Behavior recognition of Hu sheep contributes to their intensive and intelligent farming.Due to the generally high density of Hu sheep farming,severe occlusion occurs among different behaviors and even among sheep perf...Behavior recognition of Hu sheep contributes to their intensive and intelligent farming.Due to the generally high density of Hu sheep farming,severe occlusion occurs among different behaviors and even among sheep performing the same behavior,leading to missing and false detection issues in existing behavior recognition methods.A high-low frequency aggregated attention and negative sample comprehensive score loss and comprehensive score soft non-maximum suppression-YOLO(HLNC-YOLO)was proposed for identifying the behavior of Hu sheep,addressing the issues of missed and erroneous detections caused by occlusion between Hu sheep in intensive farming.Firstly,images of four typical behaviors-standing,lying,eating,and drinking-were collected from the sheep farm to construct the Hu sheep behavior dataset(HSBD).Next,to solve the occlusion issues,during the training phase,the C2F-HLAtt module was integrated,which combined high-low frequency aggregation attention,into the YOLO v8 Backbone to perceive occluded objects and introduce an auxiliary reversible branch to retain more effective features.Using comprehensive score regression loss(CSLoss)to reduce the scores of suboptimal boxes and enhance the comprehensive scores of occluded object boxes.Finally,the soft comprehensive score non-maximal suppression(Soft-CS-NMS)algorithm filtered prediction boxes during the inferencing.Testing on the HSBD,HLNC-YOLO achieved a mean average precision(mAP@50)of 87.8%,with a memory footprint of 17.4 MB.This represented an improvement of 7.1,2.2,4.6,and 11 percentage points over YOLO v8,YOLO v9,YOLO v10,and Faster R-CNN,respectively.Research indicated that the HLNC-YOLO accurately identified the behavior of Hu sheep in intensive farming and possessed generalization capabilities,providing technical support for smart farming.展开更多
To investigate the influence of Al-Zn-Mg-Cu alloy with as-homogenized and as-rolled initial microstructures on the tensile flow behavior,isothermal tensile tests were conducted on a GLEEBLE-3500 isothermal simulator a...To investigate the influence of Al-Zn-Mg-Cu alloy with as-homogenized and as-rolled initial microstructures on the tensile flow behavior,isothermal tensile tests were conducted on a GLEEBLE-3500 isothermal simulator at temperatures of 380-440℃and strain rates of 0.05-1 s^(−1).The Johnson-Cook model,Hensel-Spittel model,strain-compensated Arrhenius model,and critical fracture strain model were established.Results show that through the evaluation of the models using the correlation coefficient(R)and the average absolute relative error,the strain-compensated Arrhenius model can represent the flow behavior of the alloy more accurately.Shear bands are more pronounced in the as-homogenized specimens,whereas dynamic recrystallization is predominantly observed in as-rolled specimens.Fracture morphology analysis reveals that a mixed fracture mechanism is prevalent in the as-homogenized specimen,whereas a ductile fracture mechanism is predominant in the as-rolled specimen.The processing maps indicate that the unstable region is reduced in the as-rolled specimens compared with that in the as-homogenized specimens.The optimal hot working windows for the as-homogenized and as-rolled specimens are determined as 410-440℃/0.14-1 s^(−1)and 380-400℃/0.05-0.29 s^(−1),respectively.展开更多
In this paper,we consider the fourth-order parabolic equation with p(x)Laplacian and variable exponent source ut+∆^(2)u−div(|■u|^(p(x)−2■u))=|u|^(q(x))−1u.By applying potential well method,we obtain global existence...In this paper,we consider the fourth-order parabolic equation with p(x)Laplacian and variable exponent source ut+∆^(2)u−div(|■u|^(p(x)−2■u))=|u|^(q(x))−1u.By applying potential well method,we obtain global existence,asymptotic behavior and blow-up of solutions with initial energy J(u_(0))≤d.Moreover,we estimate the upper bound of the blow-up time for J(u_(0))≤0.展开更多
Given the considerable global interest in the preparation of Ti and TiC,a novel reduction method for TiO_(2) in a CH_(4)-H_(2) atmosphere was proposed,and the reduction thermodynamic behavior,phase equilibrium,and ene...Given the considerable global interest in the preparation of Ti and TiC,a novel reduction method for TiO_(2) in a CH_(4)-H_(2) atmosphere was proposed,and the reduction thermodynamic behavior,phase equilibrium,and energy consumption of TiO_(2) during its reaction with a CH_(4)-H_(2) gas mixture were investigated.The results indicate that the reaction proceeds via a stepwise reduction pathway from TiO_(2) to Ti(C,O),with the Magnéli phase(TinO_(2n-1))and Ti_(3)O_(5) serving as intermediate phases.Notably,the reduction of TiO_(2) by H_(2) is more challenging than that by CH_(4),which may be attributed to the inhibitory effect of H_(2) on the surface carbon precipitation.For the complete carbonization of 1 mol TiO_(2),the total energy required at 1000,1100,and 1200℃is 1159,925,and 977 kJ/mol,respectively,which may be related to the shift of gas-phase equilibrium and the increase in side reactions at high temperatures.展开更多
Residential energy-use behavior and energy-saving awareness play a crucial role in sustainable urban energy planning and building energy efficiency,particularly under the pressures of climate change.However,existing s...Residential energy-use behavior and energy-saving awareness play a crucial role in sustainable urban energy planning and building energy efficiency,particularly under the pressures of climate change.However,existing studies often lack comparative analysis of urban-rural differences and tend to focus excessively on behavior patterns while neglecting the dimension of energysaving awareness.With China’s urbanization rate reaching 66.16%,understanding such regional disparities has become increasingly important.To address these research gaps,this study conducts a large-scale survey on space cooling behaviors among residents in Beijing,a representative Chinese megacity.It should be noted that living standards in such megacities are generally higher than the national average,which may shape distinctive energy-use profiles.Analyzing 1573valid samples(1064 urban/442 rural)in 2024,this study employed K-Prototypes and K-Modes clustering to identify typical cooling behavior and energy-saving awareness pattems,followed by Kendall/Chi-square correlation tests and XGBoost importance analysis to determine key influencing factors,with subsequent urban-rural comparative analysis.Results indicate that urban residents are primarily heat-sensitive or heat-tolerant,with a secondary patten of mid-low temperature preference,and generally exhibit long cooling durations;rural behavior is dominated by heat-tolerant type,followed by heat-sensitive,mid-low temperature preference,and never-on types as secondary patterns;both urban and rural areas exhibit energy-savingawareness characterized by low consumption-lowwillingness,though urban areas show marginally higher motivation;energy-saving awareness correlates with cooling behavior in rural areas,but this relationship weakens significantly in urban contexts.展开更多
Online examinations have become a dominant assessment mode,increasing concerns over academic integrity.To address the critical challenge of detecting cheating behaviours,this study proposes a hybrid deep learning appr...Online examinations have become a dominant assessment mode,increasing concerns over academic integrity.To address the critical challenge of detecting cheating behaviours,this study proposes a hybrid deep learning approach that combines visual detection and temporal behaviour classification.The methodology utilises object detection models—You Only Look Once(YOLOv12),Faster Region-based Convolutional Neural Network(RCNN),and Single Shot Detector(SSD)MobileNet—integrated with classification models such as Convolutional Neural Networks(CNN),Bidirectional Gated Recurrent Unit(Bi-GRU),and CNN-LSTM(Long Short-Term Memory).Two distinct datasets were used:the Online Exam Proctoring(EOP)dataset from Michigan State University and the School of Computer Science,Duy Tan Unievrsity(SCS-DTU)dataset collected in a controlled classroom setting.A diverse set of cheating behaviours,including book usage,unauthorised interaction,internet access,and mobile phone use,was categorised.Comprehensive experiments evaluated the models based on accuracy,precision,recall,training time,inference speed,and memory usage.We evaluate nine detector-classifier pairings under a unified budget and score them via a calibrated harmonic mean of detection and classification accuracies,enabling deployment-oriented selection under latency and memory constraints.Macro-Precision/Recall/F1 and Receiver Operating Characteristic-Area Under the Curve(ROC-AUC)are reported for the top configurations,revealing consistent advantages of object-centric pipelines for fine-grained cheating cues.The highest overall score is achieved by YOLOv12+CNN(97.15%accuracy),while SSD-MobileNet+CNN provides the best speed-efficiency trade-off for edge devices.This research provides valuable insights into selecting and deploying appropriate deep learning models for maintaining exam integrity under varying resource constraints.展开更多
Correction to:Nano-Micro Letters(2026)18:10.https://doi.org/10.1007/s40820-025-01852-8 Following publication of the original article[1],the authors reported that the last author’s name was inadvertently misspelled.Th...Correction to:Nano-Micro Letters(2026)18:10.https://doi.org/10.1007/s40820-025-01852-8 Following publication of the original article[1],the authors reported that the last author’s name was inadvertently misspelled.The published version showed“Hongzhen Chen”,whereas the correct spelling should be“Hongzheng Chen”.The correct author name has been provided in this Correction,and the original article[1]has been corrected.展开更多
With the rapid development of smart manufacturing,intelligent safety monitoring in industrial workshops has become increasingly important.To address the challenges of complex backgrounds,target scale variation,and exc...With the rapid development of smart manufacturing,intelligent safety monitoring in industrial workshops has become increasingly important.To address the challenges of complex backgrounds,target scale variation,and excessive model parameters in worker violation detection,this study proposes ADCP-YOLO,an enhanced lightweight model based on YOLOv8.Here,“ADCP”represents four key improvements:Alterable Kernel Convolution(AKConv),Dilated-Wise Residual(DWR)module,Channel Reconstruction Global Attention Mechanism(CRGAM),and Powerful-IoU loss.These components collaboratively enhance feature extraction,multi-scale perception,and localization accuracy while effectively reducing model complexity and computational cost.Experimental results show that ADCP-YOLO achieves a mAP of 90.6%,surpassing YOLOv8 by 3.0%with a 6.6%reduction in parameters.These findings demonstrate that ADCP-YOLO successfully balances accuracy and efficiency,offering a practical solution for intelligent safety monitoring in smart factory workshops.展开更多
Investigations into the long-term creep behavior of Beishan granite in uniaxial compression were conducted.Four levels of axial stress(60,70,87,and 95 MPa)were applied to rock specimens.Contrasting with earlier resear...Investigations into the long-term creep behavior of Beishan granite in uniaxial compression were conducted.Four levels of axial stress(60,70,87,and 95 MPa)were applied to rock specimens.Contrasting with earlier research,the long-term creep data in this work present a substantial advancement in the time dimension.Except for the sample subjected to 60 MPa axial loading,which did not fail after a loading duration of 1650 d,the specimens under the other three stresses all failed after sustained constant loading durations of 1204,1023,and 839 d,respectively.A lower envelope of driving stress-ratio for crystalline rocks was obtained,tending towards approximately 0.45 over an infinite time scale.According to the experimental results,as axial stress increases,both the axial strain accumulated in the transient creep process and the strain rate associated with steady-state creep deformation increase exponentially;however,the share of steady-state creep strain remains nearly constant at about82.53%.A novel damage-based creep model was put forward.It provides an enhanced depiction of the comprehensive creep process in rocks,notably improving the accuracy in forecasting the accelerated creep phase,which significantly impacts the long-term stability of engineering structures.展开更多
Drug products are specific goods with safety and effectiveness in medical health case.All of researchers(authors),reviewers,and editors must abide by medical ethical obligation,and also must deter to the ethical oblig...Drug products are specific goods with safety and effectiveness in medical health case.All of researchers(authors),reviewers,and editors must abide by medical ethical obligation,and also must deter to the ethical obligation for publication.These guidelines are offered as ethical behavior standards.We now present a set of ethical guidelines for persons engaged in the publication of drug research,specifically,for editors,authors,and reviewers.We believe that the guidelines offered are understood and subscribed to by the pharmaceutical research scientists.They may be helpful to those who are related to the editors,authors,and reviewers of journal publication.展开更多
BACKGROUND Despite societal guidelines recommending targeted screening for Barrett’s esophagus(BE)and esophageal adenocarcinoma(EAC)in individuals with gastroesophageal reflux symptoms(GERS),screening adherence is su...BACKGROUND Despite societal guidelines recommending targeted screening for Barrett’s esophagus(BE)and esophageal adenocarcinoma(EAC)in individuals with gastroesophageal reflux symptoms(GERS),screening adherence is suboptimal.Current screening approaches fail to identify individuals not seeking medical consultation for GERS or whose GERS are managed with‘over-the-counter’(OTC)acid suppressant therapies.AIM To assess patients’self-management and help-seeking behavior for GERS.METHODS This cross-sectional study collected data from the Dutch general population aged 18-75 years between January and April 2023 using a web-based survey.The survey included questions regarding self-management(e.g.,use of acid suppressant therapy with or without prescription)and help-seeking behavior(e.g.,consulting a primary care provider)for GERS.Simple random sampling was performed to select individuals within the target age group.In total,18156 randomly selected individuals were invited to participate.The study protocol was registered in ClinicalTrials.gov(identifier:NCT05689918).RESULTS Of the 18156 invited individuals,3214 participants(17.7%)completed the survey,of which 1572 participants(48.9%)reported GERS.Of these,904 participants(57.5%)had never consulted a primary care provider for these symptoms,of which 331 participants(36.6%)reported taking OTC acid suppressant therapy in the past six months and 100 participants(11.1%)fulfilled the screening criteria for BE and EAC according to the European Society of Gastrointestinal Endoscopy Guideline.CONCLUSION The population fulfilling the screening criteria for BE and EAC is incompletely identified,suggesting potential underutilization of medical consultation.Raising public awareness of GERS as a risk factor for EAC is needed.展开更多
Mesenchymal stem cell-derived extracellular vesicles have emerged as a promising form of regenerative and immunomodulatory therapy;indeed,micro(mi)RNAs contained within mesenchymal stem cell-derived extracellular vesi...Mesenchymal stem cell-derived extracellular vesicles have emerged as a promising form of regenerative and immunomodulatory therapy;indeed,micro(mi)RNAs contained within mesenchymal stem cell-derived extracellular vesicles modulate target gene expression and impact disease-associated pathways.Chronic alcohol consumption leads to neuroinflammation,brain damage,and impaired cognition.Evidence indicates that females are more vulnerable to alcohol-induced damage than males.While mesenchymal stem cell-derived extracellular vesicles have been studied in various neuroinflammatory conditions,their potential to counteract alcohol-induced brain damage remains unclear.In this study,we investigated whether repeated intravenous administration of mesenchymal stem cell-derived extracellular vesicles could ameliorate neuroinflammation and behavioral impairment induced by chronic alcohol consumption in female mice.Mesenchymal stem cell-derived extracellular vesicles diminished the increased binding of a micro-positron emission tomography tracer(^(18)F-FDG)when analyzing whole-brain 3D images and brain coronal sections of ethanol-treated mice.Mesenchymal stem cell-derived extracellular vesicle administration protected against ethanol-induced proinflammatory gene upregulation,cognitive dysfunction,and the conditioned rewarding effects of cocaine.MiRNA sequencing data from mesenchymal stem cell-derived extracellular vesicles revealed the elevated expression of extracellular vesicle-derived miR-483-5p and miR-140-3p in the brains of ethanol-treated female mice following mesenchymal stem cell-derived extracellular vesicle administration.In addition,mesenchymal stem cell-derived extracellular vesicles modulated the expression of pro-inflammatory-related miRNA target genes(e.g.,Socs3,Tnf,Mtor,and Atf6)in the brains of ethanol-treated female mice.These results suggest that mesenchymal stem cell-derived extracellular vesicles could function as a neuroprotective therapy to ameliorate the neuroinflammation,cognitive dysfunction,and conditioned rewarding effects of cocaine associated with chronic alcohol consumption.展开更多
This study utilizes wet/dry cyclic corrosion testing combined with corrosion big data technology to investigate the mechanism by which chloride ions(Cl^(-))influence the corrosion behavior of 650 MPa high-strength low...This study utilizes wet/dry cyclic corrosion testing combined with corrosion big data technology to investigate the mechanism by which chloride ions(Cl^(-))influence the corrosion behavior of 650 MPa high-strength low-alloy(HSLA)steel in industrially polluted environments.The corrosion process of 650 MPa HSLA steel occurred in two distinct stages:an initial corrosion stage and a stable corrosion stage.During the initial phase,the weight loss rate increased rapidly owing to the instability of the rust layer.Notably,this study demonstrated that 650 MPa HSLA steel exhibited superior corrosion resistance in Cl-containing environments.The formation of a corrosion-product film eventually reduced the weight-loss rate.However,the intrusion of Cl^(-)at increasing concentrations gradually destabilized theα/γ^(*)phases of the rust layer,leading to a looser structure and lower polarization resistance(R_(p)).The application of corrosion big data technology in this study facilitated the validation and analysis of the experimental results,offering new insights into the corrosion mechanisms of HSLA steel in chloride-rich environments.展开更多
Drilling and blasting tunneling is a cyclic process in which tunnel rock undergoes repeated blast loading,affecting its dynamic characteristics,energy evolution,and damage progression.To explore the dynamic mechanical...Drilling and blasting tunneling is a cyclic process in which tunnel rock undergoes repeated blast loading,affecting its dynamic characteristics,energy evolution,and damage progression.To explore the dynamic mechanical properties and damage mechanisms of carbonaceous slate under cyclic impact loads of varying intensities,cyclic dynamic tests are conducted using a triaxial split Hopkinson pressure bar.This study analyzes the stress-strain relationship,energy damage evolution,and macro-to-micro failure characteristics.The results show that peak stress and strain are significantly influenced by impact intensity and the number of impacts.The initial dynamic stress is positively correlated with the impact intensity,but with more impact,the dynamic stress decreases while the peak strain increases.Energy evolution follows a pattern of"slow growthfluctuating growthrapid growth,"with the crack initiation stress and its proportion decreasing.CT and SEM analyses reveal that as the impact intensity increases,failure becomes more chaotic,the fracture volume increases,and the fracture mode shifts from interlayer and intergranular to through-layer and trans-granular fractures.These findings provide an experimental basis for soft rock tunnel stability analysis.展开更多
Background:Amid the global rise in adolescent sedentary behavior and psychological distress,extant research has largely focused on variable-level associations,neglecting symptom-level interactions.This study applies n...Background:Amid the global rise in adolescent sedentary behavior and psychological distress,extant research has largely focused on variable-level associations,neglecting symptom-level interactions.This study applies network analysis,aims to delineate the interconnections among sedentary time,social support,social exclusion,and psychological distress in Chinese students,and to identify core and bridge symptoms to inform targeted interventions.Methods:This study employed a cross-sectional design to investigate the complex relationships among sedentary behavior,social support,social exclusion,and psychological distress among Chinese students.The research involved 459 high school and university students,using network analysis and mediation models to examine these relationships.Results:Network analysis revealed that the network had a density of 58.33%and an average edge weight of 0.11.In terms of centrality,stress had the highest expected influence(EI=1.135),acting as the core amplifier in the network.Sedentary behavior demonstrated the highest bridging expected influence,functioning as a critical bridge for cross-community transmission.Conversely,friend support showed the lowest bridging EI with a negative value,indicating its effectiveness in blocking cross-community diffusion and alleviating symptoms.Conclusion:With stress acting as the most influential“core engine”within the symptom network and sedentary behavior serving as the key“bridge”for cross-community transmission,interventions should first target stress to weaken the overall symptom cascade,followed by reducing sedentary behavior or enhancing friend support to disrupt cross-community pathways,thereby achieving a core-bridge dual blockade.展开更多
The volume change behavior of natural gas hydrate-bearing sediment is essential as it influences settlement,strength,and stiffness,which directly affect the stability of hydrate reservoirs during hydrate extraction or...The volume change behavior of natural gas hydrate-bearing sediment is essential as it influences settlement,strength,and stiffness,which directly affect the stability of hydrate reservoirs during hydrate extraction or in response to environmental changes.The volume change is influenced not only by stress but also by the formation and dissociation of hydrates.This study adopted a customized apparatus for one-dimensional compression tests,allowing independent control of gas pressure and effective stress.Tests were conducted on samples with different hydrate saturations along various temperature-gas pressure-effective stress paths,yielding some conclusions related to compressibility and creep.An unusual phenomenon was observed under low-stress conditions:hydrate formation led to shrinkage rather than expansion.Three potential mechanisms behind this occurrence were discussed.As hydrate saturation increases,the yield stress rises while the compression and swelling indexes remain minimally affected.After hydrate dissociation,the compression curve of hydrate-bearing sediment drops to that of hydrate-free sediment.Once hydrate is formed,the compression curve of hydrate-free sediment gradually approaches that of hydrate-bearing sediment during the subsequent loading.Under low-stress conditions,the creep of both hydrate-free and hydrate-bearing sediments is very weak.However,when stress increases,significantly beyond the yield stress,the creep of both sediments increases significantly,with hydrate-bearing sediment exhibiting much greater creep than hydrate-free sediment.展开更多
Objectives:24-h movement behaviors(24-HMB),encompassing physical activity,sedentary behavior,and sleep duration,are increasingly regarded as interrelated and important factors for mental health.However,evidence on the...Objectives:24-h movement behaviors(24-HMB),encompassing physical activity,sedentary behavior,and sleep duration,are increasingly regarded as interrelated and important factors for mental health.However,evidence on the comprehensive association of these behaviors with mental health in adults with diabetes in developing countries remains scarce.This study examined the association between 24-HMB guidelines and psychological health among adults with diabetes in developing countries.Methods:Data were retrieved from the World Health Organization’s study on Global Aging and Adult Health Survey dataset.Adults(N=1905)diagnosed with diabetes from five low-and middle-income countries were included.The exposure of interest was adherence to 24-HMB guidelines,depression,cognition,and quality of life(QoL).Multiple logistic and multiple linear regression analyses were used to examine the association between meeting 24-HMB guidelines and depression,cognition,and QoL,respectively.Results:This cross-sectional study revealed that 28.61%complied with all three 24-HMB guidelines.Diabetic patients who met more numbers of 24-HMB guidelines had lower depression risk(OR=0.74,95%CI:0.61 to 0.91,p=0.004),greater cognition(β=0.42,95%CI:0.25 to 0.60,p<0.001),and QoL(β=1.30,95%CI:1.04 to 1.55,p<0.001)with the non-compliant population.For specific combinations,meeting all three guidelines were significantly associated with lower odds of depression,improved cognitive function,and enhanced QoL(all p<0.001).Conclusion:These findings support that meeting 24-HMB guidelines in a single or combined movement behaviors was significantly related to reduced risk of depression,enhanced cognitive function,and improved QoL among individuals with diabetes.展开更多
Significant differences exist between deep and medium-shallow coalbed methane(CBM)reservoirs.The unclear understanding of flowback and production behavior severely constrains the development of deep CBM resources.To a...Significant differences exist between deep and medium-shallow coalbed methane(CBM)reservoirs.The unclear understanding of flowback and production behavior severely constrains the development of deep CBM resources.To address this challenge,guided by the gas-liquid two-phase flow theory in ultra-low permeability reservoirs,and integrating theoretical analysis,numerical simulation,and insights from production practices,this study classifies the flowback and production stages of deep CBM well considering the Daning-Jixian Block,Eastern Ordos Basin as a representative case.We summarize the flowback characteristics for each stage and establish a standard flowback production type curve,aiming to guide field operations.The results indicate that:(a)The production process of deep CBM horizontal wells can be divided into five distinct stages:initial single-phase water dewatering stage,initial gas appearance to peak water production stage,gas breakthrough to peak gas production stage,stable production and decline stage,and low-rate production stage.(b)Based on reservoir energy,two standard type curves for horizontal well flowback production are established:the‘Sufficient Reservoir Energy’type and the‘Insufficient Reservoir Energy’type.The former achieves a higher initial gas rate(up to 12×10^(4)m^(3)/d)but exhibits poorer stability,while the latter achieves a lower stable rate(up to 8×10^(4)m^(3)/d)but demonstrates stronger stability.Numerical simulation confirms these behavioral patterns and reveals the underlying mechanisms related to the effectively drained area where pressure is significantly depleted.The findings from this study have guided the flowback production operations in 53 deep CBM wells with positive results,demonstrating high potential for broad application.展开更多
Freeze-thaw(F-T)cycle is receiving increasing attention as a primary threat to the long-term stability of rock engineering in high-elevation regions.In this study,artificial F-T cycle tests are first conducted on pre-...Freeze-thaw(F-T)cycle is receiving increasing attention as a primary threat to the long-term stability of rock engineering in high-elevation regions.In this study,artificial F-T cycle tests are first conducted on pre-flawed sandstone specimens with real-time frost heave pressure(FHP)monitoring,followed by subsequent cyclic loading tests with different maximum stresses.Given the water-ice-sandstone interaction,the evolution process of FHP in flaws can be divided into six phases,i.e.initial,silence,eruption,reduction,second-arising,and dissipation phases.Its magnitude exhibits an exponential decrease with increasing F-T cycle number.The influences of F-T cycles and the maximum stress on the fatigue mechanical characteristics of flawed sandstone are revealed.Subjected to higher F-T cycles and maximum stress,larger irreversible strain and less dissipated energy are accumulated inside flawed sandstone specimens,leading to faster damage and lower fatigue life.The three-stage evolution characters of irreversible strain and dissipated energy are both weakened by repeated F-T treatment,i.e.the prolonged initial and accelerated stages and shortened stable stage.In addition,the repeated F-T cycles diminish the impact of prefabricated flaws on cracking behavior of flawed sandstone specimens,and the fatigue failure pattern changes from shear-dominated failure with a transfixion shear band to tensile-dominated failure with massive tensile cracks as the F-T cycle number increases.Employing the scanning electron microscopy(SEM),the underlying damage mechanisms of flawed rocks under the coupling effect of F-T treatment and cyclic loading are discussed.Finally,an F-T-fatigue damage model is proposed based on FHP evolution and irreversible strain,which possesses distinct physical significance and reasonably quantifies the F-T deterioration and fatigue damage accumulation of flawed rocks.展开更多
Zn-Mn alloys are regarded as promising biodegradable metals for orthopedic applications owing to their moderate degradation rates and favorable osteogenic properties.However,the presence of a substantial number of sec...Zn-Mn alloys are regarded as promising biodegradable metals for orthopedic applications owing to their moderate degradation rates and favorable osteogenic properties.However,the presence of a substantial number of second-phase particles in Zn-based alloys might induce severe localized degradation via micro-coupling corrosion,thereby compromising the mechanical integrity of the alloy during in vivo tissue regeneration.In this study,high pressure solid solution(HPSS)treatment was conducted at 5 GPa and 380℃ for 1 h to fabricate Zn-0.5 Mn alloys.Microstructural characterization revealed that the HPSS treatment facilitated the formation of a supersaturated solid solution by completely dissolving theζ-MnZn_(13) phase into theα-Zn matrix.The resultant strengthening mechanisms,including supersaturated solid solution strengthening,grain-size strengthening,and dislocation strengthening,collectively enhanced the compressive yield strength(σ_(cys))of the Zn-0.5 Mn alloy to about 183.7 MPa,approximately three times that of the as-cast(AC)Zn-0.5 Mn alloy.Moreover,compared with the AC alloy,the HPSS Zn-0.5 Mn alloy exhibited uniform degradation behavior with a markedly reduced degradation rate.展开更多
文摘Behavior recognition of Hu sheep contributes to their intensive and intelligent farming.Due to the generally high density of Hu sheep farming,severe occlusion occurs among different behaviors and even among sheep performing the same behavior,leading to missing and false detection issues in existing behavior recognition methods.A high-low frequency aggregated attention and negative sample comprehensive score loss and comprehensive score soft non-maximum suppression-YOLO(HLNC-YOLO)was proposed for identifying the behavior of Hu sheep,addressing the issues of missed and erroneous detections caused by occlusion between Hu sheep in intensive farming.Firstly,images of four typical behaviors-standing,lying,eating,and drinking-were collected from the sheep farm to construct the Hu sheep behavior dataset(HSBD).Next,to solve the occlusion issues,during the training phase,the C2F-HLAtt module was integrated,which combined high-low frequency aggregation attention,into the YOLO v8 Backbone to perceive occluded objects and introduce an auxiliary reversible branch to retain more effective features.Using comprehensive score regression loss(CSLoss)to reduce the scores of suboptimal boxes and enhance the comprehensive scores of occluded object boxes.Finally,the soft comprehensive score non-maximal suppression(Soft-CS-NMS)algorithm filtered prediction boxes during the inferencing.Testing on the HSBD,HLNC-YOLO achieved a mean average precision(mAP@50)of 87.8%,with a memory footprint of 17.4 MB.This represented an improvement of 7.1,2.2,4.6,and 11 percentage points over YOLO v8,YOLO v9,YOLO v10,and Faster R-CNN,respectively.Research indicated that the HLNC-YOLO accurately identified the behavior of Hu sheep in intensive farming and possessed generalization capabilities,providing technical support for smart farming.
文摘To investigate the influence of Al-Zn-Mg-Cu alloy with as-homogenized and as-rolled initial microstructures on the tensile flow behavior,isothermal tensile tests were conducted on a GLEEBLE-3500 isothermal simulator at temperatures of 380-440℃and strain rates of 0.05-1 s^(−1).The Johnson-Cook model,Hensel-Spittel model,strain-compensated Arrhenius model,and critical fracture strain model were established.Results show that through the evaluation of the models using the correlation coefficient(R)and the average absolute relative error,the strain-compensated Arrhenius model can represent the flow behavior of the alloy more accurately.Shear bands are more pronounced in the as-homogenized specimens,whereas dynamic recrystallization is predominantly observed in as-rolled specimens.Fracture morphology analysis reveals that a mixed fracture mechanism is prevalent in the as-homogenized specimen,whereas a ductile fracture mechanism is predominant in the as-rolled specimen.The processing maps indicate that the unstable region is reduced in the as-rolled specimens compared with that in the as-homogenized specimens.The optimal hot working windows for the as-homogenized and as-rolled specimens are determined as 410-440℃/0.14-1 s^(−1)and 380-400℃/0.05-0.29 s^(−1),respectively.
基金Supported by NSFC(No.12101482)the Natural Science Foundation of Shaanxi Province,China(No.2018JQ1052)。
文摘In this paper,we consider the fourth-order parabolic equation with p(x)Laplacian and variable exponent source ut+∆^(2)u−div(|■u|^(p(x)−2■u))=|u|^(q(x))−1u.By applying potential well method,we obtain global existence,asymptotic behavior and blow-up of solutions with initial energy J(u_(0))≤d.Moreover,we estimate the upper bound of the blow-up time for J(u_(0))≤0.
文摘Given the considerable global interest in the preparation of Ti and TiC,a novel reduction method for TiO_(2) in a CH_(4)-H_(2) atmosphere was proposed,and the reduction thermodynamic behavior,phase equilibrium,and energy consumption of TiO_(2) during its reaction with a CH_(4)-H_(2) gas mixture were investigated.The results indicate that the reaction proceeds via a stepwise reduction pathway from TiO_(2) to Ti(C,O),with the Magnéli phase(TinO_(2n-1))and Ti_(3)O_(5) serving as intermediate phases.Notably,the reduction of TiO_(2) by H_(2) is more challenging than that by CH_(4),which may be attributed to the inhibitory effect of H_(2) on the surface carbon precipitation.For the complete carbonization of 1 mol TiO_(2),the total energy required at 1000,1100,and 1200℃is 1159,925,and 977 kJ/mol,respectively,which may be related to the shift of gas-phase equilibrium and the increase in side reactions at high temperatures.
文摘Residential energy-use behavior and energy-saving awareness play a crucial role in sustainable urban energy planning and building energy efficiency,particularly under the pressures of climate change.However,existing studies often lack comparative analysis of urban-rural differences and tend to focus excessively on behavior patterns while neglecting the dimension of energysaving awareness.With China’s urbanization rate reaching 66.16%,understanding such regional disparities has become increasingly important.To address these research gaps,this study conducts a large-scale survey on space cooling behaviors among residents in Beijing,a representative Chinese megacity.It should be noted that living standards in such megacities are generally higher than the national average,which may shape distinctive energy-use profiles.Analyzing 1573valid samples(1064 urban/442 rural)in 2024,this study employed K-Prototypes and K-Modes clustering to identify typical cooling behavior and energy-saving awareness pattems,followed by Kendall/Chi-square correlation tests and XGBoost importance analysis to determine key influencing factors,with subsequent urban-rural comparative analysis.Results indicate that urban residents are primarily heat-sensitive or heat-tolerant,with a secondary patten of mid-low temperature preference,and generally exhibit long cooling durations;rural behavior is dominated by heat-tolerant type,followed by heat-sensitive,mid-low temperature preference,and never-on types as secondary patterns;both urban and rural areas exhibit energy-savingawareness characterized by low consumption-lowwillingness,though urban areas show marginally higher motivation;energy-saving awareness correlates with cooling behavior in rural areas,but this relationship weakens significantly in urban contexts.
文摘Online examinations have become a dominant assessment mode,increasing concerns over academic integrity.To address the critical challenge of detecting cheating behaviours,this study proposes a hybrid deep learning approach that combines visual detection and temporal behaviour classification.The methodology utilises object detection models—You Only Look Once(YOLOv12),Faster Region-based Convolutional Neural Network(RCNN),and Single Shot Detector(SSD)MobileNet—integrated with classification models such as Convolutional Neural Networks(CNN),Bidirectional Gated Recurrent Unit(Bi-GRU),and CNN-LSTM(Long Short-Term Memory).Two distinct datasets were used:the Online Exam Proctoring(EOP)dataset from Michigan State University and the School of Computer Science,Duy Tan Unievrsity(SCS-DTU)dataset collected in a controlled classroom setting.A diverse set of cheating behaviours,including book usage,unauthorised interaction,internet access,and mobile phone use,was categorised.Comprehensive experiments evaluated the models based on accuracy,precision,recall,training time,inference speed,and memory usage.We evaluate nine detector-classifier pairings under a unified budget and score them via a calibrated harmonic mean of detection and classification accuracies,enabling deployment-oriented selection under latency and memory constraints.Macro-Precision/Recall/F1 and Receiver Operating Characteristic-Area Under the Curve(ROC-AUC)are reported for the top configurations,revealing consistent advantages of object-centric pipelines for fine-grained cheating cues.The highest overall score is achieved by YOLOv12+CNN(97.15%accuracy),while SSD-MobileNet+CNN provides the best speed-efficiency trade-off for edge devices.This research provides valuable insights into selecting and deploying appropriate deep learning models for maintaining exam integrity under varying resource constraints.
文摘Correction to:Nano-Micro Letters(2026)18:10.https://doi.org/10.1007/s40820-025-01852-8 Following publication of the original article[1],the authors reported that the last author’s name was inadvertently misspelled.The published version showed“Hongzhen Chen”,whereas the correct spelling should be“Hongzheng Chen”.The correct author name has been provided in this Correction,and the original article[1]has been corrected.
基金TheNationalNatural Science Foundation ofChina(Nos.62272418,62102058)Zhejiang Provincial Natural Science Foundation Major Project(No.LD24F020004)the Major Open Project of Key Laboratory for Advanced Design and Intelligent Computing of the Ministry of Education(No.ADIC2023ZD001).
文摘With the rapid development of smart manufacturing,intelligent safety monitoring in industrial workshops has become increasingly important.To address the challenges of complex backgrounds,target scale variation,and excessive model parameters in worker violation detection,this study proposes ADCP-YOLO,an enhanced lightweight model based on YOLOv8.Here,“ADCP”represents four key improvements:Alterable Kernel Convolution(AKConv),Dilated-Wise Residual(DWR)module,Channel Reconstruction Global Attention Mechanism(CRGAM),and Powerful-IoU loss.These components collaboratively enhance feature extraction,multi-scale perception,and localization accuracy while effectively reducing model complexity and computational cost.Experimental results show that ADCP-YOLO achieves a mAP of 90.6%,surpassing YOLOv8 by 3.0%with a 6.6%reduction in parameters.These findings demonstrate that ADCP-YOLO successfully balances accuracy and efficiency,offering a practical solution for intelligent safety monitoring in smart factory workshops.
基金financially supported by the China Atomic Energy Authority(CAEA)through the Geological Disposal Programthe National Natural Science Foundation of China(No.42307258)the China National Nuclear Corporation Fundamental Research Project(No.CNNC-JCYJ-202307)。
文摘Investigations into the long-term creep behavior of Beishan granite in uniaxial compression were conducted.Four levels of axial stress(60,70,87,and 95 MPa)were applied to rock specimens.Contrasting with earlier research,the long-term creep data in this work present a substantial advancement in the time dimension.Except for the sample subjected to 60 MPa axial loading,which did not fail after a loading duration of 1650 d,the specimens under the other three stresses all failed after sustained constant loading durations of 1204,1023,and 839 d,respectively.A lower envelope of driving stress-ratio for crystalline rocks was obtained,tending towards approximately 0.45 over an infinite time scale.According to the experimental results,as axial stress increases,both the axial strain accumulated in the transient creep process and the strain rate associated with steady-state creep deformation increase exponentially;however,the share of steady-state creep strain remains nearly constant at about82.53%.A novel damage-based creep model was put forward.It provides an enhanced depiction of the comprehensive creep process in rocks,notably improving the accuracy in forecasting the accelerated creep phase,which significantly impacts the long-term stability of engineering structures.
文摘Drug products are specific goods with safety and effectiveness in medical health case.All of researchers(authors),reviewers,and editors must abide by medical ethical obligation,and also must deter to the ethical obligation for publication.These guidelines are offered as ethical behavior standards.We now present a set of ethical guidelines for persons engaged in the publication of drug research,specifically,for editors,authors,and reviewers.We believe that the guidelines offered are understood and subscribed to by the pharmaceutical research scientists.They may be helpful to those who are related to the editors,authors,and reviewers of journal publication.
文摘BACKGROUND Despite societal guidelines recommending targeted screening for Barrett’s esophagus(BE)and esophageal adenocarcinoma(EAC)in individuals with gastroesophageal reflux symptoms(GERS),screening adherence is suboptimal.Current screening approaches fail to identify individuals not seeking medical consultation for GERS or whose GERS are managed with‘over-the-counter’(OTC)acid suppressant therapies.AIM To assess patients’self-management and help-seeking behavior for GERS.METHODS This cross-sectional study collected data from the Dutch general population aged 18-75 years between January and April 2023 using a web-based survey.The survey included questions regarding self-management(e.g.,use of acid suppressant therapy with or without prescription)and help-seeking behavior(e.g.,consulting a primary care provider)for GERS.Simple random sampling was performed to select individuals within the target age group.In total,18156 randomly selected individuals were invited to participate.The study protocol was registered in ClinicalTrials.gov(identifier:NCT05689918).RESULTS Of the 18156 invited individuals,3214 participants(17.7%)completed the survey,of which 1572 participants(48.9%)reported GERS.Of these,904 participants(57.5%)had never consulted a primary care provider for these symptoms,of which 331 participants(36.6%)reported taking OTC acid suppressant therapy in the past six months and 100 participants(11.1%)fulfilled the screening criteria for BE and EAC according to the European Society of Gastrointestinal Endoscopy Guideline.CONCLUSION The population fulfilling the screening criteria for BE and EAC is incompletely identified,suggesting potential underutilization of medical consultation.Raising public awareness of GERS as a risk factor for EAC is needed.
基金supported by the Spanish Ministry of Health‐Plan Nacional sobre Drogas(2023‐I024)the the Ministry of Science,Innovation and Universities/State ResearchAgency/10.13039/501100011033(PID2023-146865OB-I00)+2 种基金Generalitat Valenciana(CIAICO/2021/203)the Primary Addiction Care Research Network(RD21/0009/0005)FEDER Funds,GVA.
文摘Mesenchymal stem cell-derived extracellular vesicles have emerged as a promising form of regenerative and immunomodulatory therapy;indeed,micro(mi)RNAs contained within mesenchymal stem cell-derived extracellular vesicles modulate target gene expression and impact disease-associated pathways.Chronic alcohol consumption leads to neuroinflammation,brain damage,and impaired cognition.Evidence indicates that females are more vulnerable to alcohol-induced damage than males.While mesenchymal stem cell-derived extracellular vesicles have been studied in various neuroinflammatory conditions,their potential to counteract alcohol-induced brain damage remains unclear.In this study,we investigated whether repeated intravenous administration of mesenchymal stem cell-derived extracellular vesicles could ameliorate neuroinflammation and behavioral impairment induced by chronic alcohol consumption in female mice.Mesenchymal stem cell-derived extracellular vesicles diminished the increased binding of a micro-positron emission tomography tracer(^(18)F-FDG)when analyzing whole-brain 3D images and brain coronal sections of ethanol-treated mice.Mesenchymal stem cell-derived extracellular vesicle administration protected against ethanol-induced proinflammatory gene upregulation,cognitive dysfunction,and the conditioned rewarding effects of cocaine.MiRNA sequencing data from mesenchymal stem cell-derived extracellular vesicles revealed the elevated expression of extracellular vesicle-derived miR-483-5p and miR-140-3p in the brains of ethanol-treated female mice following mesenchymal stem cell-derived extracellular vesicle administration.In addition,mesenchymal stem cell-derived extracellular vesicles modulated the expression of pro-inflammatory-related miRNA target genes(e.g.,Socs3,Tnf,Mtor,and Atf6)in the brains of ethanol-treated female mice.These results suggest that mesenchymal stem cell-derived extracellular vesicles could function as a neuroprotective therapy to ameliorate the neuroinflammation,cognitive dysfunction,and conditioned rewarding effects of cocaine associated with chronic alcohol consumption.
基金financially supported by the National Natural Science Foundation of China(Nos.52104319 and 52374323)。
文摘This study utilizes wet/dry cyclic corrosion testing combined with corrosion big data technology to investigate the mechanism by which chloride ions(Cl^(-))influence the corrosion behavior of 650 MPa high-strength low-alloy(HSLA)steel in industrially polluted environments.The corrosion process of 650 MPa HSLA steel occurred in two distinct stages:an initial corrosion stage and a stable corrosion stage.During the initial phase,the weight loss rate increased rapidly owing to the instability of the rust layer.Notably,this study demonstrated that 650 MPa HSLA steel exhibited superior corrosion resistance in Cl-containing environments.The formation of a corrosion-product film eventually reduced the weight-loss rate.However,the intrusion of Cl^(-)at increasing concentrations gradually destabilized theα/γ^(*)phases of the rust layer,leading to a looser structure and lower polarization resistance(R_(p)).The application of corrosion big data technology in this study facilitated the validation and analysis of the experimental results,offering new insights into the corrosion mechanisms of HSLA steel in chloride-rich environments.
基金support from the Joint Funds of the National Natural Science Foundation of China(Grant No.U23A2060)the National Natural Science Foundation of China(Grant Nos.42177143 and 52474150).
文摘Drilling and blasting tunneling is a cyclic process in which tunnel rock undergoes repeated blast loading,affecting its dynamic characteristics,energy evolution,and damage progression.To explore the dynamic mechanical properties and damage mechanisms of carbonaceous slate under cyclic impact loads of varying intensities,cyclic dynamic tests are conducted using a triaxial split Hopkinson pressure bar.This study analyzes the stress-strain relationship,energy damage evolution,and macro-to-micro failure characteristics.The results show that peak stress and strain are significantly influenced by impact intensity and the number of impacts.The initial dynamic stress is positively correlated with the impact intensity,but with more impact,the dynamic stress decreases while the peak strain increases.Energy evolution follows a pattern of"slow growthfluctuating growthrapid growth,"with the crack initiation stress and its proportion decreasing.CT and SEM analyses reveal that as the impact intensity increases,failure becomes more chaotic,the fracture volume increases,and the fracture mode shifts from interlayer and intergranular to through-layer and trans-granular fractures.These findings provide an experimental basis for soft rock tunnel stability analysis.
文摘Background:Amid the global rise in adolescent sedentary behavior and psychological distress,extant research has largely focused on variable-level associations,neglecting symptom-level interactions.This study applies network analysis,aims to delineate the interconnections among sedentary time,social support,social exclusion,and psychological distress in Chinese students,and to identify core and bridge symptoms to inform targeted interventions.Methods:This study employed a cross-sectional design to investigate the complex relationships among sedentary behavior,social support,social exclusion,and psychological distress among Chinese students.The research involved 459 high school and university students,using network analysis and mediation models to examine these relationships.Results:Network analysis revealed that the network had a density of 58.33%and an average edge weight of 0.11.In terms of centrality,stress had the highest expected influence(EI=1.135),acting as the core amplifier in the network.Sedentary behavior demonstrated the highest bridging expected influence,functioning as a critical bridge for cross-community transmission.Conversely,friend support showed the lowest bridging EI with a negative value,indicating its effectiveness in blocking cross-community diffusion and alleviating symptoms.Conclusion:With stress acting as the most influential“core engine”within the symptom network and sedentary behavior serving as the key“bridge”for cross-community transmission,interventions should first target stress to weaken the overall symptom cascade,followed by reducing sedentary behavior or enhancing friend support to disrupt cross-community pathways,thereby achieving a core-bridge dual blockade.
基金supported by the National Natural Science Foundation of China(Grant No.42171135)the Science and Technology Program of CNOOC Research Institute(Grant No.2023OTKK03)the“CUG Scholar”Scientific Research Funds at China University of Geosciences(Project No.2022098).
文摘The volume change behavior of natural gas hydrate-bearing sediment is essential as it influences settlement,strength,and stiffness,which directly affect the stability of hydrate reservoirs during hydrate extraction or in response to environmental changes.The volume change is influenced not only by stress but also by the formation and dissociation of hydrates.This study adopted a customized apparatus for one-dimensional compression tests,allowing independent control of gas pressure and effective stress.Tests were conducted on samples with different hydrate saturations along various temperature-gas pressure-effective stress paths,yielding some conclusions related to compressibility and creep.An unusual phenomenon was observed under low-stress conditions:hydrate formation led to shrinkage rather than expansion.Three potential mechanisms behind this occurrence were discussed.As hydrate saturation increases,the yield stress rises while the compression and swelling indexes remain minimally affected.After hydrate dissociation,the compression curve of hydrate-bearing sediment drops to that of hydrate-free sediment.Once hydrate is formed,the compression curve of hydrate-free sediment gradually approaches that of hydrate-bearing sediment during the subsequent loading.Under low-stress conditions,the creep of both hydrate-free and hydrate-bearing sediments is very weak.However,when stress increases,significantly beyond the yield stress,the creep of both sediments increases significantly,with hydrate-bearing sediment exhibiting much greater creep than hydrate-free sediment.
文摘Objectives:24-h movement behaviors(24-HMB),encompassing physical activity,sedentary behavior,and sleep duration,are increasingly regarded as interrelated and important factors for mental health.However,evidence on the comprehensive association of these behaviors with mental health in adults with diabetes in developing countries remains scarce.This study examined the association between 24-HMB guidelines and psychological health among adults with diabetes in developing countries.Methods:Data were retrieved from the World Health Organization’s study on Global Aging and Adult Health Survey dataset.Adults(N=1905)diagnosed with diabetes from five low-and middle-income countries were included.The exposure of interest was adherence to 24-HMB guidelines,depression,cognition,and quality of life(QoL).Multiple logistic and multiple linear regression analyses were used to examine the association between meeting 24-HMB guidelines and depression,cognition,and QoL,respectively.Results:This cross-sectional study revealed that 28.61%complied with all three 24-HMB guidelines.Diabetic patients who met more numbers of 24-HMB guidelines had lower depression risk(OR=0.74,95%CI:0.61 to 0.91,p=0.004),greater cognition(β=0.42,95%CI:0.25 to 0.60,p<0.001),and QoL(β=1.30,95%CI:1.04 to 1.55,p<0.001)with the non-compliant population.For specific combinations,meeting all three guidelines were significantly associated with lower odds of depression,improved cognitive function,and enhanced QoL(all p<0.001).Conclusion:These findings support that meeting 24-HMB guidelines in a single or combined movement behaviors was significantly related to reduced risk of depression,enhanced cognitive function,and improved QoL among individuals with diabetes.
基金supported by the National Science and Technology Major Project of China(No.2025ZD1405702)the Scientific Research and Technology Development Project of PetroChina Coalbed Methane Co.,Ltd.(Project No.25MQCTSG010)Applied Science and Technology Project of PetroChina Company Limited(2023ZZ18YJ04).
文摘Significant differences exist between deep and medium-shallow coalbed methane(CBM)reservoirs.The unclear understanding of flowback and production behavior severely constrains the development of deep CBM resources.To address this challenge,guided by the gas-liquid two-phase flow theory in ultra-low permeability reservoirs,and integrating theoretical analysis,numerical simulation,and insights from production practices,this study classifies the flowback and production stages of deep CBM well considering the Daning-Jixian Block,Eastern Ordos Basin as a representative case.We summarize the flowback characteristics for each stage and establish a standard flowback production type curve,aiming to guide field operations.The results indicate that:(a)The production process of deep CBM horizontal wells can be divided into five distinct stages:initial single-phase water dewatering stage,initial gas appearance to peak water production stage,gas breakthrough to peak gas production stage,stable production and decline stage,and low-rate production stage.(b)Based on reservoir energy,two standard type curves for horizontal well flowback production are established:the‘Sufficient Reservoir Energy’type and the‘Insufficient Reservoir Energy’type.The former achieves a higher initial gas rate(up to 12×10^(4)m^(3)/d)but exhibits poorer stability,while the latter achieves a lower stable rate(up to 8×10^(4)m^(3)/d)but demonstrates stronger stability.Numerical simulation confirms these behavioral patterns and reveals the underlying mechanisms related to the effectively drained area where pressure is significantly depleted.The findings from this study have guided the flowback production operations in 53 deep CBM wells with positive results,demonstrating high potential for broad application.
基金support from the National Natural Science Foundation of China(Grant Nos.42377144,52225904 and 52039007)supported by the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘Freeze-thaw(F-T)cycle is receiving increasing attention as a primary threat to the long-term stability of rock engineering in high-elevation regions.In this study,artificial F-T cycle tests are first conducted on pre-flawed sandstone specimens with real-time frost heave pressure(FHP)monitoring,followed by subsequent cyclic loading tests with different maximum stresses.Given the water-ice-sandstone interaction,the evolution process of FHP in flaws can be divided into six phases,i.e.initial,silence,eruption,reduction,second-arising,and dissipation phases.Its magnitude exhibits an exponential decrease with increasing F-T cycle number.The influences of F-T cycles and the maximum stress on the fatigue mechanical characteristics of flawed sandstone are revealed.Subjected to higher F-T cycles and maximum stress,larger irreversible strain and less dissipated energy are accumulated inside flawed sandstone specimens,leading to faster damage and lower fatigue life.The three-stage evolution characters of irreversible strain and dissipated energy are both weakened by repeated F-T treatment,i.e.the prolonged initial and accelerated stages and shortened stable stage.In addition,the repeated F-T cycles diminish the impact of prefabricated flaws on cracking behavior of flawed sandstone specimens,and the fatigue failure pattern changes from shear-dominated failure with a transfixion shear band to tensile-dominated failure with massive tensile cracks as the F-T cycle number increases.Employing the scanning electron microscopy(SEM),the underlying damage mechanisms of flawed rocks under the coupling effect of F-T treatment and cyclic loading are discussed.Finally,an F-T-fatigue damage model is proposed based on FHP evolution and irreversible strain,which possesses distinct physical significance and reasonably quantifies the F-T deterioration and fatigue damage accumulation of flawed rocks.
基金Project(52401064)supported by the National Natural Science Foundation of ChinaProject(24B0172)supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProject(XDCX2024Y273)supported by the Postgraduate Scientific Research Innovation Project of Xiangtan University,China。
文摘Zn-Mn alloys are regarded as promising biodegradable metals for orthopedic applications owing to their moderate degradation rates and favorable osteogenic properties.However,the presence of a substantial number of second-phase particles in Zn-based alloys might induce severe localized degradation via micro-coupling corrosion,thereby compromising the mechanical integrity of the alloy during in vivo tissue regeneration.In this study,high pressure solid solution(HPSS)treatment was conducted at 5 GPa and 380℃ for 1 h to fabricate Zn-0.5 Mn alloys.Microstructural characterization revealed that the HPSS treatment facilitated the formation of a supersaturated solid solution by completely dissolving theζ-MnZn_(13) phase into theα-Zn matrix.The resultant strengthening mechanisms,including supersaturated solid solution strengthening,grain-size strengthening,and dislocation strengthening,collectively enhanced the compressive yield strength(σ_(cys))of the Zn-0.5 Mn alloy to about 183.7 MPa,approximately three times that of the as-cast(AC)Zn-0.5 Mn alloy.Moreover,compared with the AC alloy,the HPSS Zn-0.5 Mn alloy exhibited uniform degradation behavior with a markedly reduced degradation rate.
