Les travaux de cette thèse ont pour objectif d’étudier la machine asynchrone à cage dans le contexte d’une conversion de l’énergie éolienne dans des sites isolés. Après un bref rappel des concepts de la conversion de l’énergie éolienne en énergie électrique, ce document dresse un état de l'art des différents solutions électrotechniques utilisées tant dans le domaine de production de masse que dans celui de l’alimentation de sites isolés. Le second chapitre est dédié à la modélisation de la machine asynchrone à cage. Le modèle linéaire de la machine asynchrone présentant des limites, une modélisation originale et simple, dans laquelle le phénomène de la saturation est pris en compte par une inductance magnétisante fonction du courant magnétisant a été élaboré. Les paramètres de ce modèle peuvent être obtenus à partir d’essais ou d’une approche numérique par élément finis en 2D. Les outils de modélisation proposés sont ensuite utilisés pour l’étude des performances de la machine asynchrone dans le cas de fonctionnements en génératrice autonome débitant sur des bancs de capacités et des charges équilibrées et déséquilibrées. Les résultats de simulation sont validés expérimentalement sur un banc d’essais. La dernière partie du mémoire est consacrée à la comparaison de deux techniques de commande de la génératrice asynchrone, autonome, débitant sur un redresseur à MLI (commande vectorielle, contrôle direct du couple). Le but de ces techniques est de maintenir une tension constante à la sortie du redresseur pour des charges et des vitesses variables. Cette tension est ensuite ondulée à la bonne amplitude et fréquence pour une utilisation en site isolé. Pour chaque technique, deux stratégies ont été testées (àflux constant et à flux variable en fonction de la vitesse). Les résultats de simulation ont montrél’efficacité de ces techniques ainsi que les intérêts et les limites de chacune d’elles. / The work of this thesis aims to study the squirrel cage induction machine in the context of the wind energy conversion in isolated locations. After a brief review of the concepts of converting wind energy into electrical energy, this document describes the state of the art of different solutions used in both the mass production electrical field than in the supply of isolated sites. The secondchapter is dedicated to the modelling of squirrel cage induction machine. As the linear model presents limitations, a new and simple model, in which the saturation phenomenon is taken into account by a magnetizing inductance function of the magnetizing current, was developed. The parameters of this model can be obtained from tests or numerical approach using 2D FEM. The proposed modelling tools are then used to study the performance of stand alone induction generators connected to capacitive bank and balanced and unbalanced loads. The simulation results are validated experimentally on a test bench. The last part of the thesis is devoted to comparison of two techniques for controlling the induction generator, self-feeding a PWM rectifier (Vector Control, Direct Torque Control). The purpose of these techniques is to maintain a constant voltage at the output of the rectifier whatever the loads and speeds. This voltage is then adapted by the inverter to the good magnitude and frequency for a use in isolated areas. For each technique, two strategies were tested (at constant flux and variable flux depending on speed). The simulation results showed the effectiveness of these techniques and the interests and limitations of each.

Class of 2009 Abstract / OBJECTIVES: The purpose of this study was to expand the current knowledge regarding opinions about the consequences of DTCA, specifically in terms of their implications for pharmacy practice. We evaluated this by examining student pharmacist attitudes toward DTCA and their perception of its practical ramifications as they progressed through pharmacy coursework. We also compared attitudes of student pharmacists’ with those of practicing pharmacists’ as previously published. METHODS: Students at the University of Arizona College of Pharmacy, enrolled in their 1st, 2nd, and 3rd year of coursework, completed a questionnaire with 16 Likert-scale items soliciting levels of agreement with statements regarding DTCA. Two direct questions about overall support for DTCA and experience with patient questions regarding DTCA were included. Demographic data was also collected. RESULTS: No difference was found between groups of students with respect to attitudinal statements regarding DTCA when analyzed by ANOVA (p>0.05). Similar results were found for overall support for DTCA as analyzed by Chi-square (p>0.05). There was a statistically significant difference in overall support for DTCA between students and pharmacists when assessed by Chi-square (p<0.05). CONCLUSIONS: Pharmacists are more likely to not support DTCA, whereas student pharmacists are more likely to be uncertain of whether or not they support it. An obvious difference between these groups is practice experience, which probably increases exposure to DTCA. Though it is difficult to discern the cause of this difference in opinion, it may suggest a link between experience and attitudes toward advertising policy.

The demands for increasing the efficiency and lowering the environmental effects in iron and steelmaking industries have given rise to interests in application of direct reduction (DR) processes for production of iron by different gases. These advancements require comprehensive models for better control of the process conditions and the product properties. In the present thesis fundamental aspects in reduction of iron oxide were investigated. The experimental studies on reduction of iron oxide pellets were performed under well-controlled conditions in a setup designed for thermogravimetric investigations. The results indicated that the reaction rates by the applied procedure are higher compared to the procedure similar to conventional thermogravimetric analysis (TGA). This difference was caused by the time required for replacing the inert gas by the reaction gases. Reduction by H2-CO mixtures was accompanied by deposition of carbon and formation of cementite. The variations of cementite contents in the industrial iron ore pellets reduced isothermally for different durations, showed that cementite formation starts from the initial stages of reduction. The experimental conditions such as reaction temperature, carbon activity in the reaction gas and reaction time have a large impact on carbide content of the reduced samples. The kinetics of reduction of iron ore powder by H2 and CO gas mixtures with different compositions were studied using a commercial TGA setup. The results showed that the apparent rates of reaction vary linearly with the H2 and CO contents of the gas. Larger amount of H2 resulted in higher reaction rates. The data were employed in the developed reduction model for pellets. The model was based on the mechanism observed in the commercial iron ore pellets reduced by pure hydrogen. The microstructure of reacted pellets showed that reduction of the examined industrial samples is controlled by both chemical reaction and gaseous diffusion. The reduction model was developed by combining computations for the flow and mass transfer in the gas phase, diffusion of gases in the solid phase and chemical reaction at the reaction sites. The modelling and experimental results were in reasonably good agreement. The present model provides a good foundation for a dynamic multi-particle process model. The results highlighted the importance of considering the reduction mechanisms in different types of pellets prior to modelling. Experiments were undertaken to investigate the selective reduction of iron oxide in zinc ferrite. It was observed that gaseous reduction by hydrogen at temperatures up to 873 K is a potential method for reduction of iron oxide to metallic iron, while the zinc oxide remains in the product and losses of metallic zinc are negligible. Using this primary step in the hydrometallurgical processing of EAFD can overcome the difficulties for leaching of zinc ferrite. / <p>QC 20160823</p>

This paper discusses the direct product cancellation of digraphs. We define the exact conditions on G such that GxK=HxK implies G=H. We focus first on simple equations such as GxK_2=HxK_2 where K_2 denotes a single arc and then extend this to the more general situation, GxK = HxK. Our results are achieved by using a “factorial” operation on graphs, which is in some sense analogous to the factorial of an integer.

Despite being hailed as a green fuel, emissions from diesel engines including particulate matter (PM10 and PM 2.5) have been implicated in a range of adverse human health effects from lung and bladder cancers to premature mortality. In this study diesel engine exhaust emissions were collected from a light duty direct injection diesel engine on a standard test bed. Engine conditions of speed and load were altered to provide a set of total emission samples from over the engine's operating range. Diesel emission samples collected were fractionated on a silica column into aliphatic, aromatic, and polar groups of compounds, which were tested for their genotoxicity in the chromosome aberration assay in Chinese hamster ovary CHO-KI cells both with and without metabolic activation (rat liver S9 fraction). The aliphatic fractions did not exhibit cytotoxicity up to the maximum concentration assayed, and one emission sample (3000 rpm speed and 5 Nm load) assayed for effect on chromosome aberrations was not clastogenic (up to 600 pg/ml). The aromatic fractions of all engine emission samples assayed and of the fuel were not clastogenic, but did show high levels of cytotoxicity at relatively low doses, raising concern that any genotoxic effect was masked by the toxicity of certain chemicals within the fraction. Further fractionation, using 1 PLC, was therefore performed which separated the aromatics into various ring sizes. Assay of the ring fractions showed evidence of increasing clastogenicity with increasing ring size, with the -1+ -ring fractions of both the fuel and one emission sample clearly clastogenic when assayed with metabolic activation (evidence of the presence of indirect-acting genotoxic compounds within both samples). The final fractions to be assayed, the polar fractions, were clastogenic when assayed both with and without metabolic activation. All seven fractions from emission samples collected over a range of speed and load conditions caused highly significant increases in chromosome aberrations at concentrations as low as 20 μg/ml. An engine running for less than 30 minutes at 1000 rpm speed and 55 Nm load (urban driving conditions for a heavily laden vehicle) would emit 148 mg of polar group compounds for every litre of fuel consumed. Polar compounds have been shown to be a highly mutagenic fraction of air particulate samples, and as diesel emissions contribute up to 80 % of the particulate matter in urban air in some areas, diesel emissions and the polar compounds in particular are of real concern to human health. 3

Master of Arts / Department of Economics / Peri Da Silva / The literature concerning foreign direct investment and the spillover effects on domestic firms has developed significantly over the past two decades. This report examines the historical data on foreign direct investment flows and identifies several different types of spillover effects. Earlier studies identify potential horizontal spillovers but later studies suggest that these spillovers are insignificant. Recently, vertical spillovers, especially through backward linkages, have been identified as occurring in the host country. Studies indicate that this is happening particularly in the manufacturing sector for firms relying on inputs from the services sectors that have higher levels of foreign direct investment.

This article intends to contribute with the reflection upon the theories that link FDI with social and economical development. For this purpose, the meanings of the expression “human and economical development” will be briefly reviewed, and later it will be approached along the theories on the relation of FDI with development. The theories are used as a support in order to reach this article’s goal of pointing out the FDI impacts on labour conditions on the private security multinational G4S in Mozambique, thus examining the impacts of this sort of FDI towards the country’s human development.

Thesis advisor: Rudolph Hon / Groundwater in the Shepley's Hill Landfill (SHL) area had a high arsenic concentration for at least 20 years. This study is aimed at understanding the migration pathways of arsenic in the SHL area and postulating the possible sources and mechanisms for the mobilization of arsenic. A direct-push sampling technique (DPT) was applied in the summer of 2010 within the SHL and its downgradient area, which provided groundwater samples from various depths and locations. A long-term monitoring dataset from 1998 to 2009 was utilized as a subsidiary source for temporal analysis. Spatial distributions of arsenic and other major dissolved compositions were analyzed. Extremely high arsenic concentrations (up to ~ 15000 µg/L) were detected in the deep glacial sand deposits close to a peat layer within the SHL. Arsenic concentrations decrease dramatically in the downgradient area north of the SHL. The transport of arsenic in the SHL area is similar to that of iron. The source of arsenic is likely to been within the boundary of the SHL. The glacial sand overburden within the SHL provides enough source for the arsenic mobilization. A possible mechanism of arsenic mobilization in the SHL area is that the reductive dissolution/desorption of arsenic from iron bearing minerals under a lasting reducing environment created by decompositions of organic matter in waste and peat. / Thesis (MS) — Boston College, 2013. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

The replacement of internal combustion engines used for transportation by polymer electrolyte membrane fuel cells (PEMFCs) is one goal of the future since they are clean, quiet, energy efficient and capable of quick start-up. At present, fuel cells are receiving much attention at both fundamental research, and technology development levels, but cost is the main factor that hinders the commercialisation of PEMFCs. In order to reduce cost, a better, fundamental description of fuel cell operation than is presently available is required. The operation of PEMFCs simultaneously involves electrochemical reactions, current distribution, fluid mechanics, multicomponent multiphase mixtures, and heat transfer processes. It is important to have a comprehensive mathematical model to provide improved understanding of the interactions between various electrochemical and transport phenomena in PEMFCs in order to aid in the design and optimisation of fuel cells. This thesis describes research at developing such a comprehensive model.

Inward foreign direct investment (FDI) is believed to be a carrier of advanced knowledge to host countries, but how regional factors might impact FDI spillover effects is still uncertain. Meanwhile, regional industrial structure, i.e. specialization and diversity, has been frequently discussed in the literature, but there is no consensus about which type of industrial structure can promote regional innovation. In this thesis, the above two streams of literature are integrated and a theoretical model is proposed in which regional FDI and industrial structure are hypothesized to have direct and interactive effects on regional innovativeness. Provincial- and firm-level panel datasets (2000-2010) were compiled for empirical analyses. The results indicate that a foreign presence is beneficial for both regional and firm innovation capability while these associations are contingent on the level of industrial structure, namely the degree of specialization and diversity. A greater level of regional specialization is less likely to facilitate regional innovators to gain positive spillovers from FDI while an increase in diversity is more likely to reinforce the positive effects of foreign presence on regional innovativeness. As China has become the biggest FDI recipient country in the world in recent years and the Chinese industrial structure has been changing rapidly during the last few decades, an empirical study in the Chinese context would be ideal to examine the debate on the roles of industrial structure and FDI in promoting regional innovativeness. Overall, this research aims to advance the understanding about the moderating role of regional industrial structure in affecting the spillover effect of FDI on regional and firm innovation. The findings not only provide empirical evidence for the specialization versus diversity debate, but also highlight the essential role of contextual factors in facilitating regional innovativeness.