The Experts below are selected from a list of 2586 Experts worldwide ranked by ideXlab platform

Aoli Zhang - One of the best experts on this subject based on the ideXlab platform.

  • optimal tracking control with feedforward compensation for offshore steel Jacket Platforms with active mass damper mechanisms
    Journal of Vibration and Control, 2016
    Co-Authors: Aoli Zhang, Yujia Liu, Gongyou Tang
    Abstract:

    This paper presents the optimal tracking control methodology for an offshore steel Jacket Platform subject to external wave force. Based on a dynamic model of an offshore steel Jacket Platform with...

  • network based modelling and active control for offshore steel Jacket Platform with tmd mechanisms
    Journal of Sound and Vibration, 2014
    Co-Authors: Aoli Zhang
    Abstract:

    Abstract The network-based modelling and active control for an offshore steel Jacket Platform with an active tuned mass damper mechanism is investigated. A network-based dynamic model of the offshore Platform is first established. A network-based state feedback control scheme is developed. Under this scheme, the corresponding closed-loop system is modelled by a system with an artificial interval time-varying delay. Then, a delay-dependent stability criterion for the corresponding closed-loop system is derived. Based on this stability criterion, a sufficient condition on the existence of the network-based controller is obtained. It is found through simulation results that (i) both the oscillation amplitudes of the offshore Platform and the required control force under the network-based state feedback controller are smaller than those under the nonlinear controller and the dynamic output feedback controller; (ii) the oscillation amplitudes of the offshore steel Jacket Platform under the network-based feedback controller are almost the same as the ones under the integral sliding mode controller, while the required control force by the former is smaller than the one by the latter.

Torgeir Moan - One of the best experts on this subject based on the ideXlab platform.

  • UNCERTAINTY AND RELIABILITY ANALYSIS OF Jacket Platform
    Journal of Structural Engineering-asce, 1992
    Co-Authors: Arnt Olufsen, Bernt J. Leira, Torgeir Moan
    Abstract:

    Reliability analysis of a Jacket Platform presently operating in the North Sea is performed. The limit states correspond to design criteria for each structural component. For the tubular columns, beam buckling, shell buckling and maximum allowable stress are considered. For the tubular joints the punching shear failure mode is analyzed. A slightly redesigned version of the Jacket is also considered for assessment of the inherent reliability level of the relevant design code. Latin hypercube sampling is employed for simulating vectors of realizations of basic variables. Probability distributions of extreme dynamic load effects are subsequently identified based on a sequence of response analyses. Reliability analysis is performed for selected structural components by FORM/SORM techniques. For a representative set of structural elements, the random variables influencing the load effects are ranked by means of results from an uncertainty analysis. Similarly, importance measures obtained as by‐products of the ...

Mohammad Reza Tabeshpour - One of the best experts on this subject based on the ideXlab platform.

  • Spectral fatigue analysis of Jacket Platform under wave load equipped with viscous damper
    Journal of Marine Science and Technology, 2019
    Co-Authors: Hossein Janbazi Rokni, Mohammad Reza Tabeshpour
    Abstract:

    Offshore Jacket Platforms are exposed to environmental loads such as wind, wave, current, and earthquake throughout the lifetime of operation. Due to dynamic and periodic nature and fatigue phenomenon in the structure, wave forces are the most important loads among others. There are diverse methods to explore the fatigue life of Jackets, including deterministic, spectral, and time domain analysis. Among these methods, spectral method is a reliable method, which considers the random nature of sea waves in fatigue analysis. In the current study, a spectral method is introduced for assessment and rehabilitation of Jacket Platform structure. To this end, a computer program has been developed, meanwhile, probability spectral density functions of displacement and stress are calculated in each joint of Jacket elements. Furthermore, using S – N curve approach, cumulative fatigue damage in critical members of an example Jacket is obtained. Finally, several configurations of viscous dampers are applied to Jacket, and damage and fatigue lifetime are discussed with and without dampers. Consequently, the best arrangement of dampers is achieved. Results indicate the best cumulative fatigue damage with dampers which was about 0.01 times of cumulative fatigue damage without a damper.

Baolin Zhang - One of the best experts on this subject based on the ideXlab platform.

  • network based control for offshore steel Jacket Platform subject to wave induced force
    Conference of the Industrial Electronics Society, 2013
    Co-Authors: Baolin Zhang, Guannan Zhang, Qinglong Han
    Abstract:

    This paper is concerned with network-based control for an offshore steel Jacket Platform subject to nonlinear wave-induced force. A network-based dynamic model of the offshore Platform is presented and a network-based state feedback control scheme is developed to reduce the internal oscillations of the offshore Platform. Then the effect of a network-induced delay on the control performance of the offshore Platform is investigated. It is found through simulation results that (i) the network-based state feedback controller is of a smaller gain in the sense of Euclidean norm than the state feedback controller without network setting, which means the network-based state feedback controller requires less control force; and (ii) the network-induced delay is of the positive effect on state feedback control of the offshore Platform.

  • integral sliding mode control for offshore steel Jacket Platforms
    Journal of Sound and Vibration, 2012
    Co-Authors: Xianming Zhang, Baolin Zhang, Xinghuo Yu
    Abstract:

    Abstract This paper is concerned with robust integral sliding mode control for an offshore steel Jacket Platforms subject to nonlinear wave-induced force and parameter perturbations. A robust integral sliding mode controller is designed to stabilize the dynamic model of the offshore steel Jacket Platform. It is shown through simulation results that the robust integral sliding mode control scheme can reduce the internal oscillations of the offshore steel Jacket Platform dramatically; and the performance of the offshore steel Jacket Platform under the robust integral sliding mode control scheme is better than the ones under the nonlinear control scheme and the dynamic output feedback control scheme.

  • An application of guaranteed cost control in offshore steel Jacket Platforms
    2011
    Co-Authors: Baolin Zhang, Pei-ding Shen, Ya-zhou Han
    Abstract:

    The guaranteed cost control(GCC) method with H ∞ disturbance attenuation is investigated for the steel Jacket Platform system when subjected to nonlinear self-excited hydrodynamic forces. A state feedback controller is designed to ensure the asymptotic stability of the steel Jacket Platform system. In the presence of self-excited wave forces, the proposed scheme satisfies H ∞ disturbance attenuation level and guarantees cost upper bound. By Lyapunov stability theory and linear matrix inequality (LMI) approach, a sufficient condition is given to ensure the existence of the guaranteed cost controller. Simulation results are presented to demonstrate the effectiveness of the proposed scheme.

Mohamed Terro - One of the best experts on this subject based on the ideXlab platform.

  • nonlinear and robust control schemes for offshore steel Jacket Platforms
    Nonlinear Dynamics, 2004
    Co-Authors: Mohamed Zribi, Naif Almutairi, Mohamed Abdelrohma, Mohamed Terro
    Abstract:

    This paper presents two control schemes to control the dynamicresponse of an offshore steel Jacket Platform due to wave-inducedforces. The objective of the controllers is to greatly reduce theinternal system oscillations and to obtain a smooth response ofthe steel Jacket Platform when subjected to nonlinear self-excitedhydrodynamic forces. The first controller is a nonlinearcontroller whose design is based on Lyapunov theory. The secondcontroller is a robust state feedback linear controller whosedesign is based on an optimal control approach. Both controlschemes guarantee the asymptotic stability of the system. Thetheoretical developments are illustrated through simulationresults of the proposed control schemes. Furthermore, theperformance of the offshore steel Jacket Platform is presentedwhen a direct velocity feedback controller is applied to thesystem. It is found that the performance of the system with theproposed controllers is better than the performance of the systemwith the direct velocity feedback controller.