The gold (Au) nanorods with various aspect ratios are obtained by a seed-media method in low pH growth solution. Transmission electron microscopy (TEM) and UV-visible spectrophotometry are utilized to characterize...The gold (Au) nanorods with various aspect ratios are obtained by a seed-media method in low pH growth solution. Transmission electron microscopy (TEM) and UV-visible spectrophotometry are utilized to characterize the Au nanorods, and the longitudinal absorption peak positions of Au nanorods show different shifting trends of the growth evolutions in various low pH (1~3) solutions. Other influential factors on the shape of Au nanorod are also systematically studied under low pH reaction condition. The positions of longitudinal peak shift between 600 nm and 900 nm, with the aspect ratios of Au nanorods varying from 2 to 5 both in the simulation and experimental results. The simulation results are in agreement with experimental ones.展开更多
Performance of the LSFD method is compared with conventional FD schemes. Generally, 9-point stencils for 2D cases and 27-point stencils for 3D cases are used for the approximation of the first and second order derivat...Performance of the LSFD method is compared with conventional FD schemes. Generally, 9-point stencils for 2D cases and 27-point stencils for 3D cases are used for the approximation of the first and second order derivatives obtained with conventional central difference schemes. When the same stencils are used, explicit LSFD formulations for approximation of the first and second order derivatives are presented. The LSFD formulations are actually a combination of conventional central difference schemes along relevant mesh lines. It has been found that LSFD formulations need much less iteration steps than the conventional FD schemes to converge, and the ratio of mesh spacing in the x and y directions is an important parameter in the LSFD application, with a great impact on stability of LSFD computation.展开更多
基金Project supported by the Nippon Sheet Glass Foundation for Materials Science and Engineering(Japan,January 2012)the Natural Science Foundation of Hubei Province of China(Grant No.2011CDB426)
文摘The gold (Au) nanorods with various aspect ratios are obtained by a seed-media method in low pH growth solution. Transmission electron microscopy (TEM) and UV-visible spectrophotometry are utilized to characterize the Au nanorods, and the longitudinal absorption peak positions of Au nanorods show different shifting trends of the growth evolutions in various low pH (1~3) solutions. Other influential factors on the shape of Au nanorod are also systematically studied under low pH reaction condition. The positions of longitudinal peak shift between 600 nm and 900 nm, with the aspect ratios of Au nanorods varying from 2 to 5 both in the simulation and experimental results. The simulation results are in agreement with experimental ones.
基金supported by the National Natural Science Foundation of China (Nos. 10872005, 10532010)
文摘Performance of the LSFD method is compared with conventional FD schemes. Generally, 9-point stencils for 2D cases and 27-point stencils for 3D cases are used for the approximation of the first and second order derivatives obtained with conventional central difference schemes. When the same stencils are used, explicit LSFD formulations for approximation of the first and second order derivatives are presented. The LSFD formulations are actually a combination of conventional central difference schemes along relevant mesh lines. It has been found that LSFD formulations need much less iteration steps than the conventional FD schemes to converge, and the ratio of mesh spacing in the x and y directions is an important parameter in the LSFD application, with a great impact on stability of LSFD computation.
文摘提出了一种未知信源数的高分辨 DOA 估计算法。该算法在未知信源数的情况下,利用线性预测(LP)法或 Pisarenko 法与 ASPECT 技术相结合来实现高分辨谱估计。该算法在消除 LP 法或 Pisarenko 法 DOA 估计中存在的伪峰的同时可判断出入射信源数,明显减小 DOA 估计算法的运算量,并可提高谱分辨力。计算机仿真结果证明了新算法理论的正确性和有效性。