空间科学学报

2004 Vol. 24, No. 1

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IMPROVEMENT ON THE CME NUMERICAL SIMULATION OF CME BETWEEN TWO STREAMERS

YE Zhanyin, WEI Fengsi, WANG Chi, FENG Xueshang, XIANG Zhangqing

2004, 24(1): 1-7. doi: 10.11728/cjss2004.01.20040101

Abstract(2452) PDF 667KB(1013)

Abstract:

The solar magnetic field is improved by properly combining a dipole and a hexapole to make the polarity at two solar poles opposite. The self-consistent steady state with two streamers, satisfying observation qualitatively, is obtained by long time interaction between the initial combined potential magnetic field and solar wind flow. Then the CME triggering model with concentrically circular closed magnetic field structure is taken to trigger CME between two streamers for research about CME propagating features near corona. The numerical result shows that the CME event is confined by the two streamers to propagate between them and the closed CME magnetic field structure is similar to that in the section of magnetic cloud, which can explain some features of magnetic cloud observed at 1 AU. Moreover, it is found that there exist some areas, where pressure and Lorentz force dominate flow, which could be helpful for analysis of CME event data observed at 1 AU.

THE VELOCITY VARIATION OF INTERNAL SHOCK IN GRB

CHEN Li, WU Mei, QU Jinlu, YANG Zhiliang

2004, 24(1): 8-14. doi: 10.11728/cjss2004.01.20040102

Abstract(2257) PDF 613KB(888)

Abstract:
With the BATSE TTS model data, the work analyzed the sub-pulse width and the time lag between high and low energy band of GRB960113, which is in simple shape and good SNR. The result shows that the lags and widths increase and broaden monotonously with time. In the general views, the internal shock is produced by collision of shells with random Lorentz factors. Here, a special picture is considered, i.e., an extremely relativistic shell from the center catches up and collides with the outer slow shells successively, it produces the Gamma-ray emission, then the fast shell slow down. After collision, the Lorentz factor of the slow shell is basically in direct proportion to that of the quick one. Therefore, the variation of Gamma ray emission can reflect the change of the velocity of the fast shell. From the relation $\frac{\gamma_j}{\gamma_i}=\frac{\Delta t_i}{\Delta t_j}$（where γ_i is the Lorentz factor of pulse i, △t_i is the time lag of pulse i observed in the rest frame）, the decrease of γ necessarily induces the increase of △t. The variances in GRB960113 is consistent with such case. If the Gamma rays are produced with an internal shock, the result shows that there is velocity variation of internal shock. The work also calculates the time lag of every sub-pulse of 88 GRBs in TTS data. Majority is high-energy photons leading; the distribution has a peak around -25 ms. This paper has advanced a new idea in using the BATSE TTS data to produce light curves with 8 ms time resolution. This is as opposed to the usual 64 ms resolution used by all previous studies. This is an improvement that will substantially help with measuring the lags for the highest luminosity bursts which have lags shorter than 64 ms.

THE DETERMINATION OF TRAVLING DIRECTION OF SEVERAL CMEs CAUSING SEVERE GEOMAGNETIC STORM

LE Guiming, YE Zonghai

2004, 24(1): 15-21. doi: 10.11728/cjss2004.01.20040103

Abstract(2392) PDF 713KB(1172)

Abstract:
Coronal Mass Ejections （CMEs） are important factors for the space weather. The geomagnetic storms with sudden commencement are caused by CMEs. CMEs with the south direction of B_z ＞ 10 nT and high traveling speed can often cause intensive magnetic storm. But many problems keep unsolved on the relationship between a CME and the intensity of the relative geomagnetic storm. In this paper, the traveling directions of several coronal mass ejections causing severe geomagnetic storm are investigated by using the galactic cosmic ray data observed at McMurdo and Thule neutron monitor. If a CME’s traveling direction straightly towards to magnetopause, then the variation in galactic cosmic ray intensity observed at the two stations should be almost the same. Several selected CME events are analyzed. The results show that the direction of the CME related to the geomagnetic storm on Dec.19, 1980 was almost dead against magnetopause, the situation was the same for the CMEs related to the geomagnetic storms on Jul.13, 1982, Nov.6, 2001 and Mar.31, 2001. The traveling direction of the CME related to the geomagnetic storm on Jul.15, 2000 is slightly directed to south of the earth. By comparing the intensity of the geomagnetic storm on March 31, 2001 and July 15, 2000 and comparing the disturbed solar wind driven by corresponding CME, it is thought that the traveling direction of a CME is a factor having impact on the intensity of the geomagnetic storm caused by the CME. For a CME, the more deflection of its traveling direction towards the magnetopause, the weaker the geomagnetic storm caused by it.

THE GEOMAGNETIC RESPONSE OF JULY 2000 EVENT

WANG Tanwen

2004, 24(1): 22-27. doi: 10.11728/cjss2004.01.20040104

Abstract(2469) PDF 462KB(812)

Abstract:
The geomagnetic field responds to the July 2000 space event much. A great storm （magnetic index K = 9） occurred from July 15 to July 18. There is a sudden commencement with amplitudes about 200-300 nT in China region. The maximum amplitudes during the main phase in China region are about 500-600 nT. That is infrequent for a few years. The B_z component of IMF is turning to southward when the main phase of the storm begins, and after the southward component （B_z＜ 0) decrease to the minimum, two hours later the storm recovery phase begins. The paper shows that there are some relationship between the solar wind and the storm.

MORLET TRANSFORM OF SUNSPOT NUMBER AND Ap INDEX

MIAO Juan, TIAN Jianhua, LIN Zhenshan

2004, 24(1): 28-34. doi: 10.11728/cjss2004.01.20040105

Abstract(2614) PDF 627KB(1277)

Abstract:
In this paper, Morlet wavelet transformation is applied to analyze the character of sunspot number and Ap index from 1932 to 2000 including solar cycle 17 to the rising phase of solar cycle 23. By the several examples selected during solar maximum and minimum respectively, three conclusion are drawn: （1） Sunspot number and Ap index both have obvious 11-year period and 32-year period, and Ap index also has 6-month period that exist in all phase, 27-day period and 13.9-day period. （2） Compared with the 11-year period of sunspot number, the maximum value of Ap index appears one or two years latter than that of sunspot number. （3） The 27-day period of Ap index is different during solar maximum and solar minimum. During solar minimum, Ap index has stable 27-day period. But during solar maximum, the character of 27-day period disappears or changes. And wavelet transformation could show detailed time when 27-day period vanishes and recurs.

“SZ-3”ATMOSPHERIC COMPOSITIONS DETECTOR MEASUREMENT RESULT——ABNORMAL CHANGE OF THE UPPER ATMOSPHERE COMPOSITION DURING GEOMAGNETIC ACTIVITY DISTURBANCE ON APRIL 2002

QIN Guotai, QIU Shiyan, HE Aiqing, ZHU Yiqiang, SUN Lilin, LIN Xianwen, LI Hong, XU Xuepei, YE Haihua

2004, 24(1): 35-42. doi: 10.11728/cjss2004.01.20040106

Abstract(138) PDF 655KB(3)

Abstract:
An atmospheric composition detector born on spacecraft "SZ-3" lunched on 26 March 2002. It met two times geomagnetic activity disturbance events during April 2002. "SZ-3" atmospheric composition detector measurements show the change and abnormal phenomenon of atmospheric composition on 330-350 km. Measurement results show that not only the responses of the O and N₂ density in creases during geomagnetic activity disturbance events, but also the phenomenon of the abnormal N₂ density increases and the abnormal O density decreases, during the peak of geomagnetic activity disturbance events, and it moved from 42°N to lower latitude （near 27°N） during 4-5 hours. The reason causing above mentioned phenomena might be relative to the energetic particle input into the pole and high latitude region which heats the upper atmosphere in a large scale and produce a large scale air upstream which brings the air from lower altitude up to higher altitude and results in the above mentioned abnormal changes. The latitude circulation moves the change from high latitude to lower latitude region.

OPTIMIZATION OF REGIONAL COVERAGE SATELLITE CONSTELLAION BY IMPROVED NSGA-Ⅱ ALGORITHM

YAN Zhiwei, TIAN Jing, LI Hanling

2004, 24(1): 43-50. doi: 10.11728/cjss2004.01.20040107

Abstract(2402) PDF 691KB(792)

Abstract:
This paper presents a new method to design regional coverage satellite constellation, the non-dominated sorting genetic algorithm Ⅱ （NSGA-Ⅱ） based on Pareto optimal is improved and applied it to the optimization of regional coverage satellite constellation. The best solution,depending on the importance of different objects, is selected by a kind of multi attributes decision making method. Simulations on remote sensing satellite constellation are presented. The results of the simulation realized by STK and Matlab show that the algorithm can get a group of Pareto solutions. The algorithm presented in this paper can avoid selecting weights of multiple objects. On the other hand, compared with the simple genetic algorithm, our algorithm is more active. Thus the question of optimization of satellite constellation with multiple objectives can be solved.

THE PRELIMINARY THERMAL ANALYSIS AND THERMAL CONTROL DESIGN FOR POLAR ORBIT LUNAR SATELLITES WITH SOLAR PANELS IN SINGLE DEGREE OF FREEDOM

ZHANG Jiaxun, WEN Yaopu, LI Jingdong

2004, 24(1): 51-57. doi: 10.11728/cjss2004.01.20040108

Abstract(2520) PDF 720KB(1352)

Abstract:
In this paper, the thermal control designs of polar orbit lunar satellites are summarized, and take a polar orbit lunar satellite with solar panels in single degree of freedom as an example. Then, the analysis of this satellite about its outer heat flux and heat dissipation in space are conducted when it is flying towards the moon and orbiting around the moon. Based on the results of the analysis, the thermal design scheme of this lunar satellite is presented, and the problems about the thermal control of the payloads, the problems about the thermal control of the instruments and equipment on the ±y side, and the application of the thermal louver technique are described.

THE STUDY OF INTERFERENCES FROM CELESTIAL BODIES AND SOLUTIONS FOR THE INFRARED EARTH SENSOR APPLIED IN SATELLITES

LI Yuheng, LI Jianyong

2004, 24(1): 58-65. doi: 10.11728/cjss2004.01.20040109

Abstract(2214) PDF 627KB(920)

Abstract:
The infrared earth sensor is a very important part of a satellite attitude control system. Its performance and stability directly affect the security of the whole satellite. Some emergencies happened in attitude control system of China on-orbit satellites usually linked to the interference of infrared earth sensor from celestial bodies. This paper discusses what role the infrared earth sensors plays in satellite and how they are interfered. The results of interference sources analysis are presented here. Finally, some ways to precisely predict when the interference happens and how to overcome them are given. They have been successfully used in managing Chinese on-orbit satellite.

RESEARCH OF FAST ORIENTATION DETERMINATION WITH HIGH PRECISION BY TWIN-STAR SYSTEM

LU Liangqing, WU Meiping, HU Xiaoping

2004, 24(1): 66-73. doi: 10.11728/cjss2004.01.20040110

Abstract(3729) PDF 680KB(1101)

Abstract:
This paper has developed an approach of rotating the baseline to solve the key technical problem lying in the process of orientation determination by Beidou satellites’ carrier phase-identification of the original phase integer ambiguity, and the simulation result shows that the azimuth determination precision of 0.01° by a 2-meter-long baseline during 5 minutes can be achived when the non-difference phase measurement precision is better than 2 percent of a cycle.

THE DISCUSS OF APPLICATION ABOUT THE TECHNOLOGY OF OPTICAL IMAGE-STABILIZATION IN SPACE COMMUNICATION OR IN AERIAL AND AEROSPACE CAMERAL

ZHOU Qingcai, WANG Zhijian, WANG Chunyan

2004, 24(1): 74-80,73. doi: 10.11728/cjss2004.01.20040111

Abstract(2079) PDF 621KB(1054)

Abstract:
This text discusses the common theory of optical image stabilization, and gives the common formula of analyzing image stabilization. Besides that this text resolve the problem of space communication, steady aiming of space flight camera and the image stabilization. A practical example indicates that the technical of optical image-stabilization is very good when useing in space technology, which provide the important base of the design on optical image-stabilization system.