Hygrothermal behavior modeling of different Lime-Hemp Concrete mixes

Conference (2013, May 27)

This paper studies the specific hygrothermal behavior of Lime-Hemp concretes through analysis of non-linear coupled heat and moisture transfer using a research model. Three compositions were studied ... [more ▼]

This paper studies the specific hygrothermal behavior of Lime-Hemp concretes through analysis of non-linear coupled heat and moisture transfer using a research model. Three compositions were studied, varying the type of binder. First Moisture Buffer Value determination tests are lead experimentally using the NORDTEST protocol. These dynamic experiments, which reveal the moisture storage and exchange capacity together with latent heat effects, are then modeled using a set of partial differential equations. The reduction of humidity buffering capacity induced by hydraulic binder incorporation is properly evaluated and the hygrothermal parameters can be assessed by inverse modeling. [less ▲]

Blattmaske. Figure du rinceau peuplé dans les mosaïques d'Asie Mineure

Scientific conference (2013, May 25)

Expliquer et illustrer Prospéro. Suivre le marqueur temporel "le-pire-est-à-venir" au sein des agendas politiques climatiques belges (1980-2012)

Conference (2013, May 24)

Introduction

Conference (2013, May 23)

La Bibliothèque miroir : Gabriel Naudé et le libertinage érudit

Doctoral thesis (2013)

Cette thèse est centrée sur la figure de Gabriel Naudé, l’auteur d’un Avis pour dresser une bibliothèque (1627, 1644). Comme ce traité reflète tant la doctrine politique de l’auteur que sa vision sur le ... [more ▼]

Cette thèse est centrée sur la figure de Gabriel Naudé, l’auteur d’un Avis pour dresser une bibliothèque (1627, 1644). Comme ce traité reflète tant la doctrine politique de l’auteur que sa vision sur le savoir, le texte constitue le point de départ pour une analyse détaillée de l’œuvre de l’auteur. Il importe en effet de resituer la pensée de Naudé dans le courant très complexe du libertinage érudit. En soi, les idées de Naudé concernant la bibliothèque ne sont effectivement pas novatrices. Ce constat s’impose comme une évidence lorsque l’opuscule est réinséré dans son contexte. Il s’avère que le bibliothécaire expose d’une manière concise des idées largement répandues, qui rejoignent les préoccupations de la République des lettres. La bibliothèque naudéenne épouse l’irénisme de la communauté intellectuelle et se veut accessible au public. Cette conception très ouverte pose de front le problème de la relation des libertins avec le pouvoir. Dans une France rongée par les guerres de religion et d’incessantes révoltes populaires, Naudé a lié son sort au régime absolutiste, qui était seul à pouvoir garantir la stabilité nécessaire au bonheur commun. Pourtant, Naudé démystifie impitoyablement les mécanismes d’un état qui utilise la religion pour mieux gouverner les âmes. Son œuvre possède donc un potentiel subversif important, qui s’explique par des motifs sociologiques. C’est que Naudé revendique sa place dans la société en tant qu’intellectuel, comme la théorie du jeu permet de le démontrer. En ce qui concerne le contenu de la bibliothèque, il s’agit clairement d’une bibliothèque docte, qui embrasse tous les domaines du savoir. Si Naudé accueillit les hypothèses non prouvées, il reste très attaché aux bases solides de la tradition. Toutefois, pour lui, l’érudition doit être éclairée par les lumières de la raison, ce qui implique que le savoir est soumis à l’exigence de l’efficacité. La vraie connaissance ne s’embarrasse pas de détails inutiles. Le lettré se concentre sur les aspects réellement porteurs de progrès, au lieu de verser dans un esthétisme inutile. D’ailleurs, le véritable savoir ne s’enferme pas dans une tour d’ivoire, mais s’intègre dans la vie civile. La méthode d’analyse de Naudé est philologique. Le libertin préfère la profondeur érudite à l’empirie, comme le montre clairement sa manière d’appréhender la médecine. Pourtant, il ne s’intéresse pas davantage à l’analyse de textes qu’aux sciences naturelles. En réalité, la pensée de Naudé est une pensée métaréflexive, définissant les caractéristiques de l’esprit fort. Le bibliothécaire crée les conditions de possibilité pour l’avancement du savoir, mais s’abstient de produire des travaux d’envergure lui-même. C’est cette conception qui préside à la bibliothèque naudéenne : il s’agit d’un lieu de développement du savoir, dont tous les aspects sont soumis au paradigme de l’utilité. Cette logique s’applique à toutes les composantes de la collection. De fait, les objets non livresques que Naudé intègre dans sa bibliothèque s’avèrent très fonctionnels. [less ▲]

MOA-2010-BLG-311: A planetary candidate below the threshold of reliable detection

in Astrophysical Journal (2013), 769(1), 77

We analyze MOA-2010-BLG-311, a high magnification (A_max>600) microlensing event with complete data coverage over the peak, making it very sensitive to planetary signals. We fit this event with both a ... [more ▼]

We analyze MOA-2010-BLG-311, a high magnification (A_max>600) microlensing event with complete data coverage over the peak, making it very sensitive to planetary signals. We fit this event with both a point lens and a 2-body lens model and find that the 2-body lens model is a better fit but with only Delta chi^2~140. The preferred mass ratio between the lens star and its companion is $q=10^(-3.7+/-0.1), placing the candidate companion in the planetary regime. Despite the formal significance of the planet, we show that because of systematics in the data the evidence for a planetary companion to the lens is too tenuous to claim a secure detection. When combined with analyses of other high-magnification events, this event helps empirically define the threshold for reliable planet detection in high-magnification events, which remains an open question. [less ▲]

Poetry and Silent Films

Conference (2013, May 17)

La structuration du monde paysan au Rwanda : cas des coopératives et des stations de lavage de café de Maraba et de Karaba, District de Huye

Doctoral thesis (2013)

The agricultural sector is the main economic activity of Rwanda, which occupies approximately 90% of the active population in rural areas. It contributes more than 36% to the GDP. Coffee is the main cash ... [more ▼]

The agricultural sector is the main economic activity of Rwanda, which occupies approximately 90% of the active population in rural areas. It contributes more than 36% to the GDP. Coffee is the main cash crop and source of income for farmers, and provides major currencies for the national economy. Although it covers only 6.3% of cultivated areas, coffee is produced by 500,000 households in Rwanda. Since its introduction in the country in 1904, coffee has always been operated by individual producers. After the liberalization of the coffee sector in Rwanda in 1998, the quantity and quality produced are steadily decreasing which affects the price and the income of coffee growers. In the search for a solution to this problem, the Rwandan government has focused on the consolidation of producers cooperatives, and on the building of coffee washing stations (CWS) in all coffee growing areas at national level. The goal is to produce a fully washed coffee, exportable and better valued on the international market, which can provide better income for peasant producers. Washing stations are then seen as tools to produce quality coffee and are mainly run by cooperatives, which are structural elements in the rural world. Survey work on a sample of 80 farms for the three seasons (2008, 2009, 2010) as well as interviews with various key agents involved in the coffee sector have been conducted to understand and analyze the effects of CWS and cooperatives on coffee growers. This original dissertation is devoted to analyze the impact resulting from the structure action of the peasant world through cooperatives and coffee washing stations of Maraba and Karaba in southern Rwanda, on the socio-economic development of farmers who are members of a cooperative and the surrounding world by comparing to non-members of cooperatives. Through these facilities and structures put in place, jobs are created for producers, farmers are motivated due to income increases, the market is guaranteed, the prices are higher for members and loans are given, thereby improving the socio-economic and technical assistance to growers, which reduces the poverty among coffee growers’ households. [less ▲]

Laboratory demonstration of a mid-infrared AGPM vector vortex coronagraph

in Astronomy and Astrophysics (2013), 553

Coronagraphy is a powerful technique to achieve high contrast imaging and hence to image faint companions around bright targets. Various concepts have been used in the visible and near-infrared regimes ... [more ▼]

Coronagraphy is a powerful technique to achieve high contrast imaging and hence to image faint companions around bright targets. Various concepts have been used in the visible and near-infrared regimes, while coronagraphic applications in the mid-infrared remain nowadays largely unexplored. Vector vortex phase masks based on concentric subwavelength gratings show great promise for such applications. We aim at producing and validating the first high-performance broadband focal plane phase mask coronagraphs for applications in the mid-infrared regime, and in particular the L band with a fractional bandwidth of ~16% (3.5-4.1 \mu m). Based on rigorous coupled wave analysis, we designed an annular groove phase mask (AGPM) producing a vortex effect in the L band, and etched it onto a series of diamond substrates. The grating parameters were measured by means of scanning electron microscopy. The resulting components were then tested on a mid-infrared coronagraphic test bench. A broadband raw null depth of 2 x 10^{-3} was obtained for our best L-band AGPM after only a few iterations between design and manufacturing. This corresponds to a raw contrast of about 6 x 10^{-5} (10.5 mag) at 2\lambda/D. This result is fully in line with our projections based on rigorous coupled wave analysis modeling, using the measured grating parameters. The sensitivity to tilt and focus has also been evaluated. After years of technological developments, mid-infrared vector vortex coronagraphs finally become a reality and live up to our expectations. Based on their measured performance, our L-band AGPMs are now ready to open a new parameter space in exoplanet imaging at major ground-based observatories. [less ▲]

Nonimaging achromatic shaped Fresnel lenses for ultrahigh solar concentration

in Optics Letters (2013), 38(10), 1730-1732

The maximum concentration ratio achievable with a solar concentrator made of a single refractive primary optics is much more limited by the chromatic aberration than by any other aberration. Therefore ... [more ▼]

The maximum concentration ratio achievable with a solar concentrator made of a single refractive primary optics is much more limited by the chromatic aberration than by any other aberration. Therefore achromatic doublets made with poly(methyl methacrylate) and polycarbonate are of great interest to enhance the concentration ratio and to achieve a spectrally uniform flux on the receiver. In this Letter, shaped achromatic Fresnel lenses are investigated. One lossless design is of high interest since it provides spectrally and spatially uniform flux without being affected by soiling problems. With this design an optical concentration ratio of about 8500× can be achieved. [less ▲]