Master of Science, The Ohio State University, 2016, Mechanical Engineering

New experiments and minimal order analytical and computational models are developed and analyzed to investigate the variability of structure-borne noise and vibration due to tire/road interactions in the lower to mid-frequency regimes. The investigation focuses on a class of rear suspension systems that contain both direct and intersecting structural paths from the tire contact patches to the vehicle body. The structural paths intersect through a dynamically active rear subframe structure. Controlled operational experiments are conducted with a mass production minivan on a chassis dynamometer equipped with rough road shells. Unlike prior literature, the controlled experiments are analyzed for run-run variations in the structure borne noise up to 300 Hz in a single vehicle to evaluate the nature of excitations at the spindle as the key source of variation in the absence of significant manufacturing, assembly and instrumentation errors. Further, a deterministic, modal expansion approach is used to examine these variations. Accordingly, an eleven-degree-of-freedom reduced order lumped parameter half vehicle model is developed and is analytically utilized to demonstrate that left-right spindle excitation phasing dictates the participation of the subsystem vibrational modes in the system forced response. The findings are confirmed through the analysis of a reduced finite element model of the vehicle system with a high fidelity, modally dense suspension model, where the left-right rolling excitation phasing at the spindle alone is found to affect the component dynamic vibration amplitudes up to 30 dB depending upon the component location and frequency range. These results are in qualitative agreement with the type of variations observed in the experiments.

Committee: Rajendra Singh (Advisor); Scott Noll (Committee Member); Jason Dreyer (Committee Member) Subjects: Mechanical Engineering

Master of Science (M.S.), University of Dayton, 2015, Electro-Optics

Sparse aperture image synthesis requires proper phasing between sub-apertures. Phasing can be difficult due to hardware misalignments, atmospheric turbulence, and many other causes of optical path differences (OPD). Common synthesis techniques include incoherent and coherent methods. Incoherent methods utilize passive illumination and adaptive optics while coherent methods rely on active illumination and phase reconstruction approaches such as phase retrieval or spatial heterodyne. In this thesis, we present a partially coherent technique with the capability to use either active or passive illumination to digitally correct for piston phase errors. This technique requires an anamorphic pupil relay system and a piston correction algorithm. The anamorphic pupil relay causes two closely spaced sub-apertures in the entrance pupil to appear to be shifted further apart in the exit pupil. Analytic and numerical wave optics models demonstrate the effectiveness of this relay system, matching with experimental results. An analytic model shows that the higher frequency terms are equivalent to scaled cross-correlations of the two sub-apertures, which are shifted due to the anamorphic separation. The constant shifts due to the separation are found experimentally using a registration algorithm with a calibration target. The cross-correlations are dependent on the piston phase errors between sub-apertures. We show that a piston correction algorithm can be used to shift the cross-correlations to their original positions dictated by the entrance pupil, multiply a cross-correlation with the complex conjugate of the auto-correlation, use the summation of this product to calculate the piston, and correct the phase error in each cross-correlation before recombining them with the auto-correlation. Examples show diffraction limited results for both simulated and experimental images that are supported by analytical, numerical, and experimental analysis of the system's modulation (open full item for complete abstract)

Committee: David Rabb Ph. D (Advisor); Matthew Dierking Ph. D (Committee Member); Edward Watson Ph. D (Committee Member) Subjects: Electrical Engineering; Optics; Physics; Remote Sensing

Master of Arts (MA), Bowling Green State University, 2011, German

This study examines Steve Reich's reflections on his early works in the context of Walter Benjamin's thesis in “The Work of Art in the Age of its Technical Reproducibility.” While Reich's thoughts as expressed in interviews and selected writings show a similar attitude to Benjamin's toward changes in human perception, Benjamin's notion of auratic demise in the age of technical reproducibility is challenged by Reich's understanding of the role of technology in music and the effects of gradual musical processes. Reich's assertions regarding the aesthetic autonomy of his compositional process are reminiscent of Romantic ideals of art, particularly those embodied by the “poeticized” as defined by Benjamin in “Two Poems by Friedrich Holderlin.” However, the means by which Reich claims to have reintroduced artistic autonomy are those that Benjamin attributes to aura's deterioration, such as impersonality and gradual presentation of the artistic subject. This study determines that, while Reich uses mechanical process to accommodate the change in human perception as Benjamin anticipates, aura is not eliminated as proposed in “The Work of Art in the Age of its Technical Reproducibility.” Although the “here and now” of the original is destroyed, aura survives through the authority and transcendent nature of musical process, and singularity is achieved by the unique reception of individual audience members with each hearing. Reich's work may not politicize aesthetics as Benjamin predicts, but through the authority of autonomous musical process and the decentralization of interpretation, the fascist aestheticization of politics may still be averted in the age of technical reproducibility.

Committee: Edgar Landgraf Dr. (Advisor); Geoffrey Howes Dr. (Committee Member) Subjects: Germanic Literature