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Articles 31 - 43 of 43
Full-Text Articles in Physical Sciences and Mathematics
Structural Instabilities In Strontium Titanate From First-Principles Calculations, Christopher A. Lasota
Structural Instabilities In Strontium Titanate From First-Principles Calculations, Christopher A. Lasota
Dissertations, Theses, and Masters Projects
For some time now, first-principles calculation methods have proven to be an effective tool for investigating the physics of condensed matter systems. The additional use of density functional theory (DFT) and the local density approximation (LDA) has permitted even complex materials to be studied on desktop workstations with remarkable success. The incorporation of linear response theory into these methods has extended their power, allowing investigation of important dynamical properties.;Contained within the following pages are the results of a first-principles study of SrTiO3. This transition metal oxide is often grouped with ferroelectric materials, due to its similar composition and perovskite structure. …
Semantic Software Scouts For Information Retrieval, John J. Rehder
Semantic Software Scouts For Information Retrieval, John J. Rehder
Dissertations, Theses, and Masters Projects
A new concept for information storage and retrieval is proposed that links chunks of information within and among documents based on semantic relationships and uses those connections to efficiently retrieve all the information that closely matches the user's request. The storage method is semantic hypertext, in which conventional hypertext links are enriched with semantic information that includes the strength and type of the relationship between the chunks of information being linked. A retrieval method was devised in which a set of cooperating software agents, called scouts, traverse the connections simultaneously searching for requested information. By communicating with each other and …
In-Situ Frequency-Dependent Electromagnetic Sensing For Monitoring Physical And Chemical Attributes During Chemical Processing, Jeffrey David Rogozinski
In-Situ Frequency-Dependent Electromagnetic Sensing For Monitoring Physical And Chemical Attributes During Chemical Processing, Jeffrey David Rogozinski
Dissertations, Theses, and Masters Projects
The objective of this research was to develop an in-situ sensing technique that monitors the molecular-level response of ions and dipoles to an applied electric field in order to characterize the changes in state of a polymer resin during chemical processing. This technique needs to be capable of monitoring the reaction progress not only in the laboratory setting but also in-situ in the processing tool or reaction environment. Frequency Dependent Electromagnetic Sensing (FDEMS) was selected for this task.;This dissertation investigates the applicability of FDEMS to monitoring two types of processing methods: reactive and batch reactor. The reactive processing system examined …
Data Structures For The Analysis Of Large Structured Markov Models, Andrew S. Miner
Data Structures For The Analysis Of Large Structured Markov Models, Andrew S. Miner
Dissertations, Theses, and Masters Projects
High-level modeling formalisms are increasingly popular tools for studying complex systems. Given a high-level model, we can automatically verify certain system properties or compute performance measures about the system. In the general case, measures must be computed using discrete-event simulations. In certain cases, exact numerical analysis is possible by constructing and analyzing the underlying stochastic process of the system, which is a continuous-time Markov chain (CTMC) in our case. Unfortunately, the number of states in the underlying CTMC can be extremely large, even if the high-level model is "small". In this thesis, we develop data structures and techniques that can …
Studies In Hard Pion Photoproduction, Christian Jens Wahlquist
Studies In Hard Pion Photoproduction, Christian Jens Wahlquist
Dissertations, Theses, and Masters Projects
The production of high transverse momenta mesons via polarized photoproduction can be a means of determining the parton structure of the target. at the regions of highest transverse pion momenta, kT, it can be shown that short distance, direct, pion production dominates and is sensitive to the polarized quark distributions. as the produced pions transverse momenta decreases the importance of pions produced through fragmentation following photon-gluon fusion increases. This process give us sensitivity to the form of the polarized gluon distribution. Both processes are calculable with perturbative Quantum Chromodynamics (pQCD) due to the high kT of the pion produced. Numerical …
The Attempted Synthesis Of A Phenolphthalein-Capped Beta-Cyclodextrin, Susan Elizabeth Miller
The Attempted Synthesis Of A Phenolphthalein-Capped Beta-Cyclodextrin, Susan Elizabeth Miller
Dissertations, Theses, and Masters Projects
No abstract provided.
Carbon Dynamics In A Tidal Freshwater Marsh, Scott C. Neubauer
Carbon Dynamics In A Tidal Freshwater Marsh, Scott C. Neubauer
Dissertations, Theses, and Masters Projects
The sources and fates of carbon in a tidal freshwater marsh (Sweet Hall marsh; Pamunkey River, Virginia) were determined to understand the role that these marshes play with respect to estuarine carbon cycling. A carbon gas flux model, based on measured carbon dioxide and methane fluxes, was developed to calculate annual rates of macrophyte and microalgal photosynthesis and community and belowground respiration. Because carbon fluxes out of marsh sediments may underestimate true belowground respiration if sediment-produced gases are transported through plant tissues, gross nitrogen mineralization was used as a proxy for belowground carbon respiration. Annual community respiration exceeded gross photosynthesis, …
Assessment Of Spawning And Nursery Habitat Suitability For American Shad (Alosa Sapidissima) In The Mattaponi And Pamunkey Rivers, Donna Marie Bilkovic
Assessment Of Spawning And Nursery Habitat Suitability For American Shad (Alosa Sapidissima) In The Mattaponi And Pamunkey Rivers, Donna Marie Bilkovic
Dissertations, Theses, and Masters Projects
Delineation of essential fish habitat is particularly difficult for migratory fish which utilize large expanses of habitat throughout their life history. This study's main objective was the development and evaluation of habitat assessment tools for the early life stages of American shad (Alosa sapidissima) in two coastal plain rivers. to accomplish this, shad spawning and larval nursery habitats were delineated in the Mattaponi and Pamunkey rivers using presence of eggs and larvae (1997--1999) as evidence of habitat use. A watershed habitat assessment protocol was developed and used to rate habitat based on hydrographic, physical habitat, shoreline and land use parameters. …
Ecological Interactions Between Benthic Oyster Reef Fishes And Oysters, Juliana Maria Harding
Ecological Interactions Between Benthic Oyster Reef Fishes And Oysters, Juliana Maria Harding
Dissertations, Theses, and Masters Projects
Restoration of oyster reef structures rehabilitates habitats and the multi-level ecological communities built on eastern oysters (Crassostrea virginica), the keystone species. Quantitative descriptions of ecological interactions within a habitat are required to delineate essential fish habitats for management and protection. Parallel development of primary (oysters) and secondary trophic levels (benthic fishes) offer an ecological metric of restoration progress over time. The interaction between larval oysters and larval fishes (e.g., Gobiosoma bosc, Chasmodes bosquianus) is quantitatively examined. Oyster settlement estimates for Palace Bar reef, Piankatank River, Virginia are of the same order of magnitude as field densities of recently settled oysters. …
Microgeographic Population Genetic Structure Of The Mummichog (Fundulus Heteroclitus L) Inhabiting An Industrialized Waterway, Luis Felipe Arzayus
Microgeographic Population Genetic Structure Of The Mummichog (Fundulus Heteroclitus L) Inhabiting An Industrialized Waterway, Luis Felipe Arzayus
Dissertations, Theses, and Masters Projects
No abstract provided.
Osteology, Phylogeny, And Biogeography Of The Marine Fish Family Ephippidae (Perciformes, Acanthuroidei), With Comments On Sister Group Relationships, Martin Ray Cavalluzzi
Osteology, Phylogeny, And Biogeography Of The Marine Fish Family Ephippidae (Perciformes, Acanthuroidei), With Comments On Sister Group Relationships, Martin Ray Cavalluzzi
Dissertations, Theses, and Masters Projects
The marine fish family Ephippidae comprises eight genera and 15 species of extant fishes. Spadefishes or batfishes inhabit nearshore tropical to temperate waters. They are almost circumglobal in distribution, with the highest diversity in the Indo-west Pacific and the lowest diversity in the east Pacific and west Atlantic. Fifty-nine potentially informative morphological characters, 10 outgroup taxa, and eight ingroup taxa (i.e., genera) were used to explore sister group hypotheses to the Ephippidae, as well as generate a phylogeny of the Ephippidae. Seven constraint tree analyses were utilized to examine various sister group hypotheses based on previous morphological and molecular analyses …
The Attempted Synthesis Of 4,4'-Bis(Dimethylamino)Azobenzene-3,3'-Disulfonylchloride As A Cap For Beta-Cyclodextrin, Katherine M. Ross
The Attempted Synthesis Of 4,4'-Bis(Dimethylamino)Azobenzene-3,3'-Disulfonylchloride As A Cap For Beta-Cyclodextrin, Katherine M. Ross
Dissertations, Theses, and Masters Projects
No abstract provided.
A Study Of The Aging Of Polyamide-11 Based On Molecular Weight Measurements, Yao Lin
A Study Of The Aging Of Polyamide-11 Based On Molecular Weight Measurements, Yao Lin
Dissertations, Theses, and Masters Projects
No abstract provided.