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  Access Rights: Public
 Department: Department of Physics
 Collection: UNT Theses and Dissertations
Fractional Brownian motion and dynamic approach to complexity.

Fractional Brownian motion and dynamic approach to complexity.

Date: August 2007
Creator: Cakir, Rasit
Description: The dynamic approach to fractional Brownian motion (FBM) establishes a link between non-Poisson renewal process with abrupt jumps resetting to zero the system's memory and correlated dynamic processes, whose individual trajectories keep a non-vanishing memory of their past time evolution. It is well known that the recrossing times of the origin by an ordinary 1D diffusion trajectory generates a distribution of time distances between two consecutive origin recrossing times with an inverse power law with index m=1.5. However, with theoretical and numerical arguments, it is proved that this is the special case of a more general condition, insofar as the recrossing times produced by the dynamic FBM generates process with m=2-H. Later, the model of ballistic deposition is studied, which is as a simple way to establish cooperation among the columns of a growing surface, to show that cooperation generates memory properties and, at same time, non-Poisson renewal events. Finally, the connection between trajectory and density memory is discussed, showing that the trajectory memory does not necessarily yields density memory, and density memory might be compatible with the existence of abrupt jumps resetting to zero the system's memory.
Contributing Partner: UNT Libraries
Galvanomagnetic Determination of Energy Bands in Arsenic

Galvanomagnetic Determination of Energy Bands in Arsenic

Date: January 1968
Creator: Hathcox, Kyle Lee
Description: A study of the transport properties of a substance requires the determination of a set of transport coefficients by experiment. From these coefficients, the elements of the electrical conductivity tensor, thermoelectric tensor, et cetera can be determined. In this experiment, measurements and analyses of galvanomagnetic effects in a single crystal of arsenic were performed. The measurements were made at liquid-helium temperatures in magnetic fields ranging to 25 kilogauss. The gross isothermal, electrical conductivities have been analyzed to determine various parameters characterizing the energy bands in arsenic.
Contributing Partner: UNT Libraries
Galvanomagnetic Phenomena in Arsenic at Liquid Helium Temperatures

Galvanomagnetic Phenomena in Arsenic at Liquid Helium Temperatures

Date: June 1966
Creator: Yarbrough, Jack Lee
Description: The purpose of this investigation was to study some of the transport effects in a single crystal of arsenic at liquid helium temperatures in a magnetic field up to twenty-four kilogauss. The experimental coefficients determined were the isothermal magnetoresistivity and the isothermal Hall resistivity.
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Gamma Ray Distribution from Neutron Excitation in Cesium

Gamma Ray Distribution from Neutron Excitation in Cesium

Date: January 1969
Creator: Bowers, Richard Morgan
Description: The purpose of this investigation was to analyze the gamma rays resulting from excitation of Cs133 by the inelastic scattering of 14 MeV neutrons and to determine the relative intensity of each gamma ray.
Contributing Partner: UNT Libraries
Gamma Ray Response of a CsI(T1) Crystal to 14 Mev Neutrons

Gamma Ray Response of a CsI(T1) Crystal to 14 Mev Neutrons

Date: August 1958
Creator: Young, Jack Carter
Description: The purpose of this paper is to study the possible excited states in the nucleus of Cs133. At North Texas State College a 100-Kev Cockcroft-Walton accelerator has been constructed for use as a neutron source for exciting various nuclei and for studying the gamma spectra obtained to determine their energy levels.
Contributing Partner: UNT Libraries
Gamma Rays from Cs¹³³ by Inelastic Scattering of Neutrons

Gamma Rays from Cs¹³³ by Inelastic Scattering of Neutrons

Date: August 1960
Creator: McDonald, Perry Frank
Description: The purpose of this investigation was to observe the excited states of the Cs¹³³ nucleus when neutrons are inelastically scattered from the nucleus.
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Gamma Rays from Neutron Excitation of Cs133

Gamma Rays from Neutron Excitation of Cs133

Date: January 1959
Creator: Lamb, Billy Leonard
Description: This thesis explores gamma rays from neutron excitation of Cs133.
Contributing Partner: UNT Libraries
Gamma Rays Resulting from Neutron Scattering in Cesium

Gamma Rays Resulting from Neutron Scattering in Cesium

Date: January 1967
Creator: McAnally, Michael A.
Description: The purpose of this investigation was to attempt to resolve the energy levels of Cs133 that can be excited by inelastic scattering of 14 Mev neutrons.
Contributing Partner: UNT Libraries
Growth and Characterization of β-Iron Disilicide, β-Iron Silicon Germanide, and Osmium Silicides

Growth and Characterization of β-Iron Disilicide, β-Iron Silicon Germanide, and Osmium Silicides

Date: August 2009
Creator: Cottier, Ryan James
Description: The semiconducting silicides offer significant potential for use in optoelectronic devices. Full implementation of the materials, however, requires the ability to tailor the energy gap and band structure to permit the synthesis of heterojunctions. One promising approach is to alloy the silicides with Ge. As part of an investigation into the synthesis of semiconducting silicide heterostructures, a series of β-Fe(Si1−xGex)2 epilayer samples, with nominal alloy content in the range 0 < x < 0.15, have been prepared by molecular beam epitaxy on Si(100). I present results of the epitaxial and crystalline quality of the films, as determined by reflection high-energy electron diffraction, Rutherford backscattering spectroscopy, and double crystal x-ray diffraction, and of the band gap dependence on the alloy composition, as determined by Fourier transform infrared spectroscopy. A reduction in band gap was observed with increasing Ge content, in agreement with previous theoretical predictions. However Ge segregation was also observed in β-Fe(Si1−xGex)2 epilayers when x > 0.04. Osmium silicide films have been grown by molecular beam epitaxy on Si(100). The silicides have been grown using e-beam evaporation sources for both Os and Si onto Si(100) substrates at varying growth rates and temperatures ranging from 600-700ºC. The resulting films have been ...
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Gurevich Magnetomorphic Oscillations in Single Crystals of Aluminum at Helium Temperatures

Gurevich Magnetomorphic Oscillations in Single Crystals of Aluminum at Helium Temperatures

Date: August 1967
Creator: Mollenkopf, Howard Charles
Description: The Sondheimer theory was tested by looking for oscillatory phenomena in a group of single crystals representing a range in dimensions from matchbox geometry to thin-film geometry. The single crystals were identical with respect to impurity content, strain, orientation, surface condition, and probe placement.
Contributing Partner: UNT Libraries