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Fuzzy adaptive robust control for space robot considering the effect of the gravity

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Chinese Journal of Aeronautics 2014年第6期27卷 1562-1570页

作者： Qin Li Liu Fucai Liang Lihuan Gao Jingfang Key Lab of Industrial Computer Control Engineering of Hebei Province Yanshan University

Space robot is assembled and tested in gravity environment, and completes on-orbit service（OOS） in microgravity environment. The kinematic and dynamic characteristic of the robot will change with the variations of gravity in different working condition. Fully considering the change of kinematic and dynamic models caused by the change of gravity environment, a fuzzy adaptive robust control（FARC） strategy which is adaptive to these model variations is put forward for trajectory tracking control of space robot. A fuzzy algorithm is employed to approximate the nonlinear uncertainties in the model, adaptive laws of the parameters are constructed, and the approximation error is compensated by using a robust control algorithm. The stability of the control system is guaranteed based on the Lyapunov theory and the trajectory tracking control simulation is performed. The simulation results are compared with the proportional plus derivative（PD） controller, and the effectiveness to achieve better trajectory tracking performance under different gravity environment without changing the control parameters and the advantage of the proposed controller are verified.

关键词： Fuzzy adaptive Microgravity Robustness Space robot Trajectory tracking control

Influence of crystal structure and formation energies of impurities (Mg, Zn and Ca) in zinc blende GaN

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中国有色金属学会会刊：英文版 2006年第B2期16卷 854-857页

作者：熊志华江风益万齐欣饶建平 research Center for Luminescence Materials and Devices of Education MinistryNanchang University Nanchang 330047China

First-principles calculations on neutral metal impurities (Mg, Zn and Ca) in zinc blende GaN were studied. Formation energies were calculated for substitution on the gallium site, the nitrogen site and incorporation in the octahedral interstitial site and the tetrahedral interstitial sites. The calculated results show that the major defects studied have a high formation energy in excess of 5 eV, and the gallium substitutional site is favorable for incorporation. MgGa has particularly low formation energy 1.19 eV and can be expected to incorporate readily into GaN. The local crystal structural changes around the impurity in the lattice were studied after metal atoms occupying the gallium substitutional site. It shows that the lattice constant becomes bigger and the tetrahedral angle between impurities and its nearest N atom becomes smaller mainly due to the extended M-N bond length and big size of impurities atoms, which results in a local lattice distortion. The Zn-N (2.04 A) bond strength is the smallest among the three impurities which raises the formation energy. CaGa is unfavorable due to a large size mismatch in spite of a large bond strength (2.25 A). The calculated results identify the two key factors determining impurities incorporation in zinc blende GaN: the atomic size of impurities comparing to that of host atoms and the bond strength between the impurities and its neighbors. The results are in well agreement with other calculated and experimental results.

关键词：闪锌矿型氮化镓杂质晶体结构晶体缺陷形成能

Vapor pressure and thermochemical properties of ZrCl4 for ZrC coating of coated fuel particles

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中国有色金属学会会刊：英文版 2008年第3期18卷 728-732页

作者：刘超刘兵邵友林李自强唐春和 Institute of Nuclear and New Energy technology Tsinghua University

Vapor pressure of zirconium tetrachloride(ZrCl4) under vacuum and an argon pressure of 1×105 Pa was measured. The thermochemical changes of ZrCl4 during evaporation were studied by thermogravimetry-differential thermal analysis(TG-DTA), X-ray diffractometry(XRD), scanning electron microscopy(SEM) and energy-dispersive X-ray(EDX) analysis. At the same temperature, vapor pressures of ZrCl4 under vacuum and an argon pressure of 1×105 Pa are approximately the same. The vapor pressure exceeds 1×105 Pa at 340 ℃, which is high enough for ZrC coating of coated fuel particles. ZrCl4 sample is hydrolyzed to some extent to give ZrO2 and HCl, which however, has little influence on vapor pressure of ZrCl4 at high temperature. No ZrCl3 and Cl2 are produced by decomposition of ZrCl4 during evaporation, which is confirmed by thermodynamic calculation.

关键词：汽压热化学转变 ZrC敷料燃烧颗粒

Kinetics study on leaching of rare earth and aluminum from polishing powder waste using hydrochloric acid

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Journal of Rare Earths 2020年第9期38卷 1009-1018,I0004页

作者： Xitao Wu Zhijian Wang Chuping Xia Xuefeng Shi Tianzong Luo Xinjun Bao Rongli Liu Shengzhong Xie Hunan Rare Earth Metal Material research Institute Changsha 410126China School of Chemistry and Chemical Engineering Central South UniversityChangsha 410083China Hunan Nonferrous Metals Vocational and technical College Zhuzhou 412006China

In this study,a novel hydrometallurgical process consisting of hydrochloric acid three-stage countercurrent leaching and solvent extraction was proposed to recover rare earth oxide(REO)from the rare earth polishing powder waste(REPPW).The effects of HCl concentration,liquid-solid ratio(L/S ratio),temperature and time on the leaching yields of rare earths(in REO)and aluminum(in Al2O3)were *** result shows that the leaching yields of REO and Al2O3 are 90.96%and 43.89%respectively under the optimum leaching parameters of HCl concentration=8.00 mol/L,L/S ratio=4 mL/g,leaching temperature=353 K and leaching time=180 ***,the leaching kinetics of REO and Al2O3 were investigated in this *** leaching behaviors of REO and Al2O3 follow a shrinking sphere/core model and the general leaching process is controlled by the surface chemical *** leaching activation energies of REO and Al2O3 are 9.86 and 13.68 kJ/mol,*** leaching yield of each substance in three-stage countercurrent leaching is improved substantially compared with single-stage leaching,with a change from 90.96%to 95.38%for REO and from 43.89%to 46.22%for Al2O3,***,the total concentration of REO in three-stage countercurrent leaching solution is greatly increased to above 300 g/L,and the acidity of which is decreased to ***=2,which is conducive to subsequent solvent extraction *** purity REO(99.92%)is obtained by solvent extraction separation,oxalate precipitation and *** total recovery yield of REO is 85.13%.

关键词： Rare earth polishing powder waste REPPW Three-stage countercurrent leaching Solvent extraction Kinetics study Thermodynamics

Steam effects over Pd/Ce_(0.67)Zr_(0.33)O_2 three-way catalyst

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Journal of Rare Earths 2011年第3期29卷 217-224页

作者：王建强沈美庆王军王务林 Key Laboratory for Green Chemical technology of State Education Ministry School of Chemical Engineering&TechnologyTianjin University China Automotive technology&research Center State Key Laboratory of Engines Tianjin University

In the purification process of automobile exhaust,existing water plays an important role as an oxidant,which converts CO and hydrocarbons（HCs） by the water-gas shift（WGS） and the steam reforming（SR） reactions,respectively,especially at high *** it is major component of the exhaust which can affect significantly the thermal stability of the three-way *** experiments were carried out close to the real operation conditions（GHSV,concentration,etc.） with a Pd/Ce0.67Zr0.33O2 catalyst supplying information on the CO and C3H8 oxidation reactions in feedstream formed by different reactant *** obtained results showed that the activity of the CO and C3H8 oxidation was promoted by the addition of steam due to the WGS and SR *** WGS and SR reaction were competitive under oxygen-lean *** kinetic analysis was considered for WGS and SR reactions.

关键词： three-way catalysts water-gas shift steam reforming turnover frequency compensation effect rare earths

Digital virtual flight testing and evaluation method for flight characteristics airworthiness compliance of civil aircraft based on HQRM

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Chinese Journal of Aeronautics 2015年第1期28卷 112-120页

作者： Liu Fan Wang Lixin Tan Xiangsheng School of Aeronautic Science and Engineering Beihang University

In order to incorporate airworthiness requirements for flight characteristics into the entire development cycle of electronic flight control system（EFCS） equipped civil aircraft, digital virtual flight testing and evaluation method based on handling qualities rating method（HQRM）is proposed. First, according to HQRM, flight characteristics airworthiness requirements of civil aircraft in EFCS failure states are determined. On this basis, digital virtual flight testing model,comprising flight task digitized model, pilot controlling model, aircraft motion and atmospheric turbulence model, is used to simulate the realistic process of a pilot controlling an airplane to perform assigned flight tasks. According to the simulation results, flight characteristics airworthiness compliance of the airplane can be evaluated relying on the relevant regulations for handling qualities（HQ） rating. Finally, this method is applied to a type of passenger airplane in a typical EFCS failure state, and preliminary conclusions concerning airworthiness compliance are derived quickly. The research results of this manuscript can provide important theoretical reference for EFCS design and actual airworthiness compliance verification of civil aircraft.

关键词： civil aircraft compliance preliminary verification pilot turbulence realistic passenger concerning

Particle flters for probability hypothesis density flter with the presence of unknown measurement noise covariance

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Chinese Journal of Aeronautics 2013年第6期26卷 1517-1523页

作者： Wu Xinhui Huang Gaoming Gao Jun College of Electronic Engineering Naval University of Engineering Automatization of Command Institute Academy of Navy Equipment

In Bayesian multi-target fltering,knowledge of measurement noise variance is very *** mismatches in noise parameters will result in biased *** this paper,a new particle flter for a probability hypothesis density（PHD）flter handling unknown measurement noise variances is *** approach is based on marginalizing the unknown parameters out of the posterior distribution by using variational Bayesian（VB）***,the sequential Monte Carlo method is used to approximate the posterior intensity considering non-linear and non-Gaussian *** other particle flters for this challenging class of PHD flters,the proposed method can adaptively learn the unknown and time-varying noise variances while *** results show that the proposed method improves estimation accuracy in terms of both the number of targets and their states.

关键词： Multi-target tracking(MTT) Parameter estimation Probability hypothesis density Sequential Monte Carlo Variational Bayesian method

Synthesis of nanocrystalline NiCrC alloy feedstock powders for thermal spraying by cryogenic ball milling

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International Journal of Minerals,Metallurgy and Materials 2009年第1期16卷 77-83页

作者： Kai Tao Xiang-lin Zhou Hua Cui Han-bin Chen Yong-bing Li Ji-shan Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Nanocrystalline NiCrC alloy powders with a qualified particle size distribution for thermal spraying were synthesized using the cryogenic ball milling （cryomilling） method. The morphology, microstructure, size distribution, and phase transformation of the powders were characterized by scanning electron microscopy （SEM）, laser scattering for particle size analysis, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. After cryomilling for 20 h, the average grain size of the as-milled powders approached a constant value of 30 nm by XRD measurement. The average particle size slightly increased from 17.5 to 20.3 μm during the 20-h milling. About 90vol% of the powders satisfied the requirement for thermal spraying with the particle dimension of 10-50 μm, and most of the powders exhibited spherical morphology, which were expected to have good fluidity during thermal spraying. The Cr2O3 phase formed during the cryornilling process as revealed in the XRD spectra, which was expected to enhance the thermal stability of the as-milled powders during the followed thermal spraying or other heat treatment.

关键词： cryomilling nanocrystalline feedstock powder particle size distribution nickel chromium alloy

Densification,microstructure,and fracture behavior of TiC/Si_3N_4 composites by spark plasma sintering

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Rare Metals 2008年第3期27卷 315-319页

作者： BAI Ling GE Changchun SHEN Weiping MAO Xiaodong ZHANG Ke Laboratory of Special Ceramics and Powder Metallurgy University of Science and Technology Beijing Beijing 100083 China

TiC/Si3N4 composites were prepared using the β-Si3N4 powder synthesized by self-propagating high-temperature synthesis （SHS） and 35 wt.% TiC by spark plasma sintering. Y2O3 and Al2O3 were added as sintering additives. The almost full sintered density and the highest fracture toughness （8.48 MPa·m1/2） values of Si3N4-based ceramics could be achieved at 1550℃. No interfacial interactions were noticeable between TiC and Si3N4. The toughening mechanisms in TiC/Si3N4 composites were attributed to crack deflection, microcrack toughening, and crack impedance by the periodic compressive stress in the Si3N4 matrix. However, increasing microcracks easily led to excessive connection of microcracks, which would not be beneficial to the strength.

关键词： silicon nitride titanium carbide spark plasma sintering (SPS) microstructure fracture behavior