Research On Magnetic Resonance Electrical Resistance Tomography Technology Based On Pipeline Model

In industrial imaging area,electrical resistance tomography(ERT)has been paid highly attention to because of its speediness,security,and non-invasion.But it has not been practically applied in industry because of its low imaging resolution caused by its imaging principle.In the field of medical imaging,since magnetic resonance electrical impedance tomography(MREIT)has been put forward by Zhang in Toronto in 1992,which is combined by electrical impedance tomography(EIT)and magnetic resonance current density imaging(MRCDI),it is now received extensive attention at home and abroad.Following the pioneering work of MREIT reported in the medical field,and in an effort to improve the image resolution for an industrial two phase flow achieved by the ERT technique,the paper presents a work on MRERT for the first time which is aimed at combining the ERT with the MRI technology in order to gain a high image resolution.In this thesis,several works are discussed as follows.(1)An FEM based MRERT forward solver and a sensitivity based MRERT inverse solver are discussed in the paper.A number of simulations are conducted to compare the results obtained by MRERT with those obtained by ERT.It reveals consistently from the simulation that the MRERT technique can yield a superior performance in image resolution to what can be achieved by the ERT counterpart.Besides MRERT has the potential to measure a true multiphase flow which is unthinkable for an ERT system.(2)A method is put forward in this paper which is using area conversion between the triangular and the quadrilateral mesh to achieve the inter-conversion of physical quantities between the two different grid-partitioned systems of ERT technology and MRI technology when they are combined as MRERT technology.This method can make the simulation of MRERT technology much closer to actual conditions of pipe.It can solve the problem of how to combine the two imaging models,which is a key step in simulation of MRERT technology.(3)Using the conversion between the triangular and the quadrilateral mesh,the two different grid-partitioned systems of ERT technology and MRI technology are combined.The forward problem of MRERT technique is computed to frequency offset which can be actually measured by MRI detection system.The results of simulation studies indicate that the MRERT technique has a superior performance in imaging precision and image resolution than that of the ERT technique.Besides MRERT technique can really achieve multiphase flow imaging.