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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Red Oak Acorn Production, Mass, and Gross Energy Dynamics in the Mississippi Alluvial Valley

Leach, Alan Gregory 30 April 2011 (has links)
Acorns of red oaks (Quercus spp; Subgenus Erythrobalanus) are important forage for wildlife and seed for oak regeneration. I estimated production of viable acorns by red oaks in 5 forests in the Mississippi Alluvial Valley (MAV) and 2 greentree reservoirs (GTRs) in Mississippi. Mean acorn production in the MAV was 439 kg(dry)/ha of red oak crown (CV = 29%) during autumn-winter 2009-2010 and 794 kg/ha (CV = 19%) in GTRs during autumn-winters 2008-2010. I recommend researchers sample acorn production in the MAV for ≥5 years to improve precision of estimates (i.e., CV ≤ 15%). I estimated mass and gross energy (GE) of viable red oak acorns after 90 days in unflooded and flooded hardwood bottomlands in Mississippi. Within species, mass loss of acorns was <8.4% and variation in GE ≤0.08 kcal(dry)/g. Winter decomposition of intact viable red oak acorns would have minimal effect on wildlife carrying capacity of hardwood bottomlands.
2

Méthodologie de dimensionnement sur cycle de vie d’une distribution en courant continu dans le bâtiment : applications aux câbles et convertisseurs statiques DC/DC / Sizing methodology on the entire life cycle for building DC distribution : application on wiring and DC/DC converters

Jaouen, Cédric 09 July 2012 (has links)
Avec l’apparition des systèmes PV en toiture et des véhicules électriques, le nouveau contexte énergétique au sein du bâtiment pose, sous un nouvel angle, la question de la distribution en courant continu au sein des bâtiments. Mais comment évaluer objectivement l’intérêt d’un réseau DC ? Dans un contexte où l’énergie et les impacts environnementaux prennent chaque jour plus d’importance, la quantification des performances d’un tel système selon sa seule phase d’usage ne répond pas complètement à la question son impact global. C’est pourquoi nous proposons d’aborder la question via l’éco-dimensionnement des composants constituant ce système. Pour simplifier un problème fondamentalement complexe (multi-critères), nous avons choisi d’effectuer ces dimensionnements sur la base de la minimisation de leur consommation d’énergie primaire sur l’ensemble de leur cycle de vie (pertes + énergie grise = Gross Energy Requirement GER). L’un des objectifs étant d’apporter à la fois une méthodologie mais aussi les premiers éléments qui permettront de déterminer un optimum du niveau de tension d’une distribution en courant continu dans les bâtiments. / Since the development of roof PV systems and electric vehicles, the use of DC distribution for building has to be explored. However, an objective criterion has to be used to evaluate the interest of such distribution. While energy consumption and environmental impact criteria gain in importance, the performance quantification of such system over the use phase is not sufficient to illustrate its whole impact. That’s why we propose to tackle this evaluation through the eco-sizing of distribution component. In order to simplify this complex problem, based on a multi-criterion approach, we propose to size the components based on the minimization of their primary energy consumption over their entire life cycle. The resulting Gross Energy Requirement GER includes the embodied energy and the losses during the use phase. The objectives are to propose a methodology to determine the optimal voltage level for the building DC distribution, and also to illustrate the proposed approach from case studies. This methodology is applied on wiring and DC/DC converters.

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