Gradient microstructures strengthened by serrated Grain Boundaries(GBs)were achieved through a combination of Gradient Strain Deformation(GSD)and Serration Heat Treatment(SHT),with particular focus on microstructural ...Gradient microstructures strengthened by serrated Grain Boundaries(GBs)were achieved through a combination of Gradient Strain Deformation(GSD)and Serration Heat Treatment(SHT),with particular focus on microstructural evolution,underlying mechanisms,and the critical influencing factors.Dynamic recrystallization governed the microstructural evolution in the fine-grained and transition regions during GSD,where multiple nucleation mechanisms were active.Plastic deformation facilitated the dissolution ofγ'phase in fine-grained regions,ultimately resulting in its morphological transformation.During the subsequent SHT,serrated GBs formed within the gradient microstructures produced by prior GSD without disrupting the grain size gradient,thereby enhancing creep resistance.Two distinct mechanisms associated withγ'gbparticles governed the formation of the serrations at GBs.Owing to the stronger dragging effect of grain boundary junctions in fine-grained regions,the amplitude and wavelength of serrations in these regions were smaller than those in coarse-grained regions.Moreover,the formation of serrations exhibited a strong dependence on the inherent properties of the GBs.The random high-angle grain boundaries(HAGBs)with misorientation angles in the range of 30-59°tended to become serrated more easily during SHT due to their high mobility and the accelerated precipitation ofγ'gbparticles at them.Low-ΣHAGBs and low-angle GBs were not prone to form serrations.In particular,serration formation was completely inhibited atΣ3 twin boundaries due to their extremely low mobility and the absence ofγ'gbparticles.展开更多
Traditional oilfields face increasing extraction challenges, primarily due to reservoir quality degradation and production decline, which are further exacerbated by volatile international crude oil prices—illustrated...Traditional oilfields face increasing extraction challenges, primarily due to reservoir quality degradation and production decline, which are further exacerbated by volatile international crude oil prices—illustrated by Brent Crude’s trajectory from pandemic-induced negative pricing to geopolitically driven surges exceeding USD 100 per barrel. This study addresses these complexities through an integrated methodological framework applied to medium-permeability sandstone reservoirs in the Xinjiang oilfield by combining advanced numerical simulations with multivariate regression analysis. The methodology employs Latin Hypercube Sampling (LHS) to stratify geological parameter distributions and constructs heterogeneous reservoir models using Petrel software, rigorously validated through historical production data matching. Production forecasting integrates numerical simulation and Decline Curve Analysis (DCA), while investment estimation utilizes Ordinary Least Squares (OLS) regression to correlate engineering parameters with drilling and completion costs. Economic evaluation incorporates Discounted Cash Flow (DCF) modeling and breakeven analysis, establishing techno-economic boundaries via oil price sensitivity analysis ranging from USD 40 to 90 per barrel. Visualization tools, including 3D heatmaps, delineate nonlinear interactions among engineering, geological, and investment datasets under economic constraints. Key findings demonstrate that for the target reservoirs, as oil prices increase from USD 40 to USD 90 per barrel, the minimum economic thickness threshold decreases from approximately 5.7 m to about 2.5 m, with model prediction errors consistently below 25% across validation datasets. This framework provides scientifically grounded decision support for optimizing capital allocation and offers actionable insights to enhance undeveloped hydrocarbon development planning amid market uncertainty. Ultimately, it supports national energy security through technically robust and economically viable resource exploitation strategies.展开更多
To elucidate the deformation mechanisms ofγ-TiAl,the nanoindentation experiments and crystal plasticity finite element(CPFE)simulation were employed to investigate the effects of crystal orientations and GBs on the m...To elucidate the deformation mechanisms ofγ-TiAl,the nanoindentation experiments and crystal plasticity finite element(CPFE)simulation were employed to investigate the effects of crystal orientations and GBs on the mechanical properties ofγ-TiAl alloys.A crystal plasticity constitutive model was developed,and load-displacement curves,hardness,and Young's modulus were obtained for both single grains and GBs inγ-TiAl alloys.Based on the aforementioned model,this study investigated the distribution patterns of surface morphology around the indentation sites of individual grain and GBs.It also analyzed the cumulative shear strain distribution,slip system activation,and the interaction between GBs and dislocation slip for various crystal orientations.The results indicate that the mechanical response and pileup behavior exhibit significant anisotropy due to the interplay among the indenter geometry,material slip systems,and cumulative shear strain distribution.Moreover,the interaction between GBs and dislocation slip substantially alters dislocation distribution,thereby influencing material flow and playing a critical role in the mechanical response and plastic deformation of the material.展开更多
High-performance lead-free piezoelectric single crystals are urgently needed for next-generation actuators and transducers.In this study,we reveal that a compositionally driven tetragonal-pseudocubic(T-PC)phase bounda...High-performance lead-free piezoelectric single crystals are urgently needed for next-generation actuators and transducers.In this study,we reveal that a compositionally driven tetragonal-pseudocubic(T-PC)phase boundary,in conjunction with an octahedral order-disorder tilting transition,significantly enhances the piezoelectric response in Nb^(5+)-substitution(Bi_(0.48)Na_(0.425)K_(0.055)Ba_(0.04))(Ti_(0.98)Nb_(0.02))O_(3)(BNKBT-2Nb)single crystals.The crystal achieves an outstanding piezoelectric coefficient of d33=662 pC/N at room temperature.In situ X-ray diffraction confirms an electric field-induced transition from the PC to T phase.Atomic-resolution HADDF-STEM analysis reveals an increase in the c/a ratio(c/a>1.01)on the local scale and ordered octahe-dral tilting of the a^(0)a^(0)c+type driven by the poling field.The single crystals exhibit excellent piezoelectric per-formance over a broad temperature range,achieving a peak d_(33) of 920 pC/N at approximately 92℃.Furthermore,the polar states exhibit a pronounced frequency dependence near the depolarization temperature.These findings provide critical insight into the structure-property relationship and offer a promising pathway for designing advanced lead-free piezoelectric crystals for functional electromechanical applications.展开更多
A large-scale view of the magnetospheric cusp is expected to be obtained by the Soft X-ray Imager(SXI)onboard the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE).However,it is challenging to trace the three-d...A large-scale view of the magnetospheric cusp is expected to be obtained by the Soft X-ray Imager(SXI)onboard the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE).However,it is challenging to trace the three-dimensional cusp boundary from a two-dimensional X-ray image because the detected X-ray signals will be integrated along the line of sight.In this work,a global magnetohydrodynamic code was used to simulate the X-ray images and photon count images,assuming an interplanetary magnetic field with a pure Bz component.The assumption of an elliptic cusp boundary at a given altitude was used to trace the equatorward and poleward boundaries of the cusp from a simulated X-ray image.The average discrepancy was less than 0.1 RE.To reduce the influence of instrument effects and cosmic X-ray backgrounds,image denoising was considered before applying the method above to SXI photon count images.The cusp boundaries were reasonably reconstructed from the noisy X-ray image.展开更多
Enhancing the strength of nanotwinned aluminum(Al)is essential for the development of nextgeneration high-end chip technology.To better understand the detwinning behavior of nanotwinned Al under conditions with no res...Enhancing the strength of nanotwinned aluminum(Al)is essential for the development of nextgeneration high-end chip technology.To better understand the detwinning behavior of nanotwinned Al under conditions with no resolved shear stress acting on the twin boundaries,we conducted molecular dynamics simulations of uniaxial tensile deformation in nanotwinned single-crystal Al at room temperature.Detwinning is observed only when the twin boundary spacing is 7.01 A.At larger spacings,twin boundaries remain parallel to the loading direction,with no rotation or bending,indicating negligible migration.Detwinning is triggered by localized stress from dislocation interactions,with detwinning fraction evolving synchronously with dislocation density.In the absence of detwinning,dislocations inclined toward twin boundaries interact frequently with them,leading to a loss of coherency that intensifies with increasing twin boundary spacing.These findings enhance understanding of the plastic deformation mechanisms in nanotwinned metals at very small twin boundary spacings,supplement the conventional understanding of twin boundary stability,and therefore suggest potential pathways for designing Al-based nanostructures with enhanced stability or controllable plastic deformation.展开更多
Ferrite-carbon composites effectively absorb electromagnetic(EM)waves via coupled mechanisms.However,the dynamic evolution of intrinsic polarization and magnetic loss mechanisms following interfacial coupling has long...Ferrite-carbon composites effectively absorb electromagnetic(EM)waves via coupled mechanisms.However,the dynamic evolution of intrinsic polarization and magnetic loss mechanisms following interfacial coupling has long been overlooked,impeding broadening of the ultra-broadband EM wave absorption performance in heterostructures.Herein,via surface ligand modulation,in situ growth of 0D Fe_(3)O_(4)quantum dots(QDs)on the surface of 1D carbon nanotubes triggers grain boundary coupling.The energy rebalancing effect at the interface induces an extreme charge rearrangement within the Fe_(3)O_(4)QDs.This rearrangement enhances dipole orientation hysteresis and charge accumulation,resulting in charge and interfacial polarization losses.Meanwhile,for subcritical Fe_(3)O_(4)QDs,short-range magnetic resonance and magnetic exchange-triggered magnetic resonance transfer synergistically enhance the magnetic loss.Through charge rearrangement/magnetic resonance induced by0D/1D grain boundary coupling,an effective bandwidth of nearly 10 GHz is achieved at a minimal thickness of 2 mm,covering the X and Ku bands.This strategy provides an effective paradigm and novel theoretical insights for ultra-broadband electromagnetic wave absorption applications.展开更多
On February 8,2025,a remote area in the Caribbean Sea was rocked by a large M_(W)7.6(USGS,2025) earthquake,centered 209 km SSW of Georgetown,the capital of the Cayman Islands,and the largest city(population~41 000) of...On February 8,2025,a remote area in the Caribbean Sea was rocked by a large M_(W)7.6(USGS,2025) earthquake,centered 209 km SSW of Georgetown,the capital of the Cayman Islands,and the largest city(population~41 000) of the British Overseas Territories(Figure 1).The earthquake was significant due to its large magnitude,potential regional impact,and the possibility of generating a tsunami.展开更多
Solute atoms and precipitates significantly influence the mechanical properties of Mg alloys.Previous studies have mainly focused on the segregation behaviors of Mg alloys after annealing.In this study,we investigated...Solute atoms and precipitates significantly influence the mechanical properties of Mg alloys.Previous studies have mainly focused on the segregation behaviors of Mg alloys after annealing.In this study,we investigated the segregation behaviors of an Mg-RE alloy under deformation.We found that the enrichment of solute atoms occurred in{101^(-)1}compressive twin boundaries under compression at 298 K without any annealing in an Mg-RE alloy by scanning transmission electron microscopy and energy-dispersive X-ray analysis.The segregated solutes and precipitates impeded the twin growth,partially contributing to the formation of small-sized{101^(-)1}compressive twins.This research indicates the twin boundaries can be strengthened by segregated solutes and precipitates formed under deformation at room temperature.展开更多
Detecting internal defects,particularly voids behind linings,is critical for ensuring the structural integrity of aging high-speed rail(HSR)tunnel networks.While ground-penetrating radar(GPR)is widely employed,systema...Detecting internal defects,particularly voids behind linings,is critical for ensuring the structural integrity of aging high-speed rail(HSR)tunnel networks.While ground-penetrating radar(GPR)is widely employed,systematic quantification of performance boundaries for air-coupled(A-CGPR)and ground-coupled(G-CGPR)systems within the complex electromagnetic environment of multilayer reinforced HSR tunnels remains limited.This study establishes physics-based quantitative performance limits for A-CGPR and G-CGPR through rigorously validated GPRMax finite-difference time-domain(FDTD)simulations and comprehensive field validation over a 300 m operational HSR tunnel section.Key performance metrics were quantified as functions of:(a)detection distance(A-CGPR:2.0–4.5 m;G-CGPR:≤0.1 m),(b)antenna frequency(A-CGPR:300 MHz;G-CGPR:400/900 MHz),(c)reinforcement configuration(unreinforced,single-layer,multilayer rebar),and(d)void geometry(axial length:0.1–1.0 m;radial depth:0.1–0.5 m).Key findings demonstrate:a.A-CGPR(300 MHz):Reliably detects axial voids≥0.3 m at distances≤3 m in minimally reinforced(single-layer rebar)linings(field R2=0.89).Performance degrades significantly at distances>3 m(>60%signal attenuation at 4.5 m)or under multilayer rebar interference,causing 25%–40%accuracy loss for voids<0.3 m.Optimal distance:2.0–2.5 m.b.G-CGPR(900 MHz):Achieves<5%size measurement error for axial voids≥0.1 m and radial voids≥0.2 m in unreinforced linings.Resolution degrades under multilayer reinforcement due to severe signal attenuation,increasing axial void detection error to 10%–20%for voids≥0.3 m and constraining radial size measurement.c.Synergistic Framework:A hybrid inspection protocol is proposed,integrating A-CGPR(20 km/h)for rapid large-area screening and targeted G-CGPR(3 km/h)for high-resolution verification of identified anomalies.This framework enhances NDT efficiency while reducing estimated lifecycle inspection costs by 34%compared to G-CGPR alone.This research provides the first physics-derived quantitative detection thresholds for A-CGPR and G-CGPR in multi-rebar HSR tunnels,validated through field-correlated simulations.Future work will focus on multi-frequency antenna arrays and deep learning algorithms to mitigate reinforcement interference.The established performance boundaries and hybrid framework offer critical guidance for optimizing tunnel lining inspection strategies in extensive HSR networks.展开更多
The present work reports on microscopic analyses of recombination at grain boundaries(GBs)in polycrystalline Li-doped(Ag,Cu)_(2)ZnSn(S,Se)_(4)(LiACZTSSe)and Cu_(2)ZnSnS_(4)(CZTS)absorber layers in high-efficiency sola...The present work reports on microscopic analyses of recombination at grain boundaries(GBs)in polycrystalline Li-doped(Ag,Cu)_(2)ZnSn(S,Se)_(4)(LiACZTSSe)and Cu_(2)ZnSnS_(4)(CZTS)absorber layers in high-efficiency solar cells(conversion efficiencies of 14.4%and 10.8%).Recombination velocities sG B were determined at a large number of GBs by evaluating profiles extracted from cathodoluminescence intensity distributions across GBs in these polycrystalline layers.In both Li-ACZTSSe and CZTS absorber layers,the sG B values exhibited wide ranges over several orders of magnitude with a median values of 680 and 1100 cm s^(-1)for the Li-ACZTSSe and CZTS absorbers.展开更多
Shape control of nickel sulfide(NiS_(2))catalysts is beneficial for boosting their catalytic performances,which is vital to their practical application as a class of advanced non-noble electro-catalysts.However,precis...Shape control of nickel sulfide(NiS_(2))catalysts is beneficial for boosting their catalytic performances,which is vital to their practical application as a class of advanced non-noble electro-catalysts.However,precisely controlling the formation kinetics and fabricate ultrathin NiS_(2)nanostructures still remains challenge.Herein,we provide an injection rate-mediated method to fabricate ultrathin NiS_(2)nanocages(HNCs)with hierarchical walls,high-density lattice defects and abundant grain boundaries(GBs).Through mechanism analysis,we find the injection rate determines the concentration of S_(2)−in the steady state and thus control the growth pattern,leading to the formation of NiS_(2)HNCs at slow etching kinetics and NiCo PBA@NiS_(2)frames at fast etching kinetics,respectively.Benefiting from the ultrathin and hierarchical walls that minimize the mass transport restrictions,the high-density lattice defects and GBs that offer abundant unsaturated reaction sites,the NiS_(2)HNCs exhibit obviously enhanced electrocatalytic activity and stability toward OER,with overpotential of 255mV to reach 10mA/cm^(2)and a Tafel slope of 27.44mV/dec,surpassing the performances of NiCo PBA@NiS_(2)frames and commercial RuO_(2).展开更多
The control of solute segregation at grain boundaries is of significance in engineering alloy properties.However,there is currently a lack of a physics-informed predictive model for estimating solute segre-gation ener...The control of solute segregation at grain boundaries is of significance in engineering alloy properties.However,there is currently a lack of a physics-informed predictive model for estimating solute segre-gation energies.Here we propose novel electronic descriptors for grain-boundary segregation based on the valence,electronegativity and size of solutes.By integrating the non-local coordination number of surfaces,we build a predictive analytic framework for evaluating the segregation energies across various solutes,grain-boundary structures,and segregation sites.This framework uncovers not only the coupling rule of solutes and matrices,but also the origin of solute-segregation determinants,which stems from the d-and sp-states hybridization in alloying.Our scheme establishes a novel picture for grain-boundary segregation and provides a useful tool for the design of advanced alloys.展开更多
Copper(Cu)-based catalysts show significant potential for producing high value-added C_(2+)products in electrocatalytic CO_(2)/CO reduction reactions(CO(2)RR).However,the structural reconfiguration during operation po...Copper(Cu)-based catalysts show significant potential for producing high value-added C_(2+)products in electrocatalytic CO_(2)/CO reduction reactions(CO(2)RR).However,the structural reconfiguration during operation poses substantial challenges in identifying the intrinsic catalytic active site,especially under similar mass transport conditions.Herein,three typical and commercial Cu-based catalysts(Cu,CuO,and Cu_(2)O)are chosen as representatives to elucidate the structure-activity relationship of CORR in the membrane electrode assembly electrolyzer.Notably,only the Cu catalyst demonstrates the most suppression of hydrogen evolution reaction,thus achieving the highest FE of 86.7% for C_(2+)products at a current density of 500 mA cm^(-2) and maintaining a stable electrolysis over 110 h at a current of 200 mA cm^(-2).The influence of chemical valence state of Cu,electrochemical surface area,and local pH were firstly investigated and ruled out for the significant FE differences.Finally,based on the structure analysis from high resolution transmission electron microscope,OH-adsorption,in situ infrared spectroscopy and density functional theory calculations,it is suggested that the asymmetric C-C coupling(via ^(*)CHO and ^(*)CO)is the most probable reaction pathway for forming C_(2+)products,with Cu(100)-dominant grain boundaries(GBs)being the most favorable active sites.These findings provide deeper insights into the synergistic relationship between crystal facets and GBs in electrocatalytic systems.展开更多
Austenitic stainless steels(ASSs)are widely used in various in-dustries such as aerospace,nuclear energy,food,and biotechnol-ogy owing to their exceptional combination of corrosion resistance,weldability,toughness,and...Austenitic stainless steels(ASSs)are widely used in various in-dustries such as aerospace,nuclear energy,food,and biotechnol-ogy owing to their exceptional combination of corrosion resistance,weldability,toughness,and formability[1,2].However,a signifi-cant drawback of ASSs is their low yield strength,which limits their applications in extreme environments[3].Grain boundary(GB)engineering plays a crucial role in enhancing the strength of ASSs[4,5].For instance,grain refinement techniques such as cold rolling followed by annealing[6],severe plastic deformation(SPD)[7],and surface mechanical attrition/rolling treatments[8,9]introduce high-angle GBs(HAGBs)into ASSs,thereby improving their strength.However,the high density of HAGBs limits their ca-pacity for dislocation storage and multiplication,leading to a sig-nificant loss of ductility[10,11].Additionally,several studies have shown that twin boundaries(TBs)can simultaneously enhance the strength,toughness,and corrosion resistance of ASSs[12,13].展开更多
Teaching is widely recognised as an emotionally demanding profession,particularly during the early stages of learning to teach.While research on pre-service teachers’emotions often foregrounds the detrimental effects...Teaching is widely recognised as an emotionally demanding profession,particularly during the early stages of learning to teach.While research on pre-service teachers’emotions often foregrounds the detrimental effects of negative emotions,less is known about how such emotions contribute to professional learning.This study uses qualitative thematic analysis to explore how 10 pre-service English teachers experience and interpret negative emotions during practicum and how these experiences shape professional boundary negotiation.Drawing on interviews and emotion diaries collected across a seven-week practicum,the findings show that frustration,helplessness,and loss of control surfaced when participants encountered limits of responsibility,authority,and role expectations.Rather than indicating incompetence,these experiences prompted reflection on what teaching can reasonably demand and supported more realistic,sustainable understandings of teaching.展开更多
At present,artificial intelligence(AI)technologies are deeply integrated into all scenarios of teaching,research,and student development in higher education.Intelligent teaching systems,research data processing tools,...At present,artificial intelligence(AI)technologies are deeply integrated into all scenarios of teaching,research,and student development in higher education.Intelligent teaching systems,research data processing tools,and AI platforms for student management are gradually becoming important aids to educational activities.This transformation disrupts the traditional framework of university teachers’responsibilities:fundamental tasks in knowledge transmission are diverted,repetitive work in research is replaced,and some managerial functions in student development are covered.Consequently,the boundaries of teachers’responsibilities are increasingly blurred,and the substitution effect has led to role anxiety and confusion about professional positioning.Clarifying the specific impact of AI on teachers’responsibilities,identifying the replaceable and irreplaceable domains,and exploring effective paths for fulfilling responsibilities are key to resolving teachers’role-identity crisis,promoting the implementation of“human-AI collaborative”education models,and ensuring the high-quality digital development of higher education.展开更多
Low-angle grain boundaries(LAGBs)are one of the solidification defects in single-crystal nickel-based superalloys and are detrimental to the mechanical properties.The formation of LAGBs is related to dendrite deformat...Low-angle grain boundaries(LAGBs)are one of the solidification defects in single-crystal nickel-based superalloys and are detrimental to the mechanical properties.The formation of LAGBs is related to dendrite deformation,while the mechanism has not been fully understood at the mesoscale.In this work,a model coupling dendrite growth,thermal-solutal-fluid flow,thermal stress and flow-induced dendrite deformation via cellular automaton-finite volume method and finite element method is developed to study the formation of LAGBs in single crystal superalloys.Results reveal that the bending of dendrites is primarily attributed to the thermal-solutal convection-induced dendrite deformation.The mechanical stress of dendrite deformation develops and stabilises as solidification proceeds.As the width of the mushy zone gets stable,stresses are built up and then dendritic elastoplastic bending occurs at some thin primary dendrites with the wider inter-dendritic space.There are three characteristic zones of stress distribution along the solidification direction:(i)no stress concentration in the fully solidified regions;(ii)stress developing in the primary dendrite bridging region,and(iii)stress decrease in the inter-dendritic uncontacted zone.The stresses reach maximum near the initial dendrite bridging position.The lower temperature gradients,the finer primary dendritic trunks and sudden reductions in local dendritic trunk radius jointly promote the elastoplastic deformation of the dendrites.Corresponding measures are suggested to reduce LAGBs.展开更多
Asymmetric tilt boundaries on conventional twin boundaries(TBs)are significant for understanding the role of twins on coordinating plastic deformation in many metallic alloys.However,the formation modes of many asymme...Asymmetric tilt boundaries on conventional twin boundaries(TBs)are significant for understanding the role of twins on coordinating plastic deformation in many metallic alloys.However,the formation modes of many asymmetric tilt boundaries are hard to be accounted for based on traditional theoretical models,and the corresponding solute segregation is complex.Herein,atomic structures of a specific asymmetric boundary on{1012}TBs were reveled using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM),molecular dynamics(MD)and density functional theory(DFT)simulations.Reaction between<a60>M dislocations and the{1012}TB can generate a~61°/25°asymmetric tilt boundary.The segregation of Gd and Zn atoms is closely related to the aggregateddislocations and the interfacial interstices of the asymmetric tilt boundary,which is energetically favorable in reducing the total system energy.展开更多
Due to the heterogeneity of rock masses and the variability of in situ stress,the traditional linear inversion method is insufficiently accurate to achieve high accuracy of the in situ stress field.To address this cha...Due to the heterogeneity of rock masses and the variability of in situ stress,the traditional linear inversion method is insufficiently accurate to achieve high accuracy of the in situ stress field.To address this challenge,nonlinear stress boundaries for a numerical model are determined through regression analysis of a series of nonlinear coefficient matrices,which are derived from the bubbling method.Considering the randomness and flexibility of the bubbling method,a parametric study is conducted to determine recommended ranges for these parameters,including the standard deviation(σb)of bubble radii,the non-uniform coefficient matrix number(λ)for nonlinear stress boundaries,and the number(m)and positions of in situ stress measurement points.A model case study provides a reference for the selection of these parameters.Additionally,when the nonlinear in situ stress inversion method is employed,stress distortion inevitably occurs near model boundaries,aligning with the Saint Venant's principle.Two strategies are proposed accordingly:employing a systematic reduction of nonlinear coefficients to achieve high inversion accuracy while minimizing significant stress distortion,and excluding regions with severe stress distortion near the model edges while utilizing the central part of the model for subsequent simulations.These two strategies have been successfully implemented in the nonlinear in situ stress inversion of the Xincheng Gold Mine and have achieved higher inversion accuracy than the linear method.Specifically,the linear and nonlinear inversion methods yield root mean square errors(RMSE)of 4.15 and 3.2,and inversion relative errors(δAve)of 22.08%and 17.55%,respectively.Therefore,the nonlinear inversion method outperforms the traditional multiple linear regression method,even in the presence of a systematic reduction in the nonlinear stress boundaries.展开更多
基金co-supported by the National Natural Science Foundation of China(Nos.52305421 and 52175363)the General Research Fund of Hong Kong,China(No.15223520)the projects from the Hong Kong Polytechnic University,China(Nos.4-W418,1-ZE1W,4-WZ4W and 1-CD4H)。
文摘Gradient microstructures strengthened by serrated Grain Boundaries(GBs)were achieved through a combination of Gradient Strain Deformation(GSD)and Serration Heat Treatment(SHT),with particular focus on microstructural evolution,underlying mechanisms,and the critical influencing factors.Dynamic recrystallization governed the microstructural evolution in the fine-grained and transition regions during GSD,where multiple nucleation mechanisms were active.Plastic deformation facilitated the dissolution ofγ'phase in fine-grained regions,ultimately resulting in its morphological transformation.During the subsequent SHT,serrated GBs formed within the gradient microstructures produced by prior GSD without disrupting the grain size gradient,thereby enhancing creep resistance.Two distinct mechanisms associated withγ'gbparticles governed the formation of the serrations at GBs.Owing to the stronger dragging effect of grain boundary junctions in fine-grained regions,the amplitude and wavelength of serrations in these regions were smaller than those in coarse-grained regions.Moreover,the formation of serrations exhibited a strong dependence on the inherent properties of the GBs.The random high-angle grain boundaries(HAGBs)with misorientation angles in the range of 30-59°tended to become serrated more easily during SHT due to their high mobility and the accelerated precipitation ofγ'gbparticles at them.Low-ΣHAGBs and low-angle GBs were not prone to form serrations.In particular,serration formation was completely inhibited atΣ3 twin boundaries due to their extremely low mobility and the absence ofγ'gbparticles.
文摘Traditional oilfields face increasing extraction challenges, primarily due to reservoir quality degradation and production decline, which are further exacerbated by volatile international crude oil prices—illustrated by Brent Crude’s trajectory from pandemic-induced negative pricing to geopolitically driven surges exceeding USD 100 per barrel. This study addresses these complexities through an integrated methodological framework applied to medium-permeability sandstone reservoirs in the Xinjiang oilfield by combining advanced numerical simulations with multivariate regression analysis. The methodology employs Latin Hypercube Sampling (LHS) to stratify geological parameter distributions and constructs heterogeneous reservoir models using Petrel software, rigorously validated through historical production data matching. Production forecasting integrates numerical simulation and Decline Curve Analysis (DCA), while investment estimation utilizes Ordinary Least Squares (OLS) regression to correlate engineering parameters with drilling and completion costs. Economic evaluation incorporates Discounted Cash Flow (DCF) modeling and breakeven analysis, establishing techno-economic boundaries via oil price sensitivity analysis ranging from USD 40 to 90 per barrel. Visualization tools, including 3D heatmaps, delineate nonlinear interactions among engineering, geological, and investment datasets under economic constraints. Key findings demonstrate that for the target reservoirs, as oil prices increase from USD 40 to USD 90 per barrel, the minimum economic thickness threshold decreases from approximately 5.7 m to about 2.5 m, with model prediction errors consistently below 25% across validation datasets. This framework provides scientifically grounded decision support for optimizing capital allocation and offers actionable insights to enhance undeveloped hydrocarbon development planning amid market uncertainty. Ultimately, it supports national energy security through technically robust and economically viable resource exploitation strategies.
基金National Natural Science Foundation of China(52065036,52365018)Natural Science Foundation of Gansu(23JRRA760,24JRRA175,25JRRA060)+1 种基金Hongliu Outstanding Youth Foundation of Lanzhou University of TechnologyLeading Innovative Talents Project of Changzhou(CQ20210111)。
文摘To elucidate the deformation mechanisms ofγ-TiAl,the nanoindentation experiments and crystal plasticity finite element(CPFE)simulation were employed to investigate the effects of crystal orientations and GBs on the mechanical properties ofγ-TiAl alloys.A crystal plasticity constitutive model was developed,and load-displacement curves,hardness,and Young's modulus were obtained for both single grains and GBs inγ-TiAl alloys.Based on the aforementioned model,this study investigated the distribution patterns of surface morphology around the indentation sites of individual grain and GBs.It also analyzed the cumulative shear strain distribution,slip system activation,and the interaction between GBs and dislocation slip for various crystal orientations.The results indicate that the mechanical response and pileup behavior exhibit significant anisotropy due to the interplay among the indenter geometry,material slip systems,and cumulative shear strain distribution.Moreover,the interaction between GBs and dislocation slip substantially alters dislocation distribution,thereby influencing material flow and playing a critical role in the mechanical response and plastic deformation of the material.
基金supported by the National Natural Science Foundation of China(Grant No.11704301)the Natural Science Basic Research Plan in Shaanxi Province of China(Program No.2022JM212)supported by the Ministry of Science and Higher Education of the Russian Federation(FSEG-2023-0016).
文摘High-performance lead-free piezoelectric single crystals are urgently needed for next-generation actuators and transducers.In this study,we reveal that a compositionally driven tetragonal-pseudocubic(T-PC)phase boundary,in conjunction with an octahedral order-disorder tilting transition,significantly enhances the piezoelectric response in Nb^(5+)-substitution(Bi_(0.48)Na_(0.425)K_(0.055)Ba_(0.04))(Ti_(0.98)Nb_(0.02))O_(3)(BNKBT-2Nb)single crystals.The crystal achieves an outstanding piezoelectric coefficient of d33=662 pC/N at room temperature.In situ X-ray diffraction confirms an electric field-induced transition from the PC to T phase.Atomic-resolution HADDF-STEM analysis reveals an increase in the c/a ratio(c/a>1.01)on the local scale and ordered octahe-dral tilting of the a^(0)a^(0)c+type driven by the poling field.The single crystals exhibit excellent piezoelectric per-formance over a broad temperature range,achieving a peak d_(33) of 920 pC/N at approximately 92℃.Furthermore,the polar states exhibit a pronounced frequency dependence near the depolarization temperature.These findings provide critical insight into the structure-property relationship and offer a promising pathway for designing advanced lead-free piezoelectric crystals for functional electromechanical applications.
基金funded by the National Natural Science Foundation of China(NNSFC)under Grant Numbers 42322408,42188101,and 42441809Additional support was provided by the Climbing Program of the National Space Science Center(NSSC,Grant No.E4PD3005)as well as the Specialized Research Fund for State Key Laboratories of China.
文摘A large-scale view of the magnetospheric cusp is expected to be obtained by the Soft X-ray Imager(SXI)onboard the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE).However,it is challenging to trace the three-dimensional cusp boundary from a two-dimensional X-ray image because the detected X-ray signals will be integrated along the line of sight.In this work,a global magnetohydrodynamic code was used to simulate the X-ray images and photon count images,assuming an interplanetary magnetic field with a pure Bz component.The assumption of an elliptic cusp boundary at a given altitude was used to trace the equatorward and poleward boundaries of the cusp from a simulated X-ray image.The average discrepancy was less than 0.1 RE.To reduce the influence of instrument effects and cosmic X-ray backgrounds,image denoising was considered before applying the method above to SXI photon count images.The cusp boundaries were reasonably reconstructed from the noisy X-ray image.
基金founded by the National Natural Science Foundation of China under grant numbers 52375325,52105410Anhui Provincial Natural Science Foundation under grant number 2308085ME164.
文摘Enhancing the strength of nanotwinned aluminum(Al)is essential for the development of nextgeneration high-end chip technology.To better understand the detwinning behavior of nanotwinned Al under conditions with no resolved shear stress acting on the twin boundaries,we conducted molecular dynamics simulations of uniaxial tensile deformation in nanotwinned single-crystal Al at room temperature.Detwinning is observed only when the twin boundary spacing is 7.01 A.At larger spacings,twin boundaries remain parallel to the loading direction,with no rotation or bending,indicating negligible migration.Detwinning is triggered by localized stress from dislocation interactions,with detwinning fraction evolving synchronously with dislocation density.In the absence of detwinning,dislocations inclined toward twin boundaries interact frequently with them,leading to a loss of coherency that intensifies with increasing twin boundary spacing.These findings enhance understanding of the plastic deformation mechanisms in nanotwinned metals at very small twin boundary spacings,supplement the conventional understanding of twin boundary stability,and therefore suggest potential pathways for designing Al-based nanostructures with enhanced stability or controllable plastic deformation.
基金supported by The Youth Innovation Team of Shaanxi Universities and The Innovation and Entrepreneurship Team of Special Support Program for‘Sanqin’Talentthe Special Support Program for High-level Talents of Shaanxi Province(No.2020-44)the China Postdoctoral Science Foundation(2022M723884)。
文摘Ferrite-carbon composites effectively absorb electromagnetic(EM)waves via coupled mechanisms.However,the dynamic evolution of intrinsic polarization and magnetic loss mechanisms following interfacial coupling has long been overlooked,impeding broadening of the ultra-broadband EM wave absorption performance in heterostructures.Herein,via surface ligand modulation,in situ growth of 0D Fe_(3)O_(4)quantum dots(QDs)on the surface of 1D carbon nanotubes triggers grain boundary coupling.The energy rebalancing effect at the interface induces an extreme charge rearrangement within the Fe_(3)O_(4)QDs.This rearrangement enhances dipole orientation hysteresis and charge accumulation,resulting in charge and interfacial polarization losses.Meanwhile,for subcritical Fe_(3)O_(4)QDs,short-range magnetic resonance and magnetic exchange-triggered magnetic resonance transfer synergistically enhance the magnetic loss.Through charge rearrangement/magnetic resonance induced by0D/1D grain boundary coupling,an effective bandwidth of nearly 10 GHz is achieved at a minimal thickness of 2 mm,covering the X and Ku bands.This strategy provides an effective paradigm and novel theoretical insights for ultra-broadband electromagnetic wave absorption applications.
文摘On February 8,2025,a remote area in the Caribbean Sea was rocked by a large M_(W)7.6(USGS,2025) earthquake,centered 209 km SSW of Georgetown,the capital of the Cayman Islands,and the largest city(population~41 000) of the British Overseas Territories(Figure 1).The earthquake was significant due to its large magnitude,potential regional impact,and the possibility of generating a tsunami.
基金support from Interdisciplinary Research Project for Young Teachers of USTB Fundamental Research Funds for the Central Universities(Grant no.FRF-IDRY-23-030).
文摘Solute atoms and precipitates significantly influence the mechanical properties of Mg alloys.Previous studies have mainly focused on the segregation behaviors of Mg alloys after annealing.In this study,we investigated the segregation behaviors of an Mg-RE alloy under deformation.We found that the enrichment of solute atoms occurred in{101^(-)1}compressive twin boundaries under compression at 298 K without any annealing in an Mg-RE alloy by scanning transmission electron microscopy and energy-dispersive X-ray analysis.The segregated solutes and precipitates impeded the twin growth,partially contributing to the formation of small-sized{101^(-)1}compressive twins.This research indicates the twin boundaries can be strengthened by segregated solutes and precipitates formed under deformation at room temperature.
基金funded by the Key Project of Science&Technology Research ofChina Academy of Railway Sciences,grant number 2023YJ022.
文摘Detecting internal defects,particularly voids behind linings,is critical for ensuring the structural integrity of aging high-speed rail(HSR)tunnel networks.While ground-penetrating radar(GPR)is widely employed,systematic quantification of performance boundaries for air-coupled(A-CGPR)and ground-coupled(G-CGPR)systems within the complex electromagnetic environment of multilayer reinforced HSR tunnels remains limited.This study establishes physics-based quantitative performance limits for A-CGPR and G-CGPR through rigorously validated GPRMax finite-difference time-domain(FDTD)simulations and comprehensive field validation over a 300 m operational HSR tunnel section.Key performance metrics were quantified as functions of:(a)detection distance(A-CGPR:2.0–4.5 m;G-CGPR:≤0.1 m),(b)antenna frequency(A-CGPR:300 MHz;G-CGPR:400/900 MHz),(c)reinforcement configuration(unreinforced,single-layer,multilayer rebar),and(d)void geometry(axial length:0.1–1.0 m;radial depth:0.1–0.5 m).Key findings demonstrate:a.A-CGPR(300 MHz):Reliably detects axial voids≥0.3 m at distances≤3 m in minimally reinforced(single-layer rebar)linings(field R2=0.89).Performance degrades significantly at distances>3 m(>60%signal attenuation at 4.5 m)or under multilayer rebar interference,causing 25%–40%accuracy loss for voids<0.3 m.Optimal distance:2.0–2.5 m.b.G-CGPR(900 MHz):Achieves<5%size measurement error for axial voids≥0.1 m and radial voids≥0.2 m in unreinforced linings.Resolution degrades under multilayer reinforcement due to severe signal attenuation,increasing axial void detection error to 10%–20%for voids≥0.3 m and constraining radial size measurement.c.Synergistic Framework:A hybrid inspection protocol is proposed,integrating A-CGPR(20 km/h)for rapid large-area screening and targeted G-CGPR(3 km/h)for high-resolution verification of identified anomalies.This framework enhances NDT efficiency while reducing estimated lifecycle inspection costs by 34%compared to G-CGPR alone.This research provides the first physics-derived quantitative detection thresholds for A-CGPR and G-CGPR in multi-rebar HSR tunnels,validated through field-correlated simulations.Future work will focus on multi-frequency antenna arrays and deep learning algorithms to mitigate reinforcement interference.The established performance boundaries and hybrid framework offer critical guidance for optimizing tunnel lining inspection strategies in extensive HSR networks.
基金support by the German-Israeli Helmholtz International Research School HI-SCORE(HIRS-0008)by the project“EFFCISⅡ”funded by the Federal Ministry for Economic Affairs and Climate Action(BMWK)under contract numbers 03EE1059B+9 种基金the Australian Renewable Energy Agency(ARENA)as part of ARENA’s Transformative Research Accelerating Commercialization(TRAC)Programthe Australian Research Council(ARC)Discovery Project(DP230102463)Linkage Project(LP200301593)Baosteel-Australia Joint Research and Development Center(BA19010)support from the Australian Center of Advanced Photovoltaics(ACAP)as a recipient of the ACAP Fel owship(RG172864-B)financial support of the Australian Research Council(ARC)Future Fel owship(FT190100756)funding from the European Union’s H2020 ERC-Consolidator program under grant agreement number no.866018(SENSATE)by the Science and Innovation Ministry of Spain projects number PID2023-148976OB-C41(CURIO-CITY)and PCI2023-145971-2(ACT-FAST,CET-Partnership 2023 program)the European Union’s Horizon research and innovation program under the Marie Skøodowska-Curie grant agreement no.10115148(LEK-PV)part of Maria de Maeztu Units of Excel ence Program CEX2023-001300-M/funded by MICIU/AEI/10.13039/501100011033
文摘The present work reports on microscopic analyses of recombination at grain boundaries(GBs)in polycrystalline Li-doped(Ag,Cu)_(2)ZnSn(S,Se)_(4)(LiACZTSSe)and Cu_(2)ZnSnS_(4)(CZTS)absorber layers in high-efficiency solar cells(conversion efficiencies of 14.4%and 10.8%).Recombination velocities sG B were determined at a large number of GBs by evaluating profiles extracted from cathodoluminescence intensity distributions across GBs in these polycrystalline layers.In both Li-ACZTSSe and CZTS absorber layers,the sG B values exhibited wide ranges over several orders of magnitude with a median values of 680 and 1100 cm s^(-1)for the Li-ACZTSSe and CZTS absorbers.
基金financially supported by National Natural Science Foundation of China (Nos. 21902078, 22279062, 22232004,22072067)the supports from National and Local Joint Engineering Research Center of Biomedical Functional Materialsa project sponsored by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Shape control of nickel sulfide(NiS_(2))catalysts is beneficial for boosting their catalytic performances,which is vital to their practical application as a class of advanced non-noble electro-catalysts.However,precisely controlling the formation kinetics and fabricate ultrathin NiS_(2)nanostructures still remains challenge.Herein,we provide an injection rate-mediated method to fabricate ultrathin NiS_(2)nanocages(HNCs)with hierarchical walls,high-density lattice defects and abundant grain boundaries(GBs).Through mechanism analysis,we find the injection rate determines the concentration of S_(2)−in the steady state and thus control the growth pattern,leading to the formation of NiS_(2)HNCs at slow etching kinetics and NiCo PBA@NiS_(2)frames at fast etching kinetics,respectively.Benefiting from the ultrathin and hierarchical walls that minimize the mass transport restrictions,the high-density lattice defects and GBs that offer abundant unsaturated reaction sites,the NiS_(2)HNCs exhibit obviously enhanced electrocatalytic activity and stability toward OER,with overpotential of 255mV to reach 10mA/cm^(2)and a Tafel slope of 27.44mV/dec,surpassing the performances of NiCo PBA@NiS_(2)frames and commercial RuO_(2).
基金support from the National Natural Science Foundation of China(Nos.22173034,11974128,52130101)the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure(No.SKL202206SIC)+2 种基金the Program of Innovative Research Team(in Science and Technology)in University of Jilin Province,the Program for JLU(Jilin University)Science and Technology Innovative Research Team(No.2017TD-09)the Fundamental Research Funds for the Central Universitiesthe computing resources of the High Performance Computing Center of Jilin University,China.
文摘The control of solute segregation at grain boundaries is of significance in engineering alloy properties.However,there is currently a lack of a physics-informed predictive model for estimating solute segre-gation energies.Here we propose novel electronic descriptors for grain-boundary segregation based on the valence,electronegativity and size of solutes.By integrating the non-local coordination number of surfaces,we build a predictive analytic framework for evaluating the segregation energies across various solutes,grain-boundary structures,and segregation sites.This framework uncovers not only the coupling rule of solutes and matrices,but also the origin of solute-segregation determinants,which stems from the d-and sp-states hybridization in alloying.Our scheme establishes a novel picture for grain-boundary segregation and provides a useful tool for the design of advanced alloys.
文摘Copper(Cu)-based catalysts show significant potential for producing high value-added C_(2+)products in electrocatalytic CO_(2)/CO reduction reactions(CO(2)RR).However,the structural reconfiguration during operation poses substantial challenges in identifying the intrinsic catalytic active site,especially under similar mass transport conditions.Herein,three typical and commercial Cu-based catalysts(Cu,CuO,and Cu_(2)O)are chosen as representatives to elucidate the structure-activity relationship of CORR in the membrane electrode assembly electrolyzer.Notably,only the Cu catalyst demonstrates the most suppression of hydrogen evolution reaction,thus achieving the highest FE of 86.7% for C_(2+)products at a current density of 500 mA cm^(-2) and maintaining a stable electrolysis over 110 h at a current of 200 mA cm^(-2).The influence of chemical valence state of Cu,electrochemical surface area,and local pH were firstly investigated and ruled out for the significant FE differences.Finally,based on the structure analysis from high resolution transmission electron microscope,OH-adsorption,in situ infrared spectroscopy and density functional theory calculations,it is suggested that the asymmetric C-C coupling(via ^(*)CHO and ^(*)CO)is the most probable reaction pathway for forming C_(2+)products,with Cu(100)-dominant grain boundaries(GBs)being the most favorable active sites.These findings provide deeper insights into the synergistic relationship between crystal facets and GBs in electrocatalytic systems.
基金financially supported by the National Key R&D program(No.2022YFB3707501)the GDAS’Project of Science and Technology(No.2022GDASZH-2022010202)the Guangdong Provincial Project(Nos.2022A0505050053,2021B1515120071,and 2020B1515130007)。
文摘Austenitic stainless steels(ASSs)are widely used in various in-dustries such as aerospace,nuclear energy,food,and biotechnol-ogy owing to their exceptional combination of corrosion resistance,weldability,toughness,and formability[1,2].However,a signifi-cant drawback of ASSs is their low yield strength,which limits their applications in extreme environments[3].Grain boundary(GB)engineering plays a crucial role in enhancing the strength of ASSs[4,5].For instance,grain refinement techniques such as cold rolling followed by annealing[6],severe plastic deformation(SPD)[7],and surface mechanical attrition/rolling treatments[8,9]introduce high-angle GBs(HAGBs)into ASSs,thereby improving their strength.However,the high density of HAGBs limits their ca-pacity for dislocation storage and multiplication,leading to a sig-nificant loss of ductility[10,11].Additionally,several studies have shown that twin boundaries(TBs)can simultaneously enhance the strength,toughness,and corrosion resistance of ASSs[12,13].
基金funded by the 2025 Special Research Project for Master of Education,Zhaoqing Institute of Educational Development Studies(ZOJYY2025044)AI+Knowledge Mapping of Advanced English Course(Certified by Academic Affairs Department of Zhaoqing University in 2025,No.3).
文摘Teaching is widely recognised as an emotionally demanding profession,particularly during the early stages of learning to teach.While research on pre-service teachers’emotions often foregrounds the detrimental effects of negative emotions,less is known about how such emotions contribute to professional learning.This study uses qualitative thematic analysis to explore how 10 pre-service English teachers experience and interpret negative emotions during practicum and how these experiences shape professional boundary negotiation.Drawing on interviews and emotion diaries collected across a seven-week practicum,the findings show that frustration,helplessness,and loss of control surfaced when participants encountered limits of responsibility,authority,and role expectations.Rather than indicating incompetence,these experiences prompted reflection on what teaching can reasonably demand and supported more realistic,sustainable understandings of teaching.
文摘At present,artificial intelligence(AI)technologies are deeply integrated into all scenarios of teaching,research,and student development in higher education.Intelligent teaching systems,research data processing tools,and AI platforms for student management are gradually becoming important aids to educational activities.This transformation disrupts the traditional framework of university teachers’responsibilities:fundamental tasks in knowledge transmission are diverted,repetitive work in research is replaced,and some managerial functions in student development are covered.Consequently,the boundaries of teachers’responsibilities are increasingly blurred,and the substitution effect has led to role anxiety and confusion about professional positioning.Clarifying the specific impact of AI on teachers’responsibilities,identifying the replaceable and irreplaceable domains,and exploring effective paths for fulfilling responsibilities are key to resolving teachers’role-identity crisis,promoting the implementation of“human-AI collaborative”education models,and ensuring the high-quality digital development of higher education.
基金sponsored by the National Natural Science Foundation of China(Grant Nos.52074182,52304406 and U23A20612)the Natural Science Foundation of Shanghai(Grant Nos.22ZR1430700 and 23TS1401900)+1 种基金the National Science and Technology Major Project(No.2017-VII-0008-0102)Neng Ren acknowledges the Startup Fund for Young Faculty at SJTU.
文摘Low-angle grain boundaries(LAGBs)are one of the solidification defects in single-crystal nickel-based superalloys and are detrimental to the mechanical properties.The formation of LAGBs is related to dendrite deformation,while the mechanism has not been fully understood at the mesoscale.In this work,a model coupling dendrite growth,thermal-solutal-fluid flow,thermal stress and flow-induced dendrite deformation via cellular automaton-finite volume method and finite element method is developed to study the formation of LAGBs in single crystal superalloys.Results reveal that the bending of dendrites is primarily attributed to the thermal-solutal convection-induced dendrite deformation.The mechanical stress of dendrite deformation develops and stabilises as solidification proceeds.As the width of the mushy zone gets stable,stresses are built up and then dendritic elastoplastic bending occurs at some thin primary dendrites with the wider inter-dendritic space.There are three characteristic zones of stress distribution along the solidification direction:(i)no stress concentration in the fully solidified regions;(ii)stress developing in the primary dendrite bridging region,and(iii)stress decrease in the inter-dendritic uncontacted zone.The stresses reach maximum near the initial dendrite bridging position.The lower temperature gradients,the finer primary dendritic trunks and sudden reductions in local dendritic trunk radius jointly promote the elastoplastic deformation of the dendrites.Corresponding measures are suggested to reduce LAGBs.
基金supported by the Scientific and Technological Developing Scheme of Jilin Province under grants no.YDZJ202301ZYTS538the Chinese Academy of Sciences Youth Innovation Promotion Association under grants number 2023234+3 种基金the National Natural Science Foundation of China under grants number U21A20323the Scientific and Technological Developing Scheme of Jilin Province under grants no.SKL202302038the Major Scientific and Technological Projects of Hebei Province under grants No.23291001Zthe Scientific and Technology Project of Hanjiang District.
文摘Asymmetric tilt boundaries on conventional twin boundaries(TBs)are significant for understanding the role of twins on coordinating plastic deformation in many metallic alloys.However,the formation modes of many asymmetric tilt boundaries are hard to be accounted for based on traditional theoretical models,and the corresponding solute segregation is complex.Herein,atomic structures of a specific asymmetric boundary on{1012}TBs were reveled using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM),molecular dynamics(MD)and density functional theory(DFT)simulations.Reaction between<a60>M dislocations and the{1012}TB can generate a~61°/25°asymmetric tilt boundary.The segregation of Gd and Zn atoms is closely related to the aggregateddislocations and the interfacial interstices of the asymmetric tilt boundary,which is energetically favorable in reducing the total system energy.
基金funded by the National Key R&D Program of China(Grant No.2022YFC2903904)the National Natural Science Foundation of China(Grant Nos.51904057 and U1906208).
文摘Due to the heterogeneity of rock masses and the variability of in situ stress,the traditional linear inversion method is insufficiently accurate to achieve high accuracy of the in situ stress field.To address this challenge,nonlinear stress boundaries for a numerical model are determined through regression analysis of a series of nonlinear coefficient matrices,which are derived from the bubbling method.Considering the randomness and flexibility of the bubbling method,a parametric study is conducted to determine recommended ranges for these parameters,including the standard deviation(σb)of bubble radii,the non-uniform coefficient matrix number(λ)for nonlinear stress boundaries,and the number(m)and positions of in situ stress measurement points.A model case study provides a reference for the selection of these parameters.Additionally,when the nonlinear in situ stress inversion method is employed,stress distortion inevitably occurs near model boundaries,aligning with the Saint Venant's principle.Two strategies are proposed accordingly:employing a systematic reduction of nonlinear coefficients to achieve high inversion accuracy while minimizing significant stress distortion,and excluding regions with severe stress distortion near the model edges while utilizing the central part of the model for subsequent simulations.These two strategies have been successfully implemented in the nonlinear in situ stress inversion of the Xincheng Gold Mine and have achieved higher inversion accuracy than the linear method.Specifically,the linear and nonlinear inversion methods yield root mean square errors(RMSE)of 4.15 and 3.2,and inversion relative errors(δAve)of 22.08%and 17.55%,respectively.Therefore,the nonlinear inversion method outperforms the traditional multiple linear regression method,even in the presence of a systematic reduction in the nonlinear stress boundaries.
