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(1 - 20 of 47)
Pages
- Title
- Stabilization system environmental disturbance modeling and analysis.
- Creator
-
Sieb, Lawrence E., Simmons, Fred O., Engineering
- Abstract / Description
-
Florida Technological University College of Engineering Thesis; Systems that operate in airborne environments and rely on the resolution provided by optical sensors require a stabilization system to isolate the line-of-sight (LOS) from the operating environment. For systems employing television sensors, stabilization accuracy is of prime importance in maintaining sufficient picture resolution to allow target identification and recognition at maximum ranges. The development of system models...
Show moreFlorida Technological University College of Engineering Thesis; Systems that operate in airborne environments and rely on the resolution provided by optical sensors require a stabilization system to isolate the line-of-sight (LOS) from the operating environment. For systems employing television sensors, stabilization accuracy is of prime importance in maintaining sufficient picture resolution to allow target identification and recognition at maximum ranges. The development of system models that accurately predict stabilization performance is important both in design trade-offs and in the system design and testing [l]. Two basic concepts are available for achieving LOS stabilization; momentum stabilization which employs a spinning mass and rate stabilization which utilizes inertial rate sensors. Previously rate stabilized platforms have been employed for high performance laser designator systems mounted in aircraft while momentum stabilized platforms have been used on tactical missiles. Rate stabilized platforms have not been used often in tactical missiles due to their higher cost and the lack of high performance stabilization requirements over large field-of-regards on the missile seekers.
Show less - Date Issued
- 1975
- Identifier
- CFR0004428, ucf:52977
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFR0004428
- Title
- Ellipsometric Measurements of Alternative Fuels.
- Creator
-
Nash, Leigh, Vasu Sumathi, Subith, Kapat, Jayanta, Ahmed, Kareem, University of Central Florida
- Abstract / Description
-
Alternative jet fuels will be important in the future to ensure cleaner burning, reliable, and reasonably priced air transportation. One important property that must meet certification standards is the fuel's thermal stability, or its ability to withstand heating before breaking down. Jet fuels are used as engine coolants, and thermally unstable fuels can form deposits in the fuel delivery systems, leading to a loss of fuel flow. In the past, the thermal stability of a fuel was rated using a...
Show moreAlternative jet fuels will be important in the future to ensure cleaner burning, reliable, and reasonably priced air transportation. One important property that must meet certification standards is the fuel's thermal stability, or its ability to withstand heating before breaking down. Jet fuels are used as engine coolants, and thermally unstable fuels can form deposits in the fuel delivery systems, leading to a loss of fuel flow. In the past, the thermal stability of a fuel was rated using a color standard method. The color of the deposit left on a metal tube that had been heated and exposed to a test fuel were matched with a color standard to rate the level of deposition, and thus the fuel's thermal stability. Ellipsometry, which is an optical technique that uses changes in a beam of light's polarization after it reflects off a sample to determine the thickness of any film on that sample, has recently been implemented to improve the thermal stability characterization standard.Various aspects of the ellipsometric method have been investigated in this work. In addition, several thermal stability studies were carried out. The effect of increasing temperature on the thermal stability of Sasol Iso-Paraffinic Kerosene, Jet A, JP-8, and Gevo jet fuel have been analyzed, and the effect of varying levels of the additive naphthalene in Sasol IPK has also been investigated. Various theoretical optical models have been evaluated for their ability to predict deposit thickness. Finally, attempts to validate these measurements were made using scanning electron microscopy, ellipsometric tube rating, interferometric tube rating, and reference tubes. The analysis carried out in this work was used to make recommendations for improving the thermal stability test standard.
Show less - Date Issued
- 2017
- Identifier
- CFE0007130, ucf:52323
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007130
- Title
- ANALYTIC & NUMERICAL STUDY OF A VORTEX MOTION EQUATION.
- Creator
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Bueller, Daniel, Rollins, David, University of Central Florida
- Abstract / Description
-
A nonlinear second order differential equation related to vortex motion is derived. This equation is analyzed using various numerical and analytical techniques including finding approximate solutions using a perturbative approach.
- Date Issued
- 2011
- Identifier
- CFE0003720, ucf:48802
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003720
- Title
- PROCESSING OF CUBIC STABILIZED ZIRCONIA ELECTROLYTE MEMBRANES FOR ELECTROLYTE-SUPPORTED SINGLE CELL SOLID OXIDE FUEL CELLS USING TAPE CASTING.
- Creator
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Coronado Rodriguez, Arturo, Orlovskaya, Nina, University of Central Florida
- Abstract / Description
-
Electrochemical conversion devices are a developing technology that prove to be a viable and more efficient alternative to current environmentally friendly generation devices. As such, constant research has been done in the last few decades to increase their applications and reliability. One of these systems, and the focus of this research, is the single cell Solid Oxide Fuel Cell (SOFC). These systems are a developing technology which main caveat is the need of high operating temperatures...
Show moreElectrochemical conversion devices are a developing technology that prove to be a viable and more efficient alternative to current environmentally friendly generation devices. As such, constant research has been done in the last few decades to increase their applications and reliability. One of these systems, and the focus of this research, is the single cell Solid Oxide Fuel Cell (SOFC). These systems are a developing technology which main caveat is the need of high operating temperatures and costs. As such, most multidisciplinary research has been focused on researching materials and/or processes that help mitigate the costs or lower the operating temperature. The research presented in this paper focused on the manufacturing of a cubic stabilized zirconia (CSZ) electrolyte thin membrane for a single cell SOFC through tape casting. Thus, the process was divided into slurry preparation, tape casting, further processing, and analysis of samples. First the tape was produced reaching optimal viscosity (between 500 to 6000 cP) and minimizing impurities. Then, the slurry was poured into the doctor's blade with a 200 micrometers gap and allowed to dry. Samples were punched from the green tape with a diameter of 28 inches. Afterwards, these samples were pressed and sintered with a force of 218016 N and temperature of 1550 degrees celsius, respectively. These steps are done to maximize density and grain growth and minimize porosity. Lastly, the tape went further analysis and it was stated that further research should be done to determine this tape viability for stationary SOFC application.
Show less - Date Issued
- 2018
- Identifier
- CFH2000414, ucf:45838
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000414
- Title
- STABILIZATION AND TRACKING OF THE VAN DER POL OSCILLATOR.
- Creator
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Zhao, Xin, Haralambous, Michael, University of Central Florida
- Abstract / Description
-
In this thesis, the stabilization and tracking problem of the Van der Pol oscillator is studied by using advanced control techniques. First, the linear state feedback and linear adaptive state feedback controllers for the stabilization problem are designed. Then, non-linear state feedback and output feedback controllers are proposed for the tracking problem with known parameters. Finally, a dynamic output feedback controller based on adaptive backstepping technique is introduced for the...
Show moreIn this thesis, the stabilization and tracking problem of the Van der Pol oscillator is studied by using advanced control techniques. First, the linear state feedback and linear adaptive state feedback controllers for the stabilization problem are designed. Then, non-linear state feedback and output feedback controllers are proposed for the tracking problem with known parameters. Finally, a dynamic output feedback controller based on adaptive backstepping technique is introduced for the tracking problem when all parameters of the Van der Pol system are unknown.
Show less - Date Issued
- 2005
- Identifier
- CFE0000569, ucf:46444
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000569
- Title
- STABILITY AND RECOVERY OF RNA IN BIOLOGICAL STAINS.
- Creator
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Setzer, Mindy Eileen, Jack Ballantyne, Dr, University of Central Florida
- Abstract / Description
-
In theory, RNA expression patterns, including the presence and relative abundance of particular RNA species, provide cell and tissue specific information that could be of use to forensic scientists. An mRNA based approach could allow the facile identification of the tissue components present in a body fluid stain and conceivably could supplant the battery of serological and biochemical tests currently employed in the forensic serology laboratory. Some of the potential advantages include...
Show moreIn theory, RNA expression patterns, including the presence and relative abundance of particular RNA species, provide cell and tissue specific information that could be of use to forensic scientists. An mRNA based approach could allow the facile identification of the tissue components present in a body fluid stain and conceivably could supplant the battery of serological and biochemical tests currently employed in the forensic serology laboratory. Some of the potential advantages include greater test specificity, and the ability to perform simultaneous analysis using a common assay format for the presence of all body fluids of forensic interest. In this report, the recovery and stability of RNA in forensic samples was evaluated by conducting an in-depth study on the persistence of RNA in biological stains. Stains were prepared from blood, saliva, semen, and vaginal secretions, and were exposed to a range of environmental conditions so that the affects of different light sources, temperatures, and environments could be assessed. Using the results from quantitation and sensitivity studies performed with pristine forensic stains, the RNA stability of samples which were collected over a period of 1 day to 1 year for blood, saliva, and vaginal secretion stains and for up to 6 months for semen stains were analyzed. The extent of RNA degradation within each type of body fluid stain was determined using quantitation of total RNA and reverse transcriptase polymerase chain reaction (RT-PCR) with selected housekeeping and tissue-specific genes. The results show that RNA can be recovered from biological stains in sufficient quantity and quality for mRNA analysis. The results also show that mRNA is detectable in samples stored at room temperature for at least one year, but that heat and humidity appear to be very detrimental to the stability of RNA.
Show less - Date Issued
- 2004
- Identifier
- CFE0000077, ucf:46141
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000077
- Title
- VARIATION OF GEOTECHNICAL STRENGTH PROPERTIES WITH AGE OF LANDFILLS ACCEPTING BIOSOLIDS.
- Creator
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Pinapati, Kishore, Chopra, Manoj, University of Central Florida
- Abstract / Description
-
The solid portion of waste disposal, known as Municipal Solid Waste (MSW) can be landfilled. Landfilling has proved to be a safe, sanitary and economical method of disposal. A by-product from wastewater treatment plants called biosolids is sometimes co-disposed along with MSW in landfills. Recent work at the University of Central Florida has focused on the behavior of the mixture of MSW and biosolids. As an increased amount of waste accumulates in these landfills, it creates a new problem &...
Show moreThe solid portion of waste disposal, known as Municipal Solid Waste (MSW) can be landfilled. Landfilling has proved to be a safe, sanitary and economical method of disposal. A by-product from wastewater treatment plants called biosolids is sometimes co-disposed along with MSW in landfills. Recent work at the University of Central Florida has focused on the behavior of the mixture of MSW and biosolids. As an increased amount of waste accumulates in these landfills, it creates a new problem – the geotechnical stability of landfills. In current literature, classical geotechnical testing methods have been followed to find the strength properties of these landfill materials. Furthermore, geotechnical methods of slope stability analyses have been employed to determine the stability of landfill slopes. As these materials have a high organic content, their strength properties may potentially change with time because of the decay of the organic materials. In the present work, an attempt is made to monitor the change in the geotechnical strength properties of the landfill materials as a function of time. Direct shear tests used for soil testing, with some modifications, were performed on cured compost samples of MSW mixed with biosolids. Geotechnical strength properties of these cured samples were compared to those of an artificially prepared mixture of MSW and biosolids, from the published literature. In addition, direct shear tests are also performed to find the interface properties of a geonet with the cured samples to check the role of a geonet in reinforcing the landfill slopes. A slope stability analysis software SLOPE/W is used to analyze the stability of the landfills. Cohesion is observed to decrease with time while the friction angle increases with time. Stability (the factor of safety against failure) of landfill slopes increases with time due to increased effective stresses and increased friction angle, as the organic material decays. This may result in additional subsidence but an increase in the effective shear strength with time. Based on the interface test results and subsequent slope stability analyses, it is found that the inclusion of a geonet improves the slope stability of a landfill. This could be a potential benefit to the landfill as reinforcement if properly placed. Based on the slope stability analysis on landfills with different slopes, it is concluded that the slope stability of a landfill is improved by keeping the slopes less steep.
Show less - Date Issued
- 2006
- Identifier
- CFE0000919, ucf:46758
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000919
- Title
- BACKGROUND STABILIZATION AND MOTION DETECTION IN LAUNCH PAD VIDEO MONITORING.
- Creator
-
Gopalan, Kaushik, Kasparis, Takis, University of Central Florida
- Abstract / Description
-
Automatic detection of moving objects in video sequences is a widely researched topic with application in surveillance operations. Methods based on background cancellation by frame differencing are extremely common. However this process becomes much more complicated when the background is not completely stable due to camera motion. This thesis considers a space application where surveillance cameras around a shuttle launch site are used to detect any debris from the shuttle. The ground shake...
Show moreAutomatic detection of moving objects in video sequences is a widely researched topic with application in surveillance operations. Methods based on background cancellation by frame differencing are extremely common. However this process becomes much more complicated when the background is not completely stable due to camera motion. This thesis considers a space application where surveillance cameras around a shuttle launch site are used to detect any debris from the shuttle. The ground shake due to the impact of the launch causes the background to be shaky. We stabilize the background by translation of each frame, the optimum translation being determined by minimizing the energy difference between consecutive frames. This process is optimized by using a sub-image instead of the whole frame, the sub-image being chosen by taking an edge detection plot of the background and choosing the area with greatest density of edges as the sub-image of interest. The stabilized sequence is then processed by taking the difference between consecutive frames and marking areas with high intensity as the areas where motion is taking place. The residual noise from the background stabilization part is filtered out by masking the areas where the background has edges, as these areas have the highest probability of false alarms due to background motion.
Show less - Date Issued
- 2005
- Identifier
- CFE0000801, ucf:46683
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000801
- Title
- USE OF VEGETATIVE MULCH AS DAILY AND INTERMEDIATE LANDFILL COVER.
- Creator
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Haddad, Assal, Reinhart, Debra, University of Central Florida
- Abstract / Description
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Management of yard waste is a significant challenge in the US, where in 2008 13.2% of the 250 million tons of municipal solid waste (MSW) was reported to be yard waste. This study describes research conducted in the laboratory and field to examine the application of vegetative mulch as daily and intermediate landfill cover. Mulch was found to exhibit stronger physical properties than soil, leading to a more stable landfill slope. Compaction of mulch was found to be significantly greater than...
Show moreManagement of yard waste is a significant challenge in the US, where in 2008 13.2% of the 250 million tons of municipal solid waste (MSW) was reported to be yard waste. This study describes research conducted in the laboratory and field to examine the application of vegetative mulch as daily and intermediate landfill cover. Mulch was found to exhibit stronger physical properties than soil, leading to a more stable landfill slope. Compaction of mulch was found to be significantly greater than soil, potentially resulting in airspace recovery. Degradation of mulch produced a soil-like material; degradation resulted in lower physical strength and hydraulic conductivity and higher bulk density when compared with fresh mulch. Mulch covers in the field permitted higher infiltration rates at high rain intensities than soil covers, and also generated less runoff due to greater porosity and hydraulic conductivity as compared to soil. Mulch covers appear to promote methane oxidation more than soil covers, although it should be noted that methane input to mulch covers was more than an order of magnitude greater than to soil plots. Life cycle assessment (LCA) showed that, considering carbon sequestration, use of green waste as landfill cover saves GHG emissions and is a better environmental management option compared to composting and use of green waste as biofuel.
Show less - Date Issued
- 2011
- Identifier
- CFE0003605, ucf:48880
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003605
- Title
- Comparison of Second Order Conformal Symplectic Schemes with Linear Stability Analysis.
- Creator
-
Floyd, Dwayne, Moore, Brian, Schober, Constance, Mohapatra, Ram, University of Central Florida
- Abstract / Description
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Numerical methods for solving linearly damped Hamiltonian ordinary differential equations are analyzed and compared. The methods are constructed from the well-known St(&)#246;rmer-Verlet and implicit midpoint methods. The structure preservation properties of each method are shown analytically and numerically. Each method is shown to preserve a symplectic form up to a constantand are therefore conformal symplectic integrators, with each method shown to accurately preserve the rate of momentum...
Show moreNumerical methods for solving linearly damped Hamiltonian ordinary differential equations are analyzed and compared. The methods are constructed from the well-known St(&)#246;rmer-Verlet and implicit midpoint methods. The structure preservation properties of each method are shown analytically and numerically. Each method is shown to preserve a symplectic form up to a constantand are therefore conformal symplectic integrators, with each method shown to accurately preserve the rate of momentum dissipation. An analytical linear stability analysis is completed for each method, establishing thresholds between the value of the damping coefficient and the step-size that ensure stability. The methods are all second order and the preservation of the rate of energy dissipation is compared to that of a third order Runge-Kutta method that does not preserve conformal properties. Numerical experiments will include the damped harmonic oscillator and the damped nonlinear pendulum.
Show less - Date Issued
- 2014
- Identifier
- CFE0005793, ucf:50051
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005793
- Title
- THE RELATIVE RECOVERABILITY OF DNA AND RNA PROFILES FROM FORENSICALLY RELEVANT BODY FLUID STAINS.
- Creator
-
Parker, Charly, Ballantyne, Jack, University of Central Florida
- Abstract / Description
-
Biological material (fluids or tissues) whether from the victim or suspect is often collected as forensic evidence, and methods to obtain and analyze the DNA found in that material have been well established. The type of body fluid (i.e. blood, saliva, semen, vaginal secretions, and menstrual blood) from which the DNA originated is also of interest, and messenger RNA typing provides a specific and sensitive means of body fluid identification. In order for mRNA profiling to be utilized in...
Show moreBiological material (fluids or tissues) whether from the victim or suspect is often collected as forensic evidence, and methods to obtain and analyze the DNA found in that material have been well established. The type of body fluid (i.e. blood, saliva, semen, vaginal secretions, and menstrual blood) from which the DNA originated is also of interest, and messenger RNA typing provides a specific and sensitive means of body fluid identification. In order for mRNA profiling to be utilized in routine forensic casework, RNA of sufficient quantity and quality must be obtained from biological fluid stains and the methods used for RNA analysis must be fully compatible with current DNA analysis methodologies. Several DNA/RNA co-extraction methods were evaluated based on the quantity and quality of DNA and RNA recovered and were also compared to standard non-co-extraction methods. The two most promising methods, the in-house developed NCFS co-extraction and the commercially available AllPrep DNA/RNA Mini kit, were then optimized by improving nucleic acid recovery and consistency of CE (capillary electrophoresis) detection results. The sensitivity of the two methods was also evaluated, and DNA and RNA profiles could be obtained for the lowest amount of blood (0.2 µL) and saliva and semen (1 µL) tested. Both extraction methods were found to be acceptable for use with forensic samples, and the ability to obtain full DNA profiles was not hindered by the co-extraction of RNA. It is generally believed that RNA is less stable than DNA which may prevent its use in forensic casework. However, the degradation rates of DNA and RNA in the same biological fluid stain have not been directly compared. To determine the relative stability of DNA and RNA, the optimized NCFS co-extraction protocol was used to isolate DNA and RNA from environmentally compromised stains. Dried blood, saliva, and semen stains and vaginal secretions swabs were incubated at set temperatures and outside for up to 1 year. Even at 56°C, DNA and RNA were both stable out to 1 year in the blood and semen stains, out to 3 months (DNA) and 1 year (RNA) in the saliva stains, and out to 6 months (DNA) and 3 months (RNA) in the vaginal secretions swabs. The recoverability of both nucleic acids was reduced when the samples were exposed to increased humidity, sunlight, and rain. In general, DNA and RNA stability was found to be similar with a loss in ability to obtain a DNA or RNA profile occurring at the same time point; however, there were instances where RNA body fluid markers were detected when a poor/no DNA profile was obtained, indicating that RNA in dried stains is sufficiently stable for mRNA body fluid typing to be used in forensic casework.
Show less - Date Issued
- 2011
- Identifier
- CFE0003596, ucf:48849
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003596
- Title
- Political, Economic, and Health Determinants of Tuberculosis Incidence.
- Creator
-
Rutherford, Ashley, Unruh, Lynn, Rohde, Kyle, Wan, Thomas, Nobles, Matt, University of Central Florida
- Abstract / Description
-
The epidemiologic transition has shifted major causes of mortality from infectious disease to chronic disease; however, infectious diseases are again re-emerging as a major global concern (Diamond, 1997; Karlen, 1995; McNeil, 1976). This research aimed to identify potential areas of infectious disease influence that are not health-related in order to help governments and policymakers establish new policies, correct current policies, or further address these issues in order to effectively...
Show moreThe epidemiologic transition has shifted major causes of mortality from infectious disease to chronic disease; however, infectious diseases are again re-emerging as a major global concern (Diamond, 1997; Karlen, 1995; McNeil, 1976). This research aimed to identify potential areas of infectious disease influence that are not health-related in order to help governments and policymakers establish new policies, correct current policies, or further address these issues in order to effectively prevent and combat infectious disease. This study employed a retrospective, cross-sectional, non-experimental design via structural equation modeling (SEM) and examined tuberculosis incidence rates at the country-level. Secondary data from open-source, international databases like World Bank's World Development Indicators, World Governance Indicators, and World Health Organization for the year 2014 was utilized. Results revealed that the latent constructs of political stability, health system indicators, and detection policies directly affected tuberculosis incidence rates; they also exhibited an indirect effect due to covariation. Economic stability did not direct affect tuberculosis incidence, but it indirectly influenced incidence through the covariation of political stability, health system indicators, and detection policies. As a country's political stability increased, tuberculosis incidence decreased. As positive health system indicators increased, tuberculosis incidence decreased. Countries with more Xpert detection policies in place experienced an apparent increase in tuberculosis incidence.
Show less - Date Issued
- 2016
- Identifier
- CFE0006842, ucf:51798
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006842
- Title
- Assessing the Effectiveness of Living Shoreline Restoration and Quantifying Wave Attenuation in Mosquito Lagoon, Florida.
- Creator
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Manis, Jennifer, Walters, Linda, Bohlen, Patrick, Jachec, Steven, University of Central Florida
- Abstract / Description
-
Coastal counties make up only 17% of the land area in the continental United States, yet 53% of the nation's population resides in these locations. With sea level rise, erosion, and human disturbances all effecting coastal areas, researchers are working to find strategies to protect and stabilize current and future shorelines. In order to maintain shoreline stability while maintaining intertidal habitat, multipurpose living shorelines have been developed to mimic natural shoreline assemblages...
Show moreCoastal counties make up only 17% of the land area in the continental United States, yet 53% of the nation's population resides in these locations. With sea level rise, erosion, and human disturbances all effecting coastal areas, researchers are working to find strategies to protect and stabilize current and future shorelines. In order to maintain shoreline stability while maintaining intertidal habitat, multipurpose living shorelines have been developed to mimic natural shoreline assemblages while preventing erosion. This project determined the effectiveness of a living shoreline stabilization containing Crassostrea virginica (eastern oyster) and Spartina alterniflora (smooth cordgrass) in the field and through controlled wave tank experiments. First, fringing oyster reefs constructed of stabilized oyster shell and smooth cordgrass plugs were placed along three eroding shoreline areas (shell middens) within Canaveral National Seashore (CANA), New Smyrna Beach, FL. For each shell midden site, four treatments (bare shoreline control, oyster shell only, S. alterniflora only, and oyster shell + S. alterniflora) were tested in replicate 3.5 x 3.5 meter areas in the lower and middle intertidal zones. Each treatment was replicated five times at each site; erosion stakes within each replicate allowed measurement of changes in sedimentation. After one year in the field, the living shoreline treatments that contained oyster shells (oyster shell only and oyster shell + S. alterniflora) vertically accreted on average 4.9 cm of sediment at two of the sites, and an average of 2.9 cm of sediment at the third, while the controls lost an average of 0.5 cm of sediment. S. alterniflora did not significantly contribute to the accretion at any site due to seagrass wrack covering and killing plants within one month of deployment. Next, the reduction in wave energy caused by these living shoreline stabilization techniques relative to bare sediment (control) was quantified. The energy reduction immediately after deployment, and the change in energy reduction when S. alterniflora had been allowed to grow for one year, and the stabilized shell was able to recruit oysters for one year was tested. Laboratory experiments were conducted in a nine-meter long wave tank using capacitance wave gauges to ultimately measure changes in wave height before and after treatments. Wave energy was calculated for each newly deployed and one-year old shoreline stabilization treatment. Boat wake characteristics from CANA shorelines were measured in the field and used as inputs to drive the physical modeling. Likewise, in the wave tank, the topography adjacent to the shell midden sites was measured and replicated. Oyster shell plus S. alterniflora attenuated significantly more wave energy than either the shells or plants alone. Also, one-year old treatments attenuated significantly more energy than the newly deployed treatments. The combination of one-year old S. alterniflora plus live oysters reduced 67% of the wave energy. With the information gathered from both the field and wave experiments, CANA chose to utilize living shorelines to stabilize three shell middens within the park. Oyster shell, marsh grass and two types of mangroves (Rhizophora mangle, Avicennia germinans) were deployed on the intertidal zones of the eroding middens. Significant accretion occurred at all middens. Two sites (Castle Windy and Garver Island) vertically accreted an average 2.3 cm of sediment after nine months, and six months respectively, and the other site (Hong Kong) received on average 1.6 cm of sediment after six months. All control areas (no stabilization) experienced sediment loss, with erosion up to 5.01 cm at Hong Kong. Plant survival was low ((<) 20%) at Castle Windy and Garver Island, while Hong Kong had moderate survival (48-65%). Of the surviving marsh grass and mangroves on the three sites, almost all ((>) 85%) had documented growth in the form of increased height or the production on new shoots. Landowners facing shoreline erosion issues, including park managers at CANA, can use this information in the future to create effective shoreline stabilization protocols. Even though the techniques will vary from location to location, the overall goal of wave attenuation while maintaining shoreline habitat remains. As the research associated with the effectiveness of living shorelines increases, we hope to see more landowners and land managers utilize this form of soft stabilization to armor shorelines.
Show less - Date Issued
- 2013
- Identifier
- CFE0004713, ucf:49809
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004713
- Title
- OPTIMAL UPFC CONTROL AND OPERATIONS FOR POWER SYSTEMS.
- Creator
-
Wu, Xiaohe, Qu, Zhihua, University of Central Florida
- Abstract / Description
-
The content of this dissertation consists of three parts. In thefirst part, optimal control strategies are developed for UnifiedPower Flow Controller (UPFC) following the clearance of faultconditions. UPFC is one of the most versatile Flexible ACTransmission devices (FACTs) that have been implemented thus far.The optimal control scheme is composed of two parts. The first isan optimal stabilization control, which is an open-loop `Bang'type of control. The second is an suboptimal damping...
Show moreThe content of this dissertation consists of three parts. In thefirst part, optimal control strategies are developed for UnifiedPower Flow Controller (UPFC) following the clearance of faultconditions. UPFC is one of the most versatile Flexible ACTransmission devices (FACTs) that have been implemented thus far.The optimal control scheme is composed of two parts. The first isan optimal stabilization control, which is an open-loop `Bang'type of control. The second is an suboptimal damping control,which consists of segments of `Bang' type control with switchingfunctions the same as those of a corresponding approximate linearsystem. Simulation results show that the proposed control strategyis very effective in maintaining stability and damping outtransient oscillations following the clearance of the fault. Inthe second part, a new power market structure is proposed. The newstructure is based on a two-level optimization formulation of themarket. It is shown that the proposed market structure can easilyfind the optimal solutions for the market while takeing factorssuch as demand elasticity into account. In the last part, amathematical programming problem is formulated to obtain themaximum value of the loadibility factor, while the power system isconstrained by steady-state dynamic security constraints. Aniterative solution procedure is proposed for the problem, and thesolution gives a slightly conservative estimate of the loadibilitylimit for the generation and transmission system.
Show less - Date Issued
- 2004
- Identifier
- CFE0000052, ucf:46122
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000052
- Title
- SLOPE STABILITY ANALYSIS OF CLASS I LANDFILLS WITH CO DISPOSAL OF BIOSOLIDS USING FIELD TEST DATA.
- Creator
-
Vajirkar, Mrutyunjay, Chopra, Dr. Manoj, University of Central Florida
- Abstract / Description
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Land filling provides a major, safe, and economical disposal route for biosolids and sludges. With an expanding world, the demand for larger and higher capacity landfills is rapidly increasing. Proper analysis and design on such fills have pushed the boundaries of geotechnical engineering practice, in terms of proper identification and assessment of strength and deformation characteristics of waste materials. The engineering properties of Municipal Solid Waste (MSW) with co-disposal of...
Show moreLand filling provides a major, safe, and economical disposal route for biosolids and sludges. With an expanding world, the demand for larger and higher capacity landfills is rapidly increasing. Proper analysis and design on such fills have pushed the boundaries of geotechnical engineering practice, in terms of proper identification and assessment of strength and deformation characteristics of waste materials. The engineering properties of Municipal Solid Waste (MSW) with co-disposal of biosolids and sludges with regards to moisture characteristics and geotechnical stability are of utmost importance. Significant changes in the composition and characteristics of landfill may take place with the addition of sludges and biosolids. In particular, the stability of waste slopes needs to be investigated, which involves the evaluation of the strength properties of the mixture of the waste and biosolids. This thesis deals with impact of the addition of biosolids on the geotechnical properties of class I landfill as determined from field investigations. The geotechnical properties are evaluated using an in-situ deep exploration test, called the Cone Penetration Test (CPT). CPT provides a continuous log of subsurface material properties using two measuring mechanisms, namely, tip resistance and side friction. The areas receiving biosolids are compared with areas without, to evaluate the effect of landfilling of biosolids. The required geotechnical shear strength parameters (angle of internal friction and cohesion) of MSW and biosolids mixture are determined by correlation with CPT results similar to the procedure followed in evaluating soil properties. The shear strength parameters obtained from the CPT data are then used to study the stability of different slope configurations of the landfill. The slope stability analysis is conducted on the various landfill models using the computer software SLOPE/W. This software was designed for soils but was found to be suitable for modeling landfills, as the waste is assumed to act similar to a cohesionless soil. Based on the field investigations, the angle of internal friction was found to be about 29° and the determination of any cohesion was not possible. It was concluded that the most suitable practical solution to adding biosolids into the landfill was in the form of trenches. From the slope stability study, it was found that the factor of safety reduces significantly with the introduction of biosolids due to a reduction in shear strength and increase in the overall moisture content. From a parametric study, the stability of a 1:2 side slope with an angle of friction lower than about 20° was found to be less than the safe limit of 1.5. In addition, the factors of safety for landfills with trenches extending close to the edges of the slopes were also found to be unsafe and this situation needs to be avoided in practice.
Show less - Date Issued
- 2004
- Identifier
- CFE0000301, ucf:46313
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000301
- Title
- Energy Expenditure and Stability During Self-Paced Walking on Different Slopes.
- Creator
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Raffaelli, Alanna, Huang, Helen, Fu, Qiushi, Kassab, Alain, University of Central Florida
- Abstract / Description
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Metabolic power and cost of transport (COT) are common quantifiers for effort when performing tasks including walking and running. Most studies focus on using a range of normal walking speeds over level ground or varied slopes. However, these studies use fixed-speed conditions. Fatigue, stability, metabolic expenditure, heart rate, and many other factors contribute to normal walking speed varying over time. This study aimed to show that allowing a subject to walk with a self-paced speed...
Show moreMetabolic power and cost of transport (COT) are common quantifiers for effort when performing tasks including walking and running. Most studies focus on using a range of normal walking speeds over level ground or varied slopes. However, these studies use fixed-speed conditions. Fatigue, stability, metabolic expenditure, heart rate, and many other factors contribute to normal walking speed varying over time. This study aimed to show that allowing a subject to walk with a self-paced speed should correlate to a minimum COT at a given slope. This study also aimed to determine if a preferred slope exists based on minimizing metabolic expenditure or maximizing stability. In this study, subjects walked at four different speed conditions including three fixed speeds (0.75 m/s, 1.0 m/s, 1.25 m/s) and their self-paced speed at five different slopes (-6(&)deg;, -3(&)deg;, 0(&)deg;, 3(&)deg;, 6(&)deg;) while metabolic energy expenditure and motion were recorded. The minimum COT occurred at a 3(&)deg; decline. At this slope, some subjects preferred to walk at a faster speed compared to level ground, whereas other subjects walked with a slower speed compared to level ground. Thus, there was a greater range of self-paced speeds, from 0.745 m/s-2.045 m/s. In comparison, at a 6(&)deg; incline, the range of self-paced speeds was much smaller, from 0.767 m/s-1.434 m/s. The variance among self-paced speeds and slope conditions between subjects suggests that COT, alone, does not explain walking decisions; stability might play a greater role than initially believed. These results provide greater insight into why humans choose to walk at a certain speed over a range of slopes and terrains.
Show less - Date Issued
- 2019
- Identifier
- CFE0007515, ucf:52629
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007515
- Title
- WEIGHTED L^P-STABILITY FOR LOCALIZED INFINITE MATRICES.
- Creator
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Shi, Qiling, Sun, Qiyu, University of Central Florida
- Abstract / Description
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This dissertation originates from a classical result that the l^p-stability of the convolution operator associated with a summable sequence are equivalent to each other for different p . This dissertation is motivated by the recent result by C. E. Shin and Q. Sun (Journal ofFunctional Analysis, 256(2009), 2417–2439), where the l^p-stability of infinite matrices in the Gohberg-Baskakov-Sjostrand class are proved to be equivalent to each other for different p. In the dissertation, for an...
Show moreThis dissertation originates from a classical result that the l^p-stability of the convolution operator associated with a summable sequence are equivalent to each other for different p . This dissertation is motivated by the recent result by C. E. Shin and Q. Sun (Journal ofFunctional Analysis, 256(2009), 2417–2439), where the l^p-stability of infinite matrices in the Gohberg-Baskakov-Sjostrand class are proved to be equivalent to each other for different p. In the dissertation, for an infinite matrix having certain off-diagonal decay, its weighted l^p-stability for different p are proved to be equivalent to each other and hence a result by Shin and Sun is generalized.
Show less - Date Issued
- 2009
- Identifier
- CFE0002685, ucf:48238
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002685
- Title
- INTEGRATED WAVELENGTH STABILIZATION OF BROAD AREA SEMICONDUCTOR LASERS USING A DUAL GRATING REFLECTOR.
- Creator
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O'Daniel, Jason, Johnson, Eric, University of Central Florida
- Abstract / Description
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A new fully integrated wavelength stabilization scheme based on grating-coupled surface-emitting lasers is explored. This wavelength stabilization scheme relies on two gratings. The first grating is fabricated on the p-side of the semiconductor laser in close proximity to the laser waveguide such that it couples light out of the guided mode of the waveguide into a propagating mode in the substrate; this grating is known as the grating coupler. The second grating is fabricated on the n-side of...
Show moreA new fully integrated wavelength stabilization scheme based on grating-coupled surface-emitting lasers is explored. This wavelength stabilization scheme relies on two gratings. The first grating is fabricated on the p-side of the semiconductor laser in close proximity to the laser waveguide such that it couples light out of the guided mode of the waveguide into a propagating mode in the substrate; this grating is known as the grating coupler. The second grating is fabricated on the n-side of the substrate such that for the stabilization wavelength, this second grating operates in the Littrow condition and is known as the feedback grating. Furthermore with the proper design of the two gratings, the feedback grating will operate under total internal reflection conditions allowing a near unity retro-reflection of the light of the stabilization wavelength. The grating coupler and feedback grating together comprise a dual grating reflector (DGR). The DGR wavelength stabilization scheme is investigated both theoretically by means of numerical modeling and experimentally by integration of a DGR as a wavelength selective reflector into a single quantum well semiconductor laser with a gain peak centered at 975nm. Numerical modeling predicts a peak reflection of approximately 70% including losses and a spectral width of 0.3nm. The integration of a DGR into a semiconductor laser proved both the efficacy of the scheme and also allowed us to experimentally determine the effective reflectivity to be on the order of 62%; the spectral width of light output from these devices is typically on the order of 0.2nm. Furthermore, these devices had light-current characteristic slopes greater than 0.84W/A operating under continuous wave conditions. The DGR was then modified to provide a reflection with two spectral peaks. A semiconductor device incorporating this dual wavelength DGR was fabricated and tested. These devices showed a peak optical power of in excess of 5.5W and a light-current characteristic slope of 0.86W/A in quasi continuous wave operation; these devices also exhibit a large operating current range in which both wavelengths have comparable output powers. Another modified DGR design was investigated for the purpose of providing an even narrower spectral reflection. Devices incorporating this modified design provided an output with a spectral width as narrow as 0.06nm. DGRs were also integrated into an extremely broad area device of an unorthodox geometry; square devices that lase in two orthogonal directions were fabricated and tested. The last idea investigated was combining a DGR wavelength stabilized laser with a tapered semiconductor optical amplifier into a master oscillator power amplifier device, with the optical coupling between the two components provided by identical grating couplers disposed on the p-side surfaces of each of the devices. These master oscillator power amplifiers provide a peak power of 32W when operating under quasi continuous wave operation.
Show less - Date Issued
- 2006
- Identifier
- CFE0001392, ucf:47004
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001392
- Title
- EFFECT OF ANNEALING ON COPPER THIN FILMS:THE CLASSICAL SIZE EFFECT AND AGGLOMERATION.
- Creator
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Gadkari, Parag, Sundaram, Kalpathy, University of Central Florida
- Abstract / Description
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With continued shrinking of CMOS technology to reduce the gate delay times, an increase in the resistivity of the metal corresponding to the wire dimension is a concern. This phenomenon of increase in resistivity with decreasing dimension of the thin metallic film or interconnect is known as the "classical size effect". Various theories have been postulated to explain the phenomenon of classical size effect; these theories can be broadly classified as resistivity due to scattering arising...
Show moreWith continued shrinking of CMOS technology to reduce the gate delay times, an increase in the resistivity of the metal corresponding to the wire dimension is a concern. This phenomenon of increase in resistivity with decreasing dimension of the thin metallic film or interconnect is known as the "classical size effect". Various theories have been postulated to explain the phenomenon of classical size effect; these theories can be broadly classified as resistivity due to scattering arising from surface and grain boundaries. The total resistivity of metals depends on the electron scattering due to impurities, phonons, surfaces, grain boundaries, and other crystal defects. Managing the size effect in a practical and manufacturing way is of major concern to the microelectronics industry. Since each of the processes (phonon, surface and grain boundary scattering) adds to the resistivity and are interrelated, it further complicates managing the size effect. However, these effects have been separately studied. In this work, the effect of annealing on the classical size effect in Cu thin films deposited on SiO2 substrate is investigated. Polycrystalline Cu thin films having thicknesses in the range of 10nm to 200nm were ultra high vacuum sputter deposited on thermally grown SiO2 surfaces. The films were annealed at temperatures in the range of 150°C to 800°C in argon and argon+3% hydrogen gases. The un-annealed Cu thin films exhibit higher resistivity than the annealed films. The resistivities of un-annealed films were in good agreement with Mayadas and Shatzkes model. When annealed the films undergoes grain growth resulting in lowering the resistivities by about 20%-30% thereby confirming the role of grain size on resistivity of the film. However, there is a limit to annealing, i.e. agglomeration phenomenon. Agglomeration is a thermally activated process resulting in a reduction of the free energy of the film–substrate system and can occur well below the melting point of the material by surface and interfacial diffusion. The reduction of film-substrate interfacial energy, film-surface interfacial energy and stresses within the film are possible driving forces for agglomeration. This work also includes the study of agglomeration phenomenon. The agglomeration behavior of Cu is investigated and compared with that of Ru, Au and Pt thin films with thicknesses in the range of 10 nm to 100 nm UHV deposited on thermally grown SiO2 substrate. The films were annealed at temperatures in the range of 150°C to 800°C in argon and argon+3% hydrogen gases. Scanning electron microscopy was used to investigate the agglomeration behavior, and transmission electron microscopy was used to characterize the microstructure of the as-deposited and annealed films. The agglomeration sequence in all the films is found to follow a two step process of void nucleation and void growth. However, void growth in Au and Pt thin films is different from Cu and Ru thin films. Residual stress and adhesion were observed to play important part in deciding the mode of void growth in Au and Pt thin films. Lastly, it is also observed that the tendency for agglomeration can be reduced by encapsulating the metal film with an oxide overlayer, which in turn improves the resistivity of the thin film due to prolonged grain growth without film breakup.
Show less - Date Issued
- 2005
- Identifier
- CFE0000496, ucf:46363
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000496
- Title
- STUDIES OF A QUANTUM SCHEDULING ALGORITHM AND ON QUANTUM ERROR CORRECTION.
- Creator
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Lu, Feng, Marinescu, Dan, University of Central Florida
- Abstract / Description
-
Quantum computation has been a rich field of study for decades because it promises possible spectacular advances, some of which may run counter to our classically rooted intuitions. At the same time, quantum computation is still in its infancy in both theoretical and practical areas. Efficient quantum algorithms are very limited in number and scope; no real breakthrough has yet been achieved in physical implementations. Grover's search algorithm can be applied to a wide range of problems;...
Show moreQuantum computation has been a rich field of study for decades because it promises possible spectacular advances, some of which may run counter to our classically rooted intuitions. At the same time, quantum computation is still in its infancy in both theoretical and practical areas. Efficient quantum algorithms are very limited in number and scope; no real breakthrough has yet been achieved in physical implementations. Grover's search algorithm can be applied to a wide range of problems; even problems not generally regarded as searching problems can be reformulated to take advantage of quantum parallelism and entanglement leading to algorithms which show a square root speedup over their classical counterparts. This dissertation discusses a systematic way to formulate such problems and gives as an example a quantum scheduling algorithm for an R||C_max problem. This thesis shows that quantum solution to such problems is not only feasible but in some cases advantageous. The complexity of the error correction circuitry forces us to design quantum error correction codes capable of correcting only a single error per error correction cycle. Yet, time-correlated errors are common for physical implementations of quantum systems; an error corrected during a certain cycle may reoccur in a later cycle due to physical processes specific to each physical implementation of the qubits. This dissertation discusses quantum error correction for a restricted class of time-correlated errors in a spin-boson model. The algorithm proposed allows the correction of two errors per error correction cycle, provided that one of them is time-correlated. The algorithm can be applied to any stabilizer code, perfect or non-perfect, and simplified the circuit complexity significantly comparing to the classic quantum error correction codes.
Show less - Date Issued
- 2007
- Identifier
- CFE0001873, ucf:47391
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001873
