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See detailA MODEL FOR WHEAT YIELD PREDICTION BASED ON REAL-TIME MONITORING OF ENVIRONMENTAL FACTORS
Dumont, Benjamin ULg; Lebeau, Frédéric ULg; Vancutsem, Françoise ULg et al

Poster (2010, July)

This paper presents the results of a one year preliminary study in which a real time monitoring system was used to feed the STICS soil crop model. As indicated by the statistical criteria (RMSE and model ... [more ▼]

This paper presents the results of a one year preliminary study in which a real time monitoring system was used to feed the STICS soil crop model. As indicated by the statistical criteria (RMSE and model efficiency), the optimization of some wheat crop parameters allows the model to predict the yields with good accuracy for different soil type and different nitrogen application rates. [less ▲]

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See detailModel GW band structure of InAs and GaAs in the wurtzite phase
Zanolli, Zeila ULg; Fuchs, F.; Furthmueller, J. et al

in Physical Review. B, Condensed Matter and Materials Physics (2007), 75(24),

We report quasiparticle calculations of the newly observed wurtzite polymorph of InAs and GaAs. The calculations are performed in the GW approximation (based on a model dielectric function) using plane ... [more ▼]

We report quasiparticle calculations of the newly observed wurtzite polymorph of InAs and GaAs. The calculations are performed in the GW approximation (based on a model dielectric function) using plane waves and pseudopotentials. For comparison we also report the study of the zinc-blende phase within the same approximations. In the InAs compound the In 4d electrons play a very important role: whether they are frozen in the core or not leads either to a correct or a wrong band ordering (negative gap) within the local-density appproximation (LDA). We have calculated the GW band structure in both cases. In the first approach, we have estimated the correction to the pd repulsion calculated within the LDA and included this effect in the calculation of the GW corrections to the LDA spectrum. In the second case, we circumvent the negative gap problem by first using the screened exchange approximation and then calculating the GW corrections starting from the so obtained eigenvalues and eigenfunctions. This approach, that can be thought of as a step towards self-consistency, leads to a more realistic band structure and was also used for GaAs. For both InAs and GaAs in the wurtzite phase we predict an increase of the quasiparticle gap with respect to the zinc-blende polytype. [less ▲]

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See detailModel Identification and FE Simulations Effect of Different Yield Loci and Hardening Laws in Sheet Forming
Flores, Paulo; Duchene, Laurent ULg; Bouffioux, Chantal ULg et al

in International Journal of Plasticity (2007), 23(3), 420-449

The bi-axial experimental equipment [Flores, P., Rondia, E., Habraken, A.M., 2005a. Development of an experimental equipment for the identification of constitutive laws (Special Issue). International ... [more ▼]

The bi-axial experimental equipment [Flores, P., Rondia, E., Habraken, A.M., 2005a. Development of an experimental equipment for the identification of constitutive laws (Special Issue). International Journal of Forming Processes] developed by Flores enables to perform Bauschinger shear tests and successive or simultaneous simple shear tests and plane strain tests. Flores investigates the material behavior with the help of classical tensile tests and the ones performed in his bi-axial machine in order to identify the yield locus and the hardening model. With tests performed on one steel grade, the methods applied to identify classical yield surfaces such as [Hill, R., 1948. A theory of the yielding and plastic flow of anisotropic materials. Proceedings of the Royal Society of London A 193, 281–297; Hosford, W.F., 1979. On yield loci of anisotropic cubic metals. In: Proceedings of the 7th North American Metalworking Conf. (NMRC), SME, Dearborn, MI, pp. 191–197] ones as well as isotropic Swift type hardening, kinematic Armstrong–Frederick or Teodosiu and Hu hardening models are explained. Comparison with the Taylor–Bishop–Hill yield locus is also provided. The effect of both yield locus and hardening model choices is presented for two applications: plane strain tensile test and Single Point Incremental Forming (SPIF). [less ▲]

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See detailModel identification and FE simulations: effect of different yield loci and hardening laws in sheet forming
Flores, Paulo; Duchene, Laurent ULg; Lelotte, Thomas et al

in Smith, L. M.; Pourboghrat, F.; Yoon, J. W. (Eds.) et al On the Cutting Edge of Technology NUMISHEET 2005, Proceedings of the 6th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes (2005)

The bi-axial experimental equipment [1] developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and ... [more ▼]

The bi-axial experimental equipment [1] developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and classical tensile tests investigate the material behavior in order to identify the yield locus and the hardening models. With tests performed on two steel grades, the methods applied to identify classical yield surfaces such as Hill or Hosford ones as well as isotropic Swift type hardening or kinematic Armstrong–Frederick hardening models are explained. Comparison with the Taylor-Bishop-Hill yield locus is also provided. The effect of both yield locus and hardening model choice will be presented for two applications: Single Point Incremental Forming (SPIF) and a cup deep drawing. [less ▲]

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See detailModel intercomparison in the Mediterranean: MEDMEX simulations of the seasonal cycle
Beckers, Jean-Marie ULg; Rixen, M.; Brasseur, P. et al

in Journal of Marine Systems (2002), 33

The simulation of the seasonal cycle in the Mediterranean by several primitive equation models is presented. All models were forced with the same atmospheric data, which consists in either a monthly ... [more ▼]

The simulation of the seasonal cycle in the Mediterranean by several primitive equation models is presented. All models were forced with the same atmospheric data, which consists in either a monthly averaged wind-stress with sea surface relaxation towards monthly mean sea surface temperature and salinity fields, or by daily variable European Centre for Medium Range Weather Forecast (ECMWF) reanalysed wind-stress and heat fluxes. In both situations models used the same grid resolution. Results of the modelling show that the model behaviour is similar when the most sensitive parameter, vertical diffusion, is calibrated properly. It is shown that an unrealistic climatic drift must be expected when using monthly averaged forcing functions. When using daily forcings, drifts are modified and more variability observed, but when performing an EOF analysis of the sea surface temperature, it is shown that the basic cycle, represented similarly by the models, consists of the seasonal cycle which accounts for more than 90% of its variability. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailModel of Electrostatic Actuated Deformable Mirror using Strongly Coupled Electro-Mechanical Finite Element
Rochus, Véronique ULg; Louis, Christophe; Golinval, Jean-Claude ULg et al

in Proceeding of Design, Test, Integration and Packaging (2006)

The aim of this paper is to deal with multi-physics simulation of micro-electro-mechanical systems (MEMS) based on an advanced numerical methodology. MEMS are very small devices in which electric as well ... [more ▼]

The aim of this paper is to deal with multi-physics simulation of micro-electro-mechanical systems (MEMS) based on an advanced numerical methodology. MEMS are very small devices in which electric as well as mechanical and fluid phenomena appear and interact. Because of their microscopic scale, strong coupling effects arise between the different physical fields, and some forces, which were negligible at macroscopic scale, have to be taken into account. In order to accurately design such micro-electro-mechanical systems, it is of primary importance to be able to handle the strong coupling between the electric and the mechanical fields. In this paper, the finite element method (FEM) is used to model the strong coupled electro-mechanical interactions and to perform static and transient analyses taking into account large mesh displacements. These analyses will be used to study the behaviour of electrostatically actuated micro-mirrors. [less ▲]

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See detailModel of electrostatic actuated deformable mirror using strongly coupled electro-mechanical finite element
Rochus, Véronique ULg; Golinval, Jean-Claude ULg; Mendez, C. et al

in Analog Integrated Circuits and Signal Processing (2007), 53(2-3), 129-135

The aim of this paper is to deal with multi-physics simulation of micro-electro-mechanical systems (MEMS) based on an advanced numerical methodology. MEMS are very small devices in which electric as well ... [more ▼]

The aim of this paper is to deal with multi-physics simulation of micro-electro-mechanical systems (MEMS) based on an advanced numerical methodology. MEMS are very small devices in which electric as well as mechanical and fluid phenomena appear and interact. Because of their microscopic scale, strong coupling effects arise between the different physical fields, and some forces, which were negligible at macroscopic scale, have to be taken into account. In order to accurately design such micro-electro-mechanical systems, it is of primary importance to be able to handle the strong coupling between the electric and the mechanical fields. In this paper, the finite element method (FEM) is used to model the strong coupled electro-mechanical interactions and to perform static and transient analyses taking into account large mesh displacements. These analyses will be used to study the behaviour of electrostatically actuated micro-mirrors. [less ▲]

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See detailA model of energy deposition of energetic electrons and EUV emission in the Jovian and Saturnian atmospheres and implications
Gérard, Jean-Claude ULg; Singh, V.

in Journal of Geophysical Research (1982), 87

A model of the interaction between incident electron precipitation and H2 atmospheres is described. The local degraded primary and secondary electron energy distributions are calculated by using the ... [more ▼]

A model of the interaction between incident electron precipitation and H2 atmospheres is described. The local degraded primary and secondary electron energy distributions are calculated by using the continuous slowing down approximation. The altitude distribution of the ionization rate and various H and EUV H2 emissions are calculated for four different incident electron spectra. A total EUV H2 emission efficiency of 10.6 kR/incident erg/sq cm per sec is obtained for a pure H2 atmosphere. Comparison with the Voyager Jupiter observations indicates that an incident energy flux of about 8 ergs/sq cm per sec was present at the time of the encounter if the emission is located in an H2-dominated region. The local thermospheric heating rate was about 4 ergs/sq cm per sec for Jupiter and of the order of 0.1 erg/sq cm per sec for Saturn. A globally averaged atomic hydrogen production rate of about 1 x 10 to the 10th atoms/sq cm per sec is induced by the Jovian auroral electron precipitation, largely exceeding the solar EUV dissociation rate. [less ▲]

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See detailModel Of Forest Carbon Sequestration Incorporating Aerial Wood Radiative Budget
Longdoz, B.; Aubinet, Marc ULg; François, Louis ULg

in Agricultural and Forest Meteorology (2004), 125(1-2), 83-104

The CHANCE model, simulating CO2, energy and water fluxes in a forest ecosystem, is presented. The components of the simulated canopy are the leaves, the branches, the trunks and the soil. The first three ... [more ▼]

The CHANCE model, simulating CO2, energy and water fluxes in a forest ecosystem, is presented. The components of the simulated canopy are the leaves, the branches, the trunks and the soil. The first three are divided into sunny and shaded zones. The model has been calibrated and validated in comparison with measurements performed in the temperate beech forest of Vielsalm (Belgium). For the reproduction of half-hourly net CO2 fluxes, the quality of the CHANCE results is comparable to other models (systematic error of 14%—0.51 molm−2 s−1, R2 = 0.79). The differences between simulated and measured fluxes result essentially from noise in the data, underestimation of the stomatal conductance during very dry days and heterogeneity of the south, southeast sector (presence of conifer patches). Three sensitivity tests have been performed. The first one, neglecting the contribution of aerial wood in the radiation budget, doubles the annual carbon sequestration (Seco). This trend is strengthened in the second test where common radiative and photosynthetic properties are assigned to leaves and branches. The third test induces a 30% reduction of Seco when the calculation of canopy component temperatures using the complete energy balance is replaced by the use of air temperature. © 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailModel of Irrigation Development for Floodplain of the Tonle Sap Great Lake
someth, Paradis; Kubo, n; Ly, Sarann ULg et al

Poster (2008)

Rice is a staple crop in Cambodia. To meet the large requirement of rice consumption due to rapid increased population and to boost the economy, the rice production in this country needs to be enhanced ... [more ▼]

Rice is a staple crop in Cambodia. To meet the large requirement of rice consumption due to rapid increased population and to boost the economy, the rice production in this country needs to be enhanced. The Tonle Sap Great Lake of Cambodia has huge floodplain suitable for large amount for rice production and potential water resources for rice-based farming system. Due to large variation of water level of the lake, some areas around the lake are flooded in wet season and shortage of water in dry season. Studies to exploit the flood and the water rsources of the lake and its tributaries have not been well conducted yet. The West Baray and Batheay irrigation systems are located in the floodplain of the Tonle Sap Great Lake and the Mekong River. In this research, the irrigation systems are studied as model sites for future development of the floodplain of the Tonle Sap Great Lake. [less ▲]

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See detailA Model of Lyman ë± and H[SUB]2[/SUB] Bands Excitation by Protons Precipitation in the Jovian Atmosphere
Rego, D.; Prangé; Gérard, Jean-Claude ULg

in Bulletin of the American Astronomical Society (1992, June 01)

Not Available

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See detailModel of reticuloendothelial iron metabolism in humans: abnormal behavior in idiopathic hemochromatosis and in inflammation.
Fillet, Georges ULg; Baldelli, L.; BEGUIN, Yves ULg

in Blood (1989), 74(2), 844-51

Iron transport in the reticuloendothelial (RE) system plays a central role in iron metabolism, but its regulation has not been characterized physiologically in vivo in humans. In particular, why serum ... [more ▼]

Iron transport in the reticuloendothelial (RE) system plays a central role in iron metabolism, but its regulation has not been characterized physiologically in vivo in humans. In particular, why serum iron is elevated and RE cells are much less iron-loaded than parenchymal cells in idiopathic hemochromatosis is not known. The processing of erythrocyte iron by the RE system was studied after intravenous (IV) injection of 59Fe heat-damaged RBCs (HDRBCs) and 55Fe transferrin in normal subjects and in patients with iron deficiency, idiopathic hemochromatosis, inflammation, marrow aplasia, or hyperplastic erythropoiesis. Early release of 59Fe by the RE system was calculated from the plasma iron turnover and the 59Fe plasma reappearance curve. Late release was calculated from the ratio of 59Fe/55Fe RBC utilization in 2 weeks. The partitioning of iron between the early (release from heme catabolism) and late (release from RE stores) phases depended on the size of RE iron stores, as illustrated by the inverse relationship observed between early release and plasma ferritin (P less than .001). There was a strong correlation between early release and the rate of change of serum iron levels during the first three hours in normal subjects (r = .85, P less than .001). Inflammation produced a blockade of the early release phase, whereas in idiopathic hemochromatosis early release was considerably increased as compared with subjects with similar iron stores. Based on these results, we describe a model of RE iron metabolism in humans. We conclude that the RE system appears to determine the diurnal fluctuations in serum iron levels through variations in the immediate output of heme iron. In idiopathic hemochromatosis, a defect of the RE cell in withholding iron freed from hemoglobin could be responsible for the high serum iron levels and low RE iron stores. [less ▲]

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See detailA model of spinal cord injury: the balloon-compressive model
Martin, Didier ULg; Franzen, R.; Robe, Pierre ULg et al

Conference (1995, September 03)

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See detailA model of subclinical chronic bronchitis induced by repeted nebulisations of bacterial lipopolysaccharide
Krafft, Emilie ULg; Bolognin, M.; Tual, Charlotte ULg et al

in 20th ECVIM Meeting - Toulouse - France - 9-12 septembre 2010 (2010, September 09)

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See detailModel of the algerian currents instability
Beckers, Jean-Marie ULg; Nihoul, Jacques ULg

in Journal of Marine Systems (1992), 3(4-5), 441-451

A preliminary ''small-perturbation'' analytical study of a non-dissipative idealized model of the Algerian Current is made, with the aim of identifying major characteristic scales and investigating the ... [more ▼]

A preliminary ''small-perturbation'' analytical study of a non-dissipative idealized model of the Algerian Current is made, with the aim of identifying major characteristic scales and investigating the reality of possible classical instability mechanisms. The simple configuration is shown to be stable, from a linear perturbation point of view. The GHER 3D Primitive Equation Model is then applied to a more realistic investigation of the Algerian Current. The GHER model is non-linear, three-dimensional, with turbulent closure, mode splitting and a sigma-Coordinate formulation. The numerical simulation shows the development and mature pattern of the instability in excellent agreement with the observations. The relative importance of the existence of a coastal boundary layer, the nature of the initial perturbation, baroclinic and non-linear effects on the instability mechanism is discussed. [less ▲]

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See detailModel of the Jovian magnetic field topology constrained by the Io auroral emissions
Hess, Sébastien; Bonfond, Bertrand ULg; Grodent, Denis ULg et al

Poster (2011, October)

The determination of the internal magnetic field of Jupiter has been the object of many studies and publications. These models have been computed from the Pioneer, Voyager, and Ulysses measurements. Some ... [more ▼]

The determination of the internal magnetic field of Jupiter has been the object of many studies and publications. These models have been computed from the Pioneer, Voyager, and Ulysses measurements. Some models also use the position of the Io footprints as a constraint: the magnetic field lines mapping to the footprints must have their origins along Io’s orbit. The use of this latter constraint to determine the internal magnetic field models greatly improved the modeling of the auroral emissions, in particular the radio ones, which strongly depends on the magnetic field geometry. This constraint is, however, not sufficient for allowing a completely accurate modeling. The fact that the footprint field line should map to a longitude close to Io’s was not used, so that the azimuthal component of the magnetic field could not be precisely constrained. Moreover, a recent study showed the presence of a magnetic anomaly in the northern hemisphere, which has never been included in any spherical harmonic decomposition of the internal magnetic field. We compute a decomposition of the Jovian internal magnetic field into spherical harmonics, which allows for a more accurate mapping of the magnetic field lines crossing Io, Europa, and Ganymede orbits to the satellite footprints observed in UV. This model, named VIPAL, is mostly constrained by the Io footprint positions, including the longitudinal constraint, and normalized by the Voyager and Pioneer magnetic field measurements. We show that the surface magnetic fields predicted by our model are more consistent with the observed frequencies of the Jovian radio emissions than those predicted by previous models. [less ▲]

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See detailModel of the Jovian magnetic field topology constrained by the Io auroral emissions
Hess, S.; Bonfond, Bertrand ULg; Grodent, Denis ULg et al

Poster (2011, July 11)

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See detailModel of the Jovian magnetic field topology constrained by the Io auroral emissions
Hess, S. L. G.; Bonfond, Bertrand ULg; Zarka, P. et al

in Journal of Geophysical Research. Space Physics (2011), 116

The determination of the internal magnetic field of Jupiter has been the object of many studies and publications. These models have been computed from the Pioneer, Voyager, and Ulysses measurements. Some ... [more ▼]

The determination of the internal magnetic field of Jupiter has been the object of many studies and publications. These models have been computed from the Pioneer, Voyager, and Ulysses measurements. Some models also use the position of the Io footprints as a constraint: the magnetic field lines mapping to the footprints must have their origins along Io's orbit. The use of this latter constraint to determine the internal magnetic field models greatly improved the modeling of the auroral emissions, in particular the radio ones, which strongly depends on the magnetic field geometry. This constraint is, however, not sufficient for allowing a completely accurate modeling. The fact that the footprint field line should map to a longitude close to Io's was not used, so that the azimuthal component of the magnetic field could not be precisely constrained. Moreover, a recent study showed the presence of a magnetic anomaly in the northern hemisphere, which has never been included in any spherical harmonic decomposition of the internal magnetic field. We compute a decomposition of the Jovian internal magnetic field into spherical harmonics, which allows for a more accurate mapping of the magnetic field lines crossing Io, Europa, and Ganymede orbits to the satellite footprints observed in UV. This model, named VIPAL, is mostly constrained by the Io footprint positions, including the longitudinal constraint, and normalized by the Voyager and Pioneer magnetic field measurements. We show that the surface magnetic fields predicted by our model are more consistent with the observed frequencies of the Jovian radio emissions than those predicted by previous models. [less ▲]

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See detailA model of the Lyman-alpha line profile in the proton aurora
Gérard, Jean-Claude ULg; Hubert, Benoît ULg; Bisikalo, Dimitry V et al

in Journal of Geophysical Research (2000), 105

The Lyman-alpha auroral emission is characterized by a broad line profile whose shape depends on the energy and pitch angle distributions of the initial proton beam, whereas its total brightness reflects ... [more ▼]

The Lyman-alpha auroral emission is characterized by a broad line profile whose shape depends on the energy and pitch angle distributions of the initial proton beam, whereas its total brightness reflects the proton energy flux precipitated into the auroral upper atmosphere. Global remote sensing of the proton aurora through its ultraviolet signature makes it is increasingly important to relate the characteristics of the Lyman-alpha emission to the physical properties of the precipitated proton flux. We present a numerical model of proton and hydrogen flux transport and kinetics based on the direct simulation Monte Carlo method. In this approach, all elastic and inelastic processes are stochastically simulated as well as is the production of Lyman-alpha photons with the associated Doppler velocity component. The model also includes collisional, geomagnetic, and geometric spreading of the proton-hydrogen beam. We show that consideration of the stochastic character of the H atom velocity redistribution after collisions produces line profiles different from those obtained in the strictly forward or mean scattering angle approximations previously used in proton transport codes. In particular, the predicted fraction of photons due to backscattered particles is considerably larger when stochastic collision scattering is considered than in the strictly forward or mean scattering angle approximations. In contrast to the median wavelength, the position of the peak in the line profile shows a weak inverse dependence on the proton energy. The efficiency of the Lyman-alpha photon production per unit incident energy flux significantly drops as the mean proton energy increases. The line profile and the amount of blue-shifted (for downward viewing) emission depends in a complex way on the initial energy and pitch angle distribution of the protons. The line profiles expected for the noon cusp and midnight proton aurora are shown to be significantly different. [less ▲]

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