Highly ordered TiO_2 nanotube arrays(NTAs) on Si substrate possess broad applications due to its high surfaceto-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Her...Highly ordered TiO_2 nanotube arrays(NTAs) on Si substrate possess broad applications due to its high surfaceto-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Here, we report a simple and cost-effective high-field(90–180V) anodization method to grow highly ordered TiO_2 NTAs on Si substrate,and investigate the effect of anodization time, voltage, and fluoride content on the formation of TiO_2 NTAs. The current density–time curves, recorded during anodization processes, can be used to determine the optimum anodization time. It is found that the growth rate of TiO_2 NTAs is improved significantly under high field, which is nearly 8 times faster than that under low fields(40–60 V). The length and growth rate of the nanotubes are further increased with the increase of fluoride content in the electrolyte.展开更多
A hybrid method for synthesizing antenna's three dimensional(3D) pattern is proposed to obtain the low sidelobe feature of truncated cone conformal phased arrays. In this method,the elements of truncated cone conf...A hybrid method for synthesizing antenna's three dimensional(3D) pattern is proposed to obtain the low sidelobe feature of truncated cone conformal phased arrays. In this method,the elements of truncated cone conformal phased arrays are projected to the tangent plane in one generatrix of the truncated cone. Then two dimensional(2D) Chebyshev amplitude distribution optimization is respectively used in two mutual vertical directions of the tangent plane. According to the location of the elements,the excitation current amplitude distribution of each element on the conformal structure is derived reversely, then the excitation current amplitude is further optimized by using the genetic algorithm(GA). A truncated cone problem with 8×8 elements on it, and a3 D pattern desired side lobe level(SLL) up to 35 dB, is studied. By using the hybrid method, the optimal goal is accomplished with acceptable CPU time, which indicates that this hybrid method for the low sidelobe synthesis is feasible.展开更多
基金supported by National 863 Program 2011AA050518the Natural Science Foundation of China(Grant Nos.11174197,11574203,and 61234005)
文摘Highly ordered TiO_2 nanotube arrays(NTAs) on Si substrate possess broad applications due to its high surfaceto-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Here, we report a simple and cost-effective high-field(90–180V) anodization method to grow highly ordered TiO_2 NTAs on Si substrate,and investigate the effect of anodization time, voltage, and fluoride content on the formation of TiO_2 NTAs. The current density–time curves, recorded during anodization processes, can be used to determine the optimum anodization time. It is found that the growth rate of TiO_2 NTAs is improved significantly under high field, which is nearly 8 times faster than that under low fields(40–60 V). The length and growth rate of the nanotubes are further increased with the increase of fluoride content in the electrolyte.
基金supported by the Fundamental Research Funds for the Central Universities(YWF-13D2-XX-13)the National High-tech Research and Development Program(863 Program)(2008AA121802)
文摘A hybrid method for synthesizing antenna's three dimensional(3D) pattern is proposed to obtain the low sidelobe feature of truncated cone conformal phased arrays. In this method,the elements of truncated cone conformal phased arrays are projected to the tangent plane in one generatrix of the truncated cone. Then two dimensional(2D) Chebyshev amplitude distribution optimization is respectively used in two mutual vertical directions of the tangent plane. According to the location of the elements,the excitation current amplitude distribution of each element on the conformal structure is derived reversely, then the excitation current amplitude is further optimized by using the genetic algorithm(GA). A truncated cone problem with 8×8 elements on it, and a3 D pattern desired side lobe level(SLL) up to 35 dB, is studied. By using the hybrid method, the optimal goal is accomplished with acceptable CPU time, which indicates that this hybrid method for the low sidelobe synthesis is feasible.
