Backfill is often employed in mining operations for ground support,with its positive impact on ground stability acknowledged in many underground mines.However,existing studies have predominantly focused only on the st...Backfill is often employed in mining operations for ground support,with its positive impact on ground stability acknowledged in many underground mines.However,existing studies have predominantly focused only on the stress development within the backfill material,leaving the influence of stope backfilling on stress distribution in surrounding rock mass and ground stability largely unexplored.Therefore,this paper presents numerical models in FLAC3D to investigate,for the first time,the time-dependent stress redistribution around a vertical backfilled stope and its implications on ground stability,considering the creep of surrounding rock mass.Using the Soft Soil constitutive model,the compressibility of backfill under large pressure was captured.It is found that the creep deformation of rock mass exercises compression on backfill and results in a less void ratio and increased modulus for fill material.The compacted backfill conversely influenced the stress distribution and ground stability of rock mass which was a combined effect of wall creep and compressibility of backfill.With the increase of time or/and creep deformation,the minimum principal stress in the rocks surrounding the backfilled stope increased towards the pre-mining stress state,while the deviatoric stress reduces leading to an increased factor of safety and improved ground stability.This improvement effect of backfill on ground stability increased with the increase of mine depth and stope height,while it is also more pronounced for the narrow stope,the backfill with a smaller compression index,and the soft rocks with a smaller viscosity coefficient.Furthermore,the results emphasize the importance of minimizing empty time and backfilling extracted stope as soon as possible for ground control.Reduction of filling gap height enhances the local stability around the roof of stope.展开更多
Low-cost Fe-based disordered rock salt(DRX)Li_(2)FeTiO_(4)is capable of providing high capacity(295 mA h g^(-1))by redox activity of cations(Fe^(2+)/Fe^(4+)and Ti^(3+)/Ti^(4+))and anionic oxygen.However,DRX structures...Low-cost Fe-based disordered rock salt(DRX)Li_(2)FeTiO_(4)is capable of providing high capacity(295 mA h g^(-1))by redox activity of cations(Fe^(2+)/Fe^(4+)and Ti^(3+)/Ti^(4+))and anionic oxygen.However,DRX structures lack transport channels for ions and electrons,resulting in sluggish kinetics,poor electrochemical activity,and cyclability.Herein,graphene conductive carbon network permeated Li_(2)FeTiO_(4)(LFT/C/G)nanofibers are successfully prepared by a facile sol-gel assisted electrospinning method.Ultrafine Li_(2)FeTiO_(4)nanoparticles(2 nm)and one-dimensional(1D)structure provide abu ndant active sites and unobstructed diffu sion channels,accelerating ion diffusion.In addition,introducing graphene reduces the band gap and Li^(+)diffusion barrier and improves the dynamic properties of Li_(2)FeTiO_(4),thus achieving a relatively mild interfacial reaction and reversible redox reaction.As expected,the LFT/C/1.0G cathode delivers a remarkable discharge capacity(238.5 mA h g^(-1)),high energy density(508.8 Wh kg^(-1)),and excellent rate capability(51.2 mA hg^(-1)at 1.0 A g^(-1)).Besides,the LFT/C/1.0G anode also displays a high capacity(514.5 mA h g^(-1)at 500 mA g^(-1))and a remarkable rate capability(243.9 mA h g^(-1)at 8 A g^(-1)).Moreover,the full batteries based on the LFT/C/1.0G symmetric electrode demonstrate a reversible capacity of 117.0 mA h g^(-1)after 100 cycles at 50 mA g^(-1).This study presents useful insights into developing cost-effective DRX cathodes with durable and fast lithium storage.展开更多
The low damage resistance and fracture toughness hinder the widespread application of ultrahighstrength dual phase(DP)steels.In this work,we propose a novel strategy to improve the fracture toughness of ultrahigh-stre...The low damage resistance and fracture toughness hinder the widespread application of ultrahighstrength dual phase(DP)steels.In this work,we propose a novel strategy to improve the fracture toughness of ultrahigh-strength DP steels by an order of magnitude without sacrificing the tensile strength.Six ultrahigh-strength DP steels with varying microstructure but comparable tensile strength(>1400 MPa)were prepared via tailoring the heat treatment process after cold rolling.Additionally,finite element(FE)method incorporated with Gurson-Tvergaad-Needleman(GTN)model and cohesive zone model(CZM)is established to simulate the fracture behavior of DP steel.Twelve model DP steels with different ferrite sizes and F/M strength differences are constructed.The combined experiment and simulation results demonstrate that(i)ferrite/martensite(F/M)interface decohesion prevails in all steels,(ii)the ferrite morphology has a strong influence on the fracture toughness of ultrahigh-strength DP steels,(iii)the effects of matrix type,ferrite size,and F/M hardness difference on the fracture toughness are relatively weak,(iv)the exceptional high fracture toughness of plate-like DP steel can be attributed to the crack deflection,crack divider and crack arrester mechanisms induced by F/M interface decohesion.展开更多
The Northeast Plain in China ranks among the top five regions that have been significantly impacted by haze pollution.To effectively control pollution,it is crucial to accurately assess the effects of emission reducti...The Northeast Plain in China ranks among the top five regions that have been significantly impacted by haze pollution.To effectively control pollution,it is crucial to accurately assess the effects of emission reduction measures.In this study,we analyzed surveillance data and found substantial decreases(ranging from 19.0%to 50.1%)in average annual mass concentrations of key pollutants(such as CO,SO_(2),NO_(2),and PM_(2.5))in the Northeast Plain from 2016 to 2020.To precisely determine the contributions of meteorological conditions and emission reductions to the improvement of air quality in the Northeast Plain,we conducted three scenario simulations.By comparing source emissions in December 2016 and 2020 using the WRF-Chem model(except for SO_(2)),we observed significant reductions of 21.3%,8.8%,and 9.8%in mass concentrations of PM_(2.5),NO_(2),and CO,respectively,from 2016 to 2020.This highlights the essential role that meteorological conditions play in determining air quality in the Northeast Plain.Moreover,further reducing source emissions by 30%in December 2016 resulted in subsequent reductions of 25.3%,29.0%,4.5%,and 30.3%in mass concentrations of PM_(2.5),SO_(2),NO_(2),and CO,respectively,under the same meteorological conditions.Notably,source emission reduction was effective for PM_(2.5),SO_(2),and CO,but not for NO_(2).The improvement in air quality in the Northeast Plain from 2016 to 2020 can be attributed to the combined effects of improved meteorological conditions and reduced pollution sources.展开更多
The adsorption-catalysis ability of metal-based catalysts toward lithium polysulfides(LiPSs)is dominated by the position of their d-/p-band center.An available strategy to strengthen the d-p band center proximity of m...The adsorption-catalysis ability of metal-based catalysts toward lithium polysulfides(LiPSs)is dominated by the position of their d-/p-band center.An available strategy to strengthen the d-p band center proximity of metal-based catalysts is to fabricate a crystalline-amorphous heterointerface,which markedly enhances LiPS conversion.The polyanionic pyrophosphate of TiP_(2)O_(7)serves as an efficient catalyst and ionic conductor for lithium-sulfur(Li-S)batteries.However,TiP_(2)O_(7)does not fully optimize sulfur redox reactivity due to limitations in factors such as the adsorption-catalysis of sulfur species,Li^(+)diffusion,and electron transfer.Herein,we engineer the crystalline-amorphous heterointerface of TiP_(2)O_(7)combined with carbon nanotubes(CNTs)to facilitate electronic donation from C to TiP_(2)O_(7).This interaction results in an upward shift of the Ti d,enhancing the proximity of the d-p band center in TiP_(2)O_(7)/CNTs.By utilizing TiP_(2)O_(7)/CNTs as both electrode and separator modifier,we optimize the LiPS conversion process,showing a comprehensive strategy to mitigate the diffusion of LiPSs and achieve the bidirectional redox reactions in Li-S batteries.Accordingly,the cell assembled by TiP_(2)O_(7)/CNTs delivers a satisfactory capacity of835 mAh g^(-1)after 300 cycles at 4 C and an impressive initial areal capacity of 3.52 mAh cm^(-2)under the sulfur areal loading of 5 mg cm^(-2)at 0.1 C.Additionally,the Li//Li cells utilizing TiP_(2)O_(7)/CNTs present a prolonged cycling life of up to 1800 h without voltage fluctuation and Li dendrite growth.展开更多
Symmetric secondary batteries are expected to become promising storage devices on account of their low cost,environmentally friendly and high safety.Nevertheless,the further development of symmetric batteries needs to...Symmetric secondary batteries are expected to become promising storage devices on account of their low cost,environmentally friendly and high safety.Nevertheless,the further development of symmetric batteries needs to rely on bipolar electrodes with superior performance.Cation-disordered rocksalt(DRX)Li_(2)FeTiO_(4)shows promising properties as symmetric electrodes,based on the ability of iron to undergo multiple electrochemical reactions over a wide voltage window.Unfortunately,this cation-disordered structure would not provide a cross-path for the rapid migration of Li^(+),ultimately resulting in inferior electrochemical dynamics and cycle stability.Herein,Li_(2)FeTiO_(4)nanoparticles assembled by ultrafine nanocrystals are synthesized via a sol-gel method through an orderly reaction regulation strategy of precursor reactants.Such ultrafine nanocrystals increase the active sites to promote the reversibility of multi-cationic(e.g.,stable Fe^(2+)/Fe^(3+),Ti^(3+)/Ti^(4+)and moderated Fe^(3+)/Fe^(4+))and anionic redox,and maintain the DRX structure well during the cycling process.The half cells with nano-sized Li_(2)FeTiO_(4)as the cathode/anode exhibit a high reversible capacity of 127.8/500.8 mAh/g,respectively.Besides,the Li_(2)FeTiO_(4)//Li_(2)FeTiO_(4)symmetric full cell could provide a reversible capacity of 95.4 mAh/g at 0.1 A/g after 200 cycles.This hierarchical self-assembly by nanocrystal strategy could offer effective guidance for high-performance electrode design for rechargeable secondary batteries.展开更多
Si,as the most promising anode with high theoretical capacity for next-generation lithium-ion batteries(LIBs),is hampered in commercial application by its poor electrical conductivity and significant volume expansion....Si,as the most promising anode with high theoretical capacity for next-generation lithium-ion batteries(LIBs),is hampered in commercial application by its poor electrical conductivity and significant volume expansion.Herein,the core-shell Si@SiO_(x)/C@C-Ar(SSC-A)or Si@SiO_(x)/C@C-H_(2)/Ar(SSC-H)composites are purposefully designed by in situ introduction of inorganic SiO_(x)in pure Ar or H_(2)/Ar atmosphere to realize a Si-based anode for LIBs.By introducing different atmospheres,the valence states of SiO_(x)are regulated.The inorganic transition layer formed by the combination of SiO_(x)with higher average valence and asphalt-derived carbon demonstrates better performance in both stabilizing the core-shell structure and inhibiting the agglomeration of Si particles.Given these advantages,the SSC-A electrode exhibits excellent electrochemical performance(1163 mAh g^(-1)after 400 cycles at 1 A g^(-1)),and the commercial blended graphite-SSC-A electrode reaches a specific capacity of 442 mAh g^(-1)with 74.8%capacity retention under the same conditions.Even the SSC-A electrode without Super P maintains an ultrahigh discharge specific capacity of 803 mAh g^(-1)with 60.6%after cycling.Importantly,the full batteries based on SSC-A without Super P achieve a discharge specific capacity of 126 mAh g^(-1)with 28.2%capacity decay after 200 cycles,demonstrating the superior commercial application potential.展开更多
The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical r...The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures(573,583,and 593 K),but the limiting step is controlled by boundary layer diffusion at high temperatures(603 and 613 K).The Se-and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens,with Kirkendall voids generating in the product layer accelerating PbTe particle erosion.After the PbTe impurities in the selenium melt evolve into PbSe and Te,Te is evenly distributed in the selenium melt owing to the solubility of Se and Te.This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.展开更多
The authors regret that in the paper of Xin et al.(2024),a bug was found in the used numerical implementation.It concerns one of the damage coefficient that was incorrectly updated during the calculation process.As a ...The authors regret that in the paper of Xin et al.(2024),a bug was found in the used numerical implementation.It concerns one of the damage coefficient that was incorrectly updated during the calculation process.As a consequence for some fluctuation scales,the bug had a limited impact on the found constitutive model.Therefore,the conclusions given in the paper are still valid.The authors have re-analyzed all the constitutive model results presented in the paper and the corrected Table 9,Eqs.(19)and(20),and Fig.18 in the original paper are shown as follows.展开更多
To investigate the impact of emission controls on ammonia(NH_(3)) pollution in urban atmosphere, observation on NH_(3)(1 hr interval) was performed in Shanghai before, during and after the 2019 China International Imp...To investigate the impact of emission controls on ammonia(NH_(3)) pollution in urban atmosphere, observation on NH_(3)(1 hr interval) was performed in Shanghai before, during and after the 2019 China International Import Expo (CIIE) event, along with measurements on inorganic ions, organic tracers and stable nitrogen isotope compositions of ammonium in PM_(2.5). NH_(3)during the CIIE period was 6.5±1.0μg/m^(3), which is 41% and 32% lower than that before and after the event, respectively. Such a decrease was largely ascribed to the emission controls in nonagricultural sources, of which contribution for measured NH_(3)in control phase abated by ~20% compared to that during uncontrol period. Molecular compositions of PAHs and hopanes further suggested a dominant role of the reduced vehicle emissions in the urban NH_(3)abatement during the CIIE period. Our results revealed that vehicle exhaust emission control is an effective way to mitigate NH_(3)pollution and improve air quality in Chinese urban areas.展开更多
To understand the characteristics of atmospheric brown carbon(BrC),daily PM2.5 samples in Xingtai,a small city in North China Plain(NCP),during the four seasons of 2018-2019,were collected and analyzed for optical pro...To understand the characteristics of atmospheric brown carbon(BrC),daily PM2.5 samples in Xingtai,a small city in North China Plain(NCP),during the four seasons of 2018-2019,were collected and analyzed for optical properties and chemical compositions.The light absorption at 365 nm(abs λ=365 nm)displayed a strong seasonal variation with the highest value in winter(29.0±14.3 M/m),which was 3.2∼5.4-fold of that in other seasons.A strong correlation of abs λ=365 nm with benzo(b)fluoranthene(BbF)was only observed in winter,indicating that coal combustion was the major source for BrC in the season due to the enhanced domestic heating.The mass absorbing efficiency of BrC also exhibited a similar seasonal pattern,and was found to correlate linearly with the aerosol pH,suggesting a positive effect of aerosol acidity on the optical properties and formation of BrC in the city.Positive matrix factorization(PMF)analysis further showed that on a yearly basis the major source for BrC was biomass burning,which accounted for 34% of the total BrC,followed by secondary formation(26.7%),coal combustion(21.3%)and fugitive dust(18%).However,the contribution from coal combustionwas remarkably enhanced in winter,accounting for∼40%of the total.Our work revealed that more efforts of“shifting coal to clean energy”are necessary in rural areas and small cities in NCP in order to further mitigate PM2.5 pollution in China.展开更多
To investigate the composition and possible sources of particles, especially during heavy haze pollution, a single particle aerosol mass spectrometer（SPAMS） was deployed to measure the changes of single particle spe...To investigate the composition and possible sources of particles, especially during heavy haze pollution, a single particle aerosol mass spectrometer（SPAMS） was deployed to measure the changes of single particle species and sizes during October of 2014, in Beijing. A total of 2,871,431 particles with both positive and negative spectra were collected and characterized in combination with the adaptive resonance theory neural network algorithm（ART-2a）. Eight types of particles were classified： dust particles（dust, 8.1%）, elemental carbon（EC, 29.0%）, organic carbon（OC, 18.0%）, EC and OC combined particles（ECOC, 9.5%）,Na-K containing particles（Na K, 7.9%）, K-containing particles（K, 21.8%）, organic nitrogen and potassium containing particles（KCN, 2.3%）, and metal-containing particles（metal,3.6%）. Three haze pollution events（P1, P2, P3） and one clean period（clean） were analyzed,based on the mass and number concentration of PM_（2.5）and the back trajectory results from the hybrid single particle Lagrangian integrated trajectory model（Hysplit-4 model）. Results showed that EC, OC and K were the major components of single particles during the three haze pollution periods, which showed clearly increased ratios compared with those in the clean period. Results from the mixing state of secondary species of different types of particles showed that sulfate and nitrate were more readily mixed with carbon-containing particles during haze pollution episodes than in clean periods.展开更多
Several special mechanical properties,such as dilatancy and compressibility,of cemented paste backfill(CPB)are controlled by its internal microstructure and evolution.The mesoscopic structure changes of CPB during the...Several special mechanical properties,such as dilatancy and compressibility,of cemented paste backfill(CPB)are controlled by its internal microstructure and evolution.The mesoscopic structure changes of CPB during the development process were investigated.On the basis of the scanning electron microscopy(SEM)and mechanical test results of CPB,the particle size information of CPB was extracted,and a two-dimensional particle flow code(PFC)model of CPB was established to analyze the evolution rule of mesoscopic parameters during CPB development.The embedded FISH language in PFC was used to develop a program for establishing a PFC model on the basis of the SEM results.The mesoscopic parameters of CPB samples at different curing times,such as coordination number(C_(n)),contact force chain,and rose diagram,were obtained by recording and loading and used to analyze the intrinsic relationship between mesoscopic parameter variations and macroscopic mechanical response during CPB development.It is of considerable significance to establish the physical model of CPB using the PFC to reveal the mesoscopic structure of CPB.展开更多
CaCl_(2)·6H_(2)O/expanded vermiculite shape stabilized phase change materials(CEV)was prepared by atmospheric impregnation method.Using gold mine tailings as aggregate of cemented paste backfill(CPB)material,the ...CaCl_(2)·6H_(2)O/expanded vermiculite shape stabilized phase change materials(CEV)was prepared by atmospheric impregnation method.Using gold mine tailings as aggregate of cemented paste backfill(CPB)material,the CPB with CEV added was prepared,and the specific heat capacity,thermal conductivity,and uniaxial compressive strength(UCS)of CPB with different cement-tailing ratios and CEV addition ratios were tested,the influence of the above variables on the thermal and mechanical properties of CPB was analyzed.The results show that the maximum encapsulation capacity of expanded vermiculite for CaCl_(2)·6H_(2)O is about 60%,and the melting and solidification enthalpies of CEV can reach 98.87 J/g and 97.56 J/g,respectively.For the CPB without CEV,the specific heat capacity,thermal conductivity,and UCS decrease with the decrease of cement-tailing ratio.For the CPB with CEV added,with the increase of CEV addition ratio,the specific heat capacity increases significantly,and the sensible heat storage capacity and latent heat storage capacity can be increased by at least 10.74%and 218.97%respectively after adding 12%CEV.However,the addition of CEV leads to the increase of pores,and the thermal conductivity and UCS both decrease with the increase of CEV addition.When cement-tailing ratio is 1:8 and 6%,9%,and 12%of CEV are added,the 28-days UCS of CPB is less than 1 MPa.Considering the heat storage capacity and cost price of backfill,the recommended proportion scheme of CPB material presents cement-tailing ratio of 1:6 and 12%CEV,and the most recommended heat storage/release temperature cycle range of CPB with added CEV is from 20 to 40℃.This work can provide theoretical basis for the utilization of heat storage backfill in green mines.展开更多
The shear behavior of backfill-rock composites is crucial for mine safety and the management of surface subsidence.For exposing the shear failure mechanism of backfill-rock composites,we conducted shear tests on backf...The shear behavior of backfill-rock composites is crucial for mine safety and the management of surface subsidence.For exposing the shear failure mechanism of backfill-rock composites,we conducted shear tests on backfill-rock composites under three constant normal loads,compared with the unfilled rock.To investigate the macro-and meso-failure characteristics of the samples in the shear tests,the cracking behavior of samples was recorded by a high-speed camera and acoustic emission monitoring.In parallel with the experimental test,the numerical models of backfill-rock composites and unfilled rock were established using the discrete element method to analyze the continuous-discontinuous shearing process.Based on the damage mechanics and statistics,a novel shear constitutive model was proposed to describe mechanical behavior.The results show that backfill-rock composites had a special bimodal phenomenon of shearing load-deformation curve,i.e.the first shearing peak corresponded to rock break and the second shearing peak induced by the broken of aeolian sand-cement/fly ash paste backfill.Moreover,the shearing characteristic curves of the backfill-rock composites could be roughly divided into four stages,i.e.the shear failure of the specimens experienced:stage I:stress concentration;stage II:crack propagation;stage III:crack coalescence;stage IV:shearing friction.The numerical simulation shows that the existence of aeolian sand-cement/fly ash paste backfill inevitably altered the coalescence type and failure mode of the specimens and had a strengthening effect on the shear strength of backfillrock composites.Based on damage mechanics and statistics,a shear constitutive model was proposed to describe the shear fracture characteristics of specimens,especially the bimodal phenomenon.Finally,the micro-and meso-mechanisms of shear failure were discussed by combining the micro-test and numerical results.The research can advance the better understanding of the shear behavior of backfill-rock composites and contribute to the safety of mining engineering.展开更多
The effects of aerosol-radiation interactions(ARI)are not only important for regional and global climate,but they can also drive particulate matter(PM)pollution.In this study,the ARI contribution to the near-surface f...The effects of aerosol-radiation interactions(ARI)are not only important for regional and global climate,but they can also drive particulate matter(PM)pollution.In this study,the ARI contribution to the near-surface fine PM(PM_(2.5))concentrations in the Guanzhong Basin(GZB)is evaluated under four unfavorable synoptic patterns,including“northlow”,“transition”,“southeast-trough”,and“inland-high”,based on WRF-Chem model simulations of a persistent heavy PM pollution episode in January 2019.Simulations show that ARI consistently decreases both solar radiation reaching down to the surface(SWDOWN)and surface temperature(TSFC),which then reduces wind speed,induces sinking motion,and influences cloud formation in the GZB.However,large differences under the four synoptic patterns still exist.The average reductions of SWDOWN and daytime TSFC in the GZB range from 15.2%and 1.04°C in the case of the“transition”pattern to 26.7%and 1.69°C in the case of the“north-low”pattern,respectively.Furthermore,ARI suppresses the development of the planetary boundary layer(PBL),with the decrease of PBL height(PBLH)varying from 18.7%in the case of the“transition”pattern to 32.0%in the case of the“north-low”pattern.The increase of daytime near-surface PM_(2.5)in the GZB due to ARI is 12.0%,8.1%,9.5%,and 9.7%under the four synoptic patterns,respectively.Ensemble analyses also reveal that when near-surface PM_(2.5)concentrations are low,ARI tends to lower PM_(2.5)concentrations with decreased PBLH,which is caused by enhanced divergence or a transition from divergence to convergence in an area.ARI contributes 15%-25%toward the near-surface PM_(2.5)concentrations during the severe PM pollution period under the four synoptic patterns.展开更多
Experiments on the thermal decomposition of CuSe were carried out by using a thermogravimetric analyzer(TGA)at different heating rates.The kinetic parameters and mechanisms were discussed based on model-free and model...Experiments on the thermal decomposition of CuSe were carried out by using a thermogravimetric analyzer(TGA)at different heating rates.The kinetic parameters and mechanisms were discussed based on model-free and model-based analyses.The decomposition rate and decomposition behavior of CuSe were investigated by using a vacuum thermogravimetric furnace.The results showed that the R3 model was identified as the most probable mechanism function under the present experimental conditions.The average values of activation energy and the pre-exponential factor were 12.344 J/mol and 0.152 s^(−1),respectively.The actual decomposition rate of CuSe was found to be 0.0030 g/(cm^(2)·min).展开更多
Layered backfill is commonly used in mining operations,and its mechanical behavior is strongly influenced by delamination parameters.In this study,13 specimens with different numbers of delamination and delamination a...Layered backfill is commonly used in mining operations,and its mechanical behavior is strongly influenced by delamination parameters.In this study,13 specimens with different numbers of delamination and delamination angle were prepared to investigate the anisotropic mechanical behavior,energy dissipation characteristics and crack development of backfill.P-wave velocity,uniaxial compression,scanning electron microscope(SEM),and acoustic emission(AE)experiments were conducted.The results indicate that:(1)The P-wave velocity has linear and elliptical relationships with the number of delamination surface and delamination angle,respectively;the strength,delamination parameters and P-wave velocity show a high degree of coincidence in terms of their function relationship,which can realize the rapid prediction of strength.(2)The microstructure of the delaminated surface is looser than that of the matrix,leading to a decrease in strength and an increase at the pore-fissure compaction stage.The number and angle of delamination increase linearly with the anisotropy coefficient.(3)The energy evolution in angle-cut backfill can be divided into four stages,with a decrease in the proportion of elastic energy at the initiation stress and peak stress with increasing number of delamination planes and delamination angle.(4)Crack development increases with the number of delamination surface and delamination angle,resulting in a decrease in energy dissipation coefficient and peak AE energy.These findings provide valuable insights for the design of filling materials and processes in mining operations.展开更多
基金the funding support from the National Natural Science Foundation of China(Grant Nos.52304101 and 52004206)the China Postdoctoral Science Foundation(Grant No.2023MD734215)。
文摘Backfill is often employed in mining operations for ground support,with its positive impact on ground stability acknowledged in many underground mines.However,existing studies have predominantly focused only on the stress development within the backfill material,leaving the influence of stope backfilling on stress distribution in surrounding rock mass and ground stability largely unexplored.Therefore,this paper presents numerical models in FLAC3D to investigate,for the first time,the time-dependent stress redistribution around a vertical backfilled stope and its implications on ground stability,considering the creep of surrounding rock mass.Using the Soft Soil constitutive model,the compressibility of backfill under large pressure was captured.It is found that the creep deformation of rock mass exercises compression on backfill and results in a less void ratio and increased modulus for fill material.The compacted backfill conversely influenced the stress distribution and ground stability of rock mass which was a combined effect of wall creep and compressibility of backfill.With the increase of time or/and creep deformation,the minimum principal stress in the rocks surrounding the backfilled stope increased towards the pre-mining stress state,while the deviatoric stress reduces leading to an increased factor of safety and improved ground stability.This improvement effect of backfill on ground stability increased with the increase of mine depth and stope height,while it is also more pronounced for the narrow stope,the backfill with a smaller compression index,and the soft rocks with a smaller viscosity coefficient.Furthermore,the results emphasize the importance of minimizing empty time and backfilling extracted stope as soon as possible for ground control.Reduction of filling gap height enhances the local stability around the roof of stope.
基金supported by the National Natural Science Foundation of China(22278347)the Excellent Doctoral Student Research Innovation Project of Xinjiang University of China(XJU2022BS048)the Postgraduate Innovation Project of Xinjiang Uygur Autonomous Region of China(XJ2023G027).
文摘Low-cost Fe-based disordered rock salt(DRX)Li_(2)FeTiO_(4)is capable of providing high capacity(295 mA h g^(-1))by redox activity of cations(Fe^(2+)/Fe^(4+)and Ti^(3+)/Ti^(4+))and anionic oxygen.However,DRX structures lack transport channels for ions and electrons,resulting in sluggish kinetics,poor electrochemical activity,and cyclability.Herein,graphene conductive carbon network permeated Li_(2)FeTiO_(4)(LFT/C/G)nanofibers are successfully prepared by a facile sol-gel assisted electrospinning method.Ultrafine Li_(2)FeTiO_(4)nanoparticles(2 nm)and one-dimensional(1D)structure provide abu ndant active sites and unobstructed diffu sion channels,accelerating ion diffusion.In addition,introducing graphene reduces the band gap and Li^(+)diffusion barrier and improves the dynamic properties of Li_(2)FeTiO_(4),thus achieving a relatively mild interfacial reaction and reversible redox reaction.As expected,the LFT/C/1.0G cathode delivers a remarkable discharge capacity(238.5 mA h g^(-1)),high energy density(508.8 Wh kg^(-1)),and excellent rate capability(51.2 mA hg^(-1)at 1.0 A g^(-1)).Besides,the LFT/C/1.0G anode also displays a high capacity(514.5 mA h g^(-1)at 500 mA g^(-1))and a remarkable rate capability(243.9 mA h g^(-1)at 8 A g^(-1)).Moreover,the full batteries based on the LFT/C/1.0G symmetric electrode demonstrate a reversible capacity of 117.0 mA h g^(-1)after 100 cycles at 50 mA g^(-1).This study presents useful insights into developing cost-effective DRX cathodes with durable and fast lithium storage.
基金financially supported by the National Key R&D program(no.2022YFB3707501)GDAS’Project of Sci-ence and Technology(no.2021GDASYL-20210102002)+1 种基金Guangdong Provincial Project(nos.2022A0505050053,2021B1515120071,and 2020B1515130007)National Natural Science Foundation of China(no.52130102).
文摘The low damage resistance and fracture toughness hinder the widespread application of ultrahighstrength dual phase(DP)steels.In this work,we propose a novel strategy to improve the fracture toughness of ultrahigh-strength DP steels by an order of magnitude without sacrificing the tensile strength.Six ultrahigh-strength DP steels with varying microstructure but comparable tensile strength(>1400 MPa)were prepared via tailoring the heat treatment process after cold rolling.Additionally,finite element(FE)method incorporated with Gurson-Tvergaad-Needleman(GTN)model and cohesive zone model(CZM)is established to simulate the fracture behavior of DP steel.Twelve model DP steels with different ferrite sizes and F/M strength differences are constructed.The combined experiment and simulation results demonstrate that(i)ferrite/martensite(F/M)interface decohesion prevails in all steels,(ii)the ferrite morphology has a strong influence on the fracture toughness of ultrahigh-strength DP steels,(iii)the effects of matrix type,ferrite size,and F/M hardness difference on the fracture toughness are relatively weak,(iv)the exceptional high fracture toughness of plate-like DP steel can be attributed to the crack deflection,crack divider and crack arrester mechanisms induced by F/M interface decohesion.
基金supported by the National Key R&D Program of China(No.2022YFF0802501)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2022416)+1 种基金the Natural Science Basic Research Program of Shaanxi(No.2022JQ-267)the State Key Laboratory of Loess and Quaternary Geology(No.SKLLQG2335).
文摘The Northeast Plain in China ranks among the top five regions that have been significantly impacted by haze pollution.To effectively control pollution,it is crucial to accurately assess the effects of emission reduction measures.In this study,we analyzed surveillance data and found substantial decreases(ranging from 19.0%to 50.1%)in average annual mass concentrations of key pollutants(such as CO,SO_(2),NO_(2),and PM_(2.5))in the Northeast Plain from 2016 to 2020.To precisely determine the contributions of meteorological conditions and emission reductions to the improvement of air quality in the Northeast Plain,we conducted three scenario simulations.By comparing source emissions in December 2016 and 2020 using the WRF-Chem model(except for SO_(2)),we observed significant reductions of 21.3%,8.8%,and 9.8%in mass concentrations of PM_(2.5),NO_(2),and CO,respectively,from 2016 to 2020.This highlights the essential role that meteorological conditions play in determining air quality in the Northeast Plain.Moreover,further reducing source emissions by 30%in December 2016 resulted in subsequent reductions of 25.3%,29.0%,4.5%,and 30.3%in mass concentrations of PM_(2.5),SO_(2),NO_(2),and CO,respectively,under the same meteorological conditions.Notably,source emission reduction was effective for PM_(2.5),SO_(2),and CO,but not for NO_(2).The improvement in air quality in the Northeast Plain from 2016 to 2020 can be attributed to the combined effects of improved meteorological conditions and reduced pollution sources.
基金supported by the National Natural Science Foundation of China(22278347)。
文摘The adsorption-catalysis ability of metal-based catalysts toward lithium polysulfides(LiPSs)is dominated by the position of their d-/p-band center.An available strategy to strengthen the d-p band center proximity of metal-based catalysts is to fabricate a crystalline-amorphous heterointerface,which markedly enhances LiPS conversion.The polyanionic pyrophosphate of TiP_(2)O_(7)serves as an efficient catalyst and ionic conductor for lithium-sulfur(Li-S)batteries.However,TiP_(2)O_(7)does not fully optimize sulfur redox reactivity due to limitations in factors such as the adsorption-catalysis of sulfur species,Li^(+)diffusion,and electron transfer.Herein,we engineer the crystalline-amorphous heterointerface of TiP_(2)O_(7)combined with carbon nanotubes(CNTs)to facilitate electronic donation from C to TiP_(2)O_(7).This interaction results in an upward shift of the Ti d,enhancing the proximity of the d-p band center in TiP_(2)O_(7)/CNTs.By utilizing TiP_(2)O_(7)/CNTs as both electrode and separator modifier,we optimize the LiPS conversion process,showing a comprehensive strategy to mitigate the diffusion of LiPSs and achieve the bidirectional redox reactions in Li-S batteries.Accordingly,the cell assembled by TiP_(2)O_(7)/CNTs delivers a satisfactory capacity of835 mAh g^(-1)after 300 cycles at 4 C and an impressive initial areal capacity of 3.52 mAh cm^(-2)under the sulfur areal loading of 5 mg cm^(-2)at 0.1 C.Additionally,the Li//Li cells utilizing TiP_(2)O_(7)/CNTs present a prolonged cycling life of up to 1800 h without voltage fluctuation and Li dendrite growth.
基金supported by the National Natural Science Foundation of China(No.22278347)the Excellent Doctoral Student Research Innovation Project of Xinjiang University of China(No.XJU2022BS048)the Postgraduate Innovation Project of Xinjiang Uygur Autonomous Region of China(No.XJ2023G027)。
文摘Symmetric secondary batteries are expected to become promising storage devices on account of their low cost,environmentally friendly and high safety.Nevertheless,the further development of symmetric batteries needs to rely on bipolar electrodes with superior performance.Cation-disordered rocksalt(DRX)Li_(2)FeTiO_(4)shows promising properties as symmetric electrodes,based on the ability of iron to undergo multiple electrochemical reactions over a wide voltage window.Unfortunately,this cation-disordered structure would not provide a cross-path for the rapid migration of Li^(+),ultimately resulting in inferior electrochemical dynamics and cycle stability.Herein,Li_(2)FeTiO_(4)nanoparticles assembled by ultrafine nanocrystals are synthesized via a sol-gel method through an orderly reaction regulation strategy of precursor reactants.Such ultrafine nanocrystals increase the active sites to promote the reversibility of multi-cationic(e.g.,stable Fe^(2+)/Fe^(3+),Ti^(3+)/Ti^(4+)and moderated Fe^(3+)/Fe^(4+))and anionic redox,and maintain the DRX structure well during the cycling process.The half cells with nano-sized Li_(2)FeTiO_(4)as the cathode/anode exhibit a high reversible capacity of 127.8/500.8 mAh/g,respectively.Besides,the Li_(2)FeTiO_(4)//Li_(2)FeTiO_(4)symmetric full cell could provide a reversible capacity of 95.4 mAh/g at 0.1 A/g after 200 cycles.This hierarchical self-assembly by nanocrystal strategy could offer effective guidance for high-performance electrode design for rechargeable secondary batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.U22A20145,52072151,52171211,and 52271218)Jinan Independent Innovative Team(No.2020GXRC015)+3 种基金the Major Program of Shandong Province Natural Science Foundation(No.ZR2023ZD43)Natural Science Foumdation of Jiangsu Province(No.BK20241973)High-level Training Talents of'333'Project in Jiangsu Provincethe Science and Technology Program of University of Jinan(No.XKY2119)
文摘Si,as the most promising anode with high theoretical capacity for next-generation lithium-ion batteries(LIBs),is hampered in commercial application by its poor electrical conductivity and significant volume expansion.Herein,the core-shell Si@SiO_(x)/C@C-Ar(SSC-A)or Si@SiO_(x)/C@C-H_(2)/Ar(SSC-H)composites are purposefully designed by in situ introduction of inorganic SiO_(x)in pure Ar or H_(2)/Ar atmosphere to realize a Si-based anode for LIBs.By introducing different atmospheres,the valence states of SiO_(x)are regulated.The inorganic transition layer formed by the combination of SiO_(x)with higher average valence and asphalt-derived carbon demonstrates better performance in both stabilizing the core-shell structure and inhibiting the agglomeration of Si particles.Given these advantages,the SSC-A electrode exhibits excellent electrochemical performance(1163 mAh g^(-1)after 400 cycles at 1 A g^(-1)),and the commercial blended graphite-SSC-A electrode reaches a specific capacity of 442 mAh g^(-1)with 74.8%capacity retention under the same conditions.Even the SSC-A electrode without Super P maintains an ultrahigh discharge specific capacity of 803 mAh g^(-1)with 60.6%after cycling.Importantly,the full batteries based on SSC-A without Super P achieve a discharge specific capacity of 126 mAh g^(-1)with 28.2%capacity decay after 200 cycles,demonstrating the superior commercial application potential.
基金National Key Research and Development Program of China(No.2022YFC2904900)the National Natural Science Foundation of China(No.U1902221).
文摘The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures(573,583,and 593 K),but the limiting step is controlled by boundary layer diffusion at high temperatures(603 and 613 K).The Se-and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens,with Kirkendall voids generating in the product layer accelerating PbTe particle erosion.After the PbTe impurities in the selenium melt evolve into PbSe and Te,Te is evenly distributed in the selenium melt owing to the solubility of Se and Te.This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.
文摘The authors regret that in the paper of Xin et al.(2024),a bug was found in the used numerical implementation.It concerns one of the damage coefficient that was incorrectly updated during the calculation process.As a consequence for some fluctuation scales,the bug had a limited impact on the found constitutive model.Therefore,the conclusions given in the paper are still valid.The authors have re-analyzed all the constitutive model results presented in the paper and the corrected Table 9,Eqs.(19)and(20),and Fig.18 in the original paper are shown as follows.
基金financially supported by the National Natural Science Foundation of China(Nos. 42007202,41773117)the National Key R&D Plan, Ministry of Science and Technology of China(Mechanism and chemical process characterization of atmospheric particulate matter multi-isotope fractionation)(No. 2017YFC0212703)+1 种基金the Shanghai Science and Technology Innovation Action Plan(No.20dz1204011)the program of Institute of Eco-Chongming and ECNU Happiness Flower。
文摘To investigate the impact of emission controls on ammonia(NH_(3)) pollution in urban atmosphere, observation on NH_(3)(1 hr interval) was performed in Shanghai before, during and after the 2019 China International Import Expo (CIIE) event, along with measurements on inorganic ions, organic tracers and stable nitrogen isotope compositions of ammonium in PM_(2.5). NH_(3)during the CIIE period was 6.5±1.0μg/m^(3), which is 41% and 32% lower than that before and after the event, respectively. Such a decrease was largely ascribed to the emission controls in nonagricultural sources, of which contribution for measured NH_(3)in control phase abated by ~20% compared to that during uncontrol period. Molecular compositions of PAHs and hopanes further suggested a dominant role of the reduced vehicle emissions in the urban NH_(3)abatement during the CIIE period. Our results revealed that vehicle exhaust emission control is an effective way to mitigate NH_(3)pollution and improve air quality in Chinese urban areas.
基金financially supported by the National Natural Science Foundation of China (No. 41773117, 42007202)the National Key R&D Plan, Ministry of Science and Technology of China (Mechanism and chemical process characterization of atmospheric particulate matter multi-isotope fractionation) (No. 2017YFC0212703)+1 种基金the Shanghai Science and Technology Innovation Action Plan (No. 20dz1204011)the program of Institute of Eco-Chongming and ECNU Happiness Flower
文摘To understand the characteristics of atmospheric brown carbon(BrC),daily PM2.5 samples in Xingtai,a small city in North China Plain(NCP),during the four seasons of 2018-2019,were collected and analyzed for optical properties and chemical compositions.The light absorption at 365 nm(abs λ=365 nm)displayed a strong seasonal variation with the highest value in winter(29.0±14.3 M/m),which was 3.2∼5.4-fold of that in other seasons.A strong correlation of abs λ=365 nm with benzo(b)fluoranthene(BbF)was only observed in winter,indicating that coal combustion was the major source for BrC in the season due to the enhanced domestic heating.The mass absorbing efficiency of BrC also exhibited a similar seasonal pattern,and was found to correlate linearly with the aerosol pH,suggesting a positive effect of aerosol acidity on the optical properties and formation of BrC in the city.Positive matrix factorization(PMF)analysis further showed that on a yearly basis the major source for BrC was biomass burning,which accounted for 34% of the total BrC,followed by secondary formation(26.7%),coal combustion(21.3%)and fugitive dust(18%).However,the contribution from coal combustionwas remarkably enhanced in winter,accounting for∼40%of the total.Our work revealed that more efforts of“shifting coal to clean energy”are necessary in rural areas and small cities in NCP in order to further mitigate PM2.5 pollution in China.
基金supported by the National Natural Science Foundation of China (No.41205115)
文摘To investigate the composition and possible sources of particles, especially during heavy haze pollution, a single particle aerosol mass spectrometer（SPAMS） was deployed to measure the changes of single particle species and sizes during October of 2014, in Beijing. A total of 2,871,431 particles with both positive and negative spectra were collected and characterized in combination with the adaptive resonance theory neural network algorithm（ART-2a）. Eight types of particles were classified： dust particles（dust, 8.1%）, elemental carbon（EC, 29.0%）, organic carbon（OC, 18.0%）, EC and OC combined particles（ECOC, 9.5%）,Na-K containing particles（Na K, 7.9%）, K-containing particles（K, 21.8%）, organic nitrogen and potassium containing particles（KCN, 2.3%）, and metal-containing particles（metal,3.6%）. Three haze pollution events（P1, P2, P3） and one clean period（clean） were analyzed,based on the mass and number concentration of PM_（2.5）and the back trajectory results from the hybrid single particle Lagrangian integrated trajectory model（Hysplit-4 model）. Results showed that EC, OC and K were the major components of single particles during the three haze pollution periods, which showed clearly increased ratios compared with those in the clean period. Results from the mixing state of secondary species of different types of particles showed that sulfate and nitrate were more readily mixed with carbon-containing particles during haze pollution episodes than in clean periods.
基金financially supported by the National Natural Science Foundation of China(Nos.51874229,52074212,51674188,51504182,51404191,and 51405381)the Natural Science Basic Research Plan of Shaanxi Province of China(Nos.2015JQ5187,2018JQ5183,and 2018JM5161)+3 种基金the Scientific Research Program funded by the Shaanxi Education Department(No.15JK1466)the China Postdoctoral Science Foundation(No.2015M582685)the Outstanding Youth Science Fund of Xi’an University of Science and Technology(No.2018YQ2-01)supported by the National Research Council of Science&and Technology(NST)grant by the Korea Korean government(MSIP)(No.CRC-16-38502-KICT)。
文摘Several special mechanical properties,such as dilatancy and compressibility,of cemented paste backfill(CPB)are controlled by its internal microstructure and evolution.The mesoscopic structure changes of CPB during the development process were investigated.On the basis of the scanning electron microscopy(SEM)and mechanical test results of CPB,the particle size information of CPB was extracted,and a two-dimensional particle flow code(PFC)model of CPB was established to analyze the evolution rule of mesoscopic parameters during CPB development.The embedded FISH language in PFC was used to develop a program for establishing a PFC model on the basis of the SEM results.The mesoscopic parameters of CPB samples at different curing times,such as coordination number(C_(n)),contact force chain,and rose diagram,were obtained by recording and loading and used to analyze the intrinsic relationship between mesoscopic parameter variations and macroscopic mechanical response during CPB development.It is of considerable significance to establish the physical model of CPB using the PFC to reveal the mesoscopic structure of CPB.
基金supported by the National Natural Science Foundation of China(Nos.51974225,51874229,51674188,51904224,51904225)the Shaanxi Innovative Talents Cultivate Program-New-star Plan of Science and Technology,China(No.2018KJXX-083)+2 种基金the Natural Science Basic Research Plan of Shaanxi Province of China(Nos.2018JM 5161,2018JQ5183,2019JM-074)the Scientific Research Program funded by the Shaanxi Provincial Education Department,China(No.19JK0543)the Outstanding Youth Science Fund of Xi’an University of Science and Technology,China(No.2018YQ2-01)。
文摘CaCl_(2)·6H_(2)O/expanded vermiculite shape stabilized phase change materials(CEV)was prepared by atmospheric impregnation method.Using gold mine tailings as aggregate of cemented paste backfill(CPB)material,the CPB with CEV added was prepared,and the specific heat capacity,thermal conductivity,and uniaxial compressive strength(UCS)of CPB with different cement-tailing ratios and CEV addition ratios were tested,the influence of the above variables on the thermal and mechanical properties of CPB was analyzed.The results show that the maximum encapsulation capacity of expanded vermiculite for CaCl_(2)·6H_(2)O is about 60%,and the melting and solidification enthalpies of CEV can reach 98.87 J/g and 97.56 J/g,respectively.For the CPB without CEV,the specific heat capacity,thermal conductivity,and UCS decrease with the decrease of cement-tailing ratio.For the CPB with CEV added,with the increase of CEV addition ratio,the specific heat capacity increases significantly,and the sensible heat storage capacity and latent heat storage capacity can be increased by at least 10.74%and 218.97%respectively after adding 12%CEV.However,the addition of CEV leads to the increase of pores,and the thermal conductivity and UCS both decrease with the increase of CEV addition.When cement-tailing ratio is 1:8 and 6%,9%,and 12%of CEV are added,the 28-days UCS of CPB is less than 1 MPa.Considering the heat storage capacity and cost price of backfill,the recommended proportion scheme of CPB material presents cement-tailing ratio of 1:6 and 12%CEV,and the most recommended heat storage/release temperature cycle range of CPB with added CEV is from 20 to 40℃.This work can provide theoretical basis for the utilization of heat storage backfill in green mines.
文摘The shear behavior of backfill-rock composites is crucial for mine safety and the management of surface subsidence.For exposing the shear failure mechanism of backfill-rock composites,we conducted shear tests on backfill-rock composites under three constant normal loads,compared with the unfilled rock.To investigate the macro-and meso-failure characteristics of the samples in the shear tests,the cracking behavior of samples was recorded by a high-speed camera and acoustic emission monitoring.In parallel with the experimental test,the numerical models of backfill-rock composites and unfilled rock were established using the discrete element method to analyze the continuous-discontinuous shearing process.Based on the damage mechanics and statistics,a novel shear constitutive model was proposed to describe mechanical behavior.The results show that backfill-rock composites had a special bimodal phenomenon of shearing load-deformation curve,i.e.the first shearing peak corresponded to rock break and the second shearing peak induced by the broken of aeolian sand-cement/fly ash paste backfill.Moreover,the shearing characteristic curves of the backfill-rock composites could be roughly divided into four stages,i.e.the shear failure of the specimens experienced:stage I:stress concentration;stage II:crack propagation;stage III:crack coalescence;stage IV:shearing friction.The numerical simulation shows that the existence of aeolian sand-cement/fly ash paste backfill inevitably altered the coalescence type and failure mode of the specimens and had a strengthening effect on the shear strength of backfillrock composites.Based on damage mechanics and statistics,a shear constitutive model was proposed to describe the shear fracture characteristics of specimens,especially the bimodal phenomenon.Finally,the micro-and meso-mechanisms of shear failure were discussed by combining the micro-test and numerical results.The research can advance the better understanding of the shear behavior of backfill-rock composites and contribute to the safety of mining engineering.
基金This work is financially supported by the National Key R&D Plan(Grant No.2017YFC0210000)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB40030200)+1 种基金the National Natural Science Foundation of China(Grant No.41975175)the Fundamental Research Funds for the Central Universities of China。
文摘The effects of aerosol-radiation interactions(ARI)are not only important for regional and global climate,but they can also drive particulate matter(PM)pollution.In this study,the ARI contribution to the near-surface fine PM(PM_(2.5))concentrations in the Guanzhong Basin(GZB)is evaluated under four unfavorable synoptic patterns,including“northlow”,“transition”,“southeast-trough”,and“inland-high”,based on WRF-Chem model simulations of a persistent heavy PM pollution episode in January 2019.Simulations show that ARI consistently decreases both solar radiation reaching down to the surface(SWDOWN)and surface temperature(TSFC),which then reduces wind speed,induces sinking motion,and influences cloud formation in the GZB.However,large differences under the four synoptic patterns still exist.The average reductions of SWDOWN and daytime TSFC in the GZB range from 15.2%and 1.04°C in the case of the“transition”pattern to 26.7%and 1.69°C in the case of the“north-low”pattern,respectively.Furthermore,ARI suppresses the development of the planetary boundary layer(PBL),with the decrease of PBL height(PBLH)varying from 18.7%in the case of the“transition”pattern to 32.0%in the case of the“north-low”pattern.The increase of daytime near-surface PM_(2.5)in the GZB due to ARI is 12.0%,8.1%,9.5%,and 9.7%under the four synoptic patterns,respectively.Ensemble analyses also reveal that when near-surface PM_(2.5)concentrations are low,ARI tends to lower PM_(2.5)concentrations with decreased PBLH,which is caused by enhanced divergence or a transition from divergence to convergence in an area.ARI contributes 15%-25%toward the near-surface PM_(2.5)concentrations during the severe PM pollution period under the four synoptic patterns.
基金supported by the Basic Research Plan of Yunnan Province,China(No.2019FA020)the Yunling Scholars of Yunnan Province,China(No.KKRC201952012)the Leading Talents of Industrial Technology in Ten Thousand Talents Plan of Yunnan Province,China,and the Scientist Studio of Yunnan Province,China.
文摘Experiments on the thermal decomposition of CuSe were carried out by using a thermogravimetric analyzer(TGA)at different heating rates.The kinetic parameters and mechanisms were discussed based on model-free and model-based analyses.The decomposition rate and decomposition behavior of CuSe were investigated by using a vacuum thermogravimetric furnace.The results showed that the R3 model was identified as the most probable mechanism function under the present experimental conditions.The average values of activation energy and the pre-exponential factor were 12.344 J/mol and 0.152 s^(−1),respectively.The actual decomposition rate of CuSe was found to be 0.0030 g/(cm^(2)·min).
文摘Layered backfill is commonly used in mining operations,and its mechanical behavior is strongly influenced by delamination parameters.In this study,13 specimens with different numbers of delamination and delamination angle were prepared to investigate the anisotropic mechanical behavior,energy dissipation characteristics and crack development of backfill.P-wave velocity,uniaxial compression,scanning electron microscope(SEM),and acoustic emission(AE)experiments were conducted.The results indicate that:(1)The P-wave velocity has linear and elliptical relationships with the number of delamination surface and delamination angle,respectively;the strength,delamination parameters and P-wave velocity show a high degree of coincidence in terms of their function relationship,which can realize the rapid prediction of strength.(2)The microstructure of the delaminated surface is looser than that of the matrix,leading to a decrease in strength and an increase at the pore-fissure compaction stage.The number and angle of delamination increase linearly with the anisotropy coefficient.(3)The energy evolution in angle-cut backfill can be divided into four stages,with a decrease in the proportion of elastic energy at the initiation stress and peak stress with increasing number of delamination planes and delamination angle.(4)Crack development increases with the number of delamination surface and delamination angle,resulting in a decrease in energy dissipation coefficient and peak AE energy.These findings provide valuable insights for the design of filling materials and processes in mining operations.
