1,721,004 research outputs found
Network Centrality of Metro Systems
Full text linkWhilst being hailed as the remedy to the world’s ills, cities will need to adapt in the 21st century. In particular, the role of public transport is likely to increase significantly, and new methods and technics to better plan transit systems are in dire need. This paper examines one fundamental aspect of transit: network centrality. By applying the notion of betweenness centrality to 28 worldwide metro systems, the main goal of this paper is to study the emergence of global trends in the evolution of centrality with network size and examine several individual systems in more detail. Betweenness was notably found to consistently become more evenly distributed with size (i.e. no “winner takes all”) unlike other complex network properties. Two distinct regimes were also observed that are representative of their structure. Moreover, the share of betweenness was found to decrease in a power law with size (with exponent 1 for the average node), but the share of most central nodes decreases much slower than least central nodes (0.87 vs. 2.48). Finally the betweenness of individual stations in several systems were examined, which can be useful to locate stations where passengers can be redistributed to relieve pressure from overcrowded stations. Overall, this study offers significant insights that can help planners in their task to design the systems of tomorrow, and similar undertakings can easily be imagined to other urban infrastructure systems (e.g., electricity grid, water/wastewater system, etc.) to develop more sustainable cities
Book Review: Triumph of the City, Edward Glaeser
Full text linkJTLU vol. 6, no.3, pp. 87-89 (2013)The authors review the book Triumph of the City by Edward Glaeser (Penguin Press, 2011).Good, Max; Derrible, Sybil. (2013). Book Review: Triumph of the City, Edward Glaeser. Retrieved from the University Digital Conservancy, 10.5198/jtlu.v6i3.466
Exploring machine learning models to predict atmospheric water harvesting with an ion deposition membrane
Full text linkThis work investigates the performance of a novel membrane-based atmospheric water harvesting (AWH) unit under various operating conditions of ambient temperature, relative humidity (RH), and carrier fluid flow rate. Ion deposition membranes (IDMs) were selected for their ability to enhance water uptake by lowering the water vapor saturation pressure at the gas-membrane interface. This effect, achieved through metal ion implantation into PTFE-based membranes, improves water harvesting rates – especially under low RH conditions – by up to a factor of four compared to untreated membranes. The benchmark design was tested over all possible combinations of four distinct carrier fluid flow rates, three temperatures, and six RH values. The yield with a lab-scale prototype was as high as 354 ml/day of water, with an average of 155 ml/day, corresponding to water harvesting rates of 22.13 kg/m2/day and 9.69 kg/m2/day, respectively. The experimental dataset obtained was used to build three machine learning (ML) regression models to predict the amount of water harvested under specific operating conditions. The ML techniques are: Support Vector Regression, Gradient Boosting Regression, and Multilayer Perceptron. These methods achieved accuracy scores as high as 89 %, proving suitable for implementation in the regulation of AWH plants featuring this technology. The best-performing model (Multilayer Perceptron) was used to predict the water harvesting potential on a typical spring day in Jeddah, Saudi Arabia, a region facing severe water scarcity
Data and Python script for article "A text mining analysis of the climate change literature in industrial ecology'
No full textThe data and Python script are part of the forum article "A text mining analysis of the climate change literature in industrial ecology" authored by Dayeen, F.R., Sharma, A.S., and Derrible, S., and published in the Journal of Industrial Ecology in 2020.
The Python script and instructions are included in the LiTCoF_v1.00-py.zip file. The original data is available in two formats: .csv and .pkl.
Updates of the script will be posted at https://github.com/csunlab/LiTCoF and at https://csun.uic.edu/codes/LiTCoF.html. The data is also available at https://csun.uic.edu/datasets.html#AbstractsIE.
Feel free to contact any of the authors for information and questions about the data and code.</p
Special issue on “Reliability and resilience of emerging mobility systems”, an editorial note
No full textThis Editorial Note accompanies the special issue devoted to the development of new concepts, theories and methods that address reliability and resilience related to the planning, dynamic operation, and level of service of novel mobility systems. This special issue on ‘Reliability and Resilience of Emerging Mobility Systems’ consists of seven papers which are dedicated to methodological and theoretical developments as well as advanced applications in this domain. Several of the contributions originated from works presented at INSTR2021 (the 8th International Symposium on Transport Network Reliability). In this Editorial note we reflect on the contributions made in each of the articles included in this special issue.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport and Plannin
The Properties and Effects of Metro Network Designs
No full textSince 2008, more than half of the world population lives in cities. To cope with this rapid urbanization in a sustainable manner, transit systems all around the world are likely to grow. By studying 33 networks in the world, this thesis identifies the properties and effects of metro network designs by using a graph theory approach.
After the literature review, a new methodology was introduced to translate networks into graphs; it notably accounts for various transit specificities (e.g., presence of lines). Metro networks were then characterised according to their State, Form, and Structure; where State relates to the development phase of metros; Form investigates the link between metros and the built environment; Structure examines the intrinsic properties of metros, by notably looking at their connectivity. Subsequently, the complexity and robustness of metros were studied; metros were found to possess scale-free and small-world features although showing atypical topologies; robustness emphasizes on the presence of alternative paths. Three network design indicators (coverage, directness and connectivity) were then related to ridership (annual boardings per capita), and positive relations were observed, which suggests that network design plays an important role in their success. Finally, these concepts were applied to the Toronto metro plans announced by the Toronto regional transportation authority, Metrolinx; it was found that the grid-pattern nature of the plans could hinder the success of the metro; seven possible improvements were suggested.
Overall, the topology of metro networks can play a key role in their success. The concepts presented here can particularly be useful to transit planners; they should also be used along with conventional planning techniques. New transit projects could benefit greatly from an analysis of their network designs, which in turn may play a relevant role in the global endeavour for sustainability.Ph
The Properties and Effects of Metro Network Designs
Full text linkSince 2008, more than half of the world population lives in cities. To cope with this rapid urbanization in a sustainable manner, transit systems all around the world are likely to grow. By studying 33 networks in the world, this thesis identifies the properties and effects of metro network designs by using a graph theory approach.
After the literature review, a new methodology was introduced to translate networks into graphs; it notably accounts for various transit specificities (e.g., presence of lines). Metro networks were then characterised according to their State, Form, and Structure; where State relates to the development phase of metros; Form investigates the link between metros and the built environment; Structure examines the intrinsic properties of metros, by notably looking at their connectivity. Subsequently, the complexity and robustness of metros were studied; metros were found to possess scale-free and small-world features although showing atypical topologies; robustness emphasizes on the presence of alternative paths. Three network design indicators (coverage, directness and connectivity) were then related to ridership (annual boardings per capita), and positive relations were observed, which suggests that network design plays an important role in their success. Finally, these concepts were applied to the Toronto metro plans announced by the Toronto regional transportation authority, Metrolinx; it was found that the grid-pattern nature of the plans could hinder the success of the metro; seven possible improvements were suggested.
Overall, the topology of metro networks can play a key role in their success. The concepts presented here can particularly be useful to transit planners; they should also be used along with conventional planning techniques. New transit projects could benefit greatly from an analysis of their network designs, which in turn may play a relevant role in the global endeavour for sustainability.Ph
Characterizing Metro Networks: State, Form, and Structure
No full textThis paper seeks to characterize the network feature of metro systems by adapting various concepts of graph theory to define three characteristics of transit networks: state, form and structure. State measures the complexity of a network. Form investigates the link between metro systems and the built environment, distinguishing networks oriented towards regional accessibility, local coverage or regional coverage. Structure examines the intrinsic properties of current networks. The three characteristics are also linked to transit line type and land-use. The method presented is this paper is particularly useful at the strategic planning phase as it offers information on current and planned systems, which can then be used towards setting a vision, defining new targets and making decision between various scenarios. It can also be used to compare existing systems and identify paths of development
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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