Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
Displaying 1 - 10 of 143
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
CYOA is a prototype of an iPhone application that produces a single, generative, musical work. This document details some of the thoughts and practices that informed its design, and specifically addresses the overlap between application structure and musical form. The concept of composed instruments is introduced and briefly discussed, some features of video game design that relate to this project are considered, and some specifics of hardware implementation are addressed.
ContributorsPeterson, Julian (Author) / Hackbarth, Glenn (Thesis advisor) / DeMars, James (Committee member) / Feisst, Sabine (Committee member) / Levy, Benjamin (Committee member) / Tobias, Evan (Committee member) / Arizona State University (Publisher)
Created2013
Description
Johann Sebastian Bach's violin Sonata I in G minor, BWV 1001, is a significant and widely performed work that exists in numerous editions and also as transcriptions or arrangements for various other instruments, including the guitar. A pedagogical guitar performance edition of this sonata, however, has yet to be published. Therefore, the core of my project is a transcription and pedagogical edition of this work for guitar. The transcription is supported by an analysis, performance and pedagogical practice guide, and a recording. The analysis and graphing of phrase structures illuminate Bach's use of compositional devices and the architectural function of the work's harmonic gravities. They are intended to guide performers in their assessment of the surface ornamentation and suggest a reduction toward its fundamental purpose. The end result is a clarification of the piece through the organization of phrase structures and the prioritization of harmonic tensions and resolutions. The compiling process is intended to assist the performer in "seeing the forest from the trees." Based on markings from Bach's original autograph score, the transcription considers fingering ease on the guitar that is critical to render the music to a functional and practical level. The goal is to preserve the composer's indications to the highest degree possible while still adhering to the technical confines that allow for actual execution on the guitar. The performance guide provides suggestions for articulation, phrasing, ornamentation, and other interpretive decisions. Considering the limitations of the guitar, the author's suggestions are grounded in various concepts of historically informed performance, and also relate to today's early-music sensibilities. The pedagogical practice guide demonstrates procedures to break down and assimilate the musical material as applied toward the various elements of guitar technique and practice. The CD recording is intended to demonstrate the transcription and the connection to the concepts discussed. It is hoped that this pedagogical edition will provide a rational that serves to support technical decisions within the transcription and generate meaningful interpretive realizations based on principles of historically informed performance.
ContributorsFelice, Joseph Philip (Author) / Koonce, Frank (Thesis advisor) / Feisst, Sabine (Committee member) / Swartz, Jonathan (Committee member) / Arizona State University (Publisher)
Created2013
Description
This project features three new pieces for clarinet commissioned from three different composers. Two are for unaccompanied clarinet and one is for clarinet, bass clarinet, and laptop. These pieces are Storm's a Comin' by Chris Burton, Light and Shadows by Theresa Martin, and My Own Agenda by Robbie McCarthy. These three solos challenge the performer in various ways including complex rhythm, use of extended techniques such as growling, glissando, and multiphonics, and the incorporation of technology into a live performance. In addition to background information, a performance practice guide has also been included for each of the pieces. This guide provides recommendations and suggestions for future performers wishing to study and perform these works. Also included are transcripts of interviews done with each of the composers as well as full scores for each of the pieces. Accompanying this document are recordings of each of the three pieces, performed by the author.
ContributorsVaughan, Melissa Lynn (Author) / Spring, Robert (Thesis advisor) / Micklich, Albie (Committee member) / Gardner, Joshua (Committee member) / Hill, Gary (Committee member) / Feisst, Sabine (Committee member) / Arizona State University (Publisher)
Created2013
Description
Three Meditations on the Philosophy of Boethius is a musical piece for guitar, piano interior, and computer. Each of the three movements, or meditations, reflects one level of music according to the medieval philosopher Boethius: Musica Mundana, Musica Humana, and Musica Instrumentalis. From spatial aspects, through the human element, to letting sound evolve freely, different movements revolve around different sounds and sound producing techniques.
ContributorsDori, Gil (Contributor) / Hackbarth, Glenn (Thesis advisor) / DeMars, James (Committee member) / Feisst, Sabine (Committee member) / Arizona State University (Publisher)
Created2013
Description
There is a lack of music therapy services for college students who have problems with depression and/or anxiety. Even among universities and colleges that offer music therapy degrees, there are no known programs offering music therapy to the institution's students. Female college students are particularly vulnerable to depression and anxiety symptoms compared to their male counterparts. Many students who experience mental health problems do not receive treatment, because of lack of knowledge, lack of services, or refusal of treatment. Music therapy is proposed as a reliable and valid complement or even an alternative to traditional counseling and pharmacotherapy because of the appeal of music to young women and the potential for a music therapy group to help isolated students form supportive networks. The present study recruited 14 female university students to participate in a randomized controlled trial of short-term group music therapy to address symptoms of depression and anxiety. The students were randomly divided into either the treatment group or the control group. Over 4 weeks, each group completed surveys related to depression and anxiety. Results indicate that the treatment group's depression and anxiety scores gradually decreased over the span of the treatment protocol. The control group showed either maintenance or slight worsening of depression and anxiety scores. Although none of the results were statistically significant, the general trend indicates that group music therapy was beneficial for the students. A qualitative analysis was also conducted for the treatment group. Common themes were financial concerns, relationship problems, loneliness, and time management/academic stress. All participants indicated that they benefited from the sessions. The group progressed in its cohesion and the participants bonded to the extent that they formed a supportive network which lasted beyond the end of the protocol. The results of this study are by no means conclusive, but do indicate that colleges with music therapy degree programs should consider adding music therapy services for their general student bodies.
ContributorsAshton, Barbara (Author) / Crowe, Barbara J. (Thesis advisor) / Rio, Robin (Committee member) / Davis, Mary (Committee member) / Arizona State University (Publisher)
Created2013
Description
Shock loading is a complex phenomenon that can lead to failure mechanisms such as strain localization, void nucleation and growth, and eventually spall fracture. Studying incipient stages of spall damage is of paramount importance to accurately determine initiation sites in the material microstructure where damage will nucleate and grow and to formulate continuum models that account for the variability of the damage process due to microstructural heterogeneity. The length scale of damage with respect to that of the surrounding microstructure has proven to be a key aspect in determining sites of failure initiation. Correlations have been found between the damage sites and the surrounding microstructure to determine the preferred sites of spall damage, since it tends to localize at and around the regions of intrinsic defects such as grain boundaries and triple points. However, considerable amount of work still has to be done in this regard to determine the physics driving the damage at these intrinsic weak sites in the microstructure. The main focus of this research work is to understand the physical mechanisms behind the damage localization at these preferred sites. A crystal plasticity constitutive model is implemented with different damage criteria to study the effects of stress concentration and strain localization at the grain boundaries. A cohesive zone modeling technique is used to include the intrinsic strength of the grain boundaries in the simulations. The constitutive model is verified using single elements tests, calibrated using single crystal impact experiments and validated using bicrystal and multicrystal impact experiments. The results indicate that strain localization is the predominant driving force for damage initiation and evolution. The microstructural effects on theses damage sites are studied to attribute the extent of damage to microstructural features such as grain orientation, misorientation, Taylor factor and the grain boundary planes. The finite element simulations show good correlation with the experimental results and can be used as the preliminary step in developing accurate probabilistic models for damage nucleation.
ContributorsKrishnan, Kapil (Author) / Peralta, Pedro (Thesis advisor) / Mignolet, Marc (Committee member) / Sieradzki, Karl (Committee member) / Jiang, Hanqing (Committee member) / Oswald, Jay (Committee member) / Arizona State University (Publisher)
Created2013
Description
Piano Quintet> is a three movement piece, inspired by music of Eastern Europe. Sunrise in Hungary starts with a legato song in the first violin unfolding over slow moving sustained harmonics in the rest of the strings. This is contrasted with a lively Hungarian dance which starts in the piano and jumps throughout all of the voices. Armenian Lament introduces a mournful melody performed over a subtly shifting pedal tone in the cello. The rest of the voices are slowly introduced until the movement builds into a canonic threnody. Evening in Bulgaria borrows from the vast repertoire of Bulgarian dances, including rhythms from the horo and rachenitsa. Each time that the movement returns to the primary theme, it incorporates aspects of the dance that directly preceded it. The final return is the crux of the piece, with the first violin playing a virtuosic ornaments run on the melody.
ContributorsGiese, Adam (Composer) / Hackbarth, Glenn (Thesis advisor) / DeMars, James (Committee member) / Feisst, Sabine (Committee member) / Arizona State University (Publisher)
Created2014
Description
Sometimes difficult life events challenge our existing resources in such a way that routinized responses are inadequate to handle the challenge. Some individuals will persist in habitual, automatic behavior, regardless of environmental cues that indicate a mismatch between coping strategy and the demands of the stressor. Other individuals will marshal adaptive resources to construct new courses of action and reconceptualize the problem, associated goals and/or values. A mixed methods approach was used to describe and operationalize cognitive shift, a relatively unexplored construct in existing literature. The study was conducted using secondary data from a parent multi-year cross-sectional study of resilience with eight hundred mid-aged adults from the Phoenix metro area. Semi-structured telephone interviews were analyzed using a purposive sample (n=136) chosen by type of life event. Participants' beliefs, assumptions, and experiences were examined to understand how they shaped adaptation to adversity. An adaptive mechanism, "cognitive shift," was theorized as the transition from automatic coping to effortful cognitive processes aimed at novel resolution of issues. Aims included understanding when and how cognitive shift emerges and manifests. Cognitive shift was scored as a binary variable and triangulated through correlational and logistic regression analyses. Interaction effects revealed that positive personality attributes influence cognitive shift most when people suffered early adversity. This finding indicates that a certain complexity, self-awareness and flexibility of mind may lead to a greater capacity to find meaning in adversity. This work bridges an acknowledged gap in literature and provides new insights into resilience.
ContributorsRivers, Crystal T (Author) / Zautra, Alex (Thesis advisor) / Davis, Mary (Committee member) / Kurpius, Sharon (Committee member) / Arizona State University (Publisher)
Created2014
Description
Recent studies of the occurrence of post-flutter limit cycle oscillations (LCO) of the F-16 have provided good support to the long-standing hypothesis that this phenomenon involves a nonlinear structural damping. A potential mechanism for the appearance of nonlinearity in the damping are the nonlinear geometric effects that arise when the deformations become large enough to exceed the linear regime. In this light, the focus of this investigation is first on extending nonlinear reduced order modeling (ROM) methods to include viscoelasticity which is introduced here through a linear Kelvin-Voigt model in the undeformed configuration. Proceeding with a Galerkin approach, the ROM governing equations of motion are obtained and are found to be of a generalized van der Pol-Duffing form with parameters depending on the structure and the chosen basis functions. An identification approach of the nonlinear damping parameters is next proposed which is applicable to structures modeled within commercial finite element software.
The effects of this nonlinear damping mechanism on the post-flutter response is next analyzed on the Goland wing through time-marching of the aeroelastic equations comprising a rational fraction approximation of the linear aerodynamic forces. It is indeed found that the nonlinearity in the damping can stabilize the unstable aerodynamics and lead to finite amplitude limit cycle oscillations even when the stiffness related nonlinear geometric effects are neglected. The incorporation of these latter effects in the model is found to further decrease the amplitude of LCO even though the dominant bending motions do not seem to stiffen as the level of displacements is increased in static analyses.
The effects of this nonlinear damping mechanism on the post-flutter response is next analyzed on the Goland wing through time-marching of the aeroelastic equations comprising a rational fraction approximation of the linear aerodynamic forces. It is indeed found that the nonlinearity in the damping can stabilize the unstable aerodynamics and lead to finite amplitude limit cycle oscillations even when the stiffness related nonlinear geometric effects are neglected. The incorporation of these latter effects in the model is found to further decrease the amplitude of LCO even though the dominant bending motions do not seem to stiffen as the level of displacements is increased in static analyses.
ContributorsSong, Pengchao (Author) / Mignolet, Marc P (Thesis advisor) / Chattopadhyay, Aditi (Committee member) / Oswald, Jay (Committee member) / Arizona State University (Publisher)
Created2015