Search results for "pattern recognition"
showing 10 items of 2301 documents
Block Based Deconvolution Algorithm Using Spline Wavelet Packets
2010
This paper presents robust algorithms to deconvolve discrete noised signals and images. The idea behind the algorithms is to solve the convolution equation separately in different frequency bands. This is achieved by using spline wavelet packets. The solutions are derived as linear combinations of the wavelet packets that minimize some parameterized quadratic functionals. Parameters choice, which is performed automatically, determines the trade-off between the solution regularity and the initial data approximation. This technique, which id called Spline Harmonic Analysis, provides a unified computational scheme for the design of orthonormal spline wavelet packets, fast implementation of the…
Effect of Acoustic Wave Reflections on Space Charge Measurements with PEA Method
2018
The Pulsed Electro-Acoustic (PEA) method is the most used technique for space charge detection in solid dielectrics. The methodology is largely employed in the field of High Voltage Direct Current (HVDC) transmission and is based on the detection of acoustic waves generated by charges vibration. One of the most common problems arising during the detection is the presence of multiple reflections taking place due to the presence of means discontinuity in the different PEA cell components. This reflection phenomenon, if not well taken into account, could cause incorrect interpretation of the PEA output signal. It is easy to understand that a simulation model is a basic tool to understand the w…
Qualitative Comparison of Community Detection Algorithms
2011
Community detection is a very active field in complex networks analysis, consisting in identifying groups of nodes more densely interconnected relatively to the rest of the network. The existing algorithms are usually tested and compared on real-world and artificial networks, their performance being assessed through some partition similarity measure. However, artificial networks realism can be questioned, and the appropriateness of those measures is not obvious. In this study, we take advantage of recent advances concerning the characterization of community structures to tackle these questions. We first generate networks thanks to the most realistic model available to date. Their analysis r…
Testing the effects of pre-processing on voxel based morphometry analysis
2015
Voxel based morphometry (VBM) is an automated analysis technique which allows voxel-wise comparison of mainly grey-matter volumes between two magnetic resonance images (MRI). Two main analysis processes in VBM are possible. One is cross-sectional data analysis, where one group is compared with another to depict see the regions in the brain, which show changes in their grey-matter volume. Second is longitudinal data analysis, where MRIs, taken at different time points, are compared to see the regions in the brain that show changes in their grey matter volume for one time point with respect to another time point. Both types of analyses require pre-processing steps before performing the statis…
Fusion in the character table
1998
Suppose that P P is a Sylow p p -subgroup of a finite p p -solvable group G G . If g ∈ P g \in P , then the number of G G -conjugates of g g in P P can be read off from the character table of G G .
Choosing Optimal Seed Nodes in Competitive Contagion.
2019
International audience; In recent years there has been a growing interest in simulating competitive markets to find out the efficient ways to advertise a product or spread an ideology. Along this line, we consider a binary competitive contagion process where two infections, A and B, interact with each other and diffuse simultaneously in a network. We investigate which is the best centrality measure to find out the seed nodes a company should adopt in the presence of rivals so that it can maximize its influence. These nodes can be used as the initial spreaders or advertisers by firms when two firms compete with each other. Each node is assigned a price tag to become an initial advertiser whi…
Image classification based on 2D feature motifs
2013
The classification of raw data often involves the problem of selecting the appropriate set of features to represent the input data. In general, various features can be extracted from the input dataset, but only some of them are actually relevant for the classification process. Since relevant features are often unknown in real-world problems, many candidate features are usually introduced. This degrades both the speed and the predictive accuracy of the classifier due to the presence of redundancy in the candidate feature set. In this paper, we study the capability of a special class of motifs previously introduced in the literature, i.e. 2D irredundant motifs, when they are exploited as feat…
Thermal modelling of the ATHENA X-IFU filters
2018
Copyright 2018 Society of Photo-Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. The X-IFU instrument of the ATHENA mission requires a set of thermal filters to reduce the photon shot noise onto its cryogenic detector and to protect it from molecular contamination. A set of five filters, operating at different nominal temperatures corresponding to the cryostat shield temperatures, is currently baselined. The knowledge of the actual filter temperature profi…
Rapid prototyping for micro-engineering and microfluidic applications: Recycled pmma, a sustainable substrate material
2018
Poly(methylmethacrylate), PMMA, is one of the most commonly used thermoplastics for the manufacture of micromechanical and microfluidic devices, due to its optical transparency, rigid mechanical properties, low cost and good workability in conjunction with its rapid prototyping and mass manufacturing. Recent advances in the rapid-prototyping fields have allowed the production of precise features compatible with microfluidic structures and accelerated the conversion process from bench-side to mass market. For example, to address the need for fast design cycles using material compatible with mass manufacturing, we have developed an ultrafast prototyping technique for the manufacture of multil…
Étude d'un système de stéréo-vision hybride
2013
National audience; On considère dans ce travail un système de vision hybride fixe composé d'une caméra fisheye et d'une caméra PTZ dans un environnement rigide. Nous souhaitons être en mesure d'orienter la caméra mécanisée sur une cible visible depuis l'image omnidirectionnelle de manière à obtenir une image de bonne définition de l'objet d'intérêt à partir de la caméra PTZ. Nous proposons dans cet article d'utiliser la modélisation sphérique des images ainsi que les propriétés de la géométrie épipolaire afin d'initialiser la localisation de la cible dans la caméra PTZ.