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Determining geocenter motion using combined ground and spaceborne GPS observations with ambiguity resolution

Advances in Space Research 2025年第11期75卷 7903-7916页

作者： Guo, Shiwei Fan, Lei Li, Zongnan Fang, Xinqi Huo, Chenshu Shi, Chuang School of Space and Earth Sciences Beihang University Beijing102206 China Key Laboratory of Navigation and Communication Fusion Technology Ministry of Industry and Information Technology Beijing100191 China College of Electronic Science National University of Defense Technology Changsha410005 China School of Electronic and Information Engineering Beihang University Beijing100191 China

Owing to the dense global tracking network and the abundant satellites providing continuous observations, the Global Navigation Satellite system (GNSS) has the potential to measure geocenter motion. However, the high altitude of GNSS satellites and the estimation of phase ambiguities compromise the quality of the estimated geocenter coordinates (GCC). This study conducted a combined zero-difference processing of ground observations from 98 global stations and spaceborne observations from four low Earth orbiters (LEOs), investigating the impact of integer ambiguity resolution and LEO configuration on GPS-derived GCC estimates. The ambiguity resolution in the double-difference mode between ground stations and one LEO can significantly improve the observability of GCC estimates, reducing the formal errors by 69.4 %, 69.4 % and 55.0 % for the X, Y and Z components, respectively. The faster relative motion between LEO and GPS satellites contributes to a faster change of tracking geometry. Integrating four LEOs into ground network, the formal errors of GCC parameters are reduced by 77.8 %, 78.2 % and 50.5 % for the X, Y and Z components, respectively. For the most concerned GCC Z component, its correlation with the B1C empirical parameter is reduced from 0.69 to 0.41, demonstrating that the GCC Z component is more separable from the orbital parameters. Besides, the 5th and 7th draconitic harmonics of the Z component are mitigated by 67.0 % and 73.5 %, respectively. The derived annual signal shows a good consistency with the external SLR-based solution, and the amplitude differences are only 0.9 mm, 1.6 mm and 1.2 mm for the X, Y and Z components, respectively. © 2025

关键词： Global positioning system

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PARTICLE-ELLIPSE IOU LOSS FOR ACCURATE DROGUE DETECTION

PARTICLE-ELLIPSE IOU LOSS FOR ACCURATE DROGUE DETECTION

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2024 CSAA/IET International Conference on Aircraft Utility systems, AUS 2024

作者： Tan, Ke Fan, Jiafei Fan, Boqian Ji, Kang Aviation Key Laboratory of Science and Technology On Aero Electromechanical System Integration Nanjing Engineering Institute of Aircraft Systems AVIC Nanjing China

Drogue detection is widely used in autonomous aerial refueling and drogue control, with high accuracy and speed requirements. However, since the image of the drogue is usually an ellipse with different axis ratios, the Intersection over Union (loU) based on rectangular bounding boxes can hardly accurately measure the similarity between the predicted region and the ground truth. To solve the above issue, we propose a novel particle-ellipse loU (PEloU) loss for drogue detection in this work. By setting particles on the image and calculating the proportion occupied by the overlapping part, an estimation of true IoU for two elliptical regions can be obtained. Furthermore, an improved network based on YOLOv8 was designed, and the PEloU loss was integrated into the model. Finally, a drogue dataset was created containing real images, which was used to perform experiments. The extensive experiments demonstrate that the method proposed in this paper not only outperforms the baseline but also operates efficiently in real-time on edge devices. © The Institution of engineering & technology 2024.

关键词： Image enhancement

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Coalition Formation Game for Reconnaissance and Attack Task Allocation in Heterogeneous UAV Swarm 11th

Coalition Formation Game for Reconnaissance and Attack Tas...

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11th China Conference on Command and Control, C2 2023

作者： Chen, Jiaxin Fang, Tao Li, Qingwei He, Jiafan Xia, Zhijie Mao, Yiming Science and Technology on Information Systems Engineering Laboratory Nanjing210023 China Unit 94860 of PLA Nanjing210008 China

ISBN: (纸本)9789819990207

Unmanned aerial vehicle (UAV) swarm is extensively used in several military applications, e.g., battlefield reconnaissance and attack. In this article, a heterogeneous UAV swarm consisting of the reconnaissance UAVs (RUAVs), unmanned combat aerial vehicles (UCAVs) and reconnaissance combat integrated UAVs (RCIUAVs) is considered. The cooperative reconnaissance and attack task allocation problem is formulated as a coalition formation game (CFG) and the partially cooperative order is proposed. Then, we prove that the formulated CFG is an exact potential game (EPG) which exists the stable coalition partition. The partially cooperative coalition formation algorithm is proposed. The simulation results show the validity of the proposed game model and algorithm. © Chinese Institute of Command and Control 2024.

关键词： Unmanned aerial vehicles (UAV)

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Co-variability Between the Broad Absorption Lines and Narrow Absorption Lines

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Research in Astronomy and Astrophysics 2024年第9期24卷 99-105页

作者： Bo-Lin Qin Jing Li Wei-Jian Lu Guangdong Country Garden School Foshan 528312China Laboratory for Relativistic Astrophysics Physical Science and Technology CollegeGuangxi UniversityNanning 530004China School of Information Engineering Baise UniversityBaise 533000China

We investigate the relationship between the variability of broad absorption lines(BALs)or narrow absorption lines(NALs)and that of continuum using a data set of two-epoch SDSS spectra containing 134 C IV NAL-BAL *** analysis reveals an anti-correlation between the fractional equivalent width(EW)variations in NALs(or BALs)and the fractional flux variations of the continuum,with Spearman rank correlation coefficients of r=-0.47(p=1E-08)and r=-0.58(p=1E-13),*** addition,we find a positive correlation between the fractional EW variations in NALs and BALs(r=0.72,p=1E-22),and derive a regression equation ΔEW_(NAL)/=0.803ΔEW_(BAL)/+0.008,with an intrinsic scatter of *** results suggest that the variability in the ionizing continuum may play a significant role in the observed changes in C IV NALs and BALs,supporting the idea of photoionization-driven *** co-variability between C IV NALs and BALs may imply that they originate from outflows with similar physical conditions.

关键词： (galaxies:)quasars:absorption lines (galaxies:)quasars:general galaxies:active

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PNSS: Unknown Face Presentation Attack Detection with Pseudo Negative Sample Synthesis

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Computers, Materials & Continua 2025年第5期83卷 3097-3112页

作者： Hongyang Wang Yichen Shi Jun Feng Zitong Yu Zhuofu Tao School of Information Science and Technology Shijiazhuang Tiedao UniversityShijiazhuang050043China Shijiazhuang Key Laboratory of Artificial Intelligence Shijiazhuang Tiedao UniversityShijiazhuang050043China School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai200240China School of Computer Science and Technology Great Bay UniversityDongguan523808China School of Electrical and Computer Engineering University of CaliforniaLos AngelesCA 90095USA

Face Presentation Attack Detection(fPAD)plays a vital role in securing face recognition systems against various presentation *** supervised learning-based methods demonstrate effectiveness,they are prone to overfitting to known attack types and struggle to generalize to novel attack *** studies have explored formulating fPAD as an anomaly detection problem or one-class classification task,enabling the training of generalized models for unknown attack ***,conventional anomaly detection approaches encounter difficulties in precisely delineating the boundary between bonafide samples and unknown *** address this challenge,we propose a novel framework focusing on unknown attack detection using exclusively bonafide facial data during *** core innovation lies in our pseudo-negative sample synthesis(PNSS)strategy,which facilitates learning of compact decision boundaries between bonafide faces and potential attack ***,PNSS generates synthetic negative samples within low-likelihood regions of the bonafide feature space to represent diverse unknown attack *** overcome the inherent imbalance between positive and synthetic negative samples during iterative training,we implement a dual-loss mechanism combining focal loss for classification optimization with pairwise confusion loss as a *** architecture effectively mitigates model bias towards bonafide samples while maintaining discriminative *** evaluations across three benchmark datasets validate the framework’s superior ***,our PNSS achieves 8%–18% average classification error rate(ACER)reduction compared with state-of-the-art one-class fPAD methods in cross-dataset evaluations on Idiap Replay-Attack and MSU-MFSD datasets.

关键词： Face presentation attack detection pseudo negative sample anomaly detection one-class classification

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Optimal Tracking Neuro-Control of Continuous Stirred Tank Reactor systems: A Dynamic Event-Driven Approach

IEEE Transactions on Artificial Intelligence

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IEEE Transactions on Artificial Intelligence 2024年第5期5卷 2117-2126页

作者： Yang, Xiong Zhou, Yingjiang Tianjin University Tianjin Key Laboratory of Intelligent Unmanned Swarm Technology and System School of Electrical and Information Engineering Tianjin300072 China Nanjing University of Posts and Telecommunications College of Automation and College of Artificial Intelligence Nanjing210023 China

It is often challenging to design an optimal tracking controller for the continuous stirred tank reactor (CSTR) system due to its nonlinear nature and physical limitations. This article presents a dynamic event-driven optimal tracking neruo-control scheme for the CSTR system with asymmetric input constraints. Initially, an improved nonquadratic cost function is introduced for the CSTR system to tackle asymmetric control restrictions. Then, a dynamic event-driven mechanism together with the event-driven Hamilton-Jacobi-Bellman equation (ED-HJBE) is proposed. To solve the ED-HJBE, a critic neural network (CNN) is constructed within the critic learning framework. The CNN's weight vector is tuned by combining the gradient descent method and the concurrent learning technique. After that, uniform ultimate boundedness of the tracking error and the CNN's weight estimation error is assured based on the Lyapunov method. Finally, experiment studies are conducted to validate the present optimal tracking neuro-control strategy. © 2023 IEEE.

关键词： Reinforcement learning

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Giant negative electrocaloric effect measured by indirect method in X-ray irradiated P(VDF-TrFE)films

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Journal of Materiomics 2024年第3期10卷 624-631页

作者： Bo Li Bin Yang Hong Zhang Jiajia Zhang Qianjin Wang Weishu Liu Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhenGuangdong 518055China Guangdong Provincial Key Laboratory of Functional Oxide Materials and Devices Southern University of Science and TechnologyShenzhenChina College of Physics and Electronic Information Yunnan Normal UniversityYunnan Kunming 650500China The Science and Technology on Reliability Physics and Application of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research InstituteGuangzhou 510610China

Flexible solid-state cooling devices with high efficiency are attracted to ferroelectric polymers with excellent negative electrocaloric(EC)*** is challenging to obtain a large negative EC effect in ferroelectric polymers due to the lack of tunable techniques.A giant negative EC response was obtained in the poly(vinylidene fluoride-trifluoroethylene)copolymers(P(VDF-TrFE),70/30,in mole ratio)irra-diated with high-energy *** irradiated P(VDF-TrFE)films showed an adiabatic temperature change of-13.5 K at 40 MV/m under a dose of 5 Mrad(1 Mrad=10^(4) J/kg)obtained by the indirect *** significant negative EC effect is attributed to the enhancement of crystalline due to the entry of polymer molecules into the amorphous to crystalline structure and the reduction of heat ca-pacity due to the increase of *** addition,X-ray irradiation improves the dielectric coefficient from 15 to *** research indicates that irradiation can modify the negative EC properties of ferro-electric polymers for solid-state cooling.

关键词： Negative electrocaloric effects X-rays radiation P(VDF-TrFE)films

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User story clustering in agile development:a framework and an empirical study

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Frontiers of Computer science 2023年第6期17卷 43-59页

作者： Bo YANG Xiuyin MA Chunhui WANG Haoran GUO Huai LIU Zhi JIN School of Information Science and Technology Beijing Forestry UniversityBeijing 100083China Engineering Research Center for Forestry Oriented Intelligent Information Processing National Forestry and Grassland AdministrationBeijing 100083China School of Information Science and Technology North China University of TechnologyBeijing 100144China College of Computer Science and Technology Inner Mongolia Normal UniversityHohhot 010020China Department of Computer Science and Software Engineering Swinburne University of TechnologyHawthorn VIC 3122Australia Key Laboratory of High Confidence Software Technologies(Peking University) Ministry of EducationBeijing 100871China Institute of Software School of Computer SciencePeking UniversityBeijing 100871China

Agile development aims at rapidly developing software while embracing the continuous evolution of user requirements along the whole development *** stories are the primary means of requirements collection and elicitation in the agile development.A project can involve a large amount of user stories,which should be clustered into different groups based on their functionality’s similarity for systematic requirements analysis,effective mapping to developed features,and efficient ***,the current user story clustering is mainly conducted in a manual manner,which is time-consuming and subjective to human *** this paper,we propose a novel approach for clustering the user stories automatically on the basis of natural language ***,the sentence patterns of each component in a user story are first analysed and determined such that the critical structure in the representative tasks can be automatically extracted based on the user story *** similarity of user stories is calculated,which can be used to generate the connected graph as the basis of automatic user story *** evaluate the approach based on thirteen datasets,compared against ten baseline *** results show that our clustering approach has higher accuracy,recall rate and F1-score than these *** is demonstrated that the proposed approach can significantly improve the efficacy of user story clustering and thus enhance the overall performance of agile *** study also highlights promising research directions for more accurate requirements elicitation.

关键词： user story agile development user story mapping clustering

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Zincophilic Ti_(3)C_(2)Cl_(2)MXene and anti-corrosive Cu NPs for synergistically regulated deposition of dendrite-free Zn metal anode

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Journal of Materials science & technology 2024年第2期169卷 137-147页

作者： Yunfei Shen Yi Liu Kaisheng Sun Tiantian Gu Gang Wang Yue Yang Jianxiang Pang Yang Zheng Xiaodong Yang Long Chen Key Laboratory for Green Process of Chemical Engineering of Xinjiang Bingtuan School of Chemistry and Chemical EngineeringShihezi UniversityShihezi 832003China Institute for Chemistry Chemnitz University of TechnologyChemnitz 09107Germany CAS Key Laboratory of Functional Materials and Devices for Special Environments Xinjiang Key Laboratory of Electronic Information Materials and DevicesCenter of Materials Science and Optoelectronics EngineeringXinjiang Technical Institute of Physics and Chemistry of CASUrumqi 830011China Key Laboratory of Ecophysics and Department of Physics College of ScienceShihezi UniversityShihezi 832003China

Dendrites growth,chemical corrosion,and hydrogen evolution reaction(HER)on zinc anodes are the main barriers for the development of aqueous zinc-ion batteries(AZIBs).Constructing interfacial protec-tive layer is an effective way to alleviate the side reactions on the ***,Cu/Ti_(3)C_(2)Cl_(2)MXene(CMX)with high zincophilic and hydrophobic property is prepared by the lewis molten salts etching method,and the CMX interface protection layer is constructed by a simple spin *** CMX coat-ing layer can provide abundant nucleation sites and uniformize the charge distribution through the zin-cophilic Ti_(3)C_(2)Cl_(2)MXene matrix,leading to homogenous Zn *** addition,the hydrophobic coat-ing contained anti-corrosive Cu nanoparticles can prevent the Zn anode from the electrolyte,beneficial for suppressing the chemical corrosion and ***,the stable and reversible Zn plating/stripping is achieved for the Zn anode coated by the CMX,which exhibits the lifespan of over 1400 h at 0.5 mA cm^(−2),and even can steadily run for 700 h with 65 mV at 10 mA cm^(−2).Furthermore,CMX@Zn shows a high coulombic efficiency of over 100%for 3800 cycles,which indicates that the CMX@Zn electrode has excellent stability and reversibility of Zn stripping/*** full batteries assembled with ZnCoMnO/C(ZCM)cathodes also exhibits higher capacity(450.6 mAh g^(−1)at 0.1 A g^(−1))and cycle stability(capacity retention of 70%after 1500 cycles).This work enhanced the lifespan of AZIBs and broaden the research of multifunctional coating layer to other secondary batteries based on metal anodes.

关键词： Zinc anode Spin coating Zincophilic MXene Anti-corrosive Cu NPs Multifunctional coating

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Efficient concentration of trace analyte with ordered hotspot construction for a robust and sensitive SERS platform

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International Journal of Extreme Manufacturing 2024年第3期6卷 532-542页

作者： Youdi Hu Yanlei Hu Zhenyu Wang Jiale Yong Wei Xiong Dong Wu Shixiang Xu Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhenGuangdong 518060People’s Republic of China CAS Key Laboratory of Mechanical Behavior and Design of Materials Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education InstitutesDepartment of Precision Machinery and Precision InstrumentationUniversity of Science and Technology of ChinaHefeiAnhui 230027People’s Republic of China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhanHubeiPeople’s Republic of China

Surface-enhanced Raman scattering(SERS)platform,which enables trace analyte detection,has important application *** structuring/modifying the surface of the SERSsubstrate,analyte in highly diluted solutions can be concentrated into localized active areas for highly sensitive ***,subject to the difficulty of the fabrication process,itremains challenging to balance hot-spot construction and the concentration capacity of analyte ***,preparing SERS substrates with densely ordered hot spots andefficient concentration capacity is of great significance for highly sensitive ***,we propose an Ag and fluoroalkyl-modified hierarchical armour substrate(Ag/F-HA),which has a double-layer stacking design to combine analyte concentration with hotspot *** microarmour structure is fabricated by femtosecond-laser processing to serve as asuperhydrophobic and low-adhesive surface to concentrate analyte,while the anodic aluminium oxide(AAO)template creates a nanopillar array serving as dense and ordered hot *** the synergistic action of hot spots and analyte concentration,Ag/F-HA achieves a detectionlimit down to 10^(-7)M doxorubicin(DOX)molecules with a RSD of 7.69%.Additionally,Ag/F-HA exhibits excellent robustness to resist external disturbances such as liquid splash or *** on our strategy,SERS substrates with directional analyte concentrations are further explored by patterning microcone arrays with *** work opens a way to the realistic implementation of SERS in diverse scenarios.

关键词： surface-enhanced Raman scattering anodic aluminium oxide femtosecond laser processing concentration of trace analytes mechanical robustness

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