Search Results

1 - 4 of 4 items

  • Author: J. Nagaraju x
Clear All Modify Search
Electrical Impedance Spectroscopic Studies on Broiler Chicken Tissue Suitable for the Development of Practical Phantoms in Multifrequency EIT

Abstract

Phantoms are essential for assessing the system performance in Electrical Impedance Tomography (EIT). Saline phantoms with insulator inhomogeneity fail to mimic the physiological structure of real body tissue in several aspects. Saline or any other salt solution is purely resistive and hence studying multifrequency EIT systems cannot be assessed with saline phantoms because the response of the purely resistive materials do not change over frequency. Animal tissues show a variable response over a wide band of signal frequency due to their complex physiological and physiochemical structures and hence they can be suitably used as bathing medium and inhomogeneity in the phantoms of multifrequency EIT systems. An efficient assessment of a multifrequency EIT system with a real tissue phantom needs a prior knowledge of the impedance profile of the bathing medium as well as the inhomogeneity. In this direction Electrical Impedance Spectroscopy (EIS) studies on broiler chicken muscle tissue paste, muscle tissue blocks and fat tissue blocks are conducted over a wide range of signal frequency using impedance analyzers, and their impedance profiles are analyzed. Results show that the chicken muscle tissue paste is less resistive than the fat tissue and hence it can be used successfully as the bathing medium of the phantoms for impedance imaging in multifrequency EIT. Fat tissue is found more resistive than the muscle tissue which makes it more suitable for the inhomogeneity in phantoms of impedance imaging study. Moreover, as there is a large difference between the resistivities of muscle tissue and fat tissue they can be used as either inhomogeneity or background medium. EIS studies also show that the variations in the impedance parameters of a muscle tissue block are greater than in the tissue paste as the cell membrane structures are destroyed in tissue paste. Results also show that the α and β dispersions are visible in all the parameters of both the tissue samples, but both the dispersions are larger in the muscle tissue block. The Nyquist plot obtained for the muscle tissue block demonstrates that the equivalent electric model of the tissue sample contains Warburg impedance and a constant phase element.

Open access
Improving Conductivity Image Quality Using Block Matrix-based Multiple Regularization (BMMR) Technique in EIT: A Simulation Study

Abstract

A Block Matrix based Multiple Regularization (BMMR) technique is proposed for improving conductivity image quality in Electrical Impedance Tomography (EIT). The response matrix (JTJ) has been partitioned into several sub-block matrices and the largest element of each sub-block matrix has been chosen as regularization parameter for the nodes contained by that sub-block. Simulated boundary data are generated for circular domains with circular inhomogeneities of different geometry and the conductivity images are reconstructed in a Model Based Iterative Image Reconstruction (MoBIIR) algorithm. Conductivity images are reconstructed with BMMR technique and the results are compared with the Single-step Tikhonov Regularization (STR) and modified Levenberg-Marquardt Regularization (LMR) methods. Results show that the BMMR technique improves the impedance image and its spatial resolution for single and multiple inhomogeneity phantoms of different geometries. It is observed that the BMMR technique reduces the projection error as well as the solution error and improves the conductivity reconstruction in EIT. Results also show that the BMMR method improves the image contrast and inhomogeneity conductivity profile by reducing background noise for all the phantom configurations.

Open access
Improving Image Quality in Electrical Impedance Tomography (EIT) Using Projection Error Propagation-Based Regularization (PEPR) Technique: A Simulation Study

Abstract

A Projection Error Propagation-based Regularization (PEPR) method is proposed and the reconstructed image quality is improved in Electrical Impedance Tomography (EIT). A projection error is produced due to the misfit of the calculated and measured data in the reconstruction process. The variation of the projection error is integrated with response matrix in each iteration and the reconstruction is carried out in EIDORS. The PEPR method is studied with the simulated boundary data for different inhomogeneity geometries. Simulated results demonstrate that the PEPR technique improves image reconstruction precision in EIDORS and hence it can be successfully implemented to increase the reconstruction accuracy in EIT.

Open access
MHD flow of longitudinal and torsional oscillations of a circular cylinder with suction in a couple stress fluid

Abstract

In this paper, we consider the flow an incompressible electrically conducting couple stress fluid generated by performing longitudinal and torsional oscillations of a porous circular cylinder subjected to constant suction/injection at the surface of the cylinder and in the presence of a radial magnetic field. A finite difference method is proposed to analyze the velocity components, in an infinite expansion of a couple stress fluid under vanishing couple stresses on the boundary. The effects of the magnetic parameter, couple stress parameter, Reynolds number, the ratio of couple stress viscosities parameter and suction parameter on velocity components and drag are discussed and shown graphically.

Open access