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Title: Model-based global assessment of ocean thermal energy conversion (OTEC) power potential.
Creator: Rauchenstein, Lindy, Hanson, Howard P., VanZwieten, James H., Dhanak, Manhar R., Graduate College
Date Issued: 2011-04-08
PURL: http://purl.flvc.org/fcla/dt/3170913
Subject Headings: Ocean thermal power plants, Solar energy, Continental margins
Format: Document (PDF)

Title: Design and testing of an untethered vertically ascending profiler for use in measuring near-surface turbulence.
Creator: Bogin, Jeffrey Isaac., Florida Atlantic University, Dhanak, Manhar R.
Abstract/Description: The Vertically Ascending Micro-scale Profiler, or VAMP, has been designed, constructed, and tested to be used in conjunction with FAU's Turbulence Package in order to collect vertical turbulence profiles close to the free surface. Unique to VAMP is that it has been specifically designed as an untethered ascending profiler. Examination of turbulence data collected using VAMP shows that the measured shear spectrum and the turbulent kinetic energy dissipation closely matches the Nasmyth Spectrum...
Show moreThe Vertically Ascending Micro-scale Profiler, or VAMP, has been designed, constructed, and tested to be used in conjunction with FAU's Turbulence Package in order to collect vertical turbulence profiles close to the free surface. Unique to VAMP is that it has been specifically designed as an untethered ascending profiler. Examination of turbulence data collected using VAMP shows that the measured shear spectrum and the turbulent kinetic energy dissipation closely matches the Nasmyth Spectrum. Data processing techniques made it possible to filter out motion generated by surface wave action, which allowed VAMP to collect data at depths as shallow as the troughs of the surface waves. VAMP can be launched, deployed several times, and recovered all within a thirty minute time frame by a crew of four.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13020
Subject Headings: Turbulence--Measurement, Surface waves (Oceanography)
Format: Document (PDF)

Title: Experimental Investigation of Skin Friction Drag Reduction on a Flat Plate using Microbubbles.
Creator: Grabe, Zachary A., Dhanak, Manhar R., Florida Atlantic University
Abstract/Description: A microbubble generation system has been designed, constructed, and tested in a circulating water tunnel. A 1.0 m long flat plate was subjected to a flow where the Reynolds number ranged from ReL = 7.23x 10^5 - 1.04 x 10^6. Bubble diameters and skin friction measurements were studied at various airflow rates and water velocities. Bubbles were produced by forcing air through porous plates that were mounted flush with the bottom of the test plate. Once emitted through the plates, the bubbles...
Show moreA microbubble generation system has been designed, constructed, and tested in a circulating water tunnel. A 1.0 m long flat plate was subjected to a flow where the Reynolds number ranged from ReL = 7.23x 10^5 - 1.04 x 10^6. Bubble diameters and skin friction measurements were studied at various airflow rates and water velocities. Bubbles were produced by forcing air through porous plates that were mounted flush with the bottom of the test plate. Once emitted through the plates, the bubbles traveled downstream in the boundary layer. The airflow rate and water velocity were found to have the most significant impact on the size of the bubbles created. Skin friction drag measurements were recorded in detail in the velocity and airflow rate ranges. The coefficient of skin friction was determined and relationships were then established between this coefficient and the void ratio.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00012523
Subject Headings: Frictional resistance (Hydrodynamics), Drag (Aerodynamics), Skin friction (Aerodynamics), Fluid mechanics
Format: Document (PDF)

Title: An experimental investigation of the performance of a series of propellers for a human powered underwater vehicle.
Creator: Heeb, Karl Von., Florida Atlantic University, Dhanak, Manhar R.
Abstract/Description: Designing a propeller for optimum performance on a human powered underwater vehicle presents a significant engineering challenge. The propeller must be highly efficient to utilize the inherently low power output of a human. Also, the propeller must be correctly matched to the maximum sustainable torque of the propulsor. This thesis experimentally investigates a minimum induced loss propeller design program and its application to a human powered underwater vehicle. The design program is based...
Show moreDesigning a propeller for optimum performance on a human powered underwater vehicle presents a significant engineering challenge. The propeller must be highly efficient to utilize the inherently low power output of a human. Also, the propeller must be correctly matched to the maximum sustainable torque of the propulsor. This thesis experimentally investigates a minimum induced loss propeller design program and its application to a human powered underwater vehicle. The design program is based on the vortex theory of propellers. The work includes experimental measurements of the velocity and rotational rate of three propellers designed with the minimum induced loss propeller design program. This positively verifies the output of the design algorithm. Also, the research, through the use of an underwater ergometer, determines the maximum power and torque sustainable by a human pedaling underwater. Final results of the research show that the design algorithm overestimates the blade section angles by 25% because the design program neglects the influence of the wake of the vehicle.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/15078
Subject Headings: Propellers, Submersibles, Underwater propulsion
Format: Document (PDF)

Title: Subsurface flow generated by a steady wind stress applied at the water surface.
Creator: Gurfinkiel, Lionel., Florida Atlantic University, Dhanak, Manhar R.
Abstract/Description: A turbulent water current induced by winds, through a friction force at the sea surface and subjected to the Coriolis force in shallow water was studied. A Large Eddy Simulation model developed by Zikanov et al. is used to solve the Navier-Stokes equations. To define the bottom boundary condition, a drag coefficient parameter, based on the ideas of Csanady, is used to evaluate the shear stress at the bottom. To find a suitable bottom boundary condition for this LES simulation, several cases...
Show moreA turbulent water current induced by winds, through a friction force at the sea surface and subjected to the Coriolis force in shallow water was studied. A Large Eddy Simulation model developed by Zikanov et al. is used to solve the Navier-Stokes equations. To define the bottom boundary condition, a drag coefficient parameter, based on the ideas of Csanady, is used to evaluate the shear stress at the bottom. To find a suitable bottom boundary condition for this LES simulation, several cases were considered with change in drag coefficient property. The effect of variation in the depth of the water column was also considered. Variation in surface deflection of the current, variation of the mass flux and distribution of eddy viscosity with depth of the water column are determined. The cases are compared with the case of a deep water column. Numerical results are also compared with field observations.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13030
Subject Headings: Ocean-atmosphere interaction--Mathematical models, Turbulence, Wind waves--Mathematical models
Format: Document (PDF)

Title: Sound generated due to vortical flow past a forward facing step.
Creator: Gundlapalli, Ravishankar., Florida Atlantic University, Dhanak, Manhar R.
Abstract/Description: The sound field associated with the motion of 2-dimensional finite core vortex past a forward facing step is obtained. A numerical scheme using Contour Dynamics technique and incompressible, inviscid equations of motion is developed to determine the evolution of the structure of the vortex, its path over the step and the radiated sound. An appropriate low-frequency Green's function is derived and the expression for the far field acoustic pressure as formulated by Mohring is used. The vortex...
Show moreThe sound field associated with the motion of 2-dimensional finite core vortex past a forward facing step is obtained. A numerical scheme using Contour Dynamics technique and incompressible, inviscid equations of motion is developed to determine the evolution of the structure of the vortex, its path over the step and the radiated sound. An appropriate low-frequency Green's function is derived and the expression for the far field acoustic pressure as formulated by Mohring is used. The vortex structure evolves in the non-uniform flow in the vicinity of the step and under certain conditions is found to undergo significant deformation of its core structure. The far field acoustic pressure is found to be a strong function of vortex motion in the vicinity of the step. Results for the vortex trajectory and the associated acoustic pressure are presented for a variety of flow parameters.
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Date Issued: 1992
PURL: http://purl.flvc.org/fau/fd/FADT14825
Subject Headings: Underwater acoustics, Vortex-motion, Eddies, Hydrodynamics
Format: Document (PDF)

Title: Thermocline tracking using an upgraded ocean explorer autonomous underwater vehicle.
Creator: Clabon, Mathieu., Florida Atlantic University, Dhanak, Manhar R.
Abstract/Description: This thesis addresses the problem of tracking a thermocline---a layer of water showing an intense vertical temperature gradient---with an Autonomous Underwater Vehicle (AUV). One of Florida Atlantic University's Ocean Explorer (OEX) AUV has been upgraded, as part of the work described here, by integration of a standard and convenient software interface, and used in several thermocline survey experiments aimed at gathering oceanographic data relevant to thermoclines. A tool that simulates the...
Show moreThis thesis addresses the problem of tracking a thermocline---a layer of water showing an intense vertical temperature gradient---with an Autonomous Underwater Vehicle (AUV). One of Florida Atlantic University's Ocean Explorer (OEX) AUV has been upgraded, as part of the work described here, by integration of a standard and convenient software interface, and used in several thermocline survey experiments aimed at gathering oceanographic data relevant to thermoclines. A tool that simulates the longitudinal motion of the OEX through a water slice, whose temperature map is read using a simulated temperature and depth sensor, has been developed. Using this tool and information from at-sea experiments, several control methods for the OEX to track a thermocline were analyzed. In particular, two different algorithms were implemented and tested by simulation. Overall, two control algorithms have been validated, and it will soon be possible to provide the AUV with a thermocline tracking capability.
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Date Issued: 2003
PURL: http://purl.flvc.org/fcla/dt/13025
Subject Headings: Thermoclines (Oceanography), Oceanographic submersibles--Computer simulation, Underwater navigation
Format: Document (PDF)

Title: Simulations and feedback control of nonlinear coupled electromechanical oscillators for energy conversion applications.
Creator: Psarrou, Dimitrios., Dhanak, Manhar R., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis discusses the coupling of a mechanical and electrical oscillator, an arrangement that is often encountered in mechatronics actuators and sensors. The dynamics of this coupled system is mathematically modeled and a low pass equivalent model is presented. Numerical simulations are then performed, for various input signals to characterize the nonlinear relationship between the electrical current and the displacement of the mass. Lastly a framework is proposed to estimate the mass...
Show moreThis thesis discusses the coupling of a mechanical and electrical oscillator, an arrangement that is often encountered in mechatronics actuators and sensors. The dynamics of this coupled system is mathematically modeled and a low pass equivalent model is presented. Numerical simulations are then performed, for various input signals to characterize the nonlinear relationship between the electrical current and the displacement of the mass. Lastly a framework is proposed to estimate the mass position without the use of a position sensor, enabling the sensorless control of the coupled system and additionally providing the ability for the system to act as an actuator or a sensor. This is of value for health monitoring, diagnostics and prognostics, actuation and power transfer of a number of interconnected machines that have more than one electrical system, driving corresponding mechanical subsystems while being driven by the same voltage source and at the same time being spectrally separated and independent.
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Date Issued: 2011
PURL: http://purl.flvc.org/FAU/3320109
Subject Headings: Renewable energy sources, Mechatronics, Nonlinear theories, Oscillators, System analysis
Format: Document (PDF)

Title: Automated Launch and Recovery of an Autonomous Underwater Vehicle from an Unmanned Surface Vessel.
Creator: Sarda, Edoardo I, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Research on collaboration among unmanned platforms is essential to improve the applications for autonomous missions, by expanding the working environment of the robotic systems, and reducing the risks and the costs associated with conducting manned operations. This research is devoted to enable the collaboration between an Unmanned Surface Vehicle (USV) and an Autonomous Underwater Vehicle (AUV), by allowing the first one to launch and recover the second one. The objective of this...
Show moreResearch on collaboration among unmanned platforms is essential to improve the applications for autonomous missions, by expanding the working environment of the robotic systems, and reducing the risks and the costs associated with conducting manned operations. This research is devoted to enable the collaboration between an Unmanned Surface Vehicle (USV) and an Autonomous Underwater Vehicle (AUV), by allowing the first one to launch and recover the second one. The objective of this dissertation is to identify possible methods to launch and recover a REMUS 100 AUV from a WAM-V 16 USV, thus developing this capability by designing and implementing a launch and recovery system (LARS). To meet this objective, a series of preliminary experiments was first performed to identify two distinct methods to launch and recover the AUV: mobile and semi-stationary. Both methods have been simulated using the Orcaflex software. Subsequently, the necessary control systems to create the mandatory USV autonomy for the purpose of launch and recovery were developed. Specifically, a series of low-level controllers were designed and implemented to enable two autonomous maneuvers on the USV: station-keeping and speed & heading control. In addition, a level of intelligence to autonomously identify the optimal operating conditions within the vehicles' working environment, was derived and integrated on the USV. Lastly, a LARS was designed and implemented on the vehicles to perform the operation following the proposed methodology. The LARS and all subsystems developed for this research were extensively tested through sea-trials. The methodology for launch and recovery, the design of the LARS and the experimental findings are reported in this document.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004631, http://purl.flvc.org/fau/fd/FA00004631
Subject Headings: Underwater acoustic telemetry., Fuzzy systems., Nonlinear control theory., Adaptive signal processing., Oceanographic submersibles--Automatic control., Submersibles--Control systems.
Format: Document (PDF)

Title: A Low-Level USV Controller Incorporating an Environmental Disturbance Observer.
Creator: Diddams, Michael Albert, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Modeling, system identification and controller design for a 16’ catamaran is described with the objective of enhanced operation in the presence of environmental disturbances including wind, waves and current. The vehicle is fully-actuated in surge, sway and yaw degrees of freedom. Analytical and experimental system identification is carried out to create a numerical model of the vehicle. A composite system of a Multiinput multi-output Proportional-Derivative (PD) controller and a nonlinear...
Show moreModeling, system identification and controller design for a 16’ catamaran is described with the objective of enhanced operation in the presence of environmental disturbances including wind, waves and current. The vehicle is fully-actuated in surge, sway and yaw degrees of freedom. Analytical and experimental system identification is carried out to create a numerical model of the vehicle. A composite system of a Multiinput multi-output Proportional-Derivative (PD) controller and a nonlinear disturbance observer is used for station-keeping and transiting modes of operation. A waypoint transiting algorithm is developed to output heading and cross-track error from vehicle position and waypoints. A control allocation method is designed to lower azimuthing frequency and incorporate angle saturation and rate limits. Validation is achieved with improvement in simulation with the addition of the nonlinear observer.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013022
Subject Headings: Unmanned surface vehicles, Environmental disturbances, Catamarans--Design and construction
Format: Document (PDF)

Title: Characterization of Internal Wave Activity in the Straits of Florida.
Creator: Tarantul Soto, Andrew, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The Gulf Stream current in the Straits is typically dominated by a strong northerly current, associated shear, and eddies. The water column also includes a prominent thermocline and periodically features internal waves centered on the upper or lower edges of the thermocline. Despite numerous previous related studies, there is limited available field data on internal waves in the Straits of Florida. Here, study and analysis of velocity, temperature and conductivity data acquired in the Straits...
Show moreThe Gulf Stream current in the Straits is typically dominated by a strong northerly current, associated shear, and eddies. The water column also includes a prominent thermocline and periodically features internal waves centered on the upper or lower edges of the thermocline. Despite numerous previous related studies, there is limited available field data on internal waves in the Straits of Florida. Here, study and analysis of velocity, temperature and conductivity data acquired in the Straits over a period of time are described, in support of identifying presence of internal waves in the flow. A systematic procedure is employed in modifying the universal Garrett- Munk spectrum for internal waves in the open ocean for application to flow in the Straits of Florida. Using this process, identified internal waves are characterized and related velocity fluctuations in the time series are isolated to facilitate consideration of their correlations with simultaneously observed magnetic fields.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00005946
Subject Headings: Dissertations, Academic -- Florida Atlantic University, Florida, Straits of, Gulf Stream (Fla.), Internal waves.
Format: Document (PDF)

Title: Electromagnetic field emissions from underwater power cables.
Creator: DiBiasio, Christopher, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This study is performed as a partial aid to a larger study that aims to determine if electromagnetic fields produced by underwater power cables have any effect on marine species. In this study, a new numerical method for calculating magnetic fields around subsea power cables is presented and tested. The numerical method is derived from electromagnetic theory, and the program, Matlab, is implemented in order to run the simulations. The Matlab code is validated by performing a series of tests...
Show moreThis study is performed as a partial aid to a larger study that aims to determine if electromagnetic fields produced by underwater power cables have any effect on marine species. In this study, a new numerical method for calculating magnetic fields around subsea power cables is presented and tested. The numerical method is derived from electromagnetic theory, and the program, Matlab, is implemented in order to run the simulations. The Matlab code is validated by performing a series of tests in which the theoretical code is compared with other previously validated magnetic field solvers. Three main tests are carried out; two of these tests are physical and involve the use of a magnetometer, and the third is numerical and compares the code with another numerical model known as Ansys. The data produced by the Matlab code remains consistent with the measured values from both the magnetometer and the Ansys program; thus, the code is considered valid. The validated Matlab code can then be implemented into other parts of the study in order to plot the magnetic field around a specific power cable.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004277, http://purl.flvc.org/fau/fd/FA00004277
Subject Headings: DIstributed generation of electric power, Electromagnetic interference, Electromagnetic theory, Ocean energy resources -- Environmental aspects
Format: Document (PDF)

Title: A Deep Learning Approach To Target Recognition In Side-Scan Sonar Imagery.
Creator: Einsidler, Dylan, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Automatic target recognition capabilities in autonomous underwater vehicles has been a daunting task, largely due to the noisy nature of sonar imagery and due to the lack of publicly available sonar data. Machine learning techniques have made great strides in tackling this feat, although not much research has been done regarding deep learning techniques for side-scan sonar imagery. Here, a state-of-the-art deep learning object detection method is adapted for side-scan sonar imagery, with...
Show moreAutomatic target recognition capabilities in autonomous underwater vehicles has been a daunting task, largely due to the noisy nature of sonar imagery and due to the lack of publicly available sonar data. Machine learning techniques have made great strides in tackling this feat, although not much research has been done regarding deep learning techniques for side-scan sonar imagery. Here, a state-of-the-art deep learning object detection method is adapted for side-scan sonar imagery, with results supporting a simple yet robust method to detect objects/anomalies along the seabed. A systematic procedure was employed in transfer learning a pre-trained convolutional neural network in order to learn the pixel-intensity based features of seafloor anomalies in sonar images. Using this process, newly trained convolutional neural network models were produced using relatively small training datasets and tested to show reasonably accurate anomaly detection and classification with little to no false alarms.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013025
Subject Headings: Deep learning, Sidescan sonar, Underwater vision
Format: Document (PDF)

Title: caHydrodynamic analysis of flapping foils for the propulsion of near surface under water vehicles using the panel method.
Creator: Bustos, Julia, Ananthakrishnan, Palaniswamy, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis presents two-dimensional hydrodynamic analysis of flapping foils for the propulsion of underwater vehicles using a source-vortex panel. Using a simulation program developed in MatLab, the hydrodynamic forces (such as the lift and the drag) as well as the propulsion thrust and efficiency are computed with this method. The assumptions made in the analysis are that the flow around a hydrofoil is two-dimensional, incompressible and inviscid. The analysis is first considered for the...
Show moreThis thesis presents two-dimensional hydrodynamic analysis of flapping foils for the propulsion of underwater vehicles using a source-vortex panel. Using a simulation program developed in MatLab, the hydrodynamic forces (such as the lift and the drag) as well as the propulsion thrust and efficiency are computed with this method. The assumptions made in the analysis are that the flow around a hydrofoil is two-dimensional, incompressible and inviscid. The analysis is first considered for the case of a deeply submerged hydrofoil followed by the case where it is located in shallow water depth or near the free surface. In the second case, the presence of the free surface and wave effects are taken into account, specifically at high and low frequencies and small and large amplitudes of flapping. The objective is to determine the thrust and efficiency of the flapping –foils under the influence of added effects of the free surface. Results show that the free-surface can significantly affect the foil performance by increasing the efficiency particularly at high Frequencies.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004351, http://purl.flvc.org/fau/fd/FA00004351
Subject Headings: Aerodynamics -- Mathematical models, Fluid mechanics, Naval architecture, Ships -- Aerodynamics, Steering gear
Format: Document (PDF)

Title: Wave Ship Interaction in Transforming Seas.
Creator: Gong, Fuxian, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: In near-shore transforming seas, as waves approach the shoreline, wave shoaling and sometimes wave breaking take place due to the decreasing water depth. When a ship advances through the transforming seas, the ship body and waves interact with each other substantially and can lead to unknown motions of the ship hull. The physical process of how the wave transforms in the surf zone and how the vehicle actually behaves when it passes through the transforming seas is a complicated issue that...
Show moreIn near-shore transforming seas, as waves approach the shoreline, wave shoaling and sometimes wave breaking take place due to the decreasing water depth. When a ship advances through the transforming seas, the ship body and waves interact with each other substantially and can lead to unknown motions of the ship hull. The physical process of how the wave transforms in the surf zone and how the vehicle actually behaves when it passes through the transforming seas is a complicated issue that triggers considerable research interest. The goal of my research is to characterize the dynamics of a high-speed surface ship model in transforming seas through a parametric numerical study of the shipwave interactions. In this study, the vehicle of interest is a surface effect ship (SES) and we aim to contribute to developing a methodology for simulating the transforming wave environment, including wave breaking, and its interactions with the SES. The thesis work uses a commercial software package ANSYS Fluent to generate numerical waves and model the interface between water and air using the volume of fluid (VoF) method. A ship motion solver and the dynamic mesh are used to enable the modeled ship to perform three degree-of-freedom (DoF) motion and the near-region of the ship hull to deform as well as re-mesh. Non-conformal meshes with hybrid compositions of different cell types and various grid sizes are used in the simulations for different purposes. Five user-defined functions (UDFs) are dynamically linked with the flow solver to incorporates ship/grid motions, wave damping and output of the numerical results. A series of steps were taken sequentially: 1) validation for ship motions including simulation of a static Wigley hull under steady flows to compare against previous experimental results by other researchers, and the comparison between the static SES model under steady flows and the moving SES model advancing in the calm water; 2) study of the ship with 3 DoF advancing in calm water of both constant depth and varying depth; 3) validation for numerical waves, including predictions of numerically progressive waves in both a regular tank and a tank with a sloped fringing reef to compare with theoretical and experimental results, respectively; 4) investigation of the transforming characteristics of the wave traveling over the sloped fringing reef, which mimics the near-shore wave environment and a study of the dynamics of the SES through transforming waves. We find that the flow solver used in this study reliably models the wave profiles along the ship hull. The comparison between a static SES in a current and a moving SES in calm water at the same Froude number shows that although the velocity fields around the vehicle are significantly different, the wave profiles inside and outside the rigid cushion of the vehicle are similar and the resistance force experienced by the vehicle in the two scenarios agree well over time. We conducted five numerical simulations of the vehicle traveling from shallow water to deep water across the transition zone for different Froude numbers. From the results, we find that as the Froude number increases, the wave resistance force on the vehicle becomes larger in both shallow water and deep water. In addition, the overall mean resistance force experienced by the vehicle over the whole trip increases with the Froude number. Statistical analysis of the wave motions suggests that the energy flux decreases dramatically in the onshore direction as the waves break. The more severe the wave-breaking process, the greater the decrease in energy flux. Both the increase of Froude number and the wave steepness apparently increase the resistance force on the vehicle in the shallow water. This thesis work captures the impact of the transforming characteristics of the waves and closely replicates the behavior of how waves interact with a ship in transforming seas through numerical modeling and simulation.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00004916, http://purl.flvc.org/fau/fd/FA00004916
Subject Headings: Hydrodynamics--Mathematical models., Fluid dynamics--Mathematical models., Ocean waves--Measurement., Water waves--Measurement., Coastal engineering.
Format: Document (PDF)

Title: Stereo vision-based target tracking system for USV operations.
Creator: Sinisterra, Armando Jose, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A methodology to estimate the state of a moving marine vehicle, defined by its position, velocity and heading, from an unmanned surface vehicle (USV), also in motion, using a stereo vision-based system, is presented in this work, in support of following a target vehicle using an USV.
Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004466, http://purl.flvc.org/fau/fd/FA00004466
Subject Headings: Adaptive control systems, Adaptive signal processing, Computer vision, Inertial navigation systems, Intelligent control systems, Motion segmentaton, Oceanographic instruments -- Development, Ubiquitous computing
Format: Document (PDF)

Title: Real-Time Localization of a Magnetic Anomaly: A Study of the Effectiveness of a Genetic Algorithm for Implementation on an Autonomous Underwater Vehicle.
Creator: Philippeaux, Harryel Arsene, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The primary objective of this research is to investigate the viability of magnetic anomaly localization with an autonomous underwater vehicle, using a genetic algorithm (GA). The localization method, first proposed by Sheinker. et al. 2008, is optimized here for the case of a moving platform. Extensive magnetic field modeling and algorithm simulation has been conducted and yields promising results. Field testing of the method is conducted with the use of the Ocean Floor Geophysics Self...
Show moreThe primary objective of this research is to investigate the viability of magnetic anomaly localization with an autonomous underwater vehicle, using a genetic algorithm (GA). The localization method, first proposed by Sheinker. et al. 2008, is optimized here for the case of a moving platform. Extensive magnetic field modeling and algorithm simulation has been conducted and yields promising results. Field testing of the method is conducted with the use of the Ocean Floor Geophysics Self-Compensating Magnetometer (SCM). Extensive out-of-water field testing is conducted to validate the ability to measure a target signal in a uniform NED frame as well as to validate the effectiveness of the GA. The outcome of the simulation closely matches the results of the conducted field tests. Additionally, the SCM is fully integrated with FAU’s Remus 100 AUV and preliminary in-water testing of the system has been conducted.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00005948
Subject Headings: Dissertations, Academic -- Florida Atlantic University, Autonomous underwater vehicles, Genetic algorithms., Geomagnetic field, Geomagnetism.
Format: Document (PDF)

Title: Optical 2D Positional Estimation for a Biomimetic Station-Keeping Autonomous Underwater Vehicle.
Creator: Nunes, Christopher, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Underwater vehicles often use acoustics or dead reckoning for global positioning, which is impractical for low cost, high proximity applications. An optical based positional feedback system for a wave tank operated biomimetic station-keeping vehicle was made using an extended Kalman filter and a model of a nearby light source. After physical light model verification, the filter estimated surge, sway, and heading with 6 irradiance sensors and a low cost inertial measurement unit (~$15)....
Show moreUnderwater vehicles often use acoustics or dead reckoning for global positioning, which is impractical for low cost, high proximity applications. An optical based positional feedback system for a wave tank operated biomimetic station-keeping vehicle was made using an extended Kalman filter and a model of a nearby light source. After physical light model verification, the filter estimated surge, sway, and heading with 6 irradiance sensors and a low cost inertial measurement unit (~$15). Physical testing with video feedback suggests an average error of ~2cm in surge and sway, and ~3deg in yaw, over a 1200 cm2 operational area. This is 2-3 times better, and more consistent, than adaptations of prior art tested alongside the extended Kalman filter feedback system. The physical performance of the biomimetic platform was also tested. It has a repeatable forward velocity response with a max of 0.3 m/s and fair stability in surface testing conditions.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004528, http://purl.flvc.org/fau/fd/FA00004528
Subject Headings: Biometric identification, Feedback control systems, Oceanographic submersibles -- Design and construction, Optical pattern recognition, Remote submersibles -- Design and construction
Format: Document (PDF)

Title: Performance Enhancement of an ACV in Varying Water Depth.
Creator: Kouvaras, Nicholas, Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This research focuses on the study of the behavior of a high speed vehicle and particularly an air-cushion vehicle (ACV) in varying bathymetry. An extensive data acquisition system is developed to gather data during the experiments. Four groups of experiments are conducted in a wave tank using a scale model surface effect ship to generate a database that is post processed to assess phenomena under various conditions. Group No1 experiments involved characterizing the wave motion in the tank in...
Show moreThis research focuses on the study of the behavior of a high speed vehicle and particularly an air-cushion vehicle (ACV) in varying bathymetry. An extensive data acquisition system is developed to gather data during the experiments. Four groups of experiments are conducted in a wave tank using a scale model surface effect ship to generate a database that is post processed to assess phenomena under various conditions. Group No1 experiments involved characterizing the wave motion in the tank in the absence of the vehicle as the waves transformed in response to variation in water depth. Based on these experimental datasets, the wave breaking type and position are predicted using a machine learning approach and, more specifically, a neural network of the multilayer perceptron type. Group No2 experiments are in support of a parametric study to evaluate the vehicle's performance under calm water conditions when the control inputs are varied. A system identific ation approach based on the experimental data is proposed to create a model that predicts the vehicles translational motion. In group No3 the experiments involve the vehicle travelling with a non-zero forward speed and encountering transforming head and following seas. Transient and non-linear phenomena and relations among parameters are observed Group No 4 experiments involve the vehicle maintaining a position in the "surf-zone" under manual control, encountering breaking waves that break on its bow skirt. Non-linear phenomena are discussed based on the experimental results.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004514, http://purl.flvc.org/fau/fd/FA00004514
Subject Headings: Wave motlion, Theory of., Water waves--Measurement., Ground-effect machines.
Format: Document (PDF)

Title: Boundary Layer Control on a Circular Cylindrical Body through Oscillating Lorentz Forcing.
Creator: Seltzer, Ryan K., Dhanak, Manhar R., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Boundary layer control on a circular cylindrical body through oscillating Lorentz forcing is studied by means of numerical simulation of the vorticity-stream function formulation of the Navier-Stokes equations. The model problem considers axisymmetric seawater flow along an infinite cylinder controlled by an idealized radially directed Lorentz force oscillating spatially and temporally. Under optimum forcing parameters, it is shown that sustainable Lorentz induced vortex rings can travel...
Show moreBoundary layer control on a circular cylindrical body through oscillating Lorentz forcing is studied by means of numerical simulation of the vorticity-stream function formulation of the Navier-Stokes equations. The model problem considers axisymmetric seawater flow along an infinite cylinder controlled by an idealized radially directed Lorentz force oscillating spatially and temporally. Under optimum forcing parameters, it is shown that sustainable Lorentz induced vortex rings can travel along the cylinder at a speed equivalent to the phase speed of forcing . Wall stress is shown to locally change sign in the region adjacent to the vortex, considerably decreasing net viscous drag . Adverse flow behaviors are revealed as a result of studying the effects of the Reynolds numbers, strength of the Lorentz force, and phase speed of forcing for boundary layer control. Adverse flow behaviors inc I ude complex vortex configurations found for suboptimal forcing resulting in a considerable increase in wall stress.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00012549
Subject Headings: Mathematical physics, Lorentz transformations, Boundary layer control, Fluid dynamics
Format: Document (PDF)

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