阵列幅相误差会显著降低麦克风阵列的声源定位性能,因此对麦克风阵列的幅度和相位进行良好校准至关重要。文章针对近场麦克风阵列,引入三维多重信号分类(Multiple Signal Classification,MUSIC)近场算法,对基于特征结构的阵列幅度和相...阵列幅相误差会显著降低麦克风阵列的声源定位性能,因此对麦克风阵列的幅度和相位进行良好校准至关重要。文章针对近场麦克风阵列,引入三维多重信号分类(Multiple Signal Classification,MUSIC)近场算法,对基于特征结构的阵列幅度和相位校正方法进行改进。改进后的校正方法不再局限于特定阵列的拓扑结构,可以实现近场校正,具有较高的定位估计精度。展开更多
The microstructure of hypoeutectic Al-9.21wt.%Si alloy solidified under 5.5 GPa was studied. The results show that the solidification microstructure is refined. The primary a phase is the extended solid solution. The ...The microstructure of hypoeutectic Al-9.21wt.%Si alloy solidified under 5.5 GPa was studied. The results show that the solidification microstructure is refined. The primary a phase is the extended solid solution. The solid solubility of Si in α phase is up to 8.26wt.%. The growth mode of the α phase is cellular, and this cellular growth mechanism is interpreted in terms of the decrease of the diffusivity and the extended solid solution under high pressure. By calculation, it can be known that the the diffusivity of solute in the liquid under normal pressure is as high as two hundred times that under high pressure. The microhardness of the hypoeutectic Al-Si alloy solidified under high pressure is higher than that of solidified under normal pressure. After annealing, Si precipitates from the solid solution, the microhardness of the alloy decrease, but, still higher than that of solidified under normal pressure.展开更多
文摘阵列幅相误差会显著降低麦克风阵列的声源定位性能,因此对麦克风阵列的幅度和相位进行良好校准至关重要。文章针对近场麦克风阵列,引入三维多重信号分类(Multiple Signal Classification,MUSIC)近场算法,对基于特征结构的阵列幅度和相位校正方法进行改进。改进后的校正方法不再局限于特定阵列的拓扑结构,可以实现近场校正,具有较高的定位估计精度。
基金supported by the National Natural Science Foundation of China(grant No.59571040)
文摘The microstructure of hypoeutectic Al-9.21wt.%Si alloy solidified under 5.5 GPa was studied. The results show that the solidification microstructure is refined. The primary a phase is the extended solid solution. The solid solubility of Si in α phase is up to 8.26wt.%. The growth mode of the α phase is cellular, and this cellular growth mechanism is interpreted in terms of the decrease of the diffusivity and the extended solid solution under high pressure. By calculation, it can be known that the the diffusivity of solute in the liquid under normal pressure is as high as two hundred times that under high pressure. The microhardness of the hypoeutectic Al-Si alloy solidified under high pressure is higher than that of solidified under normal pressure. After annealing, Si precipitates from the solid solution, the microhardness of the alloy decrease, but, still higher than that of solidified under normal pressure.
