction efficiencies and (2) is more generally required when examining frequency-based performance indicators.

An Assessment Method for Traffic State Vulnerability Based on a Cloud Model for Urban Road Network Traffic Systems

Directed against the shortcoming of the vulnerability assessment based on complex network theory for urban road network traffic systems, a state vulnerability assessment method, considering the influence of congestion, is constructed by using a cloud model to describe the randomness and uncertainty characteristics of risks. First, based on complex network theory, the primary index assessment system of road network vulnerability is introduced. Second, to describe the congestion states of roads, the cloud model theory is introduced to characterize the congestion features of road sections. After that, a state vulnerability identification method based on congestion cloud charts is constructed. Finally, on the basis of topological mapping of road network in Nan’an District in Chongqing, experiments and analyses are carried out in light of the actual congestion delay index dataset provided by AutoNavi Maps to verify the effectiveness and rationality of our proposed scheme. The experimental results show that the assessment method of state vulnerability can better describe the overall operational state and vulnerable road sections for road network.

About passenger travels demand modeling in urban transportation systems

In this paper, the basic concepts of modeling of urban transport systems are analyzed. The known variants of the definition of the concept of the transport system, its main components and the essence of the stages of identification of transport systems (TS) are presented. The example of the Lviv city TS shows the process of modeling the transport network, determining the time characteristics of the modeled transport system and forming a demand matrix for trips of a certain type in a certain segment of users (origin-destination matrix when moving students from their places of compact residence to the nodes of external transport for further implementation of intercity travel). The obtained indicators can be further applied in determining the demand for transportation in transport systems of large cities.

A Collaborative Approach for an Integrated Modeling of Urban Air Transportation Systems

The current push in automation, communication, and electrical energy storage technologies has the potential to lift urban mobility into the sky. As several urban air mobility (UAM) concepts are conceivable, all relevant physical effects as well as mutual interrelations of the UAM system have to be addressed and evaluated at a sufficient level of fidelity before implementation. Therefore, a collaborative system of systems modeling approach for UAM is presented. To quickly identify physical effects and cross-disciplinary influences of UAM, a pool of low-fidelity physical analysis components is developed and integrated into the Remote Component Environment (RCE) workflow engine. This includes, i. a., the disciplines of demand forecast, trajectory, vertiport, and cost modeling as well as air traffic flow and capacity management. The definition and clarification of technical interfaces require intensive cooperation between specialists with different areas of expertise. To reduce this communication effort, the Common Parametric Aircraft Configuration Schema (CPACS) is adapted and used as central data exchange format. The UAM system module is initially applied for a 24-hour simulation of three generic networks in Hamburg City. After understanding the basic system-level behavior, higher level analysis components and feedback loops must be integrated in the UAM system module for evaluation and optimization of explicit operating concepts.

Capturing the long-term interdependencies between building thermal energy supply and demand in urban planning strategies

Urban areas play a crucial role in fostering low carbon energy patterns and the decarbonization of buildings energy consumption is at the heart of this process. Energy system analyses have recently gained the attention of urban policy makers due to their comprehensive and long-term perspective on the activities of the entire supply/demand chain, traditionally treated independently when shaping building urban energy strategies.This paper presents a spatial and temporally resolved urban energy system optimization model with specific features in order to describe the interactions between energy efficiency in buildings and heat supply strategies. A preliminary case study is proposed for offering numerical evidence to results. The results show that a planned combination of fuel switching, energy efficiency and building retrofit may complementary lead to meet ambitious climate targets at a reasonable added cost.From the results emerge that urban energy system models might help researcher and decision makers in generating robust holistic scenarios and in providing quantitative elements to exclude actions that are not economically affordable, technologically feasible and environmentally sustainable. Nevertheless, to be fully adoptable for real applications, existing barriers need to be overcome with special attention to the definition of input data protocols and the stakeholder involvement since the beginning.

Advances in Urban Meteorological Research in China

Over the past decades, a large number of studies have been carried out in the field of urban meteorology in China. This paper summarizes the main progress in urban meteorology research from four aspects: urban meteorological observation network and field campaign, multi-scale model of urban meteorology, interaction between urban meteorology and atmospheric environment, and the impacts of urbanization on weather and climate. Major advances are as follows. China’s major cities have established or are improving comprehensive urban meteorological observation networks characterized by multi-platform, multi-variable, multi-scale, multi-link, and multi-function. Beijing, Nanjing, Shanghai, and other cities carried out urban meteorological field campaigns, which were included in the WMO research demonstration project. Wind tunnel experiments and scale-model outdoor experiments were successfully conducted. Multi-scale urban meteorological and air quality prediction numerical model systems have been developed and put into operational use. The urban heat island effect; urban impacts on precipitation, regional climate, and air quality; urban planning; and interaction between urban meteorology and atmospheric environment are extensively investigated. Finally, efforts to improve observational technology, data assimilation, and urban system modeling, to explore the impacts of urbanization on environment and human health, and to provide integrated urban hydro-meteorological climate and environmental services are planned ahead.

The Concept of a Sustainable Urban Transport System Model for Developing Countries on the Example of Lagos

Abstract The subject of the article is the concept of a sustainable urban transport system model for developing countries on the example of Lagos in Nigeria. The city of Lagos is the largest and most populated city in Africa. Nowadays, the state of Lagos is facing many challenges, and the problem of urban transport is becoming more and more important due to the increase in the number of inhabitants and the size of the city. Significant problems were identified in the urban transport system in the Lagos state, and conceptual solutions were proposed taking into account the approach of sustainable development.

Event selection and two-stage approach for calibrating models of green urban drainage systems

Abstract. The calibration of urban drainage models is typically performed based on a limited number of observed rainfall–runoff events, which may be selected from a larger dataset in different ways. In this study, 14 single- and two-stage strategies for selecting the calibration events were tested in calibration of a high- and low-resolution Storm Water Management Model (SWMM) of a predominantly green urban area. The two-stage strategies used events with runoff only from impervious areas to calibrate the associated parameters, prior to using larger events to calibrate the parameters relating to green areas. Even though all 14 strategies resulted in successful model calibration (Nash–Sutcliffe efficiency; NSE >0.5), the difference between the best and worst strategies reached 0.2 in the NSE, and the calibrated parameter values notably varied. The various calibration strategies satisfactorily predicted 7 to 13 out of 19 validation events. The two-stage strategies reproduced more validation events poorly (NSE <0) than the single-stage strategies, but they also reproduced more events well (NSE >0.5) and performed better than the single-stage strategies in terms of total runoff volume and peak flow rates, particularly when using a low spatial model resolution. The results show that various strategies for selecting calibration events may lead in some cases to different results in the validation phase and that calibrating impervious and green-area parameters in two separate steps in two-stage strategies may increase the effectiveness of model calibration and validation by reducing the computational demand in the calibration phase and improving model performance in the validation phase.

Spatially-resolved urban energy systems model to study decarbonisation pathways for energy services in cities

This work presents the COMET (Cities Optimisation Model for Energy Technologies) model, a spatially-resolved urban energy systems model that takes into account energy service demands for heating, cooling, electricity, and transport, and finds cost-effective pathways for supplying these demands under carbon constraints, trading-off energy supply, network infrastructure, and end-use technologies. Spatially-resolved energy service demands were obtained for the city of Sao Paulo, and six scenarios were modelled. Results show that district cooling is cost-effective in the highest linear cooling density zones, with full penetration in zones with over 1100 kWh/m by 2050. This threshold diminishes with tighter carbon constraints. Heating is electrified in all scenarios, with electric boilers and air-source heat pumps being the main supply technologies for the domestic and commercial sectors respectively by 2050. In the most carbon constrained scenario with a medium decarbonised electricity grid, ground source heat pumps and hydrogen boilers appear as transition technologies between 2030 and 2045 for the commercial and domestic sectors respectively, reaching 95% and 40% of each sector’s heat installed capacity in 2030. In the transport sector, ethanol cars replace gasoline, diesel, and compressed natural gas cars; compressed natural gas buses replace diesel and electric buses; and lorries continue using diesel. In carbon constrained scenarios, higher penetrations of electric cars and buses are obtained, while no change is observed for lorries. Finally, the most expensive scenario was only 6% more expensive than the reference scenario, meaning that achieving decarbonisation targets is not much costlier when comparing scenarios from a system-wide perspective.

Design of Renewable and System-Beneficial District Heating Systems Using a Dynamic Emission Factor for Grid-Sourced Electricity

In future energy scenarios with a high share of renewable energies within the electricity system, power-to-heat technologies could play a crucial role for achieving the climate goals in the heating sector. District heating systems can integrate volatile wind and photovoltaic energy sources and resolve congestions within the electricity grid, leading to curtailment of renewable electricity generation. This paper presents a design approach for setting up system-beneficial power-to-heat-based district energy systems. Within the scope of the project QUARREE100 an existing district in the provincial town Heide in Northern Germany is examined. A linear investment and unit commitment optimization model is applied. By considering local dynamic emission factors for grid-sourced electricity, which contain information on local wind energy curtailment as well as the emission intensity of the overall electricity generation, a renewable and system-beneficial design can be derived. With this method, the minimal rated power and capacity of energy converter and storage units can be determined to achieve emission reductions with respect to minimum costs. The approach of using different methods for the consideration of the emissions of grid-sourced electricity is analyzed based on different scenarios. By using a dynamic emission factor for grid-sourced electricity, lower emissions with fewer costs can be achieved. It is shown that a dynamic assessment leads to different design decisions and far-reaching deviations in the unit commitment. The results clearly show that a constant emission factor is no longer an option for grid-sourced electricity in urban energy system models.

Utilization of a pond in East Jakarta for a sustainable urban drainage system model

High population growth in the area of East Jakarta has led to more construction of settlements, including in several areas of East Jakarta, which includes Jalan Pengantin Ali in Ciracas Sub-District. When very heavy rains fall in the rainy season, this place is often flooded, while in the dry season there is a scarcity of raw water or clean water. This study examines the application of sustainable drainage systems with the technique of making a retention pond as a flood control alternative. The purpose is to hold water runoff during the rainy season so that it does not enter the river directly, and so that some of the collected water could be used to meet the clean water supply needs of the people. The calculation of rainwater potential used the height of the monthly average rainfall. The retention pond capacity was determined by the pool simulation method during the rainy season. The planned flood discharge was calculated using the Nakayasu HSS method. The obtained results indicated a peak discharge value with a return period of 2 years that amounted to 8.84 m3/sec. The planned retention pond area is 6380.94 m2, with a retention pond height of 4 m, a dike slope of 1:1, and the elevation of the overflow base being at an altitude of 38.5 meters above sea level (masl). From the results of the HEC-RAS 5.0.6 software, an optimal overflow width of 2 m was obtained, with an outflow discharge of 4.55 m3/sec and a pond volume of 19530 m3. With the retention pond, flood peak discharge could be reduced by 4.29 m3/sec. This will allow the flood discharge in the rainy season to be reduced and increased clean water needs in the dry season to be met.

On the consistency of urban cellular automata models based on hexagonal and square cells

Cellular automata have found extensive applications in the modelling of urban systems. Calculations in cellular automata models are based on cell centroids and therefore cellular automata models are sensitive to the choices of cell size and shape. While the effect of cell size for urban simulation has been studied, discussions on the effect of cell shape on urban cellular automata models have been limited. Applications in other fields suggest there are advantages of using hexagonal cells over square cells, yet most urban cellular automata models use square cells. Using connectivity indices from graph theory, experiments in this study compared models based on hexagonal and square cells to examine the potential advantage of hexagonal cells in urban cellular automata models. This paper finds that simulation results from the model with hexagonal cells are more consistent and concludes that hexagonal cells would increase the robustness of model simulation.

Agent-based Model for Simulating Urban System

In this paper, we address the issue related to the modelling and simulation of urban systems. We propose a new approach for simulating urban system based on multi-agent paradigm. Our proposed model is based on the use of a coupling between cellular agents and vector agents. These agents made it possible to take into account the spatial dimension of urban systems as well as the modelling of all the rules that govern them. To allow reusability of our model, we apply the VOYELLE approach by defining an environment model, an organization model, an agent model and an interaction model. We test our proposed model with a case study on Casablanca city. We discuss the problem of urbanization of Casablanca by following an approach that reduces the problem into two sub-problems similar but are treated differently: first, predict the city’s need of housing (individual housing zone, multifamily housing zone, ...) and then anticipate the city’s need of public services and ensure better spatial distribution of these equipment to best serve the people needs. Then we did experimentation with two simulation scenarios by changing in each scenario the hypotheses concerning urban planning especially in terms of demographic growth rate and residential sprawl.

Reliability Modeling and Evaluation of Urban Multi-Energy Systems: A Review of the State of the Art and Future Challenges

Urban multi-energy systems (UMESs) are integrated energy systems (IESs) which can alleviate the current energy crisis, improve energy utilization and realize multi-energy complementarity of modern. Various subsystems involved in the coupling of UMESs, including power grids, gas pipeline networks, cold/heat networks, transportation networks, and energy cyber-physical system, exhibit coupling characteristics such as multi-energy source modeling, complex uncertainty factor modeling, mutual influence of information and physical coupling. At present, the modeling and reliability assessments of UMESs are the most urgent tasks. In this paper, the latest research results on the reliability modeling and evaluation of UMESs are analyzed by considering their coupling components. In addition, the reliability modeling methods and the evaluation indexes of UMESs, including power-gas systems, power-thermal systems, power-traffic systems, and energy cyber-physical systems, are presented in this paper, with specific UMES modeling methods divided into model-driven modeling and data-driven modeling. Finally, future challenges for the reliability modeling and evaluation of UMESs are proposed, such as the dispatch strategy of the coupling components needs to be developed and continuously optimized to improve the reliability of UMESs, and the resilience of UMESs under the extreme scenarios needs to be further studied.