Access

Resource Type

Partner

Collection

Serial/Series Title

Degree Department

Degree Discipline

Degree Level

Country

States

Counties

Year

Month

Day

Language

34,619 Matching Results

Start Over Year 1982

Results open in a new window/tab.

prev Results: 49 - 72 of 34,619 next

(open access)

Stochastic modelling of physiologic processes with radiotracers and positron emission tomography

The compartment model, so often used in nuclear medicine and in pharmacokinetics, is formed by a set of linear differential equations of order one with constant coefficients; its validity depends upon the hypothesis that the system described contains a finite number of components, and that each component is homogeneous. These hypotheses exclude the presence of diffusion and of age-dependent processes, or in general of transport of a non-Markovian nature. The fact that frequently the experimental data agree with this model does not necessarily prove the model is appropriate, but only that it is flexible. In addition to the consistency with the experimental data, an obvious conceptual requirement of the model is that its parameters could be interpreted in terms of perceivable physical properties. All this considered, it will be demonstrated that the experimental data can be examined in terms of a model making a minimum number of assumptions and giving the best physical interpretations to the parameters involved. By way of example, a high resolution positron emission tomograph will be used to determine the successive moments describing the blood circulation through different sections of the brain. Whereever the relative moments form a geometric progression, the circulation in that section follows …

Date: January 1, 1982

Creator: Rescigno, A.; Lambrecht, R. M. & Duncan, C. C.

Object Type: Article

System: The UNT Digital Library

(open access)

Development of a procedure to estimate runoff and sediment transport in ephemeral streams

A distributed hydrologic model for application on small, semiarid watersheds is developed. The distributed model incorporates simplified routing schemes to include the influence of transmission losses on runoff. A sediment transport model, by sediment size fractions, is developed to compute transport capacity and sediment yield in noncohesive, alluvial channels. Based on available information published in soils and topographic maps and on channel and bed sediment characteristics, the procedure is used to estimate runoff rates and amounts together with sediment yields from semiarid watersheds. Example applications include flood frequency analysis and sediment yield. The procedure requires a minimum of observed data for calibration and is designed for practical applications.

Date: January 1, 1982

Creator: Lane, L.J.

Object Type: Report

System: The UNT Digital Library

(open access)

Collisionally excited few-electron systems: theoretical introduction and survey. [2-200 keV]

We consider excitation, ionization, and charge transfer in collisions of protons (and antiprotons) with the single-electron targets H, He/sup +/, and Li/sup 2 +/. These collisions are first compared to other types of ion-atom collisions. A brief review of our own theoretical method is given; in particular we describe how we allow for both large charge transfer and ionization probabilities while retaining the computational efficiency that allows us to consider a variety of collision partners and collision energies. We comment on the comparison of our results to other theoretical work and to experiment. The qualitative features of the various inelastic cross sections are discussed, in particular how they scale with collision energy, target nuclear charge, and the sign of the projectile charge. 15 references, 6 figures.

Date: January 1, 1982

Creator: Ford, A.L.; Reading, J.F. & Becker, R.L.

Object Type: Report

System: The UNT Digital Library

(open access)

Measurements of /sup 234/U, /sup 238/U and /sup 230/Th in excreta of uranium-mill crushermen

Uranium and thorium levels in excreta of uranium mill crushermen who are routinely exposed to airborne uranium ore dust were measured. The purpose was to determine whether /sup 230/Th was preferentially retained over either /sup 234/U or /sup 238/U in the body. Urine and fecal samples were obtained from fourteen active crushermen with long histories of exposure to uranium ore dust, plus four retired crushermen and three control individuals for comparison. Radiochemical procedures were used to separate out the uranium and thorium fractions, which were then electroplated on stainless steel discs and assayed by alpha spectrometry. Significantly greater activity levels of /sup 234/U and /sup 238/U were measured in both urine and fecal samples obtained from uranium mill crushermen, indicating that uranium in the inhaled ore dust was cleared from the body with a shorter biological half-time than the daughter product /sup 230/Th. The measurements also indicated that uranium and thorium separate in vivo and have distinctly different metabolic pathways and transfer rates in the body. The appropriateness of current ICRP retention and clearance parameters for /sup 230/Th in ore dust is questioned.

Date: July 1, 1982

Creator: Fisher, D. R.; Jackson, P. O.; Brodacynski, G. G. & Scherpelz, R. I.

Object Type: Report

System: The UNT Digital Library

(open access)

Is the two-term expansion valid for highly anisotropic systems. The Townsend ionization coefficient in strong runaway as a test case

The Townsend ionization coefficient in the strong runaway regime is calculated within the framework of the two-term expansion. Results are compared to the 1-D model. General features of the two models are qualitatively similar, but quantitative differences by factors of approx. 2 are observed.

Date: July 15, 1982

Creator: Yu, S. S. & Melendez, R. E.

Object Type: Report

System: The UNT Digital Library

(open access)

Locations and areas of ponds and Carolina Bays at the Savannah River Plant

The Savannah River Plant has 28 ponds and 190 Carolina Bays on its 192,000-acreite. Excluding the Par Pond system, the mean pond area is 17.6 acre, with a range of 0.4 to 202.8 acres. Par Pond is the largest pond, with an area of 2500 acres. The mean Carolina Bay area is 6.6 acres, with a range of less than 0.3 to 124.0 acres. The geographical location of each pond and bay has been digitized and can be graphically displayed by computer. This capability will facilitate identification of wetland areas as required by Executive Order 11990 (Protection of Wetlands, May 24, 1977).

Date: May 1, 1982

Creator: Shields, J. D.; Woody, N. D.; Dicks, A. S.; Hollod, G. J.; Schalles, J. & Leversee, G. J.

Object Type: Report

System: The UNT Digital Library

(open access)

Cumulative impacts study of The Geysers KGRA: public-service impacts of geothermal development

Geothermal development in The Geysers KGRA has affected local public services and fiscal resources in Sonoma, Lake, Mendocino, and Napa counties. Each of these counties underwent rapid population growth between 1970 and 1980, some of which can be attributed to geothermal development. The number of workers currently involved in the various aspects of geothermal development in The Geysers is identified. Using three different development scenarios, projections are made for the number of power plants needed to reach the electrical generation capacity of the steam resource in The Geysers. The report also projects the cumulative number of workers needed to develop the steam field and to construct, operate, and maintain these power plants. Although the number of construction workers fluctuates, most are not likely to become new, permanent residents of the KGRA counties. The administrative and public service costs of geothermal development to local jurisdictions are examined and compared to geothermal revenues accruing to the local governments. Revenues do not cover the immediate fiscal needs resulting from increases in local road maintenance and school enrollment attributable to geothermal development. Several mitigation options are discussed, and a framework is presented for calculating mitigation costs per unit of public service.

Date: May 1, 1982

Creator: Matthews, K.M.

Object Type: Report

System: The UNT Digital Library

(open access)

Pentamethylcyclopentadienyl and bis(trimethylsilyl)amido complexes of the di- and trivalent lanthanides

The reaction of the divalent iodides YbI/sub 2/ and EuI/sub 2/ with NaN(SiMe/sub 3/)/sub 2/ has provided pentane-soluble, monomeric derivatives of the divalent lanthanides. These compounds are isolated as the solvated species Eu(N(SiMe/sub 3/)/sub 2/)/sub 2/L/sub 2/ (L = thf or 1,2-dme), Yb(N(SiMe/sub 3/)/sub 2/)/sub 2/(thf)/sub 1/ /sub 5/ and Yb(N(SiMe/sub 3/)/sub 2/)/sub 2/L/sub 2/ (L = 1,2-dme or OEt/sub 2/), or as the sodium salts NaM(N(SiMe/sub 3/)/sub 2/)/sub 3/ (M = Eu or Yb). The pentamethylcyclopentadienyl ligand has been used to obtain trivalent derivatives of the type (C/sub 5/Me/sub 5/)/sub 2/MCl/sub 2/M'L/sub x/ (M = Nd, Sm or Yb; M' = Li or Na; L = OEt/sub 2/ or tmed) or (C/sub 5/Me/sub 5/)/sub 2/MCl(thf) (M = Nd or Yb). These compounds undergo metathesis reactions. The interaction of NaC/sub 5/Me/sub 5/ with EuCl/sub 3/ yields only the divalent (C/sub 5/Me/sub 5/)/sub 2/EuL (L = thf or OEt/sub 2/). Analogous compounds of ytterbium are obtained by reaction of YbI/sub 2/ with NaC/sub 5/Me/sub 5/ in thf or OEt/sub 2/. The ytterbium amine complexes are weakly paramagnetic, apparently due to charge transfer from ytterbium to the aromatic rings. The divalent phosphine complexes (C/sub 5/Me/sub 5/)/sub 2/ML (M = Eu or Yb; …

Date: March 1, 1982

Creator: Tilley, T. D.

Object Type: Report

System: The UNT Digital Library

(open access)

Analysis of valence-electron structures of Y/sub 3/Al/sub 5/O/sub 12/(YAG) and Al/sub 2/O/sub 3/, Cr/sub 2/O/sub 2/ (Ruby), a study of certain properties of these laser materials related to their valence-electron structures

A direct method of determination of the valence-electron structure from its crystal structure has been presented by the writer at XIIth International Congress of Crystallography, at Ottawa, 1981. Here the method is applied to determine the valence-electron structures of Y/sub 3/Al/sub 5/O/sub 12/ (YAG) and Al/sub 2/O/sub 3/, Cr/sub 2/O/sub 3/ (ruby) to see how certain properties of these laser materials are related to their valence-electron structures. The first point observed is the very strong, continuous, but zig-zag three-dimensional fractional covalent M-O bond nets (M = Al or Cr) being connected with the high melting points, the great resistance against the puncture by the strong laser beam. In the case of Nd-YAG, the distortion caused by the replacement of the Y atoms by almost the same size Nd atoms is small. On the other hand, because of the similarity of the valence-electron structures of ..cap alpha..-Al/sub 2/O/sub 3/ and Cr/sub 2/O/sub 3/, the replacement of Al atoms by the little larger size Cr atoms in small amount is easily understood. The large atomic spins of magnetic moment m/sub B/ = 2.76 ..mu../sub B/ (= experiment value, the theoretical m/sub B/ = 2.70/sub 2/ ..mu../sub B/) of Cr atoms pointing parallel …

Date: January 1, 1982

Creator: Yu, S. H. & Yu, L. H.

Object Type: Article

System: The UNT Digital Library

(open access)

Devil's staircase and order without periodicity in classical condensed matter

The existence of incommensurate structures proves that crystal ordering is not always the most stable one for nonquantum matter. Some properties of structures which are obtained by minimizing a free energy are investigated in the Frenkel Kontorova and related models. It is shown that an incommensurate structure can be either quasi-sinusoidal with a phason mode or built out of a sequence of equidistant defects (discommensurations) which are locked to the lattice by the Peierls force. In that situation the variation of the commensurability ratio with physical parameters forms a complete devil's staircase with interesting physical consequences. Some general results for all structures which minimize a free energy are given. In addition to the known crystal and incommensurate structures, the existence of a new class of structures which have local order at all scale is predicted. Properties of the new class are described in physical terms and possible applications to certain amorphous or nonstoichiometric compounds are discussed.

Date: January 1, 1982

Creator: Aubry, S.

Object Type: Article

System: The UNT Digital Library

(open access)

Useful characteristics of the Savannah River

The following information about the Savannah River is tabulated: significant activities and discharges along the Savannah River, river water temperature data near Jackson st Savannah River Plant, flow informatiom, and reservoir parameters for Clarks Hill, Richard B. Russell and Hartwell reservoirs.

Date: May 19, 1982

Creator: Watts, J. R.

Object Type: Report

System: The UNT Digital Library

(open access)

Role of diagnostic testing in identifying and resolving dimensional-stability problems in electroplated laser mirrors

The metal mirrors which are the subject of this discussion are to be used in the Antares inertial fusion laser system. Antares is a high-power (40 TW), high-energy (35 to 40 kJ), pulsed CO/sub 2/ laser system for the investigation of inertial confinement fusion. The system contains more than four hundred small and large diamond-turned and conventionally polished mirrors. The largest mirrors are trapezoidal in shape with the longest dimension being 16 to 18 inches. The substrates are type 2124 aluminum for most large mirrors, and aluminum bronze, oxygen-free copper or a copper-zirconium alloy for most of the smaller mirrors. The optical surface is electro-deposited copper 20 to 40 mils thick. After nondestructive testing and rough machining, the electroplated surface is single-point diamond machined or conventionally polished.

Date: January 1, 1982

Creator: Cutler, R.L. & Hogan, B.

Object Type: Article

System: The UNT Digital Library

(open access)

Design of a diesel exhaust-gas purification system for inert-gas drilling

To combat the serious oxygen corrosion of drill pipe when a low density drilling fluid (air or mist) is used in geothermal drilling, a system has been designed that produces an inert gas (essentially nitrogen) to be substituted for air. The system fits on three flatbed trailers, is roadable and produces 2000 scfm of gas. The projected cost for gas is slightly less than $2.00 per thousand standard cubic feet.

Date: January 1, 1982

Creator: Caskey, B. C.

Object Type: Article

System: The UNT Digital Library

(open access)

Molecular ingredients of heterogeneous catalysis

The purpose of this paper is to present a review and status report to those in theoretical chemistry of the rapidly developing surface science of heterogeneous catalysis. The art of catalysis is developing into science. This profound change provides one with opportunities not only to understand the molecular ingredients of important catalytic systems but also to develop new and improved catalyst. The participation of theorists to find answers to important questions is sorely needed for the sound development of the field. It is the authors hope that some of the outstanding problems of heterogeneous catalysis that are identified in this paper will be investigated. For this purpose the paper is divided into several sections. The brief Introduction to the methodology and recent results of the surface science of heterogeneous catalysis is followed by a review of the concepts of heterogeneous catalysis. Then, the experimental results that identified the three molecular ingredients of catalysis, structure, carbonaceous deposit and the oxidation state of surface atoms are described. Each section is closed with a summary and a list of problems that require theoretical and experimental scrutiny. Finally attempts to build new catalyst systems and the theoretical and experimental problems that appeared in the …

Date: June 1, 1982

Creator: Somorjai, G.A.

Object Type: Article

System: The UNT Digital Library

(open access)

H5 fast-kicker-magnet pulser

The fast extraction kicker magnet for the AGS is powered by a novel pulse generator. A pulse forming network (PFN) is discharged into nearly 100% mismatched load. The pulser delivers a current pulse of 3000 amperes peak pulse with a 2% flat-top ripple into a 1.4 ..mu.. H single turn ferrite core magnet. The pulse is 2.8 ..mu..sec wide with a 180 nsec rise time, at a 0.5 to 1.5 pps repetition rate. The pulse rise time is required to provide clean extraction of the 28 GeV proton beam by bringing the kicker magnet field up to 1.25 kG within the 220 nsec space between proton bunches in the machine. The pulser is mounted adjacent to the kicker magnet in the AGS ring. The thyratron's characteristics are not affected by the ionizing radiation environment during operation of the AGS (Alternating Gradient Synchrotron).

Date: January 1, 1982

Creator: Frey, W.; Ghoshroy, S. & Cottingham, J.G.

Object Type: Article

System: The UNT Digital Library

(open access)

Floristic composition and plant succession on near-surface radioactive-waste-disposal facilities in the Los Alamos National Laboratory

Since 1946, low-level radioactive waste has been buried in shallow landfills within the confines of the Los Alamos National Laboratory. Five of these sites were studied for plant composition and successional patterns by reconnaissance and vegetation mapping. The data show a slow rate of recovery for all sites, regardless of age, in both the pinon-juniper and ponderosa pine communities. The sites are not comparable in succession or composition because of location and previous land use. The two oldest sites have the highest species diversity and the only mature trees. All sites allowed to revegetate naturally tend to be colonized by the same species that originally surrounded the sites. Sites on historic fields are colonized by the old field flora, whereas those in areas disturbed only by grazing are revegetated by the local native flora.

Date: March 1, 1982

Creator: Tierney, G.D. & Foxx, T.S.

Object Type: Report

System: The UNT Digital Library

(open access)

Effect of reactor coolant pumps following a small break in a pressurized water reactor

Small-break loss-of-coolant accidents were calculated to help determine whether to trip the reactor-coolant pumps early in the accident when the reactor scrams or to delay the pump trip (pump trip times ranged from 450 s to no trip at all). Four-in.-diam (approximate) cold-leg breaks in Babcock and Wilcox (B and W) and Westinghouse (W) pressurized-water reactors were investigated using the Transient Reactor Analysis Code, TRAC-PD2. The results indicated that for a 4-in.-diam cold-leg break the optimum mode of pump operation is design dependent. In terms of primary system mass depletion, the case with no pump trip was preferable for the W plant, whereas an early pump trip was preferable for the B and W plant. When the pumps were not operating in the W plant, the loop seals plugged with liquid, leading to a pressure buildup in the upper plenum and, consequently, a high liquid flow through the break. The vent valves in the B and W plant mitigated the consequences of the loop seals plugging; the effect was enough to favor an early pump trip.

Date: January 1, 1982

Creator: Elliott, J.L.; Lime, J.F. & Willcutt, G.J.E. Jr.

Object Type: Article

System: The UNT Digital Library

(open access)

Low-Btu coal-gasification-process design report for Combustion Engineering/Gulf States Utilities coal-gasification demonstration plant. [Natural gas or No. 2 fuel oil to natural gas or No. 2 fuel oil or low Btu gas]

This report describes a coal gasification demonstration plant that was designed to retrofit an existing steam boiler. The design uses Combustion Engineering's air blown, atmospheric pressure, entrained flow coal gasification process to produce low-Btu gas and steam for Gulf States Utilities Nelson No. 3 boiler which is rated at a nominal 150 MW of electrical power. Following the retrofit, the boiler, originally designed to fire natural gas or No. 2 oil, will be able to achieve full load power output on natural gas, No. 2 oil, or low-Btu gas. The gasifier and the boiler are integrated, in that the steam generated in the gasifier is combined with steam from the boiler to produce full load. The original contract called for a complete process and mechanical design of the gasification plant. However, the contract was curtailed after the process design was completed, but before the mechanical design was started. Based on the well defined process, but limited mechanical design, a preliminary cost estimate for the installation was completed.

Date: June 1, 1982

Creator: Andrus, H E; Rebula, E; Thibeault, P R & Koucky, R W

Object Type: Report

System: The UNT Digital Library

(open access)

Radiochemical analysis of the first plateout probe from the Fort St. Vrain high-temperature gas-cooled reactor

This report presents the analysis of radioactive elements on the first plateout probe from the Fort St. Vrain high-temperature gas-cooled reactor. The plateout probe is a device which samples the primary coolant for condensible fission products. Circuit inventories of individual radionuclides are estimated from the probe analysis. The analysis shows that the radioactive contamination in the primary circuit is remarkable low, with activation product concentrations much greater than that of fission products. The analysis demonstrates that the concentrations of the key fission products I-131 and Sr-90 are far below the limits allowed by the technical specification.

Date: June 1, 1982

Creator: Burnette, R. D.

Object Type: Report

System: The UNT Digital Library

(open access)

Analytical theory of ion-temperature-gradient instability

The relationship between the threshold values of ion-temperature-gradient instabilities and the temperature parameters of plasmas is investigated analytically in slab and toroidal geometries separately. It is found that the threshold values increase rapidly when the ion temperature becomes much higher than the electron temperature. The change of the threshold vaues with respect to the ion temperature is quite similar for both geometric models. This finding is consistent with PLT observations. Furthermore, the analytical results also agree with those of the numerical calculations.

Date: January 19, 1982

Creator: Guo, S.; Shen, J.; Chen, L. & Tsai, S.T.

Object Type: Report

System: The UNT Digital Library

(open access)

Fractional charge search

A device to search for fractional charge in matter is described. The sample is coupled to a low-noise amplifier by a periodically varying capacitor and the resulting signal is synchronously detected. The varying capacitor is constructed as a rapidly spinning wheel. Samples of any material in volumes of up to 0.05 ml may be searched in less than an hour.

Date: June 1, 1982

Creator: Innes, W.; Klein, S.; Perl, M. & Price, J.C.

Object Type: Article

System: The UNT Digital Library

(open access)

Optical-scattering measurements from 1. 06-. mu. m, 0. 53-. mu. m, and 0. 35-. mu. m laser-heated disk targets

A discussion is presented on scattered light measurements relevant to three of the important parametric instabilities which occur in high intensity laser plasma interactions: stimulated Brillouin scattering (SBS), the two plasmon decay instability (2-..omega../sub pe/), and stimulated Raman scattering (SRS). Most of these experiments were carried out on the ARGUS facility. Its configuration is described for the multiple wavelength experiments, all of which were conducted with one beam illumination of flat disk targets.

Date: January 1, 1982

Creator: Turner, R. E.; Campbell, E. M.; Phillion, D. W.; Mead, W. C.; Ze, F.; Max, C. et al.

Object Type: Article

System: The UNT Digital Library

(open access)

Impact of common problems in geothermal drilling and completion

Problems that arise in geothermal drilling and completion account for a significant portion of geothermal well costs. In order to evaluate new technologies for combatting these problems, the relative frequencies and severities of different problems have been estimated. The estimates were based on both subjective judgements and analysis of available drilling records. The most common problems include lost circulation, stuck pipe and cementing, and their impact is to increase well cost by an average of at least 15%.

Date: January 1, 1982

Creator: Carson, C. C. & Lin, Y. T.

Object Type: Article

System: The UNT Digital Library

(open access)

Radiolytic Effects on Ion Exchangers During the Storage of Radioactive Wastes

Radiolytic effects on ion exchangers are being recognized as a significant problem in the processing and storage of high-specific-activity radioactive waste forms. Two major literature surveys and a series of scoping experiments conducted during this investigation indicate that radiation decomposition of ion exchange materials has the potential for a variety of undesirable consequences. These include the ready dispersion of adsorbed radionuclides to the environment, corrosion and pressurization of waste canisters, and generation of flammable and explosive gases, as well as agglomeration of ion exchangers to a rigid monolith with the partitioning of a liquid phase. Some of the highlights of the literature surveys and the major findings of the experimental studies are reported here.

Date: January 1, 1982

Creator: Pillay, K. K. S. & Palau, G. L.

Object Type: Article

System: The UNT Digital Library

FIRST
PREV
1
2
3
4
5
6
7
NEXT
LAST