It is important to assess and communicate the risk to life and downtime associated with earthquake induced damage to structures. Thus, a previously developed four-diagram/four-step approach to assess direct losses associated with structural damage, a similar quantitative risk assessment technique is used to examine the indirect loss associated with death and downtime. The four-step approach is subdivided into four distinct tasks: (a) Hazard analysis, (b) Structural analysis, (c) Loss analysis of both direct and indirect losses and (d) The total loss estimation due to damage, death and downtime. This empirically calibrated model in the form of power curve is used by establishing losses corresponding to onset of damage state 5 (complete damage) and limiting upper losses. The utility of the approach is investigated for the bridges in both California and New Zealand regions with different detailing. Results show that death related losses for bridges are generally twice and downtime five times the direct damage losses. Thus, it is concluded that structures should be designed for more than just acceptable physical damage. It is shown that a marked improvement can be made by moving to a comprehensive damage avoidance design paradigm.

No description available.

Diploma thesis is analyses and optimizes downtimes in production of brake discs, to find causes of downtimes, quantifying the cost of downtimes and also proposing solutions. The thesis is divided into several parts. The first is the theoretical basis, which is the basis for the following two parts of the thesis, namely the analysis of the current state and technical-economic evaluation.

The dredging activity is increasing worldwide due to ships that require bigger drafts, and consequently deeper navigation channels. Some dredging projects requires the operation of cutter suction dredgers on open waters, once these are capable of removing compact sediments and rocks while still maintaining a good productivity. These facts motivated the creation of a weather driven downtime prediction software for this type of operation, based on simplified calculations of the main dredging systems of a CSD. The motions caused by waves, and the forces and moments caused on these dredgers by winds, waves and currents were analyzed in order to evaluate the influence of each parameter magnitude and direction on the behavior of the vessel. The main criteria of the dredger influenced by this conditions were determined by a literature review as being the swing winch required power, the interaction between the cutterhead and the soil, and the anchoring system resistance, this that can be both a spud pole system stress or the Christmas tree cable tension. In this research, only the spud pole system bending stress was considered. Three mathematical models were developed to represent those systems. Since the non-linearity of the relation between the reaction forces of the dredger and the soil was not an object of the study, this process is represented by a constant user defined reaction force and a horizontal cutterhead velocity model. The efficiency of these models were tested by applying them on a case study of the dredging of the Açu port on the Brazilian coast by the Taurus II dredger. Simultaneous wind, wave and current data data were used as input to these models by creating a time series scenario of the operation period. The results for both scenarios showed that the operation would be close to impossible due to wave generated dynamic stress on the spud pole. / A atividade de dragagem no mundo é cada vez mais significativa em função do aumento dos navios que operam em portos, estes que possuem maior calado e requerem, consequentemente, canais de navegação mais profundos. Alguns projetos de dragagem utilizam dragas de sucção e recalque em mar aberto, dada a capacidade destes equipamentos de remover sedimento compactado e rochas, ainda mantendo uma boa produtividade. Estes fatos motivaram a criação de um programa de previsão de downtime gerado por condições ambientais de dragas de sucção e recalque baseado em modelos matemáticos simplificados. Os movimentos causados por ondas, e as forças e momentos causados na draga por ventos, ondas e correntezas foram analisados de forma a se obter a influência da magnitude e direção de cada um destes parâmetros no comportamento da embarcação. Os principais sistemas da draga influenciados por estas condições foram determinados com base em uma revisão bibliográficas como sendo a potência requerida nos guinchos de varredura, a interação do cortador com o solo e a resistência do sistema de ancoragem, sendo este a tensão de flexão dinâmica na trave do spud ou as tensões de ancoragem pelo sistema de árvore de natal. Três modelos matemáticos foram desenvolvidos para representar estes sistemas. Considerando a não linearidade da interação entre a draga e o solo, este processo foi representado por uma força de reação definida pelo usuário e pela velocidade horizontal do cortador. A eficiência destes modelos foi testada ao aplicá-los em um estudo de caso da dragagem do porto de Açu, na costa brasileira pela draga Taurus II. Valores simultâneos de ondas, ventos e correnteza foram utilizadas como entrada nestes modelos, através da criação de um cenário hipotético de série temporal. Os resultados para ambos os casos demonstraram que a operação seria impossibilitada em função de tensões de flexão dinâmicas no spud maiores que o limite determinado.

Machine downtime, whether planned or unplanned, is intuitively costly to manufacturing organisations, but is often very difficult to quantify. The available literature showed that costing processes are rarely undertaken within manufacturing organisations. Where cost analyses have been undertaken, they generally have only valued a small proportion of the affected costs, leading to an overly conservative estimate. This thesis aimed to develop a cost of downtime model, with particular emphasis on the application of the model to Australia Post’s Flat Mail Optical Character Reader (FMOCR). The costing analysis determined a cost of downtime of $5,700,000 per annum, or an average cost of $138 per operational hour. The second section of this work focused on the use of the cost of downtime to objectively determine areas of opportunity for cost reduction on the FMOCR. This was the first time within Post that maintenance costs were considered along side of downtime for determining machine performance. Because of this, the results of the analysis revealed areas which have historically not been targeted for cost reduction. Further exploratory work was undertaken on the Flats Lift Module (FLM) and Auto Induction Station (AIS) Deceleration Belts through the comparison of the results against two additional FMOCR analysis programs. This research has demonstrated the development of a methodical and quantifiable cost of downtime for the FMOCR. This has been the first time that Post has endeavoured to examine the cost of downtime. It is also one of the very few methodologies for valuing downtime costs that has been proposed in literature. The work undertaken has also demonstrated how the cost of downtime can be incorporated into machine performance analysis with specific application to identifying high costs modules. The outcome of this report has both been the methodology for costing downtime, as well as a list of areas for cost reduction. In doing so, this thesis has outlined the two key deliverables presented at the outset of the research.

The dredging activity is increasing worldwide due to ships that require bigger drafts, and consequently deeper navigation channels. Some dredging projects requires the operation of cutter suction dredgers on open waters, once these are capable of removing compact sediments and rocks while still maintaining a good productivity. These facts motivated the creation of a weather driven downtime prediction software for this type of operation, based on simplified calculations of the main dredging systems of a CSD. The motions caused by waves, and the forces and moments caused on these dredgers by winds, waves and currents were analyzed in order to evaluate the influence of each parameter magnitude and direction on the behavior of the vessel. The main criteria of the dredger influenced by this conditions were determined by a literature review as being the swing winch required power, the interaction between the cutterhead and the soil, and the anchoring system resistance, this that can be both a spud pole system stress or the Christmas tree cable tension. In this research, only the spud pole system bending stress was considered. Three mathematical models were developed to represent those systems. Since the non-linearity of the relation between the reaction forces of the dredger and the soil was not an object of the study, this process is represented by a constant user defined reaction force and a horizontal cutterhead velocity model. The efficiency of these models were tested by applying them on a case study of the dredging of the Açu port on the Brazilian coast by the Taurus II dredger. Simultaneous wind, wave and current data data were used as input to these models by creating a time series scenario of the operation period. The results for both scenarios showed that the operation would be close to impossible due to wave generated dynamic stress on the spud pole. / A atividade de dragagem no mundo é cada vez mais significativa em função do aumento dos navios que operam em portos, estes que possuem maior calado e requerem, consequentemente, canais de navegação mais profundos. Alguns projetos de dragagem utilizam dragas de sucção e recalque em mar aberto, dada a capacidade destes equipamentos de remover sedimento compactado e rochas, ainda mantendo uma boa produtividade. Estes fatos motivaram a criação de um programa de previsão de downtime gerado por condições ambientais de dragas de sucção e recalque baseado em modelos matemáticos simplificados. Os movimentos causados por ondas, e as forças e momentos causados na draga por ventos, ondas e correntezas foram analisados de forma a se obter a influência da magnitude e direção de cada um destes parâmetros no comportamento da embarcação. Os principais sistemas da draga influenciados por estas condições foram determinados com base em uma revisão bibliográficas como sendo a potência requerida nos guinchos de varredura, a interação do cortador com o solo e a resistência do sistema de ancoragem, sendo este a tensão de flexão dinâmica na trave do spud ou as tensões de ancoragem pelo sistema de árvore de natal. Três modelos matemáticos foram desenvolvidos para representar estes sistemas. Considerando a não linearidade da interação entre a draga e o solo, este processo foi representado por uma força de reação definida pelo usuário e pela velocidade horizontal do cortador. A eficiência destes modelos foi testada ao aplicá-los em um estudo de caso da dragagem do porto de Açu, na costa brasileira pela draga Taurus II. Valores simultâneos de ondas, ventos e correnteza foram utilizadas como entrada nestes modelos, através da criação de um cenário hipotético de série temporal. Os resultados para ambos os casos demonstraram que a operação seria impossibilitada em função de tensões de flexão dinâmicas no spud maiores que o limite determinado.

Cellular networks in Africa have grown exponentially over the past 10 years and their data centres (DCs) on average consume 3 MW of electrical power. They require a reliable electrical power supply and can have a downtime loss of over a million dollars per hour. Power quality, reliability and availability have emerged as key issues for the successful operation of a data centre. Investigations are carried out into emerging technologies and their application in data centre power distribution systems for cellular networks in Africa. Best practices are applied to develop a power distribution system (PDS) with the objective of achieving optimal reliability and availability. Analytical techniques are applied to determine and compare the reliability and availability of various power systems. Minimal cut set simulations identify system weak points and confirm component selection. Components’ inherent characteristics (CIC) and system connectivity topology (SCT) are key factors in the improvement of data centre availability. The analysis practices can be used by engineers and managers as a basis for informed decision making in determining power system reliability and the availability of an existing or a new data centre design. Weak points in the PDS of a data centre causing downtime are identified through analysis, and accurate solutions can be determined to prevent or minimise downtime. System connectivity topology (SCT) techniques were identified that could increase the reliability and availability of data centres for cellular networks in Africa. These techniques include multiple incomers from the utility company, redundancy levels of critical equipment and parallel distribution paths. Two case studies were carried out on data centres for a cellular network, one in Nigeria and one in Cameroon. The reliability and availability of both data centres was improved, with substantial reduction in downtime per year. The outcome of the case studies shows the importance of designing and implementing the power distribution system with sufficient levels of redundancy for critical equipment, and parallel distribution paths. / MSc (Engineering Sciences in Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

Cellular networks in Africa have grown exponentially over the past 10 years and their data centres (DCs) on average consume 3 MW of electrical power. They require a reliable electrical power supply and can have a downtime loss of over a million dollars per hour. Power quality, reliability and availability have emerged as key issues for the successful operation of a data centre. Investigations are carried out into emerging technologies and their application in data centre power distribution systems for cellular networks in Africa. Best practices are applied to develop a power distribution system (PDS) with the objective of achieving optimal reliability and availability. Analytical techniques are applied to determine and compare the reliability and availability of various power systems. Minimal cut set simulations identify system weak points and confirm component selection. Components’ inherent characteristics (CIC) and system connectivity topology (SCT) are key factors in the improvement of data centre availability. The analysis practices can be used by engineers and managers as a basis for informed decision making in determining power system reliability and the availability of an existing or a new data centre design. Weak points in the PDS of a data centre causing downtime are identified through analysis, and accurate solutions can be determined to prevent or minimise downtime. System connectivity topology (SCT) techniques were identified that could increase the reliability and availability of data centres for cellular networks in Africa. These techniques include multiple incomers from the utility company, redundancy levels of critical equipment and parallel distribution paths. Two case studies were carried out on data centres for a cellular network, one in Nigeria and one in Cameroon. The reliability and availability of both data centres was improved, with substantial reduction in downtime per year. The outcome of the case studies shows the importance of designing and implementing the power distribution system with sufficient levels of redundancy for critical equipment, and parallel distribution paths. / MSc (Engineering Sciences in Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

Yes / Reliability is critical to the design, operation, maintenance, and performance assessment and improvement of wind turbines (WTs). This paper systematically reviews publicly available reliability data for both onshore and offshore WTs and investigates the impacts of reliability on the cost of energy. WT failure rates and downtimes, broken down by subassembly, are collated from 18 publicly available databases including over 18 000 WTs, corresponding to over 90 000 turbine‐years. The data are classified based on the types of data collected (failure rate and stop rate) and by onshore and offshore populations. A comprehensive analysis is performed to investigate WT subassembly reliability data variations, identify critical subassemblies, compare onshore and offshore WT reliability, and understand possible sources of uncertainty. Large variations in both failure rates and downtimes are observed, and the skew in failure rate distribution implies that large databases with low failure rates, despite their diverse populations, are less uncertain than more targeted surveys, which are easily skewed by WT type failures. A model is presented to evaluate the levelised cost of energy as a function of WT failure rates and downtimes. A numerical study proves a strong and nonlinear relationship between WT reliability and operation and maintenance expenditure as well as annual energy production. Together with the cost analysis model, the findings can help WT operators identify the optimal degree of reliability improvement to minimise the levelised cost of energy. / UK Engineering and Physical Sciences Research Council (EPSRC). Grant Number: EP/P009743/1

I det här arbetet eftersökte Scania IM en metod för att beräkna maskiners påverkan på output för en produktionslina vid driftstörningar. Metoden skulle kunna appliceras på en produktionslina med ett serie-parallellt flöde och arbetet utgick från en utvald lina där man bearbetar cylinderhuvuden. Vid framtagandet av beräkningsmetoden skapades det som i arbetet kallas för påverkansfaktor som tar fram vilken påverkan ett bortfall av en maskin i flödet har på flaskhalsutrustningen, som i sin tur står för den yttersta begränsningen för systemet. På seriella stationer erhålls en påverkansfaktor på 100 % men på stationer med parallell utrustning så finns det en kvarvarande kapacitet vid driftstopp av enstaka maskiner vilket är beroende av hur många maskiner samt vilken utnyttjandegrad de hade i ursprungsläget. Vid framtagandet av beräkningsmetoden togs inspiration från tidigare arbeten inom detta område men anpassades eller förenklades för att möta behoven från underhållsavdelningen. En utveckling av metoden gjordes även för att kunna analysera historiska data där information omproducerad variant saknas och då används ett viktat genomsnitt för påverkansfaktorn. Påverkansfaktorn bortser från buffertars påverkan på systemet men hur de ska inkorporeras undersöktes och därav togs ett förslag fram där kritisk driftstoppstid (critical downtime) används tillsammans med påverkansfaktorn för att ta hänsyn till såväl buffertar som parallell utrustning. Ett verktyg skapades för Scania IM för att underlätta användandet av framtagna beräkningsmetoder. Det som kvarstår efter avslutat arbete är att över tid testa de framtagna metoderna för att undersöka hur väl de överensstämmer med verkligt produktionsutfall. Detta kunde ej genomföras under gällande situation då produktionen ej var i drift enligt normalläge under tidsperioden för arbetet. / For this thesis, Scania IM sought a method for calculating the impact of machine downtime on the output of a production line. The method was created to be applied on a production line with a seriesparallel flow and was constructed based on a selected line where cylinder heads are machined. To achieve this a variable called impact factor was created that produces the effect an individual machines downtime has on the bottleneck equipment for the production line, which in turn accounts for the utmost limitation of the system. At serial stations, an impact factor of 100% is obtained, but at stations with parallel equipment, there is a remaining capacity if at least one machine is functioning. The amount on remaining capacity is dependent on how many of the parallel machines that are malfunctioning and the degree of utilization they had in the original state. In developing the calculation method, inspiration was taken from previous work regarding similar subjects, but it was either adapted or simplified to meet the needs of the maintenance department for the production line. A further development of the method was also made to be able to analyze historical data where information on the produced variant of cylinder heads is missing which led to the use of a weighted average for the impact factor. The impact factor ignores the effects of buffers on the system output, but how they are to be incorporated was investigated and a proposal was therefore made where critical downtime is used together with the impact factor to take into account both buffers and parallel equipment. A tool was created for Scania IM where they can perform these calculations. What remains after completion of the thesis is to test the developed methods over time to examine how well they correspond to actual production data. This could not be done during the time of this thesis due to the current situation when production was not operating according to normal conditions.