Univariate Lévy processes have become quite common in the reliability literature for modelling accumulative deterioration. In case of correlated deterioration indicators, several possibilities have been suggested for modelling their dependence. The point of this study is the analysis and comparison of three different dependence models considered in the most recent literature: 1. Use of a...
In the context of semiconductor reliability, predictive maintenance and calculation of residual useful life are important topics under the greater umbrella of prognostics and health management.
Especially in automotive applications, with higher expected usage times of self-driving autonomous vehicles, it becomes more and more important to recognize degradation processes early, so that...
Let $\boldsymbol{X}=(X_t)_{t\ge 0}$ be a process behaving as a general increasing Lévy process (subordinator) prior to hitting a given unknown level $m_0$, then behaving as another different subordinator once this threshold is crossed. We address the detection of this unknown threshold $m_0\in [0,+\infty]$ from an observed trajectory of the process. These kind of model and issue are...
Optimisation of maintenance policies for items with their repair processes modelled by the geometric process (GP) has received a good amount of attention. The extended Poisson process (EPP), one of the extensions of the GP, can be used to model the repair process with its times-between-failures possessing a non-monotonic trend. A central issue in the applications of the EPPs in maintenance...
Models that describe the deterioration processes of the components are key to determining the lifetime of a system and play a fundamental role in predicting the system reliability and planning the system maintenance. In most systems there is heterogeneity among the degradation paths of the units. This variability is usually introduced in the model through random effects, that is, considering...
In this paper, a multi-component series system is considered which is periodically inspected and at inspection times the failed components are replaced by a new one. Therefore, this maintenance action is perfect corrective maintenance for the failed component, and it can be considered as imperfect corrective maintenance for the system. The inspection interval is considered as a decision...
A Reliability degradation model was developed in a project, which involved LCD TV screens installed on railway. One critical item in the project was an LED strip.
Accelerated Life tests data are the data source for the determination of LED Reliability. The expected life of LEDs being about 10-15 years - testing them until death is not practical.
Luminosity (vs time measurements provided...
A Digital Twin (DT) is a new and powerful concept that maps a physical structure operating in a specific context to the digital space. The development and deployment of a DT improves forecasting prognostic performance and decision support for operators and managers. , DT have been introduced in various industries across a range of application areas including design, manufacturing and...
Abstract
This work is motivated by the non-documented, practical learnings gained by a predictive maintenance (PdM) development team in the Danish energy company Ørsted. The team implements PdM solutions for power plant machinery to monitor for faults in the making. Their learnings support the hypothesis that there are not significant enough benefits to be gained from using overly...
Battery prognostics and health management has recently become a very important and strategic topic specially with the rise of electric vehicles and electric mobility in general, which is seen as a key tool to reduce the impact of global warming. In order for battery health management to be viable, it is necessary to quantify and understand battery state of health (SOH) and its degradation...
Along with the shortening of production period, manufacturing industry utilizes an accelerated degradation test (ADT) to estimate the reliability of newly developed products as quickly as possible. In ADT, the stress factor which is related to the failure mechanisms is imposed to cause the failure of products faster than those under normal use condition. By increasing the degree of stress such...
A system subject to degradation is considered. The degradation is modelled by a gamma process. A condition-based maintenance policy with perfect corrective and an imperfect preventive actions is proposed. The maintenance cost is derived considering a Markov-renewal process. The statistical inference of the degradation and maintenance parameters by the maximum likelihood method is proposed. A...
In this article, technological or industrial equipment that are subject to degradation are considered. These units undergo maintenance actions, which reduce their degradation level.
The paper considers a degradation model with imperfect maintenance effect. The underlying degradation process is a Wiener process with drift. The maintenance effects are described with an Arithmetic Reduction of...
Degradation models are more and more studied and used in practice. Most of these models are based on Lévy processes. For such models, estimation methods have been proposed. These models are also considered for developing complex and efficient maintenance policies. However, a main issue remains: goodness-of-fit (GoF) test for these models. In this talk, we propose a GoF test for the homogeneous...
Degradation modeling is an effective way for the reliability analysis of complex systems. For highly reliable systems, in which their failure is hard to observe, degradation measurements often provide more information than failure time to improve system reliability (Meeker and Escobar 2014). The degradation can be viewed as damage to a system that accumulates over time and eventually leads to...
Consider a fixed number of clustered areas identified by their geographical coordinate that monitored for the occurrences of an event such as pandemic, epidemic, migration to name a few. Data collected on units at all areas include time varying covariates and environmental factors. The collected data is considered pairwise to account for spatial correlation between all pair of areas. The...
A phase-type distribution can be defined to be the distribution of time to absorption for an absorbing finite state Markov chain in continuous time. Phase-type distributions have received much attention in applied probability, in particular in queuing theory, generalizing the Erlang distribution. Among other applications, they have for a long time been used in reliability and survival...
Jerome de Reffye
Engineering Degrees from Gustave Eiffel University ( ESIEE )
and Pierre et Marie Curie University ( Paris VI )
PhD in applied mathematics and theoretical physics
from Pierre et Marie Curie University
On opposite way of empirical approachs we develop an analytic method in Reliability - Maintainability - Availability - Safety (RAMS) area which led to the RELSYS model,...
Across industries, the growing dependence on battery pack energy storage has underscored the importance of battery management systems (BMS) whose role is to monitor battery state, ensure safe operation and maximize performance. For example, the BMS helps avoid overcharging and over discharging, it manages the temperature of the battery and so on, and it does so by collecting information from...
Through incorporating a bivariate state process, this paper explores an approach to the stochastic modeling of MRL for a failure-prone parallel system operating in a random environment. The bivariate state-dependent MRL (BSDMRL) model outperforms the ordinary MRL and other state-dependent MRL models in the actual circumstance that it incorporates not only the age factor, but also two basic...
According to the failure threshold model, degrading units are typically assumed to fail when their degradation level exceeds an assigned threshold limit. Consequently, the reliability function of these units is defined in terms of the first passage time distribution of their degradation process to the assigned threshold.
This degradation process-based approach to reliability modelling...
One of the most popular ways to model an impact of a random environment on system’s performance characteristics is via the external shocks that either cause certain damages or immediately result in failures. There is vast literature on this topic with respect to the relevant theoretical properties of the corresponding lifetime models as well as to the various practical applications. One of the...
In reliability theory, k-out-of-n systems play an important role as these are the basic structures of many technical systems used in real-life. While modeling these systems, we most often assumed that the failure of one component does not have any impact on the performance of the remaining surviving components. This indeed oversimplifies the modelling of such systems. Sequential order...