A hydraulic exciting system with a wave exciter has been constructed in order to study the hydraulic vibra- tion law. The system consists of an oil source, wave-exciter and oil cylinder, and is controlled by a wave-ex...A hydraulic exciting system with a wave exciter has been constructed in order to study the hydraulic vibra- tion law. The system consists of an oil source, wave-exciter and oil cylinder, and is controlled by a wave-exciter. The working principle of the hydraulic exciting system and wave exciter has been analyzed, and its excitation process has been illustrated. The law of every pipe＇s pressure fluctuation of the system is obtained by experiment. The theo- retical analysis and experimental data prove that the pipeline pressure periodically changes and the pipeline pressure fluctuation frequency is independently controlled by the excitation frequency of the wave-exciter. Every pipelinc＇s pressure wave is produced by system flow fluctuation and water hammer coupling. The pressure fluctuation rules of the system provide a theoretical basis for the study of the associated liberation system.展开更多
The hydrodynamic interaction between two vertical cylinders in water waves is investigated based on the linearized potential flow theory. One of the two cylinders is fixed at the bottom while the other is articulated ...The hydrodynamic interaction between two vertical cylinders in water waves is investigated based on the linearized potential flow theory. One of the two cylinders is fixed at the bottom while the other is articulated at the bottom and oscillates with small amplitudes in the direction of the incident wave. Both the diffracted wave and the radiation wave are studied in the present paper. A simple analytical expression for the velocity potential on the surface of each cylinder is obtained by means of Graf's addition theorem. The wave-excited forces and moments on the cylinders, the added masses and the radiation damping coefficients of the oscillating cylinder are all expressed explicitly in series form. The coefficients of the series are determined by solving algebraic equations. Several numerical examples are given to illustrate the effects of various parameters, such as the separation distance, the relative size of the cylinders, and the incident angle, on the first-order and steady second-order forces, the added masses and radiation-damping coefficients as well as the response of the oscillating cylinder.展开更多
The real-time prediction of a floating platform or a vessel is essential for motion-sensitive maritime activ-ities.It can enhance the performance of motion compensation system and provide useful early-warning informat...The real-time prediction of a floating platform or a vessel is essential for motion-sensitive maritime activ-ities.It can enhance the performance of motion compensation system and provide useful early-warning information.In this paper,we apply a machine learning technique to predict the surge,heave,and pitch motions of a moored rectangular barge excited by an irregular wave,which is purely based on the mo-tion data.The dataset came from a model test performed in the deep-water ocean basin,at Shanghai Jiao Tong University,China.Using the trained machine learning model,the predictions of 3-DoF(degrees of freedom)motions can extend two to four wave cycles into the future with good accuracy.It shows great potential for applying the machine learning technique to forecast the motions of offshore platforms or vessels.展开更多
基金supported by National Natural Science Foundation of China under Grant No.50775154Shanxi Province Science Foundation of China under Grant No.2011011026-2
文摘A hydraulic exciting system with a wave exciter has been constructed in order to study the hydraulic vibra- tion law. The system consists of an oil source, wave-exciter and oil cylinder, and is controlled by a wave-exciter. The working principle of the hydraulic exciting system and wave exciter has been analyzed, and its excitation process has been illustrated. The law of every pipe＇s pressure fluctuation of the system is obtained by experiment. The theo- retical analysis and experimental data prove that the pipeline pressure periodically changes and the pipeline pressure fluctuation frequency is independently controlled by the excitation frequency of the wave-exciter. Every pipelinc＇s pressure wave is produced by system flow fluctuation and water hammer coupling. The pressure fluctuation rules of the system provide a theoretical basis for the study of the associated liberation system.
文摘The hydrodynamic interaction between two vertical cylinders in water waves is investigated based on the linearized potential flow theory. One of the two cylinders is fixed at the bottom while the other is articulated at the bottom and oscillates with small amplitudes in the direction of the incident wave. Both the diffracted wave and the radiation wave are studied in the present paper. A simple analytical expression for the velocity potential on the surface of each cylinder is obtained by means of Graf's addition theorem. The wave-excited forces and moments on the cylinders, the added masses and the radiation damping coefficients of the oscillating cylinder are all expressed explicitly in series form. The coefficients of the series are determined by solving algebraic equations. Several numerical examples are given to illustrate the effects of various parameters, such as the separation distance, the relative size of the cylinders, and the incident angle, on the first-order and steady second-order forces, the added masses and radiation-damping coefficients as well as the response of the oscillating cylinder.
基金supported by Shanghai Pilot Program for Basic Research-Shanghai Jiao Tong University (No.21TQ1400202).
文摘The real-time prediction of a floating platform or a vessel is essential for motion-sensitive maritime activ-ities.It can enhance the performance of motion compensation system and provide useful early-warning information.In this paper,we apply a machine learning technique to predict the surge,heave,and pitch motions of a moored rectangular barge excited by an irregular wave,which is purely based on the mo-tion data.The dataset came from a model test performed in the deep-water ocean basin,at Shanghai Jiao Tong University,China.Using the trained machine learning model,the predictions of 3-DoF(degrees of freedom)motions can extend two to four wave cycles into the future with good accuracy.It shows great potential for applying the machine learning technique to forecast the motions of offshore platforms or vessels.
