You limited your search to:

  Partner: UNT Libraries
 Degree Discipline: Physics
A Non-equilibrium Approach to Scale Free Networks

A Non-equilibrium Approach to Scale Free Networks

Date: August 2012
Creator: Hollingshad, Nicholas W.
Description: Many processes and systems in nature and society can be characterized as large numbers of discrete elements that are (usually non-uniformly) interrelated. These networks were long thought to be random, but in the late 1990s, Barabási and Albert found that an underlying structure did in fact exist in many natural and technological networks that are now referred to as scale free. Since then, researchers have gained a much deeper understanding of this particular form of complexity, largely by combining graph theory, statistical physics, and advances in computing technology. This dissertation focuses on out-of-equilibrium dynamic processes as they unfold on these complex networks. Diffusion in networks of non-interacting nodes is shown to be temporally complex, while equilibrium is represented by a stable state with Poissonian fluctuations. Scale free networks achieve equilibrium very quickly compared to regular networks, and the most efficient are those with the lowest inverse power law exponent. Temporally complex diffusion also occurs in networks with interacting nodes under a cooperative decision-making model. At a critical value of the cooperation parameter, the most efficient scale free network achieves consensus almost as quickly as the equivalent all-to-all network. This finding suggests that the ubiquity of scale free networks in nature ...
Contributing Partner: UNT Libraries
Theoretical and Experimental Investigations Concerning Microgels of Varied Spherical Geometries

Theoretical and Experimental Investigations Concerning Microgels of Varied Spherical Geometries

Date: August 2012
Creator: Wahrmund, Joshua Joseph
Description: Polymer gels have been studied extensively due to their ability to simulate biological tissues and to swell or collapse reversibly in response to external stimuli. This work presents a variety of studies using poly-N-isopropylacrylamide (PNIPA) hydrogels. The projects have been carried out both in the lab of Dr. Zhibing Hu and in collaboration with others outside of UNT: (1) an analysis of the swelling kinetics of microgel spherical shells prepared using a novel design of microfluidic devices; (2) a comparison of the drug-release rates between nanoparticle structures having either core or core-with-shell (core-shell) designs; (3) an investigation into the thermodynamics of swelling for microgels of exceedingly small size.
Contributing Partner: UNT Libraries
Ultrafast Spectroscopy of Hybrid Ingan/gan Quantum Wells

Ultrafast Spectroscopy of Hybrid Ingan/gan Quantum Wells

Date: August 2012
Creator: Mahat, Meg Bahadur
Description: Group III nitrides are efficient light emitters. The modification of internal optoelectronic properties of these materials due to strain, external or internal electric field are an area of interest. Insertion of metal nanoparticles (MNPs) (Ag, Au etc) inside the V-shaped inverted hexagonal pits (IHP) of InGaN/GaN quantum wells (QWs) offers the potential of improving the light emission efficiencies. We have observed redshift and blueshift due to the Au MNPs and Ag MNPs respectively. This shift could be due to the electric field created by the MNPs through electrostatic image charge. We have studied the ultrafast carrier dynamics of carriers in hybrid InGaN/GaN QWs. The change in quantum confinement stark effect due to MNPs plays an important role for slow and fast carrier dynamics. We have also observed the image charge effect on the ultrafast differential transmission measurement due to the MNPs. We have studied the non-linear absorption spectroscopy of these materials. The QWs behave as a discharging of a nanocapacitor for the screening of the piezoelectric field due to the photo-excited carriers. We have separated out screening and excitonic bleaching components from the main differential absorption spectra of InGaN/GaN QWs.
Contributing Partner: UNT Libraries
Variational Wave Function for Sodium

Variational Wave Function for Sodium

Date: August 1953
Creator: Smith, Daniel Montague
Description: The practical method of applying the variation principle to the calculation of the energy of an atom demands a trial function which contains variable parameters. The previous work done using this approach was based on the use of some combination of hydrogenic wave functions containing parameters inserted in appropriate places. The present calculation of the energy of the eleven-electron atom has been brought about using this method.
Contributing Partner: UNT Libraries
Operation and Control of a Radiofrequency Ion Source

Operation and Control of a Radiofrequency Ion Source

Date: August 1953
Creator: Paulissen, George T.
Description: This thesis examines the operation and control of a radiofrequency ion source.
Contributing Partner: UNT Libraries
Neutron Density Depression Due to an Oblate Spheroidal Detector

Neutron Density Depression Due to an Oblate Spheroidal Detector

Date: January 1954
Creator: Trammell, Margaret Ruth
Description: In this paper, two projects have been undertaken. First, Workman's calculations have been checked to a higher degree of approximation to determine the accuracy of his method. Second, a new set of boundary conditions has been developed for obtaining solutions of the neutron diffusion equation which do not depend on the solution of the equation inside the detector.
Contributing Partner: UNT Libraries
Dynamical Friction Coefficients for Plasmas Exhibiting Non-Spherical Electron Velocity Distributions

Dynamical Friction Coefficients for Plasmas Exhibiting Non-Spherical Electron Velocity Distributions

Date: August 1961
Creator: Williams, G. Bruce
Description: This investigation is designed to find the net rate of decrease in the component of velocity parallel to the original direction of motion of a proton moving through an electron gas exhibiting a non-spherical velocity distribution.
Contributing Partner: UNT Libraries
Energy Losses of Protons Projected through a Plasma Due to Collisions with Electrons of the Plasma for a Variety of Non-Maxwellian Electron Velocity Distributions

Energy Losses of Protons Projected through a Plasma Due to Collisions with Electrons of the Plasma for a Variety of Non-Maxwellian Electron Velocity Distributions

Date: August 1961
Creator: Kregel, Mark Douglas
Description: The purpose of this thesis is to study energy losses suffered by protons in traversing a plasma through collision with the electrons of the plasma. For these electrons a variety of non-Maxwellian velocity distributions are assumed.
Contributing Partner: UNT Libraries
A Computer Analysis of Complex Gamma-Ray Spectra

A Computer Analysis of Complex Gamma-Ray Spectra

Date: August 1965
Creator: Cunningham, William K.
Description: The purpose of this investigation was to provide a method for determining the relative intensities of all gamma rays in a particular spectrum, and thereby determine the relative transition probabilities.
Contributing Partner: UNT Libraries
Electron Transport in Bismuth at Liquid Helium Tempratures

Electron Transport in Bismuth at Liquid Helium Tempratures

Date: May 1964
Creator: Newell, James M.
Description: To obtain information on the band structure of bismuth, galvanomagnetic potentials were measured in a single crystal at liquid-helium and liquid-nitrogen temperatures. These measurements were analyzed for information on the different carriers, particularly for the existence of a high-mobility band of holes.
Contributing Partner: UNT Libraries