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Branch architecture of Tetraena mongolica Maxim. controls particle size distribution of nebkha sediments 认领 引用
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作者 ZHAI Bo DANG Xiaohong +3 位作者 LIU Jing LIU Xiangjie CHEN Xiaona LIU Yajing 《Journal of Arid Land》 SCIE CAS CSCD 2026年第5期851-867,共17页
The formation of desert shrub sand piles(nebkhas)is attributed to the obstruction and subsequent deposition of migrating sand by the shrub itself.However,the relationship between sediment particle size distribution an... The formation of desert shrub sand piles(nebkhas)is attributed to the obstruction and subsequent deposition of migrating sand by the shrub itself.However,the relationship between sediment particle size distribution and shrub branch architecture remains inadequately understood.In August 2020,field investigations were conducted on Tetraena mongolica Maxim.shrubs in the Bayan Engger Desert Nature Reserve,located on the Ordos Plateau in Inner Mongolia Autonomous Region,China.Crown morphological parameters of T.mongolica shrubs and associated nebkhas were systematically measured alongside branch architectures.A one-way analysis of variance(ANOVA)was used to identify differences in branch architectures among various levels,while correlation analysis and model fitting were applied to establish the relationship between crown and nebkha morphological parameters.Path analysis was utilized to identify the key branch architectures that influence crown development.Furthermore,sediment redistribution characteristics of nebkhas were quantified,and principal component analysis combined with regression models was utilized to elucidate the contributions of key branch architectures and sensitive particle size fractions to nebkha deposition.Results indicated that the step-by-step branch ratio(SBR)initially increased from the lower branches to the outermost branches before subsequently decreasing.Additionally,branch angle significantly increased(P<0.0500),whereas both the branch length and the ratio of branch diameters(RBD)significantly decreased toward the exterior of the shrub(P<0.0500).Expansion of crown area significantly enhanced nebkha volume,demonstrating a strong linear relationship(P<0.0010).As the primary contact surface for trapping wind-blown sand,the silhouette area of the shrub initially increased and then decreased from bottom to top.Notably,the silhouette area of the 10-30 cm height layer played a crucial role in promoting nebkha volume expansion(P<0.0100).Path analysis further revealed that the key branch architectures promoting crown area expansion were the step-by-step branch ratio between the third-level and fourth-level branches(SBR3:4),followed by the fourth-level branch length(BLL4),the third-level branch angle(BAL3),and the ratio of branch diameters between the fourth-level and third-level branches(RBD4:3).Under the continuous interception of sediments by branches and leaves,the proportion of surface sediment with a particle size of 100.00-250.00μm reached 51.07%,indicating a significant increase in fine-sized particles.Further analysis confirmed that SBR3:4,BLL4,BAL3,and sediments within the 50.00-100.00μm particle size range were the primary contributors to nebkha deposition.These results demonstrate that the branch characteristics of T.mongolica shrubs near the ground surface promote fine sediment accumulation and nebkha development by regulating crown expansion.The findings reveal the unique adaptation mechanisms of rare and endangered plants in nebkha microhabitats and provide a scientific basis for ecological windbreak and sand-fixation projects in the desert transition zones of arid and semi-arid regions. 展开更多
关键词 Tetraena mongolica Maxim. nebkhas branch architecture particle size distribution nebkha formation Ordos Plateau
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Particle-size distribution and respiratory deposition of airborne pathogens and antimicrobial resistance risk determinants in wastewater treatment plants 认领 引用
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作者 Shanshan Gao Shaobin Li +4 位作者 Yajie Guo Qiaolin Xu Mo Chen Min Gao Xuming Wang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2026年第8期752-762,共11页
Air in wastewater treatment plants(WWTPs)contains high concentrations of pathogens and antimicrobial resistance determinants(ARDs).However,limited information on their particle-size distribution hinders assessment of ... Air in wastewater treatment plants(WWTPs)contains high concentrations of pathogens and antimicrobial resistance determinants(ARDs).However,limited information on their particle-size distribution hinders assessment of occupational inhalation exposure risks in WWTPs.In this study,air samples above the aeration tanks and the secondary sedimentation tanks of WWTPs were collected using Anderson eight-stage air samplers,and the size-resolved bacterial community was characterized by 16S rRNA gene sequencing.The inhalation deposition of ARDs and pathogens in the human respiratory tract was quantitatively evaluated by droplet digital PCR.Results showed that airborne bacterial concentrations above the aeration tank increased with particle size,ranging from 2914 to 5645 copies/m3.By contrast,concentrations above the secondary sedimentation tank exhibited a bimodal distribution,with peaks at 5.8-9.0μm(5592 copies/m3)and 0.65-1.1μum(5302 copies/m3).The most prevalent airborne antibiotic resistance genes were tetW and floR,associated with aerodynamic diameters of 2.64μm and 3.43μm,respectively.The International Commission on Radiological Protection deposition model indicated that airborne pathogens and ARDs were primarily deposited in the upper respiratory tract(17.73-165.63 copies/h)and alveoli(1.84-14.63 copies/h).Notably,deposition densities of Escherichia coli and Enterococcus faecium reached 2.26-36.20 copies/hand 1.62-31.31 copies/h,respectively.Co-occurrence of these pathogens with floR and sulⅡin fine particulate matter may pose significant health risks.This study elucidates the size distribution and respiratory deposition behavior of ARDs and pathogens in WWTP air,addressing critical knowledge gaps for comprehensive assessment of airborne antimicrobial resistance and associated occupational health risks. 展开更多
关键词 Particle size distribution Respiratory deposition Antimicrobial resistance risk determinants(ARDs) Pathogen Wastewater treatment plants(WWTPs)
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FragSAM:Near real-time rock fragment segmentation for size distribution analysis across diverse engineering domains 认领 引用
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作者 Yudi Tang Yulin Wang +4 位作者 Jixiong Zhang Runzhe Hu Changwei Wang Joung Oh Guangyao Si 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2026年第6期1167-1188,共22页
Rock fragment size distribution(FSD)plays an important role in various engineering applications,such as mining,tunnelling,and other underground construction scenarios.While vision-based deep learning approaches have b... Rock fragment size distribution(FSD)plays an important role in various engineering applications,such as mining,tunnelling,and other underground construction scenarios.While vision-based deep learning approaches have been increasingly applied to FSD analysis,they are often case-specific,showing limited cross-site generalization despite their accuracy.To address these challenges,FragSAM,an end-to-end,fully automated framework is proposed for near real-time rock fragment segmentation and FSD analysis across diverse engineering environments.FragSAM integrates the generalization power of Segment Anything Model(SAM)with a context-aware prompting mechanism and lightweight architecture for efficient dense fragment segmentation.In Stage 1,an enhanced SAM automatically generates high-quality annotations,which are used to train a modified CenterNet for precise centroid prediction.In Stage 2,these centroids serve as prompts for EdgeSAM,a lightweight SAM variant optimized for real-time inference.This two-stage design eliminates dense grid prompting and reduces reliance on heavy postprocessing,enabling efficient and scalable segmentation.Experimental results show that FragSAM achieves competitive segmentation performance with significantly lower latency and model complexity compared to existing SAM-based methods.In comparison with supervised learning approaches,it also demonstrates superior generalization and performs better in low-quality or unseen scenarios.Furthermore,case studies on blasting fragmentation,TBM muck,and coastal rock surfaces confirm its robustness and seamless cross-site adaptability,requiring no tuning or retraining,making it highly practical for on-site applications. 展开更多
关键词 Segment anything model Rock fragment size distribution FragSAM Prompt-based vision models Near real-time segmentation
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Impact of seepage on the breaching of non-cohesive landslide dams with different grain size distributions 认领 引用
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作者 QIN Tao YANG Xingguo +2 位作者 ZHOU Jiawen XIANG Shenghao LIAO Haimei 《Journal of Mountain Science》 SCIE CSCD 2026年第2期706-722,共17页
Landslide dams often undergo seepage due to poor particle gradation and loose structure,yet most existing studies focus solely on overtopping-induced breaching mechanisms,neglecting the potential influence of pre-brea... Landslide dams often undergo seepage due to poor particle gradation and loose structure,yet most existing studies focus solely on overtopping-induced breaching mechanisms,neglecting the potential influence of pre-breaching seepage.Seepage may alter the dam's erodibility,structural stability,and material composition,thereby affecting the overtopping breaching process.Through flume experiments,this study investigates the breaching mechanisms of cohesionless landslide dams with different gradations within the same particle size range under coupled seepage-overtopping conditions.The results demonstrate that pre-breaching seepage significantly impacts breaching dynamics.Within a specific particle size range,compared to pure overtopping,seepage reduces downstream slope stability,increases material erodibility,shortens breaching duration,amplifies peak discharge,and advances the timing of peak flow.As the median particle size(D50)increases,the amplification effect of seepage on peak discharge initially increases then decreases,the advancement of peak flow timing diminishes,and the breach erosion rate declines.When D50is sufficiently large,seepage has negligible effects on breach development.For smaller D50,seepage markedly accelerates breach widening and deepening.Furthermore,coupled seepage-overtopping extends the downstream deposition area and exacerbates channel erosion due to differences in sediment sorting.These findings highlight the critical role of seepage in landslide dam breaching,providing a scientific basis for hazard prevention and mitigation. 展开更多
关键词 Seepage Non-cohesive landslide dams Particle size distribution Breaching mechanisms Dam failure
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GranuSAS:Software of rapid particle size distribution analysis from small angle scattering data 认领 引用
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作者 Qiaoyu Guo Fei Xie +3 位作者 Xuefei Feng Zhe Sun Changda Wang Xuechen Jiao 《Chinese Physics B》 SCIE EI CAS CSCD 2026年第2期216-225,共10页
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
关键词 small angle x-ray scattering data analysis software particle size distribution inverse problem
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Effects of aggregate size distribution and carbon nanotubes on the mechanical properties of cemented gangue backfill samples under true triaxial compression 认领 引用 被引量：6
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作者 Qian Yin Fan Wen +7 位作者 Zhigang Tao Hai Pu Tianci Deng Yaoyao Meng Qingbin Meng Hongwen Jing Bo Meng Jiangyu Wu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2025年第2期311-324,共14页
The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious materials.Consequently,the true triaxial compressio... The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious materials.Consequently,the true triaxial compression tests,CT scanning,SEM,and EDS tests were conducted on cemented gangue backfill samples(CGBSs)with various carbon nanotube concentrations(PCNT)that satisfied fractal theory for the PSD of aggregates.The mechanical properties,energy dissipations,and failure mechanisms of the CGBSs under true triaxial compression were systematically analyzed.The results indicate that appropriate carbon nanotubes(CNTs)effectively enhance the mechanical properties and energy dissipations of CGBSs through micropore filling and microcrack bridging,and the optimal effect appears at PCNTof 0.08wt%.Taking PSD fractal dimension(D)of 2.500 as an example,compared to that of CGBS without CNT,the peak strength(σp),axial peak strain(ε1,p),elastic strain energy(Ue),and dissipated energy(Ud)increased by 12.76%,29.60%,19.05%,and90.39%,respectively.However,excessive CNTs can reduce the mechanical properties of CGBSs due to CNT agglomeration,manifesting a decrease inρp,ε1,p,and the volumetric strain increment(Δεv)when PCNTincreases from 0.08wt%to 0.12wt%.Moreover,the addition of CNTs improved the integrity of CGBS after macroscopic failure,and crack extension in CGBSs appeared in two modes:detour and pass through the aggregates.Theσpand Udfirstly increase and then decrease with increasing D,and porosity shows the opposite trend.Theε1,pandΔεvare negatively correlated with D,and CGBS with D=2.150 has the maximum deformation parameters(ε1,p=0.05079,Δεv=0.01990)due to the frictional slip effect caused by coarse aggregates.With increasing D,the failure modes of CGBSs are sequentially manifested as oblique shear failure,"Y-shaped"shear failure,and conjugate shear failure. 展开更多
关键词 cemented gangue backfill materials particle size distribution true triaxial compression test carbon nanotubes mechanical properties failure modes
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Investigation of Summer Raindrop Size Distributions and Associated Relations in the Semi-arid Region over Inner Mongolian Plateau,China 认领 引用 被引量：1
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作者 Lina SHA Jingjing LÜ +5 位作者 Bin ZHU Chunsong LU Yue ZHOU Shengjie NIU Haixing GONG Liang SU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2025年第5期1026-1042,共17页
The characteristics of summertime raindrop size distribution(DSD) and associated relations in the semi-arid region over the Inner Mongolian Plateau(IMP) were investigated,utilizing five-year continuous observations by... The characteristics of summertime raindrop size distribution(DSD) and associated relations in the semi-arid region over the Inner Mongolian Plateau(IMP) were investigated,utilizing five-year continuous observations by a PARSIVEL2disdrometer in East Ujimqin County(EUC),China.It is found that only 7.94% of the 15 664 one-min precipitation samples meet classification criteria as convective rain(CR),but its contribution to the total rainfall amount is 63.87%.Notably,40.72% of the rainfall comes from large-sized raindrops(D> 3 mm),despite the fact that large-sized raindrops account for only 1.73% of the CR total number concentration.Further results show that the mean value of mass-weighted mean diameters(Dm) is larger(2.43 mm) and generalized intercepts(lgNW) is lower(3.19) in CR,aligning with a "continentallike" cluster,which is mainly influenced by the joint impact of in-cloud ice-based processes and the below-cloud environmental background.Also,the empirical relationships of shape-slope(μ-Λ),radar reflectivity-rain rate(Z-R),and rainfall kinetic energy(KEtime-Rand KEtime-Z) are localized.To quantitatively analyze the impact of DSD parameters on kinetic energy estimation,power-law KEtime-R and KEtime-Z relationships are derived based on the normalized gamma distribution.NWtakes precedence over μ in affecting variabilities of multiplicative coefficients,especially for KEtime-R relationship where the multiplicative coefficient is proportional to NW-0.287.It should be noted that although the proportion of CR occurring throughout the summer is small,raindrops with lower NW and larger Dmwill generate higher KEtime,which will bring a higher potential risk of soil erosion in semi-arid regions over IMP. 展开更多
关键词 semi-arid area raindrop size distribution kinetic energy cold cloud processes Inner Mongolian Plateau
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Comparison of the Grain Size Distribution Information Between Different Parallel Samples:A Case Study of the Jinsha Bay Leisure Beach,Northeastern Leizhou Peninsula 认领 引用 被引量：1
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作者 LI Gaocong YUAN Mingming +1 位作者 TANG Jieping LIAO Jian 《Journal of Ocean University of China》 SCIE CAS CSCD 2025年第3期618-630,共13页
The investigation of whether sediment samples contain representative grain size distribution information is important for the accurate extraction of sediment characteristics and conduct of related sedimentary record s... The investigation of whether sediment samples contain representative grain size distribution information is important for the accurate extraction of sediment characteristics and conduct of related sedimentary record studies.This study comparatively analyzed the numerical and qualitative differences and the degree of correlation of 36 sets of the characteristic parameters of surface sediment parallel sample grain size distribution from three sampling profiles at Jinsha Bay Beach in Zhanjiang,western Guangdong.At each sampling point,five parallel subsamples were established at intervals of 0,10,20,50,and 100 cm along the coastline.The research findings indicate the following:1)relatively large differences in the mean values of the different parallel samples(0.19–0.34Φ),with smaller differences observed in other characteristic grain sizes(D10,D50,and D90);2)small differences in characteristic values among various parallel sample grain size parameters,with at least 33%of the combinations of qualitative results showing inconsistency;3)50%of the regression equations between the skewness of different parallel samples displaying no significant correlation;4)relative deviations of−47.91%to 27.63%and−49.20%to 2.08%existing between the particle size parameters of a single sample and parallel samples(with the average obtained)at intervals of 10 and 50 cm,respectively.As such,small spatial differences,even within 100 cm,can considerably affect grain size parameters.Given the uncertain reasons underlying the representativeness of the samples,which may only cover the area immediately surrounding the sampling station,researchers are advised to design parallel sample collection strategies based on the spatiotemporal distribution characteristics of the parameters of interest during sediment sample collection.This study provides a typical case of the comparative analysis of parallel sample grain size parameters,with a focus on small spatial beach sediment,which contributes to the enhanced understanding of the accuracy and reliability of sediment sample collection strategies and extraction of grain size information. 展开更多
关键词 grain size distribution information sediment samples representativeness multiple characteristic parameters leisure beaches in western Guangdong
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Combustion aerosols and suspended dust with controlled processes in Lhasa:Elemental analysis and size distribution characteristics 认领 引用
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作者 Jinglin Li Zhuoga Deqing +3 位作者 Jie Liang Tao Guo Jian Yao Wei Liu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2025年第2期591-601,共11页
To explore air contamination resulting from special biomass combustion and suspended dust in Lhasa,the present study focused on the size distribution and chemical characteristics of particulate matter(PM)emission resu... To explore air contamination resulting from special biomass combustion and suspended dust in Lhasa,the present study focused on the size distribution and chemical characteristics of particulate matter(PM)emission resulting from 7 types of non-fossil pollution sources.We investigated the concentration and size distribution of trace elements from 7 pollution sources collected in Lhasa.Combining Lhasa’s atmospheric particulate matter data,enrichment factors(EFs)have been calculated to examine the potential impact of those pollution sources on the atmosphere quality of Lhasa.The highest mass concentration of total elements of biomass combustion appeared at PM0.4,and the second highest concentration existed in the size fraction 0.4-1μm;the higher proportion(12%)of toxicmetals was produced by biomass combustion.The elemental composition of suspended dust and atmospheric particulate matter was close(except for As and Cd);the highest concentration of elements was all noted in PM2.5-10(PM3-10).Potassium was found to be one of the main biomass markers.The proportion of Cu in suspended dust is significantly lower than that of atmospheric particulate matter(0.53%and 3.75%),which indicates that there are other anthropogenic sources.The EFs analysis showed that the Cr,Cu,Zn,and Pb produced by biomass combustion were highly enriched(EFs>100)in all particle sizes.The EFs of most trace elements increased with decreasing particle size,indicating the greater influence of humanfactors on smaller particles. 展开更多
关键词 Size distribution Trace elements Particulate matter Enrichment factors Lhasa
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Comparison of Monsoon Raindrop Size Distribution Between Inland and Coastal in South China 认领 引用
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作者 LAI Rui-ze HU Sheng +2 位作者 LIU Xian-tong XIAO Hui LI Hui-qi 《Journal of Tropical Meteorology》 SCIE CSCD 2025年第2期223-236,共14页
The raindrop size distribution(DSD) is a significant characteristic of precipitation physics,which plays a crucial role in improving the accuracy of radar quantitative precipitation estimation and prediction.There is ... The raindrop size distribution(DSD) is a significant characteristic of precipitation physics,which plays a crucial role in improving the accuracy of radar quantitative precipitation estimation and prediction.There is an effect of atmospheric circulation and weather sy stems in South China,with frequent precipitation and differences in regional features,resulting in a limited understanding of the DSD characteristics and their impact mechanisms in the region. In this study,six ground-based two-dimensional video di sdrometers(2DVDs) were used to analyze the DSD of inland and coastal in South China during the five-year(2016-2020) monsoon seasons(April to September),ERA5 reanalysis data and MODIS cloud property products were also used to investigate the dynamics and microphysical characteristics of monsoon precipitation.Compared to inland rainfall,coastal rainfall has a higher conentration of small,medium,and diameter of less than 4.7 mm large raindrops.Considering the contributions to precipitation,the inland and coastal rainfall are dominated by convective rain,accounting for 74.8% and 84.7% of the total rainfall,respectively.The coastal rainfall has a higher the mass-weiglited mean diameter(Dm) value than the inland rainfall Dm for both the stratiform and convective rainfall.The logarithmic mean of the generalized intercept parameter(log10Nw) in inland stratiform rain is greater than that in coastal areas,while convective rain is relatively small.Due to the impact of precipitation types and climate conditions,The Z-R relationship between inland and coastal rainfall also shows obvious differences.Compared to inland areas,there is more frequent convective activity,relatively moist near-surface conditions,and lower cloud droplet number concentrations,which contribute to larger Dm of raindrops in coastal areas.This study deepens the understanding of changes in South China's coastal and inland DSD and provides support for improving numerical weather forecasting in the region. 展开更多
关键词 raindrop size distribution monsoon rainfall regional variability South China
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Impacts of observation-based cloud droplet size distributions on the simulation of warm stratiform precipitation using a double-moment microphysics scheme 认领 引用
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作者 Ryohei Misumi Akihiro Hashimoto 《Atmospheric and Oceanic Science Letters》 CSCD 2025年第5期1-7,共7页
A double-moment cloud microphysics scheme requires an assumption for cloud droplet size distributions(DSDs).However,since observations of cloud DSDs are limited,default values for shape parameters and cloud condensati... A double-moment cloud microphysics scheme requires an assumption for cloud droplet size distributions(DSDs).However,since observations of cloud DSDs are limited,default values for shape parameters and cloud condensation nuclei activation parameters are often used in numerical simulations.In this study,the effects of cloud DSDs on numerical simulations of warm stratiform precipitation around Tokyo are investigated using the Japan Meteorological Agency's non-hydrostatic model,which incorporates a double-moment cloud microphysics scheme.Simulations using the default cloud DSD showed higher cloud droplet number concentrations and lower radar reflectivity than observed data,suggesting that the default cloud DSD is too narrow.Simulations with a cloud DSD based on in situ cloud observations corrected these errors.In addition,observation-based cloud DSDs affected rainfall amounts through the autoconversion rate of cloud water and improved the threat scores.These results suggest that realistic cloud DSDs should be provided for double-moment cloud microphysics schemes in scientific studies. 展开更多
关键词 Cloud microphysics Cloud droplet size distribution Autoconversion
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Effects of Dynamics Behavior and Size Distribution of Supercooled Large Droplets on Ice Accretion Processes 认领 引用
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作者 ZHANG Dexin ZENG Tenghui +5 位作者 WANG Liu SUN Bo CHENG Zikang FENG Jiaxin XIE Junlong CHEN Jianye 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2025年第2期201-211,共11页
Accurate simulation of ice accretion of supercooled large droplet(SLD)is pivotal for the international airworthiness certification of large aircraft.Its complex dynamics behavior and broad particle size distributions ... Accurate simulation of ice accretion of supercooled large droplet(SLD)is pivotal for the international airworthiness certification of large aircraft.Its complex dynamics behavior and broad particle size distributions pose significant challenges to reliable CFD predictions.A numerical model of multi-particle SLD coupling breaking,bouncing and splashing behaviors is established to explore the relationship between dynamics behavior and particle size.The results show that the peak value of droplet collection efficiencyβdecreases due to splashing.The bounce phenomenon will make the impact limit Smof the water drops decrease.With the increase of the SLD particle size,the water drop bounce point gradually moves toward the trailing edge of the wing.The critical breaking diameter of SLD at an airflow velocity of 50 m/s is approximately 100μm.When the SLD particle size increases,the height of the water droplet shelter zone on the upper edge of the wing gradually decreases,and the velocity in the Y direction decreases first and then increases in the opposite direction,increasing the probability of SLD hitting the wing again.Large particle droplets have a higher effect on the impact limit Smthan smaller droplets.Therefore,in the numerical simulation of the SLD operating conditions,it is very important to ensure the proportion of large particle size water droplets. 展开更多
关键词 supercooled large droplet(SLD) splash and bounce break up effect critical diameter particle size distribution
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Influence of particle size distribution and normal pressure on railway ballast:A DEM approach 认领 引用
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作者 Z.Yan Ali Zaoui W.Sekkal 《High-Speed Railway》 CSCD 2025年第1期28-36,共9页
Developing the railway transport sector is a challenging scientific,economic and social research topic starting with ensuring human security.The main topic that should be developed in that sense is the ballast stabili... Developing the railway transport sector is a challenging scientific,economic and social research topic starting with ensuring human security.The main topic that should be developed in that sense is the ballast stability and dynamical behaviour under external loading and environmental changes.This paper investigates the effect of particle size distribution and normal pressure on the mechanical response of a ballast bed.Grading curves of ballast layers with different sizes are illustrated to discuss their strength behaviour under various strains to deduce the significant effect on the direct shear performance of the ballast layer.Direct shear tests with different Particle Size Distribution(PSD)were reproduced using the Discrete Element Method(DEM).It is noticed that when the number of small-sized ballast increases,the shear strength and the friction angle increase to varying degrees under different normal pressures,with an average increase of 27%and 8%,respectively.When the number of large-sized ballast decreases,the shear strength and the friction angle decrease to varying degrees under different normal pressures,with an average decrease of 6%and 3%,respectively. 展开更多
关键词 DEM Ballast Direct shear test Particle size distribution
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Mechanical properties of Mg-8Gd-3Y-0.5Zr alloy with bimodal grain size distributions 认领 引用 被引量：34
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作者 J.H.He L.Jin +2 位作者 F.H.Wang S.Dong J.Dong 《Journal of Magnesium and Alloys》 SCIE CAS 2017年第4期423-429,共7页
The Mg-Gd-Y-Zn-Zr alloys are representational and potential age-hardening systems as reported in the past ten years,but their mechanical properties are still dependent on the grain size and its distribution.The effect... The Mg-Gd-Y-Zn-Zr alloys are representational and potential age-hardening systems as reported in the past ten years,but their mechanical properties are still dependent on the grain size and its distribution.The effect of bimodal structure on mechanical properties of Mg-8Gd-3Y-0.5Zr alloy with bimodal grain size distributions was investigated.The results suggested that the volume fraction of fine grain(FG)and coarse grain(CG)could be controlled by combined processes of hot forging,extrusion and annealing.And for the present alloys with bimodal grain size distribution,the improvement of strength is still attributed to the grain refinement.The morphology of bimodal grain size distribution has a marked impact on the ductility of the alloy,i.e.with the increase of coarse grain volume fraction,the elongation to failure increases at the beginning and then decreases.The mechanism of the toughening effect of bimodal grain size distribution on the Mg-Gd-Y-Zn-Zr alloys with bimodal grain size structure has been discussed. 展开更多
关键词 Mg-Gd-Y-Zr alloy Forging Extrusion Bimodal grain size distribution Mechanical properties
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Number concentration and size distributions of submicron particles in Jinan urban area:Characteristics in summer and winter 认领 引用 被引量：22
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作者 GAO Jian WANG Jin +5 位作者 CHENG Shu-hui XUE Li-kun YAN Huai-zhong HOU Lu-jian JIANG Yu-quan WANG Wen-xing 《Journal of Environmental Sciences》 SCIE EI CAS 2007年第12期1466-1473,共8页
The aerosol number concentration and size distribution were measured with the newly developed Wide-range Particle Spectrometer in summer and winter of 2006 at the urban site of Jinan City. Here reported the characteri... The aerosol number concentration and size distribution were measured with the newly developed Wide-range Particle Spectrometer in summer and winter of 2006 at the urban site of Jinan City. Here reported the characteristics of fine particles of the different observation seasons. Relative high number concentrations for the particles in the diameter range of 10-500 nm were observed in both seasons. It was found that the dominant number distributed in particle diameter smaller than 100 nm and the percentage over the number concentration of all air particles is much higher than what has been measured in other urban sites over the world. The number mean diameter in summer was much smaller than in winter, strongly suggesting the different origin of ultrafine particles in different seasons. That is, particles in ultrafine mode mainly came from nucleation and new particle formation in summer while from traffic emission in winter. The diurnal variation also supported this point. Number concentration in the diameter range of 10-200 um got their peak values at noontime, well correlated with the mixing ratio of SO2 and the intensity of solar radiation in summer. While in winter, those in the same diameter range showed the main peaks during the traffic hours happened in the morning and evening. 展开更多
关键词 number concentration size distribution seasonal variation diurnal variation
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Size distribution and diffuse pollution impacts of PAHs in street dust in urban streams in the Yangtze River Delta 认领 引用 被引量：18
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作者 ZHAO Hongtao YIN Chengqing +3 位作者 CHEN Meixue WANG Weidong Jefferies Chris SHAN Baoqing 《Journal of Environmental Sciences》 SCIE EI CAS 2009年第2期162-167,共6页
Particles of dust washed off streets by stormwater are an important pathway of polyaromatic hydrocarbons （PAHs） into urban streams. This article presented a comprehensive assessment of the size distribution of PAHs ... Particles of dust washed off streets by stormwater are an important pathway of polyaromatic hydrocarbons （PAHs） into urban streams. This article presented a comprehensive assessment of the size distribution of PAHs in street dust particles, the potential risks of the particles in urban streams, and the sources and sinks of PAHs in the stream network. This assessment was based on measurements of 16 PAHs from the USEPA priority list in street dust particles and river sediments in Xincheng, China. The content of total PAHs ranged from 1629 to 8986 Dg/kg in street dust particles, where smaller particles have a higher concentrations. Approximately 55% of the total PAHs were associated with particles less than 250 μm which accounted for 40% of the total mass of street dust. The PAH quantities increased from 2.41 to 46.86 μg/m2 in the sequence of new residential, rising through main roads, old town residential, commercial and industrial areas. The sediments in stream reaches in town were found to be sinks for street dust particle PAHs. The research findings suggested that particle size, land use and the hydrological conditions in the stream network were the factors which most influenced the total loads of PAH in the receiving water bodies. 展开更多
关键词 PAHs street dust particle size distribution land use pollutant load
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Particle number size distribution and new particle formation:New characteristics during the special pollution control period in Beijing 认领 引用 被引量：16
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作者 Jian Gao Fahe Chai +2 位作者 Tao Wang Shulan Wang Wenxing Wang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2012年第1期14-21,共8页
New particle formation is a key process in shaping the size distribution of aerosols in the atmosphere.We present here the measurement results of number and size distribution of aerosol particles （10–10000 nm in dia... New particle formation is a key process in shaping the size distribution of aerosols in the atmosphere.We present here the measurement results of number and size distribution of aerosol particles （10–10000 nm in diameter） obtained in the summer of 2008,at a suburban site in Beijing,China.We firstly reported the pollution level,particle number size distribution,diurnal variation of the particle number size distribution and then introduced the characteristics of the particle formation processes.The results showed that the number concentration of ultrafine particles was much lower than the values measured in other urban or suburban areas in previous studies.Sharp increases of ultrafine particle count were frequently observed at noon.An examination of the diurnal pattern suggested that the burst of ultrafine particles was mainly due to new particle formation promoted by photochemical processes.In addition,high relative humidity was a key factor driving the growth of the particles in the afternoon.During the 2-month observations,new particle formation from homogeneous nucleation was observed for 42.7% of the study period.The average growth rate of newly formed particles was 3.2 nm/hr,and varied from 1.2 to 8.0 nm/hr.The required concentration of condensable vapor was 4.4×10 7 cm-3,and its source rate was 1.2×10 6 cm-3 sec-1.Further calculation on the source rate of sulphuric acid vapor indicated that the average participation of sulphuric acid to particle growth rates was 28.7%. 展开更多
关键词 Beijing particle number size distribution new particle formation condensational sink sulphuric acid
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Size distributions of aerosol and water-soluble ions in Nanjing during a crop residual burning event 认领 引用 被引量：19
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作者 Honglei Wang Bin Zhu +1 位作者 Lijuan Shen Hanqing Kang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2012年第8期1457-1465,共9页
To investigate the impact on urban air pollution by crop residual burning outside Nanjing, aerosol concentration, pollution gas concentration, mass concentration, and water-soluble ion size distribution were observed ... To investigate the impact on urban air pollution by crop residual burning outside Nanjing, aerosol concentration, pollution gas concentration, mass concentration, and water-soluble ion size distribution were observed during one event of November 4-9, 2010. Results show that the size distribution of aerosol concentration is bimodal on pollution days and normal days, with peak values at 60- 70 and 200-300 nm, respectively. Aerosol concentration is 104 cm-3.nm-1 on pollution days. The peak value of spectrum distribution of aerosol concentration on pollution days is 1.5-3.3 times higher than that on a normal day. Crop residual burning has a great impact on the concentration of fine particles. Diurnal variation of aerosol concentration is trimodal on pollution days and normal days, with peak values at 03：00, 09：00 and 19：00 local standard time. The first peak is impacted by meteorological elements, while the second and third peaks are due to human activities, such as rush hour traffic. Crop residual burning has the greatest impact on SO2 concentration, followed by NO2, 03 is hardly affected. The impact of crop residual burning on fine particles （〈 2.1 μm） is larger than on coarse particles （〉 2.1 μm）, thus ion concentration in fine particles is higher than that in coarse particles. Crop residual burning leads to similar increase in all ion components, thus it has a small impact on the water-soluble ions order. Crop residual burning has a strong impact on the size distribution of K^＋, Cl^-, Na^＋, and F- and has a weak impact on the size distributions of NH4^＋, Ca^2＋, NO3^- and SO4^2-. 展开更多
关键词 crop residual burning atmospheric aerosol number concentration mass concentration water-soluble ions size distribution
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Size distribution and source of heavy metals in particulate matter on the lead and zinc smelting affected area 认领 引用 被引量：14
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作者 Kai Zhang Fahe Chai +4 位作者 Zilong Zheng Qing Yang Xuecai Zhong Khanneh Wadinga Fomba Guangzhu Zhou 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2018年第9期188-196,共9页
In order to understand the size distribution and the main kind of heavy metals in particulate matter on the lead and zinc smelting affected area, particulate matter （PM） and the source samples were collected in Zhuz... In order to understand the size distribution and the main kind of heavy metals in particulate matter on the lead and zinc smelting affected area, particulate matter （PM） and the source samples were collected in Zhuzhou, Hunan Province from December 2011 to January 2012 and the results were discussed and interpreted. Atmospheric particles were collected with different sizes by a cascade impactor. The concentrations of heavy metals in atmospheric particles of different sizes, collected from the air and from factories, were measured using an inductively coupled plasma mass spectrometry （ICP-MS）. The results indicated that the average concentration of PM, chromium （Cr）, arsenic （As）, cadmium （Cd） and lead （Pb） in PM was 177.3 ± 33.2 μg/m^3, 37.3 ± 8.8 ng/m^3, 17.3 ± 8.1 ng/m^3, 4.8 ± 3.1 ng/m^3 and 141.6 ± 49.1 ng/m^3, respectively. The size distribution of PM displayed a bimodal distribution; the maximum PM size distribution was at 1.1-2.1 μm, followed by 9-10 μm. The size distribution of As, cd and Pb in PM was similar to the distribution of the PM mass, with peaks observed at the range of 1.1-2.1 μm and 9-10 μm ranges while for Cr, only a single-mode at 4.7-5.8 μm was observed. PM （64.7%, As （72.5%）, cd （72.2%） and Pb （75.8%） were associated with the fine mode below 2.1 μm, respectively, while Cr （46.6%） was associated with the coarse mode. The size distribution characteristics, enrichment factor, correlation coefficient values, source information and the analysis of source samples showed that As, Cd and Pb in PM were the typical heavy metal in lead and zinc smelting affected areas, which originated mainly from lead and zinc smelting sources. 展开更多
关键词 Atmospheric particulate matter Size distribution Heavy metals Pollution characteristics Lead and zinc smelting
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Comparative Analysis of the Characteristics of Rainy Season Raindrop Size Distributions in Two Typical Regions of the Tibetan Plateau 认领 引用 被引量：10
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作者 Gaili WANG Ran LI +3 位作者 Jisong SUN Xiangde XU Renran ZHOU Liping LIU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2022年第7期1062-1078,共17页
Mêdog and Nagqu are two typical regions of the Tibetan Plateau with different geographical locations and climate regimes.These differences may lead to discrepancies in the raindrop size distributions(DSDs)and pre... Mêdog and Nagqu are two typical regions of the Tibetan Plateau with different geographical locations and climate regimes.These differences may lead to discrepancies in the raindrop size distributions(DSDs)and precipitation microphysical processes between the two regions.This paper investigates discrepancies in the DSDs using disdrometer data obtained during the rainy season in Mêdog and Nagqu.The DSD characteristics are studied under five different rainfall rate categories and two precipitation types(stratiform and convective).For the total datasets,the number concentrations of drops with diameters D>0.6(D<0.6)mm are higher(lower)in Nagqu than in Mêdog.The fitted normalized gamma distributions of the averaged DSDs for the five rainfall rate categories show that Nagqu has a larger(lower)mass-weighted mean diameter Dm(normalized intercept parameter,lgNw)than Mêdog does.The difference in Dmbetween Nagqu and Mêdog increases with the rainfall rate.Convective clusters in Nagqu could be identified as continental-like,while convective precipitation in Mêdog could be classified as maritime-like.The relationships between the shape factorμand slope parameterΛof the gamma distribution model,the radar reflectivity Z,and the rainfall rate R are also derived.Furthermore,the possible causative mechanism for the notable DSD variation between the two regions during the rainy season is illustrated using reanalysis data and automated weather station observations.Cold rain processes are mainly responsible for the lower concentrations of larger drops observed in Nagqu,whereas warm rain prevails in Mêdog,producing abundant small drops. 展开更多
关键词 raindrop size distribution Tibetan Plateau continental-like maritime-like warm rain cold rain
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