This thesis describes an investigation into the use of dual modality tomography to monitor multi-component flows. The concept of combining two modalities for this purpose evolved from a desire by the Water Research Council to determine volume flow rates of the major components of sewage. No single sensing method is capable of detecting all suspended solids in sewage flows therefore a decision was taken to combine the technologies of electrical resistance and optical tomography to produce a single measurement system. Sensors for both were positioned around the periphery of a static, circular phantom to allow comparisons between dual and single modalities. Modelling was carried out to determine the behaviour of the electrical impedance and optical tomography technologies in a three dimensional situation, where a variety of flow components exist. This provided a greater understanding of the problems involved in combining these technologies and an appreciation of the potential benefits. The remainder of the work can be divided into three areas. Firstly, hardware was constructed to make voltage measurements for both modalities. Secondly, software was written to perform data acquisition, data manipulation and image reconstruction using a simple back projection algorithm developed for this purpose. Finally, an integration of the individual hardware and software components was performed to produce a dual modality system on which tests were carried out to determine the resulting benefits over single modality alternatives.

Made available in DSpace on 2014-10-09T12:34:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:10Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:10/03123-8

Made available in DSpace on 2014-10-09T12:34:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:10Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A detecção de lesões cariosas nos estágios iniciais possibilita a escolha de tratamentos baseados na preservação da estrutura dental. Dessa forma, a utilização de exames capazes de diagnosticar precocemente essas lesões, como a Tomografia por Coerência Óptica (OCT Optical Coherence Tomography) é adequada. Assim, o objetivo do trabalho foi avaliar a capacidade da OCT em quantificar os estágios de desmineralização do esmalte durante o desenvolvimento de lesões simuladas de cárie, tendo como padrão de referência o teste de microdureza seccional. Foram utilizados 53 dentes terceiros molares hígidos, os quais tiveram as coroas seccionadas para obtenção de 210 amostras. Para avaliar as possíveis alterações sofridas por cada amostra, essas foram examinadas através da técnica de OCT no início do experimento e novamente examinadas após o término do período de ciclagem estabelecido para cada grupo, utilizando os coeficientes de atenuação óptica total e o cálculo de área em gráficos de intensidade de sinal de OCT, como parâmetros de análise. Posteriormente, as amostras foram submetidas a testes de microdureza seccional. A diferença entre os coeficientes de atenuação óptica obtidos antes e depois da ciclagem de pH apresentou elevado grau de correlação com os resultados de microdureza seccional. Por meio da análise das áreas provenientes de gráficos de intensidade de sinal de OCT e microdureza Knoop, ambos em função da profundidade, foi observada relação de linearidade entre os resultados e elevada correlação entre as técnicas avaliadas (ρ = 0,99). De acordo com os resultados, a técnica de OCT foi capaz de detectar diferentes graus de desmineralização do esmalte dental humano em lesões simuladas de cárie. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:10/03123-8

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published_or_final_version / abstract / Anatomy / Doctoral / Doctor of Philosophy

Thesis (Ph.D.)--Tufts University, 2000. / Adviser: David A. Boas. Submitted to the Dept. of Electrical Engineering and Computer Science. Includes bibliographical references (leaves 139-147). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph.D.)--University of Western Australia, 2007.

Thesis (Ph. D.)--Northeastern University, 2008. / Title from title page (viewed May 26, 2009). Graduate School of Engineering, Dept. of Electrical and Computer Engineering. Includes bibliographical references (p. 142-155).

Thesis (Ph. D.)--University of Oregon, 1999. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 197-201). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9948024.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 100-104). Also available on the Internet.