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Showing 1 to 20 of 28 for “"ship motions"”.
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Vertical ship motions in shallow water
With the increase in ship sizes, there has been an increased interest in the prediction of ship motions in shallow water, where the possibility of grounding becomes a problem. Theoretical equations governing the ship's motions have been formulated involving various hydrodynamic coefficients. In …
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Simulating ship motions in the time domain
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994.
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Nonlinear ship motions by a Rankine panel method
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1997.
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Identification of Finite-Degree-of-Freedom Models for Ship Motions
Accurate ship-motion prediction is important because it is directly related to the design, control, and economic operation of ships. Many methods are available for studying and predicting ship motions, including time-domain, strip-theory, and system-identification-based predictions. Time-domain and …
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Time domain ship motions by a three-dimensional Rankine panel method
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994.
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State-space modeling and optimal control of ship motions in a seastate
… controlled in regular and random waves. A ship at sea can experience all the translational and rotational modes of motion that are undesirable, yet unavoidable. These motions have been of great concern to the navies and other organizations engaged in shipping for decades and need to be …
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The response to ship motions of towed vehicles for use as oceanic microstructure measurement platforms
The response to ship induced motions has been predicted for four towed underwater vehicles. The purpose of the study is to determine the suitability of these vehicles for their use as oceanic microstructure sensor carrying platforms. All have been used in the past for oceanic studies, and these …
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A Time-Domain Numerical Study of Passive and Active Anti-Roll Tanks to Reduce Ship Motions
… and active anti-roll tanks and moving weights on ship motions. A point mass moving across the ship was used to model the non-linear effects of the tank systems in various computer simulation environments. PID control of the mass position was used for the active tank (pump) systems and a vibration …
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Quantifying Extreme Event Statistics for Ship Motions and Loads Using Low-Fidelity Models and Recurrent Neural Networks
Ship operators and designers alike use ship motion simulation software to predict ship responses in irregular ocean waves, along with the statistics of extreme events. Ship operators rely on precalculated polar plots during heavy seas to select speeds and headings that will protect the ship and …
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Investigating the Use of Inductive Transfer Learning and RNN to Quantify Extreme Event Statistics of Ship Motions
Ship motion software has been a critical tool for designers to study the extreme responses of ships in irregular waves. These studies and simulations often take thousands of hours to predict and analyze the ship’s motion. Simulation results are often imperative to ensure the development of accurate …
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Damage stability of ships as a safety criterion for optimisation tools
… is optimised. The damage must be relevant to ship type and applied in appropriate locations with sensible extents of damage. To fulfil this need both the Marine Accident Investigation Branch (MAIB) damage data base and a damage data base generated by Lutzen (2002) are interrogated and findings …
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Manoeuvring behaviour of ships in extreme astern seas
… robust and effective numerical tools concerning ship motions in astern seas, this thesis presents the development of a coupled non-linear 6-DOF model with frequency dependent coefficients, incorporating memory effects in random waves with a new axis system that allows straightforward combination …
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A Study on the Feasibility of Using Fractional Differential Equations for Roll Damping Models
… time tested ODEs with FDEs as applied to ship motions, specifically with an eye toward modeling different forms of roll damping. Relations between the order of differentiation a and damping coefficient b in the FDEs have been drawn for changing damping, added moment of inertia, and initial …
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Exploring Complex Problems in Fluid Dynamics: from CFD to Experiments Leveraging ML
… 1. Optimizing Vortex Generators to Reduce Ship Form Drag: In the quest for reducing ship emissions, it is imperative that the fluid mechanics of ship resistance be explored for improving propulsive efficiency. Form drag is a significant part of the resistance of high block coefficient ships …
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Optimal control theory applied to ship maneuvering in restricted waters
Ship drivers have long understood that powerful interaction forces exist when ships operate in close proximity to rigid boundaries or other vessels. Controlling the effects of these forces has been traditionally handled by experienced helmsmen. The purpose of this research is to apply modern …
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The design of a control architecture for a heavy-lift precision manipulator for use in contact with the environment
… payloads onto aircraft on the deck of a ship. The purpose of this robot is to reduce manpower requirements aboard the ship, and reduce the physical requirements for the individuals loading the payloads onto an aircraft. This particular application presents several control challenges, …
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Modeling Dynamic Ground Reaction to Predict Motion of and Loads on Stranded Ships in Waves
Ship groundings are a low probability event, but can create severe environmental and financial consequences. The objective of this thesis is to provide knowledge and understanding of the grounded ship condition to salvors and ship owners so they can reduce the possible negative consequences of …
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Analysis and Modeling of Hydrodynamic Components for Ship Roll Motion in Heavy Weather
Ship roll motion has been the subject of many studies, because of the complexities associated with this mode of ship motion, and its impact on operability, safety, and survivability. Estimation and prediction of the energy transfer and dissipation of the hydrodynamic components, added inertia and …
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Optimal control, self-tuning techniques and their application to dynamically positioned vessels
… techniques.</p> <p>In Part One, the dynamic ship positioning control problems and basic components are described. The modelling techniques of low frequency ship motions and wave motions are given. The various Kalman filtering methods are appraised. An optimal state feedback control with …
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