Physical Sciences and Mathematics Commons^™

Development Of A Simulation System For Testing Hardwood Plantation Silviculture, Christopher Michael Oswalt

Doctoral Dissertations

Hardwood plantations are becoming increasingly important in the United States. To date, many foresters have relied on a conifer plantation model as the basis of establishing and managing hardwood plantations. The monospecific approach suggested by the conifer plantation model does not appear to provide for the development of quality hardwood logs similar to those found in natural hardwood stands. Thus, there is interest in creating mixed species plantations to simulate natural hardwood stand development.

A simulation system, CherrybarkSQ, was developed to provide a platform for investigating the impacts of mixed species management of hardwood plantations on the stem quality of …

Determination Of Mineral Abundances In Ordinary Chondrites Using Powder X-Ray Diffraction: Applications To Parent Body Processes And Asteroid Spectroscopy, Tasha L. Dunn

Doctoral Dissertations

The ordinary chondrites, the most abundant group of meteorites, are divided into three chemical groups (H, L, and LL), which are distinguished based on variations in bulk composition and iron content. Although ordinary chondrites are relatively abundant, our understanding of their formation has been hampered by an inability to accurately measure the abundances of minerals that they contain. Here I use power x-ray diffraction (XRD) to quantify the modal abundances of 48 unbrecciated ordinary chondrite falls, which represent the complete petrologic range of equilibrated ordinary chondrites (types 4-6).

Although the degree of metamorphism varies within each ordinary chondrite group, many …

Establishment Of A Structure-Activity Relationship In Heterogeneous Titanosilicate Catalysts For Olefin Epoxidation Via A Building Block Method, Geoffrey T. Eldridge

Doctoral Dissertations

The non-aqueous building block (NABB) method is a synthetic method that has the goal of producing atomically dispersed, well-defined, single-site heterogeneous catalysts. The active sites of these catalysts are able to be structured on the nanometer scale using the process of sequential additions. The method is designed in such a manner that it should be able to produce a series of catalysts each with a unique, well-defined, single active site. This series of catalysts can then be used to elucidate the structure-activity relationship for the active site in a particular chemical reaction.

In this dissertation a new building block, …

Synthesis, Characterization, And Applications Of Responsive Polymer Brush-Grafted Particles, Dejin Li

Doctoral Dissertations

In this dissertation, I present the synthesis, characterization, and applications of responsive polymer brush-grafted silica/crosslinked polymeric particles. The polymer brush-grafted particles were synthesized by surface-initiated "living"/controlled radical polymerizations from initiator-functionalized particles in the presence of free initiators. Two types of core particles were used in my research. One was silica particles, which were synthesized by Stöber method. The other one was crosslinked PtBA particles, which were prepared by seeded emulsion polymerization. The responsive properties of the grafted polymer brushes were characterized with ¹H NMR and Dynamic Light Scattering.

Nanomagnets: Magnetic Properties And Inelastic Neutron Scattering Studies, Jason T. Haraldsen

Doctoral Dissertations

In this thesis, small quantum spin systems, known as nano-magnets or molecular magnets, have been investigated. This is an area of great interest in the development of nanotechnology and quantum computers. Previous research on molecular magnets has concentrated on large, complex materials, which have many magnetic ions competing for superexchange pathways. Due to the large number of magnetic ions, the Hamiltonians resulted in very large Hilbert spaces, which makes it difficult for the magnetic interactions to be characterized and analyzed. Through the analysis of smaller and simpler magnetic clusters, insight can be gained from the interactions of the magnetic ions …

Imaging By Detection Of Infrared Photons Using Arrays Of Uncooled Micromechanical Detectors, Dragoslav Grbovic

Doctoral Dissertations

The objective of this dissertation was to investigate the possibility of uncooled infrared imaging using arrays of optically-probed micromechanical detectors. This approach offered simplified design, improved reliability and lower cost, while attaining the performance approaching that contemporary uncooled imagers. Micromechanical infrared detectors undergo deformation due to the bimetallic effect when they absorb infrared photons. The performance improvements were sought through changes in structural design such as modification and simplification of detector geometry as well as changes in the choice of materials. Detector arrays were designed, fabricated and subsequently integrated into the imaging system and relevant parameters, describing the sensitivity and …

A Finite State Machine Approach To Cluster Identification Using The Hoshen-Kopelman Algorithm, Matthew L. Aldridge

Doctoral Dissertations

The purpose of this study was to develop an efficient finite state machine implementation of the eponymous Hoshen-Kopelman cluster identification algorithm using the nearest-eight neighborhood rule suitable to applications such as computer modeling for landscape ecology. The implementation presented in this study was tested using both actual land cover maps, as well as randomly generated data similar to those in the original presentation of the Hoshen-Kopelman algorithm for percolation analysis. The finite state machine implementation clearly outperformed a straightforward adaptation of the original Hoshen-Kopelman algorithm on either data type. Research was also conducted to explore the finite state machine's performance …

Parallel Simulation Of Individual-Based, Physiologically-Structured Population And Predator-Prey Ecology Models, Jeffrey A. Nichols

Doctoral Dissertations

Utilizing as testbeds physiologically-structured, individual-based models for fish and Daphnia populations, techniques for the parallelization of the simulation are developed and analyzed. The techniques developed are generally applicable to individual-based models. For rapidly reproducing populations like Daphnia which are load balanced, then global birth combining is required. Super-scalar speedup was observed in simulations on multi-core desktop computers.

The two populations are combined via a size-structured predation module into a predator-prey system with sharing of resource weighted by relative mass. The individual-based structure requires multiple stages to complete predation.

Two different styles of parallelization are presented. The first distributes both populations. …

Zero-Divisor Graphs, Commutative Rings Of Quotients, And Boolean Algebras, John D. Lagrange

Doctoral Dissertations

The zero-divisor graph of a commutative ring is the graph whose vertices are the nonzero zero-divisors of the ring such that distinct vertices are adjacent if and only if their product is zero. We use this construction to study the interplay between ring-theoretic and graph-theoretic properties. Of particular interest are Boolean rings and commutative rings of quotients.