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  Computational Approach to Wingtip Jets Effect on Flow Entrainment and Aerodynamics

  Hanquist, Kyle M.; Mozzone, Luciano Mario; Shkarayev, Sergey V.; Hacker, Wayne L. (The University of Arizona., 2026)

  This work presents computation analysis of the dynamics of a wing with blowing jets at the wingtip. Specifically, the project uses a NACA 0012 wing model, with internal flow chambers and blowing jet slits at the wingtip. With this wing setup, the project was a sensitivity investigation to the impact of different Computational Fluid Dynamic setup conditions and meshes across a range of different freestream velocities and jet pressures. This computational study complements an experimental investigation of the same NACA 0012 with wingtip jets. A comparison of the experimental and computational results are discussed, with a focus on the similarities and differences. The study found the impact of blowing jets, either from the top or bottom jet, had positive effects to coefficient of lift by artificially extending out the wings aspect ratio, and interrupting the formation of wingtip vortices. It was also observed that the inclusion of jets has a more significant impact at lower freestream velocities, where the difference between jet pressure and freestream velocity is larger. Lastly, these results can be correlated back to the experimental data, giving credence to the benefits of wingtip jets. The results will discuss these findings in more detail, assessing the impact of freestream velocity, jet velocity, solver, turbulence model, mesh, and whether the top, bottom, or no jet was active.
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  A New Algorithm for the Open-Pit Production Scheduling Optimization Problem

  Anani, Angelina; Leiterman, Isaac; Anani, Angelina; Risso, Nathalie; Momayez, Moe (The University of Arizona., 2026)

  Open-pit mine production scheduling optimization is pivotal in ensuring a mine operates profitably. However, achieving optimality in a production schedule is often intractable. This is due to two factors. The first is the NP-hard classification of the problem, meaning there are no known efficient algorithms for finding exact solutions. The second is the large scale of realistic block models, which can lead to millions of variables and constraints with which the optimization problem is subject to. Therefore, it is common practice to rely on heuristics and block aggregation methods for generating operationally feasible solutions. However, these solutions are not guaranteed to be optimal and are more often than not far from optimality. This research presents an alternative for gathering optimal and near-optimal solutions through a novel relaxation-repair algorithm. Precedence constraints, which make up the majority of the constraints present in an open-pit production scheduling optimization problem, represent open-pit slope stability. However, due to how they are enforced, each is implied by the other precedence constraints when the full precedence set is considered. Because of this, the constraint matrix size is inflated, and the solver’s performance decreases. The goal of this research is to showcase a method for applying only subsets of precedence constraints instead of the full precedence set. The initial relaxation phase of the algorithm solves, to optimality, the problem with only a subset of the precedence constraints. However, the relaxation is not assured to be operationally feasible with respect to the full precedence set. Therefore, a final repair phase is conducted to recover feasibility. Some instances were able to achieve optimality without requiring a repair step. Through testing, this algorithm has shown that it can outperform a traditional precedence formulation in several instances. In some cases, the algorithm generated optimal and near-optimal (<0.15% optimality gap) production schedules in under a quarter of the time.
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  Zernike Sensitivty Based Machine Learning Aided Optical Alignment

  Kim, Daewook; May, Jeffrey; Sasian, Jose; Choi, Heejoo (The University of Arizona., 2026)

  The science of telescope alignment is a puzzle to solve what compensator and degree(s) of freedom (DOF) to use and how far it needs to move to achieve the goal of minimizing the total wavefront error. How far the compensator needs to move is determined by an optimizer such as Zernike sensitivity analysis, which solves a system of linear equations to determine an alignment solution1. The alignment solution, as determined by the optimizer, is only as good as the compensator selection allows it to be. This represents a classic case of bad in, bad out. Traditionally, the choice of compensator comes from an understanding of the Zernike sensitivities and selecting the compensator that is most sensitive to the Zernike term that is to be minimized. This approach alone can be challenging to determine the absolute best set of compensators to use to minimize the wavefront error while also minimizing the number of alignment iterations and the number of compensators used. Implementing a trained machine learning neural network algorithm to aid in compensator selection will result in a reduction in alignment iterations to achieve a minimized solution. Any of three training methodologies can be used in the aid of optical alignment, the three methods are all based on the design specific Zernike sensitivities. The methods are Field Variation, Local Sensitivity, and Global Sensitivity. All methods, without human involvement, will align to a global minimum in less alignment iterations than a trained human. With a trained human who understands Zernike sensitivities and how they can be used to select compensators, all three methods will result in a reduction in compensators use to achieve the global minimum in less alignment iterations.
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  Evaluation of Spatial Light Modulator for High Contrast Imaging

  Guyon, Olivier; Bragg, Jennifer; Douglas, Ewan S.; Males, Jared R. (The University of Arizona., 2025)

  High Contrast Imaging (HCI) systems are optimized to image faint objects located near bright point sources. This is essential to exoplanet imaging and the search for biological activity by spectroscopic characterization of exoplanet atmospheres. HCI systems for future large space telescopes capable of imaging about a dozen habitable exoplanets will require correction of >10,000 wavefront modes, but conventional Deformable Mirrors (DMs) only provide about 3,000 actuators. DMs that have ? 128×128 actuators are required by these upcoming projects, as identified in the 2019 NASA Exoplanet Exploration Program Technology Gap List1. A Spatial Light Modulator (SLM) can offer more actuators (about 2 x 106 actuators) than a conventional DM. SLMs can also offer a compact solution to this large-format DM challenge. Thanks to recent advances, SLMs can now offer both the actuator count and control speed (.7 kHz) required for exoplanet imaging for both ground and space telescopes. It is envisioned that existing SLMs could one day serve as a second-order correction after a first coarse correction using a conventional DM. While SLMs offer a promising solution to the large-format DM’s actuator count challenge, they have not yet been used in high contrast imaging correction in broadband light, and their stability, polarization, and chromaticity must be better understood and accounted for. In this thesis work, an SLM device was characterized and validated in the lab for use in HCI, measuring its contrast stability, polarization cross-talk, and chromaticity in the lab.
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  Synergy Between Natural Antimicrobials Against Eschericha coli Bacteriophages

  Gerba, Charles P.; Sanchez, Ray Luther; Bright, Kelly R.; Ikner, Luisa (The University of Arizona., 2025)

  Household and industrial disinfectants are often used without consideration of their fate and transport after use. Disinfectant products are well known for their convenience and efficiency. However, they can potentially create hazardous chemical byproducts ranging from carcinogens to ecological degradation. To minimize these effects, alternative methods of sanitation using naturally occurring antimicrobials have been proposed and developed. These antimicrobials include complex organic molecules, essential oils (EOs), and inorganic acids. This research focused on organic acids and essential oils from various plant species that have been demonstrated in previous studies to have antiviral, antifungal, and antibacterial properties. To determine the effectiveness and possible synergy between combinations of these natural products, a series of experiments targeting bacteriophages with three different capsid and genomic characteristics were conducted including MS2 (ssRNA icosahedral), ?X174 (ssDNA icosahedral) and PR772 (dsDNA icosahedral with encapsulating membrane) bacteriophages with Escherichia coli hosts. The greatest degree of synergy for the substances tested was observed for several antimicrobial combinations against MS2 and PR772. Citric acid (1.0%) paired with either cinnamaldehyde (1.0%-3.0%) or carvacrol (0.1%-0.5%) had the greatest synergy and effectiveness against both MS2 and PR772 (increase in efficacy ranging from 0.80 to >3.42 log greater reductions than an additive effect). ?X174 was more resistant to most antimicrobials than both PR772 and MS2, and exhibited little synergy with most antimicrobial combinations, possibly because of its stable circular genome; however, several combinations were found with moderate yet significant synergistic increases in efficacy of 0.27 to 0.50 log greater reductions than an additive effect. The combination of carvacrol with cinnamaldehyde was the least effective with antagonism observed against PR772 and a likely only additive effect against the other two viruses, possibly due to the competition of both antimicrobials for the same site on the viral genome. Finding synergy as opposed to additive effects is important for reducing the volume of products used for sanitation.
• MULTISPECTRAL WIDE FIELD OF VIEW REFLECTIVE COLLIMATOR

  Sasián, José; Liang, Rongguang; Mitchell, Bradley Alan; Koshkin, Ilya (The University of Arizona., 2025)

  Wide field-of-view (WFOV) imaging systems are increasingly essential in modern optical applications such as autonomous navigation, remote sensing, and machine vision. However, their characterization and calibration require collimator systems capable of delivering high-quality, uniform, and spectrally broad illumination across large angular extents. This thesis presents the background on collimators, current solutions, and proposed multi-spectral reflective collimator system optimized for WFOV testing. The system employs an off-axis reflective architecture to eliminate chromatic aberrations inherent in refractive designs while maintaining diffraction-limited performance across visible to long infrared wavelengths. A custom optical configuration was developed to balance field uniformity, wavefront error, and manufacturability enabling precise alignment and repeatable test conditions for wide-angle sensors. The resulting collimator achieves high wavefront quality and spectral neutrality over an extended field. It offers a practical, high-performance solution for industrial and research environments. This work demonstrates a manufacturable approach that supports emerging needs in multi-spectral imaging and calibration of next-generation optical instruments.
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  Small Mammals Along Elevational Gradients & Ground-Dwelling Arthropods Along Red Squirrel Midden Residency Gradients, Pinaleño Mountains, Arizona

  Pasch, Bret; Tierney, Ellen Reed; Bledsoe, Ellen; Steidl, Robert (The University of Arizona., 2026)

  Ecosystem stability is important for threatened biomes such as the Madrean Archipelago that harbor endemic species of conservation concern. Small mammals play key ecological roles that influence ecosystem function (e.g. homeostasis, or how ecosystem structure remains constant in response to disturbances), yet knowledge of their distributions and interactions is lacking in the region. In my first study, I documented richness and abundance patterns of small mammals along an elevation gradient in the Pinaleño Mountains, the most prominent mountain range of the Madrean Archipelago. I found that species richness peaked in the semi-desert grassland and mixed conifer life zones, but the life zone with the greatest abundance varied seasonally. The study provides insight into factors influencing elevational distributions and serves as a baseline to incorporate monitoring of small mammals as indicators of environmental change. My second study investigated how endangered Mt. Graham red squirrel (Tamiasciurus fremonti grahamensis) middens (cone scale piles where squirrels larderhoard food) influenced the community of ground-dwelling arthropods across a gradient of residency history. I found that middens that had longer squirrel residencies (squirrels residing at and maintaining the midden for longer time periods) were associated with more arthropods compared to lower residency middens. However, the diversity of ground-dwelling arthropods relative to squirrel residency history depended on the diversity metric used. Monitoring of arthropod communities within middens can provide a novel method to assess temporal changes in squirrel food-caching strategies and evaluate forest management actions that may influence midden conditions. Collectively, studying small mammal interactions across diverse gradients can identify new ways of seeing and responding to disturbances that the region may experience in the future.
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  Russo-Ukrainian War through the Lens of Serhiy Zhadan's War Diary

  Gordienko, Anastasia; Czerkawski, Betül C.; Jens, Benjamin; Thompson, Suzanne (The University of Arizona., 2025)

  In early 2022, when the Russian Federation launched a full-scale invasion of its neighboring country, Ukraine, Ukrainian writers used their pens to convey their everyday experiences under Russia’s continuous attacks. While other literary forms, such as novels, poetry, and plays, were written about the war, the diary emerged as a notable genre. The primary purpose of this study is to explore the style, content, and form in Zhadan's diary. Scholarly literature on diaries as a form of literary and historical documentation, such as Yanina Kulinska and Bruce Merry's works on war diaries, provides background for the study, which focuses on diary entries describing the daily experiences of ordinary Ukrainians during a period of national suffering. Although this study focuses on a single work by a single author, Serhiy Zhadan, the findings can nevertheless be extrapolated to illuminate a new generation of Ukrainian writers and the general themes that resonate with them, particularly their interpretation of Russia’s second invasion of Ukraine. By situating Zhadan’s work within the broader tradition of wartime diaries, the study highlights the interplay between the author's personal testimony and the collective memory of Ukrainians. It highlights how Zhadan's individual reflections not only document his lived experiences but also help form a national narrative. In doing so, the diary becomes both a literary artifact and a historical document, bridging the gap between private suffering and national identity.
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  Surveying the Growth of a Mycenaean State: A Reassessment of Pylian Expansion in Late Bronze Age Messenia

  Schon, Robert; Jones, Sawyer Jeremy; Blake, Emma; Stephan, Robert (The University of Arizona., 2026)

  This thesis reassesses the nature and timeline of the expansion of the Kingdom of Pylos in Messenia during the Late Bronze Age. Evidence from Linear B documents, excavations, and regional survey projects has provided substantial information about the administration and economy of the Pylian state during the height of its power at the end of the LH IIIB period, but the nature and timeline of its growth from a single settlement to the palatial capital of Messenia is not as fully understood. Messenian survey data are used here to catalogue, map, and analyze Mycenaean settlements in the region for the LH I-II, LH IIIA-B, and LH IIIC periods. Changes to settlement patterns that are indicative of Pylian expansion are identified through a combination of traditional and novel methods. These changes are then considered along regional lines, from which three distinct waves of Pylian expansion in Messenia during the Late Bronze Age are shown.
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  From Catch to Canvas: An Analysis of the Archaeofaunal Record of Minoan Sites and Symbolic Marine Iconography

  Schon, Robert R.; Parks, Elizabeth Nelson; Romano, David D.; Stephan, Robert R. (The University of Arizona., 2026)

  The Southern Aegean generally features oligotrophic waters punctuated by highly productivemicro-environments such as ravine estuaries and coastal lagoons. These ecological conditions support the multi-species environments that define the coastal fisheries of Akrotiri, Palaikastro, Mochlos, Pseira, and Kommos. The study analyzes of ichthyofaunal assemblages to identify the types of fish Minoan people caught, processed, and consumed at each site and to compare the assemblages across sites in order to distinguish any patterns that may indicate preference or unique circumstances. This analysis also compares these assemblages with modern Greek commercial fishing statistics to explore the long-term continuities and inconsistencies in fishing practices. The results demonstrate a strong preference for inshore fishing, as assemblages consist largely of small, demersal species, particularly the Sparidae and Centracanthidae families. Fishers occasionally targeted larger, pelagic species offshore, although they did so far less frequently. Minoan iconography reveals a distinct fascination with the marine environment and the animals that inhabited it. Despite the frequent depiction of sea creatures in Minoan art, the species people consumed rarely overlap with those represented iconographically. Instead, the Minoans appear to focus on the dolphin, a sea creature absent from the faunal assemblages, as their ‘key species’. Other fish appear only rarely or in vague forms within the iconographic record. These discrepancies suggest that the Minoans emphasized symbolic and visually striking marine animals, as opposed to those that formed their diet. The widespread occurrence of similar taxa across settlements suggests that multiple social strata commonly consumed fish rather than restricted by status, although certain contexts point to feasting events. Comparisons between ichthyofaunal data and marine iconography further demonstrate limited overlap in species representation. Everyday diets relied on small, reliable coastal fish, while Minoan visual culture highlighted pelagic species that symbolized the open ocean and the Minoan sea-faring identity. This divergence underscores the economic and cultural importance of the sea in Minoan society beyond subsistence.
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  Genetic Diversity and Connectivity of Lowland Leopard Frogs (Lithobates Yavapaiensis) in Southeastern Arizona

  Rick, Jessica; Bauder, Javan; Hasl, Beth; Vargas, Karla; Bogan, Michael (The University of Arizona., 2025)

  Aquatic habitats in arid landscapes are critical for biodiversity but are increasingly imperiled by habitat fragmentation and hydrological alteration. Amphibians in these environments are especially vulnerable due to their reliance on aquatic habitats that are separated by inhospitable terrain. The lowland leopard frog (Lithobates yavapaiensis), once widely distributed across the southwestern United States, has undergone substantial range reductions and is now largely confined to perennial aquatic systems. Despite being a species of conservation concern, little is known about its population structure or connectivity in southeastern Arizona. We used genome-wide single nucleotide polymorphism (SNP) data from double-digest restriction site-association DNA sequencing (ddRADseq) to investigate genetic diversity, population structure, and landscape genetics. We analyzed 492 individuals from 33 sites for population structure and 421 individuals from 29 sites for landscape genetic analyses. Genetic diversity was uniformly low across sites, consistent with small and isolated populations. Strong hierarchical genetic structure corresponded to five major geographic regions: Cienega Creek, Rincon Mountains, Catalina Mountains, Galiuro Mountains, and the San Pedro River Basin. Within regions, sites were genetically similar, consistent with dispersal along hydrological networks, whereas differentiation among regions indicated restricted gene flow across broader spatial scales. Genetic similarity declined sharply beyond approximately 10 km, and spatial analyses revealed that landscape features strongly influenced connectivity. Topographic position and solar exposure explained patterns of gene flow better than geographic distance alone, with valleys and shaded slopes facilitating movement while ridge-like and sun-exposed areas limited connectivity. Together, these results show that L. yavapaiensis populations are structured by both regional genetic differentiation and landscape heterogeneity. Conserving hydrological connectivity and low-resistance topographic and thermal corridors will be essential to maintain gene flow and support long-term population persistence in southeastern Arizona.
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  Power Side-Channel Leakage Assessment of FPGA-Based Spiking Neural Networks

  Salehi, Soheil; Pugazhenthi, Veeramani; Satam, Pratik; Dass, Jyotikrishna (The University of Arizona., 2025)

  On-chip learning refers to the process of training or updating machine learning models directly on specialized hardware, rather than relying on external computational resources such as CPUs or GPUs. On-chip learning offers reduced latency, energy efficiency, privacy, and adaptability. Hence, on-chip learning is a promising approach for enabling intelligent decision-making and adaptability in edge and IoT devices while addressing the challenges posed by limited resources and data privacy concerns. One of the main features of on-chip learning involves adapting synaptic weights within a Spiking Neural Network (SNN), allowing dynamic adjustments of the network's behavior to align with desired outcomes. Such adaptability is a double-edged sword, as it opens doors for potential security vulnerabilities. Unaddressed security risks in on-chip learning could lead to a wide range of threats, including data leaks, unauthorized access, and even adversarial manipulation of the learning process. In this work, we demonstrate a successful power side-channel attack (SCA) targeting a quantized SNN deployed on the CW305 FPGA using ChipWhisperer. Our analysis reveals consistent power leakage patterns correlated with neuron updates, enabling attackers to infer internal model attributes without accessing model weights or inputs. Furthermore, we extend this analysis by performing a Correlation Power Analysis (CPA) attack to successfully recover the secret synaptic weights of the network. Using a Hamming Weight leakage model, we demonstrate that these weights can be extracted with high confidence using as few as 1500 power traces. This thesis aims to provide a comprehensive overview of the security risks associated with on-chip learning, highlighting the potential vulnerabilities within the SNN architecture. We will examine real-world scenarios in which these vulnerabilities can be exploited and discuss their implications for applications in IoT, edge computing, and other domains. Furthermore, this thesis will outline safeguards and mitigation strategies to address these security concerns at the software-hardware boundary. We will explore design principles, cryptographic techniques, and access control mechanisms that can be used to secure on-chip learning systems without impacting their performance.
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  Where’s My Sister? The Experience of Ambiguous Loss in Native American Communities with Missing Native American People

  O'Connor, Mary-Frances; Pino, Yvette; Sbarra, David; Sullivan, Daniel (The University of Arizona., 2025)

  In 2016, 5712 Native American women went missing in 2016 alone, which is considered to be a low estimate due to complex jurisdiction issues and inaccurate missing person’s databases. Often these cases go unsolved for years, if they are solved at all, which can lead to many Indigenous people experiencing ambiguous loss. Ambiguous loss is the experience of uncertainty of whether a loved one will return, and closure remains unobtainable. Loved ones who are experiencing ambiguous loss are left hoping that their loved one is alive, which may draw out the grieving process, further exacerbating these health disparities. The present study is a national online survey that was distributed to a wide sample of Native Americans (n=234), in order to reflect the diversity that exists in the many tribes and Indigenous groups that exist in the US. The survey included questionnaires assessing ambiguous loss using the Ambiguous Loss Inventory + (ALI+), grief, depression, trauma symptoms, and enculturation. Analyses were conducted in R Studio, and a regression indicated that for those with a missing loved one had higher grief severity than those with a death-related loss. A regression also indicated that the ambiguous loss group also had higher depression and trauma symptoms than the death-related loss group and the group with no loss. Finally, the moderation analysis did not show significant moderation of enculturation on the relationship between loss group and grief severity. Indigenous communities must be allowed the opportunity to practice traditional ceremonies that promote healing and closure, while also increasing awareness for this issue.
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  A Quality Improvement Project of Behavioral and Family Dynamic Changes of Children and Adults With Autism That Use Home Photobiomodulation Devices

  Celaya, Melisa P.; Larson, Samuel; Lee-Iannotti, Joyce; Garcia-Filion, Pamela C. (The University of Arizona., 2025)

  Background: Autism Spectrum Disorder (ASD) affects approximately 1 in 36 children in the United States. Core features include deficits in social communication, repetitive behaviors, and associated comorbidities such as irritability, aggression, and sleep disturbances. Neuroinflammation and immune dysregulation are increasingly recognized as contributing factors in ASD pathophysiology. Transcranial photobiomodulation (tPBM), a non-invasive neuromodulation technique utilizing red and near-infrared light, has demonstrated neuroprotective, anti-inflammatory, and cognitive benefits in several neurological conditions. Preliminary evidence suggests potential therapeutic effects of tPBM in ASD.Objective: This study analyzed collected survey data from parents of adolescents and young adults with ASD who participated in at-home, self-guided sessions using twice-daily ProNeuroLIGHT transcranial and abdominal photobiomodulation therapy. The goal was to examine trends, patterns, and potential impacts of the intervention on non-compliant behaviors and parental stress, with secondary consideration of sleep quality. Methods: Twenty-one participants aged 5–34 years (mean age 11.7; 15 males, 6 females) from Latin America origin who used infrared/red LED head caps and abdominal wraps twice daily for 20 minutes. Parents completed validated Spanish versions of the Home Situation Questionnaire–ASD (HSQ-ASD) and Autism Parenting Stress Index (APSI) at baseline and follow-ups. Paired t-tests, Wilcoxon tests, and mixed-model analyses were performed to assess changes over time, with significance set at p < 0.05. Results: Statistically significant improvements were observed from baseline to both follow-up points. By the final follow-up (mean 129 days), HSQ total scores decreased by 32.7 points (p < 0.0001), HSQ mean severity scores by 1.4 (p < 0.0001), SI and DS subscale scores by 15.8 and 16.9 (p = 0.0009 and < 0.0001, respectively), and APSI scores by 13.5 (p < 0.0001). Mixed-model regression confirmed consistent daily reductions across all measures. Neither age nor sex showed significant effects. Discussion: Results indicate that combined transcranial and abdominal PBM was associated with significant reductions in non-compliant behavior and parental stress. Potential mechanisms may include modulation of neuroinflammation, improvement of gut microbiome balance, and enhancement of glymphatic clearance systems often disrupted in ASD. Conclusion: Transcranial and abdominal photobiomodulation appears to be a safe, well-tolerated, and promising non-invasive intervention for reducing behavioral challenges and caregiver stress in the ASD population that participated. Further large-scale, controlled trials are warranted to confirm efficacy, establish standardized treatment parameters, and explore underlying physiological mechanisms.
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  Optimization of Additively Manufactured Wind Turbine Blades

  Missoum, Samy; Pimienta, Isaac; Hazeli, Kavan; Li, Peiwen (The University of Arizona., 2025)

  Energy production in wind turbines can be increased in three main ways: lengthening the blades, accessing high wind speeds, and optimizing turbine efficiency. Increasing the blade length has been a common way to substantially increase wind turbine energy production. However, this trend of longer blades has led to many challenges, in particular, structural challenges from larger deflections, logistical challenges from transportation difficulty, and manufacturing challenges from the lack of specialized manufacturing warehouses.Additive manufacturing (AM) has shown promise in addressing some of these challenges by enabling complex, optimal geometries, simplifying manufacturing, and increasing accessibility by printing the blades on site. In order to leverage AM, this thesis investigates the use of computational optimization, in particular multi-objective optimization, to balance competing objectives as a means to determine the optimal design of wind turbine blades. The optimal design will be a compromise between annual energy production (AEP) and various structural performance metrics. This goal is achieved by first investigating two AM feasible internal structures, lattice-based and topology optimized designs. These two designs are compared across key performance metrics, including compliance and natural frequency. The topology optimized design demonstrates superior performance and is selected for a full multi-objective blade optimization. This multi-objective optimization is performed to maximize both the annual energy production and first natural frequency. The performances of the resulting optimal designs are then quantified through comparison to an existing optimal composite wind turbine blade. Overall, the findings highlight the potential of optimization-driven additively manufactured blade design.
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  Study of the Intrinsic Stochasticity in 1T-TaS? Charge-Density-Wave Oscillator Based Neuron for Combinatorial Optimization

  Yan, Xiaodong; Xin, Jianyu; Yan, Xiaodong; Kim, Brian; Latypov, Marat (The University of Arizona., 2025)

  Biological neurons often exhibit stochastic firing behavior, which plays an important role in adaptive computation and information processing. Inspired by this behavior, this study investigates the stochastic firing characteristics of 1T-TaS?-based artificial neurons and their application to combinatorial optimization problems, specifically the traveling salesman problem (TSP). Although various algorithms have been proposed to solve the TSP, they often become trapped in local optima, partly due to the limitations of software-based pseudorandom number generators. Hardware-based true randomness provides a promising means to overcome this limitation.Among hardware true random generators, artificial stochastic neurons based on charge density wave (CDW) materials represent an emerging and largely unexplored direction, with 1T-TaS? being particularly noteworthy. At room temperature, 1T-TaS? undergoes CDW phase transitions which induce oscillatory behavior exhibiting stochasticity. In this work, a Pearson-Anson oscillator circuit incorporating a two-terminal 1T-TaS? device, a parallel capacitor, and a series resistor was designed to construct a hardware stochastic neuron. The firing rate-voltage (f-V) relationship of the device was measured, revealing randomly shifted curves that follow a power-law distribution, with the slope influenced by the series resistance. In this study, two kinds of intrinsic stochastic behaviors were identified. One is capacitance-driven, in which the noise in the f-V curve shows a positive correlation with the capacitance. The other is caused by random threshold-voltage fluctuations, leading to stochastic shifts of the f-V curve along the voltage axis. Based on the experimentally observed power-law stochasticity, the pseudorandom number generation component of a particle swarm optimization (PSO) algorithm was replaced with hardware-derived true randomness. The modified PSO was evaluated on TSP instances with 100 randomly generated cities. The results demonstrated that the PSO with hardware-derived true randomness required fewer iterations and generally produced shorter route solutions compared to the standard PSO. This work reveals the potential of CDW-material-based artificial stochastic neurons for hardware acceleration in combinatorial optimization, laying the groundwork for the development of high-efficiency and fast random hardware accelerators.
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  Tracing Eight Years of Kuwait’s Air Quality Trends From Traffic, Industry, and Dust

  Arellano, Avelino; Mohammad, Ahmad; Arellano, Avelino; Sorooshian, Armin; Robinson, Ellis (The University of Arizona., 2025)

  Rapid urbanization, industrial expansion, and frequent dust storms have made air quality a growing concern in Kuwait, yet long-term assessments remain limited. This study provides a multi-platform evaluation of Kuwait’s air quality and emission trends from 2015 to 2022 by combining in-situ observations from the Kuwait Environmental Public Authority (K-EPA) with satellite retrievals from the Tropospheric Monitoring Instrument (TROPOMI), the Moderate Resolution Imaging Spectroradiometer (MODIS), and anthropogenic emission inventories from the Emission Database for Global Atmospheric Research (EDGAR). Our assessment allows for the identification of multi-species trends for insights into recent drivers of Kuwait’s air quality. Eight key pollutants were examined, including nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), methane (CH4), ammonia (NH3), ozone (O3), and particulate matter (PM2.5, PM10), across four sites, Shuwaikh, Ahmadi, Jahra, and Salam, each characterized by distinct industrial and residential emission profiles. Meteorological parameters such as temperature, wind speed, wind direction, and humidity were also analyzed to support the overall interpretation of the air quality trends. Results reveal clear spatiotemporal variations across Kuwait, with both industrial and residential sites showing strong positive CO-NO2 correlations (r = 0.41-0.64), indicating dominant combustion-related emissions. Mean PM2.5 (PM10) concentrations exceeded the WHO 24-hour guideline on over 73% (90%) of monitoring days. Shuwaikh emerged as the primary hotspot for NO2, CO, SO2, and CH4, while Ahmadi showed persistently elevated SO2 and CH4 linked to refineries. This integrated satellite-ground approach provides baseline trends of Kuwait’s air quality in the recent decade. While moderate decline was observed in combustion pollutants, persistently high PM2.5, PM10, CH4, and NH3 levels highlight the continued impact of industrial and dust emissions, emphasizing the need for stronger emission-control measures.
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  Microstructural and Mechanical Properties of Sulfur Cement for Lunar Applications

  Kim, Hee-Jeong; Kundu, Tribikram; Pederson, Federico Peralta; Potter, Barrett; Latypov, Marat (The University of Arizona., 2025)

  Lunar exploration has been a major topic in the US with the expansion of private space launch companies and a growing space race with the PRC. As a part of this interest in return to the moon, there has been a push to construct semi-permanent launching point or structures for future missions deeper into the solar system on the lunar surface. To accomplish this, new construction materials are required that maintain high mechanical performance while exposed to the harsh thermal, vacuum, and radiation environment of the moon. Elemental sulfur mixed with the lunar regolith to form a regolith-based sulfur cement (RSC) has been proposed to be a good solution to this problem, as it gives high strength while only using components available on the lunar surface. Additionally, the material can be reinforced by common glass fibers due to the low alkaline content of the binder. To assist with the planning of Lunar missions and give structural designers a starting point to develop infrastructure, a finite element (FE) model of structures made of RSC is required. This project measured the necessary mechanical properties to construct a FE model of the RSC structure with and without glass fiber addition. For this testing volcanic basalt soil, provided by the Biosphere 2, was used as a simulant of regolith and paired with commercial elemental sulfur. An optimum mix design was determined to be 35% sulfur and 0.5% fiber by weight of sulfur using direct compressive and tensile testing. The mechanical testing results were then applied to a FE model of a simple lunar structure using Abaqus and found to be suitable for static applications. The optimum mix was then characterized using Raman spectroscopy and XRD to measure secondary side reactions that may have occurred during the melting and casting steps. Lastly the non-destructive evaluation technique of sideband peak counting-index was applied to the material and found to be a good predictor of the sample strength.
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  Effects of Biological Soil Crusts on Surficial Processes in Sandy Soils of a Pinyon and Juniper Woodland, Colorado Plateau, USA

  Hu, Jia; Phelps, Erin L.; Mitchell, Rachel; Rutherford, William; Williams, Christopher Jason (The University of Arizona., 2025)

  Biological soil crusts (biocrusts) are widespread in dryland ecosystems, where they play a critical role in shaping surficial properties and processes. In the western United States, pinyon and juniper (PJ) woodlands have been expanding substantially, altering ecosystem structure and function. PJ trees have a competitive advantage over understory herbaceous cover, leading to increased areas of bare soil that are hydrologically vulnerable. Within PJ woodlands, biocrust often colonize the bare soil patches, modifying soil properties and influencing surficial hydrologic processes. Studies have reported mixed findings on the influence of biocrusts on runoff and erosion across landscapes. Managing practices aimed at controlling PJ encroached woodlands may inadvertently disturb biocrust communities, minimizing any benefits they provide, such as soil stability. This study conducted a suite of ground cover, soil, hydrology, and erosion experiments at the fine spatial scale (0.5 m2 plots) to quantify how varying successional stages or levels of development of biocrusts influence soil properties and surface hydrology processes in non-vegetative patches. Infiltration and runoff are largely controlled by soil aggregate stability, ground surface roughness, and percent dark cyanobacteria ground cover. In this study, non-vegetated patches dominated by late successional dark cyanobacteria biocrust exhibited greater soil stability and a rougher soil surface than patches dominated by early successional light cyanobacteria biocrust. Rainfall simulation experiments (100 mm ? h-1, 45 min) conducted on dry soil generated greater runoff and erosion from areas covered with early succession biocrusts (25 mm ? h-1 and 153 g ? m-2) relative to those covered with late succession biocrusts (11 mm ? h-1 and 24 g ? m-2). Our results suggest non-vegetated patches with early successional biocrust are more hydrologically vulnerable than those with late succession biocrust. Results from this study provide land managers and scientists valuable insight regarding ecohydrologic functioning of PJ systems with extensive biocrust ground cover and provide context and data for predicting how these ecosystems may respond to biocrust disturbances caused by natural events or management actions.
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  Characterizing the Effects of Short-Chain Fatty Acids on Campylobacter jejuni Virulence

  Vedantam, Gayatri; Rodriguez, Dominic John; Vedantam, Gayatri; Cooper, Kerry; Ravishankar, Sadhana (The University of Arizona., 2025)

  Campylobacter jejuni is the leading cause of gastroenteritis worldwide, responsible for approximately 550 million cases annually. Infection can lead to either watery or bloody/inflammatory diarrhea, depending on the severity of the disease and geographic location. Beyond acute illness, C. jejuni is linked to several post-infectious sequelae, including Guillain-Barré syndrome, reactive arthritis, and growth stunting in children. However, little is known about how intestinal metabolites such as short-chain fatty acids (SCFAs) influence C. jejuni pathogenesis. Previous studies have shown that SCFAs produced by commensal gut bacteria can modulate the virulence mechanisms of other Gram-negative enteric pathogens; however, their effects on C. jejuni remain largely unexplored. To assess this gap, this study examined the effects of three predominant intestinal SCFAs, butyrate, propionate, and acetate, at two different concentrations on ten different C. jejuni strains representing distinct sources and diarrheal phenotypes. In vitro assays were conducted to assess impacts on bacterial growth, attachment, and invasion of intestinal epithelial cells. Our results indicate that fluctuations in intestinal SCFA levels may influence critical aspects of C. jejuni pathogenesis, specifically generation time, attachment, and invasion capabilities. Results also reveal significant strain-to-strain variability, as individual strains used in this study exhibited distinct reactions and phenotypic outcomes to each SCFA treatment. Low concentrations of SCFA treatment showed a substantial impact on generation time and attachment, while no significant impact was observed on invasion capabilities. Furthermore, this study did not identify differences in phenotypic outcome based on diarrheal manifestation, consistent with previous reported findings using these same strains. These findings suggest that SCFAs may also influence gene expression, an effect that warrants further investigation in future studies. Overall, these findings suggest that individual differences in intestinal SCFA levels can modulate C. jejuni virulence and may help explain variability in severity based on diet, microbiota composition, and lifestyle factors.

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