2011 Vol. 31, No. 3

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Understanding substorms in the magnetotail: early development and recent progress
A. Nishida
2011, 31(3): 269-293. doi: 10.11728/cjss2011.03.269
Abstract(2166) PDF 1622KB(1230)
Abstract:
This is a concise review of physics of the substorm in the magnetotail. It consists of two parts. The first part summarizes historical developments in the early days of the space age (1960--1975) when the basic concepts such as magnetotail and reconnection were established and the leading model of the substorm was introduced. The second part is an overview of the research conducted in recent years (1995--2010) when very significant advances have been achieved in understanding the substorm physics by virtue of several major satellites missions that addressed the magnetotail physics intensively.
Analysis of the Interplanetary Sources for the Main Phase of the Geomagnetic Storm During October 18---19, 1998
Zhang Yang, Le Guiming, Liu Lianguang
2011, 31(3): 294-298. doi: 10.11728/cjss2011.03.294
Abstract(3078) PDF 457KB(1154)
Abstract:
Using solar wind data with time resolution 64 s and SYM-H data with time resolution 1 min and considering the delayed geoeffectiveness of solar wind observed at L1, we reinvestigate the Interplanetary (IP) sources for the main phase of the geomagnetic storm occurred during October 18--19, 1998. The results indicate that only the sheath made contribution to the main phase of the geomagnetic storm. The Interplanetary Coronal Mass Ejection (ICME) started at 03:51 UT, October 19, 1998 and ended at 14:17 UT, October 19, 1998 having the southward interplanetary magnetic field with averaged value 16.8 nT made no contribution to the main phase of the geomagnetic storm. The proton density and the dynamic pressure of the ICME was only 5.2 cm -3 and 1.43 nPa respectively. The results indicate that the product of solar wind density and the south component of IMF determine the development of the main phase of a geomagnetic storm.
Attenuation of Alfven Waves in Weakly Ionized Near Earth Atmosphere
Liu Yuantao, Zhao Hua, Li Lei, Wang Jindong, Zhou Bin, Feng Yongyong
2011, 31(3): 299-303. doi: 10.11728/cjss2011.03.299
Abstract(2359) PDF 489KB(1164)
Abstract:
Alfven waves, produced on the ground by artificial or by soundstorm, propagating to the near-earth space along the geomagnetic field lines, would decay greatly with distance. A dipole geomagnetic field model in near earth space, plasma density and conductivity models derived from observational data are used in this study to investigate the attenuation of Alfven waves below 1000 km altitude by numerical simulation methods. The frequency that would be detected by magnetometer carried by satellite was also found. The result showed that: Alfven waves will decay sharply in the height of less than 50 km for the much weak electrical conductivity in this region; it is 0.4 Hz Alfven waves, when transmitted to 1000 km, that becomes about one-thousandth of the original, so Alfven waves below 0.4 Hz can be detected by LEO satellites.
Forecasting of ionospheric f0F2 in China using neural network
Chen Chun, Wu Zhensen, Sun Shuji, Ding Zonghua, Xu Zhengwen, Ban Panpan
2011, 31(3): 304-310. doi: 10.11728/cjss2011.03.304
Abstract(2616) PDF 651KB(1217)
Abstract:
By using artificial Neural Network (NN) and considering the effects of the solar and geomagnetic activities on the ionosphere in this paper we brought out a method to forecast the ionospheric critical frequency, f0F2, in China up to 5 hours ahead. The inputs of the NN are time, day of the year, geographical latitude, solar zenith angle, the twelve recent past observations of f0F2 (F-23, F-22, F-21, F-20, F-19, F-18, F-5, F-4, F-3, F-2, F-1, F0) and the 30-day mean moving values of f0F2 (A-24, A-23, A-22, A-4, A-3, A-2, A-1, A0) from the target location. The outputs of the NN are F+1, F+2, F+3, F+4, F+5, representing the values of f0F2 up to 5 h ahead. Data from Wulumqi, Changchun, Chongqing and Guangzhou stations spanning the period 1958---1968 are used for training the NN. Historical data at nine different stations in China are used to checkout the network respectively (Not including the training set). The performance of the NN is measured by calculating the Root-Mean-Square error (RMS) difference between the NN outputs and measured station data. The results indicate that the prediction of NN has good agreement with measured data. Taken into account those temporal and spatial inputs mentioned above, the NN can be applied successfully in the short-term forecasting of the ionospheric f0F2 in China.
Research on correlation between gravity waves energy and jet
Li Wei, Yi Fan
2011, 31(3): 311-317. doi: 10.11728/cjss2011.03.311
Abstract(2237) PDF 576KB(918)
Abstract:
By analyzing the routine Radiosonde data obtained at Wuhan (30.5ºN, 114ºE) from 2000 to 2004, some characteristics of inertial gravity wave in Troposphere and Lower Stratosphere (TLS) were studied, and a strong correlation between the variation of gravity wave energy and jet intensity was found. Similar result of Wuhan was obtained by analyzing the routine Radiosonde data obtained at Haikou (20ºN, 114ºE) and Beijing (40ºN, 116ºE), and stronger correlation was found in higher latitude area. An intensive Radiosonde observation at Wuhan, which lasted 5 days in Jan 2006, was conducted to examine the variation with altitude of gravity wave kinetic energy and potential energy, and it was demonstrated that the excitation of gravity wave in TLS is attributed to jet (zonal wind shear), which suggests that it's a main excitation source of gravity wave in lower atmosphere.
Abnormal variation of thermosphere atmospheric density during the period of big earthquake
Zeng Hong, Zhu Guangwu, Qin Guotai, Chen Huajiao, Li Yongping
2011, 31(3): 318-322. doi: 10.11728/cjss2011.03.318
Abstract(2790) PDF 660KB(1031)
Abstract:
Earthquake is the natural disaster that human beings are most concerned about, while the influence of earthquake on the density of the thermosphere is not clear. Recently, it was occurred a class of 8.0 big earthquake on May 12, 2008 in Wenchuan City, Sichuan province in China. Later, a series of big earthquake events with the class 7.0~7.6 happened in the east of Honshu in Japan on June 14, Okhotsk on July 5 and the east seacoast of Honshu on July 19. During the course of earthquake events, an atmospheric density detector on board of the solar synchronous satellite at the orbital altitude of 630 km worked all the time and got a large quantity of in-situ measurement data. According to the data, it was discovered that the abnormal atmospheric density decrease over the center region of the earthquake source on the earthquake day. During the period about 1~3 days before the strong earthquake, the decrease of upper atmospheric density has been existed and reached the valley on the earthquake day with the decreasing ratio ranging from 0.40 to 0.65. Furthermore, the range of the decrease located at the latitude of ± 3 º~±9 º from the earthquake center before the earthquake, but it expanded to about ± 8 º ~±20 º from the earthquake center on the earthquake day.
Detection of Martian ionosphere
Zou Hong, Chen Hongfei, Shi Weihong, Zou Jiqing, Zhong Weiying, Yu Xiangqian
2011, 31(3): 323-329. doi: 10.11728/cjss2011.03.323
Abstract(3088) PDF 680KB(1140)
Abstract:
The exploration of Mars began in the early 1960s and has become the main subject of the space exploration recently. The Chinese deep space project (mainly focused on Mars) is developing. ``Land on Mars and live on Mars'' is the ultimate object for the Mars exploration and the Martian ionosphere is one of the environments to be understood necessarily. In this paper the basic methods of the Martian ionospheric detection and the typical results are introduced. The direct detection has the advantages of high precision, good spatial resolution, but it can not provide a long-term stable observation due to the short measuring time. The main indirect detection results of the Martian ionosphere come from the radio occultation method and the topside sounder. The radio occultation measurement provides a long-term stable detection of the whole profile of Martian ionosphere, but its horizontal resolution is not good and the Solar Zenith Angle (SZA) range of the measurement is limited by the orbits of Earth and Mars. The topside sounder can also provide a long-term stable measurement with high temporal and spatial resolutions, which gives new support for Martian ionospheric exploration. The combination of these detection methods will greatly improve the research of Martian ionosphere.
Real time monitoring the orbit insertion of Chang'E-1 lunar mission
Ping Jinsong, Wang Mingyuan, Shi Xian, Jian Nianchuan
2011, 31(3): 330-337. doi: 10.11728/cjss2011.03.330
Abstract(2907) PDF 854KB(1079)
Abstract:
China's first lunar satellite Chang'E-1 (CE-1) was launched on Oct. 24, 2007. During its flight to the Moon, a series of maneuvers were performed to keep the satellite in the correct trajectory. Among these maneuvers, the one performed for Lunar Orbit Insertion (LOI) was the most important part since it directly decided whether the satellite could enter the mission orbit or not. Therefore, real time monitoring and estimation of the satellite's state during this stage became crucial. A system was developed for LOI monitoring using as few data as possible. This system included real time data transmission as well as real time data analysis which could provide the difference between the predicted and observed measurements in the first place, and then, most importantly, it also gives the ensuing orbit insertion conditions, i.e., predicts probable future orbit parameters after the maneuver. The presented method was successfully applied for the LOI process in the mission phase.
Photometric techniques in mutual events of Galilean satellites
Chen Bin, Peng Qingyu
2011, 31(3): 338-343. doi: 10.11728/cjss2011.03.338
Abstract(2287) PDF 595KB(850)
Abstract:
The photometry of mutual occultations and eclipses of Galilean satellites of Jupiter can be used to deliver very accurate astrometric information, which can be further used for improvement of the dynamical models and their ephemerides of the concerned satellites. The photometry of the CCD images of mutual occultations and eclipses of Jupiter's satellites which were observed at Yunnan Observatory in 2003 was done and light curves in different situations were obtained. From the light curves, the midlight time and the decline magnitude can be obtained. It is found that the light curves will be stable when the halo around the Jupiter is removed and the photometric apertures are assigned between 1.5 and 2.0 times of FWHM of satellite's image.
Astrometric experiment for the 1m telescope at Weihai observatory
Lin Zhong, Peng Qingyu, Zhang Qingfeng
2011, 31(3): 344-349. doi: 10.11728/cjss2011.03.344
Abstract(3484) PDF 577KB(1440)
Abstract:
The open cluster M39 was observed by the new 1-m telescope at Weihai Observatory, Shandong University in the night of Oct. 7, 2009. While observing, a Johnson I-type filter was used and the CCD was imaged in two orthogonal orientations, and thus 30 frames of images were delivered. After the CCD images were measured by 2-D Gaussian fit so as to obtain the star pixel positions, a number of constant plate models were attempted to solve the difference between observed positions and computed ones for each star. Our reduction of the observations showed that proper motions of the latest USNO UCAC3 star catalogue were explicitly not accurate. By contrast, those of the Platais's catalogue were found much better. This observations partly confirmed the errors in the proper motions of UCAC3 recently discovered by Roeser et al. Experiments have also shown that the best precision for a suitable bright star was about 4~5 milli-arcsec. It was believed that this new telescope could be used for high precision astrometry.
Simulation study on single event upset induced by near space atmospheric neutron in electronic devices
Zhang Zhenli, Zhang Zhenlong, Han Jianwei, An Guangpeng, Cai Minghui, Feng Guoqiang, Ma Yingqi
2011, 31(3): 350-354. doi: 10.11728/cjss2011.03.350
Abstract(2905) PDF 509KB(1015)
Abstract:
Single Event Upset (SEU) induced by atmospheric neutron is harmful for near space craft, and is studied by numeric simulation in present paper. Static Random-Access Memory (SRAM) device which has regularly arrayed cells is selected as the simulation object. Using Rectangular Parallelepiped (RPP) Model as the basic model and extracting key parameters from SEU experiment data of heavy ions, sensitive volume model of SEU due to nuclear reactions between incident neutron and device materials is established. Simulation and research show that the secondary heavy ions resulting from the high energy neutrons can transfer approximate 4 microns. Consequently, to simulate the SEU events thoroughly, an extra volume beyond 4 microns from the sensitive volume is taken into account. Modeling and simulation are performed for HM62256 and HM628128 SRAM devices respectively with the help of GEANT 4 software package. The secondary particles in and near the sensitive volume contributing to SEU are considered. Differential spectrums of the deposited energy in the sensitive volume by the secondary particles are calculated. Eventually SEU events due to the secondary particles which deposited different energy in the sensitive volume are summed up. The results of the simulation agree well with those of ground experiments performed with 14 MeV neutrons and high energy protons.
Effect of G-Jitter on multiphase fluid systems
Liang Ruquan, Liang Shuang, Ji Junhong, M. Nasr-Esfahany, N. Ichikawa, M. Kawaji
2011, 31(3): 355-360. doi: 10.11728/cjss2011.03.355
Abstract(2872) PDF 590KB(951)
Abstract:
The effects of G-Jitter on the surface oscillation and internal flow structure of a liquid bridge have been investigated in order to understand the effect of G-Jitter on the multiphase fluid systems. The theoretical analysis shows that the resonance frequency of the liquid bridge changes depending on the size and physical property of the liquid bridge. The experimental study indicates that there may be a triple coupling link between the vibration-induced surface oscillations and flow/temperature oscillations inside the liquid bridge. The numerical results reveal the flow structure inside the liquid bridge when G-Jitter is applied on the liquid bridge. Moreover, our results from the theoretical analysis as well as experimental study are compared with those from the numerical simulation, and the theoretical and experimental results match the numerical ones well.
Application of primer-vector theory in close intercept optimization
Wang Guoliang, Zheng Jianhua
2011, 31(3): 361-365. doi: 10.11728/cjss2011.03.361
Abstract(3404) PDF 435KB(1375)
Abstract:
In this paper, the optimum of the fuel consumption in close impulse interception within a fixed period of time by principal vector theory was mainly studied. Then a mathematical model of space interception of short distance based on the theory of orbital dynamics was set up. According to the principal vector theory, a theoretic criterion was put forward to determine whether the optimum of impulse interception has been attained, and an optimization technique for the interception was raised too. The effectiveness of the optimization was verified by lots of simulation examples. In the latter part of the paper, the fuel consumptions of the space interceptions at different time were simulated, compared and analyzed, and at last a technique to achieve optimal fuel consumption of the interception was brought forward.
Effect of navigation constellation incompleteness on dilution of precision of autonomous orbit determination using inter-satellite link
Liu Wenxiang, Yong Shaofei, Wang Feixue
2011, 31(3): 366-371. doi: 10.11728/cjss2011.03.366
Abstract(2884) PDF 533KB(1113)
Abstract:
Navigation satellites Autonomous Orbit Determination (AOD) using inter-satellite link is the key technology of the constellation autonomous navigation. In conditions such as uncompleted constellation establishment on the early construction, malfunction and destruction of satellites, several satellites of the constellation may be unavailable, therefore the research of constellation incompleteness' effect on satellites AOD is valuable. Based on presenting the AOD method of weighted least squares solution one by one, this paper introduced the AOD Dilution of Precision (DOP) values as merit index and analyzed the effect of the Galileo constellation by simulations. The results show that the visual satellites are quite redundant in satellite's AOD process of the Galileo constellation, and there is no prominent effect of constellation incompleteness on the AOD dilution of precision. Only when the number of satellites is reduced by 2/3, there will be several satellites whose DOP values of AOD exceed the threshold. The method is also adoptable in analysis of other navigation constellation.
Analysis of geomagnetic navigation accuracy under magnetic storms
Guo Caifa, Zhang Lijun, Cai Hong
2011, 31(3): 372-377. doi: 10.11728/cjss2011.03.372
Abstract(3676) PDF 579KB(1498)
Abstract:
Geomagnetic navigation is a new branch of the passive autonomous navigation technique. The theory of geomagnetic navigation was analyzed. The process of typical magnetic storm is described. The feasibility of geomagnetic navigation during magnetic storms is analyzed in this paper. With employment of experimental data, the measurement equations are obtained by using surface Spline method. Extended Kalman Filter (EKF) is applied to navigation calculation, and the navigation accuracy is discussed during different phases of magnetic storm. The simulations are calculated with theoretical model data and real magnetic storm data. Results show that the feasibility of magnetic navigation is verified during the initial and later recovery phases of all the storms. And the conclusion is also valid in all the phases of a storm which is less than or equal to moderate intensity. Positioning error is lower than 200 m, which meets the guidance requirement in the mid-course of flight vehicle.
Application of satellite remote sensing technology in monitoring underground nuclear test
Yan Weidong, Zhao Yigong, Ni Weiping, Sun Bin, Wang Peizhong
2011, 31(3): 378-383. doi: 10.11728/cjss2011.03.378
Abstract(3164) PDF 910KB(1166)
Abstract:
Satellite remote sensing technology plays an irreplaceable particular function in discovering, monitoring, identifying, locating, and analyzing the underground nuclear test, and makes it possible to deter the nuclear explosive test beforehand. Surveillance and verification of the Comprehensive Test Ban Treaty (CTBT) by satellite is a highly complex all-around decision-making process. Several effective remote sensing techniques were presented with examples in this paper, such as serial image analysis, image fusion, change detection, K-L transform, D-InSAR, DEM, GIS database. The limitation of the satellite remote sensing technology is also indicated, that is, it is unable to determine the underground nuclear explosion in physics term, and therefore false and missed alarms can not be avoided effectively.
Construction and measurement method research of an inflatable antenna
Zhao Xin, Guan Fuling, Wang Hongjian, Xu Yan
2011, 31(3): 384-389. doi: 10.11728/cjss2011.03.384
Abstract(3921) PDF 609KB(1142)
Abstract:
An inflatable antenna is analyzed and designed, initial shape surface and cutting-pattern of inflatable reflector are obtained. High precision cutting module and seaming module are manufactured, which are used to develop the 3.2\,m diameter antenna prototype. By a series of manufactured adjustment devices, inflatable antenna is installed to rigid support structure. Two kinds of adjust methods for cable tensional force are compared and analyzed, and finally spring adjust device is adopted. Non-contact photogrammetry measurement system is used to measure the inflatable reflector with repeated adjustment. A measurement method featured by departing target with 5 parts for the large diameter inflatable antenna is found after repeated contrast. Finally a high shape precision of antenna reflector is achieved. The measurement results are analyzed to identify the deviation and an improved method is proposed. These efforts can be referred for design and experiment on high-precision inflatable antenna.
Design and thermal analysis of space dual-axis solar array drive assembly
Li Jianhui, Li Ruixiang, Qian Zhiyuan
2011, 31(3): 390-394. doi: 10.11728/cjss2011.03.390
Abstract(3885) PDF 621KB(1425)
Abstract:
his paper introduced a lightweight Dual-axis solar array drive assembly (SADA), aiming at two key technologies of lightweight and long life. The Dual-axis SADA consists of A-axis which provides 360º of rotation and power transfer through the use of a slip ring device and B-axis which provides ±90º of travel and incorporates a simple flex loop for power transfer. The accelerated life test of key moving parts of SADA including the slip ring and the harmonic reducer were preformed and passed. The designed principle prototype of SADA has some merits, such as compact structure, good stiffness and light weight. The thermal analysis of the Dual-axis SADA had been preformed. The measures of thermal control are presented by comparing temperature distribution under different schemes.
Topology optimization design for main board of lightweight space camera
Jia Xuezhi, Jin Guang, Jia Jiqiang, An Yuan, Xu Zhen
2011, 31(3): 395-400. doi: 10.11728/cjss2011.03.395
Abstract(2741) PDF 633KB(1135)
Abstract:
In order to obtain a lightweight and high-stiffness main board structure for lightweight space camera, a topologic optimization design method was presented. FE (Finite Element) based topology optimization which is created with the variable-density method is executed to find the optimum material distribution of initial design main board of space camera by maximizing the stiffness. Compared with that before the optimization, the main board structure reduces weight from 36.8 kg to 15.4 kg, loses 58.2 percent weight with the first-order natural frequency above 400 Hz. In order to check whether the main board's distributing of stiffness is rational, the Finite Element Method (FEM) is used to analyze the model of the main board. Finally, the 0.5 g vibration test shows that the first natural frequency of main board is 479.2 Hz, which is very close to the result of the FEM, the error is 1.86 %. The numerical results indicate that after adopting the topologic optimization design method, not only the design course is shortened, but also the main board structure weight is effectively reduced and the capability of the main board structure is enhanced also, which shows that optimized board structures can meet the system design requirements well.
Study on fabrication technology of reaction bonded silicon carbide mirror blank for space
Zhang Ge, Zhao Rucheng, Zhao Wenxing
2011, 31(3): 401-405. doi: 10.11728/cjss2011.03.401
Abstract(3219) PDF 624KB(1424)
Abstract:
Silicon Carbide (SiC) is a new type of candidate material for large-scale lightweight space born mirror. Its low thermal distortion, high stiffness, high optical quality, and its dimensional stability are better than other traditional optical substrate materials such as ULE, Zerodure, Beryllium (Be) and so on. In this paper, the lightweight silicon carbide space mirror blank was fabricated by reaction sintering. Lots of large scale SiC green bodies were prepared by a gel-casting method with the lost mould technology. And the size of the largest SiC green body with sandwich structure is 1080 mm × 820 mm now. After drying, burning out the organic elements and reaction sintering, the reaction bonded SiC (RB-SiC) mirror blanks were fabricated. The test results of ground mirrors show that the structure of RB-SiC is fully solid, and the mechanical and thermal properties of RB-SiC are excellent in elastic modulus of 330 GPa, bending strength of 340 MPa, fracture toughness of 4.0 MPa•m1/2 and Coefficient of Thermal Expansion (CTE) of $2.6\times 10-6 K-1. The surface roughness (RMS) of the polished mirror is better than 3 nm, which means SiC is a fine candidate material for the spaceborne mirror.
Quasi-cyclic expansion and encoding algorithms for protograph LDPC codes
Li Zhongliang, Xia Guojiang
2011, 31(3): 406-411. doi: 10.11728/cjss2011.03.406
Abstract(2452) PDF 482KB(1306)
Abstract:
Recently, a new class of Low-Density Parity-Check (LDPC) codes constructed from a template was introduced. This kind of codes were called protograph codes. The protograph serves as a blueprint for constructing LDPC codes of arbitrary size whose performance can be predicted by analyzing the protograph. Protograph LDPC codes perform very well and suit for high-speed encoding and decoding. However, there are few researches on expansion and encoding algorithms for them. In this paper, using isomorphism between matrix ring and polynomial ring, we propose efficient quasi-cyclic expansion and encoding algorithms for protograph LDPC codes. Simulation results show that the protograph LDPC codes which were constructed by the algorithm proposed in this paper, outperform the best known unstructured irregular LDPC codes with the same maximum node degrees.

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