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- Title
- A multi-scale approach to study Solid Oxide Fuel Cells: from Mechanical Properties and Crystal Structure of the Cell's Materials to the Development of an Interactive and Interconnected Educational Tool.
- Creator
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Aman, Amjad, Orlovskaya, Nina, Xu, Yunjun, Das, Tuhin, University of Central Florida
- Abstract / Description
-
Solid Oxide Fuel Cells are energy conversion devices that convert chemical energy of a fuel directly into electrical energy. They are known for being fuel-flexible, have minimal harmful emissions, ideal for combined heat and power applications, highly energy-efficient when combined with gas or steam turbines. The current challenges facing the widespread adoption these fuel cells include cost reduction, long-term testing of fully integrated systems, improving the fuel cell stack and system...
Show moreSolid Oxide Fuel Cells are energy conversion devices that convert chemical energy of a fuel directly into electrical energy. They are known for being fuel-flexible, have minimal harmful emissions, ideal for combined heat and power applications, highly energy-efficient when combined with gas or steam turbines. The current challenges facing the widespread adoption these fuel cells include cost reduction, long-term testing of fully integrated systems, improving the fuel cell stack and system performance, and studies related to reliability, robustness and durability. The goal of this dissertation is to further the understanding of the mechanical properties and crystal structure of materials used in the cathode and electrolyte of solid oxide fuel cells, as well as to report on the development of a supplementary educational tool that could be used in course related to fuel cells. The first part of the dissertation relates to the study of LaCoO3 based perovskites that are used as cathode material in solid oxide fuel cells and in other energy-related applications. In-situ neutron diffraction of LaCoO3 perovskite during uniaxial compression was carried out to study crystal structure evolution and texture development. In this study, LaCoO3 was subjected to two cycles of uniaxial loading and unloading with the maximum stress value being 700-900 MPa. The in-situ neutron diffraction revealed the dynamic crystallographic changes occurring which is responsible for the non-linear ferroelastic deformation and the appearance of hysteresis in LaCoO3. At the end of the first cycle, irreversible strain was observed even after the load was removed, which is caused by non-recoverable domain reorientation and texture development. At the end of the second cycle, however, no irreversible strain was observed as domain reorientation seemed fully recovered. Elastic constants were calculated and Young's modulus was estimated for LaCoO3 single crystals oriented along different crystallographic directions. The high temperature mechanical behavior study of LaCoO3 based perovskites is also of prime importance as solid oxide fuel cells operate at high temperatures. Incidentally, it was observed that as opposed to the behavior of most materials, LaCoO3 exhibits stiffening between 700 oC to 900 oC, with the Young's modulus going from a value of ~76 GPa at room temperature to ~120 GPa at 900 oC. In-situ neutron diffraction, XRD and Raman spectroscopy were used to study structural changes occurring in the material as it was heated. The results from these experiments will be discussed.The next portion of the dissertation will focus on electrolytes. Numerical simulation was carried out in order to predict the non-linear load-stress relationship and estimation of biaxial flexure strength in layered electrolytes, during ring-on-ring mechanical testing.Finally, the development of an interactive and inter-connected educational software is presented that could serve as a supplementary tool to teach fuel cell related topics.
Show less - Date Issued
- 2016
- Identifier
- CFE0006436, ucf:51467
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006436
- Title
- Study On Anisotropic Plasticity And Fracture Of Lightweight Metal Sheets.
- Creator
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Jia, Yueqian, Bai, Yuanli, Kassab, Alain, Raghavan, Seetha, Gou, Jihua, Wu, Thomas, University of Central Florida
- Abstract / Description
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How to reduce weight and increase fuel efficiency is a critical challenge in transportation industries. One way to resolve the problem is to adopting lightweight alloys (i.e. advanced high strength steel, aluminum alloys, or magnesium alloy) in structure designs and manufacturing. Fully understanding the mechanical properties of these materials is a key step.In order to fully characterize the plasticity and fracture of magnesium AZ31B-H24 sheets, a set of mechanical experiments (170 in total)...
Show moreHow to reduce weight and increase fuel efficiency is a critical challenge in transportation industries. One way to resolve the problem is to adopting lightweight alloys (i.e. advanced high strength steel, aluminum alloys, or magnesium alloy) in structure designs and manufacturing. Fully understanding the mechanical properties of these materials is a key step.In order to fully characterize the plasticity and fracture of magnesium AZ31B-H24 sheets, a set of mechanical experiments (170 in total) were performed under both monotonic and non-proportional loading conditions, including monotonic uniaxial tension, notch tension, in-plane uniaxial compression, wide compression (or called biaxial compression), plane strain compression, through-thickness compression, in-plane shear, punch test, uniaxial compression-tension reverse loading, and two-step uniaxial tension (cross-loading).Both the plastic strain histories and stress responses were obtained under the above loading conditions, which give a comprehensive picture of mechanical behaviors of this material. No apparent cross-hardening effect was observed for this material.An extended orthotropic yield criterion involving two linear anisotropic transformation tensors, CPB06ex2, in conjunction with its associated flow rule was fully calibrated to describe both the anisotropy in plastic flow and tension-compression asymmetry in stress-strain behaviors.A fully modularized framework to combine isotropic, kinematic, and cross hardening behaviors was established under non-monotonic loading conditions. Three sets of state variables were defined and applied to consider the effects of, a) loading history, b) twinning and de-twinning and c) different pre-strain.In order to predict ductile fracture of metal sheets, the (")mixed(") stress/strain invariants based Modified-Mohr-Coulomb (MMC) fracture model was transferred into an all-strain based MMC (eMMC) model under plane stress condition, predicting the fracture strain dependent on strain ratio or ? angle, instead of stress triaxiality and Lode angle parameter. The strain ratio or ? angle could be directly measured by digital image correlation (DIC), while the latter required finite element analysis to be determined. This method makes it possible to study material fracture behavior while bypassing plasticity. The eMMC fracture locus can be fully calibrated by fracture strains directly measured from DIC. The fracture strain was also extended by a linear transformation operating to the plastic strain tensor to incorporate the fracture anisotropy. All models were implemented into Abaqus/Explicit as a user material subroutine (VUMAT). Good prediction capability has been demonstrated for magnesium AZ31B-H24 sheets by FE simulation using shell elements.The current framework was also applied for TRIP780, BH240, DP600, and EDDQ steel sheets with adjustment, under different loading conditions. The FE simulation results for TRIP780 correlated well with experimental data under different monotonic loading conditions. The analytical results for BH240, DP600, and EDDQ demonstrated good prediction capability for cross-hardening behavior, and validated by the non-proportional experimental data under two-stage uniaxial tension.
Show less - Date Issued
- 2016
- Identifier
- CFE0006121, ucf:51165
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006121
- Title
- Hmong Americans in Higher Education: Exploring their Sense of Belongingness and the Concept of the American Dream.
- Creator
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Daugherty, Janet, Cintron Delgado, Rosa, Owens, J. Thomas, Cox, Thomas, Molina, Olga, University of Central Florida
- Abstract / Description
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I conducted this study to examine Hmong American college students' perspectives on sense of belongingness and their idea on the American Dream. The college experience can serve as a precursor to improving the social and economic situation of the Hmong students when aligned with the personal desire to gain upward mobility and motivation to circumvent social and academic inconsistencies.The methodology of the study was designed for one-on-one phenomenological informal interviews with Hmong...
Show moreI conducted this study to examine Hmong American college students' perspectives on sense of belongingness and their idea on the American Dream. The college experience can serve as a precursor to improving the social and economic situation of the Hmong students when aligned with the personal desire to gain upward mobility and motivation to circumvent social and academic inconsistencies.The methodology of the study was designed for one-on-one phenomenological informal interviews with Hmong American college upper-classmen using a two-part interview protocol to elicit demographic and experiential information. Moustakas' approach to the analysis of data provided guidelines to review individual transcripts and to group, remove, cluster, and thematize lived experiences.The findings of this study indicated that Hmong college students: (a) enrolled out of obedience to the parents, especially their fathers, regardless of the educational level of the parents and (b) thrived when authority figures on campus reached out to help their humble situation. . . it not only made them belong to the campus family but it strengthened their self-esteem.
Show less - Date Issued
- 2015
- Identifier
- CFE0005596, ucf:50250
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005596
- Title
- Specialty Fiber Lasers and Novel Fiber Devices.
- Creator
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Jollivet, Clemence, Schulzgen, Axel, Moharam, Jim, Richardson, Martin, Mafi, Arash, University of Central Florida
- Abstract / Description
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At the Dawn of the 21st century, the field of specialty optical fibers experienced a scientific revolution with the introduction of the stack-and-draw technique, a multi-steps and advanced fiber fabrication method, which enabled the creation of well-controlled micro-structured designs. Since then, an extremely wide variety of finely tuned fiber structures have been demonstrated including novel materials and novel designs. As the complexity of the fiber design increased, highly-controlled...
Show moreAt the Dawn of the 21st century, the field of specialty optical fibers experienced a scientific revolution with the introduction of the stack-and-draw technique, a multi-steps and advanced fiber fabrication method, which enabled the creation of well-controlled micro-structured designs. Since then, an extremely wide variety of finely tuned fiber structures have been demonstrated including novel materials and novel designs. As the complexity of the fiber design increased, highly-controlled fabrication processes became critical. To determine the ability of a novel fiber design to deliver light with properties tailored according to a specific application, several mode analysis techniques were reported, addressing the recurring needs for in-depth fiber characterization. The first part of this dissertation details a novel experiment that was demonstrated to achieve modal decomposition with extended capabilities, reaching beyond the limits set by the existing mode analysis techniques. As a result, individual transverse modes carrying between ~0.01% and ~30% of the total light were resolved with unmatched accuracy. Furthermore, this approach was employed to decompose the light guided in Large-Mode Area (LMA) fiber, Photonic Crystal Fiber (PCF) and Leakage Channel Fiber (LCF). The single-mode performances were evaluated and compared. As a result, the suitability of each specialty fiber design to be implemented for power-scaling applications of fiber laser systems was experimentally determined.The second part of this dissertation is dedicated to novel specialty fiber laser systems. First, challenges related to the monolithic integration of novel and complex specialty fiber designs in all-fiber systems were addressed. The poor design and size compatibility between specialty fibers and conventional fiber-based components limits their monolithic integration due to high coupling loss and unstable performances. Here, novel all-fiber Mode-Field Adapter (MFA) devices made of selected segments of Graded Index Multimode Fiber (GIMF) were implemented to mitigate the coupling losses between a LMA PCF and a conventional Single-Mode Fiber (SMF), presenting an initial 18-fold mode-field area mismatch. It was experimentally demonstrated that the overall transmission in the mode-matched fiber chain was increased by more than 11 dB (the MFA was a 250 ?m piece of 50 ?m core diameter GIMF). This approach was further employed to assemble monolithic fiber laser cavities combining an active LMA PCF and fiber Bragg gratings (FBG) in conventional SMF. It was demonstrated that intra-cavity mode-matching results in an efficient (60%) and narrow-linewidth (200 pm) laser emission at the FBG wavelength.In the last section of this dissertation, monolithic Multi-Core Fiber (MCF) laser cavities were reported for the first time. Compared to existing MCF lasers, renown for high-brightness beam delivery after selection of the in-phase supermode, the present new generation of 7-coupled-cores Yb-doped fiber laser uses the gain from several supermodes simultaneously. In order to uncover mode competition mechanisms during amplification and the complex dynamics of multi-supermode lasing, novel diagnostic approaches were demonstrated. After characterizing the laser behavior, the first observations of self-mode-locking in linear MCF laser cavities were discovered.
Show less - Date Issued
- 2014
- Identifier
- CFE0005354, ucf:50491
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005354
- Title
- The Effects of State Leader Psychology on Civil War Lethality.
- Creator
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Kelley, Brandon, Vasquez, Joseph, Dolan, Thomas, Schafer, Mark, University of Central Florida
- Abstract / Description
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Does a state leader's psychology influence lethality in civil wars? This thesis analyzes the aforementioned question during post-1945 civil wars. This particular subject, paying close attention to individual psychology at the state level, is gaining traction amongst scholars, though limited scholarly attention has addressed whether leader psychology is an indicator of conflict severity in terms of lethality. The psychology of the state leader in this thesis is assessed from leadership traits...
Show moreDoes a state leader's psychology influence lethality in civil wars? This thesis analyzes the aforementioned question during post-1945 civil wars. This particular subject, paying close attention to individual psychology at the state level, is gaining traction amongst scholars, though limited scholarly attention has addressed whether leader psychology is an indicator of conflict severity in terms of lethality. The psychology of the state leader in this thesis is assessed from leadership traits and operational code indices, specifically direction of strategy (I1) and interpretation of the nature of the political universe (P1). The data and cases used are pulled from datasets by Dr. James Fearon and the Correlates of War Project. The leaders' speech content is derived primarily from prepared material and analyzed using verbal content analysis via Profiler Plus. In measuring the effects of the predictors on my dependent variable, I chose the methodological approach of count data models, specifically, zero-truncated negative binomial regression. The results from the eight models I ran show that specific psychological traits, particularly a leader's I1 and P1 scores, level of distrust, and need for power, do play a significant role when determining the causes of civil war lethality.
Show less - Date Issued
- 2014
- Identifier
- CFE0005358, ucf:50469
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005358
- Title
- Treatment Matching in PTSD: A Confirmatory Factor Analysis Based On Therapeutic Mechanisms of Action.
- Creator
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Trachik, Benjamin, Bowers, Clint, Beidel, Deborah, Jentsch, Florian, University of Central Florida
- Abstract / Description
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The current study takes an initial step toward deriving a method for empirically based, theory-driven treatment matching in a military population suffering from PTSD. Along with the more overt symptoms of PTSD (e.g., persistent hyperarousal), secondary cognitive symptoms have also been shown to be significantly associated with avoidance and intrusive symptoms, as well as contribute to functional impairment. Based on the factor analytic and treatment literature for PTSD, it appears that there...
Show moreThe current study takes an initial step toward deriving a method for empirically based, theory-driven treatment matching in a military population suffering from PTSD. Along with the more overt symptoms of PTSD (e.g., persistent hyperarousal), secondary cognitive symptoms have also been shown to be significantly associated with avoidance and intrusive symptoms, as well as contribute to functional impairment. Based on the factor analytic and treatment literature for PTSD, it appears that there are two central mechanisms associated with beneficial therapeutic change that underlies both CPT and PE treatments (i.e., habituation, changes in cognitions). Additionally, different traumatic events and peritraumatic responses may be associated with unique symptom profiles and may necessitate targeted treatment. The present study proposes a novel approach to treatment matching based on the factor structure of PTSD and underlying mechanisms of treatment response. More broadly, this paper provides evidence for a broader understanding of peritraumatic responses and the potential implications of these responses for symptom profiles and illness trajectories.
Show less - Date Issued
- 2014
- Identifier
- CFE0005727, ucf:50126
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005727
- Title
- Uncovering The Sub-Text: Presidents' Emotional Expressions and Major Uses of Force.
- Creator
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Assaf, Elias, Houghton, David, Kim, Myunghee, Dolan, Thomas, University of Central Florida
- Abstract / Description
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The global context of decision making continues to adapt in response to international threats. Political psychologists have therefore considered decision making processes regarding major uses of force a key area of interest. Although presidential personality has been widely studied as a mitigating factor in the decision making patterns leading to uses of force, traditional theories have not accounted for the emotions of individuals as they affect political actions and are used to frame public...
Show moreThe global context of decision making continues to adapt in response to international threats. Political psychologists have therefore considered decision making processes regarding major uses of force a key area of interest. Although presidential personality has been widely studied as a mitigating factor in the decision making patterns leading to uses of force, traditional theories have not accounted for the emotions of individuals as they affect political actions and are used to frame public perception of the use of force. This thesis therefore measures expressed emotion and cognitive expressions in the form of expressed aggression, passivity, blame, praise, certainty, realism, and optimism as a means of predicting subsequent major uses of force. Since aggression and blame are precipitated by anger and perceived vulnerability, they are theorized to foreshadow increased uses of force (Gardner and Moore 2008). Conversely, passivity and praise are indicative of empathy and joy respectively, and are not expected to precede aggressive behavior conducted to maintain emotional regulation (Roberton, Daffer, and Bucks 2012). Additionally, the three cognitive variables of interest expand on existing literature on beliefs and decision making expounded by such authors as Walker (2010), Winter (2003) and Hermann (2003). DICTION 6.0 is used to analyze all text data of presidential news conferences, candidate debates, and State of the Union speeches given between 1945 and 2000 stored by The American Presidency Project (Hart and Carroll 2012). Howell and Pevehouse's (2005) quantitative assessment of quarterly U.S. uses of force between 1945 and 2000 is employed as a means of quantifying instances of major uses of force. Results show systematic differences among the traits expressed by presidents, with most expressions staying consistent across spontaneous speech contexts. Additionally, State of the Union speeches consistently yielded the highest scores across the expressed traits measured; supporting the theory that prepared speech is used to emotionally frame situations and setup emotional interpretations of events to present to the public. Time sensitive regression analyses indicate that expressed aggression within the context of State of the Union Addresses is the only significant predictor of major uses of force by the administration. That being said, other studies may use the comparative findings presented herein to further establish a robust model of personality that accounts for individual dispositions toward emotional expression as a means of framing the emotional interpretation of events by audiences.
Show less - Date Issued
- 2014
- Identifier
- CFE0005300, ucf:50513
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005300
- Title
- The Identification and Segmentation of Astrocytoma Prior to Critical Mass, by means of a Volumetric/Subregion Regression Analysis of Normal and Neoplastic Brain Tissue.
- Creator
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Higgins, Lyn, Hughes, Charles, Morrow, Patricia Bockelman, Bagci, Ulas, Lisle, Curtis, University of Central Florida
- Abstract / Description
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As the underlying cause of Glioblastoma Multiforme (GBM) is presently unclear, this research implements a new approach to identifying and segmenting plausible instances of GBM prior to critical mass. Grade-IV Astrocytoma, or GBM, is an aggressive and malignant cancer arising from star-shaped glial cells, or astrocytes, where the astrocytes, functionally, assist in the support and protection of neurons within the central nervous system and spinal cord. Subsequently, our motivation for...
Show moreAs the underlying cause of Glioblastoma Multiforme (GBM) is presently unclear, this research implements a new approach to identifying and segmenting plausible instances of GBM prior to critical mass. Grade-IV Astrocytoma, or GBM, is an aggressive and malignant cancer arising from star-shaped glial cells, or astrocytes, where the astrocytes, functionally, assist in the support and protection of neurons within the central nervous system and spinal cord. Subsequently, our motivation for researching the ability to recognize GBM is that the underlying cause of the mutation is presently unclear, leading to the operative that GBM is only detectable through a combination of MRI and CT brain scans, cooperatively, along with a resection biopsy. Since astrocytoma only becomes evident at critical mass, when the cellular structure of the neoplasm becomes visible within the image, this research seeks to achieve earlier identification and segmentation of the neoplasm by evaluating the malignant area via a volumetric voxel approach to removing noise artifacts and analyzing voxel differentials. In order to investigate neoplasm continuity, a differential approach has been implemented utilizing a multi-polynomial/multi-domain regression algorithm, thus, ultimately, providing a graphical and mathematical analysis of the differentials within critical mass and non-critical mass images. Given these augmentations to MRI and CT image rectifications, we theorize that our approach will improve on astrocytoma recognition and segmentation, along with achieving greater accuracy in diagnostic evaluations of the malignant area.
Show less - Date Issued
- 2018
- Identifier
- CFE0007336, ucf:52111
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007336
- Title
- Sampling and Subspace Methods for Learning Sparse Group Structures in Computer Vision.
- Creator
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Jaberi, Maryam, Foroosh, Hassan, Pensky, Marianna, Gong, Boqing, Qi, GuoJun, Pensky, Marianna, University of Central Florida
- Abstract / Description
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The unprecedented growth of data in volume and dimension has led to an increased number of computationally-demanding and data-driven decision-making methods in many disciplines, such as computer vision, genomics, finance, etc. Research on big data aims to understand and describe trends in massive volumes of high-dimensional data. High volume and dimension are the determining factors in both computational and time complexity of algorithms. The challenge grows when the data are formed of the...
Show moreThe unprecedented growth of data in volume and dimension has led to an increased number of computationally-demanding and data-driven decision-making methods in many disciplines, such as computer vision, genomics, finance, etc. Research on big data aims to understand and describe trends in massive volumes of high-dimensional data. High volume and dimension are the determining factors in both computational and time complexity of algorithms. The challenge grows when the data are formed of the union of group-structures of different dimensions embedded in a high-dimensional ambient space.To address the problem of high volume, we propose a sampling method referred to as the Sparse Withdrawal of Inliers in a First Trial (SWIFT), which determines the smallest sample size in one grab so that all group-structures are adequately represented and discovered with high probability. The key features of SWIFT are: (i) sparsity, which is independent of the population size; (ii) no prior knowledge of the distribution of data, or the number of underlying group-structures; and (iii) robustness in the presence of an overwhelming number of outliers. We report a comprehensive study of the proposed sampling method in terms of accuracy, functionality, and effectiveness in reducing the computational cost in various applications of computer vision. In the second part of this dissertation, we study dimensionality reduction for multi-structural data. We propose a probabilistic subspace clustering method that unifies soft- and hard-clustering in a single framework. This is achieved by introducing a delayed association of uncertain points to subspaces of lower dimensions based on a confidence measure. Delayed association yields higher accuracy in clustering subspaces that have ambiguities, i.e. due to intersections and high-level of outliers/noise, and hence leads to more accurate self-representation of underlying subspaces. Altogether, this dissertation addresses the key theoretical and practically issues of size and dimension in big data analysis.
Show less - Date Issued
- 2018
- Identifier
- CFE0007017, ucf:52039
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007017
- Title
- Using Hashtags to Disambiguate Aboutness in Social Media Discourse: A Case Study of #OrlandoStrong.
- Creator
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DeArmas, Nicholas, Vie, Stephanie, Salter, Anastasia, Beever, Jonathan, Dodd, Melissa, Wheeler, Stephanie, University of Central Florida
- Abstract / Description
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While the field of writing studies has studied digital writing as a response to multiple calls for more research on digital forms of writing, research on hashtags has yet to build bridges between different disciplines' approaches to studying the uses and effects of hashtags. This dissertation builds that bridge in its interdisciplinary approach to the study of hashtags by focusing on how hashtags can be fully appreciated at the intersection of the fields of information research, linguistics,...
Show moreWhile the field of writing studies has studied digital writing as a response to multiple calls for more research on digital forms of writing, research on hashtags has yet to build bridges between different disciplines' approaches to studying the uses and effects of hashtags. This dissertation builds that bridge in its interdisciplinary approach to the study of hashtags by focusing on how hashtags can be fully appreciated at the intersection of the fields of information research, linguistics, rhetoric, ethics, writing studies, new media studies, and discourse studies. Hashtags are writing innovations that perform unique digital functions rhetorically while still hearkening back to functions of both print and oral rhetorical traditions. Hashtags function linguistically as indicators of semantic meaning; additionally, hashtags also perform the role of search queries on social media, retrieving texts that include the same hashtag. Information researchers refer to the relationship between a search query and its results using the term (")aboutness(") (Kehoe and Gee, 2011). By considering how hashtags have an aboutness, the humanities can call upon information research to better understand the digital aspects of the hashtag's search function. Especially when hashtags are used to organize discourse, aboutness has an effect on how a discourse community's agendas and goals are expressed, as well as framing what is relevant and irrelevant to the discourse. As digital activists increasingly use hashtags to organize and circulate the goals of their discourse communities, knowledge of ethical strategies for hashtag use will help to better preserve a relevant aboutness for their discourse while enabling them to better leverage their hashtag for circulation. In this dissertation, through a quantitative and qualitative analysis of the Twitter discourse that used #OrlandoStrong over the five-month period before the first anniversary of the Pulse shooting, I trace how the #OrlandoStrong discourse community used innovative rhetorical strategies to combat irrelevant content from ambiguating their discourse space. In Chapter One, I acknowledge the call from scholars to study digital tools and briefly describe the history of the Pulse shooting, reflecting on non-digital texts that employed #OrlandoStrong as memorials in the Orlando area. In Chapter Two, I focus on the literature surrounding hashtags, discourse, aboutness, intertextuality, hashtag activism, and informational compositions. In Chapter Three, I provide an overview of the stages of grounded theory methodology and the implications of critical discourse analysis before I detail how I approached the collection, coding, and analysis of the #OrlandoStrong Tweets I studied. The results of my study are reported in Chapter Four, offering examples of Tweets that were important to understanding how the discourse space became ambiguous through the use of hashtags. In Chapter Five, I reflect on ethical approaches to understanding the consequences of hashtag use, and then I offer an ethical recommendation for hashtag use by hashtag activists. I conclude Chapter Five with an example of a classroom activity that allows students to use hashtags to better understand the relationship between aboutness, (dis)ambiguation, discourse communities, and ethics. This classroom activity is provided with the hope that instructors from different disciplines will be able to provide ethical recommendations to future activists who may benefit from these rhetorical strategies.
Show less - Date Issued
- 2018
- Identifier
- CFE0007322, ucf:52136
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007322
- Title
- Recruiting Followers for the Caliphate: A Narrative Analysis of Four Jihadist Magazines.
- Creator
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Madrazo, Andrea, Matusitz, Jonathan, Malala, John, Sellnow, Timothy, University of Central Florida
- Abstract / Description
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This study identifies and compares the methods of recruitment used by three prime jihadist organizations through their online magazines. The successful recruitment efforts and growth as a threat by the Islamic State of Iraq and Sh?m (ISIS), Al-Qaeda, and Al-Shabaab are attributed, in part, to the widespread popularity and accessibility of Dabiq and Rumiyah (published by ISIS), Inspire (published by Al-Qaeda), and Gaidi Mtaani (published by Al-Shabaab). In order to best examine the techniques...
Show moreThis study identifies and compares the methods of recruitment used by three prime jihadist organizations through their online magazines. The successful recruitment efforts and growth as a threat by the Islamic State of Iraq and Sh?m (ISIS), Al-Qaeda, and Al-Shabaab are attributed, in part, to the widespread popularity and accessibility of Dabiq and Rumiyah (published by ISIS), Inspire (published by Al-Qaeda), and Gaidi Mtaani (published by Al-Shabaab). In order to best examine the techniques of persuasion and propaganda to recruit new followers, the theoretical approach of compliance-gaining theory and methodological approach of a narrative analysis are applied. The author analyzed a total of twelve magazine issues to compare how the four magazines use (1) imagery, (2) attrition, (3) intimidation, (4) propaganda, (5) spoiling, (6) outbidding, (7) incitement, and (8) recruitment. To validate each of these themes, the study applies an open-coding instrument to select each label based on specific dimensions. These findings reveal how the same purpose to achieve the Caliphate can be chosen on a similar path by these three different jihadist organizations. This path may take different turns at certain spots, but ultimately the road is based on the same historical context to justify the recruitment process. Overall, this study provides fresh descriptive insights on jihadist organizations' recruitment methods to gain new followers toward the achievement of the Caliphate (i.e., the global Islamic state). The sample reveals that the online jihadist magazines integrate all analyzed themes to portray their messages. The findings show certain issues implement specific themes more than others. Across the sample, the use of persuasion justified and encouraged violence. Persuasion is found in prideful examples of successful terrorist attacks and aftermath scenes of destruction. The distinct difference between the four online jihadist magazines is the persuasion of recruitment.
Show less - Date Issued
- 2018
- Identifier
- CFE0007048, ucf:51984
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007048
- Title
- Design, Development, and Testing of a Miniature Fixture for Uniaxial Compression of Ceramics Coupled with In-Situ Raman Spectrometer.
- Creator
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Jordan, Ryan, Orlovskaya, Nina, Kwok, Kawai, Ghosh, Ranajay, University of Central Florida
- Abstract / Description
-
This thesis is about the design, development and integration of an in-situ compression stage which interfaces through the Leica optical microscope coupled with a Renishaw InVia micro-Raman spectrometer. This combined compression stage and Raman system will enable structural characterization of ceramics and ceramic composites. The in-situ compression stage incorporates a 440C stainless steel structural components, 6061 aluminum frame, a NEMA 23 stepper motor. Two load screws that allow to...
Show moreThis thesis is about the design, development and integration of an in-situ compression stage which interfaces through the Leica optical microscope coupled with a Renishaw InVia micro-Raman spectrometer. This combined compression stage and Raman system will enable structural characterization of ceramics and ceramic composites. The in-situ compression stage incorporates a 440C stainless steel structural components, 6061 aluminum frame, a NEMA 23 stepper motor. Two load screws that allow to apply compressive loads up to 14,137 N, with negligible off axis loading, achieving target stresses of 500 MPa for samples of up to 6.00 mm in diameter. The system will be used in the future to study the structural changes in ceramics and ceramic composites, as well as to study thermal residual stress redistribution under applied compressive loads. A broad variety of Raman active ceramics, including the traditional structural ceramics 3mol%Y2O3-ZrO2, B4C, SiC, Si3N4, as well as exotic materials such as LaCoO3 and other perovskites will be studied using this system. Calibration of the systems load cell was performed in the configured state using MTS universal testing machines. To ensure residual stresses from mounting the load cell did not invalidate the original calibration, the in-situ compression stage was tested once attached to the Renishaw Raman spectrometer using LaCoO3 ceramic samples. The Raman shift of certain peaks in LaCoO3 was detected indicative of the effect of the applied compressive stress on the ceramics understudy.
Show less - Date Issued
- 2019
- Identifier
- CFE0007824, ucf:52809
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007824
- Title
- The Impact of Elementary Mathematics Workshops on Mathematics Knowledge for Parenting (MKP) and Beliefs About Learning Mathematics.
- Creator
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Eisenreich, Heidi, Dixon, Juli, Ortiz, Enrique, Andreasen, Janet, Brooks, Lisa, Hahs-Vaughn, Debbie, University of Central Florida
- Abstract / Description
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The purpose of this study was to investigate the extent to which parents of first, second, and third grade students who attended a two-day workshop on mathematics strategies differed on average and over time, as compared to parents who did not attend the workshops. The following areas were measured: mathematics content knowledge, beliefs about learning mathematics, ability to identify correct student responses regarding mathematics, ability to identify student errors in solving mathematics...
Show moreThe purpose of this study was to investigate the extent to which parents of first, second, and third grade students who attended a two-day workshop on mathematics strategies differed on average and over time, as compared to parents who did not attend the workshops. The following areas were measured: mathematics content knowledge, beliefs about learning mathematics, ability to identify correct student responses regarding mathematics, ability to identify student errors in solving mathematics problems, methods used to solve problems, and comfort level with manipulatives.
Show less - Date Issued
- 2016
- Identifier
- CFE0006101, ucf:52877
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006101
- Title
- CLAIMS OF MISTAKEN IDENTITY:AN EXAMINATION OF U.S. TELEVISION FOOD COMMERCIALS AND THE ADULT OBESITY ISSUE.
- Creator
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Delgado, Cristina, DeLorme, Denise, University of Central Florida
- Abstract / Description
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Obesity is one of the major public health issues in the United States, often regarded as part of a global crisis. Companies invest billions of dollars each year towards television advertising campaigns aimed at convincing audiences how their ground-breaking discovery 'battles the bulge' or somehow offers an increased health benefit. This study examined how advertisers presented health-related claims, including health and nutrient-content claims, in U.S. adult-targeted television food...
Show moreObesity is one of the major public health issues in the United States, often regarded as part of a global crisis. Companies invest billions of dollars each year towards television advertising campaigns aimed at convincing audiences how their ground-breaking discovery 'battles the bulge' or somehow offers an increased health benefit. This study examined how advertisers presented health-related claims, including health and nutrient-content claims, in U.S. adult-targeted television food commercials. The claims were compared to FTC, FDA, and USDA laws, regulations, and recommendations. A content analysis of food advertising was conducted of commercials from major and cable network programs broadcast during prime-time in the first quarter of 2009. The majority of claims match current regulations when compared to Federal references. The results show that Nutrient and Wellness claims were the most frequently cited. The type of benefit, Healthy Eating, emerged almost 3 times more than any other benefit type. This is also similar to those results which suggest advertisers' intentions were to promote overall wellness in their content delivery. As such, the Wellness Approach was identified and conceptualized, leading towards full development of a Wellness Effect theory. Implications and future research opportunities are discussed on both a theoretical and practical level.
Show less - Date Issued
- 2009
- Identifier
- CFE0002565, ucf:48260
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002565
- Title
- Settlement History and Interaction in the Manialtepec Basin of Oaxaca's Central Coast.
- Creator
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Menchaca, Victoria, Barber, Sarah, Walker, John, Chase, Arlen, University of Central Florida
- Abstract / Description
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As the focus of over 70 years' of archaeological research, Oaxaca, Mexico, is one of Mesoamerica's best understood regions. Yet, despite the volume of work in Oaxaca, information about one of its key resource areas, the central Pacific coast, remains limited. Specifically, the ambiguous role of Oaxaca's Central Coast in interregional relationships during pre-Hispanic times to the sites of Monte Alb(&)#225;n and Tututepec has been a chronic problem and major source of debate for decades. The...
Show moreAs the focus of over 70 years' of archaeological research, Oaxaca, Mexico, is one of Mesoamerica's best understood regions. Yet, despite the volume of work in Oaxaca, information about one of its key resource areas, the central Pacific coast, remains limited. Specifically, the ambiguous role of Oaxaca's Central Coast in interregional relationships during pre-Hispanic times to the sites of Monte Alb(&)#225;n and Tututepec has been a chronic problem and major source of debate for decades. The purpose of this thesis is to begin clarifying the role of Oaxaca's Central Coast in interregional networks and its pre-Hispanic history. Analysis utilized surface observations, surface collections, and information from limited excavations performed by the Proyecto Arqueol(&)#243;gico Laguna de Manialtepec (PALM) in the Manialtepec Basin, located on the Central Coast of Oaxaca. The data was then mapped using ArcGIS software to render settlement and artifact patterns. Based on the results of this project I suggest a history of settlement for this area. I also argue that the Basin contained three centers, maintained interregional interactions, and was invaded by the Mixtecs of highland Oaxaca during the Late Postclassic Period (A.D. 1200-1500).
Show less - Date Issued
- 2015
- Identifier
- CFE0005843, ucf:50920
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005843
- Title
- Textbook Cost-Lowering Initiatives: An Exploration of Community College Faculty Experiences.
- Creator
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Dunn, Susan, Cintron Delgado, Rosa, Owens, James, Boyd, Tammy, Mcardle, Michele, University of Central Florida
- Abstract / Description
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Faculty have been identified as critical players in the implementation of textbook affordability efforts at community colleges. Furthermore, emerging lower-cost alternatives to traditional textbooks present a wide and growing range of options that may help further efforts. This study sought to examine more closely the role of faculty with respect to textbook cost-lowering initiatives. The researcher utilized in-depth interviews to gain a rich picture of the experiences, attitudes, beliefs,...
Show moreFaculty have been identified as critical players in the implementation of textbook affordability efforts at community colleges. Furthermore, emerging lower-cost alternatives to traditional textbooks present a wide and growing range of options that may help further efforts. This study sought to examine more closely the role of faculty with respect to textbook cost-lowering initiatives. The researcher utilized in-depth interviews to gain a rich picture of the experiences, attitudes, beliefs, and behaviors of nine full-time community college faculty as they confronted textbook affordability efforts and textbook alternatives. The interview data were analyzed using a thematic analysis process. Five major themes and three minor themes were identified. The five major themes were: (a) campus administrators support, but do not mandate, efforts; (b) frequent edition revisions frustrate faculty; (c) departmental approaches to textbook selection vary; (d) content, then affordability, drive selection choices; and (e) faculty have mixed feelings about textbook alternatives. The three minor themes were: (a) faculty efforts to save students money are thwarted by campus bookstores and financial aid policies; (b) English faculty benefit from public domain readings; and (c) more faculty participating in textbook selection means more difficulty deciding on a text. Implications and recommendations were offered for community college leaders, campus bookstores, publishers, and future researchers.
Show less - Date Issued
- 2014
- Identifier
- CFE0005159, ucf:50715
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005159
- Title
- University Students' Citizenship Shaped by Service-Learning, Community Service, and Peer-to-Peer Civic Discussions.
- Creator
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Winston, Haley, Cintron Delgado, Rosa, Welch, Kerry, Malaret, Stacey, Bowdon, Melody, University of Central Florida
- Abstract / Description
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Citizenship is often referred to as the forgotten outcome of colleges and universities. The present study examined the relationship between undergraduate students' perceived citizenship level and different types of civic experiences (service-learning, community service, and peer-to-peer civic discussions) and also different demographic factors (gender, race/ethnicity, and parental level of education) at a public institution using the Personal and Social Responsibility Inventory. This study...
Show moreCitizenship is often referred to as the forgotten outcome of colleges and universities. The present study examined the relationship between undergraduate students' perceived citizenship level and different types of civic experiences (service-learning, community service, and peer-to-peer civic discussions) and also different demographic factors (gender, race/ethnicity, and parental level of education) at a public institution using the Personal and Social Responsibility Inventory. This study used structural equation modeling and multiple regression analysis. This marks the first time these variables have been researched together. This study found a significant correlation between both community service and peer-to-peer civic discussions in relation to citizenship level. Yet, service-learning frequency was not found to be a significant factor. On the other hand, all three civic experiences together was found to be significantly correlated to citizenship aptitudes. Leading the researcher to find that a holistic (both inside and outside the classroom) approach to student citizenship is valuable for student development. Also, only one significant relationship was found between citizenship levels and any demographic variable (parental education level of doctorate or professional degree).
Show less - Date Issued
- 2017
- Identifier
- CFE0006927, ucf:51695
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006927
- Title
- Factors Affecting Systems Engineering Rigor in Launch Vehicle Organizations.
- Creator
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Gibson, Denton, Karwowski, Waldemar, Rabelo, Luis, Kotnour, Timothy, Kern, David, University of Central Florida
- Abstract / Description
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Systems engineering is a methodical multi-disciplinary approach to design, build, and operate complex systems. Launch vehicles are considered by many extremely complex systems that have greatly impacted where the systems engineering industry is today. Launch vehicles are used to transport payloads from the ground to a location in space. Satellites launched by launch vehicles can range from commercial communications to national security payloads. Satellite costs can range from a few million...
Show moreSystems engineering is a methodical multi-disciplinary approach to design, build, and operate complex systems. Launch vehicles are considered by many extremely complex systems that have greatly impacted where the systems engineering industry is today. Launch vehicles are used to transport payloads from the ground to a location in space. Satellites launched by launch vehicles can range from commercial communications to national security payloads. Satellite costs can range from a few million dollars to billions of dollars. Prior research suggests that lack of systems engineering rigor as one of the leading contributors to launch vehicle failures. A launch vehicle failure could have economic, societal, scientific, and national security impacts. This is why it is critical to understand the factors that affect systems engineering rigor in U.S. launch vehicle organizations.The current research examined organizational factors that influence systems engineering rigor in launch vehicle organizations. This study examined the effects of the factors of systems engineering culture and systems engineering support on systems engineering rigor. Particularly, the effects of top management support, organizational commitment, systems engineering support, and value of systems engineering were examined. This research study also analyzed the mediating role of systems engineering support between top management support and systems engineering rigor, as well as between organizational commitment and systems engineering rigor. A quantitative approach was used for this. Data for the study was collected via survey instrument. A total of 203 people in various systems engineering roles in launch vehicle organizations throughout the United States voluntarily participated. Each latent construct of the study was validated using confirmatory factor analysis (CFA). Structural equation modeling (SEM) was used to examine the relationships between the variables of the study. The IBM SPSS Amos 25 software was used to analyze the CFA and SEM.
Show less - Date Issued
- 2019
- Identifier
- CFE0007806, ucf:52348
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007806
- Title
- THE RELATIONSHIP BETWEEN GENRE CHOICE OF MUSIC AND ALTRUISTIC BEHAVIOR.
- Creator
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Hippler, Christine, Whitten, Shannon, University of Central Florida
- Abstract / Description
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ABSTRACT Extensive research has documented the relationship between listening to certain genres of music and negative effects on social behavior such as aggressive and antisocial behavior. The present study explored whether there are genres of music associated with altruism. Altruistic behavior is defined as behavior that is consistently more caring, helpful, considerate of other's feelings, and self- sacrificing. These behaviors promote our ability to thrive as a community. Yet, few studies...
Show moreABSTRACT Extensive research has documented the relationship between listening to certain genres of music and negative effects on social behavior such as aggressive and antisocial behavior. The present study explored whether there are genres of music associated with altruism. Altruistic behavior is defined as behavior that is consistently more caring, helpful, considerate of other's feelings, and self- sacrificing. These behaviors promote our ability to thrive as a community. Yet, few studies have addressed the relationship between music and altruism. Data was collected from 608 college students who completed a self-report altruism scale, music preference measure, the Marlowe Crowne social desirability scale, and a demographic information form in order to see if there is a relationship between choice of music and altruism. A multiple hierarchal regression analysis found music genre choice accounted for 15.9 percent of variance in self-reported altruism. Significant, positive correlations emerged also between altruism and several music genres including alternative, country, classical, and emo.
Show less - Date Issued
- 2011
- Identifier
- CFH0003820, ucf:44753
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0003820
- Title
- Adaptive Architectural Strategies for Resilient Energy-Aware Computing.
- Creator
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Ashraf, Rizwan, DeMara, Ronald, Lin, Mingjie, Wang, Jun, Jha, Sumit, Johnson, Mark, University of Central Florida
- Abstract / Description
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Reconfigurable logic or Field-Programmable Gate Array (FPGA) devices have the ability to dynamically adapt the computational circuit based on user-specified or operating-condition requirements. Such hardware platforms are utilized in this dissertation to develop adaptive techniques for achieving reliable and sustainable operation while autonomously meeting these requirements. In particular, the properties of resource uniformity and in-field reconfiguration via on-chip processors are exploited...
Show moreReconfigurable logic or Field-Programmable Gate Array (FPGA) devices have the ability to dynamically adapt the computational circuit based on user-specified or operating-condition requirements. Such hardware platforms are utilized in this dissertation to develop adaptive techniques for achieving reliable and sustainable operation while autonomously meeting these requirements. In particular, the properties of resource uniformity and in-field reconfiguration via on-chip processors are exploited to implement Evolvable Hardware (EHW). EHW utilize genetic algorithms to realize logic circuits at runtime, as directed by the objective function. However, the size of problems solved using EHW as compared with traditional approaches has been limited to relatively compact circuits. This is due to the increase in complexity of the genetic algorithm with increase in circuit size. To address this research challenge of scalability, the Netlist-Driven Evolutionary Refurbishment (NDER) technique was designed and implemented herein to enable on-the-fly permanent fault mitigation in FPGA circuits. NDER has been shown to achieve refurbishment of relatively large sized benchmark circuits as compared to related works. Additionally, Design Diversity (DD) techniques which are used to aid such evolutionary refurbishment techniques are also proposed and the efficacy of various DD techniques is quantified and evaluated.Similarly, there exists a growing need for adaptable logic datapaths in custom-designed nanometer-scale ICs, for ensuring operational reliability in the presence of Process, Voltage, and Temperature (PVT) and, transistor-aging variations owing to decreased feature sizes for electronic devices. Without such adaptability, excessive design guardbands are required to maintain the desired integration and performance levels. To address these challenges, the circuit-level technique of Self-Recovery Enabled Logic (SREL) was designed herein. At design-time, vulnerable portions of the circuit identified using conventional Electronic Design Automation tools are replicated to provide post-fabrication adaptability via intelligent techniques. In-situ timing sensors are utilized in a feedback loop to activate suitable datapaths based on current conditions that optimize performance and energy consumption. Primarily, SREL is able to mitigate the timing degradations caused due to transistor aging effects in sub-micron devices by reducing the stress induced on active elements by utilizing power-gating. As a result, fewer guardbands need to be included to achieve comparable performance levels which leads to considerable energy savings over the operational lifetime.The need for energy-efficient operation in current computing systems has given rise to Near-Threshold Computing as opposed to the conventional approach of operating devices at nominal voltage. In particular, the goal of exascale computing initiative in High Performance Computing (HPC) is to achieve 1 EFLOPS under the power budget of 20MW. However, it comes at the cost of increased reliability concerns, such as the increase in performance variations and soft errors. This has given rise to increased resiliency requirements for HPC applications in terms of ensuring functionality within given error thresholds while operating at lower voltages. My dissertation research devised techniques and tools to quantify the effects of radiation-induced transient faults in distributed applications on large-scale systems. A combination of compiler-level code transformation and instrumentation are employed for runtime monitoring to assess the speed and depth of application state corruption as a result of fault injection. Finally, fault propagation models are derived for each HPC application that can be used to estimate the number of corrupted memory locations at runtime. Additionally, the tradeoffs between performance and vulnerability and the causal relations between compiler optimization and application vulnerability are investigated.
Show less - Date Issued
- 2015
- Identifier
- CFE0006206, ucf:52889
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006206
