The object of this thesis is to investigate the performance in detail and to improve the efficiency of an exterior-rotor burshless DC motor provided by a motor manufacturing company. The finite element software package FLUX3D will be adopted to conduct all the analyzing works. At first, the three-dimensional static magnetic model of the machine will be formulated by FLUX3D. After confirming the preliminary analyzing results with practical measurements, static magnetic circuit of the machine system will be established to seek the possible flux leakage paths. By adjusting the thickness of permanent magnets and the shapes of stator poles, the effectiveness of machine operational efficiency improvements as well as induced torque changes will be obtained. Finally, from these investigations, adequate suggestions for design and construct the associate machine will be provided.

Für zahlreiche technische Prozesse ist die Kenntnis des Schlupfes bzw. des Drift-Fluxes in Zweiphasenströmungen notwendig. Beispiele sind die Bestimmung der Druckverluste sowie der Wärme- und Stoffübertragungsvorgänge in Verdampfern oder Kondensatoren, der Phasenverweilzeit in chemischen Reaktoren sowie der Moderatorwirkung des zweiphasigen Kühlmittels innerhalb des Kerns eines Siedewasserreaktors.

Rapport de stage DESS : Ingénierie documentaire : Ecole nationale supérieure des sciences de l'information et des bibliothèques, Université Claude Bernard Lyon 1 : 2002.

Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xv, 211 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 200-211).

Mémoire de recherche diplôme de conservateur des bibliothèques : Bibliothéconomie : Villeurbanne, ENSSIB : 2005. / Texte intégral.

Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xx, 156 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 144-156).

No description available.

Determining sustainable water resource utilization rates is an important problem faced by regulatory agencies all around the world. One of the key parameters in determining accurate water budgeting schemes is the rate of water resource replenishment, or ‘recharge’ in groundwater systems. Fundamental questions regarding groundwater recharge include: What is the source of recharge? What is the spatial distribution of recharge? What is the annual average recharge rate, from potentially disparate sources in disparate areas? Answers to these questions can be gained through combining physical and chemical hydrogeological research tools, including stable isotopic compositions. Land-use intensification, including significant increases in dairying, has placed a priority on developing water resource management practices throughout New Zealand. Here we present the first compilation of delta oxygen-18 and delta hydrogen-2 values from individual precipitation events, local surface waters, depression springs, and groundwaters from the greater-Christchurch area. A variety of analytical methods were used in an effort to evaluate the potential use of stable isotopic compositions as tracers of surface-groundwater interaction in the local hydrologic cycle. The results of this thesis found the isotopic variability of Christchurch precipitation to be highly varied. Back-trajectory analysis of single precipitation events exhibit pathways arriving from three principal sources: the Southern Pacific Ocean, the Tasman Sea, and the Tropical Pacific Ocean. Separately, delta oxygen-18 and delta hydrogen-2 values values from these sources show three distinct local meteoric water lines, which are determined to be largely affected by the environmental conditions present in these areas at the time water vapour formation. Intra-storm variation of extra-tropical cyclones support these findings as significant changes in deuterium excess as moisture sources change with southward movement of the low pressure system. Three line-conditioned tests were subsequently developed to compare the relationship between monthly surface rainfall, surface water, and groundwater samples to the respective moisture origins. Surface rainfall, rainfall infiltration, surface waters, and groundwaters all exhibit the least amount of deviation from the Southern Pacific Ocean local meteoric water line. These observations suggest the principle moisture source to Christchurch to be from west-south westerly flow from the mid-latitudes. However, these similarities do not make partitioning their relative contributions to the groundwater system easy. Previous physical and isotopic investigations have shown the dominant sources of recharge to the Christchurch Groundwater System (CGS) are alpine rivers and local precipitation of which there is statistically significant difference with respect to delta oxygen-18 values. A binary single-isotope mixing model allows for quantification of the relative contributions of alpine river and precipitation derived inputs to local depression springs. The isotopic model indicates that approximately 80% of spring discharge was derived from alpine rivers, in good agreement with recently published physical mass balance model results. Deep groundwater flow paths however show groundwater to flow from the Central Canterbury Plains to the CGS. Potentially including losses from the upper Waimakariri River reaches. If included, this places a net recharge amount to the CGS water budget, which if using losses from only the lower Waimakariri River, there is a net loss. Losses from the upper reaches and subsequent groundwater flow into the CGS are likely as there have been no observed declines in groundwater levels even though there is currently a net loss by only using recharge components within the CGS. Ultimately, recharge from groundwater movement from the Central Canterbury Plains may play significant role; however, a much more sophisticated geochemical model is needed to test these theories and determine contributions. This research demonstrates the utility of stable isotopes as tracers of hydrogeological processes, particularly in shallow groundwater, and their potential contributions to the water resource allocation decision making process.

No description available.

Accurate knowledge of the neutron flux distribution in a nuclear reactor has many tangible benefits. Perhaps the most important are the contributions to reactor safety. Detailed knowledge allows reactor operators to identify off-normal conditions quickly before they cause serious complications. Furthermore, reactor safety margins can be accurately quantified. As advanced reactor types are proposed, new sensor systems should be developed together with new algorithms for neutron flux reconstruction. This thesis develops neutron flux reconstruction methods for in-core sensors placed in HTRs. Sensor systems developed for current generation reactors cannot be used in HTRs. The high temperatures inside HTRs preclude the use of existing in-core sensors, and complex flux phenomena arising from the inner reflector and three-dimensional fuel block arrangements suggest that new flux reconstruction methods should be developed as well. Computer simulations were run to generate detailed in- core neutron flux distributions representative of HTRs. Next, this data was used to test two different flux reconstruction algorithms. It was found that the reconstruction algorithm based on the proper orthogonal decomposition performed better than the algorithm based on linear interpolation.