• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 28
  • 7
  • 3
  • 3
  • 1
  • 1
  • 1
  • Tagged with
  • 58
  • 9
  • 7
  • 6
  • 6
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Genetic Pore Types and Their Relationship to Reservoir Quality: Canyon Formation (Pennsylvanian), Diamond M Field, Scurry County, Texas

Barry, Travis 2011 December 1900 (has links)
Carbonate reservoirs may have a variety of porosity types created by depositional, diagenetic, and fracture processes. This leads to the formation of complex pore systems, and in turn creates heterogeneities in reservoir performance and quality. In carbonate reservoirs affected by diagenesis and fracturing, porosity and peremeability can be independent of depositional facies or formation boundaries; consequently, conventional reservoir characterization methods are unreliable for predicting reservoir flow characteristics. This thesis provides an integrated petrographic, stratigraphic, and petrophysical study of the 'Canyon Reef' reservoir, a Pennsylvanian phylloid algal mound complex in the Horseshoe atoll. Core descriptions on three full-diameter cores led to the identification of 5 distinct depositional facies based on fundamental rock properties and biota. Fifty-four thin sections taken from the core were described are pores were classified using the Humbolt modification of the Ahr porosity classification. In order to rank reservoir quality, flow units were established on the basis of combined porosity and permeability values from core analysis. A cut off criterion for porosity and permeability was established to separate good and poor flow units. Ultimately cross sections were created to show the spatial distribution of flow units in the field.
22

Systematics and palaeobiology of the crested hadrosaurine Saurolophus from Canada and Mongolia

Bell, Phil Unknown Date
No description available.
23

The Ghosts of Horseshoe Bend: Myth, Memory, and the Making of a National Battlefield

January 2014 (has links)
abstract: This research explores the various and often conflicting interpretations of the Battle of Horseshoe Bend, an event seemingly lost in the public mind of twenty-first century America. The conflict, which pitted United States forces under the command of Major General Andrew Jackson against a militant offshoot of the Creek Confederacy, known as the Redsticks, ranks as the single most staggering loss of life in annals of American Indian warfare. Today, exactly 200 years after the conflict, the legacy of Horseshoe Bend stands as an obscure and often unheard of event. Drawing upon over two centuries of unpublished archival data, newspapers, and political propaganda this research argues that the dominate narrative of Northern history, the shadowy details of the War of 1812, and the erasure of shameful events from the legacy of westward expansion have all contributed to transform what once was a battle of epic proportions, described by Jackson himself as an "extermination," into a seemingly forgotten affair. Ultimately, the Battle of Horseshoe Bend's elusiveness has allowed for the production of various historical myths and political messages, critiques and hyperboles, facts and theories. Hailed as a triumph during the War of 1812, and a high-water mark by the proponents of Manifest Destiny, Jackson's victory has also experienced its fair share of American derision and disregard. Whereas some have criticized the battle as a "cold blooded massacre," others have glorified it as a touchstone of American masculinity, and excused it as a natural event in the unfolding of human evolution. Despite the battle's controversial nature, on 3 August 1956, President Dwight D. Eisenhower, a strong supporter of the National Park Service, approved act HR 11766 establishing Horseshoe Bend National Military Park, the very first national park in the state of Alabama. Hailed and forgotten, silenced and celebrated, exploited and yet largely unknown. This research explores what happened after the smoke cleared at the Battle of Horseshoe Bend. It is a story about the production of history, the power of the past, and the malleability of the American mind. / Dissertation/Thesis / M.A. History 2014
24

Problema restrito dos três corpos / Restrict three body problem

Fernando Pereira Micena 23 February 2007 (has links)
O problema de n?corpos é um dos problemas mais importantes em Sistemas Dinâmicos. Nós estudamos o modelo do problema dos três corpos restrito introduzido por Sitnikov. Nesse modelo os corpos primários tem a mesma massa e o terceiro corpo é de massa muito pequena com respeito aos corpos primários. Usando os métodos de Alekseev, nós mostramos a existência de uma ?ferradura de Smale?como um subsistema da dinâmica do terceiro corpo e concluímos ricas conseqüências probabilísticas. Nós também estudamos o problema pelo método de Melnikov / The n?body problem is one of the most important problems in dynamical systems. We study the model introduced by Sitnikov of restricted three body problem. In this model the primaries are of equal mass and the third body is very small with respect to the primaries. Using methods of Alekseev, we show the existence of ?Smale horseshoe?as a subsystem of the dynamic of the third body and conclude rich probabilistic consequences. We also study the same problem by Melnikov?s method
25

Zařízení pro indukční ohřev s výkonem 2,5kW / Device for induction heating with a power of 2,5kW

Krist, Petr January 2014 (has links)
This thesis deals with designing of an induction heating of small iron parts. This device should be primarily designed for a farrier practice or an artistic blacksmithing. Considering the practice, the referential heated iron part will be a horseshoe. The basis of this device is a power inverter with serial resonant circuit connected to inverter as a load. This thesis contains designing and development of electrical and mechanical parts of whole device. It means control circuits, resonant circuit, box for heated part, etc. At the end of this thesis is realization of the device, electrifying, optimization and testing. During the test the horseshoe was heated close to demanded temperature.
26

Horseshoe Bending Machine : Bending Mechanism

Quesada Díaz, Raquel January 2014 (has links)
Horseshoes are manufactured metal plates developed in an extensive assortment of materials and shapes and their main function is to protect the horse’s hooves and legs against abrasion and rupture. After a certain period of time the horseshoes are lost, worn out, or the hoof needs to be treated. Horseshoeing is a repetitive time consuming process for the farrier who has to heat the horseshoe inside a forge until it reaches the required temperature and shape it with a hammer until it fits perfectly to the horses’ hoof. The main goal of this project is to develop a horseshoe bending machine able to shape the horseshoe so its shape fits perfectly the horse’s hoof. The calculation of the bending force needed to be applied to the horseshoe in order to provoke a plastic deformation will be done with Euler-Bernoulli beam theory. The bending force is then used to design and dimension each element of the bending mechanism so that it may be able to resist the stresses and prevent the parts from collapsing during its working life span. A study of the springback effect will be done followed by the analysis of the hertzian contact stresses between the rollers and the horseshoe. In addition, a clamping system is selected to constrain the movements of the horseshoe during the bending process. This machine will reduce the final user’s horse maintenance costs at the same time that makes the fitting process easier and less demanding, which will improve the farrier’s working life span and quality.
27

Spatial Ecology of American Horseshoe Crab (Limulus polyphemus) in Chatham, Cape Cod, Ma: Implications for Conservation and Management

Martinez, Sarah E 01 January 2012 (has links) (PDF)
Information regarding spawning site fidelity and movement patterns of the American horseshoe crab (Limulus polyphemus) is crucial for developing effective conservation and management strategies on the correct spatial scale. To investigate the spatial ecology of American horseshoe crabs, 75 adult animals were tracked off the coast of Chatham, Cape Cod, MA from June 2010 to November 2011 using acoustic telemetry. Two groups of horseshoe crabs were tagged in spawning habitats (separated by ~2.0 km) with differing commercial harvesting pressure: one group inside Stage Harbor, where harvesting is permitted and the other within a Marine Protected Area (MPA) where harvesting is prohibited. Network analysis revealed that horseshoe crabs exhibited fidelity to spawning habitat, but not necessarily to the habitat where they were initially tagged. Fifty-nine percent of horseshoe crabs tagged inside Stage Harbor were detected in the MPA and 13% of horseshoe crabs tagged in the MPA were detected inside Stage Harbor. Although horseshoe crabs were utilizing both spawning habitats, predictive modeling revealed little temporal overlap, suggesting that horseshoe crabs from the two spawning habitats represent local populations. Isolated and local populations are more susceptible to overexploitation than are larger populations with many migrants. To protect against overharvest and extinction of isolated and local populations, the correct identification of management units (MUs) must be a priority of fisheries managers. Horseshoe crab populations around Cape Cod, Massachusetts and New England behave differently, requiring the collection of more information so that conservation tools such as MUs or MPAs can be used most effectively.
28

The Effects of Localized Blade Endwall Suction on Surface Heat Transfer

Hollis, Rebecca M. 08 September 2009 (has links)
No description available.
29

Bayesian Hierarchical Methods and the Use of Ecological Thresholds and Changepoints for Habitat Selection Models

Pooler, Penelope S. 03 January 2006 (has links)
Modeling the complex relationships between habitat characteristics and a species' habitat preferences pose many difficult problems for ecological researchers. These problems are complicated further when information is collected over a range of time or space. Additionally, the variety of factors affecting these choices is difficult to understand and even more difficult to accurately collect information about. In light of these concerns, we evaluate the performance of current standard habitat preference models that are based on Bayesian methods and then present some extensions and supplements to those methods that prove to be very useful. More specifically, we demonstrate the value of extending the standard Bayesian hierarchical model using finite mixture model methods. Additionally, we demonstrate that an extension of the Bayesian hierarchical changepoint model to allow for estimating multiple changepoints simultaneously can be very informative when applied to data about multiple habitat locations or species. These models allow the researcher to compare the sites or species with respect to a very specific ecological question and consequently provide definitive answers that are often not available with more commonly used models containing many explanatory factors. Throughout our work we use a complex data set containing information about horseshoe crab spawning habitat preferences in the Delaware Bay over a five-year period. These data epitomize some of the difficult issues inherent to studying habitat preferences. The data are collected over time at many sites, have missing observations, and include explanatory variables that, at best, only provide surrogate information for what researchers feel is important in explaining spawning preferences throughout the bay. We also looked at a smaller data set of freshwater mussel habitat selection preferences in relation to bridge construction on the Kennerdell River in Western Pennsylvania. Together, these two data sets provided us with insight in developing and refining the methods we present. They also help illustrate the strengths and weaknesses of the methods we discuss by assessing their performance in real situations where data are inevitably complex and relationships are difficult to discern. / Ph. D.
30

Experimental Investigation of Turbulent Flows at Smooth and Rough Wall-Cylinder Junctions

Apsilidis, Nikolaos 10 January 2014 (has links)
Junction flows originate from the interaction between a fluid moving over a wall with an obstacle mounted on the same surface. Understanding the physics of such flows is of great interest to engineers responsible for the design of systems consisting of wall-body junctions. From aerodynamics to turbomachinery and electronics to bridge hydraulics, a number of phenomena (drag, heat transfer, scouring) are driven by the behavior of the most prominent feature of junction flows: the horseshoe vortex system (HVS). Focusing on turbulent flows, the complex dynamics of the HVS is established through its unsteadiness and non-uniformity. The fundamentals of this dynamically-rich phenomenon have been described within the body of a rapidly-expanding literature. Nevertheless, important aspects remain inadequately understood and call for further scrutiny. This study emphasized three of them, by investigating the effects of: model scale, wall roughness, and bed geometry. High-resolution experiments were carried out using Particle Image Velocimetry (PIV). Statistical analyses, vortex identification schemes, and Proper Orthogonal decomposition were employed to extract additional information from the large PIV datasets. The time-averaged topology of junction flows developing over a smooth and impermeable wall was independent of the flow Reynolds number, Re (parameter that expresses the effects of scale). On the contrary, time-resolved analysis revealed a trend of increasing vorticity, momentum, and eruptions of near-wall fluid with Re. New insights on the modal dynamics of the HVS were also documented in a modified flow mechanism. Wall roughness (modeled with a permeable layer of crushed stones) diffused turbulence and vorticity throughout the domain. This effect manifested with high levels of intermittency and spatial irregularity for the HVS. Energetic flow structures were also identified away from the typical footprint of the HVS. Finally, a novel implementation of PIV allowed for unique velocity measurements over an erodible bed. It was demonstrated that, during the initial stages of scouring, the downflow at the face of the obstacle becomes the dominant flow characteristic in the absence of the HVS. Notwithstanding modeling limitations, the physical insight contributed here could be used to enhance the design of systems with similar flow and geometrical characteristics. / Ph. D.

Page generated in 0.0478 seconds