Yang R.-J.,Nanjing University of Science and Technology |
Yang H.,China North Industries Ltd |
Liang X.-D.,North Heavy Industries Group Corporation Ltd. |
Wang L.-M.,Nanjing University of Science and Technology
Dandao Xuebao/Journal of Ballistics | Year: 2012
To enhance the large-space combat capability for guided projectile(GP), a robust adaptive controller for GP was proposed by combining a parameter estimation scheme with the sliding mode control. Considering the aerodynamic parameter symmetry and cross coupling characteristics of GP, a parametric sliding mode controller was obtained via feedback linearization. The parametric adaptation law was designed based on Lyapunov stability theory, and the adaptive sliding mode controller had strong robustness. Simulation results indicate that the proposed controller is robust with respect to large aerodynamic parametric uncertainty, and has excellent dynamic tracking performance with no control chattering.
Liang F.,Southwest Jiaotong University |
Li F.H.,Southwest Jiaotong University |
Zhang Y.W.,Hebei Hydrology and Engineering Geology Prospecting Institute |
Cui S.A.,Southwest Jiaotong University |
Li J.L.,China North Industries Ltd
Applied Mechanics and Materials | Year: 2013
Based on thermodynamic principles,this paper uses ANSYS to simulate thermal stress of the concrete piers and analyzes the main factors, namely, structure size, concrete strength, boundary conditions and freeze-thaw cycle system which affect thermal stress. We then draw the conclusion that the existence of thermal stress will make the concrete structure undertake cracking risk. Thermal stress difference in massive concrete structures is large and the influence of thermal stress on concrete structures is only limited to a certain size range; thermal stress inside the concrete increases with the increment of concrete strength grade; thermal stress inside the concrete decreases with the increment of boundary constraint conditions; the rate of change of thermal stress increases with the acceleration of freeze-thaw cycles. Meanwhile, we propose that through increasing the thickness of the protective layer and boundary constraint conditions properly, cracking risk of concrete structures can be reduced. © (2013) Trans Tech Publications, Switzerland.
Shi Z.-J.,Beijing Institute of Technology |
Xie H.-Y.,Beijing Institute of Technology |
Lin W.,China North Industries Ltd |
Zhao L.-Y.,Beijing Institute of Technology |
Zhao L.-Y.,Key Laboratory of Dynamics and Control of Flight Vehicle
Guti Huojian Jishu/Journal of Solid Rocket Technology | Year: 2015
The coning motion is a basic angular behavior of spinning missiles, and the research on the stability of coning motion has been the heated topic in the field of spinning missle. The linearized 6-DOF equations of angular motion for a spinning missile with one pair of canards were established in the rolling body frame. The influence of aerodynamic asymmetry due to the canards on the angular motion was revealed via numerical simulations. The analytical stability condition of coning motion was given by Routh criterion, which can be transformed to be an equivalent of rotation rate with stable coning motion. Simulations under different spinning rate demonstrate that the stability condition was reliable. In the case of a given spinning rate, the sinusoidal canard with activating frequency in the neighborhood of the slow mode can induce strong resonance instability. The research results can provide references to the system design, guidance and control design of spinning missiles with one single pair of canards. ©, 2015, Journal of Solid Rocket Technology. All right reserved.
Liu H.-O.,Beijing Institute of Technology |
Jin L.,Beijing Institute of Technology |
Chen J.-B.,China North Industries Ltd
Journal of Beijing Institute of Technology (English Edition) | Year: 2016
In order to improve the shift decision strategy for an off-road vehicle with automated manual transmission (AMT), the generalized road resistance coefficient is defined based on the longitudinal dynamics analysis. Vehicle mass and generalized road resistance coefficient are estimated using the recursive least square (RLS) method with multiple forgetting factors. The improved shift schedule is designed based on the generalized road resistance coefficient under uphill road condition. The simulation and real vehicle test verify the effectiveness of improved shift strategy and the improvement of vehicle dynamic performance. © 2016 Beijing Institute of Technology.
Yang D.-M.,Southwest University of Science and Technology |
Wang Q.-L.,Southwest University of Science and Technology |
Ji H.-X.,Southwest University of Science and Technology |
Xie L.-M.,Southwest University of Science and Technology |
And 2 more authors.
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2012
The γ-LiAlO 2:Tb 3+phosphor was synthesized by citric acid sol-gel method, and its excitation and emission spectra was investigated. γ-LiAlO 2:Tb 3+has several emission peaks, and these are located at 489, 542, 584 and 620 nm, which correspond to the 5D 4→ 7F J, (J=6, 5, 4, 3) transitions of Tb 3+, respectively. The main peak is at 542 nm. The strongest excitation peak at 238 nm of the powder(monitored at an emission wavelength of 542 nm) belongs to the broadband excitation. The effect of amount of Tb 3+ doping content, the charge compensation agent(Li +) on the emission intensity of the γ-LiAlO 2:Tb 3+phosphor were also studied. The results showed that the emission intensity can be controlled by the above factors, and the intensity can be enhanced by selecting the prime optimum conditions.