Sporadic E(Es)layers in the ionosphere are characterized by intense plasma irregularities in the E region at altitudes of 90-130 km.Because they can significantly influence radio communications and navigation systems,...Sporadic E(Es)layers in the ionosphere are characterized by intense plasma irregularities in the E region at altitudes of 90-130 km.Because they can significantly influence radio communications and navigation systems,accurate forecasting of Es layers is crucial for ensuring the precision and dependability of navigation satellite systems.In this study,we present Es predictions made by an empirical model and by a deep learning model,and analyze their differences comprehensively by comparing the model predictions to satellite RO measurements and ground-based ionosonde observations.The deep learning model exhibited significantly better performance,as indicated by its high coefficient of correlation(r=0.87)with RO observations and predictions,than did the empirical model(r=0.53).This study highlights the importance of integrating artificial intelligence technology into ionosphere modelling generally,and into predicting Es layer occurrences and characteristics,in particular.展开更多
The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sh...The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sheet.The ions were demagnetized inside the electron current layer,but the electrons were still frozen in with the magnetic field line.Thus,this decoupling of ions and electrons gave rise to a strong Hall electric field,which could be the reason for the formation of the embedded thin current layer.The magnetized electrons,the absence of the nongyrotropic electron distribution,and negligible energy dissipation in the layer indicate that magnetic reconnection had not been triggered within the embedded thin current layer.The highly asymmetric plasma on the two sides of the current layer and low magnetic shear across it could suppress magnetic reconnection.The observations indicate that the embedded electric current layer,probably generated by the Hall electric field,even down to electron scale,is not a sufficient condition for magnetic reconnection.展开更多
To investigate the stable chromium(Cr)isotope variations during melt percolation in the mantle,we ana-lyzed the Cr isotopic compositions of fresh ultramafic rocks from the Balmuccia and Baldissero peridotite massifs l...To investigate the stable chromium(Cr)isotope variations during melt percolation in the mantle,we ana-lyzed the Cr isotopic compositions of fresh ultramafic rocks from the Balmuccia and Baldissero peridotite massifs located in the Italian Alps.These massifs represent fragments of the subcontinental lithospheric mantle.The samples collected included lherzolites,harzburgites,dunites,and pyroxenites.Lherzolites,formed through 5%-15%fractional melting of a primitive mantle source,exhibited δ^(53)Crvalues ranging from−0.13‰±0.03‰to−0.03‰±0.03‰.These values correlated negatively with Al_(2)O_(3)content,sug-gesting that partial melting induces Cr isotopic fractionation between the melts and residual peridotites.Harzburgites and dunites,influenced by the silicate melt percolation,displayed distinctδ^(53)Cr values.Notably,dunites not spatially associated with the pyroxenite veins exhibited slightly elevatedδ^(53)Cr val-ues(−0.05‰±0.03‰to 0.10‰±0.03‰)relative to lherzolites.This difference likely resulted from pyroxene dissolution and olivine precipitation during melt percolation processes.However,one dunite sample in direct contact with pyroxenite veins showed lowerδ^(53)Cr values(−0.26‰±0.03‰),possibly owing to the kinetic effects during silicate melt percolation.Pyroxenites are formed through the interac-tion of basaltic melts with the surrounding peridotite via a metasomatic reaction or crystallization in a vein.Most of theirδ^(53)Cr values(−0.26‰±0.03‰to−0.13‰±0.03‰)are positively correlated with MgO contents,suggesting that they were influenced by magmatic differentiation.However,two subsam-ples from a single clinopyroxenite vein exhibit anomalously lowδ^(53)Crvalues(−0.30‰±0.03‰and−0.43‰±0.03‰),which are attributed to kinetic isotopic fractionation during melt-percolation pro-cesses.Our findings suggest that melt percolation processes in the mantle contribute to the Cr isotopic heterogeneity observed within the Earth’s mantle.展开更多
Asteroids and comets,which have long been of interest to astronomers,are important components of the solar system.They contain rich primitive information about the early solar system,which provide a unique pathway for...Asteroids and comets,which have long been of interest to astronomers,are important components of the solar system.They contain rich primitive information about the early solar system,which provide a unique pathway for studying the formation and evolution of the solar system,and even the origin of life on planet Earth.In this review,the formation,evolution processes and the internal characteristics of the asteroids and comets in the solar system are presented.The focus of this review is on the internal characteristics especially the dielectric properties of asteroids and comets by radar observations.On this basis,the possible internal structure of these celestial bodies is discussed.Combined with the existing theories,simulations and experiments,the possible internal structure of near-Earth asteroid 2016 HO_(3) is a monolith while structure of active asteroid 311P/PANSTARRS remains unknown.In 2025,China will launch Tianwen-2 asteroid-comet exploration mission to detect 2016 HO_(3) and 311P/PANSTARRS,which will carry a penetrating radar to observe the internal characteristics of these two objects.展开更多
Atmospheric escape plays a critical role in shaping the long-term climate evolution of Mars.Among the various escape mechanisms,energetic neutral atoms(ENAs)generated through charge exchange between solar wind ions an...Atmospheric escape plays a critical role in shaping the long-term climate evolution of Mars.Among the various escape mechanisms,energetic neutral atoms(ENAs)generated through charge exchange between solar wind ions and exospheric neutrals serve as an important diagnostic for ion-neutral interactions and upper atmospheric loss.This study presents direct observations of hydrogen ENAs(H-ENAs)on the dayside of Mars by using the Mars Ion and Neutral Particle Analyzer(MINPA)onboard China’s Tianwen-1 orbiter.By analyzing H-ENA data during a coronal mass ejection and a stream interaction region from December 29,2021,to January 1,2022,and comparing these data with MAVEN/SWIA(Mars Atmosphere and Volatile EvolutioN/Solar Wind Ion Analyzer)solar wind measurements,we examine the temporal evolution of H-ENA flux and the associated sputtered escape of atmospheric constituents.The observed H-ENA velocity is consistent with upstream solar wind ions,and the H-ENA-to-ion intensity ratio is used to infer variations in exospheric density,revealing a delayed response to enhanced solar wind activity.Penetrating H-ENA intensities reach up to 5.3×10^(6)s^(−1) cm^(−2),with energy fluxes on the order of(0.5-8.1)×10^(−3) mW/m^(2).The estimated oxygen sputtered escape rate driven by penetrating H-ENAs ranges from 5.5×10^(23)s^(−1) to 5.2×10^(24)s^(−1),comparable to or exceeding previous estimates based on penetrating ions.The findings highlight the need for low-altitude H-ENA observations to better quantify their atmospheric interactions and refine our understanding of nonthermal escape processes at Mars.展开更多
The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)is a joint mission of the European Space Agency(ESA)and the Chinese Academy of Sciences(CAS).Primary goals are investigating the dynamic response of the Eart...The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)is a joint mission of the European Space Agency(ESA)and the Chinese Academy of Sciences(CAS).Primary goals are investigating the dynamic response of the Earth's magnetosphere to the solar wind(SW)impact via simultaneous in situ magnetosheath plasma and magnetic field measurements,X-Ray images of the magnetosheath and magnetic cusps,and UV images of global auroral distributions.Magnetopause deformations associated with magnetosheath high speed jets(HSJs)under a quasi-parallel interplanetary magnetic field condition are studied using a threedimensional(3-D)global hybrid simulation.Soft X-ray intensity calculated based on both physical quantities of solar wind proton and oxygen ions is compared.We obtain key findings concerning deformations at the magnetopause:(1)Magnetopause deformations are highly coherent with the magnetosheath HSJs generated at the quasi-parallel region of the bow shock,(2)X-ray intensities estimated using solar wind h+and self-consistentO7+ions are consistent with each other,(3)Visual spacecraft are employed to check the discrimination ability for capturing magnetopause deformations on Lunar and polar orbits,respectively.The SMILE spacecraft on the polar orbit could be expected to provide opportunities for capturing the global geometry of the magnetopause in the equatorial plane.A striking point is that SMILE has the potential to capture small-scale magnetopause deformations and magnetosheath transients,such as HSJs,at medium altitudes on its orbit.Simulation results also demonstrate that a lunar based imager(e.g.,Lunar Environment heliospheric X-ray Imager,LEXI)is expected to observe a localized brightening of the magnetosheath during HSJ events in the meridian plane.These preliminary results might contribute to the pre-studies for the SMILE and LEXI missions by providing qualitative and quantitative soft X-ray estimates of dayside kinetic processes.展开更多
Two-dimensional particle-in-cell simulations are performed to study the coupling between ion and electron motions in collisionless magnetic reconnection.The electron diffusion region(EDR),where the electron motions ar...Two-dimensional particle-in-cell simulations are performed to study the coupling between ion and electron motions in collisionless magnetic reconnection.The electron diffusion region(EDR),where the electron motions are demagnetized,is found to have a two-layer structure:an inner EDR near the reconnection site and an outer EDR that is elongated to nearly 10 ion inertial lengths in the outflow direction.In the inner EDR,the speed of the electron outflow increases when the electrons move away from the X line.In the outer EDR,the speed of the electron outflow first increases and then decreases until the electrons reach the boundary of the outer EDR.In the boundary of the outer EDR,the magnetic field piles up and forms a depolarization front.From the perspective of the fluid,a force analysis on the formation of electron and ion outflows has also been investigated.Around the X line,the electrons are accelerated by the reconnection electric field in the out-of-plane direction.When the electrons move away from the X line,we find that the Lorentz force converts the direction of the accelerated electrons to the x direction,forming an electron outflow.Both electric field forces and electron gradient forces tend to drag the electron outflow.Ion acceleration along the x direction is caused by the Lorentz force,whereas the pressure gradient force tends to decelerate the ion outflow.Although these two terms are important,their effects on ions are almost offset.The Hall electric field force does positive work on ions and is not negligible.The ions are continuously accelerated,and the ion and electron outflow velocities are almost the same near the depolarization front.展开更多
Forecasting uncertainties among meteorological fields have long been recognized as the main limitation on the accuracy and predictability of air quality forecasts.However,the particular impact of meteorological foreca...Forecasting uncertainties among meteorological fields have long been recognized as the main limitation on the accuracy and predictability of air quality forecasts.However,the particular impact of meteorological forecasting uncertainties on air quality forecasts specific to different seasons is still not well known.In this study,a series of forecasts with different forecast lead times for January,April,July,and October of 2018 are conducted over the Beijing-Tianjin-Hebei(BTH)region and the impacts of meteorological forecasting uncertainties on surface PM_(2.5)concentration forecasts with each lead time are investigated.With increased lead time,the forecasted PM_(2.5)concentrations significantly change and demonstrate obvious seasonal variations.In general,the forecasting uncertainties in monthly mean surface PM_(2.5)concentrations in the BTH region due to lead time are the largest(80%)in spring,followed by autumn(~50%),summer(~40%),and winter(20%).In winter,the forecasting uncertainties in total surface PM_(2.5)mass due to lead time are mainly due to the uncertainties in PBL heights and hence the PBL mixing of anthropogenic primary particles.In spring,the forecasting uncertainties are mainly from the impacts of lead time on lower-tropospheric northwesterly winds,thereby further enhancing the condensation production of anthropogenic secondary particles by the long-range transport of natural dust.In summer,the forecasting uncertainties result mainly from the decrease in dry and wet deposition rates,which are associated with the reduction of near-surface wind speed and precipitation rate.In autumn,the forecasting uncertainties arise mainly from the change in the transport of remote natural dust and anthropogenic particles,which is associated with changes in the large-scale circulation.展开更多
In recent years,magnetic fields have been widely applied in catalysis to increase the performance of electrocatalysis,photocatalysis,and thermocatalysis through an important noncontact way.This work demonstrated that ...In recent years,magnetic fields have been widely applied in catalysis to increase the performance of electrocatalysis,photocatalysis,and thermocatalysis through an important noncontact way.This work demonstrated that doping CsPbCl_(3) halide perovskite nanocrystals with nickel ions(Ni^(2+))and applying an external magnetic field can significantly enhance the performance of the photocatalytic carbon dioxide reduction reaction(CO_(2)RR).Compared with its counterpart,Ni-doped CsPbCl_(3) exhibits a sixfold increase in CO_(2)RR efficiency under a 500 mT magnetic field.Insights into the mechanism of this enhancement effect were obtained through photogenerated current density measurements and X-ray magnetic circular dichroism.The results illustrate that the significant enhancement in catalytic performance by the magnetic field is attributed to the synergistic effects of magnetic element doping and the external magnetic field,leading to reduced electron‒hole recombination and extended carrier lifetimes.This study provides an effective strategy for enhancing the efficiency of the photocatalytic CO_(2)RR by manipulating spin-polarized electrons in photocatalytic semiconductors via a noncontact external magnetic field.展开更多
Distributed Acoustic Sensing(DAS) is an emerging technique for ultra-dense seismic observation, which provides a new method for high-resolution sub-surface seismic imaging. Recently a large number of linear DAS arrays...Distributed Acoustic Sensing(DAS) is an emerging technique for ultra-dense seismic observation, which provides a new method for high-resolution sub-surface seismic imaging. Recently a large number of linear DAS arrays have been used for two-dimensional S-wave near-surface imaging in urban areas. In order to explore the feasibility of three-dimensional(3D) structure imaging using a DAS array, we carried out an active source experiment at the Beijing National Earth Observatory. We deployed a 1 km optical cable in a rectangular shape, and the optical cable was recast into 250 sensors with a channel spacing of 4 m. The DAS array clearly recorded the P, S and surface waves generated by a hammer source. The first-arrival P wave travel times were first picked with a ShortTerm Average/Long-Term Average(STA/LTA) method and further manually checked. The P-wave signals recorded by the DAS are consistent with those recorded by the horizontal components of short-period seismometers. At shorter source-receiver distances, the picked P-wave arrivals from the DAS recording are consistent with vertical component recordings of seismometers, but they clearly lag behind the latter at greater distances.This is likely due to a combination of the signal-to-noise ratio and the polarization of the incoming wave. Then,we used the Tomo DD software to invert the 3D P-wave velocity structure for the uppermost 50 m with a resolution of 10 m. The inverted P-wave velocity structures agree well with the S-wave velocity structure previously obtained through ambient noise tomography. Our study indicates the feasibility of 3D near-surface imaging with the active source and DAS array. However, the inverted absolute velocity values at large depths may be biased due to potential time shifts between the DAS recording and seismometer at large source-receiver distances.展开更多
Aiming at improving the survey efficiency of the Wide Field Survey Telescope, we have developed a basic scheduling strategy that takes into account the telescope characteristics, observing conditions, and weather cond...Aiming at improving the survey efficiency of the Wide Field Survey Telescope, we have developed a basic scheduling strategy that takes into account the telescope characteristics, observing conditions, and weather conditions at the Lenghu site. The sky area is divided into rectangular regions, referred to as “tiles,” with a size of2°. 577 × 2°. 634 slightly smaller than the focal area of the mosaic CCDs. These tiles are continuously filled in annulars parallel to the equator. The brightness of the sky background, which varies with the moon phase and distance from the moon, plays a significant role in determining the accessible survey fields. Approximately 50connected tiles are grouped into one block for observation. To optimize the survey schedule, we perform simulations by taking into account the length of exposures, data readout, telescope slewing, and all relevant observing conditions. We utilize the Greedy Algorithm for scheduling optimization. Additionally, we propose a dedicated dithering pattern to cover the gaps between CCDs and the four corners of the mosaic CCD array, which are located outside of the 3° field of view. This dithering pattern helps to achieve relatively uniform exposure maps for the final survey outputs.展开更多
The evolution of ablative Rayleigh–Taylor instability(ARTI)induced by single-mode stationary and time-varying perturbations in heat flux is studied numerically in two dimensions.Compared with the stationary case,time...The evolution of ablative Rayleigh–Taylor instability(ARTI)induced by single-mode stationary and time-varying perturbations in heat flux is studied numerically in two dimensions.Compared with the stationary case,time-varying heat-flux perturbation mitigates ARTI growth because of the enhanced thermal smoothing induced by the wave-like traveling heat flux.A resonance is found to form when the phase velocity of the heat-flux perturbation matches the average sound speed in the ablation region.In the resonant regime,the coherent density and temperature fluctuations enhance the electron thermal conduction in the ablation region and lead to larger ablation pressure and effective acceleration,which consequently yield higher linear growth rate and saturated bubble velocity.The enhanced effective acceleration offers increased implosion velocity but can also compromise the integrity of inertial confinement fusion shells by causing faster ARTI growth.展开更多
Most existing star-galaxy classifiers depend on the reduced information from catalogs,necessitating careful data processing and feature extraction.In this study,we employ a supervised machine learning method(GoogLeNet...Most existing star-galaxy classifiers depend on the reduced information from catalogs,necessitating careful data processing and feature extraction.In this study,we employ a supervised machine learning method(GoogLeNet)to automatically classify stars and galaxies in the COSMOS field.Unlike traditional machine learning methods,we introduce several preprocessing techniques,including noise reduction and the unwrapping of denoised images in polar coordinates,applied to our carefully selected samples of stars and galaxies.By dividing the selected samples into training and validation sets in an 8:2 ratio,we evaluate the performance of the GoogLeNet model in distinguishing between stars and galaxies.The results indicate that the GoogLeNet model is highly effective,achieving accuracies of 99.6% and 99.9% for stars and galaxies,respectively.Furthermore,by comparing the results with and without preprocessing,we find that preprocessing can significantly improve classification accuracy(by approximately 2.0% to 6.0%)when the images are rotated.In preparation for the future launch of the China Space Station Telescope(CSST),we also evaluate the performance of the GoogLeNet model on the CSST simulation data.These results demonstrate a high level of accuracy(approximately 99.8%),indicating that this model can be effectively utilized for future observations with the CSST.展开更多
Brucite is a common hydrous mineral on Earth and may contribute to the deep water cycle of the Earth,but its stability and structure under mantle conditions remain uncertain.In this study,we investigated the stability...Brucite is a common hydrous mineral on Earth and may contribute to the deep water cycle of the Earth,but its stability and structure under mantle conditions remain uncertain.In this study,we investigated the stability of brucite up to 60 GPa at 800 K and 45 GPa at 1850 K.Within the experiment P-T conditions,no theoretically predicted new phase was observed,and brucite remained in the Pm1 structure.With the determined thermal EoS of brucite and the elastic parameters of mantle minerals,we modeled the velocity and density profile of subducted hydrous harzburgite in the top lower mantle,assuming that the water was stored in brucite and phase D.Based on the modelling,1 wt.%water will reduce the velocity and density of harzburgite by~5%and~2%,respectively,yet whether the water is stored in brucite or phase D has weak influence on both density and velocity.With a water content up to 2.4 wt.%,the density of hydrous harzburgite could be reduced to 2.2(2)%-2.8(2)%lower than the surrounding mantle,while the VP and VS of hydrous harzburgite are still 0.3(1)%-0.7(1)%and 0.7(2)%-1.8(2)%higher than that of the normal mantle.Thus,the low-density hydrous harzburgite may slow down the subducting of slab,despite being a high-velocity body in seismic observations.展开更多
Upgrades to power systems and the rapid growth of electric vehicles significantly heighten the importance of lithium-ion batteries(LiBs)in energy systems.As a complex dynamic system;the charging and discharging process...Upgrades to power systems and the rapid growth of electric vehicles significantly heighten the importance of lithium-ion batteries(LiBs)in energy systems.As a complex dynamic system;the charging and discharging process of LiBs involves the evolution of multiphysicsfields;such as concentration;electricity;and stress.For quantitative analysis of the internal mechanisms of LiBs;as well as the development guidance and performance prediction of high-performance batteries;modeling has advantages that cannot be matched by traditional experimental methods.Major research efforts in the past decades have made significant strides in modeling the internal processes and physicalfield evolution of LiBs.Importantly;the scattered ideas need to be integrated into a structured framework to form a complete LiBs multi-physicalfield model.This work reviews important ad-vances in LiBs modeling from the perspectives of describing the internal processes of the battery and portraying the evolution of the physicalfield.First;quantitative descriptions of the charging and discharging behaviors and the side reactions are reviewed to investigate the battery reaction mechanisms.In addition;the characterization of the evolution of the stress and temperaturefields within the battery as well as the coupling between them and the internal reactions are discussed.Finally;some suggestions for future improvements in the modeling are given;ranging from equation optimization to parameter acquisition and the application of artificial intelligence.It is hoped that this work will facilitate the development of models with sufficient accuracy and efficient computa-tional cost to provide guidance for the improvement of LiBs.展开更多
We investigate the sensitivity and performance of space-based optical lattice clocks(OLCs)in detecting gravitational waves,in particular the stochastic gravitational wave background(SGWB)at low frequencies(10^(-4),1)H...We investigate the sensitivity and performance of space-based optical lattice clocks(OLCs)in detecting gravitational waves,in particular the stochastic gravitational wave background(SGWB)at low frequencies(10^(-4),1)Hz,which are inaccessible to ground-based detectors.We first analyze the response characteristics of a single OLC detector for SGWB detection and compare its sensitivity with that of laser interferometer space antenna(LISA).Due to longer arm lengths,space-based OLC detectors can exhibit unique frequency responses and enhance the capability to detect SGWB in the low-frequency range,but the sensitivity of a single OLC detector remains insufficient overall compared with LISA.Then,as a preliminary plan,we adopt a method of crosscorrelation on two OLC detectors to improve the signal-to-noise ratio(SNR).This method leverages the uncorrelated origins but statistically similar properties of noise in two detectors while the SGWB signal is correlated between them,thus achieving effective noise suppression and sensitivity enhancement.Future advancements in OLC stability are expected to further enhance their detection performance.This work highlights the potential of OLC detectors as a promising platform for SGWB detection,offering complementary capabilities to LISA,and opening an observational window into more astrophysical sources and the early universe.展开更多
The core-mantle differentiation process plays a pivotal role in redistributing material on a massive scale,shaping the long-term evolution of rocky planets.Understanding this process is crucial for gaining insights in...The core-mantle differentiation process plays a pivotal role in redistributing material on a massive scale,shaping the long-term evolution of rocky planets.Understanding this process is crucial for gaining insights into the accretion and evolution of planets like Mars.However,the details of Mars’s core-mantle differentiation remain poorly understood due to limited compositional data for its core and mantle.In this study,we aim to constrain the Martian core-mantle differentiation by examining FeO partitioning between core and mantle materials,incorporating improved Martian compositional data from the InSight mission.Using ab initio thermodynamic techniques,we calculated the FeO partition coefficient between liquid iron and silicate melt.Our results align with previous studies while also clarifying the factors affecting partitioning behavior.Based on these findings and estimates of oxygen concentration in the core,we infer that Mars’s core and mantle likely differentiated at temperatures above 2440 K and pressures ranging from 14 to 22 GPa.Although these estimates are higher than previously reported,they are consistent with observed abundances of moderately siderophile elements and Mars’s accretion models.展开更多
Expected to be of the highest survey power telescope in the northern hemisphere,the Wide Field Survey Telescope(WFST)will begin its routine observations of the northern sky since 2023.WFST will produce a lot of scient...Expected to be of the highest survey power telescope in the northern hemisphere,the Wide Field Survey Telescope(WFST)will begin its routine observations of the northern sky since 2023.WFST will produce a lot of scientific data to support the researches of time-domain astronomy,asteroids and the solar system,galaxy formation and cosmology and so on.We estimated that the 5σlimiting magnitudes of WFST with 30 s exposure are u=22.31mag,g=23.42 mag,r=22.95 mag,i=22.43 mag,z=21.50 mag,w=23.61 mag.The above values are calculated for the conditions of airmass=1.2,seeing=075,precipitable water vapor=2.5 mm and Moon-object separation=45°at the darkest New Moon night of the Lenghu site(V=22.30 mag,Moon phaseθ=0°).The limiting magnitudes in different Moon phase conditions are also calculated.The calculations are based on the empirical transmittance data of WFST optics,the vendor provided CCD quantum efficiency,the atmospherical model transmittance and spectrum of the site.In the absence of measurement data such as sky transmittance and spectrum,we use model data.展开更多
The Mars Orbiter MAGnetometer(MOMAG)is a scientific instrument onboard the orbiter of China’s first mission for Mars—Tianwen-1.Since November 13,2021,it has been recording magnetic field data from the solar wind to ...The Mars Orbiter MAGnetometer(MOMAG)is a scientific instrument onboard the orbiter of China’s first mission for Mars—Tianwen-1.Since November 13,2021,it has been recording magnetic field data from the solar wind to the magnetic pile-up region surrounding Mars.Here we present its in-flight performance and first science results,based on its first one and one-half months’data.Comparing these early MOMAG observations to the magnetic field data in the solar wind from NASA’s Mars Atmosphere and Volatile EvolutioN(MAVEN)mission,we report that the MOMAG magnetic field data are at the same level in magnitude,and describe the same magnetic structures with similar variations in three components.We recognize 158 clear bow shock(BS)crossings in these MOMAG data;their locations match well statistically with the modeled average BS.We also identify and compare five pairs of datasets collected when Tianwen-1’s orbiter and the MAVEN probe made simultaneous BS crossings.These BS crossings confirm the global shape of modeled BS,as well as the south-north asymmetry of the Martian BS.Two cases presented in this paper suggest that the BS is probably more dynamic at flank than near the nose.So far,MOMAG performs well,and provides accurate magnetic field vectors.MOMAG is continuously scanning the magnetic field surrounding Mars.Data from MOMAG’s measurements complement data from MAVEN and will undoubt edly advance our understanding of the plasma environment of Mars.展开更多
Mineralogical evidence of water–rock interactions is a strong indicator of the presence of liquid water on ancient Mars.Previous observations have found widely distributed hydrated minerals in the southern highlands,...Mineralogical evidence of water–rock interactions is a strong indicator of the presence of liquid water on ancient Mars.Previous observations have found widely distributed hydrated minerals in the southern highlands,whereas such discoveries have been rare in the younger northern lowlands.China’s first Mars exploration mission successfully landed a rover(Zhurong)in southern Utopia Planitia,providing an opportunity to analyze the exposed rocks in the northern lowlands.Using data from the short-wave infrared(SWIR)spectrometer and the laser-induced breakdown spectrometer(LIBS)onboard the Zhurong rover,we found evidence for the widespread presence of hydrated minerals(probably sulfates or silica)around the landing site.The basaltic-like elemental compositions of the targeted samples further indicated that hydrated minerals are likely minor components.The results from Zhurong suggest that active aqueous activities occurred during the overall cold and dry Amazonian era on Mars.However,further evaluations are needed on the duration and scale of these activities.展开更多
基金supported by the Project of Stable Support for Youth Team in Basic Research Field,CAS(grant No.YSBR-018)the National Natural Science Foundation of China(grant Nos.42188101,42130204)+4 种基金the B-type Strategic Priority Program of CAS(grant no.XDB41000000)the National Natural Science Foundation of China(NSFC)Distinguished Overseas Young Talents Program,Innovation Program for Quantum Science and Technology(2021ZD0300301)the Open Research Project of Large Research Infrastructures of CAS-“Study on the interaction between low/mid-latitude atmosphere and ionosphere based on the Chinese Meridian Project”.The project was supported also by the National Key Laboratory of Deep Space Exploration(Grant No.NKLDSE2023A002)the Open Fund of Anhui Provincial Key Laboratory of Intelligent Underground Detection(Grant No.APKLIUD23KF01)the China National Space Administration(CNSA)pre-research Project on Civil Aerospace Technologies No.D010305,D010301.
文摘Sporadic E(Es)layers in the ionosphere are characterized by intense plasma irregularities in the E region at altitudes of 90-130 km.Because they can significantly influence radio communications and navigation systems,accurate forecasting of Es layers is crucial for ensuring the precision and dependability of navigation satellite systems.In this study,we present Es predictions made by an empirical model and by a deep learning model,and analyze their differences comprehensively by comparing the model predictions to satellite RO measurements and ground-based ionosonde observations.The deep learning model exhibited significantly better performance,as indicated by its high coefficient of correlation(r=0.87)with RO observations and predictions,than did the empirical model(r=0.53).This study highlights the importance of integrating artificial intelligence technology into ionosphere modelling generally,and into predicting Es layer occurrences and characteristics,in particular.
基金the National Natural Science Founda-tion of China(NSFC,Grant No.42174181)and the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDJ-SSW-DQC010).
文摘The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sheet.The ions were demagnetized inside the electron current layer,but the electrons were still frozen in with the magnetic field line.Thus,this decoupling of ions and electrons gave rise to a strong Hall electric field,which could be the reason for the formation of the embedded thin current layer.The magnetized electrons,the absence of the nongyrotropic electron distribution,and negligible energy dissipation in the layer indicate that magnetic reconnection had not been triggered within the embedded thin current layer.The highly asymmetric plasma on the two sides of the current layer and low magnetic shear across it could suppress magnetic reconnection.The observations indicate that the embedded electric current layer,probably generated by the Hall electric field,even down to electron scale,is not a sufficient condition for magnetic reconnection.
基金supported by National Natural Science Foundation of China(Grant No.42473017)Hong Kong RGC grants(JLFS/P-702/24 and 17308023)China Geological Survey project(Grant No.DD20242037).
文摘To investigate the stable chromium(Cr)isotope variations during melt percolation in the mantle,we ana-lyzed the Cr isotopic compositions of fresh ultramafic rocks from the Balmuccia and Baldissero peridotite massifs located in the Italian Alps.These massifs represent fragments of the subcontinental lithospheric mantle.The samples collected included lherzolites,harzburgites,dunites,and pyroxenites.Lherzolites,formed through 5%-15%fractional melting of a primitive mantle source,exhibited δ^(53)Crvalues ranging from−0.13‰±0.03‰to−0.03‰±0.03‰.These values correlated negatively with Al_(2)O_(3)content,sug-gesting that partial melting induces Cr isotopic fractionation between the melts and residual peridotites.Harzburgites and dunites,influenced by the silicate melt percolation,displayed distinctδ^(53)Cr values.Notably,dunites not spatially associated with the pyroxenite veins exhibited slightly elevatedδ^(53)Cr val-ues(−0.05‰±0.03‰to 0.10‰±0.03‰)relative to lherzolites.This difference likely resulted from pyroxene dissolution and olivine precipitation during melt percolation processes.However,one dunite sample in direct contact with pyroxenite veins showed lowerδ^(53)Cr values(−0.26‰±0.03‰),possibly owing to the kinetic effects during silicate melt percolation.Pyroxenites are formed through the interac-tion of basaltic melts with the surrounding peridotite via a metasomatic reaction or crystallization in a vein.Most of theirδ^(53)Cr values(−0.26‰±0.03‰to−0.13‰±0.03‰)are positively correlated with MgO contents,suggesting that they were influenced by magmatic differentiation.However,two subsam-ples from a single clinopyroxenite vein exhibit anomalously lowδ^(53)Crvalues(−0.30‰±0.03‰and−0.43‰±0.03‰),which are attributed to kinetic isotopic fractionation during melt-percolation pro-cesses.Our findings suggest that melt percolation processes in the mantle contribute to the Cr isotopic heterogeneity observed within the Earth’s mantle.
基金supported by the National Natural Science Foundation of China(Grant No.12473063,12461160265,and 62227901)Shenzhen Science and Technology Innovation Commission(Grant No.20231121103211001)+5 种基金the Opening Fund of the Key Laboratory of Lunar and Deep Space Exploration,Chinese Academy of Sciences(No.LDSE202005)the Shenzhen University 2035 Program for Excellent Research(Grant No.2024C009)China National University Student Innovation&Entrepreneurship Development Program(No.202410590011)Natural Science Foundation of Guangdong Province(No.2024A1515011275)the Shenzhen Municipal Government Investment Project(No.2106_440300_04_03_901272)the team“Searching For Subglacial Water On Mars With Orbiting Ground Penetrating Radars”of the International Space Science Institute(ISSI).
文摘Asteroids and comets,which have long been of interest to astronomers,are important components of the solar system.They contain rich primitive information about the early solar system,which provide a unique pathway for studying the formation and evolution of the solar system,and even the origin of life on planet Earth.In this review,the formation,evolution processes and the internal characteristics of the asteroids and comets in the solar system are presented.The focus of this review is on the internal characteristics especially the dielectric properties of asteroids and comets by radar observations.On this basis,the possible internal structure of these celestial bodies is discussed.Combined with the existing theories,simulations and experiments,the possible internal structure of near-Earth asteroid 2016 HO_(3) is a monolith while structure of active asteroid 311P/PANSTARRS remains unknown.In 2025,China will launch Tianwen-2 asteroid-comet exploration mission to detect 2016 HO_(3) and 311P/PANSTARRS,which will carry a penetrating radar to observe the internal characteristics of these two objects.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42188101, 42274211, 41974170, 42374184, 42122032, and 41974196)the Chinese Academy of Sciences (Grant Nos. QYZDJSSW-JSC028, XDA15052500, XDA17010301, and XDB41000000)+3 种基金the CNSA (Grant No. D050103)the Specialized Research Fund for State Key Laboratories of Chinathe Specialized Research Fund for Laboratory of Geospace Environment of the University of Science and Technology of Chinasupported by the International Space Science Institute (ISSI) in Bern and Beijing through the ISSI/ISSI-BJ International Team Project titled “Understanding the Mars Space Environment Through Multi-Spacecraft Measurements” (ISSI Team Project No. 23-582 and ISSI-BJ Team Project No. 58)
文摘Atmospheric escape plays a critical role in shaping the long-term climate evolution of Mars.Among the various escape mechanisms,energetic neutral atoms(ENAs)generated through charge exchange between solar wind ions and exospheric neutrals serve as an important diagnostic for ion-neutral interactions and upper atmospheric loss.This study presents direct observations of hydrogen ENAs(H-ENAs)on the dayside of Mars by using the Mars Ion and Neutral Particle Analyzer(MINPA)onboard China’s Tianwen-1 orbiter.By analyzing H-ENA data during a coronal mass ejection and a stream interaction region from December 29,2021,to January 1,2022,and comparing these data with MAVEN/SWIA(Mars Atmosphere and Volatile EvolutioN/Solar Wind Ion Analyzer)solar wind measurements,we examine the temporal evolution of H-ENA flux and the associated sputtered escape of atmospheric constituents.The observed H-ENA velocity is consistent with upstream solar wind ions,and the H-ENA-to-ion intensity ratio is used to infer variations in exospheric density,revealing a delayed response to enhanced solar wind activity.Penetrating H-ENA intensities reach up to 5.3×10^(6)s^(−1) cm^(−2),with energy fluxes on the order of(0.5-8.1)×10^(−3) mW/m^(2).The estimated oxygen sputtered escape rate driven by penetrating H-ENAs ranges from 5.5×10^(23)s^(−1) to 5.2×10^(24)s^(−1),comparable to or exceeding previous estimates based on penetrating ions.The findings highlight the need for low-altitude H-ENA observations to better quantify their atmospheric interactions and refine our understanding of nonthermal escape processes at Mars.
基金supported by the National Key R&D program of China No.2021YFA0718600NNFSC grants 42150105,42188101,and 42274210the Specialized Research Fund for State Key Laboratories of China。
文摘The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)is a joint mission of the European Space Agency(ESA)and the Chinese Academy of Sciences(CAS).Primary goals are investigating the dynamic response of the Earth's magnetosphere to the solar wind(SW)impact via simultaneous in situ magnetosheath plasma and magnetic field measurements,X-Ray images of the magnetosheath and magnetic cusps,and UV images of global auroral distributions.Magnetopause deformations associated with magnetosheath high speed jets(HSJs)under a quasi-parallel interplanetary magnetic field condition are studied using a threedimensional(3-D)global hybrid simulation.Soft X-ray intensity calculated based on both physical quantities of solar wind proton and oxygen ions is compared.We obtain key findings concerning deformations at the magnetopause:(1)Magnetopause deformations are highly coherent with the magnetosheath HSJs generated at the quasi-parallel region of the bow shock,(2)X-ray intensities estimated using solar wind h+and self-consistentO7+ions are consistent with each other,(3)Visual spacecraft are employed to check the discrimination ability for capturing magnetopause deformations on Lunar and polar orbits,respectively.The SMILE spacecraft on the polar orbit could be expected to provide opportunities for capturing the global geometry of the magnetopause in the equatorial plane.A striking point is that SMILE has the potential to capture small-scale magnetopause deformations and magnetosheath transients,such as HSJs,at medium altitudes on its orbit.Simulation results also demonstrate that a lunar based imager(e.g.,Lunar Environment heliospheric X-ray Imager,LEXI)is expected to observe a localized brightening of the magnetosheath during HSJ events in the meridian plane.These preliminary results might contribute to the pre-studies for the SMILE and LEXI missions by providing qualitative and quantitative soft X-ray estimates of dayside kinetic processes.
基金the National Key Research and Development Program of China(Grant No.2022YFA1604600)the National Natural Science Foundation of China(NSFC,Grant No.42174181)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB 41000000).
文摘Two-dimensional particle-in-cell simulations are performed to study the coupling between ion and electron motions in collisionless magnetic reconnection.The electron diffusion region(EDR),where the electron motions are demagnetized,is found to have a two-layer structure:an inner EDR near the reconnection site and an outer EDR that is elongated to nearly 10 ion inertial lengths in the outflow direction.In the inner EDR,the speed of the electron outflow increases when the electrons move away from the X line.In the outer EDR,the speed of the electron outflow first increases and then decreases until the electrons reach the boundary of the outer EDR.In the boundary of the outer EDR,the magnetic field piles up and forms a depolarization front.From the perspective of the fluid,a force analysis on the formation of electron and ion outflows has also been investigated.Around the X line,the electrons are accelerated by the reconnection electric field in the out-of-plane direction.When the electrons move away from the X line,we find that the Lorentz force converts the direction of the accelerated electrons to the x direction,forming an electron outflow.Both electric field forces and electron gradient forces tend to drag the electron outflow.Ion acceleration along the x direction is caused by the Lorentz force,whereas the pressure gradient force tends to decelerate the ion outflow.Although these two terms are important,their effects on ions are almost offset.The Hall electric field force does positive work on ions and is not negligible.The ions are continuously accelerated,and the ion and electron outflow velocities are almost the same near the depolarization front.
基金supported by the National Key Research and Development Program of China(No.2022YFC3700701)National Natural Science Foundation of China(Grant Nos.41775146,42061134009)+1 种基金USTC Research Funds of the Double First-Class Initiative(YD2080002007)Strategic Priority Research Program of Chinese Academy of Sciences(XDB41000000).
文摘Forecasting uncertainties among meteorological fields have long been recognized as the main limitation on the accuracy and predictability of air quality forecasts.However,the particular impact of meteorological forecasting uncertainties on air quality forecasts specific to different seasons is still not well known.In this study,a series of forecasts with different forecast lead times for January,April,July,and October of 2018 are conducted over the Beijing-Tianjin-Hebei(BTH)region and the impacts of meteorological forecasting uncertainties on surface PM_(2.5)concentration forecasts with each lead time are investigated.With increased lead time,the forecasted PM_(2.5)concentrations significantly change and demonstrate obvious seasonal variations.In general,the forecasting uncertainties in monthly mean surface PM_(2.5)concentrations in the BTH region due to lead time are the largest(80%)in spring,followed by autumn(~50%),summer(~40%),and winter(20%).In winter,the forecasting uncertainties in total surface PM_(2.5)mass due to lead time are mainly due to the uncertainties in PBL heights and hence the PBL mixing of anthropogenic primary particles.In spring,the forecasting uncertainties are mainly from the impacts of lead time on lower-tropospheric northwesterly winds,thereby further enhancing the condensation production of anthropogenic secondary particles by the long-range transport of natural dust.In summer,the forecasting uncertainties result mainly from the decrease in dry and wet deposition rates,which are associated with the reduction of near-surface wind speed and precipitation rate.In autumn,the forecasting uncertainties arise mainly from the change in the transport of remote natural dust and anthropogenic particles,which is associated with changes in the large-scale circulation.
基金supported by the National Key R&D Program of China(2021YFA1501003)the Joint Funds of the National Natural Science Foundation of China(U23A2081)+5 种基金the National Natural Science Foundation of China(92261105,22221003)the Anhui Provincial Key Research and Development Project(2023z04020010,2022a05020053)the Anhui Provincial Natural Science Foundation(2108085UD06,2208085UD04)the USTC Research Funds of the Double First Class Initiative(YD2060002029,YD2060006005)the Fundamental Research Funds for the Central Universities(WK2060000004,WK2060000021,WK2060000025,WK9990000155)the Joint Funds from Hefei National Synchrotron Radiation Laboratory(KY2060000180,KY2060000195).
文摘In recent years,magnetic fields have been widely applied in catalysis to increase the performance of electrocatalysis,photocatalysis,and thermocatalysis through an important noncontact way.This work demonstrated that doping CsPbCl_(3) halide perovskite nanocrystals with nickel ions(Ni^(2+))and applying an external magnetic field can significantly enhance the performance of the photocatalytic carbon dioxide reduction reaction(CO_(2)RR).Compared with its counterpart,Ni-doped CsPbCl_(3) exhibits a sixfold increase in CO_(2)RR efficiency under a 500 mT magnetic field.Insights into the mechanism of this enhancement effect were obtained through photogenerated current density measurements and X-ray magnetic circular dichroism.The results illustrate that the significant enhancement in catalytic performance by the magnetic field is attributed to the synergistic effects of magnetic element doping and the external magnetic field,leading to reduced electron‒hole recombination and extended carrier lifetimes.This study provides an effective strategy for enhancing the efficiency of the photocatalytic CO_(2)RR by manipulating spin-polarized electrons in photocatalytic semiconductors via a noncontact external magnetic field.
基金supported by the National Key R&D Program of China(2022YFC3102202)the Chinese Academy of Sciences (CAS) Project for Young Scientists in Basic Research (YSBR-020)。
文摘Distributed Acoustic Sensing(DAS) is an emerging technique for ultra-dense seismic observation, which provides a new method for high-resolution sub-surface seismic imaging. Recently a large number of linear DAS arrays have been used for two-dimensional S-wave near-surface imaging in urban areas. In order to explore the feasibility of three-dimensional(3D) structure imaging using a DAS array, we carried out an active source experiment at the Beijing National Earth Observatory. We deployed a 1 km optical cable in a rectangular shape, and the optical cable was recast into 250 sensors with a channel spacing of 4 m. The DAS array clearly recorded the P, S and surface waves generated by a hammer source. The first-arrival P wave travel times were first picked with a ShortTerm Average/Long-Term Average(STA/LTA) method and further manually checked. The P-wave signals recorded by the DAS are consistent with those recorded by the horizontal components of short-period seismometers. At shorter source-receiver distances, the picked P-wave arrivals from the DAS recording are consistent with vertical component recordings of seismometers, but they clearly lag behind the latter at greater distances.This is likely due to a combination of the signal-to-noise ratio and the polarization of the incoming wave. Then,we used the Tomo DD software to invert the 3D P-wave velocity structure for the uppermost 50 m with a resolution of 10 m. The inverted P-wave velocity structures agree well with the S-wave velocity structure previously obtained through ambient noise tomography. Our study indicates the feasibility of 3D near-surface imaging with the active source and DAS array. However, the inverted absolute velocity values at large depths may be biased due to potential time shifts between the DAS recording and seismometer at large source-receiver distances.
基金supported by the National Natural Science Foundation of China (12233005, 12073078 and 12173088)the science research grants from the China Manned Space Project with NO. CMS-CSST-2021-A02, CMS-CSST-2021-A04 and CMS-CSST-2021-A07grants from the Cyrus Chun Ying Tang Foundations。
文摘Aiming at improving the survey efficiency of the Wide Field Survey Telescope, we have developed a basic scheduling strategy that takes into account the telescope characteristics, observing conditions, and weather conditions at the Lenghu site. The sky area is divided into rectangular regions, referred to as “tiles,” with a size of2°. 577 × 2°. 634 slightly smaller than the focal area of the mosaic CCDs. These tiles are continuously filled in annulars parallel to the equator. The brightness of the sky background, which varies with the moon phase and distance from the moon, plays a significant role in determining the accessible survey fields. Approximately 50connected tiles are grouped into one block for observation. To optimize the survey schedule, we perform simulations by taking into account the length of exposures, data readout, telescope slewing, and all relevant observing conditions. We utilize the Greedy Algorithm for scheduling optimization. Additionally, we propose a dedicated dithering pattern to cover the gaps between CCDs and the four corners of the mosaic CCD array, which are located outside of the 3° field of view. This dithering pattern helps to achieve relatively uniform exposure maps for the final survey outputs.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA25050400 and XDA25010200)the National Natural Science Foundation of China(Grant No.12175229 and 12388101)+1 种基金the Frontier Scientific Research Program of the Deep Space Exploration Laboratory(Grant No.2022-QYKYJH-HXYF-019)by the Fundamental Research Funds for the Central Universities.
文摘The evolution of ablative Rayleigh–Taylor instability(ARTI)induced by single-mode stationary and time-varying perturbations in heat flux is studied numerically in two dimensions.Compared with the stationary case,time-varying heat-flux perturbation mitigates ARTI growth because of the enhanced thermal smoothing induced by the wave-like traveling heat flux.A resonance is found to form when the phase velocity of the heat-flux perturbation matches the average sound speed in the ablation region.In the resonant regime,the coherent density and temperature fluctuations enhance the electron thermal conduction in the ablation region and lead to larger ablation pressure and effective acceleration,which consequently yield higher linear growth rate and saturated bubble velocity.The enhanced effective acceleration offers increased implosion velocity but can also compromise the integrity of inertial confinement fusion shells by causing faster ARTI growth.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(grant No.XDB41000000)the National Natural Science Foundation of China(NSFC,Grant Nos.12233008 and 11973038)+2 种基金the China Manned Space Project(No.CMS-CSST-2021-A07)the Cyrus Chun Ying Tang Foundationsthe support from Hong Kong Innovation and Technology Fund through the Research Talent Hub program(GSP028)。
文摘Most existing star-galaxy classifiers depend on the reduced information from catalogs,necessitating careful data processing and feature extraction.In this study,we employ a supervised machine learning method(GoogLeNet)to automatically classify stars and galaxies in the COSMOS field.Unlike traditional machine learning methods,we introduce several preprocessing techniques,including noise reduction and the unwrapping of denoised images in polar coordinates,applied to our carefully selected samples of stars and galaxies.By dividing the selected samples into training and validation sets in an 8:2 ratio,we evaluate the performance of the GoogLeNet model in distinguishing between stars and galaxies.The results indicate that the GoogLeNet model is highly effective,achieving accuracies of 99.6% and 99.9% for stars and galaxies,respectively.Furthermore,by comparing the results with and without preprocessing,we find that preprocessing can significantly improve classification accuracy(by approximately 2.0% to 6.0%)when the images are rotated.In preparation for the future launch of the China Space Station Telescope(CSST),we also evaluate the performance of the GoogLeNet model on the CSST simulation data.These results demonstrate a high level of accuracy(approximately 99.8%),indicating that this model can be effectively utilized for future observations with the CSST.
基金supported by National Key R&D Program of China(2018YFA0702703)National Natural Science Foundation of China(42002036)+5 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB18000000)the Fundamental Research Funds for the Central Universities(WK2080000144,WK2080000189)supported by the National Science Foundation-Earth Sciences(EAR-1128799)Department of Energy-GeoSciences(DE-FG02-94ER14466)supported by DOE-BES,under Contract No.DE-AC02-06CH11357BL15U1 of Shanghai Synchrotron Radiation Facility(proposal 2019-SSRF-PT-011379).
文摘Brucite is a common hydrous mineral on Earth and may contribute to the deep water cycle of the Earth,but its stability and structure under mantle conditions remain uncertain.In this study,we investigated the stability of brucite up to 60 GPa at 800 K and 45 GPa at 1850 K.Within the experiment P-T conditions,no theoretically predicted new phase was observed,and brucite remained in the Pm1 structure.With the determined thermal EoS of brucite and the elastic parameters of mantle minerals,we modeled the velocity and density profile of subducted hydrous harzburgite in the top lower mantle,assuming that the water was stored in brucite and phase D.Based on the modelling,1 wt.%water will reduce the velocity and density of harzburgite by~5%and~2%,respectively,yet whether the water is stored in brucite or phase D has weak influence on both density and velocity.With a water content up to 2.4 wt.%,the density of hydrous harzburgite could be reduced to 2.2(2)%-2.8(2)%lower than the surrounding mantle,while the VP and VS of hydrous harzburgite are still 0.3(1)%-0.7(1)%and 0.7(2)%-1.8(2)%higher than that of the normal mantle.Thus,the low-density hydrous harzburgite may slow down the subducting of slab,despite being a high-velocity body in seismic observations.
基金funding support from National Key R&D Program of China(2023YFB2408100)Chinese Academy of Sciences Project for Young Scientists in Basic Research(YSBR-098)National Innovative Talents Program(GG2090007001).
文摘Upgrades to power systems and the rapid growth of electric vehicles significantly heighten the importance of lithium-ion batteries(LiBs)in energy systems.As a complex dynamic system;the charging and discharging process of LiBs involves the evolution of multiphysicsfields;such as concentration;electricity;and stress.For quantitative analysis of the internal mechanisms of LiBs;as well as the development guidance and performance prediction of high-performance batteries;modeling has advantages that cannot be matched by traditional experimental methods.Major research efforts in the past decades have made significant strides in modeling the internal processes and physicalfield evolution of LiBs.Importantly;the scattered ideas need to be integrated into a structured framework to form a complete LiBs multi-physicalfield model.This work reviews important ad-vances in LiBs modeling from the perspectives of describing the internal processes of the battery and portraying the evolution of the physicalfield.First;quantitative descriptions of the charging and discharging behaviors and the side reactions are reviewed to investigate the battery reaction mechanisms.In addition;the characterization of the evolution of the stress and temperaturefields within the battery as well as the coupling between them and the internal reactions are discussed.Finally;some suggestions for future improvements in the modeling are given;ranging from equation optimization to parameter acquisition and the application of artificial intelligence.It is hoped that this work will facilitate the development of models with sufficient accuracy and efficient computa-tional cost to provide guidance for the improvement of LiBs.
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFC2207500 and 2021YFC2203100)the CAS Young Interdisciplinary Innovation Team(Grant No.JCTD-2022-20)+5 种基金the Fundamental Research Funds for Central Universitiesthe National Natural Science Foundation of China(Grant Nos.92476203,12433002 and12261131497)the 111 Project(Grant No.B23042)the CSC Innovation Talent Fundsthe USTC Fellowships for International Cooperationthe USTC Research Funds of the Double First-Class Initiative。
文摘We investigate the sensitivity and performance of space-based optical lattice clocks(OLCs)in detecting gravitational waves,in particular the stochastic gravitational wave background(SGWB)at low frequencies(10^(-4),1)Hz,which are inaccessible to ground-based detectors.We first analyze the response characteristics of a single OLC detector for SGWB detection and compare its sensitivity with that of laser interferometer space antenna(LISA).Due to longer arm lengths,space-based OLC detectors can exhibit unique frequency responses and enhance the capability to detect SGWB in the low-frequency range,but the sensitivity of a single OLC detector remains insufficient overall compared with LISA.Then,as a preliminary plan,we adopt a method of crosscorrelation on two OLC detectors to improve the signal-to-noise ratio(SNR).This method leverages the uncorrelated origins but statistically similar properties of noise in two detectors while the SGWB signal is correlated between them,thus achieving effective noise suppression and sensitivity enhancement.Future advancements in OLC stability are expected to further enhance their detection performance.This work highlights the potential of OLC detectors as a promising platform for SGWB detection,offering complementary capabilities to LISA,and opening an observational window into more astrophysical sources and the early universe.
基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB41000000)the Program for Innovative Research Team of USTC(WK3410000019)+2 种基金support of the National Natural Science Foundation of China(42322201,42173040)the support from CAs Hundred Talents Program.You Zhou acknowledges the support of the National Natural Science Foundation of China(41973063,42241142)computing system in the Supercomputing Center of University of Science and Technology of China.
文摘The core-mantle differentiation process plays a pivotal role in redistributing material on a massive scale,shaping the long-term evolution of rocky planets.Understanding this process is crucial for gaining insights into the accretion and evolution of planets like Mars.However,the details of Mars’s core-mantle differentiation remain poorly understood due to limited compositional data for its core and mantle.In this study,we aim to constrain the Martian core-mantle differentiation by examining FeO partitioning between core and mantle materials,incorporating improved Martian compositional data from the InSight mission.Using ab initio thermodynamic techniques,we calculated the FeO partition coefficient between liquid iron and silicate melt.Our results align with previous studies while also clarifying the factors affecting partitioning behavior.Based on these findings and estimates of oxygen concentration in the core,we infer that Mars’s core and mantle likely differentiated at temperatures above 2440 K and pressures ranging from 14 to 22 GPa.Although these estimates are higher than previously reported,they are consistent with observed abundances of moderately siderophile elements and Mars’s accretion models.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(grant Nos.XDB 41000000 and XDB 41010105)the National Science Foundation of China(NSFC,grant Nos.12233008,12173037 and 11973038)+1 种基金the China Manned Space Project(No.CMS-CSST-2021-A07)the Cyrus Chun Ying Tang Foundations。
文摘Expected to be of the highest survey power telescope in the northern hemisphere,the Wide Field Survey Telescope(WFST)will begin its routine observations of the northern sky since 2023.WFST will produce a lot of scientific data to support the researches of time-domain astronomy,asteroids and the solar system,galaxy formation and cosmology and so on.We estimated that the 5σlimiting magnitudes of WFST with 30 s exposure are u=22.31mag,g=23.42 mag,r=22.95 mag,i=22.43 mag,z=21.50 mag,w=23.61 mag.The above values are calculated for the conditions of airmass=1.2,seeing=075,precipitable water vapor=2.5 mm and Moon-object separation=45°at the darkest New Moon night of the Lenghu site(V=22.30 mag,Moon phaseθ=0°).The limiting magnitudes in different Moon phase conditions are also calculated.The calculations are based on the empirical transmittance data of WFST optics,the vendor provided CCD quantum efficiency,the atmospherical model transmittance and spectrum of the site.In the absence of measurement data such as sky transmittance and spectrum,we use model data.
基金supported by the NSFC(Grant Nos 42130204 and 42188101)the Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB41000000)the support of the Tencent Foundation.
文摘The Mars Orbiter MAGnetometer(MOMAG)is a scientific instrument onboard the orbiter of China’s first mission for Mars—Tianwen-1.Since November 13,2021,it has been recording magnetic field data from the solar wind to the magnetic pile-up region surrounding Mars.Here we present its in-flight performance and first science results,based on its first one and one-half months’data.Comparing these early MOMAG observations to the magnetic field data in the solar wind from NASA’s Mars Atmosphere and Volatile EvolutioN(MAVEN)mission,we report that the MOMAG magnetic field data are at the same level in magnitude,and describe the same magnetic structures with similar variations in three components.We recognize 158 clear bow shock(BS)crossings in these MOMAG data;their locations match well statistically with the modeled average BS.We also identify and compare five pairs of datasets collected when Tianwen-1’s orbiter and the MAVEN probe made simultaneous BS crossings.These BS crossings confirm the global shape of modeled BS,as well as the south-north asymmetry of the Martian BS.Two cases presented in this paper suggest that the BS is probably more dynamic at flank than near the nose.So far,MOMAG performs well,and provides accurate magnetic field vectors.MOMAG is continuously scanning the magnetic field surrounding Mars.Data from MOMAG’s measurements complement data from MAVEN and will undoubt edly advance our understanding of the plasma environment of Mars.
基金funded by the Strategic Priority Research Program (B) of Chinese Academy of Sciences (Grant No. XDB41000000)the National Natural Science Foundation of China (Grant No. 41930216)+1 种基金the Pre-research Project on Civil Aerospace Technologies (Grant No. D020202) of the Chinese National Space Administrationthe Fundamental Research Funds for the Central Universities of China (Grant No. WK3410000019)。
文摘Mineralogical evidence of water–rock interactions is a strong indicator of the presence of liquid water on ancient Mars.Previous observations have found widely distributed hydrated minerals in the southern highlands,whereas such discoveries have been rare in the younger northern lowlands.China’s first Mars exploration mission successfully landed a rover(Zhurong)in southern Utopia Planitia,providing an opportunity to analyze the exposed rocks in the northern lowlands.Using data from the short-wave infrared(SWIR)spectrometer and the laser-induced breakdown spectrometer(LIBS)onboard the Zhurong rover,we found evidence for the widespread presence of hydrated minerals(probably sulfates or silica)around the landing site.The basaltic-like elemental compositions of the targeted samples further indicated that hydrated minerals are likely minor components.The results from Zhurong suggest that active aqueous activities occurred during the overall cold and dry Amazonian era on Mars.However,further evaluations are needed on the duration and scale of these activities.
