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- Creators: Arizona State University
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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
There has been a push to create and implement school wellness policies. Childhood obesity statistics suggest that schools may have an important role to play in promoting wellness. Childhood obesity has become a significant problem in the United States. The percentage of obese children in the United States has more than doubled since 1970, and up to 33% of the children in the United States are currently overweight. Among the 33% of children who are overweight, 25% are obese, and 14% have type 2 diabetes, previously considered to be a condition found only in adults. This mixed-method study with a string qualitative component study examined three aspects of federally mandated local wellness polices. The study investigated the policies themselves, how the policies are understood in the local school setting, with a particular focus on the impact the policies have had on school meals. The bulk of the research data was generated through 8 in-depth interviews. The interviews were conducted with key stakeholders within 2 elementary school districts in Arizona. In addition, the evaluation of 20 local wellness polices was conducted via a rubric scoring system. The primary component found to be lacking in local wellness policies was the evaluation method. Recommendations for school districts include the establishment of a clear method of measurement.
ContributorsCrawford, Sara S (Author) / Mccarty, Teresa L. (Thesis advisor) / Molnar, Alex (Thesis advisor) / Montoya, Araceli (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
Parents die during the lives of their children. If the child is an adolescent, that death will impact the student's education immediately or in subsequent years. Findings show the death of a mother does impact the daughter's education. It is imperative educators are willing to work with the student at the time the death occurs as well as in the ensuing months. Seidman's (2006) three-interview format was used as a template for the interviews of 11 women, ranging in age from 19 to 78 and whose mothers died when the women were adolescents. The interviews were primarily conducted in one sitting, transcribed, and then analyzed for common themes that connected to the research on the topic. Those themes include grieving, the role of caring in education, the role of teacher as the second mother, mother-daughter relationships, and the impact of parent death on schooling. These themes from the data cross cut with thematic strands within the study's theoretical framework: the nurturing and empathetic role of the mother, a desire of the daughter not to be different, and the ethics of caring. Findings in this study reveal that the negative impacts of mother loss are felt in diffuse ways, such as a lack of academic or emotional encouragement. Many women discussed the need and availability of support groups including groups at colleges. One practical implication of these findings is schools need to become caring communities in which caring is the norm for all students and teachers, thereby providing all students with needed support in times of crisis. The implications for further research include the impact of the mother death on the education of daughters, how volunteering with an organization related to the cause of the mother's death assists the daughter and types of programs most important to a student's success in post-secondary education. Adolescents are in a time of great change in their lives, and for a daughter, the loss of a mother has an everlasting, life-changing impact.
ContributorsRatti, Theresa Helen McLuskey (Author) / Mccarty, Teresa L (Thesis advisor) / Fischman, Gustavo E. (Committee member) / Powers, Jeanne M. (Committee member) / Arizona State University (Publisher)
Created2011
Description
The purpose of this study was to examine compulsory schooling in the United States and its potential to provide an inconsistent avenue to employment for students from neighborhoods of differing socioeconomic status. Specifically, this study asked why do students from privileged neighborhoods typically end up in positions of ownership and management while those from impoverished urban or rural neighborhoods end up in working-class positions or involved in cycles of incarceration and poverty? This research involved the use of qualitative methods, including participant observation and interview, as well as photography, to take a look at a reputable private day school in the southwest. Data was collected over the span of eight weeks and was then analyzed and compared with preexisting data on the schooling experience of students from impoverished urban and rural neighborhoods, particularly data focused on juvenile detention centers. Results showed that compulsory schooling differs in ways that contribute to the preexisting hierarchical class structure. The research suggests that schooling can be detrimental to the future quality of life for students in impoverished neighborhoods, which questions a compulsory school system that exists within the current hierarchical class system.
ContributorsTheodoropoulos, Eftyhia (Author) / Margolis, Eric (Thesis advisor) / Nakagawa, Kathryn (Committee member) / Appleton, Nicholas (Committee member) / Arizona State University (Publisher)
Created2011
Description
This dissertation examines the factors related to the success of host country field offices established by international Non-Governmental Organizations (NGOs). Further, this dissertation examines NGO field office mission success in the context of working with foreign host governments and clients. This dissertation is a case of the field offices of The Nature Conservancy in South and Central America. The principal research aim is to identify the primary factors that are related to success of field offices. Success is identified as a multidimensional concept. A conceptual model for success is developed. The conceptual model derived causal factors from the literature and captured categories of variables such as: (1) managerial tactics and techniques dictated by the NGO and adopted by field office leaders; (2) the distance between cultural features of the host country and those of the country of origin of the field office manager and personnel; and, (3) characteristics of the host country government. The dissertation: (1) utilizes a working definition of NGO drawn from the scholarly literature in the field; (2) describes the role of field offices (located in host countries) in the calculus of "home office" goal achievement; (3) discusses the types of "change"--delivery of goods, delivery of services, changes in behavior, changes in norms or attitudes--that field offices may have and how they differ in the challenges they create for field office managers; and, (4) develops a conceptual definition for success. This dissertation is concerned with the factors associated with success in the international NGO's field office. A model of success predictors is tested in this work. The findings suggest that the field offices mission success may be affected by local culture but this was not an issue for the organization studied. Mission success as perceived by the field seems to be a product of organizational culture. The contribution of the research to academic literature is that this study is both an exploratory and descriptive study of how NGO mission is carried out in the field and the impacts of national and organizational culture on mission success.
ContributorsKraeger, Patsy (Author) / Cayer, N. Joseph (Thesis advisor) / Yoshioka, Carlton A. (Committee member) / Lan, Zhiyong (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
This dissertation examines the performance of various federal departments on the success of their integration of personnel based on race and gender. It determines if there are variations in the success rate and explores the reasons for the variations based on the literature review and data analysis. The data used are federal employee data compiled by the U.S. Office of Personnel Management, Merit System Protection Board, and the Equal Employment Opportunity Commission through use of personnel surveys from 1979 through 2002 and annual reports. The study uses a cross-sectional model to test whether women and minorities in General Schedule grades 13 -15 have benefited from the implementation of Affirmative Action policy in their prospective agency over time. The effect of department size and affirmative action on the success rate of women and minorities was observed. The data shows that women at the GS 13 -15 grades have made significant gains in their participation rates at all of the departments within the study from 1979 - 2002. The gains made by minorities at the GS 13 -15 grades were not at the same rate as women. In several departments, the participation rates were either flat or decreased. The regression model showed that there is a linear relationship between the success of women and the success of minorities at the GS 13 -15 grade levels within federal departments.
ContributorsSaunders, Romona (Author) / Cayer, Joseph (Thesis advisor) / Alozie, Nicholas (Thesis advisor) / Lan, Gerald Z (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