Search results for "vitesse"
showing 10 items of 22 documents
Contribution to the development and the improvement of a digital model of the human body biofidelic HUByx by numerical methods for impact applications
2017
The study of human tolerance thresholds to impacts requires experiments on living or post mortem human subjects, which naturally raises ethical questions. To overcome these limitations, the development of numerical tools has led over the last few years to the implementation of numerical models more or less capable to accurately reproduce the mechanical behavior of the human body when subjected to various types of stresses. It is in this context that the numerical model HUByx (Hermaphrodite Biomechanics yx-model) has been developed within the research department COMM of the ICB lab at UTBM. This PhD work aims at validating and improving the biofidelity of the thoracic part of the HUByx model…
Les petites agglomérations françaises et espagnoles face à la grande vitesse ferroviaire : comment convertir l'accessibilité en attractivité ?
2013
Characterized by a similar size and radial structure, high-speed rail French and Spanish networks are designed to meet long distance accessibility needs of major metropolitan systems. However, the two systems serve a number of towns with less than 100,000 inhabitants, which understand this opportunity as means to improve their attractiveness. The comparison of the two networks, which systems obey to different operating principles, allows specifying the role played by the high speed in the precise situation of these small towns. Moreover, this comparison allows analyzing interactions between accessibility gains and development strategies that have been implemented. Beyond their diversity, th…
Matériaux composites soumis à de grandes vitesses de sollicitation
2006
International audience; L'objet de ce travail est de modéliser la réponse à des sollicitations quasi-statiques et dynamiques de deux matériaux composites utilisés dans l'industrie automobile : un tissu verre/polypropylène et une matrice polypropylène renforcée de fibres courtes en verre. Pour ce faire, des essais mécaniques à différentes vitesses de sollicitation (de 10-4s-1 à 100s-1 ) ont été menés. La campagne expérimentale nous a permis d'identifier pour chacun des matériaux les phénomènes dissipatifs prépondérants et de quantifier leur part dans la déformation totale, en fonction de la vitesse. Nous proposons ensuite un modèle unifié de comportement permettant de répondre de manière coh…
Modélisation numérique d’impacts à hautes vitesses par la méthode sans maillage Smoothed Particles Hydrodynamics. Application aux micro-impacts dans …
2021
Investigations on the ballistic behaviours of soft tissue materials are significant research in a medical and pharmaceutical framework. They mainly focus on particles penetrating or traveling into the soft materials. For instance, in the needle-free drug delivery, the micro-scale particles as drug powders are injected into skin with high velocity, and several factors should be considered such as the particle diameters, trajectories, and momentum or velocities of projectile in this process. There have been investigated by some experiments, but there is still no study from the numerical insights.The numerical methods are suitable to study these kinds of processes. Although grid-based methods …
Physiological responses of running intermittent exercises
2012
The aims of the present work were to analyze the physiological responses during intermittent exercise and to determine; i) an field test to assess the maximal aerobic velocity (MAV) for intermittent exercise; ii) the type of intermittent exercise could elicit maximal oxygen uptake (VO2max); iii) the physiological and neuromuscular factors that could limit intermittent exercise duration.The first study demonstrated that the MAV (MAV45-15) reached at the end of an incremental intermittent (45s run/ 15s rest) field test (45-15FIT) was relevant to elicit a high percentage of VO2max during a 30s-30s intermittent training session. The second and third studies demonstrated that intermittent exerci…
Quantitative study of cardiac wall motion from cine-MRI using frequency-based optical flow methods
2010
The aim of this thesis is to study parietal desynchronisation of the left ventricle from conventional cine-MRI. The first part of our work consisted in the quantification of the left ventricle wall motion of the heart directly from conventional retrospective SSFP type cine-MRI sequences used in the study of cardiac function. The developed methods for measuring displacements within the images are frequency-based optical flow methods. These techniques seem to be particularly adapted to MRI specificities. We have demonstrated their robustness in the event of Rician noise and pixel intensity variations as a function of time. These variations are often associated with the through-plane motion of…
Contribution to the investigation of dynamic responses of human tissues under high velocity impacts using finite element modeling
2022
Thoracic injuries happen frequently in various frameworks of high velocity impact biomechanics. Rib fractures and lung injuries are the most common hard and soft tissue injuries in human thorax. This thesis aims to contribute to the investigation of dynamic responses of human tissues especially ribs and soft tissues under high velocity impacts using finite element modeling. Firstly, a novel strain-rate-dependent elasto-hydrodynamic constitutive law of the synthetic polymer Styrene-Ethylene-Butylene-Styrene (SEBS) gel was proposed and implemented as a user material subroutine in Radioss (Altair Hyperworks) to interpret dynamic behaviors of SEBS gel under various loading configurations. Numer…
La fatigue mentale : marqueurs électrophysiologiques et stratégies de compensation
2021
Mental fatigue is a common phenomenon in modern society, causing an alteration in both cognitive and physical performances. It can lead to an increased risk of accidents, a drop in productivity, and certain disorders such as depression. The objective of this thesis work was to study this phenomenon of mental fatigue by investigating more specifically its electrophysiological markers, and to find compensatory strategies to limit and/or avoid its deleterious effects.The first study identified brain activity modulations during a prolonged modified Stroop task. An increase in theta and alpha waves, as well as a decrease in N100 and P300 amplitude reflecting a decrease in attention were observed…
Maintaining information in Short-Term Memory between 2 and 6 years old of age : temporal forgetting and helping in maintaining the goal
2014
Working memory is an essential component of thought that is highly involved in learning and academic achievement. However, it is rarely studied in preschoolers, mainly because of a lack of suitable paradigms. Therefore, this thesis investigated the functioning of working memory in children between 2 and 6 years. For this purpose, two original paradigms were used. They were designed to be close to game situations which should help young children to focus their attention on the task. Firstly it was shown that the recall performance decreased over time, even in the absence of an interfering task. Children of this age therefore use a passive maintenance, i.e. without spontaneously implementing …
L’appropriation locale de la grande vitesse ferroviaire en Europe
2012
Cet article s’intéresse à « l’appropriation locale » de la grande vitesse ferroviaire, c’est à dire à la capacité des acteurs locaux et régionaux à infléchir l’inscription spatiale des LGV conçues à une échelle plus large (nationale et européenne). La méthodologie s’appuie sur trois dimensions issues de l’analyse des réseaux –la morphologie, la topologie et le service–, complétées par l’observation des projets urbains. La configuration spatiale du réseau ainsi décrite, est comprise comme le résultat de l'expression d'un ensemble de pouvoirs qui témoigne de différents modes d’appropriation territoriale de la grande vitesse. Les réflexions portent sur quatre agglomérations en position intermé…