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See detailA coupled electro-thermal Discontinuous Galerkin method
Homsi, Lina ULg; Geuzaine, Christophe ULg; Noels, Ludovic ULg

in Journal of Computational Physics (in press)

This paper presents a Discontinuous Galerkin scheme in order to solve the nonlinear elliptic partial differential equations of coupled electro-thermal problems. In this paper we discuss the fundamental ... [more ▼]

This paper presents a Discontinuous Galerkin scheme in order to solve the nonlinear elliptic partial differential equations of coupled electro-thermal problems. In this paper we discuss the fundamental equations for the transport of electricity and heat, in terms of macroscopic variables such as temperature and electric potential. A fully coupled nonlinear weak formulation for electro-thermal problems is developed based on continuum mechanics equations expressed in terms of energetically conjugated pair of fluxes and fields gradients. The weak form can thus be formulated as a Discontinuous Galerkin method. The existence and uniqueness of the weak form solution are proved. The numerical properties of the nonlinear elliptic problems i.e., consistency and stability, are demonstrated under specific conditions, i.e. use of high enough stabilization parameter and at least quadratic polynomial approximations. Moreover the prior error estimates in the H1-norm and in the L2-norm are shown to be optimal in the mesh size with the polynomial approximation degree. [less ▲]

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See detailStudy of the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal
Diop, Serigne Mbacké; Guèye, Momar Talla; Ndiaye, Ibrahima et al

in International Journal of Biological and Chemical Sciences (in press)

This work aimed to study the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal. The plants were collected in two different localities ... [more ▼]

This work aimed to study the chemical composition of essential oils and floral waters of Cymbopogon citratus (DC.) Stapf (Poaceae) from Senegal. The plants were collected in two different localities, Dakar and Kaolack. The extracts were obtained by steam distillation from both fresh and dried plants and analyses carried out by GC/FID and GC/MS. Oils from Dakar were dominated by geranial which represented 46.0-43.9%, neral 31.8-31.0%, myrcene 10.8-11.7% and geraniol 2.7-4.2% in the fresh and dried plants, respectively. Their floral waters contained mainly 44.6-41.4% geranial, 39.7-35.6% neral and 8.8-13.2% geraniol. The oils from Kaolack were characterized by geranial which constituted 49.5-44.5%, neral 33.3-31.2%, myrcene 7.2-9.6% and geraniol 4.3-6.1% in the fresh and dried plants, respectively. In their floral waters, it is identified 42.8-33.6% geranial, 38.4-27.6% neral and 12.5-24.5% geraniol. This original study revealed that both oils and floral waters of C. citratus from Senegal are characterized by geranial and neral whose repellent properties against mosquitoes are known. [less ▲]

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See detailInfluence of different hydrocolloids on dough thermo-mechanical properties and in vitro starch digestibility of gluten-free steamed bread based on potato flour
Liu, Xingli ULg; Mu, Taihua; Sun, Hongnan et al

in Food Chemistry (in press)

The effects of hydrocolloids (Hydroxypropylmethylcellulose (HPMC), Carboxymethylcellulose (CMC), Xanthan gum (XG), and Apple pectin (AP)) at different concentrations on dough thermo-mechanical properties ... [more ▼]

The effects of hydrocolloids (Hydroxypropylmethylcellulose (HPMC), Carboxymethylcellulose (CMC), Xanthan gum (XG), and Apple pectin (AP)) at different concentrations on dough thermo-mechanical properties and in vitro starch digestibility of gluten-free potato steamed bread were investigated. Results showed that hydrocolloids addition significantly increased the gelatinization temperature (from 52.0 to 64.2 °C) and water absorption (from 56.22 to 66.50 %) of potato dough. Moreover, hydrocolloids may be interacted with protein and starch, the density of potato protein bands was decreased by hydrocolloids addition, the reason might be that higher molecular weight complexes might be formed between proteins-hydrocolloids or proteins-proteins, thus change the protein solubility. Furthermore, steamed breads with hydrocolloids presented higher specific volume and lower hardness, and the rapidly digestible starch and estimated glycemic index were significantly decreased from 45.51 to 20.64, from 69.54 to 55.17, respectively. In conclusion, HPMC and XG could be used as improvers in the gluten-free potato steamed bread. [less ▲]

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See detailX-ray study of bow shocks in runaway stars
De Becker, Michaël ULg; del Valle, M.V.; Romero, G.E. et al

in Monthly Notices of the Royal Astronomical Society (in press)

Massive runaway stars produce bow shocks through the interaction of their winds with the interstellar medium, with the prospect for particle acceleration by the shocks. These objects are consequently ... [more ▼]

Massive runaway stars produce bow shocks through the interaction of their winds with the interstellar medium, with the prospect for particle acceleration by the shocks. These objects are consequently candidates for non-thermal emission. Our aim is to investigate the X-ray emission from these sources. We observed with XMM-Newton a sample of 5 bow shock runaways, which constitutes a significant improvement of the sample of bow shock runaways studied in X-rays so far. A careful analysis of the data did not reveal any X-ray emission related to the bow shocks. However, X-ray emission from the stars is detected, in agreement with the expected thermal emission from stellar winds. On the basis of background measurements we derive conservative upper limits between 0.3 and 10 keV on the bow shocks emission. Using a simple radiation model, these limits together with radio upper limits allow us to constrain some of the main physical quantities involved in the non-thermal emission processes, such as the magnetic field strength and the amount of incident infrared photons. The reasons likely responsible for the non-detection of non-thermal radiation are discussed. Finally, using energy budget arguments, we investigate the detectability of inverse Compton X-rays in a more extended sample of catalogued runaway star bow shocks. From our analysis we conclude that a clear identification of non-thermal X-rays from massive runaway bow shocks requires one order of magnitude (or higher) sensitivity improvement with respect to present observatories. [less ▲]

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See detailFlow field in shallow reservoir with varying inlet and outlet position
Ferrara, Velia; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in Journal of Hydraulic Research (in press)

Shallow reservoirs are used for multiple purposes, such as storm water retention and trapping of sediments. Reliable predictions of the flow fields are necessary to inform the design and operation of ... [more ▼]

Shallow reservoirs are used for multiple purposes, such as storm water retention and trapping of sediments. Reliable predictions of the flow fields are necessary to inform the design and operation of these structures. Using numerical simulations, we performed a systematic analysis of the influence of the location of the inlet and outlet on the flow fields developing in rectangular shallow reservoirs of various sizes. Depending on the relative location of the inlet and outlet with respect to the reservoir centreline, contrasting flow patterns are obtained, involving either no flow reattachment, or a jet reattached on either of the reservoir sidewalls. The results reveal also the occurrence of bi-stable flow configurations, i.e. different steady state flow fields are reached depending on the flow history. This is of high relevance for the design of shallow reservoirs as such configurations should certainly be avoided to achieve a robust hydraulic sizing of the reservoir. [less ▲]

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See detailEfficacy of Basil-Cabbage intercropping to control insect pests in Benin, West Africa
Yarou, Boni Barthélémy ULg; Assogba Komlan, Françoise; Tossou, Eric et al

in Communications in Agricultural and Applied Biological Sciences (in press)

Cabbage (Brassica oleracea L.) is a common vegetable whose production is severely limited by insect pest pressure in Western Africa. This study was conducted during the dry and rainy season in the south ... [more ▼]

Cabbage (Brassica oleracea L.) is a common vegetable whose production is severely limited by insect pest pressure in Western Africa. This study was conducted during the dry and rainy season in the south Benin to evaluate the potential of tropical basil (Ocimum gratissimum L.) for repelling cabbage pests (Hellula undalis Fabricius, Plutella xylostella L. and Spodoptera litto-ralis Boisduval). In a complete randomized block design with four replicates, the insect infestation were compared between three association modalities: (i) cabbage intercropped with tropical basil, (ii) cabbage plots surrounded by tropical basil and (iii) control (no basil in the cabbage area). The presence of tropical basil near cabbage plots significantly reduced insect pest abundance on cabbage. Damages were also less important on cabbage intercropped with tropical basil. Among both intercropping modalities, alternate rows showed the best results in terms of reducing pest populations and damages than compared to cabbage plots surrounded by tropical basil. [less ▲]

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See detailReliability of unipodal and bipodal counter movement jump landings in a recreational male population
Schwartz, Cédric ULg; Forthomme, Bénédicte ULg; Paulus, Julien ULg et al

in European Journal of Sport Science (in press)

Movement patterns during landing have been suggested to be related to injury risk. The purpose of this study was to determine the inter-session reliability of kinematic variables and ground reaction ... [more ▼]

Movement patterns during landing have been suggested to be related to injury risk. The purpose of this study was to determine the inter-session reliability of kinematic variables and ground reaction forces during landing in a population of male recreational athletes after a counter movement jump. Both unipodal and bipodal landings were evaluated. Furthermore, the possibility to improve landing reliability with a verbal instruction was also studied. Twenty- four male volunteers with no history of lower-extremity trauma were randomly assigned to two groups (with and without verbal landing instruction). An optoelectronic 3D system and force plates were used to measure the lower-limb joint angles and the ground reaction forces during landing. Intraclass correlation values show moderate to excellent inter-session reliability for the bipodal task (ICC average: 0.80, range: 0.46 to 0.97) and poor to excellent reliability for the unipodal task (ICC average: >0.75, range: 0.20 to 0.95). However, large standard errors of measurement values at the ankle joint at impact (27.6 ± 11.5°) and for the vertical ground reaction forces (394 ± 1091 N) show that some variables may not be usable in practice. The verbal instruction had a negative effect on the reliability of unipodal landing but improved the reliability of bipodal landing. These findings show that the reliability of a landing task is influenced by its motor complexity as well as the instruction given to the subject. [less ▲]

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See detailMultiple Gas-Phase Conformations of a Synthetic Linear Poly(acrylamide) Polymer Observed Using Ion Mobility-Mass Spectrometry
Haler, Jean ULg; Far, Johann ULg; Aqil, Abdelhafid ULg et al

in Journal of the American Society for Mass Spectrometry (in press)

Ion mobility-mass spectrometry (IM-MS) has emerged as a powerful separation and identification tool to characterize synthetic polymer mixtures and topologies (linear, cyclic, star-shaped ... [more ▼]

Ion mobility-mass spectrometry (IM-MS) has emerged as a powerful separation and identification tool to characterize synthetic polymer mixtures and topologies (linear, cyclic, star-shaped,...). Electrospray coupled to IM-MS already revealed the coexistence of several charge state-dependent conformations for a single charge state of biomolecules with strong intramolecular interactions, even when limited resolving power IM-MS instruments were used. For synthetic polymers, the sample's polydispersity allows the observation of several chain lengths. A unique collision cross-section (CCS) trend is usually observed when increasing the degree of polymerization (DP) at constant charge state, allowing the deciphering of different polymer topologies. In this paper, we report multiple coexisting CCS trends when increasing the DP at constant charge state for linear poly(acrylamide) PAAm in the gas phase. This is similar to observations on peptides and proteins. Biomolecules show in addition population changes when collisionally heating the ions. In the case of synthetic PAAm, fragmentation occurred before reaching the energy for conformation conversion. These observations, which were made on two different IM-MS instruments (SYNAPT G2 HDMS and high resolution multi-pass cyclic T-Wave prototype from Waters), limit the use of ion mobility for synthetic polymer topology interpretations to polymers where unique CCS values are observed for each DP at constant charge state. [less ▲]

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See detailA biased random key genetic algorithm applied to the electric distribution network reconfiguration problem
de Faria Jr., Haroldo; Resende, Mauricio; Ernst, Damien ULg

in Journal of Heuristics (in press)

This work presents a biased random-key genetic algorithm (BRKGA) to solve the electric distribution network reconfiguration problem (DNR). The DNR is one of the most studied combinatorial optimization ... [more ▼]

This work presents a biased random-key genetic algorithm (BRKGA) to solve the electric distribution network reconfiguration problem (DNR). The DNR is one of the most studied combinatorial optimization problems in power system analysis. Given a set of switches of an electric network that can be opened or closed, the objective is to select the best configuration of the switches to optimize a given network objective while at the same time satisfying a set of operational constraints. The good performance of BRKGAs on many combinatorial optimization problems and the fact that it has never been applied to solve DNR problems are the main motivation for this research. A BRKGA is a variant of random-key genetic algorithms, where one of the parents used for mating is biased to be of higher fitness than the other parent. Solutions are encoded by using random keys, which are represented as vectors of real numbers in the interval (0,1), thus enabling an indirect search of the solution inside a proprietary search space. The genetic operators do not need to be modified to generate only feasible solutions, which is an exclusive task of the decoder of the problem. Tests were performed on standard distribution systems used in DNR studies found in the technical literature and the performance and robustness of the BRKGA were compared with other GA implementations. [less ▲]

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See detailPrévalence et risque de maltraitance des aînés à domicile en Wallonie : retour sur un dispositif d’enquête
Nisen, Laurent ULg

in "Vieillir aujourd'hui des mo(n)des recomposés" (in press)

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See detailDe automatische toekenning van rechten in de Belgische sociale bescherming. Stand van zaken en opties voor de toekomst
Buysse, Linde; Goedemé, Tim; Janssens, Julie et al

in Pauvreté en Belgique. Annuaire 2017 (in press)

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See detailStructural Basis for Plant Plasma Membrane Protein Dynamics and Organization into Functional Nanodomains
Gronnier; Crowet, Jean-Marc ULg; Habenstein, Birgit et al

in eLife (in press)

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See detailExperimental and theoretical analysis of shear bolted connections for tubular structures
D'Antimo, Marina ULg; Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg et al

in Journal of Constructional Steel Research (in press)

In this paper, numerical and experimental investigations devoted to the evaluation of the bearing resistance of tubular members with gusset plates and through-all long bolts are presented. Unlike lap ... [more ▼]

In this paper, numerical and experimental investigations devoted to the evaluation of the bearing resistance of tubular members with gusset plates and through-all long bolts are presented. Unlike lap shear joints, the analysed connection evidences a reduced confinement of the bearing area associated to the use of long bolts and the presence of a gap in the member, which can lead, consequently, to a reduction of the bearing resistance. In order to investigate the behaviour of shear connections made up of thin and thick SHS (Square Hollow Section) profiles and long bolts, an experimental test campaign including 24 specimens and FE simulations have been conducted. Both experimental and FE results have confirmed the influence of local instability on the hole in bearing resistance of thin profiles and the poor accuracy of the available standards for this particular joint typology. In particular, the performed comparisons have shown that, for thin profiles, EC3 model is likely to overestimate the resistance, while for higher thickness of the SHS conservative predictions are obtained. The present paper presents the conducted experimental and numerical investigations, highlighting at the end the need for a proper formulation able to account for the local instability effect on the bearing resistance. [less ▲]

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See detailEffects of agricultural land use on fluvial carbon dioxide, methane and nitrous oxide concentrations in a large European river, the Meuse (Belgium)
Borges, Alberto ULg; Darchambeau, F.; Lambert, T et al

in Science of the Total Environment (2018), 610–611

We report a data-set of CO2, CH4, and N2O concentrations in the surface waters of the Meuse river network in Belgium, obtained during four surveys covering 50 stations (summer 2013 and late winter 2013 ... [more ▼]

We report a data-set of CO2, CH4, and N2O concentrations in the surface waters of the Meuse river network in Belgium, obtained during four surveys covering 50 stations (summer 2013 and late winter 2013, 2014 and 2015), from yearly cycles in four rivers of variable size and catchment land cover, and from 111 groundwater samples. Surface waters of the Meuse river network were over-saturated in CO2, CH4, N2O with respect to atmospheric equilibrium, acting as sources of these greenhouse gases to the atmosphere, although the dissolved gases also showed marked seasonal and spatial variations. Seasonal variations were related to changes in freshwater discharge following the hydrological cycle, with highest concentrations of CO2, CH4, N2O during low water owing to a longer water residence time and lower currents (i.e. lower gas transfer velocities), both contributing to the accumulation of gases in the water column, combined with higher temperatures favourable to microbial processes. Inter-annual differences of discharge also led to differences in CH4 and N2O that were higher in years with prolonged low water periods. Spatial variations were mostly due to differences in land cover over the catchments, with systems dominated by agriculture (croplands and pastures) having higher CO2, CH4, N2O levels than forested systems. This seemed to be related to higher levels of dissolved and particulate organic matter, as well as dissolved inorganic nitrogen in agriculture dominated systems compared to forested ones. Groundwater had very low CH4 concentrations in the shallow and unconfined aquifers (mostly fractured limestones) of the Meuse basin, hence, should not contribute significantly to the high CH4 levels in surface riverine waters. Owing to high dissolved concentrations, groundwater could potentially transfer important quantities of CO2 and N2O to surface waters of the Meuse basin, although this hypothesis remains to be tested. [less ▲]

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See detailEdouard Rolin-Jaequemyns (1863-1936). Juriste belge
Genin, Vincent ULg

in Académie royale de Belgique (Ed.) Nouvelle biographie nationale (vol. 14) (2018)

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See detailHenry Solvyns (1817-1894). Diplomate belge
Genin, Vincent ULg

in Académie royale de Belgique (Ed.) Nouvelle biographie nationale (vol. 14) (2018)

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See detailDie Rhetorik des Friedens von Romain Rolland: ein Einfluß von Nietzsche
Franck, Thomas ULg

Conference (2017, November 11)

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See detailAssessment of damage and residual load bearing capacity of a concrete slab after fire: Applied reliability-based methodology
Molkens, Tom; Van Coile, Ruben; Gernay, Thomas ULg

in Engineering Structures (2017), 150

For most fires occurring in buildings with a concrete structural frame, the structural elements do not collapse during fire exposure, and further use of the building after fire may be possible. Fire can ... [more ▼]

For most fires occurring in buildings with a concrete structural frame, the structural elements do not collapse during fire exposure, and further use of the building after fire may be possible. Fire can nevertheless result in a permanent loss of strength and thus a post-fire evaluation of the residual load bearing capacity has to be made to inform decisions on continued use and the need for structural repairs. This evaluation is however particularly difficult due to the many uncertainties associated with both the fire exposure and the characteristics of the structural elements. These uncertainties cannot be neglected when determining the residual capacity since adequate safety is a major societal concern as indicated by the predominance of safety in current design standards and guidance documents. In this paper a comprehensive methodology is presented for the assessment of the residual capacity of concrete structures after exposure to fire. The methodology is introduced through application to a real-life case study of an apartment fire with a focus on the end-span of the affected continuous concrete slab. It results in a reliability-based evaluation of the maximum allowable characteristic value for the imposed load on the slab. The presented methodology is useful to make informed decision about continued use of structures after a fire event. [less ▲]

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See detailAn incremental-secant mean-field homogenization method with second statistical moments for elasto-visco-plastic composite materials
Wu, Ling ULg; Adam, Laurent; Doghri, Issam et al

in Mechanics of Materials (2017), 114

This paper presents an extension of the recently developed incremental-secant mean-field homogenization (MFH) procedure in the context of elasto-plasticity to elasto-visco-plastic composite materials ... [more ▼]

This paper presents an extension of the recently developed incremental-secant mean-field homogenization (MFH) procedure in the context of elasto-plasticity to elasto-visco-plastic composite materials while accounting for second statistical moments. In the incrementalsecant formulation, a virtual elastic unloading is performed at the composite level in order to evaluate the residual stress and strain states in the different phases, from which a secant MFH formulation is applied. When applying the secant MFH process, the Linear-Comparison-Composite is built from the piece-wise heterogeneous residual strain-stress state using naturally isotropic secant tensors defined using either first or second statistical moment values. As a result non-proportional and non-radial loading conditions can be considered because of the incremental-secant formulation, and accurate predictions can be obtained as no isotropization step is required. The limitation of the incremental-secant formulation previously developed was the requirement in case of hard inclusions to cancel the residual stress in the matrix phase, resulting from the composite material unloading, to avoid over-stiff predictions. It is shown in this paper that in the case of hard inclusions by defining a proper second statistical moment estimate of the von Mises stress, the residual stress can be kept in the different composite phases. Moreover it is shown that the method can be extended to visco-plastic behaviors without modifying the homogenization process as the incremental-secant formulation only requires the definition of the secant operator of the different phase material models. Finally, it is shown that although it is also possible to define a proper second statistical moment estimate of the von Mises stress in the case of soft inclusions, this does not improve the accuracy as compared to the increment-secant method with first order statistical moment estimates. [less ▲]

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