Current Search: Motion (x)
Pages
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Title
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Wind effect on super-tall buildings using computational fluid dynamics and structural dynamics.
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Creator
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Assaad, Bilal, Arockiasamy, Madasamy, Florida Atlantic University, College of Engineering and Computer Science, Department of Civil, Environmental and Geomatics Engineering
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Abstract/Description
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Super-tall buildings located in high velocity wind regions are highly vulnerable to large lateral loads. Designing for these structures must be done with great engineering judgment by structural professionals. Present methods of evaluating these loads are typically by the use of American Society of Civil Engineers 7-10 standard, field measurements or scaled wind tunnel models. With the rise of high performance computing nodes, an emerging method based on the numerical approach of...
Show moreSuper-tall buildings located in high velocity wind regions are highly vulnerable to large lateral loads. Designing for these structures must be done with great engineering judgment by structural professionals. Present methods of evaluating these loads are typically by the use of American Society of Civil Engineers 7-10 standard, field measurements or scaled wind tunnel models. With the rise of high performance computing nodes, an emerging method based on the numerical approach of Computational Fluid Dynamics has created an additional layer of analysis and loading prediction alternative to conventional methods. The present document uses turbulence modeling and numerical algorithms by means of Reynolds-averaged Navier-Stokes and Large Eddy Simulation equations applied to a square prismatic prototype structure in which its dynamic properties have also been investigated. With proper modeling of the atmospheric boundary layer flow, these numerical techniques reveal important aerodynamic properties and enhance flow visualization to structural engineers in a virtual environment.
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Date Issued
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2015
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PURL
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http://purl.flvc.org/fau/fd/FA00004343, http://purl.flvc.org/fau/fd/FA00004343
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Subject Headings
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Boundary layer control, Buildings -- Aerodynamics, Computational fluid dynamics, Structural dynamics -- Data processing, Vortex motion
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Format
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Document (PDF)
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Title
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The influrence of language on recognition memory for motion.
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Creator
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Karaman, Ferhat., Charles E. Schmidt College of Science, Department of Psychology
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Abstract/Description
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Satellite-framed languages and verb-framed languages differ in how they encode motion events. English encodes or lexicalizes Path in verb particles, prepositional phrases, or satellites associated with the main verb. In contrast, Turkish tends to encode Path in the main verb of a clause. When describing motion events, English speakers typically use verbs that convey information about manner rather than path, whereas Turkish speakers do the opposite. In this study, we investigated whether this...
Show moreSatellite-framed languages and verb-framed languages differ in how they encode motion events. English encodes or lexicalizes Path in verb particles, prepositional phrases, or satellites associated with the main verb. In contrast, Turkish tends to encode Path in the main verb of a clause. When describing motion events, English speakers typically use verbs that convey information about manner rather than path, whereas Turkish speakers do the opposite. In this study, we investigated whether this crosslinguistic difference between English and Turkish influences how the speakers of these languages perform in a non-linguistic recognition memory task. In a video description task, English speakers used more manner verbs in the main verb of sentences than Turkish speakers did. In the recognition memory task, English speakers attended more strongly than Turkish speakers did to path of motion. English and Turkish speakers attended equally to manner of motion, however, providing no support for the linguistic relativity hypothesis.
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Date Issued
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2013
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PURL
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http://purl.flvc.org/fcla/dt/3362478
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Subject Headings
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Psycholinguistics, Computational neuroscience, Cognitive psychology, Context effects (Psychology), Transference (Psychology), Motion segmentation
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Format
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Document (PDF)
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Title
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The influence of motion type on memory of simple events.
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Creator
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Berger, Johanna D., Charles E. Schmidt College of Science, Department of Psychology
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Abstract/Description
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This experiment investigated an individual's memory of specific motion events, unique actor, intrinsic motion, and extrinsic motion combination. Intrinsic motions involve the movement of an individual's body parts in a specific manner to move around, while extrinsic motions specify a path in reference to an external object. Participants viewed video clips, each depicting an actor performing a unique extrinsic and intrinsic motion combination. One week later, they viewed a different series of...
Show moreThis experiment investigated an individual's memory of specific motion events, unique actor, intrinsic motion, and extrinsic motion combination. Intrinsic motions involve the movement of an individual's body parts in a specific manner to move around, while extrinsic motions specify a path in reference to an external object. Participants viewed video clips, each depicting an actor performing a unique extrinsic and intrinsic motion combination. One week later, they viewed a different series of retrieval video clips consisting of old (identical to encoding), extrinsic conjunction (extrinsic motion previously performed by different actor), intrinsic conjunction (intrinsic motion previously performed by different actor), and new (novel extrinsic or intrinsic motion) video clips. Participants responded "yes" to viewing the old video clips the most often, followed by conjunction video clips, and then new video clips. Furthermore, there were a greater number of "yes" event memory recognition responses for extrinsic conjunction items than intrinsic conjunction items.
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Date Issued
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2009
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PURL
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http://purl.flvc.org/FAU/186673
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Subject Headings
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Recollection (Psychology), Context effects (Psychology), Memory, Research, Human information processing, Research, Transference (Psychology), Motion segmentation
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Format
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Document (PDF)
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Title
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A low-cost, high rate motion measurement system for an unmanned surface vehicle with underwater navigation and oceanographic applications.
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Creator
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Gelin, Chrystel., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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Standard GPS receivers are unable to provide the rate or precision required when used on a small vessel such as an Unmanned Surface Vehicles (USVs). To overcome this, the thesis presents a low cost high rate motion measurement system for an USV with underwater and oceanographic purposes. The work integrates an Inertial Measurement Unit (IMU), a GPS receiver, a flux-gate compass, a tilt sensor and develops a software package, using real time data fusion methods, for an USV to aid in the...
Show moreStandard GPS receivers are unable to provide the rate or precision required when used on a small vessel such as an Unmanned Surface Vehicles (USVs). To overcome this, the thesis presents a low cost high rate motion measurement system for an USV with underwater and oceanographic purposes. The work integrates an Inertial Measurement Unit (IMU), a GPS receiver, a flux-gate compass, a tilt sensor and develops a software package, using real time data fusion methods, for an USV to aid in the navigation and control as well as controlling an onboard Acoustic Doppler Current Profiler (ADCP).While ADCPs non-intrusively measure water flow, they suffer from the inability to discriminate between motions in the water column and self-motion. Thus, the vessel motion contamination needs to be removed to analyze the data and the system developed in this thesis provides the motion measurements and processing to accomplish this task.
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Date Issued
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2010
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PURL
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http://purl.flvc.org/FAU/2709690
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Subject Headings
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Oceanographic instruments, Evaluation, Underwater navigation, Adaptive signal processing, Inertial navigation systems, Wave motion, Theory of
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Format
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Document (PDF)
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Title
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Investigation of trapped vortex combustion using hydrogen-rich fuels.
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Creator
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Zbeeb, Khaled., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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The combustion process of a fuel is a challenging subject when it comes to analyze its performance and resultant emissions. The main task of this study is to optimize the selection of a hydrogen-rich fuel based on its performance and emissions. Computational Fluid Dynamics analysis is performed to test the combustion performance and emissions from the vortex trapped combustor when natural gas fuel (methane) is replaced with renewable and alternative fuels such as hydrogen and synthesis gas....
Show moreThe combustion process of a fuel is a challenging subject when it comes to analyze its performance and resultant emissions. The main task of this study is to optimize the selection of a hydrogen-rich fuel based on its performance and emissions. Computational Fluid Dynamics analysis is performed to test the combustion performance and emissions from the vortex trapped combustor when natural gas fuel (methane) is replaced with renewable and alternative fuels such as hydrogen and synthesis gas. Correlation graphs for the trapped vortex combustor performance and NOx, CO, and CO2 emissions for various types of fuels with different compositions and heat of combustion values were established. Methane, Hydrogen and 10 different syngas fuels were analyzed in this study using computational fluid dynamics numerical method. The trapped vortex combustor that represents an efficient and compact combustor for flame stability was investigated. The TVC consists of a fore body and two after body disks . These components are all encircled with a Pyrex tube. The purpose of the after body disks is to create the vortex wakes that will enhance the combustion process and minimize the NOx emissions. The TVC CFD model was validated by comparing the CFD model results using propane fuel with existing experimental results that were established in Rome, Italy. The static temperature distribution and NOx, CO emissions, combustor efficiency and total pressure drop results of the three dimensional CFD model were similar to the experimental data. Effects of H2/CO and H2/CH4 ratios and the mass fraction of each constituent of syngas fuels and Hydrogen-Methane fuel mixture on the TVC performance and emissions were investigated., Moreover, the fuel injector Reynolds number and Lower heating values for Methane, Hydrogen and 10 syngas fuels on the TVC performance and emissions were also investigated. Correlation plots for the NOx, CO and CO2 emissions versus the fuel injector Reynolds number and low heating value were established. These correlation curves can be used as a fair design diagram to optimize the fuel selection process for aerospace and electrical power plant applications.
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Date Issued
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2011
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PURL
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http://purl.flvc.org/FAU/3334096
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Subject Headings
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Hydrogen as fuel, Research, Combustion chambers, Vortex-motion, Fluid dynamics
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Format
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Document (PDF)
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Title
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Propulsive Performance and Maneuver Control of Undulatory Ribbon Fin Propulsion Using Bio-inspired Robotic Systems.
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Creator
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Liu, Hanlin, Curet, Oscar M., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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Undulatory ribbon- n-based propulsion is an appealing propulsion mechanism due to its rich locomotor capabilities that can improve the propulsive performance and maneuverability of underwater vehicles. For instance, the swimming mechanics of weakly electric black ghost knife sh (Apteronotus albifrons) is of great interest to study because of their high swimming e ciency at low speeds and extraordinary agility such as rapid reversal swimming, hovering in presence of water disturbance, rolling...
Show moreUndulatory ribbon- n-based propulsion is an appealing propulsion mechanism due to its rich locomotor capabilities that can improve the propulsive performance and maneuverability of underwater vehicles. For instance, the swimming mechanics of weakly electric black ghost knife sh (Apteronotus albifrons) is of great interest to study because of their high swimming e ciency at low speeds and extraordinary agility such as rapid reversal swimming, hovering in presence of water disturbance, rolling and vertical swimming. In this thesis work, to facilitate our understanding on the exible undulatory ribbon n propulsion, we have four research motivations. The rst objective is to study how the use of exible rays and di erent n morphology can in uence the propulsive performance of ribbon- n propulsion. It is possible that natural swimmers using this locomotion method could take advantage of passive n motion based on the coupling of uid-structure interaction and the elasto-mechanical responses of the undulating n. Therefore, the second objective is to understand how an under-actuated undulating n can take advantage of natural dynamics of the uid-structure interaction for the propulsive force generation. In addition to the impressive propulsive performance of the undulatory n propulsion, the exceptional maneuverability of knife sh is also a key motivation that drives this thesis work. Thus, we dedicate to investigate how traveling wave shapes and actuation parameters (frequency, wavelength) can manipulate the maneuvering behaviors of a swimmer propelled by an undulating ribbon n. Lastly, we aim to uncover the e ect of varying traveling wave amplitudes and pectoral ns on its maneuvering performances. Two robotic devices were developed to study the propulsive performance of both fullyactuated and under-actuated ribbon n propulsion and investigate the maneuver control of a free-swimming underwater robot propelled by an undulatory n. For the rst research aim, we study the e ect of exible rays and di erent n morphology on the propulsive performance of ribbon- n propulsion. A physical model composed of fteen rays interconnected with an elastic membrane was used to test four di erent ray exural sti ness and four aspect ratios. Our results show that exible rays can improve the propulsive e ciency compared to a rigid counterpart. In addition, the morphology of the ribbon n a ects its propulsive performance as well, and there could exist an optimal n morphology. To understand how an underactuated undulating n can modify its active and passive n motion to e ectively control the hydrodynamic force and propulsive e ciency. We did a series of experiments using the same robotic n model but with some structural modi cations and we measured n kinematics, net surge force and power consumption. We nd that the under-actuated n can keep the equivalent propulsive e ciency as the fully-actuated counterpart within our experimental parameter range. Moreover, our results demonstrate that the thrust force and power consumption of an under-actuated n follow the same scaling laws as the fully-actuated n. To conduct the free-swimming maneuver study, we developed a self-contained, free-swimming robot propelled by an undulatory n, which is able to perform the following maneuvers: forward, reversed swimming and hovering motion. We also performed V3V PIV experiments to capture the ow structures generated by the robotic device. Our results show that the robot can reach higher swimming e ciency at low frequencies. As the number of traveling waves increases, the robot swims more stably in roll, pitch and yaw motions. For cases with varying wave amplitudes, traveling wave with incremental wave amplitude can achieve free-swimming velocity higher than that of decremental wave amplitude. However, the latter case can generate higher pitch angles. For the robot with slightly negative-pitched pectoral ns, it can perform slow diving maneuvers. These ndings demonstrate that we can take advantage of the undulating ribbon n propulsion to achieve high maneuverability for the future underwater vehicles in complex environment.
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Date Issued
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2017
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PURL
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http://purl.flvc.org/fau/fd/FA00004853, http://purl.flvc.org/fau/fd/FA00004853
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Subject Headings
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Underwater propulsion., Wave-motion, Theory of., Remote submersibles--Design., Marine engineering.
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Format
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Document (PDF)
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Title
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Hydrodynamic analysis of underwater bodies for efficient station keeping in shallow waters with surface waves.
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Creator
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Bradley, Matthew, Ananthakrishnan, Palaniswamy, Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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To determine the effect of body shape on the response of underwater vehicles to surface waves in shallow water, the wave radiation hydrodynamic forces are evaluated for a family of (i) prolate spheroidal hull forms and (ii) cylindrical bodies with hemispherical nose and conical tail sections by systematically varying the geometric parameters but keeping displacement constant. The added-mass and wave damping coefficients are determined using a frequency-domain, simple-source based boundary...
Show moreTo determine the effect of body shape on the response of underwater vehicles to surface waves in shallow water, the wave radiation hydrodynamic forces are evaluated for a family of (i) prolate spheroidal hull forms and (ii) cylindrical bodies with hemispherical nose and conical tail sections by systematically varying the geometric parameters but keeping displacement constant. The added-mass and wave damping coefficients are determined using a frequency-domain, simple-source based boundary integral method. Results are obtained for a range of wave frequencies and depths of vehicle submergence all for a fixed water depth of 10 m. With the wave exciting force and moment determined using the Froude-Krylov theory, the response transfer functions for heave and pitch are then determined. The heave and pitch response spectra in actual littoral seas are then determined with the sea state modeled using TMA spectral relations. Results show that vehicle slenderness is a key factor affecting the hydrodynamic coefficients and response. The results show two characteristics that increase the radiation hydrodynamic forces corresponding to heave and pitch motions: namely, vehicle length and further-away from mid-vehicle location of the body shoulder. The opposite is true for the oscillatory surge motion. By utilizing these observed characteristics, one can design the lines for maximum radiation forces and consequently minimum hull response for the critical modes of rigid-body motion in given waters and vehicle missions. In the studies carried out in the thesis, a hull with a long parallel middle body with hemispherical nose and conical tail sections has better heave and pitch response characteristics compared prolate spheroid geometry of same volume. The methodology developed herein, which is computationally efficient, can be used to determine optimal hull geometry for minimal passive vehicle response in a given sea.
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Date Issued
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2014
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PURL
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http://purl.flvc.org/fau/fd/FA00004084, http://purl.flvc.org/fau/fd/FA00004084
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Subject Headings
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Oceanographic submersibles -- Hydrodynamics, Surface waves (Oceanography) -- Mathematical models, Wave motion, Theory of
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Format
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Document (PDF)
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Title
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Dancing beneath the surface: Men, masculinity and expressions of the feminine.
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Creator
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Hodapp, Christa M., Florida Atlantic University, Caputi, Jane
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Abstract/Description
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The masculine gender identity in western United States culture is constructed in opposition to femininity, and is maintained through the culture modes of discipline and surveillance. However, instances of male femininity challenge these rigid constructs of gender, and suggest that gender is in fact a performance reflecting cultural norms as opposed to an internal core of identity. Instances of male femininity can be located in heterosexual male cross-dressing activities, ranging from the...
Show moreThe masculine gender identity in western United States culture is constructed in opposition to femininity, and is maintained through the culture modes of discipline and surveillance. However, instances of male femininity challenge these rigid constructs of gender, and suggest that gender is in fact a performance reflecting cultural norms as opposed to an internal core of identity. Instances of male femininity can be located in heterosexual male cross-dressing activities, ranging from the recent phenomena of "metrosexuality" to heterosexual men completely dressing as women. While frequently presenting some problematic conceptions of gender, these behaviors also provide instances of subversive breaks in gendered performance, and illustrate the possibility for a non-oppositional heterosexuality. Additionally, the films Billy Elliot and Matthew Bourne's Swan Lake provide popular culture examples illustrating the ways in which men struggle with masculinity, and the complexities of addressing moments of femininity in individual male subjectivity and identity.
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Date Issued
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2004
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PURL
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http://purl.flvc.org/fcla/dt/13126
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Subject Headings
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Gender identity in motion pictures, Masculinity, Cross-dressing, Men--Identity
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Format
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Document (PDF)
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Title
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Deterministic, stochastic and convex analyses of one- and two-dimensional periodic structures.
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Creator
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Zhu, Liping., Florida Atlantic University, Lin, Y. K., Elishakoff, Isaac, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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The periodic structures considered in the dissertation are one-dimensional periodic multi-span beams, and two-dimensional periodic grillages with elastic interior supports. The following specific topics are included: (1) Deterministic Vibration--Exact solutions are obtained for free vibrations of both multi-span beams and grillages, by utilizing the wave propagation concept. The wave motions at the periodic supports/nodes are investigated and the dispersion equations are derived from which...
Show moreThe periodic structures considered in the dissertation are one-dimensional periodic multi-span beams, and two-dimensional periodic grillages with elastic interior supports. The following specific topics are included: (1) Deterministic Vibration--Exact solutions are obtained for free vibrations of both multi-span beams and grillages, by utilizing the wave propagation concept. The wave motions at the periodic supports/nodes are investigated and the dispersion equations are derived from which the natural frequencies of the periodic structures are determined. The emphasis is placed on the calculation of mode shapes of both types of periodic structures. The general expressions for mode shapes with various boundary conditions are obtained. These mode shapes are used to evaluate the exact dynamic response to a convected harmonic loading. (2) Stochastic Vibration--A multi-span beam under stochastic acoustic loading is considered. The exact analytical expressions for the spectral densities are derived for both displacement and bending moment by using the normal mode approach. Nonlinear vibration of a multi-span beam with axial restraint and initial imperfection are also investigated. In the latter case, the external excitation is idealized as a Gaussian white nose. An expression for the joint probability density function in the generalized coordinates is obtained and used to evaluate the mean square response of a multi-span beam system. (3) Convex Modeling of Uncertain Excitation Field--It is assumed that the parameters of the stochastic excitation field are uncertain and belong to a multi-dimensional convex set. A new approach is developed to determine the multi-dimensional ellipsoidal convex set with a minimum volume. The most and least favorable responses of a multi-span beam are then determined for such a convex set, corresponding to a stochastic acoustic field. The procedure is illustrated in several examples.
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Date Issued
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1994
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PURL
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http://purl.flvc.org/fcla/dt/12366
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Subject Headings
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Grillages (Structural engineering), Girders--Vibration, Wave-motion, Theory of, Vibration
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Format
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Document (PDF)
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Title
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Dynamic analysis of single- and multi-module platforms in waves.
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Creator
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Kling, Kaylie Ann., Florida Atlantic University, Ananthakrishnan, Palaniswamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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The response of single- and multi-module floating platforms to surface waves is investigated theoretically. Wave exciting forces are computed using methods based on the Morrison equation and Froude-Krylov hypothesis. The radiation forces are obtained from experimental results of Vugt and where possible diffraction forces using the Haskind reciprocity relation. Heave and pitch response of a one-module platform and hinge-connected two-module platform are determined by integrating the...
Show moreThe response of single- and multi-module floating platforms to surface waves is investigated theoretically. Wave exciting forces are computed using methods based on the Morrison equation and Froude-Krylov hypothesis. The radiation forces are obtained from experimental results of Vugt and where possible diffraction forces using the Haskind reciprocity relation. Heave and pitch response of a one-module platform and hinge-connected two-module platform are determined by integrating the corresponding equations of rigid-body motion. A structural dynamic analysis is also carried out using the Green's function method to determine the elastic flexural response of the platform to waves. The results are compared with the experimental and numerical findings of others. The thesis contributes to a better understanding of rigid-body and elastic response of large ocean platforms subject to wave forces. The methodology is computationally less intensive and therefore can be effectively used for the design of platforms and the validation of numerical algorithms.
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Date Issued
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2006
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PURL
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http://purl.flvc.org/fcla/dt/13399
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Subject Headings
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Ocean engineering, Wave motion, Theory of, Water waves--Mathematical models, Drilling platforms, Extreme value theory
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Format
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Document (PDF)
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Title
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Disney's representations of gender and family in three animated films: The construction of myth in popular culture.
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Creator
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Siemens, Linda Beth., Florida Atlantic University, Budd, Michael N.
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Abstract/Description
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The tremendous changes in the lives of American women and the dynamics of the American family have gone unnoticed by Disney in some of its animated films. Aside from a few superficial changes, representations of Disney's heroines consistently depict them within the limiting boundaries of stereotypically traditional women. Disney's families also remain firmly within the traditional patriarchal mold. This thesis applies ideological film criticism to Disney's films The Little Mermaid (1989),...
Show moreThe tremendous changes in the lives of American women and the dynamics of the American family have gone unnoticed by Disney in some of its animated films. Aside from a few superficial changes, representations of Disney's heroines consistently depict them within the limiting boundaries of stereotypically traditional women. Disney's families also remain firmly within the traditional patriarchal mold. This thesis applies ideological film criticism to Disney's films The Little Mermaid (1989), Beauty and the Beast (1991), and The Hunchback of Notre Dame (1996), in the contention that these films function to refine and promote a static, sexist, and decidedly patriarchal myth.
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Date Issued
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2002
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PURL
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http://purl.flvc.org/fcla/dt/12956
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Subject Headings
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Walt Disney Company, Animated films--Criticism and interpretation, Popular culture, Women in motion pictures
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Format
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Document (PDF)
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Title
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THE EMISSION OF SOFT X-RAYS FROM MASSIVE GALACTIC HALOS.
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Creator
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PENLAND, MARY CECILE., Florida Atlantic University
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Abstract/Description
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The assumption that the entire velocity rotation curve is due to a massive, spherical galactic halo (massive halo hypothesis) is used to construct a model of discrete soft x-ray emitting sources. Hot white dwarfs and flaring red dwarfs were found to have sufficient luminosity to account for the observed x-ray intensity. However, the distribution of these sources as dictated by the massive halo hypothesis is such that the observed latitude dependence of the x-ray intensity is not reproduced....
Show moreThe assumption that the entire velocity rotation curve is due to a massive, spherical galactic halo (massive halo hypothesis) is used to construct a model of discrete soft x-ray emitting sources. Hot white dwarfs and flaring red dwarfs were found to have sufficient luminosity to account for the observed x-ray intensity. However, the distribution of these sources as dictated by the massive halo hypothesis is such that the observed latitude dependence of the x-ray intensity is not reproduced. Emission from a hot coronal gas also fails to reproduce the observed latitude dependence of the soft x-ray intensity; however, the crudity of the model of the hot coronal gas precludes any definite conclusions.
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Date Issued
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1977
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PURL
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http://purl.flvc.org/fcla/dt/13877
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Subject Headings
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Interstellar matter--Optical properties, Galaxies--Motion in line of sight
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Format
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Document (PDF)
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Title
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Temporal and spatial determinants of induced shifts in perceived position.
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Creator
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Eastman, Kathleen E., Florida Atlantic University, Hock, Howard S.
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Abstract/Description
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The effects of the onset, offset, and sustained presence of inducing lines on the perceived position of test lines were independently investigated in a vernier alignment task. For spatial separations larger than 2.3 min, repulsion effects were always observed. For the smallest spatial separation, 2.3 min, the effect of the inducing lines was attraction for 0 and 195 SOAs. Minimal attraction was observed for a 3000 SOA. However, when the offset effect was isolated using the 3000 SOA and a 0...
Show moreThe effects of the onset, offset, and sustained presence of inducing lines on the perceived position of test lines were independently investigated in a vernier alignment task. For spatial separations larger than 2.3 min, repulsion effects were always observed. For the smallest spatial separation, 2.3 min, the effect of the inducing lines was attraction for 0 and 195 SOAs. Minimal attraction was observed for a 3000 SOA. However, when the offset effect was isolated using the 3000 SOA and a 0 ISI, a large repulsion effect was observed for the 2.3 min spatial separation, as well as for the larger spatial separations. These results indicate that the temporal separation between visual elements is as important in determining perceived position as their spatial separation, which has been demonstrated in earlier studies (Badcock & Westheimer, 1985). A differential gradient model is proposed which accounts for these findings in terms of excitatory and inhibitory interactions within an ensemble of position-sensitive units.
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Date Issued
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1993
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PURL
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http://purl.flvc.org/fcla/dt/14897
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Subject Headings
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Visual perception, Space perception, Motion perception (Vision), Figure-ground perception
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Format
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Document (PDF)
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Title
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An experimental study of vortex response during cutting by a blade or cylinder.
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Creator
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Krishnamoorthy, Srikanth., Florida Atlantic University, Marshall, Jeffrey S., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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An experimental study of the vortex response to interaction with and cutting by a thin flat plate or circular cylinders of various diameters has been performed. The direction of motion of the flat plate (or circular cylinder) is normal to the vortex axis in the experiments. The vortex is generated by withdraw of fluid at an orifice at the bottom of an "inner cylinder" immersed in a rectangular tank, and the flow field is visualized with both water soluble and immiscible dyes. In the...
Show moreAn experimental study of the vortex response to interaction with and cutting by a thin flat plate or circular cylinders of various diameters has been performed. The direction of motion of the flat plate (or circular cylinder) is normal to the vortex axis in the experiments. The vortex is generated by withdraw of fluid at an orifice at the bottom of an "inner cylinder" immersed in a rectangular tank, and the flow field is visualized with both water soluble and immiscible dyes. In the experiments with circular cylinders, the bending of the vortex is compared to computational predictions from [15], and the mechanism of subsequent breakup of the vortex as it gets closer to the cylinder is studied. The vortex is observed to bend farther without breakup for larger forward speeds of the circular cylinder. Very little bending is observed when the vortex interacts with the flat plate, except for angles of attack exceeding the stall limit Following cutting of the vortex by the flat plate or circular cylinder, a vortex shock is observed to form and propagate up the vortex axis. No vortex shock is observed on the opposite side of the blade. The various forms of these vortex shocks have been photographed, and they appear very similar to travelling vortex breakdowns. The propagation speed of the shocks is compared to an analytical solution for instantaneous vortex cutting by a flat plate of zero thickness.
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Date Issued
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1993
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PURL
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http://purl.flvc.org/fcla/dt/14977
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Subject Headings
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Vortex-motion, Blades--Noise, Cylinders, Rotors (Helicopters), Helicopters--Noise
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Format
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Document (PDF)
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Title
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Competition between opposing motion directions in the perception of apparent motion: A new look at an old stimulus.
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Creator
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Huisman, Avia, Florida Atlantic University, Hock, Howard S.
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Abstract/Description
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This study tested the hypothesis that the perception of 2-flash apparent motion (points of light are briefly presented in succession at a nearby locations) is the outcome of competition between two opposing motion directions activated by the stimulus. Experiment 1 replicated previous results obtained using 2-flash stimuli; motion was optimal for a non-zero inter-frame interval (Kolers, 1972; Wertheimer, 1912). In Experiment 2, stimuli were pared down to a single luminance change toward the...
Show moreThis study tested the hypothesis that the perception of 2-flash apparent motion (points of light are briefly presented in succession at a nearby locations) is the outcome of competition between two opposing motion directions activated by the stimulus. Experiment 1 replicated previous results obtained using 2-flash stimuli; motion was optimal for a non-zero inter-frame interval (Kolers, 1972; Wertheimer, 1912). In Experiment 2, stimuli were pared down to a single luminance change toward the background at one location, and a single luminance change away from the background at one location at another. Results were consistent with apparent motion being specified by the counter-changing luminance; motion was optimal for a non-zero inter-frame interval. A subtractive model based on counter-change stimulating opposing motion directions did not account for the results of the 2-flash experiment. An alternative model based on the combined transient responses of biphasic detectors is discussed.
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Date Issued
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2005
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PURL
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http://purl.flvc.org/fcla/dt/13209
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Subject Headings
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Contrast sensitivity (Vision), Visual perception, Motion perception (Vision), Movement, Psychology of
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Format
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Document (PDF)
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Title
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System identification methodology for a wave adaptive modular unmanned surface vehicle.
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Creator
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Mask, Janine L., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
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Abstract/Description
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The design, implementation, and testing of an experimental setup intended to evaluate the dynamic maneuvering performance of the Wave Adaptive Modular Vessel (WAM-V) class USV12, a 3.7 meter unmanned surface vehicle (USV) is described. A comprehensive sensor package was designed, fabricated and assembled to record the vehicle's dynamic response to various control inputs. All subsystems were fabricated and installed on a test vehicle, GUSS, and full system, open-loop maneuvering tests were...
Show moreThe design, implementation, and testing of an experimental setup intended to evaluate the dynamic maneuvering performance of the Wave Adaptive Modular Vessel (WAM-V) class USV12, a 3.7 meter unmanned surface vehicle (USV) is described. A comprehensive sensor package was designed, fabricated and assembled to record the vehicle's dynamic response to various control inputs. All subsystems were fabricated and installed on a test vehicle, GUSS, and full system, open-loop maneuvering tests were conducted to show validity of data collection technique. Simulations were performed using model parameters found in the literature to create a "simulated experimental" data set, upon which system identification techniques were used to rediscover a suitable model with similar parameterization. Combined, the sensor package and the method for creating this model support future work in the design of automatic control, navigation, and guidance systems for the WAM-V USV12.
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Date Issued
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2011
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PURL
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http://purl.flvc.org/FAU/3332720
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Subject Headings
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Oceanographic instruments, Evaluation, Wave motion, Theory of, Inertial navigation systems, Adaptive signal processing
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Format
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Document (PDF)
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Title
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THE CHANGE POINT PROBLEM FOR TWO CLASSES OF STOCHASTIC PROCESSES.
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Creator
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Ball, Cory, Long, Hongwei, Florida Atlantic University, Department of Mathematical Sciences, Charles E. Schmidt College of Science
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Abstract/Description
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The change point problem is a problem where a process changes regimes because a parameter changes at a point in time called the change point. The objective of this problem is to estimate the change point and each of the parameters of the stochastic process. In this thesis, we examine the change point problem for two classes of stochastic processes. First, we consider the volatility change point problem for stochastic diffusion processes driven by Brownian motions. Then, we consider the drift...
Show moreThe change point problem is a problem where a process changes regimes because a parameter changes at a point in time called the change point. The objective of this problem is to estimate the change point and each of the parameters of the stochastic process. In this thesis, we examine the change point problem for two classes of stochastic processes. First, we consider the volatility change point problem for stochastic diffusion processes driven by Brownian motions. Then, we consider the drift change point problem for Ornstein-Uhlenbeck processes driven by _-stable Levy motions. In each problem, we establish the consistency of the estimators, determine asymptotic behavior for the changing parameters, and finally, we perform simulation studies to computationally assess the convergence of parameters.
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Date Issued
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2020
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PURL
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http://purl.flvc.org/fau/fd/FA00013462
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Subject Headings
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Stochastic processes, Change-point problems, Brownian motion processes, Ornstein-Uhlenbeck process, Computer simulation
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Format
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Document (PDF)
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Title
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Global feedback in hierarchical motion pattern formation.
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Creator
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Brownlow, Stacey W., Florida Atlantic University, Hock, Howard S., Charles E. Schmidt College of Science, Department of Psychology
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Abstract/Description
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An array of four motion quartets (stimuli for which either horizontal or vertical motion is perceived depending on quartet aspect ratio) is arranged in a diamond configuration such that two global motion patterns are formed: (1) Rotation---alternating counterclockwise and clockwise motion is perceived, and (2) Parallel path motion---the perceived motions of all the elements are simultaneously horizontal or simultaneously vertical. The perception of rotation resulted in global feedback that...
Show moreAn array of four motion quartets (stimuli for which either horizontal or vertical motion is perceived depending on quartet aspect ratio) is arranged in a diamond configuration such that two global motion patterns are formed: (1) Rotation---alternating counterclockwise and clockwise motion is perceived, and (2) Parallel path motion---the perceived motions of all the elements are simultaneously horizontal or simultaneously vertical. The perception of rotation resulted in global feedback that biases the motion perceived for an individual component motion quartet to be more consistent with rotation than aspect ratio. Stronger rotation produced greater bias. Under certain conditions, the feedback-induced bias occurred even though global rotation was not perceived. The results were interpreted in the context of neurophysiological evidence regarding neurons in Areas MT and MSTd, and a dynamical theory of motion pattern formation (Hock, Schoner & Giese, 2003; Nichols, Hock & Schoner, 2006).
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Date Issued
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2006
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PURL
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http://purl.flvc.org/fcla/dt/13371
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Subject Headings
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Motion perception (Vision)--Mathematical models, Visual pathways, Neurophysiology, Nonlinear chemical kinetics
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Format
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Document (PDF)
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Title
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Influence of the boundaries on the acoustic scattering by a submerged target.
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Creator
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Charmes, Emmanuel., Florida Atlantic University, Beaujean, Pierre-Philippe, Cuschieri, Joseph M.
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Abstract/Description
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In shallow water or fluid half-space, the acoustic scattering from a target is significantly different from that of an unbounded medium, due to the multiple reflections occurring between the target and the boundaries. The purpose of this thesis is to investigate the influence of the boundaries on the acoustic scattering of a rigid sphere by means of a superposition method. A minimum number of point sources necessary to accurately model the scattered field is determined in the case of a free...
Show moreIn shallow water or fluid half-space, the acoustic scattering from a target is significantly different from that of an unbounded medium, due to the multiple reflections occurring between the target and the boundaries. The purpose of this thesis is to investigate the influence of the boundaries on the acoustic scattering of a rigid sphere by means of a superposition method. A minimum number of point sources necessary to accurately model the scattered field is determined in the case of a free medium, a fluid half-space and a waveguide. The free field symmetry vanishes due to the presence of boundaries and, at particular frequencies or scatterer depths, a significant change in the magnitude and spatial distribution of the scattered field occur. In an unbounded medium or fluid half space, the superposition method is shown to give similar results to analytical formulations found in the literature, provided enough point sources are used.
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Date Issued
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2005
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PURL
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http://purl.flvc.org/fcla/dt/13211
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Subject Headings
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Electromagnetic waves--Scattering, Acoustical engineering, Sound-waves--Measurement, Wave-motion, Theory of
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Format
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Document (PDF)
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Title
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The Acute Effects of Different Durations of Static Stretching on Dynamic Balance Performance.
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Creator
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Costa, Pablo Brando, Graves, B. Sue, Florida Atlantic University
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Abstract/Description
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The purpose of the study was to determine and compare the effects of different durations of stretching on balance. Female subjects (n=23) had their balance assessed before and after two stretching interventions and a control condition on three separate days, at least 48 hours apart. The quadriceps, hamstrings, and plantar flexors were stretched after a warm-up and repeated three times. In one stretching protocol, the positions were maintained for 45 seconds, while in the other stretching...
Show moreThe purpose of the study was to determine and compare the effects of different durations of stretching on balance. Female subjects (n=23) had their balance assessed before and after two stretching interventions and a control condition on three separate days, at least 48 hours apart. The quadriceps, hamstrings, and plantar flexors were stretched after a warm-up and repeated three times. In one stretching protocol, the positions were maintained for 45 seconds, while in the other stretching protocol, the positions were held for 15 seconds. The 15- second condition produced a significant improvement in the OSI scores (p < 0.05). However, repeated measures ANOVA revealed no significant differences between groups (p = 0.08). These results suggest a stretching protocol with 45-second hold durations does not adversely affect postural stability when using the current stabilometry testing procedure.
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Date Issued
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2007
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PURL
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http://purl.flvc.org/fau/fd/FA00000629
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Subject Headings
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Stretch (Physiology), Joints--Range of motion, Human locomotion, Musculoskeletal system--Physiology
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Format
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Document (PDF)
Pages