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Application of two special orbits in the orbit determination of lunar satellites

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Research in Astronomy and Astrophysics 2014年第10期14卷 1307-1328页

作者： Peng Liu Xi-Yun Hou Jing-Shi Tang Lin Liu School of Astronomy and space science Nanjing University institute of space Environment and Astrodynamics Nanjing University

Using inter-satellite range data, the combined autonomous orbit determina- tion problem of a lunar satellite and a probe on some special orbits is studied in this paper. The problem is firstly studied in the circular restricted three-body problem, and then generalized to the real force model of the Earth-Moon system. Two kinds of spe- cial orbits are discussed： collinear libration point orbits and distant retrograde orbits. Studies show that the orbit determination accuracy in both cases can reach that of the observations. Some important properties of the system are carefully studied. These findings should be useful in the future engineering implementation of this conceptual study.

关键词： celestial mechanics -- space vehicles -- Moon -- methods numerical

Distribution of charged lunar dust in the south polar region of the moon

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Chinese Physics B 2022年第4期31卷 441-448页

作者： Qing Xia Ming-Hui Cai Liang-Liang Xu Rui-Long Han Tao Yang Jian-Wei Han National space science Center Chinese Academy of SciencesBeijing 100190China School of Astronomy and space science University of Chinese Academy of SciencesBeijing 100049China

Lunar dust is one of the most threatening problems confronting the return of human beings to the *** this work we studied the spatial distribution behavior of charged lunar dust in the solar wind plasma environment in the south polar region of the moon and considered the influence of a mini-crater using spacecraft Plasma interactions *** distribution of dust and plasma at low solar altitude angles of 20°and 0°was studied,and the spatial density of lunar dust was~10^(10.4)m^(-3)and~10^(11.5)m^(-3),*** is because a higher surface potential will result in transportation of small dust particles and photoelectrons can also neutralize positively charged lunar *** dust density in the plasma void region created by a mini-crater with a 5 m high wall was *** obtained a quasi-neutral electric environment in the plasma void region of the mini-crater,and the dust density was about a magnitude lower than that in other *** dust risk to a spacesuit is much lower on the nightside than on the dayside,but there is severe charged lunar dust transport in the region between light and shade,which is dominated by the difference in surface and plasma potential caused by photoelectrons.

关键词： lunar dust south polar region solar wind mini-crater

Secondary electron yield of air-exposed ALD-Al_(2)O_(3) coating on Ag-plated aluminum alloy

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Chinese Physics B 2024年第11期33卷 265-271页

作者： Xue-Man Wan Tian-Cun Hu Jing Yang Na Zhang Yun He Wan-Zhao Cui National Key Laboratory of science and Technology on space Microwave China Academy of Space Technology (Xi'an)Xi'an 710100China

Secondary electron yield(SEY)of air-exposed metals tends to be increased because of air-formed oxide,hydrocarbon,and other *** enhances the possibility of secondary electron multipacting in high-power microwave systems,resulting in undesirable occurrence of discharge ***_(2)O_(3) coatings have been utilized as passive and protective layers on device packages to provide good environmental *** employed atomic layer deposition(ALD)to produce a series of uniform Al_(2)O_(3) coatings with appropriate thickness on Ag-plated aluminum *** secondary electron emission characteristics and their variations during air exposure were *** escape depth of secondary electron needs to exceed the coating thickness to some extent in order to demonstrate SEY of metallic *** on experimental and calculated results,the maximum SEY of Ag-plated aluminum alloy had been maintained at 2.45 over 90 days of exposure without obvious degradation by applying 1 nm Al_(2)O_(3) *** comparison,the peak SEY of untreated Ag-plated aluminum alloy grew from an initial 2.33 to 2.53,exceeding that of the 1 nm Al_(2)O_(3) *** ultra-thin ALDAl_(2)O_(3) coating substantially enhanced the SEY stability of metal materials,with good implications for the environmental dependability of spacecraft microwave components.

关键词： secondary electron yield(SEY) atomic layer deposition air exposure multipactor

Effects of mesoscale gravity waves on sporadic E simulated by a one-dimensional dynamic model

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Earth and Planetary Physics 2025年第1期9卷 1-9页

作者： Xu Zhou ZeZhong Li XinAn Yue LiBo Liu Key Laboratory of Earth and Planetary Physics/Heilongjiang Mohe National Geophysical Observatory/Beijing National Observatory of space Environment Institute of Geology and GeophysicsChinese Academy of Sciences(CAS)Beijing 100029China College of Earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China CAS Center for Excellence in Comparative Planetology/CAS Key Laboratory of Geospace Environment/Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China

in addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively *** this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MiSE-1D(one-dimensional Model of ionospheric Sporadic E),with low numerical dissipation and high *** by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MiSE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower *** effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the *** mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their *** addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.

关键词： sporadic E ion tidal layer gravity waves numerical simulation

Modeling Density and Anisotropy of Energetic Electrons Along Magnetic Field Lines

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Plasma science and Technology 2006年第3期8卷 279-284页

作者：肖伏良冯学尚 Department of Physics and Electronic sciences Changsha University of Science and Technology Changsha 410076 China State Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China State Key Laboratory of space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China

The electromagnetic wave growth or damping depends basically on the number density and anisotropy of energetic particles as the resonant interaction takes place between the particles and waves in the magnetosphere. The variance of both the number density and anisotropy along the magnetic field line is evaluated systematically by modeling four typically prescribed distribution functions. it is shown that in the case of ＂the positive anisotropy＂（namely, the perpendicular temperature T⊥ exceeds the parallel temperature T｜｜）, the number density of energetic electrons always decreases with the magnetic latitude for a regular increasing magnetic field and the maximum wave growth is therefore generally confined to the equator where the resonant energy is minimum, and the number density is the largest. However, the ＂loss-cone＂ anisotropy of the electrons with a ＂pancake＂ distribution or kappa distribution keeps invariant or nearly invariant, whereas the ＂temperature＂ anisotropy with a pure bi-Maxwellian distribution or Ashour-Abdalla and Kennel＇s distributions decreases with the magnetic latitude. The results may provide a useful approach to evaluating the number density and anisotropy of the energetic electrons at latitudes where the observation information is not available.

关键词： number density anisotropy distribution function magnetic field line

Dufour and Soret effects on MHD flow of viscous fluid between radially stretching sheets in porous medium

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Applied Mathematics and Mechanics(English Edition) 2012年第11期33卷 1403-1418页

作者： M. NAWAZ T. HAYAT A. ALSAEDi Department of Humanities and sciences Institute of Space Technology Department of Mathematics Quaid-I-Azam University Department of Mathematics Faculty of Science King Abdulaziz University

The aim of this paper is two-dimensional magnetohydrodynamic viscous fluid bounded by infinite sheets to examine the Dufour and Soret effects on the （MHD） steady flow of an electrically conducting An incompressible viscous fluid fills the porous space. The mathematical analysis is performed in the presence of viscous dissipation, Joule heating, and a first-order chemical reaction. With suitable transformations, the governing partial differential equations through momentum, energy, and concentration laws are transformed into ordinary differential equations. The resulting equations are solved by the homotopy analysis method （HAM）. The convergence of the series solutions is ensured. The effects of the emerging parameters, the skin friction coefficient, the Nusselt number, and the Sherwood number are analyzed on the dimensionless velocities, temperature, and concentration fields.

关键词： magnetohydrodynamic (MHD) flow radial stretching Soret and Dufoureffects porous medium skin friction coefficient

MHD axisymmetric flow of third grade fluid between porous disks with heat transfer

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Applied Mathematics and Mechanics(English Edition) 2012年第6期33卷 749-764页

作者： T.HAYAT A.SHAFiQ M.NAWAZ A.ALSAEDi Department of Mathematics Quaid-i-Azam University Department of Humanities and sciences Institute of Space Technology Department of Mathematics Faculty of ScienceKing Abdulaziz University

The magnetohydrodynamic （MHD） flow of the third grade fluid between two permeable disks with heat transfer is investigated. The governing partial differential equa- tions are converted into the ordinary differential equations by suitable transformations. The transformed equations are solved by the homotopy analysis method （HAM）. The expressions for square residual errors are defined, and the optimal values of convergence- control parameters are selected. The dimensionless velocity and temperature fields are examined for various dimensionless parameters. The skin friction coefficient and the Nus- selt number are tabulated to analyze the effects of dimensionless parameters.

关键词： heat transfer axisymmetric flow third grade fluid porous disk skin fric-tion coefficient Nusselt number

TRACTiVE PERFORMANCE ANALYSiS ON RADiALLY DEPLOYABLE WHEEL CONFiGURATiON OF LUNAR ROVER VEHiCLE BY DiSCRETE ELEMENT METHOD

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Chinese Journal of Mechanical Engineering 2008年第5期21卷 13-18页

作者： Li Wen GAO Feng JiA Yang School of Aeronautic science and Technology Beihang University Beijing 100191 China School of Transportation science and Engineering Beihang University Beijing 100191 China spacecraft System Engineering Division of space science and Deep space Exploration China Academy of Space Technology Institute Beijing 100094 China

With the consideration of volume constraint of launch vehicle and trafficability of rover vehicle on lunar regolith terrain, a new design of radially deployable wheel is presented. For the purpose of achieving the meso-mechanics and dynamical behavior of lunar soil particles as well as macro-parameters of tractive performance for radially deployable wheel, the interaction between two types of wheel configurations and lunar soil particles is analyzed by means of discrete element method. The network of contact forces, the displacement vector chart, and the deformation of lunar soil beneath wheels are plotted. The equations of soil thrust, motion resistance, drawbar pull and driven torque are derived in granular scale based on the coordinates transformation and algebraic summation. The calculated results show that there is sufficient traction for both 6-split and 12-split radially deployable wheels with 304 mm outspread diameter to negotiate lunar regolith terrain specified here; the value of drawbar pull enhances with the increase of split number of radially deployable wheel, however, the required driven torque increases simultaneously, therefore, the tractive efficiency decreases.

关键词： Radially deployable wheel Discrete element method Tractive performance Trafficability Lunar regolith

Oscillation of Quasi-Steady Earth＇s Magnetosphere

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Chinese Physics Letters 2005年第10期22卷 2723-2726页

作者：胡友秋郭孝城李国强王赤黄朝晖 School of Earth and space sciences University of Science and Technology of China Hefei 230026 Center for space science and Applied Research Chinese Academy of Sciences Beijing 100080

A three-dimensional magnetohydrodynamics （MHD） code is designed specially for global simulations of the solar wind-magnetosphere-ionosphere system. The code possesses a high resolution in capturing MHD shocks and discontinuities and a low numerical dissipation in examining possible instabilities inherent in the system. The ionosphere is approximated by a spherical shell with uniform height-integrated conductance. The solar wind is steady, and the interplanetary magnetic field is either due northward or due southward. The code is then run to find solutions of the whole system. it is found that the system has never reached a steady state, but keeps oscillating with a period of about one hour in terms of density variation at the geosynchronous orbit. However, if a certain artificial resistivity is added either in the whole numerical box or in the reconnection sites only, the reconnections change from intermittent to steady regime and the oscillation disappears accordingly. We conclude that the Earth＇s magnetosphere tends to be in a ceaseless oscillation status because of the low dissipation property inherent in the magnetospheric plasma, and the oscillation may be driven by intermittent magnetic reconnections that occur somewhere in the magnetopause and/or the magnetotail.

关键词： iNTERPLANETARY MAGNETiC-FiELD SOLAR-WiND SiMULATiON