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1. Benedetti, Arnaud. Ecoulement des milieux granulaires cohésifs soumis à des vibrations : Metabolic disorders and multi-generational consequences associated with exposure to endocrine disruptors in an amphibian model : (Xenopus tropicalis).

Degree: Docteur es, Mécanique et Physique des Fluides, 2012, Aix Marseille Université

Nous nous intéressons à l'écoulement de milieux granulaires cohésifs soumis à des vibrations horizontales en vue d'une application au remplissage des moules de presse. L'effet des vibrations est analysé pour un grain ou un milieu granulaire déposé sur un plan incliné et un milieu granulaire contenu dans une conduite verticale de section constante. Pour un grain polyédrique, trois régimes sont identifiés : stick, stick-slip et slip. Un modèle basé sur le bilan des forces appliquées à un grain a permis de préciser les limites de ces trois domaines. La vitesse des grains tend vers une asymptote lorsque l'inclinaison est inférieure à 0,7 fois l'angle de frottement entre les grains et le plan. Par ailleurs, l'inertie du grain conduit à une réduction de l'amplitude de son oscillation lorsque l'accélération augmente. La comparaison modèle-expérience permet d'estimer le coefficient de frottement. Pour un milieu granulaire de faible épaisseur, nous retrouvons les mêmes tendances. Les milieux granulaires épais sont le lieu de forts cisaillements provoquant leur étalement très rapide. En conduite verticale, une compétition s'établit entre les déplacements horizontal et vertical des particules. Selon l'inertie, les vibrations appliquées pourront conduire soit à une dilatance soit à une compaction. Cette dernière provient du déplacement de la conduite et du milieu granulaire en sens opposé pendant une partie d'une période de vibration. Si le phénomène de compaction atteint le centre de la conduite, il se forme des arches qui bloquent l'écoulement. Les observations faites à l'échelle mésoscopique permettent d'interpréter les vitesses d'écoulement mesurées à l'échelle macroscopique.

With the target to improve the feeding step during the moulding process, we study the flow of cohesive granular matter submitted to vibration. Vibration effects are first analyzed on the sliding motion of a single particle on inclined plane and also on granular matter sample deposited on an inclined plane or in a vertical funnel. For a single particle, three regimes are identified: stick, stick-slip and slip regimes. A simple model based on the movement equation of one grain allows to determinate the limits between the three regimes. The grain velocity reaches asymptote when the plane inclination is below 0.7 times the friction angle between the grain and the substrate. Otherwise, when the acceleration increases, the grain inertia leads to reduce the transverse amplitude of the grain oscillation motion. The comparison between experimental and numerical results allows to estimate a value for the friction coefficient parameter. For a granular sample, we find the same tendencies. Thick granular layers are submitted to high shear, causing a fast spreading. In vertical funnel, there is a competition between vertical and horizontal motions. Depending on granular inertia, submitted vibrations could lead to dilatancy due to the shear or lead to compaction. This compaction is due to an opposite motion direction between the sample and the funnel during one…

Advisors/Committee Members: Nicolas, Maxime (thesis director), Dalloz, Blanche (thesis director), Sornay, Philippe (thesis director).

Subjects/Keywords: Matériaux granulaires; Vibration horizontale; Cohésion; Écoulement; Frottement; Cisaillement; Dilatance; Compaction; Plan incliné; Conduite verticale; Granular matter; Horizontal vibration; Cohesion; Flow; Friction; Shear; Dilatancy; Compaction; Inclined plane; Vertical funnel

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Benedetti, A. (2012). Ecoulement des milieux granulaires cohésifs soumis à des vibrations : Metabolic disorders and multi-generational consequences associated with exposure to endocrine disruptors in an amphibian model : (Xenopus tropicalis). (Doctoral Dissertation). Aix Marseille Université. Retrieved from http://www.theses.fr/2012AIXM4717

Chicago Manual of Style (16th Edition):

Benedetti, Arnaud. “Ecoulement des milieux granulaires cohésifs soumis à des vibrations : Metabolic disorders and multi-generational consequences associated with exposure to endocrine disruptors in an amphibian model : (Xenopus tropicalis).” 2012. Doctoral Dissertation, Aix Marseille Université. Accessed September 20, 2019. http://www.theses.fr/2012AIXM4717.

MLA Handbook (7th Edition):

Benedetti, Arnaud. “Ecoulement des milieux granulaires cohésifs soumis à des vibrations : Metabolic disorders and multi-generational consequences associated with exposure to endocrine disruptors in an amphibian model : (Xenopus tropicalis).” 2012. Web. 20 Sep 2019.

Vancouver:

Benedetti A. Ecoulement des milieux granulaires cohésifs soumis à des vibrations : Metabolic disorders and multi-generational consequences associated with exposure to endocrine disruptors in an amphibian model : (Xenopus tropicalis). [Internet] [Doctoral dissertation]. Aix Marseille Université 2012. [cited 2019 Sep 20]. Available from: http://www.theses.fr/2012AIXM4717.

Council of Science Editors:

Benedetti A. Ecoulement des milieux granulaires cohésifs soumis à des vibrations : Metabolic disorders and multi-generational consequences associated with exposure to endocrine disruptors in an amphibian model : (Xenopus tropicalis). [Doctoral Dissertation]. Aix Marseille Université 2012. Available from: http://www.theses.fr/2012AIXM4717

2. Mauritsson, Karl. Ecological and Edaphic Correlations of Soil Invertebrate Community Structure in Dry Upland Forests of Eastern Africa.

Degree: Bioscience, 2018, University of Skövde

Natural forests are characterised by great vegetation diversity and create habitats for a major part of Earth’s terrestrial organisms. Plantation forests, which are mainly composed of a few genera of fast-growing trees, constitute an increasing fraction of global forests, but they only partly compensate for loss of area, habitat and ecological functions in natural forests. Plantation forests established near natural forests can be expected to serve as buffers, but they seem to be relatively poor in invertebrate species and it is not clear why. This bachelor’s degree project aimed at establishing the ecological and edaphic factors that correlate with soil invertebrate diversity in dry upland forests and surrounding plantation forests in eastern Africa. Some aspects of the above-ground vegetation heterogeneity were investigated since this was assumed to influence the heterogeneity of the soil environment, which is considered as critical for soil biodiversity. The obtained knowledge may be valuable in conservation activities in East African forests, which are threatened by destruction, fragmentation and exotic species. The study area was Karura Forest, a dry upland forest in Nairobi, Kenya. Three different sites were investigated; a natural forest site characterized by the indigenous tree species Brachylaena huillensis and Croton megalocarpus, and two different plantation forest sites, characterized by the exotic species Cupressus lusitanica and Eucalyptus paniculata, respectively. For each forest type, six plots were visited. Soil invertebrates were extracted from collected soil and litter samples by sieving and Berlese-Tullgren funnels. The invertebrates were identified, and the taxonomic diversity calculated at the order level. The ecological and edaphic factors, measured or calculated for each plot, were tree species diversity, ratio of exotic tree species, vertical structure of trees, vegetation cover, vegetation density, litter quality, soil pH, soil temperature and soil moisture. One-way ANOVA was used to compare soil invertebrate diversity and other variables between different forest types. Akaike’s Information Criterion and Multiple Linear Regression were used to establish linear models with variables that could explain measured variations of the diversity. There was some evidence for higher soil invertebrate diversity in natural forests than in surrounding plantation forests. The abundance of soil invertebrates was also clearly higher in natural forests, which indicates that natural forests are more important than plantation forests for conservation of soil invertebrate populations. Soil invertebrate diversity (in terms of number of orders present) was found to be influenced by forest type and litter quality. The diversity was higher at places with high amounts of coarse litter, which here is considered as more heterogenous than fine litter. The dependence on forest type was partly a consequence of differences…

Subjects/Keywords: Natural forests; plantation forests; Brachylaena-Croton forest; Cupressus lusitanica; Eucalyptus paniculata; exotic species; biodiversity; soil invertebrates; Berlese-Tullgren funnel; vertical structure; vegetation cover; vegetation density; litter quality; edaphic factors; soil pH; soil temperature; soil moisture; ANOVA; Multiple Linear Regression; Akaike’s Information Criterion; Ecology; Ekologi

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Mauritsson, K. (2018). Ecological and Edaphic Correlations of Soil Invertebrate Community Structure in Dry Upland Forests of Eastern Africa. (Thesis). University of Skövde. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15369

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Mauritsson, Karl. “Ecological and Edaphic Correlations of Soil Invertebrate Community Structure in Dry Upland Forests of Eastern Africa.” 2018. Thesis, University of Skövde. Accessed September 20, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15369.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Mauritsson, Karl. “Ecological and Edaphic Correlations of Soil Invertebrate Community Structure in Dry Upland Forests of Eastern Africa.” 2018. Web. 20 Sep 2019.

Vancouver:

Mauritsson K. Ecological and Edaphic Correlations of Soil Invertebrate Community Structure in Dry Upland Forests of Eastern Africa. [Internet] [Thesis]. University of Skövde; 2018. [cited 2019 Sep 20]. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15369.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Mauritsson K. Ecological and Edaphic Correlations of Soil Invertebrate Community Structure in Dry Upland Forests of Eastern Africa. [Thesis]. University of Skövde; 2018. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15369

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.