2012 Vol. 32, No. 3

Display Method:
Effect of the interplanetary electric field on the magnetopause from global MHD simulations
Huang Zhaohui, Ding Kai, Wang Chi
2012, 32(3): 305-311. doi: 10.11728/cjss2012.03.305
Abstract(1715) PDF 182KB(1260)
The north-south component Bz of the Interplanetary Magnetic Field (IMF) and solar wind dynamic pressure Pd are generally treated as the two main factors in the solar wind that determine the geometry of the magnetosphere. By using the 3D global MHD simulations, we investigate the effect of the Interplanetary Electric Field (IEF) on the size and shape of magnetopause quantitatively. Our numerical experiments confirm that the geometry of the magnetopause are mainly determined by PdBz, as expected. However, the dawn-dusk IEFs have great impact on the magnetopause erosion because of the magnetic reconnection, thus affecting the size and shape of the magnetopause. Higher solar wind speed with the same Bz will lead to bigger dawn-dusk IEFs, which means the higher reconnection rate, and then results in more magnetic flux removal from the dayside. Consequently, the dayside magnetopause moves inward and flank magnetopause moves outward.
A Prediction Method for Δf0F2min of a Single Station From Interplanetary Parameters Based on Statistical Study
Li Zheng, Wei Fengsi, Feng Xueshang, Guo Jianpeng, Xu Xiaojun
2012, 32(3): 312-320. doi: 10.11728/cjss2012.03.312
Abstract(1757) PDF 331KB(919)
Using 86 CME-interplanetary shock events, the correlation between the peak values of (a) the solar wind parameters (Bz, Ey, Pdyn) and the geomagnetic indices (SYM-H, ASY-H, Kp), (b) the coupling functions (Borovsky, Akasofu, Newell) and the geomagnetic indices, (c) the solar wind parameters/coupling functions/geomagnetic indices and the ionospheric parameter (Δf0F2min), are investigated. The statistical results show that in group (a), Bz min and SYM-Hmin have the best correlation, that in group (b), the best correlation is between the peak values of Akasofu function (Amin) and SYM-Hmin, and that in group (c), the best correlation is between Kpmax and Δf0F2min. Based on the statistical results, a method for predicting f0F2 of a single station is attempted to be set up. The input is modified Bz min and the outputs are SYM-Hmin and Δf0F2min. Then 25 CME-IPS events that caused geomagnetic storms in 1998 and 2009 are used to check the prediction method. The results show that our method can be used to predict SYM-Hmin and Δf0F2min.
Study on external weak magnetic field during magnetic quiet periods over Chinese mainland
Feng Yan, An Zhenchang, Mao Fei, Sun Han, Jiang Yong, Liu Shijun
2012, 32(3): 321-335. doi: 10.11728/cjss2012.03.321
Abstract(2089) PDF 1557KB(1092)
The fourth generation comprehensive model of magnetic field CM4 was used to research the variation of external weak field in magnetically quiet periods over Chinese mainland during 1960-2000. The distribution and variation of ionospheric induced field, toroidal field and magnetospheric induced field separated from the external field were also calculated and analyzed. Results show that in terms of lithospheric induced field, component X's trend of variation was increased firstly, then decreased with time, the amplitude is about 7.3nT; Component Y's trend of variation was initially decreased, and increased with time, the amplitude is about 0.8nT; Component Z's trend of variation was increased and then decreased with time, the amplitude is about 5.5nT. The variation amplitude of toroidal field and magnetospheric induced field of three components are relative small. Their distribution during 1960-1970 and 1970-1980, 1980-1990 and 1990-2000 show an interesting phenomenon that areas of positive and negative values exchanged each other, which may has something related with solar 11 years' activities. Finally, analysis and explaination of these results were given.
Study on the ionospheric TEC variations during the total solar eclipse of July 22, 2009
Mo Xiaohua, Zhang Donghe, Qin Jiansheng, Ye Jinfeng, Xiao Zuo
2012, 32(3): 336-342. doi: 10.11728/cjss2012.03.336
Abstract(2360) PDF 581KB(1143)
Variations of the ionospheric Total Electron Content (TEC) during the total solar eclipse of July 22, 2009 was investigated using GPS observed data obtained at five GPS stations (one is in total solar eclipse region, the others are in partial solar eclipse region) in China region. Results indicate that during the total solar eclipse, TEC experiences a decline and recovery process; the delay of a minimum level of TEC with respect to the maximum phase of the eclipse is about 1~10min; the Ionosphere Pierce Point (IPP) of minimum TEC is closer to total solar eclipse region, the decrease of TEC is larger, and during the total solar eclipse, the mean decay TEC compared to the TEC on reference date above WUHN station (114.35°E, 30.53°N) is the maximum, reaching 4.58TECU.
Study on the formation of E-layer ionosphere by means of thermodynamics and statistical physics
Zhang Jing, Wang Jingsong
2012, 32(3): 343-347. doi: 10.11728/cjss2012.03.343
Abstract(2149) PDF 365KB(1072)
Although it is a mature way to discuss thermo-ionization in stellar atmosphere by means of thermodynamics and statistical physics, e.g., the mass action law, the same consideration to photo-ionization is difficult since many conclusions for ideal gases cannot be applied to the photon.By introducing the solar photon as a reactant into the ionosphere photochemical reaction the reaction degree and chemical equilibrium constant in the low ionosphere, and hence the electron density are obtained by means of the chemical thermodynamics method. Meanwhile, the chemical equilibrium constant can be deduced by means of statistical physics method. The results show that the electron density in the lower ionosphere derived by thermodynamics methods is nearly identical with that from the Chapman theory, proves the feasibility to study the ionosphere formation by the thermodynamics methods. However, the two equilibrium constants derived by thermodynamic and statistical physics methods independently are different. Further analysis indicates that not all photon energy is converted to ionization energy in the photochemical process, part of the energy is converted into heat or keeping the particles in the excited states. This difference hints a possibility to derive the ionospheric plasma temperature.
Research on artificial airglow during ionospheric modification by the release of SF6 gas
Huang Yong, Cheng Li, Zhang Fang
2012, 32(3): 348-353. doi: 10.11728/cjss2012.03.348
Abstract(2200) PDF 470KB(1488)
Release of a chemically reactive gas such as SF6 into the ionosphere region can disturb its plasma environment. In this paper, in terms of diffusion equation of SF6 gas and mainly ion-chemistry reactions in ionosphere region, the density changes of ionospheric particles response to the release of SF6 gas are investigated, and the airglow volume emission rates and intensity from the SF6 gas released at ionospheric altitudes are calculated. The results show that the diffusion of released SF6 gas in ionospheric is very quick, and these SF6 gas molecules can cause a large scale depletion of ionospheric electron and O+ density, and the dominate negative ion of ionospheric region is converted into SF5-. During the releasing, the 777.4nm and 135.6nm airglows will be excited, the intensity of 777.4nm is much weaker, and the ionospheric temperature may play an important role in the airglow intensity. Comparing the results of our calculations with American IMS/SF6 experimental data, it shows good agreement, and the temperature of experiment local ionosphere can be exactly estimated through this comparison.
Study on the forecasting method of relativistic electron flux at geostationary orbit based on support vector machine
Wang Renzhong, Shi Liqin
2012, 32(3): 354-361. doi: 10.11728/cjss2012.03.354
Abstract(2013) PDF 576KB(1053)
In this paper the Support Vector Machine (Classification/Regression) is applied to predict the relativistic electron flux at geostationary orbit. The parameters of model are chosen by Mean Impact Values (MIV), including the electron flux, solar wind speed, solar wind density, Dst index on the previous day and AE index during the preceding two days. This model forecasts the level of relativistic electron flux event and the magnitude of electron flux on the coming day. Based on the comparison with original data in 2008, this model can normally categorize active and quite intervals. For predicting the magnitude of relativistic electron flux, the linear correlation coefficient and prediction efficiency is 0.85 and 0.71; and the model can correctly predict the level of energetic electron enhancement event at most of the time (82%). Our result demonstrates this forecasting technique based on SVM is viable and maybe applicable to other subjects.
Research on space-based global atmospheric wave imager
Qian Haojun, Hu Xiong, Tu Cui
2012, 32(3): 362-367. doi: 10.11728/cjss2012.03.362
Abstract(1965) PDF 521KB(981)
Space-based airglow imaging observation is significant for monitoring global atmospheric waves in the mesopause region. The Time Delay and Integration Charge Coupled Device (TDICCD) is used to capture images of O2A (0-0) airglow. The required exposure time and the signal-to-noise ratio are calculated, and the latitude-dependent space resolutions are analyzed with a modulation transfer function. Due to the Earth's rotation, for a circular orbit with a height of 700km and an incline angle of 73°, the spatial resolution increases with in creasing latitudes, which is 5.7km near the equator. Based on the above analysis, the instrument's block diagram is also given. Results indicate that the space-based airglow imager can observe atmospheric waves with a vertical wavelength of approximately 10km or longer and with the best horizontal spatial resolution of 0.33km.
Numerical investigation on influence of micro-gravity magnitude on phase distribution and liquid turbulence statistics in bubbly flow
Pang Mingjun, Wei Jinjia, Yu Bo
2012, 32(3): 368-375. doi: 10.11728/cjss2012.03.368
Abstract(2286) PDF 682KB(1141)
In view of a wide application prospect of bubbly flows in space, it is necessary to deeply understand the influence of microgravity magnitude on the phase distribution and liquid turbulence. An Euler-Lagrange model was developed and used to investigate the influence of the microgravity magnitude on the phase distribution and liquid turbulence. The velocity field of liquid was solved by Direct Numerical Simulations (DNS), and the bubble trajectories were tracked by Newtonian equation of motion. The results show that the bubble distribution and liquid turbulence have a direct relation with the microgravity magnitude. For the computational case with a relatively low gravity magnitude, bubbles roughly uniformly disperse in the channel, and the injection of bubbles has almost no influence on the liquid turbulence. However, when the gravity magnitude is relatively high, most of bubbles accumulate near the wall, and the liquid turbulence is greatly modulated due to the injection of bubbles.
Effects of microgravity on the characteristics of single bubble growth
Yang Yan, Pan Liangming, Wei Jinghua
2012, 32(3): 376-382. doi: 10.11728/cjss2012.03.376
Abstract(2124) PDF 773KB(1185)
Based on the previous experiment and the VOF (Volume of Fluid) multiphase model, the growth characteristics of a single bubble was numerically investigated, on the condition of micro-gravity, for the section size of 10mm × 10mm × 25mm rectangular channel of pool boiling. The transportation of mass and energy during the phase change is implemented by adding source term to the mass and energy equations with User Defined Function (UDF). The results show that under the microgravity condition, the streamline and the temperature field distribution around the bubble have difference; due to surface tension, the bubble under microgravity and normal gravity are different from the bubble detachment; under the condition of microgravity, the change of bubble diameter is more complex, and the heat transfer coefficient fluctuate, the increase of microgravity will enlarge the amplitude of fluctuations.
Numerical study on flow patterns and void fraction distribution in gas-liquid two-phase flow in horizontal pipe under different gravities
Liu Xiangdong, Chen Yongping, Zhang Chengbin, Shi Mingheng, Hao Yingli
2012, 32(3): 383-390. doi: 10.11728/cjss2012.03.383
Abstract(2075) PDF 738KB(1087)
Based on the VOF (Volume of Fluid) method, a three-dimensional unsteady mathematical model is developed to study the gas-liquid two-phase flow in horizontal pipe under different gravities of 10-4g0, 0.17g0, 0.38g0 and 1g0 (g0=9.8m·s-2). The flow patterns and their transitions are numerically investigated by the developed model and the void fraction distribution and oscillation are presented. The results indicate that the characteristics, such as flow patterns, void fraction, and slip ratio, of gas-liquid two-phase flow under different gravities can be well predicted by the developed model. Under the same two-phase superficial velocity, the gas phase accumulates and coalescences in the upper part of horizontal pipe with increasing gravity, resulting in the transition of flow patterns. In addition, with increasing gravity, the slip ratio increases while the peak and frequency of section void fraction oscillation decrease. However, due to that the increasing two-phase superficial velocity enhances the inertia force of two-phase flow, the gravity effects are weakened.
Orbit design and scientific exploration event analysis of Yinghuo-1
Zheng Jianhua, Guo Shishu, Wu Xia, Li Xiaoyu, Zhang Yiteng
2012, 32(3): 391-397. doi: 10.11728/cjss2012.03.391
Abstract(2451) PDF 733KB(1021)
The orbit of Yinghuo-1 is designed for the 2011 launching window with the patched conic approximation method. Then, the orbit characteristics of Yinghuo-1 around Mars, such as the time for Yinghuo-1 flying into the Mars shadow and the time of the sun outage when Yinghuo-1 can not communicate with the Earth, are analyzed. Moreover, the events and time for Yinghuo-1 to pass by the bow shock and the magnetic pileup boundary of the Mars are given. It also shows the time for CCD imager to take pictures of Mars and Phobos, the time for X-band transmitter to do the Mars Radio Occultation Experiment (MROE) with deep ground stations, and the time for the radio occultation receiver in Yinghuo-1 to do the MROE with USO experiment on board of Phobos-Grunt spacecraft. The results of simulation demonstrate that there are many scientific exploration events during one-year flight around the Mars after Yinghuo-1 separates from Phobos-Grunt.
TLE accuracy analysis and conjunction prediction
Li Dawei, Liu Jing, Zhang Yao
2012, 32(3): 398-404. doi: 10.11728/cjss2012.03.398
Abstract(2259) PDF 470KB(1179)
Two Lines Elements (TLE) were widely used for on-orbit conjunction prediction. The accuracy of TLE data had great impact on conjunction prediction results, and was one of the necessary parameters for collision probability calculation. Only if the predicted position accuracy of TLE data were calculated exactly, the value of collision probability is reliable. In the research, the TLE position accuracy was calculated based on two kinds of criterion data, including updated TLE data and Consolidated Prediction Format (CPF) data, whose predicted position was more accurate than TLE data. The TLE position accuracy based on CPF data was used for true TLE position accuracy. Besides, both CPF data and TLE data were used for calculating conjunctions of satellites. CPF data was used for validating the conjunction results calculated based on TLE. The results of the research showed that the position accuracy based on updated TLE data was a little smaller than the true value. So in general cases, the collision probabilities were a little higher, which could be one reason for why conjunction predictions based on TLE were contained of a lot of fake results. With TLE data position accuracy based on CPF instead of updated TLE data, the conjunction results calculated with TLE data might be more reasonable.
Precise orbit determination for GEO satellites based on both satellite clock offsets and station clock offsets
Guo Rui, Liu Li, Li Xiaojie, Cheng Yue, Chang Zhiqiao
2012, 32(3): 405-411. doi: 10.11728/cjss2012.03.405
Abstract(2167) PDF 491KB(1208)
Because of its dynamical features, orbit parameters of the Geostationary satellite (GEO) are strongly correlated with clock offset parameters in Precise Orbit Determination (POD) when using the L-band pseudorange data. In order to solve this problem, clock offsets of the satellite clock as well as the receiver clock are introduced, which are obtained by unattached observation technology. Therefore, the pseudorange data could be converted to ranging data. This paper discussed the GEO POD principle based on pseudorange data with the support of clock offsets, and analyzed the POD accuracy using simulation data from China regional tracking network. Influences from the clock offsets a2 item and errors of the satellite clock offset, stations' clock offsets and systematic errors were analyzed both theoretically and quantitatively.
Detection of space target orbit maneuver on board by wavelet analysis
Su Jianmin, Dong Yunfeng
2012, 32(3): 412-416. doi: 10.11728/cjss2012.03.412
Abstract(2054) PDF 449KB(1135)
It is difficult to detect an orbit maneuver of space target with measurement noise. Orbit maneuver brings step of mechanical energy. Mechanical energy difference of unit mass between space target and spacecraft is treated as signal of maneuver detection, so spacecraft orbit determination error won't be added to the signal. In fact, the mechanical energy difference is only determinate by orbit radius of reference spacecraft and relative position and velocity between reference spacecraft and target. Wavelet analysis in differential scale was used to process the signal with noise. The signal has obviously step feature, and Harr wavelet function was selected in wavelet analysis because of its step feature which is same to the signal. Data after wavelet analysis was used to detect orbit maneuver. In the data process, a valve value is necessary. To some special orbit, we got the valve value through many simulations at first. The data process method which detect orbit maneuver of space target is verified by computer numerical simulation. The simulation shows that the correct rate of the detection of orbit maneuver raise when the maneuver level increase. The method can be used on board because it is automatic completely.
Nonlinear feedback control of fractionated spacecraft electromagnetic formation flying in low-Earth orbit
Hu Min, Zeng Guoqiang, Dang Zhaohui
2012, 32(3): 417-423. doi: 10.11728/cjss2012.03.417
Abstract(2243) PDF 607KB(1279)
A method for designing the nonlinear feedback control law is proposed in this paper for the electromagnetic formation flying system of fractionated spacecraft in low Earth orbit. Firstly, the magnetic force model and the Earth's magnetic field model are established, respectively. The effects of the Earth's magnetic field on the electromagnetic formation flying system in low Earth orbits are analyzed. Secondly, the high precision relative orbit dynamics model is presented. Then, a nonlinear feedback control law for relative orbit is proposed based on the Lyapunov's stability theorem. Finally, two fractionated modules electromagnetic formation maintenance scenario is simulated. The simulation results show that the magnetic disturbance force can be ignored; but the disturbance torque cannot be ignored. Furthermore, the fractionated spacecraft electromagnetic formation flying is fully controllable and the approaches proposed are feasible.
Analysis of solar pressure perturbation impacting on satellite attitude-orbit coupling
Cui Wen, Wang Jiasong, Baoyin Hexi
2012, 32(3): 424-429. doi: 10.11728/cjss2012.03.424
Abstract(2560) PDF 497KB(1343)
With the increasing precision of satellite geodesy, the precision of satellite orbit determination should be improved correspondingly. Currently, the orbit accuracy of Topex, Jason-1, Jason-2 and a series of marine geodetic satellites has already reached a centimeter level. Thus, the satellite dynamics model should also be further improved. Considering the solar array with regular rotation, simplifying the geometry of satellite as Boxing-Wing model which is common in high-precision orbit determination, the solar radiation pressure and moment of Topex satellite are calculated in orbit. Considering the situation of satellite attitude-orbit coupling, the changing of orbital semi-major axis and the satellite attitude caused by the solar pressure perturbation are analyzed. During the calculation of one orbital period, the effect by solar pressure for orbital semi-major axis is about 9cm, and for roll angle and pitch angle both are about 6 degrees, which should not be ignored in high-precision orbit calculations and attitude control.
Analysis of probability of the upset events on Fengyun-2C
Yan Xiaojuan, Xue Bingsen
2012, 32(3): 430-434. doi: 10.11728/cjss2012.03.430
Abstract(1933) PDF 420KB(941)
It is widely known that satellites on geosynchronous orbit are suffering from the energetic electrons in the outer radiation belt which not only make dose effect but also cause the deep charging effect. There have been many reports on the failure of satellites that point to the deep changing effect. Although the geosynchronous orbit is not in the core region of the outer radiation belt and the flux of energetic electron is lower than that of medium Earth orbit, the satellites here always receive the bombardment of the electrons which meet the condition of deep charging effect, especially during the energetic electron storm. In recent years, as more and more sensitive electronic parts are used in the satellite, malfunctions and failures on geosynchronous satellites have become much popular, including Chinese meteorological satellites, namely Fengyun-2 satellites. According to comparison of the data of high energy electrons in geosynchronous orbit from GOES and the upset events on Fengyun-2 satellite, it is shown that all of the upset events on Fengyun-2 satellite occurred during the period of the high energy electron flux increasing, and the upset events is related with deep dielectric charging caused by high energy electrons. In this paper, statistic work that analyze the distribution of the upset events on Fengyun-2 satellite occurred from January 2005 to June 2008 was carried out. It was found that the high energy electron flux enhancement happened periodically, and a model for such distribution of the upset events with the high energy electron flux increasing events is established. The model gives a method to calculate the probability of the upset events through statistical result of the occurrence of the upset and the high energy electron flux enhancement.
Research on XNAV algorithm with correction of pulsars position error
Deng Xinping, Zheng Jianhua, Gao Dong
2012, 32(3): 435-439. doi: 10.11728/cjss2012.03.435
Abstract(2154) PDF 440KB(988)
The essential of the X-ray pulsar navigation (XNAV) is the accurate measurement and transfer of time. Pulsars position error is one of the most important factors affecting the precision of time transfer, so it is one of the most important factors which affect the precision of XNAV. By combining pulsars position with spacecraft position and velocity, a new navigation algorithm is proposed. Results show that the effect of the pulsars position error in XNAV is well dealt by this algorithm, so the new algorithm is referable to the application of XNAV.
Image quality assessment for Chang'E-1 IIM 2C data
Liu Bin, Ling Zongcheng, Liu Jianzhong, Zhang Guangliang
2012, 32(3): 440-448. doi: 10.11728/cjss2012.03.440
Abstract(2107) PDF 800KB(1228)
Imaging Interferometer (IIM) onboard Chang'E-1 satellite is the first imaging spectrometer for lunar detection in China. The multi-bands image data of IIM played an important role in lunar minerals and elements retrieval. In this paper, IIM data is evaluated from several aspects including subjective image visual evaluation, objective image quality parameters, geometric precision, data quality change with time, etc. Subjective visual evaluation shows that images of short wavelength bands (band 1, 2, 3, 4, 5) and the last bands (band 31, 32) in image cube had bad qualities, which may not recognize lunar surface very well, while images in the middle of the cube are much better. A phenomenon is found by RGB image that there is an image tone inhomogeneity from left to right, which may be caused by discontinuity of CCD response. IIM data (band 24) is compared with Clementine UV-VIS image data (band 2) by image evaluation parameters such as radiance precision, definition and information content. Results show that IIM data's definition is better than Clementine UV-VIS, but its radiance precision and information content parameters are inferior. IIM data and Clementine UV-VIS data are normalized to the same spatial resolution and IMM's registration precision is compared. The biggest error of control points' registration is only 0.63pixel. Besides, IIM images acquired at different time covering the same district of lunar surface were compared and evaluated through parameters of radiance precision, definition and information content, and the time span is two months. The parameters calculated are very close, illustrating that the instrument worked stably at that period.
Analysis of the system linearity caused by gain variation of satellite-borne microwave radiometer
He Jieying, Zhang Shengwei, Zhao Jin, Zhang Yu
2012, 32(3): 449-454. doi: 10.11728/cjss2012.03.449
Abstract(2022) PDF 441KB(1079)
The characteristics analysis of diode detector of satellite-borne microwave radiometer has been described. In this paper, given a certain observation target, the retrieved brightness temperatures changed correspondingly with the different values of system Automatic Gain Control (AGC). By adjusting the system gain, a little change happened for detector working range. The variation caused by nonlinearity of diode can not be completely eliminated by using two-point calibration method. The brightness temperatures retrieved in this paper are in a wide range of 3~350K. The experimental results demonstrate that there is obvious nonlinearity for brightness temperatures between retrievals minus actual values and observing values, which can not be eliminated by using two-point calibration. So, in the process of working and real-time calibration, the system must be assured working in approximately linear working range with a certain AGC value as possible.
Electronic interface of a mini-type ultraviolet-visible spectrometer
Yu Qiang, Yu Chun, Zhai Guangjie, Zhou Binghong, Liu Weifeng
2012, 32(3): 455-460. doi: 10.11728/cjss2012.03.455
Abstract(1640) PDF 531KB(1071)
A kind of Ultraviolet and Visible Light Optical Spectrum Instrument (UVLOSI) is introduced. This facility is characterized with light weight, small volume and low power consumption, which is suitable to be utilized in space. Meanwhile, an interface scheme for connecting the UVLOSI with space biologic capsule control system is presented. Following this scheme, an interface circuit is designed, and the data of the UVLOSI is successfully transferred to the center controller in space biologic capsule. Using this method, the measurement data of the UVLOSI in the system control panel can be directly observed. The interface communication protocol (RS232) between the UVLOSI and the interface circuit is presented. After that, the interface communication protocol (CAN2.0B) between space biologic capsule control system and the interface circuit is described. At last, measurement results of the UVLOSI are given.