设x_n的密度函数为f(x),X∈R^d,f_n(x)=(nh^d)^(-1)sum from i-1 to n k((x-x_i)/h)为f的核估计,其中0<h=h(n)→0,K绝对可积且∫K(x)dx=1,记J_n=∫|f_n(x)-f(x)|dx,本文对样本{x_n}为α混合或φ混合时.给出J_n依概率趋于0,完全收敛于...设x_n的密度函数为f(x),X∈R^d,f_n(x)=(nh^d)^(-1)sum from i-1 to n k((x-x_i)/h)为f的核估计,其中0<h=h(n)→0,K绝对可积且∫K(x)dx=1,记J_n=∫|f_n(x)-f(x)|dx,本文对样本{x_n}为α混合或φ混合时.给出J_n依概率趋于0,完全收敛于0的充分条件。展开更多
Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation.The latter is critical in controlling the overall efficiency in one-step ph...Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation.The latter is critical in controlling the overall efficiency in one-step photoexcitation systems.In this study,a nanosized BiVO4/Bi0.6Y0.4VO4 solid solution was prepared by a coprecipitation method following with hydrothermal or calcination processes.The S-scheme heterojunction was fabricated by in-situ pressure-induced transformations of bismuth vanadate from the tetragonal zircon phase to the monoclinic scheelite phase,which led to the formation of BiVO4 nanoparticles with a diameter of approximately 5 nm on the surface of BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4)/Bi_(0.6)Y_(0.4)VO_(4) with S-scheme heterojunctions showed significantly enhanced photocatalytic overall water splitting activity compared with using bare BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4).Characterization of the carrier dynamics demonstrated that a superior carrier separation through S-type heterojunctions might have caused the enhanced overall water splitting(OWS)activity.Surface photovoltage spectra and the results of selective photodeposition experiments indicated that the photogenerated holes mainly migrated to the BiVO4 nanoparticles in the heterojunction.This confirmed that the charge transfer route corresponds to an S-scheme rather than a type-II heterojunction mechanism under light illumination.This study presents a facile and efficient strategy to construct S-scheme heterojunctions through a pressure-induced phase transition.The results demonstrated that S-scheme junctions composed of different crystalline phases can boost the carrier separation capacity and eventually improve the photocatalytic OWS activity.展开更多
In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the fille...In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the filler metal. The influence of gap size and bonding time on the joints was investigated. For example, complete isothermal solidification time for 40μm gap size was obtained as 45 min. In the case of lack of completion of isothermal solidification step, the remained molten interlayer cooled in the bonding zone under non-equilibrium condition andγ–γ′ eutectic phase formed in that area. The relationship between gap size and holding time was not linear. With the increase in gap size, eutectic phase width became thicker. In the diffusion affected zone, a much larger amount of alloying elements were observed reaching a peak. These peaks might be due to the formation of boride or silicide intermetallic. With the increase in gap size, the time required for bonding will increase, so the alloying elements have more time for diffusion and distribution in farther areas. As a result, concentrations of alloying elements decreased slightly with the increase in the gap size. The present bi-phasic model did not properly predict the complete isothermal solidification time for IN-738LC-AMS 4777-IN-738LC TLP bonding system.展开更多
文摘设x_n的密度函数为f(x),X∈R^d,f_n(x)=(nh^d)^(-1)sum from i-1 to n k((x-x_i)/h)为f的核估计,其中0<h=h(n)→0,K绝对可积且∫K(x)dx=1,记J_n=∫|f_n(x)-f(x)|dx,本文对样本{x_n}为α混合或φ混合时.给出J_n依概率趋于0,完全收敛于0的充分条件。
文摘Step-scheme(S-scheme)heterojunctions in photocatalysts can provide novel and practical insight on promoting photogenerated carrier separation.The latter is critical in controlling the overall efficiency in one-step photoexcitation systems.In this study,a nanosized BiVO4/Bi0.6Y0.4VO4 solid solution was prepared by a coprecipitation method following with hydrothermal or calcination processes.The S-scheme heterojunction was fabricated by in-situ pressure-induced transformations of bismuth vanadate from the tetragonal zircon phase to the monoclinic scheelite phase,which led to the formation of BiVO4 nanoparticles with a diameter of approximately 5 nm on the surface of BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4)/Bi_(0.6)Y_(0.4)VO_(4) with S-scheme heterojunctions showed significantly enhanced photocatalytic overall water splitting activity compared with using bare BiVO_(4)/Bi_(0.6)Y_(0.4)VO_(4).Characterization of the carrier dynamics demonstrated that a superior carrier separation through S-type heterojunctions might have caused the enhanced overall water splitting(OWS)activity.Surface photovoltage spectra and the results of selective photodeposition experiments indicated that the photogenerated holes mainly migrated to the BiVO4 nanoparticles in the heterojunction.This confirmed that the charge transfer route corresponds to an S-scheme rather than a type-II heterojunction mechanism under light illumination.This study presents a facile and efficient strategy to construct S-scheme heterojunctions through a pressure-induced phase transition.The results demonstrated that S-scheme junctions composed of different crystalline phases can boost the carrier separation capacity and eventually improve the photocatalytic OWS activity.
文摘In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the filler metal. The influence of gap size and bonding time on the joints was investigated. For example, complete isothermal solidification time for 40μm gap size was obtained as 45 min. In the case of lack of completion of isothermal solidification step, the remained molten interlayer cooled in the bonding zone under non-equilibrium condition andγ–γ′ eutectic phase formed in that area. The relationship between gap size and holding time was not linear. With the increase in gap size, eutectic phase width became thicker. In the diffusion affected zone, a much larger amount of alloying elements were observed reaching a peak. These peaks might be due to the formation of boride or silicide intermetallic. With the increase in gap size, the time required for bonding will increase, so the alloying elements have more time for diffusion and distribution in farther areas. As a result, concentrations of alloying elements decreased slightly with the increase in the gap size. The present bi-phasic model did not properly predict the complete isothermal solidification time for IN-738LC-AMS 4777-IN-738LC TLP bonding system.
