Physical characterization of magmatic liquids. [Ultrasonic and Brillouin Scattering Studies of Natural and Synthetic Silicates and Oxides] (open access)

Physical characterization of magmatic liquids. [Ultrasonic and Brillouin Scattering Studies of Natural and Synthetic Silicates and Oxides]

This report describes a research project that was conducted from August 15, 1985 to February 28, 1992. The project was based on the ultrasonic studies of natural and synthetic silicate melts, and the study of Brillouin scattering of synthetic silicates and oxides. Measurements of the compressional wave velocity and attenuation can be established using the ultrasonic methods. Temperature dependences of silicates can be established by the Brillouin scattering. (MB)
Date: June 5, 1992
Creator: Manghnani, M.H.
Object Type: Report
System: The UNT Digital Library
High beta and second stability region transport and stability analysis (open access)

High beta and second stability region transport and stability analysis

This document describes ideal and resistive MHD studies of high-beta plasmas and of the second stability region. Significant progress is reported on the resistive stability properties of high beta poloidal supershot'' discharges. For these studies initial profiles were taken from the TRANSP code which is used extensively to analyze experimental data. When an ad hoc method of removing the finite pressure stabilization of tearing modes is implemented it is shown that there is substantial agreement between MHD stability computation and experiment. In particular, the mode structures observed experimentally are consistent with the predictions of the resistive MHD model. We also report on resistive stability near the transition to the second region in TFTR. Tearing modes associated with a nearby infernal mode may explain the increase in MHD activity seen in high beta supershots and which impede the realization of Q{approximately}1. We also report on a collaborative study with PPPL involving sawtooth stabilization with ICRF.
Date: September 5, 1991
Creator: unknown
Object Type: Report
System: The UNT Digital Library
In-Home Performance of Exempt Pellet Stoves in Medford, Oregon. (open access)

In-Home Performance of Exempt Pellet Stoves in Medford, Oregon.

Pellet stoves that are considered exempt'' operate at an air-to-fuel ratio in excess of 35:1. They therefore qualify for exemption from the emissions certification process. A primary goal of this project was to determine how a sample of such stoves, operated in homes, would perform compared to their certified cousins,'' which were evaluated the previous year. In-home performance data documenting emissions from exempt stoves and net delivered efficiencies was particularly desired. This project evaluated six pellet stoves representing three major brands in Medford, Oregon. There were three Breckwell model P24FS, one Horizon Eclipse, one Horizon Destiny, and one Earth Stove TP40. The stoves were monitored for four week-long intervals in January and February 1991, for a total of 24 tests. Evaluations were conducted for particulate, CO (carbon monoxide) and PAH (polycyclic aromatic hydrocarbon) emissions and net efficiency. Monitoring was conducted using the AWES (automated woodstove emissions sampler) sampling system. A new data logger, developed for this project, was used to control the AWES and record real time data. 22 refs., 17 figs., 6 tabs.
Date: July 5, 1991
Creator: Barnett, Stockton G. & Fields, Paula G.
Object Type: Report
System: The UNT Digital Library
ARM tropical pacific experiment (ATPEX): Role of cloud, water vapor and convection feedbacks in the coupled ocean/atmosphere system (open access)

ARM tropical pacific experiment (ATPEX): Role of cloud, water vapor and convection feedbacks in the coupled ocean/atmosphere system

We have initiated studies that include radiation model validation, improved treatment of the three-dimensional structure of cloud-radiation interactions, and sensitivity runs that will unravel the role of cloud-convection-radiation interactions in the Pacific Sear Surface Temperatures and the overlying Walker and Hadley circulation. The research program is divided into three phases: (1) radiation, (2) cloud parameterization issues; (3) feedback and ocean-atmosphere interactions.
Date: March 5, 1992
Creator: Ramanathan, V. & Barnett, T.P.
Object Type: Report
System: The UNT Digital Library
Readily implemented enhanced sinusoid detection in noise (open access)

Readily implemented enhanced sinusoid detection in noise

Significant efforts have been devoted, spanning many years, to the problem of sinusoid detection in noise. Many of these efforts have produced superb, yet complex, algorithms which may be difficult to use for a wide segment of the Digital Signal Processing (DSP) community. This paper presents a simple, easily implemented and high effective method which solves this problem. This method severely degrades non-sinusoidal noise while leaving the embedded sinusoid(s) relatively undisturbed. The algorithm, simply put, exploits the difference between the net effect of integration and differentiation of sinusoids versus the effect of these operations on random noise and other signal sequences. The cross-correlation of sine wave with its differentiated (and/or integrated) self is quite high. Conversely, the cross-reduction of a noise sequence with its differentiated (and/or integrated) self is much lower. Therefore, it is reasonable to assume that for sequences consisting of a sinusoid in noise, significant signal-to-noise-ratios (SNRs) in the correlation results are achievable using a combination of differentiation (and/or integration) and cross-correlation operations on such sequences. This technique has been applied to actual Doppler radar data, as well as to synthesized data, with excellent improvement in signal detection capability. 4 refs.
Date: March 5, 1992
Creator: Lindsay, K.V.
Object Type: Report
System: The UNT Digital Library
Mechanisms of defect production and atomic mixing in high energy displacement cascades: A molecular dynamics study (open access)

Mechanisms of defect production and atomic mixing in high energy displacement cascades: A molecular dynamics study

We have performed molecular dynamics computer simulation studies of displacement cascades in Cu at low temperature. For 25 keV recoils we observe the splitting of a cascade into subcascades and show that cascades in Cu may lead to the formation of vacancy and interstitial dislocation loops. We discuss a new mechanism of defect production based on the observation of interstitial prismatic dislocation loop punching from cascades at 10 K. We also show that below the subcascade threshold, atomic mixing in the cascade is recoil-energy dependent and obtain a mixing efficiency that scales as the square root of the primary recoil energy. 44 refs., 12 figs.
Date: June 5, 1991
Creator: Diaz de la Rubia, T. & Guinan, M.W.
Object Type: Article
System: The UNT Digital Library
Ductile-Brittle Transition Temperature testing of tungsten using the three-point bend test (open access)

Ductile-Brittle Transition Temperature testing of tungsten using the three-point bend test

Three-point bend tests were performed to determine the Ductile-Brittle Transition Temperatures (DBTTs) of forged and chemical vapor deposition (CVD) tungsten. Testing was performed under quasi-static conditions at temperatures between 23{degrees}C and 450{degrees}C using a forced-air environmental chamber. Load-displacement data from the three-point bend tests indicated that the constitutive behavior of the materials tested varied considerably. Finite element modeling of the three-point bend test was performed to investigate plastic strains induced in the samples during testing as a function of constitutive behavior. The modeling assumed plane stress conditions in the sample and simple bi-linear elastic-plastic constitutive behavior of the test material. The strains induced in the samples were found to be functions of both the yield stress and work hardening behavior of the materials. The use of the three-point bend test to determine DBTT, and the DBTTs reported for the test materials, are discussed relative to the modeling results. It is concluded that the three-point bend test has some utility in the determination of DBTTs if some caution is used in the selection of test parameters and fixture geometries. However, the three-point bed test does not provide a complete picture of the nature of the ductile-brittle transition. 12 refs., 9 figs.
Date: March 5, 1991
Creator: Lassila, D.H.; Magness, F. & Freeman, D.
Object Type: Report
System: The UNT Digital Library
Effects of doping on hybridization gapped materials (open access)

Effects of doping on hybridization gapped materials

Doping studies are presented on three materials exhibiting hybridization gaps: Ce{sub 3}Bi{sub 4}Pt{sub 3}, U{sub 3}Sb{sub 4}Pt{sub 3}, and CeRhSb. In the case of trivalent La, Y, or Lu substituting for Ce or U, there is a suppression of the low temperature gap and an increase in the electronic specific heat, {gamma}. In the case of tetravalent Th substitutions for U there is no change in {gamma} and in the case of tetravalent Zr substitution for Ce in CeRhSb, there is an enhanced semiconductor-like behavior in the electrical resistance. These results are discussed in the light of a simple model of hybridization gapped systems. 12 refs., 3 figs.
Date: June 5, 1991
Creator: Canfield, P. C.; Thompson, J. D.; Hundley, M. F.; Lacerda, A. & Fisk, Z.
Object Type: Article
System: The UNT Digital Library
Cedar Project---Original goals and progress to date (open access)

Cedar Project---Original goals and progress to date

This report describes: Cedar System Hardware; Compiler and Software Issues on Memory Management; Operating Systems; Compilers; and Multiprocessor Performance on Algorithms and Applications.
Date: September 5, 1991
Creator: Cybenko, G.; Kuck, D.; Padua, D. & Gallopoulos, E.
Object Type: Report
System: The UNT Digital Library
A computer system for access to distributed genome mapping data (open access)

A computer system for access to distributed genome mapping data

Development of a computer system for access to distributed genome mapping data is continuing. This effort is to develop software which accesses multiple databases and retrieves data which contain information useful for accelerating mapping human chromosomes. For example, the molecular sequence databases (GenBank, EMBL Data Library, PIR, SwissProt) which contain data required for the development of oligonucleotides for probing DNA as well as for extracting data for primer pair development for PCR-based methods. It is also to develop software which qualitatively integrates the following mapping data: (1) markers regionally localized using cytogenetic methods, (2) polymorphic markers ordered by genetic linkage analysis, (3) clones ordered by various finger-printing'' methods, (4) fragments ordered by long-range restriction mapping, (5) single genomic fragments or clones that have STSs assigned to them, (6) nucleotide sequences, (7) the associated metadata such as the submitting investigator's name, location, etc; the source organism; the chromosome the element is from; the chromosomal location is whatever detail is available.
Date: February 5, 1992
Creator: Marr, T.G.
Object Type: Report
System: The UNT Digital Library
Reactor Operations Management Plan (open access)

Reactor Operations Management Plan

The K-Reactor last operated in April 1988. At that time, K-Reactor was one of three operating reactors at the Savannah River Site (SRS). Following an incident in P-Reactor in August 1988, it was decided to discontinue SRS reactor operation and conduct an extensive program to upgrade operating practices and plant hardware prior to restart of any of the reactors. The K-reactor was the first of three reactors scheduled to resume production. At the present time, it is the only reactor with planned restart. WSRC assumed management of SRS on April 1, 1989. WSRC established the Safety Basis for Restart and a listing of the actions planned to satisfy the Safety Basis. In consultation with DOE, it was determined that proper management of the restart activities would require a single plan that integrated the numerous activities. The plan was entitled the Reactor Operations Management Plan and is referred to simply as the ROMP. The initial version of ROMP was produced in July of 1989. Subsequent modifications led to Revision 3 which was approved by DOE in May, 1990. Other changes were made in a formal change process, resulting in the latest version, Revision 5, being issued in October, 1990. The ROMP …
Date: December 5, 1991
Creator: Rice, P.D.
Object Type: Article
System: The UNT Digital Library
Exploratory coprocessing research (open access)

Exploratory coprocessing research

The objectives of this project were to (1) study the scope of the beneficial effects of hydrothermal pretreatment of coal on subsequent conversion, (2) identify and study the chemical or physical causes of this effect, and (3) attempt to elucidate the chemistry responsible for any coal-resid synergisms.
Date: September 5, 1991
Creator: Hirschon, A. S.; Tse, D. S.; Malhotra, R.; McMillen, D. F. & Ross, D. S.
Object Type: Report
System: The UNT Digital Library
(Acid rain workshop) (open access)

(Acid rain workshop)

The traveler presented a paper entitled Susceptibility of Asian Ecosystems to Soil-Mediated Acid Rain Damage'' at the Second Workshop on Acid Rain in Asia. The workshop was organized by the Asian Institute of Technology (Bangkok, Thailand), Argonne National Laboratory (Argonne, Illinois), and Resource Management Associates (Madison, Wisconsin) and was sponsored by the US Department of Energy, the United Nations Environment Program, the United Nations Economic and Social Commission for Asia and the Pacific, and the World Bank. Papers presented on the first day discussed how the experience gained with acid rain in North America and Europe might be applied to the Asian situation. Papers describing energy use projections, sulfur emissions, and effects of acid rain in several Asian countries were presented on the second day. The remaining time was allotted to discussion, planning, and writing plans for a future research program.
Date: December 5, 1990
Creator: Turner, R. S.
Object Type: Report
System: The UNT Digital Library
Some limitations of detailed balance for inverse reaction calculations in the astrophysical p-process (open access)

Some limitations of detailed balance for inverse reaction calculations in the astrophysical p-process

p-Process modeling of some rare but stable proton-rich nuclei requires knowledge of a variety of neutron, charged particle, and photonuclear reaction rates at temperatures of 2 to 3 {times} 10{sup 9} {degrees}K. Detailed balance is usually invoked to obtain the stellar photonuclear rates, in spite of a number of well-known constraints. In this work we attempt to calculate directly the stellar rates for ({gamma},n) and ({gamma},{alpha}) reactions on {sup 151}Eu. These are compared with stellar rates obtained from detailed balance, using the same input parameters for the stellar (n,{gamma}) and ({alpha},{gamma}) reactions on {sup 150}Eu and {sup 147}Pm, respectively. The two methods yielded somewhat different results, which will be discussed along with some sensitivity studies. 16 refs., 7 figs.
Date: December 5, 1990
Creator: Gardner, D. G. & Gardner, M. A.
Object Type: Article
System: The UNT Digital Library
Time response of fast-gated microchannel plates used as x-ray detectors (open access)

Time response of fast-gated microchannel plates used as x-ray detectors

We report measurements of the time response of fast-gated, micro- channel plate (MCP) detectors, using a <10 ps pulsewidth ultra-violet laser and an electronic sampling system to measure time resolutions to better than 25 ps. The results show that framing times of less than 100 ps are attainable with high gain. The data is compared to a Monte Carlo calculation, which shows good agreement. We also measured the relative sensitivity as a function of DC bias, and saturation effects for large signal inputs. In part B, we briefly describe an electrical time-of-flight'' technique, which we have used to measure the response time of a fast-gated microchannel plate (MCP). Thinner MCP's than previously used have been tested, and, as expected, show fast gating times and smaller electron multiplication. A preliminary design for an x-ray pinhole camera, using a thin MCP, is presented. 7 refs., 6 figs.
Date: November 5, 1990
Creator: Turner, R. E.; Bell, P.; Hanks, R.; Kilkenny, J. D.; Landen, N.; Power, G. et al.
Object Type: Article
System: The UNT Digital Library
Modal study of refractive effects on x-ray laser coherence (open access)

Modal study of refractive effects on x-ray laser coherence

The role of smoothly varying transverse gain and refraction profiles on x-ray laser intensity and coherence is analyzed by modally expanding the electric field within the paraxial approximation. Comparison with a square transverse profile reveals that smooth-edged profiles lead to: (1) a greatly reduced number of guided modes, (2) the continued cancellation of local intensity from a loosely guided mode by resonant free modes, (3) and the absence of extraneous (or anomalous) free mode resonances. These generic spectral properties should enable a considerable simplification in analyzing and optimizing the coherence properties of laboratory soft x-ray lasers. 6 refs., 3 figs.
Date: April 5, 1991
Creator: Amendt, P.; London, R.A. (Lawrence Livermore National Lab., CA (USA)) & Strauss, M. (Israel Atomic Energy Commission, Beersheba (Israel). Nuclear Research Center-Negev)
Object Type: Article
System: The UNT Digital Library
Star-disk collisions in active galactic nuclei and the origin of the broad line region (open access)

Star-disk collisions in active galactic nuclei and the origin of the broad line region

Stars of a cluster surrounding the central black hole in an AGN will collide with the accretion disk. For a central black hole of 10{sup 8} M{circle dot} and a cluster with 10{sup 7} {minus} 10{sup 8} stars within a parsec, one estimates that {approximately}10{sup 4} such collisions will occur per year. Collisions are hypersonic (Mach number M {much gt} 1). Some of the wake of the star -- the disk material shocked by its passage -- will follow it out of the disk. Such star tails'' with the estimated masses {delta}m {approximately} 10{sup 25} {minus} 10{sup 27} g subsequently expand, cool and begin to recombine. We propose that -- when illuminated by the ionizing flux from the central source -- they are likely to be the origin of the observed broad emission lines.
Date: December 5, 1991
Creator: Zurek, W.H.; Colgate, S.A. (Los Alamos National Lab., NM (United States)) & Siemiginowska, A. (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States))
Object Type: Article
System: The UNT Digital Library
Practical path planning among movable obstacles (open access)

Practical path planning among movable obstacles

Path planning among movable obstacles is a practical problem that is in need of a solution. In this paper an efficient heuristic algorithm that uses a generate-and-test paradigm: a good'' candidate path is hypothesized by a global planner and subsequently verified by a local planner. In the process of formalizing the problem, we also present a technique for modeling object interactions through contact. Our algorithm has been tested on a variety of examples, and was able to generate solutions within 10 seconds. 5 figs., 27 refs.
Date: September 5, 1990
Creator: Chen, Pang C. & Hwang, Yong K.
Object Type: Article
System: The UNT Digital Library
From bit-strings (part way) to quaternions (open access)

From bit-strings (part way) to quaternions

We present work in progress on constructing rotations and boosts from bit strings, and a mapping of bit-strings onto integer quaternion coordinates.
Date: April 5, 1991
Creator: Noyes, H. Pierre
Object Type: Article
System: The UNT Digital Library
Estimating deposition velocity from atmospheric releases of iodine (open access)

Estimating deposition velocity from atmospheric releases of iodine

Deposition velocity is a parameter used in atmospheric transport models to specify the amount an atmospheric constituent transferred from the atmosphere to the surface of the earth. The material may deposit on the surface of soil, water, or vegetation. The deposition may be the result of rainfall or diffusion. A method for the calculation of deposition velocity based upon the decrease in deposition with distance from a point source is presented. The method does not require a knowledge of the time over which the deposition occurs or the concentration of the material in the atmosphere. However, the method does assume the deposition rate is proportional to the air concentration. The sensitivity to errors resulting from certain errors in the measurements and from violation of some of the assumptions of the model underlining the calculations are also to be discussed. The method has been used to estimate the deposition velocity of I-129. Two sets of I-129 deposition data at various distances from the center of SRS were used in the calculations. The results indicate that the deposition velocity is near a value of 0.2 cm/s. This is consistent with the processes that are known to control iodine deposition.
Date: February 5, 1991
Creator: Murphy, C. E. Jr.
Object Type: Report
System: The UNT Digital Library
Magnetic design for the ATF beamline. number sign. 1 (open access)

Magnetic design for the ATF beamline. number sign. 1

This report gives a self-consistent conceptual design for the final focusing'' beam optics and analysis spectrometer optics for the Grating Acceleration Experiment, the Inverse Cerenkov Acceleration Experiment, and the Nonlinear Compton Scattering Experiment. The introductory section describes the basic principles and constraints involved in the overall design. The next two sections give second order TRANSPORT calculations for the final focus system and the spectrometer system for the three experiments. The fourth section presents Monte Carlo simulations of the expected x-y distributions for the spectrometer detector for the three experiments. Appendices A and B contains further details about the assumptions used in the Monte Carlo simulations. Appendix C contains the working drawings used for determining distances on the experimental floor.
Date: February 5, 1992
Creator: Fernow, R.C.
Object Type: Report
System: The UNT Digital Library
A recommendation: How to build lasting consensus on a national energy strategy (open access)

A recommendation: How to build lasting consensus on a national energy strategy

The objective of the Consensus Building process for a national energy strategy would be to generate several concrete products, including: (1) An inventory of possible packages which could represent acceptable energy strategies for most key constituencies in developing a fair, efficient wise, and sustainable national energy policy; (2) An inventory of strategic dead ends and policy positions that could generate fierce opposition from specific stakeholding groups if they emerge as part of the eventual strategy, absent compensating trade offs; and, (3) An inventor of the interests and assumptions of the many opposing constituencies. The process would be a sophisticated proving ground where collaborative problem solving techniques could be applied and evaluated. This report in the American Energy Assurance Council's 12-step recommendation for consensus building. They recommend an eight-month timeframe for this project, although they recognize that many interested parties may perceive this as too long. If a shorter timeframe is required, these 12 steps could be time compressed and still produce meaningful results.
Date: November 5, 1990
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Research accomplishments and future goals in particle physics (open access)

Research accomplishments and future goals in particle physics

This document presents our proposal to continue the activities of Boston University researchers in eight projects in high energy physics research: Colliding Beams Physics; Accelerator Design Physics; MACRO Project; Proton Decay Project; Theoretical Particle Physics; Muon G-2 Project; and Hadron Collider Physics. The scope of each of these projects is presented in detail in this paper.
Date: January 5, 1990
Creator: Whitaker, J.S.
Object Type: Report
System: The UNT Digital Library
Confined zone dispersion flue gas desulfurization demonstration (open access)

Confined zone dispersion flue gas desulfurization demonstration

The CZD process involves flue gas post-treatment, physically located between a boiler's outlet and its particulate collector, which in the majority of cases is an electrostatic precipitator. The features that distinguish this process from other similar injection processes are: Injection of an alkaline slurry directly into the duct, instead of injection of dry solids into the duct ahead of a fabric filter. Use of an ultrafine calcium/magnesium hydroxide, type S pressure-hydrated dolomitic lime. This commercial product is made from plentiful, naturally occurring dolomite. Low residence time, made possibly by the high effective surface area of the type S lime. Localized dispersion of the reagent. Slurry droplets contact only part of the gas while the droplets are drying, to remove up to 50 percent of the SO{sub 2} and significant amounts of NO{sub x}. The process uses dual fluid rather than rotary atomizers. Improved ESP performance via gas conditioning from the increased water vapor content, and lower temperatures. Supplemental conditioning with SO{sub 3} is not believed necessary for satisfactory removal of particulate matter. The waste product is composed of magnesium and calcium sulfite and sulfate, with some excess lime. This product mixed with fly ash is self-stabilizing because of the excess …
Date: September 5, 1991
Creator: unknown
Object Type: Report
System: The UNT Digital Library