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See detailMotiver pour éduquer, un éclairage qualitatif
Cloes, Marc ULg; Ledent, Maryse ULg; Piéron, Maurice ULg

in Carlier, Ghislain (Ed.) Si l’on parlait du plaisir d’enseigner l’éducation physique (2004)

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See detailSegregation of the bulk blend fertilizers
Miserque, Olivier; Pirard, Eric ULg

in Chemometrics and Intelligent Laboratory Systems (2004), 74(1), 215-224

Bulk blend fertilizers are a mixture of different kinds of fertilizers in order to obtain a predicted N-P-K chemical composition. Although this production method has some advantages, segregation appears ... [more ▼]

Bulk blend fertilizers are a mixture of different kinds of fertilizers in order to obtain a predicted N-P-K chemical composition. Although this production method has some advantages, segregation appears at different stages, from the production to the final spreading on the field. An experiment has been implemented to predict and quantify the influence of some physical properties on the occurrence of segregation. The principle was to blend two fertilizers having identical physical properties except for one, such as size, shape or density and to measure the segregation of the blend following various operations, such as filling or emptying a container. Results show that the spread of the fragment size distribution has a big influence on the segregation of the generated heap. In order to reduce this phenomenon, the granulometric spread index (GSI) [(d(84)-d(16))/2d(50)] must be smaller than 10. Other properties don't seem to have an influence. The granulometric segregation can lead to a chemical heterogeneity. The absolute sum of the difference between d(16) and d(84) must be limited around 0.5 mm. Above this value, the chemical segregation begins to be excessive. It seems also that if there is a limited difference in size for the components, the chemical segregation is amplified if the density of the fertilizer with the biggest particles is lower. It is not the case for the difference in shape. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailA generic approach for image classification based on decision tree ensembles and local sub-windows
Marée, Raphaël ULg; Geurts, Pierre ULg; Piater, Justus ULg et al

in Proceedings of the 6th Asian Conference on Computer Vision (2004)

A novel and generic approach for image classification is presented. The method operates directly on pixel values and does not require feature extraction. It combines a simple local sub-window extraction ... [more ▼]

A novel and generic approach for image classification is presented. The method operates directly on pixel values and does not require feature extraction. It combines a simple local sub-window extraction technique with induction of ensembles of extremely randomized decision trees. We report results on four well known and publicly available datasets corresponding to representative applications of image classification problems: handwritten digits (MNIST), faces (ORL), 3D objects (COIL-100), and textures (OUTEX). A comparison with studies from the computer vision literature shows that our method is competitive with the state of the art, an interesting result considering its generality and conceptual simplicity. Further experiments are carried out on the COIL-100 dataset to evaluate the robustness of the learned models to rotation, scaling, or occlusion of test images. These preliminary results are very encouraging [less ▲]

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See detailMineral mapping in salt lakes from Sud Lipez (Bolivia) using Aster images
Caceres, Fernando; Ali-Ammar, Hamid; Pirard, Eric ULg

in Geological Remote Sensing Group Newsletter (2004), (38), 15-19

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See detailImage Analysis of Iron Oxides under the Optical Microscope.
Pirard, Eric ULg; Lebichot, Sophie

in Tassinari, L. M.; Pecchio, M.; Andrade, F. R. (Eds.) et al Applied Mineralogy: Developments in Science and Technology (2004)

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See detailDirect estimation of sieve size distributions from 2-D image analysis of sand particles
Pirard, Eric ULg; Vergara, Nicolas; Chapeau, Vincent

in Proceedings PARTEC 2004 (2004)

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See detailTélédétection et télégestion des informations géologiques : de nouvelles technologies au service du développement.
Pirard, Eric ULg; Caceres, Fernando

in Bulletin des Séances de l’Académie Royale des Sciences d’Outre-Mer = Mededelingen der Zittingen van de Koninklijke Academie voor Overzeese Wetenschappen (2004), 50(3), 321-348

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See detailContribution to the study of the relations between fish of the family of Carapidae and their holothurian hosts
Parmentier, Eric ULg

in SPC Bêche de mer, Information Bulletin (2004), 19

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See detailParasites and biotic diseases in field and cultivated sea cucumbers
Eeckhaut, Igor; Parmentier, Eric ULg; Becker, P. et al

in Lovatelli, A.; Conand, C.; Purcell, S. (Eds.) et al Advances in sea cucumber aquaculture and management (2004)

Amongst echinoderms, the Holothuroidea represents the class that is the most infested by parasites. Parasites of holothuroids are Bacteria, Protozoa and Metazoa. There are about 150 species of metazoans ... [more ▼]

Amongst echinoderms, the Holothuroidea represents the class that is the most infested by parasites. Parasites of holothuroids are Bacteria, Protozoa and Metazoa. There are about 150 species of metazoans which parasite holothuroids. Most of them are turbellarians, gastropods, copepods, crabs or fishes. The main body compartments suffering of the infestations are the digestive system and the coelom. The diseases induced by metazoan parasites are mostly structural: they create galls at the surface of the epidermis, pierce the respiratory tree or dig into the body wall down to the coelom. Most metazoans that live in the digestive system do not induce obvious diseases and their relationship with their hosts is probably close to commensalism. Most Protozoa that parasite holothuroids are sporozoans. They occur mainly in the coelom and/or the haemal system, one species having been reported infesting the gonads. Even in heavily infested hosts, the signs of disease induced by sporozoans are low: at most, host haemal lacuna is occluded by trophozoites or cysts are formed into the coelomic epithelium. The most pathogen agents reported from cultured sea cucumbers are Bacteria. Cultivated holothuroids may suffer from a bacterial disease, called skin ulceration disease, that affects their body wall. In particular, juvenile Holothuria scabra reared in the Aqua-Lab hatchery of Toliara, Madagascar, suffered from such a disease that caused death within three days. The first sign of the infection is a white spot that appears on the integument of individuals, close to the cloacal aperture. The spot extends quickly onto the whole integument leading to the death of individuals. The lesions consist in a zone where the epidermis is totally destroyed and where collagen fibres and ossicles are exposed to the external medium. This zone is surrounded by a border line where degrading epidermis is mixed with connective tissue. Lesions include three bacterial morphotypes: rod-shaped bacteria, rough ovoid bacteria, and smooth ovoid bacteria. Three species of bacteria have also been put in evidence in the white spot lesions thanks to biomolecular analyses (DGGE and sequencing): Vibrio sp., Bacteroides sp., and an a-Proteobacterium. [less ▲]

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See detailInternal energy build-up in matrix-assisted laser desorption/ionization
Gabelica, Valérie ULg; Schulz, Eric; Karas, Michael

in Journal of Mass Spectrometry [=JMS] (2004), 39(6), 579-593

This paper reports detailed studies on the internal energy of ions formed in matrix-assisted laser desorption/ionization (MALDI) using delayed extraction MALDI-time-of-flight (TOF) and atmospheric ... [more ▼]

This paper reports detailed studies on the internal energy of ions formed in matrix-assisted laser desorption/ionization (MALDI) using delayed extraction MALDI-time-of-flight (TOF) and atmospheric pressure (AP) MALDI mass spectrometric (MS) methods. We use benzylpyridinium cations as internal energy probes. Our study reveals three distinct contributions to internal energy build-up in vacuum-MALDI (classical MALDI-TOF), each having different effects on ion fragmentation. Some fragments are formed before ion extraction (i.e. no more than 100 ns after the laser impact), and they are therefore well resolved and recorded as sharp signals in the MALDI-TOFMS scan. This prompt fragmentation can have two origins: (i) in-plume thermal activation, presumably always present, and (ii) in-plume chemical activation, in the course of reactions with hydrogen radicals. In addition to early internal energy build-up associated with these well-resolved promptly formed fragments, a broad peak slightly offset to higher masses could be detected corresponding to fragments formed after the extraction has started. This second signal corresponds to a third source of internal energy in MALDI ions, (iii) the extraction-induced collisional activation of the ions with the neutral components of the plume. These three contributions are difficult to quantify in vacuum-MALDI, because of the combined influence of several parameters (nature of the matrix, spot-to-spot variability, total laser exposure, delay time, acceleration voltage) on extraction-induced fragmentation. AP-MALDI, on the other hand, has two advantages for comparative studies of analyte fragmentation. First, extraction-induced fragmentation is absent, and only the contributions of early plume activation remain. Second, the reproducibility is far better than in vacuum-MALDI. AP-MALDI is therefore expected to shed new light on the early steps of the MALDI process. Copyright (C) 2004 John Wiley Sons, Ltd. [less ▲]

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See detailA Psammosteid Heterostracan (Vertebrata: Pteraspidomorphi) from the Emsian (Lower Devonian) of the Grand Duchy of Luxembourg
Delsate, D.; Blieck, A.; Steemans, Philippe ULg

in Geologica Belgica (2004), 7(1-2), 21-26

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See detailMarket dynamics driven by the decision-making of both power producers and transmission owners
Minoia, Anna; Ernst, Damien ULg; Ilic, Marija

in Proceedings of the IEEE Power Engineering Society General Meeting 2004 (2004)

In this paper we consider an electricity market in which not only the power producers but also the transmission owners can submit a bid. The market is cleared at each stage by minimizing the sum of the ... [more ▼]

In this paper we consider an electricity market in which not only the power producers but also the transmission owners can submit a bid. The market is cleared at each stage by minimizing the sum of the production prices and the transmission prices. A model of the strategic behavior is formulated for the different agents of the system. This strategic behavior modelling leads to a market dynamics that can be used to determine the different payoffs of the agents over a temporal horizon. Simulations are carried out for several configurations of this two node power system. The influence of the transfer capacity and the market structure on the payoffs of the different agents is discussed. [less ▲]

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See detailNash equilibria and reinforcement learning for active decision maker modelling in power markets
Krause, Thilo; Andersson, Goran; Ernst, Damien ULg et al

in Proceedings of the 6th IAEE European Conference: Modelling in Energy Economics and Policy (2004)

In this paper, we study the behavior of power suppliers who submit their bids to the market place in order to maximize their payoffs. The market clearing mechanism is based on the locational marginal ... [more ▼]

In this paper, we study the behavior of power suppliers who submit their bids to the market place in order to maximize their payoffs. The market clearing mechanism is based on the locational marginal price. To study the interaction of the power suppliers, we rely on two different approaches and compare the results obtained. One approach consists of computing the Nash equilibria of the market, and the other models each player’s behavior by using reinforcement learning algorithms. Simulations are carried out on a five node power system. [less ▲]

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See detailLe WOCCQ, un outil de diagnostic des risques psychosociaux liés au travail. Création de normes et développement d'une base de données
Hansez, Isabelle ULg; Mahy, Aude; Grisard, Anne et al

in Médecine du Travail & Ergonomie= Arbeidsgezondheidszorg & Ergonomie (2004), 41(2), 79-84

Le taux d’emploi des travailleurs âgés de plus de 55 ans en Belgique est un des plus faibles d’Europe. Notre pays est loin d’atteindre les objectifs de taux d’emploi inscrits dans la Stratégie Européenne ... [more ▼]

Le taux d’emploi des travailleurs âgés de plus de 55 ans en Belgique est un des plus faibles d’Europe. Notre pays est loin d’atteindre les objectifs de taux d’emploi inscrits dans la Stratégie Européenne de l’Emploi. Ce constat doit donc inciter les autorités publiques, les entreprises et les travailleurs à réagir. Si les premières ont commencé à mettre en place des mesures structurelles pour remédier au problème, les entreprises et les travailleurs ne sont pas toujours conscients de la marge de manœuvre dont ils disposent pour relever le défi. Les stéréotypes des unes et une certaine culture du « droit à la retraite » des autres sont des obstacles de première ligne. C’est pourquoi il est primordial d’engager des sensibilisations à leur égard. Cet article présente les résultats d’une recherche menée auprès de travailleurs belges pour évaluer les motifs de départ, et la place des conditions de travail et du stress dans l’explication des retraits prématurés. Les résultats fournissent un matériel solide pour orienter non seulement la sensibilisation, mais aussi les actions à mettre en place au sein des entreprises pour encourager le maintien dans l’emploi des plus âgés. On notera par exemple que la prévention doit débuter avec les travailleurs dès l’âge de 46 ans, que la lutte contre le stress lié aux conditions de travail est nécessaire mais non suffisante pour prévenir les retraits prématurés, et qu’il faut surtout se concentrer sur une meilleure gestion des changements organisationnels et la valorisation du personnel pour endiguer les départs anticipés. [less ▲]

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See detailType trait (co)variance components for five dairy breeds
Wiggans, G. R.; Gengler, Nicolas ULg; Wright, J. R.

in Journal of Dairy Science (2004), 87(7), 2324-2330

(Co)variance components were estimated for final score and 14 or 15 linear type traits for the Ayrshire, Brown Swiss, Guernsey, Jersey, and Milking Shorthorn breeds. Appraisals from 1995 or later were ... [more ▼]

(Co)variance components were estimated for final score and 14 or 15 linear type traits for the Ayrshire, Brown Swiss, Guernsey, Jersey, and Milking Shorthorn breeds. Appraisals from 1995 or later were used. New estimates were calculated to accommodate changes in scoring of traits and because of a change from multiplicative to additive adjustment for age and lactation stage. The adjustment method was changed for better support of the adjustment for heterogeneous variance within iteration, which was implemented in 2002. The largest changes in heritability were an increase of 0.10 for rump angle for Milking Shorthorns and a decrease of 0.11 for udder depth for Jerseys. The new estimates of (co)variance components should provide improved accuracy of type evaluations, particularly for traits that have had variance changes over time. [less ▲]

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See detailPrediction of daily milk, fat, and protein production by a random regression test-day model
Mayeres, P.; Stoll, J.; Bormann, J. et al

in Journal of Dairy Science (2004), 87(6), 1925-1933

Test-day genetic evaluation models have many advantages compared with those based on 305-d lactations; however, the possible use of test-day model (TDM) results for herd management purposes has not been ... [more ▼]

Test-day genetic evaluation models have many advantages compared with those based on 305-d lactations; however, the possible use of test-day model (TDM) results for herd management purposes has not been emphasized. The aim of this paper was to study the ability of a TDM to predict production for the next test day and for the entire lactation. Predictions of future production and detection of outliers are important factors for herd management (e. g., detection of health and management problems and compliance with quota). Because it is not possible to predict the herd-test-day (HTD) effect per se, the fixed HTD effect was split into 3 new effects: a fixed herd-test month-period effect, a fixed herd-year effect, and a random HTD effect. These new effects allow the prediction of future production for improvement of herd management. Predicted test-day yields were compared with observed yields, and the mean prediction error computed across herds was found to be close to zero. Predictions of performance records at the herd level were even more precise. Discarding herds enrolled in milk recording for <1 yr and animals with very few tests in the evaluation file improved correlations between predicted and observed yields at the next test day (correlation of 0.864 for milk in first-lactation cows as compared with a correlation of 0.821 with no records eliminated). Correlations with the observed 305-d production ranged from 0.575 to 1 for predictions based on 0 to 10 test-day records, respectively. Similar results were found for second and third lactation records for milk and milk components. These findings demonstrate the predictive ability of a TDM. [less ▲]

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See detailRéseaux de surveillance des masses d’eau souterraine en Région Wallonne
Rentier, Céline; Delloye, Francis; Dassargues, Alain ULg

in Tribune de l'Eau (La) (2004), (631-632), 11-21

La mise en œuvre de la directive européenne cadre de l’eau nécessite l’élaboration, par masse d’eau souterraine, d’un réseau de mesure et de surveillance aussi représentatif que possible de l’état des ... [more ▼]

La mise en œuvre de la directive européenne cadre de l’eau nécessite l’élaboration, par masse d’eau souterraine, d’un réseau de mesure et de surveillance aussi représentatif que possible de l’état des eaux souterraines. En Région Wallonne, cinq masses d’eau de caractéristiques différentes d’un point de vue géologique, hydrogéologique et d’occupation du sol ont fait l’objet d’une étude en vue d’établir une stratégie de sélection des sites de mesures. La sélection des stations de mesure composant chaque réseau a été réalisé en tenant compte de divers critères tels que la géologie, l’hydrogéologie et l’hydrochimie de la masse d’eau, les caractéristiques des points d’eau existants, mais aussi la densité et la répartition spatiale des ouvrages sélectionnés. Le système d’évaluation de la qualité des eaux souterraines SEQESO adopté en Région Wallonne a été appliqué à chacun de ces réseaux afin d’apprécier l’état chimique de ces masses d’eaux conformément à la directive-cadre. The implementation of the European water framework directive requires the construction of monitoring networks being as far as possible representative of the global water quality in each groundwater body. In Walloon Region, five groundwater bodies with different contrasted geological conditions, hydrogeological conditions and soil occupancy, were studied in order to establish an approach for choosing an adequate network of monitoring points. This selection was realized by considering different criterions as the groundwater geology, hydrogeology and hydrochemistry, the feature of existing waterpoints, but also the density and the spatial distribution of the selected points in order to obtain a statistically representative network. The quality assessment system for groundwater (SEQESO) adopted by the Walloon Region has been applied to the five monitoring networks in order to fully appreciate the chemical status of the groundwater bodies in accordance with the European directive. [less ▲]

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See detailAggregated indicators from an optimized groundwater monitoring network: example in Walloon region of Belgium for implementation of the European Water Directive
Rentier, Céline; Delloye, Francis; Brouyère, Serge ULg et al

in Proc. of Integrated methods for assessing water quality, COST629 Workshop (2004)

Following prescriptions of the recent European Water Framework Directive, a groundwater quality evaluation system must be adopted for checking the groundwater status with respect to different contaminants ... [more ▼]

Following prescriptions of the recent European Water Framework Directive, a groundwater quality evaluation system must be adopted for checking the groundwater status with respect to different contaminants. A screening evaluation system (based on a system developed by the French Water Agencies) has been adapted to the specific conditions in the Walloon Region of Belgium. Groundwater quality data are aggregated into indicators with respect to different water uses such as drinking water standards, thresholds values for preserving dependent surface ecosystems, or the groundwater ‘natural or patrimonial state’. A global groundwater quality indicator can also be calculated. Different aggregation techniques are discussed with their respective influence on the final indicator. In relation to this evaluation, the monitoring network must be adapted for being (as far as possible) representative of the global quality of water in each groundwater body. Existing knowledge and understanding of the actual hydrogeological conditions were used in priority for choosing an adequate network of monitoring points. At the same time, the spatial density of points was checked in order to obtain a statistically representative network. Applications were performed in five different GWBodies belonging to the hydrographic district of the Meuse River in the Walloon Region and with different contrasted geological conditions: Cretaceous chalks, Carboniferous limestones and Pleistocene gravels of the alluvial plain of the River Meuse. These examples provide a good opportunity for further discussion and work about the main related issues: optimzation procedures, aggregation methods and estimation of the reliability of indicators. [less ▲]

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