期刊文献+
共找到23,016篇文章
< 1 2 250 >
每页显示 20 50 100
Experimental study on stress-permeability evolution of rocks under complex mining-induced loading:Insights into water inrush risk in floor strata
1
作者 Jinghua Li Guichen Li +4 位作者 Lei Zhang Kaijun Miao Xiaofang Wo Yingqi Yuan Zhongwei Chen 《International Journal of Mining Science and Technology》 2026年第2期333-351,共19页
Water inrush hazards from the floor strata of longwall workingface are commonly encountered in North China coalfields,which essentially result from the evolution of permeability in the floor rock under complex mining-... Water inrush hazards from the floor strata of longwall workingface are commonly encountered in North China coalfields,which essentially result from the evolution of permeability in the floor rock under complex mining-induced stress conditions.Current research rarely addresses the evolution of rock permeability under such complex stress paths.Describing this evolution using only one stress parameter,such as effective stress,deviatoric stress,axial stress,or confining stress,is highly challenging.In this study,we developed a laboratory loading scheme that simulates mining-induced stress evolution.Hydro-mechanical experiments were conducted to investigate the evolution of rock permeability under mining stress.The mechanism on the change of stress-permeability relationships in mining-disturbed rock is revealed,supporting to the analysis of management strategies for floor water-inrush disasters.The results show that rock permeability evolves through four stages,including rapid decline,gradual fluctuation,sharp increase,and slow attenuation.1–2 permeability surges occurred during mining-stress loading,closely linked to the emergence and reversal of deviatoric stress in magnitude and direction.With the first permeability surge,the deviatoric stress within the mudstone reached approximately 1.7 MPa,whereas that of the sandstone was about 1 MPa.The second permeability surge in the mudstone corresponded to the secondary rotation of the principal stress direction.CT and ultrasonic tests suggested an increase in microcracks in both rocks during the first permeability surge.However,the deviatoric stress-permeability plot before and after mining indicated that the fracture of mudstone sample changed significantly,while that of the sandstone remained unchanged.The permeability surges observed at different stages are interpreted as resulting from shear-induced reopening of pre-existing fractures and the formation of new shear-failure fractures.A stress-permeability model jointly governed by effective mean stress and deviatoric stress was established.Furthermore,two strategies are proposed for the floor water-inrush disasters prevention,(i)timely backfilling to reduce deviatoric stress,(ii)grouting after the first permeability surge.This work provides insights into stress-seepage behavior in rocks under complex stress evolution and offers new perspectives for identifying potential water inrush pathways in the floor strata of coal seam during longwall mining. 展开更多
关键词 STRESS PERMEABILITY Mining-disturbed Hydro-mechanical tests Workingface floor
在线阅读 下载PDF
Experimental Study of Solar-Powered Underfloor Heating in a Defined Space
2
作者 Firas Mahmood Younis Omar Mohammad Hamdoon Ayad Younis Abdulla 《Energy Engineering》 2026年第2期436-450,共15页
This paper presents an experimental analysis of a solar-assisted powered underfloor heating system,designed primarily to boost energy efficiency and achieve reliable desired steady-state temperature in buildings.We th... This paper presents an experimental analysis of a solar-assisted powered underfloor heating system,designed primarily to boost energy efficiency and achieve reliable desired steady-state temperature in buildings.We thoroughly tested the system’s thermal and operational features by subjecting it to three distinct scenarios that mimicked diverse solar irradiance and environmental conditions.Our findings reveal a strong correlation between variations in solar input and overall system performance.The Solar Fraction(SF),our key energy efficiency metric,varied significantly across the cases,ranging from 63.1%up to 88.7%.This high reliance on renewables resulted in a substantial reduction in backup power;consequently,the auxiliary electric heater was only required to supply between 1.82 and 3.00 kWh over the test periods.The circulation pump operated on a precise control logic,engaging below 20℃ and disengaging at 21℃.Crucially,the experiments verified the system’s ability not only tomeet the air temperature setpoint but also to ensure the floor surface temperature stayed within required international comfort criteria.These robust results directly support the study’s main objective.For practical application,we advise increasing the total length of the embedded pipe network.This crucial adjustment would allow for a reduction in the required circulating water temperature,which in turn maximizes the utilization of low-grade solar heat and optimizes radiant heat delivery toward achieving the desired steady-state temperature.Ultimately,the study confirms that solar-assisted underfloor heating offers a technically viable,sustainable,and energy-efficient solution with the potential to significantly cut fossil fuel consumption. 展开更多
关键词 Heat storage hydronic system radiant floor solar energy underfloor heating
在线阅读 下载PDF
Efficacy of vaginal androgen combined with pelvic floor muscle training for stress urinary incontinence in postmenopausal women:a randomized-controlled trial
3
作者 Yingxiu Chen Zhongyu Ren +1 位作者 Jiasheng Yan Yang Yu 《The Canadian Journal of Urology》 2026年第1期143-154,共12页
Objectives:Postmenopausal women with stress urinary incontinence(SUI)exhibit low androgen expression.This study aimed to evaluate the efficacy and safety of vaginal androgen combined with pelvic floor muscle training(... Objectives:Postmenopausal women with stress urinary incontinence(SUI)exhibit low androgen expression.This study aimed to evaluate the efficacy and safety of vaginal androgen combined with pelvic floor muscle training(PFMT)in the treatment of SUI in postmenopausal women.Methods:Postmenopausal women with SUI were recruited from Hainan West Central Hospital between January 2024 and March 2025.Participants were randomly assigned in a double-blind manner to receive either vaginal androgen cream combined with PFMT(treatment group)or a visually identical placebo cream(without androgens)combined with PFMT(control group).The vaginal cream was applied to the vaginal wall at a dose of 0.5 g per application,twice weekly for a total of 10 applications,while PFMT was conducted for 8 weeks.The clinical efficacy and safety were compared between the two groups.Results:A total of 61 patients were finally enrolled,with 31 in the treatment group and 30 in the control group.At both 3-month and 6-month follow-ups,the treatment group demonstrated significantly lower values in daily pad usage(p<0.05),24-h pad test scores(p<0.05),and ICIQ-UI SF scores(p<0.05)compared to the control group.The improvement rate of urinary incontinence was significantly higher in the treatment group(p<0.05).Compared to baseline,the treatment group showed statistically significant reductions in all three outcome measures(all p<0.05).No severe adverse events were reported in either group during the treatment period.Conclusions:Androgen therapy combined with PFMT significantly improved the urinary incontinence remission rate in postmenopausal women with SUI,with no severe adverse effects observed.These findings suggest that androgen therapy may represent a novel therapeutic approach for SUI management in postmenopausal women. 展开更多
关键词 ANDROGEN pelvic floor muscle training MENOPAUSE stress urinary incontinence WOMEN
暂未订购
Novel Statistical Shape Relation and Prediction of Personalized Female Pelvis,Pelvic Floor,and Perineal Muscle Shapes
4
作者 Tan-Nhu Nguyen Trong-Pham Nguyen-Huu Tien-Tuan Dao 《Computer Modeling in Engineering & Sciences》 2026年第2期1-47,共47页
Vaginal delivery is a fascinating physiological process,but also a high-risk process.Up to 85%–90%of vaginal deliveries lead to perineal trauma,with nearly 11%of severe perineal tearing.It is a common occurrence,espe... Vaginal delivery is a fascinating physiological process,but also a high-risk process.Up to 85%–90%of vaginal deliveries lead to perineal trauma,with nearly 11%of severe perineal tearing.It is a common occurrence,especially for first-time mothers.Computational childbirth plays an essential role in the prediction and prevention of these traumas,but fast personalization of the pelvis and floor muscles is challenging due to their anatomical complexity.This study introduces a novel shape-prediction-based personalization of the pelvis and floor muscles for perineal tearing management and childbirth simulation.300 subjects were selected from public Computed Tomography(CT)databases.The pelvic bone nmjmeshes were generated using a coarse-to-fine non-rigid mesh alignment procedure.The floor muscle meshes were personalized using the bone mesh deformation information.A feature-to-pelvic structure reconstruction pipeline was proposed,incorporating various strategies.Ten-fold cross-validation helped determine the optimal reconstruction strategy,regression method,and feature sizes.The mesh-to-mesh distance metric was employed for evaluating.The statistical shape relation-based strategy,coupled with multi-output ridge regression,was the optimal approach for pelvic structure reconstruction.With a feature set ranging from 3 to 38,the mean errors were 2.672 to 1.613 mm,and 3.237 to 1.415 mm in muscle attachment regions.The best-and worst-case predictions had errors of 1.227±0.959 mm and 2.900±2.309 mm,respectively.This study provides a novel approach to achieving fast personalized childbirth modeling and simulation for perineal tearing management. 展开更多
关键词 Personalized statistical shape relation shape prediction female pelvis shape pelvic floor and perineal tissue shape
暂未订购
Pelvic floor dysfunction in patients with gestational diabetes mellitus 被引量:2
5
作者 Mustafa Arslan Ramazan Kozan 《World Journal of Diabetes》 2025年第2期1-4,共4页
In this editorial,we comment on an article by Wang et al.Recent literature shows an increase in research on pelvic organ prolapse(POP).Although the true incidence of POP remains uncertain,its impact on quality of life... In this editorial,we comment on an article by Wang et al.Recent literature shows an increase in research on pelvic organ prolapse(POP).Although the true incidence of POP remains uncertain,its impact on quality of life is substantial.Anatomical studies report high incidence rates,surpassing those observed in symptom-based surveys.Weakness of the endopelvic fascia is a primary anatomical risk factor for POP.Additionally,gestational diabetes mellitus(GDM)has emerged as a growing concern,as poor glycemic control increases complications for both mother and fetus.GDM and POP are interconnected,with factors like maternal obesity,macrosomia,and hormonal changes exacerbating pelvic floor dysfunction.Modifiable risk factors,such as obesity and chronic hyperglycemia,along with multiparity,instrumental deliveries,and obstetric trauma,further increase susceptibility.For patients with GDM,gynecological exams,Pelvic Organ Prolapse Quantification staging,and pelvic floor ultrasonography are valuable diagnostics,with proctological exams and magnetic resonance defecography aiding in multi-compartment prolapse diagnoses.Imaging,though uncomfortable during pregnancy,is safe in the early postpartum period.This editorial emphasizes the need for further research on the pathophysiology of GDM-related POP and offers recommendations for improving diagnosis and clinical management of patients with GDM. 展开更多
关键词 DEFECOGRAPHY Chronic hyperglycemia Gestational diabetes mellitus MULTIPARITY Pelvic floor ultrasonography Pelvic organ prolapse OBESITY
暂未订购
Additional benefits of pelvic floor proprioceptive training combined with conventional therapy in the treatment of female stress urinary incontinence
6
作者 ZHANG Xiulan ZHU Liping +5 位作者 ZENG Xiaoling LIU Zhaoxue YANG Shuo ZHANG Hong YAN Wenguang LI Xuhong 《中南大学学报(医学版)》 北大核心 2025年第8期1385-1397,共13页
Objective:Stress urinary incontinence(SUI)is a common condition among women that severely impairs quality of life.Pelvic floor proprioceptive training(PFPT)has attracted increasing attention for its potential to enhan... Objective:Stress urinary incontinence(SUI)is a common condition among women that severely impairs quality of life.Pelvic floor proprioceptive training(PFPT)has attracted increasing attention for its potential to enhance pelvic floor muscle function and alleviate SUI symptoms.This study aims to observe and compare the clinical efficacy of PFPT combined with electroacupuncture,electrical stimulation,and biofeedback therapy versus conventional therapy consisting of electroacupuncture,electrical stimulation,and biofeedback alone in women with SUI,and to explore the role of PFPT in improving symptom and functional outcomes.Methods:In this randomized controlled trial,72 women with mild to moderate SUI were recruited from the Department of Rehabilitation Medicine at Third Xiangya Hospital,Central South University,between December 2021 and October 2023.Participants were randomly assigned to an experimental group(n=36)or a control group(n=36).Both groups received health education.The control group underwent electroacupuncture combined with electrical stimulation and biofeedback therapy,while the experimental group additionally received PFPT 3 times per week for 4 weeks.The primary outcome was assessed using the International Consultation on Incontinence Questionnaire-Short Form(ICIQ-SF).Secondary outcomes included pelvic floor muscle strength,bladder neck mobility,and balance ability.The ICIQ-SF was reassessed at 1,3,6,and 12 months post-treatment.Results:Both groups showed statistically significant improvements in all parameters after treatment(all P<0.05).However,there were no statistically significant differences between groups in most measures(all P>0.05).The experimental group demonstrated longer singleleg stance duration with eyes closed than the control group(left leg:P=0.026;right leg:P=0.006),with a significant increase from baseline(P<0.001).At 6 months post-treatment,the cure rate in the experimental group was significantly higher than that in the control group(P=0.037).Conclusion:Conventional therapy effectively improves SUI symptoms,but adding PFPT provides notable additional benefits,including enhanced balance ability and sustained midterm cure rates.These findings suggest that PFPT is a valuable adjunct to standard SUI management strategies. 展开更多
关键词 stress urinary incontinence pelvic floor proprioceptive training ELECTROACUPUNCTURE pelvic floor electrical stimulation pelvic floor biofeedback
暂未订购
Fault-Induced Floor Water Inrush in Confined Aquifers under Mining Stress: Mechanisms and Prevention Technologies—A State-of-the-Art Review 被引量:1
7
作者 Zhengzheng Cao Fangxu Guo +5 位作者 Wenqiang Wang Feng Du Zhenhua Li Shuaiyang Zhang Qixuan Wang Yongzhi Zhai 《Fluid Dynamics & Materials Processing》 2025年第10期2419-2442,共24页
With the depletion of shallow mineral resources,mining operations are extending to greater depths and larger scales,increasing the risk of water inrush disasters,particularly from confined aquifers intersected by faul... With the depletion of shallow mineral resources,mining operations are extending to greater depths and larger scales,increasing the risk of water inrush disasters,particularly from confined aquifers intersected by faults.This paper reviews the current state of research on fault-induced water inrushes in mining faces,examining the damage characteristics and permeability of fractured floor rock,the mechanical behavior of faults under mining stress,and the mechanisms driving water inrush.Advances in prevention technologies,risk assessment,and prediction methods are also summarized.Research shows that damage evolution in fractured floor rock,coupled with fluid-solid interactions,provides the primary pathways for water inrush.Stress-seepage coupling in porous media plays a decisive role in determining inrush potential.Mining-induced stress redistribution can activate faults,with parameters such as dip angle and internal friction angle controlling stress evolution and slip.Critical triggers include the hydraulic connectivity among faults,aquifers,and mining-induced fracture networks,followed by hydraulic erosion.A multi-pronged prevention framework has been developed,integrating precise fault detection,targeted grouting for water sealing,drainage to reduce water pressure,optimized waterproof coal pillar design,and dynamic risk assessment and prediction.However,gaps remain in understanding multi-physical field coupling under deep mining conditions,establishing quantitative criteria for fault activation-induced water inrush,and refining control technologies.Future work should focus on multi-scale numerical simulations,advanced active control measures,and intelligent,integrated prevention systems to clarify the mechanisms of fault-induced water inrush and enhance theoretical and technical support for mine safety. 展开更多
关键词 Water inrush mechanisms FAULTS floor strata damage and failure prevention and control technologies
在线阅读 下载PDF
Sinicization and psychometric validation of the German Pelvic Floor Questionnaire for Pregnant and Postpartum Women
8
作者 ZHU Liping ZHOU Chengyu +2 位作者 LI Xuhong HOU Qiao YANG Shuo 《中南大学学报(医学版)》 北大核心 2025年第1期72-80,共9页
Objective:Pelvic floor dysfunction is common among pregnant and postpartum women and significantly impacts quality of life.This study aims to translate the German Pelvic Floor Questionnaire for Pregnant and Postpartum... Objective:Pelvic floor dysfunction is common among pregnant and postpartum women and significantly impacts quality of life.This study aims to translate the German Pelvic Floor Questionnaire for Pregnant and Postpartum Women into Chinese and to evaluate its reliability and validity in the Chinese population.Methods:The questionnaire was translated using the Brislin model.A cross-sectional study was conducted among pregnant and postpartum women to assess the content validity,construct validity,Cronbach’sαcoefficient,test-retest reliability,and split-half reliability of the Chinese version.Results:A total of 72 women were included,with 6.9% being pregnant and 93.1% postpartum;the age was(32.3±3.6)years.The Chinese version of the questionnaire contains 4 dimensions and 45 items.The content validity index of individual items ranged from 0.833 to 1.000,with a scale-level content validity index of 0.977 and intraclass correlation coefficients(ICCs)exceeding 0.90.The overall Cronbach’s α coefficient was 0.891,with subscale coefficients ranging from 0.732 to 0.884(all ICCs>0.70).The testretest reliability of the total scale was 0.833,and for the 4 dimensions,bladder,bowel,prolapse,and sexual function,the values were 0.776,0.579,0.732,and 0.645,respectively.The split-half reliability was 0.74.Conclusion:The Chinese version of the questionnaire demonstrated good reliability and validity,indicating its applicability in assessing pelvic floor dysfunction and associated risk factors during pregnancy and postpartum. 展开更多
关键词 pelvic floor dysfunction PREGNANCY postpartum women QUESTIONNAIRE RELIABILITY validity
暂未订购
Research on the design floor response spectrum of buildings by dynamic analysis
9
作者 Liu Rongheng Bai Wen +3 位作者 Dai Junwu Shao Zhipeng Jiang Tao Zhao Bingzhang 《Earthquake Engineering and Engineering Vibration》 2025年第2期413-436,共24页
The seismic design forces of nonstructural components(NSCs)in buildings are closely related to floor acceleration response amplification.To investigate the differences in acceleration responses of structures with diff... The seismic design forces of nonstructural components(NSCs)in buildings are closely related to floor acceleration response amplification.To investigate the differences in acceleration responses of structures with different structural types,fundamental periods,and seismic design levels,56 reinforced concrete and steel structures with fundamental periods ranging from 0.37 s to 5.68 s were selected.For each structure,100 sets of earthquake motions were used as inputs for elastic time history analysis.Based on the resulting 26,500 sets of floor acceleration response data,the amplification rules of peak floor acceleration/peak ground acceleration(PFA/PGA)along the height of various structures and the corresponding floor response spectrum characteristics were studied.The nonlinear changes of PFA/PGA along the height of long period structures were compared with the codes of different countries.Moreover,more suitable prediction equations were proposed based on the structural characteristics.Finally,to solve the issue that existing research still cannot accurately reflect the acceleration amplification coefficient of NSCs with different dynamic characteristics in main structures with different periods,a normalized floor response spectrum is proposed that can simultaneously consider the effects of input ground motion characteristics and the main structure,which can be better used in the seismic design of NSCs. 展开更多
关键词 floor acceleration amplification factor nonstructural components component amplification factor seismic design floor response spectrum
在线阅读 下载PDF
What's on Each Floor?
10
作者 Maria Chiu 《空中英语教室(初级版.大家说英语)》 2025年第6期34-35,54,共3页
Conversation A(in a department store)Sara:Department store directories are helpful.Sam:They are.Today,I have to buy new furniture and bedding for my apartment.They're on the sixth floor.
关键词 BEDDING FURNITURE department store store directories floor
原文传递
Individualized pelvic floor rehabilitation training on psychological and functional recovery in postpartum women with generalized anxiety disorder
11
作者 Cong-Ying Zhao Shu-Qing Han +1 位作者 Xian-Chai Peng Zhen-Hong Liu 《World Journal of Psychiatry》 2025年第6期118-127,共10页
BACKGROUND Postpartum women are at an increased risk of generalized anxiety disorder(GAD),which can negatively affect both mental health and physical recovery.Pelvic floor dysfunction,common in this population,can exa... BACKGROUND Postpartum women are at an increased risk of generalized anxiety disorder(GAD),which can negatively affect both mental health and physical recovery.Pelvic floor dysfunction,common in this population,can exacerbate psychological distress.Although pelvic floor rehabilitation is effective in physical recovery,its potential to improve psychological outcomes,especially in women with GAD,remains underexplored.AIM To evaluate the effectiveness of an individualized pelvic floor rehabilitation program in improving anxiety,pelvic floor function,and quality of life in postpartum women with GAD.METHODS A retrospective study was performed to analyze 80 postpartum women with GAD who completed a 12-week individualized pelvic floor rehabilitation program(January 2020-December 2024),combining supervised pelvic floor muscle training and psychological support.Primary outcomes were changes in GAD-7 and Hamilton anxiety rating scale(HAM-A)scores and pelvic floor function measured by surface electromyography(sEMG).Secondary outcomes included World Health Organization quality of life-BREF,pelvic floor symptom severity,and impact on daily activities(pelvic floor impact questionnaire).Assessments were conducted at baseline and 6 and 12 weeks during the intervention period.RESULTS Significant improvements were observed in anxiety measures,with mean GAD-7 scores decreasing from 14.8±3.2 at baseline to 8.2±2.9 at week 12(P<0.001)and HAM-A scores decreasing from 22.6±4.5 to 12.4±3.8(P<0.001).Pelvic floor function showed substantial enhancement,with sEMG amplitude increasing from 22.4±5.6μV to 35.9±6.8μV(P<0.001).Quality of life improved across all domains,with the most significant improvements in psychological(28.5%increase)and physical health(25.8%increase).Program adherence was 91.5%for the supervised sessions,and no serious adverse events were reported.CONCLUSION Individualized pelvic floor rehabilitation training effectively improves both psychological and functional outcomes in postpartum women with GAD.The high adherence and significant outcomes make this integrated approach feasible and effective. 展开更多
关键词 Generalized anxiety disorder Pelvic floor rehabilitation Postpartum care Physical therapy Mental health
暂未订购
Pelvic Floor Dysfunction Databases:Evolution,Current Landscape,and Future Development
12
作者 Jing-Yu Zhang An-Ran Wang +3 位作者 Shuo Liang Hong-Hui Shi Lan Zhu Si-Zhu Wu 《Chinese Medical Sciences Journal》 2025年第4期295-308,I0004,共15页
Pelvic floor dysfunction(PFD),including conditions such as stress urinary incontinence,pelvic organ prolapse,and fecal incontinence,significantly affects women's quality of life and their physical and mental healt... Pelvic floor dysfunction(PFD),including conditions such as stress urinary incontinence,pelvic organ prolapse,and fecal incontinence,significantly affects women's quality of life and their physical and mental health.With advancement of digital medicine,the systematic collection of data and the high-quality development of database platforms have increasingly become central pillars of PFD research and management.We systematically review the developmental stages of PFDrelated databases.We then conduct a comparative analysis of representative international and domestic platforms,examining key aspects including organizational structures and construction models,data sources and integration strategies,core functionalities,data quality control and standardization,data security and access management,and research applications.Finally,based on the current status of PFD database development both globally and in China,we offer recommendations to strengthen data infrastructure and guide future directions.The findings may serve as a valuable reference for the optimization of PFD databases worldwide. 展开更多
关键词 pelvic floor dysfunction disease registry DATABASE data platform disease research
暂未订购
Effect of snow cover and soil temperature on tree and forest floor processes:a case study in mature boreal forest
13
作者 Lauri Lindfors Vilma Ylilauri +10 位作者 Jie Xu Pekka Kaitaniemi Alessandro Zanetti Magdalena Held Juho Aalto Pauliina Schiestl‑Aalto Kira Ryhti‑Laine Vicent Ribas‑Costa Yann Salmon Jussi Heinonsalo Anna Lintunen 《Journal of Forestry Research》 2025年第6期45-67,共23页
The duration of snow cover has shortened in the boreal region,and the amount of seasonal snow decreased.This affects the coupling between soil and air temperatures and may thus lead to colder soil and deeper soil fros... The duration of snow cover has shortened in the boreal region,and the amount of seasonal snow decreased.This affects the coupling between soil and air temperatures and may thus lead to colder soil and deeper soil frost.We prevented snow reaching the forest floor for two winters in mature boreal forest and studied how that affects tree and forest floor processes.The studied species were Scots pine,Norway spruce,silver birch,and a dwarf shrub bilberry.Decreased soil temperature,due to the lack of snow cover,decreased forest floor respiration in winter and spring.Simultaneously,response of respiration to temperature seemed to increase,perhaps due to the exposure of forest floor vegetation to cold air temperature.Indeed,lack of snow cover induced mortality of bilberry,but the remaining ramets grew more in height and their average leaf size was larger likely to compensate for the lost plant biomass.Lack of snow cover also affected tree hydraulics as tree water uptake was decreased in spring,and the start of the sap season delayed in birch.Pine and birch tended to grow less in the snow exclusion treatment(differences not statistically significant),whereas spruce grew more.Coarse root traits,e.g.water content and cellular frost damages,were not affected by the snow exclusion treatment.The results of this case study increase our understanding on the effects of changing snow cover on spring-time tree and forest floor processes in mature boreal forest,but also reveal the need for further studies on mature trees. 展开更多
关键词 Dwarf shrubs Fine roots Forest floor respiration Snow cover change Tree hydraulics
在线阅读 下载PDF
Research on Design Method of Dynamic Shop Floor Scheduling System Based on Human-computer Interaction
14
作者 Songling TIAN Zhuke CAI +1 位作者 Xiaoqiang WU Xiaoqian QI 《Mechanical Engineering Science》 2025年第2期17-26,共10页
The shop floor dynamic scheduling system based on human-computer interaction is the use of computer-aided decision-making and human-computer interaction to solve the dynamic scheduling problem.A human-computer interac... The shop floor dynamic scheduling system based on human-computer interaction is the use of computer-aided decision-making and human-computer interaction to solve the dynamic scheduling problem.A human-computer interaction interface based on Gantt chart is designed,which can not only comprehensively and quantitatively represent the scheduling process and scheduling scheme,but also have friendly human-computer interaction performance.The data transmission and interaction architecture is constructed to realize the rapid response to shop floor disturbance events.A priority calculation algorithm integrating priority rules and dispatcher preference is proposed,which realizes the automatic calculation of priority for the dispatcher's reference and reduces theirburden.A man-machine interactive shop floor dynamic scheduling strategy is proposed.When solving the dynamic flexible job shop scheduling problem caused by machine tool breakdown and urgent order,the origin moments obtained by using this strategy are 0.4190 and 0.3703 respectively.As can be seen from the origin moment indicator,the dynamic shop floor scheduling system based on the human-computer interaction is efficient and reliable in solving dynamic scheduling problems,and related strategies of this system are also feasible and stable. 展开更多
关键词 Human-computer interaction Dynamic scheduling Flexible shop floor scheduling Perturbation events
在线阅读 下载PDF
Long-term floor heave analysis of loess tunnel based on modified Green-Ampt infiltration model
15
作者 CHANG Zhou YAN Changgen +2 位作者 YIN Peijie LAN Hengxing BAO Han 《Journal of Mountain Science》 2025年第12期4574-4594,共21页
Floor heave is a common water-induced issue of loess tunnels.However,the mechanism of tunnel floor heave induced by repeated rainfall or irrigation remains poorly understood.This study analyzes moisture variation at t... Floor heave is a common water-induced issue of loess tunnels.However,the mechanism of tunnel floor heave induced by repeated rainfall or irrigation remains poorly understood.This study analyzes moisture variation at the tunnel base and invert deformation through a 15-year survey of an operational loess tunnel.An improved Green-Ampt model was developed to capture the effects of interannual repeated infiltration on water content,permeability,and matric suction at the tunnel base.The model was validated using soil column infiltration tests.The calculated wetting front depth was incorporated into the tunnel numerical simulation to analyze the development of floor heave and assess its several influencing factors.Results show the base average water content at the tunnel base increases exponentially with operational years.After 15 years,over 50%of the monitored sections reach saturation,leading to significant invert uplift.Based on the plastic limit,saturation water content,and liquid limit of loess,floor heave is categorized into four levels with deformation thresholds at 10,25,and 50 mm.The modified Green-Ampt model is suitable for repeated infiltration conditions and offers practical guidance.Neglecting hydraulic deterioration due to repeated infiltration may lead to significant prediction errors.Numerical simulations reveal that the inverted arch uplift height,width,and height-to-width ratio increase linearly with the rise in the number of infiltration events.The uplift deformation follows Gaussian distribution in both cross and longitudinal sections,forming aΛ-shaped floor heave.The influence of infiltration duration,water content,horizontal infiltration,asymmetric infiltration,burial depth,and the number of infiltration events enhanced successively on floor heave.This model facilitates the prediction of floor heave under dynamic hydrological conditions during long-term tunnel operation. 展开更多
关键词 Loess tunnel floor heave Green-Ampt model Repeated infiltration Sensitivity analysis Loess Plateau
原文传递
Predicting floor heave risk in road tunnels with machine learning
16
作者 Xuefeng Ou Ye Zhou +5 位作者 Yong Kong Tongming Qu Shiquan Xu Wei Liao Cong Tang Xuemin Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第10期6428-6438,共11页
Floor heave is a common defect in mountainous tunnels.It is critical but challenging to predict the risk of floor heave,as traditional methods often fail to characterize this phenomenon effectively.This study proposes... Floor heave is a common defect in mountainous tunnels.It is critical but challenging to predict the risk of floor heave,as traditional methods often fail to characterize this phenomenon effectively.This study proposes a data-driven approach utilizing a support vector machine(SVM)optimized by the sparrow search algorithm(SSA)to address the issue.The model was developed and validated using a dataset collected from 100 tunnels.Shapley value analysis was conducted to identify the key features influencing floor heave defects.Moreover,a committee-based uncertainty quantification method is presented to evaluate the reliability of each prediction.The results show that:(1)Data feature engineering and SSA play pivotal roles in expediting the convergence of the SVM model.(2)Groundwater and high in situ stress are key factors contributing to tunnel floor heave.(3)In comparison to backpropagation(BP)neural networks,the SSA-SVM demonstrates superior robustness in handling imperfect and limited data.(4)The committee-based uncertainty quantification method is proven effective to evaluate the trustworthiness of each prediction.This data-driven surrogate model offers an effective strategy for understanding the factors that impact tunnel floor defects and accurately predicting tunnel floor heave deformation. 展开更多
关键词 floor heave Support vector machine(SVM) Sparrow search algorithm(SSA) Shapley value Uncertainty quantification
在线阅读 下载PDF
Numerical and Experimental Study of Thermal Storage Energy in a Building with Various Pipeline Design under Floor—Case Study
17
作者 Rafah H.Zaidan Najim A.Jasim 《Frontiers in Heat and Mass Transfer》 2025年第5期1595-1620,共26页
This paper presents a comprehensive experimental and numerical investigation of radiant floor heating(RFH)systems integrated with phase changematerial(PCM)-based thermal energy storage(TES).The study compares two unde... This paper presents a comprehensive experimental and numerical investigation of radiant floor heating(RFH)systems integrated with phase changematerial(PCM)-based thermal energy storage(TES).The study compares two underfloor pipe configurations:double serpentine and spiral.It also looks at how well a paraffin wax PCM system works with compact heat exchanger-type TES units during winter in Iraq.Key performance indicators including discharge temperature,heat transfer rate,liquid fraction evolution,and temperature uniformity were assessed through in situ experimental measurements and ANSYS fluent simulations.Results demonstrate that the spiral design provides slightly more uniform temperature distribution on the tile surface at an inlet water temperature of 55℃,with an average difference of approximately 0.5%,the serpentine layout exhibits higher slab temperature distribution by about 0.66%.Notably,the serpentine configuration shows superior thermal homogeneity and heat distribution,with a 15.05%increase in heat gain at a 55℃ inlet temperature compared to the spiral design.The performance gap between the two layouts narrows as the inlet temperature increases from 50℃ in 5℃ increments by approximately 4.1%,3.7%,and 1.7%,respectively.Higher inlet temperatures also improve PCM discharging and charging rates,improving energy storage utilization.The findings provide significant design guidelines for sustainable heating systems for cold climates. 展开更多
关键词 Radiant floor heating systems phase change materials(PCM) paraffin wax thermal energy storage experimental invistagation numerical thermal energy
在线阅读 下载PDF
木地板紫外激光标刻加工工艺研究
18
作者 彭晓瑞 侯晓鹏 +3 位作者 孟凡丹 唐召群 王霄 张玲 《林业工程学报》 北大核心 2026年第1期180-188,共9页
木地板生产全流程数据采集与追踪是实现敏捷制造转型升级的大势所趋,采用激光标刻二维码方法可为木地板生产数据采集、交互与质量追溯提供条件。355 nm超快紫外激光具有窄的脉冲宽度和高的单脉冲能量,以及加工热效应小、精度高、标刻速... 木地板生产全流程数据采集与追踪是实现敏捷制造转型升级的大势所趋,采用激光标刻二维码方法可为木地板生产数据采集、交互与质量追溯提供条件。355 nm超快紫外激光具有窄的脉冲宽度和高的单脉冲能量,以及加工热效应小、精度高、标刻速度快等优点。通过对木地板表面进行皮秒超快紫外激光标刻试验,研究了超快紫外激光功率、激光扫描速度及激光束的离焦量、线间距等对木地板表面激光标刻深度、微观形貌和图像平均对比度的影响,得出功率5~7 W、激光扫描速度900~1200 mm/s、激光束离焦量0~2 mm、线间距0.02 mm条件下,木地板表面标刻深度相对适中。结合木材表面标刻后的颜色、深度和平均对比度等评价指标,紫外激光标刻木地板的优化工艺参数为功率5 W、激光扫描速度900 mm/s、离焦量1 mm、线间距0.02 mm,此工艺条件有利于数据采集与二维码的标刻与识读。本研究初探得到激光功率5 W、线间距0.03 mm的不同扫描速度试验条件下,激光标刻二维码的标刻时间可低至3 s,可识读性较好。本研究为紫外激光标刻在木材工业产品质量溯源与智能制造等方面的应用提供了一定的技术基础。 展开更多
关键词 紫外激光 木地板 标刻 加工工艺
在线阅读 下载PDF
盆底超声参数及盆底肌电生理参数与高龄产妇产后盆底功能障碍严重程度的相关研究
19
作者 黄梅 马爱玲 +3 位作者 冯娜娜 王书伟 朱丽 苏洁 《临床和实验医学杂志》 2026年第1期105-110,共6页
目的探讨盆底超声参数及盆底肌电生理参数与高龄产妇产后盆底功能障碍(PFD)严重程度的相关性。方法前瞻性选取2023年3月至2025年6月在河北省沧州中西医结合医院分娩的156例初产妇,根据产后42 d是否出现PFD将产妇分为两组,将发生PFD的产... 目的探讨盆底超声参数及盆底肌电生理参数与高龄产妇产后盆底功能障碍(PFD)严重程度的相关性。方法前瞻性选取2023年3月至2025年6月在河北省沧州中西医结合医院分娩的156例初产妇,根据产后42 d是否出现PFD将产妇分为两组,将发生PFD的产妇作为观察组(n=106),未发生PFD的产妇作为对照组(n=50),并进一步根据国际通用盆腔器官脱垂定量分期法(POP-Q)将观察组产妇分为轻度组(n=39)、中度组(n=37)、重度组(n=30)。比较两组产妇及观察组3个亚组产妇的盆底超声参数[静息、最大Valsalva状态下尿道倾斜角(UTA)、膀胱颈位置(BNP)、膀胱颈移动度(BND)、尿道膀胱后角(PUA)、尿道旋转角(URA)、肛提肌裂孔面积]及盆底肌电生理参数(前基线/后基线平静期电位平均值、Ⅰ类/Ⅱ类肌纤维收缩期电位平均值、Ⅰ类/Ⅱ类肌纤维收缩期时间),并分析其与PFD严重程度的相关性。结果观察组静息状态下UTA、PUA、肛提肌裂孔面积均高于对照组,差异均有统计学意义(P<0.05)。观察组最大Valsalva状态下UTA、BND、URA、PUA、肛提肌裂孔面积均高于对照组,观察组最大Valsalva状态下BNP低于对照组,差异均有统计学意义(P<0.05)。观察组Ⅱ类肌纤维收缩期电位平均值、Ⅰ类肌纤维收缩期电位平均值及Ⅱ类肌纤维收缩期时间均明显低于或短于对照组,差异均有统计学意义(P<0.05)。静息状态下UTA、PUA、肛提肌裂孔面积:重度组>中度组>轻度组,组间比较差异均有统计学意义(P<0.05);最大Valsalva状态下,UTA、BND、URA、PUA、肛提肌裂孔面积比较:重度组>中度组>轻度组,BNP比较:轻度组>中度组>重度组,组间比较差异均有统计学意义(P<0.05)。Ⅰ类、Ⅱ类肌纤维收缩期电位平均值、Ⅱ类肌纤维收缩期时间比较:轻度组>中度组>重度组,组间比较差异均有统计学意义(P<0.05)。盆底超声参数中,BNP与PFD严重程度呈显著负相关(P<0.05),而UTA、BND、URA、PUA及肛提肌裂孔面积等参数均与PFD严重程度呈显著正相关(均P<0.05)。盆底肌电生理参数中,Ⅰ类和Ⅱ类肌纤维的收缩期电位平均值及Ⅱ类肌纤维收缩期时间均与PFD严重程度呈显著负相关(均P<0.05)。结论盆底超声参数及盆底肌电生理参数与高龄产妇产后PFD严重程度存在显著相关性,临床可通过检查相关参数明确产后PFD严重程度并为后续诊疗提供可靠数据支持。 展开更多
关键词 盆底功能障碍 盆底超声 盆底肌电生理参数 严重程度 相关性
暂未订购
不同梁柱约束下混凝土楼盖火灾后承载力试验及理论研究
20
作者 王勇 王姗姗 +4 位作者 严宝峰 吁达 张亚军 张宝明 滕飞 《工程力学》 北大核心 2026年第2期71-88,共18页
为了研究梁柱约束和配筋方式等对混凝土楼盖灾后性能的影响,对4块灾后楼盖和2块常温楼盖开展力学性能试验,获得了楼盖裂缝发展、混凝土和钢筋应变、荷载-位移曲线、极限承载力和破坏模式等发展规律,并与其他文献试验结果进行对比分析。... 为了研究梁柱约束和配筋方式等对混凝土楼盖灾后性能的影响,对4块灾后楼盖和2块常温楼盖开展力学性能试验,获得了楼盖裂缝发展、混凝土和钢筋应变、荷载-位移曲线、极限承载力和破坏模式等发展规律,并与其他文献试验结果进行对比分析。基于简支椭圆方法,提出平面方程、位移比和四等分点等概念,考虑梁竖向位移、柱端约束和温度影响,建立混凝土楼盖修正屈服线荷载和极限承载力计算方法,并与相关计算方法进行对比分析。相比梁柱无竖向约束情况,增强梁柱竖向约束,可提高楼盖极限承载力约10%~30%;相比分离式配筋方式,双层双向配筋方式可减少裂缝数量,特别是板顶跨中区域,且可提高楼盖承载力约10%~20%。相比常温楼盖,灾后楼盖裂缝间距和宽度均较大,易发生局部冲切破坏。由于忽略梁板相互作用,传统屈服线理论和受拉薄膜效应方法计算结果偏于保守,而该文方法考虑梁柱约束作用和梁位移影响,计算结果较为合理。 展开更多
关键词 混凝土楼盖 梁柱约束 承载力 椭圆方法 破坏模式
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部