1,721,066 research outputs found
CFD modelling: The most useful tool for developing mesoscale urban canopy parameterizations
No full textSensitivity analysis of urban microclimatic conditions and building energy consumption on urban parameters by means of idealized numerical simulations
No full textIn the present work the mesoscale meteorological model Weather Research and Forecasting (WRF), coupled with a multilayer urban canopy parameterization and a building energy model (BEP + BEM), is used to analyze the sensitivity of both urban climatic conditions and building energy consumption on parameters characterizing urban materials and the building environment. In particular, simulations in an idealized urban area, with different urban geometry and under different climatic conditions, are compared to evaluate the relative importance of various parameters. Results highlight that the target indoor temperature has the strongest impact on both building energy consumption and external air temperature. Building energy consumption is also significantly affected by other internal building parameters, such as the ventilation rate and the heat produced by equipment and occupants. On the contrary, no significant influence, either on building energy consumption or on air temperature, is found from changes in wall albedo and emissivity
Modelling the urban boundary-layer over a typical mediterranean city using WRF: Assessment of UHI and thermal comfort
No full textThe aim of this work is to simulate the Urban Heat Island (UHI) in a medium size Mediterranean city (Lecce, IT) and to analyze its consequences for thermal comfort. We use the Weather Research and Forecasting (WRF) model (version 3.2), that accounts for the urban structure with a multilayer urban parameterization (BEP+BEM i.e. the Building Effect Parameterization (BEP) combined with the Building Energy Model (BEM)). Three hot and cloudless summer days have been simulated and results have been compared with field data collected during an experimental campaign performed over the whole summer in the city of Lecce, Italy. In the model, the structure and shape of the city are reproduced using detailed data related to different urban classes, urban fraction and building morphometry. For the residential urban classes, different thermal parameters that are representative of building materials in the oldest and the newer part of the city, are used. Results show that UHI reaches, on average, its maximum intensity (4-5 °C) just before sunrise, and its minimum (2 °C) occurs during the day. Model validation inferred through statistical analysis shows overall a better model performance for the historical city centre than for the suburban area. This suggests that further refinement of the building representation in the outskirts might still be required. Consequences of the increased urban temperature are evaluated in terms of thermal comfort. The maximum thermal stress occurs during the central hours of the day, while, the minimum thermal stress occurs during the twilight hours
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Impact of single and combined local air pollution mitigation measures in an urban environment
Full text linkUrban air pollution is one of the most important environmental problems for human health and several strategies have been developed for its mitigation. The objective of this study is to assess the impact of single and combined mitigation measures on concentrations of air pollutants emitted by traffic at pedestrian level in the same urban environment. The effectiveness of different scenarios of green infrastructure (GI), the implementation of photocatalytic materials and traffic low emission zones (LEZ) are investigated, as well as several combinations of LEZ and GI. A wide set of scenarios is simulated through Computational Fluid Dynamics (CFD) modelling for two different wind directions (perpendicular (0°) and 45° wind directions). Wind flow for the BASE scenario without any measure implemented was previously evaluated using wind-tunnel measurements. Air pollutant concentrations for this scenario are compared with the results obtained from the different mitigation scenarios. Reduction of traffic emissions through LEZ is found to be the most effective single measure to improve local air quality. However, GI enhances the effects of LEZ, which makes the combination of LEZ + GI a very effective measure. The effectiveness of this combination depends on the GI layout, the intensity of emission reduction in the LEZ and the traffic diversion in streets surrounding the LEZ. These findings, in line with previous literature, suggest that the implementation of GI may increase air pollutant concentrations at pedestrian level for some cases. However, this study highlights that this negative effect on air quality can turn into positive when used in combination with reductions of local traffic emissions
Adaptation and mitigation of outdoor heat stress and building energy consumption during a heat wave in Nicosia, Cyprus
Full text linkCities in the Eastern Mediterranean and Middle East region face rising temperatures and intensifying heatwaves that are amplified by the urban heat island effect. These challenges pose significant threats to human health, agriculture, and the water-energy nexus, emphasizing the need for in-depth analysis and effective mitigation strategies at the urban scale. To address this need, we model the effects of seven interventions over 19 days, from July 23rd to August 10th, 2021, during a heatwave in Nicosia, Cyprus. We assess three key outcomes using the Weather Research and Forecasting (WRF) model coupled with the multilayer Building Energy Parameterization/Building Energy Model (BEP/BEM) scheme: 2m air temperature, outdoor heat stress, and air-conditioning energy use. Our results demonstrate that urban trees are the most effective single intervention, reducing energy consumption by approximately 46% and decreasing heat stress-degree hours by 20-25 h over the analyzed period. The combined implementation of cool roofs and urban trees proved to be the most effective overall, reducing energy consumption by over 50% and lowering 2m air temperatures by up to 1.2 degrees C during the day. A promising adaptive mitigation strategy emerged through the integration of photovoltaic panels and urban trees, which reduced heat stress while generating energy that significantly contributes to cooling demands. The efficacy of these interventions varied with urban geometry, with maximum benefits in areas characterized by medium building heights and densities. These findings offer guidance for developing urban climate resilience strategies in semi-arid regions, underscoring the importance of location-specific application of heat adaptation and mitigation measures
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Evaluating the performance of a novel WUDAPT averaging technique to define urban morphology with mesoscale models
No full textThe definition of accurate input datasets, appropriately representing urban morphology characteristics, has been identified as a crucial point for improving the simulation of urban boundary layer (UBL) dynamics by means of mesoscale numerical weather prediction (NWP) models. However, the scarcity of suitable data to adequately describe urban morphology is in many cases a significant obstacle to overcome. For this purpose, the World Urban Database Portal Tool (WUDAPT) framework was developed in order to obtain a standard classification of urban morphology, even in the absence of ad-hoc data for any city. In the present work, a modified WUDAPT method to define urban morphology is proposed and compared with two state-of-the-art methods, i.e. the standard WUDAPT method and a urban morphology parameters obtained from LIDAR data. In particular, here morphological features of Local Climate Zones (LCZs), resulting from a 30-m resolution WUDAPT classification, are interpolated to NWP cells, providing averaged features of the urban morphology. In this way, the method produces a unique value of the different urban morphology parameters for each model cell. This technique is tested by means of simulations with the Weather Research and Forecasting (WRF) model at 500 m resolution for the city of Bologna (Italy), located in the Po Plain. Simulation output is compared with measurements from weather stations. Results show that simulations using the modified WUDAPT method reproduce better atmospheric dynamics with respect to those implementing the standard WUDAPT method, and are comparable with simulations using the urban morphology defined with LIDAR data, considered as reference. In particular, the most relevant improvements are found in areas where LCZs are more heterogeneous and where the boundary between rural and urban areas is not clearly defined. It follows that the use of this method improves the classic WUDAPT method for small and scattered cities with respect to large and clustered urban areas, and can be particularly useful for urban areas where detailed LIDAR data are not available
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