Research On Parallel Image Reconstruction Algorithm Of Electrical Capacitance Tomography

Process tomography (PT) technique is a new technique developed rapidly in recent years, which has great developmental potential and wide industrial application prospect in solving the measurement problem of multiphase flow. Electrical capacitance tomography (ECT) technique is a kind of PT technique based on the sensitive principle of capacitance, and it has been the most popular research direction and the main development technique of PT, due to its many distinct advantages such as no radiation, no invasion, high speed of response, simple structure, low cost, wide application range, better safety and so on. Though ECT has lots of advantages, there is still a lot of work to be done for practical use of the technique.This dissertation is based on the study of 12-electrode electrical capacitance tomography system for oil-water two-phase measurement. The main works and contributions of this dissertation are as follows:Firstly, it points out the important meaning of multiphase flow measurement to the science research and industry production based on the background of problem studied in this dissertation. It sums up the features of multiphase flow, sorts and parameters. It analyzes the current status and developing trend of the future multiphase measure.Secondly, the principle of the capacitance tomography is analysed and mathematical model of sensitivity field is proposed. Finite element model is proposed, and computation of sensitivity field is accomplished on the basis of this model. This model is correct and has better accuracy, which is proved by experiment.Thirdly, mathematics principle of image reconstruction algorithm is introduced.It's very important for getting parameters of PT, such as flow pattern, velocity, Sub-phase content, etc. Aiming at the soft field characteristic of ECT system, the influence of media distribution on potential distribution and capacitance between electrodes is discussed, also the sensitivity field.Fourthly, introduce several classical ECT image reconstruction algorithms, analyse and compare these excellences and disadvantages, in an attempt to inherit and improve.Finally, Genetic Algorithm and Neural Network are used as ECT image reconstruction algorithm. The simulation results show the method is effective and accurate for image reconstruction.