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Wyszukujesz frazę "Liu, L.-L." wg kryterium: Autor

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    Wyświetlanie 1-8 z 8
    Tytuł:
    Nonlinear PTO effect on performance of vertical axisymmetric wave energy converter using semi-analytical method
    Autorzy:
    Liu, M.
    Liu, H.
    Zheng, X.
    Chen, H.
    Wang, L.
    Zhang, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/258878.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    wave energy converter (WEC)
    power take-off (PTO)
    capture width ratios
    analytical method
    eigen function
    Opis:
    The wave energy, as a clean and non-pollution renewable energy sources, has become a hot research topic at home and abroad and is likely to become a new industry in the future. In this article, to effectively extract and maximize the energy from ocean waves, a vertical axisymmetric wave energy converter (WEC) was presented according to investigating of the advantages and disadvantages of the current WEC. The linear and quadratic equations in frequency-domain for the reactive controlled single-point converter property under regular waves condition are proposed for an efficient power take-off (PTO). A method of damping coefficients, theoretical added mass and exciting force are calculated with the analytical method which is in use of the series expansion of eigen functions. The loads of optimal reactive and resistive, the amplitudes of corresponding oscillation, and the width ratios of energy capture are determined approximately and discussed in numerical results.
    Źródło:
    Polish Maritime Research; 2017, S 3; 49-57
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Research on the maritime logistics pricing model of risk-averse retailer-dominated dual-channel supply chain
    Autorzy:
    Fang, Q.
    Tong, Z.
    Ren, L.
    Liu, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/258648.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    dual channel
    risk-averse
    retailer-dominated
    supply chain
    Opis:
    Price decision is studied in a risk-averse retailer-dominated dual-channel supply chain, which consisting of one manufacturers and one retailer with both off-line and on-line channels. Firstly, two mean-variance models in centralized and decentralized supply chain are established. Secondly, the optimal solutions under the two decision modes are compared and analyzed. The results shows that the price of dual-channel of retailer decreased with the increase of retailers’ risk- aversion coefficient and the standard deviation of the fluctuation of market demand, while the wholesale price changes is on the contrary; in addition, when the market demand is greater than a certain value, the prices of dual channel are correspondingly higher in decentralized supply chain than in centralized supply chain, and vice versa. In addition, when the retailer’s risk aversion is in a certain interval, the expected utility of the whole supply chain is greater in centralized supply chain than in decentralized decision, and vice versa. Finally, a numerical example is given to verify the above conclusions.
    Źródło:
    Polish Maritime Research; 2018, S 2; 107-116
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on the design of container highway and railway automatic transfer vehicle in ocean port
    Autorzy:
    Dong, L.
    Liu, G.
    Ye, X.
    Wang, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/962741.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    ocean port
    multimodal transport
    highway and railway
    unmanned automatic
    seamless connection
    Opis:
    To realize “seamless” connection of ocean port container multimodal transport, efficiently carry out “door-to-door” transport of ocean port containers and overcome the shortcomings of existing highway and railway vehicles, this study takes the standard for heavy-duty container vehicles in TB1335-1996 Railway Vehicle Strength Design and Test Identification Code as the design basis and designs a new ocean port container transport vehicle in combination with automatic guidance technology. This study innovatively designs the automatic lifting system of the bogie and the docking part of the vehicle, introduces the automatic guidance technology and the remote-control technology to optimize the car body structure, and uses the SAP software to carry out the finite element analysis of the car body load capacity and Flexsim software to carry out the simulation analysis on the operation of vehicles. The designed transfer vehicle can improve the transfer efficiency of ocean port containers, reduce the transit time of field and station equipment and container transport links, and improve the level of multimodal transport and comprehensive economic benefits.
    Źródło:
    Polish Maritime Research; 2018, S 3; 5-12
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Image fusion for travel time tomography inversion
    Autorzy:
    Yin, X.
    Liu, L.
    Zhao, X.
    Ashraf, M. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/259784.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    tomography
    inversion algorithm
    wavelet transform
    image fusion
    Opis:
    The travel time tomography technology had achieved wide application, the hinge of tomography was inversion algorithm, the ray path tracing technology had a great impact on the inversion results. In order to improve the SNR of inversion image, comprehensive utilization of inversion results with different ray tracing can be used. We presented an imaging fusion method based on improved Wilkinson iteration method. Firstly, the shortest path method and the linear travel time interpolation were used for forward calculation; then combined the improved Wilkinson iteration method with super relaxation precondition method to reduce the condition number of matrix and accelerate iterative speed, the precise integration method was used to solve the inverse matrix more precisely in tomography inversion process; finally, use wavelet transform for image fusion, obtain the final image. Therefore, the ill- conditioned linear equations were changed into iterative normal system through two times of treatment and using images with different forward algorithms for image fusion, it reduced the influence effect of measurement error on imaging. Simulation results showed that, this method can eliminate the artifacts in images effectively, it had extensive practical significance.
    Źródło:
    Polish Maritime Research; 2015, S 1; 149-156
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Path following control of the underactuated USV based on the improved line-of-sight guidance algorithm
    Autorzy:
    Liu, T.
    Dong, Z.
    Du, H.
    Song, L.
    Mao, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/259559.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    unmanned surface vessel (USV)
    path following control
    Serret-Frenet coordinate frame
    underactuated system
    improved lineof-sight guidance algorithm
    nonlinear backstepping method
    Opis:
    The path following control problem of the underactuated unmanned surface vessel (USV) is studied in this paper. An improved line-of-sight (LOS) guidance algorithm is proposed which can adjust adaptively based on the path following error. The global asymptotically stable path following controller is designed based on the nonlinear backstepping method and the Lyapunov stability theory. Firstly, the USV path following error model is established in the Serret-Frenet (SF) coordinate frame. The path following error in the inertial coordinate frame is transformed into the SF coordinate frame, which is used to define the path following control problem. Secondly, inspired by the traditional LOS guidance algorithm, the longitudinal path following error in the SF coordinate frame is introduced into the improved LOS guidance algorithm. This allows the algorithm to adjust adaptively to the desired path. Thirdly, in order to solve the underactuated problem of the USV path following control system, the tangential velocity of the desired path is designed as a virtual input. The underactuated problem is converted to a virtual fully actuated problem by designing the virtual control law for the tangential velocity. Finally, by combining backstepping design principles and the Lyapunov stability theory, the longitudinal thrust control law and the yaw torque control law are designed for the underactuated USV. Meanwhile, the global asymptotic stability of the path following error is proved. Simulation experiments demonstrate the effectiveness and reliability of the improved LOS guidance algorithm and the path following controller.
    Źródło:
    Polish Maritime Research; 2017, 1; 3-11
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Semi-analytical solution of optimization on moon-pool shaped WEC
    Autorzy:
    Zhang, W. C.
    Liu, H. X.
    Zhang, X. W.
    Zhang, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/963397.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    wave energy
    eigenfunction expansion
    moon pool
    conversion ability
    optimization
    Opis:
    In order to effectively extract and maximize the energy from ocean waves, a new kind of oscillating-body WEC (wave energy converter) with moon pool has been put forward. The main emphasis in this paper is placed on inserting the damping into the equation of heaving motion applied for a complex wave energy converter and expressions for velocity potential added mass, damping coefficients associated with exciting forces were derived by using eigenfunction expansion matching method. By using surface-wave hydrodynamics, the exact theoretical conditions were solved to allow the maximum energy to be absorbed from regular waves. To optimize the ability of the wave energy conversion, oscillating system models under different radius-ratios are calculated and comparatively analyzed. Numerical calculations indicated that the capture width reaches the maximum in the vicinity of the natural frequency and the new kind of oscillating-body WEC has a positive ability of wave energy conversion.
    Źródło:
    Polish Maritime Research; 2016, S 1; 25-31
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal configurations of wave energy converter arrays with a floating body
    Autorzy:
    Zhang, W.
    Liu, H.
    Zhang, X.
    Zhang, L.
    Ashraf, M. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/260084.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    wave energy
    cylinder array
    power take-off
    hydrodynamic analysis
    Opis:
    An array of floating point-absorbing wave energy converters (WECs) is usually employed for extracting efficiently ocean wave energy. For deep water environment, it is more feasible and convenient to connect the absorbers array with a floating body, such as a semi-submersible bottom-moored disk, whose function is to act as the virtual seabed. In the present work, an array of identical floating symmetrically distributed cylinders in a coaxial moored disk as a wave energy device is proposed The power take-off (PTO) system in the wave energy device is assumed to be composed of a linear/nonlinear damper activated by the buoys heaving motion. Hydrodynamic analysis of the examined floating system is implemented in frequency domain. Hydrodynamic interferences between the oscillating bodies are accounted for in the corresponding coupled equations. The array layouts under the constraint of the disk, incidence wave directions, separating distance between the absorbers and the PTO damping are considered to optimize this kind of WECs. Numerical results with regular waves are presented and discussed for the axisymmetric system utilizing heave mode with these interaction factors, in terms of a specific numbers of cylinders and expected power production.
    Źródło:
    Polish Maritime Research; 2016, S 1; 71-77
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An improved feature extraction method for rolling bearing fault diagnosis based on MEMD and PE
    Autorzy:
    Zhang, H.
    Zhao, L.
    Liu, Q.
    Luo, J.
    Wei, Q.
    Zhou, Z.
    Qu, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/259770.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    improved feature extraction method
    rolling bearing fault diagnosis
    MEMD
    PE
    Opis:
    The health condition of rolling bearing can directly influence to the efficiency and lifecycle of rotating machinery, thus monitoring and diagnosing the faults of rolling bearing is of great importance. Unfortunately, vibration signals of rolling bearing are usually overwhelmed by external noise, so the fault frequencies of rolling bearing cannot be readily obtained. In this paper, an improved feature extraction method called IMFs_PE, which combines the multivariate empirical mode decomposition with the permutation entropy, is proposed to extract fault frequencies from the noisy bearing vibration signals. First, the raw bearing vibration signals are filtered by an optimal band-pass filter determined by SK to remove the irrelative noise which is not in the same frequency band of fault frequencies. Then the filtered signals are processed by the IMFs_PE to get rid of the relative noise which is in the same frequency band of fault frequencies. Finally, a frequency domain condition indicator FFR(Fault Frequency Ratio), which measures the magnitude of fault frequencies in frequency domain, is calculated to compare the effectiveness of the feature extraction methods. The feature extraction method proposed in this paper has advantages of removing both irrelative noise and relative noise over other feature extraction methods. The effectiveness of the proposed method is validated by simulated and experimental bearing signals. And the results are shown that the proposed method outperforms other state of the art algorithms with regards to fault feature extraction of rolling bearing.
    Źródło:
    Polish Maritime Research; 2018, S 2; 98-106
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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