Physical Sciences and Mathematics Commons^™

Plankton Transport Patterns And Residence Times Around A Tall Seamount: Simulation Results, Dorlisa Louise Hommel

OES Theses and Dissertations

A semi-spectral primitive equation circulation model was used to simulate flow over an isolated gaussian seamount. Model configuration was such that a Taylor Cap was generated in the flow over the seamount. Arrays of 100 drifters were released in the simulated flow fields at several depths (50, 100, 200, and 400 m) both upstream and over the seamount. For several experiments vertical behaviors were imposed on the drifters to simulate zooplankton migration patterns. The drifter simulations extended for three months. Drifter transport patterns were determined by the initial release position of the drifter relative to the Taylor Cap as well …

Ground Water Investigation Of The Petersburg Granite In Chesterfield County, Virginia, Michael W. Bennett

OES Theses and Dissertations

Yields of new water wells in areas underlain by the Petersburg Granite in Chesterfield County, Virginia should improve if procedures for site selection and well construction follow the new guidelines proposed. These guidelines integrate analyses of aerial photo linears and drainage patterns, survey of bedrock joints and shallow geophysical properties and techniques using several statistical methods.

Throughout the study area, fracture traces form in nearly the same orientation as bedrock fractures. The dominant N-S and E-W trending bedrock joints also corresponded to aerial photo linears of similar orientation.

Across one large fracture zone, both gamma-ray and electrical resistivity surveys reveal …

Fluid Inclusion Studies Of The Morefield Pegmatite Amelia County, Virginia, John Richard Smerekanicz

OES Theses and Dissertations

The Morefield Pegmatite is a planar, nearly vertical body situated in Grenville age gneisses and schists in the southeast Piedmont of Virginia. It consists of a mineralogically simple albite-quartz outer zone and a texturally and mineralogically complex inner zone of microcline-topaz-quartz, with trace amounts of rare-element minerals. Fluid inclusions in samples of quartz, topaz, beryl, spessartite and albite that span the length, width and depth of both zones can be classified by chemical composition into two main groups: H₂O-rich solutions and CO₂- H₂O -rich fluids. The H₂O -rich inclusions consist of H …

Interferences Of N-Chloroorganic Compounds In Free Chlorine Determination, Sushma H. Gandhi

Chemistry & Biochemistry Theses & Dissertations

Various N-chlorinated organic compounds give positive responses to the analytical methods used to determine free chlorine. The present work quantifies interferences due to N-chloroisoleucine, N-chloropiperidine and N-chloro-2-methylbutyraldiminein the free chlorine determination by amperometry. These N-chloroorganic compounds were also studied for the recovery in response by the indicator electrode in amperometric titrimetry. The total chlorine content of the chloroaldimines derived from the chlorination of the amino acids, alanine, glutamic acid, glycine, isoleucine, leucine, phenylalanine, serine, valine, and those of dipeptides, alanylvaline and glycylleucine, was determined by amperometry and DPD-FAS titrimetry. The two methods were compared and evaluated with respect to recovery …

Multiple Learner Systems Using Resampling Methods, Binyun Xie

Computer Science Theses & Dissertations

The N-Learners Problem deals with combining a number of learners such that the resultant system is "better", under some criterion, than the best of the individual learners. We consider a system of probably approximately correct concept learners. Depending on the available information, there are several methods to make the composite system better than the best of the individual learners. If a sample and an oracle that generates data points (but, not their classification) is available, then we show that we can achieve arbitrary levels of the normalized confidence of the composite system if (a) a robust learning algorithm is available, …

Visual Graphic Knowledge Management Methodology, Jih-Shih Hsu

Computer Science Theses & Dissertations

As computer technology evolves, graphic workstations are becoming more popular. They support more friendly user interfaces than do conventional terminals. The better user interfaces require more effort to develop. Therefore, many user interface (UI) design systems have been developed to facilitate the creation of modern user interfaces, but not very successfully. Many of them either provide limited features or are difficult to use. Besides, these UI design systems are actually like black boxes to their users because the underlying technology is opaque; their users cannot learn how to utilize the underlying window systems through user interface design sessions. In a …

Multigrid Algorithms For Massively Parallel Machines, Satyanarayan Gupta

Computer Science Theses & Dissertations

Numerical solutions of partial differential equations (pde's) are required in many physical problems arising in areas such as computational fluid dynamics, atmospheric sciences, electromagnetics etc. One of the most popular methods of solving pde's is the use of the multigrid algorithm. However, the implementation of the multigrid algorithm on massively parallel machines is not very efficient because of (i) low processor utilization and (ii) high communication overheads. These problems need to be addressed to make better use of massively parallel machines for solving pde's using the multigrid algorithm.

In this dissertation, we present three parallel multigrid algorithms which …

High Performance Issues On Parallel Architectures, Peter J. Looges

Computer Science Theses & Dissertations

In an effort to reduce communication latency in mesh-type architectures, these architectures have been augmented by various types of global and reconfigurable bus structures. The static bus structures provide excellent performance in many areas of computation especially structured numerical computations, but they lack the flexibility required of many large numerical and non-numerical applications. Reconfigurable bus systems have the dynamic adaptability to handle a much wider range of applications. While reconfigurable meshes can often yield constant time results for many problems, the cost of this performance is paid in the number of processors required. While in actuality the majority of these …

Mat Movement In Coastal Louisiana Marshes: Effect Of Salinity And Inundation On Vegetation And Nutrient Levels, Christopher Martin Swarzenski

Biological Sciences Theses & Dissertations

The present research compared and contrasted the physical structure of floating and rooted marshes, their differing responses to open-water salinities and inundation, as well as the nutrient distribution in the porewaters and sediment. The effects of the physical differences in the two marsh types on the ocurrence of the dominant emergent vegetation was discussed.

The main difference in physical structure of the two marsh types was the presence of a mineral, non-buoyant layer at 25-45 cm depth in the rooted marsh, which could serve as an anchor for the overlying highly organic mat layer found in both marsh types. Porewater …

Text-Independent Automatic Speaker Identification Using Partitioned Neural Networks, Laszlo Rudasi

Electrical & Computer Engineering Theses & Dissertations

This dissertation introduces a binary partitioned approach to statistical pattern classification which is applied to talker identification using neural networks. In recent years artificial neural networks have been shown to work exceptionally well for small but difficult pattern classification tasks. However, their application to large tasks (i.e., having more than ten to 20 categories) is limited by a dramatic increase in required training time. The time required to train a single network to perform N-way classification is nearly proportional to the exponential of N. In contrast, the binary partitioned approach requires training times on the order of N². …

Investigation Of Alignment Dynamics In Mg-Ne And Mg-Ar Two-Photon Fractional Collisions, David Allen Olsgaard

Physics Theses & Dissertations

A new technique is used to observe the dynamics of electronic alignment in a dissociating collision complex. The technique requires the absorption of two optical photons during a single binary collision. Two exciting light fields are tuned into the wings of the 3s¹s₀-3p₁ and 3p¹p₁-5s¹s₀ resonances of Mg where strong collisions with rare gas atoms induce transitions between corresponding molecular states. The alignment produced in the intermediate state by the first excitation is probed by the second laser as a function of relative linear laser polarization and laser …

Direct Measurement Of The Van Der Waals Interaction Between An Atom And Its Images In A Micron-Sized Cavity, V. Sandoghdar, C. I. Sukenik, E. A. Hinds, S. Haroche

Physics Faculty Publications

The authors have measured by laser spectroscopy the energy of interaction between a sodium atom and its images in the walls of a micron-sized cavity. This cavity-QED study is the first direct quantitative test of the Lennard-Jones van der Waals interaction as a function of controlled atom-surface separation and mean-square electric dipole moment.

Single Object Detection Using Multiple Sensors With Unknown Noise Distributions, Shaofen Chen

Computer Science Theses & Dissertations

We consider the design of an object classification system that identifies single objects using a system of sensors; each sensor outputs a random vector, according to an unknown (noise) probability distribution, in response to a sensed object. We consider a special class of systems, called the linearly separable systems, where the error-free sensor outputs corresponding to distinct objects can be mapped into disjoint intervals on real line. Given a set of sensor outputs corresponding to known objects, we show that a detection rule α_emp that approaches the correct rule with a high probability can be computed. We show …

Evaluation Of Late Mesozoic And Cenozoic Tectonism: Atlantic Inner Coastal Plain Margin Near Richmond, Virginia, Andrew A. Gremos

OES Theses and Dissertations

A combined geologic, geophysical, and geomorphic analysis of the Virginia Inner Coastal Plain margin near Richmond was conducted to investigate the presence of basement structures and to evaluate their influence on the overlying sedimentary package and present-day landscape. Basement structures identified included north-northeast and northwest oriented faults that appear to bound and transect a north-northeast trending early Mesozoic basin or basins and other pre-existing zones of weakness. Observed offsets are propagated upward through the pre-Miocene strata in the form of reverse faults and flexuring. Fracture sets measured in the Petersburg Granite and overlying Coastal Plain units, stream drainage lines, and …

Reasoning By Analogy In A Multi-Level System Architecture For The Design Of Mechanisms, Ghassan F. Issa

Computer Science Theses & Dissertations

Since the first attempts to integrate AI technology and engineering design nearly two decades ago, few expert systems have been shown to demonstrate sufficient reasoning capabilities to solve real-world design problems. The complex nature of design, the lack of understanding of the design process, and the limitations of current expert system technology have all been shown to have adverse effects on the maturity of this research area. Therefore, our direction in this research concentrates on understanding the design process, investigating a novel area of research focusing on creative design, and incorporating the results into a system model feasible for production …

Ring Dynamics In The Western Gulf Of Mexico, Adolphe W. Indest

OES Theses and Dissertations

The interaction of a recently-formed Loop Current ring and a fossil ring is studied using observations and a two-layered eddy-resolving general circulation model of the Gulf of Mexico. This interaction is investigated by following the evolution of volume, energy, potential vorticity, angular momentum and enstrophy within a model ring as it moves westward and encounters a fossil ring along the continental slope of the Gulf of Mexico. By comparing the model results with drifter and hydrographic data several new insights into ring/ring and ring/slope interactions are seen. A Loop Current ring may merge with a fossil ring along the slope. …

Monitoring Computer Systems: An Intelligent Approach, Myron Zhihong Xu

Computer Science Theses & Dissertations

Monitoring modern computer systems is increasingly difficult due to their peculiar characteristics. To cope with this situation, the dissertation develops an approach to intelligent monitoring. The resulting model consists of three major designs: representing targets, controlling data collection, and autonomously refining monitoring performance. The model explores a more declarative object-oriented model by introducing virtual objects to dynamically compose abstract representations, while it treats conventional hard-wired hierarchies and predefined object classes as primitive structures. Taking the representational framework as a reasoning bed, the design for controlling mechanisms adopts default reasoning backed up with ordered constraints, so that the amount of data …

Search For The Mössbauer Effect In 109ag, Shokrollah Rezaie-Serej

Physics Theses & Dissertations

The 88-keV first-excited nuclear state in ¹⁰⁹Ag has a mean lifetime of 57.1 sec and a corresponding natural linewidth of 1.15 x 10^-17 eV which is nearly six orders of magnitude narrower than the width for the 93-keV 13.2-μsec state in ⁶⁷Zn. The 93-keV transition in ⁶⁷Zn has the narrowest linewidth for which the Mossbauer effect has been observed. The 88-keV transition in ¹⁰⁹Ag is obviously a very difficult case for the observation of the Mossbauer effect and provides a stringent test for exploring the practical limits of inhomogeneous line broadening in real single …

Some Solutions To A Lens Model With Applications To Warm-Core Eddies, Juping Liu

OES Theses and Dissertations

A model of lens-shaped anticyclonic eddies based on nonlinear shallow water equations is developed. The model is a three-layer fluid and allows for one asymmetric mode as well as specified environmental flows. The solution scheme is a polynomial expansion of the field variables. When inserted into the hydrographic equations, the expansion yields eight first-order differential equations for the time dependent amplitudes. This system of ordinary differential equations is numerically tractable. As long as the initial values meet the requirement of elliptical structure and the prescribed external force is tolerable for the initial values, the numerical solutions are stable. Numerical solutions …

The Growth And Bioenergetics Of Callinectes Sapidus Larvae And The Effects Of Diet Quality On Larval Physiology, James J. Pletl

OES Theses and Dissertations

Food quality, especially ω3 polyunsaturated fatty acids (PUFA), can affect the physiology and metabolic efficiency of larvae of the blue crab, Callinectes sapidus. These affects may correlate with success in development and juvenile recruitment.

Larvae were exposed to two diets differing quantitatively in ω3 PUFA and respiration, excretion, growth, and feeding rates were measured for each larval stage and the megalopal stage. The energy partitioned to molts and specific dynamic action was also measured. T

he ω3 PUFA enriched diet resulted in a lower respiration rate when compared to the unsupplemented diet, but there was little differences in excretion …

Relation Of Groundwater Fluoride Concentrations To Sediment Mineralogy, Potomac Formation (Cretaceous), Southeastern Virginia, Paul Anthony Maciuika

OES Theses and Dissertations

Thirty-seven Early cretaceous sediment samples of the Potomac Formation were obtained from four cores to determine if fluoride bearing minerals are responsible for elevated fluoride concentrations in Potomac Formation groundwaters of southeastern Virginia. Investigative methods included total sediment fluoride and particle size analysis, semiquantitative mineralogical analysis (achieved by X-Ray Diffraction) and statistical methods (cluster, canonical and regression analysis). The sediments showed wide variation in textures, ranging from clean sands and gravels to silty clays. Sediment mineralogies were dependent on the prevailing size fraction, with quartz and feldspar dominating the sand and silt fractions, muscovite primarily being found in the silt …

Biodegradation Of Crude Oil By Marine Higher Fungi, Brian J. Dyer

Biological Sciences Theses & Dissertations

Four experiments were performed to determine the ability of marine higher fungi to grow in and degrade crude oil. Eight species, previously determined to be hydrocarbonoclastic, were grown in artificial sea water medium (ASM) and southern Louisiana crude oil. The dry mycelial weights were measured and consumption of crude oil was measured gravimetrically. The two species with the best growth, Corollospora maritima and Zalerion maritimum, were grown in ASM containing crude oil spiked with three known hydrocarbons. To this was added glucose (0.15%) and incubated 49 days to test for possible cometabolism of hydrocarbons. Hydrocarbons remaining in the growth …

Factors Affecting The Kinetics Of Light Intensity Adaptation In Marine Phytoplankton, Chunzhi Guo

OES Theses and Dissertations

It has been suggested that the recent light history of phytoplankton and the kinetics of photoadaptation can be used to provide information about the vertical mixing processes in the upper mixed layer. To be useful as a parameter in a model of photoadaptation and vertical mixing, the response of a photoadaptive variable to changes in growth irradiance must be monotonic, significant, and comparable in time rate scale to mixing processes. Previous studies of photoadaptation kinetics have focused on the response of phytoplankton to changes in light intensity under continuous illumination. This dissertation attempts to elucidate the effects of light:dark cycle, …

A Numerical Study Of The Variability And The Separation Of The Gulf Stream, Induced By Surface Atmospheric Forcing And Lateral Boundary Flows, Tal Ezer, George L. Mellor

CCPO Publications

A primitive equation model is used to study the effects of surface and lateral forcing on the variability and the climatology of the Gulf Stream system. The model is an eddy-resolving, coastal ocean model that includes thermohaline dynamics and a second-order turbulence closure scheme to provide vertical mixing. The surface forcing consists of wind stress and heat fluxes obtained from the Comprehensive Ocean-Atmosphere Data Set (COADS). Sensitivity studies are performed by driving the model with different forcing (e.g., annual versus zero surface forcing or monthly versus annual forcing). The model climatology, obtained from a five-year simulation of each case, is …

Effects Of Wind, Density, And Bathymetry On A One-Layer Southern Ocean Model, John M. Klinck

CCPO Publications

Steady solutions from a one-layer, wind-driven, primitive equation model are analyzed to determine the importance of wind forcing, pressure gradient force due to the climatological density distribution and bottom form drag on circulation in the Southern Ocean. Five simulations are discussed: three wind-forced simulations, with differing bathymetry (flat bottom, 15% bathymetry, and full bathymetry), one case with full bathymetry forced with the density-induced pressure force, and one case with full bathymetry forced by both wind and density-induced pressure gradients. The simulations presented here confirm the previous speculation (Munk and Palmen, 1951) that form drag is effective in balancing the driving …

The Morphology Of Convex Polygons, Stephan Olariu

Computer Science Faculty Publications

A simple polygon P is said to be unimodal if for every vertex of P, the Euclidian distance function to the other vertices of P is unimodal. The study of unimodal polygons has emerged as a fruitful area of computational and discrete geometry. We study unimodality properties of a number of special convex polygons from the morphological point of view. In particular, we establish a hierarchy among three classes of convex polygons in terms of their unimodality properties.

A Tree Representation For P4-Sparse Graphs, B. Jamison, Stephan Olariu

Computer Science Faculty Publications

A graph G is P₄-sparse if no set of five vertices in G induces more than one chordless path of length three. P₄-sparse graphs generalize both the class of cographs and the class of P₄-reducible graphs. We give several characterizations for P₄-sparse graphs and show that they can be constructed from single-vertex graphs by a finite sequence of operations. Our characterization implies that the P₄-sparse graphs admit a tree representation unique up to isomorphism. Furthermore, this tree representation can be obtained in polynomial time.

A Charming Class Of Perfectly Orderable Graphs, Chinh T. Hoang, Frederic Maffray, Stephan Olariu, Myriam Preissmann

Computer Science Faculty Publications

We investigate the following conjecture of Vašek Chvátal: any weakly triangulated graph containing no induced path on five vertices is perfectly orderable. In the process we define a new polynomially recognizable class of perfectly orderable graphs called charming. We show that every weakly triangulated graph not containing as an induced subgraph a path on five vertices or the complement of a path on six vertices is charming.

Self-Consistent Determination Of Low-Za Pellet Ablation And Pellet Penetration, Linda L. Vahala, Glenn Gerdin, A. G. El Cashlan, Paul Parks

Electrical & Computer Engineering Faculty Publications

The ablation dynamics of LiT pellets are solved self-consistently over a modest range of parameters using a surface dissociation model. The self-consistently determined parameters are then used to modify the standard low-Z pellet penetration codes. Since LiT pellets have certain advantages over carbon [in particular, Li conditioning of the walls and T for refueling a D-T reaction], the penetration of LiT into fusion plasmas is considered.

Temperature And Suction Effects On The Instability Of An Infinite Swept Attachment Line, D. G. Lasseigne, T. L. Jackson, F. Q. Hu

Mathematics & Statistics Faculty Publications

It is known that the incompressible, infinite swept attachment line flow is unstable to streamwise disturbances that originate in the boundary layer when the cross-flow exceeds a critical magnitude. Furthermore, a small degree of suction at the surface has a significant stabilizing influence while a small degree of blowing has a considerable destabilizing influence. This paper investigates the stabilizing and destabilizing effects of, respectively, cooling or heating the plate and the competing or enhancing effects of suction or blowing. A nonorthogonal flow with respect to the attachment line is also considered by adding a component of shear to the mean …