Engineering Commons^™

One-Dimensional Radial Flow Turbomachinery Performance Modeling, Robert John Pelton

Theses and Dissertations

The Two-Element In Series (TEIS) and Two-Zone models have been used successfully for over twenty years to model test data for radial flow compressors and pumps. The models can also be used to predict the performance of new machines provided that the model inputs can be accurately specified. Unfortunately, use of the TEIS and Two-Zone models as a predictive tool has been limited because an accurate and broadly applicable method of predicting the modeling parameters, etaA, etaB, chi and d2p does not exist. Empirical models have been developed to predict the TEIS and Two-Zone modeling parameters based on a large …

Shear Modulus Degradation Of Liquefying Sand: Quantification And Modeling, Peter A. Olsen

Theses and Dissertations

A major concern for geotechnical engineers is the ability to predict how a soil will react to large ground motions produced by earthquakes. Of all the different types of soil, liquefiable soils present some of the greatest challenges. The ability to quantify the degradation of a soil's shear modulus as it undergoes liquefaction would help engineers design more reliably and economically. This thesis uses ground motions recorded by an array of downhole accelerometers on Port Island, Japan, during the 1995 Kobe Earthquake, to quantify the shear modulus of sand as it liquefies. It has been shown that the shear modulus …

In Situ Photopolymerized Hydrogels For Enhancing Protein Delivery, Chien-Chi Lin

All Dissertations

In recent years, there has been immense interest in the utilization of photopolymerized hydrogels as carriers for controlled protein delivery and cell scaffolds for tissue engineering applications. Although poly(ethylene glycol) (PEG)-based hydrogels formed from mild photopolymerization methods have been suggested as biocompatible matrices that allow for safely encapsulating biomolecules including proteins, peptides, DNA, and cells, the adverse effects of photopolymerization reactions on the encapsulated proteins have largely been overlooked. In addition, conventional hydrophilic hydrogels fail to effectively control protein delivery rates due to their high permeability. These two problems are critical since the delivery of protein therapeutics from hydrogel matrices …

Gate Level Dynamic Energy Estimation In Asynchronous Circuits Using Petri Nets, Ryan Mabry

USF Tampa Graduate Theses and Dissertations

This thesis introduces a new methodology for energy estimation in asynchronous circuits. Unlike existing probabilistic methods, this is the first simulative work for energy estimation in all types of asynchronous circuits.

The new simulative methodology is based on Petri net modeling. A real delay model is incorporated to capture both gate delays and interconnect delays. The switching activity at each gate is captured to measure the average dynamic energy consumed per request/acknowledge handshaking pair. The new type of Petri net is called Hierarchical Colored Asynchronous Hardware Petri net (HCAHPN). The HCAHPN is able to capture the temporal and spatial correlations …

Modeling Of Liquid Crystal Display And Photonic Devices, Zhibing Ge

Electronic Theses and Dissertations

Liquid crystal (LC) materials have been widely applied in electro-optical devices, among which display is the most successful playground and numerous new applications in photonic areas (such as laser beam steering devices) are also emerging. To well guide the device design for optimum performance, accurate modeling is of prior and practical importance. Generally, the modeling of LC devices includes two parts in sequence: accurate LC molecule deformation extraction under external electric fields and optical calculation thereafter for the corresponding electro-optical behaviors. In this dissertation, first, hybrid finite element method and finite difference method are developed to minimize the free energy …

An Investigation Of Size Exclusion And Diffusion Controlled Membrane Fouling, Colin Michael Hobbs

Electronic Theses and Dissertations

The reduction of membrane productivity (i.e. membrane fouling) during operation occurs in virtually all membrane applications. Membrane fouling originates from the method by which membranes operate: contaminants are rejected by the membrane and retained on the feed side of the membrane while treated water passes through the membrane. The accumulation of these contaminants on the feed side of the membrane results in increased operating pressures, increased backwashing frequencies, increased chemical cleaning frequencies, and increased membrane replacement frequencies. The most significant practical implication of membrane fouling is increased operating and maintenance costs. As such, membrane fouling must be properly managed to …

Four Terminal Junction Field-Effect Transistor Model For Computer-Aided Design, Hao Ding

Electronic Theses and Dissertations

A compact model for four-terminal (independent top and bottom gates) junction field-effect transistor (JFET) is presented in this dissertation. The model describes the steady-state characteristics with a unified equation for all bias conditions that provides a high degree of accuracy and continuity of conductance, which are important for predictive analog circuit simulations. It also includes capacitance and leakage equations. A special capacitance drop-off phenomenon at the pinch-off region is studies and modeled. The operations of the junction fieldeffect transistor (JFET) with an oxide top-gate and full oxide isolation are analyzed, and a semi-physical compact model is developed. The effects of …

Experimental And Modeling Studies Of Contaminant Transport In Capped Sediments During Gas Bubble Ebullition, Qingzhong Yuan

LSU Doctoral Dissertations

Fluxes of the three organics and eighteen metals from sediments were measured with diffusion chambers, and the effectiveness of a sand cap ascertained. The influence of sediment consolidation on contaminant flux and the mass transfer coefficient at the sediment-water interface was studied. A two-layer diffusion-advection model and consolidation model were coupled to elucidate the effect of sediment consolidation on chemical transport in the sediment-cap system. The model was tested and verified by the experimental data from microcosms, and then was used to predict phenanthrene flux under field conditions. The simulation results showed that consolidation could accelerate phenanthrene breakthrough and enhance …

Turbulence Modeling For Film Cooling Flows, Asif Hoda

LSU Doctoral Dissertations

An improved two equation turbulence model has been developed in this dissertation to better predict the complex film cooling flow field that is formed from the interaction of a coolant jet and a crossflow over a modeled turbine blade surface. Film cooling of turbine blades is commonly employed to effectively protect turbine blades from thermal failure and thereby to allow higher inlet temperatures in order to increase the efficiency of gas turbine engines. Film cooling involves the injection of rows of coolant jets from slots on the surface of a turbine blade which is then bent over by the crossflow …

An Initial Methodology For The Definition And Implementation Of Unmanned Aerial Vehicle Agent Behaviors, William Eric Marsh

Browse all Theses and Dissertations

In many current agent-based modeling systems, it is difficult for a domain-expert user to define and implement agent behaviors without possessing extensive programming knowledge. MUAVES is an existing simulation environment that serves as a research testbed for examining command and control issues with unmanned aerial vehicle (UAV) systems containing many vehicle agents. In its previous form, defining agent behaviors required knowledge of the C# programming language that some MUAVES users did not have. This thesis presents a new methodology for the definition and implementation of UAV agent behaviors in MUAVES. The new methodology is based on diagramming an agent's controller …

Modeling And Simulation Of A Microturbine Generator To Be Coupled With A Molten Carbonate Fuel Cell For Distributed Generation, Karleine M. Justice

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Distributed generation is desired when the individual energy requirements ranging from 25-75 kW of office buildings, restaurants, hospitals and apartments can not be met by the current electric utility grid. Microturbine generators as stand alone power generation systems have been designed to meet these requirements. For power requirements up to 50 MW, hybrid fuel cell systems offer higher efficiency and lower levels of pollutant emissions with more advanced fuel energy savings than non-hybrid systems. The objective of this project is to develop a simulation of a microturbine generator as a stand alone power generation system to validate a microturbine generator …

Designing Computer Agents With Personality To Improve Human-Machine Collaboration In Complex Systems, Sasanka V. Prabhala

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The dynamic nature of complex systems and the overwhelming amount of data that must be handled by human operators requires the development of smart systems that augment human capabilities. For these systems human-agent collaboration is part of the system dynamic. Unfortunately the computer agent is not typically perceived by the human operator as a collaborative team member. This research addressed the key question of how to develop and evaluate computer agents with personality to enhance human-machine collaboration. To move towards this goal three research objectives were established: (1) develop agents with personality, (2) validate that humans perceive these agents as …