References of "Lebeau, Frédéric"
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See detailUse of on-line flow cytometry for the characterization of microbial stress dynamics during the bioprocess
Brognaux, Alison ULg; Han, Shanshan; Sorensen, Soren et al

Conference (2014, April 03)

Microbial cell population heterogeneity is now recognized as a major source of issues for the development and optimization of bioprocesses. Flow cytometry is a very powerful tool for the follow up of ... [more ▼]

Microbial cell population heterogeneity is now recognized as a major source of issues for the development and optimization of bioprocesses. Flow cytometry is a very powerful tool for the follow up of physiological properties of microbial cells in process-related conditions at the single cell level, and can be used to study the dynamics of segregation directly in bioreactors. In this context, specific interfaces have been developed in order to connect flow cytometer (FC) directly on bioreactor for automated analyses. In this work, we propose a simplified version of such interface and demonstrated its usefulness for multiplexed experiments. This automated FC system has been tested for the follow up of the dynamics of an E. coli pfis::gfpAAV fluorescent bio-reporter and its PI uptake, correlated with membrane permeability. This bioreporter is composed of a fis promoter, a growth dependent promoter-indicator of the nutrient status of cells, fused to a gene expressing an unstable variant of GFP. The results obtained showed that the dynamics of the GFP synthesis is complex and can be attributed to a complex set of biological parameters. Segregation in the membrane permeability has been noticed. This work demonstrates that a simplified version of on-line FC can be used at the process level for the investigation of the dynamics of complex physiological mechanisms. [less ▲]

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See detailImpact des matériaux biosourcés sur le climat intérieur : Un outil de calcul flexible à l'échelle de la pièce
Dubois, Samuel ULg; Lebeau, Frédéric ULg

Conference (2014, March 19)

L'impact de l'utilisation de matériaux d'origine végétale sur le climat intérieur, et donc sur le confort des occupants ainsi que la performance énergétique du bâtiment, n'est établi que partiellement ... [more ▼]

L'impact de l'utilisation de matériaux d'origine végétale sur le climat intérieur, et donc sur le confort des occupants ainsi que la performance énergétique du bâtiment, n'est établi que partiellement. Ces produits présentent des propriétés hygroscopiques et capillaires causant des phénomènes spécifiques liés aux changements de phase dynamiques au sein de la matrice poreuse. Les modèles mathématiques utilisés pour étudier leur comportement hygrothermique de manière détaillée sont souvent des modèles de paroi (dits modèles HAM - Heat Air Moisture). Cela sous-tend qu'ils nécessitent d'imposer des conditions aux limites à toutes les frontières de l'élément étudié, et ne permettent donc pas de connaître les flux de chaleur et de masse réels qu'offrent l'assemblage de matériaux vers le volume d'air intérieur. Pour y accéder, il convient d'intégrer ces modèles à la description de bilans thermique et hydrique de zones. Dans cette communication, nous présentons un modèle hygrothermique capable de simuler l'évolution temporelle du climat intérieur d'une ou de plusieurs pièces ("zones thermiques"). Il est composé d'un module HAM basé sur des équations aux dérivées partielles et caractérisant les transferts dans les matériaux de construction et développé au sein de l'environnement numérique COMSOL Multiphysics. Les équations qui le composent sont flexibles et facilement adaptables au cas expérimental modélisé ainsi qu'aux propriétés des matériaux composant les parois. En outre, on y trouve un traitement complet des phénomènes de changement de phase qui prend en compte l'impact de la température sur la capacité de stockage d'humidité du matériau. Ce premier module, est couplé à un outil caractérisant les bilans chaleur/masse au niveau de la zone à l'aide d'équations aux dérivées ordinaires. Le couplage des modèles est effectué au sein de SIMULINK, un outil de MATLAB destiné à l'étude des systèmes dynamiques. Nous appliquons ensuite ce modèle à l'étude d'un mur en ballots de paille séparant une enceinte climatique de grande taille en deux volumes d'air. Les données d'une expérience simple, un choc thermique imposé à un des volumes d'air, sont comparées aux sorties du modèle numérique. [less ▲]

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See detailUse of on-line flow cytometry for the characterization of microbial stress dynamics during the bioprocess
Brognaux, Alison ULg; Han, Shanshan; Sorensen, Soren et al

Poster (2014, February 07)

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See detailAnalyzing relationships between cattle grazing behavior and pasture attributes using the inertial measurement unit of a mobile phone.
Andriamandroso, Andriamasinoro ULg; Lebeau, Frédéric ULg; Bindelle, Jérôme ULg

Poster (2014, February 07)

The recent technological developments are boosting the opportunities of accurate method to monitor resource use efficiency in agriculture and in their wake, precision livestock farming (PLF) has ... [more ▼]

The recent technological developments are boosting the opportunities of accurate method to monitor resource use efficiency in agriculture and in their wake, precision livestock farming (PLF) has experienced huge developments over the past decade. These developments focus on the optimization of individual performances of farm animals as opposed to herd management. The aim of this paper is to explore a method to detect accurately and to analyze changes in cattle's behaviors on pasture during grazing time using signals from the inertial measurement unit (IMU) of mobile devices as a possible tool to manage individual grazing behavior. Commercial iPhones or iPods, which include a 3-axis accelerometer, a gyroscope and a GPS sensor, are fitted on a halter and placed on the neck of grazing cows. The acquired IMU data are recovered using an open source application (Sensor Data, Wavefrontlabs) and analyzed in a “white-box” model of the cows’ movements. First results using time-domain analysis allowed the detection of grazing behaviors showed accuracies ranging between 84% and 96%, attesting the relevancy of the method. Refined signal processing method will improve the detection but will also inform more about the relative link between the behaviors and the pasture attributes such as sward height, composition and nutritive value. [less ▲]

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See detailContribution of Spray Droplet Pinning Fragmentation to Canopy Retention
Boukhalfa, Hassina dite Hafida ULg; Massinon, Mathieu ULg; Belhamra, Mohamed et al

in Crop Protection (2014), 56

Drop behaviour during impact affects retention. The increase of adhesion is usually seen as the objective when applying crop protection products, while bouncing and shattering are seen as detrimental to ... [more ▼]

Drop behaviour during impact affects retention. The increase of adhesion is usually seen as the objective when applying crop protection products, while bouncing and shattering are seen as detrimental to spray retention. However, observation of drop impacts on barley (Hordeum vulgare L.) using high speed shadowgraphy shows that bouncing and fragmentation can occur in Cassie-Baxter as well as in Wenzel wetting regimes. In this last regime, a part of the drop may remain stuck on the surface, contributing to retention. Using simultaneous measurements of drop impacts with high speed imaging and of retention with fluorophotometry for spray mixtures on excised barley leaves using a Teejet 11003 nozzle at 0.2 MPa, it is observed that about 50% of the drops that fragmented in the Wenzel state remain on the horizontal leaf. Depending on the spray mixture, these impact outcomes accounted for 28 to 46% of retention, the higher contribution being correlated with bigger VMD (Volume Median Diameter). This contribution is not negligible and should be considered when modelling spray retention processes. [less ▲]

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See detailAgricultural spray measurement by high-speed shadow imagery
De Cock, Nicolas ULg; Massinon, Mathieu ULg; Lebeau, Frédéric ULg

Scientific conference (2014, January 10)

Spray characteristics determine treatment performance and environmental contamination. Shadowgraphy associated with high-speed imaging presents an attractive option for measuring drop velocity and size ... [more ▼]

Spray characteristics determine treatment performance and environmental contamination. Shadowgraphy associated with high-speed imaging presents an attractive option for measuring drop velocity and size simultaneously. This study presents an overview of the contrast problems occurring when using backlighted images and proposes appropriate solutions for reliable and quality measurements. Drop diameter measurement is based on the area inside the sub-pixel contour assuming a circular shape. Drop velocity is determined by tracking a drop on two successive images taking into account the drop size, speed limits and the general flow direction. Then, the drop size distribution is corrected taking in account the sampling rate of each drop. Finally, a comparison between PDA and shadowgraphy measurements realized simultaneously on the same spray location is presented. [less ▲]

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See detailSpray retention assment combining high-speed shadow imagery and fluorescence techniques
Massinon, Mathieu ULg; Boukhalfa, Hassina dite Hafida ULg; Lebeau, Frédéric ULg

in International Advances in Pesticide Application: Aspects of Applied Biology 122, 2014 (2014, January 08)

Droplet behaviour during impact affects retention by leaves. The increase of droplet adhesion to plant leaves is the objective when applying crop protection products, while droplet bouncing and ... [more ▼]

Droplet behaviour during impact affects retention by leaves. The increase of droplet adhesion to plant leaves is the objective when applying crop protection products, while droplet bouncing and fragmentation are usually seen as detrimental to spray retention. However, observation of droplet impacts on barley using high speed imaging showed that fragmentation impact outcome can occur in two different wetting regimes: Cassie-Baxter or Wenzel’s regime. In the latter, a fraction of the droplet is anchored in the surface roughness, what contributes to retention. Three mixtures were sprayed on excised barley leaves with an 11003 flat-fan nozzle operating at 0.2 MPa. Simultaneous measurements were performed using high speed imaging for droplet impact characterisation. A fluorescent tracer was added to the spray mixture for retention assessment. Retention was related to impact type considering the fraction of the droplet remaining on the leaf surface after a droplet splashing occurring in Wenzel’s wetting regime. This fraction varied from 28‒46% depending on the spray mixture and was correlated to the Volume Median Diameter DV0.5 of the impacting droplets. [less ▲]

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See detailThe effect of surface orientation on spray retention
Massinon, Mathieu ULg; Boukhalfa, Hassina dite Hafida ULg; Lebeau, Frédéric ULg

in Precision Agriculture (2014)

Research in precision spraying investigates the means to reduce the amount of herbicide applied by directing droplets more accurately towards the weeds. The trend in the development of spot spraying ... [more ▼]

Research in precision spraying investigates the means to reduce the amount of herbicide applied by directing droplets more accurately towards the weeds. The trend in the development of spot spraying equipment is an increase of the spatial resolution and new actuators that are able to target very small areas. However, there is a lack of methods for assigning rates of herbicides relating target to optimal droplet features. A wide range of droplet impact angles occurs during the spray application process because of droplet trajectories and the variability of leaf orientation. In this study, laboratory experiments were conducted to highlight the effect of surface orientation on droplet impact outcomes (adhesion, rebound or splashing) on two very difficult-to-wet surfaces: an artificial surface with a regular roughness pattern and an excised black-grass leaf with an anisotropic roughness pattern. Measurements were performed for different surface orientations with a high-speed camera coupled with backlighting LED. Droplets of two formulations (distilled water and distilled water + a surfactant) were produced with a moving flat-fan hydraulic nozzle to obtain a wide range of droplet sizes and velocities, which were measured by image analysis. Increasing surface angle reduces surface area available for droplet capture. Droplet impact behaviors are then modified since surface tilt induces a tangential velocity component at impact and, consequently, a reduction of the normal component. Impact modifications have also been observed due to the anisotropic roughness pattern of a black-grass leaf. The integration of droplet-surface interaction information offers a significant way to further improve the precision spraying efficiency by considering the optimal droplet size, speed and ejection angle depending on the target surface and architecture. [less ▲]

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See detailUse of rotary atomiser to optimize retention on barley leaves while reducing driftable droplets
Ouled Taleb Salah, Sofiene ULg; Massinon, Mathieu ULg; Boukhalfa, Hassina dite Hafida ULg et al

in International Advances in Pesticide Application, Aspects of Applied Biology 122 (2014, January)

Controlled Droplet Application using rotary atomiser is based on an improved control of droplet size and trajectory comparatively to hydraulic nozzles. On the basis of literature, it was stated that the ... [more ▼]

Controlled Droplet Application using rotary atomiser is based on an improved control of droplet size and trajectory comparatively to hydraulic nozzles. On the basis of literature, it was stated that the use of 60° forward angled spray combined with the narrow drop size distribution of a rotary atomiser could lead to low drift and high retention on monocotyledonous and superhydrophobic weeds at early stage. A Micromax120 atomiser was tuned to emit 270 µm VMD, 60° angled forward, to increase interception by the canopy structure. A spray mixture containing a superspreader adjuvant was used to avoid drop bouncing. An increase of spray retention comparatively to a Teejet 11002 at 1.4 bars was observed, although not proved statistically significant by these preliminary trials. On the drift side, the tilted spinning disc seemed to be advantageous since droplet spectra contains a low percentage of droplets under 100 µm and presents an ejection velocity of 25 m.s-1 at 5000 RPM. The spray drift was reduced about 50%. However, these setting were not found as efficient as expected. Indeed, angled spray proved to be more sensitive to advection and turbulence, as the spray was more exposed to the airflow than for the vertical position. It appears that angling the spray and choosing a drop size spectrum with a Volume Median Diameter as big as 270 µm is not sufficient to reduce significantly this issue. Some alternatives as decreasing the emission height are possible with angled sprays but require height control that seems difficult to reach in practical situations. [less ▲]

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See detailDe l’expérimentation à la modélisation des propriétés hygrothermiques de parois isolées en paille
Louis, Arnaud ULg; Evrard, Arnaud; Courard, Luc ULg et al

in Annales du Bâtiment et des Travaux Publics (2013)

Some results of aPROpaille project are presented. The goal of this project is to improve the knowledge about hygrothermal performances of walls in which thermal insulation is mainly provided by straw ... [more ▼]

Some results of aPROpaille project are presented. The goal of this project is to improve the knowledge about hygrothermal performances of walls in which thermal insulation is mainly provided by straw. Besides an overall characterization of straw properties and two types of earth plaster, a series of tests was performed to determine the hygrothermal properties of these materials: porosity, sorption curve, water vapour diffusion, capillary absorption, total water absorption, specific heat and thermal conductivity. The determination of these parameters required sometimes the implementation of unusual protocols or unreleased materials. Numerical simulations based on the properties defined in the test campaign are also presented. Results clearly point out the influence of the type of plaster and the orientation of fibres into straw bale. [less ▲]

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See detailUse of on-line flow cytometry for the characterization of physiological behavior in stress conditions during the bioprocess
Brognaux, Alison ULg; Han, Shanshan; Soren, Sorensen et al

Poster (2013, November 15)

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See detailÉlaboration du référentiel de compétences du master bioingénieur en Sciences et Technologies de l'Environnement
Colaux-Castillo-Bocanegra, Catherine ULg; Colinet, Gilles ULg; Debouche, Charles ULg et al

in Poulin, Richard (Ed.) Séminaire CITEF 2013 La liaison formation-emploi : l'approche compétences et la formation tout au long de la vie (2013, October 18)

Le département des Sciences et Technologies de l’Environnement (STE) de Gembloux Agro-Bio Tech faculté de l’Université de Liège a profité d’un changement d’intitulé de son diplôme de bioingénieur pour ... [more ▼]

Le département des Sciences et Technologies de l’Environnement (STE) de Gembloux Agro-Bio Tech faculté de l’Université de Liège a profité d’un changement d’intitulé de son diplôme de bioingénieur pour réviser son programme des études. Pour ce faire, il a adopté l’approche compétence. Afin de préparer au mieux ses futurs diplômés aux attentes du monde professionnel actuel et à venir, des anciens diplômés et des employeurs potentiels ont participé à la validation du référentiel de compétences associé à cette formation. Cette publication reprend les étapes clés de la création du référentiel de compétences et son exploitation dans la conception d’un programme des études cohérent. [less ▲]

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See detailUse of on-line flow cytometry to detect segregation in the microbial population
Brognaux, Alison ULg; Zune, Quentin ULg; Han, Shanshan et al

Poster (2013, October 08)

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See detailDesign, Construction and Validation of a Guarded Hot Plate Apparatus for Thermal Conductivity Measurement of High Thickness Crop-Based Specimens
Dubois, Samuel ULg; Lebeau, Frédéric ULg

in Materials and Structures (2013)

The search for sustainability achievement in the building sector led to the use of crop-based insulation materials. Among these, raw products like plant straws bales can present elementary representative ... [more ▼]

The search for sustainability achievement in the building sector led to the use of crop-based insulation materials. Among these, raw products like plant straws bales can present elementary representative volumes (REVs) in the size order of several square centimeters. Fibers orientation may play an important role on material thermal behavior. Measuring their thermal conductivities with standard steady-state equipment can thus lead to some inaccuracies due to the necessity of resetting lower thickness samples. This paper presents a Guarded Hot Plate (GHP) apparatus designed to test high thickness samples, up to 40cm, with an accuracy of 2%. The different parts of the machine are described in details along with design process and challenges encountered. Temperature and heat flux measurements in the device represent critical design stages where optimal accuracy is needed in order to optimize the resulting global error. Regarding this, necessary numerical and experimental analyzes were conducted emphasizing on intrinsic systematic error assessment. To complete the study, some validations tests are performed on a reference material and other widely-spread polystyrene slabs. These tests take into account the optimal computation parameters resulting from the numerical analysis and the apparatus proved to be in accordance with accuracy requirements. [less ▲]

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See detailModeling the hygrothermal behavior of biobased construction materials
Dubois, Samuel ULg; Evrard, Arnaud; Lebeau, Frédéric ULg

in Journal of Building Physics (2013)

Materials with high moisture exchange capacity may have a strong impact on indoor climate conditions as well as building energy performance. Crop-based materials, characterized by their high porosity and ... [more ▼]

Materials with high moisture exchange capacity may have a strong impact on indoor climate conditions as well as building energy performance. Crop-based materials, characterized by their high porosity and hygroscopicity, belong to this category. Modeling their hygrothermal behavior accurately is thus particularly relevant for appropriate building design. A COMSOL Multiphysics transient heat air and moisture model is developed in this article to simulate moisture exchange between a lime–hemp concrete block and surrounding air during a Moisture Buffer Value evaluation test. Results are then compared with the validated heat air and moisture software using performance criteria showing a slight preference for both moisture exchanges and latent heat effect characterization. It offers yet additional advantages in terms of flexibility and transparency as well as further evolution potential. [less ▲]

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See detailDe l’expérimentation à la modélisation des propriétés hygrothermiques de parois isolées en paille
Louis, Arnaud ULg; Evrard, Arnaud; Biot, Benjamin et al

Conference (2013, May 31)

First results of aPROpaille project are presented. The goal of this project is to improve the knowledge about hygrothermal performances of walls in which thermal insulation is mainly provided by straw ... [more ▼]

First results of aPROpaille project are presented. The goal of this project is to improve the knowledge about hygrothermal performances of walls in which thermal insulation is mainly provided by straw. Besides an overall properties characterization of straw and two types of earth plaster, a series of tests was performed to determine the hygrothermal properties of these materials: porosity, sorption curve, water vapour diffusion, capillary absorption, total water absorption, specific heat and thermal conductivity. The determination of these parameters required sometimes the implementation of unusual protocols or unreleased materials. Numerical simulations based on the properties defined in the test campaign are also presented. Results clearly point out the influence of the type of plaster and the orientation of fibres into straw bale. [less ▲]

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See detailHygrothermal behavior modeling of different Lime-Hemp Concrete mixes
Dubois, Samuel ULg; Lebeau, Frédéric ULg

Conference (2013, May 28)

This paper studies the specific hygrothermal behavior of Lime-Hemp concretes through analysis of non-linear coupled heat and moisture transfer using a research model. Three compositions were studied ... [more ▼]

This paper studies the specific hygrothermal behavior of Lime-Hemp concretes through analysis of non-linear coupled heat and moisture transfer using a research model. Three compositions were studied, varying the type of binder. First Moisture Buffer Value determination tests are lead experimentally using the NORDTEST protocol. These dynamic experiments, which reveal the moisture storage and exchange capacity together with latent heat effects, are then modeled using a set of partial differential equations. The reduction of humidity buffering capacity induced by hydraulic binder incorporation is properly evaluated and the hygrothermal parameters can be assessed by inverse modeling. [less ▲]

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