2004 Vol. 24, No. 2

Display Method:
THE CARRINGTON LONGITUDE DISTRIBUTION OF SOLAR PROTON EVENT SOURCE LOCATIONS DURING 1997-2003
LE Guiming
2004, 24(2): 81-88.
Abstract(1984) PDF 807KB(1025)
Abstract:
There are 78 solar proton events produced in the period from 1997 to 2003. 19 of the total 78 solar proton events haven’t definite source location. In this paper, the Carrington longitude distribution of source location for 59 solar proton events with definite location on the solar surface during 1997-2003 is studied. The results show that the source locations of solar proton events are mainly concentrated in four Carrington longitude bands, namely 10°-453, 135°-155°, 1803-215°, 230°-260°, 265°-310°, 345°-360°. The strongest Carrington longitude band of solar proton event is 265°-310° with 17 solar proton events occurring in the band. The strongest Carrington longitude is 272° with 7 solar proton events occurring on this Carrington longitude. The peak flux for three solar events of the seven solar proton events are over 10000pfu. The known active region 9077 and active region 10486 are located at the Carrington longitude 309° and 283°, respectively. The second strongest Carrington longitude band ranges from 135° to 155°. The Carrington longitude bands 10°-45° and 345°-360° are two moderate strong Carrington longitude bands. There are 28 solar proton events with peak flux over 100 pfu in total during the period from 1997 to 2003. Ten of them occurred in the north hemisphere of the Sun, eighteen of them produced in the southern hemisphere of the Sun. The solar proton events have recurrent law for the same active longitude, the recurrent time gap ranges from several days, 27-day to more than 4-year. Also we find that the solar proton events occurred in two hemispheres by turn for the same active longitude. Because the law of recurrent of the solar proton events not only in time but also in physics is still not very clearly, so that the short term and medium-term prediction of solar proton event are still waited for being solved.
RELATION BETWEEN MAGNETIC SHELL PARAMETER L, Dst AND IMF
CAO Jinbin, YAN Chunxiao, LIU Zhenxing, ZHOU Guocheng
2004, 24(2): 89-95.
Abstract(2218) PDF 682KB(1103)
Abstract:
It is a new trend to use the magnetic coordinate L-Λ. to describe space particle features and position of spacecraft. T96 model is used to calculate magnetic shell parameter, and the difference between L values calculated from Dipolar model, IGRF and T96 were compared. The difference between L values calculated from Dipolar model and IGRF, begin to increase when magnetic latitude is larger than 30? Also,the difference between L values calculated from IGRF and T96, begin to increase when magnetic latitude is larger than 50? The L values are therefore dependent on the IMF (interplanetary magnetic field) and have also the dependence of local time. This work is meaningful to radiation belt dynamic modeling and understanding of magnetic position of satellite.
ONE CASE STUDY ABOUT THE IONOSPHERIC RESPONSE TO ONE GREAT SOLAR FLARE IN THE SUN-LIT HEMISPHERE
ZHANG Donghe, SUN Zhen, LIU Siqing, GONG Jiancun, XIAO Zuo
2004, 24(2): 96-104.
Abstract(2108) PDF 815KB(992)
Abstract:
The characteristics of the ionospheric response to one great solar flare was studied using the total electron content derived from GPS observational stations in the whole sun-lit hemisphere under International GPS Service for Geodynamics (IGS). It was found that the largest enhancement of the Sudden Increase of Total Electron Content (SITEC) during this flare is about 2.6 TECU (1 TECU= 1016/m2). The effects of solar flare radiation on the ionosphere can be recognized even in the region at 0600 LT or 1800 LT. Due to the ionospheric scintillation, the TEC enhancement couldn’t be derived from temporal TEC variation curves in the high latitudes. On the other hand, the synoptic picture of the sun-lit ionospheric response to the flare was obtained and the results showed the relationship of TEC enhancements with solar zenith angles. The larger the solar zenith angle, the smaller the TEC enhancement. It was worth mentioning that even the minor fast changes in TEC during this flare can be revealed from the changing rate of the temporal TEC variation curves in mid- and low latitudes. These minor and global synchronous disturbances of TEC were compared with the solar X-ray flux of this flare observed by satellites, and a close correlation between those minor ionospheric disturbances and the hard X-ray flux fluctuations is found.
RELATIONSHIP BETWEEN THE METEOR SHOWERS AND THE OCCURRENCE OF SPORADIC E OVER WUHAN
NIU Xiaojuan, XIONG Jiangang, WAN Weixing, NING Baiqi, LIU Libo, YUAN Hong
2004, 24(2): 105-111.
Abstract(2666) PDF 651KB(1249)
Abstract:
This paper analyzes the relationship between the occurrence of sporadic-E and the meteor numbers during the Perseids, Leonids and Geminids meteor showers in 2002 and Quadrantids meteor shower in 2003 over Wuhan (30°32′N, 114°22′E). The data used here are derived from an all-sky meteor radar and a digital ionosonde at Wuhan. The results show that the meteor number increased during the outburst of meteor showers and that the occurrence frequency of strong Sporadic-E also increases after the outburst of meteor showers. There are two peaks for the mean Cross-correlation function between the meteor number and the occurrence rate of Sporadic-E, one appears around the second day after the outburst of meteor shower and the other appears around the sixth day. It is suggested that the first peak could correspond to the Sporadic-E produced divectely by many meteors ionization during the outburst of meteor shower, the second peak could correspond to the Sporadic-E produced by the subsequent action of wind shear on residual meteor ion concentrations.
LET DISTRIBUTION AND ABSORBED DOSE IN SZ-3 RECOVERER
JING Guiru, REN Guoxiao
2004, 24(2): 112-118.
Abstract(2086) PDF 586KB(1174)
Abstract:
In order to measure the absorbed dose and the dose equivalent induced by heavy ions which enter the space capsule inside, a solid state nuclear track detector is installed in the inner wall of SZ-3 recoverer. This detector is composed by the sandwich of CR-39 sheets and aliminium sheets. The flight time of the detector on board of SZ-3 is about 162 h. After the chemical etching for recoverd CR-39 sheets, we scaned and measured the ion track spots on the CR-39 sheets. Refering to the calibration value for different ions provided by heavy ion accelerator experiment and subtracting the background provided by the contrast samples on the ground, the linear energy transfer (LET) distribution in recoverer are obtained. When the linear energy transfer (LET) is larger than the threshold of the detector, the integral intensity is (4.667±0.071)×10-5cm-2·s-1·sr-1. For LET > 12.6keV/μm (H2O), the total absorbed dose and the total dose equivalent are (23.50±0.46)μGy and (355.6±9.7)μSv, respectively. The relationship between the total dose equivalent and the thickness of shield are obtained.
SOLAR RADIATION MEASUREMENT ON SHENZHOU-3 SPACECRAFT
YU Bingxi, FANG Wei, YAO Haishun, AN Yu, GONG Chenghu, LI Zhe, JIN Xifeng, LU Daren
2004, 24(2): 119-123.
Abstract(2237) PDF 459KB(1380)
Abstract:
TSI (Total Solar Irradiance) has been measured by solar constant monitor, which is composed of three SIAR (Solar Irradiance Absolute Radiometer), on board of Shenzhou-3 spacecraft from March to September in 2002. The structure of the cavities has been improved, the substitution winding being embedded in the wall of each SIAR’s cavities, so the absolute precision is heightened. Solar irradiance was measured when the sun scans over the field of view of each absolute radiometer respectively. The data is coincident with the data simultaneously measured by EOS/ACRIM in 0.2%.
A NEW KINEMATIC METHOD FOR FLYING-AROUND SATELLITE FORMATION DESIGN
LU Hongwei, XI Xiaoning, YU Qifeng
2004, 24(2): 124-131.
Abstract(2111) PDF 593KB(1235)
Abstract:
This paper presents a new kinematic design method for satellite formation. First, the kinematic of the relative motion of zero inclination satellite formation is analyzed and orbit design is investigated. And orbit transformation method is proposed for arbitrary inclination satellite formation orbit design. Finally, the simulation results show that the method is effective and feasible.
LAYOUT OPTIMIZATION OF LARGE FLEXIBLE DEPLOYED ANTENNA
LUO Ying, DUAN Baoyan
2004, 24(2): 132-137.
Abstract(1934) PDF 505KB(1035)
Abstract:
Based on a new flexible cable net for a deployable antenna, the optimum design of cable system is discussed in the paper. An optimum design model is presented, searching for minimum weight design while the constraints such as reflector precision is concerned. The design parameters are selected as the number of upper cable, lower cable and adjustable cable. Through a numerical example, the model above is tested and verified to be correct and effective.
RESEARCH ON DYNAMIC ORBIT DETERMINATION FOR GEOSTATIONARY SATELLITE USING TWO-WAY PSEUDORANGE
JIA Xiaolin, JIAO Wenhai, WANG Gang, WU Xianbing, CHEN Jinping
2004, 24(2): 138-144.
Abstract(1849) PDF 550KB(965)
Abstract:
In this paper, a study on the dynamic orbit determination for geostationary statellite using two-way pseudorange observations are presented. The satellite observation equation and the method for correcting the observations in term of the two-way pseudorange are given. The simulating calculations are performed by using the observation data set of the four monitor stations in China. The results show that the precision of the orbit improvement and extrapolation using seven days two-way pseudorange observation data set are same as those of five days are, but much better than three days’ data set under the condition of random error in 3 m. Using seven days observation, the precision of the orbit improvement is about 5 m and the radial precision of the orbit predication is about 20 m.
DISCRETE VARIABLE STRUCTURE CONTROL OF FLEXIBLE CANTILEVER BEAM
CAI Guoping, HONG Jiazhen
2004, 24(2): 145-151.
Abstract(2041) PDF 596KB(1371)
Abstract:
Active control method for the vibration reduction of flexible cantilever beam is investigated in this paper. The independent modal space control method is used as control strategy, in which modal control law is designed using discrete-time variable-structure control method. Extraction of modal variables from actual measurements and transformation of actual control forces from modal control forces are discussed. Determination methods of discrete-time switching surface and variable-structure modal control law are presented. Effectiveness of the proposed control method is verified through a numerical simulation in the end of this paper.
STUDY ON DYNAMICS SIMULATION OF THE STRUCTURAL LOCK OF SPATIAL DOCKING MECHANISM BASED ON THE MULTI-BODY SYSTEMATIC ANALYSIS
WU Yizhong, CHEN Liping, ZHANG Yunqing
2004, 24(2): 152-160.
Abstract(2102) PDF 706KB(1240)
Abstract:
The paper analyzed the characteristics of structural lock performing mechanism of spatial docking system and the difficulties of solving the model of the mechanism through dynamic analysis software on hand. And them the modeling method of multi-body dynamics is adopted and dynamics equation of the mechanism is established. The solving process considering the special features of the model is also narrated. Finally, the result of dynamics characteristics curves which are obtained from the model proved that the ball bearing lead screw mechanism aided by spring mechanism is feasible as the structural lock performing mechanism.