The object of this thesis was to present the method and results of an experimental determination and correlation of the drag coefficients of accelerating spheres.

This thesis deals with the concepts of a very interesting phenomenon in quantum physics, the Casimir effect. Here the effect is investigated in detail and its importance to other areas of physics is analysed. The Casimir effect is produced by disturbing the vacuum energy when material boundaries or background fields are introduced in the vacuum. The usual approach to this effect is the vacuum fluctuation that has been studied in the past in relation to the discussion of the zero-point energy as a result of the field resemblance to the quantum harmonic oscillators, where residual ground state energy must be considered. In this thesis a new method to study vacuum fluctuations is presented. This new approach to the problem which is more classical is based on the Heisenberg uncertainty principle and the very important fluctuation-dissipation theorem. The other aim of the thesis is to implement a new algorithm for regularizing the Casimir energy for a massive scalar field. Unlike the previous works on this problem by other authors that give approximate results, this attempt will produce precise results. My method is based on a new regularization procedure that allows us to employ the very reliable dimensional regularization scheme in place of a more mathematically complicated zeta-function regularization procedure. In order to achieve this goal I will deal with the problem by using the Euler-Maclaurin summation formula. The result will be a regularized Casimir energy for the case of a massive scalar field. This model may be used for the other geometrical boundaries and different fields. / Doctor of Philosophy (PhD)

Thesis (M.S.M.E.)--University of Delaware, 2009. / Principal faculty advisor: Xinyan Deng, Dept. of Mechanical Engineering. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 154-156).

Thesis (M.S.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaves 73-75).

Thesis (Ph. D.).--Catholic University of America, 1939. / Includes bibliographical references (p. 117-120).

Cellular adhesion plays a crucial role in the biological function of cells, allowing them to communicate and signal, as well as physically anchor, by enabling them to adhere to either other cells or the extra cellular matrix (ECM). This process is regulated by several factors including intrinsic bond kinetics, internal cellular signaling, environment, force exerted on the bond, and force history of the bond. Concerning the force and force history dependence, the observation of catch bonds in integrin binding has asked as more questions than it has answered. To explore the force and force history dependence this process, each bond was loaded to a peak force before relaxing to a much lower force that was held for the duration of the measurement. Two different integrins were studied, both of which have in previous works exhibited a catch bond. Furthermore, the effects of different metal ion conditions and an allosteric antagonist were also studied to elucidate the conformational effects on force priming of integrin. What was observed was that I domain, or αA domain, possessing integrin, whether tested against its more active or less active binding state, changed very little in terms of off rate once the priming force was applied. However in the I domain, or αA domain, lacking integrin, the observed off rate changed as well. It seems that force priming is capable of causing integrin to bind in a stronger manner regardless of the other conditions used to either activate or inhibit binding. However the way in which the binding is strengthened depends on the receptors structure.

Thesis (M Arch)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: John Brittingham. Includes bibliographical references (leaves 90-92).

Electromechanical modeling efforts in the research field of vibration-based energy harvesting have been mostly focused on deterministic forms of vibrational input as in the typical case of harmonic excitation at resonance. However, ambient vibrational energy often has broader frequency content than a single harmonic, and in many cases it is entirely stochastic. As compared to the literature of harvesting deterministic forms of vibrational energy, few authors presented modeling approaches for energy harvesting from broadband random vibrations. These efforts have combined the input statistical information with the single-degree-of-freedom (SDOF) dynamics of the energy harvester to express the electromechanical response characteristics. In most cases, the vibrational input is assumed to have broadband frequency content, such as white noise. White noise has a flat power spectral density (PSD) that might in fact excite higher vibration modes of an electroelastic energy harvester. In particular, cantilevered piezoelectric energy harvesters constitute such continuous electroelastic systems with more than one vibration mode. The main component of this thesis presents analytical and numerical electroelastic modeling, simulations, and experimental validations of piezoelectric energy harvesting from broadband random excitation. The modeling approach employed herein is based on distributed-parameter electroelastic formulation to ensure that the effects of higher vibration modes are included. The goal is to predict the expected value of the power output and the mean-square shunted vibration response in terms of the given PSD or time history of the random vibrational input. The analytical method is based on the PSD of random base excitation and distributed-parameter frequency response functions of the coupled voltage output and shunted vibration response. The first one of the two numerical solution methods employs the Fourier series representation of the base acceleration history in a Runge-Kutta-based ordinary differential equation solver while the second method uses an Euler-Maruyama scheme to directly solve the resulting electroelastic stochastic differential equations. The analytical and numerical simulations are compared with several experiments for a brass-reinforced PZT-5H cantilever bimorph under different random excitation levels.In addition to base-excited cantilevered configurations, energy harvesting using prismatic piezoelectric stack configurations is investigated. Electromechanical modeling and numerical simulations are given and validated through experiments for a multi-layer PZT-5H stack. After validating the electromechanical models for specific experimentally configurations and samples, various piezoelectric materials are compared theoretically for energy harvesting from random vibrations. Finally, energy harvesting from narrowband random vibrationsusing both configurations are investigated theoretically and experimentally.

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