For a mesoscopic L-C circuit,besides the Louisell's quantization scheme in which electric charge q andelectric current I are respectively quantized as the coordinate operator Q and momentum operator P,in this pape...For a mesoscopic L-C circuit,besides the Louisell's quantization scheme in which electric charge q andelectric current I are respectively quantized as the coordinate operator Q and momentum operator P,in this paperwe propose a new quantization scheme in the context of number-phase quantization through the standard Lagrangianformalism.The comparison between this number-phase quantization with the Josephson junction's Cooper pair number-phase-difference quantization scheme is made.展开更多
针对现有相位差分法在低信噪比条件下估计线性调频(LFM)信号瞬时频率性能明显下降的问题,提出了一种改进的基于N阶相位差分法的瞬时频率估计算法。首先,在相位重构的基础上,针对信噪比阈值引起的频率突变问题,设置自适应的累积增量门限...针对现有相位差分法在低信噪比条件下估计线性调频(LFM)信号瞬时频率性能明显下降的问题,提出了一种改进的基于N阶相位差分法的瞬时频率估计算法。首先,在相位重构的基础上,针对信噪比阈值引起的频率突变问题,设置自适应的累积增量门限来确定频率突变位置,并利用循环迭代进行插值修正;然后,通过高阶的相位差分估计瞬时频率,以充分利用重构相位包含的跳变信息,并采用迭代变权最小二乘的方法进行线性拟合;最后,引入自适应的思想来处理不同频率的输入信号,增强处理低频输入信号的能力。仿真结果表明,相对于现有相位差分法,改进N阶相位差分法在保持低运算量的同时提升了抗噪性能,对输入信噪比的下限要求降低了约4 d B。展开更多
A phase-sensitive optical time domain reflectometer （φ-OTDR） based on a 120°-phase-difference Michelson in- terferometer is proposed. The Michelson interferometer with arm difference of 4m is used to test the ...A phase-sensitive optical time domain reflectometer （φ-OTDR） based on a 120°-phase-difference Michelson in- terferometer is proposed. The Michelson interferometer with arm difference of 4m is used to test the phase difference between the Rayleigh scattering from two sections of the fiber. A new demodulation method called the inverse transmission matrix demodulation scheme is utilized to demodulate the distributed phase from the backward scattering along the long fiber, The experimental results show that the 120°-phase-difference inter- ferometer φ-OTDR can detect the phase along the 3km fiber, and the acoustic signal within the whole human hearing range of 20 Hz-20 kHz is reproduced accurately and quickly.展开更多
基金The project supported by the President Foundation of the Chinese Academy of Sciences
文摘For a mesoscopic L-C circuit,besides the Louisell's quantization scheme in which electric charge q andelectric current I are respectively quantized as the coordinate operator Q and momentum operator P,in this paperwe propose a new quantization scheme in the context of number-phase quantization through the standard Lagrangianformalism.The comparison between this number-phase quantization with the Josephson junction's Cooper pair number-phase-difference quantization scheme is made.
文摘针对现有相位差分法在低信噪比条件下估计线性调频(LFM)信号瞬时频率性能明显下降的问题,提出了一种改进的基于N阶相位差分法的瞬时频率估计算法。首先,在相位重构的基础上,针对信噪比阈值引起的频率突变问题,设置自适应的累积增量门限来确定频率突变位置,并利用循环迭代进行插值修正;然后,通过高阶的相位差分估计瞬时频率,以充分利用重构相位包含的跳变信息,并采用迭代变权最小二乘的方法进行线性拟合;最后,引入自适应的思想来处理不同频率的输入信号,增强处理低频输入信号的能力。仿真结果表明,相对于现有相位差分法,改进N阶相位差分法在保持低运算量的同时提升了抗噪性能,对输入信噪比的下限要求降低了约4 d B。
基金Supported by the National Natural Science Foundation of China under Grant Nos U0934001 and 11076028the Science and Technology Commission of Shanghai Municipality under Grant Nos 11DZ1140202 and 13XD1425400the Pudong New Area Science and Technology Development Fund of China under Grant No PKJ2012-D04
文摘A phase-sensitive optical time domain reflectometer （φ-OTDR） based on a 120°-phase-difference Michelson in- terferometer is proposed. The Michelson interferometer with arm difference of 4m is used to test the phase difference between the Rayleigh scattering from two sections of the fiber. A new demodulation method called the inverse transmission matrix demodulation scheme is utilized to demodulate the distributed phase from the backward scattering along the long fiber, The experimental results show that the 120°-phase-difference inter- ferometer φ-OTDR can detect the phase along the 3km fiber, and the acoustic signal within the whole human hearing range of 20 Hz-20 kHz is reproduced accurately and quickly.
