Search results for "STATISTICS"

Test methodologies for the unitary root

1998

This paper provides a critical survey on unit root testing procedures frequently used in empirical literature. The importance of the hypothesis of linearity of the deterministic component is stressed because its misspecification may result in the false conclusion that the time series has a unit root. Testing strategies elaborated by Dickey, Bell and Miller (1986), Perron (1988) and Dolado, Jenkinson and Sosvilla-Rivero (1990) are compared and their limit is evaluated. An empirical testing strategy is then proposed and applied to the analysis of the nonstationarity exhibited by real GDP in France. We show that it is possible to find some flexible specifications that enable us to reject the u…

Numerical Optimization of Liner Impedance in Acoustic Duct

2020

Abstract The SALUTE project aims at evaluating performance of metacomposites for acoustic smart lining in grazing turbulent flow. Theoretical and numerical investigations are carried out for designing innovative specimen. A specific focus is placed in the realization of prototypes for evaluating the metacomposite liner performances in 2D and 3D liners, its process complexity and robustness. The insight gain in this project is new tools for obtaining innovative samples; the acoustical experimental tests demonstrate efficiency and robustness of such technology for controlling UHBR noise emission. This paper is focused on parametric study based on the maximization of the absorption coefficient…

Gas sensors arrays (electronic noses) : a study about the speed/accuracy ratio

2000

Abstract New Fingerprint Mass Spectra (FMS) systems claim for a higher precision, a reduced analysis time, and a lower drift, compared with Gas Sensors Arrays ‘Electronic Noses’. We demonstrated in this study that metal oxide gas sensors may have highly improved performances for both accuracy and run time, when used in optimum conditions. The different noise components were quantified referring to popular words (equivalent of ethanol concentration) using the transfer function of the sensor. It was pointed out that sample surrounding greatly affects the noise level, and that the signal-to-noise ratio may be dramatically increased, reducing the distortion generally assessed between sensor and…

Electronic noses : specify or disappear

2000

Abstract When the quality control is achieved by using GC or GC/MS, the apparatus must comply with the applicable norms, but what about “electronic noses”? End users demand for formal specifications for selectivity, sensitivity, repeatability and sample throughput. The behavioural modelling of electronic olfactometers may provide specifications for these required parameters. This will allow both the measure itself, and evaluate the influence of the experimental errors on the sample classification. Users may expect to find a methodology allowing the performances of systems to be checked before any final decision and during routine use. We have demonstrated that the system sensitivity and log…

A multiple-response chi-square framework for the analysis of Free-Comment and Check-All-That-Apply data

2021

International audience; Free-Comment (FC) and Check-All-That-Apply (CATA) provide a contingency table containing citation counts of descriptors by products. The analyses performed on this table are most often related to the chi-square statistic. However, such practices are not well suited because they consider experimental units as being the citations (one descriptor for one product by one subject) while the evaluations (vector of citations for one product by one subject) should be considered instead. This results in incorrect expected frequencies under the null hypothesis of independence between products and descriptors and thus in an incorrect chi-square statistic. Thus, analyses related …

Planification expérimentale en agroalimentaire

2006

Propagation des distributions - Détermination des incertitudes par la méthode de Monte Carlo

2013

Le supplément 1 [JCGM 101:2008] du guide pour l'expression des incertitudes de mesure de 2008 complète le GUM (Guide to the expression of uncertainty in measurement) [JCGM 100:2008] en proposant une nouvelle approche pour l'estimation des incertitudes de mesure. Il concerne la propagation des distributions des variables (paramètres) d'entrée à travers un modèle mathématique du processus de mesure. C'est une alternative pratique du GUM lorsque celui-ci n'est pas facilement applicable, par exemple, si la propagation sur la base du développement de Taylor au premier ordre n'est pas satisfaisante (linéarisation du modèle inadéquate) ou si la fonction de densité de probabilité pour la grandeur d…

Towards automated and operational forest inventories with T-Lidar

2011

International audience; Forest inventory automation has become a major issue in forestry. The complexity of the segmentation of 3D point cloud is due to mutual occlusion between trees, other vegetation, or branches. That is why, the applications done until now are limited to the estimation of the DBH (Diameter at Breast Height), the tree height and density estimation. Furthermore other parameters could also be detected, such as volume or species of trees (Reulke and Haala) . . . This paper presents an effective approach for automatic detection, isolation of trees and DBH estimation. Tree isolation is achieved using an innovative approach based on a clustering methodology followed by a skele…

Extrapolation of the Species Accumulation Curve for Incomplete Species Samplings: A New Nonparametric Approach to Estimate the Degree of Sample Compl…

2015

9 pages; International audience; Incomplete species samplings are deemed to remain the common practice in those groups of animals, such as small or micro- invertebrates, with numerous species that often are more or less difficult to detect in the field. Thus, extrapolating the Species Accumulation Curve as far as possible beyond the actual sample size may thus serve as a useful (although imperfect) surrogate to the desired, but practically inaccessible, complete samplings. In this context, several kinds of theoretical or empirical models for the Species Accumulation Curve and also a lot of estimators of the asymptotic limit of the Curve (i.e. total species richness) have been proposed. The …

A Framework for Mesh Segmentation and Annotation using Ontologies

2015

International audience; Mesh segmentation and annotation using semantics has received an increased interest with the recent democratisation of 3D reconstruction methods. The common approach is to perform this task in two steps, by first segmenting the mesh and then annotating it. However, this approach does not allow one part to take advantage of the other. In image processing, some methods are combining segmentation and annotation, but they are not generic and require implementation adjustments or rewritings for each modification of the expert knowledge. In this work, we describe an original framework that mixes segmen-tation and annotation while minimizing the required geometric analysis …