Wind is becoming an increasingly important source of energy for countries that ratify to reduce the emission of greenhouse gases and mitigate the effects of global warming. Investments in wind farms are affected by inter-related assets and stakeholders’ requirements. These requirements demand a well-founded Asset Management (AM) frame-work which is currently lacking in the wind industry. Drawing from processes, tools and techniques of AM in other industries, a structured model for AM in the wind industry is developed. The model divulges that maintenance is indispensable to the core business objectives of the wind industry. However, the common maintenance strategies applied to wind turbines are inadequate to support the current commercial drivers of the wind industry. Consequently, a hybrid approach to the selection of a suitable maintenance strategy is developed. The approach is used in a case study to demonstrate its practical application. Suitable Condition-Based Maintenance activities for wind turbines are determined. Maintenance optimisation is a means to determine the most cost-effective maintenance strategy. Field failure and maintenance data of wind turbines are collected and analysed using two quantitative maintenance optimisation techniques; Modelling System Failures (MSF) and Delay-Time Maintenance Model (DTMM). The MSF permits the evaluation of life-data samples and enables the design and simulation of a system’s model to determine optimum maintenance activities. Maximum Likelihood Estimation is used to estimate the shape (β) and scale (η) parameters of the Weibull distribution for critical components and subsystems of the wind turbines. Reliability Block Diagrams are designed using the estimated β and η to model the failures of the wind turbines and of a selected wind farm. The models are simulated to assess and optimise the reliability, availability and maintainability of the wind turbine and the farm. The DTMM examines equipment failure patterns by taking into account failure consequences, inspection time and cost in order to determine optimum inspection intervals. Defects rate (α) and mean delay-time (1/γ) of components and subsystems within the wind turbine are estimated. Optimal inspection intervals for critical subsystems of the wind turbine are then determined.

Företaget Xylem Flygt i Emmaboda producerar dränkbara pumpar av olika storlek och typer som används i hela världen. Innan pumparna levereras till kund testas de i Xylem’s egna testanläggningar. Anläggningen Q2 som berörs i rapporten består av en bassäng med tillhörande rörsystem, ventiler, anslutningsutrustning och mätutrustning. Denna rapport undersöker och lägger fram förslag på förbättringsmöjligheter rörande testanläggningens underhållsplanering. Frågor som undersöks är, om anläggningen ser kvalitetsmässigt och utseendemässigt riktigt ut inför kundbesök, tidsintervaller mellan förebyggande underhåll, miljöansvar angående vattenbyte i bassäng, möjlighet att implementera resultatet på övriga anläggningar samt rekommendationer på uppföljning. Rapporten resulterade i checklistor till underhållsavdelning och operatörer av anläggningen, dokumentation av komponenter och förbättringsförslag. / The company Xylem Flygt in Emmaboda produces submersible pumps of various sizes and types used worldwide. Before the pumps are delivered to the customer they are tested in Xylem's own testing facilities. The plant Q2 concerned in the report consists of a basin with associated piping, valves, connection equipment and measurement equipment. This reports main objective is to investigate and make proposals for improvement regarding test facility maintenance planning. Other questions examined areIf the plants looks representable in quality and appearance to the visiting customers, the time intervals between preventive maintenance, environmental responsibility regarding the change of water in the basin, the ability to implement the results in other facilities as well as recommendations on follow-up’s. The report resulted in checklists for the maintenance department and the operators of the facility, documentation of components and improvement proposals.

Ces dernières décennies ont vu une évolution remarquable du contexte économique des entreprises. Ceci est dû certainement à la compétition fortement croissante à laquelle elles sont confrontées. Cette forte concurrence a entraîné les entreprises à investiguer des voies pour améliorer leurs performances économiques tout en répondant aux mieux aux exigences de leurs clients. La clé de la réussite de la majorité des entreprises réside dans la mise en place d’une méthode de gestion économique des différentes fonctions. Les industriels et les chercheurs ont prouvé l’existence d’une forte interaction entre trois fonctions fondamentales de l’entreprise ; la maintenance, la production et la qualité. Ils ont démontrés qu’une gestion indépendante de ces trois fonctions n’est plus efficiente. Suite à ce constat, nous nous sommes intéressés dans ce projet de recherche au développement de nouvelles stratégies de maintenance intégrée à la production et à la qualité. En tenant compte du prix de vente, des coûts de retouche, de la maintenance et ceux de la production, une analyse de l’interdépendance des trois fonctions a permis de réaliser notre objectif qui consiste à maximiser les profits des entreprises. Le but de cette thèse consiste, à proposer des nouvelles approches de maintenance intégrée à la qualité en tenant compte de la dégradation progressive du système de production, son impact sur la qualité des produits finis et l’impact économique des actions de retouche. Des modèles analytiques ont été développés afin d’illustrer les stratégies proposées. L’effet de la dégradation du système de production sur la perte de qualité du produit fini et son impact économique ont été mis en équation par le biais de modèles mathématiques. Dans ce contexte, différentes politiques de maintenance (parfaite, imparfaite, semi parfaite) ont été traitées. L’existence des solutions optimales liées aux variables de décision a été démontrée analytiquement. Enfin, des résolutions numériques, basées sur des cas industriels, ont été présentées afin de valider les résultats théoriques obtenus. La robustesse des modèles analytiques développés a été prouvée par des études de sensibilité / The last few decades have been marked by a remarkable change in the economic environment of companies. It is due certainly to the increasing competition that they face. This strong competition has led companies to investigate new ways to improve their economic performance while meeting their customers' requirements. The key to the success of the majority of companies lies in the implementation of an economic management method of various functions. Industry and researchers have demonstrated a strong interaction between the three fundamental functions of the company; maintenance, production and quality. They have demonstrated that an independent management of these three functions is no more efficient. Following this observation, we were interested in this research project in the development of new maintenance strategies integrated production and quality. Taking into account sales prices, reworking costs, maintenance costs and production costs, an analysis of the interdependence of the three functions enabled us to achieve our goal of maximizing the profits of companies. The purpose of this thesis is to propose new approaches integrated quality and maintenance taking into account the progressive degradation of the production system, its impact on the quality of output products and the economic impact of reworking actions. Analytical models have been developed to illustrate the proposed strategies. The effect of the degradation of the production system on the degradation of quality of output products and its economic impact has been modeled using mathematical models. In this context, various maintenance policies (perfect, imperfect, semi-perfect) have been studied. The existence of optimal solutions related to the decision variables has been analytically demonstrated. Finally, numerical resolutions, based on industrial cases, have been presented in order to illustrate the theoretical results obtained. The robustness of the analytical models developed has been proved by sensitivity studies

Handing over a software system from development to maintenance is still an under-researched domain. The software community has a hazy insight into its constellation and inherent activities. In this paper, we have evaluated a preliminary version of a taxonomy of handover activities within one Swedish software company. The evaluation is conducted in an in-house handover context only. Despite this, our results provide evidence of its enormous complexity, variability and strong dependency on many other software engineering processes. / © 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.QC 20120223

No description available.

One of the overarching goals for military aircraft sustainment is to keep a high proportion of aircraft available despite the need for maintenance. Traditional solutions to this problem require conservative resource estimates, but this is costly. In recent years an overall paradigm shift towards affordability has created pressure to find other options for achieving high values of fleet level metrics. Past efforts at increasing affordability have had mixed success, and as a result such strategies need to be tested early on in the lifetime of a product, ideally before the product is ever fielded. In order to provide the ability to evaluate the effects of sustainment decisions such as different maintenance paradigms and cost goals, this thesis develops a sustainment modeling environment, known as Sustain-ME, to facilitate open analysis based on the best information available. The goal of creating Sustain-ME is to allow decision makers to define a sustainment scenario and compare different decisions of interest on a common basis. Sustain-ME is a discrete event simulation, which means it efficiently provides a reasonable prediction of operational behavior. This thesis describes the information used to construct Sutain-ME, including the assumptions made for many of the parameters of the modeled sustainment process. It next verifies the behavior of the different elements that make up the sustainment model including operations, maintenance, maintenance paradigms, and the supply chain. Finally a methodology for using SustainME is defined and a demonstration of the types of studies Sustain-ME was built to perform is shown. The demonstration compares three different maintenance paradigms: reactive maintenance, condition based maintenance, and a novel CBM paradigm known as CBM-MiMOSA.

published_or_final_version / Applied Statistics / Master / Master of Social Sciences

published_or_final_version / Social Work and Social Administration / Master / Master of Social Sciences

No description available.

Thesis (M.H.A.)--University of Michigan, 1978.