Digital Commons Network^™

Evaluation Of Longwall Face Support Hydraulic Supply Systems, Ted M. Klemetti Ii

Graduate Theses, Dissertations, and Problem Reports (ETD)

With increases in panel size and production levels in longwall mining, the hydraulic flow rates required to allow the shields to keep pace with the mining operations have substantially increased. The panel size and production increases have also increased the hydraulic supply system's pressure losses. To quantitatively evaluate the possible design changes to the hydraulic supply system, a practical and accurate method of evaluating potential hydraulic supply systems for the shields is needed. This thesis endeavors to develop a method to evaluate the effects on pressure and flow rate from changes in a hydraulic supply system and to determine the …

Image Segmentation For Biometric Identification Systems, Eyad Haj Said

Graduate Theses, Dissertations, and Problem Reports (ETD)

Automating the identification process of individuals is receiving increased attention. Fully automated image segmentation from different types of biometric images is an essential step for designing automated identification systems. In this work, we address the problem of fully automated image segmentation in the context of dental and ear biometrics. We also address the problem of evaluating the quality of segmented image by designing an automated segmentation evaluator.;For image segmentation, we first apply a mathematical morphology operator to highlight the desired objects and suppress the others, and then threshold the resulting image to separate the desired objects from the background. We …

Multiagent Approach For Power System Reconfiguration, Pinak Tulpule

Graduate Theses, Dissertations, and Problem Reports (ETD)

The objective of this thesis is to develop an agent based reconfiguration algorithm for power system application with termination detection and to provide communication architecture for these agents. The underlying maximum flow algorithm based on graph theory has proven the concept of autonomous distributed reconfiguration using multiagent systems. The new rule-based algorithm takes into account the requirement of bidirectional power flows, and special power routing for DC devices. Even though the algorithm is self-stabilizing and agents become idle after finite time, implementation of the solution within the actual power system requires that all agents be in an idle state. The …

Interaction Between Metal Fission Products And Triso Coating Materials, Clemens Heske

Fuels Campaign (TRP)

This project focuses on the chemical bonding and interface formation of metal fission products with the coating materials used in tri-isotropic (TRISO) fuel particles for gas-cooled reactors. By combining surface- and bulk-sensitive spectroscopic methods, intermediate chemical phases at the interface, intermixing/ diffusion behavior, and the electronic interface structure as a function of material (metal and coating materials) and temperature are examined.

In the past year, emphasis was placed on a detailed analysis and description of the Cs/SiC interface formation process.

Reactor Physics Studies For The Afci Reactor-Accelerator Coupling Experiments Project, Denis Beller

Transmutation Sciences Physics (TRP)

The specific research objective of this three-year project is to design and conduct accelerator driven experiments, which will help demonstrate in the U.S. the ability to design, compute, and conduct ADSS experiments and to predict and measure source importance, coupling efficiency, sub-critical reactor kinetics and source-driven transients. In addition, databases will be created for both steady state and transient ADSS experiments for the nuclear community to develop and test new computational codes and methods, and the importance of a driving neutron source in various regions of different subcritical assemblies will be mapped. Experiments will be conducted and compared to calculations …

Criticality Studies For Urex Processes, Denis Beller

Separations Campaign (TRP)

The completion of criticality experiments for mixtures of transuranic actinides (TRU–includes Np, Pu, Am, and Cm) that will be created during the separation of used nuclear fuel may be a requirement in order to construct prototype plants for the Global Nuclear Energy Partnership. In this program and the Advanced Fuel Cycle Research and Development (AFC R&D) program that supports it, economic and environmental methods are being developed to reduce the impact of waste from commercial nuclear fuel cycles.

Recycling of used fuel by chemically separating it into U, fission products, and TRU would be the first step in this new …

Content-Based Video Classification And Comparison, John Alexander Bunch

UNLV Retrospective Theses & Dissertations

Automatic video analysis tools have dramatically increased in importance as the Internet video revolution has blossomed. This thesis presents an approach for automatic comparison of videos based on the inherent content. Also, an approach for creating groups (or clusters) of similar videos from a large video database is given; First, methods simplifying and summarizing the content of videos will be presented. Such methods include shot boundary detection and key frame feature extraction; Next, a comparison of different distance measures between videos will be given. These distance measures will be used to construct video clusters, and results will be compared.

T-Theory And Analysis Of Online Algorithms, James Oravec

UNLV Retrospective Theses & Dissertations

Several advancements in Online Algorithms can be credited to T-theory, a field of discrete mathematics. T-theory has aided in the development of several online algorithms for the k-server problem, although the standard notation of T-theory was not used at the time of their creation; A summary of the k-server problem, and some important concepts of T-theory, are given. A number of known k-server results are restated using the established terminology of T-theory. Included is a 3-competitiveness proof, using T-theory, for the HARMONIC algorithm for two servers, which was presented in a paper by Larmore and Oravec [71]; Previously, the Knowledge …

A Diffusion Model Of Lightning Radiative Transfer Using Cylindrical Geometry, Rina Alfonso Santos

UNLV Retrospective Theses & Dissertations

Clouds come in different shapes and sizes and are made up of different constituents. Realistic clouds are composed of heterogeneous distribution of constituents (ice particle, needle shaped objects, cubic, hexagonal, etc.). For tractability of solutions and smoothness of calculations, assumptions are made. The assumption is viable due to multiple scattering effect for propagation of radiation in random media. In Koshak et al. (1994), "Diffusion Model for Lightning Radiative Transfer", the cloud was treated as a nuclear reactor in order to obtain forms that can be readily computable and a simple geometry was chosen, i.e., a homogeneous rectangular parallelepiped Cloud In …

Tensile Deformation, Toughness And Crack Propagation Studies Of Alloy 617, Vikram Marthandam

UNLV Retrospective Theses & Dissertations

Austenitic nickel-base Alloy 617 has been tested under tensile loading at temperatures relevant to both the Nuclear Hydrogen Initiative and the Next Generation Nuclear Plant programs of the U.S. Department of Energy. Two important metallurgical phenomena, namely dynamic strain aging (DSA) and yield strength anomaly (YSA), have been identified based on the resultant data. DSA was characterized by reduced plastic strain and serrations in the engineering stress versus engineering strain diagrams. YSA was manifested by enhanced yield strength at relatively higher temperatures. A mechanistic understanding of DSA and YSA phenomena has been developed based on the estimation of dislocation density, …

Journal Of Mathematics And Science: Collaborative Explorations

Journal of Mathematics and Science: Collaborative Explorations

No abstract provided.

The Clep Program: An Evaluation And Assessment At A Small Private University, William Beaver, Stephen T. Paul

Mid-Western Educational Researcher

The Educational Testing Service (ETS) created the College Level Examination Program (CLEP) in 1965 and over the years it has become a staple of American higher education. In order to better understand the ramifications of the CLEP program, this article provides a brief history of CLEP and reexamines some of the findings of earlier research. The present study investigates new areas by addressing several research questions. For instance, what are the impacts of a student’s age, academic ability, gender, and previous learning experiences in regard to passing a CLEP exam? How much time do students spend in preparing for CLEP, …

Two-Phase Flow Chromatography Based On Gas-Liquid Phase Diagrams, Siyuan Hou

Electronic Theses and Dissertations

No abstract provided.

High-Speed Low-Voltage Cmos Flash Analog-To-Digital Converter For Wideband Communication System-On-A-Chip, Mingzhen Wang

Browse all Theses and Dissertations

With higher-level integration driven by increasingly complex digital systems and downscaling CMOS processes available, system-on-a-chip (SoC) is an emerging technology of low power, high cost effectiveness and high reliability and is exceedingly attractive for applications in high-speed data conversion wireless and wideband communication systems. This research presents a novel ADC comparator design methodology; the speed and performance of which is not restricted by the supply voltage reduction and device linearity deterioration in scaling-down CMOS processes. By developing a dynamic offset suppression technique and a circuit optimization method, the comparator can achieve a 3 dB frequency of 2 GHz in 130 …

Classification Of Microarray Data To Predict Toxic Exposure, Tarek A. Seleem

Browse all Theses and Dissertations

This thesis presents a software system for the analysis of microarray data. Microarrays are a relatively new technology that can be used to examine the state of the genome of an organism at some instant in time. The challenge is the amount of natural variation in biological systems limits our ability to identify specific genes that may be sensitive to changes in an organism's physiology or its environment. The analysis software consists of three modules. The first module filters microarray data to reduce the complexity of the problem. The second module selects subsets of genes for evaluation using a genetic …

Biogeochemical Processes And Seasonal Effects In Flow-Through Mesocosm Reactors Simulating Constructed Wetlands, Sarah J. Tritschler

Browse all Theses and Dissertations

Due to their distinctive environments, constructed wetlands are utilized to remediate groundwater that has been contaminated with chlorinated ethenes (i.e. perchloroethene) and other such contaminants. This research focuses on vertical flow mesocosm reactors housed in a greenhouse at Wright State University, which simulate a constructed wetland on Wright-Patterson Air Force Base. These reactors were studied to investigate the effects of vegetation and seasonal changes on the redox parameters present. Water samples were collected from six different reactors from late September/early October 2006 until August 2007. The reactors were sampled three days in a row and this sampling was done once …

Investigation Of The Reflective Properties Of A Left-Handed Metamaterial, Amanda Durham

Browse all Theses and Dissertations

The purpose of this project is to investigate the reflective properties of a left-handed metamaterial (LHM) through the use of a finite element analysis software called FEMLAB. In the 1960's, V. Veselago theorized that a material with negative permeability and negative permittivity has a negative index of refraction. In 2000, such a metamaterial was built and demonstrated at microwave frequencies. Previous work had focused on the transmission properties of the metamaterial. In our work, the reflected wave was examined for a LHM subject to an incident transverse electric wave. The different generalizations, first proposed by Veselago, of the Fresnel and …

The Electroanalytical Performance Of Sonogel Carbon Titanium (Iv) Oxide Electrodes Versus Conducting Polymer Electrodes In The Electrochemical Detection Of Biological Molecules, Jelynn A. Stinson

Browse all Theses and Dissertations

The electrochemical performance of a newly developed sonogel carbon titanium (IV) oxide (SGC/TiO2 ) electrode against poly(3-methylthiophene) (P3MT) and poly(2,2'-bithiophene) (PBTP) modified electrodes in the electrochemical detection of biological molecules is reported. The stability of the Titanium (IV) Oxide coating on the sonogel carbon electrode was shown to be greater than the P3MT coating on the conventional size glassy carbon electrode. After 10 consecutive scans, there was a 21% loss of the initial signal at the P3MT modified electrode and a 5% loss of the initial signal at the SGC/TiO2 electrode. The influence of NAD+ on NADH response was tested. …

Laser Initiated Chain Reactions: The Kinetics Of The Chlorine/Cyclohexane/Oxygen Chain System, Robert Alan Forlines

Browse all Theses and Dissertations

The combination of laser photolysis with infrared chemiluminescence detection has proven an effective technique for determining the propagation rate coefficients of halogen + RH chain reactions. This thesis will extend the technique to cyclic alkanes by determining the propagation rate coefficients of the Cl₂/ cyclohexane chain system as well as the rate coefficient for the primary chain termination mechanism, R + O₂ → RO₂. The following reaction scheme is supported by the kinetic analysis: Cl₂ → 2Cl Laser Photolysis Cl + RH → HCl(v) + R First Propagation Step (k₁) R + …

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 …

Experimental And Computational Studies Of Temperature Gradient Driven Molecular Transport In Gas Flows Through Nano/Micro-Scale Channels, Yen-Lin Han, Alina A. Alexeenko, Marcus Young, Eric Phillip Muntz

School of Aeronautics and Astronautics Faculty Publications

Studies at the University of Southern California have shown that an unconventional solid-state device, the Knudsen Compressor, can be operated as a micro-scale pump or compressor. The critical components of Knudsen Compressors are gas transport membranes, which can be formed from porous materials or densely packed parallel arrays of channels. An applied temperature gradient across a transport membrane creates a thermal creep pumping action. Experimental and computational techniques that have been developed for the investigations will be discussed. Experimental studies of membranes formed from machined aerogels, activated by radiant heating, have been used to investigate thermal creep flows. In computational …

Decision Aid For Electronic Simulation In Construction, Purdue Ect Team

ECT Fact Sheets Archive

The Decision Aid for Electronic Simulation in Construction is an output of the research “Electronic Simulation in Construction” sponsored by CII (Construction Industry Institute). The Web-based Decision Aid was developed to assist a decision-maker in utilizing the results of this research. This system along with the database allows the user to (i) establish the need for electronic simulation, (ii) ascertain specific needs with respect to application domain, product features, and operating system requirements, and (iii) identify products and suppliers that support the need and requirements established in the previous steps.

Natural Focusing Of X Rays From Ferroelectric Lithium Niobate Wafers, S. Durbin, T. Jach, S. Kim, V. Gopalan

Department of Physics and Astronomy Faculty Publications

The interaction of waves with inhomogeneous media leads to the natural focusing of light, the channelling of waves into stable caustics. We have extended natural focusing to x rays, observing caustics in topographs of ferroelectric lithium niobate. Voltage across domains of reversed polarity induces perturbations to the local crystal planes, producing dramatic variations in the images. Ray tracing shows a "catastrophic" discontinuity, causing bright focal lines. Analysis reveals details of boundary strains and local ferroelectric properties. Controlled focusing could be extended to designed domain patterns to probe microstructural properties, and also to a type of voltage-controlled ferroelectric optics for x …

Smart Sewer Assessment Systems, Purdue Ect Team

ECT Fact Sheets Archive

The need for accurate preventive assessment of sewer conditions is increasing world wide. The new method utilizes qualified inspection systems that are automated and that utilize artificial intelligence to assess whether or not a crack in the surface of the pipe exists. The KARO system is one example. Developed by the German Federal Ministry of Education, Science, Research, and Technology (BMBF) and four partners from both industry and research institutions. This system is composed of a mobile control and surveillance station, and a mobile robot.

Stroboscope, Purdue Ect Team

ECT Fact Sheets Archive

STROBOSCOPE is an acronym for STate and Resource Based Simulation of COnstructionProcEsses. It is a general-purpose simulation programming language that has been designed for the simulation of very complex construction processes that involve many different types of resources. STROBOSCOPE models are based on a network of interconnected modeling elements and on a series of programming statements that give the elements unique behavior and control the simulation.

Analysis Of Solid-Liquid Phase Change Under Pulsed Heating, S. Krishnan, J. Y. Murthy, S V. Garimella

CTRC Research Publications

Solid/liquid phase change occurring in a rectangular container with and without metal foams subjected to periodic pulsed heating is investigated. Natural convection in the melt is considered. Volume-averaged mass and momentum equations are employed, with the Brinkman–Forchheimer extension to Darcy’s law used to model the porous resistance. A local thermal nonequilibrium model, assuming equilibrium melting at the pore scale, is employed for energy transport through the metal foams and the interstitial phase change material (PCM). Separate volumeaveraged energy equations for the foam and the PCM are written and are closed using a heat transfer coefficient. The enthalpy method is employed …

Numerical And Experimental Investigation Of Solidification Shrinkage, D. Sun, S V. Garimella

CTRC Research Publications

The solidification heat transfer, melt convection, and volume shrinkage in the casting of an energetic material are analyzed through numerical modeling and experimental investigation. The shrinkage resulting from phase change is considered through the volume-of-fluid method. The model is validated against an analytical solution and then applied to study the volume contraction during the casting of trinitrotoluene (TNT). Good agreement is obtained between experimental results and predictions of temperatures at selected locations as well as shrinkage shape. New casting conditions are suggested based on the analysis, and improved results are observed both numerically and experimentally.

Correlation Energy In A Spin-Polarized Two-Dimensional Electron Liquid In The High-Density Limit, S. Chesi, G. F. Giuliani

Department of Physics and Astronomy Faculty Publications

We have obtained an analytic expression for the ring diagram contribution to the correlation energy of a two-dimensional electron liquid as a function of the uniform fractional spin polarization. Our results can be used to improve the interpolation formulas which represent the basic ingredient for the construction of modern spin-density functionals in two dimensions.

Single Spike Solutions For Strings On S-2 And S-3, R. Ishizeki, M. Kruczenski

Department of Physics and Astronomy Faculty Publications

We study solutions for rigidly rotating strings on a two-sphere. Among them we find two limiting cases that have a particular interest, one is the already known giant magnon and the other we call the single spike solution. The limiting behavior of this last solution is a string infinitely wrapped around the equator. It differs from that solution by the existence of a single spike of height (theta) over bar that points toward the north pole. We study its properties and compute its energy E and angular momentum J as a function of (theta) over bar. We further generalize the …

Bond-Propagation Algorithm For Thermodynamic Functions In General Two-Dimensional Ising Models, Y. L. Loh, E. W. Carlson, M. Y. J. Tan

Department of Physics and Astronomy Faculty Publications

Recently, we developed and implemented the bond-propagation algorithm for calculating the partition function and correlation functions of random-bond Ising models in two dimensions [Y. L. Loh and E. W. Carlson, Phys. Rev. Lett. 97, 227205 (2006)]. The algorithm is the fastest available for calculating these quantities near the percolation threshold. In this paper, we show how to extend the bond-propagation algorithm to directly calculate thermodynamic functions by applying the algorithm to derivatives of the partition function and we derive explicit expressions for this transformation. We also discuss variations of the original bond-propagation procedure within the larger context of Y del …