讨论利用加权最大功率传输效率法(Weighted method of maximum power transmission efficiency,WMMPTE)实现多波束阵列天线的稀疏化,使得天线单元数目小于天线波束数数目。待设计天线与置于波束方向的测试天线形成无线功率传输系统,再利...讨论利用加权最大功率传输效率法(Weighted method of maximum power transmission efficiency,WMMPTE)实现多波束阵列天线的稀疏化,使得天线单元数目小于天线波束数数目。待设计天线与置于波束方向的测试天线形成无线功率传输系统,再利用WMMPTE优化可得到多波束阵列天线的最优激励分布。根据最优激励分布可进行阵列单元的稀疏化。通过工作频率为5.8 GHz的一维直线阵列和二维平面阵列为例介绍了稀疏化设计过程。模拟和实验表明,经WMMPTE优化后,利用3单元天线阵列可以实现4个波束、8单元天线阵列可以实现9个波束。展开更多
ZnO-TiO2 hybrid photoanodes were fabricated via the doctor-blade method by integrating vertically-grown sparse ZnO arrays with hydrothermal TiO2 nanoparticles. A special surface-coating technique was developed to depo...ZnO-TiO2 hybrid photoanodes were fabricated via the doctor-blade method by integrating vertically-grown sparse ZnO arrays with hydrothermal TiO2 nanoparticles. A special surface-coating technique was developed to deposit a thin TiO2 layer on the surface of ZnO rods. Microstructure, optical and photoelectrochemical performance of the hybrid photoanodes were investigated. The denser ZnO array exhibited bad filling behavior of nanoparticles in the interspace of ZnO rods, strong scattering and low conversion efficiency (0.27%). The sparser array showed a much better integrated microstructure, improved transmittance and high conversion efficiency (2.68%). The surface modification of ZnO rods by the TiO2 thin layer was found useful in improving the interfacial microstructure between the ZnO rod and the TiO2 bulk film, and the total conversion efficiency of 3.01% was achieved, higher than that of the pure TiO2 nanoparticle cell (2.93%). The increased scattering effects on the incident light, the enhanced electron transportation at TiO2/dye/electrolyte interface, and the inhabited recombination were responsible for this improvement.展开更多
文摘讨论利用加权最大功率传输效率法(Weighted method of maximum power transmission efficiency,WMMPTE)实现多波束阵列天线的稀疏化,使得天线单元数目小于天线波束数数目。待设计天线与置于波束方向的测试天线形成无线功率传输系统,再利用WMMPTE优化可得到多波束阵列天线的最优激励分布。根据最优激励分布可进行阵列单元的稀疏化。通过工作频率为5.8 GHz的一维直线阵列和二维平面阵列为例介绍了稀疏化设计过程。模拟和实验表明,经WMMPTE优化后,利用3单元天线阵列可以实现4个波束、8单元天线阵列可以实现9个波束。
基金supported by the National Basic Research Program of China (Grant Nos. 2009CB623304 and 2011CB013805the National Natural Science Foundation of China (Grant Nos. 51072214 and 51002174)
文摘ZnO-TiO2 hybrid photoanodes were fabricated via the doctor-blade method by integrating vertically-grown sparse ZnO arrays with hydrothermal TiO2 nanoparticles. A special surface-coating technique was developed to deposit a thin TiO2 layer on the surface of ZnO rods. Microstructure, optical and photoelectrochemical performance of the hybrid photoanodes were investigated. The denser ZnO array exhibited bad filling behavior of nanoparticles in the interspace of ZnO rods, strong scattering and low conversion efficiency (0.27%). The sparser array showed a much better integrated microstructure, improved transmittance and high conversion efficiency (2.68%). The surface modification of ZnO rods by the TiO2 thin layer was found useful in improving the interfacial microstructure between the ZnO rod and the TiO2 bulk film, and the total conversion efficiency of 3.01% was achieved, higher than that of the pure TiO2 nanoparticle cell (2.93%). The increased scattering effects on the incident light, the enhanced electron transportation at TiO2/dye/electrolyte interface, and the inhabited recombination were responsible for this improvement.
