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Open cycle thermoacoustics

Description: A new type of thermodynamic device combining a thermodynamic cycle with the externally applied steady flow of an open thermodynamic process is discussed and experimentally demonstrated. The gas flowing through this device can be heated or cooled in a series of semi-open cyclic steps. The combination of open and cyclic flows makes possible the elimination of some or all of the heat exchangers (with their associated irreversibility). Heat is directly exchanged with the process fluid as it flows t… more
Date: January 1, 2000
Creator: Reid, Robert Stowers
Partner: UNT Libraries Government Documents Department
open access

Electron-capture delayed fission properties of neutron-deficient einsteinium nuclei

Description: Electron-capture delayed fission (ECDF) properties of neutron-deficient einsteinium isotopes were investigated using a combination of chemical separations and on-line radiation detection methods. {sup 242}Es was produced via the {sup 233}U({sup 14}N,5n){sup 242}Es reaction at a beam energy of 87 MeV (on target) in the lab system, and was found to decay with a half-life of 11 {+-} 3 seconds. The ECDF of {sup 242}Es showed a highly asymmetric mass distribution with an average pre-neutron emission… more
Date: January 5, 2000
Creator: Shaughnessy, Dawn A.
Partner: UNT Libraries Government Documents Department
open access

Electron-impact ionization of atomic hydrogen

Description: Since the invention of quantum mechanics, even the simplest example of collisional breakup in a system of charged particles, e{sup {minus}} + H {r_arrow} H{sup +} + e{sup {minus}} + e{sup {minus}}, has stood as one of the last unsolved fundamental problems in atomic physics. A complete solution requires calculating the energies and directions for a final state in which three charged particles are moving apart. Advances in the formal description of three-body breakup have yet to lead to a viable… more
Date: February 14, 2000
Creator: Baertschy, Mark D.
Partner: UNT Libraries Government Documents Department
open access

Inertial Conference Fusion Semiannual Report October 1999 - March 2000, Volume 1, Number 1

Description: This first issue of the ''ICF Semiannual Report'' contains articles whose diverse subjects attest to the broad technical and scientific challenges that are at the forefront of the ICF program at LLNL. The first article describes the progress being made at solving the surface roughness problem on capsule mandrels. All NIF capsule options, except machined beryllium, require a mandrel upon which the ablator is deposited. This mandrel sets the baseline sphericity of the final capsule. Problems invo… more
Date: March 1, 2000
Creator: Hammel, B. A.
Partner: UNT Libraries Government Documents Department
open access

Lasershot peening--a means to strengthen metals

Description: Lasershot peening is an emerging modern process that impresses a compressive stress into the surfaces of metals, improving their operational lifetime. Almost everyone is familiar with taking a strip of metal or a wire and bending it multiple times until it breaks. In this situation, when the metal is bent, the surface of outer radius is stretched into a tensile state. Under tension, any flaw or micro-crack will grow in size with each bending of the metal until the crack grows through the entire… more
Date: March 1, 2000
Creator: Chen, H. L.
Partner: UNT Libraries Government Documents Department
open access

Inertial fusion technology spin-offs-history provides a glimpse of the future

Description: The development and demonstration of inertial fusion is incredibly challenging because it requires simultaneously controlling and precisely measuring parameters at extreme values in energy, space, and time. The challenges range from building megajoule (10{sup 6} J) drivers that perform with percent-level precision to fabricating targets with submicron specifications to measuring target performance at micron scale (10{sup -6} m) with picosecond (10{sup -12} s) time resolution. Over the past 30 y… more
Date: March 7, 2000
Creator: Powell, H
Partner: UNT Libraries Government Documents Department
open access

The Virgin of Verona and the Queen of the Nile

Description: Thesis written by a student in the UNT Honors College discussing William Shakespeare's characters, Juliet and Cleopatra. The author examines both characters as strong women doing their best to take control of the paternalistic worlds they live in.
Date: Spring 2000
Creator: Cobos, Cara
Partner: UNT Honors College
open access

Cooling of highly charged ions in a Penning trap

Description: Highly charged ions are extracted from an electron beam ion trap and guided to Retrap, a cryogenic Penning trap, where they are merged with laser cooled Be{sup +} ions. The Be{sup +} ions act as a coolant for the hot highly charged ions and their temperature is dropped by about 8 orders of magnitude in a few seconds. Such cold highly charged ions form a strongly coupled nonneutral plasma exhibiting, under such conditions, the aggregation of clusters and crystals. Given the right mixture, these … more
Date: March 31, 2000
Creator: Gruber, L
Partner: UNT Libraries Government Documents Department
open access

The ideal strength and mechanical hardness of solids

Description: Relationships between intrinsic mechanical hardness and atomic-scale properties are reviewed, Hardness scales closely and linearly with shear modulus for a given class of material (covalent, ionic or metallic). A two-parameter fit and a Peierls-stress model produce a more universal scaling relationship, but no model can explain differences in hardness between the transition metal carbides and nitrides. Calculations of ''ideal strength'' (defined by the limit of elastic stability of a perfect cr… more
Date: April 1, 2000
Creator: Krenn, Christopher
Partner: UNT Libraries Government Documents Department
open access

Image reconstruction for a Positron Emission Tomograph optimized for breast cancer imaging

Description: The author performs image reconstruction for a novel Positron Emission Tomography camera that is optimized for breast cancer imaging. This work addresses for the first time, the problem of fully-3D, tomographic reconstruction using a septa-less, stationary, (i.e. no rotation or linear motion), and rectangular camera whose Field of View (FOV) encompasses the entire volume enclosed by detector modules capable of measuring Depth of Interaction (DOI) information. The camera is rectangular in shape … more
Date: April 1, 2000
Creator: Virador, Patrick R.G.
Partner: UNT Libraries Government Documents Department
open access

An implicit Smooth Particle Hydrodynamic code

Description: An implicit version of the Smooth Particle Hydrodynamic (SPH) code SPHINX has been written and is working. In conjunction with the SPHINX code the new implicit code models fluids and solids under a wide range of conditions. SPH codes are Lagrangian, meshless and use particles to model the fluids and solids. The implicit code makes use of the Krylov iterative techniques for solving large linear-systems and a Newton-Raphson method for non-linear corrections. It uses numerical derivatives to const… more
Date: April 1, 2000
Creator: Knapp, Charles E.
Partner: UNT Libraries Government Documents Department
open access

Measurement of a Weak Polarization Sensitivity to the Beam Orbit of the CEBAF Accelerator

Description: An accelerator-based experiment was performed using the CEBAF accelerator of the Thomas Jefferson National Accelerator Facility to investigate a predicted sensitivity of the beam polarization to the vertical betatron orbit in the recirculation arcs. This is the first measurement of any such effect at CEBAF, and provides information about the polarized beam delivery performance of the accelerator. A brief description of the accelerator is given, followed by the experimental methods used and the … more
Date: April 1, 2000
Creator: Grames, Joseph
Partner: UNT Libraries Government Documents Department
open access

Microcalorimetry and the transition-edge sensor

Description: Many scientific and industrial applications call for quantum-efficient high-energy-resolution microcalorimeters for the measurement of x rays. The applications driving the development of these detectors involve the measurement of faint sources of x rays in which few photons reach the detector. Interesting astrophysical applications for these microcalorimeters include the measurement of composition and temperatures of stellar atmospheres and diffuse interstellar plasmas. Other applications of mi… more
Date: April 1, 2000
Creator: Lindeman, M A
Partner: UNT Libraries Government Documents Department
open access

Concurrences in the U. S. Supreme Court

Description: Thesis written by a student in the UNT Honors College discussing different types of opinions within the United States Supreme Court, with an emphasis on the history and practice of concurrences.
Date: April 3, 2000
Creator: Watson, Takiesha
Partner: UNT Honors College
open access

P-type doping of GaN

Description: After implantation of As, As + Be, and As + Ga into GaN and annealing for short durations at temperatures as high as 1500 C, the GaN films remained highly resistive. It was apparent from c-RBS studies that although implantation damage did not create an amorphous layer in the GaN film, annealing at 1500 C did not provide enough energy to completely recover the radiation damage. Disorder recovered significantly after annealing at temperatures up to 1500 C, but not completely. From SIMS analysis, … more
Date: April 10, 2000
Creator: Wong, R.K.
Partner: UNT Libraries Government Documents Department
open access

Baryon stopping and hadronic spectra in Pb-Pb collisions at 158 GeV/nucleon

Description: Baryon stopping and particle production in Pb+Pb collisions at 158 GeV/nucleon are studied as a function of the collision centrality using new proton, antiproton, charged kaon and charged pion production data measured with the NA49 experiment at the CERN Super Proton Synchrotron (SPS). Stopping, which is measured by the shift in rapidity of net protons or baryons from the initial beam rapidity, increases in more central collisions. This is expected from a geometrical picture of the collisions. … more
Date: April 12, 2000
Creator: Cooper, Glenn E.
Partner: UNT Libraries Government Documents Department
open access

Adolescent Goals and Their Reports of What They do to Achieve Those Goals

Description: Twenty-five adolescents' ranking of a set of equally highly valued goals on a Paired-comparisons Survey was compared with what adolescents say they are doing to achieve those goals. Results of the Paired-comparisons Survey showed that adolescents ranked career, interpersonal, and educational goals rather high and reputation and self-presentation goals rather low. Results analyzed with a contingency coefficient and biserial correlation indicated that not all number one ranked goals had the same … more
Date: May 2000
Creator: Lucky, Derek
Partner: UNT Libraries
open access

Analysis and Development of Post Secondary Curriculum on Sustainability

Description: This thesis examines existing curricula at colleges and universities about sustainability and uses results to develop an introductory post secondary course curriculum. The proposed course is organized around three major elements - - science, philosophy, and economics - - all integral to understanding sustainability. Materials needed to teach the proposed 3-semester hour course including syllabus, teaching modules, transparencies, handouts, and exams were developed. Suggestions on how to teach a… more
Date: May 2000
Creator: White, Miki Machell
Partner: UNT Libraries

An Analysis of the Composition Process of Bartók's Eight Improvisations on Hungarian Peasant Songs, Op. 20

Description: This is a study of Bartók's compositional process as it relates to the Improvisations, Op. 20. The study, which focuses on the analysis of the draft manuscript 50PS1, compares the draft and other relevant sources with the final composition. Bartók's framework for the entire Improvisations is based on a compositional strategy of pairing individual improvisations combined with systematic revision of the draft copy by the introduction of tritones as tonal equivalents and movement by fifths from se… more
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Date: May 2000
Creator: Kochbeck, Olivia M.
Partner: UNT Libraries
open access

An Analytical Study of the Variations on the Theme of Paganini's Twenty-Fourth Caprice, Op. 1 by Busoni, Friedman, and Muczynski

Description: The purpose of this study is to analyze sets of variations on Paganini's theme by three twentieth-century composers: Ferruccio Busoni, Ignaz Friedman, and Robert Muczynski, in order to examine, identify, and trace different variation techniques and their applications. Chapter 1 presents the purpose and scope of this study. Chapter 2 provides background information on the musical form "theme and variations" and the theme of Paganini's Twenty-fourth Caprice, Op. 1. Chapter 2 also deals with the q… more
Date: May 2000
Creator: Ahn, Kwang Sun
Partner: UNT Libraries
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