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Full-Text Articles in Mechanical Engineering

Parametric Instability And Vibration Suppression Of Planetary Gear Transmissions Supported On Boundary Struts, Peng Guan Dec 2016

Parametric Instability And Vibration Suppression Of Planetary Gear Transmissions Supported On Boundary Struts, Peng Guan

Doctoral Dissertations

This dissertation explores the effects of discrete boundary strut properties on stability and vibration of the planetary gear transmission (PGT) driveline systems. Also, a robust output feedback control law is developed to actively control the PGT system vibrations. To better obtain boundary strut properties, a light-weight boundary strut design was developed for two popular boundary strut configurations by considering yield stress, buckling, and local buckling constraints. To facilitate analysis and development of the active control law, a comprehensive analytical PGT driveline system with elastic ring model, including gyroscopic effect and rotating-frame damping, is developed. The equation of motion of the …


Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood Aug 2016

Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood

Doctoral Dissertations

An estimate of the United States wind potential conducted in 2011 found that the energy available at an altitude of 80 meters is approximately triple the wind energy available 50 meters above ground. In 2012, 43% of all new electricity generation installed in the U.S. (13.1 GW) came from wind power. The majority of this power, 79%, comes from large utility scale turbines that are being manufactured at unprecedented sizes. Existing wind plants operate with a capacity factor of only approximately 30%. Measurements have shown that the turbulent wake of a turbine persists for many rotor diameters, inducing increased vibration …


Inter-Droplet Membranes For Mechanical Sensing Applications, Nima Tamaddoni Jahromi May 2016

Inter-Droplet Membranes For Mechanical Sensing Applications, Nima Tamaddoni Jahromi

Doctoral Dissertations

This dissertation combines self-assembly phenomena of amphiphilic molecules with soft materials to create and characterize mechanoelectrical transducers and sensors whose sensing elements are thin-film bioinspired membranes comprised of phospholipids or amphiphilic polymers. We show that the structures of these amphiphilic molecules tune the mechanical and electrical properties of these membranes. We show that these properties affect the mechanoelectrical sensing characteristic and range of operation of these membrane transducers. In the experiments, we construct and characterize a membrane-based hair cell embodiment that enables the membrane to be responsive to mechanical perturbations of the hair. The resulting oscillations of membranes formed between …