Digital Commons Network^™

Biped Dynamic Walking Using Reinforcement Learning, Hamid Benbrahim

Doctoral Dissertations

This thesis presents a study of biped dynamic walking using reinforcement learning. A hardware biped robot was built. It uses low gear ratio DC motors in order to provide free leg movements. The Self Scaling Reinforcement learning algorithm was developed in order to deal with the problem of reinforcement learning in continuous action domains. A new learning architecture was designed to solve complex control problems. It uses different modules that consist of simple controllers and small neural networks. The architecture allows for easy incorporation of modules that represent new knowledge, or new requirements for the desired task. Control experiments were …

Nitrogen Oxide Decomposition By Barrier Discharge, Christopher Rob Mclarnon

Doctoral Dissertations

Nitrogen oxides have been linked to numerous air pollution problems including the production of ozone in the troposphere and acid rain. Annual nitrogen oxides emissions in the United States exceed 21 million tons and are primarily a result of the high temperature combustion of fossil fuel. Recent regulations in the U.S., both federal and state, require that nitrogen oxides emissions be reduced over the next several years.

Control of nitrogen oxide emissions is difficult in combustion exhaust gases because of their low concentration and reactivity. Numerous technologies have been developed to reduce emissions but the costs are generally high and …

Ecophysiology Of Metal-Reducing Aeromonas And Shewanella Strains From Great Bay Estuary, Victoria Knight

Doctoral Dissertations

The seasonal abundance and distribution of mesophilic aeromonads at seven sites in Great Bay Estuary, NH were monitored over a 24 month period. Total heterotrophic bacteria, total and fecal coliforms, salinity, temperature, pH, total suspended solids, and chlorophyll were also measured in the samples. Aeromonads were isolated at each site throughout the year with the highest incidence and population density in the late summer to early fall. Aeromonad abundance correlated positively with the incidence of coliforms, temperature, and salinity.

Aeromonas hydrophila ATCC 7966 grew anaerobically by using NO$\sb3\sp-$, fumarate, Fe (III), Co (III), or Se (VI) as terminal electron acceptors. …

Analysis And Design Of Ac Induction Motors With Squirrel Cage Rotors, Shine Ho

Doctoral Dissertations

The traditional approach to modelling the AC induction motor revolves around the well-known equivalent "T" circuit model. In this approach, the direct connection from geometry to performance is suppressed. For better understanding of magnetic, electrical, and thermal behaviors, three lumped models based on the actual geometry are developed in this dissertation. Based on these lumped models, an iterative design model is also developed.

In order to analyze and design induction motors, the relationships of basic motor variables to motor performance must be known. For determining the relationships, three new mathematical lumped models are developed. The magnetic model describes flux behavior. …

Fume Generation In Gas Metal Arc Welding, Robert V. Albert

Doctoral Dissertations

This investigation studied fume generated from Gas Metal Arc Welding (GMAW). Through an extensive literature review, experimental measurements and analytical reasoning this dissertation answers four questions. Why and how does oxygen content of the shield gas effect fume generation? Why is more fume generated with helium than with argon as a shield gas? Why and how does welding mode affect fume rate? Why and how does pulsing the current lower fume generation rate?

An extensive literature survey was conducted. The current view of GMAW indicates that four modes exist in metal transfer across the arc. Each mode selects from several …

Full-Scale Comparative Evaluation Of Two Slow Sand Filter Cleaning Methods, Jan A. Kem

Doctoral Dissertations

Slow sand filters are an established treatment method for water with low turbidity. They usually are effective for the removal of turbidity, microorganisms (including cysts of Giardia and Cryptosporidium), and particles, but they require significant periods of time for cleaning. In the 1950's, West Hartford, CT developed a harrowing process to reduce the time and labor required for cleaning at that plant. A 1988 study observed those filters had higher removal rates for non-particulate dissolved organic carbon and UV absorbing materials, surrogates for trihalomethane formation, than did filters at two other plants cleaned by the conventional scraping method.

This study …