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Trajectory optimization of near-Earth asteroids exploration by using reusable probes from cislunar space
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作者 Kaiduo WANG Youliang WANG +5 位作者 Bowen DONG Jiening ZHAO Quan JING Mingtao LI Xizheng YU Jianhua ZHENG 《Chinese Journal of Aeronautics》 2025年第3期355-373,共19页
Implementing the flyby to Near-Earth Asteroids (NEAs) with the potential impact risks to the Earth allows for obtaining detailed physical parameters, thereby supporting the high-precision orbit prediction and planetar... Implementing the flyby to Near-Earth Asteroids (NEAs) with the potential impact risks to the Earth allows for obtaining detailed physical parameters, thereby supporting the high-precision orbit prediction and planetary defense strategy. Different from those conducted asteroid flyby missions, in the 12th China Trajectory Optimization Competition (CTOC-12), a NEAs flyby trajectory design problem using reusable probes that depart from a Lunar Distant Retrograde Orbit (DRO) station in the cislunar space was released. The objective was flyby to as many NEAs as possible using up to 20 probes within a total of 10 years. The ∑ team proposed a solution that can explore 47 NEAs using 11 probes, ranking the first in the competition. In this paper, the methods and results from the winning team are introduced, including mission analysis and preliminary design, and low-energy transfer trajectory optimization. In particular, a round-trip trajectory is divided into three phases: deep space transfer, indirect transfer between the Earth to DRO, and DRO phasing and rendezvous. With the combination of global optimization and local optimization algorithms, the required velocity increments to change the orbital planes are effectively reduced, thus increasing the number of the explored NEAs. The final solution of our team is presented and the results are compared with those of the top three teams. The competition demonstrates that the regularization of flyby missions from the cislunar space to explore NEAs with the potential impact risks to the Earth is the feasible and promising. 展开更多
关键词 ASTEROIDS Low-energy transfer Cislunar space Distant Retrograde 0rbit(DRO) Phasing strategy
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Demonstration-enhanced policy search for space multi-arm robot collaborative skill learning
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作者 Tian GAO Chengfei YUE +1 位作者 Xiaozhe JU Tao LIN 《Chinese Journal of Aeronautics》 2025年第3期462-473,共12页
The increasing complexity of on-orbit tasks imposes great demands on the flexible operation of space robotic arms, prompting the development of space robots from single-arm manipulation to multi-arm collaboration. In ... The increasing complexity of on-orbit tasks imposes great demands on the flexible operation of space robotic arms, prompting the development of space robots from single-arm manipulation to multi-arm collaboration. In this paper, a combined approach of Learning from Demonstration (LfD) and Reinforcement Learning (RL) is proposed for space multi-arm collaborative skill learning. The combination effectively resolves the trade-off between learning efficiency and feasible solution in LfD, as well as the time-consuming pursuit of the optimal solution in RL. With the prior knowledge of LfD, space robotic arms can achieve efficient guided learning in high-dimensional state-action space. Specifically, an LfD approach with Probabilistic Movement Primitives (ProMP) is firstly utilized to encode and reproduce the demonstration actions, generating a distribution as the initialization of policy. Then in the RL stage, a Relative Entropy Policy Search (REPS) algorithm modified in continuous state-action space is employed for further policy improvement. More importantly, the learned behaviors can maintain and reflect the characteristics of demonstrations. In addition, a series of supplementary policy search mechanisms are designed to accelerate the exploration process. The effectiveness of the proposed method has been verified both theoretically and experimentally. Moreover, comparisons with state-of-the-art methods have confirmed the outperformance of the approach. 展开更多
关键词 Space multi-arm collaboration Demonstrations .Reinforcement Learning Probabilistic Movement Primitives Relative Entropy Policy Search Policy search mechanism
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Neutron observations from the energetic particle detector on China's Space Station
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作者 GuoHong Shen DongHui Hou +5 位作者 Yuan Chang XianGuo Zhang HuanXin Zhang Bin Yuan BinQuan Zhang Ying Sun 《Earth and Planetary Physics》 2025年第2期460-466,共7页
The energetic particle detector on China's space station can determine the energy, flux, and direction of medium-and highenergy protons, electrons, heavy ions, and neutrons within the path of the station's orb... The energetic particle detector on China's space station can determine the energy, flux, and direction of medium-and highenergy protons, electrons, heavy ions, and neutrons within the path of the station's orbit. It also assesses the linear energy transfer(LET)spectra and radiation dose rates generated by these particles. Neutron detection is a significant component of this work, utilizing a new type of Cs_(2)LiYCl_(6): Ce scintillator material along with plastic scintillators as sensors. In-orbit testing has demonstrated the efficient identification of space neutrons and gamma rays(n/γ). This data plays a crucial role in supporting manned space engineering, scientific research, and other related fields. 展开更多
关键词 China's space station energy particle detector neutron detection heavy ion detection radiation effect detection
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Confined-parallel-space in-situ growth method:a strategy for fabricating high-quality graphene-Cu composite with excellent comprehensive properties
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作者 Tong Zhang Zhen-Dong Shi +8 位作者 Chang-Sheng Xing Yun-Zhong Wu Bin Liu Ye-Kang Guan Yu Jian Jia-Xu Shuang Jie Sheng Li-Dong Wang Wei-Dong Fei 《Rare Metals》 2025年第9期6456-6470,共15页
Graphene-copper(Gr-Cu)composites exhibit significant potential for industrial applications.Among the methods for fabricating Gr-Cu composites,the in-situ growth method stands out as a simple yet effective approach.How... Graphene-copper(Gr-Cu)composites exhibit significant potential for industrial applications.Among the methods for fabricating Gr-Cu composites,the in-situ growth method stands out as a simple yet effective approach.However,graphene converted from liquid or solid molecules by the traditional in-situ growth method often exhibits numerous defects,thereby reducing its effectiveness in enhancing the electrical properties of the composites.To address this issue,we developed an innovative and efficient method,referred to as the“confinedparallel-space in-situ growth(CPS)method,”to grow highquality graphene and fabricate high-conductivity Gr-Cu composites.Oleic acid was chosen as the small molecular carbon source and confined between copper sheets obtained by rolling dendritic copper powder.This carbon source underwent conversion into oriented,high-quality graphene in the confined space at high temperature.The high-quality graphene sheets serve as continuous electron transport channels,significantly improving the conductivity of the composite.The composite prepared by the CPS method(CPS-composite)demonstrates unique conductivity,exceeding that of standard annealed copper at temperatures above 40℃and notably outperforming it by 3.2%at160℃.In addition,compared to the composite with a similar carbon content prepared by the traditional in-situ growth method,the yield strength of the CPS-composite increased by 23.6%,while the strengthening efficiency of graphene improved by 146.6%,achieving an ultrahigh value of 489 at a carbon volume fraction of 0.086 vol%.The CPS method emerges as a novel strategy for fabricating high-performance,low-cost,and large-scale graphene-copper composites using small molecular carbon sources,making it suitable for industrial production. 展开更多
关键词 Graphene-Cu composite Confined-parallel-space In-situ growth Electrical conductivity Strengthening mechanism
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2.5 m Space Station Co-orbiting Coaxial Telescope
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作者 Dingqiang Su Hua Bai +3 位作者 Xiangyan Yuan Genrong Liu Xiangqun Cui Xiaojie Jiao 《Research in Astronomy and Astrophysics》 2025年第5期1-5,共5页
The China Space Station Telescope(CSST) is primarily designed for large-scale multi-color imaging and seamless spectroscopic survey, while also accommodating observations with an integral field spectrograph(IFS), mult... The China Space Station Telescope(CSST) is primarily designed for large-scale multi-color imaging and seamless spectroscopic survey, while also accommodating observations with an integral field spectrograph(IFS), multichannel imaging, direct imaging of exoplanets, and terahertz-band observations. It is scheduled to be launched in about 2 yr. The telescope is equipped with a variety of terminal instruments. It has important scientific missions but limited observation time, so it is suggested to develop a 2.5 m coaxial telescope that will be co-orbiting with the space station. This additional telescope will mainly focus on time-domain surveys and IFS surveys. Its development budget is lower than the current 2 m off-axis telescope, CSST, but it offers superior system performance. Within the limited operational lifespan of the space station, it can significantly enhance the existing survey efficiency. Like the CSST, this telescope will be able to do multi-color imaging survey, and time-domain surveys are also under consideration. 展开更多
关键词 space vehicles instruments-telescopes-surveys
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Laser Cooling Alkaline-earth Atoms for Optical Clock in Chinese Space Station
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作者 Guodong Zhao Jian Xia +19 位作者 Yun Liu Yongzhuang Zhou Chihua Zhou Feng Guo Wenhai Wang Dejing He Min Feng Ting Liang Jie Ren Qinfang Xu Junwei Meng Feng Gao Yong Shen Xiaotong Lu Benquan Lu Yebing Wang Xiaohua Hu Wei Tan Hongxin Zou Hong Chang 《Chinese Physics Letters》 2025年第6期63-69,共7页
This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electric... This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electrical unit,have a total volume of 306 L and a total mass of 163.8 kg.These compact and robust units can overcome mechanical vibrations and temperature fluctuations during space launch.The laser sources of the optical unit are composed of diode lasers,and the injection locking of slave lasers is automatically performed by a program.In the experiment,a blue magneto-optical trap of cold atoms was achieved,with the atom numbers estimated to be approximately(1.50±0.13)×10^(6) for 87Sr and(8.00±0.56)×10^(6) for 88Sr.This work establishes a foundation for atomic confinement and high-precision interrogation in space-based optical clocks and expands the frontiers of cold atom physics in microgravity. 展开更多
关键词 STRONTIUM diode lasersand laser cooling optical clock slave lasers alkaline earth atoms Chinese space station injection locking
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Interference Pattern of Floquet Modes in Frequency Space
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作者 Du-Yi Ou-Yang Yan-Hua Zhou +4 位作者 Ya Zhang Xiao-Tong Lu Hong Chang Tao Wang Xue-Feng Zhang 《Chinese Physics Letters》 2025年第6期19-26,共8页
Wave-particle duality is one of the key features of quantum physics,characterized by the interference pattern.Meanwhile,Floquet spectroscopy is typically studied in the high-frequency region because the Floquet sideba... Wave-particle duality is one of the key features of quantum physics,characterized by the interference pattern.Meanwhile,Floquet spectroscopy is typically studied in the high-frequency region because the Floquet sidebands are very sharp,behaving like“particles”in frequency space,and no interference phenomena are observed.Here,we consider the larger quantum fluctuation region where the Floquet sidebands are broader,making interference between them possible.With the help of an optical lattice clock experimental platform and numerical simulations,such interference of Floquet modes in frequency space is clearly observed.Additionally,it exhibits many exotic phenomena,such as large Floquet sidebands between integer ones,sensitivity to the initial phase,and corresponding emergent symmetries.To analytically elucidate this,we propose the Floquet channel interference hypothesis,which surprisingly matches quantitatively well with both experimental and numerical results.Our research paves the way for developing a new type of interferometer that could be applicable to other Floquet systems. 展开更多
关键词 wave particle duality interference pattern larger quantum fluctuation region frequency space quantum physicscharacterized optical lattice clock experimental floquet sidebands interference phenomena
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Identification of small impact craters in Chang’e-4 landing areas using a new multi-scale fusion crater detection algorithm
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作者 FangChao Liu HuiWen Liu +7 位作者 Li Zhang Jian Chen DiJun Guo Bo Li ChangQing Liu ZongCheng Ling Ying-Bo Lu JunSheng Yao 《Earth and Planetary Physics》 2026年第1期92-104,共13页
Impact craters are important for understanding the evolution of lunar geologic and surface erosion rates,among other functions.However,the morphological characteristics of these micro impact craters are not obvious an... Impact craters are important for understanding the evolution of lunar geologic and surface erosion rates,among other functions.However,the morphological characteristics of these micro impact craters are not obvious and they are numerous,resulting in low detection accuracy by deep learning models.Therefore,we proposed a new multi-scale fusion crater detection algorithm(MSF-CDA)based on the YOLO11 to improve the accuracy of lunar impact crater detection,especially for small craters with a diameter of<1 km.Using the images taken by the LROC(Lunar Reconnaissance Orbiter Camera)at the Chang’e-4(CE-4)landing area,we constructed three separate datasets for craters with diameters of 0-70 m,70-140 m,and>140 m.We then trained three submodels separately with these three datasets.Additionally,we designed a slicing-amplifying-slicing strategy to enhance the ability to extract features from small craters.To handle redundant predictions,we proposed a new Non-Maximum Suppression with Area Filtering method to fuse the results in overlapping targets within the multi-scale submodels.Finally,our new MSF-CDA method achieved high detection performance,with the Precision,Recall,and F1 score having values of 0.991,0.987,and 0.989,respectively,perfectly addressing the problems induced by the lesser features and sample imbalance of small craters.Our MSF-CDA can provide strong data support for more in-depth study of the geological evolution of the lunar surface and finer geological age estimations.This strategy can also be used to detect other small objects with lesser features and sample imbalance problems.We detected approximately 500,000 impact craters in an area of approximately 214 km2 around the CE-4 landing area.By statistically analyzing the new data,we updated the distribution function of the number and diameter of impact craters.Finally,we identified the most suitable lighting conditions for detecting impact crater targets by analyzing the effect of different lighting conditions on the detection accuracy. 展开更多
关键词 impact craters Chang’e-4 landing area multi-scale automatic detection YOLO11 Fusion algorithm
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Comparison of atmospheric gravity wave event statistics between Dandong and Lhasa
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作者 YiXuan Chen Chang Lai +2 位作者 QinZeng Li JiYao Xu Wei Yuan 《Earth and Planetary Physics》 2026年第1期176-185,共10页
Using a recognition model of atmospheric gravity waves(AGWs),we identified 519 AGW events from the OH airglow images observed at the Dandong and Lhasa stations from 2015 to 2017.The 317 AGW events detected at the Dand... Using a recognition model of atmospheric gravity waves(AGWs),we identified 519 AGW events from the OH airglow images observed at the Dandong and Lhasa stations from 2015 to 2017.The 317 AGW events detected at the Dandong station have wavelengths ranging from 30 to 60 km,periods from 14 to 20 min,horizontal speeds from 30 to 60 m/s,and relative intensities from 0.4%to 0.6%,respectively.The parameters of 202 events recorded at the Lhasa station mainly vary within 15-35 km in horizontal wavelength,4-6 min in period,40-100 m/s in horizontal velocity,and 0.1%-0.3%in relative intensity.The occurrence rate peaks in winter and summer at Dandong and the peak in summer are absent at Lhasa because of the lack of convective weather.The seasonal propagation directions of the waves are influenced by both the wind field-filtering effect and the distribution of wave sources.In spring,because of the southeastward background wind field,fewer southeastward events are observed at the Dandong station.The situation at the Lhasa station is similar.In summer,both the Lhasa and Dandong stations are dominated by northeastward AGWs,which can be attributed to the southwestward wind.In autumn,ray-tracing results show that the events at Dandong mainly originate from wind shear,whereas the events at the Lhasa station are triggered by convective weather.The location of the wave sources determines the trend of the propagation directions at the Dandong and Lhasa stations in autumn.In winter,because of the eastward wind,more events are propagating to the southwest at the Dandong station. 展开更多
关键词 atmospheric gravity waves backward ray-tracing method wind field filtering convective precipitation
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Spatiotemporal characteristics of atmospheric CO_(2) under the influence of different industrial emission sources using lidar remote sensing in Nanping,China
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作者 Saifen Yu DaiHao Yu +3 位作者 Qiuwei xia Yixiang Chen Zhen Zhang Haiyun Xia 《Journal of Environmental Sciences》 2026年第1期490-501,共12页
Atmospheric CO_(2) concentrations are predominantly regulated by multiple emission sources,with industrial emis-sions representing a critical anthropogenic driver that significantly influences temporal and spatial het... Atmospheric CO_(2) concentrations are predominantly regulated by multiple emission sources,with industrial emis-sions representing a critical anthropogenic driver that significantly influences temporal and spatial heterogeneity in regional CO_(2) patterns.This study investigated the spatiotemporal distribution of atmospheric CO_(2) in Pucheng and Nanping industrial parks,Nanping City,by conducting field experiments using two coherent differential absorption lidars from 1 August to 31 October 2024.Results showed that the spatial distributions of CO_(2) emis-sions within a 3 km radius were mapped,and the local diffusion processes were clarified.CO_(2) patterns varied differently in two industrial parks over the three-month period:Average CO_(2) concentrations in non-emission areas were 422.4 ppm in Pucheng and 408.7 ppm in Nanping,with the former experiencing higher and more variable carbon emissions;Correlation analysis indicated that synthetic leather factories in Pucheng contributed more to SO_(2) and NO_(x) levels compared to the chemical plant in Nanping;In Pucheng,CO_(2) concentrations were transported from the north at ground-level wind speeds exceeding 4 m/s,while in Nanping,the concentrations dispersed gradually with increasing wind speeds;Forward trajectory simulations revealed that the peak-emission from Pucheng primarily affected southern Fujian,northeastern Jiangxi,and southern Anhui,while the peak-emission from Nanping influenced central and western Fujian and northeastern Jiangxi.Besides,emissions in both industrial parks were higher on weekdays and lower on weekends,reflecting changes in industrial activi-ties.The study underscores the potential of lidar technology for providing detailed insights into CO_(2) distribution and the interactions between emissions,wind patterns,and carbon transport. 展开更多
关键词 LIDAR CO_(2) Wind field Spatiotemporal variations Carbon emission
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Global thermospheric density response to the May 2024 extreme storm:TianMu-1 constellation observations
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作者 JiangZhao Ai XianGuo Zhang +8 位作者 YongPing Li YueQiang Sun WenLu Bai XiaoYu Guo JiaoJiao Zhang XiaoLiang Zheng Jia Li YuJie Wang XinChun Tang 《Earth and Planetary Physics》 2026年第1期105-116,共12页
In this study,we analyze the impact of the May 2024 geomagnetic storm on the thermospheric mass density by using TianMu-1 constellation satellite(TM02,TM06,TM07,TM11,TM15)observations.These observations reveal intense... In this study,we analyze the impact of the May 2024 geomagnetic storm on the thermospheric mass density by using TianMu-1 constellation satellite(TM02,TM06,TM07,TM11,TM15)observations.These observations reveal intense large-scale traveling atmospheric disturbances(TADs)originating at high latitudes and propagating equatorward.Observations by TM02 captured the evolution of a TAD structure:An initial amplitude of~3.89×10^(-12)kg/m^(3)at hundred-kilometer scale subsequently intensified to 4.78×10^(-12)kg/m^(3),with the spatial extent expanding to the thousand-kilometer level.Significant hemispheric asymmetry was observed:the absolute density was higher predominantly in the northern hemisphere(TM02,TM06,TM07,TM11),whereas the difference in the relative density consistently showed greater enhancements in the southern hemisphere across all satellites,with the maximum north-south density differences exceeding 195%-640%above 60°latitude.In conjunction with SuperDARN(Super Dual Auroral Radar Network)observations,this striking hemispheric asymmetry can likely be attributed to disparities in plasma convection patterns between the two hemispheres.Furthermore,density perturbation characteristics exhibited strong local time(LT)dependence:Near noon(~10.7 LT,TM02 descending),the northern hemisphere onset preceded the southern onset.Conversely,near dusk(~17.6 LT,TM15 descending),the southern onset led the northern onset by approximately 3 hours.Ascending orbits(TM02,TM06,TM07,TM15)typically yielded larger global density enhancements compared with smaller southern-confined enhancements during descending orbits.Satellite TM11 showed comparable perturbations in both ascending and descending orbits.By leveraging its unique orbital architecture,the TianMu-1 constellation enables global near-simultaneous multi-LT sampling,providing a robust data foundation for both scientific research and engineering applications. 展开更多
关键词 TianMu-1 constellation thermosphere density magnetic storm hemispheric asymmetry traveling atmospheric disturbances
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A 32‑channel charge‑sensitive amplifier for delay‑line readout of parallel plate avalanche counter array
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作者 Yue‑Zhao Zhang Peng Ma +8 位作者 Zhuang‑Yu Lin Zhen‑Fei Tan Xing‑Chi Han Chen Liu Shuo Wang Da‑Peng Sun Zhi‑Quan Li En‑Hong Wang Shou‑Yu Wang 《Nuclear Science and Techniques》 2026年第1期164-179,共16页
A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete... A 32-channel charge-sensitive amplifier(CSA)is designed for fast timing in the delay-line readout of a parallel plate avalanche counter(PPAC)array.It is realized on a PCB with operational amplifiers and other discrete components.Each channel consists of an integrator,a pole-zero cancellation net,and a linear amplification stage,which can be adapted to accommodate either positive or negative input signals.The RMS equivalent input noise charges are 3.3 fC,the conversion gains are approximately±2 mV∕fC,and the intrinsic time resolution reaches 32 ps.In the prototype PPAC application,the CSA performs as well as the commercial FTA820A amplifier,providing a position resolution as good as 0.17 mm,and exhibiting reliable stability during several hours of continuous data acquisition. 展开更多
关键词 Charge-sensitive amplifier Fast timing Parallel plate avalanche counter Delay-line Discrete components
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Solar EUV flux from the triple ionosophere PhotoMeter onboard the Fengyun-3E satellite
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作者 Fang Jiang Tian Mao +5 位作者 JinSong Wang XiuQing Hu Qian Song LiPing Fu Nan Jia TianFang Wang 《Earth and Planetary Physics》 2026年第1期126-135,共10页
The Triple Ionosphere Photometer(TRIPM)is a scientific payload aboard the Fengyun-3E(FY-3E)satellite,which operates in a dawn−dusk orbit.It is primarily designed for nadir observations of airglow emissions at OI 135.6... The Triple Ionosphere Photometer(TRIPM)is a scientific payload aboard the Fengyun-3E(FY-3E)satellite,which operates in a dawn−dusk orbit.It is primarily designed for nadir observations of airglow emissions at OI 135.6 nm and N_(2)Lyman-Birge-Hopfield(LBH)bands.Due to the satellite’s dawn−dusk orbital characteristics,most of TRIPM’s field of view remains in a semi-illuminated condition.Therefore,compared with airglow data of the same bands acquired under purely daytime or nighttime conditions,applying TRIPM data poses greater challenges.This study presents the first attempt to use TRIPM data for retrieving solar extreme ultraviolet(EUV)flux.Our results demonstrate that by utilizing TRIPM data in regions where photoelectron excitation dominates as the primary radiation source,the solar EUV flux(denoted as Q_(EUV))can be retrieved.Comparisons with data from the SOHO/SEM instrument reveal excellent consistency,with a seasonal correlation coefficient(R)of at least 0.95.This work thus offers a new avenue for solar EUV flux acquisition and expands the application range of TRIPM data. 展开更多
关键词 N_(2)LBH band solar EUV THERMOSPHERE
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Evaluating climate-induced productivity of typical ecosystems of the eastern margin of the Qinghai-Tibet Plateau
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作者 ZHENG Huazhu YAO Zhengyu +6 位作者 LU Jungang WU Yongjiao YE Quan ZHAO Hongfei OUYANG Maolin Claudio ODELANG HE Hongming 《Journal of Geographical Sciences》 2026年第1期107-128,共22页
Ecosystems along the eastern margin of the Qinghai-Tibet Plateau(EQTP)are highly fragile and extremely sensitive to climate change and human disturbances.To quantitatively assess climate-induced ecosystem responses,th... Ecosystems along the eastern margin of the Qinghai-Tibet Plateau(EQTP)are highly fragile and extremely sensitive to climate change and human disturbances.To quantitatively assess climate-induced ecosystem responses,this study proposes a Climate-Induced Productivity Index(CIPI)based on the Super Slack-Based Measure(Super-SBM)model using remote sensing data from 2001 to 2020.The results reveal persistently low CIPI values(0.47-0.53)across major ecosystem types,indicating widespread vulnerability to climatic variability.Among these ecosystems,forests exhibit the highest CIPI(0.55),followed by shrublands(0.54),croplands(0.53),grasslands(0.51),and barelands(0.43).The Theil index analysis further demonstrates significant intra-group disparities,suggesting that extreme climatic events amplify CIPI heterogeneity.Moreover,the dominant environmental drivers differ among ecosystem types:the Palmer Drought Severity Index(PDSI)primarily constrains grassland productivity,solar radiation(SRAD)strongly influences shrub and cropland systems,whereas subsurface factors exert greater control in forested regions.This study provides a quantitative framework for evaluating climate-ecosystem interactions and offers a scientific basis for long-term ecological monitoring and security planning across the EQTP. 展开更多
关键词 climate-induced productivity index(CIPI) Super-SBM model ecosystem vulnerability environmental drivers eastern margin of Qinghai-Tibet Plateau
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Momentum transfer collision frequencies between electrons and neutrals of astrophysical interest
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作者 YuTian Cao Jun Cui +4 位作者 RuiQi Fu WenJun Liang XiaoShu Wu TieLong Zhang HaoYu Lu 《Earth and Planetary Physics》 2026年第1期82-91,共10页
Theoretical calculations serve as an effective method for determining plasma temperatures within planetary atmospheres.To simulate plasma temperature,a comprehensive implementation of the energy equation is used,which... Theoretical calculations serve as an effective method for determining plasma temperatures within planetary atmospheres.To simulate plasma temperature,a comprehensive implementation of the energy equation is used,which is governed by five terms:conductivity,heating,cooling,adiabatic expansion,and advection.The derivations mentioned are strongly dependent on the collision cross section between electrons and other particles(e.g.,neutrals,ions).It is notable that the momentum transfer cross sections between electrons and neutrals have been updated in recent decades.However,the widely used momentum average collision cross sections between electrons and neutrals,derived from the momentum transfer cross sections,are collected in studies dating back nearly half a century.Therefore,it becomes imperative to revise the momentum average collision cross sections relevant to astrophysical contexts,based on the latest studies.In this study,we summarize the momentum average collision cross sections of 13 species common in planetary atmospheres:H,H_(2),He,O,CH_(4),H_(2)O,CO,N_(2),O_(2),Ar,CO_(2),N_(2)O,and NO_(2).All results are derived from the latest studies concerning the electron-neutral collision cross section and are compared with previous studies.Furthermore,we present a comparison of the derived total electron-neutral collision frequency at Mars between this study and previous studies.Prominent differences in the total electron-neutral collision frequency between this and prior studies support the significance of updating the momentum average collision cross section between electrons and neutrals in studying the planetary atmospheres. 展开更多
关键词 momentum transfer collision planetary atmosphere electron-neutral collision frequency
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Taxonomic classification of 80 near-Earth asteroids
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作者 Fan Mo Bin Li +9 位作者 HaiBin Zhao Jian Chen Yan Jin MengHui Tang Igor Molotov A.M.Abdelaziz A.Takey S.K.Tealib Ahmed.Shokry JianYang Li 《Earth and Planetary Physics》 2026年第1期196-204,共9页
Near-Earth objects are important not only in studying the early formation of the Solar System,but also because they pose a serious hazard to humanity when they make close approaches to the Earth.Study of their physica... Near-Earth objects are important not only in studying the early formation of the Solar System,but also because they pose a serious hazard to humanity when they make close approaches to the Earth.Study of their physical properties can provide useful information on their origin,evolution,and hazard to human beings.However,it remains challenging to investigate small,newly discovered,near-Earth objects because of our limited observational window.This investigation seeks to determine the visible colors of near-Earth asteroids(NEAs),perform an initial taxonomic classification based on visible colors and analyze possible correlations between the distribution of taxonomic classification and asteroid size or orbital parameters.Observations were performed in the broadband BVRI Johnson−Cousins photometric system,applied to images from the Yaoan High Precision Telescope and the 1.88 m telescope at the Kottamia Astronomical Observatory.We present new photometric observations of 84 near-Earth asteroids,and classify 80 of them taxonomically,based on their photometric colors.We find that nearly half(46.3%)of the objects in our sample can be classified as S-complex,26.3%as C-complex,6%as D-complex,and 15.0%as X-complex;the remaining belong to the A-or V-types.Additionally,we identify three P-type NEAs in our sample,according to the Tholen scheme.The fractional abundances of the C/X-complex members with absolute magnitude H≥17.0 were more than twice as large as those with H<17.0.However,the fractions of C-and S-complex members with diameters≤1 km and>1 km are nearly equal,while X-complex members tend to have sub-kilometer diameters.In our sample,the C/D-complex objects are predominant among those with a Jovian Tisserand parameter of T_(J)<3.1.These bodies could have a cometary origin.C-and S-complex members account for a considerable proportion of the asteroids that are potentially hazardous. 展开更多
关键词 near-Earth asteroids optical telescope photometric observation taxonomic classification
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Tracing equatorward and poleward boundaries of the magnetospheric cusp from a simulated X-ray image
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作者 Xue Wang TianRan Sun +4 位作者 C.Philippe Escoubet Andy Read YiHong Guo Steve Sembay Chi Wang 《Earth and Planetary Physics》 2026年第1期144-155,共12页
A large-scale view of the magnetospheric cusp is expected to be obtained by the Soft X-ray Imager(SXI)onboard the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE).However,it is challenging to trace the three-d... A large-scale view of the magnetospheric cusp is expected to be obtained by the Soft X-ray Imager(SXI)onboard the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE).However,it is challenging to trace the three-dimensional cusp boundary from a two-dimensional X-ray image because the detected X-ray signals will be integrated along the line of sight.In this work,a global magnetohydrodynamic code was used to simulate the X-ray images and photon count images,assuming an interplanetary magnetic field with a pure Bz component.The assumption of an elliptic cusp boundary at a given altitude was used to trace the equatorward and poleward boundaries of the cusp from a simulated X-ray image.The average discrepancy was less than 0.1 RE.To reduce the influence of instrument effects and cosmic X-ray backgrounds,image denoising was considered before applying the method above to SXI photon count images.The cusp boundaries were reasonably reconstructed from the noisy X-ray image. 展开更多
关键词 SMILE mission X-ray image cusp boundary
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Machine learning in geosciences and remote sensing 被引量:45
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作者 David J.Lary Amir H.Alavi +1 位作者 Amir H.Gandomi Annette L.Walker 《Geoscience Frontiers》 SCIE CAS CSCD 2016年第1期3-10,共8页
Learning incorporates a broad range of complex procedures. Machine learning(ML) is a subdivision of artificial intelligence based on the biological learning process. The ML approach deals with the design of algorith... Learning incorporates a broad range of complex procedures. Machine learning(ML) is a subdivision of artificial intelligence based on the biological learning process. The ML approach deals with the design of algorithms to learn from machine readable data. ML covers main domains such as data mining, difficultto-program applications, and software applications. It is a collection of a variety of algorithms(e.g. neural networks, support vector machines, self-organizing map, decision trees, random forests, case-based reasoning, genetic programming, etc.) that can provide multivariate, nonlinear, nonparametric regression or classification. The modeling capabilities of the ML-based methods have resulted in their extensive applications in science and engineering. Herein, the role of ML as an effective approach for solving problems in geosciences and remote sensing will be highlighted. The unique features of some of the ML techniques will be outlined with a specific attention to genetic programming paradigm. Furthermore,nonparametric regression and classification illustrative examples are presented to demonstrate the efficiency of ML for tackling the geosciences and remote sensing problems. 展开更多
关键词 Machine learning GEOSCIENCES Remote sensing Regression CLASSIFICATION
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China's Planning for Deep Space Exploration and Lunar Exploration before 2030 被引量:12
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作者 XU Lin ZOU Yongliao JIA Yingzhuo 《空间科学学报》 CAS CSCD 北大核心 2018年第5期591-592,共2页
The current lunar exploration has changed from a single scientific exploration to science and resource utilization. On the basis of the previous lunar exploration, Chinese scientists and technical experts have propose... The current lunar exploration has changed from a single scientific exploration to science and resource utilization. On the basis of the previous lunar exploration, Chinese scientists and technical experts have proposed an overall plan to preliminarily build a lunar research station on the lunar South Pole by several missions before 2035, exploring of the moon, as well as the use of lunar platforms and in-site utilization of resources. In addition, China will also explore Mars, asteroids and Jupiter and its moons. This paper briefly introduces the ideas of Chinese scientists and technical experts on the lunar and deep space exploration. 展开更多
关键词 中国科学家 空间探索 月亮 探索计划 资源利用 科学探索 技术专家
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Advanced Space-based Solar Observatory(ASO-S):an overview 被引量:35
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作者 Wei-Qun Gan Cheng Zhu +37 位作者 Yuan-Yong Deng Hui Li Yang Su Hai-Ying Zhang Bo Chen Zhe Zhang Jian Wu Lei Deng Yu Huang Jian-Feng Yang Ji-Jun Cui Jin Chang Chi Wang Ji Wu Zeng-Shan Yin Wen Chen Cheng Fang Yi-Hua Yan Jun Lin Wei-Ming Xiong Bin Chen Hai-Chao Bao Cai-Xia Cao Yan-Ping Bai Tao Wang Bing-Long Chen Xin-Yu Li Ye Zhang Li Feng Jiang-Tao Su Ying Li Wei Chen You-Ping Li Ying-Na Su Hai-Yan Wu Mei Gu Lei Huang Xue-Jun Tang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2019年第11期3-10,共8页
The Advanced Space-based Solar Observatory(ASO-S)is a mission proposed for the 25 th solar maximum by the Chinese solar community.The scientific objectives are to study the relationships between the solar magnetic fie... The Advanced Space-based Solar Observatory(ASO-S)is a mission proposed for the 25 th solar maximum by the Chinese solar community.The scientific objectives are to study the relationships between the solar magnetic field,solar flares and coronal mass ejections(CMEs).Three payloads are deployed:the Full-disk vector Magneto Graph(FMG),the Lyman-αSolar Telescope(LST)and the Hard X-ray Imager(HXI).ASO-S will perform the first simultaneous observations of the photospheric vector magnetic field,non-thermal imaging of solar flares,and the initiation and early propagation of CMEs on a single platform.ASO-S is scheduled to be launched into a 720 km Sun-synchronous orbit in 2022.This paper presents an overview of the mission till the end of Phase-B and the beginning of Phase-C. 展开更多
关键词 space vehicles instruments-Sun magnetic fields-Sun flares-Sun CMEs-Sun UV radiation-Sun X-ray gamma-rays
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