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See detailRTDrift, modèle permettant d’évaluer en temps réel les risques environnementaux liés à la dérive des produits phytosanitaires
Lebeau, Frédéric ULg; Massinon, Mathieu ULg; Verstraete, Arnaud et al

Conference (2011, October 17)

Un modèle, RTDrift, a été développé pour estimer la contamination causée par la dérive pour les pulvérisateurs à rampe en cours de traitement. Un pulvérisateur a été équipé de capteurs pour mesurer les ... [more ▼]

Un modèle, RTDrift, a été développé pour estimer la contamination causée par la dérive pour les pulvérisateurs à rampe en cours de traitement. Un pulvérisateur a été équipé de capteurs pour mesurer les paramètres de la dérive dont la pression de pulvérisation, les mouvements de rampe, la vitesse et direction du vent, la température et l’humidité ainsi que la géo-localisation. Pour chaque position successive des buses, un modèle de diffusionadvection gaussien avec sédimentation est utilisé pour calculer à partir de la buse le transport de chaque classe de gouttes déterminée préalablement par granulométrie laser en prenant en compte l’évaporation. Différents essais de terrain ont été réalisés où la dérive a été mesurée à différentes distances par fluorométrie sur collecteurs. La comparaison avec le modèle montre une estimation satisfaisante de la dérive sur base des mesures embarquées et offre le potentiel d’un estimateur de dérive en temps réel. Les pistes d’améliorations ultérieures sont évoquées. [less ▲]

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See detailA FEASIBILITY STUDY OF DEVELOPING DIRECT INJECTION SPRAYING TECHNOLOGY FOR SMALL SCALE FARMS
El Aissaoui, Abdellah ULg; Lebeau, Frédéric ULg; el bahir, Lhoussein et al

in SZABÓ, Istvan; MAGÓ, László; KURJÁK, Zoltán (Eds.) II. INTERNATIONAL CONFERENCE OF THE CIGR HUNGARIAN NATIONAL COMMITTEE, THE FACULTY OF MECHANICAL ENGINEERING OF THE SZENT ISTVÁN UNIVERSITY, AND THE AGRICULTURAL ENGINEERING BOARD OF THE HUNGARIAN ACADEMY OF SCIENCES (2011, October 12)

The present study focuses on designing hydraulic scheme and process control system for small direct injection sprayer equipped with five meters' boom (10 tip nozzles) based on DC electrical energy supply ... [more ▼]

The present study focuses on designing hydraulic scheme and process control system for small direct injection sprayer equipped with five meters' boom (10 tip nozzles) based on DC electrical energy supply. A numerical model was developed by using finite volume method to study dynamic of concentration change process and to optimize the hydraulic boom design required to overcome lag transport problem related to real time application. The schemes of serial and parallel boom layouts were studied to obtain minimal lag transport for chemical concentration change process. The process control system was modelled in Matlab-SimulinkTM, and a laboratory test bench was implemented with a PID (Proportional Integral Derivative) feedback control for evaluating the performance of the constant carrier flow and the variable total flow strategies. The results of the hydraulic modelling of the serial boom layout showed that 6 mm boom diameter gave a satisfying performance in term of application uniformity (up to 97%) and lag transport along nozzles (from 0.8 to 1.5 s). The prospection of parallel scheme by feeding individually nozzles gave an even reduced lag transport (2 s) along the boom (diameter of 4 mm). The modelling of constant carrier flow control strategy showed a lag time of 2.5 s for the step speed change of 0.6 to 1.2 m/s at constant pressure of 2 bars. The total flow control strategy showed the advantage of reducing lag transport from 4 to 2.3 s when speed varied from 0.6 to 1.2 m/s in accordance with operating pressure (from 1 to 3 bars). The experimental tests showed the importance of varying carrier flow rate to improve the controller dynamic in comparison to the constant carrier flow control. [less ▲]

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See detailRTDrift: a real time model for estimating spray drift from ground applications
Lebeau, Frédéric ULg; Verstraete, Arnaud ULg; Stainier, Charles ULg et al

in Computers & Electronics in Agriculture (2011), 77(2), 161-174

A spray drift model called RTDrift was developed to estimate drift caused by ground sprayer machines. The sprayer was equipped with sensors measuring operational parameters namely spray pressure, boom ... [more ▼]

A spray drift model called RTDrift was developed to estimate drift caused by ground sprayer machines. The sprayer was equipped with sensors measuring operational parameters namely spray pressure, boom height and movements, and geolocalization. Climatic parameters, including wind speed and direction, were measured using a 2-D ultrasonic anemometer mounted on the sprayer. The nozzles spray drop size spectra were characterized using Phase Doppler Interferometer measurements. At every successive boom position, a diffusion-advection Gaussian tilted plume model computed the spray drift deposits for each drop class taking into account evaporation. The contribution of a single nozzle was calculated by integration of the individual puffs with respect to time and summation of the contributions of individual drops classes. The overall drift generated by the sprayer machine was obtained adding the contributions of all the nozzles. Field trials were performed on a fallow field with water and on crops with pesticides in various wind conditions. The ground drift was measured at different drift distances using fluorometric methods. When comparing the results of the model with experimental measurements of deposits, the model produced realistic maps of drift deposits. Some further improvement is needed in the presence of large scale eddies. The model offers potential benefits for the farmer as a real time drift estimator embedded on a sprayer machine [less ▲]

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See detailDevelopment of process control system for potential use of direct injection spraying technology
Aissaoui, Abdellah; Lebeau, Frédéric ULg; el bahir, et al

in Progress in Agricultural Engineering Sciences (2011), 7(1), 33-45

Small-scale farmers face to actual difficulties of applying pesticides accurately and safely on vegetables crops. They mainly use hand operated sprayers. As an issue, a small direct injection system based ... [more ▼]

Small-scale farmers face to actual difficulties of applying pesticides accurately and safely on vegetables crops. They mainly use hand operated sprayers. As an issue, a small direct injection system based on a five meter’s parallel boom layout was designed to improve chemical application. The boom layout was optimized to obtain the same minimal time lag response for the ten nozzles. The dynamic of the system was modeled using Simulink TM as first order model with delay. Two control strategies were implemented using PID (Proportional Integral Derivative) feedback control loops to monitor tracer injection (fluorescing) proportionally to simulated forward speed (from 0.6 to 1.2 m/s) and to control the constant operating pressure (constant carrier flow strategy) or the variable operating pressure proportionally to the injected chemical amount (variable total flow strategy). Different forward speed changes were induced using steps up and down, ramps, sine waves and sweeps excitations to evaluate the control feedback. The system stability was tested for its ability to maintain the expected concentration and application rate. The results show that the time lag remains less than 3 s (dead time < 2 s, time constant < 1 s) and the system keeps stable for the maximal speed variation (ΔV) and acceleration (ā) tested (ΔV = 200%, ā = 0.48 m/s2) which induce less than 10% variation of application rate. [less ▲]

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See detailREAL-TIME MONITORING OF ENVIRONMENTAL FACTORS TO MODEL WHEAT YIELD PRODUCTION
Dumont, Benjamin ULg; Leemans, Vincent ULg; Lebeau, Frédéric ULg et al

Poster (2010, September 07)

This paper presents the results of a one year preliminary study in which a real-time monitoring system was used to feed the STICS soil crop model. The monitoring system was made of a self-organising ... [more ▼]

This paper presents the results of a one year preliminary study in which a real-time monitoring system was used to feed the STICS soil crop model. The monitoring system was made of a self-organising wireless network within which microsensors collected and stored microclimatic and environmental data. As indicated by the statistical criteria (RMSE, normalized deviation and model efficiency), the optimisation of some wheat crop parameters allows the STICS model to predict the yields with good accuracy for three different soil types and seven different nitrogen application rates. [less ▲]

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See detailA MODEL FOR WHEAT YIELD PREDICTION BASED ON REAL-TIME MONITORING OF ENVIRONMENTAL FACTORS
Dumont, Benjamin ULg; Lebeau, Frédéric ULg; Vancutsem, Françoise ULg et al

Poster (2010, July)

This paper presents the results of a one year preliminary study in which a real time monitoring system was used to feed the STICS soil crop model. As indicated by the statistical criteria (RMSE and model ... [more ▼]

This paper presents the results of a one year preliminary study in which a real time monitoring system was used to feed the STICS soil crop model. As indicated by the statistical criteria (RMSE and model efficiency), the optimization of some wheat crop parameters allows the model to predict the yields with good accuracy for different soil type and different nitrogen application rates. [less ▲]

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See detailTEST AND EVALUATION OF TWO PROCESS CONTROL STRATEGIES FOR ADAPTING DIRECT INJECTION PESTICIDE APPLICATION TO SMALL SCALE FARMS
El Aissaoui, Abdellah ULg; Lebeau, Frédéric ULg; Destain, Marie-France ULg et al

Conference (2010, January 13)

Small scale farmers, in developing and in some developed countries, are faced to actual difficulties of applying pesticides accurately and safely on vegetables crops. They mainly use hand operated ... [more ▼]

Small scale farmers, in developing and in some developed countries, are faced to actual difficulties of applying pesticides accurately and safely on vegetables crops. They mainly use hand operated sprayers. As an issue, a small direct injection system based on a five meter's parallel boom layout was designed to improve chemical application. The boom layout was optimised to obtain the same minimal lag time response for the ten nozzles. The dynamic of the system was modelled using SimulinkTM as first order model with delay. Two control strategies were implemented using PID feedback control loops to monitor tracer injection (fluorescing) proportionally to simulated forward speed (from 0.6 to 1.2 m/s) and to control the constant operating pressure (constant carrier flow strategy) or the variable operating pressure proportionally to the injected chemical amount (variable total flow strategy). Different forward speed changes were induced using steps up and down, ramps, sine waves and sweeps solicitations to evaluate the control feedback. The system stability was tested for its ability to maintain the expected concentration and application rate. The results show that the lag time remains less than 3 s (dead time < 2s , time constant < 1s) and the system keeps stable for the maximal speed variation and acceleration tested (∆V=200%, a= 0.48 m/s2) which induce less than 10% variation of application rate. [less ▲]

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See detailDroplet internal flow measurement using micro-PIV
Lebeau, Frédéric ULg; Vetrano, Maria-Rosaria; van Beeck, Jeroen et al

Poster (2009, September 25)

The micro-PIV technique represents a development of the general particle image velocimetry technique to applications in fluid mechanics phenomena at a micrometric scale. It takes advantage from the very ... [more ▼]

The micro-PIV technique represents a development of the general particle image velocimetry technique to applications in fluid mechanics phenomena at a micrometric scale. It takes advantage from the very small depth of field of long distance objectives with high magnification to carry out accurate measurements in the focusing plane. The typical configuration consists of a microscope coupled to a pulsated laser and a double exposure PIV camera. The flow is seeded using sub-micrometric fluorescent particles. The laser light is directed on the investigated flow through the epifluorescent microscope objective. The light re-emitted by the fluorescent particles is detected by the PIV camera equipped of an optical filter to select only the fluorescence wavelength. The micro-PIV technique presents a large interest in the validation of numerical codes developed in different micro-fluidic framework such as biological flows and in industrial application as the ink-jet print-head. To investigate the micro-PIV measurements capabilities for fast moving and deforming droplets, measurement of the flow inside a jet ejected by a piezo-driven capillary up to the droplet formation by Rayleigh instability are studied in combination with PTV in order to distinguish the main liquid movement from the bulk one. Liquids differing from each other for their viscosity and their surface tension as well as piezo-element frequency in the 1 to 8 KHz range are investigated. The flow rate of the jet is adjusted by means of a pushing syringe system. Low concentration of 0.86 microns fluorescent particles is employed as seeding in order to have good signal to noise ratios. The ensemble averaging method is used to increase the height of the correlation peaks. Stroboscopic method is used to achieve several couples of frames taken in the same conditions thanks to high repeatability of piezo-driven instabilities. Moreover changing the delay of stroboscopy all the droplet formation phases can be analyzed in detail. In the experimental configuration, optical aberrations play a role since they affect the position and shape of the particle images and as a consequence the velocity field. The two main optical aberration experienced are astigmatism and measurement plane deformation. Astigmatism cannot be avoided in the experimental configuration, as it is clearly observed on droplet images were particles above and bellow the focalisation plane appear as perpendicular lines (Fig 1a). Nevertheless cross correlation method is not sensitive on particle image shape. As the measurement plane defined by the focal plane of the microscope is located inside a curved transparent object, it deformed as it was passing through a lens. The deformation of the objective plane affects the measurements as a function of the optical configuration, droplet curvature and relative refractive index. However, in the studied configuration, deformed plane differs only from the straight one of about 8 µm. The micro-PIV method is therefore suited to measure the instantaneous vector field inside droplets through cross-correlation methods (Fig 1b). The internal flow recirculation is observed. Measurements can be also performed in different planes inside the droplet depending on focalisation plane. [less ▲]

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See detailApplying control volume finite element for modelling direct injection boom spraying flow
El Aissaoui, Abdellah; Lebeau, Frédéric ULg; Destain, Marie-France ULg et al

Conference (2009, June 23)

Assessment of injection lag transport and uniformity of direct injection boom sprayer is an important issue for successful variable rate spraying technology. To estimate the boom lag transport and ... [more ▼]

Assessment of injection lag transport and uniformity of direct injection boom sprayer is an important issue for successful variable rate spraying technology. To estimate the boom lag transport and pressure loss, a numerical model is formulated on the basis of fluid hydrodynamic conservation equations. The software is implemented in visual basic. To solve the pressure – velocities equations, control volume finite element method (CV) is used to delimit elementary volumes of the boom. Linearization of the conservation laws is ensured by considering discrete form of the equations and calculating velocity and pressure step by step throughout the whole boom. The flow behaviour is simulated into a boom section divided into N elementary volumes, each of them including one nozzle. To test the model, three boom diameters (5, 6 and 8 mm) and two chemical viscosities (10-6 and 10-5 m2/s) were used. Experimental trials are carried out on boom having 2.5 m length (5 nozzles) for measuring pressure gradient and lag transport. Results showed that the model can predict the pressure losses and the lag transport accurately (error within 5%) to optimize boom designs. [less ▲]

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See detailEvaluation of realtime spray drift using RTDrift Gaussian advection-diffusion model
Lebeau, Frédéric ULg; Verstraete, Arnaud ULg; Schiffers, Bruno ULg et al

in Spanoghe, Pieter (Ed.) COMMUNICATIONS IN AGRICULTURAL AND APPLIED BIOLOGICAL SCIENCES (2009, May 19)

A spray drift model was developed to deliver real time information to the pesticide applicator. The sprayer is equipped with sensors to deliver real time measurement of operational parameters as spray ... [more ▼]

A spray drift model was developed to deliver real time information to the pesticide applicator. The sprayer is equipped with sensors to deliver real time measurement of operational parameters as spray pressure, boom height, horizontal boom movements and geolocalization. The spray droplet size spectrum as a function of pressure was characterized using PDI measurements. Wind speed and direction were measured using a sprayer mounted 2-D ultrasonic anemometer. For each successive boom position, a diffusion-advection Gaussian tilting plume model is used to compute the spray drift deposits downwind. Drift is computed independently for each droplet classes and each nozzle based on the operating parameters. Field trials were performed on a test plot in various wind conditions. The ground drift was measured for different drift distances using fluorimetry analysis. Results show that drift deposits are mainly affected by wind speed and direction what was correctly accounted for by the model. Short distance drift deposits values were overestimated by the model while long distance drift was underestimated. It appears that this most probably origins from embarked wind speed measurements and diffusion parameter. It is concluded that a treatment of embarked wind speed and diffusion measurement should be used to minimize these errors. [less ▲]

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See detailImproving in-row weed detection in multispectral stereoscopic images
Piron, Alexis ULg; Leemans, Vincent ULg; Lebeau, Frédéric ULg et al

in Computers & Electronics in Agriculture (2009), 69

Previous research has shown that plant height and spectral reflectance are relevant features to classify crop and weeds in organic carrots: classification based on height gave a classification accuracy ... [more ▼]

Previous research has shown that plant height and spectral reflectance are relevant features to classify crop and weeds in organic carrots: classification based on height gave a classification accuracy (CA) of up to 83% while classification based on a combination of three multispectral bands gave a CA of 72%. The first goal of this study was to examine the simultaneous use of both height and multispectral parameters. It was found that classification rate was only slightly improved when using a feature set comprising both height and multispectral data (2%). The second goal of this study was to improve the detection method based on plant height by setting an automatic threshold between crop and weeds heights, in their early growth stage. This threshold was based on crop row determination and peak detection in plant height probability density function, corresponding to the homogeneous crop population. Using this method, the CA was 82% while the CA obtained with optimal plant height limits is only slightly higher at 86%. [less ▲]

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See detailEffect of surfactants and biomass on the gas/liquid mass transfer in an aqueous-silicone oil two-phase partitioning bioreactor using Rhodococcus erythropolis T902.1 to remove VOCs from gaseous effluents
Aldric, Jean-Marc ULg; Gillet, Sébastien ULg; Delvigne, Frank ULg et al

in Journal of Chemical Technology & Biotechnology (2009), 84

BACKGROUND: The two-phase partitioning bioreactor (TPPB) has become a new strategy in the context of waste gas treatment. However, the impact of biomass and surfactants on gas/liquid (G/L) mass transfer ... [more ▼]

BACKGROUND: The two-phase partitioning bioreactor (TPPB) has become a new strategy in the context of waste gas treatment. However, the impact of biomass and surfactants on gas/liquid (G/L) mass transfer needs to be better evaluated because the impact of these factors on the mass transfer coefficient “ ” and the interfacial area “ ”, respectively, remains misunderstood. RESULTS: Our study showed that, firstly, the surfactant extract produced by Rhodococcus erythropolis reduced the surface hydrophobicity of the biomass. Secondly, an optimal concentration appeared to exist for both of the components, respectively 0.5 g.L-1 and 0.7 g.L-1 for biomass (B) and surfactant extract (SE) when the global mass transfer coefficient ( ) of oxygen was measured in a silicone oil/water TPPB. However, the combination of B and SE was found to induce a negative synergism. In particular, SE improved the interfacial area “ ” by increasing the bubble diameter, while B reduced it as soon as a concentration of 1g.L-1 was exceeded. By contrast, the SE acted negatively on the , while B improved it overall. CONCLUSION: Better consideration is needed of the effect of biotic components in order to understand the phenomenon of G/L mass transfer in a TPPB. The behaviour of biomass growth and surfactants may strongly influence the mathematical models suggested in the literature. [less ▲]

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See detailEfficacité de la technique d’induction florale d’Ananas comosus (L.) Merr. au moyen de charbon actif enrichi à l’éthylène (TIFBio)
Lebeau, Frédéric ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2009), 3

Pineapple is an important export crop for tropical countries. The flower induction treatments are essential to the pineapple production for economical and social reasons. For conventional agriculture ... [more ▼]

Pineapple is an important export crop for tropical countries. The flower induction treatments are essential to the pineapple production for economical and social reasons. For conventional agriculture, many chemicals are available but for organic farming ethylene is the only allowed product. A new flower induction method suited to small organic growers has been developed by the Pesticides Initiative Programme of the Coleacp funded by the European Development Fund. The trials conducted proved that the method reaches more than 80% efficiency at 10 weeks for the different application methods evaluated. The wet application trials show a doses response effect as well as effect of the application replication at 2 days interval. The flowering rate culminates at 100% after 8 weeks for the best results, obtained with the wet treatment at 250 mg per plant applied two times at 2 days interval. The different dry treatments tested gave all 85 – 90% flowering rates at 10 weeks, suggesting the presence of an undetermined limitation factor in the conditions prevailing for the trial. The time of application during the day shows no significant effect. It is concluded that the growers can use the TIFBio technique for production control. It is recommended to evaluate the most suited application technique according to their particular case as environmental effect can affect the efficiency. [less ▲]

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See detailApplications de la micro - PIV dans des écoulements libre et confiné
Vetrano, Maria-Rosaria; Ruwet, Vincent; Lebeau, Frédéric ULg et al

Conference (2008, September 16)

L’objectif de cette communication est l’étude de deux micro-écoulements différents au moyen d’un système de micro-PIV non inversé. Ces écoulements diffèrent entre eux par les aspects suivants: Le premier ... [more ▼]

L’objectif de cette communication est l’étude de deux micro-écoulements différents au moyen d’un système de micro-PIV non inversé. Ces écoulements diffèrent entre eux par les aspects suivants: Le premier, un écoulement pulmonaire, est représentatif d’un flux stationnaire confiné. Le second, la formation de gouttelettes par un capillaire contrôlé par un cristal piézoélectrique, est représentatif d’un écoulement périodique à surface libre. La faisabilité de ce type de mesure est évaluée en mettant l’accent sur le fait que ces expérimentations ont été menées sur des micro-écoulements courbes tridimensionnels. [less ▲]

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See detailCorrelation law for SMD in high viscous liquids
Vetrano, Maria-Rosaria; Lebeau, Frédéric ULg; Rambaud, Patrick et al

Conference (2008, September)

Spray characterization, i. e. a velocity map of the liquid and gaseous phases and the sizing of the liquid droplet, remains of a great importance in different industrial applications such as in the ... [more ▼]

Spray characterization, i. e. a velocity map of the liquid and gaseous phases and the sizing of the liquid droplet, remains of a great importance in different industrial applications such as in the automotive or pharmaceutical industries. Correlations capable to faster this characterization already exist. They allow the evaluation of the droplet Sauter Mean Diameter in a precise location of the spray using non-dimensional numbers involving physical and chemical properties of the liquid and the spray operative conditions. This paper concerns the possibility to include in the correlative laws also the effect of the liquid viscosity through the introduction of the Ohnesorge number (Oh). In order to achieve this goal an extensively experimentalcampaign is performed, by means of a Phase Doppler Interferometer, for size and velocity measurements in a full cone spray. Parameters as the hydraulic diameter of the nozzle, the operatingpressure and the liquid viscosity are varied in order to cover large range of Weber and Ohnesorge numbers. [less ▲]

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See detailSelection of the most efficient wavelength bands for discriminating weeds from crop
Piron, Alexis ULg; Leemans, Vincent ULg; Kleynen, O. et al

in Computers & Electronics in Agriculture (2008), 62(2), 141-148

The aim of this study was to select the best combination of filters for detecting various weed species located within carrot rows. In-field images were taken under artificial lighting with a multispectral ... [more ▼]

The aim of this study was to select the best combination of filters for detecting various weed species located within carrot rows. In-field images were taken under artificial lighting with a multispectral device consisting of a black and white camera coupled with a rotating wheel holding 22 interference filters in the VIS-NIR domain. Measurements were performed over a period of 19 days, starting 1 week after crop emergence (early weeding can increase yields) and seven different weeds species were considered. The selection of the best filter combination was based on a quadratic discriminant analysis. The best combination of filters included three interference filters, respectively centred on 450, 550 and 700 nm. With this combination, the overall classification accuracy (CA) was 72%. When using only two filters, a slight degradation of the CA was noticed. When the classification results were reported on field images, a systematic misclassification of carrot cotyledons appears. Better results were obtained with a more advanced growth stage. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailSeed rain pattern of the invasive weed Senecio inaequidens (Asteraceae)
Monty, Arnaud ULg; Stainier, Charles; Lebeau, Frédéric ULg et al

in Belgian Journal of Botany (2008), 141(1), 51-63

Dispersion capacity of alien invasive plants is a key feature for understanding invasion processes and risks. Here, we present an experimental study focussing on the seed rain pattern of Senecio ... [more ▼]

Dispersion capacity of alien invasive plants is a key feature for understanding invasion processes and risks. Here, we present an experimental study focussing on the seed rain pattern of Senecio inaequidens, an African plant widespread throughout Europe, under common favourable dispersal conditions. One hundred achenes from two Belgian populations underwent a drop time in still air experiment in order to assess linear correlation between several morphological traits and terminal velocity. Variation in morphological traits was measured for 250 additional achenes per population. The trait best correlated to terminal velocity was the square root of the plume loading. We then used this trait to model terminal velocity using a linear regression (r(2) of 79.7%). With this regression and imposing ecological parameters such as wind speed, turbulences and height of release to be representative of favourable dispersal conditions, we established a Gaussian tilted plume model to predict the seed rain pattern of the species. A wind tunnel experiment consequently permitted to validate the model. Under a wind speed of 5 m s(-1) with 2% turbulences along the vertical axis, and height of release of 0.40 m, 99.8% of achenes were dispersed within 100 meters, with a maximum deposition rate at 5.2 m from the parent plant. Uplifted achenes, not forecasted by the model, represent 6.25% of all achenes. [less ▲]

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See detailÉtude des paramètres opératoires de pressage mécanique des amandes de Vitellaria paradoxa Gaertn C.F. (karité)
Yé, S.; Lebeau, Frédéric ULg; Wathelet, Jean-Paul ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2007), 11(4), 267-273

Study of the operational parameters of mechanical pressing of almonds of Vitellaria paradoxa Gaertn C.F. (shea tree). Sheabutter is one of the most diffi cult oleaginous resources to extract by ... [more ▼]

Study of the operational parameters of mechanical pressing of almonds of Vitellaria paradoxa Gaertn C.F. (shea tree). Sheabutter is one of the most diffi cult oleaginous resources to extract by traditional way. In Burkina Faso, where production of sheanuts is estimated at 70 000 tons per year, presses manufactured locally are used to improve the production. In order to optimize the handcraft process of sheabutter production, extraction parameters of Vitellaria paradoxa Gaertn C.F. were studied under laboratory controlled conditions on 3 g samples of ground almonds using a uni-axial compression test machine specifi cally instrumented for this purpose. The studied operational parameters were the grinding (unsieved sample 0.5 mm<Ø<5 mm ; sieved samples 0.5 mm<Ø<1 mm ; 1 mm<Ø<2 mm ; 2 mm<Ø<4 mm ; 4 mm<Ø<5 mm), the heating temperature (30; 50; 70; 90; 110; 130; 150°C) and the extraction pressure (7; 10; 13.4; 15; 16.17; 17.44; 20; 22.43 and 25 MPa). The grinding has favourably infl uenced the extraction rate. The fi nest sieved fraction (0.5 mm<Ø<1 mm) presented the highest extraction rate, 84%. When using unsieved samples, the best results were obtained with a heating temperature of 90°C and an extraction pressure of 20 MPa. In these conditions, the extraction rate reached 78% and the chemical characteristics of the sheabutter were not altered. As a result, a signifi cant increase of the handcrafted presses effi ciency could be reached by simple and inexpensive modifi cations as an increase of the pressure applied to the product, by a decrease of the pressing chamber diameter. [less ▲]

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See detailModelling spray drift using a modified air pollution Gaussian tilting plume model
Stainier, Charles; Destain, Marie-France ULg; Schiffers, Bruno ULg et al

Poster (2007)

The objective of this research is to evaluate a Gaussian tilting plume model that takes into account the spray characteristics of agricultural nozzles to predict drift. The application of this type of ... [more ▼]

The objective of this research is to evaluate a Gaussian tilting plume model that takes into account the spray characteristics of agricultural nozzles to predict drift. The application of this type of model has proved to be effective for aerial pollution applications. To be applied successfully to the spray drift, the model has to give accurate predictions of the deposits regarding the spray and material characteristics as well as the weather parameters. To reach this objective, the model parameters must be correctly set based on appropriate theoretical basis and experimental data. Based on wind tunnel measurements, the effect of the most important characteristics of spray droplets from an agricultural nozzle has been modelled using a Gaussian tilting plume approach by discretizing the different droplet classes. Although the theoretical basis of the model is simple, the predicted drift appeared to be in relatively good agreement with the experimental results. The discrepancies could be explained by poor fitting of the dispersion model parameters. Further work is required to optimise the value of the model parameters. [less ▲]

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See detailWind tunnel protocol for spray drift assessment
stainier, Charles; Lebeau, Frédéric ULg; Destain, Marie-France ULg et al

Conference (2006, April 11)

The objective of wind tunnel protocol is to measure spray drift in a reproducible way in order to evaluate the relative drift potential

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