Mooring System

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Shuzhi Sam Ge - One of the best experts on this subject based on the ideXlab platform.

  • robust adaptive control of a thruster assisted position Mooring System
    Automatica, 2014
    Co-Authors: Wei He, Shuang Zhang, Shuzhi Sam Ge
    Abstract:

    In this paper, robust adaptive control is developed for a thruster assisted position Mooring System in the transverse direction. To provide an accurate and concise representation for the dynamic behavior of the Mooring System, the flexible Mooring lines are modeled as a distributed parameter System of partial differential equations (PDEs). The proposed control is applied at the top boundary of the Mooring lines for station keeping via Lyapunov's direct method. Adaptive control is designed to handle the System parametric uncertainties. With the proposed robust adaptive control, uniform boundedness of the System under the ocean current disturbance is achieved. The proposed control is implementable with actual instrumentations since all the signals in the control can be measured by sensors or calculated by using a backward difference algorithm. The effectiveness of the proposed control is verified by numerical simulations.

  • Modeling and control design for a multi-cable Mooring System
    Proceedings of the 31st Chinese Control Conference, 2012
    Co-Authors: Wei He, Shuzhi Sam Ge, Shuang Zhang
    Abstract:

    In this paper, modeling and control are investigated for a multi-cable Mooring System. The mathematical model of the System is described as partial differential equations (PDEs) via the Hamilton's principle. Control is designed at the top boundary of the Mooring lines based on the Lyapunov's direct method to suppress the vessel's vibrations. Adaptive control is developed to handle the System parametric uncertainties. With the proposed boundary control, uniform boundedness of the System is achieved. Simulations are carried out to verify the effectiveness of the proposed control.

Jinping Ou - One of the best experts on this subject based on the ideXlab platform.

  • optimal design and hydrodynamic response analysis of deep water Mooring System with submerged buoys
    Ships and Offshore Structures, 2018
    Co-Authors: Dongsheng Qiao, Jinping Ou
    Abstract:

    ABSTRACTBased on the traditional catenary Mooring System, a new optimised Mooring System with submerged buoys is proposed. The idea and method in optimal design of Mooring System with buoys are introduced first. Then, the governing equations of Mooring line and the coupled model of platform with its Mooring System are built. Finally, the global responses of a semi-submersible platform with Mooring lines attached buoys are numerically simulated in time domain, and the effects of buoy size and position are investigated. The results would be helpful for expanding the design water depth of catenary Mooring System.

  • applicability analysis of truncated Mooring System based on static and damping equivalence
    Ocean Engineering, 2018
    Co-Authors: Yong Cheng, Chaohe Chen, Jinping Ou
    Abstract:

    Abstract Physical model tests of floating facilities in deep and ultra-deep water with full-depth Mooring System present obstacles because no wave basin is sufficiently large to perform model testing in reasonable scale. The truncated Mooring System needs to be designed to reproduce the statics and Mooring-induced damping exerted by the full-depth Mooring System. Numerical simulation is developed in this paper to analyse the applicability of an innovative approach which designs truncated Mooring System based on static and damping equivalence. Considering the catenary, semi-taut and taut Mooring Systems used for a semi-submersible platform of 1500 m water depths, equivalent truncated Mooring Systems are designed by using the innovative approach, respectively. The motion responses of the platform with full-depth and truncated Mooring Systems are calculated. The applicability of this innovative approach for deepwater model test is discussed.

  • innovative approach to design truncated Mooring System based on static and damping equivalent
    Ships and Offshore Structures, 2014
    Co-Authors: Dongsheng Qiao, Jinping Ou
    Abstract:

    An innovative approach is developed to design equivalent truncated Mooring System for hybrid model testing. Considering the gravity, tension, current force and Mooring line extension, the piecewise extrapolating method is employed to the static analysis of the multi-component Mooring line. In addition, the quasi-static approach and dissipated energy model are used to figure out the Mooring-induced damping of Mooring System. Employing genetic algorithm, an optimised design program is developed to design equivalent truncated Mooring System based on the similarity of both static and damping characteristics. Considering the catenary, semi-taut and taut Mooring Systems used for some semi-submersible platform of 1500 m water depths, equivalent truncated Mooring System is designed by using the design program in this paper, respectively. The results prove that the design program is available for all common types of deep water Mooring System and can be used for hybrid model testing.

Zhi Ming Yuan - One of the best experts on this subject based on the ideXlab platform.

  • numerical study on a hybrid Mooring System with clump weights and buoys
    Ocean Engineering, 2014
    Co-Authors: Zhi Ming Yuan, Atilla Incecik, Chunyan Ji
    Abstract:

    A new hybrid Mooring System based on the traditional taut Mooring lines was proposed in the present study. A series of clump weights were attached to the lower end of each Mooring line to form a catenary shape. Some buoys were connected to the upper ends of the lines to reduce the top tension on each Mooring line. In order to verify the advantages of this new hybrid System, we investigated the motion responses of a semi-submersible platform moored by the proposed hybrid Mooring System. The top tension on the lines was also calculated by using the time domain method. Comparing the results from the taut Mooring System, it can be found that the tension on the lines could be reduced by using the present hybrid Mooring System, while the motion responses were hardly influenced. Furthermore, a catenary shape was formed at the lower end of each Mooring line, which could reduce the requirement of the anti-uplift capacity of the anchors. We also carried out the parametric study to investigate the optimal position and volume of the buoys. The discussions were highlighted on the influence of the water depth.

  • Experimental study of a hybrid Mooring System
    Journal of Marine Science and Technology, 2014
    Co-Authors: Chunyan Ji, Zhi Ming Yuan
    Abstract:

    Mooring Systems are essential to the floating structures including offshore platforms, wave energy converters and floating breakwaters. As floating structures propagate towards deeper waters, the design of the Mooring Systems needs to be revamped. In the present study, a new hybrid Mooring System has been proposed. A series of weights and buoys are arranged to the different segments of each Mooring line in order to improve the motion performance of the platform and eliminate the vertical forces at the lower end of the Mooring lines. A series of experiments have been carried out at CSSRC wave basin for a semi-submersible platform moored by the Mooring lines with or without the weights and buoys. The Mooring lines’ tension and 6-DOF motions of the platform were measured. Discussions have been made on non-linear motion responses of the semi-submersible and non-linear Mooring line tension responses for various Mooring conditions.

  • Numerical study on a hybrid Mooring System with clump weights and buoys
    Ocean Engineering, 2014
    Co-Authors: Zhi Ming Yuan, Atilla Incecik, Chunyan Ji
    Abstract:

    A new hybrid Mooring System based on the traditional taut Mooring lines was proposed in the present study. A series of clump weights were attached to the lower end of each Mooring line to form a catenary shape. Some buoys were connected to the upper ends of the lines to reduce the top tension on each Mooring line. In order to verify the advantages of this new hybrid System, we investigated the motion responses of a semi-submersible platform moored by the proposed hybrid Mooring System. The top tension on the lines was also calculated by using the time domain method. Comparing the results from the taut Mooring System, it can be found that the tension on the lines could be reduced by using the present hybrid Mooring System, while the motion responses were hardly influenced. Furthermore, a catenary shape was formed at the lower end of each Mooring line, which could reduce the requirement of the anti-uplift capacity of the anchors. We also carried out the parametric study to investigate the optimal position and volume of the buoys. The discussions were highlighted on the influence of the water depth. © 2014 Published by Elsevier Ltd. All rights reserved.

  • study on a new Mooring System integrating catenary with taut Mooring
    China Ocean Engineering, 2011
    Co-Authors: Chunyan Ji, Zhi Ming Yuan, Minglu Chen
    Abstract:

    Analyzed are the merits and demerits of catenary Mooring System and taut Mooring System, which are commonly used nowadays. As falling somewhere between these two Systems, a new Mooring System integrating catenary with taut Mooring is proposed. In order to expound and prove the advantages of this new System, the motion performance of a semi-submersible platform is simulated by employing full time domain coupled analysis method. A comparison of the result of new Mooring System with that of taut Mooring System shows that the movement of the platform using the new type Mooring System is smaller than that using the taut Mooring System, which ensures a better working condition. Furthermore, the new Mooring System is also compatible with the characteristics of catenary Mooring System, which eliminates the requirement of anti-uplift capacity of the anchors.

  • coupled analysis of floating structures with a new Mooring System
    ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011
    Co-Authors: Zhi Ming Yuan, Chunyan Ji, Minglu Chen, Yun Zhang
    Abstract:

    As the exploitation of hydrocarbon reserves moves towards deeper waters, the floating structures are becoming more and more popular, and the catenary and taut Mooring Systems are two widespread Mooring Systems which are used for these floating structures. However, both of them have their inherent drawbacks. The aim of the present work is to develop and validate a new Mooring System which will overcome these shortcomings. To this end, the motion performance of a semi-submersible platform is simulated by employing a full time domain coupled analysis method. It is shown that the new Mooring System yields very good motion performance when benchmarked against the taut Mooring System, and the reasons for this improved performance are discussed. Also, the new Mooring System is compatible with the characteristic of catenary Mooring System, which eliminates the requirement of anti-uplift capacity of the anchors. The second aim of this paper is to explore the proper water depth in employing this new Mooring System. For this purpose, several typical water depths are simulated. It is found that the new Mooring System works well both in deep water and ultra-deep water. But, as the water depth becomes deeper, the advantages of the new Mooring System are reduced.Copyright © 2011 by ASME

Chunyan Ji - One of the best experts on this subject based on the ideXlab platform.

  • numerical study on a hybrid Mooring System with clump weights and buoys
    Ocean Engineering, 2014
    Co-Authors: Zhi Ming Yuan, Atilla Incecik, Chunyan Ji
    Abstract:

    A new hybrid Mooring System based on the traditional taut Mooring lines was proposed in the present study. A series of clump weights were attached to the lower end of each Mooring line to form a catenary shape. Some buoys were connected to the upper ends of the lines to reduce the top tension on each Mooring line. In order to verify the advantages of this new hybrid System, we investigated the motion responses of a semi-submersible platform moored by the proposed hybrid Mooring System. The top tension on the lines was also calculated by using the time domain method. Comparing the results from the taut Mooring System, it can be found that the tension on the lines could be reduced by using the present hybrid Mooring System, while the motion responses were hardly influenced. Furthermore, a catenary shape was formed at the lower end of each Mooring line, which could reduce the requirement of the anti-uplift capacity of the anchors. We also carried out the parametric study to investigate the optimal position and volume of the buoys. The discussions were highlighted on the influence of the water depth.

  • Experimental study of a hybrid Mooring System
    Journal of Marine Science and Technology, 2014
    Co-Authors: Chunyan Ji, Zhi Ming Yuan
    Abstract:

    Mooring Systems are essential to the floating structures including offshore platforms, wave energy converters and floating breakwaters. As floating structures propagate towards deeper waters, the design of the Mooring Systems needs to be revamped. In the present study, a new hybrid Mooring System has been proposed. A series of weights and buoys are arranged to the different segments of each Mooring line in order to improve the motion performance of the platform and eliminate the vertical forces at the lower end of the Mooring lines. A series of experiments have been carried out at CSSRC wave basin for a semi-submersible platform moored by the Mooring lines with or without the weights and buoys. The Mooring lines’ tension and 6-DOF motions of the platform were measured. Discussions have been made on non-linear motion responses of the semi-submersible and non-linear Mooring line tension responses for various Mooring conditions.

  • Numerical study on a hybrid Mooring System with clump weights and buoys
    Ocean Engineering, 2014
    Co-Authors: Zhi Ming Yuan, Atilla Incecik, Chunyan Ji
    Abstract:

    A new hybrid Mooring System based on the traditional taut Mooring lines was proposed in the present study. A series of clump weights were attached to the lower end of each Mooring line to form a catenary shape. Some buoys were connected to the upper ends of the lines to reduce the top tension on each Mooring line. In order to verify the advantages of this new hybrid System, we investigated the motion responses of a semi-submersible platform moored by the proposed hybrid Mooring System. The top tension on the lines was also calculated by using the time domain method. Comparing the results from the taut Mooring System, it can be found that the tension on the lines could be reduced by using the present hybrid Mooring System, while the motion responses were hardly influenced. Furthermore, a catenary shape was formed at the lower end of each Mooring line, which could reduce the requirement of the anti-uplift capacity of the anchors. We also carried out the parametric study to investigate the optimal position and volume of the buoys. The discussions were highlighted on the influence of the water depth. © 2014 Published by Elsevier Ltd. All rights reserved.

  • study on a new Mooring System integrating catenary with taut Mooring
    China Ocean Engineering, 2011
    Co-Authors: Chunyan Ji, Zhi Ming Yuan, Minglu Chen
    Abstract:

    Analyzed are the merits and demerits of catenary Mooring System and taut Mooring System, which are commonly used nowadays. As falling somewhere between these two Systems, a new Mooring System integrating catenary with taut Mooring is proposed. In order to expound and prove the advantages of this new System, the motion performance of a semi-submersible platform is simulated by employing full time domain coupled analysis method. A comparison of the result of new Mooring System with that of taut Mooring System shows that the movement of the platform using the new type Mooring System is smaller than that using the taut Mooring System, which ensures a better working condition. Furthermore, the new Mooring System is also compatible with the characteristics of catenary Mooring System, which eliminates the requirement of anti-uplift capacity of the anchors.

  • coupled analysis of floating structures with a new Mooring System
    ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011
    Co-Authors: Zhi Ming Yuan, Chunyan Ji, Minglu Chen, Yun Zhang
    Abstract:

    As the exploitation of hydrocarbon reserves moves towards deeper waters, the floating structures are becoming more and more popular, and the catenary and taut Mooring Systems are two widespread Mooring Systems which are used for these floating structures. However, both of them have their inherent drawbacks. The aim of the present work is to develop and validate a new Mooring System which will overcome these shortcomings. To this end, the motion performance of a semi-submersible platform is simulated by employing a full time domain coupled analysis method. It is shown that the new Mooring System yields very good motion performance when benchmarked against the taut Mooring System, and the reasons for this improved performance are discussed. Also, the new Mooring System is compatible with the characteristic of catenary Mooring System, which eliminates the requirement of anti-uplift capacity of the anchors. The second aim of this paper is to explore the proper water depth in employing this new Mooring System. For this purpose, several typical water depths are simulated. It is found that the new Mooring System works well both in deep water and ultra-deep water. But, as the water depth becomes deeper, the advantages of the new Mooring System are reduced.Copyright © 2011 by ASME

R Pascoal - One of the best experts on this subject based on the ideXlab platform.

  • Mooring System influence on the efficiency of wave energy converters
    International Journal of Marine Energy, 2013
    Co-Authors: Frederico Cerveira, Nuno Fonseca, R Pascoal
    Abstract:

    Abstract The paper presents an analysis of the Mooring System effects on the dynamics of an arbitrary floating wave energy converter (WEC) and on the efficiency of the device. The Mooring System dynamics are calculated by a finite differences method, which accounts for the lines’ physical characteristics such as mass and stiffness, as well as for the hydrodynamic inertial and damping characteristics. A method is proposed and applied to consider the inertial, damping and stiffness effects of the Mooring System on the WEC’s linear dynamics. An identification method is used to determine the linear Mooring System coefficients from pre-calculated nonlinear time domain forces of the Mooring System on the floater (the importance of nonlinear effects is assessed as well). Finally the Mooring System dynamics is represented by additional inertial, damping and stiffness matrices which are added to the ones of the WEC. The influence of the Mooring System on the WEC dynamics and efficiency is assessed in terms of wave induced motions and absorbed power. Results are presented for the transfer functions, statistics in selected stationary sea states and the expected annual absorbed energy. A wave scatter diagram representative of the Portuguese Pilot Zone is used for the annual predictions.