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Description
This dissertation explores the design, testing, and implementation of cutting-edge spaceborne instrumentation through the investigation of three distinct projects: SPARCS, STRUVE, and EXCITE. The SPARCS astrophysics project focuses on the development of a thermal vacuum chamber for testing contamination-sensitive hardware, alongside the design of ground support equipment (GSE) tailored to SPARCS' performance requirements. STRUVE, a heliophysics CubeSat mission concept, is examined for its mechanical and thermal design strategies, as well as thermal sensitivity studies crucial for mission success. The EXCITE project, an infrared spectrometer balloon-based astrophysics mission, is analyzed for its opto-mechanical design and comprehensive coefficient of thermal expansion (CTE) stress analysis. Throughout the dissertation, each project's challenges, innovations, and solutions are meticulously documented, providing insights into the intricacies and demands of space instrumentation design and testing. The introduction sets the stage by contextualizing the significance of spaceborne instrumentation projects and outlining the scope of the dissertation. The chapters present detailed examinations of SPARCS, STRUVE, and EXCITE, and discuss the engineering complexities and advancements achieved in each project. In conclusion, the dissertation reflects on the lessons learned, implications for future space missions, and the broader impact of SPARCS, STRUVE, and EXCITE on the field of spaceborne instrumentation. This research contributes to the ongoing discourse surrounding space technology innovation and underscores the importance of interdisciplinary collaboration in pushing the boundaries of space exploration.
ContributorsGamaunt, Johnathan (Author) / Scowen, Paul (Thesis advisor) / Butler, Nathaniel (Thesis advisor) / de Wijn, Alfred (Committee member) / Groppi, Christopher (Committee member) / Jacobs, Daniel (Committee member) / Arizona State University (Publisher)
Created2024
Description
Encouraging women’s pursuit and retention in higher education has been an important movement in the United States over the last several decades. While there has been considerable progress, women are still underrepresented in fields related to Science, Technology, Engineering, and Mathematics (STEM). The most significant gender gap being engineering, where women make up only 21% of all engineering majors. Lack of self-efficacy is one variable that has been implicated as a barrier for women in engineering, due to implicit and explicit biases and discrimination women experience relating to engineering in higher education. Self-compassion has been shown to be strongly correlated with self-efficacy, with explanations theorized at the level of each positive subcomponent: self-kindness, common humanity, and mindfulness. The current study investigates the effects of a self-compassion mindstate induction (SCMI) intervention on engineering self-efficacy compared to a control group. This study also explores gender and race discrimination from faculty and peers in the participants' environment to observe if this plays a role in the effect of the intervention. Women (N = 73) majoring in engineering were recruited from a large southwestern university to participate. A multivariate analysis of covariance (MANCOVA) was conducted, revealing a significant three-way interaction for condition type (SCMI or control), discrimination scores, and engineering self-efficacy from Time 1 to Time 2 (F(1, 69) = 6.51, p = .01). The results of this study suggest that participants in the SCMI condition experienced a significant increase in engineering self-efficacy from Time 1 to Time 2 when controlling for discrimination in the women's environment. Self-compassion based interventions that have the potential to increase engineering self-efficacy may be particularly helpful to women who experience more gender and race discrimination in their environment. Future work should be done to examine discrimination more directly in the context of self-compassion and engineering self-efficacy. These results show promise for using brief, accessible, cost-free, positive psychology interventions to support women pursuing engineering in higher education. This research contributes to the literature aiming to address gender disparities in engineering higher education, laying the groundwork for future interventions that support underrepresented populations in STEM.
ContributorsKampf, Taylor (Author) / Lum, Heather (Thesis advisor) / Roscoe, Rod (Committee member) / Lauer, Claire (Committee member) / Chiou, Erin (Committee member) / Arizona State University (Publisher)
Created2024
Description
The accelerated pace of globalization necessitates that civil engineering graduates possess a broad spectrum of competencies to meet the evolving needs of a dynamic, interconnected professional environment. This necessity encompasses a blend of practical, personal, and intercultural skills in aspiring engineers, driven by employers' increasing demand for multifaceted skill sets. International research experiences are pivotal in bridging the gap between traditional academic training and the complexities of the real world, offering substantial benefits in terms of personal growth, intercultural understanding, and enhanced research innovation through exposure to diverse methodologies and global professional networks. Despite these advantages and the critical need for engineers adept at navigating the global landscape, participation in international programs remains markedly low among civil engineering graduates, underlining an urgent need for increased engagement and methodological research to elucidate the immediate and long-term benefits of such experiences. This dissertation critically assesses the effects of international research experience on developing key competencies of graduate students, including personal, academic, and professional development, intellectual growth, and intercultural competence. Recognizing the scarcity of rigorous, empirical studies capturing the comprehensive benefits of abroad research, this study adopts a mixed-methods approach, combining quantitative surveys with qualitative interviews to enhance the validity and reliability of findings through data triangulation. Additionally, data collection occurs at multiple time points before and after the experience, providing an in-depth exploration of how such experiences contribute not only to immediate skill enhancement but also to sustained competence development. The research addresses a critical gap in the existing literature, providing evidence-based insights into the multifaceted value and transformative potential of these experiences on graduate engineering competence advancement. The findings indicate improvements in academic proficiency, marked by adopting innovative research techniques and professional capabilities through expanded networks and enhanced communication skills. Moreover, immersion in international settings elevated students' self-reliance and global consciousness, alongside fostering comprehensive growth in intercultural understanding, thereby contributing to their holistic development across personal, intellectual, and professional domains. Through this comprehensive analysis, the study aims to offer actionable recommendations for designing and evaluating future research programs abroad to foster engineering graduates with the advanced competencies required to tackle contemporary challenges and flourish in the global environment.
ContributorsMehrabi Moezabadi, Daniel (Author) / Grau, David (Thesis advisor) / Ariaratnam, Samuel (Thesis advisor) / Edward Gibson, George (Committee member) / Arizona State University (Publisher)
Created2024
Description
In today's data-driven world, privacy is a significant concern. It is crucial to preserve the privacy of sensitive information while visualizing data. This thesis aims to develop new techniques and software tools that support Vega-Lite visualizations while maintaining privacy. Vega-Lite is a visualization grammar based on Wilkinson's grammar of graphics. The project extends Vega-Lite to incorporate privacy algorithms such as k-anonymity, l-diversity, t-closeness, and differential privacy. This is done by using a unique multi-input loop module logic that generates combinations of attributes as a new anonymization method. Differential privacy is implemented by adding controlled noise (Laplace or Exponential) to the sensitive columns in the dataset. The user defines custom rules in the JSON schema, mentioning the privacy methods and the sensitive column. The schema is validated using Another JSON Validation library, and these rules help identify the anonymization techniques to be performed on the dataset before sending it back to the Vega-Lite visualization server. Multiple datasets satisfying the privacy requirements are generated, and their utility scores are provided so that the user can trade-off between privacy and utility on the datasets based on their requirements. The interface developed is user-friendly and intuitive and guides users in using it. It provides appropriate feedback on the privacy-preserving visualizations generated through various utility metrics. This application is helpful for technical or domain experts across multiple domains where privacy is a big concern, such as medical institutions, traffic and urban planning, financial institutions, educational records, and employer-employee relations. This project is novel as it provides a one-stop solution for privacy-preserving visualization. It works on open-source software, Vega-Lite, which several organizations and users use for business and educational purposes.
ContributorsSekar, Manimozhi (Author) / Bryan, Chris (Thesis advisor) / Wang, Yalin (Committee member) / Cao, Zhichao (Committee member) / Arizona State University (Publisher)
Created2024
Description
Halide perovskites are prototypical systems touted as the next generation materials for solar cell applications due to their high-power conversion efficiencies. Engineering the same materials with different morphologies (nanodots, nanoparticles etc.) can result in confinement which creates scalable emitters with immense potential in quantum information science and engineering. Recently, nanocrystal morphology of halide perovskites in form of colloidal solutions has been designed but with only limited quantum efficiency. Engineering quantum dots in-situ in thin perovskite thin films during the crystallization process has the potential to create high efficiency emitters. However, atomic scale microstructural characterization of these embedded emitters is equally challenging due to their electron beam sensitivity and similarity in lattice parameter between the quantum dot and matrix phase. This thesis presents a comprehensive understanding of atomic scale imaging of quantum dots embedded in a Formamidinium lead bromide (FAPbBr3) matrix with details about change in local lattice parameter, size, phase, and composition of the quantum dots using focused ion beam sample preparation technique, low-dose (scanning) transmission electron microscopy ((S)TEM) imaging and energy dispersive X-ray spectroscopy. The (S)TEM images revealed the formation of mixed halide perovskite phases such as FAPbBrxI3-x and FAPbI3 as quantum dots alongside the FAPbBr3 matrix phase. The size of the quantum dots varied from 3-10 nm with clustering of the smaller dots in some areas. The distribution of quantum dots in matrix was analyzed by creating composite phase maps using local diffraction pattern changes between quantum dot and the matrix. The EDX mapping confirmed the presence of all chemical species. The outcomes of this thesis will inspire further studies on how to prepare beam-sensitive cross-sectional TEM samples, cation/anion engineering to create complex quantum dots phases and how these phases react to external stimuli such as light, electric field and heat.
ContributorsMANDALREDDY, SURYA PRAKASH REDDY (Author) / Susarla, Sandhya SS (Thesis advisor) / Yang, Sui SY (Committee member) / Rolston, Nicholas NR (Committee member) / Arizona State University (Publisher)
Created2024
Description
This paper aims to analyze and estimate the factors affecting the State of Health (SoH) of lithium-ion batteries by leveraging advanced evaluation of electrical and chemo-mechanical processes contributing to degradation. The focus was on characterization and collection of empirical battery cycling data investigating the impact of different input variables on SoH prediction to enable predictions for capacity and degradation to validate reliability for second-life applications. The methodology involves collecting cycling data alongside Electrochemical Impedance Spectroscopy (EIS) using a custom test protocol under varied temperatures and charging rates to simulate real-world conditions. The alterations in capacity and the variation of the open circuit voltage with increasing cycles across different temperatures and c rates are also analyzed. The proposed method facilitates a better understanding of the interplay between temperature and C rates on the capacity, open circuit voltage, nominal voltage and EIS response to help estimate the SoH of lithium-ion batteries.
ContributorsMargoschis, Selva Seelan (Author) / Rolston, Nicholas (Thesis advisor) / Chan, Candace (Committee member) / Hwa, Yoon (Committee member) / Arizona State University (Publisher)
Created2024
Description
Over the past decade, gallium oxide has drawn significant attention from the research community due to its exceptional properties. With a high theoretical breakdown field of 8MV/cm, a wide band gap of 4.7eV, and an impressive Baliga’s figure of merit (BFOM) that is 3444 times that of Si, gallium oxide demonstrates great promise for application in high-frequency and high efficiency power electronics. Moreover, gallium oxide stands out as the preferred ultra-wide bandgap semiconductor for power device manufacturing, thanks to the availability of bulk substrates through cost-effective melt growth techniques and high-quality epitaxial layers with low defect density. This paves the way for the commercialization of Ga2O3 based power electronics, positioning it to compete against established SiC and GaN technologies [4], particularly in the multi kilo-volt class medium and high voltage device segment. This thesis presents the investigation of a novel in-situ etching technique for β-which can be carried out within a Metal Organic Chemical Vapor Deposition reactor (MOCVD) using triethylgallium (TEGa) as the etching agent. The experiments were performed in an Agnitron Agilis 100 oxide MOCVD reactor and the TEGa is fed via the showerhead along with nitrogen carrier gas. Due to higher chamber temperature, TEGa undergoes pyrolysis leading to formation of Ga and hydrocarbon species. Hydrocarbons are subsequently removed through the exhaust and Ga adatoms deposit on the sample surface and react with the gallium oxide resulting in formation of volatile gallium suboxide (Ga2O). Since the substrate is kept at high temperature, the suboxide desorbs from surface resulting in etching. Impact of MOCVD chamber parameters like chamber pressure, TEGa flow rate and substrate temperature on etch characteristics like etch rate and surface morphology is studied in detail and a kinetic model for etch rate is developed. Wide range of etch rates from 0.3 µm/hr to 8.5µm/hr is demonstrated by controlling the TEGa molar flow rate. Smooth surface morphology on the etched surface is also demonstrated on (010) and (001) β-Ga2O3 substrate orientations. Furthermore, patterned etching of β-Ga2O3 is also studied with vertical and smooth sidewalls demonstrated along few in plane directions. To conclude, a precise control etching technique is demonstrated based on MOCVD using TEGa as etchant.
ContributorsKatta, Abishek (Author) / Kalarickal, Nidhin Kurian NKK (Thesis advisor) / Susarla, Sandhya SS (Committee member) / Fu, Houqiang HF (Committee member) / Arizona State University (Publisher)
Created2024
Description
Layered oxyhalide magnetic materials have recently emerged as one of the most promising material systems in the field of spintronics and quantum devices because of their large optical anisotropy, magnetic phase transition associated with structural changes, strong antiferromagnetism coupled with weak interlayer bonding and high environmental stability. Despite their attractive magnetic properties and outstanding environmental stability, bottom-up approaches for scalable growth remain limited due to presence of coexisting phases with different stoichiometry in their phase diagram.This work presents the first synthesis of environmentally stable ultra-thin flakes of oxyhalide magnetic CrOCl on Mica and Sapphire substrates using CrCl¬3 and KMnO4 as precursor materials through Atmospheric-Pressure Chemical Vapor Deposition (APCVD) technique in the presence of Argon carrier gas. Comprehensive characterization techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) were employed to confirm the stoichiometry and crystallinity of the grown CrOCl flakes. The findings of the work revealed that the quality of the CrOCl flakes depends on the concentration of the oxygen radicals provided by KMnO4 precursor and substrate temperature. Moreover, morphology and the phase of the material are strongly affected by a variety of factors such as the carrier gas flow rate, the growth time, and the growth temperature. Overall, this work expands the fundamental understanding of the bottom-up growth mechanisms involved in synthesizing such materials thereby contributing to the expansion of the library of stable magnetic oxides with potential applications in advanced technological devices.
ContributorsUppala, Sai (Author) / Tongay, Seth (Thesis advisor) / Yang, Sui (Committee member) / Mu, Linqin (Committee member) / Arizona State University (Publisher)
Created2024