Physical Sciences and Mathematics Commons^™

Virginia Seafood Sustainability, Samantha E. Askin, Robert A. Fisher

Reports

Virginia’s commercial fisheries operate sustainability under a suite of management tools based upon information received from marine scientists and fishery managers who regularly conduct biological sampling of fish while tracking commercial landings and other gathering of required information. Analyses of fishing effort and overall stock conditions, as well as formulas designed to calculate threshold limits for maintaining sustainable stocks are regularly performed. Restrictions on seasons, size, days at sea, and gear are imposed as needed to achieve management supporting long-term biological sustainability.

Leveraging The Interdependencies Between Barrier Islands And Backbarrier Saltmarshes To Enhance Resilience To Sea-Level Rise, Christopher J. Hein, Michael S. Fenster, Keryn B. Gedan, Jeff R. Tabar, Emily A. Hein, Todd Demunda

VIMS Articles

Barrier islands and their backbarrier saltmarshes have a reciprocal relationship: aeolian and storm processes transport sediment from the beaches and dunes to create and build marshes along the landward fringe of the island. In turn, these marshes exert a stabilizing influence on the barrier by widening the barrier system and forming a platform onto which the island migrates, consequently slowing landward barrier migration and inhibiting storm breaching. Here, we present a novel framework for applying these natural interdependencies to managing coastal systems and enhancing barrier-island resilience. Further, we detail application of these principles through a case study of the design …

Winter Harbor Dredge Channel Data Report, Donna A. Milligan, C. Scott Hardaway Jr., Christine A. Wilcox, Cameron Green

Reports

Winter Harbor is a tidal creek that flows between a sandy barrier system and an eroding marsh shoreline. It is an important waterway that provides access to the Chesapeake Bay from the Winter Harbor watershed. In the past, Winter Harbor Inlet was the only hydraulic connection from the Winter Harbor watershed and Chesapeake Bay. The two open water areas of Winter Harbor were separated by marsh channels that hydraulically connected to the mouth at the present-day Winter Harbor Inlet. The federally-defined channel at Winter Harbor was authorized by Congress in 1950. It was authorized as a 12 feet (ft) deep, …

Cedarbush Creek Dredge Channel Data Report, Donna A. Milligan, C. Scott Hardaway Jr., Christine A. Wilcox, Cameron Green

Reports

Cedarbush Creek is located in Gloucester County, Virginia. It is a long, but narrow creek that empties into the York River. The mouth is a wide embayment, but farther north, the creek narrows to about 400 feet wide and extends for about 1.5 miles to its marshy headwaters. Cedarbush Creek has never been dredged, but due to shoaling within the creek, it needs dredging to accommodate vessel traffic. Oliver’s Landing, located near the mouth of Cedarbush Creek, is a working waterfront that supports commercial and recreational boaters in Gloucester. (...)

Data Collection At Fifteen Selected Creeks In Support Of Shallow Water Dredging On Virginia’S Middle Peninsula - Methods & Data Report, Nicholas J. Dinapoli, Donna A. Milligan, C. Scott Hardaway Jr., Christine A. Wilcox, Cameron Green, Scott Lerberg, Eduardo J. Miles, Alex Demeo, George Brooks

Reports

Federal funding has been historically available for the Army Corps of Engineers for shallow draft navigation projects. However, past and recent subsidies have not provided ample funding at levels to sustain maintenance dredging for the 17 federal navigation channels on the Middle Peninsula. Further, funding for maintenance of non-federal channels has been historically neglected by the Commonwealth of Virginia until the Virginia General Assembly established the Virginia Waterway Maintenance Fund in 2018. For the past decade the Middle Peninsula Chesapeake Bay Public Access Authority, the Middle Peninsula Planning District Commission and its member jurisdictions, and the Virginia Institute of Marine …

Parrotts Creek Dredge Channel Data Report, Donna A. Milligan, C. Scott Hardaway Jr., Christine A. Wilcox, Cameron W. Green

Reports

Parrotts Creek is located along the Rappahannock River in Middlesex County, VA. The mouth of the creek is about 850 ft wide, but just inside the mouth of the creek, a spit extends from the upland narrowing the creek to about 300 ft before it widens again. Overall, this is a relatively short, undeveloped creek. Most of the development (wharfs, ramps, piers) occur near the mouth. Most of the more inland areas of the creek are surrounded by woodland. The federally-authorized channel was established in 1955 due to the presence of a public ramp and landing area, as well as …

Living Shoreline Design Guidelines For Shore Protection In Virginia’S Estuarine Environment, C. Scott Hardaway Jr., Donna A. Milligan, Karen Duhring

Reports

The Chesapeake Bay has about 6.5 million people living in its coastal counties and much of the shoreline is privately-owned. For communities along the shore, the continual shore retreat may be a problem. When land along the shore show signs of erosion, property owners tend to address it.

These guidelines are meant to address the need to educate consultants, contractors, and other professionals in the use of living shoreline strategies. It provides the necessary information to determine where they are appropriate and what is involved in their design and construction. The guidelines focus on the use of created marsh fringes …

Effects Of Tidal Flooding On Estuarine Biogeochemistry: Quantifying Flood-Driven Nitrogen Inputs In An Urban, Lower Chesapeake Bay Sub-Tributary, Alfonso Macías-Tapia, Margaret R. Mulholland, Corday R. Selden, Jon Derek Loftis, Peter W. Bernhardt

VIMS Articles

Sea level rise has increased the frequency of tidal flooding even without accompanying precipitation in many coastal areas worldwide. As the tide rises, inundates the landscape, and then recedes, it can transport organic and inorganic matter between terrestrial systems and adjacent aquatic environments. However, the chemical and biological effects of tidal flooding on urban estuarine systems remain poorly constrained. Here, we provide the first extensive quantification of floodwater nutrient concentrations during a tidal flooding event and estimate the nitrogen (N) loading to the Lafayette River, an urban tidal sub-tributary of the lower Chesapeake Bay (USA). To enable the scale of …

Membrane Inlet Mass Spectrometry Method (Reox/Mims) To Measure 15n-Nitrate In Isotope-Enrichment Experiments, Xianbiao Lin, Kaijun Lu, Amber K. Hardison, Et Al

VIMS Articles

Using ¹⁵N stable isotope as a tracer to quantify N transformation rates in isotope-enrichment experiments improves understanding of the N cycle in various ecosystems. However, measuring ¹⁵N-nitrate (¹⁵NO₃⁻) in small volumes of water for these experiments is a major challenge due to the inconvenience of preparing samples by traditional techniques. We developed a “REOX/MIMS” method by applying membrane inlet mass spectrometry (MIMS) to determining ¹⁵NO₃⁻ concentrations in a small volumes of water from isotope-enrichment experiments after converting the dissolved inorganic N to N₂. The nitrates (NO₃^{− …}

Evaluating Epoxy Cure And Adhesion Strength Through Single-Sided Nmr Measurements Of Molecular Mobility, Kayla Copeman

Dissertations, Theses, and Masters Projects

Commonly used in aerospace, automotive, marine, defense, electronic, and manufacturing industries, epoxy adhesives offer advantages over mechanical joints by providing stronger and/or more flexible bonds, more uniform stress distribution, low shrinkage, and lightweight connections between materials. Determination of curing kinetics and properties of interfaces between epoxy and inorganic substrates provides insight that is useful for quality control and defect detection for such applications. Single-sided NMR provides a nondestructive and inexpensive method for probing epoxy materials and spatially resolving the decay of spin-lattice and spin-spin relaxation times (T1 and T2) during and after curing of epoxy resins onto substrates. In this …

Data-Driven Reflectance Estimation Under Natural Lighting, Victoria Cooper

Dissertations, Theses, and Masters Projects

Bidirectional Reflectance Distribution Functions, (BRDFs), describe how light is reflected off of a material. BRDFs are captured so that the materials can be re-lit under new while maintaining accuracy. BRDF models can approximate the reflectance of a material, but are unable to accurately represent the full BRDF of the material. Acquisition setups for BRDFs trade accuracy for speed with the most accurate methods, gonioreflectometers, being the slowest. Image-based BRDF acquisition approaches range from using complicated controlled lighting setups to uncontrolled known lighting to assuming the lighting is unknown. We propose a data-driven method for recovering BRDFs under known, but uncontrolled …

Impact Of Canyon Upwelling And Downwelling In The Mid-Atlantic Bight, Haixing Wang

Dissertations, Theses, and Masters Projects

Submarine canyons can impact regional oceanography and provide a conduit for shelf-slope exchanges via topographically induced processes such as canyon upwelling and downwelling. Between Virginia and New York in the Mid-Atlantic Bight (MAB), there are five major shelf-incising canyons (Norfolk, Washington, Baltimore, Wilmington, and Hudson canyons) and four sizable slope-confined canyons (Accomac, Spencer, Lindenkhol, and Toms canyons). Canyon upwelling and downwelling at these canyons have not been well studied. Consequently, the associated hydrographic variability and dynamics inside the canyons and on the adjacent shelf are largely unknown, and the integrated impact of submarine canyons on MAB shelf hydrography and shelf-slope …

Living Shoreline Sea-Level Resiliency: Performance And Adaptive Management Of Existing Sites Year 3 Summary Report, Donna A. Milligan, C. Scott Hardaway Jr., Christine A. Wilcox, Nick J. Dinapoli

Reports

The focus of this study was to research the resiliency of rock/sand/plant living shoreline protection systems. These systems have been used in Chesapeake Bay for 40 years to reduce erosion, protect infrastructure, and create habitat that is disappearing from the shoreline as sea level rises. The goal was to determine how they have been affected by storm surge and associated wind-driven waves, sea-level rise. This data informed adaptive management strategies to create site-specific morphologically-resilient projects.

The objectives of this 3-year project is monitoring the effectiveness of nature-based resilience projects over time such as those that use hybrid living shoreline management …

Measurement Of The Beam-Normal Single-Spin Asymmetry For Elastic Electron Scattering From ^12c And ^27al, D. Androic, David S. Armstrong, Et Al.

Arts & Sciences Articles

We report measurements of the parity-conserving beam-normal single-spin elastic scattering asymmetries Bn on 12C and 27Al, obtained with an electron beam polarized transverse to its momentum direction. These measurements add an additional kinematic point to a series of previous measurements of Bn on 12C and provide a first measurement on 27Al. The experiment utilized the Qweak apparatus at Jefferson Lab with a beam energy of 1.158 GeV. The average laboratory scattering angle for both targets was 7.7∘, and the average Q2 for both targets was 0.024 37 GeV2 (Q=0.1561 GeV). The asymmetries are Bn=−10.68±0.90(stat)±0.57(syst) ppm for 12C and Bn=−12.16±0.58(stat)±0.62(syst) ppm …

Predicting Road Quality Using High Resolution Satellite Imagery: A Transfer Learning Approach, Ethan Brewer, Jason Lin, Peter Kemper, John Hennin, Daniel Runfola

Arts & Sciences Articles

Recognizing the importance of road infrastructure to promote human health and economic development, actors around the globe are regularly investing in both new roads and road improvements. However, in many contexts there is a sparsity—or complete lack—of accurate information regarding existing road infrastructure, challenging the effective identification of where investments should be made. Previous literature has focused on overcoming this gap through the use of satellite imagery to detect and map roads. In this piece, we extend this literature by leveraging satellite imagery to estimate road quality and concomitant information about travel speed. We adopt a transfer learning approach in …

Performance Optimization With An Integrated View Of Compiler And Application Knowledge, Ruiqin Tian

Dissertations, Theses, and Masters Projects

Compiler optimization is a long-standing research field that enhances program performance with a set of rigorous code analyses and transformations. Traditional compiler optimization focuses on general programs or program structures without considering too much high-level application operations or data structure knowledge. In this thesis, we claim that an integrated view of the application and compiler is helpful to further improve program performance. Particularly, we study integrated optimization opportunities for three kinds of applications: irregular tree-based query processing systems such as B+ tree, security enhancement such as buffer overflow protection, and tensor/matrix-based linear algebra computation. The performance of B+ tree query …

Ultrafast Optical Control And Characterization Of Carrier And Spin Dynamics In Novel Magnetic Topological Insulator Systems, Peiwen Liu

Dissertations, Theses, and Masters Projects

Magnetic topological insulators (MTIs) are of considerable interest in developing novel spintronics and quantum computing applications. Under the topological protection by time-reversal Z2 invariant number, magnetic topological insulators are provided with robust electronic and magnetic properties against local perturbations. The quantum anomalous Hall effect (QAHE), which harbors dissipationless chiral edge states in MTIs, provides a competitive platform for future low-power consumption and high-speed spintronic devices. Although the present studies on both bulk and surface magnetic properties in MTIs have made significant progress, the in-depth understanding of the exchange couplings and the interaction between the two magnetization sources is far from …

Low-Overhead Techniques For Secure And Reliable Gpu Computing, Gurunath Kadam

Dissertations, Theses, and Masters Projects

In recent years, Graphics Processing Units (GPUs) have become a de facto choice to accelerate the computations in various domains such as machine learning, security, financial and scientific computing. GPUs leverage the inherent data parallelism in the target applications to provide high throughput at superior energy efficiency. Due to the rising usage of GPUs for a large number of applications, they are facing new challenges, especially in the security and reliability domains. From the security side, recently several microarchitectural attacks targeting GPUs have been demonstrated. These attacks leak the secret information stored on GPUs, for example, the parameters of a …

Estuarine Microbiomes And Biogeochemistry: Impacts Of Spatiotemporal Variation, Algal Blooms, And Microplastics, Samantha Grace Fortin

Dissertations, Theses, and Masters Projects

Estuaries are biogeochemical hotspots connecting terrestrial and coastal ecosystems. Anthropogenic disturbances, including increased nitrogen loading and plastic pollution, may have significant impacts on estuarine carbon and nitrogen cycling by altering microbiome structure and functions. The overarching goal of this dissertation was to examine how microbiomes and their associated biogeochemical processes are influenced by natural variation and anthropogenic disturbances in the York River Estuary (YRE). In chapter 2, spatial and temporal variation in benthic microbiomes and the rates of denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were examined to determine biotic and abiotic drivers of nitrogen …

Differential Nitrogen Uptake By Aquatic Communities In A Chesapeake Bay Tributary And In The Coastal Alaskan Arctic, Brianna Stanley

Dissertations, Theses, and Masters Projects

Nitrogen (N) is one of the essential building blocks for all life and is available in the form of dissolved N in aquatic ecosystems. It is important to understand how this N can support primary and secondary production mediated by phytoplankton and bacteria, respectively, as it can affect both microbial loop biogeochemistry and the higher trophic levels of food webs. Nitrogen studies have traditionally focused on dissolved inorganic N (DIN) as a labile N source. Dissolved organic N (DON), while still often considered refractory, has been increasingly recognized as an important N source supporting primary and secondary production. However, the …

Sediment Transport And Trapping On The Ayeyarwady-Martaban Continental Shelf, Matthew Joshua Fair

Dissertations, Theses, and Masters Projects

The Ayeyarwady and Thanlwin Rivers, which primarily drain Myanmar, are together one of the largest point sources of freshwater and sediment to the global ocean. Much of the estimated 600 Mt of river sediment annually carried by the combined Ayeyarwady and Thanlwin River system is delivered to a wide continental shelf in the northern Andaman Sea. Called here the Ayeyarwady-Martaban continental shelf, this area is influenced by strong tides, monsoon conditions, and periodic cyclones; however, the processes that dominate dispersal of fluvial material in the coastal ocean of this system remain poorly understood. The shelf exhibits a dramatic asymmetry of …

Polyaromatic-Terminated Iron Polypyridyl Complexes For The Functionalization Of Carbon Surfaces And Electrocatalytic Hydrogen Generation, Caroline Marie Margonis

Dissertations, Theses, and Masters Projects

Artificial Photosynthesis (AP) focuses on developing methods for the conversion of solar energy into chemical fuel in the form of H2 and O2. Heterogeneous photocatalytic systems incorporating carbon nanotubes (CNTs) have shown much promise but are currently limited and expensive due to their reliance on noble metals. To that end, this work focuses on the development and synthesis of cheaper naphthalene- and pyrene-terminated iron polypyridyl complexes for use in the simultaneous functionalization of carbon surfaces, electrocatalytic proton reduction, and eventual incorporation in photocatalytic systems. Cyclic voltammetry was used to characterize the adsorption behavior of each complex on the surface of …

Water Clarity And Suspended Particle Dynamics In The Chesapeake Bay: Local Effects Of Oyster Aquaculture, Regional Effects Of Reduced Shoreline Erosion, And Long-Term Trends In Remotely Sensed Reflectance, Jessica Turner

Dissertations, Theses, and Masters Projects

Water clarity is a key indicator of the ecosystem health in the Chesapeake Bay. Estuarine water clarity fluctuates due to external inputs from the watershed as well as processes occurring within the estuary itself, such as sediment resuspension and organic matter production. Therefore, water clarity requires study at multiple spatial and temporal scales and with multiple metrics. One local-scale process potentially influencing water clarity is shellfish aquaculture. One part of this dissertation examined how water quality and hydrodynamics varied among oyster farms as well as inside versus outside the extent of caged areas located in southern Chesapeake Bay. Current speed …

Light Regulation Of Phytoplankton Growth In San Francisco Bay Studied Using A 3d Sediment Transport Model, Zhengui Wang, Fei Chai, (...), Yinglong J. Zhang, Et Al

VIMS Articles

In San Francisco Bay (SFB), light availability is largely determined by the concentration of suspended particulate matter (SPM) in the water column. SPM exhibits substantial variation with time, depth, and location. To study how SPM influences light and phytoplankton growth, we coupled a sediment transport model with a hydrodynamic model and a biogeochemical model. The coupled models were used to simulate conditions for the year of 2011 with a focus on northern SFB. For comparison, two simulations were conducted with ecosystem processes driven by SPM concentrations supplied by the sediment transport model and by applying a constant SPM concentration of …

Nonlinearity Of Subtidal Estuarine Circulation In The Pearl River Estuary, China, Hongzhou Xu, Jian Shen, Dongxiao Wang, Lin Luo, Bo Hong

VIMS Articles

The Pearl River Estuary (PRE) is a bell-shaped estuary with a narrow deep channel and wide shoals. This unique topographic feature leads to different dynamics of the subtidal estuarine circulation (SEC) in the PRE compared with a narrow and straight estuary. In this study, the nonlinear dynamics of the SEC in the PRE under mean circumstance are analyzed by using a validated 3D numerical model. Model results show that the nonlinear advections reach leading order in the along-channel momentum balance. Modulated by tide, the nonlinear advections show significant temporal variations as they have much larger values during spring tide than …

Extent And Causes Of Chesapeake Bay Warming, Kyle E. Hinson, Marjorie A.M. Friedrichs, Pierre St-Laurent, Fei Da, Raymond G. Najjar

VIMS Articles

Coastal environments such as the Chesapeake Bay have long been impacted by eutrophication stressors resulting from human activities, and these impacts are now being compounded by global warming trends. However, there are few studies documenting long-term estuarine temperature change and the relative contributions of rivers, the atmosphere, and the ocean. In this study, Chesapeake Bay warming, since 1985, is quantified using a combination of cruise observations and model outputs, and the relative contributions to that warming are estimated via numerical sensitivity experiments with a watershed–estuarine modeling system. Throughout the Bay’s main stem, similar warming rates are found at the surface …

Riverine Carbon Cycling Over The Past Century In The Mid-Atlantic Region Of The United States, Yuanzi Yao, Hanqin Tian, Shufen Pan, Raymond G. Najjar, Marjorie A.M. Friedrichs, Et Al

VIMS Articles

Rivers are an important component of the terrestrial-aquatic ocean continuum as they serve as a conduit for transporting carbon from the land to the coastal ocean. It is essential to track the fate of this carbon, including how much carbon is buried in the riverbed, outgassed to the atmosphere, and exported to the ocean. However, it is often difficult to quantify these carbon transport processes on the watershed scale because observational data obtained by field surveys can only be used to estimate the magnitude of these processes at distinct points. In this study, we used a coupled terrestrial-aquatic ecosystem model …

Molecular Cluster Fragment Machine Learning Training Techniques To Predict Energetics Of Brown Carbon Aerosol Clusters, Emily E. Chappie

Undergraduate Honors Theses

Density functional theory (DFT) has become a popular method for computational work involving larger molecular systems as it provides accuracy that rivals ab initio methods while lowering computational cost. Nevertheless, computational cost is still high for systems greater than ten atoms in size, preventing their application in modeling realistic atmospheric systems at the molecular level. Machine learning techniques, however, show promise as cost-effective tools in predicting chemical properties when properly trained. In the interest of furthering chemical machine learning in the field of atmospheric science, I have developed a training method for predicting cluster energetics of newly characterized nitrogen-based brown …

Areas Suitable For Living Shorelines: Ranked For Co-Benefits Provided, Pamela Mason, Tamia Rudnicky, Jessica Hendricks, Marcia Berman

Data

The Center for Coastal Resources Management (CCRM) at the Virginia Institute of Marine Science (VIMS) has been developing tools to guide local governments in shoreline management. Using a number of criteria, the Shoreline Management Model (SMM) determines appropriate shoreline best management practices. This layer contains only those areas determined to be suitable for non-structural plant marsh or plant marsh with sill recommendations. These areas are prioritized using a scoring method that considers nutrient removal potential, benefits provided to coastal buildings, the potential for the project to provide habitat continuity and enhancement, and the potential the project to add resilience for …

Impacts Of Multiple Environmental Changes On Long- Term Nitrogen Loading From The Chesapeake Bay Watershed, Shufen Pan, Zihao Bian, (...), Marjorie A.M. Friedrichs, Et Al

VIMS Articles

Excessive nitrogen can enter estuarine and coastal areas from land, disturbing coastal ecosystems and causing serious environmental problems. The Chesapeake Bay is one of the regions that have experienced hypoxia and harmful algal blooms in recent decades. This study estimated nitrogen export from the Chesapeake Bay watershed (CBW) to the estuary from 1900 to 2015 by applying a state-of-the-art numerical model. Nitrogen loading from the CBW continually increased from the 1900s to the 1990s and has declined since then. The key contributors to nitrogen export have shifted from atmospheric nitrogen deposition (before the 1960s) to synthetic nitrogen fertilizer (after the …