No description available.

Detailed photochemical modeling is used to guide air quality management activities around the world. These models use condensed chemical mechanisms to describe the multiphase processes that lead to chemical transformations in the atmosphere. Condensed mechanisms have generally not included the reactions of halogens, yet an expanding body of ambient observational evidence indicates that halogen chemistry, particularly chlorine chemistry, can be important in urban environments. This thesis is focused on the development, implementation, and evaluation of condensed chemical mechanisms that incorporate chlorine chemistry pathways. Gas phase reactions involving molecular chlorine and nitryl chloride (ClNO₂), as well as heterogeneous reactions involving particulate chloride species are addressed. The predictions of the modeling work presented here are compared to environmental chamber experiments and field observations. / text

(EN) This Diploma Thesis is concerned with statistical analysis of coarse aerosol at the area of the capital city Prague with focus on its time and space variability. The data covers time period from year 2005 up to year 2010 included. The concentrations of coarse aerosol were originally calculated from recorded values of PM10 a PM2,5. The assessment used in this thesis is based on concentrations of coarse aerosol recorded on four pollutant stations which are localized in the capital city. Three out of four those air pollution monitoring stations are characterized as traffic stations kind of purse, where we can assume the traffic's impact over the coarse aerosol concentration. The last station is distinguished to be background to report the data of region less loaded by pollution. The analysis is executed within particular parameters supposing that main source of coarse aerosol is traffic in urban environment. For time period examination variability the year, season, week and day running was carried out. The spatial variability was researched by the air pollution monitoring stations localization. To determine a rate of dependency among particular parameters the correlation analysis according to Spearman was used within the calculation of correlation coefficients. Beside the analysis this thesis...

Urban air quality management is a system for governments to lead cities towards achieving good air quality standards in an efficient way. Good air quality can avoid many environmental issues which are regarding air problems. At least, reduce environmental impacts efficiently in some extent. Carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), volatile organic compounds (VOC) and particulate matter (PM) are the common elements of air pollution. Topography, weather, the physical and chemical properties of pollutants and emission sources are also accomplices of air pollution. Östersund was a case study in this thesis because it has satisfactory air quality and won the European Mobility Week Award in 2014. Weather, winds, transportation and heating systems are the factors that influence urban air quality in Östersund. Green Traffic, Green Energy, and Green Highway are efficient projects in connection with air quality improvement in Östersund. Through successful technical application and institutional management, Östersund became one of the best climate cities in Sweden. This study is main focus on how Östersund municipality manages the local urban air quality then tries to find the suitable parts for China to learn. Here learn means find the suitable ways to improve urban air quality in China. It doesn’t mean copy all these projects. Emissions from vehicles, dust and the old style structures of energy are the main factors to reduce urban air quality in China. China did similar projects like Östersund did to improve urban air quality but the results were not so distinct so far. Vast land and large population are significant characteristics in China which make China’s ability slow to solve the air problem. Controlling the dust and emission from vehicles, using renewable resources and clean energy, optimizing industrial structure and complete legislations are beneficial projects to improve urban air quality in China. The projects of Green Traffic and Green Highway, and public participations are significant parts in Östersund which worth to learn for Chinese cities.

Several studies indicate that the cabin of buses is the micro-environment in urban public transport where commuters might be the most exposed to black carbon. Black carbon functions as an indicator of air pollution, which is shown to have harmful impacts on the human body and because it may lead to cancers, systemic inflammation, and cardiovascular diseases, it is listed as one of the top causes to premature deaths, globally. This makes it important to understand what mechanisms there are to the elevated levels of pollutants in urban buses, and by performing mobile in-cabin measurements of black carbon concentrations during 55 bus trips in the public transport system of Stockholm, this study have tried to assess the influences from using different types of fuel, self-contamination, meteorological conditions and driving factors. Although concentrations showed large variability both spatially and temporally, idling at intensely trafficked bus stops showed an average increase of concentrations by 42% compared to the overall average. The risk of allowing increased number of pollutants at bus stops increases with idling for longer time and having the doors open meanwhile.

<p dir="ltr">Urban air mobility (UAM) has the potential to revolutionize the transportation industry, offering fast, convenient, and sustainable travel options for passengers and cargo. The development and operation of UAM networks, however, face significant challenges, including the need for infrastructure investments and the management of grid electricity usage. In this thesis, we present a comprehensive model of UAM network operations based on system-of-systems engineering principles and employ a data-driven simulation framework to analyze the expected performance of a UAM operation. Our approach optimizes the composition of the UAM network, including the number of vehicles, chargers, and sizing of solar microgrids, to minimize total acquisition costs while adhering to operational constraints such as maximum average passenger delay and grid usage for each vertiport. Through the application of our methodology to diverse case studies, we provide valuable insights into the optimal design and integration of on-site microgrids for UAM vertiport networks, highlighting their impact on carbon emissions, operating costs, and grid electricity usage. This research contributes to the development of sustainable and efficient UAM systems, supporting informed decision-making among stakeholders involved in the planning, deployment, and operation of urban air mobility networks.</p>

Background: A continuously growing urban population leads to congested urban areas. As a result, people are wasting time being stuck in traffic. One way of solving this problem is to use the air for moving people. Thus, companies all over the globe are working extensively on approaches for Urban Air Mobility such as air taxis. Purpose: The purpose of this thesis is the identification of key determinants influencing the acceptance of air taxis from a potential user perspective. Thereby, the thesis develops the Urban Air Mobility Acceptance Model (UAMAM) as an extension of the Technology Acceptance Model (TAM). Method: An explanatory online survey was conducted to test the hypotheses in the proposed UAMAM. Data from 321 respondents living in cities larger than one million inhabitants representing the potential target group was collected. Partial Least Squares Structural Equation Modeling (PLS SEM) was used to assess the measurement model in terms of validity and reliability and the structural model in terms of hypotheses testing and strength of relationships between proposed variables. Further, a multigroup analysis has been examined to identify significant differences among groups. Conclusion: The results show that the attitude, which is strongly influenced by the perceived usefulness, as well as subjective norm, travel cost and the personal innovativeness are key determinants affecting the users’ behavioral intention to use air taxis. Further, moderating effects of age on the relation between time saving and behavioral intention as well as on the relation between personal innovativeness and behavioral intention were identified. Additionally, moderating effects of occupational status on the relation between travel cost and behavioral intention were found.

This dissertation investigates whether higher levels of “governmental fragmentation” in metropolitan statistical areas (MSA) leads to worse environmental outcomes. Fragmentation refers to the number of local governments in a given region or MSA as defined by the census. This research contributes to two bodies of literature, that of environmental federalism and that of urban growth and local government form. In the area of environmental federalism this dissertation extends the collective action model to include local governments. An empirical framework is developed that includes cross-sectional and panel data. In the urban growth and local government form literature, this dissertation comprehensively tests many existing measures of local government fragmentation within an environmental policy framework. It also modifies and extends some of the fragmentation variables. The results suggest that local government fragmentation does hinder MSAs from attaining the ozone standard. This dissertation extends the literature by examining the effect that local government fragmentation has on regional environmental quality. Six local government structure variables, jurisdiction count, special district dominance, central city dominance, county primacy, central city growth, and metropolitan power diffusion index are comprehensively tested to determine which might affect regional environmental quality. In addition, this research extends the use of the computationally complex measure of metropolitan power diffusion index to include additional local government expenditures as well as additional years of panel data. Two empirical estimation strategies were implemented, a cross-sectional approach and a panel data approach. The cross-sectional approach estimates the effects that long-term changes in local government structure have on attaining the ozone standard by measuring differences across MSAs. The panel data model’s primary purpose was that of a robustness check on the cross-sectional results. Three of the six tested fragmentation variables were found to have statistically significant effects on MSA attainment of the ozone standard in the cross-sectional model. Higher levels of metropolitan power diffusion index and jurisdiction count were found to hinder attainment of the ozone standard, while greater values of central city growth aided in reaching the attainment standard. Generally, the panel data results’ supported the results from the cross-sectional models. In addition, the panel model resolved some important estimation issues. Metropolitan power diffusion index was found to be correlated with unobservables in the random effects model, indicating that the cross-sectional results for metropolitan power diffusion index may be biased as well. This was not an issue for the variable jurisdiction count. Metropolitan power diffusion index and jurisdiction count are highly correlated with each other and this relationship was used to estimate a reasonable range for the effect metropolitan power diffusion index might have on the attainment of the ozone standard.

No description available.

<div>The National Aeronautics and Space Administration (NASA) has a vision for Advanced Air Mobility (AAM) based on safely introducing aviation services to missions that were previously not served or under-served. Many potential AAM missions lie in metropolitan areas that are beset by various types of uncertainty and potential constraints. Radio interference from other electronic devices can render unreliable communication between flying vehicles to ground operators. Buildings have irregular surfaces that degrade GPS localization performance. Skyscrapers can induce spontaneous turbulence that degrades vehicles' navigational accuracy. However, the potential market demands for aerial passenger-carrying and package delivery services have attracted investments. For example, Google WingX, Amazon Prime Air, and Joby Aviation are well-known companies developing AAM systems and services. If the market visions are realized, how will safety be assessed and maintained with high-density AAM operations?</div><div><br></div><div>While there are multiple technology candidates for realizing high-density AAM operations in urban environments, the means to accomplish the requisite first step of assessing the airspace safety of an integrated AAM eco-system from the candidate technologies is crucial but as yet unclear. This dissertation proposes an entropy-based framework for assessing the airspace safety level for low-altitude airspace in an AAM setting. The framework includes a conceptual model for depicting the information flows between air vehicles and an air traffic authority (ATA) and the use of a probability distribution to represent the traffic state. Subsequently, the framework embeds three airspace-level metrics for assessing airspace safety and uncertainty levels. The traffic safety severity metric quantifies the traffic safety level. The traffic entropy quantifies the uncertainty level of the traffic state distribution. Finally, the temperature is the ratio of the traffic safety severity to the traffic entropy. The temperature is similar to the traffic safety severity but gives a higher weight to the instance with a safe traffic state. </div><div><br></div><div>Simulation studies show that the combined use of the three metrics can evaluate relative airspace safety levels even if the unsafe conditions do not occur. The use cases include using the metrics for real-time airspace safety level monitoring and comparing the design of airspace systems and operational strategies. Additionally, this study demonstrates using a heat map to visualize vehicle-level metrics and assess designs of UAM airspace structures. The contribution of this study includes two parts. First, the temperature metric can heuristically assess a probability function. Based on the definition of the cost function, the temperature metric gives a higher weighting to the instance of the probability function with a lower cost value. This study constructs several triggers for predicting if a near-miss event would happen in the airspace. The temperature-based trigger has a better prediction accuracy than the cost-function-based trigger. Secondly, the temperature can visualize the safety level of an airspace structure with the considerations of the environmental and vehicle state measurement uncertainty. The locations with high-temperature values indicate that the regions are more likely to have endangered vehicles. Although this framework does not provide any means of resolving the unsafe conditions, it can be powerful in the comparison of different airspace design concepts and identify the weaknesses of either airspace design or operational strategies. </div>