820 research outputs found

    Observations of OH in comet Levy with the Nancay radio telescope

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    Due to extremely favorable excitation conditions, comet Levy (1990c) exhibited in August-September 1990 the strongest OH 18-cm signal ever recorded in a comet at the Nancay radio telescope. This unique opportunity was used to measure the OH satellite lines at 1612 and 1721 MHz, to perform extensive mapping of the OH radio emission and to make a sensitive evaluation of the cometary magnetic field, of the H2O outflow velocity and of the OH production rate

    Engage D3.5 Opportunities for innovative ATM research (interim report)

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    This document reports on the topics and academic disciplines of past Exploratory Research projects, notably SESAR Workpackage E (long-term and innovative research) and SESAR Exploratory Research (ER) with a view of tracing the evolution of research as well as opportunities for future research. This analysis is complemented with relevant activities in Engage, such as the Engage thematic challenges

    Engage D3.10 Research and innovation insights

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    Engage is the SESAR 2020 Knowledge Transfer Network (KTN). It is managed by a consortium of academia and industry, with the support of the SESAR Joint Undertaking. This report highlights future research opportunities for ATM. The basic framework is structured around three research pillars. Each research pillar has a dedicated section in this report. SESAR’s Strategic Research and Innovation Agenda, Digital European Sky is a focal point of comparison. Much of the work is underpinned by the building and successful launch of the Engage wiki, which comprises an interactive research map, an ATM concepts roadmap and a research repository. Extensive lessons learned are presented. Detailed proposals for future research, plus research enablers and platforms are suggested for SESAR 3

    Asymmetry Function of Interstellar Scintillations of Pulsars

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    A new method for separating intensity variations of a source's radio emission having various physical natures is proposed. The method is based on a joint analysis of the structure function of the intensity variations and the asymmetry function, which is a generalization of the asymmetry coefficient and characterizes the asymmetry of the distribution function of the intensity fluctuations on various scales for the inhomogeneities in the diffractive scintillation pattern. Relationships for the asymmetry function in the cases of a logarithmic normal distribution of the intensity fluctuations and a normal distribution of the field fluctuations are derived. Theoretical relationships and observational data on interstellar scintillations of pulsars (refractive, diffractive, and weak scintillations) are compared. Pulsar scintillations match the behavior expected for a normal distribution of the field fluctuations (diffractive scintillation) or logarithmic normal distribution of the intensity fluctuations (refractive and weak scintillation). Analysis of the asymmetry function is a good test for distinguishing scintillations against the background of variations that have different origins

    Analyse du Cycle de Vie de la filière hydrogène énergie – Première étape : définition des objectifs et du champ de l'étude

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    National audienceDans le contexte actuel de pollution atmosphérique, de démocratisation de l'énergie et d'épuisement des ressources fossiles, le Groupement des Ecoles des Mines (GEM) s'est lancé dans la recherche d'une filière énergétique propre et renouvelable dans le secteur du transport: la production à partir de biomasse, le stockage et l'utilisation de l'hydrogène dans une pile à combustible « Polymer Exchange Membran Fuel Cell ». Le GEM, souhaitant connaître les performances environnementales de cette filière tout le long de son cycle de vie, a commandité la réalisation d'une Analyse du Cycle de Vie (ACV) de cette filière. Cette ACV compare d'un point de vue environnemental la filière hydrogène à la filière essence et à la filière bioéthanol (issu de la biomasse lignocellulosique et reformé pour obtenir de l'hydrogène). La première étape de cette ACV a été effectuée, elle consiste en la définition des objectifs et du champ de l'étude. Deux finalités ont, tout d'abord, été déterminées : - dans un premier temps, la sélection d'une filière énergétique par rapport à ses performances environnementales - dans un second temps, l'amélioration de la filière hydrogène développée par le GEM grâce à l'identification de ses points forts et faibles. Le système « motorisation d'une voiture citadine » a, ensuite, été choisi comme objet de l'étude. L'unité fonctionnelle choisie pour quantifier les performances de ce système est la quantité de carburant consommée pendant toute la durée de vie du système. Le système de référence choisi est le moteur essence puisqu'il s'agit du système présentant les meilleures performances à l'heure actuelle (les filières hydrogène et bioéthanol n'étant qu'au stade de développement). Dès lors, la durée de vie du moteur à explosion est déterminée par 150 000 km parcourus pendant 12 ans. Puis, pour fixer les frontières de chacun des trois systèmes, un arbre des processus ou diagramme de flux a été réalisé, suivi d'un bilan matière et énergie « théorique » pour chaque processus élémentaire (éléments constitutifs du système). Puis en fonction des règles de décisions fixées (selon trois critères masse, énergie et pertinence environnementale), les flux et les processus élémentaires à étudier seront sélectionnés. Pour l'instant, les frontières ont été déterminées pour la filière hydrogène. La deuxième étape de l'ACV a également été entamée, il s'agit de « l'analyse de l'inventaire et les bilans matière et énergie » réalisés à partir des données obtenues expérimentalement pour cette même filière

    How is rape a weapon of war?: feminist international relations, modes of critical explanation and the study of wartime sexual violence

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    Rape is a weapon of war. Establishing this now common claim has been an achievement of feminist scholarship and activism and reveals wartime sexual violence as a social act marked by gendered power. But the consensus that rape is a weapon of war obscures important, and frequently unacknowledged, differences in ways of understanding and explaining it. This article opens these differences to analysis. Drawing on recent debates regarding the philosophy of social science in IR and social theory, it interprets feminist accounts of wartime sexual violence in terms of modes of critical explanation – expansive styles of reasoning that foreground particular actors, mechanisms, reasons and stories in the formulation of research. The idea of a mode of critical explanation is expanded upon through a discussion of the role of three elements (analytical wagers, narrative scripts and normative orientations) which accomplish the theoretical work of modes. Substantive feminist accounts of wartime sexual violence are then differentiated in terms of three modes – of instrumentality, unreason and mythology – which implicitly structure different understandings of how rape might be a weapon of war. These modes shape political and ethical projects and so impact not only on questions of scholarly content but also on the ways in which we attempt to mitigate and abolish war rape. Thinking in terms of feminist modes of critical explanation consequently encourages further work in an unfolding research agenda. It clarifes the ways in which an apparently commonality of position can conceal meaningful disagreements about human action. Exposing these disagreements opens up new possibilities for the analysis of war rape

    Jean Charcot Seabeam Survey along ODP Leg 112 Northern Transect

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    A marine geophysical survey that used Seabeam, multi- and single-channel seismic reflection, gravity, and magnetic profiling was conducted in two locations along the landward slope of the Peru Trench. This survey was conducted during the SeaPERC cruise of the Jean Charcot in July 1986 (Bourgois et al., 1986a; Bourgois et al., 1986b; Bourgois et al., 1987; Bourgois et al., in press). These areas were two possible drilling locations for ODP Leg 112, which was scheduled to begin in November 1986. The drilling transects center around latitudes of 5°30'S and 9°30'S, along multichannel seismic lines CDP-3 and CDP-2, respectively. The northern transect is located in the Paita Zone (Fig. 1, Box 2), and the southern transect is in the Chimbote Zone (Fig. 1, Box 6). During Leg 112, we drilled two sites (683 and 685) in the Chimbote area. This became the northern transect of Leg 112. Here, we report the Seabeam data acquired during the SeaPERC cruise. Drilling results from Sites 683 and 685, the CDP-2 multichannel seismic record, and the Seabeam data provide a threedimensional view of this region

    Tectonic history of the northern Peru convergent margin during the past 400 ka

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    The late Pleistocene tectonic history of the northern Peru convergent margin can be retraced using data collected during deep-sea dives of the submersible Nautile combined with a recent Hydrosweep survey conducted off Peru at lat 5°-6°S by the R/V Sonne. During the past 400 ka, a broad rollover fold formed in the middle slope area, in association with a major seaward-dipping detachment fault. A catastrophic debris avalanche occurred as the result of oversteepening of the landward flank of the rollover fold. The gravity failure of the slope, previously recognized by SeaBeam mapping, occurred at 13.8 ±2.7 ka and produced a destructive tsunami

    Seabeam and seismic reflection imaging of the tectonic regime of the Andean continental margin off Peru (4°S to 10°S)

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    Suite à une campagne géophysique réalisée au large de la côte du Perou (croisière Seaperc du R/V "Jean Charcot", juillet 1986), les auteurs proposent une nouvelle interprétation des structures caractérisant la pente continentale de la région étudiée. D'autre part, ils considèrent que cette marge active est une marge active en extension ou bien une marge d'effondrement qui développe un complexe d'accrétion induit par les effondrements de la partie médiane de la pente
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