Digital Commons Network^™

Mass Loss History Of Evolved Stars, Kathleen M. Geise

Electronic Theses and Dissertations

We provide high-resolution maps of the circumstellar dust shells of several dozen Asymptotic Giant Branch (AGB) stars using data from the Spitzer space telescope Multiband Imaging Photometer (MIPS) imaged at 70µm. AGB stars are the major contributors of chemical elements such as carbon, oxygen and silicon, which are essential to the existence of life in the universe, through mass loss processes that take place at the surface of the star. We probe the spatial distribution of cold (~40 K) dust grains in order to trace the history of mass loss from the observed radial density variation in these shells. Our …

Trends In Heavy-Duty Diesel Emissions And Analyses Of Colorado's Light-Duty Vehicle Inspection And Maintenance Program, Brent G. Schuchmann

Electronic Theses and Dissertations

Emission trends are reported and discussed resulting from the multi-year study of Heavy-Duty Diesel Vehicles (HDDV) at the Port of Los Angeles and at a weigh station in Peralta also in the L.A. basin. Remote sensing data were also collected from the Port of Houston and compared to the data from California. As part of San Pedro Bay Ports Clean Air Action Plan (CAAP) to fast track the turnover rate of cleaner trucks, many truck operators have been subject to modifying their trucks, or have purchased new trucks, with more advanced control technologies to reduce exhaust particulate matter (PM) and …

A Study Of Transient Variations In Cosmic Ray Proton Intensities Using Bess-Polar I Data, Neeharika Thakur

Electronic Theses and Dissertations

The intensities of galactic cosmic rays are modulated upon entering the heliosphere. These variations, defined as solar modulations, are classified as long-term or transient modulations based on their durations.

Studies have correlated the transient variations with the characteristics of the solar wind and the interplanetary magnetic field. Therefore, studies of transients augment our understanding of physical processes in the interplanetary medium. Processes causing transient variations may also induce geomagnetic storms. Precise measurements of cosmic ray fluxes during a transient phenomenon will have immense use in validating models of space weather prediction.

BESS (Balloon-borne Experiment with a Superconducting Spectrometer), a US-Japanese …

Colorado's Large Snow Events' Impact On Tree Ring Growth And Dillon Reservoir, Katrina Leona Marzetta

Electronic Theses and Dissertations

Meteorological observations from 1894 through 2010 suggest that 17 historically large snow events occurred in the mountains of Colorado within Denver's water supply region. Of these 16 events, 14 can be identified in precipitation sensitive tree ring records as positive climatic pointer years. If these storms were to occur today, they would have the potential to fill reservoirs in Denver Water's supply system, even after years of sustained drought. These "drought busters" have the potential to refill Dillon Reservoir by increasing average yearly inflow up to 146% of the previous year's inflow. Such drought busters can help Denver recover from …

Minimax And Maximin Fitting Of Geometric Objects To Sets Of Points, Yan B. Mayster

Electronic Theses and Dissertations

This thesis addresses several problems in the facility location sub-area of computational geometry. Let S be a set of n points in the plane. We derive algorithms for approximating S by a step function curve of size k < n, i.e., by an x-monotone orthogonal polyline ℜ with k < n horizontal segments. We use the vertical distance to measure the quality of the approximation, i.e., the maximum distance from a point in S to the horizontal segment directly above or below it. We consider two types of problems: min-ε, where the goal is to minimize the error for a …

Memory Access Patterns For Cellular Automata Using Gpgpus, James Michael Balasalle

Electronic Theses and Dissertations

Today's graphical processing units have hundreds of individual processing cores that can be used for general purpose computation of mathematical and scientific problems. Due to their hardware architecture, these devices are especially effective when solving problems that exhibit a high degree of spatial locality. Cellular automata use small, local neighborhoods to determine successive states of individual elements and therefore, provide an excellent opportunity for the application of general purpose GPU computing. However, the GPU presents a challenging environment because it lacks many of the features of traditional CPUs, such as automatic, on-chip caching of data. To fully realize the potential …

Simulation, Application, And Resilience Of An Organic Neuromorphic Architecture, Made With Organic Bistable Devices And Organic Field Effect Transistors, Robert A. Nawrocki

Electronic Theses and Dissertations

This thesis presents work done simulating a type of organic neuromorphic architecture, modeled after Artificial Neural Network, and termed Synthetic Neural Network, or SNN. The first major contribution of this thesis is development of a single-transistor-single-organic-bistable-device-per-input circuit that approximates behavior of an artificial neuron. The efficacy of this design is validated by comparing the behavior of a single synthetic neuron to that of an artificial neuron as well as two examples involving a network of synthetic neurons. The analysis utilizes electrical characteristics of polymer electronic elements, namely Organic Bistable Device and Organic Field Effect Transistor, created in the laboratory at …

Approximate Transversals Of Latin Squares, Jon Kyle Pula

Electronic Theses and Dissertations

A latin square of order n is an n by n array whose entries are drawn from an n-set of symbols such that each symbol appears precisely once in each row and column. A transversal of a latin square is a subset of cells that meets each row, column, and symbol precisely once.

There are many open and difficult questions about the existence and prevalence of transversals. We undertake a systematic study of collections of cells that exhibit regularity properties similar to those of transversals and prove numerous theorems about their existence and structure. We hope that our results …