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See detailModelling system WOLF
Pirotton, Michel ULg; Archambeau, Pierre ULg; Mouzelard, Thibaut et al

Software (2000)

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See detailModelling temporal stability of EPI time series using magnitude images acquired with multi-channel receiver coils.
Hutton, Chloe; Balteau, Evelyne ULg; Lutti, Antoine et al

in PLoS ONE (2012), 7(12), 52075

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See detailModelling the Arterial Wall by Finite Elements
Mosora, F.; Harmant, A.; Hallet, Claude ULg et al

in Archives Internationales de Physiologie, de Biochimie et de Biophysique (1993), 101(3, May-Jun), 185-91

The mechanical behaviour of the arterial wall was determined theoretically utilizing some parameters of blood flow measured in vivo. Continuous experimental measurements of pressure and diameter were ... [more ▼]

The mechanical behaviour of the arterial wall was determined theoretically utilizing some parameters of blood flow measured in vivo. Continuous experimental measurements of pressure and diameter were recorded in anesthetized dogs on the thoracic ascending and midabdominal aorta. The pressure was measured by using a catheter, and the diameter firstly, at the same site, by a plethysmograph with mercury gauge and secondly, by a sonomicrometer with ferroelectric ceramic transducers. The unstressed radius and thickness were measured at the end of each experiment in situ. Considering that the viscous component is not important relatively to the nonlinear component of the elasticity and utilizing several equations for Young modulus calculation (thick and thin wall circular cylindrical tube formulas and Bergel's equation) the following values were obtained for this parameter: 0.6 MPa-2 MPa in midabdominal aorta and 2 MPa-6.5 MPa in thoracic ascending aorta. The behaviour of the aorta wall was modelled considering an elastic law and using the finite element program "Lagamine" working in large deformations. The discretized equilibrium equations are non-linear and a unique axi-symmetric, iso-parametric element of 1 cm in length with 8 knots was used for this bi-dimensional problem. The theoretical estimation of radius vessel, utilizing a constant 5 MPa Young modulus and also a variable one, are in good agreement with the experimental results, showing that this finite element model can be applied to study mechanical properties of the arteries in physiological and pathological conditions. [less ▲]

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See detailModelling the behaviour of Listeria monocytogenes in cheese
Schvartzman Echenique, Maria Sol ULg

Doctoral thesis (2011)

Cheese is a complex biological system where environmental dynamics take place between pH, moisture, water activity and temperature. Bacteria growing in or on cheese behave differently depending on the ... [more ▼]

Cheese is a complex biological system where environmental dynamics take place between pH, moisture, water activity and temperature. Bacteria growing in or on cheese behave differently depending on the cheese types or in the processing step. In this work, the behaviour of Listeria monocytogenes during cheesemaking and ripening was studied given a milk contamination or surface cross-contamination scenario. When milk was contaminated, L. monocytogenes initiated growth with a different probability during cheesemaking compared to milk or laboratory media, indicating that models built from laboratory media would not accurately predict the behaviour of L. monocytogenes in farmhouse cheese. Lower limits of growth at aw values of 0.94-0.96, depending on contamination level, were identified using an Ordinary Logistic Regression model. In the range tested, the pH showed no effect on growth initiation. Furthermore, L. monocytogenes presented considerable differences in behaviour in pasteurised or raw milk during cheesemaking and ripening. In contrast with the pasteurised milk cheeses, raw milk did not support growth of L. monocytogenes during cheesemaking but during ripening, growth occurred only in raw milk cheeses. The growth observed was modelled with a Logistic Cardinal model. When the contamination was present on the surface only, Listeria was inactivated in cheeses made with pasteurised milk (with pH < 5.4) during ripening and when aw decreased considerably. The inactivation was modelled with a Log-linear response surface model with aw as the factor with higher effect. In contrast, cheese made with raw milk or with pH around neutrality supported the growth of L. monocytogenes and was modelled with the Logistic Cardinal model with pH as the most influencing environmental factor on the growth rate. In summary, the need for food models has been demonstrated and pH and aw were the most significant variables conditioning the behaviour of L. monocytogenes in the various cheese scenarios. [less ▲]

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See detailModelling the behaviour of radionuclides in the aquatic ecosystem
Smitz, Joseph ULg; Everbecq, Etienne ULg

Scientific conference (1986, September)

Radionuclides realeased by nuclear plants in surface waters are not simply transported by the water. Other complex phenomena occur : adsorbtion/desorbtion to sediments, sedimentation and accumulation on ... [more ▼]

Radionuclides realeased by nuclear plants in surface waters are not simply transported by the water. Other complex phenomena occur : adsorbtion/desorbtion to sediments, sedimentation and accumulation on river's bed, interaction with interstitial water, and eventually resuspension in the water column. The aim of this work is the description and modelling of the majors processes which govern the contamination of surface waters and sediments by radionuclides to food chain and to man. The model is applied to the river Meuse. The results shows a good aggreement with available field measurements realized during routine surveys. [less ▲]

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See detailModelling the butterfat crystallisation process
Heyen, Georges ULg; Alleman, Xavier; Kalitventzeff, Boris ULg et al

in Computers & Chemical Engineering (1999), 23(Suppl. S), 819-822

Milk fat exhibits seasonal variations in composition and properties which are undesirable for many subsequent applications. Thus techniques are sought to process dairy products in order to achieve a ... [more ▼]

Milk fat exhibits seasonal variations in composition and properties which are undesirable for many subsequent applications. Thus techniques are sought to process dairy products in order to achieve a consistent quality. A brief introduction to milk fat presents its most important particularities, especially composition, seasonal variations, solid fat content, crystalisation and polymorphism. The differential scanning calorimetry (DSC) analysis allows to estimate the solid fat content. Different methods have been developed to estimate more and more precisely the solid fat content which is certainly an important parameter in the description of the textural properties of butterfat. The industrial crystallisation process is modelled on the basis of pilot plant data. That model allows to approach the particular temperature profile in the scraped surface heat exchangers and to give a first explanation of the involved phenomena. [less ▲]

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See detailModelling the Cape Ghir Upwelling Filament
Troupin, Charles ULg

Scientific conference (2008, December 12)

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See detailModelling the cardiovascular system
Shaw, G. M.; Chase, J. G.; Starfinger, C. et al

in Critical Care and Resuscitation : Journal of the Australasian Academy of Critical Care Medicine (2007), 9(3), 264-269

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See detailModelling the Cenozoic evolution of atmospheric CO2
François, Louis ULg; Gaillardet, J.; Godderis, Y.

in Geochimica et Cosmochimica Acta (2002), 66(15A), 243-243

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See detailModelling the climate effect on Black Grouse Population Dynamic in Rhön Biopshere Reserve
Loneux, Michèle ULg; Kolb, Karl-Heinz; Lindsey, James ULg

in Plummer, Ron (Ed.) Black Grouse Endangered Species (2005, December)

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See detailModelling the Climatic Response to Solar Variability
Gérard, Jean-Claude ULg

in Royal Society of London Philosophical Transactions Series A (1990), 330

The Sun, the primary energy source driving the climate system, is known to vary in time both in total irradiance and in spectral composition in the ultraviolet. According to solar interior evolution ... [more ▼]

The Sun, the primary energy source driving the climate system, is known to vary in time both in total irradiance and in spectral composition in the ultraviolet. According to solar interior evolution models, the solar luminosity has increased steadily by 25-30% over the past 4 × 10[SUP]9[/SUP] years. Periodic variations are also suspected with characteristic timescales of 11 or 22 years, 80-90 years and possibly longer periods. The ultraviolet radiation below 300 nm also exhibits significant changes over the 27-day solar rotation period as well as the 11-year solar cycle. Variations in the solar constant are expected to produce both direct and indirect (feedback) perturbations in the global surface temperature. A hierarchy of zero- to three-dimensional models have been used to study the complex couplings involved by such effects. The response of a zonally averaged model to possible total irradiance changes associated with the Gleissberg cycle is investigated and compared with measurements of the sea-surface temperature made since 1860. Changes in the solar ultraviolet irradiance modulate the amount and distribution of atmospheric ozone, which is predicted to change by several percent in the stratosphere. These perturbations directly affect the middle atmospheric thermal structure, but may also generate indirect effects that could possibly account for some short-term geophysical signatures of solar activity. The cycle-modulated energetic particle interaction with the middle atmosphere is also a possible source of global climatic perturbations. [less ▲]

Detailed reference viewed: 69 (5 ULg)
See detailModelling the climatic response to solar variability.
Gérard, Jean-Claude ULg

in The Earth's Climate and Variability of the Sun over Recent Millennia: Geophysical, Astronomical and Archaeological Aspects (1990)

The author summarizes the available evidence for intrinsic solar variability and describes the climatic consequences of such variations as predicted by current models. He presents model calculations of ... [more ▼]

The author summarizes the available evidence for intrinsic solar variability and describes the climatic consequences of such variations as predicted by current models. He presents model calculations of the possible temperature signature of the Gleissberg solar cycle and climatic effects of ultraviolet irradiance variations and intense solar charged particle interaction with the Earth's atmosphere. [less ▲]

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See detailModelling the Climatic Response to Solar Variability: Discussion
Pecker, J*-C; Gérard, Jean-Claude ULg

in Royal Society of London Philosophical Transactions Series A (1990), 330

Detailed reference viewed: 12 (0 ULg)
See detailModelling the Coastal Ocean’s Complex Ecohydrodynamics. A case study; the Northern Bering Sea
Nihoul, Jacques ULg; Adam, Paul; Djenidi, Salim ULg et al

in Progress in Belgian Oceanographic Research (1993)

Detailed reference viewed: 6 (0 ULg)
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See detailModelling the competition between two phytoplanktonic species
Elkafazi, Abderahman; Djenidi, Salim ULg; Nihoul, Jacques ULg

in Bulletin de la Société Royale des Sciences de Liège (1996), 65

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See detailModelling the components of binaries in the Hyades: the dependence of the mixing-length parameter on stellar mass
Yıldız, M.; Yakut, K.; Bakış, H. et al

in Monthly Notices of the Royal Astronomical Society (2006), 368(4), 1941-1948

We present our findings based on a detailed analysis of the binaries of the Hyades, in which the masses of the components are well known. We fit the models of the components of a binary system to ... [more ▼]

We present our findings based on a detailed analysis of the binaries of the Hyades, in which the masses of the components are well known. We fit the models of the components of a binary system to observations so as to give the observed total V and B-V of that system and the observed slope of the main sequence in the corresponding parts. According to our findings, there is a very definite relationship between the mixing-length parameter and the stellar mass. The fitting formula for this relationship can be given as α= 9.19(M/M[SUB]solar[/SUB]- 0.74)[SUP]0.053[/SUP]- 6.65, which is valid for stellar masses greater than 0.77M[SUB]solar[/SUB]. While no strict information is gathered for the chemical composition of the cluster, as a result of degeneracy in the colour-magnitude diagram, by adopting Z= 0.033 and using models for the components of 70 Tau and θ[SUP]2[/SUP] Tau we find the hydrogen abundance to be X= 0.676 and the age to be 670 Myr. If we assume that Z= 0.024, then X= 0.718 and the age is 720 Myr. Our findings concerning the mixing-length parameter are valid for both sets of the solution. For both components of the active binary system V818 Tau, the differences between radii of the models with Z= 0.024 and the observed radii are only about 4 per cent. More generally, the effective temperatures of the models of low-mass stars in the binary systems studied are in good agreement with those determined by spectroscopic methods. [less ▲]

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See detailModelling the Congo basin ecosystems with a dynamic vegetation model
Dury, Marie ULg; Hambuckers, Alain ULg; Trolliet, Franck ULg et al

Poster (2014, April)

The scarcity of field observations in some parts of the world makes difficult a deep understanding of some ecosystems such as humid tropical forests in Central Africa. Therefore, modelling tools are ... [more ▼]

The scarcity of field observations in some parts of the world makes difficult a deep understanding of some ecosystems such as humid tropical forests in Central Africa. Therefore, modelling tools are interesting alternatives to study those regions even if the lack of data often prevents sharp calibration and validation of the model projections. Dynamic vegetation models (DVMs) are process-based models that simulate shifts in potential vegetation and its associated biogeochemical and hydrological cycles in response to climate. Initially run at the global scale, DVMs can be run at any spatial scale provided that climate and soil data are available. In the framework of the BIOSERF project (“Sustainability of tropical forest biodiversity and services under climate and human pressure”), we use and adapt the CARAIB dynamic vegetation model (Dury et al., iForest - Biogeosciences and Forestry, 4:82-99, 2011) to study the Congo basin vegetation dynamics. The field campaigns have notably allowed the refinement of the vegetation representation from plant functional types (PFTs) to individual species through the collection of parameters such as the specific leaf area or the leaf C:N ratio of common tropical tree species and the location of their present-day occurrences from literature and available database. Here, we test the model ability to reproduce the present spatial and temporal variations of carbon stocks (e.g. biomass, soil carbon) and fluxes (e.g. gross and net primary productivities (GPP and NPP), net ecosystem production (NEP)) as well as the observed distribution of the studied species over the Congo basin. In the lack of abundant and long-term measurements, we compare model results with time series of remote sensing products (e.g. vegetation leaf area index (LAI), GPP and NPP). Several sensitivity tests are presented: we assess consecutively the impacts of the level at which the vegetation is simulated (PFTs or species), the spatial resolution and the initial land cover (potential or human-induced). First, we show simulations over the whole Congo basin at a 0.5◦ spatial resolution. Then, we present high-resolution simulations (1 km) carried out over different areas of the Congo basin, notably the DRC part of the WWF Lake Tele – Lake Tumba Landscape. Studied in the BIOSERF project, this area is characterized by a forest-savannah mosaic but also by swamp and flooded forest. In addition, forward transient projections of the model driven with the outputs of about thirty global cli- mate models (GCMs) from the new Coupled Model Intercomparison Project Phase 5 (CMIP5) will permit to outline the likely response of carbon pools to changing climate over the Congo basin during the 21th century. [less ▲]

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