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Improving the spaceborne GNSS-R altimetric precision based on the novel multilayer feedforward neural network weighted joint prediction model

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Defence Technology（防务技术） 2024年第2期32卷 271-284页

作者： Yiwen Zhang Wei Zheng Zongqiang Liu Qian Xuesen Laboratory of space Technology China Academy of Space TechnologyBeijing 100094China China academy of Aerospace Science and Innovation Beijing 100176China State Key Laboratory of space-Ground Integrated information Technology Beijing Institute of Satellite Information EngineeringBeijing 100194China

Global navigation satellite system-reflection(GNSS-R)sea surface altimetry based on satellite constellation platforms has become a new research direction and inevitable trend,which can meet the altimetric precision at the global scale required for underwater *** present,there are still research gaps for GNSS-R altimetry under this mode,and its altimetric capability cannot be specifically ***,GNSS-R satellite constellations that meet the global altimetry needs to be ***,the matching precision prediction model needs to be established to quantitatively predict the GNSS-R constellation altimetric ***,the GNSS-R constellations altimetric precision under different configuration parameters is calculated,and the mechanism of the influence of orbital altitude,orbital inclination,number of satellites and simulation period on the precision is analyzed,and a new multilayer feedforward neural network weighted joint prediction model is ***,the fit of the prediction model is verified and the performance capability of the model is tested by calculating the R2 value of the model as 0.9972 and the root mean square error(RMSE)as 0.0022,which indicates that the prediction capability of the model is ***,using the novel multilayer feedforward neural network weighted joint prediction model,and considering the research results and realistic costs,it is proposed that when the constellation is set to an orbital altitude of 500 km,orbital inclination of 75and the number of satellites is 6,the altimetry precision can reach 0.0732 m within one year simulation period,which can meet the requirements of underwater navigation precision,and thus can provide a reference basis for subsequent research on spaceborne GNSS-R sea surface altimetry.

关键词： GNSS-R satellite constellations Sea surface altimetric precision Underwater navigation Multilayer feedforward neural network

Large-scale spatial data visualization method based on augmented reality

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虚拟现实与智能硬件（中英文） 2024年第2期6卷 132-147页

作者： Xiaoning QIAO Wenming XIE Xiaodong PENG Guangyun LI Dalin LI Yingyi GUO Jingyi REN Key Laboratory of Electronics and information Technology for space systems National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese academy of Sciences Beijing 100049China Ordnance Science and Research academy of China Beijing 100089China

Background A task assigned to space exploration satellites involves detecting the physical environment within a certain ***,space detection data are complex and *** data are not conducive for researchers'visual perceptions of the evolution and interaction of events in the space *** A time-series dynamic data sampling method for large-scale space was proposed for sample detection data in space and time,and the corresponding relationships between data location features and other attribute features were established.A tone-mapping method based on statistical histogram equalization was proposed and applied to the final attribute feature *** visualization process is optimized for rendering by merging materials,reducing the number of patches,and performing other *** The results of sampling,feature extraction,and uniform visualization of the detection data of complex types,long duration spans,and uneven spatial distributions were *** real-time visualization of large-scale spatial structures using augmented reality devices,particularly low-performance devices,was also *** The proposed visualization system can reconstruct the three-dimensional structure of a large-scale space,express the structure and changes in the spatial environment using augmented reality,and assist in intuitively discovering spatial environmental events and evolutionary rules.

关键词： Large-scale spatial data analysis Visual analysis technology Augmented reality 3D reconstruction space environment

A Numerical Calculation Algorithm of the Inclination Function Based on the Representation of SO(3) Group

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 137-148页

作者： Yu-xiao Wei Wen-lin Tang Department of Geophysics School of Geology Engineering and GeomaticsChang’An UniversityXi’an710064China Key Laboratory of Electronics and information Technology for space systems National Space Science CenterChinese Academy of SciencesBeijing100190China

In the determination of the Earth gravity field in satellite geodesy, the inclination functions represent the projection of data observed along the orbital plane of a satellite orbit into the sphere in the terrestial reference frame. The inclination functions in this work is studied from a group theoretical perspective. The inclination functions are proved to generate a representation of the SO(3) group. An orthogonal relation of the inclination functions is derived and some recurrence relations for the inclination functions are given, based on which an algorithm to calculate the inclination functions is proposed.

关键词： SO(3)group inclination function satellite geodesy representation of SO(3)

Analysis of the joint detection capability of the SMILE satellite and EISCAT-3D radar

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Earth and Planetary Physics 2024年第1期8卷 299-306页

作者： JiaoJiao Zhang TianRan Sun XiZheng Yu DaLin Li Hang Li JiaQi Guo ZongHua Ding Tao Chen Jian Wu Chi Wang State Key Laboratory of space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Key Laboratory of Solar Activity and space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese academy of Sciences Beijing 101408China Key Laboratory of Electronics and information Technology for space systems Chinese Academy of SciencesBeijing 100190China China Research Institute of Radio-wave Propagation Qingdao 266075China

The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)satellite is a small magnetosphere–ionosphere link explorer developed cooperatively between China and *** pioneers the use of X-ray imaging technology to perform large-scale imaging of the Earth’s magnetosheath and polar cusp *** uses a high-precision ultraviolet imager to image the overall configuration of the aurora and monitor changes in the source of solar wind in real time,using in situ detection instruments to improve human understanding of the relationship between solar activity and changes in the Earth’s magnetic *** SMILE satellite is scheduled to launch in *** European Incoherent Scatter Sciences Association(EISCAT)-3D radar is a new generation of European incoherent scatter radar constructed by EISCAT and is the most advanced ground-based ionospheric experimental device in the high-latitude polar *** has multibeam and multidirectional quasi-real-time three-dimensional(3D)imaging capabilities,continuous monitoring and operation capabilities,and multiple-baseline interferometry *** detection by the SMILE satellite and the EISCAT-3D radar is of great significance for revealing the coupling process of the solar wind–magnetosphere–***,we performed an analysis of the joint detection capability of the SMILE satellite and EISCAT-3D,analyzed the period during which the two can perform joint detection,and defined the key scientific problems that can be solved by joint *** addition,we developed Web-based software to search for and visualize the joint detection period of the SMILE satellite and EISCAT-3D radar,which lays the foundation for subsequent joint detection experiments and scientific research.

关键词： Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)satellite European Incoherent Scatter Sciences Association(EISCAT)-3D radar joint detection

Orthogonal waveform design with fractional programming on the ambiguity suppression of SAR systems

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Science China(information Sciences) 2024年第9期67卷 263-279页

作者： Yunkai DENG Yongwei ZHANG Zhimin ZHANG Wei WANG Heng ZHANG Department of space Microwave Remote Sensing System Aerospace Information Research InstituteChinese Academy of Sciences

Waveform diversity(WD) represents a dynamic and transformative technology widely used in radar systems to enhance sensitivity and discrimination capabilities. Recently, WD techniques have been extensively explored for their potential ambiguity suppression within synthetic aperture radar(SAR) *** these, the alternate transmitting mode combined with orthogonal waveforms emerges as a particularly promising solution. This study focuses on optimizing the power spectrum density(PSD) of signals to design and generate an orthogonal waveform pair that achieves both a low cross-correlation-to-autocorrelation ratio(CAR) and satisfactory imaging performance. Initially, we construct a fractional programming model with convex constraints to minimize the CAR. To address this challenge, we introduce an iterative optimization procedure for the PSD variable, which sequentially reduces the CAR. Each optimization step can be efficiently solved using a quadratically constrained quadratic program, ensuring that the resulting computational complexity remains low. Building on the optimized PSD, we established a parametric piecewise linear model to generate an orthogonal waveform pair. This model not only maintains a low CAR but achieves satisfactory imaging performance in real-time applications. Consequently, this orthogonal waveform pair effectively suppresses range ambiguity in SAR systems. Finally, we demonstrated the practicability and effectiveness of the proposed orthogonal waveforms through detailed simulation experiments, specifically targeting ambiguity suppression in conventional quad-polarization SAR systems.

关键词： synthetic aperture radar (SAR) waveform diversity (WD) ambiguity suppression orthogonal waveform fractional programming power spectrum density (PSD)

System design and validation of Queqiao-2 lunar relay communication satellite

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中国空间科学技术(中英文) 2024年第05期 23-39页

作者： ZHANG Lihua XIONG Liang SUN Ji CHEN Luojing XIAO Chuan ZHOU Wenyan WANG Yong LIU Wangwang GUAN Yifeng CHEN Tao YU Xiaochuan XU Jin CHEN Guohui CAO Xiaoping DFH Satellite Co. Ltd. Beijing Institute of spacecraft System Engineering Beijing Institute of Control Engineering academy of space information systems

In order to provide relay communication supports for future Chinese lunar exploration program, Queqiao-2 relay communication satellite was ***-2 can perform scientific observations with three kinds of scientific instruments on *** system design of Queqiao-2,including mission orbit and transfer orbit design, configuration and layout design, housekeeping and information flow design, power supply and distribution design, GNC and propulsion system design, communication links design, etc.,was accomplished through comprehensive tradeoff and evaluation on technical maturity, availability, schedule, cost, and so *** a view to reducing development risk, both the platform and relay communication payloads were developed based on significant heritage from previous Queqiao relay satellite and other relevant ***-2 features flexible system architecture to support multiple frequencies, modulations, data rates and software reconfigurations to meet new user *** to a successful launch on March 20,2024,by means of 5 orbit maneuvers, Queqiao-2 was inserted into a highly elliptical frozen mission orbit around the moon with a 24h period on *** on-orbit tests and calibrations, Queqiao-2 has possessed the capacity to provide reliable relay communication services to multiple lunar exploration missions, as well as the capacity to perform scientific *** the support of Queqiao-2,Chang′e-6 achieved its ambitious mission goal to collect and return samples from the moon′s mysterious far *** the meanwhile, Queqiao-2 has also paved the way for the following Chinese lunar exploration missions including Chang′e-7 and Chang′*** design life time of Queqiao-2 is more than 8 *** from flexibility and extensibility of relay communication system design, it is convenient to provide relay communication services for future lunar exploration missions of both China and other *** addition, innovative

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Using restored two-dimensional X-ray images to reconstruct the three-dimensional magnetopause

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Earth and Planetary Physics 2024年第1期8卷 133-154页

作者： RongCong Wang JiaQi Wang DaLin Li TianRan Sun XiaoDong Peng YiHong Guo National space Science Center Chinese Academy of SciencesBeijing 100190China University of Chinese academy of Sciences Beijing100049China Aerospace information Research Institute Chinese Academy of SciencesBeijing 100094China

Astronomical imaging technologies are basic tools for the exploration of the universe,providing basic data for the research of astronomy and space *** Soft X-ray Imager(SXI)carried by the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)aims to capture two-dimensional(2-D)images of the Earth’s magnetosheath by using soft X-ray ***,the observed 2-D images are affected by many noise factors,destroying the contained information,which is not conducive to the subsequent reconstruction of the three-dimensional(3-D)structure of the *** analysis of SXI-simulated observation images shows that such damage cannot be evaluated with traditional restoration *** makes it difficult to establish the mapping relationship between SXIsimulated observation images and target images by using mathematical *** propose an image restoration algorithm for SXIsimulated observation images that can recover large-scale structure information on the *** idea is to train a patch estimator by selecting noise–clean patch pairs with the same distribution through the Classification–Expectation Maximization algorithm to achieve the restoration estimation of the SXI-simulated observation image,whose mapping relationship with the target image is established by the patch *** Classification–Expectation Maximization algorithm is used to select multiple patch clusters with the same distribution and then train different patch estimators so as to improve the accuracy of the *** results showed that our image restoration algorithm is superior to other classical image restoration algorithms in the SXI-simulated observation image restoration task,according to the peak signal-to-noise ratio and structural *** restoration results of SXI-simulated observation images are used in the tangent fitting approach and the computed tomography approach toward magnetospheric reconstruction techniques,significantly improving

关键词： Solar wind Magnetosphere Ionosphere Link Explorer(SMILE) soft X-ray imager magnetopause image restoration

Online Nonstop Task Management for Storm-Based Distributed Stream Processing Engines

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Journal of Computer Science & Technology 2024年第1期39卷 116-138页

作者：张洲金培权谢希科王晓亮刘睿诚万寿红 School of Computer Science and Technology University of Science and Technology of ChinaHefei 230026China Key Laboratory of Electromagnetic space information Chinese Academy of SciencesHefei 230026China

Most distributed stream processing engines(DSPEs)do not support online task management and cannot adapt to time-varying data ***,some studies have proposed online task deployment algorithms to solve this ***,these approaches do not guarantee the Quality of Service(QoS)when the task deployment changes at runtime,because the task migrations caused by the change of task deployments will impose an exorbitant *** study one of the most popular DSPEs,Apache Storm,and find out that when a task needs to be migrated,Storm has to stop the resource(implemented as a process of Worker in Storm)where the task is *** will lead to the stop and restart of all tasks in the resource,resulting in the poor performance of task *** to solve this problem,in this pa-per,we propose N-Storm(Nonstop Storm),which is a task-resource decoupling DSPE.N-Storm allows tasks allocated to resources to be changed at runtime,which is implemented by a thread-level scheme for task ***,we add a local shared key/value store on each node to make resources aware of the changes in the allocation ***,each resource can manage its tasks at *** on N-Storm,we further propose Online Task Deployment(OTD).Differ-ing from traditional task deployment algorithms that deploy all tasks at once without considering the cost of task migra-tions caused by a task re-deployment,OTD can gradually adjust the current task deployment to an optimized one based on the communication cost and the runtime states of *** demonstrate that OTD can adapt to different kinds of applications including computation-and communication-intensive *** experimental results on a real DSPE cluster show that N-Storm can avoid the system stop and save up to 87%of the performance degradation time,compared with Apache Storm and other state-of-the-art *** addition,OTD can increase the average CPU usage by 51%for computation-intensive application

关键词： distributed stream processing engine(DSPE) Apache Storm online task migration online task deployment

Improving path planning efficiency for underwater gravity-aided navigation based on a new depth sorting fast search algorithm

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Defence Technology（防务技术） 2024年第2期32卷 285-296页

作者： Xiaocong Zhou Wei Zheng Zhaowei Li Panlong Wu Yongjin Sun School of Automation Nanjing University of Science and TechnologyNanjing210094China China academy of Aerospace Science and Innovation Beijing100176China Qian Xuesen Laboratory of space Technology China Academy of Space TechnologyBeijing100094China School of Electronics and information Engineering Harbin Institute of TechnologyHarbin150001China

This study focuses on the improvement of path planning efficiency for underwater gravity-aided ***,a Depth Sorting Fast Search(DSFS)algorithm was proposed to improve the planning speed of the Quick Rapidly-exploring Random Trees*(Q-RRT*)algorithm.A cost inequality relationship between an ancestor and its descendants was derived,and the ancestors were filtered ***,the underwater gravity-aided navigation path planning system was designed based on the DSFS algorithm,taking into account the fitness,safety,and asymptotic optimality of the routes,according to the gravity suitability distribution of the navigation ***,experimental comparisons of the computing performance of the ChooseParent procedure,the Rewire procedure,and the combination of the two procedures for Q-RRT*and DSFS were conducted under the same planning environment and parameter conditions,*** results showed that the computational efficiency of the DSFS algorithm was improved by about 1.2 times compared with the Q-RRT*algorithm while ensuring correct computational results.

关键词： Depth Sorting Fast Search algorithm Underwater gravity-aided navigation Path planning efficiency Quick Rapidly-exploring Random Trees*(QRRT*)