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[Investigation of transitions from order to chaos in dynamical systems]. Annual progress report

Description: This report discusses: torus structure in higher dimensional hamiltonian systems; particle heating and stochastic web diffusion; scaling behavior of coupled conservative nonlinear systems; box counting algorithm and dimensional analysis of a pulsar; and universality of coupled nonlinear systems. (LSP)
Date: December 31, 1990
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Binary-binary collisions involving main-sequence stars, white dwarfs and neutron stars in globular clusters

Description: We consider collisions between dynamically-evolved primordial binaries consisting of main-sequence stars, white dwarfs and neutron stars in globular clusters. In our four-body binary-binary scattering experiments, we allow stars to ``stick`` if they pass close enough to each other, which leads to the formation of a wide variety of exotic objects. Most of these objects have binary companions. Also, relatively clean exchange interactions can produce binaries containing neutron stars that eventual… more
Date: December 31, 1993
Creator: Leonard, P. J. T. & Davies, M. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Fundamentals of the Cyclotron Up-Scattering Process

Description: Gamma-ray bursts (GRBs) remain an enigmatic astrophysical phenomenon some 20 years after their discovery. One of their unique characteristics is their continuum spectra which tend to be deficient in soft X-rays. Most of the energy of continuum emission comes from photons with energy above 100 keV (Epstein 1986). Following the recent detection of double absorption features in GB870303 and GB880205, and the interpretation of these features as the fundamental and first harmonic cyclotron lines gre… more
Date: December 31, 1991
Creator: Ho, Cheng; Epstein, R. I. & Fenimore, E. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The ALEXIS data processing package: An IDL-based system

Description: The ALEXIS experiment is a mini-satellite containing six wide angle EUV/ultrasoft x-ray telescopes. Its purpose is to map out the sky in three narrow (5%) bandpasses around 66, 71, and 93 eV. The 66 and 71 eV bandpasses are centered on intense Fe emission lines which are characteristic of million-degree plasmas such as the one thought to produce the soft x-ray background. The 93 eV bandpass is not near any strong emission lines and is more sensitive to continuum sources. The emission will be la… more
Date: December 31, 1991
Creator: Bloch, J. J.; Smith, B. W. & Edwards, B. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Physics studies with ICARUS and a hybrid ionization and scintillation fiber detector

Description: We discuss the physics possibilities for the ICARUS detector currently being tested at CERN. The physics potential goes from a massive proton decay detector to the study of solar neutrinos. In addition, the detection of {nu}{sub {mu}} {yields} {nu}{sub {tau}} and {nu}{sub e} {yields} {nu}{sub {tau}} will be possible with such a detector. One major topic involves the possibility of a complete determination of the MSW solar neutrino parameters with the ICARUS. The possibility of detecting WIMPS w… more
Date: December 31, 1992
Creator: Cline, D. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Tidal disruption of a star by a supermassive black hole

Description: The analysis of stars in galactic nuclei that are captured and tidally disrupted by a black hole of mass > 10{sup 6} M{sub {circle_dot}} requires the inclusion of general relativistic effects. We present the first numerical study of tidal breakup of a 1M{sub {circle_dot}} main sequence star by a 10{sup 7} M{sub {circle_dot}} black hole. We use a smoothed particle code to solve the hydrodynamic equations for a relativistic fluid in a static curved spacetime geometry to analyze, among other thing… more
Date: December 31, 1991
Creator: Laguna, P.; Miller, W. A. & Zurek, W. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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CDM and Omega in the local neighborhood

Description: Peebles has suggested an interesting method to trace back in time positions of galaxies called the least action method. This method applied on the Local Group galaxies seems to indicate that we live in an {Omega} {approx} 0.1 Universe. The authors have studied a cold dark matter (CDM) N-body simulation with {Omega} = 0.2 and H = 50kms{sup {minus}1}/Mpc and compare trajectories traced back from the Least Action Principle and the center of mass of the particle forming CDM halos. They have shown t… more
Date: December 31, 1995
Creator: Dunn, A. M. & Laflamme, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Taxonomy of gamma ray burster data using a self-organizing neural network

Description: This paper summarizes the results of a signal taxonomy study of gamma ray burst (GRB) data acquired with sensors on-board the Pioneer-Venus Orbiter (PVO) spacecraft. GRB events produce large fluxes of gamma rays with durations of seconds to minutes and have been observed since the early 1970`s. The true nature of GRBs is still unknown and several competing theories exist. A fundamental point of contention among such theories is whether or not different types of GRB exist. If different types of … more
Date: December 31, 1993
Creator: Baumgart, C. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The influence of CDM on the dynamical estimate of {Omega} in the local neighborhood

Description: Peebles has suggested an interesting method to trace back in time positions of galaxies called the least action method. This method applied on the Local Group galaxies seems to indicate that we live in an {Omega}{approx} 0.1 Universe. We have studied a CDM N-body simulation with {Omega} = 0.2 and H = 50kms{sup {minus}1}/Mpc and compare trajectories traced back from the Least Action Principle and the center of mass of the particle forming CDM halos. We have shown that the agreement between these… more
Date: December 31, 1994
Creator: Dunn, A. M. & Laflamme, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Statistical mechanics of nonlinear coherent structures: Kinks in the {Phi}{sup 6} model

Description: We study the thermodynamics of kinks in the {Phi}{sup 6} model using a Langevin code implemented on a massively parallel computer. This code can be used to study first order dynamical phase transitions which exhibit multiple length and time scales. The classical statistical mechanics of a 1 + 1-dimensional field theory reduces to a time-independent quantum problem in one dimension via the transfer integral method. Exact solutions of the Schroedinger equation exist for the {Phi}{sup 6} potential… more
Date: December 31, 1994
Creator: Habib, S. & Saxena, A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The second coming of cold dark matter?

Description: While the standard cold dark matter (CDM) model has received numerous marks against it on the basis of a variety of observational data, the prediction of high {Sigma}{Upsilon}, the pairwise-velocity dispersion between galaxies, on small (megaparsec) scales was reported as perhaps one of its greatest failings. Here, we reexamine the case of CDM and {Sigma}{Upsilon}, with high-resolution numerical simulations. The statistic was measured in simulations, in artificial galaxy catalogs, and in the Cf… more
Date: December 31, 1994
Creator: Zurek, W. H.; Bromley, B. C. & Warren, M. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Nuclear astrophysics

Description: The problem of core-collapse supernovae is used to illustrate the many connections between nuclear astrophysics and the problems nuclear physicists study in terrestrial laboratories. Efforts to better understand the collapse and mantle ejection are also motivated by a variety of interdisciplinary issues in nuclear, particle, and astrophysics, including galactic chemical evolution, neutrino masses and mixing, and stellar cooling by the emission of new particles. The current status of theory and … more
Date: December 31, 1992
Creator: Haxton, W. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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[Growth and nonlinearity]. Progress report

Description: The research centered on the physics of growth. One particular focus was the spiral patterns seen in excitable media, such as the chemical reaction of Belousov and Zhabatinskii, and the aggregation of the slime mold, Dictyostelium Discoideum. Another area of interest is the statistical roughness of the growth front itself. For example, when growing thin films, the roughness of the surface is very important for the ultimate quality of the film. Besides its direct technological relevance, this pr… more
Date: December 31, 1993
Creator: Savit, R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The Neutrino Process and Neutrino R-Process

Description: Almost all of the 3 {center_dot} 10{sup 53} ergs released in a core-collapse supernova is carried off by the neutrinos emitted from the cooling neutron star. These neutrinos can excite nuclei in the mantle of the star by their neutral and charged current reactions, leading to the spallation of nucleonsa and {alpha}-particles and the production of new daughter nuclei, I will describe rather detailed network calculations that suggest this ``neutrino process`` is an important nucleosynthesis mecha… more
Date: December 31, 1991
Creator: Haxton, W. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Inflation after COBE: Lectures on inflationary cosmology

Description: In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the ``initial data`` for structure form… more
Date: December 31, 1992
Creator: Turner, M. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Nonlinear self-focus of pulsed-wave beams in Kerr media

Description: A modified finite-difference time-domain method for solving Maxwell`s equations in nonlinear media is presented. This method allows for a finite response time to be incorporated in the medium, physically creating dispersion and absorption mechanisms. The technique models electromagnetic fields in two space dimensions and time and encompasses both the TE{sub z} and TM{sub z} set of decoupled field equations. Aspects of an ultra-short pulsed Gaussian beam are studied in a variety of linear and no… more
Date: December 31, 1992
Creator: Judkins, J. B.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Whispering-gallery mirrors for short-wavelength laser cavities: Shapes and tolerances

Description: The whispering-gallery mirrors desired for use in short-wavelength laser cavities are seen to be highly aspheric and very different from the shapes encountered in conventional optics. Fabrication tolerance are established by examining the effects of various surface imperfections. The mirrors are found to be relatively insensitive to figures errors. The requirements on surface finish are shown to be fairly strict, though less severe than with normal-incidence optics.
Date: December 31, 1991
Creator: Braud, J. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A crystalline quark-hadron mixed phase in neutron stars

Description: The mixed phase of a substance undergoing a first order phase transition has entirely different behavior according as the substance has more than one conserved charge or only one, as in the text book examples. In the latter case the pressure and nature of the phases are constants throughout the coexistence phase. For systems with more than one conserved charge (or independent component) we prove two theorems: (1) The pressure and the nature of the phases in equilibrium change continuously as th… more
Date: August 31, 1994
Creator: Glendenning, N. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Proceedings of the workshop on the production and use of intense radioactive beams at the Isospin Laboratory

Description: These proceedings report the deliberations of a 3 1/2 day workshop on the Production and Use of Intense Radioactive Ion Beams at the Isospin Laboratory, which was held at the Joint Institute for Heavy Ion Research in Oak Ridge, Tennessee, October 1992. The purpose of this workshop was not to duplicate the programs of other recent radioactive ion beam workshops or international conferences that have focused on the scientific concepts which radioactive beams can, and in fact already are, addressi… more
Date: December 31, 1992
Creator: Garrett, J. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Workshop on advances in smooth particle hydrodynamics

Description: This proceedings contains viewgraphs presented at the 1993 workshop held at Los Alamos National Laboratory. Discussed topics include: negative stress, reactive flow calculations, interface problems, boundaries and interfaces, energy conservation in viscous flows, linked penetration calculations, stability and consistency of the SPH method, instabilities, wall heating and conservative smoothing, tensors, tidal disruption of stars, breaking the 10,000,000 particle limit, modelling relativistic co… more
Date: December 31, 1993
Creator: Wingate, C. A. & Miller, W. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Solar neutrinos: theory vs experiment

Description: I review the standard solar model, the disparities between its predictions and the solar neutrino flux measurements of the Homestake and Kamioka II collaborations, and possible particle physics resolutions of this puzzle. The effects of matter, including density fluctuations and turbulence, on solar neutrino oscillations are reviewed, including possibilities for generating time variations in the solar neutrino flux. Finally, I consider possible outcomes and implications of the SAGE/GALLEX galli… more
Date: December 31, 1991
Creator: Haxton, W. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A linear and nonlinear study of Mira

Description: Both linear and nonlinear calculations of the 331 day, long period variable star Mira have been undertaken to see what radial pulsation mode is naturally selected. Models are similar to those considered in the linear nonadiabatic stellar pulsation study of Ostlie and Cox. Models are considered with masses near one solar mass, luminosities between 4000 and 5000 solar luminosities, and effective temperatures of approximately 3000 K. These models have fundamental mode periods that closely match th… more
Date: December 31, 1991
Creator: Cox, A. N. & Ostlie, D. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Complex temporal and spatial patterns in nonequilibrium processes. Final report, December 1, 1987--November 30, 1992

Description: Dynamical systems methods have been used to study bifurcations and pattern formation in nonequilibrium systems. Accomplishments during this period include: information-theoretic methods for analyzing chaos, chemical reactors for studying sustained reaction-diffusion patterns, a reactor exploiting pattern formation to extract short- lived intermediate species, observation of bifurcation from periodic to quasiperiodic rotating chemical spiral patterns, observation of a Turing bifurcation (transit… more
Date: December 31, 1992
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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