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See detailExperimental tests and numerical modelling on eight slender steel columns under increasing temperatures
Franssen, Jean-Marc ULg; Zhao, Bin; Gernay, Thomas ULg

in Li, G.Q.; Jiang, S.C.; Chen, Suwen (Eds.) et al Progress on Safety of Structures in Fire (2014, June 11)

In order to fill the lack of knowledge about slender elements behavior at elevated temperatures,, a European research project called FIDESC4 has been funded by the RFCS. This project involves experimental ... [more ▼]

In order to fill the lack of knowledge about slender elements behavior at elevated temperatures,, a European research project called FIDESC4 has been funded by the RFCS. This project involves experimental testing, parametric numerical analyses and development of simple design rules. The present paper reports the characteristics and the results of the FIDESC4 experimental test campaign performed at the University of Liege on slender steel columns at elevated temperatures. A total of eight columns have been tested, all of them with I shape section. Six columns were made of welded sections (some prismatic and some tapered members) and two columns were with hot rolled sections. The nominal length of the columns was 3 meters with the whole length being heated. The strength of the material (webs and flanges) was measured on sample before the tests. The order of magnitude of the initial geometrical imperfections was recorded. The columns were not restrained against longitudinal thermal elongation. The supports at the ends were cylindrical thus inducing a restrain against rotation in one plane while allowing rotation in the other plane. The allowed direction of rotation was chosen in each test to induce buckling around the strong or the weak axis. The load was applied at ambient temperature and maintained for a period of 15 minutes after which the temperature was increased under constant load. The load was applied concentrically on some tests and with an eccentricity in other tests. The load eccentricity was either applied at both ends, leading to constant bending moment distribution along the length, or at one end only, leading to a triangular bending moment distribution. Heating was applied by electrical resistances enclosed in ceramic pads. The columns and the ceramic pads were wrapped in ceramic wool insulating material. This technique was preferred to gas heating in a standard test furnace because it allows applying a slower and better controlled heating rate and thus obtaining a more uniform temperature distribution in the member. It is also easier to measured lateral displacements of the column. Preliminary blank tests were performed on unloaded specimen in order to determine the heating range to be used later on the loaded columns. The paper will also report on a modification of the heating technique that was applied and improved significantly the uniformity in the temperature distribution. Numerical simulations were performed before the tests using shell elements of the software SAFIR and assumed values of the material properties in order to predict the failure modes. It was essentially crucial to determine whether lateral supports at intermediate levels should be provided in order to ensure failure in the desired direction. Experience showed that the failure modes developed as predicted by the numerical simulations. Besides a thorough description of the experiments, the paper will also present the obtained results in terms of failure mode, ultimate temperature and evolution of longitudinal and transverse displacement. Some information will also be given about the level of detail that has to be used in the numerical model in order to get accurate results at a reasonable price. [less ▲]

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See detailFinancement de la santé et recouvrement des coûts en République Démocratique du Congo: le lourd fardeau des ménages.
Manzambi Kuwekita, Joseph ULg

Scientific conference (2014, June 11)

This study examines the share and allocation of household expenditure in health financing, as presented by the National Health Account figures. These figures are based on a national survey carried out in ... [more ▼]

This study examines the share and allocation of household expenditure in health financing, as presented by the National Health Account figures. These figures are based on a national survey carried out in 2010 among 11,000 households, 2,200 people living with HIV/AIDS, 183 institutions, 42 mutual funds, 18 companies and using the balance sheets of 1,300 companies. Total household health expenditure per capita per year amounted to U.S. $ 4.50. Routine health expenditure is covered by the households (40%) and international cooperation (45%) through direct payment without cost sharing (93.7%). A hospital stay is warranted in case of nutritional deficiencies (34%), malaria (12%) and mental disorders (10%). 82% of outpatient care is related to malaria (71%) and mental disorders (12.5 %). In conclusion, the observation that 71.58% of hospitals expenditure, 96.49% of ambulatory care centres expenditure, 98.48% of medical and diagnosis laboratories expenditure, 72.42% of pharmacies expenditures come from households’ out of pocket expenses calls for the establishment of solidarity mechanisms in the health sector. Outpatient malaria care consumes as much as 71% of household expenditure, and we therefore need to strengthen prevention, treatment and focus on monitoring progress. The fact that nutritional deficiencies are the leading cause of people seeking hospital care suggests that efforts are needed to improve their living conditions of households. Mental disorders are the third leading cause of hospital recourse and this pathology should therefore be included in the minimum and supplementary package of activities. [less ▲]

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See detailHigher Symmetries of the conformal Laplacian
Radoux, Fabian ULg

Conference (2014, June 09)

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See detailFast Ambient Pressure Thermal cycling of space solar arrays samples under equivalent AM0 illumination conditions
Guiot, Marc ULg; Fernandez Lisbona, Emilio; Witteveen, Bob et al

Conference (2014, June 08)

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See detailEffects of tillage practices and crop residue exportation on earthworm communities and soil physico-­chemical properties in silt loam arable soil (Belgium)
Lemtiri, Aboulkacem ULg; Colinet, Gilles ULg; Alabi, Taofic ULg et al

Poster (2014, June 08)

Earthworms are known to play integral roles in soils, and are often referred to as vital soil and ecosystem engineers due to their capacity to influence a wide range of chemical, physical, and biological ... [more ▼]

Earthworms are known to play integral roles in soils, and are often referred to as vital soil and ecosystem engineers due to their capacity to influence a wide range of chemical, physical, and biological properties of soil environments. Therefore, it is important to understand how earthworm communities are impacted by tillage systems and crop management practices. In the present study, earthworm and soil samples were collected from wheat cultivated fields in Gembloux, Belgium under the following four experimental treatments: (1) conventional tillage with crop residues left in the soil (CT/IN); (2) conventional tillage with crop residues removed from the field (CT/OUT); (3) reduced tillage with crop residues left in the soil (RT/IN); and (4) reduced tillage with crop residues removed from the field (RT/OUT). The different tillage systems were applied for four consecutive years prior to the initiation of the current study. Results indicated soil compaction was significantly higher in RT compared with CT up to a depth of 6–49 cm. Significant differences were not detected between residue incorporation depth systems, where results showed mean earthworm abundance was respectively 182.25 and 180 individuals.m-2 in CT and RT. Mean earthworm biomass was similarly not significantly different between CT and RT, where results were respectively 48.52 and 57.27 g.m-2. However, a significant difference was observed between IN and OUT treatments, suggesting the exportation of wheat residues will limit earthworm abundance and biomass in CT and RT plots. Data showed high representation of the endogeic earthworm ecological category, notably N. c. caliginosus regardless of treatment. Despite tillage system and exportation of crop residues, N. c. caliginosus, L. terrestris, and A. r. rosea exhibited high abundance, indicating tolerance to soil environmental conditions. For each depth, measures of soil physico-chemical properties showed significant differences among treatments. Furthermore, soil chemical property attributes were significantly higher in the first soil centimetres compared to lower soil layers. These results were attributable to earthworm activity and wheat residues, suggesting earthworms contributed to nutrient dynamics, particularly at increased soil depths. Overall, the results emphasise the influence of exportation of crop residues on earthworm community and also, the important influence of earthworm activity on soil physico-chemical properties change, processes which are closely linked. [less ▲]

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See detailMuti-scale methods with strain-softening: damage-enhanced MFH for composite materials and computational homogenization for cellular materials with micro-buckling
Wu, Ling ULg; Nguyen, Van Dung ULg; Adam, Laurent et al

Conference (2014, June 06)

In this work, multi-scale methods with strain softening are developed in the contexts of damage modeling for composite laminates and of buckling analyses in cellular materials. First, an anisotropic ... [more ▼]

In this work, multi-scale methods with strain softening are developed in the contexts of damage modeling for composite laminates and of buckling analyses in cellular materials. First, an anisotropic gradient–enhanced continuum damage model is embedded in a mean–field homogenization (MFH) process for elasto-plastic composites. The homogenization procedure is based on the newly developed incremental secant mean-field homogenization formulation, for which the residual stress and strain states reached in the phases upon a fictitious elastic unloading are considered as starting point to apply the secant method. The mean stress fields in the phases are then computed using isotropic secant tensors, which are naturally used to define the Linear Comparison–Composite The resulting multi– scale model is then applied to study the damage process at the meso–scale of laminates, and in particular the damaging of plies in a composite stack. By using the gradient–enhanced continuum damage model, the problem of losing uniqueness upon strain softening is avoided. Second, an efficient multi–scale finite element framework capturing the buckling instabilities in cellular materials is developed. As a classical multi–scale computational homogenization scheme loses accuracy with the apparition of the macroscopic localizations resulting from the micro–buckling, the second order multi–scale computational homogenization scheme is considered. This second–order computational framework is enhanced with the following novelties so that it can be used for cellular materials. At the microscopic scale, the periodic boundary condition is used because of its efficiency. As the meshes generated from cellular materials exhibit a large void part on the boundaries and are not conforming in general, the classical enforcement based on the matching nodes cannot be applied. A new method based on the polynomial interpolation2 without the requirement of the matching mesh condition on opposite boundaries of the representative volume element (RVE) is developed. Next, in order to solve the underlying macroscopic Mindlin strain gradient continuum of this second–order scheme by the displacement–based finite element framework, the treatment of high order terms is based on the discontinuous Galerkin (DG) method to weakly impose the C1-continuity. Finally, as the instability phenomena are considered at both scales of the cellular materials, the path following technique is adopted to solve both the macroscopic and microscopic problems. [less ▲]

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See detailOn-the-fly domain adaptation of binary classifiers
Pierard, Sébastien ULg; Marcos Alvarez, Alejandro ULg; Lejeune, Antoine ULg et al

in 23rd Belgian-Dutch Conference on Machine Learning (BENELEARN) (2014, June 06)

This work considers the on-the-fly domain adaptation of supervised binary classifiers, learned off-line, in order to adapt them to a target context. The probability density functions associated to ... [more ▼]

This work considers the on-the-fly domain adaptation of supervised binary classifiers, learned off-line, in order to adapt them to a target context. The probability density functions associated to negative and positive classes are supposed to be mixtures of the source distributions. Moreover, the mixture weights and the priors are only available at runtime. We present a theoretical solution to this problem, and demonstrate the effectiveness of the proposed approach on a real computer vision application. Our theoretical solution is applicable to any classifier approximating Bayes' classifier. [less ▲]

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See detailDesign and fabrication of an electrode array sensor for probing the electric potential distribution at the mesoscopic scale in antistatic felts
Boutaayamou, Mohamed ULg; Lemaire, Philippe; Vanderheyden, Benoît ULg et al

in Measurement Science and Technology (2014), 25

We present an original voltage probe design for measuring the electric potential distribution at the mesoscopic scale (i.e., 1 mm–1 cm) in antistatic felts. The felts are composed of a mixture of non ... [more ▼]

We present an original voltage probe design for measuring the electric potential distribution at the mesoscopic scale (i.e., 1 mm–1 cm) in antistatic felts. The felts are composed of a mixture of non-conductive and metallic fibers and exhibit complex nonlinear electric behavior—including possibly nonlinearity and hysteresis effects—which may be due to localized electrical or electromechanical phenomena. The sensor consists of an array of 8 × 9 needle electrodes (phgr 160 µm at the shaft and less than phgr 50 µm toward the apex), which are mechanically maintained at fixed relative positions while their tips are inserted inside the fabric of the sample. The interelectrode distance is 1.5 mm and the overall active area is 12 × 12 mm². The electrical insulation resistance for nearest neighbor pairs of electrodes was found to be larger than 860 GΩ, thus making the sensor suitable for measuring antistatic felts with an electric resistance that typically does not exceed a few GΩ. The sensor was successfully used for measuring the distribution of the electric potential in a polyester fabric subjected to voltages of up to 6.2 kV, and in a sample containing 2% in weight of metallic fibers, demonstrating the presence of irreversible changes in that felt sample (i.e., with conductive fibers) at high voltages. It is concluded that the developed probe voltage is a promising technique that could be used for the assessment of the conduction mechanisms in the antistatic materials at the mesoscopic scale. [less ▲]

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See detailHydrogéologie et grands travaux du Génie Civil - Hydrogeologie en grote civieltechnische werken
Schroeder, Christian; Huysmans, Marijke; Dassargues, Alain ULg

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in België - Aquifères & eaux souterraines en Belgique (2014)

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See detailComparison between wind speed observed at 100m height and wind speeds simulated by the WRF and MAR models
Doutreloup, Sébastien ULg; Fettweis, Xavier ULg; Erpicum, Michel ULg et al

Poster (2014, June 06)

In the context of FLEXIPAC project funded by "RELIABLE" program of Walloon Region (Belgium), the Laboratory of Climatology and Topoclimatology (LCT) of the University of Liège (Belgium) aims to adjust the ... [more ▼]

In the context of FLEXIPAC project funded by "RELIABLE" program of Walloon Region (Belgium), the Laboratory of Climatology and Topoclimatology (LCT) of the University of Liège (Belgium) aims to adjust the WRF regional model (v.3.4.) forced by ERA-Interim model. Our analysis shows that wind speeds at 100m height simulated by WRF are systematically overestimated compared to wind speeds extracted from wind productions of two wind farms. In order to identify this problem, four comparisons were performed in this contribution. Firstly, we compare WRF model with reanalysis based forcing model. Secondly, we compare two WRF simulations, where one of them has a more precise spatial resolution. Thirdly, we smooth WRF outputs in time (6-hr running mean) in order to study the accuracy of the 30-min variability generated by WRF model. Finally, we comp compare the WRF model with the MAR (v3.3.) regional model using the same forcing at its lateral boundaries. This last one seems to suggest that the MAR model better simulates wind speeds at 10m and at 100m than WRF model and then that wind speed underestimation by WRF is well linked to the WRF physics itself. [less ▲]

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See detailGéothermie de très basse température
Dassargues, Alain ULg; Wildemeersch, Samuel ULg

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in België - Aquifères & eaux souterraines en Belgique (2014)

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See detailIntroduction générale et description du contexte hydrogéologique en Belgique - Algemene inleiding en beschrijving van de hydrogeologische context in Belgïe
Walraevens, Kristine; Biron, Jean-Paul; Dassargues, Alain ULg

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in België - Aquifères & eaux souterraines en Belgique (2014)

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See detailGraviers de la Meuse (alluvions modernes et anciennes) en Wallonie
Dassargues, Alain ULg; Wildemeersch, Samuel ULg; Rentier, Céline

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in België - Aquifères & eaux souterraines en Belgique (2014)

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See detailRemontées des nappes dans les anciens travaux miniers et activités de démergement - Modélisation hydrogéologique spécifique et exemple de la zone minière de Cheratte
Dassargues, Alain ULg; Wildemeersch, Samuel ULg; Orban, Philippe ULg et al

in Dassargues, Alain; Walraevens, Kristine (Eds.) Watervoerende lagen & grondwater in Belgïe – Aquifères & eaux souterraines en Belgique (2014)

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See detailRole of transcription factor sox4b in the differentiation of pituitary cells in zebrafish.
Quiroz O' Donova, Yobhana ULg

Doctoral thesis (2014)

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and ... [more ▼]

The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and terminal differentiation of specific cell types is still not fully understood. The SRY-like HMG-box (SOX) transcription factor Sox4 plays important roles in many developmental processes and has two homologs in zebrafish, Sox4a and Sox4b. We show that the sox4b gene is expressed in the pituitary anlagen starting at 24hpf and later in the entire head region including the pituitary. At 48hpf, sox4b mRNA colocalizes with that for thyroid stimulating hormone (tsh), glycoprotein subunit  (gsu) and the Zn finger transcription factor Gata2a. Loss of Sox4b function, using morpholino knock-down or expression of a dominant negative Sox4 mutant, leads to a drastic decrease in tsh and gsu expression and reduced levels of gh, while other anterior pituitary gland markers including prl, slβ, pomc and lim3 are not affected. Sox4b is also required for expression of gata2a in the pituitary. Knockdown of gata2a leads to decreased tsh and gsu expression at 48hpf, similar to sox4b morphants. Injection of gata2a mRNA into sox4b morphants rescued tsh and gsu expression in thyrotrope cells. Finally, sox4b or gata2a knockdown causes a significant decrease of gonadotropin expression (lhβ and fshβ) at 4dpf. In summary, our results indicate that Sox4b is expressed in zebrafish during pituitary development and plays a crucial role in the differentiation of thyrotrope and gonadotrope cells through induction of gata2a expression in the developing pituitary. [less ▲]

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See detailBiorefine: Recovery of nutrients and metallic trace elements from different wastes by chemical and biochemical processes
Tarayre, Cédric ULg; Fischer, Christophe ULg; De Clercq, Lies et al

Conference (2014, June 05)

At present, most waste processing operations are not oriented towards the valorization of valuable reusable components such as nitrogen, phosphorus, potassium and even Metallic Trace Elements (MTEs ... [more ▼]

At present, most waste processing operations are not oriented towards the valorization of valuable reusable components such as nitrogen, phosphorus, potassium and even Metallic Trace Elements (MTEs). Currently, sewage sludge, for example is usually used as a fertilizer in agriculture, in energy production or in the field of construction. Ashes originating from sludge incineration contain heavy metals and minerals in large quantities. Manure is mainly used in agriculture, although considerable amounts of nutrients are lost and cause pollution. Digestate is also used in agriculture, but other alternatives have been proposed, such as the energetic valorization. Better valorization of these wastes in agriculture (or other sectors) is however largely constrained by a multitude of legal requirements. An important problematic point is the concentration in MTEs that is found in those wastes. Consequently, recovery of nutrients and MTEsmay be a key solution for optimal valorization of wastes. Many unit operations used in the field of chemical and biochemical engineering (mechanical operations on fluids, solids, mass and heat transfers, chemical reactions, etc.) could be used in order to achieve an efficient recovery yield of nutrients and trace elements. The aim of the BioRefine Project is to make an inventory of all recovery techniques of nutrients and MTEs in five countries: Belgium, France, Germany, United Kingdom and The Netherlands. Pilot plants will also be tested to assess the efficiency of new treatment techniques after which the most efficient processes will be chosen to be applied on a larger scale. In addition, the collected data will be used to propose exploitation scenarios taking into account legal constraints and optimized logistics.This work is supported through an INTERREG IVB NWE programme(ref. 320J-BIOREFINE). [less ▲]

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See detailExploration du récit de vie d’adolescents
Poudat, Céline; Boulard, Aurore ULg

in Née, Emilie; Daube, Jean-Michel; Valette, Mathieu (Eds.) et al Proceedings-actes des 12èmes journées d'analyse statistique de données textuelles (2014, June 05)

The present paper follows on from the research we presented in previous JADT (Boulard, Poudat, Gauthier 2012). We still focus on the development of narrative competence (Habermas et Bluck 2000) in ... [more ▼]

The present paper follows on from the research we presented in previous JADT (Boulard, Poudat, Gauthier 2012). We still focus on the development of narrative competence (Habermas et Bluck 2000) in children and adolescents. Although children develop narrative skills, life narratives only emerge in adolescence. On the basis of a corpus made of spontaneous oral speech, we had empirically demonstrated that pre-adolescents aged of 12 had developed stabilized narrative skills enabling them to produce life narratives. Here, we propose a first exploration of the overall structure of adolescent life stories, thanks to a corpus of 268 oral self narratives completed with a questionnaire. [less ▲]

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See detailThe application of the NSGA-II optimization method in designing control charts
Faraz, Alireza ULg; Heuchenne, Cédric ULg; Seif, Asghar

Scientific conference (2014, June 04)

The problem of designing control chart is formulated as a multi-objective optimization problem with the adjusted average time to signal as the statistical objective and the expected cost per hour as the ... [more ▼]

The problem of designing control chart is formulated as a multi-objective optimization problem with the adjusted average time to signal as the statistical objective and the expected cost per hour as the economic objective. Then we try to find the Pareto-optimal designs in which the two objectives are minimized simultaneously by using the elitist non-dominated sorting genetic algorithm method. Through an illustrative example, the advantages of the proposed approach is shown by providing a list of viable optimal solutions and graphical representations, thereby bolding the advantage of flexibility and adaptability. [less ▲]

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