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See detailModélisation spatiale des flux organiques et minéraux assurant la productivité durable des agroécosystèmes culture-élevage dans le sahel nigérien
Djaby, Bakary ULg

Doctoral thesis (2010)

Agriculture (including crop and livestock) employs more than 80% of the work force in semi-arid regions of West Africa and provide most of the food requirements and incomes. In most developing countries ... [more ▼]

Agriculture (including crop and livestock) employs more than 80% of the work force in semi-arid regions of West Africa and provide most of the food requirements and incomes. In most developing countries, soil nutrient depletion is a major issue for soil degradation. Crop-livestock integration is an effective means by which nutrients can be rapidly recycled within and between farms. In West Niger, where mixed farming systems dominate, livestock's role in recycling organic matter and mineral nutrients (nitrogen, phosphorus and potassium) must be better assessed to increase production and ensure sustainable food security. Nutrient flows through forage uptake and excretion deposit by grazing livestock must be assessed at a wider scale than the farm. Organic matter and nutrients balance and fluxes were used as measurable criteria for sustainable agriculture production. This research focuses on these indicators assessments at farm, land use unit and village level. This study was conducted in three agropastoral territories in the Fakara region of western Niger (Dantiandou District) that lies between the Niger River to the west and the Dallol Boboye (Bosso), a fossil valley tributary of the Niger, to the east. The area has homogeneous geological characteristics and rainfall conditions, but land use history, human and animal population density and cropping intensity vary within the region. 461 farms were concerned. In the mixed crop-livestock systems, the duality of the spatial organization, crop management at field level and livestock management with communal rangeland is a major issue for nutrients balance and fertility management modeling. Two models were then used to assess flows and nutrients balances. The NUTMON Toolbox developed by Dutch researchers is used to assess agricultural fluxes at farm parcels level. Spatial modeling was done with NUTPAST, a GIS tool developed in this thesis framework to assess livestock intake and excretion fluxes at land use scale. This tool takes into account the spatiotemporal patterns of vegetation as well as livestock seasonal variation. Quantile regression analysis and multinomial polytomous logistic regression modeling was used to assess soil fertility depletion risk indicator based on farm agriculture viability variables and nutrients partial balance. The results obtained show a less negative partial nutrients balance than in previous studies when the livestock spatio-temporal effect is taken into account. The results bring functional improvement and analytical evaluation of flows and partial nutrients balance calculation, while taking into account the functions of livestock in the organic matter recycling. The overall partial balance of N, P, K are 0.3 ± 0.6, 1.2 ± 0.2, 0.9 ± 0.5 kg/ha. The review highlighted a wide disparity between farms which show a strongly positive balance among livestock owners and negative balance among Fakara small farmers with few land and livestock endowments. Owning animals allows some households to maintain soil fertility by capturing and mobilizing soil nutrients. Risk indicators, based on land pressure indicator at 3x3 km geographic grid level, livestock endowments and land per capita reveal that despite a slow intensification, the trend for a risk of relative depletion of soil fertility is very high. This trend may compromise the sahelian agriculture sustainability. The problems of unequal benefit from communal resources remain a big issue of the sahelian agriculture. With increasing pressure on land, it is necessary to look beyond the traditional free range communal grazing systems to more intensive alternatives and stronger land tenure policies. [less ▲]

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See detailModélisation spatialement distribuée et physiquement basée d’écoulements hydrologiques et hydrodynamiques pour l’aide à la gestion d’ouvrages hydrauliques
Khuat Duy, Bruno ULg

Doctoral thesis (2011)

La gestion des ressources en eau constitue une préoccupation qui prend une place de plus en plus importante dans nos sociétés. Les événements climatiques extrêmes subis ces dernières années (pluies ... [more ▼]

La gestion des ressources en eau constitue une préoccupation qui prend une place de plus en plus importante dans nos sociétés. Les événements climatiques extrêmes subis ces dernières années (pluies diluviennes mais également sécheresses) montrent toute la nécessité d’une meilleure compréhension des phénomènes en cause afin de mettre en place une gestion efficace des ressources. Ces études passent notamment par le développement de logiciels de simulation basés sur des modèles hydrologiques et hydrodynamiques fiables capables de représenter correctement les phénomènes réels mis en jeu. Cette thèse contribue à la mise en place d’un outil de modélisation spatialement distribuée et physiquement basée d’écoulements hydrologiques et hydrodynamiques, destiné notamment à fournir une aide précieuse pour la gestion d’ouvrages hydrauliques. Chaque composante de modélisation du circuit hydrologique, depuis la pluie jusqu’à l’exutoire de la rivière, est examinée. Des améliorations ou développements plus fondamentaux sont alors proposés pour améliorer la qualité de modélisation. Entre autres, cette thèse aborde en profondeur des sujets tels que la prise en compte de la microtopographie dans la représentation des phénomènes de surface (stockage dans les dépressions, écoulement en ruisselets, relations hauteurs-section-volume…), le calcul de l’infiltration (modèle à fronts multiples, effet de l’occupation du sol…) ou l’écoulement dans la couche hypodermique (écoulement saturé/non saturé, mise en pression…). Les recherches et développements portent également sur l’écoulement dans les axes de concentration (création d’un réseau de rivières cohérent à la fois avec le modèle numérique de terrain et les levés précis sur site, exploitation adéquate des données de section, modélisation efficace des ouvrages en charge ou non…). La modélisation des surfaces imperméables (avec séparation des zones égouttées ou non) est également abordée de façon détaillée, dans le cadre d’une application sur un bassin versant instrumenté de 130 km². Cette application envisage aussi bien la modélisation d’un événement ponctuel que des simulations à long terme. Enfin, l’étude d’un bassin peu instrumenté permet de montrer la large applicabilité et sa capacité à servir de support efficace dans la gestion des rivières et des ouvrages hydrauliques associés. [less ▲]

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See detailModélisation tridimensionnelle de fragments urbains par voie photogrammétrique
Ernst, Julien ULg

Master's dissertation (2006)

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See detailModélisation tridimensionnelle du transport sédimentaire au large de la côte belge
Mercier, Christophe ULg

Master of advanced studies dissertation (2005)

Detailed reference viewed: 31 (13 ULg)
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Peer Reviewed
See detailModélisation, Simulation et Optimisation d'un Atelier de Construction Navale
Bair, Frédéric ULg; Langer, Yves; Rigo, Philippe ULg

in 6ème Conférence Francophone de MOdélisation et SIMulation - MOSIM, Maroc (2006)

This study is about the simulation of a shipbuilding workshop, and its optimization in order to improve its productivity. The objective is to model precisely a complex workshop and to evaluate ... [more ▼]

This study is about the simulation of a shipbuilding workshop, and its optimization in order to improve its productivity. The objective is to model precisely a complex workshop and to evaluate possibilities to automate the optimization. The virtual model developed will be coupled with a genetic algorithm. [less ▲]

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Peer Reviewed
See detailModélisations récentes du rôle du temps et de l'interférence en mémoire de travail: Implications cliniques
Baumans, Christine ULg; Adam, Stéphane ULg; Seron, Xavier

in Revue de Neuropsychologie, Neurosciences Cognitives et Cliniques (2012), 4(3), 186-195

During the last thirty years, Baddeley and Hitch's [4] multi-component model has been widely used as a theoretical reference point in the field of working memory. Nevertheless, recent empirical data are ... [more ▼]

During the last thirty years, Baddeley and Hitch's [4] multi-component model has been widely used as a theoretical reference point in the field of working memory. Nevertheless, recent empirical data are currently supporting new theoretical frameworks which support a more functional view of working memory. In this paper, we propose a review of these theoretical advances and their implications for clinical neuropsychology. Indeed, if the examination of normal and pathological working memory functioning plays an important role in neuropsychology, the diagnostic approach nevertheless relies on the use of a small number of paradigms which moreover could be questioned in the light of these recent models. Current literature supports the use of simplier paradigms which thoroughly control for time parameters. The aim is to improve the assessment of maintenance and processing mechanisms respectively, and their links in order to better understand what causes forgetting in working memory. This way, clinicians should be more able to define the locus of working memory deficits in several pathologies, and thus to improve the relevance of their revalidation methods. [less ▲]

Detailed reference viewed: 146 (9 ULg)
See detailModéliser en Archéologie. Le pôle Archéomatique du centre Européen d'Archéométrie de l'Université de Liège
Van Ruymbeke, Muriel ULg

Conference given outside the academic context (2009)

Detailed reference viewed: 17 (4 ULg)
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Peer Reviewed
See detailModéliser l'acquisition par les médecins de compétences en communication
Libert, Y.; Antoine, C.; Merckaert, I. et al

in Oncologie (2008), 2

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See detailModéliser l’ionosphère pour les utilisateurs Galileo simple fréquence
Bidaine, Benoît ULg

Learning material (2009)

Detailed reference viewed: 62 (7 ULg)
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See detailModéliser l’ionosphère pour les utilisateurs Galileo simple fréquence
Bidaine, Benoît ULg

Learning material (2009)

Detailed reference viewed: 45 (16 ULg)
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See detailModéliser les défaillances des PME
Crutzen, Nathalie ULg

Article for general public (2009)

Detailed reference viewed: 88 (28 ULg)
See detailThe Modelization of Domestic Service. Proceedings of the Servant Project. Volume 5
Pasleau, Suzanne ULg; Schopp, Isabellle; Sarti, Raphaella

Book published by Les Editions de l'Université de Liège (2005)

Detailed reference viewed: 21 (0 ULg)
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See detailModelization of Kirchhoff scattering by a sound ray algorithm
Embrechts, Jean-Jacques ULg

in Proceedings of the 16th International Congress on Acoustics (ICA) and 135th meeting of the Acoustical Soc. of America (ASA) - Volume 4 (1998)

Detailed reference viewed: 26 (7 ULg)