Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 181-189). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 114-127).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (M.S. in Operations Research) Naval Postgraduate School, June 1997. / Thesis advisors, Donald P. Gaver, James A. Scaramozzino. Includes bibliographical references (p. 77-79). Also available online.

Thesis (Ph.D.)--York University, 2008. Graduate Programme in Communication and Culture. / Typescript. Includes bibliographical references (leaves 261-277). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR51780

Master-Arbeit Univ. St. Gallen, 2006.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1972. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:28:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-05Bitstream added on 2014-06-13T20:58:36Z : No. of bitstreams: 1 oliveira_rjg_me_guara.pdf: 1311511 bytes, checksum: 7c57fbdb099a4b3d6123bb38b37813e3 (MD5) / Universidade Estadual Paulista (UNESP) / Na indústria moderna o monitoramento da condição de operação de máquinas rotativas é essencial para se determinar o surgimento de falhas em mancais de rolamentos. Este trabalho apresenta uma técnica de análise adotada para a identificação de falhas em mancais de rolamento em seus estágios iniciais, utilizando procedimentos de análise de sinais no domínio do tempo e da freqüência, com especial atenção para a técnica do HFRT (High Frequency Resonance Technique), também conhecida como Técnica do Envelope. Este método de análise de sinais foi escolhido em razão de ser uma ferramenta apropriada para identificar falhas em mancais de rolamentos na sua fase inicial. A teoria das técnicas foi discutida e os passos para a implementação computacional foram apresentados. As rotinas foram implementadas através da linguagem de programação MATLAB e um sinal simulado representativo de um sinal coletado de um mancal de rolamento com defeito pontual na pista externa foi desenvolvido para verificar a eficácia dos métodos implementados. Os experimentos foram desenvolvidos utilizando-se uma bancada de testes aplicada para testar mancais de rolamento com defeitos pontuais produzidos em laboratório. A aquisição dos dados foi desenvolvida com instrumentação comercial. Os resultados obtidos mostraram ser efetivos para identificar falhas em rolamentos para os dados simulados e dados experimentais. / In the modern industries, the condition monitoring of the rotational machinery operation is important to evidence the beginning of the fails in bearings. This work presents a technique of analysis applied to identify fails in bearing during the initial phases, using techniques of signal analysis in time and frequency domain with special attention for the High Frequency Resonance Technique, also called envelope technique. This method for signal analysis was chosen because is an appropriated tool to identify fails in bearings during initial phases. The theory for the techniques was discussed and the steps for the computational implementation were showed. The routines were implemented through MATLAB programming language and it was prepared a representative signal of a bearing with a single point defect in the outer race in order to verify the capability of the method implemented in the routine. The experiments were performed using a experimental test rig applied to test bearings with single point defects performed in laboratory. The data acquisition were performed with commercial instrumentation. The results obtained shown to be effective to identify fails in bearings for both numerically simulated data and experimental data.

Wave energy has the potential to be a major contributor to the global energy mix. It is estimated that commercial deployment of wave and tidal energy arrays could meet as much as 20% of the UK’s current electricity demand, with an installed capacity of 30-50 GW providing up to 16,000 jobs. However, the wave energy sector has not yet developed into a commercial industry due to several key challenges. One reason private investors have been reluctant to back the sector is that the uncertainty surrounding lifetime costs of wave energy arrays makes it difficult to obtain reliable estimates for overall cost of energy. In order to improve these estimates, a better understanding of the operations and maintenance (O&M) phase of wave energy arrays needs to be gained. This thesis presents an O&M simulation tool designed for wave energy arrays. The work presented uses the model to assess aspects of O&M strategies for two different types of wave energy converter. Uncertainty in the model inputs is also addressed by undertaking a series of sensitivity analyses. The methods and results presented in this thesis highlight the importance of using an O&M simulation tool to plan lifetime logistics for wave energy arrays and obtain realistic cost estimates. The work has also shown how an O&M tool can be used to identify critical components in wave energy converters, thereby helping to design the best device possible for the challenging marine environment. Understanding lifetime costs of wave energy arrays will drive the sector towards commercialisation, bringing wave energy a step closer to fulfilling its potential as a major contributor to global energy production.

M.Ing. / Ever since man had invented the wheel, or for that matter any of his first hand tools, he had a definite need to maintain that object. Man did not have any means to predict failures and he had no idea of how to prevent them. He could not plan for these failures and would not know what material and resources to have on hand. He was obviously restricted to a very primitive and elementary form of breakdown maintenance or a sort of run to break strategy as we would call that in modern maintenance terms. His success could only be measured in terms of the time to the next failure. Due to the nonexistence of engineering standards, the large standard deviation in mean time between maintenance (MTBF) values would render these same values rather useless for predictive purposes. This situation restricted our forefathers to a very reactive approach to maintenance. The astonishing present levels of sophistication in man's skills, engineering design and manufacturing came about through revolution and evolution. This indicates a huge amount of change that has taken place over the years and is still taking place today. As the world is in a constant state of change no business organization can escape the effects of operating m a continually evolving landscape. The very forces of change come about typically through industrial globalization, technological advance, political upheaval, the opening up of new markets and the changing expectations of customers that become more knowledgeable and demanding. For any business to respond to customer needs in a satisfactory manner, that business will have to be highly dependent on logistics. As logistics is a major contributor to life cycle cost (Blanchard, 1992: 70-84) and therefor impacts directly on profit margins, there is a growing need for more effective and efficient management of an organization's resources. Logistic support for any organization or plant is a major consideration in the early design stages of any system or organization or plant. From a logistic support perspective it becomes therefor necessary to assure the effective and economical support of a system, organization or plant throughout its programmed life cycle. One of the most important logistic support elements is maintenance. A lot has been said and written about maintenance. A number of well known philosophies and procedures (Blanchard, 1992: 9-25) such as 'planned preventive maintenance' (PPM), `condition based monitoring' (CBM), 'reliability centered maintenance' (RCM), 'total productive maintenance' (TPM), 'just in time' (JIT), 'life cycle costing' (LCC), etc. have been developed over many years and are applied throughout the world today. Techniques such as 'failure mode effect and criticality analysis' (FMECA), 'fault diagnostics', 'quality circles', and others have also been introduced to the industry. However various studies (Willmott, 1990: 17) have shown that present levels of maintenance management effectiveness are still unsatisfactory. One of the most important reasons for this state of affairs is that maintenance is still viewed by many organizations as a technical activity rather than an integrated management discipline. This misconception is then reinforced by several factors such as that the maintenance department is at its most visible when an emergency malfunction occurs. As soon as the malfunction has been restored, production carries on with its activities and no one asks the question why the breakdown was not anticipated before it occurred and disrupted production. A second reason is that maintenance managers view themselves as fire fighters and not as managers. A third reason is that the maintenance department is viewed as an organizational function with unpredictable response times and erratic priorities. All of these prejudices and misconceptions are costing industry dearly. This study will indicate that much can be done to transform the maintenance function of any organization to such an extent that costs are minimized and plant availability is improved that will ultimately lead to higher profit margins.