by Ye Jian. / Abstract in English and Chinese. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves [140-147]). / ABSTRACT --- p.i / ACKNOWLEDGEMENTS --- p.v / LIST OF ABBREVIATIONS --- p.vi / TABLE OF CONTENTS / Chapter CHAPTER 1 --- Introduction / Chapter 1.1 --- What is the EBI technique --- p.1-1 / Chapter 1.2 --- Applications of the EBI technique --- p.1-2 / Chapter 1.3 --- The electrical impedance rheopneumography-an overview --- p.1-4 / Chapter 1.4 --- Goal of the work --- p.1-6 / Chapter 1.5 --- Main contributions of the work --- p.1-9 / Chapter 1.6 --- Organization of the thesis --- p.1-9 / Chapter CHAPTER 2 --- Principles of the EBI technique and physiological background of the rheopneumogram / Chapter 2.1 --- Tissue impedance and origins of impedance change --- p.2-1 / Chapter 2.1.1 --- Impedance of living organs --- p.2-1 / Chapter 2.1.2 --- Origins of impedance change --- p.2-2 / Chapter 2.2 --- The data acquisition system (DAS) --- p.2-3 / Chapter 2.2.1 --- Impedance detector --- p.2-3 / Chapter 2.2.2 --- Constant current source and safety consideration --- p.2-4 / Chapter 2.2.3 --- Computer interface --- p.2-5 / Chapter 2.3 --- Electrode systems --- p.2-6 / Chapter 2.3.1 --- Two-/four-electrode systems --- p.2-6 / Chapter 2.3.2 --- Geselowitz lead field theory --- p.2-6 / Chapter 2.3.3 --- Comparisons between the two-/four-electrode systems --- p.2-7 / Chapter 2.4 --- The human cardiovascular system --- p.2-8 / Chapter 2.4.1 --- System operation --- p.2-8 / Chapter 2.4.2 --- Pulmonary hemodynamics --- p.2-9 / Chapter 2.5 --- Physiological background of EIR waveform --- p.2-12 / Chapter 2.6 --- EIR wave morphology and pathological factors --- p.2-13 / Chapter 2.6.1 --- Variations in the a-wave --- p.2-13 / Chapter 2.6.2 --- Variations in the Z-wave --- p.2-14 / Chapter 2.6.3 --- Variations in the C-wave --- p.2-14 / Chapter CHAPTER 3 --- THE COMPOSITION OF IMPEDANCE SIGNAL / Chapter 3.1 --- Introduction --- p.3-1 / Chapter 3.1.1 --- Origins of the TIS --- p.3-1 / Chapter 3.1.2 --- EIR measurement and electrode position --- p.3-2 / Chapter 3.1.3 --- Optimal EIR measurement --- p.3-3 / Chapter 3.2 --- Current path in an inhomogeneous medium --- p.3-4 / Chapter 3.3 --- Numerical model --- p.3-5 / Chapter 3.3.1 --- 2D Model --- p.3-5 / Chapter 3.3.2 --- Tissue resistivity --- p.3-6 / Chapter 3.4 --- Calculation of the potential distribution --- p.3-7 / Chapter 3.5 --- Results --- p.3-9 / Chapter 3.5.1 --- Computer simulations --- p.3-9 / Chapter 3.5.2 --- Experimental results --- p.3-13 / Chapter 3.6 --- Discussions --- p.3-14 / Chapter 3.7 --- Conclusion --- p.3-16 / Chapter 3.8 --- Note on publications --- p.3-17 / Chapter CHAPTER 4 --- ON-LINE RESPIRATORY ARTEFACT REMOVAL VIA ADAPTIVE TECHNIQUE / Chapter 4.1 --- Introduction --- p.4-1 / Chapter 4.2 --- Analysis of the TIS --- p.4-3 / Chapter 4.3 --- Modified adaptive noise canceller --- p.4-7 / Chapter 4.3.1 --- Principle of the ANC method --- p.4-8 / Chapter 4.3.2 --- LMS algorithm --- p.4-8 / Chapter 4.3.3 --- MANC method --- p.4-9 / Chapter 4.3.4 --- Results --- p.4-10 / Chapter 4.4 --- Adaptive moving averager --- p.4-15 / Chapter 4.4.1 --- Modified moving averager --- p.4-15 / Chapter 4.4.2 --- Respiratory artefact elimination with adaptive MMA --- p.4-16 / Chapter 4.4.3 --- Performance of the adaptive MMA filter --- p.4-16 / Chapter 4.4.4 --- Results --- p.4-18 / Chapter 4.5 --- Adaptive FIR filter Design --- p.4-22 / Chapter 4.5.1 --- Introduction --- p.4-22 / Chapter 4.5.2 --- Adaptive FIR filter --- p.4-23 / Chapter 4.5.3 --- Results and discussions --- p.4-24 / Chapter 4.6 --- Simultaneously monitoring respiratory and pulmonary circulation- An application of TIS --- p.4-30 / Chapter 4.7 --- Comparisons of the proposed filter schemes --- p.4-33 / Chapter 4.7.1 --- Performance of the filters --- p.4-33 / Chapter 4.7.2 --- Computational complexity and reduced schemes --- p.4-34 / Chapter 4.8 --- Conclusions --- p.4-37 / Chapter 4.9 --- Notes on publications --- p.4-37 / Chapter CHAPTER 5 --- MODELING ANALYSIS OF THE RHEOPNEUMOGRAM / Chapter 5.1 --- Introduction --- p.5-1 / Chapter 5.2 --- Pulmonary circulation modeling --- p.5-2 / Chapter 5.3 --- Model deduction --- p.5-4 / Chapter 5.3.1 --- Pressure-flow in arteries and veins --- p.5-4 / Chapter 5.3.2 --- The two-chamber model and the EIR model --- p.5-5 / Chapter 5.4 --- Parameter estimation --- p.5-8 / Chapter 5.4.1 --- The fitting function and the parameter equations --- p.5-8 / Chapter 5.4.2 --- Curve fitting --- p.5-10 / Chapter 5.4.3 --- Solution of the parameter equations --- p.5-11 / Chapter 5.5 --- Study of the model parameter sensitivity --- p.5-12 / Chapter 5.6 --- Results --- p.5-13 / Chapter 5.7 --- Conclusion --- p.5-17 / Chapter 5.8 --- Notes on publications --- p.5-17 / Chapter CHAPTER 6 --- ANIMAL EXPERIMENTS AND CLINICAL OBSERVATIONS / Chapter 6.1 --- Introduction --- p.6-1 / Chapter 6.2 --- Animal experiments --- p.6-2 / Chapter 6.2.1 --- Methods --- p.6-2 / Chapter 6.2.2 --- Occlusion of the right pulmonary arterial blood flow --- p.6-3 / Chapter 6.2.3 --- Reflection waves in rheopneumogram --- p.6-4 / Chapter 6.3 --- Clinical observations --- p.6-4 / Chapter 6.3.1 --- Mitral valve stenosis --- p.6-5 / Chapter 6.3.2 --- Obstructive emphysema --- p.6-7 / Chapter 6.4 --- Conclusion remarks --- p.6-8 / Chapter 6.5 --- Notes on publications --- p.6-9 / Chapter CHAPTER 7 --- RECAPITULATION AND TOPICS FOR FUTURE INVESTIGATION / Chapter 7.1 --- Recapitulation --- p.7-1 / Chapter 7.2 --- Conclusions --- p.7-3 / Chapter 7.3 --- Topics for future investigation --- p.7-4 / Chapter 7.4 --- Applications of the EIR technique --- p.7-5 / REFERENCES / APPENDICES / Chapter A. --- A circuit diagram of the four-electrode system --- p.A-l / Chapter B. --- NISA/EMAG (A SOFTWARE PACKAGE OF FEM) --- p.A-2 / Chapter C. --- LMS algorithm --- p.A-3 / Chapter D. --- Curve fitting --- p.A-5 / Chapter E. --- List of publications --- p.A-8

by Ling Chao Dong. / Publication date from spine. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves [102]-107). / ABSTRACT --- p.iii / ACKNOWLEDGEMENTS --- p.v / LIST OF ABBREVIATIONS --- p.vi / Chapter CHAPTER 1 --- Introduction / Chapter 1.1 --- Physiological measurement by EBI technique --- p.1 -1 / Chapter 1.2 --- Application of the EBI technique in the human thorax --- p.1 -2 / Chapter 1.3 --- Development in EIR measurement-An overview --- p.1 -4 / Chapter 1.4 --- Project objective --- p.1-7 / Chapter 1.5 --- Problems to be solved for EBI data acquisition system --- p.1-8 / Chapter 1.6 --- Main contribution of this project --- p.1 -8 / Chapter 1.7 --- Thesis outline --- p.1-9 / Chapter CHAPTER 2 --- Principles of The EBI Technique for Cardiopulmonary System / Chapter 2.1 --- The data acquisition system (DAS) --- p.2-1 / Chapter 2.1.1 --- Impedance measurement --- p.2-1 / Chapter 2.1.2 --- Data extraction and collection --- p.2-3 / Chapter 2.2 --- Constant current source --- p.2-3 / Chapter 2.3 --- Single-source multi-channel EBI controller --- p.2-5 / Chapter 2.4 --- Computer interface --- p.2-6 / Chapter 2.5 --- Tissue impedance and impedance change --- p.2-7 / Chapter 2.5.1 --- Impedance of living tissue --- p.2-7 / Chapter 2.5.2 --- Origins of impedance change --- p.2-8 / Chapter 2.6 --- Cardiovascular physiology in human body --- p.2-10 / Chapter 2.6.1 --- Structure and function of the circulatory system --- p.2-10 / Chapter 2.6.2 --- Principles of hemodynamics in pulmonary circulation --- p.2-12 / Chapter 2.7 --- Clinical application of the EIR waveform --- p.2-15 / Chapter 2.7.1 --- Physiological basis --- p.2-15 / Chapter 2.7.2 --- Clinical application --- p.2-16 / Chapter CHAPTER 3 --- The Composition of EIR Signal / Chapter 3.1 --- Introduction --- p.3-1 / Chapter 3.1.1 --- The impedance change in the transthoracic section --- p.3-1 / Chapter 3.1.2 --- Origins of impedance change in pulmonary circulation --- p.3-2 / Chapter 3.2 --- Examination of contribution of impedance sources via electrolytic tank model --- p.3-3 / Chapter 3.2.1 --- Electrolytic tank set-up --- p.3-3 / Chapter 3.2.2 --- Electrolytic tank procedure --- p.3-4 / Chapter 3.2.3 --- Experimental results and discussion --- p.3-5 / Chapter 3.3 --- The interference behaviour via computer simulation --- p.3-8 / Chapter 3.3.1 --- 2D numerical model --- p.3-9 / Chapter 3.3.2 --- Computer simulation --- p.3-10 / Chapter 3.3.3 --- Results and discussion --- p.3-11 / Chapter 3.4 --- The variation of EIR waveform with electrode size --- p.3-12 / Chapter 3.4.1 --- An electronic model --- p.3-12 / Chapter 3.4.2 --- A simulated source of impedance change in pulmonary circuit --- p.3-16 / Chapter 3.4.3 --- Variation of EIR waveform via computer simulation --- p.3-18 / Chapter 3.4.4 --- Computer simulation results and discussion --- p.3-20 / Chapter 3.5 --- Discussions --- p.3-20 / Chapter 3.6 --- Conclusion --- p.3-21 / Chapter CHAPTER 4 --- A Guard Electrode System to Improve the EIR Measurement / Chapter 4.1 --- Introduction --- p.4-1 / Chapter 4.2 --- Normal electrode system --- p.4-2 / Chapter 4.2.1 --- Normal electrode configuration --- p.4-2 / Chapter 4.2.2 --- Current-guarding technique for the constant-voltage system --- p.4-2 / Chapter 4.3 --- Electric field guarding --- p.4-3 / Chapter 4.4 --- Methods of study --- p.4-4 / Chapter 4.5 --- Results --- p.4-5 / Chapter 4.4.1 --- The change of electric field distribution with guarding --- p.4-5 / Chapter 4.4.2 --- Result from electrolytic tank simulation --- p.4-5 / Chapter 4.4.3 --- Variation of EIR waveform with/without guarding in human thorax --- p.4-6 / Chapter 4.5 --- Discussions and conclusion --- p.4-6 / Chapter CHAPTER 5 --- Human Measurements / Chapter 5.1 --- Introduction --- p.5-1 / Chapter 5.2 --- Variation of EIR waveform from normal human body --- p.5-2 / Chapter 5.2.1 --- Methods --- p.5_2 / Chapter 5.2.2 --- The variation of EIR waveform with electrode position and size --- p.5-3 / Chapter 5.3 --- Clinical observation --- p.5-4 / Chapter 5.3.1 --- What is PTMV --- p.5-4 / Chapter 5.3.2 --- Observing EIR waveform during the PTMV operation --- p.5-5 / Chapter 5.3.3 --- Results and discussion --- p.5-5 / Chapter 5.4 --- EIR for use in PTMV operation --- p.5-7 / Chapter 5.4.1 --- Conventional diagnostic and monitoring methods for PTMV --- p.5-7 / Chapter 5.4.2 --- The characteristic of EIR waveform with mitral stenosis --- p.5-7 / Chapter 5.4.3 --- Use of EIR as an assessing/monitoring tool for PTMV operation --- p.5-8 / Chapter 5.4.4 --- Methodology in this study --- p.5-8 / Chapter 5.4.5 --- Result and discussion --- p.5-9 / Chapter 5.5 --- Conclusion --- p.5-10 / Chapter CHAPTER 6 --- Recapitulation and Topic for Future Investigation / Chapter 6.1 --- Recapitulation --- p.6-1 / Chapter 6.2 --- Topics for future investigation --- p.6-3 / Chapter 6.2.1 --- Improvement to the DAS --- p.6-3 / Chapter 6.2.1 --- Data analysis for PTMV --- p.6-3 / REFERENCES --- p.R-1 / APPENDICES / Chapter A. --- Circuit diagram of electrical bio-impedance source simulator --- p.A-l / Chapter B. --- Circuit diagram of the electrical bio-impedance detector --- p.A-2 / Chapter C. --- Circuit diagram of multi-channel controller for multi-EBI detection --- p.A-3 / Chapter D. --- List of publications --- p.A-4

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 8 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Thesis--Lund Institute of Technology, 1994.

Thesis--Lund Institute of Technology, 1994.

Zn(_x)Co(_2-x)GeO(_4) materials were prepared and the variation in structure with composition was investigated using XED, SEM and EDX analysis. Limited series of solid solution were identified at both ends of the compositional range. D C electrical measurements were carried out to characterize the variation in the resistivity of the materials with humidity. Resistivities of the order of 10(^8) Ω m were observed in dry conditions, decreasing by 4 to 5 orders of magnitude with increasing humidity. Resistivity was not found to vary greatly with composition. Resistivity was temperature dependent, increasing by 1 to 2 orders of magnitude for a 70 C decrease in temperature. A C impedance measurements were performed to gain an understanding of the mechanism of the humidity dependent conductivity. At low frequencies impedance was found to be independent of frequency and humidity dependent. At high frequencies impedance was found to be inversely proportional to frequency and independent of humidity. The break point frequency was also humidity dependent and an increase in the impedance indicated inductive-type behaviour. Complex plane representation of the impedance gave a distorted semicircle at high frequencies and a low frequency tail. At high humidities the tail appears as a straight line, inclined at approximately 45 . At medium levels of humidity a distinctive loop is apparent at the intersection between the semicircle and the tail, corresponding to the inductive behaviour indicated at the break point frequency. The impedance response was modelled by an equivalent circuit consisting of various ideal and constant phase (dispersive) elements. The proposed mechanism of humidity-dependent conductivity is due to chemisorption and physisorption of water vapour from the atmosphere at the surface of the material, It is suggested that conduction occurs by hopping of protons between cheraisorbed hydroxyl groups at low humidities, by diffusion of H(_3)O(^+) ions between the hydroxyl groups at intermediate humidities and by hopping of protons between physisorbed H(_3)O(^+) ions (Grotthus Chain reaction) at high humidities.

We present a novel two-dimensional (2D) MAET scanner, with a rotating object of interest and two fixed pairs of electrodes. Such an acquisition scheme, with our novel reconstruction techniques, recovers the boundaries of the regions of constant conductivity uniformly well, regardless of their orientation. We also present a general image reconstruction algorithm for the 2D MAET in a circular chamber with point-like electrodes immersed into the saline surrounding the object. An alternative linearized reconstruction procedure is developed, suitable for recovering the material interfaces (boundaries) when a non-ideal piezoelectric transducer is used for acoustic excitation. The work of the scanner and the linearized reconstruction algorithm is demonstrated using several phantoms made of high-contrast materials and a biological sample.

This thesis concerns the formation, sintering and humidity dependent electrical behaviour of the spinel ceramic material nickel germanate, Ni(_2)Ge0(_4).Ni(_2)Ge0(_4) has been prepared via the solid state reaction between NiO and GeO(_2) over a range of temperatures, and characterised using a number of techniques. The sintering behaviour of pressed pellets of Ni(_2)Ge0(_4) has also been investigated, together with a characterisation of the microstructure of the sintered bodies. Substitutional doping of Ni(_2)GeO(_4) with Li as a replacement for Ni is found to promote a high degree of shrinkage in the sintering process, probably due to the formation of a liquid phase. XRD revealed that even when 10 % of the Ni atoms were replaced with Li, no change in the crystal structure could be detected. A C. impedance spectroscopy of Ni(_2)Ge0(_4) samples was used to investigate the humidity sensitivity of this material. Equivalent circuit analysis, based on a network of resistors and constant phase elements, shows that the humidity sensitivity is due to conduction in a surface layer of water, in agreement with the models currently popular in the Uterature. Measurement of the water adsorption isotherm of Ni(_2)Ge0(_4) in pellet form indicates that a single monolayer of water is formed at around 20 %R(_H), with an approximately linear increase in water layer thickness up to around 80 %R(_H), after which capillary condensation causes a large increase in the volume of adsorbed water. The information gained on the thickness of this layer of water has been correlated with the resistance of the layer measured by impedance spectroscopy, and subsequently used to provide evidence for a model of the humidity sensitive conduction. The conduction in the surface layer is thought to be due to dissociation of the water, where the amount of dissociation is exponentially dependent on the humidity.

Este trabalho estuda a técnica de reconstrução de imagens conhecido como tomografia por impedância elétrica em um domínio bidimensional. Esta técnica consiste na alocação de eletrodos na fronteira do volume e uma fonte injeta padrões de corrente através dos eletrodos e medem-se as voltagens resultantes na fronteira. Com estes dados estima-se a condutividade (ou resistividade) do interior do domínio criando-se uma imagem do mesmo. A tomografia por impedância elétrica é um problema inverso e mal posto no sentido de Hadamard. Estudam-se diversos métodos de solução para resolver o problema direto usando métodos numéricos como diferenças finitas e volumes finitos. Proporemos os métodos numéricos a serem aplicados na solução do problema direto os quais serão testados com problemas onde a solução analítica é conhecida. Posteriormente aplicaremos os métodos propostos ao problema especifico. Uma questão importante na reconstrução de imagens é propor a maneira como aproximar o Jacobiano (ou matriz de sensibilidade) do problema, assim desenvolvemos uma técnica para a aproximação do mesmo usando os dados fornecidos pelo problema direto. / In this work is studied the technique of reconstruction of images known as electrical impedance tomography for a two-dimensional domain. This technique consists in the allocation of electrodes on the border of the volume and a source injects patterns of current through the electrodes and then measuring voltages through the other electrodes. With these data it is estimated the conductivity (or resistivity) on the interior of the domain and an image is create of it. The electrical impedance tomography is an inverse and ill conditioned problem in the Hadamard sense. In this work, is studying some numerical methods to solve the direct problem and are applied numerical methods such as the finite difference method and the finite volume method. It is proposed some numerical methods to solve the direct problem which will be tested with analytical problems where the solution is known. Later, apply the methods proposed to the specific issue. An important issue in the reconstruction problems is about the Jacobian (or sensitivity matrix) aproximation, thus proposing a technique for the calculation of even using the data provided by the direct problem. Keywords: