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Title: Business in the Estuary, Party in the Sea: Migration Patterns of Striped Mullet (Mugil cephalus) Within the Indian River Lagoon Complex.
Creator: Myers, Olivia, Cook, Geoffrey, Mansfield, Kate, Reyier, Eric, University of Central Florida
Abstract / Description: Commercial and recreational environmental enterprises in the Indian River Lagoon (IRL), Florida supply nearly 10,000 jobs and produce $1.6 billion dollars a year in revenue. These waters contain iconic species of sportfish, including red drum, snook, and sea trout, as well as their lower trophic level prey such as snapper and mullet. Striped mullet (Mugil cephalus) are both commercially valuable as well as an indicator species for overall ecosystem health. From September to December, mullet...
Show moreCommercial and recreational environmental enterprises in the Indian River Lagoon (IRL), Florida supply nearly 10,000 jobs and produce $1.6 billion dollars a year in revenue. These waters contain iconic species of sportfish, including red drum, snook, and sea trout, as well as their lower trophic level prey such as snapper and mullet. Striped mullet (Mugil cephalus) are both commercially valuable as well as an indicator species for overall ecosystem health. From September to December, mullet in the IRL undergo an annual migration from their inshore foraging habitats to oceanic spawning sites. However, their actual migratory pathways remain unknown. To address this knowledge gap, I utilized passive acoustic telemetry to assess the migration patterns of M. cephalus within the IRL complex, particularly focusing on movement pathways from inshore aggregation sites to oceanic inlets to spawn. Coupling environmental metrics with movement data, I evaluated catalysts for migration as well as travel routes through the estuary. Network analyses identified potential conservation areas of interest and sites needing management intervention. Impoundments around the Merritt Island National Wildlife Refuge appear to serve as an important refuge area for striped mullet while the Banana and Indian Rivers act as corridors during their inshore migratory movements. The environmental metrics of depth, temperature, dissolved oxygen, pH, barometric pressure, and photoperiod were the best predictors for the number of detections and residency time produced by two case studies of striped mullet activity. An emphasis on spatial fisheries management along with vigilant environmental monitoring will ensure the status of this species, to the benefit of both natural and human systems in the Indian River Lagoon. The knowledge generated as a result of this project may also provide a framework for sustainably managing other migratory baitfish.
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Date Issued: 2019
Identifier: CFE0007895, ucf:52768
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007895

Title: Spatial distribution and abundance of large green turtles on foraging grounds in the Florida Keys, USA.
Creator: Welsh, Ryan, Mansfield, Kate, Quintana-Ascencio, Pedro, Gorham, Jonathan, University of Central Florida
Abstract / Description: Discerning distribution, density, and abundance of organisms is essential for conservation and management of imperiled species. However, simple counts of sampled individuals are often not adequate to make such estimates, this is especially true for large and highly mobile marine animals. Green turtles (Chelonia mydas) are a highly migratory, long-lived, late-maturing, marine megafauna, that is beginning to recover from severe global population declines. Distance sampling techniques can be...
Show moreDiscerning distribution, density, and abundance of organisms is essential for conservation and management of imperiled species. However, simple counts of sampled individuals are often not adequate to make such estimates, this is especially true for large and highly mobile marine animals. Green turtles (Chelonia mydas) are a highly migratory, long-lived, late-maturing, marine megafauna, that is beginning to recover from severe global population declines. Distance sampling techniques can be used to generate estimates of abundance of green turtles in foraging grounds which have been relatively unstudied in the Northeastern Atlantic basin, filling in important data gaps in a species that is of critical conservation concern. The Quicksands foraging grounds located west of Key West, Florida, USA is used by both sub-adult and adult green turtles. Standardized transects were performed 18 times between 2006 (-) 2018, and using the collected data; abundances, spatial distribution and evidence of spatial segregation were generated through density surface models and null mode analysis. Densities of foraging green turtles rival some of the largest densities known in the world. Spatial segregation of the two size classes is evident on the foraging ground and may be attributed to differing predator detection and avoidance strategies of the size classes Finally, given the high densities of animals found on the foraging grounds and the rise in general population levels of green turtles and drop in population of green turtle predators (i.e. large sharks), concern is raised for the long term sustainably of the Quicksands seagrass pastures.
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Date Issued: 2019
Identifier: CFE0007874, ucf:52767
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007874

Title: Career preparation for interdisciplinary science PhD students: A case study.
Creator: Gordon, Sabrina, Hastings, Sally, Pryor, Burt, Katt, James, University of Central Florida
Abstract / Description: This case study intended to collect and analyze responses from stakeholders of the UCF Modeling and Simulation graduate program regarding the ways in which interdisciplinary (IDS) science PhD students could be prepared for diverse career paths. A mixed methodology study was executed and quantitative survey (N=96) and qualitative interview (N=10) data were collected to address three research questions. Overall, stakeholders for this case study were found to represent the three main career...
Show moreThis case study intended to collect and analyze responses from stakeholders of the UCF Modeling and Simulation graduate program regarding the ways in which interdisciplinary (IDS) science PhD students could be prepared for diverse career paths. A mixed methodology study was executed and quantitative survey (N=96) and qualitative interview (N=10) data were collected to address three research questions. Overall, stakeholders for this case study were found to represent the three main career paths of academia, government, and industry. Survey data were utilized to gauge the level of importance that survey participants perceived for various survey scales and items. The scales that were rated with the highest means were Ethics, Teamwork, and Career Management (M=3.67, SD=.41) and Interdisciplinary Skills (M=3.67, SD=.36), while the lowest mean was reported for the Professional Science Skills scale (M=3.19, SD=.54). Interview data revealed limitations of the historically accepted apprenticeship model to include an emphasis on academia-only career preparation and a lack of standardization regarding highly individualized advisor-student relationships. And finally, survey and interview participants reported that alternative pedagogical methods to prepare IDS science PhD students for diverse career paths should include internships in each career sector, while also presenting the barriers to implementing internships regarding faculty commitments and time available to advise and help students procure such relationships. Study recommendations point to preparing IDS science PhD graduates for diverse career paths by emphasizing math, technical, communication, and interdisciplinary skills using experiential learning opportunities such as internships and an IDS project-based curriculum.
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Date Issued: 2017
Identifier: CFE0007285, ucf:52159
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007285

Title: A Comparative Study of Two Models of Presenting Phrasal Verbs.
Creator: Majeed, Nagham, Mihai, Florin, Folse, Keith, Purmensky, Kerry, Boote, David, University of Central Florida
Abstract / Description: Learning phrasal verbs (PVs) is of vital importance in both written and spokenEnglish, especially for those English learners who must use English as a second language (ESL) in their daily interactions with proficient speakers. This study focused on two particles (out and in) in exploring a more effective model for presenting PVs in an ESL context. PVs are the focus of this empirical study because they are an essential component of English vocabulary but are typically regarded as very...
Show moreLearning phrasal verbs (PVs) is of vital importance in both written and spokenEnglish, especially for those English learners who must use English as a second language (ESL) in their daily interactions with proficient speakers. This study focused on two particles (out and in) in exploring a more effective model for presenting PVs in an ESL context. PVs are the focus of this empirical study because they are an essential component of English vocabulary but are typically regarded as very difficult for ESL students to master.This study used a quasi-experimental design to compare the effect of instruction through image-schematic container illustrations of 16 PVs (supported by the container metaphor model) and a definition-only illustration of the same 16 PVs (supported by the traditional model of PV instruction). The participants in this experiment consisted of 28 intermediate-level students enrolled in intensive English program (IEP) courses at a metropolitan college in the southeastern United States during the summer of 2019; the students were divided into a control group and an experimental group. Four types of instruments, including one pretest and three posttests, were used in this experiment to examine the effectiveness of the container metaphor model compared with the traditional model. The findings of this study challenge the traditional view regarding the difficulty of teaching the meanings of these 16 PVs and suggest that the container metaphor model is more conducive to PV learning and retention. However, the findings of this study showed little evidence that the container metaphor model can assist in guessing the meaning of previously unknown PVs. The practical implications demonstrated from these results can be used by ESL teachers and educational stakeholders to validate English-teaching practices. Therefore, this model was recommended to be considered as one model of presenting PVs. The current study demonstrated that researchers should include infrequent PVs in their research in addition to the frequent ones. Finally, limitations of the current study are identified and recommendations for organizing future studies on this topic are proposed.
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Date Issued: 2019
Identifier: CFE0007834, ucf:52829
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007834

Title: Examining High School Teachers' Technology Acceptation of A Learning Management System in A Large Public School District.
Creator: Foster-Hennighan, Shari, Butler, Malcolm, Hewitt, Randall, Boote, David, Swan, Bonnie, University of Central Florida
Abstract / Description: The purpose of this research study was to understand high school teachers' acceptance and use of Canvas Learning Management System (LMS) (Canvas, 2011) in a large public school district. Teachers are the keystone species within the educational environment, and as such, are critical for the successful integration of technology in the classroom (Davis, Eickelmann, (&) Zaka, 2013). Therefore, in order to facilitate teacher's acceptance and use of technology for instructional purposes, those...
Show moreThe purpose of this research study was to understand high school teachers' acceptance and use of Canvas Learning Management System (LMS) (Canvas, 2011) in a large public school district. Teachers are the keystone species within the educational environment, and as such, are critical for the successful integration of technology in the classroom (Davis, Eickelmann, (&) Zaka, 2013). Therefore, in order to facilitate teacher's acceptance and use of technology for instructional purposes, those factors that influence or prevent use need to be understood. This study used a revised Technology Acceptance Model (Fathema, Shannon, (&) Ross, 2015) to determine those factors that affect teachers' actual informational and communicational use of the Canvas LMS (Canvas, 2011). This mixed methods study used a survey and interview to answer three research questions concerning acceptance, use, and departmental influence on the use of Canvas LMS. The survey data were analyzed with Exploratory Factor Analysis (EFA) and Structural Equation Modeling (SEM) in order to produce two explanatory models to address the three research questions. The semi-structured interviews were conducted with 16 teachers from one high school in a large public school district. The interview questions were transcribed, coded, and themed in order to answer research questions two and three. The analysis of the survey and interview data found that teachers were more likely to use informational rather than communicational features in Canvas. Communicational use differences were more evident than informational use among the four core subject areas, with mathematics using these features the least. For both models of survey data, the quality of the Canvas system was an influence on teacher use. The influence of teacher intent was contradictory between the two models. The findings from this study can be used to inform stakeholders of factors that influence high school teachers Canvas use, and recommendations to improve integration in the future.
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Date Issued: 2019
Identifier: CFE0007631, ucf:52478
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007631

Title: Mathematical Investigation of the Spatial Spread of an Infectious Disease in a Heterogeneous Environment.
Creator: Gaudiello, Arielle, Shuai, Zhisheng, Nevai, A, Song, Zixia, Mohapatra, Ram, Quintana-Ascencio, Pedro, University of Central Florida
Abstract / Description: Outbreaks of infectious diseases can devastate a population. Researchers thus study the spread of an infection in a habitat to learn methods of control. In mathematical epidemiology, disease transmission is often assumed to adhere to the law of mass action, yet there are numerous other incidence terms existing in the literature. With recent global outbreaks and epidemics, spatial heterogeneity has been at the forefront of these epidemiological models.We formulate and analyze a model for...
Show moreOutbreaks of infectious diseases can devastate a population. Researchers thus study the spread of an infection in a habitat to learn methods of control. In mathematical epidemiology, disease transmission is often assumed to adhere to the law of mass action, yet there are numerous other incidence terms existing in the literature. With recent global outbreaks and epidemics, spatial heterogeneity has been at the forefront of these epidemiological models.We formulate and analyze a model for humans in a homogeneous population with a nonlinear incidence function and demographics of birth and death. We allow for the combination of host immunity after recovery from infection or host susceptibility once the infection has run its course in the individual. We compute the basic reproduction number, R0, for the system and determine the global stability of the equilibrium states. If R0(<)= 1, the population tends towards a disease-free state. If R0 (>)1, an endemic equilibrium exists, and the disease is persistent in the population. This work provides the framework needed for a spatially heterogeneous model. The model is then expanded to include a set of cities (or patches), each of which is structured from the homogeneous model. Movement is introduced, allowing travel between the cities at different rates. We assume there always exists a potentially non-direct route between two cities, and the movement need not be symmetric between two patches. Further, each city has its own nonlinear incidence function, demographics, and recovery rates, allowing for realistic interpretations of country-wide network structures. New global stability results are established for the disease-free equilibrium and endemic equilibrium, the latter utilizing a graph theoretic approach and Lyapunov functions. Asymptotic profiles are determined for both the disease-free equilibrium and basic reproduction number as the diffusion of human individuals is faster than the disease dynamics. A numerical investigation is performed on a star network, emulating a rural-urban society with a center city and surrounding suburbs. Numerical simulations give rise to similar and contrasting behavior for symmetric movement to the proposed asymmetric movement. Conjectures are made for the monotonicty of the basic reproduction number in terms of the diffusion of susceptible and infectious individuals. The limiting behavior of the system as the diffusion of susceptibles halts is shown to experience varying behavior based on the location of hot spots and biased movement.
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Date Issued: 2019
Identifier: CFE0007637, ucf:52463
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007637

Title: QUANTIFYING THE IMPACTS OF THE 2007 ECONOMIC CRISIS ON A LOCAL TOURISM INDUSTRY AND REGIONAL ECONOMY.
Creator: Zhong, Yun Ying, Tadayuki, Hara, University of Central Florida
Abstract / Description: The purpose of the study is to explore the accuracy of the Input-Output model and its derivative, the Occupation-Based model in investigating the impacts of the 2007 economic crisis on the tourism-related industries and the local economy in the Metro Orlando Area, Florida. The 2007-2008 total visitor expenditure change is taken as an initial shock from the economic crisis on the region's tourism-related industries, and the total impacts are measured in terms of industry output (sales),...
Show moreThe purpose of the study is to explore the accuracy of the Input-Output model and its derivative, the Occupation-Based model in investigating the impacts of the 2007 economic crisis on the tourism-related industries and the local economy in the Metro Orlando Area, Florida. The 2007-2008 total visitor expenditure change is taken as an initial shock from the economic crisis on the region's tourism-related industries, and the total impacts are measured in terms of industry output (sales), employment and annual occupational wage. The estimation results are compared with the actual data to verify the accuracy of the modeling results. Paired-sample T tests are performed to determine whether the difference between the actual and estimated results are statistically significant or not. The findings suggest that the Input-Output model tends to overestimate the negative effects from the 2007 economic crisis in terms of output and employment, especially on the tourism-related industries. While the estimation results indicate the 2007 economic crisis greatly damaged the local tourism-related industries between 2007 and 2008, the actual data show that most of these industries experienced output and employment growth in that one year period. Moreover, the study findings also indicate that the Occupation-Based model has the tendency of overestimating the annual wage loss, especially for the occupations which take up large employment ratio in an industry. By investigating the local economic activities during the study period, this study made some explorative efforts in explaining such discrepancies. Theoretical and practical implications are then suggested
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Date Issued: 2011
Identifier: CFE0003582, ucf:48897
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003582

Title: Conservation and population biology: genetics, demography and habitat requirements of the Atlantic coast beach mice.
Creator: Kalkvik, Haakon, Parkinson, Christopher, Stout, I, Hoffman, Eric, Weishampel, John, Doonan, Terry, University of Central Florida
Abstract / Description: The conservation biology field seeks to preserve biodiversity and the processes shaping that variation. Conservation biology is intimately tied to evolutionary research, in order to identify evolutionary distinct lineages that may be in danger of disappearing. Interestingly, patterns and processes of lineage divergence and persistence change with respect to spatial and temporal scale. I seek to evaluate biodiversity, the factors that have shaped this heterogeneity, and how this variability...
Show moreThe conservation biology field seeks to preserve biodiversity and the processes shaping that variation. Conservation biology is intimately tied to evolutionary research, in order to identify evolutionary distinct lineages that may be in danger of disappearing. Interestingly, patterns and processes of lineage divergence and persistence change with respect to spatial and temporal scale. I seek to evaluate biodiversity, the factors that have shaped this heterogeneity, and how this variability persists. To accomplish this I used a phylogeographic approach as well as niche and population modeling on the Peromyscus maniculatus species group found widely distributed in North America. My emphasis was on the southeastern U.S. species P. polionotus and its distinct beach forms. At a continental scale, I found that environmental niches are likely involved in generating and/or maintaining genetic lineages within the P. maniculatus species group. These findings add to a growing number of studies that have identified lineages occupying different environmental spaces. At a regional scale, I supported the hypothesis that barrier islands on the Atlantic coast of Florida were colonized by an ancestral form of P. polionotus by a single colonization, from the central Florida area. Subsequently, at least two distinct lineages diverged (P. p. phasma and P. p. niveiventris). I also found evidence that suggests that the extinct form of beach mouse (P. p. decoloratus) is part of the P. p. phasma lineage. At the population level, I evaluated changes in genetic diversity in historical samples compared to those that experienced recent human encroachment on natural habitat I used tissue preserved in natural history collections to compare with live-trapped specimens, and found that P. p. niveiventris has maintained historical genetic diversity levels. I suggest that the continuation of historical levels of genetic diversity is due to the presence of a single large area of continuous habitat in the central portion of the species' current distribution. Finally, I evaluated the importance of scrub and beach habitat to the population dynamics of beach mice. Beach mice have traditionally have been associated with beach dunes rather than with the scrub habitat found more inland on barrier islands. Using almost three years of capture-recapture data from Cape Canaveral Air Force Station (CCAFS), I created a stochastic matrix model to assess the relative contribution of populations from the two different habitats to a variety of demographic measures. Both field data and model results provided evidence that the population dynamics of beach mice may rely much more on scrub habitat than formerly documented. Overall, my research emphasized a hierarchical approach to evaluate biodiversity and the processes shaping differentiation at different spatial and temporal scales. The methods and findings give insight into speciation at different scales, and can be applied to a wide range of taxa for questions related to evolutionary and conservation biology.
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Date Issued: 2012
Identifier: CFE0004392, ucf:49372
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004392

Title: NUMERICAL MODELING OF THE SHOCK TUBE FLOW FIELDS BEFORE ANDDURING IGNITION DELAY TIME EXPERIMENTS AT PRACTICAL CONDITIONS.
Creator: lamnaouer, mouna, Kassab, Alain, University of Central Florida
Abstract / Description: An axi-symmetric shock-tube model has been developed to simulate the shock-wave propagation and reflection in both non-reactive and reactive flows. Simulations were performed for the full shock-tube geometry of the high-pressure shock tube facility at Texas A&M University. Computations were carried out in the CFD solver FLUENT based on the finite volume approach and the AUSM+ flux differencing scheme. Adaptive mesh refinement (AMR) algorithm was applied to the time-dependent flow fields to...
Show moreAn axi-symmetric shock-tube model has been developed to simulate the shock-wave propagation and reflection in both non-reactive and reactive flows. Simulations were performed for the full shock-tube geometry of the high-pressure shock tube facility at Texas A&M University. Computations were carried out in the CFD solver FLUENT based on the finite volume approach and the AUSM+ flux differencing scheme. Adaptive mesh refinement (AMR) algorithm was applied to the time-dependent flow fields to accurately capture and resolve the shock and contact discontinuities as well as the very fine scales associated with the viscous and reactive effects. A conjugate heat transfer model has been incorporated which enhanced the credibility of the simulations. The multi-dimensional, time-dependent numerical simulations resolved all of the relevant scales, ranging from the size of the system to the reaction zone scale. The robustness of the numerical model and the accuracy of the simulations were assessed through validation with the analytical ideal shock-tube theory and experimental data. The numerical method is first applied to the problem of axi-symmetric inviscid flow then viscous effects are incorporated through viscous modeling. The non-idealities in the shock tube have been investigated and quantified, notably the non-ideal transient behavior in the shock tube nozzle section, heat transfer effects from the hot gas to the shock tube side walls, the reflected shock/boundary layer interactions or what is known as bifurcation, and the contact surface/bifurcation interaction resulting into driver gas contamination. The non-reactive model is shown to be capable of accurately simulating the shock and expansion wave propagations and reflections as well as the flow non-uniformities behind the reflected shock wave. Both the inviscid and the viscous non-reactive models provided a baseline for the combustion model iii which involves elementary chemical reactions and requires the coupling of the chemistry with the flow fields adding to the complexity of the problem and thereby requiring tremendous computational resources. Combustion modeling focuses on the ignition process behind the reflected shock wave in undiluted and diluted Hydrogen test gas mixtures. Accurate representation of the Shock Ã‚Â–tube reactive flow fields is more likely to be achieved by the means of the LES model in conjunction with the EDC model. The shock-tube CFD model developed herein provides valuable information to the interpretation of the shock-tube experimental data and to the understanding of the impact the facility-dependent non-idealities can have on the ignition delay time measurements.
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Date Issued: 2010
Identifier: CFE0003011, ucf:48366
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003011

Title: FUNDAMENTAL STUDY OF MECHANICAL AND CHEMICAL DEGRADATION MECHANISMS OF PEM FUEL CELL MEMBRANES.
Creator: Yoon, Wonseok, Huang, Xinyu, University of Central Florida
Abstract / Description: One of the important factors determining the lifetime of polymer electrolyte membrane fuel cells (PEMFCs) is membrane degradation and failure. The lack of effective mitigation methods is largely due to the currently very limited understanding of the underlying mechanisms for mechanical and chemical degradations of fuel cell membranes. In order to understand degradation of membranes in fuel cells, two different experimental approaches were developed; one is fuel cell testing under open circuit...
Show moreOne of the important factors determining the lifetime of polymer electrolyte membrane fuel cells (PEMFCs) is membrane degradation and failure. The lack of effective mitigation methods is largely due to the currently very limited understanding of the underlying mechanisms for mechanical and chemical degradations of fuel cell membranes. In order to understand degradation of membranes in fuel cells, two different experimental approaches were developed; one is fuel cell testing under open circuit voltage (OCV) with bi-layer configuration of the membrane electrode assemblies (MEAs) and the other is a modified gas phase FentonÃ‚Â's test. Accelerated degradation tests for polymer electrolyte membrane (PEM) fuel cells are frequently conducted under open circuit voltage (OCV) conditions at low relative humidity (RH) and high temperature. With the bi-layer MEA technique, it was found that membrane degradation is highly localized across thickness direction of the membrane and qualitatively correlated with location of platinum (Pt) band through mechanical testing, Infrared (IR) spectroscopy, fluoride emission, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS) measurement. One of the critical experimental observations is that mechanical behavior of membranes subjected to degradation via FentonÃ‚Â's reaction exhibit completely different behavior with that of membranes from the OCV testing. This result led us to believe that other critical factors such as mechanical stress may affect on membrane degradation and therefore, a modified gas phase FentonÃ‚Â's test setup was developed to test the hypothesis. Interestingly, the results showed that mechanical stress directly accelerates the degradation rate of ionomer membranes, implying that the rate constant for the degradation reaction is a function of mechanical stress in addition to commonly known factors such as temperature and humidity. Membrane degradation induced by mechanical stress necessitates the prediction of the stress distribution in the membrane under various conditions. One of research focuses was on the developing micromechanism-inspired continuum model for ionomer membranes. The model is the basis for stress analysis, and is based on a hyperelastic model with reptation-inspired viscous flow rule and multiplicative decomposition of viscoelastic and plastic deformation gradient. Finally, evaluation of the membrane degradation requires a fuel cell model since the degradation occurs under fuel cell operating conditions. The fuel cell model included structural mechanics models and multiphysics models which represents other phenomena such as gas and water transport, charge conservation, electrochemical reactions, and energy conservation. The combined model was developed to investigate the compression effect on fuel cell performance and membrane stress distribution.
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Date Issued: 2010
Identifier: CFE0003006, ucf:48359
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003006

Title: ANALYSIS AND OPTIMIZATION OF A SOLAR THERMAL COLLECTOR WITH INTEGRATED STORAGE.
Creator: Bonadies, Monica, Kapat, Jay, University of Central Florida
Abstract / Description: Solar energy, a topic popular in the United States during the oil embargo of the 1970Ã‚Â's, has become a relevant topic once more with the current focus on reducing greenhouse emissions. Solar thermal energy in particular has become popular as it uses existing steam turbine technology to produce electricity, with the benefit of using solar energy to produce steam rather than coal or nuclear heat sources. Solar thermal can also be used at lower temperatures to heat water...
Show moreSolar energy, a topic popular in the United States during the oil embargo of the 1970Ã‚Â's, has become a relevant topic once more with the current focus on reducing greenhouse emissions. Solar thermal energy in particular has become popular as it uses existing steam turbine technology to produce electricity, with the benefit of using solar energy to produce steam rather than coal or nuclear heat sources. Solar thermal can also be used at lower temperatures to heat water for pools or for residential use. While this energy source has its benefits, it has the problem of being opportunistic Ã‚Â– the energy must be used as it is captured. With the integration of storage, a solar thermal system becomes more viable for use. In this work, a low temperature (50-70o C) thermal storage unit with a solar thermal collector is experimentally run then studied using both analytical and numerical methods. With these methods, suggestions for future developments of the storage unit are made. The prototype collector and storage combination tested worked best during the winter months, when there was low humidity. Furthermore, the heat exchanger design within the storage unit was found to work well for charging (heating) the unit, but not for discharging the storage to heat water. The best modeling method for the storage unit was the use of FLUENT, which would allow for the suggested changes to the prototype to be simulated before the next prototype was constructed.
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Date Issued: 2010
Identifier: CFE0003260, ucf:48548
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003260

Title: Computational Fluid Dynamics Proof of Concept and Analysis of a Self-Powered Fontan Circulation.
Creator: Ni, Marcus, Kassab, Alain, Divo, Eduardo, Chopra, Manoj, University of Central Florida
Abstract / Description: The Fontan circulation is a result of the last (third stage) surgical procedure to correct a single ventricle congenital cardiac disorder in children. Although the Fontan circulation has been successfully established in surgeries over the years, it is flawed and can lead in certain cases to pre-mature death. The main cause of this failure is due to increased pulmonary vascular resistance due to loss pulse pressure and blood flow. In healthy circulations, the heart pumps directly to the lungs,...
Show moreThe Fontan circulation is a result of the last (third stage) surgical procedure to correct a single ventricle congenital cardiac disorder in children. Although the Fontan circulation has been successfully established in surgeries over the years, it is flawed and can lead in certain cases to pre-mature death. The main cause of this failure is due to increased pulmonary vascular resistance due to loss pulse pressure and blood flow. In healthy circulations, the heart pumps directly to the lungs, where as (")Single Ventricle(") patients must use a single sided heart to supply blood to the rest of the body before the lungs. Improvements to the Fontan circulation have been proposed, but they require extensive care or external devices. We propose a (")Self-Powered(") Fontan circulation that will inject energy into the pulmonary system by adding an injection jet shunt (IJS) directly from the heart. The IJS will provide the pulse pressure, blood flow, and entrainment that the pulmonary vascular system needs to function at a healthy level. The difference between a healthy and sick Fontan circulation is 3-5[mmHg] in the IVC. The goal of the IJS is to cause this 3-5[mmHg] pressure drop in the IVC. In the analysis of the Fontan, ascertaining energy losses due to flow jet impingements and flow mixing is critical. Moreover, in order to better understand surgical alternatives is it important to have a robust multi-scale 0D-3D CFD analysis tool that permits investigation of surgical alternatives in a virtual physics-based environment. To this end, a lumped parameter model (LPM) is tightly coupled at the time step level with a full 3D computational fluid dynamics (CFD) model. Using this model scheme, the Fontan test section is no longer being modeled by the LPM. Therefore, it is not limited by the 0D nature of the vascular resistance, capacitance, and inertia bed model. The CFD can take over at the area of interest which accounts for flow directionality and momentum transfer that the LPM is unable to capture. To efficiently calculate optimal IJS configurations, a closed loop steady state model was created to solve a simplified Fontan circulation in 3D. Three models were created with several different optimized configurations, a synthetic model (average dimensions of 2-4 year-old Fontan patients), and two patient-specific models (10 and 24-year-old). The model configurations include changes in the IJS nozzle diameter and IJS placement along the pulmonary artery. These configurations are compared to a baseline model with no IJS. All three models suggest that the IJS helps to decrease IVC pressure while increasing pulse pressure and blood flow to the pulmonary system.
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Date Issued: 2017
Identifier: CFE0006630, ucf:51303
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006630

Title: Model Selection via Racing.
Creator: Zhang, Tiantian, Georgiopoulos, Michael, Anagnostopoulos, Georgios, Wu, Annie, Hu, Haiyan, Nickerson, David, University of Central Florida
Abstract / Description: Model Selection (MS) is an important aspect of machine learning, as necessitated by the No Free Lunch theorem. Briefly speaking, the task of MS is to identify a subset of models that are optimal in terms of pre-selected optimization criteria. There are many practical applications of MS, such as model parameter tuning, personalized recommendations, A/B testing, etc. Lately, some MS research has focused on trading off exactness of the optimization with somewhat alleviating the computational...
Show moreModel Selection (MS) is an important aspect of machine learning, as necessitated by the No Free Lunch theorem. Briefly speaking, the task of MS is to identify a subset of models that are optimal in terms of pre-selected optimization criteria. There are many practical applications of MS, such as model parameter tuning, personalized recommendations, A/B testing, etc. Lately, some MS research has focused on trading off exactness of the optimization with somewhat alleviating the computational burden entailed. Recent attempts along this line include metaheuristics optimization, local search-based approaches, sequential model-based methods, portfolio algorithm approaches, and multi-armed bandits.Racing Algorithms (RAs) are an active research area in MS, which trade off some computational cost for a reduced, but acceptable likelihood that the models returned are indeed optimal among the given ensemble of models. All existing RAs in the literature are designed as Single-Objective Racing Algorithm (SORA) for Single-Objective Model Selection (SOMS), where a single optimization criterion is considered for measuring the goodness of models. Moreover, they are offline algorithms in which MS occurs before model deployment and the selected models are optimal in terms of their overall average performances on a validation set of problem instances. This work aims to investigate racing approaches along two distinct directions: Extreme Model Selection (EMS) and Multi-Objective Model Selection (MOMS). In EMS, given a problem instance and a limited computational budget shared among all the candidate models, one is interested in maximizing the final solution quality. In such a setting, MS occurs during model comparison in terms of maximum performance and involves no model validation. EMS is a natural framework for many applications. However, EMS problems remain unaddressed by current racing approaches. In this work, the first RA for EMS, named Max-Race, is developed, so that it optimizes the extreme solution quality by automatically allocating the computational resources among an ensemble of problem solvers for a given problem instance. In Max-Race, significant difference between the extreme performances of any pair of models is statistically inferred via a parametric hypothesis test under the Generalized Pareto Distribution (GPD) assumption. Experimental results have confirmed that Max-Race is capable of identifying the best extreme model with high accuracy and low computational cost. Furthermore, in machine learning, as well as in many real-world applications, a variety of MS problems are multi-objective in nature. MS which simultaneously considers multiple optimization criteria is referred to as MOMS. Under this scheme, a set of Pareto optimal models is sought that reflect a variety of compromises between optimization objectives. So far, MOMS problems have received little attention in the relevant literature. Therefore, this work also develops the first Multi-Objective Racing Algorithm (MORA) for a fixed-budget setting, namely S-Race. S-Race addresses MOMS in the proper sense of Pareto optimality. Its key decision mechanism is the non-parametric sign test, which is employed for inferring pairwise dominance relationships. Moreover, S-Race is able to strictly control the overall probability of falsely eliminating any non-dominated models at a user-specified significance level. Additionally, SPRINT-Race, the first MORA for a fixed-confidence setting, is also developed. In SPRINT-Race, pairwise dominance and non-dominance relationships are established via the Sequential Probability Ratio Test with an Indifference zone. Moreover, the overall probability of falsely eliminating any non-dominated models or mistakenly retaining any dominated models is controlled at a prescribed significance level. Extensive experimental analysis has demonstrated the efficiency and advantages of both S-Race and SPRINT-Race in MOMS.
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Date Issued: 2016
Identifier: CFE0006203, ucf:51094
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006203

Title: Modeling User Transportation Patterns Using Mobile Devices.
Creator: Davami, Erfan, Sukthankar, Gita, Gonzalez, Avelino, Foroosh, Hassan, Sukthankar, Rahul, University of Central Florida
Abstract / Description: Participatory sensing frameworks use humans and their computing devices as a large mobile sensing network. Dramatic accessibility and affordability have turned mobile devices (smartphone and tablet computers) into the most popular computational machines in the world, exceeding laptops. By the end of 2013, more than 1.5 billion people on earth will have a smartphone. Increased coverage and higher speeds of cellular networks have given these devices the power to constantly stream large amounts...
Show moreParticipatory sensing frameworks use humans and their computing devices as a large mobile sensing network. Dramatic accessibility and affordability have turned mobile devices (smartphone and tablet computers) into the most popular computational machines in the world, exceeding laptops. By the end of 2013, more than 1.5 billion people on earth will have a smartphone. Increased coverage and higher speeds of cellular networks have given these devices the power to constantly stream large amounts of data.Most mobile devices are equipped with advanced sensors such as GPS, cameras, and microphones. This expansion of smartphone numbers and power has created a sensing system capable of achieving tasks practically impossible for conventional sensing platforms. One of the advantages of participatory sensing platforms is their mobility, since human users are often in motion. This dissertation presents a set of techniques for modeling and predicting user transportation patterns from cell-phone and social media check-ins. To study large-scale transportation patterns, I created a mobile phone app, Kpark, for estimating parking lot occupancy on the UCF campus. Kpark aggregates individual user reports on parking space availability to produce a global picture across all the campus lots using crowdsourcing. An issue with crowdsourcing is the possibility of receiving inaccurate information from users, either through error or malicious motivations. One method of combating this problem is to model the trustworthiness of individual participants to use that information to selectively include or discard data.This dissertation presents a comprehensive study of the performance of different worker quality and data fusion models with plausible simulated user populations, as well as an evaluation of their performance on the real data obtained from a full release of the Kpark app on the UCF Orlando campus. To evaluate individual trust prediction methods, an algorithm selection portfolio was introduced to take advantage of the strengths of each method and maximize the overall prediction performance.Like many other crowdsourced applications, user incentivization is an important aspect of creating a successful crowdsourcing workflow. For this project a form of non-monetized incentivization called gamification was used in order to create competition among users with the aim of increasing the quantity and quality of data submitted to the project. This dissertation reports on the performance of Kpark at predicting parking occupancy, increasing user app usage, and predicting worker quality.
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Date Issued: 2015
Identifier: CFE0005597, ucf:50258
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005597

Title: Influence of Task-Role Mental Models on Human Interpretation of Robot Motion Behavior.
Creator: Ososky, Scott, Jentsch, Florian, Shumaker, Randall, Fiore, Stephen, Lackey, Stephanie, University of Central Florida
Abstract / Description: The transition in robotics from tools to teammates has begun. However, the benefit autonomous robots provide will be diminished if human teammates misinterpret robot behaviors. Applying mental model theory as the organizing framework for human understanding of robots, the current empirical study examined the influence of task-role mental models of robots on the interpretation of robot motion behaviors, and the resulting impact on subjective ratings of robots. Observers (N = 120) were exposed...
Show moreThe transition in robotics from tools to teammates has begun. However, the benefit autonomous robots provide will be diminished if human teammates misinterpret robot behaviors. Applying mental model theory as the organizing framework for human understanding of robots, the current empirical study examined the influence of task-role mental models of robots on the interpretation of robot motion behaviors, and the resulting impact on subjective ratings of robots. Observers (N = 120) were exposed to robot behaviors that were either congruent or incongruent with their task-role mental model, by experimental manipulation of preparatory robot task-role information to influence mental models (i.e., security guard, groundskeeper, or no information), the robot's actual task-role behaviors (i.e., security guard or groundskeeper), and the order in which these robot behaviors were presented. The results of the research supported the hypothesis that observers with congruent mental models were significantly more accurate in interpreting the motion behaviors of the robot than observers without a specific mental model. Additionally, an incongruent mental model, under certain circumstances, significantly hindered an observer's interpretation accuracy, resulting in subjective sureness of inaccurate interpretations. The strength of the effects that mental models had on the interpretation and assessment of robot behaviors was thought to have been moderated by the ease with which a particular mental model could reasonably explain the robot's behavior, termed mental model applicability. Finally, positive associations were found between differences in observers' interpretation accuracy and differences in subjective ratings of robot intelligence, safety, and trustworthiness. The current research offers implications for the relationships between mental model components, as well as implications for designing robot behaviors to appear more transparent, or opaque, to humans.
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Date Issued: 2013
Identifier: CFE0005391, ucf:50457
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005391

Title: Multi-Physics Model of Key Components In High Efficiency Vehicle Drive.
Creator: Lin, Shao Hua, Wu, Xinzhang, Sundaram, Kalpathy, Wahid, Parveen, Wei, Lei, Chow, Louis, University of Central Florida
Abstract / Description: Hybrid Electric Vehicles (HEVs) and Electric Vehicles (EVs) are crucial technologies for the automotive industry to meet society's demands for cleaner, more energy efficient transportation. Meeting the need to provide power which sustains HEVs and EVs is an immediate area of concern that research and development within the automotive community must address. Electric batteries and electrical motors are the key components in HEV and EV power generation and transmission, and their performance...
Show moreHybrid Electric Vehicles (HEVs) and Electric Vehicles (EVs) are crucial technologies for the automotive industry to meet society's demands for cleaner, more energy efficient transportation. Meeting the need to provide power which sustains HEVs and EVs is an immediate area of concern that research and development within the automotive community must address. Electric batteries and electrical motors are the key components in HEV and EV power generation and transmission, and their performance plays very important role in the overall performance of the modern high efficiency vehicles. Therefore, in this dissertation, we are motivated to study the electric batteries, interior permanent motor (IPM), in the context of modern hybrid electric/electric drive systems, from both multi-physics and system level perspectives. Electrical circuit theory, electromagnetic Finite Element Analysis (FEA), and Computational Fluid Dynamic (CFD) finite volume method will be used primarily in this work. The work has total of five parts, and they are introduced in the following.Firstly, Battery thermal management design is critical in HEV and EV development. Accurate temperature distribution of the battery cells during vehicle operation is required for achieving optimized design. We propose a novel electrical-thermal battery modeling technique that couples a temperature dependent battery circuit model and a physics-based CFD model to meet this need. The electrical circuit model serves as a heat generation mechanism for the CFD model, and the CFD model provides the temperature distribution of the battery cells, which can also impact the heat generation of the electrical battery model. In this part of work, simulation data has been derived from the model respective to electrical performance of the battery as well as the temperature distribution simultaneously in consideration of the physical dimensions, material properties, and cooling conditions. The proposed model is validated against a battery model that couples the same electrical model with a known equivalent thermal model.Secondly, we propose an accurate system level Foster network thermal model. The parameters of the model are extracted from step responses of the CFD battery thermal model. The Foster network model and the CFD model give the same results. The Foster network can couple with battery circuit model to form an electric-thermal battery model for system simulation.Thirdly, IPM electric machines are important in high performance drive systems. During normal operations, irreversible demagnetization can occur due to temperature rise and various loading conditions. We investigate the performance of an IPM using 3d time stepping electromagnetic FEA considering magnet's temperature dependency. Torque, flux linkage, induced voltage, inductance and saliency of the IPM will be studied in details. Finally, we use CFD to predict the non-uniform temperature distribution of the IPM machine and the impact of this distribution on motor performance. Fourthly, we will switch gear to investigate the IPM motor on the system level. A reduced order IPM model is proposed to consider the effect of demagnetization of permanent magnet due to temperature effect. The proposed model is validated by comparing its results to the FEA results.Finally, a HEV is a vehicle that has both conventional mechanical (i.e. internal combustion engine) and electrical propulsion systems. The electrical powertrain is used to work with the conventional powertrain to achieve higher fuel economy and lower emissions. Computer based modeling and simulation techniques are therefore essential to help reduce the design cost and optimize system performance. Due to the complexity of hybrid vehicles, multi-domain modeling ability is preferred for both component modeling and system simulation. We present a HEV library developed using VHDL-AMS.
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Date Issued: 2013
Identifier: CFE0005024, ucf:50016
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005024

Title: Quantifying Ultra-high Performance Concrete Flexural System Mechanical Response.
Creator: Xiao, Yulin, Mackie, Kevin, Catbas, Necati, Chopra, Manoj, Gordon, Ali, University of Central Florida
Abstract / Description: The research and application of Ultra-high Performance Concrete (UHPC) has been developedsignificantly within the last 1-2 decades. Due to the specific property of high strength capacity, it is potential to be used in bridge deck system without shear reinforcement so that it provides even lighter self-weight of the deck. However, one of the shear component, dowel action, has not beenadequately investigated in the past. In this dissertation, a particular test was designed and carried out to...
Show moreThe research and application of Ultra-high Performance Concrete (UHPC) has been developedsignificantly within the last 1-2 decades. Due to the specific property of high strength capacity, it is potential to be used in bridge deck system without shear reinforcement so that it provides even lighter self-weight of the deck. However, one of the shear component, dowel action, has not beenadequately investigated in the past. In this dissertation, a particular test was designed and carried out to fully investigate the dowel action response, especially its contribution to shear resistance. In addition, research on serviceability and fatigue behaviors were expanded as well to delete the concern on other factors that may influence the application to the deck system. Both experimental and analytical methods including finite element modeling, OpenSees modeling and other extension studies were presented throughout the entire dissertation where required.
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Date Issued: 2014
Identifier: CFE0005563, ucf:50288
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005563

Title: INTEGRAL PROJECTION MODELS REVEAL INTERACTIVE EFFECTS OF BIOTIC FACTORS AND DISTURBANCE ON PLANT DEMOGRAPHY.
Creator: Tye, Matthew, Quintana-Ascencio, Pedro, Fauth, John, Nevai, Andrew, Menges, Eric, University of Central Florida
Abstract / Description: Understanding factors limiting population growth is crucial to evaluating species persistence in changing environments. I used Integral Projection Models (IPMs) to elucidate the role of biotic interactions and disturbance on population growth rate in two plants: Helianthemum squamatum, a perennial endemic to gypsum habitats in central Spain, and Liatris ohlingerae, a long-lived perennial endemic to the Lake Wales Ridge of central Florida. In H. squamatum, there was a strong positive effect of...
Show moreUnderstanding factors limiting population growth is crucial to evaluating species persistence in changing environments. I used Integral Projection Models (IPMs) to elucidate the role of biotic interactions and disturbance on population growth rate in two plants: Helianthemum squamatum, a perennial endemic to gypsum habitats in central Spain, and Liatris ohlingerae, a long-lived perennial endemic to the Lake Wales Ridge of central Florida. In H. squamatum, there was a strong positive effect of trampling in the site with the highest plant density and moderate positive effects of seed addition in the site with the lowest plant density. Differences in treatment effectiveness between sites may represent a shift from seed to microsite limitation at increasing densities. Additionally, a distinct drop in population growth rate occurred in the hottest and driest year (2009-10). In Liatris ohlingerae, roadside populations had consistently higher population growth rates than scrub populations. A modest negative effect of time-since-fire was observed in plants that did not experience herbivory. Both habitat and time-since-fire showed distinct interactions with vertebrate herbivory, with herbivory increasing the difference in growth rate between habitats and decreasing the difference between time-since-fire classes. The direct effect of herbivory was negative in all environmental combinations except in long unburned populations. These results demonstrate the importance of considering environmental interactions when constructing population models, as well as the validity of using IPMs to assess interactions in species with differing life histories.
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Date Issued: 2014
Identifier: CFE0005271, ucf:50558
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005271

Title: EVALUATING THE IMPACT OF OOCEA'S DYMANIC MESSAGE SIGNS (DMS) ON TRAVELERS' EXPERIENCE USING A PRE AND POST-DEPLOYMENT SURVEY.
Creator: Flick, Jason, Al-Deek, Haitham, University of Central Florida
Abstract / Description: The purpose of this thesis was to evaluate the impact of dynamic message signs (DMS) on the Orlando-Orange County Expressway Authority (OOCEA) toll road network using a Pre and Post-Deployment DMS Survey (henceforth referred to as "pre and post-deployment survey") analysis. DMS are electronic traffic signs used on roadways to give travelers information about travel times, traffic congestion, accidents, disabled vehicles, AMBER alerts, and special events. The particular DMS referred to in this...
Show moreThe purpose of this thesis was to evaluate the impact of dynamic message signs (DMS) on the Orlando-Orange County Expressway Authority (OOCEA) toll road network using a Pre and Post-Deployment DMS Survey (henceforth referred to as "pre and post-deployment survey") analysis. DMS are electronic traffic signs used on roadways to give travelers information about travel times, traffic congestion, accidents, disabled vehicles, AMBER alerts, and special events. The particular DMS referred to in this study are large rectangular signs installed over the travel lanes and these are not the portable trailer mount signs. The OOCEA have been working over the past two years to add several fixed DMS on their toll road network. At the time of the pre-deployment survey, only one DMS was installed on the OOCEA toll road network. At the time of the post-deployment survey, a total of 30 DMS were up and running on the OOCEA toll road network. Since most of the travelers on the OOCEA toll roads are from Orange, Osceola, and Seminole counties, this study was limited to these counties. This thesis documents the results and comparisons between the pre and post-deployment survey analysis. The instrument used to analyze the travelers' perception of DMS was a survey that utilized computer aided telephone interviews. The pre-deployment survey was conducted during early November of 2006, and the post-deployment survey was conducted during the month of May, 2008. Questions pertaining to the acknowledgement of DMS on the OOCEA toll roads, satisfaction with travel information provided on the network, formatting of the messages, satisfaction with different types of messages, diversion questions (Revealed and Stated preferences), and classification/socioeconomic questions (such as age, education, most traveled toll road, county of residence, and length of residency) were asked to the respondents. The results of both the pre and post-deployment surveys are discussed in this thesis, but it should be noted that the more telling results are those of the post-deployment survey. The results of the post-deployment survey show the complete picture of the impact of DMS on travelers' experience on the OOCEA toll road network. The pre-deployment results are included to show an increase or decrease in certain aspects of travel experience with relation to DMS. The results of the pre-deployment analysis showed that 54.4% of the OOCEA travelers recalled seeing DMS on the network, while a total of 63.93% of the OOCEA travelers recalled seeing DMS during the post-deployment analysis. This showed an increase of almost 10% between the two surveys demonstrating the people are becoming more aware of DMS on the OOCEA toll road network. The respondents commonly agreed that the DMS were helpful for providing information about hazardous conditions, and that the DMS are easy to read. Also, upon further research it was found that between the pre and post-deployment surveys the travelers' satisfaction with special event information provided on DMS and travel time accuracy on DMS increased significantly. With respect to formatting of the DMS, the following methods were preferred by the majority of respondents in both the pre and post-deployment surveys: • Steady Message as a default DMS message format • Flashing Message for abnormal traffic information (94% of respondents would like to be notified of abnormal traffic information) • State road number to show which roadway (for Colonial – SR 50, Semoran – SR 436 and Alafaya – SR 434) • "I-Drive" is a good abbreviation for International Drive • If the distance to the international airport is shown on a DMS it thought to be the distance to the airport exit The results from the binary logit model for "satisfaction with travel information provided on OOCEA toll road network" displayed the significant variables that explained the likelihood of the traveler being satisfied. This satisfaction model was based on respondents who showed a prior knowledge of DMS on OOCEA toll roads. With the use of a pooled model (satisfaction model with a total of 1775 responses – 816 from pre-deployment and 959 from post-deployment), it was shown that there was no statistical change between the pre and post-deployment satisfaction based on variables thought to be theoretically relevant. The results from the comparison between the pre and post-deployment satisfaction models showed that many of the coefficients of the variables showed a significant change. Although some of the variables were statistically insignificant in one of the two survey model results: Either the pre or post-deployment model, it was still shown that every variable was significant in at least one of the two models. The coefficient for the variable corresponding to DMS accuracy showed a significantly lower value in the post-deployment model. The coefficient for the variable "DMS was helpful for providing special event information" showed a significantly higher value in the post-deployment model. The final post-deployment diversion model was based on a total of 732 responses who answered that they had experienced congestion in the past 6 months. Based on this final post-deployment diversion model, travelers who had stated that their most frequently traveled toll road was either SR 408 or SR 417 were more likely to divert. Also, travelers who stated that they would divert in the case of abnormal travel times displayed on DMS or stated that a DMS influenced their response to congestion showed a higher likelihood of diversion. These two variables were added between the pre and post-deployment surveys. It is also beneficial to note that travelers who stated they would divert in a fictitious congestion situation of at least 30 minutes of delay were more likely to divert. This shows that they do not contradict themselves in their responses to Revealed Preference and Stated Preference diversion situations. Based on a comparison between pre and post-deployment models containing similar variables, commuters were more likely to stay on the toll road everything else being equal to the base case. Also, it was shown that in the post-deployment model the respondents traveling on SR 408 and SR 417 were more likely to divert, but in the pre-deployment model only the respondents traveling on SR 408 were more likely to divert. This is an expected result since during the pre-deployment survey only one DMS was located on SR 408, and during the post-deployment survey there were DMS located on all toll roads. Also, an interesting result to be noted is that in the post-deployment survey, commuters who paid tolls with E-pass were more likely to stay on the toll road than commuters who paid tolls with cash. The implications for implementation of these results are discussed in this thesis. DMS should be formatted as a flashing message for abnormal traffic situations and the state road number should be used to identify a roadway. DMS messages should pertain to information on roadway hazards when necessary because it was found that travelers find it important to be informed on events that are related to their personal safety. The travel time accuracy on DMS was shown to be significant for traveler information satisfaction because if the travelers observe inaccurate travel times on DMS, they may not trust the validity of future messages. Finally, it is important to meet the travelers' preferences and concerns for DMS.
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Date Issued: 2008
Identifier: CFE0002295, ucf:47862
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002295

Title: Explore Contributing Geometric Factors and Built-Environment on Bicycle Activity and Safety at Intersections.
Creator: Castro, Scott, Abdel-Aty, Mohamed, Cai, Qing, Eluru, Naveen, University of Central Florida
Abstract / Description: This study attempts to explore all factors associated with bicycle motor-vehicle crashes at intersections in order to improve bicycle safety and bicycle activity. Factors such as exposure (bicycle and vehicle volumes), existing facilities (bike lanes, sidewalks, shared-use paths), geometric design (# of lanes, speed limit, medians, legs, roadway conditions), and land-use were collected and evaluated using Poisson, Zero-Inflated Poisson, and Negative Binomial models in SAS 9.4 software....
Show moreThis study attempts to explore all factors associated with bicycle motor-vehicle crashes at intersections in order to improve bicycle safety and bicycle activity. Factors such as exposure (bicycle and vehicle volumes), existing facilities (bike lanes, sidewalks, shared-use paths), geometric design (# of lanes, speed limit, medians, legs, roadway conditions), and land-use were collected and evaluated using Poisson, Zero-Inflated Poisson, and Negative Binomial models in SAS 9.4 software. Increasing the bicycle travel mode can have positive lasting effects on personal health, the environment, and improve traffic conditions. Deterrents that keep users from riding bicycles more are the lack of facilities and most importantly, safety concerns. Florida has consistently been a national leader in bicyclist deaths, which made this area a great candidate to study. Vehicle and bicycle volumes for 159 intersections in Orlando, Florida were collected and compared with crash data that was obtained. All existing facilities, geometric design properties, and land-uses for each intersection were collected for analysis. The results confirmed that an increase of motor-vehicles and bicyclists would increase the risk of a crash at an intersection. The presence of a keyhole lane (bike lane in-between a through and exclusive right turn lane), was shown to be statistically significant, and although it still had a positive correlation with injury risk, it had a much lower risk of crashes than a typical bike lane at intersections. The presence of a far shared path (more than 4 feet from the edge of curb) was shown to be statistically significant in decreasing the risk of crashes between bicycles and motor-vehicles at intersections. Institutional, agricultural, residential, government, and school land uses had positive correlations and were statistically significant with increasing activity of bicyclists at intersections. This study is unique because it uses actual bicycle volume as an exposure to determine the effects of bicycle safety and activity at intersections and not many others have done this. It is important for transportation planners and designers to use this information to design better complete streets in the future.
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Date Issued: 2018
Identifier: CFE0007318, ucf:52134
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007318

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