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  • 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.
191

Development of a Compositional Reservoir Simulator for Asphaltene Precipitation Based on a Thermodynamically Consistent Model

Gonzalez Abad, Karin G 16 December 2013 (has links)
A rigorous three-phase asphaltene precipitation model was implemented into a compositional reservoir simulator to represent and estimate the reduction of porosity and permeability responsible for productivity impairment. Previous modeling techniques were computationally inefficient, showed thermodynamic inconsistencies, or required special laboratory experiments to characterize the fluid. The approach developed in this study uses a cubic equation of state to solve for vapor/liquid/liquid equilibrium (VLLE), where asphaltene is the denser liquid phase. Precipitation from the liquid mixture occurs as its solubility is reduced either by changes in pressure (natural depletion), or composition (i.e. mixing resulting from gas injection). The dynamic relationship between phase composition, pressure, and porosity/permeability is modeled with a finite differences reservoir simulator and solved using an implicit-pressure, explicit-saturations and explicit-compositions (IMPESC) direct sequential method. The robustness of this model is validated by the ability to reproduce experimental asphaltene precipitation data while predicting the expected phase behavior envelope and response to key thermodynamic variables (i.e. type of components and composition, pressure and, temperature). The three-phase VLLE flash provides superior thermodynamic predictions compared to existing commercial techniques. Computer performance analysis showed that the model has a comparable cost to existing asphaltene precipitation models, taking only 1.1 more time to calculate but requiring fewer tunable parameters. The VLLE flash was in average 4.47 times slower compared to a conventional two-phase vapor/liquid flash. This model has the speed of a flash calculation while maintaining thermodynamic consistency, enabling efficient optimization of reservoir development strategies to mitigate the detrimental effects of asphaltene precipitation on productivity.
192

Stereoscopic head-tracked displays : analysis and development of display algorithms

Wartell, Zachary Justin 08 1900 (has links)
No description available.
193

Community development in Rainy River First Nations: a study of self-sufficiency and land-culture

Blackburde, Gordon Lyle 20 August 2013 (has links)
Due to government intervention the inhabitants of Rainy River First Nations were deprived of the material resources available to many Canadians. In 1914, the federal government established a community reserve that consisted of peoples from eight separate and distinct communities, which directly contravened Treaty Three. The paper (through interviews, observation and textual analysis) provides a critical overview of the community's land claims settlement and reclamation process, and struggle for sustainability in the twenty-first century. In addition, it examines the manner that land-culture, human resources and capital resources may be applied to revitalize the community through community development and economic strategies.
194

Comparison of septal defects in 2-D and 3-D echocardiography using active contour models

Lassige, Timothy A. 05 1900 (has links)
No description available.
195

Motion artifact detection in transthoracic 3-D echocardiography

Rhodes, Caroline Lee 05 1900 (has links)
No description available.
196

New generation three-phase rectifier

Phipps, William January 2009 (has links)
This thesis describes the development of a new generation of three-phase rectifier, used to power telecommunications equipment. The traditional topology for such power converters is a single-phase two-stage design, with a boost converter providing power factor correction at the input to the first stage and an isolated dc-dc converter making up the second stage. A two-stage design results in the output power being processed twice and this cascade effect results in an overall reduction in efficiency. A rectifier solution is sought that meets with all the requirements of the telecommunications industry, while not displaying the inherent weaknesses associated with a boost-derived topology, and which can be realised in a single-stage design. A number of common three-phase topologies exist that could be realised as telecommunication power supplies, however, they do not completely satisfy all the industry requirements. A new three-phase rectifier, which is a single-stage buck-derived topology, is proposed. As a consequence of incorporating a buck-derived topology, the three-phase rectifier does not exhibit any issues resulting from startup inrush currents, or high currents due to an output short circuit condition, as would result in a boost-derived topology. The new proposed rectifier is modular in nature, which has the added benefit of redundancy. As a result of the new three-phase rectifier having a single-stage topology, it is expected that the overall efficiency would able to reach close to 95%. This is due to the traditional two-stage designs having efficiencies around the 90% mark, and therefore by removing a stage, out of the power conversion process the overall losses would also be halved, resulting in the 5% gain in efficiency. The rectifier system requires only one controller as a result of being a single-stage design, thus also reducing the overall system cost. Simulations show that if this topology is combined with a three-phase phase-locked loop controller it can meet the industry compliance standards. The thesis follows the development of the three-phase power converter from the simulation stage to the realisation of the control hardware and stability modelling. It also provides a detailed report of an investigation into the power converter system’s performance. The thesis concludes with discussions concerning the viability of the new topology as a commercial product and indicates areas of possible future research and development.
197

THREE-DIMENSIONAL QUANTITATIVE ANALYSIS OF THE TRAJECTORY OF THE FOOT WHILE RUNNING

Cunningham, Thomas J. 01 January 2007 (has links)
Exercising the leg in a manner similar to running is theorized to have the potential effect of increasing performance and reducing occurrence of injuries in running athletes. Development of an exercise device that can help facilitate this method of specificity training could be beneficial to the sports community and should be investigated. Understanding the trajectory of the foot during the running gait is primary to further pursue this concept. 26 running athletes of varying characteristics participated in this study. Each subjects sex, age, weight, height, leg length, activity level and participation amount in their respective sport was recorded. Retro-reflective cameras captured the three-dimensional trajectory of each subjects right leg while running at speeds of 2, 3.8, 4.52 and 5.36 m/s for 10-15 seconds on a treadmill, respectively. The range of foot movement in each cardinal plane was determined for each speed. An ANCOVA revealed that leg length was the most determinate factor in trajectory range differences among subjects. Subjects were subsequently divided into quartiles based on leg length where further analysis revealed that foot displacement increased vertically and horizontally in the sagittal plane with increases in speed while trajectory in the third plane remained constant and substantially less in magnitude.
198

Versus Associations : The familiarity between different influences. Patched together.

Ida, Pettersson January 2014 (has links)
In this text I am investigating the relationship between craft, fine art and kitsch/popular culture through the making of a three-dimensional pattern in patchwork technique. I apply the investigation to my working technique by comparing certain examples of fine art pieces with kitsch items. A method that during the process was named Versus Associations. I have connected the art pieces and kitsch items through this method of associations based on their similarities in colors and composition. The aim of the pattern is to mediate color interactions that make up a visual illusion. I want to make the beholders curious of what is happening in the pattern and show that it can affect them physically. / <p>Due to copyright some pictures has been removed. Numbers, representing these pictures, with attached web links can be found in references.</p>
199

Community development in Rainy River First Nations: a study of self-sufficiency and land-culture

Blackburde, Gordon Lyle 20 August 2013 (has links)
Due to government intervention the inhabitants of Rainy River First Nations were deprived of the material resources available to many Canadians. In 1914, the federal government established a community reserve that consisted of peoples from eight separate and distinct communities, which directly contravened Treaty Three. The paper (through interviews, observation and textual analysis) provides a critical overview of the community's land claims settlement and reclamation process, and struggle for sustainability in the twenty-first century. In addition, it examines the manner that land-culture, human resources and capital resources may be applied to revitalize the community through community development and economic strategies.
200

Rådgivningsstöd, kunskapsstöd eller avlastningsstöd? : En studie om avdelningschefers behov av HR-stöd

Williamsson, Andreas, Sandin, Bastian January 2014 (has links)
Studien är skriven på uppdrag av den studerade organisationen och är en del i det förbättringsarbete som organisationens HR-funktion genomför. Uppdraget har syftat till att undersöka avdelningschefers uppfattning gällande behovet av HR-stöd i deras arbete. Syftet specificeras utifrån studiens tre forskningsfrågor; (1) Vilka HR-uppgifter ansvarar avdelningscheferna över i deras arbete? (2) Inom vilka HR-uppgifter anser sig avdelningscheferna ha behov av stöd? (3) Hur kan behovet av stöd bemötas enligt avdelningscheferna? Vi har genomfört 10 semistrukturerade intervjuer med organisationens avdelningschefer. Resultatet av vår studie har visat att av de sex HR-uppgifter som avdelningschefer utför önskas stöd i fyra av dessa. Behovet av stöd varierar mellan och inom specifik HR-uppgift och bemötandet av detta behov önskas enligt avdelningscheferna ske via tydliggörande av rollerna och utifrån tre former av stöd; rådgivnings-, kunskaps- och avlastningsstöd. En organisering av HR bör därför bottna i vilket behov linjecheferna har utifrån vardera stödform och hur dessa kan variera. En förutsättning för detta är att  goda relationer skapas så att HR upplevs som tillgängliga där rollerna och förväntningarna är uttalade.

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