In the continuous manufacturing process which is used on Billerud Korsnäs in Gävle, maintenance of machinery and equipment is a major process. Through its work with continuous improvements, the mill has identified that the change of high-pressure feeder on line 1 is more time-consuming than the replacement of the other two high pressure feeders on the mill. The purpose and aim of the study is to streamline the replacement of high-pressure feeder by updating the preparation documentation, as well as the construction of a lift bar adjacent to the feeder, with a preliminary cost proposal. The zero-state analysis has been based on semi-structured individual interviews and close collaboration with a technician at the mill. Observations, measurements, strength calculations and a construction manual were used during the preliminary study of a lift beam adjacent to the feeder. Improvement opportunities were identified, analyzed and prioritized, which led to an action plan. Wasting can be reduced by setting up routine lists that are helpful during work-outs previously carried out by entrepreneurs. The introduction of pockets on the warehouse used during the change, as well as preventive maintenance on the chisel flange joint is recommended to increase the amount of weathering time during the change. The GAP analysis showed that up to 36 percent of the last maintenance effort may be due to waste in terms of waiting times and problems. The waste can be reduced by a good basis for preparation. The cost of the beam construction and a new lifting equipment amounted to SEK 832 thousand. Investment costs can be repaid within a reasonable time if the feeder is replaced by corrective maintenance. The lack of a fixed beam affects the length of the production stop to a limited extent in the event of a planned change, but the investment should provide a security improvement. Through the Gantt schedules and mapping of all the inputs, future processing work and replacement of high-pressure feeder will be carried out more efficiently. The documentation ensures that knowledge remains on the workplace and that the dependency of the persons is reduced. / Sammanfattning I den kontinuerliga tillverkningsprocessen på Billerud Korsnäs bruk i Gävle är underhåll av maskiner och utrustning en huvudprocess. Bruket har genom sitt arbete med ständiga förbättringar identifierat att bytet av högtryckskiken på linje 1 är mer tidskrävande än bytet av de två andra högtryckskikarna på bruket. Studiens syfte och mål var att effektivisera bytet av högtryckskiken genom upprättande av dokumentation som kan användas under beredning och byte. Konstruktion av en lyftbalk i anslutning till kiken och ett preliminärt kostnadsförslag var också en del av målet.   Nulägesanalysen har baserats på semistrukturerade enskilda intervjuer och nära samarbete med en tekniker på bruket. Observationer, mätningar, hållfasthetsberäkningar och en konstruktionshandbok användes under förstudien av en lyftbalk i anslutning till kiken. Förbättringsmöjligheter identifierades, analyserades och prioriterades, vilket slutligen ledde till en handlingsplan. Slöseri kan minskas genom att upprätta rutinlistor som är till hjälp under arbetsmoment som tidigare endast utförts av entreprenörer. Domkrafter som används under bytet rekommenderas att lagerhållas på förrådet. Förebyggande underhåll på kikens flänsförband ökar andelen värdeskapande tid under bytet. GAP- analysen visade att upp till 36 procent av den senaste underhållsinsatsen kan bero på slöseri i form av väntetider och problem. Slöseriet kan reduceras genom ett bra beredningsunderlag. Kiken är placerad högt upp på ett grettingplan. Befintliga rör gör det inte är möjligt att fästa en lyftbalk i taket. Flera delar ingår därför i konstruktionsförslaget, investering av balkkonstruktion och en ny lyftutrustning uppgick till 832 tusen kronor. Investeringskostnaderna kan återbetalas inom en rimlig tid om kiken byts genom avhjälpande underhåll. Avsaknaden av fast balk påverkar produktionsstoppets längd i liten utsträckning vid ett planerat byte, däremot skulle investeringen ge en säkerhetsmässig förbättring. Genom Ganttscheman och kartläggning av samtliga ingående arbetsmoment kommer framtida beredningsarbete och byte av högtryckskiken att utföras på ett mer effektivt sätt. Dokumentationen tillser att kunskap stannar på bruket och att personberoendet minskar.

Orientadores: Christiano Lyra Filho, Fábio Luiz Usberti / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-27T03:25:56Z (GMT). No. of bitstreams: 1 Bacalhau_EduardoTadeu_D.pdf: 1630102 bytes, checksum: 258db7b09d8ce71b7d9a577e1993a3c2 (MD5) Previous issue date: 2015 / Resumo: Este trabalho explora alternativas para a determinação das melhores políticas de planejamento das ações de manutenção preventiva em redes de distribuição de energia elétrica. O problema é uma extensão de abordagens da área de manutenção centrada em confiabilidade (MCC), que vem sendo objeto de pesquisas ao longo das últimas décadas. Por se tratar de um problema de otimização combinatória de difícil solução, são poucos os artigos publicados que envolvem sistemas de escala real, e a maioria dentre esses utiliza meta-heurísticas como estratégia de solução. A abordagem desenvolvida neste trabalho é baseada na técnica de otimização denominada programação dinâmica. Duas estratégias para a redução do espaço de busca são adotadas: uma delas procura identificar e eliminar soluções dominadas; a segunda estratégia envolve a aplicação do processo de otimização da programação dinâmica em torno de uma vizinhança de uma solução promissora, movendo iterativamente em um espaço de soluções --- uma abordagem inspirada na programação dinâmica diferencial discreta. A combinação dessas duas estratégias é denominada Programação Dinâmica com Reduções de Espaço de Estados (PDREE). O trabalho investiga também a construção de estratégias híbridas. Uma das alternativas utiliza um algoritmo genético híbrido para a construção de planos de manutenção iniciais de boa qualidade, posteriormente otimizados pela PDREE. A segunda estratégia híbrida utiliza a PDREE para a construção de boas populações iniciais de soluções, posteriormente otimizada pelo algoritmo genético híbrido. As abordagens desenvolvidas são aplicadas a problemas de escala real e comparadas à abordagem por algoritmo genético híbrido. Os resultados mostram que as ideias desenvolvidas na tese estendem o estado-da-arte sobre a otimização de políticas de manutenção em redes de distribuição de grande porte / Abstract: This work explores alternatives to determine the best planning policies for preventive maintenance on electric power distribution systems. The problem is an extension of approaches of the reliability-centered maintenance area that has been studied allong the last decades. Since this problem is a hard combinatorial optimization problem, there are few works that address real-life systems, and most of these works use methods based on metaheuristic as solution strategy. The approaches proposed in this work are based on the optimization technique named dynamic programming. Two strategies are developed to reduce the search space of dynamic programming: the first strategy seeks to identify and eliminate dominated solutions; the second strategy confines the dynamic programming optimization procedures to the neighborhood of good solutions that move iteratively in the solution space---an approach inspired by the discrete differential dynamic programming method. The combination of both strategies is denominated Dynamic Programming with State Space Reductions (DPSSR). The work also investigates the development of hybrid strategies. One of the alternatives uses a hybrid genetic algorithm to obtain a promising initial maintenance strategy, further optimized by the DPSSR. The second hybrid strategy uses the DPSSR for constructing an initial good population, further optimized by a hybrid genetic algorithm. All the approaches are applied to real-life problems and compared to a pure hybrid genetic algorithm approach. The results show that the ideas developed in the thesis improve the state-of-the-art in obtaining the best maintenance policies for large distribution networks / Doutorado / Automação / Doutor em Engenharia Elétrica

This thesis deals with the design of a new maintenance system of a powder coating line at ABB. The theoretical part describes history of maintenance, used maintenance methods, and types of organizational structure. The practical part describes the current state of maintenance of the production line, analysis of the situation, and subsequently design of the new maintenance system.

The master's thesis deals with maintenance in the theoretical part, this part is describing historical development and individual systems. Then explains concepts of vibro-diagnostics and electro-diagnostics. Further work will focus on complex maintenance systems such as Reliability Centered Maintenance (RCM). The implementation of RCM in the manufacturing company is the subject of a practical part.

<p>Highway infrastructure, including roads/pavements, contributes significantly to a country’s economic growth, quality of life improvement, and negative environmental impacts. Hence, highway agencies strive to make efficient and effective use of their limited funding to maintain their pavement infrastructure in good structural and functional conditions. This necessitates predicting pavement performance and scheduling maintenance interventions accurately and reliably by using appropriate performance modeling and maintenance optimization methodologies, while considering the impact of influential variables and the uncertainty inherent in pavement condition data.</p> <p> </p> <p>Despite the enormous research efforts toward stochastic pavement performance modeling and maintenance optimization, several research gaps still exist. Prior research has not provided a synthesis of Markovian models and their associated methodologies that could assist researchers and highway agencies in selecting the Markov methodology that is appropriate for use with the data available to the agency. In addition, past Markovian pavement performance models did not adequately account for the marginal effects of the preventive maintenance (PM) treatments due to the lack of historical PM data, resulting in potentially unreliable models. The primary components of a Markov model are the transition probability matrix, number of condition states (NCS), and length of duty cycle (LDC). Previous Markovian pavement performance models were developed using NCS and LDC based on data availability, pavement condition indicator and data collection frequency. However, the selection of NCS and LDC should also be based on producing pavement performance models with high levels of prediction accuracy. Prior stochastic pavement maintenance optimization models account for the uncertainty of the budget allocated to pavement preservation at the network level. Nevertheless, variables such as pavement condition deterioration and improvement that are also associated with uncertainty, were not included in stochastic optimization models due to the expected large size of the optimization problem.</p><p>The overarching goal of this dissertation is to contribute to filling these research gaps with a view to improving pavement management systems, helping to predict probabilistic pavement performance and schedule pavement preventive maintenance accurately and reliably. This study reviews Markovian pavement performance models using various Markov methodologies and transition probabilities estimation methods, presents a critical analysis of the different aspects of Markovian models as applied in the literature, reveals gaps in knowledge, and offers suggestions for bridging those gaps. This dissertation develops a decision tree which could be used by researchers and highway agencies to select appropriate Markov methodologies to model pavement performance under different conditions of data availability. The lack of consideration of pavement PM impacts into probabilistic pavement performance models due to absence of historical PM data may result in erroneous and often biased pavement condition predictions, leading to non-optimal pavement maintenance decisions. Hence, this research introduces and validates a hybrid approach to incorporate the impact of PM into probabilistic pavement performance models when historical PM data are limited or absent. The types of PM treatments and their times of application are estimated using two approaches: (1) Analysis of the state of practice of pavement maintenance through literature and expert surveys, and (2) Detection of PM times from probabilistic pavement performance curves. Using a newly developed optimization algorithm, the estimated times and types of PM treatments are integrated into pavement condition data. A non-homogeneous Markovian pavement performance model is developed by estimating the transition probabilities of pavement condition using the ordered-probit method. The developed hybrid approach and performance models are validated using cross-validation with out-of-sample data and through surveys of subject matter experts in pavement engineering and management. The results show that the hybrid approach and models developed can predict probabilistic pavement condition incorporating PM effects with an accuracy of 87%.</p><p>The key Markov chain methodologies, namely, homogeneous, staged-homogeneous, non-homogeneous, semi- and hidden Markov, have been used to develop stochastic pavement performance models. This dissertation hypothesizes that the NCS and LDC significantly influence the prediction accuracy of Markov models and that the nature of such influence varies across the different Markov methodologies. As such, this study develops and compares the Markovian pavement performance models using empirical data and investigates the sensitivity of Markovian model prediction accuracy to the NCS and LDC. The results indicate that the semi-Markov is generally statistically superior to the homogeneous and staged-homogeneous Markov (except in a few cases of NCS and LDC combinations) and that Markovian model prediction accuracy is significantly sensitive to the NCS and LDC: an increase in NCS improves the prediction accuracy until a certain NCS threshold after which the accuracy decreases, plausibly due to data overfitting. In addition, an increase in LDC improves the prediction accuracy when the NCS is small.</p><p>Scheduling pavement maintenance at road network level without considering the uncertainty of pavement condition deterioration and improvement over the long-term (typically, pavement design life) likely results in mistiming maintenance applications and less optimal decisions. Hence, this dissertation develops stochastic pavement maintenance optimization models that account for the uncertainty of pavement condition deterioration and improvement as well as the budget constraint. The objectives of the stochastic optimization models are to minimize the overall deterioration of road network condition while minimizing the total maintenance cost of the road network over a 20-year planning horizon (typical pavement design life). Multi-objective Genetic Algorithm (MOGA) is used because of its robust search capabilities, which lead to global optimal solutions. In order to reduce the number of combinations of solutions of stochastic MOGA models, three approaches are proposed and applied: (1) using PM treatments that are most commonly used by highway agencies, (2) clustering pavement sections based on their ages, and (3) creating a filtering constraint that applies a rest period after treatment applications. The results of the stochastic MOGA models show that the Pareto optimal solutions change significantly when the uncertainty of pavement condition deterioration and improvement is included.</p>

Preventive maintenance is a process employed to reduce probability of failure or degradation of equipment. When such a process is performed by humans without a computerized solution, human errors are bound to take place. A computerized solution could reduce human errors by automatically performing tasks which are prone to error. A React web and a React Native application are created to evaluate which framework is most suitable for use in a preventive maintenance process based on three criteria. The criteria are round-trip request times, lines of code and delivery time based on build size. Results show that the React web application outperforms the React Native application in all three categories.

Maintenance of medical equipment plays an important role in ensuring the healthcare quality so that the care can be conducted with minimal risk. Preventive maintenance is performed to maintain the equipment in satisfactory operating condition, while corrective maintenance is made when there is an unpredicted maintenance requirement. This study aims to determine what effect preventive maintenance has on corrective maintenance. A correlation analysis, regression analysis and survival analysis are performed on work-order data from 2000-2021. The results obtained indicate that increasing the number of preventive maintenances made to medical equipment will decrease the number of corrective maintenances required for the medical equipment.

Rapporten behandlar problemen med drift- och underhåll på vindkraftverk och hur man kan minska behovet av dessa genom övervakning av vindkraftverkens tillstånd. Målet med rapporten är att undersöka om det går att förutse när och hur ett vindkraftverk kommer behöva underhållas, samt beskriva de metoder som används för att förhindra slitage av turbinbladen. Forskningsfrågor som behandlas inkluderar tillståndsövervakning av vindturbiner och vilka metoder som används för att undvika slitage på turbinbladen. Arbetet kommer att utföras som en litteraturstudie eftersom det inte är möjligt med fältstudier av vindkraftverk. Viktiga frågor som besvaras är vilka faktorer som orsakar erosion och hur det leder till minskad effektivitet och produktionskapacitet hos vindkraftsparker. Vidare tas det upp hur underhåll utförs på vindkraftverken idag och hur det kan komma att ske i framtiden, med fokus på tillståndsövervakande system och olika skyddslösningar. Även skillnaden mellan landbaserad och havsbaserad vindkraft tas upp, samt olika stadier av erosionsutbredningen på turbinbladen och hur de påverkar energiproduktionen. Slutligen diskuteras olika lösningar för att minska sannolikheten för erosion, såsom att minska maxhastigheten under otjänligt väder. För havsbaserade vindkraftverk finns det svårigheter vad gäller byggande och underhåll, men fördelar som bättre vindförhållanden och möjlighet att bygga på djupare vatten. Flytande vindkraftverk används för att möjliggöra placering på djupare vatten och längre bort från land. Framtida vindkraftverk kommer ha större turbiner och högre torn, samtidigt som minskningar av energikostnaderna för både land- och havsbaserad vindkraft är trolig. SeaTwirl har en revolutionerande design där bladet roterar genom vertikalplanet, vilket minskar effekterna av erosionsbaserade skador som regndroppar och partiklar kan påföra. Dessa flytande vindkraftverk som är tänkta att placeras på havsytan har en relativt låg kostnad, lägre underhållsbehov och lägre materialåtgång, vilket gör dem konkurrenskraftiga. Framtida utveckling finns i form av exempelvis SR Energy som börjat dela ut "vindbonus" till de som bor nära vindkraftsparker. Ytterligare ett exempel är Modvion som använder trälaminat istället för stålkonstruktioner, vilket möjliggör enklare konstruktion, kräver färre inspektioner och material kan vid avveckling återanvändas vid husbyggen. / The report addresses the issues of operation and maintenance of wind turbines and how their need can be reduced through monitoring the condition of wind turbines. The aim of the report is to investigate whether it is possible to predict when and how a wind turbine will need to be maintained, as well as describe the methods used to prevent wear of the turbine blades. Research questions that are addressed include condition monitoring of wind turbines and the methods used to avoid wear on turbine blades. The work will be carried out as a literature study since it is not possible to do field studies of wind turbines. Important questions that are answered include what factors cause erosion and how it leads to reduced efficiency and production capacity of wind farms. Furthermore, it is discussed how maintenance is currently carried out on wind turbines and how it may be done in the future, with a focus on condition monitoring systems and various protective solutions. Also, the difference between land-based and offshore wind power is discussed, as well as different stages of blade erosion and how they affect energy production. Finally, different solutions to reduce the likelihood of erosion are discussed, such as reducing the maximum speed during inclement weather. For offshore wind turbines, there are difficulties with construction and maintenance, but advantages such as better wind conditions and the ability to build in deeper water. Floating wind turbines are used to enable placement in deeper water and farther from shore. Future wind turbines will have larger turbines and higher towers, while reducing energy costs for both land and offshore wind power is likely. SeaTwirl has a revolutionary design where the blade rotates through the vertical plane, which reduces the effects of erosion-based damage that raindrops and particles can cause. These floating wind turbines that are intended to be placed on the ocean surface have a relatively low cost, lower maintenance needs, and lower material consumption, making them competitive. Future developments include, for example, SR Energy, which has started to distribute "wind bonuses" to those who live near wind farms. Another example is Modvion, which uses wooden laminate instead of steel structures, enabling simpler construction, requiring fewer inspections, and allowing material reuse in building construction.

This investigation studied the level of knowledge that principals have concerning the maintenance of their schools. A questionnaire was developed to address three research questions. These research questions were: (1) what is the extent that facilities maintenance is an important issue for school principals? (2) in what specific areas of facilities maintenance do principals lack knowledge? and (3) in what specific areas does the lack of facilities maintenance knowledge by principals exceed 30%? A questionnaire was developed to gather data to analyze comparative relationships to the research questions. Data indicated that principals do believe facilities maintenance is an important issue. Reponses to the questionnaire indicated most principals have a general understanding of facilities maintenance in its broadest sense. However, the data supported that most principals lack knowledge concerning the specific facilities maintenance information and issues. Recommendations were made to address the lack of knowledge principals have concerning facilities maintenance. Recommendations were also made for additional research in the area of the principal's knowledge concerning facilities maintenance.

Examensarbetet genomfördes på AstraZeneca, Snäckviken hos fabriken API. Dess ångsystem har länge drabbats av oavsiktliga avbrott och detta har inte åtgärdats trots förebyggande insatser, vilket i sin tur har resulterat i produktionsbortfall. Syftet med denna studie är därmed att ta fram en långsiktig underhållsplan på komponentnivå som ska minska samtliga avbrott i ångsystemet. För att genomföra detta var det nödvändigt med litteraturstudier, avbrottanalys, nulägesanalys, besök på Snäckviken samt intervjuer. Studiens teoriavsnitt omfattades bland annat av väsentliga begrepp såsom underhåll, tidsbaserat- och tillståndsbaserat underhåll. Dessa termer bidrog till förståelsen av arbetet och framtagningen av resultatet och i sin tur även diskussionen. Det slutliga resultatet påvisade faktumet att det fanns tre komponenter som orsakade flest avbrott i systemet, och för en av dessa skapades det en underhållsplan. Planen omfattas av en underhållsbeskrivning, reservdelar/utbyteskomponenter, tidsutförande samt underhållsreperationer som inkluderar rekommenderad utförarkompetens. / The project was carried out at AstraZeneca, Snäckviken at the API factory. Its steam system has long been affected by unintentional interruptions and this has not been remedied despite preventive measures, which in turn has resulted in production losses. The purpose of this study is therefore to develop a long-term maintenance plan at component level that will reduce all interruptions in the steam system. To implement this, it was necessary with literature studies, current situation analysis, interruption analysis, visits to Snäckviken and interviews. The theoretical section of the study included, among other things, essential concepts such as maintenance, time-based- and condition-based maintenance. These terms contributed to the understanding of the study and the result, and in turn also the discussion. The result demonstrated the fact that there were three components that caused the most interruptions in the steam system, and for one of these a maintenance plan was created. The plan is covered by a maintenance description, spare parts / replacement