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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Description
Emergent environmental issues, ever-shrinking petroleum reserves, and rising fossil fuel costs continue to spur interest in the development of sustainable biofuels from renewable feed-stocks. Meanwhile, however, the development and viability of biofuel fermentations remain limited by numerous factors such as feedback inhibition and inefficient and generally energy intensive product recovery processes. To circumvent both feedback inhibition and recovery issues, researchers have turned their attention to incorporating energy efficient separation techniques such as adsorption in in situ product recovery (ISPR) approaches. This thesis focused on the characterization of two novel adsorbents for the recovery of alcohol biofuels from model aqueous solutions. First, a hydrophobic silica aerogel was evaluated as a biofuel adsorbent through characterization of equilibrium behavior for conventional second generation biofuels (e.g., ethanol and n-butanol). Longer chain and accordingly more hydrophobic alcohols (i.e., n-butanol and 2-pentanol) were more effectively adsorbed than shorter chain alcohols (i.e., ethanol and i-propanol), suggesting a mechanism of hydrophobic adsorption. Still, the adsorbed alcohol capacity at biologically relevant conditions were low relative to other `model' biofuel adsorbents as a result of poor interfacial contact between the aqueous and sorbent. However, sorbent wettability and adsorption is greatly enhanced at high concentrations of alcohol in the aqueous. Consequently, the sorbent exhibits Type IV adsorption isotherms for all biofuels studied, which results from significant multilayer adsorption at elevated alcohol concentrations in the aqueous. Additionally, sorbent wettability significantly affects the dynamic binding efficiency within a packed adsorption column. Second, mesoporous carbons were evaluated as biofuel adsorbents through characterization of equilibrium and kinetic behavior. Variations in synthetic conditions enabled tuning of specific surface area and pore morphology of adsorbents. The adsorbed alcohol capacity increased with elevated specific surface area of the adsorbents. While their adsorption capacity is comparable to polymeric adsorbents of similar surface area, pore morphology and structure of mesoporous carbons greatly influenced adsorption rates. Multiple cycles of adsorbent regeneration rendered no impact on adsorption equilibrium or kinetics. The high chemical and thermal stability of mesoporous carbons provide potential significant advantages over other commonly examined biofuel adsorbents. Correspondingly, mesoporous carbons should be further studied for biofuel ISPR applications.
ContributorsLevario, Thomas (Author) / Nielsen, David R (Thesis advisor) / Vogt, Bryan D (Committee member) / Lind, Mary L (Committee member) / Arizona State University (Publisher)
Created2011
Description
ABSTRACT There is a body of literature--albeit largely from the UK and Australia--that examines the ways in which class and gender influence life course, including educational attainment; however, much of this literature offers explanations and analyses for why individuals choose the life course they do. By assuming a cause-effect relationship between class and gender and life course, these studies perpetuate the idea that life can be predicted and controlled. Such an approach implies there is but one way of viewing--or an "official reading" of--the experience of class and gender. This silences other readings. This study goes beneath these "interpretations" and explores the phenomenon of identity and identity making in women who grew up working-class. Included is an investigation into how these women recognize and participate in their own identity making, identifying the interpretations they created and apply to their experience and the ways in which they juxtapose their educative experience. Using semi-structured interview I interviewed 21 women with working-class habitués. The strategy of inquiry that corresponded best to the goal of this project was heuristics, a variant of empathetic phenomenology. Heuristics distinguishes itself by including the life experience of the researcher while still showing how different people may participate in an event in their lives and how these individuals may give it radically different meanings. This has two effects: (1) the researcher recognizes that their own life experience affects their interpretations of these stories and (2) it elucidates the researcher's own life as it relates to identity formation and educational experience. Two, heuristics encourages different ways of presenting findings through a variety of art forms meant to enhance the immediacy and impact of an experience rather than offer any explanation of it. As a result of the research, four themes essential to locating the experience of women who grew up working class were discovered: making, paying attention, taking care, and up. These themes have pedagogic significance as women with working-class habitués navigate from this social space: the downstream effect of which is how and what these women take up as education.
ContributorsDecker, Shannon Irene (Author) / Blumenfeld-Jones, Donald (Thesis advisor) / Richards-Young, Gillian (Committee member) / Sandlin, Jennifer (Committee member) / Arizona State University (Publisher)
Created2011
A bilingual, bicultural interpreter and researcher navigates blurry boundaries and intersectionality
Description
A researcher reflects using a close reading of interview transcripts and description to share what happened while participating in multiple roles in a larger ethnographic study of the acculturation process of deaf students in kindergarten classrooms in three countries. The course of this paper will focus on three instances that took place in Japan and America. The analysis of these examples will bring to light the concept of taking on multiple roles, including graduate research assistant, interpreter, cultural mediator, and sociolinguistic consultant within a research project serving to uncover challenging personal and professional dilemmas and crossing boundaries; the dual roles, interpreter and researcher being the primary focus. This analysis results in a brief look at a thought provoking, yet evolving task of the researcher/interpreter. Maintaining multiple roles in the study the researcher is able to potentially identify and contribute "hidden" knowledge that may have been overlooked by other members of the research team. Balancing these different roles become key implications when interpreting practice, ethical boundaries, and participant research at times the lines of separation are blurred.
ContributorsHensley, Jennifer Scarboro (Author) / Tobin, Joseph (Thesis advisor) / Artiles, Alfredo (Committee member) / Horejes, Thomas (Committee member) / Arizona State University (Publisher)
Created2011
Description
Proton exchange membrane fuel cells (PEMFCs) run on pure hydrogen and oxygen (or air), producing electricity, water, and some heat. This makes PEMFC an attractive option for clean power generation. PEMFCs also operate at low temperature which makes them quick to start up and easy to handle. PEMFCs have several important limitations which must be overcome before commercial viability can be achieved. Active areas of research into making them commercially viable include reducing the cost, size and weight of fuel cells while also increasing their durability and performance. A growing and important part of this research involves the computer modeling of fuel cells. High quality computer modeling and simulation of fuel cells can help speed up the discovery of optimized fuel cell components. Computer modeling can also help improve fundamental understanding of the mechanisms and reactions that take place within the fuel cell. The work presented in this thesis describes a procedure for utilizing computer modeling to create high quality fuel cell simulations using Ansys Fluent 12.1. Methods for creating computer aided design (CAD) models of fuel cells are discussed. Detailed simulation parameters are described and emphasis is placed on establishing convergence criteria which are essential for producing consistent results. A mesh sensitivity study of the catalyst and membrane layers is presented showing the importance of adhering to strictly defined convergence criteria. A study of iteration sensitivity of the simulation at low and high current densities is performed which demonstrates the variance in the rate of convergence and the absolute difference between solution values derived at low numbers of iterations and high numbers of iterations.
ContributorsArvay, Adam (Author) / Madakannan, Arunachalanadar (Thesis advisor) / Peng, Xihong (Committee member) / Liang, Yong (Committee member) / Subach, James (Committee member) / Arizona State University (Publisher)
Created2011
Description
Infant mortality rate of field deployed photovoltaic (PV) modules may be expected to be higher than that estimated by standard qualification tests. The reason for increased failure rates may be attributed to the high system voltages. High voltages (HV) in grid connected modules induce additional stress factors that cause new degradation mechanisms. These new degradation mechanisms are not recognized by qualification stress tests. To study and model the effect of high system voltages, recently, potential induced degradation (PID) test method has been introduced. Using PID studies, it has been reported that high voltage failure rates are essentially due to increased leakage currents from active semiconducting layer to the grounded module frame, through encapsulant and/or glass. This project involved designing and commissioning of a new PID test bed at Photovoltaic Reliability Laboratory (PRL) of Arizona State University (ASU) to study the mechanisms of HV induced degradation. In this study, PID stress tests have been performed on accelerated stress modules, in addition to fresh modules of crystalline silicon technology. Accelerated stressing includes thermal cycling (TC200 cycles) and damp heat (1000 hours) tests as per IEC 61215. Failure rates in field deployed modules that are exposed to long term weather conditions are better simulated by conducting HV tests on prior accelerated stress tested modules. The PID testing was performed in 3 phases on a set of 5 mono crystalline silicon modules. In Phase-I of PID test, a positive bias of +600 V was applied, between shorted leads and frame of each module, on 3 modules with conducting carbon coating on glass superstrate. The 3 module set was comprised of: 1 fresh control, TC200 and DH1000. The PID test was conducted in an environmental chamber by stressing the modules at 85°C, for 35 hours with an intermittent evaluation for Arrhenius effects. In the Phase-II, a negative bias of -600 V was applied on a set of 3 modules in the chamber as defined above. The 3 module set in phase-II was comprised of: control module from phase-I, TC200 and DH1000. In the Phase-III, the same set of 3 modules which were used in the phase-II again subjected to +600 V bias to observe the recovery of lost power during the Phase-II. Electrical performance, infrared (IR) and electroluminescence (EL) were done prior and post PID testing. It was observed that high voltage positive bias in the first phase resulted in little
o power loss, high voltage negative bias in the second phase caused significant power loss and the high voltage positive bias in the third phase resulted in major recovery of lost power.
o power loss, high voltage negative bias in the second phase caused significant power loss and the high voltage positive bias in the third phase resulted in major recovery of lost power.
ContributorsGoranti, Sandhya (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Rogers, Bradley (Committee member) / Macia, Narciso (Committee member) / Arizona State University (Publisher)
Created2011
Description
Building Applied Photovoltaics (BAPV) form an essential part of today's solar economy. This thesis is an effort to compare and understand the effect of fan cooling on the temperature of rooftop photovoltaic (PV) modules by comparing two side-by-side arrays (test array and control array) under identical ambient conditions of irradiance, air temperature, wind speed and wind direction. The lower operating temperature of PV modules due to fan operation mitigates array non uniformity and improves on performance. A crystalline silicon (c-Si) PV module has a light to electrical conversion efficiency of 14-20%. So on a cool sunny day with incident solar irradiance of 1000 W/m2, a PV module with 15% efficiency, will produce about only 150 watts. The rest of the energy is primarily lost in the form of heat. Heat extraction methods for BAPV systems may become increasingly higher in demand as the hot stagnant air underneath the array can be extracted to improve the array efficiency and the extracted low-temperature heat can also be used for residential space heating and water heating. Poly c-Si modules experience a negative temperature coefficient of power at about -0.5% /o C. A typical poly c-Si module would experience power loss due to elevation in temperature, which may be in the range of 25 to 30% for desert conditions such as that of Mesa, Arizona. This thesis investigates the effect of fan cooling on the previously developed thermal models at Arizona State University and on the performance of PV modules/arrays. Ambient conditions are continuously monitored and collected to calculate module temperature using the thermal model and to compare with actually measured temperature of individual modules. Including baseline analysis, the thesis has also looked into the effect of fan on the test array in three stages of 14 continuous days each. Multiple Thermal models are developed in order to identify the effect of fan cooling on performance and temperature uniformity. Although the fan did not prove to have much significant cooling effect on the system, but when combined with wind blocks it helped improve the thermal mismatch both under low and high wind speed conditions.
ContributorsChatterjee, Saurabh (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Rogers, Bradley (Committee member) / Macia, Narciso (Committee member) / Arizona State University (Publisher)
Created2011
Description
Photovoltaic (PV) modules undergo performance degradation depending on climatic conditions, applications, and system configurations. The performance degradation prediction of PV modules is primarily based on Accelerated Life Testing (ALT) procedures. In order to further strengthen the ALT process, additional investigation of the power degradation of field aged PV modules in various configurations is required. A detailed investigation of 1,900 field aged (12-18 years) PV modules deployed in a power plant application was conducted for this study. Analysis was based on the current-voltage (I-V) measurement of all the 1,900 modules individually. I-V curve data of individual modules formed the basis for calculating the performance degradation of the modules. The percentage performance degradation and rates of degradation were compared to an earlier study done at the same plant. The current research was primarily focused on identifying the extent of potential induced degradation (PID) of individual modules with reference to the negative ground potential. To investigate this, the arrangement and connection of the individual modules/strings was examined in detail. The study also examined the extent of underperformance of every series string due to performance mismatch of individual modules in that string. The power loss due to individual module degradation and module mismatch at string level was then compared to the rated value.
ContributorsJaspreet Singh (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Srinivasan, Devarajan (Committee member) / Rogers, Bradley (Committee member) / Arizona State University (Publisher)
Created2011
Description
Masculinity has been increasingly recognized as a critical and relatively unexplored area of inquiry in anthropological gender studies. This project seeks to expand anthropological research on masculinity to contemporary American society. Using the case study of a male-centered popular new sport, Mixed Martial Arts (also known as cagefighting) this project integrates theories of embodiment and feminist perspectives to explore how masculinity and masculine hegemony are shaped, contested, and perpetuated in the United States. Using a multi-level framework this project explores: 1) How is masculinity experienced and expressed by Mixed Martial Arts fighters as a form of self-identity? How do their bodies play a role in constructing masculinity? 2) What are the pervasive forms of masculinity associated with Mixed Martial Arts (MMA)? Are they truly representative of the sport? 3) Can these pervasive forms of masculinity be seen as hegemonic? How would hegemony operate in relation to individual experience? Using multiple methods to capture multiple points of view was critical to thoroughly examining the complex notion of masculinity. This study employed participant observation, semi-structured interviews, focus groups, surveys, photo elicitation, and media content analysis, as each presented particular benefits and allowed for the development a more well-rounded understanding of masculinity within the realm of MMA. This study also situates the rise of MMA and its representations of masculinity within the greater perspective of contemporary American society. By doing so reveals how ideologies of prescribed masculinity do not arise out of a vacuum but in relation to particular economic, social and political contexts. An emphasis of this study was to examine the daily lives of MMA fighters to understand how their participation in what may be regarded as a hypermasculine activity affects their own perceptions of masculinity. In looking at how masculinity is embodied, the gaps and often contradictions between representation and individual experiences are revealed. Ultimately, the goal of this research is to contribute to a better understanding of masculinity as both an embodied and relational construct.
ContributorsHolthuysen, Jaime (Author) / Hjorleifur Jonsson (Thesis advisor) / Tsuda, Takeyuki (Committee member) / Ballestero-Salaverry, Andrea (Committee member) / Arizona State University (Publisher)
Created2011
Description
This study examines the contemporary school placement decisions of Navajo parents in the reservation community of Piñon, Arizona. School placement decisions are defined as the school where the parent chooses to enroll his/her child for schooling. Twelve Navajo parents participated in this qualitative study, which explored their past educational experiences in order to garner insight into the current school placement choices they have made for their children. Navajo parents who live within the community of Piñon, AZ who currently have school-aged children living in their household were recruited to participate in this study. Participants took part in 60- to 90-minute interviews that included questions related to their prior educational experiences and current school placement choices for their children. Parents were given an opportunity to reflect about the school placement decisions they have made for their children. The variety of schools Navajo parents are able to choose from were illuminated. These findings have implications for education decision makers by providing insight into which schools parents are choosing and why. The study will assist Navajo Nation policy makers in future educational planning, and may have more general implications for American Indian/Alaskan Native education. This may assist Navajo Education policy makers in making future decisions regarding the newly developed Navajo Department of Education and its education planning. Participants will also benefit from the study by being able to understand how the past has impacted the school placement choices they have made. In doing so parents may be better able to articulate the impetus behind the choices they make for their children, thereby becoming better advocates for themselves and their children. The results of this study impacts scholarly literature as a new viewpoint in the area of school choice. Navajo parents represent a distinct group who make educational choices within a specific context. This study is unique as the impact of historical Indian education policies is considered. Future studies can further expand on the topic creating a unique area of research in the field of Indian education.
ContributorsLansing, Danielle R (Author) / Mccarty, Teresa L. (Thesis advisor) / Romero-Little, Mary Eunice (Committee member) / Frederick, Dale (Committee member) / Arizona State University (Publisher)
Created2011
Description
Native American communities face an ongoing challenge of effectively addressing cancer health disparities, as well as environmental racism issues that may compound these inequities. This dissertation identified the shared cultural knowledge and beliefs about cancer in a southwest American Indian community utilizing a cultural consensus method, an approach that combines qualitative and quantitative data. A community-based participatory research (CBPR) approach was applied at all stages of the study. The three phases of research that were undertaken included: 1) ethnographic interviews - to identifying the themes or the content of the participants' cultural model, 2A) ranking of themes - to provide an understanding of the relative importance of the content of the cultural model, 2B) pile sorts - identify the organization of items within specific domains, and 3) a community survey - access whether the model is shared in the greater community. The cultural consensus method has not been utilized to date in identifying the collective cultural beliefs about cancer prevention, treatment or survivorship in a Native American community. Its use represents a methodological step forward in two areas: 1) the traditional ethnographic inferences used in identifying and defining cultural meaning as it relates to health can be tested more rigorously than in the past, and 2) it addresses the challenge of providing reliable results based on a small number of community informants. This is especially significant when working with smaller tribal/cultural groups where the small sample size has led to questions concerning the reliability and validity of health-related research. Results showed that the key consultants shared strong agreement or consensus on a cultural model regarding the importance of environmental and lifestyle causes of cancer. However, there was no consensus found among the key consultants on the prevention and treatment of cancer. The results of the community survey indicated agreement or consensus in the sub-domains of descriptions of cancer, risk/cause, prevention, treatment, remission/cure and living with cancer. Identifying cultural beliefs and models regarding cancer could contribute to the effective development of culturally responsive cancer prevention education and treatment programs.
ContributorsClaus, Cynthia (Author) / Koss, Joan (Thesis advisor) / Brandt, Elizabeth, (Thesis advisor) / Joe, Jennie (Committee member) / Maupin, Jonathan (Committee member) / Arizona State University (Publisher)
Created2011