Physical Sciences and Mathematics Commons^™

Hydrodynamics And Morphology Of Equilibrium Tidal Freshwater Channels, Carl Friedrichs

Presentations

This presentation addresses the dynamics and morphology of near-equilibrium tidal freshwater channels. The dynamics considered are based on sectionally-averaged current velocity and a barotropic momentum balance. A series of geometries are examined which attempt to encompass generic, reasonably realistic scenarios for tidal fresh water channels found in nature. This work presents and scales the governing equations of mass and momentum conservation. An essential step in this process is the identification of key length scales, corresponding inverse length scales (or "spatial rates of change"), and dimensionless ratios to be used subsequently to determine when and where to keep or neglect various …

2011 Chesapeake Bay Sav Coverage, Sav Data Administrator, Virginia Institute Of Marine Science

Data

Abstract: The 2011 Chesapeake Bay SAV Coverage was mapped from 1:24,000 black and white aerial photography to assess water quality in the Bay. Each area of SAV was interpreted from the rectified photography and classified into one of four density classes by the percentage of cover. The SAV beds were entered into an SDE GIS fetaure class using the quality control procedures documented below. The dataset contains all SAV areas that were identified from the areas flown. Some areas that are presumed to contain no SAV were not flown. Some small beds, particularly along narrow tributaries may not have been …

Evaluating The Capabilities Of The Second Generation Pics Settling Column Floc Camera In A Muddy Tidal Estuary, York River, Virginia, Usa, Grace M. Cartwright, S. Jarrell Smith, Carl T. Friedrichs, Kelsey A. Fall

Presentations

No abstract provided.

Acoustic Scattering To Measure Dispersed Oil Droplet Size And Sediment Particle Size, Paul D. Panetta, Leslie Bland, Grace M. Cartwright, Carl T. Friedrichs

Presentations

No abstract provided.

Dual Use Of A Sediment Mixing Tank For Calibrating Acoustic Backscatter And Direct Doppler Measurement Of Settling Velocity, Grace M. Cartwright, Carl T. Friedrichs, Paul D. Panetta

Presentations

While the Acoustic Doppler Velocimeter (ADV) is designed to determine fluid velocity, it is important to recognize that it is actually the velocity of the scatterers themselves that is measured. Thus in a calibration tank designed to relate sediment-induced backscatter to sediment concentration, the vertical velocity registered by an ADV at a given point is actually the true fluid velocity plus the sediment’s settling velocity. And absent net vertical volume flux, the average vertical velocity registered by an ADV across a horizontal plane is equal to the mean sediment settling velocity. For this study, a series of ADV calibrations were …

How To Create A Two-Component Spinor, Charles G. Torre

How to... in 10 minutes or less

Let (M, g) be a spacetime, i.e., a 4-dimensional manifold M and Lorentz signature metric g. The key ingredients needed for constructing spinor fields on the spacetime are: a complex vector bundle E -> M ; an orthonormal frame on TM ; and a solder form relating sections of E to sections of TM (and tensor products thereof). We show how to create a two-component spinor field on the Schwarzschild spacetime using the DifferentialGeometry package in Maple. PDF and Maple worksheets can be downloaded from the links below.

The Octonions And The Exceptional Lie Algebra G2, Ian M. Anderson

Research Vignettes

The octonions O are an 8-dimensional non-commutative, non-associative normed real algebra. The set of all derivations of O form a real Lie algebra. It is remarkable fact, first proved by E. Cartan in 1908, that the the derivation algebra of O is the compact form of the exceptional Lie algebra G2. In this worksheet we shall verify this result of Cartan and also show that the derivation algebra of the split octonions is the split real form of G2.

PDF and Maple worksheets can be downloaded from the links below.

Higher Order Symmetries Of The Kdv Equation, Ian M. Anderson

Research Vignettes

In this worksheet we symbolically construct the formal inverse of the total derivative operator and use it to construct the recursion operator for the higher-order symmetries of the KdV equation. Using this recursion operator we generate the first 5 generalized symmetries of the KdV equation and verify that they all commute.

PDF and Maple worksheets can be downloaded from the links below.

Molecule For Electronics: A Myriad Of Opportunities Comes With Daunting Challenges, Ranjit Pati

Department of Physics Publications

Since the invention of Integrated Circuit (IC) in 1958, we have seen an unprecedented growth in Si-based electronics industry; ICs are currently used in almost all electronic gadgets. However, it is now very much clear that this era of growth we have been witnessing for the last five decades will soon hit the brick wall, once the transistor size reaches the physical limit of miniaturization.

Relationships Between Erodibility And Fine-Grained Seabed Properties On Tidal To Seasonal Time-Scales, York River Estuary, Virginia, Usa, Lindsey M. Kraatz, Carl T. Friedrichs, Grace M. Cartwright, Kelsey A. Fall

Presentations

No abstract provided.

Controls On Particle Settling Velocity And Bed Erodibility In The Presence Of Muddy Flocs And Pellets As Inferred By Advs, York River Estuary, Virginia, Usa, Kelsey A. Fall, Carl T. Friedrichs, Grace M. Cartwright

Presentations

No abstract provided.

Damping Of Turbulence By Suspended Sediment: Ramifications Of Under-Saturated, Critically-Saturated, And Over-Saturated Conditions, Carl T. Friedrichs

Presentations

No abstract provided.

A Homogeneous Solution Of The Einstein-Maxwell Equations, Charles G. Torre

Research Vignettes

We exhibit and analyze a homogeneous spacetime whose source is a pure radiation electromagnetic field [1]. It was previously believed that this spacetime is the sole example of a homogeneous pure radiation solution of the Einstein equations which admits no electromagnetic field (see [2] and references therein). Here we correct this error in the literature by explicitly displaying the electromagnetic source. This result implies that all homogeneous pure radiation spacetimes satisfy the Einstein-Maxwell equations.

PDF and Maple worksheets can be downloaded from the links below.

Deep Silicate Absorption Features In Compton-Thick Active Galactic Nuclei Predominantly Arise Due To Dust In The Host Galaxy, A. D. Goulding, D. M. Alexander, F. E. Bauer, W. R. Forman, R. C. Hickox

Dartmouth Scholarship

We explore the origin of mid-infrared (mid-IR) dust extinction in all 20 nearby (z < 0.05) bona fide Compton-thick (N _H > 1.5 × 10²⁴ cm^–2) active galactic nuclei (AGNs) with hard energy (E > 10 keV) X-ray spectral measurements. We accurately measure the silicate absorption features at λ ~ 9.7 μm in archival low-resolution (R ~ 57-127) Spitzer Infrared Spectrograph spectroscopy, and show that only a minority (≈45%) of nearby Compton-thick AGNs have strong Si-absorption features (S _9.7 = ln (f _int/f _obs) 0.5) which would indicate significant dust attenuation. The majority (≈60%) are star …

How To Create A Lie Algebra, Ian M. Anderson

How to... in 10 minutes or less

We show how to create a Lie algebra in Maple using three of the most common approaches: matrices, vector fields and structure equations. PDF and Maple worksheets can be downloaded from the links below.

Starcraft Ii In-Game Action Lists, Gong Wei, Ee Peng Lim, Achananuparp Palakorn, Feida Zhu, David Lo, Freddy Chua

SMU Research Data

1732 event logs of actions performed by players in Starcraft II public replays downloaded from GameReplays.org.

The Data Set consists of 1732 log files (Size: 55 MB) compressed into a Zip archive (Size: 9.3 MB).

This dataset has accumulated 267 downloads from 19 July 2012 to 2 Nov 2017 before being transferred to another collection.

Old URL: http://ink.library.smu.edu.sg/data/1/

Delayed Observation Planning In Partially Observable Domains, Pradeep Reddy Varakantham, Janusz Marecki

Research Collection School Of Computing and Information Systems

Traditional models for planning under uncertainty such as Markov Decision Processes (MDPs) or Partially Observable MDPs (POMDPs) assume that the observations about the results of agent actions are instantly available to the agent. In so doing, they are no longer applicable to domains where observations are received with delays caused by temporary unavailability of information (e.g. delayed response of the market to a new product). To that end, we make the following key contributions towards solving Delayed observation POMDPs (D-POMDPs): (i) We first provide an parameterized approximate algorithm for solving D-POMDPs efficiently, with desired accuracy; and (ii) We then propose …

Combining Observational And Numerical Model Results To Improve Estimates Of Hypoxic Volume In Chesapeake Bay, A. J. Bever, Marjorie A.M. Friedrichs, Carl T. Friedrichs, M. E. Scully

Presentations

No abstract provided.

Perturbations In Microtubule Mechanics From Tubulin Preparation, Taviare Hawkins

Physics Faculty Scholarship

Microtubules are essential structures for cellular organization. They support neuronal processes and cilia, they are the scaffolds for the mitotic spindle, and they are the tracks for intracellular transport that actively organizes material and information within the cell. The mechanical properties of microtubules have been studied for almost 30 years, yet the results from different groups are startlingly disparate, ranging over an order of magnitude. Here we present results demonstrating the effects of purification, associated-protein content, age, and fluorescent labeling on the measured persistence length using the freely fluctuating filament method. We find that small percentages (<1%) of residual microtubule-associated proteins left over in the preparation can cause the persistence length to double, and that these proteins also affect the persistence length over time. Interestingly, we find that the fraction of labeled tubulin dimers does not affect the measured persistence length. Further, we have enhanced the analysis method established by previous groups. We have added a bootstrapping with resampling analysis to estimate the error in the variance data used to determine the persistence length. Thus, we are able to perform a weighted fit to the data to more accurately determine the persistence length.

Spatial And Temporal Trends In Tidal Flat Shape In San Francisco Bay, J. A. Bearman, Carl T. Friedrichs, B. E. Jaffe, A. C. Foxgrover

Presentations

No abstract provided.

1112+3548_Nir_Spex, J. Patience

Publications and Research

No abstract provided.

Results Of The Us Ioos Testbed For Comparison Of Hydrodynamic And Dissolved Oxygen Models Of The Chesapeake Bay, M.A.M. Friedrichs, A. J. Bever, M. E. Scully, W. Long

Presentations

Results from multiple 3-D hydrodynamic and dissolved oxygen models for Chesapeake Bay have been compared to each other and to EPA monitoring data for the years 2004 and 2005. On seasonal time-scales, the models all do well in capturing fundamental aspects of the hydrodynamic and oxygen fields, although the intensity of the pycnocline is underestimated. Models with constant net respiration independent of nutrient supply reproduce hypoxia nearly as well as much more complex, nutrient-dependent ecological models. Seasonal variation in DO was insensitive to seasonal cycles in the respiration rate, freshwater input, and density stratification. Rather, seasonal variation in DO was …

Use Of Acoustic Doppler Velocimeters (Advs) To Infer Relationships Among Fine Sediment Settling, Bed Erodibility And Particle Type, York River Estuary, Va, K. A. Fall, Carl T. Friedrichs, Grace M. Cartwright

Presentations

Bed erodibility and particle settling velocity are key factors influencing fine sediment dynamics in coastal and estuarine environments. In order to better constrain inherently complex, temporally-varying relationships among hydrodynamics, bed properties and particle types, near-bed ADVs have been maintained in the York River Estuary since 2006. The ADVs provide measurements of bottom stress, suspended sediment concentration (C, via calibrated backscatter), and particle settling velocity (Ws, via a Rouse balance). By assuming Ws to be the combined result of rapidly settling fecal pellets plus more slowly settling flocs, the time-varying fraction of pellets versus flocs can be estimated. Vertical integration of …

Dual Use Of A Sediment Mixing Tank For Calibrating Acoustic Backscatter And Direct Doppler Measurement Of Settling Velocity, Grace M. Cartwright, Carl T. Friedrichs, P. D. Panetta

Presentations

While the Acoustic Doppler Velocimeter (ADV) is designed to determine fluid velocity, it is important to recognize that it is actually the velocity of the scatterers themselves that is measured. Thus in a calibration tank designed to relate sediment-induced backscatter to sediment concentration, the vertical velocity registered by an ADV at a given point is actually the true fluid velocity plus the sediment’s settling velocity. And absent net vertical volume flux, the average vertical velocity registered by an ADV across a horizontal plane is equal to the mean sediment settling velocity. For this study, a series of ADV calibrations were …

Relationships Between Erodibility And Fine-Grained Seabed Properties On Tidal To Seasonal Time-Scales, York River Estuary, Virginia, L. M. Kraatz, Carl T. Friedrichs, Grace M. Cartwright, K. A. Fall

Presentations

The complex bio-geo-physical nature of muddy particles in coastal and estuarine environments has limited our understanding of finegrained sediment dynamics. An ongoing sedimentalogical study within the York River Estuary is investigating controls on cohesive bed erodibility by assessing changes in seabed properties over varying timescales. During the spring and summer of 2010 and 2011, multiple GOMEX box cores were collected and subsampled for grain size, fecal pellet content, Gust chamber erodibility, and water content. Initial findings suggest that erodibility of the seabed increased during periods following seasonal deposition events. Higher erodibility was also generally found to coincide with peak spring …

Open Source Classroom Polling (Interactive Response) Facility, Ronald I. Greenberg

Computer Science: Faculty Publications and Other Works

The contents of the UNIX directory resulting from unzipping the .zip file provide a demonstration of a simple polling facililty that instructors can use in class any time that students have access to a web browser. This is a good way to have students work problems and see to what extent they are converging towards correct answers.

Unlike other polling facilities, this one is completely free without any restrictions on number of simultaneous users, etc. It also allows a feature most polling facilities do not in that it may be used for completely free-form answers, and the instructor can still …

Gis Data: Westmoreland County, Virginia Tidal Marsh Inventory, Marcia Berman, Harry Berquist, Carl Hershner, Sharon A. Killeen, Karinna Nunez, Tamia Rudnicky, Daniel E. Schatt, David Weiss

Data

The 2012 Tidal Marsh Inventory update for Westmoreland County, Virginia was generated using on-screen digitizing techniques in the most recent version of ArcGIS® - ArcMap while viewing conditions observed in the most recent imagery from the Virginia Base Mapping Program (VBMP). Dominant plant community types were primarily determined during field surveys from shallow-draft boats moving along the shoreline. Land-based surveys were performed in some locations. One shapefile is developed that portrays tidal marsh areas represented as polygons. A metadata file accompanies the shapefile to define attribute accuracy, data development, and any use restrictions that pertain to the data

Gis Data: City Of Virginia Beach, Virginia Tidal Marsh Inventory, Marcia Berman, Harry Berquist, Sharon A. Killeen, Carl Hershner, Karinna Nunez, Karen Reay, Tamia Rudnicky, Daniel E. Schatt

Data

The 2012 Tidal Marsh Inventory update for Virginia Beach, VA was generated using on-screen digitizing techniques in the most recent version of ArcGIS® - ArcMap while viewing conditions observed in the most recent imagery from the Virginia Base Mapping Program (VBMP). Dominant plant community types were primarily determined during field surveys from shallow-draft boats moving along the shoreline. Land-based surveys were performed in some locations. One shapefile is developed that portrays tidal marsh areas represented as polygons. A metadata file accompanies the shapefile to define attribute accuracy, data development, and any use restrictions that pertain to the data.

Gis Data: Prince William County, Virginia Tidal Marsh Inventory, Marcia Berman, Harry Berquist, Sharon A. Killeen, Carl Hershner, Karinna Nunez, Karen Reay, Tamia Rudnicky

Data

The 2012 Tidal Marsh Inventory update for Prince William County, Virginia was generated using on-screen digitizing techniques in the most recent version of ArcGIS® - ArcMap while viewing conditions observed in the most recent imagery from the Virginia Base Mapping Program (VBMP). Dominant plant community types were primarily determined during field surveys from shallow-draft boats moving along the shoreline. Land-based surveys were performed in some locations. One shapefile is developed that portrays tidal marsh areas represented as polygons. A metadata file accompanies the shapefile to define attribute accuracy, data development, and any use restrictions that pertain to the data.

Gis Data: Mathews County, Virginia Tidal Marsh Inventory, Marcia Berman, Harry Berquist, Sharon Killeen, Carl Hershner, Karinna Nunez, Karen Reay, Tamia Rudnicky, Daniel E. Schatt, David Weiss

Data

The 2012 Tidal Marsh Inventory update for Mathews County, Virginia was generated using on-screen digitizing techniques in the most recent version of ArcGIS® - ArcMap while viewing conditions observed in the most recent imagery from the Virginia Base Mapping Program (VBMP). Dominant plant community types were primarily determined during field surveys from shallow-draft boats moving along the shoreline. Land-based surveys were performed in some locations. One shapefile is developed that portrays tidal marsh areas represented as polygons. A metadata file accompanies the shapefile to define attribute accuracy, data development, and any use restrictions that pertain to the data.