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Full-Text Articles in Engineering
Free-Decay Heave Motion Of A Spherical Buoy, Jacob K. Colling, Saeed Jafari Kang, Esmaeil Dehdashti, Salman Husain, Hassan Masoud, Gordon Parker
Free-Decay Heave Motion Of A Spherical Buoy, Jacob K. Colling, Saeed Jafari Kang, Esmaeil Dehdashti, Salman Husain, Hassan Masoud, Gordon Parker
Michigan Tech Publications
We examined the heave motion of a spherical buoy during a free-decay drop test. A comprehensive approach was adopted to study the oscillations of the buoy involving experimental measurements and complementary numerical simulations. The experiments were performed in a wave tank equipped with an array of high-speed motion-capture cameras and a set of high-precision wave gauges. The simulations included three sets of calculations with varying levels of sophistication. Specifically, in one set, the volume-of-fluid (VOF) method was used to solve the incompressible, two-phase, Navier–Stokes equations on an overset grid, whereas the calculations in other sets were based on Cummins and …
A Hamiltonian Surface-Shaping Approach For Control System Analysis And The Design Of Nonlinear Wave Energy Converters, Shadi Darani, Ossama Abdelkhalik, Rush D. Robinett Iii, David Wilson
A Hamiltonian Surface-Shaping Approach For Control System Analysis And The Design Of Nonlinear Wave Energy Converters, Shadi Darani, Ossama Abdelkhalik, Rush D. Robinett Iii, David Wilson
Department of Mechanical and Aerospace Engineering Publications
The dynamic model of Wave Energy Converters (WECs) may have nonlinearities due to several reasons such as a nonuniform buoy shape and/or nonlinear power takeoff units. This paper presents the Hamiltonian Surface-Shaping (HSS) approach as a tool for the analysis and design of nonlinear control of WECs. The Hamiltonian represents the stored energy in the system and can be constructed as a function of the WEC’s system states, its position, and velocity. The Hamiltonian surface is defined by the energy storage, while the system trajectories are constrained to this surface and determined by the power flows of the applied non-conservative …
Control Of Wave Energy Converters With Discrete Displacement Hydraulic Power Take-Off Units, Shangyan Zou, Ossama Abdelkhalik
Control Of Wave Energy Converters With Discrete Displacement Hydraulic Power Take-Off Units, Shangyan Zou, Ossama Abdelkhalik
Michigan Tech Publications
The control of ocean Wave Energy Converters (WECs) impacts the harvested energy. Several control methods have been developed over the past few decades to maximize the harvested energy. Many of these methods were developed based on an unconstrained dynamic model assuming an ideal power take-off (PTO) unit. This study presents numerical tests and comparisons of a few recently developed control methods. The testing is conducted using a numerical simulator that simulates a hydraulic PTO. The PTO imposes constraints on the maximum attainable control force and maximum stroke. In addition, the PTO has its own dynamics, which may impact the performance …
Focus Energy Determination Of Mining Microseisms Using Residual Seismic Wave Attenuation In Deep Coal Mining, Mingwei Zhang, Shengdong Liu, Shuzhao Chen, Yanlong Chen, Guang Xu, Deyu Qian
Focus Energy Determination Of Mining Microseisms Using Residual Seismic Wave Attenuation In Deep Coal Mining, Mingwei Zhang, Shengdong Liu, Shuzhao Chen, Yanlong Chen, Guang Xu, Deyu Qian
Mining Engineering Faculty Research & Creative Works
Based on the energy attenuation characteristics of residual wave in deep rock, a method was developed to determine the microseismic focus energy. Differential energy loss in infinitesimal spreading distance is logically deduced, upon which energy attenuation equation was established. With a logarithmic transformation, a linear relation of the residual seismic energy with distance is formulated. Its intercept was used to determine the microseismic focus energy. The result is compared with that determined by the energy density method. The reliability of the determined focus energy and the impact of the built-in velocity threshold on the residual wave energy computation are discussed. …
Non-Gaussian Analysis Of Wind Velocity Data For The Determination Of Power Quality Control, Jonathan Blackledge, Eugene Coyle, Derek Kearney
Non-Gaussian Analysis Of Wind Velocity Data For The Determination Of Power Quality Control, Jonathan Blackledge, Eugene Coyle, Derek Kearney
Articles
The quality of power (i.e. the sustainable power output as a function time) of any wind dependent energy converter (including wind turbines and wave energy converters) is determined by many design and environmental factors but timedependent variations in the wind speed are arguably the most important. In this paper we consider a non-Gaussian model for analysing and then simulating wind velocity data. In particular, we consider a Lévy distribution for the statistical characteristics of wind velocity and show how this distribution can be used to derive a stochastic fractional diffusion equation for the wind velocity as a function of time …
Wind Turbine Power Quality Estimation Using A Lévy Model For Wind Velocity Data, Jonathan Blackledge, Eugene Coyle, Derek Joseph Kearney
Wind Turbine Power Quality Estimation Using A Lévy Model For Wind Velocity Data, Jonathan Blackledge, Eugene Coyle, Derek Joseph Kearney
Conference papers
The power quality of a wind turbine is determined by many factors but time-dependent variation in the wind velocity are arguably the most important. In this paper a non-Gaussian model for the wind velocity is introduced that is based on a Lévy distribution. It is shown how this distribution can be used to derive a stochastic fractional diffusion equation for the wind velocity as a function of time whose solution is characterised by the Lévy index. A numerical method for computing the L´evy index from wind velocity time series is introduced and applied to example wind velocity data for both …