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Zeng G.,National University of Defense Technology | Hu M.,Academy of Equipment Command and Technology
Acta Astronautica | Year: 2012

The current paper investigates the electromagnetic formation flight control problem using the finite-time control technique. The electromagnetic force model is presented, and the effects of the Earths magnetic field on the EMFF satellites are analyzed. The equations of relative motion and general formation description method are then established. A robust sliding mode controller is designed to achieve trajectory tracking in the presence of model uncertainties and external disturbances. The proposed controller, which combines the advantages of linear and terminal sliding mode controls, can guarantee the convergence of tracking errors in finite time rather than in the asymptotic sense. By constructing a particular Lyapunov function, the closed-loop system is proven globally stable and convergent. Numerical simulations of formation maintenance and reconfiguration are then presented to show the effectiveness of the developed controller. © 2012 Elsevier Ltd. All rights reserved. Source

Zhou J.D.,PLA Air Force Aviation University | Wang X.D.,PLA Air Force Aviation University | Song H.,Academy of Equipment Command and Technology
Pattern Recognition | Year: 2011

Supervised classification based on error-correcting output codes (ECOC) is an efficient method to solve the problem of multi-class classification, and how to get the accurate probability estimation via ECOC is also an attractive research direction. This paper proposed three kinds of ECOC to get unbiased probability estimates, and investigated the corresponding classification performance in depth at the same time. Two evaluating criterions for ECOC that has better classification performance were concluded, which are Bayes consistence and unbiasedness of probability estimation. Experimental results on artificial data sets and UCI data sets validate the correctness of our conclusion. © 2011 Elsevier Ltd. All rights reserved. Source

Ren Y.,Academy of Equipment Command and Technology | Su D.,Beihang University | Fang J.,Beihang University
IEEE Transactions on Power Electronics | Year: 2013

To intuitively analyze the absolute and relative stability of the forward and backward whirling modes of the high-speed magnetically suspended flywheel rotor with significant gyroscopic effects and bending modes, this paper presents a whirling modes stability criterion based on complex coefficient frequency characteristics method. Through variable reconstruction, the multiple-input multiple-output magnetically suspended rotor system is converted into a single-input single-output (SISO) system with complex coefficients. The stability equivalence of the systems before and after variable reconstruction has been proven. Based on this, the inherent relationships between the distribution of the closed-loop poles of the complex coefficient SISO system and the whirling modes stability are revealed, and the Nyquist stability criterion is further extended by applying the argument principle. All of these lay the foundation for the whirling modes stability theorem, and then, their stability criterion is further developed. Simulation and experimental results prove the effectiveness and correctness of the presented criterion. © 1986-2012 IEEE. Source

Hong Y.,Academy of Equipment Command and Technology
Shiyan Liuti Lixue/Journal of Experiments in Fluid Mechanics | Year: 2014

Tunable diode laser absorption spectroscopy (TDLAS), a line-of-sight technology, is used to measure the temperature, velocity, concentration and other parameters in the flow field. As a fast and efficient diagnostic tool, TDLAS sensors have wide applications in the development of the combustion and propulsion system. TDLAS sensors play more and more important role in the improvement of the system performance. When new concept propulsion appears, the sensors face new challenge, at the same time, relevant technology have been improved. The development of the TDLAS technique, applications in the combustion diagnosis and enormous potential have been summarized. This review can provide enlightenment and help for the researchers in this field. Source

Zhang F.,Academy of Equipment Command and Technology
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2016

Through research on the test of coating corrosion damage, this paper finds out that the temperature-time (T-H) curve of coating corrosion and the T-H curve of metallic corrosion are consistent, and they have the same service environment spectrum. Since the calculation formula of metallic calendar life is deduced from the distribution regularities and service environment spectrum of T-H curve, the calculation formula of coating's calendar life is the same as that of the metallic calendar life. It is also revealed that metallic coating is sensitive to test temperature with some regularities. Hence, an effective test method to have the calendar life of coating is to increase the temperature of the test. To verify the above-mentioned conclusion, a comparative study of theoretical calculation and test of the calendar life of aluminum coating is also conducted. © 2016, Press of Chinese Journal of Aeronautics. All right reserved. Source

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