The Experts below are selected from a list of 143154 Experts worldwide ranked by ideXlab platform
Rui Cunha Marques - One of the best experts on this subject based on the ideXlab platform.
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the influence of the Operational Environment on the efficiency of water utilities
Journal of Environmental Management, 2011Co-Authors: Pedro Carvalho, Rui Cunha MarquesAbstract:Adjusting for the Operational Environment in studies of performance measurement is very important, otherwise the analysis may lead to unrealistic scores, especially when its influence on costs is high, such as in the water utilities. In this paper, we study the influence of exogenous variables on the water utilities performance by applying conditional efficiency measures based on the order-m method and its probabilistic formulation. We use a sample of 66 water utilities operating between 2002 and 2008, representing about 70% of the Portuguese population. Our research suggests that inefficiency of Portuguese water utilities is substantial for some utilities: several exogenous variables might influence it considerably. For example, regulation has a positive influence on efficiency but when drinking water supply and wastewater services are provided by the same utility or when the wholesale and retail activities are provided together, the performance is lower. The effect of ownership is inconclusive and the variables residential customers, water source, peak factor, and density of customers have a mixed influence on performance which varies according to their scores.
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how does the Operational Environment affect utility performance a parametric study on the waste sector
Resources Conservation and Recycling, 2011Co-Authors: Pedro Simoes, Rui Cunha MarquesAbstract:Abstract The urban waste treatment service has been a sensitive issue for the Portuguese governments in the past decades. Among other measures, the Environmental and economical issues led to the creation of a sector-specific regulator for the waste sector. Considering this atypical circumstance in the worldwide context it is worth studying the external factors that may influence the waste utilities efficiency along with the regulation role. In this regard, we applied the parametric approach of the stochastic frontier analysis to evaluate the influence of the Operational Environment on the urban waste services performance. The sample included 32 utilities responsible for the waste treatment service in Portugal. The results showed a negative influence of factors, such as the existence of regulation, the distance to the waste treatment facilities and the provision of other services on utility performance. We also observed some benefits from privatisation and incineration, although these options have some particular features.
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regulatory structures and Operational Environment in the portuguese waste sector
Waste Management, 2010Co-Authors: Pedro Simoes, Kristof De Witte, Rui Cunha MarquesAbstract:This research computes the influence of the Operational Environment on the efficiency of the Portuguese urban solid waste services. A sample of 29 solid waste utilities encompassing the whole continental country was used for this purpose. Particularly, we apply the non-parametric double bootstrap model to estimate the effect of various explanatory factors on robust data envelopment analysis estimates. In general, we find a significant influence of the Environmental context on the solid waste utilities' performance. The Environmental context is characterized by gross domestic product per capita, distance to treatment facilities, population density, regulation, type of management, composting and incineration services.
Tore Markeset - One of the best experts on this subject based on the ideXlab platform.
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application of reliability models with covariates in spare part prediction and optimization a case study
Reliability Engineering & System Safety, 2014Co-Authors: Abbas Barabadi, Javad Barabady, Tore MarkesetAbstract:The number of spare parts required for an item can be effectively estimated based on its reliability performance. The reliability characteristics of an item are influenced by different factors such as the Operational Environment, maintenance policy, operator skill, etc. However, in the majority of reliability based spare part provision studies, the effect of these influence factors has not been considered, and the only variable of interest is the operating time. The aim of this paper is to demonstrate the application of the available reliability models with covariates in the field of spare part predictions by means of a case study.
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reliability and spare parts estimation taking into consideration the Operational Environment a case study
Industrial Engineering and Engineering Management, 2012Co-Authors: Abbas Barabadi, Javad Barabady, Behzad Ghodrati, Tore MarkesetAbstract:Spare parts provision is a complex problem and requires an accurate model to analysis all factors that may affect the required number of spare parts. The number of spare parts required can be effectively estimated based on the reliability performance of the item. The reliability characteristics of an item are influenced not only by the operating time, but also by factors such as the Operational Environment. Therefore, for spare parts provisioning to be effective, the impact of these influence factors on the reliability performance of the item should be quantified. Hence, the statistical approach selected for reliability performance analysis must be able to handle the effect of these factors. One of the important models for reliability performance analysis that takes influence factors into account is the proportional hazard model (PHM), which has received less attention in the field of spare parts provisioning. In this paper the application of PHM to spare parts provision is discussed and demonstrated by a case study.
Pedro Simoes - One of the best experts on this subject based on the ideXlab platform.
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how does the Operational Environment affect utility performance a parametric study on the waste sector
Resources Conservation and Recycling, 2011Co-Authors: Pedro Simoes, Rui Cunha MarquesAbstract:Abstract The urban waste treatment service has been a sensitive issue for the Portuguese governments in the past decades. Among other measures, the Environmental and economical issues led to the creation of a sector-specific regulator for the waste sector. Considering this atypical circumstance in the worldwide context it is worth studying the external factors that may influence the waste utilities efficiency along with the regulation role. In this regard, we applied the parametric approach of the stochastic frontier analysis to evaluate the influence of the Operational Environment on the urban waste services performance. The sample included 32 utilities responsible for the waste treatment service in Portugal. The results showed a negative influence of factors, such as the existence of regulation, the distance to the waste treatment facilities and the provision of other services on utility performance. We also observed some benefits from privatisation and incineration, although these options have some particular features.
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regulatory structures and Operational Environment in the portuguese waste sector
Waste Management, 2010Co-Authors: Pedro Simoes, Kristof De Witte, Rui Cunha MarquesAbstract:This research computes the influence of the Operational Environment on the efficiency of the Portuguese urban solid waste services. A sample of 29 solid waste utilities encompassing the whole continental country was used for this purpose. Particularly, we apply the non-parametric double bootstrap model to estimate the effect of various explanatory factors on robust data envelopment analysis estimates. In general, we find a significant influence of the Environmental context on the solid waste utilities' performance. The Environmental context is characterized by gross domestic product per capita, distance to treatment facilities, population density, regulation, type of management, composting and incineration services.
Abbas Barabadi - One of the best experts on this subject based on the ideXlab platform.
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application of reliability models with covariates in spare part prediction and optimization a case study
Reliability Engineering & System Safety, 2014Co-Authors: Abbas Barabadi, Javad Barabady, Tore MarkesetAbstract:The number of spare parts required for an item can be effectively estimated based on its reliability performance. The reliability characteristics of an item are influenced by different factors such as the Operational Environment, maintenance policy, operator skill, etc. However, in the majority of reliability based spare part provision studies, the effect of these influence factors has not been considered, and the only variable of interest is the operating time. The aim of this paper is to demonstrate the application of the available reliability models with covariates in the field of spare part predictions by means of a case study.
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reliability and spare parts estimation taking into consideration the Operational Environment a case study
Industrial Engineering and Engineering Management, 2012Co-Authors: Abbas Barabadi, Javad Barabady, Behzad Ghodrati, Tore MarkesetAbstract:Spare parts provision is a complex problem and requires an accurate model to analysis all factors that may affect the required number of spare parts. The number of spare parts required can be effectively estimated based on the reliability performance of the item. The reliability characteristics of an item are influenced not only by the operating time, but also by factors such as the Operational Environment. Therefore, for spare parts provisioning to be effective, the impact of these influence factors on the reliability performance of the item should be quantified. Hence, the statistical approach selected for reliability performance analysis must be able to handle the effect of these factors. One of the important models for reliability performance analysis that takes influence factors into account is the proportional hazard model (PHM), which has received less attention in the field of spare parts provisioning. In this paper the application of PHM to spare parts provision is discussed and demonstrated by a case study.
Javad Barabady - One of the best experts on this subject based on the ideXlab platform.
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application of reliability models with covariates in spare part prediction and optimization a case study
Reliability Engineering & System Safety, 2014Co-Authors: Abbas Barabadi, Javad Barabady, Tore MarkesetAbstract:The number of spare parts required for an item can be effectively estimated based on its reliability performance. The reliability characteristics of an item are influenced by different factors such as the Operational Environment, maintenance policy, operator skill, etc. However, in the majority of reliability based spare part provision studies, the effect of these influence factors has not been considered, and the only variable of interest is the operating time. The aim of this paper is to demonstrate the application of the available reliability models with covariates in the field of spare part predictions by means of a case study.
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reliability and spare parts estimation taking into consideration the Operational Environment a case study
Industrial Engineering and Engineering Management, 2012Co-Authors: Abbas Barabadi, Javad Barabady, Behzad Ghodrati, Tore MarkesetAbstract:Spare parts provision is a complex problem and requires an accurate model to analysis all factors that may affect the required number of spare parts. The number of spare parts required can be effectively estimated based on the reliability performance of the item. The reliability characteristics of an item are influenced not only by the operating time, but also by factors such as the Operational Environment. Therefore, for spare parts provisioning to be effective, the impact of these influence factors on the reliability performance of the item should be quantified. Hence, the statistical approach selected for reliability performance analysis must be able to handle the effect of these factors. One of the important models for reliability performance analysis that takes influence factors into account is the proportional hazard model (PHM), which has received less attention in the field of spare parts provisioning. In this paper the application of PHM to spare parts provision is discussed and demonstrated by a case study.
