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Title: A mathematical model for feral cat ecology with application to disease.
Creator: Sharpe, Jeff, Nevai, A, Shuai, Zhisheng, Qi, Yuanwei, Quintana-Ascencio, Pedro, University of Central Florida
Abstract / Description: We formulate and analyze a mathematical model for feral cats living in an isolated colony. The model contains compartments for kittens, adult females and adult males. Kittens are born at a rate proportional to the population of adult females and mature at equal rates into adult females and adult males. Adults compete with each other in a manner analogous to Lotka-Volterra competition. This competition comes in four forms, classified by gender. Native house cats, and their effects are also...
Show moreWe formulate and analyze a mathematical model for feral cats living in an isolated colony. The model contains compartments for kittens, adult females and adult males. Kittens are born at a rate proportional to the population of adult females and mature at equal rates into adult females and adult males. Adults compete with each other in a manner analogous to Lotka-Volterra competition. This competition comes in four forms, classified by gender. Native house cats, and their effects are also considered, including additional competition and abandonment into the feral population. Control measures are also modeled in the form of per-capita removal rates. We compute the net reproduction number (R_0) for the colony and consider its influence. In the absence of abandonment, if R_0(>)1, the population always persists at a positive equilibrium and if R_0 (<)= 1, the population always tends toward local extinction. This work will be referred to as the core model.The model is then expanded to include a set of colonies (patches) such as those in the core model (this time neglecting the effect of abandonment). Adult females and kittens remain in their native patch while adult males spend a fixed proportion of their time in each patch. Adult females experience competition from both the adult females living in the same patch as well as the visiting adult males. The proportion of adult males in patch j suffer competition from both adult females resident to that patch as well the proportion of adult males also in the patch. We formulate a net reproduction number for each patch (a patch reproduction number) R_j. If R_j(>)1 for at least one patch, then the collective population always persists at some nontrivial (but possibly semitrivial) steady state. We consider the number of possible steady states and their properties. This work will be referred to as the patch model.Finally, the core model is expanded to include the introduction of the feline leukemia virus. Since this disease has many modes of transmission, each of which depends on the host's gender and life-stage, we regard this as a model disease. A basic reproduction number R_0 for the disease is defined and analyzed. Vaccination terms are included and their role in disease propagation is analyzed. Necessary and sufficient conditions are given under which the disease-free equilibrium is stable.
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Date Issued: 2016
Identifier: CFE0006502, ucf:51389
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006502

Title: MODELING AUTONOMOUS AGENTS IN MILITARY SIMULATIONS.
Creator: Kaptan, Varol, Gelenbe, Erol, University of Central Florida
Abstract / Description: Simulation is an important tool for prediction and assessment of the behavior of complex systems and situations. The importance of simulation has increased tremendously during the last few decades, mainly because the rapid pace of development in the field of electronics has turned the computer from a costly and obscure piece of equipment to a cheap ubiquitous tool which is now an integral part of our daily lives. While such technological improvements make it easier to analyze well-understood...
Show moreSimulation is an important tool for prediction and assessment of the behavior of complex systems and situations. The importance of simulation has increased tremendously during the last few decades, mainly because the rapid pace of development in the field of electronics has turned the computer from a costly and obscure piece of equipment to a cheap ubiquitous tool which is now an integral part of our daily lives. While such technological improvements make it easier to analyze well-understood deterministic systems, increase in speed and storage capacity alone are not enough when simulating situations where human beings and their behavior are an integral part of the system being studied. The problem with simulation of intelligent entities is that intelligence is still not well understood and it seems that the field of Artificial Intelligence (AI) has a long way to go before we get computers to think like humans. Behavior-based agent modeling has been proposed in mid-80's as one of the alternatives to the classical AI approach. While used mainly for the control of specialized robotic vehicles with very specific sensory capabilities and limited intelligence, we believe that a behavior-based approach to modeling generic autonomous agents in complex environments can provide promising results. To this end, we are investigating a behavior-based model for controlling groups of collaborating and competing agents in a geographic terrain. In this thesis, we are focusing on scenarios of military nature, where agents can move within the environment and adversaries can eliminate each other through use of weapons. Different aspects of agent behavior like navigation to a goal or staying in group formation, are implemented by distinct behavior modules and the final observed behavior for each agent is an emergent property of the combination of simple behaviors and their interaction with the environment. Our experiments show that while such an approach is quite efficient in terms of computational power, it has some major drawbacks. One of the problems is that reactive behavior-based navigation algorithms are not well suited for environments with complex mobility constraints where they tend to perform much worse than proper path planning. This problem represents an important research question, especially when it is considered that most of the modern military conflicts and operations occur in urban environments. One of the contributions of this thesis is a novel approach to reactive navigation where goals and terrain information are fused based on the idea of transforming a terrain with obstacles into a virtual obstacle-free terrain. Experimental results show that our approach can successfully combine the low run-time computational complexity of reactive methods with the high success rates of classical path planning. Another interesting research problem is how to deal with the unpredictable nature of emergent behavior. It is not uncommon to have situations where an outcome diverges significantly from the intended behavior of the agents due to highly complex nonlinear interactions with other agents or the environment itself. Chances of devising a formal way to predict and avoid such abnormalities are slim at best, mostly because such complex systems tend to be be chaotic in nature. Instead, we focus on detection of deviations through tracking group behavior which is a key component of the total situation awareness capability required by modern technology-oriented and network-centric warfare. We have designed a simple and efficient clustering algorithm for tracking of groups of agent suitable for both spatial and behavioral domain. We also show how to detect certain events of interest based on a temporal analysis of the evolution of discovered clusters.
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Date Issued: 2006
Identifier: CFE0001494, ucf:47099
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001494

Title: DEVELOPMENT OF A GRAPHICAL USER INTERFACE FOR CAL3QHC CALLED CALQCAD.
Creator: Gawalpanchi, Sheetal, Cooper, Charles, University of Central Florida
Abstract / Description: One of the major sources of air pollution in the United States metropolitan areas is due to automobiles. With the huge growth of motor vehicles and, greater dependence on them, air pollution problems have been aggravated. According to the EPA, nearly 95% of carbon monoxide (CO ) (EPA 1999) in urban areas comes from mobile sources, of which 51% is contributed by on road vehicles. It is well known fact that, carbon monoxide is one of the major mobile source pollutants and CO has detrimental...
Show moreOne of the major sources of air pollution in the United States metropolitan areas is due to automobiles. With the huge growth of motor vehicles and, greater dependence on them, air pollution problems have been aggravated. According to the EPA, nearly 95% of carbon monoxide (CO ) (EPA 1999) in urban areas comes from mobile sources, of which 51% is contributed by on road vehicles. It is well known fact that, carbon monoxide is one of the major mobile source pollutants and CO has detrimental effects on the human health. Carbon monoxide is the result of mainly incomplete combustion of gasoline in motor vehicles (FDOT 1996). The National Environmental Policy Act (NEPA) gives important considerations to the actions to be taken. Transportation conformity . The Clean Air Act Amendments (CAAA, 1970) was an important step in meeting the National Ambient Air Quality Standards In order to evaluate the effects of CO and Particulate Matter (PM) impacts based on the criteria for NAAQS standards, it is necessary to conduct dispersion modeling of emissions for mobile source emissions. Design of transportation engineering systems (roadway design) should take care of both the flow of the traffic as well as the air pollution aspects involved. Roadway projects need to conform to the State Implementation Plan (SIP) and meet the NAAQS. EPA guidelines for air quality modeling on such roadway intersections recommend the use of CAL3QHC. The model has embedded in it CALINE 3.0 (Benson 1979) – a line source dispersion model based on the Gaussian equation. The model requires parameters with respect to the roadway geometry, fleet volume, averaging time, surface roughness, emission factors, etc. The CAL3QHC model is a DOS based model which requires the modeling parameters to be fed into an input file. The creation of input the file is a tedious job. Previous work at UCF, resulted in the development of CALQVIEW, which expedites this process of creating input files, but the task of extracting the coordinates still has to be done manually. The main aim of the thesis is to reduce the analysis time for modeling emissions from roadway intersections, by expediting the process of extracting the coordinates required for the CAL3QHC model. Normally, transportation engineers design and model intersections for the traffic flow utilizing tools such as AutoCAD, Microstation etc. This thesis was to develop advanced software allowing graphical editing and coordinates capturing from an AutoCAD file. This software was named as CALQCAD. This advanced version will enable the air quality analyst to capture the coordinates from an AutoCAD 2004 file. This should expedite the process of modeling intersections and decrease analyst time from a few days to few hours. The model helps to assure the air quality analyst to retain accuracy during the modeling process. The idea to create the standalone interface was to give the AutoCAD user full functionality of AutoCAD tools in case editing is required to the main drawing. It also provides the modeler with a separate graphical user interface (GUI).
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Date Issued: 2005
Identifier: CFE0000483, ucf:46364
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000483

Title: STUDY OF SYMBOLIC EXPRESSIONS IN PEKING OPERA'SCOSTUMES AND LYRICS.
Creator: Li, Yiman, Akita, Kimiko, University of Central Florida
Abstract / Description: This thesis represents an analysis of symbolic expressions used to convey traditional Chinese cultural values in marital relations as expressed through costumes and lyrics in Peking Opera plays and performances. Two symbols, dragon and phoenix, were selected from the costume collection. Four symbols--bird, tiger, wild goose, and dragon--were selected from compilations of lyrics. These symbols were selected because they expressed Chinese core cultural values, an imperial ideology based on...
Show moreThis thesis represents an analysis of symbolic expressions used to convey traditional Chinese cultural values in marital relations as expressed through costumes and lyrics in Peking Opera plays and performances. Two symbols, dragon and phoenix, were selected from the costume collection. Four symbols--bird, tiger, wild goose, and dragon--were selected from compilations of lyrics. These symbols were selected because they expressed Chinese core cultural values, an imperial ideology based on Confucian thoughts, which were practiced rigidly during Qing Dynasty (1644-1911). Modeling Theory is applied to argue that dragon and phoenix as visual symbols convey ideas about characters' background, marital relationship, social status shifts, and socio-culturally desirable values. Social Drama Theory is employed to analyze the lyrics to understand how ideal images of husband and wife are constructed. The archetypes of Chinese traditional culture that have influenced Chinese thought and action for centuries are discovered and discussed.
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Date Issued: 2008
Identifier: CFE0002149, ucf:47505
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002149

Title: LANDCOVER CHANGE AND POPULATION DYNAMICS OF FLORIDA SCRUB-JAYS AND FLORIDA GRASSHOPPER SPARROWS.
Creator: Breininger, David, Noss, Reed, University of Central Florida
Abstract / Description: I confronted empirical habitat data (1994-2004) and population data (1988-2005) with ecological theory on habitat dynamics, recruitment, survival, and dispersal to develop predictive relationships between landcover variation and population dynamics. I focus on Florida Scrub-Jays, although one chapter presents a model for the potential influence of habitat restoration on viability of the Florida Grasshopper Sparrow. Both species are unique to Florida landscapes that are dominated by shrubs and...
Show moreI confronted empirical habitat data (1994-2004) and population data (1988-2005) with ecological theory on habitat dynamics, recruitment, survival, and dispersal to develop predictive relationships between landcover variation and population dynamics. I focus on Florida Scrub-Jays, although one chapter presents a model for the potential influence of habitat restoration on viability of the Florida Grasshopper Sparrow. Both species are unique to Florida landscapes that are dominated by shrubs and grasses and maintained by frequent fires. Both species are declining, even in protected areas, despite their protected status. I mapped habitat for both species using grid polygon cells to quantify population potential and habitat quality. A grid cell was the average territory size and the landcover unit in which habitat-specific recruitment and survival occurred. I measured habitat-specific recruitment and survival of Florida Scrub-Jays from 1988-2008. Data analyses included multistate analysis, which was developed for capture-recapture data but is useful for analyzing many ecological processes, such as habitat change. I relied on publications by other investigators for empirical Florida Grasshopper Sparrow data. The amount of potential habitat was greatly underestimated by landcover mapping not specific to Florida Scrub-Jays. Overlaying east central Florida with grid polygons was an efficient method to map potential habitat and monitor habitat quality directly related to recruitment, survival, and management needs. Most habitats for both species were degraded by anthropogenic reductions in fire frequency. Degradation occurred across large areas. Florida Scrub-Jay recruitment and survival were most influenced by shrub height states. Multistate modeling of shrub heights showed that state transitions were influenced by vegetation composition, edges, and habitat management. Measured population declines of 4% per year corroborated habitat-specific modeling predictions. Habitat quality improved over the study period but not enough to recover precariously small populations. The degree of landcover fragmentation influenced mean Florida Scrub-Jay dispersal distances but not the number of occupied territories between natal and breeding territories. There was little exchange between populations, which were usually further apart than mean dispersal distances. Florida Scrub-Jays bred or delayed breeding depending on age, sex, and breeding opportunities. I show an urgent need also for Florida Grasshopper Sparrow habitat restoration given that the endangered bird has declined to only two sizeable populations and there is a high likelihood for continued large decline. A major effect of habitat fragmentation identified in this dissertation that should apply to many organisms in disturbance prone systems is that fragmentation disrupts natural processes, reducing habitat quality across large areas. Humans have managed wildland fire for > 40,000 years, so it should be possible to manage habitat for many endangered species that make Florida's biodiversity unique. This dissertation provides methods to quantify landscape units into potential source and sink territories and provides a basis for applying adaptive management to reach population and conservation goals.
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Date Issued: 2009
Identifier: CFE0002537, ucf:47638
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002537

Title: SIGNAL PROCESSING OF AN ECG SIGNALIN THE PRESENCE OF A STRONG STATIC MAGNETIC FIELD.
Creator: Gupta, Aditya, Weeks, Arthur, University of Central Florida
Abstract / Description: This dissertation addresses the problem of elevation of the T wave of an electrocardiogram (ECG) signal in the magnetic resonance imaging (MRI). In the MRI, due to the strong static magnetic field the interaction of the blood flow with this strong magnetic field induces a voltage in the body. This voltage appears as a superimposition at the locus of the T wave of the ECG signal. This looses important information required by the doctors to interpret the ST segment of the ECG and detect...
Show moreThis dissertation addresses the problem of elevation of the T wave of an electrocardiogram (ECG) signal in the magnetic resonance imaging (MRI). In the MRI, due to the strong static magnetic field the interaction of the blood flow with this strong magnetic field induces a voltage in the body. This voltage appears as a superimposition at the locus of the T wave of the ECG signal. This looses important information required by the doctors to interpret the ST segment of the ECG and detect diseases such as myocardial infarction. This dissertation aims at finding a solution to the problem of elevation of the T wave of an ECG signal in the MRI. The first step is to simulate the entire situation and obtain the magnetic field dependent T wave elevation. This is achieved by building a model of the aorta and simulating the blood flow in it. This model is then subjected to a static magnetic field and the surface potential on the thorax is measured to observe the T wave elevation. The various parameters on which the T wave elevation is dependent are then analyzed. Different approaches are used to reduce this T wave elevation problem. The direct approach aims at computing the magnitude of T wave elevation using magneto-hydro-dynamic equations. The indirect approach uses digital signal processing tools like the least mean square adaptive filter to remove the T wave elevation and obtain artifact free ECG signal in the MRI. Excellent results are obtained from the simulation model. The model perfectly simulates the ECG signal in the MRI at all the 12 leads of the ECG. These results are compared with ECG signals measured in the MRI. A simulation package is developed in MATLAB based on the simulation model. This package is a graphical user interface allowing the user to change the strength of magnetic field, the radius of the aorta and the orientation of the aorta with respect to the heart and observe the ECG signals with the elevation at the 12 leads of the ECG. Also the artifacts introduced due to the magnetic field can be removed by the least mean square adaptive filter. The filter adapts the ECG signal in the MRI to the ECG signal of the patient outside the MRI. Before the adaptation, the heart rate of the ECG outside the MRI is matched to the ECG in the MRI by interpolation or decimation. The adaptive filter works excellently to remove the T wave artifacts. When the cardiac output of the patient changes, the simulation model is used along with the adaptive filter to obtain the artifact free ECG signal.
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Date Issued: 2007
Identifier: CFE0001857, ucf:47389
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001857

Title: SELF-ASSEMBLED LIPID TUBULES: STRUCTURES, MECHANICAL PROPERTIES, AND APPLICATIONS.
Creator: Zhao, Yue, Fang, Jiyu, University of Central Florida
Abstract / Description: Self-assembled lipid tubules are particularly attractive for inorganic synthesis and drug delivery because they have hollow cylindrical shapes and relatively rigid mechanical properties. In this thesis work, we have synthesized lipid tubules of 1,2-bis(tricosa-10,12-dinoyl)-sn-glycero-3-phosphocholine (DC8,9PC) by self-assembly and polymerization in solutions. We demonstrate for the first time that both uniform and modulated molecular tilt orderings exist in the tubule walls, which have been...
Show moreSelf-assembled lipid tubules are particularly attractive for inorganic synthesis and drug delivery because they have hollow cylindrical shapes and relatively rigid mechanical properties. In this thesis work, we have synthesized lipid tubules of 1,2-bis(tricosa-10,12-dinoyl)-sn-glycero-3-phosphocholine (DC8,9PC) by self-assembly and polymerization in solutions. We demonstrate for the first time that both uniform and modulated molecular tilt orderings exist in the tubule walls, which have been predicted by current theories, and therefore provide valuable supporting evidences for self-assembly mechanisms of chiral molecules. Two novel methods are developed for studying the axial and radial deformations of DC8,9PC lipid tubules. Mechanical properties of DC8,9PC tubules are systematically studied in terms of persistence length, bending rigidity, strain energy, axial and radial elastic moduli, and critical force for collapse. Mechanisms of recovery and surface stiffening are discussed. Due to the high aspect ratio of lipid tubules, the hierarchical assembly of lipid tubules into ordered arrays and desired architectures is critical in developing their applications. Two efficient methods for fabricating ordered arrays of lipid tubules on solid substrates have been developed. Ordered arrays of hybrid silica-lipid tubes are synthesized by tubule array-templated sol-gel reactions. Ordered arrays of optical anisotropic fibers with tunable shapes and refractive indexes are fabricated. This thesis work provides a paradigm for molecularly engineered structures.
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Date Issued: 2007
Identifier: CFE0001918, ucf:47486
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001918

Title: THE NATURE OF AND IMPORTANCE OF ART CRITICISM AND ITS EDUCATIONAL APPLICATIONS IN K-12 CLASSROOMS.
Creator: Blackmon, Tia, Brewer, Thomas, University of Central Florida
Abstract / Description: This thesis will critically examine the importance, purpose, methods, and applications of art criticism. Initial background information on types of critical judgment will lay the foundation to understanding the different methods of art criticism. While the articles and journals read on criticism vary in style and method they all have the goal to become a basic framework for examining the form and content of works of art. My goal of this thesis will be to take researched methods of criticism...
Show moreThis thesis will critically examine the importance, purpose, methods, and applications of art criticism. Initial background information on types of critical judgment will lay the foundation to understanding the different methods of art criticism. While the articles and journals read on criticism vary in style and method they all have the goal to become a basic framework for examining the form and content of works of art. My goal of this thesis will be to take researched methods of criticism and create my own methods of criticism to be used in the K-12 art education classroom. The body of my research will examine the following methods of criticism (1) Feldman Method, (2) Broudy Method, (3) Lankford Method, (4) Anderson Method, (5) Feminist Conversation Method, (6) Modernism, and (7) Postmodernism. My research will seek to understand the nature of and importance of art criticism and its educational applications for K-12 art classrooms. In conjunction with the examination of these methods and their corresponding stages, I will be able to synthesize three methods of criticism to be used in the classroom: formalist, expressivist, and instrumentalist.
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Date Issued: 2015
Identifier: CFH0004863, ucf:45465
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004863

Title: COHABITATION: LOOKING THROUGH A KEYHOLE.
Creator: Torrecampo, Mary Joy, Poindexter, Carla, University of Central Florida
Abstract / Description: Initially, my developing body of work aimed to redesign the traditions of representational painting, specifically the female nude, to depict the contemporary notions of lesbianism and femininity in an honest and empowering manner as a form of identity and not as vehicle for voyeurism. As an artist who paints the female nude and identifies as a woman and a lesbian, I examine the preexisting notions of the male gaze and the effect of socialization as it pertains to my work. The act of looking...
Show moreInitially, my developing body of work aimed to redesign the traditions of representational painting, specifically the female nude, to depict the contemporary notions of lesbianism and femininity in an honest and empowering manner as a form of identity and not as vehicle for voyeurism. As an artist who paints the female nude and identifies as a woman and a lesbian, I examine the preexisting notions of the male gaze and the effect of socialization as it pertains to my work. The act of looking from the point of view of a woman, which is not synonymous with a "female gaze", or from the point of view of a lesbian, is not a birthright, but a conscious effort to constantly question the way we see and produce pictures and realizing that the male gaze permeates most images of female nudes. By the nature of my sexuality and my exposure to existing male-produced images, do I see the female nude through the male gaze or is there a gaze that is essentially female? Does it matter either way if the image is aesthetically compelling? My paintings neither attempt to conform to the male gaze or debunk it, nor do I attempt to prove the existence of a female gaze. Like Edgar Degas, I wish to look through a keyhole - a form of voyeurism - to see people outside of their public facade.
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Date Issued: 2014
Identifier: CFH0004713, ucf:45402
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004713

Title: NOT REALLY BOLLYWOOD:A HISTORY OF POPULAR HINDI FILMS, SONGS, AND DANCE WITH PEDAGOGICAL APPLICATIONS FOR UNDERSTANDING INDIAN HISTORY AND CULTURE.
Creator: Nayee, Sanjana, Kaplan, Jeffrey, University of Central Florida
Abstract / Description: Contemporary fascination with 'Bollywood' proliferates much of reality TV dance shows, media blurbs and other communicative outlets. These avenues homogenize India as 'Bollywood', while social and political outlets place Indians and people of South Asian descent into fitted stereotypes that are ridiculed and largely distorted. The intent of this thesis was to explore how the growing international intrigues of popular Hindi films exist beyond 'Bollywood'. This study is especially important...
Show moreContemporary fascination with 'Bollywood' proliferates much of reality TV dance shows, media blurbs and other communicative outlets. These avenues homogenize India as 'Bollywood', while social and political outlets place Indians and people of South Asian descent into fitted stereotypes that are ridiculed and largely distorted. The intent of this thesis was to explore how the growing international intrigues of popular Hindi films exist beyond 'Bollywood'. This study is especially important because current U.S. demographics are undergoing a 'browning' effect yet a comprehensive method for understanding South Asian peoples and their cultures have been isolated to terrorist 'breeders', the model minority or as products primed for consumption. This thesis discusses the history of popular Hindi popular cinema, its changing methods of songs and dance and includes options of pedagogical applications within secondary level classrooms. In short, this thesis is an effort to highlight the similarities present amongst the differences that are consciously and unconsciously created or implicitly believed by the general population when attempting to decipher the many different components that exist across South Asian cultures, ethnicities, traditions, histories and identities.
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Date Issued: 2012
Identifier: CFH0004309, ucf:45055
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004309

Title: CHARACTERIZATION OF POLYETHERIMIDE UNDER STATIC, DYNAMIC, AND MULTIPLE IMPACT CONDITIONS.
Creator: Zuanetti, Bryan, Gordon, Ali, University of Central Florida
Abstract / Description: The application of polymers in robust engineering designs is on the rise due to their excellent mechanical properties such as high fracture toughness, specific strength, durability, as well as, thermal and chemical resistances. Implementation of some advanced polymeric solids is limited due to the lack of available mechanical properties. In order for these materials to endure strenuous engineering designs it is vital to investigate their response in multiple loading rates and conditions. In...
Show moreThe application of polymers in robust engineering designs is on the rise due to their excellent mechanical properties such as high fracture toughness, specific strength, durability, as well as, thermal and chemical resistances. Implementation of some advanced polymeric solids is limited due to the lack of available mechanical properties. In order for these materials to endure strenuous engineering designs it is vital to investigate their response in multiple loading rates and conditions. In this thesis, the mechanical response of polyethermide (PEI) is characterized under quasi-static, high strain rate, and multiple impact conditions. Standard tension, torsion, and compression experiments are performed in order to distinguish the multi-regime response of PEI. The effects of physical ageing and rejuvenation on the quasi-static mechanical response are investigated. The strain softening regime resulting from strain localization is eliminated by thermal and mechanical rejuvenation, and the advantages of these processes are discussed. The dynamic fracture toughness of the material in response to notched impact via Charpy impact test is evaluated. The high strain-rate response of PEI to uniaxial compression is evaluated at rates exceeding 104/s via miniaturized Split Hopkinson Pressure Bar (MSHPB), and compared to the quasi-static case to determine strain-rate sensitivity. The elastic response of the aged material to multiple loading conditions are correlated using the Ramberg-Osgood equation, while the elastoplastic response of rejuvenated PEI is correlated using a both the Ramberg-Osgood equation and a novel model. The strain-rate sensitivity of the strength is found to be nominally bilinear and transition strains are modeled using the Ree-Erying formulation. Finally, multiple impact experiments are performed on PEI using the MSHPB and a model is proposed to quantify damage as a result of collision.
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Date Issued: 2013
Identifier: CFH0004531, ucf:45166
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFH0004531

Title: NATIVE FIRE REGIME AS A REFERENCE FOR ESTABLISHING MANAGEMENT PRACTICES.
Creator: Duncan, Brean, Weishampel, John, University of Central Florida
Abstract / Description: Our understanding of natural fire regimes in human-dominated landscapes is limited. Fire regimes operating in the pyrogenic ecosystems of Florida have been altered by fire suppression and fuel fragmentation. This is especially true of North Merritt Island, Florida, where human impacts have led to an incomplete knowledge of current fire regimes. We know that growing season fires frequently occurred within general return intervals and that many native terrestrial species require fire to remain...
Show moreOur understanding of natural fire regimes in human-dominated landscapes is limited. Fire regimes operating in the pyrogenic ecosystems of Florida have been altered by fire suppression and fuel fragmentation. This is especially true of North Merritt Island, Florida, where human impacts have led to an incomplete knowledge of current fire regimes. We know that growing season fires frequently occurred within general return intervals and that many native terrestrial species require fire to remain viable. A 20-year plus period of fire suppression caused structural and compositional changes to vegetation/fuels that led to catastrophic fires and the decline of native species populations such as the Florida Scrub-Jay. Fire has been reintroduced as a means to reduce fuels and maintain habitat requirements for native species. Scientific studies have documented the effects and benefits of prescribed burning on KSC/MINWR habitat/fuels structure. The necessity for fire to maintain vegetation/fuels structure and composition on the landscape is clear so fire is being applied to the landscape despite our imperfect knowledge of the native fire regime. It is imperative for the survival of many native species that fire managers be able to mimic the results of the native fire regime. Fire regime research is difficult in shrublands, and using dendrochronologic techniques are often not possible in flatwoods communities. I therefore used a process of remote sensing, GIS mapping, and spatial modeling to quantify lightning fire ignition properties, the current managed fire regime, and the natural fire regime. Chapter one develops a new remote sensing technique to accurately map burned areas in Florida scrub and pine flatwoods dominated communities on Kennedy Space Center, Merritt Island National Wildlife Refuge, Canaveral National Seashore, and Cape Canaveral Air Force Station, Florida. At the center of this technique is a newly developed separation index (SI) that was used to evaluate each individual satellite image band for its power to discriminate unburned and burned areas. Burned areas were classified and found to be highly accurate in relation to empirical fire records. This chapter addressed a number of issues relevant to the classification of burned areas including: the effect of geographic extent of remote sensing data on classification, determining the best bands for classification, and cleaning classification results by using GIS masking. It also serves as the first published effort to map fire scars in the Florida scrub and flatwoods vegetative communities of the southeastern U.S. using image processing techniques. Chapter two quantified a managed fire regime on John F. Kennedy Space Center, Florida and surrounding federal properties by mapping all fires between 1983 to 2005 using the image processing technique developed in chapter one, time series satellite imagery, and GIS techniques. The goals were to: (1) determine if an image processing technique designed for individual fire scar mapping could be applied to an image time series for mapping a managed fire regime in a rapid re-growth pyrogenic system; (2) develop a method for labeling mapped fire scar confidence knowing that a formal accuracy analysis was not possible; and (3) compare results of the managed fire regime with regional information on natural fire regimes to look for similarities/differences that might help optimize management for persistence of native fire-dependent species. The area burned by managed fire peaked when the drought index was low and was reduced when the drought index was high. This contrasts with the expectations regarding the natural fire regime of this region. Chapter three quantified the natural lightning ignition regime on Kennedy Space Center, Merritt Island National Wildlife Refuge, Canaveral National Seashore, and Cape Canaveral Air Force Station, Florida. Lightning is the natural ignition source in Florida, substantiating the need for understanding lightning fire incidence. Sixteen years of lightning data (1986-2003, excluding 1987 and 2002 due to missing data) from the NASA Cloud to Ground Lightning Surveillance System and fire ignition records were used to quantify the relationship between lightning incidence and fire ignition. Precipitation influenced the efficiency of lightning ignitions, particularly July precipitation. Negative polarity strikes caused the majority of ignitions. Pine flatwoods was ignited more frequently than expected given equal chance of ignition among landcover types. About half (51%) of detected fires were instantaneous ignitions and the other 49% were delayed an average of two days. Summer lightning ignitions were dominant, especially during July, with only one winter lightning ignition. Chapter four used an existing fire regime model (HFire) to simulate the natural fire regime (prior to European settlement) on Kennedy Space Center, Merritt Island National Wildlife Refuge, Canaveral National Seashore, and Cape Canaveral Air Force Station, Florida. A sensitivity analysis was performed to establish which parameters were most important and the range of variation surrounding empirically derived model information from the same model. A mosaic pattern of small fires dominated this fire regime with extremely large fires occurring during dry La Nina periods. Dead fuel moisture and wind speed had the largest influence on model outcome. The majority of variability was found to be in the largest fires. The research presenter here provides a comprehensive perspective on current and historic fire regimes that may be useful for optimizing land management on Kennedy Space Center, Merritt Island National Wildlife Refuge, Canaveral National Seashore, and Cape Canaveral Air Force Station, Florida and throughout the southeastern United States. Native fire dependent species are suffering from many changes imposed from human alteration. The success of conservation efforts protecting native fire dependent species hinge on my factors. Two of the largest factors are first protecting native habitat and then secondly managing that protected habitat to mimic natural maintenance processes for suitable structure and composition which may favor their demography. This study focuses on developing techniques necessary for producing information that can aid the optimization of fire management on these properties and within the southeastern United States, but may be useful in other fire maintained ecosystems globally.
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Date Issued: 2009
Identifier: CFE0002862, ucf:48051
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002862

Title: THE CALIBRATION AND VERIFICATION OF SIMULATION MODELS FOR TOLL PLAZAS.
Creator: Russo, Christopher, Radwan, Essam, University of Central Florida
Abstract / Description: A great deal of research has been conducted on Central Florida toll roads to better understand the characteristics of the tolling operation. In this thesis, the development and calibration of a toll plaza simulation models will be analyzed using two simulation programs varying mostly in their modeling theory. The two models utilized are, SHAKER, a deterministic queuing model for vehicles utilizing toll collection facilities, and VISSIM, a globally popular stochastic simulation software. The...
Show moreA great deal of research has been conducted on Central Florida toll roads to better understand the characteristics of the tolling operation. In this thesis, the development and calibration of a toll plaza simulation models will be analyzed using two simulation programs varying mostly in their modeling theory. The two models utilized are, SHAKER, a deterministic queuing model for vehicles utilizing toll collection facilities, and VISSIM, a globally popular stochastic simulation software. The benefits of simulation models leads to the purpose of this thesis, which is to examine the effectiveness of two toll modeling programs that are similar in purpose but vary in approach and methodology. Both SHAKER and VISSIM toll plaza models have the potential to work as a tool that can estimate the maximum throughput and capacity of toll plazas. Major operational benefits resulting from developing these models are to simulate and evaluate how traffic conditions will change when demand increases, when and if queues increase when a lane is closed due to maintenance or construction, the impact of constructing additional lanes, or determining whether or not the best lane type configuration is currently implemented. To effectively calibrate any model available site data must be used to compare simulation results to for model validity. In an effort to correctly calibrate the SHAKER toll plaza tool and VISSIM model, an extensive field collection procedure was conducted at four Florida Turnpike operated toll facilities located in Central Florida. Each site differed from the others in terms of number of lanes, lane configuration, toll base fee, highway location, traffic demand, and vehicle percentage. The sites chosen for data collection were: the Lake Jesup Mainline Plaza along the Seminole Expressway (SR-417), the Beachline West Expressway Toll Plaza along the SR-528, the Daniel Webster Western Beltway Plaza along SR-429, and the Leesburg Toll Plaza along the Florida Turnpike Mainline SR-91. Upon completion of calibration of the two simulation models it is determined that each of the two software are successful in modeling toll plaza capacity and queuing. As expected, each simulation model does possess benefits over the other in terms of set up time, analysis reporting time, and practicality of results. The SHAKER model setup takes mere seconds in order to create a network and input vehicle, another few seconds to calibrate driving parameters, and roughly 10 additional seconds to report analysis. Conversely, setting up the VISSIM model, even for the most experienced user, can take several hours and the report analysis time can take several more hours as it is dependant on the number of required simulation runs and complexity of the network. VISSIM is most beneficial by the fact that its modeling allows for driver variability while SHAKER assumes equilibrium amongst lane choice and queuing. This creates a more realistic condition to observed traffic patterns. Even though differences are prevalent, it is important that in each simulation model the capacity is accurately simulated and each can be used to benefit operational situations related to toll plaza traffic conditions.
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Date Issued: 2008
Identifier: CFE0002376, ucf:47821
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002376

Title: A Joint Econometric Approach for Modeling Crash Counts by Collision Type.
Creator: Bhowmik, Tanmoy, Eluru, Naveen, Abdel-Aty, Mohamed, Yasmin, Shamsunnahar, University of Central Florida
Abstract / Description: In recent years, there is growing recognition that common unobserved factors that influence crash frequency by one attribute level are also likely to influence crash frequency by other attribute levels. The most common approach employed to address the potential unobserved heterogeneity in safety literature is the development of multivariate crash frequency models. The current study proposes an alternative joint econometric framework to accommodate for the presence of unobserved heterogeneity ...
Show moreIn recent years, there is growing recognition that common unobserved factors that influence crash frequency by one attribute level are also likely to influence crash frequency by other attribute levels. The most common approach employed to address the potential unobserved heterogeneity in safety literature is the development of multivariate crash frequency models. The current study proposes an alternative joint econometric framework to accommodate for the presence of unobserved heterogeneity (-) referred to as joint negative binomial-multinomial logit fractional split (NB-MNLFS) model. Furthermore, the study undertakes a first of its kind comparison exercise between the most commonly used multivariate model (multivariate random parameter negative binomial model) and the proposed joint approach by generating an equivalent log-likelihood measure. The empirical analysis is based on the zonal level crash count data for different collision types from the state of Florida for the year 2015. The model results highlight the presence of common unobserved effects affecting the two components of the joint model as well as the presence of parameter heterogeneity. The equivalent log-likelihood and goodness of fit measures clearly highlight the superiority of the proposed joint model over the commonly used multivariate approach.
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Date Issued: 2018
Identifier: CFE0007392, ucf:52740
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007392

Title: Streamflow prediction in ungauged basins located within data-scarce regions.
Creator: Alipour, Mohammadhossein, Kibler, Kelly, Wang, Dingbao, Mayo, Talea, Emrich, Christopher, University of Central Florida
Abstract / Description: Preservation and or restoration of riverine ecosystem requires quantification of alterations inflicted by water resources development projects. Long records of streamflow data are the first piece of information required in order to enable this analysis. Ungauged catchments located within data-scarce regions lack long records of streamflow data. In this dissertation, a multi-objective framework named Streamflow Prediction under Extreme Data-scarcity (SPED) is proposed for streamflow prediction...
Show morePreservation and or restoration of riverine ecosystem requires quantification of alterations inflicted by water resources development projects. Long records of streamflow data are the first piece of information required in order to enable this analysis. Ungauged catchments located within data-scarce regions lack long records of streamflow data. In this dissertation, a multi-objective framework named Streamflow Prediction under Extreme Data-scarcity (SPED) is proposed for streamflow prediction in ungauged catchments located within large-scale regions of minimal hydrometeorologic observation. Multi-objective nature of SPED allows for balancing runoff efficiency with selection of parameter values that resemble catchment physical characteristics. Uncertain and low-resolution information are incorporated in SPED as soft data along with sparse observations. SPED application in two catchments in southwestern China indicates high runoff efficiency for predictions and good estimation of soil moisture capacity in the catchments. SPED is then slightly modified and tested more comprehensively by application to six catchments with diverse hydroclimatic conditions. SPED performance proves satisfactory where traditional flow prediction approaches fail. SPED also proves comparable or even better than data-intensive approaches. Utility of SPED versus a simpler catchment similarity model for the study of flow regime alteration is pursued next by streamflow prediction in 32 rivers in southwestern China. The results indicate that diversion adversely alters the flow regime of the rivers while direction and pattern of change remain the same regardless of the flow prediction method of choice. However, the results based on SPED consistently indicate more substantial alterations to the flow regime of the rivers after diversion. Finally, the value added by a limited number of streamflow observations to improvement of predictions in an ungauged catchment located within a data-scarce region is studied. The large number of test scenarios indicate that there may be very few near-universal schemes to improve flow predictions in such catchments.
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Date Issued: 2019
Identifier: CFE0007426, ucf:52713
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007426

Title: Dissecting the Components of Neuropathic Pain.
Creator: George, Dale, Lambert, Stephen, Kim, Yoon-Seong, Fernandez-Valle, Cristina, Ebert, Steven, University of Central Florida
Abstract / Description: Pain is a public health issue affecting the lives of nearly 116 million adults in the US, annually. Understanding the physiological and phenotypic changes that occur in response to painful stimuli is of tremendous clinical interest, but, the complexity of pain and the lack of a representative in vitro model hinders the development of new therapeutics. Pain stimuli are first perceived and transmitted by the neurons within the dorsal root ganglia (DRG) which become hyperexcitable under these...
Show morePain is a public health issue affecting the lives of nearly 116 million adults in the US, annually. Understanding the physiological and phenotypic changes that occur in response to painful stimuli is of tremendous clinical interest, but, the complexity of pain and the lack of a representative in vitro model hinders the development of new therapeutics. Pain stimuli are first perceived and transmitted by the neurons within the dorsal root ganglia (DRG) which become hyperexcitable under these conditions. It has now been established that satellite glial cells (SGCs) that ensheathe the DRG cell body actively contribute to this neuronal dysregulation. To understand the role of SGCs in this pain circuit, first, we looked at the development of SGCs within the DRG of rats, and we showed that SGCs developed postnatally, and appeared morphologically, transcriptionally and functionally similar to Schwann cells precursors (SCs), supporting the idea that these cells may exhibit multipotent behavior. Secondly, we describe here, a three-dimensional in vitro model of the DRG which is functionally characterized on a microelectrode array (MEA). This model can be used to assess the long-term recording of spontaneous activity from bundles of axons while preserving the neuronal-SGC interactions similar to those observed in vivo. Furthermore, using capsaicin, an agonist of the TRPV1 nociceptive receptor, we show that this model can be used as an in vitro assay to acquire evoked responses from nociceptive neurons. Overall, this study advances our knowledge on the development and differentiation of SGCs and establishes a novel functional three-dimensional model for the study of SGCs. This model can now be used as a tool to study the underlying basis of neuronal dysregulation in pain.
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Date Issued: 2018
Identifier: CFE0007002, ucf:52053
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007002

Title: The Effect of Registered Nurse Supply on Population Health Outcomes: A Distributed Lag Model Approach.
Creator: Sampson, Carla Jackie, Unruh, Lynn, Malvey, Donna, Liu, Albert Xinliang, Neff, Donna, University of Central Florida
Abstract / Description: Registered nurses (RNs) are essential to providing care in the healthcare system. To date, research on the relationship between healthcare provider supply and population health has focused on physician supply. This study explored the effect of RN supply on population health outcomes in the U.S. This is a retrospective, cross-sectional study of U.S. counties and county equivalents using national data. Seven population health outcomes (total and disease specific mortalities and low infant birth...
Show moreRegistered nurses (RNs) are essential to providing care in the healthcare system. To date, research on the relationship between healthcare provider supply and population health has focused on physician supply. This study explored the effect of RN supply on population health outcomes in the U.S. This is a retrospective, cross-sectional study of U.S. counties and county equivalents using national data. Seven population health outcomes (total and disease specific mortalities and low infant birth weight rate) were the response variables. The predictor variable, RN supply, and some control variables were anticipated to have an asynchronous effect on the seven outcome variables in the hypothesized relationship. Therefore, these variables were examined using three different models: contemporaneous; a three-year lagged; and a distributed lag (both contemporaneous and lagged variables). Quadratic terms for RN and physician supply variables were included. Because the Area Health Resource File (AHRF) outcome variables were skewed toward zero and left censored, Tobit regression analyses were used. Data were obtained from 19 states using historical RN Supply data for 1,472 counties, representing 47% of the total target population of 3,108 U.S. counties and county equivalents. Regions with rural populations(-)the Midwest and Southeast(-)were overrepresented. Higher RN supply is positively related to higher mortality rates from ischemic heart disease, other cardiovascular disease, and chronic lower respiratory disease in the distributed lag models. Higher RN supply is not significantly related to rates of low infant birth weight, infant mortality, or mortality from cerebrovascular disease in any model. Higher RN supply is positively related to total deaths in the contemporaneous and lagged model. The results suggest a counter-intuitive, but non-linear relationship between RN supply and health outcomes. More research is needed to understand these relationships and policies must be devised to reduce the current and growing future RN shortage.
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Date Issued: 2018
Identifier: CFE0007091, ucf:51933
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007091

Title: Hybrid Multi-Objective Optimization of Left Ventricular Assist Device Outflow Graft Anastomosis Orientation to Minimize Stroke Rate.
Creator: Lozinski, Blake, Kassab, Alain, Mansy, Hansen, DeCampli, William, University of Central Florida
Abstract / Description: A Left Ventricular Assist Device (LVAD) is a mechanical pump that is utilized as a bridge to transplantation for patients with a Heart Failure (HF) condition. More recently, LVADs have been also used as destination therapy and have provided an increase in the quality of life for patients with HF. However, despite improvements in VAD design and anticoagulation treatment, there remains a significant problem with VAD therapy, namely drive line infection and thromboembolic events leading to...
Show moreA Left Ventricular Assist Device (LVAD) is a mechanical pump that is utilized as a bridge to transplantation for patients with a Heart Failure (HF) condition. More recently, LVADs have been also used as destination therapy and have provided an increase in the quality of life for patients with HF. However, despite improvements in VAD design and anticoagulation treatment, there remains a significant problem with VAD therapy, namely drive line infection and thromboembolic events leading to stroke. This thesis focuses on a surgical maneuver to address the second of these issues, guided by previous steady flow hemodynamic studies that have shown the potential of tailoring the VAD outflow graft (VAD-OG) implantation in providing up to 50% reduction in embolization rates. In the current study, multi-scale pulsatile hemodynamics of the VAD bed is modeled and integrated in a fully automated multi-objective shape optimization scheme in which the VAD-OG anastomosis along the Ascending Aorta (AA) is optimized to minimize the objective function which include thromboembolic events to the cerebral vessels and wall shear stress (WSS). The model is driven by a time dependent pressure and flow boundary conditions located at the boundaries of the 3D domain through a 50 degree of freedom 0D lumped parameter model (LPM). The model includes a time dependent multi-scale Computational Fluid Dynamics (CFD) analysis of a patient specific geometry. Blood rheology is modeled as using the non-Newtonian Carreua-Yasuda model, while the hemodynamics are that of a laminar and constant density fluid. The pulsatile hemodynamics are resolved using the commercial CFD solver StarCCM+ while a Lagrangian particle tracking scheme is used to track constant density particles modeling thromobi released from the cannula to determine embolization rated of thrombi. The results show that cannula anastomosis orientation plays a large role when minimizing the objective function for patient derived aortic bed geometry used in this study. The scheme determined the optimal location of the cannula is located at 5.5 cm from the aortic root, cannula angle at 90 degrees and coronal angle at 8 degrees along the AA with a peak surface average WSS of 55.97 dy/cm2 and stroke percentile of 12.51%. A Pareto front was generated showing the range of 9.7% to 44.08% for stroke and WSS of 55.97 to 81.47 dy/cm2 ranged over 22 implantation configurations for the specific case studied. These results will further assist in the treatment planning for clinicians when implementing a LVAD.
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Date Issued: 2019
Identifier: CFE0007833, ucf:52827
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007833

Title: An Investigation of College Student-Athletes' Mental Health Stigma, Help-Seeking Attitudes, Depression, Anxiety, and Life Stress Scores Using Structural Equation Modeling.
Creator: Tabet, Saundra, Lambie, Glenn, Barden, Sejal, Taylor, Dalena, Wood, Eric, Jahani, Shiva, University of Central Florida
Abstract / Description: The purpose of this study was to investigate the directional relationship between student-athletes' degree of mental health stigma, help-seeking attitudes, depression, anxiety, and life stress scores. This investigation tested the theoretical model that student-athletes' (N = 621) degree of mental health stigma (as measured by the Perceived Devaluation-Discrimination Scale (-) Adapted [PDD-A; Eisenberg et al., 2009]) contributed to their attitudes towards help-seeking (as measured by the...
Show moreThe purpose of this study was to investigate the directional relationship between student-athletes' degree of mental health stigma, help-seeking attitudes, depression, anxiety, and life stress scores. This investigation tested the theoretical model that student-athletes' (N = 621) degree of mental health stigma (as measured by the Perceived Devaluation-Discrimination Scale (-) Adapted [PDD-A; Eisenberg et al., 2009]) contributed to their attitudes towards help-seeking (as measured by the Attitudes Toward Seeking Professional Psychological Help (-) Short Form [ATSPPH-SF; Fisher (&) Farina, 1995]) and levels of depression (as measured by the Patient Health Questionnaire (-) 9 [PHQ-9; Kroenke et al., 2001]), anxiety (as measured by the Generalized Anxiety Disorder - 7 [GAD-7; Spitzer et al., 2006]), and life stress (as measured by the College Student-Athlete Life Stress Scale [CSALSS; Lu et al., 2012]). Specifically, the researcher tested the hypothesized directional relationship that student-athletes with a greater amount of mental health stigma would have (a) decreased positive help-seeking attitudes and (b) increased levels of depression, anxiety, and life stress. The results of the structural equation model (SEM) analyses identified that student-athletes' amount of mental health stigma contributed to help-seeking attitudes (25.6% of the variance), but not levels of depression (.16% of the variance), anxiety (.09% of the variance), or life stress (.81% of the variance). Specifically, student-athletes' degree of mental health stigma shared a strong negative relationship (-.506) with attitudes towards seeking professional psychological help. Further, the results identified that personal stigma mediates the relationship between public stigma and help-seeking attitudes. Implications of the findings include (a) greater knowledge of the importance student-athletes' mental health stigma and attitudes toward receiving help; (b) increased understanding for counselors of student-athletes mental health needs; and (c) insight into practices for institutions of higher education as they implement mental health initiatives within intercollegiate athletics.
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Date Issued: 2019
Identifier: CFE0007538, ucf:52597
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007538

Title: Thermodynamic Modeling and Transient Simulation of a Low-Pressure Heat Recovery Steam Generator Using Siemens T3000.
Creator: Caesar, Andres, Das, Tuhin, Bhattacharya, Samik, Putnam, Shawn, University of Central Florida
Abstract / Description: With world energy consumption rising, and nonrenewable energy resources quickly depleting, it is essential to design more efficient power plants and thereby economically utilize fossil fuels. To that end, this work focuses on the thermodynamic modeling of steam power systems to enhance our understanding of their dynamic and transient behavior. This thesis discusses the physical phenomena behind a heat recovery steam generator (HRSG) and develops a mathematical description of its system...
Show moreWith world energy consumption rising, and nonrenewable energy resources quickly depleting, it is essential to design more efficient power plants and thereby economically utilize fossil fuels. To that end, this work focuses on the thermodynamic modeling of steam power systems to enhance our understanding of their dynamic and transient behavior. This thesis discusses the physical phenomena behind a heat recovery steam generator (HRSG) and develops a mathematical description of its system dynamics. The model is developed from fundamentals of fluid dynamics, phase change, heat transfer, conservation laws and unsteady flow energy equations. The resulting model captures coupled physical phenomena with acceptable accuracy while achieving fast, and potentially real-time, simulations. The computational HRSG model is constructed in the Siemens T3000 platform. This work establishes the dynamic modeling capability of T3000, which has traditionally been used for programming control algorithms. The validation objective of this project is to accurately simulate the transient response of an operational steam power system. Validation of the T3000 model is carried out by comparing simulation results to start-up data from the low-pressure system of a Siemens power plant while maintaining the same inlet conditions. Simulation results well correlate with plant data regarding transient behavior and equilibrium conditions. With a comprehensive HRSG model available, it will allow for further research to take place, and aid in the advancement of steam power system technology. Some future research areas include the extension to intermediate and high-pressure system simulations, combined simulation of all three pressure stages, and continued improvement of the boiler model. In addition to enabling model-based prediction and providing further insight, this effort will also lead to controller design for improved performance.
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Date Issued: 2018
Identifier: CFE0007562, ucf:52599
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007562

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