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Pages
- Title
- Resilience of Bridges Following Aftershocks.
- Creator
-
Espinosa, Diego, Mackie, Kevin, Chopra, Manoj, Tatari, Mehmet, University of Central Florida
- Abstract / Description
-
The ability to predict the reduction in capacity of a structure after an earthquake is vital in the process of assessing a structure after a main-shock or an after-shock. Main-shocks are normally followed by a few aftershocks in a short period of time. Researchers in the past have focused for the most part on the effects of main-shocks on buildings. Very little research has been performed on the ability to predict the reduction in capacity of bridges in aftershocks. This thesis focuses on...
Show moreThe ability to predict the reduction in capacity of a structure after an earthquake is vital in the process of assessing a structure after a main-shock or an after-shock. Main-shocks are normally followed by a few aftershocks in a short period of time. Researchers in the past have focused for the most part on the effects of main-shocks on buildings. Very little research has been performed on the ability to predict the reduction in capacity of bridges in aftershocks. This thesis focuses on providing a way of assessing the reduction in capacity for main-shocks as compared to aftershocks and the effects and importance of both in a bridge. The reduction in capacity was defined using three different ratios: ultimate force, stiffness, and strain energy ratio. The ratios were computed relative to an undamaged state following both the main-shock scenario and the main-shock combined with aftershock scenario. The force, stiffness, and strain energy quantities were obtained from lateral pushover analyses along the two lateral bridge axes. Probabilistic demand models describing the loss in capacity were formulated by pairing intensity measures, based on real ground motions obtained from previous earthquakes, for the main-shock and aftershock with the capacity ratios, obtained from nonlinear dynamic time history analysis. Additionally, the reduction in capacity was conditioned on residual displacement and intensity measure in an attempt to discover the reduction in capacity ratio due to the contribution of residual displacement and therefore separate contributions from geometrical and material nonlinearities. This thesis demonstrates that the usage of strain energy ratio provides a definition of capacity that ultimately provides the best correlation between capacity and intensity measure.
Show less - Date Issued
- 2012
- Identifier
- CFE0004311, ucf:49494
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004311
- Title
- ENERGY-USE BEHAVIOR AMONG COLLEGE STUDENTS.
- Creator
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O'Connell, Lillian, Canan, Penelope, University of Central Florida
- Abstract / Description
-
As the effects of global climate change become increasingly apparent, many concerned individuals are making efforts to reduce their greenhouse gas emissions. One simple and effective method of reducing oneÂÂ's personal carbon footprint is through energy conservation behavior. Studies have shown that occupant behavior can control as much as 50% of residential energy use and that energy use varies widely between residences with the same number of occupants depending on...
Show moreAs the effects of global climate change become increasingly apparent, many concerned individuals are making efforts to reduce their greenhouse gas emissions. One simple and effective method of reducing oneÂÂ's personal carbon footprint is through energy conservation behavior. Studies have shown that occupant behavior can control as much as 50% of residential energy use and that energy use varies widely between residences with the same number of occupants depending on consumption behavior. In light of this, energy conservation behavior is a valuable method of reducing greenhouse gas emissions and curbing the effects of climate change. Motivating people to conserve energy could have profound positive effects on the environment. The following study applies Icek AjzenÂÂ's Theory of Planned Behavior (1991) to energy conservation behavior among college students in the state of Florida. This research tests the hypothesis that pro-environmental attitudes, influence of peers, and a high level of perceived control over behavior have a significant impact on energy conservation behavior.
Show less - Date Issued
- 2010
- Identifier
- CFE0003183, ucf:48614
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003183
- Title
- Self-Scaling Evolution of Analog Computation Circuits.
- Creator
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Pyle, Steven, DeMara, Ronald, Vosoughi, Azadeh, Chanda, Debashis, University of Central Florida
- Abstract / Description
-
Energy and performance improvements of continuous-time analog-based computation for selected applications offer an avenue to continue improving the computational ability of tomorrow's electronic devices at current technology scaling limits. However, analog computation is plagued by the difficulty of designing complex computational circuits, programmability, as well as the inherent lack of accuracy and precision when compared to digital implementations. In this thesis, evolutionary algorithm...
Show moreEnergy and performance improvements of continuous-time analog-based computation for selected applications offer an avenue to continue improving the computational ability of tomorrow's electronic devices at current technology scaling limits. However, analog computation is plagued by the difficulty of designing complex computational circuits, programmability, as well as the inherent lack of accuracy and precision when compared to digital implementations. In this thesis, evolutionary algorithm-based techniques are utilized within a reconfigurable analog fabric to realize an automated method of designing analog-based computational circuits while adapting the functional range to improve performance. A Self-Scaling Genetic Algorithm is proposed to adapt solutions to computationally-tractable ranges in hardware-constrained analog reconfigurable fabrics. It operates by utilizing a Particle Swarm Optimization (PSO) algorithm that operates synergistically with a Genetic Algorithm (GA) to adaptively scale and translate the functional range of computational circuits composed of high-level or low-level Computational Analog Elements to improve performance and realize functionality otherwise unobtainable on the intrinsic platform. The technique is demonstrated by evolving square, square-root, cube, and cube-root analog computational circuits on the Cypress PSoC-5LP System-on-Chip. Results indicate that the Self-Scaling Genetic Algorithm improves our error metric on average 7.18-fold, up to 12.92-fold for computational circuits that produce outputs beyond device range. Results were also favorable compared to previous works, which utilized extrinsic evolution of circuits with much greater complexity than was possible on the PSoC-5LP.
Show less - Date Issued
- 2015
- Identifier
- CFE0005866, ucf:50873
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005866
- Title
- Research on Improving Reliability, Energy Efficiency and Scalability in Distributed and Parallel File Systems.
- Creator
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Zhang, Junyao, Wang, Jun, Zhang, Shaojie, Lee, Jooheung, University of Central Florida
- Abstract / Description
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With the increasing popularity of cloud computing and "Big data" applications, current data centers are often required to manage petabytes or exabytes of data. To store this huge amount of data, thousands or tens of thousands storage nodes are required at a single site. This imposes three major challenges for storage system designers: (1) Reliability---node failure in these datacenters is a normal occurrence rather than a rare situation. This makes data reliability a great concern. (2) Energy...
Show moreWith the increasing popularity of cloud computing and "Big data" applications, current data centers are often required to manage petabytes or exabytes of data. To store this huge amount of data, thousands or tens of thousands storage nodes are required at a single site. This imposes three major challenges for storage system designers: (1) Reliability---node failure in these datacenters is a normal occurrence rather than a rare situation. This makes data reliability a great concern. (2) Energy efficiency---a data center can consume up to 100 times more energy than a standard office building. More than 10% of this energy consumption can be attributed to storage systems. Thus, reducing the energy consumption of the storage system is key to reducing the overall consumption of the data center.(3) Scalability---with the continuously increasing size of data, maintaining the scalability of the storage systems is essential. That is, the expansion of the storage system should be completed efficiently and without limitations on the total number of storage nodes or performance.This thesis proposes three ways to improve the above three key features for current large-scale storage systems. Firstly, we define the problem of "reverse lookup", namely finding the list of objects (blocks) for a failed node. As the first step of failure recovery, this process is directly related to the recovery/reconstruction time. While existing solutions use metadata traversal or data distribution reversing methods for reverse lookup, which are either time consuming or expensive, a deterministic block placement can achieve fast and efficient reverse lookup.However, the deterministic placement solutions are designed for centralized, small-scale storage architectures such as RAID etc.. Due to their lacking of scalability, they cannot be directly applied in large-scale storage systems. In this paper, we propose Group-Shifted Declustering (G-SD), a deterministic data layout for multi-way replication. G-SD addresses the scalability issue of our previous Shifted Declustering layout and supports fast and efficient reverse lookup.Secondly, we define a problem: "how to balance the performance, energy, and recovery in degradation mode for an energy efficient storage system?". While extensive researches have been proposed to tradeoff performance for energy efficiency under normal mode, the system enters degradation mode when node failure occurs, in which node reconstruction is initiated. This very process requires a number of disks to be spun up and requires a substantial amount of I/O bandwidth, which will not only compromise energy efficiency but also performance. Without considering the I/O bandwidth contention between recovery and performance, we find that the current energy proportional solutions cannot answer this question accurately. This thesis present PERP, a mathematical model to minimize the energy consumption for a storage systems with respect to performance and recovery. PERP answers this problem by providing the accurate number of nodes and the assigned recovery bandwidth at each time frame.Thirdly, current distributed file systems such as Google File System(GFS) and Hadoop Distributed File System (HDFS), employ a pseudo-random method for replica distribution and a centralized lookup table (block map) to record all replica locations. This lookup table requires a large amount of memory and consumes a considerable amount of CPU/network resources on the metadata server. With the booming size of "Big Data", the metadata server becomes a scalability and performance bottleneck. While current approaches such as HDFS Federation attempt to "horizontally" extend scalability by allowing multiple metadata servers, we believe a more promising optimization option is to "vertically" scale up each metadata server. We propose Deister, a novel block management scheme that builds on top of a deterministic declustering distribution method Intersected Shifted Declustering (ISD). Thus both replica distribution and location lookup can be achieved without a centralized lookup table.
Show less - Date Issued
- 2015
- Identifier
- CFE0006238, ucf:51082
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006238
- Title
- GETTING TO NET ZERO ENERGY BUILDINGS: A HOLISTIC TECHNO-ECOLOGICAL MODELING APPROACH.
- Creator
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Alirezaei, Mehdi, Tatari, Omer, Oloufa, Amr, Nam, Boo Hyun, Xanthopoulos, Petros, University of Central Florida
- Abstract / Description
-
Buildings in the United States are responsible for more than 40% of the primary energy and 70% of electricity usage and greatly in CO2 emission by about 39%, more than any other sector including transportation and industry sectors. This energy consumption is expected to grow mainly due to increasing trends in new buildings construction. Rising energy prices alongside with energy independencies, limited resources, and climate change have made the current situation even worse. An Energy...
Show moreBuildings in the United States are responsible for more than 40% of the primary energy and 70% of electricity usage and greatly in CO2 emission by about 39%, more than any other sector including transportation and industry sectors. This energy consumption is expected to grow mainly due to increasing trends in new buildings construction. Rising energy prices alongside with energy independencies, limited resources, and climate change have made the current situation even worse. An Energy Efficient (EE) building is able to reduce the heating and cooling load significantly compared with a code compliant building. Furthermore, integrating renewable energy sources in the building energy portfolio could drive the building's grid reliance further down. Such buildings that are able to passively save and actively produce energy are called Net Zero Energy Buildings (NZEB). Despite all new energy efficient technologies, reaching NZEB is challenging due to high first cost of super-efficient measures and renewable energy sources as well as integration of the newly on-site generated electricity to the grid. Achieving NZEB without looking at its surrounding environment may result in sub-optimal solutions. Currently, 95% of American households own a car, and with the help of newly introduced Vehicle to Home (V2H) technologies, building, vehicle, renewable energy sources, and ecological environment can work together as a techno-ecological system to fulfill the requirement of an NZEB ecosystem.Due to the great flexibility of electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) in interacting with the power grid, they will play a significant role in the future of the power system. In a large scale, an organized fleet of EVs can be considered as reliable and flexible power storage for a set of building blocks or in a smaller scale, individual EV owners can use their own vehicles as a source of power alongside with other sources of power. To this end, V2H technologies can utilize idle EV battery power as an electricity storage tool to mitigate fluctuations in renewable electric power supply, to provide electricity for the building during the peak time, and to help in supplying electricity during emergency situation and power outage. V2H is said to be the solution to a successful integration of renewables and at the same time maintaining the integrity of the grid. This happens through depleting the stored power in the battery of EV and then charging the battery when the demand is low, using the electricity provided by grid or renewables. Government incentives can play an important role in employing this technology by buying out the high first time cost request. According to Energy Information Administration (EIA), U.S. residential utility customers consume 29.95 kWh electricity on average per household-day. With the current technology, EV batteries could store up to 30 kWh electricity. As a result, even for a code compliant house, a family could use EV battery as a source of energy for one normal day operation. For an energy efficient home, there could even be a surplus of energy that could be transferred to the grid. In summary, Achieving NZEB is facing various obstacles and removing these barriers require a more holistic view on a greater system and environment, where a building interacts with on-site renewable energy sources, EV, and its surrounded ecological environment.This dissertation aims to utilize the application of Vehicle to Home technology to reach NZEB by developing two new models in two phases; the macro based excel model (NZEB-VBA) and agent based model (NZEB-ABM). Using these two models, homeowners can calculate the savings through implementing abovementioned technologies which can be considered as a motivation to move toward greener buildings. In the first step, an optimization analysis is performed first to select the best design alternatives for an energy-efficient building under the relevant economic and environmental constraints. Next, solar photovoltaic sources are used to supply the building's remaining energy demand and thereby minimize the building's grid reliance. Finally, Vehicle to Home technology is coupled with the renewable energy source as a substitute for power from the grid. The whole algorithm for this process will be running in the visual basic environment.In the second phase of the study, the focus is more on the dynamic interaction of different components of the system with each other. Although the general procedure is the same, the modeling will take place in a different environment. Showing the status of different parts of the system at any specific time, changing the values of different parameters of the system and observing the results, and investigating the impact of each parameter's on overall behavior of the system are among the advantages of the agent based model. Having real time data can greatly enhance the capabilities of this system. The results indicate that, with the help of energy-efficient design features and a properly developed algorithm to draw electricity from EV and solar energy, it is possible to reduce the required electricity from the power grid by 59% when compared to a standard energy-efficient building and by as much as 90% when compared to a typical code-compliant building. This thereby reduces the electricity cost by 1.55 times the cost of the conventional method of drawing grid electricity. This savings can compensate the installation costs of solar panels and other technologies necessary for a Net Zero Energy Building. In the last phase of the study, a regional analysis will be performed to investigate the effect of different weather conditions, traffic situation and driving behavior on the behavior of this system.
Show less - Date Issued
- 2016
- Identifier
- CFE0006830, ucf:51797
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006830
- Title
- Dynamic Modeling of Autorotation for Simultaneous Lift and Wind Energy Extraction.
- Creator
-
Mackertich, Sadaf, Das, Tuhin, Moslehy, Faissal, Xu, Yunjun, University of Central Florida
- Abstract / Description
-
The goal of this thesis is to develop a multi-body dynamics model of autorotation with the objective of studying its application in energy harvesting. A rotor undergoing autorotation is termed an Autogyro. In the autorotation mode, the rotor is unpowered and its interaction with the wind causes an upward thrust force. The theory of an autorotating rotorcraft was originally studied for achieving safe flight at low speeds and later used for safe descent of helicopters under engine failure. The...
Show moreThe goal of this thesis is to develop a multi-body dynamics model of autorotation with the objective of studying its application in energy harvesting. A rotor undergoing autorotation is termed an Autogyro. In the autorotation mode, the rotor is unpowered and its interaction with the wind causes an upward thrust force. The theory of an autorotating rotorcraft was originally studied for achieving safe flight at low speeds and later used for safe descent of helicopters under engine failure. The concept can potentially be used as a means to collect high-altitude wind energy. Autorotation is inherently a dynamic process and requires detailed models for characterization. Existing models of autorotation assume steady operating conditions with constant angular velocity of the rotor. The models provide spatially averaged aerodynamic forces and torques. While these steady-autorotation models are used to create a basis for the dynamic model developed in this thesis, the latter uses a Lagrangian formulation to determine the equations of motion. The aerodynamic effects on the blades that produce thrust forces, in-plane torques, and out-of-plane torques, are modeled as non-conservative forces within the Lagrangian framework. To incorporate the instantaneous aerodynamic forces, the above-mentioned spatial averaging is removed. The resulting model is causal and consists of a system of differential equations. To investigate the dynamics under energy-harvesting operation, an additional in-plane regenerative torque is added to simulate the effect of a generator. The aerodynamic effects of this regenerative braking is incorporated into the model. In addition, the dynamic model relaxes assumptions of small flapping angles, and the periodic flapping behavior of the blades are naturally generated by the dynamics instead of assuming Fourier expansions. The dynamic model enables the study of transients due to change in operating conditions or external influences such as wind speeds. It also helps gain insight into force and torque fluctuations.Model verification is conducted to ensure that the dynamic model produces similar steady-operating conditions as those reported in prior works. In addition, the behavior of autorotation under energy harvesting is evaluated. The thesis also explores the viability of achieving sufficient lift while extracting energy from prevailing winds. A range of regenerative torques are applied to determine the optimal energy state. Finally, a complete high-altitude energy harvesting system is modeled by incorporating a tether utilizing a catenary model. Overall, the thesis lends support to the hypothesis that a tethered autogyro can support its weight while harvesting energy from strong wind-fields, when augmented with appropriate control systems.
Show less - Date Issued
- 2016
- Identifier
- CFE0006138, ucf:51173
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006138
- Title
- Resource allocation and load-shedding policies based on Markov decision processes for renewable energy generation and storage.
- Creator
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Jimenez, Edwards, Atia, George, Richie, Samuel, Pazour, Jennifer, University of Central Florida
- Abstract / Description
-
In modern power systems, renewable energy has become an increasingly popular form of energy generation as a result of all the rules and regulations that are being implemented towards achieving clean energy worldwide. However, clean energy can have drawbacks in several forms. Wind energy, for example can introduce intermittency. In this thesis, we discuss a method to deal with this intermittency. In particular, by shedding some specific amount of load we can avoid a total system breakdown of...
Show moreIn modern power systems, renewable energy has become an increasingly popular form of energy generation as a result of all the rules and regulations that are being implemented towards achieving clean energy worldwide. However, clean energy can have drawbacks in several forms. Wind energy, for example can introduce intermittency. In this thesis, we discuss a method to deal with this intermittency. In particular, by shedding some specific amount of load we can avoid a total system breakdown of the entire power plant. The load shedding method discussed in this thesis utilizes a Markov Decision Process with backward policy iteration. This is based on a probabilistic method that chooses the best load-shedding path that minimizes the expected total cost to ensure no power failure. We compare our results with two control policies, a load-balancing policy and a less-load shedding policy. It is shown that the proposed MDP policy outperforms the other control policies and achieves the minimum total expected cost.
Show less - Date Issued
- 2015
- Identifier
- CFE0005635, ucf:50222
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005635
- Title
- Sustainability Assessment of Wind Energy for Buildings.
- Creator
-
Noori, Mehdi, Tatari, Mehmet, Oloufa, Amr, Nam, Boo Hyun, University of Central Florida
- Abstract / Description
-
Due to increasing concerns for global climate change, onshore and offshore wind energy technologies have stimulated a tremendous interest worldwide, and are considered as a viable solution to mitigate the environmental impacts related to electricity generation. Although wind energy technologies have been considered as one of the cleanest energy sources, they have a wide range of direct and indirect environmental impacts when the whole supply chain is considered. This study aims to quantify...
Show moreDue to increasing concerns for global climate change, onshore and offshore wind energy technologies have stimulated a tremendous interest worldwide, and are considered as a viable solution to mitigate the environmental impacts related to electricity generation. Although wind energy technologies have been considered as one of the cleanest energy sources, they have a wide range of direct and indirect environmental impacts when the whole supply chain is considered. This study aims to quantify the direct and indirect environmental impacts of onshore and offshore wind power technologies by tracing all of the economy-wide supply chain requirements. To accomplish this goal, we developed a comprehensive hybrid life cycle assessment (LCA) model in which process-based LCA model is combined with the economic input-output (EIO) analysis. The analysis results show that on average, concrete and steel and their supply chains are responsible for 37% and 24% of carbon footprint, consequently. On average, offshore wind turbines produce 48% less greenhouse gas emissions per kWh produced electricity than onshore wind turbines. For the onshore wind turbines, concrete, aggregates, and crushed stone approximately consume 95% of total water in this construction phase. On the other hand, concrete, lead, copper, and aggregate are responsible for around 90% of total water for the offshore wind turbines. It is also found that the more capacity the wind turbine has, the less environmental impact the wind turbine generates per kWh electricity. Moreover, based on the economic and environmental impacts of studied wind turbines and also three more nonrenewable energy sources, this study develops a decision making framework to understand the best energy source mix for a building in the state of Florida. This framework accounts for the uncertainty in the input material by deploying a Monte Carlo simulation approach. The results of decision making framework show that natural gas is a better option among nonrenewable sources. On the other hand, V90-3.0 MW offshore wind turbine is the best source of energy among renewable energy sources for a building.The findings of this research are critical for policy makers to understand the direct and indirect environmental impacts of different onshore and offshore wind energy systems. Also this study furnishes the decision maker with a range of possible energy mixes based on different economic and environmental weights.
Show less - Date Issued
- 2013
- Identifier
- CFE0005038, ucf:50017
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005038
- Title
- MAXIMUM ENERGY HARVESTING CONTROL FOROSCILLATING ENERGY HARVESTING SYSTEMS.
- Creator
-
Elmes, John, Batarseh, Issa, University of Central Florida
- Abstract / Description
-
This thesis presents an optimal method of designing and controlling an oscillating energy harvesting system. Many new and emerging energy harvesting systems, such as the energy harvesting backpack and ocean wave energy harvesting, capture energy normally expelled through mechanical interactions. Often the nature of the system indicates slow system time constants and unsteady AC voltages. This paper reveals a method for achieving maximum energy harvesting from such sources with fast...
Show moreThis thesis presents an optimal method of designing and controlling an oscillating energy harvesting system. Many new and emerging energy harvesting systems, such as the energy harvesting backpack and ocean wave energy harvesting, capture energy normally expelled through mechanical interactions. Often the nature of the system indicates slow system time constants and unsteady AC voltages. This paper reveals a method for achieving maximum energy harvesting from such sources with fast determination of the optimal operating condition. An energy harvesting backpack, which captures energy from the interaction between the user and the spring decoupled load, is presented in this paper. The new control strategy, maximum energy harvesting control (MEHC), is developed and applied to the energy harvesting backpack system to evaluate the improvement of the MEHC over the basic maximum power point tracking algorithm.
Show less - Date Issued
- 2007
- Identifier
- CFE0001822, ucf:47345
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001822
- Title
- ANCHORING ENERGY AND PRETILT ANGLE EFFECTS ON LIQUID CRYSTAL RESPONSE TIME.
- Creator
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Nie, Xiangyi, Wu, Shin-Tson, University of Central Florida
- Abstract / Description
-
This dissertation covers some important topics on the liquid crystal-substrate surface effects, including theoretical derivations and confirming experimental results. The research work is expected to make important impacts on liquid crystal device designs and to open new doors for further research along these topics. In this dissertation, a novel high-electric-field technique is developed to characterize the anchoring energy of vertically-aligned liquid crystal cells. Both theoretical...
Show moreThis dissertation covers some important topics on the liquid crystal-substrate surface effects, including theoretical derivations and confirming experimental results. The research work is expected to make important impacts on liquid crystal device designs and to open new doors for further research along these topics. In this dissertation, a novel high-electric-field technique is developed to characterize the anchoring energy of vertically-aligned liquid crystal cells. Both theoretical analyses and confirming experimental results are presented. Vertically-aligned liquid crystal cells with buffed polyimide alignment layers are used to validate the measurement techniques. Based on the voltage-dependent transmittance of the liquid crystal cells, a linear fitting can be obtained, which leads to a precise determination of the anchoring energy. If some specific liquid crystal material parameters are known, then the traditional cell capacitance measurements can be avoided. Anchoring energy and cell gap effects on liquid crystal response time is theoretically analyzed and experimentally investigated. A novel theory on the liquid crystal dynamics is developed. In this part, two different theoretical approaches are discussed: one is surface dynamic equation method and the other is effective cell gap method. These two different approaches lead to consistent results, which are also confirmed by our experimental results. This work opens a new door for LCD industry to optimize liquid crystal response time, and it is especially critical for liquid crystal cells with thin cell gap, which is a promising approach for fast response time liquid crystal display. Pretilt angle effects on liquid crystal dynamics are analyzed theoretically and validated experimentally. Analytical expressions are derived to describe liquid crystal response time under nonzero pretilt angle conditions. The theoretical analysis is confirmed experimentally using vertically-aligned liquid crystal cells. These results quantitatively correlate pretilt angles with liquid crystal response time, which is important for optimizing liquid crystal response time.
Show less - Date Issued
- 2007
- Identifier
- CFE0001927, ucf:47440
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001927
- Title
- ANATOMICAL AND FUNCTIONAL ASSESSMENT OF PNMT+ NEURONS IN THE MOUSE HYPOTHALAMUS AND CEREBELLUM: POTENTIAL ROLES IN ENERGY METABOLISM AND MOTOR CONTROL.
- Creator
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Lindo, Lake A, Ebert, Steven, University of Central Florida
- Abstract / Description
-
Phenylethanolamine N-methyltransferase (Pnmt) is the enzyme in the catecholamine pathway responsible for converting norepinephrine to epinephrine. Pnmt is present in numerous areas; however, the scope of its expression in the mouse brain is not fully understood. A genetic mouse model was generated by the Ebert lab that exhibited the selective destruction of all Pnmt+ cells through the induction of apoptosis by Diphtheria Toxin A. Unexpected phenotypic defects arose that are characterized by...
Show morePhenylethanolamine N-methyltransferase (Pnmt) is the enzyme in the catecholamine pathway responsible for converting norepinephrine to epinephrine. Pnmt is present in numerous areas; however, the scope of its expression in the mouse brain is not fully understood. A genetic mouse model was generated by the Ebert lab that exhibited the selective destruction of all Pnmt+ cells through the induction of apoptosis by Diphtheria Toxin A. Unexpected phenotypic defects arose that are characterized by metabolic weight deficits and motor ataxia. The distribution of Pnmt+ neurons was examined throughout the hypothalamus and cerebellum to generate an anatomical map of current and historical Pnmt expression using various histochemical methods. Historical Pnmt expression appears more extensive than current expression levels at the adult stage, indicating that certain cells in the mouse brain may have experienced transient Pnmt expression. The presence of Pnmt in these regions suggests that the destruction of these neurons may play a role in the phenotypic defects observed in the ablation mouse model. Gaining a more comprehensive understanding of the potential role of Pnmt in these areas may elucidate new drug targets or novel methods to treat obesity and motor control disorders such as ataxia.
Show less - Date Issued
- 2018
- Identifier
- CFH2000547, ucf:45689
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000547
- Title
- HEALING HANDS: REVIEWING THE POTENTIAL APPLICATIONS OF ENERGY THERAPIES TO REDIRECT PAIN DURING LABOR AND CHILDBIRTH.
- Creator
-
Dinh, Cecelia, Burr, Joyce, University of Central Florida
- Abstract / Description
-
The birth experience is a highly subjective phenomenon that leaves a lasting impression for mothers and their families and friends. Although the passage of a child from the mother's womb into the world is typically joyous, the experience is not always as positive. Negative physical and psychological factors may greatly impact a woman's impression of the childbirth experience. Among childbearing women, the two main concerns of childbirth are pain and safe management. Similarly among healthcare...
Show moreThe birth experience is a highly subjective phenomenon that leaves a lasting impression for mothers and their families and friends. Although the passage of a child from the mother's womb into the world is typically joyous, the experience is not always as positive. Negative physical and psychological factors may greatly impact a woman's impression of the childbirth experience. Among childbearing women, the two main concerns of childbirth are pain and safe management. Similarly among healthcare providers, management of labor pain is one of the main goals of maternity care. Pain is a highly subjective phenomenon that is expected during the birth experience. Pharmacologic interventions have significantly reduced pain perception, but have left many women dissatisfied with the overall birth experience due to their potential adverse effects. Energy therapies have been studied for their role in creating a positive birth experience in relation to pain. This literature review examines the empirical evidence and makes suggestions for research and practice regarding energy therapies during labor and childbirth published between 1986 and 2012. Energy therapies, specifically Reiki, Therapeutic touch (TT), and Healing touch (HT) were examined in regards to pain perception and the childbirth process. Although pharmacologic interventions have been successful in reducing some childbirth concerns, the addition of complementary therapies such as Reiki, TT, and/or HT provides a holistic approach to pain management during labor and childbirth.
Show less - Date Issued
- 2012
- Identifier
- CFH0004246, ucf:44962
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004246
- Title
- STUDY OF FILM COOLING EFFECTIVENESS: CONICAL, TRENCHED AND ASYMMETRICAL SHAPED HOLES.
- Creator
-
Zuniga, Humberto, Kapat, Jayanta, University of Central Florida
- Abstract / Description
-
Film cooling is a technique whereby air from the compressor stage of a gas turbine engine is diverted for cooling purposes to parts, such as the turbine stage, that operate at very high temperatures. Cooling arrangements include impingement jets, finned, ribbed and turbulated channels, and rows of film cooling holes, all of which over the years have become progressively more complex. This costly, but necessary complexity is a result of the industry's push to run engines at increasingly higher...
Show moreFilm cooling is a technique whereby air from the compressor stage of a gas turbine engine is diverted for cooling purposes to parts, such as the turbine stage, that operate at very high temperatures. Cooling arrangements include impingement jets, finned, ribbed and turbulated channels, and rows of film cooling holes, all of which over the years have become progressively more complex. This costly, but necessary complexity is a result of the industry's push to run engines at increasingly higher turbine inlet temperatures. Higher temperatures mean higher efficiency, but they also mean that the turbine first stage operates hundreds of degrees Kelvin above the melting point of the metal core of the vanes and blades. Existing cooling technology and materials make it possible to protect these parts and allow them to function for extended periods of time--but this comes at a price: the compressed air that is used for cooling represents a considerable penalty in overall turbine efficiency. The aim of current cooling research is threefold: to improve the protection of components from extreme fluxes in order to extend the life of the parts; to increase the inlet turbine operating temperature; and to reduce the amount of air that is diverted from the compressor for cooling. Current film cooling schemes consist of forcing air through carefully machined holes on a part and ejecting it at an angle with the intent of cooling that part by blanketing the surface downstream of the point of ejection. The last major development in the field has been the use of expanded hole exits, which reduce coolant momentum and allow for greater surface coverage. Researchers and designers are continuously looking for novel geometries and arrangements that would increase the level of protection or maintain it while using less coolant. This dissertation investigates such novel methods which one day may include combinations of cylindrical and fan-shaped holes embedded inside trenches, conical holes, or even rows of asymmetric fan-shaped holes. The review of current literature reveals that very few investigations have been done on film cooling effectiveness for uniformly diffusing conical holes. They have been treated as a sort of side novelty since industrial partners often say they are hard to manufacture. To extend our understanding of effectiveness of conical holes, the present study investigates the effect of increasing diffusion angle, as well as the effect of adding a cylindrical entrance length to a conical hole. The measurements were made in the form of film cooling effectiveness and the technique used was temperature sensitive paint. Eight different conical geometries were tested in the form of coupons with rows of holes. The geometry of the holes changed from pure cylindrical holes, a 0° cylindrical baseline, to an 8° pure cone. The coupons were tested in a closed loop wind tunnel at blowing ratios varying from 0.5 to 1.5, and the coolant employed was nitrogen gas. Results indicate that the larger conical holes do, in fact offer appropriate protection and that the holes with the higher expansion angles perform similar to fan-shaped baseline holes, even at the higher blower ratios. The study was also extended to two other plates in which the conical hole was preceded by a cylindrical entry length. The performance of the conical holes improves as a result of the entry length and this is seen at the higher blowing ratios in the form of a delay in the onset of jet detachment. The results of this study show that conical expanding holes are a viable geometry and that their manufacturing can be made easier with a cylindrical entry length, at the same time improving the performance of these holes. Trench cooling consists of having film cooling holes embedded inside a gap, commonly called a trench. The walls of this gap are commonly vertical with respect to the direction of the main flow and are directly in the path of the coolant. The coolant hits the downstream trench wall which forces it to spread laterally, resulting in more even film coverage downstream than that of regular holes flush with the surface. Recent literature has focused on the effect that trenching has on cylindrical cooling holes only. While the results indicate that trenches are an exciting, promising new geometry derived from the refurbishing process of thermal barrier ceramic coatings, not all the parameters affecting film cooling have been investigated relating to trenched holes. For example, nothing has been said about how far apart holes inside the trench will need to be placed for them to stop interacting. Nothing has been said about shaped holes inside a trench, either. This dissertation explores the extent to which trenching is useful by expanding the PI/D from 4 to 12 for rows of round and fan holes. In addition the effect that trenching has on fan-shaped holes is studied by systematically increasing the trench depth. Values of local, laterally-averaged and spatially-averaged film cooling effectiveness are reported. It is found that placing the cylinders inside the trench and doubling the distance between the holes provides better performance than the cylindrical, non-trenched baseline, especially at the higher blowing ratios, M > 1.0. At these higher coolant flow rates, the regular cylindrical jets show detachment, while those in the trench do not. They, in fact perform very well. The importance of this finding implies that the number of holes, and coolant, can be cut in half while still improving performance over regular holes. The trenched cylindrical holes did not, however, perform like the fan shaped holes. It was found that the performance of fan-shaped holes inside trenches is actually diminished by the presence of the trench. It is obvious, since the fan diffuses the flow, reducing the momentum of the coolant; the addition of the trench further slows the flow down. This, in turn, leads to the quicker ingestion of the main flow by the jets resulting in lower effectiveness. The next part of the study consisted of systematically increasing the depth of the trench for the fan-shaped holes. The purpose of this was to quantify the effect of the trench on the film cooling effectiveness. It was found that the presence of the trench significantly reduces the film effectiveness, especially for the deeper cases. At the higher blowing ratios, the overall performance of the fans collapses to the same value signifying insensitivity to the blowing ratio. A recent study suggests that having a compound angle could reduce the protective effect of the film due to the elevated interaction between the non-co-flowing coolant jet and the mainstream. Although it has been suggested that a non-symmetric lateral diffusion could mitigate the ill effects of having a compound angle, little has been understood on the effect this non-symmetry has on film cooling effectiveness. The last part of this study investigates the effect of non-symmetric lateral diffusion on film cooling effectiveness by systematically varying one side of a fan-shaped hole. For this part of the study, one of the lateral angles of diffusion of a fan-shaped hole was changed from 5° to 13°, while the other side was kept at 7°. It was found that a lower angle of diffusion hurts performance, while a larger diffusion angle improves it. However, the more significant result was that the jet seemed to be slightly turning. This suggests that the jets actually have two regions: one region with reduced momentum, ideal for protecting a large area downstream of the point of injection; and another region with more integrity which could withstand more aggressive main flow conditions. A further study should be conducted for this geometry at compound angles with the main flow to test this theory. The studies conducted show that the temperature sensitive paint technique can be used to study the performance of film cooling holes for various geometries. The studies also show the film cooling performance of novel geometries and explain why, in some cases, such new arrangements are desirable, and in others, how they can hurt performance. The studies also point in the direction of further investigations in order to advance cooling technology to more effective applications and reduced coolant consumption, the main goal of applied turbine cooling research.
Show less - Date Issued
- 2009
- Identifier
- CFE0002831, ucf:48082
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002831
- Title
- Developing new power management and High-Reliability Schemes in Data-Intensive Environment.
- Creator
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Wang, Ruijun, Wang, Jun, Jin, Yier, DeMara, Ronald, Zhang, Shaojie, Ni, Liqiang, University of Central Florida
- Abstract / Description
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With the increasing popularity of data-intensive applications as well as the large-scale computingand storage systems, current data centers and supercomputers are often dealing with extremelylarge data-sets. To store and process this huge amount of data reliably and energy-efficiently,three major challenges should be taken into consideration for the system designers. Firstly, power conservation(-)Multicore processors or CMPs have become a mainstream in the current processormarket because of...
Show moreWith the increasing popularity of data-intensive applications as well as the large-scale computingand storage systems, current data centers and supercomputers are often dealing with extremelylarge data-sets. To store and process this huge amount of data reliably and energy-efficiently,three major challenges should be taken into consideration for the system designers. Firstly, power conservation(-)Multicore processors or CMPs have become a mainstream in the current processormarket because of the tremendous improvement in transistor density and the advancement in semiconductor technology. However, the increasing number of transistors on a single die or chip reveals a super-linear growth in power consumption [4]. Thus, how to balance system performance andpower-saving is a critical issue which needs to be solved effectively. Secondly, system reliability(-)Reliability is a critical metric in the design and development of replication-based big data storagesystems such as Hadoop File System (HDFS). In the system with thousands machines and storagedevices, even in-frequent failures become likely. In Google File System, the annual disk failurerate is 2:88%,which means you were expected to see 8,760 disk failures in a year. Unfortunately,given an increasing number of node failures, how often a cluster starts losing data when beingscaled out is not well investigated. Thirdly, energy efficiency(-)The fast processing speeds of the current generation of supercomputers provide a great convenience to scientists dealing with extremely large data sets. The next generation of (")exascale(") supercomputers could provide accuratesimulation results for the automobile industry, aerospace industry, and even nuclear fusion reactors for the very first time. However, the energy cost of super-computing is extremely high, with a total electricity bill of 9 million dollars per year. Thus, conserving energy and increasing the energy efficiency of supercomputers has become critical in recent years.This dissertation proposes new solutions to address the above three key challenges for currentlarge-scale storage and computing systems. Firstly, we propose a novel power management scheme called MAR (model-free, adaptive, rule-based) in multiprocessor systems to minimize the CPU power consumption subject to performance constraints. By introducing new I/O wait status, MAR is able to accurately describe the relationship between core frequencies, performance and power consumption. Moreover, we adopt a model-free control method to filter out the I/O wait status from the traditional CPU busy/idle model in order to achieve fast responsiveness to burst situations and take full advantage of power saving. Our extensive experiments on a physical testbed demonstrate that, for SPEC benchmarks and data-intensive (TPC-C) benchmarks, an MAR prototype system achieves 95.8-97.8% accuracy of the ideal power saving strategy calculated offline. Compared with baseline solutions, MAR is able to save 12.3-16.1% more power while maintain a comparable performance loss of about 0.78-1.08%. In addition, more simulation results indicate that our design achieved 3.35-14.2% more power saving efficiency and 4.2-10.7% less performance loss under various CMP configurations as compared with various baseline approaches such as LAST, Relax,PID and MPC.Secondly, we create a new reliability model by incorporating the probability of replica loss toinvestigate the system reliability of multi-way declustering data layouts and analyze their potential parallel recovery possibilities. Our comprehensive simulation results on Matlab and SHARPE show that the shifted declustering data layout outperforms the random declustering layout in a multi-way replication scale-out architecture, in terms of data loss probability and system reliability by upto 63% and 85% respectively. Our study on both 5-year and 10-year system reliability equipped with various recovery bandwidth settings shows that, the shifted declustering layout surpasses the two baseline approaches in both cases by consuming up to 79 % and 87% less recovery bandwidth for copyset, as well as 4.8% and 10.2% less recovery bandwidth for random layout.Thirdly, we develop a power-aware job scheduler by applying a rule based control method and takinginto account real world power and speedup profiles to improve power efficiency while adheringto predetermined power constraints. The intensive simulation results shown that our proposed method is able to achieve the maximum utilization of computing resources as compared to baselinescheduling algorithms while keeping the energy cost under the threshold. Moreover, by introducinga Power Performance Factor (PPF) based on the real world power and speedup profiles, we areable to increase the power efficiency by up to 75%.
Show less - Date Issued
- 2016
- Identifier
- CFE0006704, ucf:51907
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006704
- Title
- Polyelectrolyte complexes based on poly(acrylic acid): mechanics and applications.
- Creator
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Lu, Xiaoyan, Zhai, Lei, Zou, Shengli, Chumbimuni Torres, Karin, Kolpashchikov, Dmitry, Dong, Yajie, University of Central Florida
- Abstract / Description
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Poly(acrylic acid) (PAA) is a weak polyelectrolyte presenting negative charge at basic conditionwhen the carboxylic group loses a proton. These carboxylate group can interact with polycationsand metal ions to form stable polyelectrolyte complexes (PECs), leading to tunable propertiesand multifunctional nanoscale structures through chemical reactions. This research focuses onnanofiber and nanoparticle fabricated by PAA-based PECs. We demonstrated the effect of ferricion concentration on the...
Show morePoly(acrylic acid) (PAA) is a weak polyelectrolyte presenting negative charge at basic conditionwhen the carboxylic group loses a proton. These carboxylate group can interact with polycationsand metal ions to form stable polyelectrolyte complexes (PECs), leading to tunable propertiesand multifunctional nanoscale structures through chemical reactions. This research focuses onnanofiber and nanoparticle fabricated by PAA-based PECs. We demonstrated the effect of ferricion concentration on the mechanical properties of PAA-based single naonofiber by using dark fieldmicroscopy imaging and persistence length analysis. The application of PAA-based nanofibermats loaded with MnO2 for supercapacitors was also explored. As a free-standing and flexiblesupercapacitor electrode, the nanofiber mat exhibited outstanding properties including high specificcapacitance, excellent reversible redox reactions, and fast charge/discharge ability. Since PAA is abiocompatible polymer, PAA-based PEC was applied as a drug-carrier in a drug delivery system.In this project, core-shell nanoparticles were fabricated with chitosan as the core and PAA as theshell to incorporate with the drug gemcitabine. Several parameters were investigated to obtainthe optimal nanoparticle size. The as-prepared drug delivery system shows prolonged releasingprofile.
Show less - Date Issued
- 2018
- Identifier
- CFE0007045, ucf:52004
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007045
- Title
- A Comprehensive Assessment of Vehicle-to-Grid Systems and Their Impact to the Sustainability of Current Energy and Water Nexus.
- Creator
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Zhao, Yang, Tatari, Omer, Oloufa, Amr, Mayo, Talea, Zheng, Qipeng, University of Central Florida
- Abstract / Description
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This dissertation aims to explore the feasibility of incorporating electric vehicles into the electric power grid and develop a comprehensive assessment framework to predict and evaluate the life cycle environmental, economic and social impact of the integration of Vehicle-to-Grid systems and the transportation-water-energy nexus. Based on the fact that electric vehicles of different classes have been widely adopted by both fleet operators and individual car owners, the following questions...
Show moreThis dissertation aims to explore the feasibility of incorporating electric vehicles into the electric power grid and develop a comprehensive assessment framework to predict and evaluate the life cycle environmental, economic and social impact of the integration of Vehicle-to-Grid systems and the transportation-water-energy nexus. Based on the fact that electric vehicles of different classes have been widely adopted by both fleet operators and individual car owners, the following questions are investigated: 1. Will the life cycle environmental impacts due to vehicle operation be reduced? 2. Will the implementation of Vehicle-to-Grid systems bring environmental and economic benefits? 3. Will there be any form of air emission impact if large amounts of electric vehicles are adopted in a short time? 4. What is the role of the Vehicle-to-Grid system in the transportation-water-energy nexus? To answer these questions: First, the life cycle environmental impacts of medium-duty trucks in commercial delivery fleets are analyzed. Second, the operation mechanism of Vehicle-to-Grid technologies in association with charging and discharging of electric vehicles is researched. Third, the feasible Vehicle-to-Grid system is further studied taking into consideration the spatial and temporal variance as well as other uncertainties within the system. Then, a comparison of greenhouse gas emission mitigation of the Vehicle-to-Grid system and the additional emissions caused by electric vehicle charging through marginal electricity is analyzed. Finally, the impact of the Vehicle-to-Grid system in the transportation-water-energy nexus, and the underlying environmental, economic and social relationships are simulated through system dynamic modeling. The results provide holistic evaluations and spatial and temporal projections of electric vehicles, Vehicle-to-Grid systems, wind power integration, and the transportation-water-energy nexus.
Show less - Date Issued
- 2017
- Identifier
- CFE0007300, ucf:52153
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007300
- Title
- Nanoscale Spectroscopy in Energy and Catalytic Applications.
- Creator
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Ding, Yi, Tetard, Laurene, Challapalli, Suryanarayana, Zhai, Lei, Thomas, Jayan, Lyakh, Arkadiy, Blair, Richard, University of Central Florida
- Abstract / Description
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Emerging societal challenges such as the need for more sustainable energy and catalysis are requiring more sensitive and versatile measurements at the nanoscale. This is the case in the design and optimization of new materials for energy harvesting (solar cells) and energy storage devices (batteries and capacitors), or for the development of new catalysts for carbon sequestration or other reactions of interest. Hence, the ability to advance spectroscopy with nanoscale spatial resolution and...
Show moreEmerging societal challenges such as the need for more sustainable energy and catalysis are requiring more sensitive and versatile measurements at the nanoscale. This is the case in the design and optimization of new materials for energy harvesting (solar cells) and energy storage devices (batteries and capacitors), or for the development of new catalysts for carbon sequestration or other reactions of interest. Hence, the ability to advance spectroscopy with nanoscale spatial resolution and high sensitivity holds great promises to meet the demands of deeper fundamental understanding to boost the development and deployment of nano-based devices for real applications. In this dissertation, the impact of nanoscale characterization on energy-related and catalytic materials is considered. Firstly an introduction of the current energy and environmental challenges and our motivations are presented. We discuss how revealing nanoscale properties of solar cell active layers and supercapacitor electrodes can greatly benefit the performance of devices, and ponder on the advantages over conventional characterization techniques. Next, we focus on two dimensional materials as promising alternative catalysts to replace conventional noble metals for carbon sequestration and its conversion to added-value products. Defect-laden hexagonal boron nitride (h-BN) has been identified as a good catalyst candidate for carbon sequestration. Theoretically, defects exhibit favorable properties as reaction sites. However, the detailed mechanism pathways cannot be readily probed experimentally, due to the lack of tools with sufficient sensitivity and time resolution. A comprehensive study of the design and material processes used to introduce defects in h-BN in view of improving the catalytic properties is presented. The processing-structure-property relationships are investigated using a combination of conventional characterization and advanced nanoscale techniques. In addition to identifying favorable conditions for defect creation, we also report on the first signs of local reactions at defect sites obtained with nanoscale spectroscopy. Next, we explore avenues to improve the sensitivity and time-resolution of nanoscale measurements using light-assisted AFM-based nanomechanical spectroscopy. For each configuration, we evaluate the new system by comparing its performance to the commercial capabilities.Lastly, we provide a perspective on the opportunities for state-of-the-art characterization to impact the fields of catalysis and sustainable energy, as well as the urge for highly sensitive functional capabilities and time-resolution for nanoscale studies.
Show less - Date Issued
- 2018
- Identifier
- CFE0007751, ucf:52387
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007751
- Title
- Examining Work-To-Rest Ratios To Optimize Upper Body Sprint Interval Training.
- Creator
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Lamonica, Michael, Fukuda, David, Hoffman, Jay, Stout, Jeffrey, Fragala, Maren, University of Central Florida
- Abstract / Description
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The primary purpose of this study was to compare the metabolic influence of varying work-to-rest ratios during upper body sprint interval training (SIT). Forty-two recreationally trained men were randomized into one of three training groups [10s work bouts with two minutes of rest (10:2, n = 11) or four minutes of rest (10:4, n = 11), or 30s work bouts with four minutes of rest (30:4, n = 10)] or a control group (CON, n = 10). Participants underwent six training sessions over two weeks with...
Show moreThe primary purpose of this study was to compare the metabolic influence of varying work-to-rest ratios during upper body sprint interval training (SIT). Forty-two recreationally trained men were randomized into one of three training groups [10s work bouts with two minutes of rest (10:2, n = 11) or four minutes of rest (10:4, n = 11), or 30s work bouts with four minutes of rest (30:4, n = 10)] or a control group (CON, n = 10). Participants underwent six training sessions over two weeks with four to six 'all-out' sprints. During pre- and post-intervention visits, participants underwent a graded exercise test to determine maximal oxygen consumption (V?O2peak) and peak power output (PPO), four constant-work rate trials to determine critical power (CP), anaerobic working capacity (W'), and electromyographic fatigue threshold (EMGFT), and an upper body Wingate test to determine peak power (PP), mean power (MP), and total work (TW). Oxygen consumption and blood lactate during the Wingate test generated estimates of oxidative, glycolytic, and ATP-PCr energy system provisions. An analysis of covariance was performed on all testing measurements collected at post with the associated pre-values used as covariates. V?O2peak was greater in 30:4 (p = .007) and 10:2 (p = .036) compared to CON and PPO was greater in 30:4 than CON (p = .007). No differences were observed between groups in CP (p = .530), W' (p = .900), EMGFT (p = .692), PP (p = .692), MP (p = .290), or TW (p = .291). Relative energy contribution (p = .026) and energy expenditure (p = .019) of the ATP-PCr energy system was greater in 10:4 compared to CON. SIT protocols with larger work-to-rest ratios induce enhanced aerobic adaptions, whereas smaller work-to-rest ratios may enhance ATP-PCr utilization in the upper body over a short-term two-week intervention.
Show less - Date Issued
- 2018
- Identifier
- CFE0007036, ucf:51978
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007036
- Title
- CFD Analysis of a Uni-directional Impulse Turbine for Wave Energy Conversion.
- Creator
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Velez, Carlos, Ilie, Marcel, Lin, Kuo-Chi, Qu, Zhihua, University of Central Florida
- Abstract / Description
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Ocean energy research has grown in popularity in the past decade and has producedvarious designs for wave energy extraction. This thesis focuses on the performance analysis of auni-directional impulse turbine for wave energy conversion. Uni-directional impulse turbines canproduce uni-directional rotation in bi-directional flow, which makes it ideal for wave energyextraction as the motion of ocean waves are inherently bi-directional. This impulse turbine iscurrently in use in four of the world...
Show moreOcean energy research has grown in popularity in the past decade and has producedvarious designs for wave energy extraction. This thesis focuses on the performance analysis of auni-directional impulse turbine for wave energy conversion. Uni-directional impulse turbines canproduce uni-directional rotation in bi-directional flow, which makes it ideal for wave energyextraction as the motion of ocean waves are inherently bi-directional. This impulse turbine iscurrently in use in four of the world's Oscillating Wave Columns (OWC). Current research todate has documented the performance of the turbine but little research has been completed tounderstand the flow physics in the turbine channel. An analytical model and computational fluiddynamic simulations are used with reference to experimental results found in the literature todevelop accurate models of the turbine performance. To carry out the numerical computationsvarious turbulence models are employed and compared. The comparisons indicate that a lowReynolds number Yang-shih K-Epsilon turbulence model is the most computationally efficientwhile providing accurate results. Additionally, analyses of the losses in the turbine are isolatedand documented.Results indicate that large separation regions occur on the turbine blades whichdrastically affect the torque created by the turbine, the location of flow separation is documentedand compared among various flow regimes. The model and simulations show good agreementwith the experimental results and the two proposed solutions enhance the performance of theturbine showing an approximate 10% increase in efficiency based on simulation results.
Show less - Date Issued
- 2011
- Identifier
- CFE0004173, ucf:49049
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004173
- Title
- ESTABLISHING DEGRADATION RATES AND SERVICE LIFETIME OF PHOTOVOLTAIC SYSTEMS.
- Creator
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Leyte-Vidal, Albert, Hickman, James, University of Central Florida
- Abstract / Description
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As fossil fuel sources continue to diminish, oil prices continue to increase, and global warming and CO2 emissions keep impacting the environment, it has been necessary to shift energy consumption and generation to a different path. Solar energy has proven to be one of the most promising sources of renewable energy because it is environmentally friendly, available anywhere in the world, and cost competitive. For photovoltaic (PV) system engineers, designing a PV system is not an easy task....
Show moreAs fossil fuel sources continue to diminish, oil prices continue to increase, and global warming and CO2 emissions keep impacting the environment, it has been necessary to shift energy consumption and generation to a different path. Solar energy has proven to be one of the most promising sources of renewable energy because it is environmentally friendly, available anywhere in the world, and cost competitive. For photovoltaic (PV) system engineers, designing a PV system is not an easy task. Research demonstrates that different PV technologies behave differently under certain conditions; therefore energy production varies not only with capacity of the system but also with the type of module. For years, researchers have also studied how these different technologies perform for long periods of time, when exposed out in the field. In this study, data collected by the Florida Solar Energy Center for periods of over four years was analyzed using two techniques, widely accepted by researchers and industry, to evaluate the long‐term performance of five systems. The performance ratio analysis normalizes system capacity and enables the comparison of performance between multiple systems. In PVUSA Regression analysis, regression coefficients are calculated which correspond to the effect of irradiance, wind speed, and ambient temperature, and these coefficients are then used to calculate power at a predetermined set of conditions. This study allows manufacturers to address the difficulties found on system lifetime when their modules are installed out on the field. Also allows for the further development and improvement of the different PV technologies already commercially available.
Show less - Date Issued
- 2010
- Identifier
- CFE0003326, ucf:48483
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003326
