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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The main objective of this study is to develop a new type of machine-component monitoring system which is non-intrusive and non-contact in nature. Moreover, the design of the system to be developed must be robust enough for it to be implemented in an industrial environment. Therefore, this study was initiated to overcome some of the problems that were encountered using the well-established vibration method. For instance, vibration measurement of a machine component is dependent on the quality of contact between an accelerometer with a vibrating surface. Vibration measurement of a machine component is also affected by the vibration of other machine components near the vicinity, in addition to the presence of power-supply-line frequency and its harmonics. On the other hand, the application of a desirable non-intrusive and a non-contact nature of sound pressure measurement method is difficult to carry out if the background sound level is high. This is because sound pressure measurement is dependent on the characteristics of a sound field where a measurement is carried out. For these reasons, air-particle acceleration signals were utilised in the study. Air-particle acceleration is a vector quantity and measurement of vector property can improve the signal-to-noise ratio of the measured signal, even in a noisy environment. A dedicated test rig was constructed to carry out the experiments and to test the hypothesis. Rolling element bearings were used for the experiment because of the many different types of defect that can develop in them, such as inner race, rolling element and outer race defects. Moreover, the dynamic behaviour of bearings are well understood and can be compared with experimental results obtained from the study. Several different methods of analysis were used in the study including statistical, spectral, cepstral and wavelet transform methods. The results from using air-particle acceleration signals were compared with results obtained from utilising sound pressure and vibration signals. These results showed that the performance from using air-particle acceleration signals were superior to the performance from using sound pressure signals. Results from the analysis of air-particle acceleration signals can clearly indicate the presence of a defective component in the test-bearing. This is so even when the overall background noise was 14dB higher than the overall noise level emitted by the test-bearing. Moreover, the sensitivity of the measurement of air-particle acceleration signal to indicate the presence of a defective bearing was similar to the sensitivity when using conventional vibration equipment. Applications of artificial neural networks were also included for automatic identification of defect signals. The multilayer perceptron network was chosen and tested to classify the bearing signals because of the suitability of this type of network to be used for pattern recognition. Finally, a new type of machine-component monitoring system using air-particle acceleration signal was successfully developed and tested in industry.

Over the last two decades research has shown that the different forms of trace elements in the environment can cause a variety of health concerns as a result of differences in toxicity. The need to establish efficient, effective and reliable speciation methods has become paramount. A basic aim of this work has been to advance speciation measurement capability for key trace elements (mercury, lead and chromium) by devising an integrated analytical approach that links the sample collection, sample preservation and laboratory measurements in an unified manner. An introductory chapter first reviews the occurrence of organometallic compounds in the environment and focuses on the identification of the "environmental compartments" where transformations of such species can take place. Speciation studies also assist in understanding the biogeochemical cycling of trace elements. Moreover, a review of the various methodologies used for trace element speciation measurements including hyphenated techniques and/or a variety of chemical/physical pretreatments in combination with flow injection (FI) is discussed. Chapter 2 describes mercury speciation experiments utilising gas chromatography-microwave induced plasma-atomic emission spectrometry (GC-MIP-AES) and FI. The approach was based on the preconcentration of mercury on sulphydryl cotton and after elution from the microcolumn, separation and quantitation of methyl-, ethyl- and inorganic mercury species. Method development experiments were performed using a derivatisation technique which gave low contamination and allowed rapid analysis of samples. The microcolumn technique was transferred to the field and speciation of mercury in surface waters of the Manchester Ship Canal was undertaken and high methylmercury concentrations (0.052-0.182 ug 1 -1, as Hg) were detected. In so doing the new approach offered the preservation of the natural speciation state of the water sample directly at the sampling site and during the interval between collection and analysis. In chapter 3 lead studies are centred on the development of a rapid speciation scheme for neutral and cationic (organic and inorganic) lead species based on activated alumina microcolumn separation in combination with ICP-MS and FI. The approach permitted rapid assessment of the nature of lead contamination in environmental waters. Speciation of lead in surface waters of the Manchester Ship Canal was also undertaken using the field sampling approach in an attempt to confirm a transmethyllation reaction between organolead and inorganic mercury. A further application for microcolumns, in the context of speciation measurement, is their use as external calibrants and certified reference materials (CRMs) and this is discussed in the penultimate chapter. Key elements were mercury and chromium. After immobilisation of mercury species on SCF microcolumns it was found that recoveries for methyl- and inorganic mercury were quantitative over 4 months in contrast to ethylmercury which was 2 months. Similar studies for chromium species indicated ineffective elution and more vigorous conditions (microwave assisted digestion) for the elution step were used. A final chapter reviews progress and recommendations are given concerning future research and application for microcolumn field sampling in combination with instrumental analytical techniques.