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Wyszukujesz frazę "Liu, Li-Wei" wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Nonlinear drift of the spring gravimeter caused by air pressure from the kunming GS15 gravimeters
Autorzy:
Wei, J.
Shen, W.
Li, H.
Liu, Z.
Powiązania:
https://bibliotekanauki.pl/articles/260586.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
GS15 gravimeter meter
air pressure admittance
nonlinear air pressure correction
superconducting gravimeter
Opis:
In order to monitor and correct the meteorological factors of the spring gravity meter, the characteristics of the time varying gravity changes caused by meteorological factors were analyzed. Kunming GS15 gravity meter from 2007 continuous gravity observation has been carried out with the sampling rate of the pressure observation. In this study, we first compare the effects of 4 types of gravity meter and 3 different types of stations on the gravity observed seasonal gravity signals. It is indicated that the observed seasonal gravity signal of the cave is only 1/10, and there is a constant temperature and constant pressure device. Compared with the same time, the gravity signal of the gravity signal is about 100 times smaller. The influence of the pressure load of the gravity meter is tested by using the theory of pressure. The results show that only the actual value of 2cpd - 3cpd pressure load varies from -0.395 to -0.280×10-8ms-2 , and the 1cpd to 1 cpm periodic partial type gravity meter is also in accordance with the law of gravity and air pressure. And with the characteristics of time lag. In this paper, the nonlinear zero drift parameters of the linear regression model with time lag and the time series of the GS15 gravity meter are used to simulate the nonlinear zero drift parameters of the gravity meter. The results show that the gravity signal contains time lag 35 hours, and the air pressure admittance is 0.8 × 10-8ms-2/mbar. The correlation can reach 79%. The gravity changes signal and satellite gravity as well as the gravity water load signal of the land water model are the same as the gravity water load signal in the autumn as the minimum value, and the seasonal variation of the maximum value of gravity in summer.
Źródło:
Polish Maritime Research; 2016, S 1; 180-186
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adptive heading control of underactuated unmanned surface vehicle based on improved backpropagation neural network
Autorzy:
Dong, Zaopeng
Li, Jiakang
Liu, Wei
Zhang, Haisheng
Qi, Shijie
Zhang, Zhengqi
Powiązania:
https://bibliotekanauki.pl/articles/32917278.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
underactuated unmanned surface vehicle
backpropagation neural network controller
heading control
hyperbolic tangent function
Opis:
Aiming at the challenges to the accurate and stable heading control of underactuated unmanned surface vehicles arising from the nonlinear interference caused by the overlay and the interaction of multi interference, and also the uncertainties of model parameters, a heading control algorithm for an underactuated unmanned surface vehicle based on an improved backpropagation neural network is proposed. Based on applying optimization theory to realize that the underactuated unmanned surface vehicle tracks the desired yaw angle and maintains it, the improved momentum of weight is combined with an improved tracking differentiator to improve the robustness of the system and the dynamic property of the control. A hyperbolic tangent function is used to establish the nonlinear mappings an approximate method is adopted to summarize the general mathematical expressions, and the gradient descent method is applied to ensure the convergence. The simulation results show that the proposed algorithm has the advantages of strong robustness, strong anti-interference and high control accuracy. Compared with two commonly used heading control algorithms, the accuracy of the heading control in the complex environment of the proposed algorithm is improved by more than 50%.
Źródło:
Polish Maritime Research; 2023, 1; 54-64
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of water intake layout along the wharf shoreline on ships
Autorzy:
Kong, Xian-wei
Ding, Lei
Liu, Hai-cheng
Qu, Jing
Li, Xiao-song
Powiązania:
https://bibliotekanauki.pl/articles/258971.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
water intake
physical model
numerical model
lateral flow
hydrodynamic force
Opis:
The construction of a water intake along the wharf shoreline can realise the intensive and comprehensive utilisation of the shoreline. However, since the water intake will increase the lateral flow at the wharf and also the hydrodynamic forces on ships, it will bring risks to ships mooring and leaving. The effects of the water intake on ships are studied using a physical model, numerical model and standard formulas. The results show that it leads to an increase of the hydrodynamic forces acting on the ship when the standard formulas are used to calculate the forces without considering the water level difference between the two sides of the ship. The results of the physical model are closer to the real situation. Measures that can effectively reduce the influence of the water intake on ships are proposed by increasing the distance between the wharf front and the front of the water intake as well as the depth of the water inlet windows.
Źródło:
Polish Maritime Research; 2019, 4; 165-171
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
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