针对基于声矢量传感器的空气流动速度(简称空速）测量问题，提出基于时空扩展MUSIC空速估计算法。首先，经过理论分析，得出在超音速气流形成的马赫锥内，任何一点有且仅有两个波阵面相叠加，这两个波阵面可以被认为是由两个相干“等效声源”产生的，在此项基础上，建立了声波在超音速稳定气流中的传播模型；其次，结合声矢量传感器的测量模型，基于时空扩展MUSIC算法实现超音速空速估计，并对测量模型进行了失效分析，推导了估计的CRB界；仿真实验结果验证了算法的有效性。
超音速气流 空速估计 声矢量传感器 失效分析 supersonic flow airspeed estimation acoustic vector sensor MUSIC MUSIC failure analysis
Author Affiliations
Abstract
1 Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, Massachusetts 02215, USA
2 Department of Physics, University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093, USA
3 Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA
4 e-mail: raveritt@ucsd.edu
We investigate the nonlinear response of terahertz (THz) metamaterial perfect absorbers consisting of electric split ring resonators on GaAs integrated with a polyimide spacer and gold ground plane. These perfect absorbers on bulk semi-insulating GaAs are characterized using high-field THz time-domain spectroscopy. The resonance frequency redshifts 20 GHz and the absorbance is reduced by 30% as the incident peak field is increased from 30 to 300 kV/cm. The nonlinear response arises from THz field driven interband transitions and intervalley scattering in the GaAs. To eliminate the Fresnel losses from the GaAs substrate, we design and fabricate a flexible metamaterialsaturable perfect absorber. The ability to create nonlinear absorbers enables appealing applications such as optical limiting and self-focusing.authors would like to thank the Boston University Photonics Center for technical support.
Far infrared or terahertz Far infrared or terahertz Metamaterials Metamaterials Nonlinear optical Nonlinear optical Photonics Research
2016, 4(3): 03000A16
