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Optimization Of Shape And Control Of Linear And Nonlinear Wave Energy Converters, Jiajun Song 2020 Michigan Technological University

Optimization Of Shape And Control Of Linear And Nonlinear Wave Energy Converters, Jiajun Song

Dissertations, Master's Theses and Master's Reports

In this dissertation, we address the optimal control and shape optimization of Wave Energy Converters. The wave energy converters considered in this study are the single-body heaving wave energy converters, and the two-body heaving wave energy converters. Different types of wave energy converters are modeled mathematically, and different optimal controls are developed for them. The concept of shape optimization is introduced in this dissertation; the goal is to leverage nonlinear hydrodynamic forces which are dependent on the buoy shape. In this dissertation, shape optimization is carried out and its impact on energy extraction is investigated. In all the studies conducted ...


Fundamental Design Of Submarine Communication Buoy With Oceanic Condition Considerations, Alex Resnick, Katherine Mitchell, Hannah M. Maier, Muhammad Salman 2019 Kennesaw State University

Fundamental Design Of Submarine Communication Buoy With Oceanic Condition Considerations, Alex Resnick, Katherine Mitchell, Hannah M. Maier, Muhammad Salman

Georgia Undergraduate Research Conference (GURC)

Communication with active United States Navy submarines is often difficult while the submarines are in active operation. Submarines must float close to the surface of the ocean, at a depth of less than thirty meters, to engage in heavy communication with command operations. When a submarine is on a mission; however, the submarine will operate at depths of one-hundred meters or greater, and significant communication is limited. A solution to this communication limitation includes the use of very-low or extremely-low frequency transmissions. Transfer of information is at a rate of 8 bytes/second, so only basic encrypted text can be ...


Deficiencies In The Physics Of Existing Operational Wave And Surge Models, D. T. Resio 2019 University of North Florida, Jacksonville, FL

Deficiencies In The Physics Of Existing Operational Wave And Surge Models, D. T. Resio

Ocean Waves Workshop

No abstract provided.


A New Real-Time Ocean Observing Station On Ship Shoal On Louisiana Shelf, Chunyan Li, Peter Luo, Brian Milan, Wei Huang 2019 Wave, Coastal Studies Institute, Department of Oceanography and Coastal Sciences, College of Coast and Environment, Louisiana State University, Baton Rouge, LA

A New Real-Time Ocean Observing Station On Ship Shoal On Louisiana Shelf, Chunyan Li, Peter Luo, Brian Milan, Wei Huang

Ocean Waves Workshop

One of the major challenges that we are facing in the northern Gulf of Mexico coastal area is the need of a better and reliable offshore met-ocean real time data collection system that supports the mission of Bureau of Ocean Energy Management (BOEM) and other federal and local agencies for coastal management, protection, and restoration, especially along the Louisiana coast. This area has a suite of environmental problems that require the acquisition of real time data for immediate assessment or model-based assessment and predictions that rely on this kind of data. One such system providing this kind of data is ...


Update In Us Navy Global Wave Model Forecasting, J. D. Dykes, W. E. Rogers, D. Wang 2019 Naval Research Laboratory, Stennis Space Center, MS

Update In Us Navy Global Wave Model Forecasting, J. D. Dykes, W. E. Rogers, D. Wang

Ocean Waves Workshop

No abstract provided.


Ocean Waves Workshop 2019 Session 2 Notes, Kaus Raghukumar, Sam McWilliams 2019 Integral Consulting Inc., Santa Cruz, CA

Ocean Waves Workshop 2019 Session 2 Notes, Kaus Raghukumar, Sam Mcwilliams

Ocean Waves Workshop

No abstract provided.


Directional Spectrum Measurements By The Spotter: A New Developed Wave Buoy, Kaus Raghukumar, Grace Chang, Frank Spada, Tim Jannsen 2019 Integral Consulting Inc., Santa Cruz, CA

Directional Spectrum Measurements By The Spotter: A New Developed Wave Buoy, Kaus Raghukumar, Grace Chang, Frank Spada, Tim Jannsen

Ocean Waves Workshop

The Spotter is an accurate, low-cost, easily deployable and robust solar powered wave buoy recently developed by Sofar Technologies (formerly Spoondrift). Spotter reduces costs and complexity of surface wave and current measurements, which can be useful for academic, military, and commercial research into surface wave and wave-driven dynamics. We performed a series of validation tests and research experiments with the Spoondrift Spotter. The low-cost and compact Spotter makes it easy to deploy arrays of wave buoys which was previously not feasible (or cost prohibitive) with traditional wave buoys. A well-designed array can provide a direct measurement of the directional wave ...


Innovations In Metocean Sensors, Pieter Smit, T. T. Janssen 2019 Sofar Ocean Technologies, San Francisco, CA

Innovations In Metocean Sensors, Pieter Smit, T. T. Janssen

Ocean Waves Workshop

Real-time observations are critical to understand, predict and estimate the impact of extreme weather events such as extratropical hurricanes and storms. Remote sensing, moored wave buoys and advances in predictive models have greatly advanced understanding and predictive capability of extreme ocean weather. However, due to cost and complexity of traditional moored buoys, in-situ networks are typically sparse and often close to shore and not well suited to drive predictive models over meaningful geophysical scales. Here we will discuss ongoing efforts to extend the capability of the Sofar Spotter to measure marine boundary layer dynamics. With the advancement to more portable ...


Ndbc Ocean Wave Observation System Update, Rodney Riley, Randy Stewart, Steven DiNapoli 2019 National Oceanic and Atmospheric Administration, National Data Buoy Center, Stennis Space Center, MS

Ndbc Ocean Wave Observation System Update, Rodney Riley, Randy Stewart, Steven Dinapoli

Ocean Waves Workshop

The U.S. National Oceanic and Atmospheric Administration’s (NOAA) National Data Buoy Center (NDBC) is modifying its ocean wave observation system due to parts obsolescence. The modified system is named Ocean Wave Linux (OWL). OWL will replace the NDBC’s older and now obsolete Digital Directional Wave Module (DDWM). Once OWL completes operational verification, the DDWM will be phased out of the NDBC’s operational weather buoy network.


Pressure Effect On An Ocean-Based Humidification-Dehumidification Desalination Process, Yingchen Yang 2019 The University of Texas Rio Grande Valley

Pressure Effect On An Ocean-Based Humidification-Dehumidification Desalination Process, Yingchen Yang

Mechanical Engineering Faculty Publications and Presentations

A new humidification-dehumidification (HDH) desalination process is proposed and analyzed. Being ocean based, the process does not produce any brine. It is largely powered jointly by solar energy, wind energy, and various types of ocean energies in a nearly natural way. A vacuum pump is employed to drive the air circulation throughout the HDH process. It is the only unit that consumes electricity. The HDH process is analyzed under various conditions, including using a low pressure (as low as to 0.2 atm) for humidification and the ambient pressure for dehumidification, running the entire HDH process around a low pressure ...


Dynamic Response Modeling Of High-Speed Planing Craft With Enforced Acceleration, Gene Hou, Brain Johnson, Jonathan Degroff, Steven Trenor, Jennifer Michaeli 2019 Old Dominion University

Dynamic Response Modeling Of High-Speed Planing Craft With Enforced Acceleration, Gene Hou, Brain Johnson, Jonathan Degroff, Steven Trenor, Jennifer Michaeli

Mechanical & Aerospace Engineering Faculty Publications

An approach is investigated in this study for structural dynamic analysis of a high-speed planing hull, in which the pointwise acceleration data collected from sea trials are enforced as base excitation. The paper first performed the full boat analysis of an 11-meter high speed craft for a period of one wave impact selected from each of nine seakeeping runs. The sea trial acceleration data collected from 11 accelerometers placed close to the centerline and the keel are enforced as input, while those from 3 accelerometers placed around the pilot cabin are selected for validation. The substructure dynamic analysis of the ...


Surface Kinetic Energy Distributions In The Global Oceans From A High-Resolution Numerical Model And Surface Drifter Observations, Xiaolong Yu, Aurelien Ponte, Shane Elipot, Dimitris Menemenlis, Edward Zaron, Ryan Abernathey 2019 Ifremer, Université de Brest

Surface Kinetic Energy Distributions In The Global Oceans From A High-Resolution Numerical Model And Surface Drifter Observations, Xiaolong Yu, Aurelien Ponte, Shane Elipot, Dimitris Menemenlis, Edward Zaron, Ryan Abernathey

Civil and Environmental Engineering Faculty Publications and Presentations

The surface kinetic energy of a 1/48◦ global ocean simulation and its distribution as a function of frequency and location are compared with the one estimated from 15,329 globally distributed surface drifter observations at hourly resolution. These distributions follow similar patterns with a dominant low-frequency component and well-defined tidal and near-inertial peaks globally. Quantitative differences are identified with deficits of low-frequency energy near the equator (factor 2) and at near-inertial frequencies (factor 3) and an excess of energy at semidiurnal frequencies (factor 4) for the model. Owing to its hourly resolution and its near-global spatial coverage, the array ...


Flow-Induced Oscillations In Floating Offshore Wind Turbines, Daniel Carlson 2019 University of Massachusetts Amherst

Flow-Induced Oscillations In Floating Offshore Wind Turbines, Daniel Carlson

Doctoral Dissertations

The goal of this thesis is to experimentally study the structural dynamics, wake interaction, and fluid forces on the multiple-degree of freedom systems typical of floating wind turbines. Vortex--surface alignment about flexibly-mounted prisms is studied to investigate the response of barges and semi-submersible hulls, and new results pertaining to the galloping response kink for a prism with dual inline--crossflow resonance is presented. Flow--induced oscillations of a spar model free to rotate in 3D space is replicated and observed as 2D figure--eight orbits about the center of the spar. Methods to suppress the flow from exciting the spar are proposed. The ...


Global Performance Testing, Simulation, And Optimization Of A 6-Mw Annular Floating Offshore Wind Turbine Hull, Hannah L. Allen 2019 University of Maine

Global Performance Testing, Simulation, And Optimization Of A 6-Mw Annular Floating Offshore Wind Turbine Hull, Hannah L. Allen

Electronic Theses and Dissertations

Floating offshore wind turbine (FOWT) hull technologies are evolving rapidly with many technically viable designs. However, a commercially dominant architecture has yet to emerge. This thesis presents a methodology for evaluation of the hydrodynamic performance of an annular FOWT hull. This hull shows significant promise from a manufacturing and installation standpoint, but limited performance data exists. This thesis will provide ample documentation on scale model testing of an annular FOWT hull as well as the corresponding numerical validation approach and opportunities for design improvement.

The first portion of this work involves testing a 1/100th-scale model in the Harold Alfond ...


Cavitation Number As A Function Of Disk Cavitator Radius: A Numerical Analysis Of Natural Supercavitation, Reid Prichard 2019 Liberty University

Cavitation Number As A Function Of Disk Cavitator Radius: A Numerical Analysis Of Natural Supercavitation, Reid Prichard

Senior Honors Theses

Due to the greater viscosity and density of water compared to air, the maximum speed of underwater travel is severely limited compared to other methods of transportation. However, a technology called supercavitation – which uses a disk-shaped cavitator to envelop a vehicle in a bubble of steam – promises to greatly decrease skin friction drag. While a large cavitator enables the occurrence of supercavitation at low velocities, it adds substantial unnecessary drag at higher speeds. Based on CFD results, a relationship between cavitator diameter and cavitation number is developed, and it is substituted into an existing equation relating drag coefficient to cavitation ...


A Multiline Anchor Concept For Floating Offshore Wind Turbines, Casey Fontana 2019 University of Massachusetts Amherst

A Multiline Anchor Concept For Floating Offshore Wind Turbines, Casey Fontana

Doctoral Dissertations

Floating offshore wind turbines (FOWTs) hold great potential for the renewable energy industry, but capital costs remain high. In efforts to increase FOWT substructure efficiency and reduce costs, this thesis investigates a novel multiline anchor concept in which FOWTs share anchors instead of being moored separately. The goal of this thesis is to evaluate the force dynamics, design, and potential cost reduction of the system. Anchor forces are simulated using the NREL 5 MW reference turbine and OC4-DeepCwind semisubmersible platform, and multiline anchor force is computed as the vector sum of the contributing mooring line tensions.

The use of a ...


Closed Loop Energy Maximizing Control Of A Wave Energy Converter Using An Estimated Linear Model That Approximates The Nonlinear Froude-Krylov Force, Yaqzan Mohd Yaqzan 2019 Michigan Technological University

Closed Loop Energy Maximizing Control Of A Wave Energy Converter Using An Estimated Linear Model That Approximates The Nonlinear Froude-Krylov Force, Yaqzan Mohd Yaqzan

Dissertations, Master's Theses and Master's Reports

Wave energy converters (WECs) exploit ocean wave energy and convert it into useful forms such as electricity. But for WECs to be successful on a large scale, two primary conditions need to be satisfied. The energy generated must satisfy the network requirements, and second, energy flow from waves to the grid needs to be maximized. In this dissertation, we address the second problem. Most control techniques for WECs today use the Cummins' linear model to simulate WEC hydrodynamics. However, it has been shown that under the application of a control force, where WEC motions are amplified, the linear model diverges ...


Examination Of Ice Impactor And Mold, Matt Wilson 2019 The University of Akron

Examination Of Ice Impactor And Mold, Matt Wilson

Williams Honors College, Honors Research Projects

This research project investigates impact and damage response of composite sandwich structures impacted with solid ice at extreme low-temperature. Composite sandwich structures of carbon fiber reinforced polymer sheets lining a polyvinyl chloride foam core are subjected to low-velocity impact at arctic temperatures. This impact will be delivered by a solid ice tool-tip via a drop impact testing machine. Data and test results acquired will be composed into a research report that will be submitted to The University of Akron and published in a scientific journal. This project builds upon the earlier study by Elamin, Li, & Tan (2018).


Optimization And Control Of Arrays Of Wave Energy Converters, Jianyang Lyu 2019 Michigan Technological University

Optimization And Control Of Arrays Of Wave Energy Converters, Jianyang Lyu

Dissertations, Master's Theses and Master's Reports

Wave Energy Converter Array is a practical approach to harvest ocean wave energy. To leverage the potential of the WEC array in terms of energy extraction, it is essential to have a properly designed array configuration and control system. This thesis explores the optimal configuration of Wave Energy Converters (WECs) arrays and their optimal control. The optimization of the WEC array allows both dimensions of individual WECs as well as the array layout to varying. In the first optimization problem, cylindrical buoys are assumed in the array where their radii and drafts are optimization parameters. Genetic Algorithms are used for ...


The Tides They Are A-Changin’: A Comprehensive Review Of Past And Future Nonastronomical Changes In Tides, Their Driving Mechanisms And Future Implications, Ivan D. Haigh, Mark D. Pickering, J.A. Mattias Green, Brian K. Arbic, Arne Arns, Soenke Dangendorf, David Hill, David A. Jay, multiple additional authors 2019 National Oceanography Centre Southampton, University of Southampton

The Tides They Are A-Changin’: A Comprehensive Review Of Past And Future Nonastronomical Changes In Tides, Their Driving Mechanisms And Future Implications, Ivan D. Haigh, Mark D. Pickering, J.A. Mattias Green, Brian K. Arbic, Arne Arns, Soenke Dangendorf, David Hill, David A. Jay, Multiple Additional Authors

Civil and Environmental Engineering Faculty Publications and Presentations

Scientists and engineers have observed for some time that tidal amplitudes at many locations are shifting considerably due to non-astronomical factors. Here we review comprehensively these important changes in tidal properties, many of which remain poorly understood. Over long geological time-scales, tectonic processes drive variations in basin size, depth, and shape, and hence the resonant properties of ocean basins. On shorter geological time-scales, changes in oceanic tidal properties are dominated by variations in water depth. A growing number of studies have identified widespread, sometimes regionally-coherent, positive and negative trends in tidal constituents and levels during the 19th, 20th and early ...


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