DRUM - Digital Repository at the University of Maryland

DRUM collects, preserves, and provides public access to the scholarly output of the university. Faculty and researchers can upload research products for rapid dissemination, global visibility and impact, and long-term preservation.

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To submit an item to DRUM, login using your UMD credentials. Then select the "Submit Item to DRUM" link in the navigation bar. View DRUM policies and submission guidelines.

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The University of Maryland Equitable Access Policy provides equitable, open access to the University's research and scholarship. Faculty can learn more about what is covered by the policy and how to deposit on the policy website.

Theses and Dissertations

DRUM includes all UMD theses and dissertations from 2003 forward.

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Archaeology in Annapolis

Barrio de Langley Park

Recent Submissions

The Effects of Spanwise Stiffness on Thrust Generation in Flexible Pitching Fins
(2026-04-22) Stasik, Michelle; Mukhopadhyay, Adhiraj; Huertas Cerdeira, Cecilia
Prior numerical studies suggest that stiffness gradients in bio-inspired fish fins can enhance thrust through favorable fluid-structure interactions, but physical validation remains limited. As such, this study experimentally investigates whether spanwise stiffness variations in additively manufactured fins produce measurable differences in thrust and thereby propulsive performance. Four fins with identical geometry, but differing stiffness profiles were tested: a baseline uniform configuration without variable stiffness, as well as a cupping, W-shaped, and heterocercal distribution. Each fin was driven in a prescribed pitching motion within a water tank and the resulting thrust forces were measured using a low-friction force measurement system. Signal processing procedures were then used to mitigate experimental noise and obtain reliable mean thrust values for comparing fin performance. It was determined that at lower pitching frequencies (0.70–0.80 Hz), mean thrust differences between different distributions were small and comparable to the experimental uncertainty, indicating that thrust production was governed largely by the flapping motion. At higher frequencies (0.85–0.90 Hz), clear performance separation emerged. All variable-stiffness fins produced greater thrust than the uniform configuration, with the W-shaped distribution generating the highest mean thrust. At 0.90 Hz, the maximum difference between configurations exceeded the experimental uncertainty by more than twenty-five times. These results demonstrate that stiffness gradients significantly influence thrust under hydrodynamic loading and can inform the design of more efficient passive propulsion systems.
VACANT AND/OR UNDERUTILIZED RELIGIOUS PROPERTIES IN MARYLAND: ENVISIONING HEALTHY PLANNING TRANSITIONS
(2026-01-01) Aghili, Homayoon; Arazi, David; Assaker, Maya; Carey, Noah; Espejo, Pablo; Kamei Hoffman, Sarah; Johnson, Dejuan; Lawrence, John; Sheikh, Insha; Irazabal, Clara; Exantus, Jordan
This report presents the work of the Fall 2025 University of Maryland URSP 708 Community Planning Studio, examining the challenges and opportunities associated with vacant and underutilized religious properties in Maryland. Declining religious participation, aging facilities, and increasing financial pressures have placed significant strains on religious institutions, while creating opportunities for adaptive reuse and community-serving redevelopment. Through contextual research, literature review, site and market analyses, planning and design evaluations, and community engagement, the Studio examined three religious properties in Prince George’s County: Carolina Missionary Baptist Church in Fort Washington, Church of the Living God in Adelphi, and St. Christopher’s Episcopal Church in New Carrollton. Working with church partners and community stakeholders, students evaluated existing development proposals and developed alternative strategies that respond to each institution’s mission, site conditions, financial capacity, and surrounding community needs. Recommendations include integrating supportive and affordable housing with workforce development, creating wellness-oriented and intergenerational communities, improving pedestrian accessibility, and combining affordable housing, worship facilities, resilience infrastructure, and complementary commercial uses within mixed-use developments. Across the three case studies, the findings emphasize the importance of balancing mission-driven development with financial feasibility, regulatory constraints, environmental considerations, and meaningful community engagement. The report highlights the role of religious institutions as community anchors and potential mission-driven developers, demonstrating how context-sensitive planning, strategic partnerships, and integrated land uses can support sustainable transitions that benefit both congregations and their surrounding communities.
Essays on Production Economics
(2026) Wang, Shuo; Chambers, Robert G; Agricultural and Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
This dissertation consists of three essays on production economics. Each essay develops and applies structural models to study how producers adapt to uncertainty, weather variability, and pest pressure. The first essay proposes a theory-supervised prediction framework that jointly predicts realized output, total cost, and input demands through an economic model of cost-minimizing behavior. A neural network imputes the unobserved counterfactual outputs, and cost-minimization restrictions discipline these imputations. Applied to three Australian broadacre agricultural zones (1979–2010), the estimator yields moderate transformation elasticities, indicating meaningful but limited capacity to reallocate production across weather events. The second essay develops a structural model to decompose weather impacts on mixed crop-livestock farming systems into output transformation and input adaptation effects. Using longitudinal data from New South Wales, Australia, the analysis shows that water availability is the dominant constraint on farm profitability and that input adaptation partially offsets weather-induced production losses. The third essay investigates the persistence of intensive pesticide use in Chinese cotton production despite the widespread adoption of Bt cotton. Using a damage-control framework embedded in a dual cost structure, the analysis reveals that pest vulnerability declined following Bt diffusion but subsequently rebounded, and that corrective policies would impose substantial private costs on farmers.
MECHANISMS OF MICROBIOTA‑DRIVEN IMMUNE REGULATION IN THE TUMOR MICROENVIRONMENT
(2026) Lam, Khiem Chi; El-Sayed, Najib; Cell Biology & Molecular Genetics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Gut microbiota has emerged as a critical regulator of anti-cancer immunity, yet the mechanisms by which microbial cues shape the tumor microenvironment (TME) remain ill-defined, hampering the development of effective microbiota-targeted interventions. This dissertation addressed this gap by adopting a TME-centric approach, combining single-cell analyses of immune cells across diverse gut microbiota conditions in preclinical models followed by validation with human samples and published datasets. These studies identify a role for microbiota-derived stimulator of interferon genes (STING) agonists in driving type I interferon (IFN) responses in intratumoral monocytes. Such signals program immunostimulatory macrophages and enhance crosstalk between natural killer and dendritic cells. In addition, microbiota-targeted interventions (e.g., supplementation with soluble fiber pectin) remodel the gut microbiome to induce this type I IFN pathway, enhance effector T cell function, and improve tumor control and response to immune checkpoint blockade therapies. Extending this analysis across 19 syngeneic tumor models further demonstrates that the efficacy of microbiota-targeted interventions is not universal but instead depends on tumor-intrinsic factors such as cancer type, immune state, and metabolic requirements. Collectively, this dissertation defines the cellular and molecular mechanisms by which gut microbiota programs the TME to support anti-tumor immunity and identifies key determinants that govern such responses. These findings provide a framework for the development of microbiota-targeted strategies to improve outcomes for individuals with cancer.
A SPECTRAL DATA ASSIMILATION SYSTEM FOR WAVEWATCH III USING THE FOUR-DIMENSIONAL LOCAL ENSEMBLE TRANSFORM KALMAN FILTER
(2026) DiPasqua, Samuel; Ide, Kayo; Mathematics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Ocean waves are created from energy passing through water with severe weather, such ashurricanes, creating hazardous waves. These hazardous waves pose risks to offshore operations, maritime operations, and coastal communities. Accurate wave forecasting provides critical information to these fields. Conventional wave data assimilation (DA) systems typically update mean wave parameters such as significant wave height, which limits their ability to represent the full wave spectrum and enforce physical consistency. This dissertation develops and evaluates a spectral wave data assimilation system for WAVEWATCH III based on the Local Ensemble Transform Kalman Filter. The LETKF analysis directly updates weights of the ensemble members, which makes it a versatile analysis for updating different analysis control variables. This proposed system introduces a logarithmically transformed spectral analysis control variable to weakly constrain the non-negative model state from WAVEWATCH III. Then, the 3D and 4DLETKF are compared to determine the impact of incorporating the model trajectory into the analysis. Lastly, shortest path and shortest distance localization are compared to determine the impact of observations across landmasses. Together, these factors result in a unique wave DA system that focuses on improving the physical characteristics of the wave spectrum. Observing system simulation experiments (OSSEs) were performed using significant wave height observations from buoys and satellite altimeters. Results show that spectrally-averaged root mean square error (RMSE) is similar across the different tested analysis control variables at the time of analysis. However, the analysis in significant wave height space reveals more meaningful corrections in RMSE and bias over a 24 hr forecast period. In significant wave height forecasts, changing the analysis control variable leads to significantly different forecasts. Comparisons between 3D and 4D-LETKF configurations demonstrate that 4D DA achieves persistent improvements to significant wave height forecast skill across each of the analysis control variables. The comparison between shortest path and shortest distance localization shows minimal aggregate differences because of the limited regions affected by the change in localization method and because the model, WAVEWATCH III, is wind-driven. These findings demonstrate the importance of the analysis control variable and wave evolution for wave DA systems.