نتایج جستجو برای: urban street canyon
تعداد نتایج: 199277 فیلتر نتایج به سال:
In densely populated areas, traffic is a significant source of atmospheric aerosol particles. Owing to their small size and complicated chemical and physical characteristics, atmospheric particles resulting from traffic emissions pose a significant risk to human health and also contribute to anthropogenic forcing of climate. Previous research has established that vehicles directly emit primary ...
Abstract. This study investigated the sources of black carbon (BC) at two contrasting urban environments in Helsinki, Finland: residential area and street canyon. The measurement campaign was conducted winter–spring 2019, whereas canyon measurements were carried out autumn 2015. BC explored by using positive matrix factorization (PMF) for organic refractory (rBC) mass spectra collected with a s...
Abstract. Trees provide many ecosystem services in cities such as urban heat island reduction, water runoff limitation, and carbon storage. However, the presence of trees street canyons reduces wind velocity limits pollutant dispersion. Thus, to obtain accurate simulations concentrations, aerodynamic effect should be taken into account air quality models at level. The Model Urban Network Inters...
Detailed computational simulations of turbulent flows and pollution dispersion in city canyons have been carried out using the computational fluid dynamics package CFX-5, which is capable of using unstructured meshes and a variety of turbulence closure schemes. The simulations have been done for city canyons with simple to complex structures. As a validation of CFX-5, a roof garden test is cond...
Spatial distribution of momentum flux and moments of third order of velocity components obtained from one-point measurement are investigated. The area of interest covers an inner part of street canyon and adjacent intersection. Timeaveraged momentum flux were divided into particular quadrants using Quadrant Analysis method. Comparison between flux events and skewness provides some insight into ...
Large-eddy simulation (LES) is used to systematically analyse the impacts of trees on air quality in idealised street canyons. The LES tree model includes radiation, transpiration, drag and deposition effects. superposition background concentrations local emissions construct realistic urban scenarios for fine particulate matter (PM2.5) nitrogen oxides (NOx). Both neutral convective atmospheric ...
Cities experience overheating due to factors such as urban form and materials, concentration of human activities, reduction in the amount vegetation water surfaces. Vegetation is one ways reduce temperature peaks city during heat waves. The objectives this paper are twofold: first, study impact on microclimate a north-south oriented canyon street at reduced-scale (1/5), then well-watered trees ...
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