Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2009. / Includes bibliographical references (p. 83-86).

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 191-204). Also available on the World Wide Web.

Includes bibliographical references (p. 119-126).

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Choi, Seung-Kyum; Committee Member: Muhanna, Rafi; Committee Member: Rosen, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--Missouri University of Science and Technology, 2009. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 23, 2009) Includes bibliographical references (p. 66-68).

Solar thermal energy harvesting is a promising solution to offset the electricity demands of a growing population. The use of the technology is however still limited and this can most likely be attributed to the capital cost and also the intermittent nature of solar energy which requires incorporation of a storage system. To make the technology more attractive and effective, cheap means of harvesting solar energy and the development of efficient and inexpensive thermal energy storage devices will improve the performance of solar energy systems and the widespread use of solar energy. Heat storage in a packed-bed rock with air as the working fluid presents an attractive and simple solution for storing solar thermal energy and it is recommended for solar air heaters. A packed-bed rock storage system consists of rocks of good heat capacity packed in a storage tank. The working fluid (air) flows through the bed to transfer its energy. The major concern of the design for a packed-bed rock thermal storage system is to maximize the heat transfer and minimise the pressure drop across the storage tank and hence the pumping power. The time duration the stored energy can be preserved and the air flow wall effect through the bed are the common complications encountered in this system. This study presents an experimental and analytical analysis of a vacuum storage tank with the use of expanded perlite for high temperature thermal energy storage in a packed-bed of rocks. Dolerite rocks are used as the storage medium due to their high heat capacity and as they are locally available. To minimise the pressure drop across the tank, moderate rock sizes are used. The tank contains baffles, allowing an even spread of air to rock contact through the entire tank, therefore improving heat transfer. There is a good correlation between the predicted and the actual results (4 percent) which implies that the baffles incorporated inside the vacuum tank forces the air through the entire tank, thereby resulting in an even lateral temperature distribution across the tank. The investigation of heat loss showed that a vacuum with expanded perlite is a viable solution to high temperature heat storage for an extended period. The research also focuses on the investigation of a proposed low cost parabolic trough solar collector for an air heating system as shown in Figure (1.3). The use of a standard solar geyser evacuated tube (@R130 each) has cost benefits over the industry standard solar tubes normally used in concentrating solar power systems. A mathematical was developed to predict the thermal performance of proposed PTC and it was found that the measured results compared well with the predictions. The solar energy conversion efficiency of this collector is up to 70 percent. This research could impact positively on remote rural communities by providing a source of clean energy, especially for off-grid applications for schools, clinics and communication equipment. It could lead to a significant improvement in the cost performance, ease of installation and technical performance of storage systems for solar heating applications.

M.Phil (Engineering Management) / The importance of an effective maintenance programme cannot be over-emphasized because such a programme plays such an important role in the effectiveness of lean manufacturing. Maintenance may be considered the health care of any engineering equipment and its equipment. It is required to reduce waste effectively, and to run an efficient, continuous locomotive operation within a business or service operation. The cost of regular maintenance is very small when it is compared to the cost of a major breakdown at which time production is held up. The main purpose of regular maintenance is to ensure that all equipment required for production is operating at 100% efficiency at all times. Through short daily inspections, cleaning, lubricating, and making of minor adjustments, minor problems can be detected and corrected before they become major problems that can shut down a production line. A good maintenance programme requires company-wide participation and support by everyone from top executives to shop floor personnel (Dale, 2008) The function of reliability engineering is to develop the reliability requirements for a product, establish an adequate reliability programme, and perform appropriate analyses and tasks to ensure that the product meets its requirements. These tasks are managed by a reliability engineer who usually holds an accredited engineering degree and has additional reliability-specific education and training. Reliability engineering is closely associated with maintainability engineering and logistics engineering. Many problems from other fields can also be tackled using reliability engineering techniques (O’Connor 2010). Reliability is defined as the probability that a device will perform its required function under stated conditions for a specific period of time, and quality can be defined as how the recipient of the product or service views the product (Barringer, 2006). Therefore the two cannot be viewed differently as they both have the same focus which is the end result of the product’s performance. The findings reveal that customers should form part of reliability management systems; the development of ways to identify possible failure before it actually happens is key in achieving reliability targets; and training of key personnel on engineering and quality department as well as resource planning and utilization is a key towards eliminating reliability challenges.

This dissertation deals with the important issue of reliability management for 3kV DC Traction Substations. A general introduction explaining the changes that took place in the railway environment is followed by a description of the system. Understanding the components of the system is important but care must be taken not to go into too much detail. The level at which the system is broken down will be sufficient for this study. Some relevant reliability theory is discussed and applied to the 3kV DC system. An analysis of the failure modes and criticality helps to identify the components that need special focus during the inspections. With a good understanding of the above aspects a process for the inspection of substations is formulated. To design a process that can be used throughout an organisation, certain test must be done. The tests include determining the influence of expertise and experience of the person carrying out the inspections. The result of this study is an inspection process for 3kV DC traction substations that can be used to obtain a good idea of the condition of the system in order to make maintenance decisions that will improve the reliability of the system. / Prof. J.H.C. Pretorius Prof. W.A. Cronje

Master of Science

Undependable systems are unable to accomplish the mission for which they were designed and cause tremendous loss [Airwar-Vietnam, 1978]. In most instances, timely maintenance is a vital necessity for a system to be kept in or returned to its operating condition, and to be able to successfully complete a specific mission. In a scarcer-resource but higher-competition environment, it is essential that system dependability be considered as a major system parameter and be evaluated during the early phases of the system design process. Given a specific system mission profile, whether or not the mission can be successfully completed is based not only on such measures as performance, reliability, maintainability, and/or availability. There is a need for system designers and engineers to meeasure system dependability, as well. System dependability is a measure of effectiveness which allows for the consideration of maintenance in the life cycle as long as it does not inhibit the system from fulfilling its mission. It is the aim of this project to develop a methodology for the analysis and evaluation of system effectiveness through the utilization of the system dependability measure. The concept and the mathematical model of system dependability is discussed. Effectiveness factors and relationships are described, a measure of system dependability has been defined, and a computer -based tool was developed to enable the accomplishment of trade-off analyses and the evaluation of various system configurations in terms of dependability. Maintenance requirements are addressed through the introduction of various combinations of failures, and failure distributions include the consideration of the exponential, Weibull, and log-normal cases. Application of the dependability model is illustrated through a case study involving an aircraft radar trated through a case study involving an aircraft radar is illustrated through a case study involving an aircraft radar subsystem as an example. / Master of Science