In this work,we study the interaction between two colloidal particles in a liquid crystal that is in the isotropic phase.The interaction is caused by surface-induced polarization of the liquid crystal molecules in the...In this work,we study the interaction between two colloidal particles in a liquid crystal that is in the isotropic phase.The interaction is caused by surface-induced polarization of the liquid crystal molecules in the vicinity of the particles.We find that the interaction is short-ranged in both 2D and 3D geometry.Under symmetric homeotropic anchoring conditions,the interaction is repulsive.While under anti-symmetric homeotropic anchoring conditions,the interaction is repulsive at short distances but attractive at intermediate distances.The particle size has a strong impact on the effective interaction force.展开更多
For investigating efficiently the stagnation kinetic-process of Z-pinch,we develop a novel modified electrostatic implicit particle-in-cell algorithm in radial one-dimension for Z-pinch simulation in which a small-ang...For investigating efficiently the stagnation kinetic-process of Z-pinch,we develop a novel modified electrostatic implicit particle-in-cell algorithm in radial one-dimension for Z-pinch simulation in which a small-angle cumulative binary collision algorithm is used.In our algorithm,the electric field in z-direction is solved by a parallel electrode-plate model,the azimuthal magnetic field is obtained by Ampere’s law,and the term for charged particle gyromotion is approximated by the cross product of the averaged velocity and magnetic field.In simulation results of 2 MA deuterium plasma shell Zpinch,the mass-center implosion trajectory agrees generally with that obtained by one-dimensional MHD simulation,and the plasma current also closely aligns with the external current.The phase space diagrams and radial-velocity probability distributions of ions and electrons are obtained.The main kinetic characteristic of electron motion is thermal equilibrium and oscillation,which should be oscillated around the ions,while that of ion motion is implosion inwards.In the region of stagnation radius,the radial-velocity probability distribution of ions transits from the non-equilibrium to equilibrium state with the current increasing,while of electrons is basically the equilibrium state.When the initial ion density and current peak are not high enough,the ions may not reach their thermal equilibrium state through collisions even in its stagnation phase.展开更多
Lymph node targeting is a commonly used strategy for particulate vaccines,particularly for Pickering emulsions.However,extensive research on the internal delivery mechanisms of these emulsions,especially the complex i...Lymph node targeting is a commonly used strategy for particulate vaccines,particularly for Pickering emulsions.However,extensive research on the internal delivery mechanisms of these emulsions,especially the complex intercellular interactions of deformable Pickering emulsions,has been surprisingly sparse.This gap in knowledge holds significant potential for enhancing vaccine efficacy.This study aims to address this by summarizing the process of lymph-node-targeting transport and introducing a dissipative particle dynamics simulation method to evaluate the dynamic processes within cell tissue.The transport of Pickering emulsions in skeletal muscle tissue is specifically investigated as a case study.Various factors impacting the transport process are explored,including local cellular tissue environmental factors and the properties of the Pickering emulsion itself.The simulation results primarily demonstrate that an increase in radial repulsive interaction between emulsion particles can decrease the transport efficiency.Additionally,larger intercellular gaps also diminish the transport efficiency of emulsion droplet particles due to the increased motion complexity within the intricate transport space compared to a single channel.This study sheds light on the nuanced interplay between engineered and biological systems influencing the transport dynamics of Pickering emulsions.Such insights hold valuable potential for optimizing transport processes in practical biomedical applications such as drug delivery.Importantly,the desired transport efficiency varies depending on the specific application.For instance,while a more rapid transport might be crucial for lymph-node-targeted drug delivery,certain applications requiring a slower release of active components could benefit from the reduced transport efficiency observed with increased particle repulsion or larger intercellular gaps.展开更多
The production and utilization of high-energetic explosives often pose a range of safety hazards,with sensitivity being a key factor in evaluating these risks.To investigate how temperature,particle size,and air humid...The production and utilization of high-energetic explosives often pose a range of safety hazards,with sensitivity being a key factor in evaluating these risks.To investigate how temperature,particle size,and air humidity affect the responsiveness of commonly used high-energetic explosives,a series of BAM(Bundesanstalt für Materialforschung und-prüfung)impact and friction sensitivity tests were carried out to determine the critical impact energy and critical load pressure of four representative high-energetic explosives(RDX,HMX,PETN and CL-20)under different temperatures,particle sizes,and air humidity conditions.The experimental findings facilitated an examination of temperature and particle size affecting the sensitivity of high-energetic explosives,along with an assessment of the influence of air humidity on sensitivity testing.The results clearly indicate that high-energetic explosives display a substantial decline in critical reaction energy when subjected to micrometre-sized particles and an air humidity level of 45%at a temperature of 90℃.Furthermore,it was noted that the critical reaction energy of high-energetic explosives diminishes with an increase in temperature within 25℃−90℃.In the same vein,as the particle sizes of high-energetic explosives increase,so does the critical reaction energy for micrometre-sized particles.High air humidity significantly affects the sensitivity testing of high-energetic explosives,emphasizing the importance of refraining from conducting sensitivity tests in such conditions.展开更多
The Tibetan Plateau,known as the“Third Pole”,is currently in a state of perturbation caused by intensified human activity.In this study,56 samples were obtained at the five sampling sites in typical area of Lhasa ci...The Tibetan Plateau,known as the“Third Pole”,is currently in a state of perturbation caused by intensified human activity.In this study,56 samples were obtained at the five sampling sites in typical area of Lhasa city and their physical and chemical properties were investigated by TEM/EDS,STXM,and NEXAFS spectroscopy.After careful examination of 3387single particles,the results showed that Fe should be one of the most frequent metal elements.The Fe-containing single particles in irregular shape and micrometer size was about7.8%and might be mainly from local sources.Meanwhile,the Fe was located on the subsurface of single particles and might be existed in the form of iron oxide.Interestingly,the core-shell structure of iron-containing particles were about 38.8%and might be present as single-,dual-or triple-core shell structure and multi-core shell structure with the Fe/Si ratios of 17.5,10.5,2.9 and 1.2,respectively.Meanwhile,iron and manganese were found to coexist with identical distributions in the single particles,which might induce a synergistic effect between iron and manganese in catalytic oxidation.Finally,the solid spherical structure of Fe-containing particles without an external layer were about 53.4%.The elements of Fe and Mn were co-existed,and might be presented as iron oxide-manganese oxide-silica composite.Moreover,the ferrous and ferric forms of iron might be co-existed.Such information can be valuable in expanding our understanding of Fe-containing particles in the Tibetan Plateau atmosphere.展开更多
WC particles reinforced CoCrFeNiMo high-entropy alloy(HEA)composite coatings were prepared on Cr12MoV steel successfully by laser cladding technology to improve the wear resistance of substrates.Effect of WC content o...WC particles reinforced CoCrFeNiMo high-entropy alloy(HEA)composite coatings were prepared on Cr12MoV steel successfully by laser cladding technology to improve the wear resistance of substrates.Effect of WC content on microstructure and wear property of the composite coatings was studied in detail.Large numbers of carbides with four main types:primary carbide crystals,eutectic structures,massive crystals growing along the periphery of the remaining WC particles and incompletely fused WC particles,were found to exist in the WC/CoCrFeNiMo composite coatings.With increasing WC content,the microhardness of coatings is gradually improved while the average friction coefficients follow the opposite trend due to solid solution strengthening and second phase strengthening effect.The maximum microhardness and minimum friction coefficient are HV_(0.2)689.7 and 0.72,respectively,for the composite coating with 30 wt.%WC,the wear resistance of the substrate is improved significantly,the wear mechanisms are spalling wear and abrasive wear due to their high microhardness.展开更多
Polybrominated biphenyl ethers(PBDEs)and polycyclic aromatic hydrocarbons(PAHs)are commonly detected contaminants at e-waste recycling sites.Against the conventional wisdom that PBDEs and PAHs are highly immobile and ...Polybrominated biphenyl ethers(PBDEs)and polycyclic aromatic hydrocarbons(PAHs)are commonly detected contaminants at e-waste recycling sites.Against the conventional wisdom that PBDEs and PAHs are highly immobile and persist primarily in shallowsurface soils,increasing evidence shows that these compounds can leach into the groundwater.Herein,we compare the leachabilities of PBDEs vs.PAHs from contaminated soils collected at an e-waste recycling site in Tianjin,China.Considerable amounts of BDE-209(0.3–2 ng/L)and phenanthrene(42–106 ng/L),the most abundant PBDE and PAH at the site,are detected in the effluents of columns packed with contaminated soils,with the specific concentrations varying with hydrodynamic and solution chemistry conditions.Interestingly,the leaching potential of BDE-209 appears to be closely related to the release of colloidal mineral particles,whereas the leachability of phenanthrene correlates well with the concentration of dissolved organic carbon in the effluent,but showing essentially no correlation with the concentration of mineral particles.The surprisingly different trends of the leachability observed between BDE-209 and phenanthrene is counterintuitive,as PBDEs and PAHs often co-exist at e-waste recycling sites(particularly at the sites wherein incineration is being practiced)and share many similarities in terms of physicochemical properties.One possible explanation is that due to its extremely low solubility,BDE-209 predominantly exists in free-phase(i.e.,as solid(nano)particles),whereas the more soluble phenanthrene is mainly sorbed to soil organic matter.Findings in this study underscore the need to better understand the mobility of highly hydrophobic organic contaminants at contaminated sites for improved risk management.展开更多
Densely distributed coherent nanoparticles(DCN)in steel matrix can enhance the work-hardening ability and ductility of steel simultaneously.All the routes to this end can be generally classified into the liquid-solid ...Densely distributed coherent nanoparticles(DCN)in steel matrix can enhance the work-hardening ability and ductility of steel simultaneously.All the routes to this end can be generally classified into the liquid-solid route and the solid-solid route.However,the formation of DCN structures in steel requires long processes and complex steps.So far,obtaining steel with coherent particle enhancement in a short time remains a bottleneck,and some necessary steps remain unavoidable.Here,we show a high-efficiency liquid-phase refining process reinforced by a dynamic magnetic field.Ti-Y-Mn-O particles had an average size of around(3.53±1.21)nm and can be obtained in just around 180 s.These small nanoparticles were coherent with the matrix,implying no accumulated dislocations between the particles and the steel matrix.Our findings have a potential application for improving material machining capacity,creep resistance,and radiation resistance.展开更多
The multi-objective particle swarm optimization algorithm(MOPSO)is widely used to solve multi-objective optimization problems.In the article,amulti-objective particle swarm optimization algorithmbased on decomposition...The multi-objective particle swarm optimization algorithm(MOPSO)is widely used to solve multi-objective optimization problems.In the article,amulti-objective particle swarm optimization algorithmbased on decomposition and multi-selection strategy is proposed to improve the search efficiency.First,two update strategies based on decomposition are used to update the evolving population and external archive,respectively.Second,a multiselection strategy is designed.The first strategy is for the subspace without a non-dominated solution.Among the neighbor particles,the particle with the smallest penalty-based boundary intersection value is selected as the global optimal solution and the particle far away fromthe search particle and the global optimal solution is selected as the personal optimal solution to enhance global search.The second strategy is for the subspace with a non-dominated solution.In the neighbor particles,two particles are randomly selected,one as the global optimal solution and the other as the personal optimal solution,to enhance local search.The third strategy is for Pareto optimal front(PF)discontinuity,which is identified by the cumulative number of iterations of the subspace without non-dominated solutions.In the subsequent iteration,a new probability distribution is used to select from the remaining subspaces to search.Third,an adaptive inertia weight update strategy based on the dominated degree is designed to further improve the search efficiency.Finally,the proposed algorithmis compared with fivemulti-objective particle swarm optimization algorithms and five multi-objective evolutionary algorithms on 22 test problems.The results show that the proposed algorithm has better performance.展开更多
To improve the wettability of hypereutectic Al−60Si alloy and enhance the mechanical properties of the joints,Al−60Si alloy was joined by ultrasonic soldering with Sn-9Zn solder,and a sound joint with in-situ Si parti...To improve the wettability of hypereutectic Al−60Si alloy and enhance the mechanical properties of the joints,Al−60Si alloy was joined by ultrasonic soldering with Sn-9Zn solder,and a sound joint with in-situ Si particle reinforcement was obtained.The oxide film of Al−60Si alloy at the interface was identified by transmission electron microscopy(TEM)analysis as amorphous Al_(2)O_(3).The oxide of Si particles in the base metal was also alumina.The oxide film of Al−60Si alloy was observed to be removed by ultrasonic vibration instead of holding treatment.Si particle-reinforced joints(35.7 vol.%)were obtained by increasing the ultrasonication time.The maximum shear strength peaked at 99.5 MPa for soldering at 330℃with an ultrasonic vibration time of 50 s.A model of forming of Si particles reinforced joint under the ultrasound was proposed,and ultrasonic vibration was considered to promote the dissolution of Al and migration of Si particles.展开更多
Terrain Aided Navigation(TAN)technology has become increasingly important due to its effectiveness in environments where Global Positioning System(GPS)is unavailable.In recent years,TAN systems have been extensively r...Terrain Aided Navigation(TAN)technology has become increasingly important due to its effectiveness in environments where Global Positioning System(GPS)is unavailable.In recent years,TAN systems have been extensively researched for both aerial and underwater navigation applications.However,many TAN systems that rely on recursive Unmanned Aerial Vehicle(UAV)position estimation methods,such as Extended Kalman Filters(EKF),often face challenges with divergence and instability,particularly in highly non-linear systems.To address these issues,this paper proposes and investigates a hybrid two-stage TAN positioning system for UAVs that utilizes Particle Filter.To enhance the system’s robustness against uncertainties caused by noise and to estimate additional system states,a Fuzzy Particle Filter(FPF)is employed in the first stage.This approach introduces a novel terrain composite feature that enables a fuzzy expert system to analyze terrain non-linearities and dynamically adjust the number of particles in real-time.This design allows the UAV to be efficiently localized in GPS-denied environments while also reducing the computational complexity of the particle filter in real-time applications.In the second stage,an Error State Kalman Filter(ESKF)is implemented to estimate the UAV’s altitude.The ESKF is chosen over the conventional EKF method because it is more suitable for non-linear systems.Simulation results demonstrate that the proposed fuzzy-based terrain composite method achieves high positional accuracy while reducing computational time and memory usage.展开更多
Assessing the behaviour and concentration of waste pollutants deposited between two parallel plates is essential for effective environmental management.Determining the effectiveness of treatment methods in reducing po...Assessing the behaviour and concentration of waste pollutants deposited between two parallel plates is essential for effective environmental management.Determining the effectiveness of treatment methods in reducing pollution scales is made easier by analysing waste discharge concentrations.The waste discharge concentration analysis is useful for assessing how effectively wastewater treatment techniques reduce pollution levels.This study aims to explore the Casson micropolar fluid flow through two parallel plates with the influence of pollutant concentration and thermophoretic particle deposition.To explore the mass and heat transport features,thermophoretic particle deposition and thermal radiation are considered.The governing equations are transformed into ordinary differential equations with the help of suitable similarity transformations.The Runge-Kutta-Fehlberg’s fourthfifth order technique and shooting procedure are used to solve the reduced set of equations and boundary conditions.The integration of a neural network model based on the Levenberg-Marquardt algorithm serves to improve the accuracy of predictions and optimize the analysis of parameters.Graphical outcomes are displayed to analyze the characteristics of the relevant dimensionless parameters in the current problem.Results reveal that concentration upsurges as the micropolar parameter increases.The concentration reduces with an upsurge in the thermophoretic parameter.An upsurge in the external pollutant source variation and the local pollutant external source parameters enhances mass transport.The surface drag force declines for improved values of porosity and micropolar parameters.展开更多
The wireless signals emitted by base stations serve as a vital link connecting people in today’s society and have been occupying an increasingly important role in real life.The development of the Internet of Things(I...The wireless signals emitted by base stations serve as a vital link connecting people in today’s society and have been occupying an increasingly important role in real life.The development of the Internet of Things(IoT)relies on the support of base stations,which provide a solid foundation for achieving a more intelligent way of living.In a specific area,achieving higher signal coverage with fewer base stations has become an urgent problem.Therefore,this article focuses on the effective coverage area of base station signals and proposes a novel Evolutionary Particle Swarm Optimization(EPSO)algorithm based on collective prediction,referred to herein as ECPPSO.Introducing a new strategy called neighbor-based evolution prediction(NEP)addresses the issue of premature convergence often encountered by PSO.ECPPSO also employs a strengthening evolution(SE)strategy to enhance the algorithm’s global search capability and efficiency,ensuring enhanced robustness and a faster convergence speed when solving complex optimization problems.To better adapt to the actual communication needs of base stations,this article conducts simulation experiments by changing the number of base stations.The experimental results demonstrate thatunder the conditionof 50 ormore base stations,ECPPSOconsistently achieves the best coverage rate exceeding 95%,peaking at 99.4400%when the number of base stations reaches 80.These results validate the optimization capability of the ECPPSO algorithm,proving its feasibility and effectiveness.Further ablative experiments and comparisons with other algorithms highlight the advantages of ECPPSO.展开更多
文摘为了评价PIC猪的胴体性状和肉质性状,试验屠宰了健康的PIC猪9头,测定了其胴体性状、肉质性状和肌肉成分等相关指标,并分析了各性状间的相关性。结果表明,宰前活重为123.78 kg的PIC猪,屠宰率为75.58%,瘦肉率为60.8%,平均背膘厚25.62 mm,眼肌面积45.95 cm 2,滴水损失2.14%,嫩度43.56N,肌内脂肪含量2.23%,总氨基酸含量20.3%,饱和脂肪酸含量41.54%,总不饱和脂肪酸含量58.44%。性状间相关性分析表明,PIC猪的宰前活重与屠宰率呈显著正相关(P<0.05),肌内脂肪与MUFA呈极显著正相关(P<0.01),与PUFA呈极显著负相关(P<0.01),与水分呈显著负相关(P<0.05)。肌内脂肪与水分间的相关系数为-0.718,二者间线性模型Y=-0.9985x+75.299,决定系数R^(2)为0.5153。
基金support from the National Natural Science Foundation of China under Grant No.12004317Fundamental Research Funds for Central Universities of China under Grant No.20720200072111 project No.B16029.
文摘In this work,we study the interaction between two colloidal particles in a liquid crystal that is in the isotropic phase.The interaction is caused by surface-induced polarization of the liquid crystal molecules in the vicinity of the particles.We find that the interaction is short-ranged in both 2D and 3D geometry.Under symmetric homeotropic anchoring conditions,the interaction is repulsive.While under anti-symmetric homeotropic anchoring conditions,the interaction is repulsive at short distances but attractive at intermediate distances.The particle size has a strong impact on the effective interaction force.
基金the graduated students Zhixing Feng,Xiaoqiang Zhang,and Deli Fang for their excellent works to develop the PIC simulation codes of Z-pinch.This research was partly supported by the National Natural Science Foundation of China(Grant Nos.11675025 and 11135007)the Innovation Project of China Academy of Engineering Physics(Grant No.CX2019030).
文摘For investigating efficiently the stagnation kinetic-process of Z-pinch,we develop a novel modified electrostatic implicit particle-in-cell algorithm in radial one-dimension for Z-pinch simulation in which a small-angle cumulative binary collision algorithm is used.In our algorithm,the electric field in z-direction is solved by a parallel electrode-plate model,the azimuthal magnetic field is obtained by Ampere’s law,and the term for charged particle gyromotion is approximated by the cross product of the averaged velocity and magnetic field.In simulation results of 2 MA deuterium plasma shell Zpinch,the mass-center implosion trajectory agrees generally with that obtained by one-dimensional MHD simulation,and the plasma current also closely aligns with the external current.The phase space diagrams and radial-velocity probability distributions of ions and electrons are obtained.The main kinetic characteristic of electron motion is thermal equilibrium and oscillation,which should be oscillated around the ions,while that of ion motion is implosion inwards.In the region of stagnation radius,the radial-velocity probability distribution of ions transits from the non-equilibrium to equilibrium state with the current increasing,while of electrons is basically the equilibrium state.When the initial ion density and current peak are not high enough,the ions may not reach their thermal equilibrium state through collisions even in its stagnation phase.
基金supported by the National Natural Science Foundation of China(22373104 and 22293024)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(21821005)+1 种基金supported by the National Key Research and Development Program of China(2021YFE020527)support by the Distinguished Young Scholars of the National Natural Science Foundation of China(T2222022).
文摘Lymph node targeting is a commonly used strategy for particulate vaccines,particularly for Pickering emulsions.However,extensive research on the internal delivery mechanisms of these emulsions,especially the complex intercellular interactions of deformable Pickering emulsions,has been surprisingly sparse.This gap in knowledge holds significant potential for enhancing vaccine efficacy.This study aims to address this by summarizing the process of lymph-node-targeting transport and introducing a dissipative particle dynamics simulation method to evaluate the dynamic processes within cell tissue.The transport of Pickering emulsions in skeletal muscle tissue is specifically investigated as a case study.Various factors impacting the transport process are explored,including local cellular tissue environmental factors and the properties of the Pickering emulsion itself.The simulation results primarily demonstrate that an increase in radial repulsive interaction between emulsion particles can decrease the transport efficiency.Additionally,larger intercellular gaps also diminish the transport efficiency of emulsion droplet particles due to the increased motion complexity within the intricate transport space compared to a single channel.This study sheds light on the nuanced interplay between engineered and biological systems influencing the transport dynamics of Pickering emulsions.Such insights hold valuable potential for optimizing transport processes in practical biomedical applications such as drug delivery.Importantly,the desired transport efficiency varies depending on the specific application.For instance,while a more rapid transport might be crucial for lymph-node-targeted drug delivery,certain applications requiring a slower release of active components could benefit from the reduced transport efficiency observed with increased particle repulsion or larger intercellular gaps.
基金supported by National Natural Science Foundation of China(No.12272184).
文摘The production and utilization of high-energetic explosives often pose a range of safety hazards,with sensitivity being a key factor in evaluating these risks.To investigate how temperature,particle size,and air humidity affect the responsiveness of commonly used high-energetic explosives,a series of BAM(Bundesanstalt für Materialforschung und-prüfung)impact and friction sensitivity tests were carried out to determine the critical impact energy and critical load pressure of four representative high-energetic explosives(RDX,HMX,PETN and CL-20)under different temperatures,particle sizes,and air humidity conditions.The experimental findings facilitated an examination of temperature and particle size affecting the sensitivity of high-energetic explosives,along with an assessment of the influence of air humidity on sensitivity testing.The results clearly indicate that high-energetic explosives display a substantial decline in critical reaction energy when subjected to micrometre-sized particles and an air humidity level of 45%at a temperature of 90℃.Furthermore,it was noted that the critical reaction energy of high-energetic explosives diminishes with an increase in temperature within 25℃−90℃.In the same vein,as the particle sizes of high-energetic explosives increase,so does the critical reaction energy for micrometre-sized particles.High air humidity significantly affects the sensitivity testing of high-energetic explosives,emphasizing the importance of refraining from conducting sensitivity tests in such conditions.
基金supported by the National Natural Science Foundation of China(No.21677116)the environmental risk management and control of industrial solid waste recycling process in low temperature and low pressure with anoxic environment(No.2019YFC190410304)+2 种基金the Second Tibetan Plateau Scientific Expedition and Research Program(Nos.2019QZKK0603,2019QZKK0605)the Central Government Supports the Phased Achievement Funding of Local University Projects(ZCKJZ[2022]No.1,[2021]No.1,[2020]No.1 and[2019]No.44)the"High level talents"training program for Postgraduates of Tibet University,2021-GSP-B016。
文摘The Tibetan Plateau,known as the“Third Pole”,is currently in a state of perturbation caused by intensified human activity.In this study,56 samples were obtained at the five sampling sites in typical area of Lhasa city and their physical and chemical properties were investigated by TEM/EDS,STXM,and NEXAFS spectroscopy.After careful examination of 3387single particles,the results showed that Fe should be one of the most frequent metal elements.The Fe-containing single particles in irregular shape and micrometer size was about7.8%and might be mainly from local sources.Meanwhile,the Fe was located on the subsurface of single particles and might be existed in the form of iron oxide.Interestingly,the core-shell structure of iron-containing particles were about 38.8%and might be present as single-,dual-or triple-core shell structure and multi-core shell structure with the Fe/Si ratios of 17.5,10.5,2.9 and 1.2,respectively.Meanwhile,iron and manganese were found to coexist with identical distributions in the single particles,which might induce a synergistic effect between iron and manganese in catalytic oxidation.Finally,the solid spherical structure of Fe-containing particles without an external layer were about 53.4%.The elements of Fe and Mn were co-existed,and might be presented as iron oxide-manganese oxide-silica composite.Moreover,the ferrous and ferric forms of iron might be co-existed.Such information can be valuable in expanding our understanding of Fe-containing particles in the Tibetan Plateau atmosphere.
基金Project(2021YFC2801904)supported by the National Key R&D Program of ChinaProject(KY10100230067)supported by the Basic Product Innovation Research Project,China+3 种基金Projects(52271130,52305344)supported by the National Natural Science Foundation of ChinaProjects(ZR2020ME017,ZR2020QE186)supported by the Natural Science Foundation of Shandong Province,ChinaProjects(AMGM2024F11,AMGM2021F10,AMGM2023F06)supported by the Science Fund of Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai,ChinaProject(KY90200210015)supported by Leading Scientific Research Project of China National Nuclear Corporation(CNNC),China。
文摘WC particles reinforced CoCrFeNiMo high-entropy alloy(HEA)composite coatings were prepared on Cr12MoV steel successfully by laser cladding technology to improve the wear resistance of substrates.Effect of WC content on microstructure and wear property of the composite coatings was studied in detail.Large numbers of carbides with four main types:primary carbide crystals,eutectic structures,massive crystals growing along the periphery of the remaining WC particles and incompletely fused WC particles,were found to exist in the WC/CoCrFeNiMo composite coatings.With increasing WC content,the microhardness of coatings is gradually improved while the average friction coefficients follow the opposite trend due to solid solution strengthening and second phase strengthening effect.The maximum microhardness and minimum friction coefficient are HV_(0.2)689.7 and 0.72,respectively,for the composite coating with 30 wt.%WC,the wear resistance of the substrate is improved significantly,the wear mechanisms are spalling wear and abrasive wear due to their high microhardness.
基金supported by the National Key Research and Development Program of China(No.2019YFC1804202)the National Natural Science Foundation of China(Nos.22020102004 and 22125603)+1 种基金Tianjin Municipal Science and Technology Bureau(No.21JCZDJC00280)the Fundamental Research Funds for the Central Universities,and the Ministry of Education of China(No.T2017002).
文摘Polybrominated biphenyl ethers(PBDEs)and polycyclic aromatic hydrocarbons(PAHs)are commonly detected contaminants at e-waste recycling sites.Against the conventional wisdom that PBDEs and PAHs are highly immobile and persist primarily in shallowsurface soils,increasing evidence shows that these compounds can leach into the groundwater.Herein,we compare the leachabilities of PBDEs vs.PAHs from contaminated soils collected at an e-waste recycling site in Tianjin,China.Considerable amounts of BDE-209(0.3–2 ng/L)and phenanthrene(42–106 ng/L),the most abundant PBDE and PAH at the site,are detected in the effluents of columns packed with contaminated soils,with the specific concentrations varying with hydrodynamic and solution chemistry conditions.Interestingly,the leaching potential of BDE-209 appears to be closely related to the release of colloidal mineral particles,whereas the leachability of phenanthrene correlates well with the concentration of dissolved organic carbon in the effluent,but showing essentially no correlation with the concentration of mineral particles.The surprisingly different trends of the leachability observed between BDE-209 and phenanthrene is counterintuitive,as PBDEs and PAHs often co-exist at e-waste recycling sites(particularly at the sites wherein incineration is being practiced)and share many similarities in terms of physicochemical properties.One possible explanation is that due to its extremely low solubility,BDE-209 predominantly exists in free-phase(i.e.,as solid(nano)particles),whereas the more soluble phenanthrene is mainly sorbed to soil organic matter.Findings in this study underscore the need to better understand the mobility of highly hydrophobic organic contaminants at contaminated sites for improved risk management.
基金financially supported by the National Natural Science Foundation of China(No.51771125)the Sichuan Province Science and Technology Support Program(No.2020YFG0102)。
文摘Densely distributed coherent nanoparticles(DCN)in steel matrix can enhance the work-hardening ability and ductility of steel simultaneously.All the routes to this end can be generally classified into the liquid-solid route and the solid-solid route.However,the formation of DCN structures in steel requires long processes and complex steps.So far,obtaining steel with coherent particle enhancement in a short time remains a bottleneck,and some necessary steps remain unavoidable.Here,we show a high-efficiency liquid-phase refining process reinforced by a dynamic magnetic field.Ti-Y-Mn-O particles had an average size of around(3.53±1.21)nm and can be obtained in just around 180 s.These small nanoparticles were coherent with the matrix,implying no accumulated dislocations between the particles and the steel matrix.Our findings have a potential application for improving material machining capacity,creep resistance,and radiation resistance.
基金supported by National Natural Science Foundations of China(nos.12271326,62102304,61806120,61502290,61672334,61673251)China Postdoctoral Science Foundation(no.2015M582606)+2 种基金Industrial Research Project of Science and Technology in Shaanxi Province(nos.2015GY016,2017JQ6063)Fundamental Research Fund for the Central Universities(no.GK202003071)Natural Science Basic Research Plan in Shaanxi Province of China(no.2022JM-354).
文摘The multi-objective particle swarm optimization algorithm(MOPSO)is widely used to solve multi-objective optimization problems.In the article,amulti-objective particle swarm optimization algorithmbased on decomposition and multi-selection strategy is proposed to improve the search efficiency.First,two update strategies based on decomposition are used to update the evolving population and external archive,respectively.Second,a multiselection strategy is designed.The first strategy is for the subspace without a non-dominated solution.Among the neighbor particles,the particle with the smallest penalty-based boundary intersection value is selected as the global optimal solution and the particle far away fromthe search particle and the global optimal solution is selected as the personal optimal solution to enhance global search.The second strategy is for the subspace with a non-dominated solution.In the neighbor particles,two particles are randomly selected,one as the global optimal solution and the other as the personal optimal solution,to enhance local search.The third strategy is for Pareto optimal front(PF)discontinuity,which is identified by the cumulative number of iterations of the subspace without non-dominated solutions.In the subsequent iteration,a new probability distribution is used to select from the remaining subspaces to search.Third,an adaptive inertia weight update strategy based on the dominated degree is designed to further improve the search efficiency.Finally,the proposed algorithmis compared with fivemulti-objective particle swarm optimization algorithms and five multi-objective evolutionary algorithms on 22 test problems.The results show that the proposed algorithm has better performance.
基金financial support from the National Natural Science Foundation of China(Nos.52275385,U2167216)Sichuan Province Science and Technology Support Program,China(No.2022YFG0086).
文摘To improve the wettability of hypereutectic Al−60Si alloy and enhance the mechanical properties of the joints,Al−60Si alloy was joined by ultrasonic soldering with Sn-9Zn solder,and a sound joint with in-situ Si particle reinforcement was obtained.The oxide film of Al−60Si alloy at the interface was identified by transmission electron microscopy(TEM)analysis as amorphous Al_(2)O_(3).The oxide of Si particles in the base metal was also alumina.The oxide film of Al−60Si alloy was observed to be removed by ultrasonic vibration instead of holding treatment.Si particle-reinforced joints(35.7 vol.%)were obtained by increasing the ultrasonication time.The maximum shear strength peaked at 99.5 MPa for soldering at 330℃with an ultrasonic vibration time of 50 s.A model of forming of Si particles reinforced joint under the ultrasound was proposed,and ultrasonic vibration was considered to promote the dissolution of Al and migration of Si particles.
文摘Terrain Aided Navigation(TAN)technology has become increasingly important due to its effectiveness in environments where Global Positioning System(GPS)is unavailable.In recent years,TAN systems have been extensively researched for both aerial and underwater navigation applications.However,many TAN systems that rely on recursive Unmanned Aerial Vehicle(UAV)position estimation methods,such as Extended Kalman Filters(EKF),often face challenges with divergence and instability,particularly in highly non-linear systems.To address these issues,this paper proposes and investigates a hybrid two-stage TAN positioning system for UAVs that utilizes Particle Filter.To enhance the system’s robustness against uncertainties caused by noise and to estimate additional system states,a Fuzzy Particle Filter(FPF)is employed in the first stage.This approach introduces a novel terrain composite feature that enables a fuzzy expert system to analyze terrain non-linearities and dynamically adjust the number of particles in real-time.This design allows the UAV to be efficiently localized in GPS-denied environments while also reducing the computational complexity of the particle filter in real-time applications.In the second stage,an Error State Kalman Filter(ESKF)is implemented to estimate the UAV’s altitude.The ESKF is chosen over the conventional EKF method because it is more suitable for non-linear systems.Simulation results demonstrate that the proposed fuzzy-based terrain composite method achieves high positional accuracy while reducing computational time and memory usage.
文摘Assessing the behaviour and concentration of waste pollutants deposited between two parallel plates is essential for effective environmental management.Determining the effectiveness of treatment methods in reducing pollution scales is made easier by analysing waste discharge concentrations.The waste discharge concentration analysis is useful for assessing how effectively wastewater treatment techniques reduce pollution levels.This study aims to explore the Casson micropolar fluid flow through two parallel plates with the influence of pollutant concentration and thermophoretic particle deposition.To explore the mass and heat transport features,thermophoretic particle deposition and thermal radiation are considered.The governing equations are transformed into ordinary differential equations with the help of suitable similarity transformations.The Runge-Kutta-Fehlberg’s fourthfifth order technique and shooting procedure are used to solve the reduced set of equations and boundary conditions.The integration of a neural network model based on the Levenberg-Marquardt algorithm serves to improve the accuracy of predictions and optimize the analysis of parameters.Graphical outcomes are displayed to analyze the characteristics of the relevant dimensionless parameters in the current problem.Results reveal that concentration upsurges as the micropolar parameter increases.The concentration reduces with an upsurge in the thermophoretic parameter.An upsurge in the external pollutant source variation and the local pollutant external source parameters enhances mass transport.The surface drag force declines for improved values of porosity and micropolar parameters.
基金supported by the National Natural Science Foundation of China(Nos.62272418,62102058)Basic Public Welfare Research Program of Zhejiang Province(No.LGG18E050011)the Major Open Project of Key Laboratory for Advanced Design and Intelligent Computing of the Ministry of Education under Grant ADIC2023ZD001,National Undergraduate Training Program on Innovation and Entrepreneurship(No.202410345054).
文摘The wireless signals emitted by base stations serve as a vital link connecting people in today’s society and have been occupying an increasingly important role in real life.The development of the Internet of Things(IoT)relies on the support of base stations,which provide a solid foundation for achieving a more intelligent way of living.In a specific area,achieving higher signal coverage with fewer base stations has become an urgent problem.Therefore,this article focuses on the effective coverage area of base station signals and proposes a novel Evolutionary Particle Swarm Optimization(EPSO)algorithm based on collective prediction,referred to herein as ECPPSO.Introducing a new strategy called neighbor-based evolution prediction(NEP)addresses the issue of premature convergence often encountered by PSO.ECPPSO also employs a strengthening evolution(SE)strategy to enhance the algorithm’s global search capability and efficiency,ensuring enhanced robustness and a faster convergence speed when solving complex optimization problems.To better adapt to the actual communication needs of base stations,this article conducts simulation experiments by changing the number of base stations.The experimental results demonstrate thatunder the conditionof 50 ormore base stations,ECPPSOconsistently achieves the best coverage rate exceeding 95%,peaking at 99.4400%when the number of base stations reaches 80.These results validate the optimization capability of the ECPPSO algorithm,proving its feasibility and effectiveness.Further ablative experiments and comparisons with other algorithms highlight the advantages of ECPPSO.
