Use this URL to cite or link to this record in EThOS:
Title: Wideband electrical impedance spectro-tomographic imaging
Author: Nahvi, Manoochehr
ISNI:       0000 0001 3439 0754
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2008
Availability of Full Text:
Access from EThOS:
Access from Institution:
The underlying opportunity for this study is that process materials may show considerable change in their electrical properties in response to an injected signal over a wide frequency range. The use of this concept to demonstrate the construction of tomographic images for a range of frequency bands is described. These can then provide a deeper understanding and interpretation of a process under investigation. The thesis presents an in-depth review of the characteristics of the various wideband signals that could be used for simultaneous spectral measurements. This includes an objective selection process that demonstrates that a Chirp signal form offers key advantages. It then addresses the details of the developed method and algorithms for WElT systems that deploy a Chirp wideband excitation signal and a further aspect of the method, based on the time-frequency analysis, particularly wavelet transform, which is used to reveal spectral data sets. The method has been verified by simulation studies which are described. To provide measurements over a required frequency range a linear chirp is deployed as the excitation signal and corresponding peripheral measurements are synthesised using a 2D model. The measurements are then analysed using a wavelet transform algorithm to reveal spectral datasets which are exemplified in the thesis. The thesis then examines the feasibility of the presented method through various experimental trials; an overview of the implementation of the electronic system is included. This provides a single-channel EIT chirp excitation implementation, in essence simulating a real-time parallel data collection system. through the use of pseudo-static tests on foodstuff materials. The experimental data were then analysed and tomographic images reconstructed using the frequency banded data. These included results illustrate the promise of this composite approach in exploiting sensitivity to variations over a wide frequency range. They indicate that the described method can augment an EIT sensing procedure to support spectroscopic analysis of the process materials.
Supervisor: Hoyle, B. S. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Industrial process tomography, Tomographic sensors, Ultrasonic tomography