【作者】 张秋霞；

【导师】 石天明；

【作者基本信息】 中国石油大学 ， 信息与通信工程， 2010， 硕士

【摘要】 电阻层析成像( Electrical Resistance Tomography, ERT)技术是近年来发展起来的一种适用于两相流参数检测的新型检测技术。两相流参数通过ERT重建图像提取,为确保两相流参数的准确性,ERT重建图像的质量至关重要。本文针对提高重建图像质量的要求,对对称的双电流源激励模式下的图像成像算法进行了深入研究,并提出了改进方案。在本论文的研究中,主要完成了以下几方面的工作:1.总结了ERT技术的发展过程及研究现状,从系统组成、技术特点、发展方向等方面对ERT技术进行了综合评述。分析了ERT模型的建立、有限元网格的划分及正问题的求解方法,介绍了几种常用的ERT反问题成像算法。2.使用对称的双电流源激励下的测量电压数据,对几种不同流型进行图像重建,主要利用了灵敏度系数法(STM)和牛顿-拉夫森类算法(MNR),并对MNR算法进行了改进,引入了学习因子的概念,并应用局部自适应均值滤波方法进行ERT图像重建,有效地改善了重建图像质量。3.在MNR算法迭代逼近问题上,采取一种新型的逼近方式——正弦矢量逼近方法,充分利用双电流源激励不同相位差带来的有效信息,并取得了初步的成果。本文对双电源激励下的图像重建算法进行了深入研究,在原有算法的基础上进行了改进,对双电流源激励下ERT技术的发展作出了有益的探索。更多还原

【Abstract】 Electrical Resistance Tomography(ERT) is a new kind of Process Tomography(PT) which is suitable for the two-phase flow measurement. Two-phase parameter acquired from ERT reconstructed image, so the quality of reconstructed image is very important. This thesis presents a deeply research work of dual-current source image reconstruct algorithms in ERT research aimed at increasing the quality of reconstruction image, and proposes improving plans.The main contributions and works are as follows:1. Summarized the developing process and present status of the research on ERT, and summed up the ERT system structure, technique character, future development prospect and so on. Analyzed the established of ERT model, the division of finite element mesh and the solution of forward problem, and introduced several ERT reconstruction algorithms.2. Reconstructed images of several different flows with the measuring voltage data under symmetrical dual-current source using the Sensitivity Theory Method (STM) and the Modified Newton Raphson (MNR) method. Introduced the concept of learning-factor and used the method of adaptively calculated regional mean resistivity filter performed on some regional elements to improve the MNR algorithm, and improved the quality of reconstruction images effectively.3. Applied a new approximation method in the problem of MNR iterate approximation, sine vector approximation algorithm to used the effective information bring by different phase of dual-current source adequately, and obtained preliminary results.This thesis researched the image reconstruction algorithm under dual-current source deeply, improved old algorithm, formed a useful foundation for the future research work on dual-current source ERT development.更多还原