Now showing items 41-60 of 20274

• Investigation of Heat Transfer and Entropy Production of High Temperature Molten Chloride Salts Circulation in Concentrating Solar Power Systems

The global warming and worsening environment on the earth has been a great concern to human society in the last two decades. The major solution to the problem is to use clean and renewable energies for electricity generation, thus reducing the use of fossil fuels and cutting emission of CO2. One of the most feasible approaches for accomplishing the goal is to significantly increase the harvest and utilization of solar energy, using Concentrating Solar Power (CSP) technology combined with Thermal Energy Storage (TES) systems.Heat transfer fluids (HTFs) are used in CSP plants to receive heat from solar concentrator and then transfer it to heat exchanger, power turbine, or thermal storage system. To achieve higher energy efficiency from the CSP systems, the development of a new generation HTF to approach a higher temperature limit by using eutectic high temperature molten chloride salts is sponsored by the U.S. Department of Energy. The first part of this dissertation is the experimental study of the convective heat transfer of the molten salt at high temperatures. For the first time, a circulation system and instrumentation of flow and heat transfer was designed and constructed to measure the heat transfer coefficient of the . Experimental measurement of the convective heat transfer coefficients of NaCl-KCl-ZnCl2 (molar fraction: 13.8%-41.9%-44.3%) inside tubes has been accomplished to find the most suitable heat transfer correlations. This provides valuable information for the design of heat transfer devices in CSP plants that use molten chloride salts as heat transfer fluid and thermal energy storage material. The second part of this dissertation mainly focuses on the analysis to the transient heat transfer phenomenon between the hot fluid and the cold pipe. Currently, most of the modern concentrated solar thermal power plants employ molten salts as the heat transfer fluid to carry the thermal energy from solar concentrators and deliver to thermal storage systems or thermal power plants for the need of power generation. For the startup operation of solar concentrators, molten salts need to be pumped to flow into the pipes which may have lower temperature than the molten salt due to cold ambient overnight or over the suspend period of operation. As the freezing point of various molten salts ranges from 220 oC to 430 oC, preventing the freezing of molten salt flowing in cold pipe is a very important requirement for the safe operation of a concentrated solar thermal power plant. A basic heat transfer analysis of transient heat exchange between molten salts and the flow pipe is conducted to find a criterion or the critical condition of preventing molten salt from freezing. The effects of molten salt flow velocity, heat capacities of molten salt and pipe, dimensions of pipes, and the initial temperatures of salts and cold pipes are all correlated theoretically in the analysis through modeling of transient heat transfer between a pipe and the fluid. The results are very helpful to the understanding and management of a safe startup of hot molten salt flowing in cold pipes on cyclic operations. The third part of this dissertation introduces details about the modeling that provides a fundamental approach for the comparison of various heat transport systems which may have different designs and using different heat transfer fluids/media (gas, liquid, or solid particles) in CSP systems. For various high temperature heat transfer fluids, such as, synthetic oils, various molten salts, and liquid metals, a general criterion is proposed in this work to evaluate the merit of fluids regarding their transport properties. For the goal of transferring a desired amount of heat, a fluid that causes less entropy production is believed to have better figure of merit (FOM). This is due to the fact that entropy production is associated with the destruction of exergy or useful energy. The entropy production in a heat transfer system in a solar thermal power plant includes the part due to the processes of heat addition and removal and the other part due to pressure losses in the flow in heat exchangers and pipes. Theoretical analysis and relevant equations for total entropy production are derived. As an example, the FOM for several heat transfer fluids used in CSP industry are compared for the goal of heat transport in the range of 50 MWth to 600 MWth. This work offers one very important approach leading to the development and optimization of a heat transport system for CSP plant with all factors considered. The investigations included in this dissertation for the heat transfer and system analysis in concentrating solar power technology are of particular interest to the renewable energy engineering community. It is expected that the proposed methods can provide useful information for engineers and researchers.
• Are Medications Effective in Managing Tinnitus?: A Review of the Literature

Objective: The purpose of this project was to evaluate the claims and efficacy of medications marketed towards tinnitus relief for adult humans. The information presented in this literature review provides insight to clinicians regarding medications that have been trialed in adults to treat tinnitus.Methods: This literature review was conducted following steps modeled after Cronin et al. (2008). Articles were identified using the following online databases: PubMed, Ovid, the University of Arizona’s online library and a review of reference lists from excluded Cochrane reviews, systematic reviews, and surveys that were identified during the search process. Results: This review identified 19 articles that fit the search criteria. These articles were categorized into the following nine drug classifications: anticonvulsive/antiepileptic, benzodiazepines, vitamins/minerals/antioxidants/herbals, anesthetics, antagonist drugs, vasodilators, antidepressants, anti-inflammatories/corticosteroids, and anticoagulants/antithrombotic. Conclusions: Future research is needed to validate the effectiveness of the medications reviewed in this project. Treatment approach for tinnitus is complex as tinnitus is multifaceted. Without the exact knowledge of etiology and mechanisms involved, treatment results for tinnitus are unpredictable. Starting or stopping any medication is not recommended without a physician’s approval.
• Integrative Health Education For Insomnia Among The Older Adult Population

Purpose This quality improvement (QI) project aims to evaluate the healthcare providers’ knowledge and intent to use evidenced-based integrative health (IH) education plan for insomnia in older adults at the Cornerstone Long-term Acute Care Hospital in Round Rock, TX. Background The American College of Physicians Clinical Practice Guideline (CPG) for chronic insomnia for the adult population contains two recommendations, the use of cognitive-behavioral therapy and a shared-decision-making approach by the clinician and the patient discussing whether pharmacological intervention is warranted in case the CBT was ineffective. This project identifies alternative nonpharmacological approaches in a situation where both the first and second recommendations are not effective, appropriate, or the risks outweighs the benefits. Methods The Ottawa Model of Research Use (OMRU) framework inspired by Rogers Diffusion of Innovation theory guided the process of this quality improvement project, which superseded a quantitative descriptive design. This design was utilized to evaluate the healthcare providers’ knowledge of evidence-based integrative health nonpharmacological interventions for insomnia. A Google.doc pretest survey link was provided followed by a PowerPoint education presentation about the history, uses, and benefits of acupuncture, aromatherapy, and music therapy for insomnia. A posttest survey link was provided after the presentation to re-assess their knowledge and intent to use IH approaches to their practice. The pretest and posttest survey results were used as a piece of quantifiable information for analysis. Results Data collection took place in one evening. Two participants participated in this project presentation, all of which were Caucasian female, registered nurses. Both completed the pretest and posttest surveys. There were score increases seen in knowledge, comfortability, and intent to use acupuncture, aromatherapy, and music therapy as IH approaches to their practice and a clear improvement from pretest survey to posttest survey. Conclusion The pretest and posttest surveys revealed positive results of evidence-based IH approaches education presentation to the healthcare providers’ knowledge and intent to use to their practice. Future high-quality studies that focus on adapting the IH approaches into the providers’ practice would likely lead to the conceptualization of the 3rd recommendation of the existing CPG for insomnia among adults
• Teaching Students With Emotional and Behavioral Disorders Self-Reported Practices: What Is Working and What Are the Needs?

Students with emotional and behavioral disorders (EBD) exhibit a wide variety of difficult behavior, and the responsibility of educating them is equally difficult. Students with EBD face historically bleak outcomes. Additionally, EBD teachers have had a continual nationwide shortage. They have the highest turnover rate and have more teachers on emergency certification than any other teaching group. Multiple literature analyses have concluded that evidence-based practices are widely absent in EBD classrooms, and student outcomes have had dismal improvements (Bradley et al., 2008; Gage et al., 2010; Harrison et al., 2019; Simpson et al., 2011). However, most of this research has focused on either specific intervention strategies or meta-analysis of previous literature (Bradley et al., 2008; Conroy, 2016; Conroy et al., 2008; Freeman et al., 2019; Lewis et al., 2019; Lloyd et al., 2019; Wagner et al., 2006) and have not focused on what teachers report happening in EBD classrooms. This mixed-method exploratory study examined the resources teachers reported using to support their students, the prevalence of evidence-based practices, and whether there is a correlation between access to evidence-based resources and teachers’ intent to continue teaching and confidence in their ability. This study explores some of the current instructional practices, barriers, and needs occurring in classrooms supporting EBD students in Arizona. Implications and recommendations for future research are included.

• Geometrical Optics Restricted Eavesdropping Analysis of Secret Key Distillation and its Application to Satellite-to-Satellite Free Space Links

The quantum cryptography theoretically aims to promise unconditional information security in the physical layer against an omnipotent eavesdropper. However, such a conventional assumption of an all-powerful eavesdropper can be too strict for certain practical implementation scenarios and can be relaxed considerably. This dissertation reviews the relevant theories on secret key rate bounds, proposes a geometrical optics restricted eavesdropping model and studies secret-key distillation across a lossy and noisy quantum wiretap channel between Alice and Bob, with a separately parameterized realistically lossy quantum channel to the eavesdropper Eve. We show that under such restricted eavesdropping, the key rates achievable can exceed the secret-key-distillation capacity against an unrestricted eavesdropper in the quantum wiretap channel. Furthermore, we show upper bounds on the key rates based on the relative entropy of entanglement. Then we apply this model to the realistic secret key distillation over a satellite-to-satellite free space optics channel starting with a straightforward case where we assume a limited-sized aperture eavesdropper (Eve) in the same plane of the legitimate receiver (Bob) and determine the secret key rate (SKR) lower bounds correspondingly. We first study the input power dependency without assumptions on Bob’s detection scheme before optimizing the input power to determine lower bounds as functions of transmission distances, center frequency or Eve aperture radius. Then we calculate analytical expressions regarding the SKR lower bound and upper bound as transmission distance goes to infinity. Then we study one of Bob’s possible corresponding defense strategies in this realistic application model of secret key distillation over satellite-to-satellite free space channel in which we impose a reasonable restriction on the eavesdropper by setting an exclusion zone around the legitimate receiver. We first study the case where the eavesdropper’s aperture size is unlimited, so her power is only restricted by the exclusion zone. After that we limit Eve’s aperture to a finite size and study the case when her aperture is in the same plane of Bob, investigating how an exclusion zone can help improve security. Correspondingly, we determine the secret key rate lower bounds as well as upper bounds. We show that by putting reasonable restrictions on the eavesdropper through the realistic assumptions of an inaccessible exclusion zone, we can increase the key rate in comparison to those without and do so with relatively lower transmission frequency. In the end, we study the secret key distillation over a satellite-to-satellite free space optics channel in which we assume that the eavesdropper’s limited sized aperture can be dynamically positioned to gain advantages over the communication parties, and we determine the achievable key rate lower and upper bounds with respect to different scenarios. We first study the case where Eve is behind Bob, and we prove that the optimal eavesdropping strategy for her in long-distance transmission case is to place her aperture on the beam transmission axis and set Bob-to-Eve distance equal to Alice-to-Bob distance. We also show that the achievable key rate would be characterized by a Bessel function integral related to Eve’s position in a short-distance transmission case. We then investigate the case where Eve is before Bob and show similar results with Eve’s and Bob’s roles exchanged. For our analyses we also incorporate specific discrete variable (DV) and continuous variable (CV) protocols for comparison.
• Evidence-Based Education on Child Maltreatment Risk Factors for Pediatric Primary Care Providers

Purpose: The purpose of this quality improvement (QI) Doctor of Nursing Practice (DNP) project was to educate pediatric providers on the Safe Environment for Every Kid (SEEK) model to improve their knowledge of psychosocial risk factors for child maltreatment (CM) and support their identification of these targeted risk factors in the primary care setting. Background: Child maltreatment is a significant problem in the United States (US) that is highly preventable. Pediatric primary care providers (PCPs) are in a unique role to aid prevention efforts; however, the majority of providers do not routinely screen for CM and associated psychosocial risk factors. Key barriers to provision of CM screening and anticipatory guidance include lack of provider knowledge, training, comfort, and lack of validated and recommended screening tool. The SEEK model was created to address this gap in care and serves as an effective, evidence-based program for use in the primary care setting to educate and support providers in preventing child maltreatment. Methods: This QI project utilized pretest/posttest design with an evidence-based educational PowerPoint presentation that summarized SEEK provider training modules. Participants were pediatric PCPs from Agave Pediatrics in Arizona. The 10-question pretest survey and 11-question posttest survey contained five of the same knowledge-based questions about presentational content. Additional survey questions measured participant perception of knowledge level, as well as level of comfort assessing and addressing CM risk factors. Results: Four providers (n=4) completed the pretest survey, educational presentation, and posttest survey. Project data demonstrate that there was statistically significant (p<0.05) improvement in knowledge following educational intervention. Participants’ perception of their knowledge following educational intervention demonstrated an improvement, although not statistically significant (p=0.88). All participants agreed that educational presentation increased their levels of comfort in assessing and addressing psychosocial stressors and risk factors associated with child maltreatment. Conclusions: This DNP projected demonstrated a statistically significant improvement in provider knowledge following an educational presentation on CM and SEEK model. This project adds to current body of evidence supporting educational interventions as an effective method to improve provider knowledge of CM risk factors and associated psychosocial concerns, specifically through the utilization of the SEEK model.
• Integrated Statistical Modeling of Engineering Data with Shared Information

Data has become exceedingly important to organizations, especially with regard to decision making. The large amount of available data is crucial in engineering applications as it ensures the understanding of the problem and the efficient execution of the solution. Studies have also shown that the employment of large amounts of data in engineering applications makes it easier for the data-driven model to generate insights that can be acted on in the best interest of the optimal solution. With the existence of multiple data sources, we can unveil hidden patterns and trends to determine possible relationships in the most complex engineering applications. This has traditionally been achieved by building single statistical models independently to explain single data sources. Nonetheless, when there exists a correlation among several data sources, a single statistical model strategy has been shown to be time consuming, result in loss of pertinent information, and is tedious. It is against this backdrop that this dissertation aimed at developing statistical models that can accurately predict the responses of three important engineering applications. To achieve this aim, this dissertation developed three integrated statistical modeling (ISM) techniques for these three applications. The choosing of the techniques was informed by the fact that they have shown great performance benefits. First was the modeling of multivariate profiles. In some manufacturing processes, profile data are collected to monitor process variations. In situations when multiple profiles are collected together, correlations might exist across profiles. Modeling these multivariate profiles requires describing both within and between profile correlations. Second was the discovery of material oxides, which often suffers from data scarcity. In some cases, collecting data from the target source can be expensive, while there are auxiliary data sources that are cheaper to collect. In such situations, auxiliary data sources can be exploited to improve the performance of the expensive target data. Third was the investigation of data by grouping information where subjects are clustered into various groups. Through employment of the above strategies and applying them to examples and case studies, it was evident that improvement of the prediction accuracy can be realized by exploiting the within-group and between-group characteristics in these data sources, instead of modeling each data source separately. In general, transferring the knowledge across sources is complicated for most real-world systems, and often traditional modeling approaches are not adequate to capture the relations, when data are not stationary or are changing abruptly in a small interval. In addition, the modeling time can be burdensome with the increased number of sources and observations. Hence, developing efficient and flexible frameworks for multiple correlated data sources is imperative. This dissertation proposed novel ISM techniques to deal with the complicated scenarios associated with correlated data sources. This study further demonstrated that the proposed ISM techniques have the ability of helping to model correlation among different data sources into a single modeling framework. The major advantage of the proposed ISM methods was found to be their flexibility over individual modeling of each data sources. The study concludes by proving that it is possible to effectively handle data nonstationarity with reasonable computation loads.

• Electronic Cigarettes: Anesthetic Considerations to Improve Clinical Practice

Purpose. The purpose of this quality improvement project was to develop and present an educational video presentation to anesthesia providers regarding anesthetic considerations for patients who use electronic cigarettes, and to assess whether the educational presentation causes a change in the anesthesia providers’ attitudes, knowledge, confidence, and intent to change clinical practice. Background. The prevalence of electronic cigarette use has been increasing, especially among adolescents and young adults. Research findings have associated electronic cigarette use with multiple adverse health effects that should be considered when providing anesthetic care to these patients. Anesthesia providers may not be fully informed about these effects and may not be adequately screening patients for electronic cigarette use prior to surgery. Methods. Participants were instructed to take a pretest survey, view a pre-recorded educational presentation, and then complete a posttest survey. The surveys were intended to assess for changes in anesthesia providers’ self-reported attitudes, knowledge, confidence, and intent to change clinical practice before and after viewing the presentation. Results. Three out of 25 anesthesia providers participated in the project. All participants reported improved attitudes towards the importance of anesthetic considerations for electronic cigarette users, increased knowledge, increased confidence in caring for patients who use electronic cigarettes, and a positive intent to include questions about electronic cigarette use when interviewing patients preoperatively as well as to incorporate the anesthetic considerations described in the educational presentation in their clinical practices. Conclusions. Although the survey results showed changes had occurred in the outcome measures, due to the limited sample size no conclusions could be drawn.
• Fantasies of Ambivalence: Romance and Historical Consciousness in Eighteenth-Century Britain

“Fantasies of Ambivalence: Romance and Historical Consciousness in Eighteenth-Century Britain” examines the relationship between romance and partisan history-writing in Britain following the English Civil War and 1688 Revolution. Considering works of fiction by Delarivier Manley, Marie-Catherine d’Aulnoy, Horace Walpole, Ann Yearsley, and Walter Scott alongside works of traditional historical and political discourse, this dissertation argues that that historical romance maintained a continuously evolving literary presence in eighteenth-century Britain. During this period, the quintessentially romantic formal characteristics of anachrony, structural repetition, function-driven narrative, and complex allegory reappeared across multiple genres, including the keyed secret history and the Gothic novel, each of which may be considered a form of “historical romance” and each of which played their own roles in meditating British consciousness of the relationship between past and present. The formal characteristics of historical romance made it exceptionally able to register conflicting viewpoints, sentiments, or beliefs simultaneously without subordinating one to the other or otherwise reconciling them. In many cases, writers deployed this capability to act as the handmaidens of political ideology, using romance forms to conceal the contradictions or fissures in partisan visions of the British past. Yet, in certain cases, writers of historical romance also acted as challengers to ideology, exposing those contradictions and fissures. Increasingly, as the hyper-partisanship of the early eighteenth century yielded to the doubts of the mid-century and the disenchantment of the 1790s, historical romance served more as a mechanism of ideological critique than of partisan reinforcement. I track this shift by observing the transition from the literary predominance of the keyed secret history in the early eighteenth century to that of the palimpsestic neo-Gothic romance in later decades, a transition which saw the replacement of romance’s long-standing historiography of fantasy by a historiography of fantasy echoes.