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Electromagnetic methods for measuring materials properties of cylindrical rods and array probes for rapid flaw inspection

Description: The case-hardening process modifies the near-surface permeability and conductivity of steel, as can be observed through changes in alternating current potential drop (ACPD) along a rod. In order to evaluate case depth of case hardened steel rods, analytical expressions are derived for the alternating current potential drop on the surface of a homogeneous rod, a two-layered and a three-layered rod. The case-hardened rod is first modeled by a two-layer rod that has a homogeneous substrate with a … more
Date: May 1, 2005
Creator: Sun, Haiyan
Partner: UNT Libraries Government Documents Department
open access

High-resolution flurescence spectroscopy in immunoanalysis

Description: The work presented in this dissertation combines highly sensitive and selective fluorescence line-narrowing spectroscopy (FLNS) detection with various modes of immunoanalytical techniques. It has been shown that FLNS is capable of directly probing molecules immunocomplexed with antibodies, eliminating analytical ambiguities that may arise from interferences that accompany traditional immunochemical techniques. Moreover, the utilization of highly cross-reactive antibodies for highly specific ana… more
Date: May 1, 2005
Creator: Grubor, Nenad M.
Partner: UNT Libraries Government Documents Department
open access

Structural studies of two novel La-Sn compounds: La30Sn30 and La32Ni2Sn35

Description: Two novel intermetallic compounds containing lanthanum and tin have been obtained for the first time. Single crystal structures of these two phases, La{sub 30}Sn{sub 30} and La{sub 32}Ni{sub 2}Sn{sub 35} have been studied by X-ray crystallography. La{sub 30}Sn{sub 30} is a new 1:1 binary containing La and Sn and has been refined in the Cmmm space group. This phase was made at high temperatures (<1200 C) from a loaded composition of La{sub 68}Sn{sub 70}. Unlike the reported 1:1 binary, LaSn w… more
Date: May 1, 2005
Creator: Yang, Amie S.
Partner: UNT Libraries Government Documents Department
open access

Rumpling phenomenon in platinum modified Ni-Al alloys

Description: Surface undulations known as rumpling have been shown to develop at the surface of bond coats used in advanced thermal barrier coating systems. Rumpling can result in cracking and eventual spallation of the top coat. Many mechanisms to explain rumpling have been proposed, and among them is a martensitic transformation. High-temperature x-ray diffraction, differential scanning calorimetry and potentiometry were used to investigate the nature of the martensitic transformation in bulk platinum-mod… more
Date: May 1, 2005
Creator: Zimmerman, Benjamin Joseph
Partner: UNT Libraries Government Documents Department
open access

Translation techniques for distributed-shared memory programming models

Description: The high performance computing community has experienced an explosive improvement in distributed-shared memory hardware. Driven by increasing real-world problem complexity, this explosion has ushered in vast numbers of new systems. Each new system presents new challenges to programmers and application developers. Part of the challenge is adapting to new architectures with new performance characteristics. Different vendors release systems with widely varying architectures that perform differentl… more
Date: August 1, 2005
Creator: Fuller, Douglas James
Partner: UNT Libraries Government Documents Department
open access

A texture-based framework for improving CFD data visualization in a virtual environment

Description: In the field of computational fluid dynamics (CFD) accurate representations of fluid phenomena can be simulated hut require large amounts of data to represent the flow domain. Most datasets generated from a CFD simulation can be coarse, {approx}10,000 nodes or cells, or very fine with node counts on the order of 1,000,000. A typical dataset solution can also contain multiple solutions for each node, pertaining to various properties of the flow at a particular node. Scalar properties such as den… more
Date: May 5, 2005
Creator: Bivins, Gerrick O'Ron
Partner: UNT Libraries Government Documents Department
open access

An improved multiscale model for dilute turbulent gas particle flows based on the equilibration of energy concept

Description: Many particle-laden flows in engineering applications involve turbulent gas flows. Modeling multiphase turbulent flows is an important research topic with applications in fluidized beds and particle conveying. A predictive multiphase turbulence model can help CFD codes to be more useful for engineering applications, such as the scale-up in the design of circulating fluidized combustor and coal gasifications. In engineering applications, the particle volume fraction can vary from dilute (<10{… more
Date: May 1, 2005
Creator: Xu, Ying
Partner: UNT Libraries Government Documents Department
open access

ATCOM: Automatically Tuned Collective Communication System for SMP Clusters

Description: Conventional implementations of collective communications are based on point-to-point communications, and their optimizations have been focused on efficiency of those communication algorithms. However, point-to-point communications are not the optimal choice for modern computing clusters of SMPs due to their two-level communication structure. In recent years, a few research efforts have investigated efficient collective communications for SMP clusters. This dissertation is focused on platform-i… more
Date: December 17, 2005
Creator: Wu, Meng-Shiou
Partner: UNT Libraries Government Documents Department
open access

Giant Magnetoresistive Sensors and Magnetic Labels for Chip-Scale Detection of Immunosorbent Assays

Description: The combination of giant magnetoresistive sensors, magnetic labeling strategies, and biomolecule detection is just beginning to be explored. New readout methods and assay formats are necessary for biomolecules detection to flourish. The work presented in this dissertation describes steps toward the creation of a novel detection method for bioassays utilizing giant magnetoresistive sensors as the readout method. The introduction section contains a brief review of some of the current methods of b… more
Date: December 17, 2005
Creator: Millen, Rachel Lora
Partner: UNT Libraries Government Documents Department
open access

Balancing a U-Shaped Assembly Line by Applying Nested Partitions Method

Description: In this study, we applied the Nested Partitions method to a U-line balancing problem and conducted experiments to evaluate the application. From the results, it is quite evident that the Nested Partitions method provided near optimal solutions (optimal in some cases). Besides, the execution time is quite short as compared to the Branch and Bound algorithm. However, for larger data sets, the algorithm took significantly longer times for execution. One of the reasons could be the way in which the… more
Date: December 17, 2005
Creator: Bhagwat, Nikhil V.
Partner: UNT Libraries Government Documents Department
open access

Electrochemically modulated liquid chromatography: Theoretical investigations and applications from the perspectives of chromatography and interfacial electrochemistry

Description: Electrochemically modulated liquid chromatography (EMLC) employs a conductive material as both a stationary phase for chromatographic separations and as a working electrode for performing electrochemistry experiments. This dual functionality gives EMLC the capacity to manipulate chromatographic separations by changing the potential applied (E{sub app}) to the stationary phase with respect to an external reference. The ability to monitor retention as a function of E{sub app} provides a means to … more
Date: May 1, 2005
Creator: Keller, David W.
Partner: UNT Libraries Government Documents Department
open access

Subunits of highly Fluorescent Protein R-Phycoerythrin as Probes for Cell Imaging and Single-Molecule Detection

Description: The purposes of our research were: (1) To characterize subunits of highly fluorescent protein R-Phycoerythrin (R-PE) and check their suitability for single-molecule detection (SMD) and cell imaging, (2) To extend the use of R-PE subunits through design of similar proteins that will be used as probes for microscopy and spectral imaging in a single cell, and (3) To demonstrate a high-throughput spectral imaging method that will rival spectral flow cytometry in the analysis of individual cells. We… more
Date: December 17, 2005
Creator: Isailovic, Dragan
Partner: UNT Libraries Government Documents Department
open access

Characterization of piesoelectric ZnO thin films and the fabrication of piezoelectric micro-cantilevers

Description: In Atomic Force Microscopy (AFM), a microcantilever is raster scanned across the surface of a sample in order to obtain a topographical image of the sample's surface. In a traditional, optical AFM, the sample rests on a bulk piezoelectric tube and a control loop is used to control the tip-sample separation by actuating the piezo-tube. This method has several disadvantages--the most noticeable one being that response time of the piezo-tube is rather long which leads to slow imaging speeds. One p… more
Date: August 1, 2005
Creator: Johnson, Raegan Lynn
Partner: UNT Libraries Government Documents Department
open access

Potential Release Site Sediment Concentrations Correlated to Storm Water Station Runoff through GIS Modeling

Description: This research examined the relationship between sediment sample data taken at Potential Release Sites (PRSs) and storm water samples taken at selected sites in and around Los Alamos National Laboratory (LANL). The PRSs had been evaluated for erosion potential and a matrix scoring system implemented. It was assumed that there would be a stronger relationship between the high erosion PRSs and the storm water samples. To establish the relationship, the research was broken into two areas. The first… more
Date: June 1, 2005
Creator: McLean, C.T.
Partner: UNT Libraries Government Documents Department
open access

Effects of Various Blowout Panel Configurations on the Structural Response of Los Alamos National Laboratory Building 16-340 to Internal Explosions

Description: Abstract: The risk of accidental detonation is present whenever any type of high explosives processing activity is performed. These activities are typically carried out indoors to protect processing equipment from the weather and to hide possibly secret processes from view. Often, highly strengthened reinforced concrete buildings are employed to house these activities. These buildings may incorporate several design features, including the use of lightweight frangible blowout panels, to help mit… more
Date: September 2005
Creator: Wilke, Jason P.; Pohs, Keith G. & Plumlee, Deidré A.
Partner: UNT Libraries Government Documents Department
open access

Direct measurement of anisotropy of interfacial free energy from grain boundary groove morphology in transparent organic metal analong systems

Description: Both academia and industry alike have paid close attention to the mechanisms of microstructural selection during the solidification process. The forces that give rise to and the principles which rule the natural selection of particular morphologies are important to understanding and controlling new microstructures. Interfacial properties play a very crucial role to the selection of such microstructure formation. In the solidification of a metallic alloy, the solid-liquid interface is highly mob… more
Date: August 1, 2005
Creator: Rustwick, Bryce A.
Partner: UNT Libraries Government Documents Department
open access

Global structual optimizations of surface systems with a genetic algorithm

Description: Global structural optimizations with a genetic algorithm were performed for atomic cluster and surface systems including aluminum atomic clusters, Si magic clusters on the Si(111) 7 x 7 surface, silicon high-index surfaces, and Ag-induced Si(111) reconstructions. First, the global structural optimizations of neutral aluminum clusters Al{sub n} (n up to 23) were performed using a genetic algorithm coupled with a tight-binding potential. Second, a genetic algorithm in combination with tight-bindi… more
Date: May 1, 2005
Creator: Chuang, Feng-Chuan
Partner: UNT Libraries Government Documents Department
open access

Real-time monitoring and manipulation of single bio-molecules in free solution

Description: The observation and manipulation of single biomolecules allow their dynamic behaviors to be studied to provide insight into molecular genetics, biochip assembly, biosensor design, DNA biophysics. In a PDMS/glass microchannel, a nonuniform electroosmotic flow (EOF) was created. By using a scanning confocal fluorescence microscope and total internal-reflection fluorescence microscope (TIRFM), we demonstrated that negatively charged DNA molecules were focused by the nonuniform EOF into a thin laye… more
Date: August 1, 2005
Creator: Li, Hung-Wing
Partner: UNT Libraries Government Documents Department
open access

Coordination of dibensothiophenes and corannulenes to organometallic ruthenium (II) fragments

Description: This dissertation contains five papers in the format required for journal publication which describe (in part) my research accomplishments as a graduate student at Iowa State University. This work can be broadly categorized as the binding of weakly-coordinating ligands to cationic organometallic ruthenium fragments, and consists of two main areas of study. Chapters 2-4 are investigations into factors that influence the binding of dibenzothiophenes to {l_brace}Cp'Ru(CO){sub 2}{r_brace}{sup +} fr… more
Date: May 1, 2005
Creator: Vecchi, Paul Anthony
Partner: UNT Libraries Government Documents Department
open access

Hiking the valleys of quatum chemistry

Description: This thesis is concerned with both the application and the extension of quantum chemical methods. Each chapter of the thesis represents a paper that has been published in or will be submitted to a scientific journal. The first three chapters of this thesis describe contributions made to chemistry through the use of quantum chemical methods, while the final two chapters illustrate the development of new methods. Chapter 2 and Chapter 3 characterize a study of the electronic structure and magneti… more
Date: August 1, 2005
Creator: Aikens, Christine Marie
Partner: UNT Libraries Government Documents Department
open access

Field-induced magnetic phase transitions and correlated electronic states in the hexagonal RAgGE and RPtIn series

Description: The present work was initially motivated by the desire to continue the study of complex metamagnetism in relation to the crystal structure of various compounds; this study already included tetragonal compounds like HoNi{sub 2}B{sub 2}C (Canfield 1997b; Kalatsky 1998) and DyAgSb{sub 2} (Myers 1999), in which the rare earths occupy unique tetragonal positions. We intended to find hexagonal systems suited for such a study, with complex metamagnetic properties, and the search for extremely anisotro… more
Date: August 1, 2005
Creator: Morosan, Emilia
Partner: UNT Libraries Government Documents Department
open access

The breakdown of de Gennes Scaling in TbxEr1-xNi2B2C and its mean field theory explanation

Description: The Neel temperatures, T{sub N}, of Tb{sub x}Er{sub 1-x}Ni{sub 2}B{sub 2}C samples have been determined from the temperature dependence of magnetization measurements. A breakdown of the de Gennes scaling of T{sub N} with a clear turning point around x = 0.45 has been observed. The T{sub N} values of Tb{sub x}Er{sub 1-x}Ni{sub 2}B{sub 2}C do not change much within the range of O < x < 0.45 and then, for larger x they increase almost linearly with concentration until T{sub N} = 14.9K is rea… more
Date: May 1, 2005
Creator: Gao, Chunwang
Partner: UNT Libraries Government Documents Department
open access

Tuning the Superconducting Properties of Magnesium Diboride

Description: This work is presented in the following order: A review of the relevant physics and discussion of theoretical predictions for a two gap superconducting compound is given in chapter 2. Chapter 3 provides a review of the basic properties of MgB{sub 2}. Details of sample synthesis and characterization are given in chapter 4. Chapter 5 presents normal state and superconducting properties of Mg(B{sub 1-x}C{sub x}){sub 2} wires. Attempts to increase critical current densities in filaments via titaniu… more
Date: December 17, 2005
Creator: Wilke, Rudeger Heinrich Theoderich
Partner: UNT Libraries Government Documents Department
open access

Reduction of Solvent Effect in Reverse Phase Gradient Elution LC-ICP-MS

Description: Quantification in liquid chromatography (LC) is becoming very important as more researchers are using LC, not as an analytical tool itself, but as a sample introduction system for other analytical instruments. The ability of LC instrumentation to quickly separate a wide variety of compounds makes it ideal for analysis of complex mixtures. For elemental speciation, LC is joined with inductively coupled plasma mass spectrometry (ICP-MS) to separate and detect metal-containing, organic compounds i… more
Date: December 17, 2005
Creator: Sullivan, Patrick Allen
Partner: UNT Libraries Government Documents Department
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