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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
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 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
This research examines the use of innovative mechanisms for encouragement of citizen participation in the governance, policy, and decision making processes using case studies of Washington, DC, the United States and Seoul, South Korea for comparison. The research illustrates ways of encouraging development of citizen participation using innovative mechanisms through comparative study. This research used a comparative case study of the two cities which focuses on how the two governments apply ICTs and foster citizen participation, what similarities and differences there are between the two city governments' performance and practices, and what may cause these similarities and differences. For the research, websites and citizen participation practices of Washington, DC and Seoul using innovative technologies - Citizen Summit and Seoul Oasis - are reviewed and compared using the categories of general capacity, actor, legal aspect, management, and evaluation. As capitals of the United States and South Korea, Washington, DC and Seoul lead the encouragement of citizen participation, and the two cities' specific practices are recognized as exemplary. The findings describe encouragement of citizen participation using innovative technologies in governance, policy, and decision making processes of Washington, DC and Seoul as well as similarities and differences. Both cities commonly use Government 2.0. Through Government 2.0, citizens can participate and influence the results and effects of policy. Also, governments secure transparency, legitimacy, and efficiency through direct communication with citizens. The study illustrates how citizen participation using innovative technologies can support civic engagement in local government. Strong leadership of the mayor is a common driving force of the two cities in initiating and implementing the Citizen Summit and Seoul Oasis. Different contexts of the two cities influence ways to initiate and utilize innovative technologies. Washington, DC implemented a practice combining public meeting and small group discussion using innovative technologies. On the other hand, Seoul initiated a new citizen participation practice based on the Internet. The results of the research show that innovative mechanisms allow adopting new government-citizen relationships in both cities.
ContributorsChung, So Yoon (Author) / Cayer, N. Joseph (Thesis advisor) / Svara, James H. (Committee member) / Lan, Gerald Z (Committee member) / Arizona State University (Publisher)
Created2011
Description
Most of challenges facing today's government cannot be resolved without collaborative efforts from multiple non-state stakeholders, organizations, and active participation from citizens. Collaborative governance has become an important form of management practice. Yet the success of this inclusive management approach depends on whether government agencies and all other involved parties can collectively deliberate and work toward the shared goals. This dissertation examines whether information technology (IT) tools and prior cooperative interactions can be used to facilitate the collaboration process, and how IT tools and prior cooperative interactions can, if at all, get citizens and communities more engaged in collaborative governance. It focuses on the individual and small groups engaged in deliberating on a local community problem, which is water sustainability in the Phoenix metropolitan area. Experiments were conducted to compare how people deliberate and interact with each other under different IT-facilitated deliberation environments and with different prehistory of interactions. The unique experimental site for this research is a designed deliberation space that can seat up to 25 participants surrounded by the immersive 260-degree seven-screen communal display. In total, 126 students from Arizona State University participated in the experiment. The experiment results show that the deliberation spaces can influence participants' engagement in the collaborative efforts toward collective goals. This dissertation demonstrates the great potential of well-designed IT-facilitated deliberation spaces for supporting policy deliberation and advancing collaborative governance. This dissertation provides practical suggestions for public managers and community leaders on how to design and develop the desired features of IT-facilitated interaction environments for face-to-face and computer-mediated online public deliberation activities. This dissertation also discusses lessons and strategies on how to build a stronger sense of community for promoting community-based efforts to achieve collective goals.
ContributorsHu, Qian (Author) / Cayer, N. Joseph (Thesis advisor) / Lan, Zhiyong (Thesis advisor) / Johnston, Erik W., 1977- (Committee member) / Shangraw, Ralph (Committee member) / Arizona State University (Publisher)
Created2011
Description
The electrode-electrolyte interface in electrochemical environments involves the understanding of complex processes relevant for all electrochemical applications. Some of these processes include electronic structure, charge storage, charge transfer, solvent dynamics and structure and surface adsorption. In order to engineer electrochemical systems, no matter the function, requires fundamental intuition of all the processes at the interface. The following work presents different systems in which the electrode-electrolyte interface is highly important. The first is a charge storage electrode utilizing percolation theory to develop an electrode architecture producing high capacities. This is followed by Zn deposition in an ionic liquid in which the deposition morphology is highly dependant on the charge transfer and surface adsorption at the interface. Electrode Architecture: A three-dimensional manganese oxide supercapacitor electrode architecture is synthesized by leveraging percolation theory to develop a hierarchically designed tri-continuous percolated network. The three percolated phases include a faradaically-active material, electrically conductive material and pore-former templated void space. The micropores create pathways for ionic conductivity, while the nanoscale electrically conducting phase provides both bulk conductivity and local electron transfer with the electrochemically active phase. Zn Electrodeposition: Zn redox in air and water stable N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, [C2nmm][NTf2] is presented. Under various conditions, characterization of overpotential, kinetics and diffusion of Zn species and morphological evolution as a function of overpotential and Zn concentration are analyzed. The surface stress evolution during Zn deposition is examined where grain size and texturing play significant rolls in compressive stress generation. Morphological repeatability in the ILs led to a novel study of purity in ionic liquids where it is found that surface adsorption of residual amine and chloride from the organic synthesis affect growth characteristics. The drivers of this work are to understand the processes occurring at the electrode-electrolyte interface and with that knowledge, engineer systems yielding optimal performance. With this in mind, the design of a bulk supercapacitor electrode architecture with excellent composite specific capacitances, as well as develop conditions producing ideal Zn deposition morphologies was completed.
ContributorsEngstrom, Erika (Author) / Friesen, Cody (Thesis advisor) / Buttry, Daniel (Committee member) / Sieradzki, Karl (Committee member) / Arizona State University (Publisher)
Created2011
Description
The uncertainty of change inherent in issues such as climate change and regional growth has created a significant challenge for public decision makers trying to decide what adaptation actions are needed to respond to these possible changes. This challenge threatens the resiliency and thus the long term sustainability of our social-ecological systems. Using an empirical embedded case study approach to explore the application of advanced scenario analysis methods to regional growth visioning projects in two regions, this dissertation provides empirical evidence that for issues with high uncertainty, advanced scenario planning (ASP) methods are effective tools for helping decision makers to anticipate and prepare to adapt to change.
ContributorsQuay, Ray (Author) / Pijawka, David (Thesis advisor) / Shangraw, Ralph (Committee member) / Holway, James (Committee member) / Arizona State University (Publisher)
Created2011