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Totally Nonnegative Matrices, Shaun M. Fallat
Totally Nonnegative Matrices, Shaun M. Fallat
Dissertations, Theses, and Masters Projects
An m-by-n matrix A is called totally nonnegative (resp. totally positive) if the determinant of every square submatrix (i.e., minor) of A is nonnegative (resp. positive). The class of totally nonnegative matrices has been studied considerably, and this class arises in a variety of applications such as differential equations, statistics, mathematical biology, approximation theory, integral equations and combinatorics. The main purpose of this thesis is to investigate several aspects of totally nonnegative matrices such as spectral problems, determinantal inequalities, factorizations and entry-wise products. It is well-known that the eigenvalues of a totally nonnegative matrix are nonnegative. However, there are many …
Dynamic Load Balancing Via Thread Migration, David Cronk
Dynamic Load Balancing Via Thread Migration, David Cronk
Dissertations, Theses, and Masters Projects
Light-weight threads are becoming increasingly useful for parallel processing. This is particularly true for threads running in a distributed memory environment. Light-weight threads can be used to support latency hiding techniques, communication and computation overlap, and functional parallelism. Additionally, dynamic migration of light-weight threads supports both data locality and load balancing. Designing a thread migration mechanism presents some very unique and interesting challenges. One such challenge is maintaining communication between mobile threads. A potentially more difficult challenge involves maintaining the correctness of pointers within mobile threads. Since traditional pointers have no concept of address space, moving threads from processor to …
Additives For Increased Atomic Oxygen Resistance In Cyanate Ester Resins, Sandeep Amar Saggar
Additives For Increased Atomic Oxygen Resistance In Cyanate Ester Resins, Sandeep Amar Saggar
Dissertations, Theses, and Masters Projects
No abstract provided.
Sediment Dispersal And Sequence Development Along A Tectonically Active Margin: Late Quaternary Evolution Of The Ganges-Brahmaputra River Delta, Steven Lee Goodbred Jr.
Sediment Dispersal And Sequence Development Along A Tectonically Active Margin: Late Quaternary Evolution Of The Ganges-Brahmaputra River Delta, Steven Lee Goodbred Jr.
Dissertations, Theses, and Masters Projects
Situated in the Bengal Basin, the Ganges-Brahmaputra river delta comprises one of the largest fluviodeltaic systems in the world, comprising ∼ 100,000 km2 of floodplain and delta plain and a 40,000 km2 subaqueous delta on the shelf. Sediment load of the Ganges-Brahmaputra river is 109 t/yr, and seasonal flooding may inundate >70% of the delta during large events. Active tectonic processes have resulted in both uplift and subsidence in this structurally complex region. These general characteristics suggest that the Ganges-Brahmaputra delta represents a heretofore undescribed delta end-member, forming along a high-yield, high-energy, tectonically active margin. to investigate this view, stratigraphic, …
Limits To Parallelism In Scientific Computing, Dan Alvin Chrisman Jr.
Limits To Parallelism In Scientific Computing, Dan Alvin Chrisman Jr.
Dissertations, Theses, and Masters Projects
The goal of our research is to decrease the execution time of scientific computing applications. We exploit the application's inherent parallelism to achieve this goal. This exploitation is expensive as we analyze sequential applications and port them to parallel computers. Many scientifically computational problems appear to have considerable exploitable parallelism; however, upon implementing a parallel solution on a parallel computer, limits to the parallelism are encountered. Unfortunately, many of these limits are characteristic of a specific parallel computer. This thesis explores these limits.;We study the feasibility of exploiting the inherent parallelism of four NASA scientific computing applications. We use simple …
Experimental And Computational Techniques In Carbon-13 Nmr, Samuel John Varner
Experimental And Computational Techniques In Carbon-13 Nmr, Samuel John Varner
Dissertations, Theses, and Masters Projects
An efficient method for calculating NMR lineshapes from anisotropic second rank tensor interactions is presented. The algorithm produces lineshapes from asymmetric tensors by summing those from symmetric tensors. This approach significantly reduces the calculation time, greatly facilitating iterative nonlinear least squares fitting of experimental spectra. This algorithm has been modified to produce partially relaxed lineshapes and spectra of partially ordered samples.;Calculations for rapidly spinning samples show that spin-lattice relaxation time ( T1Z ) anisotropy varies with the angle between the spinning axis and the external field. When the rate of molecular motion is in the extreme narrowing limit, measurement of …
Multi-Image Classification And Compression Using Vector Quantization, Beverly J. Thompson
Multi-Image Classification And Compression Using Vector Quantization, Beverly J. Thompson
Dissertations, Theses, and Masters Projects
Vector Quantization (VQ) is an image processing technique based on statistical clustering, and designed originally for image compression. In this dissertation, several methods for multi-image classification and compression based on a VQ design are presented. It is demonstrated that VQ can perform joint multi-image classification and compression by associating a class identifier with each multi-spectral signature codevector. We extend the Weighted Bayes Risk VQ (WBRVQ) method, previously used for single-component images, that explicitly incorporates a Bayes risk component into the distortion measure used in the VQ quantizer design and thereby permits a flexible trade-off between classification and compression priorities. In …
Accurate Visualization Of Distributed System Execution, Dennis Lee Edwards
Accurate Visualization Of Distributed System Execution, Dennis Lee Edwards
Dissertations, Theses, and Masters Projects
The concurrent execution of processes in a distributed system makes the interactions between them difficult to understand. A clear image of the execution sequence that occurs as well as possible alternative scenarios is paramount to providing the software engineer the understanding needed to create reliable software.;In this thesis, we examine several representation methods of presenting a pictorial view of the execution of a distributed system and evaluate each in terms of three criteria. First, only those relationships that are created during the execution can and must be presented. Second, the presentation must be such that a reasonable amount of information …
Decay Search For The Supersymmetric R(0) (Gluon Gluino) Hadron Via The Channel R(0) Going To Positive Pion Negative Pion Photino, Kevin Michael Hern
Decay Search For The Supersymmetric R(0) (Gluon Gluino) Hadron Via The Channel R(0) Going To Positive Pion Negative Pion Photino, Kevin Michael Hern
Dissertations, Theses, and Masters Projects
There has been recent theoretical interest in supersymmetry breaking scenarios in which the gauginos are light compared to the squarks. One prediction of these light gluino models is the existence of the R 0 hadron (gg?£). Brookhaven National Laboratory AGS Experiment 935 (E935) searched for light gluinos through the appearance of pi+pi- pairs with invariant mass Mpipi > 545 MeV/c2 in a high flux neutral beam. The search has yielded one candidate event. This event is consistent with the anticipated background of 1.4 events due to interactions of neutrons in the beam with the residual gas in the evacuated decay region. …
Characterization Of The Physical Properties Of Iron Polyimide Nanocomposites, Russell A. Wincheski
Characterization Of The Physical Properties Of Iron Polyimide Nanocomposites, Russell A. Wincheski
Dissertations, Theses, and Masters Projects
The discovery of tunneling magneto-resistance has led to a great deal of interest in the study of ferromagnet-insulator-ferromagnet (FIF) systems due to potential sensor and magnetic storage applications. An analysis of the band structure of the 3d ferromagnets shows that the conduction electrons become spin polarized by the molecular field. The transmission coefficient of these electrons across a tunneling gap therefore depends upon the relative alignment of the molecular field between the two ferromagnets.;In this work the manufacture of such tunneling gaps through compression molding of powdered ferromagnetic iron with a high performance polyimide has been studied for the first …
Electroproduction Of Omega (783) Mesons Using Clas At Jefferson Lab, Alan Clayton Coleman
Electroproduction Of Omega (783) Mesons Using Clas At Jefferson Lab, Alan Clayton Coleman
Dissertations, Theses, and Masters Projects
Electroproduction of omega(783) mesons from a proton target has been measured in a search for so called "missing baryon resonances". A 4.0 GeV electron beam was used. The scattered electrons were measured in coincidence with the recoiling proton and the positive pion from the omega decay. Missing mass techniques were applied to identify the omega in the final state, and to reduce the rho(770) contribution. The data show the omega very clearly on a smooth background originating predominantly from three-pion phase space. Yields have been extracted, and the W and t dependencies determined. The t dependence is mostly monotonic for …
Thermoelastic And Photoelastic Full-Field Stress Measurement, Deonna Faye Woolard
Thermoelastic And Photoelastic Full-Field Stress Measurement, Deonna Faye Woolard
Dissertations, Theses, and Masters Projects
Photoelasticity is an optical technique that measures the difference of the principal stresses plus the principal stress direction. A complementary technique is thermoelasticity which measures the sum of the principal stresses. Combining these two full-field, non-contact nondestructive evaluation techniques allows the individual stress components to be measured. One of the main difficulties in merging these two measurement systems is in identifying an appropriate surface coating. Thermoelasticity demands a highly emissive surface, while photoelasticity requires a thick, stress-birefringent, transparent coating with a retro-reflective backing. Two coatings have been identified that can be used for combined thermoelastic and photoelastic stress measurements: PMMA …
Causal Distributed Assert Statements, Sharon J. Simmons
Causal Distributed Assert Statements, Sharon J. Simmons
Dissertations, Theses, and Masters Projects
Monitoring a program's execution is fundamental to the debugging, testing and maintenance phases of program development. This research addresses the issue of monitoring the execution of a distributed program. In particular, we are concerned with efficient techniques for evaluating global state predicates for distributed programs. The global state of a distributed program is not well-defined, making the monitoring task complex compared to that of a sequential programs. Processes of a distributed program execute concurrently, and the events of the program cannot be totally ordered. Each process has its own local memory, and the local memories are physically separate.;Despite the difficulties …
A Two-Component Aggregation Model, Thomas A. Chisholm Jr
A Two-Component Aggregation Model, Thomas A. Chisholm Jr
Dissertations, Theses, and Masters Projects
An aggregation model which allows specification of primary particle size, density, and fractal dimension for two different particle types was written. Three stickiness values are used, the stickiness of each particle type to itself and the stickiness between particle types. Aggregation mechanisms considered include differential settling and turbulent shear. The model is used in three forms. In its simplest form, it operates on a closed system with aggregates breaking up when their size approaches the Kolmogorov scale. If the system begins with two types of primary particles, larger aggregates have uniform composition. A second version of the model includes removal …
Fine-Scale Strata Formation In Biologically And Physically Dominated Estuarine Systems Within The Lower Chesapeake And York River Subestuary, Timothy M. Dellapenna
Fine-Scale Strata Formation In Biologically And Physically Dominated Estuarine Systems Within The Lower Chesapeake And York River Subestuary, Timothy M. Dellapenna
Dissertations, Theses, and Masters Projects
To investigate the relationship between biological and physical mixing in forming strata, the lower mainstem of Chesapeake Bay has been contrasted with the York River Subestuary. By using radioisotope profiles from sediment cores, comparisons are made in terms of depth and rate of sediment mixing, deposition and accretion. Within the lower Chesapeake Bay two sites were selected as biologically dominated, both are located within the bay stem plains and are characterized by muddy sand and an abundance of large, deep-dwelling organisms. X-radiographs indicate complete biological reworking of sediments. 210Pb profiles reveal low sediment accretion rates within the mainstem sites ( …
Limitation Of Bacterial Growth By Dissolved Organic Matter And Iron In The Southern Ocean, Matthew J. Church
Limitation Of Bacterial Growth By Dissolved Organic Matter And Iron In The Southern Ocean, Matthew J. Church
Dissertations, Theses, and Masters Projects
No abstract provided.
Habitat Fragmentation In Transplanted Eelgrass (Zostera Marina) Beds: Effects On Decapods And Fish, Alfonso Vollmer Lombana
Habitat Fragmentation In Transplanted Eelgrass (Zostera Marina) Beds: Effects On Decapods And Fish, Alfonso Vollmer Lombana
Dissertations, Theses, and Masters Projects
No abstract provided.
Functional And Molecular Analysis Of Antibody Affinity Maturation In Rainbow Trout (Oncorhynchus Mykiss), Haili Zhang
Functional And Molecular Analysis Of Antibody Affinity Maturation In Rainbow Trout (Oncorhynchus Mykiss), Haili Zhang
Dissertations, Theses, and Masters Projects
No abstract provided.
Geochemistry Of Small Mountainous Rivers Of Papua New Guinea: Local Observations And Global Implications, Megan B. Raymond
Geochemistry Of Small Mountainous Rivers Of Papua New Guinea: Local Observations And Global Implications, Megan B. Raymond
Dissertations, Theses, and Masters Projects
Small, wet mountainous rivers (runoff > 0.63 m yr" 1 , headwater elevation> 1000 m, basin area < 10,000 km2 ) contribute a disproportionate amount of sediment to the global ocean due to their steep high topography, erosive substrate, and often high precipitation. Scattered data have suggested a slight, but statistically insignificant, inverse relationship between total dissolved solid (TDS) yield (T km-2 yr-1 ) and basin area, but small to very small rivers (basin areas< 10,000 km2 ) have been poorly documented. To fill this data gap, as well as to elucidate possible links between weathering and basin hydrology, nine small wet mountainous rivers, basin areas 22 km2-2300 km2 , were sampled in late May 1997 in northeastern Papua New Guinea. TDS concentrations ranged from 75 to 148 mg L-1 , with no correlation to watershed area. The dissolved organic carbon (DOC) and particulate organic carbon (POC) values were low, with a mean DOC value of 135 f.Lmol L-1 ; POC values were lower, averaging 3lf.Lmol L- 1 • TDS data, combined with large wet mountainous river TDS data, demonstrate a significant inverse relationship between TDS yield and basin area. As a result, small wet mountainous rivers contribute a disproportionate amount of TDS, and have the highest TDS yields of any class of river. This observation is attributed to the high runoff of the sampled rivers (-2m yr-1 ), in addition to high rates of chemical weathering, which is facilitated by the erosive substrate and high rates of organic matter remineralization.
Spatial And Temporal Distributions Of Organic Matter And Polycyclic Aromatic Hydrocarbons (Pahs) In Surface Waters Of The York River, Va Estuary, Rebecca E. Countway
Spatial And Temporal Distributions Of Organic Matter And Polycyclic Aromatic Hydrocarbons (Pahs) In Surface Waters Of The York River, Va Estuary, Rebecca E. Countway
Dissertations, Theses, and Masters Projects
No abstract provided.
Diet Composition And Feeding Habits Of Large Striped Bass, Morone Saxatilis, In Chesapeake Bay, John F. Walter
Diet Composition And Feeding Habits Of Large Striped Bass, Morone Saxatilis, In Chesapeake Bay, John F. Walter
Dissertations, Theses, and Masters Projects
No abstract provided.
Carbon Production And Growth Physiology Of Heterotrophic Bacteria In A Subtropical Coral Reef Ecosystem, Peter Dylan Countway
Carbon Production And Growth Physiology Of Heterotrophic Bacteria In A Subtropical Coral Reef Ecosystem, Peter Dylan Countway
Dissertations, Theses, and Masters Projects
No abstract provided.
Medium- And Long-Term Changes In Fluvial Discharge To The Sea: The Yellow River Case Study, John J. Galler
Medium- And Long-Term Changes In Fluvial Discharge To The Sea: The Yellow River Case Study, John J. Galler
Dissertations, Theses, and Masters Projects
No abstract provided.
Molecular Phylogeny Of Lake Baikal Amphipods, Kenneth S. Macdonald
Molecular Phylogeny Of Lake Baikal Amphipods, Kenneth S. Macdonald
Dissertations, Theses, and Masters Projects
No abstract provided.
Indo-Pacific Population Structure Of The Black Marlin, Makaira Indica, Inferred From Molecular Markers, Brett Falterman
Indo-Pacific Population Structure Of The Black Marlin, Makaira Indica, Inferred From Molecular Markers, Brett Falterman
Dissertations, Theses, and Masters Projects
No abstract provided.
Sensory Development In Settlement-Stage Larvae Of Caribbean Labrids And Scarids: A Comparative Study With Implications For Ecomorphology And Life History Strategies, Monica R. Lara
Dissertations, Theses, and Masters Projects
The sensory capabilities of settlement-stage fishes are unknown but this information is necessary to studies of larval settlement and recruitment. The morphology of the cephalic lateral line, eye and external olfactory organ of thirteen species of settlement-stage Caribbean labroids was described. Scanning electron images of the cephalic lateral line neuromasts, lateral line canals and olfactory epithelia and histological studies of the retinae and morphological measurements of visual acuity were used to assess the level of sensory development attained at settlement. The sensory capabilities of settlement-stage fishes are discussed in relation to the possible cues settlement-stage fishes may be using to …
Fabrications And Characterizations Of Boron Containing Polyimides For Radiation Shielding, Christopher Scott Pugh
Fabrications And Characterizations Of Boron Containing Polyimides For Radiation Shielding, Christopher Scott Pugh
Dissertations, Theses, and Masters Projects
No abstract provided.
Artificial Societies: A Computational Approach To Studying Combat, Rachel J. Moore
Artificial Societies: A Computational Approach To Studying Combat, Rachel J. Moore
Dissertations, Theses, and Masters Projects
No abstract provided.
Turbulence In Binary Fluid Flow Systems: A Lattice Boltzmann Approach, Darren M. Wah
Turbulence In Binary Fluid Flow Systems: A Lattice Boltzmann Approach, Darren M. Wah
Dissertations, Theses, and Masters Projects
A method for simulating a turbulent binary fluid flow system based on the Lattice Boltzmann Method (LBM) is presented. The fluid equations up to the Navier-Stokes transport level are derived for this two fluid system, and results from numerical simulations using this method are shown. Finally, grid resolution is performed in a single fluid (LBM) simulation which determines the largest valid mesh size for a simulation that seeks to resolve physical structures of all scales.
A Comparison Of Size Selectivity And Relative Efficiency Of Sea Scallop Trawls And Dredges, David B. Rudders
A Comparison Of Size Selectivity And Relative Efficiency Of Sea Scallop Trawls And Dredges, David B. Rudders
Dissertations, Theses, and Masters Projects
No abstract provided.