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Wang Z.,Beijing Institute of Technology | Chen L.,Beijing Institute of Computer Application | Guo S.,Cranfield University
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering | Year: 2013

This article presents a study on the flow field and aerodynamic characteristics of the propellers and rudders for the design of a small ducted fan aircraft. In the analysis, an equivalent actuation disk was created as a simplified model of the propellers. A momentum source is determined by equivalent actuation disk numerical simulation using ANSYS CFX software based on vortex theory. In addition, the momentum source distribution function for the equivalent actuation disk model is improved by using experimental data. The computational fluid dynamics method in the ANSYS CFX software is then used to simulate the flow field of the propellers slipstream and determine the key aerodynamic and design parameters for the built-up rudders of the aircraft. The improved equivalent actuation disk method is validated by using the mixing plane method and their results show a good comparison. The simulation and analysis results provide the basis for optimal design of the built-up rudder arrangement and layout for a small ducted fan aircraft. © IMechE 2012. Source

Kang Y.-M.,Beihang University | Xie W.-D.,Beihang University | Hu J.,Beijing Institute of Computer Application | Huang Q.,Beihang University
Binggong Xuebao/Acta Armamentarii | Year: 2011

The traditional Mean-Shift tracking algorithm is not applied to track a size-changing target effectively due to the fixed band-width of its kernel function. For this reason, a new algorithm is proposed. In each frame, Mean Shift tracking algorithm is employed to get the target location, and then the affine structure between frames is calculated to re-correct the position and size of the target. Different experiments prove that the present method has better stability and robustness than the traditional algorithm. Source

Cai G.,Beijing Institute of Technology | Song J.,Beijing Institute of Technology | Chen X.,Beijing Institute of Computer Application
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering | Year: 2014

An angle-of-attack tracking control system is designed for the hypersonic reentry vehicle, whose aerodynamic parameters vary dramatically during reentry phase. The linear parameter-varying (LPV) theory based on linear fractional transformation (LFT) model (named as LPV-LFT method) is applied to design the controller for hypersonic reentry vehicle. Longitudinal moment trim of the hypersonic reentry vehicle is made along the desired flight trajectory, and a damping feedback loop is firstly designed to improve the system's damping and static stability. Then, the linear dynamics model with damping feedback loop is established in LFT structure and treated as the controlled plant, and a parameter-varying reference model is utilized to guarantee the transient performance. The effectiveness of the proposed angle-of-attack tracking control system is validated through the frequency domain analysis and step response simulations. Finally, the actual angle-of-attack command tracking simulations using the nonlinear time-varying mathematical dynamics model are carried out to verify the accuracy and robustness of the hypersonic reentry vehicle control system. © IMechE 2013 Reprints and permissions: sagepub.co.uk/ journalsPermissions.nav. Source

Zhu M.,Harbin Institute of Technology | Chen Y.,Harbin Institute of Technology | Yang C.,Harbin Institute of Technology | Zhao D.,Beijing Institute of Computer Application
Proceedings - 2012 International Conference on Intelligent Systems Design and Engineering Applications, ISDEA 2012 | Year: 2012

A D-PL ( Digital-PL) chaotic model was proposed to construct ATPG (Automatic Test Pattern Generation) of BIST (Built in Self Test) in this paper. The D-PL chaotic model is improvement of the traditional continuous PL chaotic model. The coefficient of power of 2 was used for traditional PL chaos discrete processing. This approach is conducive to the realization of hardware. Shift registers and accumulator adopted to implement iteration avoiding the direct use of the multiplier. This method can effectively reduce the circuits area After parameters optimization, the D-PL chaotic model ATPG was applied for testing digital circuits. Experiment results show that the proposed D-PL chaotic model ATPG has good randomness and ergodicity. The test pattern of D-PL Model has no correlation. It can effectively improve the digital circuits fault detection rate in BIST. © 2012 IEEE. Source

Cai G.,Beijing Institute of Technology | Song J.,Beijing Institute of Technology | Chen X.,Beijing Institute of Computer Application
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering | Year: 2015

The paper addresses the command-tracking-control-system (CTCS) design problem for plants involving continuous and discrete control input simultaneously. A novel approach based on linear matrix inequalities (LMIs) is proposed and demonstrated to the angle-of-attack (AOA) CTCS of hypersonic reentry vehicle (HRV) driven by a hybrid actuator composed of aerosurfaces and reaction control system (RCS). Firstly, the longitudinal nonlinear dynamics model of HRV and the mathematical model of RCS are established, and then the model of the hybrid actuator is described. Secondly, a general command tracking problem is converted to a regulation problem by constructing a deviation system. And the characteristics of the hybrid actuator is considered and modeled definitely based on some modified sector conditions. Then, the CTCS with hybrid actuator is designed by solving a LMIs-based convex optimization problem. Furthermore, the stability performance of the closed-loop CTCS is evaluated and the formulation of the domain of attraction is derived. And the relationship between the size of stability domain and the magnitude of reference command is also discussed. Finally, the proposed approach is applied to the AOA-CTCS of HRV driven by aerosurfaces and RCS, and different sizes and locations of the stability regions are illustrated with different magnitudes of AOA reference command. Validation simulations are carried out by using the longitudinal nonlinear dynamics models of HRV. The research results demonstrate that the proposed LMIs-based approach is well suited for the AOA-CTCS design for HRV driven by aerosurfaces and RCS. © 2014 IMechE. Source

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