The present paper describes a numerical two-way coupling model for shock-induced laminar boundary-layer flows of a dust-laden gas and studies the transverse migration of fine particles under the action of Saffman lift...The present paper describes a numerical two-way coupling model for shock-induced laminar boundary-layer flows of a dust-laden gas and studies the transverse migration of fine particles under the action of Saffman lift force. The governing equations are formulated in the dilute twophase continuum framework with consideration of the finiteness of the particle Reynolds and Knudsen numbers. The full Lagrangian method is explored for calculating the dispersedphase flow fields (including the number density of particles) in the regions of intersecting particle trajectories. The computation results show a significant reaction of the particles on the two-phase boundary-layer structure when the mass loading ratio of particles takes finite values.展开更多
This paper presents the realization of two-way coupling of the unsaturated-saturated flow interactions of the SWAT2000 and MODFLOW96 models on the basis of the integrated surface/groundwater model SWATMOD99, and its a...This paper presents the realization of two-way coupling of the unsaturated-saturated flow interactions of the SWAT2000 and MODFLOW96 models on the basis of the integrated surface/groundwater model SWATMOD99, and its application in Hetao Irrigation District (HID), Inner Mongolia, China. Major revisions and enhancements were made to the SWAT2000 and MODFLOW models for simulating the detailed hydrologic budget and coupled unsaturated and saturated interactions, and irrigation canal hydrology for the HID. The simulation results of seasonal groundwater recharge to and evaporate from the shallow groundwater, and the annual water budget over the district are presented and discussed. The results implied the necessity of two-way coupling of the unsaturated-saturated interactions when groundwater is shallow, and the feasibility of making comprehensive use of the information coming from both the surface water and groundwater models to make a more physically-based assessment of the coupled interactions.展开更多
Multilayer structures composed of quasi-zero-stiffness(QZS)units exhibit mechanical characteristics distinct from those of a single unit,and their behaviors are governed by the coupling mechanism between the QZS units...Multilayer structures composed of quasi-zero-stiffness(QZS)units exhibit mechanical characteristics distinct from those of a single unit,and their behaviors are governed by the coupling mechanism between the QZS units.This paper introduces the coupling coefficient to quantitatively describe this mechanism,classifying the system into strongly coupled and weakly coupled states.Through theoretical analysis,numerical simulation,and experimental testing,the static and dynamic responses under different coupling states are comparatively investigated.The results show that in the strongly coupled system,the deformation behavior of each QZS unit shows high consistency,leading to a wider QZS region,weaker nonlinear characteristics,and stronger dynamic response.In the weakly coupled systems,the low degree of deformation coordinations among the units results in different QZS regions,enabling low-frequency vibration isolation under varying loads.The analytical approach of the coupling mechanisms and the static and dynamic response behaviors generated by the two coupling mechanisms provide guidance for the structural design of multifunctional and highly adaptable multi-level QZS metamaterials.展开更多
This study presents an effective hybrid simulation approach for simulating broadband ground motion in complex near-fault locations.The approach utilizes a deterministic approach based on the spectral element method(SE...This study presents an effective hybrid simulation approach for simulating broadband ground motion in complex near-fault locations.The approach utilizes a deterministic approach based on the spectral element method(SEM),which is used to simulate low-frequency ground motion(f1 Hz).A fourth-order Butterworth filter with zero phase shift is employed for time-domain filtering of low-and high-frequency time series at a crossover frequency of 1 Hz,merging the low and high-frequency ground motions into a broadband time series.Taking an Ms 6.8 Luding earthquake,as an example,this hybrid method was used for a rapid and efficient simulation analysis of broadband ground motion in the region.The accuracy and efficiency of this hybrid method were verified through comparisons with actually observed station data and empirical attenuation curves.Deterministic method simulation results revealed the effects of mountainous topography,basin effects,nonlinear effects within the basin’s sedimentary layers,and a coupling interaction between the basin and the mountains.The findings are consistent with similar studies,showing that near-fault sedimentary basins significantly focus and amplify strong ground motion,and the soil’s nonlinear behavior in the basin influences ground motion to varying extents at different distances from the fault.The mountainous topography impacts the basin’s response to ground motion,leading to barrier effects.This research provides a scientific foundation for seismic zoning,urban planning,and seismic design in nearfault mountain basin regions.展开更多
Based on the Smit-Suhl formula,we propose a universal approach for solving the magnon-magnon coupling problem in bilayer coupled systems(e.g.,antiferromagnets).This method requires only the energy expression,enabling ...Based on the Smit-Suhl formula,we propose a universal approach for solving the magnon-magnon coupling problem in bilayer coupled systems(e.g.,antiferromagnets).This method requires only the energy expression,enabling the automatic derivation of analytical expressions for the eigenmatrix elements via symbolic computation,eliminating the need for tedious manual calculations.Using this approach,we investigate the impact of magnetic hysteresis on magnon-magnon coupling in a system with interlayer Dzyaloshinskii-Moriya interaction(DMI).The magnetic hysteresis leads to an asymmetric magnetic field dependence of the resonance frequency and alters the number of degeneracy points between the pure optical and acoustic modes.Moreover,it can result in the coupling strength at the gap of the f–H phase diagram being nearly vanishing,contrary to the conventionally expected maximum.These results deepen the understanding of the effect of interlayer DMI on magnon–magnon coupling and the proposed universal method significantly streamlines the solving process of magnon–magnon coupling problems.展开更多
Platinum diselenide(PtSe2)exhibits a distinctive thickness-modulated semiconductor-to-semimetal transition,which makes it suitable for diverse applications in nanoelectronics and optoelectronics.This study systemat...Platinum diselenide(PtSe2)exhibits a distinctive thickness-modulated semiconductor-to-semimetal transition,which makes it suitable for diverse applications in nanoelectronics and optoelectronics.This study systematically investigates the spatiotemporal dynamics of photoexcited carrier relaxation in PtSe2.Through temperature-dependent ultrafast spectroscopy,two distinct low-frequency acoustic phonons(AP)were identified in multilayer PtSe2.Transient absorption microscopy(TAM)measurements reveal thickness-dependent relaxation dynamics and distinct carrier diffusion behavior in multilayer PtSe2.These findings indicate superior carrier transport properties,with a measured mobility of(394.1±38.5)cm2/(V·s)for multilayers.Temperature-dependent ultrafast dynamics,acquired using a custom-built cryogenic pump-probe system,reveal two coherent AP modes with central frequencies ofω1=1.27 THz andω2=0.17 THz,respectively.The higher frequencyω1mode corresponds to the shear mode with a nominal electron-phonon coupling constantλω1=2.22.This study,based on low-temperature ultrafast spectroscopy,elucidates the low-frequency acoustic phonon mode and strong electron-phonon coupling effect in the semimetal PtSe2.These findings lay the foundation for a deeper understanding of the semimetallic properties of PtSe2and for the design of ultrafast photonic devices.展开更多
Blast effects and energy transfer in near-ground explosions differ significantly from underground scenarios,particularly in terms of ground shock propagation and energy coupling mechanisms across various geological co...Blast effects and energy transfer in near-ground explosions differ significantly from underground scenarios,particularly in terms of ground shock propagation and energy coupling mechanisms across various geological conditions.This study employs centrifuge modeling to simulate near-ground explosions in sandy soil,including surface explosions and airbursts.The focus was on blast-induced cratering,ground shock effects,and energy coupling in sandy foundations.Scaling laws for crater dimensions and ground shock parameters were established and validated based on experimental results.The"modeling of models"series showed good consistency in crater measurements,leading to an empirical formula for estimating crater radius in dry sand.For surface explosions,soil acceleration responses showed single peaks in the central zone(horizontal standoff distance<0.6 m/(kg)1/3)and dual peaks in the near-surface zone(0.79-1.2 m/(kg)1/3)due to combined effects of direct and airburst-induced ground shock.Empirical methods were developed to predict peak acceleration distributions in sandy foundations.Utilizing crater measurements and ground shock propagation laws,a computational approach for evaluating energy transmission in soil foundations was proposed.The study also developed prediction curves for ground shock energy coupling coefficients with scaled blast depth/height,providing a unified model for both underground and near-ground explosions in sandy foundations.The research findings can enhance the methodologies for simulating blast effects and offer a scientific basis for optimizing weapon effectiveness and protective engineering design.展开更多
To accelerate the development and utilization of fusion energy,the China Fusion Engineering Test Reactor(CFETR)has been proposed as a bridge between the International Thermonuclear Experimental Reactor and demonstrati...To accelerate the development and utilization of fusion energy,the China Fusion Engineering Test Reactor(CFETR)has been proposed as a bridge between the International Thermonuclear Experimental Reactor and demonstration fusion reactors.The primary objective of the CFETR is to achieve fusion energy transformation and tritium self-sufficiency,which is realized through the function of the blanket.In this study,a neutronicshermal-hydraulics/mechanics coupling method is developed and applied to a helium-cooled ceramic breeder(HCCB)blanket,which is one of the two blanket candidates for the CFETR.A three-dimensional full-scale model is utilized in the coupling analysis to obtain the distributions of the neutronic,thermal-hydraulic,and mechanical parameters.A structural assessment of the CFETR HCCB blanket is then conducted considering steady-state conditions and two transient scenarios.The results demonstrate that following optimization of the blanket structure,the maximum temperatures of the different components remain below the safety limit of the corresponding materials.The structural assessment indicates that the blanket maintains its structural integrity under steady-state conditions.However,immediately after an in-box loss-of-coolant accident,structural failure owing to stress concentration may occur.Additionally,in the early stage of a loss-of-flow accident,the stress at the joint point between the cooling plate and cap exceeds the allowable stress of the material,potentially leading to structural failure within 17 s if no protective response is implemented.These findings provide comprehensive insights into the performance and safety of the CFETR HCCB blanket design.展开更多
A comprehensive full-sieve-hole grading correction method was used to adjust aggregate gradings.The fatigue properties of recycled concrete aggregate(RCA)asphalt mixtures were investigated using an improved indirect t...A comprehensive full-sieve-hole grading correction method was used to adjust aggregate gradings.The fatigue properties of recycled concrete aggregate(RCA)asphalt mixtures were investigated using an improved indirect tensile fatigue test under temperature-humidity coupling based on 20-year meteorological data of Beijing,and the degeneration mechanism was further explored by scanning electron microscopy and energy-dispersive spectroscopy.The experimental results indicate that replacing 5-20 mm coarse limestone aggregate(LA)with RCA at a 50% substitution volume can mitigate the impact of RCA variations on the asphalt mixture proportioning design.All RCA asphalt mixtures have lower initial fatigue properties than the LA asphalt mixture.However,under temperature-humidity coupling,the long-term fatigue property of an RCA asphalt mixture with a low proportion of recycled brick exceeds that of the LA asphalt mixture,and the fatigue life decline rate of the RCA asphalt mixture during 10-year service decreases by approximately 25%.This is due to the penetration of the asphalt mortar into the RCA through the pores and cracks on the RCA surface.It forms an interfacial transition zone composed of asphalt mortar and cement mortar and further reduces the mixture damage caused by the water and freeze-thaw conditions.展开更多
In deep coal mining,mine water containing acidic ions(Cl⁻,SO₄²⁻)often results in the saturation of coal over extended periods,causing physicochemical damage and compromising structural stability.The objective of ...In deep coal mining,mine water containing acidic ions(Cl⁻,SO₄²⁻)often results in the saturation of coal over extended periods,causing physicochemical damage and compromising structural stability.The objective of this study is to elucidate the instability mechanisms of coal subjected to compression-shear fracture in coupled hydrochemical-mechanical environments.Through uniaxial staged loading tests with variable shear angles(α=30°-70°),acoustic emission(AE)monitoring,scanning electron microscopy(SEM)characterization,and discrete element method(DEM),a systematical investigation was conducted to explore the damage evolution of coal saturated in neutral(pH=7)/weakly acidic(pH=5.5)conditions.The results indicate that both shear angles(α)and water chemistry significantly affect the damage evolution of coal.As the shear angle increases,the failure mode shifts from axial splitting to shear dominance,and the b-value decreases from 2.1 to 1.4.Weakly acidic conditions markedly accelerate the damage process,altering the energy release mode from gradual accumulation to sudden,concentrated release.Moment tensor analysis reveals that tensile sources are dominant at low α(45%).At the microscale,coal weakness is primarily induced by the selective dissolution of kaolinite,the formation of interfacial microcracks,and the loss of cementing material under acidic conditions.Based on the critical slowing down(CSD)theory,a precursory warning method focused on variance(S²)and the autocorrelation coefficient(φ)is proposed.These findings provide a theoretical basis for the risk assessment of dynamic disasters in mining and stratified prevention strategies for coal seams with different inclinations.展开更多
The thermal-hydraulic coupling processes in moraine soils containing frozen inclusions are prevalent in cold alpine regions(for example,the Tibetan Plateau)and closely linked to various mountainous geological hazards....The thermal-hydraulic coupling processes in moraine soils containing frozen inclusions are prevalent in cold alpine regions(for example,the Tibetan Plateau)and closely linked to various mountainous geological hazards.Despite extensive research,characterizing this coupling process remains challenging.This study investigates the evolution of the thermal-hydraulic properties of moraine soils containing frozen inclusions under warm water flow,considering key parameters and phase change.Parameter values were calibrated using field and laboratory data.The simulation results show the monotonic trend of outlet temperature,ice content and permeability.Thermal conductivity,soil porosity,fluid temperature,frozen inclusion content,and initial matrix permeability play predominant roles in the evolution process.Based on these findings,comprehensive models to quantitatively characterize the seepage evolution process were developed and discriminant models for two equilibrium states were established,incorporating critical factors.Furthermore,an in-depth discussion on the simulation of the phase-change process and the selection of the relative permeability range was provided.The findings enhance our understanding of thermal-hydraulic coupling processes in moraine soils and offer a valuable reference framework for future studies in this field.展开更多
Enhancing the nonconservative force exerted on the ferromagnetic material is a key strategy for improving magnetoelastic coupling in multiferroic composites.Inspired by the mechanism of pulsed lasers injecting phonons...Enhancing the nonconservative force exerted on the ferromagnetic material is a key strategy for improving magnetoelastic coupling in multiferroic composites.Inspired by the mechanism of pulsed lasers injecting phonons directly into ferromagnetic materials,we propose a method to introduce and amplify phonons by constructing a“phonon channel”.Analyzing the magnon excitation spectrum reveals that magnetoelastic coupling is significantly enhanced with an increasing amplification coefficient Apof nonconservative force in the phonon channel.When the external magnetic field is parallel to the wave vector of the spin wave,the amplitude of magnons in the anti-crossing region exhibits left-right symmetry with respect to the crossing point.In contrast,when the magnetic field is perpendicular,the symmetry becomes up-down.Introducing a coupling layer into the multiferroic composites provides a viable approach to realizing the phonon channel.Taking a multiferroic composite structure consisting of polyvinylidene fluoride and yttrium iron garnet as an example,we compare the electrical and acoustic properties of multiferroic composites with and without a coupling layer in the microwave frequency band.The enhancement of electrical and acoustic properties confirms the effectiveness of the phonon channel in multiferroic composites.展开更多
Global-and meso-scale dipolarizations are well-known features of Earth’s magnetosphere,but their coupling remains poorly understood.Here,using a new approach that combines two-dimentional(2D)ionospheric field-aligned...Global-and meso-scale dipolarizations are well-known features of Earth’s magnetosphere,but their coupling remains poorly understood.Here,using a new approach that combines two-dimentional(2D)ionospheric field-aligned current(FAC)maps with coordinated observations from a network of magnetospheric satellites,we directly show that individual global-scale dipolarizations can expand from the nightside to,or even into,the dayside.These expansions are enduring(20–30 minutes),slow(2–4 deg/min),and global in extent(up to 12 h in local time),consistent with previous statistical inferences but now explicitly observed.The expanding FACs form a two-sheet current system as described by the Boström II model.In contrast,meso-scale dipolarizations are bursty(a few minutes),fast(several tens deg/min),and localized(several hours in local time),as evidenced by auroral expansions and satellite data.They are associated with the line-current system as described by the Boström I model(i.e.,the substorm current wedge).Notably,meso-scale dipolarizations often emerge near the expanding edge of a global-scale dipolarization,suggesting a dynamic coupling between the two scales.These observations provide a complementary scenario to the simulation-based interpretation that global-scale dipolarizations result from the accumulation of meso-scale dipolarizations.Here,meso-scale dipolarizations appear far less frequently than in simulations and occur around the edge of global-scale dipolarizations.This result implies that meso-scale dipolarizations may be sporadically triggered during the azimuthal expansion of global-scale dipolarizations.展开更多
The use of Silane Coupling Agent(SCA)is an important way to improve the joining quality between metal and plastic.However,how to rationally use SCAs is still lack of guidance.We investigate the effect of type of SCA,s...The use of Silane Coupling Agent(SCA)is an important way to improve the joining quality between metal and plastic.However,how to rationally use SCAs is still lack of guidance.We investigate the effect of type of SCA,soaking time of SCA,and combination of SCA on the interfacial features and joint performance of ultrasonically welded AA6061 to CF/PA6.Four SCAs(γ-chloropropyltrimethoxysilane(NQ54),γ-chloropropyltriethoxysilane(KH230),vinyltrimethoxysilane(A171),γ-aminopropyltriethyloxysilane(KH550))were selected.The results show that the optimal joint strength(30.2 MPa)is obtained when the Al sheets are soaked in KH550 for 3 min.A fully dehydrated condensation reaction occurs between the OAH of the KH550 and the OAH on the aluminum alloy surface,forming plenty of Si AOAAl bonds,which contribute to the improved wetting behavior of liquid PA6 on the aluminum alloy surface.However,the combination of SCAs leads to the consumption of functional groups,hindering the formation of Si AOAAl bonds,and therefore reducing the joint performance.展开更多
High rock temperature is a great challenge frequently encountered during subsurface resource recovery and deep underground space utilization,and it is still unclear how the granitic rock responds to realtime high temp...High rock temperature is a great challenge frequently encountered during subsurface resource recovery and deep underground space utilization,and it is still unclear how the granitic rock responds to realtime high temperature upon shear loading.To better understand the shear fracture behavior and underlying processes of intact granite exposed to thermal-mechanical coupling loading,direct shear tests were conducted utilizing a newly built testing apparatus at varied normal stresses and high temperatures.Influencesof different temperatures and different heating methods(real-time heating and thermal treatment)on the shear mechanical behavior were compared and discussed.Results indicate that shear stress fluctuationswith some small stress drops occur as shear stress is approaching the peak strength under real-time heating,accompanied by more and earlier AE signal uprushes.This suggests that greater cracking events occur earlier during real-time heating than after thermal treatment,resulting in a lower peak shear strength.Furthermore,the peak shear strength,post-peak stress drop,and cohesion rise from room temperature(RT)to 200℃(the peak strength increases by 8%,5.8%,and 9.9%under normal stress of 5 MPa,15 MPa,and 20 MPa,correspondingly),and subsequently decline from 200℃to 400℃.Temperature has a limited impact on shear stiffness from RT to 200℃,but significantlyreduces it from 200℃to 400℃,with drops of 15%,7.9%,and 10%under normal stress of 5 MPa,15 MPa,and 20 MPa,respectively.Moreover,the shear strength and stiffness under real-time heating are lower than those for the thermally treated specimens.The strengthening of intact granite below 200℃upon shear is associated with loss of water and a more compacted structure,while the weakening effect of temperature on shear strength from 200℃to 400℃is due to the new thermal cracks and less brittle and stiff of minerals.展开更多
The accurate preforming modelling of 3D woven fabrics is essential for their forming quality control and optimization.However,their tension-shear coupling during preforming is not considered in the existing models.To ...The accurate preforming modelling of 3D woven fabrics is essential for their forming quality control and optimization.However,their tension-shear coupling during preforming is not considered in the existing models.To address this issue,an anisotropic hyperelastic constitutive model considering the tension-shear coupling was established for 3D woven fabrics.A picture frame tester was designed and manufactured to investigate tension-shear coupling effect.The results show that the fiber pre-tension can significantly enhance the shear resistance of 3D woven fabrics.The biaxial pre-tension of 1.5%can increase the in-plane shear force by up to 2.25 times compared to that in the pure in-plane shear.The identified tension-shear coupling parameters were integrated into the hyperelastic constitutive model and were implemented via user subroutine in Abaqus.The model’s effectiveness was verified by the hemispherical and fan blade forming experiments.The proposed coupled model demonstrates higher prediction accuracy than the uncoupled model in terms of shear angle and force,which provides a valuable tool for the optimization of forming process of 3D woven fabric.展开更多
There is a strong coupling relationship between the friction characteristics of the ball-groove interface and the ball motion behavior.However,available studies tend to consider ball motion and frictional behavior sep...There is a strong coupling relationship between the friction characteristics of the ball-groove interface and the ball motion behavior.However,available studies tend to consider ball motion and frictional behavior separately.In this paper,a unified tribology-kinematic model is established considering the coupling effect between friction and the ball velocity vector.The friction in ball-groove contact and ball speed are simultaneously measured by a newly developed disc-ball-disc device for studying friction and movement in ball screws.A comprehensive analysis of rubbing interface behavior and ball motion is conducted.The results show that the coupling effect between friction in ball-groove contact and ball motion is quite obvious.The sliding velocity of the ball is much higher with coupling effect than that when ignoring coupling influence,especially at high-speed conditions.The friction in ball-groove contact decreases at first and then shows a dramatic increase with the gradual rise of rotation speed,which is caused by the coupling variation of sliding speed.The studies show that the disc-ball-disc approach is an innovative and valuable method to investigate friction and ball motion in ball screws.展开更多
Tilt-to-length(TTL)coupling noise is a critical issue in space-based gravitational wave detection due to its complex dependence on multiple interacting factors,which complicates the identification of dominant paramete...Tilt-to-length(TTL)coupling noise is a critical issue in space-based gravitational wave detection due to its complex dependence on multiple interacting factors,which complicates the identification of dominant parameters.To address this challenge,we develop a simulation model of the Taiji scientific interferometer,generating noise datasets under multiparameter conditions.Given the uniqueness of the telescope as well as the convergence behavior of the algorithm,the analysis is structured hierarchically:(i)the telescope level and(ii)the optical bench level.A hierarchical framework combining XGBoost and SHapley Additive exPlanations(SHAP)values is employed to model the intricate relationships between parameters and TTL coupling noise,supplemented by sensitivity analysis.Our results identify pointing jitter and telescope radius as the dominant parameters at the telescope level,while the angles of the plane mirrors and beam splitters are most influential at the optical bench level.The parameter space is reduced from 86 dimensions to 14 dimensions without sacrificing model accuracy.This approach offers actionable insights for optimizing the Taiji interferometer design.展开更多
Photocatalytic oxidative coupling of methane(POCM)is a promising strategy for the production of sustainable C2+hydrocarbons;however,it typically relies on large quantities of noble metals,such as gold,to serve as a...Photocatalytic oxidative coupling of methane(POCM)is a promising strategy for the production of sustainable C2+hydrocarbons;however,it typically relies on large quantities of noble metals,such as gold,to serve as active sites for methyl coupling.In this study,we demonstrate that ZnO-supported gold nanoclusters with an average diameter of 1.1 nm provide a robust alternative to conventional gold nanoparticles,enabling efficient POCM even at ultralow gold loadings of 0.1 wt%.The optimized photocatalyst affords a C2–C4 hydrocarbon production rate of 3.89 mmol/(g h)with 94.8%selectivity under 365 nm irradiation in a batch reactor.Results reveal that the abundant interfaces between highly dispersed gold nanoclusters and ZnO substrates facilitate charge carrier separation and promote a light-induced Mars–van Krevelen reaction pathway.Methyl adsorption causes gold nanoclusters to exhibit a more intense d-σhybridization state compared to gold nanoparticles,enhancing electron transfer interactions and substantially reducing the transition-state energy barrier for methyl coupling.展开更多
基金The project supported by the National Natural Science Foundation of China(90205024)Russian Foundation for Basic Research(RFBR and(RFBR-NSFC-39004)
摘要The present paper describes a numerical two-way coupling model for shock-induced laminar boundary-layer flows of a dust-laden gas and studies the transverse migration of fine particles under the action of Saffman lift force. The governing equations are formulated in the dilute twophase continuum framework with consideration of the finiteness of the particle Reynolds and Knudsen numbers. The full Lagrangian method is explored for calculating the dispersedphase flow fields (including the number density of particles) in the regions of intersecting particle trajectories. The computation results show a significant reaction of the particles on the two-phase boundary-layer structure when the mass loading ratio of particles takes finite values.
基金supported by the National Basic Research Program of China (2010CB951002)the Knowledge Innovation Project of Chinese Academy of Sciences (KZXC2-YW-BR-12)
摘要This paper presents the realization of two-way coupling of the unsaturated-saturated flow interactions of the SWAT2000 and MODFLOW96 models on the basis of the integrated surface/groundwater model SWATMOD99, and its application in Hetao Irrigation District (HID), Inner Mongolia, China. Major revisions and enhancements were made to the SWAT2000 and MODFLOW models for simulating the detailed hydrologic budget and coupled unsaturated and saturated interactions, and irrigation canal hydrology for the HID. The simulation results of seasonal groundwater recharge to and evaporate from the shallow groundwater, and the annual water budget over the district are presented and discussed. The results implied the necessity of two-way coupling of the unsaturated-saturated interactions when groundwater is shallow, and the feasibility of making comprehensive use of the information coming from both the surface water and groundwater models to make a more physically-based assessment of the coupled interactions.
基金Project supported by the National Natural Science Foundation of China(No.52250287)。
摘要Multilayer structures composed of quasi-zero-stiffness(QZS)units exhibit mechanical characteristics distinct from those of a single unit,and their behaviors are governed by the coupling mechanism between the QZS units.This paper introduces the coupling coefficient to quantitatively describe this mechanism,classifying the system into strongly coupled and weakly coupled states.Through theoretical analysis,numerical simulation,and experimental testing,the static and dynamic responses under different coupling states are comparatively investigated.The results show that in the strongly coupled system,the deformation behavior of each QZS unit shows high consistency,leading to a wider QZS region,weaker nonlinear characteristics,and stronger dynamic response.In the weakly coupled systems,the low degree of deformation coordinations among the units results in different QZS regions,enabling low-frequency vibration isolation under varying loads.The analytical approach of the coupling mechanisms and the static and dynamic response behaviors generated by the two coupling mechanisms provide guidance for the structural design of multifunctional and highly adaptable multi-level QZS metamaterials.
基金National Natural Science Foundation of China under Grant Nos.U2139208 and 52278516Key Laboratory of Earthquake Engineering and Engineering Vibration,China Earthquake Administration under Grant No.2024D15Key Laboratory of Soft Soil Characteristic and Engineering Environment,Tianjin Chengjian University under Grant No.2022SCEEKL003。
摘要This study presents an effective hybrid simulation approach for simulating broadband ground motion in complex near-fault locations.The approach utilizes a deterministic approach based on the spectral element method(SEM),which is used to simulate low-frequency ground motion(f1 Hz).A fourth-order Butterworth filter with zero phase shift is employed for time-domain filtering of low-and high-frequency time series at a crossover frequency of 1 Hz,merging the low and high-frequency ground motions into a broadband time series.Taking an Ms 6.8 Luding earthquake,as an example,this hybrid method was used for a rapid and efficient simulation analysis of broadband ground motion in the region.The accuracy and efficiency of this hybrid method were verified through comparisons with actually observed station data and empirical attenuation curves.Deterministic method simulation results revealed the effects of mountainous topography,basin effects,nonlinear effects within the basin’s sedimentary layers,and a coupling interaction between the basin and the mountains.The findings are consistent with similar studies,showing that near-fault sedimentary basins significantly focus and amplify strong ground motion,and the soil’s nonlinear behavior in the basin influences ground motion to varying extents at different distances from the fault.The mountainous topography impacts the basin’s response to ground motion,leading to barrier effects.This research provides a scientific foundation for seismic zoning,urban planning,and seismic design in nearfault mountain basin regions.
基金supported by the National Key Research and Development Program of China (MOST)(Grant No.2022YFA1402800)the Chinese Academy of Sciences (CAS) Presidents International Fellowship Initiative (PIFI)(Grant No.2025PG0006)+3 种基金the National Natural Science Foundation of China (NSFC)(Grant Nos.51831012,12274437,and 52161160334)the CAS Project for Young Scientists in Basic Research (Grant No.YSBR-084)the CAS Youth Interdisciplinary Teamthe China Postdoctoral Science Foundation (Grant No.2025M773402)。
摘要Based on the Smit-Suhl formula,we propose a universal approach for solving the magnon-magnon coupling problem in bilayer coupled systems(e.g.,antiferromagnets).This method requires only the energy expression,enabling the automatic derivation of analytical expressions for the eigenmatrix elements via symbolic computation,eliminating the need for tedious manual calculations.Using this approach,we investigate the impact of magnetic hysteresis on magnon-magnon coupling in a system with interlayer Dzyaloshinskii-Moriya interaction(DMI).The magnetic hysteresis leads to an asymmetric magnetic field dependence of the resonance frequency and alters the number of degeneracy points between the pure optical and acoustic modes.Moreover,it can result in the coupling strength at the gap of the f–H phase diagram being nearly vanishing,contrary to the conventionally expected maximum.These results deepen the understanding of the effect of interlayer DMI on magnon–magnon coupling and the proposed universal method significantly streamlines the solving process of magnon–magnon coupling problems.
基金Projects(62275275,11904239)supported by the National Natural Science Foundation of ChinaProjects(2021JJ40709,2022JJ20080)supported by the Natural Science Foundation of Hunan Province,China+2 种基金Project(2022RC3068)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProject supported by the High Performance Computing Center of Central South University,ChinaProject supported by the Open Sharing Fund for the Large-scale Instruments and Equipment of Central South University,China。
摘要Platinum diselenide(PtSe2)exhibits a distinctive thickness-modulated semiconductor-to-semimetal transition,which makes it suitable for diverse applications in nanoelectronics and optoelectronics.This study systematically investigates the spatiotemporal dynamics of photoexcited carrier relaxation in PtSe2.Through temperature-dependent ultrafast spectroscopy,two distinct low-frequency acoustic phonons(AP)were identified in multilayer PtSe2.Transient absorption microscopy(TAM)measurements reveal thickness-dependent relaxation dynamics and distinct carrier diffusion behavior in multilayer PtSe2.These findings indicate superior carrier transport properties,with a measured mobility of(394.1±38.5)cm2/(V·s)for multilayers.Temperature-dependent ultrafast dynamics,acquired using a custom-built cryogenic pump-probe system,reveal two coherent AP modes with central frequencies ofω1=1.27 THz andω2=0.17 THz,respectively.The higher frequencyω1mode corresponds to the shear mode with a nominal electron-phonon coupling constantλω1=2.22.This study,based on low-temperature ultrafast spectroscopy,elucidates the low-frequency acoustic phonon mode and strong electron-phonon coupling effect in the semimetal PtSe2.These findings lay the foundation for a deeper understanding of the semimetallic properties of PtSe2and for the design of ultrafast photonic devices.
基金supported by the National Natural Science Foundation of China(Grant No.52588202)under the project''Multiphase Media Evolution in Hypergravity''.
摘要Blast effects and energy transfer in near-ground explosions differ significantly from underground scenarios,particularly in terms of ground shock propagation and energy coupling mechanisms across various geological conditions.This study employs centrifuge modeling to simulate near-ground explosions in sandy soil,including surface explosions and airbursts.The focus was on blast-induced cratering,ground shock effects,and energy coupling in sandy foundations.Scaling laws for crater dimensions and ground shock parameters were established and validated based on experimental results.The"modeling of models"series showed good consistency in crater measurements,leading to an empirical formula for estimating crater radius in dry sand.For surface explosions,soil acceleration responses showed single peaks in the central zone(horizontal standoff distance<0.6 m/(kg)1/3)and dual peaks in the near-surface zone(0.79-1.2 m/(kg)1/3)due to combined effects of direct and airburst-induced ground shock.Empirical methods were developed to predict peak acceleration distributions in sandy foundations.Utilizing crater measurements and ground shock propagation laws,a computational approach for evaluating energy transmission in soil foundations was proposed.The study also developed prediction curves for ground shock energy coupling coefficients with scaled blast depth/height,providing a unified model for both underground and near-ground explosions in sandy foundations.The research findings can enhance the methodologies for simulating blast effects and offer a scientific basis for optimizing weapon effectiveness and protective engineering design.
基金supported by the National Natural Science Foundation of China(Nos.12405194 and 52276052)the National Key R&D Program of China(Nos.2024YFE03230200 and 2022YFE03160002)the Natural Science Foundation of Chongqing,China(No.CSTB2025NSCQ-GPX0761)。
摘要To accelerate the development and utilization of fusion energy,the China Fusion Engineering Test Reactor(CFETR)has been proposed as a bridge between the International Thermonuclear Experimental Reactor and demonstration fusion reactors.The primary objective of the CFETR is to achieve fusion energy transformation and tritium self-sufficiency,which is realized through the function of the blanket.In this study,a neutronicshermal-hydraulics/mechanics coupling method is developed and applied to a helium-cooled ceramic breeder(HCCB)blanket,which is one of the two blanket candidates for the CFETR.A three-dimensional full-scale model is utilized in the coupling analysis to obtain the distributions of the neutronic,thermal-hydraulic,and mechanical parameters.A structural assessment of the CFETR HCCB blanket is then conducted considering steady-state conditions and two transient scenarios.The results demonstrate that following optimization of the blanket structure,the maximum temperatures of the different components remain below the safety limit of the corresponding materials.The structural assessment indicates that the blanket maintains its structural integrity under steady-state conditions.However,immediately after an in-box loss-of-coolant accident,structural failure owing to stress concentration may occur.Additionally,in the early stage of a loss-of-flow accident,the stress at the joint point between the cooling plate and cap exceeds the allowable stress of the material,potentially leading to structural failure within 17 s if no protective response is implemented.These findings provide comprehensive insights into the performance and safety of the CFETR HCCB blanket design.
基金Funded by"Green Construction and Maintenance of Road Engineering"the Belt and Road Joint Laboratory,International(Hong Kong,Macao and Taiwan)Science and Technology Cooperation Project(No.Z251100007125040)the National Key R&D Program of China(No.2022YFC3803403)+3 种基金the Project of Construction and Support for High-level Innovative Teams of Beijing Municipal Institutions(No.BPHR20220109)the Cultivation Project Funds for Beijing University of Civil Engineering and Architecture(No.X24013)the BUCEA Doctor Graduate Scientific Research Ability Improvement Project(No.DG2024016)the China Scholarship Council(No.202408110091)。
摘要A comprehensive full-sieve-hole grading correction method was used to adjust aggregate gradings.The fatigue properties of recycled concrete aggregate(RCA)asphalt mixtures were investigated using an improved indirect tensile fatigue test under temperature-humidity coupling based on 20-year meteorological data of Beijing,and the degeneration mechanism was further explored by scanning electron microscopy and energy-dispersive spectroscopy.The experimental results indicate that replacing 5-20 mm coarse limestone aggregate(LA)with RCA at a 50% substitution volume can mitigate the impact of RCA variations on the asphalt mixture proportioning design.All RCA asphalt mixtures have lower initial fatigue properties than the LA asphalt mixture.However,under temperature-humidity coupling,the long-term fatigue property of an RCA asphalt mixture with a low proportion of recycled brick exceeds that of the LA asphalt mixture,and the fatigue life decline rate of the RCA asphalt mixture during 10-year service decreases by approximately 25%.This is due to the penetration of the asphalt mortar into the RCA through the pores and cracks on the RCA surface.It forms an interfacial transition zone composed of asphalt mortar and cement mortar and further reduces the mixture damage caused by the water and freeze-thaw conditions.
基金financially supported by the National Natural Science Foundation of China(Grant No.52374241).
摘要In deep coal mining,mine water containing acidic ions(Cl⁻,SO₄²⁻)often results in the saturation of coal over extended periods,causing physicochemical damage and compromising structural stability.The objective of this study is to elucidate the instability mechanisms of coal subjected to compression-shear fracture in coupled hydrochemical-mechanical environments.Through uniaxial staged loading tests with variable shear angles(α=30°-70°),acoustic emission(AE)monitoring,scanning electron microscopy(SEM)characterization,and discrete element method(DEM),a systematical investigation was conducted to explore the damage evolution of coal saturated in neutral(pH=7)/weakly acidic(pH=5.5)conditions.The results indicate that both shear angles(α)and water chemistry significantly affect the damage evolution of coal.As the shear angle increases,the failure mode shifts from axial splitting to shear dominance,and the b-value decreases from 2.1 to 1.4.Weakly acidic conditions markedly accelerate the damage process,altering the energy release mode from gradual accumulation to sudden,concentrated release.Moment tensor analysis reveals that tensile sources are dominant at low α(45%).At the microscale,coal weakness is primarily induced by the selective dissolution of kaolinite,the formation of interfacial microcracks,and the loss of cementing material under acidic conditions.Based on the critical slowing down(CSD)theory,a precursory warning method focused on variance(S²)and the autocorrelation coefficient(φ)is proposed.These findings provide a theoretical basis for the risk assessment of dynamic disasters in mining and stratified prevention strategies for coal seams with different inclinations.
基金supported by the National Natural Science Foundation of China(42090054)the Natural Science Foundation of Hubei Province of China(2022CFA002 and 2024AFD358).
摘要The thermal-hydraulic coupling processes in moraine soils containing frozen inclusions are prevalent in cold alpine regions(for example,the Tibetan Plateau)and closely linked to various mountainous geological hazards.Despite extensive research,characterizing this coupling process remains challenging.This study investigates the evolution of the thermal-hydraulic properties of moraine soils containing frozen inclusions under warm water flow,considering key parameters and phase change.Parameter values were calibrated using field and laboratory data.The simulation results show the monotonic trend of outlet temperature,ice content and permeability.Thermal conductivity,soil porosity,fluid temperature,frozen inclusion content,and initial matrix permeability play predominant roles in the evolution process.Based on these findings,comprehensive models to quantitatively characterize the seepage evolution process were developed and discriminant models for two equilibrium states were established,incorporating critical factors.Furthermore,an in-depth discussion on the simulation of the phase-change process and the selection of the relative permeability range was provided.The findings enhance our understanding of thermal-hydraulic coupling processes in moraine soils and offer a valuable reference framework for future studies in this field.
基金supported by the National Key Research and Development Program of China(Garnt No.2021YFA0716500)the China Postdoctoral Science Foundation(Grant No.2024M753738)+1 种基金the Shenzhen Science and Technology Program(Grant Nos.JCYJ20210324123202008 and JCYJ20210324115412035)the Basic and Applied Basic Research Program of Guangdong Province(Grant Nos.2021A1515110880 and 2023A1515012752)。
摘要Enhancing the nonconservative force exerted on the ferromagnetic material is a key strategy for improving magnetoelastic coupling in multiferroic composites.Inspired by the mechanism of pulsed lasers injecting phonons directly into ferromagnetic materials,we propose a method to introduce and amplify phonons by constructing a“phonon channel”.Analyzing the magnon excitation spectrum reveals that magnetoelastic coupling is significantly enhanced with an increasing amplification coefficient Apof nonconservative force in the phonon channel.When the external magnetic field is parallel to the wave vector of the spin wave,the amplitude of magnons in the anti-crossing region exhibits left-right symmetry with respect to the crossing point.In contrast,when the magnetic field is perpendicular,the symmetry becomes up-down.Introducing a coupling layer into the multiferroic composites provides a viable approach to realizing the phonon channel.Taking a multiferroic composite structure consisting of polyvinylidene fluoride and yttrium iron garnet as an example,we compare the electrical and acoustic properties of multiferroic composites with and without a coupling layer in the microwave frequency band.The enhancement of electrical and acoustic properties confirms the effectiveness of the phonon channel in multiferroic composites.
基金NASA(National Aeronautics and Space Administration)grant 81NSSC19K0306NASA prime contract NAS5-01072+6 种基金AFOSR(Air Force Office of Scientific Research)grant FA9559-16-1-0364NSF(National Science Foundation)grant AGS-2055192NASA grants 80NSSC20K1314,80NSSC20K1316,and 80NSSC21K1407NASA Contract NAS5-02099NASA grants:80NSSC18K1220 and 80NSSC18K0570NASA contracts 80GSFC17C0018,and NAS5-02099NASA award 80NSSC18K1227。
摘要Global-and meso-scale dipolarizations are well-known features of Earth’s magnetosphere,but their coupling remains poorly understood.Here,using a new approach that combines two-dimentional(2D)ionospheric field-aligned current(FAC)maps with coordinated observations from a network of magnetospheric satellites,we directly show that individual global-scale dipolarizations can expand from the nightside to,or even into,the dayside.These expansions are enduring(20–30 minutes),slow(2–4 deg/min),and global in extent(up to 12 h in local time),consistent with previous statistical inferences but now explicitly observed.The expanding FACs form a two-sheet current system as described by the Boström II model.In contrast,meso-scale dipolarizations are bursty(a few minutes),fast(several tens deg/min),and localized(several hours in local time),as evidenced by auroral expansions and satellite data.They are associated with the line-current system as described by the Boström I model(i.e.,the substorm current wedge).Notably,meso-scale dipolarizations often emerge near the expanding edge of a global-scale dipolarization,suggesting a dynamic coupling between the two scales.These observations provide a complementary scenario to the simulation-based interpretation that global-scale dipolarizations result from the accumulation of meso-scale dipolarizations.Here,meso-scale dipolarizations appear far less frequently than in simulations and occur around the edge of global-scale dipolarizations.This result implies that meso-scale dipolarizations may be sporadically triggered during the azimuthal expansion of global-scale dipolarizations.
基金supported by the National Natural Science Foundation of China(No.52075375)。
摘要The use of Silane Coupling Agent(SCA)is an important way to improve the joining quality between metal and plastic.However,how to rationally use SCAs is still lack of guidance.We investigate the effect of type of SCA,soaking time of SCA,and combination of SCA on the interfacial features and joint performance of ultrasonically welded AA6061 to CF/PA6.Four SCAs(γ-chloropropyltrimethoxysilane(NQ54),γ-chloropropyltriethoxysilane(KH230),vinyltrimethoxysilane(A171),γ-aminopropyltriethyloxysilane(KH550))were selected.The results show that the optimal joint strength(30.2 MPa)is obtained when the Al sheets are soaked in KH550 for 3 min.A fully dehydrated condensation reaction occurs between the OAH of the KH550 and the OAH on the aluminum alloy surface,forming plenty of Si AOAAl bonds,which contribute to the improved wetting behavior of liquid PA6 on the aluminum alloy surface.However,the combination of SCAs leads to the consumption of functional groups,hindering the formation of Si AOAAl bonds,and therefore reducing the joint performance.
基金support from the Taishan Scholars Program,Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS),Grant No.ZDBS-LY-DQC022Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Grant No.SKLGME023003.
摘要High rock temperature is a great challenge frequently encountered during subsurface resource recovery and deep underground space utilization,and it is still unclear how the granitic rock responds to realtime high temperature upon shear loading.To better understand the shear fracture behavior and underlying processes of intact granite exposed to thermal-mechanical coupling loading,direct shear tests were conducted utilizing a newly built testing apparatus at varied normal stresses and high temperatures.Influencesof different temperatures and different heating methods(real-time heating and thermal treatment)on the shear mechanical behavior were compared and discussed.Results indicate that shear stress fluctuationswith some small stress drops occur as shear stress is approaching the peak strength under real-time heating,accompanied by more and earlier AE signal uprushes.This suggests that greater cracking events occur earlier during real-time heating than after thermal treatment,resulting in a lower peak shear strength.Furthermore,the peak shear strength,post-peak stress drop,and cohesion rise from room temperature(RT)to 200℃(the peak strength increases by 8%,5.8%,and 9.9%under normal stress of 5 MPa,15 MPa,and 20 MPa,correspondingly),and subsequently decline from 200℃to 400℃.Temperature has a limited impact on shear stiffness from RT to 200℃,but significantlyreduces it from 200℃to 400℃,with drops of 15%,7.9%,and 10%under normal stress of 5 MPa,15 MPa,and 20 MPa,respectively.Moreover,the shear strength and stiffness under real-time heating are lower than those for the thermally treated specimens.The strengthening of intact granite below 200℃upon shear is associated with loss of water and a more compacted structure,while the weakening effect of temperature on shear strength from 200℃to 400℃is due to the new thermal cracks and less brittle and stiff of minerals.
基金financially supported by the Aeronautical Science Foundation of China(No.2020Z068053001)the National Natural Science Foundation of China(Nos.12302191,52375383)the AECC Independent Innovation Special Fund Project,China(No.ZZCX-2021-022).
摘要The accurate preforming modelling of 3D woven fabrics is essential for their forming quality control and optimization.However,their tension-shear coupling during preforming is not considered in the existing models.To address this issue,an anisotropic hyperelastic constitutive model considering the tension-shear coupling was established for 3D woven fabrics.A picture frame tester was designed and manufactured to investigate tension-shear coupling effect.The results show that the fiber pre-tension can significantly enhance the shear resistance of 3D woven fabrics.The biaxial pre-tension of 1.5%can increase the in-plane shear force by up to 2.25 times compared to that in the pure in-plane shear.The identified tension-shear coupling parameters were integrated into the hyperelastic constitutive model and were implemented via user subroutine in Abaqus.The model’s effectiveness was verified by the hemispherical and fan blade forming experiments.The proposed coupled model demonstrates higher prediction accuracy than the uncoupled model in terms of shear angle and force,which provides a valuable tool for the optimization of forming process of 3D woven fabric.
基金Supported by National Natural Science Foundation of China(Grant No.52275206).
摘要There is a strong coupling relationship between the friction characteristics of the ball-groove interface and the ball motion behavior.However,available studies tend to consider ball motion and frictional behavior separately.In this paper,a unified tribology-kinematic model is established considering the coupling effect between friction and the ball velocity vector.The friction in ball-groove contact and ball speed are simultaneously measured by a newly developed disc-ball-disc device for studying friction and movement in ball screws.A comprehensive analysis of rubbing interface behavior and ball motion is conducted.The results show that the coupling effect between friction in ball-groove contact and ball motion is quite obvious.The sliding velocity of the ball is much higher with coupling effect than that when ignoring coupling influence,especially at high-speed conditions.The friction in ball-groove contact decreases at first and then shows a dramatic increase with the gradual rise of rotation speed,which is caused by the coupling variation of sliding speed.The studies show that the disc-ball-disc approach is an innovative and valuable method to investigate friction and ball motion in ball screws.
基金Project supported by the National Key Research and Development Program of China(Grant No.2020YFC2200100)the CAS's Strategic Pioneer Program on Space Science(Grant No.XDA1502110201)。
摘要Tilt-to-length(TTL)coupling noise is a critical issue in space-based gravitational wave detection due to its complex dependence on multiple interacting factors,which complicates the identification of dominant parameters.To address this challenge,we develop a simulation model of the Taiji scientific interferometer,generating noise datasets under multiparameter conditions.Given the uniqueness of the telescope as well as the convergence behavior of the algorithm,the analysis is structured hierarchically:(i)the telescope level and(ii)the optical bench level.A hierarchical framework combining XGBoost and SHapley Additive exPlanations(SHAP)values is employed to model the intricate relationships between parameters and TTL coupling noise,supplemented by sensitivity analysis.Our results identify pointing jitter and telescope radius as the dominant parameters at the telescope level,while the angles of the plane mirrors and beam splitters are most influential at the optical bench level.The parameter space is reduced from 86 dimensions to 14 dimensions without sacrificing model accuracy.This approach offers actionable insights for optimizing the Taiji interferometer design.
基金financial support from the National Key R&D Program of China(No.2023YFA1507201)the National Natural Science Foundation of China(Nos.22421005,52120105002,52432006,22272190,and 22088102)+2 种基金the CAS Project for Young Scientists in Basic Research(No.YSBR-004)the Liaoning Binhai Laboratory(No.LBLD-2024-06)the Young Elite Scientist Sponsorship Program by CAST(No.2021QNRC001).
摘要Photocatalytic oxidative coupling of methane(POCM)is a promising strategy for the production of sustainable C2+hydrocarbons;however,it typically relies on large quantities of noble metals,such as gold,to serve as active sites for methyl coupling.In this study,we demonstrate that ZnO-supported gold nanoclusters with an average diameter of 1.1 nm provide a robust alternative to conventional gold nanoparticles,enabling efficient POCM even at ultralow gold loadings of 0.1 wt%.The optimized photocatalyst affords a C2–C4 hydrocarbon production rate of 3.89 mmol/(g h)with 94.8%selectivity under 365 nm irradiation in a batch reactor.Results reveal that the abundant interfaces between highly dispersed gold nanoclusters and ZnO substrates facilitate charge carrier separation and promote a light-induced Mars–van Krevelen reaction pathway.Methyl adsorption causes gold nanoclusters to exhibit a more intense d-σhybridization state compared to gold nanoparticles,enhancing electron transfer interactions and substantially reducing the transition-state energy barrier for methyl coupling.