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1,177 Matching Results
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Wind loads on heliostats and parabolic dish collectors: Final subcontractor report
A major intent of this study was to define wind load reduction factors for parabolic dish solar collectors within a field protected by upwind collectors, wind protective fences, or other blockages. This information will help researchers improve the economy of parabolic collector support structures and drive mechanisms. The method used in the study was to generalize wind load data obtained during tests on model collectors placed in a modeled atmospheric wind in a boundary-layer wind tunnel. A second objective of the study was to confirm and document a sensitivity in load to level of turbulence, or gustiness, in the approaching wind. A key finding was that wind-load reduction factors for forces (horizontal and vertical) were roughly similar to those for flat heliostats, with some forces significantly less than those for flat shapes. However, load reductions for moments showed a smaller load reduction, particularly for the azimuth moment. The lack of load reduction could be attributed to collector shape, but specific flow features responsible for and methods to induce a load reduction were not explored. 62 figs., 13 tabs.
Date:
November 1, 1988
Creator:
Peterka, J. A.; Tan, Z.; Bienkiewicz, B. & Cermak, J. E.
Object Type:
Report
System:
The UNT Digital Library
Some comments on the interaction of fast-neutrons with beryllium
Neutron total cross sections of elemental beryllium were measured from 1 to > 10 MeV with good precision. Differential neutron elastic-scattering cross sections were measured from 4.5 to 10 MeV at energy intervals of approx.0.5 MeV, and for approx. 100 angular steps distributed between 18/degree/ and 160/degree/ at each incident energy. Concurrently, differential cross sections for the emission of a discrete inelastic-neutron group corresponding to an excited level at 2.43 +- 0.06 MeV were determined over the same incident-energy and angular range. Angle-integrated elastic-scattering cross sections were deduced from the observed differential values to accuracies of 2.5%, and angle-integrated inelastic-scattering cross sections were established to accuracies of less than or equal to 10%. The experimental results are compared with values given in ENDF/B-V, with attention to discrepancies and implications. Qualitative reaction mechanisms are suggested. 27 refs., 8 figs., 1 tab.
Date:
November 1, 1988
Creator:
Sugimoto, M.; Guenther, P. T.; Lynn, J. E.; Smith, A. B. & Whalen, J. F.
Object Type:
Report
System:
The UNT Digital Library
Study of semiconductor valence plasmon line shapes via electron energy-loss spectroscopy in the transmission electron microscope
Electron energy-loss spectra of the semiconductors Si, AlAs, GaAs, InAs, InP, and Ge are examined in detail in the regime of outer-shell and plasmon energy losses (0--100eV). Particular emphasis is placed on modeling and analyzing the shapes of the bulk valence plasmon lines. A line shape model based on early work by Froehlich is derived and compared to single-scattering probability distributions extracted from the measured spectra. Model and data are found to be in excellent agreement, thus pointing the way to systematic characterization of the plasmon component of EELS spectra. The model is applied to three separate investigations. 82 refs.
Date:
November 1, 1988
Creator:
Kundmann, M.K.
Object Type:
Report
System:
The UNT Digital Library
Effect of the coherent cancellation of the two-photon resonance on the generation of vacuum ultraviolet light by two-photon reasonantly enhanced four-wave mixing
Many of the most impressive demonstrations of the efficient generation of vacuum ultraviolet (VUV) light have made use of two- photon resonantly enhanced four-wave mixing to generate light at ..omega../sub VUV/ = 2..omega../sub L1/ +- ..omega../sub L2/. The two-photon resonance state is coupled to the ground state both by two photons from the first laser, or by a photon from the second laser and one from the generated VUV beam. We show here that these two coherent pathways destructively interfere once the second laser is made sufficiently intense, thereby leading to an important limiting effect on the achievable conversion efficiency. 4 refs.
Date:
November 1, 1988
Creator:
Payne, M. G.; Garrett, W. R.; Judish, J. P. & Wunderlich, R.
Object Type:
Article
System:
The UNT Digital Library
Final focus system for TLC
A limit of the chromaticity correction for the final focus system of a TeV Linear Collider (TLC) is investigated. As the result, it becomes possible to increase the aperture of the final doublet with a small increase of the horizontal US function. The new optics design uses a final doublet of 0.5 mm half-aperture and 1.4 T pole-tip field. The length of the system is reduced from 400 m to 200 m by several optics changes. Tolerances for various machine errors with this optics are also studied. 5 refs., 7 figs., 2 tabs.
Date:
November 1, 1988
Creator:
Oide, K.
Object Type:
Article
System:
The UNT Digital Library
Preliminary report on the MBE-4, an experimental multiple-beam induction linear accelerator for heavy ions
A small-scale experimental accelerator called MBE-4 has been constructed to demonstrate the principle of a current-amplifying induction linac for multiple beams of heavy ions. Four beams of Cs{sup 1+}, initially at 200 keV and each with a current of 10 mA have been accelerated and amplified to a kinetic energy of 700 keV and currents of 90 mA apiece. Transverse focusing is achieved by means of electrostatic quadrupoles; longitudinally the current is amplified and the beam bunch is held together against the space charge forces by special time-dependent accelerating fields. We report on the methods developed for designing and implementing the accelerating pulses and on measurements of the transverse and longitudinal emittance of the accelerated beams. Current fluctuations and the longitudinal emittance are initially almost zero and increase as acceleration errors are accumulated. We discuss the final longitudinal emittance and the current fluctuations in the experiment in terms of their acceptability for a large heavy-ion-fusion driver. 17 refs., 23 figs., 3 tabs.
Date:
November 1, 1988
Creator:
Warwick, A. I.; Gough, D. E. & Meuth, H.
Object Type:
Report
System:
The UNT Digital Library
Two-photon resonant, stimulated processes in krypton and xenon
Both on-axis and conical emissions have been observed following two-photon pumping of the 5p states of krypton and the 6p', 7p, 8p, and 4f states of xenon. In the former case, coherent emissions from the 5p states to the 5s are observed, and in the latter case, many p..-->..s, d..-->..p, and f..-->..d cascade emissions are observed. By analogy to the well-studied alkali and alkaline earth examples, the emissions are discussed in terms of amplified spontaneous emission (ASE), stimulated hyper-Raman scattering, and parametric four-wave mixing. The physical processes responsible for the conical emission and for intensity anomalies in the xenon p..-->..s emissions are not understood at present. Interference effects due to coherent cancellation between competing excitation pathways may be occurring. 4 refs., 3 figs.
Date:
November 1, 1988
Creator:
Miller, J. C.
Object Type:
Article
System:
The UNT Digital Library
A two-dimensional particle simulation of the magnetopause current layer
We have developed a 2/1/2/-D (x, y, v/sub x/, v/sub y/, v/sub z/) electromagnetic code to study the formation and the stability of the magnetopause current layer. This code computes the trajectories of ion and electron particles in their self-consistently generated electromagnetic field and an externally imposed 2-D vacuum dipolar magnetic field. The results presented here are obtained for the simulation of the solar wind-magnetosphere interaction in the subsolar region of the equatorial plane. We observe the self-consistent establishment of a current layer resulting from both diamagnetic drift and E /times/ B drift due to the charge separation. The simulation results show that during the establishment of the current layer, its thickness is of the order of the hybrid gyroradius /rho//sub H/ = ..sqrt../rho//sub i//rho//sub e/ predicted by the Ferraro-Rosenbluth model. However, diagnostics indicate that the current sheet is subject to an instability which broadens the width of the current layer. Ripples with amplitudes of the order of the ion gyroradius appear at the interface between the field and the particles. These pertubations are observed both on the electrostatic field and on the compressional component of the magnetic field. This instability has a frequency of the order of the local …
Date:
November 1, 1988
Creator:
Berchem, J. & Okuda, H.
Object Type:
Report
System:
The UNT Digital Library
Analysis of the accidental explosion at Pepcon, Henderson, Nevada, May 4, 1988
Several hours of fire and numerous explosions destroyed the Pacific Engineering Company plant in Henderson, Nevada, that manufactured ammonium perchlorate (AP) for rocket fuel. This incident began about 1130 PDT on May 4, 1988, with a fire in their Batch House that grew out of control and caused a first large explosion at about 1153 PDT. The final and largest explosion occurred about 1157 PDT. Damages to the surrounding community were surveyed and interpreted as airblast overpressures versus distances, which allowed an estimate of 1-kiloton nuclear free-air-burst for the equivalent explosion yield. This could be reproduced by 250-tons TNT burst on the ground surface. Weather reports were obtained from the National Weather Services which indicated somewhat enhanced airblast propagation downwind toward northerly directions and attenuated airblast propagations upwind in southerly directions. It was impossible, for lack of winds aloft information below about 500 m above ground, to determine whether there was any atmospheric acoustic airblast focusing. Several seismic recordings in Las Vegas showed the greatest ground motion resulted from the airblast wave passage, traveling at near acoustic speed. Ground wave arrival times were not sufficiently precise to allow seismic speed interpretations. Of the 4000 tons of AP apparently stored in …
Date:
November 1, 1988
Creator:
Reed, J. W.
Object Type:
Report
System:
The UNT Digital Library
Prospects at high energies
I discuss some possibilities for neutrino experiments in the fixed-target environment of the SPS, Tevatron, and UNK, with their primary proton beams of 0.4, 0.9, and 3.0 TeV. The emphasis is on unfinished business: issues that have been recognized for some time, but not yet resolved. Then I turn to prospects for proton-proton colliders to explore the 1-TeV scale. I review the motivation for new physics in the neighborhood of 1 TeV and mention some discovery possibilities for high-energy, high-luminosity hadron colliders and the implications they would have for neutrino physics. I raise the possibility of the direct study of neutrino interactions in hadron colliders. I close with a report on the status of the SSC project. 38 refs., 17 figs.
Date:
November 1, 1988
Creator:
Quigg, C.
Object Type:
Article
System:
The UNT Digital Library
Localized corrosion and stress corrosion cracking of candidate materials for high-level radioactive waste disposal containers in the US: A literature review
Container materials may undergo any of several modes of degradation in this environment, including: undesirable phase transformations due to lack of phase stability; atmospheric oxidation; general aqueous corrosion; pitting; crevice corrosion; intergranular stress corrosion cracking (IGSCC); and transgranular stress corrosion cracking (TGSCC). This paper is an analysis of data from the literature relevant to the pitting, crevice corrosion, and stress corrosion cracking (SCC) of these alloys. Though all three austenitic candidates have demonstrated pitting and crevice corrosion in chloride-containing environments, Alloy 825 has the greatest resistance to these forms of localized attack. Both types 304L and 316L stainless steels are susceptible to SCC in acidic chloride media. In contrast, SCC has not been documented for Alloy 825 under comparable conditions. Gamma irradiation has been found to enhance SCC of Types 304 and 304L stainless steels, but it has no detectable effect on the resistance of Alloy 825 to SCC. Furthermore, while microbiologically induced corrosion effects have been observed for 300-series stainless steels, nickel-based alloys such as Alloy 825 seem to be immune to such problems. Of the copper-based alloys, CDA 715 has the best overall resistance to localized attack. Its resistance to pitting is comparable to that of CDA 613 …
Date:
November 4, 1988
Creator:
Farmer, J.C. & McCright, R.D.
Object Type:
Article
System:
The UNT Digital Library
An ALS (Advanced Light Source) handbook
This booklet aims to provide the prospective user of the Advanced Light Source with a concise description of the radiation a researcher might expect at his or her experimental station. The focus is therefore on the characteristics of the light that emerges from insertion devices and bending magnets and on how components of the beam lines further alter the properties of the radiation. The specifications and operating parameters of the ALS injection system and storage ring are of only peripheral interest. To this end, Sections 3 and 5 and most of Section 4 are devoted to summary presentations, by means of performance plots and tabular compilations, of radiation characteristics at the ALS--spectral brightness, flux, coherent power, resolution, time structure, etc.--assuming a representative set of four undulators and one wiggler and a corresponding set of five beam lines. As a complement to these performance summaries, Section 1 is a general introductory discussion of synchrotron radiation and the ALS, and Section 2 provides a compendious introduction to the characteristics of synchrotron radiation from bending magnets, wigglers, and undulators. In addition, Section 4 briefly introduces the theory of diffraction grating and crystal monochromators. 15 refs., 28 figs., 5 tabs.
Date:
November 1, 1988
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Recommended procedures for performance testing of radiobioassay laboratories: Volume 1, Quality assurance. [Contains Glossary]
Draft American National Standards Institute (ANSI) Standard N13.30 (Performance Criteria for Radiobioassay) was developed in response to a concern expressed by the US Department of Energy and US Nuclear Regulatory Commission to help ensure that bioassay laboratories provide accurate and consistent results. The draft standard specifies the criteria for defining the procedures necessary to establish a bioassay performance-testing laboratory and program. The testing laboratory will conduct tests to evaluate the performance of service laboratories. Pacific Northwest Laboratory helped define responsibilities and develop procedures as part of an effort to evaluate the draft ANSI N13.30 performance criteria for quality assurance at bioassay laboratories. This report recommends elements of quality assurance and quality control responsibilities for the bioassay performance-testing laboratory program, including the qualification and performance of personnel and the calibration, certification, and performance of equipment. The data base and recommended records system for documenting radiobioassay performance at the service laboratories are also presented. 15 refs.
Date:
November 1, 1988
Creator:
Fenrick, H.W. & MacLellan, J.A.
Object Type:
Report
System:
The UNT Digital Library
String mediated phase transitions
It is demonstrated from first principles how the existence of string like structures can cause a system to undergo a phase transition. In particular, we concentrate on the role of topologically stable cosmic string in the restoration of spontaneously broken symmetries. We discuss how the thermodynamic properties of strings alter when stiffness and nearest neighbor string-string interactions are included. 25 refs., 5 figs.
Date:
November 1, 1988
Creator:
Copeland, E.; Haws, D.; Rivers, R. & Holbraad, S.
Object Type:
Article
System:
The UNT Digital Library
GENII: The Hanford Environmental Radiation Dosimetry Software System: Volume 2, Users' Manual: Hanford Environmental Dosimetry Upgrade Project
The Hanford Environmental Dosimetry Upgrade Project was undertaken to incorporate the internal dosimetry models recommended by the International Commission on Radiological Protection (ICRP) in updated versions of the environmental pathway analysis models used at Hanford. The resulting second generation of Hanford environmental dosimetry computer codes is compiled in the Hanford Environmental Dosimetry System (Generation II, or GENII). The purpose of this coupled system of computer codes is to analyze environmental contamination of, air, water, or soil. This is accomplished by calculating radiation doses to individuals or populations. GENII is described in three volumes of documentation. This second volume is a Users' Manual, providing code structure, users' instructions, required system configurations, and QA-related topics. The first volume describes the theoretical considerations of the system. The third volume is a Code Maintenance Manual for the user who requires knowledge of code detail. It includes logic diagrams, global dictionary, worksheets, example hand calculations, and listings of the code and its associated data libraries. 27 refs., 17 figs., 23 tabs.
Date:
November 1, 1988
Creator:
Napier, B. A.; Peloquin, R. A.; Strenge, D. L. & Ramsdell, J. V.
Object Type:
Report
System:
The UNT Digital Library
Experimental studies of self-suppression of vacuum ultraviolet generation in Xe
Vacuum ultraviolet light in the range 116 nm to 117 nm was produced by using a two-photon resonant four-wave mixing scheme in Xe. The buildup of coherent cancellation of the two-photon resonant transition employed in the generation of the vacuum ultraviolet, with resulting limitations imposed on the achievable vacuum ultraviolet intensity was investigated. Under certain predicted conditions, increases in the intensity of one of the pumping beams, approx.1500 nm infrared, or tuning this beam towards resonance with the 5p/sup 5/7s(3/2)/sub 1/ level of Xe led, not to increases, but decreases in the vacuum ultraviolet generated. 3 refs., 3 figs.
Date:
November 1, 1988
Creator:
Judish, J. P.; Allman, S. L.; Garrett, W. R. & Payne, M. G.
Object Type:
Article
System:
The UNT Digital Library
The Cherokeean. (Rusk, Tex.), Vol. 140, No. 39, Ed. 1 Thursday, November 3, 1988
Weekly newspaper from Rusk, Texas that includes local, state and national news along with extensive advertising.
Date:
November 3, 1988
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
The Cherokeean. (Rusk, Tex.), Vol. 140, No. 40, Ed. 1 Thursday, November 10, 1988
Weekly newspaper from Rusk, Texas that includes local, state and national news along with extensive advertising.
Date:
November 10, 1988
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
The Cherokeean. (Rusk, Tex.), Vol. 140, No. 41, Ed. 1 Thursday, November 17, 1988
Weekly newspaper from Rusk, Texas that includes local, state and national news along with extensive advertising.
Date:
November 17, 1988
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
The Cherokeean. (Rusk, Tex.), Vol. 140, No. 42, Ed. 1 Thursday, November 24, 1988
Weekly newspaper from Rusk, Texas that includes local, state and national news along with extensive advertising.
Date:
November 24, 1988
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
The Rio Grande Herald (Rio Grande City, Tex.), No. 52, Ed. 1 Thursday, November 3, 1988
Weekly newspaper from Rio Grande City, Texas that includes local, state and national news along with extensive advertising.
Date:
November 3, 1988
Creator:
Roberts, Kenneth
Object Type:
Newspaper
System:
The Portal to Texas History
The Rio Grande Herald (Rio Grande City, Tex.), Vol. [79], No. 1, Ed. 1 Thursday, November 10, 1988
Weekly newspaper from Rio Grande City, Texas that includes local, state and national news along with extensive advertising.
Date:
November 10, 1988
Creator:
Roberts, Kenneth
Object Type:
Newspaper
System:
The Portal to Texas History
The Rio Grande Herald (Rio Grande City, Tex.), Vol. [79], No. 2, Ed. 1 Thursday, November 17, 1988
Weekly newspaper from Rio Grande City, Texas that includes local, state and national news along with extensive advertising.
Date:
November 17, 1988
Creator:
Roberts, Kenneth
Object Type:
Newspaper
System:
The Portal to Texas History
The Rio Grande Herald (Rio Grande City, Tex.), Vol. [79], No. 3, Ed. 1 Thursday, November 24, 1988
Weekly newspaper from Rio Grande City, Texas that includes local, state and national news along with extensive advertising.
Date:
November 24, 1988
Creator:
Roberts, Kenneth
Object Type:
Newspaper
System:
The Portal to Texas History