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Adaptive control for autonomous rendezvous of spacecraft on elliptical orbit

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Acta Mechanica Sinica 2009年第4期25卷 539-545页

作者： Shan lu Shijie Xu school of astronautics, {3.,{3. beijing, China school of astronautics Beihang University 100191 Beijing China

A strategy for spacecraft autonomous rendezvous on an elliptical orbit in situation of no orbit information is developed. Lawden equation is used to describe relative motion of two spacecraft. Then an adaptive gain factor is introduced, and an adaptive control law for auton- omous rendezvous on the elliptical orbit is designed using Lyapunov approach. The relative motion is proved to be ultimately bounded under this control law, and the final relative position error can achieve the expected magnitude. Simulation results indicate that the adaptive control law can realize autonomous rendezvous on the elliptical orbit with relative state information only.

关键词： Autonomous rendezvous Elliptical orbit Lyapunov approach Adaptive control Gain factor

The anisotropy of suprathermal electrons in the Martian ionosphere

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Earth and Planetary Physics 2024年第3期8卷 459-471页

作者： YuTian Cao Jun Cui XiaoShu Wu WenJun Liang RuiQi Fu haoyu lu Planetary Environmental and Astrobiological Research Laboratory(PEARL) School of Atmospheric SciencesSun Yat-sen UniversityZhuhai 519082China Key Laboratory of Geospace Environment University of Science&Technology of ChinaChinese Academy of SciencesHefei 230026China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China school of Space and Environment Beihang UniversityBeijing 102206China

Suprathermal electrons are an important population of the Martian ionosphere, either produced by photoionization of atmospheric neutrals or supplied from the Solar Wind (SW). This study is dedicated to an in-depth investigation of the pitch angle distribution of suprathermal electrons at two representative energies, 19−55 eV and 124−3.6 eV, using the extensive measurements made by the Solar Wind Electron Analyzer on board the Mars Atmosphere and Volatile Evolution. Throughout the study, we focus on the overall degree of anisotropy, defined as the standard deviation of suprathermal electron intensity among different directions which is normalized by the mean omni-directional intensity. The available data reveal the following characteristics: (1) In general, low energy electrons are more isotropic than high energy electrons, and dayside electrons are more isotropic than nightside electrons;(2) On the dayside, the anisotropy increases with increasing altitude at low energies but remains roughly constant at high energies, whereas on the nightside, the anisotropy decreases with increasing altitude at all energies;(3. Electrons tend to be more isotropic in strongly magnetized regions than in weakly magnetized regions, especially on the nightside. These observations indicate that the anisotropy is a useful diagnostic of suprathermal electron transport, for which the conversion between the parallel and perpendicular momenta as required by the conservation of the first adiabatic invariant, along with the atmospheric absorption at low altitudes, are two crucial factors modulating the observed variation of the anisotropy. Our analysis also highlights the different roles on the observed anisotropy exerted by suprathermal electrons of different origins.

关键词： Mars ionosphere suprathermal electron pitch angle distribution

Bursting of Morris-Lecar neuronal model with current-feedback control

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Science China(Technological Sciences) 2009年第3期52卷 771-781页

作者： DUAN LiXia1, lu QiShao2 & CHENG DaiZhan3.1 College of Science, North China university of Technology, beijing 100144, China 2 {3. of Science, beijing university of Aeronautics and astronautics, beijing 100191, China 3.Institute of Systems Science, Chinese Academy of Sciences, beijing 100190, China College of Science North China University of Technology Beijing 100144 China school of Science Beijing University of Aeronautics and Astronautics Beijing 100191 China Institute of Systems Science Chinese Academy of Sciences Beijing 100190 China

The Morris-Lecar (ML) neuronal model with current-feedback control is considered as a typical fast-slow dynamical system to study the combined influences of the reversal potential VCa of Ca2+ and the feedback current I on the generation and transition of different bursting oscillations. Two-parameter bifurcation analysis of the fast subsystem is performed in the parameter (I, VCa)-plane at first. Three important codimension-2 bifurcation points and some codimension-1 bifurcation curves are obtained which enable one to determine the parameter regions for different types of bursting. Next, we further divide the control parameter (V0, VCa)-plane into five different bursting regions, namely, the "fold/fold" bursting region R1, the "fold/Hopf" bursting region R2, the "fold/homoclinic" bursting region R3. the "subHopf/homoclinic" bursting region R4 and the "subHopf/subHopf" bursting region R5, as well as a silence region R6. Codimension-1 and -2 bifurcations are responsible for explanation of transition mechanisms between different types of bursting. The results are instructive for further understanding the dynamical behavior and mechanisms of complex firing activities and information processing in biological nervous systems.

关键词： neuron bursting bifurcation fast-slow dynamics analysis codimension

Boosting rate performance of layered lithium-rich cathode materials by oxygen vacancy induced surface multicomponent integration

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Journal of Energy Chemistry 2024年第5期92卷 250-262页

作者： Youyou Fang Yuefeng Su Jinyang Dong Jiayu Zhao haoyu Wang Yun lu Bin Zhang Hua Yan Feng Wu Lai Chen beijing Key Laboratory of Environmental Science and Engineering School of Material Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Chongqing Innovation Center Beijing Institute of TechnologyChongqing 401120China Yibin Libode New Materials Co. Ltd.Yibin 64400SichuanChina school of Metallurgy and Environment Central South UniversityChangsha 410083HunanChina Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South UniversityChangsha 410083HunanChina

The rapid development of electric vehicles and portable energy storage systems demands improvements in the energy density and cost-effectiveness of lithium-ion batteries,a domain in which Lithium-rich layered cathode(LLO)materials inherently ***,these materials face practical challenges,such as low initial Coulombic efficiency,inferior cycle/rate performance,and voltage decline during cycling,which limit practical *** study introduces a surface multi-component integration strategy that incorporates oxygen vacancies into the pristine LLO material Li1.2Mn_(0.6)Ni_(0.2)O_(2).This process involves a brief citric acid treatment followed by calcination,aiming to explore rate-dependent degradation *** induced surface oxygen vacancies can reduce surface oxygen partial pressure and diminish the generation of O_(2)and other highly reactive oxygen species on the surface,thereby facilitating the activation of Li ions trapped in tetrahedral sites while overcoming transport ***,the formation of a spinel-like phase with 3. Li+diffusion channels significantly improves Li^(+)diffusion kinetics and stabilizes the surface *** optimally modified sample boasts a discharge capacity of 299.5 mA h g^(-1)at a 0.1 C and 251.6 mA h g^(-1)at a 1 C during the initial activation cycle,with an impressive capacity of 222.1 mA h g^(-1)at a 5 *** notably,it retained nearly 70%of its capacity after 3.0 cycles at this elevated *** straightforward,effective,and highly viable modification strategy provides a crucial resolution for overcoming challenges associated with LLO materials,making them more suitable for practical application.

关键词： Lithium-ion battery Layered lithium rich cathode Surface multicomponent integration Rate-dependent degradation and Li^(+) diffusion kinetics

Reverse reconciliation for continuous variable quantum key distribution

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Science China(Physics,Mechanics & Astronomy) 2010年第1期53卷 100-105页

作者： lu ZhiXin 1,2 , YU Li 1,2 , LI Kang 1,2 , LIU BingCan 1,2,3., LIN JianGui 1,2 , JIAO RongZhen 1,2 & YANG BoJun 1,21 school of Science, beijing {3. of Posts and Telecommunications, beijing 100876, China 2 Key Laboratory of Information Photonics and Optical Communication, Ministry of Education, beijing {3. of Posts and Telecommunications, beijing 100876, China 3.Department of Fundamental Courses, Academy of Armored Force Engineering, beijing 100072, China 1. school of Science Beijing University of Posts and Telecommunications Beijing 100876 China2. Key Laboratory of Information Photonics and Optical Communication Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China3. Department of Fundamental Courses Academy of Armored Force Engineering Beijing 100072 China

An efficient and practical post-processing technique based on reverse reconciliation for continuous variable quantum key distribution is proposed and simulated with low-density parity check (LDPC) codes. MultiLevel Coding/ MultiStage Decoding, which fully utilizes optimization technique such as vector quantization and iterative decoding and the optimal channel coding most close to the Shannon limit, was used to realize efficient reverse reconciliation algorithm. Simulation results showed that the proposed method can improve the secure key distribution rate to 2.2 kb/s and the coding efficiency to 0.89 over 20 km in single-mode optical fiber. Moreover, there still is room for much improvement.

关键词： quantum communication key distribution reverses reconciliation low-density parity check codes

Spin-glass like behaviors in La_(1-x)Tb_xMnO_3.perovskite

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Science China(Physics,Mechanics & Astronomy) 2009年第12期52卷 1893-1897页

作者： ZHANG YingTang1,2,3.WANG ChunChang2,4,LIU WeiBin1,WANG Zhong3.lu HuiBin2 & CHEN ZiYu1 1 Department of Physics,beijing university of Aeronautics and {3.,{3. 2 Institute of Physics & Center for Condensed Matter Physics,Chinese Academy of Sciences,beijing 100190 3.school of Material Science & Engineering,Shaanxi university of Technology,Hanzhong 723.03.4 Institute of Superconducting and Electronic Materials,Wollongong university,Northfield Ave,Gwynneville,NSW 2522,Australia 1. Department of Physics Beijing University of Aeronautics and Astronautics Beijing 100191 China 2. Institute of Physics & Center for Condensed Matter Physics Chinese Academy of Sciences Beijing 100190 China 3. school of Material Science & Engineering Shaanxi University of Technology Hanzhong 723003 China 4. Institute of Superconducting and Electronic Materials Wollongong University Northfield Ave Gwynneville NSW 2522 Australia

A series of samples of La1-xTbxMnO3.(0≤x≤0.15) are prepared. The static and dynamic magnetizations of La1-xTbxMnO3.have been investigated. The results indicate that the spins with the short-range order are frozen into random direction at low enough temperatures which leads to the samples exhibiting the spin-glass like behavior. It is considered that the spin-glass like behavior originates from the competition between ferromagnetic double exchange among Mn3. and Mn2+ and antiferromagnetic superex-change among Mn3. and Mn3.,as well as Tb3. and Tb3..

关键词： La1-xTbxMnO3 spin-glass-like behavior short-range order

Analysis and simulation of high strain compression of anisotropic open-cell elastic foams

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Science China(Technological Sciences) 2010年第3期53卷 863-869页

作者： lu ZiXing,HUANG JiXiang&CHEN Xin school of Aeronautic Science and Engineering,beijing {3. of Aeronautics and {3.,beijing 100191,China 1. school of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China

By elongating the regular Kelvin model in one direction and keeping unchanged in the other two directions,the anisotropic model was ***,the simplified periodic structural cell was obtained according to the periodicity and symmetry of the model in the whole *** the half-strut element and elastic deflection theory to analyze the mechanical behavior as were adopted in the previous studies,this paper obtained the theoretical expressions for the compressive stress and strain as well as the corresponding curves in the rise and transverse *** addition,the theoretical results were examined by the finite element *** indicated that the theoretical analysis was very close to the finite element simulation when the strain was not too high,which confirmed the validity of theoretical *** the same time,the anisotropy was shown to have a significant effect on the mechanical properties of open-cell *** the anisotropy ratio increased,the compressive stress was improved in the rise direction but dropped in the transverse direction under the same strain.

关键词： open-cell foams elastic deformation Kelvin model anisotropy finite element

Reduced analysis and confirmatory research on co-adaptability theoretical solution to conflicting events in construction engineering projects

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Science China(Technological Sciences) 2010年第2期53卷 480-485页

作者： HOU XueLiang1 , lu Mei2 & WANG Kai3.1 school of Business Administration, North China Electric Power university, {3. 102206, China 2 Department of Construction Management, Tsinghua university, {3. 100084, China 3.College of Management, {3. Jiaotong university, {3. 100084, China 1. school of Business Administration North China Electric Power University Beijing 102206 China2. Department of Construction Management Tsinghua University Beijing 100084 China3. College of Management Beijing Jiaotong University Beijing 100084 China

The co-adaptability theoretical solution to conflicting events in construction engineering projects has three problems. First, the transformation of constraint conditions of theoretical solution is very difficult in practical engineering applications; second, some coefficients are difficult to be determined; third, there are overfull circular arithmetic operations involved in it. To resolve these problems, a new method to reduce the theoretical solution complications is proposed. By analyzing the operating mechanism of theoretical solution model, redundancies in the theoretical solution can be eliminated, and the ISM mapping with the co-adaptability solution can be set up. Based on this approach, a procedure to solve practical conflicting events in construction projects is established by replacing characteristic variables with mathematic variables. The research results show that the procedure can replace the co-adaptability theoretical solution effectively and solve practical conflicting events in construction projects.

关键词： construction project conflict theoretical solution reduced analysis ISM confirmatory research

Adaptive RBF neural network control of robot with actuator nonlinearities

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控制理论与应用（英文版） 2010年第2期8卷 249-256页

作者： Jinkun LIU, Yu lu (school of Automation Science and Electrical Engineering, beijing {3. of Aeronautics and {3., beijing 100191, China) school of Automation Science and Electrical Engineering Beijing University of Aeronautics and Astronautics Beijing China

In this paper, an adaptive neural network control scheme for robot manipulators with actuator nonlinearities is presented. The control scheme consists of an adaptive neural network controller and an actuator nonlinearities compensator. Since the actuator nonlinearities are usually included in the robot driving motor, a compensator using radial basis function (RBF) network is proposed to estimate the actuator nonlinearities and eliminate their effects. Subsequently, an adaptive neural network controller that neither requires the evaluation of inverse dynamical model nor the time-consuming training process is given. In addition, GL matrix and its product operator are introduced to help prove the stability of the closed control system. Considering the adaptive neural network controller and the RBF network compensator as the whole control scheme, the closed-loop system is proved to be uniformly ultimately bounded (UUB). The whole scheme provides a general procedure to control the robot manipulators with actuator nonlinearities. Simulation results verify the effectiveness of the designed scheme and the theoretical discussion.

关键词： Adaptive control RBF neural network Actuator nonlinearity Robot manipulator Deadzone