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- Title
- METHODS OF EXTRAPOLATING LOW CYCLE FATIGUE DATA TO HIGH STRESS AMPLITUDES.
- Creator
-
Radonovich, David, Gordon, Ali, University of Central Florida
- Abstract / Description
-
Modern gas turbine component design applies much effort into prediction and avoidance of fatigue. Advances in the prediction of low-cycle fatigue (LCF) cracks will reduce repair and replacement costs of turbine components. These cracks have the potential to cause component failure. Regression modeling of low-cycle fatigue (LCF)test data is typically restricted for use over the range of the test data. It is often difficult to characterize the plastic strain curve fit constants when the plastic...
Show moreModern gas turbine component design applies much effort into prediction and avoidance of fatigue. Advances in the prediction of low-cycle fatigue (LCF) cracks will reduce repair and replacement costs of turbine components. These cracks have the potential to cause component failure. Regression modeling of low-cycle fatigue (LCF)test data is typically restricted for use over the range of the test data. It is often difficult to characterize the plastic strain curve fit constants when the plastic strain is a small fraction of the total strain acquired. This is often the case with high strength, moderate ductility Ni-base superalloys. The intent of this project is to identify the optimal technique for extrapolating LCF test results into stress amplitudes approaching the ultimate strength. The proposed method to accomplish this is by finding an appropriate upper and lower bounds for the cyclic stress-strain and strain-life equations. Techniques investigated include: monotonic test data anchor points, strain-compatibility, and temperature independence of the Coffin-Manson relation. A Ni-base superalloy (IN738 LC) data set with fully reversed fatigue tests at several elevated temperatures with minimal plastic strain relative to the total strain range was used to model several options to represent the upper and lower bounds of material behavior. Several high strain LCF tests were performed with stress amplitudes approaching the ultimate strength. An augmented data set was developed by combining the high strain data with the original data set. The effectiveness of the bounding equations is judged by comparing the bounding equation results with the base data set to a linear regression model using the augmented data set.
Show less - Date Issued
- 2007
- Identifier
- CFE0001891, ucf:47410
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001891
- Title
- WIRES AND LIGHT.
- Creator
-
Inguanta, Ashley, Hubbard, Susan, University of Central Florida
- Abstract / Description
-
Wires and Light is an experimental story cycle composed of fiction and hybrid pieces, which blend poetry, fiction and creative nonfiction together. The characters in these pieces are propelled by uncertainty and a strong desire to be connected to places, people. If these characters do find the connections they are searching for, most of these joining moments are fleeting. A girl, straight out of high school, misses her wonder boy, befriends a woman nearly a decade older, fists her in the...
Show moreWires and Light is an experimental story cycle composed of fiction and hybrid pieces, which blend poetry, fiction and creative nonfiction together. The characters in these pieces are propelled by uncertainty and a strong desire to be connected to places, people. If these characters do find the connections they are searching for, most of these joining moments are fleeting. A girl, straight out of high school, misses her wonder boy, befriends a woman nearly a decade older, fists her in the desert while California's on fire. A woman who dives horses off the Atlantic City Steel Pier is forced to leave her glamorous, dangerous career, which has been her entire life. The same woman meets a grieving mother years later on a train, wrestles with the idea of loving this woman, tries to understand the wall between them. A boy loses his virginity and has trouble understanding the power of his body. A young girl loses her blue horse, her best friend. Years later the same girl will deal with depression and self-mutilation, and will heal on her own. She will meet a child in a coffee shop and help her heal, too. These characters yearn for love, freedom and wholeness, and although the search is painful, they must learn to find happiness by accepting the presence of pain. These pieces are intended to show how pain affects the body, how wires can bind bodies and light can burn skin, but they don't have to. Wires can be used to collect love, keep it fastened and safe, like a guiding light.
Show less - Date Issued
- 2011
- Identifier
- CFE0003699, ucf:48830
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003699
- Title
- Investigation of Real Gas Effects on Centrifugal Compressor Analytical Methods for Supercritical CO2 Power Cycles.
- Creator
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Blanchette, Lauren, Kapat, Jayanta, Kassab, Alain, Vasu Sumathi, Subith, University of Central Florida
- Abstract / Description
-
As supercritical carbon dioxide (sCO2) power cycles have shown potential to be the next generation power cycle, an immense amount of research has gone into developing this system. One of the setbacks facing development and optimization of this cycle is the unknown in current design and analysis methods ability to accurately model turbomachinery working with sCO2. Due to the desired inlet conditions to the compressor close proximity to the critical point, accurate design and analysis of this...
Show moreAs supercritical carbon dioxide (sCO2) power cycles have shown potential to be the next generation power cycle, an immense amount of research has gone into developing this system. One of the setbacks facing development and optimization of this cycle is the unknown in current design and analysis methods ability to accurately model turbomachinery working with sCO2. Due to the desired inlet conditions to the compressor close proximity to the critical point, accurate design and analysis of this power cycle component is one of the main concerns. The present study provides aerodynamic analysis of a centrifugal compressor impeller blade with sCO2 as the working fluid through a comparative study between three dimensional (3D) computational fluid dynamics (CFD) and a one dimensional (1D) mean line analyses. The main centrifugal compressor in reference to a 100 MW sCO2 closed loop Recuperated Recompression Brayton cycle is investigated. Through the use of conventional loss correlations for centrifugal compressors found in the literature, and geometrical parameters developed through a past mean line design, losses were calculated for the specified compressor impeller. The aerodynamic performance is then predicted through the 1D analysis. Furthermore, the boundary conditions for the CFD analysis were derived through the mean line analysis of the centrifugal compressor to carry out the 3D study of the sCO2 impeller blade. As the Span and Wagner equation of state has been proven to be the most accurate when working in the vicinity of the critical point, this real gas equation of state was implemented in both analyses. Consequently, a better understanding was developed on best practices for modeling a real gas sCO2 centrifugal compressor along with the limitations that currently exist when utilizing commercial CFD solvers. Furthermore, the resulting performance and aerodynamic behavior from the 1D analysis were compared with the predicted conclusions from the CFD analysis. Past literature studies on sCO2 compressor analysis methodology have been focused on small scale power cycles. This work served as the first comparison of 1D and 3D analysis methodology for large scale sCO2 centrifugal compressors. The lack of commercial CFD codes able to model phase change within sCO2 turbomachinery and the possible breach of flow properties into the saturation region at the leading edge of the impeller blade creates a limit to the operating conditions that can be simulated within these analysis tools. Further, the rapid expansion rate within this region has been predicted to cause non-equilibrium condensation leading the fluid to a metastable vapor state. Due to the complexity of two phase models, a proposed methodology to model sCO2 compressors as single phase is to represent metastable properties through the extrapolation of equilibrium properties onto the liquid domain up until the spinodal limit. This equation of state definition with metastable properties was used to model a 3D converging-diverging nozzle due to the similar flow dynamics occurring when compared to a compressor blade channel. The equation of state was implemented through a temperature and pressure dependent property table amended with metastable properties using the NIST REFPROP Database. Modeling was performed for inlet conditions with varied closeness to the fluid's critical point. Investigation on the accuracy of utilizing this table to define sCO2 properties with respect to its resolution was executed. Through this, it was determined that the resulting interpolation error was highly influenced on the closeness to the critical point. Additionally, the effect on the capable modeling operating region when utilizing the metastable real gas property table through single phase modeling was examined.
Show less - Date Issued
- 2016
- Identifier
- CFE0006442, ucf:51466
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006442
- Title
- Sustainable Material Solution for Flexible Pavements; Performance Evaluation and Impact Assessment of Utilizing Multiple Recycled Materials in HMA.
- Creator
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Golestani, Behnam, Nam, Boo Hyun, Chopra, Manoj, Tatari, Omer, Bai, Yuanli, University of Central Florida
- Abstract / Description
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The demand for pollution-free and recyclable engineering materials has been increased as the cost of energy and environmental concerns have risen. Green material design can lead to better environmental quality and sustainability of civil infrastructure. Road construction is one of the largest consumers of natural resources. Beneficial utilization of recycled materials can result in an important opportunity to save the mining and use of virgin materials, to preserve energy, and to save...
Show moreThe demand for pollution-free and recyclable engineering materials has been increased as the cost of energy and environmental concerns have risen. Green material design can lead to better environmental quality and sustainability of civil infrastructure. Road construction is one of the largest consumers of natural resources. Beneficial utilization of recycled materials can result in an important opportunity to save the mining and use of virgin materials, to preserve energy, and to save landfill space. Two main research questions addressed in this study are: (1) How much pollution, energy, natural resources, time and money can be salvaged by applying recycling materials to Hot-Mix Asphalt (HMA)?, (2) What are the optimum mix designs for those recycled materials in HMA?, and (3) Can multiple recycled materials be used at the same time to compensate each other's drawbacks? This study evaluates the structural performance and environmental-economical cost and benefit by substituting one or a combination of three recycled materials in HMA. The three recycled materials are Recycled Asphalt Shingle (RAS), Municipal Solid Waste Incineration (MSWI) Bottom Ash, and Recycled Concrete Aggregate (RCA). Performance evaluation of the HMA including those recycled materials has been performed by a series of laboratory experimental tests while the environmental impact was investigated by the Life Cycle Assessment (LCA). In addition, Life Cycle Cost Analysis (LCCA) method has been employed to evaluate the benefit of the aforementioned recycled materials.In 2008, the Florida Legislature established a new statewide recycling goal of 75% to be achieved by the year 2020. The impact of this research aligns with this policy as it introduces a sustainable HMA that reduces the necessity of virgin aggregate and asphalt binder to 50% and 20%, respectively. In terms of environmental and economic impacts, in comparison with the regular HMA, it generates 25% less greenhouse gas emission, and for a period of 20 years, the cost of construction and maintenance would be 65% less.
Show less - Date Issued
- 2015
- Identifier
- CFE0005798, ucf:50038
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005798
- Title
- THE EFFECTS OF THE 5E LEARNING CYCLE MODEL ON STUDENTS' UNDERSTANDING OF FORCE AND MOTION CONCEPTS.
- Creator
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Campbell, Meghann, Sweeney, Aldrin, University of Central Florida
- Abstract / Description
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As advocated by the National Research Council [NRC] (1996) and the American Association for the Advancement of Science [AAAS] (1989), a change in the manner in which science is taught must be recognized at a national level and also embraced at a level that is reflected in every science teacher's classroom. With these ideas set forth as a guide for change,this study investigated the fifth grade students' understanding of force and motion concepts as they engaged in inquiry-based science...
Show moreAs advocated by the National Research Council [NRC] (1996) and the American Association for the Advancement of Science [AAAS] (1989), a change in the manner in which science is taught must be recognized at a national level and also embraced at a level that is reflected in every science teacher's classroom. With these ideas set forth as a guide for change,this study investigated the fifth grade students' understanding of force and motion concepts as they engaged in inquiry-based science investigations through the use of the 5E Learning Cycle. The researcher's journey through this process was also a focus of the study. Initial data were provided by a pretest indicating students' understanding of force and motion concepts. Four times weekly for a period of 14 weeks, students participated in investigations related to force and motion concepts. Their subsequent understanding of these concepts and their ability to generalize their understandings was evaluated via a posttest. Additionally, a review of lab activity sheets, other classroom-based assessments, and filmed interviews allowed for the triangulation of pertinent data necessary to draw conclusions from the study. Findings showed that student knowledge of force and motion concepts did increase although their understanding as demonstrated on paper lacked completeness versus understanding in an interview setting. Survey results also showed that after the study students believed they did not learn science best via textbook-based instruction.
Show less - Date Issued
- 2006
- Identifier
- CFE0001007, ucf:46831
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001007
- Title
- IDENTIFICATION OF PHYSIOLOGICAL SUBSTRATES OF PLASMODIUM FALCIPARUM PFPK5, A CDK-LIKE KINASE.
- Creator
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Sullenberger, Catherine, Chakrabarti, Debopam, University of Central Florida
- Abstract / Description
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Malaria is one of the most devastating infectious diseases causing 1-3 million fatalities a year. The majority of these cases occur amongst children in developing countries. Malarial strains in these areas are exhibiting increasing resistance to canonical treatments proving the importance of new drug targets for anti-malarials. Identification of new drug targets is dependent upon a better understanding of the molecular biology of the parasitic agent of malaria, Plasmodium. The regulation of...
Show moreMalaria is one of the most devastating infectious diseases causing 1-3 million fatalities a year. The majority of these cases occur amongst children in developing countries. Malarial strains in these areas are exhibiting increasing resistance to canonical treatments proving the importance of new drug targets for anti-malarials. Identification of new drug targets is dependent upon a better understanding of the molecular biology of the parasitic agent of malaria, Plasmodium. The regulation of Plasmodium's complex life cycle is still not well understood. Elucidation of signaling pathways involved in Plasmodium cell cycle regulation will provide insights into how the parasite thrives in human cells. A subset of kinases, referred to as cyclin-dependent kinases (CDKs), are crucial regulators of eukaryotic cell cycle progression. In silico studies show high homology between mammalian CDK's and a group of CDK-like Plasmodium kinases including PfPK5 (Plasmodium falciparum protein kinase 5). Plasmodium homologues to CDK regulators, cyclins, have also been identified. Understanding the role of PfPK5 in cell cycle regulation would require analysis of subcellular localization and cell cycle-dependent expression. Immunofluorescence assays demonstrate that PfPK5 is localized in the nucleus. PfPK5's expression profile, as determined by western blotting, shows highest expression in the schizont stage, the stage when the atypical multiple nucleated form of the parasite is observed. Possible PfPK5 interacting partners were detected by performing an anti-PfPK5 immunoprecipitation assay. Additionally, a hemagglutinin (HA)-tagged PfPK5 construct was made to increase the sensitivity of immunoprecipitation assay and identification of PfPK5 interacting partners. The characterization of PfPK5 and its interacting partners may prove useful in identification of novel drug targets in the future.
Show less - Date Issued
- 2011
- Identifier
- CFH0003848, ucf:44701
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0003848
- Title
- Gender and Conflict in Long-Term Romantic Relationships.
- Creator
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Hamlin, Emily, Sandoval, Jennifer, Parrish, Adam, Hastings, Sally, University of Central Florida
- Abstract / Description
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Conflict is inevitable, but not inherently negative. All relationships face conflict with some frequency and long-term romantic partnerships are no exception. This exploratory qualitative study investigated conflict types, approaches, and affective components using digital conflict journals. Participants logged their relational conflict for one month in order to gain insight into the communication practices and conflict perceptions of couples. A conflict cycle and sensemaking framework was...
Show moreConflict is inevitable, but not inherently negative. All relationships face conflict with some frequency and long-term romantic partnerships are no exception. This exploratory qualitative study investigated conflict types, approaches, and affective components using digital conflict journals. Participants logged their relational conflict for one month in order to gain insight into the communication practices and conflict perceptions of couples. A conflict cycle and sensemaking framework was applied to identify patterns and best practices.
Show less - Date Issued
- 2018
- Identifier
- CFE0007187, ucf:52262
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007187
- Title
- ASSESSMENT OF AQUIFER STORAGE AND RECOVERY IMPACT ON PHOSPHORUS STABILITY IN LAKE SEDIMENT.
- Creator
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Liu, Sha, Chang, Ni-bin, University of Central Florida
- Abstract / Description
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Lake Okeechobee, the second largest natural freshwater lake in the United States, had experienced a historical drought in 2007-2008 and the inflow to Lake Okeechobee has been reduced by 40% of the average daily mean between warm phase and cold phase due to the impact of Atlantic Multidecadal Oscillation in the past six decades. To cope with this water resources management problem, the US Army Corps of Engineers (USACE) proposed the largest national implementation plan of aquifer storage and...
Show moreLake Okeechobee, the second largest natural freshwater lake in the United States, had experienced a historical drought in 2007-2008 and the inflow to Lake Okeechobee has been reduced by 40% of the average daily mean between warm phase and cold phase due to the impact of Atlantic Multidecadal Oscillation in the past six decades. To cope with this water resources management problem, the US Army Corps of Engineers (USACE) proposed the largest national implementation plan of aquifer storage and recovery (ASR) project in the Kissimmee River Basin. Routine operation of ASR will deliver recovered water from ASR wells into the lake with different water quality parameters resulting in some concerns about the phosphorus stability issues at the sediment bed, which may lead to eutrophication problems. To explore the potential impacts of ASR operation on phosphorus stability in terms of adsorption, desorption, and diffusion processes, this research presented a systematic assessment based on five different mixing ratios between ASR water and lake water, and explored the sensitivity with respect to the chemical equilibrium between lake water and ASR water to predict the phosphorus stability changes in lake sediment. A series of lab-scale batch and column tests in support of a mechanistic modeling analysis provided a holistic chemical assessment as to how the phosphorus stability may be influenced by different mixing ratios. It led to an observation that the ratio of 1:10 between ASR water and lake water proved to be an optical ratio to avoid eutrophication and bring ecological benefits based on a suite of criteria.
Show less - Date Issued
- 2010
- Identifier
- CFE0003277, ucf:48527
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003277
- Title
- Biogeochemical effects of sea level rise-induced transitions within coastal wetlands.
- Creator
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Steinmuller, Havalend, Chambers, Lisa, Hinkle, Ross, Bohlen, Patrick, Beazley, Melanie, University of Central Florida
- Abstract / Description
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As sea level rise (SLR) affects coastal wetlands, ecosystem responses can include vertical accretion, landward transgression, or submergence. Sea level rise-induced transitions can alter key biogeochemical transformations within wetland soils, impacting the ability of these systems to provide ecosystem services, specifically carbon (C) storage and water quality regulation. Through a series of complementary laboratory and field-based studies, biogeochemical responses to salinity, vegetation...
Show moreAs sea level rise (SLR) affects coastal wetlands, ecosystem responses can include vertical accretion, landward transgression, or submergence. Sea level rise-induced transitions can alter key biogeochemical transformations within wetland soils, impacting the ability of these systems to provide ecosystem services, specifically carbon (C) storage and water quality regulation. Through a series of complementary laboratory and field-based studies, biogeochemical responses to salinity, vegetation shifts, and submergence were investigated. Changes in nutrient dynamics associated with saltwater intrusion were evaluated by artificially adding saline water to different freshwater wetland soil types, indicating that potential exports of critical nutrients (forms of nitrogen, phosphorus, and C) out of freshwater wetland soils is mediated by soil type. A controlled laboratory experiment was conducted to determine the potential degradability of C stored within submerging coastal wetland soils under both aerobic and anaerobic conditions. Under aerobic conditions, 66% more carbon dioxide was produced than under anaerobic conditions and 4x greater carbon dioxide was produced at 90-100cm depths than at the surface. At the same site, the degradability of carbon stores was examined through organic matter fractionation, stable isotopic examination, and determining the abundance of key microbial genes. Both total soil C and stores of bioavailable nutrients increased with depth, while organic matter quality decreased. Finally, the biogeochemical impacts of two separate vegetation transitions occurring co-incidentally with sea level rise were investigated: mangrove encroachment into salt marsh, and more salt- and inundation-tolerant herbaceous encroachment into herbaceous marsh. Conclusions from these studies demonstrate that vegetation transitions alter both soil nutrient storage and fast-cycling nutrient pools, indicating that biogeochemical transitions occur in advance of changes in vegetative species dominance. Results from these chapters holistically address how biogeochemical functioning, specifically nutrient cycling, regulation of water quality, and C sequestration, within coastal wetlands responds to stressors associated with SLR.
Show less - Date Issued
- 2019
- Identifier
- CFE0007536, ucf:52584
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007536
- Title
- Thermodynamic Analysis and Optimization of Supercritical Carbon Dioxide Brayton Cycles.
- Creator
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Mohagheghi, Mahmood, Kapat, Jayanta, Kassab, Alain, Das, Tuhin, Swami, Muthusamy, University of Central Florida
- Abstract / Description
-
The power generation industry is facing new challenging issues regarding accelerating growth of electricity demand, fuel cost and environmental pollution. These challenges accompanied by concerns of energy resources becoming scarce necessitate searching for sustainable and economically competitive solutions to supply the future electricity demand. To this end, supercritical carbon dioxide (S-CO2) Brayton cycles present great promise particularly in high temperature concentrated solar power ...
Show moreThe power generation industry is facing new challenging issues regarding accelerating growth of electricity demand, fuel cost and environmental pollution. These challenges accompanied by concerns of energy resources becoming scarce necessitate searching for sustainable and economically competitive solutions to supply the future electricity demand. To this end, supercritical carbon dioxide (S-CO2) Brayton cycles present great promise particularly in high temperature concentrated solar power (CSP) and waste heat recovery (WHR) applications. With this regard, this dissertation is intended to perform thorough thermodynamic analyses and optimization of S-CO2 Brayton cycles for both of these applications.A modeling tool has been developed, which enables one to predict and analyze the thermodynamic performance of the S-CO2 Brayton cycles in various configurations employing recuperation, recompression, intercooling and reheating. The modeling tool is fully flexible in terms of encompassing the entire feasible design domain and rectifying possible infeasible solutions. Moreover, it is computationally efficient in order to handle time consuming optimization problems. A robust optimization tool has also been developed by employing the principles of genetic algorithm. The developed genetic algorithm code is capable of optimizing non-linear systems with several decision variables simultaneously, and without being trapped in local optimum points.Two optimization schemes, i.e. single-objective and multi-objective, are considered in optimizing the S-CO2 cycles for high temperature solar tower applications. In order to reduce the size and cost of solar block, the global maximum efficiency of the power block should be realized. Therefore, the single-objective optimization scheme is considered to find the optimum design points that correspond to the global maximum efficiency of S-CO2 cycles. Four configurations of S-CO2 Brayton cycles are investigated, and the optimum design point for each configuration is determined. Ultimately, the effects of recompression, reheating, and intercooling on the thermodynamic performance of the recuperated S-CO2 Brayton cycle are analyzed. The results reveal that the main limiting factors in the optimization process are maximum cycle temperature, minimum heat rejection temperature, and pinch point temperature difference. The maximum cycle pressure is also a limiting factor in all studied cases except the simple recuperated cycle. The optimized cycle efficiency varies from 55.77% to 62.02% with consideration of reasonable component performances as we add recompression, reheat and intercooling to the simple recuperated cycle (RC). Although addition of reheating and intercooling to the recuperated recompression cycle (RRC) increases the cycle efficiency by about 3.45 percent points, the simplicity of RC and RRC configurations makes them more promising options at this early development stage of S-CO2 cycles, and are used for further studies in this dissertation.The results of efficiency maximization show that achieving the highest efficiency does not necessarily coincide with the highest cycle specific power. In addition to the efficiency, the specific power is also an important parameter when it comes to investment and decision making since it directly affects the power generation capacity, the size of components and the cost of power blocks. Consequently, the multi-objective optimization scheme is devised to simultaneously maximize both the cycle efficiency and specific power in the simple recuperated and recuperated recompression configurations. The optimization results are presented in the form of two optimum trade-off curves, also known as Pareto fronts, which enable decision makers to choose their desired compromise between the objectives, and to avoid naive solution points obtained from a single-objective optimization approach. Moreover, the comparison of the Pareto optimal fronts associated with the studied configurations reveals the optimum operational region of the recompression configuration where it presents superior performance over the simple recuperated cycle.Considering the extensive potential of waste heat recovery from energy intensive industries and stand-alone gas turbines, this dissertation also investigates the optimum design point of S-CO2 Brayton cycles for a wide range of waste heat source temperatures (500 K to 1100 K). Once again, the simple recuperated and recuperated recompression configurations are selected for this application. The utilization of heat in WHR applications is fundamentally different from that in closed loop heat source applications. The temperature pinching issues are recognized in the waste recovery heat exchangers, which brings about a trade-off between the cycle efficiency and amount of recovered heat. Therefore, maximization of net power output for a given waste heat source is of paramount practical interest rather than the maximization of cycle efficiency. The results demonstrate that by changing the heat source temperature from one application to another, the variation of optimum pressure ratio is insignificant. However, the optimum CO2 to waste gas mass flow ratio and turbine inlet temperature should properly be adjusted. The RRC configuration provides minor increase in power output as compared to RC configuration. Although cycle efficiencies as high as 34.8% and 39.7% can be achieved in RC and RRC configurations respectively, the overall conversion efficiency is less than 26% in RRC and 24.5% in RC.
Show less - Date Issued
- 2015
- Identifier
- CFE0006044, ucf:50993
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006044
- Title
- Integrated Sustainability Assessment Framework for the U.S. Transportation.
- Creator
-
Onat, Nuri, Tatari, Omer, Nam, Boo Hyun, Oloufa, Amr, Pazour, Jennifer, University of Central Florida
- Abstract / Description
-
This dissertation aims to investigate the sustainability impacts of alternative vehicle technologies and develop comprehensive sustainability assessment frameworks to analyze potential impacts of these vehicles in the U.S. In order to assess sustainability impact of vehicle alternatives, life-cycle based models has been extensively used in the literature. Although life cycle-based models are often used for environmental impacts of alternative vehicles, analysis of social and economic impacts...
Show moreThis dissertation aims to investigate the sustainability impacts of alternative vehicle technologies and develop comprehensive sustainability assessment frameworks to analyze potential impacts of these vehicles in the U.S. In order to assess sustainability impact of vehicle alternatives, life-cycle based models has been extensively used in the literature. Although life cycle-based models are often used for environmental impacts of alternative vehicles, analysis of social and economic impacts of these vehicles has gained a tremendous interest. In this regard, there is a growing interest among the international platform and academia to use the Life Cycle Sustainability Assessment framework to have more informed sustainable products, material and technology choices by considering the environmental, as well as social and economic impacts. The Life Cycle Sustainability Assessment framework is still under development and there is an ongoing research to advance it for future applications. In this dissertation, current and future needs of sustainability assessment frameworks and the U.S. transportation are identified and addressed. The major research gaps are identified as follows: (1) there has been small emphasis on effects of spatial and temporal variations on the sustainability impacts of alternative vehicle technologies, (2) no national research efforts as of now have been directed specifically toward understanding the fundamental relationship between the adoption of electric vehicles and water demand, (3) there has been a lack of understanding the dynamic complexity of transportation sustainability, encompassing feedback mechanisms, and interdependencies, for the environmental, social, and economic impacts of alternative vehicles, and (4) there is no emphasis on addressing uncertainties inherent to the U.S. transportation and its complex relationships with the environment, society, and economy.The environmental, economic, and social impacts of alternative vehicles are highly critical for truly assessing and understanding the long-term sustainability of vehicles and propose economically viable, socially acceptable, and environmentally-friendly transportation solutions for U.S. passenger transportation. This dissertation provides a more comprehensive sustainability assessment framework by realizing following objectives: (1) inclusion of spatial and temporal variations when quantifying carbon, energy, and water footprints of alternative vehicle technologies, (2) quantifying environmental, social, and economic impacts of alternative vehicle technologies, (3) capturing the dynamic relations among the parameters of U.S. transportation system, environment, society, and the economy, (4) dealing with uncertainties inherent to the U.S. transportation sector considering the complexity of the system and dynamic relationships. The results of this dissertation reveal that the results with consideration of uncertainties, temporal and spatial variations, and dynamic complex relationships among the system variables can be significantly different than those of without consideration of those. Therefore, when developing policies the robustness of proposed scenarios should be valuated with consideration of uncertainties, temporal and spatial variations as well as the dynamic feedback mechanisms. The outcomes of this study can pave the way for advancement in the state-of-the-art and state-of-the-practice in the sustainability research by presenting novel approaches to deal with uncertainties and complex systems.
Show less - Date Issued
- 2015
- Identifier
- CFE0005857, ucf:50904
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005857
- Title
- STORMWATER IRRIGATION OF SAINT AUGUSTINE GRASS:NITROGEN BALANCE AND EVAPOTRANSPIRATION.
- Creator
-
Hulstein, Ewoud, Wanielista, Martin, University of Central Florida
- Abstract / Description
-
A change in surface condition of a watershed, which is usually caused by development, can have measured effects on the naturally occurring hydrologic cycle and nitrogen cycle. This could result in environmental problems, such as reduced springflow and eutrophication. In an effort to address these issues, a combination of best management practices (BMPs) can be adhered to. The practice of using excess stormwater as a source for irrigation is proposed as a BMP for the minimization of impacts by...
Show moreA change in surface condition of a watershed, which is usually caused by development, can have measured effects on the naturally occurring hydrologic cycle and nitrogen cycle. This could result in environmental problems, such as reduced springflow and eutrophication. In an effort to address these issues, a combination of best management practices (BMPs) can be adhered to. The practice of using excess stormwater as a source for irrigation is proposed as a BMP for the minimization of impacts by development to the hydrologic and nitrogen cycles. To study the proposed BMP, a field experiment was installed in an outdoor location on the UCF main campus in Orlando, Florida. The experiment consists of three soil chambers, (2x2x4 ft, L:W:H), filled with compacted soil and covered with St. Augustine grass to simulate a suburban lawn. The grass was irrigated up to twice a week with detained stormwater with a nitrate nitrogen concentration of up to 2 mg/L. A mass balance and a total nitrogen balance were performed to determine evapotranspiration (ET) and impacts on groundwater nitrogen content. It was determined that the groundwater characteristics are largely dependent on the characteristics of the soil. The input nitrogen (precipitation and irrigation) was mostly in the form of nitrate and the output nitrogen (groundwater) was mostly in the form of ammonia. A total nitrogen mass balance indicated the mass output of nitrogen was significantly larger than mass input of nitrogen, which was due to ammonia leaching from the soil. Only small concentrations of nitrate were detected in the groundwater, resulting in an estimated nitrate removal (conversion to ammonia) of 97 percent at a depth of four feet when the input nitrate concentration was 2 mg/L. The average ET of the three chambers was compared to the estimated ET from the modified Blaney-Criddle equation on a monthly basis and a yearly basis. The modified Blaney-Criddle equation was proven to be accurate for estimating the actual ET for this application: irrigated St. Augustine grass in the Central Florida climate. In conclusion, using the available literature and the data collected from the field experiment, it was shown through an example design problem that the proposed BMP of using excess stormwater as a source for irrigation can help achieve a pre- versus postdevelopment volume balance and can help control post-development nitrate emissions.
Show less - Date Issued
- 2005
- Identifier
- CFE0000611, ucf:46511
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000611
- Title
- CONJUGATE HEAT TRANSFER ANALYSIS OF COMBINED REGENERATIVE AND DISCRETE FILM COOLING IN A ROCKET NOZZLE.
- Creator
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Pearce, Charlotte M, Kapat, Jayanta, University of Central Florida
- Abstract / Description
-
Conjugate heat transfer analysis has been carried out on an 89kN thrust chamber in order to evaluate whether combined discrete film cooling and regenerative cooling in a rocket nozzle is feasible. Several cooling configurations were tested against a baseline design of regenerative cooling only. New designs include combined cooling channels with one row of discrete film cooling holes near the throat of the nozzle, and turbulated cooling channels combined with a row of discrete film cooling...
Show moreConjugate heat transfer analysis has been carried out on an 89kN thrust chamber in order to evaluate whether combined discrete film cooling and regenerative cooling in a rocket nozzle is feasible. Several cooling configurations were tested against a baseline design of regenerative cooling only. New designs include combined cooling channels with one row of discrete film cooling holes near the throat of the nozzle, and turbulated cooling channels combined with a row of discrete film cooling holes. Blowing ratio and channel mass flow rate were both varied for each design. The effectiveness of each configuration was measured via the maximum hot gas-side nozzle wall temperature, which can be correlated to number of cycles to failure. A target maximum temperature of 613K was chosen. Combined film and regenerative cooling, when compared to the baseline regenerative cooling, reduced the hot gas side wall temperature from 667K to 638K. After adding turbulators to the cooling channels, combined film and regenerative cooling reduced the temperature to 592K. Analysis shows that combined regenerative and film cooling is feasible with significant consequences, however further improvements are possible with the use of turbulators in the regenerative cooling channels.
Show less - Date Issued
- 2016
- Identifier
- CFH2000138, ucf:45923
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000138
- Title
- Experimental and numerical investigation of a novel adsorption bed design for cooling applications.
- Creator
-
Abdelhady, Ramy, Chow, Louis, Mansy, Hansen, Das, Tuhin, Duranceau, Steven, University of Central Florida
- Abstract / Description
-
A global challenge is to develop environmentally friendly, affordable, compact and sustainable technologies to provide heating and cooling power. Adsorption cooling (AC) technology is one of the most promising ways to solve the environmental issues and cut down the energy consumption related to the traditional air conditioning and refrigeration systems. However, AC systems still suffer from poor heat and mass transfer inside the adsorption bed, which is the main obstacle to commercialization...
Show moreA global challenge is to develop environmentally friendly, affordable, compact and sustainable technologies to provide heating and cooling power. Adsorption cooling (AC) technology is one of the most promising ways to solve the environmental issues and cut down the energy consumption related to the traditional air conditioning and refrigeration systems. However, AC systems still suffer from poor heat and mass transfer inside the adsorption bed, which is the main obstacle to commercialization of adsorption cooling units. The main goal of this study is designing an efficient adsorption cooling cycle. In this research work, an in-depth scaling analysis of heat and mass transfer in an adsorption packed bed has been performed to identify and quantify how the effective thermal diffusivity of an adsorption bed and the surface diffusion rate of an adsorbate in a nanoporous adsorbent affect the specific cooling power of an adsorption cooling system. The main goal of this study is to derive new scaling parameters that can be used to specify the optimal bed dimensions and select the appropriate adsorbate/adsorbent pair to achieve the maximum cooling power. As the choice of a suitable working pair is critical for an adsorption cooling cycle, an experimental setup is designed and built to measure the adsorption kinetics and isotherms of any working pair accurately. This setup is also able to measure the dynamic performance of an adsorption bed. The equilibrium uptakes of Fuji silica-gels Type-RD and RD-2060 (manufactured by Fuji Silysia, Japan), which are commonly used in adsorption cooling systems, are measured experimentally. Based on the adsorption rate and the adsorbent temperature measured simultaneously, a new approach is proposed to measure the surface diffusivity in the temperature and pressure ranges typical of those during the operating conditions of adsorption cooling systems. In addition, the experimental measurements from the lab-scale adsorption bed are used to validate the numerical models that are commonly used for estimating the SCP of AC cycle. By using the scaling parameters driven from the scaling analysis, a newly designed packed bed for use in AC systems is proposed and evaluated in this research. The proposed design consists of repeated packed bed cells (modules). Each module is an open-cell aluminum foam packed with silica gel to enhance the overall thermal conductivity of the bed from 0.198 to 5.8 W/m.K. the experimental test rig is used to evaluate the performance on the new adsorption bed. The effect of pores per inch (PPI) of the foam, silica-gel particle size, bed height and adsorption isotherm of different types of silica gel on the bed performance are investigated.
Show less - Date Issued
- 2019
- Identifier
- CFE0007422, ucf:52702
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007422
- Title
- Flutter Stability of Shrouded Turbomachinery Cascades with Nonlinear Frictional Damping.
- Creator
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Torkaman, Alex, Kauffman, Jeffrey L., Kapat, Jayanta, Raghavan, Seetha, Mackie, Kevin, University of Central Florida
- Abstract / Description
-
Prediction of flutter in shrouded turbomachinery cascades is difficult due to i) coupling of aerodynamic drivers and structural dynamics of the cascade through shrouds, and ii) presence of nonlinear dry friction damping as a result of relative motion between adjacent shrouds. An analytical framework is developed in this dissertation to determine flutter stability of shrouded cascades with consideration of friction damping. This framework is an extension to the well-established energy method,...
Show morePrediction of flutter in shrouded turbomachinery cascades is difficult due to i) coupling of aerodynamic drivers and structural dynamics of the cascade through shrouds, and ii) presence of nonlinear dry friction damping as a result of relative motion between adjacent shrouds. An analytical framework is developed in this dissertation to determine flutter stability of shrouded cascades with consideration of friction damping. This framework is an extension to the well-established energy method, and it includes all contributing factors affecting stability of the cascade such as aerodynamic excitation and the stabilizing effects of dry friction damping caused by nonlinear contact forces between adjacent blades. This framework is developed to address a shortcoming in current analytical methods for flutter assessment in the industry. The influence of dry friction damping is typically not included due to complexity associated with nonlinearity, leading to uncertainty about exact threshold of flutter occurrence. The new analytical framework developed in this dissertation will increase the accuracy of flutter prediction method that is used for design and optimization of gas turbines.A hybrid time-frequency-time domain solution method is developed to solve aeroelastic equations of motion in both fluid and structural domains. Solution steps and their sequencing are optimized for computational efficiency with large scale realistic models and analytical accuracy in determining nonlinear friction force. Information exchange between different domains is used to couple aerodynamic and structural solutions together for a comprehensive and accurate analysis of shrouded cascade flutter problem in presence of nonlinear friction.Example application to a shrouded IGT blade shows that the influence of nonlinear friction damping in flutter suppression of an aerodynamically unstable cascade is significant. Comparison with engine test data shows that at observed vibration amplitudes in operation friction damping is sufficient to overcome aerodynamic excitation of this aerodynamically unstable cascade, resulting in overall cascade stability.
Show less - Date Issued
- 2018
- Identifier
- CFE0007379, ucf:52077
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007379
- Title
- Long-term Carbon and Copper Impact on Nutrient Removal via Green Sorption Media in Dynamic Linear Ditch Environments.
- Creator
-
Ordonez, Diana, Chang, Ni-bin, Randall, Andrew, Sadmani, A H M Anwar, University of Central Florida
- Abstract / Description
-
Nutrient-laden stormwater runoff causes environmental and ecological impacts on receiving water bodies. Biosorption Activated Media (BAM) composed of the sand, tire crumb, and clay have been implemented in stormwater best management practices due to its ability to efficiently remove nutrients from stormwater runoff, such as in roadside linear ditches, via unique chemophysical and microbiological processes. In this study, a set of fixed-bed columns were set up to simulate some external forces...
Show moreNutrient-laden stormwater runoff causes environmental and ecological impacts on receiving water bodies. Biosorption Activated Media (BAM) composed of the sand, tire crumb, and clay have been implemented in stormwater best management practices due to its ability to efficiently remove nutrients from stormwater runoff, such as in roadside linear ditches, via unique chemophysical and microbiological processes. In this study, a set of fixed-bed columns were set up to simulate some external forces in roadside linear ditches and examine how these external forces affect the performance of BAM. In our experiment, scenario 1 simulates the impact that animals such as tortoises, moles and ants produce conduits on the top layer of BAM. Scenario 2 simulates the presence of animals on BAM, together with external compaction. Finally, scenario 3 simulates external compaction such as traffic compaction alone. Furthermore, two baseline conditions were included to sustain the impact assessment of these three scenarios, respectively. They are the long-term presence of carbon in stormwater as carbon can be transported by stormwater runoff from neighboring crop fields, and the long-term presence of copper ions in stormwater as copper depositions can also be found because of electrical wiring, roofing, stormwater ponds disinfection and automobile brake pads in transportation networks. This systematic assessment encompasses some intertwined field complexity in real world systems driven by different hydraulic conditions, microbial ecology, Dissolved Organic Nitrogen (DON) reshape/removal, and long-term addition of carbon and copper (alone) on the effectiveness of total nitrogen removal. The removal efficiencies are substantially linked to varying microbial processes including mineralization, ammonification, nitrification, denitrification, and even dissimilatory nitrate reduction to ammonium, each of which is controlled by different dominant microbial species. The identification of DON compounds at the molecular level was done via a Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-IR-MS) whereas the quantitation of microbial species was done by using quantitative Polymerase Chain Reaction (qPCR). The results from the interactions between microbial ecology and DON decomposition were compared to the external forces and baseline conditions to obtain a holistic understanding of the removals efficiencies of total nitrogen. With the aid of qPCR and FT-IR-MS, this study concluded that the long-term presence of carbon is beneficial for nutrient removal whereas the long-term copper addition inhibits nutrient removal.
Show less - Date Issued
- 2019
- Identifier
- CFE0007847, ucf:52816
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007847
- Title
- Understanding sediment biogeochemistry and the role of juvenile oysters on recently restored eastern oyster reefs.
- Creator
-
Locher, Bryan, Chambers, Lisa, Walters, Linda, Kibler, Kelly, University of Central Florida
- Abstract / Description
-
In recent decades, goals for the restoration of eastern oyster (Crassostrea virginica) populations along the eastern coast of the United States have shifted from increasing harvestable oyster fisheries to enhancing the range of ecosystem services provided by oyster reefs. By filtering large volumes of water and releasing nutrient-rich feces and pseudofeces, oysters can locally enhance sediment biogeochemical cycling compared to that of unstructured benthic environments. An ongoing restoration...
Show moreIn recent decades, goals for the restoration of eastern oyster (Crassostrea virginica) populations along the eastern coast of the United States have shifted from increasing harvestable oyster fisheries to enhancing the range of ecosystem services provided by oyster reefs. By filtering large volumes of water and releasing nutrient-rich feces and pseudofeces, oysters can locally enhance sediment biogeochemical cycling compared to that of unstructured benthic environments. An ongoing restoration program in Mosquito Lagoon, FL was leveraged to assess the immediate impacts ((<) 1 year) of restoration on sediment biogeochemical properties of oyster reefs. The first study measured both short-term and long-term pools of carbon, nitrogen and phosphorus on dead, natural and restored reefs periodically over one year. The second study investigated one of the contributions to sediment nutrient pools by comparing feeding and feces/pseudofeces nutrient content of juvenile and older oysters. Results show that inorganic nitrogen and phosphorus pools can change within weeks after restoration and total nutrient pools by 6 months post-restoration. Restored reefs experienced a 136 % increase in ammonium, 78 % increase in total nitrogen, 46 % increase in total phosphorus, and 75 % increase in organic matter concentrations after 12 months of restoration. These nutrient increases were all positively correlated with oyster density, shell length and reef height measured on each reef. When standardized to grams of dry tissue weight, juvenile oysters showed significantly higher rates of chlorophyll-a removal, release of ammonium, and biodeposits with higher concentrations of dissolved organic carbon, nitrite + nitrate, and ammonium. The short-term changes to biogeochemical cycling on eastern oyster reefs within the first year of restoration are important to managers seeking to monitor ecosystem service recovery and overall coastal ecosystem health.
Show less - Date Issued
- 2019
- Identifier
- CFE0007671, ucf:52460
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007671
- Title
- AN UNCERTAINTY QUANTIFICATION OF THE VARIATION OF INTERNAL HEAT TRANSFER COEFFICIENTS AND THE EFFECT ON AIRFOIL LIFE.
- Creator
-
Marsh, Jan, Kapat, Jayanta, University of Central Florida
- Abstract / Description
-
Uncertainty in accurately knowing applied internal heat transfer coefficients inside of a cooling passage can lead to variability in predicting low cycle fatigue life of a turbine vane or blade. Under-predicting a life value for a turbine part can have disastrous effects on the engine as a whole, and can negate efforts in innovative design for advanced cooling techniques for turbine components. Quantification of this fatigue life uncertainty utilizing a computational framework is the primary...
Show moreUncertainty in accurately knowing applied internal heat transfer coefficients inside of a cooling passage can lead to variability in predicting low cycle fatigue life of a turbine vane or blade. Under-predicting a life value for a turbine part can have disastrous effects on the engine as a whole, and can negate efforts in innovative design for advanced cooling techniques for turbine components. Quantification of this fatigue life uncertainty utilizing a computational framework is the primary objective of this thesis. Through the use of probabilistic design methodologies a process is developed to simulate uncertainties of internal heat transfer coefficient, which are then applied to the aft section of a non-rotating turbine blade component, internally cooled through a multi-pass serpentine channel. While keeping all other parameters constant internal heat transfer coefficients are varied according to a prescribed uncertainty range throughout the passages. The effect on the low cycle fatigue life of the airfoil is then evaluated at three discrete locations: near the base of the airfoil, towards the tip, and at mid-span. A generic low cycle fatigue life prediction model is used for these evaluations. Even though the probabilistic design process uses independent random numbers to simulate the variation, in reality, heat transfer coefficients at points located closely together should be correlated. For this reason, an autocorrelation function is implemented. By changing the value of this function the strength of the correlation of neighboring internal heat transfer coefficients to each other over a certain distance can be controlled. In order to test the effect that this correlation strength has on the low cycle fatigue life calculation, low and high values are chosen and analyzed. The magnitude of the prescribed uncertainty range of the internal heat transfer coefficient variation is varied to further study the effects on life. Investigated values include 5%, 10% and 20% for the straight ribbed passages and 10%, 20%, and 40% for both the tip and hub turns. As expected there is a significant dependence of low cycle fatigue life to the variation in internal heat transfer coefficients. For the 20/40% case, variations in life as high as 50-60% are recorded, furthermore a trend is observed showing that as the magnitude of the uncertainty range of internal heat transfer coefficients narrows so does the range of the low cycle fatigue life uncertainty.
Show less - Date Issued
- 2010
- Identifier
- CFE0003496, ucf:48975
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003496
- Title
- DIGITAL RESEARCH CYCLES: HOW ATTITUDES TOWARD CONTENT, CULTURE AND TECHNOLOGY AFFECT WEB DEVELOPMENT.
- Creator
-
Scott, Edward, Saper, Craig, University of Central Florida
- Abstract / Description
-
It has been estimated that one third of the world's population does not have access to "adequate" health care. Some 1.6 billion people live in countries experiencing "concentrated" acquired immune deficiency syndrome (AIDS) epidemics. Many countries in Africa -- and other low-income countries -- are in dire need of help providing adequate health care services to their citizens. They require more hands-on care from Western health workers -- and training so more African health workers can...
Show moreIt has been estimated that one third of the world's population does not have access to "adequate" health care. Some 1.6 billion people live in countries experiencing "concentrated" acquired immune deficiency syndrome (AIDS) epidemics. Many countries in Africa -- and other low-income countries -- are in dire need of help providing adequate health care services to their citizens. They require more hands-on care from Western health workers -- and training so more African health workers can eventually care for their own citizens. But these countries also need assistance acquiring and implementing both texts -- the body of medical information potentially available to them -- and technology -- the means by which that information can be conveyed. This dissertation looks at these issues and others from a multi-faceted approach. It combines a survey of the developers of Web sites designed for use by health workers in low-income countries and a proposal for a novel approach to communication theory, which could help improve health communication and other social marketing practices. It also includes an extensive review of literature regarding a number of topics related to these issues. To improve healthcare services in low-income countries, several things should occur. First, more health workers -- and others -- could visit African countries and other places to provide free, hands-on medical care, as this researcher's group did in Uganda. Such trips are ideal occasions for studying the cultural differences between "mzungu" (white man) and the Ugandan people. A number of useful medical texts have been written for health workers in low-income countries. Others will be published as new health information becomes available. But on what medium will they be published? Computers? Personal digital assistants? During the past 10 years the Internet became an ideal venue for conveying information. Unfortunately, people in target countries such as Uganda encounter cultural differences when such new technologies are diffused. This dissertation looks at cultural and technological difficulties encountered by people in low-income countries who attempt to diffuse information and communication technologies (ICT). Once a technology has been successfully adopted, someone will look for ways to use it to help others. There are hundreds of sites on the Internet -- built by Web developers in Western countries -- that are designed for use by health workers in low-income countries. However, these Web developers also experience cultural and technological differences, based on their knowledge of and attitudes toward best practices in their field. This research includes a survey of Web developers which determined their attitudes toward best practices in their field and tested this researcher's hypothesis that there is no significant difference among the developers' attitudes toward the content on their sites, their audience's cultural needs and the various technological needs their audience has. It was found that the Web developers agree with 17 of 18 perceived best practices and that there is a significant difference between Web developers' attitudes toward their audience's technological needs and their attitudes toward quality content and the audience's cultural needs. Creation of the survey herein resulted in this researcher generating a new way of thinking about communication theory -- called digital research cycles. The survey was based on a review of literature and is rooted in the belief that any successful communication of a computer-mediated message in the information age is a behavior which is influenced by the senders' and receivers' attitudes and knowledge about textual style, the audience, technology and the subject matter to which the message pertains.
Show less - Date Issued
- 2009
- Identifier
- CFE0002637, ucf:48218
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002637
- Title
- A Generational Perspective on the Development of the Political History of Modern Iran.
- Creator
-
McDowall, Gregory, Sadri, Houman, Knuckey, Jonathan, Kang, Kyungkook, University of Central Florida
- Abstract / Description
-
Mark Twain once remarked, (")History doesn't repeat itself, but it does rhyme.(") If such recurrences happen with some discernible periodicity it would support the view that society develops cyclically. Though still controversial, this perspective has found a home in the long wave cycle theories of economics and international relations. For decades, international relation theorists have argued over which factor has primarily driven the interstate system, but this paradigm transforms that...
Show moreMark Twain once remarked, (")History doesn't repeat itself, but it does rhyme.(") If such recurrences happen with some discernible periodicity it would support the view that society develops cyclically. Though still controversial, this perspective has found a home in the long wave cycle theories of economics and international relations. For decades, international relation theorists have argued over which factor has primarily driven the interstate system, but this paradigm transforms that debate into a query over which of them serves as the medium for carrying waves of social change, be it war, trade, class, or gender relations. William Strauss and Neil Howe, however, found that there is no medium. Instead, long wave cycles result from oscillations of the supply and demand for order due to generational turnover. Essentially, it is a method of error correction, of stabilizing society against the forces of disruptive change wrought by modernity. Though it broadly encompasses many long wave cycle theories, it has yet to be applied to study the modern history of a developing country. Iran offers such a case to test the limits of Strauss and Howe's theory, which this study will perform by comparing its history over the last two centuries, particularly since the turn of the twentieth century, to their theory's expectations. Moreover, in accounting for the deviations, this study attempts to extend their theory to include the modernization process itself, and how it relates to the generational cycle.
Show less - Date Issued
- 2015
- Identifier
- CFE0006226, ucf:51083
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006226
