Matching Items (929)
Filtering by

Clear all filters

152030-Thumbnail Image.png
Description
Recently, the use of zinc oxide (ZnO) nanowires as an interphase in composite materials has been demonstrated to increase the interfacial shear strength between carbon fiber and an epoxy matrix. In this research work, the strong adhesion between ZnO and carbon fiber is investigated to elucidate the interactions at the

Recently, the use of zinc oxide (ZnO) nanowires as an interphase in composite materials has been demonstrated to increase the interfacial shear strength between carbon fiber and an epoxy matrix. In this research work, the strong adhesion between ZnO and carbon fiber is investigated to elucidate the interactions at the interface that result in high interfacial strength. First, molecular dynamics (MD) simulations are performed to calculate the adhesive energy between bare carbon and ZnO. Since the carbon fiber surface has oxygen functional groups, these were modeled and MD simulations showed the preference of ketones to strongly interact with ZnO, however, this was not observed in the case of hydroxyls and carboxylic acid. It was also found that the ketone molecules ability to change orientation facilitated the interactions with the ZnO surface. Experimentally, the atomic force microscope (AFM) was used to measure the adhesive energy between ZnO and carbon through a liftoff test by employing highly oriented pyrolytic graphite (HOPG) substrate and a ZnO covered AFM tip. Oxygen functionalization of the HOPG surface shows the increase of adhesive energy. Additionally, the surface of ZnO was modified to hold a negative charge, which demonstrated an increase in the adhesive energy. This increase in adhesion resulted from increased induction forces given the relatively high polarizability of HOPG and the preservation of the charge on ZnO surface. It was found that the additional negative charge can be preserved on the ZnO surface because there is an energy barrier since carbon and ZnO form a Schottky contact. Other materials with the same ionic properties of ZnO but with higher polarizability also demonstrated good adhesion to carbon. This result substantiates that their induced interaction can be facilitated not only by the polarizability of carbon but by any of the materials at the interface. The versatility to modify the magnitude of the induced interaction between carbon and an ionic material provides a new route to create interfaces with controlled interfacial strength.
ContributorsGalan Vera, Magdian Ulises (Author) / Sodano, Henry A (Thesis advisor) / Jiang, Hanqing (Committee member) / Solanki, Kiran (Committee member) / Oswald, Jay (Committee member) / Speyer, Gil (Committee member) / Arizona State University (Publisher)
Created2013
151874-Thumbnail Image.png
Description
Wind measurements are fundamental inputs for the evaluation of potential energy yield and performance of wind farms. Three-dimensional scanning coherent Doppler lidar (CDL) may provide a new basis for wind farm site selection, design, and control. In this research, CDL measurements obtained from multiple wind energy developments are analyzed and

Wind measurements are fundamental inputs for the evaluation of potential energy yield and performance of wind farms. Three-dimensional scanning coherent Doppler lidar (CDL) may provide a new basis for wind farm site selection, design, and control. In this research, CDL measurements obtained from multiple wind energy developments are analyzed and a novel wind farm control approach has been modeled. The possibility of using lidar measurements to more fully characterize the wind field is discussed, specifically, terrain effects, spatial variation of winds, power density, and the effect of shear at different layers within the rotor swept area. Various vector retrieval methods have been applied to the lidar data, and results are presented on an elevated terrain-following surface at hub height. The vector retrieval estimates are compared with tower measurements, after interpolation to the appropriate level. CDL data is used to estimate the spatial power density at hub height. Since CDL can measure winds at different vertical levels, an approach for estimating wind power density over the wind turbine rotor-swept area is explored. Sample optimized layouts of wind farm using lidar data and global optimization algorithms, accounting for wake interaction effects, have been explored. An approach to evaluate spatial wind speed and direction estimates from a standard nested Coupled Ocean and Atmosphere Mesoscale Prediction System (COAMPS) model and CDL is presented. The magnitude of spatial difference between observations and simulation for wind energy assessment is researched. Diurnal effects and ramp events as estimated by CDL and COAMPS were inter-compared. Novel wind farm control based on incoming winds and direction input from CDL's is developed. Both yaw and pitch control using scanning CDL for efficient wind farm control is analyzed. The wind farm control optimizes power production and reduces loads on wind turbines for various lidar wind speed and direction inputs, accounting for wind farm wake losses and wind speed evolution. Several wind farm control configurations were developed, for enhanced integrability into the electrical grid. Finally, the value proposition of CDL for a wind farm development, based on uncertainty reduction and return of investment is analyzed.
ContributorsKrishnamurthy, Raghavendra (Author) / Calhoun, Ronald J (Thesis advisor) / Chen, Kangping (Committee member) / Huang, Huei-Ping (Committee member) / Fraser, Matthew (Committee member) / Phelan, Patrick (Committee member) / Arizona State University (Publisher)
Created2013
151683-Thumbnail Image.png
Description
Este trabajo examina la producción literaria y cultural chicana/méxicosudoesteña de las distintas épocas coloniales del sudoeste: la época colonial española (1521-1821), la época colonial angloamericana (1848-1965) y la época poscolonial (1965-presente) para ver hasta qué punto siguen vigentes los legados coloniales dentro de un contexto contemporáneo. Avanzamos la hipótesis que,

Este trabajo examina la producción literaria y cultural chicana/méxicosudoesteña de las distintas épocas coloniales del sudoeste: la época colonial española (1521-1821), la época colonial angloamericana (1848-1965) y la época poscolonial (1965-presente) para ver hasta qué punto siguen vigentes los legados coloniales dentro de un contexto contemporáneo. Avanzamos la hipótesis que, de la larga residencia histórica y geográfica de las personas hispanomexicanas en el sudoeste, se han producidos textos simbólicos donde se registran dos o más discursos residuos cuyo origen es una ideología dominante. El capítulo 1 plantea y detalla la hipótesis, reseña los numerosos estudios existentes, describe el marco teórico y da la división en capítulos. En el capítulo 2, se da de manera detallada el método crítico: la definición del colonialismo clásico según la teoría de Mario Barrera, la relación colonizador/colonizado aportada por Albert Memmi y los conceptos del tercer espacio híbrido, el mestizaje y el imaginario decolonial asociados con la época poscolonial como ofrecidos respectivamente por Homi Bhabha, Rafael Pérez-Torres y Emma Pérez. El capítulo 3 ofrece un análisis de la época colonial española vía dos obras nuevomexicanas: el poema épico Historia de la Nueva México (1610) de Gaspar Pérez de Villagrá y el drama Los comanches (c.1779) de anónimo. El capítulo 4 trata la colonización angloamericana en las obras The Squatter and the Don (1885) de María Amparo Ruiz de Burton y Dew on the Thorn (escrita en los 1940; publicada en 1997) de Jovita González de Mireles. El capítulo 5 examina la época poscolonial vía la obra Los muertos también cuentan (1995) de Miguel Méndez. Una lectura de la literatura chicana/méxicosudoesteña revela la presencia de varios personajes típicos asociados cada uno a una diferente época histórica desde el conquistador español hasta un mexicano recién inmigrado, quienes no han podido evadir la correspondiente presencia de un grupo dominante u colonizador. Con base en una investigación de las cinco obras seleccionadas, se muestra cómo las relaciones coloniales se forman y se transforman y luego se manifiestan en un contexto contemporáneo, desplazando por ende nuestro entendimiento de las relaciones coloniales como un simple proyecto binario de dominación y subordinación.
ContributorsFonseca, Vanessa (Author) / Hernández-G., Manuel De Jesús (Thesis advisor) / Rosales, Jesus (Committee member) / García-Fernández, Carlos Javier (Committee member) / Volek, Emil (Committee member) / Horan, Elizabeth (Committee member) / Arizona State University (Publisher)
Created2013
151691-Thumbnail Image.png
Description
Set in the former Yugoslavia, contemporary Bosnia and Herzegovina, and Midwest America, the collection of short stories follows the complicated trajectory of war-survivor to refugee and, then, immigrant. These stories---about religious prisoners who are not at all religious, about young, philosophizing boys tempting the bullets of snipers, about men retracing

Set in the former Yugoslavia, contemporary Bosnia and Herzegovina, and Midwest America, the collection of short stories follows the complicated trajectory of war-survivor to refugee and, then, immigrant. These stories---about religious prisoners who are not at all religious, about young, philosophizing boys tempting the bullets of snipers, about men retracing their fathers' steps over bridges that no longer exist---grapple with memory, imagination, and the nature of art, and explore the notion of writer as witness.
ContributorsHusić, Vedran (Author) / Pritchard, Melissa (Thesis advisor) / Ison, Tara (Committee member) / Turchi, Peter (Committee member) / Arizona State University (Publisher)
Created2013
152239-Thumbnail Image.png
Description
Production from a high pressure gas well at a high production-rate encounters the risk of operating near the choking condition for a compressible flow in porous media. The unbounded gas pressure gradient near the point of choking, which is located near the wellbore, generates an effective tensile stress on the

Production from a high pressure gas well at a high production-rate encounters the risk of operating near the choking condition for a compressible flow in porous media. The unbounded gas pressure gradient near the point of choking, which is located near the wellbore, generates an effective tensile stress on the porous rock frame. This tensile stress almost always exceeds the tensile strength of the rock and it causes a tensile failure of the rock, leading to wellbore instability. In a porous rock, not all pores are choked at the same flow rate, and when just one pore is choked, the flow through the entire porous medium should be considered choked as the gas pressure gradient at the point of choking becomes singular. This thesis investigates the choking condition for compressible gas flow in a single microscopic pore. Quasi-one-dimensional analysis and axisymmetric numerical simulations of compressible gas flow in a pore scale varicose tube with a number of bumps are carried out, and the local Mach number and pressure along the tube are computed for the flow near choking condition. The effects of tube length, inlet-to-outlet pressure ratio, the number of bumps and the amplitude of the bumps on the choking condition are obtained. These critical values provide guidance for avoiding the choking condition in practice.
ContributorsYuan, Jing (Author) / Chen, Kangping (Thesis advisor) / Wang, Liping (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2013
152240-Thumbnail Image.png
Description
A simple passion for reading compels many to enter the university literature classroom. What happens once they arrive may fuel that passion, or possibly destroy it. A romanticized relationship with literature proves to be an obstacle that hinders a deeper and richer engagement with texts. Primary research consisting of personal

A simple passion for reading compels many to enter the university literature classroom. What happens once they arrive may fuel that passion, or possibly destroy it. A romanticized relationship with literature proves to be an obstacle that hinders a deeper and richer engagement with texts. Primary research consisting of personal interviews, observations, and surveys, form the source of data for this dissertation project which was designed to examine how literature teachers engage their students with texts, discussion, and assignments in the university setting. Traditionally text centered and resolute, literature courses will need refashioning if they are to advance beyond erstwhile conventions. The goal of this study is to create space for a dialogue about the need for a pedagogy of literature.
ContributorsSanchez, Shillana (Author) / Goggin, Maureen (Thesis advisor) / Tobin, Beth (Thesis advisor) / Rose, Shirley (Committee member) / Arizona State University (Publisher)
Created2013
152181-Thumbnail Image.png
Description
The objective of this thesis was to compare various approaches for classification of the `good' and `bad' parts via non-destructive resonance testing methods by collecting and analyzing experimental data in the frequency and time domains. A Laser Scanning Vibrometer was employed to measure vibrations samples in order to determine the

The objective of this thesis was to compare various approaches for classification of the `good' and `bad' parts via non-destructive resonance testing methods by collecting and analyzing experimental data in the frequency and time domains. A Laser Scanning Vibrometer was employed to measure vibrations samples in order to determine the spectral characteristics such as natural frequencies and amplitudes. Statistical pattern recognition tools such as Hilbert Huang, Fisher's Discriminant, and Neural Network were used to identify and classify the unknown samples whether they are defective or not. In this work, a Finite Element Analysis software packages (ANSYS 13.0 and NASTRAN NX8.0) was used to obtain estimates of resonance frequencies in `good' and `bad' samples. Furthermore, a system identification approach was used to generate Auto-Regressive-Moving Average with exogenous component, Box-Jenkins, and Output Error models from experimental data that can be used for classification
ContributorsJameel, Osama (Author) / Redkar, Sangram (Thesis advisor) / Arizona State University (Publisher)
Created2013
152242-Thumbnail Image.png
Description
En el siglo XXI nuestra vida se está cruzando constantemente con la tecnología, tanto que algunos declaran que nuestro mundo se ha hecho posthumano, ya que no se puede separar al ser humano de la máquina. Aunque algunos se sientan amenazados por estas tecnologías, otros están abrazando la Red Mundial,

En el siglo XXI nuestra vida se está cruzando constantemente con la tecnología, tanto que algunos declaran que nuestro mundo se ha hecho posthumano, ya que no se puede separar al ser humano de la máquina. Aunque algunos se sientan amenazados por estas tecnologías, otros están abrazando la Red Mundial, aprovechándose de las infinitas oportunidades que ofrece. Uno de estos elementos fundamentales que internet posibilita es la capacidad de comunicarse directamente con otras personas. El blog por ejemplo, o bitácora en español, permite que los usuarios se proyecten a sí mismos o a sus pseudo-identidades, sus pensamientos e ideas a través del texto que escriben en internet. También sus lectores pueden responder a estos autores inmediatamente. Los posts publicados--entradas en una página web--, aunque aparecen cronológicamente, son episodios fragmentados. Pero el blog no se limita a la producción de un texto sino que el autor puede también "jugar" con el cuerpo del texto para añadir hipervínculos y multimedia. Esta forma de escribir está cambiando lo que se considera "válido" como texto, incluso lo que se considera literatura. El objetivo de este trabajo no es estudiar la literatura digital en su totalidad, sino específicamente en algunas obras escritas por mujeres en internet. Si se considera la escritura digital como una forma de arte marginalizada, se podría decir que la escritura realizada por mujeres en internet experimenta una doble-marginalidad debido al hecho de que la literatura de mujeres siempre ha sido marginal al canon. Este estudio tomará un punto de vista transatlántico, incluyendo en el mismo a varias escritoras hispanohablantes de diferentes edades, experiencias y con variados motivos en su trabajo que publican sus obras en internet. Estas autoras incluyen las blogueras Almudena Montero (española) yMaría Amelia López Soliño (española); la periodista ciudadana Yoanis Sánchez (cubana); y la poeta digital/crítica Belén Gache (española-argentina). En esta tesis he explorado y considerado la noción de que el internet sirve como un medio de democratización puesto que, hasta cierto punto, las fronteras de género y nacionalidad desaparecen. Por esta razón, este trabajo va a considerar varias teorías tales como el postmodernismo, las teorías sobre la escritura de mujeres y teorías sobre la democratización de la tecnología para analizar la literatura que se encuentra en la red. Aunque las escritoras analizadas en este proyecto son distintas, y usan la tecnología de maneras diferentes, tienen una misma meta: expresarse libremente y comunicarse directamente con sus lectores al conectarse a internet. Mi hipótesis de trabajo consiste en que estas mujeres escriben de una manera particular--es decir, que no escriben igual a los hombres que escriben en internet--y que la red ofrece una plataforma única a las mujeres: en este espacio ellas son más activas--en oposición a la literatura tradicional-- en cuanto a compartir y publicar su propio trabajo e ideas.
ContributorsByron, Jennifer E. (Author) / Urioste-Azcorra, Carmen (Thesis advisor) / Tompkins, Cynthia (Committee member) / García-Fernández, Carlos Javier (Committee member) / Arizona State University (Publisher)
Created2013
152246-Thumbnail Image.png
Description
Smoke entering a flight deck cabin has been an issue for commercial aircraft for many years. The issue for a flight crew is how to mitigate the smoke so that they can safely fly the aircraft. For this thesis, the feasibility of having a Negative Pressure System that utilizes the

Smoke entering a flight deck cabin has been an issue for commercial aircraft for many years. The issue for a flight crew is how to mitigate the smoke so that they can safely fly the aircraft. For this thesis, the feasibility of having a Negative Pressure System that utilizes the cabin altitude pressure and outside altitude pressure to remove smoke from a flight deck was studied. Existing procedures for flight crews call for a descent down to a safe level for depressurizing the aircraft before taking further action. This process takes crucial time that is critical to the flight crew's ability to keep aware of the situation. This process involves a flight crews coordination and fast thinking to manually take control of the aircraft; which has become increasing more difficult due to the advancements in aircraft automation. Unfortunately this is the only accepted procedure that is used by a flight crew. Other products merely displace the smoke. This displacement is after the time it takes for the flight crew to set up the smoke displacement unit with no guarantee that a flight crew will be able to see or use all of the aircraft's controls. The Negative Pressure System will work automatically and not only use similar components already found on the aircraft, but work in conjunction with the smoke detection system and pressurization system so smoke removal can begin without having to descend down to a lower altitude. In order for this system to work correctly many factors must be taken into consideration. The size of a flight deck varies from aircraft to aircraft, therefore the ability for the system to efficiently remove smoke from an aircraft is taken into consideration. For the system to be feasible on an aircraft the cost and weight must be taken into consideration as the added fuel consumption due to weight of the system may be the limiting factor for installing such a system on commercial aircraft.
ContributorsDavies, Russell (Author) / Rogers, Bradley (Thesis advisor) / Palmgren, Dale (Committee member) / Rajadas, John (Committee member) / Arizona State University (Publisher)
Created2013
152254-Thumbnail Image.png
Description
The friction condition is an important factor in controlling the compressing process in metalforming. The friction calibration maps (FCM) are widely used in estimating friction factors between the workpiece and die. However, in standard FEA, the friction condition is defined by friction coefficient factor (µ), while the FCM is used

The friction condition is an important factor in controlling the compressing process in metalforming. The friction calibration maps (FCM) are widely used in estimating friction factors between the workpiece and die. However, in standard FEA, the friction condition is defined by friction coefficient factor (µ), while the FCM is used to a constant shear friction factors (m) to describe the friction condition. The purpose of this research is to find a method to convert the m factor to u factor, so that FEA can be used to simulate ring tests with µ. The research is carried out with FEA and Design of Experiment (DOE). FEA is used to simulate the ring compression test. A 2D quarter model is adopted as geometry model. A bilinear material model is used in nonlinear FEA. After the model is established, validation tests are conducted via the influence of Poisson's ratio on the ring compression test. It is shown that the established FEA model is valid especially if the Poisson's ratio is close to 0.5 in the setting of FEA. Material folding phenomena is present in this model, and µ factors are applied at all surfaces of the ring respectively. It is also found that the reduction ratio of the ring and the slopes of the FCM can be used to describe the deformation of the ring specimen. With the baseline FEA model, some formulas between the deformation parameters, material mechanical properties and µ factors are generated through the statistical analysis to the simulating results of the ring compression test. A method to substitute the m factor with µ factors for particular material by selecting and applying the µ factor in time sequence is found based on these formulas. By converting the m factor into µ factor, the cold forging can be simulated.
ContributorsKexiang (Author) / Shah, Jami (Thesis advisor) / Davidson, Joseph (Committee member) / Trimble, Steve (Committee member) / Arizona State University (Publisher)
Created2013