Research On Techniques Of Dual-mode Electrical Resistance & Capacitance Tomography

Electrical Tomography (ET) is a new measurement technique based on the theory of Electric-magnetic field. Due to the advantages of non-radiant, non-intrusive, rapid response and low cost, ET has the attractive developing potential in the field of industrial application and clinical diagnosis.Electrical Capacitance Tomography (ECT) and Electrical Resistance Tomography (ERT) are the two most developed ET methods nowadays. ERT is suitable to measure the conductive medium that is taken as the continuous phase in two-phase flow, while ECT is suitable to measure the non-conducting medium that is taken as the continuous phase in two-phase flow. In order to eliminate the conductivity limitation of the medium to be measured, a dual-mode electrical tomography (ERT/ECT) technique is proposed. Combined with ERT and ECT, the dual-mode tomography has advantages of acquiring more information and higher measurement accuracy.In this thesis, the mathematical modal and network circuit modal of the dual-mode array electrode, the sensor structure and parameter optimization and the system hardware are introduced and studied. Some main works and conclusions are as following.1. A unified mathematical modal of the ERT/ECT sensitive field is proposed based on the concept of complex conductance, and the solution of ERT/ECT forward problem is introduced using finite element method (FEM).2. On the basis of multi-terminal circuit theory, several excitation strategies and their independent measurements are analyzed. The relationship of the impedance, admittance, voltage conversion ratio and current conversion ratio derived from relative equivalent circuit of ERT/ECT sensitive field with certain excitation, as well as the relationship of the image reconstruction algorism are studied. And then a novel excitation/measuring method termed as"single electrode measurement of the common node multi-terminal circuit"that can decrease the dynamic range of the measurement signal is presented.3. ERT & ECT single mode and dual-mode array electrode are developed. Based on equivalent circuit of array electrode and FEM simulation, an objection function of...