Theses (Unassigned)
http://hdl.handle.net/11122/5175
2024-03-21T14:02:38ZPorphyry copper, copper skarn, and volcanogenic massive sulfide occurrences in the Chandalar copper district, Alaska
http://hdl.handle.net/11122/11957
Porphyry copper, copper skarn, and volcanogenic massive sulfide occurrences in the Chandalar copper district, Alaska
Nicholson, Lisa
Metamorphosed porphyry copper, copper skarn, and volcanogenic massive sulfide (VMS) occurrences have been found in 5 key prospects within Devonian rocks of the Chandalar copper district, Alaska. The Venus, Victor, Eva, and Evelyn Lee prospects contain "proximal" porphyry copper/copper skarn mineralization, whereas the Luna prospect contains "distal" Cu-Zn skarn and Cu-Zn VMS mineralization. Porphyry copper mineralization is recognized by granodiorite composition meta-intrusives; zoned potassic, sericitic and propylitic alteration; and del34S values of -1.5 to -0.6 per mil. Skarns consist of
andraditic garnet (Ad30-100) and diopsidic pyroxene (Hd9-46), and have del34S values of -4.7 to -1.1 per mil. Alteration types in intrusive rocks and adjacent skarn are generally compatible. VMS occurrences contain chloritic and silicic alteration, and massive sulfides have del34S values of -0.8 to 6.9 per mil, consistent with values from known Devonian VMS deposits.
Thesis (M.S.) University of Alaska Fairbanks, 1990
1990-05-01T00:00:00ZThe kinetics of glucose limited growth by a marine yeast
http://hdl.handle.net/11122/10560
The kinetics of glucose limited growth by a marine yeast
McNab, Allen David
The kinetics of glucose limited growth by a marine
yeast, shown to be a Rhodotorula species, have been
studied in a continuous culture apparatus. The saturation
constant, in synthetic media, has been calculated to be
0.25 mg/l, on the assumption that saturation kinetics are
followed, The maximum growth rate was determined in both
synthetic media, and artificial sea water. On the basis
of inhibition kinetics, the kinetic behavior of this
yeast in the marine environment has been predicted.
The effect of temperature on the maximum growth
rate has been determined and, on the assumption of a
similar effect on the saturation constant, the saturation
constant has been postulated to be in agreement with
similar values determined for other microorganisms.
Thesis (M.S.) University of Alaska Fairbanks, 1969
1969-05-01T00:00:00ZSmall spatial and fast temporal ionosphere -magnetosphere coupling processes
http://hdl.handle.net/11122/9557
Small spatial and fast temporal ionosphere -magnetosphere coupling processes
Zhu, Hua
I have developed a two-dimensional, three-fluid model (electrons, ions and neutrals) to simulate small-scale magnetosphere-ionosphere coupling processes. The code includes ionization and recombination processes, the Hall term in Ohm's law, and various heat sources in the energy equations. The electro-dynamic response and the evolution of the collision frequencies are treated self-consistently in a height resolved ionosphere. The model allows for the propagation of Alfven waves. The simulation is particularly suited for fast temporal variations and small spatial scale ionospheric structures associated with filamentary aurora and ionospheric heating experiments (e.g. HAARP). I have investigated the evolution of field-aligned currents in the magnetosphere-ionosphere system and found several notable effects---ion heating due to plasma-neutral friction, electron heating resulting from energetic particle precipitation and ohmic dissipation by strong field-aligned currents. The simulation of plasma. heating in the ionosphere is motivated by a specific auroral event that was simultaneously observed with optical and radar instruments. The results indicate that a consistent explanation of this event requires ohmic heating of electrons in a strong field-aligned electric current layer. They suggest strongly that the observed sequence of events can be explained only if spatial structure is present in the ionosphere so that it requires at least a two-dimensional model. Electron heating in strong field-aligned currents also provides a mechanism to deposit energy in the F-region of ionosphere and thus can explain the formation of tall auroral arcs. The simulation of the formation of field-aligned currents shows a strong plasma density depletion in the region of downward field-aligned current layer. The depletion is due to the divergent flow of the plasma. Similarly, the plasma density increases in the region of upward field-aligned current because of the convergent plasma motion. A modification of the ionospheric conditions by localized particle precipitation has an interesting effect. At the edge of the precipitation region, a new field-aligned current filament is formed. Finally, the simulation code is not limited by steady state assumptions commonly used for the Hall model and Pedersen conductivities.
Dissertation (Ph.D.) University of Alaska Fairbanks, 2000
2000-01-01T00:00:00ZModeling of Arctic stratus cloud formation and the maintenance of the cloudy Arctic boundary layer
http://hdl.handle.net/11122/9556
Modeling of Arctic stratus cloud formation and the maintenance of the cloudy Arctic boundary layer
Zhang, Qiuqing
The formation of Arctic stratus clouds (ASCs) and the maintenance of the cloudy Arctic boundary layer are studied with two models: a one-dimensional radiative-convective model and a three-dimensional large eddy simulation (LES) model. The one-dimensional radiative-convective model consists of a comprehensive radiative module, a cloud parameterization with detailed microphysics and a convective adjustment scheme. The model is designed specifically for studying ASC formation. With this model, the roles of radiation and cloud microphysics in the formation of ASCs and multiple cloud layers are investigated. The simulations reproduce both single and multiple cloud layers that were observed with inversions of temperature and humidity occurring near the cloud top. The detailed cloud microstructure produced by the model also compares well with the observations. The physics of the formation of both single and multiple cloud layers is investigated. Radiative cooling plays a key role during the initial stage of cloud formation in a atmosphere. It leads to a continual temperature decrease promoting water vapor condensation on available cloud condensation nuclei. The vertical distribution of humidity and temperature determines the radiative cooling and eventually where and when the cloud forms. The observed temperature inversion may also be explained by radiative cooling. The three-dimensional LES model is adopted to evaluate the one-dimensional model, especially the convective adjustment scheme. The advantages and limitations of the one-dimensional model are discussed. The LES results suggest that the convective adjustment scheme is capable of capturing the main features of the vertical heat and moisture fluxes in the cloudy Arctic boundary layer. The LES model is also used to investigate the maintenance of the cloudy Arctic boundary layer. The turbulence in the cloudy Arctic boundary layer is primarily maintained by the buoyancy effect due to the cloud top cooling. It is found that weak large scale downward motion aids in cloud development and maintenance.
Dissertation (Ph.D.) University of Alaska Fairbanks, 1999
1999-01-01T00:00:00Z