The precise tuning of magnetic nanoparticle size and magnetic domains,thereby shaping magnetic properties.However,the dynamic evolution mechanisms of magnetic domain configurations in relation to electromagnetic(EM)at...The precise tuning of magnetic nanoparticle size and magnetic domains,thereby shaping magnetic properties.However,the dynamic evolution mechanisms of magnetic domain configurations in relation to electromagnetic(EM)attenuation behavior remain poorly understood.To address this gap,a thermodynamically controlled periodic coordination strategy is proposed to achieve precise modulation of magnetic nanoparticle spacing.This approach unveils the evolution of magnetic domain configurations,progressing from individual to coupled and ultimately to crosslinked domain configurations.A unique magnetic coupling phenomenon surpasses the Snoek limit in low-frequency range,which is observed through micromagnetic simulation.The crosslinked magnetic configuration achieves effective low-frequency EM wave absorption at 3.68 GHz,encompassing nearly the entire C-band.This exceptional magnetic interaction significantly enhances radar camouflage and thermal insulation properties.Additionally,a robust gradient metamaterial design extends coverage across the full band(2–40 GHz),effectively mitigating the impact of EM pollution on human health and environment.This comprehensive study elucidates the evolution mechanisms of magnetic domain configurations,addresses gaps in dynamic magnetic modulation,and provides novel insights for the development of high-performance,low-frequency EM wave absorption materials.展开更多
Thermodynamic characteristics are of great importance for the performance of a high-temperature flow-rate control valve,as high-temperature environment may bring problems,such as blocking of spool and increasing of le...Thermodynamic characteristics are of great importance for the performance of a high-temperature flow-rate control valve,as high-temperature environment may bring problems,such as blocking of spool and increasing of leakage,to the valve.In this paper,a high-temperature flow-rate control valve,pilot-controlled by a pneumatic servo system is developed to control the fuel supply for scramjet engines.After introducing the construction and working principle,the thermodynamic mathematical models of the valve are built based on the heat transfer methods inside the valve.By using different boundary conditions,different methods of simulations are carried out and compared.The steady-state and transient temperature field distribution inside the valve body are predicted and temperatures at five interested points are measured.By comparing the simulation and experimental results,a reasonable 3D finite element analysis method is suggested to predict the thermodynamic characteristics of the high-temperature flow-rate control valve.展开更多
Covalent organic frameworks(COFs),a novel class of crystalline porous materials constructed by covalent bonds,possess ordered porous structures via thermodynamically controlled polymerization reactions.Because of thei...Covalent organic frameworks(COFs),a novel class of crystalline porous materials constructed by covalent bonds,possess ordered porous structures via thermodynamically controlled polymerization reactions.Because of their structurally diverse,regular pore structures,high surface area,and thermal stability can be functionally tailored through different synthetic methods to meet the needs of various applications including for secondary batteries.This review summarized recent efforts that have been devoted to designing and synthesizing COF-based materials for battery applications,including electrode materials,electrolytes,and separators.Unique characteristics of COFs allow for the rational design of targeted functions,suppression of side reactions,and promotion of ion transport for batteries.This review clarified recent research progress on COF materials for lithium-ion batteries,lithium-sulfur batteries,sodium-ion batteries,potassium-ion batteries and so on.This review pointed out the structure and chemical properties of COFs,as well as new strategies to improve battery performance.Furthermore,we concluded the major challenges and future trends of COF materials in electrochemical applications.It is hoped that this review will provide meaningful guidance for the development of COFs for alkali-ion batteries.展开更多
基金supported by the National Natural Science Foundation of China(22265021,52231007,and 12327804)the Aeronautical Science Foundation of China(2020Z056056003)Jiangxi Provincial Natural Science Foundation(20232BAB212004).
文摘The precise tuning of magnetic nanoparticle size and magnetic domains,thereby shaping magnetic properties.However,the dynamic evolution mechanisms of magnetic domain configurations in relation to electromagnetic(EM)attenuation behavior remain poorly understood.To address this gap,a thermodynamically controlled periodic coordination strategy is proposed to achieve precise modulation of magnetic nanoparticle spacing.This approach unveils the evolution of magnetic domain configurations,progressing from individual to coupled and ultimately to crosslinked domain configurations.A unique magnetic coupling phenomenon surpasses the Snoek limit in low-frequency range,which is observed through micromagnetic simulation.The crosslinked magnetic configuration achieves effective low-frequency EM wave absorption at 3.68 GHz,encompassing nearly the entire C-band.This exceptional magnetic interaction significantly enhances radar camouflage and thermal insulation properties.Additionally,a robust gradient metamaterial design extends coverage across the full band(2–40 GHz),effectively mitigating the impact of EM pollution on human health and environment.This comprehensive study elucidates the evolution mechanisms of magnetic domain configurations,addresses gaps in dynamic magnetic modulation,and provides novel insights for the development of high-performance,low-frequency EM wave absorption materials.
文摘Thermodynamic characteristics are of great importance for the performance of a high-temperature flow-rate control valve,as high-temperature environment may bring problems,such as blocking of spool and increasing of leakage,to the valve.In this paper,a high-temperature flow-rate control valve,pilot-controlled by a pneumatic servo system is developed to control the fuel supply for scramjet engines.After introducing the construction and working principle,the thermodynamic mathematical models of the valve are built based on the heat transfer methods inside the valve.By using different boundary conditions,different methods of simulations are carried out and compared.The steady-state and transient temperature field distribution inside the valve body are predicted and temperatures at five interested points are measured.By comparing the simulation and experimental results,a reasonable 3D finite element analysis method is suggested to predict the thermodynamic characteristics of the high-temperature flow-rate control valve.
基金supported by the National Key Research and Development Program of China(no.2022YFB2502000)the National Natural Science Foundation of China(nos.U21A2033251771076 and 52301266)+1 种基金Guangdong Basic and Applied Basic Research Foundation(nos.2020B1515120049 and 2021A1515010332)R&D Program in Key Areas of Guangdong Province(no.2020B0101030005).
文摘Covalent organic frameworks(COFs),a novel class of crystalline porous materials constructed by covalent bonds,possess ordered porous structures via thermodynamically controlled polymerization reactions.Because of their structurally diverse,regular pore structures,high surface area,and thermal stability can be functionally tailored through different synthetic methods to meet the needs of various applications including for secondary batteries.This review summarized recent efforts that have been devoted to designing and synthesizing COF-based materials for battery applications,including electrode materials,electrolytes,and separators.Unique characteristics of COFs allow for the rational design of targeted functions,suppression of side reactions,and promotion of ion transport for batteries.This review clarified recent research progress on COF materials for lithium-ion batteries,lithium-sulfur batteries,sodium-ion batteries,potassium-ion batteries and so on.This review pointed out the structure and chemical properties of COFs,as well as new strategies to improve battery performance.Furthermore,we concluded the major challenges and future trends of COF materials in electrochemical applications.It is hoped that this review will provide meaningful guidance for the development of COFs for alkali-ion batteries.
