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- Title
- Structured Light-Field Focusing 3D Density Measurements of A Supersonic Cone.
- Creator
-
Shigematsu, Ryonosuke, Ahmed, Kareem, Bhattacharya, Samik, Das, Tuhin, University of Central Florida
- Abstract / Description
-
This study describes three-dimensional (3D) quantitative visualization of density field in a supersonic flow around a cone spike. A measurement of the density gradient is conducted within a supersonic wind tunnel facility at the Propulsion and Energy Research Laboratory at the University of Central Florida utilizing Structured Light-Field Focusing Schlieren (SLLF). In conventional schlieren and Shadowgraph techniques, it is widely known that a complicated optical system is needed and yet...
Show moreThis study describes three-dimensional (3D) quantitative visualization of density field in a supersonic flow around a cone spike. A measurement of the density gradient is conducted within a supersonic wind tunnel facility at the Propulsion and Energy Research Laboratory at the University of Central Florida utilizing Structured Light-Field Focusing Schlieren (SLLF). In conventional schlieren and Shadowgraph techniques, it is widely known that a complicated optical system is needed and yet visualizable area depends on an effective diameter of lenses and mirrors. Unlike these techniques, SLLF is yet one of the same family as schlieren photography, it is capable of non-intrusive turbulent flow measurement with relatively low cost and easy-to-setup instruments. In this technique, cross-sectional area in the flow field that is parallel to flows can be observed while other schlieren methods measure density gradients in line-of-sight, meaning that it measures integrated density distribution caused by discontinuous flow parameters. To reconstruct a 3D model of shock structure, two-dimensional (2D) images are pictured to process in MATLAB. The ultimate goal of this study is to introduce a novel technique of SLLF and quantitative 3D shock structures generated around a cone spike to reveal the interaction between free-stream flow and the high-pressure region.
Show less - Date Issued
- 2018
- Identifier
- CFE0007096, ucf:51965
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007096
- Title
- INVESTIGATING FLOW, PRESENCE, AND ENGAGEMENT IN INDEPENDENT VIDEO GAME MECHANICS.
- Creator
-
Dunaj, Jon, McDaniel, Rudy, University of Central Florida
- Abstract / Description
-
Video games are being studied today more than ever before. The engagement that they generate with the user, if harnessed, is thought to have applications across numerous other fields. Educators especially wish to implement elements of gaming into supplemental activities to help further interest students in the learning process. Many claim that this is because classroom's today are in direct contradiction with the real home life of students. Student's today were born into the fast paced world...
Show moreVideo games are being studied today more than ever before. The engagement that they generate with the user, if harnessed, is thought to have applications across numerous other fields. Educators especially wish to implement elements of gaming into supplemental activities to help further interest students in the learning process. Many claim that this is because classroom's today are in direct contradiction with the real home life of students. Student's today were born into the fast paced world of the digital realm, frequently multi-tasking between watching television, playing games, doing homework, and socializing. As educators begin to create game like experiences to drive student engagement they will seek to create interactions that foster the psychological phenomena of flow, presence, and engagement. Each of these three processes helps play a key role in what makes video games the attention-grabbing medium that they are. When creating games it would be beneficial to know which type of game mechanics reinforce these phenomena the most. The goal of this study is to investigate, Super Meat Boy and Limbo, two very similar games with very different mechanical representations and see which game is more engaging in these three areas. Twenty- nine participants played one of the two games for forty-five minutes, completed three separate measurements, and were observed throughout the process. The results were analyzed and found one game to indeed be more engaging than the other.
Show less - Date Issued
- 2014
- Identifier
- CFH0004625, ucf:45268
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004625
- Title
- MULTIFUNCTIONAL NANOCOMPOSITES FOR HIGH DAMPING PERFORMANCE.
- Creator
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Algozzini, Lee, Gou, Jan, University of Central Florida
- Abstract / Description
-
Composite structures for aerospace and wind turbine applications are subjected to high acoustic and vibrational loading and exhibit very high amplitude displacements and thus premature failure. Materials with high damping or absorbing properties are crucially important to extend the life of structures. Traditional damping treatments are based on the combinations of viscoelastic, elastomeric, magnetic, and piezoelectric materials. In this work, the use of carbon nanofibers (CNFs) in the form...
Show moreComposite structures for aerospace and wind turbine applications are subjected to high acoustic and vibrational loading and exhibit very high amplitude displacements and thus premature failure. Materials with high damping or absorbing properties are crucially important to extend the life of structures. Traditional damping treatments are based on the combinations of viscoelastic, elastomeric, magnetic, and piezoelectric materials. In this work, the use of carbon nanofibers (CNFs) in the form of interconnected self-supportive paper as reinforcement can significantly improve damping performance. The interfacial friction is the primary source of energy dissipation in CNF paper based nanocomposites. The approach entailed making CNF paper by filtration of well-dispersed nanofibers under controlled processing conditions. The CNF paper was integrated into composite laminates using modified liquid composite molding processes including Resin Transfer Molding (RTM) and Vacuum Assisted Resin Transfer Molding (VARTM). The rheological and curing behaviors of the CNF-modified polymer resin were characterized with Viscometry and Differential Scanning Calorimetry (DSC). The process analysis in mold filling and pressure distribution was conducted using Control Volume Finite Element Method (CVFEM) in an attempt to optimize the quality of multifunctional nanocomposites. The mold filling simulation was validated with flow visualization in a transparent mold. Several tests were performed to study the damping properties of the fabricated composites including Dynamic Mechanical Analysis (DMA) and piezoceramic patch based vibration tests. It was found that the damping performance was significantly enhanced with the incorporation of carbon nanofibers into the composite structures.
Show less - Date Issued
- 2009
- Identifier
- CFE0002839, ucf:48078
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002839
- Title
- Theoretical Paschen's Law Model for Aerospace Vehicles: Validation Experiment.
- Creator
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Mulligan Aroche, Jaysen, Ahmed, Kareem, Kapat, Jayanta, Bhattacharya, Samik, University of Central Florida
- Abstract / Description
-
Aerospace vehicles often experience triboelectric charging while traversing the atmosphere. Triboelectric charging occurs when a material come into frictional contact with a different material. Aerospace vehicles triboelectrically charge due to frictional contact with dust and ice crystals suspended in the atmosphere. Launch vehicles traversing ice clouds in low-pressure atmosphere are especially prone to electrostatic discharge events (i.e. sparks). These conditions are hazardous and affect...
Show moreAerospace vehicles often experience triboelectric charging while traversing the atmosphere. Triboelectric charging occurs when a material come into frictional contact with a different material. Aerospace vehicles triboelectrically charge due to frictional contact with dust and ice crystals suspended in the atmosphere. Launch vehicles traversing ice clouds in low-pressure atmosphere are especially prone to electrostatic discharge events (i.e. sparks). These conditions are hazardous and affect the vehicle's launch commit criteria. In 2010, engineers from an ARES-I rocket launch reported concerns with triboelectric charging over their self-destruct system antenna. This concern was addressed by putting the antenna through harsh conditions in a laboratory environment. The need for laboratory testing could have been avoided if there was a mathematical model to predict these events. These discharge events can typically be predicted by the Classical Paschen's Law, which relates discharge voltage to pressure, material and distance between the charged and ground surfaces (i.e. electrodes). However, the Classical Paschen's Law does not capture any aerodynamic considerations such as large bulk flow and compressibility effects. It became apparent that a new model would be needed to predict a discharge voltage with aerodynamic considerations. This research focused on defining a theoretical model and providing experimental data to validate the model. The hypothesis of this work is that charged ions are removed too quickly for enough charge to build up and result in an electrostatic discharge at the voltage that is predicted by the Classical Paschen's Law. The wind tunnel testing for this experiment was conducted at the Center for Advanced Turbomachinery (&) Energy Research (CATER) facility. A charged electrode was exposed to flows at Mach numbers 1.5 to 3.5. It was found that the supersonic flow suppressed the electrostatic discharge events. The voltage required for an electrostatic discharge at supersonic conditions increased by a factor of three. The modified Paschen's Law can help in defining the launch commit criteria of aerospace vehicles.
Show less - Date Issued
- 2018
- Identifier
- CFE0007059, ucf:51994
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007059
- Title
- 4D-CT Lung Registration and its Application for Lung Radiation Therapy.
- Creator
-
Min, Yugang, Pattanaik, Sumanta, Hughes, Charles, Foroosh, Hassan, Santhanam, Anand, University of Central Florida
- Abstract / Description
-
Radiation therapy has been successful in treating lung cancer patients, but its efficacy is limited by the inability to account for the respiratory motion during treatment planning and radiation dose delivery. Physics-based lung deformation models facilitate the motion computation of both tumor and local lung tissue during radiation therapy. In this dissertation, a novel method is discussed to accurately register 3D lungs across the respiratory phases from 4D-CT datasets, which facilitates...
Show moreRadiation therapy has been successful in treating lung cancer patients, but its efficacy is limited by the inability to account for the respiratory motion during treatment planning and radiation dose delivery. Physics-based lung deformation models facilitate the motion computation of both tumor and local lung tissue during radiation therapy. In this dissertation, a novel method is discussed to accurately register 3D lungs across the respiratory phases from 4D-CT datasets, which facilitates the estimation of the volumetric lung deformation models. This method uses multi-level and multi-resolution optical flow registration coupled with thin plate splines (TPS), to address registration issue of inconsistent intensity across respiratory phases. It achieves higher accuracy as compared to multi-resolution optical flow registration and other commonly used registration methods. Results of validation show that the lung registration is computed with 3 mm Target Registration Error (TRE) and approximately 3 mm Inverse Consistency Error (ICE). This registration method is further implemented in GPU based real time dose delivery simulation to assist radiation therapy planning.
Show less - Date Issued
- 2012
- Identifier
- CFE0004300, ucf:49464
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004300
- Title
- Purge and Secondary Flow Interaction Control by Means of Platform Circumferential Contouring.
- Creator
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Seco Soley, Melissa, Kapat, Jayanta, Deng, Weiwei, Gordon, Ali, University of Central Florida
- Abstract / Description
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This study presents an attempt to reduce the losses produced by the purge flow in a turbine stage by incorporating circumferential platform contouring. Two contours are proposed and compared against a baseline at different levels of swirl. The computational simulations were performed using a RANS three-dimensional Computational Fluid Dynamics code with the Shear Stress Transport turbulence model. The results of steady simulations demonstrate that for the first contour, when the flow is...
Show moreThis study presents an attempt to reduce the losses produced by the purge flow in a turbine stage by incorporating circumferential platform contouring. Two contours are proposed and compared against a baseline at different levels of swirl. The computational simulations were performed using a RANS three-dimensional Computational Fluid Dynamics code with the Shear Stress Transport turbulence model. The results of steady simulations demonstrate that for the first contour, when the flow is swirled to 50% of the rim speed, the purge flow exits the cavity with less cross flow. This in turn reduces the strength of the passage vortex. However, at swirl extremes of 0% and 100% the baseline has the best performance. The results show that a carefully designed platform has the potential to reduce losses when the operating condition is in the proximity of 50% swirl.
Show less - Date Issued
- 2011
- Identifier
- CFE0004163, ucf:49054
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004163
- Title
- Numerical Study of Interfacial flow using Algebraic Coupled Level Set-Volume of Fluid (A-CLSVOF) Method.
- Creator
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Haghshenas, Majid, Kumar, Ranganathan, Das, Tuhin, Ahmed, Kareem, Shivamoggi, Bhimsen, University of Central Florida
- Abstract / Description
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Solving interfacial flows numerically has been a challenge due to the lack of sharpness and the presence of spurious currents at the interface. Two methods, Algebraic Coupled Level Set-Volume of Fluid (A-CLSVOF) method and Ghost Fluid Method (GFM) have been developed in the finite volume framework and employed in several interfacial flows such as Rayleigh-Taylor instability, rising bubble, impinging droplet and cross-flow oil plume. In the static droplet simulation, A-CLSVOF substantially...
Show moreSolving interfacial flows numerically has been a challenge due to the lack of sharpness and the presence of spurious currents at the interface. Two methods, Algebraic Coupled Level Set-Volume of Fluid (A-CLSVOF) method and Ghost Fluid Method (GFM) have been developed in the finite volume framework and employed in several interfacial flows such as Rayleigh-Taylor instability, rising bubble, impinging droplet and cross-flow oil plume. In the static droplet simulation, A-CLSVOF substantially reduces the spurious currents. The capillary wave relaxation shows that this method delivers results comparable to those of more rigorous methods such as Front Tracking methods for fine grids. The results for the other interfacial flows also compared well with the experimental results. Next, interfacial forces are implemented by enlisting the finite volume discretization of Ghost Fluid Method. To assess the A-CLSVOF/GFM performance, four cases are studied. In the case of the static droplet in suspension, the combined A-CLSVOF/GFM produces a sharp and accurate pressure jump compared to the traditional CSF (continuum surface force) implementation. For the linear two-layer shear flow, GFM sharp treatment of the viscosity captured the velocity gradient across the interface. For a gaseous bubble rising in a viscous fluid, GFM outperforms CSF by almost 10%. Also, a Decoupled Pressure A-CLSVOF/GFM method (DPM) has been developed which separates pressure into two pressure components, one accounting for interfacial forces such as surface tension and another representing the rest of flow pressure. It is proven that the DPM implementation results in more efficiency in PISO (Pressure Implicit with Splitting of Operators) loop. A two-phase solver is used to study buoyant oil discharge in quiescent and cross-flow ambient. Different modes of breakup including dripping, jetting (axisymmetric and asymmetric) and atomization for cross-flow oil jet are captured.
Show less - Date Issued
- 2018
- Identifier
- CFE0007570, ucf:52582
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007570
- Title
- Fluid Flow Characteristics of a Co-Flow Fluidic Slot Jet Thrust Augmentation Propulsion System.
- Creator
-
Garrett, Brian, Ahmed, Kareem, Kapat, Jayanta, Bhattacharya, Samik, University of Central Florida
- Abstract / Description
-
The UAV industry is booming with investments in research and development on improving UAV systems in order to increase applications and reduce costs of the use of these machines. Current UAV machines are developed according to the quadcopter design which has a rotary propulsion system which provides the lift needed for the aerial vehicles. This design has some flaws; namely safety concerns and noise/vibration production both of which come from the rotary propulsion system. As such, a novel...
Show moreThe UAV industry is booming with investments in research and development on improving UAV systems in order to increase applications and reduce costs of the use of these machines. Current UAV machines are developed according to the quadcopter design which has a rotary propulsion system which provides the lift needed for the aerial vehicles. This design has some flaws; namely safety concerns and noise/vibration production both of which come from the rotary propulsion system. As such, a novel propulsion system using slip stream air passed through high performance slot jets is proposed and analysis of the fluid characteristics is presented in this report.The test section for the experiment is developed using 3D printed ABS plastic airfoils modified with internal cavities where pressurized air is introduced and then expelled through slot jets on the pressure side of the airfoils. Entrainment processes develop in the system through high momentum fluid introduction into a sedentary secondary fluid. Entrainment is governed by pressure gradients and turbulent mixing and so turbulent quantities that measure these processes are extracted and analyzed according to the independent variable's effects on these quantities. Pitot probe testing extracted one dimensional fluid information and PIV analysis is used to characterize the two-dimensional flow aspects.High slot jet velocities are seen to develop flows dominated by convection pushing momentum mixing downstream reducing the mixing while low slot jet speeds exhibit higher mass fluxes and thrust development. Confinement spacing is seen to cause a decrease in flow velocity and thrust as the spacing is decreased for high speed runs. The most constricted cross sectional runs showed high momentum mixing and developed combined self-similar flow through higher boundary layer interactions and pressures, but this also hurt thrust development. The Angle of Attack of the assembly proved to be the most important variable. Outward angling showed the influence of coanda effects but also demonstrated the highest bulk fluid flow with turbulence driven momentum mixing. Inward angling created combined fluid flow downstream with high momentum mixing upstream driven by pressure. Minimal mixing is seen when the airfoils are not angled and high recirculation zones along the boundaries. The optimal setup is seen to when the airfoils are angled outwards where the highest thrust and bulk fluid movement is developed driven by the turbulent mixing induced by the increasing cross sectional area of the system.
Show less - Date Issued
- 2019
- Identifier
- CFE0007636, ucf:52509
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007636
- Title
- VARIABLE FLUID FLOW REGIMES ALTER ENDOTHELIAL ADHERENS JUNCTIONS AND TIGHT JUNCTIONS.
- Creator
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Ranadewa, Dilshan, Steward, Robert, Gou, Jihua, Mansy, Hansen, University of Central Florida
- Abstract / Description
-
Variable blood flow regimes influence a range of cellular properties ranging from cell orientation, shape, and permeability: all of which are dependent on endothelial cell-cell junctions. In fact, cell-cell junctions have shown to be an integral part of vascular homeostasis through the endothelium by allowing intercellular signaling and passage control through tight junctions (TJs), adherens junctions (AJs), and gap junctions (GJs). It was our objective to determine the structural response of...
Show moreVariable blood flow regimes influence a range of cellular properties ranging from cell orientation, shape, and permeability: all of which are dependent on endothelial cell-cell junctions. In fact, cell-cell junctions have shown to be an integral part of vascular homeostasis through the endothelium by allowing intercellular signaling and passage control through tight junctions (TJs), adherens junctions (AJs), and gap junctions (GJs). It was our objective to determine the structural response of both AJs and TJs under steady and oscillatory flow. Human brain microvascular endothelial cells (HBMECs) were cultured in a parallel plate flow chamber and exposed to separate trails of steady and oscillatory fluid shear stress for 24 hours. Steady flow regimes consisted of a low laminar flow (LLF) of 1 dyne/cm2, and a high laminar flow (HLF) of 10 dyne/cm2 and oscillatory flow regimes consisted of low oscillatory flow (LOF) +/- 1 dyne/cm2 and high oscillatory flow (HLF) of +/- 10 dyne/cm2. We then imaged the TJs ZO-1 Claudin-5 and AJs JAM-A VE-Cadherin and subsequently analyzed their structural response as a function of pixel intensity. Our findings revealed an increase in pixel intensity between LLF and LOF along the boundary of the cells in both TJs ZO1 Claudin 5. Therefore, our results demonstrate the variable response of different cell-cell junctions under fluid shear, and for the first time, observes the difference in cell-cell junctional structure amongst steady and oscillatory flow regimes
Show less - Date Issued
- 2019
- Identifier
- CFE0007518, ucf:52618
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007518
- Title
- FLOW CONTROL OF TANDEM CYLINDERS USING PLASMA ACTUATORS.
- Creator
-
Larsen, Jonah, Bhattacharya, Samik, University of Central Florida
- Abstract / Description
-
The flow over a set of tandem cylinders at a moderate Reynolds numbers (Re), and with different separation lengths has been studied. Two dimensional (2D) and three-dimensional (3D) plasma actuators were used to control the flow over the leading cylinder to change the vortex shedding, and subsequently the flow on the second cylinder. The 3D plasma actuator was segmented along the length of the cylinder with a spacing of ? = 4 while the 2D actuator simply ran straight down the span of the...
Show moreThe flow over a set of tandem cylinders at a moderate Reynolds numbers (Re), and with different separation lengths has been studied. Two dimensional (2D) and three-dimensional (3D) plasma actuators were used to control the flow over the leading cylinder to change the vortex shedding, and subsequently the flow on the second cylinder. The 3D plasma actuator was segmented along the length of the cylinder with a spacing of ? = 4 while the 2D actuator simply ran straight down the span of the cylinder. Particle image velocimetry (PIV) measurements were used to investigate the flow along the central plane in the wake of the cylinders. The image pairs were processed into velocity grids which were then averaged. Plots of the shear, vorticity, and turbulent kinetic energy were created. These plots are used to understand how the character of vortex shedding from the upstream cylinder changes the same from the downstream one.
Show less - Date Issued
- 2018
- Identifier
- CFH2000425, ucf:45872
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000425
- Title
- Machine Learning Methods for Multiparameter Flow Cytometry Analysis and Visualization.
- Creator
-
Sassano, Emily, Jha, Sumit Kumar, Pattanaik, Sumanta, Hughes, Charles, Moore, Sean, University of Central Florida
- Abstract / Description
-
Flow cytometry is a popular analytical cell-biology instrument that uses specific wavelengths of light to profile heterogeneous populations of cells at the individual level. Current cytometers have the capability of analyzing up to 20 parameters on over a million cells, but despite the complexity of these datasets, a typical workflow relies on subjective labor-intensive manual sequential analysis. The research presented in this dissertation provides two machine learning methods to increase...
Show moreFlow cytometry is a popular analytical cell-biology instrument that uses specific wavelengths of light to profile heterogeneous populations of cells at the individual level. Current cytometers have the capability of analyzing up to 20 parameters on over a million cells, but despite the complexity of these datasets, a typical workflow relies on subjective labor-intensive manual sequential analysis. The research presented in this dissertation provides two machine learning methods to increase the objectivity, efficiency, and discovery in flow cytometry data analysis. The first, a supervised learning method, utilizes previously analyzed data to evaluate new flow cytometry files containing similar parameters. The probability distribution of each dimension in a file is matched to each related dimension of a reference file through color indexing and histogram intersection methods. Once a similar reference file is selected the cell populations previously classified are used to create a tailored support vector machine capable of classifying cell populations as an expert would. This method has produced results highly correlated with manual sequential analysis, providing an efficient alternative for analyzing a large number of samples. The second, a novel unsupervised method, is used to explore and visualize single-cell data in an objective manner. To accomplish this, a hypergraph sampling method was created to preserve rare events within the flow data before divisively clustering the sampled data using singular value decomposition. The unsampled data is added to the discovered set of clusters using a support vector machine classifier, and the final analysis is displayed as a minimum spanning tree. This tree is capable of distinguishing rare subsets of cells comprising of less than 1% of the original data.
Show less - Date Issued
- 2018
- Identifier
- CFE0007243, ucf:52241
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007243
- Title
- "ACETAZOLAMIDE-INDUCED DECREASE OF APICAL FLUID FLOW IN CHOROID PLEXUS IS INDEPENDENT OF THE CONCOMITANT CHANGES IN AQUAPORIN-1 EXPRESSION".
- Creator
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Ameli, Pouya, Chan, Sic, University of Central Florida
- Abstract / Description
-
Acetazolamide (AZA), the only drug approved for treatment of hydrocephalus, is effective in only 25-30% of patients while its effect on fluid flow in the choroid plexus (CP) is unknown. The drug reversibly inhibits Aquaporin 4 (AQP4), the most highly expressed "water pore" in the brain, and it is postulated that it reduces cerebrospinal fluid (CSF) production by modulating AQP1 (mostly found in the apical membrane of the CP). In this study, we sought to elucidate the effect of AZA on AQP1 and...
Show moreAcetazolamide (AZA), the only drug approved for treatment of hydrocephalus, is effective in only 25-30% of patients while its effect on fluid flow in the choroid plexus (CP) is unknown. The drug reversibly inhibits Aquaporin 4 (AQP4), the most highly expressed "water pore" in the brain, and it is postulated that it reduces cerebrospinal fluid (CSF) production by modulating AQP1 (mostly found in the apical membrane of the CP). In this study, we sought to elucidate the effect of AZA on AQP1 and fluid flow in CP. Primary CP culture from p10 Sprague-Dawley rats and TRCSF-B cell line were grown on Transwell permeable supports, treated with 100uM AZA or 100uM Vinpocetine (previously shown to increase AQP1 levels), and tested by: a) Fluid assays using TRITC-labeled Dextran to assay direction and extent of fluid flow; b) Immunoblot, Immunocytochemistry (ICC), and RT-PCR for AQP1 expression. Immnoblots and ICC analyses showed that AQP1 protein levels decrease in a delayed manner (lowest at 12 hours) with AZA treatment. The reduction in AQP1 protein was transient and preceded by a reduction in mRNA levels (lowest at 6 hours). Transwell fluid assays indicate a shift in fluid flow at 2 hours, prior to the changes in AQP1 mRNA or protein. Alteration of fluid flow by AZA (in both primary culture and TR-CSFB) is similar to Vinpocetine's effect in primary culture. Together with drug-induced alterations in AQP1 levels, these data suggest independent mechanisms behind fluid flow and AQP1 expression.
Show less - Date Issued
- 2010
- Identifier
- CFE0003501, ucf:48935
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003501
- Title
- DROPLET FLOWS IN MICROCHANNELS USING LATTICE BOLTZMANN METHOD.
- Creator
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Gupta, Amit, Kumar, Ranganathan, University of Central Florida
- Abstract / Description
-
Microelectromechanical systems (MEMS) have widespread applications in medical, electronical and mechanical devices. These devices are characterized by the smallest dimension which is atleast one micrometer and utmost one millimeter. Rapid progress in the manufacture and utilization of these microdevices has been achieved in the last decade. Current manufacturing techniques of such devices and channels include surface silicon micromachining; bulk silicon micromachining; lithography;...
Show moreMicroelectromechanical systems (MEMS) have widespread applications in medical, electronical and mechanical devices. These devices are characterized by the smallest dimension which is atleast one micrometer and utmost one millimeter. Rapid progress in the manufacture and utilization of these microdevices has been achieved in the last decade. Current manufacturing techniques of such devices and channels include surface silicon micromachining; bulk silicon micromachining; lithography; electrodeposition and plastic molding; and electrodischarge machining (EDM). In recent years, electrostatic, magnetic, electromagnetic and thermal actuators, valves, gears and diaphragms of dimensions of hundred microns or less have been fabricated successfully. Sensors have been manufactured that can detect pressure, temperature, flow rate and chemical composition in such channels. Physical effects such as electrokinetics, pressure gradient and capillarity become prominent for channels where the length scales are of the order of hundreds of micrometers. Also, at such length scales, the application of conventional numerical techniques that use macroscale equations to describe the phenomenon is questionable as the validity of the no-slip boundary condition depends on the ratio of the mean free path of the fluid molecules to the characteristic dimension of the problem (called the Knudsen number). Macroscale equations can only be applied if Knudsen number is of the order of 10¬¬-3 or less. In recent years, the lattice Boltzmann method (LBM) has emerged as a powerful tool that has replaced conventional macroscopic techniques like Computational Fluid Dynamics (CFD) in many applications involving complex fluid flow. The LBM starts from meso- and microscopic Boltzmann's kinetic equation and can be used to determine macroscopic fluid dynamics. The origins of LBM can be drawn back to lattice gas cellular automata (LGCA) which lacked Galilean invariance and created statistical noise in the system. LBM on the other hand possesses none of these drawbacks of LGCA, and is easy to implement in complex geometries and can be used to study detailed microscopic flow behavior in complex fluids/fluid mixtures. Nor does it have any of the drawbacks of the Navier-Stokes solvers of implementing the slip boundary condition on the surface of a solid. It has also been found to be computationally fast and an alternative to Navier-Stokes equations. In this study, LBM is used to simulate two-fluid flows such as bubbles rising in a liquid, droplet impingement on a dry surface and creation of emulsions in microchannels. Simulation of disperse flows in a continuous medium using simple boundary condition methods lays the foundation of conducting complex simulations for the formation of droplets past a T-junction microchannel in the framework of this statistical method. Simulations in a T-junction illustrate the effect of the channel geometry, the viscosity of the liquids and the flow rates on the mechanism, volume and frequency of formation of these micron-sized droplets. Based on the interplay of viscous and surface tension forces, different shapes and sizes of droplets were found to form. The range of Capillary numbers simulated lies between 0.001Show less - Date Issued
- 2009
- Identifier
- CFE0002618, ucf:48279
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002618
- Title
- A Computer Graphics Analysis of a Freeway Merge Control System.
- Creator
-
Risher, Thomas A., Bauer, Christian, Engineering
- Abstract / Description
-
Florida Technological University College of Engineering Thesis; In 1975, C.S. Bauer completed a doctoral dissertation at the University of Florida which treated the Green Band Merging Control System on I-75 in Tampa, Florida. In this work, Bauer suggested the possibility for the use of computer graphics as a toll for analysis of the bands generated by the Green Band Control System Simulation developed in his dissertation. The use of computer generated movies of the bands displayed to ramp...
Show moreFlorida Technological University College of Engineering Thesis; In 1975, C.S. Bauer completed a doctoral dissertation at the University of Florida which treated the Green Band Merging Control System on I-75 in Tampa, Florida. In this work, Bauer suggested the possibility for the use of computer graphics as a toll for analysis of the bands generated by the Green Band Control System Simulation developed in his dissertation. The use of computer generated movies of the bands displayed to ramp drivers by the system allows the comparison of various band control strategies without the need for field implementation and testing. With the goal of producing such films in mind, the research topic discussed in this paper was undertaken. The report introduces the reader to some of the basic aspects of computer graphics and presents specialized computer software and interface hardware for producing automated computer graphics movies from a Tektronix 4010 storage display. A brief discussion of the Tampa System and its associated simulation program is presented, and representative frames from the moves of the Tampa System produced in the research are discussed. Suggestions for additional work that could be undertaken in the research area conclude the report.
Show less - Date Issued
- 1976
- Identifier
- CFR0011597, ucf:53042
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFR0011597
- Title
- The subjective gameplay experience: An examination of the revised game engagement model.
- Creator
-
Procci, Katelyn, Bowers, Clint, Jentsch, Florian, Sims, Valerie, McDaniel, Rudy, University of Central Florida
- Abstract / Description
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The study of the subjective gameplay experience spans multiple disciplines, from teachers who want to harness the power of gameplay to enhance instruction to game developers hoping to create the next big hit. Despite decades of interest, little agreement has been found regarding the way constructs(-)such as immersion, involvement, presence, and flow(-)are used to describe the subjective gameplay experience. Without the consistent usage of well-defined constructs, it becomes impossible to...
Show moreThe study of the subjective gameplay experience spans multiple disciplines, from teachers who want to harness the power of gameplay to enhance instruction to game developers hoping to create the next big hit. Despite decades of interest, little agreement has been found regarding the way constructs(-)such as immersion, involvement, presence, and flow(-)are used to describe the subjective gameplay experience. Without the consistent usage of well-defined constructs, it becomes impossible to further scientific understanding of this domain. This dissertation examined the theoretical evolution of the key subjective gameplay experience constructs. From this, definitions for immersion, involvement, presence, and flow were extracted. Based on the prior work of Brockmyer et al. (2009), a revised game engagement model was created that incorporated these definitions. To test the proposed relationships within the revised game engagement model, experienced players of the computer game Minecraft were recruited for an experimental study. The participants played the game Minecraft, which was manipulated with respect to both level of difficulty and immersive aspects. This allowed for a range of potential game engagement states to be experienced by the participants. Several individual differences hypothesized to influence the different constructs of game engagement also were measured. The results of the study supported many proposed aspects of the revised game engagement model and revealed ways in which the model could be further refined. The theoretically-derived definitions and revised game engagement model resulting from this work, along with the suggested measures for these relevant constructs, provides a framework for future work in this area. This framework will improve the consistency of construct operationalization, benefiting the continued study of the subjective gameplay experience.
Show less - Date Issued
- 2015
- Identifier
- CFE0005691, ucf:50128
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005691
- Title
- Response of Electrified Micro-Jets to Electrohydrodynamic Perturbations.
- Creator
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Yang, Weiwei, Deng, Weiwei, Chen, Ruey-Hung, Ilie, Marcel, University of Central Florida
- Abstract / Description
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The breakup of liquid jets is ubiquitous with rich underpinning physics and widespread applications. The natural breakup of liquid jets originates from small ambient perturbations, which can grow exponentially until the amplitude as large as the jet radius is reached. For unelectrified inviscid jets, surface energy analysis shows that only the axisymmetric perturbation is possibly unstable, and this mode is referred as varicose instability. For electrified jets, the presence of surface charge...
Show moreThe breakup of liquid jets is ubiquitous with rich underpinning physics and widespread applications. The natural breakup of liquid jets originates from small ambient perturbations, which can grow exponentially until the amplitude as large as the jet radius is reached. For unelectrified inviscid jets, surface energy analysis shows that only the axisymmetric perturbation is possibly unstable, and this mode is referred as varicose instability. For electrified jets, the presence of surface charge enables additional unstable modes, among which the most common one is the whipping (or kink) instability that bends and stretches the charged jet that is responsible for the phenomena of electrospinning. A closer examination of the two instabilities suggests that due to mass conservation, the uneven jet stretching from whipping may translate into radial perturbations and trigger varicose instabilities. Although the varicose and whipping instabilities of electrified micro-jets have both been extensively studied separately, there is little attention paid to the combined effect of these two, which may lead to new jet breakup phenomena. This dissertation investigates the dynamic response of electrified jets under transverse electrohydrodynamic (EHD) perturbations which were introduced by exciters driven by alternating voltage of sweeping frequency. Three different jetting mechanisms are used to generate jets with various ranges of jet diameters: ~150 micrometer inertial jets from liquid pressurized through a small orifice, ~50 micrometer flow focused jets, and ~20 micrometer electrified Taylor-cone jets. The transverse perturbations enable systematic triggering of varicose and whipping instabilities, and consequently a wide range of remarkable phenomena emerge. For inertial jets with zero or low charge levels, only varicose instability is observable due to suppressed whipping instability. At modest charge levels, inertia jets can respond to the fundamental perturbation frequency as well as the second harmonic of the perturbation frequency. Highly charged jets such as fine jets generated from Taylor cones exhibit distinct behavior for different perturbation wavenumber x. Typical behavior include: whipping jets with superimposed varicose instability at small x, jet bifurcation from crossover of whipping and varicose instabilities at x~0.5, Coulombic fission owing to the surge of surface charge density as the slender liquid segments recover spherical shapes at x~0.7, and simple varicose mode near wave numbers of unity. The phenomena observed in this work may be explained by a linear model and rationalized by the phase diagram in the space of wave number and dimensionless charge levels. The experimental apparatus used in this dissertation is simple, non-intrusive, and scalable to a linear array of jets. The rich phenomena combined with the versatile apparatus may spawn new research directions such as regulated electrospinning, generating strictly monodisperse micro/nano droplets, and manufacturing of non-spherical particles from drying droplets that undergo controlled Coulombic fissions.
Show less - Date Issued
- 2014
- Identifier
- CFE0005744, ucf:50086
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005744
- Title
- MODELING LANE-BASED TRAFFIC FLOW IN EMERGENCY SITUATIONS IN THE PRESENCE OF MULTIPLE HETEROGENEOUS FLOWS.
- Creator
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Saleh, Amani, Geiger, Christopher, University of Central Florida
- Abstract / Description
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In recent years, natural, man-made and technological disasters have been increasing in magnitude and frequency of occurrence. Terrorist attacks have increased after the September 11, 2001. Some authorities suggest that global warming is partly the blame for the increase in frequency of natural disasters, such as the series of hurricanes in the early-2000's. Furthermore, there has been noticeable growth in population within many metropolitan areas not only in the US but also worldwide....
Show moreIn recent years, natural, man-made and technological disasters have been increasing in magnitude and frequency of occurrence. Terrorist attacks have increased after the September 11, 2001. Some authorities suggest that global warming is partly the blame for the increase in frequency of natural disasters, such as the series of hurricanes in the early-2000's. Furthermore, there has been noticeable growth in population within many metropolitan areas not only in the US but also worldwide. 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. This research considers aspects of evacuation routing never before considered 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 unanticipated emergencies. By incompatible, it is meant that the two different flows cannot occupy a given lane and merge or crossing point in the travel network at the same time. In addition, in large-scale evacuations, travel lane normal flow directions can be reversed dynamically to their contraflow directions depending upon the degree of the emergency. These characteristics provide the basis for this investigation. This research considers the multiple flow EERP problem where the network travel lanes can be reconfigured using contraflow lane reversals. The first flow is vehicular flow of evacuees from the source of a hazard to destinations of safety, and the second flow is the emergency first responders to the hazard source. After presenting a review of the work related to the multiple flow EERP problem, mathematical formulations are proposed for three variations of the EERP problem where the objective for each problem is to identify an evacuation plan (i.e., a flow schedule and network contraflow lane configuration) that minimizes network clearance time. Before the proposed formulations, the evacuation problem that considers only the flow of evacuees out of the network, which is viewed as a maximum flow problem, is formulated as an integer linear program. Then, the first proposed model formulation, which addresses the problem that considers the flow of evacuees under contraflow conditions, is presented. Next, the proposed formulation is expanded to consider the flow of evacuees and responders through the network but under normal flow conditions. Lastly, the two-flow problem of evacuees and responders under contraflow conditions is formulated. Using real-world population and travel network data, the EERP problems are each solved to optimality; however, the time required to solve the problems increases exponentially as the problem grows in size and complexity. Due to the intractable nature of the problems as the size of the network increases, a genetic-based heuristic solution procedure that generates evacuation network configurations of reasonable quality is proposed. The proposed heuristic solution approach generates evacuation plans in the order of minutes, which is desirable in emergency situations and needed to allow for immediate evacuation routing plan dissemination and implementation in the targeted areas.
Show less - Date Issued
- 2008
- Identifier
- CFE0002168, ucf:47512
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002168
- Title
- DEVELOPMENT OF OPTICAL COHERENCE TOMOGRAPHY FOR TISSUE DIAGNOSTICS.
- Creator
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Meemon, Panomsak, Rolland, Jannick, University of Central Florida
- Abstract / Description
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Microvasculature can be found in almost every part of the human body, including the internal organs. Importantly, abnormal changes in microvasculature are usually related to pathological development of the tissue cells. Monitoring of changes in blood flow properties in microvasculature, therefore, provides useful diagnostic information about pathological conditions in biological tissues as exemplified in glaucoma, diabetes, age related macular degeneration, port wine stains, burn-depth, and...
Show moreMicrovasculature can be found in almost every part of the human body, including the internal organs. Importantly, abnormal changes in microvasculature are usually related to pathological development of the tissue cells. Monitoring of changes in blood flow properties in microvasculature, therefore, provides useful diagnostic information about pathological conditions in biological tissues as exemplified in glaucoma, diabetes, age related macular degeneration, port wine stains, burn-depth, and potentially skin cancer. However, the capillary network is typically only one cell in wall thickness with 5 to 10 microns in diameter and located in the dermis region of skin. Therefore, a non-invasive flow imaging technique that is capable of depth sectioning at high resolution and high speed is demanded. Optical coherence tomography (OCT), particularly after its advancement in frequency domain OCT (FD-OCT), is a promising tool for non-invasive high speed, high resolution, and high sensitivity depth-resolved imaging of biological tissues. Over the last ten years, numerous efforts have been paid to develop OCT-based flow imaging techniques. An important effort is the development of phase-resolved Doppler OCT (PR-DOCT). Phase-resolved Doppler imaging using FD-OCT is particularly of interest because of the direct access to the phase information of the depth profile signal. Furthermore, the high speed capability of FD-OCT is promising for real time flow monitoring as well as 3D flow segmentation applications. However, several challenges need to be addressed; 1) Flow in biological samples exhibits a wide dynamic range of flow velocity caused by, for example, the variation in the flow angles, flow diameters, and functionalities. However, the improvement in imaging speed of FD-OCT comes at the expense of a reduction in sensitivity to slow flow information and hence a reduction in detectable velocity range; 2) A structural ambiguity so-called 'mirror image' in FD-OCT prohibits the use of maximum sensitivity and imaging depth range; 3) The requirement of high lateral resolution to resolve capillary vessels requires the use of an imaging optics with high numerical aperture (NA) that leads to a reduction in depth of focus (DOF) and hence the imaging depth range (i.e. less than 100 microns) unless dynamic focusing is performed. Nevertheless, intrinsic to the mechanism of FD-OCT, dynamic focusing is not possible. In this dissertation, the implementation of PR-DOCT in a high speed swept-source based FD-OCT is investigated and optimized. An acquisition scheme as well as a processing algorithm that effectively extends the detectable velocity dynamic range of the PR-DOCT is presented. The proposed technique increased the overall detectable velocity dynamic range of PR-DOCT by about five times of that achieved by the conventional method. Furthermore, a novel technique of mirror image removal called ÃÂ'Dual-Detection FD-OCTÃÂ' (DD-FD-OCT) is presented. One of the advantages of DD-FD-OCT to Doppler imaging is that the full-range signal is achieved without manipulation of the phase relation between consecutive axial lines. Hence the full-range DD-FD-OCT is fully applicable to phase-resolved Doppler detection without a reduction in detectable velocity dynamic range as normally encountered in other full-range techniques. In addition, PR- DOCT can utilize the maximum signal-to-noise ratio provided by the full-range capability. This capability is particularly useful for imaging of blood flow that locates deep below the sample surface, such as blood flow at deep posterior human eye and blood vessels network in the dermis region of human skin. Beside high speed and functional imaging capability, another key parameter that will open path for optical diagnostics using OCT technology is high resolution imaging (i.e. in a regime of a few microns or sub-micron). Even though the lateral resolution of OCT can be independently improved by opening the NA of the imaging optics, the high lateral resolution is maintained only over a short range as limited by the depth of focus that varies inversely and quadratically with NA. Recently developed by our group, ÃÂ'Gabor-Domain Optical Coherence MicroscopyÃÂ' (GD-OCM) is a novel imaging technique capable for invariant resolution of about 2-3 microns over a 2 mm cubic field-of-view. This dissertation details the imaging protocol as well as the automatic data fusion method of GD-OCM developed to render an in-focus high-resolution image throughout the imaging depth of the sample in real time. For the application of absolute flow measurement as an example, the precise information about flow angle is required. GD-OCM provides more precise interpretation of the tissue structures over a large field-of-view, which is necessary for accurate mapping of the flow structure and hence is promising for diagnostic applications particularly when combined with Doppler imaging. Potentially, the ability to perform high resolution OCT imaging inside the human body is useful for many diagnostic applications, such as providing an accurate map for biopsy, guiding surgical and other treatments, monitoring the functional state and/or the post-operative recovery process of internal organs, plaque detection in arteries, and early detection of cancers in the gastrointestinal tract. Endoscopic OCT utilizes a special miniature probe in the sample arm to access tubular organs inside the human body, such as the cardiovascular system, the lung, the gastrointestinal tract, the urinary tract, and the breast duct. We present an optical design of a dynamic focus endoscopic probe that is capable of about 4 to 6 microns lateral resolution over a large working distance (i.e. up to 5 mm from the distal end of the probe). The dynamic focus capability allows integration of the endoscopic probe to GD-OCM imaging to achieve high resolution endoscopic tomograms. We envision the future of this developing technology as a solution to high resolution, minimally invasive, depth-resolved imaging of not only structure but also the microvasculature of in vivo biological tissues that will be useful for many clinical applications, such as dermatology, ophthalmology, endoscopy, and cardiology. The technology is also useful for animal study applications, such as the monitoring of an embryoÃÂ's heart for the development of animal models and monitoring of changes in blood circulation in response to external stimulus in small animal brains.
Show less - Date Issued
- 2010
- Identifier
- CFE0003442, ucf:48392
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003442
- Title
- MEASUREMENTS IN AIR-WATER BUBBLY FLOW THROUGH A VERTICAL NARROW HIGH-ASPECT RATIO CHANNEL.
- Creator
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Patrick, Benjamin, Kumar, Ranganathan, University of Central Florida
- Abstract / Description
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Two-Phase bubbly flows are encountered in a wide range of industrial applications, particularly where phase changes occur as seen in high performance heat exchangers and boiling reactors for power generation. These flows have been extensively studied in channels with circular geometries using air-water flows, though little data exists for flows through narrow rectangular channels. Measurements in thin geometries are particularly challenging since large bubbles bridge the gap, and it is...
Show moreTwo-Phase bubbly flows are encountered in a wide range of industrial applications, particularly where phase changes occur as seen in high performance heat exchangers and boiling reactors for power generation. These flows have been extensively studied in channels with circular geometries using air-water flows, though little data exists for flows through narrow rectangular channels. Measurements in thin geometries are particularly challenging since large bubbles bridge the gap, and it is difficult to compare point measurements with photographic techniques. The objective of this study is to explore the abilities of hot-film anemometry and high speed photography for taking measurements in a narrow vertical rectangular channel for a range of volume fractions, with particular attention on the narrow dimension. Hot-film anemometry (HFA) is a measurement technique originally developed for the measurement of fluid velocities, but has since been found to have applications for broader measurements in multiphase flow. With the sensor operating on the principle of heat loss, the method takes advantage of the differing abilities of the phases to transport heat, with each phase leaving its own signature in the signal response. The linchpin of this method lies in the ability to accurately distinguish between the two phases within the signal, and to execute this operation, various algorithms and techniques have been developed and used with some success for a wide range of flow conditions. This thesis is a study of the various methods of analysis such as amplitude threshold for triggering, and small slope threshold for finely tuning the edges of the bubble interactions, and demonstrates the capabilities of the hot-film sensor in a narrow rectangular vertical duct with a high aspect ratio. A vertical acrylic test section was fabricated for the purposes of this study, inset with a rectangular channel 38.1mm in width and 3.125mm in depth. Experiments were conducted for volume fractions ranging from 2% to 35%, which remained within the limits of the bubbly flow regime, but ranged from small uniform bubbles to larger bubbles coalescing into a transition regime. The hot-film signal was analyzed for void fraction, bubble speed, and bubble size. An in- depth study of the various methods of phase discrimination was performed and the effect of threshold selection was examined. High-speed video footage was taken in conjunction with the anemometer data for a detailed comparison between methods. The bubble speed was found to be in close agreement between the HFA and high-speed video, staying within 10% for volume fractions above 10%, but still remaining under a 30% difference for even as low as the 2% volume fraction, where measurements have been found to be historically difficult. The trends with volume fraction between the HFA and high-speed results were very similar. A correlation for narrow rectangular channels employing a simple drift flux model was found to compare with the void fraction data where appropriate. Good agreement was found between the methods using a hybrid phase discrimination technique for the HFA data for the void fraction and bubble speed results, with the high-speed video results showing a slight over-estimation in regards to the bubble size.
Show less - Date Issued
- 2011
- Identifier
- CFE0004006, ucf:49185
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004006
- Title
- HYBRID AND HIERARCHICAL IMAGE REGISTRATION TECHNIQUES.
- Creator
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Xu, Dongjiang, Kasparis, Takis, University of Central Florida
- Abstract / Description
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A large number of image registration techniques have been developed for various types of sensors and applications, with the aim to improve the accuracy, computational complexity, generality, and robustness. They can be broadly classified into two categories: intensity-based and feature-based methods. The primary drawback of the intensity-based approaches is that it may fail unless the two images are misaligned by a moderate difference in scale, rotation, and translation. In addition,...
Show moreA large number of image registration techniques have been developed for various types of sensors and applications, with the aim to improve the accuracy, computational complexity, generality, and robustness. They can be broadly classified into two categories: intensity-based and feature-based methods. The primary drawback of the intensity-based approaches is that it may fail unless the two images are misaligned by a moderate difference in scale, rotation, and translation. In addition, intensity-based methods lack the robustness in the presence of non-spatial distortions due to different imaging conditions between images. In this dissertation, the image registration is formulated as a two-stage hybrid approach combining both an initial matching and a final matching in a coarse-to-fine manner. In the proposed hybrid framework, the initial matching algorithm is applied at the coarsest scale of images, where the approximate transformation parameters could be first estimated. Subsequently, the robust gradient-based estimation algorithm is incorporated into the proposed hybrid approach using a multi-resolution scheme. Several novel and effective initial matching algorithms have been proposed for the first stage. The variations of the intensity characteristics between images may be large and non-uniform because of non-spatial distortions. Therefore, in order to effectively incorporate the gradient-based robust estimation into our proposed framework, one of the fundamental questions should be addressed: what is a good image representation to work with using gradient-based robust estimation under non-spatial distortions. With the initial matching algorithms applied at the highest level of decomposition, the proposed hybrid approach exhibits superior range of convergence. The gradient-based algorithms in the second stage yield a robust solution that precisely registers images with sub-pixel accuracy. A hierarchical iterative searching further enhances the convergence range and rate. The simulation results demonstrated that the proposed techniques provide significant benefits to the performance of image registration.
Show less - Date Issued
- 2004
- Identifier
- CFE0000317, ucf:46294
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000317