A two-scale model predicting the mechanical behavior of nanocrystalline solids

in Journal of the Mechanics & Physics of Solids (in press)

Polycrystalline materials, with nanosized grains (<100 nm), exhibit superior strength exceeding those of their coarse-grained counterparts. With such small grains, the deformation mechanisms taking place ... [more ▼]

Polycrystalline materials, with nanosized grains (<100 nm), exhibit superior strength exceeding those of their coarse-grained counterparts. With such small grains, the deformation mechanisms taking place at grain boundaries (GBs) become dominant compared to the intragranular crystal plasticity. Recent studies have revealed that the deformation mechanisms are influenced by the GB network. For instance, a high yield stress in nanostructured metals can be obtained by choosing the relevant grain boundary character distribution (GBCD). In this paper we present an original numerical multiscale approach to predict the mechanical behavior of nanostructured metals according to their GBCD composed of either high angle (HA) GBs (HAB) or low angle (LA) GBs (LAB). Molecular simulations using the quasicontinuum method (QC) are performed to obtain the mechanical response at the nanoscale of GB undergoing simple shear (GB sliding behavior) and tensile loads (GB opening behavior). To simulate the grain behavior, a mechanical model of dislocation motions through a forest dislocation is calibrated using a nanoindentation simulation performed with QC. These QC results are then used in a finite element code (direct numerical simulation-DNS) as a GB constitutive model and as a grain constitutive model. This two-scale framework does not suffer from length scale limitations conventionally encountered when considering the two scales separately. [less ▲]

Snijders’ correction of Infit and Outfit indexes with estimated ability level : an analysis with the Rasch model

in Journal of Applied Measurement (in press)

The Infit mean square W and the Outfit mean square U are commonly used person fit indexes under Rasch measurement. However, they suffer from two major weaknesses. First, their asymptotic distribution is ... [more ▼]

The Infit mean square W and the Outfit mean square U are commonly used person fit indexes under Rasch measurement. However, they suffer from two major weaknesses. First, their asymptotic distribution is usually derived by assuming that the true ability levels are known. Second, such distributions are even not clearly stated for indexes U and W. Both issues can seriously affect the selection of an appropriate cut-score for person fit identification. Snijders (2001) proposed a general approach to correct some person fit indexes when specific ability estimators are used. The purpose of this paper is to adapt this approach to U and W indexes. First, a brief sketch of the methodology and its application to U and W is proposed. Then, the corrected indexes are compared to their classical versions through a simulation study. The suggested correction yields controlled Type I errors against both conservatism and inflation, while the power to detect specific misfitting response patterns gets significantly increased. [less ▲]

La prospective en Wallonie: Une lecture plurielle

in Guyot, Jean-Luc (Ed.) Contribution à une prospective au service de la gouvernance (in press)

Terroir dairy : Using mobile milking robots for special quality dairy products based on site specific grazing

Poster (in press)

An option for combining grazing and automatic milking is Infield Automatic Milking, with more or less mobilie infield automatic milking systems (IAMS) which have been practiced sin 2008 in several ... [more ▼]

An option for combining grazing and automatic milking is Infield Automatic Milking, with more or less mobilie infield automatic milking systems (IAMS) which have been practiced sin 2008 in several European countries. This emerging technology can be used to harvest milk from specific areas, giving specialized dairies the possibility to market concept milk, cheese or butter. [less ▲]

Determination of chloramphenicol in honey, 1 shrimp and poultry meat with liquid chromatography-mass spectrometry. Validation of the method according to Commission Decision 2002/657/EC

in Food Analytical Methods (in press)

Chloramphenicol (CAP) is an antibiotic used for the treatment of bacterial infections in human and veterinary medicine. The use of CAP was prohibited in the European Union in 1994. Control laboratories ... [more ▼]

Chloramphenicol (CAP) is an antibiotic used for the treatment of bacterial infections in human and veterinary medicine. The use of CAP was prohibited in the European Union in 1994. Control laboratories are required to use suitably validated analytical methods to check sample compliance with the regulation. A quantitative method based on liquid chromatography coupled to isotopic dilution tandem mass spectrometry (LC–IDMS/MS) was developed for the determination of chloramphenicol in honey, shrimp and poultry meat. The experimental protocol consisted of a liquid-liquid extraction with ethyl acetate. Separation and detection were realized respectively by a 2690 Waters HPLC (Milford, MA, USA) and a Micromass Triple Quadrupole mass spectrometer (Micromass, Manchester, UK), equipped with an Electrospray source. The effects of mobile phase additives on the response of LC/ESI/MS were examined. Two different HPLC columns were tested: the X-Terra from Waters and the Alltima HP C18 HL from Alltech (Deerfield, IL, USA). A validation of the method was conducted according to the EU criteria for the analysis of chloramphenicol in foods. The decision limits (CCα) were 0.04, 0.03, 0.07 µg kg-1 and the detection capabilities (CCβ) were 0.05, 0.04, 0.08 µg kg-1 for honey, shrimp and poultry meat respectively. Those values are below the minimum required performance limit (MRPL) set at 0.3 µg kg-1 by the EU and 0.1 µg kg-1 by Belgium. Our protocol has the advantage to propose a unique extraction method working as well for honey, shrimp and poultry meat, contrary to similar published methods in which a different extraction method is used for each type of matrix. [less ▲]

Traces and Tracers: Selected papers from the Joint Liège Colloquium on Ocean Dynamics - Bonus- GoodHope - Geotraces meeting

Book published by Elsevier Science (in press)

The Stadium of Olympia, from a dialogical architecture perspective

in Arquitectonics: Mind, Land and Society (in press), 26

The article proposes a renewed interpretation of the relation of the antique stadium of Olympia with its environment. It is argued that the stadium, far from being isolated from the city as commonly ... [more ▼]

The article proposes a renewed interpretation of the relation of the antique stadium of Olympia with its environment. It is argued that the stadium, far from being isolated from the city as commonly admitted, was connected to the Altis through a series of visual relations, adopting principles of dialogical architecture. This argument is illustrated through computer generated perspectives of the stadium. [less ▲]

Démarches participatives et approches quali-quantitatives. Le projet logiciel Mesydel 2012

in Claisse, Frédéric; Laviolette, C.; Reuchamps, M. (Eds.) et al Méthodes participatives appliquées (in press)

Climate and Security: Evidence, Emerging Risks and a New Agenda

in Climatic Change (in press)

Host-habitat location by the parasitoid, Nasonia vitripennis Walker (Hymenoptera: Pteromalidae).

in Journal of Forensic Sciences (in press)

This study investigated the role of odorant cues used during host-habitat location by the generalist parasitoid, Nasonia vitripennis Walker. N vitripennis is a common parasitoid of Dipteran pupae found in ... [more ▼]

This study investigated the role of odorant cues used during host-habitat location by the generalist parasitoid, Nasonia vitripennis Walker. N vitripennis is a common parasitoid of Dipteran pupae found in association with decaying carrion. Behavioral assays were used to investigate the host-habitat searching behavior under different scenarios. First, we demonstrated N. vitripennis to be significantly attracted toward odorant cues associated with decaying meat. The biological activity of nine of the volatile molecules constituting the odor of decaying meat were tested on the searching behavior of parasitoid females through two complementary chemoecological approaches: electronantennography (EAG) and olfactometry bioassays. Butanoic acid and butan-1-ol elicited high olfactory responses, but no attraction was induced by these two chemicals. Behavioral assays showed that, among the VOCs tested, methyldisulfanylmethane (DMDS) was the only volatile chemical to induce attraction in N. vitripennis. [less ▲]