Search results for "Measure"
showing 10 items of 4687 documents
3D part inspection path planning of a laser scanner with control on the uncertainty
2011
International audience; This article concerns the measurement process of mechanical parts using laser scanners. From the point of view of industrial applications, the objective is to guarantee the measurement accuracy during the scanning with regard to the geometrical product specifications. The proposed method can be summarized as follow: the first step consists of analyzing the interval of tolerance for the different specifications and to attribute to every geometrical entity a maximal uncertainty of measurement. This uncertainty depends on the angle of incidence between the laser plane and the scanned surface. In the second step, an approach based on the concept of visibility is used fro…
3D Displacements and Strains Solid Measurement based on the Surface Texture with a Scanner Laser
2013
International audience; The developments of non-contact measurement are today widely due to the unprecedented progress of optronic. The applications of these techniques are wide and varied for the 3D measurement of industrial products. In addition to the forms and dimensions, we show in this paper that the devices of laser scanning permit to measure displacements and deformations. In this case, it is necessary to follow a solid particle in its motion. It is then necessary to identify the particle between two configurations of the body before and after displacement. The method of greyscale patterns, obtained by applying a spray, is generally used. The originality of the proposed method is ba…
Taking digitized points quality into account in geometrical specification measurement by laser sensor
2004
International audience; Today, the new measurement techniques without contact like the laser sensors are used more and more in industrial applications. They allow to obtain many points in a short time. However these techniques have a less good accuracy than the classical process with contact probe for metrology application. The work presented in this paper, is part of a research project on the in-process product inspection. In the case of in-process product inspection, the throughput time must be the shortest with a good dimensional accuracy. So, it is necessary to increase the measurement accuracy of the points cloud for using the laser scanners. For this first approach, we suggest to buil…
Comparison of Flow Measurement by 4D Flow Magnetic Resonance Imaging and by Particles Image Velocimetry on Phantom of Abdominal Aortic Aneurysm
2016
International audience; Predicting the rupture of Aortic Aneurysms is a complex problem that interests, from several decades, many researchers. The works on this issue are very complex, involving both the study of mechanical behavior of the artery as the flow of blood. The Magnetic Resonance Imaging (MRI) technique allows to obtain anatomic information of the arteries, than the flow inside thereof. The goal of this study is an inter comparison betweenflow data from MRI and those obtained by Particle Image Velocimetry (PIV). An experimental device simulating hemodynamic circulation is used. Initially in order to validate the device, the flow in a cylindrical glass tube is measured by these t…
Strain fields measurement of non-rigid solid by scanning laser coupled with camera
2013
International audience; Abstract. Today, the techniques of measurement without contact by scanning laser are increasingly used. These techniques allow to measure 3D objects without contact and the measurement rates can reach few thousand points by second that is very adapted to complex shapes. To measure displacements and deformations, it is necessary to follow a solid particle in its motion between two configurations of the body before and after displacement. The method of stereovision based on grayscale patterns, obtained by applying a spray, is generally used. The results are obtained by two correlations: spatial and temporal correlations. An alternative method consists to use a scanner …
Digital Correlation Method Based on Microgeometrical Texture Patterns for Strain Fields Measurements
2005
International audience; Digital correlation method is widely used in experimental mechanics to obtain the deformation field. Currently this method is applied with digital images of the initial and deformed surface sprayed with black or white painting. Speckle patterns are then captured and the correlation can be made with high 0.01 pixel accuracy in 2D-cases. In three-dimensions, the stereo-correlation can be used with a lower accuracy. The work presented in this paper, is a first approach based on the use of a 3D laser scanner in the objective of three-dimensional strain field measurement. The digital speckle patterns are not given by gray level but from the micro-geometrical surface textu…
Inconsistency measuring over multisets of formulas
2018
International audience; Measuring Inconsistency in Information : The concept of measuring inconsistency in information was developed by John Grant in a 1978 paper in the context of first-order logic. For more than 20 years very little was done in this area until in the early 2000s a number of AI researchers started to formulate new inconsistency measures primarily in the context of propositional logic knowledge bases. The aim of this volume is to survey what has been done so far, to expand inconsistency measurement to other formalisms, to connect it with related topics, and to provide ideas for further research in a topic that is particularly relevant now in view of the many inconsistencies…
Localization from inertial data and sporadic position measurements
2020
International audience; A novel estimation strategy for inertial navigation in indoor/outdoor environments is proposed with a specific attention to the sporadic nature of the non-periodic measurements. After introducing the inertial navigation model, we introduce an observer providing an asymptotic estimate of the plant state. We use a hybrid dynamical systems representation for our results, in order to provide an effective, and elegant theoretical framework. The estimation error dynamics with the proposed observer shows a peculiar cascaded interconnection of three subsystems (allowing for intuitive gain tuning), with perturbations occurring either on the jump or on the flow dynamics (depen…
Semantic Measures: A State of the Art
2014
Significant advances in terms of syntactic, structural and schematic heterogeneity have been achieved by adopting conventions and standards. The IT community is now trying to solve the problem of semantic heterogeneity (particularly in the Semantic Web field). To reach this objective, it is necessary to enable machines to understand the semantics of terms. Semantics, as opposed to syntax, defines the mental representation of concepts corresponding to the symbols used in texts or images. When a person reads a text, he uses a semantization process which enables him to associate an interpretation to each sign identified. This operation uses a number of underlying processes such as measuring se…
Statistical consequences of the Devroye inequality for processes. Applications to a class of non-uniformly hyperbolic dynamical systems
2005
In this paper, we apply Devroye inequality to study various statistical estimators and fluctuations of observables for processes. Most of these observables are suggested by dynamical systems. These applications concern the co-variance function, the integrated periodogram, the correlation dimension, the kernel density estimator, the speed of convergence of empirical measure, the shadowing property and the almost-sure central limit theorem. We proved in \cite{CCS} that Devroye inequality holds for a class of non-uniformly hyperbolic dynamical systems introduced in \cite{young}. In the second appendix we prove that, if the decay of correlations holds with a common rate for all pairs of functio…