EMT Design And Simulation Of Special-shaped Structure

Electromagnetic tomography technology is a new process tomography technology based on the principle of electromagnetic induction.Based on the principle of Radon transform,multi-angle cyclic excitation is performed on the same object,and then the detection information is inverted and imaged by algorithms.Its application fields include the detection of the location of metal foreign objects,the monitoring of the degree of reaction to chemical processes,the detection of geological components,biomedicine,position of steel bars in buildings or bridges and so on.This article starts from three parts: the demand for detecting foreign objects in the soles of civil aviation,the distribution of steel bars in buildings and their condition detection,and the need for underground metal detection.The question of how to perform non-destructive testing on metal foreign objects under non-contact conditions is proposed.Electromagnetic tomography technology provides detection methods for the needs of this type of problem,and can invert the material to be detected to image,making the detection results more intuitive.The sensor is the core part of the EMT system.In this paper,the simulation study of the single sensor coil model is carried out.Whether there is metal or not in the detection area,the size of the coil,the coil turns and the frequency of the excitation signal are determined by detecting the change value of the coil induction signal,and verified by actual engineering application.The simulation results have laid a solid foundation for subsequent simulation research.Then explore the sensor array model suitable for near-space foreign object detection.The traditional circular sensor is suitable for the detection of two-phase flow or multi-phase flow in the pipeline,but the effect of detecting foreign objects in the near space is not clear.Therefore,this paper designs two sensor models based on the traditional circular sensor and the flat-type sensor composed of 3 × 3 arrays specifically for near-space foreign object detection.Based on the center points of the two sensor models,the same area is divided intothe same space,and the forward problem of electromagnetic tomography is solved by the disturbance of the interference rod one by one.To solve the inverse problem,because this paper explores the new application field of EMT,the classical algorithm is used to verify whether the sensor design scheme is feasible.Therefore,the detection data of the five models are imaged by linear back projection algorithm and tikhonov regularization algorithm respectively,and the inversion imaging is evaluated by two methods of image reconstruction quality evaluation,mean square error method and signal to noise ratio method,obtained The integrated flat-panel sensor model is more suitable for the detection of metal foreign objects in the near space.