Collection Description

Collection of student theses and dissertations from as early as 1939, but mainly from 2010 to present.

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.Net visualization suite for Kloosterman cardioid research
Includes bibliographical references (p. 27), In August 2007 a parallel/distributed computer program designed and coded by a team of SDSU computer science graduate students, after running continuously for more than seven months on a 45-node commodity PC cluster, emitted a single 5-digit integer: a prime number counterexample disproving the Evans Conjecture on Kloosterman Sums. In the course of their research, the students discovered another fascinating fact: when the points on the unit circle corresponding to the set of all normalized Kloosterman sums for a given prime p were computed in a particular order and connected by line segments, the resulting graph contained a pronounced embedded epicycloidal locus. In particular, it appeared that for primes p for which the finite field GF(p) has g=2 as a generator, the locus is a cardioid whose axis of symmetry differs for different p . This thesis project is one of a group of four related thesis projects aimed at developing a suite of software tools to collect, organize, and visualize empirical data about these "Kloosterman cardioids" to aid in the search for a rigorous mathematical explanation for their existence. In particular, this thesis project developed .NET software for visualization of Kloosterman cardioids, including methods for enhancing the cardioidal locus image for those values of p sufficiently large that the locus would otherwise be obscured due to the density of the O (p_) segments in the Kloosterman sum graph not contributing to the locus
This thesis documents the choreographic, music and film exploration for the performance /hōm\ presented on April 12-14, 2012 in the Studio Theater, ENS 200 at San Diego State University. Home has been the object of focus throughout this creative process. It has been through a collaborative dig and a purposeful structure, that a unique creative process has been developed. Included in this thesis is a documentation of the creation process, including sketches, photographs and film clips from the research and performance video. This thesis also serves as a complementary writing which includes locating the dance practice in a lineage of influences as well as providing a conceptual framework for the research that informs the project., San Diego State University
17 hr days
17 Hr Days is a body of work that re-creates physical and mental sensations experienced on construction job sites. The work evokes curiosity and discovery in exploring the transitory and incomplete spaces of a work site from the perspective of a child while simultaneously examining the patient and expert understanding of structures and the integrity of specific materials and processes. 17 Hr Days includes three sculptural objects and two installations comprised of materials familiar to conventional construction methods. The concept is realized through sculptural manifestations of experiences had on construction sites. Concrete, timber, string and steel are fashioned into structures which relate to the visual aesthetic of the construction field yet have no identifiable purpose. The act of exploring spaces, scrambling through piles of lumber, and the awe of jobsite systems are recreated as sculpture and installation for the viewer to explore in a gallery setting transforming the mundane jobsite into surreal environments of color, texture and process. The work encompasses the gallery structure itself, directing the viewer to consider the materials via a close lens. Installations pass through or cut an entry out of the gallery wall itself. The sculptures bring focus to the weight and tension affixed to walls or ceiling and hover with wavering stability above the floor. Questions of safety are present, causing one to weigh whether or not to explore details closer, or move back. This body of work was exhibited at the San Diego State University Gallery from May 5th to May 14th, 2015 and images of this thesis project are on file in the school of Art, Design, and Art History., San Diego State University
24-hours of heart health: An analysis of sleep duration and cardiovascular disease in the OPACH cohort
Background: Cardiovascular Disease (CVD) is the most prevalent chronic disease in the aging population. Older women are at greatest risk for CVD, higher than their male counterparts. Disparities in the incidence and prevalence of CVD and CVD risk factors in older women, suggest that current prevention strategies are not effective for these populations. Research shows that post menopausal women experience difficulty adapting to age-related changes in sleep. Considering 1/3 of the day is spent sleeping, sleep duration is a potential modifiable CVD lifestyle risk factor worthy of greater exploration. Aging research to date has included a focus on the cardiometabolic associations of sleep duration, including large-scale epidemiological studies and meta-analyses concluding that inadequate sleep duration and poor sleep quality are associated with increased development, progression, and severity of CVD and CVD comorbidities. Research, however, has mostly employed self-reported sleep measures, focused on Caucasian populations and has not considered sleep as part of the 24 hour day. There is a need for research to examine the relationship between sleep duration and CVD risk in an older population of women, and to determine if insufficient sleep duration, short or long, is a CVD risk factor worthy of further examination. Methods: This dissertation leverages data from the unique “Objective Physical Activity and Cardiovascular Health” (OPACH) study among 6489 women, ages 63-99, recruited from a Women’s Health Initiative cohort. Women wore ActiGraph GT3X+ accelerometers on the hip for 24 hours per day and completed a daily sleep log over a 7-day period. In addition to accelerometer-measured 24-hour activity data, the OPACH study includes measures of physical functioning, lifestyle questionnaires, and clinical biomarkers. Participants were contacted yearly to provide updated medical history including self-report of CVD events with follow-up up to 5 years. Sleep data were scored according to a standard protocol using sleep logs. Chapter 1 assessed if sleep duration, measured with accelerometers, is associated with numerous cardiometabolic markers, including measures of insulin resistance, inflammation and body composition in older women. Chapter 2 was an examination of the relationship between sleep duration and the Reynolds Risk Score, a clinically relevant composite CVD risk score. In Chapter 3, the relationship between cardiovascular events over 3-5 years of follow-up and self-reported sleep duration and accelerometer-measured sleep duration was examined. Results: Chapter 1 found significant associations between sleep duration and markers of cardiometabolic health. Several of these relationships suggested the relationship was u-shaped, with short and long sleep associated with higher cardiometabolic values. Chapter 2 further explored this relationship and demonstrated that sleep duration is non-linearly associated with 10-year estimated CVD risk among older women. In Chapter 3, there was no significant increase in CVD risk for short or long sleep durations over the 5-year period, measured by self-report or accelerometer. Discussion: The results of this analysis demonstrate sleep duration is related to markers of cardiometabolic health and intermediate CVD risk, but that sleep duration does not independently predict incident CVD. These findings may be explained by the interdependence of 24-hour activities, including sleep duration, and their relationship to cardiometabolic health. While results do not support sleep duration as a risk factor for CVD, they do support sleep duration as a lifestyle behavior worth targeting for cardiometabolic risk reduction in older women. To better understand how sleep relates to cardiometabolic health, we must better understand the interdependence and interrelationships of activities throughout the 24-hour day.
25 days, before antiquity; 33 nights - until infamy
This thesis is a disparate amalgam of poetry, prose, non-fictive, performance based & liminally concrete texts - aimed towards birthing new breeds of literature -- in a world where the word is continually reduced.
287(g) policy and public safety: A matched comparison multi-linear regression analysis
Includes bibliographical references (p. 51-55)., Ever-growing concern with immigration has increasingly become a vehicle for expanding the scope of the Department of Homeland Security and Immigration and Customs Enforcement. As part of this expansion, local law enforcement agencies are encouraged to enter into agreements with the federal government that allow them to act as federal agents for the enforcement of immigration law. This cooperative effort is known as the 287(g) program. The question addressed in this thesis is whether county-level agency participation in this program has demonstrated a statistically significant relationship with crime reduction from 2008 to 2010 when compared with county agencies not participating. After controlling for multiple intervening variables and executing multiple analyses, it was determined that only two of seven dependent variable (Motor Vehicle Theft and Burglary) categories showed such a negative relationship. Furthermore, upon conducting analyses excluding anomalous cases, it was concluded that these two relationships were dependent upon the inclusion of Los Angeles County in the sample. The significance of using a regression analysis to determine relationships between variables is to establish if policies are applying resources and enforcement to real problems. 287(g) claims to reduce crime and increase public safety through cooperation between local and federal agencies by removing criminal immigrant threats. This claim is not supported by the following analysis and opens the door for further research into effective policies for increasing public safety and for real immigration reform.
2D filtering based on voronoi fourier supports
The Empirical Wavelet Transform is an approach proposed to decompose a signal accordingly to its contained information, addressing the Empirical Mode Decomposition algorithm’s issues of nonlinearity and lack of mathematical theory. However, in the extension of the EWT algorithms into 2D, the wavelets are still based on a prescribed type of partitioning of the Fourier domain. In this thesis, we investigate the opportunity to rid the prescribed partitioning by first implementing scale-space theory inspired techniques to detect the position of the 2D harmonic modes, then partitioning the Fourier domain into Voronoi cells that will serve as supports to build empirical wavelet filters. We show the efficiency of the proposed approach in extracting different harmonic modes., San Diego State University
3-D printing of magnetic field responsive biomimetic structures
Additive manufacturing or 3-D printing is the process of creating a three-dimensional object from a 3-D digital model. In recent years, it has been used as a tool to help create structures that were too complex for traditional manufacturing methods. It also allows for the use of materials that have a variety of material properties that vary on strength, toughness, and ductility. Additive manufacturing can be used to create structures inspired from biology. 3-D printed materials with shape morphing capability that respond to external stimuli such as heat, light, and electricity have become known as 4-D printing. One such aspect of 4-D printing is the use of ferromagnetic nanoparticles in structures to increase the mechanical properties when a magnetic field is applied. In this study, 3-D printed honeycomb-based designs and crocodile-based armor designs incorporated ferromagnetic particles to increase material properties. The samples were fabricated by additive manufacturing using an elastic resin. There were three honeycomb-based structures, a traditional honeycomb, a bamboo-inspired honeycomb, and a pomelo-inspired honeycomb. All ferrofluid filled honeycomb structures exhibited an increase in effective stiffness when a magnetic field was applied. Further, the bamboo-inspired honeycomb was tested at different strengths of the magnetic field. The results showed that as the magnetic field decreased, the stiffness decreased. Finally, the crocodile-based armor design was tested and found that the ferromagnetic particles were practical in the application of a smart-armor by increasing the samples strength., San Diego State University
3D metal printed Ka-band waveguide polarizer and feed horn antenna
We are witnessing a phase where rapid progress is being made in research and development related to 5G Millimeter wave communication. Institutes and industries are working for realization and implementation of this technology. It is in this backdrop our research work focuses on development of antenna and polarizer component for one of the 5G millimeter wave frequency band (Ka-band). Objectives are to design and develop compact, low loss, wide-bandwidth and commercially viable i.e., low fabrication cost waveguide components for 5G millimeter wave frequencies. The last requirement can be met by utilizing 3D fabrication process and has been used in the current research. This thesis work involves the design and development of 3D printed polarizer and feed horn antenna at millimeter wave frequency. A highly compact circular waveguide based polarizer is designed at Ka-band. The design consists of a pair of radially opposite grooves located on the inner wall of waveguide. An equivalent model based on higher order mode analysis is developed to calculate the cutoff frequency of the modified structure. The cutoff frequency at different operating frequencies are calculated and compared with full wave simulation software HFSS to validate the model. The design is fabricated using direct metal laser sintering process. The fabricated polarizer has a measured 3dB axial ratio bandwidth from 28-34 GHz. The second design is related to 3D printed axial corrugated horn operating over the full Ka-band (26.5-40 GHz). The horn antenna consists of axial corrugations which makes the design very compact. The physical parameters of the corrugation such as step size and width are designed based on higher order mode coupling from the fundamental TE11 to TM11 and TE12 mode. This gives physical insight into the influence of design parameters on the radiation pattern. The designed horn is fabricated using 3D metal printing. Measured radiation patterns show good pattern symmetry and cross-polarization level better than 29 dB is achieved in the principal planes over the frequency band., San Diego State University
3D printing of bioinspired functional microstructures for use in fog collection
Fog collection represents an important source of supplemental liquid for many plants and animals located in arid climates. This is especially true in coastal arid climates, which receive very little rainfall, but have frequent fog banks during the winter months. Through evolution, these plants and animals have developed ways to collect fog and then transfer that collected liquid to a desired location. Thus, fog collection consists of two important aspects: the condensation of the liquid from the fog and the transportation of that liquid to a desired location. Manmade designs of fog collecting devices can draw inspiration from natural organisms in the condensation and transportation phase of fog collection. This process is called biomimicry or bioinspired design. In this study, a 3D printed fog collection device was fabricated and tested which utilized bioinspired design of cactus spines to condense liquid from fog and a series of microcavities within microchannels based off the pitcher plant Nepenthes Alata to transfer the liquid. The fabricated spines were tested for their fog collection efficiency, and the microchannels/microcavities were tested for their transportation speed. The manufacturing integrity of both structures created by 3D printing was analyzed. Finally, the integration of the two differing structures was tested to show the enhanced efficiency of a device utilizing both structures over devices using only one of the structures., San Diego State University