Thesis (M.S.)--Ohio University, June, 2005. / Title from PDF t.p. Includes bibliographical references (p. 86-88)

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007. / Bruce R. Ellingwood, Committee Chair ; Abdul-Hamid Zureick, Committee Member ; James I. Craig, Committee Member ; Reginald DesRoches, Committee Member ; Kenneth M. Will, Committee Member.

M. Phil. / Concrete is worldwide the most commonly used construction material and, although concrete is durable when exposed to aggressive conditions, it requires some maintenance. If this maintenance is neglected for a prolonged period of time, intrinsic and extrinsic factors will cause the concrete to degrade necessitating repair and rehabilitation. The correct diagnosis of the root cause of degradation, proper specification of repair materials and quality execution of the concrete repairs all contribute to the reliability of the repairs. The correct management of the repair process is necessary to ensure reliability in order for the structure to be returned to an acceptable state.

Optical fibre networks play an increasingly prominent role in communications. As networks grow in size and complexity, the probability and impact of failures increase. In this dissertation, different optical network concepts, survivability and resilience methods are considered. Link and Path failures are discussed and Static Path Protection (SPP), Shared Backup Path Protection (SBPP), as well as Path Restoration (PR) are investigated. A Shared Backup Path Protection model and simulation tool is designed and implemented. This implementation is compared with other studies. Dual-link failures are considered under specific network topologies. Shortest Path algorithms are used to reprovision optimal routes for backup protection. Results and conclusions are discussed in detail, giving valuable insight into resilience methods. Availability and protectability are discussed and evaluated as measures of resilience and network survivability. Results vary between compromising little availability and bringing a significant improvement in availability. It is concluded that the implementation of SBPP is a necessity in highly-meshed networks with high availability needs, but doesn’t necessarily provide the best solution for sparsely-connected networks. The additional cost involved in the implementation needs to be considered carefully. / Dissertation (MEng)--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted

Maintenance models are critical for evaluation of the alternative maintenance policies for modern engineering systems. A poorly selected policy can result in excessive life-cycle costs as well as unnecessary risks for catastrophic failures of the system. Economic dependence refers to the difference between the cost of combining the maintenance of a number of components and the cost of performing the same maintenance actions individually. Maintenance that takes advantage of this difference is often called opportunistic. Large number of components and economic inter-dependence are two pervasive characteristics of modern engineering systems that make the modeling of their maintenance processes particularly challenging. Simulation is able to handle both of these characteristics computationally, but the complexity, especially from the model verification perspective, becomes overwhelming as the number of components increases. This research introduces a new procedure for maintenance models of multi-unit repairable systems with economic dependence among its components and under opportunistic maintenance policies. The procedure is based on the stochastic Petri net with aging tokens modeling framework and it makes use of a component-level model approach to overcome the state explosion of the model combined with a novel order-reduction scheme that effectively combines the impact of other components into a single distribution. The justification for the used scheme is provided, the accuracy is assessed, and applications for the systems of realistic complexity are considered.

Companies have invested large amounts of money on information systems development. Unfortunately, not all information systems developments are successful. Software project failure is frequent and lamentable. Surveys and statistical analysis results underscore the severity and scope of software project failure. Limited research relates software structure to information systems failures. Systematic study of failure provides insights into the causes of IS failure. More importantly, it contributes to better monitoring and control of projects and enhancing the likelihood of the success of management information systems. The underlining theories and literature that contribute to the construction of theoretical framework come from general systems theory, complexity theory, and failure studies. One hundred COBOL programs from a single company are used in the analysis. The program log clearly documents the date, time, and the reasons for changes to the programs. In this study the relationships among the variables of business requirements change, software complexity, program size and the error rate in each phase of software development life cycle are tested. Interpretations of the hypotheses testing are provided as well. The data shows that analysis error and design error occur more often than programming error. Measurement criteria need to be developed at each stage of the software development cycle, especially in the early stage. The quality and reliability of software can be improved continuously. The findings from this study suggest that it is imperative to develop an adaptive system that can cope with the changes to the business environment. Further, management needs to focus on processes that improve the quality of the system design stage.

M.Phil. / “Failure is one of the unfortunate facts of life”. This is the very first statement in the book by Coetzee (1998). This statement is unfortunately true, leading to the fact that failure is a reality, to be dealt with. Dealing with it in a proactive way will provide warnings of an approaching failure. Dealing with it in a reactive way will go through the “surprising pain” of an unexpected breakdown or downtime. In both cases the source of failure must be known to prevent it from happening again. Root Cause Analysis (RCA) is a structured method of determining the reason (root cause) of a failure. On the other hand, Vibration Analysis is one of the best known methods of condition monitoring and has the capability to indicate a reason for failure, although not necessarily the root cause or causes. The objective of this dissertation is to investigate the possibility to combine the RCA method with Vibration Analysis as forensic science to improve the success of finding root causes and their solutions.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982. / Includes bibliographical references. / by Xi-Cheng Lou. / M.S.

Preventing bad things from happening to engineered systems, demands improvements to how we model their operation with regard to safety. Safety-critical and fiscally-critical systems both demand automated and exhaustive verification, which is only possible if the models of these systems, along with the number of scenarios spawned from these models, are tractably finite. To this end, this dissertation ad dresses problems of a model's tractability and usefulness. It addresses the state space minimization problem by initially considering tradeoffs between state space size and level of detail or fidelity. It then considers the problem of human interpretation in model capture from system artifacts, by seeking to automate model capture. It introduces human control over level of detail and hence state space size during model capture. Rendering that model in a manner that can guide human decision making is also addressed, as is an automated assessment of system timeliness. Finally, it addresses state compression and abstraction using logical fault models like fault trees, which enable exhaustive verification of larger systems by subsequent use of transition fault models like Petri nets, timed automata, and process algebraic expressions. To illustrate these ideas, this dissertation considers two very different applications - web service compositions and submerged ocean machinery. / by John C. Sloan. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Abstract not available