ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- Genre: Masters Thesis
Description
In this thesis the performance of a Hybrid AC System (HACS) is modeled and optimized. The HACS utilizes solar photovoltaic (PV) panels to help reduce the demand from the utility during peak hours. The system also includes an ice Thermal Energy Storage (TES) tank to accumulate cooling energy during off-peak hours. The AC runs continuously on grid power during off-peak hours to generate cooling for the house and to store thermal energy in the TES. During peak hours, the AC runs on the power supplied from the PV, and cools the house along with the energy stored in the TES. A higher initial cost is expected due to the additional components of the HACS (PV and TES), but a lower operational cost due to higher energy efficiency, energy storage and renewable energy utilization. A house cooled by the HACS will require a smaller size AC unit (about 48% less in the rated capacity), compared to a conventional AC system. To compare the cost effectiveness of the HACS with a regular AC system, time-of-use (TOU) utility rates are considered, as well as the cost of the system components and the annual maintenance. The model shows that the HACS pays back its initial cost of $28k in about 6 years with an 8% APR, and saves about $45k in total cost when compared to a regular AC system that cools the same house for the same period of 6 years.
ContributorsJubran, Sadiq (Author) / Phelan, Patrick (Thesis advisor) / Calhoun, Ronald (Committee member) / Trimble, Steve (Committee member) / Arizona State University (Publisher)
Created2011
Description
While much effort in Stirling engine development is placed on making the high-temperature region of the Stirling engine warmer, this research explores methods to lower the temperature of the cold region by improving heat transfer in the cooler. This paper presents heat transfer coefficients obtained for a Stirling engine heat exchanger with oscillatory flow. The effects of oscillating frequency and input heat rate on the heat transfer coefficients are evaluated and details on the design and development of the heat exchanger test apparatus are also explained. Featured results include the relationship between overall heat transfer coefficients and oscillation frequency which increase from 21.5 to 46.1 Wm-2K-1 as the oscillation frequency increases from 6.0 to 19.3 Hz. A correlation for the Nusselt number on the inside of the heat exchange tubes in oscillatory flow is presented in a concise, dimensionless form in terms of the kinetic Reynolds number as a result of a statistical analysis. The test apparatus design is proven to be successful throughout its implementation due to the usefulness of data and clear trends observed. The author is not aware of any other publicly-available research on a Stirling engine cooler to the extent presented in this paper. Therefore, the present results are analyzed on a part-by-part basis and compared to segments of other research; however, strong correlations with data from other studies are not expected. The data presented in this paper are part of a continuing effort to better understand heat transfer properties in Stirling engines as well as other oscillating flow applications.
ContributorsEppard, Erin (Author) / Phelan, Patrick (Thesis advisor) / Trimble, Steve (Committee member) / Calhoun, Ronald (Committee member) / Arizona State University (Publisher)
Created2011
Description
Thermal interface materials (TIMs) are extensively used in thermal management applications especially in the microelectronics industry. With the advancement in microprocessors design and speed, the thermal management is becoming more complex. With these advancements in microelectronics, there have been parallel advancements in thermal interface materials. Given the vast number of available TIM types, selection of the material for each specific application is crucial. Most of the metrologies currently available on the market are designed to qualify TIMs between two perfectly flat surfaces, mimicking an ideal scenario. However, in realistic applications parallel surfaces may not be the case. In this study, a unique characterization method is proposed to address the need for TIMs characterization between non-parallel surfaces. Two different metrologies are custom-designed and built to measure the impact of tilt angle on the performance of TIMs. The first metrology, Angular TIM Tester, is based on the ASTM D5470 standard with flexibility to perform characterization of the sample under induced tilt angle of the rods. The second metrology, Bare Die Tilting Metrology, is designed to validate the performance of TIM under induced tilt angle between the bare die and the cooling solution in an "in-situ" package testing format. Several types of off-the-shelf thermal interface materials were tested and the results are outlined in the study. Data were collected using both metrologies for all selected materials. It was found that small tilt angles, up to 0.6°, have an impact on thermal resistance of all materials especially for in-situ testing. In addition, resistance change between 0° and the selected tilt angle was found to be in close agreement between the two metrologies for paste-based materials and phase-change material. However, a clear difference in the thermal performance of the tested materials was observed between the two metrologies for the gap filler materials.
ContributorsHarris, Enisa (Author) / Phelan, Patrick (Thesis advisor) / Calhoun, Ronald (Committee member) / Devasenathipathy, Shankar (Committee member) / Arizona State University (Publisher)
Created2011
Description
Modern day gas turbine designers face the problem of hot mainstream gas ingestion into rotor-stator disk cavities. To counter this ingestion, seals are installed on the rotor and stator disk rims and purge air, bled off from the compressor, is injected into the cavities. It is desirable to reduce the supply of purge air as this decreases the net power output as well as efficiency of the gas turbine. Since the purge air influences the disk cavity flow field and effectively the amount of ingestion, the aim of this work was to study the cavity velocity field experimentally using Particle Image Velocimetry (PIV). Experiments were carried out in a model single-stage axial flow turbine set-up that featured blades as well as vanes, with purge air supplied at the hub of the rotor-stator disk cavity. Along with the rotor and stator rim seals, an inner labyrinth seal was provided which split the disk cavity into a rim cavity and an inner cavity. First, static gage pressure distribution was measured to ensure that nominally steady flow conditions had been achieved. The PIV experiments were then performed to map the velocity field on the radial-tangential plane within the rim cavity at four axial locations. Instantaneous velocity maps obtained by PIV were analyzed sector-by-sector to understand the rim cavity flow field. It was observed that the tangential velocity dominated the cavity flow at low purge air flow rate, its dominance decreasing with increase in the purge air flow rate. Radially inboard of the rim cavity, negative radial velocity near the stator surface and positive radial velocity near the rotor surface indicated the presence of a recirculation region in the cavity whose radial extent increased with increase in the purge air flow rate. Qualitative flow streamline patterns are plotted within the rim cavity for different experimental conditions by combining the PIV map information with ingestion measurements within the cavity as reported in Thiagarajan (2013).
ContributorsPathak, Parag (Author) / Roy, Ramendra P (Thesis advisor) / Calhoun, Ronald (Committee member) / Lee, Taewoo (Committee member) / Arizona State University (Publisher)
Created2013
Description
ABSTRACT A vortex tube is a device of a simple structure with no moving parts that can be used to separate a compressed gas into a hot stream and a cold stream. Many studies have been carried out to find the mechanisms of the energy separation in the vortex tube. Recent rapid development in computational fluid dynamics is providing a powerful tool to investigate the complex flow in the vortex tube. However various issues in these numerical simulations remain, such as choosing the most suitable turbulent model, as well as the lack of systematic comparative analysis. LES model for the vortex tube simulation is hardly used in the present literatures, and the influence of parameters on the performance of the vortex tube has scarcely been studied. This study is aimed to find the influence of various parameters on the performance of the vortex tube, the best geometric value of vortex tube and the realizable method to reach the required cold out flow rate 40 kg/s . First of all, setting up an original 3-D simulation vortex tube model. By comparing experiment results reported in the literature and our simulation results, a most suitable model for the simulation of the vortex tube is obtained. Secondly, we perform simulations to optimize parameters that can deliver a set of desired output, such as cold stream pressure, temperature and flow-rate. We also discuss the use of the cold air flow for petroleum engineering applications.
ContributorsCang, Ruijin (Author) / Chen, Kangping (Thesis advisor) / Huang, Hueiping (Committee member) / Calhoun, Ronald (Committee member) / Arizona State University (Publisher)
Created2013
Description
Background: Adequate consumption of fruit and vegetables has been shown to prevent chronic diseases, such as cardiovascular disease, high blood pressure, and type two diabetes. The majority of Americans still consume inadequate daily servings of fruit and vegetables, which include women. Inadequate consumption of fruit and vegetables can be contributed to multiple barriers that hinder consumption in both urban and non-urban areas. The Special Supplemental Nutrition Program for Women, Infant, and Children (WIC) has been shown to positively influence fruit and vegetable consumption by providing healthy foods, such as fruit and vegetables. This study aims to compare the fruit and vegetable consumption of WIC and non-WIC participants between urban and non-urban Rural-Urban Commuting Area (RUCA) codes. Methods: This study was a cross-sectional, secondary analysis of a single time point from the Snuggle Bug/Acurrucadito Study, which had a sample size of (n=53) participants. The participants were separated into two groups, WIC participants, and non-WIC participants, and then further divided based on their respected RUCA code for comparison purposes. The assessment of fruit and vegetable consumption assessment derived from the participant’s 3-day food record. Results: The average consumption of fruit and vegetable consumption among participants was 3.8±2.5 servings There was an inverse relationship between WIC participation and fruit and vegetable consumption among all categories (fruit no juice -0.79, vegetables -0.32, vegetables no potato -0.32, fruit no juice and vegetables -1.1, and fruit no juice and vegetables no potato -1.1). However, none of the results were considered statistically significant. In addition, our study was unable to identify an association between fruit and vegetable consumption and locale due to the small sample size. Conclusions: There was no link observed between fruit and vegetable consumption and WIC participation. Further research of high quality is needed to confirm the relationship between fruit and vegetable consumption of WIC and non-WIC participants in urban and non-urban populations.
ContributorsOrtiz, Steven Michael (Author) / Bruening, Meg (Thesis advisor) / Whisner, Corrie (Committee member) / Shepard, Christina (Committee member) / Arizona State University (Publisher)
Created2022
Description
Purpose: Although numerous studies exist regarding the health impact of the Special, Supplemental Program for Women, Infants and Children (WIC) and the Supplemental Nutrition Assistance Program (SNAP) on their participants’, limited studies have examined how participation in one federal nutrition assistance program, may impact participation or perceived benefit of the other. This study aimed to examine how SNAP participation may impact weight-related pregnancy outcomes and participation of pregnant WIC participants. Methods: The present study is a cross-sectional, secondary data analysis of data available from the Arizona Department of Health Services. A total of 35,659 pregnant woman participated in the Arizona WIC program during 2018 and were included in the study. Pregnant participants were assigned to Group WIC or Group WIC+SNAP respectively. Data was aggregated to the clinic level and clinics with less than 10 pregnant participants were combined for a total of 101 clinics included in the analysis. Weight-related pregnancy outcomes measures included average pre-pregnancy weight, average gestational weight gain, BMI class, and delivery weight. Participation indicator outcomes included average number of visits during pregnancy, timing of first prenatal and postnatal WIC appointment, and entry into WIC within the first trimester. Race, ethnicity, language, and education were also analyzed.
Results: This study found average pre-pregnancy weight was statistically significant for women in group SNAP+WIC weighing 2.8 kg more than women in group WIC(p<0.001). Group WIC had a lower delivery weight average (p<0.001) and a higher amount of women beginning pregnancy with a normal BMI (p=0.004). Group WIC participants were statistically more likely to not enroll in WIC during the first trimester compared with Group WIC+SNAP (p=0.049). Group WIC was more likely to enroll in the 8th (p=0.045) and 9th month (p=0.009) of pregnancy and attend their first postpartum visit 6 months after delivery (p=0.007) as compared to Group WIC+SNAP.
Conclusions: This study found that pregnant WIC participants, not enrolled in SNAP have a lower pre-pregnancy weight and are more likely not to enroll within the first trimester. Future research should focus on individualized characteristics of WIC participants to further improve prenatal and postnatal support.
ContributorsStolworthy, Alexandra (Author) / Bruening, Meg (Thesis advisor) / Wadhera, Devina (Committee member) / Whisner, Corrie (Committee member) / Arizona State University (Publisher)
Created2022
Description
Background: The Special Supplemental Nutrition Program for Women, Infant andChildren (WIC) provides participants with a supplemental food package that follows the
Dietary Guidelines for Americans (DGA’s). The WIC food package has been shown to
improve the diet quality and overall health status of WIC participants. Since the 2009
WIC food package revision, standard issuance of 1% or fat-free milk has been practiced
for participants 24 months or older. Improving the value that participants have on the
WIC foods can be an effective method to improve redemption of WIC foods and improve
overall participation. The aim of this study was to examine if allowing issuance of 2%
milk when clients refuse issuance of 1% or skim milk would affect benefit redemption of
milk and other WIC foods. The study also examined how providing clarification through
training on policy change for issuance of 2% milk would improve staff and director
knowledge of this change in policy.
Methods: This study was an observational, longitudinal study that used linear regression
analysis of aggregated data at the local agency-level from the Arizona WIC program.
Redemption data were analyzed using the Arizona WIC Health and Nutrition Delivery
System (HANDS) at three different intervals throughout the study. The three months
prior to the policy introduction (March-May 2020), redemption after policy introduction
(July-September 2020), and redemption after policy clarification with 2% milk policy
trainings (December 2020-February 2021). Redemption was measured as benefits issued
versus benefits redeemed. Two separate surveys were delivered (via Qualtrics) to the 18
local agency directors (n=18) and their staff members (n=287). These surveys were used
for descriptive purposes.
Results: The results of this study found that there was a decrease in redemption of 2%
milk and all foods at the post intervention stage of the study. WIC staff were found to
have a better understanding of policy to issue 2% milk. Conclusion: Although these
findings are consistent with other current research, further research is needed to examine
how changing policy on current food restrictions placed on WIC foods affects redemption
and how this may improve overall participation.
ContributorsZacarias, Ivan (Author) / Bruening, Meg (Thesis advisor) / Reifsnider, Elizabeth (Committee member) / Whisner, Corrie (Committee member) / Arizona State University (Publisher)
Created2022
The Association Between Time to Eat and Students Fruit & Vegetable Consumption, Selection, and Waste
Description
Background: Studies have examined student fruit/vegetable (FV) consumption, selection, and waste related to lunch duration and found that longer duration at lunch was associated with greater consumption, selection, and reduced waste. However, few studies have investigated the relationship between time to eat and FVs. The aim of this research is to analyze the relationship between objective time to students took to eat (“time to eat”) as it relates to their fruit and vegetable consumption, selection, and plate waste.in elementary, middle, and high schools. Methods: A secondary analysis of cross-sectional study of 37 Arizona schools to discover the differences in the selection, consumption, and waste of FVs from students (Full N = 2226, Elementary N = 630, Middle School N = 699, High School N = 897) using objective time to eat measures. Zero-inflated negative binomial regressions examined differences in FV grams selected, consumed, and wasted adjusted for sociodemographics including race, ethnicity, eligibility for free or reduced lunch, academic year, and sex and clustering for students within schools. Results are presented across school level (elementary, middle, and high school).
Results: The average time taken to eat ranged from 10-12 minutes for all students. The association of time to eat and lunch duration were not closely related (r=0.03, p = 0.172). In the count model for every additional minute spent, there was a 0.5% greater likelihood of selecting FVs for elementary kids among those who took any FVs. In the zero-inflated model, it was found that there was a statistically significant relationship between time spent eating and the selection of fruits and vegetables. For the total sample and high schoolers, a minute more of eating time was associated with a 4.3% and 8.8% greater odds of selecting FV. This means that longer eating time increased the likelihood of choosing fruits and vegetables. The results indicated that the longer students took to eat, the higher the likelihood of consuming more of FVs. Each 10 more minutes spent eating (i.e., time to eat) is associated with a 5% increase in grams of FV selected relative to mean (for those that chose FV) over 1 week this equates to 32 g increase of FV selected. However, for middle schoolers, the time to eat was not found to be significant in relation to the grams of fruits and vegetables consumed. There was some significance in the sociodemographic factors such as gender (all) and other (middle school). There was a relationship between time taken to eat and waste as a proportion for fruits and vegetables. For example, among those among the students who wasted something (as a proportion of selection), each additional 10 minutes of eating time was associated with a .6% decrease in waste relative to the mean (for those who chose fruits and vegetables) over a week, resulting in a decrease in waste percentage of 16.5%. Among high schoolers, males had a slightly higher odds of wasting a proportion of fruits and vegetables.
Conclusions: This study aimed to examine the association between the time students take to eat during lunch and their fruit and vegetable (FV) consumption, selection, and plate waste. The findings revealed that the time to eat was related to FV consumption, depending on the school level. However, it was not significantly associated with FV selection or waste. The study emphasized the need for further research on time to eat, distinguishing it from the duration of lunch. Longer lunch periods and adequate time could influence better food choices, increased FV consumption, and reduced waste. The study highlighted the importance of interventions and school policies promoting healthier food choices and providing sufficient time for students to eat. Future research should validate these findings and explore the impact of socialization opportunities on promoting healthier eating habits. Understanding the relationship between lunch duration, time to eat, and students' dietary behaviors can contribute to improved health outcomes and inform effective strategies in school settings.
ContributorsDandridge, Christina Marie (Author) / Adams, Marc (Thesis advisor) / Whisner, Corrie (Committee member) / Bruening, Meg (Committee member) / Arizona State University (Publisher)
Created2023
Description
According to Our World in Data, the industry sector contributes approximately 5.2 percent of the world's greenhouse gas emissions in 2016 [1]. Of that percentage, the cement industry contributes approximately 3 percent, thus accounting for more than 57 percent of all greenhouse gas emissions within the industry sector. Industrial-scale heating that is powered by renewable energy sources has the potential to combat this issue. This paper aims to analyze and model the Reverse Brayton Cycle to be used as a heat pump in a novel cement production system. The Simple Reverse Brayton Cycle and its potential concerning performance indicators such as coefficient of performance and scalability are determined. A Regenerative Brayton cycle is modeled in MATLAB® programming in order to be optimized and compared to conventional processes that require higher temperatures. Traditional manufacturing methods are discussed. Furthermore, possible methods of improvement are explored to view its effect on performance and temperatures between stages within the cycle.
ContributorsRivera, Daniel E (Author) / Phelan, Patrick (Thesis advisor) / Milcarek, Ryan (Committee member) / Calhoun, Ronald (Committee member) / Arizona State University (Publisher)
Created2024