A two-step fusion process for multi-criteria decision applied to natural hazards in mountains

Mountain river torrents and snow avalanches generate human and material damages with dramatic consequences. Knowledge about natural phenomenona is often lacking and expertise is required for decision and risk management purposes using multi-disciplinary quantitative or qualitative approaches. Expertise is considered as a decision process based on imperfect information coming from more or less reliable and conflicting sources. A methodology mixing the Analytic Hierarchy Process (AHP), a multi-criteria aid-decision method, and information fusion using Belief Function Theory is described. Fuzzy Sets and Possibilities theories allow to transform quantitative and qualitative criteria into a common frame of discernment for decision in Dempster-Shafer Theory (DST ) and Dezert-Smarandache Theory (DSmT) contexts. Main issues consist in basic belief assignments elicitation, conflict identification and management, fusion rule choices, results validation but also in specific needs to make a difference between importance and reliability and uncertainty in the fusion process

Predicting Fluctuating Rates of Hospitalizations in Relation to Influenza Epidemics and Meteorological Factors

International audienceIntroductionIn France, rates of hospital admissions increase at the peaks of influenza epidemics. Predicting influenza-associated hospitalizations could help to anticipate increased hospital activity. The purpose of this study is to identify predictors of influenza epidemics through the analysis of meteorological data, and medical data provided by general practitioners.MethodsHistorical data were collected from Meteo France, the Sentinelles network and hospitals’ information systems for a period of 8 years (2007–2015). First, connections between meteorological and medical data were estimated with the Pearson correlation coefficient, Principal component analysis and classification methods (Ward and k-means). Epidemic states of tested weeks were then predicted for each week during a one-year period using linear discriminant analysis. Finally, transition probabilities between epidemic states were calculated with the Markov Chain method.ResultsHigh correlations were found between influenza-associated hospitalizations and the variables: Sentinelles and emergency department admissions, and anti-correlations were found between hospitalizations and each of meteorological factors applying a time lag of: -13, -12 and -32 days respectively for temperature, absolute humidity and solar radiation. Epidemic weeks were predicted accurately with the linear discriminant analysis method; however there were many misclassifications about intermediate and non-epidemic weeks. Transition probability to an epidemic state was 100% when meteorological variables were below: 2°C, 4 g/m3 and 32 W/m2, respectively for temperature, absolute humidity and solar radiation. This probability was 0% when meteorological variables were above: 6°C, 5.8g/m3 and 74W/m2.ConclusionThese results confirm a good correlation between influenza-associated hospitalizations, meteorological factors and general practitioner’s activity, the latter being the strongest predictor of hospital activity

AHP and uncertainty theories for decision making using the ER-MCDA methodology

International audienceIn this paper, we present the ER-MCDA methodology for multi-criteria decision-making based on imperfect information coming from more or less reliable and conflicting sources. The Analytic Hierarchy Process (AHP), Fuzzy Sets, Possibility and Belief Functions theories are combined to take a decision based on imprecise and uncertain evaluations of quantitative, qualitative criteria. Classical aggregation of criteria is replaced by a two-step fusion process using advanced fusion rules based on the Dezert-Smarandache Theory (DSmT) that allows to make a difference between importance, reliability and uncertainty of information sources and contents

Predicting Ozone Peaks : A combined CBR and cell mapping approach

http://www.iemss.org/iemss2002/proceedings/pdf/volume%20tre/139_pearson.pdfInternational audienceIn this paper we present a new approach for predicting ozone peaks when monitoring atmospheric pollution. Our main idea is that atmospheric pollution is closely monitored and over the past 5 to 10 years we have built up fairly extensive databases concerning it. Thus, rather than looking for a physical model in the first instance, maybe we should look for patterns and repeatability in the historical data. The approach presented is a hybrid one based on case based reasoning and cell mapping. Essentially, we forget all about a model in the first instance and simply search historical data to see if we can construct cases. We then extend this idea to include notions from cell mapping to see if we can build a cell map from the cases. The method is applied to real data coming from the Rhône-Alpes region of France

Approche spatio-temporelle et modélisation pour l'identification et la quantification des échanges hydrauliques entre une rivière et sa nappe phréatique alluviale. Application au fleuve Rhône.

International audienceLa Directive Cadre sur l'Eau (DCE) impose à l'horizon 2015 de prendre en compte les masses d'eau souterraines pour la durabilité et la disponibilité des ressources en eau. Elle requiert une prise en considération des relations entre les masses d'eau, notamment superficielles et souterraines. Dans ce cadre la dynamique des échanges entre eaux de surface et eaux souterraines est étudiée, pour des aquifères alluviaux et à l'aide de trois types d'outils : les modèles déterministes, les modèles boîtes noires et les modèles d'analyse multi-variée spatiale. La complémentarité des résultats obtenus avec ces méthodes est analysée sur un secteur à forts enjeux socio-économiques, concernant l'usage de la ressource en eau, autour de Péage-De-Roussillon. Les analyses corrélatoires et spectrales, sur les signaux de hauteurs de nappes et de rivières, ont permis de mettre en évidence des zones de comportements différents au sein de la nappe, ainsi que l'importance globale des interactions entre la nappe et la rivière. Un premier modèle hydrodynamique de la nappe a parallèlement pu être établi en intégrant les résultats d'un modèle d'écoulements surfaciques. Ces travaux s'insèrent dans le projet " Echanges nappes/Rhône " de l'accord-cadre entre la ZABR et l'agence de l'eau Rhône-Méditerranée-Corse. // The European framework directive on water requires by 2015 to take into account the groundwater bodies for durability and availability of water resources. It requires taking into consideration the relationship between water bodies, especially surface water and groundwater. In this frame, the exchange dynamics between surface water and groundwater is studied for alluvial aquifers by means of three types of tools: deterministic models, black box models and models of mutivariate spatial analysis. The complementarity of the results hence obtained is discussed on an area with high socio-economic stakes concerning the use of water resources around Péage-de-Roussillon (France, Rhône river). Correlative and spectral analysis, on groundwater and surface water head signals, allowed defining areas of different hydraulic behaviors within the aquifer as well as the importance of the river-aquifer interactions. A groundwater hydrodynamic model has been established by integrating the results of a surface water model. These works are part of the "Rhone aquifer exchanges" project of the framework agreement between the ZABR and the Rhône-Méditerranée-Corse water agency

Applying new uncertainty related theories and multicriteria decision analysis methods to snow avalanche risk management

International audienceMaking the best decision in the event of a snow avalanche encounters problems in the assessment and management process because of the lack of information and knowledge on natural phenomena and the heterogeneity and reliability of the information sources available (historical data, field measurements, and expert assessments). One major goal today is therefore to aid decision making by improving the quality, quantity, and reliability of the available information. This article presents a new method called evidential reasoning and multicriteria decision analysis (ER-MCDA) to help decision making by considering information imperfections arising from several more or less reliable and possibly conflicting sources of information. First, the principles of the existing methods are reviewed. Classical methods of multicriteria decision making and existing theories attempting to represent and propagate information imperfections are described. In a second point, we describe the principle of the ER-MCDA method combining multicriteria decision analysis (MCDA) to model the decision-making process and fuzzy sets theory, possibility theory, and evidence theory to represent, fuse and propagate information imperfections. Experts, considered more or less reliable, provide imprecise and uncertain evaluations of quantitative and qualitative criteria that are combined through information fusion. The method is applied to a simplified version of an existing system aiming to evaluate the sensitivity of avalanche sites. This new method makes it possible to consider both the importance of the information available and reliability in the decision process. It also contributes to improving traceability. Other developments designed to handle other assessment problems such as avalanche triggering conditions or data quality are in progress

Intégrer une dimension écologique et paysagère dans la planification territoriale - Méthode et questionnement à propos de la démarche Infrastructures Vertes et Bleues (IVB) dans les SCoT de la Loire (France).

International audienceLes objectifs de l'article se situent à deux niveaux. Il s'agira d'une part d'analyser le plus objectivement possible la démarche IVB, la manière dont elle s'est construite, les choix méthodologiques et techniques et leurs raisons, le rôle des différents concepteurs et utilisateurs, les contraintes, limites et potentialités d'amélioration de la méthode. Mais nous rendrons compte aussi des questionnements liés à la conception et au fonctionnement de l'atelier participatif conçu pour élaborer et tester des propositions méthodologiques

Parameter Optimization in Groundwater using Proper Orthogonal Decomposition as a Reduced Modeling Technique

http://www.epsmso.gr/all_conf_index/abstracts/ic-scce_2012_abs054.pdfInternational audienceThis paper deals with different approaches of applying Proper Orthogonal Decomposition in the field of groundwater flow, specifically the Richards equation, which is a convection-diffusion partial differential equation governing the behaviour of unsaturated fluid flow through a porous medium. The motivation for this research is the need to reduce computational complexity in inverse modelling studies, where a significant number of simulations are needed to determine suitable model parameters. Three different methods of implementing Proper Orthogonal Decomposition are explored. The first method is the Petrov-Galerkin method, a method well suited to speeding up linear problems. The second method is a "Hybrid" method, and proposes a linearization of all non-linear functions, building upon the Petrov-Galerkin approach. As such, it is suitable for use in the non-saturated groundwater zone. The third method combines the use of kriging and Proper Orthogonal to create a non-intrusive model for comparison purposes. With these three methods, the suitability of Proper Orthogonal as a reduced modelling method for unsaturated groundwater flow is shown

Environmental data treatment to extract the Knowledge needed for “advanced decision-making”- A «mixed approach » to modelling and to simulating “natural or non natural” process effects in the Environmental Sciences : from GIS to Data Mining through Determinist Modelling

International audienc

Evaluation du Risque Sanitaire lié aux émissions de Chrome VI - Entreprise EUROTHAL SA (Saint-Étienne)

25 p. confidentiel.Rapport final du contrat EUROTHAL - EMS