The shock-induced reaction mechanism and characteristics of Ni/Al system,considering an Al nanoparticle-embedded Ni single crystal,are investigated through molecular dynamics simulation.For the shock melting of Al nan...The shock-induced reaction mechanism and characteristics of Ni/Al system,considering an Al nanoparticle-embedded Ni single crystal,are investigated through molecular dynamics simulation.For the shock melting of Al nanoparticle,interfacial crystallization and dissolution are the main characteristics.The reaction degree of Al particle first increases linearly and then logarithmically with time driven by rapid mechanical mixing and following dissolution.The reaction rate increases with the decrease of particle diameter,however,the reaction is seriously hindered by interfacial crystallization when the diameter is lower than 9 nm in our simulations.Meanwhile,we found a negative exponential growth in the fraction of crystallized Al atoms,and the crystallinity of B2-NiAl(up to 20%)is positively correlated with the specific surface area of Al particle.This can be attributed to the formation mechanism of B2-NiAl by structural evolution of finite mixing layer near the collapsed interface.For shock melting of both Al particle and Ni matrix,the liquid-liquid phase inter-diffusion is the main reaction mechanism that can be enhanced by the formation of internal jet.In addition,the enhanced diffusion is manifested in the logarithmic growth law of mean square displacement,which results in an almost constant reaction rate similar to the mechanical mixing process.展开更多
To further understand the prediction skill for the interannual variability of the sea ice concentration(SIC)in specific regions of the Arctic,this paper evaluates the NCEP Climate Forecast System version 2(CFSv2),in p...To further understand the prediction skill for the interannual variability of the sea ice concentration(SIC)in specific regions of the Arctic,this paper evaluates the NCEP Climate Forecast System version 2(CFSv2),in predicting the autumn SIC and its interannual variability over the Barents–East Siberian Seas(BES).It is found that CFSv2 presents much better prediction skill for the September SIC over BES than the Arctic as a whole at 1–6-month leads,and high prediction skill for the interannual variability of the SIC over BES is displayed at 1–2-month leads after removing the linear trend.CFSv2 can reasonably reproduce the relationship between the SIC over BES in September and such factors as the surface air temperature(SAT),200-hPa geopotential height,sea surface temperature(SST),and North Atlantic Oscillation.In addition,it is found that the prescribed SIC initial condition in August as an input to CFSv2 is also essential.Therefore,the above atmospheric and oceanic factors,as well as an accurate initial condition of SIC,all contribute to a high prediction skill for SIC over BES in September.Based on a statistical prediction method,the contributions from individual predictability sources are further identified.The high prediction skill of CFSv2 for the interannual variability of SIC over BES is largely attributable to its accurate predictions of the SAT and SST,as well as a better initial condition of SIC.展开更多
基金supported by the State Key Program of National Natural Science Foundation of China(Grant No.12132003)State Key Laboratory of Explosion Science and Technology(Grant No.QNKT20-07)。
文摘The shock-induced reaction mechanism and characteristics of Ni/Al system,considering an Al nanoparticle-embedded Ni single crystal,are investigated through molecular dynamics simulation.For the shock melting of Al nanoparticle,interfacial crystallization and dissolution are the main characteristics.The reaction degree of Al particle first increases linearly and then logarithmically with time driven by rapid mechanical mixing and following dissolution.The reaction rate increases with the decrease of particle diameter,however,the reaction is seriously hindered by interfacial crystallization when the diameter is lower than 9 nm in our simulations.Meanwhile,we found a negative exponential growth in the fraction of crystallized Al atoms,and the crystallinity of B2-NiAl(up to 20%)is positively correlated with the specific surface area of Al particle.This can be attributed to the formation mechanism of B2-NiAl by structural evolution of finite mixing layer near the collapsed interface.For shock melting of both Al particle and Ni matrix,the liquid-liquid phase inter-diffusion is the main reaction mechanism that can be enhanced by the formation of internal jet.In addition,the enhanced diffusion is manifested in the logarithmic growth law of mean square displacement,which results in an almost constant reaction rate similar to the mechanical mixing process.
基金Supported by the National Key Research and Development Program of China(2022YFE0106800)National Natural Science Foundation of China(42230603)Innovation Group Project of the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(311021001)。
文摘To further understand the prediction skill for the interannual variability of the sea ice concentration(SIC)in specific regions of the Arctic,this paper evaluates the NCEP Climate Forecast System version 2(CFSv2),in predicting the autumn SIC and its interannual variability over the Barents–East Siberian Seas(BES).It is found that CFSv2 presents much better prediction skill for the September SIC over BES than the Arctic as a whole at 1–6-month leads,and high prediction skill for the interannual variability of the SIC over BES is displayed at 1–2-month leads after removing the linear trend.CFSv2 can reasonably reproduce the relationship between the SIC over BES in September and such factors as the surface air temperature(SAT),200-hPa geopotential height,sea surface temperature(SST),and North Atlantic Oscillation.In addition,it is found that the prescribed SIC initial condition in August as an input to CFSv2 is also essential.Therefore,the above atmospheric and oceanic factors,as well as an accurate initial condition of SIC,all contribute to a high prediction skill for SIC over BES in September.Based on a statistical prediction method,the contributions from individual predictability sources are further identified.The high prediction skill of CFSv2 for the interannual variability of SIC over BES is largely attributable to its accurate predictions of the SAT and SST,as well as a better initial condition of SIC.
