Prepublish

Prepublish have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).
Display Method:
Research on Remote Sensing Satellite Ground Station Antenna Occlusion Forecasting Model and its Application
, Available online  , doi: 10.11728/cjss2023-0134
Abstract(31) PDF 888KB(7)
Abstract:
Based on the practical problems encountered in the operational operation of remote sensing satellite ground stations and operational experience, this paper aims to reduce the impact of obstructions around the antennas of ground stations on the space communication missions of polar orbit satellites such as low-orbit space science satellites and land observation satellites. With the goal of improving the effective communication duration and communication quality between the spacecraft and the ground, the ground station antenna is used as a benchmark for modeling and analyzing the obstructions in the surrounding environment. First establish the occlusion model spatial geometry relationship. The model is chosen to derive the solution for the "minimum elevation angle of the antenna without obstruction". The solid occlusion model equations  and large antenna Occlusion model equations are obtained through model analysis and derivation. Through the model validation, it shows that the model results and the actual situation of the occlusion basically match, and the accuracy of the model calculation results can reach 99.67%. Using the antenna occlusion forecast model as information support, the antenna occlusion forecast is encapsulated into a service, and the computation service of the antenna occlusion forecast and the corresponding mission planning strategy are invoked in the mission planning stage, so as to realize the engineering application of the antenna occlusion forecast model in the operation and management resource scheduling of an earth station. The results of trial operation and application statistics show that the optimization rate of operation management resource scheduling of an earth station has reached 56.07%.Antenna occlusion forecasting can greatly reduce the impact of antenna occlusion on data transmission, telemetry and measurement and control tasks in low-orbit polar-orbit satellite communications, improve the length and quality of effective star-ground communications and the ability of ground station operation and management resource scheduling, reduce the probability of ground station antennas idling, and be of great significance in terms of reducing operational energy consumption, saving national resources and upgrading the indicators for the integration of space communications.
Study on the Method of star Point Extraction for Daytime infrared star Image
, Available online  , doi: 10.11728/cjss2023-0123
Abstract(19) PDF 1134KB(1)
Abstract:
The daytime infrared star image has the characteristics of high background noise, low signal-to-noise ratio and weak target, so it is difficult to accurately extract the star centroid by using the traditional single frame extraction method. Because the stars are weak and small targets, they are extremely sensitive to noise, and the star imaging is mostly random and irregular, so the robustness of extracting the star centroid by single frame is poor. Although the traditional multi-frame superposition method can overcome the problem of poor robustness of star centroid extraction in single frame, for infrared star images with high background noise, the superposition star image cannot significantly improve the signal-to-noise ratio, and the success rate of star extraction is still low. Therefore, this paper proposes a method that uses background prediction method to determine the position of suspected stars, expands the boundary, and then uses the expanded boundary to extract the energy of single frame star image, and superimposes the extracted energy star image to form a high signal-to-noise ratio star image, and finally extracts the star centroid. Experiments show that this method has high success rate of star detection, high accuracy of star centroid extraction and good robustness, which has obvious advantages over traditional methods.
Ionospheric TEC Prediction Based on QPSO-LSTM Model
, Available online  , doi: 10.11728/cjss2023-0143
Abstract(22) PDF 1563KB(7)
Abstract:
For the ionospheric TEC short-term prediction of a single LSTM model, there are difficulties in parameter adjustment and performance optimization, resulting in low prediction accuracy. A combination of quantum particle swarm optimization (QPSO) and LSTM model is used to self-adaptively determine the optimal solution and optimize the parameter configuration of the LSTM model. The prediction accuracy of ionospheric TEC during the quiet period and disturbance period of geomagnetic activity is analyzed. The experimental results show that when the LSTM model optimized by QPSO is used to predict TEC for continuous 5d, the root-mean-square error of a single annual product day can reach the minimum of 0.25TECu, and the relative accuracy can reach 97.02%. The prediction accuracy is better than that of a single LSTM model.
Electron Density Inversion and Magnetic Storm Observation of Yinchuan Vertical Ionosonde
, Available online  , doi: 10.11728/cjss2023-0148
Abstract(23) PDF 1478KB(5)
Abstract:
The local ionospheric electron density is inverted in this paper using the monitoring data from the magnetic fluxgate in Gaoshavo Town and the echo data from the self-developed Yinchuan vertical ionosonde. The ionosonde chooses Bernoulli map sequences as the transmitting code and gathers the echo signals to plot ionograms while simultaneously using the cGAN to extract the echo traces and the corresponding parameters. The vertical electron density profile of the local ionosphere is curved using the modified var-Chapman top model of the Langmuir probe data carried by China Seismo-electromagnetic Satellite (CSES) and the improved IRI inversion model. The results of the total electron content are confirmed with the public data of CDDIS and exhibit a high degree of consistency. Based on these findings, the vertical ionosonde is able to detect anomalous ionosphere changes during the geomagnetic storm that occurred on April 23–24, 2023, and provides the results of the changes in total electron concentration over time. This observational data proved to be accurate and trustworthy for the study of the changes in the electromagnetic environment in the western region of China.
SysML-based fault diagnosis method for space payload systems
, Available online  , doi: 10.11728/cjss2023-0109
Abstract(21) PDF 936KB(4)
Abstract:
Due to the characteristics of high complexity and high reliability requirements of space payload systems, a SysML-based fault diagnosis method is designed. The method incorporates MBSE ideas and proposes a SysML-based modeling process for space payload system and fault analysis, in which the SysML meta-model is extended to meet the needs of fault analysis modeling, thus realizing the description of component relationships and the description of the correspondence between fault representations and directly related components. Next, an overall framework for fault diagnosis is constructed based on the constructed model, and a conversion logic from the SysML model to the FTA analysis is provided, which ultimately enables the acquisition of all possibilities leading to fault representations. Finally, the paper exhibits the process of the methodology in application through a practical example and verifies the effectiveness and usefulness of the methodology.
, Available online  , doi: 10.11728/cjss2023-0138
Abstract(22) PDF 714KB(4)
Abstract:
The "unrecognized and uncertain" is the basic feature of deep space exploration missions, which brings challenges to the applicability of the basic concept of classical reliability. A technology system of dependability for autonomous operation in deep space exploration was proposed based on the principle of "scientific value maximization"-oriented exploration and reliability as the core technology. Firstly, the concept of reliability in the scenario of deep space exploration was analyzed and involved. Secondly, a dependability systematic framework for autonomous operation of deep space exploration and its three-dimensional overall technical architecture of "demand-engineering-cognition" were proposed, which including precise sensing, optimal calculation, accurate decision-making and "quickly, precisely, exactly" execution. Thirdly, the reliability-oriented multi-physics deeply coupled white-box modeling and its "high-fidelity" technology, the complex network fault propagation mechanism and its "high-confidence" technology, the "high-reliability" assurance route for the application of COTS components in deep space exploration, the trinity fusion mechanism of "model + data + knowledge" and its dynamic evolution technology for multi-agent health state management based on multiple fetal sensing phenomena ware studied. Finally, the key technology verification strategies of this technical system and the application verification of its minimum system in the satellite constellation were introduced.
SEE Upset characteristics of BRAM in 28 nm Bulk FPGA by Pulsed Laser Test
, Available online  , doi: 10.11728/cjss2024-0007
Abstract(28) PDF 787KB(3)
Abstract:
In order to research the Single Event Effect characteristics of block RAM in SRAM based FPGA, pulsed laser test were performed on 28 nm bulk Kintex-7 XC7K410T-FFG900 FPGA. The Single-cell upset (SCU) and Multiple-cell (MCU) upset induced by pulsed laser were observed during the test, and the cross section under different laser energy was tested. Besides, we have analyzed the Multi-cell upset patterns of BRAM in FPGA. The result shows that the proportion of Multi-cell upset climbs up with the increasing laser energy, while the proportion of Single-cell upset goes in the opposite way. Two to eleven bits MCU may be induced by one pulsed laser, but without MBU in any logical word. Some SEE mitigation methods were suggested at the end of this paper according the result of SEE test to improve the reliability of SRAM based FPGA in space application.
Deep learning prediction method based on ionospheric parameter similarity features
, Available online  , doi: 10.11728/cjss2023-0110
Abstract(21) PDF 533KB(6)
Abstract:
The ionospheric critical frequency foF2 is one of the important ionospheric parameters, and conducting foF2 parameter prediction has important research significance and application value. This article proposes a deep learning prediction method that integrates the variation characteristics of foF2 parameters, using a bidirectional long short time memory neural network BiLSTM network and a model that combines ionospheric parameter similarity features to achieve 24-hour advance prediction of the ionospheric critical frequency foF2 parameters. The results indicate that the relative error of BiLSTM combined with ionospheric parameter similarity model in predicting foF2 parameters is around 8%~10%. The prediction results of detection stations at different latitudes indicate that as the latitude decreases, the difficulty and error of prediction increase, and the prediction accuracy decreases. The analysis of the prediction results of foF2 parameters during geomagnetic storms shows that the prediction effect during geomagnetic storms will be affected to a certain extent, and the prediction error will increase. During geomagnetic storms, compared to LSTM and BiLSTM models, BiLSTM combined with ionospheric parameter similarity feature models performs better in predicting foF2 parameters.
Research on on-board application of FlexRay bus
, Available online  , doi: 10.11728/cjss2023-0124
Abstract(28) PDF 1246KB(6)
Abstract:
The on-board data bus is the "nerve centre" of satellite integrated electronics. In view of the fact that the existing on-board buses represented by 1553B and CAN bus cannot meet the increasing demand for satellite bus data transmission, this paper carries out the research on the starboard application of the ground-mature high-reliability and high-speed FlexRay bus. Firstly, the technical advantages of FlexRay bus applied to satellite integrated electronics are analysed, and the hardware and software design of FlexRay star-carrying communication node is carried out; taking into account that FlexRay bus is used as an extension or supplement to the traditional CAN bus when it is applied in the orbit, the gateway function of CAN bus and FlexRay bus is designed and implemented, and the sequential order of the bus messages is achieved by adopting the rotational mapping algorithm. The rotational mapping algorithm is used to realise the sequential exchange of bus messages. After the BER test, the data are sent and received continuously, and the data of different bus messages in the network are exchanged normally without frame loss or frame error, and the BER is lower than 10-9. The test result verifies the validity and reliability of the design of the on-board FlexRay bus system.
Study on the active regulation mechanism of laser photothermal effect on thermocapillary convection of double-layer fluid
, Available online  , doi: 10.11728/cjss2023-0036
Abstract(18) PDF 915KB(3)
Abstract:
Active control of thermocapillary convective instability is a frontier scientific issue in the field of microgravity hydrodynamics and heat and mass transfer. In order to achieve effective control of thermocapillary convective instability of double-layer fluid, this paper innovatively proposes to use laser photothermal effect to actively control flow, The regulation mechanism of laser photothermal effect parameters (laser beam position, laser power and spot size) on the instability of double-layer thermocapillary convection is also studied. The calculation results show that the adjustment of laser power and spot size can significantly change the convective vortex structure in the spot area and weaken the vibration amplitude of temperature wave; The adjustment of the laser position can affect the position of the local convection vortex in the liquid layer, and then change the convection intensity on both sides of the laser position, so as to realize the control of the oscillating and unstable flow in the local region; The effective control of thermocapillary convection of double-layer fluid can be realized through the reasonable selection of photothermal effect parameters.
Review of the Development of Space Rodent Experiments
, Available online  , doi: 10.11728/cjss2023-0096
Abstract(54) PDF 1252KB(14)
Abstract:
Human beings have never stopped exploring the unknown universe. Since the twentieth century, human activities in outer space have become more and more frequent, and with the development of manned space engineering, astronauts have stopped in space for longer and longer, and various health problems brought by it need to be solved urgently. To this end, various countries have successively carried out space rodent experiments to study the impact of the space environment on living organisms. This paper investigates the mainstream foreign space rodent culture technologies and devices, and analyzes the space rodent experiments that have been carried out internationally, in order to provide reference for the design of space rodent experimental devices in China.
International Lunar Research Station CommunicationBased on Satellite Double Relay
, Available online  , doi: 10.11728/cjss2023-0129
Abstract(42) PDF 794KB(8)
Abstract:
After the construction of the international lunar research station where astronauts/scientists may reside is completed, maintaining high reliability and seamless communication with China's ground control center will be an important requirement. In the long run, The foreign stations of China’s deep space TT&C system maybe have the following risks: reducing the reliability of China’s deep space TT&C system, and affecting the highly reliable communication between the international lunar research station and the ground control center. Therefore, based on the introduction of the current situation of lunar exploration in China, and drawing on the design, construction, application, and development practices of the TDRSS (in chinese), a concept of satellite double relay communication is proposed. Firstly, coverage simulation analysis under various conditions was conducted from the perspective of geometric visibility; Secondly, research and exploration were conducted from various aspects such as microwave/laser frequency band selection, transmission system, link design, system composition, capture and tracking, overall positioning, and performance comparison with deep space TT&C system. Through connecting the past and the future, innovative ideas, and top-level argumentation, a preliminary exploration on the highly reliable communication of the international lunar research station based on the satellite double relay has been completed. Under the unified control of the ground control center, through the comprehensive utilization of China’s deep space TT&C system and the satellite double relay, the highly reliable and seamless communication between the international lunar research station and the ground control center will have a fully realized technical foundation. In addition, this idea can also provide reference for other spacecraft communication in Earth Moon space and interplanetary exploration, and further promote the integration and innovation of China's ground-based, space-based, and deep space TT&C system.
Research on interfacial flow and thermal stratification of cryogenic liquid nitrogen in variable gravity
, Available online  , doi: 10.11728/cjss2023-0111
Abstract(19) PDF 3268KB(5)
Abstract:
In order to study the effects of g on the flow, phase distribution, temperature distribution, and pressure distribution of liquid nitrogen tank during self-pressurization, the self-pressurization process of liquid nitrogen tank under different g was numerically simulated by the Volume-Of-Fluid (VOF) method. The results show that under the condition of large g, the fluid pressure in the tank increases gradually along the direction of residual gravity, and the temperature of the ullage in the tank increases with the continuous heat leakage of the tank wall, and the gas temperature near the wall is the highest, and the gas temperature near the liquid is the lowest, while the temperature in the liquid bulk zone of the tank changes little with time. With the decrease of g, the liquid in the tank is more likely to climb along the wall of the tank with better infiltration, and the temperature difference of the fluid in the tank is gradually reduced. In the case of a small g, after the fluid flow in the tank is stable, the ullage will be wrapped in the middle of the tank, forming a spherical bubble. The difference of the fluid temperature in the tank gradually increases and then decreases with time. In zero gravity environment, the presence or absence of heat leakage (qw = 0.5 W/m2) on the tank wall has no significant influence on the fluid movement and phase distribution in the tank, and within the initial time interval ∆tf (0 s ≤ ∆tf ≤ 40 s), the influence of the presence or absence of qw on the temperature distribution of the fluid in the tank also is not significant except near the wall of the tank. Numerical simulation results are expected to provide references to further study the on-orbit pressure control technique of cryogenic liquid tanks and space cryogenic fluid management.
Space Radiation-Induced Impacts on Gut Flora, Metabolitesand Multisystem Diseases
, Available online  , doi: 10.11728/cjss2023-0126
Abstract(24) PDF 615KB(8)
Abstract:
Maintaining the homeostasis of gut flora is of great significance to protecting human health. Gut flora plays a key role in regulating body functions, such as digestion, metabolism, immunity, and cognition. These physiological functions often depend on the diversity of gut flora, the stability of the bacterial flora structure, and the balance of the microecology. In the outer space, astronauts face many special environmental factors including the space radiation. Space radiation can cause imbalance of gut flora and changes in metabolites, damaging the intestinal barrier function, and further lead to pathological injury to multiple systems such as the intestine, cardiovascular, brain, and lungs. This article reviews the characteristic changes in gut flora homeostasis and its metabolites under space flight or simulated space radiation, as well as the interaction between gut flora and intestinal damage and other multi-system diseases under radiation effects. It is expected to provide a reference for the further study of the pathological mechanisms upon space radiation and radiation protection measures.
The occurrence and infrared absorption spectra of Martian water
, Available online  , doi: 10.11728/cjss2023-0118
Abstract(39) PDF 2510KB(13)
Abstract:
After nearly half a century of exploration, the researches of Martian water have made important achievements, which provides essential information for understanding the historical information of Martian water and the evolution of the Martian environment, especially arousing the enthusiasm of human beings to search for life on Mars. The study of the occurrence and host minerals of Martian water is of great significance for understanding the composition of Martian surface materials, the evolution of Martian environment and climate, and the livability of life. Infrared spectroscopy is an important method to identify the occurrence of water on the Martian surface and the host minerals. At present, water vapor, water ice and various aqueous substances such as sulfate, clay minerals, hydroxides and hydrated silica have been identified on the Martian surface, indicating that there were several periods of aqueous activities in different water environments in Martian history. In this paper, the occurrence of Martian water and the information of Martian historical environment are summarized, and the infrared spectral characteristics of different water-bearing minerals and the main influencing factors including the type of host minerals, temperature, grain size and mixture are synthetic analyzed. Finally, the changes of infrared spectral absorption characteristics of groups such as H2O and OH are generalized. Regarding the origin and evolution of Martian water and the livability of Mars, China's ongoing exploration of "Tianwen-1" and future "Tianwen-3" are expected to gain breakthrough.
, Available online  , doi: 10.11728/cjss2023-0121
Abstract(33) PDF 465KB(12)
Abstract:
The National Center for Space Weather (NCSW) has been providing space weather forecasts for the next 24h, 48h and 72h since July 1, 2004. In this paper, we use the average error, the average absolute error, the skill score, the median error and the interquartile range of error to verify the forecasts of F107 index and Ap index of NCSW from 2005 to 2022. It was found that the F107 index forecasted by NCSW for the next 24h, 48h, and 72h are usually smaller than the observed F107 index; the Ap index for the next 24h is usually higher than the observed Ap index, while Ap index forecasted for the next 48h and 72h are usually lower than the observed Ap index. The higher the level of solar activity, the greater the forecast error of the F107 index is. However, the maximum forecast error of the Ap index occurs in the declining period of solar activity. In addition, we compared the forecasts of NCSW with the simple numerical models such as the persistence model, 14 days recurrence model, 14 days corrected recurrence model, 27 days recurrence model, and 27 days corrected recurrence model, and found that the forecast performance of NCSW is usually better than that of five simple numerical models. For the F107 index, the forecast performance of NCSW is slightly better than that of the persistence model, and significantly better than that of the four recurrence models. However, when the solar activity level is high, the persistence model's performance of the F107 index for the next 72h is better than that of NCSW. For the Ap index, in most cases, the performance of NCSW is significantly better than that of numerical models. However, when geomagnetic disturbances are severe, the Ap index forecasted by the 27 days recurrence model is more accurate than that forecasted by NCSW.
Application of deep clustering algorithm in target echo classification of SuperDARN radar
, Available online  , doi: 10.11728/cjss2023-0136
Abstract(45) PDF 911KB(7)
Abstract:
SuperDARN radar target echoes usually contain echoes of various types of scattering, such as ionospheric irregularities, ground/sea scatter echoes, polar mesosphere summer echoes, and meteor trail echoes. The ionospheric convection map made by using the ionospheric echoes collected by SuperDARN is of great significance for space weather research. The scattered ionospheric echoes received by SuperDARN are often mixed with the scattered echoes from the ground or the sea, resulting in inaccurate ionospheric convection maps. Therefore, cluster analysis of SuperDARN target echoes is of great significance. In this paper, the graph embedding deep clustering algorithm based on autoencoder network is applied to SuperDARN target echo data for the first time, and SuperDARN echo data is effectively classified. In addition, the model is compared with traditional algorithms and machine learning clustering algorithms. The application of this model to sample data shows that the deep clustering algorithm can capture the deep structure features of echo data and improve the precision of echo clustering.
Research and prospect of in-situ construction materials on Mars
, Available online  , doi: 10.11728/cjss2023-0137
Abstract(34) PDF 1711KB(10)
Abstract:
Martian regolith is an important in-situ natural resource for building habitats and infrastructure on Mars. Based on the extreme environment of Mars and the special properties of pyrosol, the physical and mechanical properties of in-situ construction materials on Mars are reviewed in detail in this paper. The research progress in two aspects of pyrosol concrete materials, pyrosol melting and sintered in-situ curing materials is emphasized. The problems and limitations of these materials in Mars construction are pointed out, and the development direction of in-situ construction materials on Mars is prospected, in order to provide reference for the realization of in-situ construction on Mars.
Comparison between temperature data detected by ICON/MIGHTI and TIMED/SABER
, Available online  , doi: 10.11728/cjss2023-0094
Abstract(55) PDF 760KB(17)
Abstract:
The ICON satellite provides data for environmental characterization, modeling, and forecasting in near space. In this paper, the ICON/MIGHTI and TIMED/SABER temperature datasets were compared and analyzed in the range of 90~105 km, and the mean temperature deviation and root-mean-square error of both were calculated. The distribution of monthly mean temperature deviation with altitude and latitude in different months were also analyzed to provide a reference basis for MIGHTI and SABER temperature sounding data in modeling and forecasting applications of the near-space atmosphere. The results showed that ICON/MIGHTI and SABER temperature-sounding data can be used as references for modeling and forecasting applications. The results also showed that the ICON/MIGHTI and TIMED/SABER vertical profile detections agreed. The global mean temperature deviations with altitude were positive at 90~93 km, with a maximum deviation of approximately 2.5 K and negative at 93~105 km, with a maximum deviation of approximately 10 K. The deviation was usually higher during the day than at night. The mean temperature deviation varied significantly with season and latitude and had the largest mean deviation range and the largest root-mean-square error of temperature in summer.
Comprison of FY3D/GNOS atmospheric occultation detection temperature with TIMED/SABER detection temperature and NRLMSISE00 model temperature
, Available online  , doi: 10.11728/cjss2023-0072
Abstract(34) PDF 775KB(12)
Abstract:
The accurate detection of atmospheric temperature data is of great significance for the study of the structural characteristics and dynamic processes of the upper atmosphere. Launched in November 2017, China's Fengyun-3D satellite Discovery Explorer(GNOS) conducts a global exploration of atmospheric temperatures. The purpose of this study is to evaluate the atmospheric temperature data products of the FY3D satellite. We used the FY3D occultation observation data from January 2019 to December 2021, and the TIMED/SABER detection data and NRLMSISE00 atmospheric model data to compare and study the atmospheric temperature data in the range of 12~100 km. The temperature deviation of SABER-FY3D(TSABER-TFY3D) and NRLMSISE00-FY3D temperature deviation (TNRLMSISE00-TFY3D) and their distribution with latitude, season and northern and southern hemispheres were analyzed. The results show that the three temperature data are generally consistent with the height change trend, SABER-FY3D temperature deviation is positive deviation in the altitude range of 12~30 km, close to 0 K at about 30 km, and the negative deviation above 30 km is mainly negative, and with the increase of altitude, the negative deviation is increasing overall. NRLMSISE00-FY3D temperature deviation is positive deviation in the stratosphere and negative deviation in the mesosphere and low thermosphere. Both temperature deviations have obvious characteristics with latitude and season. Below 60 km, the temperature deviation of SABER-FY3D is smaller in the low latitude region, larger in the high latitude area, smaller in summer and larger in winter. NRLMSISE00-FY3D temperature deviation is just the opposite, smaller in high latitudes, larger in low latitudes, smaller in winter, and larger in summer. The zero deviation line of the average monthly temperature deviation of the two types is located at a higher height in spring and summer and a lower autumn and winter in both northern and southern hemispheres. In the winter altitude area of 40~60 km, the negative deviation of SABER-FY3D average temperature in the northern hemisphere is more obvious than that in the southern hemisphere.
Study on evolution mechanism of PCM liquid-bridge phase transition
, Available online  , doi: 10.11728/cjss2023-0105
Abstract(55) PDF 1158KB(7)
Abstract:
In order to reveal the flow characteristics and phase transition evolution law of PCM liquid bridge phase transition process under microgravity conditions, the evolution process of solid-liquid interface during PCM liquid bridge phase transition under different working conditions was systematically studied based on the axisymmetric PCM liquid bridge mathematical model. the effects of different high diameter ratios and different temperature differences on the shape of the liquid bridge, the evolution law of solid-liquid interface, the phase transition speed and thermocapillary flow were investigated. The results show that the thermal capillary flow is more intense under the action of large temperature difference, the phase change speed of the phase change material at the outer wall will be faster, and the angle between the phase change interface at the outer wall and the wall surface will be smaller. A large high diameter ratio has the same effect, but also produces more eddy currents, making the final steady-state process more oscillating.
Modeling next 3-day Kp index forecasting with neural networks and exploring the application of explainable AI
, Available online  , doi: 10.11728/cjss2023-0107
Abstract(88) PDF 731KB(19)
Abstract:
    The current operational needs of space weather forecasting strongly require accurate predictions of the future 3-day Kp index. Such forecasts involve a multitude of predictors, including physical parameters observed at the Earth-Sun L1 point and historical characteristics of the Kp index. Therefore, previous research primarily relied on statistical or empirical methods for prediction. However, the complex coupling of multiple parameters during geomagnetic storm events has made it challenging to quantify the contributions of various predictors to Kp index forecasting over a 3-day timescale, hindering further improvements in forecast accuracy. This study builds a 3-day Kp index forecasting model based on neural network modeling and utilizes explainable AI algorithm, specifically the integrated gradient algorithm, to quantify the contributions of individual predictor. The research results indicate that the southward interplanetary magnetic field contributes significantly to Kp index prediction, accounting for 37.15% of all factors, making it the primary contributor. Following this, solar wind speed contributes 15.73%, underscoring the model's ability to capture parameters aligned with physical characteristics as the primary predictive factors during training. The contribution of historical characteristics of Kp index (recurrence characteristics) gradually increases with the forecasting horizon and reaches 68.06% at a lead time of 3 days. This substantiates the strong predictive capabilities of the AI model in forecasting geomagnetic storm events induced by high-speed solar wind streams originating from coronal holes. Furthermore, this study conducts contribution analysis on two significant geomagnetic storm events that occurred in 2015 and 2017. It reveals that the predominant predictors contributing to each event differ. This underscores the model's capability to accurately capture the complex coupling of multiple parameters in geomagnetic storm forecasting. In conclusion, this research demonstrates that employing explainable AI algorithms can help quantify the contributions of various predictive factors to Kp index forecasting to some extent. This has the potential to enhance further research and improvements in 3-day Kp index AI forecasting models.
Numerical validation of lunar subsurface dielectric property estimation based on full waveform inversion
, Available online  , doi: 10.11728/cjss2023-0115
Abstract(81) PDF 1190KB(8)
Abstract:
Dielectric property is an important parameter that determines the propagation speed of radar wave in materials, which is widely used in stratigraphic division, regolith thickness inversion, radar model construction and water-ice detection. However, continuous impacts may cover the traces of important geological activities and hinder the exploration of lunar geological. The subsurface radar diagram with fine vertical resolution provided by the Chang’E-4 Lunar Penetrating Radar (CE-4 LPR) can deepen our understanding of the dielectric property of lunar subsurface materials. Full waveform inversion (FWI) method can fully utilize the kinematic and dynamic information of radar wave field and invert the dielectric property by constructing an initial dielectric model and continuously updating this model with comparison of the observed radar data. By comparing the simulation results of homogeneous dielectric model and stochastic equivalent media model to the LPR diagram, we selected the stochastic equivalent media model as the real model to simulate the lunar subsurface dielectric profile and valid the dielectric accuracy inversed by FWI method. Our results reported that most error are within 0.2, suggesting FWI method can capture fine-scale dielectric fluctuation and provide 2-D dielectric profile, supporting the regolith thickness estimation and subsurface temperature model.
Remanence model estimation method of geomagnetic navigation carrier based on recursive least square method
, Available online  , doi: 10.11728/cjss2023-0002
Abstract(87) PDF 2617KB(44)
Abstract:
Geomagnetic navigation is a method to realize navigation by measuring the vector magnetic field around the earth. It is a passive navigation, which has the advantages of strong anti-interference ability and no cumulative error. One of the difficulties in the application of geomagnetic navigation on moving platform is the influence of platform remanence on geomagnetic measurement, which seriously pollutes the measurement of magnetometer and becomes a key technology in the transformation of geomagnetic navigation to application. In order to realize effective measurement and estimation of remanence of moving platform, a method of differential measurement and estimation of remanence of moving platform based on recursive least square method is proposed. Firstly, based on the analysis of magnetic dipole theory, the method deduces that the value of carrier interference magnetic field is only related to the distance between measuring point and magnetic dipole and the equivalent magnetic moment of magnetic dipole. Based on the above conclusions and the magnetic field distribution characteristics of the magnetic dipole, a remanence difference estimation model of the moving platform based on the built-in magnetometer array is derived, and the difference estimation model is solved by recursive least square method. Finally, a large number of simulation experiments show that platform remanence can be measured and estimated by the built-in array magnetometer, which proves the effectiveness of the proposed method.
Distribution and Characteristics of Martian precipitating H-ENA
, Available online  , doi: 10.11728/cjss2023-0044
Abstract(67) PDF 863KB(13)
Abstract:
Energetic Neutral Atom (ENA) is generated by charge exchange between energetic ions and background neutrals. As Martian exosphere extends far above the bow shock, hydrogen ENA (H-ENA) produced by solar wind protons may enter the lower atmosphere directly, depositing mass and energy in the atmosphere. Based on the single-fluid multispecies MHD model and exosphere model, this paper calculates the spatial distribution of the precipitating H-ENA flux at the height of 200km on Mars, evaluates the particle and energy deposition rate of the precipitating H-ENA under different solar wind conditions, analyzes their controlling factors. The results show that the solar wind H-ENA generated upstream of the bow shock is less affected by the crustal fields, and shows a cos(SZA) distribution. As a major mass and energy source, the precipitating H-ENA accounts for 59% and 81% of the total precipitating ENAs. Magnetosheath H-ENAs generated in the magnetosheath is greatly affected by the crustal fields, and their precipitating flux decreases significantly above the strongest magnetic anomalies. The precipitating H-ENA is proportional to the upstream solar wind flux, 2.1~3.5% of which are estimated to be converted into the solar wind H-ENAs.
A Lightweight Automatic Detection Model for Lightning Whistle Waves Based on improved YOLOv5
, Available online  , doi: 10.11728/cjss2023-0067
Abstract(78) PDF 2449KB(12)
Abstract:
Lightning whistler wave is a strong electromagnetic whistler wave caused by atmospheric lightning thunderstorm. It shows typical characteristics of electromagnetic spectrum in electromagnetic field observation recorded by LEO electromagnetic satellite, and has important value. The existing reported lightning whistle wave detection models have problems such as high miss detection rate, high computational complexity, and slow deployment on satellite platforms. This project proposes an improved YOLOv5 detection algorithm YOLOv5 Upgraded. To address this issue, the study proposes an improved YOLOv5 detection algorithm called YOLOv5-Upgraded.The model takes into account the vector angle between the predicted edge and the real edge, we propose replacing the CIoU loss function with SIoU to improve the speed of locating the real edge. Additionally, to prevent issues such as gradient disappearance, gradient explosion, and neuron necrosis during network training, we suggest replacing the SiLU activation function with the Mish activation function. The Mish activation function offers better gradient flow, and its smooth function curve allows information to easily penetrate the network.The CA attention mechanism is inserted into the backbone network to help the model identify the Lightning whistler waves more accurately and greatly reduce the missed detection rate. The study is based on the VLF-band data of CSES satellite induction magnetometer (SCM) with 2.4 seconds time window to intercept data, and 1126 time-frequency map data sets are obtained by band-pass filtering and short-time Fourier transform, and then expanded to 7882 images by brightening, darkening, adding pretzel noise, Gaussian noise and other image enhancement operations, of which 7091 are used as training set and 791 are used as test set. Experimentally, the average mean accuracy (mAP) of the improved YOLOv5-based model is 99.09% and the Recall is 96.20%, which are improved by 2.75% and 5.07% compared with the plain YOLOv5s, and 5.89% and 9.62% compared with the time-frequency map-based YOLOv3 model. The size of LSTM based on the speech processing technology Lightning whistler waves recognition model is 82.89MB, while the YOLOv5-Upgraded model is only 13.78MB, saving about 83.38% of memory resources. It is shown that the model greatly reduces the leakage problem of Lightning whistler waves, achieves better results in the test set as well as in the real orbit, and its lightweight features are easy to deploy to satellite devices, which greatly improves the possibility of satellite recognition.
, Available online  , doi: 10.11728/cjss2023-0057
Abstract(39) PDF 1211KB(7)
Abstract:
The system design of millimeter wave atmospheric ozone radiometer
, Available online  , doi: 10.11728/cjss2023-0053
Abstract(44) PDF 974KB(3)
Abstract:
Stratospheric ozone concentration has an important impact on global climate change and ecological environment. Hyperspectral millimeter wave radiometer with spectral analysis capability is a passive microwave remote sensor used to detect atmospheric trace gases. It can effectively detect the vertical profile of atmospheric ozone and has very important application value in the field of space earth science. In this paper, a new hyperspectral millimeter wave ozone radiometer system for detecting stratospheric ozone absorption lines is developed. The system structure includes RF receiver and digital back-end spectrum analyzer. The RF receiver part uses a superheterodyne structure to obtain a 142.175GHz ± 100MHz bandwidth signal. The digital back-end spectrum analysis part uses a high-performance analog-to-digital converter to sample the input analog signal at 500Msps, 14bit quantization, and the input signal 3dB bandwidth is 200MHz. The signal power spectrum is obtained by high-performance field programmable gate array(FPGA), and the number of detection channels is 16384, and the spectral resolution is 12.2kHz. This paper introduces the design scheme, device selection and test method of the key modules of the radiometer system. By conducting atmospheric detection experiments and comparing the experimental results with the simulation results of atmospheric radiative transfer simulation software (ARTS), the correctness of the system design is verified. It meets the application requirements of stratospheric ozone concentration monitoring, early warning and climate change research.
QX-1 GNOSMRadio Occultation Data Performance Analysis
, Available online  , doi: 10.11728/cjss2023-0071
Abstract(78) PDF 1057KB(24)
Abstract:
　　QX-1 GNOS M is a commercial global navigation satellite occultation sounder that is the first to achieve miniaturization and compatibility with the BeiDou, GPS, and Galileo systems in orbit. It was launched into orbit on October 14, 2021 at 18: 51, aboard the QX-1 satellite, and has collected a large amount of occultation data. The composition of QX-1 GNOS M payload is introduced, and the global distribution of the occultation events on August 17, 2022 is statistically analyzed. Based on the QX-1 GNOS M datasets from August 17 to September 3, 2022, the detection penetration depth of the occultation profiles has been inspected.
　　Comparing with the NCEP reanalysis data, the QX-1 GNOS M occultation refractivity accuracy has been analyzed, which verified the reliability and consistency of Galileo radio occultation data. The preliminary results indicate that the compatibility with three systems increases the number of occultation events by about 1.5 times compared to GPS alone. This study further demonstrated the consistency of the radio occultation product accuracy of different GNSS systems. The successful operation of the QX-1 GNOS M micro-nano occultation satellite opens the prelude to China's micro-nano occultation constellation network exploration.
A Statistical Analysis of Distributions of Electron Energy Spectra in the Earth's Radiation Belts based on Van Allen Probes Observations
, Available online  , doi: 10.11728/cjss2023-0070
Abstract(115) PDF 2927KB(31)
Abstract:
The characteristics of energy spectra distributions of radiation belt electrons can help reveal the dominant physical mechanism behind the dynamics of the radiation belt. In this study, the temporal and spatial distribution characteristics of energy spectra of energetic electrons are statistically analyzed using the measurements from Van Allen probes during 2014-2018. The results show that most of the electron spectra in the radiation belt can be classified into three types: exponential, power-law and reversed spectra. The exponential spectra dominate in the outer radiation belt outside the plasmapause. The power-law spectra usually occur at higher L values and move to lower L values during geomagnetic storms. During quiet geomagnetic activity periods, the power-law energy spectra stay at the high L with longer time and higher proportion. The reversed energy spectra dominate at L>2.5 inside the plasmasphere. As the increase of plasmapause locations, more reversed energy spectra occur while the proportion of the exponential energy spectra decreases. During long-term quiet periods, electron fluxes near the peak of the reversed energy spectra (around 2 MeV) are relatively low to form obvious reversed spectral. The results also show that the peak location of reversed energy spectra is ~2 L inside the plasmapause while the peak location of exponential energy spectra is ~1.5 L outside the plasmapause. Appearances of power-law energy spectra are related to substorm injections of electrons. Stronger magnetic storms produce wider L ranges where reversed energy spectra are replaced by exponential spectra. During quiet times, exponential energy spectra inside the plasmapause are replaced by reversed energy spectra due to pitch angle scattering produced by plasmaspheric hiss waves.
, Available online  , doi: 10.11728/cjss2023-0040
Abstract(210) PDF 989KB(45)
Abstract:
The F10.7 index is an important indicator of solar activity. Accurate predictions of the F10.7 index can help prevent and mitigate the effects of solar activity on areas such as radio communications, navigation and satellite communications. Based on the properties of the F10.7 radio flux, the prediction model of F10.7 based on BiLSTM-Attention is proposed for the first time by incorporating an Attention mechanism on the Bidirectional Long Short-Term Memory Network (BiLSTM). The mean absolute error (MAE) on the Canadian DRAO dataset is 5.38, the mean absolute percentage error (MAPE) is controlled to within 5% and the correlation coefficient (R) reaches 0.987. It has superior predictive performance compared to other RNN models. A Conversion Average Calibration (CAC) method is proposed for the first time to preprocess the F10.7 data set observed by the Langfang L&S telescope in China. The processed data has high correlation with the DRAO dataset. Based on this dataset the forecasting effectiveness of the RNN series models is compared and analysed. The experimental results show that both BiLSTM-Attention and BiLSTM models have significant advantages in predicting the F10.7 index and show excellent predictive performance and good stability.
Integratedthermal control system for space platform and fractionated payload
, Available online  , doi: 10.11728/cjss2023-0041
Abstract(118) PDF 1436KB(16)
Abstract:
Combined spacecrafts which can implement more complicated targets through fractionated payload or part of the spacecraft from the space platform have been in urgent need with the development of space exploration. Space platform provides carriage service for the fractionated payload or part of the spacecraft before separation. The paper proposed an integrated thermal control system for the space platform and fractionated payload, Thermal simulation proved the rationality and effectiveness of the system, which can be as a reference of such cases.
Research on Ground Simulation Method of Heat Transfer Characteristics for Space High-Temperature Material Experimental Furnace Based on Data-Driven Approach
, Available online  , doi: 10.11728/cjss2023-0023
Abstract(103) PDF 1284KB(17)
Abstract:
The temperature stability during the crystal growth process has a significant impact on the morphology and structure of the crystal. In order to improve the quality of crystals, it is necessary to ensure the stability of temperature throughout the crystal growth process. Currently, in China, PID controllers are used to control the crystal growth temperature in space high-temperature material science experimental furnaces. Due to the limited and scarce opportunities for space experiments, the tuning of control parameters needs to be completed on the ground. However, due to the difference in heat transfer between the ground and space environments, there are differences in the heat transfer characteristics of the furnace, and its transfer functions are also different. If the control parameters tuned on the ground are directly applied to space conditions, it will result in a worse temperature control effect. To address this, this paper proposes a data-driven depressurization method that approximates and simulates the heat transfer characteristics of the furnace under microgravity environments on the ground, and provides the pressure values for ground adaptation conditions. This overcomes the problem of the traditional depressurization method being difficult to determine the pressure value for ground adaptation conditions due to lack of prior knowledge.

Journal Introduction

ISSN 0254-6124       CN 11-1783/V

Copyright © Editorial Office of Chinese Journal of Space Science.  京ICP备08100722号

Supported by: Beijing Renhe Information Technology Co., Ltd.