Thesis (M.S.)--Ohio University, August, 2004. / Title from PDF t.p. Includes bibliographical references (leaves 62-63).

Thesis (M.S.)--California Polytechnic State University, 2010. / Title from PDF title page; viewed on June 21, 2010. Major professor: Richard Savage, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Engineering with Specialization in Materials Engineering." "June 2010." Includes bibliographical references (p. 44-45).

Thesis (M.S.)--Ohio State University, 1985. / Includes bibliographical references (leaves 151-153). Available online via OhioLINK's ETD Center

Effective dipole moment method has been widely accepted as the de facto technique in predicting the dielectrophoretic force due to the non-uniform electric field. In this method, a finite-particle is modeled as an equivalent point-dipole that would induce a same electric field under the external electric field. This approach is only valid when the particle size is significantly smaller than the characteristic length of interest. This assumption is often violated in a microfluidic device, where the thickness or width of the microchannel can be as small as the particle. It is shown in this numerical study that when the dimensions of the particle were in the same order of magnitude as the characteristic length of the device, dielectrophoretic force can be induced even in a uniform electric field. This force arises due to the disturbance of the particle and the bounding wall. / Singapore-MIT Alliance (SMA)

Orientador: Dimitar Kolev Dimitrov / Banca: Ana Paula Peron / Banca: Cleonice Fátima Bracciali / Resumo: Nesta dissertação estudamos a conjectura de Smale junto com a maioria dos resultados sobre este assunto e sua interpretação eletrostática. Mostramos alguns testes numéricos sobre a citada conjectura, para podermos analisar sua interpretação eletrostática. / Abstract: In this dissertation we study a conjecture of smale together with majority of results about this topic and its electrostatic interpretation. We show some numerical tests concerning the conjecture in order to analise its electrostatic interpretation. / Mestre

M.Ing. / Variable liquid resistors are utilised in the rotor circuit, to control mine winders using slipring induction machines. These liquid resistors have a number of disadvantages, therefore a new drive technology is required to replace liquid controllers. A number of machine drives are discussed and a comparative study is made. A 22kW resistively loaded buck chopper in the rotor, is used as a case study. Full design details and procedures are given for the chopper. These designs are verified by simulations and experimental results. A current control was designed and implemented for the buck chopper in the rotor, using a PI controller and pulse width modulation. The 22kW resistively loaded buck chopper operated exceptionally well and it is evident that it could be a viable method for replacing liquid controllers. The oscillation generated in the hoist cables are discussed and a possible counter acting acceleration method of removing these oscillations is described. A rotating oscillation system was designed and constructed for experimental purposes. From the tests undertaken on the experimental system, it was evident that by the implementation of the counter action process, it is possible to remove the oscillations in the hoist ropes.

In this study, we present analytical and experimental investigation of electrically actuated micro cantilever based resonators. These devices are fabricated using polyimide and coated with chrome and gold layers from both sides. The cantilevers are highly curled up due to stress gradient, which is a common imperfection in surface micro machining. Using a laser Doppler vibrometer, we applied a noise signal to experimentally find the first four resonance frequencies. Then, using a data acquisition card, we swept the excitation frequency around the first four natural modes of vibrations. Theoretically, we derived a reduced order model using the Galerkin method to simulate the dynamics of the system. Extensive numerical analysis and computations were performed. The numerical analysis was able to provide good matching with experimental values of the resonance frequencies. Also, we proved the ability to excite higher order modes using partial electrodes with shapes that resemble the shape of the mode of interest. Such micro-resonators are shown to be promising for applications in mass and gas sensing.

The purpose of the project described in this paper has been to complete construction and to determine the operating characteristics of a charging system and a corona-type controlled leakage system for the compact Van de Graaf generator now under construction at North Texas State University. Calibration data of the generating voltmeter to be used for determining the potential developed by the generator are also included in the paper.

<p> The limitations of the conventional control system due to the corona discharge are discussed. An improved system employing a parallel feedback loop to modulate the terminal stripper is described. Finally an experiment is described whereby the performance of this system is measured and compared with the original system performance.</p> / Thesis / Master of Science (MSc)

published_or_final_version / Electrical Engineering / Doctoral / Doctor of Philosophy