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Optimized sparse polynomial chaos expansion with entropy regularization

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Advances in Aerodynamics 2022年第1期4卷 39-57页

作者： Sijie Zeng xiaojun duan Jiangtao Chen Liang Yan College of Liberal Arts and Sciences National University of Defense TechnologyChangshaChina China Aerodynamics Research and Development Center MianyangChina

Sparse Polynomial Chaos Expansion(PCE)is widely used in various engineering fields to quantitatively analyse the influence of uncertainty,while alleviating the problem of dimensionality ***,current sparse PCE techniques focus on choosing features with the largest coefficients,which may ignore uncertainties propagated with high order ***,this paper proposes the idea of selecting polynomial chaos basis based on information entropy,which aims to retain the advantages of existing sparse techniques while considering entropy change as output uncertainty.A novel entropy-based optimization method is proposed to update the state-of-the-art sparse PCE *** work further develops an entropy-based synthetic sparse model,which has higher computational *** benchmark functions and a computational fluid dynamics(CFD)experiment are used to compare the accuracy and efficiency between the proposed method and classical *** results show that entropy-based methods can better capture the features of uncertainty propagation,improving accuracy and reducing sparsity while avoiding over-fitting problems.

关键词： entropy polynomial chaos

Basic performance of BeiDou-2 navigation satellite system used in LEO satellites precise orbit determination

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Chinese Journal of Aeronautics 2014年第5期27卷 1251-1258页

作者： Liu Junhong Gu Defeng Ju Bing Yao Jing duan xiaojun Yi Dongyun College of Science National University of Defense Technology

The visibility for low earth orbit（LEO） satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system（GPS）. In addition, the spaceborne receivers＇ observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satellites orbits. The precise orbit determination（POD） results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional（3D） accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about30 cm. As for the precise relative orbit determination（PROD）, the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demonstrates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit（GEO） satellites is illustrated for POD.

关键词： BeiDou-2 Geostationary earth orbit satellites Global positioning system Low earth orbit satellites Precise orbit determination Precise relative orbit determination

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Precise orbit determination for TH02-02 satellites based on BDS3 and GPS observations

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Chinese Journal of Aeronautics 2023年第5期36卷 475-485页

作者： Houzhe ZHANG Bing JU Defeng GU Ying LIU Kai SHAO xiaojun duan Zhiyong HUANG College of Science National University of Defense TechnologyChangsha 410073China National Key Laboratory of Science and Technology on Aerospace Flight Dynamics Beijing Aerospace Control CenterBeijing 100094China MOE Key Laboratory of TianQin Mission TianQin Research Center for Gravitational PhysicsFrontiers Science Center for TianQinCNSA Research Center for Gravitational WavesSun Yat-sen University(Zhuhai Campus)Zhuhai 519082China School of Artificial Intelligence Sun Yat-sen University(Zhuhai Campus)Zhuhai 519082China School of Physics and Astronomy Sun Yat-sen University(Zhuhai Campus)Zhuhai 519082China Information Engineering University Zhengzhou 450001China

The Tianhui-202(TH02-02)satellite formation,as a supplement to the microwave mapping satellite system Tianhui-201(TH02-01),is the first Interferometric Synthetic Aperture Radar(InSAR)satellite formation-flying system that supports the tracking of BeiDou global navigation Satellite system(BDS3)new B1C and B2a ***,the twin TH02-02 satellites also support the tracking of Global Positioning System(GPS)L1&L2 and BDS B1I&B3I *** the spaceborne receiver employs two independent boards to track the Global Navigation Satellite System(GNSS)satellites,we design an orbit determination strategy by estimating independent receiver clock offsets epoch by epoch for each GNSS to realize the multi-GNSS data fusion from different *** performance of the spaceborne receiver is evaluated and the contribution of BDS3 to the kinematic and reduced-dynamic Precise Orbit Determination(POD)of TH02-02 satellites is *** tracking data onboard shows that the average number of available BDS3 and GPS satellites are 8.7 and 9.1,*** carrier-to-noise ratio and carrier phase noise of BDS3 B1C and B2a signals are comparable to those of ***,strong azimuth-related systematic biases are recognized in the pseudorange multipath errors of B1C and *** pseudorange noise of BDS3 signals is better than that of GPS after eliminating the multipath errors from specific *** the GPS-based reduced-dynamic orbit with single-receiver ambiguity fixing technique as a reference,the results of BDS3-only and BDS3+GPS combined POD are *** Root Mean Square(RMS)of orbit comparison of BDS3-based kinematic and reduced-dynamic POD with reference orbit are better than 7 cm and 3 cm in three-Dimensional direction(3D).The POD performance based on B1C&B2a data is comparable to that based on B1I&*** precision of BDS3+GPS combined kinematic orbit can reach up to 3 cm(3D RMS),which has a more than 25%improvement relative to the GPS-only *** addi

关键词： BDS3 Multi-GNSS Precise orbit determination Spaceborne GNSS receiver TH02-02

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Tipping Point Detection Using Reservoir Computing

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Research 2024年第1期2023卷 779-790页

作者： Xin Li Qunxi Zhu Chengli Zhao Xuzhe Qian Xue Zhang xiaojun duan Wei Lin College of Science National University of Defense TechnologyChangshaHunan 410073China Research Institute of Intelligent Complex Systems and MOE Frontiers Center for Brain Science Fudan UniversityShanghai 200433China Shanghai Artificial Intelligence Laboratory Shanghai 200232China School of Mathematical Sciences SCMSSCAMand CCSBFudan UniversityShanghai 200433China

Detection in high fidelity of tipping points,the emergence of which is often induced by invisible changes in internal structures or/and external interferences,is paramountly beneficial to understanding and predicting complex dynamical systems(CDSs).Detection approaches,which have been fruitfully developed from several perspectives(e.g.,statistics,dynamics,and machine learning),have their own advantages but still encounter difficulties in the face of high-dimensional,fluctuating ***,using the reservoir computing(RC),a recently notable,resource-conserving machine learning method for reconstructing and predicting CDSs,we articulate a model-free framework to accomplish the detection only using the time series observationally recorded from the underlying unknown CDSs.

关键词： computing record ping

Systems science in the new era: intelligent systems and big data

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Science China(Information Sciences) 2024年第3期67卷 308-310页

作者： Wenwu YU Duxin CHEN Hongzhe LIU He WANG Jinde CAO Zengru DI xiaojun duan Bin JIA Xiaodong DING Yiguang HONG School of Mathematics Southeast University Purple Mountain Laboratories International Academic Center of Complex Systems Beijing Normal University College of Science National University of Defense Technology School of Systems Science Beijing Jiaotong University Business School University of Shanghai for Science and Technology Department of Control Science and Engineering Tongji University

This study introduces the emergence, research challenges,and future development of intelligent systems and big data(ISBD) and discusses the significance of ISBD to systems science. To this end, an overview of systems science is first presented, followed by the conclusion that the development of artificial intelligence(AI) has promoted the derivation and development of intelligent systems(ISs).

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基于先验融合的Bayes递归精度评定方法

弹道学报 2005年第4期17卷 6-10,21页

作者：段晓君国防科技大学理学院数学与系统科学系长沙410073

制导工具误差分离与落点精度分析是武器精度评定中最为关心的问题之一.为充分融合观测信息进行精度评估,在对制导工具误差系数的测试值进行先验融合的基础上,结合遥外弹道观测数据求解制导工具误差系数,并将相应的制导工具误差与弹道差... 详细信息

制导工具误差分离与落点精度分析是武器精度评定中最为关心的问题之一.为充分融合观测信息进行精度评估,在对制导工具误差系数的测试值进行先验融合的基础上,结合遥外弹道观测数据求解制导工具误差系数,并将相应的制导工具误差与弹道差的Bayes实时融合结果进行了比较.建立了递归的落点精度评估方法,将由地面测试先验导出的落点先验与落点观测数据进行加权融合,给出落点评定结果.理论分析和仿真计算表明,信息融合后得出的评定结果更加稳健.

关键词：先验融合 Bayes方法精度评定

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BDS3-based precise orbit determination for LEO satellites with single-receiver ambiguity fixing

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BDS3-based precise orbit determination for LEO satellites wi...

Surface Defects Classification Using Transfer Learning and Deep Sparse Coding

第十四届中国卫星导航年会

作者： Houzhe Zhang Kai Shao xiaojun duan College of Science National University of Defense Technology School of Physics and Astronomy Sun Yat-sen University (Zhuhai Campus)

Single-receiver ambiguity fixing can enhance the observation geometric constraint, and improve the orbit accuracy of low Earth Orbit(LEO) satellites. We propose a single-receiver ambiguity fixing method by taking the carrier phase residual as the index to choose reference in the single-difference ambiguities. The ambiguity fixing performance and Precise Orbit Determination(POD) is verified by using the spaceborne BDS3 observation from Tianhui 02-02 satellites. The ambiguity fixing success rates for BDS3 wide-and narrow-lanes are98% and 89%. Taking the GPS-based orbit with single-receiver ambiguity fixing as a reference, the orbit comparison shows that the accuracy of radial, tangential and normal directions of BDS3-based POD are improved by 26%, 42% and 52% with the single-receiver ambiguity fixing, and the three-dimensional RMS of orbit difference is improved from 2.5 cm to 1.4 cm. The baseline from the orbit difference is evaluate by comparing to the baseline derived from the doubledifference GPS-based precise relative orbit determination. The radial,tangential and normal accuracy of baseline solution are improved by27%, 45% and 46% when fixing ambiguity. The 3D RMS of baseline difference is reduced from 7.6 mm to 4.3 mm. The single-receiver ambiguity fixing can be performed by using our ambiguity fixing method, and the accuracy of BDS3-based POD and baseline can be improved.

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Surface Defects Classification Using Transfer Learning and D...

Quality analysis of multi-GNSS observation data based on iGMAS

第40届中国控制会议

作者： Qizi Huangpeng xiaojun duan Wenwei Huang College of Arts and Science National University of Defense Technology College of Basic Military Education National University of Defense Technology

Defect classification is an important part of automated surface defect detection ***,the types of surface defects of industrial products are complex and diverse,and the correct defect type classification can help to subsequently extract the characteristic of ***,defect classification can help to count the number of defect modes automatically and provide data support for the precise maintenance of product *** to the large number of surface defects and the small difference between defect types,traditional classification methods are difficult to classify defect ***,in order to improve the accuracy of defect image classification,this paper proposes a defect image classification method based on transfer learning and sparse ***,a deep CNN feature extraction algorithm for defect images is proposed in combination with transfer ***,the deep CNN features of the defect image are dimension-reduced and sparsely optimized using the sparse coding techniques,and the sparse CNN features are ***,the sparse CNN features are classified to realize the defect type determination using the linear *** accuracy of the proposed method is verified by using a steel surface defect image benchmark database,and the effectiveness of the proposed method is proved.

关键词： Surface Defects Classification Transfer Learning Sparse Coding

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Quality analysis of multi-GNSS observation data based on iGM...