A robust H∞sampled-data stabilization problem for nonlinear dynamic positioning(DP) ships with Takagi-Sugeno(T-S) fuzzy models is discussed in this paper. Input delay approach is used to convert the sampleddata DP sh...A robust H∞sampled-data stabilization problem for nonlinear dynamic positioning(DP) ships with Takagi-Sugeno(T-S) fuzzy models is discussed in this paper. Input delay approach is used to convert the sampleddata DP ship system to a fuzzy system with time-varying delay. Adequate conditions are derived to determine the system's asymptotical stability and achieve H∞performance via Lyapunov stability theorems. Then, the fuzzy sampled-data controller is obtained by analyzing the stabilization condition. Simulation result shows that the proposed method and the designed controller for a DP ship are effective so that the DP ship can maintain the desired position, heading and velocities in the existence of varying environment disturbances.展开更多
Comfort levels on modern superyachts have recently been the object of specific attention of the most important Classification Societies, which issued new rules and regulations for evaluating noise and vibration maximu...Comfort levels on modern superyachts have recently been the object of specific attention of the most important Classification Societies, which issued new rules and regulations for evaluating noise and vibration maximum levels. These rules are named "Comfort Class Rules" and set the general criteria for noise and vibration measurements in different vessels' areas, as well as the maximum noise and vibration limit values. As far as the vibration assessment is concerned, the Comfort Class Rules follow either the ISO 6954:1984 standard or the ISO 6954:2000. After an introduction to these relevant standards, the authors herein present a procedure developed to predict the vibration levels on ships. This procedure builds on finite element linear dynamic analysis and is applied to predict the vibration levels on a 60 m superyacht considered as a case study. The results of the numerical simulations are then benchmarked against experimental data acquired during the sea trial of the vessel. This analysis also allows the authors to evaluate the global damping ratio to be used by designers in the vibration analysis of superyachts.展开更多
Today,ship development has concentrated on electrifying ships in commercial and military applications to improve efficiency,support highpower missile systems and reduce emissions.However,the electric propulsion of the...Today,ship development has concentrated on electrifying ships in commercial and military applications to improve efficiency,support highpower missile systems and reduce emissions.However,the electric propulsion of the shipboard system experiences torque fluctuation,thrust,and power due to the rotation of the propeller shaft and the motion of waves.In order tomeet these challenges,a new solution is needed.This paper explores hybrid energy management systems using the battery and ultracapacitor to control and optimize the electric propulsion system.The battery type and ultracapacitor are ZEBRA and MAXWELL,respectively.The 3-,4-and 5-blade propellers are considered to produce power and move rapidly.The loss factor has been reduced,and the sea states have been found through the Elephant Herding Optimization algorithm.The efficiency of the proposed system is greatly enhanced through torque,thrust and power.The model predictive controller control strategy is activated to reduce load torque and drive system Root Average Square(RMS)error.The implementations are conducted under the MATLAB platform.The values for torque,current,power,and error are measured and plotted.Finally,the performance of the proposed methodology is compared with other available algorithms such as BAT and Dragonfly(DF).The simulation results show that the results of the proposed method are superior to those of various techniques and algorithms such as BAT and Dragonfly.展开更多
基金the National Natural Science Foundation of China(No.51579114)the Project of New Century Excellent Talents of Colleges and Universities of Fujian Province(No.JA12181)the Project of Young and Middle-Aged Teacher Education of Fujian Province(No.JAT170309)
文摘A robust H∞sampled-data stabilization problem for nonlinear dynamic positioning(DP) ships with Takagi-Sugeno(T-S) fuzzy models is discussed in this paper. Input delay approach is used to convert the sampleddata DP ship system to a fuzzy system with time-varying delay. Adequate conditions are derived to determine the system's asymptotical stability and achieve H∞performance via Lyapunov stability theorems. Then, the fuzzy sampled-data controller is obtained by analyzing the stabilization condition. Simulation result shows that the proposed method and the designed controller for a DP ship are effective so that the DP ship can maintain the desired position, heading and velocities in the existence of varying environment disturbances.
文摘Comfort levels on modern superyachts have recently been the object of specific attention of the most important Classification Societies, which issued new rules and regulations for evaluating noise and vibration maximum levels. These rules are named "Comfort Class Rules" and set the general criteria for noise and vibration measurements in different vessels' areas, as well as the maximum noise and vibration limit values. As far as the vibration assessment is concerned, the Comfort Class Rules follow either the ISO 6954:1984 standard or the ISO 6954:2000. After an introduction to these relevant standards, the authors herein present a procedure developed to predict the vibration levels on ships. This procedure builds on finite element linear dynamic analysis and is applied to predict the vibration levels on a 60 m superyacht considered as a case study. The results of the numerical simulations are then benchmarked against experimental data acquired during the sea trial of the vessel. This analysis also allows the authors to evaluate the global damping ratio to be used by designers in the vibration analysis of superyachts.
文摘Today,ship development has concentrated on electrifying ships in commercial and military applications to improve efficiency,support highpower missile systems and reduce emissions.However,the electric propulsion of the shipboard system experiences torque fluctuation,thrust,and power due to the rotation of the propeller shaft and the motion of waves.In order tomeet these challenges,a new solution is needed.This paper explores hybrid energy management systems using the battery and ultracapacitor to control and optimize the electric propulsion system.The battery type and ultracapacitor are ZEBRA and MAXWELL,respectively.The 3-,4-and 5-blade propellers are considered to produce power and move rapidly.The loss factor has been reduced,and the sea states have been found through the Elephant Herding Optimization algorithm.The efficiency of the proposed system is greatly enhanced through torque,thrust and power.The model predictive controller control strategy is activated to reduce load torque and drive system Root Average Square(RMS)error.The implementations are conducted under the MATLAB platform.The values for torque,current,power,and error are measured and plotted.Finally,the performance of the proposed methodology is compared with other available algorithms such as BAT and Dragonfly(DF).The simulation results show that the results of the proposed method are superior to those of various techniques and algorithms such as BAT and Dragonfly.
