Study Of Electromagnetic Tomography Image Reconstruction Based On Finite Element And Genetic Algorithm

Electromagnetic Tomography (EMT) is a new Process Tomography Technology based on electromagnetic induction principle, which has the features of non-contact and non-intrusive when measuring. Its measurement precision will not be restricted by the factor that the electric pole must have a good contact with the measured object. There will not be current coupling between measured object and equipment when using EMT method, so polarization phenomenon is avoided and the measuring system working steadily for a long time is formed easily. The EMT have the features of strong ability of anti-noise, no action of ionizing radiation, no leakage current, non-invasive and low cost on medically. So, it has comprehensive applications in many domains and great project application potential, it has been increasingly become a preceding study special as the international application of electromagnetic technology.Based on EMT system structure, date detection and common image reconstruction algorithm existing, the paper does research in the method of electromagnetic tomography image reconstruction. In accordance with these defects, that there is hardly analytical solution of forward problem because the structure of the detected objects is mostly very complicated and the medium character is almost different, furthermore, the image reconstruction of electromagnetic imaging is a question of nonlinear inverse problem itself and the imaging quality of the algorithm existed is very poor in image reconstruction, then, a new kind of method is proposed based on the method of finite element and improved genetic algorithm to realize electromagnetic tomography image reconstruction.Based on the mathematical modal of conductive region, the paper has analyzed and solved EMT forward problem using the finite-element method, it provides realizable prior information for image reconstruction. Using triangle subdivision and three vertices linear interpolation function, which is a first order linear function. By means of large finite-element simulation software Ansoft, the conductive region is analyzed. Aiming at EMT conductive region, exciting current, exciting frequency and the property of object affect magnetic induction intensity, and the effect of location and material of object on detection voltage have analyzed detailedly. To standard genetic algorithm, facing the defects of premature phenomena and the phenomenon of swing and slow convergence when close to optimal solution, fitness function and genetic operation are improved. By this way, the optimal solution has been found and the imaging quality has been guaranteed better.Finally, the EMT technology is simulated based on Matlab. The simulation results show that the solution of forward problem using finite-element method has the features of strong logicality, high accuracy, strong stability and lower complexity. Improved genetic algorithm has better convergence, precise object localization and better imaging effect comparing with LBP and Newton-Raphson Method. Both the theory analysis and the result of simulation show the availability and feasibility in appling finite-element method and improved genetic algorithm to electromagnetic tomography image reconstruction.