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Title: Elementary quantum mechanics.
Creator: Saxon, David S.
Abstract/Description: This book is based on lectures given by the author in an intensive undergraduate course in quantum mechanics which occupies a central role in the physics curriculum at UCLA. It is a required course for all third-year physics and astrophysics students, but it is taken by some seniors and many graduate students, both in physics and in related fields. Elementary Quantum Mechanics is part of the Florida Atlantic University Libraries Digital Collection and was contributed to the FAU repository by...
Show moreThis book is based on lectures given by the author in an intensive undergraduate course in quantum mechanics which occupies a central role in the physics curriculum at UCLA. It is a required course for all third-year physics and astrophysics students, but it is taken by some seniors and many graduate students, both in physics and in related fields. Elementary Quantum Mechanics is part of the Florida Atlantic University Libraries Digital Collection and was contributed to the FAU repository by the Department of Physics.
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Date Issued: 1968
PURL: http://purl.flvc.org/fau/fd/FA00003911
Format: Document (PDF)

Title: 2012-2013 Program Review Physics.
Creator: Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2012-2013
PURL: http://purl.flvc.org/fau/fd/FA00007691
Format: Document (PDF)

Title: 2010-2011 Program Review Physics.
Creator: Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2010-2011
PURL: http://purl.flvc.org/fau/fd/FA00007684
Format: Document (PDF)

Title: 2014-2015 Program Review Physics.
Creator: Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2014-2015
PURL: http://purl.flvc.org/fau/fd/FA00007705
Format: Document (PDF)

Title: 2016-2017 Program Review Physics.
Creator: Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2016-2017
PURL: http://purl.flvc.org/fau/fd/FA00007719
Format: Document (PDF)

Title: 2009-2010 Program Review Physics.
Creator: Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2009-2010
PURL: http://purl.flvc.org/fau/fd/FA00007677
Format: Document (PDF)

Title: 2015-2016 Program Review Physics.
Creator: Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2015-2016
PURL: http://purl.flvc.org/fau/fd/FA00007712
Format: Document (PDF)

Title: 2013-2014 Program Review Physics.
Creator: Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2013-2014
PURL: http://purl.flvc.org/fau/fd/FA00007698
Format: Document (PDF)

Title: Anisotropic physical properties of SC-15 epoxy reinforced with magnetic nanofillers under uniform magnetic field.
Creator: Malkina, Olga, Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: SC-15 epoxy is used in many industrial applications and it is well known that the mechanical and viscoelastic properties of epoxy can be signicantly enhanced when reinforced with nanofillers. In this work, SC-15 epoxy is reinforced by loading with magnetically-active nanofillers and cured in a modest magnetic field. Because of the signicant magnetic response of the nanofillers, this is a low cost and relatively easy technique for imposing a strong magnetic anisotropy to the system without the...
Show moreSC-15 epoxy is used in many industrial applications and it is well known that the mechanical and viscoelastic properties of epoxy can be signicantly enhanced when reinforced with nanofillers. In this work, SC-15 epoxy is reinforced by loading with magnetically-active nanofillers and cured in a modest magnetic field. Because of the signicant magnetic response of the nanofillers, this is a low cost and relatively easy technique for imposing a strong magnetic anisotropy to the system without the need of a superconducting magnet. It is also found that this method is an effective way of enhancing the mechanical properties of epoxy. Three systems were prepared and studied. The first is a dilute system of various concentrations of Fe2O3 nanoparticles in SC-15 epoxy. The second system is a combination of Fe2O3 nanoparticles and chemically-functionalized single-walled carbon nanotubes (SWCNT(COOH)s) in SC-15 epoxy. The third is a dilute system of SWCNT(COOH)s decorated with Fe3O4 particles t hrough a sonochemical oxidation process in SC-15 epoxy. Samples have an initial cure of 6 hrs in a magnetic led of 10 kOe followed by an additional 24 hours of post curing at room temperature. These are compared to the control samples that do not have initial field curing. Tensile and compressive stress-strain analysis of the prepared systems shows that mechanical properties such as tensile strength, tensile modulus and compressive strength are enhanced with the inclusion of these nanofillers. It is also found that there is an anisotropic enhancement of these properties with respect to the imposed curing field. An interesting phenomenon is observed with the increase in modulus of toughness and fracture strain with nanotube inclusion., These parameters are drastically enhanced after curing the systems in a magnetic field. While there is a modest shift in glass transition temperature during viscoelastic analysis, the thermal stability of the created systems is not compromised. Results of these mechanical enhancements will be compared with other nanoloading techniques from literature.
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Date Issued: 2011
PURL: http://purl.flvc.org/FAU/3332722
Subject Headings: Nanostructured materials, Epoxy resins, Composite materials, Design
Format: Document (PDF)

Title: Binary black hole mergers: alternatives to standard puncture initial data and the impact on gravitational waveforms.
Creator: Reifenberger, George C., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: We study the evolution of binary black hole initial data schemes as alternatives to the standard puncture construction. These alternatives are based on post-Newtonian expansions that contain realistic gravitational waves. The first scheme is based on a second order post-Newtonian expansion in Arnowitt, Deser, and Misner transverse-traceless (ADMTT) gauge that has been re-summed to approach standard puncture data at the black holes. The other schemes are based on asymptotic matching of the 4...
Show moreWe study the evolution of binary black hole initial data schemes as alternatives to the standard puncture construction. These alternatives are based on post-Newtonian expansions that contain realistic gravitational waves. The first scheme is based on a second order post-Newtonian expansion in Arnowitt, Deser, and Misner transverse-traceless (ADMTT) gauge that has been re-summed to approach standard puncture data at the black holes. The other schemes are based on asymptotic matching of the 4-metrics of two tidally perturbed Schwarzschild solutions to post-Newtonian expansions at different orders. The alternatives are encouraging and lead to quasi-circular orbits and show gravitational radiation from the onset, as well as a reduction of spurious radiation. Deficiencies compared to punctures include more eccentricity during inspiral and larger constraint violations, since the alternative data sets only approximate solutions of Einstein's equations.
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Date Issued: 2013
PURL: http://purl.flvc.org/fcla/dt/3362577
Subject Headings: Black holes (Astronomy), General relativity (Physics), Gravitational waves, Inertia (Mechanics), Mass (Physics), Particles (Nuclear physics)
Format: Document (PDF)

Title: Biogenic gas dynamics in peat soil blocks using ground penetrating radar: a comparative study in the laboratory between peat soils from the Everglades and from two northern peatlands in Minnesota and Maine.
Creator: Cabolova, Anastasija., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: Peatlands cover a total area of approximately 3 million square kilometers and are one of the largest natural sources of atmospheric methane (CH4) and carbon dioxide (CO2). Most traditional methods used to estimate biogenic gas dynamics are invasive and provide little or no information about lateral distribution of gas. In contrast, Ground Penetrating Radar (GPR) is an emerging technique for non-invasive investigation of gas dynamics in peat soils. This thesis establishes a direct comparison...
Show morePeatlands cover a total area of approximately 3 million square kilometers and are one of the largest natural sources of atmospheric methane (CH4) and carbon dioxide (CO2). Most traditional methods used to estimate biogenic gas dynamics are invasive and provide little or no information about lateral distribution of gas. In contrast, Ground Penetrating Radar (GPR) is an emerging technique for non-invasive investigation of gas dynamics in peat soils. This thesis establishes a direct comparison between gas dynamics (i.e. build-up and release) of four different types of peat soil using GPR. Peat soil blocks were collected at peatlands with contrasting latitudes, including the Everglades, Maine and Minnesota. A unique two-antenna GPR setup was used to monitor biogenic gas buildup and ebullition events over a period of 4.5 months, constraining GPR data with surface deformation measurements and direct CH4 and CO2 concentration measurements. The effect of atmospheric pressure was also investigated. This study has implications for better understanding global gas dynamics and carbon cycling in peat soils and its role in climate change.
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Date Issued: 2010
PURL: http://purl.flvc.org/FAU/2974433
Subject Headings: Wetland ecology, Wetland ecology, Wetland ecology, Gas dynamics, Soil permeability, Ground penetrating radar, Porous materials, Fluid dynamics
Format: Document (PDF)

Title: Diffusion tensor imaging in mild traumatic brain injuries.
Creator: Hotiu, Angelica, Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: Mild traumatic brain injuries (MTBI) are the leading type of head injuries with appreciable risque of sequelae leading to functional and psychological deficits. Although mild traumatic brain injuries are frequently underdiagnosed by conventional imaging modalities, rapidly evolving techniques such as diffusion tensor imaging (DTI) reveal subtle changes in white matter integrity as a result of head trauma and play an important role in refining diagnosis, therapeutic interventions and...
Show moreMild traumatic brain injuries (MTBI) are the leading type of head injuries with appreciable risque of sequelae leading to functional and psychological deficits. Although mild traumatic brain injuries are frequently underdiagnosed by conventional imaging modalities, rapidly evolving techniques such as diffusion tensor imaging (DTI) reveal subtle changes in white matter integrity as a result of head trauma and play an important role in refining diagnosis, therapeutic interventions and management of MTBI. In this dissertation we use diffusion tensor imaging to detect the microstructural changes induced by axonal injuries and to monitor their evolution during the recovery process. DTI data were previously acquired from 11 subjects, football players of age 19-23 years (median age 20 years). Three players had suffered a mild traumatic brain injury during the season and underwent scanning within 24 hours after the injury with follow-ups after one and two weeks. A set of diffusion indices, such as fractional anisotropy, axial, radial and mean diffusivity were derived from the diffusion tensor. Changes in diffusion indices in concussed subjects were analyzed based on two different approaches: whole brain analysis, using tract-based spatial statistics (TBSS) and region of interest analysis (ROI). In both approaches we use a voxelwise analysis to examine group differences in diffusion indices between five controls and three concussed subjects for all DTI scans. Additional statistical analysis was performed between control groups consisting of five and three non-injured players. Both analyses demonstrated that the MTBI group reveals increase in fractional anisotropy and decreases in transversal and mean diffusivity in cortical and subcortical areas within 24 hours after the injury., No changes were detected in TBSS analysis for the follow-up data sets. Furthermore, our ROI approach revealed multiples regions with significantly different voxels, non-uniformly distributed throughout the brain, for all diffusion indices in all three scans. Three of the diffusion indices fractional anisotropy, mean and transversal diffusivity showed higher vulnerability to head trauma in subcortical and cortical areas than in regions in the lower brain. Recovery of white matter pathways occured at different locations in the brain at one and two weeks after head trauma. Strong recovery was observed in mean and transversal diffusivity in subcortical areas that correspond to the corticospinal tract. No recovery was found for fractional anisotropy and axial diffusivity in the same region. Also, decreases in fractional anisotropy and increases in transversal and axial diffusivity were observed in the spleninum of the corpus callosum. As voxelwise analysis performed on DTI data revealed white matter regions, which exhibit changes in diffusion parameters in the concussed group for all three scans, we conclude that diffusion tensor imaging is a powerful technique for early detection of axonal injuries and may serve as an important tool for monitoring microstructural changes during the recovery process.
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Date Issued: 2010
PURL: http://purl.flvc.org/FAU/2100579
Subject Headings: Brain, Magnetic resonance imaging, Brain, Concussion, Diagnosis, Neuropsychology, Diffusion tensor imaging
Format: Document (PDF)

Title: Evaluation of surface dose outside the treatment area for breast cancer irradiation modalities using thermoluminescence dosimeters (TLDs).
Creator: Khanal, Suraj P., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: The purpose of this research is to compare the surface dose outside the treatment area for different breast cancer irradiation modalities using Thermoluminescence Dosimeters (TLDs). Five different modalities are included in this study: Accuboost, Photon boost, Electron boost, Strut-Adjusted Volume Implant (SAVI), and Mammosite Multi-lumen (ML).Six points of interest (POI) on the breast cancer patients had been selected for the TLDs placement. Data from 25 breast cancer patients at Lynn Cancer...
Show moreThe purpose of this research is to compare the surface dose outside the treatment area for different breast cancer irradiation modalities using Thermoluminescence Dosimeters (TLDs). Five different modalities are included in this study: Accuboost, Photon boost, Electron boost, Strut-Adjusted Volume Implant (SAVI), and Mammosite Multi-lumen (ML).Six points of interest (POI) on the breast cancer patients had been selected for the TLDs placement. Data from 25 breast cancer patients at Lynn Cancer Institute of the Boca Raton Regional Hospital were included in the study. The measured percentage ranges of the averaged doses at the six POIs for the different modalities are: Sternum 0.26% - 3.26%, Shoulder 0.33% - 2.79%, Eye 0.26% - 1.32%, Thyroid 0.20% - 2.75%, CLB 0.2% - 5.46%, Lower Abdomen 0.16% - 2.25%.
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Date Issued: 2013
PURL: http://purl.flvc.org/fcla/dt/3362479
Subject Headings: Thermoluminescence, Therapeutic use, Radiation dosimetry, Breast, Cancer, Treatmernt, Radiation, Measurement, Methodology
Format: Document (PDF)

Title: Detecting the spatiotemporal dynamics of neural activity on the cortical surface: applying anatomically constrained beamforming to EEG.
Creator: Murzin, Vyacheslav., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: The neurophysiological signals that are recorded in EEG (electroencephalography) and MEG (magnetoencephalography) originate from current flow perpendicular to the cortical surface due to the columnar organization of pyramidal cells in the cortical gray matter. These locations and directions have been used as anatomical constraints for dipolar sources in estimations of neural activity from MEG recordings. Here we extend anatomically constrained beamforming to EEG, which requires a more...
Show moreThe neurophysiological signals that are recorded in EEG (electroencephalography) and MEG (magnetoencephalography) originate from current flow perpendicular to the cortical surface due to the columnar organization of pyramidal cells in the cortical gray matter. These locations and directions have been used as anatomical constraints for dipolar sources in estimations of neural activity from MEG recordings. Here we extend anatomically constrained beamforming to EEG, which requires a more sophisticated forward model than MEG due to the blurring of the electric potential at tissue boundaries, but in contrast to MEG, EEG can account for both tangential and radial sources. Using computed tomography (CT) scans we create a realistic three-layer head model consisting of tessellated surfaces representing the tissue boundaries cerebrospinal fluid-skull, skull-scalp and scalp-air. The cortical gray matter surface, the anatomical constraint for the source dipoles, is extracted from magnetic resonance imaging (MRI) scans. EEG beamforming is implemented in a set of simulated data and compared for three different head models: single sphere, multi-shell sphere and realistic geometry multi-shell model that employs a boundary element method. Beamformer performance is also analyzed and evaluated for multiple dipoles and extended sources (patches). We show that using anatomical constraints with the beamforming algorithm greatly reduces computation time while increasing the spatial accuracy of the reconstructed sources of neural activity. Using the spatial Laplacian instead of the electric potential in combination with beamforming further improves the spatial resolution and allows for the detection of highly correlated sources.
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Date Issued: 2010
PURL: http://purl.flvc.org/FAU/1930497
Subject Headings: Sensorimotor integration, Brain mapping, Perceptual-motor processes
Format: Document (PDF)

Title: Gravitational signature of core-collapse supernova results of CHIMERA simulations.
Creator: Yakunin, Konstantin., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: Core-collapse supernovae (CCSN) are among the most energetic explosions in the universe, liberating ~1053 erg of gravitational binding energy of the stellar core. Most of this energy ( ~99%) is emitted in neutrinos and only 1% is released as electromagnetic radiation in the visible spectrum. Energy radiated in the form of gravitational waves (GWs) is about five orders smaller. Nevertheless, this energy corresponds to a very strong GW signal and, because of this CCSN are considered as one of...
Show moreCore-collapse supernovae (CCSN) are among the most energetic explosions in the universe, liberating ~1053 erg of gravitational binding energy of the stellar core. Most of this energy ( ~99%) is emitted in neutrinos and only 1% is released as electromagnetic radiation in the visible spectrum. Energy radiated in the form of gravitational waves (GWs) is about five orders smaller. Nevertheless, this energy corresponds to a very strong GW signal and, because of this CCSN are considered as one of the prime sources of gravitational waves for interferometric detectors. Gravitational waves can give us access to the electromagnetically hidden compact inner core of supernovae. They will provide valuable information about the angular momentum distribution and the baryonic equation of state, both of which are uncertain. Furthermore, they might even help to constrain theoretically predicted SN mechanisms. Detection of GW signals and analysis of the observations will require realistic signal predi ctions from the non-parameterized relativistic numerical simulations of CCSN. This dissertation presents the gravitational wave signature of core-collapse v supernovae. Previous studies have considered either parametric models or nonexploding models of CCSN. This work presents complete waveforms, through the explosion phase, based on first-principles models for the first time. We performed 2D simulations of CCSN using the CHIMERA code for 12, 15, and 25M non-rotating progenitors. CHIMERA incorporates most of the criteria for realistic core-collapse modeling, such as multi-frequency neutrino transport coupled with relativistic hydrodynamics, eective GR potential, nuclear reaction network, and an industry-standard equation of state., Based on the results of our simulations, I produced the most realistic gravitational waveforms including all postbounce phases of core-collapse supernovae: the prompt convection, the stationary accretion shock instability, and the corresponding explosion. Additionally, the tracer particles applied in the analysis of the GW signal reveal the origin of low-frequency component in the prompt part of gravitational waveform. Analysis of detectability of the GW signature from a Galactic event shows that the signal is within the band-pass of current and future GW observatories such as AdvLIGO, advanced Virgo, and LCGT.
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Date Issued: 2011
PURL: http://purl.flvc.org/FAU/3322512
Subject Headings: Mathematical physics, Continuum mechanics, Supernovae, Mathematical models
Format: Document (PDF)

Title: A characterization of the LAP Aquarius Phantom for external LAP laser alignment and magnetic resonance geometric distortion verification for stereotactic radiation surgery patient simulation.
Creator: Vergara, Daniel, Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: The Thesis explores additional applications of LAP's Aquarius external laser alignment verification Phantom by examining geometric accuracy of magnetic resonance images commonly used for planning intracranial stereotactic radiation surgery (ICSRS) cases. The scans were performed with MRI protocols used for ICSRS, and head and neck diagnosis, and their images fused to computerized tomographic (CT) images. The geometric distortions (GDs) were measured against the CT in all axial, sagittal, and...
Show moreThe Thesis explores additional applications of LAP's Aquarius external laser alignment verification Phantom by examining geometric accuracy of magnetic resonance images commonly used for planning intracranial stereotactic radiation surgery (ICSRS) cases. The scans were performed with MRI protocols used for ICSRS, and head and neck diagnosis, and their images fused to computerized tomographic (CT) images. The geometric distortions (GDs) were measured against the CT in all axial, sagittal, and coronal directions at different levels. Using the Aquarius Phantom, one is able to detect GD in ICSRS planning MRI acquisitions, and align the external LAP patient alignment lasers, by following the LAP QA protocol. GDs up to about 2 mm are observed at the distal regions of the longitudinal axis in the SRS treatment planning MR images. Based on the results, one may recommend the use of the Aquarius Phantom to determine if margins should be included for SRS treatment planning.
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Date Issued: 2012
PURL: http://purl.flvc.org/FAU/3352878
Subject Headings: Radiotherapy, Techniques, Medical physics, Imaging systems in medicine, Tomographic images, Computerized axial tomography
Format: Document (PDF)

Title: A method of verification of the total treatment time for the APBI (Accelerated Partial Breast Irradiation) devices: CONTURA Multilumen Balloon and SAVI Applicator.
Creator: Kyriacou, Andreas, Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: A simple method to verify the total treatment time generated by the treatment planning system (TPS) when the CONTURA MLB or the SAVI applicator are used for APBI treatments has been developed. The method compares the time generated by the TPS to a predicted time, calculated by inserting parameters obtained from the TPS in equations generated in this Thesis. The equations were generated by linearly fitting data from clinical cases that had been treated using the Contura MLB or the SAVI...
Show moreA simple method to verify the total treatment time generated by the treatment planning system (TPS) when the CONTURA MLB or the SAVI applicator are used for APBI treatments has been developed. The method compares the time generated by the TPS to a predicted time, calculated by inserting parameters obtained from the TPS in equations generated in this Thesis. The equations were generated by linearly fitting data from clinical cases that had been treated using the Contura MLB or the SAVI applicator at the Lynn Cancer Institute of the Boca Raton Regional Hospital. The parameters used were the PTV coverage, Air Kerma Strength, Balloon Volume (Contura data fit) and Evaluation PTV (SAVI data fit). As an outcome of this research, it is recommended that the plan should be reevaluated when the percent difference between the generated and the predicted times exceeds 5% for the Contura MLB, or 10% for the SAVI.
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Date Issued: 2011
PURL: http://purl.flvc.org/FAU/3332254
Subject Headings: Cancer, Radiotherapy, Breast, Cancer, Radiotherapy, Breast, Cancer, Treatment
Format: Document (PDF)

Title: Subjecting the CHIMERA supernova code to two hydrodynamic test problems, (i) Riemann problem and (ii) Point blast explosion.
Creator: Ahsan, Abu Salah M., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: A Shock wave as represented by the Riemann problem and a Point-blast explosion are two key phenomena involved in a supernova explosion. Any hydrocode used to simulate supernovae should be subjected to tests consisting of the Riemann problem and the Point-blast explosion. L. I. Sedov's solution of Point-blast explosion and Gary A. Sod's solution of a Riemann problem have been re-derived here from one dimensional fluid dynamics equations . Both these problems have been solved by using the idea...
Show moreA Shock wave as represented by the Riemann problem and a Point-blast explosion are two key phenomena involved in a supernova explosion. Any hydrocode used to simulate supernovae should be subjected to tests consisting of the Riemann problem and the Point-blast explosion. L. I. Sedov's solution of Point-blast explosion and Gary A. Sod's solution of a Riemann problem have been re-derived here from one dimensional fluid dynamics equations . Both these problems have been solved by using the idea of Self-similarity and Dimensional analysis. The main focus of my research was to subject the CHIMERA supernova code to these two hydrodynamic tests. Results of CHIMERA code for both the blast wave and Riemann problem have then been tested by comparing with the results of the analytic solution.
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Date Issued: 2008
PURL: http://purl.flvc.org/FAU/172665
Subject Headings: Mathematical physics, Continuum mechanics, Number theory, Supernovae, Data processing, Shock waves, Fluid dynamics
Format: Document (PDF)

Title: Synchronization and phase dynamics of oscillating foils.
Creator: Finkel, Cyndee L., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: In this work, a two-dimensional model representing the vortices that animals produce, when they are flying/swimming, was constructed. A D{shaped cylinder and an oscillating airfoil were used to mimic these body{shed and wing{generated vortices, respectively. The parameters chosen are based on the Reynolds numbers similar to that which is observed in nature (104). In order to imitate the motion of ying/swimming, the entire system was suspended into a water channel from frictionless air...
Show moreIn this work, a two-dimensional model representing the vortices that animals produce, when they are flying/swimming, was constructed. A D{shaped cylinder and an oscillating airfoil were used to mimic these body{shed and wing{generated vortices, respectively. The parameters chosen are based on the Reynolds numbers similar to that which is observed in nature (104). In order to imitate the motion of ying/swimming, the entire system was suspended into a water channel from frictionless air{bearings. The position of the apparatus in the channel was regulated with a linear, closed loop PI controller. Thrust/drag forces were measured with strain gauges and particle image velocimetry (PIV) was used to examine the wake structure that develops. The Strouhal number of the oscillating airfoil was compared to the values observed in nature as the system transitions between the accelerated and steady states... As suggested by previous work, this self-regulation is a result of a limit cycle process that stems from nonlinear periodic oscillations. The limit cycles were used to examine the synchronous conditions due to the coupling of the foil and wake vortices. Noise is a factor that can mask details of the synchronization. In order to control its effect, we study the locking conditions using an analytic technique that only considers the phases.. The results suggest that Strouhal number selection in steady forward natural swimming and flying is the result of a limit cycle process and not actively controlled by an organism. An implication of this is that only relatively simple sensory and control hardware may be necessary to control the steady forward motion of man-made biomimetically propelled vehicles.
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Date Issued: 2013
PURL: http://purl.flvc.org/fcla/dt/3362333
Subject Headings: Mathematical physics, Fluid dynamics, Unsteady flow (Fluid dynamics), Aerofoils, Aerodynamics
Format: Document (PDF)

Title: Reduced representation of neural networks.
Creator: Stefanescu, Roxana A., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: Experimental and computational investigations addressing how various neural functions are achieved in the brain converged in recent years to a unified idea that the neural activity underlying most of the cognitive functions is distributed over large scale networks comprising various cortical and subcortical areas. Modeling approaches represent these areas and their connections using diverse models of neurocomputational units engaged in graph-like or neural field-like structures. Regardless of...
Show moreExperimental and computational investigations addressing how various neural functions are achieved in the brain converged in recent years to a unified idea that the neural activity underlying most of the cognitive functions is distributed over large scale networks comprising various cortical and subcortical areas. Modeling approaches represent these areas and their connections using diverse models of neurocomputational units engaged in graph-like or neural field-like structures. Regardless of the manner of network implementation, simulations of large scale networks have encountered significant difficulties mainly due to the time delay introduced by the long range connections. To decrease the computational effort, it is common to assume severe approximations to simplify the descriptions of the neural dynamics associated with the system's units. In this dissertation we propose an alternative framework allowing the prevention of such strong assumptions while efficiently representing th e dynamics of a complex neural network. First, we consider the dynamics of small scale networks of globally coupled non-identical excitatory and inhibitory neurons, which could realistically instantiate a neurocomputational unit. We identify the most significant dynamical features the neural population exhibits in different parametric configuration, including multi-cluster dynamics, multi-scale synchronization and oscillator death. Then, using mode decomposition techniques, we construct analytically low dimensional representations of the network dynamics and show that these reduced systems capture the dynamical features of the entire neural population. The cases of linear and synaptic coupling are discussed in detail. In chapter 5, we extend this approach for spatially extended neural networks., We consider the dynamical behavior of a neural field-like network, which incorporates many biologically realistic characteristics such as heterogeneous local and global connectivity as well as dispersion in the neural membrane excitability. We show that in this case as well, we can construct a reduced representation, which may capture well the dynamical features of the full system. The method outlined in this dissertation provides a consistent way to represent complex dynamical features of various neural networks in a computationally efficient manner.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/369387
Subject Headings: Molecular neurobiology, Neural networks (Neurobiology), Brain, Mathematical models, Cognitive neuroscience, Recognition (Psychology)
Format: Document (PDF)

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