The development of a power electronic circuitry for a flywheel energy storage system is discussed in the following aspects. First, due to the nature of permanent magnet brushless DC motor/generator, the operation of three-phase voltage source inverter/rectifier can be simplified to that of a bi-directional DC-DC converter, allowing the use of mostly analog control. Second, there is a problem associated with the existing six-step brushless DC motor/generator control in the generator mode. A twelve-step control scheme is proposed to solve this problem. Third, high-switching frequency is necessary for the flywheel charger/discharger in order to reduce the size/weight of the system and to synthesize the high-frequency motor/generator current waveforms. A working prototype demonstrates that a high efficiency can be achieved at 1 ~O-kHz switching frequency by the innovative ZVT soft-switched three-phase inverter/rectifier. / Master of Science

The research presented in this dissertation is carried out in two parts; the first, which is the main work of this dissertation, involves development of continuous differentiability of the solution with respect to the unknown parameters. For linear parabolic partial differential equations, only mild conditions are assumed on the admissible parameter space. The nonlinear partial differential equation we consider is a generalized Burgers’ equation, for which we establish the well-posedness and the smoothness properties of the solution with respect to the parameters. In the second part, we consider parameter identification problems for these two parameter dependent systems. The identification scheme which we use here is the quasilinearization method. Based on the results in the first part of this work, we obtain existence and local convergence of the algorithm. We also present some numerical examples which demonstrate the performance of the quasilinearization scheme. / Ph. D.

The importance of taxol as an anticancer drug lies not only in its activity in antitumor assays but also in its unique mechanism of action. Unfortunately, taxol is not water-soluble and therefore must be given in conjunction with emulsifying agents. Modifications of taxol were carried out in order to prepare water-soluble taxol derivatives. The C-2’ hydroxyl group of taxol was substituted with various groups to increase water solubility. The synthesized taxol derivatives, 2’-((3-sulfo-1-oxopropyl)oxy)taxol sodium salt, 2’-((4-((2-sulfoethyl)amino)-1,4-dioxobutyl)oxy)taxol sodium salt, and 2’-((4-((3-sulfopropyl)amino)-1,4-dioxobutyl)oxy)taxol sodium salt were more water-soluble than taxol. The synthetic pathways to these compounds are compared and discussed. / Master of Science

Master of Science

This thesis presents an artificial neural network (ANN) approach to diagnose and detect faults in oil-filled power transformers based on dissolved gas-in-oil analysis. The goal of the research is to investigate the available transformer incipient fault diagnosis methods and then develop an ANN approach for this purpose. This ANN classifier should not only be able to detect the fault type, but also should be able to judge the cellulosic material breakdown. This classifier should also be able to accommodate more than one type of fault. This thesis describes a two-step ANN method that is used to detect faults with or without cellulose involved. Utilizing a feedforward artificial neural network, the classifier was trained with back-propagation, using training samples collected from different failed transformers. It is shown in the thesis that such a neural-net based approach can yield a high diagnosis accuracy. Several possible design alternatives and comparisons are also addressed in the thesis. The final system has been successfully tested, exhibiting a classification accuracy of 95% for major fault type and 90% for cellulose breakdown. / Master of Science