Solidification cracking(SC)of 2024 high-strength aluminium alloy during fusion welding or additive manufacturing has been a long-term issue.In this work,crack-free weld could be obtained using a Zr-core-Alshell wire(Z...Solidification cracking(SC)of 2024 high-strength aluminium alloy during fusion welding or additive manufacturing has been a long-term issue.In this work,crack-free weld could be obtained using a Zr-core-Alshell wire(ZCASW filler material,a novel filler)coupled with an oscillating laser-arc hybrid welding process,and we investigated the solidification cracking susceptibility(SCS)and cracking behavior of AA2024 weld fabricated with different filler materials.The cracking inhibition mechanism of the weld fabricated with ZCASW filler material was elucidated by combined experiments and phase-field simulation.The results show that the effectiveness of filler materials in reducing the SC gradually improves in the order of ER2319 filler material<ER4043 filler material<ZCASW filler material.The main cracking(when using the ER2319 filler material)branches and the micro cracking branches interact with each other to produce cracking coalescence,which aggravates the cracking propagation.The formation of the Al_(3) Zr phase(when using the ZCASW filler material)promotes heterogeneous nucleation of α-Al,thereby resulting in finer and equiaxed non-dendrite structures,which shortens the liquid phase channels and decreases cracking susceptibility index|d T/d(f_(s))^(1/2)|(T is temperature and f_(s) is solidification fraction)at final solidification.A higher proportion(7.65%area fraction)of inter-dendrite phase with spherical distribution state,a shorter(8.6 mm liquid channel length)inter-dendrite phase coupled with round non-dendrite structure(6μm dendrite size)effectively inhibit the SC.The present study can be a useful database for welding and additive manufacturing of AA2024.展开更多
Peridynamics(PD)is an effective method for simulating the spontaneous initiation and propagation of tensile cracks in materials.However,it faces great challenges in simulating compression-shear cracking of geomaterial...Peridynamics(PD)is an effective method for simulating the spontaneous initiation and propagation of tensile cracks in materials.However,it faces great challenges in simulating compression-shear cracking of geomaterials due to the lack of efficient contact-friction models.This paper introduces an original contact-friction model that leverages twin mesh and potential function principles within PD to model rock cracking under tensile and compressive stresses.The contact detection algorithm,based on space segmentation axis-aligned bounding box(AABB)tree data structure,is used to address the significant challenge of highly efficient contact detection in compression and shear problems.In this method,the twin mesh and potential function are utilized to quantify contact detection and contact degree,as well as friction behavior.This is in contrast to the distance and circular contact area model,which lacks physical significance in the classical PD method.As demonstrated by the tests on specimens containing cracks,the proposed model can capture 8 types of secondary fractures,reduce the contact detection error by about 29%e56%,and increase the contact retrieval efficiency by over 1600 times compared to the classic PD models.This significantly enhances the capability of PD to simulate the initiation,expansion,and coalescence of intricate compression-shear cracks.展开更多
Soil desiccation cracking is a common phenomenon on the earth surface.Numerical modeling is an effective approach to study the desiccation cracking mechanism of soil.This work develops a novel 3D moisture diffusion di...Soil desiccation cracking is a common phenomenon on the earth surface.Numerical modeling is an effective approach to study the desiccation cracking mechanism of soil.This work develops a novel 3D moisture diffusion discrete model that is capable of dynamically assessing the effect of cracking on moisture diffusion and allowing moisture to be discontinuous on both sides of the cracks.Then,the parametric analysis of the moisture exchange coefficient in the 3D moisture diffusion discrete model is carried out for moisture diffusion in continuous media,and the selection criterion of the moisture exchange coefficient for the unbroken cohesive element is given.Subsequently,an example of moisture migration in a medium with one crack is provided to illustrate the crack hindering effect on moisture migration.Finally,combining the 3D moisture diffusion discrete model with the finite-discrete element method(FDEM),the moisture diffusion-fracture coupling model is built to study the desiccation cracking in a strip soil and the crack pattern of a rectangular soil.The evolution of crack area and volume with moisture content is quantitatively analyzed.The modeling number and average width of cracks in the strip soil show a good consistency with the experimental results,and the crack pattern of the rectangular soil matches well with the existing numerical results,validating the coupled moisture diffusion-fracture model.Additionally,the parametric study of soil desiccation cracking is performed.The developed model offers a powerful tool for exploring soil desiccation cracking.展开更多
Additive manufacturing (AM) of high-strength metallic alloys frequently encounters detrimental distortion and cracking, attributed to the accumulation of thermal stresses. These issues significantly impede the practic...Additive manufacturing (AM) of high-strength metallic alloys frequently encounters detrimental distortion and cracking, attributed to the accumulation of thermal stresses. These issues significantly impede the practical application of as-printed components. This study examines the Mg-15Gd-1Zn-0.4Zr (GZ151K, wt.%) alloy, a prototypical high-strength casting Mg-RE alloy, fabricated through laser powder bed fusion (LPBF). Despite achieving ultra-high strength, the GZ151K alloy concurrently exhibits a pronounced cold-cracking susceptibility. The as-printed GZ151K alloy consists of almost fully fine equiaxed grains with an average grain size of merely 2.87 µm. Subsequent direct aging (T5) heat treatment induces the formation of dense prismatic β' precipitates. Consequently, the LPBF-T5 GZ151K alloy manifests an ultra-high yield strength of 405 MPa, surpassing all previously reported yield strengths for Mg alloys fabricated via LPBF and even exceeding that of its extrusion-T5 counterpart. Interestingly, as-printed GZ151K samples with a build height of 2 mm exhibit no cracking, whereas samples with build heights ranging from 4 to 18 mm demonstrate severe cold cracking. Thermal stress simulation also suggests that the cold cracking susceptibility increases significantly with increasing build height. The combination of high thermal stress and low ductility in the as-printed GZ151K alloy culminates in a high cold cracking susceptibility. This study offers novel insights into the intricate issue of cold cracking in the LPBF process of high-strength Mg alloys, highlighting the critical balance between achieving high strength and mitigating cold cracking susceptibility.展开更多
Mg-Li alloys hold significant potential for applications in aerospace,automotive manufacturing,military weaponry,and biomedical implants,due to their excellent recyclability,high specific strength,biocompatibility,and...Mg-Li alloys hold significant potential for applications in aerospace,automotive manufacturing,military weaponry,and biomedical implants,due to their excellent recyclability,high specific strength,biocompatibility,and superior electromagnetic shielding properties.However,their poor corrosion resistance and high susceptibility to environmentally assisted cracking(EAC)significantly limit broader application.In recent years,growing attention has been directed toward understanding the corrosion and EAC behavior of Mg-Li alloys,as localized corrosion areas and hydrogen generated during the corrosion process can serve as crack initiation points and promote crack propagation.A comprehensive understanding of these mechanisms is essential for enhancing the reliability and performance of Mg-Li alloys in practical environments.This paper presents a detailed review of corrosion and EAC in Mg-Li alloys,focusing on corrosion behavior,crack initiation and propagation mechanisms,and the key factors influencing these processes.It summarizes recent advances in alloying,heat treatment,mechanical processing,microstructural control,environmental influences,mechanical loading,and surface treatments.In addition,the paper explores future research directions,highlights emerging trends,and proposes strategies to improve the durability and service performance of Mg-Li alloys.展开更多
A comparative study of products of thermal and thermocatalytic cracking of polypropylene(PP) in the presence of potassium polytitanate(PPT) synthesized by treatment of TiO_(2)(rutile) powder with molten mixture of KOH...A comparative study of products of thermal and thermocatalytic cracking of polypropylene(PP) in the presence of potassium polytitanate(PPT) synthesized by treatment of TiO_(2)(rutile) powder with molten mixture of KOH and KNO_(3) taken in a weight ratio of 30∶30∶40 has been carried out.It was shown that the studied type of PPT powder exhibits catalytic properties in the reaction of thermal decomposition of PP,compared to the effect of commercial zeolite catalyst CBV-780 traditionally used for this purpose.Based on the analysis performed,the differences in the mechanism of catalytic action of PPT and the zeolite were considered.The reasons for the observed differences in the composition of PP cracking products and in the rate of coke formation on the surface of studied catalysts were analyzed.Considering the obtained results,it has been proposed that the CBV-780 catalyst promoted more intensive production of the gaseous hydrocarbons compared to PPT,due to higher specific surface area(internal surface) accessible for relatively light and small-sized hydrocarbon products of cracking.However,intensive coke formation on the outer surface of the microporous zeolite contributes to the blocking of transport channels and the rapid loss of catalytic action.At the same time,PPT,which initially has a smaller specific surface area,retains its catalytic activity significantly longer due to slit-shaped flat pores and higher transport accessibility of the inner surface.展开更多
This study leverages machine learning to perform high-throughput computational screening of n-hexane cracking initiators.Artificial neural networks are applied to predict the chemical performance of initiators,using s...This study leverages machine learning to perform high-throughput computational screening of n-hexane cracking initiators.Artificial neural networks are applied to predict the chemical performance of initiators,using simulated pyrolysis data as the training dataset.Various feature extraction methods are utilized,and five neural network architectures are developed to predict the co-cracking product distribution based on molecular structures.High-throughput screening of 12946 molecules outside the training dataset identifies the top 10 initiators for each target product—ethylene,propylene,and butadiene.The relative error between predicted and simulated values is less than 7%.Additionally,reaction pathway analysis elucidates the mechanisms by which initiators influence the distribution of cracking products.The proposed framework provides a practical and efficient approach for the rapid identification and evaluation of high-performance cracking initiators.展开更多
Fruit cracking is a persistent challenge for table grape growing.To investigate the mechanism of this disorder,a comprehensive two-year investigation was conducted to assess the fruit cracking percentage of 15 table g...Fruit cracking is a persistent challenge for table grape growing.To investigate the mechanism of this disorder,a comprehensive two-year investigation was conducted to assess the fruit cracking percentage of 15 table grape(Vitis vinifera L.)varieties.Based on the findings,the cracking-susceptible variety‘Xiangfei'and the cracking-resistant variety‘Zuijinxiang'were selected for further study.Fruit growth curves for‘Zuijinxiang'and‘Xiangfei'were plotted based on fruit diameter and total soluble solids content,revealing that both varieties exhibited typical double-sigmoidal patterns that were highly similar.The period between 48 and 53 days after full bloom(DAFB)was identified as the critical phase for fruit cracking incidence.Furthermore,during the fruit cracking period,‘Xiangfei'fruit exhibited significantly higher water content and mesocarp cell area compared with those of‘Zuijinxiang'.Applying aquaporin inhibitors(nano-silver)to‘Xiangfei'berries reduced fruit water uptake and cracking percentage,whereas applying aquaporin activators(forskolin)to‘Zuijinxiang'berries increased fruit water uptake and cracking percentage.Additionally,expression analysis of six genes associated with plasma membrane intrinsic proteins(PIPs)synthesis(VvPIP1;1,VvPIP1;2,VvPIP1;3,VvPIP2;1,VvPIP2;2,and VvPIP2;3)revealed that only the expression level of VvPIP1;1 was higher in‘Zuijinxiang'than in‘Xiangfei'during the fruit cracking period,whereas the expression levels of the other genes exhibited no significant difference between the two varieties.Transgenic overexpression of VvPIP1;1 in tomato resulted in increased fruit water content,enlarged mesocarp cell size,and enhanced fruit cracking percentage.These findings indicate that VvPIP1;1 plays a pivotal role in controlling grape berry cracking.展开更多
Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This...Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.展开更多
Soil desiccation cracking is ubiquitous in nature and has significantpotential impacts on the engineering geological properties of soils.Previous studies have extensively examined various factors affecting soil cracki...Soil desiccation cracking is ubiquitous in nature and has significantpotential impacts on the engineering geological properties of soils.Previous studies have extensively examined various factors affecting soil cracking behavior through a numerous small-sample experiments.However,experimental studies alone cannot accurately describe soil cracking behavior.In this study,we firstly propose a modeling framework for predicting the surface crack ratio of soil desiccation cracking based on machine learning and interpretable analysis.The framework utilizes 1040 sets of soil cracking experimental data and employs random forest(RF),extreme gradient boosting(XGBoost),and artificialneural network(ANN)models to predict the surface crack ratio of soil desiccation cracking.To clarify the influenceof input features on soil cracking behavior,feature importance and Shapley additive explanations(SHAP)are applied for interpretability analysis.The results reveal that ensemble methods(RF and XGBoost)provide better predictive performance than the deep learning model(ANN).The feature importance analysis shows that soil desiccation cracking is primarily influencedby initial water content,plasticity index,finalwater content,liquid limit,sand content,clay content and thickness.Moreover,SHAP-based interpretability analysis further explores how soil cracking responds to various input variables.This study provides new insight into the evolution of soil cracking behavior,enhancing the understanding of its physical mechanisms and facilitating the assessment of potential regional development of soil desiccation cracking.展开更多
This study investigates the stress corrosion cracking(SCC)behavior of a Mg-8Gd-3Y-0.5Zr alloy in a 3.5 wt.%NaCl solution using slow strain rate tensile(SSRT)testing.The results reveal that SCC suscepti-bility increase...This study investigates the stress corrosion cracking(SCC)behavior of a Mg-8Gd-3Y-0.5Zr alloy in a 3.5 wt.%NaCl solution using slow strain rate tensile(SSRT)testing.The results reveal that SCC suscepti-bility increases as the strain rate decreases,with hydrogen embrittlement(HE)becoming more dominant at lower strain rates,leading to brittle fracture.Anodic dissolution(AD)plays a more significant role at higher strain rates,resulting in mixed fracture modes.Additionally,the mechanical properties and SCC resistance are strongly influenced by the sample orientation.TD-oriented samples show higher SCC susceptibility than RD-oriented ones due to the alignment of Gd-and Y-rich precipitates and grain boundaries,which act as initiation sites for SCC.These precipitates form micro-galvanic couples with the Mg matrix,accelerating localized corrosion and HE.The findings provide insights into the SCC mechanisms of VW83 alloy and highlight the importance of optimizing microstructure and processing conditions to improve its corrosion resistance.展开更多
A mathematical model coupling flow,solidification,strain-stress,and interface failure was developed.Following identification of crack source type through thermal tensile experiment and validation by strain-stress comp...A mathematical model coupling flow,solidification,strain-stress,and interface failure was developed.Following identification of crack source type through thermal tensile experiment and validation by strain-stress comparison,the model was used to investigate slab cracking tendency near precipitated phases,considering various locations,sizes and shapes of them.The results show that the jet from submerged entry nozzle creates a“double roll”flow pattern during continuous casting,resulting in more uniform temperature distributions at slab corner and wide surface center compared with narrow surface center.Consequently,precipitated phases,particularly those located on the narrow surface,readily induce stress concentration and thus increase cracking tendency.A smaller precipitated phase size can reduce the stress concentration zone,while a more spherical shape can distribute surrounding stress along its surface and lower the internal stress within it,thereby decreasing the risk of slab cracking during continuous casting.The optimal precipitated phase exhibits a spherical or ellipsoidal shape with a major axis of less than 5µm,minimizing its potential to initiate cracks.展开更多
In subtropical regions,soil desiccation cracking often exerts a significant impact on the interactions between soil water and the atmosphere,making it a subject of great interest in the fields of geotechnical and geoe...In subtropical regions,soil desiccation cracking often exerts a significant impact on the interactions between soil water and the atmosphere,making it a subject of great interest in the fields of geotechnical and geoenvironmental engineering.Despite the growing utilization of biochar as a sustainable soil amendment,there remains a lack of in-depth understanding of biocharewateresoil interactions,as well as its impact on soil desiccation cracking behavior.To address this gap,this study investigated the influence and mechanism of woody biochar dosages and particle sizes on the cracking behavior of three typical clayey soils in subtropical regions in China,namely Pukou expansive soil(PKE),Xiashu soil(XS),and Zhongshan lateritic soil(ZSL).The quantitative analysis of crack images revealed that the use of biochar was not consistently effective in preventing soil cracking.The application of biochar reduced the crack ratio in PKE and XS by up to 24.03%and 53.89%,respectively.In contrast,ZSL exhibited a 74.57%increase in crack ratio with the addition of 10%biochar.This influence can be further enhanced by increasing the dosage and reducing the particle size of biochar.The microstructural analysis demonstrated that biochar exerts an inhibitory effect on PKE and XS primarily through direct replacement,direct barrier,and indirect physical mechanisms.Moreover,an indirect chemical effect between biochar and clay particles was proposed to explain the exacerbated cracking observed in biochar-amended ZSL.To effectively utilize biochar for soil cracking mitigation in subtropical regions,it is essential to evaluate the initial mineral composition and cation type of the soil.展开更多
With growing concerns over environmental issues,ethylene manufacturing is shifting from a sole focus on economic benefits to an additional consideration of environmental impacts.The operation of the thermal cracking f...With growing concerns over environmental issues,ethylene manufacturing is shifting from a sole focus on economic benefits to an additional consideration of environmental impacts.The operation of the thermal cracking furnace in ethylene manufacturing determines not only the profitability of an ethylene plant but also the carbon emissions it releases.While multi-objective optimization of the thermal cracking furnace to balance profit with environmental impact is an effective solution to achieve green ethylene man-ufacturing,it carries a high computational demand due to the complex dynamic processes involved.In this work,artificial intelligence(AI)is applied to develop a novel hybrid model based on physically consistent machine learning(PCML).This hybrid model not only reduces the computational demand but also retains the interpretability and scalability of the model.With this hybrid model,the computational demand of the multi-objective dynamic optimization is reduced to 77 s.The optimization results show that dynamically adjusting the operating variables with coke formation can effectively improve profit and reduce CO_(2)emissions.In addition,the results from this study indicate that sacrificing 28.97%of the annual profit can significantly reduce the annual CO_(2)emissions by 42.89%.The key findings of this study highlight the great potential for green ethylene manufacturing based on AI through modeling and optimization approaches.This study will be important for industrial practitioners and policy-makers.展开更多
Implants are inevitably subjected to stress corrosion,bringing serious challenges to the controlled degradation of biomedical Mg alloys.It is worth studying the stress corrosion cracking(SCC)behavior of Mg alloy and e...Implants are inevitably subjected to stress corrosion,bringing serious challenges to the controlled degradation of biomedical Mg alloys.It is worth studying the stress corrosion cracking(SCC)behavior of Mg alloy and exploring Mg alloy with good SCC resistance for wide biomedical applications.In this work,the as-cast and as-extruded Mg-3Gd-1Zn-0.4Zr(GZ31K)alloys with uniform corrosion were used to investigate SCC behavior.The as-extruded GZ31K alloy exhibited better corrosion resistance and mechanical properties than the as-cast one mainly owing to grain refinement and uniformly distributed fine precipitates,and possessed superior SCC resistance.To clarify the SCC mechanism,the slow strain rate tests were assisted with applied constant potentials via an electrochemical workstation.Accelerated anodic dissolution at anodic polarization deteriorated SCC resistance due to the initiation of corrosion pits and micro-cracks.However,cathodic polarization had no obvious effects on SCC resistance,along with both retarded corrosion and accelerated hydrogen evolution.Stacking faults in GZ31K alloy were hydrogen capture containers to reduce the effect of hydrogen on SCC resistance during cathodic polarization.These findings provide new insights into the evaluation of SCC mechanism,and offer more opportunities to explore Mg alloys with good SCC resistance by regulating anodic dissolution.展开更多
The small punch test technique facilitates the convenient acquisition of the mechanical properties of in-service equipment materials and the assessment of their remaining service life through sampling.However,the weld...The small punch test technique facilitates the convenient acquisition of the mechanical properties of in-service equipment materials and the assessment of their remaining service life through sampling.However,the weldability of components with thin walls after small punch sampling,such as ethylene cracking furnace tubes,requires further investigation.Therefore,the weldability of in-service ethylene cracking furnace tubes following small punch sampling was investigated through nondestructive testing,microstructural characterization,and mechanical testing.Additionally,the impact of small punch sampling size and residual stress on the creep performance of the specimens was studied using an improved ductility exhaustion model.The results indicate that both the surface and interior of the weld repair areas on new furnace tubes and service-exposed furnace tubes after small-punch sampling are defect-free,exhibiting good weld quality.The strength of the specimens after weld repair was higher than that before sampling,whereas toughness decreased.Weld repair following small punch sampling of furnace tubes is both feasible and necessary.Furthermore,a linear relationship was observed between specimen thickness,diameter,and creep fracture time.The residual stress of welding affects the creep performance of the specimen under different stresses.展开更多
In this work,a new process for achieving the recovery of elemental sulfur by utilizing a fluidized catalytic cracking(FCC) riser reactor for SOxtreatment(FCC-DeSOx) is proposed.The process leverages the high temperatu...In this work,a new process for achieving the recovery of elemental sulfur by utilizing a fluidized catalytic cracking(FCC) riser reactor for SOxtreatment(FCC-DeSOx) is proposed.The process leverages the high temperatures and hydrocarbon concentrations in the FCC riser reactor to convert SOxinto H_(2)S.Subsequently,H_(2)S,along with the cracked gas,is processed downstream to produce sulfur.Thermodynamic analysis of the key reduction reactions in the FCC-DeSOxprocess revealed that complete conversion of SOxto H_(2)S is feasible in the dry gas(hydrogen-rich) prelift zone,as well as the upper and lower zones of the riser,upon achieving thermodynamic equilibrium.Experimental studies were conducted to replicate the conditions of these reaction zones using a low concentration of hydrogen gas as the reducing agent.Through process optimization,investigation of the minimum reaction time,and kinetic studies,the potential of this method for the complete reduction of SOxwas further confirmed.展开更多
The effect of aging precipitation on the stress corrosion cracking(SCC)mechanism of Ni(Fe,Al)-maraging steel was studied through the comparative characterization and analyses of the microstructures and fracture featur...The effect of aging precipitation on the stress corrosion cracking(SCC)mechanism of Ni(Fe,Al)-maraging steel was studied through the comparative characterization and analyses of the microstructures and fracture features of solid–solution and peak-aged steels.Aging precipitation exerts a chain of impacts on the deformative compatibility and electrochemical difference between the matrix and oth-er phases or interfaces.The strength of the martensite matrix is enhanced by abundant and evenly dispersed Ni(Fe,Al)precipitates,thereby reducing the possibility of splitting across martensite laths.Meanwhile,the Volta potential difference(VPD)between the matrix and primary NbC particles increases from 11.43 to 18.60 mV.Given that most of the primary NbC particles tend to be distributed along high-angle grain boundaries(HAGBs),anodic dissolution along HAGBs accelerates.Therefore,mechanical and electrochemical factors triggered by aging precipitation are involved in the variation in SCC behavior and mechanism.The SCC susceptibility of the steel in-creases along with the increasing tendency for intergranular cracking.展开更多
Coking at the fractionating tower bottom and the decant oil circulation system disrupts the heat balance,leading to unplanned shutdown and destroying the long period stable operation of the Fluid Catalytic Cracking Un...Coking at the fractionating tower bottom and the decant oil circulation system disrupts the heat balance,leading to unplanned shutdown and destroying the long period stable operation of the Fluid Catalytic Cracking Unit(FCCU).The FCCU operates through interconnected subsystems,generating high-dimensional,nonlinear,and non-stationary data characterized by spatiotemporally correlated.The decant oil solid content is the crucial indicator for monitoring catalyst loss from the reactor-regenerator system and coking risk tendency at the fractionating tower bottom that relies on sampling and laboratory testing,which is lagging responsiveness and labor-intensive.Developing the online decant oil solid content soft sensor using industrial data to support operators in conducting predictive maintenance is essential.Therefore,this paper proposes a hybrid deep learning framework for soft sensor development that combines spatiotemporal pattern extraction with interpretability,enabling accurate risk identification in dynamic operational conditions.This framework employs a Filter-Wrapper method for dimensionality reduction,followed by a 2D Convolutional Neural Network(2DCNN)for extracting spatial patterns,and a Bidirectional Gated Recurrent Unit(BiGRU)for capturing long-term temporal dependencies,with an Attention Mechanism(AM)to highlight critical features adaptively.The integration of SHapley Additive exPlanations(SHAP),Complementary Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN),2DCNN,and expert knowledge precisely quantifies feature contributions and decomposes signals,significantly enhancing the practicality of risk identification.Applied to a China refinery with processing capacity of 2.80×10^(6) t/a,the soft sensor achieved the R^(2) value of 0.93 and five-level risk identification accuracy of 96.42%.These results demonstrate the framework's accuracy,robustness,and suitability for complex industrial scenarios,advancing risk visualization and management.展开更多
The destabilization of overhanging rock is a dangerous geological problem.In this study,a generalized model of typical overhanging cliffs from the Three Gorges Reservoir area in China with different fracture angles,fr...The destabilization of overhanging rock is a dangerous geological problem.In this study,a generalized model of typical overhanging cliffs from the Three Gorges Reservoir area in China with different fracture angles,fracture lengths,and free surface depths is constructed to investigate the cracking and deformation behavior of overhanging rocks.Laboratory tests and deformation field monitoring using the digital image correlation(DIC)method are performed on these specimens to reproduce the destabilization and failure process of overhanging rock under external loading.The influence of peak load is found to be the most sensitive to the fracture length,followed by the free surface depth,and to be the least sensitive to the fracture angle.The DIC-based strain fields reveal that the fracture angle and free surface depth significantly alter the crack propagation paths,whereas the influence of the fracture length is weaker.These parameters also affect the crack initiation time.The relative displacement evolution characteristics indicate that fracture angle,fracture length,and free surface depth affect the shape and size of the rotating block,the rotation center,and the rotation pivot point and degree,respectively.The grayscale characteristic evolution trends are similar for all examined overhanging rock specimens.The evolution of the grayscale indices based on DIC can be divided into high-frequency oscillation,smooth decline(or smooth downward concavity),and stable development stages.Furthermore,the multistage properties of the indices can be used to identify the fracture state of overhanging rocks,providing a theoretical basis for graded early warning of rockfall disasters.展开更多
基金financially supported by the National Natural Science Foundation of China under Grant Nos.52305467,52188102,U22A20196,and 52075201the Guangdong Basic and Applied Basic Research Foundation Nos.2023A1515010081 and 2022B1212020003the Fundamental Research Funds for the Central Universities under Grant No.YCJJ20230360.
文摘Solidification cracking(SC)of 2024 high-strength aluminium alloy during fusion welding or additive manufacturing has been a long-term issue.In this work,crack-free weld could be obtained using a Zr-core-Alshell wire(ZCASW filler material,a novel filler)coupled with an oscillating laser-arc hybrid welding process,and we investigated the solidification cracking susceptibility(SCS)and cracking behavior of AA2024 weld fabricated with different filler materials.The cracking inhibition mechanism of the weld fabricated with ZCASW filler material was elucidated by combined experiments and phase-field simulation.The results show that the effectiveness of filler materials in reducing the SC gradually improves in the order of ER2319 filler material<ER4043 filler material<ZCASW filler material.The main cracking(when using the ER2319 filler material)branches and the micro cracking branches interact with each other to produce cracking coalescence,which aggravates the cracking propagation.The formation of the Al_(3) Zr phase(when using the ZCASW filler material)promotes heterogeneous nucleation of α-Al,thereby resulting in finer and equiaxed non-dendrite structures,which shortens the liquid phase channels and decreases cracking susceptibility index|d T/d(f_(s))^(1/2)|(T is temperature and f_(s) is solidification fraction)at final solidification.A higher proportion(7.65%area fraction)of inter-dendrite phase with spherical distribution state,a shorter(8.6 mm liquid channel length)inter-dendrite phase coupled with round non-dendrite structure(6μm dendrite size)effectively inhibit the SC.The present study can be a useful database for welding and additive manufacturing of AA2024.
基金supported by the National Natural Science Foundation of China(Grant No.52278333)the China Scholarship Council(CSC)and the Science and Technology Department of Liaoning Province(Grant No.2024JH2/102500069).
文摘Peridynamics(PD)is an effective method for simulating the spontaneous initiation and propagation of tensile cracks in materials.However,it faces great challenges in simulating compression-shear cracking of geomaterials due to the lack of efficient contact-friction models.This paper introduces an original contact-friction model that leverages twin mesh and potential function principles within PD to model rock cracking under tensile and compressive stresses.The contact detection algorithm,based on space segmentation axis-aligned bounding box(AABB)tree data structure,is used to address the significant challenge of highly efficient contact detection in compression and shear problems.In this method,the twin mesh and potential function are utilized to quantify contact detection and contact degree,as well as friction behavior.This is in contrast to the distance and circular contact area model,which lacks physical significance in the classical PD method.As demonstrated by the tests on specimens containing cracks,the proposed model can capture 8 types of secondary fractures,reduce the contact detection error by about 29%e56%,and increase the contact retrieval efficiency by over 1600 times compared to the classic PD models.This significantly enhances the capability of PD to simulate the initiation,expansion,and coalescence of intricate compression-shear cracks.
基金supported by the State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering(Grant No.SKLGDUEK2206)National Natural Science Foundation of China(Grant No.11872340).
文摘Soil desiccation cracking is a common phenomenon on the earth surface.Numerical modeling is an effective approach to study the desiccation cracking mechanism of soil.This work develops a novel 3D moisture diffusion discrete model that is capable of dynamically assessing the effect of cracking on moisture diffusion and allowing moisture to be discontinuous on both sides of the cracks.Then,the parametric analysis of the moisture exchange coefficient in the 3D moisture diffusion discrete model is carried out for moisture diffusion in continuous media,and the selection criterion of the moisture exchange coefficient for the unbroken cohesive element is given.Subsequently,an example of moisture migration in a medium with one crack is provided to illustrate the crack hindering effect on moisture migration.Finally,combining the 3D moisture diffusion discrete model with the finite-discrete element method(FDEM),the moisture diffusion-fracture coupling model is built to study the desiccation cracking in a strip soil and the crack pattern of a rectangular soil.The evolution of crack area and volume with moisture content is quantitatively analyzed.The modeling number and average width of cracks in the strip soil show a good consistency with the experimental results,and the crack pattern of the rectangular soil matches well with the existing numerical results,validating the coupled moisture diffusion-fracture model.Additionally,the parametric study of soil desiccation cracking is performed.The developed model offers a powerful tool for exploring soil desiccation cracking.
基金supported by the National Key Research and Development Program of China(No.2021YFB3701000)the National Natural Science Foundation of China(Nos.51971130,52201129,U21A2047,51821001,U2037601)+2 种基金support by the China Postdoctoral Science Foun-dation(2023M742219)the Postdoctoral Fellowship Program of CPSF under Grant Number GZB20240419support by the Ministry of Education,Singapore,under its Academic Research Fund Tier 2(MOE-T2EP50221-0013).
文摘Additive manufacturing (AM) of high-strength metallic alloys frequently encounters detrimental distortion and cracking, attributed to the accumulation of thermal stresses. These issues significantly impede the practical application of as-printed components. This study examines the Mg-15Gd-1Zn-0.4Zr (GZ151K, wt.%) alloy, a prototypical high-strength casting Mg-RE alloy, fabricated through laser powder bed fusion (LPBF). Despite achieving ultra-high strength, the GZ151K alloy concurrently exhibits a pronounced cold-cracking susceptibility. The as-printed GZ151K alloy consists of almost fully fine equiaxed grains with an average grain size of merely 2.87 µm. Subsequent direct aging (T5) heat treatment induces the formation of dense prismatic β' precipitates. Consequently, the LPBF-T5 GZ151K alloy manifests an ultra-high yield strength of 405 MPa, surpassing all previously reported yield strengths for Mg alloys fabricated via LPBF and even exceeding that of its extrusion-T5 counterpart. Interestingly, as-printed GZ151K samples with a build height of 2 mm exhibit no cracking, whereas samples with build heights ranging from 4 to 18 mm demonstrate severe cold cracking. Thermal stress simulation also suggests that the cold cracking susceptibility increases significantly with increasing build height. The combination of high thermal stress and low ductility in the as-printed GZ151K alloy culminates in a high cold cracking susceptibility. This study offers novel insights into the intricate issue of cold cracking in the LPBF process of high-strength Mg alloys, highlighting the critical balance between achieving high strength and mitigating cold cracking susceptibility.
基金supported by the National Natural Science Foundation of China Projects under Grant(nos.52301112,52331004,U21A2049,and 51871211)Guangdong Basic and Applied Basic Research Foundation(Grant no.2024A1515030065)+4 种基金Basic and Applied Basic Research Project of Guangzhou(Grant no.2024A04J6299)LiaoNing Revitalization Talents Program(XLYC1907062,and XLYC2403026)Shenyang Young and Middle-aged Science and Technology Innovation Talent Support Program(RC231178)the Fundamental Research Funds for the Central Universities(N25GFY002)the Innovation Fund of Institute of Metal Research(IMR),Chinese Academy of Sciences(CAS).
文摘Mg-Li alloys hold significant potential for applications in aerospace,automotive manufacturing,military weaponry,and biomedical implants,due to their excellent recyclability,high specific strength,biocompatibility,and superior electromagnetic shielding properties.However,their poor corrosion resistance and high susceptibility to environmentally assisted cracking(EAC)significantly limit broader application.In recent years,growing attention has been directed toward understanding the corrosion and EAC behavior of Mg-Li alloys,as localized corrosion areas and hydrogen generated during the corrosion process can serve as crack initiation points and promote crack propagation.A comprehensive understanding of these mechanisms is essential for enhancing the reliability and performance of Mg-Li alloys in practical environments.This paper presents a detailed review of corrosion and EAC in Mg-Li alloys,focusing on corrosion behavior,crack initiation and propagation mechanisms,and the key factors influencing these processes.It summarizes recent advances in alloying,heat treatment,mechanical processing,microstructural control,environmental influences,mechanical loading,and surface treatments.In addition,the paper explores future research directions,highlights emerging trends,and proposes strategies to improve the durability and service performance of Mg-Li alloys.
文摘A comparative study of products of thermal and thermocatalytic cracking of polypropylene(PP) in the presence of potassium polytitanate(PPT) synthesized by treatment of TiO_(2)(rutile) powder with molten mixture of KOH and KNO_(3) taken in a weight ratio of 30∶30∶40 has been carried out.It was shown that the studied type of PPT powder exhibits catalytic properties in the reaction of thermal decomposition of PP,compared to the effect of commercial zeolite catalyst CBV-780 traditionally used for this purpose.Based on the analysis performed,the differences in the mechanism of catalytic action of PPT and the zeolite were considered.The reasons for the observed differences in the composition of PP cracking products and in the rate of coke formation on the surface of studied catalysts were analyzed.Considering the obtained results,it has been proposed that the CBV-780 catalyst promoted more intensive production of the gaseous hydrocarbons compared to PPT,due to higher specific surface area(internal surface) accessible for relatively light and small-sized hydrocarbon products of cracking.However,intensive coke formation on the outer surface of the microporous zeolite contributes to the blocking of transport channels and the rapid loss of catalytic action.At the same time,PPT,which initially has a smaller specific surface area,retains its catalytic activity significantly longer due to slit-shaped flat pores and higher transport accessibility of the inner surface.
基金The financial support provided by the Project of the National Natural Science Foundation of China (22308314,U22A20415)the Natural Science Foundation of Zhejiang Province (LQ24B060001)+1 种基金the "Pioneer" and "Leading Goose" Research & Development Program of Zhejiang (2022C01SA442617)the SINOPEC Technology Development Project (224244)
文摘This study leverages machine learning to perform high-throughput computational screening of n-hexane cracking initiators.Artificial neural networks are applied to predict the chemical performance of initiators,using simulated pyrolysis data as the training dataset.Various feature extraction methods are utilized,and five neural network architectures are developed to predict the co-cracking product distribution based on molecular structures.High-throughput screening of 12946 molecules outside the training dataset identifies the top 10 initiators for each target product—ethylene,propylene,and butadiene.The relative error between predicted and simulated values is less than 7%.Additionally,reaction pathway analysis elucidates the mechanisms by which initiators influence the distribution of cracking products.The proposed framework provides a practical and efficient approach for the rapid identification and evaluation of high-performance cracking initiators.
基金supported by Hunan Provincial Natural Science Foundation of China(Grant No.2022JJ40194)National Natural Science Foundation of China(Grant No.32102322)National Technology System for Grape Industry(Grant No.CARS-29-ZP-9)。
文摘Fruit cracking is a persistent challenge for table grape growing.To investigate the mechanism of this disorder,a comprehensive two-year investigation was conducted to assess the fruit cracking percentage of 15 table grape(Vitis vinifera L.)varieties.Based on the findings,the cracking-susceptible variety‘Xiangfei'and the cracking-resistant variety‘Zuijinxiang'were selected for further study.Fruit growth curves for‘Zuijinxiang'and‘Xiangfei'were plotted based on fruit diameter and total soluble solids content,revealing that both varieties exhibited typical double-sigmoidal patterns that were highly similar.The period between 48 and 53 days after full bloom(DAFB)was identified as the critical phase for fruit cracking incidence.Furthermore,during the fruit cracking period,‘Xiangfei'fruit exhibited significantly higher water content and mesocarp cell area compared with those of‘Zuijinxiang'.Applying aquaporin inhibitors(nano-silver)to‘Xiangfei'berries reduced fruit water uptake and cracking percentage,whereas applying aquaporin activators(forskolin)to‘Zuijinxiang'berries increased fruit water uptake and cracking percentage.Additionally,expression analysis of six genes associated with plasma membrane intrinsic proteins(PIPs)synthesis(VvPIP1;1,VvPIP1;2,VvPIP1;3,VvPIP2;1,VvPIP2;2,and VvPIP2;3)revealed that only the expression level of VvPIP1;1 was higher in‘Zuijinxiang'than in‘Xiangfei'during the fruit cracking period,whereas the expression levels of the other genes exhibited no significant difference between the two varieties.Transgenic overexpression of VvPIP1;1 in tomato resulted in increased fruit water content,enlarged mesocarp cell size,and enhanced fruit cracking percentage.These findings indicate that VvPIP1;1 plays a pivotal role in controlling grape berry cracking.
基金the financial support by the National Natural Science Foundation of China(Grant No.52108397)“Xiaohe”Science and Technology Talent Special Project(Grant No.2024 TJ-X06)Water Resources Science and Technology Project of Hunan Province(Grant No.XSKJ2023059-41).
文摘Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.
基金supported by the National Key Research and Development Program of China(Grant Nos.2023YFC3707900 and 2024YFC3012700)the National Natural Science Foundation of China(Grant No.42230710).
文摘Soil desiccation cracking is ubiquitous in nature and has significantpotential impacts on the engineering geological properties of soils.Previous studies have extensively examined various factors affecting soil cracking behavior through a numerous small-sample experiments.However,experimental studies alone cannot accurately describe soil cracking behavior.In this study,we firstly propose a modeling framework for predicting the surface crack ratio of soil desiccation cracking based on machine learning and interpretable analysis.The framework utilizes 1040 sets of soil cracking experimental data and employs random forest(RF),extreme gradient boosting(XGBoost),and artificialneural network(ANN)models to predict the surface crack ratio of soil desiccation cracking.To clarify the influenceof input features on soil cracking behavior,feature importance and Shapley additive explanations(SHAP)are applied for interpretability analysis.The results reveal that ensemble methods(RF and XGBoost)provide better predictive performance than the deep learning model(ANN).The feature importance analysis shows that soil desiccation cracking is primarily influencedby initial water content,plasticity index,finalwater content,liquid limit,sand content,clay content and thickness.Moreover,SHAP-based interpretability analysis further explores how soil cracking responds to various input variables.This study provides new insight into the evolution of soil cracking behavior,enhancing the understanding of its physical mechanisms and facilitating the assessment of potential regional development of soil desiccation cracking.
基金the National Natural Science Foundation of China(Nos.52471012,52471043).
文摘This study investigates the stress corrosion cracking(SCC)behavior of a Mg-8Gd-3Y-0.5Zr alloy in a 3.5 wt.%NaCl solution using slow strain rate tensile(SSRT)testing.The results reveal that SCC suscepti-bility increases as the strain rate decreases,with hydrogen embrittlement(HE)becoming more dominant at lower strain rates,leading to brittle fracture.Anodic dissolution(AD)plays a more significant role at higher strain rates,resulting in mixed fracture modes.Additionally,the mechanical properties and SCC resistance are strongly influenced by the sample orientation.TD-oriented samples show higher SCC susceptibility than RD-oriented ones due to the alignment of Gd-and Y-rich precipitates and grain boundaries,which act as initiation sites for SCC.These precipitates form micro-galvanic couples with the Mg matrix,accelerating localized corrosion and HE.The findings provide insights into the SCC mechanisms of VW83 alloy and highlight the importance of optimizing microstructure and processing conditions to improve its corrosion resistance.
基金supported by National Natural Science Foundation of China(Nos.52325406 and 52374330)Fundamental Research Funds for the Central Universities(No.N2225046).
文摘A mathematical model coupling flow,solidification,strain-stress,and interface failure was developed.Following identification of crack source type through thermal tensile experiment and validation by strain-stress comparison,the model was used to investigate slab cracking tendency near precipitated phases,considering various locations,sizes and shapes of them.The results show that the jet from submerged entry nozzle creates a“double roll”flow pattern during continuous casting,resulting in more uniform temperature distributions at slab corner and wide surface center compared with narrow surface center.Consequently,precipitated phases,particularly those located on the narrow surface,readily induce stress concentration and thus increase cracking tendency.A smaller precipitated phase size can reduce the stress concentration zone,while a more spherical shape can distribute surrounding stress along its surface and lower the internal stress within it,thereby decreasing the risk of slab cracking during continuous casting.The optimal precipitated phase exhibits a spherical or ellipsoidal shape with a major axis of less than 5µm,minimizing its potential to initiate cracks.
基金supported by the National Natural Science Foundation of China(Grant No.42277124)the National Key Research&Development Program of China(Grant No.2020YFC1808004)the Jiangsu Province 333 Talents Youth Talent Support Project.
文摘In subtropical regions,soil desiccation cracking often exerts a significant impact on the interactions between soil water and the atmosphere,making it a subject of great interest in the fields of geotechnical and geoenvironmental engineering.Despite the growing utilization of biochar as a sustainable soil amendment,there remains a lack of in-depth understanding of biocharewateresoil interactions,as well as its impact on soil desiccation cracking behavior.To address this gap,this study investigated the influence and mechanism of woody biochar dosages and particle sizes on the cracking behavior of three typical clayey soils in subtropical regions in China,namely Pukou expansive soil(PKE),Xiashu soil(XS),and Zhongshan lateritic soil(ZSL).The quantitative analysis of crack images revealed that the use of biochar was not consistently effective in preventing soil cracking.The application of biochar reduced the crack ratio in PKE and XS by up to 24.03%and 53.89%,respectively.In contrast,ZSL exhibited a 74.57%increase in crack ratio with the addition of 10%biochar.This influence can be further enhanced by increasing the dosage and reducing the particle size of biochar.The microstructural analysis demonstrated that biochar exerts an inhibitory effect on PKE and XS primarily through direct replacement,direct barrier,and indirect physical mechanisms.Moreover,an indirect chemical effect between biochar and clay particles was proposed to explain the exacerbated cracking observed in biochar-amended ZSL.To effectively utilize biochar for soil cracking mitigation in subtropical regions,it is essential to evaluate the initial mineral composition and cation type of the soil.
基金the financial support of the National Key Research and Development Program of China(2021YFE0112800)EU RISE project OPTIMAL(101007963).
文摘With growing concerns over environmental issues,ethylene manufacturing is shifting from a sole focus on economic benefits to an additional consideration of environmental impacts.The operation of the thermal cracking furnace in ethylene manufacturing determines not only the profitability of an ethylene plant but also the carbon emissions it releases.While multi-objective optimization of the thermal cracking furnace to balance profit with environmental impact is an effective solution to achieve green ethylene man-ufacturing,it carries a high computational demand due to the complex dynamic processes involved.In this work,artificial intelligence(AI)is applied to develop a novel hybrid model based on physically consistent machine learning(PCML).This hybrid model not only reduces the computational demand but also retains the interpretability and scalability of the model.With this hybrid model,the computational demand of the multi-objective dynamic optimization is reduced to 77 s.The optimization results show that dynamically adjusting the operating variables with coke formation can effectively improve profit and reduce CO_(2)emissions.In addition,the results from this study indicate that sacrificing 28.97%of the annual profit can significantly reduce the annual CO_(2)emissions by 42.89%.The key findings of this study highlight the great potential for green ethylene manufacturing based on AI through modeling and optimization approaches.This study will be important for industrial practitioners and policy-makers.
基金supported by the National Natural Science Foundation of China(52071175,52301304)the Natural Science Foundation of Jiangsu Province(BK20230704)+3 种基金the China Postdoctoral Science Foundation Funded Project(2023M731742)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province(23KJB430019)the Research Fund of Nanjing Institute of Technology(YKJ202402)the Open Research Fund of Jiangsu Key Laboratory for Light Metal Alloys(LMA202401).
文摘Implants are inevitably subjected to stress corrosion,bringing serious challenges to the controlled degradation of biomedical Mg alloys.It is worth studying the stress corrosion cracking(SCC)behavior of Mg alloy and exploring Mg alloy with good SCC resistance for wide biomedical applications.In this work,the as-cast and as-extruded Mg-3Gd-1Zn-0.4Zr(GZ31K)alloys with uniform corrosion were used to investigate SCC behavior.The as-extruded GZ31K alloy exhibited better corrosion resistance and mechanical properties than the as-cast one mainly owing to grain refinement and uniformly distributed fine precipitates,and possessed superior SCC resistance.To clarify the SCC mechanism,the slow strain rate tests were assisted with applied constant potentials via an electrochemical workstation.Accelerated anodic dissolution at anodic polarization deteriorated SCC resistance due to the initiation of corrosion pits and micro-cracks.However,cathodic polarization had no obvious effects on SCC resistance,along with both retarded corrosion and accelerated hydrogen evolution.Stacking faults in GZ31K alloy were hydrogen capture containers to reduce the effect of hydrogen on SCC resistance during cathodic polarization.These findings provide new insights into the evaluation of SCC mechanism,and offer more opportunities to explore Mg alloys with good SCC resistance by regulating anodic dissolution.
基金supports provided by the National Natural Science Foundation of China(No.52372330).
文摘The small punch test technique facilitates the convenient acquisition of the mechanical properties of in-service equipment materials and the assessment of their remaining service life through sampling.However,the weldability of components with thin walls after small punch sampling,such as ethylene cracking furnace tubes,requires further investigation.Therefore,the weldability of in-service ethylene cracking furnace tubes following small punch sampling was investigated through nondestructive testing,microstructural characterization,and mechanical testing.Additionally,the impact of small punch sampling size and residual stress on the creep performance of the specimens was studied using an improved ductility exhaustion model.The results indicate that both the surface and interior of the weld repair areas on new furnace tubes and service-exposed furnace tubes after small-punch sampling are defect-free,exhibiting good weld quality.The strength of the specimens after weld repair was higher than that before sampling,whereas toughness decreased.Weld repair following small punch sampling of furnace tubes is both feasible and necessary.Furthermore,a linear relationship was observed between specimen thickness,diameter,and creep fracture time.The residual stress of welding affects the creep performance of the specimen under different stresses.
基金supported by General Program of National Natural Science Foundation of China (22178385)。
文摘In this work,a new process for achieving the recovery of elemental sulfur by utilizing a fluidized catalytic cracking(FCC) riser reactor for SOxtreatment(FCC-DeSOx) is proposed.The process leverages the high temperatures and hydrocarbon concentrations in the FCC riser reactor to convert SOxinto H_(2)S.Subsequently,H_(2)S,along with the cracked gas,is processed downstream to produce sulfur.Thermodynamic analysis of the key reduction reactions in the FCC-DeSOxprocess revealed that complete conversion of SOxto H_(2)S is feasible in the dry gas(hydrogen-rich) prelift zone,as well as the upper and lower zones of the riser,upon achieving thermodynamic equilibrium.Experimental studies were conducted to replicate the conditions of these reaction zones using a low concentration of hydrogen gas as the reducing agent.Through process optimization,investigation of the minimum reaction time,and kinetic studies,the potential of this method for the complete reduction of SOxwas further confirmed.
基金support from the National Key Research and Development Program of China(No.2023YFB3710300)National Natural Science Foundation of China(Nos.12174296 and 52101088)+1 种基金Major Program(JD)of Hubei Province,China(No.2023BAA019-5)Numerical calculation is supported by the High-Performance Computing Center of Wuhan University of Science and Technology,China.
文摘The effect of aging precipitation on the stress corrosion cracking(SCC)mechanism of Ni(Fe,Al)-maraging steel was studied through the comparative characterization and analyses of the microstructures and fracture features of solid–solution and peak-aged steels.Aging precipitation exerts a chain of impacts on the deformative compatibility and electrochemical difference between the matrix and oth-er phases or interfaces.The strength of the martensite matrix is enhanced by abundant and evenly dispersed Ni(Fe,Al)precipitates,thereby reducing the possibility of splitting across martensite laths.Meanwhile,the Volta potential difference(VPD)between the matrix and primary NbC particles increases from 11.43 to 18.60 mV.Given that most of the primary NbC particles tend to be distributed along high-angle grain boundaries(HAGBs),anodic dissolution along HAGBs accelerates.Therefore,mechanical and electrochemical factors triggered by aging precipitation are involved in the variation in SCC behavior and mechanism.The SCC susceptibility of the steel in-creases along with the increasing tendency for intergranular cracking.
基金supported by the Innovative Research Group Project of the National Natural Science Foundation of China(22021004)Sinopec Major Science and Technology Projects(321123-1)。
文摘Coking at the fractionating tower bottom and the decant oil circulation system disrupts the heat balance,leading to unplanned shutdown and destroying the long period stable operation of the Fluid Catalytic Cracking Unit(FCCU).The FCCU operates through interconnected subsystems,generating high-dimensional,nonlinear,and non-stationary data characterized by spatiotemporally correlated.The decant oil solid content is the crucial indicator for monitoring catalyst loss from the reactor-regenerator system and coking risk tendency at the fractionating tower bottom that relies on sampling and laboratory testing,which is lagging responsiveness and labor-intensive.Developing the online decant oil solid content soft sensor using industrial data to support operators in conducting predictive maintenance is essential.Therefore,this paper proposes a hybrid deep learning framework for soft sensor development that combines spatiotemporal pattern extraction with interpretability,enabling accurate risk identification in dynamic operational conditions.This framework employs a Filter-Wrapper method for dimensionality reduction,followed by a 2D Convolutional Neural Network(2DCNN)for extracting spatial patterns,and a Bidirectional Gated Recurrent Unit(BiGRU)for capturing long-term temporal dependencies,with an Attention Mechanism(AM)to highlight critical features adaptively.The integration of SHapley Additive exPlanations(SHAP),Complementary Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN),2DCNN,and expert knowledge precisely quantifies feature contributions and decomposes signals,significantly enhancing the practicality of risk identification.Applied to a China refinery with processing capacity of 2.80×10^(6) t/a,the soft sensor achieved the R^(2) value of 0.93 and five-level risk identification accuracy of 96.42%.These results demonstrate the framework's accuracy,robustness,and suitability for complex industrial scenarios,advancing risk visualization and management.
基金supported by the China National Natural Science Foundation(Grant No.42362034)the Applied Basic Research Foundation of Yunnan Province,China(Grant No.202401AS070068).
文摘The destabilization of overhanging rock is a dangerous geological problem.In this study,a generalized model of typical overhanging cliffs from the Three Gorges Reservoir area in China with different fracture angles,fracture lengths,and free surface depths is constructed to investigate the cracking and deformation behavior of overhanging rocks.Laboratory tests and deformation field monitoring using the digital image correlation(DIC)method are performed on these specimens to reproduce the destabilization and failure process of overhanging rock under external loading.The influence of peak load is found to be the most sensitive to the fracture length,followed by the free surface depth,and to be the least sensitive to the fracture angle.The DIC-based strain fields reveal that the fracture angle and free surface depth significantly alter the crack propagation paths,whereas the influence of the fracture length is weaker.These parameters also affect the crack initiation time.The relative displacement evolution characteristics indicate that fracture angle,fracture length,and free surface depth affect the shape and size of the rotating block,the rotation center,and the rotation pivot point and degree,respectively.The grayscale characteristic evolution trends are similar for all examined overhanging rock specimens.The evolution of the grayscale indices based on DIC can be divided into high-frequency oscillation,smooth decline(or smooth downward concavity),and stable development stages.Furthermore,the multistage properties of the indices can be used to identify the fracture state of overhanging rocks,providing a theoretical basis for graded early warning of rockfall disasters.
