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Multi-Physics Modeling and Simulations of Heat Pipe Cooled Graphite Moderated Micro Reactor
No full textHeat pipe micro reactors are compact, innovative nuclear reactors that utilize heat pipe technology to manage heat transfer efficiently. The advantage of heat pipe micro reactors lies in their reduced complexity, high efficiency, and ability to provide stable power in various scenarios where traditional, larger reactors are not feasible or practical. This research presents a multi-physics analysis focusing on a proposed design of 0.5 MWth heat pipe cooled, graphite moderated nuclear micro reactor. The main driver of the design study was to achieve enhanced safety characteristics, while maintaining long core lifetime and excellent power producing capabilities. The envisioned outcome was a versatile design adaptable to various purposes including remote locations and space applications.
In order to assess the safety characteristics of the design, investigations of the main reactor parameters were performed through developing a multi-physics tool, that included a neutronic model, point kinetics model, thermal conduction model, heat pipe model, and mechanical model. All models were coupled through a python wrapper to allow for appropriate data exchange. The neutronic model of the design was developed using MCNP and Serpent Monte Carlo codes, in order to calculate important parameters including criticality, control devices worth, power distribution, and temperature reactivity coefficients. The thermal conduction model of the solid-state core was developed and coupled to a heat pipe model using Ansys Fluent, to calculate the temperature distribution in the reactor, while Ansys Mechanical was employed to conduct structural mechanical analysis through performing calculations of the stress, strain, and total deformation of the core. Multi-physics simulations of the design were carried out to provide analysis of both steady-state normal operating conditions and transient scenarios, including accidents related to heat pipe and control drum failures. The obtained results were used to assess the safety aspects of the proposed design and provide valuable insights necessary for the development of heat pipe micro reactors in the near future
Advancing Stress Detection: Towards Real-Time, Naturalistic, and Personalized Artificial Intelligence Approaches for Stress and Mental Disorder Detection
No full textThis dissertation presents a comprehensive exploration of Machine Learning (ML) and Deep Learning (DL) methodologies for the detection, prediction, and analysis of stress and stress-related mental disorders (MDs). The research begins with a systematic review of existing ML algorithms, preprocessing techniques, and data types used in stress detection, highlighting the superior performance of Support Vector Machine (SVM), Neural Network (NN), and Random Forest (RF) models. The review also underscores the prevalent use of physiological parameters, such as heart rate measurements, as stress predictors, and identifies significant research gaps, including model interpretability, personalization, the incorporation of naturalistic settings, and real-time processing capabilities.
Addressing these gaps, the dissertation presents a series of studies. The first study explores a machine learning-based method for continuous monitoring and identification of stress in a naturalistic setting among college students, using a mobile health (mHealth) application and wearable wrist-worn sensors. The XGBoost model was found to be the most reliable in this context, with an accuracy of 84.5%.
The second study proposes a stress detection methodology that utilizes an array of deep learning models, including feedforward neural networks (FFDNN), Conv1D, long short-term memory (LSTM), hybrid Conv1D-LSTM, and Conv1D-LSTM with attention mechanism. The hybrid Conv1D-LSTM model augmented with an attention mechanism outperformed the other models, achieving a cross-validation accuracy of 0.89 and an area under the curve (AUC) score of 0.94. The final study explores the potential of individualized ML and DL algorithms in accurately identifying stress responses in individuals afflicted with Post-Traumatic Stress Disorder (PTSD). The findings demonstrate that individualized models, particularly advanced deep learning models such as LSTM and hybrid CNN-RNN models, consistently surpass standard models in accurately identifying stress in PTSD patients.
In conclusion, this dissertation underscores the importance of employing advanced ML and DL techniques, such as hybrid models and attention mechanisms, and individualized approaches to improve stress detection performance. The findings contribute significantly to the field of digital health, suggesting innovative strategies for monitoring and managing stress in various populations
Border Commuting Student Experiences: Developing Transborder/Transfronterize Identities
No full textOscar Martinez argues that an international border is a ���line that separates one nation from another��� to keep the people in the poor country out of the rich country (1994:5). Border commuters cross international borders daily/weekly and participate in each country's society, straddling both physical and non-physical boundaries in the borderlands (Anzaldua 1987; Carter 2006). This thesis focuses on the identity development of high school border commuters, referred to as transfronterize/transborder students (Stephen 2007; Iglesias-Prieto 2011). In addition to the analysis of transborder complex identities and Prudence Carter���s (2006) concept of student ���boundary straddling,��� this study uses Falc��n Orta & Orta Falc��n���s (2018) Transborder Identity Formation Framework to examine how the experiences of border commuter high school students develop transfronterize/transborder identities. The guiding question in this study is: ���In what ways does border commuting for educational purposes shape the identity development of high school transborder/transfronterize students?��� Two specifying questions follow: ���How well do Falcon Orta and Orta Falcon���s Identity Formation Framework apply to transborder high school students?��� and ���How are the identity development experiences of high school transborder students similar/different to that of transborder college students based on the existing theory?��� To answer these questions, qualitative methods were used to explore transborder students��� self-perception, educational aspirations, and border commuting experiences. The findings indicate that the existing framework for transborder college students applies to the experiences of transborder high school students; however, younger students have influential factors that do not apply to college students and vice versa in developing their complex transborder identities
Immediate and Lifelong Consequences of In Utero Exposure to Alcohol: A Systemic and Multi-organ Approach
No full textPrenatal alcohol exposure (PAE) has an estimated prevalence of ~8 to15% in North America, making it the largest single cause of neurodevelopment disabilities and growth deficits. There is increasing recognition that Fetal Alcohol Spectrum Disorders (FASDs) is a ���whole-body��� disease, impacting the health of the individual immediately in utero and persistently throughout the lifespan, likely due to epigenetic alterations and stem cell reprogramming. To gain a better understanding of the more immediate consequences of PAE, I first characterize the consequences of PAE on the placental transcriptome, correlating these changes to observed differences in fetal growth and placental blood flow in a murine model. Secondly, I utilize a murine neural stem cell (NSC) culture model equivalent to mid-1st to 2nd trimester in humans to study the adaptive role of ethanol sensitive Gag-Like Proteins (GLPs) in NSCs. In addition, I also focus on the lifelong impact of PAE, characterizing baseline health differences in young adult (5 mo) PAE rats and identifying an association of a pro-inflammatory state of mesenteric adipose tissue and liver with changes in behavior. Subsequently, I examine transcriptomic differences in the enteric organs (mesenteric adipose tissue and liver) that occur as a response to a health stressor (cerebrovascular ischemic stroke), correlating differences in response to observed impaired recovery post-stroke. Overall, this dissertation focuses on examining PAEinduced (mal)adaptations at different critical time points in development and in life
Improving the SPEE Monograph 3 Approach through MLR-Normalization
No full textIn 2008, as part of a modernization effort, the Securities and Exchange Commission (SEC) adopted rules restricting undeveloped reserves to acreage directly offsetting existing wells unless reliable technology could justify greater distances. This rule significantly limited the amount of proved undeveloped (PUD) reserves that could be disclosed in unconventional plays, which require more wells to fully develop than their conventional counterparts. Recognizing the industry's need, the Society of Petroleum Evaluation Engineers (SPEE) published its third monograph in 2010.
The SPEE Monograph 3, while innovative, limited its calculations to estimated ultimate recovery (EUR) normalized by completed lateral length (CLL). It otherwise overlooks other operator-controlled variables, such as completion design, location and well depth, which are shown to have a significant impact on performance.
In the following thesis, I augment the SPEE Monograph 3 approach with multiple linear regression (MLR) models using certain operator-controlled variables from publicly available sources. I generate an equation to explain additional variability in performance and normalize EURs. Finally, I follow the SPEE Monograph 3 recommendations for estimating proved areas and volumes, comparing the results to CLL-normalization alone.
In the Woodford case study, my proposed workflow was shown to reduce minimum analogs required for the initial establishment of reliable technology by 27%, resulting in the booking of PUDs beyond direct offsets 18 months sooner. Additionally, the use of MLR-normalization resulted in proved areas up to 15% larger and proved volumes up to 31% larger than CLL-normalization.
Modern software and data availability make MLR models achievable for operators of all sizes. My work utilized RStudio, a free programming software with many statistical packages, and Enverus, an online subscription service to oil and gas data. With some effort, MLR modeling is programmable, making it easy to integrate into existing PUD workflows
Multi-coil Wireless Power Transfer Systems Analysis and Design
No full textWireless power transfer (WPT) technology is growing fast and has been used for various applications. experiencing rapid growth and finding applications across various sectors. Emerging markets, such as consumer electronics, electric vehicles, and medical implants, are actively exploring the integration of wireless power transfer as an energy solution. Numerous studies have advanced proposals for WPT coil designs, resonant circuit designs, and the incorporation of wide bandgap devices into WPT systems. Concurrently, multi-coil WPT systems, employing more than one coil on either the transmitter or the receiver, have gained prominence. Among these, three-phase wireless power transfer systems have demonstrated several advantages and exhibit potential as viable solutions for technical challenges encountered in the industry.
The first research topic revolves around wireless lithium battery charging, a critical component of electric vehicles. The charging process for lithium batteries requires a sequential application of constant current (CC) charging succeeded by constant voltage (CV) charging. This paper presents a novel reconfigurable compensation topology designed for three-phase wireless charging systems. The reconfigurable compensation topology facilitates a seamless transition between the inductor-capacitor-capacitor-parallel (LCC-P) configuration and the inductor-capacitor-capacitor-series (LCC-S) configuration. This enables the output to exhibit CC and CV characteristics, respectively.
The second research topic delves into wireless power transfer for autonomous underwater vehicles (AUVs). Charging AUVs presents unique challenges due to insulation and water leakage issues when submerged. The application of three-phase wireless power transfer encounters complexities, primarily stemming from uncontrollable docking angles leading to rotational misalignment issues. In response to these challenges, a three-phase wireless power transfer coil resistant to rotational misalignment has been proposed, simulated, and tested
Art (Spaces) Imitates Life? An Exploration of Arts-Centered Spaces and Their Degree of Accessibility to Immigrant Communities
No full textThis literature review is designed to answer two questions. First, whether art spaces are welcoming spaces for immigrants? Second, what conditions may prompt immigrants to interact or disengage with art spaces? Literature from cultural geography, sociology of culture, urban studies, race, ethnicity, and migration have demonstrated that institutions such as the art museum have historically been sites of domination (Anderson 2006; Cooks 2011; Lonetree 2012). Despite this, museums have displayed an effort to change, while marginalized communities embody the capacity to partake in placemaking endeavors regardless of these constraints (Hooper-Greenhill 2000; Roberts 2018, 2020; Lipsitz 2011; Cook 2011; Lonetree 2012; Jenkins 2010; Jamal 2010, Espiritu 2010, Maira 2010, Stern et. al. 2010). Moreover, art-spaces have been shown to benefit people in both an individual and communal sense (Grodach 2010, 2011; Eaves 2014; Eisner 2012). At the same time, the literature shows that immigrants tend to prefer more informal or private venues to partake in the consumption or creation of art. Although this is the case, we cannot discern exactly why this dynamic is occurring (Stern et. al 2010). Literature regarding cultural capital and strategic assimilation point to possible theoretical explanations of this dynamic, but further research must be conducted to fully address this discrepancy (Bourdieu 1977; Lamont and Lareau 1988; Lacy 2007). In the completion of this literature review, I also offer suggestions to improve existing art spaces based upon the concepts of the Black Spatial Imaginary and Community Asset Mapping (Lipsitz 2011; Villanueva 2020, 2021)
Vision-Language Models: The Overlooked Role of Synonyms
No full textIn the past few years, contrastively pre-trained Vision-Language Models (VLMs) such as CLIP, have significantly propelled advancements in multimodal applications. Pre-trained on internet scale images and captions VLMs learn to associate relevant text and images, making them key to downstream applications such as visual chatbots and text-to-image generation diffusion models. However, there has been limited analysis of these models��� pre-training datasets, primarily due to the challenges posed by their large scale. Moreover, given that these datasets lack human annotation, determining the presence of specific visual concepts within them poses a significant challenge.
We address this challenge by using a Large Language Model and count the pre-training texts that contain synonyms of any given visual concept. Contrary to popular belief we discover that these pre-training datasets exhibit a long-tailed concept distribution, resulting in biased performance in VLMs.
Next we propose a novel prompting strategy that leverages synonyms to improve the performance of VLMs for zero-shot recognition. Instead of prompting VLMs using original class names, we use the most frequent synonyms found in the pre-training texts. Finally we propose a novel light-weight retrieval augmented strategy, that achieves a new state-of-the-art for the zero-shot recognition
Effect of Select Interpretive Story-Telling Techniques on Narrative Transportation and Engagement Among Youth Educational Travelers
No full textThis study examined the effect of select story-telling strategies interpreters use on engagement and narrative transportation of youth educational travelers. Engagement is the subjective state of motivation that occurs when one���s attention is focused on a story being told. Narrative transportation can also occur during story experiences. The traveler (i.e., reader, listener, spectator) is carried, via imagination, to the destination of the story; a different time, place, and set of circumstances. Heritage interpreters and tour guides for youth educational travel experiences use a variety of techniques to invite narrative transportation and engagement, but the effects of such techniques have not been studied experimentally. Four strategies were evaluated: use of visual aids, verisimilitude, use of music, and self-relevance elicitation. One hundred forty-four experience observations from 18 4-H youth enrolled in an educational travel experience to Spain were analyzed. Youth visited different sites in Barcelona and Madrid. During the daily reflection period, the researcher told a fictional story set in the site or sites visited that day. The four techniques were systematically varied across eight different stories to determine the relative effect of each technique on narrative transportation and engagement. After listening to each story, youth completed an electronic questionnaire measuring narrative transportation, engagement, and down-stream outcomes (perceived value of time spent and proclivity to recommend). Verisimilitude and self-relevance increased engagement and engagement increased narrative transportation. The effects of music and visual aids were not significant. Narrative transportation increased with increases in engagement, and perceived value of time spent listening to the story and proclivity to recommend were positively correlated with narrative transportation
Unraveling the Role of TET-Mediated Epigenetic Regulation in Heart
No full textDifferent types of DNA modifications play a crucial role in the epigenetic control of gene expression in organisms. Traditionally, the major attention has been focused on 5-methylcytosine (5mC), a major form of DNA modification. However, the discovery of the TET enzymes has sparked new research on their major catalytic product, 5-hydroxymethylcytosine (5hmC). The enzymatic activity of TET proteins is intricately regulated by metabolites under physiology or pathological conditions. In addition, metabolic reprogramming plays an essential role in regulating the development and regeneration of heart tissues. However, how TET enzymes regulate cardiac metabolism in response to external stresses still remain poorly understood.
In this study, we investigated the consequences of Tet triple knockout (Tet-TKO) in mouse embryonic stem cells (ESCs) and observed notable alterations in glucose metabolism. These changes were marked by enhanced glucose uptake and glycolysis, likely owing to the upregulation of genes critical for glucose metabolism. Furthermore, these cells exhibited defects in glucose-dependent differentiation, suggesting that cells with epigenetic defects might display metabolic vulnerability when exposed to external nutritional cues.
Maternal exposure to balanced nutrition is critical for supporting embryonic development. We observed that maternal exposure to a high-fat diet led to noncompaction cardiomyopathy (NCC) in embryos at E15.5. At the molecular level, maternal HFD exposure resulted in significantly reduced 5hmC production and chromatin remodeling in embryonic heart tissues collected from E15.5 embryos. Interestingly, maternal vitamin C treatment countered the negative impact of HFD exposure and restored the metabolic changes observed in pregnant mice, as well as the NCC phenotype observed in E15.5 embryos. This restoration is possibly due to the replenishment of iron, a co-factor of the Tet enzyme, in its reduced form. We further used a cardiac-specific Tet-triple knockout mouse model to confirm that the cardioprotective outcome of maternal vitamin C treatment in HFD conditions is attributable to the enhanced activity of TET enzymes.
There is a mutual influence between obesity and myocardium dysfunction. We report herein abnormal systemic energy homeostasis and obesity phenotypes in adult mice upon disrupting DNA methylation and demethylation balance in heart tissues. We observed that myocardium-specific Tet deletion had minor effects on heart size, structure, and function. By contrast, Tet ablation in heart resulted in increased whole-body weight, accompanied with higher blood glucose and lipid levels. In parallel, Tet-TKO mice exhibited increased glucose intolerance, insulin insensitivity and body fat, which mimicked the obesity phenotype.
Collectively, our findings establish the pivotal role of the TET family of dioxygenases in maintaining proper systemic hemostasis, thus enhancing our understanding of the intricate interplay between epigenetic modifications and cellular metabolism