Autor: Qi, C. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Bifurcation and chaos analysis of a gear-rotor-bearing system
Autorzy:: Gou, X.
Zhu, L.
Qi, C.
Powiązania:: https://bibliotekanauki.pl/articles/281909.pdf
Data publikacji:: 2018
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: gear-rotor-bearing
dynamics
bifurcation
chaos
Opis:: To study chaos and bifurcation of a gear system, a five-degree-of-freedom nonlinear dynamic model of a gear-rotor-bearing system is established. It consists of a gear pair, supporting shafts, bearings and other auxiliary components. The effects of frequency, backlash, bearing clearance, comprehensive transmission error and stiffness on nonlinear dynamics of the system are investigated according to bifurcation diagrams, phase portraits and Poincar´e maps by a numerical method. Some nonlinear phenomena such as grazing bifurcation, Hopf bifurcation, inverse-Hopf bifurcation, chaos and coexistence of attractors are investigated. Different grazing bifurcations and their causes are discussed. The critical parameters are identified, too.
Źródło:: Journal of Theoretical and Applied Mechanics; 2018, 56, 3; 585-599
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Simultaneous state and parameter estimation based actuator fault detection and diagnosis for an unmanned helicopter
Autorzy:: Wu, C.
Qi, J.
Song, D.
Qi, X.
Han, J.
Powiązania:: https://bibliotekanauki.pl/articles/329847.pdf
Data publikacji:: 2015
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:: actuator fault detection
actuator fault diagnosis
unmanned helicopter
Kalman filter
set membership filter
adaptive scheme
detekcja uszkodzeń
diagnostyka uszkodzeń
śmigłowiec bezzałogowy
filtr Kalmana
Opis:: Simultaneous state and parameter estimation based actuator fault detection and diagnosis (FDD) for single-rotor unmanned helicopters (UHs) is investigated in this paper. A literature review of actuator FDD for UHs is given firstly. Based on actuator healthy coefficients (AHCs), which are introduced to represent actuator faults, a combined dynamic model is established with the augmented state containing both the flight state and AHCs. Then the actuator fault detection and diagnosis problem is transformed into a general nonlinear estimation one: given control inputs and the measured flight state contaminated by measurement noises, estimate both the flight state and AHCs recursively in each time-step, which is also known as the simultaneous state and parameter estimation problem. The estimated AHCs can further be used for fault tolerant control (FTC). Based on the existing widely used nonlinear estimation methods such as the unscented Kalman filter (UKF) and the extended set-membership filter (ESMF), three kinds of adaptive schemes (KF-UKF, MIT-UKF and MIT-ESMF) are proposed by our team to improve the actuator FDD performance. A comprehensive comparative study on these different estimation methods is given in detail to illustrate their advantages and disadvantages when applied to unmanned helicopter actuator FDD.
Źródło:: International Journal of Applied Mathematics and Computer Science; 2015, 25, 1; 175-187
1641-876X
2083-8492
Pojawia się w:: International Journal of Applied Mathematics and Computer Science
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Simulation and Casting Process of Aluminum Alloy Multi-Way Valve Body with Various Gating Systems
Autorzy:: Rong, L.
Lunjun, C.
Ming, S.
Qi, Z.
Yong, L.
Heng, W.
Powiązania:: https://bibliotekanauki.pl/articles/381887.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: casting process
aluminum alloy
valve body
gating system
simulation analysis
proces odlewniczy
stop aluminium
korpus zaworu
układ wlewowy
analiza symulacji
Opis:: In order to study the effects of various gating systems on the casting of a complex aluminum alloyed multi-way valve body, both software simulation analysis and optimization were carried out. Following, the aluminum alloyed multi-way valve body was cast to check the pouring of the aluminum alloy valve body. The computer simulation results demonstrated that compared to the single side casting mode, the casting method of both sides of the gating system would reduce the filling of the external gas, while the air contact time would be lower. Adversely, due to the pouring on both sides, the melt cannot reach at the same time, leading to the liquid metal speed into the cavity to differ, which affected the liquid metal filling stability. The riser unreasonable setting led to the solidification time extension, resulting in a high amount of casting defects during solidification. Also, both gating systems led the entire casting inconsequential solidification. To overcome the latter problems, a straight gate was set at the middle pouring and the horizontal gate diversion occurred on both sides of pouring, which could provide better casting results for the aluminum alloyed multi-valve body.
Źródło:: Archives of Foundry Engineering; 2018, 18, 2; 84-94
1897-3310
2299-2944
Pojawia się w:: Archives of Foundry Engineering
Dostawca treści:: Biblioteka Nauki

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