中文摘要：

本文分析了单一透射式和反射式超声过程层析成像（UPT）的图像阈值对成像质量的影响和最优图像阈值的不确定性。通过将透射式UPT作为成像的基础,同时将反射重建图像作为补充信息,提出了一种结合透射式和反射式的双模式UPT,实现了连续成像时的图像阈值优化。设计基于以太网通讯的数字式8通道超声波发射、接收和自动切换系统,实现了自动扇形束扫描的工作模式,从而构建了一套运用于两相流动实时成像的数字化超声层析成像系统。利用该系统分别进行了管内气液分层流动和转动双圆柱的动态成像实验,结果表明,提出的双模式成像方法能自动给出合理的流型识别。

英文摘要：

The resultant impact of image threshold on reconstructed image quality and uncertainty of the optimal image threshold were analyzed for both transmission-mode and reflection-mode ultrasonic process tomography（UPT）.Then transmission and reflection coupled ultrasonic process tomography was proposed,in which the transmission-mode UPT was adopted as a base of imaging,and reflectionmode reconstructed image was integrated as complementary information to carry out an optimization of threshold during imaging.To carry out a validation,a digital 8-channel ultrasonic transmitting,receiving and automatic switching system based on Ethernet communication was designed,and the automatic fan-shaped beam scanning mode was realized.Afterwards,a digital ultrasonic tomography system for real-time imaging of two phase flow was constructed.The flow pattern of stratified flow with continuous injection of water and two rotating cylinders were investigated experimentally.The results showed that the proposed dual-mode imaging method facilitated automatic and reasonable flow pattern identification.