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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.
31

Relations all the way down? Exploring the relata of Ontic Structural Realism

Taylor, Jason D. Unknown Date
No description available.
32

Transformation of Muscle Architecture at the Fiber Bundle Level to Fit Parametric B-spline Volumes: Extensor carpi radialis brevis and longus

Ravichandiran, Mayoorendra 27 July 2010 (has links)
Most models of the musculoskeletal system incorporate individual or groups of muscles as a series of line segments, assuming all fiber bundles within a muscle have the same length and moment arm, and do not account for architectural differences throughout the muscle volume. The purpose was to develop an algorithm to fit digitized fiber bundle data from one specimen into muscle volume and intramuscular nerve distribution data from seven other specimens of extensor carpi radialis longus (ECRL) and brevis (ECRB). Coherent Point Drift (CPD) algorithm was successfully adapted for this purpose. The intramuscular nerve distribution and fiber bundle architecture was modeled in all the muscle volumes. ECRL was found to have two neuromuscular compartments, superficial and deep, while ECRB was found to have two, three or four, in a proximal to distal direction depending on the number of primary nerve branches.
33

Transformation of Muscle Architecture at the Fiber Bundle Level to Fit Parametric B-spline Volumes: Extensor carpi radialis brevis and longus

Ravichandiran, Mayoorendra 27 July 2010 (has links)
Most models of the musculoskeletal system incorporate individual or groups of muscles as a series of line segments, assuming all fiber bundles within a muscle have the same length and moment arm, and do not account for architectural differences throughout the muscle volume. The purpose was to develop an algorithm to fit digitized fiber bundle data from one specimen into muscle volume and intramuscular nerve distribution data from seven other specimens of extensor carpi radialis longus (ECRL) and brevis (ECRB). Coherent Point Drift (CPD) algorithm was successfully adapted for this purpose. The intramuscular nerve distribution and fiber bundle architecture was modeled in all the muscle volumes. ECRL was found to have two neuromuscular compartments, superficial and deep, while ECRB was found to have two, three or four, in a proximal to distal direction depending on the number of primary nerve branches.
34

Heat Transfer in a High-pressure Gas-solid Fluidized Bed with Horizontal Tube Bundle and Continuous Addition of Fines

Li, Fang 17 August 2018 (has links)
Climate change is becoming more severe than ever in human history and the emission of green house gas urgently needs to be reduced while global energy consumption remains booming. Large-scale application of clean fossil fuel combustion shall be considered as a priority for its economical advantages as well as reliability in meeting global energy needs. Oxygen-fired pressurized fluidized bed combustor technology with downstream carbon capture and sequestration is considered a key approach to clean coal combustion. In such technology, the fluidized bed combustor operates at elevated pressures and houses an in-bed heat exchanger tube bundle. It is essential to understand the rate of heat transfer between the immersed heat exchange surface and the fluidized bed as it is a key parameter in heat exchanger design. The goal of this work was to investigate the impact of pressure and presence of fine particles (i.e., surrogate for pulverized fuel) on the overall tube-to-bed heat transfer coefficient. Experiments were conducted in a pilot-scale fluidized bed with an inner diameter of 0.15 m under cold flow conditions. A tube bundle consisting of five horizontal staggered rows was completely submerged in the bed. One of the tubes was replaced by a heating cartridge housed in a hollowed copper rod. Five thermocouples distributed at 45º intervals along the copper rod circumference measured the surface temperature and ensured that local effects were included. The bed material was large glass beads of 1.0 mm in diameter while the fines were glass beads of 60 µm in diameter and thus susceptible to entrainment. The fine particles were continuously fed to the fluidized bed and then captured downstream by a filter system. Fluidization was conducted at 101, 600 and 1200 kPa with excess gas velocities (Ug - Umf) of 0.21, 0.29 and 0.51 m/s. Fine particle feed rates were 0, 9.5 and 14.4 kg/h. Two heating rod positions (2nd row and 4th row) were studies. Overall, the heat transfer coefficient approximately doubled when pressure was increased from 101 to 1200 kPa. At atmospheric conditions, where the slug flow regime occurred, the maximum heat transfer coefficient was at the bottom of the rod, while it moved to the side of the rod at high pressures where the bubbling regime occurred. As the heating rod moving from 2nd row to the 4th row, the averaged heat transfer coefficient increased by respectively 18%, 9% and 6% at 101, 600 and 1200 kPa. The addition of fine particles decreased the average heat transfer coefficient by 10 to 20 W/m2 K where the time – averaged heat transfer coefficient was approximately 220 and 450 W/m2K at 101 kPa and 1200 kPa respectively. There was no effect on the angular profile across the tube surface. The results showed that average heat transfer coefficients matched the correlation developed by Molerus et al. (1995) within a 5% difference across all conditions when fines were not present.
35

Structure of Turbulent Flow in a Rod Bundle

Don, Armel January 2016 (has links)
The structure of turbulence in the subchannels of a large-scale 60 degree section of a CANDU 37-rod bundle was studied at Reynolds numbers equal to 50,000, 100,000 and 130,000. Measurements were conducted at roughly 33.81 rod diameters from the inlet of the rod bundle using single-point, two-component hot-wire anemometry. Analysis of the axial velocity signal indicated a weak effect of Reynolds number on the axial velocity distribution and a bulging of axial velocity contours toward the narrow gaps. The normalised normal Reynolds stresses and the normalised turbulent kinetic energy were found to decrease as the Reynolds number increased. The radial Reynolds shear stress varied linearly with radial distance from the rod, crossing zero at the location of local maximum of the axial velocity. This stress was symmetric about the central rod whereas the azimuthal Reynolds shear stress was anti-symmetric. The Reynolds number effect was weak but measurable on the integral length scales of the axial and radial velocity fluctuations but negligible on the integral length scale of the azimuthal velocity fluctuations, especially in the gap regions. The Taylor and Kolmogorov microscales increased from the wall toward the centre of the subchannel and decreased as the Reynolds number increased. The wall shear stress stress distribution around the central rod indicated no effect of Reynolds number, when normalized by the corresponding average. The wall shear stress reached local minima at rod-wall and rod-rod gaps and local maxima in the open flow regions. Vortex streets were generated within the subchannels very close to the inlet of the rod bundle. The convection speed and frequency of the vortex street were found to increase proportionately to Reynolds number, whereas the vortex spacing was not affected by the Reynolds number.
36

LES and Hybrid RANS/LES turbulence modelling in unstructured finite volume code and applications to nuclear reactor fuel bundle

Rolfo, Stefano January 2010 (has links)
Rod bundle is a typical constitutive element of a very wide range of nuclear reactor designs. This thesis describes the investigation of such geometry with wall-resolved Large Eddy Simulation (LES). In order to alleviate the mesh constraint, imposed by the near wall resolution, the usage of embedded refinements and polyhedral meshes is analysed firstly with a inviscid laminar case (Taylor Green vortices) and secondly with a fully turbulent case (channel flow only with embedded refinement). The inviscid test case shows that the addition of embedded refinements decreases the conservation properties of the code. Indeed the accuracy decreases from second order in a structured conformal mesh, to something in between first and second order depending on the quality of the unstructured mesh. Better results are obtained when the interface between refined and coarse areas presents a more regular and structured pattern, reducing the generation of skewed and stretched cells. The channel flow simulation shows that the Reynolds stresses, of some embedded refined meshes, are affected by spurious oscillations. Surprisingly this effect is present in the unstructured meshes with the best orthogonal properties. Indeed analysis of Reynolds stress budgets shows that terms, where the gradient in the wall normal direction is dominant, have a largely oscillatory behaviour. The cause of the problem is attributed to the convective term and in particular in the method used for the gradient reconstruction. As a consequence of these contradictory signs between the inviscid and the fully turbulent cases, the rod bundle test case is analysed using a conventional body fitted multiblock mesh. Two different Reynolds numbers are investigated reporting Reynolds stresses and budgets. The flow is characterised by an energetic and almost periodic azimuthal flow pulsation in the gap region between adjacent sub-channels, which makes turbulent quantities largely different from those in plane channel and pipes and enhances mixing. Experiments found that a constant Strouhal number, with the variation of the Reynolds number, characterises the phenomenon. The frequency analysis finds that present simulations are distinguished by three dominant frequencies, the first in agreement with the experimental value and two higher ones, which might be due to the correlation of the azimuthal velocity in the streamwise direction. Several passive temperature fields are added at the simulations in order to study the effects of the variation of the Prandtl number and the change in boundary conditions (Neumann and Dirichlet). A simplified case where an imbalance of the scalar between adjacent sub-channels is also investigated in order to evaluate the variation of the heat fluxes with respect to the homogeneous case. An alternative solution, to reduce the mesh constraint imposed by the wall, is to hybridize LES with RANS. The main achievement of this work is to integrate the heat transfer modelling to the already existing model for the dynamic part. Further investigations of the blending function, used to merge the two velocity fields, are carried out in conjunction with a study of the model dependency on the mesh resolution. The validation is performed on a fully developed channel flow at different Reynolds numbers and with constant wall heat flux. On coarse meshes the model shows an improvement of the results for both thermal and hydraulic parts with respect to a standard LES. On refined meshes, suitable for wall-resolved LES, the model suffers from a problem of double counting of modelled Reynolds stresses and heat fluxes because the RANS contribution does not naturally disappear as the mesh resolution increases.
37

Bundle Burials at Ajvide/Jakobs : A taphonomic interpretation

Pettersson Svärd, Johanna January 2021 (has links)
The burial type referred to as bundle burials was a rare occurrence during the Neolithic era and little research has been done on the topic. Three graves from the Ajvide/Jakobs site at Eksta parish, Gotland have been identified as this specific type of burial. There are several potential explanations to why this type of burial would potentially occasionally be implemented or why the excavated remains would be found in this types of positions. The purpose of this thesis is to present and search for different explanations to this phenomenon. Furthermore, the main purpose of the study is to explore how taphonomic research can potentially deepen our knowledge regarding rituals and practices of the past, particularly within the field of mortuary archaeology. / Paketgravar under den neolitiska perioden är en ovanlig förekomst och lite forskning har gjorts om ämnet. Totalt tre paketgravar har identifierats vid Ajvide /Jakobs, Eksta socken på Gotland. Det finns många möjliga förklaringar till varför denna typ av begravning potentiellt skulle kunna praktiserats eller varför benelementen skulle kunna påträffats i dessa typer av positioner. Syftet med denna uppsats är att presentera och undersöka olika möjliga förklaringar till detta ovanliga gravskick. Vidare är syftet med studien även att utforska hur tafonomisk forskning potentiellt kan fördjupa vår kunskap om ritualer från det förflutna, framförallt inom gravarkeologi.
38

Modulární jádro pro informační systém / Modular core for information system

Ruml, Martin January 2010 (has links)
This thesis deals with frameworks for modular information systems. The experimental implementation module for dynamic loading of others running modules is realized in thesis on the basis of research. In first chapters there are the description of solved problems of modular systems and the description of used programming language Java. Other chapter describes the specifications for modular system OSHi. Other chapter describes framework Esclipse RCP. Eclipse RCP is used for the formation of graphics of riched aplication. The experimental module is creative at the end of the thesis. The program uses Eclipse RCP for grant of GUI for control of loading of modules.
39

Topology and Stability of Core and Loop Variants of a Four-Helix Bundle Protein

Wolf, Erin Michelle January 2021 (has links)
No description available.
40

Code Sepsis: The Time to Act is Now

Bradshaw, William 21 March 2022 (has links)
No description available.

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