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 …

Integrated Modeling Of Nitrate Contamination Of Groundwater In Agriculture-Dominated Watersheds, M. Almasri, Jagath J. Kaluarachchi

Civil and Environmental Engineering Faculty Publications

This paper presents and implements a framework for modeling the impact of land use practices and protection alternatives on nitrate pollution of groundwater in agricultural watersheds. The framework utilizes the national land cover database (NLCD) of the United State Geological Survey (USGS) grid and a geographic information system (GIS) to account for the spatial distribution of on-ground nitrogen sources and corresponding loadings. The framework employs a soil nitrogen dynamic model to estimate nitrate leaching to groundwater. These estimates were used in developing a groundwater nitrate fate and transport model. The framework considers both point and non-point sources of nitrogen across …

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 On Heterogeneous Structure In Acceleration Regime Of Gas-Solid Riser Flows, Chao Zhu, Jun You, Dawei Wang, Liang-Shih Fan

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Recent measurement of solid concentration in gas-solid riser flows by Electric Capacitance Tomography (ECT) reveals a strong heterogeneous structure, typically represented by a core-annulus-wall zone pattern. In this paper we present a mechanistic model in which the formation of the heterogeneous structure is due to the radial migration of solid flow from the wall toward center as well as due to the non-uniform acceleration of solids across the cross-section near the bottom of the riser. Firstly we present the general governing equations and discuss problem closure; then a simplified model with one-way flow coupling between the wall region and the …

Modeling Fuel Mixing In A Fluidized Bed Combustor, David Pallarès, Filip Johnsson

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

This paper presents a 3-dimensional model for fuel mixing in fluidized bed combustors. The model accounts for the mixing patterns experimentally shown to govern the mixing in the different zones of the riser and the return leg and can be applied both under bubbling and circulating regimes. Thus, the semi-empirical basis of the model was previously validated in different large-scale fluidized bed combustors and is combined with a model for fuel particle conversion to obtain the fuel concentration. Results obtained with the model are compared with experimental data from the Chalmers 12 MWth CFB combustor, yielding reasonably agreement.

Modeling Of An Interconnected Fluidized Bed Reactor For Chemical Looping Combustion, Min Xu, Naoko Ellis, Ho-Jung Ryu , C. Jim Lim

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Chemical Looping Combustion (CLC) is comprised of two reactors, in which direct contact between air and fuel is avoided. A metal oxide, as oxygen carrier, transports oxygen from the air reactor to the fuel reactor while circulating between them. Based on the hydrodynamics coupled with reaction kinetics of oxygen carrier from the literature, a model for an interconnected fluidized bed reactor has been developed to optimize the design and operation of the reactor system. The model considers the chemical reaction of a single particle and a particle population balance for the calculation of bed particle conversion. The core-annulus and two-phase …

Simulation Of A Silicon Cvd Spouted Fluidized Bed Reactor: Semi-Batch Operations, Juliana Piña, Verónica Bucalá, Susana N. Schbib, Paul Ege, Hugo Ignacio De Lasa

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A comprehensive multiphase gas-solid mathematical model that successfully describes the batch growth of silicon particles in a chemical vapor deposition (CVD) submerged spouted bed reactor is extended to simulate semi-batch operations with periodic seeds additions and product extractions. This model takes into account the fluidized bed reactor as well as a population balance equation representing particle growth and agglomeration. Experimental data obtained from semi-batch operation in a pilot scale reactor at REC Silicon Inc. are used to evaluate the proposed mathematical model.

A Distributed Model Of Carbohydrate Transport And Metabolism In The Liver During Rest And High-Intensity Exercise, E Chalhoub, L. Xie, V. Balasubramanian, Joanne M. Belovich

Chemical & Biomedical Engineering Faculty Publications

A model of reaction and transport in the liver was developed that describes the metabolite concentration and reaction flux dynamics separately within the tissue and blood domains. The blood domain contains equations for convection, axial dispersion, and transport to the surrounding tissue; and the tissue domain consists of reactions representing key carbohydrate metabolic pathways. The model includes the metabolic heterogeneity of the liver by incorporating spatial variation of key enzymatic maximal activities. Simulation results of the overnight fasted, resting state agree closely with experimental values of overall glucose uptake and lactate output by the liver. The incorporation of zonation …

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 …

Neural Network And Regression Modeling Of Extrusion Processing Parameters And Properties Of Extrudates Containing Ddgs, Nehru Chevanan, Kasiviswanathan Muthukumarappan, Kurt A. Rosentrater

Kurt A. Rosentrater

Two sets of experiments using a single-screw extruder were conducted with an ingredient blend containing 40% DDGS (distillers dried grains with solubles), along with soy flour, corn flour, fish meal, vitamin mix, and mineral mix, with the net protein content adjusted to 28%. The variables controlled in the first experiment included seven levels of die size, three levels of moisture content, three levels of temperature gradient in the barrel, and one screw speed. The variables altered in the second experiment included three levels of moisture content, three levels of temperature gradient in the barrel, five levels of screw speed, and …

3d Laser Scanning & Modeling System, Purdue Ect Team

ECT Fact Sheets

Traditional methods of measuring and modeling the surface geometry of large, complex structures or sites that require engineering or survey-grade accuracy are often inaccurate, incomplete or expensive. Inaccurate or incomplete drawings and models often lead to costly construction errors or delays. A portable, auto-scanning laser and PC system that lets users economically obtain accurate, complete, and timely as-built geometry information for large structures and sites. The system can remotely measure natural surfaces up to 100m away at the speed of 800 points per second. With spacing between adjacent points as fine as 1mm, users can capture an extremely high level …

Resources: Student Friendly Modeling Materials, Todd R. Kelley, Jared Berrett

Publications

The article presents cost-effective materials for elementary classrooms that allow students to create models. These materials include card stock, clay, cable or zips ties, fasteners and bolts, and commercially manufactured building kits such as LEGOs, Erector Sets, Tinkertoys and K'Nex. In addition, the author asserts the importance of using such materials in promoting student learning of technology and engineering.

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 …

Validation Of Worst-Case And Statistical Models For An Automotive Emc Expert System, Daryl G. Beetner, Haixiao Weng, Meilin Wu, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Previous papers have presented algorithms for an EMC expert system used to predict potential electromagnetic compatibility problems in a vehicle early in the design process. Here, the accuracy of inductive and capacitive coupling algorithms are verified through representative measurements of crosstalk within an automobile. Worst-case estimates used by the algorithms are compared to measured values and are compared to values estimated using statistical methods. The worst-case algorithms performed well up to 10-20 MHz, but overestimated measured results by several dB in some cases and up to 10-15 dB in others. An approximate statistical variation of the current expert system algorithms …

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

Browse all Theses and Dissertations

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

Browse all Theses and Dissertations

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 …