Evaluer l'acceptabilité des politiques publiques: la méthode des focus groups

Communication issue du colloque "Evaluation des politiques de sécurité routière: méthodes, outils et limites" organisé le 9 juin 2015 à Paris par le Centre d'études et d'expertise sur les risques, l'environnement, la mobilité et l'aménagement et l’Institut français des sciences et technologies des transports, de l'aménagement et des réseaux (Ifsttar), avec le soutien de la Délégation à la Circulation et la Sécurité Routières.National audienc

Les focus groups : Intérêts et principes appliqués à l’acceptabilité des politiques publiques de sécurité routière

Un focus group (FG), appelé également entretien de groupe, est un groupe d\u27individus selectionnés et réunis par des chercheurs pour discuter et réagir, à partir de leur expérience personnelle, de leur perception d\u27un thème donné et cela dans un environnement permissif et non menaçant... L’objectif de ce chapitre est de présenter la méthode des FG, les étapes essentielles, les difficultés auxquelles il faut faire face et les solutions à y apporter pour étudier l’acceptabilité des politiques publiques de sécurité routière.

Monitoring the Petermann Ice Island with TanDEM-X

This paper presents the processing of TanDEM-X acquisitions for the monitoring of the topography of the Petermann ice island. In this particular case the area under study is continuously moving and the acquisition geometry is changing, so the processing of the iceberg’s DEMs is challenging and additional effects are to be considered. The SAR processing chain used is presented and the results obtained summarized, showing the effects and limitations observed during the process

LES of two-phase reacting flows: stationary and transient operating conditions

L'allumage et le réallumage de haute altitude présentent de grandes difficultés dans le cadre des chambres de combustion aéronautiques. Le succès d'un allumage dépend de multiples facteurs, des caractéristiques de l'allumeur à la taille des gouttes du spray en passant par le niveau de turbulence au point d'allumage. Déterminer la position optimale de l'allumeur ou le potentiel d'allumage d'une source d'énergie donnée à une position donnée sont ainsi des paramètres essentiels lors du design de chambre de combustion. Le but de ces travaux de thèse est d'étudier l'allumage forcé des chambres de combustion aéronautiques. Pour cela, des Simulation numériques aux Grandes Echelles (SGE) d'écoulements diphasiques réactifs sont utilisées et analysées. Afin de les valider, des données expérimentales issues du banc MERCATO installé à l'ONERA Fauga-Mauzac sont utilisées. Cela permet dans un premier temps de valider la méthodologie ainsi que les modèles utilisés pour les SGE diphasiques évaporantes avant leur utilisation dans d'autres conditions d'écoulement. Le cas diphasique réactif statistiquement stationnaire est ensuite comparé aux données disponibles pour évaluer les modèles en condition réactives. Ce cas est étudié plus en détail à travers l'analyse de caractéristiques de la flamme. Celle-ci semble être le théâtre de régimes de combustion très différents. On note aussi que la détermination de la méthode numérique la plus appropriée pour le calcul d'écoulements diphasiques n'est pas évidente. De plus, deux méthodes numériques différentes peuvent donner des résultats en bon accord avec l'expérience et pourtant avoir des modes de combustion différents. Les capacités de la SGE à correctement calculer un écoulement diphasique réactif étant validé, des SGE du phénomène transitoire d'allumage sont effectuées. La sensibilité observée expérimentalement de l'allumage aux conditions initiales, i.e. à l'instant de claquage, est retrouvé par les SGE. L'analyse met en évidence le rôle prépondérant de la dispersion du spray dans le développement initial du noyau de flamme. L'utilisation des SGE pour calculer les séquences d'allumage fournie de nombreuses informations sur le phénomène d'allumage, cependant d'un point de vue industriel, cela ne donne pas de résultat optimal, à moins de ne tester toutes les positions, ce qui rendrait le coût CPU déraisonnable. Des alternatives sont donc nécessaires et font l'objet de la dernière partie de ces travaux. On propose de dériver un critère local d'allumage, donnant la probabilité d'allumage à partir d'un écoulement diphasique (air et carburant) non réactif instationnaire. Ce modèle est basé sur des critères liés aux différentes phases menant à un allumage réussi, de la formation d'un premier noyau à la propagation de la flamme vers l'injecteur. Enfin, des comparaisons avec des données expérimentales sur des chambres aéronautiques sont présentées et sont en bon accord, indiquant que le critère d'allumage proposé, couplé avec une SGE d'écoulement diphasique non réactif, peut être utilisé pour optimiser la puissance et la position du système d'allumage. ABSTRACT : Ignition and altitude reignition are critical issues for aeronautical combustion chambers. The success of ignition depends on multiple factors, from the characteristics of the igniter to the spray droplet size or the level of turbulence at the ignition site. Finding the optimal location of the igniter or the potential of ignition success of a given energy source at a given location are therefore parameters of primary importance in the design of combustion chambers. The purpose of this thesis is to study forced ignition of aeronautical combustion chambers. To do so, Large Eddy Simulations (LES) of two-phase reacting flows are performed and analyzed. First, the equations of the Eulerian formalism used to describe the dispersed phase are presented. To validate the successive LES, experimental data from the MERCATO bench installed at ONERA Fauga-Mauzac are used. It allows to validate the two-phase evaporating flow LES methodology and models prior to its use to other flow conditions. The statistically stationary two-phase flow reacting case is then compared to available data to evaluate the model in reacting conditions. This case is more deeply studied through the analysis of the characteristics of the flame. This last one appears to experience very different combustion regimes. It is also seen that the determination of the most appropriate methodology to compute two-phase flow flame is not obvious. Furthermore, two different methodologies may both agree with the data and still have different burning modes. The ability of the LES to correctly compute burning two-phase flow being validated, LES of the transient ignition phenomena are performed. The experimentally observed sensitivity of ignition to initial conditions, i.e. to sparking time, is recovered with LES. The analysis highlights the major role played by the spray dispersion in the development of the initial flame kernel. The use of LES to compute ignition sequences provides a lot of information about the ignition phenomena, however from an industrial point of view, it does not give an optimal result, unless all locations are tested, which brings the CPU cost to unreasonable values. Alternatives are hence needed and are the objective of the last part of this work. It is proposed to derive a local ignition criterion, giving the probability of ignition from the knowledge of the unsteady non-reacting two-phase (air and fuel) flow. This model is based on criteria for the phases of a successful ignition process, from the first kernel formation to the flame propagation towards the injector. Then, comparisons with experimental data on aeronautical chambers are done and show good agreement, indicating that the proposed ignition criterion, coupled to a Large Eddy Simulation of the stationary evaporating two-phase non-reacting flow, can be used to optimize the igniter location and power

Regularized characteristic boundary condition for the Lattice Boltzmann methods at high Reynolds number flows

This paper reports the investigations done to adapt the Characteristic Boundary Conditions (CBC) to the Lattice-Boltzmann formalism for high Reynolds number applications. Three CBC formalisms are implemented and tested in an open source LBM code: the baseline one-dimension inviscid (BL-LODI) approach, its extension including the effects of the transverse terms (CBC-2D) and a local streamline approach in which the problem is reformulated in the incident wave framework (LS-LODI). Then all implementations of the CBC methods are tested for a variety of test cases, ranging from canonical problems (such as 2D plane and spherical waves and 2D vortices) to a 2D NACA profile at high Reynolds number (Re = 100,000), representative of aeronautic applications. The LS-LODI approach provides the best results for pure acoustics waves (plane and spherical waves). However, it is not well suited to the outflow of a convected vortex for which the CBC-2D associated with a relaxation on density and transverse waves provides the best results. As regards numerical stability, a regularized adaptation is necessary to increase the Reynolds number. The so-called regularized FD adaptation, a modified regularized approach where the off-equilibrium part of the stress tensor is computed thanks to a finite difference scheme, is the only tested adaptation that can handle the high Reynolds computation

Traditional horticultural knowledge change in a rural population of the Patagonian steppe

We investigated traditional horticultural knowledge related to plant species cultivated in homegardens in an arid rural population of North-western Patagonia, Argentina. By means of semi-structured interviews and field visits to the cultivated areas we analyzed floristic composition and structure of: vegetable-gardens, greenhouses and gardens. We evaluated species richness, cover and biogeographicalorigin in each cultivated area and analyzed the influence of socio-cultural factors, such as age and gender, on informants? cultivation practice. A total of 124 species was found: 75 species in vegetable-gardens, 63 in greenhouses and 68 in gardens. In all cultivated areas, most plant species (91%) were exotic and mainly used for edible purposes. Plant richness in homegardens increased with informants? age and both men and women play a relevant role in the maintenance of cultivated areas. Traditional knowledge in this community has been suffering an erosion process, which is in part influenced by the intervention of extension agents. However, their presence creates the possibility of integrating new and ancestral practices, favoring development of knowledge of a hybrid, syncretic nature. Alongside these changes, Pilcaniyeu inhabitants still maintain traditional homegardens cultivation, through which we can appreciate the intricate relationship between people and their physical, historical, cultural and spiritual contexts.Fil: Eyssartier, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Ladio, Ana Haydee. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Lozada, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Skills improvement after observation or direct practice of a simulated laparoscopic intervention

BACKGROUND: Laparoscopic skills are more and more often being learned on simulators. PURPOSE: To assess the respective roles of observation and direct practice in the retention of laparoscopic procedural skills. BASIC PROCEDURES: Twelve surgical residents were included in a two-session laparoscopic training course. During the first session (S1), one participant completed a cholecystectomy on the Simbionix LAPMentor™ and then observed his colleague carrying out a total hysterectomy and vice versa. During the second session (S2), each participant completed both interventions. Skills evaluation was assessed using the Objective Structured Assessment of Technical Skills (OSATS) global rating scale and LAPMentor™ metrics. MAIN FINDINGS: Mean OSATS score during the first session was 19.3±5.1, and increased by 37% in the group of former observer students (S2O, P=0.003), and by 54% in the group of former practising students (S2A, P=0.001). Self- and peer-grading results were concordant with the supervisor\u27s evaluation. Detailed analysis of LAPMentor™ metrics showed a trend toward more parameters being improved in group S2A as compared to group S2O on both interventions. The most significant improvements concerned the time of completion for the hysterectomy and the efficiency of cautery for the cholecystectomy. CONCLUSIONS: Observation of laparoscopic skills still allows for surgical improvement, but direct practice on a virtual reality trainer provides better results. Self- and peer-grading were concordant with the supervisor\u27s evaluation. This work may advocate the integration of both personal training on simulators and surgical observation into residents\u27 surgical curricula

Proyecto de adecuación de las instalaciones de una oficina de pública concurrencia

Se van a diseñar las instalaciones técnicas necesarias para la adecuación de una oficina de pública concurrencia de 2250m2 acorde a la legislación actual. En este caso van a ser proyectadas las siguientes instalaciones climatización, iluminación, instalación eléctrica, agua caliente sanitaria, protección contra incendios, instalación fotovoltaica en cubierta, eficiencia energética. Todas estas instalaciones serán dimensionadas mediante el uso de diferentes softwares comerciales, acompañando el trabajo de comprobaciones pertinentes en cada una de las instalaciones

COMPARISON OF PEAK LUMBAR LORDOSIS BETWEEN SOME BASIC MOVEMENTS OF RHYTHMIC GYMNASTICS

To assist coaches in managing gymnasts, a good knowledge of the movements most likely to cause back pain is required. In rhythmic gymnastics (RG), this can be considered as identifying movements involving very high lumbar curvatures. To quantify the lumbar lordosis during some basic RG movements (ring, penché, penché with rotation, split leap, turning split leap, and front and back walkovers), eight gymnasts were enrolled and a 3D motion analysis was performed based on motion capture data, a musculoskeletal model and low-dose biplanar radiographs for model personalisation purposes. The ring and both the front and back walkovers were the movements studied involving the lumbar spine in extension the most but also resulting in the highest dispersion between gymnasts. Hence, future works should investigate the causes of this greater dispersion