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
Dynamic loading is the term used for one way of optimally loading a transformer. Dynamic loading means the utility takes into account the thermal time constant of the transformer along with the cooling mode transitions, loading profile and ambient temperature when determining the time-varying loading capability of a transformer. Knowing the maximum dynamic loading rating can increase utilization of the transformer while not reducing life-expectancy, delaying the replacement of the transformer. This document presents the progress on the transformer dynamic loading project sponsored by Salt River Project (SRP). A software application which performs dynamic loading for substation distribution transformers with appropriate transformer thermal models is developed in this project. Two kinds of thermal hottest-spot temperature (HST) and top-oil temperature (TOT) models that will be used in the application--the ASU HST/TOT models and the ANSI models--are presented. Brief validations of the ASU models are presented, showing that the ASU models are accurate in simulating the thermal processes of the transformers. For this production grade application, both the ANSI and the ASU models are built and tested to select the most appropriate models to be used in the dynamic loading calculations. An existing application to build and select the TOT model was used as a starting point for the enhancements developed in this work. These enhancements include: Adding the ability to develop HST models to the existing application, Adding metrics to evaluate the models accuracy and selecting which model will be used in dynamic loading calculation Adding the capability to perform dynamic loading calculations, Production of a maximum dynamic load profile that the transformer can tolerate without acceleration of the insulation aging, Provide suitable output (plots and text) for the results of the dynamic loading calculation. Other challenges discussed include: modification to the input data format, data-quality control, cooling mode estimation. Efforts to overcome these challenges are discussed in this work.
ContributorsLiu, Yi (Author) / Tylavksy, Daniel J (Thesis advisor) / Karady, George G. (Committee member) / Ayyanar, Raja (Committee member) / Arizona State University (Publisher)
Created2011
Description
Virtue was a concept of paramount importance in the American founders' republican thought. Without virtue, there could be no liberty, no order, no devotion to the common good, and no republican government. This dissertation examines the concept of virtue at the American founding, particularly virtue in the political thought of Mercy Otis Warren (1728-1814). The most important female intellectual of the Revolutionary generation, Warren wrote passionately about liberty and the beauty of republican ideals. Most important to this study, she consistently advocated the central place of virtue in a free and well-ordered republic. I argue that Warren incorporates three distinct philosophical threads - classical, bourgeois-marketplace, and Christian ideals - in her conception of virtue. I first analyze how Warren uses each of these three threads of virtue throughout her writings. I then examine how she synthesizes these individual threads into a single, cohesive conception of virtue. I argue that Warren consistently merges these ideals into a conception of virtue that she employs to address three pressing political problems of her day: How to motivate reluctant colonists to seek independence; how to check various forms of corruption spreading among the people; and how to counter corruption arising from commercial growth in the new nation. Modern political theorists often argue that these three threads, especially the classical republican and Christian ideals of virtue, are irreconcilable. My analysis shows that to divorce virtue from Christianity in Warren's conception is to rob it of its corrective vigor within republican government. I argue that what Machiavelli and Rousseau wrote out of republican virtue Warren writes back in. In Warren's political thought, virtue serves as the foundation for a stable enduring political system, provides the necessary informal ordering principle for the emerging republic, and offers the means by which the new nation could achieve its millennial destiny.
ContributorsMunsil, Tracy F (Author) / Ball, Terence (Thesis advisor) / Dagger, Richard (Thesis advisor) / Crittenden, William J. (Committee member) / Arizona State University (Publisher)
Created2011
Description
Emission of CO2 into the atmosphere has become an increasingly concerning issue as we progress into the 21st century Flue gas from coal-burning power plants accounts for 40% of all carbon dioxide emissions. The key to successful separation and sequestration is to separate CO2 directly from flue gas (10-15% CO2, 70% N2), which can range from a few hundred to as high as 1000°C. Conventional microporous membranes (carbons/silicas/zeolites) are capable of separating CO2 from N2 at low temperatures, but cannot achieve separation above 200°C. To overcome the limitations of microporous membranes, a novel ceramic-carbonate dual-phase membrane for high temperature CO2 separation was proposed. The membrane was synthesized from porous La0.6Sr0.4Co0.8Fe0.2O3-d (LSCF) supports and infiltrated with molten carbonate (Li2CO3/Na2CO3/K2CO3). The CO2 permeation mechanism involves a reaction between CO2 (gas phase) and O= (solid phase) to form CO3=, which is then transported through the molten carbonate (liquid phase) to achieve separation. The effects of membrane thickness, temperature and CO2 partial pressure were studied. Decreasing thickness from 3.0 to 0.375 mm led to higher fluxes at 900°C, ranging from 0.186 to 0.322 mL.min-1.cm-2 respectively. CO2 flux increased with temperature from 700 to 900°C. Activation energy for permeation was similar to that for oxygen ion conduction in LSCF. For partial pressures above 0.05 atm, the membrane exhibited a nearly constant flux. From these observations, it was determined that oxygen ion conductivity limits CO2 permeation and that the equilibrium oxygen vacancy concentration in LSCF is dependent on the partial pressure of CO2 in the gas phase. Finally, the dual-phase membrane was used as a membrane reactor. Separation at high temperatures can produce warm, highly concentrated streams of CO2 that could be used as a chemical feedstock for the synthesis of syngas (H2 + CO). Towards this, three different membrane reactor configurations were examined: 1) blank system, 2) LSCF catalyst and 3) 10% Ni/y-alumina catalyst. Performance increased in the order of blank system < LSCF catalyst < Ni/y-alumina catalyst. Favorable conditions for syngas production were high temperature (850°C), low sweep gas flow rate (10 mL.min-1) and high methane concentration (50%) using the Ni/y-alumina catalyst.
ContributorsAnderson, Matthew Brandon (Author) / Lin, Jerry (Thesis advisor) / Alford, Terry (Committee member) / Rege, Kaushal (Committee member) / Anderson, James (Committee member) / Rivera, Daniel (Committee member) / Arizona State University (Publisher)
Created2011
Description
This thesis pursues a method to deregulate the electric distribution system and provide support to distributed renewable generation. A locational marginal price is used to determine prices across a distribution network in real-time. The real-time pricing may provide benefits such as a reduced electricity bill, decreased peak demand, and lower emissions. This distribution locational marginal price (D-LMP) determines the cost of electricity at each node in the electrical network. The D-LMP is comprised of the cost of energy, cost of losses, and a renewable energy premium. The renewable premium is an adjustable function to compensate `green' distributed generation. A D-LMP is derived and formulated from the PJM model, as well as several alternative formulations. The logistics and infrastructure an implementation is briefly discussed. This study also takes advantage of the D-LMP real-time pricing to implement distributed storage technology. A storage schedule optimization is developed using linear programming. Day-ahead LMPs and historical load data are used to determine a predictive optimization. A test bed is created to represent a practical electric distribution system. Historical load, solar, and LMP data are used in the test bed to create a realistic environment. A power flow and tabulation of the D-LMPs was conducted for twelve test cases. The test cases included various penetrations of solar photovoltaics (PV), system networking, and the inclusion of storage technology. Tables of the D-LMPs and network voltages are presented in this work. The final costs are summed and the basic economics are examined. The use of a D-LMP can lower costs across a system when advanced technologies are used. Storage improves system costs, decreases losses, improves system load factor, and bolsters voltage. Solar energy provides many of these same attributes at lower penetrations, but high penetrations have a detrimental effect on the system. System networking also increases these positive effects. The D-LMP has a positive impact on residential customer cost, while greatly increasing the costs for the industrial sector. The D-LMP appears to have many positive impacts on the distribution system but proper cost allocation needs further development.
ContributorsKiefer, Brian Daniel (Author) / Heydt, Gerald T (Thesis advisor) / Shunk, Dan (Committee member) / Hedman, Kory (Committee member) / Arizona State University (Publisher)
Created2011
Description
A relatively simple subset of nanotechnology - nanofluids - can be obtained by adding nanoparticles to conventional base fluids. The promise of these fluids stems from the fact that relatively low particle loadings (typically <1% volume fractions) can significantly change the properties of the base fluid. This research explores how low volume fraction nanofluids, composed of common base-fluids, interact with light energy. Comparative experimentation and modeling reveals that absorbing light volumetrically (i.e. in the depth of the fluid) is fundamentally different from surface-based absorption. Depending on the particle material, size, shape, and volume fraction, a fluid can be changed from being mostly transparent to sunlight (in the case of water, alcohols, oils, and glycols) to being a very efficient volumetric absorber of sunlight. This research also visualizes, under high levels of irradiation, how nanofluids undergo interesting, localized phase change phenomena. For this, images were taken of bubble formation and boiling in aqueous nanofluids heated by a hot wire and by a laser. Infrared thermography was also used to quantify this phenomenon. Overall, though, this research reveals the possibility for novel solar collectors in which the working fluid directly absorbs light energy and undergoes phase change in a single step. Modeling results indicate that these improvements can increase a solar thermal receiver's efficiency by up to 10%.
ContributorsTaylor, Robert (Author) / Phelan, Patrick E (Thesis advisor) / Adrian, Ronald (Committee member) / Trimble, Steve (Committee member) / Posner, Jonathan (Committee member) / Maracas, George (Committee member) / Arizona State University (Publisher)
Created2011
Description
Historians often characterize first ladies in the Progressive Era as representatives of the last vestiges of Victorian womanhood in an increasingly modern society. This dissertation argues that first ladies negotiated an image of themselves that fulfilled both traditional and modern notions of womanhood. In crafting these images, first ladies constructed images of their celebrity selves that were uniquely modern. Thus, images of first ladies in the Progressive Era show them as modest and feminine but also autonomous, intelligent, and capable. Using the historian Charles Ponce de Leon's research on modern human-interest journalism, I contend that first ladies in the Progressive Era worked with the modern press in a symbiotic relationship. This relationship allowed the press exclusive access to what was, ostensibly, the first lady's private, and therefore authentic, self. By purporting to reveal parts of their private lives in the press, first ladies showed themselves as down-to-earth despite their success and fulfilled by their domestic pursuits despite their compelling public lives. By offering the press exclusive access to their lives, first ladies secured the opportunity to shape specific images of themselves to appeal, as broadly as possible, to their husbands and parties' constituents and the American public. First ladies in the Progressive Era thus acted as political figures by using both public and private, or what historian Catherine Allgor terms, "unofficial spaces" to support and reflect their husbands and parties' political agendas. In examining representations of first ladies in popular magazines and newspapers from 1901 to 1921 in tandem with letters, memoirs, and other personal papers from these women, a clear pattern emerges. Despite personal differences, first ladies in the Progressive Era represented themselves according to a specific formula in the modern press. The images, constructed by first ladies in this time period, reflect shifts in economic, social, and political life in Progressive Era America, which called for women to be independent and intelligent yet still maintain their femininity and domesticity.
ContributorsHorohoe, Jill (Author) / Gullett, Gayle (Thesis advisor) / Longley, Rodney K (Committee member) / Warren-Findley, Jannelle (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
The following dissertation provides perspectives on the social, political, economic, and academic influences on language use, and particularly heritage language use, within the Filipino American community. What is the nature of language in this community? In what ways does language exist or co-exist? The hypothesis that autochthonous Filipino languages in the United States cease to be spoken in favor of English by Filipino Americans was tested through mixed methods of research. Literature and databases were reviewed which provided information concerning statistics, issues, and policies relating to language in Filipino America. Field research and interviews were conducted in which language use was of key interest. Results varied individually and contextually. Language seems to exist within the Filipino American community on a dynamic continuum. Immigrant Filipino Americans appear to be bilingual and multilingual. Second generation Filipino Americans tend to be English dominant with a range of bilingualism. The California Department of Education (CDOE) appears to foster bilingualism / multilingualism through its World Languages Departments (secondary education level), by offering language courses, such as Tagalog-based Filipino. Efforts to maintain non-English, Filipino languages in Arizona are less conspicuous, but they do exist primarily in familial and entrepreneurial ways.
ContributorsAxel, Joseph (Author) / Mccarty, Teresa (Thesis advisor) / Wiley, Terrence (Committee member) / Faltis, Christian (Committee member) / Arizona State University (Publisher)
Created2011
Description
Since the 1988 uprising, a transnational advocacy network has formed around the issue of democracy and human rights in Burma. Within this transnational advocacy network, personal narratives of trauma have been promulgated in both international and oppositional news media and human rights reports. My thesis critically analyzes the use of the trauma narrative for advocacy purposes by the transnational advocacy network that has emerged around Burma and reveals the degree to which these narratives adhere to a Western, individualistic meta-narrative focused on political and civil liberties. Examining the "boomerang" pattern and the concept of marketability of movements, I highlight the characteristics of the 1988 uprising and subsequent opposition movement that attracted international interest. Reflecting on the psychological aspects of constructing trauma narratives, I then review the scholarship which links trauma narratives to social and human rights movements. Using a Foucauldian approach to discourse analysis, I subsequently explain my methodology in analyzing the personal narratives I have chosen. Beyond a theoretical discussion of trauma narratives and transnational advocacy networks, I analyze the use of personal narratives of activists involved in the 1988 uprising and the emergence of Aung San Suu Kyi's life story as a compelling narrative for Western audiences. I then explore the structure of human rights reports which situate personal narratives of trauma within the framework of international human rights law. I note the differences in the construction of traumatic narratives of agency and those of victimization. Finally, using Cyclone Nargis as a case study, I uncover the discursive divide between human rights and humanitarian actors and their use of personal narratives to support different discursive constructions of the aid effort in the aftermath of the cyclone. I conclude with an appeal to a more reflexive approach to advocacy work reliant on trauma narratives and highlight feminist methodologies that have been successful in bringing marginalized narratives to the center of human rights discussions.
ContributorsBynum, Kate Elliott (Author) / Stancliff, Michael (Thesis advisor) / Friedrich, Patricia (Committee member) / Vaughan, Suzanne (Committee member) / Arizona State University (Publisher)
Created2011