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A Study of Cloud Seeding in Wintertime Orographic Clouds
Get PDFCloud seeding has long been investigated as an approach to enhance snowpack in wintertime orographic clouds, yet its efficiency and underlying physical mechanisms remain uncertain. This dissertation explores the effectiveness of cloud seeding by integrating observational data and high-resolution numerical simulations. The study is grounded in data from the Seeded and Natural Orographic Wintertime Clouds: The Idaho Experiment (SNOWIE), a comprehensive field campaign in the Payette Mountains of Idaho that combined airborne and ground-based observations from January to March 2017.
This research addresses three critical aspects of wintertime orographic cloud seeding: (1) the influence of synoptic weather patterns and topographical features on the variability of natural snowfall and the suitability of cloud seeding practices, (2) the cloud microphysical responses to cloud seeding, and (3) the effectiveness of cloud seeding in enhancing ice initiation, as simulated using the Weather Research and Forecasting (WRF) model integrated with a cloud-seeding parameterization (WRF-WxMod).
The main results reveal that (1) cloud microphysical properties, such as ice water content (IWC) and supercooled liquid water (SLW), as well as snowfall distribution, are affected by synoptic-scale moisture transport, temperature advection, and local topographical lifting processes. Specifically, warm zonal flow (WZF) synoptic patterns displayed a lower IWC but substantial SLW in the diffusion/dendritic growth layer, suggesting a favorable scenario for cloud seeding. (2) During an airborne seeding case, seeded clouds exhibited significantly higher IWC and ice particle concentrations than unseeded clouds, with IWC up to 0.20 g m-3 and ice particles (> 400 µm) exceeding 7 L-1. Seeded clouds also showed a 30% decrease in mean liquid water content (LWC) and droplet concentrations, indicating efficient glaciation influenced by AgI. Snow developed in seeded clouds 15–40 minutes after AgI release, marked by a shift from mixed-phase clouds with SLW to ice clouds, and the lidar-measured linear depolarization ratio (LDR) increased to > 0.3. (3) The numerical experiments revealed a strong correlation between AgI concentration and ice water mass enhancement, with the most effective ice growth occurring in regions of significant AgI concentrations. Cloud seeding impact on ice initiation was efficient under conditions characterized by temperatures between -18°C and -14°C, unstable stratification (Ri < 0.25), vertical updrafts (W ̅= 0.6 m s-1), supersaturation with respect to ice (averaged Si ~1.1), sub-saturation with respect to water (averaged Sw ~0.96).</p
Aero-Thermo-Elastic Analysis and Optimization of Scramjet Inlets
Get PDFAlthough supersonic combustion ramjets -- scramjets -- provide a fuel-efficient method for propulsion at hypersonic speeds, current challenges with the engine prohibit the robustness necessary for space accessibility and trans-atmospheric flight. One such challenge the engine faces is that the inlet is a highly elongated compression surface that is prone to deformations due to the combined high thermal and structural loads. This dissertation begins by developing a high-fidelity aero-thermo-elastic model to quantify the impacts of the deformation on the inlet behavior; the model subsequently couples to a low-fidelity engine model to understand the ramifications on the downstream components and the engine as a whole. The system is found to be extremely sensitive to the changes in deformation, leading to increased flow separation and heating and to deviations of the engine performance and efficiency from the original design point. Additionally, the deformations impact the vehicle's aerodynamic performance due to the integrated airframe/inlet design. Therefore, the design of the inlet must include the implications of these deformations and to do so, an aero-thermo-elastic sensitivity analysis and optimization process are developed for this work. By leveraging high-fidelity solvers, a more accurate assessment of the fluid-thermal-structural interactions is possible; however, there is a high computational cost associated with these analyses, especially when optimizations are considered. The current implementation reduces the cost by leveraging a semi-analytical aero-thermo-elastic sensitivity analysis, which combines a direct method approach for the fluid dynamics and a finite-difference approach for the thermo-structural response. With the computationally efficient aerothermodynamic and aero-thermo-elastic sensitivity analyses in place, hypersonic optimizations are performed to redesign a re-entry vehicle and a scramjet inlet for better performance. Together, these chapters demonstrate the development and application of advanced analysis and optimization techniques to improve the performance of hypersonic vehicles, offering insights into the coupling of aerothermodynamics, thermal response, and structural deformation.</p
Chromatic Applications of Equivariant Stable Homotopy Theory
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In this dissertation, we apply computational methods in equivariant stable homotopy theory to the following question in chromatic homotopy theory: when is a higher real K-theory self-dual?. In short, this is the case in all known examples. We prove some new examples, most notably the height four higher real K-theory E hC8 4 . These equivariant techniques have their origins in the Hill– Hopkins–Ravenel solution to the Kervaire invariant one problem, a key insight of which involved constructing a computationally tractable model for E hC8 4 . We make heavy use of related models dubbed the HHR theories, and the HHR slice filtration on them to deduce our results. We also introduce a new filtration, the (G · tm)-Bockstein filtration as a complementary tool to the slice filtration for studying the HHR theories.</p
De-/Re-Queering Drag: Exploring the Roots and Imagining the Future of Gender Performance
Get PDFThe mainstreamification of drag has presented a very narrow view of what drag can be. While shows like RuPaul’s Drag Race have brought more attention to drag spaces, they have perpetuated stereotypical portrayals of drag and drag performers. We can move past this by de- and re-queering drag: that is, opening up drag to non-queer allies and people of all abilities and walks of life while simultaneously reconnecting with the roots and origins of drags and uplifting the voices of those who are systemically marginalized, even within the queer and drag communities. By doing these things, which are very interconnected, drag can become more than just the stereotypical portrayals of it and become more queer than Drag Race portrays.</p
Design, Development, Fabrication, Integration, and Analysis of the Spectroscopic Ultraviolet Multi-object Observatory (SUMO) Prototype
Get PDFThe Spectroscopic Ultraviolet Multi-object Observatory (SUMO) is a mission concept designed for small satellite platforms, built around an advanced digital micromirror device (DMD)-based spectrograph. This work covers all the phases of the first prototype design, including optical design, mechanical design, procurement of parts, fabrication, integration, controller development, preliminary laboratory testing, and proposed flight aboard the Integral Field Ultraviolet Spectroscopic Experiment (INFUSE) sounding rocket. It also details some of the ways different observation techniques can be implemented, with particular emphases on the HTSI (Hadamard Transform Spectral Imaging) technique. The SUMO Prototype is part of the technology maturation program of SUMO and will be the first time a DMD-based instrument is deployed in space. Because the SUMO Prototype will be deployed as a secondary payload, the spectrograph is designed for completely autonomous operation in the near-ultraviolet (NUV) regime. This research encapsulates a wide range of programs, including efforts to understand the processes of star formation and galaxy evolution. Since the last major UV NASA missions, FUSE and GALEX, NASA has invested significantly into technology development for the UV regime. As a result, high reflectance mirror coatings and state-of-the-art detectors are now available. These technologies, along with the developed optical design, allow SUMO to achieve effective areas that are comparable to those achieved by FUSE and GALEX, at a fraction of the size and cost. The SUMO Prototype consists of an 8 cm Cassegrain telescope and a digital micromirror device (DMD)-based multi-object spectrometer (MOS), with parallel imaging and spectroscopic channels. The SUMO Prototype is set to complete its first flight in Fall 2025 aboard the INFUSE sounding rocket.</p
High Throughput Mechanistic Modeling for Electrocatalyst Materials Discoveryfrom Climate Trends to Krill Habitat: Modeling the Physical and Biological Drivers of Antarctic Ecosystem
Get PDFThe Antarctic sea ice zone is a dynamic and rapidly changing system, where physical and biological processes shape ecosystem structure and function. Antarctic krill (Euphausia superba) are a key species in Southern Ocean ecosystems, tightly linked to the physical environment through sea ice, ocean circulation, and primary production dynamics. Using three interdisciplinary modeling approaches, this work traces the interactions between large-scale climate and sea ice dynamics to their ecological impacts on krill habitat use. First, Earth System Model simulations indicate that ongoing sea ice loss will fundamentally alter net primary productivity, with polynyas and marginal ice zones remaining crucial productivity hotspots. Second, a qualitative network model highlights regional differences in autumn productivity and sea ice cover that affect larval krill overwinter survival under future climate scenarios. The model also suggests that sea ice terraces may serve as predator refuges, an emerging hypothesis requiring further investigation. Third, integrating the descent-ascent cycle of early-stage larval krill into a regional ocean modeling system reveals how physical and biological processes shape transport pathways and retention in nursery grounds. Results suggest that connectivity between spawning and nursery areas is influenced by biological variability, particularly in early life history traits. This dissertation offers complementary insights into climate variability, sea ice dynamics, and krill ecology, providing a multi-faceted perspective on how the Antarctic marine ecosystem responds to environmental change. By linking climate-driven shifts in sea ice and ocean circulation to krill habitat use, population connectivity, and recruit�ment processes, these findings advance climate-informed ecosystem modeling and support adaptive management strategies. More broadly, this research highlights the necessity of interdisciplinary approaches for forecasting the future of Antarctic ecosystems in a rapidly changing climate.</p
For the Love of Writing: A Collaborative Pursuit Towards Humanizing Writing Experiences for Preservice Teachers
Get PDFIn response to a need for more robust opportunities for preservice teachers to interact with writing and the teaching of writing, this study explored the experiences of five preservice teachers who came together to co-design a year-long writing community centered around humanizing and loving theories and pedagogies. Drawing upon phenomenology and interpretative phenomenological analysis and humanizing and loving writing practices, this dissertation showcases the individual and collective experiences of the five preservice teachers who participated in our writing community. Represented through narratives in verse, an intentional move to highlight how dissertation writing can take unconventional shapes and forms, this study reveals three common themes that lived saliently across each of the five preservice teachers’ experiences in our writing community: Writing is influenced by past schooling experiences, writing is connected to identity, and being in community is important. These themes hold implications for how teacher educators can design humanizing and loving writing experiences for the preservice teachers they work alongside and offer opportunities for future learning and research about designing writing experiences within teacher preparation that move us towards more loving, humanizing, and justice-oriented writing experiences in education spaces.</p
God-Hole Theory
Get PDFGod-Hole Theory aligns the twelve-steps of Narcotics Anonymous with the twelve-stages of the hero’s journey. This framing underpins the movement of poems in first and third person as they are concerned with a speaker who completes a full adventure arc taking a personal, rather than physical, journey. To accomplish this arc, the speaker creates a safe house within herself as a permission to walk through the depths of her own interrogating ruminations while maintaining composure and responsibility in her outer life. She initiates her transformation by studying her reflection from varying points of view. In this private space, her sense of personal agency is strengthened as she sheds the outside expectations that once shaped her identity. Her ordinary world is mundane, day-to-day, and social. For the hero, her "special world," the landscape of her safe house, is where her journey proceeds from the “ordinary world.” Her "call to adventure" arrives amid the lifestyle and identity titles of an “ordinary world” that the speaker has normalized as her fated existence.
God-Hole means to frame the speaker as a hero grappling with change, both internal, in the self, and external, in her relationships to people, places, and things. A major theme of the manuscript centers on "repair" that is spiritual as well as physical and personal. As in most hero's narratives, even as in a fool’s journey in a tarot deck, our speaker's journey concludes in triumph and an epiphany that strength and confidence are greatest from, and had always existed, within her. While the twelve-steps and hero’s journey shape the methodology of God-Hole Theory as both thematic plot and structural framework, my choices in prosody inform the emotional impact of the work collectively. Formally, I use the sestet within the tradition of an Italian sonnet, as a vehicle toward conclusion or solution. I work within the notion six, as a "perfect" number, maintains balance in and of itself, and so, the problem to which the sestet responds, which is traditionally introduced in the octave, is absent. The "question" is silent and exists only in the past so that the manuscript is predicated on presence as opposed to absence, solution as opposed to question, response as opposed to call.</p
Machine Learning Driven Optimization of Complex Turbulent Flows
Get PDFOptimizing complex turbulent flows presents a difficult challenge due to the non-linear, chaotic nature of turbulence. Most fluid flows found in nature or in engineering applications are turbulent, prompting the need for a design optimization method that can quickly and efficiently handle this complexity. Incorporating machine learning and artificial intelligence can greatly accelerate traditionally computationally-intensive methods of optimizing these flows. The aim of this thesis is to showcase the development of a continuously-learning, machine-learning driven optimization method. This is coupled with computational fluid dynamics (CFD) and is applied to various engineering design problems to demonstrate its potential as a powerful engineering design tool.
The first case study presented is the optimization of the exit turbulence field in a gas turbine combustor simulator. Combustor turbulence in a gas turbine engine greatly influences the efficiency of the downstream high pressure turbine stage. Studies have shown that combustor turbulence can result in a 1.3% reduction in stage efficiency of the turbine. This is a staggering number when considering the impact on engine fuel efficiency, with improvements of 0.1% generally garnering substantial research funding. With an optimized design, I am able to achieve substantial improvements in stage efficiency, as well as identify the specific aspects of combustor geometry that contribute to this finding. The second case study presented is the optimization of airflow patterns in a dental office to minimize infection spread. The placement of the air supply and return vents is analyzed to produce optimal circulation within the building and decrease infection potential for dental personnel and patients.
Two more cases are presented as tutorial cases for the packaged optimizer and to expand functionality of the optimization scheme, named the Multi-fidelity Integrated Learning Optimization, or MILO. The third case is a simplified heat exchanger, where the cooling air temperature, velocity, and fan speed is adjusted to target a desired outlet water temperature. Uncertainty in the inlet conditions and fan speed is propagated throughout the optimization, showing the potential success of this tool when used in real-world industrial applications where operating conditions may vary. The fourth case introduces multi-objective optimization of a fire suppression system where both the mass flow rate of the water and the amount of solid burned are minimized. This demonstration of a multi-objective problem radically expands the number of engineering design problems that MILO can be applied to. In all cases presented in this thesis, there is a substantial improvement in design performance despite the numerous design constraints applied, as well as an average 88% savings in the number of CPU hours needed to reach an optimized solution.</p
Modular Design and Electrochemical Properties of Xanthene Based Electrochromic Materials
Get PDFElectrochromic materials that exhibit reversible color changes in response to redoxevents are of great interest for applications in smart displays, sensors, and energy-efficient devices. This thesis explores a modular approach to electrochromic system design by coupling redox-active electrophores with xanthene-based pH-indicator chromophores. The goal was to develop systems capable of clean and reversible switching between near-colorless and highly colored states while enabling tunable color control.
This research explores the modular design of electrochromic systems by investigatingthe interplay between redox-active electrophores and xanthene-based chromophores. The investigation began with the synthesis and characterization of a ferrocene-substituted rhodamine derivative, revealing that a single-electron oxidation of the ferrocene unit was insufficient to fully induce ring-opening, whereas a second oxidation significantly enhanced the color transformation. Expanding on this, the next study examines the impact of various electrophores, including p-phenylenediamine, p-julolidineamine, ferrocene hydrazone, and thioester, demonstrating how subtle modifications in redox-active groups influence electrochemical and optical properties. Subsequently, the versatility of this approach was further explored by modifying the xanthene core into rhodamine 101, fluorescein, and pyrrolebased systems. It was uncovered that stronger π-donor substituents can facilitate singleelectron oxidation-induced ring-opening, whereas weaker donors may prevent the process altogether. Together, these studies provide key insights into structure-function relationships, enabling precise control over color-switching behavior and reversibility in electrochromic materials. These insights establish a foundation for the rational design of next-generation electrochromic materials with improved performance, tunable optical properties, and enhanced reversibility. By leveraging a modular design strategy, this research paves the way for the development of high-performance color-switching materials for advanced optical applications.</p
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