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Articles 1 - 30 of 45
Full-Text Articles in Physical Sciences and Mathematics
Classification Of Non-Heat Generating Outdoor Objects In Thermal Scenes For Autonomous Robots, William L. Fehlman
Classification Of Non-Heat Generating Outdoor Objects In Thermal Scenes For Autonomous Robots, William L. Fehlman
Dissertations, Theses, and Masters Projects
We have designed and implemented a physics-based adaptive Bayesian pattern classification model that uses a passive thermal infrared imaging system to automatically characterize non-heat generating objects in unstructured outdoor environments for mobile robots. In the context of this research, non-heat generating objects are defined as objects that are not a source for their own emission of thermal energy, and so exclude people, animals, vehicles, etc. The resulting classification model complements an autonomous bot's situational awareness by providing the ability to classify smaller structures commonly found in the immediate operational environment. Since GPS depends on the availability of satellites and onboard …
The Survival Benefit Of Benthic Macroalgae Gracilaria Vermiculophylla As An Alternative Nursery Habitat For Juvenile Blue Crabs, Justin A. Falls
The Survival Benefit Of Benthic Macroalgae Gracilaria Vermiculophylla As An Alternative Nursery Habitat For Juvenile Blue Crabs, Justin A. Falls
Dissertations, Theses, and Masters Projects
The Chesapeake Bay blue crab is in decline. One of the threats to it is the loss of its once plentiful nursery habitat, seagrass, due to baywide eutrophication and climate change. The emergence of the non-native benthic macroalga Gracilaria vermiculophylla may offer the blue crab an alternative nursery if it can provide juvenile crabs a refuge from predation. The ability of Gracilaria to protect juvenile blue crabs was investigated in mesocosm and field survival studies, which were combined into a larger dataset. All of these studies used tethering and therefore a tethering validation study in mesocosms accompanied these experiments. In …
Sediment Transport And Erodibility In The York River Estuary: A Model Study, Jeffrey Paul Rinehimer
Sediment Transport And Erodibility In The York River Estuary: A Model Study, Jeffrey Paul Rinehimer
Dissertations, Theses, and Masters Projects
A cohesive sediment bed model was implemented in the Community Sediment Transport Modeling System (CSTMS) to examine processes influencing sediment erodibility and suspended sediment concentrations. Estimates of eroded mass from the sediment bed model were calibrated and verified with erosion chamber measurements from the York River, Virginia, a tidally-dominated environment. A constant erosion rate parameter combined with depth-varying critical shear stress was sufficient to model erosion observations of depth-limited sediment cores. Sensitivity of total eroded mass to seasonal variations in erodibility and changes in consolidation time scale was evaluated during spring-neap variations in bottom stresses. Differences were greatest during spring …
Interspecific Interactions In Oyster Reef Communities: The Effect Of Established Fauna On Oyster Larval Recruitment, Brian B. Barnes
Interspecific Interactions In Oyster Reef Communities: The Effect Of Established Fauna On Oyster Larval Recruitment, Brian B. Barnes
Dissertations, Theses, and Masters Projects
The behaviors of oyster larvae are difficult to monitor or experimentally manipulate, especially in field conditions. As a result, little is known of the fate of oysters in the larval portion of their life cycle, prior to recruitment. At the transition from pelagic larvae to benthic adults, larvae are likely to come into contact with many invertebrates resident on oyster reefs. Of these, fouling epifauna are generally believed to reduce the settlement of interspecific larvae through competitive exclusion and predation. Studies of these interactions, however, often utilize artificial settlement panels, which can exhibit different recruitment patterns to those observed on …
Idiopathic Lesions And Visual Deficits In The American Lobster (Homarus Americanus) From Longs Island Sound, Ny, Christopher Robert Magel
Idiopathic Lesions And Visual Deficits In The American Lobster (Homarus Americanus) From Longs Island Sound, Ny, Christopher Robert Magel
Dissertations, Theses, and Masters Projects
In 1999 a mass mortality of the American lobster (Homarus americanus) occurred in western Long Island Sound (WLIS). Although the etiology remains unknown, warm bottom water temperature, hypoxia, heavy metal poisoning, and pesticides have been suggested as casual factors. Subsequently, lobsters from WLIS have continued to display symptoms of morbidity that include lethargy and cloudy grey eyes, caused by idiopathic lesions. The effects of these lesions on lobster vision are unknown. We therefore used electoretinography (ERG) to document changes in visual function in lobsters obtained from WLIS, while simultaneously using histology to quantify the extent of damage. Of the lobsters …
A Molecular Analysis Of Atlantic Menhaden (Brevoortia Tyrannus) Stock Structure, Abigail J. Lynch
A Molecular Analysis Of Atlantic Menhaden (Brevoortia Tyrannus) Stock Structure, Abigail J. Lynch
Dissertations, Theses, and Masters Projects
Atlantic menhaden is an ecologically and economically important species along the U.S. east coast. As a filter-feeder and key prey fish, it provides a critical link between primary production, phytoplankton, and larger piscivorous predators, such as striped bass, bluefish, and weakfish. The species is also the target of one of the largest commercial fisheries in the country. Menhaden are assessed as a single, coastwide stock, and recent assessments indicate that it is not overfished. However, there is very limited population genetics data to support the assumption of a single stock. Additionally, the recent consolidation of the fishery and localization of …
Effects Of Shoreline Development And Oyster Reefs On Benthic Communities In Lynnhaven, Virginia, Amanda Sue Lawless
Effects Of Shoreline Development And Oyster Reefs On Benthic Communities In Lynnhaven, Virginia, Amanda Sue Lawless
Dissertations, Theses, and Masters Projects
Shoreline hardening and construction of restoration oyster reefs are occurring at rapid rates throughout Chesapeake Bay and little research has been conducted to determine whether installment of a hardened shoreline and oyster reef placement has an effect on the surrounding benthic infaunal communities. I investigated the effects of shoreline development and oyster reefs on benthic communities in Lynnhaven, Virginia. Throughout Lynnhaven, I determined the effects of shoreline type (natural marsh, oyster reef, rip-rap and bulkhead), sediment grain size, Total Organic Carbon/Total Nitrogen (TOC/TN) of the sediment, and predation (caging study) on density, biomass, and diversity of benthic infauna. An information-theoretic …
Zooplankton Community Structure In A Cyclonic And Mode-Water Eddy In The Sargasso Sea, Bethany Rose Eden
Zooplankton Community Structure In A Cyclonic And Mode-Water Eddy In The Sargasso Sea, Bethany Rose Eden
Dissertations, Theses, and Masters Projects
Recent evidence suggests that mesoscale eddies are an important mechanism for supplying nutrients to the surface waters of oligotrophic gyres. However, little is known about the biological response to these physical perturbations. Because mesozooplankton play a key role in food-web interactions and the flux of carbon and other elements from surface waters, changes in mesozooplankton community structure can affect biogeochemical cycling. During the summers of 2004 and 2005, respectively, we followed the development of a cyclonic eddy and an anti-cyclonic mode-water eddy in the Sargasso Sea. Zooplankton tows were conducted across both eddies using a Multiple Opening and Closing Net …
Modeling Mercury Biomagnification In The South River, Kyle R. Tom
Modeling Mercury Biomagnification In The South River, Kyle R. Tom
Dissertations, Theses, and Masters Projects
No abstract provided.
Twine-Top Modifications Of Sea-Scallop Dredges: Reducing Yellowtail-Flounder Bycatch, Kelli A. Milleville
Twine-Top Modifications Of Sea-Scallop Dredges: Reducing Yellowtail-Flounder Bycatch, Kelli A. Milleville
Dissertations, Theses, and Masters Projects
No abstract provided.
Novel Use Of A Natural Isotope Signature To Track Recruitment And Evaluate Age Determination Methods For The 2002 Year Class Of American Shad In The York River, Sally A. Upton
Dissertations, Theses, and Masters Projects
No abstract provided.
Recent Sedimentation Patterns And Facies Distribution On The Waipaoa River Shelf, N.Z, Lila Eve Rose
Recent Sedimentation Patterns And Facies Distribution On The Waipaoa River Shelf, N.Z, Lila Eve Rose
Dissertations, Theses, and Masters Projects
No abstract provided.
An Evaluation Of Norovirus Persistence In Estuarine Water And Of Methods For Its Detection In Treated Sewage Effluent, Margaret H. Fagan
An Evaluation Of Norovirus Persistence In Estuarine Water And Of Methods For Its Detection In Treated Sewage Effluent, Margaret H. Fagan
Dissertations, Theses, and Masters Projects
No abstract provided.
A Modern Sediment Budget For The Continental Shelf Off The Waipaoa River, New Zealand, Andrea J. Miller
A Modern Sediment Budget For The Continental Shelf Off The Waipaoa River, New Zealand, Andrea J. Miller
Dissertations, Theses, and Masters Projects
No abstract provided.
Controls On Continental Shelf Stratigraphy: Waiapu River, New Zealand, Heidi M. Wadman
Controls On Continental Shelf Stratigraphy: Waiapu River, New Zealand, Heidi M. Wadman
Dissertations, Theses, and Masters Projects
A quantitative understanding of the processes controlling sediment transport and deposition across the land/sea interface is crucial to linking terrestrial and marine environments and understanding the formation of marine stratigraphy. The nature and distribution of terrestrial-derived sediment preserved in shelf stratigraphy in turn provides insight into the complex linkages inherent in source-to-sink sediment dynamics. Located inboard of an actively subducting plate boundary and characterized by one of the highest sediment yields in the world, the open-shelf setting off of the Waiapu River in New Zealand presents an excellent location to improve our understanding of the factors controlling the formation of …
Mesopelagic Zooplankton Feeding Ecology And Effects On Particle Repackaging And Carbon Transport In The Subtropical And Subarctic North Pacific Ocean, Stephanie E. Wilson
Mesopelagic Zooplankton Feeding Ecology And Effects On Particle Repackaging And Carbon Transport In The Subtropical And Subarctic North Pacific Ocean, Stephanie E. Wilson
Dissertations, Theses, and Masters Projects
Differences in zooplankton community structure and diet within the mesopelagic zone (base of euphotic zone to 1000 m) play a key role in affecting the efficiency by which organic matter is exported to depth, but how the structure of mesopelagic food webs change with depth or location is poorly known. I examined how mesopelagic zooplankton affect particle export in an oligotrophic (Hawaii Ocean Time-series site ALOHA) compared to a mesotrophic (Japanese time series site K2) open-ocean system. In the first part of the study, I investigated how fecal pellet characteristics change with depth in order to quantify the extent of …
Correction Of Finite Size Errors In Many-Body Electronic Structure Calculations, Hendra Kwee
Correction Of Finite Size Errors In Many-Body Electronic Structure Calculations, Hendra Kwee
Dissertations, Theses, and Masters Projects
Electronic structure calculations using simulation cells for extended systems typically incorporate periodic boundary conditions as an attempt to mimic the real system with a practically infinite number of particles. Periodic boundary conditions introduce unphysical constraints that give rise to finite-size errors. In mean-field type calculations, the infinite size limit is achieved by simple quadrature in the Brillouin zone using a finite number of k-points. Many-body electronic structure calculations with explicit two-particle interactions cannot avail themselves of this simplification. Direct extrapolation is computationally costly while size correction with less accurate methods is frequently not sufficiently accurate. The Hartree-Fock method neglects the …
Methods For Stabilizing High Reynolds Number Lattice Boltzmann Simulations, Brian Robert Keating
Methods For Stabilizing High Reynolds Number Lattice Boltzmann Simulations, Brian Robert Keating
Dissertations, Theses, and Masters Projects
The Lattice Boltzmann Method (LBM) is a simple and highly efficient method for computing nearly incompressible fluid flow. However, it is well known to suffer from numerical instabilities for low values of the transport coefficients. This dissertation examines a number of methods for increasing the stability of the LBM over a wide range of parameters. First, we consider a simple transformation that renders the standard LB equation implicit. It is found that the stability is largely unchanged. Next, we consider a stabilization method based on introducing a Lyapunov function which is essentially a discrete-time H-function. The uniqueness of an H-function …
Topics In Mode Conversion Theory And The Group Theoretical Foundations Of Path Integrals, Andrew Stephen Richardson
Topics In Mode Conversion Theory And The Group Theoretical Foundations Of Path Integrals, Andrew Stephen Richardson
Dissertations, Theses, and Masters Projects
This dissertation reports research about the phase space perspective for solving wave problems, with particular emphasis on the phenomenon of mode conversion in multicomponent wave systems, and the mathematics which underlie the phase space perspective. Part I of this dissertation gives a review of the phase space theory of resonant mode conversion. We describe how the WKB approximation is related to geometrical structures in phase space, and how in particular ray-tracing algorithms can be used to construct the WKB solution. We further review how to analyze the phenomena of mode conversion from the phase space perspective. By making an expansion …
As Particles Collide: Extra Dimensions And Heavy Leptons, Erin Kathleen De Pree
As Particles Collide: Extra Dimensions And Heavy Leptons, Erin Kathleen De Pree
Dissertations, Theses, and Masters Projects
Despite excellent agreement with experiment, the Standard Model leaves several issues unresolved. These issues will be explored and several extensions to the Standard Model introduced: models with extra dimensions and a fourth family of particles.;In extra dimensional models, there are Fourier modes of the Standard Model particles. We study the detection of bound states of one of the modes and its Standard Model particle.;We then explore a particular model of extra dimensions known as Randall-Sundrum or warped extra dimensions. We will see how this model affects top quark measurements at the proposed International Linear Collider.;Finally we will study the detection …
Surface Study Of Niobium For Superconducting Radio Frequency (Srf) Accelerators, Hui Tian
Surface Study Of Niobium For Superconducting Radio Frequency (Srf) Accelerators, Hui Tian
Dissertations, Theses, and Masters Projects
Niobium rf superconductivity is a near-surface phenomenon because of the shallow rf penetration depth. Accordingly, the performance of Nb SRF accelerator cavities is strongly impacted by the topmost few nanometers interior surface, especially as impacted by the final surface conditioning treatments.;Surface topography impacts performance through local loss of superconductivit caused by intrusion of the rf magnetic field, which is enhanced at sharp protrusions. "Sharpness" comprises both vertical and lateral aspects, requiring development a new characterization approach beyond the familiar roughness measurements (Ra, Rz), which view only the vertical component. Stylus profilomety and atomic force microscopy traces view surface topography from …
Time-Resolved Magnetic Flux And Ac-Current Distributions In Superconducting Yttrium Barium Copper Oxide Thin Films And Multifilaments, Ran Yang
Dissertations, Theses, and Masters Projects
Time-resolved magneto-optical imaging (TRMOI) technique allows dynamic ac transport measurements on superconductors. The high time and spatial resolutions of the measurements also offer good quantitative data analysis of the MO images. YBa2Cu 3O7-delta (YBCO) was discovered as a high-temperature superconductor (HTSC) which has wide applications due to its high critical temperature of Tc = 91 K, and high critical current density Jc in the order of 106-7 Acm-2. Many of the applications require high ac current load and a high magnetic field. We study the interaction behavior of YBCO thin films in an ac transport current and a dc magnetic …
Measurement Of Inclusive Proton Double -Spin Asymmetries And Polarized Structure Functions, Robert G. Fersch
Measurement Of Inclusive Proton Double -Spin Asymmetries And Polarized Structure Functions, Robert G. Fersch
Dissertations, Theses, and Masters Projects
The scattering of polarized electrons from a polarized proton target provides a means for studying the internal spin structure of the proton. The CLAS (CEBAF Large Acceptance Spectrometer) EG1b experiment in Hall-B at Jefferson Laboratory measured double-spin inclusive and exclusive electron-nucleon scattering asymmetries using longitudinally polarized frozen NH3 and ND3 targets and a longitudinally polarized electron beam at 4 different energies (1.6, 2.5, 4.2, 5.6 GeV). Extraction of the virtual photon asymmetry Ap1 (for 0.05 GeV2 < Q2 < 5.0 GeV2) provides precision measurements of the polarized proton spin-structure function gp1 in and above the resonance region. Linear regression of data between the varying energies yields new constraints on the virtual photon asymmetry Ap2 (and thus the structure function gp2 ) in the resonance region (for 0.3 GeV2 < Q2 < 1.0 GeV2). Measurements of these structure functions and their moments allows testing of perturbative Quantum Chromodynamics (pQCD) models and evaluation of moments of the structure functions in the Operator Product Expansion. Testing of Chiral Perturbation Theory (chiPT) at Q2 < 0.2 GeV 2 is enabled by the new data. Other applications of polarized structure functions include measurement of foward-spin polarizability, evaluation of high-order corrections in 1H hyperfine splitting, and testing of quark-hadron duality.
Community Dynamics In Submersed Aquatic Vegetation: Intermediate Consumers As Mediators Of Environmental Change, James G. Douglass
Community Dynamics In Submersed Aquatic Vegetation: Intermediate Consumers As Mediators Of Environmental Change, James G. Douglass
Dissertations, Theses, and Masters Projects
Natural ecosystems are strongly affected by changes in resource supply (bottom-up forces) and by changes in upper trophic levels (top-down forces). The extent to which these processes impact a system depends largely on the responses of organisms at middle trophic levels. In seagrass beds, a group of mid-level consumers known as mesograzers form a critical link in the chain of impact, connecting seagrass and epiphytic algae with predatory fishes and crustaceans. I observed dramatic seasonal and interannual changes in mesograzer abundance and species composition in eelgrass (Zostera marina) beds of lower Chesapeake Bay, Virginia, and endeavored to explain the top-down …
Acoustic Measurements Of Cohesive Sediment Transport: Suspension To Consolidation, Ho Kyung Ha
Acoustic Measurements Of Cohesive Sediment Transport: Suspension To Consolidation, Ho Kyung Ha
Dissertations, Theses, and Masters Projects
This dissertation aims at utilizing the acoustic approach to measure cohesive sediment behaviors including (1) suspension, (2) settling, (3) deposition and (4) consolidation. The first two processes were attempted to interpret by means of backscattered signal analysis, while the last two processes were done by echo signal analysis. The acoustic instruments used in this study include Acoustic Doppler Velocimeter (ADV), Pulse Coherent Acoustic Doppler Profiler (PC-ADP) and Micro-Chirp system. Used sediments are pure kaolinite and in-situ sediments collected from Mai Po and Clay Bank. 5-MHz ADV was used to estimate the suspended sediment concentration (SSC) and settling velocity (ws). For …
Mercury Levels In Newly Independent Songbirds, Anne Moire Condon
Mercury Levels In Newly Independent Songbirds, Anne Moire Condon
Dissertations, Theses, and Masters Projects
No abstract provided.
Effects Of Metal-Based Montmorillonite Clay And Zeolite Additives On The Fire Retardance And Smoke Suppression Of Poly(Vinyl Chloride), Alexander George Zestos
Effects Of Metal-Based Montmorillonite Clay And Zeolite Additives On The Fire Retardance And Smoke Suppression Of Poly(Vinyl Chloride), Alexander George Zestos
Dissertations, Theses, and Masters Projects
No abstract provided.
Organotitanium-Aluminum Promoted Carbometalations Of Alkynols: Substituent Effects, Nikola A. Nikolic
Organotitanium-Aluminum Promoted Carbometalations Of Alkynols: Substituent Effects, Nikola A. Nikolic
Dissertations, Theses, and Masters Projects
No abstract provided.
Novel Approaches To The Fabrication Of Highly Conductive Silver Surfaces Well Adhered To Polyimide Substrates, Luke Michael Davis
Novel Approaches To The Fabrication Of Highly Conductive Silver Surfaces Well Adhered To Polyimide Substrates, Luke Michael Davis
Dissertations, Theses, and Masters Projects
No abstract provided.
Nearshore Morphology And Lithology: Links To Framework Geology And Shoreline Change, Jennifer L. Miselis
Nearshore Morphology And Lithology: Links To Framework Geology And Shoreline Change, Jennifer L. Miselis
Dissertations, Theses, and Masters Projects
Despite evidence of the geologic and morphologic complexity of inner shelves worldwide, there is a paucity of observations from the nearshore, inhibiting direct comparison of these factors to coastal change. Using geophysical instruments to characterize the geology of the nearshore, this research focuses on the relationships between nearshore stratigraphy, sediment heterogeneity, shoreface morphology and shoreline behavior. While generally not considered in engineering models of shoreline evolution, these factors influence nearshore processes. Overall, the findings presented highlight the importance of nearshore geology, both at the seafloor and underlying it, in contributing to modem sediment transport processes affecting beaches. Shallow, sub-seafloor geology …