Performances de reproduction du poisson chat endogène du Cameroun Clarias jaensis (Boulenger, 1909) en milieu contrôlé

Les performances de reproduction de Clarias jaensis ont été évaluées entre mai et octobre 2014 à Batié (Ouest-Cameroun). A cet effet, 30 femelles de poids moyen 199, 52 ± 34,85 g ont été réparties en 5 lots comparables. Chaque lot choisi au hasard a été soumis à l’Hormone Chorionique Gonadotrophine (HCG) aux doses de 3500, 4000 et 4500 Unités Internationales (UI) / kg et aux extraits hypophysaires des mâles et des femelles. Le poids et le diamètre des ovocytes, les taux de fécondation et d’éclosion ont été évalués. Les principaux résultats ont montré que: le poids des ovocytes a été le plus élevé (p < 0, 05) avec l’extrait hypophysaire femelle (39,33±17,08g) ; le diamètre des ovocytes a été comparable entre les traitements. Le taux de fécondation a été le plus élevé pour la dose de 4000 UI / kg de HCG (87, 50 ± 12,45%) suivi de l’extrait hypophysaire femelle (85,08 ± 14,29%). Cependant aucune différence significative (p ˃ 0,05) n’a été obtenue. Le taux d’éclosion a été plus élevé avec l’extrait hypophysaire femelle (19, 38 ± 6,58%). La reproduction artificielle chez Clarias jaensis est possible avec l’hormone HCG à 4000 UI / kg ou des extraits hypophysaires femelles.© 2016 International Formulae Group. All rights reserved.Mots clés: Clarias jaensis, espèce endogène, performances de reproduction, captivité, CamerounEnglish Title:  Reproductive performances of indigenous catfish of Cameroon Clarias jaensis (Boulenger, 1909) in captivityEnglish AbstractIn order to improve local biodiversity and number of fishes in aquaculture in Cameroon, reproductive performances in captivity of Clarias jaensis have been studied between Mai and October 2014 in Batié (West Cameroon). In fact, 30 females with 199, 52 ± 34, 85 g were divided randomly into five comparable treatments. Each was submitted to a Human Chorionic Gonatropin Hormon at 3500, 4000 and 4500 Internationals Units (UI) / kg of body weight, males and female’s pituitary extracts. The main results obtained were: The oocyte weight was significantly higher (p < 0, 05) with females’ pituitary extracts (39, 33 ± 17,08g), the oocyte diameter mean was comparable within the treatments. The higher fecundity rate was obtained with the Human Chorionic Gonadotropin Hormon at 4000 UI / kg of body weight (85, 08 ± 14, 29%). However, no significant differences (p ˃ 0, 05) were found. The hatching rate was significantly higher (p < 0, 05) with the pituitary extracts of females (19, 38 ± 6, 58%). Clarias jaensis can be reproduced artificially using Human Chorionic Gonadotropin Hormon at 4000 UI / kg of body weight or female’s pituitary extracts.© 2016 International Formulae Group. All rights reserved.Keywords: Clarias jaensis, reproductive performances, indigenous species, captivity, Cameroo

Using DOProC method in reliability assessment of steel elements exposed to fatigue

Fatigue crack damage depends on a number of stress range cycles. This is a time factor in the course of reliability for the entire designed service life. Three sizes are important for the characteristics of the propagation of fatigue cracks - initial size, detectable size and acceptable size. The theoretical model of fatigue crack progression can be based on a linear fracture mechanic. Depending on location of an initial crack, the crack may propagate in structural element e.g. from the edge or from the surface. When determining the required degree of reliability, it is possible to specify the time of the first inspection of the construction which will focus on the fatigue damage. Using a conditional probability and Bayesian approach, times for subsequent inspections can be determined. For probabilistic modelling of fatigue crack progression was used the original and new probabilistic method - the Direct Optimized Probabilistic Calculation (“DOProC”), which uses a purely numerical approach without any simulation techniques or approximation approach based on optimized numerical integration

Using DOProC method in reliability assessment of steel elements exposed to fatigue

Fatigue crack damage depends on a number of stress range cycles. This is a time factor in the course of reliability for the entire designed service life. Three sizes are important for the characteristics of the propagation of fatigue cracks - initial size, detectable size and acceptable size. The theoretical model of fatigue crack progression can be based on a linear fracture mechanic. Depending on location of an initial crack, the crack may propagate in structural element e.g. from the edge or from the surface. When determining the required degree of reliability, it is possible to specify the time of the first inspection of the construction which will focus on the fatigue damage. Using a conditional probability and Bayesian approach, times for subsequent inspections can be determined. For probabilistic modelling of fatigue crack progression was used the original and new probabilistic method - the Direct Optimized Probabilistic Calculation (“DOProC”), which uses a purely numerical approach without any simulation techniques or approximation approach based on optimized numerical integration