ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
Displaying 81 - 86 of 86
Description
As an urgency has emerged to prepare students to be future-ready, makerspaces have been developed as a technique for teachers to use in classrooms to build science, technology, engineering and math (STEM) skills. Makerspaces expose students to innovation and are powerful tools in training students to use science and engineering practices as they invent, discover and tinker. While indoor makerspaces have been studied in multiple settings, little research has been performed to understand the relevance of makerspaces in outdoor settings.
The goal of this study was to aid 20 elementary teachers in developing their understanding of the usefulness and benefits of outdoor makerspaces. A constructivist approach was used in order for participants to overcome pre-conceived barriers about taking students outside for learning. In this qualitative study, participants took part in a hands-on professional development session to learn how to integrate nature into instruction, then used outdoor spaces to engage their own students in three or more outdoor sessions. Teachers reflected before, during and after the intervention to see if the likelihood of engaging students in outdoor learning changed.
The findings of the study showed that spending time outside with students led to a multitude of benefits for both students and teachers. Benefits included increased student engagement, expanded learning for students and teachers, and STEM skill development. These findings, suggest that outdoor makerspaces introduce a new platform for training students and teachers about science and engineering practices while providing authentic science connections, high engagement, and benefits to social and emotional balance.
The goal of this study was to aid 20 elementary teachers in developing their understanding of the usefulness and benefits of outdoor makerspaces. A constructivist approach was used in order for participants to overcome pre-conceived barriers about taking students outside for learning. In this qualitative study, participants took part in a hands-on professional development session to learn how to integrate nature into instruction, then used outdoor spaces to engage their own students in three or more outdoor sessions. Teachers reflected before, during and after the intervention to see if the likelihood of engaging students in outdoor learning changed.
The findings of the study showed that spending time outside with students led to a multitude of benefits for both students and teachers. Benefits included increased student engagement, expanded learning for students and teachers, and STEM skill development. These findings, suggest that outdoor makerspaces introduce a new platform for training students and teachers about science and engineering practices while providing authentic science connections, high engagement, and benefits to social and emotional balance.
ContributorsEstes, Patricia Chantel (Author) / Fischman, Gustavo (Thesis advisor) / Keena, Kelly (Committee member) / Wolf, Leigh (Committee member) / Arizona State University (Publisher)
Created2020
Description
The purpose of this study was to understand Black students within the Class of 2023 at Cleveland Heights High School (CHHS) motivation for pursuing a post-secondary education through the lens of Critical Race Theory (CRT), Community Cultural Wealth (CCW) and Counter-storytelling. CHHS is identified as a comprehensive high school where students have access to a rigorous, engaging curriculum that will prepare them for college and career. CHHS is located on the East side of Cleveland and has a predominately Black student population. Despite the district and CHHS efforts to cultivate a college going culture, the college enrollment rate is around 46 percent. This study utilized a qualitative Critical Race Methodology (CRM) as a guiding framework in order to negate the deficit thinking stereotype that U.S society has unjustly placed on Black students in their pursuit of higher education. CRM in education challenges biological and cultural deficit stories through counter-storytelling, oral traditions, historiographies, etc., (Solórzano & Yosso, 2002, p.37). Utilizing this framework allowed Black students to see their life experiences as a source of value and a beneficial asset. By understanding students’ motivations for pursuing a postsecondary education will in turn help build systems of support as they prepare to tackle perceived post-secondary barriers. Study participants are a part of the Gaining Early Awareness and Readiness for Undergraduate Program (GEAR UP). The students that participated in the study met the following criteria: participate in Gear Up, Black male or female, and first or second-generation college student. This study utilized an action research framework. In order to gain a better understanding of how college and career readiness workshops impacts students understanding and motivations to pursue a postsecondary education; students participated in a five-week long college and career readiness summer program. Students created personal narratives through the lens of counter-narrative storytelling. Counter-narratives are important means to document and share how race influences the educational experiences of people of color (Miller et al., 2020, p.273). The findings were analyzed using verbatim participant responses and four major themes emerged. The implications of this findings and recommendations for future research are provided in the final chapter.
ContributorsDaniel, Carmen C (Author) / Fischman, Gustavo (Thesis advisor) / Graves-Wolf, Leigh (Committee member) / Tefera, Adai (Committee member) / Arizona State University (Publisher)
Created2021
Description
Layer-wise extrusion of soft-solid like cement pastes and mortars is commonly used in 3D printing of concrete. Rheological and mechanical characterization of the printable binder for on-demand flow and subsequent structuration is a critical challenge. This research is an effort to understand the mechanics of cementitious binders as soft solids in the fresh state, towards establishing material-process relationships to enhance print quality. This study introduces 3D printable binders developed based on rotational and capillary rheology test parameters, and establish the direct influence of packing coefficients, geometric ratio, slip velocities, and critical print velocities on the extrudate quality. The ratio of packing fraction to the square of average particle diameter (0.01-0.02), and equivalent microstructural index (5-20) were suitable for printing, and were directly related to the cohesion and extrusional yield stress of the material. In fact, steady state pressure for printing (30-40 kPa) is proportional to the extrusional yield stress, and increases with the geometric ratio (0-60) and print velocity (5-50 mm/s). Higher print velocities results in higher wall shear stresses and was exponentially related to the slip layer thickness (estimated between 1-5μ), while the addition of superplasticizers improve the slip layer thickness and the extrudate flow. However, the steady state pressure and printer capacity limits the maximum print velocity while the deadzone length limits the minimum velocity allowable (critical velocity regime) for printing. The evolution of buildability with time for the fresh state mortars was characterized with digital image correlation using compressive strain and strain rate in printed layers. The fresh state characteristics (interlayer and interfilamentous) and process parameters (layer height and fiber dimensions) influence the hardened mechanical properties. A lower layer height generally improves the mechanical properties and slight addition of fiber (up to 0.3% by volume) results in a 15-30% increase in the mechanical properties. 3D scanning and point-cloud analysis was also used to assess the geometric tolerance of a print based on mean error distances, print accuracy index, and layer-wise percent overlap. The research output will contribute to a synergistic material-process design and development of test methods for printability in the context of 3D printing of concrete.
ContributorsAmbadi Omanakuttan Nair, Sooraj Kumar (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam (Committee member) / Mobasher, Barzin (Committee member) / Hoover, Christian (Committee member) / Chawla, Nikhilesh (Committee member) / Arizona State University (Publisher)
Created2021
Description
Special thermal interface materials are required for connecting devices that operate at high temperatures up to 300°C. Because devices used in power electronics, such as GaN, SiC, and other wide bandgap semiconductors, can reach very high temperatures (beyond 250°C), a high melting point, and high thermal & electrical conductivity are required for the thermal interface material. Traditional solder materials for packaging cannot be used for these applications as they do not meet these requirements. Sintered nano-silver is a good candidate on account of its high thermal and electrical conductivity and very high melting point. The high temperature operating conditions of these devices lead to very high thermomechanical stresses that can adversely affect performance and also lead to failure. A number of these devices are mission critical and, therefore, there is a need for very high reliability. Thus, computational and nondestructive techniques and design methodology are needed to determine, characterize, and design the packages. Actual thermal cycling tests can be very expensive and time consuming. It is difficult to build test vehicles in the lab that are very close to the production level quality and therefore making comparisons or making predictions becomes a very difficult exercise. Virtual testing using a Finite Element Analysis (FEA) technique can serve as a good alternative. In this project, finite element analysis is carried out to help achieve this objective. A baseline linear FEA is performed to determine the nature and magnitude of stresses and strains that occur during the sintering step. A nonlinear coupled thermal and mechanical analysis is conducted for the sintering step to study the behavior more accurately and in greater detail. Damage and fatigue analysis are carried out for multiple thermal cycling conditions. The results are compared with the actual results from a prior study. A process flow chart outlining the FEA modeling process is developed as a template for the future work. A Coffin-Manson type relationship is developed to help determine the accelerated aging conditions and predict life for different service conditions.
ContributorsAmla, Tarun (Author) / Chawla, Nikhilesh (Thesis advisor) / Jiao, Yang (Committee member) / Liu, Yongming (Committee member) / Zhuang, Houlong (Committee member) / Jiang, Hanqing (Committee member) / Arizona State University (Publisher)
Created2020
Description
Over 150 years since the abolition of slavery, African Americans still lack equal access to education and other quality of life markers. However, a slow increase in African American students pursuing and obtaining higher education demonstrates the progress of African American academic success. Although still not at an equitable level, this progress, and the voices of success are often muted by the majoritarian narrative of African American student failure. This research focuses on African American student success and examines the specific socio-cultural characteristics and processes that shape the ways in which African American students develop their own counter-narratives to persist and gain access to higher education. This study utilizes narrative inquiry in the form of interviews, artifacts collection and student-drawn identity maps to understand the factors that influence the development of counter-narratives. The primary research questions included: What narratives did African American students tell themselves to help them persist in school, attain a high school diploma and pursue higher education? How did they develop their narratives? How did their narratives influence their educational experiences? Five African American students who attended an elite public university in the southwest United States participated in four to five interviews ranging from six to ten hours in total. Through the analysis of their stories, the importance of culture and context were clear. Specifically their social support systems including their parents, siblings, teachers and mentors, significantly influenced their identity development and human agency. The findings also point to a critical path forward: if society commits to supporting African American student success, then shine a light on stories of persistence and potential rather than shortcomings and failures.
ContributorsFreeman, Stacey Vicario (Author) / Kozleski, Elizabeth B. (Thesis advisor) / Fischman, Gustavo (Thesis advisor) / Artiles, Alfredo (Committee member) / Arizona State University (Publisher)
Created2016
Description
Over the past several years, the density of integrated circuits has been increasing at a very fast rate, following Moore’s law. The advent of three dimensional (3D) packaging technologies enable the increase in density of integrated circuits without necessarily shrinking the dimensions of the device. Under such constraints, the solder volume necessary to join the various layers of the package is also extremely small. At smaller length scales, the local cooling rates are higher, so the microstructures are much finer than that obtained in larger joints (BGA, C4). The fraction of intermetallic compounds (IMCs) present in solder joints in these volumes will be larger. The Cu6Sn5 precipitate size and spacing, and Sn grain structure and crystallography will be different at very small volumes. These factors will most certainly affect the performance of the solder. Examining the mechanical behavior and reliability of Pb-free solders is difficult, primarily because a methodology to characterize the microstructure and the mechanics of deformation at these extremely small length scales has yet to be developed.
In this study, Sn grain orientation and Cu6Sn5 IMC fraction, size, and morphology are characterized in 3D, in pure Sn based solder joints. The obtained results show differences in morphology of Sn grains and IMC precipitates as a function of location within the solder joint indicating influence of local cooling rate differences. Ex situ and in situ electromigration tests done on 250 um and 500 um pure Sn solder joints elucidate the evolution of microstructure, specifically Sn grain growth, IMC segregation and surface degradation. This research implements 3D quantification of microstructural features over micro and nano-scales, thereby enabling a multi-scale / multi-characterization approach.
In this study, Sn grain orientation and Cu6Sn5 IMC fraction, size, and morphology are characterized in 3D, in pure Sn based solder joints. The obtained results show differences in morphology of Sn grains and IMC precipitates as a function of location within the solder joint indicating influence of local cooling rate differences. Ex situ and in situ electromigration tests done on 250 um and 500 um pure Sn solder joints elucidate the evolution of microstructure, specifically Sn grain growth, IMC segregation and surface degradation. This research implements 3D quantification of microstructural features over micro and nano-scales, thereby enabling a multi-scale / multi-characterization approach.
ContributorsKirubanandham, Antony (Author) / Chawla, Nikhilesh (Thesis advisor) / Jiao, Yang (Committee member) / Lu, Minhua (Committee member) / Rajagopalan, Jagannathan (Committee member) / Arizona State University (Publisher)
Created2016