As carrier aircraft sortie frequency and flight deck operational density increase,autonomous dispatch trajectory planning for carrier-based vehicles demands efficient,safe,and kinematically feasible solutions.This pap...As carrier aircraft sortie frequency and flight deck operational density increase,autonomous dispatch trajectory planning for carrier-based vehicles demands efficient,safe,and kinematically feasible solutions.This paper presents an Iterative Safe Dispatch Corridor(iSDC)framework,addressing the suboptimality of the traditional SDC method caused by static corridor construction and redundant obstacle exploration.First,a Kinodynamic-Informed-Bidirectional Rapidly-exploring Random Tree Star(KIBRRT^(*))algorithm is proposed for the front-end coarse planning.By integrating bidirectional tree expansion,goal-biased elliptical sampling,and artificial potential field guidance,it reduces unnecessary exploration near concave obstacles and generates kinematically admissible paths.Secondly,the traditional SDC is implemented in an iterative manner,and the obtained trajectory in the current iteration is fed into the next iteration for corridor generation,thus progressively improving the quality of withincorridor constraints.For tractors,a reverse-motion penalty function is incorporated into the back-end optimizer to prioritize forward driving,aligning with mechanical constraints and human operational preferences.Numerical validations on the data of Gerald R.Ford-class carrier demonstrate that the KIBRRT^(*)reduces average computational time by 75%and expansion nodes by 25%compared to conventional RRT^(*)algorithms.Meanwhile,the iSDC framework yields more time-efficient trajectories for both carrier aircraft and tractors,with the dispatch time reduced by 31.3%and tractor reverse motion proportion decreased by 23.4%relative to traditional SDC.The presented framework offers a scalable solution for autonomous dispatch in confined and safety-critical environment,and an illustrative animation is available at bilibili.com/video/BV1tZ7Zz6Eyz.Moreover,the framework can be easily extended to three-dimension scenarios,and thus applicable for trajectory planning of aerial and underwater vehicles.展开更多
The stress wave profile at the frictional interface is crucial for investigating the frictional process.This study modeled a brittle material interface with a micro-contact to analyze the fine stress wave structure as...The stress wave profile at the frictional interface is crucial for investigating the frictional process.This study modeled a brittle material interface with a micro-contact to analyze the fine stress wave structure associated with frictional slip.Employing the finite element simulation alongside the related wave theory and experiments,two new wave structures were indentified:A Mach cone symmetric to the frictional interface associated with incident plane wave propagation,and a new plane longitudinal wave generated across the entire frictional interface at the moment when the incident wave began to propagate.The time and space of its appearance implies that the overall response of the frictional interface precedes the local wave response of the medium.Consequently,a model involving characteristic line theory and the idea of Green’s function has been proposed for its occurrence.The analysis results show that these two new wave phenomena are independent of the fracture of micro-contacts at the interface;instead,the frictional interface effect may be responsible for the generation of such new wave structures.The measured wave profiles provide a proof for the existence of the new wave structures.These results display new wave phenomena,and suggest a wave profile for investigating the dynamic mechanical properties of the frictional interface.展开更多
Polymeric carbon nitride(PCN)is identified as a promising photocatalyst for H_(2)O_(2) production due to its visible-light response,low cost,and high selectivity of 2e^(-) oxygen reduction reaction(ORR).However,the H_...Polymeric carbon nitride(PCN)is identified as a promising photocatalyst for H_(2)O_(2) production due to its visible-light response,low cost,and high selectivity of 2e^(-) oxygen reduction reaction(ORR).However,the H_(2)O_(2) yield of carbon nitride is still restricted by narrow light absorption,low charge separation efficiency,and insufficient active sites.Herein,crystalline poly(heptazine imide)(PHI)-based carbon nitride with highly dispersed In sites and N defects was prepared through the ionothermal method using LiCl/KCl as molten salts.The largeπ-conjugated system and the existence of N defects greatly enhance the visible-light harvesting ability.The remaining K^(+) ions in the nitrogen cavities of PHI serve as interlayer electron channels,and the incorporation of N defects triggers asymmetric distribution of charges on the heptazine network,promoting interlayer and in-plane charge separation and transfer,respectively.The In sites accelerate charge transfer dynamics and act as active sites for ORR.The synergistic effect of metal modification and defect engineering boosts the electron delocalization within the photocatalyst and thus significantly improves the photocatalytic activity.The H_(2)O_(2) production rate of 10InPHI reaches 15.3 mmol g^(-1)h^(-1)through a two-step single-electron ORR pathway,underscoring the great potential of modified carbon nitride materials in efficient H_(2)O_(2) photosynthesis.展开更多
4f chemistry studies the chemical bonding characteristics of fifteen lanthanide (Ln) elements in the periodic table and their wide applications in materials sciences and engineering, which forms the scientific fundame...4f chemistry studies the chemical bonding characteristics of fifteen lanthanide (Ln) elements in the periodic table and their wide applications in materials sciences and engineering, which forms the scientific fundamentals ofⅥperiodic elements in the periodic table of elements. Orbital hybridization modes of Ln elements clarify their chemical bonding nature in all reaction systems. Wide coordination number (CN) option, ranging from 2 to 16, is the reason why Ln elements are the treasure of new materials, therefore, searching for novel materials may be well carried out via the rational design of coordination environment of central Ln cations to stabilize their variable energy states. Balance utilization of Ln elements is dependent on their coordination architecture in the crystallographic frame, Ln elements can be replaced by non-Ln elements when CN <10, and when CN≥10 expensive Ln elements can be replaced by those cheaper ones.展开更多
Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored ...Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored in porous nanomaterials is still challenging.Here,through the template-free S-assisted pyrolysis of low-cost Fe-salts with melamine(MA),porous alveolate Fe/g-C3N4 catalysts with high-density(Fe loading up to 17.7 wt%)and increased USCAD Fe sites were synthesized.The presence of a certain amount of S species in the Fe-salts/MA system plays an important role in the formation of USCAD S-Fe-salt/CN catalysts;the S species act as a"sacrificial carrier"to increase the dispersion of Fe species through Fe-S coordination and generate porous alveolate structure by escaping in the form of SO2 during pyrolysis.The S-Fe-salt/CN catalysts exhibit greatly promoted activity and reusability for degrading various organic pollutants in advanced oxidation processes compared to the corresponding Fe-salt/CN catalysts,due to the promoted accessibility of USCAD Fe sites by the porous alveolate structure.This S-assisted method exhibits good feasibility in a large variety of S species(thiourea,S powder,and NH4SCN)and Fe salts,providing a new avenue for the low-cost and large-scale synthesis of high-density USCAD metal/g-C3N4 catalysts.展开更多
In this paper,the degradation of mechanical properties of engineering cementitious composites(ECCs)at elevated temperatures and the failure of fiber are considered.A failure model under coupled thermo-mechanical loads...In this paper,the degradation of mechanical properties of engineering cementitious composites(ECCs)at elevated temperatures and the failure of fiber are considered.A failure model under coupled thermo-mechanical loads for ECC is developed based on bond-based peridynamics.A semi-discrete model is constructed to describe fiber–matrix interactions and simulate thermal failure in ECC.The peridynamic differential operator(PDDO)is utilized for non-local modeling of thermal fluid flow and heat transfer.A multi-rate explicit time integration method is adopted to address thermo-mechanical coupling over different time scales.Model validation is achieved through simulating transient heat transfer in a homogeneous plate,with results aligning with analytical solutions.The damage behavior of a heated ECC plate in a borehole and under a fire scenario is analyzed,providing insights for enhancing fire resistance and high-temperature performance of ECC materials and structures.展开更多
Partial isomorphic substitution of iron in an Fe(BDC)(DMF,F)metal organic framework by manganese,cobalt,and nickel has been described for the first time.Specifically,different amounts of Mn,Co and Ni have been incorpo...Partial isomorphic substitution of iron in an Fe(BDC)(DMF,F)metal organic framework by manganese,cobalt,and nickel has been described for the first time.Specifically,different amounts of Mn,Co and Ni have been incorporated into the Fe-based framework during a solvothermal crystallization procedure.Several characterization techniques,including XRD,FT-IR,SEM,EDS,TG,XPS and ICP-AES,strongly support the effective incorporation of Mn,Ni and Co into material frameworks.The catalytic performance of these materials was examined in liquid-phase degradation of phenol at 35℃and near neutral pH of 6.2.The results show that the degradation efficiency can be evidently improved by the incorporation of Mn,while it can be inhibited by the incorporation of Ni.The incorporation of Co shows no remarkable influence on the degradation process.Moreover,the ratios of n(Fe)/n(Mn)in the bimetallic MOFs have a strong impact on the degradation process.The stability and reusability of these catalysts under mild conditions were also demonstrated in this study.This work illustrates the potential of bimetallic MOF structures in developing active heterogeneous catalysts for the degradation process of toxic compounds.展开更多
Titanium in different amounts has been successfully doped into the zirconium-based metal–organic framework UiO-66 via an in situ synthesis method,resulting in a series of hybrid UiO-66-nTi MOFs.These materials mainta...Titanium in different amounts has been successfully doped into the zirconium-based metal–organic framework UiO-66 via an in situ synthesis method,resulting in a series of hybrid UiO-66-nTi MOFs.These materials maintain a relatively high crystallinity and excellent structural stability.The addition of titanium has a significant effect on the crystal size and morphology of UiO-66.The UiO-66-nTi MOFs exhibit a sphere-like crystal morphology with a smaller crystal size and a rougher surface compared to the octahedral UiO-66 crystals.展开更多
基金support of the National Key Research and Development Plan(Grant No.2021YFB3302501)the financial support of the National Science Foundation of China(Grant No.12161076)the financial support of the Fundamental Research Funds for the Central Universities(Grant No.DUT24LAB129).
文摘As carrier aircraft sortie frequency and flight deck operational density increase,autonomous dispatch trajectory planning for carrier-based vehicles demands efficient,safe,and kinematically feasible solutions.This paper presents an Iterative Safe Dispatch Corridor(iSDC)framework,addressing the suboptimality of the traditional SDC method caused by static corridor construction and redundant obstacle exploration.First,a Kinodynamic-Informed-Bidirectional Rapidly-exploring Random Tree Star(KIBRRT^(*))algorithm is proposed for the front-end coarse planning.By integrating bidirectional tree expansion,goal-biased elliptical sampling,and artificial potential field guidance,it reduces unnecessary exploration near concave obstacles and generates kinematically admissible paths.Secondly,the traditional SDC is implemented in an iterative manner,and the obtained trajectory in the current iteration is fed into the next iteration for corridor generation,thus progressively improving the quality of withincorridor constraints.For tractors,a reverse-motion penalty function is incorporated into the back-end optimizer to prioritize forward driving,aligning with mechanical constraints and human operational preferences.Numerical validations on the data of Gerald R.Ford-class carrier demonstrate that the KIBRRT^(*)reduces average computational time by 75%and expansion nodes by 25%compared to conventional RRT^(*)algorithms.Meanwhile,the iSDC framework yields more time-efficient trajectories for both carrier aircraft and tractors,with the dispatch time reduced by 31.3%and tractor reverse motion proportion decreased by 23.4%relative to traditional SDC.The presented framework offers a scalable solution for autonomous dispatch in confined and safety-critical environment,and an illustrative animation is available at bilibili.com/video/BV1tZ7Zz6Eyz.Moreover,the framework can be easily extended to three-dimension scenarios,and thus applicable for trajectory planning of aerial and underwater vehicles.
基金supported by the National Natural Science Foundation of China(Grant No.12272127)the Construction Project of Double First Class in Safety Discipline of the Universities of Henan Province(Grant No.AQ20230751).
文摘The stress wave profile at the frictional interface is crucial for investigating the frictional process.This study modeled a brittle material interface with a micro-contact to analyze the fine stress wave structure associated with frictional slip.Employing the finite element simulation alongside the related wave theory and experiments,two new wave structures were indentified:A Mach cone symmetric to the frictional interface associated with incident plane wave propagation,and a new plane longitudinal wave generated across the entire frictional interface at the moment when the incident wave began to propagate.The time and space of its appearance implies that the overall response of the frictional interface precedes the local wave response of the medium.Consequently,a model involving characteristic line theory and the idea of Green’s function has been proposed for its occurrence.The analysis results show that these two new wave phenomena are independent of the fracture of micro-contacts at the interface;instead,the frictional interface effect may be responsible for the generation of such new wave structures.The measured wave profiles provide a proof for the existence of the new wave structures.These results display new wave phenomena,and suggest a wave profile for investigating the dynamic mechanical properties of the frictional interface.
基金supported by the National Natural Science Foundation of China (22278056, 22478058)the Fundamental Research Funds for the Central Universities (DUT22LAB602)the National Key Research and Development Program of China (2022YFA1504402)。
文摘Polymeric carbon nitride(PCN)is identified as a promising photocatalyst for H_(2)O_(2) production due to its visible-light response,low cost,and high selectivity of 2e^(-) oxygen reduction reaction(ORR).However,the H_(2)O_(2) yield of carbon nitride is still restricted by narrow light absorption,low charge separation efficiency,and insufficient active sites.Herein,crystalline poly(heptazine imide)(PHI)-based carbon nitride with highly dispersed In sites and N defects was prepared through the ionothermal method using LiCl/KCl as molten salts.The largeπ-conjugated system and the existence of N defects greatly enhance the visible-light harvesting ability.The remaining K^(+) ions in the nitrogen cavities of PHI serve as interlayer electron channels,and the incorporation of N defects triggers asymmetric distribution of charges on the heptazine network,promoting interlayer and in-plane charge separation and transfer,respectively.The In sites accelerate charge transfer dynamics and act as active sites for ORR.The synergistic effect of metal modification and defect engineering boosts the electron delocalization within the photocatalyst and thus significantly improves the photocatalytic activity.The H_(2)O_(2) production rate of 10InPHI reaches 15.3 mmol g^(-1)h^(-1)through a two-step single-electron ORR pathway,underscoring the great potential of modified carbon nitride materials in efficient H_(2)O_(2) photosynthesis.
基金supported by the National Key Research and Development Program of China(2016YFB0701004)Jilin Province Science and Technology Development Project(20170101092JC)
文摘4f chemistry studies the chemical bonding characteristics of fifteen lanthanide (Ln) elements in the periodic table and their wide applications in materials sciences and engineering, which forms the scientific fundamentals ofⅥperiodic elements in the periodic table of elements. Orbital hybridization modes of Ln elements clarify their chemical bonding nature in all reaction systems. Wide coordination number (CN) option, ranging from 2 to 16, is the reason why Ln elements are the treasure of new materials, therefore, searching for novel materials may be well carried out via the rational design of coordination environment of central Ln cations to stabilize their variable energy states. Balance utilization of Ln elements is dependent on their coordination architecture in the crystallographic frame, Ln elements can be replaced by non-Ln elements when CN <10, and when CN≥10 expensive Ln elements can be replaced by those cheaper ones.
文摘Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored in porous nanomaterials is still challenging.Here,through the template-free S-assisted pyrolysis of low-cost Fe-salts with melamine(MA),porous alveolate Fe/g-C3N4 catalysts with high-density(Fe loading up to 17.7 wt%)and increased USCAD Fe sites were synthesized.The presence of a certain amount of S species in the Fe-salts/MA system plays an important role in the formation of USCAD S-Fe-salt/CN catalysts;the S species act as a"sacrificial carrier"to increase the dispersion of Fe species through Fe-S coordination and generate porous alveolate structure by escaping in the form of SO2 during pyrolysis.The S-Fe-salt/CN catalysts exhibit greatly promoted activity and reusability for degrading various organic pollutants in advanced oxidation processes compared to the corresponding Fe-salt/CN catalysts,due to the promoted accessibility of USCAD Fe sites by the porous alveolate structure.This S-assisted method exhibits good feasibility in a large variety of S species(thiourea,S powder,and NH4SCN)and Fe salts,providing a new avenue for the low-cost and large-scale synthesis of high-density USCAD metal/g-C3N4 catalysts.
基金supported by National Natural Science Foundation of China(Grant Numbers 11872339,11472248).
文摘In this paper,the degradation of mechanical properties of engineering cementitious composites(ECCs)at elevated temperatures and the failure of fiber are considered.A failure model under coupled thermo-mechanical loads for ECC is developed based on bond-based peridynamics.A semi-discrete model is constructed to describe fiber–matrix interactions and simulate thermal failure in ECC.The peridynamic differential operator(PDDO)is utilized for non-local modeling of thermal fluid flow and heat transfer.A multi-rate explicit time integration method is adopted to address thermo-mechanical coupling over different time scales.Model validation is achieved through simulating transient heat transfer in a homogeneous plate,with results aligning with analytical solutions.The damage behavior of a heated ECC plate in a borehole and under a fire scenario is analyzed,providing insights for enhancing fire resistance and high-temperature performance of ECC materials and structures.
基金supported by the State Key Program of National Natural Science Foundation of China(Grant No.21236008,21401017).
文摘Partial isomorphic substitution of iron in an Fe(BDC)(DMF,F)metal organic framework by manganese,cobalt,and nickel has been described for the first time.Specifically,different amounts of Mn,Co and Ni have been incorporated into the Fe-based framework during a solvothermal crystallization procedure.Several characterization techniques,including XRD,FT-IR,SEM,EDS,TG,XPS and ICP-AES,strongly support the effective incorporation of Mn,Ni and Co into material frameworks.The catalytic performance of these materials was examined in liquid-phase degradation of phenol at 35℃and near neutral pH of 6.2.The results show that the degradation efficiency can be evidently improved by the incorporation of Mn,while it can be inhibited by the incorporation of Ni.The incorporation of Co shows no remarkable influence on the degradation process.Moreover,the ratios of n(Fe)/n(Mn)in the bimetallic MOFs have a strong impact on the degradation process.The stability and reusability of these catalysts under mild conditions were also demonstrated in this study.This work illustrates the potential of bimetallic MOF structures in developing active heterogeneous catalysts for the degradation process of toxic compounds.
基金supported by the State Key Program of National Natural Science Foundation of China(grant no.21236008)the Fundamental Research Funds for the Central Universities(2342013DUT13RC(3)704).
文摘Titanium in different amounts has been successfully doped into the zirconium-based metal–organic framework UiO-66 via an in situ synthesis method,resulting in a series of hybrid UiO-66-nTi MOFs.These materials maintain a relatively high crystallinity and excellent structural stability.The addition of titanium has a significant effect on the crystal size and morphology of UiO-66.The UiO-66-nTi MOFs exhibit a sphere-like crystal morphology with a smaller crystal size and a rougher surface compared to the octahedral UiO-66 crystals.
基金supported by the National Natural Science Foundation of China(22278056)Liaoning Revitalization Talent Program(XLYC2008032)the Fundamental Research Funds for the Central Universities(DUT22LAB602)。
