Physical Sciences and Mathematics Commons^™

Climatologically Forced Coherence Between Diverse Juvenile Populations In The Virginia Tributaries To The Chesapeake Bay, Thomas C. Mosca Iii

Dissertations, Theses, and Masters Projects

Long term trends in juvenile recruitment of oyster, bluecrab, and 24 species of finfish in a large temperate estuary (lower Chesapeake Bay, USA) are coherent across the three major tributaries (the Virginia rivers James, York, and Rappahannock). The driving force for these long term trends is geographically large in scale. Anomalous winters in the mid 1970's, with the warmest years on record followed immediately by the coldest, caused a severe perturbation in population dynamics. The extreme conditions caused the system to shift, with recruitment patterns following temperatures by a one year lag. Following this anomalous episode, smoothed mean winter water …

Response Modes Of The Lower Chesapeake Bay Wave Field, Katherine L. Farnsworth

Dissertations, Theses, and Masters Projects

An extensive wave monitoring program was conducted in the lower Chesapeake Bay from fall 1989 through spring 1995. From October 23, 1992 - April 20, 1993 the Virginia Institute of Marine Science deployed an aluminum tetrapod containing wave and current sensing and recording equipment in the Thimble Shoal region of the lower Chesapeake Bay. Measurements were made in half hour bursts every three hours to document the area’s dynamic wave characteristics. It was shown previously by Boon et al. (1990 - 1996) that a bimodal frequency distribution of waves in the Thimble Shoal region existed, which was not seen in …

Microstructural Characterization Of An Ultra-High-Performance Polyimide, April Heather Baugher

Dissertations, Theses, and Masters Projects

The motivation for this study was to further characterize a relatively new high-temperature polymer for application as a matrix resin for carbon fiber composites. The two primary questions addressed in this study dealt with the structural and chemical changes occurring in these polymers on exposure to high temperature.;To investigate the structural changes in the heat-treated samples, a positron annihilation lifetime spectrometer was designed, built and optimized. Because the lifetime of a positron in a material reflects the electronic structure of the material in which it annihilates, measurements by positron annihilation lifetime spectroscopy can be used to investigate changes in a …

The Thermal Cure Of Phenylethynyl-Terminated Polyimides And Selected Model Compounds, Karen H. Wood

Dissertations, Theses, and Masters Projects

The ability to process high performance polymers into useful adhesives and high quality composites has been significantly advanced by synthetic techniques in which oligomers terminated with reactive groups cure or crosslink at elevated temperature after the article has been fabricated. Several matrix resin systems of considerable interest to the aerospace community utilize phenylethynyl terminated imide (PETI) technology developed at the Langley Research Center to achieve this advantage. This work addresses the cure chemistry of PETI oligomers.;The thermal cure of selected oligomers and model compounds was studied using a variety of analytical techniques including differential scanning calorimetry, high pressure liquid chromatography, …

On-Line System Identification For Control System Applications In Particle Accelerators, Mahesh Chowdhary

Dissertations, Theses, and Masters Projects

Particle accelerators require a number of feedback systems in order to stabilize a variety of parameters. The Continuous Electron Beam Accelerator at Thomas Jefferson National Accelerator Facility presents a unique set of control and identification problems. This accelerator produces a continuous electron beam with energies between 0.5 and 4.0 GeV to be delivered to the experimental halls. In order to meet stringent beam quality requirements specified by the experimental halls, the position and the energy of the electron beam needs to stabilized at various locations in the accelerator.;A number of noise measurement tests were conducted at various locations in the …

Radiation-Induced Luminescence In Terbium-Doped Silicate Glasses, Michael Stuart West

Dissertations, Theses, and Masters Projects

The purpose of this study is to characterize radiation-induced luminescence of terbium-doped silicate glasses. Experiments performed investigated the optical properties, isothermal time-evolution, and temperature dependence of the radiation-induced luminescence of two commercially available terbium-doped glasses. A problem common to this type of glass is the persistent luminescence, or afterglow, that occurs following the end of excitation from an external source of radiation. While the processes that govern characteristic luminescence of rare earth ions, including terbium, are well understood, the processes that give rise to afterglow in doped glasses are not. Identifying the source of long-term luminescence is essential for controlling …

Cp Violation In K-Long Decays, Gregory Dominick Dorata

Dissertations, Theses, and Masters Projects

The main topic of this dissertation concerns alternative models of CP violation and the rates predicted by these models for the particular decay {dollar}K\sb{lcub}L{rcub}\to\pi\sp0\nu\bar\nu .{dollar} This decay is promising as a probe of the origin of CP violation in the kaon system. It is virtually free of hadronic uncertainties and its branching ratio would (along with a measurement of the CP asymmetry in {dollar}B\sbsp{lcub}d{rcub}{lcub}0{rcub}\to\psi K\sb{lcub}S{rcub}){dollar} allow a determination of all the elements of the CKM matrix (assuming all CP violation arises from the CKM matrix).;The first group of models of CP violation considered consists of three extensions of the Higgs …

Thermal Lattice Boltzmann Simulations Of Variable Prandtl Number Turbulent Flow, Min Soe

Dissertations, Theses, and Masters Projects

With the advent of massively parallel processor machines, thermal lattice Boltzmann equation (TLBE) techniques offer an attractive way of handling turbulence simulations. TLBE is new form of DNS (direct numerical simulation method)--with the important advantages of being ideal for multi-parallel processors as well as being able to handle complicated geometries. Since there are many kinetic models that will reproduce the macroscopic nonlinear (compressible) transport equations, TLBE chooses that subset which can be readily solved on a discrete spatial lattice. The lattice geometry must be so chosen that the discrete phase representation of TLBE will not taint the rotational symmetric continuum …

The Synthesis, Characterization, And Molecular Modeling Of Cyclic Arylene Ether Oligomers, Sheeba Ahmed

Dissertations, Theses, and Masters Projects

Cyclophanes are a family of bridged cyclic aromatic compounds that have found extensive applications in host-guest chemistry, molecular recognition, biomimetics and most recently as precursors in ring-opening polymerizations.;This research presents the synthesis of several novel cyclic arylene ether oligomers, based on 1,3-bis(4-fluorobenzoyl) benzene and 3,3{dollar}\sp\prime{dollar}-methylene diphenol and 3,3{dollar}\sp\prime{dollar}-(ethylene dioxy) diphenol, and their characterization by LC-MS/MS, 1-D {dollar}\sp1{dollar}H-NMR and x-ray crystallography. Electrospray ionization (ES) along with MS/MS was used to characterize cyclic oligomers of molecular weight up to 1600 Da. The thermal properties of these cyclic oligomers were studied by differential scanning calorimetery (DSC) and thermal gravimetric analysis (TGA).;These cyclic oligomers …

Propagation Of Rayleigh Waves In Thin Films, Agus A. Ananda

Dissertations, Theses, and Masters Projects

With the advent of thin film technology and more recently its applications in microelectronics and control of surface properties, the interest in mechanical properties of thin films has grown tremendously. Mechanical defects such as creep, fracture and adhesion loss, play a very important role in physical instabilities of thin film materials. An acoustic microscope has been built to study mechanical properties of thin-films. The microscope operates at a nominal frequency of 50 MHz. Rayleigh surface waves velocities on the surface of film-substrate systems were measured from V(z) curves generated by the acoustic microscope. V(z) curves are produced from interference between …

Development Of Supercritical Fluid Extraction (Sfe) For The Determination Of Polychlorinated Biphenyls In Tissues Of Aquatic Biota, Michael O. Gaylor

Dissertations, Theses, and Masters Projects

No abstract provided.

The Promotion Of Poly(Methyl Methacrylate) Depolymerization By Metal-Based Initiators, Jason Andrew Macko

Dissertations, Theses, and Masters Projects

No abstract provided.

Characterization Of Epoxy-Amine Systems And Nylon-11 And Pvdf Degradation, Wendy Raquel Mahler

Dissertations, Theses, and Masters Projects

No abstract provided.

Semiclassical Model Of Λ-Doublet States In Diatomic Molecules, Laurie J. Kovalenko, John B. Delos

Arts & Sciences Articles

An intuitive picture of Λ-doubling in diatomic molecules is presented using a semiclassical theory. A common view of Λ-doubling as arising from electrons “lagging” behind the rotating internuclear axis is shown to be misleading; rather, the eigenfunctions are symmetric about the molecular axes and can be expressed as a superposition of pure nonrotating orbitals and travelling waves. These results are shown to be consistent with a full quantum treatment. We also examine, for the first time, time-dependent states, by monitoring expectation values of electronic- and nuclear-angular momenta. For low rotation frequency, the expectation value of the electronic-angular momentum locks onto …

Saltwater Angling And Its Economic Importance To Virginia, James Kirkley, David Kerstetter

Reports

No abstract provided.

Virginia Game Fish Tagging Program Annual Report 1996, Cm Bain Iii, John A. Lucy

Reports

The Virginia Game Fish Tagging Program (VGFfP), a cooperative project of the Virginia Marine Resources Commission and the Virginia Institute of Marine Science (VIMS), enjoyed its second full year of operation in 1996. Participation in the project, which is funded with revenues generated by Virginia's saltwater recreational fishing license, nearly doubled with 127 anglers volunteering as taggers compared to 64 in 1995.

Yellow Sea & East China Sea Bibliography, Nicole D. Scott, Patricia T. Carrier, John D. Milliman

Reports

No abstract provided.

Public Beach Assessment Report Gloucester Point Public Beach, Gloucester County, Virginia, Donna A. Milligan, C. Scott Hardaway Jr., George R. Thomas

Reports

Gloucester Point Public Beach is located at the southern end of Gloucester County, Virginia on the York River. It is a southeastward facing shoreline about 960 ft long and it is part of a larger stretch of moderately low shore between Sarah Creek and the George P. Coleman Bridge. While no shoreline improvement projects have taken place at the public beach, shore protection projects updrift and including the Virginia Institute of Marine Science (VIMS) affect it. In 1983, erosion along the shoreline at VIMS just updrift of the public beach led to the installation of a riprap revetment in front …

Public Beach Assessment Report Yorktown Public Beach, Yorktown, Virginia, Donna A. Milligan, C. Scott Hardaway Jr., George R. Thomas

Reports

No abstract provided.

Distribution Of Submerged Aquatic Vegetation In The Chesapeake Bay And Tributaries And Chincoteague Bay - 1995, Robert J. Orth, Judith F. Nowak, Gary F. Anderson, David J. Wilcox, Jennifer R. Whiting, Leah S. Nagy

Reports

No abstract provided.

The Virginia Wetlands Report Vol. 11, No. 3, Virginia Institute Of Marine Science

Virginia Wetlands Reports

• Great Blue Heron. Julie G. Bradshaw
• Weakfish. Lyle Varnell
• Geographic Information Systems Support Tributary Strategy Planning in Virginia. Marcia Berman
• Wetlands and Regional Watershed Management. Katie Hopkins
• Cranberries. Pam Mason
• What is a groin and how does it work? William Roberts

Semiclassical Scattering In A Circular Semiconductor Microstructure, C. D. Schwieters, J. A. Alford, John B. Delos

Arts & Sciences Articles

The conductance of a microscopic junction shows fluctuations caused by quantum interference of waves that follow different paths between the leads. We give a semiclassical formula for these fluctuations. The theory utilizes trajectories which travel between the centers of the lead apertures; it also incorporates diffraction at these apertures. We extend the theory to include ‘‘ghost paths,’’ which scatter diffractively off the lead mouths. Semiclassical S-matrix elements are computed for a circular junction over a range of Fermi wave numbers, and the large-scale structure of these matrix elements shows good agreement with quantum results. Finally, we propose a hypothesis …

Detritus: Mother Nature's Rice Cake, Pamela Mason, Lyle M. Varnell, Virginia Institute Of Marine Science, Wetlands Program

Reports

No abstract provided.

Slow Down, D. Chris Benner, Rodelle A. Benner

Arts & Sciences Articles

No abstract provided.

Computational Algebra Applications In Reliability, G Hartless, Lawrence Leemis

Arts & Sciences Articles

Reliability analysts are typically forced to choose between using an 'algorithmic programming language' or a 'reliability package' for analyzing their models and lifetime data. This paper shows that computational languages can be used to bridge the gap to combine the flexibility of a programming language with the ease of use of a package. Computational languages facilitate the development of new statistical techniques and are excellent teaching tools. This paper considers three diverse reliability problems that are handled easily with a computational algebra language: system reliability bounds; lifetime data analysis; and model selection.

Research Needs For The Risk Assessment Of Health And Environmental Effects Of Endocrine Disruptors: A Report Of The Us Epa-Sponsored Workshop, Rj Kavlock, Gp Daston, C Derosa, P Fennercrisp, Le Gray, S Kaattari, Et Al

VIMS Articles

The hypothesis has been put forward that humans and wildlife species have suffered adverse health effects after exposure to endocrine-disrupting chemicals. Reported adverse effects include declines in populations, increases in cancers, and reduced reproductive function. The U.S. Environmental Protection Agency sponsored a workshop in April 1995 to bring together interested parties in an effort to identify research gaps related to this hypothesis and to establish priorities for future research activities. Approximately 90 invited participants were organized into work groups developed around the principal reported health effects-carcinogenesis, reproductive toxicity, neurotoxicity, and immunotoxicity--as well as along the risk assessment paradigm--hazard identification, dose-response …

Bifurcation Of The Periodic Orbits Of Hamiltonian Systems: An Analysis Using Normal Form Theory, D. A. Sadovskii, John B. Delos

Arts & Sciences Articles

We develop an analytic technique to study the dynamics in the neighborhood of a periodic trajectory of a Hamiltonian system. The theory begins with Poincaré and Birkhoff; major modern contributions are due to Meyer, Arnol'd, and Deprit. The realization of the method relies on local Fourier-Taylor series expansions with numerically obtained coefficients. The procedure and machinery are presented in detail on the example of the ‘‘perpendicular’’ (z=0) periodic trajectory of the diamagnetic Kepler problem. This simple one-parameter problem well exhibits the power of our technique. Thus, we obtain a precise analytic description of bifurcations observed by J.-M. Mao …

Methods Of Risk Analysis: Traditional And Ecological Approaches, John Buie, Virginia Institute Of Marine Science, Wetlands Program

Reports

No abstract provided.

Advances In Wetland Status And Trends Monitoring Cumulative Error Comparisons, Stacie A.C. Nelson, Virginia Institute Of Marine Science, Wetlands Program

Reports

No abstract provided.

Restoration And Creation Of Forested Wetlands: A Guide, Cathy Palmintier, Bonny Lee Appleton, Virginia Institute Of Marine Science, Wetlands Program

Reports

No abstract provided.