To meet the challenge of mismatches between power supply and demand,modern buildings must schedule flexible energy loads in order to improve the efficiency of power grids.Furthermore,it is essential to understand the ...To meet the challenge of mismatches between power supply and demand,modern buildings must schedule flexible energy loads in order to improve the efficiency of power grids.Furthermore,it is essential to understand the effectiveness of flexibility management strategies under different climate conditions and extreme weather events.Using both typical and extreme weather data from cities in five major climate zones of China,this study investigates the energy flexibility potential of an office building under three short-term HVAC management strategies in the context of different climates.The results show that the peak load flexibility and overall energy performance of the three short-term strategies were affected by the surrounding climate conditions.The peak load reduction rate of the pre-cooling and zone temperature reset strategies declined linearly as outdoor temperature increased.Under extreme climate conditions,the daily peak-load time was found to be over two hours earlier than under typical conditions,and the intensive solar radiation found in the extreme conditions can weaken the correlation between peak load reduction and outdoor temperature,risking the ability of a building’s HVAC system to maintain a comfortable indoor environment.展开更多
Five cadmium naphthalene-diphosphonates,formulated as[Cd_(1.5)(1,4-ndpaH_(2))2(4,4'-bpyH)(4,4'-bpy)0.5(H_(2)O)_(2)]2(1),[Cd(1,4-ndpaH_(2))(1,4-bib)0.5(H_(2)O)](2),[Cd(1,4-ndpaH3)2(1,2-dpe)(H_(2)O)]·(1,2-d...Five cadmium naphthalene-diphosphonates,formulated as[Cd_(1.5)(1,4-ndpaH_(2))2(4,4'-bpyH)(4,4'-bpy)0.5(H_(2)O)_(2)]2(1),[Cd(1,4-ndpaH_(2))(1,4-bib)0.5(H_(2)O)](2),[Cd(1,4-ndpaH3)2(1,2-dpe)(H_(2)O)]·(1,2-dpe)·7H_(2)O(3),(1,2-bixH)[Cd3(1,4-ndpaH)(1,4-ndpaH_(2))2(H_(2)O)_(2)](4),and[Cd(1,4-ndpaH_(2))(H_(2)O)]·H_(2)O(5),have been synthesized from the selfassembly reactions of 1,4-naphthalenediphosphonic acid(1,4-ndpaH4)with Cd(NO3)2·4H_(2)O by introducing auxiliary ligands with variation of rigidity,such as 4,4'-bipyridine(4,4'-bpy),1,4-bis(1-imidazolyl)benzene(1,4-bib),1,2-di(4-pyridyl)ethylene(1,2-dpe),1,3-di(4-pyridyl)propane(1,3-dpp),and bis(imidazol-1-ylmethyl)benzene(1,2-bix),respectively.Structure resolution by single-crystal X-ray diffraction reveals that compound 1 possesses a layered framework,in which the{Cd3(PO2)2}trimers made up of corner-sharing two{CdO4N2}and one{CdO6}octahedra are connected by phosphonate groups,forming a ribbon,which are cross-linked by 4,4'-bipy ligands,forming a 2D layer.Compound 2 shows a 3D open-framework structure,where chains of corner-sharing{CdO4N}trigonal bipyramids and{PO3C}tetrahedra are cross-linked by 1,4-bib and/or phosphonate groups.A 1D ladder-like chain structure is found in compound 3,where the ladder-like chains made up of corner-sharing{CdO5N}octahedra and{PO3C}tetra hedra are connected by 1,4-ndpaH_(2)^(2-).Both compounds 4 and 5 obtained by the introduction of flexible ligands during the synthesis show a 2D layered structure,which is formed by ligand crosslinking double metal chains.Interestingly,In 4,flexible 1,2-bix was singly protonated,as guest molecules,filled between layer and layer,while flexible ligand 1,3-dpp is absent in 5.Photophysical measurements indicate that compounds 1-5 show ligand-centered emissions.展开更多
The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this is...The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this issue by leveraging screen-printing technology to fabricate high-performance PMSCs using innovative composite ink.The ink,a synergistic blend of few-layer graphene(Gt),carbon black(CB),and NiCo_(2)O_(4),was meticulously mixed to form a conductive and robust coating that enhanced the capacitive performance of the PMSCs.The optimized ink formulation and printing process result in a micro-supercapacitor with an exceptional areal capacitance of 18.95 mF/cm^(2)and an areal energy density of 2.63μW·h/cm^(2)at a current density of 0.05 mA/cm^(2),along with an areal power density of 0.025 mW/cm^(2).The devices demonstrated impressive durability with a capacitance retention rate of 94.7%after a stringent 20000-cycle test,demonstrating their potential for long-term applications.Moreover,the PMSCs displayed excellent mechanical flexibility,with a capacitance decrease of only 3.43%after 5000 bending cycles,highlighting their suitability for flexible electronic devices.The ease of integrating these PMSCs into series and parallel configurations for customized power further underscores their practicality for integrated power supply solutions in various technologies.展开更多
Resource management must attach importance to effective resource deployment.Aiming at the research of resource deployment system,firstly,as an important factor of resource deployment system,corporate technological inn...Resource management must attach importance to effective resource deployment.Aiming at the research of resource deployment system,firstly,as an important factor of resource deployment system,corporate technological innovation social responsibility(CISR)is analyzed.Based on this,this paper constructs a system dynamics model to analyze the changes in resource deployment system affected by CISR.The simulation model is developed using Venism personal learning edition(PLE).The results show that CISR,acted as a new factor affecting the resource deployment system,has a positive effect on resource deployment system performance.Moreover,when CISR exceeds the threshold value,the resource deployment system performance increases significantly faster,reflecting that the resource deployment system becomes more efficient.The results show that the method proposed in this paper is feasible and efficient.This research provides theoretical and practical implications for resource deployment system research.展开更多
High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limit...High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limits their use,especially in high-temperature environ-ments.A high-temperature resistant flexible piezoelectric film based on graphene oxide(GO)/polyacrylonitrile(PAN)composites was prepared by electrospinning and thermal treat-ment.It was packed into a micro-device,which could work continuously at 500℃.The intro-duction of GO significantly increased the mechanical properties of the PAN nanofibers because the oxygen-containing func-tional groups(electronegative groups)on the surface of the GO initiated a nucleophilic attack on the PAN molecule during heat treatment,enabling the GO to initiate the cyclization of the PAN at lower heat-treatment temperatures.In addition,the abund-ant oxygen-containing functional groups on GO acted as pro-oxidants to hasten the oxidation of PAN during heat treatment.The effects of GO content and heat treatment temperature on the properties of the nanofiber films were investigated.A GO/PAN nanofiber piezoelectric sensor heat-treated at 300℃had a 9.10 V and 2.25μA peak output,which are respectively 101.3%and 78.6%higher than those of the untreated films.Cyclic testing over 5000 cycles at 350℃confirmed the stable out-put performance of the GO/PAN nanofiber piezoelectric sensor.Furthermore,a sensor heat-treated at 400℃had a sensitivity of 1.7 V/N,which is 83.5%higher than that of an untreated one.The results show that the prepared GO/PAN nanofiber piezo-electric sensor combines high temperature resistance,high flexibility,stability and high sensitivity,and may have broad applic-ations in high temperature environments such as the aerospace and petroleum industries.展开更多
For rechargeable aqueous zinc-ion batteries(ZIBs),the design of nanocomposites comprised of electrochemically active materials and carbon materials with novel structures has great prom-ise in addressing the issue of e...For rechargeable aqueous zinc-ion batteries(ZIBs),the design of nanocomposites comprised of electrochemically active materials and carbon materials with novel structures has great prom-ise in addressing the issue of electrical conductivity and structural stability in the electrode materials during electrochemical cycling.We report the production of a novel flexible electrode material,by anchoring MnO_(2) nanosheets on a B,N co-doped carbon nanotube ar-ray(BNCNTs)grown on carbon cloth(BNCNTs@MnO_(2)),which was fabricated by in-situ pyrolysis and hydrothermal growth.The generated BNCNTs were strongly bonded to the surface of the car-bon fibers in the carbon cloth which provides both excellent elec-tron transport and ion diffusion,and improves the stability and dur-ability of the cathode.Importantly,the BNCNTs offer more active sites for the hydrothermal growth of MnO_(2),ensuring a uniform dis-tribution.Electrochemical tests show that BNCNTs@MnO_(2) delivers a high specific capacity of 310.7 mAh g^(−1) at 0.1 A g^(−1),along with excellent rate capability and outstanding cycling stability,with a 79.7% capacity retention after 8000 cycles at 3 A g^(−1).展开更多
Electrospinning technology has emerged as a promising method for fabricating flexible lithium-ion batter-ies(FLIBs)due to its ability to create materials with desir-able properties for energy storage applications.FLIB...Electrospinning technology has emerged as a promising method for fabricating flexible lithium-ion batter-ies(FLIBs)due to its ability to create materials with desir-able properties for energy storage applications.FLIBs,which are foldable and have high energy densities,are be-coming increasingly important as power sources for wear-able devices,flexible electronics,and mobile energy applica-tions.Carbon materials,especially carbon nanofibers,are pivotal in improving the performance of FLIBs by increas-ing electrical conductivity,chemical stability,and surface area,as well as reducing costs.These materials also play a significant role in establishing conducting networks and im-proving structural integrity,which are essential for extend-ing the cycle life and enhancing the safety of the batteries.This review considers the role of electrospinning in the fabrication of critical FLIB components,with a particular emphasis on the integration of carbon materials.It explores strategies to optimize FLIB performance by fine-tuning the electrospinning para-meters,such as electric field strength,spinning rate,solution concentration,and carbonization process.Precise control over fiber properties is crucial for enhancing battery reliability and stability during folding and bending.It also highlights the latest research findings in carbon-based electrode materials,high-performance electrolytes,and separator structures,discussing the practical challenges and opportunities these materials present.It underscores the significant impact of carbon materials on the evolution of FLIBs and their potential to shape future energy storage technologies.展开更多
Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane ex...Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane explosion protection by using an experimental platform and adjusting the blockage rate and spacing of the obstacles.It aims to reduce the risk of gas explosions in urban underground spaces.The results of the study show that the flame propagation peak speed and peak overpressure are reduced with the decrease in the blocking rate of the flexible obstacle when the blocking rate of the flexible obstacle is less than or equal to the blocking rate of the rigid obstacle,with the decrease in the spacing,the better the protection effect of the methane explosion.When the blockage rate of the flexible obstacle is greater than the blockage rate of the rigid obstacle and spacing is less than the height of the flexible obstacle,rigid and flexible obstacles are connected as a whole,increasing the strength of the explosion.This study can provide a theoretical basis and scientific guidance for optimizing rigid and flexible object hybrid layouts and methane explosion protection technology in urban underground spaces.展开更多
Reusable and flexible capturing of space debris is highly required in future aerospace technologies.A tendon-actuated flexible robotic arm is therefore proposed for capturing floating targets in this paper.Firstly,an ...Reusable and flexible capturing of space debris is highly required in future aerospace technologies.A tendon-actuated flexible robotic arm is therefore proposed for capturing floating targets in this paper.Firstly,an accurate dynamic model of the flexible robotic arm is established by using the absolute nodal coordinate formulation(ANCF)in the framework of the arbitrary Lagrangian-Eulerian(ALE)description and the natural coordinate formulation(NCF).The contact and self-contact dynamics of the flexible robotic arm when bending and grasping an object are considered via a fast contact detection approach.Then,the dynamic simulations of the flexible robotic arm for capturing floating targets are carried out to study the influence of the position,size,and mass of the target object on the grasping performance.Finally,a principle prototype of the tendon-actuated flexible robotic arm is manufactured to validate the dynamic model.The corresponding grasping experiments for objects of various shapes are also conducted to illustrate the excellent performance of the flexible robotic arm.展开更多
Flexible microporous metal rubber(FMP-MR)is widely used in national defense applications,yet its mechanical behavior under high-speed impact conditions remains insufficiently explored.In this study,dynamic and static ...Flexible microporous metal rubber(FMP-MR)is widely used in national defense applications,yet its mechanical behavior under high-speed impact conditions remains insufficiently explored.In this study,dynamic and static experiments were conducted to systematically investigate the mechanical response of metal-wrapped microporous materials under impact loading that spanned 10~6 orders of magnitude.By combining a high-precision numerical model with a spatial contact point search algorithm,the spatio–temporal contact characteristics of the complex network structure in FMP-MR were systematically analyzed.Furthermore,the mapping mechanism from turn topology and mesoscopic friction behavior to macroscopic mechanical properties was comprehensively explored.The results showed that compared with quasi-static loading,FMP-MR under high-speed impact exhibited higher energy absorption efficiency due to high-strain-rate inertia effect.Therefore,the peak stress increased by 141%,and the maximum energy dissipation increased by 300%.Consequently,the theory of dynamic friction locking effect was innovatively proposed.The theory explains that the close synergistic effect of sliding friction and plastic dissipation promoted by the stable interturn-locked embedded structure is the essential reason for the excellent dynamic mechanical properties of FMP-MR under dynamic loading conditions.Briefly,based on the in-depth investigation of the mechanical response and energy dissipation mechanism of FMP-MR under impact loads,this study provides a solid theoretical basis for further expanding the application range of FMP-MR and optimizing its performance.展开更多
目的探讨Supreme喉罩和Flexible喉罩不同通气罩内压对气道漏气压的影响。方法择期全麻乳腺手术患者,根据插入喉罩种类不同分为Supreme组(35例)和Flexible组(33例)。常规静脉麻醉诱导后由同一麻醉科医师插入Supreme或Flexible喉罩,确认...目的探讨Supreme喉罩和Flexible喉罩不同通气罩内压对气道漏气压的影响。方法择期全麻乳腺手术患者,根据插入喉罩种类不同分为Supreme组(35例)和Flexible组(33例)。常规静脉麻醉诱导后由同一麻醉科医师插入Supreme或Flexible喉罩,确认位置良好,调整通气罩压力。分别记录通气罩压力为10、20、30、40、50 cm H2O(1 cm H2O=0.098 k Pa)时,两种喉罩的气道漏气压值。结果 Supreme组通气罩内压力20、30、40、50 cm H2O时,所对应的气道漏气压差异无统计学意义(P>0.05),但均显著高于10 cm H2O时气道漏气压(P<0.05);Flexible组通气罩内压力为30、40、50 cm H2O时,所对应的气道漏气压差异无统计学意义(P>0.05),但高于10、20 cm H2O时气道漏气压(P<0.05)。Supreme组患者的整体平均气道漏气压(25.40±5.52)cm H2O明显高于Flexible组的(20.67±3.06)cm H2O(P<0.05)。结论 Supreme喉罩的平均气道漏气压高于Flexible喉罩,达到最大平均气道漏气压时,Supreme喉罩所需的通气罩内压(20 cm H2O)低于Flexible喉罩(30 cm H2O)。展开更多
Planet gear systems(PGSs)are key components of transmission mechanisms.Structural and material characteristics of gearbox and shaft can affect the support stiffness and vibrations of PGSs.The ring gear flexibility sho...Planet gear systems(PGSs)are key components of transmission mechanisms.Structural and material characteristics of gearbox and shaft can affect the support stiffness and vibrations of PGSs.The ring gear flexibility should affect the vibrations of PGSs too.However,most previous work did not completely consider the effects of the ring gear flexibility on the vibrations of PGSs and flexible supports of ring and sun gears.Thus,this paper presents a flexible-rigid coupling multi-body dynamic(FMBD)model for a PGS with the flexible supports and ring gear flexibility.A finite element model of ring gear is established to formulate the ring gear flexibility.The influences of clearance and damping of planet bearings on the vibrations of PGS are considered.The effects of flexible supports and ring gear flexibility on the vibrations of PGS under different moment and speed conditions are studied.The statistical parameters and peak frequencies of PGS from the proposed FMBD and previous rigid multi-body dynamic(RMBD)models are compared.The results denote that the flexible support has a great effect on the vibrations of PGS.This paper can provide some guidance for the support structure design and vibration control for PGSs.展开更多
基金National Key R&D Program of China of the 13th Five-Year Plan(No.2018YFD1100704)。
文摘To meet the challenge of mismatches between power supply and demand,modern buildings must schedule flexible energy loads in order to improve the efficiency of power grids.Furthermore,it is essential to understand the effectiveness of flexibility management strategies under different climate conditions and extreme weather events.Using both typical and extreme weather data from cities in five major climate zones of China,this study investigates the energy flexibility potential of an office building under three short-term HVAC management strategies in the context of different climates.The results show that the peak load flexibility and overall energy performance of the three short-term strategies were affected by the surrounding climate conditions.The peak load reduction rate of the pre-cooling and zone temperature reset strategies declined linearly as outdoor temperature increased.Under extreme climate conditions,the daily peak-load time was found to be over two hours earlier than under typical conditions,and the intensive solar radiation found in the extreme conditions can weaken the correlation between peak load reduction and outdoor temperature,risking the ability of a building’s HVAC system to maintain a comfortable indoor environment.
文摘Five cadmium naphthalene-diphosphonates,formulated as[Cd_(1.5)(1,4-ndpaH_(2))2(4,4'-bpyH)(4,4'-bpy)0.5(H_(2)O)_(2)]2(1),[Cd(1,4-ndpaH_(2))(1,4-bib)0.5(H_(2)O)](2),[Cd(1,4-ndpaH3)2(1,2-dpe)(H_(2)O)]·(1,2-dpe)·7H_(2)O(3),(1,2-bixH)[Cd3(1,4-ndpaH)(1,4-ndpaH_(2))2(H_(2)O)_(2)](4),and[Cd(1,4-ndpaH_(2))(H_(2)O)]·H_(2)O(5),have been synthesized from the selfassembly reactions of 1,4-naphthalenediphosphonic acid(1,4-ndpaH4)with Cd(NO3)2·4H_(2)O by introducing auxiliary ligands with variation of rigidity,such as 4,4'-bipyridine(4,4'-bpy),1,4-bis(1-imidazolyl)benzene(1,4-bib),1,2-di(4-pyridyl)ethylene(1,2-dpe),1,3-di(4-pyridyl)propane(1,3-dpp),and bis(imidazol-1-ylmethyl)benzene(1,2-bix),respectively.Structure resolution by single-crystal X-ray diffraction reveals that compound 1 possesses a layered framework,in which the{Cd3(PO2)2}trimers made up of corner-sharing two{CdO4N2}and one{CdO6}octahedra are connected by phosphonate groups,forming a ribbon,which are cross-linked by 4,4'-bipy ligands,forming a 2D layer.Compound 2 shows a 3D open-framework structure,where chains of corner-sharing{CdO4N}trigonal bipyramids and{PO3C}tetrahedra are cross-linked by 1,4-bib and/or phosphonate groups.A 1D ladder-like chain structure is found in compound 3,where the ladder-like chains made up of corner-sharing{CdO5N}octahedra and{PO3C}tetra hedra are connected by 1,4-ndpaH_(2)^(2-).Both compounds 4 and 5 obtained by the introduction of flexible ligands during the synthesis show a 2D layered structure,which is formed by ligand crosslinking double metal chains.Interestingly,In 4,flexible 1,2-bix was singly protonated,as guest molecules,filled between layer and layer,while flexible ligand 1,3-dpp is absent in 5.Photophysical measurements indicate that compounds 1-5 show ligand-centered emissions.
基金supported by the Shanxi Province Central Guidance Fund for Local Science and Technology Development Project(YDZJSX2024D030)the National Natural Science Foundation of China(22075197,22278290)+2 种基金the Shanxi Province Key Research and Development Program Project(2021020660301013)the Shanxi Provincial Natural Science Foundation of China(202103021224079)the Research and Development Project of Key Core and Common Technology of Shanxi Province(20201102018).
文摘The advancement of planar micro-supercapacitors(PMSCs)for micro-electromechanical systems(MEMS)has been significantly hindered by the challenge of achieving high energy and power densities.This study addresses this issue by leveraging screen-printing technology to fabricate high-performance PMSCs using innovative composite ink.The ink,a synergistic blend of few-layer graphene(Gt),carbon black(CB),and NiCo_(2)O_(4),was meticulously mixed to form a conductive and robust coating that enhanced the capacitive performance of the PMSCs.The optimized ink formulation and printing process result in a micro-supercapacitor with an exceptional areal capacitance of 18.95 mF/cm^(2)and an areal energy density of 2.63μW·h/cm^(2)at a current density of 0.05 mA/cm^(2),along with an areal power density of 0.025 mW/cm^(2).The devices demonstrated impressive durability with a capacitance retention rate of 94.7%after a stringent 20000-cycle test,demonstrating their potential for long-term applications.Moreover,the PMSCs displayed excellent mechanical flexibility,with a capacitance decrease of only 3.43%after 5000 bending cycles,highlighting their suitability for flexible electronic devices.The ease of integrating these PMSCs into series and parallel configurations for customized power further underscores their practicality for integrated power supply solutions in various technologies.
基金supported by the National Natural Science Foundation of China(72072047)the Fundamental Research Funds for the Central Universities(HIT.HSS.ESD202310)+3 种基金the Research Project on Graduates’Education and Teaching Reform of HIT(23MS011)the research Project on Higher Education of Heilongjiang Higher Education Association(23GJYBC011)the Natural Science Foundation of Shandong Province(ZR2023QG010)the Shandong Philosophy and Social Science Research Project(22CSDJ03).
文摘Resource management must attach importance to effective resource deployment.Aiming at the research of resource deployment system,firstly,as an important factor of resource deployment system,corporate technological innovation social responsibility(CISR)is analyzed.Based on this,this paper constructs a system dynamics model to analyze the changes in resource deployment system affected by CISR.The simulation model is developed using Venism personal learning edition(PLE).The results show that CISR,acted as a new factor affecting the resource deployment system,has a positive effect on resource deployment system performance.Moreover,when CISR exceeds the threshold value,the resource deployment system performance increases significantly faster,reflecting that the resource deployment system becomes more efficient.The results show that the method proposed in this paper is feasible and efficient.This research provides theoretical and practical implications for resource deployment system research.
文摘High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limits their use,especially in high-temperature environ-ments.A high-temperature resistant flexible piezoelectric film based on graphene oxide(GO)/polyacrylonitrile(PAN)composites was prepared by electrospinning and thermal treat-ment.It was packed into a micro-device,which could work continuously at 500℃.The intro-duction of GO significantly increased the mechanical properties of the PAN nanofibers because the oxygen-containing func-tional groups(electronegative groups)on the surface of the GO initiated a nucleophilic attack on the PAN molecule during heat treatment,enabling the GO to initiate the cyclization of the PAN at lower heat-treatment temperatures.In addition,the abund-ant oxygen-containing functional groups on GO acted as pro-oxidants to hasten the oxidation of PAN during heat treatment.The effects of GO content and heat treatment temperature on the properties of the nanofiber films were investigated.A GO/PAN nanofiber piezoelectric sensor heat-treated at 300℃had a 9.10 V and 2.25μA peak output,which are respectively 101.3%and 78.6%higher than those of the untreated films.Cyclic testing over 5000 cycles at 350℃confirmed the stable out-put performance of the GO/PAN nanofiber piezoelectric sensor.Furthermore,a sensor heat-treated at 400℃had a sensitivity of 1.7 V/N,which is 83.5%higher than that of an untreated one.The results show that the prepared GO/PAN nanofiber piezo-electric sensor combines high temperature resistance,high flexibility,stability and high sensitivity,and may have broad applic-ations in high temperature environments such as the aerospace and petroleum industries.
基金financial support from projects funded by the National Natural Science Foundation of China(52172038,22179017)the National Key Research and Development Program of China(2022YFB4101600,2022YFB4101601)。
文摘For rechargeable aqueous zinc-ion batteries(ZIBs),the design of nanocomposites comprised of electrochemically active materials and carbon materials with novel structures has great prom-ise in addressing the issue of electrical conductivity and structural stability in the electrode materials during electrochemical cycling.We report the production of a novel flexible electrode material,by anchoring MnO_(2) nanosheets on a B,N co-doped carbon nanotube ar-ray(BNCNTs)grown on carbon cloth(BNCNTs@MnO_(2)),which was fabricated by in-situ pyrolysis and hydrothermal growth.The generated BNCNTs were strongly bonded to the surface of the car-bon fibers in the carbon cloth which provides both excellent elec-tron transport and ion diffusion,and improves the stability and dur-ability of the cathode.Importantly,the BNCNTs offer more active sites for the hydrothermal growth of MnO_(2),ensuring a uniform dis-tribution.Electrochemical tests show that BNCNTs@MnO_(2) delivers a high specific capacity of 310.7 mAh g^(−1) at 0.1 A g^(−1),along with excellent rate capability and outstanding cycling stability,with a 79.7% capacity retention after 8000 cycles at 3 A g^(−1).
文摘Electrospinning technology has emerged as a promising method for fabricating flexible lithium-ion batter-ies(FLIBs)due to its ability to create materials with desir-able properties for energy storage applications.FLIBs,which are foldable and have high energy densities,are be-coming increasingly important as power sources for wear-able devices,flexible electronics,and mobile energy applica-tions.Carbon materials,especially carbon nanofibers,are pivotal in improving the performance of FLIBs by increas-ing electrical conductivity,chemical stability,and surface area,as well as reducing costs.These materials also play a significant role in establishing conducting networks and im-proving structural integrity,which are essential for extend-ing the cycle life and enhancing the safety of the batteries.This review considers the role of electrospinning in the fabrication of critical FLIB components,with a particular emphasis on the integration of carbon materials.It explores strategies to optimize FLIB performance by fine-tuning the electrospinning para-meters,such as electric field strength,spinning rate,solution concentration,and carbonization process.Precise control over fiber properties is crucial for enhancing battery reliability and stability during folding and bending.It also highlights the latest research findings in carbon-based electrode materials,high-performance electrolytes,and separator structures,discussing the practical challenges and opportunities these materials present.It underscores the significant impact of carbon materials on the evolution of FLIBs and their potential to shape future energy storage technologies.
基金supported by the National Natural Science Foundation of China(Grant No.52274177)Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K202401501)+1 种基金Chongqing Graduate Student Research Innovation Program(Grant No.CYS240800)The Science and Technology Innovation Project for Graduate Students of Chongqing University of Science and Technology(Grant No.YKJCX2420702).
文摘Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane explosion protection by using an experimental platform and adjusting the blockage rate and spacing of the obstacles.It aims to reduce the risk of gas explosions in urban underground spaces.The results of the study show that the flame propagation peak speed and peak overpressure are reduced with the decrease in the blocking rate of the flexible obstacle when the blocking rate of the flexible obstacle is less than or equal to the blocking rate of the rigid obstacle,with the decrease in the spacing,the better the protection effect of the methane explosion.When the blockage rate of the flexible obstacle is greater than the blockage rate of the rigid obstacle and spacing is less than the height of the flexible obstacle,rigid and flexible obstacles are connected as a whole,increasing the strength of the explosion.This study can provide a theoretical basis and scientific guidance for optimizing rigid and flexible object hybrid layouts and methane explosion protection technology in urban underground spaces.
基金funded by the"14th Five-Year Plan"Civil Aerospace Pre-research Project of China(Grant No.D010301).
文摘Reusable and flexible capturing of space debris is highly required in future aerospace technologies.A tendon-actuated flexible robotic arm is therefore proposed for capturing floating targets in this paper.Firstly,an accurate dynamic model of the flexible robotic arm is established by using the absolute nodal coordinate formulation(ANCF)in the framework of the arbitrary Lagrangian-Eulerian(ALE)description and the natural coordinate formulation(NCF).The contact and self-contact dynamics of the flexible robotic arm when bending and grasping an object are considered via a fast contact detection approach.Then,the dynamic simulations of the flexible robotic arm for capturing floating targets are carried out to study the influence of the position,size,and mass of the target object on the grasping performance.Finally,a principle prototype of the tendon-actuated flexible robotic arm is manufactured to validate the dynamic model.The corresponding grasping experiments for objects of various shapes are also conducted to illustrate the excellent performance of the flexible robotic arm.
基金National Natural Science Foundation of China-NSAF(Grant No.U2330202)the National Natural Science Foundation of China(Grant Nos.52175162 and 51805086)+1 种基金Fujian Provincial Technological Innovation Key Research and Industrialization Projects(Grant Nos.2023XQ005 and 2024XQ010)The National Independent Innovation Demonstration Platform Project of Fujian Province(2024QZFX07)。
文摘Flexible microporous metal rubber(FMP-MR)is widely used in national defense applications,yet its mechanical behavior under high-speed impact conditions remains insufficiently explored.In this study,dynamic and static experiments were conducted to systematically investigate the mechanical response of metal-wrapped microporous materials under impact loading that spanned 10~6 orders of magnitude.By combining a high-precision numerical model with a spatial contact point search algorithm,the spatio–temporal contact characteristics of the complex network structure in FMP-MR were systematically analyzed.Furthermore,the mapping mechanism from turn topology and mesoscopic friction behavior to macroscopic mechanical properties was comprehensively explored.The results showed that compared with quasi-static loading,FMP-MR under high-speed impact exhibited higher energy absorption efficiency due to high-strain-rate inertia effect.Therefore,the peak stress increased by 141%,and the maximum energy dissipation increased by 300%.Consequently,the theory of dynamic friction locking effect was innovatively proposed.The theory explains that the close synergistic effect of sliding friction and plastic dissipation promoted by the stable interturn-locked embedded structure is the essential reason for the excellent dynamic mechanical properties of FMP-MR under dynamic loading conditions.Briefly,based on the in-depth investigation of the mechanical response and energy dissipation mechanism of FMP-MR under impact loads,this study provides a solid theoretical basis for further expanding the application range of FMP-MR and optimizing its performance.
文摘目的探讨Supreme喉罩和Flexible喉罩不同通气罩内压对气道漏气压的影响。方法择期全麻乳腺手术患者,根据插入喉罩种类不同分为Supreme组(35例)和Flexible组(33例)。常规静脉麻醉诱导后由同一麻醉科医师插入Supreme或Flexible喉罩,确认位置良好,调整通气罩压力。分别记录通气罩压力为10、20、30、40、50 cm H2O(1 cm H2O=0.098 k Pa)时,两种喉罩的气道漏气压值。结果 Supreme组通气罩内压力20、30、40、50 cm H2O时,所对应的气道漏气压差异无统计学意义(P>0.05),但均显著高于10 cm H2O时气道漏气压(P<0.05);Flexible组通气罩内压力为30、40、50 cm H2O时,所对应的气道漏气压差异无统计学意义(P>0.05),但高于10、20 cm H2O时气道漏气压(P<0.05)。Supreme组患者的整体平均气道漏气压(25.40±5.52)cm H2O明显高于Flexible组的(20.67±3.06)cm H2O(P<0.05)。结论 Supreme喉罩的平均气道漏气压高于Flexible喉罩,达到最大平均气道漏气压时,Supreme喉罩所需的通气罩内压(20 cm H2O)低于Flexible喉罩(30 cm H2O)。
基金Projects(51605051,51975068)supported by the National Natural Science Foundation of China。
文摘Planet gear systems(PGSs)are key components of transmission mechanisms.Structural and material characteristics of gearbox and shaft can affect the support stiffness and vibrations of PGSs.The ring gear flexibility should affect the vibrations of PGSs too.However,most previous work did not completely consider the effects of the ring gear flexibility on the vibrations of PGSs and flexible supports of ring and sun gears.Thus,this paper presents a flexible-rigid coupling multi-body dynamic(FMBD)model for a PGS with the flexible supports and ring gear flexibility.A finite element model of ring gear is established to formulate the ring gear flexibility.The influences of clearance and damping of planet bearings on the vibrations of PGS are considered.The effects of flexible supports and ring gear flexibility on the vibrations of PGS under different moment and speed conditions are studied.The statistical parameters and peak frequencies of PGS from the proposed FMBD and previous rigid multi-body dynamic(RMBD)models are compared.The results denote that the flexible support has a great effect on the vibrations of PGS.This paper can provide some guidance for the support structure design and vibration control for PGSs.
基金supported by National Natural Science Foundation of China (No.51065026)Doctoral Foundation of Ministry of Education of China (No.20106501110001)Natural Science Foundation of Autonomous Region (No.2011211A002)
