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Use of Analog Computers for Simulating the Movement of Isotopes in Ecological Systems (open access)

Use of Analog Computers for Simulating the Movement of Isotopes in Ecological Systems

None
Date: January 24, 1962
Creator: Neel, R. B. & Olson, J. S.
System: The UNT Digital Library
Diffusion of Slow Electrons in Gases (open access)

Diffusion of Slow Electrons in Gases

The properties of electrons in a gas and an external electric field, e.g., agitation velocity, free path, energy lost per collision, and collision cross sections, were determined for electrons of energy less than 2 ev in a large number of gases. The computations were made from previously measured values for Townsend's energy factor or the ratio of electron agitation energy to molecule thermal energy. Results are presented for hydrogen, nitrogen, carbon dioxide, methane, ethylene, cyclopropane, and argon. (D.L.C.)
Date: October 24, 1961
Creator: Forester, D. W. & Cochran, L. W.
System: The UNT Digital Library
A Study of the Kinetic and Mechanical Properties of a Stabilized Beta Phase Plutonium Alloy (open access)

A Study of the Kinetic and Mechanical Properties of a Stabilized Beta Phase Plutonium Alloy

The elements Sn, Mg, Ti, Zr, Hf, Si, Cd, and U were alloyed with plutonium to determine their effect on stabilization of the beta phase. Zirconium was found to be the ' most effective. Kinetic studies were conducted on Pu-Zr alloys having 0.24, 0.65, and 1.7 at.% Zr contents. The beta to alpha transformation in the Pu-Zr alloys was somewhat similar to that in unalloyed plutonium. The main difference being that time, temperature, transformation curves of the alloys were shifted to the right as the zirconium concentration increased. It was determined that the amount of beta phase retained at room temperature increased as the zirconium concentration increased. The minimum amount of Zr needed to stabilize the beta phase of plutonium at room temperature was determined to be 2.0 at.%. A 2.4 at.% Zr addition stabilized the beta phase of plutonium at atmospheric pressure from room temperature to 265 deg C. During mechanical property testing it was determined that the stabilized beta Pu-2.4 at.% Zr alloy was brittle from room temperature to 230 deg C. Both tensile and compression strengths of the beta stabilized alloy were greater than the unalloyed beta phase of plutonium. A brittle-ductile transition was noted between 130 …
Date: January 1, 1962
Creator: Taylor, J. M.
System: The UNT Digital Library
RECOMBINATION STATISTICS FOR THE NEUTRON-INDUCED BASE CURRENT COMPONENT. (open access)

RECOMBINATION STATISTICS FOR THE NEUTRON-INDUCED BASE CURRENT COMPONENT.

None
Date: January 1, 1968
Creator: Chow, M.
System: The UNT Digital Library
Theory of ordering transformations in metals and minerals (open access)

Theory of ordering transformations in metals and minerals

This dissertation presents an investigation of ordering in FCC based systems using the pair potential approximation in the ground state and mean field limits. The theoretical approach is used to explain the occurrence of observed equilibrium phases and characteristics of thermodynamic instabilities, in particular, spinodal ordering and decomposition. It is shown that the stability of non-integer domain sizes in long period superstructures such as Al{sub 3}Ti and Ag{sub 3}Mg may result from the tendency of a system to reduce the number of non-dominant ordering waves, thus producing domain sizes that have rational fraction form n/m. This conclusion is used to explain the domain size stability with respect to variations in temperature and electron concentration. The cation ordering in the precipitate phases in calcite and dolomite is analyzed by analogy with ordering in FCC based metals. The ordered phases in calcite and dolomite are shown to be consistent with pair potential minima at {l brace}100{r brace} and {l brace}1/2, 1/2, 1/2{r brace} positions in reciprocal space respectively. 32 refs., 6 figs.
Date: July 1, 1991
Creator: Lindsey, Timothy Francis
System: The UNT Digital Library
INTERACTION OF TWO-DIMENSIONAL, STRATIFIED, TURBULENT AIR--WATER AND STEAM-- WATER FLOWS. (open access)

INTERACTION OF TWO-DIMENSIONAL, STRATIFIED, TURBULENT AIR--WATER AND STEAM-- WATER FLOWS.

None
Date: January 1, 1968
Creator: Linehan, J.H.
System: The UNT Digital Library
Transient Temperature Distributions in a Thermally Orthotropic Plate With Non-Uniform Surface Heating (open access)

Transient Temperature Distributions in a Thermally Orthotropic Plate With Non-Uniform Surface Heating

ent temperature variation in a thermally orthotropic plate which is subjected to an arbitrary heating rate distribution along one face with all other surfaces being insulated. Dimensionless temperature histories and distributions determined from this solution are presented for the special, but representative, case of a linearly varying heating rate distribution on plates with varying degrees of thermal orthotropy. These results establish quantitatively the value of a material with high planar and low normal thermal conductivities for applications where it is desired to maintain minimum temperatures on the rear or unheated surface of a heat shield when the heated surface is subjected to a very non-uniform heating rate distribution. The applicability of simplifying assumptions in analyzing such a system is discussed. Experimental temperature measurements in a pyrolytic graphite plate heated by an oxyacetylene flame were made to verify the analytical results. Achievement of satisfactory agreement wss found to be dependent upon use of thermal property values differing from those presently available for this material. This is not unusual in that differences in production methods are known to introduce substantial property variations in anisotropic materials such as pyrolytic graphite. (auth)
Date: June 1, 1961
Creator: Hornbaker, David Ross
System: The UNT Digital Library
LOW TEMPERATURE COOPERATIVE BEHAVIOR OF THE RARE EARTH SALTS GdCl$sub 3$ AND PrCl . (open access)

LOW TEMPERATURE COOPERATIVE BEHAVIOR OF THE RARE EARTH SALTS GdCl$sub 3$ AND PrCl .

None
Date: January 1, 1971
Creator: Hessler, J.P.
System: The UNT Digital Library
Noise Considerations in Nuclear Pulse Amplifiers (open access)

Noise Considerations in Nuclear Pulse Amplifiers

The effects of certain pulse-shaping networks on the signal-to-noise ratio of a nuclear pulse amplifier were considered. The shaping networks discussed are: equal RC-integrating and RC-differentiating time constant, single- delay-line clipper and RC integrator, and doubledelay-line clipper and RC integrator. The effects of these networks on the signal, when high count rates and overload pulses are present, were also considered. Equations and curves were developed for the energy resolution (signal-tonoise ratio) and resolving time (related to the ability to operate at high counting rates) of the networks. Experimental results are shown for the energy resolution of the types of pulse- shaping networks considered. (auth)
Date: December 20, 1961
Creator: Landis, D. A.
System: The UNT Digital Library
A Theoretical Study of the Transient Operation and Stability of Two-Phase Natural Circulation Loops (open access)

A Theoretical Study of the Transient Operation and Stability of Two-Phase Natural Circulation Loops

Mathematical models of the time-dependent behavior of two-phase natural- circulation loops were used to predict the operation and to explain the unusual instability sometimes observed. The initial results obtained for a loop similar to the Univ. of Minnesota loop were used to formulate a more complex and accurate model, and the predicted transient behavior was in close agreement with the experimental results from the Minnesota loop. For a 300psia, high-pressure loop, unstable oscillatory behavior was predicted under certain conditions and stable behavior under others. Closed unstable regions rather than limits were predicted, and the specifications of stability in terms of a single parameter were found to be impossible. The great difference in oscillatory frequencies observed at low and high pressures was found to be due largely to the system geometry. The criterion for the absence of oscillations was found to be similar to one of the criteria for stability of chemical reaction systems. (D.L.C.)
Date: June 1, 1961
Creator: Garlid, K.; Amundson, N. R. & Isbin, H. S.
System: The UNT Digital Library
Fall and winter movements and activity of muskrats in east-central Minnesota (open access)

Fall and winter movements and activity of muskrats in east-central Minnesota

None
Date: August 1, 1974
Creator: Stolen, Paul Dean
System: The UNT Digital Library
THICKNESS CORRECTIONS FOR NEUTRON-ACTIVATED GOLD FOILS. (open access)

THICKNESS CORRECTIONS FOR NEUTRON-ACTIVATED GOLD FOILS.

None
Date: January 1, 1969
Creator: Stanford, G.S. & Seckinger, J.H.
System: The UNT Digital Library
Formal analysis of name accessing in programming languages. [R] (open access)

Formal analysis of name accessing in programming languages. [R]

None
Date: October 1, 1975
Creator: Smith, C. L.
System: The UNT Digital Library
Low Temperature Thermoluminescence of Gamma Irradiated Potassium Dihydrogen Phosphate (open access)

Low Temperature Thermoluminescence of Gamma Irradiated Potassium Dihydrogen Phosphate

Thermoluminescence in potassium dihydrogen phosphate (KDP) induced by Co/ sup 60/ gamma irradiation at liquid nitrogen temperature (-198 deg C) was investigated. Glow curves in the temperature range --196 to 0 deg C were measured for a series of gamma exposure dosages ranging from 10/sup 4/ roentgen to 5 x 10/sup 6/ roentgen. The heating rate used for glow curve measurements was 12 deg C per minute. Twice recrystallized Mallinckrodt reagent grade potassium dihydrogen phosphate, with a grain size between 100 and 170 mesh, was used for most samples. In the case of the powder samples, the glow curve for an exposure dose of 10/sup 4/ roentgen exhibited two peaks in this temperature range, one at approximately --78 deg C and the other at approximately -146 deg C. The -78 deg C peak split into two distinct peaks with increasing dosage. At still higher doses an additional peak at about -9 deg C became evident. This peak may, however, be due to aluminum oxide. Calculation of the trap depth, E, and the frequency factor, s, associated with the --78 deg C peak, by the approximate method of Grossweiner yielded values of 0.485 ev and 9.97 x 10/sup 10/ sec/sup -1/ …
Date: October 19, 1962
Creator: Sims, T. M.
System: The UNT Digital Library
Americium and plutonium in water, biota, and sediment from the central Oregon coast (open access)

Americium and plutonium in water, biota, and sediment from the central Oregon coast

Plutonium-239, 240 and americium-241 were measured in the mussel Mytilus californianus from the region of Coos Bay, OR. The flesh of this species has a plutonium concentration of about 90 fCi/kg, and an Am-241/Pu-239, 240 ratio that is high relative to mixed fallout, ranging between two and three. Transuranic concentrations in sediment, unfiltered water, and filterable particulates were also measured; none of these materials has an Am/Pu ratio as greatly elevated as the mussels, and there is no apparent difference in the Am/Pu ratio of terrestrial runoff and coastal water. Sediment core profiles do not allow accumulation rates or depositional histories to be identified, but it does not appear that material characterized by a high Am/Pu ratio has ever been introduced to this estuary. Other bivalves (Tresus capax and Macoma nasuta) and a polychaete (Abarenicola sp.) do not have an elevated Am/Pu ratio, although the absolute activity of plutonium in the infaunal bivalves is roughly four times that in the mussels.
Date: June 1, 1982
Creator: Nielsen, R. D.
System: The UNT Digital Library
The Specific Heat of Dysprosium Metal Between 0.4 and 4 K (open access)

The Specific Heat of Dysprosium Metal Between 0.4 and 4 K

Submitted to Illinois Inst. of Tech., Chicago. A He/sup 3/ cryostat was built to measure the specific heat of rare earth metals which have a component, at low temperatures, attributable to the electrons in the incomplete 4f shell. The specific heat of dysprosium from 0.4 to 4.2 deg K was measured. Pertinent theories about specific heats are outlined. The apparatus included the cryostat, vacuum and He/sup 3/ systems, calorimeter, carbon thermometer, heater, and magnetic thermometer. The experimental procedure is described and results are presented in graphic and tabular form. The specific heat rose sharply below 1 deg K. An anomalous hump was centered about 2.35 deg K. (M.C.G.)
Date: August 1, 1962
Creator: Guenther, R. A.
System: The UNT Digital Library
Response of Shortgrass Plains Vegetation to Chronic and Seasonally Administered Gamma Radiation (open access)

Response of Shortgrass Plains Vegetation to Chronic and Seasonally Administered Gamma Radiation

In order to determine the effect of radiation on the structure of native shortgrass plains vegetation, an 8750 Ci 137Cs source was installed on the Central Plains Experimental Range near Nunn, Colorado; The experimental area was divided into 6 treatment sectors, a control, 2 sectors for chronic exposure (irradiation initiated April 1969 and continuing as of August 1971), and one each for spring, summer and late fall seasonal semi-acute (30 day), exposures which were administered during April, July and December, 1969, respectively. Community structure was measured by coefficient of community and diversity index. Yield was determined by clipping plots in September 1970 and visual estimates in September 1969 and 1970 for the grass-sedge component of the vegetation. Individual species sensitivity was determined by density data recorded in April, June and September of 1969 and 1970 and by a phenological index recorded at weekly intervals during the 1969 and 1970 growing seasons. The response of the vegetation was similar whether determined by coefficient of community or diversity with diversity being a more sensitive measure of effects. In the chronically exposed sectors, the exposure rate which resulted in a 50 per cent reduction in these 2 parameters (CC50 or D50) was still …
Date: August 1, 1971
Creator: Fraley, L. Jr.
System: The UNT Digital Library
THE EFFECTIVE ALPHA ACTIVITY OF $sup 238$Pu DIOXIDE MICROSPHERES. (open access)

THE EFFECTIVE ALPHA ACTIVITY OF $sup 238$Pu DIOXIDE MICROSPHERES.

None
Date: January 1, 1969
Creator: Huffman, G.N.
System: The UNT Digital Library
Dynamic Simulation of Multi-Pass Pressurized Water Nuclear Power Plants by Analog Computer Techniques (open access)

Dynamic Simulation of Multi-Pass Pressurized Water Nuclear Power Plants by Analog Computer Techniques

A kinetic model of the primary loop of a multi-pass pressurized water reactor power plant is developed to evaluate, by analog computer techniques, the transient response characteristics under conditions of steam generator load and reactor control rod perturbations. Using the 2-pass 28 Mw(t) SM-2 reactor as a typical plant, transient behavior patterns are illustrated and examined for a variety of load inputs, variations in plant constants, and analog model simplifications. (auth)
Date: June 1, 1961
Creator: Brondel, J. O.
System: The UNT Digital Library
Solid State Neutron Detectors (open access)

Solid State Neutron Detectors

None
Date: May 1, 1961
Creator: Murphy, J. F.
System: The UNT Digital Library
Parametrization of net radiation at the surface using data from the Wangara experiment (open access)

Parametrization of net radiation at the surface using data from the Wangara experiment

Hourly Wangara boundary layer data (Clark et al., 1971) was used to substantiate previously derived empirical equations of the surface radiation budget. These equations only require measurements taken by a surface observer in order to be evaluated. A parameterization was made for infrared (IR) radiation. From this procedure, a residual radiation was obtained from the measured daytime net radiation data in order to approximate short wave (SW) radiation. Diurnal trends in radiation and other related meteorological parameters were also evaluated. For IR radiation, the Brunt equation was found to adequately represent effective radiation without clouds. IR attenuation (K-values) of 0.89, 0.64, and 0.51 were calculated for low, middle, and high clouds, respectively. A modification of Beer's Law was derived to evaluate the residual radiation under clear skies as suggested by Flowers et al. (1969) for SW radiation. With the surface albedo assumed at 0.15, a mean turbidity coefficient of 0.16 was determined. Also, the square root of the optical air mass was found to best represent the data in this equation. An analysis of SW cloud attenuation coefficients (C-values) from the residual radiation proved inconclusive. Of considerable importance is the finding that cloud attenuation of the residual radiation behaved nonlinearly. …
Date: Summer 1980
Creator: Edson, Roger T.
System: The UNT Digital Library