| 2. |
- Montazeri, Amir, et al.
(author)
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A spatial land use clustering framework for investigating the role of land use in mediating the effect of meteorology on urban air quality
- 2021
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In: Atmospheric Environment: X. - : Elsevier. - 2590-1621. ; 12
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Journal article (peer-reviewed)abstract
- Air pollution in urban areas is driven by emission sources and modulated by local meteorology, including the effects of urban form on wind speed and ventilation, and thus varies markedly in space and time. Recently, mobile measurement campaigns have been conducted in urban areas to measure the spatial distribution of air pollutant concentrations. While the main focus of these studies has been revealing spatial patterns in mean (or median) concentrations, they have mostly ignored the temporal aspects of air pollution. However, assessing the temporal variability of air pollution is essential in understanding the integrated exposure of individuals to pollutants above critical thresholds. Here, we examine the role of urban land use in mediating the effect of regional meteorology on Nitrogen Dioxide (NO2) concentrations measured in different regions of Oakland, CA. Inspired by Land Use Regression (LUR) models, we cluster 30-m road segments in the urban area based on their land use. The concentration data from the resulting clusters are stratified based on seasonality and conditionally averaged based on concurrent wind speeds. The clustering analysis yielded 7 clusters, with 4 of them chosen for further statistical analysis due to their large sample sizes. Two of the four clusters demonstrated in winter a strong negative linear relationship between NO2 concentration and wind speed (R-2 > 0.87) with a slope of approximately 3 ppb/m s(-1). A weaker correlation and flatter slope was found for the cluster representing road segments belonging to interstate highways (R-2 > 0.73 and slope < 2 ppb/m s(-1)). No significant relationship was found during the summer season. These findings are consistent with the concept of strong vertical mixing due to highway traffic and increased surface heat fluxes during summer weakening the relationship between wind speed and NO2 concentrations. In summary, the clustering analysis framework presented here provides a novel tool for use with large-scale mobile measurements to reveal the effect of urban land form on the temporal dynamics of pollutant concentrations and ultimately human exposure.
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| 3. |
- Nikbakht, Mehran Vahedi, et al.
(author)
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Identification and Ranking of Factors Affecting the Delay Risk of High-Rise Construction Projects Using AHP and VIKOR Methods
- 2024
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In: INFRASTRUCTURES. - : MDPI. - 2412-3811. ; 9:2
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Journal article (peer-reviewed)abstract
- Construction projects, especially those for commercial purposes, require thorough planning and control to ensure success within predetermined budgets and timelines. This research, conducted in Mashhad, Iran, employs the analytic hierarchy process (AHP) and VIKOR methods to identify and rank factors influencing delays in high-rise projects. The study, based on a sample of 40 projects, emphasizes the comprehensive nature of our research method. The scale for features in project selection includes societal importance (with different applications including cultural hubs, affordable housing initiatives, and urban renewal for social equity), size (less and more than 20 units in residential projects), and diversity (mixed-use development, inclusive infrastructure, and cultural and recreational spaces), contributing to a comprehensive analysis of construction delays. Expert project managers and engineers provided insights through two questionnaires, and their responses underwent thorough analysis. Our findings not only underscore the significance of factors contributing to project success but also rank their impact on the likelihood of delays. The study reveals that the negative effects of these factors on cost, time, and project quality vary. Time emerges as the most influential parameter, with approximately six times more impact on cost and nine times more on quality. Contractor financial weakness, delays in allocating financial and credit resources, insufficient project resource allocation, contractor technical and executive weakness, and a lack of proper implementation and project control are identified as the most important factors contributing to delays.
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