The preparation of the poly（3-hexylthiophene） （P3HT） stripe structure with oriented nanofibrils prepared by controlled inclining evaporative technique is reported. The distance of the adjacent stripes could be con...The preparation of the poly（3-hexylthiophene） （P3HT） stripe structure with oriented nanofibrils prepared by controlled inclining evaporative technique is reported. The distance of the adjacent stripes could be controlled from 40 μm to 100 μm by decreasing the inclining angle. The oriented nanofibrils in the stripes can be obtained because the P3HT lamellae diffuse directionally and form 1D crystals at the three-phase contact line of the drop. In order to get the oriented P3HT stripes, the proper solvent evaporation rate which is controlled by the inclining angle and the wettability of the substrate must be carefully chosen to match the P3HT 1D crystallization rate. It is found that large inclining angle and the hydrophilic substrate （for example： glass and PEDOT） are beneficial to get P3HT stripe structure with oriented nanofibrils.展开更多
There are wide applications of block-rate pricing schemes in many countries.However,there are no significant studies that apply this common tariff for smart home energy management systems.In this paper,a three-time-fr...There are wide applications of block-rate pricing schemes in many countries.However,there are no significant studies that apply this common tariff for smart home energy management systems.In this paper,a three-time-frame energy management scheme has been proposed for photovoltaic(PV)-powered grid-connected smart homes based on the well-known mixed-integer linear programming optimization technique.This paper provides three original and novel smart home energy management algorithms that depend on the most common residential tariff specifically in developing countries.Three different management concepts have been studied for a typical Egyptian house.The concepts of shifting load,vehicle-to-home and reducing air conditioning have been tested according to a commonly applied slab tariff.The proposed scheme considers the home battery extending lifetime constraints.It also preserves comfortable lifestyle limits for home users according to Arab housing climatic conditions and culture.Moreover,the economic feasibility of integrated PV modules for the studied home has been verified according to the Egyptian tariff.The proposed energy management scheme of PV-powered home reduces the electrical power bill significantly in a wide range from 61%to only 19%of the default case bill according to the applied management technique.展开更多
Backfill is routinely adopted as a ground support measure for underground mines.However,ground stability enhancement by backfill has received limited research attention.This is likely to be because of the conventional...Backfill is routinely adopted as a ground support measure for underground mines.However,ground stability enhancement by backfill has received limited research attention.This is likely to be because of the conventional assumption that the fill material exhibits a significantly lower stiffness than the host rocks.Significantly,a recent pioneering work revealed the time-dependent ground stability around a backfilled stope with vertical walls through numerical modeling.In practice,underground stopes typically exhibit a higher or lower degree of inclination.This alters the stress state in peripheral rocks and may induce severe instability and dilution,particularly in stope-hanging walls.Hence,it is imperative to analyze the time-dependent ground stability of inclined backfilled stopes for backfill structure design.Therefore,comprehensive numerical simulations were performed using FLAC3D to address this knowledge deficiency by incorporating a coupled analysis of the backfill consolidation behavior and long-term creep deformation in surrounding rocks.The ground stability was evaluated based on the confinement effectiveness,strength-stress ratio,stress path relative to the yield surface,and time-dependent stress redistribution in the rocks.A parametric study revealed that the inclination angle of the backfilled stope reduced the confinement effectiveness in the host rocks when the wall creep was minor.This exacerbated the rock mass sloughing potential.However,a backfilled stope with a shallower dip angle achieved superior ground stability enhancement when the creep deformation was substantial,by applying a more significant compression on the backfill and effectively mobilizing its passive support performance during consolidation.Additional simulations were conducted to analyze the effects of stope height and width,mine depth,mechanical properties of rocks,backfill compressibility,and filling gap on the time-dependent stress redistribution and stability around the inclined backfilled stope.展开更多
Fluid dynamic research on rectangular and trapezoidal fins is aimed at increasing heat transfer by means of large surfaces.The trapezoidal cavity form is compared with its thermal and flow performance,and it is reveal...Fluid dynamic research on rectangular and trapezoidal fins is aimed at increasing heat transfer by means of large surfaces.The trapezoidal cavity form is compared with its thermal and flow performance,and it is revealed that trapezoidal fins tend to be more efficient,particularly when material optimization is critical.Motivated by the increasing need for sustainable energy management,this work analyses the thermal performance of inclined trapezoidal and rectangular porous fins utilising a unique hybrid nanofluid.The effectiveness of nanoparticles in a working fluid is primarily determined by their thermophysical properties;hence,optimising these properties can significantly improve overall performance.This study considers the dispersion of Graphene Oxide(GO)and Molybdenum Disulfide in the base fluid,engine oil.Temperature profiles are analysed by altering the radiative,porosity,wet porous,and angle of inclination parameters.Surface and contour plots are constructed by using the Lobatto IIIa Collocation Method with BVP5C solver in MATLAB and Gradient Descent Optimisation to predict the combined heat transfer rate.According to the study,fluid temperature consistently decreases when the angle of inclination,wet porous parameter,porosity parameter,and radiative parameter increase,suggesting significantly improved heat dissipation.The trapezoidal fin consistently exhibits a superior heat transfer mechanism than a rectangular fin.It is found that the trapezoidal fin transmits heat at a rate that is 0.05%higher than that of the rectangular fin.Validation of the present study is done through the comparison of previous studies.This research provides useful design insights for sophisticated engineering uses,including electrical cooling devices,heat exchangers,radiators,and solar heaters.展开更多
Seabed mining operations have been found to induce significant movement and deformation in overlying rock strata,posing serious threats to mining safety.The presence of geological faults further complicates these defo...Seabed mining operations have been found to induce significant movement and deformation in overlying rock strata,posing serious threats to mining safety.The presence of geological faults further complicates these deformation patterns.This study utilized geophysical surveys and the continuum-based discrete element method(CDEM)to investigate how fault activity influences rock deformation and failure.The results demonstrate that:1)Acting in mechanically weak zones,faults exerted a pronounced barrier effect on deformation propagation and stress redistribution within the surrounding rock,leading to markedly divergent displacement patterns on either side of the fault plane.Comparative analyses between single-fault and double-fault models revealed an 18%−22%expansion of the damage zone under the latter,together with significantly intensified deformation and failure;2)The double-fault model exhibited a larger maximum cumulative vertical displacement and a spatial shift in the location of peak deformation,thereby posing a heightened threat to mine safety;3)Acting in an orebody substitute,backfill effectively constrained surrounding rock deformation,enhanced its load-bearing capacity,and delayed the overburden subsidence.Nevertheless,backfill only reduced the amplitude of deformation;it could not entirely prevent settlement.These findings provide essential theoretical insights and foundational knowledge for safer submarine mining practices.展开更多
When the expressway crosses the goafs inevitably,the design is generally to build the road on coal pillars as much as possible.However,the existing coal pillars are often unable to meet relevant requirements of highwa...When the expressway crosses the goafs inevitably,the design is generally to build the road on coal pillars as much as possible.However,the existing coal pillars are often unable to meet relevant requirements of highway construction.Combining three-dimensional physical model tests,numerical simulations and field monitoring,with the Urumqi East Second Ring Road passing through acute inclined goafs as a background,the deformation and failure mechanism of the overlying rock and coal pillars in acute inclined goafs under expressway load were studied.And in accordance with construction requirements of subgrade,comprehensive consideration of the deformation and instability mechanism of acute inclined goafs,the treatment measures and suggestions for this type of geological disasters were put forward.The research results confirmed the rationality of coal pillars in acute inclined goafs under the expressway through grouting.According to the ratio of diff erent overlying rock thickness to coal pillar height,the change trend and value of the required grouting range were summarized,which can provide reference for similar projects.展开更多
Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety a...Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.展开更多
Oil tanks are essential components of the oil industry, facilitating the safe storage and transportation of crude oil. Safely managing oil tanks is a crucial aspect of environmental protection. Oil tanks are often use...Oil tanks are essential components of the oil industry, facilitating the safe storage and transportation of crude oil. Safely managing oil tanks is a crucial aspect of environmental protection. Oil tanks are often used under extreme operational conditions, including dynamic loads, temperature variations, etc., which may result in unpredictable deformations that can cause severe damage or tank collapses. Therefore, it is essential to establish a monitoring system to prevent and predict potential deformations. Terrestrial laser scanning (TLS) has played a significant role in oil tank monitoring over the past decades. However, the full extent of TLS capabilities for oil tank monitoring has not yet been thoroughly investigated. This study aims to evaluate TLS’s abilities in detecting deformations of oil tanks under various operating conditions. The paper has two objectives: first, to examine the deformations of two vertical oil tanks over six years, and second, to investigate potential deformations of the tanks’ surfaces during filling. Each tank was scanned three times—in the years 2015, 2016, and 2021. Mathematical models and appropriate software were developed to determine the achievable accuracy of TLS monitoring. The anticipated monitoring accuracy was simulated based on the design parameters of the oil tanks. This accuracy was subsequently used to differentiate between deformations and measurement errors. The tank surface was approximated utilizing the cylinder equation for each monitoring epoch. Additionally, deformations were analyzed at different cross-sections with the appropriate circular approximations. The results indicated that both tanks exhibited no significant deformations within a range of less than 20 mm. For the empty tanks, the average radius decreased by 4 mm, without any changes in shape. The total spatial inclination of the oil tanks was calculated using cylinder equations at different monitoring epochs. In the final stage, the observed deformations were employed to simulate the strain-stress conditions of the oil tanks. Thus, this paper presents a complex technology and the results of oil tank monitoring by TLS under various operating conditions.展开更多
The adaptation of existing natural gas pipelines for hydrogen transportation has attracted increasing attention in recent years.Yet,whether hydrogen and natural gas stratify under static conditions remains a subject o...The adaptation of existing natural gas pipelines for hydrogen transportation has attracted increasing attention in recent years.Yet,whether hydrogen and natural gas stratify under static conditions remains a subject of debate,and experimental evidence is still limited.This study presents an experimental investigation of the concentration distribution of hydrogen–natural gas mixtures under static conditions.Hydrogen concentration was measured using a KTL-2000M-H hydrogen analyzer,with a measurement range of 0–30%(by volume),an accuracy of 1%full scale(FS),and a resolution of 0.01%.Experiments were conducted in a 300 cm riser,filled with uniformly mixed hydrogen–methane standard gas,under various static conditions,including different hydrogen blending ratios(5.03%,10.03%,and 19.79%),pressures(0.5 MPa,2 MPa,and 4 MPa),and inclination angles(0◦,45◦,and 90◦).Results show that,at identical pressures and an inclination angle of 90◦,the presence of hydrogen at both ends of the riser remain nearly the same,indicating that the blending ratio exerts no significant influence on stratification.Moreover,across different pressures,the composition of the mixture remains highly uniform,with the maximum difference between the top and bottom of the riser limited to approximately 0.02%,well within the instrument’s margin of error—demonstrating that pressure has a negligible effect on hydrogen stratification.Similarly,variations in inclination angle exert minimal influence on hydrogen distribution.At 4 MPa,the concentration difference between the top and bottom ranges from 0.01%to 0.02%,confirming the absence of measurable stratification within experimental accuracy.展开更多
Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady ...Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady heat and mass transport properties.The hybrid nanofluid’s enhanced heat transfer efficiency is a major benefit in high-performance engineering applications.It is composed of two separate nanoparticles suspended in a base fluid and is chosen for its improved thermal properties.Thermal radiation,chemical reactions,a transverse magnetic field,surface stretching with time,injection or suction through the porous medium,and the effect of inclination,which introduces gravity-induced buoyancy forces,are all important physical phenomena that are taken into account in the analysis.A system of nonlinear ordinary differential equations(ODEs)is derived from the governing partial differential equations for mass,momentum,and energy by applying suitable similarity transformations.This simplifies the modeling procedure.The bvp4c solver in MATLAB is then used to numerically solve these equations.Different governing parameters modify temperature,concentration,and velocity profiles in graphs and tables.These factors include radiation intensity,chemical reaction rate,magnetic field strength,unsteadiness,suction/injection velocity,inclination angle,and nanoparticle concentration.A complex relationship between buoyancy and magnetic factors makes hybrid nanofluids better at heat transmission than regular ones.Thermal systems including cooling technologies,thermal coatings,and electronic heat management benefit from these findings.展开更多
The pantograph area is a critical source of aerodynamic noise in high-speed trains,generating noise both directly and through its cavity,a factor that warrants considerable attention.One effective method for reducing ...The pantograph area is a critical source of aerodynamic noise in high-speed trains,generating noise both directly and through its cavity,a factor that warrants considerable attention.One effective method for reducing aerodynamic noise within the pantograph cavity involves the introduction of a jet at the leading edge of the cavity.This study investigates the mechanisms driving cavity aerodynamic noise under varying jet velocities,using Improved Delayed Detached Eddy Simulation(IDDES)and Ffowcs Williams-Hawkings(FW-H)equations.The numerical simulations reveal that an increase in jet velocity results in a higher elevation of the shear layer above the cavity.This elevation,in turn,diminishes the interaction area between the vortices produced by jet shedding and the trailing edge of the cavity wall.Consequently,the amplitude of pressure pulsations on the cavity surface is reduced,leading to a decrease in radiated far-field noise.Specifically,simulations conducted with a jet velocity of 111.11 m/s indicate a remarkable noise reduction of approximately 4 dB attributable to this mechanism.To further enhance noise mitigation,alterations to the inclination angles of the cavity’s front and rear walls are also explored.The findings demonstrate that,at a constant jet velocity,such modifications significantly diminish pressure pulsations at the intersection of the rear wall and cavity floor,optimizing overall noise reduction and achieving a maximum reduction of approximately 6 dB.展开更多
This study introduces the lattice spring model(LSM)to investigate the incline angle of a non-uniform three-segment towed array under steady-state conditions.A numerical model was established,and parametric analysis wa...This study introduces the lattice spring model(LSM)to investigate the incline angle of a non-uniform three-segment towed array under steady-state conditions.A numerical model was established,and parametric analysis was conducted to examine the effects of towing speed and cable density on the incline angle.The numerical simulations demonstrate that for a conventional three-segment towed array with heavy vibration-isolation cable and density exceeding that of seawater,the towing speed must exceed 4 kn to maintain the acoustic cable's average incline angle below 10°.To validate the proposed LSM,a 100-meter-long towed array with variable densities was fabricated and tested through lake trials.The experimental results align closely with simulations,confirming LSM as a reliable model for predicting towed array position and posture.The study concludes by analyzing the parallel computing capabilities of LSM and its application in Fluid-Structure Interaction(FSI)problems.The model's precision and parallel computing capabilities make LSM an efficient,reliable tool for analyzing the steady-state behavior of towed systems.展开更多
This research explores the characteristics of boiling in inclined pipes,a domain of great importance in engineering.Employing an experimental visualization technique,the boiling dynamics of deionizedwater are examined...This research explores the characteristics of boiling in inclined pipes,a domain of great importance in engineering.Employing an experimental visualization technique,the boiling dynamics of deionizedwater are examined at varying inclination angles,paying special attention to the emerging flow patterns.The findings demonstrate that the inclination angle significantly impacts flow pattern transitions within the 0°to 90°range.As the heat flux rises,bubbles form in the liquid.The liquid’s inertia extends the bubble-wall contact time,thereby delaying the onset of bulk bubble flow.Beyond a 90°inclination,however,the patterning behavior is more influenced by the fluid velocity.At low speeds,incomplete pipe filling results in a large liquid plug hindering flow,while high speeds lead to full pipe filling.In general,gravity,inertia,buoyancy forces,and capillary forces are themain influential factors in the considered problem.However,an analysis of the heat transfer coefficient and boiling curve for different inclination angles reveals that the observed variations are essentially due to corresponding changes in the flow pattern.Finally,an optimal mass flux and inclination angle,able to minimize total entropy generation and improve heat transfer efficiency,are determined by means of an entropy generation analysis.展开更多
A sealed portal could significantly alter the flame shape and smoke flow characteristics in inclined tunnel fires.In inclined tunnels,two typical sealing conditions could be defined,namely the upper portal sealed and ...A sealed portal could significantly alter the flame shape and smoke flow characteristics in inclined tunnel fires.In inclined tunnels,two typical sealing conditions could be defined,namely the upper portal sealed and the lower portal sealed.In this study,the effects of tunnel slope on flame shape,flame length,along with smoke mass flow rate and induced velocity at the tunnel portal,are numerically investigated.The results show that,in all scenarios,flames initially rise vertically but tilt toward the sealed portal during the quasi-steady stage,with the largest tilt angle observed in tunnels sealed at the lower portal.The slope significantly affects the flame tilt angle.The flame tilt angle in tunnels with the lower portal sealed varies irregularly with the slope,while it decreases as the slope increases in tunnels with the upper portal sealed.Subsequently,the smoke mass flow rate and induced velocity at the tunnel portal are analyzed in detail.Drawing on the obtained data,the flame length prediction models for impinging flames and non-impinging flames under different sealing conditions are developed,along with dimensionless models for smoke mass flow rate and induced wind velocity.These findings provide a theoretical foundation for the formulation of fire rescue strategies and emergency evacuation plans in inclined tunnels with one portal sealed.展开更多
The“upper coal and lower bauxite”resource distribution pattern is widespread in China,where mining of the overlying coal seam significantly alters the stress environment of the underlying bauxite layer.This study in...The“upper coal and lower bauxite”resource distribution pattern is widespread in China,where mining of the overlying coal seam significantly alters the stress environment of the underlying bauxite layer.This study investigates the stability of inclined bauxite pillars under the influence of stress redistribution caused by coal seam extraction.A theoretical model is developed to calculate the direction and magnitude of principal stresses in the inclined floor strata,and a pillar stability analysis model is established that considers the effect of principal stress rotation.The research employs a combination of theoretical analysis,physical modeling,numerical simulation,and field observation.Findings indicate that stress rotation is most pronounced at both ends of the coal seam goaf,with the maximum clockwise and counterclockwise rotation angles of 19°and-40°,respectively,observed in the bauxite layer.Inclined bauxite pillars are subjected to combined compressive and shear loading.Under such conditions,clockwise rotation of principal stress increases the shear-to-normal stress ratio,thereby reducing pillar stability.Pillars located beneath the coal wall are the first to fail due to stress concentration and principal stress rotation,which can trigger a cascade of instability among the adjacent pillars.The findings provide a theoretical basis and practical guidance for ensuring the safe co-mining of coal seams and bauxite resources.展开更多
The safety of the initial support during the construction of inclined shafts in tunnels traversing through high-hydraulic-pressure surrounding rocks is paramount.This study examines a high-hydraulic-pressure inclined ...The safety of the initial support during the construction of inclined shafts in tunnels traversing through high-hydraulic-pressure surrounding rocks is paramount.This study examines a high-hydraulic-pressure inclined shaft of a tunnel in Western Sichuan Province to analyze the damage characteristics of the initial support and propose a radial drainage and decompression treatment method.Field monitoring was conducted to assess the load and deformation of the initial support structure,and on-site investigations identified the distribution of cracked areas.In addition,numerical simulations were performed to evaluate the force and deformation characteristics of the initial support structure,which were then compared with field observations for validation.The variations in the lateral pressure coefficient and water pressure were evaluated.The results revealed that damage was primarily concentrated in the shoulder,spring line,and knee areas,with the bending moment at the knee increasing by up to 66.9%.The application of the radial drainage and decompression treatment method effectively reduced water pressure loads on the initial support.Post-treatment analysis indicated significant reductions in axial force and bending moment,enhancing structural stability.These findings provide valuable insights for improving the safety and durability of initial support systems in inclined shafts of high-hydraulicpressure railroad tunnels.展开更多
Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects...Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.展开更多
Coal mine underground reservoir(CMUR) technology mitigates water scarcity in China's coal-rich western regions but lacks tailored solutions for steeply inclined coal seams.This study develops a novel framework of ...Coal mine underground reservoir(CMUR) technology mitigates water scarcity in China's coal-rich western regions but lacks tailored solutions for steeply inclined coal seams.This study develops a novel framework of steeply inclined coal mine underground reservoirs(SICMUR),which is a paradigm shift from conventional CMUR that the coal seam itself serves as the reservoir floor,challenging conventional designs due to depth-dependent permeability and mechanical constraints.Triaxial mechanical-seepage tests on Xinjiang Wudong coal samples(100,200,300 m depths) revealed a 3.5 MPa triaxial strength increase per 100 m depth and a 58-fold post-peak permeability surge at 300 versus 100 m.Similar model simulations revealed mining-induced stress redistribution and significant deformation effects,particularly subsidence and water-conducting fractures during lower coal seam mining.Results indicate a minimum 40 m safety distance between reservoirs and lower coal seams.Critical construction parameters were investigated for Wudong mine SICMUR as collapse zone heights(9.9–12.31 m) and waterconducting fracture zone heights(31.96–37.40 m).This work systematically bridges SICMUR concepts to field implementation,offering a framework for water preservation in steeply inclined mining while addressing safety concerns,providing a new approach for water reservation in steeply inclined coal mining.展开更多
Ensuring the stability of the surrounding rock mass is of great importance during the construction of a large underground powerhouse.The presence of unfavorable structural planes within the rock mass,such as faults,ca...Ensuring the stability of the surrounding rock mass is of great importance during the construction of a large underground powerhouse.The presence of unfavorable structural planes within the rock mass,such as faults,can lead to substantial deformation and subsequent collapse.A series of in situ experiments and discrete element numerical simulations have been conducted to gain insight into the progressive failure behavior and deformation response of rocks in relation to controlled collapse scenarios involving gently inclined faults.First,the unloading damage evolution process of the surrounding rock mass is characterized by microscopic analysis using microseismic(MS)data.Second,the moment tensor inversion method is used to elucidate the temporal distribution of MS event fracture types in the surrounding rock mass.During the development stage of the collapse,numerous tensile fracture events occur,while a few shear fractures corresponding to structural plane dislocation precede their occurrence.The use of the digital panoramic borehole camera,acoustic wave test,and numerical simulation revealed that gently inclined faults and deep cracks at a certain depth from the cavern periphery are the primary factors contributing to rock collapse.These results provide a valuable case study that can help anticipate and mitigate fault-slip collapse incidents while providing practical insights for underground cave excavation.展开更多
Older adults are at an increased risk of developing knee osteoarthritis.High internal knee abduction moment during daily activities may elevate the risk of knee osteoarthritis.Incline walking exercise has been found t...Older adults are at an increased risk of developing knee osteoarthritis.High internal knee abduction moment during daily activities may elevate the risk of knee osteoarthritis.Incline walking exercise has been found to decrease knee abduction moment in healthy young adults.However,it is unknown if this occurs in healthy older adults.The purpose of this study was to quantify the internal knee abduction moment at different treadmill grades to determine if incline walking could reduce the knee abduction moment in healthy older adults.Twelve healthy older adult males walked on a treadmill at five incline grades(0%,5%,10%,15%,and 20%)at 1.34 m·s^(-1).The primary outcome variable was the internal knee abduction moment.A one-way repeated measures multivariate analysis of variance was performed to determine differences in the dependent variables among incline gradients.Peak knee abduction moment significantly decreased from level walking at all gradients in 10% increments(0%-10%,p<0.001;5%-15%,p<0.002;and 10%-20%,p=0.04).A reduction in knee abduction moment during incline walking could result in decreased knee joint loading on the medial knee compartment.For older adults,who are looking to exercise to improve their health,incline walking may be beneficial to promote lower body strength and cardiovascular ability without inflicting further harm to the aging knee joints.However,because the frontal plane knee joint was of primary interest in this study,further research is needed to determine the effects of incline walking on other joints and in other planes of motion.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 20921061, 20834005 and 51073151)the Ministry of Science and Technology of China (No. 2009CB930603)
文摘The preparation of the poly（3-hexylthiophene） （P3HT） stripe structure with oriented nanofibrils prepared by controlled inclining evaporative technique is reported. The distance of the adjacent stripes could be controlled from 40 μm to 100 μm by decreasing the inclining angle. The oriented nanofibrils in the stripes can be obtained because the P3HT lamellae diffuse directionally and form 1D crystals at the three-phase contact line of the drop. In order to get the oriented P3HT stripes, the proper solvent evaporation rate which is controlled by the inclining angle and the wettability of the substrate must be carefully chosen to match the P3HT 1D crystallization rate. It is found that large inclining angle and the hydrophilic substrate （for example： glass and PEDOT） are beneficial to get P3HT stripe structure with oriented nanofibrils.
基金supported by the project entitled‘Smart Homes Energy Management Strategies’,Project ID:4915,JESOR-2015-Cycle 4,which is sponsored by the Egyptian Academy of Scientific Research and Technology(ASRT),Cairo,Egypt.
文摘There are wide applications of block-rate pricing schemes in many countries.However,there are no significant studies that apply this common tariff for smart home energy management systems.In this paper,a three-time-frame energy management scheme has been proposed for photovoltaic(PV)-powered grid-connected smart homes based on the well-known mixed-integer linear programming optimization technique.This paper provides three original and novel smart home energy management algorithms that depend on the most common residential tariff specifically in developing countries.Three different management concepts have been studied for a typical Egyptian house.The concepts of shifting load,vehicle-to-home and reducing air conditioning have been tested according to a commonly applied slab tariff.The proposed scheme considers the home battery extending lifetime constraints.It also preserves comfortable lifestyle limits for home users according to Arab housing climatic conditions and culture.Moreover,the economic feasibility of integrated PV modules for the studied home has been verified according to the Egyptian tariff.The proposed energy management scheme of PV-powered home reduces the electrical power bill significantly in a wide range from 61%to only 19%of the default case bill according to the applied management technique.
基金funding support from the National Natural Science Foundation of China(Nos.52304101 and 52204153)the China Postdoctoral Science Foundation(No.2023MD734215)+2 种基金the Youth Talent Support Program of Xi’an Association for Science and Technology(No.959202413070)the Key Research and Development Program of Shaanxi(No.2023-LL-QY-07)the Key Research and Development Program of Zhejiang(No.2023C03182).
文摘Backfill is routinely adopted as a ground support measure for underground mines.However,ground stability enhancement by backfill has received limited research attention.This is likely to be because of the conventional assumption that the fill material exhibits a significantly lower stiffness than the host rocks.Significantly,a recent pioneering work revealed the time-dependent ground stability around a backfilled stope with vertical walls through numerical modeling.In practice,underground stopes typically exhibit a higher or lower degree of inclination.This alters the stress state in peripheral rocks and may induce severe instability and dilution,particularly in stope-hanging walls.Hence,it is imperative to analyze the time-dependent ground stability of inclined backfilled stopes for backfill structure design.Therefore,comprehensive numerical simulations were performed using FLAC3D to address this knowledge deficiency by incorporating a coupled analysis of the backfill consolidation behavior and long-term creep deformation in surrounding rocks.The ground stability was evaluated based on the confinement effectiveness,strength-stress ratio,stress path relative to the yield surface,and time-dependent stress redistribution in the rocks.A parametric study revealed that the inclination angle of the backfilled stope reduced the confinement effectiveness in the host rocks when the wall creep was minor.This exacerbated the rock mass sloughing potential.However,a backfilled stope with a shallower dip angle achieved superior ground stability enhancement when the creep deformation was substantial,by applying a more significant compression on the backfill and effectively mobilizing its passive support performance during consolidation.Additional simulations were conducted to analyze the effects of stope height and width,mine depth,mechanical properties of rocks,backfill compressibility,and filling gap on the time-dependent stress redistribution and stability around the inclined backfilled stope.
基金supported by the“Regional Innovation System&Education(RISE)”through the Seoul RISE Center,funded by the Ministry of Education(MOE)and the Seoul Metropolitan Government(2025-RISE-01-027-04).
文摘Fluid dynamic research on rectangular and trapezoidal fins is aimed at increasing heat transfer by means of large surfaces.The trapezoidal cavity form is compared with its thermal and flow performance,and it is revealed that trapezoidal fins tend to be more efficient,particularly when material optimization is critical.Motivated by the increasing need for sustainable energy management,this work analyses the thermal performance of inclined trapezoidal and rectangular porous fins utilising a unique hybrid nanofluid.The effectiveness of nanoparticles in a working fluid is primarily determined by their thermophysical properties;hence,optimising these properties can significantly improve overall performance.This study considers the dispersion of Graphene Oxide(GO)and Molybdenum Disulfide in the base fluid,engine oil.Temperature profiles are analysed by altering the radiative,porosity,wet porous,and angle of inclination parameters.Surface and contour plots are constructed by using the Lobatto IIIa Collocation Method with BVP5C solver in MATLAB and Gradient Descent Optimisation to predict the combined heat transfer rate.According to the study,fluid temperature consistently decreases when the angle of inclination,wet porous parameter,porosity parameter,and radiative parameter increase,suggesting significantly improved heat dissipation.The trapezoidal fin consistently exhibits a superior heat transfer mechanism than a rectangular fin.It is found that the trapezoidal fin transmits heat at a rate that is 0.05%higher than that of the rectangular fin.Validation of the present study is done through the comparison of previous studies.This research provides useful design insights for sophisticated engineering uses,including electrical cooling devices,heat exchangers,radiators,and solar heaters.
基金Project(42072305)supported by the National Natural Science Foundation of China。
文摘Seabed mining operations have been found to induce significant movement and deformation in overlying rock strata,posing serious threats to mining safety.The presence of geological faults further complicates these deformation patterns.This study utilized geophysical surveys and the continuum-based discrete element method(CDEM)to investigate how fault activity influences rock deformation and failure.The results demonstrate that:1)Acting in mechanically weak zones,faults exerted a pronounced barrier effect on deformation propagation and stress redistribution within the surrounding rock,leading to markedly divergent displacement patterns on either side of the fault plane.Comparative analyses between single-fault and double-fault models revealed an 18%−22%expansion of the damage zone under the latter,together with significantly intensified deformation and failure;2)The double-fault model exhibited a larger maximum cumulative vertical displacement and a spatial shift in the location of peak deformation,thereby posing a heightened threat to mine safety;3)Acting in an orebody substitute,backfill effectively constrained surrounding rock deformation,enhanced its load-bearing capacity,and delayed the overburden subsidence.Nevertheless,backfill only reduced the amplitude of deformation;it could not entirely prevent settlement.These findings provide essential theoretical insights and foundational knowledge for safer submarine mining practices.
基金Science and Technology Major Project of Xinjiang Uygur Autonomous Region(2020A03003-7)Fundamental Research on Natural Science Program of Shaanxi Province(2021JM-180)+2 种基金Fundamental Research Funds for the Central Universities,CHD(Project for Leading Talents)(300102211302)Tianshan Cedar Plan of Science and Technology Department of Xinjiang Uygur Autonomous Region(2017XS13)Shaanxi Province Young Talent Lifting Program(CLGC202219).
文摘When the expressway crosses the goafs inevitably,the design is generally to build the road on coal pillars as much as possible.However,the existing coal pillars are often unable to meet relevant requirements of highway construction.Combining three-dimensional physical model tests,numerical simulations and field monitoring,with the Urumqi East Second Ring Road passing through acute inclined goafs as a background,the deformation and failure mechanism of the overlying rock and coal pillars in acute inclined goafs under expressway load were studied.And in accordance with construction requirements of subgrade,comprehensive consideration of the deformation and instability mechanism of acute inclined goafs,the treatment measures and suggestions for this type of geological disasters were put forward.The research results confirmed the rationality of coal pillars in acute inclined goafs under the expressway through grouting.According to the ratio of diff erent overlying rock thickness to coal pillar height,the change trend and value of the required grouting range were summarized,which can provide reference for similar projects.
基金supported by the National Natural Science Foundation of China(Nos.U2241240,12172045 and 12221002)the Opening Fund of State Key Laboratory of Explosion Science and Technology of Beijing Institute of Technology,China(No.ZDKT23-02)。
文摘Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.
文摘Oil tanks are essential components of the oil industry, facilitating the safe storage and transportation of crude oil. Safely managing oil tanks is a crucial aspect of environmental protection. Oil tanks are often used under extreme operational conditions, including dynamic loads, temperature variations, etc., which may result in unpredictable deformations that can cause severe damage or tank collapses. Therefore, it is essential to establish a monitoring system to prevent and predict potential deformations. Terrestrial laser scanning (TLS) has played a significant role in oil tank monitoring over the past decades. However, the full extent of TLS capabilities for oil tank monitoring has not yet been thoroughly investigated. This study aims to evaluate TLS’s abilities in detecting deformations of oil tanks under various operating conditions. The paper has two objectives: first, to examine the deformations of two vertical oil tanks over six years, and second, to investigate potential deformations of the tanks’ surfaces during filling. Each tank was scanned three times—in the years 2015, 2016, and 2021. Mathematical models and appropriate software were developed to determine the achievable accuracy of TLS monitoring. The anticipated monitoring accuracy was simulated based on the design parameters of the oil tanks. This accuracy was subsequently used to differentiate between deformations and measurement errors. The tank surface was approximated utilizing the cylinder equation for each monitoring epoch. Additionally, deformations were analyzed at different cross-sections with the appropriate circular approximations. The results indicated that both tanks exhibited no significant deformations within a range of less than 20 mm. For the empty tanks, the average radius decreased by 4 mm, without any changes in shape. The total spatial inclination of the oil tanks was calculated using cylinder equations at different monitoring epochs. In the final stage, the observed deformations were employed to simulate the strain-stress conditions of the oil tanks. Thus, this paper presents a complex technology and the results of oil tank monitoring by TLS under various operating conditions.
基金supported by the“Open Bidding for Selecting the Best Candidates”Project of Fujian Province(No.2023H0054)the National Natural Science Foundation of China(No.52372311)the Research and Application of Key Technologies for Clean Energy Supply(No.2023ZZ31YJ04).
文摘The adaptation of existing natural gas pipelines for hydrogen transportation has attracted increasing attention in recent years.Yet,whether hydrogen and natural gas stratify under static conditions remains a subject of debate,and experimental evidence is still limited.This study presents an experimental investigation of the concentration distribution of hydrogen–natural gas mixtures under static conditions.Hydrogen concentration was measured using a KTL-2000M-H hydrogen analyzer,with a measurement range of 0–30%(by volume),an accuracy of 1%full scale(FS),and a resolution of 0.01%.Experiments were conducted in a 300 cm riser,filled with uniformly mixed hydrogen–methane standard gas,under various static conditions,including different hydrogen blending ratios(5.03%,10.03%,and 19.79%),pressures(0.5 MPa,2 MPa,and 4 MPa),and inclination angles(0◦,45◦,and 90◦).Results show that,at identical pressures and an inclination angle of 90◦,the presence of hydrogen at both ends of the riser remain nearly the same,indicating that the blending ratio exerts no significant influence on stratification.Moreover,across different pressures,the composition of the mixture remains highly uniform,with the maximum difference between the top and bottom of the riser limited to approximately 0.02%,well within the instrument’s margin of error—demonstrating that pressure has a negligible effect on hydrogen stratification.Similarly,variations in inclination angle exert minimal influence on hydrogen distribution.At 4 MPa,the concentration difference between the top and bottom ranges from 0.01%to 0.02%,confirming the absence of measurable stratification within experimental accuracy.
文摘Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady heat and mass transport properties.The hybrid nanofluid’s enhanced heat transfer efficiency is a major benefit in high-performance engineering applications.It is composed of two separate nanoparticles suspended in a base fluid and is chosen for its improved thermal properties.Thermal radiation,chemical reactions,a transverse magnetic field,surface stretching with time,injection or suction through the porous medium,and the effect of inclination,which introduces gravity-induced buoyancy forces,are all important physical phenomena that are taken into account in the analysis.A system of nonlinear ordinary differential equations(ODEs)is derived from the governing partial differential equations for mass,momentum,and energy by applying suitable similarity transformations.This simplifies the modeling procedure.The bvp4c solver in MATLAB is then used to numerically solve these equations.Different governing parameters modify temperature,concentration,and velocity profiles in graphs and tables.These factors include radiation intensity,chemical reaction rate,magnetic field strength,unsteadiness,suction/injection velocity,inclination angle,and nanoparticle concentration.A complex relationship between buoyancy and magnetic factors makes hybrid nanofluids better at heat transmission than regular ones.Thermal systems including cooling technologies,thermal coatings,and electronic heat management benefit from these findings.
基金supported by National Natural Science Foundation of China(12172308).
文摘The pantograph area is a critical source of aerodynamic noise in high-speed trains,generating noise both directly and through its cavity,a factor that warrants considerable attention.One effective method for reducing aerodynamic noise within the pantograph cavity involves the introduction of a jet at the leading edge of the cavity.This study investigates the mechanisms driving cavity aerodynamic noise under varying jet velocities,using Improved Delayed Detached Eddy Simulation(IDDES)and Ffowcs Williams-Hawkings(FW-H)equations.The numerical simulations reveal that an increase in jet velocity results in a higher elevation of the shear layer above the cavity.This elevation,in turn,diminishes the interaction area between the vortices produced by jet shedding and the trailing edge of the cavity wall.Consequently,the amplitude of pressure pulsations on the cavity surface is reduced,leading to a decrease in radiated far-field noise.Specifically,simulations conducted with a jet velocity of 111.11 m/s indicate a remarkable noise reduction of approximately 4 dB attributable to this mechanism.To further enhance noise mitigation,alterations to the inclination angles of the cavity’s front and rear walls are also explored.The findings demonstrate that,at a constant jet velocity,such modifications significantly diminish pressure pulsations at the intersection of the rear wall and cavity floor,optimizing overall noise reduction and achieving a maximum reduction of approximately 6 dB.
基金supported by the Key Research Project of Zhejiang Lab(Grant No.K2022MEOAC01)。
文摘This study introduces the lattice spring model(LSM)to investigate the incline angle of a non-uniform three-segment towed array under steady-state conditions.A numerical model was established,and parametric analysis was conducted to examine the effects of towing speed and cable density on the incline angle.The numerical simulations demonstrate that for a conventional three-segment towed array with heavy vibration-isolation cable and density exceeding that of seawater,the towing speed must exceed 4 kn to maintain the acoustic cable's average incline angle below 10°.To validate the proposed LSM,a 100-meter-long towed array with variable densities was fabricated and tested through lake trials.The experimental results align closely with simulations,confirming LSM as a reliable model for predicting towed array position and posture.The study concludes by analyzing the parallel computing capabilities of LSM and its application in Fluid-Structure Interaction(FSI)problems.The model's precision and parallel computing capabilities make LSM an efficient,reliable tool for analyzing the steady-state behavior of towed systems.
基金supported by the National Natural Science Foundation of China(Project No.52166004)the National Key Research and Development Program of China(Project No.2022YFC3902000)the Major Science and Technology Special Project of Yunnan Province(Project Nos.202202AG050007,202202AG050002).
文摘This research explores the characteristics of boiling in inclined pipes,a domain of great importance in engineering.Employing an experimental visualization technique,the boiling dynamics of deionizedwater are examined at varying inclination angles,paying special attention to the emerging flow patterns.The findings demonstrate that the inclination angle significantly impacts flow pattern transitions within the 0°to 90°range.As the heat flux rises,bubbles form in the liquid.The liquid’s inertia extends the bubble-wall contact time,thereby delaying the onset of bulk bubble flow.Beyond a 90°inclination,however,the patterning behavior is more influenced by the fluid velocity.At low speeds,incomplete pipe filling results in a large liquid plug hindering flow,while high speeds lead to full pipe filling.In general,gravity,inertia,buoyancy forces,and capillary forces are themain influential factors in the considered problem.However,an analysis of the heat transfer coefficient and boiling curve for different inclination angles reveals that the observed variations are essentially due to corresponding changes in the flow pattern.Finally,an optimal mass flux and inclination angle,able to minimize total entropy generation and improve heat transfer efficiency,are determined by means of an entropy generation analysis.
基金financially supported by National Natural Science Foundation of China(NSFC)under Grant No.52208115Science and Technology Support Plan for Youth Innovation of Colleges and Universities of Shandong Province of Chain(No.2023KJ122)+2 种基金Leading Researcher Studio Fund of Jinan(No.202333050)Natural Science Foundation of Shandong Province(ZR2024ME027)Young Talent of Lifting engineering for Science and Technology in Shandong,China(SDAST2024QTA077).
文摘A sealed portal could significantly alter the flame shape and smoke flow characteristics in inclined tunnel fires.In inclined tunnels,two typical sealing conditions could be defined,namely the upper portal sealed and the lower portal sealed.In this study,the effects of tunnel slope on flame shape,flame length,along with smoke mass flow rate and induced velocity at the tunnel portal,are numerically investigated.The results show that,in all scenarios,flames initially rise vertically but tilt toward the sealed portal during the quasi-steady stage,with the largest tilt angle observed in tunnels sealed at the lower portal.The slope significantly affects the flame tilt angle.The flame tilt angle in tunnels with the lower portal sealed varies irregularly with the slope,while it decreases as the slope increases in tunnels with the upper portal sealed.Subsequently,the smoke mass flow rate and induced velocity at the tunnel portal are analyzed in detail.Drawing on the obtained data,the flame length prediction models for impinging flames and non-impinging flames under different sealing conditions are developed,along with dimensionless models for smoke mass flow rate and induced wind velocity.These findings provide a theoretical foundation for the formulation of fire rescue strategies and emergency evacuation plans in inclined tunnels with one portal sealed.
基金Project(2021YFC2902101)supported by the National Key Research and Development Program of ChinaProjects(42271139,52174135)supported by the National Natural Science Foundation of China。
文摘The“upper coal and lower bauxite”resource distribution pattern is widespread in China,where mining of the overlying coal seam significantly alters the stress environment of the underlying bauxite layer.This study investigates the stability of inclined bauxite pillars under the influence of stress redistribution caused by coal seam extraction.A theoretical model is developed to calculate the direction and magnitude of principal stresses in the inclined floor strata,and a pillar stability analysis model is established that considers the effect of principal stress rotation.The research employs a combination of theoretical analysis,physical modeling,numerical simulation,and field observation.Findings indicate that stress rotation is most pronounced at both ends of the coal seam goaf,with the maximum clockwise and counterclockwise rotation angles of 19°and-40°,respectively,observed in the bauxite layer.Inclined bauxite pillars are subjected to combined compressive and shear loading.Under such conditions,clockwise rotation of principal stress increases the shear-to-normal stress ratio,thereby reducing pillar stability.Pillars located beneath the coal wall are the first to fail due to stress concentration and principal stress rotation,which can trigger a cascade of instability among the adjacent pillars.The findings provide a theoretical basis and practical guidance for ensuring the safe co-mining of coal seams and bauxite resources.
基金supported by the National Natural Science Foundation of China(Grant Nos.42277165,41920104007)the Hubei Natural Science Foundation(Grant No.2023AFD217).
文摘The safety of the initial support during the construction of inclined shafts in tunnels traversing through high-hydraulic-pressure surrounding rocks is paramount.This study examines a high-hydraulic-pressure inclined shaft of a tunnel in Western Sichuan Province to analyze the damage characteristics of the initial support and propose a radial drainage and decompression treatment method.Field monitoring was conducted to assess the load and deformation of the initial support structure,and on-site investigations identified the distribution of cracked areas.In addition,numerical simulations were performed to evaluate the force and deformation characteristics of the initial support structure,which were then compared with field observations for validation.The variations in the lateral pressure coefficient and water pressure were evaluated.The results revealed that damage was primarily concentrated in the shoulder,spring line,and knee areas,with the bending moment at the knee increasing by up to 66.9%.The application of the radial drainage and decompression treatment method effectively reduced water pressure loads on the initial support.Post-treatment analysis indicated significant reductions in axial force and bending moment,enhancing structural stability.These findings provide valuable insights for improving the safety and durability of initial support systems in inclined shafts of high-hydraulicpressure railroad tunnels.
基金Projects(52278395,52208409) supported by the National Natural Science Foundation of ChinaProject(2022JJ40531) supported by the Natural Science Foundation of Hunan Province,China。
文摘Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.
基金supported by Beijing Natural Science Foundation (No.8254049)the National Natural Science Foundation of China (No.52374139)the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project (No.2024ZD1004505)。
文摘Coal mine underground reservoir(CMUR) technology mitigates water scarcity in China's coal-rich western regions but lacks tailored solutions for steeply inclined coal seams.This study develops a novel framework of steeply inclined coal mine underground reservoirs(SICMUR),which is a paradigm shift from conventional CMUR that the coal seam itself serves as the reservoir floor,challenging conventional designs due to depth-dependent permeability and mechanical constraints.Triaxial mechanical-seepage tests on Xinjiang Wudong coal samples(100,200,300 m depths) revealed a 3.5 MPa triaxial strength increase per 100 m depth and a 58-fold post-peak permeability surge at 300 versus 100 m.Similar model simulations revealed mining-induced stress redistribution and significant deformation effects,particularly subsidence and water-conducting fractures during lower coal seam mining.Results indicate a minimum 40 m safety distance between reservoirs and lower coal seams.Critical construction parameters were investigated for Wudong mine SICMUR as collapse zone heights(9.9–12.31 m) and waterconducting fracture zone heights(31.96–37.40 m).This work systematically bridges SICMUR concepts to field implementation,offering a framework for water preservation in steeply inclined mining while addressing safety concerns,providing a new approach for water reservation in steeply inclined coal mining.
基金funding support from the National Natural Science Foundation of China(Grant Nos.U23A2060,42177143,and 42277461).
文摘Ensuring the stability of the surrounding rock mass is of great importance during the construction of a large underground powerhouse.The presence of unfavorable structural planes within the rock mass,such as faults,can lead to substantial deformation and subsequent collapse.A series of in situ experiments and discrete element numerical simulations have been conducted to gain insight into the progressive failure behavior and deformation response of rocks in relation to controlled collapse scenarios involving gently inclined faults.First,the unloading damage evolution process of the surrounding rock mass is characterized by microscopic analysis using microseismic(MS)data.Second,the moment tensor inversion method is used to elucidate the temporal distribution of MS event fracture types in the surrounding rock mass.During the development stage of the collapse,numerous tensile fracture events occur,while a few shear fractures corresponding to structural plane dislocation precede their occurrence.The use of the digital panoramic borehole camera,acoustic wave test,and numerical simulation revealed that gently inclined faults and deep cracks at a certain depth from the cavern periphery are the primary factors contributing to rock collapse.These results provide a valuable case study that can help anticipate and mitigate fault-slip collapse incidents while providing practical insights for underground cave excavation.
基金funded,in part,by a Ball State University ASPiRE grant.
文摘Older adults are at an increased risk of developing knee osteoarthritis.High internal knee abduction moment during daily activities may elevate the risk of knee osteoarthritis.Incline walking exercise has been found to decrease knee abduction moment in healthy young adults.However,it is unknown if this occurs in healthy older adults.The purpose of this study was to quantify the internal knee abduction moment at different treadmill grades to determine if incline walking could reduce the knee abduction moment in healthy older adults.Twelve healthy older adult males walked on a treadmill at five incline grades(0%,5%,10%,15%,and 20%)at 1.34 m·s^(-1).The primary outcome variable was the internal knee abduction moment.A one-way repeated measures multivariate analysis of variance was performed to determine differences in the dependent variables among incline gradients.Peak knee abduction moment significantly decreased from level walking at all gradients in 10% increments(0%-10%,p<0.001;5%-15%,p<0.002;and 10%-20%,p=0.04).A reduction in knee abduction moment during incline walking could result in decreased knee joint loading on the medial knee compartment.For older adults,who are looking to exercise to improve their health,incline walking may be beneficial to promote lower body strength and cardiovascular ability without inflicting further harm to the aging knee joints.However,because the frontal plane knee joint was of primary interest in this study,further research is needed to determine the effects of incline walking on other joints and in other planes of motion.
