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See detailAssessment and monitoring of forest-game balance: an exclosure experiment
Lehaire, François ULg; Licoppe, Alain ULg; Lejeune, Philippe ULg

Poster (2013, August)

During the last decades, populations of large ungulates have largely increased, strengthening the pressure exerted by these species on forest vegetation. Therefore, monitoring this pressure has become ... [more ▼]

During the last decades, populations of large ungulates have largely increased, strengthening the pressure exerted by these species on forest vegetation. Therefore, monitoring this pressure has become unavoidable for sustainable forest management. Such monitoring requires a rigorous approach in order to evaluate objectively the balance between game population and forestry. The use of exclosure experiment offers an interesting solution to observe the effects of game populations on forest ecosystem. When objectives expected from forest management are clearly defined, exclosure experiments can effectively be used as a monitoring tool, to allow detecting unbalanced situations, for example, herbivore pressure threatening forest regeneration. The monitoring tool combines on one side an exclosure, defined as "the real environment", fully accessible to herbivores and, on the other side an enclosure, which is the "control treatment", fenced and therefore unavailable to any large ungulates. Our main aim was to compute a set of indicators characterizing the ecological changes due to large herbivores pressure on forest ecosystems. We identified 2 categories of ecological indicators: the short-term and the medium-term indicators. Short-term indicators require only two-year of monitoring to correctly quantify herbivore pressure whereas medium-term indicators require at least 4 years of monitoring. The study site is located in Southern Belgium (Wallonia), in mixed beech and oak forests. The predominant vegetation type is the "Luzulo-Fagetum", typically found in acidophileous beech forests. The ungulate species of interest are red deer, roe deer, wild boar and mouflon. In 2006, enclosures and exclosures (4 x 4 m) were installed in 17 sites scattered in two zones with contrasted deer densities to assess indicators efficiency. Between 2006 and 2012, we performed floristic surveys and we recorded the height, density and cover of the understory vegetation of every plot. [less ▲]

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See detailAssessment and monitoring of soil quality using indices based on near infrared reflectance (NIR) spectroscopy
Cécillon, Lauric; Barthès, Bernard; Gomez, Cécile et al

in European Journal of Soil Science (2009), 60(5), 770-784

Detailed reference viewed: 28 (5 ULg)
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See detailAssessment and spatial characterization of pastoral resources in northern Morocco
Chebli, Youssef; Chentouf, Mouad; Cabaraux, Jean-François ULg

in Proceedings of the 1st FARAH Day, Faculty of Veterinary Medicine (2014)

Detailed reference viewed: 26 (5 ULg)
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See detailAssessment Demands of the Second Language Curricula of Belgium’s French-Speaking Secondary Schools
Noiroux, Kevin ULg

Conference (2014, July)

The second language curricula of Belgium’s French-speaking community demand that secondary school teachers administer two yearly summative assessments of five skills, which forces them to overlook ... [more ▼]

The second language curricula of Belgium’s French-speaking community demand that secondary school teachers administer two yearly summative assessments of five skills, which forces them to overlook formative assessments. [less ▲]

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See detailASSESSMENT LAND DEGRADATION USING OPTICAL REMOTE SENSING AND GIS IN SALOUM ESTUARY, SENEGAL
Dieng, Ndeye Maguette ULg

Conference (2012, July)

The present study aims at assessing consequences of salinization during the last three decades in this estuary with regard to land, biodiversity and water degradation. In this respect, Landsat images ... [more ▼]

The present study aims at assessing consequences of salinization during the last three decades in this estuary with regard to land, biodiversity and water degradation. In this respect, Landsat images (1984, 1992, 1999 and 2010) were used to investigate regional time series land use/land cover. These were classified into six land-use/land-cover types: water bodies, high mangrove, low mangrove, denuded and salty soils (locally called “Tan”), savannah/rainfed agriculture and forestland. Change detection analysis of land and mangrove degradation was assessed using GIS techniques. Spectral analysis indicated that from 1984 to 2010, mangroves and savannah/rainfed agriculture are converted to “tan” (denuded and salty soils). In addition, these results showed that significant changes in land-use/land-cover occur within the whole estuary system and reflecting therefore environmental degradation, such as land desertification and salinization, and vegetation degradation which reflect the advanced of salinity [less ▲]

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See detailAssessment methodology of the intradermal tuberculosis skin test performed in cattle by field practitioners
Humblet, Marie-France ULg; Walravens, K.; Salandre, O. et al

Poster (2010)

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See detailAssessment of a 3S rotary atomizer
Ouled Taleb Salah, Sofiene ULg; Massinon, Mathieu ULg; Lebeau, Frédéric ULg

Poster (2013, May 23)

Spinning disc sprayers were first introduced to control cotton pests and diseases. These atomizers were recognized for their production of a uniform droplet size spectrum than conventional nozzles. They ... [more ▼]

Spinning disc sprayers were first introduced to control cotton pests and diseases. These atomizers were recognized for their production of a uniform droplet size spectrum than conventional nozzles. They have proved to be the most successful way of delivering pesticides in the form of Controlled Droplet Application (CDA) at very low volume application. But they were almost abandoned since the years of 1990 for high and medium volume application. Their use was found inefficient in arable crops such as cereals due to the use of inappropriate application rate and problem of penetration of spray in cereal canopies. However, these spray generators may be the best solution when the spray was to be targeted to a small weed with hydrophobic leaf surface where adhesion in the impact is essential for treatment efficiency while minimizing drift and splash thanks to reduced droplet span. In this study, aiming to maximize the control of black grass in cereals, characterization of the droplet size spectra was performed to predict the trajectory droplet and estimate the number that will hit the targeted surface. So, a CDA Micromax Ltd rotary atomizer 3S was operated at different rotation speeds (2000, 3500 and 5000 rpm), flow rates and pressures. A camera X stream -3S which allows the acquisition images in PIV mode, connected to a led lightening set at double mode exposure, were placed in front of the edge of the disc on a spray bench. Images were treated through a laboratory developed Matlab code for Particle Tracking Velocimetry Sizing. Droplets speeds according to diameters were extracted. Droplets cumulative volume according to diameters was also obtained. As the flow rate rose, the volume median diameter (VMD) increased. On the other hand, the VMD decreased as the rotation speed increased. Satellites droplets were observed when the atomizer was operating at a disc speed of 2000 rpm. For each flow rate corresponding to a drop size VMD, the number of droplets/cm2 that will affect pesticide coverage was calculated. Thus, the number of droplets that will effectively adhere depend on their impact at the moment of their arrival to the surface target. [less ▲]

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See detailAssessment of a bone biopsy technique for measuring tiludronate in horses: A preliminary study
Delguste, Catherine ULg; Doucet, Michèle; Gabriel, Annick ULg et al

in Canadian Journal of Veterinary Research = Revue Canadienne de Recherche Vétérinaire (2011), 75(2), 128-133

Detailed reference viewed: 34 (15 ULg)
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See detailAssessment of a bone biopsy technique for tiludronic acid dosage in horses: a preliminary study
Delguste, Catherine ULg; Doucet, Michèle; Gabriel, Annick ULg et al

Poster (2006, September)

Introduction Tiludronic acid as a bisphosphonate has a strong affinity for bone, making difficult the assessment of its PK profile in this deep compartment on living animals. The invasive nature of sample ... [more ▼]

Introduction Tiludronic acid as a bisphosphonate has a strong affinity for bone, making difficult the assessment of its PK profile in this deep compartment on living animals. The invasive nature of sample collection remains a limiting factor. This study was carried out in order to assess a bone biopsy technique allowing the repetition of sampling over a long period of time to dose tiludronic acid in equine bone. Material and Methods Six healthy 4- to 8-year-old Standardbred geldings were treated with tiludronic acid 1 mg/kg in a saline infusion over 30 minutes. The horses were subjected to euthanasia on days 1, 43, 57, 92, 182 and 222 post-treatment, respectively. Bone samples (test samples and larger reference samples) were taken at 4 sites per side and per horse: the lateral aspect of the metacarpal bone III (MCIII) of the forelimb, the 13th rib, the tuber coxae and the cuboïd bone. Test samples were taken with a 5-mm diameter dental drill (Implanteo™, Anthogyr), while larger reference samples were taken around the drill sample sites with an osteotome. All samples were taken immediately after euthanasia. Tiludronic acid concentrations were measured by HPLC with UV detection. Results The tuber coxae was the easiest site to sample. The sample site of the MCIII was easily accessible but due to the extreme hardness of the bone, the drill sampling was technically difficult to perform. Drill samples obtained from the 13th rib were very small, and the access more limited. Finally, the access to the cuboïd bone required considerable dissection, not performable in vivo. Extraction and dosage of tiludronic acid from the MCIII was difficult for technical reasons in most cases, in drill samples as well as in reference samples, and most (96%) of the values obtained were considered unreliable. This was also true for some samples from the 13th rib and from the cuboïd bone, to a lesser extent (42% of unreliable values for both sites). Moreover, for these two sample sites, less technical problems were encountered for the extraction and dosage of tiludronic acid in drill samples than in reference samples. No extraction or dosage problem was encountered with the tuber coxae samples. The ratio of tiludronic acid concentrations in drill versus reference samples ranged from 73% to 185% (mean: 124%), 65% to 208% (mean: 118%), and 26% to 110% (mean: 62%) respectively in the tuber coxae, 13th rib and cuboïd bone. In all but one horse, the highest concentrations in tiludronic acid were found in the tuber coxae, while the lowest values tended to be in the cuboïd bone at any time post-treatment. Tiludronic acid was still found in all bone samples 7 months after treatment. Discussion As previously reported with other tools, the drill tested in this study should permit to conveniently perform bone biopsies in the equine tuber coxae. This biopsy site would be the most appropriate for repeated sampling to dose tiludronic acid over time. This would help to design appropriate PK/PD studies with tiludronic acid in horses. This study also further confirms the long persistence of tiludronic acid in equine bone. [less ▲]

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See detailAssessment of a design to monitor the influence of crop residue management on the dynamics of soil water content with ERT
Chelin, Marie ULg; Hiel, Marie-Pierre ULg; Hermans, Thomas ULg et al

Poster (2016, April 21)

Choices related to crop residue management affect the soil structure. As a consequence, they may determinethe spatio-temporal dynamics of water content and eventually the crop yields. In order to better ... [more ▼]

Choices related to crop residue management affect the soil structure. As a consequence, they may determinethe spatio-temporal dynamics of water content and eventually the crop yields. In order to better understand the influence of these strategies on hydraulic processes occurring at the plot scale, we opted for the use electrical resistivity tomography (ERT). This approach presents the advantage to limit soil disturbance but is still faced to important challenges when applied in an agricultural field context. Especially changing soil-electrode contact has to be considered, as it can lead to bad quality data, especially for setups with small electrodes and small inter-electrode distance. The objective of this study was to test the efficiency of a high-resolution 3-D field measurement design to properly assess the dynamics of soil water content. ERT measurements were conducted in a Cutanic Siltic Luvisol in Gembloux, Belgium, on two plots of 2m^2 ploughed in Oct 2014 at a depth of 25 cm and sown with maize in April 2015. The plants were removed on one of the plots in order to obtain a bare soil reference. A grid of 98 surface stainless steel electrodes was layed-out on each plot and four sticks supporting each eight stainless steel electrodes were vertically inserted into the soil up to 1.20 m to get more detailed information in depth. The experiments were performed between Jul and Oct 2015, in order to get measurements both in dry and wet periods. For surface and borehole monitoring, a dipole-dipole array configuration including in-line and cross-line measurements was adopted. Normal and reciprocal measurements were performed systematically to assess the data quality: only the datasets with a mean reciprocal error lower than 3% were considered for the data inversion. This contribution will show the first inverted results showing the complexity of experimental design and data analysis for high-resolution, timelapse ERT in field conditions. Based on these results, we will draw conclusions about a minimal data set to be obtained in our upcoming field experiments. [less ▲]

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See detailAssessment of a multiscale fatigue damage model associated with stress gradient effects
Duchene, Laurent ULg; Marmi, Abdeljalil ULg; Habraken, Anne ULg

Poster (2014, September)

The aim of this research work is to develop a finite element numerical tool able to predict accurately the fatigue life of mechanical components. These components can have complex geometries, they can be ... [more ▼]

The aim of this research work is to develop a finite element numerical tool able to predict accurately the fatigue life of mechanical components. These components can have complex geometries, they can be submitted to a complex loading, leading to a specific stress field with possible stress concentration. Additionally, the successive cycles of loading are not necessarily identical. It is expected that the numerical tool can handle these demanding constraints. In this respect, a multiaxial fatigue damage model was implemented in our home-made finite element code Lagamine. The finite element method permits to account for the actual geometry of the mechanical part and the loading for the stress computation in the whole structure. The formulation of the multiaxial fatigue model is able to capture: - The non linear damage accumulation for multiblock and variable cyclic loading, - The effect of the mean (hydrostatic) stress, - The effect of the cycles below the fatigue limit if the damage was previously initiated. Finally, the occurrence of stress concentration will significantly reduce the life time of the studied piece. However, it is well-known that the subsequent local degradation of the material will be partly compensated by an enhanced load carrying contribution of the surrounding material, favourably leading to a reduction of the crack propagation. The stress gradients computed with different techniques are incorporated in the model so as to account for such beneficial influence. The physical roots of this model depart from the mesoscopic length scale, where the damage evolution is related to the mesoscopic accumulated plastic strain. Therefore, the variables of the model are defined at both macroscopic and mesoscopic scales and a specific scale transition method was implemented, based on the well-known simplified Zarka method but used at the multiscale level. The predictive capabilities of this multiscale multiaxial model are assessed by means of comparison with the classical Lemaitre-Chaboche model (implemented in the same FE code with stress gradient effects). For both models, the material parameters were identified from SN tests on smooth specimens of Ti-6Al-4V alloy, while the predictions of the models are validated thanks to comparison with experimental tests on notched samples, with stress gradient effects. [less ▲]

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See detailassessment of acid base imbalances in horses suffering from atypical myopathy
Van Galen, Gaby ULg; Cerri, Simona ULg; Porter, Sarah et al

in proceedings AAEP 2011 (2011, November 11)

Detailed reference viewed: 65 (15 ULg)
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See detailAssessment of an anomaly detector for jet engine health monitoring
Borguet, Sébastien ULg; Léonard, Olivier ULg

in International Journal of Rotating Machinery (2011), 2011

The goal of module performance analysis is to reliably assess the health of the main components of an aircraft engine. A predictive maintenance strategy can leverage this information to increase ... [more ▼]

The goal of module performance analysis is to reliably assess the health of the main components of an aircraft engine. A predictive maintenance strategy can leverage this information to increase operability and safety as well as to reduce costs. Degradation undergone by an engine can be divided into gradual deterioration and accidental events. Kalman filters have proven very efficient at tracking progressive deterioration but are poor performers in the face of abrupt events. Adaptive estimation is considered as an appropriate solution to this deficiency. This paper reports the evaluation of the detection capability of an adaptive diagnosis tool on the basis of simulated scenarios that may be encountered during the operation of a commercial turbofan engine. The diagnosis tool combines a Kalman filter and a secondary system that monitors the residuals. This auxiliary component implements a generalised likelihood ratio test in order to detect abrupt events. [less ▲]

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See detailAssessment of asphalt concrete acoustic performance in urban streets
Paje, S.E.; Bueno, M.; Terán, F. et al

in Journal of acoustical society of america (2008), 123(3), 1439-1445

Geo-referenced close proximity rolling noise and sound absorption measurements are used for acoustical characterization of asphalt concrete surfaces in an urban environment. A close proximity noise map of ... [more ▼]

Geo-referenced close proximity rolling noise and sound absorption measurements are used for acoustical characterization of asphalt concrete surfaces in an urban environment. A close proximity noise map of streets with low speed limits is presented for a reference speed of 50 km/h. Different pavements and pavement conditions, common in urban streets, are analyzed: dense and semidense asphalt concrete, with Spanish denomination D-8 and S-12, respectively, and on the other hand, dense pavement at the end of its service life 􏰁D-8*􏰀. From the acoustics point of view, the most favorable surface, by more than 4 dB􏰁A􏰀 compared with the S-12 mix, is the smoothest surface, i.e., the D-8 mix, even though it presents a minor absorption coefficient in normal incidence. Noise levels from dense surfaces 􏰁D-8􏰀 increase significantly over time, principally due to the appearance of surface defects such as cracks and ruts. Longitudinal variability of the close proximity tire/ pavement noise emission and surface homogeneity are also analyzed. [less ▲]

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See detailAssessment of bacterial persistence in mosquitoes according to microinjection assays in Belgium
Raharimalala, Fara Nantenaina ULg; Bawin, Thomas ULg; Boukraa, Slimane ULg et al

Poster (2013, October 02)

The problems caused by the massive used of pesticides have resulted in the establishment of resistant vectors besides the destruction of the environment. Furthermore, climate change has consequently ... [more ▼]

The problems caused by the massive used of pesticides have resulted in the establishment of resistant vectors besides the destruction of the environment. Furthermore, climate change has consequently modified the comportment of disease vectors. Current research tends to look for alternative means to overcome the problem. The goal of that study was to undertaken the way there this objective. By their presence or absence, endosymbiotic microorganisms can influence vector competence and vectorial capacity. Our research aims to study the effect of the introduction of endosymbiotic bacteria in the mosquito species that could be potential vectors of disease in Belgium. Method used was the microinjection of endosymbiotic bacteria within the detected exempt mosquito species. Three genus of suspected vectors belonging to Aedes, Anopheles and Culex were microinjected at different stages of their life cycle (eggs, larvae, pupae, and adults), and survivability of mosquitoes and persistence of microorganism were determined. Results show that survival in the different stages was variable. Furthermore, persistence of endobacteria was different depending genus and stages studied [less ▲]

Detailed reference viewed: 66 (25 ULg)
Peer Reviewed
See detailAssessment of benefits of joint use of multiple medical imaging modalities: case of 3D neuroimaging
Vigneron, Lara M.; Verly, Jacques ULg

Conference (2002, June)

Detailed reference viewed: 5 (0 ULg)