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Solution space analysis of Double Lunar-Swingby periodic trajectory

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Science china(Technological Sciences) 2010年第8期53卷 2081-2088页

作者： LUO ZongFu ,MENG YunHe&TANG GuoJian college of aerospace and material engineering,national university of defense technology,changsha 410073,china 1. college of aerospace and material engineering National University of Defense Technology Changsha 410073 China

The Double Lunar-Swingby(DLS)periodic trajectory is a type of large-scale trajectory in Restricted Three-Body Problem ***,the principium of the DLS periodic trajectory is studied,and a preliminary design of the DLS trajectory is developed by the Patched Conic ***,the solution space of the DLS periodic trajectory is discussed in detail and in combination with numerical simulation,a distribution about orbital parameter relationship in the solution space is ***,the variations of the orbital elements with different rotation angular velocities of geocentric apsidal line are found,and two typical orbits are given according to three reference *** is shown that Patched Conic method is feasible for the DLS periodic trajectory solution space analysis,and the conclusions will be valuable to the deep-space exploration orbit design in future.

关键词： Double Lunar-Swingby patched conics solution space analysis orbit design periodic orbit

An experimental study of aero-optical aberration and dithering of supersonic mixing layer via BOS

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Science china(Physics,Mechanics & Astronomy) 2010年第1期53卷 81-94页

作者： ZHAO YuXin , YI ShiHe, TIAN LiFeng, HE Lin & CHENG ZhongYu college of aerospace and material engineering, national university of defense technology, changsha 410073, china 1. college of aerospace and material engineering National University of Defense Technology Changsha 410073 China

The optical performance of supersonic mixing layer is heavily deteriorated by the aero-optical aberration and dithering of coherent structures, but current measuring methods limit the spatiotemporal resolution in relevant studies. A high resolution whole-field aero-optical aberration and dithering measuring method based on the Background Orient Schlieren (BOS) technique was studied. The systematic structure, sensitivity and resolution of BOS are analyzed in this paper. The aero-optical aberration and dithering of streamwise structures in supersonic mixing layers were quantificationally studied with BOS. The aberration field of spanwise structures revealed the ribbon-like aberration structures, which heavily restrict the optical performance of a mixing layer. The quantifications of aero-optical aberration and dithering are very important in studying aero-optical performance of supersonic mixing layer.

关键词： aero-optics supersonic mixing layer BOS

Review on abort trajectory for manned lunar landing mission

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Science china(Technological Sciences) 2010年第10期53卷 2691-2698页

作者： XI XiaoNing1, HUANG WenDe2 & WANG Wei2,3 1 college of Mechatronics engineering and Automation, national university of defense technology, changsha 410073, china 2.college of aerospace and material engineering, national university of defense technology, changsha 410073, china 3 School of Surveying and Spatial Information System, university of New South Wales, Sydney, NSW 2052, Australia 1. college of Mechatronics engineering and Automation National University of Defense Technology Changsha 410073 China2. College of Aerospace and Material Engineering National University of Defense Technology Changsha 410073 China3. School of Surveying and Spatial Information System University of New South Wales Sydney NSW 2052 Australia

Abort trajectory is a passage that ensures the astronauts to return safely to the earth when an emergency occurs. Firstly,the essential elements of mission abort are analyzed entirely based on summarizing the existing studies. Then,abort trajectory requirement and rational selection for different flight phases of typical manned lunar mission are discussed specifically. Considering a trade-off between the two primary constrains of an abort,the return time of flight and energy requirement,a general optimizing method for mission abort is proposed. Finally,some suggestions are given for china’s future manned lunar landing mission.

关键词： manned lunar landing mission abort trajectory design free return trajectory

Multiresolution analysis of density fluctuation in supersonic mixing layer

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Science china(Technological Sciences) 2010年第2期53卷 584-591页

作者： ZHAO YuXin1, YI ShiHe, TIAN LiFeng, HE Lin & CHENG ZhongYu college of aerospace and material engineering, national university of defense technology, changsha 410073, china 1. college of aerospace and material engineering National University of Defense Technology Changsha 410073 China

Due to the difficulties in measuring supersonic density field, the multiresolution analysis of supersonic mixing layer based on experimental images is still a formidable challenge. By utilizing the recently developed nanoparticle based planar laser scattering method, the density field of a supersonic mixing layer was measured at high spatiotemporal resolution. According to the dynamic behavior of coherent structures, the multiresolution characteristics of density fluctuation signals and density field images were studied based on Taylor’s hypothesis of space-time conversion and wavelet analysis. The wavelet coefficients reflect the characteristics of density fluctuation signals at different scales, and the detailed coefficients reflect the differences of approximation at adjacent levels. The density fluctuation signals of supersonic mixing layer differ from the periodic sine signal and exhibit similarity to the fractal Koch signal. The similarity at different scales reveals the fractal characteristic of mixing layer flowfield. The two-dimensional wavelet decomposition and reconstruction of density field images extract the approximate and detailed signals at different scales, which effectively resolve the characteristic structures of the flowfield at different scales.

关键词： supersonic mixing layer density fluctuation multiresolution analysis

An algorithm for high precision attitude determination when using low precision sensors

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Science china(Information Sciences) 2012年第3期55卷 626-637页

作者： CAO Lu , CHEN XiaoQian & SHENG Tao college of aerospace and materials engineering national university of defense technology, changsha 410073, china 1. college of aerospace and materials engineering national university of defense technology Changsha 410073 China

The technology for high precision attitude determination when using low precision sensors is a key requirement of a modern small satellite. This paper presents a new attitude determination algorithm termed preprocess EKF(PP-EKF) based on preprocessing of the sensor data. It can enhance the overall modeling accuracy by using the quadratic penalty function to correct the dynamic model error and angular velocity error in realtime, based on the information fusion of the current and the past measurement information. The measurement model of the EKF is linearized by introducing the q method. The solution error of this process is also corrected to further improve the accuracy of the measurement model and make better use of measurement data from the low precision sensors, to obtain good attitude determination results. Finally, the simulation results demonstrate the high reliability and other advantages of the proposed algorithm.

关键词： attitude determination EKF small satellite information fusion

Synthetically adaptive robust filtering for satellite orbit determination

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Science china Earth Sciences 2004年第7期47卷 585-592页

作者： YANG Yuanxi1 & WEN Yuanlan2 1. Xi’an Research Institute of Surveying and Mapping, Xi抋’an 710054, china 2. college of aerospace and material engineering, national university of defense technology, changsha 410073, china 1. Xi’an Research Institute of Surveying and Mapping 710054 Xi’an China 2. college of aerospace and material engineering National University of Defense Technology 410073 Changsha China

The quality of the satellite orbit determination is rested on the knowledge of per-turbing forces acting on the satellite and stochastic properties of the observations, and the ability of controlling various kinds of errors. After a brief discussion on the dynamic and geometric orbit determinations, Sage adaptive filtering and robust filtering are reviewed. A new synthetically adaptive robust filtering based on a combination of robust filtering and Sage filtering is *** is shown, by derivations and calculations, that the synthetically adaptive robust filtering for orbit determination is not only robust but also simple in calculation. It controls the effects of the outliers of tracking observations and the satellite dynamical disturbance on the parameter esti-mates of the satellite orbit.

关键词： satellite orbit, Sage filtering, adaptive orbit determination, robust estimation.

Phugoid dynamic characteristic of hypersonic gliding vehicles

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Science china(Information Sciences) 2011年第3期54卷 542-550页

作者： CHEN XiaoQing, HOU ZhongXi, LIU JianXia & CHEN XiaoQian college of aerospace and materials engineering, national university of defense technology, changsha 410073, china 1. college of aerospace and materials engineering National University of Defense Technology Changsha 410073 China

This paper focuses on the phugoid dynamic characteristic of hypersonic gliding vehicle. By regarding equilibrium glide as the fixed state of reentry trajectory, the dynamic equations are simplified and a hyper-geometric equation with a forcing function is deduced. Linearization theory is applied to analyze the characteristic of the motion, and the phugoid mode is found to be stable. An analytical solution of flight path angle as a function of speed is derived based on General Multiple Scale theory. The dynamic characteristic is analyzed, and the analytic solution is found to be in good agreement with the numerical simulation. When the initial states do not satisfy equilibrium glide condition or perturbation occurs, a damped oscillation along the equilibrium glide trajectory would occur. The damping diminishes as the speed decreases. The number of oscillations is decided by the lift-to-drag ratio, the initial altitude and the initial/final speed.

关键词： hypersonic gliding vehicle phugoid dynamics equilibrium glide general multiple scale theory

A new navigation approach of terrain contour matching based on 3-D terrain reconstruction from onboard image sequence

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Science china(Technological Sciences) 2010年第5期53卷 1176-1183页

作者： LI LiChun1,2,YU QiFeng2,SHANG Yang2,YUAN Yun2,LU HongWei3 & LIU XiaoLin4 1 Beijing aerospace Control Center,Beijing 100094,china 2.college of aerospace and material engineering,national university of defense technology,changsha 410073,china 3 Equipment Research Institute of PLA’s Second Artillery,Beijing 100085,china 4 college of Mechatronic engineering and Automation,national university of defense technology,changsha 410073,china 1. Beijing aerospace Control Center Beijing 100094 China2. College of Aerospace and Material Engineering National University of Defense Technology Changsha 410073 China3. Equipment Research Institute of PLA’s Second Artillery Beijing 100085 China4. College of Mechatronic Engineering and Automation National University of Defense Technology Changsha 410073 China

This article presents a passive navigation method of terrain contour matching by reconstructing the 3-D terrain from the image sequence(acquired by the onboard camera).To achieve automation and simultaneity of the image sequence processing for navigation,a correspondence registration method based on control points tracking is proposed which tracks the sparse control points through the whole image sequence and uses them as correspondence in the relation geometry ***,a key frame selection method based on the images overlapping ratio and intersecting angles is explored,thereafter the requirement for the camera system configuration is *** proposed method also includes an optimal local homography estimating algorithm according to the control points,which helps correctly predict points to be matched and their speed ***,the real-time 3-D terrain of the trajectory thus reconstructed is matched with the referenced terrain map,and the result of which provides navigating *** digital simulation experiment and the real image based experiment have verified the proposed method.

关键词： terrain contour matching vision-based navigation 3-D reconstruction control points key frame registration optimal local homography

Rheological Behaviors and Processing Windows of Low Viscosity Epoxy Resin for VIMP

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Journal of Wuhan university of technology(materials Science) 2011年第5期26卷 931-934页

作者：刘卓峰 college of aerospace and material engineering National University of Defense Technology

The chemorheological behaviors of a low viscosity epoxy resin system （Huntsman 1564/3486） for vacuum infusion moulding process （VIMP） were studied with viscosity *** dual-Arrhenius rheological model and the engineering viscosity model were established and compared with the experimental *** result showed that the viscosity in the earlier stage calculated by dual-Arrhenius model were smaller than the experimental data,while the data calculated by the engineering model were *** the two models together can predict the rheological behaviors of the resin system in a more credible *** processing windows of the resin system for VIMP were determined based on the two *** optimum processing temperature is 30-45 ℃.

关键词： vacuum infusion molding process(VIMP) epoxy resin rheological behaviors