Extensive engineering experience and research findings suggest that rock mass instability is typically attributed to human engineering activities and natural disturbances,resulting in general dynamic mechanical proper...Extensive engineering experience and research findings suggest that rock mass instability is typically attributed to human engineering activities and natural disturbances,resulting in general dynamic mechanical properties.This is attributed to external interference resulting from the extensive use of the mechanical and blasting techniques necessary for mineral extraction.Quantifying the impact of dynamic disturbances on rock deformation behavior is essential for comprehending the long-term response of surrounding rock during excavation.This study placed the rock to sustained pressure and investigated the impact of varying hammer heights and dry and wet(W-D)damage on its shear failure behavior.This study investigated the fatigue disturbance studies on W-D damaged sandstone samples via W-D equipment,a disturbance creep device,digital image correlation(DIC),and acoustic emission(AE)technology.The experimental findings suggest that acoustic emission sensors can be utilized to quantify the internal damage of rock samples during cyclic impact,whereas DIC technology(optical measurement)is capable of capturing the surface crack propagation of samples.Under repeated impact and the combined action of W-D conditions,the bearing capacity of sandstone decreases,whereas the deformation capacity increases.Furthermore,the W-D cycles and impact strength are inversely related to the fatigue life.The intensity of W-D damage and disturbances further accelerates the development and propagation of cracks under cyclic disturbances.The research results are of preventive significance to ensure the safety and sustainable development of engineering construction.展开更多
The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated.The distribution,morphology,size,and number density of shrinkage porosities were analyzed under different cool...The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated.The distribution,morphology,size,and number density of shrinkage porosities were analyzed under different cooling rates.The relationship between shrinkage porosities and microstructure characteristics was discussed in terms of temperature conditions,feeding channel characteristics,and feeding capacity.Further,the feeding behavior of the residual liquid phase in the solid skeleton was quantified by introducing permeability.Results show a strong correlation between the solid microstructure skeleton and shrinkage porosity characteristics.An increase in permeability corresponds to a declining number density of shrinkage porosities.This study aims to provide a more complete understanding how to reduce shrinkage porosities by controlling microstructure characteristics.展开更多
The soft actuator is characterized by high safety,flexibility,and adaptability.It is capable of both active and passive defor-mations.This paper presents a discrete degree of freedom(DOF)method for soft actuators to r...The soft actuator is characterized by high safety,flexibility,and adaptability.It is capable of both active and passive defor-mations.This paper presents a discrete degree of freedom(DOF)method for soft actuators to reveal DOF characteristics.The method draws on the superposition mechanism of the deformation characteristics of the sarcomere in the skeletal muscles of living organisms.Firstly,the multi-DOF deformation characteristics of the soft actuator are discretized into superimposed combinations of single-DOF micro-units.Then,the soft actuator was determined to contain deformation characteristics such as extension-contraction,bending,and twisting.Eighteen types of micro-units with basic deforma-tion characteristics were obtained depending on the axis and orientation.Further,the mapping relationship between the combination of micro-units and the motion characteristics of the soft actuator based on the GF set theory was established.Finally,an active-passive DOF co-structured soft actuator(APCSA)was developed.The graphical approach analyzes the experimental results,and it can be concluded that active and passive DOFs can coexist in the composite deformation of the soft actuator.展开更多
Standardization is necessary for the early industrialization of the new materials and technology.It is achieved by having agreed practices for the measurement of properties and other characteristics.The promising use ...Standardization is necessary for the early industrialization of the new materials and technology.It is achieved by having agreed practices for the measurement of properties and other characteristics.The promising use of graphene-based materials in fields like electronics,energy,and composites has resulted in standards for their nomenclature,the measurement of key characteristics,and their specification,etc.Among these,standards for measuring the key characteristics are crucial.The critical parameters are the number of layers,the type and concentration of defects and functional groups,elemental composition,sheet resistance,and carrier mobility.Standards for characterizing these have been analyzed by the International Organization for Standardization Technical Committee in ISO/TC229 and the International Electrotechnical Commission Technical Committee in IEC/TC113.These give details of applicable or preferred samples,the fundamental principles of the techniques,specific precautions,and points for attention in the relevant standards.The pivotal role of the ISO/TC229 and IEC/TC113 standards is considered and challenges and future trends are outlined.展开更多
39 soil samples surrounding a lead-zinc mining area in Guangxi were collected,and the contents of Pb,Hg,Cd,Cr,As,Cu,Zn,and Ni were determined to investigate the pollution characteristics and sources of heavy metals.Ar...39 soil samples surrounding a lead-zinc mining area in Guangxi were collected,and the contents of Pb,Hg,Cd,Cr,As,Cu,Zn,and Ni were determined to investigate the pollution characteristics and sources of heavy metals.ArcGIS inverse distance weight difference method was used to analyze the characteristics of pollution distribution,and single-factor pollution index,Nemerow comprehensive pollution index,ground accumulation index,and potential ecological risk index were selected to evaluate the characteristics of heavy metal pollution.Based on correlation analysis,the absolute principal component-multiple linear regression(APCS-MLR)and positive definite matrix factorization(PMF)models were used to analyze the sources of soil heavy metals.The results showed that the average concentrations of all eight heavy metals exceeded both national and Guangxi soil background values.Hg,Cd,and Zn exhibited high variation(greater than 0.5),indicating significant external disturbances,and their spatial distribution was closely related to mining activity locations.The single-factor pollution index evaluation indicated varying degrees of pollution risk for Cd,Zn,and As,with Cd and Zn being the most severe pollutants,as 69.23%and 30.77%of the samples fell into the moderate pollution or higher category.The geoaccumulation index analysis ranked the mean pollution levels of the eight elements as follows:Zn>Cd>Ni>Pb>Cu>Cr>Hg>As,with Cd and Zn showing the most severe contamination,and 51.28%of the samples exhibiting moderate or higher pollution levels.The Nemerow comprehensive pollution index evaluation showed that 74.35%of soil samples were classified as moderate to heavy pollution.The potential ecological risk index assessment indicated significant ecological risks posed by Cd and Zn,with 82.05%and 5.12%of the samples classified as causing strong to extreme ecological risks,respectively.The source apportionment analysis revealed minor differences between the two models.The APCS-MLR model identified three pollution sources and their contribution rates:anthropogenic mining sources(31.13%),parent material sources(40.38%),and unidentified sources(28.49%).The PMF model identified three pollution sources with contribution rates of anthropogenic mining sources(26.10%),parent material sources(46.96%),and a combined traffic and agricultural source(26.61%).Pb,Hg,Cd,and Zn mainly originated from mining activities;Cr,As,and Ni were primarily derived from the parent material,while Cu was predominantly attributed to traffic and agricultural sources.These findings provide a scientific basis for the prevention and control of heavy metal pollution in mining areas.展开更多
This paper studies the structural response of high-speed train wipers under the combined action of complex flow fields and scraping actions.The stress concentration areas are determined through simulation analysis,and...This paper studies the structural response of high-speed train wipers under the combined action of complex flow fields and scraping actions.The stress concentration areas are determined through simulation analysis,and the stress and aerodynamic load measurement points are reasonably arranged accordingly.The actual measurement is carried out in combination with the operating conditions of the existing lines.The stress variations and spectral characteristics of the train under different speed levels(80,160,180,200 km/h),tunnel entry and exit,and scraper action conditions were compared and analyzed.The stress amplification factors under tunnel intersection and scraper action were obtained,providing boundary conditions for the design of wipers for highspeed s.The research results show that the maximum stress of the wiper structure obtained through simulation calculation is concentrated at the connection of the wiper arm.Structural stress increases with the rise of speed grade.The stress increases by 1.11 times when the tunnel meets.When the scraper operates,the stress on the scraper arm increases by 4.1–7.6 times.Due to the broadband excitation effect of the aerodynamic load,the spectral energy of the structure is relatively high at the natural frequency,which excites the natural mode of the wiper.展开更多
As vital hydraulic infrastructures,concrete dams demand uncompromising safety assurance.Seismic effect commonly serves as a potential factor contributing to the damage of concrete dams,making seismic performance analy...As vital hydraulic infrastructures,concrete dams demand uncompromising safety assurance.Seismic effect commonly serves as a potential factor contributing to the damage of concrete dams,making seismic performance analysis crucial for structural integrity.Numerical simulation based on damage mechanics is usually considered as the approach for investigating the seismic damage behavior of concrete dams.To address the limitations of existing studies and extract the key dynamic characteristics of concrete arch dams,a concrete elastoplastic damage mechanics model is adopted,a seismic load input technique involving the viscoelastic boundary along with equivalent nodal forces is generated,and a spring-contact pair simulation technique formodeling the transverse joints of arch dams is developed.The damage process of an arch dam under the classic Koyna seismic load is simulated,with the damage evolution process under seismic action being characterized.The middle sections of the arch dam near the upper portion are considered regions prone to damage under seismic action.Furthermore,the nonlinear dynamic characteristics caused by the opening and closing collision between transverse joints of the arch damunder strong seismic action are extracted.The extracted dynamic characteristic provides a manifestation for the dynamic damage diagnosis of arch dams based on seismic responses.展开更多
In this study,the dynamic characteristics and microstructures of lacustrine soft clays were studied.Dynamic character tests were conducted on undisturbed,remolded,and saturated lacustrine soft clays,using a dynamic tr...In this study,the dynamic characteristics and microstructures of lacustrine soft clays were studied.Dynamic character tests were conducted on undisturbed,remolded,and saturated lacustrine soft clays,using a dynamic triaxial tester.A scanning electron microscope(SEM)was employed to assess the soil samples after dynamic testing.The results indicate that the dynamic characteristics of lacustrine soft clay were significantly affected by confining pressure and water content.A quantitative relationship was established among confining pressures,water content,and the dynamic shear modulus ratio.The dynamic characteristic parameters of undisturbed,remolded and saturated soil are obviously different,and the original structure can enhance the shear strength of soil.By comparing the results with those from other studies,we found that the dynamic characters of soft clays were considerably varied in different regions,and lacustrine soft clays had a larger dynamic shear modulus ratio and a smaller damping ratio when the dynamic shear strain was large.Using IPP software to process the microstructural images,we found that the soil was dominated by small pores and medium particles,and the roundness of pores and particles had an apparently positive correlation with the maximum diameter.Moreover,the pores and particles of the soil showed fractal characteristics and directionality,and the fractal dimensions and probability entropy were strongly correlated with the macrostructural parameters.Finally,we developed a prediction model for macrostructural and microstructural parameters.展开更多
In response to the Ministry of Education’s requirements for building distinctive model software schools,Software College of Northeastern University and Shenzhen Kingdom Technology Co.,Ltd.jointly developed the specia...In response to the Ministry of Education’s requirements for building distinctive model software schools,Software College of Northeastern University and Shenzhen Kingdom Technology Co.,Ltd.jointly developed the specialized course“Application and Practice of RPA Technology in FinTech”.Addressing pain points in financial digital transformation,the course integrates robotic process automation(RPA)principles,financial domain knowledge,and RPA platform practice into a“technology-scenario-capability”trinity teaching system.Through 64 credit hours of integrated theory and practice,it covers RPA fundamentals,financial applications,RPA operations(including core skills like Web/desktop automation),and AI integration,cultivating students’ability to design and implement automated financial workflows.It innovatively features a RPA simulation platform,30+financial case studies,and modular task resources,creating a“teacher-machine-student”interactive model.Practice demonstrates the course effectively enhances students’integration of technical application and business acumen,providing a scalable paradigm for cultivating interdisciplinary FinTech talent.展开更多
Groundwater is a key part of the terrestrial ecosystem,but it is vulnerable to pollution in the context of chemical industry development.Treating contaminated groundwater is challenging due to its stable water quality...Groundwater is a key part of the terrestrial ecosystem,but it is vulnerable to pollution in the context of chemical industry development.Treating contaminated groundwater is challenging due to its stable water quality,hidden contamination,and complex treatment requirements.Current research focuses on advanced treatment technologies,among which the advanced oxidation process(AOPs) of peroxomonosulfate(PMS) has great potential.Although there are many reviews of PMS-based AOP,most of them focus on surface water.This review aims to explore the activation reaction of PMS to groundwater by in-situ chemical oxidation(ISCO) technology,further study the reaction mechanism,compare the treatment effect of characteristic pollutants in the groundwater of the chemical industry park,propose new activation methods and catalyst selection,and provide guidance for future groundwater treatment research.展开更多
The coal dynamic characteristic stress identification under dynamic load is important for guiding underground mineral mining and predicting underground dynamic disasters.In this article,the dynamic compression test of...The coal dynamic characteristic stress identification under dynamic load is important for guiding underground mineral mining and predicting underground dynamic disasters.In this article,the dynamic compression test of anthracite under five strain rates is carried out,the evolution law of three kinds of crack characteristic stress is analyzed,and a prediction model of the crack characteristic stress threshold considering the strain rate effect is established.Then,the rationality of crack characteristic stress under dynamic loading is discussed from the damage evolution standpoint,and the crack extension response mechanism during dynamic compression of anthracite is discussed.The result shows that the crack characteristic stress threshold is significantly influenced by the strain rate.The three characteristic stress thresholds are positively correlated with the strain rate,but the ratios to the crest stress gradually decrease.The increase in the strain rate strongly contributes to the crack extension behavior of anthracite.In the crack unstable extension phase,because of the increase of the strain rate,anthracite shows more energy dissipation under the same deformation in association with the stress concentration effect and the dynamic strength enhancement effect.The crack propagation rate is increased,the crack propagation path of the section is more complex,and more severe damage occurs before the dynamic failure of anthracite,which leads to even more severe damage.展开更多
The respiratory-circulatory system, including organs such as the nose, pharynx, larynx, trachea, bronchi, and heart, is an organic community responsible for ventilation and gas exchange. The integrity of its anatomica...The respiratory-circulatory system, including organs such as the nose, pharynx, larynx, trachea, bronchi, and heart, is an organic community responsible for ventilation and gas exchange. The integrity of its anatomical structure directly affects the evolution of pathological processes, and the analysis of their correlation is a core entry point for clinical disease diagnosis, treatment, and mechanism research. Based on this, this paper mainly explores the correlation between the anatomical and pathological characteristics of the respiratory-circulatory system, aiming to provide anatomical and pathological theoretical support for clinical accurate diagnosis, targeted therapy, and prognosis evaluation.展开更多
Aiming at the problem of innovative talent training in the industry field in characteristic software colleges,combined with the actual situation of Software College of Northeastern University,this paper analyzes the c...Aiming at the problem of innovative talent training in the industry field in characteristic software colleges,combined with the actual situation of Software College of Northeastern University,this paper analyzes the construction requirements of characteristic talent training mode and training scheme,puts forward the reform of characteristic software innovative talent training scheme integrating production and education,and takes the characteristic direction of financial technology as an example to introduce the curriculum construction based on industry-education integration and school-enterprise cooperation.展开更多
MgO has been shown to facilitate the precipitation of MgO-rich crystalline phases within the MgO-CaO-Al_(2)O_(3)-SiO_(2)(MCAS)glassy inclusion system,which possesses a high liquidus temperature and a significant Young...MgO has been shown to facilitate the precipitation of MgO-rich crystalline phases within the MgO-CaO-Al_(2)O_(3)-SiO_(2)(MCAS)glassy inclusion system,which possesses a high liquidus temperature and a significant Young’s modulus.The underlying linkage between the structural evolution and the crystallization characteristics of the MCAS system was systematically investigated using molecular dynamics simulation and thermodynamic calculation.The results revealed that Mg^(2+) ions played a dual role,constructing networks through the formation of tricluster oxygens while consuming bridging oxygens(BOs)in a mechanism similar to Ca^(2+) ions.However,despite this dual role,the network connectivity was still decreased with the increase in MgO/(MgO+Al_(2)O_(3))(M/(M+A))and CaO/(CaO+SiO_(2))(C/(C+S))ratios,primarily due to the reduction in BOs.This microscopic structural evolution resulted in a reduction in viscosity and an enhancement of crystallization ability.Furthermore,the remarkable diffusion capability of Mg^(2+) ions,coupled with the increased proportion of 6-coordinated Mg^(2+)ions,unveiled the mechanism underlying the precipitation of MgSiO_(3) and Mg_(2)SiO_(4) crystals,which exhibited high Young’s moduli of 165.23 and 196.67 GPa,respectively.To prevent the precipitation of MgO-rich crystalline phases,it was crucial to maintain the M/(M+A)ratio below 0.42 and the C/(C+S)ratio below 0.16 within the MCAS system.展开更多
Objective:For patients with hypertension complicated with diabetes mellitus,their health risks are not a simple sum but present complex interactive effects.Clarifying the clinical characteristics of such patients is t...Objective:For patients with hypertension complicated with diabetes mellitus,their health risks are not a simple sum but present complex interactive effects.Clarifying the clinical characteristics of such patients is the key to solving this medical problem.Methods:From June 2023 to June 2024,this study conducted a comparative study on 100 patients with hypertension complicated with diabetes mellitus and 100 patients with hypertension alone.By retrospectively analyzing clinical data of patients,the differences in disease manifestations,complication occurrence,and treatment effects between the two groups were explored in depth,and the unique challenges and treatment difficulties faced by patients with hypertension complicated with diabetes mellitus were identified.Results:Hypertensive patients with concurrent diabetes had more difficult blood glucose and blood pressure control,and were more prone to severe complications such as cardiovascular lesions and renal damage.Conclusion:The clinical characteristics and treatment needs of patients with hypertension complicated with diabetes mellitus are different from those with hypertension alone,and disease management should be more refined and personalized.展开更多
The axial load-bearing capacity of grouted anchorage systems is critical for rock reinforcement and reflects the interactions among system components.Hence,the mechanical response and failure characteristics of the an...The axial load-bearing capacity of grouted anchorage systems is critical for rock reinforcement and reflects the interactions among system components.Hence,the mechanical response and failure characteristics of the anchorage system under axial loading are of vital importance.They serve as the foundation for establishing the mechanical model of the anchorage system and provide significant guidance for the optimization design of bolts and the assessment of anchorage conditions.However,as the most widely used research method,current pullout tests have not paid sufficient attention to simulating actual rock mass stiffness,have not fully revealed the radial mechanical response during the pullout process,and have not clarified the locations and modes of pullout failure.To address these issues,a testing method simulating hard rock stiffness and strength was developed using elasticity and stiffness equivalence theories.Tests revealed three anchorage failure modes under equivalent hard rock stiffness:tooth cutting,sliding,and sliding-tooth cutting composite failure,with the composite failure being dominant.The pullout load-displacement curves exhibited bimodal patterns for composite failure and single peaks for tooth cutting and sliding failures.Post-peak softening showed up-convex curves for tooth cutting and down-concave curves for sliding failure,while bolt yielding displayed distinct plateaus.The radial stress trends at the rock-grout interface paralleled pullout load curves,with sliding failure exhibiting approximately 10 MPa lower peak radial stress compared to tooth cutting failure.Anchorage length most strongly affected peak load,while grout properties predominantly governed failure mode.展开更多
Understanding the bubble behaviours and flow characteristics of large-capacity bottom-blowing electric arc furnace(EAF)is crucial for potential exogenous gas-induced slag foaming process and enhancement of molten bath...Understanding the bubble behaviours and flow characteristics of large-capacity bottom-blowing electric arc furnace(EAF)is crucial for potential exogenous gas-induced slag foaming process and enhancement of molten bath dynamics.A physical model and a 3D gas-slag-steel transient bottom-blowing numerical model of a 150 t EAF were established to investigate the bubble behaviour and flow characteristics throughout the molten steel bath and slag layer under bottom-blowing,with referring to gas flow rate,plug diameter,plug arrangement and injection angle.Results indicate that the average bubble sizes experience increase,dynamic stability and decrease in molten steel bath and then undergo decrease and increase after entering into slag layer for all bottom-blowing modes.The bubble numbers exhibit the opposing trends during the process.Increase in gas flow rate leads to a significant rise in average bubble size but a decrease in number,average dwelling time and the spread area of bubbles in slag layer.Increase in plug diameter causes an opposite impact.The effect of plug arrangement radii on bubbles is almost negligible.Increasing the injection angle results in an increase in bubble size and a decrease in both bubble number and dwelling time in slag layer.The slag foaming potential was discussed referring to the bubble size,number and dwelling time in slag layer.Increase in gas flow rate and plug diameters can significantly enhance the fluids flow through increasing average flow velocity,decreasing mixing time and dead zone ratio of molten bath.Plug arrangement radius and injection angle express nonlinear correlation with average flow velocity and dead zone ratio,and the plug arrangement radius of 0.5R(R represents the radius of bottom circle of EAF model)and injection angle of 15°perform better in enhancing dynamics of molten bath.A group of bottom-blowing parameters are proposed to achieve better comprehensive performance of bubble-induced slag foaming and molten bath dynamics.展开更多
Major chemical ionic components in water serve as indicators of natural factors in the areas traversed by water bodies,and are thus widely used to elucidate key hydrogeochemical processes,including rock weathering,aqu...Major chemical ionic components in water serve as indicators of natural factors in the areas traversed by water bodies,and are thus widely used to elucidate key hydrogeochemical processes,including rock weathering,aquatic evaporation-crystallization,and the input of precipitation-derived materials into river basins.A total of 208 water samples were collected between August 2021 and August 2022 to investigate the hydrochemical characteristics and their influencing factors of the surface water and the groundwater in the Mingyong River Basin.To systematically analyze the data,we combined hydrogeochemical and statistical methods:descriptive statistics characterized ion concentration and physicochemical parameter distributions;Piper trilinear diagrams classified hydrochemical types;Pearson correlation analysis assessed ion-ion and ionTDS dependencies;Gibbs diagrams and ion ratio analysis identified solute sources;and the absolute principal component score-multiple linear regression(APCS-MLR)model quantified the contribution rates of different influencing factors.The results revealed that the dominant cations in the surface water and groundwater are Ca^(2+)and Mg^(2+),while the dominant anions are HCO_(3)^(-)and SO_(4)^(2-).The groundwater exhibits an extended residence time within rock strata,facilitating prolonged interaction with soluble minerals and intensifying the water-rock reaction process,thereby resulting in higher levels of electrical conductivity(EC),pH,and total dissolved solids(TDS)than those in the surface water.Secondly,the parameters of the surface water and groundwater indicate positive correlation.The weathering of rocks constitutes the primary solute source in the water of the basin.The hydrochemical composition of the basin water is primarily influenced by both carbonate and silicate rocks,with a minor contribution from evaporite rocks.The water bodies in the basin are affected by anthropogenic activities.The surface water is influenced by four sources,namely lixiviation-enrich,human activities,geological environmental,and unknown sources.The groundwater is influenced by five sources,namely lixiviation-enrich,primary geological,human activities,geological environmental,and unknown sources.展开更多
Clarifying the photosynthetic and population characteristics of conventional japonica rice at different yield levels is crucial for boosting yield and ensuring food security.Therefore,a two-year field trial with two c...Clarifying the photosynthetic and population characteristics of conventional japonica rice at different yield levels is crucial for boosting yield and ensuring food security.Therefore,a two-year field trial with two conventional japonica varieties was conducted at four planting densities:16 cm×30 cm(D1),14 cm×30 cm(D2),12 cm×30 cm(D3),and 10 cm×30 cm(D4).This study aimed to investigate how photosynthetic and population characteristics influence grain yield under varying planting densities.The results indicated that higher yields were primarily driven by increased grain weight and seed-setting rate(with a 9.68%‒11.40%higher single panicle weight),supported by optimized dry matter translocation and source-sink relationships.Elevated planting density(D2‒D4)enhanced panicle number and total spikelet number(by 3.91%‒15.00%)but reduced the number of spikelets per panicle,1000-grain weight,and photosynthetic efficiency due to mutual shading.Despite these trade-offs,yield increased by 4.10%‒12.42%under higher densities.The use of planting density D4 in japonica rice cultivation contributed to maximize yield.These findings provide important theoretical insights and practical significance for increasing the yield of conventional japonica rice and ensuring food security.展开更多
Taking half-tube part with curvature as an example,the Impact Hydroforming(IHF)characteristics were studied by combining the actual forming experiment and numerical simulation.The IHF experiment showed that wrinkles a...Taking half-tube part with curvature as an example,the Impact Hydroforming(IHF)characteristics were studied by combining the actual forming experiment and numerical simulation.The IHF experiment showed that wrinkles appeared at the bottom of the part during single-step forming,but no wrinkles were observed during double-step forming.The thinning rate and deviation of the wall thickness of the part in each area were less than 20%and 2.7 mm,correspondingly,and the drawing depth of the part reached 45.8 mm.The effect of double-step forming was better than that of single-step forming,which was related to the IHF forming law.Besides,the characteristics of the IHF process were studied by numerical simulation.The results indicated that when double-step forming was utilized,there was almost no velocity field in the opposite direction of deformation after the bottom of the part contacted the die,and the existence of stress state at the bottom would restrain and eliminate the wrinkles.The inertia effect evolved with the driving pressure.Specially,the inertia effect can improve the flow of metal and reduce the deviation of the wall thickness of the part under double-step forming.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.52364004 and 52264006)The Youth Talent Growth Project of Guizhou Provincial Department of Education(Grant No.QianJiaoJi[2024]18).
文摘Extensive engineering experience and research findings suggest that rock mass instability is typically attributed to human engineering activities and natural disturbances,resulting in general dynamic mechanical properties.This is attributed to external interference resulting from the extensive use of the mechanical and blasting techniques necessary for mineral extraction.Quantifying the impact of dynamic disturbances on rock deformation behavior is essential for comprehending the long-term response of surrounding rock during excavation.This study placed the rock to sustained pressure and investigated the impact of varying hammer heights and dry and wet(W-D)damage on its shear failure behavior.This study investigated the fatigue disturbance studies on W-D damaged sandstone samples via W-D equipment,a disturbance creep device,digital image correlation(DIC),and acoustic emission(AE)technology.The experimental findings suggest that acoustic emission sensors can be utilized to quantify the internal damage of rock samples during cyclic impact,whereas DIC technology(optical measurement)is capable of capturing the surface crack propagation of samples.Under repeated impact and the combined action of W-D conditions,the bearing capacity of sandstone decreases,whereas the deformation capacity increases.Furthermore,the W-D cycles and impact strength are inversely related to the fatigue life.The intensity of W-D damage and disturbances further accelerates the development and propagation of cracks under cyclic disturbances.The research results are of preventive significance to ensure the safety and sustainable development of engineering construction.
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3701000)the National Natural Science Foundation of China(Nos.52471118,52101125,U2037601,and U21A2048)Young Elite Scientists Sponsorship Program by CAST,China(No.2022QNRC001)。
文摘The dependence of shrinkage porosities on microstructure characteristics of Mg−12Al alloy was investigated.The distribution,morphology,size,and number density of shrinkage porosities were analyzed under different cooling rates.The relationship between shrinkage porosities and microstructure characteristics was discussed in terms of temperature conditions,feeding channel characteristics,and feeding capacity.Further,the feeding behavior of the residual liquid phase in the solid skeleton was quantified by introducing permeability.Results show a strong correlation between the solid microstructure skeleton and shrinkage porosity characteristics.An increase in permeability corresponds to a declining number density of shrinkage porosities.This study aims to provide a more complete understanding how to reduce shrinkage porosities by controlling microstructure characteristics.
基金The Central Government Guides Local Foundation for Science and Technology Development(Grant No.YDZJSX2024B004).
文摘The soft actuator is characterized by high safety,flexibility,and adaptability.It is capable of both active and passive defor-mations.This paper presents a discrete degree of freedom(DOF)method for soft actuators to reveal DOF characteristics.The method draws on the superposition mechanism of the deformation characteristics of the sarcomere in the skeletal muscles of living organisms.Firstly,the multi-DOF deformation characteristics of the soft actuator are discretized into superimposed combinations of single-DOF micro-units.Then,the soft actuator was determined to contain deformation characteristics such as extension-contraction,bending,and twisting.Eighteen types of micro-units with basic deforma-tion characteristics were obtained depending on the axis and orientation.Further,the mapping relationship between the combination of micro-units and the motion characteristics of the soft actuator based on the GF set theory was established.Finally,an active-passive DOF co-structured soft actuator(APCSA)was developed.The graphical approach analyzes the experimental results,and it can be concluded that active and passive DOFs can coexist in the composite deformation of the soft actuator.
文摘Standardization is necessary for the early industrialization of the new materials and technology.It is achieved by having agreed practices for the measurement of properties and other characteristics.The promising use of graphene-based materials in fields like electronics,energy,and composites has resulted in standards for their nomenclature,the measurement of key characteristics,and their specification,etc.Among these,standards for measuring the key characteristics are crucial.The critical parameters are the number of layers,the type and concentration of defects and functional groups,elemental composition,sheet resistance,and carrier mobility.Standards for characterizing these have been analyzed by the International Organization for Standardization Technical Committee in ISO/TC229 and the International Electrotechnical Commission Technical Committee in IEC/TC113.These give details of applicable or preferred samples,the fundamental principles of the techniques,specific precautions,and points for attention in the relevant standards.The pivotal role of the ISO/TC229 and IEC/TC113 standards is considered and challenges and future trends are outlined.
文摘39 soil samples surrounding a lead-zinc mining area in Guangxi were collected,and the contents of Pb,Hg,Cd,Cr,As,Cu,Zn,and Ni were determined to investigate the pollution characteristics and sources of heavy metals.ArcGIS inverse distance weight difference method was used to analyze the characteristics of pollution distribution,and single-factor pollution index,Nemerow comprehensive pollution index,ground accumulation index,and potential ecological risk index were selected to evaluate the characteristics of heavy metal pollution.Based on correlation analysis,the absolute principal component-multiple linear regression(APCS-MLR)and positive definite matrix factorization(PMF)models were used to analyze the sources of soil heavy metals.The results showed that the average concentrations of all eight heavy metals exceeded both national and Guangxi soil background values.Hg,Cd,and Zn exhibited high variation(greater than 0.5),indicating significant external disturbances,and their spatial distribution was closely related to mining activity locations.The single-factor pollution index evaluation indicated varying degrees of pollution risk for Cd,Zn,and As,with Cd and Zn being the most severe pollutants,as 69.23%and 30.77%of the samples fell into the moderate pollution or higher category.The geoaccumulation index analysis ranked the mean pollution levels of the eight elements as follows:Zn>Cd>Ni>Pb>Cu>Cr>Hg>As,with Cd and Zn showing the most severe contamination,and 51.28%of the samples exhibiting moderate or higher pollution levels.The Nemerow comprehensive pollution index evaluation showed that 74.35%of soil samples were classified as moderate to heavy pollution.The potential ecological risk index assessment indicated significant ecological risks posed by Cd and Zn,with 82.05%and 5.12%of the samples classified as causing strong to extreme ecological risks,respectively.The source apportionment analysis revealed minor differences between the two models.The APCS-MLR model identified three pollution sources and their contribution rates:anthropogenic mining sources(31.13%),parent material sources(40.38%),and unidentified sources(28.49%).The PMF model identified three pollution sources with contribution rates of anthropogenic mining sources(26.10%),parent material sources(46.96%),and a combined traffic and agricultural source(26.61%).Pb,Hg,Cd,and Zn mainly originated from mining activities;Cr,As,and Ni were primarily derived from the parent material,while Cu was predominantly attributed to traffic and agricultural sources.These findings provide a scientific basis for the prevention and control of heavy metal pollution in mining areas.
文摘This paper studies the structural response of high-speed train wipers under the combined action of complex flow fields and scraping actions.The stress concentration areas are determined through simulation analysis,and the stress and aerodynamic load measurement points are reasonably arranged accordingly.The actual measurement is carried out in combination with the operating conditions of the existing lines.The stress variations and spectral characteristics of the train under different speed levels(80,160,180,200 km/h),tunnel entry and exit,and scraper action conditions were compared and analyzed.The stress amplification factors under tunnel intersection and scraper action were obtained,providing boundary conditions for the design of wipers for highspeed s.The research results show that the maximum stress of the wiper structure obtained through simulation calculation is concentrated at the connection of the wiper arm.Structural stress increases with the rise of speed grade.The stress increases by 1.11 times when the tunnel meets.When the scraper operates,the stress on the scraper arm increases by 4.1–7.6 times.Due to the broadband excitation effect of the aerodynamic load,the spectral energy of the structure is relatively high at the natural frequency,which excites the natural mode of the wiper.
基金supported by the Fundamental Research Funds for the Central Universities(No.B250201286)the Jiangsu-Czech Bilateral Co-Funding R&D Project(No.BZ2023011)+2 种基金the Jiangsu School-Enterprise Cooperation R&D Project(No.24880047-D01-001)the Anhui International Joint Research Center of Data Diagnosis and Smart Maintenance on Bridge Structures(No.2021AHGHZD03)the Key Research Project of Natural Science in Colleges and Universities of Anhui Province(No.2024AH051404).
文摘As vital hydraulic infrastructures,concrete dams demand uncompromising safety assurance.Seismic effect commonly serves as a potential factor contributing to the damage of concrete dams,making seismic performance analysis crucial for structural integrity.Numerical simulation based on damage mechanics is usually considered as the approach for investigating the seismic damage behavior of concrete dams.To address the limitations of existing studies and extract the key dynamic characteristics of concrete arch dams,a concrete elastoplastic damage mechanics model is adopted,a seismic load input technique involving the viscoelastic boundary along with equivalent nodal forces is generated,and a spring-contact pair simulation technique formodeling the transverse joints of arch dams is developed.The damage process of an arch dam under the classic Koyna seismic load is simulated,with the damage evolution process under seismic action being characterized.The middle sections of the arch dam near the upper portion are considered regions prone to damage under seismic action.Furthermore,the nonlinear dynamic characteristics caused by the opening and closing collision between transverse joints of the arch damunder strong seismic action are extracted.The extracted dynamic characteristic provides a manifestation for the dynamic damage diagnosis of arch dams based on seismic responses.
基金National Natural Science Foundation of China under Grant No.52278340Natural Science Foundation of Hebei Province under Grant No.E2023202028。
文摘In this study,the dynamic characteristics and microstructures of lacustrine soft clays were studied.Dynamic character tests were conducted on undisturbed,remolded,and saturated lacustrine soft clays,using a dynamic triaxial tester.A scanning electron microscope(SEM)was employed to assess the soil samples after dynamic testing.The results indicate that the dynamic characteristics of lacustrine soft clay were significantly affected by confining pressure and water content.A quantitative relationship was established among confining pressures,water content,and the dynamic shear modulus ratio.The dynamic characteristic parameters of undisturbed,remolded and saturated soil are obviously different,and the original structure can enhance the shear strength of soil.By comparing the results with those from other studies,we found that the dynamic characters of soft clays were considerably varied in different regions,and lacustrine soft clays had a larger dynamic shear modulus ratio and a smaller damping ratio when the dynamic shear strain was large.Using IPP software to process the microstructural images,we found that the soil was dominated by small pores and medium particles,and the roundness of pores and particles had an apparently positive correlation with the maximum diameter.Moreover,the pores and particles of the soil showed fractal characteristics and directionality,and the fractal dimensions and probability entropy were strongly correlated with the macrostructural parameters.Finally,we developed a prediction model for macrostructural and microstructural parameters.
文摘In response to the Ministry of Education’s requirements for building distinctive model software schools,Software College of Northeastern University and Shenzhen Kingdom Technology Co.,Ltd.jointly developed the specialized course“Application and Practice of RPA Technology in FinTech”.Addressing pain points in financial digital transformation,the course integrates robotic process automation(RPA)principles,financial domain knowledge,and RPA platform practice into a“technology-scenario-capability”trinity teaching system.Through 64 credit hours of integrated theory and practice,it covers RPA fundamentals,financial applications,RPA operations(including core skills like Web/desktop automation),and AI integration,cultivating students’ability to design and implement automated financial workflows.It innovatively features a RPA simulation platform,30+financial case studies,and modular task resources,creating a“teacher-machine-student”interactive model.Practice demonstrates the course effectively enhances students’integration of technical application and business acumen,providing a scalable paradigm for cultivating interdisciplinary FinTech talent.
基金supported by the National Key Research and Development Program of China (No.2023YFC3708005)the National Natural Science Foundation of China (Nos.21872102,22172080)the Fundamental Research Funds for the Central Universities (Nankai University,No.63241208)。
文摘Groundwater is a key part of the terrestrial ecosystem,but it is vulnerable to pollution in the context of chemical industry development.Treating contaminated groundwater is challenging due to its stable water quality,hidden contamination,and complex treatment requirements.Current research focuses on advanced treatment technologies,among which the advanced oxidation process(AOPs) of peroxomonosulfate(PMS) has great potential.Although there are many reviews of PMS-based AOP,most of them focus on surface water.This review aims to explore the activation reaction of PMS to groundwater by in-situ chemical oxidation(ISCO) technology,further study the reaction mechanism,compare the treatment effect of characteristic pollutants in the groundwater of the chemical industry park,propose new activation methods and catalyst selection,and provide guidance for future groundwater treatment research.
基金National Natural Science Foundation of China,Grant/Award Numbers:12072363,12372373,51934007,52104234,52174091。
文摘The coal dynamic characteristic stress identification under dynamic load is important for guiding underground mineral mining and predicting underground dynamic disasters.In this article,the dynamic compression test of anthracite under five strain rates is carried out,the evolution law of three kinds of crack characteristic stress is analyzed,and a prediction model of the crack characteristic stress threshold considering the strain rate effect is established.Then,the rationality of crack characteristic stress under dynamic loading is discussed from the damage evolution standpoint,and the crack extension response mechanism during dynamic compression of anthracite is discussed.The result shows that the crack characteristic stress threshold is significantly influenced by the strain rate.The three characteristic stress thresholds are positively correlated with the strain rate,but the ratios to the crest stress gradually decrease.The increase in the strain rate strongly contributes to the crack extension behavior of anthracite.In the crack unstable extension phase,because of the increase of the strain rate,anthracite shows more energy dissipation under the same deformation in association with the stress concentration effect and the dynamic strength enhancement effect.The crack propagation rate is increased,the crack propagation path of the section is more complex,and more severe damage occurs before the dynamic failure of anthracite,which leads to even more severe damage.
文摘The respiratory-circulatory system, including organs such as the nose, pharynx, larynx, trachea, bronchi, and heart, is an organic community responsible for ventilation and gas exchange. The integrity of its anatomical structure directly affects the evolution of pathological processes, and the analysis of their correlation is a core entry point for clinical disease diagnosis, treatment, and mechanism research. Based on this, this paper mainly explores the correlation between the anatomical and pathological characteristics of the respiratory-circulatory system, aiming to provide anatomical and pathological theoretical support for clinical accurate diagnosis, targeted therapy, and prognosis evaluation.
文摘Aiming at the problem of innovative talent training in the industry field in characteristic software colleges,combined with the actual situation of Software College of Northeastern University,this paper analyzes the construction requirements of characteristic talent training mode and training scheme,puts forward the reform of characteristic software innovative talent training scheme integrating production and education,and takes the characteristic direction of financial technology as an example to introduce the curriculum construction based on industry-education integration and school-enterprise cooperation.
基金support from the National Key R&D Program of China(Grant Nos.2023YFB3709900 and 2023YFB3709903)the National Natural Science Foundation of China(Grant Nos.52174293 and U22A20171)+1 种基金the High Steel Center(HSC)at North China University of TechnologyUniversity of Science and Technology Beijing(USTB).
文摘MgO has been shown to facilitate the precipitation of MgO-rich crystalline phases within the MgO-CaO-Al_(2)O_(3)-SiO_(2)(MCAS)glassy inclusion system,which possesses a high liquidus temperature and a significant Young’s modulus.The underlying linkage between the structural evolution and the crystallization characteristics of the MCAS system was systematically investigated using molecular dynamics simulation and thermodynamic calculation.The results revealed that Mg^(2+) ions played a dual role,constructing networks through the formation of tricluster oxygens while consuming bridging oxygens(BOs)in a mechanism similar to Ca^(2+) ions.However,despite this dual role,the network connectivity was still decreased with the increase in MgO/(MgO+Al_(2)O_(3))(M/(M+A))and CaO/(CaO+SiO_(2))(C/(C+S))ratios,primarily due to the reduction in BOs.This microscopic structural evolution resulted in a reduction in viscosity and an enhancement of crystallization ability.Furthermore,the remarkable diffusion capability of Mg^(2+) ions,coupled with the increased proportion of 6-coordinated Mg^(2+)ions,unveiled the mechanism underlying the precipitation of MgSiO_(3) and Mg_(2)SiO_(4) crystals,which exhibited high Young’s moduli of 165.23 and 196.67 GPa,respectively.To prevent the precipitation of MgO-rich crystalline phases,it was crucial to maintain the M/(M+A)ratio below 0.42 and the C/(C+S)ratio below 0.16 within the MCAS system.
文摘Objective:For patients with hypertension complicated with diabetes mellitus,their health risks are not a simple sum but present complex interactive effects.Clarifying the clinical characteristics of such patients is the key to solving this medical problem.Methods:From June 2023 to June 2024,this study conducted a comparative study on 100 patients with hypertension complicated with diabetes mellitus and 100 patients with hypertension alone.By retrospectively analyzing clinical data of patients,the differences in disease manifestations,complication occurrence,and treatment effects between the two groups were explored in depth,and the unique challenges and treatment difficulties faced by patients with hypertension complicated with diabetes mellitus were identified.Results:Hypertensive patients with concurrent diabetes had more difficult blood glucose and blood pressure control,and were more prone to severe complications such as cardiovascular lesions and renal damage.Conclusion:The clinical characteristics and treatment needs of patients with hypertension complicated with diabetes mellitus are different from those with hypertension alone,and disease management should be more refined and personalized.
基金supported by the National Natural Science Foundation of China(Grant No.52279116)the Key Projects of the Yalong River Joint Fund of the National Natural Science Foundation of China(Grant No.U1865203).
文摘The axial load-bearing capacity of grouted anchorage systems is critical for rock reinforcement and reflects the interactions among system components.Hence,the mechanical response and failure characteristics of the anchorage system under axial loading are of vital importance.They serve as the foundation for establishing the mechanical model of the anchorage system and provide significant guidance for the optimization design of bolts and the assessment of anchorage conditions.However,as the most widely used research method,current pullout tests have not paid sufficient attention to simulating actual rock mass stiffness,have not fully revealed the radial mechanical response during the pullout process,and have not clarified the locations and modes of pullout failure.To address these issues,a testing method simulating hard rock stiffness and strength was developed using elasticity and stiffness equivalence theories.Tests revealed three anchorage failure modes under equivalent hard rock stiffness:tooth cutting,sliding,and sliding-tooth cutting composite failure,with the composite failure being dominant.The pullout load-displacement curves exhibited bimodal patterns for composite failure and single peaks for tooth cutting and sliding failures.Post-peak softening showed up-convex curves for tooth cutting and down-concave curves for sliding failure,while bolt yielding displayed distinct plateaus.The radial stress trends at the rock-grout interface paralleled pullout load curves,with sliding failure exhibiting approximately 10 MPa lower peak radial stress compared to tooth cutting failure.Anchorage length most strongly affected peak load,while grout properties predominantly governed failure mode.
基金supported by the National Natural Science Foundation of China(Grant No.52374317).
文摘Understanding the bubble behaviours and flow characteristics of large-capacity bottom-blowing electric arc furnace(EAF)is crucial for potential exogenous gas-induced slag foaming process and enhancement of molten bath dynamics.A physical model and a 3D gas-slag-steel transient bottom-blowing numerical model of a 150 t EAF were established to investigate the bubble behaviour and flow characteristics throughout the molten steel bath and slag layer under bottom-blowing,with referring to gas flow rate,plug diameter,plug arrangement and injection angle.Results indicate that the average bubble sizes experience increase,dynamic stability and decrease in molten steel bath and then undergo decrease and increase after entering into slag layer for all bottom-blowing modes.The bubble numbers exhibit the opposing trends during the process.Increase in gas flow rate leads to a significant rise in average bubble size but a decrease in number,average dwelling time and the spread area of bubbles in slag layer.Increase in plug diameter causes an opposite impact.The effect of plug arrangement radii on bubbles is almost negligible.Increasing the injection angle results in an increase in bubble size and a decrease in both bubble number and dwelling time in slag layer.The slag foaming potential was discussed referring to the bubble size,number and dwelling time in slag layer.Increase in gas flow rate and plug diameters can significantly enhance the fluids flow through increasing average flow velocity,decreasing mixing time and dead zone ratio of molten bath.Plug arrangement radius and injection angle express nonlinear correlation with average flow velocity and dead zone ratio,and the plug arrangement radius of 0.5R(R represents the radius of bottom circle of EAF model)and injection angle of 15°perform better in enhancing dynamics of molten bath.A group of bottom-blowing parameters are proposed to achieve better comprehensive performance of bubble-induced slag foaming and molten bath dynamics.
基金funded by the National Natural Science Foundation of China(No.42061012)the Open Project of Yunnan Province’s First Class Discipline of Soil and Water Conservation and Desertification Control(SBK20240019)。
文摘Major chemical ionic components in water serve as indicators of natural factors in the areas traversed by water bodies,and are thus widely used to elucidate key hydrogeochemical processes,including rock weathering,aquatic evaporation-crystallization,and the input of precipitation-derived materials into river basins.A total of 208 water samples were collected between August 2021 and August 2022 to investigate the hydrochemical characteristics and their influencing factors of the surface water and the groundwater in the Mingyong River Basin.To systematically analyze the data,we combined hydrogeochemical and statistical methods:descriptive statistics characterized ion concentration and physicochemical parameter distributions;Piper trilinear diagrams classified hydrochemical types;Pearson correlation analysis assessed ion-ion and ionTDS dependencies;Gibbs diagrams and ion ratio analysis identified solute sources;and the absolute principal component score-multiple linear regression(APCS-MLR)model quantified the contribution rates of different influencing factors.The results revealed that the dominant cations in the surface water and groundwater are Ca^(2+)and Mg^(2+),while the dominant anions are HCO_(3)^(-)and SO_(4)^(2-).The groundwater exhibits an extended residence time within rock strata,facilitating prolonged interaction with soluble minerals and intensifying the water-rock reaction process,thereby resulting in higher levels of electrical conductivity(EC),pH,and total dissolved solids(TDS)than those in the surface water.Secondly,the parameters of the surface water and groundwater indicate positive correlation.The weathering of rocks constitutes the primary solute source in the water of the basin.The hydrochemical composition of the basin water is primarily influenced by both carbonate and silicate rocks,with a minor contribution from evaporite rocks.The water bodies in the basin are affected by anthropogenic activities.The surface water is influenced by four sources,namely lixiviation-enrich,human activities,geological environmental,and unknown sources.The groundwater is influenced by five sources,namely lixiviation-enrich,primary geological,human activities,geological environmental,and unknown sources.
基金funded by the National Key R&D Program of China (Grant No. 2024YFD2300301)the National Natural Science Foundation of China (Grant Nos. 32472223 and 31901447)+1 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Qinglan Project of Jiangsu Province, China
文摘Clarifying the photosynthetic and population characteristics of conventional japonica rice at different yield levels is crucial for boosting yield and ensuring food security.Therefore,a two-year field trial with two conventional japonica varieties was conducted at four planting densities:16 cm×30 cm(D1),14 cm×30 cm(D2),12 cm×30 cm(D3),and 10 cm×30 cm(D4).This study aimed to investigate how photosynthetic and population characteristics influence grain yield under varying planting densities.The results indicated that higher yields were primarily driven by increased grain weight and seed-setting rate(with a 9.68%‒11.40%higher single panicle weight),supported by optimized dry matter translocation and source-sink relationships.Elevated planting density(D2‒D4)enhanced panicle number and total spikelet number(by 3.91%‒15.00%)but reduced the number of spikelets per panicle,1000-grain weight,and photosynthetic efficiency due to mutual shading.Despite these trade-offs,yield increased by 4.10%‒12.42%under higher densities.The use of planting density D4 in japonica rice cultivation contributed to maximize yield.These findings provide important theoretical insights and practical significance for increasing the yield of conventional japonica rice and ensuring food security.
基金financially supported by the National Key R&D Program of China(No.2024YFE0108800/T24KITG014)the National Natural Science Foundation of China(No:52475411)the International Partnership Program of Chinese Academy of Sciences(No.172GJHZ2022096FN)。
文摘Taking half-tube part with curvature as an example,the Impact Hydroforming(IHF)characteristics were studied by combining the actual forming experiment and numerical simulation.The IHF experiment showed that wrinkles appeared at the bottom of the part during single-step forming,but no wrinkles were observed during double-step forming.The thinning rate and deviation of the wall thickness of the part in each area were less than 20%and 2.7 mm,correspondingly,and the drawing depth of the part reached 45.8 mm.The effect of double-step forming was better than that of single-step forming,which was related to the IHF forming law.Besides,the characteristics of the IHF process were studied by numerical simulation.The results indicated that when double-step forming was utilized,there was almost no velocity field in the opposite direction of deformation after the bottom of the part contacted the die,and the existence of stress state at the bottom would restrain and eliminate the wrinkles.The inertia effect evolved with the driving pressure.Specially,the inertia effect can improve the flow of metal and reduce the deviation of the wall thickness of the part under double-step forming.
