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See detailPreparation of stable suspensions of gold nanoparticles in water by sonoelectrochemistry
Aqil, Abdelhafid ULg; Serwas, Harry; Delplancke, J. L. et al

in Ultrasonics Sonochemistry (2008), 15(6), 1055-1061

Stable suspensions of gold nanoparticles in water were prepared with high yield by a novel one-step ultrasound assisted electrochemical process. Various strategies based on the addition of either tailor ... [more ▼]

Stable suspensions of gold nanoparticles in water were prepared with high yield by a novel one-step ultrasound assisted electrochemical process. Various strategies based on the addition of either tailor-made polymers or mixtures of commercially available polymers, in the electrochemical bath have been found successful to avoid nanoparticles aggregation commonly observed by sonoelectrochemistry. α-Methoxy-ω-mercapto-poly(ethylene oxide) or poly(vinyl pyrrolidone)/polyethylene oxide mixtures were able to build up a coalescence barrier around the gold nanoparticles. The results showed that the size of the gold nanoparticles could be easily tuned between 5 nm and 35 nm by simple control of the electrochemical parameters, i.e. the deposition time (TON) from 10 ms to 20 ms. The properties of as-prepared gold nanoparticles were compared to the ones of gold colloids prepared by the more conventional wet nanoprecipitation method using chemical reductive agents. [less ▲]

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See detailPrise en charge de la lombalgie en médecine du travail : Recommandations de bonnes pratiques
Mairiaux, Philippe ULg; Mazina, Déogratias

Report (2008)

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See detailPreliminary design of twin-cylinder engines
Louvigny, Yannick ULg

Master of advanced studies dissertation (2008)

This report deals with the preliminary design of a twin-cylinder engine. The goal of the work is not to make the detailed design of the engine but to draw the main characteristics of each kind of engine ... [more ▼]

This report deals with the preliminary design of a twin-cylinder engine. The goal of the work is not to make the detailed design of the engine but to draw the main characteristics of each kind of engine and to investigate which configuration of twin-cylinder engine matches in the best way to given requirements. A simple model is developed from the motion equations of the rotating and oscillating parts of piston engine. This model allows calculating the values of the inertia forces and moments for each angular position of the crankshaft. Different configurations of single-cylinder and twin-cylinder engines (including in-line or boxer, in-phase or out-of-phase motion of the piston) are considered. All of these configurations are characterized by their own set of forces and moments. As the free forces and moments are responsible for engine vibrations and thus vibrations of the vehicle and its passengers, a set of balancing solutions (modification of the crankshaft, addition of first or second order balance shafts) is considered to reduce these loads. This is the balancing of the engine. Great reductions of forces and moments can be obtained with more or less complex solutions. From a design point of view, the next step is to determine what level of vibration is acceptable and which solutions permit to reach this level. A model of a classical four-cylinder engine is made in order to serve as a reference for the comparison of the different configurations of twin-cylinder engine. In addition to the inertia forces, the combustion of the fuel inside the cylinder produces also forces and moments in the engine. To estimate the total forces and moments created by the engine, the gas pressure force is calculated for each configuration of the engine. The last step of this preliminary design consists in investigating the influence of design parameters that can impact the balancing of the engine. A sensitivity analysis is made with different design parameters of the engine (i.e. the mass of the piston, the mass and length of the connecting rod…) This analysis permits to know, depending of the configuration of the engine, which characteristics will require a greater attention during the design phases. [less ▲]

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See detailEffects of extremely low frequency electromagnétic fields (ELF) on human beings. An electrical engineer viewpoint.
Lilien, Jean-Louis ULg; Dular, Patrick ULg; V Sabariego, Ruth ULg et al

in Revue d'électricité et d'électronique industrielle - tijdschrift voor elektriciteit en industriele elektronika (2008), 3

Since the early seventies, potential health risks from Extremely Low Frequency (ELF) exposure (50 Hz) have been extensively treated in the literature (more than 1000 references registered by WHO1, 2007 ... [more ▼]

Since the early seventies, potential health risks from Extremely Low Frequency (ELF) exposure (50 Hz) have been extensively treated in the literature (more than 1000 references registered by WHO1, 2007). After 30 years of worldwide research, the major epidemiological output is the possible moderate increased risk (by a factor 2) of childhood leukaemia in case of a long exposure to an ambient magnetic flux density (B-field) higher than 0.4 μT. However, this fact has not been confirmed by in vivo and/or in vitro studies. Moreover it has not been validated by any adverse health biological mechanisms neither for adults nor for children. Nobody knows precisely what happens inside the body and what could be a hazardous health effect of the ELF fields at 50 Hz. International recommendations (ICNIRP2) are currently, for general public, not to exceed a B-field of 100 μT (50 Hz) and an E-field of 5 kV/m (50 Hz). The authors are looking for a signal generated in the biological process under electric interactions. Herein, a rough overview of typical values of ELF fields will be presented followed by a brief literature survey on childhood leukaemia and ELF. The potential carcinogenic effect of ELF would be linked to electrical disturbances in cell behaviour. The major concern linking childhood leukaemia and ELF is thus to determine the response of bone marrow cells under ELF fields.With that purpose, transmembrane potential will be targeted and linked to the E-field at that level. This paper is three-folded: First, the electric interactions between ambient ELF fields and the body are studied both qualitatively and quantitatively. Though no adverse health field threshold is defined, a minimum field level is fixed in order to discriminate inherent random noise, in agreement with NIEHS3. This is based on the fact that mechanisms become only plausible under field exposure above a certain strength. Different sources of internal E-field are analysed and classified according to their potential risk. Second, the hypothesis of contact current is detailed. Finally, key actions to undertake are highlighted. Based on the current state of the art and some authors’ own developments, this paper proposes simple low cost modifications of private electrical installations in order to annihilate the major source of potential effects of ELF. Particular emphasis is paid to the situation in Belgium as the authors are part of the BBEMG (see end note) and perform numerous measurements in Belgian residential homes. [less ▲]

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See detailCytokines and chemokines in follicular fluids and potential of the corresponding embryo: the role of granulocyte colony-stimulating fator
Lédée, Nathalie ULg; Lombroso, R.; Lombardelli, L. et al

in Human Reproduction (2008), 23(9), 2001-9

BACKGROUND: The cytokine/chemokine levels of individual follicular fluids (FFs) were measured to determine whether a biomarker could be linked to the developmental potential of the derived embryo. METHODS ... [more ▼]

BACKGROUND: The cytokine/chemokine levels of individual follicular fluids (FFs) were measured to determine whether a biomarker could be linked to the developmental potential of the derived embryo. METHODS: Fluid was collected from 132 individual FFs that were the source of oocytes subsequently fertilized and transferred. In each, a bead-based multiplex sandwich immunoassay (Luminex) was used to measure 28 cytokines and chemokines simultaneously. RESULTS: Significantly higher levels of interleukin (IL-2) and interferon (IFN- ) were detected in FF for embryos that underwent early cleavage. IL-12 was significantly higher in FF corresponding to highly fragmented embryos and the chemokine CCL5 was significantly higher in FF related to the best quality (Top) embryos. The level of granulocyte colony-stimulating factor (G-CSF) in individual FF samples was correlated with the implantation potential of the corresponding embryo. The area under the receiver operating characteristics curve, which distinguished the embryos that definitely led to delivery from those that did not, was 0.84 (0.75–0.90) (P = 0.0001) for FF G-CSF. FF G-CSF was significantly lower in patients older than 36 years compared with those <30-year old. When the FF G-CSF was 20 pg/ml or higher, the ratio between Top and non-Top embryos was significantly higher than for the group with FF G-CSF below 20 pg/ml (45 versus 20.45%, P = 0.007). CONCLUSIONS: Individual FF composition is related to the development of the corresponding in vitro generated embryo and its potential of implantation. Individual FF G-CSF may provide a non-invasive biomarker of implantation that needs to be evaluated together with in vitro observation to select the oocyte, and hence the embryo, to transfer. [less ▲]

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See detailRaw genotypes vs haplotype blocks for genome wide association studies by random forests
Botta, Vincent ULg; Hansoul, Sarah ULg; Geurts, Pierre ULg et al

in Proc. of MLSB 2008, second workshop on Machine Learning in Systems Biology (2008, September)

We consider two different representations of the input data for genome-wide association studies using random forests, namely raw genotypes described by a few thousand to a few hundred thousand discrete ... [more ▼]

We consider two different representations of the input data for genome-wide association studies using random forests, namely raw genotypes described by a few thousand to a few hundred thousand discrete variables each one describing a single nucleotide polymorphism, and haplotype block contents, represented by the combinations of about 10 to 100 adjacent and correlated genotypes. We adapt random forests to exploit haplotype blocks, and compare this with the use of raw genotypes, in terms of predictive power and localization of causal mutations, by using simulated datasets with one or two interacting effects. [less ▲]

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See detailLife and Motion Configuration
Hallot, Pierre ULg; Billen, Roland ULg

Poster (2008, September)

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See detailInvestigation et modélisation des tensions circonférentielles en simulation méridienne
Thomas, Jean-Philippe ULg

Master of advanced studies dissertation (2008)

The computation time and the extraction of useful information remain severe drawbacks to systematic use of modern 3D Navier-Stokes codes in a design procedure of multistage turbomachines. That explains ... [more ▼]

The computation time and the extraction of useful information remain severe drawbacks to systematic use of modern 3D Navier-Stokes codes in a design procedure of multistage turbomachines. That explains why throughflow simulation is still widely used at industrial scale. The main limitation of throughflow is however the need for empirical models to reproduce blade-flow interactions and major 3D flow features. As an alternative, Adamczyk (1984) proposed three averaging operators (ensemble, time and passage) that lead to the average-passage model, linking the unsteady turbulent flow field to a steady flow field in a typical blade passage. This model involves additional terms that respectively bring back the mean effect of turbulence, deterministic unsteadiness and aperiodicity on the mean periodic flow. These terms need to be modelled; it is the closure problem. Harmonic closure, which consists in solving a linearized perturbation system in the frequency domain, revealed to be an efficient method to approximate deterministic stresses (He and Ning, 1998, Stridh, 2005, Vilmin, 2006). A fourth averaging can be performed, a circumferential averaging, giving rise to the throughflow model. Additional terms appear: the so-called circumferential stresses. It has been proven that these terms play an important role in the description of the flow (Jennions, 1986, Perrin, 1995), being at least as considerable as deterministic stresses. Introducing these terms in a throughflow simulation allows to reproduce the averaged 3D steady flow field (Simon, 2007). The purpose of this work is to investigate how far empiricism could be reduced by using the averaged-passage equations of Adamczyk, combined with a harmonic closure strategy. To that aim, in the first part of the work, results of a computation performed with a steady three-dimensional Navier-Stokes code are used to calculate the circumferential stresses. The importance of the latter to bring back the mean eff ect of circumferential non-uniformities, linked to 3D phenomena, is illustrated by injecting them into a throughfow simulation. Then the ability of truncated Fourier series to reproduce the flow and its level of non-uniformity in the core flow and near the hub and shroud walls is detailed. It is finally shown that the harmonic approximated stresses can lead to a good reproduction of local 3D flow features in throughflow simulation and to a better accuracy. In the second part of this work it is proposed to adapt the "Nonlinear Harmonic" method to the throughflow model, where the main non-linear system would be the common throughflow equations and the auxiliary systems would give access to a mean high order information; the circumferential stresses. On the way to the adaptation of this technique to the throughflow model, the work shows that a reformulation of the effect of the blades is needed. The latter cannot appear anymore as numerical local explicit impermeability conditions that could not be supported by Fourier series, needing a continuous circumferential evolution of the flow. To get rid of this issue, the blade effect is replaced by a smooth force field as in the "Immersed Boundary Method" of Peskin. A simple example of an inviscid flow around a cylinder illustrates the preceding developments, coupling the "Nonlinear Harmonic Method" to the "Immersed Boundary Method" in a throughflow model, to bring back the mean e ffect of the circumferential non uniformities into the meridional flow. [less ▲]

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See detailBehind the Scenes of the Discovery of Two Extrasolar Planets: ESO Large Programme 666
Minniti, Dante; Naef, Claudio; Udalski, Andrzej et al

in The Messenger (2008), 133

This is the story of the Large Programme 666, dedicated to discover sub-stellar objects (extrasolar planets and brown dwarfs), and to measure their masses, radii, and mean densities. We hunt selected OGLE ... [more ▼]

This is the story of the Large Programme 666, dedicated to discover sub-stellar objects (extrasolar planets and brown dwarfs), and to measure their masses, radii, and mean densities. We hunt selected OGLE transit candidates using spectroscopy and photometry in the ‘twilight zone’, stretching the limits of what is nowadays possible with the VLT. [less ▲]

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See detailThéorie des erreurs de rectitude et de planéité
Debongnie, Jean-François ULg

Report (2008)

This report is focused on straightness and flatness errors, in a common frame. Starting with the framing of a compact of a 2-D or 3-D space by two parallel hyperplanes, it is first noted that the given ... [more ▼]

This report is focused on straightness and flatness errors, in a common frame. Starting with the framing of a compact of a 2-D or 3-D space by two parallel hyperplanes, it is first noted that the given compact may be replaced by its convex closure. It is then proved that the separation of the framing hyperplanes varies continuously with their common normal vector. From this follows that a minimal separation is reached for a given orientation of the hyperplanes. However, this optimal orientation is not necessary unique. An optimality criterium is obtained, which concerns the number and the position of the contact points of the given surfave with the framing hyperplanes. Finally, a direct method of obtaining the optimum is presented. [less ▲]

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See detailRoof storage systems: Modelling and performance’s comparison
Beckers, Eléonore ULg; Degre, Aurore ULg

Poster (2008, September)

Rainwater runoff problems have become critical in large cities because of the increasing imperviousness of surfaces. Best practices to manage urban runoff improve water infiltration and evaporation ... [more ▼]

Rainwater runoff problems have become critical in large cities because of the increasing imperviousness of surfaces. Best practices to manage urban runoff improve water infiltration and evaporation through green areas establishment and, therefore, natural hydrological cycle restoration. The aim is to evaluate rainwater runoff from different types of roof storage systems and to conclude about their own interests to manage urban runoff production. [less ▲]

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See detailEffect of end connection restraints on the stability of steel beams in bending
Amara, S.; Kerdal, D. E.; Jaspart, Jean-Pierre ULg

in Advanced Steel Construction (2008)

The influence of the end restraint conditions on the lateral-torsional buckling of beams is investigated in detail using finite element method. The paper focuses on the limitation of Eurocode 3 regarding ... [more ▼]

The influence of the end restraint conditions on the lateral-torsional buckling of beams is investigated in detail using finite element method. The paper focuses on the limitation of Eurocode 3 regarding the lateral bending and torsional restraint coefficients kz and kθ of the end supports. Theoretical expressions of the coefficients kz and kθ taking into account the minor axis flexural restraint at the support and the end torsional restraint respectively are presented. The introduction of new coefficients zk and kθ representing the actual support conditions in the expression of the elastic critical moment is suggested. A comparison between the elastic critical moments for various beam cross-sections, lengths and various end restraints, obtained from the finite-element method, and those derived from EC3 ENV method, in which the proposed coefficients zk and kθ are introduced, confirms the reliability of these coefficients that model the end support conditions. [less ▲]

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See detailLife and Motion Configuration
Hallot, Pierre ULg; Billen, Roland ULg

(2008, September)

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See detailNon-competition concerns under the ECMR - An overview
Petit, Nicolas ULg

in Concurrences : Revue des Droits de la Concurrence (2008), 4-2008

This article lists the EC merger cases where noncompetition concerns were raised (industrial policy, social concerns, personal data protection etc.). It summarizes the issues raised by non-competition ... [more ▼]

This article lists the EC merger cases where noncompetition concerns were raised (industrial policy, social concerns, personal data protection etc.). It summarizes the issues raised by non-competition concerns in the ECMR. [less ▲]

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See detailRecent developments on composite connections: behaviour of joints subjected to sagging bending moments and presentation of a free design dedicated software
Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg; Klinkhammer, Ralf et al

in EUROSTEEL 2008, 5th European Conference on Steel and Composite Structures (2008, September)

In Eurocode 4, design rules are suggested for the evaluation of the mechanical properties of structural steel-concrete composite joints (rotational stiffness, resistance and ductility). These rules cover ... [more ▼]

In Eurocode 4, design rules are suggested for the evaluation of the mechanical properties of structural steel-concrete composite joints (rotational stiffness, resistance and ductility). These rules cover situations where the joints are subjected to moments and shear forces, but in hogging regions only. Recently, researches have been conducted on the behaviour of composite joints subjected to sagging bending moments and to combined bending moments and axial loads, types of loadings which appear in composite frame further to a column loss. In the present paper, recent developments allowing to extend the EC4 design rules to joints in sagging regions (loading which can occur, for instance, in sway composite frames) are presented and the proposed method is validated through comparisons with experimental test results. Also, an easy-to-apply design software (which will be freely available), applying the rules recommended in Eurocode 4 in a safe and easy way, is described. [less ▲]

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See detailDevelopment of membranar effects in frame beams: experimental and analytical investigations
Demonceau, Jean-François ULg; Luu, Nguyen Nam Hai; Jaspart, Jean-Pierre ULg

in EUROSTEEL 2008, 5th European Conference on Steel and Composite Structures (2008, September)

Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. According to Eurocodes and some ... [more ▼]

Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under exceptional events. According to Eurocodes and some different other national design codes, the structural integrity of civil engineering structures should be ensured through appropriate measures but, in most of the cases, no precise practical guidelines on how to achieve this goal are provided. A European RFCS project called “Robust structures by joint ductility” has been set up in 2004, for three years, with the aim to provide requirements and practical guidelines allowing to ensure the structural integrity of steel and composite structures under exceptional event through an appropriate robustness. The investigations performed at Liège University, as part of this European project, are mainly dedicated to the exceptional event “Loss of a column in a steel or steel-concrete composite building frame”; the main objective is to develop a simplified analytical procedure to predict the frame response further to a column loss. The development of this simplified procedure is detailed in two complementary PhD theses: the thesis of J.-F. Demonceau and the thesis of H.N.N. Luu. The present paper describes experimental and analytical studies carried out within the first PhD thesis. In particular, a simplified analytical method allowing the prediction of the frame response with account of the membranar effects is described. [less ▲]

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See detailNew simplified analytical method for the prediction of global stability of composite sway frames
Ly, Dong Phuong Lam ULg; Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg

in EUROSTEEL 2008, 5th European Conference on Steel and Composite Structures (2008, September)

In the last years, the construction of taller composite buildings and larger composite industrial halls without wind bracing systems is susceptible to make global instability a relevant failure mode. This ... [more ▼]

In the last years, the construction of taller composite buildings and larger composite industrial halls without wind bracing systems is susceptible to make global instability a relevant failure mode. This one is not yet covered by EC4 [2]. This paper reflects investigations carried out of Liege University on this topic. In particular, an innovative simplified analytical method to predict the ultimate loading factor and the associated collapse mode of composite frames is derived. [less ▲]

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See detailComparison of rodac plates and petrifilm TM to assess the microbial contamination of food-contact surfaces : importance of additives
Deckers, Sylvie; Detry, Jean; Anceau, Christine ULg et al

in Proceedings of the Thirteenth Conference on Food Microbiology (2008, September)

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See detailDevelopment and validation of a reference material for food microbiology using Bacillus cereus spores
Abel Massih, Marleen; Debast, Laurent; Planchon, Viviane et al

in Proceedings of the Thirteenth Conference on Food Microbiology (2008, September)

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See detailHeat recovery and reversible heat pumping potentials in non-residential buildings
Bertagnolio, Stéphane ULg; Lebrun, Jean; Andre, Philippe ULg et al

Conference (2008, September)

Detailed reference viewed: 31 (6 ULg)