Current Search: modeling (x)
Pages
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Title
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Autoregressive Models.
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Creator
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Wade, William, Richardson, Gary, Pensky, Marianna, Li, Xin, University of Central Florida
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Abstract / Description
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Consider a sequence of random variables which obeys a first order autoregressive model with unknown parameter alpha. Under suitable assumptions on the error structure of the model, the limiting distribution of the normalized least squares estimator of alpha is discussed. The choice of the normalizing constant depends on whether alpha is less than one, equals one, or is greater than one in absolute value. In particular, the limiting distribution is normal provided that the absolute value of...
Show moreConsider a sequence of random variables which obeys a first order autoregressive model with unknown parameter alpha. Under suitable assumptions on the error structure of the model, the limiting distribution of the normalized least squares estimator of alpha is discussed. The choice of the normalizing constant depends on whether alpha is less than one, equals one, or is greater than one in absolute value. In particular, the limiting distribution is normal provided that the absolute value of alpha is less than one, but is a function of Brownian motion whenever the absolute value of alpha equals one. Some general remarks are made whenever the sequence of random variables is a first order moving average process.
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Date Issued
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2012
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Identifier
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CFE0004276, ucf:49546
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004276
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Title
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THREE DIMENSIONAL MODELING OF WEKIVA SPRINGSHED WITH WASH123D.
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Creator
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Paladagu, Sandeep, Gour-Tsyh, Yeh, University of Central Florida
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Abstract / Description
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This thesis presents a three-dimensional groundwater modeling of Wekia springshed in central Florida using a numerical model, WASH123D. Springs have historically played an important role in Florida's history. The Wekiva River is a spring-fed system associated with about 19 springs connected to the Floridan aquifer. With increased urbanization and population growth in this region, there has been an increased strain on the water levels of Floridan aquifer which is a major source of potable...
Show moreThis thesis presents a three-dimensional groundwater modeling of Wekia springshed in central Florida using a numerical model, WASH123D. Springs have historically played an important role in Florida's history. The Wekiva River is a spring-fed system associated with about 19 springs connected to the Floridan aquifer. With increased urbanization and population growth in this region, there has been an increased strain on the water levels of Floridan aquifer which is a major source of potable water. Maintaining groundwater recharge to the aquifer is a key factor of the viability of the regional water supply as well as Wekiva ecosystem. Hence, the first-principle, physics-based watershed model WASH123D has been applied to conduct the study of Wekiva "springshed", which is the recharge area and watershed contributing groundwater and surface water to the spring. In this work, the hydrogeologic conditions of the Wekiva springshed are discussed followed by the modeling details such as mathematical background, domain discretization and initial and boundary conditions considered. Finally, the results from the model are discussed. The Wekiva WASH123D model was run to evaluate the average, steady state 1995 hydrological conditions. The distribution of simulated Floridan aquifer system groundwater levels using WASH123D shows very good agreement with the field observations at corresponding locations.
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Date Issued
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2005
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Identifier
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CFE0000647, ucf:46530
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000647
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Title
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Modeling Network Worm Outbreaks.
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Creator
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Foley, Evan, Shuai, Zhisheng, Kaup, David, Nevai, A, University of Central Florida
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Abstract / Description
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Due to their convenience, computers have become a standard in society and therefore, need the utmost care. It is convenient and useful to model the behavior of digital virus outbreaks that occur, globally or locally. Compartmental models will be used to analyze the mannerisms and behaviors of computer malware. This paper will focus on a computer worm, a type of malware, spread within a business network. A mathematical model is proposed consisting of four compartments labeled as Susceptible,...
Show moreDue to their convenience, computers have become a standard in society and therefore, need the utmost care. It is convenient and useful to model the behavior of digital virus outbreaks that occur, globally or locally. Compartmental models will be used to analyze the mannerisms and behaviors of computer malware. This paper will focus on a computer worm, a type of malware, spread within a business network. A mathematical model is proposed consisting of four compartments labeled as Susceptible, Infectious, Treatment, and Antidotal. We shall show that allocating resources into treating infectious computers leads to a reduced peak of infections across the infection period, while pouring resources into treating susceptible computers decreases the total amount of infections throughout the infection period. This is assuming both methods are receiving resources without loss. This result reveals an interesting notion of balance between protecting computers and removing computers from infections, ultimately depending on the business executives' goals and/or preferences.
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Date Issued
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2015
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Identifier
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CFE0005948, ucf:50816
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0005948
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Title
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A MATHEMATICAL STUDY OF TWO RETROVIRUSES, HIV AND HTLV-I.
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Creator
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Baxley, Dana, Mohapatra, Ram, University of Central Florida
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Abstract / Description
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In this thesis, we examine epidemiological models of two different retroviruses, which infect the human body. The two viruses under study are HIV or the human immunodefiency virus and HTLV-I, which is the human T lymphotropic virus type I. A retrovirus is a virus, which injects its RNA into the host, rather than it's DNA. We will study each of the different mathematical models for each of the viruses separately. Then we use MATLAB-SIMULINK to analyze the models by studying the...
Show moreIn this thesis, we examine epidemiological models of two different retroviruses, which infect the human body. The two viruses under study are HIV or the human immunodefiency virus and HTLV-I, which is the human T lymphotropic virus type I. A retrovirus is a virus, which injects its RNA into the host, rather than it's DNA. We will study each of the different mathematical models for each of the viruses separately. Then we use MATLAB-SIMULINK to analyze the models by studying the reproductive numbers in each case and the disease progression by examining the graphs. In Chapter 1, we mention basic ideas associated with HIV and HTLV-I. In Chapter 2 some of the basic mathematical model of epidemiology is presented. Chapter 3 is devoted to a model describing the intra-host dynamics of HIV. Here, we take into account how HIV infects and replicates in the CD4+ T cells. The model studied in this thesis examines the difference between cells, which are susceptible to the virus, and cells, which are not susceptible. Through the graphs associated with this model, we are able to see how this difference affects disease progression. In Chapter 4, we examine the effect of HTLV-I virus on human body. The HTLV-I virus causes a chronic infection in humans and may eventually lead to other diseases. In particular, the development of Adult T-cell Leukemia or ATL is studied in this thesis. The T-cell dynamics and progression to ATL is described using a mathematical model with coupled differential equations. Using mathematical analysis and SIMULINK, we obtain results on stability, asymptotic stability and the manner of progression of the disease. In Chapter 5 and appendices, we mention our inference and the MATLAB-SIMULINK codes used in this thesis, so that a reader can verify the details of the work carried out in this thesis.
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Date Issued
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2007
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Identifier
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CFE0001886, ucf:47398
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0001886
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Title
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FRACTION MODELS THAT PROMOTE UNDERSTANDING FOR ELEMENTARY STUDENTS.
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Creator
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Hull, Lynette, Dixon, Juli, University of Central Florida
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Abstract / Description
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This study examined the use of the set, area, and linear models of fraction representation to enhance elementary students' conceptual understanding of fractions. Students' preferences regarding the set, area, and linear models of fractions during independent work was also investigated. This study took place in a 5th grade class consisting of 21 students in a suburban public elementary school. Students participated in classroom activities which required them to use manipulatives to represent...
Show moreThis study examined the use of the set, area, and linear models of fraction representation to enhance elementary students' conceptual understanding of fractions. Students' preferences regarding the set, area, and linear models of fractions during independent work was also investigated. This study took place in a 5th grade class consisting of 21 students in a suburban public elementary school. Students participated in classroom activities which required them to use manipulatives to represent fractions using the set, area, and linear models. Students also had experiences using the models to investigate equivalent fractions, compare fractions, and perform operations. Students maintained journals throughout the study, completed a pre and post assessment, participated in class discussions, and participated in individual interviews concerning their fraction model preference. Analysis of the data revealed an increase in conceptual understanding. The data concerning student preferences were inconsistent, as students' choices during independent work did not always reflect the preferences indicated in the interviews.
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Date Issued
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2005
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Identifier
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CFE0000552, ucf:46428
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000552
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Title
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MODELING PEDESTRIAN BEHAVIOR IN VIDEO.
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Creator
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Scovanner, Paul, Tappen, Marshall, University of Central Florida
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Abstract / Description
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The purpose of this dissertation is to address the problem of predicting pedestrian movement and behavior in and among crowds. Specifically, we will focus on an agent based approach where pedestrians are treated individually and parameters for an energy model are trained by real world video data. These learned pedestrian models are useful in applications such as tracking, simulation, and artificial intelligence. The applications of this method are explored and experimental results show that...
Show moreThe purpose of this dissertation is to address the problem of predicting pedestrian movement and behavior in and among crowds. Specifically, we will focus on an agent based approach where pedestrians are treated individually and parameters for an energy model are trained by real world video data. These learned pedestrian models are useful in applications such as tracking, simulation, and artificial intelligence. The applications of this method are explored and experimental results show that our trained pedestrian motion model is beneficial for predicting unseen or lost tracks as well as guiding appearance based tracking algorithms. The method we have developed for training such a pedestrian model operates by optimizing a set of weights governing an aggregate energy function in order to minimize a loss function computed between a model's prediction and annotated ground-truth pedestrian tracks. The formulation of the underlying energy function is such that using tight convex upper bounds, we are able to efficiently approximate the derivative of the loss function with respect to the parameters of the model. Once this is accomplished, the model parameters are updated using straightforward gradient descent techniques in order to achieve an optimal solution. This formulation also lends itself towards the development of a multiple behavior model. The multiple pedestrian behavior styles, informally referred to as "stereotypes", are common in real data. In our model we show that it is possible, due to the unique ability to compute the derivative of the loss function, to build a new model which utilizes a soft-minimization of single behavior models. This allows unsupervised training of multiple different behavior models in parallel. This novel extension makes our method unique among other methods in the attempt to accurately describe human pedestrian behavior for the myriad of applications that exist. The ability to describe multiple behaviors shows significant improvements in the task of pedestrian motion prediction.
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Date Issued
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2011
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Identifier
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CFE0004043, ucf:49146
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004043
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Title
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Bayesian Model Selection for Classification with Possibly Large Number of Groups.
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Creator
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Davis, Justin, Pensky, Marianna, Swanson, Jason, Richardson, Gary, Crampton, William, Ni, Liqiang, University of Central Florida
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Abstract / Description
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The purpose of the present dissertation is to study model selection techniques which are specifically designed for classification of high-dimensional data with a large number of classes. To the best of our knowledge, this problem has never been studied in depth previously. We assume that the number of components p is much larger than the number of samples n, and that only few of those p components are useful for subsequent classification. In what follows, we introduce two Bayesian models...
Show moreThe purpose of the present dissertation is to study model selection techniques which are specifically designed for classification of high-dimensional data with a large number of classes. To the best of our knowledge, this problem has never been studied in depth previously. We assume that the number of components p is much larger than the number of samples n, and that only few of those p components are useful for subsequent classification. In what follows, we introduce two Bayesian models which use two different approaches to the problem: one which discards components which have "almost constant" values (Model 1) and another which retains the components for which between-group variations are larger than within-group variation (Model 2). We show that particular cases of the above two models recover familiar variance or ANOVA-based component selection. When one has only two classes and features are a priori independent, Model 2 reduces to the Feature Annealed Independence Rule (FAIR) introduced by Fan and Fan (2008) and can be viewed as a natural generalization to the case of L (>) 2 classes. A nontrivial result of the dissertation is that the precision of feature selection using Model 2 improves when the number of classes grows. Subsequently, we examine the rate of misclassification with and without feature selection on the basis of Model 2.
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Date Issued
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2011
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Identifier
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CFE0004097, ucf:49091
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004097
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Title
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USING MODELING AND SIMULATION TO EVALUATE DISEASE CONTROL MEASURES.
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Creator
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Atkins, Tracy, Clarke, Thomas, University of Central Florida
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Abstract / Description
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This dissertation introduced several issues concerning the analysis of diseases by showing how modeling and simulation could be used to assist in creating health policy by estimating the effects of such policies. The first question posed was how would education, vaccination and a combination of these two programs effect the possible outbreak of meningitis on a college campus. After creating a model representative of the transmission dynamics of meningitis and establishing parameter values...
Show moreThis dissertation introduced several issues concerning the analysis of diseases by showing how modeling and simulation could be used to assist in creating health policy by estimating the effects of such policies. The first question posed was how would education, vaccination and a combination of these two programs effect the possible outbreak of meningitis on a college campus. After creating a model representative of the transmission dynamics of meningitis and establishing parameter values characteristic of the University of Central Florida main campus, the results of a deterministic model were presented in several forms. The result of this model was the combination of education and vaccination would eliminate the possibility of an epidemic on our campus. Next, we used simulation to evaluate how quarantine and treatment would affect an outbreak of influenza on the same population. A mathematical model was created specific to influenza on the UCF campus. Numerical results from this model were then presented in tabular and graphical form. The results comparing the simulations for quarantine and treatment show the best course of action would be to enact a quarantine policy on the campus thus reducing the maximum number of infected while increasing the time to reach this peak. Finally, we addressed the issue of performing the analysis stochastically versus deterministically. Additional models were created with the progression of the disease occurring by chance. Statistical analysis was done on the mean of 100 stochastic simulation runs comparing that value to the one deterministic outcome. The results for this analysis were inconclusive, as the results for meningitis were comparable while those for influenza appeared to be different.
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Date Issued
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2010
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Identifier
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CFE0003232, ucf:48535
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0003232
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Title
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An application of a computerized mathematical model for estimating the quantity and quality of nonpoint sources of pollution from small urban and nonurban watersheds.
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Creator
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Ingraham, Charles John, Wanielista, Martin P., Engineering
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Abstract / Description
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Florida Technological University College of Engineering Thesis; The problem of "Total Water Management" is reviewed; particular emphasis is given to the magnitude and intensity of pollution from nonpoint sources. The relationship between land usage in south Florida and subsequent effects upon receiving water bodies is discussed. Basic factors effecting hydrological and ecological subsystems are illustrated. The U.S. Army Corps of Engineers Urban Storm Water Runoff Mathematical Model, "STORM,"...
Show moreFlorida Technological University College of Engineering Thesis; The problem of "Total Water Management" is reviewed; particular emphasis is given to the magnitude and intensity of pollution from nonpoint sources. The relationship between land usage in south Florida and subsequent effects upon receiving water bodies is discussed. Basic factors effecting hydrological and ecological subsystems are illustrated. The U.S. Army Corps of Engineers Urban Storm Water Runoff Mathematical Model, "STORM," is introduced. Model parameters and methodology are discussed. The mathematical relationships and modeling processes are reviewed and the model is exercised using a "new generation" southeast Florida community (The City of Palm Beach Gardens) as the subject of study. It is concluded that the model can be beneficial in supporting estimates of pollutant loading to receiving waters from nonpoint sources. Iteration with the model, varying control facility cost and capacity, provides a cost effective tool for land and water resource planners. However, due to the particular nature of soils, atmospheric and urban conditions in south Florida, the model should be calibrated with input constants and default values derived to more accurately reflect the southeast Florida environment.
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Date Issued
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1975
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Identifier
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CFR0003515, ucf:53006
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFR0003515
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Title
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Personal Computer Simulation Program for Step Motor Drive Systems.
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Creator
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Koos, William M., Harden, Richard C., Engineering
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Abstract / Description
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University of Central Florida College of Engineering Thesis; A system of equations modeling a class of step motors known as the permanent magnet rotor step motor is presented. The model is implemented on a APPLE personal computer in a version of BASIC. Measurements are then made on an existing motor and input to the program for validation. A special test fixture is utilized to take performance data on the motor to facilitate comparisons with the predictions of the program. The comparisons...
Show moreUniversity of Central Florida College of Engineering Thesis; A system of equations modeling a class of step motors known as the permanent magnet rotor step motor is presented. The model is implemented on a APPLE personal computer in a version of BASIC. Measurements are then made on an existing motor and input to the program for validation. A special test fixture is utilized to take performance data on the motor to facilitate comparisons with the predictions of the program. The comparisons show the model is indeed valid for design of step motor drive systems and emphasize the practical nature of using personal computers and simulations for design
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Date Issued
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1982
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Identifier
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CFR0008163, ucf:53067
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFR0008163
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Title
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ANALYSIS AND INTEGRATION OF A DEBRIS MODEL IN THE VIRTUAL RANGE PROJECT.
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Creator
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Robledo, Luis, Sepulveda, Jose, University of Central Florida
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Abstract / Description
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After the accident of the STS 107 Columbia Space Shuttle, great concern has been focused on the risk associated to the population on the ground. Before this accident happened, re-entry routes as well as risk calculation of were not of public concern. Two issues that have been raised from this lamentable accident relate to spacecraft security and to public safety. The integration of a debris model has been part of the original conceptual architecture of the Virtual Range Project. Its...
Show moreAfter the accident of the STS 107 Columbia Space Shuttle, great concern has been focused on the risk associated to the population on the ground. Before this accident happened, re-entry routes as well as risk calculation of were not of public concern. Two issues that have been raised from this lamentable accident relate to spacecraft security and to public safety. The integration of a debris model has been part of the original conceptual architecture of the Virtual Range Project. Its integration has been considered as a specific research due to the complexity of the models and the difficulties to obtain them since the commercial off-the-shelf available software seems to be less accessible. This research provides solid information concerning what debris fragmentation models are, their fundamentals, their weaknesses and strengths. The research provides information of the main debris models being currently used by NASA which have direct relationship with the space programs conducted. This study also addresses the integration of a debris model into the Virtual Range Project. We created a provisional model based on the distribution of the Columbia debris fragments over Texas and part of Louisiana in order to create an analytical methodology as well. This analysis shows a way of integrating this debris model with a Geographic Information System as well as the integration of several raster and vector data sets which will provide the source data to compute the calculations. This research uses population data sets that allow the determination of the number of people at risk on the ground. The graphical and numerical analysis made can lead to the determination of new and more secure re-entry trajectories as well as further population-related security issues concerning this type of flights.
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Date Issued
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2004
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Identifier
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CFE0000193, ucf:46175
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0000193
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Title
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FINITE ELEMENT MODELING OF TIDES AND CURRENTS OF THE PASCAGOULA RIVER.
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Creator
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Wang, Qing, Hagen, Scott, University of Central Florida
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Abstract / Description
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This thesis focuses on the simulation of astronomic tides of the Pascagoula River. The work is comprised of five steps: 1) Production of a digital elevation model describing the entire Pascagoula River system; 2) Development of an inlet-based, unstructured mesh for inbank flow to better understand the basis of the hydrodynamics within the Pascagoula riverine system. In order to assist in the mesh development, a toolbox was constructed to implement one-dimensional river cross sections into the...
Show moreThis thesis focuses on the simulation of astronomic tides of the Pascagoula River. The work is comprised of five steps: 1) Production of a digital elevation model describing the entire Pascagoula River system; 2) Development of an inlet-based, unstructured mesh for inbank flow to better understand the basis of the hydrodynamics within the Pascagoula riverine system. In order to assist in the mesh development, a toolbox was constructed to implement one-dimensional river cross sections into the two-dimensional model; 3) Implementation of a sensitivity analysis of the Pascagoula River two inlet system to examine the inlet effects on tidal propagation; 4) Improvement of the inlet-based model by performing a preliminary assessment of a spatially varied bottom friction; 5) Implementation of an advection analysis to reveal its influence on the flow velocity and water elevation within the domain. The hydrodynamic model employed for calculating tides is ADCIRC-2DDI (ADvanced CIRCulation Model for Shelves, Coasts and Estuaries, Two-Dimensional Depth Integrated). This finite element based model solves the shallow water equations in their full nonlinear form. Boundary conditions including water surface elevation at the off-shore boundary and tidal potential terms allow the full simulation of astronomic tides. The improved astronomic tide model showed strong agreement with the historical data at seven water level monitoring gauge stations. The main conclusions of this research are: 1) The western inlet of the Pascagoula River is more dominant than the eastern inlet; however, it is necessary to include both inlets in the model. 2) Although advection plays a significant role in velocity simulation, water elevations are insensitive to advection. 3) The astronomic model is sensitive to bottom friction (both global and spatial variations); therefore, a spatially varied bottom friction coefficient is suggested. As a result of this successful effort to produce an astronomic tide model of the Pascagoula River, a comprehensive storm surge model can be developed. With the addition of inundation areas the surge model can be expected to accurately predict storm tides generated by hurricanes along the Gulf Coast.
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Date Issued
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2008
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Identifier
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CFE0002291, ucf:47840
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0002291
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Title
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THE EFFECTS OF AGE ON REPRODUCTION IN A CITRUS ROOT WEEVIL DIAPREPES ABBREVIATUS.
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Creator
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Chasez, Heather, Fedorka, Kenneth, University of Central Florida
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Abstract / Description
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Understanding the factors influencing mate choice is a major focus of sexual selection. Many factors are potentially involved, including age of the individual. The good genes model and the youth advantage model both make predictions about the effect of age on mate choice. Under the good genes model older mates would be the more preferable due to their proven high survivability. The ÃÂ"youth advantageÃÂ" model, predicts that young to intermediate age males...
Show moreUnderstanding the factors influencing mate choice is a major focus of sexual selection. Many factors are potentially involved, including age of the individual. The good genes model and the youth advantage model both make predictions about the effect of age on mate choice. Under the good genes model older mates would be the more preferable due to their proven high survivability. The ÃÂ"youth advantageÃÂ" model, predicts that young to intermediate age males would be more advantageous as mates because of a decrease in sperm quality and the possibility of increased germ-line mutations in older animals. I examined the effects of age on behavioral and physiological factors in Diaprepes abbreviatus experimentally. Both males and females were found to be the least optimal as mates during the intermediate stage of their lives, with preferences for young and old age classes. Females had higher fertilization rates when young and fertilization steadily declined with age, consistent with the youth advantage model. Males overall had higher fertilization rate and procured matings faster when they were older, which was in accordance with the good genes model, though experience could also play a role in this result. These data here suggest that in D. abbreviatus age may play an important role in mate choice decisions.
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Date Issued
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2011
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Identifier
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CFE0003568, ucf:48924
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0003568
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Title
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A Production and Cost Modeling Methodology of 2nd Generation Biofuel in the United States.
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Creator
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Poole, David, Kincaid, John, Mollaghasemi, Mansooreh, Geiger, Christopher, University of Central Florida
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Abstract / Description
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The use of biofuels in the United States has increased dramatically in the last few years. The largest source of feedstock for ethanol to date has been corn. However, corn is also a vitally important food crop and is used commonly as feed for cattle and other livestock. To prevent further diversion of an important food crop to production of ethanol, there is great interest in developing commercial-scale technologies to make ethanol from non-food crops, or other suitable plant material. This...
Show moreThe use of biofuels in the United States has increased dramatically in the last few years. The largest source of feedstock for ethanol to date has been corn. However, corn is also a vitally important food crop and is used commonly as feed for cattle and other livestock. To prevent further diversion of an important food crop to production of ethanol, there is great interest in developing commercial-scale technologies to make ethanol from non-food crops, or other suitable plant material. This is commonly referred to as biomass. A review is made of lignocellulosic sources being considered as feedstocks to produce ethanol. Current technologies for pretreatment and hydrolysis of the biomass material are examined and discussed. Production data and cost estimates are culled from the literature, and used to assist in development of mathematical models for evaluation of production ramp-up profiles, and cost estimation. These mathematical models are useful as a planning tool, and provide a methodology to estimate monthly production output and costs for labor, capital, operations and maintenance, feedstock, raw materials, and total cost. Existing credits for ethanol production are also considered and modeled. The production output in liters is modeled as a negative exponential growth curve, with a rate coefficient providing the ability to evaluate slower, or faster, growth in production output and its corresponding effect on monthly cost. The capital and labor costs per unit of product are determined by dividing the monthly debt service and labor costs by that month?s production value. The remaining cost components change at a constant rate in the simulation case studies. This methodology is used to calculate production levels and costs as a function of time for a 25 million gallon per year capacity cellulosic ethanol plant. The parameters of interest are calculated in MATLAB with a deterministic, continuous system simulation model. Simulation results for high, medium, and low cost case studies are included. Assumptions for the model and for each case study are included and some comparisons are made to cost estimates in the literature. While the cost per unit of product decreases and production output increases over time, some reasonable cost values are obtained by the end of the second year for both the low and medium cost case studies. By the end of Year 2, total costs for those case studies are $0.48 per liter and $0.88 per liter, respectively. These cost estimates are well within the reported range of values from the reviewed literature sources. Differing assumptions for calculations made by different sources make a direct cost comparison with the outputs of this modeling methodology extremely difficult. Proposals for reducing costs are introduced. Limitations and shortcomings of the research activity are discussed, along with recommendations for potential future work in improving the simulation model and model verification activities. In summary, the author was not able to find evidence?within the public domain?of any similar modeling and simulation methodology that uses a deterministic, continuous simulation model to evaluate production and costs as a function of time. This methodology is also unique in highlighting the important effect of production ramp-up on monthly costs for capital (debt service) and labor. The resultant simulation model can be used for planning purposes and provides an independent, unbiased estimate of cost as a function of time.
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Date Issued
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2012
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Identifier
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CFE0004424, ucf:49321
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0004424
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Title
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SOLAR AND FUEL CELL CIRCUIT MODELING, ANALYSIS AND INTEGRATIONS WITH POWER CONVERSION CIRCUITS FOR DISTRIBUTED GENERATION.
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Creator
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Krishnamurthy, Smitha, Yuan, Jiann, University of Central Florida
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Abstract / Description
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Renewable energy is considered to be one of the most promising alternatives for the growing energy demand in response to depletion of fossil fuels and undesired global warming issue. With such perspective, Solar Cells and Fuel Cells are most viable, environmentally sound, and sustainable energy sources for power generation. Solar and Fuel cells have created great interests in modern applications including distributed energy generation to provide clean energy. The purpose of this thesis was to...
Show moreRenewable energy is considered to be one of the most promising alternatives for the growing energy demand in response to depletion of fossil fuels and undesired global warming issue. With such perspective, Solar Cells and Fuel Cells are most viable, environmentally sound, and sustainable energy sources for power generation. Solar and Fuel cells have created great interests in modern applications including distributed energy generation to provide clean energy. The purpose of this thesis was to perform a detailed analysis and modeling of Solar and Fuel cells using Cadence SPICE, and to investigate dynamic interactions between the modules and power conversion circuits. Equivalent electronic static and dynamic models for Solar and Fuel Cells, their electrical characteristics, and typical power loss mechanisms associated with them are demonstrated with simulation results. Power conversion circuits for integration with the dynamic models of these renewable low voltage sources are specifically chosen to boost and regulate the input low dc voltage from the modules. The scope of this work was to analyze and model solar and fuel cells to study their terminal characteristics, power loss mechanisms, modules and their dynamics when interfaced with power converters, which would lead to better understanding of these renewable sources in power applications.
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Date Issued
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2009
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Identifier
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CFE0002815, ucf:48100
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0002815
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Title
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DISCOUNTING: AN EMPIRICAL JUSTIFICATION FOR ITS VALUE IN THE LODGING INDUSTRY.
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Creator
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Semrad, Kelly, Croes, Robertico, University of Central Florida
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Abstract / Description
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The central focus of this study is to provide an empirical explanation regarding the efficacy of the managerial expectation formation process as it contributes to the understanding of discounting room rates as a rational strategic phenomenon in the lodging industry. The study assesses the nature of the relationship between discounting hotel room rates and hotel financial performance when considering the non-stationary conditions of a time series data set. The study was rooted in an...
Show moreThe central focus of this study is to provide an empirical explanation regarding the efficacy of the managerial expectation formation process as it contributes to the understanding of discounting room rates as a rational strategic phenomenon in the lodging industry. The study assesses the nature of the relationship between discounting hotel room rates and hotel financial performance when considering the non-stationary conditions of a time series data set. The study was rooted in an operational based perspective with regard to the challenges presented by the perishable nature of room night sales - the loss of which may impact a managerÃÂ's fundamental responsibility: to generate maximum revenue from the existing hotel room capacity. Of critical importance to this study is whether the incremental use of discounting room rates could work to correct for temporal periods of decreased demand and thus increase short-term hotel financial performance. There is limited research regarding the empirical relationship between discounting room rates and hotel financial performance, as well as the internal process that a hotel manager uses to determine an accurate room rate that corresponds to seasonal lodging market demand conditions. An empirical foundation for this practice is lacking in the extant hospitality literature. Literature reveals that, although the lodging industry commonly incorporates discounting as a pricing strategy, recent research implies that high occupancy levels at discounted room rates do not necessarily lead to an increase in hotel financial performance. The contrast then between what is practiced and the recommendations from pricing strategy studies has led to lack of consistent agreement in current lodging literature regarding how discounting of hotel room rates relates to hotel financial performance. This study is at the forefront in its use of the methodological procedures that support a theoretical framework capable of providing explanations regarding managersÃÂ' internal process of discounting as an effective pricing strategy that could compensate for times of decreased room demand. An econometric case study research design was used in conjunction with a cointegration analysis and an error correction model (none of which are otherwise appropriated as assessment tools in the lodging industry). These applications provide a means to understand the expectation formation process of managersÃÂ' room price setting strategies. They also assess the empirical nature of the relationship between the variables by accounting for the erratic variations of room demand over time as induced by random error fluctuations. A non-deterministic system was assumed and supported through the analysis of the stationarity conditions of the time series data set under investigation. The distinguishing characteristics of a dynamic system that are recognized as traits of the lodging industry are further supported by the theoretical framework of the rational expectations theory and the cobweb model. The results of the study are based on secondary financial data sets that were provided by a midscale independently owned leisure hotel in the Orlando, FL market and that is located on Walt Disney World property. The results of this study delineate from the current normative economic recommendation based on descriptive research that claims discounting hotel room rates does not increase hotel financial performance. The current study does not draw an association between the variables from the presupposition of a deterministic marketplace, nor does it recommend to managers to hold a constant average daily rate over time. Based on the findings of the statistical procedures performed and the theoretical framework, the study contends that previous research may have incorrectly modeled room price expectations; elected to use inappropriate statistical tests; and, therefore, may have entertained misleading conclusions regarding the relationship between discounting of hotel room rates and hotel financial performance. Through use of an error correction model, the major findings of this study imply several concepts: that residuals may be treated as a variable within the studyÃÂ's model in order to better understand the short run dynamics that may lead to equilibrium correcting room price positions over the long run of time; that discounting room rates works in the short run; and, that managers use a rational price setting strategy to set future room rates. All of the aforementioned concepts fall within accordance of the rational expectations theory. The study concludes that while the constant room rate adjustments observed in the lodging industry may display what appears to be a random structure that deviates from the expected systematic, or stable, financial performance of a hotel over time, the deviations in performance are actually a rhythmic synthesized process of market information from past and current times. Hence, hotel managers appear to be using a backward looking model to forwardly project optimal room rates to match uncertain consumer demand. The empirical assessment employed in this study supports this determination.
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Date Issued
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2010
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Identifier
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CFE0003430, ucf:48411
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0003430
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Title
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MODELING MICROBIOLOGICAL AND CHEMICAL PROCESSES IN MUNICIPAL SOLID WASTE BIOREACTOR: DEVELOPMENT AND APPLICATIONS OF A THREE-PHASE NUMERICAL MODEL BIOKEMOD-3P.
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Creator
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Gawande, Nitin, Reinhart, Debra, University of Central Florida
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Abstract / Description
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The numerical computer models that simulate municipal solid waste (MSW) bioreactor landfills have mainly two components a biodegradation process module and a multi-phase flow module. The biodegradation model describes the chemical and microbiological processes of solid waste biodegradation. The models available to date include predefined solid waste biodegradation reactions and participating species. In a bioreactor landfill several processes, such as anaerobic and aerobic...
Show moreThe numerical computer models that simulate municipal solid waste (MSW) bioreactor landfills have mainly two components a biodegradation process module and a multi-phase flow module. The biodegradation model describes the chemical and microbiological processes of solid waste biodegradation. The models available to date include predefined solid waste biodegradation reactions and participating species. In a bioreactor landfill several processes, such as anaerobic and aerobic biodegradation, nitrogen and sulfate cycling, precipitation and dissolution of metals, and adsorption and gasification of various anthropogenic organic compounds, occur simultaneously. These processes may involve reactions of several species and the available biochemical models for solid waste biodegradation do not provide users with the flexibility to selectively simulate these processes. This research work includes the development of a generalized biochemical process model, BIOKEMOD-3P, which can accommodate a large number of species and process reactions. This model is able to simulate bioreactor landfill processes in a completely mixed condition; when coupled with a multi-phase model it will be able to simulate a full-scale bioreactor landfill. This generalized biochemical model can simulate laboratory and pilot-scale operations which are important to determine biochemical parameters important for simulation of full-scale operations. To illustrate application of BIOKEMOD-3P, two sets of laboratory MSW bioreactors were simulated in this research work. The first demonstrated simulation of data from anaerobic biodegradation of MSW in experimental bioreactors. In another application, simultaneous nitrification and denitrification processes in MSW bioreactors were simulated. The results from these simulations generated information about various modeling parameters that would help implement these processes in a full-scale bioreactor landfill operation.
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Date Issued
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2009
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Identifier
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CFE0002659, ucf:48227
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0002659
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Title
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A MATHEMATICAL STUDY OF MALARIA MODELS OF ROSS AND NGWA.
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Creator
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Plemmons, William, Rollins, David, University of Central Florida
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Abstract / Description
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Malaria is a vector borne disease that has been plaguing mankind since before recorded history. The disease is carried by three subspecies of mosquitoes Anopheles gambiae, Anopheles arabiensis and Anopheles funestu. These mosquitoes carry one of four type of Plasmodium specifically: P. falciparum, P. vivax, P. malariae or P. ovale. The disease is a killer; the World Health Organization (WHO) estimates that about 40% of the world's total populations live in areas where malaria is an...
Show moreMalaria is a vector borne disease that has been plaguing mankind since before recorded history. The disease is carried by three subspecies of mosquitoes Anopheles gambiae, Anopheles arabiensis and Anopheles funestu. These mosquitoes carry one of four type of Plasmodium specifically: P. falciparum, P. vivax, P. malariae or P. ovale. The disease is a killer; the World Health Organization (WHO) estimates that about 40% of the world's total populations live in areas where malaria is an endemic disease and as global warming occurs, endemic malaria will spread to more areas. The malaria parasite kills a child every 30 seconds. In Africa alone, as many as one million children die annually from malaria before they reach the age of 5. The World Health Organization has an estimate of 100-200 million victims annually. Malaria has many mathematical models and this paper will examine several different models in order to achieve a greater understanding of this disease.
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Date Issued
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2006
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Identifier
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CFE0001406, ucf:47070
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0001406
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Title
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PREDICTING ANXIETY FROM PARENT AND CHILDHOOD VARIABLES.
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Creator
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Fisak, Brian, Negy, Charles, University of Central Florida
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Abstract / Description
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The high prevalence rate, significant distress and impairment, and persistence of childhood anxiety disorders highlight the need for continued theoretical conceptualization and research into the developmental pathways associated these disorders. In response to this need, one goal this project was to examination and identify variables associated with the development and/or maintenance of child anxiety disorders. A second goal of this project was to examine the potential role of learning from...
Show moreThe high prevalence rate, significant distress and impairment, and persistence of childhood anxiety disorders highlight the need for continued theoretical conceptualization and research into the developmental pathways associated these disorders. In response to this need, one goal this project was to examination and identify variables associated with the development and/or maintenance of child anxiety disorders. A second goal of this project was to examine the potential role of learning from parents as a risk factor in the development of child anxiety, with a particular emphasis on three learning mechanisms: modeling, information transfer, and reinforcement of anxious behaviors. The third goal of this project was to compare and contrast the developmental predictors of anxiety in White versus Hispanic samples. Data was collected from a sample of mothers in the community with at least one child between the ages of 6 and 12, and an unrelated sample of young adults. Significant predictors of anxiety were identified in both samples, and the hypothesis that anxiety may, in part, be learned from parents was supported in both samples. In addition, results indicated different sets of predictors of anxiety in White versus Hispanic participants. Limitations and implications of the findings are discussed.
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Date Issued
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2006
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Identifier
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CFE0001261, ucf:46916
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0001261
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Title
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MODELING TRANSMISSION DYNAMICS OF TUBERCULOSIS INCLUDING VARIOUS LATENT PERIODS.
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Creator
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Atkins, Tracy, Mohapatra, Ram, University of Central Florida
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Abstract / Description
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The systems of equations created by Blower et al. (1995) and Jia et al. (2007) designed to model the dynamics of Tuberculosis are solved using the computer software SIMULINK. The results are first employed to examine the intrinsic transmission dynamics of the disease through two models developed by Blower et al. (1995). The "simple transmission model" was used primarily to give insight to the behavior of the susceptible, latent, and infectious groups of individuals. Then, we consider a more...
Show moreThe systems of equations created by Blower et al. (1995) and Jia et al. (2007) designed to model the dynamics of Tuberculosis are solved using the computer software SIMULINK. The results are first employed to examine the intrinsic transmission dynamics of the disease through two models developed by Blower et al. (1995). The "simple transmission model" was used primarily to give insight to the behavior of the susceptible, latent, and infectious groups of individuals. Then, we consider a more detailed transmission model which includes several additional factors. This model captures the dynamics of not only the susceptible, latent and infectious groups but also the non-infectious cases and the recovered cases. Using the SIMULINK results, it can be shown that the intrinsic dynamics of the disease contribute to the rise and decline of the disease seen in historical accounts. Next, the simulation results are used to study the equilibrium points of the disease which can be obtained by varying the parameters and therefore changing the value for the basic reproduction ratio (R0 ). Our model uses the system of equations developed by Jia et al. (2007). The SIMULINK results are used to visually confirm the hypothesis proposed by Jia et al. (2007) that the equilibrium behavior of the system when R0 > 1 is globally asymptotically stable.
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Date Issued
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2008
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Identifier
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CFE0002030, ucf:47606
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Format
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Document (PDF)
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PURL
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http://purl.flvc.org/ucf/fd/CFE0002030
Pages