6834 research outputs found
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Comprehensive experimental investigation of liquid piston gas compression for energy storage applications.
No full textA liquid piston gas compressor can alleviate the efficiency issue of a conventional compressed air energy storage system by realizing a near-isothermal compression process due to its capability to incorporate heat transfer enhancement techniques. In this work, a range of heat transfer enhancement techniques is experimentally examined under various conditions. To explore the possibility of further efficiency improvement of the spray injection technique, two different approaches are taken: integrating a metal wire mesh insert and using an air atomization nozzle. With a mesh insert, the possible best condition of each technique does not always lead to the highest isothermal performance because droplet heat transfer is compromised by the existence of the insert. Even though air atomization spray can generate fine droplets, the addition of air accelerates the pressure increase during the compression, which results in a rapid decline of the spray effectiveness. To evaluate the actual applicability, the liquid piston and heat transfer enhancement techniques are evaluated at various pressure levels. The baseline compression is performed at three different initial pressures of 1, 2, and 3 bars with a pressure ratio of 2. A higher-initial pressure leads to a decreased isothermal efficiency. With the gas dissolution considered, the impact of the initial pressure level on an actual efficiency is expected to be greater than what can be observed with the computed efficiency values. Under the same pressure conditions, the use of the spray injection boosts the isothermal efficiencies to 98 – 98.5%. However, with the gas dissolution and spray work input considered, the overall efficiencies are substantially lower than the computed isothermal efficiencies, and this trend is more significant at a higher-pressure level. Aqueous foam and metal wire mesh inserts are evaluated under the same pressure conditions. For both techniques, the results show a consistent trend that a higher-initial pressure leads to a lower isothermal efficiency. In addition, a comprehensive comparative study of the spray injection, aqueous foam, and a metal wire mesh insert is performed based on the experimental results and their working mechanisms
Literally unfinished : a qualitative single case study exploring the factors impacting Texas teachers' responses to unfinished learning in reading due to the COVID-19 pandemic.
No full textThe COVID-19 pandemic created unfinished learning in reading for K–12 students (Curriculum Associates, 2021; Lambert & Sassone, 2020). A survey of public school administrators showed that half of their students were behind grade level in at least one subject area; of those, 64% believed the COVID-19 pandemic instigated unfinished learning (Institute of Education Sciences, 2023). In Texas, the 2020–2021 STAAR reading test showed an overall learning loss of -0.12, which equated to just over three months of loss due to the COVID-19 pandemic (Crowe & Field, 2021). This study explored the factors impacting how four Texas teachers combatted unfinished learning in reading caused by the COVID-19 pandemic. The research utilized Bandura's (1978) reciprocal determinism theory. Considering the voices of teachers in a central Texas school, the qualitative holistic single case study examined how behavioral, environmental, and personal factors impacted the teachers in their journey to combat unfinished learning post-COVID-19 pandemic. To collect data, I used one questionnaire and a one-on-one semi-structured interview. I conducted a thematic analysis using Bandura's (1978) reciprocal determinism theory to analyze the factors impacting teachers in their classrooms while they combat unfinished learning in reading caused by the COVID-19 pandemic. The findings of this study identified how teachers' behavioral, environmental, and personal factors impacted their ability to help their students' unfinished learning in reading. Teachers noted three themes related to environmental factors. Teachers stated that returning to the classroom heavily impacted students' engagement directly after the pandemic, altering their environmental factors due to the restrictions set to keep everyone safe. The teachers in this study also noted that they were given ample resources to combat the pandemic's negative impact on students' reading. Still, unfortunately, those resources took too much time. As a result, the teachers chose to alter the curriculum to engage their students better and combat the unfinished learning in reading, a behavioral factor. As a personal factor, teachers felt that building relationships with their students positively impacted student engagement, thus decreasing unfinished learning in reading. Findings from this study have implications for researchers, district administrators, the Texas Education Agency, and teachers
A charge to keep : a collective case study of the critical success factors for small United Methodist-related colleges.
No full textThis collective case study identifies the critical success factors for small United Methodist-related colleges. Over the past decade, many colleges have closed or merged, citing factors such as enrollment, fiscal health, and leadership as reasons for closure (Grawe, 2018; Marcy, 2020; Zemsky et al., 2020). A predicted enrollment cliff beginning as early as 2026 (Grawe, 2018) could impact enrollment and primary revenue resources, possibly affecting small colleges disparately (Grawe, 2021). This dissertation used three research questions to identify critical success factors in the hope that data reported in this publication can influence decision-making and be a resource for colleges, board of trustee leadership, and the General Board of Higher Education and Ministry. To conduct the research for this study, I used Daniel's (1961) and Rockart's (1979) critical success factor framework to help guide the research questions and data analysis. In this collective case study, I identified four cases: three small United Methodist-related colleges and the Global Board of Higher Education and Ministry (GBHEM). The three colleges have a shared phenomenon of a strong reliance on enrollment to meet institutional financial needs. I identified twenty-two critical success factors from data gathered from the semi-structured interviews with sixteen participants from the three colleges and GBHEM leadership and a review of the historical institution-specific data. These success factors are in the key areas of enrollment, fiscal health, and leadership. In addition, four of the identified findings are uniform for all three college cases: niche programming, reliance on philanthropy to meet budgetary needs, time for the president to cultivate and steward the board of trustee members, and the connection between the church and the college. Four key interest groups are identified: presidents and senior leaders of small United Methodist-related colleges, the leadership at GBHEM, the board of trustee members at small United Methodist-related colleges, and higher education professional organizations and consultants. The research from this study will be shared through academic and professional presentations to key stakeholders and decision-makers and by academic publication
Christ our healer : a constructive dialogue between John Calvin and Gregory of Nazianzus.
No full textMetaphors of disease and healing for sin and salvation have not received much attention in contemporary confessional Reformed circles. This dissertation takes a preliminary step towards a Reformed catholic understanding of these metaphors by evaluating their use by John Calvin and Gregory of Nazianzus. I do not attempt a full systematic account but offer these readings of Calvin and Gregory as a first exploratory step toward a Reformed catholic account of salvation as healing. Study of these figures reveals that the motifs of disease and healing provide a mode of speaking about salvation that holds together forgiveness and transformation while also recognizing the seriousness of sin and the need for divine action. I show that Calvin regularly uses disease as a metaphor for original sin and its impact, enabling him to indicate the pervasive, yet metaphysically accidental, corruption of sin while allowing for continued human action. Calvin uses healing as a metaphor in a much more limited fashion, but he uses healing language to speak organically about the twofold grace of justification and sanctification. Calvin uses healing language to highlight the transformative work of God, and particularly the Holy Spirit, as ongoing in the Christian life and received through the Lord's Supper. Gregory of Nazianzus provides a helpful (and more extensive) account for comparison, especially the use of healing as a metaphor for salvation. Gregory uses disease as a metaphor for sin to push the physical healthy to care for the physically ill and paradoxically describes sin as a chosen disease. Gregory offers a robustly Christological account of salvation as healing, wherein Jesus transformatively heals us by serving as both physician and cure. This healing is received by the Christian through multiple channels, including the ministrations of the pastor, baptism, and loving care for others. This dissertation concludes with a consideration of the possible benefits and drawbacks of using such imagery for salvation in contemporary constructive theology
Statistical covariance monitoring and multivariate modeling with applications to water treatment.
No full textMultivariate statistical process monitoring is a framework for monitoring systems in real time by empirically identifying deviations from expected system behavior. Such deviations indicate a system fault that must be addressed. Techniques for monitoring the mean are well documented in the literature; however, monitoring the covariance of a process is understudied and has many applications to complex systems, such as those found in water treatment. In such systems, some variables are maintained at a setpoint, so only changes in variance are observed. Furthermore, such systems often present complicated scenarios in which data are autocorrelated, non-stationary, non-normally distributed, or have nonlinear relationships. In this work, we present novel control charts designed to monitor the covariance or to jointly monitor the mean and covariance of a system. We explore both statistical and machine learning approaches to detrending a process prior to monitoring, along with the integration of sparse covariance estimation techniques into control charts. Additionally, a case study is presented that details the design and integration of statistical models into a model predictive control framework in which energy efficiency of a closed circuit desalination reverse osmosis system is optimized
Exemplars of female piety : Christianity, context, and gender in medieval Ethiopian and European saints' lives.
No full textThis dissertation examines a specific genre of religious literature—hagiography—as a means to understand the relationship between Christianity and culture in medieval Europe and Ethiopia. Saints' lives served as exemplars of piety and often shed light on the priorities of Christian communities that created and interacted with them. While saints functioned similarly in both Catholic and Ethiopian Orthodox Christianity, the variance in context allowed for different emphases. Put simply, the same saint might be employed or interpreted to convey two distinct models of holiness based on the religious priorities of the context. Utilizing a comparative approach, this dissertation describes and explains how these two specific contexts shaped and accepted representations of women in two compilations of saints' lives, Jacobus de Voragine's Legenda aurea and the Ethiopian Sǝnkǝssar (Book of the Saints). Drawing on insights from World Christianity scholarship, the first chapter argues that medieval Ethiopia should be considered an example of Christendom alongside medieval Europe, highlighting points of continuity and discontinuity between the two contexts. The subsequent close reading of the stories of several virgin martyrs, Mary Magdalene, Mary of Egypt, Helena (the mother of Constantine), and other wives and mothers reveals significant differences in their representation. While the Legenda aurea consistently emphasized virginity among the female saints included in the collection, the Ethiopian Sǝnkǝssar depicted saintly women in a variety of roles. The divergent development of Christendom and theology on topics such as asceticism, clerical celibacy, and marriage reinforced these differences. Studying European and Ethiopian saints' lives in isolation limits our understanding of the history of Christianity. Instead, this comparison challenges the ubiquity of virginity as the model for female piety and ignites further questions regarding women's agency and roles in medieval Christianity. By applying concepts and questions developed within the field of World Christianity to the medieval period, particularly the distinctives of translatability and polycentricity, this project demonstrates that a single model of female piety did not exist in Christendom
The gender gap in healthcare executive leadership : a single case study of mid-level women leaders in healthcare.
No full textIn the realm of executive healthcare leadership, the pervasive gender disparity remains a complex challenge, necessitating a nuanced exploration. This abstract delves into a qualitative case study conducted within a Louisiana health system, focusing on mid-level women leader participants. The overarching goal of this research was to illuminate internal factors contributing to the gender gap in executive healthcare leadership, particularly exploring the phenomenon of a lack of self-advocacy among mid-level women leaders. The methodology employed a qualitative approach, incorporating a mix of questionnaires, focus group sessions, and semi-structured interviews. The research framework, grounded in Galsanjigmed and Sekiguchi's (2023) integrative model, ensured alignment of data collection methods with the phenomenon under investigation. The chosen Louisiana health system, spanning diverse regions, provided the contextual backdrop for the study. Principal findings unveiled a significant gap in self-advocacy among mid-level women leader participants. The exploration of societal influences and biases contributing to the gender gap shed light on the perpetuation and impact on women's career progression and opportunities in healthcare leadership roles. Limited growth prospects within healthcare organizations necessitated a closer look at strategies fostering inclusivity and supporting women's career advancement. Practical applications of this study underscore the imperative for targeted initiatives aimed at empowering mid-level women leaders to advocate for themselves. The identified lack of self-advocacy serves as a focal point for interventions seeking to bridge knowledge deficits and inform evidence-based strategies. Organizations in the healthcare sector are urged to prioritize mentorship programs, diversity, equity, and inclusion (DEI) initiatives, and holistic leadership development approaches. These recommendations aim to cultivate a workplace environment that actively dismantles barriers, fosters inclusivity, and empowers women in their leadership roles. In conclusion, this qualitative case study within a Louisiana health system illuminates the intricate dynamics influencing the gender gap in executive healthcare leadership. The identified lack of self-advocacy among mid-level women leader participants serves as a critical focal point, emphasizing the need for organizational strategies to address this internal challenge. The recommendations put forth provide a roadmap for healthcare organizations to proactively support mid-level women leaders, fostering a more equitable and inclusive leadership landscape
Relationships among national survey of student engagement indicators and academic achievement of Latino/a students in a southwestern public Hispanic serving institution : a quantitative examination.
No full textLatino/a students have the lowest educational attainment among all races and ethnicities in the United States. Despite increasing enrollment trends, institutions struggle to retain and graduate these students. This quantitative ex post facto study examines the relationships between student engagement and academic achievement among Latino/a students at a Southwestern Hispanic Serving Institution (HSI) using the National Survey of Student Engagement (NSSE) Framework. Research question one explores the predictive relationships between the ten NSSE indicators and the academic achievement of Latino/a students. These indicators include higher-order learning, reflective and integrative learning, learning strategies, quantitative reasoning, discussions with diverse others, collaborative learning, student-faculty interaction, effective teaching practices, quality of interactions, and a supportive environment. Research question two tests the fit indices and factor loadings of the NSSE indicators to better understand their relationships and measurement accuracy. The study utilized secondary data from the NSSE survey and student academic records. Descriptive statistics, multiple regression analyses, and confirmatory factor analyses were conducted to examine the predictive relationships and fit of the NSSE indicators. The results indicated that the engagement indicators significantly predicted academic achievement for Latino/a students. Specifically, the ten NSSE indicators are statistically significant predictors of academic achievement and demonstrate good fit indices for this sample population. The study's implications are substantial for the HSI in the Southwestern region, other HSIs nationwide, and higher education faculty across the United States. The findings provide valuable insights for these institutions to develop and implement strategies that enhance student engagement and academic success among Latino/a students. By identifying the key engagement indicators that contribute to academic achievement, institutions can create supportive and engaging learning environments tailored to the needs of Latino/a students. Furthermore, this research underscores the importance of targeted engagement practices and the role of supportive institutional environments in promoting the academic success of minority students. The results offer practical recommendations for policy and practice, emphasizing the need for a holistic approach to student engagement that considers cultural, social, and academic factors to improve educational outcomes for Latino/a students
Characterization of disordered germanide and telluride intermetallic systems.
No full textThis work encompasses a diverse array of materials, spanning intergrown structures, reduced dimensionality, and van der Waals systems, each introducing unique forms of structural complexity such as twinning, disorder, and modulation. Here, I present two new intergrown structures, Gd3 Co2 Ge 7 and Gd5 Co4 Ge 14 , constructed from similar subunits with a direct structural relationship, thereby creating an interesting platform to investigate changes in proximity within the magnetic sublattice. Based on the structural disorder in Gd 3 Co 2 Ge 7 , I use the subunits of the compound to explain the edge of stability within this structure type. Magnetic measurements on Gd5 Co4 Ge 14 reveal intriguing anisotropic behavior, including magnetic ordering, rearrangements, and metamagnetic transitions at low temperatures, indicative of complex magnetic interactions. I synthesize and characterize single crystals of Ln x Co3 (Ge 1–y Sny) 3 (Ln = Y, Gd), allowing for the identification of a new hybrid CoSn–YCo6 Ge 6 disordered structure type. The modeling of the disorder within the Lnx Co3 (Ge 1–ySny ) 3 structure introduces Sn substitution as a means of tunability to the structure type. Magnetic measurements of Yx Co3 (Ge 1-y Sny ) 3 indicate the analogue is a temperature-independent paramagnet. The Gd-analogue shows an elevated effective magnetic moment along the a-axis of 8.48μB , indicating a Co contribution to the magnetism. Co magnetism in the Lnx Co3 (Ge 1–y Sny )3 may depend on the presence of an f-electron-containing lanthanide. Lastly, I investigate the TbSbx Te2−x−δ (δ = vacancies) series, highlighting the structural evolution induced by Sb doping, particularly evident in the distortion of the square net motif. Nonstoichiometric ratios in the TbSb x Te2−x−δ series lead to mixed occupancy of the square net, deviating from charge balancing intrinsic to the idealized structure type and causing superstructures to form. The parent compound, TbTe 2-δ, was synthesized twice, yielding a reticular merohedral twin and an incommensurate structure with a high-temperature phase transition
Low-income student definitions of prestige on selective college campuses.
No full textAs the landscape of higher graduation changes, so too does the definition of a 'prestigious' school. One way in which change is evident is the recent shift in ranking methodologies which now place more emphasis on the experiences of marginalized students. This study seeks to explore the expectations and experiences of Low-income students experiencing food insecurity on selective college campus in conjunction with their definitions of prestige. We found that students think of prestige in ways consistent with existing literature such as the selectivity of institutions, as well as new ways such as alumni success. Student definitions of prestige correlate with two major expectations that students have for their institutions: academic challenge and financial resources. While in some aspects students are experiencing these factors the realities of food insecurity layer new challenges for students to navigate, which requires them to give up some part of their student experience. This study ends with a discussion of the implications for these students and the schools they attend, as well as suggestions for future research and practice