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See detailEstimation of heritability and genetic correlations for the major fatty acids in bovine milk
Soyeurt, Hélène ULg; Gillon, Alain ULg; Vanderick, Sylvie ULg et al

in Journal of Dairy Science (2007), 90(9), 4435-4442

The current cattle selection program for dairy cattle in the Walloon region of Belgium does not consider the relative content of the different fatty acids (FA) in milk. However, interest by the local ... [more ▼]

The current cattle selection program for dairy cattle in the Walloon region of Belgium does not consider the relative content of the different fatty acids (FA) in milk. However, interest by the local dairy industry in differentiated milk products is increasing. Therefore, farmers may be interested in selecting their animals based on the fat composition. The aim of this study was to evaluate the feasibility of genetic selection to improve the nutritional quality of bovine milk fat. The heritabilities and correlations among milk yield, fat, protein, and major FA contents in milk were estimated. Heritabilities for FA in milk and fat ranged from 5 to 38%. The genetic correlations estimated among FA reflected the common origin of several groups of FA. Given these results, an index including FA contents with the similar metabolic process of production in the mammary gland could be used, for example, to increase the monounsaturated and conjugated fatty acids in milk. Moreover, the genetic correlations between the percentage of fat and the content of C14:0, C12:0, C16:0, and C18:0 in fat were −0.06, 0.55, 0.60, and 0.84, respectively. This result demonstrates that an increase in fat content is not directly correlated with undesirable changes in FA profile in milk for human health. Based on the obtained genetic parameters, a future selection program to improve the FA composition of milk fat could be initiated. [less ▲]

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See detailEstimation of HIV treatment-efficacy by combining structural nested mean models with pharmacokinetic models of antiretroviral drug exposure
Comté, Laetitia ULg; Vansteelandt, Stijn; Rode, Richard et al

in Statistics and its interface (2011), 4(4), 511-520

The aim of treating HIV-1-infected patients is to achieve and maintain suppression of viral load (VL). Achievement of this aim is thwarted by variable adherence to prescribed anti-retroviral drugs ... [more ▼]

The aim of treating HIV-1-infected patients is to achieve and maintain suppression of viral load (VL). Achievement of this aim is thwarted by variable adherence to prescribed anti-retroviral drugs. Variable adherence to an antiretroviral regimen creates variability in the patient’s internal exposure to the drugs. Structural nested mean models (SNMMs) enabled us to estimate, during the initial phase of treatment, the relationship between variable internal exposure and VL, accounting for measured time-varying confounders and feedback relations using an antiretroviral regimen containing lopinavir/ritonavir (LPV/RTV, LPV/r). Our final SNMM predicts that the short term effect of treatment is modified by the most recent past VL, with higher initial VL’s being associated with larger treatment-induced reductions in VL for a given internal exposure to the drugs. Variation in internal exposure to LPV/r in the interquartile interval (P25%–P75%) only slightly affects the overall reduction in VL, supporting the conclusion that the relatively long duration of action of LPV/r lessens the impact on VL of the most frequently recurring intermittent lapses in dosing. [less ▲]

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See detailEstimation of human orientation based on silhouettes and machine learning principles
Pierard, Sébastien ULg; Van Droogenbroeck, Marc ULg

in International conference on pattern recognition applications and methods (ICPRAM) (2012, February)

Estimating the orientation of the observed person is a crucial task for home entertainment, man-machine interaction, intelligent vehicles, etc. This is possible but complex with a single camera because it ... [more ▼]

Estimating the orientation of the observed person is a crucial task for home entertainment, man-machine interaction, intelligent vehicles, etc. This is possible but complex with a single camera because it only provides one side view. To decrease the sensitivity to color and texture, we use the silhouette to infer the orientation. Under these conditions, we show that the only intrinsic limitation is to confuse the orientation q with the supplementary angle (that is 180°-theta), and that the shape descriptor must distinguish between mirrored images. In this paper, the orientation estimation is expressed and solved in the terms of a regression problem and supervised learning. In our experiments, we have tested and compared 18 shape descriptors; the best one achieves a mean error of 5:24°. However, because of the intrinsic limitation mentioned above, the range of orientations is limited to 180°. Our method is easy to implement and outperforms existing techniques. [less ▲]

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See detailEstimation of human orientation in images captured with a range camera
Pierard, Sébastien ULg; Leroy, Damien; Hansen, Jean-Frédéric et al

in Advanced Concepts for Intelligent Vision Systems (ACIVS) (2011, August)

Estimating the orientation of the observed person is a crucial task for some application fields like home entertainment, man-machine interaction, or intelligent vehicles. In this paper, we discuss the ... [more ▼]

Estimating the orientation of the observed person is a crucial task for some application fields like home entertainment, man-machine interaction, or intelligent vehicles. In this paper, we discuss the usefulness of conventional cameras for estimating the orientation, present some limitations, and show that 3D information improves the estimation performance. Technically, the orientation estimation is solved in the terms of a regression problem and supervised learning. This approach, combined to a slicing method of the 3D volume, provides mean errors as low as 9.2° or 4.3° depending on the set of considered poses. These results are consistent with those reported in the literature. However, our technique is faster and easier to implement than existing ones. [less ▲]

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See detailEstimation of hydraulic conductivity and its uncertainty from grain-size data using GLUE and artificial neural networks
Rogiers, Bart; Mallants, Dirk; Batelaan, Okke et al

in Mathematical Geosciences (2012), 44(6), 739-763

Various approaches exist to relate saturated hydraulic conductivity (Ks) to grain-size data. Most methods use a single grain-size parameter and hence omit the information encompassed by the entire grain ... [more ▼]

Various approaches exist to relate saturated hydraulic conductivity (Ks) to grain-size data. Most methods use a single grain-size parameter and hence omit the information encompassed by the entire grain-size distribution. This study compares two data-driven modelling methods, i.e.multiple linear regression and artificial neural networks, that use the entire grain-size distribution data as input for Ks prediction. Besides the predictive capacity of the methods, the uncertainty associated with the model predictions is also evaluated, since such information is important for stochastic groundwater flow and contaminant transport modelling. Artificial neural networks (ANNs) are combined with a generalized likelihood uncertainty estimation (GLUE) approach to predict Ks from grain-size data. The resulting GLUE-ANN hydraulic conductivity predictions and associated uncertainty estimates are compared with those obtained from the multiple linear regression models by a leave-one-out cross-validation. The GLUE-ANN ensemble prediction proved to be slightly better than multiple linear regression. The prediction uncertainty, however, was reduced by half an order of magnitude on average, and decreased at most by an order of magnitude. This demonstrates that the proposed method outperforms classical data-driven modelling techniques. Moreover, a comparison with methods from literature demonstrates the importance of site specific calibration. The dataset used for this purpose originates mainly from unconsolidated sandy sediments of the Neogene aquifer, northern Belgium. The proposed predictive models are developed for 173 grain-size -Ks pairs. Finally, an application with the optimized models is presented for a borehole lacking Ks data. [less ▲]

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See detailEstimation of in vivo muscle protein turnover in young bulls treated with anabolic agents
Van Eenaeme, Christian ULg; Baldwin, Paule; Lambot, Olivier et al

in Proceedings of the 4th Int. Symp. Protein metabolism and nutrition (1983)

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See detailEstimation of joint contact forces in the equine digit
Noble, Prisca ULg; Collin, Bernard ULg; Denoix, Jean-Marie et al

in ISB proceedings (2009, July)

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See detailEstimation of latent heat fluxes with a modified Jackson model applied to sparse vegetation : application to the hapex Sahel experiment
Tychon, Bernard ULg; Wollenweber, Gabriele

in Demarée, G.; Alexandre, J.; De Dapper, M. (Eds.) Proceedings of the International conference "Tropical climatology, meteorology and hydrology. In memoriam Franz Bultot" Brussels, 22-24 May, 1996 (1998)

The Jackson Model allows to estimate daily actual evaporation from the integrated daily net radiation and from the difference between surface temperature and air near-midday. Accepting a few assumptions ... [more ▼]

The Jackson Model allows to estimate daily actual evaporation from the integrated daily net radiation and from the difference between surface temperature and air near-midday. Accepting a few assumptions and after mathematical manipulations of the initial model, the daily evapotranspiration can be obtained if the near-midday instantaneous sensible heat fluxes and the daily and near midday net radiation are known. This paper focus on the estimation of the instantaneous sensible heat fluxes. Two approaches are used to estimate them : the first uses a classical approach which represents the surface with a homogeneous single layer. The second model approximates the surface with a double-layer. In the latter model, one layer represents the soil and herbaceous vegetation while the second layer is assumed to represent the foliage of trees or shrubs (high vegetation) depending on the site. Finally, this double-layer model is simplified to allow its use by remote sensors observations. These three models are compared with field measurements during the Hapex-Sahel 92 experiment in Niger. The results show that the classical one-layer model is unable to express the latent heat fluxes of this sparse vegetation while the two double-layer models appear promising and need further developments. [less ▲]

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See detailEstimation of modal correlation coefficients from background and resonant responses
Denoël, Vincent ULg

in Structural Engineering and Mechanics: an International Journal (2009), 32(6), 725-740

A new simple relation for the estimation of modal correlation coefficients is presented. It is obtained from the decomposition of covariances of modal responses into background and resonant contributions ... [more ▼]

A new simple relation for the estimation of modal correlation coefficients is presented. It is obtained from the decomposition of covariances of modal responses into background and resonant contributions, as it is commonly done for the variances. Thanks to appropriate assumptions, the modal correlation coefficients are estimated as weighted sums of two limit values, corresponding to the background and resonant responses respectively. The weighting coefficients are expressed as functions of the background-to-resonant ratios, which makes the proposed formulation convenient and easily accessible. The simplicity of the mathematical formulation facilitates the physical interpretation. It is for example proved that modal correlation coefficients can be non negligable even in case of well separated natural frequencies, which is sometimes unclear in the litterature. The new relation is mainly efficient in case of large finite element models. It is applied and validated on a finite element buffeting analysis of the Viaduct of Millau, the highest bridge deck ever built so far. [less ▲]

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See detailEstimation of Myostatin gene effects on production traits and fatty acid contents in bovine milk
Vanrobays, Marie-Laure ULg; Bastin, Catherine ULg; Colinet, Frédéric ULg et al

in Book of Abstracts of the 63rd Annual Meeting of the European Federation of Animal Science (2012, August)

Detailed reference viewed: 24 (5 ULg)
See detailEstimation of non-additive genetic variances and maternal inbreeding depression in Canadian Herefords
Duangjinda, M.; Druet, Tom ULg; Misztal, I. et al

in Abstracts from the 2000 ADSA/ASAS joint annual meeting (2000)

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See detailEstimation of odor emission rate from landfill areas using the sniffing team method
Nicolas, Jacques ULg; Craffe, Flavien; Romain, Anne-Claude ULg

in Waste Management (2006), 26(11), 1259-1269

The monitoring of the odor annoyance generated by a landfill area is difficult, since it is a multi-area-sources problem, with a discontinuous odor emission. This paper proposes an adaptation of the ... [more ▼]

The monitoring of the odor annoyance generated by a landfill area is difficult, since it is a multi-area-sources problem, with a discontinuous odor emission. This paper proposes an adaptation of the method of sniffing team campaigns to the particular case of fresh waste odors. The method is based on the field determination of odor perception points, followed by data processing with a bi-Gaussian-type model, adapted to handle the odors. In a first step, field observers delineate the region in which odor impact is experienced and then the emission rate is manipulated in a dispersion model until the predicted size of the impact zone matches that observed in the field. In a second step the adjusted emission rate is entered into the model to calculate the percentiles corresponding to the average annoyance zone. The originality of the proposed method is the introduction of all observation points and of all recorded meteorological data into the model. The paper discusses the method limitations and the errors induced on the results, i.e. the odor emission rate and the percentile lines (or iso-concentration lines) which are used to describe the odor concentrations on a map of the surroundings of the plant.The proposed method proves to be reliable for diffuse sources, such as landfill areas. The obtained results are coherent with other results found in the literature with other techniques. [less ▲]

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See detailEstimation of phenotypic and genetic parameters for weight gain and weight at fixed ages in the double-muscled Belgian Blue Beef breed using field records
Coopman, F.; Krafft, A.; Dewulf, J. et al

in Journal of Animal Breeding & Genetics (2007), 124(1), 20-25

In the double-muscled Belgian Blue beef (DM-BBB) breed, selection focuses on muscular conformation and not on weight gain and higher weight. There are very few studies on growth in the DM-BBB using field ... [more ▼]

In the double-muscled Belgian Blue beef (DM-BBB) breed, selection focuses on muscular conformation and not on weight gain and higher weight. There are very few studies on growth in the DM-BBB using field records. Therefore, farms have no available useful figures on weight at fixed ages and weight gain for the DM-BBB. This study describes and evaluates live weights of DM-BBB animals. All the data were gathered on farms in Belgium. It was found that a male DM-BBB weighs an average of 51 kg at birth, 98 kg at 3 months, 242 kg at 7 months, 430 kg at 13 months and 627 kg at 20 months. Between the age of 7 and 20 months, weight gain is more than 1200 g a day. Females weigh 47 kg at birth, 96 kg at 3 months, 189 kg at 7 months and 332 kg at 13 months. For males, estimates of heritability for weights at 7, 13 and 20 months were between 0.21 and 0.36. The heritability for weight gain between 13 and 20 months was 0.13. This demonstrates that it is possible to select for higher weights and for increased growth between 13 and 20 months. Animals having high weights at a young age (7 and 13 months) tend to have also high weight at slaughtering age (20 months; r(g) between 0.81 and 0.98), but no additional growth between 13 and 20 months (r(g) between -0.09 and 0.00). High weight at 20 months is partially due to growth between 13 and 20 months (r(g) = 0.49). [less ▲]

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See detailEstimation of renal function in anorexia nervosa
Delanaye, Pierre ULg; Radermecker, Régis ULg; Saint-Remy, Annie ULg et al

in Kidney International (2004)

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See detailEstimation of rotor angles of synchronous machines using artificial neural networks and local PMU-based quantities
Del Angel, A.; Geurts, Pierre ULg; Ernst, Damien ULg et al

in Neurocomputing (2007), 70(16-18), 2668-2678

This paper investigates a possibility for estimating rotor angles in the time frame of transient (angle) stability of electric power systems, for use in real-time. The proposed dynamic state estimation ... [more ▼]

This paper investigates a possibility for estimating rotor angles in the time frame of transient (angle) stability of electric power systems, for use in real-time. The proposed dynamic state estimation technique is based on the use of voltage and current phasors obtained from a phasor measurement unit supposed to be installed on the extra-high voltage side of the substation of a power plant, together with a multilayer perceptron trained off-line from simulations. We demonstrate that an intuitive approach to directly map phasor measurement inputs to the neural network to generator rotor angle does not offer satisfactory results. We found out that a good way to approach the angle estimation problem is to use two neural networks in order to estimate the sin(delta) and cos(delta) of the angle and recover the latter from these values by simple post-processing. Simulation results on a part of the Mexican interconnected system show that the approach could yield satisfactory accuracy for realtime monitoring and control of transient instability. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailEstimation of rubber sliding friction from asperity interaction modeling
Bui, Q. V.; Ponthot, Jean-Philippe ULg

in Wear (2002), 252(1-2), 150-160

Interaction between a soft rubber asperity and its hard counterpart is traced with the help of a finite element computation. The analysis is aimed to estimate the influence of adhesion between rubber and ... [more ▼]

Interaction between a soft rubber asperity and its hard counterpart is traced with the help of a finite element computation. The analysis is aimed to estimate the influence of adhesion between rubber and rigid surfaces and the energy losses arising from the deformation of rubber bulk to the sliding resistance. At the contact zone, interfacial bonds are formed due to adhesion and their resistance to sliding is represented by the shear strength of the contact interface. In the rubber bulk, the hysteresis loss is calculated using an appropriate model of the viscoelastic mechanical behavior of rubber for large strains. Dependence of friction on sliding speeds and temperature is hence detected. Influence of surface roughness and contact pressure on friction is also examined. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

Detailed reference viewed: 47 (0 ULg)