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See detailLes jeunes et le génocide des Juifs : analyse socio-politique
Grandjean, Geoffrey ULg

Book published by De Boeck (2014)

La mémoire du génocide des Juifs est très présente dans les sociétés occidentales à travers des vecteurs de socialisation comme l’école, les médias, la famille, et plus récemment les réseaux sociaux et ... [more ▼]

La mémoire du génocide des Juifs est très présente dans les sociétés occidentales à travers des vecteurs de socialisation comme l’école, les médias, la famille, et plus récemment les réseaux sociaux et Internet. Quelles peuvent être les conséquences de la transmission de cette mémoire sur le développement des attitudes et des comportements politiques des jeunes ? C’est la question centrale de l’ouvrage qui présente les connaissances, les émotions et les valeurs mobilisées par les jeunes dans le cadre de groupes de discussion, et qui surtout les met en perspective avec leurs représentations et leurs perceptions des autorités politiques. Au final, plusieurs questions difficiles pour le futur émergent. En effet, à bien des égards, l’impact de la transmission de la mémoire du génocide des Juifs sur la socialisation politique des jeunes pose la question de l’éventualité de sa répétition, de son caractère exceptionnel, de sa compréhension, ou encore de l’effacement de sa mémoire dans la dynamique des générations et du temps qui passe. [less ▲]

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See detailThe last Neanderthals in North-West Europe and the Lincombian-Ranisian-Jerzmanowician
Flas, Damien ULg

Conference (2014, March 21)

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Peer Reviewed
See detailNew fossils at the “Troisième caverne” of Goyet (Belgium) and the mortuary practices of late Neandertals
Rougier, H.; Crevecoeur, I.; Beauval, C. et al

Conference (2014, March 21)

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Peer Reviewed
See detailInsight into the ecology of Neandertals in North-West Europe: stable isotopes and their palaeobiological implications
Wissing, C.; Bocherens, H.; Crevecoeur, I. et al

Conference (2014, March 21)

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See detailAn analysis of access to credit by animal producing households in Hai Duong Province, Vietnam
Le Thi Minh, Chau ULg

Doctoral thesis (2014)

In a context of increasing demand for meat and fish, the animal production sector is seen as a driver of growth for agriculture in Hai Duong Province, Vietnam. However, the growth prospects of this sector ... [more ▼]

In a context of increasing demand for meat and fish, the animal production sector is seen as a driver of growth for agriculture in Hai Duong Province, Vietnam. However, the growth prospects of this sector seem undermined by a limited credit supply. This study aims to explore access to credit by animal producing households, factors affecting their credit accessibility and the influence of credit and non-credit factors on animal production. The study results show that all households surveyed, both the animal-based group and the non animal-based group, need credit for both production activities and consumption. The formal sector, which for the most part provides credit for production activities, did not meet the credit needs of the animal producers. Thus, only 52% of surveyed households applied to commercial banks for credit, the remaining households felt that they had no chance of receiving loans. Looking at the household characteristics as the center for analysis, it was found that physical collateral, the area of the fish pond and social relationships positively affected the probability of credit access by animal producing households. In addition, the area of the fish pond, number of laborers, share of income from animal production and social relationships positively affected the borrowing amount that was approved by commercial banks. Among animal producing households, the poor households likely had a lower probability of credit access and lower borrowing amounts than the non-poor households. The credit needs of farmers were often more rationed by commercial banks. Furthermore, some weaknesses of the rural lending apparatus in Hai Duong Province impeded access to credit by households. The credit constrained households accounted overall for 71% of the households surveyed. On the other hand, both the animal-based group and the animal-based group also suffered from some non-credit constraints relating to production and marketing. Within each group, the non-credit constraints caused a similar negative influence on animal production income, relatively speaking. Credit accessibility was different among households. As a result, for a given production unit, credit constrained households generated less income than non-credit constrained households. Improving the credit supply and some non-credit factors is expected to increase income from animal production. The study mainly suggests that the local authorities should support small-scale animal producers to establish animal producer groups to overcome constraints to credit access, production and marketing. Besides strengthening the credit supply to individual borrowers, the formal sector should grant feed purchase credit vouchers to animal producing groups. [less ▲]

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See detailProduction, transformation artisanale et commercialisation locale des produits alimentaires traditionnels au Vietnam: le cas du vermicelle de tolomane à Hung Yen
Le, Thi Long Vy ULg

Doctoral thesis (2014)

In Vietnam, the vermicelli of Canna edulis Ker Gawl. (C. indica L.) is an artisanal and traditional product, regularly consumed in the festive occasions. From Canna edulis Ker Gawl cultivation to trading ... [more ▼]

In Vietnam, the vermicelli of Canna edulis Ker Gawl. (C. indica L.) is an artisanal and traditional product, regularly consumed in the festive occasions. From Canna edulis Ker Gawl cultivation to trading of vermicelli of Canna edulis at the local level, the vermicelli commodity chain belongs to peasant economy with many actors involved. This research aims at a better understanding of how the actors of vermicelli commodity chain adapt to current socio-economic and environmental conditions of the villages which belong to two communes (Tu Dan and Yen Phu) located in Hung Yen Province. The surveys among 90 farmers and discussions with a group of producers who cultivate the canna and practice flour processing, and a group of vermicelli processors have been carried out from 2010 to 2012. According to our research results, vermicelli commodity chain has created a considerable additional quantity of jobs for local people within the villages of vermicelli processing and the neighboring ones. Thanks to these activities, the rural households income and production investment have been increased. Net income estimated per hectare of canna is about 22.2 million VND (about 822 €), and nearly 4.5 million VND (167 €) per ton of flour produced, and up to 1.7 million VND per ton of vermicelli product (about 63 €). In addition, these activities allow to diversify the sources of family incomes in the countryside. These activities also contribute to stabilize and increase the living standard of farmers (in 2010, the net family income (NFI) due to canna production accounted for 8% to 34 % of farming income; the NFI of vermicelli processing represented between 35% and 86 % of total processing family income). The value-added generated from this vermicelli commodity chain is important, up to 186 million VND (about 7,900 €) per hectare of canna, in which 38 % for flour processing; 20% for vermicelli processing and 20 % for canna cultivators. Thus, the vermicelli commodity chain contributes to meet a specific demand for traditional food in Vietnam. This chain contributes to the rural economy of traditional villages through improving the sources of familial income. However, it is necessary to increase the product quality and to improve the vertical and horizontal linkages between the actors in order to guarantee the sustainable development of this vermicelli chain. [less ▲]

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See detailConcurrence mémorielle, interculturalité, multiculturalité et transculturalité
Grandjean, Geoffrey ULg

Conference given outside the academic context (2014)

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See detailLes enseignants à l'image. Représentations iconographiques et audiovisuelles du mouvement enseignant (1995-1996)
Lanneau, Catherine ULg

Conference (2014, March 20)

Les réformes institutionnelles de 1988-1989 ont transféré aux Communautés les compétences en matière d’enseignement. Pour la Communauté française, cette responsabilisation a très vite rimé avec la ... [more ▼]

Les réformes institutionnelles de 1988-1989 ont transféré aux Communautés les compétences en matière d’enseignement. Pour la Communauté française, cette responsabilisation a très vite rimé avec la nécessité de réaliser d’importantes économies et donc d’importantes réformes structurelles. Une première vague de protestation secoue Bruxelles et la Wallonie en 1990 mais, cinq ans plus tard, un nouveau plan d’économies préparé par la socialiste Laurette Onkelinx, Ministre-Présidente de la Communauté française, en charge notamment de l’Education, donne naissance à un long et douloureux mouvement de protestation. Celui-ci semble matérialiser la rupture entre une base enseignante proche, selon les réseaux, du PS ou du PSC, et un Exécutif au sein duquel ces deux partis fonctionnent en coalition. Réduction des dépenses, suppression de trois mille postes, fusions d’écoles, tous les ingrédients sont réunis pour que la situation soit explosive. Elle va l’être d’autant plus – et cela marquera d’ailleurs durablement les esprits – que certaines manifestations de mécontentement vont s’exprimer avec violence, s’attaquer à des symboliques fortes (la Fête de la Communauté française en septembre 1995, le 1er mai 1996) et perturber la vie privée de la Ministre et de son entourage. Notre contribution s’inscrit dans le volet « images produites ». Elle s’interrogera sur le rôle des images dans la représentation que la presse écrite généraliste a donnée du mouvement enseignant et des enseignants eux-mêmes durant ce conflit. Grâce à certaines archives numérisées, le traitement du mouvement par l’audiovisuel public pourra, lui aussi, être abordé. La photographie de presse, la caricature et le reportage ont-ils contribué à présenter le mouvement enseignant de manière objective et dépassionnée ? Ont-ils au contraire – et jusqu’à quel point ? - intégré les clichés traditionnels véhiculés sur cette catégorie socio-professionnelle (conservatisme, attachement à de supposés « privilèges »…). Quelle image est renvoyée du syndicalisme enseignant ? Comment est mise en scène la relation triangulaire entre grévistes, ministre et public de l’école (parents et élèves) ? Quels sont le poids et le rôle dévolus à chacun ? Quelle est, spécifiquement, le traitement réservé au mouvement par un journal comme La Wallonie ? Comment a-t-il accompagné en images la rupture entre le monde enseignant, la CGSP et le parti socialiste, culminant le 1er mai 1996 ? [less ▲]

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See detailLe suivi des enfants nés prématurés ou avec un très petit poids de naissance : le projet CAP48
Mostaert, Anne; Nassogne, Marie-Cécile; Vermeylen, Danièle et al

Poster (2014, March 20)

This poster describes the cohort of very preterm and very low birth weight newborns recruted in the "CAP48" project and anaylses the main reasons for cessation of follow-up.

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See detailMénages ruraux et lutte contre la pauvreté : cas des communes de Tu Ly et de Xuang Phong dans la province de Hao Binh Viet Nam
Mai, Lan Phuong ULg

Doctoral thesis (2014)

Since 1998, Viet Nam developed many poverty reduction strategies with the assistance of the WB and the IMF. However, although the national rate of poverty decreased in absolute terms, it does not reflect ... [more ▼]

Since 1998, Viet Nam developed many poverty reduction strategies with the assistance of the WB and the IMF. However, although the national rate of poverty decreased in absolute terms, it does not reflect a real reduction in poverty and does not take into account the nature of poverty. Income and opportunities inequality increased between urban and rural areas, between different social classes and between the Kinh (majority group in Viet Nam) and ethnic minorities. Poverty of ethnic minorities has become an ongoing challenge. In 2010, there were 66.3% of the poor among ethnic minorities against only 12.9% for the Kinh population. This thesis illustrates a reflection on the issue of poverty in Viet Nam and in particular mountainous northern regions where the poverty rate is the highest, reaching 39.4 % in 2012. The historical approach, the capacity approach, the descriptive statistical analysis and case analysis are used to conduct this research. The first difficulty is the identification of poor households and beneficiaries of poverty reduction strategies. Other difficulties are disclosed by the analysis of strategies against poverty: information confusion, budget limitation, insufficient participation of local people in program planning and monitoring, limited autonomy at the local level. Finally it appears that strategies against poverty are not efficient. In addition, land resource privatization, particularly forest resources, limits minority farmers’ ability to cope with unexpected risks Faced with this situation, a possible solution could be to strengthen the role of farmers' associations. Taking into account the ideas and initiatives of local actor, driven by farmers' associations, would have a positive impact on the poverty reduction strategy. Donations and subsidies to individuals should no longer be practiced. In the present threatening world, solidarity among small farmers is necessary to enable them to find their place in the production system and keep the justified profits. In the long run, it is better to give financial support to assist groups and support initiatives by associations of small farmers to facilitate their participation in the market economy while improving their well-being. [less ▲]

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See detailmaking the most of the LBTI nulling interferometry observations using a statistical data reduction method
Marion, Lindsay ULg; Mennesson, Bertrand; Defrère, Denis et al

Poster (2014, March 20)

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See detailChildren’s perspectives on their working lives and on public action against child labour in Burkina Faso
Wouango, Joséphine ULg

Conference (2014, March 20)

Since the end of 1990’s, there has been a growing interest to combat child labour in Burkina Faso. State actors as well as civil society organisations have started to engage themselves to urgently combat ... [more ▼]

Since the end of 1990’s, there has been a growing interest to combat child labour in Burkina Faso. State actors as well as civil society organisations have started to engage themselves to urgently combat the worst forms of child labour. The 2006 National Statistical Survey found that 41.1 % of children aged 5 to 17 years were economically active. Compared to other West African countries, Burkina Faso is said to have the highest rate of children involved in hazardous work, which is one working child out of two. In this context of renewed interest regarding child labour, working children have their say. Based on a qualitative survey, this paper is focused on the perspectives of children working in two of the eleven hazardous sectors of activity identified by the 2009 National Decree: a stone quarry located in the capital Ouagadougou and an artisanal gold mine in a northern rural area. The paper aims to better understand the experience and opinions of children at work, to describe what work means to them, the role and the benefits of work in their lives and the difficulties they encounter. The focus is also on what children (and their families) think about public action against child labour and what are their aspirations regarding the current interventions. The analysis shows that if economic reasons lead children to work in in these two sectors of activity, this not the only determinant. The wish of a large number of children (and their parents) to find other less difficult work reopens the debate on children’s right to work. The results of this study reveal that there is a need to better understand how working children and their fmailies negotiate everyday life within the socio-cultural and economic context of Burkina Faso. [less ▲]

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See detailL’ambition climatique de l’Europe est aussi socio-économique
Chapelle, Grégor; de Borchgraeve, François; de Callataÿ, Etienne et al

Article for general public (2014)

Les objectifs climatiques et énergétiques de la Commission européenne sont trop faibles. Inquiets, plusieurs chefs d’entreprises et académiques demandent à notre Premier ministre de plaider, lors du ... [more ▼]

Les objectifs climatiques et énergétiques de la Commission européenne sont trop faibles. Inquiets, plusieurs chefs d’entreprises et académiques demandent à notre Premier ministre de plaider, lors du Conseil européen, pour une politique climat-énergie bien plus ambitieuse. [less ▲]

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See detailLa résilience chez les plus vulnérables au Rwanda
Militery Ngamata, Olivier ULg

Doctoral thesis (2014)

After the tragedy of the genocide against Tutsi in 1994, the Rwandan Government has developed and implemented different programmes and interventions in the sector of social protection in order to reduce ... [more ▼]

After the tragedy of the genocide against Tutsi in 1994, the Rwandan Government has developed and implemented different programmes and interventions in the sector of social protection in order to reduce the poverty of the vulnerable populations and so reach the Millennium Development Goals (MDGs). The different interventions done in the context of social security of the poor people are considered as means of increasing the economy, integrating people in employment market, improving human development thanks to a better access to health and education, and reducing poverty. After the context and justification of the research as well as the methods for data collection, this study focuses primarily on the conceptualization of resilience and connected concepts. Secondly, it scrutinizes the impact of the three programmes of social protection that were developed to reduce poverty of the beneficiaries. The first programme is FARG that supports the survivors of the 1994 genocide against the Tutsi in the domain of education, access to accommodation, medical health and income generating activities. The second programme is Ubudehe-VUP-2020. This one helps very poor households via direct financial transfers, creation of jobs and access to financial services. Girinka is the third programme; it contributes to food improvement, subsistence means and land fertility by supplying a dairy cow to poor families. In third position, this research assesses the achievements of the association of the widows survivors of genocide called - Agahozo (AVEGA) as well as the successes so far reached by the widows beneficiaries. The widows consider AVEGA as an important ‘tutor for resilience’ because it not only deals with their psychological aspects related to the tragedies they experienced but also the promotion and development of economic activities that can supply them with an income for their social reintegration at both economic and social levels. Thus, AVEGA involves a diversity of actors in order to help the widows and implement various income generating activities. Research conducted on the field has targeted, in last position, the most resilient widows. These widows have got support from social protection programmes and AVEGA, in order to involve in income generating activities among which the most developed are agriculture, animal rearing and commerce. All in all, the widows of genocide who were surveyed positively commented the support they get from SPP and AVEGA regarding the reinforcement of their economic resilience. [less ▲]

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See detailContribution à l'amélioration de l'accès à une eau potable de qualité pour les populations de la région nord du Burkina Faso
Some, Issam; Guel, Boubié; Hantson, Anne-Lise et al

Poster (2014, March 19)

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See detailAudiovisual spatial congruence, and applications to 3D sound and stereoscopic video
André, Cédric ULg

Doctoral thesis (2014)

While 3D cinema is becoming increasingly established, little effort has focused on the general problem of producing a 3D sound scene spatially coherent with the visual content of a stereoscopic-3D (s-3D ... [more ▼]

While 3D cinema is becoming increasingly established, little effort has focused on the general problem of producing a 3D sound scene spatially coherent with the visual content of a stereoscopic-3D (s-3D) movie. The perceptual relevance of such spatial audiovisual coherence is of significant interest. In this thesis, we investigate the possibility of adding spatially accurate sound rendering to regular s-3D cinema. Our goal is to provide a perceptually matched sound source at the position of every object producing sound in the visual scene. We examine and contribute to the understanding of the usefulness and the feasibility of this combination. By usefulness, we mean that the technology should positively contribute to the experience, and in particular to the storytelling. In order to carry out experiments proving the usefulness, it is necessary to have an appropriate s-3D movie and its corresponding 3D audio soundtrack. We first present the procedure followed to obtain this joint 3D video and audio content from an existing animated s-3D movie, problems encountered, and some of the solutions employed. Second, as s-3D cinema aims at providing the spectator with a strong impression of being part of the movie (sense of presence), we investigate the impact of the spatial rendering quality of the soundtrack on the reported sense of presence. The short 3D audiovisual content is presented with three different soundtracks. These soundtracks differ by their spatial rendering quality, from stereo (low spatial coherence) to Wave Field Synthesis (WFS, high spatial coherence). The original stereo version serves as a reference. Results show that the sound condition does not impact on the sense of presence of all participants. However, participants can be classified according to three different levels of presence sensitivity with the sound condition impacting only on the highest level (12 out of 33 participants). Within this group, the spatially coherent soundtrack provides a lower reported sense of presence than the other custom soundtrack. The analysis of the participants' heart rate variability (HRV) shows that the frequency-domain parameters correlate to the reported presence scores. By feasibility, we mean that a large portion of the spectators in the audience should benefit from this new technology. In this thesis, we explain why the combination of accurate sound positioning and stereoscopic-3D images can lead to an incongruence between the sound and the image for multiple spectators. Then, we adapt to s-3D viewing a method originally proposed for 2D images in the literature to reduce this error. Finally, a subjective experiment is carried out to prove the efficiency of the method. In this experiment, an angular error between an s-3D video and a spatially accurate sound reproduced through WFS is simulated. The psychometric curve is measured with the method of constant stimuli, and the threshold for bimodal integration is estimated. The impact of the presence of background noise is also investigated. A comparison is made between the case without any background noise and the case with an SNR of 4 dBA. Estimates of the thresholds and the slopes, as well as their confidence intervals, are obtained for each level of background noise. When background noise is present, the point of subjective equality (PSE) is higher (19.4° instead of 18.3°) and the slope is steeper (-0.077 instead of -0.062 per degree). Because of the overlap between the confidence intervals, however, it is not possible to statistically differentiate between the two levels of noise. The implications for the sound reproduction in a cinema theater are discussed. [less ▲]

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See detailArtificial Abelian gauge potentials induced by dipole-dipole interactions between Rydberg atoms
Cesa, Alexandre ULg; Martin, John ULg

Poster (2014, March 19)

We analyze the influence of dipole-dipole interactions between Rydberg atoms on the generation of Abelian artificial gauge potentials and fields. When two Rydberg atoms are driven by a uniform laser field ... [more ▼]

We analyze the influence of dipole-dipole interactions between Rydberg atoms on the generation of Abelian artificial gauge potentials and fields. When two Rydberg atoms are driven by a uniform laser field, we show that the combined atom-atom and atom-field interactions give rise to nonuniform, artificial gauge potentials. We identify the mechanism responsible for the emergence of these gauge potentials. Analytical expressions for the latter indicate that the strongest artificial magnetic fields are reached in the regime intermediate between the dipole blockade regime and the regime in which the atoms are sufficiently far apart such that atom-light interaction dominates over atom-atom interactions. We discuss the differences and similarities of artificial gauge fields originating from resonant dipole-dipole and van der Waals interactions. We also give an estimation of experimentally attainable artificial magnetic fields resulting from this mechanism and we discuss their detection through the deflection of the atomic motion. [less ▲]

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See detailEtude des possibilités de culture de Jatropha curcas L. dans la région de Kinshasa en République Démocratique du Congo (RDC)
Minengu Mayulu, Jean de Dieu ULg

Doctoral thesis (2014)

Au cours de ces dernières années, des plantations de Jatropha curcas L. ont été mises en place dans de nombreuses régions d’Afrique subsaharienne pour la production d’agrocarburants sans connaissances ... [more ▼]

Au cours de ces dernières années, des plantations de Jatropha curcas L. ont été mises en place dans de nombreuses régions d’Afrique subsaharienne pour la production d’agrocarburants sans connaissances préalables des conditions de rentabilité et des techniques de production les mieux adaptées aux contextes locaux. L’objectif du présent travail est de lever cette lacune pour la région de Kinshasa en apportant des réponses aux principales questions qui conditionnent la mise au point d’un agrosystème durable basé sur la culture de J. curcas. Pour atteindre cet objectif, les performances d’une plantation pilote installée à proximité de la cité de Mbankana en décembre 2007 ont été évaluées et quatre essais ont été réalisés à partir de juillet 2009 à janvier 2013 dans deux sites représentatifs des conditions du Plateau des Batéké (Mbankana et Mongata) et à proximité de la rivière N’sele dans la banlieue de Kinshasa. Les résultats obtenus montrent que les facteurs de l’environnement et les pratiques culturales ont une influence sur le rendement en graines et en huile de J. curcas. Les faibles rendements obtenus, le coût très élevé des intrants (engrais et insecticides) et les faibles quantités de graines récoltées par journée de travail sont les principales causes de l’absence de rentabilité de la culture pure de J. curcas dans les premières plantations mises en place avec du matériel végétal local subspontané. Les principaux insectes ravageurs de J. curcas dans la zone d’étude sont les grillons Brachytrupes membranaceus Drury (Orthoptera, Grillidae) qui s’attaquent aux jeunes plantes lors de leur mise en place en saison pluvieuse (octobre à décembre), les chenilles mineuses de feuilles Stomphastis thraustica Meyrick (Lepidoptera, Gracillariidae), les chrysomèles Aphthona sp. (Coleoptera, Chrysomelidae) qui consomment le limbe des feuilles et les bourgeons, ainsi que les punaises à bouclier Calidea sp. (Heteroptera, Scutelleridae) qui causent des dégâts aux fleurs et aux capsules. Parmi ceux-ci, la chrysomèle est pour l’instant le ravageur le plus dommageable. En l’absence de traitements insecticides, le niveau des pertes de rendement occasionnées par ces insectes ravageurs atteignent 90% en culture pure sur le Plateau des Batéké. La gravité des dégâts des insectes ravageurs sur J. curcas est plus élevée en culture pure (>60%) que quand il est associé à d’autres cultures annuelles (<45%). La mise au point de méthodes durables de contrôle des ravageurs est une des conditions indispensables à l’installation de plantations de J. curcas dans la région de Kinshasa. L’application de la taille, de la fertilisation minérale et de la couverture du sol avec Stylosanthes guianensis (Aublet) Swartz, permet d’améliorer significativement le rendement en graines de J. curcas Onze écotypes de J. curcas, collectés dans les différentes régions de la RDC et mis en culture au Plateau des Batéké, ont montré des différences significatives en termes du développement végétatif et des rendements en graines et en huile. Le rendement moyen obtenu en 3eme année de production par l’écotype le plus productif (Panu : 473,1±3,6 kg de graines sèches ha-1) était près de 7 fois plus élevé que le rendement de l’écotype qui a produit le moins (Ilebo : 68,6±3,6 kg ha-1). Contrairement à ce qui était annoncé dans la littérature, le temps nécessaire pour l’entrée en pleine production de J. curcas en conditions tropicales humides est supérieur à 5 ans. Il n'est pas possible de déterminer sur base de nos résultats, le niveau exact de rendement qui sera obtenu quand les plantes entreront en pleine production. Quel que soit celui-ci, le coût très élevé de la main d’œuvre nécessaire à la collecte des graines de J. curcas et au désherbage limite fortement les perspectives de rentabilité de la culture pure dans la région de Kinshasa. Dans les zones enclavées du pays, où le coût de la main d’œuvre est moindre et où le prix du diesel est plus élevé, la production de J. curcas peut constituer l’une des solutions pour résoudre les problèmes d’accès à l’énergie. [less ▲]

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See detailImpact des matériaux biosourcés sur le climat intérieur : Un outil de calcul flexible à l'échelle de la pièce
Dubois, Samuel ULg; Lebeau, Frédéric ULg

Conference (2014, March 19)

L'impact de l'utilisation de matériaux d'origine végétale sur le climat intérieur, et donc sur le confort des occupants ainsi que la performance énergétique du bâtiment, n'est établi que partiellement ... [more ▼]

L'impact de l'utilisation de matériaux d'origine végétale sur le climat intérieur, et donc sur le confort des occupants ainsi que la performance énergétique du bâtiment, n'est établi que partiellement. Ces produits présentent des propriétés hygroscopiques et capillaires causant des phénomènes spécifiques liés aux changements de phase dynamiques au sein de la matrice poreuse. Les modèles mathématiques utilisés pour étudier leur comportement hygrothermique de manière détaillée sont souvent des modèles de paroi (dits modèles HAM - Heat Air Moisture). Cela sous-tend qu'ils nécessitent d'imposer des conditions aux limites à toutes les frontières de l'élément étudié, et ne permettent donc pas de connaître les flux de chaleur et de masse réels qu'offrent l'assemblage de matériaux vers le volume d'air intérieur. Pour y accéder, il convient d'intégrer ces modèles à la description de bilans thermique et hydrique de zones. Dans cette communication, nous présentons un modèle hygrothermique capable de simuler l'évolution temporelle du climat intérieur d'une ou de plusieurs pièces ("zones thermiques"). Il est composé d'un module HAM basé sur des équations aux dérivées partielles et caractérisant les transferts dans les matériaux de construction et développé au sein de l'environnement numérique COMSOL Multiphysics. Les équations qui le composent sont flexibles et facilement adaptables au cas expérimental modélisé ainsi qu'aux propriétés des matériaux composant les parois. En outre, on y trouve un traitement complet des phénomènes de changement de phase qui prend en compte l'impact de la température sur la capacité de stockage d'humidité du matériau. Ce premier module, est couplé à un outil caractérisant les bilans chaleur/masse au niveau de la zone à l'aide d'équations aux dérivées ordinaires. Le couplage des modèles est effectué au sein de SIMULINK, un outil de MATLAB destiné à l'étude des systèmes dynamiques. Nous appliquons ensuite ce modèle à l'étude d'un mur en ballots de paille séparant une enceinte climatique de grande taille en deux volumes d'air. Les données d'une expérience simple, un choc thermique imposé à un des volumes d'air, sont comparées aux sorties du modèle numérique. [less ▲]

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