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See detailTechnologies du multimédia, de l'Internet et des télécommunications
Van Droogenbroeck, Marc ULg

Learning material (2004)

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See detailAdaptation of the pull-off test for the evaluation of the superficial cohesion of concrete substrates in repair works: analysis of the test parameters
Courard, Luc ULg; Bissonnette, B.

in Materials and Structures (2004), 37(269), 342-350

Concrete repair works involve most of the time the removal of the damaged or contaminated surface layer. It is necessary to assess the effect of that operation (tool, procedure, etc) upon the integrity of ... [more ▼]

Concrete repair works involve most of the time the removal of the damaged or contaminated surface layer. It is necessary to assess the effect of that operation (tool, procedure, etc) upon the integrity of the residual concrete substrate, prior to the placement of the repair material, since it can affect significantly the adhesion of the repair system. This paper summarizes the findings of a study intended to develop a simple test method for that purpose. After a thorough review of the related scientific documentation, it has been decided to adapt the so-called pull-off test, which is commonly used to determine the bond strength of repair products. An experimental program has been conducted to evaluate the influence of various test parameters on the measured cohesion of a reference concrete surface: transfer plate thickness and diameter, core drilling depth, speed of loading, adhesive type and thickness, and number of tests. A multivaried statistical analysis of the test results clearly shows that the plate diameter and core depth are the most significant parameters, presumably with threshold values, and that there exists a synergetic effect between them. Also, a minimum number of tests can be defined based on the standard deviation and required level of confidence of the results. Overall, the test method shows good potential for a sound quantitative evaluation of a concrete surface mechanical integrity prior to repair, provided that the test parameters are selected properly. [less ▲]

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See detailEtude diachronique, à l’aide de la télédétection, de l’évolution du littoral du sud du delta du Fleuve Rouge (Viet Nam)
de Marneffe, Geneviève; Thrinh, Phan Trong; Tan, Mai Thanh et al

in Bannari, Abderrazak; Blasco (Eds.) Les Xèmes Journées Scientifiques du Réseau Télédétection de l'AUF (2004, May 25)

Dans le cadre de la recherche partagée du réseau de télédétection qui réunit les laboratoires de télédétection de Liège et de Hanoï et dans le cadre des accords de coopération entre le Vietnam et la ... [more ▼]

Dans le cadre de la recherche partagée du réseau de télédétection qui réunit les laboratoires de télédétection de Liège et de Hanoï et dans le cadre des accords de coopération entre le Vietnam et la Région Wallonne (Belgique), l'étude de l'évolution du littoral du sud du delta du Fleuve Rouge a été réalisée. Cette étude comprend deux parties: la première consiste en une présentation générale du delta du Fleuve Rouge. Elle analyse surtout les différents facteurs qui influencent fortement la dynamique littorale (vents, houle, marées…). la deuxième partie est l'étude diachronique du littoral du sud du delta du Fleuve Rouge. Elle s'est effectuée en deux phases : d’abord le traitement et l'analyse de photos aériennes et d'images satellitales, ensuite un travail de vérité-terrain. [less ▲]

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See detailA phase-resolved XMM-Newton campaign on the colliding-wind binary HD 152248
Sana, H.; Stevens, I. R.; Gosset, Eric ULg et al

in Monthly Notices of the Royal Astronomical Society (2004), 350(3), 809-828

We report the first results of an XMM-Newton monitoring campaign of the open cluster NGC 6231 in the Sco OB 1 association. This first paper focuses on the massive colliding-wind binary HD 152248, which is ... [more ▼]

We report the first results of an XMM-Newton monitoring campaign of the open cluster NGC 6231 in the Sco OB 1 association. This first paper focuses on the massive colliding-wind binary HD 152248, which is the brightest X-ray source of the cluster. The campaign, with a total duration of 180 ks, was split into six separate observations, following the orbital motion of HD 152248. The X-ray flux from this system presents a clear, asymmetric modulation with the phase and ranges from 0.73 to 1.18 x 10(-12) erg s(-1) cm(-2) in the 0.5-10.0 keV energy band. The maximum of the emission is reached slightly after apastron. The EPIC spectra are quite soft, and peak around 0.8-0.9 keV. We characterize their shape using several combinations Of MEKAL models and power-law spectra and we detect significant spectral variability in the 0.5-2.5 keV energy band. We also perform 2D hydrodynamical simulations using different sets of parameters that closely reproduce the physical and orbital configuration of the HD 152248 system at the time of the six XMM-Newton pointings. This allows a direct confrontation of the model predictions with the constraints deduced from the X-ray observations of the system. We show that the observed variation of the flux can be explained by a variation of the X-ray emission from the colliding-wind zone, diluted by the softer X-ray contribution of the two O-type stars of the system. Our simulations also reveal that the interaction region of HD 152248 should be highly unstable, giving rise to shells of dense gas that are separated by low-density regions. Finally, we perform a search for short-term variability in the light curves of the system and we show that trends are present within several of the 30-ks exposures of our campaign. Further, most of these trends are in good agreement with the orbital motion and provide a direct constraint on the first-order derivative of the flux. In the same context, we also search for long-range correlations in the X-ray data of the system, but we only marginally detect them in the high-energy tail of the signal. [less ▲]

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See detailClient, mon cher Client ?
Van Caillie, Didier ULg

Article for general public (2004)

This short chronicle recalls how it's important that a firm, even small, do know exactly which are the costs really induced by servicing a client and the consequences on the gross margin realized with ... [more ▼]

This short chronicle recalls how it's important that a firm, even small, do know exactly which are the costs really induced by servicing a client and the consequences on the gross margin realized with this client. [less ▲]

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See detailNumerical and analytical investigations on composite sway frames
Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg

in Modern Building Materials, Structures and Techniques (2004, May 19)

A modern design code for composite construction such as Eurocode 4 limits its scope to “non-sway buildings” with efficient bracing systems. Therefore, it gives mainly rules to analyse and to check ... [more ▼]

A modern design code for composite construction such as Eurocode 4 limits its scope to “non-sway buildings” with efficient bracing systems. Therefore, it gives mainly rules to analyse and to check structural elements like beams, columns, slabs and joints. However, in the last years, the construction of taller buildings and larger industrial halls without wind bracing systems is susceptible to make global instability a relevant failure mode, what is not yet covered by Eurocode 4. For three years, in the framework of a European research project funded by the European Community for Steel and Coal (ECSC), in which Liège University was deeply involved, intensive experimental, numerical and theoretical investigations have been carried out. The latter aimed at improving the knowledge in the field of sway composite frames and at developing appropriate design rules. The rotational behaviour of the beam-to-column composite joints is one of the key aspects of the problem to which a special attention has been paid. This paper presents numerical and analytical studies carried out at Liège University, as part of the above European project, with the objective to investigate the behaviour of 2D composite sway frames under static loading. Particular phenomena put into sight through different analyses are illustrated herein. [less ▲]

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See detailControlled free-radical polymerization products using new controlled agents
Vanhoorne, Pierre; Meyer, Rolf-Volker; Detrembleur, Christophe ULg et al

Patent (2004)

A process for the production of polymers by means of pseudo-living free-radical polymerization is disclosed. The process entails (i) reacting a polymerizable vinyl monomer with nitrogen monoxide and at ... [more ▼]

A process for the production of polymers by means of pseudo-living free-radical polymerization is disclosed. The process entails (i) reacting a polymerizable vinyl monomer with nitrogen monoxide and at least one initiator to prepare a free-radical intermediate product, and (ii) polymerizing the intermediate product optionally together with one or more additional monomers and/or with a free-radical initiator. [less ▲]

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See detailThe effect of youth employment quotas on the job finding rates of young people in Belgian
Fonder, Muriel; Lejeune, Bernard ULg

Conference (2004, May 17)

In april 2000, the Belgian federal government launched a special labor market program, whose prominent characteristic was the obligation for companies to occupy in their labor force a certain quota of ... [more ▼]

In april 2000, the Belgian federal government launched a special labor market program, whose prominent characteristic was the obligation for companies to occupy in their labor force a certain quota of young people. Based on a sample of more 100,000 young Walloon job seekers (Wallonia is the French-speaking region of Belgium), the aim of this paper is to evaluate whether or not this program has really improved the youth insertion in the labour market, compared to what would have prevailed in the absence of the program. The effect of the program is evaluated through discrete duration models, and estimated by ‘difference in differences’, looking at the individual trajectory on the labor market of young job seekers, before and after the setting up of the program, for the program target group and for a control group. The empirical results show that the program had a modest positive effect for mid-skilled job seekers, but very little effect for unskilled job seekers. On the other hand, as it could be expected, a strong deadweight effect is observed for the skilled young job seekers. [less ▲]

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See detailMathematical modelling and design of an advanced once-through heat recovery steam generator
Dumont, Marie-Noëlle ULg; Heyen, Georges ULg

in Computers & Chemical Engineering (2004), 28(5), 651-660

The once-through heat recovery steam generator (HRSG) design is ideally matched to very high temperature and pressure, well into the supercritical range. Moreover this type of boiler is structurally ... [more ▼]

The once-through heat recovery steam generator (HRSG) design is ideally matched to very high temperature and pressure, well into the supercritical range. Moreover this type of boiler is structurally simpler than a conventional one, since no drum is required. In a conventional design, each tube plays a well-defined role: water preheating, vaporisation, superheating. Empirical equations are available to predict the average beat transfer coefficient for each region. For once-through applications, this is no more the case and mathematical models have to be adapted to account for the disappearance of the conventional economiser, boiler and superheater. General equations have to be used for each tube of the boiler, and the actual heat transfer condition in each tube has to be identified. The mathematical complexity as well as the number of equations is increased. A thermodynamic model has been selected and implemented to suit very high pressure (up to 240 bar), sub- and supercritical steam properties. Model use is illustrated by two case studies: a 180 bar once-through boiler (OTB) and a conventional boiler superheater and reheater. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailConstruction of a set of vectors allowing inducible production of siRNA in Schizosaccharomyces pombe.
Stroobants, Aurore ULg; Tafforeau, Lionel; Guiguen, Allan et al

Poster (2004, May 14)

RNA interference (RNAi) is a sequence-specific gene silencing mechanism. It is induced by the formation of dsRNA that are recognised by the Dicer complex and processed into 21-23 long oligonucleotides ... [more ▼]

RNA interference (RNAi) is a sequence-specific gene silencing mechanism. It is induced by the formation of dsRNA that are recognised by the Dicer complex and processed into 21-23 long oligonucleotides called siRNA (short interfering RNA). Subsequently, RISC (RNA-Inducing Silencing Complex) binds siRNA that targets the complex towards its homologous mRNA (DYKXHOORN et al., 2003) which is eventually degraded. In contrast to budding yeast, the entire pathway is conserved in the fission yeast Schizosaccharomyces pombe, making it a valuable organism to both study physiological RNAi and to use it as a inducible gene knock-down tool. In an attempt to apply this method in the fission yeast, we are using three different approaches to produce siRNA. In each case, a vector containing a regulatable promoter activated in presence of tetracycline (tTA') (GOSSEN et al., 1995) is generated and the ura4 marker required for growth on medium lacking uracil serves as reporter. First, a vector expressing the full lenght antisens RNA of ura4 (800 nucleotides) (RAPONI and ARNDT, 2003) is used. Second, we are trying to generate much shorter dsRNA where both strands are linked by either a short hairpin of 25 nucleotides (BRUMMELKAMP et al., 2002) or a longer one of 350 nucleotides (SCHRAMKE and ALLSHIRE, 2003). The ability of these different dsRNA to induce silencing of ura4 will be presented. [less ▲]

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See detailDéveloppement d’un projet sportif communal: intérêts et perspectives
Cloes, Marc ULg

Scientific conference (2004, May 14)

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See detailA model for the off-forward structure functions of the pion
Bissey, F.; Cudell, Jean-René ULg; Cugnon, Joseph ULg et al

in Physics Letters B (2004), 587(3-4), 189-200

We extend our model for the pion, which we used previously to calculate its diagonal structure function, to the off-forward case. The imaginary part of the off-forward y*pi -->. gamma*pi scattering ... [more ▼]

We extend our model for the pion, which we used previously to calculate its diagonal structure function, to the off-forward case. The imaginary part of the off-forward y*pi -->. gamma*pi scattering amplitude is evaluated in the chiral limit (m(pi) = 0) and related to the twist-two and twist-three generalised parton distributions H, H-3, (H) over tilde (3). Non-perturbative effects, linked to the size of the pion and still preserving gauge invariance, are included. Remarkable new relations between H, H3 and (H) over tilde (3) are obtained and discussed. (C) 2004 Published by Elsevier B.V. [less ▲]

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See detailQualité de vie et qualité de vie au travail chez des policiers liégeois
Etienne, Anne-Marie ULg; Martel, J.-P.; Dupuis, G.

Conference (2004, May 12)

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See detailBulletin agrométéorologique - Avril 2004
Tychon, Bernard ULg; Ozer, Pierre ULg; Horion, S. et al

in Bulletin Agrométéorologique (2004), 3(1), 1-4

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See detailDelayed and reduced coccolithophorid calcification under elevated PCO2
Delille, Bruno ULg; Harlay, Jérôme ULg; Zondervan, Ingrid et al

Poster (2004, May 10)

Numerous experiments to date have demonstrated that elevated PCO2 is detrimental to biogenic calcification rates. However, most of these experiments have been realized in batch or continuous cultures and ... [more ▼]

Numerous experiments to date have demonstrated that elevated PCO2 is detrimental to biogenic calcification rates. However, most of these experiments have been realized in batch or continuous cultures and give little information on the dynamics of calcification in natural conditions. The present work describes the development and decay of a nutrient-induced bloom of the coccolithophorid Emiliania huxleyi in a mesocosm experiment. The monitoring of Dissolved Inorganic Carbon (DIC) and Total Alkalinity (TAlk) within the seawater enclosures allowed us to describe comprehensively day to day dynamics of both calcification and organic carbon production. Three atmospheric PCO2 conditions (glacial, present and next century) were simulated by bubbling CO2 mixtures, while total alkalinity was left to evolve from its present value. No conspicuous change of Net Community Production under elevated PCO2 was recorded while the production of inorganic carbon appeared to be affected in two ways. Firstly, the production rate of inorganic carbon appeared to be lowered by 40% in the next century PCO2 conditions, decreasing concomitantly the calcification to photosynthesis ratio from 0.75 (glacial conditions) to 0.45 (next century conditions). Secondly, the onset of calcification was delayed by 24~48h under elevated PCO2 conditions, reducing the overall length of calcification in the course of the bloom. These two effects would act to reduce the amount of precipitated CaCO3 by coccolithophorids in a High CO2 world [less ▲]

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See detailBiogeochemical implications of calcification and secondary production of a population of the brittle star Acrocnida brachiata in a temperate coastal ecosystem
Harlay, Jérôme ULg; Gentil, Franck; Davoult, Dominique

Poster (2004, May 10)

The production of organic matter and calcium carbonate by a population of the brittle star Acrocnida brachiata (Echinodermata) was calculated using demographic structure, population density, and relations ... [more ▼]

The production of organic matter and calcium carbonate by a population of the brittle star Acrocnida brachiata (Echinodermata) was calculated using demographic structure, population density, and relations between the size and the ash-free dry weight (AFDW) or the calcimass. During a two-year survey in the Bay of Seine (English Channel, France), one of the four major estuaries affecting the biogeochemical cycling of elements in the southern bight of the North Sea, benthic production of this species amounted to 40.3 g.m-2.yr-1 for AFDW and 80.0 g.m-2.yr-1 for CaCO3. Respiration, based on secondary production, was estimated to be 736 mmol CO2.m-2.yr-1. Using the molar ratio () of CO2 released to CaCO3 precipitated, this biogenic precipitation of calcium carbonate would result in an additional release of 617 mmol CO2.m-2.yr-1. The results of the present study demonstrate that marine calcification should be considered as a significant source of CO2 to seawater and thus a potential source of CO2 to the atmosphere, emphasizing the important role of the biomineralization and dissolution in the carbon budget of temperate coastal ecosystems. This additional biogenic source of CO2 could increase in the future in two ways: firstly, as a positive feedback of  to the rising pCO2 and, secondly, as a positive response to the availability of nutrients due to eutrophication. [less ▲]

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See detailL'enseignement par problème (EPP) et l'apprentissage par problème (APP)
VIERSET, Viviane ULg; Groupe Gypse

Conference (2004, May 06)

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