Image reconstruction method along electrical field centre lines using a modified mixed normalization model for electrical capacitance tomography

During the process of image reconstruction for electrical capacitance tomography (ECT), normalization of measured capacitance values is carried out with the low and high permittvity. The parallel normalization model (PM) and series normalization model (SM) are most commonly used. In recent years, using different combination methods such as electrical field centre line (EFCL) for PM and SM, several mixed normalization models (MM) obtained better description of the permittivity distribution of the two-phase media in pipe. In this paper, a new method of determining the weight factors of the PM and SM sensitivity matrix to form the MM sensitivity matrix is proposed. This weight factors are determined according to the minimum distance between the element and EFCL. Simulation and experimental test were carried out and the results show that both the accuracy and the shape fidelity can be improved obviously.