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- Title
- MODELING SCENES AND HUMAN ACTIVITIES IN VIDEOS.
- Creator
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Basharat, Arslan, Shah, Mubarak, University of Central Florida
- Abstract / Description
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In this dissertation, we address the problem of understanding human activities in videos by developing a two-pronged approach: coarse level modeling of scene activities and fine level modeling of individual activities. At the coarse level, where the resolution of the video is low, we rely on person tracks. At the fine level, richer features are available to identify different parts of the human body, therefore we rely on the body joint tracks. There are three main goals of this dissertation: ...
Show moreIn this dissertation, we address the problem of understanding human activities in videos by developing a two-pronged approach: coarse level modeling of scene activities and fine level modeling of individual activities. At the coarse level, where the resolution of the video is low, we rely on person tracks. At the fine level, richer features are available to identify different parts of the human body, therefore we rely on the body joint tracks. There are three main goals of this dissertation: (1) identify unusual activities at the coarse level, (2) recognize different activities at the fine level, and (3) predict the behavior for synthesizing and tracking activities at the fine level. The first goal is addressed by modeling activities at the coarse level through two novel and complementing approaches. The first approach learns the behavior of individuals by capturing the patterns of motion and size of objects in a compact model. Probability density function (pdf) at each pixel is modeled as a multivariate Gaussian Mixture Model (GMM), which is learnt using unsupervised expectation maximization (EM). In contrast, the second approach learns the interaction of object pairs concurrently present in the scene. This can be useful in detecting more complex activities than those modeled by the first approach. We use a 14-dimensional Kernel Density Estimation (KDE) that captures motion and size of concurrently tracked objects. The proposed models have been successfully used to automatically detect activities like unusual person drop-off and pickup, jaywalking, etc. The second and third goals of modeling human activities at the fine level are addressed by employing concepts from theory of chaos and non-linear dynamical systems. We show that the proposed model is useful for recognition and prediction of the underlying dynamics of human activities. We treat the trajectories of human body joints as the observed time series generated from an underlying dynamical system. The observed data is used to reconstruct a phase (or state) space of appropriate dimension by employing the delay-embedding technique. This transformation is performed without assuming an exact model of the underlying dynamics and provides a characteristic representation that will prove to be vital for recognition and prediction tasks. For recognition, properties of phase space are captured in terms of dynamical and metric invariants, which include the Lyapunov exponent, correlation integral, and correlation dimension. A composite feature vector containing these invariants represents the action and will be used for classification. For prediction, kernel regression is used in the phase space to compute predictions with a specified initial condition. This approach has the advantage of modeling dynamics without making any assumptions about the exact form (polynomial, radial basis, etc.) of the mapping function. We demonstrate the utility of these predictions for human activity synthesis and tracking.
Show less - Date Issued
- 2009
- Identifier
- CFE0002897, ucf:48042
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002897
- Title
- DATA MINING METHODS FOR MALWARE DETECTION.
- Creator
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Siddiqui, Muazzam, Wang, Morgan, University of Central Florida
- Abstract / Description
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This research investigates the use of data mining methods for malware (malicious programs) detection and proposed a framework as an alternative to the traditional signature detection methods. The traditional approaches using signatures to detect malicious programs fails for the new and unknown malwares case, where signatures are not available. We present a data mining framework to detect malicious programs. We collected, analyzed and processed several thousand malicious and clean programs to...
Show moreThis research investigates the use of data mining methods for malware (malicious programs) detection and proposed a framework as an alternative to the traditional signature detection methods. The traditional approaches using signatures to detect malicious programs fails for the new and unknown malwares case, where signatures are not available. We present a data mining framework to detect malicious programs. We collected, analyzed and processed several thousand malicious and clean programs to find out the best features and build models that can classify a given program into a malware or a clean class. Our research is closely related to information retrieval and classification techniques and borrows a number of ideas from the field. We used a vector space model to represent the programs in our collection. Our data mining framework includes two separate and distinct classes of experiments. The first are the supervised learning experiments that used a dataset, consisting of several thousand malicious and clean program samples to train, validate and test, an array of classifiers. In the second class of experiments, we proposed using sequential association analysis for feature selection and automatic signature extraction. With our experiments, we were able to achieve as high as 98.4% detection rate and as low as 1.9% false positive rate on novel malwares.
Show less - Date Issued
- 2008
- Identifier
- CFE0002303, ucf:47870
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002303
- Title
- Driving Towards Sustainability: A Case Study of the Facilitators and Inhibitors of Electrifying Drive Tourism within the United States National Park System.
- Creator
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Templeton, Amanda, Fjelstul, Jill, Fyall, Alan, Tasci, Asli, Prideaux, Bruce, University of Central Florida
- Abstract / Description
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Drive tourism has proven to be a popular sub-sector of the tourism industry, given its ability to offer tourists a substantial amount of flexibility and sense of freedom in determining what destinations to explore. Few studies have examined the future of the drive tourism with consideration to changing technologies and growing awareness to the impact of carbon emissions and Green House Gasses. Research has recently begun to examine the ecological consequences of park transportation systems....
Show moreDrive tourism has proven to be a popular sub-sector of the tourism industry, given its ability to offer tourists a substantial amount of flexibility and sense of freedom in determining what destinations to explore. Few studies have examined the future of the drive tourism with consideration to changing technologies and growing awareness to the impact of carbon emissions and Green House Gasses. Research has recently begun to examine the ecological consequences of park transportation systems. Some of these problems can be seen within the United States National Park System (NPS), as various park units are experiencing problems related to infrastructure and preservation of sites. As transportation plays an integral role within the NPS, the impacts of drive tourism must be considered. The study is founded on the premise that electric vehicles and electric vehicle charging stations will reduce GHG emissions, thereby increasing sustainability, supporting sustainable tourism and sustainable drive tourism within the NPS. In an effort to promote sustainable transportation efforts throughout the NPS this study investigates the facilitators that enable an EV infrastructure in some parks and inhibitors for other parks that have yet to develop an EV infrastructure. A qualitative methodology was adopted for this study. Data were analyzed using NVivo with findings being presented in case study format. The study, which offers a conceptual model and offers new definitions for electric vehicles and electric vehicle infrastructure within nature based tourism context, finds key facilitators to include: collaborative efforts through public/private partnerships, strong leadership within the NPS, and availability of funding; major inhibitors being: geography of park unit, lack cultural openness within NPS park unit, and regulatory policies. Current research has given little attention to the future sustainability of drive tourism, allowing this study to add to the academic body of knowledge. Additionally, the suggestions offered in the study are relevantly timed to what is happening within the industry.
Show less - Date Issued
- 2018
- Identifier
- CFE0007107, ucf:51967
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007107
- Title
- Factors Contributing to Low Adequate Prenatal Care Rates in Orange County, Florida.
- Creator
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Daniel, Lauren, Donley, Amy, Hinojosa, Melanie, University of Central Florida
- Abstract / Description
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In 2017, only 56% of births in Orange County, Florida, received adequate prenatal care(-)care that has been shown to prevent maternal and infant death. The Florida Department of Health uses the Kotelchuck Index to determine care adequacy. This index rates care adequacy based on when the mother first receives care, and how many recommended appointments she attends. Prenatal care is rated (")inadequate(") if it starts after the fourth month of pregnancy, and/or if less than half of the...
Show moreIn 2017, only 56% of births in Orange County, Florida, received adequate prenatal care(-)care that has been shown to prevent maternal and infant death. The Florida Department of Health uses the Kotelchuck Index to determine care adequacy. This index rates care adequacy based on when the mother first receives care, and how many recommended appointments she attends. Prenatal care is rated (")inadequate(") if it starts after the fourth month of pregnancy, and/or if less than half of the recommended appointments are attended. Receiving earlier and consistent prenatal care has been shown to be an effective way to improve birth outcomes.In Florida, counties that have low adequate prenatal care rates like Orange County's tend to be less populous and rural. However, Orange County stands out with its large population of 1.3 million and more urban environment; other Florida counties similar in population and environment to Orange tend to have rates like that of the state's, at approximately 70%.The objective of this study is to determine which factors contribute most significantly to prenatal care inadequacy in Orange, Duval, Hillsborough, Miami-Dade, and Pinellas counties; determine the differences between the most significant factors in Orange County and those in the other four counties; and to determine if residing in Orange County in of itself a risk factor for inadequate prenatal care, using logistic regression. By identifying factors that may lead to low adequacy rates, interventions intended to increase care adequacy in Orange County can be better targeted towards populations in need.
Show less - Date Issued
- 2019
- Identifier
- CFE0007447, ucf:52715
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007447
- Title
- A modeling framework of brittle and ductile fractures coexistence in composites.
- Creator
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Qiao, Yangyang, Bai, Yuanli, Gou, Jihua, Kassab, Alain, Gordon, Ali, An, Linan, University of Central Florida
- Abstract / Description
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In order to reduce the weight of automobiles and aircrafts, lightweight materials, such as aluminum alloy, advanced high strength steel, composite materials, are widely used to replace the traditional materials like mild steel. Composite materials are complicated in material mechanical properties and less investigated compared to metallic materials. Engineering composites can be categorized into polymer matrix composites (PMCs), metal matrix composites (MMCs) and ceramic matrix composites ...
Show moreIn order to reduce the weight of automobiles and aircrafts, lightweight materials, such as aluminum alloy, advanced high strength steel, composite materials, are widely used to replace the traditional materials like mild steel. Composite materials are complicated in material mechanical properties and less investigated compared to metallic materials. Engineering composites can be categorized into polymer matrix composites (PMCs), metal matrix composites (MMCs) and ceramic matrix composites (CMCs) according to their matrix materials.A set of mechanical experiments ranging from micro scale (single fiber composite and thin film composite) to macro scale (PMCs and MMCs) were conducted to fully understand the material behavior of composite materials. Loading conditions investigated includes uniaxial tension, three-point bending, uniaxial compression, simple shear, tension combined with shear, and compression combined with shear.For single fiber composite and thin-film composite, details of each composition are modelled. For the PMCs and MMCs which have plenty of reinforcements like fibers and particles, the details of the composition of structures cannot be modelled due to the current limitations of computing power. A mechanics framework of composite materials including elasticity, plasticity, failure initiation and post failure softening is proposed and applied to two types of composite materials.Uniaxial tension loading is applied to several single fiber composites and thin film composites. A surprising phenomenon, controllable and sequential fragmentation of the brittle fiber to produce uniformly sized rods along meters of polymer cladding, rather than the expected random or chaotic fragmentation, is observed with a necking propagation process. A combination of necking propagation model, fiber cracking model and interfacial model are proposed and applied to the finite element simulations. Good predictions of necking propagation and uniform fragmentation phenomenon are achieved. This modeling method of the micro-scale phenomenon reveals the physics inside composites in micro scale and helps the understanding of the process of nano fragmentation.Unidirectional carbon fiber composites were tested under multi-axial loading conditions including tensile/compression/shear loadings along and perpendicular to the fiber direction. Compression dominated tests showed a brittle fracture mode like local kicking/buckling, while tension dominated tests showed a fracture mode like delamination and fiber breakage. Simple shear tests with displacement control showed matrix material hardening and softening before total failure. The proposed modeling framework is successfully applied to the PMCs. A new parameter ? was introduced to represent different loading conditions of PMCs. Numerical simulations using finite element method well duplicated the anisotropic elasticity and plasticity of this material. Failure features like delamination was simulated using cohesive surface feature. It is also applied to carbon fiber composite laminates to further validate the proposed model.A round of experimental study on high volume fraction of metallic matrix nano composites was conducted, including uniaxial tension, uniaxial compression, and three-point bending. The example materials were two magnesium matrix composites reinforced with 10 and 15% vol. SiC particles (50nm size). Brittle fracture mode was exhibited under uniaxial tension and three-point bending, while shear dominated ductile fracture mode (up to 12% fracture strain) was observed under uniaxial compression. Transferring the Modified Mohr Coulomb (MMC) ductile fracture model to the stress based MMC model (sMMC), the proposed modeling framework is applied to this material. This model has been demonstrated to be capable of predicting the coexistence of brittle and ductile fracture modes under different loading conditions for MMCs. Numerical simulations using finite element method well duplicated the material strength, fracture initiation sites and crack propagation modes of the Mg/SiC nano composites with a good accuracy.
Show less - Date Issued
- 2018
- Identifier
- CFE0007078, ucf:51977
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007078
- Title
- Ultra-Efficient Cascaded Buck-Boost Converter.
- Creator
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Ashok Pise, Anirudh, Batarseh, Issa, Mikhael, Wasfy, Sun, Wei, Kutkut, Nasser, University of Central Florida
- Abstract / Description
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This thesis presents various techniques to achieve ultra-high-efficiency for Cascaded-Buck-Boost converter. A rigorous loss model with component non linearity is developed and validated experimentally. An adaptive-switching-frequency control is discussed to optimize weighted efficiency. Some soft-switching techniques are discussed. A low-profile planar-nanocrystalline inductor is developed and various design aspects of core and copper design are discussed. Finite-element-method is used to...
Show moreThis thesis presents various techniques to achieve ultra-high-efficiency for Cascaded-Buck-Boost converter. A rigorous loss model with component non linearity is developed and validated experimentally. An adaptive-switching-frequency control is discussed to optimize weighted efficiency. Some soft-switching techniques are discussed. A low-profile planar-nanocrystalline inductor is developed and various design aspects of core and copper design are discussed. Finite-element-method is used to examine and visualize the inductor design. By implementing the above, a peak efficiency of over 99.2 % is achieved with a power density of 6 kW/L and a maximum profile height of 7 mm is reported. This converter finds many applications because of its versatility: allowing bidirectional power flow and the ability to step-up or step-down voltages in either direction.
Show less - Date Issued
- 2017
- Identifier
- CFE0007277, ucf:52181
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007277
- Title
- Fusing Freight Analysis Framework and Transearch Data: An Econometric Data Fusion Approach.
- Creator
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Momtaz, Salah Uddin, Eluru, Naveen, Abdel-Aty, Mohamed, Anowar, Sabreena, Zheng, Qipeng, University of Central Florida
- Abstract / Description
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A major hurdle in freight demand modeling has always been the lack of adequate data on freight movements for different industry sectors for planning applications. Freight Analysis Framework (FAF), and Transearch (TS) databases contain annualized commodity flow data. The primary motivation for our study is the development of a fused database from FAF and TS to realize transportation network flows at a fine spatial resolution (county-level) while accommodating for production and consumption...
Show moreA major hurdle in freight demand modeling has always been the lack of adequate data on freight movements for different industry sectors for planning applications. Freight Analysis Framework (FAF), and Transearch (TS) databases contain annualized commodity flow data. The primary motivation for our study is the development of a fused database from FAF and TS to realize transportation network flows at a fine spatial resolution (county-level) while accommodating for production and consumption behavioral trends (provided by TS). Towards this end, we formulate and estimate a joint econometric model framework grounded in maximum likelihood approach to estimate county-level commodity flows. The algorithm is implemented for the commodity flow information from 2012 FAF and 2011 TS databases to generate transportation network flows for 67 counties in Florida. The data fusion process considers several exogenous variables including origin-destination indicator variables, socio-demographic and socio-economic indicators, and transportation infrastructure indicators. Subsequently, the algorithm is implemented to develop freight flows for the Florida region considering inflows and outflows across the US and neighboring countries. The base year models developed are employed to predict future year data for years 2015 through 2040 in 5-year increments at the same spatial level. Furthermore, we disaggregate the county level flows obtained from algorithm to a finer resolution - statewide transportation analysis zone (SWTAZ) defined by the FDOT. The disaggregation process allocates truck-based commodity flows from a 79-zone system to an 8835-zone system. A two-stage factor multiplication method is proposed to disaggregate the county flow to SWTAZ flow. The factors are estimated both at the origin and destination level using a random utility factional split model approach. Eventually, we conducted a sensitivity analysis of the parameterization by evaluating the model structure for different numbers of intermediate stops in a route and/or the number of available routes for the origin-destinations.
Show less - Date Issued
- 2018
- Identifier
- CFE0007763, ucf:52384
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007763
- Title
- The AfterMath: A Culturally Responsive Mathematical Intervention to Aid Students Affected by Natural Disasters.
- Creator
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Kurtz, Brianna, Haciomeroglu, Erhan, Bush, Sarah, Safi, Farshid, Biraimah, Karen, University of Central Florida
- Abstract / Description
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On September 20, 2017, Hurricane Maria struck the island of Puerto Rico. The damage was extensive, and many people found themselves to be natural disaster refugees. As a result, schools in Central Florida saw an influx of new students who had their educations interrupted by the disaster and now were resuming school in a new language of instruction. These students not only faced linguistic challenges but also academic differences due to the high prevalence of poverty and the effects of...
Show moreOn September 20, 2017, Hurricane Maria struck the island of Puerto Rico. The damage was extensive, and many people found themselves to be natural disaster refugees. As a result, schools in Central Florida saw an influx of new students who had their educations interrupted by the disaster and now were resuming school in a new language of instruction. These students not only faced linguistic challenges but also academic differences due to the high prevalence of poverty and the effects of neocolonialism in their previous schooling. This mixed methods study implemented an intensive intervention in probability to aid students in developing mathematical understanding and forming meaningful connections. Student participants, who had been affected by Hurricane Maria, were now attending a public high school and were paired one-on-one with a bilingual, mathematically high performing student mentor to complete culturally responsive, bilingual probability tasks. Data collection occurred over the course of six weeks in fall 2019. Both mentor and mentee students participated in focus group interviews, and the mentees completed a probability pre-test and post-test. Student participants were found to have statistically significant increases in the understanding of probability concepts when comparing pre-intervention and post-intervention results, with the understanding and usage of the multiplication rule showing the most significant improvement. Both mentors and mentees reported feeling a stronger sense of unity and belonging post-intervention as well as improvement in bilingual academic vocabulary. With the impact of natural disasters on the rise, implications of this study include its adaption to respond to future displaced students as they resume schooling post-interruption in Central Florida and beyond.
Show less - Date Issued
- 2019
- Identifier
- CFE0007828, ucf:52820
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007828
- Title
- Surface Measurements and Predictions of Full-Coverage Film Cooling.
- Creator
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Natsui, Gregory, Kapat, Jayanta, Raghavan, Seetha, Vasu Sumathi, Subith, University of Central Florida
- Abstract / Description
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Full-coverage film cooling is investigated both experimentally and numerically. First,surface measurements local of adiabatic film cooling eeffectiveness and heat transfer augmentation for four different arrays are described. Reported next is a comparison between two very common turbulence models, Realizable k-epsilon and SST k-omega, and their ability to predict local film cooling effectiveness throughout a full-coverage array.The objective of the experimental study is the quantification of...
Show moreFull-coverage film cooling is investigated both experimentally and numerically. First,surface measurements local of adiabatic film cooling eeffectiveness and heat transfer augmentation for four different arrays are described. Reported next is a comparison between two very common turbulence models, Realizable k-epsilon and SST k-omega, and their ability to predict local film cooling effectiveness throughout a full-coverage array.The objective of the experimental study is the quantification of local heat transferaugmentation and adiabatic film cooling effectiveness for four surfaces cooled by large, both in hole count and in non-dimensional spacing, arrays of film cooling holes. The four arrays are of two different hole-to-hole spacings (P=D = X=D = 14.5; 19.8) and two different hole inclination angles (alpha = 30°; 45°), with cylindrical holes compounded relative to the flow(beta = 45°) and arranged in a staggered configuration. Arrays of up to 30 rows are tested so that the superposition effect of the coolant film can be studied. In addition, shortened arrays of up to 20 rows of coolant holes are also tested so that the decay of the coolant film following injection can be studied.Levels of laterally averaged effectiveness reach values as high as η = 0.5, and are not yet at the asymptotic limit even after 20 - 30 rows of injection for all cases studied. Levels of heat transfer augmentation asymptotically approach values of h=h0 ≈ 1.35 rather quickly, only after 10 rows. It is conjectured that the heat transfer augmentation levels off very quickly due to the boundary layer reaching an equilibrium in which the perturbation from additional film rows has reached a balance with the damping effect resulting from viscosity. The levels of laterally averaged adiabatic film cooling effectiveness far exceeding eta = 0.5 aremuch higher than expected. The heat transfer augmentation levels off quickly as opposed tothe film effectiveness which continues to rise (although asymptotically) at large row numbers. This ensures that an increased row count represents coolant well spent.The numerical predictions are carried out in order to test the ability of the two mostcommon turbulence models to properly predict full-coverage film cooling. The two models chosen, Realizable k-epsilon (RKE) and Shear Stress Transport k-omega (SSTKW), areboth two-equation models coupled with Reynolds Averaged governing equations which makeseveral gross physical assumptions and require several empirical values. Hence, the modelsare not expected to provide perfect results. However, very good average values are seen tobe obtained through these simple models. Using RKE in order to model full-coverage filmcooling will yield results with 30% less error than selecting SSTKW.
Show less - Date Issued
- 2012
- Identifier
- CFE0004580, ucf:49221
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004580
- Title
- Experimental study and modeling of mechanical micro-machining of particle reinforced heterogeneous materials.
- Creator
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Liu, Jian, Xu, Chengying, An, Linan, Gordon, Ali, Bai, Yuanli, Gong, Xun, University of Central Florida
- Abstract / Description
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This study focuses on developing explicit analytical and numerical process models for mechanical micro-machining of heterogeneous materials. These models are used to select suitable process parameters for preparing and micro-machining of these advanced materials. The material system studied in this research is Magnesium Metal Matrix Composites (Mg-MMCs) reinforced with nano-sized and micro-sized silicon carbide (SiC) particles.This research is motivated by increasing demands of miniaturized...
Show moreThis study focuses on developing explicit analytical and numerical process models for mechanical micro-machining of heterogeneous materials. These models are used to select suitable process parameters for preparing and micro-machining of these advanced materials. The material system studied in this research is Magnesium Metal Matrix Composites (Mg-MMCs) reinforced with nano-sized and micro-sized silicon carbide (SiC) particles.This research is motivated by increasing demands of miniaturized components with high mechanical performance in various industries. Mg-MMCs become one of the best candidates due to its light weight, high strength, and high creep/wear resistance. However, the improved strength and abrasive nature of the reinforcements bring great challenges for the subsequent micro-machining process.Systematic experimental investigations on the machinability of Mg-MMCs reinforced with SiC nano-particles have been conducted. The nanocomposites containing 5 Vol.%, 10 Vol.% and 15 Vol.% reinforcements, as well as pure magnesium, are studied by using the Design of Experiment (DOE) method. Cutting forces, surface morphology and surface roughness are characterized to understand the machinability of the four materials. Based on response surface methodology (RSM) design, experimental models and related contour plots have been developed to build a connection between different materials properties and cutting parameters. Those models can be used to predict the cutting force, the surface roughness, and then optimize the machining process.An analytical cutting force model has been developed to predict cutting forces of Mg-MMCs reinforced with nano-sized SiC particles in the micro-milling process. This model is different from previous ones by encompassing the behaviors of reinforcement nanoparticles in three cutting scenarios, i.e., shearing, ploughing and elastic recovery. By using the enhanced yield strength in the cutting force model, three major strengthening factors are incorporated, including load-bearing effect, enhanced dislocation density strengthening effect and Orowan strengthening effect. In this way, the particle size and volume fraction, as significant factors affecting the cutting forces, are explicitly considered. In order to validate the model, various cutting conditions using different size end mills (100 (&)#181;m and 1 mm dia.) have been conducted on Mg-MMCs with volume fraction from 0 (pure magnesium) to 15 Vol.%. The simulated cutting forces show a good agreement with the experimental data. The proposed model can predict the major force amplitude variations and force profile changes as functions of the nanoparticles' volume fraction. Next, a systematic evaluation of six ductile fracture models has been conducted to identify the most suitable fracture criterion for micro-scale cutting simulations. The evaluated fracture models include constant fracture strain, Johnson-Cook, Johnson-Cook coupling criterion, Wilkins, modified Cockcroft-Latham, and Bao-Wierzbicki fracture criterion. By means of a user material subroutine (VUMAT), these fracture models are implemented into a Finite Element (FE) orthogonal cutting model in ABAQUS/Explicit platform. The local parameters (stress, strain, fracture factor, velocity fields) and global variables (chip morphology, cutting forces, temperature, shear angle, and machined surface integrity) are evaluated. Results indicate that by coupling with the damage evolution, the capability of Johnson-Cook and Bao-Wierzbicki can be further extended to predict accurate chip morphology. Bao-Wierzbiki-based coupling model provides the best simulation results in this study. The micro-cutting performance of MMCs materials has also been studied by using FE modeling method. A 2-D FE micro-cutting model has been constructed. Firstly, homogenized material properties are employed to evaluate the effect of particles' volume fraction. Secondly, micro-structures of the two-phase material are modeled in FE cutting models. The effects of the existing micro-sized and nano-sized ceramic particles on micro-cutting performance are carefully evaluated in two case studies. Results show that by using the homogenized material properties based on Johnson-Cook plasticity and fracture model with damage evolution, the micro-cutting performance of nano-reinforced Mg-MMCs can be predicted. Crack generation for SiC particle reinforced MMCs is different from their homogeneous counterparts; the effect of micro-sized particles is different from the one of nano-sized particles.In summary, through this research, a better understanding of the unique cutting mechanism for particle reinforced heterogeneous materials has been obtained. The effect of reinforcements on micro-cutting performance is obtained, which will help material engineers tailor suitable material properties for special mechanical design, associated manufacturing method and application needs. Moreover, the proposed analytical and numerical models provide a guideline to optimize process parameters for preparing and micro-machining of heterogeneous MMCs materials. This will eventually facilitate the automation of MMCs' machining process and realize high-efficiency, high-quality, and low-cost manufacturing of composite materials.
Show less - Date Issued
- 2012
- Identifier
- CFE0004570, ucf:49196
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004570
- Title
- LASER INDUCED BREAKDOWN SPECTROSCOPY FOR DETECTION OF ORGANIC RESIDUES: IMPACT OF AMBIENT ATMOSPHERE AND LASER PARAMETERS.
- Creator
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Brown, Christopher, Richardson, Martin, University of Central Florida
- Abstract / Description
-
Laser Induced Breakdown Spectroscopy (LIBS) is showing great potential as an atomic analytical technique. With its ability to rapidly analyze all forms of matter, with little-to-no sample preparation, LIBS has many advantages over conventional atomic emission spectroscopy techniques. With the maturation of the technologies that make LIBS possible, there has been a growing movement to implement LIBS in portable analyzers for field applications. In particular, LIBS has long been considered the...
Show moreLaser Induced Breakdown Spectroscopy (LIBS) is showing great potential as an atomic analytical technique. With its ability to rapidly analyze all forms of matter, with little-to-no sample preparation, LIBS has many advantages over conventional atomic emission spectroscopy techniques. With the maturation of the technologies that make LIBS possible, there has been a growing movement to implement LIBS in portable analyzers for field applications. In particular, LIBS has long been considered the front-runner in the drive for stand-off detection of trace deposits of explosives. Thus there is a need for a better understanding of the relevant processes that are responsible for the LIBS signature and their relationships to the different system parameters that are helping to improve LIBS as a sensing technology. This study explores the use of LIBS as a method to detect random trace amounts of specific organic materials deposited on organic or non-metallic surfaces. This requirement forces the limitation of single-shot signal analysis. This study is both experimental and theoretical, with a sizeable component addressing data analysis using principal components analysis to reduce the dimensionality of the data, and quadratic discriminant analysis to classify the data. In addition, the alternative approach of 'target factor analysis' was employed to improve detection of organic residues on organic substrates. Finally, a new method of characterizing the laser-induced plasma of organics, which should lead to improved data collection and analysis, is introduced. The comparison between modeled and experimental measurements of plasma temperatures and electronic density is discussed in order to improve the present models of low-temperature laser induced plasmas.
Show less - Date Issued
- 2011
- Identifier
- CFE0003708, ucf:48843
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003708
- Title
- Systems Analysis for Urban Water Infrastructure Expansion with Global Change Impact under Uncertainties.
- Creator
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Qi, Cheng, Chang, Ni-bin, Geiger, Christopher, Xanthopoulos, Petros, Wanielista, Martin, University of Central Florida
- Abstract / Description
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Over the past decades, cost-effectiveness principle or cost-benefit analysis has been employed oftentimes as a typical assessment tool for the expansion of drinking water utility. With changing public awareness of the inherent linkages between climate change, population growth and economic development, the addition of global change impact in the assessment regime has altered the landscape of traditional evaluation matrix. Nowadays, urban drinking water infrastructure requires careful long...
Show moreOver the past decades, cost-effectiveness principle or cost-benefit analysis has been employed oftentimes as a typical assessment tool for the expansion of drinking water utility. With changing public awareness of the inherent linkages between climate change, population growth and economic development, the addition of global change impact in the assessment regime has altered the landscape of traditional evaluation matrix. Nowadays, urban drinking water infrastructure requires careful long-term expansion planning to reduce the risk from global change impact with respect to greenhouse gas (GHG) emissions, economic boom and recession, as well as water demand variation associated with population growth and migration. Meanwhile, accurate prediction of municipal water demand is critically important to water utility in a fast growing urban region for the purpose of drinking water system planning, design and water utility asset management. A system analysis under global change impact due to the population dynamics, water resources conservation, and environmental management policies should be carried out to search for sustainable solutions temporally and spatially with different scales under uncertainties. This study is aimed to develop an innovative, interdisciplinary, and insightful modeling framework to deal with global change issues as a whole based on a real-world drinking water infrastructure system expansion program in Manatee County, Florida. Four intertwined components within the drinking water infrastructure system planning were investigated and integrated, which consists of water demand analysis, GHG emission potential, system optimization for infrastructure expansion, and nested minimax-regret (NMMR) decision analysis under uncertainties. In the water demand analysis, a new system dynamics model was developed to reflect the intrinsic relationship between water demand and changing socioeconomic environment. This system dynamics model is based on a coupled modeling structure that takes the interactions among economic and social dimensions into account offering a satisfactory platform. In the evaluation of GHG emission potential, a life cycle assessment (LCA) is conducted to estimate the carbon footprint for all expansion alternatives for water supply. The result of this LCA study provides an extra dimension for decision makers to extract more effective adaptation strategies. Both water demand forecasting and GHG emission potential were deemed as the input information for system optimization when all alternatives are taken into account simultaneously. In the system optimization for infrastructure expansion, a multiobjective optimization model was formulated for providing the multitemporal optimal facility expansion strategies. With the aid of a multi-stage planning methodology over the partitioned time horizon, such a systems analysis has resulted in a full-scale screening and sequencing with respect to multiple competing objectives across a suite of management strategies. In the decision analysis under uncertainty, such a system optimization model was further developed as a unique NMMR programming model due to the uncertainties imposed by the real-world problem. The proposed NMMR algorithm was successfully applied for solving the real-world problem with a limited scale for the purpose of demonstration.
Show less - Date Issued
- 2012
- Identifier
- CFE0004425, ucf:49354
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004425
- Title
- Evaluation and Modeling of the Safety of Open Road Tolling System.
- Creator
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Abuzwidah, Muamer, Abdel-Aty, Mohamed, Radwan, Ahmed, Uddin, Nizam, University of Central Florida
- Abstract / Description
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The goal of this thesis is to examine the traffic safety impact of upgrading Toll Plazas (TP) to Open Road Tolling (ORT). The ORT could enhance safety but could also pose some traffic safety concerns at Toll plazas. Crashes from eight years were investigated by evaluating the crash data before and after the implementation of the ORT.The study was conducted by using two approaches: 1) a simple before and after study and with a comparison group; 2) a modeling effort to help understand the...
Show moreThe goal of this thesis is to examine the traffic safety impact of upgrading Toll Plazas (TP) to Open Road Tolling (ORT). The ORT could enhance safety but could also pose some traffic safety concerns at Toll plazas. Crashes from eight years were investigated by evaluating the crash data before and after the implementation of the ORT.The study was conducted by using two approaches: 1) a simple before and after study and with a comparison group; 2) a modeling effort to help understand the relationship between the crash frequency and several important factors and circumstances such as injury severity, collision types, average daily traffic (ADT) and Toll plaza characteristics. The study investigated 11 Toll plazas on State Roads 408, 417, 528 and 429 that have been changed to the ORT design. Several maps showing the Toll plazas and identifying the relevant crash locations were generated. Negative Binomial (NB), Log Linear model and two-way contingency table were examined. Two log-linear models with three variables in each model with all possible two-way interactions were developed. Categorical data analysis of the 2009 and 2010 crash dataset was performed. In order to compare the differences in response between the crash frequency and a particular crash-related variable, odds ratios were computed. The effects of crash frequency and crash-related factors were examined, and interactions among them were considered. The results indicated significant relationships between the crash frequency and ADT, crash type and driver age.It is worth mentioning that the expressway network understudy was continuously experiencing constructions throughout the study period. There is indication that ORT reduced the total crash number; also there is indication of changing the crash types and locations; and the majority of crashes occurred at the diverging and merging areas and resulted in more severe crashes. More data may be needed to confirm these results especially after all constructions and upgrades are made.The Implementation of open road tolling, the locations of Toll plazas, Automatic Vehicle Identification (AVI) subscription rate, traffic demand, and plaza geometry all may have a high influence on traffic safety concerns at Toll plazas, as concluded from the negative Binomial Model's results. The changing of sign locations, reducing the speed limit, installing variable message signs, configuring plazas properly, and other considerations may be the solution to overcome the potential safety problems in the vicinity of Toll plazas.The change of design to ORT was proven to be an excellent solution to several traffic operation problems, including reducing congestion and improving traffic flow and capacity at Toll plazas. However, addressing safety concerns at Toll plazas should take priority.
Show less - Date Issued
- 2011
- Identifier
- CFE0004466, ucf:49330
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004466
- Title
- MIXED SIGNALS AT THE INTERSECTION: THE EFFECT OF ORGANIZATIONAL COMPOSITION ON RATINGS OF BLACK WOMEN'S MANAGEMENT SUITABILITY.
- Creator
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Bowens, Laticia, Fritzsche, Ph.D., Barbara, University of Central Florida
- Abstract / Description
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Historically, Black women's workplace experiences have been understudied, partially due to an implicit assumption that their experiences are subsumed by research on Black men and/or White women. This oversight is even more evident in the field of management. However, considerable attention has been given to the debate about whether Black women are at a double advantage (i.e., as supposed affirmative action "two-for-one bargains") or at a double disadvantage due to their double marginalizing...
Show moreHistorically, Black women's workplace experiences have been understudied, partially due to an implicit assumption that their experiences are subsumed by research on Black men and/or White women. This oversight is even more evident in the field of management. However, considerable attention has been given to the debate about whether Black women are at a double advantage (i.e., as supposed affirmative action "two-for-one bargains") or at a double disadvantage due to their double marginalizing characteristics. Empirical research in the area has found support for each side, furthering the debate, but also advancing an overly simplistic explanation for a set of experiences that is certainly much more complicated. Therefore, the purpose of this study was to investigate the conditions under which Black women, when seeking managerial employment, are at a double advantage or disadvantage, using Critical Race Feminism, Cox's Interactional Model of Cultural Diversity (IMCD; 1994), and theories of social categorization as the theoretical foundation. A 2 (sex) x 2 (race) x 2 (demographic composition of the workplace) between-subjects design was used to test the hypotheses that the Black female applicant would have a double disadvantage in a more demographically balanced organization and double advantage in an organization that is more White and male. Participants (N = 361) reviewed information about an organization (where demographic composition was manipulated) and three available management positions. They also reviewed a fictional professional networking profile of a job applicant where race and sex were manipulated through photos, and job qualifications and experience were held constant. Based on all of the information, they rated the applicant on his/her suitability for the jobs. Results of planned contrasts and ANOVAs showed partial support for the hypotheses. In the balanced organization, the Black female applicant was rated lower in suitability for entry-level management than the Black male and White female applicants. Likewise, she was rated higher than the Black male and White female applicants in the less diverse organization, when evaluated for upper-level management. Thus, the study clarifies the theories of double advantage and double disadvantage by identifying organizational composition as a moderator of the relationship between applicant race/sex and employment outcomes (i.e., management suitability ratings). The implications of these findings are discussed.
Show less - Date Issued
- 2011
- Identifier
- CFE0003761, ucf:48761
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003761
- Title
- DESIGN AND OPERATION OF STATIONARY DISTRIBUTED BATTERY MICRO-STORAGE SYSTEMS.
- Creator
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Al-Haj Hussein, Ala, Batarseh, Issa, University of Central Florida
- Abstract / Description
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Due to some technical and environmental constraints, expanding the current electric power generation and transmission system is being challenged by even increasing the deployment of distributed renewable generation and storage systems. Energy storage can be used to store energy from utility during low-demand (off-peak) hours and deliver this energy back to the utility during high-demand (on-peak) hours. Furthermore, energy storage can be used with renewable sources to overcome some of their...
Show moreDue to some technical and environmental constraints, expanding the current electric power generation and transmission system is being challenged by even increasing the deployment of distributed renewable generation and storage systems. Energy storage can be used to store energy from utility during low-demand (off-peak) hours and deliver this energy back to the utility during high-demand (on-peak) hours. Furthermore, energy storage can be used with renewable sources to overcome some of their limitations such as their strong dependence on the weather conditions, which cannot be perfectly predicted, and their unmatched or out-of-synchronization generation peaks with the demand peaks. Generally, energy storage enhances the performance of distributed renewable sources and increases the efficiency of the entire power system. Moreover, energy storage allows for leveling the load, shaving peak demands, and furthermore, transacting power with the utility grid. This research proposes an energy management system (EMS) to manage the operation of distributed grid-tied battery micro-storage systems for stationary applications when operated with and without renewable sources. The term "micro" refers to the capacity of the energy storage compared to the grid capacity. The proposed management system employs four dynamic models; economic model, battery model, and load and weather forecasting models. These models, which are the main contribution of this research, are used in order to optimally control the operation of the micro-storage system (MSS) to maximize the economic return for the end-user when operated in an electricity spot market system.
Show less - Date Issued
- 2011
- Identifier
- CFE0003964, ucf:48712
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003964
- Title
- ANALYSIS OF THE RELATIONSHIP BETWEEN THE LEVEL OF EDUCATIONAL COMPUTER GAME USE AND MILKEN EXEMPLAR TEACHER INSTRUCTIONAL STRATEGIES.
- Creator
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Dahan Marks, Yaela, Proctor, Michael, University of Central Florida
- Abstract / Description
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This research examines the nature and level of educational computer-based game techniques adoption by Milken Educator Award winning teachers in achieving success in their classrooms. The focus of the research is on their level of acceptance of educational computer-based games and the nature of game usage to increase student performance in the classroom. With Davis' (1985) Technology Acceptance Model (Davis, 1985) as the conceptual framework, the research also examines how teachers'...
Show moreThis research examines the nature and level of educational computer-based game techniques adoption by Milken Educator Award winning teachers in achieving success in their classrooms. The focus of the research is on their level of acceptance of educational computer-based games and the nature of game usage to increase student performance in the classroom. With Davis' (1985) Technology Acceptance Model (Davis, 1985) as the conceptual framework, the research also examines how teachers' perceptions of educational computer-based games influence their willingness to incorporate these teaching methods in their classroom. The approach utilizes a descriptive survey to develop and evaluate responses from exemplar teachers about the level and nature of their use (or lack thereof) of educational computer-based games and implementation in the classroom. Further, this research seeks to identify successful and unsuccessful techniques in the use of educational computer-based games in the classroom. In addition, data collection and analysis will seek to identify the strength of relationships between content-specific educational computer-based games and subject; educational computer-based games and gender; educational computer-based games and age; etc. A teacher who is exemplary as defined by Milken Educator Awards possesses, "exceptional educational talent as evidenced by effective instructional practices and student learning results in the classroom and school". Survey findings are placed within the Technology Acceptance Model framework developed by Davis.
Show less - Date Issued
- 2011
- Identifier
- CFE0003682, ucf:48811
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003682
- Title
- A MODEL INTEGRATED MESHLESS SOLVER (MIMS) FOR FLUID FLOW AND HEAT TRANSFER.
- Creator
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Gerace, Salvadore, Kassab, Alain, University of Central Florida
- Abstract / Description
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Numerical methods for solving partial differential equations are commonplace in the engineering community and their popularity can be attributed to the rapid performance improvement of modern workstations and desktop computers. The ubiquity of computer technology has allowed all areas of engineering to have access to detailed thermal, stress, and fluid flow analysis packages capable of performing complex studies of current and future designs. The rapid pace of computer development, however,...
Show moreNumerical methods for solving partial differential equations are commonplace in the engineering community and their popularity can be attributed to the rapid performance improvement of modern workstations and desktop computers. The ubiquity of computer technology has allowed all areas of engineering to have access to detailed thermal, stress, and fluid flow analysis packages capable of performing complex studies of current and future designs. The rapid pace of computer development, however, has begun to outstrip efforts to reduce analysis overhead. As such, most commercially available software packages are now limited by the human effort required to prepare, develop, and initialize the necessary computational models. Primarily due to the mesh-based analysis methods utilized in these software packages, the dependence on model preparation greatly limits the accessibility of these analysis tools. In response, the so-called meshless or mesh-free methods have seen considerable interest as they promise to greatly reduce the necessary human interaction during model setup. However, despite the success of these methods in areas demanding high degrees of model adaptability (such as crack growth, multi-phase flow, and solid friction), meshless methods have yet to gain notoriety as a viable alternative to more traditional solution approaches in general solution domains. Although this may be due (at least in part) to the relative youth of the techniques, another potential cause is the lack of focus on developing robust methodologies. The failure to approach development from a practical perspective has prevented researchers from obtaining commercially relevant meshless methodologies which reach the full potential of the approach. The primary goal of this research is to present a novel meshless approach called MIMS (Model Integrated Meshless Solver) which establishes the method as a generalized solution technique capable of competing with more traditional PDE methodologies (such as the finite element and finite volume methods). This was accomplished by developing a robust meshless technique as well as a comprehensive model generation procedure. By closely integrating the model generation process into the overall solution methodology, the presented techniques are able to fully exploit the strengths of the meshless approach to achieve levels of automation, stability, and accuracy currently unseen in the area of engineering analysis. Specifically, MIMS implements a blended meshless solution approach which utilizes a variety of shape functions to obtain a stable and accurate iteration process. This solution approach is then integrated with a newly developed, highly adaptive model generation process which employs a quaternary triangular surface discretization for the boundary, a binary-subdivision discretization for the interior, and a unique shadow layer discretization for near-boundary regions. Together, these discretization techniques are able to achieve directionally independent, automatic refinement of the underlying model, allowing the method to generate accurate solutions without need for intermediate human involvement. In addition, by coupling the model generation with the solution process, the presented method is able to address the issue of ill-constructed geometric input (small features, poorly formed faces, etc.) to provide an intuitive, yet powerful approach to solving modern engineering analysis problems.
Show less - Date Issued
- 2010
- Identifier
- CFE0003299, ucf:48489
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003299
- Title
- ANALYSIS OF THE FLORIDAÂÂ'S SHOWCASE GREEN ENVIROHOME WATER/WASTEWATER SYSTEMS AND DEVELOPMENT OF A COST-BENEFIT GREEN ROOF OPTIMIZATION MODEL.
- Creator
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Rivera, Brian, Chang, Ni-Bin, University of Central Florida
- Abstract / Description
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The Florida Showcase Green Envirohome (FSGE) incorporates many green technologies. FSGE is built to meet or exceed 12 green building guidelines and obtain 8 green building certificates. The two-story 3292 ft2 home is a ÂÂ"Near Zero-Loss Home™ÂÂ", ÂÂ"Near Zero-Energy Home™ÂÂ", "Near Zero-Runoff Home™", and ÂÂ"Near Zero...
Show moreThe Florida Showcase Green Envirohome (FSGE) incorporates many green technologies. FSGE is built to meet or exceed 12 green building guidelines and obtain 8 green building certificates. The two-story 3292 ft2 home is a ÂÂ"Near Zero-Loss Home™ÂÂ", ÂÂ"Near Zero-Energy Home™ÂÂ", "Near Zero-Runoff Home™", and ÂÂ"Near Zero-Maintenance Home™ÂÂ". It is spawned from the consumer-driven necessity to build a home resistant to hurricanes, tornadoes, floods, fire, mold, termites, impacts, and even earthquakes given up to 500% increase in insurance premiums in natural disaster zones, the dwindling flexibility and coverage of insurance policies, and rising energy, water and maintenance costs (FSGE 2008). The FSGE captures its stormwater runoff from the green roof, metal roof and wood decking area and routes it to the sustainable water cistern. Graywater from the home (after being disinfected using ozone) is also routed to the sustainable water cistern. This water stored in the sustainable water cistern is used for irrigation of the green roof, ground level landscape, and for toilet flushing water. This study was done in two phases. During phase one, only stormwater runoff from the green roof, metal roof and wood decking area is routed to the sustainable water cistern. Then, during phase two, the water from the graywater system is added to the sustainable water cistern. The sustainable water cistern quality is analyzed during both phases to determine if the water is acceptable for irrigation and also if it is suitable for use as toilet flushing water. The water quality of the sustainable cistern is acceptable for irrigation. The intent of the home is to not pollute the environment, so as much nutrients as possible should be removed from the wastewater before it is discharged into the groundwater. Thus, the FSGE design is to evaluate a new on-site sewage treatment and disposal (OSTD) system which consists of a sorption media labeled as Bold and GoldTM filtration media. The Bold and GoldTM filtration media is a mixture of tire crumb and other materials. This new OSTD system has sampling ports through the system to monitor the wastewater quality as it passes through. Also, the effluent wastewater quality is compared to that of a conventional system on the campus of the University of Central Florida. The cost-benefit optimization model focused on designing a residential home which incorporated a green roof, cistern and graywater systems. This model had two forms, the base model and the grey linear model. The base model used current average cost of construction of materials and installation. The grey model used an interval for the cost of construction materials and green roof energy savings. Both models included a probabilistic term to describe the rainfall amount. The cost and energy operation of a typical Florida home was used as a case study for these models. Also, some of the parameters of the model were varied to determine their effect on the results. The modeling showed that the FSGE 4500 gallon cistern design was cost effective in providing irrigation water. Also, the green roof area could have been smaller to be cost effective, because the green roof cost is relatively much higher than the cost of a regular roof.
Show less - Date Issued
- 2010
- Identifier
- CFE0003297, ucf:48499
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003297
- Title
- APPLICATIONS OF AIRBORNE AND PORTABLE LIDAR IN THE STRUCTURAL DETERMINATION, MANAGEMENT, AND CONSERVATION OF SOUTHEASTERN U.S. PINE FORESTS.
- Creator
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Listopad, Claudia, Weishampel, John, University of Central Florida
- Abstract / Description
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Active remote sensing techniques, such as Light Detection and Ranging (LiDAR), have transformed the field of forestry and natural resource management in the last decade. Intensive assessments of forest resources and detailed structural assessments can now be accomplished faster and at multiple landscape scales. The ecological applications of having this valuable information at-hand are still only being developed. This work explores the use of two active remote sensing techniques, airborne and...
Show moreActive remote sensing techniques, such as Light Detection and Ranging (LiDAR), have transformed the field of forestry and natural resource management in the last decade. Intensive assessments of forest resources and detailed structural assessments can now be accomplished faster and at multiple landscape scales. The ecological applications of having this valuable information at-hand are still only being developed. This work explores the use of two active remote sensing techniques, airborne and portable LiDAR for forestry applications in a rapidly changing landscape, Southeastern Coastal Pine woodlands. Understanding the strengths and weaknesses of airborne and portable LiDAR, the tools used to extract structural information, and how to apply these to managing fire regimes are key to conserving unique upland pine ecosystems. Measuring habitat structure remotely and predicting habitat suitability through modeling will allow for the management of specific species of interest, such as threatened and endangered species. Chapter one focuses on the estimation of canopy cover and height measures across a variety of conditions of secondary upland pine and hardwood forests at Tall Timbers Research Station, FL. This study is unique since it uses two independent high resolution small-footprint LiDAR datasets (years 2002 and 2008) and extensive field plot and transect sampling for validation. Chapter One explores different tools available for metric derivation and tree extraction from discrete return airborne LiDAR data, highlighting strengths and weaknesses of each. Field and LiDAR datasets yielded better correlations for stand level comparisons, especially in canopy cover and mean height data extracted. Individual tree crown extraction from airborne LiDAR data significantly under-reported the total number of trees reported in the field datasets using either Fusion/LVD and LiDAR Analyst (Overwatch). Chapter two evaluates stand structure at the site of one of the longest running fire ecology studies in the US, located at Tall Timbers Research Station (TTRS) in the southeastern U.S. Small footprint high resolution discrete return LiDAR was used to provide an understanding of the impact of multiple disturbance regimes on forest structure, especially on the 3-dimensional spatial arrangement of multiple structural elements and structural diversity indices. LiDAR data provided sensitive detection of structural metrics, diversity, and fine-scale vertical changes in the understory and mid-canopy structure. Canopy cover and diversity indices were shown to be statistically higher in fire suppressed and less frequently burned plots than in 1- and 2-year fire interval treated plots, which is in general agreement with the increase from 2- to 3-year fire return interval being considered an "ecological threshold" for these systems (Masters et al. 2005). The results from this study highlight the value of the use of LiDAR in evaluating disturbance impacts on the three-dimensional structure of pine forest systems, particularly over large landscapes. Chapter three uses an affordable portable LiDAR system, first presented by Parker et al. (2004) and further modified for extra portability, to provide an understanding of structural differences between old-growth and secondary-growth forests in the Red Hills area of southwestern Georgia and North Florida. It also provides insight into the strengths and weaknesses in structural determination of ground-based portable systems in contrast to airborne LiDAR systems. Structural plot metrics obtained from airborne and portable LiDAR systems presented some similarities (i.e. canopy cover), but distinct differences appeared when measuring canopy heights (maximum and mean heights) using these different methods. Both the airborne and portable systems were able to provide gap detection and canopy cover estimation at the plot level. The portable system, when compared to the airborne LiDAR sensor, provides an underestimation of canopy cover in open forest systems (<50% canopy cover), but is more sensitive in detection of cover in hardwood woodland plots (>60% canopy cover). The strength of the portable LiDAR system lies in the detection of 3-dimensional fine structural changes (i.e. recruitment, encroachment) and with higher sensitivity in detecting lower canopy levels, often missed by airborne systems. Chapter four addresses a very promising application for fine-scale airborne LiDAR data, the creation of habitat suitability models for species of management and conservation concerns. This Chapter uses fine scale LiDAR metrics, such as canopy cover at various height strata, canopy height information, and a measure of horizontal vegetation distribution (clumped versus dispersed) to model the preferences of 10 songbirds of interest in southeast US woodlands. The results from this study highlight the rapidly changing nature of habitat conditions and how these impact songbird occurrence. Furthermore, Chapter four provides insight into the use of airborne LiDAR to provide specific management guidance to enhance the suitable habitat for 10 songbird species. The collection of studies presented here provides applied tools for the use of airborne and portable LiDAR for rapid assessment and responsive management in southeastern pine woodlands. The advantages of detecting small changes in three-dimensional vegetation structure and how these can impact habitat functionality and suitability for species of interest are explored throughout the next four chapters. The research presented here provides an original and important contribution in the application of airborne and portable LiDAR datasets in forest management and ecological studies.
Show less - Date Issued
- 2011
- Identifier
- CFE0003697, ucf:48831
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003697
- Title
- Spray Deposition Modeling of Carbon Nano-Inks.
- Creator
-
Sparkman, John, Gou, Jihua, Xu, Yunjun, Lin, Kuo-Chi, University of Central Florida
- Abstract / Description
-
Carbon nanopaper (CNP) exhibits qualities that are desirable for a number of applications such as flame retardancy, lightning protection, and flexible printed circuit boards. CNP has become a desired engineering material in many important sectors of industries such as space, automotive, aviation, and military. However the production of consistent thicknesses and dispersion remains a challenge for practical use. Most of the standard methods of production do not allow for continuous...
Show moreCarbon nanopaper (CNP) exhibits qualities that are desirable for a number of applications such as flame retardancy, lightning protection, and flexible printed circuit boards. CNP has become a desired engineering material in many important sectors of industries such as space, automotive, aviation, and military. However the production of consistent thicknesses and dispersion remains a challenge for practical use. Most of the standard methods of production do not allow for continuous applications or digital fabrication of the CNP. In this work, CNP is produced two different ways that allows for continuous production and digital fabrication. The continuous CNP making technique uses vacuum infiltration along with air atomization and a continuous drive belt system to produce a continuous roll of the CNP. This system is able to produce an 11 (&)#181;m (&)#177; 2 (&)#181;m CNP at 6 inches per min with an electrical resistivity of 59 ? per square. The major advantage of this production process is the ability to mass manufacture the CNP. Spray deposition modeling (SDM) is a digital fabrication process that uses a 12 array bubble jet nozzle attached to a digital control x-y plotter combined with a heated substrate which induces evaporation. This process is able to produce paper with variable thicknesses in defined locations. The maximum thickness of the CNP produced is 10 (&)#181;m with a resistivity of 95.7 ? per square. A strong advantage of this CNP production method comes from the ability to digitally print images. The controllable thickness and selective location printing presents an effective alternative to costlier methods and provides a solution to many geometrical CNP issues.
Show less - Date Issued
- 2015
- Identifier
- CFE0006231, ucf:51073
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006231
