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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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See detailLa pédagogie universitaire en mouvement : une stratégie en 7 clés méthodologiques et enrichissement continu pour une mise en action de compétences et un impact pratique immédiat
Poumay, Marianne ULg

in (Re)trouver le plaisir d'enseigner et d'apprendre. Construire savoirs et compétences. (2004)

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See detailCatalogue des papyrus iatromagiques grecs
de Haro Sanchez, Magali ULg

in Papyrologica Lupiensia (2004), 13

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See detailBois de feu et déboisement au Sahel: mise au point
Ozer, Pierre ULg

in Science et changements planétaires / Sécheresse (2004), 15(3), 243-251

A major environmental issue of the XXIst century, deforestation due to firewood consummation is an increasing problem within the Sahel of West Africa. This article underlines the difficulties to obtain ... [more ▼]

A major environmental issue of the XXIst century, deforestation due to firewood consummation is an increasing problem within the Sahel of West Africa. This article underlines the difficulties to obtain reliable statistics to correctly monitor deforestation. Field data on firewood consumption are dramatically lacking and inventories of forest cover are very poor. In this context, scientists and policymakers often use the data published by FAO to understand the deforestation topic. Unfortunately, we clearly demonstrate that those data are also inaccurate and not coherent. The analysis of several official documents shows that no institution is currently able to produce any reliable data on firewood and its impact on the environment. [less ▲]

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See detailAnalyse de la campagne agricole 2003 en terme de stress hydrique
De Longueville, Florence ULg; Horion, Stéphanie ULg; Tychon, Bernard ULg et al

in Bulletin de la Société Géographique de Liège (2004), 44

This article presents the evaluation of the crop water stress in 2003 using the Belgian Crop Growth Monitoring System (B-CGMS). The indicator used is the Relative Soil Moisture Index (RSMI), and is based ... [more ▼]

This article presents the evaluation of the crop water stress in 2003 using the Belgian Crop Growth Monitoring System (B-CGMS). The indicator used is the Relative Soil Moisture Index (RSMI), and is based on a calculation integrating soil moisture data. This index shows the differences between needed and effectively available soil water for different crop types. It is one of the outputs of the B-CGMS agrometeorological model. Based on a fixed threshold, days affected by water stress have been identified and computed for specific periods during which lack of soil water is likely to have dramatic impacts on crop production. The cumulative number of days affected by water stress indicator has then been integrated into a GIS to spatially represent the situation of winter wheat and maize during the 2003 crop season. Results suggest that only maize was affected by the water stress in northern and southern Belgium. In the latter area, the lack of water at key periods provoked a yield reduction ranging between 2 and 50%. [less ▲]

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See detailUtilisation de la visibilité horizontale pour l’estimation de la qualité de l’air à Niamey, Niger
Ozer, Pierre ULg

in Bulletin de la Société Géographique de Liège (2004), 44

It is now irrefutable that air pollution caused by large amounts of Total Suspended Particulates (TSP) has numerous undesired consequences on human health. Air quality deterioration in the US and in ... [more ▼]

It is now irrefutable that air pollution caused by large amounts of Total Suspended Particulates (TSP) has numerous undesired consequences on human health. Air quality deterioration in the US and in Europe caused by high concentration of African dust is seen as a major health threat although most of these countries are very distant from the Sahara. Surprisingly, no estimates of TSP levels near the Saharan dust source are available. Based on horizontal visibility measurements reduced by dust in the air, TSP levels are estimated at Niamey-Aéroport (Niger) by using different relations found in the literature. It appears that excessive TSP concentration levels are very important in magnitude and frequency. These very high TSP levels represent a tremendous public health threat that should be absolutely taken into consideration by national and international decision makers. [less ▲]

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See detailMassive binaries and colliding winds
Rauw, Grégor ULg

in EAS Publications Series (2004)

In this contribution, I review recent results from observational investigations of early-type binaries of spectral types O and Wolf-Rayet. These studies aim at an accurate determination of fundamental ... [more ▼]

In this contribution, I review recent results from observational investigations of early-type binaries of spectral types O and Wolf-Rayet. These studies aim at an accurate determination of fundamental parameters such as masses and radii of the most massive stars. In addition, multi-wavelength analyses of wind collisions in massive binaries provide constraints on the properties of stellar winds of massive stars and shock physics of cosmic plasmas. [less ▲]

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See detailRecommandations de l'ESH-ESC 2003 pour la prise en charge de l'hypertension artérielle en médecine générale
Persu, Alexandre; Krzesinski, Jean-Marie ULg; Van de Borne, Philippe

in Revue Médicale de Liège (2004), 59(9), 489-496

Guidelines for the management of arterial hypertension are regularly updated. This article summarizes the last international guidelines in this field published last year. The decision to initiate an ... [more ▼]

Guidelines for the management of arterial hypertension are regularly updated. This article summarizes the last international guidelines in this field published last year. The decision to initiate an antihypertensive treatment will not only depend on blood pressure [less ▲]

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See detailMR2048151, Sergeev, Y. A. and Swailes, D. C. and Petrie, C. J. S., Stability of uniform fluidization revisited; Physica A
Rochus, Pierre ULg

in Mathematical Reviews [=MR] (2004), 335(1-2), 9--34

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See detailDevelopment of RT-PCR assays using fluorogenic 3 minor groove binder DNA probes for detection of fruit tree viruses.
Marbot, Sophie; Kummert, Jean; Vendrame, Marina et al

in Acta Horticulturae (2004), (657), 547-551

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See detailEffect Of Pig Bodyweight On Ileal Amino Acid Endogenous Losses After Ingestion Of A Protein-Free Diet Enriched In Pea Inner Fibre Isolates
Leterme, Pascal; Thewis, André ULg

in Reproduction Nutrition Development (2004), 44(5), 407-417

The present study was conducted to evaluate whether bodyweight and the micronisation of dietary fibre affect the endogenous nitrogen and amino acid losses (ENL and EAAL) in pigs. The effect of the ... [more ▼]

The present study was conducted to evaluate whether bodyweight and the micronisation of dietary fibre affect the endogenous nitrogen and amino acid losses (ENL and EAAL) in pigs. The effect of the micronising process was tested by providing pigs with 90 g DM·kg–1 BW0.75 of a N-free diet supplemented with isolated pea inner fibres, presented in native or micronised form and with a water-holding capacity of 12 and 4 g water·g–1 DM, respectively. ENL and EAAL were measured on pigs weighing 24, 62 and 105 kg. In all cases, daily ENL increased linearly (P < 0.05) with BW, for the majority of the AA and total N. As BW increased, daily ENL, total EAAL and the majority of EAAL increased linearly independently of micronisation (P < 0.05). When expressed per kg DMI, total EAAL and the majority of each EAA decreased curvilinearly and reached nadir at around 100 kg BW. For ENL expressed per kg DMI, micronisation resulted in a curvilinear decrease with increasing BW, as compared to a linear decrease for pigs fed the native pea fibre diet (non-micronised). Micronisation of pea inner fibres did not decrease ENL or EAAL daily, except for proline. When the losses were expressed as g·k–1g DMI, micronisation did not decrease ENL but decreased (P < 0.05) endogenous losses for a majority of AA as well as for total AA. The results suggest that small pigs excrete more endogenous N per kg DMI than large pigs and that pea fibre micronisation reduces EAAL but not ENL when expressed per kg DMI. [less ▲]

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See detailImprovement Of Spray Deposit Homogeneity Using A Pwm Spray Controller To Compensate Horizontal Boom Speed Variations
Lebeau, Frédéric ULg; El Bahir, L.; Destain, Marie-France ULg et al

in Computers and Electronics In Agriculture (2004), 43(2),

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension ... [more ▼]

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension but these methods have performance and price limitations. This paper describes a spray controller aiming to compensate the effect of the horizontal boom movements on the spray deposits homogeneity. The controller is based on three main components: a control law describing the relationship between nozzle speed, nozzle flow and spray deposit; a real time measurement of the boom horizontal speed variations using micro-machined capacitive accelerometers, and pulse width modulation (PWM) nozzle flow actuators. To assess the feasibility of such a controller, a single nozzle prototype was developed and tested in the laboratory, using a nigrosine solution. Spray coverage was measured using image analysis for field representative nozzle speed variations. The spray coverage uniformity using the controller showed about 51% compensation of the variations observed without it. [less ▲]

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See detailModelling The Dynamic Distribution Of Spray Deposits
Lebeau, Frédéric ULg

in Biosystems Engineering (2004), 89(3),

A mathematical model to estimate the spray distribution of phytopharmaceutical deposits under a spray boom is proposed. It focuses on the need to take account of the dynamic effects of the forward ... [more ▼]

A mathematical model to estimate the spray distribution of phytopharmaceutical deposits under a spray boom is proposed. It focuses on the need to take account of the dynamic effects of the forward movement of the boom. These are related both to the horizontal and vertical boom movement and to the influence of aerodynamic factors on the nozzle spray distribution. The distribution of the spray deposits is computed by multiplying the nozzle spray pattern by the time needed to move from one position to the next. Mathematically, this is expressed by a convolution of the trajectory function with the nozzle spray pattern function. The model is validated through a dynamic test bench to reproduce the boom movements observed in the field. The chosen method to measure the distribution of the spray deposits is a chemical dosage of the sprayed potassium chloride (KCl) solution collected in Petri dishes. A pulse-width modulation (PWM) nozzle body fitted on the test bench is used to generate a dynamic distribution of spray deposits from which the dynamic two-dimensional nozzle spray pattern is reconstructed. This dynamic nozzle spray pattern introduced in the model allows a far better estimation of the spray deposit distribution to be made than the one obtained using the static nozzle spray pattern which was computed using filtered back-projection. [less ▲]

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See detailLe bilan azoté dans les exploitations porcines wallonnes : entre contraintes environnementales et qualité différenciée.
Degre, Aurore ULg; Verheve, Didier; Debouche, Charles ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2004), 8(2), 119-124

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