Time filter

Source Type

Cournon-d'Auvergne, France

Aguirre Martinez F.,Phimeca Engineering | Sallak M.,CNRS Heuristic and Diagnostic Methods for Complex Systems | Schon W.,CNRS Heuristic and Diagnostic Methods for Complex Systems
IEEE Transactions on Reliability | Year: 2015

We present an efficient method based on the inclusion-exclusion principle to compute the reliability of systems in the presence of epistemic uncertainty. A known drawback of belief functions and other imprecise probabilistic theories is that their manipulation is computationally demanding. Therefore, we investigate some conditions under which the measures of belief function theory are additive. If this property is met, the application of belief functions is more computationally efficient. It is shown that these conditions hold for minimal cuts and paths in reliability theory. A direct implication of this result is that the credal state (state of beliefs) about the failing (working) behavior of components does not affect the credal state about the working (failing) behavior of the system. This result is proven using a reliability analysis approach based on belief function theory. This result implies that the bounding interval of the system's reliability can be obtained with two simple calculations using methods similar to those of classical probabilistic approaches. A discussion about the applicability of the discussed theorems for non-coherent systems is also proposed. © 1963-2012 IEEE. Source

Dominguez N.,Airbus | Feuillard V.,Airbus | Jenson F.,CEA Saclay Nuclear Research Center | Willaume P.,Phimeca Engineering
AIP Conference Proceedings | Year: 2012

The concept of Probability of Detection (POD) is generally used to quantitatively assess performances and reliability of NDT operations for in-service operations related to damage tolerant designs. Application of the POD approach as a metric for manufacturing NDT assessment would also be relevant but the very expensive cost of such campaigns generally prevents us from doing so. However the increase in NDT simulation capability and maturity opens the field for POD demonstrations for manufacturing NDT with the help of simulation. This paper presents the example of an automated phased array ultrasonic testing procedure of Electron Beam Welding on rotative parts, as part of the PICASSO European project. POD is calculated by using the uncertainty propagation approach in CIVA. The peculiarity of uncertainties in automated NDT compared to in-service manual operations is discussed and raises questions on appropriate statistics to be used for this kind of data. Alternative estimation techniques like Box-Cox transform or quantile regression are proposed and evaluated. © 2012 American Institute of Physics. Source

Dubourg V.,Phimeca Engineering | Armand P.,CEA DAM Ile-de-France | Poulet D.,NUMTECH | Vendel F.,SILLAGES Environnement | And 4 more authors.
Proceedings of the 15th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, HARMO 2013 | Year: 2013

This paper describes a probabilistic risk assessment framework for helping stake-holders making the best decisions right after an accidental release of pollutant. The imprecise release conditions (weather and source) are modelled as random variables. Uncertainty propagation through a Lagrangian dispersion model is then proposed so as to build probabilistic risk maps that would eventually help the rescue teams to settle a lanyard around the critical zone The proposed methodology is applied to a virtual phosphine accidental release in an actual constructed area. Source

Argence S.,NUMTECH | Armand P.,CEA DAM Ile-de-France | Brocheton F.,NUMTECH | Yalamas T.,Phimeca Engineering | And 2 more authors.
HARMO 2011 - Proceedings of the 14th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes | Year: 2011

Long-term impact assessment (LIA) studies still rely on the use of deterministic dispersion modelling systems. Such a methodology does not allow quantifying uncertainties regarding the results of LIA studies while this kind of information is more and more asked by regulatory institutions. For three years, NUMTECH, CEA and PHIMECA have been collaborating to conceive an exhaustive tool dealing with the quantification of uncertainties related to LIA results. This tool is now functional and covers all aspects of a standard uncertainties study from the definition of input uncertainties to the statistical processing of concentration outputs (mean, confidence intervals, probabilities of threshold exceedance, etc.). The paper explains how this tool has been developed and gives examples of its use for a practical case study (with a unique source, a flat terrain and no plume rise) and a Gaussian plume dispersion model. Source

Decatoire R.,Phimeca Engineering | Decatoire R.,CNRS Foton Laboratory | Decatoire R.,University of Bordeaux 1 | De Larrard T.,INSA Toulouse | And 3 more authors.
7th European Workshop on Structural Health Monitoring, EWSHM 2014 - 2nd European Conference of the Prognostics and Health Management (PHM) Society | Year: 2014

In the scope of the inspection plan optimization of civil engineering structures subject to carbonation (carbon dioxyde penetration), several analytical models help to predict the degradation evolution. The degradation model used here is coming from the european project DuraCrete. This paper investigates its predictive capability, using the a priori of its inputs given in the litterature, but also after updating its predictions based on simulated measures with a finite element code. Copyright © Inria (2014). Source

Discover hidden collaborations