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See detailModeling the influence of the Greenland ice sheet melting on the Atlantic meridional overturning circulation during the next millennia
Fichefet, Thierry; Driesschaert, Emmanuelle; Goosse, Hugues et al

Conference (2007, April 19)

A three-dimensional Earth system model of intermediate complexity including a dynamic ice sheet component has been used to investigate the long-term evolution of the Greenland ice sheet and its effects on ... [more ▼]

A three-dimensional Earth system model of intermediate complexity including a dynamic ice sheet component has been used to investigate the long-term evolution of the Greenland ice sheet and its effects on the Atlantic meridional overturning circulation (AMOC) in response to a range of stabilized anthropogenic forcings. Our results suggest that the Greenland ice sheet volume should experience a significant decrease in the future. For a radiative forcing exceeding 7.5 W m-2, the modeled ice sheet melts away within 3000 years. A number of feedbacks operate during this deglaciation, implying a strong non-linear relationship between the radiative forcing and the melting rate. In the most extreme scenario considered, the freshwater flux from Greenland into the surrounding oceans is higher than 0.1 Sv during a few centuries. This is however insufficient to induce a shutdown of the AMOC in the model. [less ▲]

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See detailModeling the instantaneous pressure-volume relationship in the left ventricle
Lucas, Alexandra ULg; Dauby, Pierre ULg; Desaive, Thomas ULg et al

in 9th Belgian Day on Biomedical Engineering, Friday November 26th 2010 in the Academy Palace, Hertogstraat 1, 1000 Brussels (2010, November 26)

Models and simulations are very useful to study interactions between anatomic structures and physical cardiac phenomena. In this work, we are interested in models of the instantaneous pressure-volume ... [more ▼]

Models and simulations are very useful to study interactions between anatomic structures and physical cardiac phenomena. In this work, we are interested in models of the instantaneous pressure-volume relationship, i.e. isochrone models. More precisely, we concentrate on the 6 models considered by Lankhaar et al. [1]. We propose a critical analysis of the work of these authors and suggest some improvement of their procedure. [1] Lankhaar J.-W. et al. Modeling the Instantaneous Pressure–Volume Relation of the Left Ventricle: A Comparison of Six Models. Annals of Biomedical Engineering, Volume 37, Number 9, 1710-1726, 2009. [less ▲]

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See detailModeling the instantaneous pressure-volume relationship in the left ventricle
Lucas, Alexandra ULg; Dauby, Pierre ULg; Kolh, Philippe ULg et al

Poster (2010, November 26)

Pressure-volume loops are a common modeling tool of the cardiovascular system. They are very useful because they characterize the global function of the cardiac pump and can also be analyzed ... [more ▼]

Pressure-volume loops are a common modeling tool of the cardiovascular system. They are very useful because they characterize the global function of the cardiac pump and can also be analyzed by considering the various phases of the cardiac cycle and marking each point of a cycle with the corresponding time. When several loops are considered, the points corresponding to the same time t in each loop can be joined to define a curve named isochrone. In this work, we are interested in models of the instantaneous pressure-volume relationship, i.e. isochrone models. More precisely, we concentrate on the 6 models considered by Lankhaar et al. [1] and we propose a critical analysis of the work of these authors and suggest some improvement of their procedure. [1] Lankhaar J.W. et al. Annals of Biomedical Engineering, Volume 37, Number 9, 1710-1726, 2009. [less ▲]

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See detailModeling the Martian ionosphere using the Total Electron Content measurement by the NEIGE/NETLANDER experiment
Morel, Laurent; Witasse, Olivier; Warnant, René ULg et al

in Proceedings of the XXVII URSI General Assembly (2002)

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See detailModeling the Martian ionosphere using the Total Electron Content measurement by the NEIGE/NETLANDER experiment
Morel, Laurent; Witasse, Olivier; Warnant, René ULg et al

Poster (2001)

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See detailModeling the mass and surface heat budgets in a coastal blue ice area of Adelie Land, Antarctica
Favier, Vincent; Agosta, Cécile ULg; Genthon, Christophe et al

in Journal of Geophysical Research. Earth Surface (2011), 116

Meteorological data recorded from 12 December 2008 to 30 June 2010 were analyzed to assess the surface energy balance (SEB) in a blue ice area of Cap Prudhomme, Adelie Land (66 degrees 41'S, 139 degrees ... [more ▼]

Meteorological data recorded from 12 December 2008 to 30 June 2010 were analyzed to assess the surface energy balance (SEB) in a blue ice area of Cap Prudhomme, Adelie Land (66 degrees 41'S, 139 degrees 55'E). The SEB was computed with a newly developed model forced by direct measurements and with a voluntarily limited number of parameters to better assess model sensitivity. Incoming short-wave radiation was corrected for the slope and orientation of the local terrain assuming direct and diffuse radiation components. Turbulent heat fluxes were assessed using the bulk aerodynamic approach. Heat conduction in the ice was computed by solving the thermal diffusion equation. Snow accumulation was modeled using ERA interim total precipitation and a one-dimensional erosion model. The surface heat budget and accumulation/erosion model accurately reproduced field observations. The occurrence of blue ice is linked with higher rates of erosion than in the surrounding snow covered areas, which may be caused by local flow divergence or snow not being redistributed from higher elevations. Melting occurs between December and February when incoming short-wave radiation is high. However, the SEB was closely linked to air temperature through the incoming long-wave radiation and the turbulent sensible heat flux. Several warm events caused by cyclones intruding into the continent led to significant warming of the ice and high melting rates. Intruding cyclones were also associated with high precipitation that led to significant accumulation. Except in blue ice areas, modeling suggests that expected higher precipitation in a warmer climate will result in more accumulation. [less ▲]

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See detailModeling the mechanical behavior of concrete in the fire situation
Gernay, Thomas ULg

Scientific conference (2012, April 26)

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See detailModeling the morphology and mechanical behavior of shape memory polyurethanes based on solid-state NMR and synchrotron SAXS/WAXD
D'Hollander, Stijn; Gommes, Cédric ULg; Mens, Raoul et al

in Journal of Materials Chemistry (2010), 20

A combination of solid-state proton Wide-line Nuclear Magnetic Resonance (NMR) relaxometry and synchrotron Small-angle (SAXS) and Wide-angle (WAXD) X-ray scattering was used to elucidate the microphase ... [more ▼]

A combination of solid-state proton Wide-line Nuclear Magnetic Resonance (NMR) relaxometry and synchrotron Small-angle (SAXS) and Wide-angle (WAXD) X-ray scattering was used to elucidate the microphase morphology of shape memory thermoplastic multi-block polyurethanes based on poly(3-caprolactone), as switching segment and polyurethane based permanent or hard segments (HS). The polyurethanes are produced from the condensation of 1,4-butanediol (BDO) with hexamethylenediisocyanate (HDI). The morphology – induced by the hard-segment crystallization – converts from dispersed randomly placed hard-segment domains into progressively more periodic, but interconnected HS nanophases with increasing HS content. Irrespective of the actual morphology, the SAXS data could be described satisfactorily by using a clipped Gaussian random field (GRF) model. The NMR data demonstrate that the HS domain fraction corresponds to the chemical feed, pointing at a complete phase separation. The material mechanical behavior during repeated deformation cycles can be explained on morphological grounds and involves a spatially heterogeneous plastic deformation of the hard domains. [less ▲]

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See detailModeling the mutation of socio-ecosystems in Central Africa
Gillet, Pauline ULg; Vermeulen, Cédric ULg

Poster (2013, February)

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See detailModeling the nitrogen cycling and plankton productivity in the Black Sea using a three-dimensional interdisciplinary model
Grégoire, Marilaure ULg; Soetaert, Karline; Nezlin, Nikolay Pavlovich et al

in Journal of Geophysical Research. Oceans (2004), 109(C5),

[1] A six-compartment ecosystem model defined by a simple nitrogen cycle is coupled with a general circulation model in the Black Sea so as to examine the seasonal variability of the ecohydrodynamics ... [more ▼]

[1] A six-compartment ecosystem model defined by a simple nitrogen cycle is coupled with a general circulation model in the Black Sea so as to examine the seasonal variability of the ecohydrodynamics. Model results show that the annual cycle of the biological productivity of the whole basin is characterized by the presence of a winter-early spring bloom. In all the regions this bloom precedes the onset of the seasonal thermocline and occurs as soon as the vertical winter mixing decreases. Phytoplankton development starts in winter in the central basin, while in coastal areas ( except in the river discharge area) it begins in early spring. In the Danube's discharge area and along the western coast, where surface waters are almost continuously enriched in nutrient by river inputs, the phytoplankton development is sustained during the whole year at the surface. The seasonal variability of the northwestern shelf circulation induced by the seasonal variations in the Danube discharge and the wind stress intensity has been found to have a major impact on the primary production repartition of the area. In the central basin the primary production in the surface layer relies essentially on nutrients being entrained in the upper layer from below. Simulated phytoplankton concentrations are compared with satellite and field data. It has been found that the model is able to reproduce the main characteristics of the space-time evolution of the Black Sea's biological productivity but underestimates the phytoplankton biomass especially in regions extremely rich in nutrients such as the Danube discharge area. [less ▲]

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See detailModeling the nitrogen fluxes in the Black Sea using a 3D coupled hydrodynamical-biogeochemical model: transport versus biogeochemical processes, exchanges across the shelf break and comparison of the shelf and deep sea ecodynamics
Grégoire, Marilaure ULg; Beckers, Jean-Marie ULg

in Biogeosciences (2004), 1(1), 33-61

A 6-compartment biogeochemical model of nitrogen cycling and plankton productivity has been coupled with a 3D general circulation model in an enclosed environment (the Black Sea) so as to quantify and ... [more ▼]

A 6-compartment biogeochemical model of nitrogen cycling and plankton productivity has been coupled with a 3D general circulation model in an enclosed environment (the Black Sea) so as to quantify and compare, on a seasonal and annual scale, the typical internal biogeochemical functioning of the shelf and of the deep sea as well as to estimate the nitrogen and water exchanges at the shelf break. Model results indicate that the annual nitrogen net export to the deep sea roughly corresponds to the annual load of nitrogen discharged by the rivers on the shelf. The model estimated vertically integrated gross annual primary production is 130 g C m(-2) yr(-1) for the whole basin, 220 g C m(-2) yr(-1) for the shelf and 40 g C m(-2) yr(-1) for the central basin. In agreement with sediment trap observations, model results indicate a rapid and efficient recycling of particulate organic matter in the sub-oxic portion of the water column (60-80 m) of the open sea. More than 95% of the PON produced in the euphotic layer is recycled in the upper 100 m of the water column, 87% in the upper 80 m and 67% in the euphotic layer. The model estimates the annual export of POC towards the anoxic layer to 4 10(10) mol yr(-1). This POC is definitely lost for the system and represents 2% of the annual primary production of the open sea. [less ▲]

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See detailModeling the oxygen K absorption in the interstellar medium : an XMM-Newton view of Sco X-1
Garcia, J; Ramirez, J M; Kallman, T R et al

in Astrophysical Journal Letters (2011), 731

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See detailMODELING THE PHANEROZOIC CARBON-CYCLE AND CLIMATE - CONSTRAINTS FROM THE SR-87-SR-86 ISOTOPIC RATIO OF SEAWATER
François, Louis ULg; WALKER, J. C. G.

in American Journal of Science (1992), 292(2), 81-135

A numerical model describing the coupled evolution of the biogeochemical cycles of carbon, sulfur, calcium, magnesium, phosphorus, and strontium has been developed to describe the long-term changes of ... [more ▼]

A numerical model describing the coupled evolution of the biogeochemical cycles of carbon, sulfur, calcium, magnesium, phosphorus, and strontium has been developed to describe the long-term changes of atmospheric carbon dioxide and climate during the Phanerozoic. The emphasis is on the effects of coupling the cycles of carbon and strontium. Various interpretations of the observed Phanerozoic history of the seawater Sr-87/Sr-86 ratio are investigated with the model. More specifically, the abilities of continental weathering, volcanism, and surface lithology in generating that signal are tested and compared. It is suggested that the observed fluctuations are mostly due to a changing weatherability over time. It is shown that such a conclusion is very important for the modelling of the carbon cycle. Indeed, it implies that the conventional belief that the evolution of atmospheric carbon dioxide and climate on a long time scale is governed by the balance between the volcanic input of CO2 and the rate of silicate weathering is not true. Rather carbon exchanges between the mantle and the exogenic system are likely to have played a kev role too. Further, the increase of the global weathering rates with increasing surface temperature and/or atmospheric CO2 pressure usually postulated in long-term carbon cycle and climate modelling is also inconsistent with the new model. Other factors appear to have modulated the weatherability of the continents through time, such as mountain building and the existence of glaciers and ice sheets. Based on these observations, a history of atmospheric carbon dioxide and climate during Phanerozoic time, consistent with the strontium isotopic data, is reconstructed with the model and is shown to be compatible with paleoclimatic indicators, such as the timing of glaciation and the estimates of Cretaceous paleotemperatures. [less ▲]

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See detailModeling the potential for Eurasian Lynx (Lynx lynx) return in lowland Western Europe
Bouyer, Yaëlle ULg; Poncin, Pascal ULg; Beudels-Jamar, Roseline et al

Poster (2011, December 06)

In the last forty years, tolerance of anthropic environment has allowed large carnivores to recolonize and expand their distribution in Western Europe. To assess the full potential and consequences of ... [more ▼]

In the last forty years, tolerance of anthropic environment has allowed large carnivores to recolonize and expand their distribution in Western Europe. To assess the full potential and consequences of this return, habitat use and landscape modeling are particularly useful tools that allow conservationists to come up with reliable prediction, and policy makers to anticipate management planning. The considerable power of dispersal and important space requirements of these species necessitate large-scale modeling, but it is essential to work in parallel at very fine scale, as carnivores’ impact on human societies is mostly felt at local level. Management of large carnivores must therefore be multi-scalar, with different decisions taken at multiple levels. With the return of the Eurasian Lynx (Lynx lynx) to lowland Western Europe, in regions of relatively high human densities, conservation- planning decisions must be knowledge based. Different approaches will be followed to analyze data at finer and larger scales. These include differential distribution and tolerance of lynx to fragmentation and anthropization, influence of landscape on lynx predation and the development of a conceptual model aiming at responding efficiently to conflicts with human populations. Results will permit the development of a lowland Western Europe habitat model, and to propose conservation measures adapted to the return of this emblematic carnivore. Results will permit the development of a lowland Western Europe habitat model, and to propose conservation measures adapted to the return of this emblematic carnivore. [less ▲]

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See detailModeling the sound transmission coupled through partition walls using a diffusion model
Billon, Alexis ULg; Foy, Cédric; Picaut, Judicaël et al

in Journal of the Acoustical Society of America (2008), 123(6), 4261-4271

In this paper, a modification of the diffusion model for room acoustics is proposed to account for sound transmission between two rooms, a source room and an adjacent room, which are coupled through a ... [more ▼]

In this paper, a modification of the diffusion model for room acoustics is proposed to account for sound transmission between two rooms, a source room and an adjacent room, which are coupled through a partition wall. A system of two diffusion equations, one for each room, together with a set of two boundary conditions, one for the partition wall and one for the other walls of a room, is obtained and numerically solved. The modified diffusion model is validated by numerical comparisons with the statistical theory for several coupled-room configurations by varying the coupling area surface, the absorption coefficient of each room, and the volume of the adjacent room. An experimental comparison is also carried out for two coupled classrooms. The modified diffusion model results agree very well with both the statistical theory and the experimental data. The diffusion model can then be used as an alternative to the statistical theory, especially when the statistical theory is not applicable, that is, when the reverberant sound field is not diffuse. Moreover, the diffusion model allows the prediction of the spatial distribution of sound energy within each coupled room, while the statistical theory gives only one sound level for each room. [less ▲]

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See detailModeling the Structural Behavior in Case of Fire
Franssen, Jean-Marc ULg

Scientific conference (1996, July 15)

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See detailModeling the uncertainty of runoff flow path on a small agricultural watershed
Ouedraogo, Mohamar ULg

Scientific conference (2013, July 01)

Recently, many munipalities have been concerned by muddy floods in Belgium after rain events. Unfortunately they lead to many consequences related to financial and emotional aspects. For many years the ... [more ▼]

Recently, many munipalities have been concerned by muddy floods in Belgium after rain events. Unfortunately they lead to many consequences related to financial and emotional aspects. For many years the government have been trying to find solutions by helping municipalities by providing them with technical support through projects like ERRUISSOL and GISER. To implement solutions, it is necessary to be able to predict runoff flow path on agricultural watersheds. This is done by applying water flow direction algorithms on digital elevation model (DEM) built from elevation data. However, digital elevation models are not free of errors, and therefore they can impact the extracted flow path position. Our aim is to present the Monte Carlo simulation that is used to model the uncertainty of runoff flow path extracted from high resolution DEM built from terrestrial laser scanner. [less ▲]

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