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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 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
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 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
Description
In the last years of the twentieth century, while the narrative of women in other Latin American countries has received critical attention, Bolivian women's narrative has been widely ignored. The fact that the voice of Bolivian women in Latin American feminist discourse is rarely discussed in Latin American criticism is enough to justify the present study. This work focuses on three prominent Bolivian writers: Gaby Vallejos, Giovanna Rivero Santa Cruz, and Erika Bruzonic. The short stories of these three authors are characterized by accentuating certain telluric features revealed in the background of their feminine/feminist narratives. At the same time, based on the American and European feminist literary critique, this work analyzes the feminine/feminist themes mounted in the narrative of these authors. Gaby Vallejos, with a cinematic style, chronicles the life and customs of the "valluno" context, building a mosaic of different voices in dialogue. Her topics revolve around binaries: life-death, and pain and pleasure, voicing condemnation for a patriarchal society. Ericka Bruzonic deals with women and identity, memory and the breaking of lineage as an imposing structure. Her themes are built around the cosmopolitism of "paceña" urban life, and her voice transgresses the binomials established by a patriarchal society. Finally Giovanna Rivero Santa Cruz takes the life and customs of the Santa Cruz and the Guarani culture and her plots weave these elements reaching for myths and taboos, involving the reader into her stories. In this manner, her narrative makes an incursion into the conscious and unconscious realm of the readers questioning their wealth of moral and social values, their notions of heterosexuality, and sexual taboos. The three writers, with different narrative styles yet dialogical, narrate various experiences of women from different regions, social classes, ages, education, and sexual orientations. Our authors give high value to the word and the body embedded in the culture, thereby affirming their woman's voice as Bolivians and their literary presence in the context of Latin American literature.
ContributorsLopez, Norma (Author) / Urioste-Ascorra, Carmen (Thesis advisor) / Tompkins, Cynthia (Committee member) / Rosales, Jesus (Committee member) / Arizona State University (Publisher)
Created2013
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 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
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 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
Community-based development: scaling up the correct use of misoprostol at home births in Afghanistan
Description
Globally, more than 350 000 women die annually from complications during pregnancy and childbirth (UNFPA, 2011). Nearly 99% of these, according to World Health Organization (WHO) trends (2010) occur in the developing world outside of a hospital setting with limited resources including emergency care (WHO, 2012; UNFPA, 2011). The most prevalent cause of death is postpartum hemorrhage (PPH), accounting for 25% of deaths according to WHO statistics (2012). Conditions in Afghanistan are reflective of the scope and magnitude of the problem. In Afghanistan, maternal mortality is thought to be among the highest in the world. The Afghan Mortality Survey (AMS) data implies that one Afghan woman dies about every 2 hours from pregnancy-related causes (AMS, 2010). Lack of empowerment, education and access to health care resources increase a woman's risk of dying during pregnancy (AMS, 2010). This project aims to investigate the prospects of scaling-up the correct use of misoprostol, a prostaglandin E1 analogue, to treat PPH in developing countries where skilled assistance and resources are scant. As there has been little published on the lessons learned from programs already in place, this study is experience-driven, based on the knowledge of industry experts. This study employs a concurrent triangulation approach to synthesize quantitative data obtained from previous studies with qualitative information gathered through the testimonies of key personnel who participated in pilot programs involving misoprostol. There are many obstacles to scaling-up training initiatives in Afghanistan and other low-resource areas. The analysis concludes that the most crucial factors for scaling-up community-based programs include: more studies analyzing lessons learns from community driven approaches; stronger partnerships with community health care workers; overcoming barriers like association with abortion, misuse and product issues; and a heightened global and community awareness of the severity of PPH without treatment. These results have implications for those who actively work in Afghanistan to promote maternal health and other countries that may use Afghanistan's work as a blueprint for reducing maternal mortality through community-based approaches. Keywords: Afghanistan, community-based interventions, community-driven, maternal mortality, MDG5, misoprostol, postpartum hemorrhage, reproduction, scale-up
ContributorsCristy, Candice (Author) / Grossman, Gary (Thesis advisor) / Parmentier, Mary-Jane (Committee member) / Byrd, Denise (Committee member) / Arizona State University (Publisher)
Created2013
Description
This dissertation integrates humanities with social science methodologies within a critical framework, seeking to explore the relationship between the neoliberal restructuring and the intersection of gender, class and heteronormativity in contemporary China. In this project, neoliberalism is conceptualized as an art of governance centering on the intersection of race, gender, class and sexuality to create market subjects and sustain market competition. Focusing on China's recent socio-economic and cultural upheavals, this dissertation tries to address these questions: 1. How have class inequalities, binaristic gender and heteronormative discourses been employed intersectionally by the Chinese state to facilitate China's social transformation? 2. How has this process been justified and consolidated through the intersection of gender, class, sexuality and race? 3. How do the marginalized groups respond to these material and cultural practices? Building on the discursive analysis of China's televised 60th anniversary ceremony and If You Are the One, a popular Chinese reality show, as well as the data from the interview, focus group and participant observation of more than 100 informants, it is found that the intersection of gender, class and heteronormativity is central to China's neoliberal transition. A group of flexible and cheap laborers have been disarticulated and rearticulated from the population as the voluntary servitude to China's marketization and re-integration with the global economy. New controlling images, such as the bourgeois nucleus family, are created to legitimize this process. However, these disparate material and discursive practices have entailed contradictions and conflicts within the intersectional biopolitical system, and created contingent spaces of ungovernability for the marginalized groups. Building on these discursive analyses and empirical data, I reconceptualize intersectionality as a multi-dimensional-and-directional network to regulate and manage power for social organization and regulation, which grounds the biopolitical basics for the neoliberal economy. Thus I argue that we need to engage with the dynamics between the intersectional biopolitical structure and people's emerging experiences to construct a grounded utopia alternative to the neoliberal dominance for substantive social changes.
ContributorsZhang, Charlie Yi (Author) / Quan, H. L. T. (Thesis advisor) / Fonow, Mary Margaret (Thesis advisor) / Martinez, Jacqueline M. (Committee member) / Lee, Charles T. (Committee member) / Arizona State University (Publisher)
Created2013
Description
The purpose of my dissertation project is to understand how Same-Gender Loving (SGL) Black Christian men negotiate their sexuality and spirituality in spaces that are not always accepting of SGL people, by examining on how Black SGL men perform their sexual identities within hegemonic institutions that often deny their existence or outwardly seek to exclude them from their communities. I have identified three scripts that Black SGL men often follow within Black religious settings. The first script that SGL people often follow in the church is that of deliverance-- confessing their same-gender desires and maintaining that they have been delivered from those desires The second is "don't ask don't tell" performed by men who many believe and suspect of being SGL; so long as they do not publicly affirm these beliefs they are able to hold a variety of positions in their religious communities.. The last script involves accepting one's same-gender desires and also affirming one's Christian beliefs, proclaiming that the two are not at odds with one another. I examine how these scripts and/or others are performed by and on the bodies of Black SGL males in two distinct sites. The first is the career and music of former gospel star Anthony Charles Williams II (Tonex / B. Slade), who has utilized the three scripts at various times in his career. The next site is that of theatre, where I explore how these scripts have been employed in dramatic texts. By reading Christian Black SGL performance through its theological parameters, I aim to discern the avenues in which Black people in the United States are able to perform same-gender sexual identities in spaces that are constructed as "homophobic," and in so doing combat the narrative of hyper-homophobia in Black communities.
ContributorsChester, Tabitha Jamie Mary (Author) / Anderson, Lisa (Thesis advisor) / Leong, Karen J (Committee member) / Honegger, Gitta (Committee member) / Arizona State University (Publisher)
Created2013
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 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
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 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