Search results for "bayesian approach"
showing 9 items of 9 documents
Epidemiology of Multiple Sclerosis en France
2012
In Europe, France is located between high and low risk areas of Multiple Sclerosis (MS). We estimated the national prevalence of MS in France on 31st October 2004 and the incidence between 2000 and 2007 based on data from the ‘Caisse Nationale d’Assurance Maladie des Travailleurs Salariés’ which insures 87% of the population. MS like other chronic diseases is one of the 30 long-term illnesses (Affections de Longue Durée, ALD). We analysed geographic variations in the prevalence and incidence of MS in France using the Bayesian approach.Total MS prevalence in France standardised for age was 94.7 per 100,000; 130.5 in women; 54.8 in men. The notification rate for MS (2000-2007) after age-stand…
Strategies for Improving Optimal Positioning of Quality Sensors in Urban Drainage Systems for Non-Conservative Contaminants
2021
In the urban drainage sector, the problem of polluting discharges in sewers may act on the proper functioning of the sewer system, on the wastewater treatment plant reliability and on the receiving water body preservation. Therefore, the implementation of a chemical monitoring network is necessary to promptly detect and contain the event of contamination. Sensor location is usually an optimization exercise that is based on probabilistic or black-box methods and their efficiency is usually dependent on the initial assumption made on possible eligibility of nodes to become a monitoring point. It is a common practice to establish an initial non-informative assumption by considering all network…
A Bayesian approach for predictive maintenance policy with imperfect monitoring
2009
In the traditional preventive maintenance policy, the periodic maintenance activities are scheduled on the basis of the a-priori information about the failure behaviour of the population which the component belongs to, by assuming a probability distribution function and by estimating the involved statistical parameters. On the contrary, with the predictive approach, the maintenance activity is scheduled on the basis of the real degradation level of the component. So, it is possible to reduce the failure probability and, at the same time, to use the component for almost all its useful life. For this reason, the predictive maintenance policy makes possible the reduction of the maintenance cos…
New insight into the colonization processes of common voles: inferences from molecular and fossil evidence.
2008
Biologie et Gestion des Populations, Campus International de Baillarguet, Montferrier/Lez, FranceElucidating the colonization processes associated with Quaternary climatic cycles is important in order to understand the distribution of biodiversity and the evolutionary potential of temperate plant and animal species. In Europe, general evolutionary scenarios have been defined from genetic evidence. Recently, these scenarios have been challenged with genetic as well as fossil data. The origins of the modern distributions of most temperate plant and animal species could predate the Last Glacial Maximum. The glacial survival of such populations may have occurred in either southern (Mediterranea…
Production and Efficiency in 21 Industrialized Countries from 1966 to 2007 to Analyse the Italy’s Decline: Application of a Stochastic Frontier Model…
2008
This paper uses a stochastic frontier production model to estimate the technical efficiency of 21 nations among the more industrialized countries in the world for the wide period from 1966 to 2007. A Cobb-Douglas with labour and capital as inputs, GDP as output and efficiency with exponential distribution appears to work good from a statistical point of view. This model is used to estimate in a bayesian approach the efficiency score of these 21 countries. The bayesian way, applied via Gibbs sampling, is here useful to avoid problems about the small number of observations. So, each efficiency score is obtained as mean of 10,000 draws. The results underline a general and progressive efficienc…
On the measured lifetime of light hypernuclei 3ΛH and 4ΛH
2014
A statistical combination of the experimental lifetime estimations available in the literatures is performed for 3 Λ H and 4 Λ H, including several recent measurements. The combined average values of the lifetime for 3 Λ H and 4 Λ H are respectively 216−16+19 ps and 192−18+20 ps with a reduced χ2 of 0.89 and 0.48. A new insight into the lifetime estimation of the HypHI Phase 0 experiment by a Bayesian approach is also presented. In this approach, several different prior distributions including the combination of previous lifetime data and a Jeffrey prior are used. The principal mode and the smallest credible interval at 68% of the posterior distribution, given by the prior belief of the pre…
A predictive maintenance policy with imperfect monitoring
2010
For many systems,failure is a very dangerous or costly event. To reduce the occurrence of this event,it is necessary to implement a preventive maintenance policy to replace the critical elements before failure.Since elements do not often exhibit incipient faults, they are replaced before a complete exploiting of their useful life.To conjugate the objective of exploiting elements for almost all their useful life with the objective to avoid failure,condition based and,more recently,predictive maintenance policies have been proposed.This paper deals with this topic and proposes a procedure for the computation of the maintenance time that minimizes the global maintenance cost.By adopting a stoc…
Bayesian approach for uncertainty quantification in water quality modelling: The influence of prior distribution
2010
Summary Mathematical models are of common use in urban drainage, and they are increasingly being applied to support decisions about design and alternative management strategies. In this context, uncertainty analysis is of undoubted necessity in urban drainage modelling. However, despite the crucial role played by uncertainty quantification, several methodological aspects need to be clarified and deserve further investigation, especially in water quality modelling. One of them is related to the “a priori” hypotheses involved in the uncertainty analysis. Such hypotheses are usually condensed in “a priori” distributions assessing the most likely values for model parameters. This paper explores…
Particle identification in ALICE: a Bayesian approach
2016
We present a Bayesian approach to particle identification (PID) within the ALICE experiment. The aim is to more effectively combine the particle identification capabilities of its various detectors. After a brief explanation of the adopted methodology and formalism, the performance of the Bayesian PID approach for charged pions, kaons and protons in the central barrel of ALICE is studied. PID is performed via measurements of specific energy loss ($\mathrm{d}E/\mathrm{d}x$) and time-of-flight. PID efficiencies and misidentification probabilities are extracted and compared with Monte Carlo simulations using high-purity samples of identified particles in the decay channels ${\rm K}^0_S \righta…