The Beijing Spectrometer(BESIII)collaboration has reported the world’s first observation of the decay D+→τ+ν,which is the second type of pure leptonic decay of the D+meson,in a newly published Physical Review Lett...The Beijing Spectrometer(BESIII)collaboration has reported the world’s first observation of the decay D+→τ+ν,which is the second type of pure leptonic decay of the D+meson,in a newly published Physical Review Letters paper.The paper has been highlighted by the journal as an"Editors’Suggestion."展开更多
Mudslides buried and flooded hundreds of homes on Sunday, August 8, in Zhouqu,the Gannan Tibetan Autonomous Prefecture of northwest Gansu Province. The death toll from the massive rain-triggered mudslides in Zhouqu C...Mudslides buried and flooded hundreds of homes on Sunday, August 8, in Zhouqu,the Gannan Tibetan Autonomous Prefecture of northwest Gansu Province. The death toll from the massive rain-triggered mudslides in Zhouqu County had risen to 1,239 as of August 15, a week after the devastating mudslides hit the county, with 505 others still missing.展开更多
The objective of the current study is to investigate an adaptive predictive observer-based autopilot for a skid-to-turn(STT)missile model with uncertainties and unknown dynamic equations.A predictive control for the S...The objective of the current study is to investigate an adaptive predictive observer-based autopilot for a skid-to-turn(STT)missile model with uncertainties and unknown dynamic equations.A predictive control for the STT missile is designed based on nonlinear model predictive control(NMPC)using Taylor series expansion,after which,via a neural network(NN),unknown functions are approximated.The present study also evaluates an adaptive optimal observer of a new strategy-based nonlinear system.Specifically,to estimate the missile states such as normal acceleration and its derivatives for the future,originally the Taylor series states expansion was gained to any specified order,based on their receding horizons.To address the problem of prediction error,an analytic solution was prepared that led to a closed form regarding the nonlinear optimal observer.Out of the gains resulting from the analytic solution,as developed for the problem of prediction error,the selection of the proposed observer gain was optimally conducted to meet the stability condition.Thus,combining the adaptive predictive autopilot and the adaptive optimal observer scheme was implemented to secure the performance,which needed only estimated normal acceleration and its derivatives.Meanwhile,no angular velocity measurement or wind angle estimation was required.Ultimately,the proposed technique was found effective,as confirmed by the qualitative simulation results.展开更多
The Antarctic Tianmu Staring Observation Project(ATSOP)entails the deployment of 30 small-aperture,wide-field optical telescopes in the Antarctic region.The system will perform long-term continuous observation campaig...The Antarctic Tianmu Staring Observation Project(ATSOP)entails the deployment of 30 small-aperture,wide-field optical telescopes in the Antarctic region.The system will perform long-term continuous observation campaigns over a period of 100 d(24 h per day)per year,as well as short-time-scale sampling at intervals of 5 min,across a sky area of approximately 1200 square degrees centered near the south celestial pole.We have assessed the types of small solar system bodies detectable by the ATSOP telescopes,as well as the associated scientific research opportunities.Our analysis indicates that the ATSOP is capable of detecting near-Earth objects(NEOs)with all orbital inclinations,as well as high-inclination small bodies located beyond the main asteroid belt.Potential research topics include the discovery and identification of small bodies,orbit determination,physical characterization,investigation into the activity characteristics and evolutionary patterns of active small bodies,and studies on their dynamical evolution.Observations of NEOs can also contribute to planetary defense efforts.On the basis of pilot observational data collected by the Antarctic Tianmu prototype(AT-Proto)between February 20 and October 26,2023,a total of 478 asteroids and 9 comets were successfully identified,demonstrating the effectiveness of the ATSOP system in observing small solar system bodies.Looking ahead,with anticipated performance enhancements in the second-generation AT-Proto,the limiting magnitude will increase from 16 to 18,thereby enabling the detection of an even greater number of small solar system bodies.展开更多
This paper addresses the synchronization of follower agents’state vectors with that of a leader in high-order nonlinear multi-agent systems.The proposed low-complexity control scheme employs high-gain observers to es...This paper addresses the synchronization of follower agents’state vectors with that of a leader in high-order nonlinear multi-agent systems.The proposed low-complexity control scheme employs high-gain observers to estimate higher-order synchronization errors,enabling the controller to rely solely on relative output measurements.This approach significantly reduces the dependence on full-state information,which is often infeasible or costly in practical engineering applications.An output feedback control strategy is developed to overcome these limitations while ensuring robust and effective synchronization.Simulation results are provided to demonstrate the effectiveness of the proposed approach and validate the theoretical findings.展开更多
Climate change,natural disasters,pollution,and fast urbanization have made environmental security a more serious international issue.Timely,accurate,and multi-dimensional information is essential in the effective moni...Climate change,natural disasters,pollution,and fast urbanization have made environmental security a more serious international issue.Timely,accurate,and multi-dimensional information is essential in the effective monitoring and management of such complex challenges in the environment.The Earth Observation(EO)systems,including optical sensors,radar sensors,Light Detection and Ranging(LiDAR)sensors,thermal sensors,Unmanned Aerial Vehicle(UAV)sensors,and in-situ sensors,offer a good coverage of space and time,as well as provide useful information on land,water,and atmospheric processes.But the shortcomings or weaknesses of individual sensors,such as their vulnerability to weather conditions,spectral or spatial resolution,and gaps in time,can tend to limit their ability to provide a complete picture of the environment.One of the solutions has been multi-sensor fusion,which combines heterogeneous data and makes it more accurate,robust,and interpretable.This systematic review analyzes the latest methods of multi-sensor fusion,which are machine learning,deep learning,probabilistic models,and hybrid approaches,in terms of methodological principles,preprocessing needs,and computational frameworks.Applications in environmental security are highlighted,which include monitoring natural disasters,monitoring of climate and ecosystem,pollution monitoring,monitoring of land use change,and early warning systems.The review also covers evaluation measures,validation plans,and uncertainty measures,where a strict measure of evaluation is vital to making actionable decisions.Lastly,emerging issues,e.g.,data heterogeneity,computational needs,sensor interoperability,and prospects in the future,e.g.,AI-based adaptive fusion,UAVs and Internet of Things(IoT)integration,and scalable cloud-based systems,are discussed.The synthesis has highlighted the transformational capability of multi-sensor EO in terms of improving the environment in the context of environmental security and sustainable management.展开更多
Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and ...Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.展开更多
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
Software-defined,data-intensive cyber-physical systems and software-defined networks of atmospheric observers are evolving rapidly due to the rapid expansion of sensing diversity,the volume of streaming data,and the d...Software-defined,data-intensive cyber-physical systems and software-defined networks of atmospheric observers are evolving rapidly due to the rapid expansion of sensing diversity,the volume of streaming data,and the demand for low-latency,decision-relevant products.Simultaneously,artificial intelligence(AI)and the continuously evolving state of computing are making it possible to create end-to-end architecture fostering the migrations of the presumably single algorithm to combined intelligent ingestion,quality control,and multi-modal fusion,uncertainty-related retrieval,and scalable service delivery at the edge-to-cloud-high-performance computing(HPC)environment.This overview summarizes AI-based models of future atmospheric observation networks within a single,consolidated taxonomy based on deployment topology,learning and update modes,connectivity to physical models and data assimilation,level of autonomy(passive to adaptive sensing),and model of governance.Next,we consider recurring architectural themes,such as edge intelligence and streaming provenance and machine learning operations(MLOps)/model operations(ModelOps)to continue evaluation and safely update,and we scrutinize integration gateways with physical models,like data-assimilation-oriented outputs,hybrid/physics-informed designs,and simulation of observing systems using digital twins.Lastly,we address evaluation and readiness aspects that are not limited to predictive skill,but also involve calibrated uncertainty,nonstationary and extreme robustness,system latency and reliability,interoperability,security,and demonstrated downstream influence on analyses and forecasts.Through bringing together the cross-cutting issues and prospects,this review provides a road map with respect to trustworthy,interoperable,and sustainable observation infrastructures in which code and climate science will co-evolve.展开更多
Theintegration of human factors into artificial intelligence(AI)systems has emerged as a critical research frontier,particularly in reinforcement learning(RL),where human-AI interaction(HAII)presents both opportunitie...Theintegration of human factors into artificial intelligence(AI)systems has emerged as a critical research frontier,particularly in reinforcement learning(RL),where human-AI interaction(HAII)presents both opportunities and challenges.As RL continues to demonstrate remarkable success in model-free and partially observable environments,its real-world deployment increasingly requires effective collaboration with human operators and stakeholders.This article systematically examines HAII techniques in RL through both theoretical analysis and practical case studies.We establish a conceptual framework built upon three fundamental pillars of effective human-AI collaboration:computational trust modeling,system usability,and decision understandability.Our comprehensive review organizes HAII methods into five key categories:(1)learning from human feedback,including various shaping approaches;(2)learning from human demonstration through inverse RL and imitation learning;(3)shared autonomy architectures for dynamic control allocation;(4)human-in-the-loop querying strategies for active learning;and(5)explainable RL techniques for interpretable policy generation.Recent state-of-the-art works are critically reviewed,with particular emphasis on advances incorporating large language models in human-AI interaction research.To illustrate some concepts,we present three detailed case studies:an empirical trust model for farmers adopting AI-driven agricultural management systems,the implementation of ethical constraints in roboticmotion planning through human-guided RL,and an experimental investigation of human trust dynamics using a multi-armed bandit paradigm.These applications demonstrate how HAII principles can enhance RL systems’practical utility while bridging the gap between theoretical RL and real-world human-centered applications,ultimately contributing to more deployable and socially beneficial intelligent systems.展开更多
The threat posed by space debris to space security is continuously increasing.Optical observation is the main detection method for space debris,but the variety of observation geometries in available measurement datase...The threat posed by space debris to space security is continuously increasing.Optical observation is the main detection method for space debris,but the variety of observation geometries in available measurement datasets is limited.Therefore,simulations are required to supplement observational data.Hardware-in-the-loop(HIL)simulations can provide high-quality simulated optical detection data at a reasonable cost,but existing hardware-in-the-loop methods are only adapted to simple motion scenarios.To extend the simulation ability to complex space motion scenarios,here we propose an optical hardware-in-the-loop space debris simulation method,relying on dynamic detection scenarios,that uses a collaborative scenario-modality-feature simulation scheme to simulate variable observation geometries and to obtain sequential space debris simulation data covering a variety of modalities and scenarios.We apply the proposed space debris detection method to ground-based and space-based simulation experiments and analyze target features within the simulated detection data to demonstrate the usefulness of such simulations.Our simulation method is applicable to space debris optical detection under diverse observation conditions and to multidimensional space debris feature characterization.展开更多
This paper investigates the consensus tracking control problem for high order nonlinear multi-agent systems subject to non-affine faults,partial measurable states,uncertain control coefficients,and unknown external di...This paper investigates the consensus tracking control problem for high order nonlinear multi-agent systems subject to non-affine faults,partial measurable states,uncertain control coefficients,and unknown external disturbances.Under the directed topology conditions,an observer-based finite-time control strategy based on adaptive backstepping and is proposed,in which a neural network-based state observer is employed to approximate the unmeasurable system state variables.To address the complexity explosion problem associated with the backstepping method,a finite-time command filter is incorporated,with error compensation signals designed to mitigate the filter-induced errors.Additionally,the Butterworth low-pass filter is introduced to avoid the algebraic ring problem in the design of the controller.The finite-time stability of the closed-loop system is rigorously analyzed with the finite-time Lyapunov stability criterion,validating that all closed-loop signals of the system remain bounded within a finite time.Finally,the effectiveness of the proposed control strategy is verified through a simulation example.展开更多
Dual-polarization(dual-pol)radar variables provide information about the quantity,type,size,and water content of hydrometeors.Assimilating these dual-pol radar variables into numerical weather prediction models can en...Dual-polarization(dual-pol)radar variables provide information about the quantity,type,size,and water content of hydrometeors.Assimilating these dual-pol radar variables into numerical weather prediction models can enhance forecast accuracy.Observation operators are essential for radar data assimilation.This study focuses on applying a realistic dual-pol radar observation operator to more accurately calculate dual-pol radar variables.Previously reported dual-pol radar observation operators tended to overestimate radar variables near 0℃ in convective precipitation and simulate unrealistic dual-pol radar variables in subfreezing regions.To address this,the improved operator(KNU dual-pol radar observation operator;K-DROP)limits the distribution of mixed-phase hydrometeors,which have both solid and liquid properties,in areas with strong updrafts and downdrafts,improving the overestimation of radar variables near the melting layer.Additionally,by applying the observed snow axis ratio during winter to K-DROP,the issue of differential reflectivity(Z_(DR))being calculated as a constant value in subfreezing regions has been improved.By incorporating the observed maximum radius of hydrometeors into K-DROP,the overestimation of reflectivity(Z_(H))in subfreezing regions,the overestimation of Z_(DR)in warm regions,and the underestimation of specific differential phase(K_(DP))in subfreezing regions and overestimation in warm regions,are improved.Compared to previous operators,the enhanced version reported in the present work produces more realistic dual-pol radar variables.展开更多
State Field Observation and Research Station of Debris Flow in Dongchuan,Yunnan is also named Dongchuan Debris Flow Observation and Research Station,Chinese Academy of Sciences.The study area,Jiangjia Ravine,is about ...State Field Observation and Research Station of Debris Flow in Dongchuan,Yunnan is also named Dongchuan Debris Flow Observation and Research Station,Chinese Academy of Sciences.The study area,Jiangjia Ravine,is about 48.6 km2 and characterized by intense tectonism.Accumulated clastic detritus is the main source of the materials in the debris flows when an intense rainfall occurs.The recorded highest density and sediment transport are 2370 kg/m^(3) and 6.079×10^(6) kg/s,respectively.The ravine is now called the“debris flow museum”in China and supplies advantageous research conditions.展开更多
This paper investigates the detection and mitigation of coordinated cyberattacks on Load Frequency Control(LFC)systems integrated with Battery Energy Storage Systems(BESS).As renewable energy sources gain greater pene...This paper investigates the detection and mitigation of coordinated cyberattacks on Load Frequency Control(LFC)systems integrated with Battery Energy Storage Systems(BESS).As renewable energy sources gain greater penetration,power grids are becoming increasingly vulnerable to cyber threats,potentially leading to frequency instability and widespread disruptions.We model two significant attack vectors:load-altering attacks(LAAs)and false data injection attacks(FDIAs)that corrupt frequency measurements.These are analyzed for their impact on grid frequency stability in both linear and nonlinear LFC models,incorporating generation rate constraints and nonlinear loads.A coordinated attack strategy is presented,combining LAAs and FDIAs to achieve stealthiness by concealing frequency deviations from system operators,thereby maximizing disruption while evading traditional detection.To counteract these threats,we propose an Unknown Input Observer(UIO)-based detection framework for linear and nonlinear LFCs.The UIO is designed using linear matrix inequalities(LMIs)to estimate system states while isolating unknown attack inputs,enabling attack detection through monitoring measurement residuals against a predefined threshold.For mitigation,we leverage BESS capabilities with two adaptive strategies:dynamic mitigation for dynamic LAAs,which tunes BESS parameters to enhance the system’s stability margin and accelerate convergence to equilibrium;and staticmitigation for static LAAs and FDIAs.Simulations show that the UIO achieves high detection accuracy,with residuals exceeding thresholds promptly under coordinated attacks,even in nonlinear models.Mitigation strategies reduce frequency deviations by up to 80%compared to unmitigated cases,restoring stability within seconds.展开更多
Energy transfers among internal waves in the northern South China Sea are not well characterized,particularly during typhoons,owing to the lack of in situ observations.Based on high-resolution mooring data collected d...Energy transfers among internal waves in the northern South China Sea are not well characterized,particularly during typhoons,owing to the lack of in situ observations.Based on high-resolution mooring data collected during Typhoon Trami(2024),this study reveals the occurrence of robust vertical energy redistribution among diurnal internal tides(D1 ITs)and near-inertial waves(NIWs).Strikingly,the typhoon not only amplified the NIW energy but also triggered an unexpected surge in the D1 IT energy.The observed average net energy transfer rate of 1×10^(-7) W kg^(−1) from typhoon-forced NIWs to D1 ITs occurred at water depths of 120-170 m.Further bispectral analysis indicated that the energy transfer is driven by nonlinear wave—wave interaction.These results reveal the existence of a new energy transfer pathway—from atmospheric forcing to D1 ITs—and redefine the redistribution of the internal wave energy during extreme weather events.展开更多
We investigate the effects of projectile material on high-speed penetration/perforation of Inconel 718 alloy(IN718)plates.High-speed ballistic impact tests are conducted on 2 mm-thickness IN718 plates with 5-mm-diamet...We investigate the effects of projectile material on high-speed penetration/perforation of Inconel 718 alloy(IN718)plates.High-speed ballistic impact tests are conducted on 2 mm-thickness IN718 plates with 5-mm-diameter stainless steel 304(SS304),Ti alloy TC4,and Al alloy AA1060 spherical projectiles.The impact processes are captured with high-speed photography.Optical and scanning electron microscopy and laser scan are conducted on recovered projectiles and targets.Finite element models of the ballistic impact are established based on the coupled Eulerian-Lagrangian algorithm with the Johnson-Cook constitutive model and failure criterion,and can well reproduce the experimental results.The experimental and simulated data related to projectile dynamics,and the geometries of postmortem projectiles and bullet holes are analyzed with phenomenological models.Projectile velocity evolution can be described with hydrodynamic models of penetration.Dimensional analysis reveals a universal relationship between the bullet hole expansion coefficient and the normalized dynamic pressure,regardless of the projectile material.However,the projectile material does affect projectile deformation,bullet hole size,and energy absorption of target.展开更多
The Tibetan Plateau(TP),characterized by its elevated topography,plays a crucial role in regional environmental and climate dynamics,where the understanding of radiation energy budgets is essential.However,accurately ...The Tibetan Plateau(TP),characterized by its elevated topography,plays a crucial role in regional environmental and climate dynamics,where the understanding of radiation energy budgets is essential.However,accurately estimating the spatiotemporal variations of radiation budget components and surface albedo across the diverse landscapes of the TP remains a significant challenge for the scientific community.To address this issue,numerous atmospheric experiments and research initiatives have been conducted since the 1960s,focusing on quantitatively assessing the spatial distribution and temporal variations of radiation fluxes through both observational data and remote sensing techniques.This paper systematically reviews the key advancements in radiation energy studies over the past 35 years,with a particular focus on measurements derived from tens of radiation flux stations and satellite observations across the TP.Additionally,the development of parameterization schemes in topographical effects on radiation fluxes is also summarized.Finally,the paper discusses potential future research directions in this field.展开更多
Objective:To evaluate the clinical efficacy of blood-letting cupping combined with manual lymphatic drainage in treating breast cancer-related lymphedema(BCRL)and explore its mechanism of action from both traditional ...Objective:To evaluate the clinical efficacy of blood-letting cupping combined with manual lymphatic drainage in treating breast cancer-related lymphedema(BCRL)and explore its mechanism of action from both traditional Chinese medicine and modern medical perspectives,providing a scientific basis and novel therapeutic approaches for clinical management of BCRL.Methods:Patients with BCRL admitted to the outpatient and inpatient departments of Hebei University Affiliated Hospital were enrolled.A prospective randomized controlled trial design was adopted,with eligible patients randomly assigned to a treatment group and a control group.The control group received manual lymphatic drainage alone,while the treatment group received manual lymphtic drainage combined with blood-letting cupping therapy.Posttreatment comparisons evaluated upper limb circumference reduction,edema severity grading,and upper limb functional scores.Vital signs and adverse reactions during treatment were recorded for both groups.Statistical software analyzed the data.Results:The treatment group demonstrated significantly greater reduction in upper limb circumference,improvement in edema severity,and higher upper limb function scores compared to the control group(P<0.05).Vital signs remained stable throughout treatment in both groups.No severe adverse reactions occurred in the treatment group;only isolated cases of mild skin itching were reported,which resolved after symptomatic management.Conclusion:The combination of bloodletting cupping and manual lymphatic drainage demonstrates reliable efficacy in treating BCRL,effectively alleviating edema symptoms and improving upper limb function with high safety.Its mechanism may relate to traditional Chinese medicine principles of“unblocking meridians,promoting blood circulation,and resolving stasis”and modern medical concepts of“enhancing local blood circulation,facilitating lymphatic drainage,and reducing inflammatory responses”.展开更多
Here we report on simultaneous lidar observations of sporadic Ni(Nis)layers and sporadic Na(Nas)layers in the atmosphere over Yanqing,Beijing(40.42°N,116.02°E)from April 2019 to October 2022.During 343 night...Here we report on simultaneous lidar observations of sporadic Ni(Nis)layers and sporadic Na(Nas)layers in the atmosphere over Yanqing,Beijing(40.42°N,116.02°E)from April 2019 to October 2022.During 343 nights of observation,68 Nis and 56 Nas were observed.The seasonal variation of Nis and Nas was also obtained,with the highest occurrence of Nis being in July(43%)and that of Nas being in June(61%).We found that the seasonal variation of Nis is similar to that of Nas and that both occur more frequently in summer than in winter.In addition,we found 23 events in which Nis and Nas occur simultaneously.The average peak altitude of Nas is approximately 1 km higher than that of Nis,and the peak density ratio of Nas to Nis is approximately 5,which is half the density ratio of the two main layers.Additionally,the strength factor for Nas is smaller than that for Nis.Through data analysis of sporadic E layers(Es),we found that Nis and Nas has a significant correlation with Es.The neutralization rates of Ni^(+)/Na^(+)were calculated according to the dissociative recombination reaction of Ni^(+)/Na^(+)and the WACCM-Ni(Whole Atmosphere Community Climate Model of Ni).The production rates of Ni and Na were estimated to be approximately 1:4.4,which is consistent with the density ratio of Nis to Nas.The results showed that the neutralization reaction of Ni+,Na+,and electrons in Es is the main reason for the formation of the Nis layer and the Nas layer.展开更多
文摘The Beijing Spectrometer(BESIII)collaboration has reported the world’s first observation of the decay D+→τ+ν,which is the second type of pure leptonic decay of the D+meson,in a newly published Physical Review Letters paper.The paper has been highlighted by the journal as an"Editors’Suggestion."
文摘Mudslides buried and flooded hundreds of homes on Sunday, August 8, in Zhouqu,the Gannan Tibetan Autonomous Prefecture of northwest Gansu Province. The death toll from the massive rain-triggered mudslides in Zhouqu County had risen to 1,239 as of August 15, a week after the devastating mudslides hit the county, with 505 others still missing.
文摘The objective of the current study is to investigate an adaptive predictive observer-based autopilot for a skid-to-turn(STT)missile model with uncertainties and unknown dynamic equations.A predictive control for the STT missile is designed based on nonlinear model predictive control(NMPC)using Taylor series expansion,after which,via a neural network(NN),unknown functions are approximated.The present study also evaluates an adaptive optimal observer of a new strategy-based nonlinear system.Specifically,to estimate the missile states such as normal acceleration and its derivatives for the future,originally the Taylor series states expansion was gained to any specified order,based on their receding horizons.To address the problem of prediction error,an analytic solution was prepared that led to a closed form regarding the nonlinear optimal observer.Out of the gains resulting from the analytic solution,as developed for the problem of prediction error,the selection of the proposed observer gain was optimally conducted to meet the stability condition.Thus,combining the adaptive predictive autopilot and the adaptive optimal observer scheme was implemented to secure the performance,which needed only estimated normal acceleration and its derivatives.Meanwhile,no angular velocity measurement or wind angle estimation was required.Ultimately,the proposed technique was found effective,as confirmed by the qualitative simulation results.
基金supported by the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted by the Ministry of Finance of China(MOF)and administered by the Chinese Academy of Sciences(CAS),the National Natural Science Foundation of China(Nos.12173093 and 11973094)a science research grant from the China Manned Space Project(No.CMS-CSST-2021-B08).
文摘The Antarctic Tianmu Staring Observation Project(ATSOP)entails the deployment of 30 small-aperture,wide-field optical telescopes in the Antarctic region.The system will perform long-term continuous observation campaigns over a period of 100 d(24 h per day)per year,as well as short-time-scale sampling at intervals of 5 min,across a sky area of approximately 1200 square degrees centered near the south celestial pole.We have assessed the types of small solar system bodies detectable by the ATSOP telescopes,as well as the associated scientific research opportunities.Our analysis indicates that the ATSOP is capable of detecting near-Earth objects(NEOs)with all orbital inclinations,as well as high-inclination small bodies located beyond the main asteroid belt.Potential research topics include the discovery and identification of small bodies,orbit determination,physical characterization,investigation into the activity characteristics and evolutionary patterns of active small bodies,and studies on their dynamical evolution.Observations of NEOs can also contribute to planetary defense efforts.On the basis of pilot observational data collected by the Antarctic Tianmu prototype(AT-Proto)between February 20 and October 26,2023,a total of 478 asteroids and 9 comets were successfully identified,demonstrating the effectiveness of the ATSOP system in observing small solar system bodies.Looking ahead,with anticipated performance enhancements in the second-generation AT-Proto,the limiting magnitude will increase from 16 to 18,thereby enabling the detection of an even greater number of small solar system bodies.
文摘This paper addresses the synchronization of follower agents’state vectors with that of a leader in high-order nonlinear multi-agent systems.The proposed low-complexity control scheme employs high-gain observers to estimate higher-order synchronization errors,enabling the controller to rely solely on relative output measurements.This approach significantly reduces the dependence on full-state information,which is often infeasible or costly in practical engineering applications.An output feedback control strategy is developed to overcome these limitations while ensuring robust and effective synchronization.Simulation results are provided to demonstrate the effectiveness of the proposed approach and validate the theoretical findings.
文摘Climate change,natural disasters,pollution,and fast urbanization have made environmental security a more serious international issue.Timely,accurate,and multi-dimensional information is essential in the effective monitoring and management of such complex challenges in the environment.The Earth Observation(EO)systems,including optical sensors,radar sensors,Light Detection and Ranging(LiDAR)sensors,thermal sensors,Unmanned Aerial Vehicle(UAV)sensors,and in-situ sensors,offer a good coverage of space and time,as well as provide useful information on land,water,and atmospheric processes.But the shortcomings or weaknesses of individual sensors,such as their vulnerability to weather conditions,spectral or spatial resolution,and gaps in time,can tend to limit their ability to provide a complete picture of the environment.One of the solutions has been multi-sensor fusion,which combines heterogeneous data and makes it more accurate,robust,and interpretable.This systematic review analyzes the latest methods of multi-sensor fusion,which are machine learning,deep learning,probabilistic models,and hybrid approaches,in terms of methodological principles,preprocessing needs,and computational frameworks.Applications in environmental security are highlighted,which include monitoring natural disasters,monitoring of climate and ecosystem,pollution monitoring,monitoring of land use change,and early warning systems.The review also covers evaluation measures,validation plans,and uncertainty measures,where a strict measure of evaluation is vital to making actionable decisions.Lastly,emerging issues,e.g.,data heterogeneity,computational needs,sensor interoperability,and prospects in the future,e.g.,AI-based adaptive fusion,UAVs and Internet of Things(IoT)integration,and scalable cloud-based systems,are discussed.The synthesis has highlighted the transformational capability of multi-sensor EO in terms of improving the environment in the context of environmental security and sustainable management.
基金supported by the National Natural Science Foundation of China(Grant Nos.42027804,41775026,and 41075012)。
文摘Cirrus clouds play a crucial role in the energy balance of the Earth-atmosphere system.We investigated the spatiotemporal variations of cirrus over the South China Sea(SCS)using satellite data(MOD08,MYD08,CALIPSO)and reanalysis data(MERRA-2)from March 2007 to February 2015(eight years).The horizontal distribution reveals lower cirrus fraction values in the northern SCS and higher values in the southern region,with minima observed in March and April and maxima sequentially occurring in August(northern SCS,NSCS),September(middle SCS,MSCS),and December(southern SCS,SSCS).Vertically,the cirrus fraction peaks in summer and reaches its lowest levels in spring.Opaque cirrus dominates during summer in the NSCS and MSCS,comprising 53.6%and 55.9%,respectively,while the SSCS exhibits a higher frequency of opaque cirrus relative to other cloud types.Subvisible cirrus clouds have the lowest frequency year-round,whereas thin cirrus is most prominent in winter in the NSCS(46.3%)and in spring in the MSCS(45.3%).A case study from September 2021 further explores the influence of ice crystal habits on brightness temperature(BT)over the SCS.Simulations utilizing five ice crystal shapes from the ARTS DDA(Atmospheric Radiative Transfer Simulator Discrete Dipole Approximation)database and the RTTOV 12.4 radiative transfer model reveal that the 8-column-aggregate shape best represents BT in the NSCS and SSCS,while the large-block-aggregate shape performs better in the SSCS.
基金funded by the China National Space Administration(KJSP2023020105)supported by the National Key R&D Program of China(Grant No.2023YFA1608100)+2 种基金the NSFC(Grant No.62227901)the Minor Planet Foundationsupported by the Egyptian Science,Technology&Innovation Funding Authority(STDF)under Grant No.48102.
文摘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.
文摘Software-defined,data-intensive cyber-physical systems and software-defined networks of atmospheric observers are evolving rapidly due to the rapid expansion of sensing diversity,the volume of streaming data,and the demand for low-latency,decision-relevant products.Simultaneously,artificial intelligence(AI)and the continuously evolving state of computing are making it possible to create end-to-end architecture fostering the migrations of the presumably single algorithm to combined intelligent ingestion,quality control,and multi-modal fusion,uncertainty-related retrieval,and scalable service delivery at the edge-to-cloud-high-performance computing(HPC)environment.This overview summarizes AI-based models of future atmospheric observation networks within a single,consolidated taxonomy based on deployment topology,learning and update modes,connectivity to physical models and data assimilation,level of autonomy(passive to adaptive sensing),and model of governance.Next,we consider recurring architectural themes,such as edge intelligence and streaming provenance and machine learning operations(MLOps)/model operations(ModelOps)to continue evaluation and safely update,and we scrutinize integration gateways with physical models,like data-assimilation-oriented outputs,hybrid/physics-informed designs,and simulation of observing systems using digital twins.Lastly,we address evaluation and readiness aspects that are not limited to predictive skill,but also involve calibrated uncertainty,nonstationary and extreme robustness,system latency and reliability,interoperability,security,and demonstrated downstream influence on analyses and forecasts.Through bringing together the cross-cutting issues and prospects,this review provides a road map with respect to trustworthy,interoperable,and sustainable observation infrastructures in which code and climate science will co-evolve.
基金funded by the U.S.Department of Education under Grant Number ED#P116S210005the National Science Foundation under Grant Numbers 2226936 and 2420405.
文摘Theintegration of human factors into artificial intelligence(AI)systems has emerged as a critical research frontier,particularly in reinforcement learning(RL),where human-AI interaction(HAII)presents both opportunities and challenges.As RL continues to demonstrate remarkable success in model-free and partially observable environments,its real-world deployment increasingly requires effective collaboration with human operators and stakeholders.This article systematically examines HAII techniques in RL through both theoretical analysis and practical case studies.We establish a conceptual framework built upon three fundamental pillars of effective human-AI collaboration:computational trust modeling,system usability,and decision understandability.Our comprehensive review organizes HAII methods into five key categories:(1)learning from human feedback,including various shaping approaches;(2)learning from human demonstration through inverse RL and imitation learning;(3)shared autonomy architectures for dynamic control allocation;(4)human-in-the-loop querying strategies for active learning;and(5)explainable RL techniques for interpretable policy generation.Recent state-of-the-art works are critically reviewed,with particular emphasis on advances incorporating large language models in human-AI interaction research.To illustrate some concepts,we present three detailed case studies:an empirical trust model for farmers adopting AI-driven agricultural management systems,the implementation of ethical constraints in roboticmotion planning through human-guided RL,and an experimental investigation of human trust dynamics using a multi-armed bandit paradigm.These applications demonstrate how HAII principles can enhance RL systems’practical utility while bridging the gap between theoretical RL and real-world human-centered applications,ultimately contributing to more deployable and socially beneficial intelligent systems.
基金supported by the Special funding project for space debris and Near-Earth Asteroids defense research(KJSP2023020202).
文摘The threat posed by space debris to space security is continuously increasing.Optical observation is the main detection method for space debris,but the variety of observation geometries in available measurement datasets is limited.Therefore,simulations are required to supplement observational data.Hardware-in-the-loop(HIL)simulations can provide high-quality simulated optical detection data at a reasonable cost,but existing hardware-in-the-loop methods are only adapted to simple motion scenarios.To extend the simulation ability to complex space motion scenarios,here we propose an optical hardware-in-the-loop space debris simulation method,relying on dynamic detection scenarios,that uses a collaborative scenario-modality-feature simulation scheme to simulate variable observation geometries and to obtain sequential space debris simulation data covering a variety of modalities and scenarios.We apply the proposed space debris detection method to ground-based and space-based simulation experiments and analyze target features within the simulated detection data to demonstrate the usefulness of such simulations.Our simulation method is applicable to space debris optical detection under diverse observation conditions and to multidimensional space debris feature characterization.
基金supported in part by the Beijing Natural Science Foundation under Grant 4252050in part by the National Science Fund for Distinguished Young Scholars under Grant 62425304in part by the Basic Science Center Programs of NSFC under Grant 62088101.
文摘This paper investigates the consensus tracking control problem for high order nonlinear multi-agent systems subject to non-affine faults,partial measurable states,uncertain control coefficients,and unknown external disturbances.Under the directed topology conditions,an observer-based finite-time control strategy based on adaptive backstepping and is proposed,in which a neural network-based state observer is employed to approximate the unmeasurable system state variables.To address the complexity explosion problem associated with the backstepping method,a finite-time command filter is incorporated,with error compensation signals designed to mitigate the filter-induced errors.Additionally,the Butterworth low-pass filter is introduced to avoid the algebraic ring problem in the design of the controller.The finite-time stability of the closed-loop system is rigorously analyzed with the finite-time Lyapunov stability criterion,validating that all closed-loop signals of the system remain bounded within a finite time.Finally,the effectiveness of the proposed control strategy is verified through a simulation example.
基金supported by the National Research Foundation(NRF)funded by the Korean government(MSIT)(Grant Nos.2022R1A2C1012361,2022R1A6A3A 13073165 and RS-2025-02242970).
文摘Dual-polarization(dual-pol)radar variables provide information about the quantity,type,size,and water content of hydrometeors.Assimilating these dual-pol radar variables into numerical weather prediction models can enhance forecast accuracy.Observation operators are essential for radar data assimilation.This study focuses on applying a realistic dual-pol radar observation operator to more accurately calculate dual-pol radar variables.Previously reported dual-pol radar observation operators tended to overestimate radar variables near 0℃ in convective precipitation and simulate unrealistic dual-pol radar variables in subfreezing regions.To address this,the improved operator(KNU dual-pol radar observation operator;K-DROP)limits the distribution of mixed-phase hydrometeors,which have both solid and liquid properties,in areas with strong updrafts and downdrafts,improving the overestimation of radar variables near the melting layer.Additionally,by applying the observed snow axis ratio during winter to K-DROP,the issue of differential reflectivity(Z_(DR))being calculated as a constant value in subfreezing regions has been improved.By incorporating the observed maximum radius of hydrometeors into K-DROP,the overestimation of reflectivity(Z_(H))in subfreezing regions,the overestimation of Z_(DR)in warm regions,and the underestimation of specific differential phase(K_(DP))in subfreezing regions and overestimation in warm regions,are improved.Compared to previous operators,the enhanced version reported in the present work produces more realistic dual-pol radar variables.
文摘State Field Observation and Research Station of Debris Flow in Dongchuan,Yunnan is also named Dongchuan Debris Flow Observation and Research Station,Chinese Academy of Sciences.The study area,Jiangjia Ravine,is about 48.6 km2 and characterized by intense tectonism.Accumulated clastic detritus is the main source of the materials in the debris flows when an intense rainfall occurs.The recorded highest density and sediment transport are 2370 kg/m^(3) and 6.079×10^(6) kg/s,respectively.The ravine is now called the“debris flow museum”in China and supplies advantageous research conditions.
基金supported by the Natural Science Foundation of China No.62303126the project Major Scientific and Technological Special Project of Guizhou Province([2024]014).
文摘This paper investigates the detection and mitigation of coordinated cyberattacks on Load Frequency Control(LFC)systems integrated with Battery Energy Storage Systems(BESS).As renewable energy sources gain greater penetration,power grids are becoming increasingly vulnerable to cyber threats,potentially leading to frequency instability and widespread disruptions.We model two significant attack vectors:load-altering attacks(LAAs)and false data injection attacks(FDIAs)that corrupt frequency measurements.These are analyzed for their impact on grid frequency stability in both linear and nonlinear LFC models,incorporating generation rate constraints and nonlinear loads.A coordinated attack strategy is presented,combining LAAs and FDIAs to achieve stealthiness by concealing frequency deviations from system operators,thereby maximizing disruption while evading traditional detection.To counteract these threats,we propose an Unknown Input Observer(UIO)-based detection framework for linear and nonlinear LFCs.The UIO is designed using linear matrix inequalities(LMIs)to estimate system states while isolating unknown attack inputs,enabling attack detection through monitoring measurement residuals against a predefined threshold.For mitigation,we leverage BESS capabilities with two adaptive strategies:dynamic mitigation for dynamic LAAs,which tunes BESS parameters to enhance the system’s stability margin and accelerate convergence to equilibrium;and staticmitigation for static LAAs and FDIAs.Simulations show that the UIO achieves high detection accuracy,with residuals exceeding thresholds promptly under coordinated attacks,even in nonlinear models.Mitigation strategies reduce frequency deviations by up to 80%compared to unmitigated cases,restoring stability within seconds.
基金supported by the National Key R&D Plan Program of China [Grant number 2021YFC3101500]the National Natural Science Foundation of China [Grant number 42305014,42506024]。
文摘Energy transfers among internal waves in the northern South China Sea are not well characterized,particularly during typhoons,owing to the lack of in situ observations.Based on high-resolution mooring data collected during Typhoon Trami(2024),this study reveals the occurrence of robust vertical energy redistribution among diurnal internal tides(D1 ITs)and near-inertial waves(NIWs).Strikingly,the typhoon not only amplified the NIW energy but also triggered an unexpected surge in the D1 IT energy.The observed average net energy transfer rate of 1×10^(-7) W kg^(−1) from typhoon-forced NIWs to D1 ITs occurred at water depths of 120-170 m.Further bispectral analysis indicated that the energy transfer is driven by nonlinear wave—wave interaction.These results reveal the existence of a new energy transfer pathway—from atmospheric forcing to D1 ITs—and redefine the redistribution of the internal wave energy during extreme weather events.
基金supported by National Natural Science Foundation of China(No.12402465)Sichuan Science and Technology Program(No.2023NSFSC1284)。
文摘We investigate the effects of projectile material on high-speed penetration/perforation of Inconel 718 alloy(IN718)plates.High-speed ballistic impact tests are conducted on 2 mm-thickness IN718 plates with 5-mm-diameter stainless steel 304(SS304),Ti alloy TC4,and Al alloy AA1060 spherical projectiles.The impact processes are captured with high-speed photography.Optical and scanning electron microscopy and laser scan are conducted on recovered projectiles and targets.Finite element models of the ballistic impact are established based on the coupled Eulerian-Lagrangian algorithm with the Johnson-Cook constitutive model and failure criterion,and can well reproduce the experimental results.The experimental and simulated data related to projectile dynamics,and the geometries of postmortem projectiles and bullet holes are analyzed with phenomenological models.Projectile velocity evolution can be described with hydrodynamic models of penetration.Dimensional analysis reveals a universal relationship between the bullet hole expansion coefficient and the normalized dynamic pressure,regardless of the projectile material.However,the projectile material does affect projectile deformation,bullet hole size,and energy absorption of target.
基金supported by the National Natural Science Foundation of China(Grant Nos.42230610 and U2442213)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2022069)。
文摘The Tibetan Plateau(TP),characterized by its elevated topography,plays a crucial role in regional environmental and climate dynamics,where the understanding of radiation energy budgets is essential.However,accurately estimating the spatiotemporal variations of radiation budget components and surface albedo across the diverse landscapes of the TP remains a significant challenge for the scientific community.To address this issue,numerous atmospheric experiments and research initiatives have been conducted since the 1960s,focusing on quantitatively assessing the spatial distribution and temporal variations of radiation fluxes through both observational data and remote sensing techniques.This paper systematically reviews the key advancements in radiation energy studies over the past 35 years,with a particular focus on measurements derived from tens of radiation flux stations and satellite observations across the TP.Additionally,the development of parameterization schemes in topographical effects on radiation fluxes is also summarized.Finally,the paper discusses potential future research directions in this field.
文摘Objective:To evaluate the clinical efficacy of blood-letting cupping combined with manual lymphatic drainage in treating breast cancer-related lymphedema(BCRL)and explore its mechanism of action from both traditional Chinese medicine and modern medical perspectives,providing a scientific basis and novel therapeutic approaches for clinical management of BCRL.Methods:Patients with BCRL admitted to the outpatient and inpatient departments of Hebei University Affiliated Hospital were enrolled.A prospective randomized controlled trial design was adopted,with eligible patients randomly assigned to a treatment group and a control group.The control group received manual lymphatic drainage alone,while the treatment group received manual lymphtic drainage combined with blood-letting cupping therapy.Posttreatment comparisons evaluated upper limb circumference reduction,edema severity grading,and upper limb functional scores.Vital signs and adverse reactions during treatment were recorded for both groups.Statistical software analyzed the data.Results:The treatment group demonstrated significantly greater reduction in upper limb circumference,improvement in edema severity,and higher upper limb function scores compared to the control group(P<0.05).Vital signs remained stable throughout treatment in both groups.No severe adverse reactions occurred in the treatment group;only isolated cases of mild skin itching were reported,which resolved after symptomatic management.Conclusion:The combination of bloodletting cupping and manual lymphatic drainage demonstrates reliable efficacy in treating BCRL,effectively alleviating edema symptoms and improving upper limb function with high safety.Its mechanism may relate to traditional Chinese medicine principles of“unblocking meridians,promoting blood circulation,and resolving stasis”and modern medical concepts of“enhancing local blood circulation,facilitating lymphatic drainage,and reducing inflammatory responses”.
基金supported by the Specialized Research Fund for State Key Laboratories,Chinese Meridian Project,the Specialized Research Fund for the State Key Laboratory of Solar Activity and Space Weather,postgraduate Education Reform and Quality Improvement Project of Henan Province(Grant No.YJS2024JD32)Natural Science Foundation Project of Henan Province(Grant No.242300420253)National Natural Science Foundation of China for Young Scientists(Grant No.42504156)funding.
文摘Here we report on simultaneous lidar observations of sporadic Ni(Nis)layers and sporadic Na(Nas)layers in the atmosphere over Yanqing,Beijing(40.42°N,116.02°E)from April 2019 to October 2022.During 343 nights of observation,68 Nis and 56 Nas were observed.The seasonal variation of Nis and Nas was also obtained,with the highest occurrence of Nis being in July(43%)and that of Nas being in June(61%).We found that the seasonal variation of Nis is similar to that of Nas and that both occur more frequently in summer than in winter.In addition,we found 23 events in which Nis and Nas occur simultaneously.The average peak altitude of Nas is approximately 1 km higher than that of Nis,and the peak density ratio of Nas to Nis is approximately 5,which is half the density ratio of the two main layers.Additionally,the strength factor for Nas is smaller than that for Nis.Through data analysis of sporadic E layers(Es),we found that Nis and Nas has a significant correlation with Es.The neutralization rates of Ni^(+)/Na^(+)were calculated according to the dissociative recombination reaction of Ni^(+)/Na^(+)and the WACCM-Ni(Whole Atmosphere Community Climate Model of Ni).The production rates of Ni and Na were estimated to be approximately 1:4.4,which is consistent with the density ratio of Nis to Nas.The results showed that the neutralization reaction of Ni+,Na+,and electrons in Es is the main reason for the formation of the Nis layer and the Nas layer.
