Publications ORBi OA
Bookmark and Share    
Full Text
Peer Reviewed
See detailPhân bố, đặc điểm và năng suất sinh sản của lợn Bản nuôi tại Hòa Bình
Vu Dinh, Ton; Phan Dang, Thang ULg

in Journal of Science and Development (2009), 7(2), 180-185

Ban swine is raised by households of ethnic minorities, especially Muong, in the remote communes of Hoa Binh province. This breed has several advantages such as good resistance to diseases, good quality ... [more ▼]

Ban swine is raised by households of ethnic minorities, especially Muong, in the remote communes of Hoa Binh province. This breed has several advantages such as good resistance to diseases, good quality of meat. This research was conducted from July 2007 to June 2008 to determine characteristics, distribution, reproductive performance of this swine breed through by the conventional method of survey such as recording body weight data and measuring the length and chest size on weekly and monthly bases. Ban swine has a black color of coat with white feet and belly. Their hairs are long and hard. They have small and erected ears, small face, long mouth, and weak back. The age at first farrowing was 13 months. The reproductive performance was low with a litter size of 5.58 for the first litter and 9.06 for the fourth (P<0.05). The average birth weight was 0.43 kg, weaning weight at 86.33 days of age was 5.05 kg. The farrowing interval was very long (241 days) with 40.46 days from weaning to re-breeding The average monthly gain was 1.49 kg for the suckling period. Feed Converson Ratio (FCR) up to weaning was very high (19 kg concentrate and 57.4 kg of forage/kg live weight). [less ▲]

Detailed reference viewed: 159 (3 ULg)
Full Text
See detailRechercher en pratique une référence bibliographique sur un sujet donné
Pasleau, Françoise ULg

Conference (2009, February 14)

Detailed reference viewed: 43 (7 ULg)
Full Text
See detailLe BCS, une méthode simple à la source de conseils variés : ration, repro et santé
Laloux, Laurent; Bastin, Catherine ULg; Gillon, Alain ULg et al

Poster (2009, February 11)

Detailed reference viewed: 19 (6 ULg)
Full Text
See detailDécideurs, dites non à la « prime à la casse ».
Courbe, Pierre; Ozer, Pierre ULg

Article for general public (2009)

Le secteur automobile mondial se porte mal. Très mal. De mémoire de constructeur, on n’avait jamais vu cela. Les baisses de ventes enregistrées en 2008 et confirmées en janvier 2009 affolent les plus ... [more ▼]

Le secteur automobile mondial se porte mal. Très mal. De mémoire de constructeur, on n’avait jamais vu cela. Les baisses de ventes enregistrées en 2008 et confirmées en janvier 2009 affolent les plus sereins d’entre eux. La tornade ne frappe toutefois pas partout avec la même intensité. […] Une fois encore, l’environnement sert d’alibi alors que l’enjeu réel est le maintien sous perfusion d’une industrie en déclin. D’une industrie qui n’a pas su ni voulu identifier les prémices de son malaise actuel. […] [less ▲]

Detailed reference viewed: 85 (9 ULg)
Full Text
Peer Reviewed
See detailEvaluation de projets d’investissement en utilisant la simulation de Monte Carlo
BELAID, Fateh; de Wolf, Daniel ULg

Conference (2009, February 10)

L’exploration et le développement d’un champ pétrolier font face à de nom- breuses incertitudes liées aux rendements et aux coûts tout au long du cycle de vie du pro jet. A titre d’exemple les ... [more ▼]

L’exploration et le développement d’un champ pétrolier font face à de nom- breuses incertitudes liées aux rendements et aux coûts tout au long du cycle de vie du pro jet. A titre d’exemple les réserves, les investissements, les coûts opératoires, la production et le prix du pétrole sont souvent incertains. En conséquence, Il difficile de prévoir les cash-flows même pour les pro jets pétroliers les plus simples. Différentes méthodes sont disponibles pour aider les décideurs à évaluer les incertitudes, et réduire le risque des opportunités d’investissement en amont pétrolier. La simulation a été reconnue comme un outil d’analyse de risque et de prise de décision en évaluation de pro jets d’investissement en amont pétrolier au début des années 60. Aujourd’hui pra- tiquement toutes les grandes compagnies pétrolières ont incorporé la simulation dans leurs études de pro jets. Dans cet article, nous essayons d’expliquer les critères d’évalua- tion et d’analyse du risque de pro jets d’investissement en amont pétrolier basés sur les cash-flows et de montrer comment la simulation de Monte Carlo peut être utile dans ce cadre. [less ▲]

Detailed reference viewed: 258 (13 ULg)
Full Text
Peer Reviewed
See detailSélection du portefeuille de projets d'exploration production en utilisant la méthode de Markowitz
BELAID, Fateh; de Wolf, Daniel ULg

Conference (2009, February 10)

Deux caractéristiques importantes de l’investissement en exploration ou production pétrolière sont les montants financiers très importants en jeu et les incertitudes élevées. Pour ces raisons, l’analyse ... [more ▼]

Deux caractéristiques importantes de l’investissement en exploration ou production pétrolière sont les montants financiers très importants en jeu et les incertitudes élevées. Pour ces raisons, l’analyse du risque devrait être mise en oeuvre dans le processus d’évaluation et de sélection des projets. En fonction de leurs ressources disponibles, les compagnies pétrolières sélectionnent un ensemble de projets sur la base de certains critères : la valeur actuelle nette, le taux de rendement interne, l’indice de profitabilité, etc . . . Cependant, ces critères se révèlent insuffisants vu, d’une part, l’absence de la notion du risque qui est un élément essentiel de l’industrie pétrolière, et d’autre part, l’omission des interactions entre les différents projets. Dans ce travail, afin de pallier aux insuffisances de l’approche traditionnelle, nous appliquons une variante de la méthode de Markowitz afin de déterminer le portefeuille optimal de projets d’exploration ou production qui assure le meilleur compromis risque minimum-rendement maximun sous les diverses contraintes auxquelles l’entreprise est confrontée. Un cas pratique d’application de cette méthode à la sélection de projets d’exploitation pétrolière en Mer du Nord est présenté. Ce cas pratique permet d’illustrer l’influence du facteur prix du brut sur le choix du portefeuille. [less ▲]

Detailed reference viewed: 252 (8 ULg)
Full Text
See detailComparaison avec les autres méthodes de mesure (au cabinet, MAPA)
Krzesinski, Jean-Marie ULg

Conference (2009, February 07)

Detailed reference viewed: 7 (1 ULg)
Full Text
See detailOptimal Design and Dimensioning of Hydrogen Transmission Distribution Pipeline Networks
Andre, Jean; BRAC, Jean; de Wolf, Daniel ULg et al

Conference (2009, February 05)

This work considers the problem of the optimal design of an hydrogen transmission network. This design problem includes the topology determi- nation and the dimensioning problem. We define a solution ... [more ▼]

This work considers the problem of the optimal design of an hydrogen transmission network. This design problem includes the topology determi- nation and the dimensioning problem. We define a solution method that simultaneously looks for the least cost topology of the network and for the optimal diameter of each pipe. These two problems were generally solved separately these last years. The application to the case of development of future hydrogen pipeline networks in France has been conducted on several urban areas. [less ▲]

Detailed reference viewed: 116 (9 ULg)
Full Text
See detailUsing OR techniques for projets selection in the petrol industy
BELAID, Fateh; de Wolf, Daniel ULg

Conference (2009, February 05)

Two important characteristics of petroleum exploration and production investment are the high nancial amounts and uncertainties. For these rea- sons, the risk analysis should be implemented in the ... [more ▼]

Two important characteristics of petroleum exploration and production investment are the high nancial amounts and uncertainties. For these rea- sons, the risk analysis should be implemented in the projects evaluation and the selection process. Depending on their available resources, petroleum companies choose a number of projects on the basis of some criteria: the net present value, internal rate of return, pro tability index However, these criteria appear to be insu cient if we consider, on the one hand, the ab- sence of risk idea which is an essential element of the petroleum industry, on the other hand the omission of the correlations and interactions between di erent projects. In this paper, in order to make up for the lacks of the traditional approach, we apply a variant of Markowitzs method to deter- mine the e cient portfolio exploration and production projects that insure the best compromise minimum risk-maximum return under the di erent constraints faced by the company. A practical application of this method about selection of petroleum exploration projects in the North Sea is pre- sented. This practical case illustrates the in uence of the crude price in the choice of the portfolio. [less ▲]

Detailed reference viewed: 47 (4 ULg)
Full Text
See detailLa traduction dans la jurisprudence communautaire : entre non-discrimination et sécurité juridique
Sibony, Anne-Lise ULg; de Sadeleer, Nicolas

Conference (2009, February 03)

Detailed reference viewed: 71 (8 ULg)
Full Text
See detailModélisation et résolution du problème de contact mécanique et son application dans un contexte multiphysique
Bussetta, Philippe ULg

Doctoral thesis (2009)

The mechanical contact is the problem of solids mechanics that presents the most difficult nonlinearity. The good resolution of the frictional contact problem is disrupted by the noniineaxity and the non ... [more ▼]

The mechanical contact is the problem of solids mechanics that presents the most difficult nonlinearity. The good resolution of the frictional contact problem is disrupted by the noniineaxity and the non differentiability of the contact's equations (stick/unstick and the initiation of sliding). Until now, no method could be used to resolve all contact problems. This work is focused on the methods of calculation of the mechanical contact in a more general way. It could be separated in two parts. The first one concerns the creation of the systems of equations and the algorithm of resolution. The methods more used are the Penalty Method and Lagrangian Augmented Method. Although these methods are simple, they are very difficult to use because the choice of the value of penalty coefficients (normal and tangential). For this reason, a new method, the "Lagrangian Augmented Adapted Method" is proposed. This new method is based on the Lagrangian Augmented Method and on the adaptation of the penalty coefficients. With it, the user does not need to choose the value of penalty coefficients. In addition, this method has the speed of the Penalty Method and the reliability of the Lagrangian Augmented Method. The second part of this work deals with the calculation of the mechanical contact under a spatial disctretization. The method more used is the "Point-Surface" Method. The contact is calculated between every point of one surface and the other surface. This method has many limits, as the representativeness and the regularity of the solution when the boundaries are deformable and irregular. Many researches are done on another method, the "Surface-Surface" Method based on the Mortar Element Method. The mechanical contact is calculated on each node of one surface in function of the two surfaces. With this method the solution is more regular and reliable. But the calculation of the mechanical contact is more difficult, so it can not be used to the three dimensional problems. An adaptation of this method has been proposed to the two and three dimensional problems. All these methods are tested on some academics and industrials multi-physical problems. [less ▲]

Detailed reference viewed: 296 (20 ULg)
Full Text
See detailAffections du système reproducteur et équitation - quand les hormones s'en mêlent
Ponthier, Jérôme ULg; Deleuze, Stefan ULg

Conference given outside the academic context (2009)

Detailed reference viewed: 40 (9 ULg)
Full Text
See detailDesign of interactive visualization of models and students data
Mazza, R; Mazzola, L; Glahn, C et al

Report (2009)

This document reports the design of the interactive visualizations of open student models that will be performed in GRAPPLE. The visualizations will be based on data stored in the domain model and student ... [more ▼]

This document reports the design of the interactive visualizations of open student models that will be performed in GRAPPLE. The visualizations will be based on data stored in the domain model and student model, and aim at supporting learners to be more engaged in the learning process, and instructors in assisting the learners. [less ▲]

Detailed reference viewed: 75 (2 ULg)
Full Text
Peer Reviewed
See detailThe Heliospheric Imagers Onboard the STEREO Mission
Eyles, Chris; Harrison, Richard; Davis, Chris et al

in Solar Physics (2009), 254

Mounted on the sides of two widely separated spacecraft, the two Heliospheric Imager (HI) instruments onboard NASA's STEREO mission view, for the first time, the space between the Sun and Earth. These ... [more ▼]

Mounted on the sides of two widely separated spacecraft, the two Heliospheric Imager (HI) instruments onboard NASA's STEREO mission view, for the first time, the space between the Sun and Earth. These instruments are wide-angle visible-light imagers that incorporate sufficient baffling to eliminate scattered light to the extent that the passage of solar coronal mass ejections (CMEs) through the heliosphere can be detected. Each HI instrument comprises two cameras, HI-1 and HI-2, which have 20° and 70° fields of view and are off-pointed from the Sun direction by 14.0° and 53.7°, respectively, with their optical axes aligned in the ecliptic plane. This arrangement provides coverage over solar elongation angles from 4.0° to 88.7° at the viewpoints of the two spacecraft, thereby allowing the observation of Earth-directed CMEs along the Sun -- Earth line to the vicinity of the Earth and beyond. Given the two separated platforms, this also presents the first opportunity to view the structure and evolution of CMEs in three dimensions. The STEREO spacecraft were launched from Cape Canaveral Air Force Base in late October 2006, and the HI instruments have been performing scientific observations since early 2007. The design, development, manufacture, and calibration of these unique instruments are reviewed in this paper. Mission operations, including the initial commissioning phase and the science operations phase, are described. Data processing and analysis procedures are briefly discussed, and ground-test results and in-orbit observations are used to demonstrate that the performance of the instruments meets the original scientific requirements. [less ▲]

Detailed reference viewed: 194 (39 ULg)
Full Text
Peer Reviewed
See detailA multi-wavelength survey of AGN in the XMM-LSS field. I. Quasar selection via the KX technique
Nakos, Theodoros; Willis, J. P.; Andreon, S. et al

in Astronomy and Astrophysics (2009), 494

Aims. We present a sample of candidate quasars selected using the KX-technique. The data cover 0.68 deg[SUP]2[/SUP] of the X-ray Multi-Mirror (XMM) Large-Scale Structure (LSS) survey area where ... [more ▼]

Aims. We present a sample of candidate quasars selected using the KX-technique. The data cover 0.68 deg[SUP]2[/SUP] of the X-ray Multi-Mirror (XMM) Large-Scale Structure (LSS) survey area where overlapping multi-wavelength imaging data permits an investigation of the physical nature of selected sources. Methods: The KX method identifies quasars on the basis of their optical (R and z') to near-infrared (K_s) photometry and point-like morphology. We combine these data with optical (u^*,g', r',i',z') and mid-infrared (3.6-24 mum) wavebands to reconstruct the spectral energy distributions (SEDs) of candidate quasars. Results: Of 93 sources selected as candidate quasars by the KX method, 25 are classified as quasars by the subsequent SED analysis. Spectroscopic observations are available for 12/25 of these sources and confirm the quasar hypothesis in each case. Even more, 90% of the SED-classified quasars show X-ray emission, a property not shared by any of the false candidates in the KX-selected sample. Applying a photometric redshift analysis to the sources without spectroscopy indicates that the 25 sources classified as quasars occupy the interval 0.7 <= z <= 2.5. The remaining 68/93 sources are classified as stars and unresolved galaxies. [less ▲]

Detailed reference viewed: 49 (19 ULg)
Full Text
Peer Reviewed
See detailAtomic oxygen distribution in the Venus mesosphere from observations of O[SUB]2[/SUB] infrared airglow by VIRTIS-Venus Express
Gérard, Jean-Claude ULg; Saglam, Adem ULg; Piccioni, Giuseppe et al

in Icarus (2009), 199

This VIRTIS instrument on board Venus Express has collected spectrally resolved images of the Venus nightside limb that show the presence of the (0,0) band of the Deltag1-->Sigmag3 infrared atmospheric ... [more ▼]

This VIRTIS instrument on board Venus Express has collected spectrally resolved images of the Venus nightside limb that show the presence of the (0,0) band of the Deltag1-->Sigmag3 infrared atmospheric system of O[SUB]2[/SUB] at 1.27 mum. The emission is produced by three-body recombination of oxygen atoms created by photodissociation of CO[SUB]2[/SUB] on the dayside. It is consistently bright so that emission limb profiles can be extracted from the images. The vertical distribution of O[SUB]2[/SUB](Deltag1) may be derived following Abel inversion of the radiance limb profiles. Assuming photochemical equilibrium, it is combined with the CO[SUB]2[/SUB] vertical distribution to determine the atomic oxygen density. The uncertainties on the O density caused by the Abel inversion reach a few percent at the peak, increasing to about 50% near 120 km. We first analyze a case when the CO[SUB]2[/SUB] density was derived from a stellar occultation observed with the SPICAV spectrometer simultaneously with an image of the O[SUB]2[/SUB] limb airglow. In other cases, an average CO[SUB]2[/SUB] profile deduced from a series of ultraviolet stellar occultations is used to derive the O profile, leading to uncertainties on the O density less than 30%. It is found that the maximum O density is generally located between 94 and 115 km with a mean value of 104 km. It ranges from less than 1×10[SUP][/SUP] to about 5×10[SUP][/SUP] cm[SUP][/SUP] with a global mean of 2.2×10[SUP][/SUP] cm[SUP][/SUP]. These values are in reasonable agreement with the VIRA midnight oxygen profile. The vertical O distribution is generally in good agreement with the oxygen profile calculated with a one-dimensional chemical-diffusive model. No statistical latitudinal dependence of the altitude of the oxygen peak is observed, but the maximum O density tends to decrease with increasing northern latitudes. The latitudinal distribution at a given time exhibits large variations in the O density profile and its vertical structure. The vertical oxygen distribution frequently shows multiple peaks possibly caused by waves or variations in the structure of turbulent transport. It is concluded that the O[SUB]2[/SUB] infrared night airglow is a powerful tool to map the distribution of atomic oxygen in the mesosphere between 90 and 115 km and improve future Venus reference atmosphere models. [less ▲]

Detailed reference viewed: 53 (3 ULg)
Full Text
Peer Reviewed
See detailOptical Vectorial Vortex Coronagraphs using Liquid Crystal Polymers: theory, manufacturing and laboratory demonstration
Mawet, D.; Serabyn, E.; Liewer, K. et al

in Optics Express (2009), 17

Detailed reference viewed: 26 (6 ULg)
Full Text
Peer Reviewed
See detailDust in the inner regions of debris disks around A stars
Akeson, R. L.; Ciardi, D. R.; Millan-Gabet, R. et al

in Astrophysical Journal (2009), 691

We present infrared interferometric observations of the inner regions of two A-star debris disks, beta Leo and zeta Lep, using the FLUOR instrument at the CHARA interferometer on both short (30 m) and ... [more ▼]

We present infrared interferometric observations of the inner regions of two A-star debris disks, beta Leo and zeta Lep, using the FLUOR instrument at the CHARA interferometer on both short (30 m) and long (> 200 m) baselines. For the target stars, the short-baseline visibilities are lower than expected for the stellar photosphere alone, while those of a check star, delta Leo, are not. We interpret this visibility offset of a few percent as a near-infrared (NIR) excess arising from dust grains which, due to the instrumental field of view, must be located within several AU of the central star. For beta Leo, the NIR excess-producing grains are spatially distinct from the dust which produces the previously known mid-infrared (MIR) excess. For zeta Lep, the NIR excess may be spatially associated with the MIR excess-producing material. We present simple geometric models which are consistent with the NIR and MIR excesses and show that for both objects, the NIR-producing material is most consistent with a thin ring of dust near the sublimation radius, with typical grain sizes smaller than the nominal radiation pressure blowout radius. Finally, we discuss possible origins of the NIR-emitting dust in the context of debris disk evolution models. [less ▲]

Detailed reference viewed: 22 (1 ULg)
Full Text
See detailGJ 436c? The contribution of transit timings
Demory, B*-O; Gillon, Michaël ULg; Waelkens, C. et al

in IAU Symposium 253: Transiting planets (2009, February 01)

From recent high-accuracy transit timings measurements, we discard the 5 M_earth planet recently proposed by Ribas et al. (2008). Thanks to a combined radial-velocity and transit timings overview we also ... [more ▼]

From recent high-accuracy transit timings measurements, we discard the 5 M_earth planet recently proposed by Ribas et al. (2008). Thanks to a combined radial-velocity and transit timings overview we also define a mass/period domain in which a secondary planet may be found in the system. We also show that timings obtained until now, although not sufficient to remove degeneracies on mass and period, can still restrict the parameter space of the potential secondary planet. [less ▲]

Detailed reference viewed: 15 (2 ULg)