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Fuel Saving Strategies For Separated Spacecraft Interferometry, Timothy Mclain, Randal W. Beard, Christopher A. Bailey Aug 2000

Fuel Saving Strategies For Separated Spacecraft Interferometry, Timothy Mclain, Randal W. Beard, Christopher A. Bailey

Faculty Publications

Separated spacecraft interferometry missions will require spacecraft to move in a coordinated fashion to ensure minimal and balanced consumption of fuel. This paper develops strategies for determining interferometry mission plans that result in significant fuel savings over standard approaches. Simulation results demonstrate that valuable reductions in fuel consumption can be realized by combining the retargeting and imaging maneuvers required to image multiple stellar sources. Fuel-optimal imaging strategies have been developed for two-spacecraft interferometry missions similar to the proposed Space Technology 3 mission using chained local optimization methods. Based on these strategies, sampling pattern guidelines for space-borne interferometry missions have been …

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An Iterative Approach To Multisensor Sea Ice Classification, David G. Long, Mark R. Drinkwater, Quinn P. Remund Jul 2000

An Iterative Approach To Multisensor Sea Ice Classification, David G. Long, Mark R. Drinkwater, Quinn P. Remund

Faculty Publications

Characterizing the variability in sea ice in the polar regions is fundamental to an understanding of global climate and the geophysical processes governing climate changes. Sea ice can be grouped into a number of general classes with different characteristics. Multisensor data from NSCAT, ERS-2, and SSM/I are reconstructed into enhanced resolution imagery for use in ice-type classification. The resulting twelve-dimensional data set is linearly transformed through principal component analysis to reduce data dimensionality and noise levels. An iterative statistical data segmentation algorithm is developed using maximum likelihood (ML) and maximum a posteriori (MAP) techniques. For a given ice type, the …

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Azimuth Variation In Microwave Scatterometer And Radiometer Data Over Antarctica, David G. Long, Mark R. Drinkwater Jul 2000

Azimuth Variation In Microwave Scatterometer And Radiometer Data Over Antarctica, David G. Long, Mark R. Drinkwater

Faculty Publications

While designed for ocean observation, scatterometer and radiometer data have proven very useful in a variety of cryosphere studies. Over large regions of Antarctica, ice sheet and bedrock topography and the snow deposition, drift, and erosional environment combine to produce roughness on various scales. Roughness ranges from broad, basin-scale ice-sheet topography at 100 km wavelengths to large, spatially coherent dune fields at 10 km wavelength to erosional features on the meter scale known as sastrugi. These roughness scales influence the microwave backscattering and emission properties of the surface, combining to introduce azimuth-angle dependencies in the satellite observation data. In this …

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Diversity Performance Of Dual-Antenna Handsets Near Operator Tissue, Michael A. Jensen, Bruce M. Green Jul 2000

Diversity Performance Of Dual-Antenna Handsets Near Operator Tissue, Michael A. Jensen, Bruce M. Green

Faculty Publications

This paper presents a computational and experimental study of the diversity performance of two dual-antenna handsets operating indoors in the 902-928 MHz industrial, scientific, and medical (ISM) band. Of particular interest is the effect of the operator tissue on the diversity operation. Key indicators of diversity gain such as branch mean effective gain (MEG) and envelope correlation coefficient are obtained from finite-difference time-domain (FDTD) method simulations as well as from experimental measurements in three different indoor environments. Diversity gain for the handsets is also measured directly. Reasonable agreement is observed between the experimental and simulated results, with both approaches indicating …

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Neural Networks Versus Nonparametric Neighbor-Based Classifiers For Semisupervised Classification Of Landsat Thematic Mapper Imagery, Perry J. Hardin Jul 2000

Neural Networks Versus Nonparametric Neighbor-Based Classifiers For Semisupervised Classification Of Landsat Thematic Mapper Imagery, Perry J. Hardin

Faculty Publications

Semisupervised classification is one approach to converting multiband optical and infrared imagery into landcover maps. First, a sample of image pixels is extracted and clustered into several classes. The analyst next combines the clusters by hand to create a smaller set of groups that correspond to a useful landcover classification. The remaining image pixels are then assigned to one of the aggregated cluster groups by use of a per-pixel classifier. Since the cluster aggregation process frequently creates groups with multivariate shapes ill suited for parametric classifiers, there has been renewed interest in nonparametric methods for the task. This research reports …

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The World At Its Gravest And Best, Nancy Hanks Baird Jul 2000

The World At Its Gravest And Best, Nancy Hanks Baird

BYU Studies

No abstract provided.

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Electronic Structure Of Bas And Boride Iii-V Alloys, Gus L. W. Hart, Alex Zunger Jun 2000

Electronic Structure Of Bas And Boride Iii-V Alloys, Gus L. W. Hart, Alex Zunger

Faculty Publications

Boron arsenide, the typically ignored member of the Group-III–V arsenide series BAs-AlAs-GaAs-InAs is found to resemble silicon electronically: its Γ conduction-band minimum is p-like (Γ15), not s-like (Γ1c), it has an X1c-like indirect band gap, and its bond charge is distributed almost equally on the two atoms in the unit cell, exhibiting nearly perfect covalency. The reasons for these are tracked down to the anomalously low atomic p orbital energy in the boron and to the unusually strong s–s repulsion in BAs relative to most other Group-III–V compounds. We find unexpected valence-band offsets of BAs with respect to GaAs and …

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Fast Algorithm For Generating Sorted Contour Strings, Norman L. Jones, Michael J. Kennard, Alan K. Zundel Jun 2000

Fast Algorithm For Generating Sorted Contour Strings, Norman L. Jones, Michael J. Kennard, Alan K. Zundel

Faculty Publications

Automatic generation of contours for graphical display and map plotting has been studied extensively since the early days of computing. The individual segments making up a contour line are often determined by subdividing the object of interest into small triangles and computing the contours assuming a linear variation on each triangle. However, efficient storage of contour data and the need to place labels (automatically) or to smooth the contours require that the contours be generated in continuous strings of segments. A simple approach to generate such strings is to sort the randomly generated contour segments. Since sorting can be time-consuming, …

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Comparison Of Charged Sheets And Corrected 3-D Ewald Calculations Of Long-Range Forces In Slab Geometry Electrolyte Systems With Solvent Molecules, Richard L. Rowley, Paul S. Crozier, Eckhard Spoht, Douglas Henderson Jun 2000

Comparison Of Charged Sheets And Corrected 3-D Ewald Calculations Of Long-Range Forces In Slab Geometry Electrolyte Systems With Solvent Molecules, Richard L. Rowley, Paul S. Crozier, Eckhard Spoht, Douglas Henderson

Faculty Publications

Two methods of calculating long-range intermolecular potentials are compared for an approximately 3 M aqueous electrolyte solution confined between two charged surfaces. We investigate the ionic density profiles using the charged-sheets method and the corrected three-dimensional (3D) Ewald method at two different system sizes and also compare the Coulomb forces directly. The corrected 3D Ewald method is recommended for the calculation of long-range potentials in systems of this nature because it is less system size dependent than the charged sheets method and the resultant forces are more consistent with periodic boundaries. However, the charged-sheets method for estimating long-range potentials in …

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Statistical Continuum Theory For Large Plastic Deformation Of Polycrystalline Materials, Brent L. Adams, S. Ahzi, H. Garmestani, S. Lin Jun 2000

Statistical Continuum Theory For Large Plastic Deformation Of Polycrystalline Materials, Brent L. Adams, S. Ahzi, H. Garmestani, S. Lin

Faculty Publications

This paper focuses on the application of statistical continuum mechanics to the prediction of mechanical response of polycrystalline materials and microstructure evolution under large plastic deformations. A statistical continuum mechanics formulation is developed by applying a Green's function solution to the equations of stress equilibrium in an infinite domain. The distribution and morphology of grains (crystals) in polycrystalline materials is represented by a set of correlation functions that are described by the corresponding probability functions. The elastic deformation is neglected and a viscoplastic power law is employed for crystallographic slip in single crystals. In this formulation, two- and three-point probability …

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Committee Activities, Doris Seely, Frank L. Chance, Sarah S. Elman Jun 2000

Committee Activities, Doris Seely, Frank L. Chance, Sarah S. Elman

Journal of East Asian Libraries

No abstract provided.

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Book Review: Schattenkrieg Gegen Hitler: Das Dritte Reich Im Visier Der Amerikanischen Geheimdienste, Christof Muenger Jun 2000

Book Review: Schattenkrieg Gegen Hitler: Das Dritte Reich Im Visier Der Amerikanischen Geheimdienste, Christof Muenger

Swiss American Historical Society Review

In the 1980' s the United States government decided to declassify the files of the Office of Strategic Services (OSS) which was the organization preceding the CIA. Christoph Mauch, a German historian and Deputy Director of the German Historical Institute in Washington, DC, thoroughly studied the numerous now available documents. His research in the National Archives as well as in various other archives in the United States and Europe resulted in his Habilitationsschrift [a scholar's second study after the doctoral dissertation to make one eligible for a university position in Germany]. A shortened and revised version of the study has …

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A Gis Model To Predict The Location Of Fossil Packrat (Neotoma) Middens In Central Nevada, Scott A. Mensing, Robert G. Elston Jr., Gary L. Raines, Robin J. Tausch, Cheryl L. Nowak May 2000

A Gis Model To Predict The Location Of Fossil Packrat (Neotoma) Middens In Central Nevada, Scott A. Mensing, Robert G. Elston Jr., Gary L. Raines, Robin J. Tausch, Cheryl L. Nowak

Western North American Naturalist

Fossil packrat (Neotoma) middens provide an important source of paleoecologic data in the arid West. This study describes and tests a predictive GIS model that uses the eights-of-evidence method for determining areas with a high probability of containing fossil middens in central Nevada. Model variables included geology, elevation, and aspect. Geology was found to be the most important variable tested. We produced a map of 4 probability classes validated by field-checking 21 randomly selected 1-km2 sites throughout the study area. Our high-probability category reduced the search area to only 3.5% of the total study area. Fossil middens …

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Full Issue, Vol. 60 No. 2 May 2000

Full Issue, Vol. 60 No. 2

Western North American Naturalist

No abstract provided.

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Globalization And The Need For International Language Standards, Alan K. Melby Apr 2000

Globalization And The Need For International Language Standards, Alan K. Melby

Deseret Language and Linguistic Society Symposium

No abstract provided.

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Macroeconomic Stabilization And The Microentrepreneur, Jeffrey R. Franks Apr 2000

Macroeconomic Stabilization And The Microentrepreneur, Jeffrey R. Franks

Journal of Microfinance / ESR Review

Macroeconomic instability is largely detrimental to microenterprises. An unstable economic environment generates inflation and thus hits small business and the poor more severely than the more formal, wealthier segments of the population. Stabilization policies, which eliminate these disadvantages of instability, can help microenterprise. While healthy macroeconomic factors can positively influence the informal economy, the so-called “informal sector” can strengthen the macroeconomy. Given proper underlying conditions, microenterprise may prove as an engine of growth for an entire economy, and not just a small subsector of only marginal macroeconomic importance. This article discusses the effects of these macro-micro links with a special …

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Fuel Optimization For Constrained Rotation Of Satellite Formations, Timothy Mclain, Randal W. Beard, Fred Y. Hadaegh Apr 2000

Fuel Optimization For Constrained Rotation Of Satellite Formations, Timothy Mclain, Randal W. Beard, Fred Y. Hadaegh

Faculty Publications

This paper considers the problem of reorienting a constellation of spacecraft such that the fuel distributed across the constellation is both conserved and expended uniformly. Results are derived for constellations with an arbitrary number of spacecraft, assuming that the constellation is in free space, that the spacecraft mass is time invariant, and that the thrusters can produce thrust in any direction. An open-loop control algorithm is derived by minimizing a cost function that trades off total fuel minimization and fuel equalization. The associated optimization problem is shown to be amenable to standard algorithms. Simulation results using a four-spacecraft constellation are …

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Invitation To An Enterprise: From Physics To World History To The Study Of Civilizations, Arthur Iberall, Frank Hassler, Harry Soodak, David Wilkinson Apr 2000

Invitation To An Enterprise: From Physics To World History To The Study Of Civilizations, Arthur Iberall, Frank Hassler, Harry Soodak, David Wilkinson

Comparative Civilizations Review

No abstract provided.

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The Character Of Ash Deposits And The Thermal Performance Of Furnaces, T. F. Wall, S. P. Bhattacharya, Larry Lin Baxter 8507091, G. Richards, J. N. Harb Mar 2000

The Character Of Ash Deposits And The Thermal Performance Of Furnaces, T. F. Wall, S. P. Bhattacharya, Larry Lin Baxter 8507091, G. Richards, J. N. Harb

Faculty Publications

The character of fireside ash deposits depend on the processes by which deposits are formed and subsequent reactions within the deposit and with furnace gases. The properties influencing furnace heat transfer, absorptivity for radiative transfer and thermal conductivity for conductive transfer are shown from many measurements to depend on this character. Illustrative trends in these properties as deposits mature and grow are presented together with their effect on furnace exit temperature and efficiency. The reflective character of initial deposits from particular coals is then considered with predictions and measurements of the spectral character of such deposits, during the first three …

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Full Issue Mar 2000

Full Issue

Inscape

No abstract provided.

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November First, One A.M., Brian Jackson Mar 2000

November First, One A.M., Brian Jackson

Inscape

No abstract provided.

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Designing Human-Centered Automation: Tradeoffs In Collision Avoidance System Design, Michael A. Goodrich, Erwin R. Boer Mar 2000

Designing Human-Centered Automation: Tradeoffs In Collision Avoidance System Design, Michael A. Goodrich, Erwin R. Boer

Faculty Publications

Technological advances have made plausible the design of automated systems that share responsibility with a human operator. The decision to use automation to assist or replace a human operator in safety-critical tasks must account for not only the technological capabilities of the sensor and control subsystems, but also the autonomy, capabilities, and preferences of the human operator. By their nature, such human-centered automation problems have multiple attributes: an attribute reflecting human goals and capabilities, and an attribute reflecting automation goals and capabilities. Although good theories exist that describe portions of human behavior generation, in the absence of a general theory …

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Alternate Path Routing For Multicast, Daniel Zappala Mar 2000

Alternate Path Routing For Multicast, Daniel Zappala

Faculty Publications

Alternate path routing has been well-explored in telecommunication networks as a means of decreasing the call blocking rate and increasing network utility. However, aside from some work applying these concepts to unicast flows, alternate path routing has received little attention in the Internet community. We describe and evaluate an architecture for alternate path routing for multicast flows. For path installation, we design a receiver-oriented alternate path protocol and prove that it reconfigures multicast trees without introducing loops. For path computation, we propose a scalable local search heuristic that allows receivers to find alternate paths using only partial network information. We …

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Managing Temporal Data In A Comprehensive Modeling Environment, Norman L. Jones, E. James Nelson, Colby T. Manwaring Mar 2000

Managing Temporal Data In A Comprehensive Modeling Environment, Norman L. Jones, E. James Nelson, Colby T. Manwaring

Faculty Publications

Numerous graphical pre- and post-processors have been developed for numerical modeling. Many of these systems support numerical models that can be used for both steady state and transient simulations. Dealing with transient data can be particularly difficult in such an environment due to the differing time scales and units associated with transient field data and boundary conditions. A data model and a set of functions are presented in this paper as a simple, yet powerful strategy for managing temporal data in a comprehensive modeling environment. The strategy makes it possible to seamlessly integrate multiple types of transient data and convert …

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Pulsed Ultrasound Enhances The Killing Of Escherichia Coli Biofilms By Aminoglycoside Antibiotics In Vivo, Andrea M. Rediske, Beverly L. Roeder, Jared L. Nelson, Rachel L. Robison, Bruce Schaaije, Richard A. Robison, William G. Pitt Mar 2000

Pulsed Ultrasound Enhances The Killing Of Escherichia Coli Biofilms By Aminoglycoside Antibiotics In Vivo, Andrea M. Rediske, Beverly L. Roeder, Jared L. Nelson, Rachel L. Robison, Bruce Schaaije, Richard A. Robison, William G. Pitt

Faculty Publications

Escherichia coli biofilms on two polyethylene disks were implanted subcutaneously into rabbits receiving systemic gentamicin. Ultrasound was applied for 24 h to one disk. Both disks were removed, and viable bacteria were counted. Pulsed ultrasound significantly reduced bacterial viability below that of nontreated biofilms without damage to the skin.

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Modeling The Statistical Time And Angle Of Arrival Characteristics Of An Indoor Multipath Channel, Michael A. Jensen, Brian D. Jeffs, A. Lee Swindlehurst, Quentin H. Spencer Mar 2000

Modeling The Statistical Time And Angle Of Arrival Characteristics Of An Indoor Multipath Channel, Michael A. Jensen, Brian D. Jeffs, A. Lee Swindlehurst, Quentin H. Spencer

Faculty Publications

Most previously proposed statistical models for the indoor multipath channel include only time of arrival characteristics. However, in order to use statistical models in simulating or analyzing the performance of systems employing spatial diversity combining, information about angle of arrival statistics is also required. Ideally, it would be desirable to characterize the full spare-time nature of the channel. In this paper, a system is described that was used to collect simultaneous time and angle of arrival data at 7 GHz. Data processing methods are outlined, and results obtained from data taken in two different buildings are presented. Based on the …

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Full Issue Feb 2000

Full Issue

Swiss American Historical Society Review

No abstract provided.

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Initial Negotiations, Donald Tritt, Erdmann Schmocker, Leo Schelbert, R. Steven Wisdom, Kent Anderson Feb 2000

Initial Negotiations, Donald Tritt, Erdmann Schmocker, Leo Schelbert, R. Steven Wisdom, Kent Anderson

Swiss American Historical Society Review

Initiation of a Potential SAHS Swiss American Center (SAC) Project: From the Minutes of the SAHS Annual Meeting, held on October 10, 1998 at the Embassy of Switzerland in Washington, D. C., Dr. Sabine. Jessner, Secretary: "Donald Tritt asked the members to consider the creation of a Swiss American Center to preserve and foster Swiss-American culture. He had literature on ethnic centers created by Americans of Danish, Norwegian, Irish, and other ethnic backgrounds. A Swiss Center might include museum exhibition space, meeting facilities, a library, and an archive. Discussion followed. This possibility met with enthusiastic response. Among those speaking in …

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Electronic Structure Of Cu1-Xnixrh2s4 And Curh2se4: Band-Structure Calculations, X-Ray Photoemission, And Fluorescence Measurements, Gus L. W. Hart, W. E. Pickett, E. Z. Kurmaev, M. Neumann, D. Hartmann, A. Moewes, D. L. Ederer, R. Endoh, K. Taniguchi, S. Nagata Feb 2000

Electronic Structure Of Cu1-Xnixrh2s4 And Curh2se4: Band-Structure Calculations, X-Ray Photoemission, And Fluorescence Measurements, Gus L. W. Hart, W. E. Pickett, E. Z. Kurmaev, M. Neumann, D. Hartmann, A. Moewes, D. L. Ederer, R. Endoh, K. Taniguchi, S. Nagata

Faculty Publications

The electronic structure of spinel-type Cu1-xNixRh2S4 (x=0.0, 0.1, 0.3, 0.5, 1.0) and CuRh2Se4 compounds has been studied by means of x-ray photoelectron (SPS) and fluorescent spectroscopy. Cu L3, Ni L3, S L2,3, and Se M2,3 x-ray emission spectra (XES) were measured near thresholds at Beamline 8.0 of the Lawrence Berkeley Laboratory's Advanced Light Source. XES measurements of the constituent atoms of these compounds, reduced to the same binding energy scale, are found to be in excellent agreement with XPS valence bands. The calculated XES spectra which include dipole matrix elements show that the partial density of states reproduce experimental spectra …

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Storytellers: Scandinavian's Art Told Of Restoration, J. Michael Hunter Jan 2000

Storytellers: Scandinavian's Art Told Of Restoration, J. Michael Hunter

Faculty Publications

Missionary work in Scandinavia began 150 years ago with the arrival of the first LDS missionaries in Denmark on June 14, 1850. In keeping with the observance of the sesquicentennial of the Scandinavian Mission, the Church News presents this article by J. Michael Hunter about two prominent Latter-day Saint artists from earlier days in that part of the world. The art and work of Carl Christian Anton Christensen (1831-1921) from Denmark and Danquart Anton Weggeland (1827-1918) from Norway are discussed, focusing on their use of art to tell stories. Images of their art accompany the article.

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