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1995

Utah State University

Series

Articles 1 - 30 of 79

Full-Text Articles in Physical Sciences and Mathematics

Transitions Between Convective Patterns In Chemical Fronts, Y. Wu, D. A. Vasquez, Boyd F. Edwards, J. W. Wilder Dec 1995

Transitions Between Convective Patterns In Chemical Fronts, Y. Wu, D. A. Vasquez, Boyd F. Edwards, J. W. Wilder

All Physics Faculty Publications

We present a theory for the transition from nonaxisymmetric to axisymmetric convection in iodate-arsenous acid reaction fronts propagating in a vertical slab. The transition takes place away from the onset of convection, where a convectionless flat front becomes unstable to a nonaxisymmetric convective front. The transition is studied by numerically solving a reaction-diffusion equation coupled with nonlinear hydrodynamics in a two-dimensional slab.

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Evidence For Crystal-Field Splitting In Surface-Atom Photoemission From Potassium, G. K. Wertheim, D. Mark Riffe Nov 1995

Evidence For Crystal-Field Splitting In Surface-Atom Photoemission From Potassium, G. K. Wertheim, D. Mark Riffe

All Physics Faculty Publications

Photoemission spectra from the shallow 3p3/2 core levels of the surface atoms of metallic potassium exhibit the effects of a small but measurable crystal-field splitting of ∼38 meV. It manifests itself mainly as an apparent angle-dependent modulation of the spin-orbit splitting. This phenomenon may, in general, interfere with accurate determinations of surface-atom core-level shifts.

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Determination Of Horizontal And Vertical Structure Of A Novel Pattern Of Short Period Gravity Waves Imaged During Aloha-93, Michael J. Taylor, D. C. Fritts, J. R. Isler Oct 1995

Determination Of Horizontal And Vertical Structure Of A Novel Pattern Of Short Period Gravity Waves Imaged During Aloha-93, Michael J. Taylor, D. C. Fritts, J. R. Isler

All Physics Faculty Publications

An all‐sky CCD imager has been used to measure the properties of short period gravity waves present over the Hawaiian Islands during the ALOHA‐93 campaign. Observations of emissions from four different altitudes provided a capability to describe the vertical as well as the horizontal structure of the wave field. On several occasions during this campaign an unusual morphology wave pattern was detected that consisted of a group of small‐scale waves oriented in the same direction. These were most noticeable in the OI (557.7 nm) emission, altitude ∼96 km, and were usually observed in association with a larger scale gravity wave. …

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Aloha-93 Measurements Of Intrinsic Agw Characteristics Using The Airborne Airglow Imager And Groundbased Na Wind/Temperature Lidar, G. R. Swenson, Michael J. Taylor, P. Espy, C. S. Gardner, X. Tao Oct 1995

Aloha-93 Measurements Of Intrinsic Agw Characteristics Using The Airborne Airglow Imager And Groundbased Na Wind/Temperature Lidar, G. R. Swenson, Michael J. Taylor, P. Espy, C. S. Gardner, X. Tao

All Physics Faculty Publications

Monochromatic Acoustic Gravity Waves (AGWs) with periods < 1 hour are a prevalent feature in the mesospheric airglow layers. These waves are important dynamically and energetically to the region where their temporal and spatial morphology are not well established. The purpose of this study is establish the intrinsic AGW characteristics over an extended region (as flown by the NCAR Electra aircraft) and to present the data in terms of the predicted spectral domain defined by the Brunt‐Vaisala frequency and the diffusive filtering limit proposed by Gardner [1994]. On October 21, 1993, observations were made from the NCAR Electra aircraft during a 6 hour flight in a large triangle N and W of Maui, for a integral distance of ∼3000 km. The entire area observed [∼1 M km²] had a monochromatic AGW propagating toward the NW and the western half had a SW propagating wave superimposed. These waves were also observed with the Michelson interferometer on the aircraft and an airglow imager at the Haleakala location during this time. Intrinsic phase velocities were computed where the Na Wind/Temperature (W/T) lidar at Haleakala provided a measure of the mean wind to compensate phase velocities observed with the imager. The data were tabulated and plotted in an AGW spectral reference frame and compared to cutoff conditions predicted by diffusive filtering theory.

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Maximum Penetration Of Atmospheric Gravity Waves Observed During Aloha-93, G. R. Swenson, C. S. Gardner, Michael J. Taylor Oct 1995

Maximum Penetration Of Atmospheric Gravity Waves Observed During Aloha-93, G. R. Swenson, C. S. Gardner, Michael J. Taylor

All Physics Faculty Publications

Atmospheric Gravity Waves (AGWs) are subject to altitude propagation limits which are governed by the diffusion processes. Diffusion times and scales which exceed the wave period and wavelength define the limiting domain for AGWs. An expression is presented which defines the upper altitude limit to which AGWs can propagate given vertical diffusion constraints of the atmosphere. Airglow, lidar, and radar measurements are combined to characterize the intrinsic AGW parameters in the 80–105 km altitude region. A subset of AGWs (17) observed by airglow imagers during the ALOHA‐93 were made when simultaneous wind measurements were available and intrinsic wave parameters were …

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Spectrometric And Imaging Measurements Of A Spectacular Gravity Wave Event Observed During The Aloha-93 Campaign, Michael J. Taylor, D. N. Turnbull, R. P. Lowe Oct 1995

Spectrometric And Imaging Measurements Of A Spectacular Gravity Wave Event Observed During The Aloha-93 Campaign, Michael J. Taylor, D. N. Turnbull, R. P. Lowe

All Physics Faculty Publications

During the ALOHA‐93 campaign coincident imaging and interferometric measurements of the near infrared and visible wavelength nightglow emissions were made from Haleakala Crater, Maui. On 10 October, 1993 a most unusual wave event was observed. This disturbance appeared as a sharp “front” followed by several conspicuous wave crests which progressed rapidly through the imager's field of view (180°). As the front passed overhead the interferometer detected a sudden jump in both the OH intensity (>50%) and its rotational temperature (∼20 K) with the temperature increase leading the intensity by almost 15 min. At the same time the imager registered …

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An Investigation Of Intrinsic Gravity Wave Signatures Using Coordinated Lidar And Nightglow Image Measurements, Michael J. Taylor, Y. Y. Gu, X. Tao, C. S. Gardner, M. B. Bishop Oct 1995

An Investigation Of Intrinsic Gravity Wave Signatures Using Coordinated Lidar And Nightglow Image Measurements, Michael J. Taylor, Y. Y. Gu, X. Tao, C. S. Gardner, M. B. Bishop

All Physics Faculty Publications

Simultaneous observations of gravity waves using an Na wind/temperature lidar and a multi‐wavelength all‐sky nightglow imager were obtained, for the first time, during the ALOHA‐93 campaign. A novel investigation of intrinsic wave parameters has been made by combining measurements of the horizontal wave components imaged in four nightglow emissions (height range ∼80–100 km) with Na lidar soundings of the horizontal wind field and temperature profiles over the same height interval. On October 19 both instruments registered marked monochromatic wave motions. The intrinsic periods of several of these waves have been determined and were found to vary considerably with altitude, often …

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Height Measurements Of Oi (557.7 Nm) Gravity Wave Structure Over The Hawaiian Islands During Aloha-93, Michael J. Taylor, G. R. Swenson, V. Taylor Oct 1995

Height Measurements Of Oi (557.7 Nm) Gravity Wave Structure Over The Hawaiian Islands During Aloha-93, Michael J. Taylor, G. R. Swenson, V. Taylor

All Physics Faculty Publications

During the ALOHA‐93 campaign simultaneous observations of gravity wave structure in the OI(557.7 nm) nightglow emission were made using two all‐sky CCD imagers; one located near the summit of Haleakala Crater, Maui and the other at Mauna Loa Observatory, Hawaii. On 19 October a set of bright, planar, monochromatic waves was imaged by both systems as it progressed rapidly over the Hawaiian Islands. Triangulation on these wave forms indicates a mean altitude of 95±2 km in good agreement with previous rocket soundings at mid‐latitudes. Two methods of triangulation were employed, both achieving similar results.

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All-Sky Measurements Of Short Period Waves Imaged In The Oi (557.7 Nm), Na(589.2 Nm) And Near Infrared Oh And O2(0,1) Nightglow Emissions During The Aloha-93 Campaign, Michael J. Taylor, M. B. Bishop, V. Taylor Oct 1995

All-Sky Measurements Of Short Period Waves Imaged In The Oi (557.7 Nm), Na(589.2 Nm) And Near Infrared Oh And O2(0,1) Nightglow Emissions During The Aloha-93 Campaign, Michael J. Taylor, M. B. Bishop, V. Taylor

All Physics Faculty Publications

As part of the ALOHA‐93 campaign a high performance all‐sky CCD imaging system was operated at Haleakala Crater, Maui, to obtain novel information on the properties and sources of short period gravity waves over an extended height range ∼80–100 km. Sequential observations of the near infrared OH and O2(0,1) bands and the visible wavelength OI(557.7 nm) and Na(589.2 nm) line emissions have enabled a unique comparison of the morphology and dynamics of the wave motions and their occurrence frequency at each emission altitude to be made. Two major findings are: (a) the detection of significantly higher amounts of wave structure …

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A Two-Dimensional Spectral Analysis Of Short Period Gravity Waves Imaged In The Oi (557.7 Nm) And Near Infrared Oh Nightglow Emissions Over Arecibo, Puerto Rico, Michael J. Taylor, F. J. Garcia Sep 1995

A Two-Dimensional Spectral Analysis Of Short Period Gravity Waves Imaged In The Oi (557.7 Nm) And Near Infrared Oh Nightglow Emissions Over Arecibo, Puerto Rico, Michael J. Taylor, F. J. Garcia

All Physics Faculty Publications

In January 1993 an extensive set of radar and optical data was gathered from various key sites around the world during a coordinated “10 Day Run” designed to investigate the coupled dynamic behavior of the upper atmosphere on a large, medium and small scale. As part of this campaign an all‐sky CCD imaging system was operated at Arecibo Observatory, Puerto Rico, to help quantify the response of the low latitude mesosphere‐thermosphere system to short period (<1 hour) gravity waves. Measurements of the OI(557.7 nm) and near infrared OH nightglow emissions were made in conjunction with photometric and ISR radar soundings and revealed an abundance of small‐scale structure in the 80–100 km range. In this letter we apply two‐dimensional spectral analysis techniques to aid in the interpretation of a complex set of image data that consisted of two intersecting quasi‐monochromatic gravity wave patterns progressing on approximately orthogonal headings. An investigation of the spectral content and temporal evolution of these wave motions at each emission altitude is presented.

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Simultaneous Determination Of Fe 3p Spin-Orbit And Exchange Splittings In Photoemission, D. J. Huang, D. Mark Riffe, J. L. Erskine Jun 1995

Simultaneous Determination Of Fe 3p Spin-Orbit And Exchange Splittings In Photoemission, D. J. Huang, D. Mark Riffe, J. L. Erskine

All Physics Faculty Publications

Spin-resolved core-level photoemission data from the 3p level of ultrathin Fe films [1.4–5.1 monolayers (ML)] epitaxially grown on W(110) have been obtained. A nonlinear least-squares analysis, based on a one-particle Hamiltonian that simultaneously includes core-valence exchange and core-hole spin-orbit interactions, is developed. It is first tested on Fe 2p magnetic circular dichroism (MCD) photoemission spectra and shown to successfully describe the MCD asymmetry data. The model is then used to analyze our thin-film 3p data. With increasing film thickness the spin-orbit splitting (0.67±0.02 eV) remains constant (as expected), the exchange splitting increases from 0±0.12 eV to 0.41±0.05 eV, the average …

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Brine Shrimp Ecology In The Great Salt Lake, Utah, Wayne A. Wurtsbaugh Jun 1995

Brine Shrimp Ecology In The Great Salt Lake, Utah, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Hypersaline lakes are noted for their simple communities which facilitate understanding ecological interactions (Williams et al. 1990; Wurtsbaugh 1992; Jellison and Melack 1988). Nevertheless, we still cannot easily predict how environmental changes will effect the population dynamics in these lakes, at least in part because even these simple ecosystems may be more complex than we .realize. Many hypersaline lakes are dominated by the brine shrimp Artemia spp. The production of brine shrimp is often very high because the terminal, saline lakes accumulate nutrients that make them rich, and because the short food chains in them (nutrients-->phytoplankton-->brine shrimp) minim …

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Finite Thermal Diffusivity At Onset Of Convection In Autocatalytic Systems: Discontinuous Fluid Density, D. A. Vasquez, Boyd F. Edwards, J. W. Wilder Jun 1995

Finite Thermal Diffusivity At Onset Of Convection In Autocatalytic Systems: Discontinuous Fluid Density, D. A. Vasquez, Boyd F. Edwards, J. W. Wilder

All Physics Faculty Publications

A linear convective stability analysis for propagating autocatalytic reaction fronts includes density differences due to both thermal and chemical gradients. Critical parameters for the onset of convection are calculated for an unbounded geometry, a vertical slab, and a vertical cylinder. Thermal effects are important at unstable wavelengths well above the critical wavelength for the onset of convection.

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Effects Of Flaming Gorge Dam Hydropower Operations On Flow And Stage In The Green River, Utah And Colorado, S.C.L Yin, United States Department Of Energy, Environmental Assessment Division, Argonne National Laboratory, J.J. Mccoy, S.C. Palmer May 1995

Effects Of Flaming Gorge Dam Hydropower Operations On Flow And Stage In The Green River, Utah And Colorado, S.C.L Yin, United States Department Of Energy, Environmental Assessment Division, Argonne National Laboratory, J.J. Mccoy, S.C. Palmer

All U.S. Government Documents (Utah Regional Depository)

No abstract provided.

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Conduction-Electron Screening In The Bulk And At Low-Index Surfaces Of Ta Metal, D. Mark Riffe, W. Hale, B. Kim, J. L. Erskine Apr 1995

Conduction-Electron Screening In The Bulk And At Low-Index Surfaces Of Ta Metal, D. Mark Riffe, W. Hale, B. Kim, J. L. Erskine

All Physics Faculty Publications

High-resolution core-level photoemission spectra from Ta(100) have been measured. The well-resolved peak from the first atomic layer allows a separate assessment of bulk and surface-layer screening responses: singularity indices αB=0.10±0.01 and α100=0.205±0.025, respectively, are obtained. The measured surface-atom lifetime broadening of 70±20 meV (compared to 37±5 meV in the bulk) is consistent with published Auger–photoemission coincidence measurements. The result for the bulk singularity index has been applied in the analysis of previous data in order to extract the screening response in the first atomic layer of Ta(111) (α111=0.16±0.01) and Ta(110) (α110=0.150±0.015). The …

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Federal Commodity Programs And Returns To Irrigation In The West, Marcel P. Aillery, Economic Research Service, Natural Resources And Environment Division Mar 1995

Federal Commodity Programs And Returns To Irrigation In The West, Marcel P. Aillery, Economic Research Service, Natural Resources And Environment Division

All U.S. Government Documents (Utah Regional Depository)

This report examines the impact of Federal commodity programs on returns to irrigation in the western United States. Returns to irrigation are defined as average returns to land, management, fixed capital, and water (above variable water cost), net of returns to dryland crop alternatives. Commodity market returns and program revenues per unit of applied irrigation water are estimated by field crop and subregion. Two representative study years - 1984 and 1987 - highlight the effect of differing commodity prices and program support levels under extreme market conditions. Aggregate returns to irrigation in western field-crop production were fairly constant over the …

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Proceedings Of The 1995 Annual Symposium On Engineering Geology And Geotechnical Engineering (No. 31), Joseph A. Caliendo Mar 1995

Proceedings Of The 1995 Annual Symposium On Engineering Geology And Geotechnical Engineering (No. 31), Joseph A. Caliendo

Reports

No abstract provided.

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Mass Distribution On Clusters At The Percolation Threshold, M. F. Gyure, M. V. Ferer, Boyd F. Edwards, G. Huber Mar 1995

Mass Distribution On Clusters At The Percolation Threshold, M. F. Gyure, M. V. Ferer, Boyd F. Edwards, G. Huber

All Physics Faculty Publications

Monte Carlo simulations and a scaling hypothesis are used to study the distribution of blob masses on two-dimensional finite-mass clusters at the percolation threshold. The exponents associated with this distribution function are a combination of backbone and percolation exponents. This work offers insights into the structure and fragmentation properties of percolation clusters in particular, and provides methods applicable to other fractal distribution problems in general.

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Passageway Around The Redlands Diversion Dam And Interim Agreement To Provide Water For Endangered Fish, Bureau Of Reclamation, Fish And Wildlife Service, U.S. Department Of The Interior Feb 1995

Passageway Around The Redlands Diversion Dam And Interim Agreement To Provide Water For Endangered Fish, Bureau Of Reclamation, Fish And Wildlife Service, U.S. Department Of The Interior

All U.S. Government Documents (Utah Regional Depository)

This draft environmental assessment (EA) discusses two related actions proposed to assist in the recovery of two Federally-listed endangered fish species. The actions are intended to restore use of historic and designated critical habitat of the Gunnison River by the Colorado squawfish and razorback sucker. The proposed actions are to: construct and operate a fish passageway around the Redlands Diversion Dam; and execute an interim (short-term) memorandum of agreement (water agreement) to supply streamflows needed to operate the passageway and maintain downstream fish habitat and access for fish to the passageway. The EA is prepared jointly by the Bureau of …

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Fuel System Maintenance, Von Jarrett Feb 1995

Fuel System Maintenance, Von Jarrett

All Current Publications

No abstract provided.

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Caring For Your Tires, Von Jarrett Feb 1995

Caring For Your Tires, Von Jarrett

All Current Publications

No abstract provided.

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What You Need To Know About Retreads, Von Jarrett Feb 1995

What You Need To Know About Retreads, Von Jarrett

All Current Publications

No abstract provided.

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Convective Chemical-Wave Propagation In The Belousov- Zhabotinsky Reaction, Y. Wu, D. A. Vasquez, Boyd F. Edwards, J. W. Wilder Feb 1995

Convective Chemical-Wave Propagation In The Belousov- Zhabotinsky Reaction, Y. Wu, D. A. Vasquez, Boyd F. Edwards, J. W. Wilder

All Physics Faculty Publications

We investigate the onset of convection for chemical-wave propagation in the Belousov-Zhabotinsky reaction based on the two-variable Oregonator model coupled with the fluid dynamic equations. For chemical waves in a vertical slab, two-dimensional convection occurs only for slab widths greater than a critical threshold width. The convective threshold is different for ascending and descending waves. Convectionless waves are flat and propagate with constant speed. Above the onset of convection, the wave velocity increases and the flat wave deforms due to two counterrotating steady rolls. For a horizontal slab, convection is always present and the wave velocity increases with increasing slab …

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Bleeding Air From Diesel Fuel Lines & Filters, Von Jarrett Feb 1995

Bleeding Air From Diesel Fuel Lines & Filters, Von Jarrett

All Current Publications

No abstract provided.

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Machinery Storage, Von Jarrett Feb 1995

Machinery Storage, Von Jarrett

All Current Publications

No abstract provided.

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Cold Tractor Operations, Von Jarrett Feb 1995

Cold Tractor Operations, Von Jarrett

All Current Publications

No abstract provided.

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Drain That Antifreeze, Von Jarrett Feb 1995

Drain That Antifreeze, Von Jarrett

All Current Publications

No abstract provided.

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Is There Slime In Your Fuel, Von Jarrett Feb 1995

Is There Slime In Your Fuel, Von Jarrett

All Current Publications

No abstract provided.

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Diesel Engines, Von Jarrett Feb 1995

Diesel Engines, Von Jarrett

All Current Publications

No abstract provided.

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Preventive Maintenance Checklist, Von Jarrett Feb 1995

Preventive Maintenance Checklist, Von Jarrett

All Current Publications

No abstract provided.

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