The Experts below are selected from a list of 7947 Experts worldwide ranked by ideXlab platform

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

  • the effects of surge motion of the Floating Platform on hydrodynamics performance of horizontal axis tidal current turbine
    Renewable Energy, 2015
    Co-Authors: Liang Zhang, Qihu Sheng, Shuqi Wang, Fengmei Jing
    Abstract:

    Under practical operation conditions, hydrodynamic characteristics of Floating horizontal-axis turbine are affected by the wave-induced motion response of the Floating Platform for the turbine system. In this thesis, CFX software is adopted to analyze the hydrodynamic performance of the turbine in constant inflow with the turbine being forced vibrating and to study how the hydrodynamic performance of the turbine is influenced by surge frequency, surge amplitude and speed ratio. Based on the simulation data from CFX, axial damping coefficient can be obtained by least square fitting the time-varying axial force curves of surging turbine. The simulation results demonstrate that compared with turbine only rotating in constant inflow, shaft loads and energy utilization ratio of the surging turbine experience oscillations respectively; the oscillation amplitudes of these two parameters have a positive correlation with the frequency and amplitude of the surge and speed ratio; the frequency and amplitude of the surge have little impact on axial damping coefficient but this coefficient is positively proportioned to the rotational speed of the turbine. The results of this study can provide data to study motion response of Floating Platform for Floating tidal current turbine system and control design of the output electricity.

  • Optimal Selection of Floating Platform for Tidal Current Power Station
    Research Journal of Applied Sciences Engineering and Technology, 2013
    Co-Authors: Fengmei Jing, Gang Xiao, Nasir Mehmood, Liang Zhang
    Abstract:

    With continuous development of marine engineering, more and more new structures are used in the exploring of tidal current energy. Three are there different kinds of support structures for tidal current power station, which are sea-bed mounted/gravity based system, pile mounted system and Floating moored Platform. Comparison with them, the Floating mooring system is suit for deep water and the application of which will be widely. In this study, catamaran and semi-submersible as Floating Platform of tidal current power station are studied. And they are compared with its economic, efficiency of turbine and stability of station. It is found that the catamaran is optimal choice. Based on basic ship theory and using software MOSES, the stability of Catamaran tidal current power station is also calculated. The research of this study is significant and it will be as the reference for the future study.

  • direct and full scale experimental verifications towards ground satellite quantum key distribution
    Nature Photonics, 2013
    Co-Authors: Liang Zhang, Jianyu Wang, Bin Yang, Shengkai Liao, Qi Shen, Xiaofang Hu, Jincai Wu, Shiji Yang
    Abstract:

    Full-scale verifications for establishing quantum cryptography communication via satellites are reported. Three independent experiments using a hot-air balloon are performed: on a rapidly moving Platform over a distance of 40 km, on a Floating Platform over a distance of 20 km, and over 96 km in air with a huge loss.

Fengmei Jing - One of the best experts on this subject based on the ideXlab platform.

  • the effects of surge motion of the Floating Platform on hydrodynamics performance of horizontal axis tidal current turbine
    Renewable Energy, 2015
    Co-Authors: Liang Zhang, Qihu Sheng, Shuqi Wang, Fengmei Jing
    Abstract:

    Under practical operation conditions, hydrodynamic characteristics of Floating horizontal-axis turbine are affected by the wave-induced motion response of the Floating Platform for the turbine system. In this thesis, CFX software is adopted to analyze the hydrodynamic performance of the turbine in constant inflow with the turbine being forced vibrating and to study how the hydrodynamic performance of the turbine is influenced by surge frequency, surge amplitude and speed ratio. Based on the simulation data from CFX, axial damping coefficient can be obtained by least square fitting the time-varying axial force curves of surging turbine. The simulation results demonstrate that compared with turbine only rotating in constant inflow, shaft loads and energy utilization ratio of the surging turbine experience oscillations respectively; the oscillation amplitudes of these two parameters have a positive correlation with the frequency and amplitude of the surge and speed ratio; the frequency and amplitude of the surge have little impact on axial damping coefficient but this coefficient is positively proportioned to the rotational speed of the turbine. The results of this study can provide data to study motion response of Floating Platform for Floating tidal current turbine system and control design of the output electricity.

  • Optimal Selection of Floating Platform for Tidal Current Power Station
    Research Journal of Applied Sciences Engineering and Technology, 2013
    Co-Authors: Fengmei Jing, Gang Xiao, Nasir Mehmood, Liang Zhang
    Abstract:

    With continuous development of marine engineering, more and more new structures are used in the exploring of tidal current energy. Three are there different kinds of support structures for tidal current power station, which are sea-bed mounted/gravity based system, pile mounted system and Floating moored Platform. Comparison with them, the Floating mooring system is suit for deep water and the application of which will be widely. In this study, catamaran and semi-submersible as Floating Platform of tidal current power station are studied. And they are compared with its economic, efficiency of turbine and stability of station. It is found that the catamaran is optimal choice. Based on basic ship theory and using software MOSES, the stability of Catamaran tidal current power station is also calculated. The research of this study is significant and it will be as the reference for the future study.

Jing Feng-mei - One of the best experts on this subject based on the ideXlab platform.

  • Strength analysis on Floating Platform of tidal current power station
    Journal of Ship Mechanics, 2013
    Co-Authors: Jing Feng-mei
    Abstract:

    The Floating tidal current power station is used to transfer the tidal current energy into power energy. Because of the complexity of its structure and the particularity of the loads, theories and criterions existed can not be used directly to evaluate the overall strength of the power station. Based on the potential theory, software of Hydrostar is used to simulate the wave loads; and hydrodynamics loads of the turbine are calculated using CFX. Turbine loads are equivalented and transformed reasonably. ‘Equivalent rigid shaft' method is used to apply loads on the structure, and plant carrier (Floating Platform) strength is calculated by finite element method. The calculation results show that methods adopted in this paper can truly reflect features of stress distribution of the support structure, and strength of the carrier satisfies the working requirements of the turbine.

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

  • Embedded Power Take-Off in hinged modularized Floating Platform for wave energy harvesting and pitch motion suppression
    Renewable Energy, 2019
    Co-Authors: Haicheng Zhang, Ding Rui, Zhao Huai
    Abstract:

    Abstract Wave energy converters (WECs) based on the hydraulic Power Take-Off (PTO) mechanism are proposed in conjunction with a modularized Floating Platform for the wave energy harvesting and pitch motion suppression of the Platform. A rigid multi-body dynamic model is developed where the WEC is considered as a linear damper to absorb the kinetic energy of the Platform induced by waves. Numerical analysis is firstly carried out for a four-modular semi-submersible Floating Platform. The effect of the PTOs on the pitch responses of the hinged Floating Platform is studied in irregular waves, and an optimal balance between the energy extraction and pitch suppression is achievable. Taking capture width of energy extraction as an objective function, the damping coefficient of the PTOs is optimally determined by combining an external penalty function method and the Hooke Jeeves method. Further the effect of the number of Floating modules on the energy absorption and responses of the Floating system is evaluated.

  • Energy extraction of wave energy converters embedded in a very large modularized Floating Platform
    Energy, 2018
    Co-Authors: Haicheng Zhang, Zhao Huai, Shuyan Xia
    Abstract:

    Abstract An embedded wave energy converter installed in a super-scale modularized Floating Platform is proposed for wave-induced kinetic energy extraction. The Platform consists of multiple blocks where on-top huge modular decks are flexibly supported by Floating semi-submergible modules via elastic cushions. For the connection between adjacent blocks, neighboring decks are joined by rigid hinges and neighboring Floating modules are connected by two piston-type devices that are embedded wave energy converters (WEC), designed by the linear hydraulic power take-off (PTO) mechanism. Based on linear wave theory and rigid module flexible connector (RMFC), the dynamic model for the modularized Floating Platform is developed by using a network modeling method. In numerical case studies, the wave energy extraction of a five-block Platform is investigated and the design region for the key parameters of the WEC is recommended. In addition the effects of the WECs on the dynamic responses and the connector loads of the modularized Platform are studied. These results can improve the understanding on the performance of the specific Platform.

  • Experimental validation of network modeling method on a three-modular Floating Platform model
    Coastal Engineering, 2018
    Co-Authors: Q.j. Shi, Haicheng Zhang, C. Tian, J. Ding
    Abstract:

    Abstract This paper reports an experimental verification of a network modeling method that is recently proposed for forecasting responses of multi-modular Floating Platforms in regular waves. A three-dimensional network modeling method is presented, which includes the geometric effect of connectors and permits nonlinear dynamic analysis of the Floating system. In the validation study, a three-modular Floating Platform model is fabricated for experimental test in wave basin. Both the linear model and nonlinear model of the network modeling method are examined in the collation of the hydro-elastic method and experiment test. The responses of modules and loads of connectors are employed for the comparison study. The results show that the linear model of the network modeling method is the closest to the test results and outperforms over the nonlinear model and the hydro-elastic method. The possible reasons of the discrepancy in the results of the different methods are discussed. This work validates that the network modeling method is reliable.

Eric W Gill - One of the best experts on this subject based on the ideXlab platform.

  • motion compensation for high frequency surface wave radar on a Floating Platform
    Iet Radar Sonar and Navigation, 2018
    Co-Authors: Eric W Gill, Weimin Huang
    Abstract:

    A method for mitigating antenna motion effects in high-frequency radar Doppler spectra developed from ocean backscatter is proposed. On the basis of the established radar cross-section models for a fixed antenna and for an antenna on a Floating Platform, the relationship between these models is examined. Through this relationship, motion compensation can be achieved by deconvolving the radar cross-section data with the derived transfer function. Four different deconvolution methods are illustrated and discussed in this study. Calculations involving a radar cross-section model, incorporating external noise, for an antenna on a Floating Platform are conducted in order to simulate field data and to examine this motion compensation method. The external noise is characterised as a white Gaussian zero-mean process. By using this newly developed radar cross-section model with external noise, motion compensation results under different sea states are examined. The outcomes indicate that an iterative Tikhonov regularisation deconvolution technique is superior to the other compensation methods implemented in this study.

  • the second order high frequency radar ocean surface foot scatter cross section for an antenna on a Floating Platform
    IEEE Transactions on Antennas and Propagation, 2013
    Co-Authors: J Walsh, Weimin Huang, Eric W Gill
    Abstract:

    While the first-order and a portion of the second-order scattering mechanism for high frequency surface wave radar signals from the ocean surface for the case of the antennas being mounted on a Floating Platform have been addressed earlier, here the case of one of two scatters occurring near the transmitting and/or receiving antenna is considered. The relevant fields, reduced to monostatic form for the case of a pulsed dipole source and a time-invariant rough surface, are extended to include the ocean surface, which is considered to be a zero-mean Gaussian process. The new contributions to the radar cross section (RCS) again appear as Bessel functions, which give rise to additional features in the overall RCS. The effects are generally much smaller than those associated with the first-order scattering except at specific frequencies in the spectral regions beyond the peaks of the usual second-order energy and also near zero Doppler.

  • further analysis of the modulation of high frequency radar spectra due to sea induced antenna Platform motion
    OCEANS'10 IEEE SYDNEY, 2010
    Co-Authors: J Walsh, Eric W Gill, Bernard Ryan, Jacques El Khoury
    Abstract:

    The scattering of high frequency electromagnetic waves from the ocean surface is considered for the case of the radiation source being a vertical pulsed antenna mounted on a Floating Platform while the receiving antenna is fixed on the shore. This represents a small extension to an earlier analysis by Walsh in which both the transmitting (TX) and receiving (RX) antennas were co-located on a Floating Platform and the effect of the sway was accounted for in the ocean cross section. It is known that additional features appear in the Doppler spectrum when the RX and TX antennas are permitted to sway slowly, and here a similar result is shown when only the TX antenna moves. It is seen in this case that the magnitude of the additional spectral features is reduced as compared to the case when both antennas are moving. As a motivation for continuing analytical work, a preliminary field result is depicted.