References of "Palm, Rodolphe"
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See detailA sorting optimization curve with quality and yield requirements
Ooms, David ULg; Palm, Rodolphe ULg; Leemans, Vincent ULg et al

in Pattern Recognition Letters (2010), 31(9), 983-990

Binary classifiers used for sorting can be compared and optimized using receiver-operating characteristic (ROC) curves which describe the trade-off between the false positive rate and true positive rate ... [more ▼]

Binary classifiers used for sorting can be compared and optimized using receiver-operating characteristic (ROC) curves which describe the trade-off between the false positive rate and true positive rate of the classifiers. This approach is well suited for the diagnosis of human diseases where individual costs of misclassification are of great concern. While it can be applied to the sorting of merchandise or other materials, the variables described by the ROC curve and its existing alternatives are less relevant for that range of applications and another approach is needed. In this paper, quality and yield factors are introduced into a sorting optimization curve (SOC) for the choice of the operating point of the classifier, associated with the prediction of output quantity and quality. Given examples are the sorting of seeds and apples with specific requirements. In both cases the operating point of the classifier is easily chosen on the SOC, while the output characteristics of the sorted product are accurately predicted. [less ▲]

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See detailValidity Limit of the Linear Regression Models for the Prediction
Akossou, A. Y. J.; Palm, Rodolphe ULg

in International Journal of Applied Mathematics & Statistics (2010), 16(M10), 38-48

Monte Carlo simulation methods was used to study the effects of the data structure on the quality of the predictions in linear multiple regression. Five hundred forty (540) data files were generated of ... [more ▼]

Monte Carlo simulation methods was used to study the effects of the data structure on the quality of the predictions in linear multiple regression. Five hundred forty (540) data files were generated of which the number of variables, R-square, the collinearity between the explanatory variables and the index of coefficient, that measures the importance of the explanatory variables in the model, were controlled. Predictions were influenced by the theoretical value of R-square, the method used to establish the model and, to a lesser extent, the collinearity between the explanatory variables. The determination of the minimal sample size which leads to predicted values better than those obtained by the mean of the dependant variable indicated that this size depends on the number of the explanatory variables, the theretical value of the R-square and the method used to establish the model. The minimal sample size increases with the models without variables selection and gradually decreases with the intensity of the selection. [less ▲]

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See detailPrevalence and sources of Campylobacter spp. contamination in free-range broiler production in the southern part of Belgium
Vandeplas, Sabrina ULg; Dubois Dauphin, Robin ULg; Palm, Rodolphe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(2), 279-288

A one year epidemiological study was carried out between February 2005 and January 2006 in the southern part of Belgium to assess the Campylobacter prevalence in free-range broiler production. Three ... [more ▼]

A one year epidemiological study was carried out between February 2005 and January 2006 in the southern part of Belgium to assess the Campylobacter prevalence in free-range broiler production. Three successive broiler flocks from six Belgian farms were investigated for the presence of Campylobacter spp. during the rearing period. Each flock was visited four times, before and after the outdoor rearing period. During each visit, samples were taken in the broiler house (litter, cecal droppings, water-lines, feed, anteroom) as well as from the outer rearing environment (open-air range). The Campylobacter detection in all samples was carried out according to the ISO 10272 standard. Identification was based on colonial morphology, microscopic examination, and biochemical tests. PCR multiplex was used for genetic confirmation. Campylobacter jejuni was the main species isolated from all contaminated samples. Overall, mixed infections C. jejuni/C. coli represented 40.6%, while C. jejuni and C. coli represented 46.9% and 12.5% of chicken samples respectively. A 100% flock contamination was observed in the 6 farms during the summer/autumn period, whereas only 66.7% and 33.3% of the flocks became Campylobacter-positive in spring and winter respectively, at the end of the rearing period. Half of contaminated flocks were infected before chickens have access to the open-air range. Environmental samples, especially the open-air range soil, were found to be Campylobacter-positive before flock infection. The other potential sources of contamination were delivery tray, anteroom floor and water-lines. Other animal productions like cattle on the farm, no applied rodent control, no cleaning and disinfection of water-lines between flocks, no detergent used for cleansing and thinning were recorded as risk factors. In conclusion, the contact with the environment, particularly the access to an open-air range, appeared to be the major way of Campylobacter contamination of chickens in free-range broiler production. [less ▲]

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See detailExtinction debt and colonization credit: When both phenomena are integrated
Piqueray, Julien ULg; Cristofoli, Sara; Bisteau, Emmanuelle et al

Conference (2010)

Calcareous grasslands are among the most species-rich ecosystems in temperate countries. These ecosystems suffered a high fragmentation process during the last century. Fragmentation can lead to the ... [more ▼]

Calcareous grasslands are among the most species-rich ecosystems in temperate countries. These ecosystems suffered a high fragmentation process during the last century. Fragmentation can lead to the creation of an extinction debt in remaining habitat patches. In our study site, it was shown in a previous study that Fragmented habitat patches (area loss since 1965 >80%) exhibited an extinction debt in comparison to Stable habitat patches (area loss since 1965 <80%). However, human activities also created new habitat patches in the landscape and provided therefore opportunities for calcareous grassland plant species to colonize new sites. They also provide opportunities for studying species colonization abilities in the context of habitat restoration. We analyzed species richness in these new patches in comparison to old patches in order to detect colonization credit. When taking as reference Fragmented patches (that exhibit an extinction debt) or all old patches (Fragmented and Stable), we concluded to the occurrence of a colonization credit in New patches. However, when the reference is Stable patches (the less likely to exhibit an extinction debt) alone, no colonization credit could be detected. Moreover, correspondence analysis revealed that New patches were similar to old patches in term of species composition. These results are encouraging for restoration programs. They also showed that the presence of an extinction debt in reference habitats can lead to mistaken conclusion in restoration monitoring. Extinction debt occurrence should be taken into account in the choice of reference habitats for evaluation of restoration success. [less ▲]

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See detailRelative efficiency of non parametric error rate estimators in multi-group linear discriminant analysis
Glele Kakaï, R. L.; Pelz, Dieter; Palm, Rodolphe ULg

in African Journal of Mathematics and Computer Science Research (2009), 2(10), 218-224

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See detailPlant species extinction debt in a biodiversity hotspot: community and species approaches
Piqueray, Julien ULg; Bisteau, Emmanuelle; Cristofoli, Sara et al

Conference (2009, April)

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See detailEmpirical Comparison Of Error Rate-Estimators In Logistic Discriminant Analysis
Glele Kakai, R; Palm, Rodolphe ULg

in Journal of Statistical Computation and Simulation (2009), 79(2),

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See detailEtude des séries chronologiques par les méthodes de décomposition
Palm, Rodolphe ULg; Brostaux, Yves ULg

in Notes de Statistique et d'Informatique (2009), (1), 1-17

This note briefly describes the main methods of analysing time series by a decomposition into a trend, a seasonal variation, and residuals. The methods are illustrated by an example analysed with Minitab ... [more ▼]

This note briefly describes the main methods of analysing time series by a decomposition into a trend, a seasonal variation, and residuals. The methods are illustrated by an example analysed with Minitab software. [less ▲]

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See detailDette d'extinction dans un hotspot de biodiversité: approches communauté et espèces
Piqueray, Julien ULg; Bisteau, Emmanuelle; Cristofoli, Sara et al

Conference (2009)

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See detailEtude dendrométrique de Pterocarpus erinaceus Poir. des formations naturelles de la zone soudanienne au Bénin
Glele Kakai, R. L.; Sinsin, B.; Palm, Rodolphe ULg

in Agronomie africaine (2008), XX(3), 245-255

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See detailMacro Minitab pour l'analyse discriminante logistique
Palm, Rodolphe ULg

Software (2008)

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See detailDétermination de la répétabilité et de la reproductibilité d'une méthode de mesure normalisée selon la norme ISO 5725-2
Palm, Rodolphe ULg

in Notes de Statistique et d'Informatique (2008), (1), 1-22

This note describes the statistical aspects related to the norm ISO 5725-2 for the estimation of repeatability and reproducibility of a standard measurement method. The procedure is then applied t a real ... [more ▼]

This note describes the statistical aspects related to the norm ISO 5725-2 for the estimation of repeatability and reproducibility of a standard measurement method. The procedure is then applied t a real world example related to the measurement of land parcel areas by remote sensing. [less ▲]

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See detailPlant species extinction debt in a biodiversity hotspot: community and species approaches
Piqueray, Julien ULg; Bisteau, Emmanuelle ULg; Cristofoli, Sara ULg et al

in Belgian Journal of Botany (2008), 141(2), 189

Destruction and fragmentation of natural and semi-natural habitats are considered as major threats for plant species richness. However, the response of plant species richness to habitat alteration is ... [more ▼]

Destruction and fragmentation of natural and semi-natural habitats are considered as major threats for plant species richness. However, the response of plant species richness to habitat alteration is sometimes delayed. This delay induces an extinction debt in plant communities that are thus prone to undergo species extinctions in the following years. Several methodologies were proposed to detect this extinction debt and estimate the mean number of species yet to disappear. In this study, we developed a new methodology for the estimation of the extinction debt extent. Moreover, we proposed a species approach aimed at determining which species are more sensitive to extinction as a consequence of habitat destruction and fragmentation. Finally, we explored the colonization ability of habitat specialist species. This aspect is of fi rst importance to counteract local species extinctions. Our model habitat is calcareous grasslands of Southeast Belgium that have suffered an important fragmentation process since the beginning of the twentieth century. We estimated that the mean extinction debt of the calcareous grassland patches was ca. 24 species, including ca. six specialist species. We showed that 16 of the 46 specialist species did not meet their area requirement anymore and were therefore considered as sensitive to extinction. However, the species composition of the more recent grasslands indicates a non-negligible recolonization potential of specialist species. There is thus a real possibility to reduce extinction risk by restoring suitable habitats. [less ▲]

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See detailData driven choice of the classification rule in discriminant analysis applied to isoberlinia stands
Glele Kakaï, R. L.; Palm, Rodolphe ULg

in West African Journal of Biophysics and Biomathematics (2007), 1

A simulation study is performed to evaluate, in discriminant analysis, the relative performance of the linear, quadratic and logistic rules, on 52,800 sample couples, characterized by the distribution and ... [more ▼]

A simulation study is performed to evaluate, in discriminant analysis, the relative performance of the linear, quadratic and logistic rules, on 52,800 sample couples, characterized by the distribution and the overlap of the populations, the number of variables, the samples size and the theoretical heteroscedasticity degree of the populations, defined in the study. For each sample couple, the relative error of the actual error rate of each classification rule is computed as well as the estimated heteroscedasticity degree and the multinormality test's statistic. The results obtained helps to notice that the linear rule can be advised when the multinormality hypothesis is accepted and the logistic rule in the other cases. The quadratic rule gives the lowest performance in most of the considered cases. Anoter method is based on the estimated heteroscedasticity and normality degrees of the considered sample couple. [less ▲]

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See detailEtude des séries chronologiques par les méthodes de lissage
Palm, Rodolphe ULg

in Notes de Statistique et d'Informatique (2007), (1), 1-22

This note briefly describes forecasting procedures for time series based on smoothing techniques. The following procedures are examined : exponential smoothing for non-seasonal time series showing no ... [more ▼]

This note briefly describes forecasting procedures for time series based on smoothing techniques. The following procedures are examined : exponential smoothing for non-seasonal time series showing no trend, Holt procedure for non-seasonal time series with trend and Holt-Winters procedure for time series containing trend and seasonal variation. The methods are illustrated by an example processed with Minitab software. [less ▲]

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