2000 Vol. 20, No. 1

Display Method:
MAGNETOHYDRODYNAMIC SIMULATION ON FORMATION OF CORONAL SURGES
ZHENG Human, SU Shoujun, WANG Shui, S. T. Wu
2000, 20(1): 1-9. doi: 10.11728/cjss2000.01.001
Abstract(1865) PDF 634KB(872)
Abstract:
In order to simulating the formation of coronal surges, the characteristics ofmagnetic reconnection caused by the resistive tearing instability in bipole-monopolemagnetic field are studied numerically by using a two-dimensional, time-dependent,compressible magnetohydrodynamic simulation. The results show that the magneticlines of the bipole and monopole fields will reconnect directly and the evolution ofmagnetic field leads to a whip configuration under a magnetostatic basic state whichincludes three regions ── a bipole, a current sheet and a monopole. The upwardplasmoid supported by bended magnetic field diffuses and falls back to solar surfaceafter reaching its maximum height. The upward velocity of plasmoid reaches 0.10vA(vA is Alfven velocity in bipole magnetic field). The simulated result confirms thatthe formation of coronal surges may be related closely to magnetic reconnection inbipole-monopole magnetic field.
EFFECTS OF PRESSURE ANISOTROPY OF SPACE PLASMA ON MAGNETIC RECONNECTION
MA Yingjuan, WANG Shui
2000, 20(1): 10-15. doi: 10.11728/cjss2000.01.010
Abstract(1872) PDF 378KB(660)
Abstract:
The effects of pressure anisotropy on the magnetic reconnection of plasma arestudied based on two-dimensional compressible MHD numerical simulation. It isfound that the growth rate of magnetic reconnection is greatly enhanced in thepresence of a small pressure anistropy (P=1.02P//). This suggests thatmirror instability and tearing instability both affect the developmentof magnetic reconnection. In a pressure anisotropy with (P=1.02P//) tearing mode is restricted and can't form large magneticislands.
EFFECTS OF ELECTRON RING-BEAM ON THE SATELLITE SURFACE POTENTIAL AND PLASMASHEATH
CAO Jinbin, ZHOU Guocheng, WANG Deju, CAI Chunlin
2000, 20(1): 16-22. doi: 10.11728/cjss2000.01.016
Abstract(1631) PDF 458KB(1172)
Abstract:
The effects of electron ring-beam on the satellite surface potential and plasmasheath in magnetized plasma of low earth orbit are studied by means of 21/2-Delectrostatic code. The simulation results show that the satellite is charged negatively when there exists electron beam, and the increase of the density and velocityof electron beams increase the absolute value of satellite negative potential. Whenelectron ring-beams are injected in an oblique angle with respected to the magneticfield, the effects of electron ring-beams decrease when the oblique injection angleincreases from 0° to 90°. The plasma sheath becomes wider when there is electronring-beam and its shape changes from "tear drop" to "fan".
EFFECTS OF NEUTRAL WINDS AND VERTICAL DRIFTS ON LOW-LATITUDE IONOSPHERE
LIU Libo, WAN Weixing, TU Jiannan, BAO Zongti
2000, 20(1): 23-31. doi: 10.11728/cjss2000.01.023
Abstract(1829) PDF 730KB(1507)
Abstract:
Effects of variations of magnitude of E×B vertical drifts and neutral windson low-latitude ionosphere are investigated by using a two-dimensional low-latitudeionospheric time-dependent theoretical model. In the model ion transport equationsare solved by using splitting technique at fixed grid points along magnetic field lines,and densities and velocities of ions are outputted on the given geomagnetic meridian.Modelling results show that the influences of adjusted magnitude of E×B verticaldrifts and neutral winds on low-latitude f0F2 are dependent on magnetic latitudeand local time. And some features not reported previously are also mentioned inthe paper.
THE THEORV OF GPS-BASED GEOMETRIC ORBIT DETERMINATION FOR LOW-EARTH SATELLITES
HU Guorong, OU Jikun
2000, 20(1): 32-39. doi: 10.11728/cjss2000.01.032
Abstract(1529) PDF 632KB(1845)
Abstract:
Methods of single frequency carrier phase-based relative orbit determination(OD) and kinematic network OD for low-earth satellite are developed. From theresults calculated using L1 data collected by GPS/DR onboard Topex/Poseidon,we can draw following conclusions: (a) the accuracy of single frequency carrierphase-based relative OD may attain the order of a few decimeters; (b) the accuracyof relative OD depends on the data quality of ground tracking stations; (c) theaccuracy of kinematic network OD is equavalent to a weighting among relative ODsof different ground tracking stations and can improve the reliability and precisionof OD due to its redundant condition and good geometric configuration.
ALGORITHM STUDY ON AUTONOMOUS ORBIT DETERMINATION FOR LOW EARTH ORBIT MICROSATELLITES USING GPS
SONG Fuxiang, ZUO Wenji
2000, 20(1): 40-47. doi: 10.11728/cjss2000.01.040
Abstract(1734) PDF 585KB(1505)
Abstract:
To realize GPS orbit determination for low earth arbit satellites, a navigationalgorithm called sequential UD covariance factorization algorithm is proposed inthis paper. Formulas of UD algorithm are given completely, and state equationsand measurement equations are derived in detail in the paper. Mathematical modelof the navigation system is built, which is composed of nine state vectors and eightobservation vectors. Finally, numerical simulation experiments are conducted. Simulation results indicate that UD algorithm can not only provide high positioningprecision but also be fit for computers onboard low earth orbit satellites.
SAR MOTION COMPENSATION REQUIREMENT CONCERNING COMPLICATED LINE-OF-SIGHT MOTION ERRORS
CAO Fuxiang, YUAN Jianping
2000, 20(1): 48-53. doi: 10.11728/cjss2000.01.048
Abstract(1617) PDF 344KB(1050)
Abstract:
The working principle of Synthetic Aperture Radar (SAR) based on the knolledge of the relative motion between the vehicle (strictly is Antenna Phase Center)and the target. If the flight path of the vehicle is not accurately known or the SARprocessor is limited in its ability to take the flight data into account, the SAR imagewill be degraded. The purpose of this paper is to study the stripmap SAR MotionCompensation (SARMC) requirement to complicated Line-of-Sight (LOS) motionerrors of flight vehicle and to derive analytical equations of SARMC quantitativerequirement expressed as allowable maximum value of the mainlobe shift, quadraticphase error, cubic phase error and the Integrated Sidelobe Ratio (ISLR).
SATELLITE-NET AUTONOMOUS POSITIONING WITH RELATIVE RANGING
YAN Ye, XI Xiaoning, REN Xuan
2000, 20(1): 54-60. doi: 10.11728/cjss2000.01.054
Abstract(1512) PDF 340KB(1020)
Abstract:
Utilizing relative ranging information for satellite-net autonomous positioningis an effective approach to improve positioning accuracy and relieve ground-burden.A method blending relative ranging data for improving positioning accuracy is givenin this paper. Simulation results indicate that the method is effective.
CONTACT-IMPAC OF SOLAR BATTERY DURING THE DEPLOYMENT OF THE PLATES
LIU Jinyang, HONG Jiazhen
2000, 20(1): 61-68. doi: 10.11728/cjss2000.01.061
Abstract(1773) PDF 566KB(1051)
Abstract:
In this paper, the contact-impact problem of solar battery during the deployment of plates is studied. The equation of motion of flexible multibody systemduring impact is derived. The time histories of impact forces and the accelerationof some nodes of the plates are presented. It shows that the impact forces of thecontact points reach the peak at different time on account of the distortion of theflexible plates. It also shows that when impact occurs, the acceleration of the nodesnear the impact points airs greater than that of the other nodes, and it takes fewtime for the impact wave to spread through the nexible plates. when the impactwave reaches the nodes at the boundary of the outer plate, the acceleration of thenodes becomes greater and vibrant which leads to the swinging of the plates.
CHAOTIC MOTION OF MAGNETIC RIGID SATELLITE IN ORBIT NEAR EQUATORIAL PLANE OF THE EARTH
CHENG Gong, LIU Yanzhu
2000, 20(1): 69-73. doi: 10.11728/cjss2000.01.069
Abstract(1498) PDF 371KB(1536)
Abstract:
The chaotic planar motion of a magnetic rigid satellite in a circular orbit nearthe equatorial plane of the earth is investigated in the present paper. The existenceof chaotic motion of the satellite is predicted by using Melnikov's method and verified by numerical computation in conjunction with the Poincare map. It is shownthat the periodic disturbance of the magnetic field of the earth can cause chaoticmotion of the satellite and the increase of the disturbance can intensify the chaoticmotion.
SPINNING STABILITY OF SPACECRAFT WITH MULTIPLE LIQUID CONTAINERS ON SPINNING AXIS
BAO Guangwei
2000, 20(1): 74-80. doi: 10.11728/cjss2000.01.074
Abstract(1513) PDF 408KB(897)
Abstract:
The spinning stability of a spacecraft with multiple on-axis-containers partiallyfilled with inviscid, incompressible liquids is investigated in this paper. The coupledeffect among translation, nutation of the rigid spacecraft and slosh of the liquidsis considered. Employing Galerkin's method the dynamic system is discretized andthus the dynamic equation is established in ODE form. Using Kelvin's theorem,the stability criterion is finally obtained.K0eywords: Dynamics of spacecraft, Liquid slosh, Stability theory
RESTRAINED VARIABLE STRVCTURE CONTROL FOR A CLASS OF FLEXIBLE SATELLITE
LIU Chunmei, SHEN Yi, HU Hengzhang
2000, 20(1): 81-88. doi: 10.11728/cjss2000.01.081
Abstract(1570) PDF 444KB(1305)
Abstract:
In this paper, a new method for the attitude control of a class of flexible satelliteunder restrained control is presented. The target of the variable structure systemis changed step by step according to the bounded control, which makes the controlinputs under the bound of the execution. Thereby a equivalent unbounded variablestructure control system comes into being which satisfies the reaching condition ofsliding mode.
A METHOD OF FAULT ISOLATION FOR SPACECRAFT BASED ON MINIMUM CUT SETS'RANK
DING Caihong, HUANG Wenhu, JIANG Xingwei
2000, 20(1): 89-94. doi: 10.11728/cjss2000.01.089
Abstract(1648) PDF 332KB(938)
Abstract:
In this paper, the minimum cut sets obtained from fault tree analysis are distinguished and ranked by failure influencing probability in terms of the principle thatthe basic event with its Fussel-Vesely importance nearest to 0.5 could be inspectedfirstly. This method can the occurrence possibility of the top event resulted fromeach minimum cut set, thus, the fault isolation and repair can be achieved so toimprove the diagnostic rate and efficiency.