Resource Type

Standard model bosons as composite particles (open access)

Standard model bosons as composite particles

The Standard model of electro-weak interactions is derived from a Nambu, Jona-Lasinio type four-fermion interaction, which is assumed to result from a more basic theory valid above a very high scale {Lambda}. The masses of the gauge bosons and the Higgs are then produced by dynamical symmetry breaking of the Nambu model at an intermediate scale {mu}, and are evolved back to experimental energies via the renormalisation group equations of the Standard model. The weak angle sin{sup 2} ({theta}{sub W}) is predicted to be 3/8 at the scale {mu}, as in grand unified theories, and is evolved back to the experimental value at scale M{sub W}, thus determining {mu} {approximately}10{sup 13}GeV. Predictions for the ratios of the masses of the gauge and the Higgs bosons to the top quark mass, at experimental energies, are also obtained.
Date: January 1, 1990
Creator: Kahana, D.E. (Southeastern Universities Research Association, Newport News, VA (USA). Continuous Electron Beam Accelerator Facility) & Kahana, S.H. (Brookhaven National Lab., Upton, NY (USA))
System: The UNT Digital Library
Schematic model of nuclear spin excitations (open access)

Schematic model of nuclear spin excitations

A simple model to estimate the strength of spin and nonspin collective states is presented. The model was inspired by early schematic models based on energy-weighted sum rules and is a useful tool for interpreting experimental data without the complexities of realistic microscopic calculations. The strength of collective states is calculated by assuming that a single collective state completely exhausts the energy-weighted sum rule. 19 refs.
Date: January 1, 1990
Creator: Boucher, P.M.
System: The UNT Digital Library
Research in theoretical nuclear physics (open access)

Research in theoretical nuclear physics

This report discusses research in the following areas: form factors; mesoniums and glueballs; soliton model of hadrons; color transparency; soliton-soliton interaction; proton spin; and strange quark content of the proton. (LSP)
Date: January 1, 1990
Creator: Liu, Keh-Fei; Draper, T. & Li, Bing An.
System: The UNT Digital Library
The Determinants of Overbuilding: Texas Multifamily Housing Construction in the 1980s (open access)

The Determinants of Overbuilding: Texas Multifamily Housing Construction in the 1980s

"This report isolates the determinants of Texas multifamily construction to identify the factors that led to overbuilding of housing units in the early 1980s and provide information for future planning."
Date: January 1990
Creator: Harris, Jack C.
System: The Portal to Texas History
Electrostatic precipitation of condensed acid mist (open access)

Electrostatic precipitation of condensed acid mist

This project addresses the problem of acid mist formed by condensation of sulfuric acid vapor in flue gas from coal-fired utility boilers. Acid mists can sometimes constitute a significant portion of the total particulate emissions from power plants burning high-sulfur coals. Complete condensation of 10 ppM of acid vapor produces a condensed acid mass loading of about 0.02 gr/dscf or 0.03 lb/MBtu, equivalent to the total allowable mass emissions under the revised (1979) New Source Performance Standards (2). The purpose of this project is to develop and demonstrated a compact, wet electrostatic collector for condensed acid mist in power plant flue gas. The project is organized in two phases. Phase I involved the WESP fabrication, laboratory and pilot combustor testing, and computer modeling. Phase II involves the solicitation of a utility demonstration site, preliminary site measurements, and planning for the demonstration test program. Only Phase II work will be addressed in this discussion which includes: site selection, site measurements, computer modeling and demonstration plan, and phase II reporting. 9 refs., 11 figs., 7 tabs.
Date: January 1, 1990
Creator: unknown
System: The UNT Digital Library
Electrostatic precipitation of condensed acid mist (open access)

Electrostatic precipitation of condensed acid mist

This project addresses the acid mist that is formed by condensation of sulfuric acid vapor in flue gas from coal-fired utility boilers. An acid mist can be formed whenever the flue gas temperature approaches the prevailing acid dew point. This commonly occurs when the gas is subjected to rapid adiabatic cooling in a wet scrubber system for flue gas desulfurization. Acid mists can also sometimes result from unexpected temperature excursions caused by air inleakage, load cycling, and start-up operations. A wet electrostatic precipitator (WESP) is the best control option for acid mist. The mist would blind a fabric filter and attach glass fiber fabrics. A wet ESP is required because the acid would quickly corrode the plates in a conventional dry ESP. The wet ESP also offers the advantages of no rapping reentrainment and no sensitivity to fly ash resistivity. Therefore, this program has been structured around the use of a compact, wet ESP to control acid mist emissions. Progress to date is discussed. 7 refs., 1 fig.
Date: January 1, 1990
Creator: unknown
System: The UNT Digital Library
Summary of All Reported Accidents in Rural Areas of Texas for December 1989 (open access)

Summary of All Reported Accidents in Rural Areas of Texas for December 1989

Monthly report providing tabular statistical information about motor vehicle accidents in rural areas of Texas during 1989, with data broken out by various criteria including number of persons, locations, types of accidents, time of day, and other factors.
Date: January 20, 1990
Creator: Texas. Department of Public Safety. Statistical Services.
System: The Portal to Texas History
Summary of All Reported Accidents in the State of Texas for December 1989 (open access)

Summary of All Reported Accidents in the State of Texas for December 1989

Monthly report providing tabular statistical information about motor vehicle accidents in Texas during 1989, with data broken out by various criteria including number of persons, locations, types of accidents, time of day, and other factors.
Date: January 20, 1990
Creator: Texas. Department of Public Safety. Statistical Services.
System: The Portal to Texas History
Studying oxygen vacancies in ceramics by perturbed angular correlation spectroscopy (open access)

Studying oxygen vacancies in ceramics by perturbed angular correlation spectroscopy

Perturbed angular correlation measurements in tetragonal and cubic zirconia and in ceria are described. A physically reasonable and self-consistent interpretation of these data implies that oxygen vacancies are trapped at a second neighbor position by Cd in tetragonal zirconia and by In in ceria. For Cd in tetragonal zirconia, the vacancy trap energy is found to be 0.44 eV, and the energy barrier between adjacent trap sites is approximately 0.8 eV. The activation energy of an oxygen vacancy hopping between trap sites around {sup 111}Cd in ceria is found to be 0.55 eV. The activation energy for oxygen vacancy hopping in cubic zirconia, as detected by {sup 181}Ta PAC, is about 1.0 eV and independent of the Y concentration. 12 refs., 4 figs.
Date: January 1, 1990
Creator: Su, Han-Tzong; Wang, Ruiping; Fuchs, H.; Gardner, J. A.; Evenson, W. E. & Sommers, J. A.
System: The UNT Digital Library
PAC (perturbed angular correlation) analysis of defect motion by Blume's stochastic model for I = 5/2 electric quadrupole interactions (open access)

PAC (perturbed angular correlation) analysis of defect motion by Blume's stochastic model for I = 5/2 electric quadrupole interactions

Using Blume's stochastic model and the approach of Winkler and Gerdau, we have computed-time-dependent effects on perturbed angular correlation (PAC) spectra due to defect motion in solids in the case of I = (5/2) electric quadrupole interactions. We report detailed analysis for a family of simple models: XYZ + Z'' models, in which the symmetry axis of an axial efg is allowed to fluctuate among orientations along x, y, and z axes, and a static axial efg oriented along the z axis is added to the fluctuating efgs. When the static efg is zero, this model is termed the XYZ'' model. Approximate forms are given for G{sub 2}(t) in the slow and rapid fluctuation regimes, i.e. suitable for the low and high temperature regions, respectively. Where they adequately reflect the underlying physical processes, these expressions allow one to fit PAC data for a wide range of temperatures and dopant concentrations to a single model, thus increasing the uniqueness of the interpretation of the defect properties. Application of the models are given for zirconia and ceria ceramics. 14 refs.
Date: January 1, 1990
Creator: Evenson, W. E.; Gardner, J. A.; Wang, Ruiping; Su, Han-Tzong & McKale, A. G.
System: The UNT Digital Library
PAC (perturbed angular correlation) perturbation factor for spin 5/2 nuclei subject to a rapidly fluctuation EFC (electric field gradient) (open access)

PAC (perturbed angular correlation) perturbation factor for spin 5/2 nuclei subject to a rapidly fluctuation EFC (electric field gradient)

We report numerical computations of the PAC perturbation factor G{sub 2}(t) for spin 5/2 nuclei subject to a static EFG symmetric about the z-axis and an additional axially-symmetric EFG hose symmetry axis fluctuates randomly among the x,y,z directions. For sufficiently large fluctuation rates, the numerical results are described by the expression for the static interaction alone with the addition of relaxation terms. Results of applying this model to {sup 111}Cd TDPAC measurements on tetragonal ZrO{sub 2} are described briefly. The model allows one to evaluate the probability that oxygen vacancies are trapped, the energy of association of vacancy-metal pairs, and the vacancy activation energy of motion. 4 refs., 3 figs.
Date: January 1, 1990
Creator: Evenson, W. E.; McKale, A. G.; Su, H. T. & Gardner, J. A.
System: The UNT Digital Library
Phase behavior of coal fluids: Data for correlation development (open access)

Phase behavior of coal fluids: Data for correlation development

The effective design and operation of processes for conversion of coal to fluid fuels requires accurate knowledge of the phase behavior of the fluid mixtures encountered in the conversion process. The overall objective of the author's work is to develop accurate predictive methods for representation of vapor-liquid equilibria in systems encountered in coal conversion processes. The objectives of the present project include: (1) measurements of binary vapor-liquid phase behavior data for selected solute gases (e.g. CO{sub 2} and C{sub 2}H{sub 6}) in a series of heavy hydrocarbon solvents to permit evaluation of interaction parameters in models for phase behavior, (2) measurements on ternary systems in which high-melting-point solvents are dissolved in more volatile aromatics to provide mixed solvents, (3) evaluation of existing equations-of-state and other models for representation of phase behavior in systems of the type studied experimentally; development of new correlation frameworks as needed, and (4) generalization of the interaction parameters for the solutes studied to a wide spectrum of heavy solvents; presentations of final results in formats useful in the design/optimization of coal liquefaction processes. This quarter, our framework for correlating saturation properties using a scaled-variable-reduced-coordinate'' approach was further developed to provide for generalized vapor pressure predictions. 59 …
Date: January 1, 1990
Creator: Robinson, R. J., Jr.; Gasem, K. A. M. & Shaver, R. D.
System: The UNT Digital Library
Geometric effects in tomographic reconstruction (open access)

Geometric effects in tomographic reconstruction

In x-ray and ion-beam computerized tomography, there are a number of reconstruction effects, manifested as artifacts, that can be attributed to the geometry of the experimental setup and of the object being scanned. In this work, we will examine four geometric effects that are common to first-and third-generation (parallel beam, 180 degree) computerized tomography (CT) scanners and suggest solutions for each problem. The geometric effects focused on in this paper are: X-pattern'' artifacts (believed to be caused by several errors), edge-generated ringing artifacts (due to improper choice of the reconstruction filter and cutoff frequency), circular-ring artifacts (caused by employing uncalibrated detectors), and tuning-fork artifacts (generated by an incorrectly specified center-of-rotation). Examples of four effects are presented. The X-pattern and edge-generated ringing artifacts are presented with actual experimental data introducing the artifact. given the source of the artifact, we present simulated data designed to replicate the artifact. Finally, we suggest ways to reduce or completely remove these artifacts. The circular-ring and tuning-fork artifacts are introduced with actual experimental data as well, while digital signal processing solutions are employed to remove the artifacts from the data. 15 refs., 12 figs.
Date: January 8, 1990
Creator: Barnes, F. L.; Azevedo, S. G.; Martz, H. E., Jr.; Roberson, G. P.; Schneberk, D. J. & Skeate, M. F.
System: The UNT Digital Library
Studies of the formation, chemical reactivity, and properties of small clusters: Application to an understanding of aerosol formation and heterogeneous chemistry (open access)

Studies of the formation, chemical reactivity, and properties of small clusters: Application to an understanding of aerosol formation and heterogeneous chemistry

The small cluster program involves (1) studies of reactions related to formation and growth of heteromolecular clusters and their thermochemical properties, (2) studies of photoinitiated processes in clusters, (3) investigations related to heterogeneous reactions including the influence of reaction centers on the interconversion, and (4) theoretical calculations of properties, dynamics, and structure. A major thrust of the work during the past year has been devoted to a study of the role of ionization and the presence of ions on reactions and energetics. During the past few months, particular attention has been paid to systems having varying proton affinities. From the data, we can determine the influence of these values on the nature of the reactions and ascertain the ultimate chemical nature of the ionization center formed as a result of the reactions. 83 refs., 12 figs., 2 tabs.
Date: January 1, 1990
Creator: Castleman, A. W., Jr.
System: The UNT Digital Library