Physical Sciences and Mathematics Commons^™

Object-Oriented Modeling And Fauly Detection Of A Powder Feeder For A Laser Metal Deposition System, Robert G. Landers, Michael Gene Hilgers, Frank W. Liou, Bruce M. Mcmillin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

One of the most critical components of a laser metal deposition system is the powder feeder unit. Techniques are required to efficiently design and analyze these systems and to ensure fault tolerance during the operation. In this paper, a model of the powder feeder unit, based on object- oriented abstractions of it components, is developed. This model is modular in that specific components can be efficiently updated or replaced with components that perform a similar function. In addition, the model can be used for simulation allowing for efficient design and analysis. Assurance of the correctness of the powder feeder system …

Observations Of Persistent Leonid Meteor Trails 3. The ‘‘Glowworm’’, Jack D. Drummond, Brent W. Grime, Chester S. Gardner, Alan Z. Liu, Xinzhao Chu, Michael C. Kelley, Craig Kruschwitz, Timothy J. Kane

Physical Sciences - Daytona Beach

A spectacular, well-observed Leonid meteor of visual magnitude -14.3 appeared on 17 November 1998 and left a lingering trail, dubbed the Glowworm, that was well studied. From a location on Kirtland Air Force Base, near Albuquerque, New Mexico, we obtained CCD images of the trail from 94 to 203 s after the meteor and recorded a video with an intensified camera for even longer. From information obtained with a sodium lidar half an hour after the meteor, we have determined that a gravity wave with a vertical wavelength of 2.4 km was responsible for the right-angled appearance of the trail. …

A Regional Gis-Based Analysis Of Elk Habitat Suitability In Northwestern Nebraska, Justin W. Fischer

School of Natural Resources: Dissertations, Theses, and Student Research

The need to accurately assess the use and suitability of elk (Cervus elaphus spp.) habitat at regional scales will continue to increase as human development encroaches into what was once optimum elk habitat. The objectives of this research were to calculate the relative proportions of habitat use by elk in the Pine Ridge region of Northwestern Nebraska from a set of radio-collared elk locations and generate a habitat suitability model. Habitat variables (Iandcover type, aspect, slope, distance to a road, road density, and distance from the ponderosa pine edge) were measured for each elk location (n = 5,787 dating …

A Regional Gis-Based Analysis Of Elk Habitat Suitability In Northeast Nebraska, J W. Fisher

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Effectiveness Of Frightening Devices For Reducing Deer Damage In Cornfields, Jason M. Gilsdorf

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Influence Of Light And Nutrients On Atrazine Toxicity To Freshwater Algae, Crystal J. Hansen

School of Natural Resources: Dissertations, Theses, and Student Research

No abstract provided.

Water Current, Volume 34, No. 4. August 2002

Water Current Newsletter

• Summer Tour Attracts More Than 80 by Steve Ress

• From the Director

• Meet the Faculty

• We All Live Within One System by Mary Harding

• Has the Time Come To Look at Urban Stormwater Differently? By Glenn D. Johnson

• Mapping Groundwater Recharge for Nebraska

• Nebraska Water Marketing Policy Choices by J. David Aiken

• Water News Briefs

• A Union of Festibal of Color and Gardener’s Gala by Steve Ress

Polymer-Supported 14-Crown-4 And Bifunctional Resins For Selective Metal Ion Complexation: Synthesis And Characterization, Christy L. Stine

Doctoral Dissertations

Polymer-supported 14-crown-4 and bifunctional resins containing amine and phosphonate ester ligands were synthesized and characterized. Complexation studies were performed to evaluate the metal ion selectivity of the resins.

The immobilization of 14-crown-4 onto crosslinked polymer supports for the complexation of Li(l) from aqueous solutions was studied. M any methods were attempted, but etherification of the hydroxymethyl form of 14-crown-4 was found to be the most successful. The polymers examined were poly(vinylbenzyl chloride), poly(vinylbenzyl chloride)-co-acrylamide and poly(glycidyl methacrylate). The amount of Li(l) complexed by the crown ether supported polymers was affected by the polarity (i.e., hydrophilicity) of the polymer matrix. The …

Magnetic Properties Of Nanoparticle Systems Of Fe, Co, Ni, And Fept, Created By Ion Implantation, Korey Dean Sorge

Doctoral Dissertations

Magnetization measurements have been performed on nanoparticle arrays of Fe, Co, Ni, and FePt in single-crystal substrates. Materials are formed by ion implantation into a layer followed by thermal annealing to give electrically isolated but crystallographically textured arrays. Studies show competition between effective single-particle anisotropy (due to magnetocrystalline, shape, surface, and stress effects) and macroscopic anisotropy due to dipolar interactions.

Results of these measurements are compared to expectations found in the well-known Stoner-Wohlfarth model of non-interacting, uniaxial particles. While this model is extensively used in magnetic materials research, the missing effects from dipolar interactions between particles give very different results …

Poet: The Online Preference Elicitation Tool, James Royalty, Robert Holland, Judy Goldsmith, Alex Dekhtyar

Computer Science and Software Engineering

If the goal of eliciting accurate user preferences over a complex value space is to be realized, the elicitation process must be through while at the same time not overly burdensome to the user. An ideal preference elicitation tool would maximize the information about preferences acquired from the user while minimizing the number of queries required. To this end, we present POET: the Online Preference Elicitation Tool.
POET is a graphical Java applet designed to elicit complex preference structures to form a utility function. Once the elicitation process is complete POET outputs the resulting utility function as an XML …

Size And Structure Of The Narrow-Line Region Of Quasars, Nicola Bennert, Heino Falcke, Hartmut Schulz, Andrew S. Wilson, Beverley J. Wills

Physics

We have observed the narrow-line regions (NLRs) of the seven brightest radio-quiet Palomar-Green (or Bright Quasar Survey) quasars (z < 0.5) with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST). Linear-ramp filters were used to image the [O III] λ5007 line emission with 00455-01 pixel resolution. We find that the NLRs are very compact with typical extents of 2''-4''. Two quasars show compact filamentary structures similar to Seyfert NLRs. They may be related to radio outflows. Most interestingly, when including a sample of Seyfert galaxies observed with HST, we tentatively find that the size of the NLR is proportional to the square root …

Reseeding Of Grazing Gastropods And Bivalves Into The Marine Environment In Western Australia, Jane Borg

Fisheries management papers

The Department of Fisheries does not want to embark on what is ‘new territory’ in Western Australia without a policy framework to define what is to happen, why it is to happen, and what will happen if the project does or does not succeed. This paper therefore attempts to do three things. 1. It sets in place accepted definitions of reseeding and stock enhancement within the general context of fisheries management in Western Australia. 2. It discusses the policy issues associated with reseeding grazing gastropods and bivalves into the natural environment. 3. It proposes a framework or process to be …

Summer 2002, Nsu Oceanographic Center

Currents

No abstract provided.

Spin Injection Into Amorphous Semiconductors, Evgeny Y. Tsymbal, V. M. Burlakov, Ivan I. Oleinik

Evgeny Tsymbal Publications

Using a realistic model for the atomic and electronic structure of amorphous silicon, we explore spin injection into amorphous semiconductors. We calculate the spin-dependent conductance of magnetoresistive devices within the Landauer-Büttiker formalism including inelastic scattering. We find that reducing the density of injected carriers and increasing the spin polarization of the electrodes are favorable for spin injection, whereas inelastic scattering is detrimental, and show that the upper limit for magnetoresistance is given by Julliere's formula.

Gradient Recovery And A Posteriori Estimate For Bilinear Element On Irregular Quadrilateral Meshes, Zhimin Zhang

Mathematics Research Reports

A polynomial preserving gradient recovery method is proposed and analyzed for bilinear element under general quadrilateral meshes. It has been proven that the recovered gradient converges at a rate O(h^{1+rho) for rho = min(alpha, 1) when the mesh is distorted O(h1+alpha) (alpha > 0) from a regular one. Consequently, the a posteriori error estimator based on the recovered gradient is asymptotically exact.}

Medusae Fossae Formation: New Perspectives From Mars Global Surveyor, Bethany Bradley, S. E.H Sakimoto, H. Frey, J. R. Zimbelman

Bethany Bradley

The nature and origin of the Medusae Fossae Formation (MFF) on Mars has been debated since the return of the first Viking images. The MFF's young age, distinctive surface texture, and lack of obvious source have prompted multiple hypotheses for its origin. This study uses data from the Mars Global Surveyor (MGS) mission to examine the MFF at all available scales. We discuss and quantify observations from Mars Orbiter Laser Altimeter (MOLA) topography and Mars Orbiter Camera (MOC) images to better constrain the origin of the MFF. Topographic grid estimates yield a present extent of 2.1 × 106 km2 and …

Spectral Properties Of He And Heavy Ions In ³He-Rich Solar Flares, Glenn M. Mason, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

Using advanced instrumentation on the ACE spacecraft, we have conducted a survey of solar energetic particle spectra in ³He-rich events over a broad energy range ∼80 keV nucleon-1 to 15 MeV nucleonˉ¹ during the period 1997 September-2001 March. The spectra of ⁴He and heavy ions (C, N, O, Ne, Mg, Si, S, Ca, Fe) were generally similar over this range but often hardened below ∼1 MeV nucleonˉ¹. In most of the events there was even stronger hardening of the ³He spectrum below ∼1 MeV nucleonˉ¹, leading to an energy-dependent ³He: ⁴He ratio. These observations point to unique and distinct properties …

Competition Between Ferromagnetic Metallic And Paramagnetic Insulating Phases In Manganites, G. Li, H. D. Zhou, S. J. Feng, Xiaojuan Fan, X. G. Li, Z. D. Wang

Physics Faculty Research

La_0.67Ca_0.33Mn_1−xCu_xO₃(x=0 and 0.15) epitaxial thin films were grown on the (100) LaAlO₃ substrates, and the temperature dependence of their resistivity was measured in magnetic fields up to 12 T by a four-probe technique. We found that the competition between the ferromagnetic metallic (FM) and paramagnetic insulating (PI) phases plays an important role in the observed colossal magnetoresistance(CMR) effect. Based on a scenario that the doped manganites approximately consist of phase-separated FM and PI regions, a simple phenomenological model was proposed to describe the CMR effect. Using this model, we …

Chromospherically Active Stars. Xxi. The Giant, Single-Lined Binaries Hd 89546 And Hd 113816, Francis C. Fekel, Gregory W. Henry, Joel A. Eaton, Julius Sperauskas, Douglas S. Hall

Information Systems and Engineering Management Research Publications

We have obtained spectroscopy and photometry of the chromospherically active, single-lined spectroscopic binaries HD 89546 and HD 113816. HD 89546 has a circular orbit with a period of 21.3596 days. Its primary has a spectral type of G9 III and is somewhat metal-poor with [Fe/H]~-0.5. HD 113816 has an orbit with a period of 23.6546 and a low eccentricity of 0.022. Its mass function is extremely small, 0.0007 Msolar, consistent with a very low inclination. The primary is a slightly metal-poor K2 III. A decade or more of photometric monitoring with an automatic telescope demonstrates that both systems display brightness …

Optimal Path Planning And The Fast Marching Method, J. J. Clark

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The problem of determining an optimal path for an object moving through some obstacle space presents several nontrivial subproblems. The foremost being the computational complexity that is involved and how to best deal with the associated large data volume. For example, a non-symmetric object moving in three dimensions possesses six degrees of freedom. This can lead to a computational grid that may easily be on the order of 10¹². Furthermore, for every point in the computational domain, several complex calculations must be performed. These include performing tests to determine if the object and obstacles intersect, and numerically solving …

On The (V,5,Λ)-Family Of Bhaskar Rao Designs, G. R. Chaudhry, M. Greig, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We establish that the necessary conditions for the existence of Bhaskar Rao designs of block size five are : i). λ(v - 1) ≡ 0 (mod 4) ii). λv(v - 1) ≡ 0 (mod 40) iii). 2|λ. We show these conditions are sufficient: for λ = 4 if v > 215, with 10 smaller possible exceptions and one definite exception at v = 5; for λ = 10 if v > 445, with 11 smaller possible exceptions, and one definite exception at v = 5; and for λ = 20, with the possible exception of v = 32; we also give a …

Necessary And Sufficient Conditions For Three And Four Variable Orthogonal Designs In Order 36, S. Georgiou, C. Koukouvinos, M. Mitrouli, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We use a new algorithm to find new sets of sequences with entries from {0, ±a, ±b, ±c, ±d}, on the commuting variables a, b, c, d, with zero autocorrelation function. Then we use these sequences to construct a series of new three and four variable orthogonal designs in order 36. We show that the necessary conditions plus (.s1, s2, s3, s4) not equal to 12816 18 816 221313 26721 36 816 4889 12825 191313 23 424 289 9 381015 8899 14425 22 916 are sufficient for the existence of an OD(36; s1, s2 s3, s4) constructed using four circulant …

Similarity Join For Low- And High-Dimensional Data, Dmitri V. Kalashnikov, Sunil Prabhakar

Department of Computer Science Technical Reports

No abstract provided.

On Efficient On-Line Grouping Of Flows With Shared Bottlenecks At Loaded Servers, Ossama Younis, Sonia Fahmy

Department of Computer Science Technical Reports

No abstract provided.

Construction And Testing Of A Low-Finesse Fabry-Perot Interferometer For Use In Atomic Spectroscopy, Nathan C. Moody

Student Works

I built a low-finesse confocal cavity with aluminum mirrors for use in the imaging of ultra-cold calcium ion plasmas. The confocal cavity provides stability at large mirror separations, a condition necessary for achieving both low finesse and narrow peak widths. Additionally, the finesse in the case of coherent input is effectively doubled compared to multi-mode resonance. The cavity was tested using a GaN diode laser input at 397nm. The transmission obtained indicated that the finesse of the cavity was slightly lower than the prediction based on measurements of the mirror reflectivities and the assumption of incoherent input.

Magnetism Of Co Nanocluster Films, Y. Qiang, R.F. Sabiryanov, Sitaram Jaswal, Yi Liu, H. Haberland, David J. Sellmyer

David Sellmyer Publications

A cluster-beam technique is used to produce nearly monodispersed nanoclusters of Co while independently varying their size and concentration. The Co clusters are embedded in Cu and SiO₂ to form films with cluster size varying from 300 to 9000 atoms and Co concentration varying from 10 to 50 vol %. The Co magnetization (M_s) increases with increasing cluster size and decreases with increasing Co concentration for a given cluster size but is always less than the bulk value. First-principles calculations are used to analyze the experimental data in terms of the local environment effects at the …

Poly(Methyl Methacrylate) Synthetic Grit Formulations Sustain The Delivery Of Nicarbazin, A Contraceptive Agent, In Pest Waterfowl, Jerome C. Hurley, John J. Johnston

United States Department of Agriculture Wildlife Services: Staff Publications

Sixty-three mallards were fed one of ten poly(methyl methacrylate) based synthetic grit formulations containing varying concentrations of a proposed wildlife contraceptive (nicarbazin), plasticizer (acetyl tributylcitrate) and/or cross-linking agent (1,4-butanediol diacrylate). Release characteristics of the contraceptive agent were monitored for the purpose of developing a contraceptive formulation for control of pest waterfowl in urban settings. The addition of plasticizer increased the erosion rate (t_1/2=0.97-2.85 days), cross-linking the polymer matrix slightly decreased the erosion rate (t_1/2=4.45-5.05 days) and increasing the concentration of the contraceptive agent increased the erosion rate (t_1/2= 3 . 3 …

Basis Of The Ce-Qual-W2 Version 3 River Basin Hydrodynamic And Water Quality Model, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

CE-QUAL-W2 Version 3, a 2-D (longitudinal-vertical) hydrodynamic and water quality model for river basins combining both river and stratified river-estuary and lake-reservoir flow, is a development product of the Waterways Experiment Station in Vicksburg, MS, USA. With the development and release of any revised or reformulated model codes, significant model validation is required. This includes comparison of model results to simple analytical solutions for hydrodynamics and water quality transport, as well as comparison to laboratory and field data. In this paper, the model is compared to numerous analytical solutions for mass transport (1- D advective mass transport) and hydrodynamics (impulsive …

The Bull Run River–Reservoir System Model, Robert Leslie Annear, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

The Bull Run watershed is located 41.8 kilometers east of Portland, Oregon in the Mt. Hood National Forest and consists of two reservoirs supplying drinking water to over 840,000 people in the Portland metropolitan area. In March 1998 Steelhead and Spring Chinook were listed as threatened in the Lower Columbia basin under the Endangered Species Act. Historical reservoir operations during the summer released no water downstream resulting in stream temperatures exceeding the state water quality standard for salmonids. CE-QUAL-W2 Version 3 is a two-dimensional water quality and hydrodynamic model capable of modeling watersheds with interconnected rivers, reservoirs and estuaries. CE-QUAL-W2 …

Visualization Methods: A Comparative Study Of New, Traditional And Robust Procedures, Kimberly Crimin

Dissertations

Two major goals in discriminant analysis are discrimination and classification. In discrimination, the goal is to describe graphically (visualization) different features of several known groups. In classification, the goal is to allocate unknown observations to one of several known groups. We have developed new visualization procedures based on traditional estimating procedures and also on robust estimating procedures. We have further developed robust classification procedures. We propose several robust classification procedures based on coordinatewise and affine equivariant, rank-based robust estimates. Empirical studies are performed over many different error distributions. These studies result in empirical efficiencies of the robust and traditional procedures. …