Consider a repairable system operating under a maintenance strategy that calls for complete preventive repair actions at pre-scheduled times and minimal repair actions whenever a failure occurs. Under minimal repair, the failures are assumed to follow a nonhomogeneous Poisson process with an increasing intensity function. This paper departs from the usual power-law-process parametric approach by using the constrained nonparametric maximum likelihood estimate of the intensity function to estimate the optimum preventive maintenance policy. Several strategies to bootstrap the failure times and construct confidence intervals for the optimal maintenance periodicity are presented and discussed. The methodology is applied to a real data set concerning the failure histories of a set of power transformers.
Recebido em 1º de março de 2018. Aprovado em 13 de abril de 2018. 1 A pesquisa em que se baseia este artigo foi realizada com recursos do CNPq. Resumo O artigo traz um retrato do uso de ferramentas de participação social e transparência da gestão nos websites de municípios brasileiros. Os dados foram cruzados com a variável Taxa de Urbanização (TU). Os procedimentos metodológicos abrangeram: (i) levantamento dos websites das prefeituras de municípios com mais de 20 mil habitantes; (ii) construção de plano amostral; e (iii) análise de 291 websites constantes da amostra. Foi aferida baixa correlação entre TU e o uso dessas ferramentas.
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