Digital Commons Network^™

Design And In Situ Testing Of A Piezometer System To Measure Earthquake -Induced Pore -Pressure Changes, Robert Farrell

Doctoral Dissertations

Pore pressure changes have been measured in fine sand deposits that are known to have liquefied during earthquakes. Some of the measured signals have not been similar to what was expected during earthquake-induced liquefaction. Using artificially generated signals, several investigators have attempted to determine if existing piezometer fields designed to measure earthquake induced pore pressure changes are operating correctly. The signals generated during one investigation were not similar to those expected from an earthquake. In another investigation, while the generated signals were similar to ones expected from an earthquake, the results were not reproducible; the generated signals damaged the aquifer …

Assessment Of The Fate Of Cryptosporidium Parvum, Giardia Lamblia And Ascaris Lumbricoides In Class A Composting And Class B Lime Stabilization Biosolids Treatment Processes, Christine L. Bean

Doctoral Dissertations

The management of biosolids in the United States has become an issue of public health concern in regard to disposal. Congress created the Clean Water Act in 1972 to protect waters in the United States and as a result, no longer can human waste be dumped into oceans or rivers. Means of disposal of biosolids are focused on land application today. The practice of land application takes into consideration the classification of the biosolids material and management practices to control access to and growth of crops on the land. Biosolids are classified as either Class A or Class B depending …

The Impact Of Coating Architecture On The Hardness, Friction And Wear Resistance Of Hard And Tribological Nanocomposite Coatings, Jose Luis Endrino

Doctoral Dissertations

Future generations of mechanical systems will place new demands on the tribological performance of interacting surfaces. Vapor-deposited surface coatings can provide extended lifetimes, increased efficiencies and energy savings for mechanical components and tools. These benefits can also be extended to space mechanisms and satellites with the use of vacuum solid lubricants. The material properties of surface coatings such as hardness, friction, and wear resistance in a particular environment are influenced by the characteristics of the coating microstructure which include density, grain size, grain boundary chemistry, porosity, and grain orientation.

In this research effort bias sputter deposition, co-sputtering, and magnetron sputtering-pulsed …

Active Disturbance Cancellation In Nonlinear Dynamical Systems Using Neural Networks, John C. Canfield

Doctoral Dissertations

A proposal for the use of a time delay CMAC neural network for disturbance cancellation in nonlinear dynamical systems is presented. Appropriate modifications to the CMAC training algorithm are derived which allow convergent adaptation for a variety of secondary signal paths. Analytical bounds on the maximum learning gain are presented which guarantee convergence of the algorithm and provide insight into the necessary reduction in learning gain as a function of the system parameters. Effectiveness of the algorithm is evaluated through mathematical analysis, simulation studies, and experimental application of the technique on an acoustic duct laboratory model.

A Wavelet-Based Cmac For Enhanced Multidimensional Learning, Brian P. Kirk

Doctoral Dissertations

The CMAC (Cerebellar Model Articulation Controller) neural network has been successfully used in control systems and other applications for many years. The network structure is modular and associative, allowing for rapid learning convergence with an ease of implementation in either hardware or software. The rate of convergence of the network is determined largely by the choice of the receptive field shape and the generalization parameter. This research contains a rigorous analysis of the rate of convergence with the standard CMAC, as well as the rate of convergence of networks using other receptive field shape. The effects of decimation from state-space …

In-Situ Study Of The Influence Of Additives On The Growth Behavior Of Copper Electrodeposits On Copper Single Crystal, Aiwen Wu

Doctoral Dissertations

Trace organic additives are known to be essential in obtaining desired metal electrodeposits in the microelectronic industry, however, fundamental design principles for their use and a scientific understanding of their interaction during electrodeposition is lacking. In the present study we investigated electrodeposition of copper on the Cu(100) surface in air-saturated or dearated acid-sulfate plating solutions containing several combinations of chloride and additives benzotriazole (BTA) and 3-mercapto propane sulfonic acid (MPSA) under galvanostatic pulse-current conditions. The electrodeposition process was followed using in-situ atomic force microscopy (AFM). AFM images were quantitatively analyzed by pattern-recognition and scaling procedures.

In the absence of additives, …

Some Contributions To The Hydraulic Characterization Of Fractured Bedrock Formations, Gonzalo Pulido

Doctoral Dissertations

During 3 years of investigation at the BBC field site, research has led to developments in bedrock monitoring, groundwater sampling, formation hydraulic testing, and the conceptual model of formation hydraulics. This dissertation presents a field device, two hydraulic test methods, and one method of hydraulic test analysis developed to assist in the hydraulic characterization of fractured bedrock formations. It also presents the use of these tools in the development of the Conceptual Hydrogeologic Model for a fractured bedrock formation contaminated with chlorinated solvents. The field device was named the Multipurpose Packer System (MPS), a discrete-interval isolation system for the sampling …