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See detailDistribution of temperature in steel and composite beams and joints under natural fire
Hanus, François; Franssen, Jean-Marc ULg

Conference (2011, April 29)

Parametric numerical analyses have been performed with SAFIR for the temperature distribution in steel and composite beams and joints subjected to natural fires. A simple model has been derived to ... [more ▼]

Parametric numerical analyses have been performed with SAFIR for the temperature distribution in steel and composite beams and joints subjected to natural fires. A simple model has been derived to calculate the temperature development in the upper flange of the steel section supporting a concrete slab. This model takes into account, not only the heat transfer with the surounding hot gases, but also the heat transfer 1) by conduction with the lower part of the section through the web and 2) with the supported concrete slab. [less ▲]

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See detailDistribution of temperature in steel and composite beams and joints under natural fire
Hanus, François; Franssen, Jean-Marc ULg

in Cahier Scientifique - Revue Technique Luxembourgeoise (2010), 2

The present article describes the existing methods and recommendations for the evaluation of temperature profiles in steel beams and joints covered by a concrete slab. Then, modifications and improvements ... [more ▼]

The present article describes the existing methods and recommendations for the evaluation of temperature profiles in steel beams and joints covered by a concrete slab. Then, modifications and improvements to the existing methods are proposed in order to predict more accurately temperatures at the level of the top flange of the beam by accounting for heat fluxes between the steel elements and the concrete slab. The two methods presented in this article differ by the degree of simplicity, the field of applicability and the accuracy of the predicted results. Comparisons with numerical simulations performed in the finite element program SAFIR have been described for the validation of these new methods. It is assumed in these numerical models that the contact between the steel profile and the concrete slab is perfect. The “original” Lumped Capacity Method gives globally good predictions of temperature in steel and composite beams and joints but does not integrate heat fl uxes between the steel elements and the concrete slab. This leads to an over-estimation of temperature in the steel elements during the heating phase and to an under-estimation of temperature during the cooling phase. In order to take these fluxes into consideration in the evaluation of the top flange temperature, it is suggested in the first proposed method to integrate a part of the concrete slab into the heated surface or volume considered in the Lumped Capacitance Method. The Composite Section Method correctly predicts temperature at the level of the top flange under ISO fire or during the heating phase of parametrical fire curves but a delay is observed between these analytical results and those obtained from numerical simulations performed in SAFIR software. In a second method, called Heat Exchange Method, it is proposed to calculate separately the heat fluxes between, on one side, the top flange and, on the other side, the gases of the compartment, the rest of the steel section and the concrete slab. The temperatures given by this latter method are in very good agreement with those obtained from FE models. The use of this method is really less fastidious than the use of FE models, especially for joints, but is limited to a certain type of fire curves (parametrical fire curves defined in the Annex A of the EN 1991-1-2). Finally, a bilinear temperature profi le has been proposed to interpolate the analytically-calculated temperatures at the level of the top and bottom flanges on the total height. This procedure is simple and shows a good agreement with the numerical results in 2-D beam sections and 3-D joint zones during the heating and cooling phases of parametric fire curves. [less ▲]

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See detailDistribution of Thalicea on a transect from the Gulf of Aden to the central Red Sea during the winter monsoon (March 1979)
Godeaux, Jean ULg

in Oceanologica Acta (1987), 10(2),

Ten vertical samplings were carried out at five different stations. Eight species of Salps and six species of Doliolids were collected and their distribution examined. No Pyrosoma was caught. Catch below ... [more ▼]

Ten vertical samplings were carried out at five different stations. Eight species of Salps and six species of Doliolids were collected and their distribution examined. No Pyrosoma was caught. Catch below 100 m were not very numerous. Several species of Salps and Doliolids know from the northern Red Sea and its appendages were present in the catches: Brooksia rostrata, Ritteriella amboinensis, Iasis zonaria, Thalia cicar, Salpa cylindrica, Doliolina indicum, D. muelleri, D. krohni, Doliolum nationalis and D. denticulatum. Doliolina indicum, common in the northern part of the Sea and in the Gulf of Aquaba, was the most frequently caught species of Doliolid. Pegea confoederata, a new record, was locally very abundant. The standing stock of Thaliacea was very low, except at the N'Djebel Tair and Commision Plain stations. [less ▲]

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See detailDistribution of the foraging activity of females Antarctic fur seal (Actocephalus Gazella)
Dubroca, Laurent; Guinet, Christophe; Lea, Mary-Anne et al

in Oceanographic factors and prey distribution at Kerguelen island : a two-year comparison (2000)

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See detailDistribution of the forces in a bolted connection under shear loading
Pietrapertosa, C.; Piraprez, E.; Jaspart, Jean-Pierre ULg

in Proceedings of the Fifth International Workshop on Connections (2004)

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See detailDistribution of the O[SUB]2[/SUB] infrared nightglow observed with VIRTIS on board Venus Express
Gérard, Jean-Claude ULg; Saglam, Adem ULg; Piccioni, G. et al

in Geophysical Research Letters (2008), 35

We present characteristics of the statistical horizontal distribution of the O[SUB]2[/SUB] infrared nightglow over most of the southern hemisphere observed with the VIRTIS instrument over a period ... [more ▼]

We present characteristics of the statistical horizontal distribution of the O[SUB]2[/SUB] infrared nightglow over most of the southern hemisphere observed with the VIRTIS instrument over a period spanning nearly 11 months of low solar activity. We show that the distribution is inhomogeneous with the regions of brightest emission reaching ~3 MegaRayleighs (MR) located at low latitude near and dawnward of the midnight meridian. The hemispherically averaged nadir brightness is 1.3 MR, in very good agreement with earlier ground based observations. We show that the dayside supply of O atoms is sufficient to produce the observed global O[SUB]2[/SUB] nightglow if approximately 50% of the dayside O production is carried to the nightside by the subsolar to antisolar global circulation. Limb profiles observed at northern mid-latitudes exhibit large intensity variations over short time periods. Calculations with a one-dimensional chemical diffusive model produce an airglow peak at 96 km, in agreement with the limb observations. The atomic oxygen density derived from the best fits to O[SUB]2[/SUB] airglow limb profiles reaches a maximum of 1.8-3.5 × 10[SUP]11[/SUP] cm[SUP]-3[/SUP] at 104 km. [less ▲]

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See detailDistribution of the ultraviolet nitric oxide Martian night airglow: Observations from Mars Express and comparisons with a one-dimensional model
Cox, Cédric ULg; Saglam, Adem ULg; Gérard, Jean-Claude ULg et al

in Journal of Geophysical Research (2008), 113

Limb observations with the SPICAM ultraviolet spectrometer on board the Mars Express orbiter revealed ultraviolet nightglow emission in the delta (190–240 nm) and gamma (225–270 nm) bands of nitric oxide ... [more ▼]

Limb observations with the SPICAM ultraviolet spectrometer on board the Mars Express orbiter revealed ultraviolet nightglow emission in the delta (190–240 nm) and gamma (225–270 nm) bands of nitric oxide. This emission arises from radiative recombination between O(3P) and N(4S) atoms that are produced on the day side and form excited NO molecules on the night side. In this study, we analyze the night limb observations obtained during the MEX mission. In particular, we describe the variability of the emission brightness and its peak altitude. We examine possible correlations with latitude, local time, magnetic field strength or solar activity. We show that the altitude of maximum emission varies between 55 and 92 km while the brightness is in the range 0.2 to 10.5 kR. The total vertical emission rate ranges from 8 to 237 R with an average value of 36 ± 52 R. The observed topside scale height of the emission profile varies between 3.8 and 11.0 km, with a mean value of 6 ± 1.7 km. We use a chemical-diffusive atmospheric model where the eddy coefficient, whose value in the Mars thermosphere is uncertain, is a free parameter to match the observed peak altitude of the emission. The model solves the continuity equation for O(3P), N(4S), and NO using a finite volume method on a one-dimensional grid. We find that the downward flux of N atoms at 100 km varies by two orders of magnitude, ranging from 10E7 to 10E9 atoms cm-2 s-1. [less ▲]

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See detailDistribution of trace elements in organs of six species of cetaceans from the Ligurian Sea (Mediterranean), and the relationship with stable carbon and nitrogen ratios
Capelli, R.; Das, Krishna ULg; De Pellegrini, R. et al

in Science of the Total Environment (2008), 390

Mercury (total and organic), cadmium, lead, copper, iron, manganese, selenium and zinc concentrations were measured in different organs of 6 different cetacean species stranded in an area of extraordinary ... [more ▼]

Mercury (total and organic), cadmium, lead, copper, iron, manganese, selenium and zinc concentrations were measured in different organs of 6 different cetacean species stranded in an area of extraordinary ecological interest (Cetaceans’ Sanctuary of the Mediterranean Sea) along the coast of the Ligurian Sea (North-West Mediterranean). Stable-isotopes ratios of carbon (13C/12C) and nitrogen (15N/14N) were also measured in the muscle. A significant relationship exists between 15N/14N, mercury concentration and the trophic level. The distribution of essential and non-essential trace elements was studied on several organs, and a significant relationship between selenium and mercury, with a molar ratio close to 1, was found in the cetaceans’ kidney, liver and spleen, regardless of their species. High selenium concentrations are generally associated with a low organic to total mercury ratio. While narrow ranges of concentrations were observed for essential elements in most organs, mercury and selenium concentrations are characterised by a wide range of variation. Bio-accumulation and bio-amplification processes in cetaceans can be better understood by comparing trace element concentrations with the stable-isotopes data. [less ▲]

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See detailDistribution of trypsin inhibitor activity in pea varieties.
Leterme, Pascal; Monmart, T.; Thewis, André ULg

in First European Conference of Grain Legumes, Angers (Fr), June 1-3, 1992 (1992, June)

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See detailThe Distribution of Tyrosine Hydroxylase in the Canary Brain: Demonstration of a Specific and Sexually Dimorphic Catecholaminergic Innervation of the Telencephalic Song Control Nulcei
Appeltants, D.; Ball, G. F.; Balthazart, Jacques ULg

in Cell & Tissue Research (2001), 304(2), 237-59

Singing and the processing of auditory information related to song can be affected by experimental manipulations of catecholamine activity in the brain of zebra finches. We investigated, by ... [more ▼]

Singing and the processing of auditory information related to song can be affected by experimental manipulations of catecholamine activity in the brain of zebra finches. We investigated, by immunocytochemistry in the brain of male and female canaries, the distribution of tyrosine hydroxylase (TH), the rate-limiting step in the synthesis of catecholamines. Fibers immunoreactive for TH (TH-ir) were particularly abundant in the lobus parolfactorius, the paleostriatum primitivum, and the nucleus septalis lateralis. A high density of TH-ir basket-like structures was observed in the caudomedial neostriatum, an area involved in song perception and recognition. In most males, a high density of TH-ir fibers outlined the telencephalic song control nuclei including the high vocal center, the nucleus robustus archistriatalis, the nucleus interfascialis, the lateral and medial parts of the magnocellular nucleus of the anterior neostriatum, and area X of the lobus parolfactorius. The higher density of fibers immunoreactive for TH in these nuclei, compared with the surrounding telencephalon, supports the notion that the morphological evolution of the song control nuclei was accompanied by a neurochemical specialization. This specific innervation of the song control regions was, in general, not found in females. The specific presence of high densities of TH-ir fibers in the song system of male canaries and the sex difference of this innervation provide anatomical evidence in support of the claim that dopamine and/or norepinephrine play important roles in the modulation of song learning and production. [less ▲]

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See detailDistribution of uncertainties at the municipality level for flood risk modelling along the river Meuse: implications for policy-making
Pirotton, Michel ULg; Stilmant, Frédéric; Erpicum, Sébastien ULg et al

Conference (2016, April)

Flood risk modelling has been conducted for the whole course of the river Meuse in Belgium. Major cities, such as Liege (200,000 inh.) and Namur (l 10,000 inh.), are located in the floodplains of river ... [more ▼]

Flood risk modelling has been conducted for the whole course of the river Meuse in Belgium. Major cities, such as Liege (200,000 inh.) and Namur (l 10,000 inh.), are located in the floodplains of river Meuse. Particular attention has been paid to uncertainty analysis and its implications for decision-making. The modelling chain contains flood frequency analysis, detailed 2D hydraulic computations, damage modelling and risk calculation. The relative importance of each source of uncertainty to the overall results uncertainty has been estimated by considering several alternate options for each step of the analysis; different distributions were considered in the flood frequency analysis; the influence of modelling assumptions and boundary conditions (e.g., steady vs. unsteady) were taken into account for the hydraulic computation; two different landuse classifications and two sets ofdamage functions were used; the number of exceedance probabilities involved in the risk calculation (by integration of the risk-curves) was varied. In addition, the sensitivity of the results with respect to increases in flood discharges \vas assessed. The considered increases are consistent with a "wet" climate change scenario for the time horizons 202l~2050 and 2071-2100 (Detrembleur et al., 2015). The results of hazard computation differ significantly between the upper and lower parts of the course of river Meuse in Belgium. In the former, inundation extents grow gradually as the considered flood discharge is increased (i.e. the exceedance probability is reduced), while in the downstream part, protection structures (mainly concrete walls) prevent inundation for flood discharges corresponding to exccedance probabilities of 0.01 and above (in the present climate). For higher discharges, large inundation extents are obtained in the floodplains. The highest values of risk (mean annual damage) are obtained in the municipalities which undergo relatively frequent flooding (upper part of the river), as well as in those of the downstream part of the Meuse in which flow depths in the urbanized floodplains are particularly high when inundation occurs. This is the case of the city of Liege, as a result of a subsidence process following former mining activities. For a given climate scenario, the uncertainty ranges affecting flood risk estimates are significant; but not so much that the results for the different municipalities would overlap substantially. Therefore, these uncertainties do not hamper prioritization in terms of allocation of risk reduction measures at the municipality level. In the present climate, the uncertainties arising from flood frequency analysis have a negligible influence in the upper part of the river, while they have a considerable impact on risk modelling in the lower part, where a threshold effect was observed due to the flood protection structures (sudden transition from no inundation to massive flooding when a threshold discharge is exceeded). Varying the number of exceedance probabilities in the integration of the risk curve has different effects for different municipalities; but it does not change the ranking of the municipalities in terms of flood risk. For the other scenarios, damage estimation contributes most to the overall uncertainties. As shown by this study, the magnitude of the uncertainty and its main origin vary in space and in time. This emphasizes the paramount importance of conducting distributed uncertainty analyses. In the considered study area, prioritization of risk reduction means can be reliably performed despite the modelling uncertainties. [less ▲]

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See detailDistribution of varicella-zoster virus and herpes simplex virus in disseminated fatal infections
Nikkels, Arjen ULg; Delvenne, Philippe ULg; Sadzot-Delvaux, Catherine ULg et al

in Journal of Clinical Pathology (1996), 49(3), 243-248

AIMS: To study the cutaneous and visceral distribution of herpes simplex virus (HSV) and varicella zoster virus (VZV) in fatal infections. METHODS: Standard histology, immunohistochemistry (monoclonal ... [more ▼]

AIMS: To study the cutaneous and visceral distribution of herpes simplex virus (HSV) and varicella zoster virus (VZV) in fatal infections. METHODS: Standard histology, immunohistochemistry (monoclonal antibodies VL8 and VL2 and polyclonal antibody IE63 directed against VZV; monoclonal antibodies IBD4 and HH2 and polyclonal antibodies directed against HSVI and HSVII) and in situ hybridisation (anti-HSV and anti-VZV probes) were applied to formalin fixed, paraffin wax sections. RESULTS: On histological examination, Herpesviridae infection was evident in various organs including the lungs, liver and skin. In addition, immunohistochemistry and in situ hybridisation revealed the presence of HSV and VZV antigens and nucleic acids in several cell types and tissues showing no cytopathological alterations suggestive of Herpesviridae infection. The organs with histological evidence of infection also contained VZV or HSV antigens and their genes. CONCLUSIONS: These findings suggest that organ failure in disseminated VZV and HSV infections is primarily caused by HSV or VZV induced cell damage and lysis. They also indicate that immunohistochemistry and in situ hybridisation can provide an accurate, type-specific diagnosis on formalin fixed, paraffin wax embedded tissue even when classic histological and cytological characteristics are lacking. [less ▲]

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See detailDistribution of varicella-zoster virus DNA and gene products in tissues of a first-trimester varicella-infected fetus.
Nikkels, Arjen ULg; Delbecque, Katty ULg; Pierard, Gérald ULg et al

in Journal of Infectious Diseases (2005), 191(4), 540-5

Precise information about varicella-zoster virus (VZV) infection in first-trimester fetuses remains sketchy. After varicella infection was diagnosed in a woman, her 12-week-old fetus was aborted and was ... [more ▼]

Precise information about varicella-zoster virus (VZV) infection in first-trimester fetuses remains sketchy. After varicella infection was diagnosed in a woman, her 12-week-old fetus was aborted and was investigated, by histological examination, virus culturing, polymerase chain reaction, in situ hybridization (ISH), and immunohistochemistry (IHC), for the presence of VZV infection. Only the results of the histological examination suggested the presence of alpha -herpesvirus infection, in the gastrointestinal tract and liver; results of ISH were positive for VZV, and results of IHC staining were positive for intermediate early protein 63 (IE63) but negative for glycoprotein E (gE), in the dorsal root ganglia (DRG), meninges, gastrointestinal tract, pancreas, smooth muscle, liver, and placental trophoblast, indicating the presence of a nonproductive, latency-like VZV infection. Only the gastrointestinal tract and liver exhibited simultaneous staining for IE63 and gE, a result suggesting that active replication of VZV was present. In conclusion, widespread nonproductive VZV infection in the absence of histological clues is an early event in VZV infection in fetuses. The observed gene-expression pattern in most tissues resembles that of latent VZV infection in DRG. Latency-like infection in nonneural cell types may potentially reactivate, leading to multifocal necrosis, fibrosis, and dystrophic calcifications, as observed in advanced congenital varicella syndrome. [less ▲]

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See detailDistribution of varicella-zoster virus gpI and gpII and corresponding genome sequences in the skin
Nikkels, Arjen ULg; Delvenne, Philippe ULg; Debrus, S. et al

in Journal of Medical Virology (1995), 46(2), 91-96

In the course of varicella-zoster virus (VZV) infection, some viral capsid antigens are found in the epidermis and dermis. The aim of this study was to investigate the localisation of two major VZV ... [more ▼]

In the course of varicella-zoster virus (VZV) infection, some viral capsid antigens are found in the epidermis and dermis. The aim of this study was to investigate the localisation of two major VZV glycoproteins (gpI and gpII) and of their respective genes in the skin. The distribution of VZV gpI and II in 27 formalin fixed paraffin embedded skin biopsies from herpes tester eruptions were compared by immunohistochemistry. Double immunostaining was carried our to identify infected cells. The presence of viral nucleic acids coding for gpI and gpII was examined by in situ hybridisation. The distribution of gpI and gpII and their corresponding genome sequences was similar in the epidermis, gpI and gpII were also detected in dermal FXIIIa positive dendrocytes, in Mac 387 and CD68 positive macrophages, and in perineural and endothelial cells. However, the corresponding viral nucleic acids were rarely and barely detected in these cells of the dermis. It is concluded that VZV infection of epithelial cells follows a different course than in dermal cells. (C) 1995 Wiley-Liss, Inc. [less ▲]

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See detailDistribution of vortex lattice melting temperatures in mixed state diagram of Bi2212 tapes
Pekala, M.; Bougrine, Hassan ULg; Gadomski, W. et al

in Physica C (1998), 303(3-4), 169-176

The electrical resistivity in the mixed state of Bi2212 tape superconductors can be accurately reconstructed for values below approximately a half of the normal state value of resistivity, assuming a ... [more ▼]

The electrical resistivity in the mixed state of Bi2212 tape superconductors can be accurately reconstructed for values below approximately a half of the normal state value of resistivity, assuming a Gaussian distribution for the vortex lattice melting temperatures. The magnetic field dependences of the distribution width and of the dB(c2)/dT parameter were calculated. Moreover the vortex liquid viscosity coefficient was determined between the vortex lattice melting temperature and T-c at various magnetic fields. It is pointed out that the vortex lattice melting transition should not be confused with the irreversibility line of magnetic studies nor with the percolation temperature line for electrical resistivity. (C) 1998 Elsevier Science B,V. All rights reserved. [less ▲]

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See detailDistribution patterns and indicator species of butterfly assemblages of wet meadows in southern Belgium
Sawchik, Javier; Dufrêne, Marc ULg; Lebrun, Philippe

in Belgian Journal of Zoology (2005), 135(1), 43-52

Focal species are a valuable tool for proposing and evaluating management practices for biodiversity conservation. Assemblages of indicator species could be used to cover a wide range of habitats. We ... [more ▼]

Focal species are a valuable tool for proposing and evaluating management practices for biodiversity conservation. Assemblages of indicator species could be used to cover a wide range of habitats. We identified the main patterns of variation in butterfly assemblages on a diverse set of wet meadows in southern Belgium. We used multivariate techniques to identify the butterfly assemblages and the species that characterize these habitats. Three main assemblages were identified, based principally on the dominance of five butterfly species : Brenthis ino, Closiana selene, Lycaena helle, Lycaena hippothoe and Proclossiana eunomia. These are indicator species of different habitats structured along a vegetation gradient. This gradient is partially determined by altitude and edaphic factors (base-richness, pH, fertility). We assume that focusing the conservation practices upon these species will promote the preservation of a wide range of organisms inhabiting the wet meadows. [less ▲]

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