Por estar diretamente sujeita a fatores econômicos de nível global, a mineração tende a se desenvolver para buscar processos produtivos mais enxutos, aliando menores custos operacionais a melhores taxas produtivas. Neste contexto, o objetivo principal deste trabalho é avaliar o comportamento geral da curva de tempo em manutenção preventiva de uma frota de caminhões em uma mineração de grande porte, sendo a análise realizada em uma janela temporal baseada em um período econômico de mínimo local nos preços do cobre. A partir do comportamento observado é feita uma discussão sob as premissas da metodologia de gestão nomeada Manutenção Produtiva Total de forma a se debater os possíveis principais riscos e/ou consequências que podem ser enfrentadas pelo projeto e como estas decisões qualitativamente indicam o grau de maturidade na integração operacional entre produção e manutenção em um projeto minerário. Ao final, pode-se concluir que ainda é necessário um intenso trabalho em se traduzir as premissas da MPT para a indústria mineral, buscando-se adaptar processos e métricas que sejam mais condizentes ao ambiente da indústria extrativa (que é muito diferente da indústria de manufatura, onde o programa teve início). Além disso, fica claro que a aplicação da MPT é possível e bem-vinda na mineração já havendo de vários estudos acadêmicos na área - ou seja, o ponto em questão mais desafiador provavelmente é que seja desenvolvido um programa de MPT de forma endógena em um projeto mineral. / As it is directly under global economic factors, the mining industry tends to develop to seek leaner production processes, combining lower operational costs to better productive rates. In this context, the main objective of this study is to evaluate the general behavior of the time spend in preventive maintenance of a truck fleet from a large-scale mining project, being the analysis performed in a time window based on an economic period of local minimum in copper prices. From the observed behavior a discussion is made under the assumptions of the management methodology named Total Productive Maintenance in order to discuss the possible main risks and/or consequences that can be faced by the project and how these decisions qualitatively indicate the degree of maturity between production and maintenance in a mining project. In the end, it can be concluded that an intense work is still needed to translate the TPM premises into the mineral industry, being necessary to seek ways to adapt processes and metrics that are more suited to the extractive industry environment (which is very different from the manufacturing industry, where the program started). In addition, it is clear that the application of TPM is possible and welcome in mining since there are several academic studies in the area - in other words, the most challenging point in question is probably that an endogenous TPM program is developed within a mineral project.

Syftet med denna uppsats är att undersöka en komponents    optimala utbyts" tid med hänsyn till kostnad och risk,    och föreslå schemalagda underhåll, med hjälp av statistiska metoder.    Genom att använda statistiska verktyg och historiska data, kan    en komponents samt systemets brister predikteras. När    forskaren vet hur ett system beter sig, kan dess fördelar    exploateras och tas till vara på. Schemaläggning av    förebyggande service, kostnads prognoser samt    uppskattning av förlängda garantier är möjliga fördelar som    kan nyttjas av denna rapport. Detta medför en högre    tillgänglighet och förbättrat rykte hos kund.    Tillförlitligthet teori är en viktigt del av    Total Quality Management, TQM, som säkerhetsställer kvalité.    I denna uppsats jämförs, förklaras och verifieras 2 kända ARP,    och strategin att ersätta endast då komponenten går sönder i en fallstudie.    Denna uppsats indikerar att en ARP med ändlig horisont ger mer optimalta resultat än    en ARP med oändlig horisont eller då ingen utbytespolicy används.    Barlow \& Proschan visade detta redan 1962.    I denna uppsats påvisas att ARP-teorier kan minska omkostnader och stilleståndstid    samt öka tillgängligheten. / The purpose of this thesis is to examine when a part's optimal   replacement time occurs in terms of risk and cost, and provide maintenance plans   accordingly using statistical methods.   With the use of statistical tools and historical data,   the failures of components as well as the system can be predicted.   Once the researcher knows how the system behaves, he/she can reveal the gains that   can be made. Scheduling of preventive maintenance, improved warranty cost   forecasts and estimation of lengthened warranty costs are   plausible benefits from this report. This will further result   in higher availability and improved reputation among clients.   Reliability theory is an important part of Total Quality Management (TQM),   ensuring good quality.   This thesis will compare the differences between two known age replacement policies (ARP),   and with the strategy of replacing only on failures in a real case-study.   This thesis indicates that an ARP with finite horizon yields   a more optimal solution than an ARP with infinite horizon as well as using no replacement policy at all.   Barlow & Proschan established this as far back as 1962.   With the aid of ARP theories it has been shown in this thesis that lowering costs is possible   and in the progress lower downtime which increases availability.

<p>Syftet med denna uppsats är att undersöka en komponents    optimala utbyts" tid med hänsyn till kostnad och risk,    och föreslå schemalagda underhåll, med hjälp av statistiska metoder.    Genom att använda statistiska verktyg och historiska data, kan    en komponents samt systemets brister predikteras. När    forskaren vet hur ett system beter sig, kan dess fördelar    exploateras och tas till vara på. Schemaläggning av    förebyggande service, kostnads prognoser samt    uppskattning av förlängda garantier är möjliga fördelar som    kan nyttjas av denna rapport. Detta medför en högre    tillgänglighet och förbättrat rykte hos kund.    Tillförlitligthet teori är en viktigt del av    Total Quality Management, TQM, som säkerhetsställer kvalité.    I denna uppsats jämförs, förklaras och verifieras 2 kända ARP,    och strategin att ersätta endast då komponenten går sönder i en fallstudie.    Denna uppsats indikerar att en ARP med ändlig horisont ger mer optimalta resultat än    en ARP med oändlig horisont eller då ingen utbytespolicy används.    Barlow \& Proschan visade detta redan 1962.    I denna uppsats påvisas att ARP-teorier kan minska omkostnader och stilleståndstid    samt öka tillgängligheten.</p> / <p>The purpose of this thesis is to examine when a part's optimal   replacement time occurs in terms of risk and cost, and provide maintenance plans   accordingly using statistical methods.   With the use of statistical tools and historical data,   the failures of components as well as the system can be predicted.   Once the researcher knows how the system behaves, he/she can reveal the gains that   can be made. Scheduling of preventive maintenance, improved warranty cost   forecasts and estimation of lengthened warranty costs are   plausible benefits from this report. This will further result   in higher availability and improved reputation among clients.   Reliability theory is an important part of Total Quality Management (TQM),   ensuring good quality.   This thesis will compare the differences between two known age replacement policies (ARP),   and with the strategy of replacing only on failures in a real case-study.   This thesis indicates that an ARP with finite horizon yields   a more optimal solution than an ARP with infinite horizon as well as using no replacement policy at all.   Barlow & Proschan established this as far back as 1962.   With the aid of ARP theories it has been shown in this thesis that lowering costs is possible   and in the progress lower downtime which increases availability.</p>

Företag kan använda sig av olika strategier för underhåll. Det kan vara avhjälpande underhåll som utförs först när ett fel uppkommer eller förebyggande underhåll. Ofta används en kombination av båda. Det förebyggande underhållet kan vara förutbestämt eller tillståndsbaserat. Fördelar med att använda sig av tillståndsbaserat underhåll är exempelvis att utbyte av enheter inte behöver ske i onödan utan först när en observation visar att ett fel är på väg att ske. Vid val av förebyggande underhåll kan RCM-metoden användas för att utröna vilka feltillstånd som kan uppstå och som orsakar funktionsfel. Val av förebyggande underhåll kan baseras på fakta om nya tekniker, felhistorik samt vilken utrustning och kompetens som finns tillgänglig. Volvo Cars i Skövde använder sig just nu av i stort sett likadant förebyggande underhåll på nya verktygsmaskiner som på gamla. Företaget använder sig av tillståndsbaserat underhåll på vissa komponenter och enheter. Det består då främst av inspektioner, subjektiva tillståndskontroller, och vibrationsövervakning på motorspindlar. Genom intervjuer framkommer att nya tekniker sällan införs och att lagda planer sällan ändras. Företaget är dock medvetet om att nya tekniker för tillståndsbaserat underhåll finns och är intresserat av att undersöka om ett utökat tillståndsbaserat underhåll är lämpligt på verktygsmaskiner. De tillståndsbaserade teknikerna som det talats om är främst ballbarmätning, övervakning av processparametrar och geometrisk verifiering. Ett underlag för att se om nya tekniker bör införas togs fram genom datainsamling av felhistorik på maskiner. Avgränsning gjordes genom att en fem år gammal bearbetningslinje för cylinderhuvuden studerades. Genom sortering av data från haverier ur underhållssystemet Maximo från de senaste åren och prioritering genom Paretoprincipen visade det sig att återkommande haverier på kulskruvar finns. Till komponenten finns ett tillståndsbaserat underhåll kopplat, den inspekteras en gång om året. Det är dock sällan som fel på komponenten upptäcks på inspektionen, bara fyra av tjugosju bytta kulskruvar de senaste fem åren är bytta efter anmärkning från inspektion. Genom att kartlägga komponentens haverier på femton verktygsmaskiner och när FU gjorts hittades flera förbättringsmöjligheter. Kostnaden för att byta kulskruv när väl fel uppstått är upp till tio gånger så stor jämfört med att byta den förebyggande. När fel uppstått har det medfört kassationer av producerade detaljer och lång stilleståndstid. Motiv för att införa ett bättre förebyggande underhåll finns därför framför allt i minskade kostnader och ökad tillgänglighet. Företaget rekommenderas att införa ballbarmätning som ett nytt tillståndsbaserat underhåll. Detta för att öka den objektiva kontrollen av mekaniska slitdelar. Mätmetoden är inte helt okänd för företaget och relativt lätt att införa. Den subjektiva kontrollen som görs idag bör göras om för att bättre fånga begynnelse till fel. Kontrollen kräver idag en hel del driftstoppstid vilket gjort att den inte utförts i tid och bör därför kortas ner. Företaget rekommenderas också att undersöka nya metoder för förebyggande underhåll kontinuerligt. Idag finns ingen anställd med uppdraget och för att utveckla underhållet måste företaget hålla sig uppdaterade på nya tekniker. / A company can use different strategies when performing maintenance. One strategy is corrective maintenance where maintenance is carried out after a failure has occurred. Another strategy is preventive maintenance. A combination of the two is often used. The preventive maintenance can be predetermined or condition based. Advantages with the condition based maintenance are e.g. that the replacement of parts can be planned according to observations indicating there’s an increasing risk of failure. When choosing preventive maintenance, the RCM method can be used to determine risk of failure modes and the cause of function failures. Decisions regarding the preventive maintenance should be based on knowledge in new techniques, history of failures and the equipment and competence available. Volvo Cars in Skövde is doing more or less the same preventive maintenance on machine tools regardless of whether it’s a new or old machine. The company is using condition based maintenance on some of the components and units. Mostly it consists of human inspections, a subjective control of the machine’s condition, and spindle vibration analysis. Through interviews it has been determined that new techniques are rarely implemented and that the decided maintenance plan for a machine is rarely changed. The company is aware of the development of new techniques for condition based maintenance and wants to investigate whether it is appropriate to evolve their condition based maintenance on machine tools. The techniques further investigated are measurement with Ball bar, monitoring of process parameters and geometrical verification. To make accurate decisions regarding the implementation of new techniques, a data collection of the history of frequent failures was done. To limit the amount of data a five year old processing line was studied. Data from the maintenance system Maximo was sorted by long failures from the recent years and by prioritizing with the Pareto principle it showed the recurring failures of ball screws. The component do have a condition based maintenance activity today, there is an inspection once a year. However, the inspection is rarely able to predict or find a failure on the ball screw. Four out of twenty-seven ball screws with fault have been changed after inspection over the last five years. By mapping the components failures on fifteen machine tools and when preventive maintenance has been done, several options for improvements were found. The cost of the replacement of a ball screw when a failure has already occurred is as much as ten times the cost of replacement before failure. This is caused by cost of scrap and long down time. A new, improved preventive maintenance task is therefore highly justified. The motif is both reducing the scrap cost related to failure and with increased availability. The company is recommended an investment in Ball bar as a new method for condition based maintenance. It should be used to increase the objective control of the mechanical parts of a machine tool. The method is not totally new for the company and relatively easy to implement. The current subjective control on the machine tools should be revised to increase the probability of finding degradation of functions. Today the activity takes rather long time and has therefore not been done in time, it should be shorter. The company is also recommended to investigate new methods for preventive maintenance continually. Today there is no employee with that mission and to evolve maintenance, the company has to be updated on new techniques.

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>

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.