Current Search: Linear (x)
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Title
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HIGH LINEARITY 5.8 GHZ POWER AMPLIFIER WITH AN INTERNAL LINEARIZER.
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Creator
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Wang, Yiheng, Yuan, Jiann S., University of Central Florida
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Abstract / Description
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A 5.8 GHz RF Power Amplifier (PA) is designed and fabricated in this work, which has very high linearity through a built-in linearizer. The PA is designed, post-layout simulated by Agilent Advanced Design System (ADS) software and fabricated by Win-Semiconductors 0.15µm pHEMT process technology. The post-layout simulation results illustrate the power amplifier can obtained an output power of 23.98 dBm, a power gain of 32.28 dB and a power added efficiency (PAE) of 29% at saturation region,...
Show moreA 5.8 GHz RF Power Amplifier (PA) is designed and fabricated in this work, which has very high linearity through a built-in linearizer. The PA is designed, post-layout simulated by Agilent Advanced Design System (ADS) software and fabricated by Win-Semiconductors 0.15µm pHEMT process technology. The post-layout simulation results illustrate the power amplifier can obtained an output power of 23.98 dBm, a power gain of 32.28 dB and a power added efficiency (PAE) of 29% at saturation region, the 3rd intermodulation distortion (IMD3) of -37.7 dBc at 0 dBm input power is attained when operation frequency is 5.8 GHz. We finally obtain that the output power of 17.97 dBm and power gain of 27.97 dB at input power of -10 dBm, PAE of 11.65% at input power of 0 dBm and the IMD3 of -25.66 dBc at -20 dBm input power by measurement, when operation frequency is 5.2 GHz. So the overall RF performance of the PA demonstrates high power, high efficiency and high linearity.
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Date Issued
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2011
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Identifier
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CFE0003615, ucf:48857
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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/CFE0003615
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Title
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Multi-level Optimization and Applications with Non-Traditional Game Theory.
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Creator
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Yun, Guanxiang, Zheng, Qipeng, Boginski, Vladimir, Karwowski, Waldemar, Yong, Jiongmin, University of Central Florida
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Abstract / Description
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We study multi-level optimization problem on energy system, transportation system and information network. We use the concept of boundedly rational user equilibrium (BRUE) to predict the behaviour of users in systems. By using multi-level optimization method with BRUE, we can help to operate the system work in a more efficient way. Based on the introducing of model with BRUE constraints, it will lead to the uncertainty to the optimization model. We generate the robust optimization as the...
Show moreWe study multi-level optimization problem on energy system, transportation system and information network. We use the concept of boundedly rational user equilibrium (BRUE) to predict the behaviour of users in systems. By using multi-level optimization method with BRUE, we can help to operate the system work in a more efficient way. Based on the introducing of model with BRUE constraints, it will lead to the uncertainty to the optimization model. We generate the robust optimization as the multi-level optimization model to consider for the pessimistic condition with uncertainty. This dissertation mainly includes four projects. Three of them use the pricing strategy as the first level optimization decision variable. In general, our models' first level's decision variables are the measures that we can control, but the second level's decision variables are users behaviours that can only be restricted within BRUE with uncertainty.
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Date Issued
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2019
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Identifier
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CFE0007881, ucf:52758
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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/CFE0007881
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Title
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THE LAST 2500 YEARS: DEFINING, DISSECTING AND DIRECTING THE LESS LINEAR MUSICAL.
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Creator
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Lewis, Andrew, Weaver, Earl, University of Central Florida
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Abstract / Description
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Since the first recorded theatrical events, theatre has been presented in a linear fashion. It is no surprise that the majority of American Musical Theatre also follows a linear plot conception. Musicals that blatantly defy linearity are often called ÃÂ"conceptÃÂ" musicals. However, there is a small portion of concept musicals that do not abandon their linear plot altogether, but instead choose to skew the line in order to give the audience a unique...
Show moreSince the first recorded theatrical events, theatre has been presented in a linear fashion. It is no surprise that the majority of American Musical Theatre also follows a linear plot conception. Musicals that blatantly defy linearity are often called ÃÂ"conceptÃÂ" musicals. However, there is a small portion of concept musicals that do not abandon their linear plot altogether, but instead choose to skew the line in order to give the audience a unique perspective of the story being told. This mass categorization does not accurately take into account the extreme difference in structure of the two types of concept musicals. For this purpose, I explored the notion of a new structural category, the Less Linear Concept Musical, in hopes of identifying the unique characteristics and challenges associated with this type of musical. Beginning with AristotleÃÂ's "The Poetics" and ending in modern day Musical Theatre, I examine key events in the shaping of this musical theatre form, as well as define the form itself. The application of this research culminated in a classroom presentation of Jason Robert BrownÃÂ's The Last Five Years, which I directed. I pose the question, ÃÂ"Can sound direction conquer the pitfalls found within the Less Linear Concept Musical?ÃÂ"
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Date Issued
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2010
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Identifier
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CFE0003361, ucf:48479
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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/CFE0003361
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Title
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Comparison of Second Order Conformal Symplectic Schemes with Linear Stability Analysis.
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Creator
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Floyd, Dwayne, Moore, Brian, Schober, Constance, Mohapatra, Ram, University of Central Florida
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Abstract / Description
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Numerical methods for solving linearly damped Hamiltonian ordinary differential equations are analyzed and compared. The methods are constructed from the well-known St(&)#246;rmer-Verlet and implicit midpoint methods. The structure preservation properties of each method are shown analytically and numerically. Each method is shown to preserve a symplectic form up to a constantand are therefore conformal symplectic integrators, with each method shown to accurately preserve the rate of momentum...
Show moreNumerical methods for solving linearly damped Hamiltonian ordinary differential equations are analyzed and compared. The methods are constructed from the well-known St(&)#246;rmer-Verlet and implicit midpoint methods. The structure preservation properties of each method are shown analytically and numerically. Each method is shown to preserve a symplectic form up to a constantand are therefore conformal symplectic integrators, with each method shown to accurately preserve the rate of momentum dissipation. An analytical linear stability analysis is completed for each method, establishing thresholds between the value of the damping coefficient and the step-size that ensure stability. The methods are all second order and the preservation of the rate of energy dissipation is compared to that of a third order Runge-Kutta method that does not preserve conformal properties. Numerical experiments will include the damped harmonic oscillator and the damped nonlinear pendulum.
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Date Issued
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2014
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Identifier
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CFE0005793, ucf:50051
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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/CFE0005793
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Title
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Thermoacoustic Reimann Solver Finite Volume Method with Application to Turbulent Premixed Gas Turbine Combustion Instability.
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Creator
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Johnson, Perry, Kapat, Jayanta, Ilie, Marcel, Vasu Sumathi, Subith, Shivamoggi, Bhimsen, University of Central Florida
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Abstract / Description
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This thesis describes the development, verification, and validation of a three dimensional time domain thermoacoustic solver. The purpose of the solver is to predict the frequencies, modeshapes, linear growth rates, and limit cycle amplitudes for combustion instability modes in gas turbine combustion chambers. The linearized Euler equations with nonlinear heat release source terms are solved using the finite volume method. The treatment of mean density gradients was found to be vital to the...
Show moreThis thesis describes the development, verification, and validation of a three dimensional time domain thermoacoustic solver. The purpose of the solver is to predict the frequencies, modeshapes, linear growth rates, and limit cycle amplitudes for combustion instability modes in gas turbine combustion chambers. The linearized Euler equations with nonlinear heat release source terms are solved using the finite volume method. The treatment of mean density gradients was found to be vital to the success of frequency and modeshape predictions due to the sharp density gradients that occur across deflagration waves. In order to treat mean density gradients with physical fidelity, a non-conservative finite volume method based on the wave propagation approach to the Riemann problem is applied. For modelling unsteady heat release, user input flexibility is maximized using a virtual class hierarchy within the OpenFOAM C++ library. Unsteady heat release based on time lag models are demonstrated. The solver gives accurate solutions compared with analytical methods for one-dimensional cases involving mean density gradients, cross-sectional area changes, uniform mean flow, arbitrary impedance boundary conditions, and unsteady heat release in a one-dimensional Rijke tube. The solver predicted resonant frequencies within 1% of the analytical solution for these verification cases, with the dominant component of the error coming from the finite time interval over which the simulation is performed. The linear growth rates predicted by the solver for the Rijke tube verification were within 5% of the theoretical values, provided that numerical dissipation effects were controlled. Finally, the solver is then used to predict the frequencies and limit cycle amplitudes for two lab scale experiments in which detailed acoustics data are available for comparison. For experiments at the University of Melbourne, an empirical flame describing function was provided. The present simulation code predicted a limit cycle of 0.21 times the mean pressure, which was in close agreement with the estimate of 0.25 from the experimental data. The experiments at Purdue University do not yet have an empirical flame model, so a general vortex-shedding model is proposed on physical grounds. It is shown that the coefficients of the model can be tuned to match the limit cycle amplitude of the 2L mode from the experiment with the same accuracy as the Melbourne case. The code did not predict the excitation of the 4L mode, therefore it is concluded that the vortex-shedding model is not sufficient and must be supplemented with additional heat release models to capture the entirety of the physics for this experiment.
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Date Issued
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2013
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Identifier
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CFE0005098, ucf:50730
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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/CFE0005098
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Title
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PHASE-SHIFTING HAAR WAVELETS FOR IMAGE-BASED RENDERING APPLICATIONS.
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Creator
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Alnasser, Mais, Foroosh, Hassan, University of Central Florida
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Abstract / Description
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In this thesis, we establish the underlying research background necessary for tackling the problem of phase-shifting in the wavelet transform domain. Solving this problem is the key to reducing the redundancy and huge storage requirement in Image-Based Rendering (IBR) applications, which utilize wavelets. Image-based methods for rendering of dynamic glossy objects do not truly scale to all possible frequencies and high sampling rates without trading storage, glossiness, or computational time,...
Show moreIn this thesis, we establish the underlying research background necessary for tackling the problem of phase-shifting in the wavelet transform domain. Solving this problem is the key to reducing the redundancy and huge storage requirement in Image-Based Rendering (IBR) applications, which utilize wavelets. Image-based methods for rendering of dynamic glossy objects do not truly scale to all possible frequencies and high sampling rates without trading storage, glossiness, or computational time, while varying both lighting and viewpoint. This is due to the fact that current approaches are limited to precomputed radiance transfer (PRT), which is prohibitively expensive in terms of memory requirements when both lighting and viewpoint variation are required together with high sampling rates for high frequency lighting of glossy material. At the root of the above problem is the lack of a closed-form run-time solution to the nontrivial problem of rotating wavelets, which we solve in this thesis. We specifically target Haar wavelets, which provide the most efficient solution to solving the tripleproduct integral, which in turn is fundamental to solving the environment lighting problem. The problem is divided into three main steps, each of which provides several key theoretical contributions. First, we derive closed-form expressions for linear phase-shifting in the Haar domain for one-dimensional signals, which can be generalized to N-dimensional signals due to separability. Second, we derive closed-form expressions for linear phase-shifting for two-dimensional signals that are projected using the non-separable Haar transform. For both cases, we show that the coefficients of the shifted data can be computed solely by using the coefficients of the original data. We also derive closed-form expressions for non-integer shifts, which has not been reported before. As an application example of these results, we apply the new formulae to image shifting, rotation and interpolation, and demonstrate the superiority of the proposed solutions to existing methods. In the third step, we establish a solution for non-linear phase-shifting of two-dimensional non-separable Haar-transformed signals, which is directly applicable to the original problem of image-based rendering. Our solution is the first attempt to provide an analytic solution to the difficult problem of rotating wavelets in the transform domain.
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Date Issued
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2008
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Identifier
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CFE0002214, ucf:47882
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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/CFE0002214
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Title
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PREVALENCE OF DENTAL PATHOLOGY IN A JUVENILE POPULATION FROM THE ANCIENT MAYA SITE OF ALTUN HA.
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Creator
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Lefebvre, Lindsey D., Schultz, John, University of Central Florida
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Abstract / Description
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The present research seeks to assesses the presence and prevalence of two distinct dental pathologies: linear enamel hypoplasia and caries in an ancient Maya juvenile subsample from Altun Ha, Belize spanning the Preclassic (ca. 600 B.C.) through the Terminal Classic (ca. 900 A.D.) periods. Teeth offer a remarkable wealth of information about the human experience in the past. Developmental and post-eruption pathology can provide insight into cultural and evolutionary processes by illuminating...
Show moreThe present research seeks to assesses the presence and prevalence of two distinct dental pathologies: linear enamel hypoplasia and caries in an ancient Maya juvenile subsample from Altun Ha, Belize spanning the Preclassic (ca. 600 B.C.) through the Terminal Classic (ca. 900 A.D.) periods. Teeth offer a remarkable wealth of information about the human experience in the past. Developmental and post-eruption pathology can provide insight into cultural and evolutionary processes by illuminating social and biological factors such as diet, weaning, illness, and overall health that manifest in observable changes to the composition of teeth. In addition, growth and developmental stages of juveniles provide an ideal framework in which to qualify paleopathological research. From a biological standpoint, high ante-mortem resistance to physiological stress and post-mortem preservation make teeth ideal for analyses of pathology in archaeological contexts. For the analysis of the Altun Ha juvenile subsample, a cohort approach is used in the presentation and discussion of results. Discrete pathologies are analyzed based on age cohorts, individual, tooth type, tooth surface location, and archaeological time period. The results indicate an increase in prevalence of pathology concurrent with increasing dental age as well as a predisposition to pathology among specific tooth types and locations on the crown surface and within the dental arcade as well as temporal shifts in pathology prevalence. These analyses demonstrate the importance of assessing juveniles within the archaeological record with emphasis on the transitory developmental stages experienced by children.
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Date Issued
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2017
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Identifier
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CFH2000383, ucf:45882
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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/CFH2000383
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Title
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APPLYING LOG-LINEAR MODELS AND GIS TO STUDY THE SAFETY OF PEDESTRIANS AND BICYCLISTS : A CASE STUDY OF ORANGE COUNTY SCHOOL CHILDREN.
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Creator
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Chundi, Sai Srinivas, Mohamed, Abdel Aty, University of Central Florida
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Abstract / Description
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Abstract Pedestrian /bicycle safety of school children has been a growing menace that has been attracting attention from transportation professionals, school boards, media and the community all over the country. As such there has been a necessity to identify critical variables and assess their importance in pedestrian/bicycle crashes occurring in and around school zones. The current study is an endeavor in this direction. The literature review identified some studies that were conducted on...
Show moreAbstract Pedestrian /bicycle safety of school children has been a growing menace that has been attracting attention from transportation professionals, school boards, media and the community all over the country. As such there has been a necessity to identify critical variables and assess their importance in pedestrian/bicycle crashes occurring in and around school zones. The current study is an endeavor in this direction. The literature review identified some studies that were conducted on school zone safety related to pedestrian/bicyclist crashes. Most of the studies pertained to crashes with all age groups. There have been few studies with emphasis only on school aged children. In this study we focus on pedestrian age group (4 to 18 years), the time of the day when the school children are expected to be commuting (6:30 AM to 10:00 AM and 1:00 PM to 5:00.PM), the day of week (Monday through Friday) and the days when the school is opened (January 6th to May 31st and August 6th to December 21st). Geographical Information Systems was used to locate buffer zones around schools with higher crash incidence rates. The use of log-linear analysis has culminated in explaining the relationship between various variables and crash incidence or crash frequency Crash data for this study was obtained in the form of crash database and GIS maps from the Department of Highway Safety and Motor Vehicles and the Orange County School Board respectively. Crash reports were downloaded from the CAR database of the FDOT mainframe website. The crash data was related to the GIS maps to visually depict the proximity of crashes to the school zones and thus identified risky schools and school districts. It was concluded from the spatial analysis that the incidence of crashes was higher at middle schools. In the log-linear analysis different models were i tested to explain the effects of driver characteristics, geometric characteristics and pedestrian characteristics on the crash frequency. It was found that driver age, number of lanes, median type, pedestrian age and speed limit are the critical variables in explaining crash frequency. By examining the levels of the variables that were significantly involved in the crashes we would get an insight on ways to explain and control pedestrian/bicyclists crashes at school zones. It is hoped that this thesis would make an active contribution in improving the safety of bicyclists and pedestrians in and around school zones and make the schools much safer for the children.
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Date Issued
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2005
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Identifier
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CFE0000885, ucf:46643
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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/CFE0000885
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Title
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VECTORPAD: A TOOL FOR VISUALIZING VECTOR OPERATIONS.
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Creator
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Bott, Jared, LaViola, Joseph, University of Central Florida
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Abstract / Description
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Visualization of three-dimensional vector operations can be very helpful in understanding vector mathematics. However, creating these visualizations using traditional WIMP interfaces can be a troublesome exercise. In this thesis, we present VectorPad, a pen-based application for three-dimensional vector mathematics visualization. VectorPad allows users to define vectors and perform mathematical operations upon them through the recognition of handwritten mathematics. The VectorPad user...
Show moreVisualization of three-dimensional vector operations can be very helpful in understanding vector mathematics. However, creating these visualizations using traditional WIMP interfaces can be a troublesome exercise. In this thesis, we present VectorPad, a pen-based application for three-dimensional vector mathematics visualization. VectorPad allows users to define vectors and perform mathematical operations upon them through the recognition of handwritten mathematics. The VectorPad user interface consists of a sketching area, where the user can write vector definitions and other mathematics, and a 3D graph for visualization. After recognition, vectors are visualized dynamically on the graph, which can be manipulated by the user. A variety of mathematical operations can be performed, such as addition, subtraction, scalar multiplication, and cross product. Animations show how operations work on the vectors. We also performed a short, informal user study evaluating the user interface and visualizations of VectorPad. VectorPad's visualizations were generally well liked; results from the study show a need to provide a more comprehensive set of visualization tools as well as refinement to some of the animations.
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Date Issued
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2009
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Identifier
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CFE0002827, ucf:48087
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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/CFE0002827
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Title
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LINEAR ENAMEL HYPOPLASIA AT SANTA RITA COROZAL, BELIZE.
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Creator
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Tetlow, Andrew, Chase, Arlen, University of Central Florida
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Abstract / Description
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The focus of this thesis is an analysis of a sample of dentition collected from the Postclassic Maya site of Santa Rita Corozal in Northern Belize. The goal of this study is to determine what the presence (or absence) of Linear Enamel Hypoplasia (LEH) can demonstrate about the general health (i.e. stress, disease, nutrition, and weaning age) and social status of a single subset of the Late Postclassic (900-1500 CE) Maya living at Santa Rita Corozal. Specifically, this thesis focuses on...
Show moreThe focus of this thesis is an analysis of a sample of dentition collected from the Postclassic Maya site of Santa Rita Corozal in Northern Belize. The goal of this study is to determine what the presence (or absence) of Linear Enamel Hypoplasia (LEH) can demonstrate about the general health (i.e. stress, disease, nutrition, and weaning age) and social status of a single subset of the Late Postclassic (900-1500 CE) Maya living at Santa Rita Corozal. Specifically, this thesis focuses on dentition of thirteen individuals from a large Postclassic platform group. The sample consists of sub-adult and adult female dentition from individuals that are associated with the same relative time period (Late Postclassic). The question being addressed in this thesis is: why has LEH presented in these individuals? These samples will also be compared to other studies involving LEH throughout the Maya area, in both similar and dissimilar environments. The preponderance of female and sub-adult remains also makes this platform group a very interesting topic of study for LEH in the Maya area, as it is unusual to find a concentrated area of individuals such as these. Importantly, the results of this study show that there is no significant relationship between general levels of stress and the overall status of an individual. Measurements collected from the LEH affected teeth demonstrate that all of the LEH episodes occurred before the age of 6. The mean age for the teeth sampled that show signs of LEH is 3.5 years, which is consistent with theories pertaining to the weaning age of the Maya during concomitant time periods. However, the size of this sample precludes any concrete conclusions about weaning ages and stress in general among the Maya at Santa Rita Corozal. It is also possible that these events are related to larger issues such as regional droughts or water-born disease.
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Date Issued
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2010
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Identifier
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CFE0003481, ucf:48968
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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/CFE0003481
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Title
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EMERGENCY EVACUATION ROUTE PLANNING CONSIDERING HUMAN BEHAVIOR DURING SHORT- AND NO-NOTICE EMERGENCY SITUATIONS.
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Creator
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Kittirattanapaiboon, Suebpong, Geiger, Christopher, University of Central Florida
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Abstract / Description
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Throughout United States and world history, disasters have caused not only significant loss of life, property but also enormous financial loss. The tsunami that occurred on December 26, 2004 is a telling example of the devastation that can occur unexpectedly. This unexpected natural event never happened before in this area. In addition, there was a lack of an emergency response plan for events of that magnitude. Therefore, this event resulted not only in a natural catastrophe for the people...
Show moreThroughout United States and world history, disasters have caused not only significant loss of life, property but also enormous financial loss. The tsunami that occurred on December 26, 2004 is a telling example of the devastation that can occur unexpectedly. This unexpected natural event never happened before in this area. In addition, there was a lack of an emergency response plan for events of that magnitude. Therefore, this event resulted not only in a natural catastrophe for the people of South and Southeast Asia, but it is also considered one of the greatest natural disasters in world history. After the giant wave dissipated, there were more than 230,000 people dead and more than US$10 billion in property damage and loss. Another significant event was the terrorist incident on September 11, 2001 (commonly referred to as 9/11) in United States. This event was unexpected and an unnatural, i.e., man-made event. It resulted in approximately 3,000 lives lost and about US$21 billion in property damage. These and other unexpected (or unanticipated) events give emergency management officials short- or no-notice to prevent or respond to the situation. These and other facts motivate the need for better emergency evacuation route planning (EERP) approaches in order to minimize the loss of human lives and property in short- or no-notice emergency situations. This research considers aspects of evacuation routing that have received little attention in research and, more importantly, in practice. Previous EERP models only either consider unidirectional evacuee flow from the source of a hazard to destinations of safety or unidirectional emergency first responder flow to the hazard source. However, in real-life emergency situations, these heterogeneous, incompatible flows occur simultaneously over a bi-directional capacitated lane-based travel network, especially in short- and no-notice emergencies. After presenting a review of the work related to the multiple flow EERP problem, mathematical formulations are presented for the EERP problem where the objective for each problem is to identify an evacuation routing plan (i.e., a traffic flow schedule) that maximizes evacuee and responder flow and minimizes network clearance time of both types of flow. In addition, we integrate the general human response behavior flow pattern, where the cumulative flow behavior follows different degrees of an S-shaped curve depending upon the level of the evacuation order. We extend the analysis to consider potential traffic flow conflicts between the two types of flow under these conditions. A conflict occurs when flow of different types occupy a roadway segment at the same time. Further, with different degrees of flow movement flow for both evacuee and responder flow, the identification of points of flow congestion on the roadway segments that occur within the transportation network is investigated.
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Date Issued
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2009
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Identifier
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CFE0002645, ucf:48229
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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/CFE0002645
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Title
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Investigating the Predictive Power of Student Characteristics on Success in Studio-mode, Algebra-based Introductory Physics Courses.
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Creator
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Pond, Jarrad, Rahman, Talat, Chini, Jacquelyn, Mucciolo, Eduardo, Butler, Malcolm, University of Central Florida
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Abstract / Description
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As part of a project to explore the differential success of similar implementations of the studio-mode of physics instruction, the objective of this work is to investigate the characteristics of students enrolled in algebra-based, studio-mode introductory physics courses at various universities in order to evaluate what effects these characteristics have on different measures of student success, such as gains in conceptual knowledge, shifts to more favorable attitudes toward physics, and...
Show moreAs part of a project to explore the differential success of similar implementations of the studio-mode of physics instruction, the objective of this work is to investigate the characteristics of students enrolled in algebra-based, studio-mode introductory physics courses at various universities in order to evaluate what effects these characteristics have on different measures of student success, such as gains in conceptual knowledge, shifts to more favorable attitudes toward physics, and final course grades. In my analysis, I explore the strategic self-regulatory, motivational, and demographic characteristics of students in algebra-based, studio-mode physics courses at three universities: the University of Central Florida (UCF), Georgia State University (GSU), and George Washington University (GW). Each of these institutions possesses varying student populations and differing levels of success in their studio-mode physics courses, as measured by students' overall average conceptual learning gains. In order to collect information about the students at each institution, I compiled questions from several existing questionnaires designed to measure student characteristics such as study strategies and motivations for learning physics, and organization of scientific knowledge. I also gathered student demographic information. This compiled survey, named the Student Characteristics Survey (SCS) was given at all three institutions. Using similar information collected from students, other studies (J. A. Chen, 2012; Nelson, Shell, Husman, Fishman, (&) Soh, 2015; Schwinger, Steinmayr, (&) Spinath, 2012; Shell (&) Husman, 2008; Shell (&) Soh, 2013; Tuominen-Soini, Salmela-Aro, (&) Niemivirta, 2011; Vansteenkiste, Soenens, Sierens, Luyckx, (&) Lens, 2009) have identified distinct learning profiles across varying student populations. Using a person-centered approach, I used model-based cluster analysis methods (Gan, Ma, (&) Wu, 2007) to organize students into distinct groups. From this analysis, I identified five distinct learning profiles in the population of physics students, similar to those found in previous research. In addition, student outcome information was gathered from both UCF and GSU. Conceptual inventory responses were gathered at both institutions, and attitudinal survey results and course grades were gathered at UCF. No student outcome data was gathered at GW; thus, GW is represented in analyses involving information compiled solely from the SCS, but GW is not represented in analyses involving student outcome information. Then, I use Automatic Linear Modeling, an application of multiple linear regression modeling (IBM, 2012, 2013), to identify which demographic variables (including the identified learning profiles) are the most influential in predicting student outcomes, such as scores on the Force Concept Inventory (FCI), the Conceptual Survey of Electricity and Magnetism (CSEM), and the Colorado Learning Attitudes about Sciences Survey (CLASS), both pre- and post-instruction. Modeling is conducted on the entire available dataset as a whole and is also conducted with the data disaggregated by institution in order to identify any differential effects that student characteristics may have at predicting student success at the different institutions. In addition, instructors teaching algebra-based, studio-mode introductory physics courses are interviewed about what makes students successful in order to better understand what instructors perceive is important for students to excel in their physics courses. Furthermore, student survey takers were interviewed to help verify their study strategies and motivations as measured by the SCS.The above analysis provides evidence that, on average, gaps in student understanding exist based on several demographic characteristics, such a gender, ethnicity, high school physics experience, and SAT Math score, and these results are generally consistent with those found in the literature. Disaggregation by institution reveals that differential effects from demographic variables exist; thus, similar groups of students at separate institutions attain different student outcomes. Overall, this is an undesirable observation, as the physics education research community strives to reduce such inequity in physics classrooms; however, identification of specific inequities and gaps in learning will help to inform further research investigations. Research should continue in the form of in-depth investigations into how individual instructors teach algebra-based studio-mode introductory physics courses, focusing on instructors' approaches to the studio-mode of instruction and uses of active learning techniques. Also, investigation of instructor awareness of demographic-driven gaps in student understanding would give insight into if and how instructors may be attempting to better understand the needs of different students. In addition, where a wide range of demographic data are available, I encourage institutions to conduct similar analyses as those presented here in order to identify any gaps in student understanding and place them in their institutional contexts for comparisons to other universities. Furthermore, as a result of my work, I find the identified learning profiles to have a significant association with students' attitudes toward physics, as measured by the CLASS questionnaire, both pre- and post-instruction. This relationship between learning profile and CLASS Pre-score is one that can help give instructors practical insight into students' study strategies and motivations at the very beginning of the physics course. By possessing knowledge of which students do and do not possess adaptive learning strategies early on, instructors can better optimize initial student groups by considering results of student outcome measures, adjust lesson plans, and assess students' needs accordingly.
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Date Issued
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2016
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Identifier
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CFE0006376, ucf:51515
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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/CFE0006376
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Title
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CONAE MicroWave Radiometer (MWR) Counts to Brightness Temperature Algorithm.
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Creator
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Ghazi, Zoubair, Jones, W Linwood, Wei, Lei, Mikhael, Wasfy, Wu, Thomas, Junek, William, Piepmeier, Jeffrey, University of Central Florida
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Abstract / Description
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This dissertation concerns the development of the MicroWave Radiometer (MWR) brightness temperature (Tb) algorithm and the associated algorithm validation using on-orbit MWR Tb measurements. This research is sponsored by the NASA Earth Sciences Aquarius Mission, a joint international science mission, between NASA and the Argentine Space Agency (Comision Nacional de Actividades Espaciales, CONAE). The MWR is a CONAE developed passive microwave instrument operating at 23.8 GHz (K-band) H-pol...
Show moreThis dissertation concerns the development of the MicroWave Radiometer (MWR) brightness temperature (Tb) algorithm and the associated algorithm validation using on-orbit MWR Tb measurements. This research is sponsored by the NASA Earth Sciences Aquarius Mission, a joint international science mission, between NASA and the Argentine Space Agency (Comision Nacional de Actividades Espaciales, CONAE). The MWR is a CONAE developed passive microwave instrument operating at 23.8 GHz (K-band) H-pol and 36.5 GHz (Ka-band) H- (&) V-pol designed to complement the Aquarius L-band radiometer/scatterometer, which is the prime sensor for measuring sea surface salinity (SSS). MWR measures the Earth's brightness temperature and retrieves simultaneous, spatially collocated, environmental measurements (surface wind speed, rain rate, water vapor, and sea ice concentration) to assist in the measurement of SSS.This dissertation research addressed several areas including development of: 1) a signal processing procedure for determining and correcting radiometer system non-linearity; 2) an empirical method to retrieve switch matrix loss coefficients during thermal-vacuum (T/V) radiometric calibration test; and 3) an antenna pattern correction (APC) algorithm using Inter-satellite radiometric cross-calibration of MWR with the WindSat satellite radiometer. The validation of the MWR counts-to-Tb algorithm was performed using two years of on-orbit data, which included special deep space calibration measurements and routine clear sky ocean/land measurements.
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Date Issued
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2014
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Identifier
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CFE0005496, ucf:50366
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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/CFE0005496
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Title
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General Vector Explicit - Impact Time and Angle Control Guidance.
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Creator
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Robinson, Loren, Qu, Zhihua, Behal, Aman, Xu, Yunjun, University of Central Florida
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Abstract / Description
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This thesis proposes and evaluates a new cooperative guidance law called General Vector Explicit -Impact Time and Angle Control Guidance (GENEX-ITACG). The motivation for GENEX-ITACGcame from an explicit trajectory shaping guidance law called General Vector Explicit Guidance(GENEX). GENEX simultaneously achieves design specifications on miss distance and terminalmissile approach angle while also providing a design parameter that adjusts the aggressiveness ofthis approach angle. Encouraged by...
Show moreThis thesis proposes and evaluates a new cooperative guidance law called General Vector Explicit -Impact Time and Angle Control Guidance (GENEX-ITACG). The motivation for GENEX-ITACGcame from an explicit trajectory shaping guidance law called General Vector Explicit Guidance(GENEX). GENEX simultaneously achieves design specifications on miss distance and terminalmissile approach angle while also providing a design parameter that adjusts the aggressiveness ofthis approach angle. Encouraged by the applicability of this user parameter, GENEX-ITACG is anextension that allows a salvo of missiles to cooperatively achieve the same objectives of GENEXagainst a stationary target through the incorporation of a cooperative trajectory shaping guidancelaw called Impact Time and Angle Control Guidance (ITACG).ITACG allows a salvo of missile to simultaneously hit a stationary target at a prescribed impactangle and impact time. This predetermined impact time is what allows each missile involvedin the salvo attack to simultaneously arrived at the target with unique approach angles, whichgreatly increases the probability of success against well defended targets. GENEX-ITACG furtherincreases this probability of kill by allowing each missile to approach the target with a uniqueapproach angle rate through the use of a user design parameter.The incorporation of ITACG into GENEX is accomplished through the use of linear optimal controlby casting the cost function of GENEX into the formulation of ITACG. The feasibility GENEXITACGis demonstrated across three scenarios that demonstrate the ITACG portion of the guidancelaw, the GENEX portion of the guidance law, and finally the entirety of the guidance law. Theresults indicate that GENEX-ITACG is able to successfully guide a salvo of missiles to simultaneouslyhit a stationary target at a predefined terminal impact angle and impact time, while alsoallowing the user to adjust the aggressiveness of approach.
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Date Issued
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2015
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Identifier
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CFE0005876, ucf:50868
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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/CFE0005876
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Title
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HOPF BIFURCATION ANALYSIS OF CHAOTIC CHEMICAL REACTOR MODEL.
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Creator
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Mandragona, Daniel, Choudhury, Roy, University of Central Florida
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Abstract / Description
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Bifurcations in Huang's chaotic chemical reactor system leading from simple dynamics into chaotic regimes are considered. Following the linear stability analysis, the periodic orbit resulting from a Hopf bifurcation of any of the six fixed points is constructed analytically by the method of multiple scales across successively slower time scales, and its stability is then determined by the resulting final secularity condition. Furthermore, we run numerical simulations of our chemical reactor...
Show moreBifurcations in Huang's chaotic chemical reactor system leading from simple dynamics into chaotic regimes are considered. Following the linear stability analysis, the periodic orbit resulting from a Hopf bifurcation of any of the six fixed points is constructed analytically by the method of multiple scales across successively slower time scales, and its stability is then determined by the resulting final secularity condition. Furthermore, we run numerical simulations of our chemical reactor at a particular fixed point of interest, alongside a set of parameter values that forces our system to undergo Hopf bifurcation. These numerical simulations then verify our analysis of the normal form.
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Date Issued
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2018
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Identifier
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CFH2000342, ucf:45831
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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/CFH2000342
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Title
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PARAMETER ESTIMATION IN LINEAR REGRESSION.
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Creator
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Ollikainen, Kati, Malone, Linda, University of Central Florida
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Abstract / Description
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Today increasing amounts of data are available for analysis purposes and often times for resource allocation. One method for analysis is linear regression which utilizes the least squares estimation technique to estimate a model's parameters. This research investigated, from a user's perspective, the ability of linear regression to estimate the parameters' confidence intervals at the usual 95% level for medium sized data sets. A controlled environment using simulation with known...
Show moreToday increasing amounts of data are available for analysis purposes and often times for resource allocation. One method for analysis is linear regression which utilizes the least squares estimation technique to estimate a model's parameters. This research investigated, from a user's perspective, the ability of linear regression to estimate the parameters' confidence intervals at the usual 95% level for medium sized data sets. A controlled environment using simulation with known data characteristics (clean data, bias and or multicollinearity present) was used to show underlying problems exist with confidence intervals not including the true parameter (even though the variable was selected). The Elder/Pregibon rule was used for variable selection. A comparison of the bootstrap Percentile and BCa confidence interval was made as well as an investigation of adjustments to the usual 95% confidence intervals based on the Bonferroni and Scheffe multiple comparison principles. The results show that linear regression has problems in capturing the true parameters in the confidence intervals for the sample sizes considered, the bootstrap intervals perform no better than linear regression, and the Scheffe method is too wide for any application considered. The Bonferroni adjustment is recommended for larger sample sizes and when the t-value for a selected variable is about 3.35 or higher. For smaller sample sizes all methods show problems with type II errors resulting from confidence intervals being too wide.
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Date Issued
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2006
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Identifier
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CFE0001482, ucf:47081
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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/CFE0001482
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Title
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THE APPLICATION OF "CRASHING" A PROJECT NETWORK TO SOLVE THE TIME/COST TRADEOFF IN RECAPITALIZATION OF THE UH-60A HELICOPTER.
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Creator
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Fortier, Gregory, Reilly, Charles, University of Central Florida
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Abstract / Description
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Since the beginning of project management, people have been asked to perform "more with less" in expeditious time while attempting to balance the inevitable challenge of the time/cost tradeoff. This is especially true within the Department of Defense today in prosecuting the Global War on Terrorism both in Afghanistan and Iraq. An unprecedented and consistent level of Operational Tempo has generated heavy demands on current equipment and has subsequently forced the need to recapitalize...
Show moreSince the beginning of project management, people have been asked to perform "more with less" in expeditious time while attempting to balance the inevitable challenge of the time/cost tradeoff. This is especially true within the Department of Defense today in prosecuting the Global War on Terrorism both in Afghanistan and Iraq. An unprecedented and consistent level of Operational Tempo has generated heavy demands on current equipment and has subsequently forced the need to recapitalize several legacy systems until suitable replacements can be implemented. This paper targets the UH-60A:A Recapitalization Program based at the Corpus Christi Army Depot in Corpus Christi, Texas. More specifically, we examine one of the nine existing project sub-networks within the UH-60A:A program, the structural/electrical upgrade phase. In crashing (i.e. adding manpower or labor hours) the network, we determine the minimal cost required to reduce the total completion time of the 68 activities within the network before a target completion time. A linear programming model is formulated and then solved for alternative scenarios. The first scenario is prescribed by the program manager and consists of simply hiring additional contractors to augment the existing personnel. The second and third scenarios consist of examining the effects of overtime, both in an aggressive situation (with limited longevity) and a more moderate situation (displaying greater sustainability over time). The initial linear programming model (Scenario 1) is crashed using estimates given from the program scheduler. The overtime models are crashed using reduced-time crash estimates. For Scenarios 2 and 3, the crashable times themselves are reduced by 50% and 75%, respectively. Initial results indicate that a completion time of 79.5 days is possible without crashing any activities in the network. The five-year historical average completion time is 156 days for this network. We continue to crash the network in each of the three scenarios and determine that the absolute shortest feasible completion times, 73 days for Scenario 1, 76 days for Scenario 2, and 77.5 days for Scenario 3. We further examine the models to observe similarities and differences in which activities get targeted for crashing and how that reduction affects the critical path of the network. These results suggests an in-depth study of using linear programming and applying it to project networks to grant project managers more critical insight that may help them better achieve their respective objectives. This work may also be useful as the groundwork for further refinement and application for maintenance managers conducting day-to-day unit level maintenance operations.
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Date Issued
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2006
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Identifier
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CFE0001381, ucf:47008
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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/CFE0001381
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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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Injection-locked semiconductor lasers for realization of novel RF photonics components.
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Creator
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Hoghooghi, Nazanin, Delfyett, Peter, Likamwa, Patrick, Li, Guifang, Malocha, Donald, University of Central Florida
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Abstract / Description
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This dissertation details the work has been done on a novel resonant cavity linear interferometric modulator and a direct phase detector with channel filtering capability using injection-locked semiconductor lasers for applications in RF photonics. First, examples of optical systems whose performance can be greatly enhanced by using a linear intensity modulator are presented and existing linearized modulator designs are reviewed. The novel linear interferometric optical intensity modulator...
Show moreThis dissertation details the work has been done on a novel resonant cavity linear interferometric modulator and a direct phase detector with channel filtering capability using injection-locked semiconductor lasers for applications in RF photonics. First, examples of optical systems whose performance can be greatly enhanced by using a linear intensity modulator are presented and existing linearized modulator designs are reviewed. The novel linear interferometric optical intensity modulator based on an injection-locked laser as an arcsine phase modulator is introduced and followed by numerical simulations of the phase and amplitude response of an injection-locked semiconductor laser. The numerical model is then extended to study the effects of the injection ratio, nonlinear cavity response, depth of phase and amplitude modulation on the spur-free dynamic range of a semiconductor resonant cavity linear modulator. Experimental results of the performance of the linear modulator implemented with a multi-mode Fabry-Perot semiconductor laser as the resonant cavity are shown and compared with the theoretical model. The modulator performance using a vertical cavity surface emitting laser as the resonant cavity is investigated as well. Very low V? in the order of 1 mV, multi-gigahertz bandwidth (-10 dB bandwidth of 5 GHz) and a spur-free dynamic range of 120 dB.Hz2/3 were measured directly after the modulator. The performance of the modulator in an analog link is experimentally investigated and the results show no degradation of the modulator linearity after a 1 km of SMF.The focus of the work then shifts to applications of an injection-locked semiconductor laser as a direct phase detector and channel filter. This phase detection technique does not require a local oscillator. Experimental results showing the detection and channel filtering capability of an injection-locked semiconductor diode laser in a three channel system are shown. The detected electrical signal has a signal-to-noise ratio better than 60 dB/Hz. In chapter 4, the phase noise added by an injection-locked vertical cavity surface emitting laser is studied using a self-heterodyne technique. The results show the dependency of the added phase noise on the injection ratio and detuning frequency. The final chapter outlines the future works on the linear interferometric intensity modulator including integration of the modulator on a semiconductor chip and the design of the modulator for input pulsed light.
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Date Issued
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2012
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Identifier
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CFE0004385, ucf:49368
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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/CFE0004385
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Title
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Evaluating Corrosion Control Alternatives for a Reverse Osmosis, Nanofiltration and Anion-Exchange Blended Water Supply.
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Creator
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Wilder, Rebecca, Duranceau, Steven, Randall, Andrew, Zhang, Husen, University of Central Florida
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Abstract / Description
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The research reported herein describes the study activities performed by University of Central Florida (UCF) on behalf of the Town of Jupiter Water Utilities (Town). The Town recently changed its water treatment operations from a combination of reverse osmosis (RO), lime softening (LS) and anion-exchange (IX) to a combination of RO, IX and nanofiltration (NF). Although this treatment change provided enhanced water to the surrounding community in terms of better contaminant removal and reduced...
Show moreThe research reported herein describes the study activities performed by University of Central Florida (UCF) on behalf of the Town of Jupiter Water Utilities (Town). The Town recently changed its water treatment operations from a combination of reverse osmosis (RO), lime softening (LS) and anion-exchange (IX) to a combination of RO, IX and nanofiltration (NF). Although this treatment change provided enhanced water to the surrounding community in terms of better contaminant removal and reduced DBP formation potential, integration of the NF process altered finished water quality parameters including pH, alkalinity and hardness. There was concern that these changes could result in secondary impacts related to accelerated corrosion of distribution system components and subsequent regulatory compliance. In addition, replacement of the LS process altered the in-plant blending operations by creating an unstable intermediate blend composed of RO and IX waters. There were concerns that this intermediate blend was affecting the integrity of in-plant hydraulic conveyance components.UCF developed a corrosion monitoring study to assess the potential impacts related to internal corrosion, water quality and regulatory compliance after integrating NF into the existing water supply. The intended purpose was to further highlight the complexities of corrosion, describe a unique approach to corrosion monitoring as well as offer various recommendations for corrosion control in a system that relies on a blended water supply. Research was conducted in three phases to address the in-plant and distribution system corrosion issues separately and identify appropriate corrosion control treatment alternatives. The three test phases included: a baseline conditions assessment to compare corrosion of the intermediate RO-IX blend with the finished water blend (RO-IX-NF); an in-plant corrosion control evaluation; and a distribution system corrosion control evaluation.A test apparatus was constructed and operated at the Town's facilities to monitor corrosion activity of mild steel, copper and lead solder metal components. The test apparatus consisted of looped PVC pipe segments housed with electrochemical probes and metal coupons to monitor corrosion rates of the metallic components. Electrochemical probes containing metal electrodes were used to obtain instantaneous corrosion rates by means of the Linear Polarization Resistance (LPR) technique while the metal coupons were gravimetrically evaluated for weight loss. The electrochemical probes permitted daily monitoring of each metal's corrosion rates while metal coupons were analyzed at the conclusion of testing and used for comparison. Different test waters flowed through the corrosion rack according to each test phase and relative corrosion rates were compared to evaluate corrosion control techniques.Study findings indicated that the intermediate blend was more corrosive, in general, then the final blend; however, research also indicated that the final blend of water was increasing lead and copper concentrations within the distribution system. An orthophosphate corrosion inhibitor was evaluated for in-plant corrosion control. The inhibitor's performance was assessed by comparing mild steel corrosion rates with and without the chemical. In addition, secondary impacts related to introduction of the chemical were evaluated by pre-corroding the metallic components prior to the introduction of the inhibitor. Results indicated that the inhibitor marginally decreased corrosion rates and increased the turbidity of the water supply. Based on these observations, it was concluded that the inhibitor was not a viable solution for in-plant corrosion control. To resolve in-plant corrosion issues, recommendations were made for modification of in-plant blending operations to eliminate the corrosive intermediate blend from the process allowing the RO, IX and NF treated waters to be blended in a common location. The effectiveness of a poly/ortho blended phosphate chemical inhibitor was evaluated for reducing lead and copper corrosion to resolve distribution corrosion issues. A 50/50 poly/ortho blend was selected because of its analogous use in similar municipal water facilities. Metallic corrosion rates, particularly lead and copper, were compared with and without the inhibitor to assess the performance of the chemical. Like the previous test phase, the metallic components were pre-corroded prior to the chemical's introduction to determine if secondary impacts could result from its presence. Results indicated that lead and copper corrosion rates were lower in the presence of the inhibitor, and secondary impacts related to increased turbidity were not observed for this chemical. Based on these results, it was recommended that a poly/ortho blended phosphate be used to decrease lead and copper corrosion within the Town's distribution system.
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Date Issued
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2012
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Identifier
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CFE0004460, ucf:49349
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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/CFE0004460
Pages