Ocean Engineering Commons^™

Parametric Investigation Of A Laboratory Drop Test To Simulate Base Acceleration Induced By Wave Impacts Of High Speed Planing Craft, John D. Barber

Mechanical & Aerospace Engineering Theses & Dissertations

High speed operations in a small craft can be physically punishing and, in some circumstances, even dangerous for the crew. The aspect of small craft operations that make them punishing for the crew is wave slamming generated by wave impacts as the craft is traveling over the seas at high speed.

The initial step of this thesis effort was to perform a literature survey to determine what knowledge existed within the technical and academic community about wave slamming and simulating them with drop tests.

Eventually, a final experiment strongly influenced by the experiment model found in (Protocol 1, 2014) was …

Constrained Discrete Phase Control Of A Heaving Wave Energy Converter In Irregular Seas Using Reinforcement Learning, Praveen D. Malali

Mechanical & Aerospace Engineering Theses & Dissertations

Designed for offshore deployment in irregular seas, the point absorber wave energy conversion (WEC) system is promisingly attractive amongst the currently available WEC technologies. The effectiveness of phase control when applied to a heaving point absorber through a hydraulic power take-off (PTO) system is systematically investigated in both regular and irregular waves. For this purpose, two phase control accumulators are utilized in the hydraulic PTO system. Simulations are performed in MATLAB® using the Cummins equation to model the dynamics of the heaving point absorber in the time domain.

For a given sea state, the opening instant of the control valves …

Methodology To Quantify Vertical Accelerations Of Planing Craft In Irregular Waves, Jennifer Suzanne Grimsley

Mechanical & Aerospace Engineering Theses & Dissertations

Planing craft operating in waves at high speeds can experience high, repetitive vertical accelerations that are random and nonlinear in relation to the sea condition. A proper understanding of vertical accelerations is critical to meet statistically based criteria for structural design, habitability, and equipment selection. Historically, it was assumed that planing craft vertical accelerations fit the Exponential distribution, and design methods adopted this conclusion. However, several published papers have raised doubts regarding the accuracy and validity of this Exponential distribution assumption.

The statistical behavior of planing craft vertical accelerations are examined for the Parent and Peak data sets from twenty-eight …

Passive And Active Nonlinear Control Of Ship Roll Motions Using U-Tube Tanks, Thongchai Phairoh

Mechanical & Aerospace Engineering Theses & Dissertations

A U-tube water tank is first designed to roll a ship floating on still water. The 6-degree of freedom (DOF) dynamic model of U-tube tank is derived and the effects of its parameters on ship roll motion are studied. Numerical simulations show that the U-tube tank is an effective stimulator to roll the ship on still water. For a rolling ship, the U-tube tank can be used as a damper to reduce ship roll motion quickly.

Active control of ship roll motion with a proportional and derivative (PD) controller, linear quadratic regulator (LQR), generalized predictive control (GPC), and deadbeat predictive …

Generalized Predictive Control Of Ship Coupling Motions Using Active Flume Tanks, Abdulkarim Mohammed Alotaiwi

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation uses the Generalized Predictive Control (GPC) approach to design a control system for a ship rolling motion coupled with the sway and yaw using an activated flume tank. GPC is a strategy based on system output prediction over finite horizon known as the prediction horizon. GPC controller is designed from the coefficients of the Autoregressive model with exogenous input (ARX) that are computed directly from input and output data. It computes the future control input based on the cost function with weighted input and output. System identification approach is implemented on the system to find the ARX coefficients …

Optimal Feedback Control For Ship Roll Motion Under Sea States, Anusit Anmanatarkul

Mechanical & Aerospace Engineering Theses & Dissertations

The primary influences of ship motion are roll motion. The purpose of this dissertation is to discuss a means to reduce the roll amplitude of ship motion in the case of zero forward speed using the roll mitigation device known as the flume tank, or U-tube, tank. Passive control and active control are studied. Optimal feedback control is the designated algorithm for activated roll mitigation device. The assumed model in this study is a submarine chaser. The linear coupled equation of swaying, rolling, and yawing motion of this assumed model is studied. The roll motion of this vessel is investigated …