Table of Content

    15 November 2019, Volume 39 Issue 6 Previous Issue    Next Issue
    Simulation of CR2055 Solar Wind with SIP-AMR-CESE Model
    WANG Jing, LI Huichao
    2019, 39 (6):  719-729.  doi: 10.11728/cjss2019.06.719
    Abstract ( 365 )   PDF (2653KB) ( 70 )   Save
    In this paper, the three-dimensional (3D) Solar-Interplanetary (SIP) Adaptive Mesh Refinement (AMR) space-time Conservation Element and Solution Element (CESE) MHD (SIP-AMR-CESE MHD) model is used to simulate solar wind from the solar surface to the Earth's orbit. The model uses a six-component grid system and the PARAMESH software package to implement adaptive mesh refinement. Based on the model, the Generalized Lagrange Multiplier (GLM) was added to eliminate the divergence error of magnetic field in the simulation of solar wind. Heating-method was adjusted so that the model can produce a more distinct fast and slow solar wind structure. An improved grid refinement criterion, accompanied by GLM addition and heating-method adjustment, making the simulation results more consistent with the observations. Moreover, the computational efficiency of the model was improved by controlling the computation range at different times. By using the improved model, the steady state solution of CR2055 solar wind was obtained and it showed a good agreement with the observations. In this paper, we gave some useful methods to make the solar wind simulation more efficient and consistent with the observations. This work is very meaningful.
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    Response of Low-latitude Hainan Ionospheric Plasma Drifts to Geomagnetic Activities
    HONG Yu, WANG Guojun, SHI Jiankui, WANG Xiao, CHENG Zhengwei, WANG Zheng, SHANG Sheping
    2019, 39 (6):  730-737.  doi: 10.11728/cjss2019.06.730
    Abstract ( 315 )   PDF (2379KB) ( 86 )   Save
    The responses of low latitude ionospheric drifts to three levels of geomagnetic activity for high and low solar activities have been investigated by analyzing the plasma drifts data obtained by Meridian Project Hainan station (19.5°N, 109.1°E) during 2003-2016. Results show that the daytime dominant westward drifts do not change much with magnetic activities in all seasons. The near sunrise and nighttime dominant eastward drifts decrease with the increase of magnetic activities and are more significantly in equinox, less in summer. The daytime weakly upward drifts are independent of magnetic activities and seasons. The enhanced sunset upward decrease with magnetic activities only in equinox. The vertical drifts before midnight are suppressed in equinox and reversed in winter for magnetic disturbance, but have no obvious response in summer. The downward drifts from midnight to sunrise are basically reduced with the increase of the magnetic activities in all seasons. The effects of magnetic and solar flux on drifts in Hainan follow closely with Jicamarca. However, there are some differences in amplitude and phase, which may be caused by difference in solar cycle, geographical and detection techniques.
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    Interpolation Evaluation of Ionospheric TEC Based on Autocorrelation Analysis Method
    WANG Jianping, LIU Ruiyuan, DENG Zhongxin
    2019, 39 (6):  738-745.  doi: 10.11728/cjss2019.06.738
    Abstract ( 364 )   PDF (1561KB) ( 90 )   Save
    In the ionospheric TEC monitoring system, there are often multiple, long-term missing values in one day, which have an impact on the study of the spatio-temporal variation characteristics of the ionospheric TEC. Based on the statistical analysis of measured data in 2004, ionospheric TEC interpolation and accuracy evaluation are studied by using of autocorrelation analysis method. Using the data of the Shanghai GPS integrated application network and the Chinese crustal movement GPS monitoring network, it is converted into the vertical TEC of the ionosphere, and the missing values are time-interpolated. The results show that the interpolation error in the missing value segment is generally larger in the middle, while smaller on both sides, and the interpolation error is much smaller than the mean square error. The interpolation results of autocorrelation analysis method are compared with the results of linear interpolation, parabolic method and cubic spline interpolation method. It is found that the accuracy of interpolation is obviously improved for the missing value segment with relatively complex changes. After the interpolation, the jump change caused by the missing value is effectively reduced by the autocorrelation method and the TEC variation characteristics can be studied more accurately.
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    Ionospheric Effects Caused by In-orbit Engine Jet
    ZHAO Haisheng, XU Zhengwen, XU Zhaohui, YUAN Shigeng, LIU Shengli, WU Jian, XU Bin, XUE Kun
    2019, 39 (6):  746-756.  doi: 10.11728/cjss2019.06.746
    Abstract ( 379 )   PDF (3403KB) ( 53 )   Save
    Satellite and other spacecraft need to be operated in a specific space environment, and the change of space environment has important influence on the orbit and life span of spacecraft. During the running of satellite and spacecraft in orbit, specific requirements, such as attitude control and orbit adjustment are implemented by jet. The interactions between the jet and the ionosphere can cause the ionosphere environment change, which may affect the normal work of the spacecraft. In this paper, the kinetics and chemical reactions process of the spacecraft jet are studied, and an ionospheric disturbance physical model of spacecraft jet is set up. The dynamic process, density distribution and ionospheric perturbation effect of different jet weight, jet time and jet altitude are simulated. The simulation results show that, at the same jet height, with the increase of jet weight, the perturbation effect of the ionosphere increases; at the same jet weight, with the increase of jet height, the perturbation effect of the ionosphere gradually weakens and the perturbation area gradually increases. The results are of great significance for the design of spacecraft with maneuverability and the study of physical mechanism and control factors of ionospheric disturbance.
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    Assessment of Thermosphere Models Based on Orbit Prediction
    LIU Wei, GONG Jiancun, LIU Siqing, WANG Ronglan
    2019, 39 (6):  757-763.  doi: 10.11728/cjss2019.06.757
    Abstract ( 440 )   PDF (3917KB) ( 67 )   Save
    The LEO prediction error was studied with thermosphere models including J77, DTM78, MSIS00, JB2008 and the CHAMP derived density. In precise orbit prediction without prior information, the performance of the thermosphere model may be erased by uncertainties of those parameters such as the area mass ratio, and the prediction error cannot be used as the criteria for performance evaluation of those models. The prior information can be used to improve the accuracy of those orbit predictions, especially during the geomagnetic disturbed period. The orbit prediction error is averagely about 10%~25% compared with the situation without prior information. The main defects of thermosphere models exist currently in the geomagnetic disturbed period. The difference between models is that JB2008 model can be compensated by single frequency plus linear items, but J77, DTM78 models can't. This paper introduces new insights to the precise orbit prediction under different conditions, which can be used as tutorial materials to provide reference for the engineering practice of space debris collision warning.
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    Initial Results of Meteor Observations with Langfang MF Radar
    CAI Bing, XU Qingchen, HU Xiong
    2019, 39 (6):  764-769.  doi: 10.11728/cjss2019.06.764
    Abstract ( 497 )   PDF (4985KB) ( 75 )   Save
    Medium Frequency (MF) radars can be used to develop the meteor observations over 100km during night time, and detect the distributions of hourly echo rate, height and angle of arrival. The meteor entrance speeds, meteor radiants and radial drifted velocities can also be determined. These data can be used to study meteor astronomy and middle atmosphere dynamics. The meteor observations in middle latitudes for the first time in China are developed by using of Langfang MF radar (39.4°N, 116.7°E) during 12:00UT-22:00UT on November 16, 2017. The receiving range of the echoes was set from 78km to 150km. The time and height resolutions are 2min and 2km respectively, and the pulse repetition frequency is 80Hz. As a result, totally 94 meteor echoes were obtained with the mean height of 106.5km and the majority of them were distributed from 97km to 115km. Ambipolar diffusion coefficient, angle of arrival and some relevant parameters were simultaneously analyzed using the raw data. The results of the comparison between Buckland Park MF radar meteor observations and Langfang MF radar observations show that the detections of the two radar are mostly consistent.
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    Space Environment Monitor and Preliminary Results of HXMT Satellite
    WANG Chunqin, SHEN Guohong, ZHANG Shenyi, CHANG Zheng, YUAN Bin, SUN Ying, SUN Yueqiang
    2019, 39 (6):  770-777.  doi: 10.11728/cjss2019.06.770
    Abstract ( 483 )   PDF (2037KB) ( 77 )   Save
    Hard X-ray Modulation Telescope (HXMT) was Chinese first space astronomy satellite, which was launched into 550km orbit with inclination of 43° in June 2017. The Space Environment Monitor on HXMT was designed to provide measurements of energetic protons and electrons. The detector is an all solid-state system that can make 16-directional flux measurements of electrons with energy ≥ 200keV and protons with energy ≥ 1.5MeV, and can also measure the differential energy spectra of electrons from 0.4 to >1.5MeV and protons from 3 to 300MeV with 7 channels separately from single direction. The detector can characterize particles distribution for detail especially in SAA which is important for low Earth orbit missions. The primary observations provide relative comprehensive particles global distributions, and demonstrate that particles radiation are mainly observed in SAA within longitude 80°W-20°E and latitude 0°-40°S, and electrons in SAA show stronger anisotropy than protons, the SEP occurred in September 2017 had no effect on the orbit, while the magnetic storm in early time before the SEP induced electrons enhancement in narrow region within longitude 120°W-60°E and latitude 40°-43°N over North America and longitude 60°-120°E and latitude 40°-43°S over South-West Australia. The electrons showed intensive anisotropy.
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    Melting Heat Transfer Characteristics of Liquid Metal as Phase Change Material under Microgravity
    GUO Wenhua, PENG Hao, ZHAO Jianfu
    2019, 39 (6):  778-786.  doi: 10.11728/cjss2019.06.778
    Abstract ( 533 )   PDF (1731KB) ( 95 )   Save
    Thermal energy storage is suitable for temperature control of working units in spacecraft under periodic heat flow, but it faces the problem of low melting rate of phase change materials under microgravity environment. In view of high thermal conductivity and high latent heat per unit volume of liquid metal, it is expected that the melting rate under microgravity will be increased by using liquid metal as phase change material. In the present study, the evolution of solid-liquid interface, streamline profile and temperature distribution during melting of gallium under microgravity are numerically investigated, and the influences of cavity size and superheat degree on melting process are analyzed. The results show that heat conduction plays a dominant role in the melting process of gallium under microgravity. The melting time of gallium is 88.3% and 96.4% shorter than that of ice and n-octadecane respectively, and the energy storage is 1.2 and 2.2 times of that of ice and n-octadecane respectively. The melting time decreases with the increase of superheat degree, and increases with the increase of cavity size. Meanwhile, the equation for describing the relationship between liquid fraction and dimensionless time is deduced.
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    Irradiation Effects on Nano Carbon Materials
    ZHEN Xiaojuan, HUANG Yifan, YANG Shengsheng, FENG Zhanzu, BA Dedong, WANG Jun, ZHUANG Jianhong, YIN Hong
    2019, 39 (6):  787-799.  doi: 10.11728/cjss2019.06.787
    Abstract ( 522 )   PDF (2834KB) ( 135 )   Save
    Carbon nanotubes (CNT) and graphene are emerging materials in the nano carbon family, which have received much attention in recent years for their remarkable physical properties. The excellent electrical, thermal and mechanical properties of CNT and graphene make them to be a promising candidate for aerospace engineering. In the harsh space environment, irradiation effect may cause the damage even failure of spacecraft materials, which is the key factor to determine the application of new nano carbon materials in space engineering. This paper focuses on the recent progress of electron and ion irradiation effect on CNT and graphene. The production and the type of defects, the application of irradiation effect in material preparation and functional modification, the irradiation effect on properties of devices and the space adapt ability are discussed. The irradiation effect on nano carbon composite and the influence mechanism of defects on the properties of nano carbon systems also are discussed. By summarizing the previous researches, the current problems are listed. Finally, the future work in space application is forecasted.
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    SVOM: a Joint Gamma-ray Burst Detection Mission
    YU Shunjing, GONZALEZ Francois, WEI Jianyan, ZHANG Shuangnan, CORDIER Bertrand
    2019, 39 (6):  800-808.  doi: 10.11728/cjss2019.06.800
    Abstract ( 1043 )   PDF (2185KB) ( 172 )   Save
    SVOM (Space-based multi-band astronomical Variable Objects Monitor) is an international cooperation project. It is led by Chinese National Space Agency (CNSA) and Centre National d'Etudes Spatiales of France (CNES). SVOM focuses on the detection of GRB (Gamma-Ray Burst). It is developed by Chinese Academy of Sciences (CAS), CNES and several other French laboratories. With multi-wavelength observation, rapid slew capability, flexible operation and ground follow-up observation, the SVOM project will be the most important GRB detection mission after the SWIFT project and will open a wide exploration field. In this paper, its management, science objectives, satellite platform and payloads, ground segment and operation concept are illustrated.
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    SZ-5 Cabin's Height Changes during Three Super-storms in 2003
    HUANG Cong, LIU Dandan, GUO Jing, ZHANG Xiaoxin
    2019, 39 (6):  809-815.  doi: 10.11728/cjss2019.06.809
    Abstract ( 418 )   PDF (468KB) ( 97 )   Save
    In this work, the daily height variations of SZ-5 (Shenzhou-5) cabin from 22 October to 28 November in 2003 are analyzed, which includes the period of the Halloween Storm and the Great November Storm. The significant orbital decays have been observed at the end of October and in late November due to the great solar flares and the severe geomagnetic storms. According to the equation of the air-drag-force on a spacecraft and the SZ-5 orbital decay information, the relative daily average thermospheric density changes during the three 2003 super-storms are derived and the results are compared with the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended Model (NRLMSISE-00). The results show that the daily average thermospheric density (at the altitude of SZ-5, about 350 km) in storm time enhances to approximately 200% as much as that in the quiet time but the empirical model may somewhat underestimate the average thermospheric density changes and the daily contributions of geomagnetic storms to the density enhancements during these severe space weather events.
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    Effects of Geometry Configurations on Ambiguity Function for Cluster Flight Netted Radar
    XIA Mingfei, HU Shengbo, MO Jinrong, SHI Yanfeng, YAN Tingting, LEI Tao, QIN Chanchan
    2019, 39 (6):  816-823.  doi: 10.11728/cjss2019.06.816
    Abstract ( 298 )   PDF (1442KB) ( 56 )   Save
    Network radar is composed of several space-separated, independent and cooperative radars. Compared with traditional single base station radar and dual base station radar, network radar has many advantages. In this paper, the concept of cluster flight netted radar integrated of the cluster flight spacecraft and the netted radar is proposed. The geometry of bistatic radar, the geometry of near-circular orbit cluster flight bistatic radar and the topology model of near-circular orbit cluster flight netted radar are calculated. The definition and calculation steps of the ambiguity function for the cluster flight netted radar are given using the ambiguity function for the conventional bistatic radar. The effects of geometry configuration and the variable baseline on ambiguity function are presented. The numerical calculation shows that the main lobe width of the ambiguity function of the netted radar is obviously narrowed compared with the single radar, and the variable baseline has little influence on the radar ambiguity function. The radar ambiguity function is mainly affected by the target flight speed and the distance. Finally, an upper bound of ambiguity function of cluster flight netted radar is given.
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    Analyses on Self-reduce Liquid Sloshing in Double Tank
    LIN Kecheng, SONG Xiaojuan
    2019, 39 (6):  824-830.  doi: 10.11728/cjss2019.06.824
    Abstract ( 441 )   PDF (3800KB) ( 72 )   Save
    Researches have shown that when spacecraft is in orbit, liquid fuel sloshing is one of the main factors that destroy the stability of spacecraft and threaten the safety of space missions. It is necessary to take research on liquid sloshing. Self-reduce sloshing is common in spaceflight missions, which is more complex than enforced sloshing. In this paper, the self-reduce sloshing characters of liquid fuel in the double parallel tanks are studied by FLUENT software and calculation formulas. Based on the Finite Volume Method and the two-phase laminar flow model, the effects of sloshing force, torque and wave height which liquid fuel acts on the tank's side wall and bottom wall under different gravities are analyzed. Each force and torque acts on side wall and bottom wall can be divided into horizontal and vertical direction, and components on both directions are obtained. The parameters of liquid sloshing equivalent model are calculated. The calculation formula of parameters of equivalent dynamic model is derived by analyzing method. By comparing the simulation results and analytical solutions, the feasibility of the simulation calculation is proved. The simulation method would provide a theoretical basis for dynamic analysis of spacecraft with multiple storage tanks.
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    Thermal Analysis and Strategy of Optical Gondola under a Stratosphere Airship
    ZHAO Kaixuan, PANG Le, DAI Shanliang, ZHANG Xuexun, LUO Haiyan
    2019, 39 (6):  831-837.  doi: 10.11728/cjss2019.06.831
    Abstract ( 409 )   PDF (1373KB) ( 60 )   Save
    Earth limb atmospheric optical observation is one of the important means to study the variation of the characteristics of the middle and upper atmosphere targets. Thermal state of optical remote sensing equipment is very significant to its optical accuracy and SNR control, which directly affects the quality of observation data and the realization of observation task. It is a feasible method to detect mesospheric OH-radicals accurately based on the high-altitude airship platform. A reasonable thermal state is essential to ensure the performance of Spatial Heterodyne Spectrometer (SHS) under a stratosphere airship. In order to meet the thermal control requirements, the thermal environment of the optical gondola and airship is analyzed, and then the thermal mathematical model is established quantitatively. Temperature variations of two typical states, ascent phase and floating phase, are calculated and analyzed successively. The results show that the temperature field and the thermal control measurements can satisfy the temperature control requirement of optical and electronics components. Finally thermal strategy of flight test is analyzed and made correspondingly based on the calculation results of temperature field and heaters. The suggestions for improvement are given, such as increasing initial temperature and total heat capacity, lens protection measures and flexible thermal conduction band for CCD. The analysis method and flight strategy can be used as a useful reference for the design and development of thermal control status of similar equipment.
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    Research on Micro-vibration Detecting Optical Imaging System Verification
    WANG Danyi, JIANG Shanping, ZHANG Pengsong, ZHANG Bolun, YANG Linhua
    2019, 39 (6):  838-846.  doi: 10.11728/cjss2019.06.838
    Abstract ( 405 )   PDF (3242KB) ( 66 )   Save
    According to the system characteristics of high-resolution space camera, the parallel optical tube system is selected as the optical system to simulate the feature target from infinity. The LIGHTTOOLS software is used to simulate the optical path to determine the optimal optical structure. The research is mainly carried out through four experiments, namely camera excitation jitter test, target motion simulation optical axis jitter test, wave front distortion measurement test and defocus measurement test. The optical error of space camera is analyzed and compensated by offline image restoration. The test results show that the 40LP·mm-1 (LP, Line Pair) and 20LP·mm-1 imaged by the camera are clear through the output of the collimator without applying excitation to the camera, which meets the requirements of micro-vibration imaging test. In the micro-vibration imaging test, the collimator has a wavefront aberration of 0.21λ (RMS< λ/4), 1.28λ (PV), and 0.23λ (RMS<λ/4), 1.34λ (PV). The imaging of the system can meet the processing requirements of the recovery software. The collimator optical system can be effectively applied to the micro-vibration imaging detection system and has the ability to successfully verify the micro-vibration imaging detection test.
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    Sequential Imagery Lossless Compression Algorithm for Space Astronomical Observation
    SUN Jianwei, XUE Changbin, ZHENG Tie, ZHANG Zhongwei
    2019, 39 (6):  847-852.  doi: 10.11728/cjss2019.06.847
    Abstract ( 399 )   PDF (794KB) ( 70 )   Save
    In astronomical observation missions, a large number of sequential imagery is obtained. They are produced by fixpoint photography in a period of time, and all have some common features with high resolution and high time-space redundancy. The large volume of such imagery challenges on-board transmission and storage mission. Hence, an algorithm based on inter-frame prediction is proposed in order to reduce the images' bitrates. It includes the intra-frame compression algorithm and an improved inter-frame compression algorithm. The JPEG-LS is adopted to encoding the first image as the intra-frame compression algorithm. Then the other images are compressed by the inter-frame compression algorithm. First, the next image is predicted by its previous image, and then the prediction residuals are transmitted to JPEG-LS predictor for refining. Finally, the refined residuals are encoded by arithmetic encoder. Arithmetic coding does not require encoding each pixel like Huffman coding, and it is closer to the entropy of the image. The experiment result proves that the proposed algorithm promotes the compression performance, and it has lower complexity and less compression time comparing with the traditional JPEG-LS. The proposed algorithm is suitable for real-time onboard compression of astronomical observation sequential imagery.
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