Mass wasting is globally recognized as a key geomorphic agent in permanent gully expansion and greatly contributes to watershed sediment losses.Though its formation process has been assessed by some physical models,th...Mass wasting is globally recognized as a key geomorphic agent in permanent gully expansion and greatly contributes to watershed sediment losses.Though its formation process has been assessed by some physical models,the occurrence and rainfall threshold have been rarely documented.In this study,rainfall-induced mass wasting events in two permanent gullies located in the Mollisols region of Northeast China,with Mollisols(gully 1)and sandy soil(gully 2)underneath were observed,and their differences were explored based on their soil strengths,hydraulic properties,excess topographies,and theoretical rainfall amounts.The sandy soil had a higher strength,faster pore water pressure dissipation rate,and lower suction stress at a specific soil moisture content compared to the black soil.The erosion thickness of the gully bed and sidewalls in gully 1 was shallower compared to gully 2.This was confirmed by the relationship between the erosion thickness and excess topography.The differences in the mass wasting erosion of the gully bed and sidewalls were due to the higher shear strength and well-drained hydraulic properties of the sandy soil compared to the black-soil.An infinite model was chosen to examine the temporal order of the mass wasting in the two gullies.It was found that the mass wasting in gully 2 occurred earlier than that in gully 1.This was likely due to the occurrence of an intense storm with less rainfall at the location of gully 2,while a light storm with heavier rainfall occurred in the location of gully 1.As Mollisols and sandy soil are the typical soil horizons in the Mollisols region worldwide,the results of this work could provide insightful knowledge for understanding the physical process of permanent gully expansion,which may be helpful for developing prediction models for sediment losses in some watersheds with vast Mollisols and highly developed gully system.展开更多
As the main component of the aircraft leading edge,the radome is often the first to be hit by raindrops and cause structural damage when passing through a rain field.Rain resistant coating is usually applied to ensure...As the main component of the aircraft leading edge,the radome is often the first to be hit by raindrops and cause structural damage when passing through a rain field.Rain resistant coating is usually applied to ensure the performance protection requirements.In order to clarify the rain erosion damage mechanism of radome coating and explore the influencing factors and mechanisms of coating material damage under different jet impact conditions,impact tests were conducted on three types of skin coating samples,and the damage mode was observed through electron microscopy characterization.The experimental results show that the typical morphology of rain erosion damage is annular surface peeling damage.The damage area and volume of the three coating samples increase with the continuous increase of raindrop impact velocity.The threshold velocity for initial damage to the coating is about 360 m/s;under the influence of the velocity component,the reduction in impact angle leads to a gradual reduction in the degree of damage to the sample.ABAQUS finite element simulation software was used to establish a constitutive model for coating rain erosion simulation and obtain the propagation law of stress waves during the impact process.The simulation results show that at the 75°impact angle,the jet impacts the surface of the specimen at different velocities,and as the impact velocity increases,the Mises equivalent stress on the surface shows an increasing trend,which is one of the main factors causing damage with increasing velocity.The effectiveness,rain erosion damage mode,and influencing mechanism of the model were verified based on the test results;the dynamic failure mechanism of the sample was further studied,and the stress propagation process at different impact angles was compared,revealing the influence mechanism and damage law of the impact angle on the high-speed raindrop impact of the material.展开更多
Glacier landslide cascading hazards pose threats to communities and infrastructure,affected by complex processes including the amplification of mass flow volume through erosion and entrainment,transformation of hazard...Glacier landslide cascading hazards pose threats to communities and infrastructure,affected by complex processes including the amplification of mass flow volume through erosion and entrainment,transformation of hazard types,ice-water phase change,and enhanced mobility of the mass flow.Scientifically simulating these physical phenomena proves challenging.This study introduces GMFA(glacier mass flow analysis),an integrated numerical model that advances the field by:(1)proposing depth-averaged fluctuation energy and internal energy equations,(2)incorporating the ice-water phase change and the entrainment-deposition process,and(3)capturing their effects on mass flow runout characteristics.The model employs the finite volume method to solve the multi-physics coupled governing equations,enabling efficient large-scale simulations.The model is verified through three numerical tests covering flow dynamics,temperature evolution,and thermo-hydro-mechanical runout processes.The model is applied to analyze a hazard chain that occurred on 10 September 2020 on the Tibetan Plateau.The multi-scenario simulation results indicate an entrained mass volume of(4.95±0.11)×10^(5)m^(3),and a ratio of entrained mass volume to source material volume of 0.44.The solid concentration decreases from 0.6-0.7 to 0.1-0.15 with increasing runout distance,indicating a transition from avalanche to debris flood.The internal energy rises by(3-4)×10^(3)kJ/m^(3),driving rapid ice melting from 0.1 to 0.2 to near-zero concentration.The model effectively quantifies volume amplification,ice-water phase changes,and multi-hazard transformations.This model pushes the geoscience frontier,extending computational capability from single-to multi-hazard simulations and providing a powerful tool for analyzing glacier cascading hazards.展开更多
During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this...During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this paper,the electrochemical dissolution behavior of Ti-6.5Al-2Zr-1Mo-1V(TA15)titanium alloy at without particle impact,low(15°)and high(90°)angle particle impact was investigated,and the influence of Al_(2)O_(3)particles on ECM was systematically expounded.It was found that under the condition of no particle erosion,the surface of electrochemically processed titanium alloy had serious pitting corrosion due to the influence of the passivation film,and the surface roughness(Sa)of the local area reached 10.088μm.Under the condition of a high-impact angle(90°),due to the existence of strain hardening and particle embedding,only the edge of the surface is dissolved,while the central area is almost insoluble,with the surface roughness(S_(a))reaching 16.086μm.On the contrary,under the condition of a low-impact angle(15°),the machining efficiency and surface quality of the material were significantly improved due to the ploughing effect and galvanic corrosion,and the surface roughness(S_(a))reached 2.823μm.Based on these findings,the electrochemical dissolution model of TA15 titanium alloy under different particle erosion conditions was established.展开更多
Freeze-thaw cycles(FTCs)have an important effect on soil aggregate stability by altering soil structures,thereby influencing soil wind and water erosion on the eastern Qinghai-Tibet Plateau.However,the effects of FTCs...Freeze-thaw cycles(FTCs)have an important effect on soil aggregate stability by altering soil structures,thereby influencing soil wind and water erosion on the eastern Qinghai-Tibet Plateau.However,the effects of FTCs on the stability of these soils remain unclear.Here,we conducted freeze-thaw simulations in laboratory to investigate the effects of FTCs(0 to 15 cycles)on the wet-and dry-sieving aggregate stability of undisturbed sandy loam from Maqu county,which was treated with different initial soil moisture contents(1%to 25%in increments of 4%)and initial aggregate diameters(<2,2-5,5-10,and 10-15 mm).Results show that soil aggregates with initial diameters larger than 2 mm exhibit higher soil organic carbon contents(1.45%-1.57%)and silt contents(34.63%-35.52%)than those smaller than 2 mm(0.93%and 31.38%,respectively).The stability of both wet-and dry-sieving aggregates increases with larger initial diameters.Increasing initial soil moisture content from 1%to 25%reduces aggregate stability,with reductions of 2.4%-88.0%for wet-sieving aggregates and 2.1%-25.5%for dry-sieving aggregates(>2 mm).With increasing FTCs,wet-sieving aggregate(>2 mm)stability exhibits a fluctuating upward trend,with increases of 79.2%-87.4%after 15 FTCs,while dry-sieving aggregate(>2 mm)stability decreases significantly(5.7%-21.7%)upon the first FTC and remains unchanged thereafter.The stability of both the wet-and dry-sieving aggregates smaller than 2 mm remains unchanged with increasing FTCs(p>0.05).SOC content decreases by 22.3%on average with increasing FTCs from 1 to 15 and shows no significant correlations with wet-and dry-sieving aggregate stability.Higher silt content(r=0.39,p<0.05)and lower sand content(r=-0.38,p<0.05)enhances the wet-sieving aggregate stability of sandy loam.Frequent FTCs tend to improve wet-sieving aggregate stability but reduce dry-sieving aggregate stability in the sandy loam.The findings provide certain guidance for preventing freeze-thaw-induced wind erosion.展开更多
To resolve severe slag penetration and erosion in Al_(2)O_(3)-SiC-C refractories during high scrap ratio iron ladle operation,a novel strategy utilizing exogenous MgAl_(2)O_(4) spinel as a sacrificial FeO_(x) scavenge...To resolve severe slag penetration and erosion in Al_(2)O_(3)-SiC-C refractories during high scrap ratio iron ladle operation,a novel strategy utilizing exogenous MgAl_(2)O_(4) spinel as a sacrificial FeO_(x) scavenger was proposed.Al_(2)O_(3)-SiC-C refractories produced with plate-like corundum,silicon carbide,and flake graphite incorporating MgAl_(2)O_(4) additives were cured at 1400℃ in the condition of carbon embedding.The impacts of additives on phase composition,microscopic morphology,and performance of materials were studied.The results indicated that Al_(2)O_(3)-SiC-C refractories with the addition of 2 wt.%MgAl_(2)O_(4) exhibited a smaller oxidation area after oxidation tests compared to samples without MgAl_(2)O_(4),resulting in 28%improvement in oxidation resistance compared to blank samples.In the erosion test,the results informed that adding 4 wt.%MgAl_(2)O_(4) induced significant interfacial slag modification:MgAl_(2)O_(4) dynamically dissolved FeO_(x) to form protective Mg(Fe,Al)_(2)O_(4) solid solution on the slag-refractory interface.This sacrificial dissolution effectively immobilized FeO_(x),elevated local slag viscosity,and fundamentally inhibited slag penetration and matrix dissolution.The erosion index decreased from 50%in the blank group to 27.4%.展开更多
Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing...Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.展开更多
Wildfires significantly disrupt the physical and hydrologic conditions of the environment,leading to vegetation loss and altered surface geo-material properties.These complex dynamics promote post-fire gully erosion,y...Wildfires significantly disrupt the physical and hydrologic conditions of the environment,leading to vegetation loss and altered surface geo-material properties.These complex dynamics promote post-fire gully erosion,yet the key conditioning factors(e.g.,topography,hydrology)remain insufficiently understood.This study proposes a novel artificial intelligence(AI)framework that integrates four machine learning(ML)models with Shapley Additive Explanations(SHAP)method,offering a hierarchical perspective from global to local on the dominant factors controlling gully distribution in wildfireaffected areas.In a case study of Xiangjiao catchment burned on March 28,2020,in Muli County in Sichuan Province of Southwest China,we derived 21 geoenvironmental factors to assess the susceptibility of post-fire gully erosion using logistic regression(LR),support vector machine(SVM),random forest(RF),and convolutional neural network(CNN)models.SHAP-based model interpretation revealed eight key conditioning factors:topographic position index(TPI),topographic wetness index(TWI),distance to stream,mean annual precipitation,differenced normalized burn ratio(d NBR),land use/cover,soil type,and distance to road.Comparative model evaluation demonstrated that reduced-variable models incorporating these dominant factors achieved accuracy comparable to that of the initial-variable models,with AUC values exceeding 0.868 across all ML algorithms.These findings provide critical insights into gully erosion behavior in wildfire-affected areas,supporting the decision-making process behind environmental management and hazard mitigation.展开更多
A carcass is the innermost layer of a deep-sea unbonded flexible pipe,which is in direct contact with the gas/liquid-solid multi-phase flow.Considering that stress-accelerated erosion is common for carcasses,this stud...A carcass is the innermost layer of a deep-sea unbonded flexible pipe,which is in direct contact with the gas/liquid-solid multi-phase flow.Considering that stress-accelerated erosion is common for carcasses,this study proposes a general model and simulation method for stress-accelerated erosion(SE)of carcasses under external water pressure.First,an SE model suitable for 316 stainless steel was developed,which was then used for stress-erosion simulation for an external pressurized carcass,and the solid domain,fluid domain and rough inner surface of the carcass were carefully considered.Moreover,a simplified model(equivalent smooth pipe)was also established on the basis of the main geometric characteristics of the carcass,and the stress-erosion characteristics under different operating conditions,including the effects of the elastic stress level,flow velocity,particle diameter and concentration,were carefully compared,and the key factors governing the elastic stress-erosion of the carcass were discussed.Finally,a modified geometry factor(GF)for carcasses was proposed considering the stress acceleration effect.展开更多
Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety a...Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.展开更多
To address the challenges posed by tunnel construction in the alpine region,silica fume mixed concrete is commonly used as a construction material.The correlation between silica fume content and the lining life requir...To address the challenges posed by tunnel construction in the alpine region,silica fume mixed concrete is commonly used as a construction material.The correlation between silica fume content and the lining life requires immediate investigation.In view of this phenomenon,the durability of unit lining concrete is predicted by analyzing three key indicators:carbonation depth,relative dynamic elastic modulus,and residual quality.This prediction is achieved by integrating the Entropy Weight Method,Grey theory life prediction model and BP artificial neural networks using data from tests and predictions of these indicators.Then,the Entropy Weight-Grey theory-BP Network Model is compared with other methods to analyze the predicted life.Finally,verify the sci-entificity of this model,and the optimum silica fume content of unit concrete lining is verified.The results showed,1)The addition of silica fume will accelerate the carbonization of unit concrete lining,and slow down the freeze-thaw cycle and sulfate erosion.2)The utilization of artificial neural networks is essential for enhancing the realism of the data,as it emphasizes the significance of silica fume content.3)Silica fume content of 10%results in the longest life and is the most suitable for lining construction.4)A comparison between single-factor and multi-factor predictions indicates that the multi-factor approach yields a longer maximum life.This improvement can be attributed to the inclusion of additional factors,such as freeze-thaw cycles and carbonation,which enhance the predicted life when employing these methods.In conclusion,the Entropy Weight-Grey Theory-BP Network life prediction Model is well-suited for tunnel lining in the alpine sulfate area of northwest China.展开更多
The study aims to investigate the carbonated water erosion mechanism of lining concrete in tunnels traversing karst environment and enhance its resistance.In this study,dynamic carbonated water erosion was simulated t...The study aims to investigate the carbonated water erosion mechanism of lining concrete in tunnels traversing karst environment and enhance its resistance.In this study,dynamic carbonated water erosion was simulated to assess erosion depth,microstructure,phase migrations,and pore structure in various tunnel lining cement-based materials.Additionally,Ca^(2+)leaching was analyzed,and impact of Ca/Si molar ratio in hydration products on erosion resistance was discussed by thermodynamic calculations.The results indicate that carbonated water erosion caused rough and porous surface on specimens,with reduced portlandite and CaCO_(3) content,increased porosity,and an enlargement of pore size.The thermodynamic calculations indicate that the erosion is spontaneous,driven by physical dissolution and chemical reactions dominated by Gibbs free energy.And the erosion reactions proceed more spontaneously and extensively when Ca/Si molar ratio in hydration products was higher.Therefore,cement-based materials with higher portlandite content exhibit weaker erosion resistance.Model-building concrete,with C-S-H gel and portlandite as primary hydration products,has greater erosion susceptibility than shotcrete with ettringite as main hydration product.Moreover,adding silicon-rich mineral admixtures can enhance the erosion resistance.This research offers theory and tech insights to boost cement-based material resistance against carbonated water erosion in karst tunnel engineering.展开更多
This article focuses on the clinical efficacy and mechanism of action of heatclearing and detoxifying traditional Chinese medicines(TCMs)in the treatment of erosive gastritis,providing a reference for the treatment of...This article focuses on the clinical efficacy and mechanism of action of heatclearing and detoxifying traditional Chinese medicines(TCMs)in the treatment of erosive gastritis,providing a reference for the treatment of this disease.In the clinical treatment of erosive gastritis,TCM combinations such as Qing Gastric San,Semixia Diarrheal Heart Soup,and single-flavored heat-clearing and detoxifying drugs such as dandelion and Huanglian have specific efficacies and effectively improve the patient's symptoms,including killing or inhibiting Helicobacter pylori,reducing inflammatory reactions,protecting the gastric mucosa,inhibiting gastric acid secretion,regulating gastrointestinal hormones,and regulating immune function,playing therapeutic roles through multi-level and multi-target mechanisms.Thus,heat-clearing and detoxifying TCMs have broad application prospects in clinical practice for erosive gastritis.展开更多
To verify the wear resistance and erosion resistance of Ti-doped Ta_(2)O_(5)coating(TTO),a series of TTOs were prepared by magnetron sputtering technology by controlling the power of the Ti target.The change of growth...To verify the wear resistance and erosion resistance of Ti-doped Ta_(2)O_(5)coating(TTO),a series of TTOs were prepared by magnetron sputtering technology by controlling the power of the Ti target.The change of growth structure,microstructure,and tribological properties of TTOs with Ti target power was studied.After the erosion test,the variation of erosion damage behavior of TTOs with mechanical properties under different erosion conditions was further studied.The results show that the TTOs eliminate the roughness,voids,and defects in the material due to the mobility of the adsorbed atoms during the growth process,and a flat and dense smooth surface is obtained.Tribological tests show that the TTOs are mainly characterized by plastic deformation and microcrack wear mechanism.Higher Ti target power can improve the wear resistance of TTOs.Erosion test results reveal that the impact crater,furrow,micro-cutting,brittle spalling,and crack formation are the main wear mechanisms of the TTOs samples under erosion conditions.展开更多
Soil erosion is the primary factor causing the loss of soil resources and land degradation.Clarifying the current status of soil erosion in China and the characteristics of future changes under different pathways of d...Soil erosion is the primary factor causing the loss of soil resources and land degradation.Clarifying the current status of soil erosion in China and the characteristics of future changes under different pathways of development is important to the global management of soil resources,food security,and ecosystem services.We used the revised universal soil loss equation and the most recent and reliable soil and environmental data to characterize soil erosion in China at present and under typical Shared Socioeconomic Pathways and Representative Concentration Pathways(i.e.,SSP1–2.6 and SSP5–8.5)in the medium-and long-term future(2050 and 2100).The current average rate of soil erosion in China was 14.78 t ha^(-1)yr^(-1),with a total amount of about 14.0 Pg yr^(-1).The amount of total erosion increased by 5.0%,10.8%,9.9%,and 25.9%for scenarios 2050_SSP1–2.6,2050_SSP5–8.5,2100_SSP1–2.6,and 2100_SSP5–8.5,respectively,compared to the baseline amount in 2010.The contribution of climate change and land use to the increase in erosion ranged from 9.5%to 31.5%and-6.95%to-1.78%,respectively,with the contribution of climate change about 2.36-to 7.54-fold larger than the contribution of land use.Converting arable barren land into forest and grassland or adopting conservation tillage practices for farmland,could nevertheless effectively offset the increase in erosion under the four future scenarios.This study provides data and a scientific basis for managing soil erosion in China and provides a useful reference for conserving global land resources and formulating policies to cope with climatic and environmental changes.展开更多
The increased erosion of mangrove forests has alarmed the government about the damage to both the economy and livelihoods.To evaluated forest and land erosion the coast.Based on survey data is divided into five levels...The increased erosion of mangrove forests has alarmed the government about the damage to both the economy and livelihoods.To evaluated forest and land erosion the coast.Based on survey data is divided into five levels(F1:no erosion;F2:little erosion;F3:moderate erosion;F4:high erosion;F5:strong erosion),and ecological conditions,the coast is divided into sub-regions for investigation.From the surveyed indicators at each erosion level,forest structure is analyzed for comparison.The erosion level is defined as an erosion function(Er)from 1 to 5(+),where(1)parameters include the number of trees per hectare(Ntr/ha),height to top(Ht),trunk diameter at 1.3 m(D1.3),tree canopy diameter(Dc),and width of the forest range(Wf);(2)land erosion is a function(Erl=Erlte+Erlsa+Erlsi+Erlcl),with parameters including erosion by terrain(Erlte),sand(Erlsa),silt(Erlsi),and clay(Erlcl);and(3)climate change leading to erosion is an inverse function(Cl)from 1 to 5(-),with parameters including erosion by rainfall(Clra),wind(Clwi),waves(Clwa),and tide(Clti).The resulting function output is Er=(Erf+Erl)-Cl.On eroded forest land,species were tested under climate change conditions and their growth in the next rainy season to assess survival rates affected by rainfall,waves,wind,and tides.These results help to plan planting mangrove forest anti-erosion models and construct a theoretical function of mangrove erosion and proposes restore forests using pioneer species.展开更多
Vegetation plays a major role in soil protection against erosion effects,and studies have also highlighted its importance in retaining sediments from roadside slopes.Yet,hydro-sedimentological studies under natural pr...Vegetation plays a major role in soil protection against erosion effects,and studies have also highlighted its importance in retaining sediments from roadside slopes.Yet,hydro-sedimentological studies under natural precipitation conditions are still scarce in semi-arid areas due to difficulties in monitoring the few and very concentrated precipitation events.Quantifying sediment connectivity and yield at watershed scale,often highly impacted by the erosion of unpaved roads,is necessary for management plans.This study aims to evaluate the efficiency of native vegetation on roadside slope segments in Caatinga biome in retaining sediments and conserving the soil in a semi-arid area of Brazil.Surface runoff,sediment concentration,and yield measurements were measured from 34 natural precipitation events in four years on two slopes with and without vegetation.The runoff coefficients of the plot with no vegetation varied from 3.0%to 58.0%,while in the vegetated plot,they showed variation from 1.0%to 21.0%.The annual specific sediment yield ranged from 4.6 to 138.7 kg/(hm^(2)•a)for the vegetated plot and from 34.9 to 608.5 kg/(hm^(2)•a)for the unvegetated one.These results indicate a 4 to 12 times higher soil loss on the unvegetated slope in relation to the vegetated one and demonstrate that natural Caatinga vegetation acts as an effective barrier against surface-transported sediments.Moreover,natural Caatinga vegetation present on the slope plays an important role in breaking connectivity between sediment flows from unpaved roads and the watershed drainage system.These findings indicate that investments in unpaved road and roadside slope restoration,not only enhance road infrastructure but also promote environmental gains by reducing the impact of erosion.展开更多
In the past few decades,ion engines have been widely used in deep-space propulsion and satellite station-keeping.The aim of extending the thruster lifetime is still one of the most important parts during the design st...In the past few decades,ion engines have been widely used in deep-space propulsion and satellite station-keeping.The aim of extending the thruster lifetime is still one of the most important parts during the design stage of ion engine.As one of the core components of ion engine,the grid assembly of ion optic systems may experience long-term ion sputtering in extreme electro-thermal environments,which will eventually lead to its structural and electron-backstreaming failures.In this paper,the current studies of the grid assembly erosion process are systematically analyzed from the aspects of sputtering damage process of grid materials,numerical simulations,and measurements of erosion characteristics of grid assembly.The advantages and disadvantages of various erosion prediction models are highlighted,and the key factors and processes affecting the prediction accuracy of grid assembly erosion patterns are analyzed.Three different types of experimental methods of grid assembly erosion patterns are compared.The analysis in this paper is of great importance for selecting the sputter-resistant grid materials,as well as establishing the erosion models and measurement methods to accurately determine the erosion rate and failure modes of grid assembly.Consequently,the working conditions and structure parameters of ion optic systems could be optimized based on erosion models to promote the ion engine lifetime.展开更多
This study evaluates the efficacy of sustainable erosion control using slag-based alkali-activated cement crusts under varying rainfall and wind conditions. The rainfall intensities ranged from 30 mm/h to 120 mm/h, wi...This study evaluates the efficacy of sustainable erosion control using slag-based alkali-activated cement crusts under varying rainfall and wind conditions. The rainfall intensities ranged from 30 mm/h to 120 mm/h, with durations ranging from 15 min to 90 min, and crust slopes of ∼2° (gentle) and 30° (steep). Wind tunnel experiments were conducted at wind velocities of 14 m/s, 21 m/s, and 28 m/s to investigate post-rainfall wind erodibility, along with changes in crust strength and microstructure analysis. The findings show the development of hydrated cementitious phases in alkali-activated material, which form around and between the particles during the alkaline activation process. Alkali-activated cement crusts significantly reduced erosion caused by rainfall and subsequent wind by several orders of magnitude. At the highest rainfall intensity of 120 mm/h, rainfall erosion was measured to be 1654.81 kg/m2 for untreated samples and 0.89 kg/m2 for treated samples, demonstrating a substantial 99.95% reduction in erosion due to the treatment. Similarly, at the highest wind speed tested, wind erosion was 122.75 kg/m2 for untreated samples and 0.095 kg/m2 for treated samples, indicating a significant 99.92% reduction in erosion due to the formation of an alkali-activated cement crust on the soil surface. However, exposure of the samples to 120 mm/h rainfall for 90 min resulted in a 5.2-fold increase in wind erosion compared to pre-rainfall conditions. Similarly, penetrometer results indicated a 37%–54% reduction in post-rainfall surface strength.展开更多
Changes in the coastline are characterized by accretion and erosion. The aim of this study is to contribute to a better understanding of the dynamics of the coastline and the study areas with a view to mitigating and ...Changes in the coastline are characterized by accretion and erosion. The aim of this study is to contribute to a better understanding of the dynamics of the coastline and the study areas with a view to mitigating and preventing the risk of coastal erosion in order to propose a coastal occupation model with planned development policies in the future. These phenomena lead to changes in the position of the coastline. After extraction, the satellite images are compiled, then superimposed and processed using Geographic Information Systems (GIS) for statistical calculation of coastline change rates. A morphosedimentary study is carried out using topography and sedimentology. The topographic method is used to calculate sediment volumes using monthly profiles. The sedimentological method is used to determine the granulometric variations in the morphological units by calculating sedimentological indices. With erosion rates of −2.13 m/yr and −2.17 m/yr respectively at Djiffère (Palmarin and Sangomar breccia) and Joal (Joal Fadhiouth and Ngazobil), the EPR index revealed a sediment deficit. Palmarin Ngallou and the island of Fadhiouth are undergoing accretion at rates of +1.43 m/yr and +1.14 m/yr respectively. From a topographical point of view, the respective accumulations of −13.74 m3/m of beach and −8.65 m3/m of beach at Djiffère and Joal respectively point to significant erosion on all the aerial beach units, while for the underwater beaches, accretion was noted with accumulations of +4.00 m3/m of beach and +5.94 m3/m at Djiffère and Joal respectively. As for the sedimentological results, the Mz index shows a decrease in grain size from the high beach to the surf zone. Some points show bimodal deposits, showing the impact of the dune on beach activity, confirmed by the dispersion on the Mz-sigma diagram. The three methods used in this work show that the Djiffère sector in Joal is dominated by erosion, even though accretion points can be noted.展开更多
基金primarily supported by the National Key Research and Development Program of China(Grant No.2024YFD1501201-3)partially supported by the National Key Research and Development Program of China(Grant No.2021YFD1500700)。
文摘Mass wasting is globally recognized as a key geomorphic agent in permanent gully expansion and greatly contributes to watershed sediment losses.Though its formation process has been assessed by some physical models,the occurrence and rainfall threshold have been rarely documented.In this study,rainfall-induced mass wasting events in two permanent gullies located in the Mollisols region of Northeast China,with Mollisols(gully 1)and sandy soil(gully 2)underneath were observed,and their differences were explored based on their soil strengths,hydraulic properties,excess topographies,and theoretical rainfall amounts.The sandy soil had a higher strength,faster pore water pressure dissipation rate,and lower suction stress at a specific soil moisture content compared to the black soil.The erosion thickness of the gully bed and sidewalls in gully 1 was shallower compared to gully 2.This was confirmed by the relationship between the erosion thickness and excess topography.The differences in the mass wasting erosion of the gully bed and sidewalls were due to the higher shear strength and well-drained hydraulic properties of the sandy soil compared to the black-soil.An infinite model was chosen to examine the temporal order of the mass wasting in the two gullies.It was found that the mass wasting in gully 2 occurred earlier than that in gully 1.This was likely due to the occurrence of an intense storm with less rainfall at the location of gully 2,while a light storm with heavier rainfall occurred in the location of gully 1.As Mollisols and sandy soil are the typical soil horizons in the Mollisols region worldwide,the results of this work could provide insightful knowledge for understanding the physical process of permanent gully expansion,which may be helpful for developing prediction models for sediment losses in some watersheds with vast Mollisols and highly developed gully system.
基金supported by the National Natural Science Foundation of China(Nos.12261131505,U2241274)the Russian Science Fund(No.23-49-00133)+3 种基金the Aeronautical Science Foundation of China(No.20240002053002)the Natural Science Basic Research Program of Shaanxi,China(No.2025JC-YBMS-005)the Key Research and Development Program of Shaanxi,China(No.2024GX-YBXM-037)the Basic Research Programs of Taicang,China(No.TC2024JC10)。
文摘As the main component of the aircraft leading edge,the radome is often the first to be hit by raindrops and cause structural damage when passing through a rain field.Rain resistant coating is usually applied to ensure the performance protection requirements.In order to clarify the rain erosion damage mechanism of radome coating and explore the influencing factors and mechanisms of coating material damage under different jet impact conditions,impact tests were conducted on three types of skin coating samples,and the damage mode was observed through electron microscopy characterization.The experimental results show that the typical morphology of rain erosion damage is annular surface peeling damage.The damage area and volume of the three coating samples increase with the continuous increase of raindrop impact velocity.The threshold velocity for initial damage to the coating is about 360 m/s;under the influence of the velocity component,the reduction in impact angle leads to a gradual reduction in the degree of damage to the sample.ABAQUS finite element simulation software was used to establish a constitutive model for coating rain erosion simulation and obtain the propagation law of stress waves during the impact process.The simulation results show that at the 75°impact angle,the jet impacts the surface of the specimen at different velocities,and as the impact velocity increases,the Mises equivalent stress on the surface shows an increasing trend,which is one of the main factors causing damage with increasing velocity.The effectiveness,rain erosion damage mode,and influencing mechanism of the model were verified based on the test results;the dynamic failure mechanism of the sample was further studied,and the stress propagation process at different impact angles was compared,revealing the influence mechanism and damage law of the impact angle on the high-speed raindrop impact of the material.
基金supports from the National Natural Science Foundation of China(Grant No.U20A20112)the Research Grants Council of the Hong Kong SAR Government,China(Grant Nos.T22-606/23-R and 16206923).
文摘Glacier landslide cascading hazards pose threats to communities and infrastructure,affected by complex processes including the amplification of mass flow volume through erosion and entrainment,transformation of hazard types,ice-water phase change,and enhanced mobility of the mass flow.Scientifically simulating these physical phenomena proves challenging.This study introduces GMFA(glacier mass flow analysis),an integrated numerical model that advances the field by:(1)proposing depth-averaged fluctuation energy and internal energy equations,(2)incorporating the ice-water phase change and the entrainment-deposition process,and(3)capturing their effects on mass flow runout characteristics.The model employs the finite volume method to solve the multi-physics coupled governing equations,enabling efficient large-scale simulations.The model is verified through three numerical tests covering flow dynamics,temperature evolution,and thermo-hydro-mechanical runout processes.The model is applied to analyze a hazard chain that occurred on 10 September 2020 on the Tibetan Plateau.The multi-scenario simulation results indicate an entrained mass volume of(4.95±0.11)×10^(5)m^(3),and a ratio of entrained mass volume to source material volume of 0.44.The solid concentration decreases from 0.6-0.7 to 0.1-0.15 with increasing runout distance,indicating a transition from avalanche to debris flood.The internal energy rises by(3-4)×10^(3)kJ/m^(3),driving rapid ice melting from 0.1 to 0.2 to near-zero concentration.The model effectively quantifies volume amplification,ice-water phase changes,and multi-hazard transformations.This model pushes the geoscience frontier,extending computational capability from single-to multi-hazard simulations and providing a powerful tool for analyzing glacier cascading hazards.
基金supported by the National Natural Science Foundation of China(No.52175414)the Natural Science Foundation of Jiangsu Province of China(No.BK20220134)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.NE2023002)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.KYCX24_0559)。
文摘During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this paper,the electrochemical dissolution behavior of Ti-6.5Al-2Zr-1Mo-1V(TA15)titanium alloy at without particle impact,low(15°)and high(90°)angle particle impact was investigated,and the influence of Al_(2)O_(3)particles on ECM was systematically expounded.It was found that under the condition of no particle erosion,the surface of electrochemically processed titanium alloy had serious pitting corrosion due to the influence of the passivation film,and the surface roughness(Sa)of the local area reached 10.088μm.Under the condition of a high-impact angle(90°),due to the existence of strain hardening and particle embedding,only the edge of the surface is dissolved,while the central area is almost insoluble,with the surface roughness(S_(a))reaching 16.086μm.On the contrary,under the condition of a low-impact angle(15°),the machining efficiency and surface quality of the material were significantly improved due to the ploughing effect and galvanic corrosion,and the surface roughness(S_(a))reached 2.823μm.Based on these findings,the electrochemical dissolution model of TA15 titanium alloy under different particle erosion conditions was established.
基金supported by National Natural Science Foundation of China(Grant No.42201080)Young Scientific and Technological Talents Program of Shaanxi Province(Grant No.2025ZC-KJXX-57)Special Scientific Research Program of the Shaanxi Provincial Department of Education(Grant No.21JK0967)。
文摘Freeze-thaw cycles(FTCs)have an important effect on soil aggregate stability by altering soil structures,thereby influencing soil wind and water erosion on the eastern Qinghai-Tibet Plateau.However,the effects of FTCs on the stability of these soils remain unclear.Here,we conducted freeze-thaw simulations in laboratory to investigate the effects of FTCs(0 to 15 cycles)on the wet-and dry-sieving aggregate stability of undisturbed sandy loam from Maqu county,which was treated with different initial soil moisture contents(1%to 25%in increments of 4%)and initial aggregate diameters(<2,2-5,5-10,and 10-15 mm).Results show that soil aggregates with initial diameters larger than 2 mm exhibit higher soil organic carbon contents(1.45%-1.57%)and silt contents(34.63%-35.52%)than those smaller than 2 mm(0.93%and 31.38%,respectively).The stability of both wet-and dry-sieving aggregates increases with larger initial diameters.Increasing initial soil moisture content from 1%to 25%reduces aggregate stability,with reductions of 2.4%-88.0%for wet-sieving aggregates and 2.1%-25.5%for dry-sieving aggregates(>2 mm).With increasing FTCs,wet-sieving aggregate(>2 mm)stability exhibits a fluctuating upward trend,with increases of 79.2%-87.4%after 15 FTCs,while dry-sieving aggregate(>2 mm)stability decreases significantly(5.7%-21.7%)upon the first FTC and remains unchanged thereafter.The stability of both the wet-and dry-sieving aggregates smaller than 2 mm remains unchanged with increasing FTCs(p>0.05).SOC content decreases by 22.3%on average with increasing FTCs from 1 to 15 and shows no significant correlations with wet-and dry-sieving aggregate stability.Higher silt content(r=0.39,p<0.05)and lower sand content(r=-0.38,p<0.05)enhances the wet-sieving aggregate stability of sandy loam.Frequent FTCs tend to improve wet-sieving aggregate stability but reduce dry-sieving aggregate stability in the sandy loam.The findings provide certain guidance for preventing freeze-thaw-induced wind erosion.
基金support from the project supported by the National Natural Science Foundation of China(Grant No.52402034)the Science and Technology Innovation Team Foundation of Hubei Province(Grant No.T2023001)+1 种基金the Natural Science Foundation of Hubei Province(Grant No.2023BAB106)the Natural Science Foundation of Wuhan(Grant No.2024040701010051).
文摘To resolve severe slag penetration and erosion in Al_(2)O_(3)-SiC-C refractories during high scrap ratio iron ladle operation,a novel strategy utilizing exogenous MgAl_(2)O_(4) spinel as a sacrificial FeO_(x) scavenger was proposed.Al_(2)O_(3)-SiC-C refractories produced with plate-like corundum,silicon carbide,and flake graphite incorporating MgAl_(2)O_(4) additives were cured at 1400℃ in the condition of carbon embedding.The impacts of additives on phase composition,microscopic morphology,and performance of materials were studied.The results indicated that Al_(2)O_(3)-SiC-C refractories with the addition of 2 wt.%MgAl_(2)O_(4) exhibited a smaller oxidation area after oxidation tests compared to samples without MgAl_(2)O_(4),resulting in 28%improvement in oxidation resistance compared to blank samples.In the erosion test,the results informed that adding 4 wt.%MgAl_(2)O_(4) induced significant interfacial slag modification:MgAl_(2)O_(4) dynamically dissolved FeO_(x) to form protective Mg(Fe,Al)_(2)O_(4) solid solution on the slag-refractory interface.This sacrificial dissolution effectively immobilized FeO_(x),elevated local slag viscosity,and fundamentally inhibited slag penetration and matrix dissolution.The erosion index decreased from 50%in the blank group to 27.4%.
基金funded by the Science and Technology Plan for the Belt and Road Innovation Cooperation Project of Jiangsu Province,China(No.BZ2023003)the National Key Research and Development Program of China(No.2021YFD1500202)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA28010100)the“14th Five-Year Plan”Self-Deployment Project of the Institute of Soil Science,Chinese Academy of Sciences(No.ISSAS2418)the National Natural Science Foundation of China(No.42107334)。
文摘Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.
基金the National Natural Science Foundation of China(42377170,42407212)the National Funded Postdoctoral Researcher Program(GZB20230606)+3 种基金the Postdoctoral Research Foundation of China(2024M752679)the Sichuan Natural Science Foundation(2025ZNSFSC1205)the National Key R&D Program of China(2022YFC3005704)the Sichuan Province Science and Technology Support Program(2024NSFSC0100)。
文摘Wildfires significantly disrupt the physical and hydrologic conditions of the environment,leading to vegetation loss and altered surface geo-material properties.These complex dynamics promote post-fire gully erosion,yet the key conditioning factors(e.g.,topography,hydrology)remain insufficiently understood.This study proposes a novel artificial intelligence(AI)framework that integrates four machine learning(ML)models with Shapley Additive Explanations(SHAP)method,offering a hierarchical perspective from global to local on the dominant factors controlling gully distribution in wildfireaffected areas.In a case study of Xiangjiao catchment burned on March 28,2020,in Muli County in Sichuan Province of Southwest China,we derived 21 geoenvironmental factors to assess the susceptibility of post-fire gully erosion using logistic regression(LR),support vector machine(SVM),random forest(RF),and convolutional neural network(CNN)models.SHAP-based model interpretation revealed eight key conditioning factors:topographic position index(TPI),topographic wetness index(TWI),distance to stream,mean annual precipitation,differenced normalized burn ratio(d NBR),land use/cover,soil type,and distance to road.Comparative model evaluation demonstrated that reduced-variable models incorporating these dominant factors achieved accuracy comparable to that of the initial-variable models,with AUC values exceeding 0.868 across all ML algorithms.These findings provide critical insights into gully erosion behavior in wildfire-affected areas,supporting the decision-making process behind environmental management and hazard mitigation.
基金financially supported by the National Natural Science Foundation of China(Grant No.52301339)the Natural Science Foundation of Fujian Province(Grant No.2021J05004)+1 种基金the State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation,Tianjin University(Grant No.HESS-2402)the Fundamental Research Funds for the Central Universities(Grant No.20720240038).
文摘A carcass is the innermost layer of a deep-sea unbonded flexible pipe,which is in direct contact with the gas/liquid-solid multi-phase flow.Considering that stress-accelerated erosion is common for carcasses,this study proposes a general model and simulation method for stress-accelerated erosion(SE)of carcasses under external water pressure.First,an SE model suitable for 316 stainless steel was developed,which was then used for stress-erosion simulation for an external pressurized carcass,and the solid domain,fluid domain and rough inner surface of the carcass were carefully considered.Moreover,a simplified model(equivalent smooth pipe)was also established on the basis of the main geometric characteristics of the carcass,and the stress-erosion characteristics under different operating conditions,including the effects of the elastic stress level,flow velocity,particle diameter and concentration,were carefully compared,and the key factors governing the elastic stress-erosion of the carcass were discussed.Finally,a modified geometry factor(GF)for carcasses was proposed considering the stress acceleration effect.
基金supported by the National Natural Science Foundation of China(Nos.U2241240,12172045 and 12221002)the Opening Fund of State Key Laboratory of Explosion Science and Technology of Beijing Institute of Technology,China(No.ZDKT23-02)。
文摘Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.
基金funded by the Technology Funding Scheme of China Construction Second Engineering Bureau LTD(2020ZX150002)the National Natural Science Foundation Project of China(12262018).
文摘To address the challenges posed by tunnel construction in the alpine region,silica fume mixed concrete is commonly used as a construction material.The correlation between silica fume content and the lining life requires immediate investigation.In view of this phenomenon,the durability of unit lining concrete is predicted by analyzing three key indicators:carbonation depth,relative dynamic elastic modulus,and residual quality.This prediction is achieved by integrating the Entropy Weight Method,Grey theory life prediction model and BP artificial neural networks using data from tests and predictions of these indicators.Then,the Entropy Weight-Grey theory-BP Network Model is compared with other methods to analyze the predicted life.Finally,verify the sci-entificity of this model,and the optimum silica fume content of unit concrete lining is verified.The results showed,1)The addition of silica fume will accelerate the carbonization of unit concrete lining,and slow down the freeze-thaw cycle and sulfate erosion.2)The utilization of artificial neural networks is essential for enhancing the realism of the data,as it emphasizes the significance of silica fume content.3)Silica fume content of 10%results in the longest life and is the most suitable for lining construction.4)A comparison between single-factor and multi-factor predictions indicates that the multi-factor approach yields a longer maximum life.This improvement can be attributed to the inclusion of additional factors,such as freeze-thaw cycles and carbonation,which enhance the predicted life when employing these methods.In conclusion,the Entropy Weight-Grey Theory-BP Network life prediction Model is well-suited for tunnel lining in the alpine sulfate area of northwest China.
基金Project(2021YJ059)supported by the Research Project of China Academy of Railway Sciences。
文摘The study aims to investigate the carbonated water erosion mechanism of lining concrete in tunnels traversing karst environment and enhance its resistance.In this study,dynamic carbonated water erosion was simulated to assess erosion depth,microstructure,phase migrations,and pore structure in various tunnel lining cement-based materials.Additionally,Ca^(2+)leaching was analyzed,and impact of Ca/Si molar ratio in hydration products on erosion resistance was discussed by thermodynamic calculations.The results indicate that carbonated water erosion caused rough and porous surface on specimens,with reduced portlandite and CaCO_(3) content,increased porosity,and an enlargement of pore size.The thermodynamic calculations indicate that the erosion is spontaneous,driven by physical dissolution and chemical reactions dominated by Gibbs free energy.And the erosion reactions proceed more spontaneously and extensively when Ca/Si molar ratio in hydration products was higher.Therefore,cement-based materials with higher portlandite content exhibit weaker erosion resistance.Model-building concrete,with C-S-H gel and portlandite as primary hydration products,has greater erosion susceptibility than shotcrete with ettringite as main hydration product.Moreover,adding silicon-rich mineral admixtures can enhance the erosion resistance.This research offers theory and tech insights to boost cement-based material resistance against carbonated water erosion in karst tunnel engineering.
基金Supported by National Science and Technology Major Project,No.2024ZD0521002The Innovation Team Project of Traditional Chinese Medicine of Liaoning Province,No.LNZYYCXTD-CCCX-003+1 种基金General Program of the National Natural Science Foundation of China,No.82074296Construction Project of Inheritance Studios of Famous Chinese Medicine Experts in China,No.[2022]No.75.
文摘This article focuses on the clinical efficacy and mechanism of action of heatclearing and detoxifying traditional Chinese medicines(TCMs)in the treatment of erosive gastritis,providing a reference for the treatment of this disease.In the clinical treatment of erosive gastritis,TCM combinations such as Qing Gastric San,Semixia Diarrheal Heart Soup,and single-flavored heat-clearing and detoxifying drugs such as dandelion and Huanglian have specific efficacies and effectively improve the patient's symptoms,including killing or inhibiting Helicobacter pylori,reducing inflammatory reactions,protecting the gastric mucosa,inhibiting gastric acid secretion,regulating gastrointestinal hormones,and regulating immune function,playing therapeutic roles through multi-level and multi-target mechanisms.Thus,heat-clearing and detoxifying TCMs have broad application prospects in clinical practice for erosive gastritis.
文摘To verify the wear resistance and erosion resistance of Ti-doped Ta_(2)O_(5)coating(TTO),a series of TTOs were prepared by magnetron sputtering technology by controlling the power of the Ti target.The change of growth structure,microstructure,and tribological properties of TTOs with Ti target power was studied.After the erosion test,the variation of erosion damage behavior of TTOs with mechanical properties under different erosion conditions was further studied.The results show that the TTOs eliminate the roughness,voids,and defects in the material due to the mobility of the adsorbed atoms during the growth process,and a flat and dense smooth surface is obtained.Tribological tests show that the TTOs are mainly characterized by plastic deformation and microcrack wear mechanism.Higher Ti target power can improve the wear resistance of TTOs.Erosion test results reveal that the impact crater,furrow,micro-cutting,brittle spalling,and crack formation are the main wear mechanisms of the TTOs samples under erosion conditions.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFD1501102)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20220163)+2 种基金the Jiangxi Province Natural Science Foundation(Grant No.20224BAB203031)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA0440202)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2023327)。
文摘Soil erosion is the primary factor causing the loss of soil resources and land degradation.Clarifying the current status of soil erosion in China and the characteristics of future changes under different pathways of development is important to the global management of soil resources,food security,and ecosystem services.We used the revised universal soil loss equation and the most recent and reliable soil and environmental data to characterize soil erosion in China at present and under typical Shared Socioeconomic Pathways and Representative Concentration Pathways(i.e.,SSP1–2.6 and SSP5–8.5)in the medium-and long-term future(2050 and 2100).The current average rate of soil erosion in China was 14.78 t ha^(-1)yr^(-1),with a total amount of about 14.0 Pg yr^(-1).The amount of total erosion increased by 5.0%,10.8%,9.9%,and 25.9%for scenarios 2050_SSP1–2.6,2050_SSP5–8.5,2100_SSP1–2.6,and 2100_SSP5–8.5,respectively,compared to the baseline amount in 2010.The contribution of climate change and land use to the increase in erosion ranged from 9.5%to 31.5%and-6.95%to-1.78%,respectively,with the contribution of climate change about 2.36-to 7.54-fold larger than the contribution of land use.Converting arable barren land into forest and grassland or adopting conservation tillage practices for farmland,could nevertheless effectively offset the increase in erosion under the four future scenarios.This study provides data and a scientific basis for managing soil erosion in China and provides a useful reference for conserving global land resources and formulating policies to cope with climatic and environmental changes.
文摘The increased erosion of mangrove forests has alarmed the government about the damage to both the economy and livelihoods.To evaluated forest and land erosion the coast.Based on survey data is divided into five levels(F1:no erosion;F2:little erosion;F3:moderate erosion;F4:high erosion;F5:strong erosion),and ecological conditions,the coast is divided into sub-regions for investigation.From the surveyed indicators at each erosion level,forest structure is analyzed for comparison.The erosion level is defined as an erosion function(Er)from 1 to 5(+),where(1)parameters include the number of trees per hectare(Ntr/ha),height to top(Ht),trunk diameter at 1.3 m(D1.3),tree canopy diameter(Dc),and width of the forest range(Wf);(2)land erosion is a function(Erl=Erlte+Erlsa+Erlsi+Erlcl),with parameters including erosion by terrain(Erlte),sand(Erlsa),silt(Erlsi),and clay(Erlcl);and(3)climate change leading to erosion is an inverse function(Cl)from 1 to 5(-),with parameters including erosion by rainfall(Clra),wind(Clwi),waves(Clwa),and tide(Clti).The resulting function output is Er=(Erf+Erl)-Cl.On eroded forest land,species were tested under climate change conditions and their growth in the next rainy season to assess survival rates affected by rainfall,waves,wind,and tides.These results help to plan planting mangrove forest anti-erosion models and construct a theoretical function of mangrove erosion and proposes restore forests using pioneer species.
基金the National Council for Scientific and Technological Development (CNPq) for funding the field studies and for the research productivity fellowship (CNPq/PQ) awarded to Pedro Henrique Augusto MEDEIROS and José Carlos de ARAúJOthe Coordination for the Improvement of Higher Education Personnel (CAPES) for the doctoral scholarship awarded to Teresa Raquel Lima FARIAS (2117/13-4)the Foundation for the Support of Scientific and Technological Development in the State of Ceará (FUNCAP) for the master scholarship awarded to Maria Thereza Rocha CHAVES。
文摘Vegetation plays a major role in soil protection against erosion effects,and studies have also highlighted its importance in retaining sediments from roadside slopes.Yet,hydro-sedimentological studies under natural precipitation conditions are still scarce in semi-arid areas due to difficulties in monitoring the few and very concentrated precipitation events.Quantifying sediment connectivity and yield at watershed scale,often highly impacted by the erosion of unpaved roads,is necessary for management plans.This study aims to evaluate the efficiency of native vegetation on roadside slope segments in Caatinga biome in retaining sediments and conserving the soil in a semi-arid area of Brazil.Surface runoff,sediment concentration,and yield measurements were measured from 34 natural precipitation events in four years on two slopes with and without vegetation.The runoff coefficients of the plot with no vegetation varied from 3.0%to 58.0%,while in the vegetated plot,they showed variation from 1.0%to 21.0%.The annual specific sediment yield ranged from 4.6 to 138.7 kg/(hm^(2)•a)for the vegetated plot and from 34.9 to 608.5 kg/(hm^(2)•a)for the unvegetated one.These results indicate a 4 to 12 times higher soil loss on the unvegetated slope in relation to the vegetated one and demonstrate that natural Caatinga vegetation acts as an effective barrier against surface-transported sediments.Moreover,natural Caatinga vegetation present on the slope plays an important role in breaking connectivity between sediment flows from unpaved roads and the watershed drainage system.These findings indicate that investments in unpaved road and roadside slope restoration,not only enhance road infrastructure but also promote environmental gains by reducing the impact of erosion.
基金co-supported by the National Key R&D Program of China(No.2022YFB3403500)the National Natural Science Foundation of China(No.NSFC52202460)the China Postdoctoral Science Foundation(Nos.2021M690392,2021TQ0036,and 2023TQ0031)。
文摘In the past few decades,ion engines have been widely used in deep-space propulsion and satellite station-keeping.The aim of extending the thruster lifetime is still one of the most important parts during the design stage of ion engine.As one of the core components of ion engine,the grid assembly of ion optic systems may experience long-term ion sputtering in extreme electro-thermal environments,which will eventually lead to its structural and electron-backstreaming failures.In this paper,the current studies of the grid assembly erosion process are systematically analyzed from the aspects of sputtering damage process of grid materials,numerical simulations,and measurements of erosion characteristics of grid assembly.The advantages and disadvantages of various erosion prediction models are highlighted,and the key factors and processes affecting the prediction accuracy of grid assembly erosion patterns are analyzed.Three different types of experimental methods of grid assembly erosion patterns are compared.The analysis in this paper is of great importance for selecting the sputter-resistant grid materials,as well as establishing the erosion models and measurement methods to accurately determine the erosion rate and failure modes of grid assembly.Consequently,the working conditions and structure parameters of ion optic systems could be optimized based on erosion models to promote the ion engine lifetime.
文摘This study evaluates the efficacy of sustainable erosion control using slag-based alkali-activated cement crusts under varying rainfall and wind conditions. The rainfall intensities ranged from 30 mm/h to 120 mm/h, with durations ranging from 15 min to 90 min, and crust slopes of ∼2° (gentle) and 30° (steep). Wind tunnel experiments were conducted at wind velocities of 14 m/s, 21 m/s, and 28 m/s to investigate post-rainfall wind erodibility, along with changes in crust strength and microstructure analysis. The findings show the development of hydrated cementitious phases in alkali-activated material, which form around and between the particles during the alkaline activation process. Alkali-activated cement crusts significantly reduced erosion caused by rainfall and subsequent wind by several orders of magnitude. At the highest rainfall intensity of 120 mm/h, rainfall erosion was measured to be 1654.81 kg/m2 for untreated samples and 0.89 kg/m2 for treated samples, demonstrating a substantial 99.95% reduction in erosion due to the treatment. Similarly, at the highest wind speed tested, wind erosion was 122.75 kg/m2 for untreated samples and 0.095 kg/m2 for treated samples, indicating a significant 99.92% reduction in erosion due to the formation of an alkali-activated cement crust on the soil surface. However, exposure of the samples to 120 mm/h rainfall for 90 min resulted in a 5.2-fold increase in wind erosion compared to pre-rainfall conditions. Similarly, penetrometer results indicated a 37%–54% reduction in post-rainfall surface strength.
文摘Changes in the coastline are characterized by accretion and erosion. The aim of this study is to contribute to a better understanding of the dynamics of the coastline and the study areas with a view to mitigating and preventing the risk of coastal erosion in order to propose a coastal occupation model with planned development policies in the future. These phenomena lead to changes in the position of the coastline. After extraction, the satellite images are compiled, then superimposed and processed using Geographic Information Systems (GIS) for statistical calculation of coastline change rates. A morphosedimentary study is carried out using topography and sedimentology. The topographic method is used to calculate sediment volumes using monthly profiles. The sedimentological method is used to determine the granulometric variations in the morphological units by calculating sedimentological indices. With erosion rates of −2.13 m/yr and −2.17 m/yr respectively at Djiffère (Palmarin and Sangomar breccia) and Joal (Joal Fadhiouth and Ngazobil), the EPR index revealed a sediment deficit. Palmarin Ngallou and the island of Fadhiouth are undergoing accretion at rates of +1.43 m/yr and +1.14 m/yr respectively. From a topographical point of view, the respective accumulations of −13.74 m3/m of beach and −8.65 m3/m of beach at Djiffère and Joal respectively point to significant erosion on all the aerial beach units, while for the underwater beaches, accretion was noted with accumulations of +4.00 m3/m of beach and +5.94 m3/m at Djiffère and Joal respectively. As for the sedimentological results, the Mz index shows a decrease in grain size from the high beach to the surf zone. Some points show bimodal deposits, showing the impact of the dune on beach activity, confirmed by the dispersion on the Mz-sigma diagram. The three methods used in this work show that the Djiffère sector in Joal is dominated by erosion, even though accretion points can be noted.
