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The process of computerised tomography (CT) has been developed for medical imaging purposes using a variety of X-ray scannars. So far, little attention has been paid to industrial applioaticns of this technique, largely because of the constraints of expense. An investigation was made of the suitability of one medical scanner, the EMI CT5005, as an industrial scanning tool. This showed up a variety of problems when scanning non-medical objects, and suggested an alternative approach to the problem. This was to construct an experimental scanner based on gamma-ray sources, to overcome the problems of beam hardening,, and provide versatility and, perhaps, portability. The greatest limitation on this sort of device is the time needed to produce a scan. However, even with small laboratory sources it seemed possible to produce a usable scanner. This experimental scanner was constructed and developed to the stage of producing very acceptable images, albeit of moderate resolution. This thesis outlines the basic theory of reconstructing images using CT, and describes the considerations leading to the development of the experimental scanner. The scanner itself is described, along with details of control, data processing, and the problems encountered. The statistical limitations on the scanner are described, and the way these affect the quality of the final CT image is investigated in detail. A variety of applications of the scanner are suggested, both in its present form and with foreseeable development, and a catalogue of the scans obtained using the scanner is provided.

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The customary procedures of roundness measurement have been developed in response to particular needs as they have arisen, incorporating approximations as appropriate. Consequently, the direct extension of these procedures to more complex measurements such as “cylindricity” is a questionable exercise. The present work develops a mathematically consistent description of the processes underlying the measurement and analysis of roundness. From this are derived analytical methods appropriate to measurements for which instrumentation is, in some cases, yet to become available. New, highly efficient algorithms for solving the minimum circumscribing, maximum inscribing and minimum zone reference figures are also produced. The method adopted identifies important features of roundness measurement such as eccentricity and radius suppression as translations between co-ordinate frames associated with the workpiece and instrument. Reference figure fitting is expressed formally as a problem in optimisation and the standard methods of Operations Research applied to it. All four standard reference circles are re-examined in this way leading to generalisations of measurement conditions and improved solution methods. Earlier advocacy of the limacon as a reference figure is confirmed and extended. The relationship of circular and limacon references is studied and an eccentricity ratio shown to be a suitable control over the approximations used in practice. The use of “limacon cyndroids” seems to provide a working approximation for the measurement of cylindricity. It is recommended that cylindrical reference figures be fitted by standard techniques of linear programming rather than by special algorithm.

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Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.