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Collection Description

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

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A Bridgerian age flora from Del Mar, California
A small but well-preserved transported assemblage of plant fossils collected from the middle Eocene Torrey Sandstone at Del Mar, California, provides, for the first time, an accurate picture of local climate and vegetation 49 to 50 Ma. The flora includes taxa from estuarine, riparian, and coastal lowland habitats of a paratropical broadleaf forest. Living taxa similar to Torrey flora species inhabit warm temperate to paratropical forests of southeastern China, Mexico, and the southeastern United States. The taxonomic composition and foliar physiognomy of Torrey flora fossils indicate a warm (20 C mean annual temperature), equable (less than 8 C mean annual temperature range), frostless climate, with annual rainfall of between 120 and 150 cm, concentrated during the months of April through September. These conclusions suggest that although a climatic drying trend was well established in western North America as early as 50 Ma, conditions remained mesic in the coastal San Diego region. The occurrence of tropical taxa including Tabernaemontana and Eugenia americana in the Torrey flora indicate that the mean annual temperature of the San Diego area had increased between early and middle Eocene time., San Diego State University
A DSpace mobile theme for San Diego State University
Includes bibliographical references (pages 54-55)., DSpace is the most widely used open source repository platform and is popular in different fields like academic, research center, health, government, museums, national libraries and so on. More than hundred countries and over 1500 institutions now use DSpace. San Diego State University's digital collection of Theses and Dissertations runs on DSpace. This thesis is an attempt to install and customize a DSpace mobile theme for San Diego State University. The work also includes development of additional features like adding navigational bars, adding administrative login capabilities, accessing administrative navigational panel via mobile theme. The mobile theme supports other features like search, advanced search, recent submissions, submissions and workflow. With the widespread use of mobile telephony, providing a mobile theme for SDSU DSpace will reach out to faculty and other interested parties.
A Geant4 model of backscatter security imaging systems
The operating characteristics of x ray security scanner systems that utilize backscatter signal in order to distinguish person borne threats have never been made fully available to the general public. By designing a model using Geant4, studies can be performed which will shed light on systems such as security scanners and allow for analysis of the performance and safety of the system without access to any system data. Despite the fact that the systems are no longer in use at airports in the United States, the ability to design and validate detector models and phenomena is an important capability that can be applied to many current real world applications. The model presented provides estimates for absorbed dose, effective dose and dose depth distribution that are comparable to previously published work and explores imaging capabilities for the system embodiment modeled.
A KdV-SIR equation and analytical solutions: Relationship to the non-dissipative Lorenz model and an application for COVID-19 data analysis
Accurate predictions for the spread and evolution of epidemics have significant societal and economic impacts. The temporal evolution of infected (or dead) persons has been described as an epidemic wave with an isolated peak and tails. Epidemic waves have been simulated and studied using the classical SIR model that describes the evolution of susceptible (S), infected (I), and recovered (R) individuals. To illustrate the fundamental dynamics of an epidemic wave, the dependence of solutions on parameters, and the dependence of predictability horizons on various types of solutions, Paxson and Shen (2022c, IJBC) [35] proposed a Korteweg-de Vries (KdV)-SIR equation and obtained analytical solutions. I will first introduce the KdV-SIR equation and discuss its relationship to the non-dissipative Lorenz model. I then illustrate how the KdV-SIR equation and its analytical solutions were applied for the estimates of predictability horizons using the COVID-19 data from the USA. The KdV-SIR model is mathematically identical to the non-dissipative Lorenz 1963 model and the KdV equation in a traveling-wave coordinate. As a result, the dynamics of an epidemic wave and its predictability can be understood by applying approaches used in nonlinear dynamics, and by comparing the aforementioned systems. For example, a typical solitary wave solution is a homoclinic orbit that connects a stable and an unstable manifold at the saddle point within the I - I’ space. The KdV-SIR equation additionally produces two other types of solutions, including oscillatory and unbounded solutions. The analysis of two critical points reveals the features of solutions near a turning point. Using analytical solutions and hypothetical observed data, a simple formula was derived for determining a predictability horizon (i.e., the timing for the peak of an epidemic wave). The above procedures were then applied to the real world COVID-19 data from the USA. To illustrate the effectiveness of the procedures in real data application, raw data were first processed using a Fast Fourier Transform (FFT), the empirical mode decomposition (EMD) method or the 28-days running mean methods. For analysis, smooth data were then used to generate ensemble predictions., San Diego State University
A Kosovar nation: Heroes, education, diaspora and the (re)imagining of Kosovar nationhood
Includes bibliographical references (p. 60-67)., This thesis begins with the argument that nations should not be treated as real, substantial, and enduring collectivities rooted in an antiquated-ethnic past. Instead it argues that nations and nationalism are distinctly modern and should be viewed through a categorical lens; that they are best understood as a process that requires an examination of how nationhood is institutionalized, how it works as a practical category, and can be the product of a perennial happening; and that nationness is fluctuating and works as an ambiguous and yet resonating symbol that attracts a degree of emotional loyalty to those who believe they constitute it. From this understanding of nationalism, it then argues that the Republic of Kosovo, in seeking to build or maintain its legitimacy, asserts itself as the authoritative spokesman of the nation by appropriating national heroes, working to institutionalize a distinct understanding of nationhood, and courting members of the Kosovar diaspora. In doing so, I seek two problematize two widely held notions: the notion that (new) 'nations' are a thing of the past and the belief that statehood is the capstone of the nationalist project. Rather, I show that the modern era has not precluded the formation of new nations and that 'culmination' of the nationalist project, statehood, is but the conclusion of a chapter that introduces the state as the primary actor in the promotion of nationalism.
A Mac layer protocol for wireless ad-hoc networks using directional antenna
Using directional antenna in ad hoc networks, offer many benefits in contrast to their classical omni-directional counterparts. The most important benefits are the significant improvement in spatial reuse, reduction of the radio interference, increase in coverage range and subsequently an increase in network capacity on the whole. On the other hand, directional transmission increases the hidden terminal problem and the problem of deafness. To best utilize directional antennas, a suitable Medium Access Control (MAC) protocol must be designed. Current MAC protocols, such as the IEEE 802.11 standard for Wireless LANs, assume the omni-directional antenna at its Physical layer and thus do not fully exploit the capabilities of a directional antenna. In this thesis, we propose a MAC protocol for wireless ad hoc networks which fully exploits the potentials of directional antennas. The first part of our design studies the issues related to directional MAC protocols and we use this knowledge to carefully design the proposed MAC protocol for ad hoc networks using directional antennas. We evaluate our work through simulation studies performed on the network simulator — NS2. Numerical results obtained are promising and show that our protocol offers significant improvement in throughput when compared to the performance of traditional 802.11 MAC protocol and D-MAC which is a Directional MAC protocol for ad hoc networks.
A Monte Carlo simulation of the Compton camera
The problems inherent to High energy photon imaging require alternate modes of collimation. Whereas the gamma camera's physical collimator typically reduces the intensity of the photons by more than 99.9%. The Compton camera achieves higher sensitivity by using the photons which are no longer required to pass through a physical collimator. The sensitivity of the Compton Camera has been shown to be 2 to 3 orders of magnitude larger than the sensitivity of a physically collimated gamma Camera. The electronic collimation is inherently 3D and is inherently suited for tomography. Software was developed as part of this thesis to process MCNPX-PTRAC output to simulate a triple Compton scatter camera in the range of 140 keV to 511 keV. The results of the simulations demonstrated the effects of varying detector's design parameters such as energy and spatial resolution. The inaccuracies in the Monte Carlo MCNPX software in particular with respect to the Doppler broadening subroutines were noted and discussed., San Diego State University
A SINR based MAC layer protocol for multi-channel ad-hoc networks
A SINR based MAC layer protocol for multi-channel ad-hoc networks is proposed. The protocol provides a distributed solution to a node pair that has to choose the "best" channel amongst the available 'M' channels (M>1). We define "best channel selection" in terms of the least interference power measurement encountered on a particular channel by the receiving station throughout the entire duration of data exchange. Using Medium Access Control (MAC) layer mechanisms for message exchange between the nodes, our algorithm achieves not only interference mitigation but also solves the classical hidden and exposed terminal problems in wireless networks. Simulations performed on the NS-2 platform validate the throughput gain achieved by our algorithm in comparison to IEEE 802.11 MAC scheme alongside two other state-of-the-art multichannel MAC protocols.
A Yuman digital library: The Takuk bird song cycle archives of the Ipai, Kumeyaay, Tipay(Tipai) people of Baja California, Mexico, and California, USA
Universities from 1900 to 1970 have recorded many indigenous communities in the United States. It was always published by an outsider. My goal is to give insight from a community called Ipai-Kumeyaay-Tipay. Our stories have been told by strangers who did not know the language and recorded based on orthography. I have listened to every singer from 1900 to 2021. My goal today is to show you how we are one and still one. All Yuman speakers were all made on Spirit Mountain. I have created a digital library told by us, for us, and those to come., San Diego State University