The work presented in this thesis contributes to the understanding of the dynamic behaviour of large power transformer windings under short circuit forces. A simple yet accurate method of prediction of electromagnetic forces is developed and used as input to the dynamic mechanical model. In develop- ing this model the mechanical properties of oil-impregnated pressboard have been investigated and measured in a specially designed rig which simulates the typical power transformer environment. Assumptions have been made regarding these properties to enable them to be meaningfully incorporated in a dynamic model of a transformer. Predictions made using the model have been compared with actual measurements on a transformer and a correlation within 20%-30% was achieved. The work demonstrated the importance of mechanical prestress to ensure that no serious nonlinearities will be encoun- tered in the mechanical behaviour when short-circuit forces are present in a power transformer. It was also found that for small radial deflections, the axial and radial behaviours are independent. This work provides a theoreti- cal basis for further work in which precise determinations of the mechanical properties of oil-impregnated pressboard can be used to model the dynamic behaviour of a large transformer to a high degree of accuracy.

No description available.

No description available.

Thesis (M.S.)--Boston University

This paper investigates factors that contribute to the growth in electric vehicle sales using a regression analysis. I study the effects of five factors through five different regressions on the data set that includes information on electric vehicle (EV) sales, gas price, unemployment rate, passenger car sales, personal income, and miles traveled from January 2012 to December 2018. I also test the interactive effect between factors to see whether the magnitude of impact on electric vehicle sales of certain independent variable will change based on the value of another independent variable. The implication of my study is that gas price and personal income positively affect the EV sales. The unemployment rate and miles traveled are negatively correlated with EV sales. Moreover, the impact of gas price, income, and miles traveled change when the passenger car demand is different. Personal income level will also determine how sensitive people are to gas price when purchasing electric vehicles.

Copy of published work by the author, entitled: Thermionic emission. London : Chapman & Hall, 1934, submitted together with the reprints / Title supplied by cataloguer / Lacks title page or contents. / Includes bibliographical references. / 5 items : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A collection of 5 of the author's papers; offprints from various journals, submitted as the author's Doctor of Science thesis. The work leading to the publications was done for the General Electric Company, in their Research Laboratories, and for the Marconiphone Company / Thesis (D.Sc.)--University of Adelaide, 1935

Thesis (Ph. D.)--Oregon State University, 1963. / Typescript. Includes bibliographical references (leaves 53-55). Also available on the World Wide Web.

Advancements in power electronics to higher power levels and faster switching times allow new machine and systems designs, but also create higher stresses on electric machinery insulation. High performance, pulse-width modulated (PWM) inverters are now available for medium voltage drive systems, and are being considered by the U.S. Navy as they move to the "all-electric" ship. If this process is to be successful, a necessary component will be to understand the impact of partial discharge (PD) generation on electric drive systems. Out of the many PD influencing parameters, voltage level, voltage rise-time, switching frequency, and temperature were chosen to be investigated with regards to their influence on PD generation in a comprehensive research project in the Motor Systems Research Facility (MSRF) at Oregon State University (OSU). The tests were performed on representative propulsion coils employing two different 4160 V insulation systems and were evaluated by both an optical and electrical PD detection method. A highly flexible test configuration was developed, capable of adjusting each of the four test parameters independently over a wide range of appropriate values. The developed test program enabled the analysis of the influence of the parameters on the generation of PD, as well as an evaluation of the test coils and PD instrumentation used. It is concluded that, as expected, voltage level is the most significant parameter affecting PD production. However, there is a surprising interdependence of rise-time and pulse-width that requires further investigation. Multiple-cycling tests are seen as appropriate to determine the effect of temperature. Based on the subjective nature of the findings from the test program an improved PD instrument is proposed, which would increase the capabilities and objectivity of the PD detection process. / Graduation date: 2004

The exponentially tapered, nonuniform transmission' line, applied as an impedance transformer, is analyzed and modified. The analysis develops an expression for the input reflection coefficient that has the magnitude and phase as distinct functions. This allows ease in comparing the approximate and exact solutions and in developing the S-parameters for the taper. The modification is a slight change in the taper's shape that yields a significant reduction in the passband reflection coefficient (a tapered line is an impedance-transforming, high -pass filter) with only a slight increase in the taper's length. This modification is accomplished without sacrificing the exponential line's simple, closed-form expressions for both the reflection coefficient and the variation of impedance along the taper. These expressions are subjected to experimental verification. / Graduation date: 1975

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.