The existence of variation has been a major problem within industry since the early days of the industrial revolution and perhaps even earlier. The fact that two parts not ever will be identical, forces every organisation to find a strategy for how to master variation. Process capability studies, a method designed to judge whether a process is capable or not, often plays an important part in such a strategy.The concept of process capability studies has received both positive and negative criticism during the last decade. For instance, the supporters of process capability studies emphasise the importance of using the method to identify improvement priorities to be focused in the overall improvement process within an organisation.However, as all methods, process capability studies has its limitations. Actually, it is not principally the method as such that has been criticised, but rather the measures of capability used when conducting process capability studies, the so called process capability indices. All existing process capability indices have some weaknesses, even the most sophisticated indices have relatively poor statistical properties which might lead the user to make incorrect decisions, even if most theoretical aspects of how to conduct process capability studies are known by the user. The use of process capability indices is for instance partly based on the assumption that the process output is normally distributed, a condition that is often not fulfilled in practice, where it is common that the process output is more or less skewed.This thesis focuses on process capability studies in both theory and practice. In part 1 of the thesis some theoretical aspects of how to conduct process capability studies are identified and then the adherence to these aspects within Swedish industry is investigated. This study reveals that there are certain gaps between how process capability studies are supposed to be conducted according to theory and the way they actually are carried out in practice. The study also tries to explain why these gaps exist, by analysing common obstacles when implementing and conducting process capability studies.In part 2, a simulation study focusing on the effects of skewness on estimates of some process capability indices belonging to the family of indices named Cis presented. The effects of skewness are studied in three different cases, one incapable case, one case just capable and one very capable case. In all cases, four lognormal distributions with different skewness are used. The results from the simulation study indicate that the effect of skewness is relatively systematic, and therefore there are some hope that future investigations might use these results when formulating some practical solution to the problem of how to use process capability indices when the process monitored has a skewly distributed output.Finally, the results are summarised and discussed and some suggestions for future research are given.

Alkali Aggregate Reaction (AAR) is a deterioration mechanism which affects concrete structures all over the world. Different parts of the world employ various mitigation and control measures for AAR damage. Different tests are also performed worldwide to assess AAR. With the variety of AAR avoidance measures and AAR tests performed worldwide, it is necessary to have a thorough compilation and critical assessment of these AAR avoidance measures and AAR tests, which may be of assistance to engineers and other professionals who are involved in structural and material design of concrete structures or in the construction, quality control and condition monitoring and assessment of concrete structures. This dissertation aims to outline the types of AAR and the mechanisms associated with them, and to highlight case studies of AAR incidences around the world. This dissertation further aims to provide a comprehensive compilation and analysis of various AAR avoidance measures as well as AAR tests that are performed worldwide. Commonalities and differences will be highlighted between the different case studies, and critical analyses will be done on the AAR avoidance measures and AAR tests that will be discussed. There are three main types of AAR, distinguishable by the aggregate source. These are: AlkaliSilica Reaction (ASR), Alkali-Silicate Reaction and Alkali-Carbonate Rock Reaction (ACR). Since AAR is a type of internal chemical damage to concrete, it can be avoided by engineering design and by carefully selecting the concrete construction materials. In order for damaging AAR to occur in concrete, the following conditions need to be met: • Reactive silica in the aggregates should be present • Alkali, which is primarily from Portland cement, should be of a sufficient concentration • There should be sufficient moisture in the concrete • Portlandite should be in a sufficient concentration (this is specifically for ACR) To prevent the occurrence of AAR in concrete, one or more of the conditions above should be eliminated, except for the case of ASR in which one or more of the first three conditions should be eliminated. Since this dissertation mainly focuses on ASR, only the first three conditions will be considered as these are the only conditions for the occurrence of ASR. Various testing methods are employed all over the world to assess AAR. These tests include tests performed to assess whether certain aggregates are susceptible to AAR; tests to assess the performance of specific concrete mixes and thus determine if they are susceptible to AAR, and also tests performed to assess the occurrence and extent of AAR in existing concrete structures.

Diplomová práca sa zaoberá návrhom a realizáciou inteligentného optimalizačného modulu pre podnikový informačný systém. Optimalizačný modul bude vytvárať celoročné plány údržby s rovnomerným množstvom údržbárskych aktivít v jednotlivých týždňoch a plány pre výrobu s pravidelnými odstávkami. V úvode je uvedený prehľad použiteľných optimalizačných metód, z ktorých sú vybrané metódy pre ďalšiu fázu, testovanie. Nelineárna metóda najmenších štvorcov z Matlab Optimization Toolbox, genetický algoritmus a ABC algoritmus budú otestované na zadanej plánovacej úlohe. Na základe výsledkov testu bude najlepšia metóda implementovaná v podnikovom informačnom systéme. Takto doplnený informačný systém umožňuje vytvárať kvalitnejšie plány údržby a tým zvýšiť celkovú efektivitu podniku.

Increased demands on productivity, quality and cost-efficiency affecting manufacturing trends towards increased complexity and higher degree of process automation. A major break down in such a manufacturing system may generate severe damage on productivity, environment and personnel. Using risk assessment to identify serve risks within a plant, in combination with different maintenance strategies, is one course of action to prioritising maintenance activities needed. A methodology for executing a so-called risk-based maintenance is reliability-centred maintenance, RCM. There are several benefits generated from RCM, for example, improved safety and maintenance cost-effectiveness. Though, several companies have problems to make it work. The problems that occur are many times within management and organisational (M&amp;O) aspects, such as lack of communication and management support. Some M&amp;O aspects of importance when introducing improvement methods as TQM and TPM are similar with the ones valid for RCM. Though, differences seem to depend on the use of RCM in a more technology environment, overshadow the affects M&amp;O aspects really bring about when introducing it. That is probably the main reason why obstacles occur when introducing RCM. A structured step model has been developed, focusing on the preparation and planning activities when introducing RCM. / <p>Godkänd; 1999; 20070403 (ysko)</p>

In many Western countries today, not least in Sweden, there are a lot of organizations that have great problems with sickness absence. The costs connected to the high rates of sickness absence have also risen to alarming levels. Healthy co-workers and healthy organizations are obvious goals for many leaders, but this is not always so easy to establish. Work practices and leadership that are beneficial to co-worker health are thus vital to identify. Studies have shown relationships between company-wide implementation of quality programs and improved co-worker satisfaction along with low co-worker turn over; in other words, co-worker health along with improved customer satisfaction and financial results. Despite the great problems concerning sickness absence, there are organizations that have been awarded prizes for excellence in leadership, internal partnership, working environment, and profitability. The overall purposes of the research described in this thesis are to examine and describe how management and leadership can establish sustainable health among the co-workers and examine how the leadership for sustainable health is related to Quality Management. The in-depth purpose is to examine which aspects within the values derived from the quality movement are those that primarily influence the co-workers' perceived health. The results presented can be described in three parts and are results from four case studies carried out in five different organizations. Three of the organizations have received awards for establishing good working environment, good financial results, and low sick leaves among their co- workers; the fourth received an award for the successful implementation of quality programs. The first part consists of results from case studies in three different organizations and describes how organizations can work to achieve sustainable health among their co-workers, with practical examples. The results are methodologies, values and organizational structure, which it is considered possible for other organizations to adopt in their efforts to achieve good working conditions resulting in fewer sick leaves. The second part is an attempt to investigate if leadership for sustainable health is related to Quality Management. Methodologies, leadership values, organizational structure, and general values found in organizations which have achieved sustainable health are analyzed in the light of Deming's 14 points, and a correlation is indicated. There is also correlation found between the TQM values and the co-workers' perception of their health. The third part examines which of the aspects within the values grown from the quality movement are those that influence the co-workers perceived health. The results show significant correlation between the values and the co-workers' perception of their health. Aspects found within the value "Top management commitment" were named; Empathy, Presence and Communication, Integrity, and Continuity. Within the value "Let everybody be committed" the aspects; Development, Influence and Being informed were found. These aspects are described in more detail and also in one model per value. The result implies that the TQM values; "Top management commitment", "Improve continuously" "Let everybody be Committed" and "Focus on customers" are important for achieving healthy organizations and sustainable health among co-workers. / <p>Godkänd; 2006; 20061206 (pafi)</p>

The main purpose of this research study is to test the applicability of the DER (Degree of defect, Extent and Relevancy of defect) rating system, used for road network infrastructures, to the support structures of a dry cooling tower in a power generation environment. The DER is a defect-based rating system developed locally by the Built Environment Division of the Council for Scientific and Industrial Research (CSIR) in Pretoria, South Africa. This study involved a visual inspection and the rating and analysis of defects of reinforced concrete (RC) structures in an Eskom power generation plant located in Grootvlei in Mpumalanga Province. Visual inspection and condition rating systems form part of an Asset Management System (AMS) that is used to ensure a safe operation and the economic benefit of the structure throughout its life cycle. For that reason, various organisations and roads authorities have developed condition-rating systems similar to the DER for visual assessment of their road network structures using a Bridge Management System (BMS) as a vehicle to achieve their operation and maintenance objectives. Other condition-rating systems have been identified and their applicability to structures in a power generation environment as compared to that of the DER was also tested. These condition-rating systems are: 1) The Overall Structural Condition Index (OSCI) - proposed by the Australasian Transport Research Forum (ATRF) for bridge condition assessment and prioritisation of maintenance activities and budget allocation. 2) The National Bridge Inspection Standard (NBIS) which establishes a uniform program for all state departments of transportation in the USA to regulate the minimum requirements for inspection types and procedures, inspection intervals, inspector qualifications, and inventory reporting, and 3) The Ontario Structure Inspection Manual (OSIM) which sets standards and provides uniform approaches for visual and detailed inspections and condition evaluation for all types of bridge structures in Ontario, Canada. Comparative rating analyses of the defects of the same RC structure in a power generation environment was conducted in order to establish the applicability of the DER in comparison with the other rating systems. The use of the DER, amongst other selected condition rating systems, was recommended with the suggestion that further improvement be undertaken so as to extend its usage within a power generation environment.

Central to the South African government’s vision of providing services to all is on-going maintenance of public infrastructure. Since 1994 the government focused on addressing backlogs in the provision of water services through new infrastructure investment; however it failed to make sufficient investment in the maintenance and renewal of this infrastructure (SAICE, 2006). Older infrastructure is not being renewed or refurbished as required and planned preventative maintenance on new infrastructure is inadequate (SAICE, 2006). This has been generally attributed to poor management strategies that are exacerbated by lack of skills in water services utilities and low levels of funding provisions (Mescht &amp; Jaarsveld, 2012; FFC, 2013). The continuing poor maintenance of water distribution networks has contributed to high leakage rates in South Africa (FFC, 2013; DBSA, 2012). To address challenges of maintenance of water distribution infrastructure a regulatory framework to guide municipalities is critical. The government approved the National Infrastructure Management Strategy (NIMS) in 2006 to support simultaneous infrastructure investment and maintenance (CIDB, 2008). One of the key thrusts of the strategy is the strengthening of the regulatory framework that governs planning and budgeting for maintenance. The literature survey of this study found that initiatives associated with the NIMS were very slow in gaining traction. The study reviews water services infrastructure management frameworks that are based on present legislative instruments and standards for two study areas; City of Capetown and City of Johannesburg. Challenges associated with effective management of water distribution infrastructure are assessed based on established infrastructure management policies, strategies and asset management plans for each entity. For each study area leakage control strategies are the key maintenance strategy outputs associated with the implementation of the management frameworks; therefore the study reviewed sector plans and annual reports to assess challenges associated with carrying out effective maintenance. The findings of the study show a correlation between the adoption of maintenance management strategies and the improvement of the performance of water distribution networks for both Cape Town and Johannesburg. The strategies are driven at the highest level of decision making in the municipalities as budgeting requirements are supported by the Integrated Development Plans of each study area. The maintenance allocations however remain below the international benchmark to enable the municipal entities to carry out satisfactory maintenance of their distribution infrastructure.

South Africa is considered a water-scarce country and this fact alone stresses the absolute need to preserve its water resources. As time goes by, the ageing of dams in South Africa is becoming an increasingly important factor to consider from a dam safety perspective. When considering concrete dams, Alkali Aggregate Reactions (AAR) which is the collective term referring to the potential chemical reactions between the cement and the coarse aggregate in the concrete, are a major cause of ageing. AAR causes internal swelling of concrete leading to stresses that eventually manifest on a macroscopic level as inter alia cracks, deformation and opening of horizontal construction joints. Although the effect of AAR expansion on arch dams is complex, certain behavioural phenomena have been identified as typical indicators of swelling concrete. These are well covered by literature. This thesis aims to compare the structural behaviour of concrete arch dams in South Africa that are subjected to swelling due to AAR. Three arch dams, namely Hartebeeskuil Dam, Poortjieskloof Dam and Thabina Dam (all located in different climatic regions), were identified and their behavioural patterns were investigated by using visual techniques along with the interpretation of instrumentation results. The typical instrumentation results that were used for interpretation purposes included geodetic surveying results, crack width gauge results, in situ stress measurement results and trivec measurement results. Poortjieskloof Dam, the oldest of the three dams, showed permanent upstream displacement trends of both flanks, but the centre of the arch showed a downstream displacement trend. Both flanks show swelling towards the abutments and rising crest levels are evident throughout the length of the dam wall. The dam wall was cracked quite severely on the downstream face and the horizontal joints showed clear separation. The most recent displacement trends suggest that the rate of AAR is decreasing. Hartebeeskuil Dam, the second oldest of the three dams, showed permanent upstream displacement trends throughout the length of the dam wall. Both flanks show swelling towards the abutments and crest levels at both flanks show some settlement. The central section of the arch show rising crest levels. The results of in situ stress measurements carried out in 1999 showed that the downstream section of the arch is experiencing tensile stresses while the upstream section of the arch is mostly experiencing compressive stresses. The cracking patterns on both the upstream and downstream faces seem to agree with these findings. The results generally seem to suggest that the AAR mainly occurs on the upstream side of the arch and that the effective arch has become thinner due to the tension zone on the downstream side. The most recent displacement trends suggest that the rate of AAR is not showing any signs of decreasing. Thabina Dam, the youngest of the three dams, showed permanent upstream trends of the right flank while the central region and left flank of the arch showed downstream trends. The flanks have moved permanently towards each other and the crest levels have increased throughout the length of the arch section. The most recent trends show increasing rates of strain especially in the vertical (z) and tangential (y) directions. More recently the entire arch has started showing upstream displacement trends. These may indicate the onset of a swelling mechanism in the concrete, most likely AAR, but extensive testing is required to prove this.

Design of Experiments (DoE) contains techniques, such as factorial designs, that help experimenters maximize the information output from conducted experiments and minimize the amount of experimental work required to reach statistically significant results. The use of DoE in industrial processes is frequently and thoroughly described in literature. However, continuous processes in industry, frequently found in, for example, the mining and steel industries, highlight special issues that are typically not addressed in the DoE literature. The purpose of this research is to contribute to an increased knowledge of the use of DoE in continuous processes and aims to investigate if factorial designs and other existing techniques in the DoE field are effective tools also in continuous processes. Two studies have been performed. The focus of the first study, a case study of an industrial blast furnace operation, is to explore the potential of using factorial designs in a continuous process and to develop an effective analysis procedure for the experiments in a continuous process. The first study includes, for example, interviews, experiments, and large elements of action research. The focus of the second study is to explore how a-priori process knowledge can be used to increase the analysis sensitivity for unreplicated experiments. The second study includes a metastudy of experiments in literature as well as an experiment. The results show that it is possible to use factorial designs in a continuous process even though it is not straightforward and special considerations by the experimenter will be required. For example, the dynamic nature of continuous processes affects the minimum time required for each run in an experiment since a transient time period is needed between each run to allow the experimental treatments to reach full effect in the process. Therefore, the use of split-plot designs is recommended since it can be hard to completely randomize the experimental run order. It is also found that process control, during the conduction of the experiment, may be unavoidable in continuous processes. Thus, developing a process control strategy during the planning phase is found to be an important experimental success factor. Furthermore, the results indicate that the multitude of cross-correlated response variables typical for continuous processes can be problematic during the planning phase of the experiment. The many and cross-correlated response variables are also reasons to why multivariate statistical techniques, such as principal component analysis, can make an important contribution during the analysis. Moreover, a-priori process knowledge is confirmed to have a positive effect on analysis sensitivity for unreplicated experiments. Since experimental effects in continuous processes can be expected to be small compared to noise, a-priori process knowledge can also make a valuable contribution during analysis of experiments in continuous processes. Furthermore, activities like coordination of people, information and communication as well as logistics planning are found as important parts of the experimental effort in continuous processes. / Försöksplanering innehåller metoder och verktyg, exempelvis faktorförsök, som hjälper den som utför experiment att maximera informationsutbytet från experimenten och samtidigt minimera mängden resurser som krävs för att nå statistiskt säkerställda resultat. Användandet av försöksplanering i industriella processer beskrivs ofta och utförligt i litteraturen, men kontinuerliga tillverkningsprocesser, som ofta hittas i exempelvis gruv- och stålindustrin, medför en problematik som normalt inte beskrivs i försöksplaneringslitteratur. Syftet med forskningen i denna avhandling är att bidra till en ökad kunskap om användandet av försöksplanering i kontinuerliga processer genom att undersöka om faktorförsök och andra verktyg inom försöksplaneringsområdet är effektiva också i kontinuerliga processer. För att uppnå syftet genomfördes två studier. Den första studien är en fallstudie vid en industriell masugnsanläggning. Här utreds, genom intervjuer, experiment och aktionsforskning, potentialen i att använda faktorförsök i en kontinuerlig process och en analysmetodik för experiment i kontinuerliga processer utvecklas. Den andra studien undersöker, genom en metastudie av experiment från litteratur samt ett experiment, hur a-priori processkunskap kan användas för att öka känsligheten i analys av icke upprepade experiment. Resultaten visar att det är möjligt att använda faktorförsök i en kontinuerlig process men att det kräver speciella överväganden av försöksplaneraren. Exempelvis påverkar den dynamiska karaktären hos kontinuerliga processer den minsta möjliga tid som krävs för varje delförsök eftersom en omställningstid, mellan varje delförsök, behövs för att de förändringar som görs ska nå full effekt i processen. Det kan därför vara svårt att använda en fullständigt randomiserad försöksording. Istället rekommenderas användningen av så kallade split-plot-försök där begränsningar i randomiseringsordningen görs. Vidare är processtyrning ofta oundvikligt samtidigt som experimenten pågår, vilket gör det viktigt att i förväg formulera en styrstrategi för att minimera styrningens påverkan på försöksresultaten. Resultaten visar också att den stora mängden korskorrelerade resultatvariabler, som är vanliga i kontinuerliga processer, kan skapa problem under planeringen av experimenten. De många och korskorrelerade resultatvariablerna är också en orsak till att multivariata statistiska verktyg, som t.ex. principalkomponentanalys, kan vara värdefulla hjälpmedel under analysen. Vidare visar resultaten att nyttjandet av a-priori processkunskap under analysen har en positiv effekt på analysresultaten för icke upprepade försök. Eftersom effekter av förändringar i kontinuerliga processer ofta förväntas vara små jämfört med brus kan a-priori processkunskap ge ett värdefullt bidrag vid analys av experiment i kontinuerliga processer. Resultaten visar också på vikten av exempelvis koordination av personal, information, kommunikation och logistikplanering för att lyckas bra med ett experiment i en kontinuerlig process. / <p>ISRN: LTU-LIC--07/66--SE</p>

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / One of the main problems existing in manufacturing companies is the high frequency of machine breakdowns and their high repair time. Therefore, over time, various maintenance strategies seeking to more efficiently manage the scheduled jobs have been presented. However, these are not always as effective as expected, because they are not properly applied, the resources are not available, or the strategy is not aimed at directly solving the problem. Based on the aforementioned, this paper proposes an integral model of maintenance management based on the principles of total productive maintenance and reliability-centered maintenance methodologies in order to increase machine availability in a company in the manufacturing sector. To validate this proposal, a pilot project will be developed to measure the impact that is being sought.