L'étude des phénomènes de marée gravimétrique

Cet article présente une description des phénomènes de marée terrestre et des méthodes de mesure. Les résultats des profils mondiaux de marée gravimétrique sont corrigés des effets indirects liés aux marées océaniques. Une corrélation entre marées gravimétriques, flux de chaleur et tectonique globale est proposé

Renforcer l’analyse réflexive des tuteurs en formation

Comprend des références bibliographiquesNous présentons dans cette communication l’étude de l’engagement des élèves d’une école d’ingénieur française dans un cours en fonction de sa modalité : cours en présentiel ou cours-vidéo. Sur la base de l’analyse de diverses données prises auprès de ces élèves sur deux ans - deux questionnaires écrits et 12 interviews - nous pouvons conclure que l’engagement est soutenu, indépendant de la modalité. Nous attribuons ce résultat entre autres aux caractéristiques des apprenants qui sont fortement motivés et possèdent une bonne connaissance de soi ce qui leur permet de choisir et de créer des conditions de travail adaptées afin de réussir leurs études

Essais d'adaptation de production massive de juvéniles de Clarias gariepinus en conditions rurales

Adaptive Trials for Intensive Clarias gariepinus fingerling to Rural Conditions. Artificial reproduction and fingerling production of the African catfish Clarias gariepinus (Burchell 1822) have been tested under less controlled conditions to adapt the intensive technology used by Aquafarm (Tihange, Belgium) to rural conditions present in developing countries. The main aim was to compare the efficiency of ovaprim a synthesised hormone with catfish pituitary extracts. Fecundity and quality of eggs (egg weight) were not significantly different. Incubation results on water hyacinth and on mosquito mesh frames were compared to those obtained in Zoug jars; the latter showed a higher hatching rate (67%) than water hyacinth (39%) and mosquito mesh frames (44%). Larvae were stocked at different stocking rates in ponds (T1: 800 larvae.m-3 and T2: 1600 larvae. m-3 ) and in tanks (T3: 3200 larvae.m-3 et T4: 6400 larvae.m-3). After a 50-day nursing period, no significant difference (P> 0.05) was observed for specific growth rate (SGR) and survival rate, but better SGR were observed in ponds (18.34%.d-1) than in tanks (16.81%.d-1). In general, production was slightly higher in tanks than in ponds being related to a higher stocking density. Significantly higher harvests were obtained from tanks with higher stocking densities but the sizes of the larvae were very heterogeneous. In such case, it is recommended to grade the larvae at 6 or 7 days intervals using different mesh sizes (from 3 to 5 mm). These less intensive rearing conditions gave nevertheless good fingerling productions

Cornual heterotopic pregnancy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Cornual heterotopic pregnancy is a very rare condition; its incidence remains unknown. We report a case of cornual heterotopic pregnancy managed by laparoscopy and guided methotrexate injection into the cornual sac.</p> <p>Case presentation</p> <p>A cornual heterotopic pregnancy was diagnosed at 9 weeks of amenorrhoea in a 31-year-old healthy woman. Ultrasound examination showed a well-formed intrauterine gestation without detectable fetal heart pulsation, together with a gestational sac situated in the right cornual region. After uterine evacuation under ultrasound guidance, the diagnosis of cornual pregnancy was confirmed on laparoscopy followed by methotrexate injection into the cornual gestational sac.</p> <p>Conclusions</p> <p>Cornual heterotopic pregnancy is a very rare and potentially dangerous condition. Diagnosis of cornual pregnancy could be made on ultrasound examination in this patient. Laparoscopy was useful as an alternative in confirming the diagnosis and aided further treatment.</p

Tidal gravity observations at Mt. Etna and Stromboli: results concerning the modeled and observed tidal factors

Continuous gravity observations performed in the last few years, both at Mt. Etna and Stromboli, have prompted the need to improve the tidal analysis in order to acquire the best corrected data for the detection of volcano related signals. On Mt. Etna, the sites are very close to each other and the expected tidal factor differences are negligible. It is thus useful to unify the tidal analysis results of the different data sets in a unique tidal model. This tidal model, which can be independently confirmed by a modeling of the tidal parameters based on the elastic response of the Earth to tidal forces and the computation of the ocean tides effects on gravity, is very useful for the precise tidal gravity prediction required by absolute or relative discrete gravity measurements. The change in time of the gravimeters’ sensitivity is also an important issue to be checked since it affects not only the results of tidal analysis but also the accuracy of the observed gravity changes. Conversely, if a good tidal model is available, the sensitivity variations can be accurately reconstructed so as to retune observed tidal records with the synthetic tide, since the tidal parameters are assumed to be constant at a given location

APPRENDRE LES COMPETENCES TRANSVERSALES: Un atelier pour révéler ses talents

International audienceLe travail en groupe et la communication sont des compétences indispensables au métier d'ingénieur. En 1 ère année, les étudiants de l'Ecole Polytechnique de Louvain (EPL) doivent adopter des méthodes de travail collectif en vue de développer des compétences ad hoc. Cet article présente une expérience menée en début de curriculum

High precision tilt observation at Mt. Etna Volcano, Italy

In 2007-2008, we installed on Mt. Etna two deep tilt stations using high resolution, self-leveling instruments. These installations are the result of accurate instrument tests, site selection, drilling and sensor positioning that has allowed detecting variations related to the principal diurnal and semidiurnal tides for first time on Mt. Etna using tilt data. We analyzed the tidal effects recorded on tilt signals and we removed tidal effects from signals, thereby allowing to detect changes of about 20 nanoradians with a considerable improvement respect to the previous installation. Tilt changes have accompanied the Mt. Etna main eruptive phases and are generally related to the rapid rise of magma and formation of dikes and eruptive fissures. However, tilt changes characterize lava fountains, earthquakes and inflation-deflation phases. The 2008-2009 eruption represents an example of the potential of these tiltmeters providing new perspectives for highly precise monitoring of ground deformation on volcanoes

Se former en ligne au Tutorat : un défi pour les assistants-chercheurs

L’École Polytechnique de Louvain (EPL) propose depuis de nombreuses années une formation en présentiel pour les étudiants de master. Ils sont appelés les tuteurs et ils encadrent des étudiants de première année dans des enseignements de types : travaux pratiques, apprentissages par problèmes (APP), des projets, apprentissages par exercices (APE), des laboratoires. Une formation en ligne a été créée pour un public d’assistants-chercheurs aux rôles du tuteur. Cette formation hybride intitulée « Tutorer l’Apprentissage en Groupe (TAG) » vise à permettre aux assistants-chercheurs novices et expérimentés de se questionner sur leurs manières d’enseigner pour les améliorer. Nous analysons particulièrement ici les interventions des tuteurs qui encadrent la formation en ligne et leurs impacts pour l’apprentissage. Suite à l’analyse des interventions faites en ligne et en présentiel, et plus précisément en regardant les effets de ces interventions sur le plan métacognitif (réflexivité), nous constatons un besoin patent de la présence du tuteur humain de manière plus régulière au sein de la formation que nous proposons. Ce besoin se manifeste par un sentiment d’isolement de la part des assistants les premières semaines, du besoin de se sentir appartenir à un groupe, de connaître les réflexions des autres pour être motivés à apprendre, et ce, même si tous les assistants évoquent que la formation, de par son dispositif, permet très clairement de se questionner sur ses pratiques de tuteur de manière continue pour les améliorer

Involving recreational snorkelers in inventory improvement or creation: a case study in the Indian Ocean.

Four amateur naturalists and underwater photographers established sixty first records and discovered three species probably new to science at Reunion Island (Indian Ocean) between January 2010 and January 2016, although the marine environment of this island has been studied for some forty years by professional scientists. These results were achieved after snorkeling in coastal areas at a maximum depth of 2 m. All records were validated by professional experts of the relevant groups, with appropriate reservations for photograph-based identifications. The analysis of the methodology used by this group of reef observers highlights three central elements: individual initiative, regular random-path snorkeling practice by local observers, and availability of correspondent observers with sufficient naturalist skills to select accurate data and manage an optimal link with professional scientists. Such achievement emphasizes the efficiency of a citizen- based approach aimed at creating or improving local fauna inventories and discovering new species. Considering that ecological data can be collected during observers' random-path snorkeling sessions, such a project is also of interest for local conservationists and marine ecosystems managers. We therefore recommend the inclusion of these practices in the process of designing standardised observation programs aimed at non-professionals everywhere snorkeling can be practiced, especially in under-studied regions.N

Development of a power hardware in the loop simulation of an islanded microgrid

In this paper a Power Hardware in the loop simulation has been realized to test in a safely way the performances and reliability of a device called “PowerCorner” used to supply an islanded microgrid. A real-time model has been developed in order to simulate the microgrid, batteries and photovoltaic panels. Some modeling criterions have been proposed to reduce time-step simulation and enhancing the Power Hardware in the loop simulation stability. Power Hardware in the loop simulation is used to emulate the AC and DC environments around the power inverters. On the DC side, DC power amplifier is used to emulate photovoltaic power plants and storage devices made on Lithium batteries. On the AC side, AC power amplifier is used to emulate the behavior of the microgrid. These two power amplifiers are controlled by a digital real time simulator which embeds the dynamic behavior of both DC and AC sides