Image Reconstruction Algorithms Based On Least Squares Algorithms For Electrical Capacitance Tomography

Multiphase flow parameters detection technology is urgently needed to develop. However, due to multi-phase flow exists the relative velocity and interface effects and other issues, leading to the detection of multiphase flow parameters is very difficult. In recent many years, studies have found the Process Tomography (PT) technique has wide industrial application prospect and great developmental potential in solving the measurement problem of multiphase flow. Because of many advantages such as simple structure, low cost, wide application field, better safety and non-invade, Electrical Capacitance Tomography (ECT) is the most popular research direction and the main development in flow imaging technique, However, due to electrical capacitance tomography technique is not mature enough to meet the industrial applications standards, it is further needed to research.This paper is based on the study of capacitive sensing mechanism of 12-electrode electrical capacitance tomography system, and mainly discusses some problems of image reconstruction by electrical capacitance tomography technology, to solve the"soft-field"nature and the ill-posed problem in electrical capacitance tomography technology, on the basis of combining the least squares method and iterative algorithm, a least squares image reconstruction algorithm restricted by iterative method for electrical capacitance tomography is presented. The main works and contributions of this paper are as follows:Firstly, connecting with the topic background, the important significance of multiphase flow measurement to the science research and industry production is pointed out, this paper analyzes the features, parameters of multiphase flow, and describes the basic principles and the development status of the process tomography system. Secondly, this paper analyzes the composition and working principle of electrical capacitance tomography system, introduces mathematics principle and significance of image reconstruction algorithm, and summarizes and generalizes the basic characteristics and development status of electrical capacitance tomography system.Thirdly, it systematically introduces Least Squares(LS) algorithms, describes the basic idea of this method, and analyzes the mathematical model and the whole process in image reconstruction, to improve the deficiencies of this method, on the basis of combining the least squares method and iterative algorithm, this paper establishes a mathematical model of image reconstruction. Experiments show that this mathematical model is correct, and it is able to meet the requirements of image reconstruction.Finally, a least squares image reconstruction algorithm restricted by iterative method for electrical capacitance tomography is presented, and its convergence characteristic is proved, this algorithm makes the iteration step is optimal on the premise of convergence. Experimental results show that the quality of image reconstructed is improved.