Table of Content

    15 December 2014, Volume 35 Issue 1 Previous Issue    Next Issue
    Simulation of three-dimensional Earth's bow shock
    Hu Huiping, LÜ Jianyong, Zhou Quan, Wang Ming, Yang Yafen, Liu Ziqian, Pei Shixin
    2015, 35 (1):  1-8.  doi: 10.11728/cjss2015.01.001
    Abstract ( 1216 )   PDF (2276KB) ( 1265 )   Save

    We use a physics-based global Magnetohydrodynamic (MHD) model to investigate the location and shape of the Earth's bow shock. The bow shock locations in the simulations are identified by an automated search algorithm and is fitted by simple analytical functions. A global three dimensional bow shock model is constructed to include the effect of magnetopause and is parameterized by the fast magnetosonic Mach number, solar wind ram pressure, interplanetary magnetic field strength, and magnetopause curvature radius. The model results are compared and agree well with the previous empirical and simulation models. We also find that both the shock standoff distance and the shock flaring angle decrease monotonically with increasing the fast magnetosonic Mach number. The size and location of bow shock on the equatorial plane and the meridian plane show obvious asymmetry.

    References | Related Articles | Metrics
    Splitting based scheme for three-dimensional MHD with dual time stepping
    Fu Huazheng, Feng Xueshang
    2015, 35 (1):  9-17.  doi: 10.11728/cjss2015.01.009
    Abstract ( 871 )   PDF (3927KB) ( 1460 )   Save

    A new hybrid numerical scheme of combining an E-CUSP (Energy-Convective Upwind and Split Pressure) method for the fluid part and the Constrained Transport (CT) for the magnetic induction part is proposed. In order to avoid the occurrence of negative pressure in the reconstructed profiles and its updated value, a positivity preserving method is provided. Furthermore, the MHD equations are solved at each physical time step by advancing in pseudo time. The use of dual time stepping is beneficial in the computation since the use of dual time stepping allows the physical time step not to be limited by the corresponding values in the smallest cell and to be selected based on the numerical accuracy criterion. This newly established hybrid scheme combined with positivity preserving method and dual time technique has demonstrated the accurateness and robustness through numerical experiments of benchmark problems such as the 2D Orszag-Tang vortex problem and the 3D shock-cloud interaction problem.

    References | Related Articles | Metrics
    Fluctuations of high-energy electron fluxes in Earth's radiation belt and its applications for geomagnetic storm alert
    Huang Wengeng, Shen Hua, Liu Siqing, Zhong Qiuzhen, Chen Yanhong
    2015, 35 (1):  18-25.  doi: 10.11728/cjss2015.01.018
    Abstract ( 911 )   PDF (5327KB) ( 1154 )   Save

    The outer radiation belt consists mainly of high energy electrons trapped by the Earth's magnetic field. The disturbance of the geomagnetic field caused by the Coronal Mass Ejection (CME) or the Co-rotating Interaction Region (CIR) can result in electron radiation belt variations. According to the variation feature of high energy electron flux in the outer radiation belt during magnetic storms, a novel index referred to as high electron flux fluctuation index was evaluated by using the 5-min resolution sampled electron flux data provided by GOES, and its correlation with geomagnetic Kp index was analyzed. It is found that high electron flux fluctuation index has a good correlation with geomagnetic Kp index, and the new index can be used as an indicator of geomagnetic storm occurrence. In comparison with 3-hour Kp index, which is wildly used in space environment operation prediction system, the suggested index in this paper can alert geomagnetic storm occurrence earlier.

    References | Related Articles | Metrics
    New regional geomagnetic activity index based on multi-station observation
    Wang Chuqin, Du Dan, Zhang Xiaoxin, Zhao Mingxian, Jiang Yong
    2015, 35 (1):  26-39.  doi: 10.11728/cjss2015.01.026
    Abstract ( 813 )   PDF (2896KB) ( 1169 )   Save

    With the data of 14 geomagnetic observatories in China and 23 geomagnetic observatories abroad, both temporal and spatial variation characteristics of rH index are analyzed. And the 14 geomagnetic observatories in China are divided into 7 regions by using K-means clustering algorithm based on the similarity measurement, and the residual index (Ra) of rH index between each two observatories. Then the regional rH index (Rr) of each region is calculated by linear weighted sum method. The results show that rH has a periodic change in 27 days, which is the solar rotation cycle. Although no significant seasonal variation is found in rH, it is also shown that the average of rH in spring and autumn is greater than in summer and winter. For spatial variations, rH increases with the latitude. There are some obvious difference in amplitude and morphology of rH during geomagnetic storms, and the feature of dusk-dawn asymmetry is found. Comparison with the observational data of H component and other Global geomagnetic activity indices, such as Dst, SYM-H and Kp, indicate that Rr can reflect the regional geomagnetic disturbance effectively.

    References | Related Articles | Metrics
    Seasonal distribution of ozone and radiation field at the stratosphere
    Shang Lin, Liu Yi, Wang Yong, Tian Wenshou
    2015, 35 (1):  40-49.  doi: 10.11728/cjss2015.01.040
    Abstract ( 852 )   PDF (2574KB) ( 1450 )   Save

    The coupled chemistry-climate model WACCM3 (Whole Atmosphere Community Climate Model) developed by NCAR is applied to study the seasonal variations of the stratospheric temperature, wind, ozone and radiation fields. The stratospheric quasi-zero wind layer at around 20~22km (i.e., atmosphere pressure range is 50~30hPa), where the wind speed is less than 5m·s-1 and is stable to the north of 40°N during July and August, is suitable for long-term stay of airships. There appears a belt of ozone at 30hPa over China and ozone concentrations are greater in the mid-latitudes than in the lower latitudes below 30hPa. There are significant seasonal spatial variations in solar heating rates in the stratosphere. In the upper stratosphere, the maximum solar heating rate reaches 100×10-6K·s-1 while in the lower stratosphere the maximum solar heating rate is only 10×10-6K·s-1. The solar heating rate is greater in June to August than in September over China. The solar heating rate is greater in the mid-latitudes than in the lower latitudes between 100hPa and 30hPa and is greater in the lower latitudes than in the mid-latitudes above 30hPa. The change of solar heating rate is small in August and September at 30hPa and 40hPa. The maximum diurnal variation of solar heating rate appears at 40°N at 30hPa. At 50hPa, the diurnal variation of solar heating rate is smaller than that at 40hPa and the maximum variation occurs farther south. The longwave heating rate is smaller in the lower latitudes than in the mid-latitude stratosphere. In particular condition of terrain, the ozone concentration, solar heating rate and longwave heating rate are smaller over Tibetan Plateau than other areas at the same latitude.

    References | Related Articles | Metrics
    Research of EASM decadal variation characteristics based on the EMD method and the relationship with solar activity
    Jiang Qiongfei, Guo Shengli, Liang Haowen, Wu Shanwei, Su Yucheng
    2015, 35 (1):  50-55.  doi: 10.11728/cjss2015.01.050
    Abstract ( 751 )   PDF (964KB) ( 1171 )   Save

    By application of normalization of the SLP data from Hadley and NCEP/NCAR, the East Asian Summer Monsoon (EASM) index from 1850 to 2011 are obtained. EMD method is adopted to analyze the periodic characteristics and get the EASM index cycles on various time scales. With three times analyses, the 11-year cycle component is obvious and has the highest correlation with the original data. Both the sunspot activity and the EASM activity have the same cycle component of 11-year and 80-year, especially the 11-year cycle component is obvious. With comparison between 11-year cycle component of sunspot number and that of EASM index, both of the fluctuation amplitude changes are basically identical.

    References | Related Articles | Metrics
    Radiation dose evaluation and analysis inside FY-3A satellite
    Wang Chunqin, Sun Yueqiang, Cao Guangwei, Zhang Xianguo, Li Jiawei, Zhang Xiaoxin, Jing Tao, Shen Guohong, Zhang Shenyi, Huang Cong, Liang Jinbao, Shi Chunyan, Han Ying
    2015, 35 (1):  56-63.  doi: 10.11728/cjss2015.01.056
    Abstract ( 792 )   PDF (2844KB) ( 1445 )   Save

    FY-3A satellite can measure the radiation dose data from different directions during the missions from 2008 to 2012. In this paper, we describe total radiation dose from two directions, and dose rate variation with energetic particle flux. The result shows that different sections of the spacecraft receive different amounts of radiation dose, which is always consistent with space distribution of energetic particles. Absorbed dose rate changed greatly from several rad (Si)·d-1 during quite time to even more than tenfold during disturbances. The increased high energy electrons in polar regions during disturbances are responsible for significant increase of radiation dose. At last, FY-3A radiation dose during the operational period of the mission is compared with the results calculated by SPENVIS. It is obvious that observation data is more realistic to reflect the real space radiation environment.

    References | Related Articles | Metrics
    Analysis of single-event effects rate of K6R4016V1D chips applied in low Earth orbit
    Han Jianwei, Feng Guoqiang, Yu Yongtao, Ma Yingqi, Shangguan Shipeng, Chen Rui, Zhu Xiang
    2015, 35 (1):  64-68.  doi: 10.11728/cjss2015.01.064
    Abstract ( 775 )   PDF (1292KB) ( 1163 )   Save

    Russia's Mars probe Phobos-Grunt together with China's first Mars probe Yinghuo-1 were launched into Low Earth Orbit (LEO) on November 9, 2011. Unfortunately, the main probe failed to fire its thrusters and transfer its orbit as planned after 159 minutes, eventually the trip to Mars was terminated. The most likely cause of the accident investigated by Russian Space Agency (RSA) was that RAM chips in onboard control computers worked wrong when hit by cosmic heavy charged particles, which sequently led to the two computers restart and eventually disturbed the probe totally. However experts on satellite radiation hardness casted lot of doubt on the statement that LEO probe can be effected by Single-Event Effects (SEE) resulting from space radiation particles in so short period of time. Based on information of the victim RAM components disclosed by RSA, experiment tests and calculations were performed for K6R4016V1D chip to predict SEE rate when applied in LEO. Finally, possibility for SEE to cause the failure of Phobos-Grunt probe was discussed.

    References | Related Articles | Metrics
    Numerical Investigation of Aerodynamics on Low Earth Orbit Satellite
    HUANG Fei, ZHAO Bo, CHENG Xiaoli, LÜ Junming
    2015, 35 (1):  69-76.  doi: 10.11728/cjss2015.01.069
    Abstract ( 816 )   PDF (5110KB) ( 1007 )   Save

    DSMC code is validated with GOCE satellite free molecule aerodynamics data in\linebreak reference. The difference of GOCE satellite flow field and aerodynamic characteristics computed with different wall reflect coefficient is shown. Results show that the drag force coefficient computed by present code is in good agreement with that of the reference. When the wall reflection coefficient is changed from 0.1 to 1.0, the pressure distribution at the local stagnation and wing head region is shown to change from banded structure to ellipse structure. With the wall reflection coefficient increasing, the friction drag coefficient increases, and the pressure drag coefficient decreases, which results in that the total drag coefficient increases firstly, decreases then, and reaches its maximum when the wall reflection coefficient is about 0.8.

    References | Related Articles | Metrics
    Theoretic Analysis on a New Technique of Dust-based Active Debris Removal
    LI Yiyong, CHEN Yong, LI Zhi, JIA Yongsheng
    2015, 35 (1):  77-85.  doi: 10.11728/cjss2015.01.077
    Abstract ( 1007 )   PDF (2300KB) ( 1302 )   Save

    It is believed that the number of debris located near Low Earth Orbit (LEO) has approached the tipping point, which is the threshold for collision cascade. The Active Debris Removal (ADR) has come to be very necessary. Method on a new technique for cleaning space junk at the low earth orbit through dust-based ADR system has been proposed and researched by the U.S. Naval Research Laboratory. In this paper, special theoretical analysis on the new method is made. Firstly, the basic hypothesis and interaction mechanism models between single fraction and artificial dust are built, and the interaction results are calculated and analyzed quantitatively. Then, space debris density distribution is analyzed, the action effect of the new method is studied, and some basic conclusions are obtained. These results will help to understand the new method objectively.

    References | Related Articles | Metrics
    Research on Formation Initialization Control for Elliptic Reference Orbit
    LEI Bochi, ZHENG Jianhua, LI Mingtao
    2015, 35 (1):  86-93.  doi: 10.11728/cjss2015.01.086
    Abstract ( 714 )   PDF (2010KB) ( 1154 )   Save

    Formation initialization for elliptic reference orbit is studied in this paper, and three formation initialization strategies for planner formation configuration are derived. Firstly, two impulsive initialization strategy is derived using the state transition matrix. Secondly, three and four in-track impulsive initialization strategies are studied using the Gauss perturbation equations with the principle of minimal fuel consumption. Finally, numerical simulations of three initialization strategies are carried out, and the sequence quadratic programming and genetic algorithm are proposed to optimize the numerical results. Simulation results show that three in-track impulsive initialization strategy requires about 41% less velocity increment compared with two impulsive initialization strategy, and four in-track impulsive initialization strategy requires almost equal velocity increment compared with three in-track impulsive initialization strategy.

    References | Related Articles | Metrics
    Constellation Design for Geosynchronous Belt Surveillance System Based on the SBV Sensor
    TANG Yi, ZHONG Wenan, SHOU Junming, LI Shuang
    2015, 35 (1):  94-103.  doi: 10.11728/cjss2015.01.094
    Abstract ( 1062 )   PDF (4558KB) ( 1185 )   Save

    The constellation configuration of the surveillance system was analyzed and designed, under the background of monitoring the entire geosynchronous belt using the Space-Based Visible (SBV) sensor. Firstly, the optimal observation model was extracted based on summarizing the merits and weak points of the three observation models. Secondly, relationship between the orbit altitude of the surveillance satellite and parameters of the search fence was deduced, and the numeric area of orbit altitude was derived. Thirdly, the principle of distribution of optimal observation period and imaging time for SBV sensor were extracted, based on analyzing the influence factors. Finally, the principle of selection for the satellite number of surveillance system and the size of the search fence, and the numeric area of orbit altitude of two-satellite surveillance system which satisfied the requirement of regressive orbit characteristic were extracted, based on analyzing the percentage of coverage and observational frequency for the single-satellite and two-satellite surveillance system. The results indicate that the ability of coverage for geosynchronous object which has a large inclination is improved when the surveillance satellite crossing the celestial pole and using pinch points observation model. The orbit of surveillance satellite is sun-synchronous circle orbit which local time of descending node at 06:00LT or 18:00LT, altitude from 615km to 850km, and around this range there are 6 piece regressive orbits.

    References | Related Articles | Metrics
    Research of the front-end signal processing circuit for the magnetospheric electric field instrument
    Hu Yun, Zhou Bin, Zhao Hua
    2015, 35 (1):  104-109.  doi: 10.11728/cjss2015.01.104
    Abstract ( 600 )   PDF (1019KB) ( 996 )   Save

    A kind of front-end signal processing circuit of the electric field instrument, which would be used in the Earth's magnetosphere measurement, is investigated and presented in this work. The double-probe electric field instrument outputs drive current to the ambient plasma environment, and measures the potential difference between the two probes to detect the electric field. Plasma impedance of the magnetosphere is high, so the probe of the electric field instrument will operate in a high voltage to match the electric current requirement. When the operating voltage is close to or surpasses the circuit threshold voltage, the measuring results would be affected, and the instrument will be possibly damaged. This paper adopts voltage scheme with low bias current and feedback floating power supply control scheme, to solve the weak current sampling problem and high dynamic potential handling problem in measuring the electric field of a thin plasma. Test results show that the circuit can make the probe adapt to the floating ground in the dynamic voltage range of ±100V, and measure the electric field from DC to 150kHz, with a low noise level below 14nV·mHz-1/2, which meets the needs of electric field measurements in magnetosphere.

    References | Related Articles | Metrics
    Design of High-speed Readout Circuit for Far Ultraviolet Photon-counting Imaging Detector
    LIU Xiaohong, WANG Yongmei, WANG Yongsong
    2015, 35 (1):  110-115.  doi: 10.11728/cjss2015.01.110
    Abstract ( 563 )   PDF (2089KB) ( 1019 )   Save

    The technology of far ultraviolet photon-counting imaging detection is to record each single photon position and achieve the purpose of general imaging by detecting weak single photon information. The counting rate limits the information acquisition. On the basis of analyzing factors affecting the counting rate, the front-end analog circuit is needed for the amplification and shaping of the detector signals. Eventually, A225 chip was chosen as the pre-amplifier and shaping circuit was designed in the analog front-end circuit. Corresponding simulation and experimental results show that the circuit design is reasonable, and the counting rate can reach 200kHz.

    References | Related Articles | Metrics
    Application of Contact Graph Routing in Satellite Delay Tolerant Networks
    ZHU Laitao, LI Yong, ZHANG Junxiang, WU Jing, TAI Xiao, ZHOU Jianguo
    2015, 35 (1):  116-125.  doi: 10.11728/cjss2015.01.116
    Abstract ( 1309 )   PDF (1578KB) ( 2700 )   Save

    Satellite networks have many inherent advantages over terrestrial networks and have become an important part of the global network infrastructure. Routing aimed at satellite networks has become a hot and challenging research topic. Satellite networks, which are special kind of Delay Tolerant Networks (DTN), can also adopt the routing solutions of DTN. Among the many routing proposals, Contact Graph Routing (CGR) is an excellent candidate, since it is designed particularly for use in highly deterministic space networks. The applicability of CGR in satellite networks is evaluated by utilizing the space oriented DTN gateway model based on OPNET(Optimized Network Engineering Tool). Link failures are solved with neighbor discovery mechanism and route recomputation. Earth observation scenario is used in the simulations to investigate CGR’s performance. The results show that the CGR performances are better in terms of effectively utilizing satellite networks resources to calculate continuous route path and alternative route can be successfully calculated under link failures by utilizing fault tolerance scheme.

    References | Related Articles | Metrics
    A Fast calculation method for coverage analysis of space telescope based on coordinates transformation and QTM code
    Yang Zhen, Gao Chen, Niu Wenlong, Meng Xin, Li Dalin
    2015, 35 (1):  126-132.  doi: 10.11728/cjss2015.01.126
    Abstract ( 829 )   PDF (1804KB) ( 1107 )   Save

    In sky coverage analysis, we present an efficient algorithm based on a coordinate transformation method to calculate the points on the boundary of detection field. In this method, the complexity of coordinates transformation is reduced by building a new Celestial Coordinates. Based on this algorithm, QTM, a coding method that has many advantages can be used to manage the data calculated. The main contents of this topic include: to build the quantitative calculation model for sky coverage; to establish the rasterized expression method of sky coverage analysis results; and to verify the method, analyse the accuracy of the method, compare the efficiency with the attitude-matrix transformation method and analytical method.

    References | Related Articles | Metrics