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A linear, time-varying simulation of the respiratory tract system

Description: These results show that regional deposition efficiencies of inhaled particles are highly dependent on the level of physical activity in all the spectrum of thermodynamic and aerodynamic aerosol particle sizes; also it was shown that for particles in the aerodynamic size range, the values of regional deposition efficiencies at the inner regions of the lung are highly dependent on age. In addition, the shape of regional deposition efficiency curves as a function of particle size have a similar be… more
Date: November 1, 1992
Creator: Hernandez, O.
Partner: UNT Libraries Government Documents Department
open access

A quasi-static polynomial nodal method for nuclear reactor analysis

Description: Modern nodal methods are currently available which can accurately and efficiently solve the static and transient neutron diffusion equations. Most of the methods, however, are limited to two energy groups for practical application. The objective of this research is the development of a static and transient, multidimensional nodal method which allows more than two energy groups and uses a non-linear iterative method for efficient solution of the nodal equations. For both the static and transient… more
Date: September 1, 1992
Creator: Gehin, Jess C.
Partner: UNT Libraries Government Documents Department
open access

An analysis of monojet data in p{bar p} collisions at {radical}s = 1.8 TEV

Description: An analysis is presented of events with a single jet and significant missing transverse energy selected from 4.7 pb{sup {minus}1} of data collected at the Fermilab Tevatron with the CDF detector. The goal is to identify events of the type p{bar p} {yields} Z{sup 0} + jet; Z{sup 0} {yields} {nu}{bar {nu}}. Event selection and backgrounds are discussed. The number of observed monojet events is compared to the number of observed Z{sup 0} {yields} e{sup +}{sup {minus}} events in which the Z{sup 0} … more
Date: December 31, 1992
Creator: Markeloff, R.
Partner: UNT Libraries Government Documents Department
open access

A correlation between soil descriptions and {sup 226}Ra concentrations in Florida soils

Description: The soil radium content in Florida is highly variable. The range in radium concentrations, where the samples involved in this study are concerned, is from 0.1 pCi/g to 18.5 pCi/g. Low {sup 226}Ra concentrations (0.1 to 5 pCi/g) are evidenced in sands, moderate concentrations (5 to 11 pCi/g) are found in silt and gravel, and high {sup 226}Ra concentrations (>11 pCi/g) are found in soil horizons with shell, clay, and strata with phosphate. Strata containing phosphate yields a high concentration o… more
Date: December 31, 1992
Creator: Harrison, D. P.
Partner: UNT Libraries Government Documents Department
open access

Growth and characterization of isotopically enriched {sup 70}Ge and {sup 74}Ge single crystals

Description: Isotopically enriched {sup 70}Ge and {sup 74}Ge single crystals were successfully gown by a newly developed vertical Bridgman method. The system allows us to reliably grow high purity Ge single crystals of approximately 1 cm{sup 3} volume. To our knowledge, we have grown the first {sup 70}Ge single crystal. The electrically active chemical impurity concentration for both crystals was found to be {approximately}2 {times} cm{sup {minus}3} which is two order of magnitude better that of {sup 74}Ge … more
Date: October 1, 1992
Creator: Itoh, Kohei
Partner: UNT Libraries Government Documents Department
open access

High resolution photoelectron spectroscopy and femtosecond intramolecular dynamics using supersonic molecular beams

Description: High resolution He I{alpha} photoelectron spectroscopy of formaldehyde and ketene and their deuterated compounds, are reported. The combination of a (H2CO) double-pass high-resolution electron-energy analyzer and effective rotational cooling of the sample by supersonic expansion enable the spectroscopy of these molecular cations. The vibrational autocorrelation functions are calculated from the high-resolution photoelectron spectra, shedding light on the ultrafast intramolecular dynamics of the… more
Date: September 1, 1992
Creator: Niu, B.
Partner: UNT Libraries Government Documents Department
open access

A study of a tissue equivalent gelatine based tissue substitute

Description: A study of several tissue substitutes for use as volumetric dosimeters was performed. The tissue substitutes studied included tissue substitutes from previous studies and from ICRU 44. The substitutes were evaluated for an overall match to Reference Man which was used as a basis for this study. The evaluation was based on the electron stopping power, the mass attenuation coefficient, the electron density, and the specific gravity. The tissue substitute chosen also had to be capable of changing … more
Date: November 1, 1992
Creator: Spence, J. L.
Partner: UNT Libraries Government Documents Department
open access

A Klein-Gordon acoustic theory

Description: Geophysicists do not associate traveltime variation with density variation in acoustic or elastic wavefield interpretation. Rather, given a constant index of refraction, density variation within the medium of propagation is associated only with amplitudes. This point of view prevails because density does not occur as a variable in classical results such as Snell`s Law or the eikonal equation. Nevertheless, in this paper I predict, analytically, a continuum of density effects on acoustic wavefie… more
Date: December 1992
Creator: Anno, P. D.
Partner: UNT Libraries Government Documents Department
open access

Structural studies of molecular and metallic overlayers using angle- resolved photoemission extended fine structure

Description: Angle-resolved photoemission extended fine structure (ARPEFS) was used to study molecular and metallic overlayers on metal surfaces through analysis of p2mg(2{times}1)CO/Ni(110) and the p(2{times}2)K/Ni(111) adsorption. For the dense p2mg(2{times}1)CO/Ni(110) surface layer, photoemission intensities from C 1s level were measured in three directions at photoelectron kinetic energies 60-400 eV. Using multiple-scattering spherical-wave (MSSW) modeling, it was found that CO molecules are adsorbed o… more
Date: October 1, 1992
Creator: Huang, Z.
Partner: UNT Libraries Government Documents Department
open access

Perturbation theory in light-cone quantization

Description: A thorough investigation of light-cone properties which are characteristic for higher dimensions is very important. The easiest way of addressing these issues is by analyzing the perturbative structure of light-cone field theories first. Perturbative studies cannot be substituted for an analysis of problems related to a nonperturbative approach. However, in order to lay down groundwork for upcoming nonperturbative studies, it is indispensable to validate the renormalization methods at the pertu… more
Date: January 1, 1992
Creator: Langnau, A.
Partner: UNT Libraries Government Documents Department
open access

Lattice gaugefixing and other optics in lattice gauge theory

Description: We present results from four projects. In the first, quark and gluon propagators and effective masses and {Delta}I = 1/2 Rule operator matching coefficients are computed numerically in gaugefixed lattice QCD. In the second, the same quantities are evaluated analytically in the strong coupling, N {yields} {infinity} limit. In the third project, the Schwinger model is studied in covariant gauges, where we show that the effective electron mass varies with the gauge parameter and that longitudinal … more
Date: June 1, 1992
Creator: Yee, Ken
Partner: UNT Libraries Government Documents Department
open access

The effect of rhenium, sulfur and alumina on the conversion of hydrocarbons over platinum single crystals: Surface science and catalytic studies

Description: Conversion reactions of hydrocarbons over Pt-Re model catalyst surfaces modified by sulfur and alumina have been studied. A plasma deposition source has been developed to deposit Pt, Re, and Al on metal substrates variable coverage in ultrahigh vacuum without excessive heating. Conversion of n-hexane was performed over the Re-covered Pt and Pt-covered Re surfaces. The presence of the second metal increased hydrogenolysis activity of both Pt-Re surfaces. Addition of sulfur on the model Catalyst … more
Date: April 1, 1992
Creator: Kim, C.
Partner: UNT Libraries Government Documents Department
open access

A High Current, Short Pulse Electron Source for Wakefield Accelerators

Description: Design studies for the generation of a high current, short pulse electron source for the Argonne Wakefield Accelerator are presented. An L-band laser photocathode rf gun cavity is designed using the computer code URMEL to maximize the electric field on the cathode surface for fixed frequency and rf input power. A new technique using a curved incoming laser wavefront to minimize the space charge effect near the photocathode is studied. A preaccelerator with large iris to minimize wakefield effec… more
Date: 1992
Creator: Ho, Ching-Hung
Partner: UNT Libraries Government Documents Department
open access

Electrostatic turbulence and transport in the RFP edge

Description: This thesis details measurements of electrostatic turbulence and transport in the Madison Symmetric Torus reversed field pinch. The electrostatic fluctuation levels are found to be large, with {tilde n}{sub e}/n{sub e} {approximately} 30%--55% and {tilde T}{sub e}/T{sub e} {approximately} 15%--40%. The frequency and wavenumber spectra are broad, with {Delta}n {approximately} 70--150 and {Delta}m {approximately} 3--6, and differ from measured magnetic fluctuation spectra. The transport inferred … more
Date: May 1, 1992
Creator: Spragins, C. W.
Partner: UNT Libraries Government Documents Department
open access

Oxidation behavior in reaction-bonded aluminum-silicon alloy/alumina powder compacts

Description: Goal of this research is to determine the feasibility of producing low-shrinkage mullite/alumina composites by applying the reaction-bonded alumina (RBAO) process to an aluminum-silicon alloy/alumina system. Mirostructural and compositional changes during heat treatment were studied by removing samples from the furnace at different steps in the heating schedule and then using optical and scanning electron microscopy, EDS and XRD to characterize the powder compacts. Results suggest that the oxid… more
Date: December 1, 1992
Creator: Yokota, S. H.
Partner: UNT Libraries Government Documents Department
open access

Understanding conformal field theory through parafermions and Chern Simons theory

Description: Conformal field theories comprise a vast class of exactly solvable two dimensional quantum field theories. Conformal theories with an enlarged symmetry group, the current algebra symmetry, axe a key ingredient to possible string compactification models. The following work explores a Lagrangian approach to these theories. In the first part of this thesis, a large class of conformal theories, the so-called coset models, are derived semi-classically from a gauged version Of the Wess-Zumino-Witten … more
Date: November 19, 1992
Creator: Hotes, S. A.
Partner: UNT Libraries Government Documents Department
open access

Superconducting submillimeter and millimeter wave detectors

Description: The series of projects described in this dissertation was stimulated by the discovery of high temperature superconductivity. Our goal was to develop useful applications which would be competitive with the current state of technology. The high-{Tc} microbolometer was developed into the most sensitive direct detector of millimeter waves, when operated at liquid nitrogen temperatures. The thermal boundary resistance of thin YBa{sub 2}Cu{sub 3}0{sub 7-{delta}} films was subsequently measured and pr… more
Date: October 20, 1992
Creator: Nahum, M.
Partner: UNT Libraries Government Documents Department
open access

Edge gradient and safety factor effects on electrostatic turbulent transport in tokamaks

Description: Electrostatic turbulence and transport measurements are performed on the Tokapole-II tokamak at the University of Wisconsin-Madison, as the safety-factor and the edge equilibrium gradients and varied substantially. Tokapole-II is a poloidal divertor tokamak capable of operating at a wide range of safety factors due to its unique magnetic limiter configuration. It also has retractable material limiters in a large scrape-off region, which permits the study of edge boundary conditions like density… more
Date: May 1, 1992
Creator: Tan, Ing Hwie
Partner: UNT Libraries Government Documents Department
open access

Reaction and reorientation of electronically excited H{sub 2}(B)

Description: The room temperature rate (TR) constants for fluorescence quenching fluorescence of H{sub 2}, HD, and D{sub 2} B {sup 1}{Sigma}{sub u}{sup +} by {sup 4}He were measured as a function of the initially excited rotational and vibrational level of the hydrogen molecule, and the RT rate constants for molecular angular momentum reorientation of H{sub 2}, HD and D{sub 2} (B {sup 1}{Sigma}{sub u}{sup +}. v{prime}=0, J{prime}=1, M{sub J}=0) in collisions with He, Ne, Ar and H{sub 2}(X {sup 1}{Sigma}{sub… more
Date: September 1, 1992
Creator: Pibel, C. D.
Partner: UNT Libraries Government Documents Department
open access

Carotenoid biosynthesis in bacteria: In vitro studies of a crt/bch transcription factor from Rhodobacter capsulatus and carotenoid enzymes from Erwinia herbicola

Description: A putative transcription factor in Rhodobactor capsulatus which binds upstream of the crt and bch pigment biosynthesis operons and appears to play a role in the adaptation of the organism from the aerobic to the anaerobic-photosynthetic growth mode was characterized. Chapter 2 describes the identification of this factor through an in vitro mobility shift assay, as well as the determination of its binding properties and sequence specificity. Chapter 3 focuses on the isolation of this factor. Bio… more
Date: November 1, 1992
Creator: O`Brien, D. A.
Partner: UNT Libraries Government Documents Department
open access

Use of ligand-modified micellar-enhanced ultrafiltration to selectively separate copper ions from wastewater streams

Description: The selective removal of target ions from an aqueous solution containing ions of like charge by ligand-modified micellar-enhanced ultrafiltration (LM-MEUF), is presented. In LM-MEUF, surfactant and specially tailored ligand are added to the contaminated stream. The surfactant forms aggregates called micelles, the hydrocarbon core of which the ligand complexed with the target species will solubilize. The surfactant is chosen to have the same charge type as the target ion; therefore, other ions (… more
Date: December 31, 1992
Creator: Shadizadeh, S. B.
Partner: UNT Libraries Government Documents Department
open access

Encapsulation of Hazardous Wastes Into Agglomerates

Description: The objective of this study was to investigate the feasibility of using the cementitious properties and agglomeration characteristics of coal conversion byproducts to encapsulate and immobilize hazardous waste materials. The intention was to establish an economical way of co-utilization and co-disposal of wastes. In addition, it may aid in the eradication of air pollution problems associated with the fine-powdery nature of fly ash. Encapsulation into agglomerates is a novel approach of treating… more
Date: January 28, 1992
Creator: Guloy, Aida
Partner: UNT Libraries Government Documents Department
open access

A comparative evaluation of conceptual models for the Snake River Plain aquifer at the Idaho Chemical Processing Plant, INEL

Description: Geologic and hydrologic data collected by the United States Geological Survey (USGS) are used to evaluate the existing ground water monitoring well network completed in the upper portion of the Snake River Plain aquifer (SRPA) beneath the Idaho Chemical Processing Plant (ICPP). The USGS data analyzed and compared in this study include: (a) lithologic, geophysical, and stratigraphic information, including the conceptual geologic models intrawell, ground water flow measurement (Tracejector tests)… more
Date: January 1, 1992
Creator: Prahl, C. J.
Partner: UNT Libraries Government Documents Department
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