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
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
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
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.
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
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
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
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
BACKGROUND Pelvic floor dysfunction(PFD)is related to muscle fiber tearing during childbirth,negatively impacting postpartum quality of life of parturient.Appropriate and effective intervention is necessary to promote...BACKGROUND Pelvic floor dysfunction(PFD)is related to muscle fiber tearing during childbirth,negatively impacting postpartum quality of life of parturient.Appropriate and effective intervention is necessary to promote PFD recovery.AIM To analyze the use of hydrogen peroxide and silver ion disinfection for vaginal electrodes in conjunction with comprehensive rehabilitation therapy for postpartum women with PFD.METHODS A total of 59 women with PFD who were admitted to the hospital from May 2019 to July 2022 were divided into two groups:Control group(n=27)received comprehensive rehabilitation therapy and observation group(n=32)received intervention with pelvic floor biostimulation feedback instrument in addition to comprehensive rehabilitation therapy.The vaginal electrodes were disinfected with hydrogen peroxide and silver ion before treatment.Intervention for both groups was started 6 weeks postpartum,and rehabilitation lasted for 3 months.Pelvic floor muscle voltage,pelvic floor muscle strength,vaginal muscle voltage,vaginal muscle tone,pelvic floor function,quality of life,and incidence of postpartum PFD were compared between the two groups.RESULTS Before comprehensive rehabilitation treatment,basic data and pelvic floor function were not significantly different between the two groups.After treatment,the observation group showed significant improvements in the maximum voltage and average voltage of pelvic floor muscles,contraction time of type I and type II fibers,pelvic floor muscle strength,vaginal muscle tone,vaginal muscle voltage,and quality of life(GQOLI-74 reports),compared with the control group.The observation group had lower scores on the pelvic floor distress inventory(PFDI-20)and a lower incidence of postpartum PFD,indicating the effectiveness of the pelvic floor biostimulation feedback instrument in promoting the recovery of maternal pelvic floor function.CONCLUSION The combination of the pelvic floor biostimulation feedback instrument and comprehensive rehabilitation nursing can improve pelvic floor muscle strength,promote the recovery of vaginal muscle tone,and improve pelvic floor function and quality of life.The use of hydrogen peroxide and silver ion disinfectant demonstrated favorable antibacterial efficacy and is worthy of clinical application.展开更多
Objective:Pelvic floor sensory training is commonly used in clinical practice for the treatment of stress urinary incontinence(SUI);however,there is a lack of comparative studies evaluating pelvic floor sensation betw...Objective:Pelvic floor sensory training is commonly used in clinical practice for the treatment of stress urinary incontinence(SUI);however,there is a lack of comparative studies evaluating pelvic floor sensation between women with SUI and healthy controls.Additionally,normative data for two-point discrimination thresholds in the female pelvic floor region remain scarce.This study aims to compare the results of 4 sensory tests in the pelvic floor region between women with mild SUI and healthy women,in order to provide reference values for two-point discrimination thresholds in this area.Methods:From April 1 to October 30,2023,108 healthy women[(32.5±3.6)years]and 90 women with mild SUI[(32.9±3.3)years]were recruited from the Third Xiangya Hospital,Central South University.Participants underwent 4 sensory tests in the pelvic floor region:Two-dot discrimination,weight perception,shape recognition,and 9-grid localization.The results were compared between the 2 groups.Results:Compared with healthy women,those with mild SUI had lower sensitivity and higher thresholds in 2-dot discrimination tests in the pelvic floor region(all P<0.001).No significant differences were found between groups in weight perception,shape recognition,or grid localization tests(P>0.05).Conclusion:Women with mild stress urinary incontinence have impaired two-point discrimination ability in the pelvic floor region.展开更多
BACKGROUND Spastic pelvic floor syndrome(SPFS)is a refractory pelvic floor disease characterized by abnormal(uncoordinated)contractions of the external anal sphincter and puborectalis muscle during defecation,resultin...BACKGROUND Spastic pelvic floor syndrome(SPFS)is a refractory pelvic floor disease characterized by abnormal(uncoordinated)contractions of the external anal sphincter and puborectalis muscle during defecation,resulting in rectal emptation and obstructive constipation.The clinical manifestations of SPFS are mainly characterized by difficult defecation,often accompanied by a sense of anal blockage and drooping.Manual defecation is usually needed during defecation.From physical examination,it is commonly observed that the patient's anal muscle tension is high,and it is difficult or even impossible to enter with his fingers.AIM To investigate the characteristics of anorectal pressure and botulinum toxin A injection combined with biofeedback in treating pelvic floor muscle spasm syndrome.METHODS Retrospective analysis of 50 patients diagnosed with pelvic floor spasm syndrome.All patients underwent pelvic floor surface electromyography assessment,anorectal dynamics examination,botulinum toxin type A injection 100 U intramuscular injection,and two cycles of biofeedback therapy.RESULTS After the botulinum toxin A injection combined with two cycles of biofeedback therapy,the patient's postoperative resting and systolic blood pressure were significantly lower than before surgery(P<0.05).Moreover,the electromyography index of the patients in the resting stage and post-resting stages was significantly lower than before surgery(P<0.05).CONCLUSION Botulinum toxin A injection combined with biofeedback can significantly reduce pelvic floor muscle tension in treating pelvic floor muscle spasm syndrome.Anorectal manometry is an effective method to evaluate the efficacy of treatment objectively.However,randomized controlled trials are needed.展开更多
The Noise,Vibration,and Harshness(NVH)experience during driving is significantly influenced by the sound insulation performance of the car floor acoustic package.As such,accurate and efficient predictions of its sound...The Noise,Vibration,and Harshness(NVH)experience during driving is significantly influenced by the sound insulation performance of the car floor acoustic package.As such,accurate and efficient predictions of its sound insulation performance are crucial for optimizing related noise reduction designs.However,the complex acoustic transmission mechanisms and difficulties in characterizing the sound absorption and insulation properties of the floor acoustic package pose significant challenges to traditional Computer-Aided Engineering(CAE)methods,leading to low modeling efficiency and prediction accuracy.To address these limitations,a hierarchical multiobjective decomposition system for predicting the sound insulation performance of the floor acoustic package has been developed based on an analysis of the noise transmission path.This approach involves introducing a 1D-Convolutional Neural Network(1D-CNN)model for predicting the sound insulation performance of the floor acoustic package,thereby avoiding the limitations of conventional CAE approaches that rely solely on“data-driven”methods.The proposed method was applied and tested using specific vehicle models,and the results demonstrated the effectiveness and superiority of the proposed approach relative to those obtained using 2D-CNN and Support Vector Regression(SVR)models.展开更多
The presence of horizontal layered rocks in tunnel engineering significantly impacts the stability and strength of the surrounding rock mass,leading to floor heave in the tunnel.This study focused on preparing layered...The presence of horizontal layered rocks in tunnel engineering significantly impacts the stability and strength of the surrounding rock mass,leading to floor heave in the tunnel.This study focused on preparing layered specimens of rock-like material with varying thickness to investigate the failure behaviors of tunnel floors.The results indicate that thin-layered rock mass exhibits weak interlayer bonding,causing rock layers near the surface to buckle and break upwards when subjected to horizontal squeezing.With an increase in the layer thickness,a transition in failure mode occurs from upward buckling to shear failure along the plane,leading to a noticeable reduction in floor heave deformation.The primary cause of significant deformation in floor heave is upward buckling failure.To address this issue,the study proposes the installation of a partition wall in the middle of the floor to mitigate heave deformation of the rock layers.The results demonstrate that the partition wall has a considerable stabilizing effect on the floor,reducing the zone of buckling failure and minimizing floor heave deformation.It is crucial for the partition wall to be sufficiently high to prevent buckling failure and ensure stability.Through simulation calculations on an engineering example,it is confirmed that implementing a partition wall can effectively reduce floor heave and enhance the stability of tunnel floor.展开更多
With the increase of mining scope,rockburst occurs frequently,but its generation mechanism has not been understood comprehensively.Based on a rockburst in the coal pillar area of high tectonic stress zones(HTSZs),this...With the increase of mining scope,rockburst occurs frequently,but its generation mechanism has not been understood comprehensively.Based on a rockburst in the coal pillar area of high tectonic stress zones(HTSZs),this study analyzed the distribution characteristics of large-energy microseismic(MS)events by using data statistics.The mechanical cause of the MS event that induced the rockburst was revealed by means of seismic moment tensor inversion.On this basis,by using numerical simulation,this study explored the distribution characteristics of static load in rockburst area and the effect of dynamic load in the floor,and then proposed the rockburst mechanism.The results show that under the squeezing action,the floor strata in HTSZs implode and transmit energy outward in the form of stress waves.This causes the cumulative damage and stress of the coal body in the fast track of coal pillar area increase in a short time.Since the coal in this area has already been in the critical stress state,small stress changes may lead to coal failure and rockburst.In this case of rockburst,the high static load of coal is the main force source,and the dynamic load plays a role in increasing coal body damage and inducing rockburst.Combined with seismic moment tensor inversion and numerical simulation,this paper proposes a rockburst research scheme,which makes the simulation of dynamic load more reasonable.The results provide the theoretical basis for rockburst control under similar conditions.展开更多
Digital twin technology, originally developed for intricate physical systems, holds great potential in women’s healthcare, particularly in the management of pelvic floor disorders. This paper delves into the developm...Digital twin technology, originally developed for intricate physical systems, holds great potential in women’s healthcare, particularly in the management of pelvic floor disorders. This paper delves into the development of a digital twin specifically for the female pelvic floor, which can amalgamate various data sources such as imaging, biomechanical assessments, and patient-reported outcomes to offer personalized diagnostic and therapeutic insights. Through the utilization of 3D modeling and machine learning, the digital twin may facilitate precise visualization, prediction, and individualized treatment planning. Nevertheless, it is crucial to address the ethical and practical challenges related to data privacy and ensuring fair access. As this technology progresses, it has the potential to revolutionize gynecological and obstetric care by enhancing diagnostics, customizing treatments, and increasing patient involvement.展开更多
Recently the manufacture of epoxy coating and flooring materials begun to be under strong pressure to use more environmentally friendly raw materials in its composition.First tendency to reduce of solvents and diluent...Recently the manufacture of epoxy coating and flooring materials begun to be under strong pressure to use more environmentally friendly raw materials in its composition.First tendency to reduce of solvents and diluents contained in the materials appeared at the end of 90´s.This situation was supported by the Council of Europe in 2004 to reduce VOC emissions to zero till 2020.Solvent materials were thus largely replaced by solvent free materials from which the volatile substances are not released into the air.But pressure continued to increase,and over the past decade began to take centre stage water-based epoxy.On the Czech market solvent based material is still occasionally used,but predominant are solvent free materials.There are no commonly used materials containing wastes as fillers in new water-borne and solvent-free epoxy materials.Characteristics identification of the waste material as a potential filler is a set of properties that determine the limits of secondary raw materials or waste as a filler.This paper describes the basic characteristics which must be selected to meet the requirements,to affect negatively the workability,sedimentation,properties and behavior of the final floor system.Some materials must comply with special requirements,such as resistance to chemicals,etc.Next part of paper talks about utilization of polymer floors and their mechanical properties.展开更多
Machining is as old as humanity, and changes in temperature in both the machine’s internal and external environments can be of great concern as they affect the machine’s thermal stability and, thus, the machine’s d...Machining is as old as humanity, and changes in temperature in both the machine’s internal and external environments can be of great concern as they affect the machine’s thermal stability and, thus, the machine’s dimensional accuracy. This paper is a continuation of our earlier work, which aimed to analyze the effect of the internal temperature of a machine tool as the machine is put into operation and vary the external temperature, the machine floor temperature. Some experiments are carried out under controlled conditions to study how machine tool components get heated up and how this heating up affects the machine’s accuracy due to thermally induced deviations. Additionally, another angle is added by varying the machine floor temperature. The parameters mentioned above are explored in line with the overall thermal stability of the machine tool and its dimensional accuracy. A Robodrill CNC machine tool is used. The CNC was first soaked with thermal energy by gradually raising the machine floor temperature to a certain level before putting the machine in operation. The machine was monitored, and analytical methods were deplored to evaluate thermal stability. Secondly, the machine was run idle for some time under raised floor temperature before it was put into operation. Data was also collected and analyzed. It is observed that machine thermal stability can be achieved in several ways depending on how the above parameters are joggled. This paper, in conclusion, reinforces the idea of machine tool warm-up process in conjunction with a carefully analyzed and established machine floor temperature variation for the approximation of the machine tool’s thermally stability to map the long-time behavior of the machine tool.展开更多
Gateways at faces of great mining heights are mostly driven along the roof of coal seams.For gateway height restrictions,a 1-3 m floor coal is retained,leaving a triangular floor coal at the face ends,causing a loss o...Gateways at faces of great mining heights are mostly driven along the roof of coal seams.For gateway height restrictions,a 1-3 m floor coal is retained,leaving a triangular floor coal at the face ends,causing a loss of coal.In order to improve coal recovery rates and to ensure efficiency of equipment at coal mining faces,we investigated suitable retention methods and recovery technology of floor coal at face ends.The upper floor coal can directly be recovered by a shearer with floor dinting.The lower floor coal is recovered by shearer with floor dinting after advanced floor dinting and retaining a step for protecting coal sides in a haulage gateway.Field practice shows that this method can improve the coal recovery rates at fully mechanized working faces with great mining heights.展开更多
To evaluate the thermal performance of a low-temperature electrical radiant floor heating system,an experimental facility equipped with a constant temperature chamber and different specimen floors is designed and buil...To evaluate the thermal performance of a low-temperature electrical radiant floor heating system,an experimental facility equipped with a constant temperature chamber and different specimen floors is designed and built.The heating cable is installed in the floor slab with a unit-rated power of 30 W/m.Twenty-four different schemes are worked out and tested,which include three kinds of composite floor structures and eight kinds of cable distances.The cable distances are 30,40,50,60,80,100,130,150 mm.The main affective factors of the thermal performance and their influencing regularity are discussed.The experimental results show that the system has good stability and reliability,and the ratio of the radiation heat-transfer rate to the gross heat-transfer rate is greater than 50%.When the floor structure and the cable distance are fixed,the gross heat-transfer rate of the upper floor surface has a maximum value at an optimal cable distance.Under the experimental conditions in this paper,the optimal cable distance is 50 mm.展开更多
Estimating the overall floor stability in a coal mine using deterministic methods which require complex engineering properties of floor strata is desirable,but generally it is impractical due to the difficulty of gath...Estimating the overall floor stability in a coal mine using deterministic methods which require complex engineering properties of floor strata is desirable,but generally it is impractical due to the difficulty of gathering essential input data.However,applying a quantitative methodology to describe floor quality with a single number provides a practical estimate for preliminary assessment of floor stability.The coal mine floor rating(CMFR)system,developed by the University of New South Wales(UNSW),is a rockmass classification system that provides an indicator for the competence of floor strata.The most significant components of the CMFR are uniaxial compressive strength and discontinuity intensity of floor strata.In addition to the competence of the floor,depth of cover and stress notch angle are input parameters used to assess the preliminary floor stability.In this study,CMFR methodology was applied to a Central Appalachian Coal Mine that intermittently experienced floor heave.Exploratory drill core data,overburden maps,and mine plans were utilized for the study.Additionally,qualitative data(failure/non-failure)on floor conditions of the mine entries near the core holes was collected and analyzed so that the floor quality and its relation to entry stability could be estimated by statistical methods.It was found that the current CMFR classification system is not directly applicable in assessing the floor stability of the Central Appalachian Coal Mine.In order to extend the applicability of the CMFR classification system,the methodology was modified.A calculation procedure of one of the CMFR classification system’s components,the horizontal stress rating(HSR),was changed and new parameters were added to the HSR.展开更多
基金Natural Science Foundation of China under Grant Nos.52078471,52078472 and 52208509National Key Research and Development Plan of China under Grant No.2019YFE0112700+2 种基金Natural Science Foundation of Heilongjiang Province under Grant No.LH2022E121Special Project for Basic Scientific Research Business Expenses of the Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2022C04Director’s Fund Director’s Fund of Earthquake Agency of Inner Mongolia Autonomous Region under Grant No.2023MS10。
文摘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.
文摘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.
基金supported by the Natural Science Foundation of Hunan Province(2024JJ6626)the Hunan Provincial Key Laboratory of Regional Hereditary Birth Defects Prevention and Control(HPKL202320),China.
文摘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.
文摘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.
基金2022 Annual Medical Science Research Project Plan of Hebei Province,No.20221111.
文摘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.
基金supported by the Natural Science Foundation of Henan Province(242300421246)the National Natural Science Foundation of China(52004082,U24B2041,52174073,52274079)+2 种基金the Key Research and Development Program of Henan Province(251111320400)the Program for Science&Technology Innovation Talents in Universities of Henan Province(24HASTIT021)the Program for the Scientific and Technological Innovation Team in Universities of Henan Province(23IRTSTHN005).
文摘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.
基金financially supported by the National Natural Science Foundation of China(Grant No.52008039)the Guizhou Provincial Department of Transportation Science and Technology Project(Project No.2024-121-043)the Changsha University of Science and Technology Graduate Research Innovation Project(Grant No.CLSJCX23036).
文摘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.
文摘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.
文摘BACKGROUND Pelvic floor dysfunction(PFD)is related to muscle fiber tearing during childbirth,negatively impacting postpartum quality of life of parturient.Appropriate and effective intervention is necessary to promote PFD recovery.AIM To analyze the use of hydrogen peroxide and silver ion disinfection for vaginal electrodes in conjunction with comprehensive rehabilitation therapy for postpartum women with PFD.METHODS A total of 59 women with PFD who were admitted to the hospital from May 2019 to July 2022 were divided into two groups:Control group(n=27)received comprehensive rehabilitation therapy and observation group(n=32)received intervention with pelvic floor biostimulation feedback instrument in addition to comprehensive rehabilitation therapy.The vaginal electrodes were disinfected with hydrogen peroxide and silver ion before treatment.Intervention for both groups was started 6 weeks postpartum,and rehabilitation lasted for 3 months.Pelvic floor muscle voltage,pelvic floor muscle strength,vaginal muscle voltage,vaginal muscle tone,pelvic floor function,quality of life,and incidence of postpartum PFD were compared between the two groups.RESULTS Before comprehensive rehabilitation treatment,basic data and pelvic floor function were not significantly different between the two groups.After treatment,the observation group showed significant improvements in the maximum voltage and average voltage of pelvic floor muscles,contraction time of type I and type II fibers,pelvic floor muscle strength,vaginal muscle tone,vaginal muscle voltage,and quality of life(GQOLI-74 reports),compared with the control group.The observation group had lower scores on the pelvic floor distress inventory(PFDI-20)and a lower incidence of postpartum PFD,indicating the effectiveness of the pelvic floor biostimulation feedback instrument in promoting the recovery of maternal pelvic floor function.CONCLUSION The combination of the pelvic floor biostimulation feedback instrument and comprehensive rehabilitation nursing can improve pelvic floor muscle strength,promote the recovery of vaginal muscle tone,and improve pelvic floor function and quality of life.The use of hydrogen peroxide and silver ion disinfectant demonstrated favorable antibacterial efficacy and is worthy of clinical application.
基金supported by the Key Research and Development Program of Hunan Province,China(2023SK2038).
文摘Objective:Pelvic floor sensory training is commonly used in clinical practice for the treatment of stress urinary incontinence(SUI);however,there is a lack of comparative studies evaluating pelvic floor sensation between women with SUI and healthy controls.Additionally,normative data for two-point discrimination thresholds in the female pelvic floor region remain scarce.This study aims to compare the results of 4 sensory tests in the pelvic floor region between women with mild SUI and healthy women,in order to provide reference values for two-point discrimination thresholds in this area.Methods:From April 1 to October 30,2023,108 healthy women[(32.5±3.6)years]and 90 women with mild SUI[(32.9±3.3)years]were recruited from the Third Xiangya Hospital,Central South University.Participants underwent 4 sensory tests in the pelvic floor region:Two-dot discrimination,weight perception,shape recognition,and 9-grid localization.The results were compared between the 2 groups.Results:Compared with healthy women,those with mild SUI had lower sensitivity and higher thresholds in 2-dot discrimination tests in the pelvic floor region(all P<0.001).No significant differences were found between groups in weight perception,shape recognition,or grid localization tests(P>0.05).Conclusion:Women with mild stress urinary incontinence have impaired two-point discrimination ability in the pelvic floor region.
文摘BACKGROUND Spastic pelvic floor syndrome(SPFS)is a refractory pelvic floor disease characterized by abnormal(uncoordinated)contractions of the external anal sphincter and puborectalis muscle during defecation,resulting in rectal emptation and obstructive constipation.The clinical manifestations of SPFS are mainly characterized by difficult defecation,often accompanied by a sense of anal blockage and drooping.Manual defecation is usually needed during defecation.From physical examination,it is commonly observed that the patient's anal muscle tension is high,and it is difficult or even impossible to enter with his fingers.AIM To investigate the characteristics of anorectal pressure and botulinum toxin A injection combined with biofeedback in treating pelvic floor muscle spasm syndrome.METHODS Retrospective analysis of 50 patients diagnosed with pelvic floor spasm syndrome.All patients underwent pelvic floor surface electromyography assessment,anorectal dynamics examination,botulinum toxin type A injection 100 U intramuscular injection,and two cycles of biofeedback therapy.RESULTS After the botulinum toxin A injection combined with two cycles of biofeedback therapy,the patient's postoperative resting and systolic blood pressure were significantly lower than before surgery(P<0.05).Moreover,the electromyography index of the patients in the resting stage and post-resting stages was significantly lower than before surgery(P<0.05).CONCLUSION Botulinum toxin A injection combined with biofeedback can significantly reduce pelvic floor muscle tension in treating pelvic floor muscle spasm syndrome.Anorectal manometry is an effective method to evaluate the efficacy of treatment objectively.However,randomized controlled trials are needed.
基金funded by the SWJTU Science and Technology Innovation Project(2682022CX008).
文摘The Noise,Vibration,and Harshness(NVH)experience during driving is significantly influenced by the sound insulation performance of the car floor acoustic package.As such,accurate and efficient predictions of its sound insulation performance are crucial for optimizing related noise reduction designs.However,the complex acoustic transmission mechanisms and difficulties in characterizing the sound absorption and insulation properties of the floor acoustic package pose significant challenges to traditional Computer-Aided Engineering(CAE)methods,leading to low modeling efficiency and prediction accuracy.To address these limitations,a hierarchical multiobjective decomposition system for predicting the sound insulation performance of the floor acoustic package has been developed based on an analysis of the noise transmission path.This approach involves introducing a 1D-Convolutional Neural Network(1D-CNN)model for predicting the sound insulation performance of the floor acoustic package,thereby avoiding the limitations of conventional CAE approaches that rely solely on“data-driven”methods.The proposed method was applied and tested using specific vehicle models,and the results demonstrated the effectiveness and superiority of the proposed approach relative to those obtained using 2D-CNN and Support Vector Regression(SVR)models.
基金supported by the Key Program of National Natural Science Foundation of China(No.U23A202579)the National Natural Science Foundation of China(No.42277187,42007276,41972297)the Natural Science Foundation of Hebei Province(No.D2021202002)。
文摘The presence of horizontal layered rocks in tunnel engineering significantly impacts the stability and strength of the surrounding rock mass,leading to floor heave in the tunnel.This study focused on preparing layered specimens of rock-like material with varying thickness to investigate the failure behaviors of tunnel floors.The results indicate that thin-layered rock mass exhibits weak interlayer bonding,causing rock layers near the surface to buckle and break upwards when subjected to horizontal squeezing.With an increase in the layer thickness,a transition in failure mode occurs from upward buckling to shear failure along the plane,leading to a noticeable reduction in floor heave deformation.The primary cause of significant deformation in floor heave is upward buckling failure.To address this issue,the study proposes the installation of a partition wall in the middle of the floor to mitigate heave deformation of the rock layers.The results demonstrate that the partition wall has a considerable stabilizing effect on the floor,reducing the zone of buckling failure and minimizing floor heave deformation.It is crucial for the partition wall to be sufficiently high to prevent buckling failure and ensure stability.Through simulation calculations on an engineering example,it is confirmed that implementing a partition wall can effectively reduce floor heave and enhance the stability of tunnel floor.
基金National key research and development program(2022YFC3004603)National Natural Science Foundation of China(52274098)+1 种基金National Natural Science Foundation of China-National major scientific research instrument development project(52227901)Jiangsu Province International Collaboration Program-Key national industrial technology research and development cooperation projects(BZ2023050).
文摘With the increase of mining scope,rockburst occurs frequently,but its generation mechanism has not been understood comprehensively.Based on a rockburst in the coal pillar area of high tectonic stress zones(HTSZs),this study analyzed the distribution characteristics of large-energy microseismic(MS)events by using data statistics.The mechanical cause of the MS event that induced the rockburst was revealed by means of seismic moment tensor inversion.On this basis,by using numerical simulation,this study explored the distribution characteristics of static load in rockburst area and the effect of dynamic load in the floor,and then proposed the rockburst mechanism.The results show that under the squeezing action,the floor strata in HTSZs implode and transmit energy outward in the form of stress waves.This causes the cumulative damage and stress of the coal body in the fast track of coal pillar area increase in a short time.Since the coal in this area has already been in the critical stress state,small stress changes may lead to coal failure and rockburst.In this case of rockburst,the high static load of coal is the main force source,and the dynamic load plays a role in increasing coal body damage and inducing rockburst.Combined with seismic moment tensor inversion and numerical simulation,this paper proposes a rockburst research scheme,which makes the simulation of dynamic load more reasonable.The results provide the theoretical basis for rockburst control under similar conditions.
文摘Digital twin technology, originally developed for intricate physical systems, holds great potential in women’s healthcare, particularly in the management of pelvic floor disorders. This paper delves into the development of a digital twin specifically for the female pelvic floor, which can amalgamate various data sources such as imaging, biomechanical assessments, and patient-reported outcomes to offer personalized diagnostic and therapeutic insights. Through the utilization of 3D modeling and machine learning, the digital twin may facilitate precise visualization, prediction, and individualized treatment planning. Nevertheless, it is crucial to address the ethical and practical challenges related to data privacy and ensuring fair access. As this technology progresses, it has the potential to revolutionize gynecological and obstetric care by enhancing diagnostics, customizing treatments, and increasing patient involvement.
基金supported by the project"OKTAEDR-partnership and building network."Project registration number is cz.1.07./2.4.00/31.0012.
文摘Recently the manufacture of epoxy coating and flooring materials begun to be under strong pressure to use more environmentally friendly raw materials in its composition.First tendency to reduce of solvents and diluents contained in the materials appeared at the end of 90´s.This situation was supported by the Council of Europe in 2004 to reduce VOC emissions to zero till 2020.Solvent materials were thus largely replaced by solvent free materials from which the volatile substances are not released into the air.But pressure continued to increase,and over the past decade began to take centre stage water-based epoxy.On the Czech market solvent based material is still occasionally used,but predominant are solvent free materials.There are no commonly used materials containing wastes as fillers in new water-borne and solvent-free epoxy materials.Characteristics identification of the waste material as a potential filler is a set of properties that determine the limits of secondary raw materials or waste as a filler.This paper describes the basic characteristics which must be selected to meet the requirements,to affect negatively the workability,sedimentation,properties and behavior of the final floor system.Some materials must comply with special requirements,such as resistance to chemicals,etc.Next part of paper talks about utilization of polymer floors and their mechanical properties.
文摘Machining is as old as humanity, and changes in temperature in both the machine’s internal and external environments can be of great concern as they affect the machine’s thermal stability and, thus, the machine’s dimensional accuracy. This paper is a continuation of our earlier work, which aimed to analyze the effect of the internal temperature of a machine tool as the machine is put into operation and vary the external temperature, the machine floor temperature. Some experiments are carried out under controlled conditions to study how machine tool components get heated up and how this heating up affects the machine’s accuracy due to thermally induced deviations. Additionally, another angle is added by varying the machine floor temperature. The parameters mentioned above are explored in line with the overall thermal stability of the machine tool and its dimensional accuracy. A Robodrill CNC machine tool is used. The CNC was first soaked with thermal energy by gradually raising the machine floor temperature to a certain level before putting the machine in operation. The machine was monitored, and analytical methods were deplored to evaluate thermal stability. Secondly, the machine was run idle for some time under raised floor temperature before it was put into operation. Data was also collected and analyzed. It is observed that machine thermal stability can be achieved in several ways depending on how the above parameters are joggled. This paper, in conclusion, reinforces the idea of machine tool warm-up process in conjunction with a carefully analyzed and established machine floor temperature variation for the approximation of the machine tool’s thermally stability to map the long-time behavior of the machine tool.
基金the Independent Research of the State Key Laboratory of Coal Resources and Mine Safety(No. SKLCRSM09X02)the Open Research Fund of the State Key Laboratory of Coal Resources and Mine Safety(No.08KF12)the Graduate Students of Jiangsu Province Innovation Program Funded Projects(No.CX09B_120Z) for their financial support
文摘Gateways at faces of great mining heights are mostly driven along the roof of coal seams.For gateway height restrictions,a 1-3 m floor coal is retained,leaving a triangular floor coal at the face ends,causing a loss of coal.In order to improve coal recovery rates and to ensure efficiency of equipment at coal mining faces,we investigated suitable retention methods and recovery technology of floor coal at face ends.The upper floor coal can directly be recovered by a shearer with floor dinting.The lower floor coal is recovered by shearer with floor dinting after advanced floor dinting and retaining a step for protecting coal sides in a haulage gateway.Field practice shows that this method can improve the coal recovery rates at fully mechanized working faces with great mining heights.
文摘To evaluate the thermal performance of a low-temperature electrical radiant floor heating system,an experimental facility equipped with a constant temperature chamber and different specimen floors is designed and built.The heating cable is installed in the floor slab with a unit-rated power of 30 W/m.Twenty-four different schemes are worked out and tested,which include three kinds of composite floor structures and eight kinds of cable distances.The cable distances are 30,40,50,60,80,100,130,150 mm.The main affective factors of the thermal performance and their influencing regularity are discussed.The experimental results show that the system has good stability and reliability,and the ratio of the radiation heat-transfer rate to the gross heat-transfer rate is greater than 50%.When the floor structure and the cable distance are fixed,the gross heat-transfer rate of the upper floor surface has a maximum value at an optimal cable distance.Under the experimental conditions in this paper,the optimal cable distance is 50 mm.
基金The authors would like to thank Dr.Serkan Saydam and Dr.Sungsoon Mo from the University of New South Wales for their kind support and guidance during the preparation of this manuscript.
文摘Estimating the overall floor stability in a coal mine using deterministic methods which require complex engineering properties of floor strata is desirable,but generally it is impractical due to the difficulty of gathering essential input data.However,applying a quantitative methodology to describe floor quality with a single number provides a practical estimate for preliminary assessment of floor stability.The coal mine floor rating(CMFR)system,developed by the University of New South Wales(UNSW),is a rockmass classification system that provides an indicator for the competence of floor strata.The most significant components of the CMFR are uniaxial compressive strength and discontinuity intensity of floor strata.In addition to the competence of the floor,depth of cover and stress notch angle are input parameters used to assess the preliminary floor stability.In this study,CMFR methodology was applied to a Central Appalachian Coal Mine that intermittently experienced floor heave.Exploratory drill core data,overburden maps,and mine plans were utilized for the study.Additionally,qualitative data(failure/non-failure)on floor conditions of the mine entries near the core holes was collected and analyzed so that the floor quality and its relation to entry stability could be estimated by statistical methods.It was found that the current CMFR classification system is not directly applicable in assessing the floor stability of the Central Appalachian Coal Mine.In order to extend the applicability of the CMFR classification system,the methodology was modified.A calculation procedure of one of the CMFR classification system’s components,the horizontal stress rating(HSR),was changed and new parameters were added to the HSR.
