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Description
The stability of nanocrystalline microstructural features allows structural materials to be synthesized and tested in ways that have heretofore been pursued only on a limited basis, especially under dynamic loading combined with temperature effects. Thus, a recently developed, stable nanocrystalline alloy is analyzed here for quasi-static (<100 s-1) and dynamic loading (103 to 104 s-1) under uniaxial compression and tension at multiple temperatures ranging from 298-1073 K. After mechanical tests, microstructures are analyzed and possible deformation mechanisms are proposed. Following this, strain and strain rate history effects on mechanical behavior are analyzed using a combination of quasi-static and dynamic strain rate Bauschinger testing. The stable nanocrystalline material is found to exhibit limited flow stress increase with increasing strain rate as compared to that of both pure, coarse grained and nanocrystalline Cu. Further, the material microstructural features, which includes Ta nano-dispersions, is seen to pin dislocation at quasi-static strain rates, but the deformation becomes dominated by twin nucleation at high strain rates. These twins are pinned from further growth past nucleation by the Ta nano-dispersions. Testing of thermal and load history effects on the mechanical behavior reveals that when thermal energy is increased beyond 200 °C, an upturn in flow stress is present at strain rates below 104 s-1. However, in this study, this simple assumption, established 50-years ago, is shown to break-down when the average grain size and microstructural length-scale is decreased and stabilized below 100nm. This divergent strain-rate behavior is attributed to a unique microstructure that alters slip-processes and their interactions with phonons; thus enabling materials response with a constant flow-stress even at extreme conditions. Hence, the present study provides a pathway for designing and synthesizing a new-level of tough and high-energy absorbing materials.
ContributorsTurnage, Scott Andrew (Author) / Solanki, Kiran N (Thesis advisor) / Rajagopalan, Jagannathan (Committee member) / Peralta, Pedro (Committee member) / Darling, Kristopher A (Committee member) / Mignolet, Marc (Committee member) / Arizona State University (Publisher)
Created2017
Description
The exceptional mechanical properties of polymers with heterogeneous structure, such as the high toughness of polyethylene and the excellent blast-protection capability of polyurea, are strongly related to their morphology and nanoscale structure. Different polymer microstructures, such as semicrystalline morphology and segregated nanophases, lead to coordinated molecular motions during deformation in order to preserve compatibility between the different material phases. To study molecular relaxation in polyethylene, a coarse-grained model of polyethylene was calibrated to match the local structural variable distributions sampled from supercooled atomistic melts. The coarse-grained model accurately reproduces structural properties, e.g., the local structure of both the amorphous and crystalline phases, and thermal properties, e.g., glass transition and melt temperatures, and dynamic properties: including the vastly different relaxation time scales of the amorphous and crystalline phases. A hybrid Monte Carlo routine was developed to generate realistic semicrystalline configurations of polyethylene. The generated systems accurately predict the activation energy of the alpha relaxation process within the crystalline phase. Furthermore, the models show that connectivity to long chain segments in the amorphous phase increases the energy barrier for chain slip within crystalline phase. This prediction can guide the development of tougher semicrystalline polymers by providing a fundamental understanding of how nanoscale morphology contributes to chain mobility. In a different study, the macroscopic shock response of polyurea, a phase segregated copolymer, was analyzed using density functional theory (DFT) molecular dynamics (MD) simulations and classical MD simulations. The two models predict the shock response consistently up to shock pressures of 15 GPa, beyond which the DFT-based simulations predict a softer response. From the DFT simulations, an analysis of bond scission was performed as a first step in developing a more fundamental understanding of how shock induced material transformations effect the shock response and pressure dependent strength of polyurea subjected to extreme shocks.
ContributorsLi, Yiyang (Author) / Oswald, Jay (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Solanki, Kiran (Committee member) / Chamberlin, Ralph (Committee member) / Rajagopalan, Jagannathan (Committee member) / Arizona State University (Publisher)
Created2017
Description
Guitar Hero III and similar games potentially offer a vehicle for improvement of musical rhythmic accuracy with training delivered in both visual and auditory formats and by use of its novel guitar-shaped interface; however, some theories regarding multimedia learning suggest sound is a possible source of extraneous cognitive load while playing so players may score higher with sound turned off. Also, existing studies have shown that differences in the physical format of interfaces affect learning outcomes. This study sought to determine whether (a) the game’s audio content affects rhythmic accuracy, and (b) the type of game controller used affects learning of rhythmic accuracy. One hundred participants were randomly assigned in approximately equal numbers (ns = 25) to the four cells of a 2x2 between-subjects design. The first variable was the audio content of the game with two levels: on or off. The second variable was the type of game controller: the standard guitar-style controller or tablet interface. Participants across all conditions completed a pre- and post-test with a system that required them to tap along with repeated rhythmic patterns on an electronic drum pad. Statistical evidence showed better outcomes with a tablet controller with respect to input time error, reduction of extra notes played, and reduction of missed notes; however, the guitar-style controller produced superior outcomes in terms of avoiding missed notes and was associated with higher satisfaction by participants. When audio was present better outcomes were achieved at multiple factor-levels of reduction of missed responses, but superior outcomes in input time error were seen without audio. There was no evidence to suggest an interaction between controller type and the presence or absence of audio.
ContributorsThomas, James William (Author) / Zuiker, Steven J (Thesis advisor) / Atkinson, Robert (Thesis advisor) / Savenye, Wilhelmina C (Committee member) / Arizona State University (Publisher)
Created2017
Description
Mexican American adolescents report high rates of internalizing symptomatology and alcohol use. However, very little research has explored to what extent internalizing distress may contribute to alcohol use among this population. The current study utilized longitudinal data from a community sample of Mexican American adolescents (n=626, 51% female) to test a series of hypotheses about the role of internalizing distress on alcohol use and misuse. Specifically, this study used a bifactor modeling approach to investigate (1) whether different forms of internalizing distress are composed of common and unique components; (2) whether and to what extent such components confer risk for alcohol use; and (3) whether youth cultural orientation plays a role in these associations. Confirmatory factor analyses revealed that a bifactor model with a general factor and three specific factors (depressed mood, general worry, social anxiety) provided good fit to the data. The general distress factor was significantly associated with past month alcohol use but not binge drinking. However, these effects were conditional based on level of acculturation. Differential relations were found between the specific factors of internalizing distress and alcohol use. Depressed mood predicted past month alcohol use among girls; social anxiety negatively predicted past three month binge drinking among boys. Overall, results highlight the multidimensional nature of internalizing distress and suggest that both common and unique components of internalizing distress may be relevant to the etiology of alcohol use among Mexican-American adolescents. Findings underscore the importance of considering cultural orientation as a moderating factor when investigating substance use among Hispanic youth. Implications for future research examining the etiological relevance of the internalizing pathway to alcohol use among Hispanic adolescents are discussed.
ContributorsNichter, Brandon (Author) / Gonzales, Nancy (Thesis advisor) / Chassin, Laurie (Committee member) / Barrera, Manuel (Committee member) / Tein, Jenn (Committee member) / Arizona State University (Publisher)
Created2018
Description
Historically, music and the experiences of deaf or hard-of-hearing (DHH) individuals have been intertwined in one manner or another. However, music has never ignited as much hope for the “improvement” of the Deaf experience as during the American oralist movement (ca. 1880-1960) which prioritized lip-reading and speaking over the use of sign language. While it is acknowledged that the oralist movement failed to provide the best possible education to many American DHH students and devastated many within the Deaf community, music scholars have continued to cite publications by oralist educators as rationales for the continued development of music programs for DHH students.
This document is an attempt to reframe the role of music during the American oralist movement with a historical account of ways music was recruited as a tool for teaching vocal articulation at schools for the deaf from 1900 to 1960. During this time period, music was recruited simply as a utility to overcome disability and as an aid for assimilating into the hearing world rather than as the rich experiential phenomenon it could have been for the DHH community. My goal is to add this important caveat to the received history of early institutional music education for DHH students. Primary sources include articles published between 1900 and 1956 in The Volta Review, a journal founded by the oralist leader Alexander Graham Bell (1847-1922).
This document is an attempt to reframe the role of music during the American oralist movement with a historical account of ways music was recruited as a tool for teaching vocal articulation at schools for the deaf from 1900 to 1960. During this time period, music was recruited simply as a utility to overcome disability and as an aid for assimilating into the hearing world rather than as the rich experiential phenomenon it could have been for the DHH community. My goal is to add this important caveat to the received history of early institutional music education for DHH students. Primary sources include articles published between 1900 and 1956 in The Volta Review, a journal founded by the oralist leader Alexander Graham Bell (1847-1922).
ContributorsLloyd, Abby Lynn (Author) / Norton, Kay (Thesis advisor) / Gardner, Joshua (Committee member) / Wells, Christopher (Committee member) / Arizona State University (Publisher)
Created2017
Corrosion and corrosion-fatigue behavior of 7075 aluminum alloys studied by in situ X-ray tomography
Description
7XXX Aluminum alloys have high strength to weight ratio and low cost. They are used in many critical structural applications including automotive and aerospace components. These applications frequently subject the alloys to static and cyclic loading in service. Additionally, the alloys are often subjected to aggressive corrosive environments such as saltwater spray. These chemical and mechanical exposures have been known to cause premature failure in critical applications. Hence, the microstructural behavior of the alloys under combined chemical attack and mechanical loading must be characterized further. Most studies to date have analyzed the microstructure of the 7XXX alloys using two dimensional (2D) techniques. While 2D studies yield valuable insights about the properties of the alloys, they do not provide sufficiently accurate results because the microstructure is three dimensional and hence its response to external stimuli is also three dimensional (3D). Relevant features of the alloys include the grains, subgrains, intermetallic inclusion particles, and intermetallic precipitate particles. The effects of microstructural features on corrosion pitting and corrosion fatigue of aluminum alloys has primarily been studied using 2D techniques such as scanning electron microscopy (SEM) surface analysis along with post-mortem SEM fracture surface analysis to estimate the corrosion pit size and fatigue crack initiation site. These studies often limited the corrosion-fatigue testing to samples in air or specialized solutions, because samples tested in NaCl solution typically have fracture surfaces covered in corrosion product. Recent technological advancements allow observation of the microstructure, corrosion and crack behavior of aluminum alloys in solution in three dimensions over time (4D). In situ synchrotron X-Ray microtomography was used to analyze the corrosion and cracking behavior of the alloy in four dimensions to elucidate crack initiation at corrosion pits for samples of multiple aging conditions and impurity concentrations. Additionally, chemical reactions between the 3.5 wt% NaCl solution and the crack surfaces were quantified by observing the evolution of hydrogen bubbles from the crack. The effects of the impurity particles and age-hardening particles on the corrosion and fatigue properties were examined in 4D.
ContributorsStannard, Tyler (Author) / Chawla, Nikhilesh (Thesis advisor) / Solanki, Kiran N (Committee member) / Goswami, Ramasis (Committee member) / Liu, Yongming (Committee member) / Arizona State University (Publisher)
Created2017
Description
This research paper aims to understand Frank Martin’s Huit préludes pour le piano (1948) as a summary of his compositional styles, by demonstrating common elements between the preludes and Martin’s compositions of other genres.
Swiss musician Frank Martin (1890-1974) composed in many genres, from theatrical and symphonic works to vocal, chamber, and solo works. Huit préludes pour le piano, his best-known piece for solo piano, merits more recognition in the modern repertoire than it currently receives, as it encompasses a wide range of pianistic techniques, colors, and atmospheres to challenge the mature pianist. This set of preludes represents Martin’s unique compositional sound and style, in which Martin retains a sense of tonal functions despite the intense chromaticism in his music. Featured elements in the Huit préludes include the use of the B-A-C-H motive and its alterations, chromatic yet triadic writing, gliding tonality, baroque elements, dodecaphony, stratification, extreme range and registral shifts, octave doublings and displacements, percussive rhythmic drive, large-scale crescendi, and hidden cyclicism. Martin also uses the 12-tone row as a chromatic tool, but rejects atonality and applies the concept without strict enforcement. Influences of music from past eras are evident in the Huit préludes through various compositional techniques and practices such as contrapuntal lines, chant-like declamatory melodies, imitation, toccata, and pedal-points. This research project explores these various techniques within and between the preludes and his works of other genres, and thus identifies the Huit préludes as a consolidation of Martin’s mature sound and style.
Swiss musician Frank Martin (1890-1974) composed in many genres, from theatrical and symphonic works to vocal, chamber, and solo works. Huit préludes pour le piano, his best-known piece for solo piano, merits more recognition in the modern repertoire than it currently receives, as it encompasses a wide range of pianistic techniques, colors, and atmospheres to challenge the mature pianist. This set of preludes represents Martin’s unique compositional sound and style, in which Martin retains a sense of tonal functions despite the intense chromaticism in his music. Featured elements in the Huit préludes include the use of the B-A-C-H motive and its alterations, chromatic yet triadic writing, gliding tonality, baroque elements, dodecaphony, stratification, extreme range and registral shifts, octave doublings and displacements, percussive rhythmic drive, large-scale crescendi, and hidden cyclicism. Martin also uses the 12-tone row as a chromatic tool, but rejects atonality and applies the concept without strict enforcement. Influences of music from past eras are evident in the Huit préludes through various compositional techniques and practices such as contrapuntal lines, chant-like declamatory melodies, imitation, toccata, and pedal-points. This research project explores these various techniques within and between the preludes and his works of other genres, and thus identifies the Huit préludes as a consolidation of Martin’s mature sound and style.
ContributorsTchoi, Lim Angela (Author) / Hamilton, Robert D (Thesis advisor) / Thompson, Janice C (Thesis advisor) / Carpenter, Ellon D (Committee member) / Ryan, Russell R (Committee member) / Arizona State University (Publisher)
Created2017
Description
The interaction between humans and robots has become an important area of research as the diversity of robotic applications has grown. The cooperation of a human and robot to achieve a goal is an important area within the physical human-robot interaction (pHRI) field. The expansion of this field is toward moving robotics into applications in unstructured environments. When humans cooperate with each other, often there are leader and follower roles. These roles may change during the task. This creates a need for the robotic system to be able to exchange roles with the human during a cooperative task. The unstructured nature of the new applications in the field creates a need for robotic systems to be able to interact in six degrees of freedom (DOF). Moreover, in these unstructured environments, the robotic system will have incomplete information. This means that it will sometimes perform an incorrect action and control methods need to be able to correct for this. However, the most compelling applications for robotics are where they have capabilities that the human does not, which also creates the need for robotic systems to be able to correct human action when it detects an error. Activity in the brain precedes human action. Utilizing this activity in the brain can classify the type of interaction desired by the human. For this dissertation, the cooperation between humans and robots is improved in two main areas. First, the ability for electroencephalogram (EEG) to determine the desired cooperation role with a human is demonstrated with a correct classification rate of 65%. Second, a robotic controller is developed to allow the human and robot to cooperate in six DOF with asymmetric role exchange. This system allowed human-robot cooperation to perform a cooperative task at 100% correct rate. High, medium, and low levels of robotic automation are shown to affect performance, with the human making the greatest numbers of errors when the robotic system has a medium level of automation.
ContributorsWhitsell, Bryan Douglas (Author) / Artemiadis, Panagiotis (Thesis advisor) / Santello, Marco (Committee member) / Berman, Spring (Committee member) / Lee, Hyunglae (Committee member) / Polygerinos, Panagiotis (Committee member) / Arizona State University (Publisher)
Created2017
Description
To be a versatile violinist, one needs interdependence of aural, visual and kinesthetic skills. This thesis introduces aural, visual and kinesthetic learning modalities, and explores the way each is used in the Suzuki, Paul Rolland, Orff, Kodály, and Dalcroze methods, as well as in Edwin Gordon’s Musical Learning Theory. Other methods and pedagogical approaches were consulted and influential in developing the curriculum, such as the teaching of Mimi Zweig, but were not included in this paper either because of an overlap with other methods or insufficient comparable material. This paper additionally presents a new curriculum for teaching beginning violin that incorporates aural, visual, and kinesthetic learning in a systematic and comprehensive manner. It also details a sequenced progression to learn new repertoire and develop proficiency with rhythm, solfège, reading and writing musical notation, and left- and right-hand technique.
ContributorsTang, Tee Tong (Author) / Swartz, Jonathan (Thesis advisor) / Schmidt, Margaret (Committee member) / Feisst, Sabine (Committee member) / Arizona State University (Publisher)
Created2017
Description
Aluminum alloys are ubiquitously used in almost all structural applications due to their high strength-to-weight ratio. Their superior mechanical performance can be attributed to complex dispersions of nanoscale intermetallic particles that precipitate out from the alloy’s solid solution and offer resistance to deformation. Although they have been extensively investigated in the last century, the traditional approaches employed in the past haven’t rendered an authoritative microstructural understanding in such materials. The effect of the precipitates’ inherent complex morphology and their three-dimensional (3D) spatial distribution on evolution and deformation behavior have often been precluded. In this study, for the first time, synchrotron-based hard X-ray nano-tomography has been implemented in Al-Cu alloys to measure growth kinetics of different nanoscale phases in 3D and reveal mechanistic insights behind some of the observed novel phase transformation reactions occurring at high temperatures. The experimental results were reconciled with coarsening models from the LSW theory to an unprecedented extent, thereby establishing a new paradigm for thermodynamic analysis of precipitate assemblies. By using a unique correlative approach, a non-destructive means of estimating precipitation-strengthening in such alloys has been introduced. Limitations of using existing mechanical strengthening models in such alloys have been discussed and a means to quantify individual contributions from different strengthening mechanisms has been established.
The current rapid pace of technological progress necessitates the demand for more resilient and high-performance alloys. To achieve this, a thorough understanding of the relationships between material properties and its structure is indispensable. To establish this correlation and achieve desired properties from structural alloys, microstructural response to mechanical stimuli needs to be understood in three-dimensions (3D). To that effect, in situ tests were conducted at the synchrotron (Advanced Photon Source) using Transmission X-Ray Microscopy as well as in a scanning electron microscope (SEM) to study real-time damage evolution in such alloys. Findings of precipitate size-dependent transition in deformation behavior from these tests have inspired a novel resilient aluminum alloy design.
The current rapid pace of technological progress necessitates the demand for more resilient and high-performance alloys. To achieve this, a thorough understanding of the relationships between material properties and its structure is indispensable. To establish this correlation and achieve desired properties from structural alloys, microstructural response to mechanical stimuli needs to be understood in three-dimensions (3D). To that effect, in situ tests were conducted at the synchrotron (Advanced Photon Source) using Transmission X-Ray Microscopy as well as in a scanning electron microscope (SEM) to study real-time damage evolution in such alloys. Findings of precipitate size-dependent transition in deformation behavior from these tests have inspired a novel resilient aluminum alloy design.
ContributorsKaira, Chandrashekara Shashank (Author) / Chawla, Nikhilesh (Thesis advisor) / Solanki, Kiran (Committee member) / Jiao, Yang (Committee member) / De Andrade, Vincent (Committee member) / Arizona State University (Publisher)
Created2017