Master of Science, The Ohio State University, 2011, Mechanical Engineering

Wind energy has received a great deal of attention in recent years in part due to its minimal environmental impact and improving efficiency. Increasingly complex wind turbine gear train designs, well-known rolling element bearing failures, and the constant push to manufacture more reliable, longer lasting gear trains generate the need for more advanced analysis techniques. The objectives of this thesis are to examine the mechanical design of Orbital2 flexible pin, multi-stage planetary wind turbine gear trains using three dimensional finite element/contact mechanics models. These models are constructed and analyzed using software that specializes in elastic gear tooth contact. Computational results, such as gear tooth root strain, are compared to full system experiments. Root strain is calculated at multiple locations across the facewidth of ring gears from the computational models and compared to experimental data. Computational results for tooth load distribution and planet load sharing factor are compared to experiments. The computational models consider gear misalignment and carrier eccentricity and permit design recommendations for improving tooth load distribution and planet load sharing.

Committee: Robert Parker PhD (Advisor); Sandeep Vijayakar PhD (Committee Member) Subjects: Design; Energy; Engineering; Mechanical Engineering; Mechanics

Doctor of Philosophy, Case Western Reserve University, 2009, Biomedical Engineering

The advent of the genomic age is revolutionizing the experimental cardiovascular research irreversibly. Dissecting molecular switches that control the changes of cardiac physiology with transgenic mouse models has proven to offer important insights into the control of cardiac function. The integration of novel MR tissue tracking techqniques with these genetically manipulated mice may allow comprehensive characterization of contractile dysfunction non-invasively at the earliest diseased stages, thus facilitate our understanding of the pathogenesis of human cardiac diseases. In the current thesis, we aimed at developing fast and accurate MR tissue tracking techniques and applying them for the assessment of ventricular function in transgenic mouse models of cardiac diseases. First, spatial modulation of magnetization (SPAMM) tagging was implemented in the mouse heart; and a 3D SPAMM tagging analysis method was developed based on harmonic phase (HARP) and homogeneous strain analysis. Using this 3D tagging analysis method, longitudinal strain and circumferential-longitudinal shear was quantified in addition to the 2D ventricular wall strain. Second, to improve the limited tagging resolution of existing SPAMM techniques, a HARP-based high-resolution tagging analysis method was proposed in mouse. The utility of such method was demostrated by quantifying the transmural heterogeneity of the left ventricle. Third, a 2D multi-phase displacement encoding with stimulated echoes (DENSE) imaging and analysis method was developed which allows direct and automatic Lagrangian strain quantification with high spatial and temporal resolution. Additionally, the utility of this multi-phase DENSE method was demonstrated in mouse both at baseline and with high workload. Functional enhancement was identified upon dobutamine stimulation both at the global and the regional levels. Fourth, for the evaluation of longitudinal wall motion within the short axis (SA) plane, 2D multi-phase DENSE ima (open full item for complete abstract)

Committee: XIN YU (Committee Chair); DAVID WILSON (Committee Member); MARK GRISWOLD (Committee Member); CHRIS FLASK (Committee Member); BRIAN HOIT (Committee Member) Subjects: Biomedical Research; Engineering