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Ren Guang - One of the best experts on this subject based on the ideXlab platform.

  • hardware in loop simulation of Ship speed hybrid error regulator and its Stability analysis
    Computer Simulation, 2010
    Co-Authors: Ren Guang
    Abstract:

    The Stability of Ship speed is determined by the response characteristic of the main engine load regulation system.To restrain the load disturbances and to improve the control precision of Ship speed,a Ship speed hybrid error regulator(SSHER) was proposed based on Lyapunov approach.Its Stability of SSHER was analyzed,and adaptation law of Ship speed was implemented.In laboratory conditions,the hardware-in-loop simulation of SSHER was established.Simulation results show that SSHER can restrain the disturbances,and can enhance the Stability of Ship speed in case of system model uncertainty.

Shahrbaf Darvazehnoie Akbar - One of the best experts on this subject based on the ideXlab platform.

  • Stability of Ships with forward speed
    2007
    Co-Authors: Shahrbaf Darvazehnoie Akbar
    Abstract:

    The initial Stability of Ship is currently evaluated by empirical formula based largely on a static approach. Evidently Stability is affected by speed that causes variation of pressure distribution on the wetted surface of a Ship's hull, and generated waves on the surface of water by the vessel's motion. Forces and moments resulting from bottom pressures, as the speed of the Ship changes, are significantly different for the Ship at rest and in a seaway. The principal aim of the research is to investigate the effect of variations of forward speed on Stability of a Ship in calm water. The thesis presents theoretical and experimental approaches of the research. The novelty of the research results leads to the conclusion that although increasing speed may improve the Stability of a Ship in some cases, it also depends on heeling angle or on any asymmetry of the wetted area of a hull. Taking into account unbalanced pressure distribution acting on the wetted surface of the hull in some cases, hence, decrease of Stability is also possible. On a moving, partially immersed body, hydrodynamic and hydrostatic forces predominate. These forces arise owing to interaction between the body's motion and its weight with respect to the surrounding water. In order to calculate these forces, the panel method of Computational Fluid Dynamics (CFD) has been applied to identify the velocity and pressure distribution on the wetted surface of a Ship's hull. The mathematical model adopted is based on the source distribution on the Ship's hull, known as the Kelvin source. The model for a body travelling with steady forward speed, where its motion does not disturb the free surface, is known as double body theory. For consideration of waves generated by the motion of the Ship on the free surface, a three dimensional linearised potential flow solution has been utilised. Comprehensive tests conducted in the UCL towing tank have established a better understanding of the significance of variation of Ship's Stability associated with forward speed in calm water. It is shown that an accurate judgement regarding the Ship's Stability cannot be made if only the effect of forward speed, as a single parameter, is considered. The heeling angle is another important parameter that must also be taken into account. The effects of a combination of both variables have been investigated, and are reported on. The research is presented showing that the applied CFD method may be an alternative method to assess Stability of a Ship in seaway, but there is a long way for the CFD approach to replace towing tank testing. At present, CFD may be used for consideration as a precursor to improve Ship's Stability in a real sea during the design stage, for modification, and before operation. It is hoped that in future the novel findings of the experimental approach of this research could be used as additional guidance to be incorporated within the Stability documentation for individual Ships at the design stage, and Ship trials.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Yansen Liu - One of the best experts on this subject based on the ideXlab platform.

  • Study on line-spectrum Stability of Ship underwater radiated noise
    2016 IEEE OES China Ocean Acoustics (COA), 2016
    Co-Authors: Xuemeng Yang, Yansen Liu
    Abstract:

    Ship radiated noise is usually comprised of continuously distributed broad-band noises and several narrow-band line spectrum components on discrete frequencies. Generated by periodical machinery rotation and propeller blade rotation, the line spectrum with high strength has its central frequency located in the low frequency range, so that its long-distance transmission loss is small. It is an important information source for passive target detection, tracing and recognition. Due to the comprehensive influence of sound source characteristics, transmission channels and Doppler phenomena, the magnitude and frequency of the line spectrum always fluctuates, which will definitely influence the performance of a sonar system. Addressing the problem, this paper proposes an analytical approach to evaluate the line spectrum Stability of Ship radiated noise. The validity of the method is checked by analyzing actually-measured radiated noise data of a Ship at sea from the perspectives of magnitude and frequency. This research provides a new approach to improve the performance of line spectrum detection.

Xuemeng Yang - One of the best experts on this subject based on the ideXlab platform.

  • Study on line-spectrum Stability of Ship underwater radiated noise
    2016 IEEE OES China Ocean Acoustics (COA), 2016
    Co-Authors: Xuemeng Yang, Yansen Liu
    Abstract:

    Ship radiated noise is usually comprised of continuously distributed broad-band noises and several narrow-band line spectrum components on discrete frequencies. Generated by periodical machinery rotation and propeller blade rotation, the line spectrum with high strength has its central frequency located in the low frequency range, so that its long-distance transmission loss is small. It is an important information source for passive target detection, tracing and recognition. Due to the comprehensive influence of sound source characteristics, transmission channels and Doppler phenomena, the magnitude and frequency of the line spectrum always fluctuates, which will definitely influence the performance of a sonar system. Addressing the problem, this paper proposes an analytical approach to evaluate the line spectrum Stability of Ship radiated noise. The validity of the method is checked by analyzing actually-measured radiated noise data of a Ship at sea from the perspectives of magnitude and frequency. This research provides a new approach to improve the performance of line spectrum detection.

Liu Haihui - One of the best experts on this subject based on the ideXlab platform.

  • pid speed control system in steering process of rudder propeller
    2017
    Co-Authors: Zheng Ruicong, Qiu Xiangyao, Liu Haihui
    Abstract:

    The invention relates to a PID speed control system in a steering process of a rudder propeller. The system includes a master table, a central control box PLC, a variable frequency drive system and a speed encoder. The system can ensure the Stability of Ship operation and prolong service life of a steering system. Steering information are in real time feedback and steering angle is judged automatically and the optimal speed of a Ship is adjusted, so the the Ship can have the optimal steering radius and the Stability of the Ship in the steering process is ensured.