It is important to analyze the damage evolution process of surrounding rock under different water content for the stability of engineering rock mass.Based on digital speckle correlation(DSCM),acoustic emission(AE)and ...It is important to analyze the damage evolution process of surrounding rock under different water content for the stability of engineering rock mass.Based on digital speckle correlation(DSCM),acoustic emission(AE)and electromagnetic radiation(EMR),uniaxial hierarchical cyclic loading and unloading tests were carried out on sandstones with different fracture numbers under dry,natural and saturated water content,to explore the fracture propagation,failure precursor characteristics and damage response mechanism under the influence of water content effect.The results show that with the increase of water content,the peak stress and crack initiation stress decrease gradually,and the decreases are 15.28%-21.11%and 17.64%-23.04%,respectively.The peak strain and crack initiation strain increase gradually,and the increases are 19.85%-44.53%and 19.15%-41.94%,respectively.The precracked rock with different water content is mainly characterized by tensile failure at different loading stages.However,with the increase of water content,the proportion of shear cracks gradually increases,while acoustic emission events gradually decrease,the dissipative energy and energy storage limits of the rock under peak load gradually decrease,and the charge signal increases significantly,which is because the lubrication effect of water reduces the friction coefficient between crack surfaces.展开更多
Recent advancements in additive manufacturing(AM)have revolutionized the design and production of complex engineering microstructures.Despite these advancements,their mathematical modeling and computational analysis r...Recent advancements in additive manufacturing(AM)have revolutionized the design and production of complex engineering microstructures.Despite these advancements,their mathematical modeling and computational analysis remain significant challenges.This research aims to develop an effective computational method for analyzing the free vibration of functionally graded(FG)microplates under high temperatures while resting on a Pasternak foundation(PF).This formulation leverages a new thirdorder shear deformation theory(new TSDT)for improved accuracy without requiring shear correction factors.Additionally,the modified couple stress theory(MCST)is incorporated to account for sizedependent effects in microplates.The PF is characterized by two parameters including spring stiffness(k_(w))and shear layer stiffness(k_(s)).To validate the proposed method,the results obtained are compared with those of the existing literature.Furthermore,numerical examples explore the influence of various factors on the high-temperature free vibration of FG microplates.These factors include the length scale parameter(l),geometric dimensions,material properties,and the presence of the elastic foundation.The findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal environments.In addition,the findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal environments.In addition,the results of this research will have great potential in military and defense applications such as components of submarines,fighter aircraft,and missiles.展开更多
目的运用循证医学方法对腕踝针干预术后疼痛的疗效和安全性进行系统评价和Grade评价。方法计算机检索中国知网、万方、维普、中国生物医学文献数据库、PubMed、Embase、Web of Science、Cochrane Library中关于腕踝针干预术后疼痛的随...目的运用循证医学方法对腕踝针干预术后疼痛的疗效和安全性进行系统评价和Grade评价。方法计算机检索中国知网、万方、维普、中国生物医学文献数据库、PubMed、Embase、Web of Science、Cochrane Library中关于腕踝针干预术后疼痛的随机对照试验,检索时限为建库至2023年10月。采用RevMan 5.4软件进行Meta分析。结果纳入23篇文献,共计1968例患者,Meta分析结果显示,与常规治疗相比,腕踝针能够提高术后疼痛患者的总有效率[OR=4.42,95%CI(2.60,7.50),P<0.001],术后镇痛泵药量使用减少[MD=-9.03,95%CI(-12.09,-5.98),P<0.001],术后疼痛评分降低[MD=-1.39,95%CI(-1.68,-1.09),P<0.001],可减少不良反应发生率[RR=0.40,95%CI(0.32,0.48),P<0.001]以及临床满意度[OR=3.94,95%CI(2.40,6.48),P<0.001]。Grade证据分级结果显示:总有效率、不良反应发生率和临床满意度3项结局指标为中等质量证据,VAS评分指标为低质量证据,镇痛泵药量使用指标为极低质量证据。结论腕踝针可提高总有效率,减少术后镇痛药用量,不良反应少,安全性高,为患者提供了一种安全有效的镇痛方式。展开更多
Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,...Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,we investigated the influence of composition gradient length and heterogeneous particles at the silicene/germanene(SIL/GER)heterostructure interface on heat conduction.Our results indicate that composition graded interface at the interface diminishes the thermal conductivity of the heterostructure,with a further reduction observed as the length increases,while the effect of the heterogeneous particles can be considered negligible.To unveil the influence of composition graded interface on thermal transport,we conducted phonon analysis and identified the presence of phonon localization within the interface composition graded region.Through these analyses,we have determined that the decrease in thermal conductivity is correlated with phonon localization within the heterostructure,where a stronger degree of phonon localization signifies poorer thermal conductivity in the material.Our research findings not only contribute to understanding the impact of interface gradient-induced phonon localization on thermal transport but also offer insights into the modulation of thermal conductivity in heterostructures.展开更多
Solar-powered interfacial evaporation is an energy-efficient solution for water scarcity.It requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient evaporation.Fur...Solar-powered interfacial evaporation is an energy-efficient solution for water scarcity.It requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient evaporation.Furthermore,downward salt ion transport is also desired to prevent salt accumulation.However,achieving simultaneously fast water uptake,downward salt transport,and heat localization is challenging due to highly coupled water,mass,and thermal transport.Here,we develop a structurally graded aerogel inspired by tree transport systems to collectively optimize water,salt,and thermal transport.The arched aerogel features root-like,fan-shaped microchannels for rapid water uptake and downward salt diffusion,and horizontally aligned pores near the surface for heat localization through maximizing solar absorption and minimizing conductive heat loss.These structural characteristics gave rise to consistent evaporation rates of 2.09 kg m^(-2) h^(-1) under one-sun illumination in a 3.5 wt%NaCl solution for 7 days without degradation.Even in a high-salinity solution of 20 wt%NaCl,the evaporation rates maintained stable at 1.94 kg m^(-2) h^(-1) for 8 h without salt crystal formation.This work offers a novel microstructural design to address the complex interplay of water,salt,and thermal transport.展开更多
Negatively thermo-responsive 2D membranes,which mimic the stomatal opening/closing of plants,have drawn substantial interest for tunable molecular separation processes.However,these membranes are still restricted sign...Negatively thermo-responsive 2D membranes,which mimic the stomatal opening/closing of plants,have drawn substantial interest for tunable molecular separation processes.However,these membranes are still restricted significantly on account of low water permeability and poor dynamic tunability of 2D nanochannels under temperature stimulation.Here,we present a biomimetic negatively thermo-responsive MXene membrane by covalently grafting poly(N-isopropylacrylamide)(PNIPAm)onto MXene nanosheets.The uniformly grafted PNIPAm polymer chains can enlarge the interlayer spacings for increasing water permeability while also allowing more tunability of 2D nanochannels for enhancing the capability of gradually separating multiple molecules of different sizes.As expected,the constructed membrane exhibits ultrahigh water permeance of 95.6 L m^(-2) h^(-1) bar^(-1) at 25℃,which is eight-fold higher than the state-of-the-art negatively thermoresponsive 2D membranes.Moreover,the highly temperature-tunable 2D nanochannels enable the constructed membrane to perform excellent graded molecular sieving for dye-and antibiotic-based ternary mixtures.This strategy provides new perspectives in engineering smart 2D membrane and expands the scope of temperature-responsive membranes,showing promising applications in micro/nanofluidics and molecular separation.展开更多
An analytical method for analyzing the thermal vibration of multi-directional functionally graded porous rectangular plates in fluid media with novel porosity patterns is developed in this study.Mechanical properties ...An analytical method for analyzing the thermal vibration of multi-directional functionally graded porous rectangular plates in fluid media with novel porosity patterns is developed in this study.Mechanical properties of MFG porous plates change according to the length,width,and thickness directions for various materials and the porosity distribution which can be widely applied in many fields of engineering and defence technology.Especially,new porous rules that depend on spatial coordinates and grading indexes are proposed in the present work.Applying Hamilton's principle and the refined higher-order shear deformation plate theory,the governing equation of motion of an MFG porous rectangular plate in a fluid medium(the fluid-plate system)is obtained.The fluid velocity potential is derived from the boundary conditions of the fluid-plate system and is used to compute the extra mass.The GalerkinVlasov solution is used to solve and give natural frequencies of MFG porous plates with various boundary conditions in a fluid medium.The validity and reliability of the suggested method are confirmed by comparing numerical results of the present work with those from available works in the literature.The effects of different parameters on the thermal vibration response of MFG porous rectangular plates are studied in detail.These findings demonstrate that the behavior of the structure within a liquid medium differs significantly from that within a vacuum medium.Thereby,they offer appropriate operational approaches for the structure when employed in various mediums.展开更多
基金financially supported by National Natural Science Foundation of China(No.52304136)Young Talent of Lifting Engineering for Science and Technology in Shandong,China(No.SDAST2024QTA060)Key Project of Research and Development in Liaocheng(No.2023YD02)。
文摘It is important to analyze the damage evolution process of surrounding rock under different water content for the stability of engineering rock mass.Based on digital speckle correlation(DSCM),acoustic emission(AE)and electromagnetic radiation(EMR),uniaxial hierarchical cyclic loading and unloading tests were carried out on sandstones with different fracture numbers under dry,natural and saturated water content,to explore the fracture propagation,failure precursor characteristics and damage response mechanism under the influence of water content effect.The results show that with the increase of water content,the peak stress and crack initiation stress decrease gradually,and the decreases are 15.28%-21.11%and 17.64%-23.04%,respectively.The peak strain and crack initiation strain increase gradually,and the increases are 19.85%-44.53%and 19.15%-41.94%,respectively.The precracked rock with different water content is mainly characterized by tensile failure at different loading stages.However,with the increase of water content,the proportion of shear cracks gradually increases,while acoustic emission events gradually decrease,the dissipative energy and energy storage limits of the rock under peak load gradually decrease,and the charge signal increases significantly,which is because the lubrication effect of water reduces the friction coefficient between crack surfaces.
文摘Recent advancements in additive manufacturing(AM)have revolutionized the design and production of complex engineering microstructures.Despite these advancements,their mathematical modeling and computational analysis remain significant challenges.This research aims to develop an effective computational method for analyzing the free vibration of functionally graded(FG)microplates under high temperatures while resting on a Pasternak foundation(PF).This formulation leverages a new thirdorder shear deformation theory(new TSDT)for improved accuracy without requiring shear correction factors.Additionally,the modified couple stress theory(MCST)is incorporated to account for sizedependent effects in microplates.The PF is characterized by two parameters including spring stiffness(k_(w))and shear layer stiffness(k_(s)).To validate the proposed method,the results obtained are compared with those of the existing literature.Furthermore,numerical examples explore the influence of various factors on the high-temperature free vibration of FG microplates.These factors include the length scale parameter(l),geometric dimensions,material properties,and the presence of the elastic foundation.The findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal environments.In addition,the findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal environments.In addition,the results of this research will have great potential in military and defense applications such as components of submarines,fighter aircraft,and missiles.
文摘目的运用循证医学方法对腕踝针干预术后疼痛的疗效和安全性进行系统评价和Grade评价。方法计算机检索中国知网、万方、维普、中国生物医学文献数据库、PubMed、Embase、Web of Science、Cochrane Library中关于腕踝针干预术后疼痛的随机对照试验,检索时限为建库至2023年10月。采用RevMan 5.4软件进行Meta分析。结果纳入23篇文献,共计1968例患者,Meta分析结果显示,与常规治疗相比,腕踝针能够提高术后疼痛患者的总有效率[OR=4.42,95%CI(2.60,7.50),P<0.001],术后镇痛泵药量使用减少[MD=-9.03,95%CI(-12.09,-5.98),P<0.001],术后疼痛评分降低[MD=-1.39,95%CI(-1.68,-1.09),P<0.001],可减少不良反应发生率[RR=0.40,95%CI(0.32,0.48),P<0.001]以及临床满意度[OR=3.94,95%CI(2.40,6.48),P<0.001]。Grade证据分级结果显示:总有效率、不良反应发生率和临床满意度3项结局指标为中等质量证据,VAS评分指标为低质量证据,镇痛泵药量使用指标为极低质量证据。结论腕踝针可提高总有效率,减少术后镇痛药用量,不良反应少,安全性高,为患者提供了一种安全有效的镇痛方式。
基金Project supported by the National Natural Science Foundation of China (Grant No.12104291)。
文摘Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,we investigated the influence of composition gradient length and heterogeneous particles at the silicene/germanene(SIL/GER)heterostructure interface on heat conduction.Our results indicate that composition graded interface at the interface diminishes the thermal conductivity of the heterostructure,with a further reduction observed as the length increases,while the effect of the heterogeneous particles can be considered negligible.To unveil the influence of composition graded interface on thermal transport,we conducted phonon analysis and identified the presence of phonon localization within the interface composition graded region.Through these analyses,we have determined that the decrease in thermal conductivity is correlated with phonon localization within the heterostructure,where a stronger degree of phonon localization signifies poorer thermal conductivity in the material.Our research findings not only contribute to understanding the impact of interface gradient-induced phonon localization on thermal transport but also offer insights into the modulation of thermal conductivity in heterostructures.
基金financially supported by the Research Grants Council of Hong Kong SAR(16200720)Environment and Conservation Fund of Hong Kong SAR(Project No.21/2022)+2 种基金Young Scientists Fund of National Natural Science Foundation of China(Grant No.52303106)Research Institute for Advanced Manufucturing(Project No.CD8R)the startup fund for new recruits of PolyU(Project Nos.P0038855 and P0038858)。
文摘Solar-powered interfacial evaporation is an energy-efficient solution for water scarcity.It requires solar absorbers to facilitate upward water transport and limit the heat to the surface for efficient evaporation.Furthermore,downward salt ion transport is also desired to prevent salt accumulation.However,achieving simultaneously fast water uptake,downward salt transport,and heat localization is challenging due to highly coupled water,mass,and thermal transport.Here,we develop a structurally graded aerogel inspired by tree transport systems to collectively optimize water,salt,and thermal transport.The arched aerogel features root-like,fan-shaped microchannels for rapid water uptake and downward salt diffusion,and horizontally aligned pores near the surface for heat localization through maximizing solar absorption and minimizing conductive heat loss.These structural characteristics gave rise to consistent evaporation rates of 2.09 kg m^(-2) h^(-1) under one-sun illumination in a 3.5 wt%NaCl solution for 7 days without degradation.Even in a high-salinity solution of 20 wt%NaCl,the evaporation rates maintained stable at 1.94 kg m^(-2) h^(-1) for 8 h without salt crystal formation.This work offers a novel microstructural design to address the complex interplay of water,salt,and thermal transport.
基金supported by the National Nature Science Foundation of China(No.22278179,U23A20688)the National Key Research and Development Program of China(2021YFB3802600)+3 种基金the Fundamental Research Funds for the Central Universities(JUSRP622035)National First-Class Discipline Program of Light Industry Technology and Engineering(LIFE2018-19)MOE&SAFEA for the 111 Project(B13025)Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01D030).
文摘Negatively thermo-responsive 2D membranes,which mimic the stomatal opening/closing of plants,have drawn substantial interest for tunable molecular separation processes.However,these membranes are still restricted significantly on account of low water permeability and poor dynamic tunability of 2D nanochannels under temperature stimulation.Here,we present a biomimetic negatively thermo-responsive MXene membrane by covalently grafting poly(N-isopropylacrylamide)(PNIPAm)onto MXene nanosheets.The uniformly grafted PNIPAm polymer chains can enlarge the interlayer spacings for increasing water permeability while also allowing more tunability of 2D nanochannels for enhancing the capability of gradually separating multiple molecules of different sizes.As expected,the constructed membrane exhibits ultrahigh water permeance of 95.6 L m^(-2) h^(-1) bar^(-1) at 25℃,which is eight-fold higher than the state-of-the-art negatively thermoresponsive 2D membranes.Moreover,the highly temperature-tunable 2D nanochannels enable the constructed membrane to perform excellent graded molecular sieving for dye-and antibiotic-based ternary mixtures.This strategy provides new perspectives in engineering smart 2D membrane and expands the scope of temperature-responsive membranes,showing promising applications in micro/nanofluidics and molecular separation.
文摘An analytical method for analyzing the thermal vibration of multi-directional functionally graded porous rectangular plates in fluid media with novel porosity patterns is developed in this study.Mechanical properties of MFG porous plates change according to the length,width,and thickness directions for various materials and the porosity distribution which can be widely applied in many fields of engineering and defence technology.Especially,new porous rules that depend on spatial coordinates and grading indexes are proposed in the present work.Applying Hamilton's principle and the refined higher-order shear deformation plate theory,the governing equation of motion of an MFG porous rectangular plate in a fluid medium(the fluid-plate system)is obtained.The fluid velocity potential is derived from the boundary conditions of the fluid-plate system and is used to compute the extra mass.The GalerkinVlasov solution is used to solve and give natural frequencies of MFG porous plates with various boundary conditions in a fluid medium.The validity and reliability of the suggested method are confirmed by comparing numerical results of the present work with those from available works in the literature.The effects of different parameters on the thermal vibration response of MFG porous rectangular plates are studied in detail.These findings demonstrate that the behavior of the structure within a liquid medium differs significantly from that within a vacuum medium.Thereby,they offer appropriate operational approaches for the structure when employed in various mediums.
