Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Jacob A. Abraham. Vita. Includes bibliographical references. Also available from UMI.

Thesis (M. Eng.)--Carleton University, 1988. / Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Nur Touba. Vita. Includes bibliographical references.

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.

The first effective demonstration of a telescope using reflecting optics was made by Isaac Newton, and his invention was given widespread publicity by the Royal Society of London in 1672. Newtonts instrument was closely associated with the introduction of his new theory of the nature of white light and colour, and for Newton his telescopes practicability remained important to the acceptance of his optical theory. Newtonts telescope, influenced to some extent by the earlier work of James Gregory, encouraged the Royal Society to promote more ambitious trials, but instruments by Robert Hooke and Christopher Cock, and by Newton himself, achieved only limited success. Renewed interest in the reflector followed its re- emergence in Newtonts Opticks of 1704. John Hadleyes successful revival of Newtones instrument led in turn to the establishment in London of competitive commercial manufacture of reflectors in the early 18th century, and by 1710 the market was dominated by the instruments of James Short. Contemporary references to the reflecting telescopes of Newton and others have been analysed to allow the historical development of this work to be established more reliably, and to propose a relationship between the various instruments that may be ascribed to Newton. The emphasis has therefore been placed on the instrumentation itself, on practical detail, and on questions of provenance.

The phenomenon of thermoluminescence (TL) cannot yet be said to be completely understood, and cases of anomalous results from TL dating programmes are not infrequent, although explanations are rarely given. It is therefore useful to put TL dating into a firmer physical framework in which all relevant phenomena can be adequately described, whence the best action can be taken to avoid spurious results. However, TL dating embraces many varied aspects of physics, and a solution to all the problems is not a simple task. This thesis is intended to be an experimental study of some of the main physical techniques in thermoluminescence dating. Following a brief review of the whole field, selected areas presented here have been investigated in more detail. A new TL reader has been implemented with novel design features, including microprocessor controlled heating cycles, a switch-mode power supply direct current heating, all based on a modular concept to facilitate future improvements in the hardware. The use of a microprocessor as the heating controller should enable further development (eg. data collection and processing) to be a straightforward task. Non-linear heating profiles can be generated for glow curve analysis and for providing pre-heat zones. The radioisotope content of ceramics and soils is important in TL dating, and a comparison of commonly used radio assay techniques has been made with the aim of assigning a minimum detectable activity to each technique for a given required accuracy. The analytical methods have been applied to various ceramic samples, and the derived dose rates within the shards are calculated and presented for comparison. Some theoretical aspects of TL described in this thesis include a computer model to simulate common TL phenomena, which is used to investigate the effects of varying the model parameters. A complete solution of the equations determining glow curve shapes produced by hyperbolic heating profiles is presented, with techniques for extracting the mathematical constants describing the model, from them. A brief intercomparison of five quartz samples of differing origins is presented with a trace element analysis of the samples to determine whether there exists a correlation between trace element concentration and the magnitude of the TL properties.

No description available.

No description available.