This thesis proposes one comparison methodology for single and three-phase high power high frequency transformers in power conversion systems. The objective is to compare the volume of the transformers. And single and three-phase Dual Active Bridge Converter (DAB1 and DAB3) topologies with single and three-phase isolating transformers are selected for the transformer comparison. Design optimization of power transformer has been studied and simplified models have been built for the single and three-phase transformer design optimization in this work, including assumptions for core shapes, materials, winding structures and thermal model. Two design methods have been proposed according to different design constraints, named T – B Method and J – B Method separately. T – B Method is based on feature of the core, which has the major limits of maximum flux density and temperature rise. The flux density should not reach the saturation value of the core, and temperature rise should meet specifications in different applications to assure the performance of the core (permeability, saturation flux density, and core loss) and the insulation of the wire. And J – B Method starts from the comparison of area product in conventional design method. The relationship between area product of transformer cores and the flux and current of the transformer in design is analyzed. There is specified relationship between area product of single and three-phase transformers if flux and current densities are specified for both. Thus J – B Method is proposed with the design constraints of specified current and flux density. Both design methods include both single and three-phase transformer design. One example case for single and three-phase transformer comparison is selected as high power high frequency DAB conversion system. Operation principles are studied for both DAB1 and DAB3 based on previous work. And transformer design based on the T – B and J – B Methods are carried out and transformer volumes are compared. And results show that three-phase transformer has little benefit in volume or thermal than single-phase transformer, when they are utilized in single-phase DAB and three-phase DAB converters separately. Scaled-down single and three-phase DAB systems have been built and volume and thermal tests have been carried out. / Master of Science

A Finite Element model was built to analyze and examine a 2-D axisymmetric MR damper. This model has been validated with the experimental data. The results obtained in this thesis will help designers to create more efficient and reliable MR dampers. We can create some design analysis to change the shape of the piston in the damper or other parameters in the model. The main benefit of this research is to show a 2-D MR damper and generate the magnetic flux density along the MR Fluid gap. We can detect saturation by looking at the nodal solution for the magnetic flux density. Increasing the current in the model, results in an increase in magnetic induction. We studied four different configurations of an MR damper piston in order to determine how changing the shape of the piston affects the maximum force that the damper can provide. In designing MR dampers, the designer always faces the challenge of providing the largest forces in the most compact and efficient envelope. Therefore, it is important to identify the configuration that gives more force in less space. In chapter 4, shows the magnetic flux density contour before and after reaching the rheological saturation. By increasing the current, the color spectrum of the magnetic flux density will shift from the MR fluid gap to the piston centerline. In chapter 5, we provided a reasonably good amount of force in model 4 at 1.4 Amps, but it reaches saturation before the other models. For cases with power constraint or heat build up limitations, this model could work the best among the four designs that we considered. For cases where higher electrical currents can be tolerated, model 3 would be the most advantageous design, since it provides the largest force among the four models. / Master of Science

La connaissance de l’énergie transférée aux surfaces en contact avec un plasma basse pression est un paramètre clé pour le contrôle des procédés plasmas basse pression. Sa détermination permet une meilleure compréhension des mécanismes mis en jeu lors du dépôt ou la gravure de couches couches minces. Elle dépend des espèces du plasma (les ions, les électrons et les neutres) ainsi que de nombreux mécanismes physiques ou chimiques (réaction, condensation, émission radiative.). Elle peut être déterminée par la simulation du transport des particules dans le plasma, par des estimations de chaque contribution à partir des paramètres plasma ou tout simplement mesurée. Les études dédiées à sa mesure sont principalement basées sur l’utilisation d’une sonde calorimétrique, dont le principe sur l’interpolation du thermogramme mesuré. Ce type de méthode induit un long temps de mesure (2 min) et est source d’incertitudes. Un outil de diagnostic pour la mesure directe de l’énergie transférée a été développé au GREMI. Il est basé sur l’adaptation d’un capteur à thermopile initialement dédié à des mesures à pression atmosphérique. Cette thèse a donc été dédié à son développement et son utilisation pour l’étude de différents procédés plasmas basse pression : un propulseur spatial à effet Hall, un plasma poudreux, mais surtout de décharges magnétron. Des mesures ont été réalisées lors du dépôt de titane, d’aluminium, de TiO2 et de Al2O3. Les influences de la configuration magnétique de la cathode, du type de décharge, de l’échauffement des cibles, sur les conditions énergétiques à la surface du film en croissance ont été étudiées. / The knowledge of the energy flux during plasma/surface interactions is a key parameter for the control of low pressure plasmas, as sputter deposition or etching processes. The energy flux density at a surface depends on plasma species (ions, electrons, neutrals...) elementary processes (condensation, chemical reaction, radiative transfer). It can be obtained by carring out simulation of particule transport through the plasma, by the calculation of each energetic contribution from plasma parameters or by indirect or direct measurement. Most os works focused on the mesurement of the energy flux is based on the using of a calorimetric probe. This method is based on the calculation of the temporal temperature evolution. The main disadvantages are that this methods can cause error of about 10 % and the acquisition time of the thermogram which is about 2 min. A diagnostic tool which provide a direct measurement of the energy flux, with a good sensitivity and a good time resolution was designed in the GREMI.The aim of this PhD thesis was to developped this tool and use for the study of different plasma processes as capacitiv RF discharge, Hall effect plasma thruster and especially magnetron sputter deposition process. In this last process, the influence of the cathode magnetic configuration, the reactive gas, the dicharge type (HiPIMS, DCMS and pDCMS), the heating of the target was studied on the energy flux at the growing thin film duting the sputtering of a titanium and an aluminum target.

Previous studies indicate that the degree of UV-Binduced photosynthetic inhibition may be highly dependent upon the photosynthetic photon flux density (PPFD, total quantum flux in the waveband 400-700 nm) incident on a plant. This study illustrates that Essex soybean leaves (Glycine max) preconditioned under high PPFD suffered less UV-B-induced photoinhibition than when preconditioned under low PPFD. However, sensitivity to UV-B increased when soybean leaves received high-PPFD as a concomitant treatment. The relative msgnitude of UV-B-induced damage was similar for both light-limited and light-saturated photosynthesis. This probably indicates that UV-B is inhibiting fundamentally different photosynthetic processes. Soybean leaves preconditioned under high PPFD had greater specific-leaf-weight, chlorophyll a/b ratio, and crude flavonoid content. The total chlorophyll concentration of soybean leaves preconditioned under high PPFD increased slightly over a UV-B irradiation period of five hours. Total chlorophyll concentration of leaves preconditioned under low PPFD decreased slightly in response to the same irradiation period.

This thesis deals with the integral motor of tomorrow, and particularly with a variable speed, sensorless permanent magnet synchronous motor with an integrated converter. The rated power is 15 kW at 1500 r/min. The outer dimensions are approximately the same as for the equivalent standard induction motor. Control strategies for pumps and fans, i.e. suitable loads for variable speed motors, are briefly described. The huge energy savings that can be made by reducing the speed instead of throttling/choking the flow are pointed out. Compared to installing an induction motor with a separate converter, a PM integral motor will probably pay-off in less than a year. A totally analytical expression for calculating the airgap flux density of permanent magnet motors with buried magnets is derived. The analytical expression includes axial leakage, and iron saturation of the most narrow part of the magnetic circuit of the machine. A computer program for optimization of PM motors with buried magnets has been developed. It was used to design the manufactured prototype PM integral motor, and the parameters are investigated with analytical and/or FEM calculations. The optimization program is also used to suggest nearoptimum pole numbers for desired powers (4-37 kW) and speeds (750- 3000 r/min) of inverter-fed PM motors. Results show that compact buried PM motors should have relatively large airgaps and high NdFeB-magnet masses to improve the efficiency. Ferrite magnets are unsuitable. Measurements on the manufactured PM motor, the novel concept of stator integrated filter coils, and the complete PM integral motor are presented. Special attention was given to temperature and overall efficiency measurements. The rotor cage losses were investigated by time-stepping FEM. Four short circuit fault conditions were also examined in order to evaluate the risks of demagnetization of the buried magnets.

<p>This thesis deals with the integral motor of tomorrow, and particularly with a variable speed, sensorless permanent magnet synchronous motor with an integrated converter. The rated power is 15 kW at 1500 r/min. The outer dimensions are approximately the same as for the equivalent standard induction motor.</p><p>Control strategies for pumps and fans, i.e. suitable loads for variable speed motors, are briefly described. The huge energy savings that can be made by reducing the speed instead of throttling/choking the flow are pointed out. Compared to installing an induction motor with a separate converter, a PM integral motor will probably pay-off in less than a year.</p><p>A <i>totally analytical</i> expression for calculating the airgap flux density of permanent magnet motors with buried magnets is derived. The analytical expression includes axial leakage, and iron saturation of the most narrow part of the magnetic circuit of the machine.</p><p>A computer program for optimization of PM motors with buried magnets has been developed. It was used to design the manufactured prototype PM integral motor, and the parameters are investigated with analytical and/or FEM calculations. The optimization program is also used to suggest nearoptimum pole numbers for desired powers (4-37 kW) and speeds (750- 3000 r/min) of inverter-fed PM motors. Results show that compact buried PM motors should have relatively large airgaps and high NdFeB-magnet masses to improve the efficiency. Ferrite magnets are unsuitable.</p><p>Measurements on the manufactured PM motor, the novel concept of stator integrated filter coils, and the complete PM integral motor are presented. Special attention was given to temperature and overall efficiency measurements.</p><p>The rotor cage losses were investigated by time-stepping FEM. Four short circuit fault conditions were also examined in order to evaluate the risks of demagnetization of the buried magnets. </p>

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Made available in DSpace on 2014-10-09T12:50:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:24Z (GMT). No. of bitstreams: 1 11097.pdf: 8468953 bytes, checksum: 884442a7a2e945eacad452d3697f2149 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Atlikus literatūros apžvalgą, remiantis teoriniais ir eksperimentiniais tyrimais, įsitikinta, kad elektromagnetiniai laukai turi įtakos žmogui ir aplinkai. Elektromagnetinio lauko poveikiui daugiausiai jautri centrinė nervinė ir neuroendokrininė sistemos. Didžiausi elektromagnetinių laukų šaltiniai, gyvenamojoje ir darbo aplinkoje, yra buitiniai prietaisai, elektros perdavimo, transformavimo ir skirstomieji įrenginiai. Elektros įrengimų kuriami elektromagnetiniai laukai, erdvėje sklinda pagal 1/r3; 1/r2 ir 1/r dėsnius. Tai charakteringa tiek elektrinių, tiek magnetinių laukų verčių kitimui. Elektromagnetinių laukų parametrų vertę apsprendžia elektros įrenginių įtampa, srovė ir tiriamo taško padėtis įrenginių atžvilgiu. Įvertinant labai platų mūsų šalies energetikos tinklą, naudojamų elektros įrenginių, kuriančių elektromagnetinius laukus gyvenamoje ir darbo aplinkoje, duomenys apie tai įgauna ženklią socialinę prasmę, sudaroma galimybė prognozuoti galimas silpnų elektromagnetinių laukų poveikio reikšmes, numatyti priemones joms pašalinti. / Literary review, according to theoretical and experimental researches, it was noticed that electromagnetic fields of industrial frequency influence the human and environment. The most sensitive parts to the effect of electromagnetic fields are the nervous system and the neuroendocrine system. The biggest sources of electromagnetic fields are the domestic appliances, the installations of electricity transmission, transference and the distributing installations in residential and working places. Electromagnetic fields are generated with electric installations and spread in space by 1/r3; 1/r2 and 1/r law. It is typical of the value change of electric and magnetic fields. Parameter value of electromagnetic fields is solved with electricity installations tension, stream and the location of analyzed point in point of installations. Summing up the wide energetic net of our country, the fact of usable electric installations (which create electromagnetic fields in residential and working places) assume the marked social signification, there is posed the opportunity to forecast the available values of low electromagnetic fields effect, and to forecast means to remove it.

Native plant communities and agricultural land are commonly converted to urban areas as cities across the Western United States continue to grow and expand. This expansion is typically accompanied by afforestation where a common goal among communities is to maximize shade tree composition. Planted forests in these regions are commonly composed of introduced tree species native to mesic environments and their ability to persist is dependent on consistent irrigation inputs. Many potential ecosystem services may be derived from planting trees in urban and suburban areas; however, there are also costs associated with extensive afforestation, and shade tree cover may have significant implications on municipal water budgets. In this study I evaluate variation in daily and seasonal water use of regionally common suburban landscape tree species in the Heber Valley (Wasatch County, Utah). I had two primary objectives: (1) to identify and understand the differences in transpiration between landscape tree species in a suburban setting and (2) to assess the sensitivity of sap flux and transpiration to variation in vapor pressure deficit, wind speed, and incoming shortwave radiation. I used Granier's thermal dissipation method to measure the temperature difference (ΔT) between two sap flux probes. The empirical equation developed by Granier was used to convert ΔT into sap flux density (Jo) measurements, which were then scaled to whole-tree transpiration. There were consistent and substantial differences in sap flux between tree species. I found that Picea pungens under irrigated growing conditions, on average, had Jo rates that were 32% greater and whole tree water use (ET) rates that were 550% greater than all other species studied. The findings of Jo may be partially explained by xylem architecture and physiological control over stomatal aperture. However, the rate of water flux in the outermost portion of sapwood does not necessarily determine the magnitude of whole tree transpiration. Rather, ET in this study was largely explained by the combined effects of irrigation, tree size, and sapwood to heartwood ratio.