Y 0.9-xGd xEu 0.1BO 3 phosphors were synthesized by spray drying (SD) method, and the results were compared with those by conventional solid state (SS) and citrate gel (CG) methods. The PL intensity of phospho...Y 0.9-xGd xEu 0.1BO 3 phosphors were synthesized by spray drying (SD) method, and the results were compared with those by conventional solid state (SS) and citrate gel (CG) methods. The PL intensity of phosphors increases with the increase of x value in Y 0.9-xGd xEu 0.1BO 3 (prepared by SD) due to an energy migration process like Gd 3+-(Gd 3+) n-Eu 3+ occurred in the material. Compared with the latter two methods, the phosphor particles prepared by spray drying method have a better morphology, such as homogeneous size (about 1～3 μm) with spherical shape and smooth surface. Furthermore, the spray drying-derived phosphors have higher photoluminescence (PL) intensity than those by citrate gel method, but still a little lower than those by the solid state method.展开更多
Active Flux is a third order accurate numerical method which evolves cell averages and point values at cell interfaces independently.It naturally uses a continuous reconstruction,but is stable when applied to hyperbol...Active Flux is a third order accurate numerical method which evolves cell averages and point values at cell interfaces independently.It naturally uses a continuous reconstruction,but is stable when applied to hyperbolic problems.In this work,the Active Flux method is extended for the first time to a nonlinear hyperbolic system of balance laws,namely,to the shallow water equations with bottom topography.We demonstrate how to achieve an Active Flux method that is well-balanced,positivity preserving,and allows for dry states in one spatial dimension.Because of the continuous reconstruction all these properties are achieved using new approaches.To maintain third order accuracy,we also propose a novel high-order approximate evolution operator for the update of the point values.A variety of test problems demonstrates the good performance of the method even in presence of shocks.展开更多
文摘Y 0.9-xGd xEu 0.1BO 3 phosphors were synthesized by spray drying (SD) method, and the results were compared with those by conventional solid state (SS) and citrate gel (CG) methods. The PL intensity of phosphors increases with the increase of x value in Y 0.9-xGd xEu 0.1BO 3 (prepared by SD) due to an energy migration process like Gd 3+-(Gd 3+) n-Eu 3+ occurred in the material. Compared with the latter two methods, the phosphor particles prepared by spray drying method have a better morphology, such as homogeneous size (about 1～3 μm) with spherical shape and smooth surface. Furthermore, the spray drying-derived phosphors have higher photoluminescence (PL) intensity than those by citrate gel method, but still a little lower than those by the solid state method.
基金supported by the Deutsche Forschungsgemeinschaft(DFG)through project 429491391(BA 6878/1-1).
文摘Active Flux is a third order accurate numerical method which evolves cell averages and point values at cell interfaces independently.It naturally uses a continuous reconstruction,but is stable when applied to hyperbolic problems.In this work,the Active Flux method is extended for the first time to a nonlinear hyperbolic system of balance laws,namely,to the shallow water equations with bottom topography.We demonstrate how to achieve an Active Flux method that is well-balanced,positivity preserving,and allows for dry states in one spatial dimension.Because of the continuous reconstruction all these properties are achieved using new approaches.To maintain third order accuracy,we also propose a novel high-order approximate evolution operator for the update of the point values.A variety of test problems demonstrates the good performance of the method even in presence of shocks.
