The Experts below are selected from a list of 399 Experts worldwide ranked by ideXlab platform
Y Tang - One of the best experts on this subject based on the ideXlab platform.
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on changing points of mean residual life and failure rate function for some generalized weibull distributions
Reliability Engineering & System Safety, 2004Co-Authors: Y TangAbstract:Abstract The failure rate function and mean residual life function are two important characteristics in reliability analysis. Although many papers have studied distributions with Bathtub-shaped failure rate and their properties, few have focused on the underlying associations between the mean residual life and failure rate function of these distributions, especially with respect to their changing points. It is known that the change point for mean residual life can be much earlier than that of failure rate function. In fact, the failure rate function should be flat for a long period of time for a distribution to be useful in practice. When the difference between the change points is large, the flat portion tends to be longer. This paper investigates the change points and focuses on the difference of the changing points. The exponentiated Weibull, a modified Weibull, and an extended Weibull distribution, all with Bathtub-shaped failure rate function will be used. Some other issues related to the flatness of the Bathtub Curve are discussed.
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On the Change Points of Mean Residual Life and Failure Rate for Some Extended Weibull Distributions
2002Co-Authors: Y Tang, M. Xie, T.n. GohAbstract:The lifetime distribution of many complex systems exhibits Bathtub-shaped failure rate (BFR). In this paper, we investigate the association between the mean residual life (MRL) and failure rate (FR) of BFR distributions, especially with respect to their change points. Some generalizations of Weibull distribution that can be used to model Bathtub-shaped failure rate are used. The sensitivity of the change points to the parameters is discussed. Besides, it is also of interest to investigate for what parameters or what BFR distribution, the flat portion of Bathtub Curve is long. Although it is not always the case, when the relative difference between the change points is small, the flat portion tends to be longer
Joost Duflou - One of the best experts on this subject based on the ideXlab platform.
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forecasting the composition of emerging waste streams with sensitivity analysis a case study for photovoltaic pv panels in flanders
Resources Conservation and Recycling, 2017Co-Authors: Jef R Peeters, Diego Altamirano, Wim Dewulf, Joost DuflouAbstract:Abstract Forecasting emerging waste streams is challenging because of high uncertainty on the product lifetime and material composition, which should be taken into account to forecast the evolution in amount and composition of such waste streams. In addition, it is impossible to collect complete product lifetime data for emerging waste streams. For this reason, a method based on the theory of the Bathtub Curve, used in reliability engineering for taking account of large data uncertainties, is presented here and used to forecast the materials that will appear in emerging waste streams. The presented methodology is applied in a case study to forecast the material composition of waste from silicon based photovoltaic (PV) panels in the region of Flanders in Belgium. For this case study, the lifetime distribution of PV panels is determined based on the analysis of the amounts of waste collected by the European collection program “PV CYCLE”, as well as expert consultation. The results of the presented forecasts indicate not only that a wide variety of materials has been used in different concentrations in PV panels, but also that a high uncertainty remains on when these waste streams will have to be recycled. The results also demonstrate that up to 22,000 ton per year or up to 3.4 kg per capita of silicon based PV panels will have to be recycled in Flanders in the near feature, which means that up to 0.2% of the annual environmental impact of Flanders could be mitigated by targeting all materials present in EoL PV panels for closed loop recycling.
Bouzon Marina - One of the best experts on this subject based on the ideXlab platform.
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Remanufatura de de bens de consumo duráveis: um método de diagnóstico e análise de problemas
2012Co-Authors: Bouzon MarinaAbstract:Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-graduação em Engenharia Mecânica, Florianópolis, 2010A conscientização dos consumidores quanto aos seus direitos e à qualidade dos produtos tem aumentado o volume de devolução de bens de consumo duráveis aos locais de venda, de onde, por sua vez, são encaminhados para as indústrias. O destino final desses bens é uma questão que vem tomando importância devido às preocupações ambientais e sociais da atualidade. Adicionalmente, a fase de início de vida útil dos produtos apresenta um pico de taxa de falhas conforme expresso pela #curva da banheira# e, além disso, é nesse primeiro contato do consumidor com o produto que esses problemas funcionais/estéticos podem ser detectados, assim como os problemas de adequação ao uso podem ser percebidos. Assim, muitos produtos retornam às fábricas por #mortalidade infantil# ou inadequação ao uso, o que cria um problema de decisão em relação ao melhor destino que pode ser dado a esses bens. Uma vez retornados à fábrica, existem alguns cenários possíveis para esses produtos: remanufatura, reciclagem ou descarte; entretanto a decisão sobre os cenários é complexa, pois envolve fatores econômicos, de gestão, ambientais e sociais. Partindo dessas considerações, esta dissertação apresenta um método de estudo e análise multicriterial para o processo decisório acerca dos produtos que retornam precocemente de campo, que contribui no fornecimento de recomendações para o tratamento desses bens. Esse método foi motivado por um caso real de uma indústria de bens de consumo duráveis que remanufatura seus produtos retornados por #mortalidade infantil#. A concepção do método foi baseada na associação do estudo de caso nessa empresa com a literatura sobre retorno de produtos, remanufatura e apoio à decisão. O método é estruturado em três fases: um diagnóstico da situação atual do retorno dos produtos, que fornece embasamento para a segunda fase de apoio à decisão quanto à melhor tratativa para os bens e, por fim, a fase de orientações da manufatura enxuta para a criação de um sistema de remanufatura enxuto que diminua os efeitos da incerteza e variabilidade inerentes ao ambiente de recuperação de produtos.Consumers# awareness of their own rights and product quality has led to an increase in the volume of durable consumer goods that are returned to their sale points, from where they are sent back to the industries. These products# final destination is an issue that is gaining importance in view of the current environmental and social concerns. In addition, their early life period shows a peak of the failure rate as expressed by the "Bathtub Curve". It is during the consumer#s first contact with the product that functional/aesthetic or fitness-for-use problems are likely to be detected. Therefore, products are often returned to the industries due to "infant mortality" or unfitness for use, which creates a decision problem regarding the destination they will be given. Once back in the factory, three scenarios are possible: remanufacturing, recycling or disposal. The decision is complex because it involves economical, managerial, environmental and social issues. Based on these considerations, this thesis presents a method of study and multicriteria analysis designed to support the decision-making process regarding these early returning products, and provides recommendations for their treatment. The method was motivated by the real case of a durable consumer goods industry that remanufactures the products it receives back due to "infant mortality". It was designed with basis on the association of the case study with state-of-art literature on product return, remanufacturing and decision aiding. The method comprises three stages, starting with a current-state diagnosis of product return, which then supports the decision-aiding stage where the best treatment of the goods is advised. In the final stage, lean manufacturing guidelines are used to create a lean remanufacturing system that decreases the effects of inherent uncertainty and variability in the product recovery environment
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Remanufatura de de bens de consumo duráveis
2024Co-Authors: Bouzon MarinaAbstract:Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-graduação em Engenharia Mecânica, Florianópolis, 2010A conscientização dos consumidores quanto aos seus direitos e à qualidade dos produtos tem aumentado o volume de devolução de bens de consumo duráveis aos locais de venda, de onde, por sua vez, são encaminhados para as indústrias. O destino final desses bens é uma questão que vem tomando importância devido às preocupações ambientais e sociais da atualidade. Adicionalmente, a fase de início de vida útil dos produtos apresenta um pico de taxa de falhas conforme expresso pela #curva da banheira# e, além disso, é nesse primeiro contato do consumidor com o produto que esses problemas funcionais/estéticos podem ser detectados, assim como os problemas de adequação ao uso podem ser percebidos. Assim, muitos produtos retornam às fábricas por #mortalidade infantil# ou inadequação ao uso, o que cria um problema de decisão em relação ao melhor destino que pode ser dado a esses bens. Uma vez retornados à fábrica, existem alguns cenários possíveis para esses produtos: remanufatura, reciclagem ou descarte; entretanto a decisão sobre os cenários é complexa, pois envolve fatores econômicos, de gestão, ambientais e sociais. Partindo dessas considerações, esta dissertação apresenta um método de estudo e análise multicriterial para o processo decisório acerca dos produtos que retornam precocemente de campo, que contribui no fornecimento de recomendações para o tratamento desses bens. Esse método foi motivado por um caso real de uma indústria de bens de consumo duráveis que remanufatura seus produtos retornados por #mortalidade infantil#. A concepção do método foi baseada na associação do estudo de caso nessa empresa com a literatura sobre retorno de produtos, remanufatura e apoio à decisão. O método é estruturado em três fases: um diagnóstico da situação atual do retorno dos produtos, que fornece embasamento para a segunda fase de apoio à decisão quanto à melhor tratativa para os bens e, por fim, a fase de orientações da manufatura enxuta para a criação de um sistema de remanufatura enxuto que diminua os efeitos da incerteza e variabilidade inerentes ao ambiente de recuperação de produtos.Consumers# awareness of their own rights and product quality has led to an increase in the volume of durable consumer goods that are returned to their sale points, from where they are sent back to the industries. These products# final destination is an issue that is gaining importance in view of the current environmental and social concerns. In addition, their early life period shows a peak of the failure rate as expressed by the "Bathtub Curve". It is during the consumer#s first contact with the product that functional/aesthetic or fitness-for-use problems are likely to be detected. Therefore, products are often returned to the industries due to "infant mortality" or unfitness for use, which creates a decision problem regarding the destination they will be given. Once back in the factory, three scenarios are possible: remanufacturing, recycling or disposal. The decision is complex because it involves economical, managerial, environmental and social issues. Based on these considerations, this thesis presents a method of study and multicriteria analysis designed to support the decision-making process regarding these early returning products, and provides recommendations for their treatment. The method was motivated by the real case of a durable consumer goods industry that remanufactures the products it receives back due to "infant mortality". It was designed with basis on the association of the case study with state-of-art literature on product return, remanufacturing and decision aiding. The method comprises three stages, starting with a current-state diagnosis of product return, which then supports the decision-aiding stage where the best treatment of the goods is advised. In the final stage, lean manufacturing guidelines are used to create a lean remanufacturing system that decreases the effects of inherent uncertainty and variability in the product recovery environment
Filippos Amoiralis - One of the best experts on this subject based on the ideXlab platform.
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wind turbine reliability estimation for different assemblies and failure severity categories
Iet Renewable Power Generation, 2015Co-Authors: Christos Kaidis, Bahri Uzunoglu, Filippos AmoiralisAbstract:This study discusses the life-cycle analysis of wind turbines through the processing of operational data from three modern European wind farms. A methodology for supervisory control and data acquisition data processing has been developed combining previous research findings and experience from operational wind farms followed by statistical analysis of the results. The analysis was performed by dividing the wind turbine into assemblies and the failures events in severity categories. Depending on the failure severity category a different statistical methodology was applied, examining the reliability growth and the applicability of the ‘Bathtub Curve’ concept for wind turbine reliability analysis.
Jef R Peeters - One of the best experts on this subject based on the ideXlab platform.
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forecasting the composition of emerging waste streams with sensitivity analysis a case study for photovoltaic pv panels in flanders
Resources Conservation and Recycling, 2017Co-Authors: Jef R Peeters, Diego Altamirano, Wim Dewulf, Joost DuflouAbstract:Abstract Forecasting emerging waste streams is challenging because of high uncertainty on the product lifetime and material composition, which should be taken into account to forecast the evolution in amount and composition of such waste streams. In addition, it is impossible to collect complete product lifetime data for emerging waste streams. For this reason, a method based on the theory of the Bathtub Curve, used in reliability engineering for taking account of large data uncertainties, is presented here and used to forecast the materials that will appear in emerging waste streams. The presented methodology is applied in a case study to forecast the material composition of waste from silicon based photovoltaic (PV) panels in the region of Flanders in Belgium. For this case study, the lifetime distribution of PV panels is determined based on the analysis of the amounts of waste collected by the European collection program “PV CYCLE”, as well as expert consultation. The results of the presented forecasts indicate not only that a wide variety of materials has been used in different concentrations in PV panels, but also that a high uncertainty remains on when these waste streams will have to be recycled. The results also demonstrate that up to 22,000 ton per year or up to 3.4 kg per capita of silicon based PV panels will have to be recycled in Flanders in the near feature, which means that up to 0.2% of the annual environmental impact of Flanders could be mitigated by targeting all materials present in EoL PV panels for closed loop recycling.
