In this work, we present a method to localize a source in complex urban environments using particle swarm optimization (PSO). Instead of using PSO to minimize the difference between a plume model and ...measurements as is often done, PSO is run such that each particle is modeled by an unmanned aerial vehicle (UAV) that measures and directly finds the global maximum of the concentration field. Several modifications were made to PSO to allow it to perform successfully in this application. The synthetic data used to test PSO were produced using the 3D building resolving Quick Urban & Industrial Complex Dispersion Modeling System (QUIC), and PSO was implemented in Python. Three different domains were tested: (1) a case with no obstacles, (2) a case with four large obstacles, and (3) a real-world case modeled after the Joint Urban 2003 experiment in Oklahoma City. We found that PSO works well in idealized and real cases. In the Oklahoma City simulation, approximately 90% of the PSO runs with 10 particles make it to within 1% of the maximum domain distance to the source, and approximately 98% of the PSO runs with 50 particles make it to within 1% of the maximum domain distance to the source. However, PSO is not completely immune to local maxima, and there is the possibility of convergence to the wrong point in the domain. The insight from this study can be used to inform first responders or create a tool that can be implemented on UAVs to locate a contaminant source.
•Particle swarm optimization can be used to find a contaminant source in a simulated plume.•Source localization was tested in hypothetical and realistic urban environments.•The algorithm is implemented on simulated mobile aerial robots (UAVs).•The algorithm has unique modifications which improve performance.•The plume was simulated using QUIC and incorporates turbulent information.
In the present paper, a computational study of the influence of solar and thermal radiation on the formation of wind and temperature conditions in urban environment is carried out using the example ...of an urban area of Krasnoyarsk in winter. For calculations, a developed microscale mathematical model of urban atmosphere was used. The calculation results showed that the presence of radiation in the daytime leads to an increase of temperature and average speed of wind, as well as to the formation of an unsteady wind regime in urban environment.
The paper aims to identify and analyze the factors influencing the selection of sites and buildings for the placement of creative hubs in the urban environment of the Czech Republic, where cultural ...and creative industries have been mapped (model cities Prague, Brno, Ostrava, Pilsen, Olomouc, and Zlín). Methodologically, the text is anchored both in the theoretical discussion of the concept of creative hubs and especially in qualitative research in the form of a questionnaire survey, semi-structured interviews with creative hub management, and on-site observation. Our research results have confirmed the experience of advanced economies (such as Germany or Austria) that creative hubs are naturally located in large cities, where sufficient economic and socio-cultural potential is also expected. However, even in smaller cities, increasing digitalization and technological advances are increasing the pressure to fill the “gap” in the creative economy. Regardless of the basic type of creative hub (creative space, co-working, maker space), the key factors affecting site selection are financial and investment costs, i.e. primarily acquisition costs, rental price and operating costs related to the city centre or off-centre location. Other strong factors are technical and transport infrastructure, a competitive environment, the concentration of potential customers and social infrastructure (especially a young and well-educated workforce). Last but not least, the wear and tear of the interior and exterior of the building and the social status of not only the surrounding area but also the city district appear to be an important element.
•Concentration of creative hubs in the Czech Republic is primarily dependent on the population size of the city and its economic strength and socio-cultural potential.•The most frequent factors influencing locality selection by city are: initial costs, price and rental options, operational costs competition, number of potential customers, availability of public transport, parking options.•Factors playing a role in object selection are: location, object size incl. Interior lay out, price and rental period, physical condition of the building, technical equipment, parking, public transport, object exterior and surroundings, connection between image of the building and image of the creative hub.
Cities in the developing world are expanding rapidly, and undergoing changes to their roads, buildings, vegetation, and other land use characteristics. Timely data are needed to ensure that urban ...change enhances health, wellbeing and sustainability. We present and evaluate a novel unsupervised deep clustering method to classify and characterise the complex and multidimensional built and natural environments of cities into interpretable clusters using high-resolution satellite images. We applied our approach to a high-resolution (0.3 m/pixel) satellite image of Accra, Ghana, one of the fastest growing cities in sub-Saharan Africa, and contextualised the results with demographic and environmental data that were not used for clustering. We show that clusters obtained solely from images capture distinct interpretable phenotypes of the urban natural (vegetation and water) and built (building count, size, density, and orientation; length and arrangement of roads) environment, and population, either as a unique defining characteristic (e.g., bodies of water or dense vegetation) or in combination (e.g., buildings surrounded by vegetation or sparsely populated areas intermixed with roads). Clusters that were based on a single defining characteristic were robust to the spatial scale of analysis and the choice of cluster number, whereas those based on a combination of characteristics changed based on scale and number of clusters. The results demonstrate that satellite data and unsupervised deep learning provide a cost-effective, interpretable and scalable approach for real-time tracking of sustainable urban development, especially where traditional environmental and demographic data are limited and infrequent.
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•Urban built and natural environments have multiple interrelated features.•Unsupervised deep learning applied to satellite images identified distinct environmental clusters.•Some clusters had dominant features like water, vegetation, and dense building and population.•Other clusters had multiple features like buildings surrounded by vegetation.•Our method can track urban change and support sustainable urban development.
The provision of water to meet the needs of an ever increasing urban population is a significant challenge. This is because urban receiving waters are constantly at risk from pollutant inputs via ...stormwater runoff and wastewater discharge. This research study employed multiple approaches including principal component analysis, Bayesian Networks (BNs) modelling and geospatial analysis to identify patterns in the distributions of nutrients and metals in water and sediments in an urban river and the interactions between the two phases. In both, water and sediments, nutrient concentrations/loads varied in the order of total carbon (TC) > total nitrogen (TN) > total phosphorus (TP). The river sediments were found to contain the highest crustal metal loads, while in water, the marine-related metals had the highest concentrations. The BNs modelling of pollutant interactions between water and sediment phases indicated that nitrogen is more likely to be transferred from water to sediment than the opposite, while anthropogenic metals are more likely to be transferred from sediments to water. Further, geospatial analysis showed that TN, crustal metals and anthropogenic metal loads in sediments increased from upstream to downstream, while having a decreasing pattern in water. However, marine-related metals in both, water and sediments had increasing concentrations/loads from upstream to downstream. These spatial patterns are attributed to the interactions between water and sediment phases, sediment transport along the river and seawater intrusion in the estuarine area. The study outcomes are expected to contribute to enhancing the knowledge required for developing mitigation strategies to improve urban receiving water quality.
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•Nutrient and metal transfer between river water and sediments was investigated.•Nitrogen is more likely to be transferred from water to sediment.•Anthropogenic metals are more likely to be transferred from sediments to water.•Pollutant loads in sediments and water have contrasting spatial distributions.
Nutrients and metals interactions between water and sediments were investigated using multiple data analysis approaches.
A number of studies have focused on urban trees to understand their mitigation capacity of air pollution. In this study particulate matter (PM) deposition on Quercus ilex leaves was quantitatively ...analyzed in four districts of the City of Terni (Italy) for three periods of the year. Fine (between 0.2 and 2.5 μm) and Large (between 2.5 and 10 μm) PM fractions were analyzed. Mean PM deposition value on Quercus ilex leaves was 20.6 μg cm−2. Variations in PM deposition correlated with distance to main roads and downwind position relatively to industrial area. Epicuticular waxes were measured and related to accumulated PM. For Fine PM deposited in waxes we observed a higher value (40% of total Fine PM) than Large PM (4% of total Large PM). Results from this study allow to increase our understanding about air pollution interactions with urban vegetation and could be hopefully taken into account when guidelines for local urban green management are realized.
•A quantitative analysis of Particulate Matter deposition on urban Quercus ilex leaves was implemented.•Deposition data were correlated with pollutants sources such as roads and local steel factory, and with epicuticular waxes.•Results provide new insight about the capacity of trees in removing pollutants in urban environment.
This paper is providing useful information on PM deposition on urban vegetation.
Wind flows inside complex urban environments are determined by the mutual effect of large-scale (i.e., wind above the urban boundary layer, UBL) and local-scale forcing (i.e. constraints into the ...urban canopy layer, UCL). Usually, when the wind field above the UBL is known (e.g. by on-site measurements, OsM), high-resolution microscale models (e.g. CFD) are used to predict the wind inside the UCL. However, standard procedures to map the wind field from an undisturbed position to the UCL are not available yet and several technical aspects need to be investigated. A downscaling method, so-called “static downscaling”, of the wind from mesoscale to microscale is innovatively adopted here to evaluate the performance of two CFD microscale models when predicting the flow in a UCL. The methodology is based on OsM transferred into the UCL by means of so-called “transfer coefficients” calculated by 3D steady RANS simulations for two different spatial extents of the explicitly modeled urban texture (Case A and B). It is discussed in detail the way the transfer coefficients work, how they can be used to understand the correlations between wind above and within the UCL as well as to identify the major limitations of the RANS approach. Results are discussed in qualitative terms and quantified using standard metrics. It is also shown that too high flow rates can occur at the entrance of the waterway of the area of interest and in the outer part of the explicitly modeled urban area, which can be mitigated by “buffer zones”.
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•On-site measurements were performed in Livorno city with LiDAR and anemometers.•RANS simulations on more and less spatially extended cases of Livorno city.•Transferred CFD data were compared to measured data inside the UCL at target points.•The extension of the environment surrounding the target area plays a key role.•Deviations are discussed and effects on wind flow quantified by statistical metrics.
After the 2020 Lunar New Year, the Chinese government implemented a strict nationwide lockdown to inhibit the spread of the Coronavirus Disease 2019 (COVID‐19). Despite the abrupt decreases in ...gaseous emissions caused by record‐low anthropogenic activities, severe haze pollution occurred in northern China during the COVID lockdown. This paradox has attracted the attention of both the public and the scientific community. By analyzing comprehensive measurements of air pollutants, planetary boundary layer (PBL) height, and surface meteorology, we show that the severe air pollution episode over northern China coincided with the abnormally low PBL height, which had reduced by 45%, triggering strong aerosol‐PBL interactions. After dynamical processes initiated the temperature inversion, the Beijing metropolitan area experienced a period with continuously shallow PBLs during the lockdown. This unprecedented event provided an experiment showcasing the role of meteorology, in particular aerosol‐PBL interactions in affecting air quality.
Key Points
Based on nationwide observations, variations in air pollution and meteorology are discussed during the COVID lockdown
The severe air pollution during the lockdown coincided with abnormally shallow PBL triggering strong aerosol‐PBL interactions
Beijing experienced a period with continuously shallow PBLs initiated by dynamical processes, which warrant the formation of haze event
Abstract
In a predominantly urban world, people’s ability to move within cities is a critical driver of sustainability. The transportation system which constitutes a large percentage of the physical ...urban environment provides mobility and aid economic sector. However, it contributes to several major environmental pressures including pollution, congestion, accidents, waste accumulation, resources depletion and disruption of nature. While urban population growth and increase in economic activities combine to generate higher demand for transportation services and heighten the problem. How to effectively deal with these imposing threats and simultaneously provide optimal mobility for city dwellers is the backbone of this research. Drawing experiences from developed cities, the study used Achara layout in Enugu as a case study. From observation, surveys and published literature data were collected and analysed qualitatively. The primary data include, physical traffic count, existing road character, traffic infrastructure and demographic statistics. Findings show the extensive sterility of Enugu’s urban infrastructure to motorized traffic and lack of provision for walking and cycling. It recommends strategies for planning and managing the urban environment which recognizes and acknowledged the social, environmental and economic realities. The conclusion demonstrates that cities designed for pedestrians and cyclist are cities designed for people and sustainable development.
Tree growth rate under urban limiting conditions Muscas, Desirée; Fornaciari, Marco; Proietti, Chiara ...
European journal of forest research,
12/2023, Letnik:
142, Številka:
6
Journal Article
Recenzirano
Odprti dostop
The benefits of green areas mostly depend on the trees’ dimension, which in the urban environment is not as predictable as it is in woodland. Growth models based on tree height and tree diameter at ...breast height have been largely employed to predict tree growth also in urbanised contexts. However, city environments differ from natural ones, and in addition to geographical influence, they present high variability in growth conditions within a few metres. Different urban conditions may influence tree vertical and diametral growth. The present study aims to jointly consider the effect of urban environment, maintenance practices and available space on the size growth of some tree species. Dendrometrical, space, management and status parameters of the sampled trees were collected during field surveys 14 years apart. Tree height and diameter at breast height data interpolations were realised and charted by an open-source graphing calculator to build three different growth equations (linear, logarithmic and logistic) for each of the five species considered regardless of tree growth conditions. The comparison between the comprehensive best-fitting models realised within this study and a USA inventory-based study highlighted quite similar tree growth trends, probably due to the consideration of both constrained and unconstrained trees. Furthermore, a study on the curves of same-growth condition trees of the same species was conducted. Generally, heavy pruning techniques such as control and pollard pruning, characterised by the removal of a consistent part of the tree crown, stand out as the main growth-limiting factor for the different species.
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