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.

No description available.

The move towards integrating products and services has increased significantly. As a result, some business models, such as Product Service Systems (PSS) have been developed. PSS emphasises the sale of use of the product rather than the sale of the product itself. In this case, product ownership lies with the manufacturers/suppliers. Customers will be provided with a capable and available product for their use. In PSS, manufacturers/suppliers are penalised for any down time of their product according to the PSS contract. This has formed a pressure on the service providers (maintenance teams) to assure the availability of their products in use. This pressure increases as the products are scattered in remote places (customer locations). Authors have urged that different product monitoring levels are applied to enable service providers to monitor their products remotely allowing maintenance to be performed accordingly. They claim that by adopting these monitoring levels, the product performance will increase. Their claim is based on reasoning, not on experimental/empirical methods. Therefore, further experimental research is required to observe the effect of such monitoring levels on complex maintenance operations systems as a whole which includes e.g. product location, different types of failure, labour and their skills and locations, travel times, spare part inventory, etc. In the literature, monitoring levels have been classified as Reactive, Diagnostics, and Prognostics. This research aims to better understand and evaluate the complex maintenance operations of a product in use with different levels of product monitoring strategies using a Discrete Event Simulation (DES) approach. A discussion of the suitability of DES over other techniques has been provided. DES has proven its suitability to give a better understanding of the product monitoring levels on the wider maintenance system. The requirements for simulating a complex maintenance operation have been identified and documented. Two approaches are applied to gather these generic requirements. The first is to identify those requirements of modelling complex maintenance operations in a literature review. This is followed by conducting interviews with academics and industrial practitioners to find out more requirements that were not captured in the literature. As a result, a generic conceptual model is assimilated. A simulation module is built through the Witness software package to represent different product monitoring levels (Reactive, Diagnostics, and Prognostics). These modules are then linked with resources (e.g. labour, tools, and spare parts). To ensure the ease of use and rapid build of such a complex maintenance system through these modules, an Excel interface is developed and named as Product Monitoring Levels Simulation (PMLS). The developed PMLS tool needed to be demonstrated and tested for tool validation purposes. Three industrial case studies are presented and different experimentations are carried out to better understand the effect of different product monitoring levels on the complex maintenance operations. Face to face validation with case companies is conducted followed by an expert validation workshop. This work presents a novel Discrete Event Simulation (DES) approach which is developed to support maintenance operations decision makers in selecting the appropriate product monitoring level for their particular operation. This unique approach provides numerical evidence and proved that the higher product monitoring level does not always guarantee higher product availability.

Syftet med denna uppsats är att undersöka vad den horisontella kommunikationen har för roll inom systemförvaltning, och att undersöka vad en effektiv sådan har för påverkan på förvaltningsarbete. Då systemförvaltning är kostsamt är det viktigt för organisationer att det sker effektivt. Effektiviteten i organisationers arbete påverkas av kommunikationen och för att uppnå en effektiv kommunikation krävs en förståelse för horisontell kommunikation. Men inom styrning av systemförvaltning ligger inte fokus på kommunikation. Undersökningen genomfördes med hjälp av kvalitativa semistrukturerade intervjuer. Förvaltningsledningar på en organisation vars förvaltningsarbete styrs av förvaltningsmodellen pm3 studerades. Uppsatsens resultat visar på att en horisontell kommunikation utspelar sig inom förvaltningsarbete, det krävs en kommunikation mellan vissa arbetsroller. Den horisontella kommunikationen har också en betydande roll, då den kan hjälpa till att upprätta enhetliga arbetssätt. Resultatet visar dock att den horisontella kommunikationens funktion inte alltid utnyttjas till fullo. När den inte är effektiv kan det bidra till duplicerat arbete, förlorad och utelämnad information, samt att medarbetares kunskap förbises. Allt detta påverkar i slutändan arbetets produktivitet. Uppsatsens resultat visar att desto effektivare den horisontella kommunikationen är inom förvaltningsarbete, desto effektivare blir arbetet. / The purpose of this thesis is to examine what role lateral communication within the work in software maintenance has, and to examine how an effective lateral communication influences the maintenance work. Software maintenance is costly, therefore it is important for organizations that it is efficient. Organization’s efficiency is influenced by their communication. To attain an effective communication there needs to exist an understanding for lateral communication. Within the guiding of software maintenance there is a lack of regard to the importance of communication. The thesis was conducted using qualitative research. The research is based on semi-structured interviews with solution managers at an organization that has their software maintenance guided by the swedish maintenance management model pm3. The result of this study shows that a lateral communication occurs within the work with software maintenance, communication is required between certain roles. Lateral communication also has a significant role since it can help to uniform the work. However, the results show that the potential of lateral communication is not always used to its full extent. When it is not effective it can result in duplicated work, lost and excluded information, and coworkers’ knowledge can be overlooked. In the end the productivity of the work is affected. The study shows that the more effective the lateral communication is within the work in software maintenance, the more effective the work will become.

published_or_final_version / Real Estate and Construction / Master / Master of Science in Construction Project Management

published_or_final_version / Civil Engineering / Master / Master of Philosophy

<p>Electrical production in Sweden today is mainly from nuclear and hydro power. However, there is large increase in renewable energy like wind power and the installed new capacity goals are large. Several electrical production sources are important for the sustainability of the energy system. Maintenance is an approach for keeping a system sustainable. The importance of structured maintenance for reliable electrical production systems triggers the development of qualitative and quantitative maintenance management methods. Examples of these methods are Reliability-Centered Maintenance (RCM) which is a structured qualitative approach that focuses on reliability when planning maintenance, and Reliability Centered Asset Management (RCAM) which is a development of RCM into a quantitative approach with the aim to relate preventive maintenance to total maintenance cost and system reliability.</p><p>This thesis presents models, as applications of RCAM, based on the methods of Life Cycle Cost (LCC) and mathematical optimization, applied to wind and nuclear power plants. Both deterministic and stochastic approaches have been used and the proposed models are based on the <em>Total Cost</em> model, which summarizes costs for maintenance and production loss, and the <em>Aircraft </em>model, which is an opportunistic maintenance optimization model. Opportunistic maintenance is preventive maintenance performed at opportunities. The wind power applications in this study show on different ways to cover costs of condition monitoring systems (CMS) and further on economic benefits of these when uncertainties of times to failure are included in the model. The nuclear power applications show on that the optimization model is dependent on the discount rate and that a high discount rate gives more motivation for opportunistic replacements. When put into a stochastic framework and compared to other maintenance strategies it is shown that an extended opportunistic maintenance optimization model has a good overall performance, and that it, for high values of the constant cost of performing maintenance, is preferable to perform opportunistic maintenance. The proposed models, applied to wind and nuclear power plants, could be extended and adapted to fit other components and systems.</p> / Reliability and cost centered maintenance methods

Face aux évolutions technologiques, à la complexité croissante des équipements industriels et à la dynamique des processus ainsi qu'aux changements organisationnels et à la mobilité du personnel, les responsables de maintenance cherchent à formaliser et pérenniser le savoir et le savoir-faire des employés. Pour répondre à cette problématique, notre objectif est de fournir un service d'aide à la maintenance qui utilise et capitalise les connaissances. Nos travaux se situent dans le cadre du projet Européen Proteus qui a permis de développer une plateforme distribuée d'e-maintenance intégrant les différents systèmes et applications existants en maintenance. Nous avons déterminé quatre niveaux d'applications associés chacun à un ensemble d'outils d'aide : le niveau d'analyse d'équipement, celui de diagnostic et d'expertise, celui de gestion des ressources et celui de gestion des stratégies de maintenance. Ces outils d'aide nécessitent une expertise capitalisée que nous proposons de préserver dans une mémoire d'entreprise. Afin d'élaborer la mémoire ainsi que notre outil d'aide au diagnostic et à la réparation, nous avons introduit une démarche de capitalisation des connaissances articulée autour d'une méthodologie de raisonnement à partir de cas (RàPC) guidé par les connaissances. La conception de l'outil passe par la modélisation des connaissances qui se décline en un modèle de représentation (une ontologie du domaine) et en un modèle de résolution de problèmes (RàPC). Les modèles proposés utilisent des technologies émergeantes du Web sémantique permettant de faire évoluer le concept d'emaintenance vers un nouveau concept de s-maintenance (maintenance sémantique).

The research study evaluated the effectiveness of a behavioral intervention for sleep maintenance insomnia in older adults. Twenty-two elders who spent 60 minutes or more awake during the night on a minimum of three nights per week for at least six months received treatment. The study utilized an experimental design with repeated measures. The subjects were randomly assigned to either an immediate or delayed (waiting list control) treatment group. Subjects completed daily sleep diaries and several other measures. The behavioral intervention was a treatment package consisting of sleep restriction therapy, stimulus control instructions, sleep education, and an optional daytime nap. A six-week treatment program consisting of four weekly classes and two weekly telephone interventions was implemented. Between and within group differences were identified using repeated measures analysis of variance (ANOVA). Post-hoc analyses were performed to identify significant differences. The between group analysis of sleep behaviors revealed an improvement in wake after sleep onset and sleep efficiency for the immediate treatment group. After intervention, the delayed treatment group improved on the same sleep behaviors as well as total sleep time. The therapeutic improvement was maintained at the three month follow-up. Sleep-wake impairment, dysfunctional cognitions, and presleep anxiety were reduced for both groups. The mood measures indicated that the subjects were not depressed prior to treatment and remained nondepressed following intervention. State and trait anxiety levels decreased. Favorable ratings for therapy evaluation were received. The majority of subjects felt they were compliant with treatment and had corresponding decreases in wake after sleep onset. In addition to statistical significance, the clinical significance of the study was established. Insomnia in older adults can be effectively treated using nonpharmacological intervention. Replication of the study is warranted as well as analysis to examine moderating factors affecting treatment outcomes. An effort should be made to increase the demographic diversity of subjects in future studies. Alternative treatment implementation modalities and settings other than the community should be considered for further research.

<p style="text-align: justify;">Vrednost objekata i njihova upotrebljivost opadaju vremenom usled neadekvatnog održavanja. Uobičajen model korektivnog održavanja postaje neprihvatljiv zbog toga što je ekonomski neodrživ. Reaktivno održavanje se zamenjuje proaktivnim održavanjem čijim se planiranjem nepredvidive intervencije svode na najmanju meru. To je moguće ostvariti uvođenjem savremene organizacije upravljanja održavanjem. Za kvalitetno održavanje neophodno je postojanje baze podataka koja omogućava planiranje i kontrolu aktivnosti na održavanju objekata.</p> / <p style="text-align: justify;">The value of buildings as well as their utilization declines over the time due to<br />inadequate maintenance. Usual method of corrective maintenance becomes<br />unacceptable due to its economic unsustainability. Reactive maintenance is<br />replaced by proactive maintenance the planning of which provides for<br />reduction of unpredictable interventions to the greatest possible extent. This<br />can be achieved by introducing modern organization of maintenance<br />management. With a view to establishing quality maintenance, it is<br />necessary to have the data base which enables planning and supervision of<br />building maintenance activities.</p>