Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 85 for “"Loss Mechanisms"”.
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Turbine tip clearance loss mechanisms
… actual turbine environment, on turbine blade tip loss. The calculations were carried out for a subsonic high pressure turbine stage. The loss mechanism examined is that due to tip clearance vortex mixing. The effects examined were three-dimensional blade stacking, downstream transition duct …
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Loss mechanisms in turbine tip clearance flows
… clearance ow have been carried out to dene the loss generation mechanisms associated with tip leakage in unshrouded axial turbines. Mix- ing loss between the leakage, which takes the form of a strong embedded streamwise vortex (u=ux 1 in the vortex core), and the mainstream ow is found to be the …
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High Fidelity Simulation of Loss Mechanisms in Compressors
… efficiencies require better understanding of loss mechanisms. The rise of high performance computing is unlocking the potential of scale-resolving simulations for industrially relevant cases thus allowing new levels of simulation fidelity. As a result, previously unexplored effects of …
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Extraction of turbomachinery loss mechanisms from high-fidelity simulations
… identification of several turbulence producing mechanisms. For the axial test case, turbulent transition was driven by separation bubbles on both pressure and suction surfaces and structures associated with the separation bubbles were identified to contribute to raising the entropy of the flow …
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Loss mechanisms in a highly loaded transonic axial turbine stage
… turbine technology is assessed for its role in loss generation. Steady and unsteady two-dimensional and three-dimensional flow computations, complemented by simplistic control volume analyses as well as test data, provided results for establishing the quantitative level of loss from various …
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Efficiency loss mechanisms in colloidal quantum-dot light-emitting diodes
… (EQE). In this thesis, we study the efficiency loss mechanisms present in the latest generation of QD-LEDs. We start with understanding the origin of reduced efficiencies at high current density operation, known as the efficiency roll-off. Through simultaneous measurement of quantum dot (QD) …
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A Data-Centric Approach to Loss Mechanisms for Compressor Preliminary Design
… It is shown using 2D data that a new profile loss model can be developed which halves the error in preliminary design correlations and generalises well to turbines as well as compressors. The reason for these improvements is shown to be the result of a more physically accurate decomposition …
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Analysis of loss mechanisms in superconducting windings for rotating electric generators
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981.
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Numerical Study of Energy Loss Mechanisms in Oscillating Underwater Explosion (UNDEX) Bubbles
… is known to be due to neglected secondary energy-loss mechanisms is evaluated. A single secondary energy-loss mechanism is established as the most significant loss mechanism that is being disregarded in current hydrocodes. The leading secondary energy-loss mechanism is formulated into a …
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The Impact of Combustor Turbulence on Loss Mechanisms in the High Pressure Turbine
… the effect of combustor turbulence on the loss mechanisms which occur in a turbine blade row. The thesis has a number of important findings. The combustor turbulence is characterised and is shown to be isotropic in nature. It shows that, when no pressure gradient is present, combustor …
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High Yield Fabrication of Monolayer WSe₂ Mechanical Resonators and a Study of Their Loss Mechanisms
… road is understanding the dominant mechanical loss mechanisms in monolayer WSe<sub>2</sub> mechanical resonators. In this thesis, I describe the method I have developed to fabricate fully suspended monolayer WSe<sub>2</sub> mechanical resonators using a high yield fabrication method based on …
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An experimental study on the effects of blade row interactions on aerodynamic loss mechanisms in a multistage compressor
… interactions on embedded stator total pressure loss and boundary layer transition in the Purdue 3-stage axial compressor. The inlet guide vane, Stator 1, and Stator 2 all have 44 vanes which enable vane clocking of the embedded stage, while the rotors have different blade counts producing …
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Characterization of industrially processed chalcopyrite solar cells with varied absorber composition
In the present thesis by publication loss mechanisms in industrially processed chalcopyrite thin film solar cells of the conventional ZnO:Al/i-ZnO/CdS/Cu(In,Ga)(Se,S)2/Mo layer structure investigated. The results of this thesis were obtained within two independent projects with different industry …
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An analysis of energy balance in a helicon plasma source for space propulsion
… source as it relates to the analysis of power losses. A helicon plasma is a rather complex system with many potential loss mechanisms. Among the most dominant are optical radiation emission, wall losses due to poor magnetic confinement, and poor antenna-plasma coupling. This work sought to …
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Automated infrared fiber optic characterizer
Recent progress in reducing the extrinsic losses of fluorozirconate optical fibers has increased the material research efforts for these new waveguides. Fluorozirconate fibers, which are inherently more transparent than silica fibers, are predicted to have intrinsic losses as low as 0.001 dB/km at …
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Core loss characterization and design optimization of high-frequency power ferrite devices in power electronics applications
An impedance-based core loss measurement technique for power ferrites, the modeling and analysis of mechanisms of high-frequency losses, and design methodology for optimization for high-frequency magnetics are presented. The high-frequency losses of ferrite materials are characterized employing a …
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Longitudinal misalignment based strain sensor
… a segment of hollow core fiber. Related splice loss mechanisms are investigated for their effect on resolution. The effect of gauge length and launch conditions are also investigated.
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Sparking an increase in volumetric and specific density for power converters with avant-garde thermal management strategies, topologies, and packaging schemes
… requires a thorough understanding of the loss mechanisms for each component and non-traditional thermal management strategies with high heat flux potential. After summarizing the current achievements for both power component loss characterization and the direct cooling of electronics with …
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Characterisation of mechanical loss in fused silica ribbons for use in gravitational wave detector suspensions
… involves characterisation of the mechanical losses in fused silica ribbon fibres to determine their potential for use in suspending the 40kg test masses for Advanced LIGO. The design of fibres is discussed here, demonstrating the advantages of rectangular cross sections over the circular …
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Aerodynamics of Low Pressure Steam Turbine Exhaust Systems
… still lack understanding of the flow physics and loss mechanisms in the exhaust system, especially at part-load conditions. It is also unclear how the exhaust system should be designed when its required operating range widens. This thesis provides solutions to these aerodynamic issues through …
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