Since the transportation sector still relies mostly on fossil fuels, the emissions and overall environmental impacts of the transportation sector are particularly relevant to the mitigation of the adverse effects of climate change. Sustainable transportation therefore plays a vital role in the ongoing discussion on how to promote energy insecurity and address future energy requirements. One of the most promising ways to increase energy security and reduce emissions from the transportation sector is to support alternative fuel technologies, including electric vehicles (EVs). As vehicles become electrified, the transportation fleet will rely on the electric grid as well as traditional transportation fuels for energy. The life cycle cost and environmental impacts of EVs are still very uncertain, but are nonetheless extremely important for making policy decisions. Moreover, the use of EVs will help to diversify the fuel mix and thereby reduce dependence on petroleum. In this respect, the United States has set a goal of a 20% share of EVs on U.S. roadways by 2030. However, there is also a considerable amount of uncertainty in the market share of EVs that must be taken into account. This dissertation aims to address these inherent uncertainties by presenting two new models: the Electric Vehicles Regional Optimizer (EVRO), and Electric Vehicle Regional Market Penetration (EVReMP). Using these two models, decision makers can predict the optimal combination of drivetrains and the market penetration of the EVs in different regions of the United States for the year 2030. First, the life cycle cost and life cycle environmental emissions of internal combustion engine vehicles, gasoline hybrid electric vehicles, and three different EV types (gasoline plug-in hybrid EVs, gasoline extended-range EVs, and all-electric EVs) are evaluated with their inherent uncertainties duly considered. Then, the environmental damage costs and water footprints of the studied drivetrains are estimated. Additionally, using an Exploratory Modeling and Analysis method, the uncertainties related to the life cycle costs, environmental damage costs, and water footprints of the studied vehicle types are modeled for different U.S. electricity grid regions. Next, an optimization model is used in conjunction with this Exploratory Modeling and Analysis method to find the ideal combination of different vehicle types in each U.S. region for the year 2030. Finally, an agent-based model is developed to identify the optimal market shares of the studied vehicles in each of 22 electric regions in the United States. The findings of this research will help policy makers and transportation planners to prepare our nation*s transportation system for the future influx of EVs. The findings of this research indicate that the decision maker*s point of view plays a vital role in selecting the optimal fleet array. While internal combustion engine vehicles have the lowest life cycle cost, the highest environmental damage cost, and a relatively low water footprint, they will not be a good choice in the future. On the other hand, although all-electric vehicles have a relatively low life cycle cost and the lowest environmental damage cost of the evaluated vehicle options, they also have the highest water footprint, so relying solely on all-electric vehicles is not an ideal choice either. Rather, the best fleet mix in 2030 will be an electrified fleet that relies on both electricity and gasoline. From the agent-based model results, a deviation is evident between the ideal fleet mix and that resulting from consumer behavior, in which EV shares increase dramatically by the year 2030 but only dominate 30 percent of the market. Therefore, government subsidies and the word-of-mouth effect will play a vital role in the future adoption of EVs.

Agent-based simulation models are an important tool to study the effectiveness of policy interventions on the uptake of residential photovoltaic systems by households, a cornerstone of sustainable energy system transition. In order for these models to be trustworthy, they require rigorous validation. However, the canonical approach of validating emulation models through calibration with parameters that minimize the difference of model results and reference data fails when the model is subject to many stochastic influences. The residential photovoltaic diffusion model PVact features numerous stochastic influences that prevent straightforward optimization-driven calibration. From the analysis of the results of a case-study on the cities Dresden and Leipzig (Germany) based on three error metrics (mean average error, root mean square error and cumulative average error), this research identifies a parameter range where stochastic fluctuations exceed differences between results of different parameterization and a minimization-based calibration approach fails. Based on this observation, an approach is developed that aggregates model behavior across multiple simulation runs and parameter combinations to compare results between scenarios representing different future developments or policy interventions of interest.

Many infectious diseases are spread through interactions between susceptible and infectious individuals. Keeping track of where each exposure to the disease took place, when it took place, and which individuals were involved in the exposure can give public health officials important information that they may use to formulate their interventions. Further, knowing which individuals in the population are at the highest risk of becoming infected with the disease may prove to be a useful tool for public health officials trying to curtail the spread of the disease. Epidemiological models are needed to allow epidemiologists to study the population dynamics of transmission of infectious agents and the potential impact of infectious disease control programs. While many agent-based computational epidemiological models exist in the literature, they focus on the spread of disease rather than exposure risk. These models are designed to simulate very large populations, representing individuals as agents, and using random experiments and probabilities in an attempt to more realistically guide the course of the modeled disease outbreak. The work presented in this thesis focuses on tracking exposure risk to chickenpox in an elementary school setting. This setting is chosen due to the high level of detailed information realistically available to school administrators regarding individuals' schedules and movements. Using an agent-based approach, contacts between individuals are tracked and analyzed with respect to both individuals and locations. The results are then analyzed using a combination of tools from computer science and geographic information science.

No description available.

<p>Human disease and the corresponding immune response occur in three-dimensional space and time. Many diseases are difficult to study, either <em>in vivo</em> or <em>in vitro</em>, due to the complexity of the system. Despite computational models that can address complexity, many do not capture the spatial  aspects  of  disease.  Agent-based  models  are  mechanistic,  spatiotemporal  computational models that can be integrated with other mathematical models to create multiscale models. Here I detail two models to examine spatiotemporal progression and possible treatment strategies for two diseases  with  low  treatment  success: <em>Mycobacterium  avium complex</em>  (MAC)  and  Alzheimer’s Disease.</p> <p>MAC  are  biofilm-forming  environmental  microbes  capable  of  residing  in  human  lung nodules,  causing  MAC  pulmonary  disease  (MAC-PD).  Clinical  drug  susceptibility  tests  and treatment  outcomes  are  poorly  correlated,  and  nodules  are  complex  and  difficult  to  monitor, leading to low MAC cure rates (45-65%)². I have developed an informative model of the initial infection  events  in  MAC-PD. This  model  has  been  used  to  probe  many  different  scenarios  of infection and to predict the effect of potential interventions.</p> <p>Alzheimer’s  Disease  (AD)  is  the  leading  cause  of  dementia,  with  no  disease-altering pharmacological  intervention.  Microglia  are  phagocytotic  neuroimmune  cells,  known  to  form barriers around plaques. There has been increased interest in leveraging microglia to slow the progression of neurodegeneration by manipulating these barriers. I present an agent-based model of microglia barriers at the single plaque level and use knock-out experiments to probe possible targets for immunotherapy and quantify their effects on plaque progression.</p>

Coastal socio-ecological systems face unprecedented challenges due to climate change, with impacts encompassing long-term, chronic changes and short-term extreme events. These events will impact society in many ways and prompt human responses that are extremely challenging to predict. This dissertation employs complex systems methods of agent-based modeling and machine learning to simulate the interactions between climatic stressors such as increased flooding and extreme weather and socio-economic aspects of coastal human systems. Escalating sea-level rise and intensified flooding has the potential to prompt relocation from flood-prone coastal areas. This can reduce flood exposure but also disconnect people from their homes and communities, sever longstanding social ties, and lower the tax base leading to difficulties in providing government services. Chapter 2 demonstrates a stochastic agent-based model to simulate human relocation influenced by flooding events, particularly focusing on the responses of rural and urban communities in coastal Virginia and Maryland. The findings indicate that a stochastic, bottom-up social system simulator is able to replicate top-down population projections and provide a baseline for assessing the impact of increasingly intense flooding. Chapter 3 leverages this model to assess how incorporating heterogeneity in relocation decisions across socio-economic groups impacts flood-induced relocation patterns. The results demonstrate how this heterogeneity leads to a decrease in low-income households, yet a rise in the proportion of elderly individuals in flood-prone regions by the end of the simulation period. Flood-prone areas also exhibit distinct income clusters at the end of simulation time horizon compared to simulations with a homogenous relocation likelihood. Lastly, Chapter 4 explores relationships between extreme weather and agricultural losses in the Delmarva Peninsula. Existing research on climatic impacts to agriculture largely focuses on changes to major crop yields, providing limited insights into impacts on diverse regional agricultural systems where human management and adaptation play a large role. By comparing various multistep modeling configurations and machine learning techniques, this work demonstrates that machine learning methods can accurately simulate and predict agricultural losses across the complex agricultural landscape that exists on the Delmarva peninsula. The multistep configurations developed in this work are able to address data imbalance and improve models' capacity to classify and estimate damage occurrence, which depends on multiple geographical, seasonal, and climatic factors. Collectively, this work demonstrates the potential for advanced modeling techniques to accurately replicate and simulate the impacts of climate on complex socio-ecological systems, providing insights that can ultimately support coastal adaptation. / Doctor of Philosophy / Coastal areas are facing increasing challenges from climate change, including rising sea levels and extreme weather conditions. This dissertation explores socio-economic consequences of these adverse environmental changes for coastal communities. Disruptive repetitive flooding due to exacerbated rise in sea levels is one of these consequences that may eventually leave some highly exposed coastal communities no alternative but migrating from their residences. Focusing on coastal Virginia and Maryland, Chapter 2 develops a data-informed model that can simulate individual relocation decisions and assess how they impact population changes and migration patterns. Chapter 3 employs this model to investigate how future changes in sea levels affect diverse socio-economic groups, their relocation decisions, and the resulting collective migration flows in flood-prone areas. We found that considering demographic differences leaves highly flood-prone areas with less low-income households, higher elderly individuals, and more economic clusters compared to simulations where these differences are not accounted for. Chapter 4 uses machine learning models to simulate the economic impact of extreme weather events as another manifestation of climate change on the agriculture in the Delmarva Peninsula. Through data-based modeling techniques, we identify the climatic conditions most responsible for agricultural losses and recognize modeling choices that enhance our predictive ability. Collectively, this dissertation demonstrates how sophisticated modeling techniques can be used to better understand the complex ways in which climate change will impact human society, with the ultimate goal of supporting adaptation strategies that can better address these impacts.

During the early stages of any epidemic, simple interventions such as quarantine and isolation may be sufficient to halt the spread of a novel pathogen. However, should this opportunity be missed, substantially more resource-intensive, complex, and societally intrusive interventions may be required to achieve an acceptable outcome. These disparities place a differential on the value of a given unit of knowledge across the time-domains of an epidemic. Within this dissertation we explore these value-differentials via extension of the business concept of the time-value of knowledge and propose the C4 Response Model for organizing the research response to novel pathogenic outbreaks. First, we define the C4 Response Model as a progression from an initial data-hungry collect stage, iteration between open-science-centric connect stages and machine-learning centric calibrate stages, and a final visualization-centric convey stage. Secondly we analyze the trends in knowledge-building across the stages of epidemics with regard to open and closed access article publication, referencing, and citation. Thirdly, we demonstrate a Twitter message mapping application to assess the virality of tweets as a function of their source-profile category, message category, timing, urban context, tone, and use of bots. Finally, we apply an agent-based model of influenza transmission to explore the efficacy of combined antiviral, sequestration, and vaccination interventions in mitigating an outbreak of an influenza-like-illness (ILI) within a simulated military base population. We find that while closed access outbreak response articles use more recent citations and see higher mean citation counts, open access articles are published and referenced in significantly greater numbers and are growing in proportion. We observe that tweet viralities showed distinct heterogeneities across message and profile type pairing, that tweets dissipated rapidly across time and space, and that tweets published before high-tweet-volume time periods showed higher virality. Finally, we saw that while timely responses and strong pharmaceutical interventions showed the greatest impact in mitigating ILI transmission within a military base, even optimistic scenarios failed to prevent the majority of new cases. This body of work offers significant methodological contributions for the practice of computational epidemiology as well as a theoretical grounding for the further use of the C4 Response Model. / Doctor of Philosophy / During the early stages of an outbreak of disease, simple interventions such as isolating those infected may be sufficient to prevent further cases. However, should this opportunity be missed, substantially more complex interventions such as the development of novel pharmaceuticals may be required. This results in a differential value for specific knowledge across the early, middle, and late stages of epidemic. Within this dissertation we explore these differentials via extension of the business concept of the time-value of knowledge, whereby key findings may yield greater benefits during early epidemics. We propose the C4 Response Model for organizing research regarding this time-value. First, we define the C4 Response Model as a progression from an initial knowledge collection stage, iteration between knowledge connection stages and machine learning-centric calibration stages, and a final conveyance stage. Secondly we analyze the trends in knowledge-building across the stages of epidemics with regard to open and closed access scientific article publication, referencing, and citation. Thirdly, we demonstrate a Twitter application for improving public health messaging campaigns by identifying optimal combinations of source-profile categories, message categories, timing, urban origination, tone, and use of bots. Finally, we apply an agent-based model of influenza transmission to explore the efficacy of combined antiviral, isolation, and vaccination interventions in mitigating an outbreak of an influenza-like-illness (ILI) within a simulated military base population. We find that while closed access outbreak response articles use more recent citations and see higher mean citation counts, open access articles are growing in use and are published and referenced in significantly greater numbers. We observe that tweet viralities showed distinct benefits to certain message and profile type pairings, that tweets faded rapidly across time and space, and that tweets published before high-tweet-volume time periods are retweeted more. Finally, we saw that while early responses and strong pharmaceuticals showed the greatest impact in preventing influenza transmission within military base populations, even optimistic scenarios failed to prevent the majority to new cases. This body of work offers significant methodological contributions for the practice of computational epidemiology as well as a theoretical grounding for the C4 Response Model.

Developments of commercial self-driving vehicle (SDV) technology has a potential for a paradigm shift in traffic control technology. Contrary to some previous research approaches, this research argues that, as any other technology, traffic control technology for SDVs should be developed having in mind improved quality of life through a sustainable developmental approach. Consequently, this research emphasizes upon the social perspective of sustainability, considering its neglect in the conventional control principles, and the importance of behavioral considerations for accurately predicting impacts upon economic or environmental factors. The premise is that traffic control technology can affect the distribution of advantages and disadvantages in a society, and thus it requires a framework of social justice. The framework of social justice is inspired by John Rawls' Theory of Justice as fairness, and tries to protect the inviolability of each user in a system. Consequently, the control objective is the distribution of delay per individual, considering for example that the effect of delay is not the same if a person is traveling to a grocery store as opposed to traveling to a hospital. The notion of social justice is developed as a priority system, with end-user responsibility, where user is able to assign a specific Priority Level for each individual trip with SDV. Selected Priority Level is used to determine the right-of-way for each self-driving vehicle at an intersection. As a supporting mechanism to the priority system, there is a structure of non-monetary Priority Credits. Rules for using Priority Credits are determined using knowledge from social science research and through empirical evaluation using surveys, interviews, and web-based experiment. In the physical space, the intersection control principle is developed as hierarchical self-organization, utilizing communication, sensing, and in-vehicle technological capabilities. This distributed control approach should enable robustness against failure, and scalability for future expansion. The control mechanism has been modeled as an agent-based system, allowing evaluation of effects upon safety and user delay. In conclusion, by reaching across multiple disciplines, this development provides the promise and the challenge for evolving SDV control technology. Future efforts for SDV technology development should continue to rely upon transparent public involvement and understanding of human decision-making. / Ph. D.

<p dir="ltr">This dissertation investigates strategic decision-making under conditions of environmental inequality. The three chapters explore various forms of inequality across different decision contexts</p><p dir="ltr">The first chapter examines the impact of income inequality on individuals' participation in multiple public goods investments. Specifically, it analyzes how a global club good opportunity influences local public goods provision in indefinitely repeated interactions within a linear public goods game using a voluntary contribution mechanism. The study varies global club entry costs and local community endowment compositions to assess their effects on contributions and welfare. It finds that income inequality does not significantly alter contribution behaviors in single public good settings under indefinitely repeated interactions. With the introduction of a global club good, lower entry costs lead to higher participation rates among subjects, resulting in increased total welfare for both homogeneous and heterogeneous communities. Conversely, higher entry costs reduce participation and overall welfare. Heterogeneous communities discontinue club use sooner than homogeneous ones. Efficiency, measured as realized payoff relative to maximal social benefits, declines across all treatments following the introduction of a global club good. Additionally, counterfactual simulations using an individual evolutionary learning model demonstrate that the welfare benefits of a global club good opportunity hinge on its ability to yield substantial social benefits compared to local public goods.</p><p dir="ltr">The second chapter explores how power inequality influences cooperation in a dynamic game where competition and cooperation evolve over time. This research, conducted as part of a collaborative project with Yaroslav Rosokha, Denis Tverskoi, and Sergey Gavrilets, examines cooperation dynamics in scenarios where cooperation's benefits depend on political power derived from a contest. The study highlights that incumbency advantages in political contests precipitate a rapid breakdown of cooperation within social dilemmas. Furthermore, it investigates behavioral disparities between groups and individuals, leveraging simulations based on the Arifovic and Ledyard (2012) individual evolutionary learning model to shed light on the difference observed in the experiment.</p><p dir="ltr">The third chapter investigates the impact of unequal positions in a directed communication network on individuals' optimal stopping rules and social learning outcomes. The study involves subjects making predictions about uncertain states of the world using private information and social information obtained through a directed network. Theoretical predictions suggest that individuals should wait when the benefit of waiting exceeds the associated cost. Empirical results confirm that subjects indeed wait longer in more connected networks or when waiting costs are low. However, deviations from equilibrium predictions indicate influences of bounded rationality (supported by quantal response equilibrium) and heuristic decision-making, where some subjects consistently wait for a single turn regardless of positional advantage. Importantly, under-waiting at an information aggregator's position has negative externalities on group-wide information acquisition.</p>

<p dir="ltr">In my dissertation, I examine the dynamics of digital platforms, starting with the governance practices of established platforms, then exploring innovative design approaches, and finally the integration of advanced AI technologies in platforms. I structure this exploration into three essays: in the first essay, I discuss moderation processes in online communities; in the second, I propose a novel design for a blockchain-based green bond exchange; and in the third, I examine how AI-based decision-making platforms can be enhanced through synthetic data generation.</p><p dir="ltr">In my first essay, I investigate the role of moderation in online communities, focusing on its effect on users' participation in community moderation. Using data from a prominent online forum, I analyze changes in users' moderation actions (upvoting and downvoting of others' content) after they experience a temporary account suspension. While I find no significant change in their upvoting behavior, my results suggest that users downvote more after their suspension. Combined with findings on lower quality and conformity with the community while downvoting, the results suggest an initial increase in hostile moderation after suspension, although these effects dissipate over time. The short-term hostility post-suspension has the potential to negatively affect platform harmony, thus revealing the complexities of disciplinary actions and their unintended consequences.</p><p dir="ltr">In the second essay, I shift from established platforms to innovations in platform design, presenting a novel hybrid green bond exchange that integrates blockchain technology with thermodynamic principles to address market volatility and regulatory uncertainty. The green bond market, despite its high growth, faces issues like greenwashing, liquidity constraints, and limited retail investor participation. To tackle these challenges, I propose an exchange framework that uses blockchain for green bond tokenization, enhancing transparency and accessibility. By conceptualizing the exchange as a thermodynamic system, I ensure economic value is conserved and redistributed, promoting stability and efficiency. I include key mechanisms in the design to conserve value in the exchange and deter speculative trading. Through simulations, I demonstrate significant improvements in market stability, liquidity, and efficiency, highlighting the effectiveness of this interdisciplinary approach and offering a robust framework for future financial system development.</p><p dir="ltr">In the third essay, I explore the integration of advanced AI technologies, focusing on how large language models (LLMs) like GPT can be adapted for specialized fields such as education policy and decision-making. To address the need for high-quality, domain-specific training data, I develop a methodology that combines agent-based simulation (ABS) with synthetic data generation and GPT fine-tuning. This enhanced model provides accurate, contextually relevant, and interpretable insights for educational policy scenarios. My approach addresses challenges such as data scarcity, privacy concerns, and the need for diverse, representative data. Experiments show significant improvements in model performance and robustness, offering policymakers a powerful tool for exploring complex scenarios and making data-driven decisions. This research advances the literature on synthetic data in AI and agent-based modeling in education, demonstrating the adaptability of large language models to specialized domains.</p>