Prepublish have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).
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, Available online  , doi: 10.11728/cjss2022-0035
In this study, based on the Rayleigh lidar echo photon signal of the middle atmosphere, the optimal estimation method is used to retrieve the atmospheric temperature profile. The forward model is constructed by using the Rayleigh lidar equation, and the covariance matrix of the measured signal is determined according to the Poisson counting characteristics of the photodetector. The temperature profile of the atmospheric model is selected as the prior state information, on the basis of which the cost function is determined. Finally, the Levenberg-Marquardt optimization algorithm is used to optimize the cost function. The average kernel matrix is used to evaluate the contribution of real information to the inversion results, and the uncertainty of the inversion results is calculated. The results show that the forward model can correctly describe the real physical process of Rayleigh lidar detecting atmosphere. In the area where the signal-to-noise ratio of the echo photon signal is high, the real information accounts for the main contribution to the inversion results, and the vertical resolution is small. The uncertainty of temperature inversion in the range of height below 90km is between 0K and 10K.
BDSBAS performance evaluation analysis
, Available online  , doi: 10.11728/cjss2022-0039
Satellite-based augmentation is an important means to support civil aviation route operations and terminal area operations. In order to verify whether the BeiDou Satellite-Based Augmentation System (BDSBAS) complies with the International Civil Aviation Organization (ICAO) signal-in-space performance requirements , to evaluate and analyze it. In this paper, the actual broadcast ephemeris, precise ephemeris and BDSBAS enhanced messages are used as experimental data. The performance of BDSBAS was evaluated and analyzed based on six indicators, point, broadcast time and ionospheric delay error. The results show that the GPS satellite orbit error, satellite clock error and space signal ranging error after BDSBAS enhancement are improved compared with those before enhancement; BDSBAS grid ionospheric effective points cover China and surrounding areas; ionospheric delay broadcast interval reaches ICAO Requirements for precise differential positioning; the ionospheric delay has a large error in the range of 0° to 15°N, and the reliability is poor; in the range of 20°N-55°N, the error is small and the reliability is good.
Hardware Acceleration of YOLOv5s Network Model Based on Aerospace-Grade FPGA
, Available online  , doi: 10.11728/cjss2022-0044
With the rapid development of remote sensing engineering technology in our country, the acquisition of remote sensing image data has increased sharply, and the complexity of the image background has also increased. However, the traditional remote sensing image target detection algorithm has low accuracy and weak generalization ability. The accuracy of CNN is gradually difficult to meet the requirements. Aiming at this problem, a processing architecture based on aerospace-grade FPGA for forward inference acceleration of convolutional neural networks is proposed, and the YOLOv5s network model is selected as the benchmark algorithm for the design of the processing architecture. Since the main body of YOLOv5s is composed of a large number of convolutional layers, the center of gravity of the accelerator architecture design is located in the convolutional layer. In the design of the architecture, the parallel expansion of input channels and output channels and the optimization strategy of data pipeline control are used to effectively improve the Real-time processing performance in the inference phase. The experimental results show that when using this processing architecture to accelerate the inference stage of YOLOv5s, the operating frequency of the convolution module can reach 200MHz, its computing performance is as high as 394.4GOP/s, the power consumption of the FPGA is 14.662W, and the average computing efficiency of the DSP calculation matrix It is as high as 96.29%, indicating that using FPGA for hardware acceleration of convolutional neural networks in on-board platforms with limited resources and power consumption has significant advantages.
Automatic Identification of Space hurricane Based on Transfer Learning
, Available online  , doi: 10.11728/cjss2022-0031
Space hurricane is a bright spot-like auroral structure in the polar cap region, which visually characterizes a solar wind energy injection phenomenon comparable to a magnetic storm during the geomagnetic calm period. In this paper, we propose an automatic Space hurricane identification model based on EfficientNetB2 and Transfer Learning, and validate the effectiveness of the model in DMSP/SSUSI observations from 2005-2021 with an accuracy of 97.8%. The results show that the method can be used to automatically identify Space hurricane events from a large amount of satellite-based auroral observation data.
Development of an X-ray Modulation Characterization System for HXI payload onboard ASO-S Mission
, Available online  , doi: 10.11728/cjss2022-0013
The Advanced Space-based Solar Observatory is scheduled to be launched in fall of 2022. The ASO-S carries three payloads to fulfill its science objects. As a key instrument onboard, the Hard X-ray Imager aims at observing solar flares after launch. HXI adopts spatial modulation technique using 91 pairs sub-collimator as Fourier units. However, it is quite hard to calibrate modulating parameters on ground through lack of parallel X-rays in lab. This paper introduces design, fabrication as well as integration of X-ray Modulation Characterization System last year. Application of X-ray beam test was applied for HXI subsequently. Discussion on test results was presented in the end which indicated well performance in orbit.
Response mechanism of tribological properties of WS2 film under different ambient thermal shock
, Available online  , doi: 10.11728/cjss2022-0037
Al: WS2 films were prepared by magnetron sputtering technology. In order to investigate the response mechanism of the tribological properties of Al: WS2 film under different ambient thermal shock, the thermal shock tests of -100~+250℃ in vacuum, nitrogen and oxygen were carried out using the temperature altering vacuum tribometer developed by us, and the structure, composition and tribological properties of Al: WS2 films after thermal shock were mainly studied. It was found that the columnar crystal of Al: WS2 film grows, S content decreases, part of WS2 is oxidized to WO3, and the hardness of film increases after thermal shock. Thermal shock under vacuum and oxygen deteriorates the tribological performance of Al: WS2 films. However, after thermal shock under nitrogen atmosphere, WO3 appears on the surface of Al: WS2 film and was incorporated into the crystal structure, leading to the increase of size of interlayer and the decrease of friction coefficient. Due to the obstruction of a layer of WO3 generated on the surface, the wear life of Al: WS2 film increases. Therefore, thermal shock under nitrogen can improve the tribological performance of Al: WS2 film.
, Available online  , doi: 10.11728/cjss2022-0030
In this paper, the equatorial plasma bubbles (EPBs) of March 30th, 2014 were studied using airglow images of 630 nm emission and observations of VHF radar over Hainan Fuke Station (19.5°N, 109.1°E) from the Meridian Project, digisonde over Hainan Sanya Station (18.4°N, 109.6°E), and data of C/NOFS. In this case, the morphological features and evolution processes in detail were analyzed. The results showed that there were a group of EPBs during the night. Nine EPBs were observed in this case. These EPBs occurred after sunset, lasting after midnight. The lifetime is about eight hours (from ~20: 15 LT to ~ 04: 15 LT). These EPBs moved from west to east during the night. Their longitudinal ranges are more than 1200 km. East-west ranges of EPB group are more than 2900 km. Besides, two EPBs (b5 and b6) showed a merging process. Portion of b6 merged into the b5 and then formed one EPB. When those plasma bubbles were observed by the all-sky imager, corresponding range spread F and plume irregularities also were simultaneously observed by the digisonde and VHF radar, respectively. Meanwhile, observation from C/NOFS also showed plasma depletion. Evolutions of these EPBs were simultaneously observed by optical equipment (all-sky imager) and radio equipment (VHF radar and digisonde) of ground-based measurements, and C/NOFS satellite.
Design and Verification of Scientific Exploration Mode of Zhurong Mars Rover
, Available online  , doi: 10.11728/cjss2022-0022
To obtain as much exploration data as possible with limitations of low communication capability and insufficient energy, Zhurong Mars rover payloads need to improve scientific exploration efficiency. There are two major operating conditions for the payloads, conducting roving exploration when the rover moves and in situ exploration when the rover stops. Serval high-efficiency payload exploration modes were developed for those two conditions. The exploration mode, working with autonomous control based on work mode command set, solved the problem of multiple payloads performing collaborative scientific exploration under resource shortage conditions. The Zhurong Mars rover has successfully completed the scheduled exploration mission. All scientific exploration modes have been verified. The results demonstrate that the exploration modes are suitable and effective, and can meet the requirements of conducting safe, autonomous and efficient scientific exploration.
An Improved HVQ Algorithm for Compression and Rendering of Space Environment Volume Data with Multi-variables
, Available online  , doi: 10.11728/cjss2022-0020
Space environment simulation can produce several correlated variables at the same time. For space environment volume data with multi-correlated variables, based on HVQ-1d method we propose a further improved HVQ method by compositing variable-specific levels to reduce the redundant information among these variables. We further take advantage of progressive rendering based on GPU for real-time interactive visualization. The results of our experiments prove that the method proposed in this paper can pays the least cost of quality at compression and provides satisficed fidelity while ensuring interactive rendering speed in space environment domain. The proposed method can also be applied in other domains.
, Available online  , doi: 10.11728/cjss2022-0027
X-ray occultation is a common astronomical phenomenon. The new technique of atmospheric density retrieval based on X-ray occultation sounding realizes the retrieval of atmospheric density by processing occultation observation data of high-energy X-ray celestial radiation source, which is a new method involving interdisciplinary. This paper briefly introduces the application requirements of X-ray occultation sounding, the new technique of atmospheric density retrieval based on X-ray occultation is analyzed and demonstrated, and mainly introduces the research progress and methods of atmospheric density retrieval based on X-ray occultation, and analyzes and discusses the advantages of atmospheric density retrieval based on X-ray occultation. And the future development direction and application research of X-ray occultation sounding are prospected.
Orbit determination analysis of interplanetary transfer section of Mars probe
, Available online  , doi: 10.11728/cjss2022-0008
Tianwen-1 is the first chinese probe to realize interplanetary flight between Earth and Mars. During the 6.5-month interplanetary transfer flight, it experienced four midway corrections and one deep space maneuver control. In this paper, the dynamic model during deep space exploration is analyzed, and the principle of celestial center conversion during transfer flight is formulated. It is necessary to replace the celestial center with the sun after leaving the earth's influence sphere; The use of planetary ephemeris is analyzed, and it is determined that the use of de436 ephemeris has the least impact on orbit determination; an accuracy evaluation method based on daily iterative orbit determination strategy is developed. Based on the analysis of measured data, it is shown that the orbit determination position error in interplanetary transfer section is better than 2km, and the velocity error is better than 20mm / s (1 σ).
, Available online  , doi: 10.11728/cjss2022-0028
Distribution of the ionospheric irregularities scattering occurrence rate were investigated using data from March, 2018 to November, 2019, which were observed by the SuperDARN Jiamusi and Hokkaido East radars. We statistically compared the irregularities scattering occurrence rate in geomagnetic quiet period (Kp<3) and geomagnetic disturbance period (Kp>3), obtained the variation characteristics of the irregularities scattering occurrence rate depending on magnetic latitude and MLT, and analyzed the characteristics of the occurrence rate enhancement phenomenon in the dusk side and dawn side. The enhancement of the dusk side occurrence rate was widespread in the range of 45°-65ºMLAT, and the occurrence rate in the subauroral region was significantly enhanced during the magnetic disturbed period. The enhancement of the dawn side occurrence rate is mainly distributed in areas below 55ºMLAT, and the enhancement of the geomagnetic disturbance has a weak effect on it except in autumn. The day side occurrence rate in middle magnetic latitude is less affected by geomagnetic disturbance.
Analysis of the main magnetic field order of the global geomagnetic field model based on Bayesian evidencen
, Available online  , doi: 10.11728/cjss2022-0009
This paper uses Bayesian inference to compare the global main magnetic field models, and compares the model order of data preference based on Bayesian evidence. It provides a statistical basis for the order selection of the main magnetic field.Using the Swarm satellite data, Using the Swarm satellite magnetometry data, we estimate the evidence for different orders of the main magnetic field model.The results show that in the order of the main magnetic field from 0 to 20, order N=12 has the global best evidence. Referring to the threshold interval given by Jefrrey's scale, the data preference for order N=12 is significantly better than other orders.the results match the power spectrum analysis of the 14th order spherical harmonics.
Research development and technical difficulties of ultra-LEO spacecraft
, Available online  , doi: 10.11728/cjss2022-0010
Ultra LEO spacecraft has become a hot research field for a wide range of application in military, remote sensing, scientific research, etc. Due to the special space environment of ultra-low orbit, many technical difficulties need to be solved, mainly focusing on atmospheric environment prediction, aerodynamic, aerothermal and so on. This paper introduces the typical mission of ultra LEO spacecraft, the main atmospheric model and inversion method, the aerodynamic design of ultra LEO spacecraft and the stability control method under aerodynamic interference, the aerodynamic thermal protective material and the variable switching technology of thermal insulation and heat dissipation. This review is helpful to promote the key technology research and test demonstration of ultra LEO spacecraft, turning the ultra LEO spacecraft from test mission to space application mission as soon as possible.
Comparative Study between the deriving ionospheric foF2 from nighttime OI 135.6nm emission and ionosonde observations
, Available online  , doi: 10.11728/cjss2022-0018
During the nighttime, the 135.6nm spectral line is excited by the radiation recombination process of F region O+ and e- and the mutual neutralization process of O+ and O- in the ionosphere. There is a strong correlation between the intensity of the spectral line and the maximum electronic density of ionospheric F2 layer (NmF2). Based on the physical model in which the OI 135.6 nm emission is proportional to the square of NmF2, we establish a retrieval algorithm suitable for different longitude and latitude, local time, season and solar activity. In this paper, the critical frequency of ionospheric F2 region (foF2) was retrieved from 135.6nm emission observed by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instrument on board the Defense Meteorological Satellite Program (DMSP), and then the estimated results were compared with the detection results of ground-based ionosonde. As the results show, during the high-solar activity year (2013), the data with relative error less than or equal to 20% accounted for 92.99%, and the average relative error was about 7.18%. During the low-solar activity years (2017), the data with relative error less than or equal to 20% accounted for 80.76%, and the average relative error was about 13.02%. Finally, we analyzed the difference of retrieval accuracy of the algorithm during the high and low solar activity years.
Spectrum Sensing Algorithm for Cognitive Satellite Communication Based on Bi-LSTM and Bayesian Likelihood Ratio Test
, Available online  , doi: 10.11728/cjss2022-0017
With LEO mega satellites constellation coming into operation, the available spectrum resources are more overcrowded. To improve spectrum utilization, cognitive satellite communication technology composed of GEO relay satellites and LEO satellites has become an important choice. The most critical step in the cognitive satellite communication scenario is the spectrum sensing technology used to quickly determine the presence or absence of the primary user. Since most current spectrum sensing algorithms are model-driven, they rely heavily on the assumed statistical model for their detection performance, which makes it more difficult to model and deploy in variable satellite communication scenarios. In this paper, we firstly analyze the signal-to-noise ratio fluctuations during LEO satellite transit, and secondly propose a spectrum sensing algorithm combining bidirectional long short-term memory network and Bayesian likelihood ratio test for this variable channel environment. The algorithm does not require any a priori knowledge of PU signals and can automatically learn features from PU signal data and make decisions. Simulation results show that the proposed algorithm still achieves 83% detection performance at a signal-to-noise ratio of -14 dB and consistently outperforms convolutional neural networks, multi-layer perceptron, and model-driven energy detection-based algorithms.
A Time-Varying Volume Data Transfer Function for Interplanetary Numerical Simulation Data
, Available online  , doi: 10.11728/cjss2022-0011
Understanding the interplanetary propagation of solar storms is the foundation of space environmental forecasting and services. The visualization of numerical model results is an important method to analyze the propagation dynamics process and verify the validity of the model. In order to facilitate the visual analysis of the model results, a transfer function design algorithm for volume rendering of time-varying data(TVTF) is proposed. The algorithm is based on the KNN background subtractor method to extract images including motion regions and motion subsets, and then use frequency-tuned (FT) salient region detection algorithm to detect coronal mass ejection(CME) in motion area images, and according to the CME detection results, a color inverse mapping algorithm is designed to find the boundary threshold between the CME and the background. Finally, the transfer function is adaptively adjusted based on the threshold to realize the fast 3D visualization of CME in the motion region at each time step. The experimental results show that the transfer function can adapt to the numerical model results in static and dynamic backgrounds. Compared with the linear transfer function, the occlusion of the line of sight direction is effectively avoided, the change of relative momentum is intuitively and automatically displayed, and the evolution process of CME in interplanetary space is traced. The extraction of local regions reduces data redundancy, and the process of adaptively adjusting the transfer function by automatically analyzing the data with the help of algorithms avoids the inefficiency of manual adjustment.
Responses of the middle and upper atmospheric wind to geomagnetic activities
, Available online  , doi: 10.117282022-0016

Responses of the middle and upper atmospheric (80-100 km ) wind to geomagnetic activities have been investigated using neutral wind data from 2012 to 2018 years, which were observed by Mohe, Beijing and Wuhan Meteor radars. Daily averaged wind data for geomagnetic quiet condition (Kp ≤ 2) and geomagnetic disturb condition (Kp ≥ 4) were chosen for comparison, and the variation characteristics of wind during geomagnetic disturbances were obtained. The observations show that the influence of geomagnetic activity on zonal wind varied with seasons and latitudes. For zonal wind, the effect of geomagnetic activity at higher latitudes tended to be more westerly wind in the upper mesosphere and more easterly wind in the lower thermosphere, and the differences between disturbed and quiet conditions were on the order of 3 m/s; while for the lower latitudes, it tended to be more easterly wind in the 80-100 km region, and the influence were about 5 m/s. In spring, the three stations had similar tendencies, and had no latitude differences. But the easterly wind in the middle atmosphere became stronger with the decrease of latitude in summer/winter. The effect of geomagnetic activities on the meridional wind had seasonal differences. The influence of geomagnetic activities in spring and winter was stronger than that in summer and autumn. In winter, the effect of geomagnetic activity on the meridional wind in middle and low latitudes was stronger than that in higher latitudes. According to the calculation results, the influence on zonal wind was about 5 m/s to 10 m/s, and on meridional wind was about 3 m/s to 5 m/s. The impact of geomagnetic activities on MLT wind can penetrate down to about 80 km. At this height, the influence on zonal wind was the strongest in spring, reaching 8 m/s, and on meridional wind was the strongest in spring/winter, reaching 5 m/s.

An FPGA-implemented method for real-time multi-dimensional feature extraction of sequence image targets
, Available online  , doi: 10.117282022-0014

The prerequisite of target detection and tracking is to model and represent the target based on multi-dimensional features extracted from the target region. The traditional target feature extraction needs to connect the target region first and then must calculate the target feature, which has still room for improvement in real-time. An advantage of the new method based on the synchronous calculation of pixel-connected domain markers and target features is that the target features can be output when the target region is connected. The process establishes a feature transfer mechanism, creates a marker table, a marker mapping table, and a feature attribute table simultaneously when scanning images, and uses the marker mapping table to associate the marker table and the feature attribute table. The marker merging and feature attribute transfer calculation are performed synchronously at the time of region adjacency, which ensures the real-time target feature extraction. As a result, the method proved to be effective because of an implementation scheme based on an FPGA system design. Simulation test results show that this method has several outstanding features: the time of connected domain markers is close to the theoretical minimum; the storage of images utilizes the circular buffer with low resource consumption; marking and computation are processed in parallel flow to improve detection and tracking efficiency; multi-target features are tested and verified to be accurate, which can effectively support subsequent target tracking detection; and it has theoretical and practical values.