The specific surface area(S S)and pore size(D)exhibit an inherent trade-off in the microscale design of bone implants:larger pores typically correlate with reduced surface area and vice versa.This relationship has att...The specific surface area(S S)and pore size(D)exhibit an inherent trade-off in the microscale design of bone implants:larger pores typically correlate with reduced surface area and vice versa.This relationship has attracted notable attention because of its critical role in the regulation of cell adhesion and osteogenesis.However,it remains largely unclear how S S and D affect the generated bone tissue and dynamically change during long-term osteogenesis.Herein,by applying rigorous geometric mapping to minimal surfaces,we constructed precisely partitioned and layer-by-layer thickened tissue models to simulate osteogenesis across different temporal scales and thereby track the dynamic evolution of geometric characteristics,permeability,and mechanobiological tissue differentiation.The high-S S samples were found to facilitate the rapid formation of new bone tissue in the early stages.However,their smaller pores tended to cause occlusions,hindering further tissue development.In contrast,low-S S samples showed slower bone regeneration,but their larger pores provided adequate physical space for tissue regeneration and mass transport,ultimately promoting bone formation in the long term.Mechanobiological regulation suggests that fibrous tissue formation inhibits additional bone formation,establishing a dynamic equilibrium between osteogenesis and pore space to sustain nutrient/waste exchange throughout the regenerative process.Overall,smaller pores are preferable in implants for minimally loaded osteoplasty procedures focused on early-stage bone consolidation,whereas larger pores are preferable in dynamically loaded implants requiring prolonged mechanical stability.展开更多
A new analytical model for geometric size and forming force prediction in incremental flanging(IF)is presented in this work.The complex deformation characteristics of IF are considered in the modeling process,which ca...A new analytical model for geometric size and forming force prediction in incremental flanging(IF)is presented in this work.The complex deformation characteristics of IF are considered in the modeling process,which can accurately describe the strain and stress states in IF.Based on strain analysis,the model can predict the material thickness distribution and neck height after IF.By considering contact area,strain characteristics,material thickness changes,and friction,the model can predict specific moments and corresponding values of maximum axial forming force and maximum horizontal forming force during IF.In addition,an IF experiment involving different tool diameters,flanging diameters,and opening hole diameters is conducted.On the basis of the experimental strain paths,the strain characteristics of different deformation zones are studied,and the stable strain ratio is quantitatively described through two dimensionless parameters:relative tool diameter and relative hole diameter.Then,the changing of material thickness and forming force in IF,and the variation of minimum material thickness,neck height,maximum axial forming force,and maximum horizontal forming force with flanging parameters are studied,and the reliability of the analytical model is verified in this process.Finally,the influence of the horizontal forming force on the tool design and the fluctuation of the forming force are explained.展开更多
Grain size and formation of the Peripheral Coarse Grain(PCG)defect influence the mechanical and crash properties of extruded profiles.Controlling microstructural evolution during the extrusion of 6XXX series aluminum ...Grain size and formation of the Peripheral Coarse Grain(PCG)defect influence the mechanical and crash properties of extruded profiles.Controlling microstructural evolution during the extrusion of 6XXX series aluminum alloys is therefore essential to ensure the performance of structural components.In this work,three profiles with the same nominal geometry were extruded with a die comprising three different bearing geometries to create different extrusion conditions.Each profile was analyzed experimentally to gather data on the microstructure and mechanical properties.Bulge testing revealed that Profile 2,with the thickest PCG layer(490-1150µm),exhibited worse mechanical performance,with a hoop strain at fracture of 0.08 and a peak load of 51.5 kN,compared to Profiles 1 and 3,which had higher hoop strains(0.13 and 0.14)and peak loads(56.1 and 57.6 kN,respectively).Finite Element Method(FEM)simulations of the extrusion process were carried out using Qform Extrusion UK with a post-processing subroutine developed and implemented to calculate additional parameters such as the stored energy,percentage dynamic recrystallization,grain size,and PCG formation based on standard output parameters from the simulation including strain,temperature and strain rate.The simulation demonstrated that the highest strain rate(40-220 s^(-1))and stored energy(150,000-440,000 J m^(-3))in Profile 2 led to the thickest PCG layer.Based on these results,the proposed predictive model was validated against experimental data,demonstrating high accuracy in predicting PCG thickness and grain size while effectively capturing the influence of process parameters on microstructural evolution.展开更多
The shallow slip deficit(SSD)during strike-slip earthquakes raises a question of how the strain budget is accommodated over multiple cycles.However,the origin of variable SSD observed in different earthquakes is still...The shallow slip deficit(SSD)during strike-slip earthquakes raises a question of how the strain budget is accommodated over multiple cycles.However,the origin of variable SSD observed in different earthquakes is still under debate because each earthquake has its unique initial stress condition.Here,we derive the slip model of the 2021 M W 7.4 Maduo earthquake in Qinghai,China,using multi-track radar images.Our results revealed that,in contrast to the large SSD on segments close to the epicenter,a much smaller SSD was observed at the west terminus of the rupture,where aftershock distribution indicates that the fault changes dip direction at 6 km depth.The 2021 Maduo earthquake thus represents an extraordinary case of significant along-strike SSD variation.After accounting for interseismic,postseismic,and diffuse off-fault deformation,we find that this variation is likely contributed by the along-dipping geometrical variation,implying that a multi-segment earthquake may leave heterogeneous stress condition on the fault with different amounts of SSD.展开更多
The Wilczek–Zee connection(WZC)is a key concept in the study of topology of quantum systems.Here,we introduce the double Wilczek–Zee connection(DWZC)which naturally appears in the pure-state quantum geometric tensor...The Wilczek–Zee connection(WZC)is a key concept in the study of topology of quantum systems.Here,we introduce the double Wilczek–Zee connection(DWZC)which naturally appears in the pure-state quantum geometric tensor(QGT),another important concept in the field of quantum geometry.The DWZC is Hermitian with respect to the two integer indices,just like the original Hermitian WZC.Based on the symmetric logarithmic derivative operator,we propose a mixed-state quantum geometric tensor.Using the symmetric properties of the DWZC,we find that the real part of the QGT is connected to the real part of the DWZC and the square of eigenvalue differences of the density matrix,whereas the imaginary part can be given in terms of the imaginary part of the DWZC and the cube of the eigenvalue differences.For density matrices with full rank or no full rank,the QGT can be given in terms of real and imaginary parts of the DWZC.展开更多
Lattice materials have demonstrated promising potential in engineering applications owing to their exceptional lightweight,high specific strength,and tunable mechanical properties.However,the traditional homogenizatio...Lattice materials have demonstrated promising potential in engineering applications owing to their exceptional lightweight,high specific strength,and tunable mechanical properties.However,the traditional homogenization methods based on the classical elasticity theory struggle to accurately describe the non-classical mechanical behaviors of lattice materials,especially when dealing with complex unit-cell geometries featured by non-symmetric configurations or non-single central node connections.In response to this limitation,this study establishes a generalized homogenization model based on the micropolar theory framework,employing Hill's boundary conditions to precisely predict the equivalent moduli of complex lattice materials.By introducing the independent rotational degree of freedom(DOF)characteristic of the micropolar theory,the proposed model successfully overcomes the limitation of conventional methods in accurately describing the asymmetric deformation and scale effects.We initially calculate the constitutive relations of two-dimensional(2D)cross-shaped multi-node chiral lattices and subsequently extend the method to three-dimensional(3D)lattices,successfully predicting the mechanical properties of both traditional and eccentric body-centered cubic(BCC)lattices.The theoretical model is validated through the finite element numerical verification which shows excellent consistency with the theoretical predictions.A further parametric study investigates the influence of geometric parameters,revealing the underlying size-effect mechanism.This paper provides a reliable theoretical tool for the design and property optimization of complex lattice materials.展开更多
The alpine grassland vegetation on the Qinghai-Tibet Plateau is composed of plant patches in varied sizes.It remains uncertain whether vegetation recovery following grazing exclusion(GE)in degraded grasslands is drive...The alpine grassland vegetation on the Qinghai-Tibet Plateau is composed of plant patches in varied sizes.It remains uncertain whether vegetation recovery following grazing exclusion(GE)in degraded grasslands is driven by increases in patches number(NP),patch size(PS),or both.We based our predictions on two hypotheses:GE intensifies plant competition,and facilitation prevails near patches while competition prevails in interpatch spaces.We predicted that the NP would remain stable or decrease and PS would increase under GE treatment.To evaluate these predictions,we conducted a study in six lightly degraded alpine grasslands under free grazing(FG)conditions in Bangor County,Xizang Autonomous Region,China,with corresponding GE treatments using transects in 2017 and 2018.Results revealed that four sites in 2017 and five sites in 2018 had reduced NP and increased PS,with probabilities of 0.033(2017)and 0.004(2018),respectively,and a joint probability of 0.0001 under the null hypothesis that GE does not affect NP or PS.The NP reduction was solely due to the decrease in small patch sizes.An increase in PS was common across species,and a predominant tendency for NP reduction was observed among species across the sites.The overall changes in NP and PS were primarily driven by the three most abundant species(contributing more than 60%in both years),rather than by shifts in floristic composition.Our findings highlight that vegetation recovery in Bangor alpine steppes following GE relies solely on the expansion of existing patches rather than the recruitment of new ones in interpatch gaps.We recommend prioritizing growth-promoting measures,such as nutrient or water management,over seed addition when assisting with GE for restoring lightly degraded grasslands.展开更多
High-performance magnesium alloys are in great demand to meet the lightweight design requirements of aircraft.Grain size has long been recognized as a key factor influencing the mechanical properties of alloys.This st...High-performance magnesium alloys are in great demand to meet the lightweight design requirements of aircraft.Grain size has long been recognized as a key factor influencing the mechanical properties of alloys.This study investigates the effect of grain size,controlled by Zr addition,on the fatigue behavior of a recently developed low-cost Mg-2.6Nd-0.35Zn alloy,through systematic characterization and analysis of stress-life(S-N)curves,fatigue crack propagation,fracture surface morphology,stress intensity factor,and crack propagation threshold.The results show that after heat treatment(solution at 525±5℃ for 8 h and water quenching at 60-80℃,followed by aging at 250±5℃for 14 h and then air cooling),coarse-grained specimens(average grain size approximately 596μm)containing 0.12wt.%Zr exhibit greater resistance to fatigue crack propagation than fine-grained specimens(average grain size approximately 94μm)containing 0.46wt.%Zr.Coarse grains promote intergranular fracture,while fine grains favor transgranular fracture.In addition,coarse grains reduce the sensitivity of the crack tip to stress concentration.Furthermore,fine-grained samples demonstrate a longer total fatigue life,owing to their superior resistance to crack initiation,which significantly prolongs the crack initiation stage.These findings highlight the importance of optimizing grain size to achieve the best possible fatigue resistance in Mg-Nd-Zn-Zr alloys for practical engineering applications.展开更多
Rock-ice avalanches in cold high-mountain regions pose severe hazards due to their high mobility,yet the quantitative controls of particle-size ratio and ice content remain insufficiently constrained.This study invest...Rock-ice avalanches in cold high-mountain regions pose severe hazards due to their high mobility,yet the quantitative controls of particle-size ratio and ice content remain insufficiently constrained.This study investigates their coupled effects using inclinedflume experiments and Discrete Element Method(DEM)simulations,covering three gravel sizes(2-5 mm,5-7 mm,7-10 mm)and four ice-content levels(0%,20%,40%,60%).Run-out distance,velocity,energy components,flow regime(Savage number),and segregation indexαwere quantified.Increasing ice content significantly enhances mobility,but with diminishing marginal effectiveness.From 0%to 40%ice content,run-out distance increases by 41%-86%,whereas the additional increase from 40%to 60%contributes only 12%-23%.Particle-size ratio strongly governs segregation intensity.Fine-gravel groups reach segregation indices ofα=0.92-0.98,indicating nearly complete upward migration of ice,whereas medium-gravel and coarse-gravel groups exhibit much weaker segregation,stabilizing atα=0.68-0.74 and 0.60-0.69.Savage number analyses reveal marked flow-regime transitions.At 0%ice content,Savage numbers reach 1.0-1.5,indicating a collisional regime.Increasing ice content suppresses collisionality,with Savage numbers decreasing to 0.03-0.07 at 60%ice content,consistent with dense-regime flow.DEM energy analyses confirm this regime shift:for finegravel mixtures,collision energy decreases by 14%,while sliding-friction energy increases by 33%as ice content increases from 0%to 60%,reflecting enhanced overburden effects imposed by upward-segregated ice layers.Medium and coarse mixtures exhibit weaker or opposite energy-shift patterns,demonstrating strong size dependence.Mechanistically,large particle-size contrasts promote strong segregation and form dense basal rock layers that increase basal friction and reduce mobility.When particle sizes are similar or ice content is high,segregation remains limited,allowing ice to mix into the basal layer,thereby reducing basal friction and enhancing mobility.This research quantitatively demonstrates how composition controls particle spatial distribution,flow regime,and energy dissipation,offering new mechanistic insights into the propagation and deposition behaviors of rock-ice avalanches and improving hazard assessment in vulnerable high-mountain regions.展开更多
Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis t...Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.展开更多
The calculation of viewing and solar geometry angles is a critical first step in retrieving atmospheric and surface variables from geostationary satellite observations.Whereas the viewing angles for geostationary sate...The calculation of viewing and solar geometry angles is a critical first step in retrieving atmospheric and surface variables from geostationary satellite observations.Whereas the viewing angles for geostationary satellites are not timevarying,a primary source of inaccuracy in solar positioning is the use of a single timestamp.Since pixel scanning times can differ significantly across the field-of-view disk(e.g.,by approximately 13 min for Fengyun-4B),this practice leads to errors of up to±2°in solar zenith angle,which translates to±50 W m^(−2) in extraterrestrial irradiance;the errors in solar azimuth angle can exceed±100°.Beyond scanning time,this work also quantifies the impact of other inputs—including altitude,surface pressure,air temperature,difference between Terrestrial Time and Universal Time,and atmospheric refraction—on the resulting angles.A comparison of our precise calculations with the official National Satellite Meteorological Center L1_GEO product shows an accuracy within 0.1°,confirming its utility for most retrieval tasks.To facilitate higher precision when required,this work releases the corresponding satellite and solar positioning codes in both R and Python.展开更多
With the development of the semiconductor industry below the 7 nm scale,critical dimension small-angle X-ray scattering(CD-SAXS)has emerged as a powerful tool for quantitatively measuring nanoscale deviations.In this ...With the development of the semiconductor industry below the 7 nm scale,critical dimension small-angle X-ray scattering(CD-SAXS)has emerged as a powerful tool for quantitatively measuring nanoscale deviations.In this study,the effects of X-ray beam size and photon energy on the accuracy of critical dimension measurements were investigated.Critical dimensions measured using beams with different spot sizes showed different deviations from the expected values.Beam sizes that were either too large or too small did not improve confidence intervals.As the incident energy increased,the X-ray transmission rate increased,while the scattering cross section decreased,resulting in a gradual decrease in the signal-to-noise ratio of the diffraction peaks,which reduced the accuracy of the CD-SAXS measurements.An optimal accuracy was obtained at 12 keV with a smaller beam size.Using an effective trapezoid model,the results yielded an average pitch of 100.4±0.2 nm,width of 49.8±0.2 nm,height of 130.0±0.2 nm,and a sidewall angle below 1.1°±0.1°.These results provide crucial guidance for the future development of CD-SAXS laboratories and the construction of X-ray machines as well as robust support for research in related fields.展开更多
In aerospace,nuclear power,and new energy vehicles industries,utilizing integrated metal components with extreme sizes and/or structures is crucial for achieving significant weight-saving,performance-improvement,and e...In aerospace,nuclear power,and new energy vehicles industries,utilizing integrated metal components with extreme sizes and/or structures is crucial for achieving significant weight-saving,performance-improvement,and excellent reliability.These components,made from metal sheets,rings,or tubes,exhibit characteristics like ultra-thin,ultra-thick,ultra-large,ultra-long,ultra-high ribs,and large variable diameters.During plastic de-formation in metal forming processes,defects such as ruptures,wrinkles,excessive strain differences,and un-expected weak performance areas are likely to occur due to the intersection of multiple effects in different research disciplines,including materials science,processes,and mechanics of materials.Consequently,the smooth forming of integrated parts is difficult.It is the first time to review,summarize,and analyze the ad-vancement of forming methods for producing integrated parts with extreme sizes and structures.The general academic ideas to change the process conditions and sequences to optimize stress state and improve plastic deformation ability for forming the components with extreme sizes/structures are introduced.Practical ex-amples,discussed in detail in the paper,include the forming of(i)integrated ultra-thin and ultra-thick sheet components;(ii)integrated ultra-large size ring components with thin wall and high ribs;and(iii)integrated ultra-long tube components with large perimeter difference.Various plasticity technologies and process se-quences have been developed.The key processes and applications of the technologies are discussed in detail,which achieve successful plastic forming of integrated components.This paper provides state-of-the-art and perspectives for the rapidly advancing material forming fields of key metal components for the next generation of equipment.展开更多
Small angle x-ray scattering(SAXS)is an advanced technique for characterizing the particle size distribution(PSD)of nanoparticles.However,the ill-posed nature of inverse problems in SAXS data analysis often reduces th...Small angle x-ray scattering(SAXS)is an advanced technique for characterizing the particle size distribution(PSD)of nanoparticles.However,the ill-posed nature of inverse problems in SAXS data analysis often reduces the accuracy of conventional methods.This article proposes a user-friendly software for PSD analysis,GranuSAS,which employs an algorithm that integrates truncated singular value decomposition(TSVD)with the Chahine method.This approach employs TSVD for data preprocessing,generating a set of initial solutions with noise suppression.A high-quality initial solution is subsequently selected via the L-curve method.This selected candidate solution is then iteratively refined by the Chahine algorithm,enforcing constraints such as non-negativity and improving physical interpretability.Most importantly,GranuSAS employs a parallel architecture that simultaneously yields inversion results from multiple shape models and,by evaluating the accuracy of each model's reconstructed scattering curve,offers a suggestion for model selection in material systems.To systematically validate the accuracy and efficiency of the software,verification was performed using both simulated and experimental datasets.The results demonstrate that the proposed software delivers both satisfactory accuracy and reliable computational efficiency.It provides an easy-to-use and reliable tool for researchers in materials science,helping them fully exploit the potential of SAXS in nanoparticle characterization.展开更多
Bacterial cells are widely accepted as nucleation sites for calcium carbonate precipitation in biomineralization based on the Microbially Induced Carbonate Precipitation(MICP)process.For MICP-based insitu biotreatment...Bacterial cells are widely accepted as nucleation sites for calcium carbonate precipitation in biomineralization based on the Microbially Induced Carbonate Precipitation(MICP)process.For MICP-based insitu biotreatment,the firstproblem to be solved is how to introduce and retain the bacterial cells in the soil,which involves the migration and retention of bacterial cells during the biogrouting process.Soil particle size,a key factor in determining pore throat size,can have a significanteffect on the migration and retention of bacterial cells in the soil and therefore on biomineralization.To investigate the effect of particle size on the migration and retention of bacterial cells in sand and its biomineralization,two sets of tests were carried out in this study,including percolation tests and sand column treatment tests.Soil urease activity(definedas urease activity per unit mass of soil)and calcium carbonate content of the biomineralized sand were measured to comprehensively assess the migration and retention of bacterial cells in the sand.The results indicate that sands with a particle size smaller than 0.25 mmwould inhibit the migration of bacteria in the sand,resulting in a nonuniform distribution of precipitated calcium carbonate and a low strength enhancement of biomineralization.On the other hand,sands with a particle size larger than 1.18 mm are unfavorable for retaining bacterial cells in the sand,resulting in low calcium conversion efficiency.Meanwhile,particle size would also affect the formation of effective calcium carbonate through interparticle contact number and interparticle pore size,and thus biomineralization.展开更多
Long-span bridges are usually constructed over waterways that involve substantial ship traffic,resulting in a risk of collisions between the bridge girders and over-height ships.The consequences of this can be severe ...Long-span bridges are usually constructed over waterways that involve substantial ship traffic,resulting in a risk of collisions between the bridge girders and over-height ships.The consequences of this can be severe structural damage or even collapse.Accurate measurement of ship dimensions is an effective way to monitor approaching over-height ships and avoid collisions.However,the performance of current techniques for estimating the size of moving objects can be undermined by large sensor-to-object distance,limiting their applicability.In this study,we propose a digital twin-assisted ship size measurement framework that can overcome such limitations through a predictive model and virtual-to-real-world transfer learning.Specifically,a 3D synthetic environment is first established to generate a synthetic dataset,which includes ship images,positions,and dimensions.Then the pixel information and spatial coordinates of ships are adopted as regressors,and ship dimensions are selected as the output variables to pre-train deep learning models using the generated dataset.Coordinate system transformations are applied to address dataset bias between the simulated world and real-world,as well as improve the model’s generalization.The pre-trained models are compared using supervised virtual-to-real-world transfer learning to select the version with optimal real-world performance.The mean absolute percentage error is only 3.74%across varying camera-to-ship distances,which demonstrates that the proposed method is effective for over-limit ship monitoring.展开更多
This article refers to the “Mathematics of Harmony” by Alexey Stakhov in 2009, a new interdisciplinary direction of modern science. The main goal of the article is to describe two modern scientific discoveries–New ...This article refers to the “Mathematics of Harmony” by Alexey Stakhov in 2009, a new interdisciplinary direction of modern science. The main goal of the article is to describe two modern scientific discoveries–New Geometric Theory of Phyllotaxis (Bodnar’s Geometry) and Hilbert’s Fourth Problem based on the Hyperbolic Fibonacci and Lucas Functions and “Golden” Fibonacci λ-Goniometry (λ > 0 is a given positive real number). Although these discoveries refer to different areas of science (mathematics and theoretical botany), however they are based on one and the same scientific ideas-the “golden mean,” which had been introduced by Euclid in his Elements, and its generalization—the “metallic means,” which have been studied recently by Argentinian mathematician Vera Spinadel. The article is a confirmation of interdisciplinary character of the “Mathematics of Harmony”, which originates from Euclid’s Elements.展开更多
The study or pore characteristics is or great importance in reservoir evaluation,especially in deeply buried s andstone.It controls the storage mechanism and reservoir fluid properties of the permeable horizons.The fi...The study or pore characteristics is or great importance in reservoir evaluation,especially in deeply buried s andstone.It controls the storage mechanism and reservoir fluid properties of the permeable horizons.The first member of Eocene Shahejie Formation(Esl)sandstone is classified as feldspathic litharenite and lithic arkose.The present research investigates the pore characteristics and reservoir features of the deeply buried sandstone reservoir of Esl member of Shahejie Formation.The techniques including thin-section petrography,mercury injection capillary pressure(MICP),scanning electron microscopy and laser scanning confocal microscope images were used to demarcate the pores including primary intergranular pores and secondary intergranular,intragranular,dissolution and fracture pores.Mercury injection test and routine core analysis were led to demarcate the pore network characteristics of the studied reservoir.Pore size and pore throat size distribution are acquired from mercury injection test.Porosity values range from 0.5%to 30%,and permeability ranges 0.006-7000 mD.Pore radii of coarse-grained sandstone and fine-grained sandstone range from 0.2 to>4μm and 1 nm to 1.60μm,respectively,by MICP analysis.The mineral composition also plays an important role in protecting the pores with pressure from failure.Fractured sandstone and coarse-grained sandstone consist of large and interconnected pores that enhance the reservoir porosity and permeability,whereas fine-grained sandstone and siltstone consist of numerous pores but not well interconnected,and so they consist of high porosity with low permeability.展开更多
The use of coral aggregate concrete(CAC)as a novel construction material has attracted significant attention for the construction of reef engineering structures.To investigate the static splitting-tensile behaviors of...The use of coral aggregate concrete(CAC)as a novel construction material has attracted significant attention for the construction of reef engineering structures.To investigate the static splitting-tensile behaviors of CAC under the influence of two factors,namely specimen geometry and bearing strip size,a three-dimensional(3D)mesoscale modeling approach with consideration for aggregate randomness in shape and distribution was adopted in this study.We established 12 different specimen models with two specimen shapes(i.e.,a cube with an edge length of 150 mm and a cylinder with dimensions ofφ150 mm×300 mm)and six strip widths(i.e.,6,9,12,15,18,and 20 mm)for calculation.The effects of specimen geometry and strip width on the splitting-tensile properties of CAC,such as failure processes,final failure patterns,and splitting-tensile strength(fst),are analyzed and discussed systematically.The results indicate the high reliability of the developed mesoscale modeling approach and reveal the optimal computational parameters for simulating and predicting the splitting-tensile properties of CAC.The fstvalues of CAC are associated with both the specimen geometry and width of the bearing strip.The fstvalues of the cube model are slightly higher than those of the cylinder model for the same bearing strip size,representing geometry effects that can be explained by differences in fracture area.Additionally,the fstvalue of CAC gradually increases with the relative width of the bearing strip ranging from 0.04 to 0.13.Based on the elastic solution theory,the variation area of CAC fstvalues with the relative width of the bearing strip was determined preliminarily,which has great significance for studying the tensile performance of CAC.展开更多
The Bauschinger and size effects in the thinfilm plasticity theory arising from the defect-energy of geometrically necessary dislocations(GNDs)are analytically investigated in this paper.Firstly,this defect-energy is ...The Bauschinger and size effects in the thinfilm plasticity theory arising from the defect-energy of geometrically necessary dislocations(GNDs)are analytically investigated in this paper.Firstly,this defect-energy is deduced based on the elastic interactions of coupling dislocations(or pile-ups)moving on the closed neighboring slip plane.This energy is a quadratic function of the GNDs density,and includes an elastic interaction coefficient and an energetic length scale L.By incorporating it into the work-conjugate strain gradient plasticity theory of Gurtin,an energetic stress associated with this defect energy is obtained,which just plays the role of back stress in the kinematic hardening model.Then this back-stress hardening model is used to investigate the Bauschinger and size effects in the tension problem of single crystal Al films with passivation layers.The tension stress in the film shows a reverse dependence on the film thickness h.By comparing it with discrete-dislocation simulation results,the length scale L is determined,which is just several slip plane spacing,and accords well with our physical interpretation for the defect-energy.The Bauschinger effect after unloading is analyzed by combining this back-stress hardening model with a friction model.The effects of film thickness and pre-strain on the reversed plastic strain after unloading are quantified and qualitatively compared with experiment results.展开更多
基金financial support from the National Natural Science Foundation of China(No.52035012)the Guangdong Basic and Applied Basic Research Foundation(No.2025A1515012203)。
文摘The specific surface area(S S)and pore size(D)exhibit an inherent trade-off in the microscale design of bone implants:larger pores typically correlate with reduced surface area and vice versa.This relationship has attracted notable attention because of its critical role in the regulation of cell adhesion and osteogenesis.However,it remains largely unclear how S S and D affect the generated bone tissue and dynamically change during long-term osteogenesis.Herein,by applying rigorous geometric mapping to minimal surfaces,we constructed precisely partitioned and layer-by-layer thickened tissue models to simulate osteogenesis across different temporal scales and thereby track the dynamic evolution of geometric characteristics,permeability,and mechanobiological tissue differentiation.The high-S S samples were found to facilitate the rapid formation of new bone tissue in the early stages.However,their smaller pores tended to cause occlusions,hindering further tissue development.In contrast,low-S S samples showed slower bone regeneration,but their larger pores provided adequate physical space for tissue regeneration and mass transport,ultimately promoting bone formation in the long term.Mechanobiological regulation suggests that fibrous tissue formation inhibits additional bone formation,establishing a dynamic equilibrium between osteogenesis and pore space to sustain nutrient/waste exchange throughout the regenerative process.Overall,smaller pores are preferable in implants for minimally loaded osteoplasty procedures focused on early-stage bone consolidation,whereas larger pores are preferable in dynamically loaded implants requiring prolonged mechanical stability.
基金supported in part by financial support from the National Key R&D Program of China(No.2023YFB3407003)the National Natural Science Foundation of China(No.52375378).
文摘A new analytical model for geometric size and forming force prediction in incremental flanging(IF)is presented in this work.The complex deformation characteristics of IF are considered in the modeling process,which can accurately describe the strain and stress states in IF.Based on strain analysis,the model can predict the material thickness distribution and neck height after IF.By considering contact area,strain characteristics,material thickness changes,and friction,the model can predict specific moments and corresponding values of maximum axial forming force and maximum horizontal forming force during IF.In addition,an IF experiment involving different tool diameters,flanging diameters,and opening hole diameters is conducted.On the basis of the experimental strain paths,the strain characteristics of different deformation zones are studied,and the stable strain ratio is quantitatively described through two dimensionless parameters:relative tool diameter and relative hole diameter.Then,the changing of material thickness and forming force in IF,and the variation of minimum material thickness,neck height,maximum axial forming force,and maximum horizontal forming force with flanging parameters are studied,and the reliability of the analytical model is verified in this process.Finally,the influence of the horizontal forming force on the tool design and the fluctuation of the forming force are explained.
基金supported by the European Union’s Horizon Europe research and innovation programme,Zero Emission electric Vehicles enabled by haRmonised circularity,under No.101138034.
文摘Grain size and formation of the Peripheral Coarse Grain(PCG)defect influence the mechanical and crash properties of extruded profiles.Controlling microstructural evolution during the extrusion of 6XXX series aluminum alloys is therefore essential to ensure the performance of structural components.In this work,three profiles with the same nominal geometry were extruded with a die comprising three different bearing geometries to create different extrusion conditions.Each profile was analyzed experimentally to gather data on the microstructure and mechanical properties.Bulge testing revealed that Profile 2,with the thickest PCG layer(490-1150µm),exhibited worse mechanical performance,with a hoop strain at fracture of 0.08 and a peak load of 51.5 kN,compared to Profiles 1 and 3,which had higher hoop strains(0.13 and 0.14)and peak loads(56.1 and 57.6 kN,respectively).Finite Element Method(FEM)simulations of the extrusion process were carried out using Qform Extrusion UK with a post-processing subroutine developed and implemented to calculate additional parameters such as the stored energy,percentage dynamic recrystallization,grain size,and PCG formation based on standard output parameters from the simulation including strain,temperature and strain rate.The simulation demonstrated that the highest strain rate(40-220 s^(-1))and stored energy(150,000-440,000 J m^(-3))in Profile 2 led to the thickest PCG layer.Based on these results,the proposed predictive model was validated against experimental data,demonstrating high accuracy in predicting PCG thickness and grain size while effectively capturing the influence of process parameters on microstructural evolution.
基金the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project under Grant 2024ZD1000500。
文摘The shallow slip deficit(SSD)during strike-slip earthquakes raises a question of how the strain budget is accommodated over multiple cycles.However,the origin of variable SSD observed in different earthquakes is still under debate because each earthquake has its unique initial stress condition.Here,we derive the slip model of the 2021 M W 7.4 Maduo earthquake in Qinghai,China,using multi-track radar images.Our results revealed that,in contrast to the large SSD on segments close to the epicenter,a much smaller SSD was observed at the west terminus of the rupture,where aftershock distribution indicates that the fault changes dip direction at 6 km depth.The 2021 Maduo earthquake thus represents an extraordinary case of significant along-strike SSD variation.After accounting for interseismic,postseismic,and diffuse off-fault deformation,we find that this variation is likely contributed by the along-dipping geometrical variation,implying that a multi-segment earthquake may leave heterogeneous stress condition on the fault with different amounts of SSD.
基金Project supported by Quantum Science and Technology–National Science and Technology Major Project(Grant No.2024ZD0301000)the National Natural Science Foundation of China(Grant No.12305031)+1 种基金the Hangzhou Joint Fund of the Natural Science Foundation of Zhejiang Province,China(Grant No.LHZSD24A050001)the Science Foundation of Zhejiang Sci-Tech University(Grant Nos.23062088Y and 23062153-Y)。
文摘The Wilczek–Zee connection(WZC)is a key concept in the study of topology of quantum systems.Here,we introduce the double Wilczek–Zee connection(DWZC)which naturally appears in the pure-state quantum geometric tensor(QGT),another important concept in the field of quantum geometry.The DWZC is Hermitian with respect to the two integer indices,just like the original Hermitian WZC.Based on the symmetric logarithmic derivative operator,we propose a mixed-state quantum geometric tensor.Using the symmetric properties of the DWZC,we find that the real part of the QGT is connected to the real part of the DWZC and the square of eigenvalue differences of the density matrix,whereas the imaginary part can be given in terms of the imaginary part of the DWZC and the cube of the eigenvalue differences.For density matrices with full rank or no full rank,the QGT can be given in terms of real and imaginary parts of the DWZC.
基金Project supported by the National Natural Science Foundation of China(No.12472077)the supports from Shanghai Gaofeng Project for University Academic Program Development,Fundamental Research Funds for the Central Universities(No.22120240353).
文摘Lattice materials have demonstrated promising potential in engineering applications owing to their exceptional lightweight,high specific strength,and tunable mechanical properties.However,the traditional homogenization methods based on the classical elasticity theory struggle to accurately describe the non-classical mechanical behaviors of lattice materials,especially when dealing with complex unit-cell geometries featured by non-symmetric configurations or non-single central node connections.In response to this limitation,this study establishes a generalized homogenization model based on the micropolar theory framework,employing Hill's boundary conditions to precisely predict the equivalent moduli of complex lattice materials.By introducing the independent rotational degree of freedom(DOF)characteristic of the micropolar theory,the proposed model successfully overcomes the limitation of conventional methods in accurately describing the asymmetric deformation and scale effects.We initially calculate the constitutive relations of two-dimensional(2D)cross-shaped multi-node chiral lattices and subsequently extend the method to three-dimensional(3D)lattices,successfully predicting the mechanical properties of both traditional and eccentric body-centered cubic(BCC)lattices.The theoretical model is validated through the finite element numerical verification which shows excellent consistency with the theoretical predictions.A further parametric study investigates the influence of geometric parameters,revealing the underlying size-effect mechanism.This paper provides a reliable theoretical tool for the design and property optimization of complex lattice materials.
基金financially supported by the Science and Technology Bureau of Ali Prefecture,project named“Assessing the Carbon Sequestration and Carbon Sink Enhancement Potential of Natural Ecosystems in Ali Region(QYXTZX-AL2022-05)”。
文摘The alpine grassland vegetation on the Qinghai-Tibet Plateau is composed of plant patches in varied sizes.It remains uncertain whether vegetation recovery following grazing exclusion(GE)in degraded grasslands is driven by increases in patches number(NP),patch size(PS),or both.We based our predictions on two hypotheses:GE intensifies plant competition,and facilitation prevails near patches while competition prevails in interpatch spaces.We predicted that the NP would remain stable or decrease and PS would increase under GE treatment.To evaluate these predictions,we conducted a study in six lightly degraded alpine grasslands under free grazing(FG)conditions in Bangor County,Xizang Autonomous Region,China,with corresponding GE treatments using transects in 2017 and 2018.Results revealed that four sites in 2017 and five sites in 2018 had reduced NP and increased PS,with probabilities of 0.033(2017)and 0.004(2018),respectively,and a joint probability of 0.0001 under the null hypothesis that GE does not affect NP or PS.The NP reduction was solely due to the decrease in small patch sizes.An increase in PS was common across species,and a predominant tendency for NP reduction was observed among species across the sites.The overall changes in NP and PS were primarily driven by the three most abundant species(contributing more than 60%in both years),rather than by shifts in floristic composition.Our findings highlight that vegetation recovery in Bangor alpine steppes following GE relies solely on the expansion of existing patches rather than the recruitment of new ones in interpatch gaps.We recommend prioritizing growth-promoting measures,such as nutrient or water management,over seed addition when assisting with GE for restoring lightly degraded grasslands.
文摘High-performance magnesium alloys are in great demand to meet the lightweight design requirements of aircraft.Grain size has long been recognized as a key factor influencing the mechanical properties of alloys.This study investigates the effect of grain size,controlled by Zr addition,on the fatigue behavior of a recently developed low-cost Mg-2.6Nd-0.35Zn alloy,through systematic characterization and analysis of stress-life(S-N)curves,fatigue crack propagation,fracture surface morphology,stress intensity factor,and crack propagation threshold.The results show that after heat treatment(solution at 525±5℃ for 8 h and water quenching at 60-80℃,followed by aging at 250±5℃for 14 h and then air cooling),coarse-grained specimens(average grain size approximately 596μm)containing 0.12wt.%Zr exhibit greater resistance to fatigue crack propagation than fine-grained specimens(average grain size approximately 94μm)containing 0.46wt.%Zr.Coarse grains promote intergranular fracture,while fine grains favor transgranular fracture.In addition,coarse grains reduce the sensitivity of the crack tip to stress concentration.Furthermore,fine-grained samples demonstrate a longer total fatigue life,owing to their superior resistance to crack initiation,which significantly prolongs the crack initiation stage.These findings highlight the importance of optimizing grain size to achieve the best possible fatigue resistance in Mg-Nd-Zn-Zr alloys for practical engineering applications.
基金funded by the Natural Science Foundation of China(Grants No 42277127)。
文摘Rock-ice avalanches in cold high-mountain regions pose severe hazards due to their high mobility,yet the quantitative controls of particle-size ratio and ice content remain insufficiently constrained.This study investigates their coupled effects using inclinedflume experiments and Discrete Element Method(DEM)simulations,covering three gravel sizes(2-5 mm,5-7 mm,7-10 mm)and four ice-content levels(0%,20%,40%,60%).Run-out distance,velocity,energy components,flow regime(Savage number),and segregation indexαwere quantified.Increasing ice content significantly enhances mobility,but with diminishing marginal effectiveness.From 0%to 40%ice content,run-out distance increases by 41%-86%,whereas the additional increase from 40%to 60%contributes only 12%-23%.Particle-size ratio strongly governs segregation intensity.Fine-gravel groups reach segregation indices ofα=0.92-0.98,indicating nearly complete upward migration of ice,whereas medium-gravel and coarse-gravel groups exhibit much weaker segregation,stabilizing atα=0.68-0.74 and 0.60-0.69.Savage number analyses reveal marked flow-regime transitions.At 0%ice content,Savage numbers reach 1.0-1.5,indicating a collisional regime.Increasing ice content suppresses collisionality,with Savage numbers decreasing to 0.03-0.07 at 60%ice content,consistent with dense-regime flow.DEM energy analyses confirm this regime shift:for finegravel mixtures,collision energy decreases by 14%,while sliding-friction energy increases by 33%as ice content increases from 0%to 60%,reflecting enhanced overburden effects imposed by upward-segregated ice layers.Medium and coarse mixtures exhibit weaker or opposite energy-shift patterns,demonstrating strong size dependence.Mechanistically,large particle-size contrasts promote strong segregation and form dense basal rock layers that increase basal friction and reduce mobility.When particle sizes are similar or ice content is high,segregation remains limited,allowing ice to mix into the basal layer,thereby reducing basal friction and enhancing mobility.This research quantitatively demonstrates how composition controls particle spatial distribution,flow regime,and energy dissipation,offering new mechanistic insights into the propagation and deposition behaviors of rock-ice avalanches and improving hazard assessment in vulnerable high-mountain regions.
基金Under the auspices of the General Project of Science and Technology Department of Shaanxi Province(No.2023-JCYB-264)General Program of National Natural Science Foundation of China(No.41801004,42371008,42471012)。
文摘Riparian dunes in deserts exhibit unique geographic features due to aeolian-fluvial interactions.In this study,we collected 510 surface sediment samples from eight drainage basins and conducted a systematic analysis to examine the grain size characteristics of major riparian dunes in the typical cold and arid deserts of China.The results indicate that major riparian dunes of deserts in study area can be classified into three types based on their grain size characteristics.The Bartlett test of sphericity and the Kaiser-Meyer-Olkin(KMO)test were also performed,and their significance values were found to be 0.000 and 0.584,respectively.The results of the principal component analysis revealed that the cumulative contribution rate of the total variance reached 85.9%for the two principal components with characteristic roots greater than 1.0.The primary principal component included medium sand,whereas the secondary principal component included fine sand.We conducted a cluster analysis and classified the samples into three major types.Type I rivers include the Keriya River,Langqu River,Tora River and Heihe River,which are characterized by by fine particle size,and well-sorted.Type II includes Mu Bulag River,Kuye River,and the Xar Moron River,Compared with type I,it has a relatively coarser mean grain size and relatively poor sorting for this type.Type III includes the Maquan River,which is characterized mainly by fine sand and medium sand,accounting for more than 90%,and the sorting coefficient(0.52)suggests relatively well sorting in this pattern.Moreover,principal component analysis was applied to determine the particle sizes of samples from different watersheds.Moreover,these sediments exhibit both hydromorphic and aeolian features.At the drainage basin scale,the mode and intensity of aeolian-fluvial interactions depend on climatic conditions.In arid and semi-arid climate regions,wind is the dominant force,and the grain size exhibits significant aeolian features.Conversely,in the semi-humid region,flowing water is the dominant force,and riparian dunes in this region are formed by aeolian-fluvial interaction.The angle between the wind direction and flow direction in different reaches influences both the supply of sediment sources and the development of riparian dunes.This study will provide a new perspective for evaluating aeolian-fluvial interactions on riparian dunes in the deserts of China’s cold and arid regions.
基金supported by the National Natural Science Foundation of China(Grant No.42375192).
文摘The calculation of viewing and solar geometry angles is a critical first step in retrieving atmospheric and surface variables from geostationary satellite observations.Whereas the viewing angles for geostationary satellites are not timevarying,a primary source of inaccuracy in solar positioning is the use of a single timestamp.Since pixel scanning times can differ significantly across the field-of-view disk(e.g.,by approximately 13 min for Fengyun-4B),this practice leads to errors of up to±2°in solar zenith angle,which translates to±50 W m^(−2) in extraterrestrial irradiance;the errors in solar azimuth angle can exceed±100°.Beyond scanning time,this work also quantifies the impact of other inputs—including altitude,surface pressure,air temperature,difference between Terrestrial Time and Universal Time,and atmospheric refraction—on the resulting angles.A comparison of our precise calculations with the official National Satellite Meteorological Center L1_GEO product shows an accuracy within 0.1°,confirming its utility for most retrieval tasks.To facilitate higher precision when required,this work releases the corresponding satellite and solar positioning codes in both R and Python.
基金supported by the National Natural Science Foundation of China(No.12175295)the National Key R&D Program of China(2021YFA1601000)the Shanghai Municipal Science and Technology Major Project。
文摘With the development of the semiconductor industry below the 7 nm scale,critical dimension small-angle X-ray scattering(CD-SAXS)has emerged as a powerful tool for quantitatively measuring nanoscale deviations.In this study,the effects of X-ray beam size and photon energy on the accuracy of critical dimension measurements were investigated.Critical dimensions measured using beams with different spot sizes showed different deviations from the expected values.Beam sizes that were either too large or too small did not improve confidence intervals.As the incident energy increased,the X-ray transmission rate increased,while the scattering cross section decreased,resulting in a gradual decrease in the signal-to-noise ratio of the diffraction peaks,which reduced the accuracy of the CD-SAXS measurements.An optimal accuracy was obtained at 12 keV with a smaller beam size.Using an effective trapezoid model,the results yielded an average pitch of 100.4±0.2 nm,width of 49.8±0.2 nm,height of 130.0±0.2 nm,and a sidewall angle below 1.1°±0.1°.These results provide crucial guidance for the future development of CD-SAXS laboratories and the construction of X-ray machines as well as robust support for research in related fields.
基金Supported by National Natural Science Foundation of China(Grant Nos.52422510,52373320,52175360,50725517)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(Grant No.2021QNRC001)+1 种基金the Key R&D Program of Hubei Province(Grant No.2024BAB080)Natural Science Foundation of Wuhan(Grant No.2024040801020257).
文摘In aerospace,nuclear power,and new energy vehicles industries,utilizing integrated metal components with extreme sizes and/or structures is crucial for achieving significant weight-saving,performance-improvement,and excellent reliability.These components,made from metal sheets,rings,or tubes,exhibit characteristics like ultra-thin,ultra-thick,ultra-large,ultra-long,ultra-high ribs,and large variable diameters.During plastic de-formation in metal forming processes,defects such as ruptures,wrinkles,excessive strain differences,and un-expected weak performance areas are likely to occur due to the intersection of multiple effects in different research disciplines,including materials science,processes,and mechanics of materials.Consequently,the smooth forming of integrated parts is difficult.It is the first time to review,summarize,and analyze the ad-vancement of forming methods for producing integrated parts with extreme sizes and structures.The general academic ideas to change the process conditions and sequences to optimize stress state and improve plastic deformation ability for forming the components with extreme sizes/structures are introduced.Practical ex-amples,discussed in detail in the paper,include the forming of(i)integrated ultra-thin and ultra-thick sheet components;(ii)integrated ultra-large size ring components with thin wall and high ribs;and(iii)integrated ultra-long tube components with large perimeter difference.Various plasticity technologies and process se-quences have been developed.The key processes and applications of the technologies are discussed in detail,which achieve successful plastic forming of integrated components.This paper provides state-of-the-art and perspectives for the rapidly advancing material forming fields of key metal components for the next generation of equipment.
基金Project supported by the Project of the Anhui Provincial Natural Science Foundation(Grant No.2308085MA19)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA0410401)+2 种基金the National Natural Science Foundation of China(Grant No.52202120)the National Key Research and Development Program of China(Grant No.2023YFA1609800)USTC Research Funds of the Double First-Class Initiative(Grant No.YD2310002013)。
文摘Small angle x-ray scattering(SAXS)is an advanced technique for characterizing the particle size distribution(PSD)of nanoparticles.However,the ill-posed nature of inverse problems in SAXS data analysis often reduces the accuracy of conventional methods.This article proposes a user-friendly software for PSD analysis,GranuSAS,which employs an algorithm that integrates truncated singular value decomposition(TSVD)with the Chahine method.This approach employs TSVD for data preprocessing,generating a set of initial solutions with noise suppression.A high-quality initial solution is subsequently selected via the L-curve method.This selected candidate solution is then iteratively refined by the Chahine algorithm,enforcing constraints such as non-negativity and improving physical interpretability.Most importantly,GranuSAS employs a parallel architecture that simultaneously yields inversion results from multiple shape models and,by evaluating the accuracy of each model's reconstructed scattering curve,offers a suggestion for model selection in material systems.To systematically validate the accuracy and efficiency of the software,verification was performed using both simulated and experimental datasets.The results demonstrate that the proposed software delivers both satisfactory accuracy and reliable computational efficiency.It provides an easy-to-use and reliable tool for researchers in materials science,helping them fully exploit the potential of SAXS in nanoparticle characterization.
基金support by the National Natural Science Foundation of China(NSFC)(Grant Nos.52178319,42477160,52338007).
文摘Bacterial cells are widely accepted as nucleation sites for calcium carbonate precipitation in biomineralization based on the Microbially Induced Carbonate Precipitation(MICP)process.For MICP-based insitu biotreatment,the firstproblem to be solved is how to introduce and retain the bacterial cells in the soil,which involves the migration and retention of bacterial cells during the biogrouting process.Soil particle size,a key factor in determining pore throat size,can have a significanteffect on the migration and retention of bacterial cells in the soil and therefore on biomineralization.To investigate the effect of particle size on the migration and retention of bacterial cells in sand and its biomineralization,two sets of tests were carried out in this study,including percolation tests and sand column treatment tests.Soil urease activity(definedas urease activity per unit mass of soil)and calcium carbonate content of the biomineralized sand were measured to comprehensively assess the migration and retention of bacterial cells in the sand.The results indicate that sands with a particle size smaller than 0.25 mmwould inhibit the migration of bacteria in the sand,resulting in a nonuniform distribution of precipitated calcium carbonate and a low strength enhancement of biomineralization.On the other hand,sands with a particle size larger than 1.18 mm are unfavorable for retaining bacterial cells in the sand,resulting in low calcium conversion efficiency.Meanwhile,particle size would also affect the formation of effective calcium carbonate through interparticle contact number and interparticle pore size,and thus biomineralization.
基金supported by the National Natural Science Foundation of China(Nos.52338011 and 52108274)the Start-up Research Fund of Southeast University(No.RF1028624058),Chinasupport from the SEU Innovation Capability Enhancement Plan for Doctoral Students(No.CXJH_SEU 26112),China.
文摘Long-span bridges are usually constructed over waterways that involve substantial ship traffic,resulting in a risk of collisions between the bridge girders and over-height ships.The consequences of this can be severe structural damage or even collapse.Accurate measurement of ship dimensions is an effective way to monitor approaching over-height ships and avoid collisions.However,the performance of current techniques for estimating the size of moving objects can be undermined by large sensor-to-object distance,limiting their applicability.In this study,we propose a digital twin-assisted ship size measurement framework that can overcome such limitations through a predictive model and virtual-to-real-world transfer learning.Specifically,a 3D synthetic environment is first established to generate a synthetic dataset,which includes ship images,positions,and dimensions.Then the pixel information and spatial coordinates of ships are adopted as regressors,and ship dimensions are selected as the output variables to pre-train deep learning models using the generated dataset.Coordinate system transformations are applied to address dataset bias between the simulated world and real-world,as well as improve the model’s generalization.The pre-trained models are compared using supervised virtual-to-real-world transfer learning to select the version with optimal real-world performance.The mean absolute percentage error is only 3.74%across varying camera-to-ship distances,which demonstrates that the proposed method is effective for over-limit ship monitoring.
文摘This article refers to the “Mathematics of Harmony” by Alexey Stakhov in 2009, a new interdisciplinary direction of modern science. The main goal of the article is to describe two modern scientific discoveries–New Geometric Theory of Phyllotaxis (Bodnar’s Geometry) and Hilbert’s Fourth Problem based on the Hyperbolic Fibonacci and Lucas Functions and “Golden” Fibonacci λ-Goniometry (λ > 0 is a given positive real number). Although these discoveries refer to different areas of science (mathematics and theoretical botany), however they are based on one and the same scientific ideas-the “golden mean,” which had been introduced by Euclid in his Elements, and its generalization—the “metallic means,” which have been studied recently by Argentinian mathematician Vera Spinadel. The article is a confirmation of interdisciplinary character of the “Mathematics of Harmony”, which originates from Euclid’s Elements.
基金funded by the Natural Science Foundation of China Project(No.41602138)National Science and Technology Special Grant(No.2016ZX05006007)+1 种基金China Postdoctoral Science Foundation-funded Project(2015M580617,2017T100524)the Fundamental Research Funds for the Central Universities(15CX08001A)
文摘The study or pore characteristics is or great importance in reservoir evaluation,especially in deeply buried s andstone.It controls the storage mechanism and reservoir fluid properties of the permeable horizons.The first member of Eocene Shahejie Formation(Esl)sandstone is classified as feldspathic litharenite and lithic arkose.The present research investigates the pore characteristics and reservoir features of the deeply buried sandstone reservoir of Esl member of Shahejie Formation.The techniques including thin-section petrography,mercury injection capillary pressure(MICP),scanning electron microscopy and laser scanning confocal microscope images were used to demarcate the pores including primary intergranular pores and secondary intergranular,intragranular,dissolution and fracture pores.Mercury injection test and routine core analysis were led to demarcate the pore network characteristics of the studied reservoir.Pore size and pore throat size distribution are acquired from mercury injection test.Porosity values range from 0.5%to 30%,and permeability ranges 0.006-7000 mD.Pore radii of coarse-grained sandstone and fine-grained sandstone range from 0.2 to>4μm and 1 nm to 1.60μm,respectively,by MICP analysis.The mineral composition also plays an important role in protecting the pores with pressure from failure.Fractured sandstone and coarse-grained sandstone consist of large and interconnected pores that enhance the reservoir porosity and permeability,whereas fine-grained sandstone and siltstone consist of numerous pores but not well interconnected,and so they consist of high porosity with low permeability.
基金financial support from the National Natural Science Foundation of China(52178190,51878350,11832013,51678304,and 52078250)the Science and Technology on Near-Surface Detection Laboratory pre-research Fund(6142414200505)+1 种基金the Interdisciplinary Innovation Foundation for Graduates,Nanjing University of Aeronautics and Astronautics(NUAA)Grant(KXKCXJJ202005)The support provided by the China Scholarship Council(202006830096)during a visit of Zhangyu Wu to University College London is also sincerely acknowledged。
文摘The use of coral aggregate concrete(CAC)as a novel construction material has attracted significant attention for the construction of reef engineering structures.To investigate the static splitting-tensile behaviors of CAC under the influence of two factors,namely specimen geometry and bearing strip size,a three-dimensional(3D)mesoscale modeling approach with consideration for aggregate randomness in shape and distribution was adopted in this study.We established 12 different specimen models with two specimen shapes(i.e.,a cube with an edge length of 150 mm and a cylinder with dimensions ofφ150 mm×300 mm)and six strip widths(i.e.,6,9,12,15,18,and 20 mm)for calculation.The effects of specimen geometry and strip width on the splitting-tensile properties of CAC,such as failure processes,final failure patterns,and splitting-tensile strength(fst),are analyzed and discussed systematically.The results indicate the high reliability of the developed mesoscale modeling approach and reveal the optimal computational parameters for simulating and predicting the splitting-tensile properties of CAC.The fstvalues of CAC are associated with both the specimen geometry and width of the bearing strip.The fstvalues of the cube model are slightly higher than those of the cylinder model for the same bearing strip size,representing geometry effects that can be explained by differences in fracture area.Additionally,the fstvalue of CAC gradually increases with the relative width of the bearing strip ranging from 0.04 to 0.13.Based on the elastic solution theory,the variation area of CAC fstvalues with the relative width of the bearing strip was determined preliminarily,which has great significance for studying the tensile performance of CAC.
基金supported by the National Natural Science Foundation of China(10772096)
文摘The Bauschinger and size effects in the thinfilm plasticity theory arising from the defect-energy of geometrically necessary dislocations(GNDs)are analytically investigated in this paper.Firstly,this defect-energy is deduced based on the elastic interactions of coupling dislocations(or pile-ups)moving on the closed neighboring slip plane.This energy is a quadratic function of the GNDs density,and includes an elastic interaction coefficient and an energetic length scale L.By incorporating it into the work-conjugate strain gradient plasticity theory of Gurtin,an energetic stress associated with this defect energy is obtained,which just plays the role of back stress in the kinematic hardening model.Then this back-stress hardening model is used to investigate the Bauschinger and size effects in the tension problem of single crystal Al films with passivation layers.The tension stress in the film shows a reverse dependence on the film thickness h.By comparing it with discrete-dislocation simulation results,the length scale L is determined,which is just several slip plane spacing,and accords well with our physical interpretation for the defect-energy.The Bauschinger effect after unloading is analyzed by combining this back-stress hardening model with a friction model.The effects of film thickness and pre-strain on the reversed plastic strain after unloading are quantified and qualitatively compared with experiment results.
