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A Comprehensive Assessment of Vehicle-to-Grid Systems and Their Impact to the Sustainability of Current Energy and Water Nexus
Title
A Comprehensive Assessment of Vehicle-to-Grid Systems and Their Impact to the Sustainability of Current Energy and Water Nexus.
Creator
Zhao, Yang, Tatari, Omer, Oloufa, Amr, Mayo, Talea, Zheng, Qipeng, University of Central Florida
Abstract / Description
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.
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Date Issued
2017
Identifier
CFE0007300, ucf:52153
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007300
AN INVERSE ALGORITHM TO ESTIMATE THERMAL CONTACT RESISTANCE
Title
AN INVERSE ALGORITHM TO ESTIMATE THERMAL CONTACT RESISTANCE.
Creator
Gill, Jennifer, Kassab, Alain, University of Central Florida
Abstract / Description
Thermal systems often feature composite regions that are mechanically mated. In general, there exists a significant temperature drop across the interface between such regions which may be composed of similar or different materials. The parameter characterizing this temperature drop is the thermal contact resistance, which is defined as the ratio of the temperature drop to the heat flux normal to the interface. The thermal contact resistance is due to roughness effects between mating surfaces...
Show moreThermal systems often feature composite regions that are mechanically mated. In general, there exists a significant temperature drop across the interface between such regions which may be composed of similar or different materials. The parameter characterizing this temperature drop is the thermal contact resistance, which is defined as the ratio of the temperature drop to the heat flux normal to the interface. The thermal contact resistance is due to roughness effects between mating surfaces which cause certain regions of the mating surfaces to loose contact thereby creating gaps. In these gap regions, the principal modes of heat transfer are conduction across the contacting regions of the interface, conduction or natural convection in the fluid filling the gap regions of the interface, and radiation across the gap surfaces. Moreover, the contact resistance is a function of contact pressure as this can significantly alter the topology of the contact region. The thermal contact resistance is a phenomenologically complex function and can significantly alter prediction of thermal models of complex multi-component structures. Accurate estimates of thermal contact resistances are important in engineering calculations and find application in thermal analysis ranging from relatively simple layered and composite materials to more complex biomaterials. There have been many studies devoted to the theoretical predictions of thermal contact resistance and although general theories have been somewhat successful in predicting thermal contact resistances, most reliable results have been obtained experimentally. This is due to the fact that the nature of thermal contact resistance is quite complex and depends on many parameters including types of mating materials, surface characteristics of the interfacial region such as roughness and hardness, and contact pressure distribution. In experiments, temperatures are measured at a certain number of locations, usually close to the contact surface, and these measurements are used as inputs to a parameter estimation procedure to arrive at the sought-after thermal contact resistance. Most studies seek a single value for the contact resistance, while the resistance may in fact also vary spatially. In this thesis, an inverse problem (IP) is formulated to estimate the spatial variation of the thermal contact resistance along an interface in a two-dimensional configuration. Temperatures measured at discrete locations using embedded sensors appropriately placed in proximity to the interface provide the additional information required to solve the inverse problem. A superposition method serves to determine sensitivity coefficients and provides guidance in the location of the measuring points. Temperature measurements are then used to define a regularized quadratic functional that is minimized to yield the contact resistance between the two mating surfaces. A boundary element method analysis (BEM) provides the temperature field under current estimates of the contact resistance in the solution of the inverse problem when the geometry of interest is not regular, while an analytical solution can be used for regular geometries. Minimization of the IP functional is carried out by the Levenberg-Marquadt method or by a Genetic Algorithm depending on the problem under consideration. The L-curve method of Hansen is used to choose the optimal regularization parameter. A series of numerical examples are provided to demonstrate and validate the approach.
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Date Issued
2005
Identifier
CFE0000748, ucf:46582
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000748
STRUCTURAL CONDITION ASSESSMENT OF PRESTRESSED CONCRETE TRANSIT GUIDEWAYS
Title
STRUCTURAL CONDITION ASSESSMENT OF PRESTRESSED CONCRETE TRANSIT GUIDEWAYS.
Creator
Shmerling, Robert, Catbas, F. Necati, University of Central Florida
Abstract / Description
Objective condition assessment is essential to make better decisions for safety and serviceability of existing civil infrastructure systems. This study explores the condition of an existing transit guideway system that has been in service for thirty-five years. The structural system is composed of six-span continuous prestressed concrete bridge segments. The overall transit system incorporates a number of continuous bridges which share common design details, geometries, and loading conditions...
Show moreObjective condition assessment is essential to make better decisions for safety and serviceability of existing civil infrastructure systems. This study explores the condition of an existing transit guideway system that has been in service for thirty-five years. The structural system is composed of six-span continuous prestressed concrete bridge segments. The overall transit system incorporates a number of continuous bridges which share common design details, geometries, and loading conditions. The original analysis is based on certain simplifying assumptions such as rigid behavior over supports and simplified tendon/concrete/steel plate interaction. The current objective is to conduct a representative study for a more accurate understanding of the structural system and its behavior. The scope of the study is to generate finite element models (FEMs) to be used in static and dynamic parameter sensitivity studies, as well load rating and reliability analysis of the structure. The FEMs are used for eigenvalue analysis and simulations. Parameter sensitivity studies consider the effect of changing critical parameters, including material properties, prestress loss, and boundary and continuity conditions, on the static and dynamic structural response. Load ratings are developed using an American Association for State Highway Transportation Officials Load and Resistance Factor Rating (AASHTO LRFR) approach. The reliability of the structural system is evaluated based on the data obtained from various finite element models. Recommendations for experimental validation of the FEM are presented. This study is expected to provide information to make better decisions for operations, maintenance and safety requirements; to be a benchmark for future studies, to establish a procedure and methodology for structural condition assessment, and to contribute to the general research body of knowledge in condition assessment and structural health monitoring.
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Date Issued
2005
Identifier
CFE0000658, ucf:46520
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000658
PERCEIVED SERVICE QUALITY'S IMPACT ON BEHAVIORAL INTENTIONS IN THE TIMESHARE INDUSTRY
Title
PERCEIVED SERVICE QUALITY'S IMPACT ON BEHAVIORAL INTENTIONS IN THE TIMESHARE INDUSTRY.
Creator
Pollard, Leonard, Malone, Linda, University of Central Florida
Abstract / Description
This study created a model using factor analysis and structural equation modeling to investigate the relationship of service quality, word-of-mouth recommendation and price sensitivity of individuals who experienced a timeshare mini vacation at a branded timeshare resort. The constructs of service quality were developed by creating a survey tool. A total of 4,797 surveys were electronically sent resulting in a total of 1,275 of the individuals surveyed who met the criteria of staying at a...
Show moreThis study created a model using factor analysis and structural equation modeling to investigate the relationship of service quality, word-of-mouth recommendation and price sensitivity of individuals who experienced a timeshare mini vacation at a branded timeshare resort. The constructs of service quality were developed by creating a survey tool. A total of 4,797 surveys were electronically sent resulting in a total of 1,275 of the individuals surveyed who met the criteria of staying at a branded hotel or resort during their mini vacation. Six different variables were created from the ordinal level questions on the survey: Resort Accommodations, Sales Gallery, Sales Presentation, Resort Activities, Resort Staff and Brand Value. These were then used in an exploratory factor analysis to identify latent factors after which structural equation modeling was used to define the relationship between the factors and the independent variables. A total of 44 models were explored and evaluated based on goodness-of-fit metrics. The model that had the best level of fit was a first-order two-factor model. This model was created with an 80% subset and confirmed with a 20% subset of the sample. The factors found represent the Vacation Experience Promise (VEP) and the Vacation Experience Delivery (VED). There was a positive correlation for both VEP and VED with word-of-mouth recommendation and price sensitivity. The research also posited 24 hypotheses of the relationship between the service quality constructs, word-of-mouth recommendation and price sensitivity with the demographic characteristics of guest type, gender, stay type, age, marital status, gross income, timeshare ownership and the number of presentations attended. There was not enough information to support a relationship between the service quality constructs, word-of-mouth recommendation and price sensitivity with regards to gender, gross income and marital status. There was a difference in the scores for the service quality constructs and the varying categories within the age, stay type, and timeshare ownership demographic variables. There was a difference only in the VED scores and the varying categories within the guest type and presentations attended demographic variables. There was also a difference in the scores for the word-of-mouth recommendation construct and the varying categories within the age, guest type, timeshare ownership and number of presentations attended demographic variables. Lastly, there was also a difference in the scores for the price sensitivity construct and the varying categories within the guest type, timeshare ownership and presentation attended demographic variables. The research discusses the business implications associated with these findings and proposes next steps for future research.
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Date Issued
2010
Identifier
CFE0003475, ucf:48942
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003475