Physical Sciences and Mathematics Commons^™

Direct Memory Acquisition Of Fast Analog Signals, Syed Javaid Iqbal

Masters Theses

A fast data transfer computer circuit is developed using the direct memory acquisition (DMAC) technique. For this purpose Z-80 microcomputer ·chips, manufactured by Ziolog, were used. The direct memory acquisition circuitry was developed in several stages and required both hardware and software development. An erasable programmable read only memory (EPROM) programmer was built for reading and loading the system program. The design, construction, and testing of the DMAC system are discussed in detail and an example of the use of this system for collecting data is given.

(E,2e) Spectroscopic Investigations Of The Spectral Momentum Densities Of Thin Carbon Films, John Robert Dennison

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An (e,2e) electron scattering spectrometer has been constructed and used for the first time to investigate the spectral momentum density of the valence bands of a solid target. This technique provides fundamental information about the electronic structure of both crystalline and amorphous solids. The three fundamental quantities, the band structure, electron density of states, and electron momentum distribution can be simultaneously derived from the measured (e,2e) cross section.

A review of single electron and (e,2e) scattering theory is given with an emphasis on scattering from solids. The effects of multiple scattering are discussed and a method of deconvoluting those effects …

Absorption Cross-Sections Of Sodium Diatomic Molecules, Zeng-Shevan Fong

Physics Theses & Dissertations

The absorption cross sections of sodium dimers were studied using a heat pipe over operating in the non-heat-pipe mode. Three wavelength regions were observed. They are in the red, the green-blue, and the near ultraviolet regions. The absorption cross section depends on the wavelength of the incident light. Representative peak values for the v"=0 progression in the red and green-blue regions are 2.59 A sup 2 (average value) and 11.77 A sup 2 (T_ave=624 K). The value for the C greater than X transitions is several tenths A sup 2. The cross sections were measured from absorption spectra …

The Design And Construction Of Microprocessor-Computer Controlled Rapid Scanning Fiberoptic Spectrophotometer, Kathleen Marie Tobin

Masters Theses

Conventional spectrophometers require the transfer of a sample to a cuvette for obtaining spectra. The measurement of absorbance in situ can be accomplished using a fiber optic probe which can be placed directly in the sample. The fiber optic probe also minimizes environmental factors such as thermal or vibrational which may affect the absorbing species. A rapid scanning speed allows for essentially simultaneous wavelength monitoring.

The effect of coupling a rapid scanning spectrophotometer with a fiber optic probe provides for an extremely versatile system. When used in comjunction with a microprocessor or computer, this approach offers advantages such as data …

A Study Of Integral Equations For Computing Radial Distribution Functions, Zainuriah Hassan

Masters Theses

Integral equation T (a two parameter equation of the Ornstein-Zernike form) is studied for computing the radial distribution functions of simple classical fluids interacting pairwise according to the Lennard-Jones 6-12 potential function. Numerical calculations are done on a computer for the system in the gas and liquid phases. At a high temperature, equation T results are found to agree very well with equation C when the parameters are chosen in a similar way. At a temperature slightly above the critical temperature, results from other sources over a wide density range. In equation T, by varying two of the parameters, the …

Minimal Norm Constrained Interpolation, Larry Dean Irvine

Mathematics & Statistics Theses & Dissertations

In computational fluid dynamics and in CAD/CAM a physical boundary, usually known only discreetly (say, from a set of measurements), must often be approximated. An acceptable approximation must, of course, preserve the salient features of the data (convexity, concavity, etc.) In this dissertation we compute a smooth interpolant which is locally convex where the data are locally convex and is locally concave where the data are locally concave.

Such an interpolant is found by posing and solving a minimization problem. The solution is a piecewise cubic polynomial. We actually solve this problem indirectly by using the Peano kernel theorem to …

Copper Electrodeposition In A Magnetic Field, Hiroshi Takeo

Dissertations and Theses

The effect of a magnetic field on copper electrodeposition was investigated. Copper was electrodeposited onto square copper cathodes 1 sq cm in area from an aqueous solution (0.5 M CuSO₄, 0.5 M H₂SO₄. A glass cell was placed between the pole pieces of an electromagnet, and the magnetic fields applied were in the range from 0 to 12.5 kG. The current density was in the range from 80 mA/sq cm to 880 mA/sq cm. In each of the experiments, cell current, cell voltage, and cell temperature were monitored with a microcomputer. The weight …

Confinement Of Electron Orbits And The Interaction Between The Electron Beam And Cavity Modes In The Orbitron Maser, Wlodzimierz Nakonieczny

Doctoral Dissertations

The Orbitron maser, developed over recent years in the University of Tennessee Plasma Laboratory, is an alternative microwave source, capable of producing microwave radiation up to the submillimeter range. It operates on the basis of interaction between an electrostatically confined electron cloud and electromagnetic field in the Orbitron resonator. Good confinement of the cloud is very important for an efficient operation of the Orbitron, and is directly related to the shape of electron orbits in the device. It appears that the radial confinement can be determined by two simple criteria concerning the electron's angular momentum L and energy E. The …

Applications Of A Direct Fast Field/Reflectivity Method To Wave Propagation Modeling In Underwater Acoustic And Solid Earth Seismic Environments, Gerard Joseph Tango

University of New Orleans Theses and Dissertations

A new method is discussed for exact rapid computation of the depth-dependent Green's function occuring in full integral solutions to the acoustic and elastic Helmholtz wave equation, allowing calculations of underwater acoustic propagation loss and full wavefield synthetic seismograms, in range-independent plane stratified media.

Feasibility Studies Of Conversion Electron Mossbauer Spectroscopy (Cems) Of Iron-Doped Inp, Edward Agyekum

Physics Theses & Dissertations

An electron detector for conversion electron Mossbauer spectroscopy (CEMS) has been designed and built. Tests have been performed to study the effects on the electron detector resolution with respect to high anode voltage, He/CH₄ gas flow rate, and counting rate. These parameters have been optimized to detect the 7.3 keV conversion electrons emitted following resonant absorption of the 14.4 keV source gamma-rays associated with the Mossbauer effect using ⁵⁷Fe nuclei. CEMS spectra have been obtained using standard ⁵⁷Fe enriched and natural iron samples. CEMS spectra and Mossbauer transmission spectra have also been obtained for iron-compensated InP (InP:Fe) …

Analysis Of A Rocket-Borne Resonant Scatter System For Measurement Of Atomic Oxygen, Neil B. Myers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A computer model has been developed at Utah State University for interpreting the results of a rocket-borne resonant scatter measurement system using 1304 A radiation. Atomic oxygen densities are obtained from 65 to 140 km from three rocket flights. The resolution of the system is < 0.1 km, and considerable structure has been observed. The variety of shapes exhibited by the three profiles suggest a dynamic nature to atomic oxygen density profiles in the lower ionosphere. Maximum densities between 2.6 x 10¹¹ and 1.2 x 10¹² cm^-3 were observed at altitudes between 92 and 95 km.

The Pauli Operator Correction In The Effective Λn Interaction, Jaleh Owliaei

Masters Theses

Hypernuclear structure calculations performed for ⁶_ΛLi, ⁷_ΛLi, and ¹⁶_Λ0 have reproduced the 1_Λ=1 levels inferred from the recent (k, Π) reactions. However the 1_Λ=0, groundstate of ¹⁶_Λ0 is overbound by 6 MeV in these calculations, indicating a density dependence in the effective ΛN interaction in the interior of the heavier system. In this work corrections to the ¹⁶_Λ0 effective interaction are introduced in terms of a Brueckner-Goldstone G-matrix with a modified Pauli operator. The G-matrix of ¹⁶_Λ0 derived from that of ⁶_ΛLi …

Resonant Electron Transfer And K-Shell Excitation Of Lithiumlike Projectiles In Collisions With Neutral Gas Targets, Carollyn Sloan Oglesby

Masters Theses

No abstract provided.

The Impeachment And Trial Of Secretary Of War William Worth Belknap, Duane Edward Holthof

Masters Theses

The purpose of this thesis is to give an account of the events which lead to the resignation of Secretary of War William Worth Belknap in 1876, to examine the circumstances surrounding his impeachment, and to study the testimony in his Senate trial.

Although Belknap was not convicted on charges of accepting bribes, most of those senators who voted to acquit him did so on the technical ground that the Senate lacked the jurisdiction to try a private citizen. The evidence in the case clearly indicated Belknap's involvement, and there seems little doubt that if Belknap did not know what …

Construction And Testing Of A New Atomic Physics Beam Line At The Western Michigan University Accelerator Laboratory, William Andrew Hollerman

Masters Theses

A new beam line containing a differentially-pumped gas cell and charge state analyzing magnet was constructed for the purpose of measuring a wide variety of atomic inner-shell processes, such as excitation, ionization, and charge transfer. The completed system will be able to measure these individual atomic processes using coincidence techniques. Initial testing of the beam line was performed using 40MeV S⁺⁷+Ar collisions to determine the effect of the collimating slit size on the measured x-ray cross sections. These measurements showed that the slip size on the measured x-ray cross sections. These measurements showed that the slit size affects …

Turbulent Disruptions From The Strauss Equations, Jill Potkalitsky Dahlburg

Dissertations, Theses, and Masters Projects

The subject of this thesis is an analysis of results from pseudospectral simulation of the Strauss equations of reduced three-dimensional magnetohydrodynamics. We have solved these equations in a rigid cylinder of square cross section, a cylinder with perfectly conducting side walls, and periodic ends. We assume that the uniform-density magnetofluid which fills the cylinder is resistive, but inviscid. Situations which we are considering are in several essential ways similar to a tokamak-like plasma; an external magnetic field is imposed, and the plasma carries a net current which produces a poloidal magnetic field of sufficient strength to induce current disruptions. These …

First Principles Structure Calculations Using The General Potential Lapw Method, Su-Huai Wei

Dissertations, Theses, and Masters Projects

We have developed a completely general first principles self-consistent full-potential linearized-augmented-plane-wave (LAPW) method program within the density functional formalism to calculate electronic band structure, total energy, pressure and other quantities. No symmetry assumptions are used for the crystal structure. Shape unrestricted charge densities and potentials are calculated inside muffin-tin (MT) spheres as well as in the interstitial regions. All contributions to the Hamiltonian matrix elements are completely taken into account. The core states are treated fully relativistically using the spherical part of the potential only. Scalar relativistic effects are included for the band-states, and spin-orbit coupling is included using a …

Stability And Transition Of The Driven Magnetohydrodynamic Sheet Pinch, Russell B. Dahlburg

Dissertations, Theses, and Masters Projects

The stability and transition properties of a bounded, current carrying magnetofluid are explored, using the hydrodynamic theory developed for plane shear flows as a guide. A driven magnetohydrodynamic sheet pinch equilibrium is employed. A sixth order, complex eigenvalue equation which governs the normal modes of small oscillations is derived, and solved numerically by the Chebyshev tau method. Eigenfunctions are shown, as well as the curve of neutral stability. The locus of critical Lundquist numbers has the form of a hyperbola. The nonlinear stability of a primary disturbance of the system is considered. For regions in parameter space close to criticality, …

Fourth Order Mass Splitting In The Bag Model, Timothy John Havens

Dissertations, Theses, and Masters Projects

The fourth order diagrams in the perturbative expansion of the hadron mass are calculated using the static spherical cavity approximation to the MIT bag model and Quantum Chromodynamics (QCD). Only terms with color matrix structure different than that of the second order diagrams are retained.;The fourth order mass splitting is found to be smaller than the second order splitting by a factor of three or more.

Combined Translational-Rotational Jumps In Solid (Alpha)-Co And Co(,2), Shang-Bin Liu

Dissertations, Theses, and Masters Projects

Combined translational-rotational jumps in two orientationally ordered solids, (alpha)-CO and CO(,2), have been measured using C('13) NMR. In the Pa3 structure of these solids, a molecule which jumps to a neighboring (presumably vacant) site will reorient, due to the orientationally ordered structure.;The rates of translation and rotation have been measured independently by using different NMR techniques. The rotations were detected at high field (14.7 MHz) through the modulation of the chemical shift anisotropy; spin echoes and stimulated echoes were used. The translational jumps modulate the dipolar interactions and were studied at low fields (1.256 MHz) with line narrowing and Slichter-Ailion …