Current Search: Power (x)
Pages
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Title
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HIGH TEMPERATURE PACKAGING FOR WIDE BANDGAP SEMICONDUCTOR DEVICES.
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Creator
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Grummel, Brian, Shen, Z. John, University of Central Florida
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Abstract / Description
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Currently, wide bandgap semiconductor devices feature increased efficiency, higher current handling capabilities, and higher reverse blocking voltages than silicon devices while recent fabrication advances have them drawing near to the marketplace. However these new semiconductors are in need of new packaging that will allow for their application in several important uses including hybrid electrical vehicles, new and existing energy sources, and increased efficiency in multiple new and...
Show moreCurrently, wide bandgap semiconductor devices feature increased efficiency, higher current handling capabilities, and higher reverse blocking voltages than silicon devices while recent fabrication advances have them drawing near to the marketplace. However these new semiconductors are in need of new packaging that will allow for their application in several important uses including hybrid electrical vehicles, new and existing energy sources, and increased efficiency in multiple new and existing technologies. Also, current power module designs for silicon devices are rife with problems that must be enhanced to improve reliability. This thesis introduces new packaging that is thermally resilient and has reduced mechanical stress from temperature rise that also provides increased circuit lifetime and greater reliability for continued use to 300°C which is within operation ratings of these new semiconductors. The new module is also without problematic wirebonds that lead to a majority of traditional module failures which also introduce parasitic inductance and increase thermal resistance. Resultantly, the module also features a severely reduced form factor in mass and volume.
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Date Issued
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2008
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Identifier
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CFE0002482, ucf:47690
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0002482
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Title
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HIGH SPEED TURBO TCM OFDM FOR UWB AND POWERLINE SYSTEM.
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Creator
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WANG, YANXIA, Wei, Lei, University of Central Florida
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Abstract / Description
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Turbo Trellis-Coded Modulation (TTCM) is an attractive scheme for higher data rate transmission, since it combines the impressive near Shannon limit error correcting ability of turbo codes with the high spectral efficiency property of TCM codes. We build a punctured parity-concatenated trellis codes in which a TCM code is used as the inner code and a simple parity-check code is used as the outer code. It can be constructed by simple repetition, interleavers, and TCM and functions as standard...
Show moreTurbo Trellis-Coded Modulation (TTCM) is an attractive scheme for higher data rate transmission, since it combines the impressive near Shannon limit error correcting ability of turbo codes with the high spectral efficiency property of TCM codes. We build a punctured parity-concatenated trellis codes in which a TCM code is used as the inner code and a simple parity-check code is used as the outer code. It can be constructed by simple repetition, interleavers, and TCM and functions as standard TTCM but with much lower complexity regarding real world implementation. An iterative bit MAP decoding algorithm is associated with the coding scheme. Orthogonal Frequency Division Multiplexing (OFDM) modulation has been a promising solution for efficiently capturing multipath energy in highly dispersive channels and delivering high data rate transmission. One of UWB proposals in IEEE P802.15 WPAN project is to use multi-band OFDM system and punctured convolutional codes for UWB channels supporting data rate up to 480Mb/s. The HomePlug Networking system using the medium of power line wiring also selects OFDM as the modulation scheme due to its inherent adaptability in the presence of frequency selective channels, its resilience to jammer signals, and its robustness to impulsive noise in power line channel. The main idea behind OFDM is to split the transmitted data sequence into N parallel sequences of symbols and transmit on different frequencies. This structure has the particularity to enable a simple equalization scheme and to resist to multipath propagation channel. However, some carriers can be strongly attenuated. It is then necessary to incorporate a powerful channel encoder, combined with frequency and time interleaving. We examine the possibility of improving the proposed OFDM system over UWB channel and HomePlug powerline channel by using our Turbo TCM with QAM constellation for higher data rate transmission. The study shows that the system can offer much higher spectral efficiency, for example, 1.2 Gbps for OFDM/UWB which is 2.5 times higher than the current standard, and 39 Mbps for OFDM/HomePlug1.0 which is 3 times higher than current standard. We show several essential requirements to achieve high rate such as frequency and time diversifications, multi-level error protection. Results have been confirmed by density evolution. The effect of impulsive noise on TTCM coded OFDM system is also evaluated. A modified iterative bit MAP decoder is provided for channels with impulsive noise with different impulsivity.
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Date Issued
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2006
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Identifier
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CFE0000943, ucf:46745
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000943
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Title
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EYES IN THE TEXT: SURVEYING THE OCULAR AESTHETIC IN PAT BARKER'S WAR TRILOGY.
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Creator
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Hammond, James, Campbell, James, University of Central Florida
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Abstract / Description
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ABSTRACT In 1991, British novelist Patricia Barker published Regeneration, the first of three novels that portrayed the exploits of both factual and fictional characters during the darkest days of WWI. Barker's Eye in the Door (1993), followed by The Ghost Road (1995) for which she won the Booker Prize for Fiction, completed the series that explored the effects of combat on the human psyche. What emerges as a dominant feature of Barker's war novels is her depiction of the ocular sense....
Show moreABSTRACT In 1991, British novelist Patricia Barker published Regeneration, the first of three novels that portrayed the exploits of both factual and fictional characters during the darkest days of WWI. Barker's Eye in the Door (1993), followed by The Ghost Road (1995) for which she won the Booker Prize for Fiction, completed the series that explored the effects of combat on the human psyche. What emerges as a dominant feature of Barker's war novels is her depiction of the ocular sense. Reminiscent of Orwellianism, Barker's texts contain a seemingly ubiquitous ocular presence. For example, neurasthenic patients are scrutinized by army psychiatrists, objectors and subversives are spied upon or imprisoned so that their activities may be observed, and combatants are faced with the challenge of reconciling the horrifying events they have witnessed in combat. This study investigates the role and importance of Pat Barker's depiction of eyes and visuality in her war trilogy. The overreaching goal of the thesis to examine Barker's aestheticized notion of ocularity. It is my aim to come some conclusions about how vision / ocularity signal the emergence of a few central themes in the texts such as power relationships, objectification, exposure and the transgression of boundaries. The social and linguistic theories of Michael Foucault, Roland Barthes, Georges Bataille, Martin Jay and others who have addressed the themes of perception and ocular symbolism will be introduced into my discussion with the aim of providing a theoretic foundation to many of my assertions. Chapters will begin with an interpretation of a piece of theoretical writing by one of these authors followed by an analysis of Barker's texts that incorporates the major tenets of that theory. These tenets will serve as a basis to my discussion and it is my hope that, through the creative application of theoretical writing, I will address a number of aspects of Barker's work, especially in relation to her ocular imagery, that that have thus far gone unexplored.
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Date Issued
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2005
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Identifier
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CFE0000832, ucf:46681
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000832
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Title
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IRGC AND IRANIAN SOFT AND HARD POWER INFLUENCE WITHIN THE MIDDLE EAST.
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Creator
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Urbina, Daryl F, Sadri, Houman A., University of Central Florida
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Abstract / Description
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The IRGC, or the Iranian Revolutionary Guard Corps, and Iran have utilized soft power to increase their influence within the Middle East. By using military superiority; ideological influence; and trade, both the Iran and the IRGC established dependency between themselves and patron states. Of these patron states, the research focuses on Iraq; Syria; and Yemen, and how Iran and the IRGC affect them through soft power. This research suggests that Iran and the IRGC is using the disability of the...
Show moreThe IRGC, or the Iranian Revolutionary Guard Corps, and Iran have utilized soft power to increase their influence within the Middle East. By using military superiority; ideological influence; and trade, both the Iran and the IRGC established dependency between themselves and patron states. Of these patron states, the research focuses on Iraq; Syria; and Yemen, and how Iran and the IRGC affect them through soft power. This research suggests that Iran and the IRGC is using the disability of the aforementioned states to increase their own influence by making them dependent on Iranian military supplies; cultural indoctrination to align with Iranian ideology; and economic dependent on Iran. As Iran's influence grows within these states, its power in the Middle East grows and becomes a security risk for Saudi Arabia; Israel; and any other regime that does not have its interests align with the Iranian regime.
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Date Issued
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2018
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Identifier
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CFH2000444, ucf:45770
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFH2000444
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Title
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CRACK MOTHERS, CRACK BABIES, AND BLACK MALE DOPE DEALERS: PRODUCTIONS OF DEVIANCE DURING AMERICA'S CRACK COCAINE PANIC IN THE 1980S.
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Creator
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Yandow, Chantelle, Schippert, Claudia, University of Central Florida
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Abstract / Description
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A moral panic erupted during the 1980s among the American public when stories about crack cocaine saturated the media. In this thesis I analyze how discursive productions of deviancy operated in the CBS news documentary: 48 Hours on Crack Street (1986) and other print news sources at that time. Three salient characters that appear in news media discourse during the panic are "crack mothers," "crack babies," and "Black male dope dealers." The news media frightened the public with such...
Show moreA moral panic erupted during the 1980s among the American public when stories about crack cocaine saturated the media. In this thesis I analyze how discursive productions of deviancy operated in the CBS news documentary: 48 Hours on Crack Street (1986) and other print news sources at that time. Three salient characters that appear in news media discourse during the panic are "crack mothers," "crack babies," and "Black male dope dealers." The news media frightened the public with such representations (among others) and the public urged politicians to get tough on drug crime to control the so-called crack cocaine plague. Politicians responded with omnibus drug reforms that established mandatory minimum sentences and the controversial 100:1 sentencing disparity between crack and powder cocaine. The enforcement of the draconian drug laws that were passed in response to the crack cocaine panic continues to be a contributing factor to America's current prison crisis. Moreover, the laws are enforced in ways that disproportionately punish the poor and African-Americans. I conclude that the criminal disenfranchisement of millions of people since the 1980s relates to the media's representation of the crack cocaine "epidemic" and the legislation that was passed to control illicit drugs such as crack cocaine.
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Date Issued
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2011
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Identifier
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CFH0003822, ucf:44758
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFH0003822
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Title
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EMBEDDED MAGNETICS FOR POWER SYSTEM ON CHIP (PSOC).
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Creator
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Lu, Jian, Shen, Z. John, University of Central Florida
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Abstract / Description
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A novel concept of on-chip bondwire inductors and transformers with ferrite epoxy glob coating is proposed, offering a cost effective approach to realize power systems on chip (PSoC) or System-in-Package (PSiP). The concept has been investigated both experimentally and with finite element modeling. Improvement in total inductance is demonstrated for multi-turn bondwire inductors over single bondwire inductors. The inductance and Q factor can be further boosted with coupled multi-turn inductor...
Show moreA novel concept of on-chip bondwire inductors and transformers with ferrite epoxy glob coating is proposed, offering a cost effective approach to realize power systems on chip (PSoC) or System-in-Package (PSiP). The concept has been investigated both experimentally and with finite element modeling. Improvement in total inductance is demonstrated for multi-turn bondwire inductors over single bondwire inductors. The inductance and Q factor can be further boosted with coupled multi-turn inductor concept. Transformer parameters including self- and mutual inductance, and coupling factors are extracted from both modeled and measured S-parameters. More importantly, the bondwire magnetic components can be easily integrated into SoC manufacturing processes with minimal changes to the layout, and open enormous possibilities for realizing cost-effective, high current, high efficiency PSoC's or PSiP's. The design guidelines for single bondwire inductors as well as multi-turn inductors are discussed step by step in several chapters. Not only is the innovated concept for bondwire inductor with ferrite ink presented, but also the practical implementation and design rules are given. With all the well defined steps, people who want to use these bondwire inductors with ferrite ink in their PSoC research or products will find it as simple as using commercial inductors. Last but not least, the PSoC concept using a bondwire inductor is demonstrated by building the prototype of dc-dc buck converter IC as well as the whole package. IC and the whole function block are tested and presented in this work.
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Date Issued
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2009
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Identifier
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CFE0002952, ucf:47953
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0002952
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Title
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Single Mode Wavelength-Tunable Thulium Fiber.
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Creator
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Shin, Dong Jin, Richardson, Martin, Schulzgen, Axel, Amezcua Correa, Rodrigo, University of Central Florida
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Abstract / Description
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Thulium fiber lasers have the broadest emission wavelength bandwidth out of any rare-earth doped fiber lasers. The emission wavelength starts from 1.75(&)#181;m and ends at around 2.15(&)#181;m, covering a vast swath of the eye safe wavelength region and intersecting with a large portion of mid-infrared atmospheric transmission window. Also, thulium fiber lasers provide the highest average output power of any other rare-earth doped fiber lasers in these wavelength regimes, making them...
Show moreThulium fiber lasers have the broadest emission wavelength bandwidth out of any rare-earth doped fiber lasers. The emission wavelength starts from 1.75(&)#181;m and ends at around 2.15(&)#181;m, covering a vast swath of the eye safe wavelength region and intersecting with a large portion of mid-infrared atmospheric transmission window. Also, thulium fiber lasers provide the highest average output power of any other rare-earth doped fiber lasers in these wavelength regimes, making them uniquely suited for applications such as remote sensing. At the moment, high power beam propagation of continuous wave laser through the atmosphere in the mid-infrared range is yet to be investigated anywhere. In particular, the effects of atmospheric water vapors on the thulium fiber laser propagation are unknown and are of great research interest. This dissertation identifies the stringent requirements in constructing a high power, single frequency, wavelength tunable, continuous wave thulium fiber laser with the aim of using it to study various atmospheric transmission effects. A fine spectral control scheme using diffraction gratings is explored and improvements are made. Moreover, a fiber numerical simulation model is presented and is used for designing and implementing the thulium fiber laser system. The current limitations of the implemented system are discussed and an improved system is proposed. This will lay the foundation for the future high power atmospheric propagation studies.
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Date Issued
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2018
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Identifier
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CFE0007372, ucf:52084
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007372
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Title
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Development of an Adaptive Restoration Tool For a Self-Healing Smart Grid.
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Creator
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Golshani, Amir, Sun, Wei, Qu, Zhihua, Vosoughi, Azadeh, Zhou, Qun, Zheng, Qipeng, University of Central Florida
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Abstract / Description
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Large power outages become more commonplace due to the increase in both frequency and strength of natural disasters and cyber-attacks. The outages and blackouts cost American industries and business billions of dollars and jeopardize the lives of hospital patients. The losses can be greatlyreduced with a fast, reliable and flexible restoration tool. Fast recovery and successfully adapting to extreme events are critical to build a resilient, and ultimately self-healing power grid. This...
Show moreLarge power outages become more commonplace due to the increase in both frequency and strength of natural disasters and cyber-attacks. The outages and blackouts cost American industries and business billions of dollars and jeopardize the lives of hospital patients. The losses can be greatlyreduced with a fast, reliable and flexible restoration tool. Fast recovery and successfully adapting to extreme events are critical to build a resilient, and ultimately self-healing power grid. This dissertation is aimed to tackle the challenging task of developing an adaptive restoration decisionsupport system (RDSS). The RDSS determines restoration actions both in planning and real-time phases and adapts to constantly changing system conditions. First, an efficient network partitioning approach is developed to provide initial conditions for RDSS by dividing large outage network into smaller islands. Then, the comprehensive formulation of RDSS integrates different recovery phases into one optimization problem, and encompasses practical constraints including AC powerflow, dynamic reserve, and dynamic behaviors of generators and load. Also, a frequency constrained load recovery module is proposed and integrated into the RDSS to determine the optimal location and amount of load pickup. Next, the proposed RDSS is applied to harness renewable energy sources and pumped-storage hydro (PSH) units by addressing the inherent variabilities and uncertainties of renewable and coordinating wind and PSH generators. A two-stage stochastic and robust optimization problem is formulated, and solved by the integer L-shaped and column-and-constraintsgeneration decomposition algorithms. The developed RDSS tool has been tested onthe modified IEEE 39-bus and IEEE 57-bus systems under different scenarios. Numerical results demonstrate the effectiveness and efficiency of the proposed RDSS. In case of contingencies or unexpected outages during the restoration process, RDSS can quickly update the restoration plan and adapt to changing system conditions. RDSS is an important step toward a self-healing power grid and its implementation will reduce the recovery time while maintaining system security.
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Date Issued
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2017
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Identifier
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CFE0007284, ucf:52169
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007284
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Title
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2 micron fiber lasers: power scaling concepts and limitations.
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Creator
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Sincore, Alex, Richardson, Martin, Amezcua Correa, Rodrigo, Schulzgen, Axel, Shah, Lawrence, University of Central Florida
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Abstract / Description
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Thulium- and holmium-doped fiber lasers (TDF and HDF) emitting at 2 micron offer unique benefits and applications compared to common ytterbium-doped 1 micron lasers. This dissertation details the concepts, limitations, design, and performance of four 2 micron fiber laser systems. While these lasers were developed for various end-uses, they also provide further insight into two major power scaling limitations. The first limitation is optical nonlinearities: specifically stimulated Brillouin...
Show moreThulium- and holmium-doped fiber lasers (TDF and HDF) emitting at 2 micron offer unique benefits and applications compared to common ytterbium-doped 1 micron lasers. This dissertation details the concepts, limitations, design, and performance of four 2 micron fiber laser systems. While these lasers were developed for various end-uses, they also provide further insight into two major power scaling limitations. The first limitation is optical nonlinearities: specifically stimulated Brillouin scattering (SBS) and modulation instability (MI). The second limitation is thermal failure due to inefficient pump conversion. First, a 21.5 W single-frequency, single-mode laser with adjustable output from continuous-wave to nanosecond pulses is developed. Measuring the SBS threshold versus pulse duration enables the Brillouin gain coefficient and gain bandwidth to be determined at 2 micron. Second, a 23 W spectrally-broadband, nanosecond pulsed laser is constructed for materials processing applications. The temporally incoherent multi-kW peak power pulses can also efficiently produce MI and supercontinuum generation by adjusting the input spectral linewidth. Third, the measured performance of in-band pumped TDF and HDF lasers are compared with simulations. HDF displays low efficiencies, which is explained by including ion clustering in the simulations. The TDF operates with impressive (>)90% slope efficiencies. Based on this result, a system design for (>)1 kW average power TDF amplifier is described. The designed final amplifier will be in-band pumped to enable high efficiency and low thermal load. The amplifier efficiency, operating bandwidth, thermal load, and nonlinear limits are modeled and analyzed to provide a framework for execution. Overall, this dissertation provides further insight and understanding on the various processes that limit power scaling of 2 micron fiber lasers.
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Date Issued
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2018
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Identifier
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CFE0007374, ucf:52105
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007374
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Title
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Energy aware design and analysis for synchronous and asynchronous circuits.
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Creator
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Di, Jia, Yuan, Jiann S., Engineering and Computer Science
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Abstract / Description
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University of Central Florida College of Engineering Thesis; Power dissipation has become a major concern for IC designers. Various low power design techniques have been developed for synchronous circuits. Asynchronous circuits, however have gained more interests recently due to their benefits in lower noise, easy timing control, etc. But few publications on energy reduction techniques for asynchronous logic are available. Power awareness indicates the ability of the system power to scale...
Show moreUniversity of Central Florida College of Engineering Thesis; Power dissipation has become a major concern for IC designers. Various low power design techniques have been developed for synchronous circuits. Asynchronous circuits, however have gained more interests recently due to their benefits in lower noise, easy timing control, etc. But few publications on energy reduction techniques for asynchronous logic are available. Power awareness indicates the ability of the system power to scale with changing conditions and quality requirements. Scalability is an important figure-of-merit since it allows the end user to implement operational policy just like the user of mobile multimedia equipment needs to select between better quality and longer battery operation time. This dissertation discusses power /energy optimization and performs analysis on both synchronous and asynchronous logic.
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Date Issued
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2004
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Identifier
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CFR0001720, ucf:52913
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFR0001720
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Title
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THE PAY EQUITY DILEMMA WOMEN FACE AROUND THE WORLD.
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Creator
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McMurray, Lana D, Yayla-Kullu, Muge, University of Central Florida
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Abstract / Description
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In this research, I examine the pay equity dilemma women face around the world and how it is different in various regions of the world. My research question focuses on "how a nation's cultural characteristics affect pay equity?" It is already documented that men are paid more than women. The goal of this study is to explain how individual characteristics of national culture (such as masculinity, individualism, power distance, and uncertainty avoidance) impacts this inequality. By increasing...
Show moreIn this research, I examine the pay equity dilemma women face around the world and how it is different in various regions of the world. My research question focuses on "how a nation's cultural characteristics affect pay equity?" It is already documented that men are paid more than women. The goal of this study is to explain how individual characteristics of national culture (such as masculinity, individualism, power distance, and uncertainty avoidance) impacts this inequality. By increasing the understanding of pay inequality, changes can be made that will improve the lives of not just women but the families of those women and the world overall. We use data from Geert Hofstede's national culture dimensions and the Global Gender Gap Report by the World Economic Forum. Our results suggest that gender gap reduces in low power distance cultures, in high individualistic cultures, in low masculine cultures, and in low uncertainty avoidance cultures. Our results provide evidence that the economic prosperity of women around the world is significantly impacted by cultural dimensions.
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Date Issued
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2018
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Identifier
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CFH2000372, ucf:52906
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFH2000372
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Title
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Performing Bernarda: Activating Power and Identity.
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Creator
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Martinez Medina, Ana, Ingram, Kate, Listengarten, Julia, StClaire, Sybil, University of Central Florida
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Abstract / Description
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The musical Bernarda Alba tells the story of a woman who is confined within the heavily patriarchal and Catholic society that was 1930s Spain. Because of this, I thought it the perfect arena to explore power dynamics on stage. My thesis will explore status, hierarchies, relationships, and identity via the stolid matriarchal character Bernarda Alba. Through analyzing the playwright's words, fleshing out the character, and exploring the character's relationships with others in rehearsal, I have...
Show moreThe musical Bernarda Alba tells the story of a woman who is confined within the heavily patriarchal and Catholic society that was 1930s Spain. Because of this, I thought it the perfect arena to explore power dynamics on stage. My thesis will explore status, hierarchies, relationships, and identity via the stolid matriarchal character Bernarda Alba. Through analyzing the playwright's words, fleshing out the character, and exploring the character's relationships with others in rehearsal, I have studied how to activate status on stage. There are many sociology theories and psychological studies that can be applied to theatre-making in order to create fleshed out relationships, characters, and worlds. I have taken these theories into practice, as I battled with my own hierarchies in real life, and I let art and life do what they do best: imitate each other. I will analyze and play with the physical movement and posture of the character, the vocal choices in the delivery of the scripted words, and the psychological choices in the form of subtext and unspoken thought. There is an abundance of agency one holds when creating status and identity for a character, and I break down the different facets to explore. More importantly, outside of the stage, if we realize that status is more intricate and flexible than we think it is, then we as individuals can unlock invaluable freedoms that can unchain us from daily oppression.
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Date Issued
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2019
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Identifier
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CFE0007498, ucf:52655
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007498
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Title
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I'm Not Your Waifu: Sexual Harassment and Assault in Cosplay, Anime (&) Comic Conventions.
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Creator
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Ellsworth, Alexandria, Huff-Corzine, Lin, Anthony, Amanda, Reckdenwald, Amy, University of Central Florida
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Abstract / Description
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Women face sexual harassment and sexual assault far too often with one in every six women sexually assaulted during their life (Tjaden (&) Thoennes, 1998). In the anime and comic community, women face sexual assault and harassment, often in open public spaces, due to these spaces being labeled as men's (Cote, 2015; Fox (&) Potocki 2015; Rodriguez 2015; Schott (&) Horrell 2000). Policies such as Cosplay is not Consent (Facebook, 2018) are not upheld or enforced by anime and comic conventions....
Show moreWomen face sexual harassment and sexual assault far too often with one in every six women sexually assaulted during their life (Tjaden (&) Thoennes, 1998). In the anime and comic community, women face sexual assault and harassment, often in open public spaces, due to these spaces being labeled as men's (Cote, 2015; Fox (&) Potocki 2015; Rodriguez 2015; Schott (&) Horrell 2000). Policies such as Cosplay is not Consent (Facebook, 2018) are not upheld or enforced by anime and comic conventions. Policies that are enforced, have clear and concise wording, and are enforced by staff and volunteers, who have been educated or trained to deal with sexual assault and harassment, may likely promote safer sexual assault and sexual harassment free anime and comic conventions. A total of 27 participants (20 women, 6 men, and 1 non-binary) were recruited via a snowball technique through Facebook social media groups. Participants were interviewed in-depth either face-to-face or through written interviews. The results showed that: (1) cosplay is a form of embodiment it does not negate the person's identity or bodily autonomy while wearing the cosplay; (2) women are generally the targets of sexual assault and harassment; (3) policies are often not enforced or enforced well due to lack of clear policies or consequences; (4) staff and volunteers are not educated, trained or equipped to deal with sexual assault and harassment; and 5) anime and comic convention organizers need to be responsible for helping to create safer environments for their attendees, staff, and volunteers.
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Date Issued
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2018
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Identifier
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CFE0007175, ucf:52281
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007175
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Title
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Constituting Rhetorical Agency in a Feminist Discursive Space.
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Creator
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Raynor, Ella, Scott, Blake, Jones, Natasha, Brenckle, Martha, University of Central Florida
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Abstract / Description
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This thesis details an analysis of a project called Exposing the Silence in order to learn about agency and discursive space. This gallery for traumatic birth stories serves as a relevant site for better understanding how women are constituting their experiences with embodied autonomy and rhetorical dis/empowerment and how they come together to visually and discursively form a feminist space online. I completed a rhetorical analysis of the birth narratives and of an interview with Lindsay...
Show moreThis thesis details an analysis of a project called Exposing the Silence in order to learn about agency and discursive space. This gallery for traumatic birth stories serves as a relevant site for better understanding how women are constituting their experiences with embodied autonomy and rhetorical dis/empowerment and how they come together to visually and discursively form a feminist space online. I completed a rhetorical analysis of the birth narratives and of an interview with Lindsay Askins, one of the creators of Exposing the Silence.My study finds that a dyadic relationship between embodied autonomy and rhetorical agency exists while women negotiate power constructs during their traumatic obstetric experiences. When their rhetorical agency was diminished, so was their embodied autonomy. While they asserted agency during the traumatic experience, loss of agency is the main reason for their feelings of trauma. However, they work to re-assert rhetorical agency by sharing their narratives in the discursive space. The discursive space of the website is feminist because it promotes the rhetorical agency of its users and provides the opportunity for its users to socially construct that agency.My study contributes to the rhetoric of health and medicine (RHM) through its focus on how women constitute their embodied autonomy and rhetorical agency when speaking about an experience in which they lost some amount of both. I especially contribute an interpretation of how rhetorical agency, a discursive assertion of agency, can interact with agency itself, or embodied autonomy, without being the same entities. This project also contributes to RHM through its focus on how an online feminist visual-discursive space is socially constructed by its occupants and creators to assert rhetorical agency.
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Date Issued
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2018
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Identifier
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CFE0007238, ucf:52238
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007238
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Title
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GaN Power Devices: Discerning Application-Specific Challenges and Limitations in HEMTs.
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Creator
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Binder, Andrew, Yuan, Jiann-Shiun, Sundaram, Kalpathy, Roy, Tania, Kapoor, Vikram, Chow, Lee, University of Central Florida
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Abstract / Description
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GaN power devices are typically used in the 600 V market, for high efficiency, high power-density systems. For these devices, the lateral optimization of gate-to-drain, gate, and gate-to-source lengths, as well as gate field-plate length are critical for optimizing breakdown voltage and performance. This work presents a systematic study of lateral scaling optimization for high voltage devices to minimize figure of merit and maximize breakdown voltage. In addition, this optimization is...
Show moreGaN power devices are typically used in the 600 V market, for high efficiency, high power-density systems. For these devices, the lateral optimization of gate-to-drain, gate, and gate-to-source lengths, as well as gate field-plate length are critical for optimizing breakdown voltage and performance. This work presents a systematic study of lateral scaling optimization for high voltage devices to minimize figure of merit and maximize breakdown voltage. In addition, this optimization is extended for low voltage devices ((<) 100 V), presenting results to optimize both lateral features and vertical features. For low voltage design, simulation work suggests that breakdown is more reliant on punch-through as the primary breakdown mechanism rather than on vertical leakage current as is the case with high-voltage devices. A fabrication process flow has been developed for fabricating Schottky-gate, and MIS-HEMT structures at UCF in the CREOL cleanroom. The fabricated devices were designed to validate the simulation work for low voltage GaN devices. The UCF fabrication process is done with a four layer mask, and consists of mesa isolation, ohmic recess etch, an optional gate insulator layer, ohmic metallization, and gate metallization. Following this work, the fabrication process was transferred to the National Nano Device Laboratories (NDL) in Hsinchu, Taiwan, to take advantage of the more advanced facilities there. Following fabrication, a study has been performed on defect induced performance degradation, leading to the observation of a new phenomenon: trap induced negative differential conductance (NDC). Typically NDC is caused by self-heating, however by implementing a substrate bias test in conjunction with pulsed I-V testing, the NDC seen in our fabricated devices has been confirmed to be from buffer traps that are a result of poor channel carrier confinement during the dc operating condition.
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Date Issued
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2019
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Identifier
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CFE0007885, ucf:52786
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0007885
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Title
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STUDY OF DESIGN FOR RELIABILITY OF RF AND ANALOG CIRCUITS.
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Creator
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Tang, Hongxia, Yuan, Jiann-Shiun, Wu, Xinzhang, Sundaram, Kalpathy, Chow, Lee, University of Central Florida
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Abstract / Description
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Due to continued device dimensions scaling, CMOS transistors in the nanometer regime have resulted in major reliability and variability challenges. Reliability issues such as channel hot electron injection, gate dielectric breakdown, and negative bias temperature instability (NBTI) need to be accounted for in the design of robust RF circuits. In addition, process variations in the nanoscale CMOS transistors are another major concern in today's circuits design.An adaptive gate-source biasing...
Show moreDue to continued device dimensions scaling, CMOS transistors in the nanometer regime have resulted in major reliability and variability challenges. Reliability issues such as channel hot electron injection, gate dielectric breakdown, and negative bias temperature instability (NBTI) need to be accounted for in the design of robust RF circuits. In addition, process variations in the nanoscale CMOS transistors are another major concern in today's circuits design.An adaptive gate-source biasing scheme to improve the RF circuit reliability is presented in this work. The adaptive method automatically adjusts the gate-source voltage to compensate the reduction in drain current subjected to various device reliability mechanisms. A class-AB RF power amplifier shows that the use of a source resistance makes the power-added efficiency robust against threshold voltage and mobility variations, while the use of a source inductance is more reliable for the input third-order intercept point.A RF power amplifier with adaptive gate biasing is proposed to improve the circuit device reliability degradation and process variation. The performances of the power amplifier with adaptive gate biasing are compared with those of the power amplifier without adaptive gate biasing technique. The adaptive gate biasing makes the power amplifier more resilient to process variations as well as the device aging such as mobility and threshold voltage degradation. Injection locked voltage-controlled oscillators (VCOs) have been examined. The VCOs are implemented using TSMC 0.18 (&)#181;m mixed-signal CMOS technology. The injection locked oscillators have improved phase noise performance than free running oscillators.A differential Clapp-VCO has been designed and fabricated for the evaluation of hot electron reliability. The differential Clapp-VCO is formed using cross-coupled nMOS transistors, on-chip transformers/inductors, and voltage-controlled capacitors. The experimental data demonstrate that the hot carrier damage increases the oscillation frequency and degrades the phase noise of Clapp-VCO.A p-channel transistor only VCO has been designed for low phase noise. The simulation results show that the phase noise degrades after NBTI stress at elevated temperature. This is due to increased interface states after NBTI stress. The process variability has also been evaluated.
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Date Issued
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2012
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Identifier
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CFE0004223, ucf:49000
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004223
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Title
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Analysis and Design Optimization of Resonant DC-DC Converters.
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Creator
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Fang, Xiang, Shen, Zheng, Batarseh, Issa, Mikhael, Wasfy, Wu, Xinzhang, Kutkut, Nasser, University of Central Florida
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Abstract / Description
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The development in power conversion technology is in constant demand of high power efficiency and high power density. The DC-DC power conversion is an indispensable stage for numerous power supplies and energy related applications. Particularly, in PV micro-inverters and front-end converter of power supplies, great challenges are imposed on the power performances of the DC-DC converter stage, which not only require high efficiency and density but also the capability to regulate a wide...
Show moreThe development in power conversion technology is in constant demand of high power efficiency and high power density. The DC-DC power conversion is an indispensable stage for numerous power supplies and energy related applications. Particularly, in PV micro-inverters and front-end converter of power supplies, great challenges are imposed on the power performances of the DC-DC converter stage, which not only require high efficiency and density but also the capability to regulate a wide variation range of input voltage and load conditions. The resonant DC-DC converters are good candidates to meet these challenges with the advantages of achieving soft switching and low EMI. Among the resonant converters, the LLC converter is very attractive for its high gain range and providing ZVS from full load to zero load condition. The operation of the LLC converter is complicated due to its multiple resonant stage mechanism. In this dissertation, a literature review of different analysis methods are presented, and it shows that the study on the LLC is still incomplete. Therefore, an operation mode analysis method is proposed, which divides the operation into six major modes based on the occurrence of resonant stages. The resonant currents, voltages and the DC gain characteristics for each mode is investigated. To get a thorough view of the converter behavior, the boundaries of every mode are studied, and the mode distribution is discussed. An experimental prototype is built and tested to demonstrate its accuracy in operation waveforms and gain prediction. Since most of the LLC modes have no closed-form solutions, simplification is necessary in order to utilize this mode model in practical design. As the peak gain is an important design parameters indicating the LLC's operating limit of input voltage and switching frequency, a numerical peak gain approximation method is developed, which provide a direct way to calculate the peak gain and its corresponding load and frequency condition. In addition, as PO mode is the most favorable operation mode of the LLC, its operation region is investigated and an approximation approach is developed to determine its boundary. The design optimization of the LLC has always been a difficult problem as there are many parameters affecting the design and it lacks clear design guidance in selecting the optimal resonant tank parameters. Based on the operation mode model, three optimization methods are proposed according to the design scenarios. These methods focus on minimize the conduction loss of resonant tank while maintaining the required voltage gain level, and the approximations of peak gains and mode boundary can be applied here to facilitate the design. A design example is presented following one of the optimization procedure. As a comparison, the L-C component values are reselected and tested while the design specifications are the same. The experiments show that the optimal design has better efficiency performance. Finally, a generalized approach for resonant converter analysis is developed. It can be implemented by computer programs or numerical analysis tools to derive the operation waveforms and DC characteristics of resonant converters.
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Date Issued
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2012
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Identifier
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CFE0004229, ucf:49026
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004229
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Title
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Corrosion behaviour of AISI 304 stainless steel in contact with eutectic salt for concentrated solar power plant applications.
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Creator
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Ahmed, Omar, Sohn, Yongho, Mohajeri, Nahid, Coffey, Kevin, Fang, Jiyu, University of Central Florida
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Abstract / Description
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In response to the extensive energy demands on national and global levels, concentrated solar power (CSP) plants are designed to harness and convert solar energy to electricity. For such green energy application, robust, reliable and durable materials for CSP constructions are required. The corrosion resistance is among many parameters to consider in these thermal-electrical stations such as for pipes and storage tanks in CSP. In this investigation, the corrosion behavior of AISI 304...
Show moreIn response to the extensive energy demands on national and global levels, concentrated solar power (CSP) plants are designed to harness and convert solar energy to electricity. For such green energy application, robust, reliable and durable materials for CSP constructions are required. The corrosion resistance is among many parameters to consider in these thermal-electrical stations such as for pipes and storage tanks in CSP. In this investigation, the corrosion behavior of AISI 304 stainless steel (18 wt. % Cr, 8 wt. % Ni) with the heat transfer fluid, also known as solar salt, has been examined. The ternary eutectic salt mixture with the composition, 53 wt. % KNO3, 40 wt. % NaNO2, and 7 wt. % NaNO3, that melts at 142(&)deg;C, has a potential use in CSP as a heat transfer fluid. The solar salt was prepared for this corrosion study from reagent grades of high purity nitrites and nitrates. Samples of AISI 304 stainless steel were sectioned from a sheet stock of the alloy and exposed to solar salt at 530(&)deg;C in air at 1 atmospheric pressure. After test intervals of 250, 500, and 750 hours in total immersion condition, AISI 304 stainless steel samples have developed a scale of corrosion products made up of multiple oxides. X-ray diffraction and scanning electron microscopy with X-ray energy-dispersive spectroscopy were employed to examine the extent of corrosion and identify the corrosion products. Transmission electron microscopy was used to verify the corrosion products identity via electron diffraction patterns. Oxides of iron were found to be the primary corrosion products in the presence of the molten alkali nitrates-nitrite salt mixture because of the dissolution of the protective chromium oxide (Cr2O3) scale formed on AISI 304 stainless steel coupons. The corrosion scale was uniform in thickness and made up of sodium iron oxide (NaFeO2), iron oxide, hematite (Fe2O3), and chromium-iron oxide (Cr,Fe)2O3 solid solution. The latter was found near the AISI 304 stainless steel. This indicates that the scale formed, particularly on the upper layers with presence of sodium iron oxide and iron oxide, hematite, is protective, and forms an effective barrier against penetration of fused solar salt. At the alloy interface with the bulk corrosion scale, the corrosion process induced a compositional modification in the grains located at the interface. There are iron rich and iron depleted grains at the interface if compared to the nominal iron content of the alloy. The mode of attack is identified as uniform at the test temperature of 530(&)deg;C, showing a parabolic behavior with a parabolic rate constant (Kp) equals to 1.08(&)#215;10^(-17)(m2/sec). By extrapolation, annual corrosion rate is estimated to reach 0.784 mils per year. Corrosion behavior of AISI 304 stainless steel is discussed in terms of thermodynamics and reaction paths.
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Date Issued
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2013
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Identifier
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CFE0004969, ucf:49587
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004969
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Title
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The Dollar Hegemony and the U.S.-China Monetary Disputes.
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Creator
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Cao, Xiongwei, Morales, Waltraud, Sadri, Houman, Li, Quan, University of Central Florida
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Abstract / Description
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This thesis analyzes the current disputes between the United States and China over the exchange rate of the Chinese currency renminbi using an International Political Economy (IPE) analysis. Monetary relations are not mere economic affairs, but bear geopolitical implications. Money is power. Money is politics. The pursuit of monetary power is an important part of great power politics. Based on this assertion, the thesis studies past cases of monetary power struggles between the United States...
Show moreThis thesis analyzes the current disputes between the United States and China over the exchange rate of the Chinese currency renminbi using an International Political Economy (IPE) analysis. Monetary relations are not mere economic affairs, but bear geopolitical implications. Money is power. Money is politics. The pursuit of monetary power is an important part of great power politics. Based on this assertion, the thesis studies past cases of monetary power struggles between the United States and the Great Britain, the Soviet Union, Japan, and the European Union (EU), respectively. The thesis then investigates the dollar's status as the dominant international reserve currency in the current international monetary system, as well as the power that this unique status can generate and provide. The dollar's monetary hegemony has become the main characteristic of the current international monetary system and an important power source for continued U.S. hegemony. The dollar's hegemony and the asymmetrical interdependency between the dollar and the renminbi are the source and the key basis for the recent U.S.-China monetary disagreements. The U.S.-China monetary disputes reflect not only each country's respective domestic interests and perceived benefits, but also the monetary power struggle between the two biggest global economies. Predictions are also entertained for the future monetary relations between the two countries, as well as the geopolitical implications that this relationship may have for the U.S.-China bilateral relationship in coming decades.
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Date Issued
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2012
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Identifier
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CFE0004321, ucf:49470
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004321
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Title
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HIGH-DENSITY AND HIGH-EFFICIENCY SOFT SWITCHING MODULAR BI-DIRECTIONAL DC-DC CONVERTER FOR HYBRID ELECTRIC VEHICLES.
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Creator
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Elmes, John, Batarseh, Issa, University of Central Florida
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Abstract / Description
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This dissertation presents the design of a high-density and high-efficiency soft-switching bi-directional DC-DC converter for hybrid-electric vehicles. The converter operates in a new bi-directional interleaved variable-frequency quasi-square-wave (QSW) mode, which enables high efficiency, high switching frequency, and high power-density. The converter presented utilizes a new variable frequency interleaving approach which allows for each module to operate in an interleaved position while...
Show moreThis dissertation presents the design of a high-density and high-efficiency soft-switching bi-directional DC-DC converter for hybrid-electric vehicles. The converter operates in a new bi-directional interleaved variable-frequency quasi-square-wave (QSW) mode, which enables high efficiency, high switching frequency, and high power-density. The converter presented utilizes a new variable frequency interleaving approach which allows for each module to operate in an interleaved position while allowing for tolerance in inductance and snubber capacitor values. The variable frequency interleaved soft-switching operation paired with a high-density nanocrystalline inductor and high-density system structure results in a very high performance converter, well exceeding that of the current technology. The developed converter is intended to achieve three specific performance goals: high conversion efficiency, high power density, and operation with 100 ÃÂÃÂÃÂðC coolant. Two markedly different converter prototype designs are presented, one converter using evaporative spray cooling to cool the switching devices, with the second converter using a more traditional coldplate design to cool the switching devices. The 200 kW (25 kW per module) prototype converters exhibited power density greater than 8 kilowatts/liter (kW/L), and peak efficiency over 98%, while operating with 100 ÃÂÃÂÃÂðC coolant.
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Date Issued
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2010
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Identifier
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CFE0003366, ucf:48436
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0003366
Pages