Recursos de colección

Repositório Comum (25.504 recursos)

É um repositório para instituições de ensino e investigação produtoras de literatura científica cuja dimensão ainda não justifica a criação de um repositório próprio. Permite integrar instituições, grupos ou indivíduos na infra-estrutura do projecto, nomeadamente através das pesquisas do Portal RCAAP e da B-On.

Mostrando recursos 1 - 3 de 3

  1. Implementation of MEWMA Control Chart in Equipment Condition Monitoring

    Lampreia, Suzana Paula Gomes Fernando da SIlva; Vairinhos, V.
    The progressive degradation of presently operating electro-mechanical systems is a certain future fact. To minimize losses, maintenance costs and eventual replacements, condition monitoring should be applied to critical equipment (Condition Based Maintenance – CBM). The state of equipment can be predicted at any moment using statistical methods to analyze condition monitoring data. In this paper, collected data are vibration values, obtained at p points (p = 4 for instance) of an experimental equipment, forming p variables. When independence condition does not hold, it is suggested modeling data with Auto-Regressive Integrated Moving Average (ARIMA) models, and using the residues of the estimated model for Phase I. In Phase...
    - 17-feb-2017

  2. Opportunistic Maintenance Based on CUSUM Control Charts

    Lampreia, Suzana Paula Gomes Fernando da Silva; Vairinhos, V.; Lobo, V.; Parreira, R.
    The use of a Ship Maintenance Management System is fundamental for the good performance of equipments and the entire platform. Over the systematic maintenance, the opportunistic maintenance is a concept that aims to minimize outages and costs preventing undesirable failures. To implement this kind of maintenance statistical methodologies must be used. The Cumulative Sum charts have a very good performance applied to processes control in quality control. We proposed the use of Modified Cumulative Sum control charts to equipment maintenance.The data under study are observations of cooling water and oil temperatures from a diesel generator. In the first phase, we will apply...
    - 17-feb-2017

  3. Control Charts Limits Flexibility Based on the Equipment Conditions

    Lampreia, Suzana Paula Gomes Fernando da Silva; Vairinhos, V.; Lobo, V.; Parreira, R.
    Condition Based Maintenance became an important development in industrial and transport equipment maintenance efforts. Many statistical methodologies have been applied in this area. These methodologies are usually applied off-line: after the data is collected. We propose an online, real-time condition monitoring system based on a modified control chart, applied to engine parameters. These charts should be flexible enough and its control limits should reflect the equipment state, the manufacturer specifications and onboard meteorological conditions. In this study we will develop a methodology to specify flexible chart control limits. The experimental equipment is a combined diesel or gas propulsion system. Two phases...
    - 17-feb-2017

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