Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 66-69). Also available via the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Aerospace Engineering, Georgia Institute of Technology, 2007. / Yeung, Pui-Kuen, Committee Member ; Lieuwen, Tim, Committee Member ; Menon, Suresh, Committee Chair ; Seitzman, Jerry, Committee Member ; Syed, Saadat, Committee Member.

Thesis (M.S.)--Florida State University, 2006. / Advisor: Mark A. Bourassa, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed June 15, 2006). Document formatted into pages; contains vii, 30 pages. Includes bibliographical references.

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xxiv, 371 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 343-367).

Thesis (M.S.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 29, 2007) Includes bibliographical references.

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Research into the mechanisms responsible for the lasting, cyclic activity at Masaya volcano can lead to a better understanding of persistently degassing volcanoes. This study is greatly enhanced by the integration of dynamic micro-gravity, deformation and gas flux measurements. The acquisition of extended temporal and spatial geophysical data will also allow for the development of robust models for the dynamics of magmatic systems. Masaya volcano, Nicaragua, is one of the most active systems in Central America, making it an excellent natural laboratory for this study. It is noted for repeated episodes of lava lake formation, strong degassing and subsequent quiescence. Ground-based geophysical measurements show two episodes of similar magnitude gravity decreases in 1993-1994 and 1997-1999, separated by a period of minor gravity increase. A major increase in S02 gas flux from 1997-1999 correlates well with the most recent episode of gravity decrease. The gravity changes are not accompanied by deformation in the summit areas and are interpreted in terms of sub-surface density changes. The persistent degassing at Masaya suggests that up to -15 krrr' of magma may have degassed over the last 150 years, only a minute fraction of which has been erupted. Furthermore, thermal flux calculations suggest that 0.5 krrr' of magma (the estimated volume of the shallow reservoir) would cool from liquidus to just above solidus temperatures in only 5 years. The high rates of degassing and cooling at open-system volcanoes such as Masaya raise questions as to the ultimate fate of this degassed and cooled magma. A number of models have been proposed to explain this, but the most likely mechanism to explain persistent activity at Masaya and other similar volcanoes is convective removal of cooled and degassed magma and subsequent recharge by volatile-rich magma from depth. Another fundamental question in modem volcanology concerns the manner in which a volcanic eruption is triggered; the intrusion of fresh magma into a reservoir is thought to be a key component. The amount by which previously ponded reservoir magma interacts with a newly intruded magma will determine the nature and rate of eruption as well as the chemistry of erupted lavas and shallow dykes. The physics of this interaction can be investigated through a conventional monitoring procedure that incorporates the Mogi model relating ground deformation (~) to changes in volume of a magma reservoir. Gravity changes (.1.g)combined with ground deformation provides information on magma reservoir mass changes. Models developed here predict how, during inflation, the observed .1.gI~ gradient will evolve as a volcano develops from a state of dormancy through unrest into a state of explosive activity.

Le Global Sourcing est aujourd'hui en pleine expansion car il offre aux entreprises une source potentielle de compétitivité dans un environnement de plus en plus concurrentiel. Néanmoins, il génère aussi une complexification des flux et une fragilisation de la Supply Chain Globale. La problématique du Global Sourcing est vaste et touche les différents niveaux de décision de l'entreprise. Pour cela nous nous sommes focalisés dans ce travail sur les aspects tactiques et opérationnels de ce domaine. Nous avons abordé ainsi diverses questions : Quels leviers d'action pour un pilotage efficace des flux en approvisionnement lointain? Comment sécuriser les approvisionnements lointains dans le contexte industriel actuel ? Les politiques classiques de pilotage de flux sont-elles suffisantes pour les approvisionnements lointains ? En collaboration avec les partenaires industriels de la Chaire Supply Chain de l'Ecole Centrale Paris, nous avons abordé différentes facettes de cette problématique. Nous nous sommes intéressés tout d'abord à la prévision comme élément nécessaire au pilotage des flux lointains et nous avons proposé une méthodologie de sélection et de mise à jour de méthodes de prévision. Les délais longs en approvisionnement lointain font que les erreurs de prévision s'amplifient, ce qui nous a amenés à étudier l'erreur prévisionnelle. Nous avons proposé dans ce sens une modélisation fine de cette erreur et de son évolution en fonction de l'horizon temporelle de la prévision. Dans la dernière étape de ce travail, nous avons utilisé cette modélisation de l'incertitude pour piloter efficacement les flux lointains. Nous avons montré sur des cas réels issus de l'entreprise PSA l'efficacité de la méthode proposée en termes de respect du niveau de service avec un niveau de stock largement inférieur aux méthodes classiques. / Global Sourcing is becoming a common practice in industrial activities since it offers companies opportunities to improve its competitiveness in an increasingly competitive business environment. At the same time, it makes the flows more complex and the supply chain more fragile. Global Sourcing thus gives rise to a wide range of issues and impacts different levels of decision making. To address such a problem, we focus on tactical and operational decision making. We attempt to answer a variety of questions: What are possible actions for flow management in global sourcing? How to secure the procurement in the current industrial context? Are classical flow management policies also efficient in global sourcing? In collaboration with the industrial partners of the Chaire Supply Chain at Ecole Centrale Paris, we consider different problems. Firstly, we are interested in demand forecasting, an essential element for flow management in global sourcing and proposed a methodology to select an appropriate forecasting method and to update it dynamically. The fact that the lead times are long in global sourcing makes the forecast less reliable and less and less reliable when the forecast horizon increases, which requires an evaluation of the forecast accuracy. We propose a detailed model of the forecast accuracy and its evolution with time horizon involved. As the last step of the work, this forecast accuracy model is applied to a real life flow management problem in global sourcing. The case study carried out based on real life data from PSA demonstrates a clear superiority of the proposed method over existing ones in terms of both service level and inventory level.