In this paper, we propose a scheme for photon echo chirped detection process composed of additional modulation pulses to obtain controllable geometric phase. The geometric phases are observed and measured by a beat si...In this paper, we propose a scheme for photon echo chirped detection process composed of additional modulation pulses to obtain controllable geometric phase. The geometric phases are observed and measured by a beat signal between the photon echo field and the chirped field. The chirped detection model reveals that the period of the beat signal increases as the chirped rate and delay time increase. Additionally, a two-fold relationship between the modulation phase and the echo shift phase is obtained. The numerical simulations accord with the theoretical results obtained by the finite difference time domain(FDTD) method.展开更多
From the backscattering measurements of a two-point target consisting of two spheres,we discovered that the backward angular glint can be obtained by evaluating the derivative of the measured data of backscattering ec...From the backscattering measurements of a two-point target consisting of two spheres,we discovered that the backward angular glint can be obtained by evaluating the derivative of the measured data of backscattering echo relative phase versus incident angles. A representative vector model of N-point target consisting of N anisotropic point scatterers has been proposed to reveal the inherent law implied by the experimental phenomenon. Analytical arguments then demonstrate that, under certain conditions the equivalence can be found between the backward angular glint and the derivative of backscattering echo relative phase with respect to incident angles. This work is of particular value in deriving angular glint from backscattering measurement in the case of no bistatic scattering measurement capability.展开更多
Bubbly flows appear in many different industrial fields and the measurement of bubble sizes is crucial for understanding phase interactions. The ultrasound pulse echo can be used for a non-intrusive measurement of the...Bubbly flows appear in many different industrial fields and the measurement of bubble sizes is crucial for understanding phase interactions. The ultrasound pulse echo can be used for a non-intrusive measurement of the bubble surface position in one dimension even when there is no optical access to the bubble. A simultaneous measurement from two opposing directions gives the bubble size but has been performed only on single bubbles. This work applies the tracking technique, which allows a simultaneous measurement of multiple bubbles. The performance of the bubble size measurement was tested experimentally by comparing ultrasonic results with the sizes measured by a high-speed camera and also with metal cylinders. Possible sources of measurement uncertainty were analysed and discussed. The tested range of bubble sizes was up to 10 mm and the void fraction was lower than 1.25%.展开更多
为了提高电离层虚高测量精度,介绍了利用电离层回波相位实现高精度虚高测量的方法,并以CADI (Canadian Advanced Digital Ionosonde)电离层数字测高仪为研究平台,进行组合脉冲控制和回波相位测量分析,开展了一系列虚高测量实验,并与传...为了提高电离层虚高测量精度,介绍了利用电离层回波相位实现高精度虚高测量的方法,并以CADI (Canadian Advanced Digital Ionosonde)电离层数字测高仪为研究平台,进行组合脉冲控制和回波相位测量分析,开展了一系列虚高测量实验,并与传统的利用回波时间延迟的虚高测量方法进行了分析比较．实验结果表明,基于回波相位的测量分析方法与回波时延测量分析方法相比,其虚高测量精度高一个量级以上,这对精确反演电离层峰下电子浓度剖面及研究电离层精细结构具有重要意义．展开更多
基金Project supported by the Tianjin Research Program of Application Foundation and Advanced Technology,China(Grant No.15JCQNJC01100)
文摘In this paper, we propose a scheme for photon echo chirped detection process composed of additional modulation pulses to obtain controllable geometric phase. The geometric phases are observed and measured by a beat signal between the photon echo field and the chirped field. The chirped detection model reveals that the period of the beat signal increases as the chirped rate and delay time increase. Additionally, a two-fold relationship between the modulation phase and the echo shift phase is obtained. The numerical simulations accord with the theoretical results obtained by the finite difference time domain(FDTD) method.
文摘From the backscattering measurements of a two-point target consisting of two spheres,we discovered that the backward angular glint can be obtained by evaluating the derivative of the measured data of backscattering echo relative phase versus incident angles. A representative vector model of N-point target consisting of N anisotropic point scatterers has been proposed to reveal the inherent law implied by the experimental phenomenon. Analytical arguments then demonstrate that, under certain conditions the equivalence can be found between the backward angular glint and the derivative of backscattering echo relative phase with respect to incident angles. This work is of particular value in deriving angular glint from backscattering measurement in the case of no bistatic scattering measurement capability.
文摘Bubbly flows appear in many different industrial fields and the measurement of bubble sizes is crucial for understanding phase interactions. The ultrasound pulse echo can be used for a non-intrusive measurement of the bubble surface position in one dimension even when there is no optical access to the bubble. A simultaneous measurement from two opposing directions gives the bubble size but has been performed only on single bubbles. This work applies the tracking technique, which allows a simultaneous measurement of multiple bubbles. The performance of the bubble size measurement was tested experimentally by comparing ultrasonic results with the sizes measured by a high-speed camera and also with metal cylinders. Possible sources of measurement uncertainty were analysed and discussed. The tested range of bubble sizes was up to 10 mm and the void fraction was lower than 1.25%.
文摘为了提高电离层虚高测量精度,介绍了利用电离层回波相位实现高精度虚高测量的方法,并以CADI (Canadian Advanced Digital Ionosonde)电离层数字测高仪为研究平台,进行组合脉冲控制和回波相位测量分析,开展了一系列虚高测量实验,并与传统的利用回波时间延迟的虚高测量方法进行了分析比较．实验结果表明,基于回波相位的测量分析方法与回波时延测量分析方法相比,其虚高测量精度高一个量级以上,这对精确反演电离层峰下电子浓度剖面及研究电离层精细结构具有重要意义．
