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- Creators: Arizona State University
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
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
Belief affects behavior and rhetoric has the potential to bring about action. This paper is a critical content analysis of the ideology and rhetoric of key Islamist intellectuals and the Islamist organization Hizb ut-Tahrir, as stated on the website http://english.hizbuttahrir.org. The responses of specific Muslim Reformers are also analyzed. The central argument underlying this analysis centers on the notion that such Islamist ideology and its rhetorical delivery could be a significant trigger for the use of violence; interacting with, yet existing independently of, other factors that contribute to violent actions. In this case, a significant aspect of any solution to Islamist rhetoric would require that Muslim Reformers present a compelling counter-narrative to political Islam (Islamism), one that has an imperative to reduce the amount of violence in the region. Rhetoric alone cannot solve the many complicated issues in the region but we must begin somewhere and countering the explicit and implicit calls to violence of political Islamist organizations like Hizb ut-Tahrir seems a constructive step.
ContributorsBoyer, Paul Daniel (Author) / Mean, Lindsey (Thesis advisor) / Waldron, Vincent (Committee member) / Carter, Heather (Committee member) / Arizona State University (Publisher)
Created2010
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
The United States is facing an emerging principal shortage. This study examines an intervention to deliver professional development for assistant principals on their way to becoming principals. The intervention intended to boost their sense of efficacy as if they were principals while creating a supportive community of professionals for ongoing professional learning. The community was designed much like a professional learning community (PLC) with the intent of developing into a community of practice (CoP). The participants were all elementary school assistant principals in a Title I district in a large metropolitan area. The researcher interviewed an expert set of school administrators consisting of superintendents and consultants (and others who have knowledge of what a good principal ought to be) about what characteristics and skills were left wanting in principal applicants. The data from these interviews provided the discussion topics for the intervention. The assistant principals met regularly over the course of a semester and discussed the topics provided by the expert set of school administrators. Participant interaction within the sessions followed conversation protocols. The researcher was also a participant in the group and served as the coordinator. Each session was recorded and transcribed. The researcher used a mixed methods approach to analyze the intervention. Participants were surveyed to measure their efficacy before and after the intervention. The session transcripts were analyzed using open and axial coding. Data showed no statistically significant change in the participants' sense of efficacy. Data also showed the participants became a coalescing community of practice.
ContributorsRichman, Bryan (Author) / Puckett, Kathleen (Thesis advisor) / Smith, Jeffery (Committee member) / Foulger, Teresa (Committee member) / Arizona State University (Publisher)
Created2011
Description
This dissertation explores the rhetorical significance of persecution claims produced by demonstrably powerful publics in contemporary American culture. This ideological criticism is driven by several related research questions. First, how do members of apparently powerful groups (men, whites, and Christians) come to see themselves as somehow unjustly marginalized, persecuted, or powerless? Second, how are these discourses related to the public sphere and counterpublicity? I argue that, despite startling similarities, these texts studied here are best understood not as counterpublicity but as a strategy of containment available to hegemonic publics. Because these rhetorics of persecution often seek to forestall movements toward pluralism and restorative justice, the analysis forwarded in this dissertation offers important contributions to ongoing theoretical discussions in the fields of public sphere theory and critical cultural theory and practical advice for progressive political activism and critical pedagogy.
ContributorsDuerringer, Christopher (Author) / Brouwer, Daniel (Thesis advisor) / Carlson, Cheree (Committee member) / McDonald, Kelly (Committee member) / Arizona State University (Publisher)
Created2011
Deviant bodies resisting online: examining the intersecting realities of women of color in Xbox Live
Description
Employing qualitative methods and drawing from an intersectional framework which focuses on the multiple identities we all embody, this dissertation focuses on oppressions and resistance strategies employed by women of color in Xbox live, an online gaming community. Ethnographic observations and narrative interviewing reveal that women of color, as deviants within the space, face intersecting oppressions in gaming as in life outside the gaming world. They are linguistically profiled within the space based off of how they sound. They have responded with various strategies to combat the discrimination they experience. Some segregate themselves from the larger gaming population and many refuse to purchase games that depict women in a hyper-sexualized manner or that present people of color stereotypically. For others, the solution is to "sit-in" on games and disrupt game flow by 'player-killing' or engage in other 'griefing' activities. I analyze this behavior in the context of Black feminist consciousness and resistance and uncover that these methods are similar to women who employ resistance strategies for survival within the real world.
ContributorsGray, Kishonna (Author) / Anderson, Lisa M. (Thesis advisor) / Cheong, Pauline (Committee member) / Lim, Merlyna (Committee member) / Arizona State University (Publisher)
Created2011
Description
The current study is the first qualitative investigation aimed solely at understanding what it means to communicate conditional forgiveness in serious romantic relationships. Conditional forgiveness is forgiveness that has been offered with the stipulation that the errant behavior cease. It is a provocative topic because some argue genuine forgiveness is not conditional, but recent discoveries that have associated its use with severe transgressions and relational deterioration suggest it is a critical site for investigation. This inductive analysis of open-ended data from 201 anonymous surveys identified both distinctions between and intersections of conditional forgiveness, forgiveness, and reconciliation. A relational dialectics analysis also revealed that reconcilable-irreconcilable was the overarching tension for conditional forgivers and six additional tensions also were also discovered: individual identity-couple identity, safety-risk, certainty-uncertainty, mercy-justice, heart-mind, and expression-suppression. Of particular intrigue, the current analysis supports the previous discovery of implicit conditional forgiveness--suppressing conditions, sometimes in response to physical and substance abuse. Ultimately, the current analysis contributes to the enduring conversation aimed at understanding the communication and pursuit of forgiveness and reconciliation. It addresses one of the basic instincts and paradoxes of existing with others--the balance between vulnerability and protection.
ContributorsKloeber, Dayna Noel (Author) / Waldron, Vincent R. (Thesis advisor) / Kelley, Douglas L. (Committee member) / Kassing, Jeffrey W. (Committee member) / Fisher, Carla L. (Committee member) / Arizona State University (Publisher)
Created2011
Description
This thesis seeks to answer the question: "What do artistic representations add to the dialogue about the U.S.-Mexico border and immigration beyond political rhetoric and popular media portrayals?" Drawing on political communications (as put forth by Edelman and Altheide), socio-political construction (particularly the White Racial Frame put forth by Feagin), and collective memory theory (especially those of Halbwachs and Pollak), this thesis uses a dual-coding, content analysis to examine the linguistic and visual messages disseminated through news media. Then, interviews with and the work of six immigrant artists are examined for their contribution to the information put forth in the news media. This study finds that news reporting bias falls along a continuum from pro-immigration to extreme anti-immigration (labeled "fearful" reporting). The news media skew strongly toward anti-immigration to fearful in bias, and there is no opposite pro-immigration bias. Through observations of artists' work, the study concludes that artistic representations of the border can fill this strongly pro-immigration void on this bias continuum.
ContributorsMcCarty, Kelly Erin (Author) / Téllez, Michelle (Thesis advisor) / Stancliff, Michael (Committee member) / Segura, Joseph (Committee member) / Arizona State University (Publisher)
Created2011