16,731 research outputs found
Managing Well Integrity using Reliability Based Models
Imperial Users onl
Development and implementation of preventive-maintenance practices in Nigerian industries.
A methodology for the development of PM using the modern approaches of FMEA, root-cause analysis, and fault-tree analysis is presented. Applying PM leads to a cost reduction in maintenance and less overall energy expenditure. Implementation of PM is preferable to the present reactive maintenance procedures (still prevalent in Nigeria
Maintenance optimization of a production system with buffercapacity
Marketing;Optimization;produktieleer/ produktieplanning
Reliability applied to maintenance
The thesis covers studies conducted during 1976-79 under a
Science Research Council contract to examine the uses of reliability
information in decision-making in maintenance in the process industries.
After a discussion of the ideal data system, four practical studies
of process plants are described involving both Pareto and distribution
analysis. In two of these studies the maintenance policy was changed
and the effect on failure modes and frequency observed. Hyper-exponentially
distributed failure intervals were found to be common and were explained
after observation of maintenance work practices and development of
theory as being due to poor workmanship and parts. The fallacy that
constant failure rate necessarily implies the optimality of maintenance
only at failure is discussed.
Two models for the optimisation of inspection intervals are
developed; both assume items give detectable warning of impending failure.
The first is based upon constant risk of failure between successive
inspections 'and Weibull base failure distribution~ Results show that
an inspection/on-condition maintenance regime can be cost effective
even when the failure rate is falling and may be better than periodiC
renewals for an increasing failure situation. The second model is first-order Markov. Transition rate matrices are developed and solved
to compare continuous monitoring with inspections/on-condition
maintenance an a cost basis. The models incorporate planning delay
in starting maintenance after impending failure is detected.
The relationships between plant output and maintenance policy
as affected by the presence of redundancy and/or storage between stages
are examined, mainly through the literature but with some original
theoretical proposals.
It is concluded that reliability techniques have many applications
in the improvement of plant maintenance policy. Techniques abound,
but few firms are willing to take the step of faith to set up, even
temporarily, the data-collection facilities required to apply them.
There are over 350 references, many of which are reviewed in the
text, divided into chapter-related sectionso
Appendices include a review of Reliability Engineering Theory,
based on the author's draft for BS 5760(2) a discussion of the 'bath-tub
curves' applicability to maintained systems and the theory connecting
hyper-exponentially distributed failures with poor maintenance
practices
Modelo de apoio à decisão para a manutenção condicionada de equipamentos produtivos
Doctoral Thesis for PhD degree in Industrial and Systems EngineeringIntroduction: This thesis describes a methodology to combine Bayesian control chart
and CBM (Condition-Based Maintenance) for developing a new integrated model. In
maintenance management, it is a challenging task for decision-maker to conduct an
appropriate and accurate decision. Proper and well-performed CBM models are
beneficial for maintenance decision making. The integration of Bayesian control chart
and CBM is considered as an intelligent model and a suitable strategy for forecasting
items failures as well as allow providing an effectiveness maintenance cost. CBM
models provides lower inventory costs for spare parts, reduces unplanned outage, and
minimize the risk of catastrophic failure, avoiding high penalties associated with losses
of production or delays, increasing availability. However, CBM models need new
aspects and the integration of new type of information in maintenance modeling that can
improve the results. Objective: The thesis aims to develop a new methodology based on
Bayesian control chart for predicting failures of item incorporating simultaneously two
types of data: key quality control measurement and equipment condition parameters. In
other words, the project research questions are directed to give the lower maintenance
costs for real process control. Method: The mathematical approach carried out in this
study for developing an optimal Condition Based Maintenance policy included the
Weibull analysis for verifying the Markov property, Delay time concept used for
deterioration modeling and PSO and Monte Carlo simulation. These models are used for
finding the upper control limit and the interval monitoring that minimizes the
(maintenance) cost function. Result: The main contribution of this thesis is that the
proposed model performs better than previous models in which the hypothesis of using
simultaneously data about condition equipment parameters and quality control
measurements improve the effectiveness of integrated model Bayesian control chart for
Condition Based Maintenance.Introdução: Esta tese descreve uma metodologia para combinar Bayesian control chart
e CBM (Condition- Based Maintenance) para desenvolver um novo modelo integrado.
Na gestão da manutenção, é importante que o decisor possa tomar decisões apropriadas
e corretas. Modelos CBM bem concebidos serão muito benéficos nas tomadas de
decisão sobre manutenção. A integração dos gráficos de controlo Bayesian e CBM é
considerada um modelo inteligente e uma estratégica adequada para prever as falhas de
componentes bem como produzir um controlo de custos de manutenção. Os modelos
CBM conseguem definir custos de inventário mais baixos para as partes de substituição,
reduzem interrupções não planeadas e minimizam o risco de falhas catastróficas,
evitando elevadas penalizações associadas a perdas de produção ou atrasos, aumentando
a disponibilidade. Contudo, os modelos CBM precisam de alterações e a integração de
novos tipos de informação na modelação de manutenção que permitam melhorar os
resultados.Objetivos: Esta tese pretende desenvolver uma nova metodologia baseada
Bayesian control chart para prever as falhas de partes, incorporando dois tipos de
dados: medições-chave de controlo de qualidade e parâmetros de condição do
equipamento. Por outras palavras, as questões de investigação são direcionadas para
diminuir custos de manutenção no processo de controlo.Métodos: Os modelos
matemáticos implementados neste estudo para desenvolver uma política ótima de CBM
incluíram a análise de Weibull para verificação da propriedade de Markov, conceito de
atraso de tempo para a modelação da deterioração, PSO e simulação de Monte Carlo.
Estes modelos são usados para encontrar o limite superior de controlo e o intervalo de
monotorização para minimizar a função de custos de manutenção.Resultados: A
principal contribuição desta tese é que o modelo proposto melhora os resultados dos
modelos anteriores, baseando-se na hipótese de que, usando simultaneamente dados dos
parâmetros dos equipamentos e medições de controlo de qualidade. Assim obtém-se
uma melhoria a eficácia do modelo integrado de Bayesian control chart para a
manutenção condicionada
- …