Generic approach of the uncertainty management in multisensor fusion processes

The uncertainty management in multisensor systems is considered in the federative framework of the theory of evidence. A basic operator, named extension, is elaborated. It provides a general formulation of the different operators that constitute a complete and coherent processing of multiple uncertain observations, from their modeling up to the required decision making. This formulation allows to reason with believes individually expressed on heterogeneous frames of discernment, without using a common one. The particular conditions that lead to the traditional operators are specified, and the implementation of the new generic operator is described. A few examples illustrate a suitable management of uncertainty processing.Le problème de la gestion de l’incertain au sein des systèmes multisenseurs est abordé dans le cadre fédérateur de la théorie de l’évidence. Un opérateur de base appelé extension est élaboré, dont on montre qu’il permet de générer, sous une forme générale, les différents opérateurs utiles à la constitution d’une chaîne complète et cohérente de traitement d’observations incertaines multiples, depuis leur modélisation jusqu’à la prise de décision exigée. Cette formulation permet, en particulier, de raisonner sur des croyances exprimées individuellement dans des référentiels hétérogènes, sans avoir à les ramener dans un cadre de discernement commun. Les conditions particulières qui permettent de retrouver les opérateurs traditionnels sont précisées, et la mise en oeuvre pratique de l’opérateur générique proposé est décrite. Quelques exemples illustrent le bon usage qui peut ainsi être fait du traitement de l’incertain

Theory of evidence and non-exhaustive frames of discernment

To represent a source's knowledge, all the existing theories work on a set of hypotheses of interest on which different treatment s can be applied . Called the frame of discernment in the theory of evidence, it must have the property of exhaustivity, which mean s that one of the hypotheses is the solution of the problem . Nevertheless, in some practical cases, this doesn't occur . Consequently, the knowledge modelised in such a frame is incomplete because some hypotheses are not considered . The last literature doesn't deal with this situation . This article gives some solutions in the theory of evidence's formalism, which appears the most appropriat e in this case . A practical application could be for example a supervised classification problem of objects, when the learning set i s incomplete, due to a lack of learning data for one or several objects .Pour modéliser la connaissance d'une source d'information, les différentes théories existantes ont toutes pour principe de travailler sur un référentiel de base, composé d'hypothèses d'intérêt sur lesquelles différents traitements peuvent porter par la suite. En général, ce référentiel est exhaustif signifiant que la solution se trouve parmi toutes les hypothèses considérées. Néanmoins, dans la pratique, il existe des cas où il ne l'est pas; la connaissance modélisée sur un tel référentiel est alors incomplète car elle ne permet pas de prendre en compte certaines hypothèses. Ceci forme un problème peu abordé dans la littérature. Cet article propose donc différentes solutions pour le traiter, dans le formalisme de la théorie de l'évidence qui est a priori la plus adaptée. Un cadre applicatif intéressant peut concerner, par exemple, un problème de classification supervisée d'objets dans le cas d'une base d'apprentissage incomplète, lorsque certaines données caractéristiques d'un objet ne sont pas disponibles lors de l'apprentissage

Simple scoring system to predict in-hospital mortality after surgery for infective endocarditis

BACKGROUND: Aspecific scoring systems are used to predict the risk of death postsurgery in patients with infective endocarditis (IE). The purpose of the present study was both to analyze the risk factors for in-hospital death, which complicates surgery for IE, and to create a mortality risk score based on the results of this analysis. METHODS AND RESULTS: Outcomes of 361 consecutive patients (mean age, 59.1\ub115.4 years) who had undergone surgery for IE in 8 European centers of cardiac surgery were recorded prospectively, and a risk factor analysis (multivariable logistic regression) for in-hospital death was performed. The discriminatory power of a new predictive scoring system was assessed with the receiver operating characteristic curve analysis. Score validation procedures were carried out. Fifty-six (15.5%) patients died postsurgery. BMI >27 kg/m2 (odds ratio [OR], 1.79; P=0.049), estimated glomerular filtration rate 55 mm Hg (OR, 1.78; P=0.032), and critical state (OR, 2.37; P=0.017) were independent predictors of in-hospital death. A scoring system was devised to predict in-hospital death postsurgery for IE (area under the receiver operating characteristic curve, 0.780; 95% CI, 0.734-0.822). The score performed better than 5 of 6 scoring systems for in-hospital death after cardiac surgery that were considered. CONCLUSIONS: A simple scoring system based on risk factors for in-hospital death was specifically created to predict mortality risk postsurgery in patients with IE

Time-lapse gravity monitoring of CO2 migration based on numerical modeling of a faulted storage complex

In this study, the performance of both surface and borehole time-lapse gravity monitoring to detect CO leakage from a carbon storage site is evaluated. Several hypothetical scenarios of CO migration in a leaky fault, and thief zones at different depths at the Kimberlina site (California, USA) constitute the basis of the approach. The CO displacement is simulated using the TOUGH2 simulator applied to a detailed geological model of the site. The gravity responses to these CO plumes are simulated using forward modeling with sensors at ground surface and in vertical boreholes. Results of inversion on one scenario are also presented. The surface-based gravity responses obtained for the different leakage scenarios demonstrate that leakage can be detected at the surface in all the scenarios but the time to detection is highly variable (10–40 years) and dependent on the detection threshold considered. Borehole measurements of the vertical component of gravity provide excellent constraints in depth when they are located in proximity of the density anomaly associated with the presence of CO , thus discriminating multiple leaks in different thief zones. Joint inversion of surface and borehole data can bring valuable information of the occurrence of leakages and their importance by providing a reasonable estimate of mass of displaced fluids. This study demonstrates the importance of combining multiphase flow simulations with gravity modeling in order to define if and when gravity monitoring would be applicable at a given storage site. 2 2 2 2

Multisensor data fusion in situation assessment processes

Communication to : ECSQUARU/FAPR'97, Seminaris - Bad Honnef (Germany), June 9-12, 1997SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1997 n.34 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Spectroscopic factors optimization in electrothermal atomic absorption spectrometry via an optimal experimental design matrix

International audienceA method, fast and simple to carry out, is proposed to optimize the instrumental spectroscopic parameters, such as bandpass, lamp current and monochromator slit height in electrothermal atomic absorption spectrometry. It is based on the monitoring of the detection limit estimation (DLE) variation by using a 'D-optimal' experimental design. This method is tested on Cd, Mn, Cu and Sn. In comparison with the default operating conditions, the limits of detection are systematically improved

Formulation et traitement de l'incertain en analyse multi-senseurs

Communication to : conference invitee au 14"eme colloque GRETSI sur le traitement du signal et des images, Juan-les-Pins (France), 13-16 septembre 1993Available at INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1993 n.162 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Pixel fusion : contribution of contextual physical data for the 'a priori' database construction

Communication to : 1st international symposium on physics in signal and image processing (PSIP'99), Versailles (france), January 17-21, 1999Available from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1999 n.20 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc