Search results for "Distortion"
showing 10 items of 309 documents
Elliptic equations and maps of bounded length distortion
1988
On considere l'equation elliptique d'ordre 2: L(u)=Σ i,f=1 n ∂ 1 (a ij ∂ ju )=0 ou les coefficients a ij sont des fonctions C 1 dans un domaine D de R n
Structure and dielectric properties of Na0.5Bi0.5TiO3-CaTiO3 solid solutions
2016
Despite wide studies of Na0.5Bi0.5TiO3, structure of this material and its connection with the observed physical properties still raise numerous questions due to mutually contradicting results obtained. Here, structure and dielectric properties of poled and unpoled Na0.5Bi0.5TiO3-CaTiO3 solid solutions are studied, projecting the obtained concentration dependence of structure and dielectric properties on pure Na0.5Bi0.5TiO3 as the end member of this material group. X-ray diffraction patterns for Na0.5Bi0.5TiO3-CaTiO3 solid solutions reveal dominating of an orthorhombic Pnma phase, even for the compositions approaching the end composition (Na0.5Bi0.5TiO3), whereas structure of pure Na0.5Bi0.…
The Effect of the Harmonic Content Generated by AC/DC Modular Multilevel Converters on HVDC Cable Systems
2019
With the increasing penetration of renewable and decentralized energy sources into the power grid, an extended use of DC voltages is expected on both distribution and transmission levels. Generation of DC voltages by means of voltage source converters is associated with a wide spectrum of harmonic distortions at converter terminals, both on the ac and on the dc sides. This can lead to partial discharges in power cables, which deteriorate insulation material thus weakening its performance and reducing cable life-time. In the previously published paper, the effect of harmonic distortion on appearance of partial discharges in cable insulation was evaluated. Here, the study related to the PD be…
Cycloaddition of Strained Cyclic Alkenes and Ortho-Quinones : A Distortion/Interaction Analysis
2020
The chemistry of strained unsaturated cyclic compounds has experienced remarkable growth in recent years via the development of metal–free click reactions. Among these reactions, the cycloaddition of cyclopropenes and their analogues to ortho-quinones has been established as a highly promising click reaction. The present work investigates the mechanism involved in the cycloaddition of strained dienes to ortho-quinones and structural factors that would influence this reaction. For this purpose, we use B97D density functional theory calculations throughout, and for relevant cases, we use spin component–scaled MP2 calculations and single–point domain-based local pair natural orbital coupled cl…
A macroscale FEM-based approach for selective laser sintering of thermoplastics
2017
A numerical approach to model the selective laser sintering (SLS) of polypropylene is proposed. A 3D thermal model was developed and thus enables the prediction of the temperature fields and the extension of the sintered area in the powder bed taking into account the phase change during multiple laser passes. Powderâliquid, liquidâsolid and solidâliquid phase changes were modelled during the SLS and the subsequent cooling processes. Then, a 3D thermomechanically coupled model was set up based on the temperature results of the thermal model in order to predict the distortion of the produced parts after cooling down. Different pre-heating temperatures were considered, highlighting their…
Scale invariant line matching on the sphere
2013
International audience; This paper proposes a novel approach of line matching across images captured by different types of cameras, from perspective to omnidirectional ones. Based on the spherical mapping, this method utilizes spherical SIFT point features to boost line matching and searches line correspondences using an affine invariant measure of similarity. It permits to unify the commonest cameras and to process heterogeneous images with the least distortion of visual information.
Measuring trunk orientation with a CMOS camera: feasibility and accuracy.
2007
International audience; The purpose of this study was to develop and validate a new tool to objectively quantify trunk orientation at the bedside, especially dedicated to the measurement of the lateropulsion in acute and subacute stroke patients. We developed software to analyze 2D movement with a CMOS camera (Logitech Quickcam Pro 4000) and to calculate the orientation of a segment defined by two color markers. First, the accuracy, reproducibility and noise when measuring segment orientations were evaluated with the CMOS camera placed in different positions, and second trunk orientation was measured in static and in dynamic conditions both with a CMOS camera and with a gold standard 3D vid…
Model Predictive Control for Shunt Active Filters With Fixed Switching Frequency
2016
This paper presents a modification to the classical Model Predictive Control algorithm, named Modulated Model Predictive Control, and its application to active power filters. The proposed control is able to retain all the advantages of a Finite Control Set Model Predictive Control whilst improving the generated waveforms harmonic spectrum. In fact a modulation algorithm, based on the cost function ratio for different output vectors, is inherently included in the MPC. The cost function-based modulator is introduced and its effectiveness on reducing the current ripple is demonstrated. The presented solution provides an effective and straightforward single loop controller, maintaining an excel…
FPGA Implementation of an Adaptive Filter Robust to Impulsive Noise: Two Approaches
2011
Adaptive filters are used in a wide range of applications such as echo cancellation, noise cancellation, system identification, and prediction. Its hardware implementation becomes essential in many cases where real-time execution is needed. However, impulsive noise affects the proper operation of the filter and the adaptation process. This noise is one of the most damaging types of signal distortion, not always considered when implementing algorithms, particularly in specific hardware platforms. Field-programmable gate arrays (FPGAs) are used widely for real-time applications where timing requirements are strict. Nowadays, two main design processes can be followed for embedded system design…
Static and dynamic body image in bulimia nervosa: mental representation of body dimensions and biological motion patterns.
2006
The aim of the present study was to find out whether in bulimia nervosa the perceptual component of a disturbed body image is restricted to the overestimation of one's own body dimensions (static body image) or can be extended to a misperception of one's own motion patterns (dynamic body image).Participants with bulimia nervosa (n = 30) and normal controls (n = 55) estimated their body dimensions by means of a photo distortion technique and their walking patterns using a biological motion distortion device.Not only did participants with bulimia nervosa overestimate their own body dimensions, but also they perceived their own motion patterns corresponding to a higher BMI than did controls. S…